Gearbox, powertrain for a vehicle including a gearbox, and vehicle including a gearbox

Abstract

The gearbox (29) includes an annular support (31) on which gear pairs (33A-33J) for inputting motion to the gearbox (29) are rotatably supported. Each of the gear pairs includes a first gear (35) adapted to receive the input motion and a second gear (37). The first gear (35) and the second gear (37) are coaxial and angularly coupled to each other for rotation as a unit. Each of the gear pairs defines a transmission ratio different from the transmission ratio defined by the other gear pairs. The annular support is angularly movable about a selected axis, whereby one of the gear pairs can be selectively placed in an angular motion disengagement position relative to the gearbox. The gearbox further includes a mechanical connection between a second gear of the gear pair in an angular motion disengagement position to the gearbox and an output shaft having an axis of rotation (AA) parallel to or coincident with the selected axis, where the output shaft passes through the annular support.

Description

[Technical Field]

[0001] The present invention relates to gearboxes, and more particularly to gearboxes for applications including, but not limited to, human-powered vehicles, such as pedal-assisted bicycles.

[0002] According to certain aspects, the present invention relates to vehicles such as various types of bicycles, bicycle taxis, tricycles, quadricycles, torpedoes, urban rickshaws, and tandem bicycles that include a propulsion-assist system, i.e., a drive assist. In this specification and the appended claims, the terms drive assist or propulsion assist are used synonymously unless otherwise stated. A propulsion-assist or drive-assist vehicle refers to a vehicle that can be propelled by the use of muscle power in combination with torque generated by a motor, such as, in particular, an electric motor. As described herein, a typical example of a drive-assist or propulsion-assist vehicle is a pedal-assist bicycle. [Background technology]

[0003] A known device for changing the gear ratio of a human-powered vehicle such as a bicycle includes multiple pinions coaxially mounted on the hub of a drive wheel, each pinion having a different diameter to define a different gear ratio. The device also includes a derailleur for disengaging the drive chain from one pinion and engaging another pinion to change gears, and a control (usually a manual cable control) for operating the derailleur.

[0004] In such a system, the various pinions are arranged in separate planes perpendicular to the hub of the drive wheel. Therefore, typically, a maximum of one pinion is arranged in the same plane as the crown. Therefore, the links of the drive chain are generally not arranged in the same plane, but at an angle to each other. The ideal operating condition for a drive chain is for the links to be aligned in the same plane. This arrangement results in high friction between the links. This results in a greater or lesser degree of deterioration in the transmission performance of the various gears, noise, increased wear, loss of lateral rigidity, the need for frequent maintenance, and impaired gearbox functionality.

[0005] Another drawback of transmission gearing is the inability to quickly and / or directly change between discontinuous gear ratios, which reduces vehicle performance, especially when road gradients change suddenly and significantly.

[0006] Furthermore, the transmission gearing does not allow the transmission ratio to be changed when the vehicle is stationary, nor does it allow the vehicle to tackle a hill with the appropriate transmission ratio already set.

[0007] To solve these problems, gearboxes have been developed, consisting of a box containing gears integrated into the hub of the drive wheel, typically the rear wheel hub, or into the central shaft. These gearboxes include multiple toothed wheels, each of which corresponds to a given gear ratio and is arranged along its own axis, thus having a particularly elongated shape along that axis. However, these gearboxes have various drawbacks.

[0008] Devices integrated into the drive wheel hub are not suitable for retrofitting; that is, they generally cannot be easily retrofitted to existing vehicles, especially those based on older technology, to modernize them. In fact, their installation requires the wheels to be replaced or modified to be suitable for assembly, which is extremely difficult for the user. Furthermore, since the gearbox-integrated hub replaces the regular hub and becomes part of the wheel, if the wheel is damaged, rapid recovery of the wheel and gearbox is only possible if the second wheel also has a gearbox, which significantly increases costs.

[0009] Furthermore, devices integrated into the drive wheel hubs reduce the dynamic balance of the vehicle by placing the entire weight on the rear wheels.

[0010] On the other hand, devices integrated into the central shaft require a specially shaped frame for installation, which limits the user's freedom of choice as they can only be replaced with identical devices, and for the same reason, these devices cannot be retrofitted.

[0011] Furthermore, devices integrated into the wheel hub and into the central shaft of the type described above make the introduction of a pedal-assist motor disadvantageous or impossible, particularly due to the axial size of the gear change device due to its arrangement along the axis of the toothed wheel corresponding to the various gear ratios.

[0012] In fact, known types of gearbox devices for installation on the hubs of the drive wheels completely occupy the space normally used for installing the motor, forcing the use of unconventional and expensive motors for installation on the central axle or on separate wheels (usually the front wheels). On the other hand, devices integrated on the central axle cannot be integrated with a coaxial motor, as the integrated device would be too long to be placed between the cranks. This requires that the motor be installed separately on the hubs of the drive wheels (typically the rear wheels), which also creates problems for the vehicle's weight distribution. This is even worse if the electric battery is installed above the drive wheels.

[0013] German Patent Application No. 740086 describes a vehicle gearbox having a central driven shaft to which multiple central driven gears with variable diameters are keyed. A drive shaft, coaxial with the driven shaft, transmits motion to the drive gears. Auxiliary shafts are arranged around the driven shaft. Each auxiliary shaft is keyed to a first toothed wheel adapted to mesh with the drive gear and a second toothed wheel adapted to mesh with one of the central gears. The number of driven shafts is equal to the number of central driven gears. One or the other of the auxiliary shafts is selected to transmit motion from the drive shaft to the driven shaft. Each auxiliary shaft's second pinion meshes with a different central driven gear, so that each auxiliary shaft provides a different gear ratio between the drive shaft and the central driven shaft. To bring the auxiliary shafts into an operating position corresponding to the desired transmission ratio, the auxiliary shafts are forced to move radially toward the drive shaft and the central driven shaft. To this end, each auxiliary shaft is supported by pads that are radially movable relative to the axes of the drive shaft and the central driven shaft, the radial movement being effected by translation of the support pads of the auxiliary shafts and controlled by cams mounted on rings that rotate about the axes of the drive shaft and the central driven shaft.

