ELECTRICALLY-ASSISTED VEHICLE PROPULSION SYSTEM

Abstract

The invention relates to a propulsion system (1) for a pedal vehicle. The propulsion system (1) comprises a power unit (1) allowing the power originating from a bottom-bracket axle (2) to be combined with the power from two motors (40, 50), a first deformable transmission element (23) allowing the transmission of power to the rear wheel (73) and a casing assembly (19) enclosing particularly the first deformable transmission element (23) and the power unit (1), with the exception of part of the bottom-bracket axle (2).

Claims

1.-18. (canceled)

19. A propulsion system for a pedal vehicle and comprising: a first deformable transmission element arranged to drive a rear wheel of the pedal vehicle; a powertrain comprising: a crankset axle arranged to rotate about a first axis of rotation, a main output plate arranged to drive the first deformable transmission element, a first motor, a second motor, an epicyclic gear train comprising a first input element, an output element and a sun, the crankset axle and the second motor being connected to the epicyclic gear train via the first input element so as to form a first input of the epicyclic gear train, the first motor being connected to the epicyclic gear train via the sun so as to form a second input of the epicyclic gear train, the output element connecting the epicyclic gear train to the main output plate so as to form an output of the epicyclic gear train, and the first deformable transmission element being arranged to transmit power between the powertrain and the rear wheel of the pedal vehicle; and a casing assembly; a rear sprocket; wherein the main output plate, the first input element, the output element and the sun are arranged so as to rotate about a same second axis of rotation different from the first axis of rotation; the powertrain comprises: a secondary output plate arranged to rotate about the first axis of rotation and meshed to the first deformable transmission element, a speed reduction system maintaining the direction of rotation for transmitting a rotation between the crankset axle and the first input element; and the first deformable transmission element, a portion of the crankset axle, the main output plate, the first motor, the second motor, the epicyclic gear train, the secondary output plate, and the rear sprocket are within the casing assembly.

20. The propulsion system according to claim 19, further comprising a tensioning roller arranged to tension the first deformable transmission element.

21. The propulsion system according to claim 19, wherein the casing assembly comprises a transmission casing which encloses the first deformable transmission element, the transmission casing being arranged to be located on one side only of the rear wheel.

22. The propulsion system according to claim 19, wherein the casing assembly is arranged to ensure alone the mechanical attachment between the rear wheel and a frame of the pedal vehicle.

23. The propulsion system according to claim 19, wherein the second motor is connected to the first input element of the epicyclic gear train via a third deformable transmission element.

24. The propulsion system according to claim 19, further comprising a rear sensor arranged to measure the speed of the rear wheel and located within the casing assembly.

25. The propulsion system according to claim 19, wherein the main output plate is integral with the output element.

26. The propulsion system according to claim 19, further comprising a first freewheel arranged to prevent the secondary output plate from rotating slower than the crankset axle when the crankset axle rotates in the normal pedalling direction.

27. The propulsion system according to claim 19, wherein the powertrain further comprises a second freewheel arranged to prevent a drive of the crankset axle by the second motor in a rotational direction corresponding to a forward motion of the pedal vehicle.

28. The propulsion system according to claim 19, wherein the powertrain further comprises a rear wheel freewheel arranged to prevent the rear sprocket from rotating faster than the rear wheel when the crankset axle rotates in the normal pedalling direction which corresponds to a forward motion of the pedal vehicle.

29. The propulsion system according to claim 19, wherein the main output plate is smaller than the secondary output plate.

30. The propulsion system according to claim 29, wherein the rear sprocket is smaller than the secondary output plate and larger than the main output plate.

31. The propulsion system according to claim 19, wherein the first input element is a ring gear of the epicyclic gear train and the output element is a planet carrier of the epicyclic gear train.

32. The propulsion system according to claim 19, wherein the first input element is a planet carrier of the epicyclic gear train and the output element is a ring gear of the epicyclic gear train.

