TRANSMISSION ELEMENT FOR A POWER TRANSMISSION SYSTEM

Technical field

The present invention relates to the field of power transmission systems and in particular to a transmission element for an power transmission system, to a power transmission system, to a method to operate a power transmission system and to an automotive vehicle (e.g. motor vehicles, watercrafts etc.) comprising a power transmission system

Technical background

Known automotive vehicles, such as trucks, cars, motorbikes or the like, use power transmission systems (e.g. gearboxes) in order to provide a range of speed and torque outputs, which are necessary during the movement of the vehicle.

The power transmission system adapts the output of the engine of the vehicle, typically an internal combustion engine, to the drive wheels. For example, automotive engines may operate at a relatively high rotational speed, which is inappropriate for starting, stopping, and slower travel of the vehicle. The power transmission system thus may reduce higher engine speed to the slower wheel speed, increasing torque in the process. Further, if higher travel speeds (or wheel speeds) are desired, a power transmission system may be designed to increase rotational speed of the engine.

Furthermore, the engine provides its highest torque and power outputs unevenly across the rev range resulting in a torque band and a power band. Often the greatest torque is required when the vehicle is moving from rest or traveling slowly, while maximum power is needed at high speeds. Therefore, a power transmission system is required that transforms the engine’s output so that it can supply high torque at low speeds, but also operate at high speeds with the motor still operating within its limits.

However, those known systems cannot continuously transfer power during the automated gear shifting. Further, during gear shifting, these known systems suffer from energy loss due to friction between clutch disks or the like, such as in CVTs and DSGs.

Transmission elements such as gear wheels or dog clutches (or engagement components) are well known and used in gearboxes for example of automobiles as well as of motor boats. During gear changing the gears are constantly rotating such that high wear and tear forces act on the gearbox components while shifting from one gear to another, i.e. when a dog clutch locks different gears to the rotating shafts. Such forces are commonly limited by using synchronizing mechanism that match the speed of the gear to that of the shaft.

Therefore, a short pause is often required, for example between changing from forward to reverse gear of a motorboat. During this pause, i.e. the neutral stage, the power source is disengaged from the transmission. Thus, the speed of the engine more closely matches the speed of the new gear and torque spikes are reduced when the engine is re-engaged to the transmission.

Further, to allow a quicker and smoother shifting, elastic elements are arranged within power transmission systems especially gearboxes to absorb the impact on the components during shifting processes. This can reduce unwanted noises and provide the user with a higher quality shifting feel, as well as increasing the lifetime of the transmission.

Thus, it is the object of the present invention to provide a transmission element for a power transmission system, particularly for automotive vehicles, that at least partly overcomes the aforementioned drawbacks. In particular, the power transmission system allows for a smooth gear change, for continuously transferring power when shifting gear ratios and for reduced power losses due to friction.

Prior transmission systems using divided gear wheels are known from US 1162305 A, WO 2008/062192 and DE 219963 A. US 1162305 A relates to a divided gear wheel with one elastic element. It’s known that without a synchronizing engagement mechanism. This means, that, when there is an absence of clutch disks, the difference in rotation between the two parts that are going to be engaged, have to be significant small (< 20 RPM) otherwise the dog clutch and the assign gear will refuse to engage or the tooth will failure, because the divided gear wheel has one spring. That’s for handling the load and so the elastic constant should be great. (Can’t be small that a smooth engagement requires, because exist danger of plastic deformation).

In WO 2008/062192 A1 inner/outer part of divided gear wheel connected with resilient means adapted in series to overhaul torque peaks upon engagement or elastic constant as dumpling elements.

It’s a passive method to overhaul the torque peaks upon engagement, with “large engagement windows provide greater opportunities to fully engage gear wheel” and when dog clutch teeth engage with inner part of divided gear wheel the occurring torque peak have a loud grinding sound or can damage the divided gear wheel or dog clutch , that’s why adopt resilient elements.

If dog clutch and inner part of divided gear wheel had a tooth engagement, the tooth of engagement component would refuse to engage or could have a tooth failure. When resilient means adopted in series arrangement the applied total load is the same for each one of the resilient elements and as far all elastic elements have a limit to extend, pressed or torsioned the difference in elastic constant of each one of elastic element is restricted from the max aloud deformation of elastic elements. In DE 219963 A is disclosed concentric wheels and not divided gear wheel.

The softer element is used to handle the occurring load and the stiffer to handle the torque peaks.

It’s a manner to overhaul torque shocks.

A transmission element of a power transmission system according to the present invention comprises at least one first part and at least one second part which is rotatable relative to the at least one first part about a common axis by a limited degree. Further, the transmission element comprises at least one first elastically deformable element (first elastic element). The elastic element is arranged between the at least one first part and the at least one second part in at least one compartment formed by the at least one first part and the at least one second part, wherein the elastic element biases the at least one first part and the at least one second part rotationally away from each other in opposite directions. The transmission element further comprises at least one second elastically deformable element (second elastic element) arranged within the at least one compartment between the at least one first part and the at least one second part, wherein the at least one second elastic element is arranged parallel to the at least one first elastic element, and in that the elastic elements comprise different suspension rates and/or different lengths.

The elastic elements are positioned in a parallel configuration (with the presented exemplary elastic element configurations being the one elastic element within the other, the one elastic element on top of the other, the one elastic element next to the other, with the presented exemplary configurations considered being parallel configurations) in relation to each other and that the at least one first elastic element is longer in relation to the at least one second elastic element and as a result, the at least one second elastic element deforms after a certain deformation of the at least one first elastic element.

Summary of the invention

The present invention provides a solution according to the subject matter of the independent claims. In particular, the objects are at least partly achieved by a transmission element for a power transmission system, wherein the transmission element comprises an inner part, being engageable with a shaft and an outer part, comprising teeth for torque transmission with another gear wheel. The inner part and the outer part have a common rotational axis. Further, the inner part is at least partially arranged within the outer part and the inner part is coupled to the outer part by means of at least one set of two elastic elements, so that the inner part is arranged angularly deflectable with respect to the outer part around the common rotational axis. The inner and the outer part are adapted to rotate with the same angular speed if the elastic elements are fully loaded.

The transmission element may be a divided gear wheel or a selector, e.g. a dog clutch type selector (or an engagement component).

The inner part can transfer force and/or torque to the outer part via the elastic element(s). If the inner part is angularly deflected with respect to the outer part the corresponding elastic element is compressed or decompressed, depending on the direction of deflection and the arrangement of the elastic element. Further, inner part can be coupled to the outer part by means of multiple elastic elements. Due to this compression/decompression of the elastic elements, forces and/or torque can be transferred from the inner part to the outer and vice versa.

When the transmission element is a divided gear wheel, the inner part is engageable with a shaft, such as an input shaft or an output shaft, with the help of engagement component, with the engagement component being a transmission element as well.

The engagement component is torque proof connected with the shaft, but axially moveable to the shaft.

Accordingly, rotational forces can be transferred from the inner part of the divided gear wheel to the shaft and vice versa. The outer part of the divided gear wheel, forms the actual gear portion and comprises teeth. Accordingly, the outer part may comprise any type of gearing, such as a spur gear, a helical gear, a screw gear, a bevel gear, a spiral beveled gear, hypoid gear, a crown gear, a worm gear, or the like.

As the inner part is deflectable with respect to the outer part and is coupled to the outer part by means of at least one set of two elastic elements, differences in angular velocity during a gear ratio changing action can be compensated and power losses can be reduced. This is, as during the gear ratio changing action the elastic element is loaded, due to a difference in angular velocity between the inner part of the divided gear and an engagement component (in case the divided gear is a free gear) or due to a difference in angular velocity between the outer part and the inner part (in case the divided gear is a fixed gear). The loaded elastic element thus can store power and return the stored power to the system that otherwise would lead to losses (loses in discs clutch connecting the engine with gearbox).

The elastic element can be a spring element, such as a torque spring or a spiral spring, or any other elastic element, such as a rubber element. Further, different types of elastic elements can be combined in a divided gear wheel in order to achieve a desired spring characteristic.

The at least two elastic elements may be a spring elements and may be received within a spring compartment, formed by the inner part and the outer part. In particular, the spring compartment can be a closed compartment. Alternatively, the spring compartment may be an open compartment that allows heat exchange and a facilitated maintenance of the springs.

The divided gear wheel may further comprise at least one set of two elastic elements or even more sets of two elastic elements, wherein the elastic elements may be arranged evenly distributed in a circumferential direction. By providing several elastic elements, the spring characteristics can be adjusted more easily. Further, it is possible to combine spring and damping elements. The maximum deflection angle of the inner part is inter alia dependent on the number of elastic elements used. If only one set of two elastic element is provided, the maximum deflection angle may be well above 180°, e.g. in a range of 200° to 240°. In case of multiple elastic elements that are arranged evenly distributed in a circumferential direction, the maximum deflection angle, and thus the available engagement time, is reduced.

Particularly, a first spring element may be partially arranged within a second spring element and may protrude out of the second spring element on a front face, wherein a spring rate of the first spring element may be lower than a spring rate of the second spring element. Since the first elastic element protrudes out of the second elastic element it is obvious that the first elastic element is longer in relation to the second elastic element.

For example, a set of two spring elements can be incorporated in a divided gear wheel. The set of spring elements will comprise one spring element having a bigger diameter concentrically placed to a spring element having a smaller diameter. Further, because these spring elements have different spring rates, the“softer” spring element will begin to deform initially upon deflection of the inner or outer part and subsequently the “stiffer” spring element will be deformed, with this feature being a consequence of the difference in lengths of the elastic elements in relation to each other and the designs layout. Thus, a step-wise spring characteristic can be achieved, resulting in smooth gear ratio changing actions. Further, with providing a “softer” spring element, the engagement between the inner part and the respective shaft is facilitated. Particularly, the engagement between the engagement means of the inner part and a respective engagement component is facilitated, as the force that is required to move the engagement component axially into engagement (e.g. by a sequential shift actuator as will be described in greater detail below) can be reduced.

Further, the inner part may comprise engagement means that are adapted to engage with an engagement component of a power transmission system, wherein upon engagement, the inner part is torque proof engaged with a shaft. The engagement means can be provided on an inner circumferential surface of the inner part, facing an assigned shaft. Further, engagement means can be provided on a front face of the inner part of the divided gear wheel. The engagement means can comprise teeth, grooves and/or recesses.

The objects are further at least partly achieved by a power transmission system, e.g. for an automotive vehicle, that comprises an input shaft, supporting input gear wheels and an output shaft, supporting output gear wheels. Each input gear wheel assigned to the input shaft engages with a corresponding output gear wheel assigned to the output shaft, thereby defining a gear ratio. At least one of the gear wheels assigned to the output shaft and/or at least one of the gear wheels assigned to the input shaft of a gear ratio is a divided gear wheel as described above. The power transmission system further comprises at least one engagement component that is assigned to the input shaft or the output shaft and to at least a divided gear wheel. The engagement component is arranged axially movable along the assigned shaft to change a gear ratio, wherein the engagement component is adapted to engage with the inner part of the divided gear wheel, thereby torque proof fixing the inner part with the assigned shaft.

A gear ratio is formed by two gear wheels, wherein a first gear wheel is a fixed gear wheel, i.e. permanently engaged with a shaft, and a second gear wheel is a free gear wheel, i.e. adapted to be temporarily engaged with a shaft. Either of the first or second gear wheels can be assigned to the input or the output shaft.

Further, at least one of the first and second gear wheels is a divided gear wheel as described above. As the inner part of the divided gear wheel is deflectable with respect to the outer part of the divided gear wheel and as the inner part is coupled to the outer part by means of at least one set of two elastic elements, differences in angular velocity during a gear ratio changing action can be compensated and power losses from clutch disc connecting engine with gearbox can be reduced.

The input shaft may be powered by an engine and the output shaft may be adapted to power the wheels of an automotive vehicle. By engaging the engagement component with an assigned divided gear wheel, the inner part of the divided gear wheel is torque proof fixed to the assigned shaft. By this engagement of the engagement component with the divided gear wheel power transfer can be achieved.

Accordingly, by engaging different divided gear wheels different gear ratios can be chosen.

The engagement component can be assigned to a single divided gear wheel or to multiple divided gear wheels.

During the gear ratio changing action two divided gear wheels are engaged with the engagement component. After the completion of engagement only one divided gear wheel is engaged with the engagement component as will be explained in greater detail further on.

The engagement component may be arranged concentrically to the assigned shaft and the axial movement of the engagement component along the assigned shaft may be guided by straight or helical means, so that the engagement component is rotated relative to the assigned shaft upon axial movement.

In an initial state, the power transmission system may operate with a first gear ratio. Accordingly, power is transferred from the input shaft to the output shaft by means of a first pair of gear wheels that define the first gear ratio. A second gear ratio may be defined by a second pair of gear wheels.

To change the gear ratio, form the first to the second gear ratio, the free gear wheel of the first pair of gear wheels must be disengaged and the free gear wheel of the second pair of gear wheels must be engaged with the respective shaft. The engagement is achieved by means of an engagement component that is assigned to the free gear wheel of the second pair of gear wheels.

In the initial state, the engagement component rotates with an angular velocity that is different from the angular velocity of the free divided gear wheel of the second pair of gear wheels. By guiding the engagement component along the assigned shaft by helical means, so that the engagement component is rotated relative to the assigned shaft upon axial movement, the engagement component can be rotationally accelerated (or decelerated) in order to at least partially synchronize with the angular velocity of the free gear wheel of the second pair of gear wheels.

Thus, upon engagement, the engagement component rotates with an angular velocity similar to that of the free gear wheel of the second pair of gear wheels. Remaining differences can be compensated by the elastic element. Thus, power can be transferred permanently during the gear ratio changing action.

The helical means may be integrally formed with the assigned shaft. In particular, the helical means can comprise at least one helical groove or at least one helical protrusion that is adapted to guide the engagement component helically, i.e. in a combined axial and rotational movement. An integrally formed helical means allows for a facilitated assembly of the power transmission system. Further, the helical means can be provided in form of a separate part that is torque proof engaged with the assigned shaft. Thus, the dimensions of the actual shaft can be reduced, and notch tension can be avoided. The helical means may comprise a helix angle a, that follows the equation

or

wherein Dw defines a difference in angular velocity at the beginning of a gear ratio changing action between the assigned shaft and a gear wheel to be engaged, wherein Ua is a desired velocity of the axial movement, and wherein R is the effective radius of the helical means. U _v is the vertical velocity of the engagement component.

