Pedally propelled vehicle drive system with crank torque controller and method for controlling a gear shift sequence in such system

Abstract

A pedally propelled vehicle drive system (1) and method for controlling a gear shift sequence in such system, comprising; - a crankshaft (3) configured to be rotatably driven by a rider's pedaling input, - a gear system (10) with multiple selectable gear ratios, wherein the gear system has a gear input shaft (10a) and a gear output shaft (10b), and is configured to provide an output torque in an output torque direction on the gear output shaft (10b) when an input torque in an input torque direction is present on the gear input shaft (10a), - a torque controller (70, 700) driven by the crankshaft (3), wherein the torque controller is configured to selectively alter the first torque by temporarily preventing at least a portion of the first torque from reaching the gear input shaft (10a) during a gear shift sequence.

Description

PEDALLY PROPELLED VEHICLE DRIVE SYSTEM WITH CRANK TORQUE CONTROLLER AND METHOD FOR CONTROLLING A GEAR SHIFT SEQUENCE IN SUCH SYSTEM TECHNICAL FIELD

[0001] The present invention relates to an improved gear shift system for a pedally propelled vehicle. The invention is of specific relevance for vehicles with multiple gears, where shifting is performed under torque. Such vehicles could be e.g., pedally propelled vehicles where the pedalling is assisted by a motor, such as for an electric bicycle, but it may also be implemented in relation to gear shifting of multi-speed gear systems where no such motor-assist is available.BACKGROUND

[0002] As described initially, the invention can be used in a wide range of applications. One such application is pedally propelled vehicles.

[0003] Most pedally propelled vehicles, such as bicycles are equipped with some sort of selectable gear ratio to improve pedaling efficiency and comfort.

[0004] Different from gears in other types of vehicles that are motor driven, where a gear shift system and motor drive system can co-operate during the gear shift, a bicycle control system is not able to control the rider and the torque from the rider on the pedals in the same way.

[0005] Experienced riders have therefore developed their own understanding and application of a shifting scheme. The optimum shifting scheme will depend on the type of bicycle, the characteristics of the rider etc., which means that practically no shifting schemes will be the same.

[0006] This is cumbersome, and one can easily observe that less experienced, and even experienced riders struggle to shift gears efficiently in certain situations.

[0007] With the introduction of electrical bikes, where pedaling is supported by a motor drive, the same problem remains. The shift control system can control the contribution from the motor, but not from the rider.

[0008] While many experienced riders in the sport segment have accepted and even appreciate developing their own shifting scheme, shifting remains a hurdle for many riders, and for any pedally propelled vehicle with motorized support, such as standard pedelecs, moped style e-bikes, electric cargo vehicles with two or more wheels, mountain bikes,leisure bikes, commuter bikes etc., this problem is increasing with the number of such vehicles and riders affected.

[0009] The pedaling rate is defined as the number of revolutions of the crank shaft per unit time. This is also termed the cadence and is mostly defined as rounds per minute (rpm).

[0010] Although an optimal cadence is unique for every rider, it is clear that the human physiology in general does not allow large variations in cadence in order to maintain efficient power production and comfort.

[0011] Most modern bicycles are therefore equipped with some sort of variable gear mechanism to vary the relationship between the cadence and the rotational speed of the drive wheel. By changing the gear ratio, the desired cadence can be selected for different speeds and different cycling conditions, such as e.g. uphill or downhill.

[0012] The gear shift is performed by a gear shift mechanism. The type of gear shift mechanism will depend on the type of gear system used in the specific case.

[0013] However, efficient shifting of gears on a bicycle requires precision and timing. Experienced riders know that they should shift close to the dead point of the crank to reduce the torque from the riders feet present on the gear mechanism. A large torque makes shifting more difficult and will usually reduce the lifetime of the shift mechanism and the transmission.

[0014] E-bikes add more complexity to the gear shifting. In addition to the torque from the rider, the torque from the motor should be taken into account as well. If the experienced rider eases off the pedals for shifting, the shifting mechanism will still struggle if a large torque from the electric motor is present. Vice - versa will a large torque from the rider represent a problem for shifting, even in the event that the control system is able to reduce the torque from the motor during shifting temporarily. Automatic gear shifting may further complicate this, since the rider does not know when the control system is going to perform the gear shift.

[0015] All high efficiency, dog brake based mechanical stepped transmissions will have challenges during gear shifts. This will affect all down shifts, and depending on architecture, also some upshifts.

[0016] More specifically the following challenges remain to be solved:- Separate clutches under torque. The clutches will be harder to separate with increased torque. With a given shift mechanism, a certain torque threshold is given- Engage the correct gear after shifting. Shifting gears using high forces can result in high wear on shift mechanisms as well as the ghost shifts.- Reduce shock loads in drive line components after completed high load gear shifts.

