Electric powertrain for bicycle and its piloting mode.

Abstract

Electric bicycle drive unit: mounted on the bottom bracket, connected to the rear wheel by an independent track parallel to the bottom bracket, and without a freewheel, allowing the motor to be driven by the rear wheel and operate as a generator; Between its two reduction stages, the first by gears and the second by roller chain or toothed belt, it features a clutch, disengagement, and parking lock mechanism; Controlled by a computer that defines the assistance and regenerative braking levels, clutch engagement, disengagement, and locking based on information from: speed sensors, battery charge level, requested assistance level, braking level, incline, ignition key presence and activation, and the position of the sliding sleeve control fork. Figure for the abbreviation: Fig. 1

Description

Title of the invention: Electric powertrain for bicycle and its control method. TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to an electric powertrain for a road-use bicycle.

[0002] The powertrain is arranged at the level of the pedal assembly and has a dedicated transmission to the rear wheel, with two reduction stages, independent of that of the pedal assembly.

[0003] It is a transmission without a freewheel, which makes it possible for the rear wheel to drive the motor which then switches to electric braking mode, i.e. generator and therefore recovers energy.

[0004] The first reduction stage of this transmission is a pair of pinions contained in a sealed volume and is lubricated.

[0005] The second reduction stage of this transmission is a pair of open-air gears linked by a chain or a toothed belt.

[0006] Between the driven pinion of the first reduction stage and the driving wheel of the second reduction stage is arranged in the sealed and lubricated volume, a dog clutch device allowing the connection / disconnection of the motor as well as locking the bicycle in parking. STATE OF THE ART

[0007] There are many different ways to provide electric assistance for a bicycle. The motor can be located in the hub of the rear wheel, the front wheel, or even in each wheel hub.

[0008] The motor, arranged at the level of the pedal assembly, can transmit its power to the rear wheel in a common manner with the pedal assembly, a very common situation, or by a dedicated transmission in parallel with that of the pedal assembly.

[0009] On mopeds with internal combustion engines, the two transmissions were, for the most part, independent.

[0010] This solution is also known for electrically assisted bicycles. Publications FR3067698 and FR3082180 can be cited in particular.

[0011] Energy recovery is present on all electric cars during braking and sometimes as soon as the accelerator pedal is released. This is a virtually non-existent function on electric bicycles. In publication EP2921396A2, the assistance motor is arranged at the bottom bracket and the transmission is shared with the bottom bracket. The sprockets of the rear wheel drive the rear wheel via a wheel Freewheeling. For energy recovery, the freewheel is neutralized by a parallel clutch. The pedals are then driven by the wheel, which is not a comfortable situation. PRESENTATION OF THE INVENTION

[0012] The bicycle is equipped with an electric powertrain consisting of a direct current or alternating current motor, synchronous or asynchronous, and a reduction gear the first stage of which consists of a driving pinion and a driven pinion, with helical or straight teeth, arranged in a sealed compartment containing a liquid lubricant, and the second stage of which consists of a driving toothed wheel arranged in the axis of the crankset, but independent of it, and a driven wheel arranged in the axis of the rear wheel, and linked by a roller chain or a toothed belt.

[0013] The gearbox housing has, in its lower part, a drain plug in which is inserted a magnet for retaining ferrous filings.

[0014] The cover of the gearbox housing closure has a filler plug arranged in the area above the crankshaft.

[0015] A hollow shaft, mounted on a needle bearing, partially surrounds the crankshaft, carries the fixed driving sprocket of the second stage, guides the driven sprocket of the first stage mounted on a smooth ring, carries a fixed hub and a sliding grooved sleeve allowing the coupling-decoupling of the driven sprocket to the hollow shaft and thus of the electric motor to the rear wheel.

[0016] The driven pinion of the second stage is of the fixed type with respect to the axis of the rear wheel, which allows a flow of power from the wheel to the electric motor which then operates as a generator.

[0017] The sliding connection sleeve of the motor has axial notches on one of its sides.

[0018] The three-position sliding sleeve for connecting the electric motor: • In the first one, it is entirely supported by the driven pinion: the electric motor is disconnected; • In the central position, it is supported by both the driven pinion and the fixed hub: the motor is connected to the rear wheel with a possible power transmission in both directions; • In a third position, still supported by the driven pinion and the fixed hub, the axial teeth are engaged in a fixed toothing belonging to the engine casing.

[0019] This third position creates a lock of the motor, the rear wheel and indirectly of the pedal assembly and acts as an anti-theft device.