By choosing the helical angle a and the desired velocity of the axial movement Ua according to the above equation the absolute values of the angular velocities of the engagement component and the respective divided gear wheel that is going to be engaged, are substantially equal upon engagement and as a result smooth engagement can be achieved. In particular, a difference in angular velocity Dw between the engagement component and the respective divided gear wheel can be compensated. The smaller helix angle a is chosen, the greater would be the required velocity of the axial movement Ua and therefore the force, applied by an actuator to move the engagement component axially, increases.

But even if angle a is zero, as a result of the small inertia of inner part of divided gear wheel and the existence of a soft elastic element that deforms initially, a smooth engagement can be achieved.

The helical means may comprise at least one helical groove and the engagement component may comprise at least one helical arm, being guided in the helical groove.

Corresponding engagement means may be arranged at the helical arm, preferably at a distal end thereof, and may be adapted to engage with an engagement means provided on an inner circumferential surface of the inner part of the divided gear wheel.

The helical groove(s) and helical arm(s) provide for the helical guiding. In particular, the helical groove(s) may be integrally formed within the assigned shaft. Further, the engagement component comprising helical arm(s) may be assigned to multiple divided gear wheels. This is, as the helical arm(s) and the corresponding engagement means can be pushed through a first divided gear wheel, which runs freely on the shaft and can engage a second consecutive divided gear wheel. The number of gear wheels the engagement component may be assigned to depends on the length of the helical arm(s) and the distance from center to center along the assigned shaft between the respective divided gear wheels. As the engagement component may be assigned to multiple divided gear wheels, gear ratio changing is facilitated, as only a single engagement component has to be axially moved.

The helical means may comprise at least one helical tooth on an outer circumferential surface and the engagement component may comprise a bushing portion having at least one corresponding helical tooth provided on an inner circumferential surface. A corresponding engagement means may be arranged at the bushing portion and may be adapted to engage with the engagement means of the inner part of the divided gear wheel, wherein the engagement means are preferably provided on an outer circumferential surface and/or a front face of the inner part of the divided gear wheel. The number of portions of the inner part of the divided gear wheel can be bigger to facilitate engagement.

This design allows to assign a separate engaging means to every free divided gear wheel. Thereby, the free divided gear wheels can be provided on both, the input and output, shafts. Thus, the automated power transmission system can be provided with reduced length dimensions.

In an alternative embodiment, gear ratios of the power transmission system may be defined by two divided gear wheels. One of these divided gear wheels is a free gear wheel, wherein the other one is a fixed gear wheel. Providing both gear wheels of a gear ratio as divided gear wheels, allows a prolonged time for engagement / disengagement. Particularly, the divided gear wheels can compensate a larger difference in angular velocity between the engagement component and the divided gear wheel to be engaged and therefore the engagement component can be less accelerated.

The longer, softer elastic element has a spring constant that permits negligible deformation between inner/outer part regardless of whether the components accelerate or decelerate or rotate with the same angular speed when the divided gear wheel is not engaged, so that a very small elastic constant is required. Because the engagement component engages with the inner part of the divided gear wheel and due to the fact that the inertia of the inner part is very small and the elastic constant of the softer elastic element is negligible, a smooth engagement can achieved even without comprising a helix angle.

Generally, the power transmission system can comprise an additional set of gear wheels provided upstream the first gear ratio, to reduce the engines revolutions. Further, the power transmission system may comprise a further additional set of gear wheels provided downstream the last gear ratio of the power transmission system, i.e. at the end of the output shaft for multiplying the output revolution. The gear ratio of these additional upstream and/or downstream set of gear wheels can be chosen according to the intended field of application. Accordingly, the gear ratio i may be greater, equal or smaller than 1.

The power transmission system may comprise at least one additional gear wheel that is supported by the input shaft and/or the output shaft, wherein the additional gear wheel preferably engages with a gear wheel of a planetary gear. Particularly, the automatic power transmission can be combined with any known gear.

Further, the power transmission system may comprise a sequential shift actuator, adapted to axially move the at least one engagement component to change a gear ratio. The sequential shift actuator may be designed so that only one free divided gear wheel is in engagement with the assigned shaft (after a finished gear ratio changing action). Accordingly, the shift actuator may simultaneously axially move several engagement components. Thus, a sequential gear ratio changing can be achieved.

The actuator may be a mechanical, a hydraulic, an electric or a pneumatic actuator, or 10 the like. The actuator may be adapted to push (or pull) the engagement component with different axial velocities (depending on the needs / matching the needed Dw) resulting in smooth engagement between the concerning parts.

The power transmission system may further comprise a control unit that is adapted to command a gear ratio changing action. The control unit may be fully automatic, so as to operate the engine at a desired operating point, and/or the control unit may forward user commands so as to allow the user to command a desired gear ratio.

The objects are further at least partly achieved by a method for operating a power transmission system, the method comprising the following steps: Rotating the input shaft and transferring power to the output shaft by means of a first gear ratio. Commanding a gear ratio changing action from a first gear ratio to a second gear ratio. Axially moving an engagement component for engaging a second gear ratio and thereby disengaging the inner part of the divided gear wheel of the first gear ratio from the torque proof fixing with the shaft and engaging the inner part of the divided gear wheel of the second gear ratio, thereby torque proof fixing said inner part with the shaft, wherein the inner part of the divided gear wheel of the second gear ratio is angularly deflected with respect to the outer part and loads the elastic element. Rotating the input shaft and transferring power to the output shaft by means of the second gear ratio.

Depending on the design of the engagement component(s) either one engagement component has to be moved, i.e. if the engagement component is assigned to multiple divided gear wheels, or at least two engagement components have to be moved upon a gear ratio changing action, i.e. if the engagement components are assigned to a respective single divided gear wheel. In this case a first engagement component engages the divided gear wheel to be engaged and a second engagement component disengages the actually engaged divided gear wheel. As a result, at the end of the gear ratio changing action only one divided (free) gear wheel is engaged.

The objects are further at least partly achieved by an automotive vehicle comprising a divided gear wheel or a power transmission system as described above.

As mentioned before, the use of the power transmission system can be extended to other automotive vehicles, besides wheeled vehicles. For example the power transmission system can be adapted in order to be incorporated in a motor vessel. In this scenario, the power transmission system is modified in order to comprise only a forward and a reverse gear.

The innovative features of the proposed invention (i.e. a transmission element comprising at least one set of two elastic elements with the previously mentioned features and characteristics) are also adopted in this configuration.

For example a bevel pinion can be provided as an input gear wheel and two bevel gear (one assigned to the forward gear and one to the reverse gear) can be provided as output gear wheels with the two bevel gears meshing with the bevel pinion.

The bevel gears (transmission elements) can be provided as divided gear wheels according to the previously mentioned characteristics.

Alternatively the engagement component (transmission element), by the movement of which a gear changing action is achieved, can comprise an inner and an outer part that are connected with at least one set of two elastic elements with the layout of the engagement component in respect and in accordance to the previously described layout divided gear wheel, with the two having the same operational characteristics.

The transmission elements (either a divided gear wheel or an engagement component) comprise at least one set of two elastic elements with the two elastic elements comprising a first elastic element and a second elastic element.

Preferably, the first elastic element of the transmission element comprises a lower suspension rate than the second elastic element. If multiple elastic elements are used, the first elastic element comprises the lowest and the last elastic element, i.e. the second elastic element, comprises the highest suspension rate. The elastic elements in between the first and the last elastic element have an ascending suspension rate, wherein the next elastic element after the first elastic element would have a higher suspension rate than the first elastic element and a lower suspension rate than the following elastic element. Further, the suspension rate of the elastic element with the highest suspension rate, i.e. the second elastic element, may be adopted to the maximum torque provided by the motor.

Nevertheless, if the transmission element comprises multiple first and/or second elastic elements, those first elastic elements comprise the same suspension rates and those second elastic elements comprise the same suspension rates, wherein the suspension rates of the first elastic elements differ from the suspension rates of the second elastic elements.

However, independent of the exact arrangement of the elastic elements it can be said that the elastic element with the lowest suspension rate is more responsible for a soft and smooth engagement of the transmission elements, wherein the elastic element with the highest suspension rate is more responsible for power transmission. The elastic element with the smaller suspension rate may only handle less than 0.5% of the maximum occurring load. Thus, due to the existence of elastic elements with very low and high suspension rates, the engagement of the transmission elements with another transmission element is achieved by the elastic elements with low suspension rates, wherein the stiffer elastic elements, i.e. the elastic elements with higher suspension rates, transfer the significant load. For the engagement of two transmission elements, e.g. the engagement of a gear wheel and a selector, it is not mandatory that both transmission elements comprise elastic elements and/or are designed according to the invention.

As mentioned before the elastic elements are received in compartments formed by the inner and the outer parts of the transmission elements. Each compartment can house one or more elastic elements.

If there are multiple elastic elements arranged within one compartment, the first elastic element has the greatest length and the last spring element has the smallest length. The spring elements arranged between the first and the last spring element have a longer length one after the other, so that the second spring element would be the second longest spring element and thus longer than the last and shorter than the first. There may also be compartments comprising at least two elastic elements that are not partially arranged within each other even though they are arranged in the same compartment. In addition, the elastic elements may be held by supports, wherein the supports may comprise at least one recess. If the elastic elements are not arranged within each other, one elastic element may be held by the first part of the support, wherein additional elastic elements may be held by the recessed part of the support.

In a preferred embodiment, the at least one first and the at least one second elastic elements are spring elements. Alternatively, the at least one first elastic element may be provided by a spring element and the at least one second elastic element may be provided by a rubber element such as a rubber block. Regardless of which elastic element is used, the elastic elements always comprise different suspension rates and different lengths as described above.

According to a preferred embodiment of the present invention, the first elastic element, i.e. the elastic element with the lowest suspension rate, is preloaded. When the elastic element comprises a spring arranged within a divided gear wheel, for example a torsional spring, the spring is preloaded so that:

Where T _pre is the preloaded torque of the spring, J is the moment of inertia of the inner part of the divided gear wheel, i.e. the first part of the divided gear wheel, max is the maximum angular acceleration/deceleration that can be achieved by the inner part of the divided bevel gear and Tf is the torque created by friction forces between the inner part and the assigned shaft.

The preloaded spring is adapted in order to have negligibly deformed first elastic element before the engagement, regardless if the components accelerate, decelerate or both rotate with a constant angular velocity. As a result when the divided gear wheel is not in engagement, it stays in a neutral position with the first spring element being negligibly deformed, despite any occurring acceleration or deceleration of the divided gear wheel parts, due to the existence of the preloaded spring.

If the so-called neutral position occurs without the first elastic element being preloaded a higher suspension rate, in comparison to the suspension rate of the preloaded spring, has to be adopted.

In a preferred embodiment, the at least one compartment comprises at least one damping element. Therefore, the number of damping elements may refer to the number of compartments. Further, the at least one damping element may be comprised by the supports, i.e. the inner or the outer supports. The at least one damping element may also be arranged on another component. Regardless of the position of the at least one damping element, the damping element is provided to damp the recoil or kickback that occurs when the transmission element is disengaged from another transmission element, wherein at least one transmission element is designed according to the invention. This recoil or kickback may lead to a collision of the inner and outer parts.

Alternatives to the bevel gear assembly used in motor vessels are also possible, where gears instead of bevel gears are adopted.

Therefore, a gearbox according to the present invention comprises at least one drive shaft, at least one drive wheel coupled to the at least one drive shaft, an output shaft, at least one selector coupled to the output shaft or the at least one drive shaft, and at least one gear wheel, wherein the at least one gear wheel and/or the at least one selector are transmission elements according to the invention. The drive shaft is coupled to an engine and therefore receives power. The output shaft forms the output side. The output side might be a propeller of a boat. The selector is used to engage the at least one gear wheel as defined above to the output shaft so that a power transmission between the drive shaft to the output shaft is realized via the drive wheel, the gear wheel and the selector.

Typically the at least one gear wheel is in constant engagement with the at least one drive wheel or with at least one other gear wheel. Thus, by coupling the selector located on the output shaft to the gear wheel, the above described power transmission between the drive and the output shaft can be realized.

The drive wheel is preferably given by a bevel pinion. For a functioning transmission system, the gear wheel must be adapted to the drive wheel or vice versa. Hence, if a bevel pinion forms the drive wheel, the divided gear wheel must be given by a bevel gear wheel. Other types of gear wheels may be used. Further, also the gear wheel must be adapted to the selector or vice versa. Thus, if a dog clutch type selector is given, the gear wheel needs to comprise respective coupling elements.

In a preferred embodiment the rotational axis of the at least one gear wheel and the rotational axis of the drive wheel form a 90° angle. Different angles may be realized using different gear and drive wheels.

Preferably, the selector comprises first coupling elements for rotationally coupling and/or de-coupling with corresponding first coupling elements of the at least one gear wheel and/or comprises second coupling elements for rotationally coupling and/or de-coupling with corresponding coupling elements of the output shaft. The number of coupling elements intended for mutual coupling and/or de-coupling may differ, e.g. the first coupling elements of the selector may be less than the first coupling elements of the gear wheel. The coupling elements may be formed by cavities or protrusions. Thus, if the first coupling elements are for example formed by protrusions and may be less than the second coupling elements that are for example formed by cavities, there may be a greater number of coupling possibilities. The same applies of course also vice versa.

As mentioned previously, the selector may be axially or helically movable along the assigned shaft and is guided by guiding means that may be arranged linearly or helically.

In the case of helical movement of the selector, the shifting mechanism would have to secure the engagement of the two components with the help of a securing mechanism (e.g. a worm gear mechanism, a hydraulic mechanism etc.).

In addition, the selector may be a dog clutch type selector. Such a dog clutch type selector may comprise teeth or other engagement means which can be coupled with engagement means of the gear wheel. Thus, by engaging the selector, power transfer may be achieved. If the gearbox comprises two gear wheels, the selector may be engaged with one of the gear wheels to provide a rotation of the assigned shaft in one direction and may be engaged with the other gear wheel to provide rotation of the assigned shaft in an opposite direction. The selector may be arranged concentrically to the output shaft.

In addition or as an alternative, at least one sensor for measuring the angular velocity of the drive wheel and/or the at least one gear wheel and/or the output shaft and/or the drive shaft and/or the selector is arranged within the gearbox. By using the sensor information, the throttle may be adjusted in order not to experience stalling. Thus, the throttle may be adjusted automatically in relation to the sensor information. The sensor data can also be used for monitoring systems or the like.