[0017] There are two sources for the torque input, the controllable motor, as well as the less controllable rider. If the rider torque is low and the motor input is high, a gear shift can be performed quickly reducing the motor torque, perform the gear shift and reapply motor torque in a controlled manner. Low rider torque is often unpredictable, and to select pedal in a 12-6 position (i.e. vertical crank arms) is often chosen to increase the probability. The result is a delayed gear shift and a loss of output torque during the shift and the post shift torque reloading.

[0018] In situations with constant high rider input torque, a gear shift is not possible, thus, the rider torque into the transmission must be reduced.

[0019] In a typical gearshift known from all types of dog brake and pawl operated transmissions as well as derailleurs, there is a short torque interruption where the rider will feel a short crank rotation without resistance. This is more pronounced with high torque shifts and larger gear steps, typically seen on eMTBs. This torque interruption is not only uncomfortable for the rider but will create an uncontrolled shock in the driveline - the typical reason for chain and sprocket damage and reduction of frame components and driveline service life.

[0020] Thus, there is a need for an improved shifting mechanism that takes the responsibility for smooth and efficient shifting off the experienced or less experienced rider.

[0021] US2024375747A1 discloses a drive arrangement for a vehicle with a multi-stage planetary gearing system that allows for variable transmission ratios. Similarly, US 20240059372 Al describes a pedally propelled vehicle gear system that uses a control system to manage torque during gear shifts.SHORT SUMMARY

[0022] The present invention relates to a pedally propelled vehicle drive system that comprises a torque divider, and a method and a control system for controlling gear shifting of a pedally propelled vehicle with a crankshaft 3 and a gear system 10 with multiple selectable gear ratios according to the independent claims.

[0023] One of the advantages of the drive system is enhanced gear shifting under load.

[0024] Overall, the invention addresses the challenges of separating the clutches under torque, reducing wear and reducing ghost shifts as well as reducing shock loads in drive line components after completed high load gear shifts.

[0025] In some embodiments the invention may have other advantages over existing drive systems, such as reducing mechanical stress and enhancing the overall efficiency of the drive system. The configuration allows for smoother gear transitions, particularly under load conditions, improving the riding experience for users.

[0026] The invention ensures precise torque management, contributing to the system's reliability and durability.

[0027] The invention solving the above-mentioned problems is a pedally propelled vehicle drive system, a method for controlling a gear shift sequence in a pedally propelled vehicle drive system and control system for a pedally propelled vehicle drive system, according to the independent claims.BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Fig. la illustrates schematically an embodiment of the pedally propelled vehicle drive system 1 with a torque controller 700 arranged concentrically about the crankshaft 3, where the motor 20 drives the input of the gear system 10.

[0029] Fig. lb illustrates schematically the torque controller 700 of Fig. 1 in more detail.

[0030] Fig. 2 illustrates schematically an embodiment of the pedally propelled vehicle drive system 1 with a torque controller 700 arranged concentrically about the crankshaft 3, where the motor 20 drives the output of the gear system 10.

[0031] Fig. 3a illustrates schematically an embodiment of the pedally propelled vehicle drive system 1 with a torque controller 70 arranged in parallel with the crankshaft 3, where the motor 10 drives the input of the gear system 10.

[0032] Fig. 3b illustrates schematically the torque controller 70 of Fig. 3a in more detail. Fig. 4

[0033] Fig. 4 illustrates schematically an embodiment of the pedally propelled vehicle drive system 1 with a torque controller 70 arranged in parallel with the crankshaft 3, where the motor 10 drives the output of the gear system 10.

[0034]

[0035] Fig. 5 is a schematic diagram illustrating torque and control flow of an embodiment of a pedally propelled vehicle drive system. This embodiment allows torque-fill by the motor during the gear shift sequence.

[0036] Fig. 6 is a schematic diagram illustrating torque and control flow of an embodiment of a pedally propelled vehicle drive system.

[0037] Fig. 7 illustrates a typical downshift sequence with torque fill to achieve higher cadence and / or lower crankshaft torque.

[0038] Fig. 8a, b, c, d, e, f illustrate the torque and cadence curves in Fig. 7 separately.

[0039] Fig. 9 illustrates in a perspective view an embodiment of a torque controller 70 that could optionally be applied in the pedally propelled vehicle drive system 1 shown in Fig. 3a and 3b.

[0040] Fig. 10 illustrates the same torque controller as in Fig. 9, in an exploded view.

[0041] Fig. 11 illustrates a section view of the torque controller in Fig. 9 and 10 where the crank brake 80 of the torque controller is in a disengaged state.

[0042] Fig. 12 illustrates a section view of the torque controller in Fig. 9 and 10 where the crank brake 80 of the torque controller is in an engaged state.

[0043] Fig. 13 illustrates in a perspective view an embodiment of a torque controller 700 that could optionally be applied in the pedally propelled vehicle drive system 1 shown in Fig. la and lb.

