Improved transmission system for pedal vehicle and related control method

Abstract

Transmission system (5) for a pedal vehicle (1) comprising a frame (2) movable on wheels (3) and a pedal transmission (4) operationally connected to at least one of the wheels (3), the pedal transmission (4) comprising a pair of pedals (4' ), the transmission system (5) comprising a pedal shaft (11) configured to be operationally connected to the pedals (4' ), a support shaft (26) and an intermediate shaft (15) operationally connected to the pedal transmission (4), the pedal and intermediate shafts (11, 15) being configured to be carried in a rotationally free manner by the frame (2), the support shaft (26) being carried rotationally free with respect to the pedal shaft (11) and the intermediate shaft (15), the transmission system (5) comprising a first transmission branch (14) connecting the pedal shaft (11) to the intermediate shaft (15), and a second transmission branch (5) connecting an electric machine (M) to the wheel (3), the transmission (5) being configured to operate in forward and reverse gear depending on the different operational configurations.

Description

[0001] IMPROVED TRANSMISSION SYSTEM FOR PEDAL VEHICLE AND RELATED CONTROL METHOD

[0002] Cross-Reference to Related Applications

[0003] This Patent Application claims priority from Italian Patent Application No . 102023000026805 filed on December 15 , 2023 , the entire disclosure of which is incorporated herein by reference .

[0004] Technical Sector

[0005] The present invention relates to a transmission system for a pedal vehicle .

[0006] The present invention has its preferred, although not exclusive , application in a transmission system for a hybrid traction bicycle . Reference will be made to thi s application below by way of an example .

[0007] Prior Art

[0008] Pedal vehicles , such as a bicycle , are being increasingly used as a means of travel for reasons of both leisure and need, such as the transport of goods , particularly in cities .

[0009] In order to guarantee travel on increasingly longer or heavily inclined routes , hybrid traction systems for bicycles are known .

[0010] In purely mechanical or hybrid traction systems , it is necessary to provide for transmission systems that , as known, allow di f ferent gear ratios between the transmission input and output to be selected .

[0011] In particular, it is known to use gear mechanisms provided with cogwheel gears , in which several wheels are normally carried idly by the respective support shaft and selectively fixable to them by means of selector systems to define the gear ratio .

[0012] However, these gear systems are costly, cumbersome , di fficult to maintain and, clearly, cannot provide a high number of gear ratios .

[0013] Furthermore , the existing gear systems are not particularly suited to providing operating methods of the bicycle in reverse , a useful feature in certain situations .

[0014] There is therefore a need to solve the technical problems with respect to the systems in the prior art as described above .

[0015] The obj ect of the present invention is therefore to satis fy the needs indicated here above , in an optimal and economical manner .

[0016] Summary of the Invention

[0017] The aforesaid obj ect is achieved by a transmission system, a pedal vehicle and a control method as claimed in the appended claims .

[0018] Brief Description of the Drawings

[0019] For a better understanding o f the present invention, a preferred embodiment is described below, by way of nonlimiting example , with reference to the appended drawings , in which :

[0020] • Figure 1 is a schematic side view of a bicycle comprising a transmission system according to the invention .

[0021] • Figure 2 is a schematic representation of the transmission system according to the invention in a first operating configuration; Figure 3 is a schematic representation of the transmission system according to the invention in a second operating configuration; Figure 4 is a schematic representation of the transmission system according to the invention in a third operating configuration; and Figure 5 is a schematic representation of the transmission system according to the invention in a fourth operating configuration .

[0022] Detailed Description of the Invention

[0023] Figure 1 shows , by way of example , a pedal vehicle 1 , such as a bicycle , provided with a frame 2 movable on the ground by means of a pair of wheels 3 , speci fically a front wheel 3 ' and a rear wheel 3 ' ’ .

[0024] The bicycle 1 comprises a transmission 4 , as known a chain / belt transmission or equivalent , comprising an endless transmission element 4 ' ’ , such as the chain / belt or equivalent , and a pair of pedals 4 ' operable by means of the muscle strength of the cyclist .

[0025] The bicycle 1 further comprises a transmission system 5 housed in a frame (not shown) defining a space isolated from the outside and advantageously carried by the frame 2 / integrated with it .

