WO2024052843A1 - Ligne d'arbres de transmission hybride à division de puissance pour un vélo électrique pour permettre la coupure d'une puissance d'assistance - Google Patents

Ligne d'arbres de transmission hybride à division de puissance pour un vélo électrique pour permettre la coupure d'une puissance d'assistance Download PDF

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Publication number
WO2024052843A1
WO2024052843A1 PCT/IB2023/058841 IB2023058841W WO2024052843A1 WO 2024052843 A1 WO2024052843 A1 WO 2024052843A1 IB 2023058841 W IB2023058841 W IB 2023058841W WO 2024052843 A1 WO2024052843 A1 WO 2024052843A1
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WO
WIPO (PCT)
Prior art keywords
ring gear
bicycle
rotation
output shaft
planet gears
Prior art date
Application number
PCT/IB2023/058841
Other languages
English (en)
Inventor
Benjamin Chetwood STRUVE'
Sandro Bonardo
Andrea Canestrari
Original Assignee
RAICAM DRIVELINE S.r.l.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by RAICAM DRIVELINE S.r.l. filed Critical RAICAM DRIVELINE S.r.l.
Publication of WO2024052843A1 publication Critical patent/WO2024052843A1/fr

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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
    • 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
    • B62M11/18—Transmissions characterised by the use of interengaging toothed wheels or frictionally-engaging wheels of changeable ratio with planetary gears with a plurality of planetary gear units

Definitions

  • the present invention pertains to the field of electrically powered bicycles (or “e-bikes”) with an electric motor assisting the rider’s pedal-power. More specifically, the present invention concerns an e-bike Power–split hybrid driveline for an electric bicycle to allow assistance power to be switched off. Background to the invention Power–split hybrid drivelines have been recently proposed for electric bicycles. Some of these systems include a pedal crankshaft for operation by a rider, an epicyclic gearing mechanism, an assist motor and a control motor. The epicyclic gearing mechanism is arranged to determine the transmission ratio between the pedal crankshaft and an output shaft for transmitting rotation to a rear wheel of the bicycle.
  • the epicyclic gearing mechanism is referred to as an epicyclic “power-split” gearing mechanism, because it is arranged to transfer power from the pedals to the rear wheel of the bicycle through two routes: a mechanical route and an electrical route. Specifically, the epicyclic gearing mechanism transmits power from the assist motor to the output shaft. Furthermore, the epicyclic gearing mechanism adjusts the rotational speed of the pedal crankshaft as a result of the operation of control motor.
  • the epicyclic hybrid driveline of the present disclosure pertains to so-called “I2” epicyclic driveline layouts for e-bikes.
  • a chain ring for driving the rear wheel is connected to a sun gear that is assisted by a traction motor or assist motor.
  • a ratio controlling motor is connected to a ring gear of the epicyclic gearing system for controlling the transmission ratio between the pedal crankshaft and the output shaft. As the speed of the bicycle increases, the ratio controlling motor assist increases the overall gear ratio value in order that the rotational speed of the pedals (i.e. the rotational speed of the pedal shaft) be maintained at a speed which is comfortable for the rider.
  • One of the most recent power–split hybrid drivelines for an electric bicycle provides an electric auxiliary drive system which comprises a pedal crankshaft, an epicyclic gearing mechanism, an assist motor for driving an output shaft, and a control motor for controlling, through the epicyclic gearing mechanism, the transmission ratio between the pedal crankshaft and the output shaft.
  • a first one-way clutch operatively connected to the control motor, is configured for blocking the rotation of a ring gear of the epicyclic gearing system in a forward direction of rotation while allowing its free rotation in the reverse direction of rotation.
  • a second one-way clutch is configured for drivingly connecting the assist motor to the output shaft when the assist motor is switched on, and for disengaging the assist motor from the output shaft when the assist motor is switched off but the output shaft continues rotation in the forward direction.
  • a pedal shaft is driving a planetary carrier having planets that are engaged by the outer ring gear, which is driven by the ratio controlling motor.
  • a sun gear is connected to the chain gear and a traction gear which is secured for rotation with the chain gear and the planetary carrier.
  • the chain gear is driven by traction motor M2.
  • a one-way clutch is associated with the ratio controlling motor, so that the ring gear may only turn in one direction.
  • the transmission ratio between the pedal crankshaft and the output shaft is determined by the gears of the epicyclic system.