33. The propulsion system according to claim 19, wherein the first motor is integral with the sun.

34. The propulsion system according to claim 19, wherein the crankset axle and the first input element are connected such that the first input element rotates faster than the crankset axle.

35. A pedal vehicle comprising a propulsion system according to claim 19, a frame, and a rear wheel.

36. The pedal vehicle according to claim 35, wherein the mechanical connection between the rear wheel and the powertrain passes through only one side of the rear wheel and comprises the propulsion system.

Description

BRIEF DESCRIPTION OF FIGURES

[0102] Further characteristics and advantages of the invention will become apparent from the following detailed description, for the understanding of which reference is made to the appended figures, among which:

[0103] FIG. 1 illustrates a three-dimensional view of a vehicle equipped with a propulsion system in which the transmission casing forms a self-supporting single-arm;

[0104] FIG. 2 illustrates a schematic section of a first variant of the first embodiment of the invention;

[0105] FIG. 3 illustrates a schematic section of a second variant of the first embodiment of the invention;

[0106] FIG. 4 illustrates very schematically an internal kinematic chain of a powertrain according to an embodiment of the invention;

[0107] FIG. 5 illustrates a side view of the transmission system integrated in a transmission casing according to an embodiment of the invention.

EMBODIMENTS OF THE INVENTION

[0108] The present invention is described with particular embodiments and references to figures but the invention is not limited thereby. The drawings or figures described are only schematic and are not limiting. In the context of this present document, the terms “first” and “second” are used only to differentiate the various elements and do not imply an order between these elements. In the figures, the identical or similar elements may have the same references.

[0109] FIG. 1 illustrates a three-dimensional view of a vehicle 79 equipped with a propulsion system according to an embodiment of the invention. The vehicle 79 comprises a frame 80, to which the propulsion system 1 is attached. The propulsion system 1 comprises a powertrain la and a first deformable transmission element 23 (shown in FIGS. 2 to 4) enclosed in a casing assembly 19. The casing assembly 19 preferably comprises a motor casing 19b and a transmission casing 19a (shown FIG. 5). In the illustrated embodiment, the transmission casing forms a single-arm. It is self-supporting and ensures the attachment of the rear wheel 72 to the frame 80. FIG. 1 also shows a crank 18, a brake disc 82 and a brake calliper 83

[0110] FIG. 2 illustrates a schematic cross-section of a first alternative of the first embodiment of the invention.

[0111] The powertrain la comprises a crankset axle 2 and a secondary output plate 4 with the same axis of rotation. This axis may be referred to as first axis of rotation 30. Preferably, the crankset axle 2 is attached to two cranks 18. Preferably, the powertrain la comprises a casing assembly 19, forming an envelope surrounding the first deformable transmission element 23 and the powertrain la, except for the ends of the crankset axle 2. The first deformable transmission element 23 provides torque transmission from the first 3 and/or the second output plate 4 to the rear wheel 24 sprocket.

[0112] The powertrain la comprises a main output plate 3 attached to the planet carrier 6, preferably at one end of the planet carrier 6, so as to rotate with the planet carrier 6.

[0113] The powertrain la also comprises a secondary output plate 4, attached to a hollow secondary output shaft 25 passing through the side wall of the casing assembly 19. The hollow secondary output shaft 25 is mounted on a bearing around the crankset axle 2. A first freewheel 16 is installed between the crankset axle 2 and the hollow secondary output shaft 25 so that the secondary output plate 4 cannot rotate slower than the crankset axle 2 when the crankset axle 2 is operated in the normal pedalling direction.

[0114] The powertrain la comprises a first motor 40 and a second motor 50. The first motor 40 comprises a stator 46 and a rotor 47 which preferably comprises magnets 48. The rotor 47 is arranged to rotate about a second axis of rotation 31. The torque of the rotor 47 is transmitted through the shaft 43 of the rotor to a sun 5. The second motor 50 comprises a stator 56 and a rotor 57 which preferably comprises magnets 58. The rotor 57 is arranged to rotate about a third axis of rotation 32. The torque from the rotor 57 is transmitted through the shaft 53 of the rotor to a third pulley 12.