[0044] Fig. 14 illustrates the internals of the torque controller in Fig. 9, in a partly exploded view.

[0045] Fig. 15 illustrates in a drawing an embodiment of the crank drive 40 seen from the side.EMBODIMENTS OF THE INVENTION

[0046] In the following description, various examples and embodiments of the invention are set forth in order to provide the skilled person with a more thorough understanding of the invention. The specific details described in the context of the various embodiments and with reference to the attached drawings are not intended to be construed as limitations. Rather, the scope of the invention is defined in the appended claims.

[0047] The embodiments described below are numbered. In addition, dependent embodiments defined in relation to the numbered embodiments are described. Unless otherwise specified, any embodiment that can be combined with one or more numbered embodiments may also be combined directly with any of the dependent embodiments of the numbered embodiment(s) referred to.

[0048] In general the term "wheel" is used in this document. A wheel may have different implementations depending on the context. In some configurations the wheel can be a pulley, and in other configurations it may be a gearwheel.

[0049] When the speed of axles or shafts is mentioned, this should be understood as rotational speed.

[0050] In an independent embodiment ED01, the invention is a pedally propelled vehicle drive system (1) comprising;- a crankshaft (3) configured to be rotatably driven by a rider's pedaling input,- a gear system (10) with multiple selectable gear ratios, wherein the gear system has a gear input shaft (10a) and a gear output shaft (10b), and is configured to provide an output torque in an output torque direction on the gear output shaft (10b) when an input torque in an input torque direction is present on the gear input shaft (10a),- a torque controller (70, 700) driven by the crankshaft (3), wherein the torque controller is configured to selectively alter the first torque by temporarily preventing at least a portion of the first torque from reaching the gear input shaft (10a) during a gear shift sequence.ED02: The pedally propelled vehicle drive system 1 of ED01, wherein the torque controller (70, 700) is configured to re-direct at least some of the first torque to a torque sink.ED03: The pedally propelled vehicle drive system 1 of ED01 or ED02, wherein the torque controller 70, 700 is configured to convert torque into thermal energy.ED04: The pedally propelled vehicle drive system 1 of ED02 or ED03, wherein torque sink is configured to receive thermal energy from the torque controller (70, 700).ED05: The pedally propelled vehicle drive system 1 of any of ED01 to ED04, wherein the torque controller (70, 700) comprises a crank brake 80, configured to at least partly prevent rotation of the crankshaft (3).ED06: The pedally propelled vehicle drive system 1 of ED05, wherein the crank brake 80 is a friction brake, wherein at least some of the first torque is converted to thermal energy.ED07: The pedally propelled vehicle drive system 1 of ED05 or ED06, wherein the crank brake 80 is a multi-plate brake.ED08: The pedally propelled vehicle drive system 1 of ED07, wherein the crank brake comprises alternating steel and friction plates 81, 82 arranged inside a brake basket 85. ED09: The pedally propelled vehicle drive system 1 of ED08, wherein the steel plates 81 or friction plates 82 are rotationally fixed to the basket 85.ED10: The pedally propelled vehicle drive system 1 of any of ED05 to ED09, wherein the crank brake 80 is configured to provide a variable torque transfer from the crankshaft 3 to the torque sink.ED11: The pedally propelled vehicle drive system 1 of any of ED05 to ED10, wherein the crank brake 80 comprises a brake actuator 84 configured to disconnect and connect the plates in the multi-plate brake.ED12: The pedally propelled vehicle drive system 1 of ED11, wherein the brake actuator 84 comprises a pressure plate 184 arranged on top of the multiple brake plates inside the brake basket 85 and a brake lever 193 arranged to push the pressure plate 184 to compress the multiple brake plates to engage the brake.ED13: The pedally propelled vehicle drive system 1 of ED12, wherein the brake lever 193 is arranged to release the support plate 184 to de compress the multiple brake plates to disengage the crank brake.ED14: The pedally propelled vehicle drive system 1 of any of ED03-09 to ED03-10, wherein the crank brake further comprises a resilient torque restrictor configured to restrict maximum torque from the lever arm 193 to the pressure plate 184.ED15: The pedally propelled vehicle drive system 1 of any of ED11 to ED13, wherein the brake actuator (84) further comprises a preloaded spring (182) configured to act as a torque limiter by limiting axial compression force on the brake plates.ED16: The pedally propelled vehicle drive system of any of claims ED11 to ED14, wherein the brake actuator (84) is configured to compress a stack of brake plates to vary the braking force.ED17: The pedally propelled vehicle drive system 1 of any of ED01 to ED16, wherein the torque controller (70, 700) comprises a third one-way clutch (71) configured to permit backward rotation of the crankshaft (3) when the torque controller (70, 700) prevents at least a portion of the first torque from reaching the gear input shaft.ED18: The pedally propelled vehicle drive system of any of ED01 to ED18, wherein the torque controller (700) is arranged concentrically about the crankshaft (3).ED19: The pedally propelled vehicle drive system of any of ED01 to ED18, wherein the torque controller (70) is arranged non-concentrically in parallel with the crankshaft (3) ED20: The pedally propelled vehicle drive system of ED19, wherein the torque controller (70) is operatively coupled to the crankshaft 3 via a crank chain (45).ED21: The pedally propelled vehicle drive system 1 of any of ED01 to ED20, comprising a motor 20 configured to contribute with a second torque on the gear input shaft 10a or the gear output shaft 10b. I.e., the motor is connected to the input shaft or the output shaft, respectively.In the case where the motor is configured to contribute with the second torque on the gear input shaft 10a, he total torque on the gear input shaft 10a is the sum of the first and second torques.ES01: The pedally propelled vehicle drive system 1 of any of ED01 to ED21, comprising a crank torque sensor configured to detect torque applied to the crankshaft (3).ES02: The pedally propelled vehicle drive system 1 of ES01, comprising a crank speed sensor configured to detect a rotational speed of the crankshaft (3).ES03: The pedally propelled vehicle drive system 1 of ES01 or ES02, comprising a gear shift actuator 11, configured to change gears in the gear system 10.ES04: The pedally propelled vehicle drive system 1 of any of ES01 to ES03, comprising a gear position sensor, configured to detect the currently selected gear position in the gear system 10.

