The invention is directed to a drive system for a human-powered machine generating a rotating movement comprising a first and second actuator mounted for a reciprocating motion.

Such drive systems are known and for example described in US-A-6000707. This drive system generates a rotating movement to power a rear drive wheel of a two wheeled vehicle. The drive system comprises of a first and second pedal mounted for linear reciprocating motion. The pedals are mounted on a power transmitter cable, which cable forms a closed loop running from a pulley at the front of the vehicle via one of the pedals to a freewheel mounted on the axle of the drive wheel and via a pulley back to another freewheel mounted on the axle of the drive wheel and back to the pulley at the front via the other pedal.

GB-A-2279918 describes a treadle-cycle having a first and second tread pedal mounted in slotted tubes for linear reciprocating motion. Each pedal is connected to a cam by means of a cable. The cams have a common shaft with an intermediate drive wheel. The cams are provided with one way clutches or freewheels such that the alternative rotational directions of the cams are transferred to a single rotational direction of the common shaft and thus the intermediate drive wheel.

FR2728532 and US6155584 describe the same bicycle having pedals which move simultaneously back and forth along a rails. Thus the pedals are not mounted for a reciprocating motion with respect to each other. The pedal actuators are connected by a cable to a pulley of an ovoidal shape which can rotate along a horizontal axis and is connected to a freewheel. The pulleys are provided with a spring to bring the pulley to a starting position after each cycle.

A disadvantage of these known drive systems is that the efficiency is not significantly high enough to compete with the standard bicycle drive system having rotating pedals.

The object of the present invention is to provide a drive system for a human- powered machine generating a rotating movement comprising a first and second actuator mounted for a reciprocating motion which has a high efficiency. This is achieved with the following drive system.

A drive system for a human-powered machine generating a rotating movement to one or more drive axles comprising a first actuator and a second actuator mounted for a reciprocating motion,

a first power transmitter cable running from the first actuator to an intermediate drive system and a second power transmitter cable running from the second actuator to the intermediate drive system, wherein the intermediate drive system comprises a first rotatable means over which the first power transmitter cable runs and a second rotatable means over which the second power transmitter cable runs such that first rotatable means and second rotatable means rotate in alternating directions along a common intermediate axle or along two different intermediate axles as a result of the reciprocating motion of the first and second actuator and wherein the intermediate drive system further comprises an intermediate power transmitter cable or cables running from the intermediate axle or axles to a first and second freewheel, each freewheel co-axial connected to the same or different drive axle such that the resulting movement in alternating directions of power cable or cables by rotation of the intermediate axle or axles is transferred in a predetermined rotational direction of the drive axle or drive axles.

Applicants found that the drive system can generate a rotational movement to a drive axle with a higher efficiency than the known systems. Further advantages will be discussed below when describing the preferred embodiments of the invention.

Reference to horizontal, vertical, upper, lower, front, rear backwards and forward in this description refer to the normal use of the drive system and vehicle according to this invention as also shown in the Figures. These terms are not limiting with respect to the orientation in which the drive system and vehicle according to this invention may be used.

First rotatable means and second rotatable means rotate in alternating directions along a common intermediate axle or along two different intermediate axles. To achieve this the first rotatable means and second rotatable means are non- rotatably connected to this common intermediate axle or to the two different intermediate axles. The first and second rotatable means may be combined as one rotatable means or be separate means. Suitably these means direct the first power transmitter cable and second power transmitter cable with a fixed or variable distance to the intermediate axle when the means are rotated upon actuation of the actuators. In this manner the reciprocating movement of the actuators is transferred to a rotational movement of the intermediate axle or axles.