[0115] A function of the first freewheel 16 is to allow a purely mechanical power transmission from the crankset axle 2 to the first deformable transmission element 23, even when the motors 40, 50 are not powered. In the locked position, the freewheel 16 makes the crankset axle 2 integral with the secondary output plate 4. In the free position, the output plate 4 is free to rotate faster than the crankset axle 2 when the crankset axle 2 is operated in the normal pedalling direction.

[0116] The powertrain la preferably comprises a current measuring element of the first motor 40 and a current measuring element of the second motor 50. The powertrain la further preferably comprises a control unit, preferably attached to a printed circuit board 20. The circuit board 20 is preferably located perpendicular to the second 31 and the third 32 axis of rotation.

[0117] Preferably, a first measuring magnet 42 is attached to an end of a shaft 43 of the first motor 40 and a second measuring magnet 52 is attached to an end of a shaft 53 of the second motor 50. Preferably, a first sensor 41 is attached to the printed circuit board 20, approximately in line with the second axis of rotation 31. The first sensor 41 and the first measuring magnet 42 are part of an angular position measuring element of the rotor 47 of the first motor 40. Preferably, a second sensor 51 is attached to the printed circuit board 20 approximately in line with the third axis of rotation 32. The second sensor 51 and the second measuring magnet 52 are part of an angular position measuring element of the rotor 57 of the second motor 50.

[0118] The control unit controls the first motor 40 and the second motor 50 on the basis of the angular position of the first motor 40, of the angular position of the second motor 50, of the current of the first motor 40 and of the current of the second motor 50, this information having been supplied to it by the measuring elements. The control unit controls the second motor 50 in current or in torque. The control unit controls the first motor 40 in angular position or in angular speed.

[0119] The powertrain la comprises an epicyclic gear train which comprises a first input element, an output element and the sun 5.

[0120] The powertrain la further comprises a second deformable transmission element 15, for example a chain or a belt, allowing to transmit a rotation between the crankset axle 2 and the first input element. This second deformable transmission element 15 forms a speed reduction system maintaining the direction of rotation.

[0121] In the first embodiment of the invention, which is that illustrated in FIGS. 2 and 3, the first input element is a ring gear 9 and the output element is a planet carrier 6. Preferably, the planet carrier 6 comprises at least one planet gear 8 arranged to rotate about a planet gear axle 7. Preferably, the ring gear 9 is meshed to at least one planet gear 8 via its internal toothing 10. Preferably, the sun 5 is meshed to the at least one planet gear 8.

[0122] In an embodiment of the invention, a first pulley 13 is integral with the crankset axle 2. The first pulley 13 is connected to a second pulley 14 by the second deformable transmission element 15. The second pulley 14 is integral with the ring gear 9. Preferably, the first pulley 13 has a larger diameter than the second pulley 14 in order to increase the speed of rotation relative to that of the crankset axle 2. For example, the diameter of the first pulley 13 may be between 1.5 and 3 times larger than that of the second pulley 14.

[0123] In the normal operating mode, the powertrain la according to the first embodiment of the invention operates as follows. The crankset axle 2 and the second motor 50 drive the ring gear 9, the drive between the crankset axle 2 and the ring gear 9 passing through the second deformable transmission element 15. The ring gear 9 is a first input of the epicyclic gear train. The first motor 40 drives the sun 5, which is a second input of the epicyclic gear train. The ring gear 9 and the sun 5 drive the planet carrier 6, which is an output of the epicyclic gear train. The planet carrier 6 drives the main output plate 3. The rotational speed of the main output plate will be equal to a weighted sum of the rotational speed of the ring gear 9 and of the rotational speed of the sun 5. By increasing the rotational speed of the sun 5, it is therefore possible to increase the speed of the main output plate 3, while keeping a constant rotational speed at the level of the crankset axle 2. It is therefore a continuously variable transmission (CVT).