[0051] EG01: The pedally propelled vehicle drive system 1 of any of ED01 to ED21 or any of ES01 to ES04, comprising a control system 100 configured to control the torque controller (70, 700).

[0052] EG02: The pedally propelled vehicle drive system 1 of EG01, wherein the control system 100 is configured to;- monitor torque applied to the crankshaft (3),- detect or initiate an impending gear shift event in the gear system (10),- actuate the torque controller (70, 700) in response to the detected gear shift event to temporarily reduce the first torque transmitted to the gear input shaft (10a).

[0053] EG03: The pedally propelled vehicle drive system 1 of EG01 or EG02, wherein the control system 100 is configured to increase the second torque in response to the detected gear shift event.

[0054] EG04: The pedally propelled vehicle drive system 1 of any of EG01 to EG03, wherein the motor is configured to drive the gear input shaft 10a, and wherein the control system 100 is configured to increase the second torque when the first torque decreases during a gear shift sequence to maintain a stable total torque on the gear input shaft 10a during an initial part of the gear shift sequence.

[0055] EG05: The pedally propelled vehicle drive system 1 of EG04, wherein the control system 100 is configured to decrease the second torque when the first torque increases during a gear shift sequence to maintain a stable total torque on the gear input shaft 10a during a final part of the gear shift sequence.

[0056] EG06: The pedally propelled vehicle drive system 1 of EG04 Or EG05, wherein the control system 100 is configured to momentarily reduce or cancel the second torque contribution after the initial part of the gear shift sequence.

[0057] EG07: The pedally propelled vehicle drive system 1 of EG06, wherein the control system 100 is configured to momentarily reduce the second torque contribution until the total torque contribution is below a transmission shift threshold TST for the current gear shift sequence for the gear system (10).

[0058] EG08: The pedally propelled vehicle drive system 1 of any of EG01 to EG03, wherein the motor is configured to drive the gear output shaft 10b, to reduce the torque required for shifting, and allow the gear shift to take place.

[0059] EG09: The pedally propelled vehicle drive system 1 of EG08, wherein the control system 100 is configured to decrease the second torque when the first torque increases during a gear shift sequence. EG10: The pedally propelled vehicle drive system 1 of any of EG01 to EG08, wherein the control system 100 is configured to; provide a torque fill, such that torque on the driving wheel is maintained during the shift.

[0060] In an independent embodiment EM01, the invention is a method for controlling a gear shift sequence in a pedally propelled vehicle drive system 1, comprising;- temporarily preventing at least a portion of a first torque from a crankshaft 3 from reaching a gear input shaft 10a of a gear system (10) with multiple selectable gear ratios, during the gear shift sequence.

[0061] EM02: The method of EM01, comprising;- at least partly preventing rotation of the crankshaft (3) during the gear shift sequence.

[0062] EM03: The method of EM03, comprising;- reducing rotational speed of the crankshaft (3) with a friction brake.

[0063] EM04: The method according to any of EM01 to EM03, wherein the pedally propelled vehicle drive system 1 comprises;- a crankshaft (3) configured to be rotatably driven by a rider's pedaling input,- a gear system (10) with multiple selectable gear ratios, wherein the gear system has a gear input shaft (10a) and a gear output shaft (10b), and is configured to provide an output torque in an output torque direction on the gear output shaft (10b) when an input torque in an input torque direction is present on the gear input shaft (10a),- a torque controller (70, 700) driven by the crankshaft (3), wherein the torque controller is configured to selectively alter the first torque by temporarily preventing at least a portion of the first torque from reaching the gear input shaft (10a) during a gear shift sequence, wherein the method comprises;- monitor torque applied to the crankshaft (3),- detect an impending gear shift event in the gear system (10),- actuate the torque controller (70, 700) in response to the detected gear shift event to temporarily reduce the first torque transmitted to the gear input shaft (10a).