  • the gears of the epicyclic system When the rider starts pedalling at low speed, the planets are pushing against the ring gear, which is locked in position by the one-way clutch and therefore provides the lowest transmission ratio.
  • the ratio controlling motor starts to spin, and the ring gear is rotated backwards, which slows down the pedals through the planets, relatively to the sun gear, so that the bicycle can keep a comfortable transmission ratio.
  • European legislation European legislation (European standard EN 15194: 2017 for Electrically power assisted cycles) demands that the electrical assistance is switched off above a certain road speed (25 km/h), in order to limit the potential velocity of the bicycle and to reduce the safety risk involved with riding this type of vehicle.
  • a limit encountered with the some of the current I2 epicyclic drivelines is that the biker is not allowed to comfortably push the bicycle pedalling beyond a pre-set limit speed, namely 25 km/h, at which the assistance of the electric motor(s) is automatically cut off.
  • a pre-set limit speed namely 25 km/h
  • the torque from the pedals is always reacted against the ratio controlling motor.
  • the ratio controlling motor increases in velocity in order to maintain a comfortable pedalling speed for the rider.
  • the ratio controlling motor supplies considerable mechanical power to the system which contributes to assisting the forward motion of the bicycle. If the ratio controlling motor is switched off, in order to comply with the legislative requirement to remove electrical assistance, the motor torque which counteracts the rider’s pedalling is removed.
  • the bicycle pedals spin freely which makes it impossible for the rider to continue pedalling.
  • a pre-set speed limit for example 25 km/h
  • the present invention provides an electric auxiliary drive system for a bicycle, having the features defined in claim 1. Preferred embodiments are defined in the dependent claims.
  • the present invention provides an electric auxiliary drive system for a bicycle, comprising: a pedal crankshaft for operation by a rider; an output shaft for transmitting rotation to a rear wheel of the bicycle; an epicyclic gearing mechanism arranged to determine a transmission ratio between the pedal crankshaft and the output shaft; an assist motor for driving the output shaft; a control motor, drivingly connected to the epicyclic gearing mechanism for controlling, through the epicyclic gearing mechanism, the transmission ratio between the pedal crankshaft and the output shaft.
  • At least one first one-way clutch is operatively connected between the control motor and a rigid element fixedly mountable to the bicycle frame, wherein the first one-way clutch is configured for blocking the rotation of a first ring gear of the epicyclic gearing system in a first, forward direction of rotation and for releasing and allowing free rotation of said first ring gear of the epicyclic gearing system in a second, reverse direction of rotation.
  • a second one-way clutch is operatively connected between the assist motor and the output shaft, wherein the second one-way clutch is configured for drivingly connecting the assist motor to the output shaft when the assist motor is switched on to drive the output shaft in a forwards direction, so as to assist in driving the bicycle forwards, and for disengaging the assist motor from the output shaft when the assist motor is switched off but the output shaft continues rotation in the forward direction.
  • the epicyclic gearing mechanism further comprises: a second ring gear and an associated locking device fixedly mountable to a bicycle frame and operable to engage and block the rotation of the second ring gear; a first and a second sun gear, both secured for rotation with the output shaft; a first set of planet gears between the first sun gear and the first ring gear, and a second set of planet gears between the second sun gear and the second ring gear, and a planet carrier which is secured for rotation with the pedal crankshaft and supports the first and the second sets of planet gears.
  • the first and second sun gears and the first and second sets of planet gears are configured to provide a desired transmission ratio between the pedal crankshaft and the output shaft for transmitting rotation to a rear wheel of the bicycle when the rotation of the second ring gear is locked by the locking device.
  • the present invention provides an electrically powered bicycle comprising a drive system as defined in the appended claims.
  • Fig.1 is a schematic cross-sectional view of the main components of an e-bike drive system according to an embodiment of the present invention
  • Fig.2 diagrammatically shows the torque split relationship through the epicyclic gear mechanism
  • Figs. 3 to 6 schematically depict the power flow within the system during different stages of bicycle acceleration
  • Fig.7 is a schematic cross-sectional view of the main components of an e-bike drive system according to an alternative embodiment of the present invention.
  • an e-bike drive system comprises two electric motors, M1, M2, and an epicyclic gearing mechanism 20 having an output shaft 21.
