MOTORCYCLE

The invention relates to a motorcycle. In particular said invention relates to a motorcycle of the monocoque type .

The motorcycle according to the invention comprises:

- a main frame comprising a hollow body for defining an inner space for accommodating an engine and a transmission system;

- a front frame comprising a steer; and

- a rear frame comprising a saddle,

wherein the front frame and/or the rear frame are exchangeably mounted to the main frame by means of mutually cooperating mounting means.

An advantage of the motorcycle according to the

invention is that due to that the front frame and/or the rear frame are exchangeably mounted to the main frame by means of mutually cooperating mounting means it is possible to quickly and/or easily change the drive style of the vehicle by changing the type of front frame and/or rear frame, while the main frame may remain unchanged.

For example, by having a front frame with a steer that is mounted close to the front frame, the driver of the vehicle has to adopt a bent position in order to drive the motorcycle, wherein the belly of the driver is located near the front frame. A motorcycle with such a front frame is a motorcycle of the racing type. The rear frame of such a racing motorcycle is arranged such that the bent position of the driver is supported.

In a different embodiment of the front frame, the steer is mounted at a larger distance from the front frame, thereby allowing the driver to sit more upright and thus more comfortable, such that this embodiment makes the vehicle suitable for driving larger distances. A motorcycle with such a front frame is a motorcycle of the touring type. The rear frame of such a touring motorcycle preferably comprises a double saddle, such that it may support two drivers. Also, the rear frame and/or the saddle may comprise storage space for storing luggage of the driver.

Another advantage of the motorcycle according to the invention is that due to that the front frame and/or the rear frame are exchangeably mounted to the main frame, an easy access to the inner space of the main frame may be provided by removing the front frame and/or the rear frame, thus allowing for easier maintenance of the motorcycle.

Also, the front frame and/or the rear frame may easily be exchanged for another front frame and/or rear frame

comprising a different stiffness, such that the stiffness may easily be tuned

In time, the front frame and/or the rear frame of a motorcycle may become old fashioned or technically outdated. This may be a reason for a driver to buy a new motorcycle, which may result in motorcycles that are no longer used before they are technically finished. An advantage of the vehicle according to the invention is that the front frame and/or the rear frame may be exchanged by a more modern front frame and/or rear frame such that said vehicle is adaptable to the latest fashion or kept technically up to date, thereby increasing the life span of the vehicle.

The main frame according to the invention, comprising a hollow body for defining an inner space, has the advantage that the inner space is relatively large. This allows for different types of engines and/or transmission systems to be accommodated in the inner space. Also, more storage space may be provided. A hydraulic or electronic (i.e. steering by wire) steering device according to the invention, which steering device will be described later, allows for the front frame to be exchangeably mounted to the main frame according to the invention. This is due to that such a hydraulic or electronic steering device allows for easy disconnection of the steer with respect to the steering device located in the front wheel, which cannot be achieved or is at least

difficult to achieve by means of a mechanically connected steer.

The main frame of the vehicle according to the

invention may further comprise the front wheel suspension and/or the rear wheel suspension.

The front frame of the vehicle according to the

invention may further comprise a front headlight and/or a wind screen and/or a fuel tank and/or a mirror and/or tank pads .

The rear frame of the vehicle according to the

invention may further comprise a rear light and/or a storage space.

The allocation of the different functions and elements of the motorcycle to the main frame, the front frame, and the rear frame as described above, allows for the easy exchange of the front frame and the rear frame according to the invention.

The mutually cooperating mounting means are for example chosen from the group comprising a snap connector, a click connector, a mushroom shaped connector, a screw, and a clamp .

Such mutually cooperating mounting means are known perse as so called quick release mounting means and allow for a quick and/or easy exchange of the front frame and/or the rear frame with respect to the main frame. For example, the front frame and the rear frame, respectively the main frame, may comprise outwardly extending flexible snap or click elements that are arranged to be inserted in

respective openings in the main frame, respectively in the front frame and the rear frame, and connected thereto by means of a snap or click action. Alternatively, the main frame, respectively the front frame and the rear frame, may comprise keyholes arranged for receiving mushroom shaped connectors of the front frame and the rear frame,

respectively the main frame, wherein the mushroom shaped connectors are arranged to be inserted in the wide part of the keyhole and then to be displaced such that they extend in the narrow part of the keyhole, such that a coupling between the main frame and the front frame and rear frame is provided. Alternatively, screws may be provided which extend through a hole in the front frame and the rear frame, respectively the main frame, into a threaded hole in the main frame, respectively the front frame and the rear frame. Also, clamps may be provided which provide a connection of the front frame and the rear frame to the main frame by means of a clamping action.

In an embodiment of the motorcycle according to the invention said motorcycle comprises a front wheel and/or a rear wheel, wherein the front wheel and/or the rear wheel is mounted to the main frame by means of a wheel suspension, wherein the main frame extends to a central part of the front wheel and/or the rear wheel, and wherein the wheel suspension is located in the inner space.

Due to that the wheel suspension is located in the inner space it is not exposed to the external environment, such that the wheel suspension is not prone to weather conditions. This results in less wear of the wheel

suspension system. The main frame that extends to a central part of the front wheel and/or the rear wheel functions as a front fork and/or a rear fork, which front fork and/or rear fork thus form one integral part with the main frame.

With a conventional motorcycle, the front fork

comprising the wheel suspension is rotatably mounted with respect to the frame and by rotating the front fork about its longitudinal axis the front wheel is rotated. The longitudinal axis of the front fork is positioned under an angle of about 15° with respect to the vertical in order to enhance steering. Because the front fork comprising the wheel suspension is rotatably mounted, the front fork cannot be integrated in the frame. According to the invention, for steering the front wheel is rotatable with respect to the wheel suspension and the main frame, such that the wheel suspension and the main frame are not rotated during

steering. As a result of that the wheel suspension is not rotated during steering, the wheel suspension may be

vertically mounted instead of under said angle of

approximately 15° from the vertical. A vertically mounted wheel suspension has the advantage that during braking and acceleration the other parameters of the two wheel vehicle are not influenced, as is described with respect to the figures .

Also the rear fork may form one integral part with the main frame, which is a result of the vertically arranged wheel suspension according to the invention.

In another embodiment of the motorcycle according to the invention the main frame is made from a material chosen from the group comprising aluminum, steel, plastic, and a composite material comprising at least one of a thermoset, a thermoplastic and a polyester, optionally reinforced with a fiber, such as a carbon fiber or a glass fiber. A composite material has the advantage that it is strong and relatively light weighted.

Preferably, a front part of the main frame and/or the front frame is compressible under impact, such that it functions as a crumple zone. Such a main frame and/or front frame according to the invention have the advantage that they are able to absorb the energy from the impact during an accident .

In even another embodiment of the motorcycle according to the invention the rear frame comprises a recess in each of two side surfaces of the rear frame with respect to a vertical, longitudinal plane, which recesses are adapted for accommodating a knee of a driver during use.

Such recesses have the advantage that the knees of the driver do not extend beyond the side surfaces of the rear frame, such that they are protected from scraping over the ground if the vehicle falls to one of its sides or during a crash. The rear frame according to the invention provides more space than conventional motorcycles and thus allows for the recesses according to the invention.

Preferably each recess comprises a knee element that is connectable to said recess, which knee element is adaptable in size and form to said knee. Due to said adaptable knee elements the knees may fit completely therein for safety. The knee elements are for example made from a relatively soft, compressible, shock absorbing material and have a suitable thickness, such that the knee elements may function as a buffer during a crash. Such a material may be chosen from the group comprising plastic and rubber.