[0026] As schematically shown in Figure 1 , advantageously, the transmission system 5 is positioned at the pedals 4 ' .

[0027] With references to Figures 2 to 5 , a transmission system 5 is shown that comprises a pedal shaft 11 rigidly connected on both ends along a first axis A to the pedals 4 ' . The pedal shaft 11 is carried in a rotationally free manner by the frame .

[0028] The transmission system 5 comprises a first transmission branch 14 and an intermediate shaft 15, the first transmission branch 14 is configured to mechanically connect the pedal shaft 11 to the intermediate shaft 15, preferably as a function of the direction of rotation of the latter with respect to the first axis A.

[0029] The intermediate shaft 15 is carried rotationally free from the frame along a second axis B, preferably parallel to the first axis A.

[0030] Advantageously, the first transmission branch 14 comprises a "CVT" (continuous variable transmission) gear system. In detail, the first transmission branch 14 comprises a first pulley 16' and a second pulley 16' ’ carried respectively by the intermediate shaft 15 and by the pedal shaft 11. Advantageously, the first and the second pulley 16' , 16' ’ are conical pulleys, as known in the prior art.

[0031] The first and the second pulley 16' , 16' ' are operatively connected to each other by an endless transmission element 17 such as a belt or equivalent, configured to cooperate in contact with at least part of the outer surfaces of the aforesaid pulleys 16' , 16' ' .

[0032] Preferably, the first and the second conical pulleys 16' , 16' ’ have taper angles equal to each other and in the opposite direction to each other.

[0033] In particular, both the first and second pulley 16' , 16' ' are carried by the respective shaft rigidly. Alternatively, both or one of the pulleys , such as the second pulley 16 ' ' , may be carried by means of a coupling system (not shown) configured to connect it selectively to the respective shaft , therefore in the aforesaid case by the pedal shaft 11 .

[0034] The first transmission branch 14 also comprises a variator system 19 configured to vary the transmission ratio value between the pedal shaft 11 and the intermediate shaft 15 , axially varying along the axes A, B the gripping position of the endless transmission element 17 .

[0035] In detail , the variator system 19 may be obtained in various ways and is therefore not described below .

[0036] The transmission system 5 further comprises a second transmission branch 25 operatively positioned in parallel to the first transmission branch 14 and comprising a support shaft 26 and an electric machine M .

[0037] The second transmission branch 25 is configured to mechanically connect the support shaft 26 to the electric machine M, to the intermediate shaft 15 at a crown 29 connected by means of the endless transmission element 4 ' ’ to the rear wheel 3 ' ’ .

[0038] In particular, the second transmission branch 25 comprises a first gear 27 connecting the intermediate shaft 15 and the support shaft 26 . In detail , said first gear 27 comprises a first wheel 27 ' carried by the intermediate shaft 15 , a second wheel 27 ' ’ carried by the support shaft 26 and a third toothed wheel 22 ’ ’ ’ of return, supported idling between the first and the second wheel 27 ' , 27 ’ ’ .

[0039] Advantageously, at least one of the first and the second wheel 27 ' , 21 ' ' is carried selectively disconnectible from the respective shaft 15 , 26 while the other is carried fixed to it .

[0040] In the example o f an embodiment described, the f irst wheel 21 ' is carried fixed by the intermediate shaft 15 and the second wheel 21 ’ ’ is carried in a manner to be selectively disconnectible from the support shaft 26 . In detail , it is carried in a selectively connectible manner via coupling means 30 interposed, as a selective j oint or a clutch, between it and the support shaft 26 .

[0041] Clearly, a dual configuration could be obtained, where the coupling means 30 are positioned between the first wheel 21 ’ and the intermediate shaft 15 .

[0042] The second transmission branch 25 further comprises a second gear 28 connecting an operating shaft of the electric machine M to the support shaft 26 . In detail , said second gear 28 comprises a first wheel 28 ' carried by the operating shaft of the electric machine M, a second wheel 28 ' ’ carried by the support shaft 26 . In detail , both wheels 28 ' , 28 ' ’ are carried fixed respectively by the operating shaft of the electric machine M and by the support shaft 26 .

[0043] It is noted that the support shaft 26 is carried movable with respect to the pedal shaft 11 , separate from it and supported by the frame or coaxial around it and rotatable .