An alternative where the gear transmission elements comprise the features of the proposed innovation instead of the engagement component / gear selector is also possible.

In this alternative, the a preferred embodiment will comprise : a drive shaft, supporting one drive gear wheel, torque proof fixed with the shaft; an output shaft, supporting two transmission elements according to the invention, e.g. two divided gear wheels, wherein each of the two transmission elements constantly meshes with the provided drive gear wheel, thereby defining a forward and a reverse gear ratio, wherein divided gear wheels are adapted to freely rotate when not engaged with the output shaft; and one engagement component/dog clutch type selector, that is assigned to the output shaft and assigned to both the divided gear wheels, wherein the engagement component/dog clutch type selector is positioned concentrically to the output shaft, torque proof fixed with the output shaft, arranged axially movable along the output shaft in order to select forward or reverse gear ratio, adapted to engage the inner part of the divided gear wheels and thereby torque proof fixing the inner part with the output shaft.

Another alternative may comprise an output shaft, supporting a torque proof fixed with the output shaft gear wheel; two drive shafts, each supporting a torque proof fixed with the drive shaft drive gear wheel, and a divided gear wheel as described above, wherein each of the two divided gear wheels constantly meshes with the provided gear wheel, thereby defining a forward and a reverse gear ratio, wherein divided gear wheels are adapted to freely rotate when not engaged with the assigned drive shafts; and an engagement component/dog clutch type selector, that is assigned to each of the respective drive shafts and assigned to each of the divided gear wheels, wherein the engagement component/dog clutch type selector is positioned concentrically to each of the respective drive shafts, torque proof fixed with each of the respective drive shafts, arranged axially movable along each of the respective drive shafts in order to select forward or reverse gear ratio, adapted to engage the inner part of the divided gear wheels and thereby torque proof fixing the inner part with the respective drive shaft.

Preferably, a method for operating a power transmission system for a motor vessel may comprise the following steps: rotating drive shaft and transferring power to output shaft by means of a forward gear ratio; performing a gear ratio changing action from a forward gear ratio to a reverse gear ratio; axially moving the respective engagement component/dog clutch type selector and thereby disengaging the inner part of the divided gear wheel of the forward gear ratio from the torque proof fixing with the assigned output shaft or the assigned drive shaft, and engaging the inner part of the divided gear wheel of the reverse gear ratio, thereby torque proof fixing said inner part with the assigned output shaft or the assigned drive shaft, wherein the inner part of the divided gear wheel of the second gear ratio is angularly deflected with respect to the outer part and each set of two elastic elements is being loaded as a result of this deflection; transferring power to the output shaft by means of a reverse gear ratio. As an alternative the method comprises the following step, wherein during axial moving the at least one engagement component/dog clutch type selector is guided by helical means and rotates in relation to the assigned output shaft or to the assigned drive shaft to compensate the difference in angular velocity at the beginning of the gear ratio changing action between the assigned output shaft or the assigned drive shaft and the divided gear wheel, to be engaged, of the second gear ratio.

Furthermore, a boat with an inboard / outboard motor may comprise the above described at least one divided gear and/or a power transmission. From the above it is clear that the alternatives of the proposed invention are many and many applications fall under the scope of the invention.

A power transmission system according to the proposed invention comprises transmission elements (divided gear wheels or engagement components), with a gear changing action taking place by moving at least one engagement component and engaging a gear wheel.

In any case, at least one of the components that are being engaged has to be a transmission element according to the invention.

The basic principle of the invention is that an inner and an outer part of a transmission element are connected with at least one set of two elastic elements.

As it is obvious between the inner and the outer part, intermediate parts, having analogous formation to the inner and outer parts, can be included with each radially consecutive part being connected to the previous and/or to the following part by at least one set of two elastic elements. Each set of two elastic elements is positioned in a way that, the first elastic element consisting the set of two elastic elements is initially deformed upon deflection of either the at least one inner part or the at least one outer part with the deformation of the second elastic element consisting the set of two elastic elements, following after the completion of the engagement of the inner part with the assigned shaft or of the outer part with the assigned gear wheel, with said deformation of a second elastic element being accompanied by a simultaneous and continuing deformation of the first elastic element, wherein the first elastic element and the second elastic element consisting the set of two elastic elements of each set of two elastic elements have different spring constants in relation to each other, with the spring constant of the first elastic element being smaller than the spring constant of the second elastic element.

Description of preferred embodiments

In the following, preferred embodiments of the present invention are described with respect to the accompanying figures:

Figure 1 gives a schematic illustration of individual components of a transmission element;

Figure 2 gives a schematic illustration of individual components of an alternative transmission element; Figure 3 gives a schematic illustration of individual components of an alternative transmission element;

Figure 4 gives a schematic illustration of individual components of an inner part of a transmission element accompanied by an assigned shaft and an engagement component; Figure 5 gives a schematic illustration of a power transmission system ;

Figure 6 gives a schematic illustration of individual components of a power transmission system;

Figure 7 is a schematic cut view of a power transmission system; Figure 8 to 10 give a schematic illustration of a gear ratio changing action sequence; Figure 11 to 13 give a schematic illustration of a gear ratio changing action sequence;

Figure 14 to 16 give a schematic illustration of a gear ratio changing action sequence; Figure 17 to 21 gives a schematic illustration of a gear ratio changing sequence;

Figure 22 gives a schematic illustration of an alternative power transmission system;

Figure 23 is a schematic cut view of an alternative power transmission system;

Figure 24 is a schematic cut view of an alternative power transmission system;

Figure 25 is a schematic perspective exploded view of a dog clutch of a power transmission system Figure 26 gives a schematic illustration of individual components of an alternative power transmission system;

Figure 27 gives a schematic illustration of an alternative power transmission system;

Figure 28 is a schematic cut view of an alternative transmission element;

Figure 29 is a schematic cut view of an alternative transmission element;

Figure 30 is a schematic cut view of an alternative transmission element; Figure 31 gives a schematic illustration of individual components coupled to the transmission element of the previous figure; Figure 32 gives a schematic illustration of individual components of an alternative transmission element;

Figure 33 gives a schematic illustration of individual components of an alternative transmission element; Figure 34 gives a schematic illustration of individual components of an alternative transmission element;

Figure 35 to 39 gives a schematic illustration of a gear ratio changing sequence;

Figure 40 is a schematic cut view of an alternative power transmission system;

Figure 41 is a schematic cut view of an alternative power transmission system;

Figure 42 is a schematic perspective view of an alternative power transmission system; Figure 43 is a schematic view of an alternative power transmission system ;

Figure 44 is a schematic cut view of an alternative power transmission system;

Figure 45 is a schematic cut view of an alternative power transmission system;

Figure 46 gives a schematic illustration of individual components of an alternative power transmission system;

Figure 47 gives a schematic illustration of individual components of an alternative power transmission system; Figure 48 is a schematic detail illustration of the engagement means of individual parts of a power transmission system according to the previously mentioned configurations; Figure 49 is a schematic detail illustration of the engagement means of individual parts of a power transmission system according to the previously mentioned configurations.

In Figure 1 , a schematic illustration of individual components of a transmission element are presented.

More specifically the transmission element presented is a gear wheel, the so called divided gear wheel.

An exploded view of a divided gear wheel with one set of two elastic elements is presented. The elastic elements in this configuration are spring elements.

More specifically the elastic element 130 is the first elastic element and the elastic element 140 is the second elastic element.

The first elastic element 130 and the second elastic element 140 consist the at least one set of two elastic elements that are positioned within a transmission element according to the present invention.

As can be seen, divided gear wheel 100 is consisted by an inner part 110 and an outer part 120, sharing a common rotational axis. The outer part 120 comprises a gear teething 122 adapted to transfer torque to another gear wheel.

Gear teething 122 can comprise many of the know gear teething (e.g. bevel gear teething, helical gear teething etc.) with a corresponding change in the gear teething of the meshed gear wheel.

The inner part 110 is supported on a shaft that can either be an input shaft or an output shaft of a power transmission system. The gear wheel that meshes with the presented transmission element 100 will form a gear ratio of a power transmission system.

The first elastic element 130 is provided as initially compressed upon deflection of the inner or outer parts 110, 120 and comprises a lower spring constant in relation to the second elastic element 140.

Therefore the first elastic element 130 is provided as a“softer” elastic element and the second elastic element 140 is provided as a“stiffen elastic element (both the terms“softer” and“stiffer” are used in comparison of the two elastic elements).

The first elastic element 130 is in constant contact between the inner part 110 and the outer part 120 and is housed within a compartment formed by the inner elastic element support 111 and the outer elastic element support 121 ,

By the angular deflection of either the inner part 110 or outer part 120 the first elastic element 130 is initially compressed and as the deflection progresses, the second elastic element 140 begins to compress with a continuing compression of the first elastic element 140.

The elastic elements 130, 140 are provided with the first elastic element 130 having an increased length in comparison to the length of the second elastic element 140.

Additionally the elastic elements 130, 140 in this illustration are presented as coaxially positioned, with the first elastic element 130 positioned within the second elastic element 140 which has an increased diameter in order to house the first elastic element 140.

This positioning of the two elastic elements 130, 140 are exemplary and many other can be adopted. In addition both of the elastic elements 130, 140 are positioned within a single compartment. In alternative configurations each elastic element can be positioned in separate compartments but the elastic elements 130, 140 will always positioned in a way that the first elastic element 130 (which is “softer” and “longer” in comparison to the second elastic element 140) is initially compressed and the compression of the second elastic element 140 will follow, as the angular deflection of the inner part 110 or the outer part 120 progresses.

It is worth mentioning that the presented configuration comprises one set of two elastic elements, but this is not restrictive since additional elastic elements can be added.

In any case among the chosen number of elastic elements at least one first elastic element and at least one second elastic element will be present, with the chosen elastic elements obeying the principles of the invention. Furthermore the elastic elements 130, 140 have a completely different role in relation to each other.

The role of the first elastic element 130 is to assist with an easy and smooth engagement and to provide adequate time in order the engagement of the inner part 110 to be completed (the engagement takes place by the provision of an engagement component).

In contrast, the role of the second elastic element 140 is to transfer the significant amount of the occurring load. As a person skilled in the art understands, the first elastic element 130, also transfers some amount of the occurring load, but it is not significant in comparison to the load that is transferred via the second elastic element 140.

The inner support 111 is received within the outer support 121 , which has a recess for that reason. As it is obvious the particular shape of the inner support 111 and the outer support 121 can vary, with the two being shaped in relation to each other.

The first elastic element 130 can be provided as a preloaded spring in order to maintain the inner part 110 and the outer part 120 in a so called“neutral position”.

In that case, damping elements 128 have to be provided in order to damp the recoil of the parts when the transmission element stops being engaged.

Engagement means 115 are positioned in the inner circumferential surface of the inner part 110 of the transmission element 100 (in an alternative, engagement means may be provided on the front face of the inner part of the transmission element). By the interaction of the engagement means 115 with the engagement means of an engagement component, the inner part 110 is torque proof fixed to the assigned shaft of a power transmission system and when the elastic elements 130, 140 which are positioned inside the transmission element are fully loaded, both the inner part 110 and the outer part 120 will rotate with the same angular velocity.

Bearings 400 provided in between the assigned shaft and the inner part 110 and bearings 500 are provided between the inner part 110 and the outer part 120. Moreover, the inner ring of the bearings 400 is shaped accordingly in order to permit the engagement of the inner part 110 by the engagement component.

The engagement means 115 may be provided in greater numbers than the engagement means of the engagement component in order to have easier engagement.

In figure 2 an alternative divided gear wheel 100 (transmission element) is presented, with the engagement means 115 being positioned on the front face of the inner part 110 instead of the inner circumferential surface of said part.

The layout is similar to the previous picture with the bearings being omitted.

The alternative positioning of the engagement means 115 demands for a respective change in the positioning of the engagement means of the engagement component.

Furthermore the engagement means 115 can have any suitable shape or form (with a respective change in the shape and form of the engagement means of the engagement component) and can be shaped as protrusions, recesses or a combination of the two.

In this illustration the engagement means 115 have pointed ends in order to assist the engagement.

In figure 3 a schematic illustration of the inner part 110 and the outer part 120 of the divided gear wheel 100 (transmission element) in a perspective layout can be seen.

In this depiction, the engagement means 115 of the inner part 110 of the divided gear wheel 100 can be seen.

As mentioned before the engagement means 115 are in accordance with the engagement means (teeth) of the engagement component.

The engagement means 115 of the inner part 110 are presented as recesses since the engagement means (teeth) of the engagement component have been selected to be protrusions.

In addition the number of recesses and protrusions (or vice versa, or a combination of both in alternative designs) between the two engaging components are in accordance to each other (As a person skilled in the art understands the number of engagement means 115 does not have necessarily to be equal to the number of engagement means (teeth) of the engagement component.

Furthermore as mentioned before the engaging surfaces are in relation to each other.

If, for example, the engaging surfaces of the engagement means (teeth) of the engagement component are perpendicular, in relation to the face of the engagement component, the engaging surfaces 116 of the inner part 110 of the divided gear wheel 100 will again be perpendicular in relation to the face of the inner part 110.

In addition in this exemplary configuration elastic element support 11 1 of the inner part 110 of the divided gear wheel 100, is positioned in between the two elements consisting elastic element support 121 of the outer part 120 of the divided gear wheel 100, and as a result the two parts (inner part 111 and outer part 120, do not collide to each other).

It is going without saying that other forms for both spring supports 111 , 121 can be adopted. Additionally the elastic elements are not presented in this figure only for visual purposes. It is going without saying that the transmission elements always comprise elastic elements.

It is going without saying that in the one compartment a preloaded soft first elastic element may be adopted and in the other compartment the stiffer elastic element may be adopted wherein the two ends of the first softer elastic elements are in constant contact with the inner/outer supports and the ends of the second elastic element will be in contact with the supports after a certain compression of the first elastic element due to the angular deflection of the parts.

In figure 4, individual components of a power transmission system can be seen. More particular the figure presents an engagement component 200, an assigned shaft 20 (for example an output shaft), and an inner part 110 of a divided gear wheel (transmission element). As can be seen in more detail, engagement component 200 is consisted by a bushing portion 201 and at least one arm 210 extending from the bushing portion 201 and, provided at the distal end, corresponding engagement means 220, which are adapted to engage with the engagement means 115 of the inner part 110 of the divided gear wheel (transmission element).

