Gearshift device and associated mobility vehicle

Description

[0001] The field of the present invention is that of so-called soft mobility, and more particularly that of mobility devices combining electric propulsion and muscular force, namely electric-assisted bicycles.

[0002] When riding a bicycle, the driving force is provided by the cyclist, it is transmitted to the wheels via a crank system rotating around a bottom bracket axle which drives the rear wheel usually by a chain.

[0003] Gearboxes for bicycles are known from the prior art. In particular, publication FR2975367 A1 discloses a bicycle gear-changing device comprising a geared gearbox and a sliding shuttle for gear selection. The axial movement of the shuttle is controlled by two cables connected to a rotating handlebar grip. This system requires numerous parts. Its manufacture and maintenance are complex. In particular, the cable control requires precise and regular adjustments. There is a need to simplify and automate bicycle gearboxes.

[0004] As the field of light pedal-powered vehicles for transporting goods or people diversifies, there is also a need for automatic and electric gearboxes.

[0005] To meet at least some of these needs, the invention, according to a first aspect, relates to a gear-changing device for a mobility device of the electric-assist bicycle type, said device having a plurality of ratios between a first ratio, referred to as ratio no. 1, and a higher ratio, referred to as ratio k, said gear-changing device comprising a series of k input gears arranged to rotate freely around a selection shaft, said selection shaft housing a worm gear and a shuttle; a series of k output gears, rotationally fixed to a hollow shaft, said hollow shaft being arranged to surround a crank axle of the mobility device; a gear-changing actuator arranged to move the shuttle along the worm gear between a plurality of k positions and engage a selected ratio.

[0006] Each of the reports presents a particular ratio between the output speed and the input speed of the gear change device.

[0007] The number of positions of the shuttle is at least equal to the number of gears of the gear-changing device.

[0008] Each ratio corresponds to a particular position of the shuttle in which the input pinion of the selected ratio meshes with the corresponding output pinion.

[0009] As soon as the user pedals, the hollow shaft rotates, driving the shuttle. Thanks to the invention, during a gear change, the worm gear is rotated by the gear-shifting actuator. The rotational movement of the worm gear is transformed into a translational movement of the shuttle, which moves to the position corresponding to the selected gear ratio.

[0010] The hollow tree is here a selection axis; the two expressions are used equivalently in this application.

[0011] The invention thus proposes a compact, space-saving gear-changing device.

[0012] The worm gear driven by the speed change actuator eliminates the cables of the previous art and thus provides a more reliable, easy-maintenance solution.

[0013] The gear-shifting actuator includes mechanical means for translating the shuttle, in particular means for transforming a rotational motion into a translational motion. The gear-shifting actuator also includes electrical means for moving the shuttle, in particular a geared motor. Advantageously, the gear-shifting device according to the invention has, alone or in combination, one or more of the following characteristics: The shuttle is arranged so that, in each position corresponding to a gear ratio, it engages an associated input gear to mesh with the output gear associated with that gear ratio. The shuttle houses at least one return element, specifically arranged to cooperate with at least one ball on the selector shaft. Thanks to this ball-spring mechanism, the shuttle can engage an input gear to mesh with the associated output gear. The shuttle can house one or more return elements, for example, between one and six return elements. For each gear ratio, the return element(s) cooperate with one or more balls on the selector shaft, for example, between one and six balls.For a given gear ratio, the number of balls on the selector shaft is less than or equal to the number of return elements on the shuttle. The shuttle surrounds the worm gear. The gear-shifting device has between 2 and 12 ratios, or even between 5 and 9 ratios. The gear-shifting device includes a pivot joint. The gear-shifting actuator comprises a motor and a gearbox and / or an epicyclic gear train. The gearbox, in particular, comprises a plurality of gears positioned between the motor and the worm gear. In this application, the term geared motor is used to designate, depending on the embodiment, the motor, the gearbox, and / or the epicyclic gear train. The gear-shifting actuator is arranged to move the shuttle between predefined positions following a gear selection command from a mobility device operator and / or a mobility device control unit.The shuttle is capable of assuming a so-called neutral position in which no gear is engaged. In other words, the shuttle is in a position where it is not engaged with any input gear; the input and output gear pairs are not meshing. Specifically, when the shuttle is in the neutral position, meaning the gear-shifting mechanism is in a neutral gear, the movement of the pedals does not propel the bicycle. The shuttle is also capable of assuming a reverse gear position which, when engaged, allows the mobility device to be propelled backward while pedaling forward.

