Improved transmission system for a pedal vehicle and related control method

Abstract

A transmission system (5; 105) for a pedal vehicle (1) comprising a frame (2) movable on wheels (3) and a pedal transmission (4) operatively connected to at least one of said wheels (3), the pedal transmission (4) comprising a pair of pedals (4'), the transmission system (5; 105) comprising a pedal shaft (11; 111) configured to be operatively connected to the pedals (4'), a crown (27; 129) and an intermediate shaft (15; 115) operatively connected to the crown (27; 129) and configured to cooperate with the pedal transmission (4), the pedal and intermediate shafts (11, 15; 111, 115) being configured to be carried in a rotationally free way by the frame (2), the transmission system (5; 105) comprising a first and a second transmission branch (14, 15; 114, 115) operatively connecting together different elements of the transmission system (5, 105).

Description

[0001] IMPROVED TRANSMISSION SYSTEM FOR A PEDAL VEHICLE AND

[0002] RELATED CONTROL METHOD

[0003] Cross-Reference to Related Applications

[0004] This Patent Application claims priority from Italian Patent Applications No. 102023000016692 filed on August 4, 2023, and No. 102023000026799 filed on December 15, 2023, the entire disclosure of which is incorporated herein by reference.

[0005] Technical Field

[0006] The present invention relates to a transmission system for a pedal vehicle.

[0007] The present invention finds its preferred, though not exclusive, application in a transmission system for hybrid drive bicycles. This application will be referred to hereinafter by way of example.

[0008] State of the Prior Art

[0009] Pedal vehicles, such as bicycles, are increasingly being used as a movement system both for leisure purposes and for reasons of necessity, such as the transport of goods, especially in cities.

[0010] In order to ensure that increasingly longer routes or steeply inclined routes are covered, hybrid drive systems for bicycles are well known.

[0011] In purely mechanical or hybrid drive systems, it is necessary to provide transmission systems which, as is known, allow the selection of different gear ratios between the input and the output of the transmission.

[0012] In particular, gearshift mechanisms equipped with gear wheels are known to be used, wherein some wheels are normally carried idly by the respective support shaft and can be selectively fixed thereto by selection systems to define the gear ratio.

[0013] However, these shifting systems are expensive, bulky, difficult to maintain and clearly cannot provide a high number of gear ratios.

[0014] There is therefore a need to solve the technical issues with regard to the systems of the prior art as reported above.

[0015] The object of the present invention is to meet the above need in an optimized and cost-effective manner.

[0016] Summary of the Invention

[0017] Said object is achieved by means of 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 of the present invention, a preferred embodiment is described below by way of non-limiting example and with reference to the accompanying drawings, wherein:

[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 sectional side view of a transmission system according to a first embodiment of the invention, with parts removed for clarity; and

[0022] • Figure 3 is a schematic functional view of a transmission system according to a second embodiment of the invention.

[0023] Detailed Description of the Invention

[0024] Figure 1 shows, by way of example, a pedal vehicle 1 , such as a bicycle, provided with a frame 2 moving on the ground via a pair of wheels 3.

[0025] The bicycle 1 comprises a transmission 4, as is 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’ that can be operated by the cyclist’s muscular force.

[0026] The bicycle 1 further comprises a transmission system 5 housed in a casing 6 defining a space 7 isolated from the outside and advantageously carried by / integrated with the frame 2.

[0027] As schematized in Figure 1 , advantageously, the transmission system 5, and therefore the casing 6 containing it, are placed next to the pedals 4’. Figures 2 and 3 show two exemplary embodiments of the transmission system 5.

[0028] In the first embodiment in Figure 2, the transmission system 5 comprises a pedal shaft 1 1 rigidly connected, at both ends along a first axis A, to the pedals 4’. The pedal shaft 11 is carried in a rotationally free way by the casing 6 and protrudes from the space 7 through openings 6' obtained in the casing 6.