  • a chain ring 6 Secured for rotation with the output shaft 21 is a chain ring 6 that drives the rear wheel (not shown) of the bicycle.
  • Designated at 1 is a pedal shaft or crankshaft for operation by a rider R.
  • the pedal shaft 1 passes through the assembly and connects together two conventional pedal crank and foot support assemblies (not illustrated in the drawings) which are mounted outside the drive unit.
  • the pedal shaft 1 takes the torque and speed supplied by the rider and transfers it to the planetary carrier 2.
  • Electric motor M1 is termed “control” motor, or “ratio controlling” motor, because it drives a gear of the epicyclic gearing mechanism that controls the transmission ratio between the output shaft and the pedal crankshaft.
  • Electric motor M2 termed “assist” motor (or “traction” motor) herein, generates power that is transmitted to the output shaft 21 for moving the e-bike forwards.
  • the epicyclic gearing mechanism is also referred to as an epicyclic “power- split” gearing mechanism, because it is arranged to transfer power from the pedals to the rear wheel of the bicycle through two routes, as explained herein after: a mechanical route MR and an electrical route ER.
  • the assist motor M2 transmits power to the output shaft.
  • the epicyclic gearing mechanism adjusts the rotational speed of the pedal crankshaft 1 as a result of the operation of control motor M1.
  • the e-bike drive system is to be accommodated in a housing (not shown in the drawings), preferably mounted in use centrally within the frame of a bicycle (at the ‘bottom bracket’).
  • the housing provides mountings and reaction points with rolling bearings rotatably supporting the pedal crankshaft 1.
  • the housing may also contain an electronic controller C (shown in Fig.3) for the drive system.
  • the epicyclic gearing mechanism 20 comprises a planetary carrier 2 which supports two sets of planet gears, namely a first set of planet gears 3a and a second, supplementary set of planet gears 3b, and applies the rider’s torque and speed to the epicyclic gear system.
  • the planetary carrier 2 is secured for rotation with the pedal shaft 1.
  • the pedal shaft 1 takes the torque and speed supplied by the rider and transfers it to the planetary carrier 2.
  • the power split epicyclic gearing mechanism comprises a first sun gear 5a and a second sun gear 5b which are both integral with the chain ring 6 and the output shaft 21.
  • the first sun gear 5a and the second sun gear 5b may both be driven for rotation by the assist motor M2 through a traction gear 8 which is secured for rotation with the sun gears 5a, 5b and the chain ring 6.
  • the first sun gear 5a has external teeth which mesh with the first set of planet gears 3a.
  • the second sun gear 5b has external teeth which mesh with the second set of planet gears 3b.
  • the first set of planet gears 3a may be smaller, i.e. have a smaller diameter, than the second, supplementary set of planet gears 3b.
  • the first sun gear 5a has a larger diameter than the second sun gear 5b.
  • a first ring gear 4 has internal teeth which mesh with the first set of planet gears 3a, and external teeth which mesh with a pinion gear 9 driven directly by the ratio controlling motor M1.
  • the planet gears 3a of the first set are free to rotate relative to the planetary carrier 2 and hence apply an equal tangential force to the first ring gear 4 and the first sun gear 5a, regardless of the relative speeds of these components.
  • a second ring gear 16 has internal teeth which mesh with the second set of planet gears 3b.
  • the planet gears 3b of the second set may be supported around the same axes and at the same radius as the planet gears 3a.
  • the planet gears 3b of the second set may be mounted to the planet carrier 2 by a separate set of mounting pins which are mounted at a different radius.
  • a locking device 17 is mounted to the bicycle frame 22 or a rigid element fixedly secured thereto. The locking device 17 is operable to engage and stop the second ring gear 16 from rotating.
  • the locking device 17 may be made as an electromagnetic operated clutch as an electromagnetic pin that may be extended to or engage a corresponding locking seat, such as an opening or a recess, formed in the second ring gear 16.
  • the output shaft 21 may be a hollow tubular shaft through which the pedal shaft 1 passes.
  • the chain sprocket or belt sprocket 6 drives either a chain or a toothed belt 7 which drives the rear wheel of the bicycle.
  • the traction gear 8 has outer teeth which mesh with a second pinion gear 11 driven directly by the assist motor M2.
  • a first one-way clutch 10 may be arranged to releasably connect a shaft S1 of the ratio controlling motor M1 to a rigid element 22 fixedly secured to or integral with the bicycle frame.