[0014] In a first embodiment, the changing device comprises a rail along which the shuttle moves. The rail is housed within the selector shaft. The shuttle may have at least one axial channel along its entire length in which the rail is positioned. The channel, or one of the channels, thus serves to hold the rail in place.

[0015] When the gear ratio is not changed, the worm gear does not turn.

[0016] During a speed change, the worm gear is driven into rotation by the speed change actuator.

[0017] The shuttle is connected to the rail by a nut. The rail provides linear support, preventing the nut from rotating. The axial movement of the nut drives the shuttle, thus enabling gear changes.

[0018] The nut is specifically housed inside the shuttle.

[0019] The rail and nut are thus part of the mechanical means of translation of the shuttle. They form a pivot joint between the worm gear and the shuttle, transforming the rotational movement of the worm gear into the translational movement of the shuttle.

[0020] According to a second embodiment, the gear-changing device includes at least one epicyclic gear train. This replaces the rail and nut of the previous embodiment. The epicyclic gear train is part of the mechanical means for translating the shuttle. In particular, the epicyclic gear train is a double epicyclic reduction gear comprising an inner ring gear fixed to the selector shaft and an outer ring gear fixed to the worm gear. The two ring gears, inner and outer, are linked by at least three planetary gears.

[0021] Under steady operating conditions, a gear is engaged, and the shuttle is in the position corresponding to that gear, allowing the corresponding input and output gears to mesh. The worm gear, the selector shaft, and the shuttle rotate at the same speed. To change gears, the geared motor temporarily rotates the outer ring gear by a specific angle, which depends on the necessary movement of the shuttle between the positions corresponding to the initial and desired gear ratios. Due to the resulting angular shift between the inner and outer ring gears, the ratio between the rotations of each ring gear is temporarily no longer equal to one. The shuttle is thus moved in translation until it reaches a new position corresponding to the newly selected gear ratio.

[0022] According to an unclaimed aspect, the present application also relates to a transmission assembly for a mobility device, said transmission assembly comprising an electric motor, in particular arranged to provide all or part of the energy for the propulsion of the device, and a gear-changing device as described above.

[0023] According to another aspect, the invention relates to a mobility device of the type electrically assisted bicycle comprising a gear-changing device, as described previously

[0024] The device may include a rechargeable power source, in particular a battery to power the geared motor. This battery is preferably arranged to power the various components of the mobility device, in particular the lighting, an optional location / navigation system, etc. (this list is not exhaustive).

[0025] In one particular embodiment, the mobility device includes an electric motor, equipped, for example, with a gearbox. The mobility device is specifically arranged so that the electric motor can provide torque when the instantaneous speed of the mobility device is below a threshold value.

[0026] In another unclaimed example, the mobility device is without electric assistance.

[0027] According to an unclaimed aspect, the present application also relates to a method for controlling a gear-changing device, as described above.

[0028] The process includes, in particular, a step of engaging a selected gear of the gear-changing device. During this step, a control unit commands the gear-changing actuator based on a user input indicating the chosen gear. Brief description of the figures