[0014] U.S. Patent Application No. 2019 / 0368579 (International Publication No. WO 2018095910) describes a gearbox particularly suited for bicycles. In some versions, the gearbox is integrated with an electric motor to form a pedal-assisted vehicle. While this device overcomes many of the shortcomings of prior art devices, it still has some limitations and room for improvement. In particular, the device described in this prior art publication, particularly in its pedal-assisted version, cannot be freely inserted into an existing vehicle, such as an existing bicycle, and requires the creation of an ad hoc frame. Summary of the Invention [Problem to be solved by the invention]

[0015] It would therefore be desirable to provide a gearbox with an integral motor that completely or partially overcomes the shortcomings of the prior art devices. [Means for solving the problem]

[0016] According to one aspect, described herein is a gearbox including an annular support on which gear pairs are rotatably supported for inputting motion into the gearbox. Each gear pair includes a first gear adapted to receive the input motion and a second gear. The first gear and second gear are coaxial and angularly coupled to one another for rotation in unison.

[0017] In fact, each of the gear pairs is rotatably supported on the annular support in the sense that it rotates about an axis common to the two coaxial gears, the axis being integral with the annular support, in other words, the annular support rotatably supports each gear pair.

[0018] Each gear pair defines a transmission ratio different from the transmission ratios defined by the other gear pairs. The annular support is angularly movable about a selected axis, thereby selectively positioning one gear pair in an angularly disengaged position relative to the gearbox. The gearbox further includes a mechanical connection between a second gear of the gear pair in an angularly disengaged position relative to the gearbox and an output shaft passing through the annular support and having an axis of rotation parallel to or coincident with the selected axis, i.e., the output shaft and the annular bearing are coaxial. In fact, the output shaft also extends within the annular support. Essentially, in the gearbox of the present invention, motion is introduced peripherally through one of the gears carried by the annular support, transmitted into the gearbox, and transmitted to the shaft passing through the annular support. To this end, advantageously, the first gear of each gear pair and the annular support are positioned such that the first gear in the angularly disengaged position receives input motion peripherally from a pinion of a drive member, the pinion being external to the annular support. In fact, in this way the input torque to the gearbox can be reduced, allowing for example the use of a lower torque motor, and also reducing the mechanical stress on the annular support which, together with each gear pair, constitutes the input member of the gearbox.

[0019] This can create a particularly compact and efficient drive system for some of the applications described herein, which can be easily retrofitted into existing vehicle frames if desired.

[0020] In a practical embodiment, the mechanical connection comprises a gear train, which may typically comprise a reduction gear.

[0021] In some embodiments, the mechanical connection includes a first ring gear meshing with a second gear of the gear pair in an angular disengagement position at the input to the gearbox. Preferably, the ring gear is a ring gear having a plurality of external teeth and has an axis of rotation passing through the annular support, for example, coincident with or parallel to a selected axis about which the annular support rotates.

[0022] The first ring gear may be part of a speed reducing gear train or a speed increasing gear train depending on the torque required at the output and the torque available by the source of motion that transfers motion to the gearbox.

[0023] If the mechanical connection includes a reduction unit, this may include a first ring gear and may have the form of a planetary gear mechanism. In a practical embodiment, the first ring gear constitutes the planet carrier of the planetary gear.

[0024] The possibility of using a reducer with a lower reduction ratio or (depending on the circumstances) a speed increaser is not excluded.

[0025] In an advantageous embodiment, the annular support and the first ring gear are coaxial or parallel and slightly spaced apart, such that the first ring gear can mesh with the second gear of each gear pair at any angular position of the annular support.

[0026] Further advantageous features and embodiments of the gearbox are described below with reference to the accompanying drawings and the appended claims.

[0027] According to yet a further aspect, the present subject matter includes a powertrain for a vehicle, including a motor having a drive shaft with a pinion, and a gearbox as described above and in more detail below. Advantageously, in the embodiments described herein, the pinion has an axis of rotation external to the annular support, whereby motion is input to the periphery of the gearbox via a first gear of the gear pair in a motion-disengagement position.

[0028] Advantageously, the annular support of the gearbox may be arranged so that rotation of the annular support about a selected axis selectively brings the first gear of one of the gear pairs into mesh with the pinion according to the required transmission ratio, the selective rotation being free in the sense that it is not limited to a single angle (360°).

[0029] Further advantageous features and embodiments of the powertrain are described below with reference to the accompanying drawings and the appended claims.

[0030] The present invention also relates to a vehicle including the powertrain described above.

[0031] In particular, the vehicle may be a traction-assisted vehicle, i.e. a propulsion-assisted vehicle, such as a pedal-assisted bicycle.

[0032] Specifically, according to some embodiments, the present invention relates to a vehicle including a frame, at least one drive wheel, at least one operating wheel, a motor including a drive shaft and a pinion rotated by the drive shaft, and a gearbox interposed between the motor and the drive wheel. The gearbox includes an annular support on which input gear pairs are rotatably supported. Each gear pair includes a first gear and a second gear that are coaxially coupled to each other angularly for integral rotation. Each gear pair defines a transmission ratio that is different from the transmission ratios defined by the other gear pairs. The annular support is angularly movable about a selection axis to selectively place one gear pair in an active position such that the first gear of the gear pair in the active position meshes with the pinion of the drive shaft. The vehicle further includes a mechanical connection between the second gear of the gear pair in the active position and an output shaft having an axis of rotation that passes through the annular support and is parallel to the selection axis. A device for rotating the annular support to effect shifting, i.e., changing the transmission ratio, may be provided. This allows the annular support to be selectively positioned at a plurality of angular positions. At each angular position, a respective gear pair is in an active position with the respective first gear meshing with the pinion of the drive shaft. The control device can be automatic, semi-automatic, servo-assisted, or fully manual. Preferred embodiments provide an automatic or semi-automatic gear change system.

[0033] Further features and embodiments of the vehicle are described below with reference to the accompanying drawings and appended claims.

[0034] The present invention also relates to a method for converting a human-powered vehicle, such as a bicycle, into a power-assisted or propulsion-assisted vehicle, comprising replacing the muscle power application mechanism to at least one drive wheel of the vehicle with a powertrain as described above and in more detail in various embodiments below.

[0035] As used herein and in the appended claims, a pedal-assist, traction-assist, or propulsion-assist vehicle generally refers to a vehicle having a motor, e.g., an electric motor, coupled via a suitable coupling mechanism with a mechanism that allows torque generated by the muscle power of a vehicle user or multiple vehicle users to be applied simultaneously to the drive wheel or wheels of the vehicle.