[0044] Advantageously, the transmission system 5 also comprises sensor means configured to detect physical quantities relating to the speeds transmitted along the elements of the transmission system 5 and to consequently control the electric machine M and the variator system 19 . In detail , the transmission system 5 comprises a torque sensor, such as a torque meter or equivalent , configured to detect the torque at the support shaft 26 . Alternatively, the torque at the pedal shaft 11 could be detected .

[0045] Advantageously, the transmission system 5 also comprises a position sensor, such as an encoder or equivalent , configured to detect the position of the support shaft 26 .

[0046] Advantageously, the bicycle 1 comprises an electronic unit (not shown) configured to detect the data from said sensor means and / or from said input means and comprising processing means suitable for processing such data acquired to consequently control the electric machine and / or the actuator means of the variator system .

[0047] Advantageously, the bicycle 1 comprises electric energy storage means , such as batteries , electrically connected to the electric machine M in order to exchange electric energy with it , as a function of the operating methods of the electric machine M, such as a generator or motor .

[0048] In particular, the electronic unit controls the transmission 5 in a manner to be able to operate according to the following configurations , alternative to each other :

[0049] - A purely muscular configuration where the torque is supplied by the pedal shaft 11 to the crown 29 , both in forward and reverse gear ;

[0050] - A purely electric configuration where the torque is supplied by the electric machine M to the crown 29 both in forward and reverse gear ;

[0051] - A hybrid configuration where the torque is supplied both by the pedal shaft 11 and by the electric machine M to the crown 29 , possibly both in forward and reverse gear ; or

[0052] - A regenerative configuration where torque is supplied by the crown 29 towards the electric machine M to generate electric energy, braking the bicycle 1 .

[0053] Operation of the embodiment of the transmission system for a pedal vehicle according to the invention described above is as follows .

[0054] In a first operating condition ( Figure 2 ) , muscular, the cyclist supplies torque through muscle strength to the pedal shaft 11 , which is transmitted via the first transmission branch 14 to the intermediate shaft 15 and from here via part of the second transmission shaft 25 to the support shaft 26 and therefore to the crown 29 . In such condition, in fact , the first toothed wheel 27 ' is integral with the intermediate shaft 15 , as the coupling 30 is closed . The cyclist can adj ust the transmission ratio via the gear selection means , through a set of transmiss ion ranges between a lower gear limit and an upper gear limit and consequently the variator system 19 can vary the transmission ratio between the pedal shaft 11 and intermediate shaft 15 .

[0055] In a second operating condition, purely assisted ( Figure 3 ) , the electric machine M supplies torque to the support shaft 26 via the second gear 28 and therefore to the crown 29 . The coupling means 30 maintain the second toothed wheel disconnected 27 ’ ’ , so as to reduce the passive inertia on the support shaft 26 .

[0056] In a third operating condition, of regenerative braking ( Figure 4 ) , the cyclist maintains the pedals in a stable position, the crown 29 is dragged by the wheel s 3 rotating with it the support shaft 26 that , by means of the second gear 28 , rotates the electric machine M, which can therefore produce electric energy, braking the wheels 3 . In this condition as well , the coupling 30 is open, so as to reduce the passive inertia on the support shaft 26 .

[0057] In a fourth operating condition, of boost ( Figure 5 ) , both the electric machine M and the cycl ist supply torque towards the support shaft 26 , therefore via the crown 29 to the wheels 3 . In this condition, the torque supplied is summed on the support shaft 26 and the coupling 30 is closed .

[0058] The configuration of Figure 2 can also be used for an operating condition in muscular reverse .

[0059] In particular, in this configuration, the cyclist can supply torque , by rotating in a reverse direction to the direction of travel , to the pedal shaft 11 and, in this manner, thanks to the fact that the gear 27 compri ses three toothed wheels , can return the torque in that backward direction of rotation directly to the support shaft 26 and therefore to the rear wheel 3 ' ’ , taking the bicycle 1 into reverse .

[0060] The configuration of Figure 3 can also be used for an operating condition in electric traction reverse . In this condition, the electric machine M is controlled to rotate the support shaft 26 , but in the reverse direction with respect to the purely electric travel condition described above, reversing the bicycle 1 .