In even another embodiment of the motorcycle according to the invention the motorcycle comprises a belly element provided over an upper surface of the main frame and/or the rear frame. Such a belly element may be made from a relatively soft, compressible material and has a suitable thickness, such that the belly element may function as a buffer during a crash. Such a material may be chosen from the group comprising plastic and rubber.

In a particular embodiment of the motorcycle according to the invention said saddle may comprise at least one transverse, downwards extending slot in an upper surface of the rear frame, to which slot at least one said belly element is connectable. In a connected position said belly element may extend outward of said slot, such that said belly element functions as a buffer between a belly of the driver and a fuel tank of said motorcycle.

Preferably, the at least one belly element may be adaptable in size and form to the driver, such that the contact between the driver and the vehicle is enhanced and the motorcycle may be controlled easier.

Instead of one belly element a plurality of belly elements may be provided.

In even another embodiment of the motorcycle according to the invention said motorcycle comprises a first opening provided in a front surface of the main frame and/or the front frame with respect to a direction of movement of the motorcycle for reducing the frontal air resistance, wherein the opening is in gas communicating connection with a second opening for discharging air that enters said first opening during use.

Said opening reduces the frontal surface of the

motorcycle and thereby the air resistance of the motorcycle.

Preferably said second opening is arranged in a rear endzone of said motorcycle.

In yet another embodiment of the motorcycle according to the invention a longitudinal tunnel extends between said first opening and said second opening, wherein said tunnel comprises a constriction, and wherein the diameter of said tunnel before and after said constriction is larger than the diameter of the constriction such that said tunnel functions as a Venturi tunnel.

Preferably an exhaust of the engine of the motorcycle discharges into said Venturi tunnel for feeding exhaust gases from the engine to said Venturi tunnel, wherein the exhaust discharges into a part of said Venturi tunnel that is located downstream of said constriction.

As a result of the Venturi effect, the pressure is reduced downstream of said constriction, such that exhaust gases are sucked out of the engine, thereby improving the efficiency of the engine. Also, exhaust gases and hot air from the inner space of the motorcycle are easily removed due the Venturi tunnel. This may enhance cooling of the engine and the inner space of the motorcycle.

In an embodiment of the motorcycle according to the invention a valve is included in said Venturi tunnel, which valve is displaceable between a first position wherein the valve closes the tunnel and a second position wherein the valve opens said tunnel.

By closing and opening said tunnel the performance of the motorcycle may be improved. For example, the valve may be opened during acceleration or constant speed and/or closed during braking.

The valve may preferably be set in any position

including and between said first and second position. For example the valve may be half opened during constant speed, thereby functioning as a spoiler.

Practically said valve is a rotatable butterfly valve that is adjustable in any position including and between said first and second position. In a further embodiment of the motorcycle according to the invention a rear endzone of said Venturi tunnel is shaped as a diffuser and said rear endzone comprises said second opening.

Such a diffuser allows air and exhaust gases to expand.

As a result of the expansion of the air and the exhaust gases the pressure is reduced, such that a downward pressure is exerted on the motorcycle, thereby enhancing the road ability of the motorcycle.

The invention also relates to any vehicle comprising a longitudinal tunnel extending between a first opening provided in a front surface of the vehicle and a second opening, wherein said tunnel comprises a constriction, and wherein the diameter of said tunnel before and after said constriction is larger than the diameter of the constriction such that said tunnel functions as a Venturi tunnel.

The exhaust of the engine of the vehicle may discharge into said Venturi tunnel for feeding exhaust gases from the engine to said Venturi tunnel, wherein the exhaust

discharges into a part of said Venturi tunnel that is located downstream of said constriction. As a result of the Venturi effect, the pressure is reduced downstream of said constriction, such that exhaust gases are sucked out of the engine, thereby improving the efficiency of the engine.

Also, exhaust gases and hot air from any inner space of the vehicle are easily removed due the Venturi tunnel. This may enhance cooling of the engine and the inner space of the vehicle .

In an embodiment of the vehicle according to the invention, a valve may be included in said Venturi tunnel, which valve is displaceable between a first position wherein the valve closes the tunnel and a second position wherein the valve opens said tunnel. By closing and opening said tunnel the performance of the motorcycle may be improved. For example, the valve may be opened during acceleration or constant speed and/or closed during braking.

The valve may preferably be set in any position

including and between said first and second position. For example the valve may be half opened during constant speed, thereby functioning as a spoiler.

Practically said valve is a rotatable butterfly valve that is adjustable in any position including and between said first and second position.

In a further embodiment of the vehicle according to the invention a rear endzone of said Venturi tunnel is shaped as a diffuser and said rear endzone comprises said second opening .

Such a diffuser allows air and exhaust gases to expand.

As a result of the expansion of the air and the exhaust gases the pressure is reduced, such that a downward pressure is exerted on the vehicle, thereby enhancing the road ability of the vehicle.

Said any vehicle comprising the venture tunnel may for example be, but not limited thereto, a car, a truck, a motorcycle. It is noted that the motorcycle may be any motorcycle and is not limited to the motorcycle according to the invention.

In yet another embodiment of the motorcycle according to the invention the main frame or the rear frame comprises a hugger disposed over a part of the periphery of the rear wheel, wherein said part is at least a quarter of the periphery, which quarter extends between the front side of the periphery and the top.

For example said part extends between 230° and 360° in clockwise direction. When said motorcycle comprises said hugger with

optionally an integrated spoiler in combination with said diffuser shaped end zone of the Venturi tunnel, the air and exhaust gases exert said downward pressure on said hugger, thereby effectively exerting said downward pressure on said motorcycle .

In yet even another embodiment of the motorcycle according to the invention, the motorcycle comprises a double clutch transmission system.

In a double clutch transmission system two separate clutches are used for odd and even gear sets. This increases the speed of gear changing, such that the power flow from the engine to the transmission is not interrupted during changing. In accordance with the invention said double clutch transmission system is characterized in that the coupling is located centrally in the motorcycle, i.e. in a central longitudinal plane of the motorcycle, and the gears are located on both transverse sides of the coupling. In particular, the odd gears are mounted on one side and the even gears on the other side. Such a double clutch

transmission system provides the advantages of mass

centralization in the center of the motorcycle and offers a compact transmission system.

In yet even another embodiment of the motorcycle according to the invention, the motorcycle comprises two double cardan shafts for transmitting a rotational force of said engine to a rear wheel of said motorcycle.

A double cardan shaft has the advantage, that vertical reaction forces are eliminated. This enhances the stability of the motorcycle because the rear wheel suspension is not influenced. Two such double cardan shafts have an opposing rotational movement, such that reaction forces due to the motion of the cardan shafts are leveled out. In a further embodiment of the motorcycle according to the invention, the motorcycle comprises a second drive system, wherein said second drive system is located between the engine and said double cardan shafts for transmitting the rotational force of said engine to said double cardan shafts via said second drive system.

An advantage of the combined drive system comprising the second drive system and the double cardan shafts is that the cardan shafts may be smaller in length, thereby

decreasing the unsprung mass of the motorcycle. Preferably, said second drive system is as long as possible and said double cardan shafts as short as possible.

For example, said second drive system may comprise a belt or a chain for driving a shaft that is connected to said cardan shafts. Said shaft preferably extends between said two cardan shafts.

For braking, said motorcycle may comprise a disk brake, said disk brake comprising a disk that is connected to said shaft and a set of mutually cooperating break pads that are adapted to be forced against said disk.

An advantage of said disk brake being located near said shaft, is that the disk brake does not influence the rear wheel suspension and does not form part of the unsprung mass, as is the case with conventional brakes mounted on a wheel disk. Also, as a result of being located in the inner space of the motorcycle, the disk brake is protected from the external environment, thereby decreasing maintenance and improving the lifespan of the brake. A further advantage is that cooling of the disk brake may easily be tuned.