[0020] The sleeve is controlled by a fork whose sliding axis carries an arm equipped with a threaded hole cooperating with the threaded axis of a stepper motor for control.

[0021] The locking-unlocking device is controlled by a computer and responds to the presence of an activation ignition key.

[0022] The bicycle is equipped with a crankset fitted with a dedicated chainring independent of the electric transmission.

[0023] The chainring drives, via a chain, a single or multiple sprocket carried by the axle of the rear wheel and driving the latter, due to the presence of a freewheel, only in forward motion.

[0024] Between the bottom bracket shaft and the housing of the electric drive unit is interposed a second freewheel preventing backpedaling.

[0025] The combined actions of the two freewheels on the rear wheel sprocket on the one hand and on the bottom bracket axle on the other hand prevent the bicycle from rolling backwards and provide comfort when restarting uphill because it eliminates the need for the braking devices.

[0026] The electric assistance device acts according to the terrain by receiving information from the slope sensor. DETAILED DESCRIPTION OF THE INVENTION

[0027] These features, objectives and advantages of the present invention will become apparent from the detailed description that follows and from the accompanying drawings given by way of non-limiting examples and on which:

[0028] Fig. 1 is a first cross-sectional view of the powertrain passing through the electric motor shaft, the crankshaft shaft and the filler and drain plugs.

[0029] Fig. 2 is a second cross-sectional view of the powertrain passing through the electric motor shaft, the crankshaft shaft and the rotation speed sensors, the crankshaft shaft (pedaling speed) and the hollow shaft, i.e., bicycle speed.

[0030] Fig. 3 is a third cross-sectional view of the powertrain passing through the electric motor shaft, the crankshaft, the fork shaft, and the sliding sleeve control motor shaft. The sliding sleeve is in the disengaged position.

[0031] Fig. 4 is a fourth cross-sectional view of the powertrain passing through the engine shaft, the crankshaft, the fork shaft, and the sliding sleeve control motor shaft. The sliding sleeve is in the dog clutch position.

[0032] Fig. 5 is a fifth cross-sectional view of the powertrain passing through the electric motor shaft, the crankshaft, the fork shaft, and the sliding sleeve control motor shaft. The sliding sleeve is in the locked position.

[0033] Fig. 6 is a flowchart of the information entering and leaving the computer.

[0034] Fig. 1 shows the powertrain 10 in a cross-section through the shaft of the assist motor 20, the crankshaft 50, the filler cap 60 and the drain cap 61.

[0035] The motor 20, in the embodiment presented, is of the permanent magnet synchronous type, is arranged in a motor housing 21, and is composed of a wound stator 22, a rotor 23 carried by a shaft 24.

[0036] The speed control of the motor 20 is achieved using the resolver 27 (speed and angular position sensor of the rotor shaft 24), arranged in the motor housing 21.

[0037] The rotor shaft 24 is supported by the permanently lubricated and sealed ball bearings 25.

[0038] The engine compartment is closed by the housing 31 of the reduction gear 30 carrying one of the two bearings 25.

[0039] At the end of the rotor shaft 24 is cut the teeth 24a which constitute the driving pinion of the reducer 30.

[0040] Between the electric motor 20 and the rear wheel (not shown) the mechanical linkage has two levels of reduction. The first is a reducer 30 consisting of a driving gear 24a and a driven pinion 34.

[0041] It is arranged in an enclosed space 30a consisting of a motor housing 21, a gearbox housing 31 and its cover 32.

[0042] This closed space 30a is sealed against the internal space of the motor 20 by a dynamic seal 26 and against the outside by dynamic seals 40,42,59 and static seals 58,85 (see [Fig.3]).

[0043] This closed space 30a contains a liquid lubricant introduced through a filling plug 60 and discharged through a drain plug 61 which carries a cylindrical magnet 62 for retaining the iron filings released during use.

[0044] The driving gear 24a and the driven pinion 34 have, on their outer periphery, straight or helical teeth. The reduction ratio is on the order of 13.

[0045] In the bearing of the driven pinion 34 is fitted a smooth ring 35. It is carried by a hollow shaft 36 with which it occasionally has a differential speed of rotation.

[0046] The hollow shaft 36 is supported by the shaft 50 of the crankset. Between these two shafts 36 and 50, which have permanently different rotational speeds, is interposed a needle bearing 37.

[0047] The hollow shaft 36 is axially blocked with play, on the left, by a shoulder 50a, and on the right, by a spacer 55 of the crankset.