Engagement component 200 is constantly engaged to the assigned shaft 20 (for example with the help of splines on the inner circumference of the bushing portion 201 ) but can be axially moved (by actuating means).

It is guided by guiding means 21 (linear as presented or helical in an alternative) integrally formed to the shaft 20 and engagement means 220 adapted to engage with the engagement means 115 of the inner part 110 of the divided gear wheel 110.

Engagement means 220 of the engagement component 200, have a length suitable for engaging two consecutive inner parts 110 upon a gear changing action.

In other words when a gear changing action is allowed by the CPU (as previously described), the engagement means 220 will be (at one point) half engaged to the previous gear ratio and half engaged to the following gear ratio.

By this it is obvious that the positioning of two consecutive divided gear wheels is in accordance to the length of the engagement means 220.

In addition the engagement means 115 are not positioned on the front face of the inner part 110 of the divided gear wheel, but are on the inner circumference of the inner part 110.

In this alternative the number of engagement means 115 do not have necessarily be in relation to the engagement means 220. For example the number of engagement means 115 provided by the inner part 110 can be greater than the engagement means 220 provided by the engagement component 200, resulting in an easier engagement between the two components.

In figure 5 a power transmission system 1 is presented. The power transmission system 1 comprises an input shaft 10, which supports input gear wheels 300a, 300b, and an output shaft 20, which supports output gear wheels 100a, 100b.

Gear wheels 100a meshes with gear wheel 300a and therefore defines a first gear ratio and gear wheel 100b meshes with gear wheel 300b and therefore defines a second gear ratio. The power transmission system 1 presented comprises two gear ratios but as it is obvious, more can be added.

Gear wheels 100a, 100b are provided as divided gear wheel (transmission elements) as previously described with the characteristics and the layout of a divided gear wheel as described in detail above.

Input gear wheels 300a, 300b are constantly engaged to the assigned input shaft 10 and divided gear wheels 100a, 100b are engaged to the assigned shaft 20 by interacting with engagement component 200.

The divided gear wheels 100a, 100b are free to rotate when they are not engaged, not transferring any torque. In order to transfer torque a divided gear wheel 100 has to be engaged by the engagement component 200 which is torque proof fixed to the assigned shaft but has the ability to be moved axially.

The engagement component 200 is assigned to multiple divided gear wheels but as it is obvious in an alternative configuration each divided gear wheel can be assigned to a single engagement component 200.

The axial movement of the engagement component 200 by according actuating means, engages (or disengages) the inner part 110 of the divided gear wheels 100, and therefore a gear ratio is selected.

In the presented configuration, a gear ratio is consisted by one gear wheel and one divided gear wheel. Alternatively, each gear ratio could be consisted by two divided gear wheels with the one being torque proof fixed to the assigned shaft (via a constantly engaged inner part) and the other being engageable to the assigned shaft, being engaged by the engagement component 200.

Therefore each gear ratio is defined by a set of gear wheels in which at least one gear wheel is a divided gear wheel as described above. In every gear ratio one gear wheel is engageable (engaged upon interaction with the engagement component 200) to the assigned shaft and the other is constantly engaged to the assigned shaft.

As mentioned before the engageable gear wheel can rotate freely, without transferring torque to the assigned shaft when it is not engaged (to the assigned shaft). As a person skilled in the art understands the engageable gear wheel is always a divided gear wheel.

In this configuration the engagement component 200 it is, exemplarily, positioned before the gear ratio“b”, as defined by the interaction of gear wheel 300b and divided gear wheel 100b.

Engagement component 200, is axially pushed (or pulled) by according actuating means (with the assistance of a CPU as previously described) and is guided by guiding means 21 , which are integrally formed to the shaft 20 which are (exemplarily) presented as linear grooves (in yet another alternative the grooves can be helical with an analogous operation as previously described, i.e. additional angular velocity upon axial displacement).

By the axial push or pull of the engagement component 200, a divided gear wheel is engaged or disengaged (via the engagement of the inner part 110).

In figure 6 wherein the power transmission system 1 comprises a divided gear wheel 100 which comprises two sets of two elastic elements can be seen.

Each set of two elastic elements is consisted by a first elastic element 130 and a second elastic element 140 with the elastic elements 130, 140 obeying the principles of the innovation as described in detail above.

The configuration is similar to the previous embodiment with each gear ratio being consisted by one engageable divided gear wheel 100 and one gear wheel 300.

The presented configuration comprises only one gear ratio for exemplary reasons. It is going without saying that more can be added.

In particular, the engageable divided gear wheel 100 of each gear ratio, comprises two sets of two elastic elements with a corresponding change in the form of the inner parts 110 and the outer parts 120 of the divided gear wheels 100.

In this embodiment the guiding means 21 of the output shaft 20, are presented having a helix angle equal to zero and therefore the guiding means are straight and as a result the engagement component 200 does not have an additional angular velocity upon axial movement. As it is obvious the engagement component 200 is reshaped accordingly in order to suit the guiding means.

In order to axially move the engagement component 200, an actuator coupling member 205 is provided.

Furthermore inner bearings 400 (one on each face of the divided gear wheel 100) positioned in between the inner part 110 and the assigned output shaft 20, and outer bearings 500 positioned in between the inner part 110 and the outer part 120 are provided in order to assist the movement between the parts.

The engageable divided gear wheels 100 are provided as being supported by the output shaft 20. This is not restrictive since an engageable divided gear wheel or a divided gear wheel or a transmission element in general can be positioned in an input or in an output shaft or in both of the shafts. As it is obvious when a shaft supports an engageable divided gear wheel, the engagement component that engages with the engageable divided gear wheel, will also be supported by the same shaft.

Figure 7 is a schematic cut view illustration of a gear ratio of a power transmission system 1 , defined by a divided gear wheel 100b comprising two sets of two spring elements (elastic elements) in two elastic element compartments (spring compartments), supported by the output shaft 20, engaged with a gear wheel 300b supported by the input shaft 10.

The divided gear wheel 100b is consisted of an outer part 120b and an inner part 110b connected to one another by means of four springs 130b1 , 130b2, 140b1 , 140b2. The inner part 110b and the outer part 120b have a common rotational axis, and the inner part 110b is at least partially arranged within the outer part 120b.

Further since two sets of two elastic elements (springs) 130b1 , 130b2, 140b1 , 140b2 are adapted to couple the inner part 110b and the outer part 120b, the inner part 110b is angularly deflectable with respect to the outer part 120b and vice versa.

The outer part 120b of the divided gear wheel 100b has a gear teething 122b on its outer circumference, able to transfer rotational force and/or torque. This gear teething 122b is constantly meshing with the gear teething 305b of the gear wheel 300b which is supported by the input shaft 10 and is constantly engaged with the shaft 10.

The inner part 110b is not constantly engaged with the output shaft 20, but can be torque proof engaged with the shaft only when the engagement means of the inner part 110b interact with the engagement means (teeth) of the engagement component.

Both inner part 110b and outer part 120b have elastic element supports 111 b, 121 b, supporting the four springs 130b1 , 130b2, 140b1 , 140b2 which are preferably integrally formed with the outer part 120b or the inner part 110b, respectively.

Therefore the inner part 110b comprises the elastic element support 111 b and the outer part comprises the elastic element support 121 b.

The four springs 130b1 , 130b2, 140b1 , 140b2, are received in elastic element compartments, formed by the inner part 110b and the outer part 120b.

In this exemplary illustration, two sets of two elastic elements, housed in two elastic element compartments, are adapted as elastic elements, distributed around the inner circumference of the outer part 120b.

Each set of spring elements is consisted by two spring elements and the first spring element 130b1 , 130b2 is positioned concentrically to the second spring element 140b1 , 140b2 which has increased diameter in relation to the first spring element 130b1 , 130b2. The concentric positioning of the first spring element 130b1 , 130b2 and the second spring element 140b1 , 140b2 is not restrictive and many others can be adopted with the adopted elastic elements of the divided gear wheels obeying the principles of the invention.

In addition the first spring element 130b1 , 130b2 protrudes out of the second spring element 140b1 , 140b2 on a front face and the first spring element 130b1 , 130b2 has a lower spring constant than the second spring element 140b1 , 140b2.

Since the first spring elements protrude out of the second spring elements on a front face it is obvious that they are provided as“longer” elastic elements in relation to the second elastic elements which are provided as“shorter” elastic elements. Due to this difference in length the first elastic elements are initially compressed, with the compression of the second elastic elements following.

This “softer” spring element assists with an easier, smoother engagement/disengagement between the engagement component and the inner part 110b of the divided gear wheel 100b, and provides the needed time in order to fully engage/disengage the engagement component and the inner part 110b of the divided gear wheel 100b.

In the presented exemplary configuration, all of the spring elements 130b1 , 130b2, 140b1 , 140b2 will compress no matter how the rotating components rotate in relation to each other (clockwise or counterclockwise).

Various design approaches can be adapted, always following the basic principle behind the invention, where the spring elements will be lengthened instead of being compressed.

Furthermore additional or fewer sets of elastic elements can be incorporated to the design, with a corresponding redesign of the inner part 110b and the outer part 120b. In any case the minimum number of elastic elements will be two, with the two elastic elements having the characteristics of the first and second elastic elements as presented in the invention and the overall design approach obeying the basic principles of the invention.

The inner part 110b, also comprises engagement means on its front face (and therefore they cannot be seen in the presented section cut) where the engagement means (teeth) of the engagement component, engage and thereby torque proof fixing the inner part 1 10b to the output shaft 20.

The engagement means in this exemplary configuration are on the front face of the inner part 110b. In another alternative configuration the engagement means can be on the inner circumference of the inner part 1 10b of the divided gear wheel 100b.

Both engaging surfaces between the engaging parts will be corresponding to each other. Upon engagement, the inner part 110b and the output shaft 20, will be torque proof engaged. The inner part 110b and the outer part 120b of the divided gear wheel 100b, rotate with the same angular velocity, when the springs 130b1 , 130b2, 140b1 , 140b2 are fully loaded (under the occurring load).

In the presented configuration, a gear ratio is defined by one divided gear wheel 100b and one gear wheel 300b, constantly meshing via gear teeth 122b and 305b respectively.

The divided gear wheel 100b is engageable with the output shaft 20, engaged upon engagement with the engagement means (teeth) of the engagement component.

The engagement means of the inner part 110b an the engagement means of the engagement component are not visible in the presented figure.

The gear wheel 300b is constantly engaged with the input shaft 10 and power can be transferred from one shaft to the other only when the inner part 1 10b of the divided gear wheel 100b, is engaged with the engagement component.

Power is transferred via the selected gear ratio, from the moment the engagement component engages to the inner part 1 10b of the divided gear wheel 100b.

Even when the softer springs compress, a small amount of power is transferred to assigned shaft. The springs 130b1 , 130b2, 140b1 , 140b2 do not have to be fully loaded in order to transfer torque, but upon full load, both inner part 110b and outer part 120b of the divided gear wheel 100b, rotate with the same angular velocity.

It is going without saying that both gear wheels forming a gear ratio can be divided gear wheels, resulting in additional features for the configuration.

In this scenario, both gear wheels will be divided gear wheels but again one gear wheel will be constantly engaged with the assigned shaft and the other will be free to rotate when not engaged, transferring power only upon engagement with corresponding engagement means.

In other words, the inner part of the free to rotate divided gear wheel will be engageable with the shaft and the inner part of the other divided gear wheel forming a gear ratio will be constantly engaged with the assigned shaft.

Figure 8 to 10 give a schematic illustration of a gear ratio changing action sequence, using random numbers and random gear ratios. More particularly there is an upshifting gear ratio changing action from gear ratio“a” to gear ratio“b”. For this example a heavy vehicle (e.g. truck), with the following gear ratios: gear ratio “a” = 6.05, gear ratio “b” = 5.16 are selected and the numbers are integral. It is going without saying that the two gear ratios presented are not the only gear ratios of the automotive power transmission system, but are presented in order to explain the gear changing action.

In this set of figures two gear ratios (four gear wheels in total) are presented with a dog clutch in between them in accordance to the previously mentioned layouts. The divided gear wheels 100a and 100b are supported by the output shaft 20 and the gear wheels 300a and 300b are supported by the input shaft 10.

Each gear ratio is formed by one divided gear wheel 100 and one gear wheel 300, constantly meshing to each other but can transfer torque to the output shaft 20 only when the divided gear wheel 100 is engaged with the output shaft 20 with the help of dog clutch (engagement components 200 are presented as bold lines, one for each gear ratio). As a consequence gear ratio“a” is formed by divided gear wheel 100a and gear wheel 300a and gear ratio“b” by divided gear wheel 100b and gear wheel 200b.

In figure 8 the divided gear wheel 100a is torque proof engaged with the output shaft 20 and gear ratio“a” is selected.

At this moment the divided gear wheel 100b is disengaged and rotates, due to the fact that it is meshing with the constantly engaged (to the input shaft) gear wheel 300b.

As mentioned before the gear wheels 300a and 300b are constantly engaged with the input shaft 10 and the divided gears 100a and 100b can rotate freely when they are not engaged with the output shaft 20 (with the help of the dog clutch), but are torque proof engaged with the output shaft 20 upon engagement.

The input shaft 10 rotates, for example, with 1700 revolutions per minute (rpm) and the output shaft 20 rotates with 281 rpm due to the fact that gear ratio“a” is selected (i.e. dog clutch is engaged to gear ratio“a”).

Divided gear 100b rotates with 330 rpm, but does not transfer torque to the assigned shaft, since is not engaged with the shaft via an engagement component 200b.

The divided gear wheel 100b rotates due to the fact that is constantly meshing with gear wheel 300b, which rotates with 1700 rpm, since is constantly engaged with the input shaft 10.

Springs 150 (set of two elastic elements) are fully loaded in both gear ratios “a” and“b”, but the springs 150a are fully compressed (since gear ratio“a” is selected), and the springs 150b are decompressed (since gear ratio“b” is not engaged with the dog clutch).

In either case (decompression or fully compression) the springs 150 are fully loaded according to occurring load.

The difference between the two conditions is the occurring load that results in the according compression. In the case that the spring 150a is fully compressed, the applied load to the spring is great, resulting in larger deformation/compression.