  • the rigid, fixed element 22 may be a housing of the drive unit.
  • a supplementary one-way clutch 19 may be arranged between the pinion gear 9 and the shaft S1 of control motor M1. The purpose of the supplementary one-way clutch 19 is to lock the rotation of the first ring gear 4 when the control motor M1 is attempting to drive the first ring gear 4 in the reverse direction, so as to counteract the rider torque which is applied to the first ring gear 4.
  • the supplementary one-way clutch 19 allows free rotation of the first ring gear 4 when the control motor M1 is switched off but the first ring gear continues rotating in the reverse direction.
  • the second pinion gear 11 is connected to a shaft S2 of the assist motor M2 via a second one-way clutch 12.
  • the second pinion gear 11 meshes with the traction gear 8 so that assist motor M2 can assist in driving the bicycle forwards.
  • the second one-way clutch 12 that connects assist motor M2 with its pinion gear 11 is arranged so that it is engaged when the assist motor M2 is attempting to drive the traction gear 8 in the forward direction, so as to assist in driving the bicycle forwards.
  • the second one-way clutch 12 allows free rotation of the traction gear 8 when the assist motor M2 is switched off but the traction gear rotation continues to rotate in the forward direction.
  • the one-way clutches 10, 12, 19 may be, for example, in the form of a pawl and ratchet, or a sprag clutch with rollers which ride up ramps within a cage, or a belt or strap which is wrapped around a shaft. Due to the above arrangement, control motor M1, by controlling the speed of the first ring gear 4, controls the ratio between the speed of the pedals and the speed of the bicycle. Assist motor M2, by driving the traction gear 8, applies torque to the chain gear 6 and assists in moving the bicycle forwards.
  • the above described e-bike drive system functions in the following way.
  • Tc torque applied to the planetary carrier 2
  • Zr radius of the planetary carrier 2
  • Zs radius of the planetary gears 3a
  • Fr tangential force applied to the first ring gear 4
  • Fs tangential force applied to the sun gears 5a
  • the torque Tr is applied to the first ring gear 4 in a forward direction, however the first one-way clutch 10 is arranged to block the forwards rotation of the first ring gear 4. Hence the torque Tr is reacted by the first one-way clutch 10 and the first ring gear 4 remains stationary. All of the power supplied by the rider R is hence diverted to the sun gear 5a and via the chain gear 6 and the chain or belt 7, to the bicycle wheel.
  • the gear ratio between the pedals and the wheel of the bicycle is expressed as follows: Due to the action of the first one-way clutch 10, which allows rotation of the first ring gear 4 in the reverse direction but does not allow rotation in the forwards direction, the lowest overall gear ratio exists when the first ring gear 4 is stationary.
  • the ratios of the epicyclic gear system and the chain or belt ratio may be arranged so that the ratio with the first ring gear stationary equates to a suitable ratio for starting the bicycle from rest or climbing a steep hill.
  • this lowest ratio may have a numerical value of approximately 1:1 for a touring or commuter bicycle, meaning that one turn of the pedals gives about 1 turn of the rear wheel.
  • This transmission ratio is achieved by setting the number of teeth and diameters of the gears in the epicyclic system.
  • the traction motor M2 may be energised by the battery B through the controller C in order to provide assistance to the rider in moving the bicycle forwards.
  • the traction motor M2 applies torque via the second one-way clutch 12 and the pinion gear 11 to move the traction gear 8 in a forward direction and hence assist with the forward acceleration of the bicycle.
  • the second one-way clutch 12 is arranged so that it is locked when the traction motor M2 is applying torque to the traction gear 8 in the forward direction.
  • the overall gear ratio value As the bicycle starts to increase its speed, there is the requirement for the overall gear ratio value to increase, in order that the rotational speed of the pedals (i.e. the rotational speed of the pedal shaft 1) be maintained at a speed which is comfortable for the rider. This is achieved by energising the control motor M1 (Fig.4) in order to rotate the ring gear 4 in the reverse direction.
  • control motor M1 Wr * Tr
  • Tr is the torque applied to the ring gear 4 in order to react against the pedalling torque of the rider (as illustrated in Fig.2).
  • the locking device 17 continues to be not energised so that the second ring gear 16 is free to rotate, and no torque is transmitted through the planets to the supplementary sun gear 5b.
