Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
  • B62M6/00—Rider propulsion of wheeled vehicles with additional source of power, e.g. combustion engine or electric motor
  • B62M6/40—Rider propelled cycles with auxiliary electric motor
  • B62M6/55—Rider propelled cycles with auxiliary electric motor power-driven at crank shafts parts
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
  • B62M—RIDER PROPULSION OF WHEELED VEHICLES OR SLEDGES; POWERED PROPULSION OF SLEDGES OR SINGLE-TRACK CYCLES; TRANSMISSIONS SPECIALLY ADAPTED FOR SUCH VEHICLES
  • B62M11/00—Transmissions characterised by the use of interengaging toothed wheels or frictionally-engaging wheels
  • B62M11/04—Transmissions characterised by the use of interengaging toothed wheels or frictionally-engaging wheels of changeable ratio
  • B62M11/14—Transmissions characterised by the use of interengaging toothed wheels or frictionally-engaging wheels of changeable ratio with planetary gears
  • B62M11/145—Transmissions characterised by the use of interengaging toothed wheels or frictionally-engaging wheels of changeable ratio with planetary gears built in, or adjacent to, the bottom bracket

Definitions

• TITLE POWERTRAIN WITH CONTROLLED TRANSMISSION FOR ELECTRICALLY ASSISTED BICYCLES
• the present invention relates to a powertrain for an electrically assisted bicycle and to an electrically assisted bicycle comprising such an actuator.
• the electrically assisted bicycle is experiencing very strong development both because it offers an easier mode of travel with the assistance it provides by avoiding using the car, it also offers assistance particularly on steep terrain and allows as many people as possible to practice cycling.
• the first type has a motor that acts directly on the hub of the rear wheel or the front wheel.
• the second type has a motor integrated directly into the crankset. This arrangement makes it possible to offer a more compact device and to relocate the center of gravity of the drive unit under the user.
• crankset is integral in rotation with the planet carrier of the reduction gear, the motor drives the planetary gear.
• the bicycle includes a reduction ratio changing device which may be a gear changing mechanism, for example with gears on the hub of the rear wheel with manual or automatic operation.
• a certain number of reduction ratios can be obtained, for example 6.
• Changing the transmission ratio is achieved by operating the gear shift mechanism. However, with each gear change, there is a torque break.
• a powertrain for an electrically assisted bicycle integrating a continuously variable transmission.
• the group comprises a first electric motor configured to provide assistance, an epicyclic gear reducer interposed between the output of the first motor and the crankset, a second electric motor configured to act on the epicyclic gear reducer so as to modify its reduction ratio .
• the bottom bracket shaft and the shaft carrying the plate are distinct, which makes it possible to simplify the production of the powertrain, in particular by reducing the number of hollow shafts required.
• crankset pinion and the first motor drive the planetary gear
• the planet carrier is mechanically connected to the chainring
• the second motor interacts with the crown, which is mounted movable in rotation, so as to modify its speed and thus to modify the reduction ratio of the planetary gear train.
• the gear change takes place automatically, which helps maintain optimal operating conditions for the first motor. Electricity consumption is then optimized and the lifespan of the motor is increased.
• the invention also makes it possible to easily implement different functions, for example that of freewheeling without having to add additional mechanical elements, and without this preventing other functions such as reverse assistance.
• the second motor is an electric motor which does not generate resistant torque, when it is driven mechanically, for example a motor without a magnet, in order to improve the comfort of the user when there is no assistance.
• an electromechanical brake is provided on the crown to immobilize the crown for example in very high torque phases, for example when starting on a slope. The brake then replaces the second motor and power consumption can be reduced.
• a subject of the present application is then a powertrain for an electrically assisted bicycle comprising a crankshaft extending along a first longitudinal axis, a first electric motor, an epicyclic gearbox, a second electric motor, a plate, the epicyclic gearbox and the plate having a second longitudinal axis parallel to and distinct from the first longitudinal axis, in which the epicyclic gearbox comprises an element d the input attacked by the crankshaft, the first motor, and an output element driving the plate and a toothed ring, in which the toothed ring is mounted movable in rotation around the second longitudinal axis of the epicyclic gearbox and in which the second electric motor is mechanically connected to said ring gear to rotate it, the powertrain being intended to be controlled by a control unit which is configured to control the first electric motor and the second electric motor, the control unit controlling the speed of rotation of the ring gear in order to change the reason of the epicyclic gearbox and the transmission ratio of the powertrain.