In gear ratio“b” the spring 150b is, again fully loaded, but not compressed due to the fact that the applied load is minimum as a result of the unengaged, free to rotate divided gear wheel 100b.

As can be seen in figure 9 a gear changing action (from gear ratio“a” to gear ratio “b”) is commanded and after certain processes in the CPU, the engagement component 200b assigned to the divided gear wheel 100b is moved by a shifting mechanism and engages with the inner part.

The engagement component 200a assigned to the divided gear wheel 100a is still engaged with the inner part of the divided gear wheel 100a.

As a consequences both inner parts of the divided gear wheels 100a and 100b are engaged with the output shaft 20 via their assigned engagement components 200 (e.g. dog clutch rings).

Now the inner part of the divided gear wheel 100b, rotates with 281 rpm since is now torque proof engaged with the assigned output shaft 20 due to the dog clutch engagement.

Since the input rotations from the engine is 1700rpm and the outer part of the divided gear wheel 100b rotates with 330rpm, springs 150b inside the divided gear wheel start to compress, but since initially, up till the engagement is completed, only the first “softer” spring element of the springs 150b is compressed, the load transfer is not significant.

As a person skilled in the art understands, as the time passes, the load being borne by the springs 150b inside the divided gear wheel 100b increases and at the same time the load being borne by the springs 150a inside the divided gear wheel 100a decreases.

At this moment, both inner parts of the divided gear wheels 100a, 100b are engaged with the output shaft 20, and therefore power is transferred via both gear ratios“a” and“b”.

As it is obvious, as the time passes, more power is delivered to the output shaft 20 via gear ratio“b” and less via gear ratio“a”. An intermediate moment is presented in figure 9 in which, for example, the inner part of the divided gear wheel 100b rotates with 281 rpm, the outer part of the divided gear wheel 100b rotates with 310rpm and gear wheel 300b rotates with 1600rpm.

In addition the inner part of the divided gear wheel 100a rotates with 281 rpm and gear wheel 300a rotates with 1600rpm.

As can be seen due to the difference in angular velocities between the inner parts of the divided gear wheels 100a, 100b and the angular velocities between their coupled outer parts of the divided gear wheels 100a, 100b, springs 150a decompress and springs 150b compress.

When all of the power from the input shaft 10 is delivered to the output shaft 20 via gear ratio“b” the springs 150a inside the divided gear wheel 100a of gear ratio“a” will be fully decompressed and the disengagement of the inner part of the divided gear wheel 100a can take place.

In figure 10 all of the power is delivered to the output shaft 20 via gear ratio “b”, and as a result springs 150a inside the divided gear wheel 100a are fully decompressed.

The CPU is aware of the nearly fully decompressed springs 150a, due to the fact that corresponding position sensors are adapted, and as a consequence, commands a disengagement action to begin, disengaging the inner part of the divided gear wheel 100a.

Now all of the power is delivered via gear ratio“b”.

The inner part and the outer part of the divided gear wheel 100b rotate with 281 rpm. In addition gear wheel 300b rotates with 1450rpm and so does the gear wheel 300a and the engine. Divided gear wheel 100a is ungagged and therefore free to rotate, rotating with 240rpm due to the meshing with gear wheel 300a.

As can be seen from the above the gear changing action is completed and now the power is transferred via gear ratio“b”, with a continuous, smooth, uninterrupted power transfer from gear ratio“a” to gear ratio“b” and with a corresponding“drop” of rpm to the engine (from the initial 1700 to 1450). In figures 11 to 13 an example for a gear changing action for a heavy vehicle (e.g. truck) is presented and more specifically a downshifting gear changing action (i.e. from gear ratio“b” to a lower gear ratio“a”).

This figures present a downshifting gear changing action with the accelerator pedal pressed.

The configuration is similar to the one described in figures 8 to 10.

As can be seen in figure 11 the inner part of the divided gear wheel 100b is engaged with the output shaft 20 and the divided gear wheel 100a is disengaged and as a result free to rotate.

As a consequence gear ratio“b” is selected and the output is 271 rpm with an input of 1400rpm. Both the gear wheels 300a and 300b rotate with 1400rpm (due to the constant engagement to the input shaft 10).

Springs 150a are fully decompressed and springs 150b are fully compressed. The inner part and the outer part of the divided gear wheel 100a rotate with 231 rpm and the inner part and the outer part of the divided gear wheel 100b rotate with 271 rpm, due to their meshing with gear wheels 300a and 300b respectively.

A gear changing action from the selected gear ratio“b” to the previous gear ratio“a” (downshifting) is commanded by the CPU.

In figure 12 the downshifting action has initiated.

CPU commands the engine to a power cut (idling). As a result springs 150b inside the divided gear wheel 100b start to decompress and a disengagement command (from the CPU) can initiate, in order to disengage the inner part of the divided gear wheel 100b.

As mentioned before CPU acknowledges that the disengagement is completed from the data acquired by the linear position sensors.

At the same time an engagement command (from the CPU) can take place, engaging the inner part of the divided gear wheel 100a with the assigned engagement component 200a and power from the engine is resumed, in relation to the position of the gas pedal. As a result the inner part of the divided gear wheel 100a rotates with 271 rpm.

Since the accelerator pedal is pressed, engine’s revolutions increase (input rpm), and as a result the outer part of the divided gear wheel 100a increases its revolutions until reaching 271 rpm.

Due to that, springs 150a inside the divided gear wheel 100a begin to compress (Initially the first elastic element compresses and after the completion of engagement the second elastic element starts to compress).

In figure 13 the engagement/disengagement has been completed and now both inner part and outer part of the divided gear wheel 100a rotate with 271 rpm and springs 150a inside the divided gear wheel 100a are compressed.

As a consequence the input shaft 10 rotates with 1641 rpm, gear wheels 300a and 300b rotate also with 1641 rpm and both inner part and outer part of the divided gear wheel 100b rotate with 318rpm with springs 150b inside the divided gear wheel 100b being decompressed.

Therefore gear ratio“a” is selected with the divided gear wheel 100a engaged with the assigned output shaft 20 and the divided gear wheel 100b disengaged and as a result free to rotate.

In the next three figures (from 14 to 16) a downshifting gear changing action with the accelerator pedal not pressed (second scenario) is presented. In relation to the first scenario (accelerator pedal pressed) presented in the three previous figures, the direction of compression for the springs 150 inside the divided gear wheel 100 is in a clockwise manner.

As can be seen in figure 14 springs 150 inside the divided gear wheel 200 compress in a clockwise direction. As can be seen springs 150b inside the divided gear wheel 100b are compressed and springs 150a inside the divided gear wheel 100a are decompressed.

In addition both the input shaft 10 and gear wheels 300a, 300b rotate with 1400rpm, both the inner part and the outer part of the divided gear wheel 100a rotate with 231 rpm and both the inner part and outer part of the divided gear wheel 100b rotate with 271 rpm. The CPU commands a gear changing action from gear ratio“b” to gear ratio “a” and as a consequence the engagement of the inner part of the divided gear wheel 100a with the assigned engagement component 200a takes place.

In figure 15 the now engaged inner part of the divided gear wheel 100a rotates with 271 rpm and springs 150a inside the divided gear wheel 100a begin to force the outer part of the divided gear wheel 100a to rotate with more than 231 rpm.

Since the outer part of the divided gear wheel 100a meshes with gear wheel 300a, gear wheel 300a is forced to rotate with more than 1400rpm and so does gear wheel 300b.

In addition gear wheel 300b meshes with the outer part of the divided gear wheel 100b, forcing it to rotate with more than 271 rpm while the inner part of the divided gear wheel 100b rotates with 271 rpm, and as a result springs 150b inside the divided gear wheel 100b start to decompress and a disengagement command (inner part of the divided gear wheel 100b to be disengaged from the assigned engagement component 200b) is given by the CPU.

In figure 16 the engagement/disengagement has been completed and both inner part and outer part of the divided gear wheel 100a rotate with 271 rpm and springs 150a inside the divided gear wheel 100a are compressed.

Input shaft 10 rotates with 1641 rpm, and gear wheels 300a, 300b also rotate with 1641 rpm (due to the meshing with divided gear wheel 100a).

Furthermore both inner part and outer part of the divided gear wheel 100b rotate with 318rpm and springs 150b inside the divided gear wheel 100b are decompressed.

Therefore gear ratio“a” is selected with the divided gear wheel 100a engaged with the assigned output shaft 20 and the divided gear wheel 100b disengaged and as a result free to rotate.

As a person skilled in the art understands, in case springs 150b inside the engaged divided gear wheel 100b are decompressed (third scenario) the operation is the same as the first and second scenarios presented in figures 8E, 9E and 8F, 9F.

Figures 17 to 21 show schematic illustrations of the gradient torque transfer between gear ratio n to gear ratio n+1.

In the demonstration the engagement component is guided by straight guiding means instead of helical (helix angle equal to zero).

Therefore upon axial movement the engagement component rotates with the same angular velocity as the assigned shaft.

This set of figures depicts two divided gear wheels of two consecutive gear ratios n, n+1 with both the divided gear wheels being engageable by an engagement component, and the depiction is a schematic equivalent to the previously explained configurations.

Each engageable divided gear wheel meshes with a corresponding fixed (to the assigned shaft) gear wheel (presented as a tangent circle on top of the divided gear wheels) forming a gear ratio. The fixed gear wheels can either be divided gear wheels or gear wheels as previously mentioned.

As can be seen in figure 17, the set of two elastic elements of gear ratio n is fully compressed and the set of two elastic elements of gear ratio n+1 is fully decompressed.

Therefore gear ratio n is selected and the corresponding free divided gear wheel is engaged.

The divided gear wheel of gear ratio n+1 is not engaged and therefore free to rotate and as a consequence 100% of the torque is transferred to output shaft by gear ratio n.

The term“selected” is used when the“stiffer” elastic elements of a gear ratio, are compressed and the term “engaged” is used when the engagement component interacts with the inner part of the divided gear wheels.

As a consequence a divided gear wheel can be“engaged” but the gear ratio not“selected” (i.e. the“stiffer” elastic elements are not compressed, but the “softer” elastic elements are). In contrast a gear ratio cannot be“selected” without the divided gear wheel of that gear ratio not being“engaged”.

In figure 18 a gear changing action is commanded by the CPU and corresponding engagement component or components are moved.

As a result gear ratio n continues to be selected and engaged and gear ratio n+1 is engaged but not selected since only the“softer” elastic element of the set of two elastic elements starts to compress and provides the time for a complete engagement of the inner part of the divided gear wheel of gear ratio n+1.

When the engagement is completed only about 0.1 % of the torque is transferred to output shaft by gear ratio n+1 (since the“stiffer” elastic element is not compressed at all) with an equal decrease in the transferred torque by gear ratio n.

As can be seen the set of elastic elements of gear ratio n+1 is visually compressed due to the compression of the“softer” elastic element.

In figure 19 both gear ratios n and n+1 are selected and engaged.

As a consequence, the “stiffer” elastic elements of both gear ratios are compressed with the“stiffer” elastic element of gear ratio n+1 beginning to transfer torque to output shaft, with a corresponding decrease in the transferred torque (to the output shaft) by gear ratio n.

For example 80% of the occurring torque is being transferred by gear ratio n and 20% by gear ratio n+1.

As can be seen in figure 20, as time passes more torque is being transferred by gear ratio n+1 and less torque is being transferred by gear ratio n.

As a result the set of two elastic elements of gear ratio n+1 is more compressed and the set of two elastic elements of gear ratio n is less compressed. At the presented stage equal amounts of torque are being transferred by each gear ratio.

Finally in figure 21 , gear ratio n+1 transfers 100% of the torque and gear ratio n is not selected nor engaged with its divided gear wheel rotating freely. The set of two elastic elements of gear ratio n are decompressed and the set of two elastic elements of gear ratio n+1 are compressed.

At this stage the gear changing action is completed and gear ratio n+1 is selected.

In figures 22, 23 an alternative configuration, similar to the above presented configurations is presented.

As can be seen in figure 22 the alternative configuration is pretty much alike to the one presented in figure 5 for example, but in this configuration every gear ratio is consisted by two divided gear wheels 100a, 100a’, 100b, 100b’, with the divided gear wheels 100a’, 100b’ supported by the output shaft 20 and the divided gear wheels 100a, 100b supported by the input shaft 10.

Furthermore the divided gear wheels 100a’, 100b’ are provided as free divided gear wheels and the divided gear wheels 100a, 100b are provided as engaged divided gear wheel, with the inner parts 110a, 110b torque proof engaged with the assigned output shaft 20.

As a consequence each gear ratio is consisted by one engageable free to rotate (when is not engaged with the assigned output shaft 20) divided gear wheel 100a’, 100b’ and one engaged with the assigned input shaft 10 divided gear wheel 100a, 100b.

In addition the guiding means 21 are provided as helical guiding means (instead of the previously described linear) with an according modification in the engagement component 200, that is assigned to the output shaft 20.

As can be seen the engagement component 200 is torque proof engaged with the assigned output shaft 20, axially movable and able to be engaged with the inner parts of the divided gear wheels 100a’, 100b’ depending on the needs.

Upon engagement the inner part (for example the inner part 110a’) of the divided gear wheels 100a’, 100b’ is torque proof engaged with the assigned output shaft 20.

As a person skilled in the art understands, due to the helical guiding means 21 , when the output shaft 20 rotates, an axial (in relation to the main axis of the output shaft 20) force pushes the engagement component 200 towards the next gear ratio, and therefore assisting with the engagement of the engagement component 200 and the assigned inner parts of the divided gear wheels 100a’, 100b’ when upshifting.

In contrast when we want to downshift the method is similar to the previously described one.

Figure 23 depicts a more clear view of the divided gear wheels 100a’, 100b’ of gear ratios“a” and“b” in which the exemplary position of the inner bearings 400a’, 400b’ and the outer bearings 500a’, 500b’ is clearer.

As can be seen inner bearings 400a’, 400b’ (consisted of a set of bearings, one on each face of the divided gear wheel 100a’, 100b’) are positioned between the inner parts 110a’, 110b’ of the divided gear wheels 100a’, 100b’ and the assigned output shaft 20, and outer bearings 500a’, 500b’ between the inner parts 110a’, 110b’ and the outer parts 120a’, 120b’ of the divided gear wheelsl 00a’, 100b’.

The layout of the divided gear wheels 100a, 100b is analogous to the one of divided gear wheels 100a’, 100b’.