The first and second rotatable means are suitably disks having a certain thickness such that the power transmitter cable can run along its periphery. The disk may have the design of a circle wherein an intermediate axle is positioned in the centre. This will result in that the distance and thus the leverage between cable and intermediate axle is constant upon actuation of the pedals. Suitably the distance as determined by the design of the first and/or second disk between their respective first or second cable and the intermediate axle of the intermediate drive system varies with the position of the respective first or second actuator such that the smallest distance as determined by the design of the disk is when the actuator is in an intermediate position and the greatest distance as determined by the design of the disk is when the actuator is at or near one or both of its extreme positions. This results in that the leverage of the drive systems varies with the position of the actuators resulting in a drive system which operates more fluently and allows for a movement of the users legs and/or arms that is more natural and close as possible to, for example, normal walking or running. Such variation in distance and leverage may be achieved by using circular disks having an eccentric design with respect to where the intermediate axle is positioned. Preferably disks are used having an irregular form, also referred to as a cam. It is found that cams having a certain design are most suitably applied to achieve the above variation in leverage.

The disk can be made of light weight metals, like for example aluminium, or polymers, like engineering plastics based on polyamides. The disk may be provided with openings to reduce weight. The polymers may optionally be fibre reinforced polymers. Suitably one end of the first cable is fixed to the first disk and one end of the second cable is fixed to the second disk. First and second disk are suitably positioned adjacent with respect to the other disk when they have a common axle. The first and second cable may also be connected wherein the cable is fixed to said first and second disk. This common cable may make a full rotation around the common axle to create sufficient friction to let the common cam interlock with the cable. Interlocking with the cable can also be achieved by mechanical interlocking, such as when the cable is a chain or belt having for example V-shaped gear teeth.

The cable may thus be any flexible elongated power transmitter, such as a cable, chain or belt and is not limited to the literal meaning of the word cable. A preferred cable is made of stretched steel or synthetic material which does not allow much creep. Examples of such materials are fibres made from Ultra-High Molecular Weight Polyethylene, such as the Dyneema® Fiber.

The first rotatable means and second rotatable means may rotate around different intermediate axles. In such an embodiment each of the two different intermediate axles will rotate alternatingly in different directions. This rotation and the moment when the direction changes due to the reciprocating motion of the actuators does not necessarily have to be the same. Preferably this moment is the same. Both intermediate axles will be provided with an intermediate drive wheel. Along each intermediate drive wheel a separate intermediate power transmitter cable runs to a separate freewheel. Each freewheel is co-axial connected to the same single drive axle or to separate drive axles. This embodiment thus enables one to power at least two drive axles separately, enabling for example a vehicle with at least two wheels which are powered separately by the drive system according to the invention. For example a two wheeled vehicle may suitable comprise one drive axle connected to the front wheel and the other drive axle connected to the rear wheel.

Preferably first and second rotatable means have a common intermediate axle. This simplifies the design and results in a higher efficiency than when two separate intermediate axles are used. Preferably the first and second freewheel are co-axial connected to the same drive axle to even further increase efficiency. In such an embodiment it is preferred that the intermediate power transmitter cable runs from a third intermediate drive wheel, first freewheel, a pulley, second freewheel and back to the third intermediate drive wheel. In this configuration the third intermediate drive wheel and the intermediate power transmitter cable will alternatingly move in one and the opposite direction. For one direction of the intermediate power transmitter cable one of the freewheels will engage with the drive axle to generate rotational movement to said drive axle in a predetermined direction and for the opposite direction of the intermediate power transmitter cable the other freewheel will engage with the drive axle to generate rotational movement to said drive axle in the same predetermined direction.

The use of a third intermediate drive wheel is advantageous because it enables gearing between the rotational movement of the intermediate axle of the intermediate drive system and the rotational movement of the drive axle by altering the radius of the third intermediate drive wheel. Alteration may be achieved by simply substituting the third intermediate drive wheel with an intermediate drive wheel having a different radius or by using different intermediate drive wheels having a different radius and wherein the intermediate power transmitter cable can be moved from one wheel to another. More preferably a single third intermediate drive wheel is used of which its radius can be, suitably seamlessly, altered by the user of the drive system.