[0029] Other features, details and advantages of the invention will become clearer upon reading the description given below by way of example in conjunction with drawings in which: There [ Figure 1 ] is a view of a mobility device according to one aspect of the invention, the [ Figure 2 ] illustrates the entire transmission system of the mobility device of the Figure 1 , the figures [ Fig. 3a], [Fig. 3b] et [Fig. 3c ] present cross-sectional views of a gear-changing device according to a first embodiment of the invention, the [ Figure 4 ] illustrates a housing containing a gear-changing device according to the invention, the figures [ Figure 5] et [Figure 6 ] illustrate in cross-section a gear-changing device according to a second embodiment of the invention, the figures [ Fig. 7a] à [Fig. 7g ] schematically represent different variants of a gear-change actuator according to the first embodiment of the invention, and the figures [Fig. 8a] à [Fig. 8g] schematically represent different variants of a speed change actuator according to the second embodiment of the invention. Detailed description of the invention

[0030] There Figure 1 This illustrates a mobility device 900 according to one aspect of the invention. The device 900 is an electrically assisted bicycle comprising an electric motor 300 with an axis of rotation X m. Said electric motor is arranged to provide part of the propulsion of said device.

[0031] When moving without electric assistance, the driving force is provided by the cyclist, it is transmitted to the 950 wheels via two pedals rotating around an Xp bottom bracket axle which drives the rear wheel by a chain.

[0032] As shown by Figure 1 The 900 device includes a control unit 800 as well as several sensors 80, located in particular at the level of the pedal assembly, on the frame of the bicycle or at the level of a wheel.

[0033] The device 900 shown here also includes an energy storage device in the form of a battery 910, a lighting system 920, a pedal assembly 940 with an Xp axle, a localization and / or navigation system 980, and a human-machine interface system 990 comprising, in particular, a touchscreen capable of displaying information and / or responding to user requests. The human-machine interface system 990 is specifically linked to the localization system 980 and serves as the navigation interface. The invention is not limited to a particular human-machine interface system and may include any system known to those skilled in the art.

[0034] The 950 wheels are equipped with a 960 braking system, including 965 disc brakes.

[0035] The 900 engine includes a 700 transmission assembly as illustrated Figure 2 The transmission assembly 700 includes a speed changing device 100 according to the invention and an electric motor 300 with axis of rotation Xm to provide part of the power for the propulsion of the machine 900.

[0036] The transmission assembly 700 is at least partially housed in a casing 600 (illustrated) figure 4 ) here positioned at the level of the 940 pedal assembly whose axis coincides with the X 3 output axis of the 100 gear change device.

[0037] The gear change is automatic and electric.

[0038] The illustrated 100 speed change device figures 3a and following presents a plurality of 7 ratios between a first ratio called ratio no. 1 and a higher ratio called ratio 7,

[0039] It comprises a series of 7 output pinions 30 of axis X 3, of reference F 1 to F 7, fixed in rotation to a hollow shaft and a series of 7 input pinions 20, of reference Fr 1 to Fr 7 arranged to rotate freely around a selection shaft 200. The latter houses a shuttle 155 surrounding a worm gear 132 of the speed change device 100. A speed change actuator 150 is arranged to move the shuttle 155 along the worm gear 132 between 7 positions from P 1 to P 7 and engage a selected ratio.

[0040] The device is compact, the 200 selection shaft is hollow

[0041] The speed change actuator 150 includes electrical means for moving the shuttle, in the form of a geared motor. This comprises a motor 140 and a gearbox 130. The speed change actuator 150 also includes mechanical means for translating the shuttle 155, in particular means for transforming a rotational motion into a translational motion.

[0042] The geared motor assembly here includes a pinion 135 on the shaft of the worm gear 132, an intermediate pinion 135 and a pinion 135 on the Xm shaft of the motor 140. The teeth of the pinion 135 can be straight as illustrated or helical in a variant not illustrated.

[0043] As shown by figure 3a , the gear change is ensured by a shuttle 155 sliding under the free gears 30 of the gearbox.

[0044] The speed change actuator 150 allows axial movement of the shuttle along a worm gear 132 by a helical kinematic link.

[0045] The shuttle 155 therefore stops under the input pinion Fri corresponding to the selected ratio i. A spring / ball system as described in French patent application FR2975367 A1 (illustrated here in more detail) is used. figure 5 This allows the input sprocket Fri to be locked in rotation. Once engaged, the input sprocket Fri meshes and transmits the forces to the output sprocket Fi and thus to the chain sprocket linked to the bicycle wheel.