[0064] EM05: The method according to EM04, comprising;- releasing the torque controller (70, 700) to increase the first torque transmitted to the gear input shaft (10a).

[0065] EC06: The method according to any of EM01 to EM05, wherein the pedally propelled vehicle drive system (1) comprises a motor 20 configured to contribute with a second torque on the gear input shaft 10a or the gear output shaft 10b.

[0066] , In the case where the motor is configured to contribute with the second torque on the gear input shaft 10a, the total torque on the gear input shaft 10a is the sum of the first and second torques, wherein the method comprises;- controlling the second torque.

[0067] EM07: The method according to EM06, wherein the motor is configured to drive the gear input shaft 10a, the method comprising;- increasing the second torque when the first torque decreases during a gear shift sequence to maintain a stable total torque on the gear input shaft 10a during an initial part of the gear shift sequence.

[0068] EM08: The method according to EM06 or EM07, comprising;- decreasing the second torque when the first torque increases during a gear shift sequence to maintain a stable total torque on the gear input shaft 10a during a final part of the gear shift sequence.

[0069] EM09: The method according to EM07 or EM08, comprising;- momentarily canceling or reducing the second torque contribution after the initial part of the gear shift sequence.

[0070] EM10: The method according to EM09, comprising;- momentarily canceling or reducing the second torque contribution until the total torque contribution is below a transmission shift threshold TST for the current gear shift sequence for the gear system (10).

[0071] EM11: The method according to EM09 or EM10, comprising;- detecting a change of gear ratio in the gear shift system 10,- momentarily re-applying at least some of the second torque contribution.

[0072] EM12: The method according to any of EM01 to EM11, comprising;- adjusting the torque controller 70, 700 operation based on predefined riding modes, including at least one of: a comfort mode, a sport mode, and an automatic shifting mode.

[0073] EM13: The pedally propelled vehicle drive system 1 of any of EM01 to EM06, , wherein the motor is configured to drive the gear input shaft 10a, the method comprising - increasing the second torque to reduce the torque required for shifting, and allow the gear shift to take place.

[0074] EM14: The pedally propelled vehicle drive system 1 of EM13, comprising decreasing the second torque when the first torque increases during a gear shift sequence.

[0075] EM15: The pedally propelled vehicle drive system 1 of any of EM01 to EM14, comprising providing a torque fill, such that torque on the driving wheel is maintained during the shift.

[0076] In an independent embodiment EC01 the invention is a control system (100) for a pedally propelled vehicle drive system (1), implementing the features of any of the methods EM01 to EM11.

[0077] In the following sections, specific embodiments will be presented with reference to the figures provided.

[0078] In the embodiment illustrated in Fig. la, the pedally propelled vehicle drive system 1 comprises a crankshaft 3 with first and second crank arms 3a, 3b and a gear system 10 with multiple selectable gear ratios between an input shaft 10a and an output shaft 10b.

[0079] The gear ratio can be shifted by operating the gear shift actuator 11, here by rotating a gear shift axle Ila arranged concentrically inside the input shaft 10a.

[0080] The crank shaft 3 provides input torque to the gear input shaft 10a via a crank drive 40, comprising crank wheel 41 arranged concentrically about the crankshaft 3, first gear input wheel 42 concentrically fixed to the input shaft Ila and a crank chain 45 interconnecting the crank wheel 41 and the first gear input wheel 42. The first one-way clutch 31 allows the crank drive 40 to be driven by the crankshaft but freewheels in the other direction to prevent the crankshaft from being driven by the crank drive 40 in the case where the crank drive 40 is driven by a motor.

[0081] The output shaft 10b of the gear system 10 is concentrically fixed to a drive output element 72, driving a drive transfer element, 73 such as a belt or a chain, again driving a driven wheel.

[0082] The pedally propelled vehicle drive 1 further comprises a torque controller 700, configured to re-direct at least some of the torque from the crankshaft 3 to a torque sink before a gear shift in the gear system 10 takes place.

[0083] Optionally, the pedally propelled vehicle drive 1 comprises an assist motor 20 with a motor shaft 20a arranged to drive the crank wheel 41 of the crank drive 40 via a second one-way clutch 21. The second one-way clutch allows the crank drive 40 to be driven by the crankshaft but freewheels in the other direction to prevent the motor shaft 20a from being driven by the crankshaft 3.