[0048] The hollow shaft 36 carries on its outer profile in the enclosed space 30a, in addition to the driven pinion 34, a dog clutch hub 38, driven in rotation by splines 36a and stopped by a ring, a target 70 for a bicycle speed sensor (see also [Fig.2]), a guide ball bearing 41 in the cover 32 also stopped by a ring, and finally serves as a bearing for the dynamic seal 42.

[0049] The hollow shaft 36, has on its inner profile to seal the closed space 30a, a dynamic seal 40.

[0050] The hollow shaft 36, on its grooved end 36b, outside the closed space 30a, carries a toothed wheel 43 (also stopped by a ring), driving the second stage of linkage of the electric motor 20 with the rear wheel (not shown).

[0051] The driven pinion 34, on the outer area of ​​its bearing 34a which extends laterally beyond the teeth, carries splines 34a 1. The hub 38 carries on its outer periphery splines 38al identical to those of the pinion. On these splines 34al, 38al a sleeve 39 slides axially to engage (dog clutch situation) or disengage (disengagement situation) the driven pinion 34 from the hub 38.

[0052] The spacer 55 carried by the shaft 50 of the crankset is fixed to the latter in rotation by means of the splines 55b and 50b.

[0053] Externally, it carries notches 55a which form the reading track of the crankset rotation sensor (see also [Fig. 2]), and a guide bearing 56 in the motor housing 21. It serves as tracks for the rollers of a freewheel 57 and the dynamic joint 59.

[0054] The freewheel 57 prevents the crankshaft 50 from rotating in the opposite direction to forward motion (prevents backpedaling). Its action, combined with that of the freewheel associated with the rear wheel sprocket(s) (not shown), prevents the bicycle from rolling backward and thus provides comfort when maintaining stability on inclines and restarting, as it eliminates the need for the braking devices associated with each wheel (not shown).

[0055] The bottom bracket shaft 50 has, at each of its ends, splines 50b for driving two arms 51 and 52, positioned 180 degrees apart, at the ends of which pedals (not shown) are arranged, and a conical zone 50c for axially positioning the two arms. They are axially locked by screws 53 on the conical zones 50c.

[0056] The force and speed of pedaling are transmitted to the rear wheel by a toothed sprocket 54, arranged laterally to the drive unit 10 on the opposite side to the toothed wheel 43. The toothed sprocket 54 is dedicated to the pedaling of the cyclist and the toothed wheel 43 to the assistance motor 20.

[0057] Fig. 2 shows the drive unit 10 according to a section passing through the shaft of the assist motor 20, the gear pair and pinion 24a, 34, the crankshaft 50, a speed sensor 71 giving the speed of the bicycle and a speed sensor 72 giving the pedaling speed.

[0058] The speed sensor 71 arranged on the cover 32, has as its reading track notches 70a cut into a target 70. This target carried by the hollow shaft 36 in permanent connection with the rear wheel (not shown) by means of a driving toothed wheel 43.

[0059] The speed sensor 72 arranged on the motor housing 21 of the motor 20, has as its reading track notches 55a cut in the spacer 55, in permanent connection with the crankshaft 50 via the splines 55b and 50b.

[0060] The bicycle speed sensor 71 communicates information that is interpreted by a computer (not shown). This information is essential for the computer to control the motor 20 at the near-synchronization speed of the driven sprocket 34 with the hub 38, allowing for rapid and quiet engagement.

[0061] Fig. 3 shows the drive unit 10 according to a cross-section passing through the shaft of the assist motor 20, the gear pair and pinion 24a, 34 of the reducer 30, the shaft 50 of the crankset, an axis 83 of a fork 82 for moving the sliding sleeve 39 and the shaft of the stepper motor 81 of the actuator 80.

[0062] The shaft 83 of the fork 82 passes through the engine casing 21. Sealing is achieved by the quasi-static seal 85.

[0063] On the outer part of the shaft 83, an arm 84 with a threaded hole 84a through which a threaded shaft 81a passes is attached perpendicularly. The rotation of the shaft 81a of the stepper motor 81 in one direction and its opposite causes the fork to move from right to left and vice versa.

[0064] In this [Fig. 3], the sleeve 39 is fully supported by the splines 34a1 of the driven pinion 34. The spline 38a1 of the hub 38 is fully exposed. The driven pinion 34 and the hub 38 are disengaged, in the so-called disengaged position. The transmission line 90, stopping at the hub 38, shows that the motor 20 is disengaged from the rear wheel (not shown) of the bicycle.