[0046] The rotational guidance of the worm gear 132 is, for example, ensured by means of bearings at each of its ends. Figure 3a This illustrates, in particular, a needle bearing on the pinion side 135 of the reducer 130 and a ball bearing at the other end of the worm gear 132. figures 3b et 3c represent detailed views of the gear-changing device of the figure 3a ,

[0047] While shuttle 155 is illustrated on the figure 3a in position P 7 corresponding to a ratio n°7, here a higher ratio, and that it engages the input pinion Fr 7 so that it meshes with the output pinion F 7, on the figure 3b The shuttle 155 is in position P1, corresponding to gear ratio #1, and engages the input pinion Fr1 via a ball-spring mechanism. The shuttle houses a return element 152 which cooperates with a ball 151 on the selector shaft 200.

[0048] The shuttle 155 is also connected to a rail 134 by a nut 138.

[0049] If the 900 unit is running in a gear i, without changing it, the worm gear 132 does not turn. As shown by the figure 3c , the shuttle 155 surrounding the nut 138 can rotate thanks to the bearing 136 here held by a clip 137.

[0050] During a gear change, the worm gear 132 is driven in rotation by the gear shift actuator 150. The worm gear 134 is driven in rotation by the gear shift actuator 150, causing axial movement of the nut 138, which drives the shuttle 155 and thus enables the gear change. Thanks to the pivot joint thus created, the rotational movement of the worm gear 132 is transformed into a translational movement of the shuttle 155. A stop 133 at each end limits the movement of the shuttle 155. The stops 133 are, for example, hollow as illustrated and house bearings 136 used to support and guide the worm gear 132.

[0051] In an unrepresented variant, the shuttle 155 is capable of taking a position called neutral position P0 for which no speed ratio is engaged.

[0052] In the example of a gear-changing device described above, the gear-changing actuator 150 has spur gears. In the context of this invention, the geared motor may have helical gears.

[0053] There Figure 4 illustrates in more detail the 600 case of the 900 mobility device of the figure 1 .

[0054] The housing 600 comprises a casing 660 that defines a first compartment 610 designed to house the gears of the speed-changing device 100. The casing 660 also defines several secondary compartments, distinct from one another. Compartments 640, 630, 615, and 680 are designed to house, respectively, the electric motor 400, the gearbox 300, the speed-changing actuator 150, and the control unit 800 of the mobility device. The secondary compartments are preferably sealed, particularly the one designed to house the control unit 800.

[0055] The 660 housing containing the 100 gear-changing device is closed by two side flanges 667. The 600 housing is shown empty and with only one flange 667 on the Figure 4 to make the different first and second housings more visible. The first housing 610 has two opposite holes in the side flanges 667 to accommodate the bottom bracket axle of the mobility device 900.

[0056] THE Figures 5 et 6 relate to the second embodiment. The speed change device 100 comprises an epicyclic train 130' having an inner ring 30 int fixed to the selection shaft 200 and an outer ring 30 ext fixed to the worm gear 132. The inner ring 30 int and the outer ring 30 ext are linked by three planetary gears 135.

[0057] Under steady running conditions, the worm gear 132, the selector shaft 200, and the shuttle 155 rotate at the same speed. To change the gear ratio, the geared motor 140 temporarily rotates the outer ring gear by a predetermined angle that depends on the necessary displacement of the shuttle 155 between the positions corresponding to the initial and desired gear ratios, respectively. Due to the resulting angular shift between the inner ring gear 30int and the outer ring gear 30ext, the ratio between the rotation of each ring gear is temporarily no longer equal to one. The shuttle 155 is thus driven in translation until it reaches a new position corresponding to the newly selected gear ratio.

[0058] The first embodiment with rail and nut is not limited to a type of geared motor with parallel axis gears as illustrated figure 3a The axes of the geared motor's pinions can be perpendicular.