In yet even another embodiment of the motorcycle according to the invention, the tire, the wheel rim and the spokes of the front wheel and/or the rear wheel are

integrally formed as one piece. This has the advantage that the number of parts is reduced. Also, the unsprong mass and the mass moment of inertia are reduced. Further, the stiffness in the radial and axial direction can be tuned independently of each other.

In yet even another embodiment of the motorcycle according to the invention, said motorcycle comprises a second disk brake that is centrally located in a middle vertical longitudinal plane of the front wheel and/or the rear wheel, said second disk brake comprising a second disk that is connected to said wheel and second set of mutually cooperating brake pads that are adapted to be forced against said second disk.

An advantage of such a central disk brake is that the mass moment of inertia is reduced during steering,

accelerating and decelerating as compared to two disk brakes located on opposite sides of a wheel. Also, the weight of one central disk brake is smaller as compared to two disk brakes, which further reduces the mass moment of inertia. Also, due to the mass reduction the unsprung mass is kept as low as possible. Further, in this location the central disk brake is protected from the external environment, thereby decreasing maintenance and improving the lifespan of the brake .

In an embodiment of motorcycle according to the

invention said second disk brake comprises a plurality of sets of mutually cooperating brake pads that are regularly distributed over the periphery of said disk.

An advantage of the plurality of brake pads that are equally distributed over the periphery of the central disk brake, is that the thermal load is equally distributed. For example, three brake pads may be provided that are

distributed each 120°. In yet even another embodiment of the motorcycle according to the invention, said motorcycle comprises a steering system, said steering system comprising a steer and a steering device centrally located in a vertical

longitudinal plane of the front wheel, wherein the steer and the steering device are hydraulically or electronically connected to each other, such that a steering movement of said steer is hydraulically or electronically transmitted to the steering device for rotating said front wheel about a more or less vertical axis.

The advantage of such a steering system is that the wheel suspension may be mounted more or less vertically. Also, such a hydraulic or electronic steering device allows for easy disconnection of the steer with respect to the steering device located in the front wheel, such that the front frame may be exchangeably mounted to the main frame.

It is noted that said more or less vertically axis is preferably offset with respect to the vertical between 5 - 25°, which enhances steering of the motorcycle.

In a practical embodiment of the motorcycle according to the invention said steer comprises a first oil reservoir with a first displaceable valve and said steering device comprises a second oil reservoir with a second displaceable valve, which first and second oil reservoirs are in fluid communicating connection with each other, wherein said steer is connected to said first valve such that a displacement of said steer in a first, respectively second, direction results in a displacement of the first valve in a first, respectively second, direction, wherein the first valve is arranged such that by said displacement of said first valve oil is displaced from the first oil reservoir into the second oil reservoir, wherein the second valve is arranged such that it is displaced in a first, respectively second, direction upon receiving said oil, and wherein said second valve is connected to said front wheel, such that the displacement of the second valve in the first, respectively second, direction results in a rotation in a first,

respectively second, direction of said front wheel about said more or less vertical axis.

In particular said first oil reservoir may comprise two first compartments and said second oil reservoirs comprises two second compartments, wherein each first compartment is in fluid communicating connection with a respective second compartment, wherein oil is displaced from one of the first compartments into one of the second compartments and oil is displaced from the other second compartment into the other first compartment upon displacement of the first valve in the first direction, and wherein oil is displaced from the other first compartment into the other second compartment and oil is displaced from the one second compartment into the one first compartment upon displacement of the first valve in the second direction.

Said second valve may be connected to a rotatable shaft comprising a pinion, which pinion engages the teeth of a curved rack that is connected to a ball head that is connected to said front wheel, such that a rotation of the shaft and the pinion results in said pinion traveling along the length of the rack, thereby rotating the rack and the ball head, and thereby rotating the front wheel about said more or less vertical axis.

Preferably, the longitudinal axis of said ball head extends under an angle of between 5 - 25° with respect to the vertical, and wherein the front wheel rotates about the longitudinal axis of said ball.

As explained above, such an angle of the ball head enhances steering. The angle of the longitudinal axis of the ball head may be adjustable, such that the motorcycle may be adapted to a user's preferences. According to the invention, said angle may be hydraulically adjusted.

In an embodiment of the motorcycle according to the invention said motorcycle comprises fork offset adjusting means for adjusting a fork offset of the motorcycle. Said fork offset adjusting means are for example hydraulic adjusting means.

The invention also relates to a steering system, said steering system comprising a steer and a steering device centrally located in a vertical longitudinal plane of a front wheel of a vehicle, wherein the steer and the steering device are hydraulically or electronically connected to each other, such that a steering movement of said steer is hydraulically or electronically transmitted to the steering device for rotating said front wheel about a more or less vertical axis.

Said steering system according to the invention may be applied to any vehicle, for example, but not limited

thereto, a car, a truck, or a motorcycle. It is noted that the motorcycle may be any motorcycle and is not limited to the motorcycle according to the invention. In case of a motorcycle said more or less vertically axis is preferably offset with respect to the vertical between 5 - 25°, which enhances steering of the motorcycle.

The invention also relates to any vehicle comprising such a steering system. When said vehicle is a car or truck or any vehicle comprising more than one front wheel, said steering system may comprise a plurality of said steering devices, wherein each steering device is centrally located in a vertical longitudinal plane of each front wheel of said vehicle . In a practical embodiment of the steering system according to the invention said steer comprises a first oil reservoir with a first displaceable valve and said steering device comprises a second oil reservoir with a second displaceable valve, which first and second oil reservoirs are in fluid communicating connection with each other, wherein said steer is connected to said first valve such that a displacement of said steer in a first, respectively second, direction results in a displacement of the first valve in a first, respectively second, direction, wherein the first valve is arranged such that by said displacement of said first valve oil is displaced from the first oil reservoir into the second oil reservoir, wherein the second valve is arranged such that it is displaced in a first, respectively second, direction upon receiving said oil, and wherein said second valve is connected to said front wheel, such that the displacement of the second valve in the first, respectively second, direction results in a rotation in a first, respectively second, direction of said front wheel about said more or less vertical axis.

In particular said first oil reservoir may comprise two first compartments and said second oil reservoirs comprises two second compartments, wherein each first compartment is in fluid communicating connection with a respective second compartment, wherein oil is displaced from one of the first compartments into one of the second compartments and oil is displaced from the other second compartment into the other first compartment upon displacement of the first valve in the first direction, and wherein oil is displaced from the other first compartment into the other second compartment and oil is displaced from the one second compartment into the one first compartment upon displacement of the first valve in the second direction. Said second valve may be connected to a rotatable shaft comprising a pinion, which pinion engages the teeth of a curved rack that is connected to said front wheel via any mechanical means, such that a rotation of the shaft and the pinion results in said pinion traveling along the length of the rack, thereby rotating the rack and the mechanical means, and thereby rotating the front wheel about said more or less vertical axis.

In yet even another embodiment of the motorcycle according to the invention, said wheel suspension comprises a hydro pneumatic suspension system that is connected to said front wheel and/or said rear wheel, such that said front wheel and/or said rear wheel is displaceable between a lower position and an upper position.

Preferably, said hydro pneumatic suspension system is vertically mounted with respect to a horizontal plane of said motorcycle.

An advantage of such a vertically mounted suspension system is that the other parameters of the motorcycle are not influenced during accelerating and braking. Also, this allows for the front fork and the rear fork being integrally formed in the main frame.

Said hydro pneumatic suspension system may comprise at least one bellow that is partially filled with a gas. Said gas will provide suspension by compression of said gas.