[0029] 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 according to the rotational direction of the latter in relation to the first axis A.

[0030] The intermediate shaft 15 is carried in a rotationally free way by the casing 6 along a second axis B, preferably parallel to the first axis A.

[0031] Advantageously, the first transmission branch 14 comprises a CVT (Continuous Variable Transmission) shifting system, and better still a continuous belt-driven shifting system. In detail, the first transmission branch 14 comprises a first pulley 16’ and a second pulley 16” carried by the intermediate shaft 15 and the pedal shaft 1 1 , respectively. Advantageously, the first and the second pulley 16', 16" are conical pulleys.

[0032] 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 aforementioned pulleys 16’, 16”.

[0033] Preferably, the first and the second conical pulley 16’, 16” have taper angles equal to each other and in opposite directions to each other. In other words, the diameter of the first pulley 16' decreases along the second axis B, whereas the diameter of the second pulley 16" in such a direction along the first axis A, and vice versa in the opposite direction.

[0034] Also advantageously, one of the first and the second pulley 16', 16" is carried by the respective shaft via a selective coupling mechanism 18, such as a free wheel, whereas the other is carried by the respective shaft in a rigid manner. In detail, the second pulley 16" is carried by the pedal shaft 1 1 via a selective coupling mechanism 18, such as a free, one-way wheel configured to allow rotational coupling of the second pulley 16" when a torque is transmitted from the pedal shaft 1 1 towards the intermediate shaft 15 and to allow the idle rotation of the second pulley 16" in the opposite direction. As a result, the first pulley 16' is carried by the intermediate shaft 15 rotationally integrally therewith.

[0035] The first transmission branch 14 also comprises a variator system 19 configured to vary the transmission ratio value between the pedal shaft 1 1 and the intermediate shaft 15, thus axially varying along the axes A, B the gripping position of the endless transmission element 17.

[0036] In detail, the variator system 19 comprises a carriage actuator 21 configured to slidably engage the endless transmission element 17 and configured to slide on a support 22 and rotate around its own axis concordant with the speed of the endless element 17. Advantageously, the carriage 21 is coupled to the support 22 via a threaded coupling.

[0037] More preferably, the carriage 21 is a nut and the support 22 is a screw, thereby forming a screw-nut coupling which actuates the movement of the endless transmission element 17.

[0038] In detail, the variator system 19 also comprises actuator means 23, such as an electric actuator, configured to rotate the support 22 around its axis, thus moving, according to the rotational direction, the carriage 21 along the axes A, B.

[0039] Accordingly, the carriage 21 can assume an intermediate position between a position of minimum or maximum distance from the casing 6 corresponding to a condition of maximum or minimum transmission ratio in the first transmission branch 14.

[0040] Preferably, the support 22 is carried inclined in a rotatable manner by the casing 6 so that its axis of rotation is parallel to the axis of inclination of the cones of the first and the second pulley 16', 16". The bicycle 1 comprises input means (not shown), such as electromechanical or electronic input means, configured to provide a control signal for controlling the actuator means 23 relating to a request from the cyclist to set a certain transmission ratio in the first transmission branch 14 or through automatic processing as described below.

[0041] The transmission system 5 further comprises a second transmission branch 25 operatively placed in parallel to the first transmission branch 14 and comprising a support shaft 26, a crown 27, and an electric machine M.

[0042] The second transmission branch 25 is configured to mechanically connect the support shaft 26 to the intermediate shaft 15 and these to the output shaft, preferably according to the rotational direction of the latter in relation to the second axis B.

[0043] Preferably, the support shaft 26 is operatively connected to the electric machine M and carried in a rotationally free way by the casing 6 along a third axis C, preferably parallel to the first and second axes A, B. The electric machine M is rigidly carried by the casing 6, so that the stator part is connected to it, and the rotor part to the support shaft 26.