  • the bicycle continues to move forwards, assisted by power from the rider and the ratio controlling motor M1, and consequently the traction gear 8 continues to rotate in a forward direction.
  • a forward torque is no longer applied to the traction gear by traction motor M2, and consequently the second one-way clutch 12 unlocks, allowing the pinion gear 11 to rotate freely relative to the shaft of traction motor M2. Therefore, traction motor M2 is allowed to come to rest and it transmits no decelerating torque to the traction gear 8 or consequently to the wheel of the bicycle.
  • the locking device 17 continues to be not energised so that the second ring gear 16 is free to rotate, and no torque is transmitted through the planets to the supplementary sun gear 5b.
  • the supplementary epicyclic subsystem consisting of the second sun gear 5b and the associated second set of planets 3b, may advantageously be set in order to achieve a desired speed ratio between associated components of the system.
  • the diameter of the second sun gear 5b is smaller than the diameter of the first sun gear 5a
  • the diameter of the second set of planet gears 3b is larger than the diameter of the planets of the first set of planet gears 3a.
  • the ratio through the supplementary epicyclic subsystem should allow for a comfortable pedalling speed when the bicycle is travelling at the maximum legal assistance speed.
  • an overall gear ratio of 3.5 ensures a pedalling speed of approximately 60 rpm when the bicycle is travelling at the European maximum legal assisted speed of 25 km/h. Therefore, as the bicycle approaches the maximum legal assisted speed, the locking device 17 continues to be not energised so that the second ring gear 16 is free to rotate, and no torque is transmitted through the planets to the second or supplementary sun gear 5b.
  • the chosen gear ratio of the supplementary epicyclic subsystem the second ring gear 16 becomes stationary as the travelling speed of the bicycle reaches 25 km/h.
  • This stopping of rotation of the second ring gear 16 may for example be assisted, in order to be smooth, by slightly adjusting the pedalling speed by controlling the speed of control motor M1, in order to create the appropriate relationship between the road speed of the bicycle and the speed of the pedals, to ensure that the second ring gear becomes completely stationary.
  • the controller C activates the locking device 17 to lock the angular position of the second ring gear 16, preventing it from rotating.
  • the electromagnetic device may comprise a solenoid energised by the controller C.
  • the engagement of the locking device 17 and the resulting locking of the second ring gear 16 creates a supplementary torque path through the system from the pedal shaft 1 to the chain gear 6 which provides a fixed overall gear ratio between the pedal shaft and the rear wheel of the bicycle.
  • a suitable gear ratio between the pedal shaft and the rear wheel of the bicycle may range between 1:3 and 1:4.
  • a particularly comfortable gear ratio between the pedal shaft and the rear wheel of the bicycle is of approximately 1:3.5.
  • the main epicyclic system (the first sun gear 5a, the first set of planets 5a and the first outer ring 4) continues to rotate and electrical assistance may still be provided by motor M1, which provides torque to assist the first ring gear 4 rotating in the reverse direction.
  • the torque provided by the control motor M1 may now be progressively reduced in order to provide a smooth transition towards switching off the electrical assistance of the bicycle.
  • the control motor M1 may be switched off altogether.
  • the epicyclic gear system (particularly, the first sun gear 5a, the first set of planets 3a and the first ring gear 4) continue to rotate, however the one-way clutch 19 which connects the pinion gear 9 to the shaft S1 of control motor M1 disengages, because the control motor M1 is no longer applying torque through the clutch in a direction to assist the first ring gear 4 in turning in the reverse direction. Therefore, the control motor M1 is allowed to become stationary whilst the first ring gear 4 and the pinion 9 are allowed to continue rotating freely. Hence, the control motor M1 does not apply any regenerating or braking torque to the system.
  • the bicycle is driven forwards solely by the power from the rider’s pedalling action.
  • Torque at the pedal shaft 1 is transferred through the planetary carrier 2 to the supplementary or second set of planet gears 3b, which apply an equal tangential force to the teeth of the supplementary second ring gear 16 and the supplementary or second sun gear 5b.
  • the second ring gear 16 cannot turn due to engagement of the locking device 17, hence all of the rider’s pedalling power is transferred to the second sun gear 5b, with a fixed speed ratio, and hence is transmitted via the chain ring 6 and chain 7 to the bicycle rear wheel.
  • Fig. 7 a particularly compact alternative embodiment of the drive system is schematically depicted.