In a practical arrangement of the motorcycle according to the invention said bellow is in fluid communicating connection with an oil reservoir in which a piston or valve is displaceably mounted, wherein the oil is separated from the gas by means of a flexible membrane, wherein a

displacement of said front wheel and/or said rear wheel from said lower position to said upper position results in a displacement of said piston or said valve, which displacement of said piston or said valve results in the oil in the oil reservoir being displaced into said bellow and thereby compression of said gas in said bellow and thereby in suspension of the front wheel and/or the rear wheel.

The invention also relates to a wheel suspension comprising a hydro pneumatic suspension system that is connected to a front wheel and/or a rear wheel of a vehicle, such that said front wheel and/or said rear wheel is

displaceable between a lower position and an upper position.

Said wheel suspension according to the invention may be applied to any vehicle, for example, but not limited

thereto, a car, a truck, or a motorcycle. It is noted that the motorcycle may be any motorcycle and is not limited to the motorcycle according to the invention.

The invention also relates to any vehicle comprising such a wheel suspension. When said vehicle is a car or truck or any vehicle comprising more than one front wheel, said vehicle may comprise a plurality of said wheel suspensions, wherein each wheel suspension is connected to each front wheel and/or each rear wheel of said vehicle.

Preferably, said hydro pneumatic suspension system is vertically mounted with respect to a horizontal plane of said vehicle.

An advantage of such a vertically mounted suspension system is that the other parameters of the vehicle are not influenced during accelerating and braking. An advantage of such a vertically mounted suspension when said vehicle is a motorcycle, is that said vertically mounted suspension allows for a front fork and a rear fork of said motorcycle being integrally formed in a main frame of the motorcycle.

Said hydro pneumatic suspension system may comprise at least one bellow that is partially filled with a gas. Said gas will provide suspension by compression of said gas. In a practical arrangement of the motorcycle according to the invention said bellow is in fluid communicating connection with an oil reservoir in which a piston or valve is displaceably mounted, wherein the oil is separated from the gas by means of a flexible membrane, wherein a

displacement of said front wheel and/or said rear wheel from said lower position to said upper position results in a displacement of said piston or said valve, which

displacement of said piston or said valve results in the oil in the oil reservoir being displaced into said bellow and thereby compression of said gas in said bellow and thereby in suspension of the front wheel and/or the rear wheel.

For guiding the displacement of said front wheel and/or said rear wheel, said vehicle may comprise guiding means.

In an embodiment of the vehicle according to the invention said guiding means comprise a bracket comprising a plurality of rollers that are displaceable in a rail.

In another embodiment of the vehicle according to the invention the position of the piston or valve in said oil reservoir is adjustable by adjusting the amount of oil in said oil reservoir for adjusting the height of said front wheel and/or said rear wheel.

The invention will now be explained in more detail with reference to figures illustrated in a drawing, wherein:

- figures 1A, IB show an embodiment of a motorcycle according to the invention, wherein 1A is a perspective view, and IB a side view;

figures 2A, 2B show the main frame of the motorcycle of figure 1, wherein 2A is a perspective view, and 2B a side view;

figures 3A, 3B show the front frame of the

motorcycle of figure 1, wherein 3A is a perspective view, and 3B a side view; figures 4A-4C show the rear frame of the motorcycle of figure 1, wherein 4A is a perspective view, 4B a side view, and 4C an underneath view;

figures 5A-5C show three configurations of the motorcycle of figure 1 ;

figures 6A and 6B show a motorcycle according to a second embodiment of the invention, wherein 6A is a

perspective view, and 6B a side view;

figure 7 is a simplified longitudinal cross section of a motorcycle according to a second embodiment of the invention;

figures 8A-8C show the power train of the motorcycle of figure 6, wherein 8A is a perspective view, 8B the cross section of a part of figure 8A, and 8C a top view;

- figures 9A-9C show a first embodiment of the rear wheel suspension of the motorcycle according to the

invention, wherein 9A is a perspective view, 9B is a front view, and 9C is a side view;

figures 10A - 10D show a first embodiment of the front wheel suspension of the motorcycle according to the invention, wherein 10A is a perspective view, 10B is a front view, and IOC and 10D are respective cross sections of the front view of figure 10B;

figure 11 shows the front brake of the motorcycle according to the invention;

figures 12A-12G show the steering system of the motorcycle according to the invention, wherein 12A is a perspective view of the steering system, 12B is a

longitudinal cross sectional side view of a central steering device located in the front wheel, 12C is a cross section of the central steering device, 12D is a second cross section of the central steering device at a second height, 12E is a cross section of the steer and shows the central steering device located thereunder, figure 12F is a longitudinal cross section of the steer, and figure 12G is a longitudinal cross section of means for adjusting the angle of the ball head;

- figures 13A - 13C show a second embodiment of the front wheel suspension of the motorcycle according to the invention, wherein 13A is a perspective view, 13B is a front view, and 13C and 13D are respective cross sections of the front view of figure 12B; and

- figures 14A - 14C show a second embodiment of the rear wheel suspension of the motorcycle according to the invention, wherein 14A is a front view and figures 14B and 14C are respective cross sections of the front view of figure 14A.

Figures 1A, IB show a motorcycle 1 of the monocoque type according to the invention. Figures 6A, 6B show a motorcycle 1 of the monocoque type according to a second embodiment of the invention. Same parts or elements of the motorcycle 1 of figures 1A, IB and the motorcycle 1 of figures 6A, 6B are indicated by the same reference numerals and are described below with respect to figures 1A, IB and figures 6A, 6B .

The multifunctional character of the motorcycle 1 is explained with respect to figures 2-5. The motorcycle 1 comprises a main frame 2 on which a front frame 3 (see figures 3A, 3B) and a rear frame 4 (see figures 4A-4C) are exchangeably mounted by means of mutually cooperating mounting means. As a result of the front frame 3 and the rear frame 4 being exchangeably mounted to the main frame 2, it is possible to quickly and/or easily change the drive style of the motorcycle 1 by changing the type of front frame 3 and/or rear frame 4, while the main frame 2 may remain unchanged. For changing the drive style of the motorcycle 1, the front frame 3 and the rear frame 4 may have many different forms and sizes and may include a plurality of functionalities. Each of the figures 5A-5C shows a possible configuration of the motorcycle 1, which may be configured by means of three different front frames 3 and three different rear frames 4. For example, figure 5A shows a motorcycle 1 that is known as a so called

streetfighter . Such a streetfighter motorcycle has an aggressive appearance and is mainly chosen for its design. The steer 122 is mounted close to the front frame 3, such that the driver has to adopt an uncomfortable position. As such, the motorcycle of figure 5A is most suitable for short driving trips. Figure 5B shows a motorcycle 1 that is known as a so called touring cruiser and that is in particular suitable for touring. The front frame 3 and the rear frame 4 are ergonomically formed, such that a user may travel long distances and the steer is mounted at a predetermined distance from the front frame 3. Figure 5C shows a

motorcycle 1 that is known as a so called supersport

motorcycle, wherein the front frame 3 and the rear frame 4 are aerodynamically formed for high speed and ergonomically formed for comfort. It is clear, that many configurations of the motorcycle 1 may be obtained with different shaped/sized front frames 3 and rear frames 4. Therefore it is clear, that all the possible configurations of figures 3-5 and/or not shown configurations fall within the scope of the appended claims.

According to the invention the basic parameters of the motorcycle 1, such as the wheelbase, sitting height, ball head angle, the fork offset, and inclination angle may be set in correspondence with each configuration and in

correspondence with the user's desires. These parameters may be manually, automatically or dynamically set. Preferably, these parameters are automatically set, for example by a computer code. Preferably, the characteristics of the engine, the gear, steer, spring/damper, brake and traction control may be set in correspondence with each configuration and in correspondence with to the user's desires.