[0044] The electric machine M is electrically connected (by cables, not shown) to power storage means, such as batteries, carried by the frame 2.

[0045] The crown 27 is advantageously carried in a rotationally free way in relation to the casing 6 and protrudes from it through one of the openings 6'. In detail, the crown 27 is housed in a rotationally free way on the pedal shaft 1 1 .

[0046] The crown 27 essentially comprises a pinion 27’ housed outside the space 7 and configured to cooperate with the endless transmission element 4” of the transmission 4 to provide or receive torque to / from the wheels 3.

[0047] Advantageously, the second transmission branch 25 comprises a gear train shifting system, advantageously a gear connecting together the support shaft 26, the crown 27 and the intermediate shaft 15.

[0048] In detail, the second transmission branch 25 comprises a first gear wheel 28 carried by the support shaft 26, a second gear wheel 29 carried by the intermediate shaft 15 and meshing with the first gear wheel 28, and a third gear wheel 31 integral with the crown 27 and meshing with the second gear wheel 29.

[0049] In further detail, the first and the third gear wheel 28, 31 are rigidly carried by the support shaft 26 and the crown 27, respectively, whereas the second gear wheel 29 is carried by the intermediate shaft 15 via a selective coupling mechanism 32, such as a free wheel, configured to allow rotational coupling of the second gear wheel 29 when a torque is transmitted from the intermediate shaft 15 towards the crown 27.

[0050] As a result of the above, the electric machine M is in a configuration “in parallel” in relation to the muscular torque input, i.e. , to the pedal shaft 11 .

[0051] Advantageously, the transmission system 5 also comprises sensor means configured to detect physical quantities relating to the torques transmitted along the elements of the transmission system 5 and consequently control the electric machine M and the variator system 19.

[0052] In detail, the transmission system 5 comprises a torque sensor 35, such as a torquemeter or equivalent, configured to detect the torque at the crown 27. Alternatively, the torque may be detected at the pedal shaft 1 1 .

[0053] Advantageously, the transmission system 5 also comprises a position sensor 36, such as an encoder or equivalent, configured to detect the position of the support shaft 26, or alternatively, on the output shaft.

[0054] Advantageously, the bicycle 1 comprises an electronic unit (not shown) configured to detect the data from the above-mentioned sensor means and / or from the input means and comprising processing means adapted to process said acquired data to consequently control the electric machine and / or the actuator means of the variator system.

[0055] In the second embodiment shown in Figure 3, the transmission system 105 comprises a first transmission branch 1 14 and an intermediate shaft 1 15, the first transmission branch 1 14 is configured to mechanically connect the pedal shaft 1 1 1 to the intermediate shaft 1 15, preferably according to the rotational direction of the latter in relation to the first axis A.

[0056] The intermediate shaft 1 15 is carried in a rotationally free way by the casing along a second axis B, preferably parallel to the first axis A.

[0057] Advantageously, the first transmission branch 1 14 comprises a CVT (Continuous Variable Transmission) shifting system. In detail, the first transmission branch 114 comprises a first pulley 116’ and a second pulley 116” carried by the intermediate shaft 1 15 and the pedal shaft 1 1 1 , respectively. Advantageously, the first and the second pulley 1 16', 116" are conical pulleys, as is known per se in the art.

[0058] The first and the second pulley 116’, 116” are operatively connected to each other by an endless transmission element 1 17, such as a belt or equivalent, configured to cooperate in contact with at least part of the outer surfaces of the aforementioned pulleys 116’, 116”.

[0059] Preferably, the first and the second conical pulley 116’, 116” have taper angles equal to each other and in opposite directions to each other.