• the epicyclic gearbox comprises a sun gear, the gear ring, satellites meshing with the sun gear and the gear ring, a planet carrier carrying the satellites
• the sun gear forms the input element of the gearbox and the planet carrier forms the output element of the gearbox, or the planet carrier forms the input to the gearbox and the planetary carrier forms the output of the gearbox.
• one of the sun gear and the planet carrier preferably forms the input to the gearbox, while the other of the sun gear and the planet carrier forms the output of the gearbox.
• the plate is advantageously integral in rotation with the satellite carrier.
• the plate is attached to the planetary gear.
• the ring gear may include teeth on its inner periphery meshing with the satellites and teeth on its outer periphery meshing with a pinion driven by the second motor.
• the powertrain comprises immobilizing means for immobilizing the toothed ring on command, said immobilizing means advantageously comprising an electromechanical brake.
• the second motor is a magnetless motor.
• the crankshaft carries a pinion which is connected to the input element of the epicyclic gearbox by a gear train, and in which the first motor has on its output shaft a pinion meshing with a pinion secured to a shaft on which the input element of the epicyclic gearbox is fixed.
• Another subject of the present application is a powertrain system comprising a powertrain according to the invention and a powertrain control unit.
• the control unit may be configured to rotate the ring gear in a first direction and in a second direction.
• control unit is configured to provide a reverse assistance function in which it controls the first motor to rotate at slow speed in a first direction of rotation and the second motor to rotate in a second direction of rotation opposite to the first direction of rotation, so that the satellite carrier rotates in the second direction of rotation.
• Another subject of the present application is an electrically assisted bicycle comprising a frame, two wheels, including a driving wheel carrying a pinion, a power system according to the invention, pedals mounted on the crankshaft, an electric battery supplying the first electric motor and the second electric motor, a transmission element connecting the plate and the pinion of the driving wheel, at least one absolute position sensor of the first motor and at least one relative position sensor of the second motor, the unit control unit controlling the first motor and the second motor on the basis of the signals emitted by the sensors and the data deduced from these signals.
• FIG 1 is a schematic representation of an example of an electrically assisted bicycle comprising a powertrain according to the invention
• FIG 2 is a functional diagram of the powertrain according to a first embodiment
• FIG 3 is a functional diagram of the powertrain according to a second embodiment.
• the direction bike The direction bike.
• an electrically assisted bicycle V comprising a frame 2, a front wheel 4, a rear wheel 6, a crankset 8 provided with two pedals 10, a powertrain G1 arranged at the level of the crankset 8. Furthermore, the bicycle has a chainring 12 for transmitting the driving force to the rear wheel drive pinion 13 via a chain 15 or a belt.
• the driving force is applied to the front wheel.
• the crankset comprises a shaft Al with axis XI on the ends of which pedals 10 are fixed.
• the plate 12 has an axis X2 parallel to the axis XI and distinct from XI.
• the bicycle V also includes an electric battery B intended to power the powertrain in particular.
• the battery B is mounted on the frame, more particularly on the oblique tube 14. Alternatively it can be mounted at the level of the luggage rack.
• the powertrain Gl hereinafter designated “group”
• group comprises a reduction gear R, a first electric motor Ml intended to assist the user of the bicycle in generating the driving force, the first motor Ml can be designated “traction motor” and a second motor M2 intended to modify the reduction ratio of the reduction gear R.
• the motor M2 can be designated a “variator motor”.
• the reducer R is interposed between the shaft Al of the crankset and the plate 12.
• the reduction gear R is a reduction gear or planetary gear train comprising a sun gear 16, satellites 18 meshing with the sun gear 16, a planet carrier 20 carrying the satellites 18 and a ring gear 22 which meshes with the satellites.
• the reducer R and the plate 12 are coaxial.
• the shaft Al of the crankset comprises a first pinion PI of axis XI and integral in rotation with the shaft Al.
• the first pinion PI is connected to the sun gear 16 of the reduction gear R.
• the connection between the first pinion PI and the sun gear 16 comprises a second pinion P2 coaxial with the sun gear 16 and integral with that in rotation, a first idle gear P3 which meshes with the pinion PI and a second idle gear P4 which is coaxial and integral with the first idler gear P3.