[0036] Torque can be generated by the user's lower or upper limbs, typically by rotating or swinging a pedal crank, lever, arm, handlebar, or other member to apply muscular force.

[0037] Thus, a vehicle with "pedal assist" or traction or propulsion assist, as understood herein, also includes vehicles in which muscle forces are generated by the user's upper limbs (arms) and not necessarily by their lower limbs (legs). [Brief explanation of the drawings]

[0038] The invention will become clearer from the following description and the accompanying drawings which show, by way of example, non-limiting embodiments of the invention. [Figure 1] 1 is a side view of a bicycle including a gearbox according to a first embodiment of the present invention integrated with a pedal-assist motor; FIG. [Figure 2] FIG. 2 is a plan view taken along line II-II in FIG. [Figure 3] FIG. 3 is a partial side view taken along line III-III in FIG. 2. [Figure 4] FIG. 6 is a cross-sectional view taken along line IV-IV in FIG. 5. [Figure 5] FIG. 5 is a cross-sectional view taken along line VV in FIG. [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI in FIG. [Figure 7] FIG. 1 is a functional block diagram of a control system for a vehicle having a shift and pedal assist system. [Figure 8]8 is a plan view similar to FIG. 2 of the second embodiment taken along line VIII-VIII in FIG. 2. FIG. [Figure 9] 9 is a cross-sectional view of the second embodiment taken along line IX-IX in FIG. 4, similar to the cross-sectional view of FIG. 5. [Figure 10] 7 is a cross-sectional view of the second embodiment taken along line XX in FIG. 4, similar to the cross-sectional view of FIG. 6. DETAILED DESCRIPTION OF THE INVENTION

[0039] The following describes a gearbox applied to a pedal-assisted bicycle. While this application is particularly advantageous, it should be noted that the gearbox described herein may have other applications. For example, the gearbox may be used in vehicles other than two-wheeled bicycles, such as tricycles or quadricycles, or in push-button vehicles. Furthermore, the gearbox may find advantageous application in vehicles that are driven solely by a motor associated with the gearbox, i.e., that do not have pedal cranks or other members for applying muscle power.

[0040] A first embodiment of a pedal-assist bicycle gearbox according to the present invention is shown in Figures 1-7. Figure 1 is a side view of bicycle 1, and Figure 2 is a top view thereof. Bicycle 1 includes a frame 3, a rear drive wheel 5, a front control wheel 7, and handlebars 9. In the illustrated example, bicycle 1 is a pedal-assist bicycle. Reference numeral 11 generally designates an actuation device, here referred to as a powertrain. The actuation device includes a motor, typically an electric motor 12, which is driven by a battery or storage unit 13 and controlled by a central control unit, also described below. Reference numeral 15 designates a pedal crank with respective pedals 16 for applying muscular force exerted by the user to powertrain 11. Drive unit 11 includes a toothed wheel for a chain, known as a chainring 19. A transmission chain 17 is threaded around this chainring 19. This transmission chain 17 transmits motion to a pinion 21 keyed to rear drive wheel 5.

[0041] The powertrain 11 also includes a gearbox between the electric motor 12 and the chain ring 19. The powertrain 11 further includes a mechanism that can combine the drive torque generated by the electric motor 12 with drive torque generated by muscle power applied via the pedal cranks 15. The gearbox and the drive torque combining mechanism will be described below with reference to Figures 3 to 7.

[0042] As shown particularly in Figures 3-6, the powertrain includes a housing generally designated by the reference numeral 23. This housing may be made up of several parts assembled together. Inside it are housed the motor 12, the gearbox, and the combination of the drive torque generated by the motor 12 and the pedal crank 15 with the opposing pedals 16. The housing 23 is integral with the frame 3.

[0043] In the embodiment shown, the housing 23 comprises a bushing 23A housed in a cylindrical part 3A of the frame 3. The bushing 23A forms the seat of the bottom bracket of the bicycle 1, i.e. the assembly including the pedal cranks 15, the pedals 16 and the shafts or pins joining the pedal cranks 15, as will be explained below.

[0044] The motor 12 has an output shaft 25 to which a pinion 27 is keyed. The pinion 27 may be secured to the shaft 25 by a keyway or other type of coupling. Alternatively, the pinion 27 may be formed integrally with the shaft 25. The line XX indicates the axis of rotation of the motor 12 and the relative shaft 25.

[0045] The pinion 27 transmits the torque, and thus the motion, generated by the motor 12 to the chainrings 19 via a gearbox, generally designated by the reference numeral 29. The gearbox 29 includes an annular support 31. The annular support 31 is supported in the housing 23 for rotation about an axis AA, which in the illustrated example coincides with the axis of rotation of the pedal crank 15 and constitutes a selection axis for selecting a transmission ratio, as will be described below. In the illustrated embodiment, the annular support 31 includes two rings that are integral with each other. A plurality of gear pairs 33 are rotatably supported on the annular support 31, more particularly between the two rings that form its main part. In the illustrated embodiment, the gearbox 29 has ten different transmission ratios, and therefore ten gear pairs, designated sequentially from 33A to 33J, are provided. Hereinafter, the reference numeral 33 will be used to designate a general gear pair.

[0046] Each of the gear pairs 33 includes a first gear 35 and a second gear 37 (see especially Figures 5 and 6). The two gears 35 and 37 of each gear pair are coaxial, integral with one another, and may be made as a single member. Each of the gear pairs 33 is supported in a floating manner on the annular support 31. In this way, each of the gear pairs 33 is rotatably supported on the annular support 31. As shown in the figures, each of the gear pairs 33 actually has a shaft and is associated with a support bearing for rotatably supporting the gear pair on the annular support 31. The shaft of each of the gear pairs 33 is stationary relative to the annular support 31.

[0047] The first gears 35 of all gear pairs 33 are coplanar with one another. Similarly, the second gears 37 of all gear pairs 33 are coplanar with one another. More specifically, the first gears 35 are arranged in a plane perpendicular to the rotational axis AA of the annular support 31 so that each first gear 35 can selectively mesh with a pinion 27 keyed to the shaft 25 of the motor 12. In the position shown in FIG. 4 , the first gear 35 of gear pair 33A meshes with the pinion 27. By rotating the annular support 31 about the axis AA, the first gear 35 of any one of the gear pairs 33 can be selectively meshed with the pinion 27.