[0060] Also advantageously, one of the first and the second pulley 1 16', 1 16" is carried by the respective shaft via a selective coupling mechanism 1 18, such as a free wheel, whereas the other is carried by the respective shaft in a rigid manner. In detail, the second pulley 1 16" is carried by the pedal shaft 1 1 1 via a selective coupling mechanism 1 18, such as a free, one-way wheel configured to allow rotational coupling of the second pulley 1 16" when a torque is transmitted from the pedal shaft 1 11 towards the intermediate shaft 1 15 and to allow the idle rotation of the second pulley 116" in the opposite direction. As a result, the first pulley 1 16' is carried by the intermediate shaft 115 rotationally integrally therewith.

[0061] The first transmission branch 1 14 also comprises a variator system 119 configured to vary the transmission ratio value between the pedal shaft 1 1 1 and the intermediate shaft 1 15, thus axially varying along the axes A, B the gripping position of the endless transmission element 1 17.

[0062] In detail, the variator system 1 19 can be made in various ways, such as for example the one described in the first embodiment, and therefore not described below.

[0063] The transmission system 105 further comprises a second transmission branch 125 operatively placed in parallel to the first transmission branch 1 14 and comprising a support shaft 126 and an electric machine M.

[0064] The second transmission branch 125 is configured to mechanically connect the support shaft 126 to the electric machine M, to the intermediate shaft 1 15 to a crown 129 connected via the endless transmission element 104" to the rear wheel 103".

[0065] In particular, the second transmission branch 125 comprises a first gear 127 connecting the intermediate shaft 1 15 and the support shaft 126. In detail, this first gear 127 comprises a first wheel 127’ carried by the intermediate shaft 115, a second wheel 127" carried by the support shaft 126, and a third, idle gear wheel 127”’ idly supported between the first and the second wheel 127', 127".

[0066] Advantageously, at least one of the first and the second wheel 127', 127" is carried so that it can be selectively disconnected from the respective shaft 1 15, 126, whereas the other is carried fixed to it.

[0067] In the exemplary embodiment described, the second wheel 127" is carried by the support shaft 126 in a fixed way, the first wheel 127' is carried so that it can be selectively disconnected from the intermediate shaft 1 15. In detail, the first wheel 127’ is carried fixed to a portion of the intermediate shaft 115 which can be connected to the remaining part via coupling means 130, such as a clutch or similar means.

[0068] In particular, these coupling means 130 may be interposed, like a selective joint, between the first wheel 127’ and the intermediate shaft 115.

[0069] Clearly, a dual configuration could be created where the coupling means 130 are placed between the second wheel 127” and the support shaft 126. The second transmission branch 125 further comprises a second gear 128 connecting an operating shaft of the electric machine M to the support shaft 126. In detail, this second gear 28 comprises a first wheel 128’ carried by the operating shaft of the electric machine M, a second wheel 128” carried by the support shaft 126. In detail, both wheels 128’, 128” are carried fixedly by the operating shaft of the electric machine M and by the support shaft 126, respectively.

[0070] It can be seen that the support shaft 126 is either carried movably in relation to the pedal shaft 1 11 , separated from it and supported by the casing, or coaxial around it and rotatable.

[0071] Advantageously, the transmission system 105 also comprises sensor means configured to detect physical quantities relating to the speeds transmitted along the elements of the transmission system 105 and consequently control the electric machine M and the variator system 1 19.

[0072] In detail, the transmission system 105 comprises a torque sensor, such as a torquemeter or equivalent, configured to detect the torque at the support shaft 126. Alternatively, the torque may be detected at the pedal shaft 1 1 1.

[0073] Advantageously, the transmission system 105 also comprises a position sensor, such as an encoder or equivalent, configured to detect the position of the support shaft 126.

[0074] As in the first embodiment, the transmission 105 and / or the bicycle 1 comprises an electronic unit (not shown) configured to detect the data from the above-mentioned sensor means and / or from the input means and comprising processing means adapted to process said acquired data to consequently control the electric machine and / or the actuator means of the variator system.

[0075] Advantageously, the bicycle 1 comprises electrical energy storage means, such as batteries, electrically connected to the electric machine M with which to exchange electrical energy depending on the operating mode of the electric machine M as a generator or a motor.