[0061] Clearly, when the electric machine M is activated simultaneously with the muscular reverse , it is possible to obtain a boost reverse condition, i . e . one in which the torque at the support shaft , in reverse direction to the rear wheel 3 ' ' , is supplied both by the pedal shaft 11 and by the electric machine M .

[0062] According to what is illustrated above , the invention also relates to a control method for a transmission system for a pedal vehicle as described above and comprising the steps of : i ) Acquire data from the sensor means and / or the input means ; ii ) Process the data acquired in step i ) to determine an operating configuration of the electric machine and / or the variator system; iii ) Check the operating configuration of the electric machine and / or the transmission ratio in the first transmission branch via the variator system according to the processing in step ii ) .

[0063] In particular, the operating configuration of the electric machine can comprise operation as an electric generator or as an electric motor at a torque value processed in step ii ) .

[0064] In particular, the transmission ratio in the first transmission branch can be varied continuously between a minimum value and a maximum value thanks to the variator system .

[0065] In detail , when the electric machine is operating as a motor, the electronic unit , receiving in input the speed data of the second wheel 27 ' ’ of the first gear 27 , having stored the transmission ratio of the second gear 28 , can control the electric machine so as to rotate the second wheel 28 ' ’ at the same speed as the second wheel 27 ' ’ of the first gear 27 .

[0066] The advantages o f a transmission system of a pedal vehicle and a control method according to the invention are clear from the above . Thanks to the particular configuration of the two transmission branches and the coupling means , it is possible to allow operation according to di f ferent operating profiles in both forward and reverse gear .

[0067] In addition, the fact of providing a transmission branch having a transmission ratio continually variable between a minimum and a maximum value allows a transmission system that is versatile and easily adaptable to any torque profile necessary to be provided .

[0068] Furthermore , the proposed system is particularly compact and less costly than a gear system and more easily controllable .

[0069] In addition, the arrangement of the second transmission branch in parallel to the first transmission branch, the freely rotating mechanism and the coupling means , allows multiple operating configurations to be obtained without the need for complex gear mechanisms .

[0070] In detail , the transmission system is optimised for any muscular, regenerative , boost or purely electric operating configuration, in forward or in reverse .

[0071] Thanks to detection of the torque and speed, it is also possible to control the electric machine in an automatic and optimal manner .

[0072] In conclusion, it is clear that changes and variants can be made to the transmission system, the pedal vehicle and the control method according to the present invention without thus deviating from the scope of protection as defined by the claims . For example, it is possible to vary the elements constituting the first and the second transmission branch with equivalent or differently constructed elements to what is described.

[0073] Clearly, the selective mechanisms, described here as freely rotating, can be of the "active" type, i.e. controllable actively and not merely mechanically as described, as clutches .

[0074] In addition, the gear transmission proposed can be applied to any type of pedal vehicle.