[0048] The plane on which the second gears 37 are disposed is arranged so that the second gears 37 mesh with a first ring gear 41 that rotates about an axis AA. In the illustrated embodiment, the positions of the annular support 31, gear pairs 33, and first ring gear 41 are such that the second gears 37 of all gear pairs 33A-33J simultaneously mesh with the first ring gear 41, as shown particularly in FIG.

[0049] The first ring gear 41 is supported by bearings 43 for free rotation about axis AA. The latter is disposed between the first ring gear 41 and a hollow shaft 45 which, as will be described below, constitutes the output shaft of the gearbox 29 and powertrain 11. The output shaft 45 rotates about axis AA and, together with the chainring 19, transmits motion to the chain 17. The first ring gear 41 constitutes an element of a planetary gear set, generally designated by the reference numeral 47. This receives motion from the pinion 27 via one of the gear pairs 33A-33J and transmits this motion to the chainring 19 via the output shaft 45 at an appropriate reduction ratio. The axis AA constitutes the axis of the planetary gear set about which the components rotate, as will be described below.

[0050] The first ring gear 41 forms the planet carrier of the planetary gear set 47. Two planetary units 51 are supported in a floating manner on the planet carrier consisting of the first ring gear 41. The number of planetary units 51 may differ from that shown in the figures. In a simplified embodiment, a single planetary unit 51 is sufficient. The use of two or more planetary units allows for a better distribution of the forces involved.

[0051] Each planetary unit 51 includes a first toothed wheel 53 and a second toothed wheel 55 (see FIG. 5). The two toothed wheels 53 and 55 of each planetary unit 51 are coaxial and angularly aligned with each other so that they rotate together around their respective axes. Each planetary unit 51 is supported by a bearing 71 on a planet carrier formed by the first ring gear 41 so as to be free to move. The first toothed wheel 53 of each planetary unit 51 meshes with a second ring gear 59 that is coaxial with the first ring gear 41. The second ring gear 59 forms the sun gear of the planetary gear mechanism 47 and is fixed to the housing 23 and, therefore, the frame 3 of the bicycle 1. A bearing 60 is disposed coaxially with the second ring gear 59 and forms a radial bearing for the hollow output shaft 45.

[0052] Therefore, when the first ring gear 41 constituting the planet carrier of the planetary gear mechanism 47 rotates around the axis AA, the axis of the planetary unit 51 rotates around the axis AA, and the first toothed wheel 53 of the planetary unit 51 rolls on the second ring gear 59.

[0053] Each second toothed wheel 55 of the planetary unit 51 meshes with a third ring gear 61 that is coaxial with the first ring gear 41 and the second ring gear 59. The third ring gear 61 constitutes the sun gear of the planetary gear set 47 and is coaxial with the axis AA. While the second ring gear 59 is fixed relative to the housing 23, the third ring gear 61 is supported rotatably about the axis AA.

[0054] Generally, the third ring gear 61 is mechanically connected to the hollow output shaft 45 and transmits thereto the rotational motion generated by the motor 12. In some embodiments (not shown), the third ring gear 61 may be keyed to the output shaft 45. In contrast, in the illustrated embodiment, the mechanical connection between the third ring gear 61 and the output shaft is achieved through the interposition of a freewheel 62 (see FIGS. 5 and 6) for purposes described below.

[0055] As the planet carrier formed by the first ring gear 41 rotates about the axis AA of the planetary gear set 47, the second toothed wheel 55 transmits the rotational motion to the third ring gear 61 with a reduction defined by the planetary gear set 47 and the third ring gear 61. This motion is transmitted via the hollow output shaft 45 to the gearbox 19 and from there via the chain 17 to the rear drive wheels 5.

[0056] In general, the vehicle 1 may be an electric motor vehicle that moves by power supplied from the motor 12. In this case, the freewheel 62 may be replaced by a fixed torsional connection between the output shaft 54 ​​and the third ring gear 61. Also, the output shaft 45 may be solid rather than hollow.

[0057] On the other hand, in the illustrated embodiment, the vehicle 1 is a pedal-assisted bicycle in which forward motion is also achieved by the user's muscular power via the pedal cranks 15 and pedals 16. The two pedal cranks 15 are fixed to the ends 63A of a pin 63, the axis of which coincides with the rotation axis AA of the planetary gear mechanism 47 and the annular support 31. The pin 63 constitutes a transmission shaft for the drive torque generated by muscular power, which can be used in addition to or instead of the drive torque transmitted by the drive shaft 25 to propel the vehicle 1 forward, and is therefore referred to as the auxiliary shaft hereinafter. The auxiliary shaft or journal 63 is rotatably supported within the bushing 23A by a bearing 65. The auxiliary shaft passes through the hollow output shaft 45 and is supported therein by bearings 67, such as needle roller bearings. In this way, the auxiliary shaft 63 and the output shaft 45 can rotate relative to each other about the common axis AA.

[0058] However, the auxiliary shaft 63 and the hollow output shaft 45 are connected to each other by a second freewheel 69 so that under certain conditions the hollow shaft 45 can rotate freely around the auxiliary shaft 63 and under other conditions the auxiliary shaft 63 can rotate the hollow output shaft 45.

[0059] The assembly including the motor 12, gearbox 29, bottom bracket with auxiliary shaft 63, and pedal crank 15 with pedals 16 operates as follows: The desired gear ratio can be set manually or automatically by rotating the annular support 31 and selecting the gear pairs 33 required to achieve that ratio. The drive torque generated by the motor 12 is transmitted to the gearbox 19 and from there to the rear drive wheel 5 via preselected gear pairs 35, 37. These gears 35, 37 are in their angularly disengaged, or active, position, with their respective first gears 35 meshing with the pinions 27. The torque is transmitted via the second gear 37 to the first ring gear 41 (which constitutes the planet carrier of the planetary gear train 47) and from there to the third ring gear 61 via toothed wheels 53, 55. When the auxiliary shaft 63 is stationary or rotating at an angular velocity lower than that of the third toothed wheel 61, the motion is transmitted by the auxiliary shaft 63 via the first freewheel 62 to the output shaft 45 and thus to the gearbox 19.