[0076] The operation of the embodiment of the pedal vehicle transmission system according to the invention described above in the first embodiment is as follows.

[0077] In a first, muscular operating condition, the cyclist provides torque via muscular force to the pedal shaft 11 ; the torque is then transmitted to the intermediate shaft 15 via the first transmission branch 14, and from there to the output shaft 27 via a portion of the second transmission branch 25. The cyclist can adjust the transmission ratio using the gear selection means through a range of transmission intervals between a lower and an upper shifting limit, and consequently the actuator means 23 control the position of the carriage 21 along the support 22 by varying the transmission ratio between the pedal shaft 1 1 and the intermediate shaft 15.

[0078] In a second, merely assisted operating condition, the electric machine M provides torque to the support shaft 26; the torque is then transmitted via the second transmission branch 25 directly to the output shaft 27 and therefore to the wheels 3. In this condition, the freewheel mechanism 18 keeps the second pulley 16" idle in relation to the pedal shaft 1 1 .

[0079] In a third, boost operating condition, both the electric machine M and the cyclist provide torque towards the output shaft 27 to the wheels 3. In this condition, the provided torque is added to the second gear wheel 29 because both the transmission branches 14, 25 are engaged as in the first and second operating conditions.

[0080] In a fourth, regenerative braking operating condition, the cyclist keeps the pedals in a stable position and the pinion is driven by the wheels 3, thus bringing into rotation the third gear wheel 31 , which drives the second gear wheel 29, in this case carried idle on the intermediate shaft 15 and therefore dragging the first gear wheel 28, which rotates the electric machine M, which can then generate electrical energy by braking the wheels 3.

[0081] The operation of the embodiment of the pedal vehicle transmission system according to the invention described above in the second embodiment is as follows. In a first, muscular operating condition, the cyclist provides torque via muscular force to the pedal shaft 11 1 ; the torque is then transmitted to the intermediate shaft 1 15 via the first transmission branch 1 14, and from there to the support shaft 126, hence to the crown 129, via a portion of the second transmission branch 125. In this condition, in fact, the first gear wheel 127’ is integral with the intermediate shaft 1 15 as the coupling 130 is closed. The cyclist can adjust the transmission ratio using the gear selection means through a range of transmission intervals between a lower and an upper shifting limit, and consequently the variator system 1 19 can vary the transmission ratio between the pedal shaft 1 1 1 and the intermediate shaft 1 15.

[0082] In a second, merely assisted operating condition, the electric machine M provides torque to the support shaft 126 via the second gear 128, and hence to the crown 129. In this condition, the freewheel mechanism 1 18 keeps the second pulley 1 16" idle in relation to the pedal shaft 1 1 1. In addition, the coupling 130 is open so as to decrease the passive inertia on the support shaft 126.

[0083] In a third, regenerative braking operating condition, the cyclist keeps the pedals in a stable position, the crown 129 is driven by the wheels 3, thus bringing into rotation the support shaft 126 which, via the second gear 128, bring into rotation the electric machine M, which can then generate electrical energy by braking the wheels 3. In this condition, too, the coupling 130 is open so as to decrease the passive inertia on the support shaft 126.

[0084] In a fourth, boost operating condition, both the electric machine M and the cyclist provide torque towards the support shaft 126, thus via the crown 129 to the wheels 3. In this condition, the provided torque is added to the support shaft 126 and the coupling 130 is closed.

[0085] According to the above, the invention also relates to a control method for a pedal vehicle transmission system as described above and comprising the steps of:

[0086] • i) Acquiring the data from the sensor means and / or the input means; • ii) Processing the data acquired in step i) to determine an operating configuration of the electric machine and / or the variator system;

[0087] • iii) Controlling the operating configuration of the electric machine and / or the transmission ratio in the first transmission branch through the variator system according to the processing in step ii).