The first actuator and second actuator may be any means operable by a human user which result in a rotating of the first and second means via the first and second power transmitter cable by a reciprocating motion. Examples are pedals operable by the legs of a user and/or are handles operable by the arms of the user. Pedals and handles may be used in combination wherein the drive system may comprise of two sets of first and second power transmitter cables. These cables may rotate different rotatable means or work in conjuncture wherein a handle and pedal rotate one rotatable means and the other set of handle and pedal operates a second rotatable means. It may even be conceived that the first actuator is a pedal and the second actuator is a handle for use, for example, by users who are disabled to use both legs. Preferably the actuators are pedals and more preferably the drive system comprises one set of first and second pedals and their corresponding first and second power transmitter cable and first and second rotatable means.

The actuators are mounted for a reciprocating motion. This means that the first actuator is mounted for a reciprocating motion relative to the second actuator. Such a motion will in turn generate the required rotation of the rotatable means. The movements of the actuators will be in parallel pathways. The pathways may be along a straight line and/or slightly arcuate line. Preferably the first actuator and second actuator are first and second pedals mounted for a reciprocating motion. A slightly arcuate pathway may result in a movement of the leg of the user which is more close to natural walking or running.

The actuators can move to their starting position in the opposite direction by using for example springs or by actuation by the user. Preferably the drive system will be provided with a linkage between said actuators such that upon motion of one actuator in one direction the other actuator moves in the opposite direction, and vice versa. This may be achieved in many different manners, as for example described in the prior art. The following description provides a preferred embodiment when the actuators are pedals. Similar solutions may be conceived when the actuators are handles.

Preferably the first cable is fixed at one end to a first fixed point, the first pedal is provided with a pulley over which the first cable runs from the fixed point to the first cam. The second cable is fixed at one end to a second fixed point, the second pedal is provided with a pulley over which the second cable runs from the fixed point to the second cam and wherein the linkage between first and second pedals is provided by a connecting cable running via one or more connecting pulleys. This results in that by one stroke of a pedal twice the cable distance is actuated. This results in a double intermediate phase in which the user can exercise the highest force. This however also results in double start and end phases in which the user can exercise less force. By use of the eccentric cams this disadvantage is mitigated. The first and second pedal may be positioned between the connecting pulley and intermediate drive system. By positioned between is meant that when the drive system is seen from the side, i.e. perpendicular to the normal drive direction, the connecting pulley and the intermediate drive system are spaced away from each other and the pedals are present in an intermediate position. Suitably the axis of rotation of the one or more connecting pulleys is substantially vertical. In a situation wherein the actuators are handles the connecting cable may run behind the driver as will be illustrated in Figures 8 and 9.

The axis of rotation of the intermediate axle or axles of first and second rotatable means may for example be positioned horizontal. In order to obtain a drive system having a small height it is preferred that the intermediate axle or axles is positioned vertical or substantially vertical. The vertical position of the intermediate axle or axles allows that the drive system can be located close to the lower end of the vehicle. Thus a highly aerodynamic vehicle may be obtained using this drive system. Furthermore most parts of the drive system, except at least the pedals, may be positioned in an enclosed compartment in the floor of the vehicle. This brings it out of sight, which lowers the use barriers and keeps it clean from water and dirt which lowers drastically the need for maintenance. Last but not least it lowers the centre of gravity of the vehicle and allows for precise balancing of the vehicle in all directions.