[0060] The second freewheel 69 allows the output shaft 45 to rotate relative to the auxiliary shaft 63 and exceed it at an angular velocity.

[0061] When the user, by means of the pedal crank 15 and pedals 16, rotates the auxiliary shaft 63 at an angular velocity greater than the angular velocity of the third ring gear 61, the auxiliary shaft 63 is torsionally coupled to the output shaft 45 by the second freewheel 69, causing the two shafts 63, 45 to rotate together, while the first freewheel 62 torsionally releases the auxiliary output shaft 45 from the third ring gear 61, allowing the shaft 45 to rotate faster than the third ring gear 61.

[0062] The transmission ratio between the electric motor 12 and the output shaft 45 can be changed by rotating the annular support 31 in stages and positioning one of the multiple gear pairs 33A to 33J supported freely on the annular support 31 in an active position, i.e., a motion disengagement position (the position where gear pair 33A is positioned in the figure).

[0063] The powertrain 11 described above can be easily integrated into newly built bicycles or used as a retrofit to upgrade existing bicycles. In fact, the entire component set (motor, gearbox including planetary gear mechanism) can be accommodated in a standard existing bicycle frame without modification. The seat 3A, which is typically provided in the frame 3 to accommodate a conventional bicycle bottom bracket, can accommodate the bushing 23A of the seat 23 without modification.

[0064] Thus, the powertrain 11 can be used to convert a conventional bicycle into a pedal-assisted bicycle, with an automatic or manual gear change system. In particular, as will be described below, the powertrain 11 can be provided with a control unit and appropriate sensors, via which the control unit can control the gearbox and set the drive mode to appropriately manage the power flow.

[0065] Rotation of the annular support 31 to set the desired transmission ratio can be performed manually using a suitable mechanism for transferring movement from a lever or control knob located on the handlebars to the annular support 31. However, in a preferred embodiment, to facilitate the operation of changing the transmission ratio, and possibly automatically by a control unit, the gearbox includes a device for rotating the annular support 31, generally designated by the reference numeral 71. This rotation device can be as described in U.S. Patent Application No. 2019 / 0368579 (WO 2018095910), the entire contents of which are incorporated herein by reference.

[0066] In the illustrated embodiment, the rotation device 71 includes an actuator, such as an electric motor 73. This rotates a shaft 75, on which a shaft 80 integral with the molded disk 77 is keyed about axis YY. The latter cooperates with the annular support 31 via a pin 79 and two crescent-shaped or semicircular cams 81. The pin 79 is adapted to fit into a radial groove 83 in the annular support 31, and the semicircular portions 81 are adapted to cooperate with complementary recesses 31A provided on the rings forming the annular support 31. The annular support 31 has, on its two rings, a number of recesses 31A equal to the number of gear pairs 33A-33J and a number of radial grooves 83 equal to the number of gear pairs 33A-33J. Each rotation of the molded disk 77 rotates the annular support 31 of the gearbox 29 by one pitch. Thus, the gear pairs 33 are displaced at their meshing positions with the pinions 27 by the adjacent gear pairs. An absolute encoder 85, mechanically connected to the shaft 75 via a gear chain 87 having the appropriate transmission ratio, stores the angular position of the disk 77 and thus of the annular support 31, even in the event of a power failure. In this way, the central control unit 89 always has information about which transmission ratio is engaged, i.e. which of the various gear pairs 33 are in the active position meshing with the pinion 27.

[0067] As the gear changing operation requires a complete rotation of the disc 77 about the axis YY, in some embodiments a sensor 91 is provided, for example a Hall sensor cooperating with a magnet 93 integral with the disc 77. Via this sensor the central control unit 89 can verify that the gear changing operation has been completed.

[0068] 7 shows a schematic representation of the sensors and central control unit 89 for managing the vehicle 1. The figure shows an absolute encoder 85 for identifying the engaged gear, a sensor 91, the gear-changing actuator 73, a force sensor 95 for detecting the force applied by the user to the pedal crank 15, an angular velocity sensor 97 for detecting the angular velocity of the auxiliary shaft 63 and the pedal crank 15, a speed sensor 99 for detecting the speed of the vehicle 1, and the electrical energy store 13.

[0069] Components may be located on the handlebars 9 including a monitor or display 101, a button set or other interface 103 for setting the vehicle advancement system management mode, and a second interface 105 for setting the transmission ratio in a non-automatic manner if desired.

[0070] The arrangement of electrical and electronic components described above allows for a series of management methods of the electric motor 12 and the gearbox 29. Management of the performance and type of operation of the powertrain 11 may be performed by a central control unit 89 which constitutes the central node of the connection network between the various electrical devices described above as shown in Figure 7. It should be noted that performance may be managed through various command and control modes, some examples of which are given below, but are not limited to:

[0071] According to a possible manual control method, the transmission ratio is manually selected by acting on the gearbox 29, with the possibility of freely selecting any available transmission ratio. The set transmission ratio is detected by the absolute encoder 85 and displayed on the display 101. This manual control can be associated with the possibility of manually selecting from several constant performance levels of the motor 12. These performance levels can also be displayed on the display 101. In this type of manual control of the motor 12 and the gearbox 29, the energy input to the device via the auxiliary shaft 63 is added to the energy input from the electric motor 12. Together, they contribute to determining the forward speed of the vehicle 1 until the maximum permissible speed is reached. This is achieved by using a constant torque selected by the user and generated by the motor 12. The power supply to the motor 12 is gradually reduced and finally cut off when the vehicle reaches the maximum permissible speed detected by the speed sensor 99.

[0072] According to another semi-automatic management method, the gearbox 29 can be operated automatically. This can be combined with manual selection of a constant torque level provided by the electric motor 12, with the possibility to select from several motor performance levels displayed on the display 101. In this semi-automatic command and control mode, the automatic management of the gearbox 29 relies on the results of an algorithm that tends to reach the maximum permissible speed of the vehicle 1 within the range allowed by the drive torque limit set by the user for the electric motor 12, and processes data flowing to the central control unit 89, in particular the rotational speed of the electric motor 12, the speed of the vehicle 1, and the current absorption of the electric motor 12. For this purpose, the electric motor 12 can be associated with various sensors, in particular a speed sensor, interfaced with the central control unit 89.