• the second idler gear P4 meshes with the second pinion P2.
• the second pinion P2 and the sun gear 16 are carried by a shaft A2.
• a third pinion P5 is coaxial with the second pinion P2 and the sun gear 16 and is integral in rotation with them.
• the third pinion P5 is arranged between the second pinion P2 and the sun gear 16.
• the second pinion P2 is arranged between the sun gear 16 and the third pinion P5.
• the traction motor Ml includes an output shaft provided with a pinion P6 which meshes with the third pinion P5.
• the third pinion P5 is designated motor pinion P5.
• the second motor M2 comprises an output shaft carrying a pinion P7 meshing with teeth formed on the outer periphery of the crown.
• the pinion P7 meshes with the internal teeth of the crown, making it possible to avoid making external teeth on the crown.
• the motor M2 is intended to rotate the crown 22 on command.
• the crown 22 has teeth on its inner periphery which meshes with the satellites and teeth on its outer periphery which meshes with the pinion of the second motor M2.
• the plate P12 coaxial and integral in rotation with the satellite carrier 20 forms the outlet of the group.
• the plate 12 transmits the movement to the driving pinion of the rear wheel by a chain.
• a toothed belt is used.
• the crown 22 is advantageously mounted to move in rotation on the shaft A2 by means of a bearing.
• the crown is fixedly mounted on a hollow shaft A3 which receives the shaft A2 carrying the sun gear 16.
• the first motor Ml is for example a brushless or brushless motor in English terminology with a power for example between 100 W and 1000W.
• the epicyclic gearbox is of type I, however a powertrain using an epicyclic gearbox of type II, III or IV does not go beyond the scope of the present invention.
• mechanical or electromechanical immobilization means are provided to immobilize the crown 22 in rotation relative to the bicycle frame.
• these means include an electromechanical brake F which is tightened and immobilizes the crown in the absence of electrical power and is released, and leaves the crown 22 free to rotate, when the brake is supplied with electricity.
• the brake is installed in the M2 motor, it then benefits from the reduction ratio, which reduces the braking torque to be provided.
• the brake includes, for example, jaws which are tightened on the crown by means of a spring-type return system. The jaws are spread apart under the action of an electromagnet.
• the second motor M2 which ensures this immobilization function, by braking the rotor of the motor M2, an electrical consumption is then to be expected to ensure this immobilization.
• the powertrain G1 also includes a control unit UC intended to control the first motor Ml and the second motor M2 in operation information provided by different sensors.
• the axis of the motor Ml is provided with an absolute position sensor which makes it possible to synchronize the commands of the power switches in order to magnetize the phases of the motor in an appropriate sequence.
• M2 has its own relative position sensor or a speed-controlled sensor, in order to carry out speed control.
• the power consumption of M2 makes it possible to estimate the torque applied to the pedals by the cyclist. This information on the torque applied by the cyclist contributes to the management of the electrical assistance.
• the estimation based on the consumption of the M2 engine makes it possible to avoid having to resort to a specific, complex and high cost torque sensor.
• the speed of the crown 22 can vary continuously between a low value and a high value, the speed at the output of the reducer varies continuously.
• the crown speed control is controlled by the control unit UC on the basis of information provided by the various sensors mentioned above.
• the reduction ratio is reduced; the higher the speed of the crown, the closer the reduction ratio is to 1.
• the reduction ratio is that of the epicyclic gear train with fixed crown.
• the control unit UC then sends an activation control signal for the traction motor Ml, which rotates the pinion P5 which drives the planetary gear.
• the reduction ratio is that of the reducer R.
• the satellites and the satellite carrier are rotated, driving with them the plate 12 which drives the rear wheel via the chain or the belt.
• the bike is set in motion.
• the assistance provided by the motor depends on external measurements transmitted to the UC unit by the sensors stated above and by the power consumption of the second motor M2.
• the control unit sends a signal to the M2 motor to rotate the crown to modify the reduction ratio and thus assist pedaling despite the change in slope. Since the gear change is directly linked to the rotation speed of the crown, the gear change is continuous and therefore transparent for the user.
• the crankset being separated from the plate 12, it is possible for the user to maintain the same pedaling cadence while varying the speed of the bicycle depending on the slope.