[0065] The fork actuator 80 is protected from the external environment by a cover 86.

[0066] Fig. 4 shows the drive unit 10 according to a second section passing through the shaft of the assist motor 20, the gear pair and pinion 24a, 34 of the reducer 30, the shaft 50 of the crankset, the shaft 83 of the fork 82 for moving the sliding sleeve 39 and the shaft of the stepper motor 81 of the actuator 80.

[0067] In this [Fig. 4], the sleeve 39 is supported by the splines 34a1 of the driven pinion 34 and the splines 38a1 of the hub 38. The driven pinion 34 and the hub 38 are thus locked together in the so-called dog clutch position. The transmission line 91, which runs from the rotor 23 to the toothed wheel 43, shows that the motor 20 is locked to the rear wheel (not shown) of the bicycle in both directions of rotation (no freewheel on the rear wheel).

[0068] Fig. 5 shows the drive unit 10 according to a third section passing through the shaft of the assist motor 20, the gear pair and pinion 24a, 34 of the reducer 30, the shaft 50 of the crankset, the shaft 83 of the fork 82 for moving the sliding sleeve 39 and the shaft of the stepper motor 81 of the actuator 80.

[0069] On this [Fig.5], the sleeve 39 is carried almost entirely by the splines 38al of the hub 38. It is important that it is also slightly carried by the splines 34a 1 of the driven pinion 34 in order to easily leave the blocking situation and move to the dog clutch or disengaged situation.

[0070] The sleeve 39 has axial teeth 39a on one face, opposite the motor housing 21. These teeth are engaged in notches 21a belonging to the motor housing 21 and lock the sleeve 39 in rotation.

[0071] The transmission line 91 which goes to the rotor 23, shows that the motor 20 is still attached to the rear wheel (not shown) of the bicycle in both directions of rotation (no freewheel on the rear wheel in this transmission line).

[0072] The transmission line 92 which goes from the notches 21a to the rear wheel via the toothed wheel 43, shows that the rear wheel (not shown) of the bicycle is locked in both directions of rotation (no freewheel on the rear wheel associated with the pinion of the transmission line of the electric motor 20).

[0073] This rear wheel lock in both directions of rotation has an anti-theft function.

[0074] Fig. 6 shows a flowchart of the incoming and outgoing information of a computer 200.

[0075] The incoming information is: • the speed of the bicycle 210 given by a dedicated sensor; • the pedaling speed 211 given by a dedicated sensor; • the battery charge level 212; • the level of assistance requested by the cyclist given by a dedicated 213 sensor associated with a rotating sleeve positioned on the side of the rear wheel brake handle; • the inclination of the path given by a slope sensor 214; • the presence of the ignition key 215 provided by a dedicated contactor; • activation of the ignition key 216 provided by a second switch dedicated; • the braking level given by a sensor 217 associated with the front brake handle; • the position of the control fork of the sliding sleeve 39 given by the top counter 218 of the stepper motor controlling the fork.

[0076] The outgoing and therefore control information is: • the 220 display screen documentation; • the 221 control for the disengagement sleeve, the engine engagement and the rear wheel locking; • the 222 control of the motor in assistance or recovery power level.

[0077] Here are some examples of actions of the computer depending on the information received.

[0078] The presence of the ignition key 215 causes the computer 200 to wake up.

[0079] Activating the ignition key 216 causes the sleeve control 221 and the The bicycle is unlocked, and by default, the electric motor is engaged as long as the battery charge level (212) is above the minimum level. Thus, the motor (20) is immediately available for starting assistance, triggered by pedaling detection from the dedicated sensor (72).

[0080] In the event of a battery charge level 212 less than or equal to the minimum charge level, the control 221 of the sleeve triggers the disengagement so that the cyclist does not suffer from electromagnetic drag, inertial drag of the motor and mechanical drag of the first stage of the reducer.

[0081] In the event of the charge level of the battery 212 being less than or equal to the minimum level, the control 221 of the sleeve triggers the dog clutch when the tilt sensor 214 indicates a downward slope, during braking requests (detector on front brake) and also when stopping pedaling is interpreted as a deceleration request and puts the electric machine 20 into generator mode.

[0082] In case of speed exceeding the regulatory speed limit, the assistance is interrupted.

[0083] The level of assistance is modified in order to respect, as far as possible, the cyclist's request according to the slope of the route: on an uphill slope by an increase, on a downhill slope by a decrease, a cancellation, or even a switch to recovery mode in the event that the speed exceeds the regulatory speed limit.