  • the supplementary epicyclic subsystem of Fig.7 comprises a supplementary or intermediate planet carrier 18 and a third set of supplementary planet gears 3c.
  • the intermediate planet carrier 18 has a set of radially outwardly facing teeth schematically depicted at 18c on a smaller diameter, and carries the third set of supplementary planet gears 3c supported freely rotating on pins 18d located at a diameter larger than that of the teeth 18c.
  • the supplementary planet gears 3c mesh radially inwardly with the second sun gear 5b, and radially outwardly with an inner toothing 16c of the second ring gear 16.
  • the second ring gear 16 provides a pair of axially adjacent inward toothings, one 16b for meshing with the second set of planet gears 3b, and one 16c for meshing with the supplementary planet gears 3c.
  • the supplementary planet gears 3c may be supported around the same axes and at the same radius as the planet gears 3a and/or 3b.
  • the supplementary planet gears 3c may be mounted to the intermediate planet carrier 18 on mounting pins which are arranged at a different radius with respect to planet gears 3a and/or 3b.
  • a similar overall ratio between the pedal and the wheel velocity may be achieved when the electrically operated locking device 17 is engaged and the second ring gear 16 is stationary but with a more favourable number of teeth on the second sun gear 5b and the second ring gear 16.
  • the second ring gear 16 typically has 98 teeth
  • the planet gears 3b of the second set may have 42 teeth
  • the second sun gear 5b may have 14 teeth.
  • the second sun gear 5b may be too small in diameter for the pedal shaft 1 to pass through its centre.
  • the alternative embodiment shown in Fig. 7 may provide a similar overall system ratio by using a second ring gear 16 having 76 teeth, a second set of planet gears 3b having 20 teeth and a set of supplementary planet gears having 16 teeth.
  • the teeth 18c on the intermediate planet carrier may be 36 in number
  • the second sun gear 5b may requires 44 teeth.
  • the outside diameter of the second ring gear 16 may be reduced by more than 20%, and the diameter of the second and smaller second sun gear 5b may be increased by more than 150%.
  • the drive system of the present disclosure provides several advantages and benefits: the epicyclic gear system allows the bicycle to be ridden at high speeds without any electrical assistance; the epicyclic gear system allows all of the functions and advantages of a power assisted bicycle when the electrical assistance motor is switched on; the system efficiency is optimised at higher road speed when the motors are both switched off because both the ratio control motor M1 and the traction motor M2 can be mechanically disconnected from the system when not required; there is no necessity for either of the motors to regenerate any electrical energy.

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Transportation (AREA)
  • Mechanical Engineering (AREA)
  • Structure Of Transmissions (AREA)

Abstract

Un système d'entraînement auxiliaire électrique pour un vélo comprend une manivelle de pédalier (1), un mécanisme d'engrenage épicycloïdal (20), un moteur d'assistance (M2) destiné à entraîner un arbre de sortie (21), et un moteur de commande (M1) destiné à commander, par l'intermédiaire du mécanisme d'engrenage épicycloïdal, le rapport de transmission entre la manivelle de pédalier (1) et l'arbre de sortie (21). Le mécanisme d'engrenage épicycloïdal (20) comprend en outre un premier (5a) et un second (5b) planétaire, tous deux fixés pour une rotation avec l'arbre de sortie (21). Un porte-satellites (2) est fixé pour tourner avec la manivelle de pédalier (1) et supporte un premier ensemble de satellites (3a) entre le premier planétaire (5a) et une première couronne (4), et un second ensemble de satellites (3b) entre le second planétaire (5b) et une seconde couronne (16). Un dispositif de verrouillage (17) permet de bloquer la rotation de la seconde couronne (16), permettant au cycliste de pousser le vélo au-delà d'une limite de vitesse prédéfinie, en ne reposant que sur sa puissance physique mécanique, sans être assisté(e) électriquement, tout en continuant à pédaler à une vitesse de rotation des pédales confortable.
PCT/IB2023/058841 2022-09-08 2023-09-07 Ligne d'arbres de transmission hybride à division de puissance pour un vélo électrique pour permettre la coupure d'une puissance d'assistance WO2024052843A1 (fr)

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IT202200009794A1 (it) 2022-05-12 2023-11-12 Raicam Driveline S R L Trasmissione ibrida a ripartizione di potenza per bicicletta elettrica

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