Preferably, these parameters may automatically be set, for example by a computer code.

Figures 1A, IB, 2A, and 2B, show that the main frame 2 comprises a hollow body 10. The hollow body 10 defines an inner space 25 for accommodating an engine and a

transmission system of the motorcycle 1. The hollow body 10 extends to a central part of a front wheel 14 and a rear wheel 15 and functions respectively as a front fork 12 for holding the front wheel 14 and a rear fork 13 for holding the rear wheel 15, which forks 12, 13 are thus an integral part of the main frame 2. With conventional motorcycles the front fork and/or the rear fork cannot be integrated in the frame, in particular not in the main frame of a monocoque type motorcycle. The wheel suspension, the steer and the steering device of the motorcycle 1 according to the

invention do allow for an integrally formed front fork and/or rear fork, as will be explained later. The

manufacturing of an integrally formed main frame 2 is relatively easy and/or cheap as compared to a frame with separate forks. Also, maintenance of the integrally formed main frame 2 is easier. The main frame 2 is formed from a material chosen from the group comprising a composite material comprising at least one of a thermoset, a

thermoplastic and a polyester whether reinforced with a fibre, such as a carbon fiber or a glass fiber, aluminum, steel, plastic. Preferably, the front part of the main frame 2 functions as a crumple zone. Figures 1A, IB, 3A, 3B, 6A, and 6B show that the front frame 3 of the motorcycle 1 comprises front headlights 5 that are located on both sides of the motorcycle \ _r a wind screen 6, and a fuel tank 7.

Figures 1A, IB, 3A and 3B further show that said front frame 3 comprises a belly element 40. The belly element 40 may function as a buffer, such that a belly of the user is not in direct contact with the fuel tank 7 of the engine, which enhances the safety of the driver. Also, the belly element 40 may function as a buffer during a crash.

Preferably, the belly element 40 is ergonomically formed, such that the comfort of the user is improved. Preferably, the belly element 40 is changeable in form and size such that it is adaptable to any user, thereby enhancing the contact between the user and the motorcycle 1, such that the motorcycle 1 can be controlled easier. The belly element 40 is formed as a single element.

Figures 6A, 6B show that instead of one belly element 40, a plurality of such belly elements 40 may be provided, for example two or three. Also, said belly elements 40 of the motorcycle 1 of figures 6A, 6B are included in said rear frame 4 instead of said front frame 3. In particular said belly elements 40 are mounted in downwards extending, transverse slots in an upper surface of the rear frame 4.

Figures 1A, IB, 4A, 4B, 6A, 6B show that the rear frame

4 of the motorcycle 1 comprises a rear light 8 and a saddle 9. Optionally said rear frame 4 comprises a storage space, see figure 5C.

Figures 1A, IB, 4A, 4B, 6A, 6B further show that the rear frame 4 is shaped such that a recess 30 is provided at both the left and the right side of the motorcycle 1 for accommodating the knees or legs of a driver. Said recesses 30 are formed by the front part 27 of the rear frame 4 having an increased width, said front part 27 being

connected to the main frame 2 in connected position. By accommodating the knees of the driver in the recesses 30, the knees are protected from scraping over the ground when the motorcycle 1 falls to one of it sides or during a crash. As a result of the main frame 2 according to the invention and the engines according to the invention, more space is provided for accommodating the knees in respect to

conventional motorcycles, thereby providing more protection than conventional motorcycles. Also, the knees can thus be protected from the weather, such as the wind or rain.

Optionally, the recesses 30 comprise knee elements 31. The knee elements 31 may be ergonomically shaped for more comfort, wherein the knees may fit completely in the knee elements 31 for safety. The knee elements 31 may function as a buffer during a crash. Preferably, the size and form of the knee elements 31 may be changeable, such that the knee elements 31 are adaptable to any user.

Figures 1A, IB and 7 show that an opening 20 of a Venturi tunnel 21, that extends from the front of the motorcycle 1 through the front frame 3, the main frame 2, and the rear frame 4, to the rear of the motorcycle 1, is included in the front part of the motorcycle 1. The opening 20 is formed by an open space 20a above the front wheel 14 which is not covered by the main frame 2 and/or the front frame 3, and an opening 20b in the front frame 3. The opening 20b is covered by a grille. An advantage of the opening 20 is that the frontal surface of the motorcycle 1 is reduced, thereby reducing the air resistance of the motorcycle 1. As is clear from figure 7, due to the Venturi effect of the tunnel 21, the pressure is reduced in an area 24 of an exhaust 71 of engines 70 (see fig. 8A in which the engines 70 are shown) , such that exhaust gases are sucked out of the engine, thereby improving the efficiency of the engine. Also, exhaust gases and hot air from the inner space 25 of the motorcycle 1 are easily removed due the Venturi tunnel 21. This may enhance cooling of the engines 70 and the inner space 25 of the motorcycle 1. As is shown in figures 4A-4C and 7, the rear frame 4 comprises a part 21a of the Venturi tunnel 21, that is connectable to a part 21b of the Venturi tunnel 21 that extends through the main frame 2. An end zone 22 of the part 21a of the Venturi tunnel 21 is formed as a diffuser, in which diffuser air and exhaust gases expand. As a result of the expansion of the air and the exhaust gases the pressure is reduced, such that a downward pressure is exerted on the motorcycle 1, thereby enhancing the road ability of the motorcycle 1. The hot exhaust gases enhance the working of the diffuser. Further, as a result of the pressure reduction the exhaust gases may easily exit the Venturi tunnel 21. As is shown in figures 4A and 7 a butterfly valve 23 is included in the Venturi tunnel 21. Such a butterfly valve 23 may be opened or closed to improve the performance of the motorcycle 1. For example, the butterfly valve 23 may be opened during acceleration or constant speed and/or closed during braking. Preferably, the butterfly valve 23 is rotatable around a horizontal axis 26 extending from left to right in the tunnel 22, when the motorcycle is seen from the front, such that the butterfly valve may be half opened during constant speed, thereby functioning as a spoiler.

Figures 1A, IB, 6A and 6B show that a hugger 50 may be included to the motorcycle 1 that is disposed over a part of the periphery of the rear wheel 15. The hugger 50 preferably extends between the front side of the periphery and the top. The hugger 50 comprises an integrated spoiler 51, thereby improving the road ability of the motorcycle 1. The hugger 50 presses only the rear wheel 15 against the road, such that the spring system is not influenced.

Figures 8A - 8C show the power train of the motorcycle 1, comprising two internal combustion engines 70 of the rotary type, wherein one engine 70 is arranged at the left side with respect to the vertical longitudinal plane of the motorcycle 1 and the other engine 70 at the right side. The engine 70 is described in the international patent

application with number WO-A1-03067031 which is incorporated herein by reference. In other embodiments of the motorcycle according to the invention other types of engines may be applied, such as an electric motor or a conventional

internal combustion engine, such as an Otto engine or a Diesel engine. An advantage of the rotary internal

combustion engines 70 is that such engines are relatively small compared to internal combustion engines that are usually applied in motorcycles, and therefore the rotary engines allow for more freedom in the design of the

motorcycle 1.