[0124] The propulsion system 1 further comprises a third deformable transmission element 61, for example a chain or a belt, allowing to transmit a rotation between the third pulley 12, which is integral with the rotor 57 of the second motor 50, and an external toothing 11 of the ring gear 9. This third deformable transmission element 61 forms a speed reduction system maintaining the direction of rotation. The third pulley 12 has a smaller diameter than that of the ring gear 9, the aim being to reduce the speed of rotation in relation to that of the motor.

[0125] The sun 5 is integral with the rotor 47 of the first motor 40 so as to rotate with this rotor 47. The planet carrier 6 is integral with the main output plate 3.

[0126] The first deformable transmission element 23 is housed in the transmission casing 19a. The output power of the powertrain la is transmitted via the first deformable transmission element 23 to a rear sprocket 24. The rear sprocket 24 transmits the torque to a rear wheel axle 64 by means of a rear wheel freewheel 65. This freewheel 65 is positioned so that the rear sprocket 24 cannot rotate faster than the rear wheel 72 when the crankset axle 2 rotates in the normal pedalling direction. It is arranged to transmit the torque from the rear wheel sprocket to the rear wheel when the crankset is operated in its normal direction. The purpose of this freewheel 24 is to allow the cyclist to move forward without pedalling, for example when going downhill. A hub 67 of the rear wheel 72 is integrally attached to the rear wheel axle 64 by a nut 66. The hub 67 transmits the torque to the rear tire 71 via the spokes 68 and the rim 70.

[0127] The first freewheel 16 prevents the secondary output plate 4 from rotating slower than the crankset axle 2 when the crankset axle 2 rotates in the normal pedalling direction. The purpose of this freewheel 16 is that the gear ratio of the powertrain la cannot be less than 1:1.

[0128] FIG. 3 illustrates an alternative embodiment of the powertrain la in which a second freewheel 17 is installed between the crankset axle 2 and the first pulley 13. This freewheel 17 has the function of preventing the second motor 50 from driving the crankset axle 2 when the crankset axle 2 is operated in the normal pedalling direction.

[0129] The second freewheel 17 drives the first pulley 13 when the crankset axle 2 is operated in the normal pedalling direction, but the first pulley 13 cannot drive the crankset axle 2 when the crankset axle 2 is operated in the normal pedalling direction.

[0130] The embodiment shown in FIG. 3 illustrates a rear wheel assembly that does not contain a rear wheel freewheel 65. In this embodiment, the rear wheel sprocket 24 is integrally mounted to the rear wheel axle 64. In particular, this allows the powertrain la to be used to brake the vehicle 79. Indeed, the kinetic energy may be transmitted from the rear wheel 72 to the main output plate 3, so as to drive the first motor 40 and/or the second motor 50. The motor or the motors are thus driven in brake to recharge the battery. This motor brake can be activated, for example, by a manual control on the handlebar, or by back-pedalling. It is interesting to note that the driving of the rear wheel will not rotate the crankset during the motor brake, thanks to the presence of the second freewheel 17.

[0131] FIG. 4 illustrates very schematically an internal kinematic chain of a powertrain la according to an embodiment of the invention. According to this kinematic chain, the cyclist provides power to the input of the system via pedals 21, driving the crankset axle 2 via the cranks 18. The first pulley 13, which is integral with the crankset axle 2, drives via the second deformable transmission element 15, the ring gear 9, so that the latter rotates faster than the crankset axle 2. The third pulley 12, which is integral with the rotor 57 of the second motor (not shown in this simplified diagram), drives the external toothing 11 of the ring gear 9, via a third deformable transmission element 61, so that the latter rotates slower than the third pulley 12. The ring gear 9 is the first input of the epicyclic gear train. The sun 5, integral with the rotor 47 of the first motor (not shown in this simplified diagram), constitutes the second input of the epicyclic gear train. The sun 5 and the ring gear 9 are connected together via the planet carrier 6 comprising at least one planet gear 8. The planet gear or the planet gears 8 are held in a freely rotatable manner by axles 7 of the planet carrier 6. The planet carrier 6 is the output of the epicyclic gear train.