[0073] In some embodiments, the electric motor 12 may be a brushless motor. In some embodiments, the motor 12 may already be provided with all the necessary sensors, in particular a speed sensor. In Figure 7, the motor speed sensor is not shown, but is integrated into the motor itself, i.e., forms an integral part of the motor 12 instrumentation.

[0074] A further semi-automatic management method can provide the opposite case to that described above, i.e. automatic management of the level of torque supplied by the electric motor 12 and manual control of the gearbox 29, in the same automated application as described above.

[0075] According to yet another automatic management mode, automatic control of the gearbox 29 and the electric motor 12 can be provided via algorithms running on the central control unit 89. This can, for example, be advantageous for saving electrical energy. In this fully automated command and control mode, specific algorithms process the data flowing to the central control unit 89 via the aforementioned sensors and return information useful for commanding the gearbox and controlling the electric motor 12. Here, a compensation management mode of mechanical energy is provided to the device via two different input paths: the pedal 16 and the motor 12. This mode complements the energy value supplied to the device via the auxiliary shaft 63 and pedal crank 15 with the energy value introduced via the electric motor 12, giving priority to the energy from the auxiliary shaft, and always keeping the sum of the two energies equal to the total energy supplied to the device, set by the user via the desired energy level selected on a predetermined scale.

[0076] The energy, and therefore the power, of the motor 12 has a maximum value allowed by the standard or the equipment manufacturer, and the motor management operates within this value, with further limits set via the operating mode set by the user, as described above.

[0077] That is, in a manual or semi-automatic management method, the user or central control unit applies a constant torque level to the motor 12 and the maximum allowable power limit that may be reached is controlled by the central control unit 89, while in a fully automatic mode the performance of the motor 12 varies between zero and the maximum possible or allowable value, in both torque and power, depending on the performance level selected by the user and the muscle torque applied.

[0078] In this last fully automatic mode, a larger amount of energy from the pedal crank 15 corresponds to a smaller amount of energy from the electric motor 12, up to the limit condition of the energy being introduced entirely via pedal actuation.

[0079] In addition to balancing the energy sources described above, the fully autonomous management mode pursues the goal of maximizing vehicle autonomy through the selection of gear ratios, which are appropriately selected to keep the motor 12 in a rotational regime close to maximum efficiency and minimum energy consumption.

[0080] As mentioned above, in the automatic command and control mode, data is required regarding the energy input via the auxiliary shaft 63. For this purpose, a force sensor 95 is provided which detects the force acting on the auxiliary shaft 63 via the pedal crank 15. The output data from the force sensor 95, together with the value of the rotational speed of the auxiliary shaft 63 detected by the speed sensor 97, make it possible to calculate the value of the energy supplied by the muscle force path.

[0081] A further embodiment of a gearbox according to the invention is shown in Figures 8, 9 and 10. Figures 4 and 7 show parts that are the same in the further embodiment. Like reference numerals indicate parts that are the same or equivalent to parts described with reference to Figures 1 to 7 and these will not be described in detail again.

[0082] The embodiment of Figures 8-10 differs from the embodiment of Figures 1-7 primarily in the way in which the muscle forces generated by the user via the pedal crank 15 and pedals 16 are introduced into the powertrain.

[0083] In the embodiment of Figures 8 to 10, the auxiliary shaft 63 is supported within the hollow output shaft 45 and bushing 23A by bearings 65 and 67, but is not connected by a second freewheel 69. Furthermore, the third ring gear 61 is keyed directly to the hollow output shaft 45 and rotates integrally therewith, regardless of the rotational speed of the motor 12 and pedal crank 15. Indeed, for example, in the embodiment of Figures 8 to 10, the third ring gear 61 is formed integrally with the hollow output shaft 45.

[0084] The transmission of torque generated by the muscular force exerted by the user via the pedal crank 15 is via the motor 12. Indeed, in this embodiment, a first freewheel / bearing 162 is keyed to the drive shaft 25 and is interposed between the drive shaft 25 and the rotor 12R of the electric motor 12. Reference numeral 12S schematically denotes the stator of the electric motor 12. A second freewheel / bearing 169 is keyed to the shaft 25 and is interposed between the drive shaft 25 and an auxiliary gear 171 that is coaxial with the drive shaft 25. The auxiliary gear 171 meshes with an auxiliary ring gear 173 that is keyed to the auxiliary shaft or pin 63 that receives the motion from the pedal crank 15. The auxiliary ring gear 173 is housed in a protective casing 175.

[0085] The above-described components combine the motion of the pedal crank 15 and the auxiliary pin or shaft 63 with the motion imparted by the motor 12 in the following way: When the pedal crank 15 rotates due to thrust applied by the user's muscles, the auxiliary shaft 63 rotates about axis AA. This rotation is transmitted to the freewheel / bearing 169 via the auxiliary ring gear 173 and the auxiliary gear 171. This allows the auxiliary gear 171 to transmit motion to the drive shaft 25 when the angular velocity imparted to the auxiliary gear 171 is greater than the angular velocity of the rotor 12R of the motor 12. In this condition, torque is transmitted to the pinion 27 via the second freewheel / bearing 169 and the shaft 25, and the first freewheel / bearing 162 releases the rotation of the rotor 12R.

[0086] On the other hand, if the angular velocity of the rotor 12R of the motor 12 is higher than the angular velocity applied to the auxiliary gear 171 by the pedal crank 15, the second freewheel / bearing 169 angularly decouples the auxiliary gear 171 from the drive shaft 25 and the first freewheel / bearing 162 transmits torque from the rotor 12R to the drive shaft 25 and from there to the pinion 27.

[0087] 8-10 operates similarly to the embodiment shown in Figures 1-7 when the angular velocity of the motor 12 exceeds the angular velocity of the auxiliary gear 171. Also, when the velocity applied by the user via the pedal crank 15 is such that the angular velocity of the auxiliary gear 171 exceeds the angular velocity of the motor, muscle force no longer passes directly from the pin or auxiliary axle 63 to the hollow shaft output gear 45, but rather passes through the kinetic chain of the auxiliary ring gear 173, auxiliary gear 171, drive shaft 25, pinion 27, and gearbox 29 to the output shaft 45 and thence to the chainring 19.