Each of the two engines 70 is coupled to a gear 73. In use, the engines 70 rotatably drive the gears 73 into a rotational movement, which rotational movement of the gears 73 is transmitted to gears 74 of a double clutch

transmission system 80. The double clutch transmission system 80 comprises two first hollow shafts 81a, 81b that extend in one line to both sides with respect to the

vertical longitudinal plane of the motorcycle 1. During use, only one of the two first hollow shafts 81a, 81b is

mechanically connected to gear 74 with use of respective connectors 82a, 82b that extend in the respective first hollow shafts 81a, 81b in the longitudinal direction

thereof, such that during use only the connected shaft 81a, 81b is rotated. Both first hollow shafts 81a, 81b comprise fixedly mounted thereto respective gears 83a-85a, 83b-85b, which gears 83a-85a, 83b-85b are connectable to respective gears 86a-88a, 86b-88b of two second hollow shafts 89a, 89b. At all times, except for the short period of time during changing the gears, one of the gears 83a-85a of first hollow shaft 81a is connected to one respective gear 86a-88a of second hollow shaft 89a and one of the gears 83b-85b of first hollow shaft 81b is connected to one respective gear 86b-88b of second hollow shaft 89b. Since only the connected first hollow shaft 81a, 81b is rotated during use, also only the respective second hollow shaft 89a, 89b is rotated. The rotational speed of the second hollow shaft 89a, 89b is dependent on which of the gears 86a-88a, 86b-88b is

connected to respective gears 83a-85a, 83b-85b of the first hollow shafts 81a, 81b, which connection is set by means of respective connectors 92a, 92b that extend in the respective second hollow shafts 89a, 89b in the longitudinal direction thereof. Because both first hollow shafts 81a, 81b remain connected to respective second hollow shafts 89a, 89b, gears may easily be changed by changing which first hollow shaft 81a, 81b is connected to gear 74. This increases the speed of gear changing, such that the power flow from the engines 70 to the transmission is not interrupted during changing. Changing the gear with use of connectors 92a, 92b may be computer controlled, wherein the connector 92a, 92b is set to a lower gear when the motorcycle 1 is decelerating, or set to a higher gear when the motorcycle 1 is accelerating. Setting of a connecter 92a, 92b may be done for the first hollow shaft 89a, 89b that is not driven at that time. For example, when the motorcycle 1 drives in gear four, which gear four may be equal to gear 84a of first hollow shaft 81a, and the motorcycle 1 is slowing down, the connecter 92b will connect to gear three, which gear three may be equal to gear 84b of first hollow shaft 81b, such that when gear changing to gear three is needed this can quickly be done by changing the connection to gear 74 from first hollow shaft 81a to first hollow shaft 81b. In this example, the gears 83a-85a may be the odd gears and the gears 83b-85b may be the even gears. The rotational movement of the rotating second hollow shaft 89a, 89b is next transmitted via

respective belt 90a, 90b, such that shaft 91 is rotated. Said shaft 91 extends between two double cardan shafts 76, each comprising two cardan joints 77, 78, for transmitting the rotational force of shaft 91 via crown gears 104 (see figures 8A, 8B) to the wheel disks 79 for driving the rear wheel 15 (see figures 1A and 6A) . The two double cardan shafts 76 have an opposing rotational movement, such that reaction forces due to the motion of the cardan shafts 76 are leveled out. As a result of the two joints 77,78

vertical reaction forces are eliminated. This enhances the stability of the motorcycle 1 because the rear wheel

suspension is not influenced. An advantage of the power train according to the invention, wherein use is made of both the belt drive and the shaft drive, which belt drive and shaft drive are covered so as to protect them from the external environment, is that maintenance is relatively low. Also, due to this combination of a belt drive and a shaft drive, the shaft drive is smaller as compared to one large shaft drive, thereby decreasing the unsprung mass of the motorcycle 1. A low unsprung mass is preferred because this enhances the roadability of the motorcycle 1. Preferably, the belt drive is extended as far as possible to the rear of the motorcycle 1, which is possible due to the extra space available because of the small size of the rotary engines 70 and the main frame 2 according to the invention, such that the shaft drive is as short as possible. It is noted that instead of a belt drive any applicable drive means could be used, such as a chain drive or a gear drive.

In figure 8C it is further shown, that an electromotor is provided. Said electromotor comprises a rotor 190 that is rotatably mounted and a stator 191 that is fixedly mounted. For example during braking said electromotor functions as a generator for generating electric energy, which electric energy may be stored in a battery. For example during accelerating said stored energy may be used for supplying additional propulsion energy. As such, the motorcycle 1 is a so called (mild) hybrid motorcycle. As a result of the configuration of the transmission system of the motorcycle according to the invention, for example having an improved mass centralization and being compact, the motorcycle according to the invention is particularly suitable for comprising a generator for generating electric energy and thereby for providing a hybrid motorcycle.

Figures 8A-8C show that a disk brake 93 is located near the shaft 91 which disk brake 93 comprises brake pads 95 that are adapted to be forced against disk 94 mounted on shaft 91 during braking, such that during braking the rotational speed of shaft 91 is reduced, thereby slowing down the motorcycle 1. An advantage of the disk brake 93 located near said shaft 91, is that the disk brake 93 does not influence the rear wheel suspension and does not form part of the unsprung mass, as is the case with conventional brakes mounted on a wheel disk. Also, as a result of being located in the inner space 25 of the motorcycle 1 the brake 93 is protected from the external environment, thereby decreasing maintenance and improving the lifespan of the brake 93. A further advantage is that cooling of the brake 93 may easily be tuned. Figures 1A, IB, 9A, 9B and 9C show a first embodiment of the rear wheel suspension 100 by means of which the rear wheel 15 of the motorcycle 1 is mounted to the rear parts of the hollow body 10 that form the rear fork 13. The wheel suspension 100 comprises a, preferably computer controlled, hydro pneumatic spring system 101 including two pistons 102 with piston rods 143 arranged on both the left side and the right side with respect to the vertical longitudinal plane of the motorcycle 1. The two pistons 102 are displaceable in two respective cylinders 107 that are at least partially filled with oil. The cylinders 107 connect to bellows 106, which bellows 106 are at least partially filled with a gas, for example, nitrogen. The gas in the bellows 106 is

separated from the oil in the cylinders 107 by means of a flexible membrane (not shown) . Wheel brackets 103, to which the wheel disks 79 are rotateably mounted via crown gears 104, are mounted to the two piston rods 143, such that the rear wheel 15 is displaceable between a lower position wherein the pistons 102 are fully extended and an upper position wherein the pistons 102 are fully pressed, such that the rear wheel 15 is vertically displaceable with respect to the main frame 2. In an upward movement of the rear wheel 15, for example when the motorcycle 1 rides over a bump in the road, the pistons 102 are moved upwards, thereby pressing the oil in the cylinders 107 in the bellows 106 and thereby compressing the gas in the bellows 106, such that suspension is provided. Preferably said cylinders 107 connect to said bellows 106 via a constriction or two way valve, which constriction or valve provides damping (not shown) . The position of the pistons 102, and therefore the height of the rear wheel 15, may be adjusted by adjusting the amount of oil present in the cylinders 107. For

adjusting the amount of oil present in the cylinders 107 a reservoir filled with oil may be provided (not shown) . The brackets 103 comprise four rollers 150 guided in rails 105, which linearly guide the brackets 103 in the up and down movement. The hydro pneumatic spring system 101 is mounted in a vertical direction relative to the horizontal plane of the motorcycle 1 and to the direction of movement of the motorcycle 1, such that when the wheel 15 moves vertically between the lower and upper position, for example during braking or acceleration, the other parameters of the

motorcycle 1, such as the wheelbase, do not change. This is an advantage of the rear wheel suspension 100 according to the invention. The spring-damper characteristics may

dynamically be controlled by a computer.