[0088] 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 elaborated in step ii).

[0089] In particular, the variator system allows the transmission ratio in the first transmission branch to be continuously varied between a minimum value and a maximum value.

[0090] In detail, in the second embodiment, when the electric machine M is operating as a motor, the electronic unit, by receiving as input the speed data of the second wheel 127" of the first gear 127 and having stored the transmission ratio of the second gear 128, can control the electric machine so as to rotate the second wheel 128" at the same speed as the second wheel 127" of the first gear 127.

[0091] The advantages of a transmission system, a pedal vehicle and a control method according to the invention are clear from the foregoing.

[0092] By providing a transmission branch equipped with a transmission ratio varying continuously between a minimum and a maximum value, a versatile transmission system can be provided and easily adapted to any required torque profile.

[0093] In addition, the proposed system is particularly compact and less expensive than a gear system and can be controlled more easily.

[0094] Furthermore, the arrangement of the second transmission branch in parallel with the first transmission branch and with a pair of free wheels allows multiple operating configurations to be achieved without the need for complex gearshift mechanisms. In detail, the transmission system is optimized for any muscular, regenerative, boost or merely electrical operating configuration.

[0095] The detection of torque and speed also provides automatic and optimized control of the electric machine. Lastly, it is clear that modifications and variations may be made to the transmission system, the pedal vehicle and the control method according to the present invention, without however departing from the scope of protection defined by the claims.

[0096] For example, the elements constituting the first and second transmission branches can be exchanged with elements that are equivalent or of different construction compared to the above description.

[0097] Clearly, the selective mechanisms, described here as freewheeling, may be of the “active” type, i.e. , actively controllable and not merely mechanical as described, such as clutches. Furthermore, the proposed gear transmission can be applied to any type of pedal vehicle.