Claims

CLAIMS1. Transmission system (5) for a pedal vehicle (1) comprising a frame (2) movable on wheels (3) and a pedal transmission (4) operationally connected to at least one of said wheels (3) , said pedal transmission (4) comprising a pair of pedals (4' ) , said transmission system (5) comprising a pedal shaft (11) configured to be operationally connected to said pedals (4' ) , a support shaft (26) and an intermediate shaft (15) operatively connected to said pedal transmission (4) , said pedal and intermediate shafts (11, 15) being configured to be carried in a rotationally free manner by said frame (2) , said support shaft (26) being carried rotationally free with respect to said pedal shaft (11) and said intermediate shaft (15) , said transmission system (5) comprising a first transmission branch (14) connecting said pedal shaft (11) to said intermediate shaft (15) , said transmission system further comprising an electric machine (M) , said transmission system (5) further comprising a second transmission branch (25) connecting together said intermediate shaft (15) , said electric machine (M) and said support shaft (26) , said first and second transmission branches (14, 25) being configured to allow the operation of said transmission alternatively in the following configurations:- A purely muscular configuration where the torque is supplied by said pedal shaft (11) to said wheel (3) , both in forward and reverse gear;- A purely electric configuration where the torque is supplied by said electric machine (M) to said wheel (3) both in forward and reverse gear;- A hybrid configuration where the torque is supplied both by said pedal shaft (11) and by said electric machine (M) to said wheel, both in forward and reverse gear;- A regenerative configuration where torque is supplied bysaid wheel (3) towards said electric machine (M) to generate electrical energy.2.- Transmission system according to claim 1, wherein said first transmission branch (14) comprises a continuous / CVT type gear system.3.- Transmission system according to claim 1 or 2, wherein said support shaft (26) carries a crown (29) connected to said pedal transmission (4) , said support shaft (26) being coaxial to said shaft of pedal (11) .4.- Transmission system according to claim 2, wherein said continuous gearbox / CVT type system comprises a first and a second pulley (16', 16' ' ) respectively carried by said intermediate shaft (15) and said drive shaft pedal (11) and an endless transmission element (17) operatively connecting said first and second pulleys (16', 16' ' ) .5.- Transmission system according to claim 4, in which said first and second pulleys (16', 16' ' ) are each rigidly carried by the respective shaft (11, 15) .6.- Transmission system according to one of claims 4 or 5, further comprising a variator system (19) configured to vary the transmission ratio between said first and second pulley(16' , 16' ' ) .7.- Transmission system according to one of the previous claims, in which said second transmission branch (25) is operationally placed in parallel with respect to said first transmission branch (14) .8.- Transmission system according to one of the previousclaims, in which said second transmission branch (25) comprises a first gear (27) connecting said intermediate shaft (15) to said support shaft (26) and a second gear (28) connecting said electric machine (M) to said support shaft (26) .9.- Transmission system according to claim 8, in which said first gear (27) includes a first toothed wheel (27' ) carried by said intermediate shaft (15) , a second toothed wheel (27' ' ) carried by said shaft support (26) and an idler wheel (27' ' ' ) meshing with said first and second toothed wheels (27', 27' ' ) .10.- Transmission system according to claim 8, in which said one of said first toothed wheel (27' ) and said second toothed wheel (27' ' ) can be selectively connected to the respective shaft via coupling means (30) and the other between said first toothed wheel (27' ) and said second toothed wheel (27' ' ) are rigidly carried by the respective shaft.

11. - Transmission system according to claim 10, in which said second gear (28) includes first and second toothed wheels (28', 28' ' ) rigidly carried respectively by an operating shaft of said electric machine (M) and said shaft support (26) .12.- Transmission system according to one of the previous claims, further comprising sensor means suitable for detecting physical quantities indicative of the torques flowing on said support shaft (26) .13.- A transmission system according to claim 12, wherein said sensor means comprises a torque sensor and / or a position sensor .

14. - Transmission system according to claim 12 or 13, whendependent on claim 4, comprising input means configured to provide a control signal for controlling said variator system (19) .15.- Transmission system according to claims 12 or 13, in combination according to claim 14, comprising an electronic unit configured to detect data from said sensor means and / or from said input means and comprising processing means suitable for processing such data acquired to consequently control said electric machine (M) and / or said variator system (19) .16.- Pedal vehicle (1) comprising a frame (2) movable on wheels (3) , a pedal transmission (4) operationally connected to at least one of said wheels (3) and a transmission system (5) operationally connected to said pedal transmission (4) according to one of the previous claims.17.- Pedal vehicle according to claim 15 when dependent on one of claims 1 to 14, comprising an electronic unit configured to detect data from said sensor means and / or from said input means and comprising processing means suitable for process such acquired data to consequently control said electric machine (M) and / or said variator system (19) .18.- Method of controlling a pedal vehicle transmission system according to claims 15 or 17, comprising the steps of: i) Acquire data from said sensor means and / or said input means ; ii) Process the data acquired in step i) to determine an operating configuration of the electric machine and / or the variator system; iii) Check the operating configuration of the electric machine and / or the transmission ratio in the first transmission branch via the variator system according to the processing in step ii) .19.- Method according to claim 18, wherein the operating configuration of the electric machine (M) can comprise operation as an electric generator or as an electric motor at a torque value elaborated in step ii) .20.- Method according to claim 18 or 19, wherein the gear ratio can be varied continuously between a minimum value or a maximum value of gear ratio.21.- Method according to one of claims 18 to 20, wherein said electric machine, when controlled by a motor, is controlled by said electronic unit to bring said second wheel (28' ' ) of said second gear (28) to the same speed rotation of said second wheel (27' ' ) of said first gear (27) .

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