It is worth mentioning that the inner ring of inner bearings 400a’, 400b’ is shaped with respect to the shape of engagement component arms 210 (which are shaped according to the formation of guiding means 21 ) and to the engagement means 220 of the engagement component 200, in order the engagement component 200 to be able to pass through the inner bearings 400a’, 400b’, engaging / disengaging the inner parts 110a’, 110b’ of the divided gear wheels 100a’, 100b’.

Figure 24 is a schematic illustration of a horizontal section cut of a gear ratio of a power transmission system 1 , illustrating two consecutive gear ratios.

In this depiction, only two consecutive gear ratios are depicted but it is going without saying that the configuration can comprise more than two gear ratios in an analogous layout.

In addition all the free divided gear wheels of the configuration, are supported by the output shaft 20. The same goes with the dog clutch which can be seen in between the presented gear ratios. In another alternative configuration the free divided gear wheels (and the dog clutches) can alternate to the input shaft 10 and the output shaft 20.

In any case and for the presented exemplary layout, as mentioned before, each gear ratio is defined by a set of a free divided gear wheel and a constantly engaged gear wheel (can be a divided gear wheel as mentioned before).

From this depiction, the positioning of the dog clutch for the presented configuration, is clearer.

The dog clutch is in between the presented divided gear wheels (or gear wheels in general when the engageable gear wheels alternate on the input and output shafts) and is consisted by a dog clutch hub 250 and two engagement components 200 providing the engagement means (teeth) 220 which engage to the inner parts 110.

The dog clutch hub 250 is constantly engaged with the assigned shaft (in this configuration the assigned shaft is the output shaft 20) and the engagement components 200 are able to slide axially, engaging or disengaging to the according inner parts 110.

Both engagement components 200 are torque proof engaged (but can slide axially) to the dog clutch hub 250 and the face of the one engagement component faces the one gear ratio, while the face of the other engagement component faces the other gear ratio.

In addition the engagement components 200, have shifting fork couplings 202 on their outer circumferential surface that house the shifting forks, that adjust the axial (in relation to the axis of the assigned shaft) position of the engagement components 200, with the help of a shifting mechanism(s).

As can be seen from this horizontal section cut, gear ratio“b” is selected, since the engagement component 200b is engaged with the inner part 110b.

By this engagement the inner part 110b of the divided gear wheel 100b is torque proof engaged with the output shaft 20 (i.e. both output shaft 20 and inner part 110b rotate with the same angular velocity). When springs are fully loaded, both inner part 110b and outer part 120b will rotate with the same angular velocity, and torque transfer will be accomplished exclusively via gear ratio“b” (only one engagement component 200 is engaged with the inner part 110 in the entire configuration, i.e. the gear changing action has been completed).

As can be seen, when the engagement component 200b is engaged with the inner part 110b and the gear ratio changing action is completed, every other engagement component 200 will be disengaged.

During gear ratio changing actions, more than one engagement component 200 might be engaged with the corresponding inner parts 110.

In this portrayal, the engagement component 200b, is assigned to engage (and is presented as engaged) with the inner part 110b.

The engagement takes places with the interaction between the engagement means (teeth) 220b, positioned on the front face of the engagement component 200b and the corresponding engagement means 115, positioned on the front face of the inner part 110.

As a person skilled in the art understands, in order to upshift (change gear from gear ratio“b” to gear ratio“a”, since gear ratio“b” is a smaller gear ratio in relation to gear ratio“a”), the engagement component 200b will remain engaged with the inner part 110b as the engagement component 200a is moved axially by the corresponding shifting mechanism(s) [the shifting mechanism(s) is controlled by a Central Processing Unit, that after taking account of certain parameters and fed data, commands the shifting mechanism to perform a gear changing action].

When the engagement means (teeth) 220a of the engagement component 200a, initiate to interact with the engagement means 115a of the inner part 110a of the divided gear wheel 100a, the springs that are longer and have a smaller spring constant will start to compress.

At this moment the engagement component 200b is still engaged with the inner part 110b and most of the power is transferred via gear ratio“b” (a relatively small amount of power is transferred from gear ratio“a”, since it is partially engaged with the shaft and the “softer” springs have started to compress).

The softer spring elements, compress initially by the interaction of both inner part 110a and outer part 120a of the divided gear wheel 100a and the compression of the stiffer spring elements follows.

When the stiffer spring elements compress, the softer spring elements continue to compress as well, due to the positioning of the four spring elements.

As the load being borne by the springs of gear ratio“a” progresses, the load being borne by the springs of gear ratio“b”, decreases, and when the springs of the gear ratio “b” are unloaded, the CPU commands the shifting mechanism(s) to disengage the engagement component 200b.

The“softer” springs provide time, so that the engagement component 200, engages completely with the inner part 110 of the divided gear wheel 100.

In order to downshift (change gear from gear ratio“a” to gear ratio“b”, since gear ratio“b” is a smaller gear ratio in relation to gear ratio“a”), the general outline is generally the same as descripted above.

The engagement component 220a is now engaged with the inner part 110a of the divided gear wheel 100a, and the engagement means 220a interact with the engagement means 115a.

According measurements are taken from according sensors and a gear changing action takes place [again with the help of a Central Processing Unit and corresponding shifting mechanism(s)].

The moment a downshifting action is commanded, a simultaneous command is being given to the engine in order to momentarily interrupt the power, and the disengagement of the engagement component 200a from the inner part 110a initiates, with a simultaneous engagement of the engagement component 200b to the inner part 110b.

When the engagement/disengagement has been completed (position sensors will assists, by defining the position of the engagement components), the engine will continue supplying power depending on the position of the gas pedal (when the engagement/disengagement is completed, the power supply in relation to the accelerator pedal will follow).

The gear ratios “a” and “b” are exemplary gear ratios. The operation is analogous to any consecutive gear ratio in a power transmission system.

In both upshifting and downshifting, as previously mentioned, a Central Processing Unit (CPU) is the one that commands the shifting mechanism(s) to move the desired engagement component 200 in order to engage (or disengage) to the corresponding inner part 110 [via the engagement means (teeth) 220] of the divided gear wheel 100.

The CPU takes account of different measurements (e.g. engine’s revolution, vehicle velocity, selected gear ratio, position of the engagement component etc.) from according measuring instruments before commanding the gear changing action. The driver can manually command a gear changing action (for example by pressing a button).

As can be understood from the above description in both cases (upshifting and downshifting) when the gear changing action is completed, only one inner part 110 is engaged with the assigned shaft (in the presented configuration output shaft 20) via engagement component 200. During the gear changing action, more than one engagement components 200 can at least be partially engaged with their assigned inner parts 110.

Figure 25 is a schematic illustration of the components consisted the dog clutch 230 in an exploded perspective layout. The presented dog clutch 230 is the dog clutch that is used in the previous figure.

More specifically the dog clutch 230 is consisted by three main components.

The first is the dog clutch hub 250 and the other two are engagement components 200, housed to the hub, opposing to each other (i.e. the face of the one engagement component 200a“meets” the one face of the dog clutch hub and the other face of the other engagement component 200b“meets” the other).

The dog clutch hub 250 is constantly engaged with the assigned shaft, for example with splines on the inner circumference as depicted in this view. The engagement components 200 are housed to the dog clutch hub 250, constantly interacting with the dog clutch hub 250 and guided by guiding means 251 which are positioned on the outer circumferential surface of the dog clutch hub 250.

By the constant interaction of the engagement components 200 with the dog clutch hub 250, both parts are torque proof engaged and rotate with the same angular velocity.

Since the dog clutch hub 250 is constantly engaged with the assigned shaft (i.e. rotates with the same angular velocity), both the assigned shaft, the dog clutch hub 250 and the housed engagement components 200 are torque proof engaged and rotate with the same angular velocity.

In addition both engagement components 200 can be moved axially by shifting mechanism(s) resulting in engagement (or disengagement) with the assigned part (inner part of the divided gear wheel).

The shifting fork(s) 205 are engaged in a rotationally free manner with the engagement components 200.

In the presented layout the guiding means - channels 251 are presented as linear grooves/splines (it is obvious that can be either protrusions or cavities).

In another alternative guiding means - channels 251 can be shaped as helixes (i.e. formed in a shape similar to a helical gear) with a corresponding change in the inner engagement means 203.

As a person skilled in the art understands, in that case, engagement components 200, in addition to the axial movement, will also have a rotational one.

As a result when the shifting mechanism(s) pulls (or pushes) the corresponding engagement component 200 in order to engage (or disengage), the engagement component will have an additional angular velocity (increasing or decreasing the angular velocity of the engagement component 200 in relation to the angular velocity of the assigned shaft) depending on how fast (or slow) shifting mechanism(s) actuates the engagement component 200 and the helix characteristics, in order to achieve equal angular velocities between the engaging components (i.e. engagement component 200 and inner part 1 10 of the divided gear wheel 100).

By this feature smoother engagement between the engaging components can be achieved since the engaging components will have same (or similar) angular velocities. The guiding means - channels 251 interact with the inner engagement means 203 of the engagement component 200, allowing axial (or axial and rotational) movement to the engagement component 200 with constant engagement to the dog clutch hub 250.

Additionally the engaging surfaces 221 can be angled assisting the disengagement (or engagement) of the engagement component 200.

It is going again without mentioning that all the changes adapted by the engagement means (teeth) 220 are always made in relation, and with analogous changes, to the engagement means 115 of the inner part 110 of the divided gear 100, resulting in perfect match upon engagement.

In addition every engagement component 200 has a shifting fork coupling 202 that houses the assigned shifting fork 205.

The shifting fork 205 is not rotatably connected to the engagement component 200 (i.e. the engagement component 200 can rotate with the shifting fork 205 not following the rotation).

The shifting fork protrusion 206 is guided in a way that the shifting fork 205 is axially moved, in relation to the axis of the assigned shaft.

Since the shifting fork 205 is attached to the engagement component 200, the two are axially (in relation to the axis of the assigned shaft) moved together.

Figure 26 demonstrates individual parts of the proposed power transmission system of a motor vessel. In this figure a more clear view of the parts consisting the proposed power transmission system used in marine engines can be seen.

As mentioned before the engagement component 200 is torque proof fixed with the prop shaft 10 but has the ability to slide axially depending on the position of the throttle lever, engaging and disengaging the desired gear ratio. The engagement to the shaft takes place with the provision of an engagement surface 203 (inner engagement means) on the inner cylindrical face of the engagement component 200 that is in accordance with the guiding means 11 of the prop shaft 10 which extends for a suitable length in relation to the distance of the first and second divided bevel gears 100a, 100b (transmission elements).

When the first gear ratio is desired, an according movement of the throttle lever, positions the engagement component 200 towards the position of the first divided bevel gear 100a.

As a consequence the engagement means 220a of the engagement component interact with the engagement means 115a positioned on the front surface of the inner part 110a of the divided bevel gear 100a, facing the engagement means 220a, and therefore forcing the engagement component 200 to rotate.

Since the engagement component 200 is torque proof engaged with the prop shaft 10, prop shaft 10 also rotates.

When the inner part 110 is not engaged to the engagement component 200 the softer spring inside the divided bevel gear 100 is considered not to be deformed (the occurring deformation is negligible) and the stiffer spring is also not deformed since is “shorter” in relation to the softer spring and the deflection of the outer part of the divided bevel gear in relation to the inner part is negligible.

When the engagement component 200 begins to engage to the inner part 110 by the interaction of the engagement means 220 of the engagement component 200 with the engagement means 115 of the inner part 110, the rotational force is transferred from the outer part 120 to the softer elastic element and therefore the deformation of the softer spring begins, since it was considered not to be deformed.

Due to the fact that the softer spring has a small spring constant the engagement takes place easily with a small demand in axial force. As it is obvious the softer spring is deformed initially and after the completion of the engagement, the deformation of the stiffer spring follows accompanied by the continuance in deformation of the softer spring.

When the stiffer spring begins to bear load in a progressive manner, the substantial amount of power begins to be transferred. When the load is fully borne by the set of springs, both the inner part 110 and the outer part 120 will rotate with the same angular velocities, and so will the engagement component 200.

It is worth mentioning that the gear changing action is completed during the initial deformation of the softer spring element, before the beginning of the deformation of the stiffer elastic element.

Figure 27 demonstrates an alternative configuration for an inboard power transmission system. In this alternative the engageable gear wheels are provided as divided gear wheels 100a, 100b with their outer parts 120a, 120b comprising a spur gear teething instead of a bevel gear teething.

In addition the divided gear wheels 100 are supported by separate drive shafts 10a, 10b (input shafts) and not by the same.

Therefore, divided gear wheel 100a is supported by drive shaft 10a and divided gear wheel 100b is supported by drive shaft 10b.

In addition drive shaft 10a supports drive gear wheel 300a and drive shaft 10b supports gear wheel 300b which constantly meshes with the drive gear wheel 300a.

Both the drive gear wheel 300a and gear wheel 300b are torque proof fixed with their respective drive shafts 10a, 10b (i.e. rotate as the respective shaft rotates).

As mentioned before divided gear wheels 100a, 100b are free to rotate when their inner parts 110a, 110b are not engaged by an engagement component 200.

In this alternative each divided gear wheel 100a, 100b has a separate engagement component (100a, 100b) and the two do not share a single one as in some previously described configurations. Similarly to the previously described configurations the engagement component (now consisted by engagement components 200a and 200b), is torque proof fixed (i.e. rotating with the same angular velocity) with the assigned drive shaft 10a, 10b but has the ability to move axially in relation to the main axis of the shaft, and the axial position is defined by the respective position of the throttle lever.

In this configuration the power is transferred from drive shaft 10a, 10b to the inner parts 110a, 110b of the divided gear wheels 100a, 100b and via the set of two elastic elements to the outer parts 120a, 120b of the divided gear wheels 100a, 100b.

From there and since the outer parts 120a, 120b are constantly meshed with gear wheel 300c which is torque proof fixed with the prop shaft 20 (output shaft), the power is transferred to the prop shaft.

In the previously described configurations the divided gear wheels 100a, 100b were engaged to the drive gear wheel.

In this alternative configuration both the divided gear wheels 100a, 100b are constantly meshed with the provided gear wheel 300c that is torque proof fixed with prop shaft 20. In prop shaft 20 the propeller is torque proof fixed with to the one end of the shaft.