[0084] Since the intention of the torque controller is to offload torque from the gear system, while at the same time retaining the riders cadence and input torque, the torque that is re-directed to the torque sink is adjustable and will vary with e.g., the current crank torque. In general the torque that should be redirected before a gear shift is at least the difference between the current crank torque and the maximum torque allowable for shifting gear in the gear system 10. The maximum torque is also called gear shift threshold or transmission shift threshold TST.

[0085] Fig. lb illustrates in more detail an embodiment of the torque controller 700 that could optionally be used in the previous embodiment above.

[0086] In this case the torque controller comprises a crank brake 80 and a brake actuator 84. The crank brake 80 is in normal operation not actuated, and all the torque from the crankshaft 3 is used to drive the crank drive 40 and the gear input shaft Ila. When the crank brake 80 is actuated by operating the brake actuator 84, some of the torque is directed away from the crank drive 40 and into the crank brake where the rotational energy is converted to heat. The elements that are heated, such as the housing and its internal components can therefore be seen as a torque sink in this context.

[0087] An optional third one-way clutch 71 is arranged between the brake hub 83 and the crankshaft 3. This allows backwards free rotation of the crankshaft when the crank brake is locked or partly locked.

[0088] The torque controller 70 does not necessarily have to be directly connected to the crankshaft, as long as it is able to redirect the torque from the crankshaft 3 away from the gear input shaft 10a.

[0089] While Fig. la shows the optional motor 20 driving the gear input shaft 10a of the gear system 10, Fig. 2 shows an alternative embodiment, wherein the motor 20 drives the gear output shaft 10. The second one way clutch 21 is here arranged between a gear driven by the motor and the gear output shaft 10b. The figure shows a gear train for torque transfer from the motor 20 to the output shaft, but this could also be achieved in the form of a chain, a belt etc.

[0090] Fig. 3a shows an alternative embodiment of a pedally propelled vehicle drive system 1 where the torque controller 70 is connected via a torque controller input wheel 43 to the crank drive 40 via the crank chain 45. The crank drive is here driven by the crank wheel 41 fixed to the crankshaft 3. The side view of Fig. 15 illustrates an advantageous and compact configuration of the crank drive.

[0091] As in the embodiment above, the crank shaft 3 provides input torque to the gear input shaft 10a via the crank drive 40. However, here the crank wheel is concentrically fixed to the crankshaft 3, while the first one way brake 31 is arranged between the first gear input wheel 42 and the gear input shaft 10a. This means that all the elements of the crank drive 40, including the torque controller input wheel 43 are rotationally fixed to the crankshaft 3. Thus, as above, the torque controller 70 connected to the torque controller input wheel 43 will be able to re-direct at least some of the torque from the crankshaft 3 to a torque sink before a gear shift in the gear system 10 takes place.

[0092] Optionally, the pedally propelled vehicle drive 1 comprises an assist motor 20 with a motor shaft 20a arranged to drive the crank wheel 41 of the crank drive 40 via a motordrive 60 comprising a motor wheel 41 concentrically fixed to the motor shaft 20a, a second gear input wheel 62 concentrically connected to the gear input shaft 10a via the second one way brake 21, and a motor chain 65 interconnecting the motor wheel 41 and the second gear input wheel 62.

[0093] The second one-way clutch prevents the motor drive 60 and the motor shaft 20a from being driven by the crankshaft 3.

[0094] Fig. 3b illustrates in more detail an embodiment of the torque controller 70 that could optionally be used in the embodiment above.

[0095] The torque controller comprises a crank brake 80 and a brake actuator 84. The overall working principle is as for the previous embodiment of the crank brake, but here the torque from the crankshaft 3, is available on the crank wheel 41. Further, since the torque controller in this embodiment is not concentric about the crankshaft 3, some of the internal elements, such as the brake actuator 84 can be simplified.

[0096] An optional third one-way clutch 71 is arranged between the brake hub 83 and the crank wheel 41. This allows backwards free rotation of the crankshaft when the crank brake is locked or partly locked.

[0097] Fig. 4 is identical to Fig. 3a, with the exception that the optional motor 20, wherein the motor 20 drives the gear output shaft 10. The second one way clutch 21 is here arranged between a gear driven by the motor and the gear output shaft 10b. The figure shows a chain drive for torque transfer from the motor 20 to the output shaft, but this could also be achieved in the form of a gear train, a belt etc.

[0098] In the embodiments above, two different arrangements of the motor 20 has been illustrated. In Fig. la, the motor is arranged concentrically about the crankshaft 3 where the crankshaft is allowed to rotate inside the motor 20 and inside the motor shaft 20a. In Fig. 3a the motor is arranged separately from the crank shaft 3. These arrangements could also optionally be interchanged, e.g. arranging the motor 20 separately from the crankshaft 3 in the embodiment in Fig. la by one-way rotationally fixing a motor wheel to the motor shaft 20a and driving the crank drive 70 with the motor wheel directly.Alternatively, the motor 20 and motor wheel 61 illustrated in Fig. 3a could be replaced with a motor and motor wheel arranged concentrically about the crankshaft 3. The motor, motor shaft and motor wheel would then have to provide room for the crankshaft to rotate internally.