[0132] The arrows in FIG. 4 show the direction of rotation of the various members in normal operation of the powertrain la. In the interest of simplification and visibility of the diagram shown in FIG. 4, the various transmission members (wheel, sprocket, belt) appear smooth and may suggest a friction transmission. This does not, of course, preclude the use of toothings to make toothed wheels or serrated belts.

[0133] FIG. 5 illustrates a side view of the propulsion system 1 according to an embodiment of the invention. In this view, the cover of the transmission casing 19a has been deliberately hidden to reveal the internal transmission.

[0134] FIG. 5 illustrates a powertrain la, a first deformable transmission element 23, a rear wheel sprocket 24 and a tensioning roller 22. The first deformable transmission element 23 comprises an upper strand 23a, a lower strand 23b and an intermediate strand 23c. The intermediate strand 23c is the portion of the first deformable transmission element 23 located between the main output plate 3 and the secondary output plate 4.

[0135] The role of the tensioning roller 22 is to apply the right level of pre-tension in the first deformable transmission element 23, so that the latter is not too relaxed, once put under high load. The tensioning roller 22 may be fixedly mounted or mounted by means of a spring (not shown in FIG. 5) in order to take up the slack in the first deformable transmission element 23 when the transmission is loaded. It allows the intermediate strand 23c to remain tense. This tensioning roller 22 may be integrated into the casing assembly 19 of the powertrain 1a. It is placed so as to be in contact with the lower strand 23b. It is also possible to envisage a stationary operation without a tensioning roller 22.

[0136] In the normal operating mode of the powertrain la, the main output plate 3 drives the first deformable transmission element 23. The secondary output plate 4, being preferably meshed to the same first deformable transmission element 23 as the main output plate 3, rotates at no load at a higher speed than the crankset axle 2. The secondary output plate 4 is disengaged from the crankset axle 2 by means of the first freewheel 16.

[0137] In particular operating modes, different from the normal mode of operation of the powertrain la, the first freewheel 16 locks and prevents the secondary output plate 4 from rotating slower than the axle 2 of the crankset. In this case, the secondary output plate 4 drives, in whole or in part, the first deformable transmission element 23, and thus also the main output plate 3. If the electrical system is de-energized and/or if the assistance is deactivated and the lowest gear ratio of the powertrain la is selected (either by the user or by the control system), then all of the power of the cyclist is transmitted to the first deformable transmission element 23 via the secondary output plate 4. The rest of the transmission is therefore not loaded and the transmission is mechanically highly efficient.

[0138] Preferably, the main output plate 3 is smaller than the secondary output plate 4. Preferably, the rear sprocket 24 is smaller than the secondary output plate 4 and larger than the main output plate 3.

[0139] It is interesting to note that the arrangement of the powertrain la according to the invention is compatible with the powertrain variants described in the document WO2013/160477 or in the document WO2016/034574 or with other known powertrain variants.

[0140] In other words, the invention relates to a propulsion system 1 for a pedal vehicle. The propulsion system 1 comprises a powertrain la allowing to combine power from a crankset axle 2 and from two motors 40, 50, a first deformable transmission element 23 allowing to transmit power to the rear wheel 73 and a casing assembly 19 enclosing in particular the first deformable transmission element 23 and the powertrain la, with the exception of a portion of the crankset axle.

[0141] The present invention has been described above in relation with specific embodiments, which are purely illustrative and should not be considered limiting. In a general manner, the present invention is not limited to the examples illustrated and/or described above. The use of the verbs “comprise”, “include”, or any other variant, as well as their conjugations, can in no way exclude the presence of elements other than those mentioned. The use of the indefinite article “a”, “an”, or the definite article “the”, to introduce an element does not exclude the presence of a plurality of these elements. The reference numbers in the claims do not limit their scope.