The operation of the alternative configuration is analogous to the one described in detail above. Therefore upon engaging the desired divided gear wheel 100a, 100b the direction of rotation of gear wheel 300c changes and as a result a forwards or backwards movement can be achieved.

Figure 28 demonstrates a transmission element 100, and more specifically a divided engagement component / divided dog clutch adapted as a transmission element in a gearbox.

The divided engagement component is comparable to the previously described divided gear wheel and therefore can be referenced as a divided gear wheel, with both the divided gear wheel and the divided engagement component being transmission elements. The divided engagement component is consisted by an inner part 110, an outer part 120, elastic elements connecting the inner part 110 and the outer part 120 and engagement means 122 that are adapted to engage a free, engageable gear wheel by interacting with the corresponding engagement means of the free engageable gear wheel.

The inner part 110 and the outer part 120 are angularly deflectable in relation to each other and the deflection is limited by the existence of the elastic elements.

Inner part 110 is provided as torque proof engaged with an assigned shaft by the engagement means 115 provided in the inner circumferential surface of the inner part 110.

The engagement means 115 torque proof fix the inner part 110 directly to the shaft (may be torque proof engaged to the shaft via a dog hub which is torque proof engaged to the shaft). Outer part 120 comprises engagement means 122, adapted to interact with the engagement means of a free, engageable gear wheel.

Upon engagement the otherwise free to rotate gear wheel, is torque proof engaged with the outer part 120.

Since the outer part 120 is connected to the inner part 110 via the elastic elements, the elastic elements will eventually by compressed, up to a point that the rotational forces and or torque from the outer part 120 will be transferred to the inner part 110.

Since the inner part 110 is torque proof engaged with an assigned shaft, by engaging different free, engageable gear wheel different gear ratios can be selected. The selection of different gear ratios is achieved by axially moving the divided engagement component along the assigned shaft.

The presented divided engagement component is axially moved as an entity, and the axial movement takes place by a corresponding shifting fork movement. The shifting fork is coupled to the outer part by the respective shifting fork coupling 202, positioned on the outer circumferential surface of the outer part 120.

The engagement means 122 are provided in both faces of the outer part 120. Therefore engagement means 122a face one free, engageable gear wheel and engagement means 122b face another.

As a result divided engagement component 100 can be received in between two free, engageable gear wheels.

The specific shape/form of the engagement means 122 can vary and the presented one is not restrictive. Therefore the engagement means 122 can be protrusions, cavities or a combination of both, with a respective formation in the engagement means of the free, engageable gear wheels.

The number of the engagement means 122 and the number of the engagement means of the free, engageable gear wheels, do not necessarily have to match. The engagement means provided as cavities may be greater in number than the corresponding engagement means provided as protrusions.

As mentioned above, the inner part 110 is coupled to the outer part 120 by means of at least two elastic elements. In the presented section cut only the softer elastic element 130 (first elastic element) can be seen but a second elastic element is also provided, with the two elastic elements being concentrically positioned, with the one positioned partially arranged within the other, with the proposed positioning not being restrictive. Both inner part 110 and outer part 120 comprise elastic element supports, with the inner elastic element supports 111 being visible in the demonstration.

Inner elastic element supports 111 are provided as two elastic element supports 111 a, 111 b with a“gap” in between them in which the outer elastic element support (not visible in this section cut) can be housed. Finally secure rings 600 are provided, securing the inner part 110 and the outer part 120 in place, with the ability to be angularly deflectable in relation to each other, but axially movable as one.

Figure 29 demonstrates an alternative way of securing the inner part 110 and the outer part 120 of the divided engagement component 100 when the divided engagement component 100 is axially moved as an entity.

In this alternative, the two parts are secured with the help of securing pin 700, which is received in a cavity on the outer circumferential surface. The securing pin 700 may have a spiral first part that is bolted to the outer part 120 and a pin part that secures the inner part 110 in place.

In order to secure the inner part 110 in place, securing groove 710 is provided, and therefore the inner part 110 although is secured (cannot be independently axially moved in relation to the outer part 120) can be angularly deflected in relation to the outer part 120 and vice versa.

As it is obvious there are many ways in which the inner part 110 and the outer part 120 can be secured with the two presented not being restrictive.

Figure 30 and Figure 31 , presents an alternative design where the inner part 110 comprises helical engagement means 115 and is assigned to a dog hub comprising corresponding helical engagement means 21.

In alternative designs, engagement means 115, 21 can comprise a helical groove or protrusion that is adapted to guide the inner part 110 helically i.e. in combined axial and rotational movement.

Figure 32 presents another alternative to the divided engagement component 100 presented previously.

The difference between the previously described configurations is that the elastic elements now comprise a rubber element as a second stiffer elastic element 140.

The first softer elastic element 130 is again a spring element and as a result the elastic elements comprise different types of elastic elements (a spring element and a rubber element). In addition the two elastic elements are not positioned the one within the other but in a position where the first, softer, elastic element 130 is positioned“on top” of the second, stiffer elastic element 140.

In addition the damping elements 118 are provided, with the damping elements 118 being positioned on the inner face of the inner elastic element supports 111 , achieving the same results as the previously mentioned damping elements 128 (positioned on the inner face of the outer elastic element supports 121 ).

Figure 33 presents a yet another alternative to the divided engagement component 100.

In this alternative, the divided engagement component comprises engagement means 122 on one face of the outer part 120 and their position is on an inner circumferential surface instead of a front face.

Due to the fact that the engagement means 122 are provided on one face of the outer part 120 and not on both, every free, engageable gear wheel comprises a single divided engagement component 100 and there are no free, engageable gear wheels sharing a single divided engagement component 100.

Therefore the movement of each divided engagement component 100 can be independent in relation to the movement of the other divided engagement components 100.

In addition in comparison to the alternative presented in the previous figure, the second stiffer elastic element 140 is positioned on top of the first softer spring element 130.

Figure 34 presents an alternative divided engagement component 100.

The presented alternative divided engagement component 100 has an analogous operation and a similar layout to the previously described divided engagement components 100.

The presented alternative is an equivalent to a dog clutch comprising a hub and a dog collar. In this configuration the hub is provided as a dual mass dog hub (divided dog hub) and the dog collar is torque proof engaged to the dual mass dog hub and axially movable towards or away the assigned gear wheels, in order to engage or disengage the desired free, engageable gear wheel.

The presented divided engagement component 100, comprises an inner part 110 and an outer part 120.

The inner part 110 and the outer part 120 are axially fixed to the assigned shaft and the engagement means 123 (dog collar) are axially movable.

The inner part 110 is torque proof engaged with the assigned shaft via the engagement means 115 positioned in the inner circumferential surface.

The inner part 110 and the outer part 120 have a common rotational axis and are arranged concentrically to the assigned shaft.

Further, the inner part 110 is at least partially arranged within the outer part 120 and the inner part 110 is coupled to the outer part 120 by means of two elastic elements 130, 140 (a first and a second elastic element) with different spring constants in relation to each other, arranged in a parallel configuration, so that the inner part 110 is arranged angularly deflectable with respect to the outer part 120 around the common rotational axis (and vice versa).

The previously described elastic elements configurations where the elastic elements where positioned the one within the other or the one on top of the other are also considered to be parallel configuration.

The elastic elements can be spring elements, such a torque springs or a spiral springs, torsional springs, or any other elastic elements such as rubber blocks etc. Further, different types of elastic elements can be combined in a divided engagement component comprising a dual mass dog hub in order to achieve a desired spring characteristic.

The two elastic elements 130, 140 may be positioned within one elastic element compartment, formed by the inner part 110 and the outer part 120.

Alternatively the elastic elements can be positioned in separate compartments but in any case the two elastic elements 130, 140 will be positioned in an arrangement that the first elastic element 130, having a smaller (in relation to the second elastic element 140) spring constant, is initially deformed upon deflection of either the inner or the outer part of the dual mass dog hub (providing the required time in order to achieve a complete engagement before the second elastic element 140 begins to bear load), and the deformation of the second elastic element 140 (having a greater spring constant in relation to the first elastic element 130) follows as the deflection progresses.

In particular, the elastic element compartment can be a closed compartment. Alternatively, the elastic element compartment may be an open compartment that allows heat exchange and a facilitated maintenance of the springs.

The dog collar is axially movable along and on top of the assigned dual mass dog hub, with the dog collar being torque proof engaged with the outer part 120 of the dual mass dog hub, and comprises engagement means 123a on one face of the dog collar and engagement means 123b on the opposite face.

The torque proof engagement of the dog collar with the outer part 120 takes place with the provision of the engagement means 122 on the outer circumferential surface of the outer part 120, that at the same time torque proof engage and guide the dog collar.

The engagement between the dog collar of the divided engagement component 100 and the free, engageable gear wheel is temporally and is achieved with the help of engagement means 123 (e.g. teeth) that are adapted to engage with the engagement means of the free, engageable gear wheel.

Accordingly the dog collar can transfer rotational force and/or torque to the outer part 120 and via the at least two elastic elements 130, 140 to the inner part 110.

Due to the fact that the inner part 110 of the dual mass dog hub is torque proof engaged with the shaft rotational forces and/or torque can be transferred from the free, engageable gear wheel to the shaft and vice versa.

In this demonstration, each of the elastic elements 130, 140 is housed in a different elastic element compartment. As can be seen, the first softer spring element 130 is housed in a compartment defined by the inner elastic element support 111 a and the second stiffer elastic element 140 in a compartment defined by the inner elastic element support 111 b.

In addition secure rings 600 secure in axial place the inner part 110 and the outer part 120, and a shifting fork coupling 202 is provided in order to axially move the dog collar.

Again in this alternative the position of the elastic elements is in a parallel configuration and the first softer spring element 130 is the one that is initially deformed.

It is going without saying that the arrangement for housing the spring elements 130, 140 is not restrictive and both can be housed in a single elastic element compartment with the one spring element being received within the other spring element.

In this presentation the dog collar comprises engagement means in both faces.

It is going without saying that the engagement means could be comprised only in one face but in that case two dog collars should be adopted, one for each free, engageable gear wheel.

As a person skilled in the art understands, the operation is exactly analogous to the previously described configurations of the presented transmission elements, with all the mentioned alternative proposals being able to be adapted to the dual mass dog hub.

In Figures 35 to 39 a schematic illustration of a gear ratio changing sequence is given with the main goal of the illustration being the depiction of the behavior of the elastic elements for a continuously power transfer in a vehicles gearbox.

As can be seen gear ratio n is consisted by the torque proof fixed gear wheel 300a’ which meshes with the free, engageable gear wheel 300a which has the divided engagement component 100a assigned to it. Similarly, gear ratio n+1 is consisted by the torque proof fixed gear wheel 300b’, which meshes with the free, engageable gear wheel 300b which has the divided engagement component 100b assigned to it.

Divided engagement components 100a, 100b comprise engagement means only in one face and therefore are able to be moved independently in relation to each other.

In Figure 35 gear ratio n is selected and 100% of the torque is delivered through gear ratio n.

As can be seen both the elastic elements inside the divided engagement component 100a are completely compressed and the elastic elements inside the divided engagement component 100b are completely decompressed.

In Figure 36 a command is given in order to engage/disengage the free, engageable gear wheels and upon the beginning of the engagement of gear ratio n+1 , the first, softer elastic element begins to compress. Since the first softer elastic elements have a very small spring constant and since the inertia is very small, a smooth easy engagement can be achieved.

In Figure 37 the second, stiffer elastic element of the divided engagement component 100b, begins to compress and as a consequence the second, stiffer elastic element of the divided engagement component 100a begins to decompress. For example 0.1 % of the occurring torque is delivered through gear ratio n+1 and 99.9% is delivered through gear ratio n.

As time passes and as can be seen in Figure 38, more torque is being delivered through gear ration n+1 and less through gear ratio n.

As can be seen as the time passes, the elastic elements of the divided engagement component 100b are more compressed and the elastic elements of the divided engagement component 100a are less compressed.

For example in Figure 18D each gear ratio delivers 50% of the torque.

In Figure 39 100% of the torque is delivered through gear ratio n+1 and as a consequence the elastic elements of the divided engagement component 100b are fully compressed and the elastic elements of the divided engagement component 100a are fully decompressed.

From the above it is made clear that during a gear changing action the torque transfer is progressive and there is not a single moment where there is no torque delivery to the output shaft.

As a person skilled in the art understands, the operation is analogous to the previously described one, when the gearbox comprises any of the previously described divided engagement components 100.

The above described gearboxes comprising divided engagement components 100, allow a quick and smooth engagement when a gear changing action takes place, by comprising at least one of the previously described divided engagement components 100.

As it is obvious all of the described configurations are exemplary and not restrictive and are presented in order to explain and highlight the features of the proposed innovation.

Figure 40 presents a section cut of a gearbox comprising a divided engagement component 100 (for example the divided engagement component 100 presented in figure 28).

In this section cut, a more clear view of divided engagement component 100 can be seen.

More particularly the specific form of the inner part 110, the outer part 120 and the layout of the elastic elements 130, 140, which are provided as spring elements.

Inner part 110 and outer part 120 have a common rotational axis and the inner part 1 10 is at least partially arranged within the outer part 120.

The first softer spring element 130 is partially arranged within the second elastic element 140 and protrudes out of the second elastic element 140 on a front face. As a result, the first softer spring element 130 is longer than the second elastic element 140. The first softer spring element 130 is in constant contact with both the inner part 110 and the outer part 120, and is initially deformed upon deflection of either of the inner or the outer part.

The deformation of the second stiffer spring element 140 takes place after the complete engagement of the assigned free, engageable gear wheel, and as the angular deflection of either the inner part 110 or the outer part 120 progresses.

The stiffer spring element 140 is the one that transfers the significant amount of the occurring load and the softer spring element 130 is the one that assists with the engagement, allowing a smooth, complete engagement prior to the load transfer.

Inner elastic element support 111 and outer elastic element support 121 are provided, supporting the elastic elements 130, 140.

As mentioned before, input gear wheels 300a’ (which mesh with the provided output gear wheels 300a which are provided as engageable gear wheels, free to rotate when being unengaged) are torque proof fixed gear wheels and as a result input shaft 10 provides engagement means 11 , engaging the inner circumferential surface of the input gear wheels and thereby torque proof fix (same angular velocity) said gear wheels to the shaft.

In this demonstration the divided engagement component 100 is positioned directly on top of the shaft. It is going without saying that the divided engagement component 100 could be positioned on top of a hub, with the hub being torque proof engaged with the shaft.