Claims

1. Demands Electric drive unit (10) for bicycle, arranged at the bottom bracket, comprising: • an electric motor (20); • a first reduction stage, comprising a driving gear (24a) machined at one end of the shaft (24) of the motor (20), a driven pinion (34) guided by a smooth ring (35) on a hollow shaft (36), itself guided by a needle bearing (37) on the shaft (50) of the pedal assembly. This reduction stage is contained in a space (30a) formed by the motor housing (21), the housing (31) of the reducer and its cover (32), which is sealed and contains a lubricant; • a fixed hub (38) secured to the hollow shaft (36) by splines (36a) and a sliding sleeve (39) whose internal splines cooperate with splines (38al) on the outer diameter of the hub (38) and with splines (34al) on the outer diameter of the bearing (34a) which extends laterally beyond the teeth of the driven pinion (34). The sliding sleeve (39) also has axial teeth (39a) on one of its lateral faces. • a sliding sleeve control device comprising a fork (82) carried by a shaft (83) passing through the motor housing (21), a shaft control arm (84) with a threaded bore (84a), a stepper motor (81) for actuating with a threaded shaft (81a) cooperating with the threaded bore (84a) of the control arm (84); • the hollow shaft 36, on its grooved end 36b, outside the closed space 30a, carries a toothed wheel 43 (also stopped by a ring), driving the second stage of connection of the electric motor 20 with the rear wheel without free wheel and linked to the driving wheel by a roller chain or a toothed belt (not shown); • a crankset comprising a shaft (50), with splines (50b) at each end for driving the two arms (51, 52) at the ends of which the pedals (not shown) are arranged, and a toothed chainring (54) fixed by means of

2. of a roller chain, of one or more sprockets which drive the rear wheel via a freewheel (not shown). • a freewheel (57) whose rollers have as a track a portion of the spacer (55) fixed in rotation to the shaft (50) of the crankset. • a calculator (not shown); • a first speed sensor (71) arranged on the cover (32), with notches (70a) cut into a target (70) for reading track carried by the hollow shaft (36) in permanent connection with the rear wheel (not shown) and providing the computer with the speed information of the bicycle. • a second speed sensor (72) arranged on the engine casing (21), has as its reading track the notches (55a) cut into the spacer (55) attached to the crankshaft (50) and provides the computer with the pedaling speed information. characterized in that the sliding sleeve (39), the movement of which is controlled by the stepper motor (81) driven by the computer, has three positions: • the first, when it is carried only by the splines (34a 1) of the driven pinion (34) of the reducer (30), corresponding to the disengagement of the motor (20) and the wheel, also called the disengagement position; • the second, when it is carried both by the splines (34a 1) of the driven pinion (34) of the reducer (30) and those (38al) of the fixed hub (38), corresponds to the joining of the motor and the wheel, also called the dog clutch position; • the third, when it is carried both by the splines (34a 1) of the driven pinion (34) of the reducer (30) and those (38al) of the fixed hub (38), and when its axial teeth (39a) are engaged in notches (21a) belonging to the motor housing (21), corresponds to the locking of the electric motor (20) and the rear wheel (not shown) and acts as an anti-theft device. Electric powertrain (10) for bicycle according to claim 1 characterized in that The freewheel (57) prevents the crankshaft (50) from turning in the opposite direction to forward motion (backpedaling) and its action, combined with that of the freewheel associated with the rear wheel sprocket(s) (not shown), prevents the bicycle from rolling backward and thus provides comfort when stopping and restarting uphill because it eliminates the need to use the braking devices associated with each wheel.

3. Electric powertrain (10) for bicycle according to claim 1 characterized in that it is controlled by the computer (200) which, based on the following input information: • the speed of the bicycle (210) given by a dedicated sensor; • the pedaling speed (211) given by a dedicated sensor; • the battery charge level (212); • the level of assistance requested by a dedicated sensor (213) associated with a rotating sleeve positioned on the side of the rear wheel brake handle; • the incline of the route given by a slope sensor (214); • the presence of the ignition key given by a switch (215); • the activation of the ignition key given by a second switch (216); • the braking level by a sensor (217) associated with the front brake handle;• The position of the sliding sleeve control fork given by the top counter (218) of the fork control stepper motor ensures: • the documentation (220) of the display screen; • the control (221) of the disengagement sleeve, motor engagement and rear wheel locking; • the control (222) of the motor in assistance power, according to the rider's request, or in recovery power.

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