• the control unit controls the M2 motor and therefore the rotation speed of the crown as best as possible to vary the transmission ratio and adapt it to the terrain.
• the pedaling frequency can be kept constant and the speed of the bicycle can vary, for example depending on the slope on which the bicycle is traveling.
• the motor M2 can be of lower power because the torque to be applied by it is reduced.
• the crown and the motor Ml rotate a first direction of rotation.
• the crown is rotated in a second rotation opposite to the first direction of rotation.
• a continuously variable transmission or continuously variable gearbox or CVT Continuous Variable Transmission in Anglo-Saxon terminology
• the bike no longer features a gear derailleur or other discrete ratio shifting system. There is then no longer a torque break when changing the transmission ratios. User comfort is significantly improved.
• the disadvantages linked to the derailleur are therefore eliminated, in particular the risks of derailment, its relative fragility and its maintenance. In addition, its mass is removed.
• the integrated continuously variable transmission of which we know the reduction ratio by the speed of M2 allows the measurement of the speed of the bicycle without the need to add a specific sensor on the wheels or another part of the bicycle.
• the number of speeds available is infinite since it is a continuous variation resulting from a continuous variation in the rotation speed of the crown.
• the second motor M2 has, for example, a power of between 1W and 100W.
• the second motor M2 is a motor which does not generate resisting torque or drag torque, when it is not powered, in particular in order to perform a freewheeling function and allow use of the bicycle without assistance with reduced effort, as will be described below.
• the second motor is a motor without a magnet, such as a switched reluctance motor or SRM motor (“switched reluctance motor” in English terminology).
• the ratio of the reduction gear between the Ml and planetary traction motor is between 1 and 10.
• the speed of the crown is between - 1000 rpm and + 1000 rpm.
• the plate 12 has between 10 and 40 teeth.
• the rear wheel pinion has between 10 and 60 teeth.
• the diameter of the wheels is between 254 mm (10 inches) and 737 mm (29 inches).
• the rotation speed imposed on the crown is equal to 700 rpm; using an epicyclic gearbox whose sun gear, satellites and ring gear have respectively 15, 39, 94 teeth, the ratio of the epicyclic gearbox is equal to 0.7404. Furthermore, the plate 12 has 20 teeth, the pinion of the rear wheel has 51 teeth and the wheels have a diameter of 700 mm.
• the speed of the bicycle is Tl km/h.
• the powertrain according to the invention has a large number of advantages.
• the transverse bulk can be reduced, and allow the integration of the group in an environment of 90 mm wide between the pedals, as desired by the manufacturers of electrically assisted bicycles.
• the powertrain has a larger footprint in the Y direction, which extends from the front to the rear of the bike, however this bulk is less problematic than the bulk in the X direction.
• the group is also easily adaptable to any type of electronically assisted bicycle by modifying the parameters of the control unit, for example it is easily adaptable to different wheel diameters. This modification is easily done by factory programming. It can even be considered to modify the parameters during the life of the bicycle, if the user wishes to change the diameter of the wheels or another characteristic taken into account for determining the transmission. This new setting is achieved by a software update.
• electrically assisted bicycles include a freewheel function that disconnects the traction motor and the drive wheel if no assistance is required, for example when the speed of the bicycle is higher than the maximum assistance speed.
• a freewheel function that disconnects the traction motor and the drive wheel if no assistance is required, for example when the speed of the bicycle is higher than the maximum assistance speed.
• such a function is generally obtained by additional mechanical means.
• locking means between the rotor of the traction motor and the planetary gear are implemented.
• the powertrain according to the invention directly integrates this function.
• This freewheel function is obtained by allowing the crown 22 to rotate freely, which disconnects the traction motor from the drive wheel, the reduction gear no longer providing a reduction function.
• This freewheel function can advantageously be obtained by using a reduction motor M2 which generates little or no resisting torque when driven by an external force, i.e. when the crankset alone drives the planetary carrier via the sun gear. and satellites. This freewheel function ensures great pedaling comfort for the user, especially when the battery is discharged.
• the control unit actuates the second motor to rotate the crown in order to compensate for the resistant torque and generate smooth pedaling feedback to the user without assistance.