[0059] Whereas in the illustrated variants of the first embodiment, in particular the illustrated example figure 3a The geared motor has several 135 pinions, the figure 7a corresponds to an example where the 130 reducer is limited to a single pinion.

[0060] There figure 7b illustrates a variant in which the gear shift actuator 150 has a bevel gear 130 b.

[0061] There figure 7c illustrates a variant in which the gear change actuator 150 has a spur or helical gear with one or more stages 130 c.

[0062] There figure 7d illustrates a variant in which the gear change actuator 150 has a spur or helical gear without a stage 130 d.

[0063] There figure 7e illustrates a worm gear 130 e of a variant of a speed change actuator 150.

[0064] THE figures 7f et 7g represent respectively variants comprising a 150 gear change actuator with a 130 f belt, respectively a 130 g chain.

[0065] Similarly, the figures 8a à 8g schematically represent different variants of a speed change actuator according to the second embodiment of the invention.

[0066] There figure 8a corresponds to the example illustrated in figure 5a with the epicyclic train 130'.

[0067] There figure 8b illustrates a variant in which the gear change actuator 150 b has an epicyclic gear train 130' and bevel gear.

[0068] There figure 8c illustrates a variant in which the 150c gear-shifting actuator has a 130' epicyclic gear train and spur or helical gear with one or more stages. figure 8d illustrates a variant in which the 150 d gear-shift actuator has a 130' epicyclic gear train and a spur or helical gear without a stage. figure 8e illustrates a variant in which the 150 e gear-shift actuator has a 130' epicyclic gear train and worm gear. figures 8f et 8g represent respectively variants comprising a 150 f gear change actuator with 130' epicyclic gear and belt, respectively 150 g with 130' epicyclic gear and chain.

Claims

1. Gearshift device (100) for an electric-assist bicycle (900), said device having a plurality of k gear ratios between a first ratio called ratio No. 1 and a higher ratio called ratio k, said gearshift device comprising - a series of k input sprockets (20, Fr1 to Frk) arranged to rotate freely around a selection shaft (200) of axis X2, said selection shaft housing a worm screw (132) and a shuttle (155), - a series of k output sprockets (30, F1 to Fk) of axis X3, rotationally integral with a hollow shaft (230) arranged to surround a bottom bracket axle of the electric-assist bicycle (900), and a gearshift actuator (150) arranged to move the shuttle (155) along the worm screw (132) between a plurality of k positions (P1 to Pk) and engage a selected gear ratio.

2. Gearshift device according to claim 1, the shuttle (155) being arranged to, in each position (Pi) corresponding to a gear ratio (i), engage one of the input sprockets (Fri) so that it meshes with the corresponding output sprocket (Fri), the input sprocket (Fri) and output sprocket (Fi) being associated with said gear ratio (i).

3. Gearshift device according to claim 1 or 2, the shuttle (155) being arranged to house at least one return member (152).

4. Gearshift device according to any one of the preceding claims wherein the shuttle (155) surrounds the worm screw (132).

5. Gearshift device according to any one of the preceding claims comprising a pivot connection.

6. Gearshift device according to any one of the preceding claims wherein the gearshift actuator (150) comprises a motor (140), and a reduction gear (130) or an epicyclic gear train (130').

7. Gearshift device according to any one of the preceding claims wherein the gearshift actuator (150) is arranged to move the shuttle (155) between the predefined positions (Pi, P1 to Pk) following a gear selection command from a rider of the mobility vehicle and / or a control unit (800) of the mobility vehicle.

8. Gearshift device according to any one of the preceding claims wherein the shuttle (155) is capable of assuming a position called the neutral position (PO) for which no gear ratio is engaged.

9. Gearshift device according to any one of claims 1 to 8 comprising a rail (134) along which the shuttle (155) moves, said rail being located in particular within the selection shaft (200).

10. Gearshift device according to any one of claims 1 to 8 comprising an epicyclic gear train (130') with an inner ring gear (30int) and an outer ring gear (901ext).

11. Electric-assist bicycle comprising a gearshift device (100) according to any one of the preceding claims.