[0088] From the viewpoint of mechanical efficiency, the embodiment shown in Figures 8 to 10 is disadvantageous compared to the embodiment shown in Figures 1 to 7. This is because part of the muscle force is dissipated in the kinetic chain described above, from the pin or auxiliary shaft 63 through the drive shaft 25 and the gearbox 29 having the relative reducer consisting of the planetary gear mechanism 47 to the output shaft 45. On the other hand, the embodiment shown in Figures 8 to 10 has the advantage that the user can change the gear ratio by using the gearbox 29, even when using the vehicle 1 by pedal operation alone, without using the power of the motor 12.

[0089] In both of the above-described embodiments, the annular support 31 with the gear pairs that constitute the moving elements for changing the transmission ratio is located upstream of the reducer rather than downstream, and therefore at a low torque, unlike other transmissions in similar applications, which reduces the stresses on the moving components of the transmission.

[0090] The device provided with the electric motor 12 can be used as an OEM vehicle component or as a retrofit upgrade for vehicles that already have or do not have a conventional gearbox arrangement with multiple chainrings and pinions. Indeed, the device described herein can be configured to be mounted on a standard frame and replace other possible components for transmitting motion to the wheels. This allows these vehicles to be converted into pedal-assisted vehicles, or more generally, into propulsion-assisted or traction-assisted vehicles.

[0091] Unlike conventional gearboxes, the device described herein does not require adjustments during installation on the vehicle or during use, and therefore does not require special skills from the installer, particularly the user.

[0092] Maintenance requirements are very limited to regular checking of the oil level in the gearbox (but no oil is consumed) and cleaning and lubricating the chain 17.

[0093] In some embodiments, the chain 17 may be advantageously replaced by a toothed belt or other continuous flexible member, which may further reduce vehicle maintenance. The possibility of transmitting motion to the shaft transmission member using a suitable transmission joint is not excluded.

[0094] By maximizing the attributes of duration and reliability, the system is suitable for use in vehicles with intensive use that require functional safety of the entire motion transmission. Consider, for example, vehicles such as bicycle taxis, tricycles, quadricycles, torpedoes, urban rickshaws, cargo bikes, etc. These vehicles require high reliability and do not allow easy access to repair or intervene in the mechanical transmission during use if, for example, the chain simply comes off, as occurs in conventional transmission systems.

[0095] Furthermore, because the chain 17 always runs in alignment, i.e., with the drive wheel pinion and the chainring 19 always in the same plane, it is not subject to the premature wear problems typical of systems with variable speed gears. The chain 17 can therefore be wider than chains traditionally used in vehicles with variable speed gears, which further extends the operating period and minimizes the need for interventions to replace worn parts.

[0096] As a result, the chain drive (chain ring 19, chain 17, sprocket 21) typically wears out over a much longer period of time. Furthermore, this wear on the transmission does not affect the proper functioning of gear changes, as occurs in conventional derailleur systems.

[0097] The system described herein has a minimal weight due to the presence of the gearbox, and in particular the use of a small electric motor, yet there is sufficient power generated at relatively low speeds, which has a further beneficial effect on the complexity, weight and performance of the gearbox / reducer system.

[0098] A further advantage is that by locating the motor 12 below the bottom bracket of the vehicle (i.e., below axis AA), the center of gravity of the entire vehicle is lowered, thereby significantly improving the dynamic characteristics and handling of the vehicle 1.

[0099] In order to maximize the dynamic characteristics of the vehicle, it is advantageous to locate the central control unit 89, and in particular the battery 13, below the diagonal tube 3B (FIG. 1) of the frame 3, so that the center of gravity is located at the lowest possible height.

[0100] The gearbox and relative reducer assembly is particularly advantageous, but not exclusively, when used for propelling bicycles or other saddle-mounted vehicles. The gearbox and the respective reducer can be used particularly advantageously in traction-assisted or propulsion-assisted vehicles, since the advantageous embodiment described above allows for easy integration of the gearbox and reducer system in vehicles equipped with a pedal crank bottom bracket for muscle traction. However, the possibility of using a gearbox with a relative reducer for other applications is not excluded. Here, a combination of motion provided by a primary power source, such as the motor 12 transmitting motion to the gear pair 33, and motion provided by an auxiliary power source via the auxiliary shaft 63 can be envisaged.

Claims

1. A gearbox (29), (a) an annular support (31) on which gear pairs (33A-33J) for inputting motion to the gearbox (29) are rotatably and guideably supported, the shafts of each of the gear pairs are stationary relative to the annular support; each of said gear pairs (33A-33J) includes a first gear (35) adapted to receive an input motion and a second gear (37), said first gear (35) and said second gear (37) being coaxial and angularly coupled to one another so as to rotate together; each of said gear pairs (33A-33J) defines a gear ratio different from the gear ratios defined by the other gear pairs; the annular support (31) is angularly movable about a selected axis to selectively position one of the gear pairs (33A-33J) in angular disengagement relative to the gearbox (29); An annular support (31); (b) a mechanical connection between the second gear (37) of the gear pair (33A-33J) in the angularly disengaged position relative to the gearbox (29) and an output shaft (45) having an axis of rotation (A-A) parallel to or coinciding with the selected axis, the output shaft (45) passing through the annular support (31), the mechanical connection including a reducer (47) or an increaser, the reducer (47) or the increaser including a first ring gear (41) meshing with at least the second gear (37) of the gear pair (33A-33J) in the angularly disengaged position relative to the gearbox (29); a gearbox (29) including:

2. 2. The gearbox (29) of claim 1, wherein the first gear (35) of the gear pair (33A-33J) and the annular support (31) are positioned such that the first gear (35) of the gear pair (33A-33J) in the angular motion disengagement position receives input motion peripherally from a pinion (27) of a drive member (12), the pinion (27) being external to the annular support (31).

3. 2. The gearbox (29) of claim 1, wherein the annular support is adapted to rotate about the selected axis without angular restriction.

4. A gearbox (29) as described in claim 2, wherein the annular support is adapted to rotate about the selected axis without any restriction on the rotation angle.

5. 2. The gearbox (29) of claim 1, wherein the first ring gear (41) has external teeth and a rotation axis passing through the annular support (31), the rotation axis being parallel to or coincident with the selection axis.

6. A gearbox (29) as described in claim 2, 3, or 4, wherein the first ring gear (41) has external teeth and a rotation axis passing through the annular support (31), the rotation axis being parallel to or coincident with the selected axis.