• This operating mode nevertheless consumes energy; it can be implemented with a low battery state of charge, if appropriate management of the battery state of charge is implemented.
• the powertrain according to the invention can be controlled by the control unit to integrate an anti-theft function. For example, when a case of attempted theft is detected, the first motor Ml is deactivated and the second motor M2 is rotated so that the transmission ensures that an action on the pedals by the thief generates a very slow speed of the bicycle and renders the bicycle unusable. For example, for a two-wheeled bicycle, the speed is slow enough to prevent balance, and therefore to prevent using the bicycle.
• the battery management is advantageously such that sufficient power is available to activate the M2 motor.
• the powertrain according to the invention also makes it possible to provide the reverse assistance function.
• Either the traction motor is controlled to rotate in the second direction of rotation.
• first motor Ml is activated to rotate in the first direction of rotation but at slow speed
• second motor M2 is activated to rotate in the second direction of rotation.
• the direction of rotation of the planet carrier can then be reversed and thus generate reverse gear.
• This operating mode allows the free wheel to be kept on axis A2.
• the reverse assist function is particularly interesting for cargo bikes.
• State-of-the-art electrically assisted bicycles generally incorporate a mechanical freewheel which uncouples the traction motor from the drive wheel in reverse. Reversing assistance is then not available.
• the powertrain according to the invention may include means for immobilizing the crown in rotation. These means are particularly advantageous when operating at high torque and low speed. Thanks to the immobilization means, it is not the second motor which ensures this immobilization. These immobilization means, in the case of an electromechanical brake, can consume electrical energy but relatively little compared to what the second motor would consume to ensure the same immobilization. Preferably, the brake is applied in the absence of electrical power so it does not consume electrical energy to secure the crown, for example under the action of a spring-type return system.
• control unit controls the variator motor so as to rotate the crown in the opposite direction in order to increase the ratio of the reduction gear, which makes it possible to relieve the traction motor.
• the powertrain according to the invention can also be adapted to carry out regenerative braking, since the freewheeling function is obtained on command.
• the control unit is configured to control the ring gear and the first motor so that it operates as a generator.
• the powertrain according to the invention makes it possible to know the speed of the bicycle from the speed of the crown which is set by the control unit. This speed can be displayed on a screen to inform the user and/or allows the speed of the bike to be limited.
• the maximum speed of an electrically assisted bicycle varies depending on local speed legislation. For example in the European Union, the maximum authorized speed is 25 km/h and in the USA it is 33 km/h. the invention makes it easy to adapt the group to local legislation.
• the pedaling cadence is known by the speed of the motor Ml and the speed of the crown.
• the torque at the pedal can also be deduced by measuring the supply current of the variator motor M2, which eliminates the need for a torque sensor which is expensive.
• battery management is optimized to make it possible to maintain a very low power supply to the M2 motor, ensuring an acceptable transmission ratio for the user and allowing him to reach his destination point relatively easily.
• Group G2 differs from group G1 in that the gearbox R' includes the planet carrier 20' as an input element and the sun gear 16' as an output element.
• the pinion P2 and the planet carrier 20' are carried by a shaft A2' of axis X2.
• the crown is also fixed on a hollow shaft which is mounted around a shaft A4 carrying the sun gear 16' and the plate 12, of axis X2. Its manufacturing is also simplified.
• crankshaft therefore attacks the planet carrier and the plate 12 is integral in rotation with the planetary gear.
• the G2 powertrain is satisfactory, however moving the crown requires applying a greater torque than in the Gl group.
• a more powerful M2 variator motor is then used, which increases the mass of the group and its size.
• the powertrain according to the invention offers great pedaling comfort for the user while being relatively simple and robust.
• the fact of implementing two separate axes for the crankset and for the chainring makes it possible to limit the width of the powertrain and to integrate it more easily between the pedals.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Transportation (AREA)
• Mechanical Engineering (AREA)
• Retarders (AREA)
• Transmission Devices (AREA)

Applications Claiming Priority (2)

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• 2022
  • 2022-03-21 FR FR2202477A patent/FR3133589B1/fr not_active Expired - Fee Related
• 2023
  • 2023-02-22 WO PCT/FR2023/050251 patent/WO2023180643A1/fr not_active Ceased
  • 2023-02-22 EP EP23711509.2A patent/EP4496740A1/de active Pending

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