[0099] In principle the separate motor drive 60 in Fig. 3a could be omitted with rearrangement of the first and second one-way clutches and allowing the motor to drive thecrank drive directly. However, as will be described later, the advantage of allowing the motor 20 to drive the gear input shaft 20a, independently of the crank drive 70, is that the motor can be used to compensate for the re-directed torque until the actual gear switch takes place. This is also referred to as "torque fill".

[0100] Fig. 5 illustrates in a block diagram torque and control flow of an embodiment a pedally propelled vehicle drive system. From the left we see that the crankshaft 3 transfers torque to the crank brake 80 via an optional third one-way clutch 71. When the crank brake 80 is not actuated by the actuator 84, the torque is transferred to the gear system 10 and further from the gear system 10 to the driven wheel 54. The motor 20 can transfer motor torque to the gear system 10 via the second one-way clutch 21. If the crank brake 80 is activated, little or no torque from the crankshaft will reach the first one-way clutch and the gear system 10. However, with the current configuration, the motor 20 can provide torque independently of the position of the crank brake 80 via one of the dashed lines, either to the input or the output of the gear system 10. This can be used for torquefill before and after the gear switch.

[0101] A control system 100 is responsible for timing of the operations for the gear shift to take place. The control system receives torque and speed data for the crankshaft from a crankshaft torque sensor and a crankshaft rotational speed sensor. Further, torque and speed data for the motor shaft may be derived from the control signal from the control signal to the motor 20. Further, actuation position data for the crank brake 84 and gear position data for the gear shift actuator can be obtained either derived from the actuation control signals themselves, or from actuator position sensors. Summarized, we see that the control system can control torques for the crank brake and the motor shaft, as well as controlling the gear shift. The torque values can be set based on available torque values from the crankshaft, the motor shaft, and the crank brake, as well as the current gear position. In addition, input from a gear shift operator could be used if the gear shifts are manually operated.

[0102] The optional third one-way clutch mentioned above allows backwards free rotation of the crankshaft 3 with activated crank brake 80.

[0103] An alternative embodiment to the one shown in Fig. 5 is shown in Fig. 6. The difference is that the crank brake 80 is arranged after the first and second one-way clutches 31, 21. While torque fill is possible in Fig. 5, it is only possible in the case where the motor 20 provides torque to the output of the gear system 10 as seen by the dashed line to the right. In the case where the motor provides torque through the crank brake 80,illustrated by the dashed line to the left, torque fill is not possible, since the motor torque cannot pass the crank brake 80 when the brake is activated.

[0104] Fig. 7 illustrates a typical downshift sequence with torque fill to achieve higher cadence and / or lower crankshaft torque for the case where the motor 20 is connected to the gear input shaft. Due to the number of torque lines, the figure has been split up into Fig. 8a,b,c,d,e and f for improved illustration.

[0105] In the figure the following lines representing torque during a gear shift are present:Tl: Gear input shaft 10a torqueT2: Gear output shaft 10b torque. The dashed part is the desired output torque, while the solid line is the actual output torque. Thus, the area between the dashed line and the solid line in Fig. 8d is the torque loss during the gear shift sequence.T3: Rider input torqueT4: Contribution from rider to gear input shaft 10a torqueT5: Motor torque.T6: Crank brake 80 torqueC: Cadence, i.e. pedal rotational speed

[0106] In the figures, time passes from left to right and the complete gear shift can be seen as comprising three main sequential phases referred to as pre-shift A, gear shift B and post shift C. Each of the phases may comprise one or more steps as indicated by the vertical lines.

[0107] The length of pre-shift A phase is primarily given by controller delays and behaviour of the components involved, such as e.g. the actuating time of the crank brake and the energy loading time of the gear shift actuator in case such actuator is used. The time may be adjusted for improved gear shift comfort / and or performance.

[0108] The post-shift C phase helps to avoid shocks to the driveline and improve shifting. The time may be adjusted for improved gear shift comfort / and or performance.

[0109] Optionally one or both of the pre-shift A and post-shift C phases may be adjusted in the control system 100 according to e.g. a sport vs. a comfort program as well as for semi- or full automatic shifting.

[0110] The pre-shift A, may comprise the following steps; initiating the gear shift SI, energizing the shift actuator S2, if needed, and starting friction brake actuation S3. A more detailed description of each of them follows below.

[0111] Initiating the gear shift sequence SI: This is the first indication available to the control system 100 that a gear shift should be performed. Such indication may be e.g., the result of an automatic shift control circuit, a shift signal from a shift operator etc. The signal will indicate upshift or downshift and optionally the number of gear steps to perform.