The drive system as described above will be part of some sort of structure holding together the different parts of the drive system. This structure may suitably be comprised of a frame, a unit body or a monocoque. The material of which the structure is made of may be metal, light weight metals and polymers, such as self- reinforced plastics (SRP) and fibre reinforced polymer material or their combinations. Examples of fibre reinforced polymers, are polymers like polyester or polypropylene reinforced with glass fibre, carbon fibre, nanotubes, nylon fibre, polyethylene fibre, for example Dyneerma® and aramide type fibres, for example Kevlar or Twaron® as well as natural fibres like silk, linen and hemp. Possible polymers may be

thermoplastic or thermoset polymers. The thermoset polymer may be a polyester, a polyurethane or an epoxy resin. The thermoplastic polymer may be polyolefins, polyvinyl chloride, ethylene vinyl acetate, polymethylmethacrylate, polyamide or polyimide. An example of a suitable fibre reinforced polymer is a carbon fibre reinforced polymer. Preferably the polymer is a carbon fibre reinforced polyimide.

The drive system may be used in conjuncture with other drive systems, such as electrical and/or propulsion drive systems. The drive axle may power a wheel of a vehicle, a propeller of a vessel or submarine, and even a rotor of an airplane or helicopter. The drive axle may be connected to an electric generator. The drive axle may also be a connected to a flywheel as part of an exercise apparatus. The two latter applications are examples of how the drive system according to the invention may be used in a stationary application. Suitably the drive system comprises a seat and a backrest to absorb the reaction forces of the user when using the first and second actuators. Suitably the rotating movement of the drive axle is used to drive a drive wheel or wheels of a vehicle, like for example bicycles, tricycles, little cars and other multi wheeled vehicles having 4 or more wheels. It may also be used to drive a track of a track driven vehicle like for example snow mobiles and small tanks. The axis of rotation of the rotating movement as generated by the drive system is substantially horizontal for such applications.

Preferably the drive system is used in a human powered vehicle comprising at least two wheels, wherein at least one of the wheels is a drive wheel connected to the drive axle. A preferred vehicle comprises of two front wheels and one rear wheel, wherein the rear wheel is connected to the drive axle. The front wheels are used for steering.

The invention shall be illustrated by making use of the following Figures. In the figures the elements of the drive system are shown. The frame or any other connection and seats are among other elements of a possible envisaged vehicle not shown for clarity reasons. Figure 1 -3 show the same drive system according to the invention from different viewpoints having a first (1 ) and second (2) pedal mounted for linear reciprocating motion. A first power transmitter cable (3) runs from a fixed point (9) via a pulley (5) connected to first pedal (1 ) to a first eccentric cam (1 1 ). A second power transmitter cable (4) runs from a second fixed point (10) via a pulley (6) connected to second pedal (2) to a second eccentric cam (1 2). Pedals (1 ) and (2) are linked by a connecting cable (7) running via a connecting pulley (8). As shown in the Figure the position of the first and second pedal is between connecting pulley (8) and intermediate drive system (21 ).

The intermediate drive system (21 ) as shown in the Figure consists of first and second eccentric cams (1 1 , 1 2) connected by a common intermediate axle (14). Below cams (1 1 , 12) a third intermediate drive wheel (1 3) is also connected to the common intermediate axle (14). A intermediate power transmitter cable (15) runs from third intermediate drive wheel (1 3) via a freewheel (16) to a pulley (1 9) and back to drive wheel (1 3) via freewheel (17). Freewheel (1 6) and (1 7) are connected to the drive axle (26) of drive wheel (18) of a vehicle. For clarity reasons the other wheels of the vehicle and the structure of the vehicle is not shown in this figure. It will thus be clear that connecting pulley (8), common intermediate axle (14), fixed points (9) and (10), pulley (19) and drive wheel (1 8) will be connected in some manner to said structure. Pulley (19) is connected to the structure by a spring (20) to ensure enough tension in intermediate power transmitter cable (15). Instead of a spring (20) the cable (15) may be provided with a section which is more elastic than the rest of the cable to achieve the same result.