Figure 41 demonstrates a section cut of a gearbox comprising a divided engagement component 100 (for example the divided engagement component 100 presented in figure 28).

The presented gearbox comprises an input shaft 10, supporting input gear wheels (drive wheels) 300a’, 300b’ which are torque proof engaged with the shaft, and an output shaft 20, supporting output gear wheels 300a, 300b (driven wheels). Output gear wheels 300a, 300b are provided as free, engageable gear wheels, not transferring torque when being unengaged.

The engagement takes place via the provided divided engagement component 100“sandwiched” in between the output gear wheels 300a, 300b ( in an alternative configuration, shaft 20 and output gear wheels 300a, 300b could be drive shaft/gear wheels and shaft 10 and gear wheels 300a’, 300b’ could be driven).

The output shaft 20 comprises engagement means adapted to permanently torque proof fix the inner part 110 of the divided engagement component 100.

Although the inner part 110 is provided as torque proof fixed with the shaft 20, it has the ability to be axially moved, engaging and disengaging the desired output gear wheel 300a, 300b.

Input gear wheel 300a’ constantly meshes with output gear wheel 300a, and input gear wheel 300b’ constantly meshes with output gear wheel 300b, therefore defining two gear ratios.

As it is obvious the gearbox may comprise more gear ratios with an analogous layout.

The divided engagement component 100 adopted in this configuration is the one presented in Figure 28.

In this section cut the two elastic elements inside the divided engagement component 100 can be seen.

More specifically the selected exemplary layout comprises two spring elements housed in a single compartment formed by the inner part 110 and the outer part 120, with the two spring elements being positioned the one within the other.

The spring elements, comprise different spring constant in relation to each other.

The first spring element 130 has a smaller spring constant in relation to the spring constant of the second elastic element 140. Therefore the first spring element 130 is softer and the second spring element 140 is stiffen The divided engagement component 100, is presented as not engaged to any of the free, engageable gear wheels 300a, 300b (neutral position).

Finally the engagement means 315 provided on a face of the free, engageable gear wheels can be seen.

Since the engagement means 122 are provided as protrusions, the engagement means 315 are provided as cavities, having a corresponding formation matching the formation of the protrusions.

Figure 42 presents an alternative to the gearbox 1 , where each free, engageable gear wheel has one divided engagement component 100, assigned to it.

Therefore the free engageable gear wheel 300a has the divided engagement component 100a assigned to it and the free engageable gear wheel 300b has the divided engagement component 100b assigned to it.

Both divided engagement components 100a, 100b, operate as described above in detail but in this configuration can be moved independently in relation to each other.

Therefore for example the divided engagement component 100a can maintain its axial position while the divided engagement component 100b being axially moved.

As it is obvious only the one face of the divided engagement component, facing the assigned free, engageable gear wheel, comprises engagement means.

Figure 43 demonstrates a gearbox which may for example be adopted in an electric vehicle comprising two gear ratios and the engagement means 21 , 115 are helically shaped.

As mentioned before this helical formation provides additional angular velocity to the divided engagement component 100 upon axial movement.

As a result when the divided engagement component 100 is axially moved towards the free, engageable gear wheel 300b, due to the selected helix angle, it has an additional rotation in the same direction of rotation as the engageable gear wheel 300b (the direction of rotation is given by the arrows on the top part of the figure).

As a result the absolute angular velocity of the divided engagement component is greater than the absolute angular velocity of the shaft when the gear changing action takes place from a first gear ratio to a second gear ratio.

When the divided engagement component 100 is moved towards the engageable gear wheel 300a, the absolute angular velocity of the divided engagement component is smaller than the absolute angular velocity of the shaft when the gear changing action takes place from a second gear ratio to a first gear ratio.

This feature, assists in smaller differences between the angular velocities of the engaging parts (divided engagement component and gear wheel).

It is worth mentioning that when the gearbox operates in a first gear ratio, the gear selecting mechanism should secure the divided engagement component in place, due to the fact that the divided engagement component wants to be disengaged.

In contrast when the second gear ratio is selected the engagement is granted.

Figure 44 and Figure 45 present sectional views of a gearbox 1 of an outboard or inboard/outboard motor, according to an embodiment of the invention.

As can be seen, the gearbox 1 is consisted by one bevel pinion 300c, a first bevel gear 300a and a second bevel gear 300b.

Both the first and the second bevel gears 300a, 300b are constantly meshed with the bevel pinion 300c, and the main axis of the bevel gears and the bevel pinions, form a 90o angle.

Bevel pinion 300c is torque proof engaged with a drive shaft 10 (input shaft) that receives power from the engine (drive pinion).

Bevel gears 300a, 300b are assigned to the prop shaft 20 (output shaft) which has a marine propeller torque proof engaged with the shaft in one end. Both bevel gears 210, 220 are assigned to the prop shaft 20 but are not constantly torque proof engaged with the prop shaft 20 and therefore are free to rotate when not engaged with the shaft.

The torque proof connection of bevel gears 300a, 300b to the prop shaft 20 is achieved by the outer part 120 of the divided engagement component which is connected with the inner part 110 of the divided engagement component via elastic elements.

Divided engagement component is positioned in between the bevel gears 300a, 300b and is assigned to both bevel gears.

The inner part 110 of the divided engagement component is torque proof engaged with the assigned shaft but has the ability to be moved axially.

The outer part 120 of the divided engagement component has a shifting fork coupling 202 which is coupled to the throttle lever that controls the axial position of the divided engagement component.

By moving the throttle lever in the according position, divided engagement component engages either the first bevel gear 300a or the second bevel gear 300b.

Additionally the divided engagement component may not interact with any of the bevel gears 300a, 300b by staying in a neutral position in between the bevel gears 300a, 300b.

The divided engagement component has engagement means 122a, 122b facing each bevel gear 300a, 300b. As can be seen engagement means 122a are assigned to bevel gear 300a which comprises corresponding engagement means 315a and engagement means 122b are assigned to the bevel gear 300b which comprises corresponding engagement means 315b.

In addition, preferably, both the engagement means 315a, 315b of the first and second bevel gears 300a, 300b and the engagement means 122a, 122b of the divided engagement component, will be consisted by a great number of elements (e.g. teeth).

This is preferred due to the fact that a collision between the engagement means 122a, 122b and the front face of the engagement means 315a, 315b of the bevel gears 300a, 300b is not desired, and therefore a great number of elements (e.g. teeth) is preferred with each element (e.g. teeth) having a pointed face which facilitates the engagement.

When the engagement means 122a, 122b and the engagement means 315a, 315b meet, the significant compression of the softer spring element 130 will begin.

In addition the provision of a great number of engagement means, in both the divided engagement component and in the bevel gears, decreases the demanded tooth depth of the engagement means.

Therefore it is made clear that the decreased occurred inertia (due to the fact that initially upon engagement, only the outer part 120 of the divided engagement component takes part in the engagement/gear selection) accompanied by the existence of the softer spring element 130, result in a quicker and smoother gear change.

Bevel gears 300a, 300b have a bevel gear teething on its outer surface which meshes with the bevel pinion teething of the bevel pinion 300c.

Inner/outer part of the divided engagement component are coupled by two elastic elements.

The set of two elastic elements is consisted by one spring element 130 that has a smaller spring constant and protrudes on a front face of a second elastic element 140 that has a greater spring constant.

In the presented illustration, springs are positioned concentrically in relation to each other with the first spring element protruding out of the second elastic element on a front face, and are housed in an elastic element compartment formed in between the inner part 110 and outer part 120.

As mentioned before each spring consisting the set of springs can be positioned in a separate elastic element compartment or can be positioned the one on top of the other.

The inner part 110 and the outer part 120 have the ability to deflect angularly in relation to each other up till the set of elastic elements is fully loaded. When the set of elastic elements is fully loaded both the inner part 110 and the outer part 120 rotate with the same angular velocity.

Figure 46 exemplary demonstrates individual parts of the proposed gearbox of an outboard motor. In this figure a more clear view of the parts consisting the proposed gearbox used in marine engines can be seen.

As mentioned before the divided engagement component is torque proof engaged with the prop shaft 20 but has the ability to slide axially depending on the position of the throttle lever, engaging and disengaging the desired gear ratio.

The engagement to the shaft takes place with the provision of an engagement surface on the inner cylindrical face of the divided engagement component that is in accordance with the engagement means 21 of the prop shaft 20 which extends for a suitable length in relation to the distance of the first and second bevel gears 300a, 300b.

When the first gear ratio is desired, an according movement of the throttle lever, positions the divided engagement component towards the position of the first bevel gear 300a.

As a consequence the engagement means 122 of the divided engagement component interact with the engagement means 315 positioned on the front surface of the bevel gear 300, facing the engagement means 122, and therefore forcing the divided engagement component to rotate.

Since the divided engagement component is torque proof engaged with the prop shaft 20, prop shaft 20 also rotates.

When the outer part 120 of the divided engagement component is not engaged with the bevel gear 300 the softer spring element 130 of the outer part 120 of the divided engagement component is considered not to be deformed (the occurring deformation is negligible) and the stiffer spring element 140 is also not deformed since is“shorter” in relation to the softer spring element 130 and the deflection of the outer part 120 of the divided engagement component in relation to the inner part 110 of the divided engagement component is negligible. When the outer part 120 of the divided engagement component begins to engage to the bevel gear 300 by the interaction of the engagement means 122 of the outer part 120, with the engagement means 315 of the bevel gear 300, the rotational force is transferred from the outer part 120 to the softer spring element 130 and therefore the deformation of the softer spring element 130 begins, since it was considered not to be deformed.

Due to the fact that the softer spring element 130 has a small spring constant and the outer part 120 has small inertia, the engagement takes place smoothly. As it is obvious the softer spring element 130 is deformed initially and after the completion of the engagement, the deformation of the stiffer elastic element 140 follows accompanied by the continuance in deformation of the softer spring element 130.

When the stiffer elastic element 140 begins to bear load in a progressive manner, the substantial amount of power begins to be transferred.

When the load is fully borne by the set of elastic elements, both the inner part 110 and the outer part 120 will rotate with the same angular velocities.

In Figure 47 a demonstration showing the relative additional angular velocity of the divided engagement component can be seen, when helical engagement means 21 are adapted.

More specifically the black curved arrows show the direction of rotation of the components and the straight arrows show the direction of the axial displacement of the divided engagement component.

Therefore when the divided engagement component is moved towards the bevel gear 300b rotates with an opposite direction of rotation in relation to the direction of rotation of the bevel gear wheel.

At the same time, the softer spring element compresses in the opposite direction, in relation to the direction of rotation of the bevel gear wheel and therefore additional time for the engagement is provided. When the engagement between the bevel gear 300b and the outer part 120 of the divided engagement component initiates, the bevel gear 300“pulls” the divided engagement component, assisting and securing the engagement.

The same goes when the divided engagement component is moved towards the bevel gear 300a.

In figure 48 a detail schematic illustration of the engagement between the inner part 110 of the divided gear wheel 100 and the engagement component 200 can be seen.

In this demonstration, an exemplary engagement means (teeth) 220 formation can be seen.

The engagement means (teeth) 220 of the engagement component 200, are shaped with slightly angled side surfaces resulting in additional axial force that assists with the disengagement of the engaging components.

Due to the formation of the sides of the engagement means (teeth) 220 and the corresponding formation of the engagement means 115 of the inner part 110 of the divided gear wheel 100, an axial force (in relation to the shaft) is applied to the engagement component 200, forcing the engagement component 200, away from the assigned inner part 110, assisting with the disengagement.

As can be seen the engagement means (teeth) 220 are shaped with an 1 o negative angle in both sides of the engagement means (teeth).

Due to the negative angle the base of the engagement means (teeth) 220 are wider in relation to the top of the engagement means (teeth). The 1° angle is selected randomly and it is going without saying that any suitable inclination can be chosen.

In figure 49 an alternative formation of the engagement means (teeth) 220 is presented.

The figure is similar to the previously presented figure.

In this alternative the sides of the engagement means (teeth) 220 are again shaped with a slight angle but the difference in comparison to the previously presented figure lays on the fact that the chosen angle is positive, in comparison to the negative one.

As can be seen the sides of engagement means (teeth) 220 are shaped with an 1° positive angle in both sides of the engagement means (teeth). Again the engagement means 115 of the inner part 110 of the divided gear wheel 100 are shaped accordingly.

The positive angle results in a narrower base in relation to the wider top of engagement means (teeth) 220.

The negative angle chosen for the sides of the engagement means (teeth) 220 (and the according formation of the engagement means 115 of the inner part 110 of the divided gear wheel 100) results in easier disengagement due to the axial force (in relation to the shaft) applied to the engagement component 200.

In case a negative angle is selected, a shifting mechanism that locks the engagement component in place, is preferably applied in order to prevent the disengagement of the components when not desired. In contrast when a positive angle is selected, the prevention of disengagement is granted by the design.

Although figures 48 and 49 present an inner part 110 of a divided gear wheel 100 and an engagement component 200, it is obvious that the engagement means of any of the proposed configurations that engage two transmission elements, can be shaped accordingly.

Furthermore as a person skilled in the art understands, the configurations of power transmission systems comprising one of the presented transmission elements are endless and the illustrated configurations are exemplary, with many combinations of components being possible. LIST OF REFERENCES

I power transmission system / gearbox

10 input shaft

I I engagement means (input shaft)

20 output shaft

21 engagement means / guiding means (output shaft)

Q _Q transmission element / divided gear wheel / divided engagement component

110 inner part (transmission element)

I I I inner elastic element support

115 engagement means (inner part)

116 engagement surfaces (inner part)

118 damping element (inner part)

120 outer part (transmission element)

121 outer elastic element support

122 engagement means (outer part) / gear teething (outer part)

123 engagement means (movable)

128 damping element (outer part)

130 first elastic element (softer)

140 second elastic element (stiffer)

150 set of elastic elements

200 engagement component

201 bushing portion (engagement component)

202 shifting fork coupling / actuator coupling

203 inner engagement means (engagement component)

205 actuator coupling member / shifting fork

206 shifting fork protrusion

210 arms (engagement component)

220 engagement means (engagement component)

221 engagement surfaces (engagement component)

230 dog clutch

250 hub (engagement component)

251 engagement means (hub)

300 gear wheel

305 gear teething

315 engagement means (gear wheel)

400 bearings (inner)

500 bearings (outer)

600 secure rings

700 securing pin

710 securing groove