Figures 10A - 10D, and 11 show a first embodiment of the front wheel suspension 110 by means of which the front wheel 14 of the motorcycle 1 may be mounted to the front parts of the side panels 10 that form the front fork 12. The front wheel suspension 110 comprises a, preferably computer controlled, hydro pneumatic spring system 111 including two pistons 112 with piston rods 144 arranged on both the left side and the right side with respect to the vertical

longitudinal plane of the motorcycle 1. The two pistons 112 are displaceable in two respective cylinders 109 that are at least partially filled with oil. The cylinders 109 connect to bellows 108, which are at least partially filled with a gas, for example nitrogen. The gas in the bellows 108 is separated from the oil in the cylinders 109 by means of a flexible membrane (not shown) . To both of said piston rods 144 is a shaft 113 mounted, to which shaft 113 the front wheel 14 is rotateably connected by means of a central wheel disk 114, such that the front wheel 14 is displaceable between a lower position wherein the piston 112 is fully extended and an upper position wherein the piston 112 is fully pressed, such that the front wheel 14 is vertically displaceable with respect to the main frame 2. In an upward movement of the front wheel 14, for example when the

motorcycle 1 rides over a bump in the road, the pistons 112 are moved upwards, thereby pressing the oil in the cylinders 109 in the bellows 108 and thereby compressing the gas in the bellows 108, such that suspension is provided.

Preferably said cylinders 109 connect to said bellows 108 via a constriction or two way valve, which constriction or valve provides damping (not shown) . The position of the pistons 112, and therefore the height of the front wheel 14, may be adjusted by adjusting the amount of oil present in the cylinders 109. For adjusting the amount of oil present in the cylinders 109, a reservoir filled with oil may be provided (not shown) . The hydro pneumatic spring system 111 is mounted in a vertical direction relative to the

horizontal plane of the motorcycle 1 and to the direction of movement of the motorcycle 1, such that when the wheel 14 moves vertically between the lower and upper position, for example during braking or acceleration, the other parameters of the motorcycle 1, such as the wheelbase, do not change. This is an advantage of the front wheel suspension 110 according to the invention. The shaft 113 is mounted to the piston rods 144 by means of brackets 118, which brackets 118 are linearly guided in the up and down movement by means of four rollers 119 which are guided in rails 120, such that when the shaft 113 moves vertically between the lower and upper position, the shaft extends perpendicular relative to the two piston rods 144. The spring-damper characteristics may dynamically be controlled by a computer. Figures IOC and 10D further show that the shaft 113 is displaceable in the longitudinal direction of the motorcycle 1 over the at least a part of the length of rods 117 that extent in the longitudinal direction of the motorcycle 1 by adjusting the amount of oil present on either side 140 of a displacer 141 to which the shaft 113 is mounted, such that the wheel base can be set according to a user's preferences. The wheel base can be set manually, automatically of dynamically.

The front wheel suspension and the rear wheel

suspension according to the invention, wherein the hydro pneumatic spring systems extend in a substantially vertical direction relative to the horizontal plane of the motorcycle 1 and to the direction of movement of the motorcycle 1, such that during braking and acceleration the other parameters of the motorcycle 1 are not influenced, allow for the

integration of both the front fork and the rear fork in the main frame. Thus the vertical wheel suspension system according to the invention allows for the hollow body 10 of the main frame 2 of the motorcycle 1 to extend to a central part of the front wheel 14 and the rear wheel 15 and to have the wheel suspension system mounted to the inner side of the hollow body 10, i.e. to have the wheel suspension system located in the inner space 25.

Figure 11 shows a central disk brake 115 that is located in the center of the front wheel 14. The middle longitudinal plane of the disk brake 115 is equal to the middle longitudinal plane of the front wheel 14. The disk brake 115 comprises three brake pads 116 that are

distributed each 120° over the periphery of the wheel disk 114 to which the front wheel 14 is mounted by means of mounting means 142, wherein the brake pads 116 are adapted to be forced against wheel disk 114 during braking, such that during braking the rotational speed of the wheel 14 is reduced, thereby slowing down the motorcycle 1. An advantage of the central disk brake 115 which middle longitudinal plane is equal to the middle longitudinal plane of the front wheel 14 is that the mass moment of inertia is reduced during steering, accelerating and decelerating as compared to the conventional two disk brakes located on opposite sides of a wheel. The reduction in mass moment of inertia is a result of both the location of the disk brake, i.e. in the middle longitudinal plane of the wheel 14 instead of on the opposite sides of the wheel, as the reduction in mass. Also, due to the mass reduction the unsprung mass is kept as low as possible. Further, in this location the central disk brake 115 is protected from the external environment, thereby decreasing maintenance and improving the lifespan of the brake 115. A further advantage is that cooling of the brake 115 can easily be tuned. An advantage of the plurality of brake pads 116 that are equally distributed over the periphery of the central disk brake, in this example three but more or less brake pads may be provided, is that the thermal load is equally distributed.

Figure 11 further shows the front wheel 14. The tire, the wheel rim and the spokes of the front wheel 14 are integrally formed as one piece according to the invention. This has the advantage that the number of parts is reduced. Also, the unsprong mass and the mass moment of inertia are reduced. Further, the stiffness in the radial and axial direction can be tuned independently of each other.

Figures 12A-12G show the steering system of the

motorcycle 1, comprising a central steering device 121 that is connected to said shaft 113. The central steering device 121 comprises a ball head 123, which forms the rotation axis around which the front wheel 14 rotates with respect to the frame of the motorcycle 1 and the wheel suspension 110 for steering the motorcycle 1. The longitudinal direction of the ball head 123 extends under an angle of approximately 15° with respect to the vertical in order to enhance steering. Said angle of the ball head 123 is hydraulically adjustable, as will be described with respect to figure 12G. The

distance between the ball head 123 and the center of the front wheel 14, also called the fork offset, is

hydraulically adjustable by fork offset adjusting means 124, see figure 12B. By feeding oil to one side of said means 124 and discharging oil from the other side of said means 124 the ball head 123 is moved in translation to the other side of said means 124 and visa versa, thereby changing the distance of the ball head 123 with respect to the center of the front wheel 14. The central steering device 121 is hydraulically connected to steer 122 and not mechanically. One advantage of this mechanical uncoupling is that this allows the hydro pneumatic spring system 111 to be mounted in the vertical direction relative to the horizontal plane of the motorcycle 1 and to the direction of movement of the motorcycle 1 as is explained above. With conventional motorcycles steering is provided by rotating the front fork that is mechanically connected to the steer. The front fork which comprises the suspension system therefore needs to be mounted approximately 15° from vertical, in order to enhance steering. In accordance with the invention the steering device and the steer are not mechanically coupled, such that the longitudinal direction of the ball head 123 deviates approximately 15° from vertical as is described above, but the wheel suspension may be vertically mounted, thus

providing the advantages of not influencing the other parameters of the motorcycle during accelerating and braking and to have the front fork and rear fork integrally formed in the main frame. Also, the steer 122 may be mounted anywhere, thereby increasing the freedom of design.

Furthermore, this allows for the easy exchange of the front frame 3 for a different frame 3. In figure 12E a horizontal cross section of the steer 122 and the steering device 121 located thereunder is shown. This cross section shows that the steer 122 comprises a first disk shaped oil reservoir

125 comprising two first compartments 126, to which first reservoir 125 first outer endzones of connecting tubes 127 are connected, wherein the other outer endzones of tubes 127 are connected to two second compartments 129 of a second disk shaped oil reservoir 130 of the central steering device 121, see figure 12D. The two first compartments 126 are separated from each other by means of a first valve 131. The two second compartments 129 are separated from each other by means of a second valve 132. The first valve 131 is mounted to a shaft 133 of the steer 122, such that by rotating the steer 122 the first valve 131 is rotated accordingly. The volumes of the first compartments 126 are defined by the first valve 131 and a fixed partition 134, such that by rotating the valve 131 in the direction of the fixed first partition 134, the volume of one of the first compartments

126 is reduced and the volume of the other of the first compartments 126 is enlarged. By this volume change, oil is pressed out of the one of the first compartments 126 into respective tube 127, such that the oil enters one of the second compartments 129. Due to the addition of oil to the one of the second compartments 129, the second valve 132 rotates in the direction of a fixed second partition 135, such that oil is pressed out of the other of the second compartments 129, into respective tube 127 and into the other of the first compartments 126. The second valve 132 is mounted to a shaft 136 of the central steering device 121, such that due to the rotating second valve 132, the shaft

136 rotates accordingly. As is seen in figure 12C, a pinion

137 is fixedly mounted to shaft 136, such that the pinion 137 is rotated with shaft 136. The pinion 137 engages the teeth of a curved rack 138, such that during rotation of shaft 136 and the pinion 137, said pinion 137 travels along the length of the rack 138, thereby rotating the rack 138 which is fixedly connected to ball head 123, and thereby rotating the wheel 14 during steering. This way, the wheel 14 rotates with respect to the front wheel suspension 110, the front fork 12 and therefore the frame 10. The steering device according to the invention also allows for so called steer by wire.