In use the first cam (1 1 ), second cam (12) and third intermediate drive wheel (13) simultaneously rotate and rotate in alternate directions along their common intermediate axle (14) when the first and second pedals are operated in a linear reciprocating motion. This results in that intermediate power transmitter cable (15) will move in alternating directions. The freewheels (1 6) and (1 7) are designed such that when the intermediate power transmitter cable (1 5) moves in a first direction, a rotating movement in a predetermined direction is transferred by one of the freewheels to the axle of the drive wheel (18) and when the intermediate power transmitter cable (1 5) moves in the opposite direction a rotating movement in the same predetermined direction is transferred by the other freewheel to the axle of the drive wheel (1 8).

The above referred to smallest distance between power transmitter cable (3, 4) and intermediate common axle (14) on the cam (1 1 , 12) is between 0.05 and 0.2 m and the above referred to greatest distance is between 0.07 and 0.3 m, wherein the smallest distance is smaller than the greatest distance. The length along which the pedals (1 , 2) can move is suitably between 0.35 and 0.5 m and preferably about 0.4 m.

Figure 4 is an example of how the drive system can be incorporated into a three-wheeled vehicle. Shown is the drive system wherein pedals (1 ) and (2), connecting pulley (8), drive wheel (18), freewheels (16, 17) and intermediate power transmitter cable (1 5) are visible. Further shown are two front wheels (22), a steer (23) and a seat (24). Furthermore an enclosure (25) is shown which encloses most part of the intermediate drive system (21 ) to protect against dirt and water. This Figure also clarifies the advantage of having a vertical or substantial vertical direction for the intermediate axle 14. Because of this orientation it is possible to position the intermediate drive system (21 ) below the seat (24) of the user while still achieving a relatively low structure. Figure 5 is a detailed presentation of the vehicle shown in Figure 4. In this Figure a rail (27) is shown along which pedal (2) can move.

Figure 6 shows a rail (27) for a pedal (2) which results in a slightly arcuate pathway of the pedal (2). The pedal (2) is provided with a pulley (6) and connected to a carriage (28) which runs along the rails (27). In such a design the difference in elevation of the starting position of the pedal (2) and the end position of the pedal (2) may for example be between 0.05 and 0.1 m for a 0.5 m pedal pathway between said starting position and end position.

Figure 7 shows a comparison between a conventional cyclic pedal system having a maximum leverage distance Y and the drive system according to the invention having a smallest leverage distance X. Both systems are compared for one pedal stroke as illustrated in the graph of Figure 7 by the 169° arc of the

conventional pedal system and by the two positions of the pedal (1 ) of the drive system according to the invention. The position of cam (1 1 ) as shown in the Figure 7 corresponds with the first pedal position, i.e. when the pedal 1 is closest to the cam 1 1 . In the graph of Figure 7 the two drive systems are compared wherein the y-axis is the leverage distance (e.g. X), i.e. the force which may be exercised, of the drive system and the x-axis is the angle in sections of 36° of either the rotating pedal of the conventional cyclic pedal system or the rotation of the cam (1 1 ). As can be seen is that the drive system according to the invention provides the user an on average higher leverage during one stroke (white area under the curve) than the conventional pedal system (greyed area under the curve). Furthermore in one pedal stroke of the drive system according to the invention more rotation is achieved. This means that a user can propel itself with a higher efficiency and a greater distance in one pedal stroke as compared to when he or she would travel using a conventional cyclic pedal system. The Figure also shows that when a cam 1 1 is used having a constant diameter X much of the above advantages would also be achieved.

Figure 8 and 9 show a bicycle provided with two pedal actuators (1 , 2) mounted for linear reciprocating motion as in Figures 1 -3. The corresponding numbers refer to the same elements in these Figures. In Figure 8 and 9 the intermediate drive system (21 ) of first and second eccentric cams (1 1 , 12) having their own intermediate axles (14a and 14b). Intermediate drive wheels (52a, 52b (not shown)) are individually connected to each intermediate axle (14a (not shown), 14b) respectively and positioned between eccentric cams (1 1 ) and (12). A first

intermediate power transmitter cable (41 ) runs from the intermediate drive wheel (52a) to a freewheel (43) connected to a drive axle (42). Drive axle (42) is part of rear wheel (45). Pulley (44) directs first intermediate power transmitter cable (41 ) from the intermediate drive wheel (52a) to the freewheel (43). A second intermediate power transmitter cable (46) runs from the intermediate drive wheel (52b) to a freewheel (49) connected to a drive axle (51 ). Double pulleys (47) and (48) guide the second intermediate power transmitter cable (46) from the intermediate drive wheel (52b) to the freewheel (49) and back to the intermediate drive wheel (52b). Drive axle (51 ) is part of front wheel (50).