7. 2. The gearbox (29) according to claim 1, wherein the annular support (31) and the first ring gear (41) have parallel axes or the same axis, and the first ring gear (41) meshes with the second gear (37) of each of the gear pairs (33A to 33J) at any angular position of the annular support (31).

8. A gearbox (29) as described in claim 2, 3, or 4, wherein the annular support (31) and the first ring gear (41) have parallel axes or the same axis, and the first ring gear (41) meshes with the second gear (37) of each of the gear pairs (33A to 33J) at any angular position of the annular support (31).

9. The gearbox (29) according to any one of claims 1 to 5 and 7, wherein the reducer (47) includes a planetary gear mechanism, the first ring gear (41) constituting a planet carrier of the planetary gear mechanism (47), the planet carrier rotating about a central axis of the planetary gear mechanism (47) coinciding with the axis of the output shaft (45), and at least one planet section (51) including first and second toothed wheels supported so as to be freely movable on the planet carrier and coaxially connected angularly to each other.

10. 10. The gearbox (29) of claim 9, wherein the first toothed wheel (53) of the planetary unit (51) meshes with a second ring gear (5) coaxial with the first ring gear (41) that is fixed relative to a bearing structure, and the second toothed wheel (55) of the planetary unit (51) meshes with a third ring gear (61) rotatable about the axis of the output shaft (45), and a mechanical coupling is arranged to transmit motion from the third ring gear (61) to the output shaft (45).

11. 8. The gearbox (29) of any one of claims 1 to 5 and 7, further comprising a device (71) for rotating the annular support (31), the device (71) being adapted to selectively position the annular support (31) in a plurality of angular positions, at each of which one of the gear pairs is in the angular motion disengagement position relative to the gearbox (29).

12. 11. The gearbox (29) of claim 10, wherein the mechanical coupling between the third ring gear (61) and the output shaft (45) includes a first freewheel (62).

13. 13. A gearbox (29) according to claim 12, wherein the output shaft (45) is a hollow shaft, an auxiliary shaft (63) for inputting motion from an auxiliary motion source extends coaxially with the output shaft (45), and a second freewheel (69) is arranged between the hollow output shaft (45) and the auxiliary shaft (63).

14. A powertrain (11) for a vehicle, comprising: a motor (12) having a drive shaft (25) with a pinion (27); A gearbox (29) according to any one of claims 1 to 5 and 7; Including, the annular support (31) of the gearbox (29) is arranged so that rotation of the annular support (31) about a selected axis selectively brings the pinion (27) into mesh with a first gear (35) of one of the gear pairs (33A-33J) according to the required transmission ratio, the pinion having an axis of rotation outside the annular support (31), whereby motion is input to the periphery of the gearbox via the first gear (35) of the gear pair (33A-33J) in an angular disengaged position relative to the gearbox; Powertrain (11).

15. A powertrain (11) as described in claim 14, wherein the motor (12) is an electric motor including a stator (12S) and a rotor (12R), a first freewheel (162) is interposed between the rotor (12R) and the drive shaft (25), and a second freewheel (169) is interposed between the drive shaft (25) and an auxiliary gear (171) coaxial with the drive shaft (25) and adapted to receive torque from an auxiliary power source, and is keyed to the drive shaft (25).

16. 16. The powertrain (11) of claim 15, wherein the auxiliary gear (171) meshes with an auxiliary ring gear (173) keyed to the auxiliary shaft (63).

17. A powertrain (11) as described in claim 16, wherein the auxiliary shaft (63) is coaxial with the axis of the output shaft.

18. A powertrain (11) as described in claim 16, wherein the auxiliary shaft is rotatably supported within the output shaft (45).

19. A powertrain (11) as described in claim 16, wherein members (15, 16) for applying muscular force to the auxiliary shaft (63) are keyed at both end portions of the auxiliary shaft (63).

20. A vehicle (1), Frame (3), At least one drive wheel (5); At least one operating wheel (7); a motor (12) including a drive shaft (25) and a pinion (27) rotated by said drive shaft; a gearbox (29) interposed between the motor (25) and the drive wheels (5); Including, The gearbox is configured as described in any one of claims 1 to 5 and 7, wherein the pinion (27) of the drive shaft (25) is arranged outside an annular support (31) of the gearbox, and the annular support (31) is adapted to be arranged in a plurality of angular positions, whereby in each of the angular positions, the gear pairs (33A to 33J) are in an active position with the first gear (35) of each of the gear pairs (33A to 33J) disengaged from the pinion (27) of the drive shaft. Vehicle (1).

21. 21. A vehicle (1) according to claim 20, wherein the vehicle is a power-assisted vehicle and includes an auxiliary shaft (63) to which a member (15, 16) for applying muscular force to the auxiliary shaft (63) is keyed, the auxiliary shaft being connected to an output shaft (45) via a system including a freewheel.

22. The motor (12) is an electric motor including a stator (12S) and a rotor (12R), The system including the freewheel comprises: a first freewheel (162) interposed between the rotor (12R) and the drive shaft (25); a second freewheel (169) keyed to the drive shaft (25), interposed between the drive shaft (25) and an auxiliary gear (171) coaxial with the drive shaft (25), and meshing with an auxiliary toothed wheel (173) keyed to the auxiliary shaft (63); Including, The auxiliary shaft (63) is coaxial with the axis of the output shaft (45) and is rotatably supported within the output shaft (45).

22. A vehicle (1) according to claim 21.

23. 21. A vehicle (1) according to claim 20, wherein the output shaft (45) is a hollow shaft, an auxiliary shaft (63) for inputting motion from an auxiliary motion source extends coaxially with the output shaft (45), and a second freewheel (69) is arranged between the hollow output shaft (45) and the auxiliary shaft (63).

24. 21. The vehicle (1) according to claim 20, wherein the vehicle is a bicycle including a bottom bracket, and the output shaft (45) is coaxial with the bottom bracket.

25. 20. A method for converting a human-powered vehicle (1) into a power-assisted vehicle, comprising the step of inserting a powertrain according to claim 17 into the torque transmission line of the drive wheels (5) of said vehicle (1).

26. 26. The method of claim 25, wherein the vehicle (1) is a bicycle and the powertrain is used in place of a bottom bracket of the bicycle.

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