Claims

CLAIMS1.- A transmission system (5; 105) for a pedal vehicle (1 ) comprising a frame (2) movable on wheels (3) and a pedal transmission (4) operatively connected to at least one of said wheels (3), said pedal transmission (4) comprising a pair of pedals (4'), said transmission system (105) comprising a pedal shaft (11 , 11 1 ) configured to be operatively connected to said pedals (4'), a crown (27; 129) and an intermediate shaft (1 15) operatively connected to said crown (29) and configured to cooperate with said pedal transmission (4), said pedal and intermediate shafts (1 1 , 15; 11 1 ; 1 15) being configured to be carried in a rotationally free way by said frame (2), said transmission system (5; 105) comprising a first transmission branch (14; 1 14) connecting said pedal shaft (1 1 ; 1 1 1 ) to said intermediate shaft (15; 1 15), said first transmission branch (14; 114) comprising a CVT-type / continuous shifting system, said transmission system (5; 105) comprising an electric machine (M) and a support shaft (26) operatively connected to said electric machine (M) configured to be carried by said frame (2), said transmission system (5; 105) further comprising a second transmission branch (25; 125) connecting together said support shaft (26; 126), said intermediate shaft (15; 115) and said crown (29), wherein said second transmission branch (25; 125) being operatively placed in parallel with respect to said first transmission branch (14; 1 14).2.- The transmission system according to claim 1 , wherein said CVT / continuous shifting system comprises a first and a second pulley (16’, 16”; 116’, 116”) respectively carried by said intermediate shaft (15; 115) and said pedal shaft (1 1 ; 1 1 1 ), and an endless transmission element (17; 1 17) operatively connecting said first and second pulleys (16’, 16”; 116’, 116”), said first and second pulleys (16’, 16”; 116’, 116”) being conical pulleys.3.- The transmission system according to claim 2, wherein said first pulley (16’; 116’) is rigidly carried by said intermediate shaft (15; 115) and wherein said second pulley (16”; 116”) is carried by said pedal shaft (11 ; 111 ) through aselective coupling mechanism (18; 118) configured to make said second pulley (16”; 116”) rotationally integral with said pedal shaft (11 ; 111 ) when a torque is transmitted from the latter towards said intermediate shaft (15; 115).4.- The transmission system according to one of claims 2 or 3, further comprising a variator system (19; 1 19) configured to vary the transmission ratio between said first and second pulleys (16’, 16”; 116’, 116”).5.- The transmission system according to any one of the preceding claims, wherein said second transmission branch (25) comprises a first gear wheel (28) carried by said support shaft (26), a second gear wheel (29) carried by said intermediate shaft (15) and meshing with said first gear wheel (28) and a third gear wheel (31 ) carried by said output shaft (27) and meshing with said second gear wheel (29).6.- The transmission system according to claim 5, wherein said first and third gear wheels (28, 31 ) are rigidly carried by the respective shafts and wherein said second gear wheel (29) is carried by said intermediate shaft (15) through a selective coupling mechanism (32) configured to make said second gear wheel (29) rotationally integral with said intermediate shaft (15) when a torque is transmitted from the latter towards said output shaft (27).7.- The transmission system according to one of claims 1 to 4, wherein said second transmission branch (125) comprises a first gear (127) connecting said intermediate shaft (1 15) to said support shaft (126), and a second gear (128) connecting said electric machine (M) to said support shaft (126).8.- The transmission system according to claim 7, wherein said first gear (127) comprises a first gear wheel (127') carried by said intermediate shaft (115), a second gear wheel (127”) carried by said support shaft (26), and an idle wheel (127’”) meshing with said first and second gear wheels (127’, 127”).9.- The transmission system according to claim 8, wherein one of said first gear wheel (127’) and said second gear wheel (127”) can be selectively connected to the shaft supporting it via coupling means (130), and wherein theother of said first gear wheel (127’) and said second gear wheel (127”) is rigidly carried by the shaft supporting it.10.- The transmission system according to claim 9, wherein said second gear (128) comprises a first and a second gear wheel (128’, 128”) rigidly carried by an operating shaft of said electric machine (M) and by said support shaft (126), respectively.11.- The transmission system according to any one of the preceding claims, further comprising sensor means suitable for detecting physical quantities indicative of the torques flowing towards said support shaft (26).12.- The transmission system according to claim 1 1 , wherein said sensor means comprise a torque sensor and / or a position sensor.13.- The transmission system according to claim 1 1 or 12, when dependent on claim 4, comprising input means configured to provide a control signal for controlling said variator system (19).14.- The transmission system according to claims 11 or 13 comprising an electronic unit configured to detect the data from said sensor means and / or from said input means and comprising processing means adapted to process said acquired data to control said electric machine (M) and / or said variator system (1 19) accordingly.15.- A pedal vehicle (1 ) comprising a frame (2) movable on wheels (3), a pedal transmission (4) operatively connected to at least one of said wheels (3) and a transmission system (5; 105) operatively connected to said pedal transmission (4) according to one of the preceding claims.16.- The pedal vehicle according to claim 15 when dependent on one of claims from 1 to 14, comprising an electronic unit configured to detect the data from said sensor means and / or from said input means and comprising processing means adapted to process said acquired data to control said electric machine (M) and / or said variator system (19) accordingly17.- A control method for controlling a pedal vehicle transmission systemaccording to claims 15 or 16, comprising the steps of:• i) Acquiring the data from said sensor means and / or said input means;• ii) Processing the data acquired in step i) to determine an operating configuration of the electric machine and / or the variator system;• iii) Controlling the operating configuration of the electric machine and / or the transmission ratio in the first transmission branch through the variator system according to the processing in step ii).18.- The method according to claim 17, 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).19.- The method according to one of claims 17 or 18 when dependent on claim 10, wherein said electric machine (M), when controlled as a motor, is controlled by said electronic unit in order to bring said second wheel (128") of said second gear (128) to the same rotational speed as said second wheel (127”) of said first gear (127).

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