The bicycle of Figure 8 and 9 is also equipped with handle actuators (31 , 32). This enables the driver to use both arms and legs to propel the bicycle forwards. The handle actuators (31 , 32) can move along a rails (36, 37) respectively. The Handles (31 , 32) are linked by a connecting cable (38) running via connecting pulleys (39, 40). A third power transmitter cable (33) runs from first handle (31 ) to first eccentric cam (1 1 ) via pulley (35). A fourth power transmitter cable (34) runs from second handle pedal (32) via pulley (35) to the second eccentric cam (1 2). In this manner forward actuation of pedal (1 ) and simultaneous backward actuation of handle (32) will rotate cam (1 1 ) and intermediate axle (14a) in one direction. A subsequent forward actuation of pedal (2) and simultaneous backward actuation of handle (31 ) will rotate cam (1 2) and intermediate axle (14b) in the opposite direction.

The alternating directions of the intermediate axles (14a and 14b) are transferred to the freewheels (43) and (49) via the intermediate power transmitter cables (41 , 46) resulting in an alternating forward rotation of drive axles (42, 51 ).

Figure 10 shows a single third intermediate drive wheel (13) of which its radius can be seamlessly altered by the user of the drive system such to achieve gearing. The drive wheel (1 3) consists of a lower wheel (53) non-rotatably fixed to the intermediate axis (14) and an upper wheel (54) which can move in an axial direction along the axis (14). To the lower wheel a number of slide bars (55) are fixed. The slide bars (55) are positioned under and angle and directed towards axis (14) as seen from the lower wheel (53). The slide bars (55) pass the upper wheel (54) though a radial indentation (56) in upper wheel (54). On each slide bar (55) a cable support element (57) is positioned on the part of the slide bar (55) which is between the lower (53) and upper (54) wheel. The cable support element (57) supports intermediate power transmitter cable (15). The cable support element (57) can move along the slide bar (55) thereby seamlessly changing the radius of the third intermediate drive wheel (13). In use the user can change the position of the upper wheel (54) and thereby the radius of the third intermediate drive wheel (13) and thus the gearing. It is foreseen that the upper wheel will move upwards when the user exercises more force. The opposite direction, namely pushing the upper wheel downwards can be done by a pusher of by a weight which, depending on the velocity of the vehicle pushes the upper wheel downwardly. In principle the position of the illustrated lower and upper wheel can be interchanged.

The invention is also directed to such a gearing system comprising of an axis (14) and a cable support wheel mounted on said axis and a power transmittal cable supported by the cable support wheel, wherein the cable support wheel (13) comprises of a lower wheel (53) non-rotatably fixed to the axis (14) and an upper wheel (54) which can move in an axial direction along the axis (14), wherein to the lower wheel a number of slide bars (55) are fixed, which slide bars (55) are positioned under an angle and directed towards axis (14) as seen from the lower wheel (53), wherein the slide bars (55) pass the upper wheel (54) though a radial indentation (56) in upper wheel (54) and wherein on each slide bar (55) a cable support element (57) is positioned on the part of the slide bar (55) which is present between the lower (53) and upper (54) wheel, wherein the cable support element (57) supports the power transmitter cable (15) and wherein the cable support element (57) can move along the slide bar (55) thereby seamlessly changing the radius of the third intermediate drive wheel (13) such to achieve gearing.