Figure 12G shows the means for hydraulically adjusting the ball head angle with respect to the vertical. Said means comprise a disk shaped oil reservoir 180 comprising two compartments 181. The two compartments 181 are separated from each other by means of a rotatable valve 182 and a fixed partition 183. Said rotatable valve 182 is connected to said shaft 113, which shaft 113 is connected to the ball head 123. The two compartments 181 comprise connectors 184 for feeding or discharging oil to said two compartments 181. By feeding oil to one of said two compartments 181 and by discharging oil from the other compartment 181, said valve 182 is rotated in the direction of the other compartment 181, thereby rotating the shaft 113 in the direction of the other compartment 181. By rotating said shaft 113 the angle of the ball head 123 with respect to the vertical is

changed. Thus, by feeding and discharging oil to said compartments said shaft 113 and thereby the ball head 123 is rotatable and the ball head angle adjustable. The ball head angle is indicated in figure 12B by reference numeral 185.

Said feeding or discharging oil to said means for hydraulically adjusting the ball head angle and/or the means for adjusting the fork offset is preferably electronically controlled . Figures 13A - 13D show a second embodiment of the front wheel suspension 160 by means of which the front wheel 14 of the motorcycle 1 may be mounted to the front parts of the hollow body 10 that form the front fork 12. Figure 2A shows recesses 151 provided in the inner side of the front parts of the hollow body 10, which recesses 151 are arranged for accommodating the front wheel suspension 160 according to the second embodiment. The front wheel suspension 160 comprises two disk shaped oil reservoirs 161, which are located on both the left side and the right side of the wheel 14 with respect to the longitudinal vertical direction of the motorcycle 1. Each reservoir 161 comprises a fixed partition 167 and a rotatable valve 166, which rotatable valve 166 is rotatably mounted in said reservoir 161 by means of a rotatable central axis 168. Said rotatable central axis 168 is connected to a gear 164, that is

rotatably mounted with respect to a gear-rack 165. An up and down movement of the front wheel 14 and thereby of the gear 164, provides for a rotational movement of the gear 164, thereby rotating the axis 168 and the valve 166. The

partition 167 and the valve 166 divide the inner space of the reservoir 161 into two compartments 162, wherein the volume of each of the two compartments 162 is changeable by means of a rotational movement of the valve 166. Only one compartment 162a of the two compartments 162 is filled with oil and comprises a connector 163 to which a first outer endzone of a connecting tube is connected (not shown) . The other outer endzone of the connecting tube is connected to a connector of a bellow (not shown, but similar to the bellow 108 of the suspension system of figures 10A-10D) , which bellow is at least partially filled with a gas, for example nitrogen. As for the first embodiment of the front wheel suspension, the up and down movement of the front wheel 14 is guided by means of brackets 118, which brackets 118 are linearly guided by means of four rollers 119 which are guided in rails 120. During a vertical movement of the front wheel 14 in an upward direction, the central axis 168 of the reservoir 161 is rotated in a first direction and thereby the valve 166 is rotated in the first direction, which first direction is in the direction of the connector 163. Due to the rotation of the valve 166 in the first direction the volume said one compartment 162a is reduced, such that the oil is pressed out of that one compartment 162a into the bellow, thereby compressing the gas present in the bellow and providing suspension for the front wheel 14. The valve 166 thereby functions as the piston 112 of the suspension system of figures 10A-10D. The front wheel 14 is

displaceable between a lower position wherein the valve 166 is located adjacent to one side of the partition 167, which one side is facing away from said connector 163, and an upper position wherein the valve 166 is located adjacent to the other side of the partition 167, which other side is facing the connector, such that the front wheel 14 is vertically displaceable with respect to the main frame 2. The position of the valve 166, and therefore the height of the front wheel 14, may be adjusted by adjusting the amount of oil present in the compartment 162a.

Figures 14A to 14C show a second embodiment of the rear wheel suspension 170 by means of which the rear wheel 15 of the motorcycle 1 may be mounted to the rear parts of the hollow body 10 that form the rear fork 13. The rear wheel suspension 170 comprises a disk shaped oil reservoir 111, which is located in the center of the rear wheel 15. The central reservoir 171 comprises a fixed partition 177 and a rotatable valve 176, which rotatable valve 176 is rotatably mounted in said disk 171 by means of a rotatable central axis 178. Said rotatable central axis 178 is connected to gears 174, located on both the left side and the right side of the wheel 15 with respect to the longitudinal vertical direction of the motorcycle 1, that are rotatably mounted with respect to gear-racks 175. An up and down movement of the rear wheel 15 and thereby of the gears 174, provides for a rotational movement of the gears 174, thereby rotating the axis 178 and the valve 176. The partition 177 and the valve 176 divide the inner space of the disk 171 in two

compartments 172, wherein the volume of each of the two compartments 172 is changeably by means of a rotational movement of the valve 176. Only one compartment 172a of the two compartments 172 is filled with oil and comprises a connector 173 to which a first outer endzone of a connecting tube is connected (not shown) . The other outer endzone of the connecting tube is connected to a connector of a bellow (not shown, but similar to bellow 106 of the suspension system of figures 9A-9C) , which bellow is at least partially filled with a gas, for example nitrogen. As for the first embodiment of the rear wheel suspension, the up and down movement of the rear wheel 15 is guided by means of brackets 103, which brackets 103 are linearly guided by means of four rollers 150 which are guided in rails 105. During a vertical movement of the rear wheel 15 in an upward direction, the central axis 178 of the disk 171 is rotated in a first direction and thereby the valve 176 is rotated in the first direction, which first direction is in the direction of the connector 173. Due to the rotation of the valve 176 in the first direction the volume said one compartments 172a is reduced, such that the oil is pressed out of that one compartment 172 into the bellow, thereby compressing the gas present in the bellow and providing suspension for the rear wheel 15. The valve 176 thereby functions as the piston 102 of the suspension system of figures 9A-9C. The rear wheel 15 is displaceable between a lower position wherein the valve 176 is located adjacent to one side of the partition 177, which one side is facing away from said connector 173, and an upper position wherein the valve 176 is located adjacent to the other side of the partition 177, which other side is facing said connector 173, such that the rear wheel 15 is vertically displaceable with respect to the main frame 2. The position of the valve 176, and therefore the height of the rear wheel 15, may be adjusted by adjusting the amount of oil present in the compartment 172a.

The invention is not restricted to the variants shown in the drawing, but it also extends to other preferred embodiments that fall within the scope of the appended claims .

Although the invention is described with respect to a motorcycle it is clear for the skilled person that the invention is related to any two wheeled vehicle, such as, but not limited thereto, a scooter, or to a three wheeled motor cycle. Also, at least many of the described features of the invention may be applied to any type of vehicle, such as, but not limited thereto, a car or a truck.