[0112] Energizing the shift actuator S2: In the case where the shift actuator 84 needs pre-loading, the pre-loading could start here.

[0113] Starting friction brake actuation S3: This is where actuation of the crank brake starts. If torque-fill from the motor is available, the motor could be controlled to compensate for the torque redirected by the crank brake.

[0114] The gear shift B phase can start when a sufficient amount of the torque from the crankshaft has been redirected to the crank brake. A sufficient amount means that the remaining torque contribution from the crankshaft alone is below the transmission shift threshold TST.

[0115] This phase comprises the following steps:

[0116] Gear shifting started S4: This can be defined as the point in time where the control system 100 sends a gear shift signal to the gear shift actuator 11 and the gear shift actuator has confirmed that the gear shift has actually started.

[0117] At this point in time the control system 100 will cut the motor torque. This results in a torque drop on the gear input shaft Ila, and the resulting torque on the gear input shaft Ila is below the transmission shift threshold TST. The shift actuator will then be able to switch gear as intended.

[0118] The transmission shift threshold TST is given my mechanical constraints inside the gear system 10, and the actual value will depend on the construction of the gear system 10 and the gear shift actuator 11. If a high torque is present across the clutches inside the gear system, the actuator will not be able to release or engage the clutches. Given that the gear shift actuator remains actuated already from a point in time where the torque across the clutches is high and the torque across the clutches then drops, the actuator torque will be sufficient to perform the switch when the torque drops below the transmission shift threshold TST. This means that the shift in this case occurs when the motor torque drops and not when the actuator is actuated.

[0119] At the moment when the transmission input torque T1 drops below the Transmission shift Threshold TST, the clutches inside the gear system are released, resulting in zero torque across the gear system. As soon as the clutches start to reengage, they will need a certain re-engagement or synchronization time before they are fully engaged. This is illustrated in Fig. 8b as a short horizontal line below the Transmission shift Threshold TST.

[0120] Gear shift completed S5: The gear shift actuation is completed when the gear ratio of the gear system has shifted. This may be determined by e.g. monitoring a position sensor of the gear actuator. If the gear actuator comprises a rotatable shift axle, the rotational position of the shift axle may indicate the gear ratio in use.

[0121] When the gear shift is detected, the brake is released, and brake torque will gradually be decreased until all the torque from the rider is directed to the gear input shaft 10a. However, the brake torque decrease is a relatively slow process, so the motor speeds up at the same time to fill up torque on the gear input shaft 10a. After reaching a top, the motor torque will gradually be reduced since less torque fill is needed.

[0122] Gear shift sequence completed S6: When all the torque from the rider has been redirected to the gear input shaft, the gear shift sequence is completed. Since this illustrated a downshift, the rider input torque T3 on the crankshaft is lower than before the gearshift. Further, the cadence C has increased.

[0123] Fig. 9 and 10 illustrates in an embodiment more details of a torque controller 70 that could optionally be applied in the pedally propelled vehicle drive system 1 shown in Fig. 3a and 4.

[0124] The torque controller 70 comprises a crank brake 80 in the form of a friction brake with disks, as well as a brake actuator 84. The torque controller input wheel 43 is used to link the brake to the crankshaft as shown previously.

[0125] Fig. 10 is an exploded view of the torque controller in Fig. 9. The torque controller input wheel 43 is integrated with a brake hub 83 connected to the first brake elements, while the second brake elements are connected to the brake basked 85. Thus, when the brake is not actuated, there is no friction between the first and second brake elements, resulting in a free rotation of the torque controller input wheel 43 with regards to the brake basket, or brake housing, 85 that is fixedly attached to a housing of the pedally propelled vehicle drive system. When the brake is actuated, there will be frictional engagement between the first and second brake elements, which will require a certain torque to overcome the friction force. Thus, the crankshaft 3 driving the torque controller inputwheel 43 will be harder to rotate. The frictional force depends on the actuation force of the actuator 84.

[0126] The crank brake is a multi-plate friction brake with a brake assembly comprising alternating steel plates 81 and friction plates 82. The steel plates have teeth along the circumference that are interlocked with slits 86 in a brake basket 85, while the friction plates have inner teeth interlocked with corresponding grooves 87 on the brake hub 83. The steel plates and the friction plates can slide along the slits and grooves in the direction perpendicular to the plates. A brake separation spring 88 is arranged between the steel plates and the friction plates to reduce drag when the brake is open or disengaged.

[0127] A pressure plate 184 is arranged on top of the brake pack consisting of the steel plates 81 and the friction plates 82. When the pressure plate is forced against the brake pack, friction will increase between the plates and the brake hub 83 will be locked to the brake basket 85.

[0128] The pressure on the pressure plate 184 is in this embodiment provided by a brake lever 193 connected to a brake actuator servo 191 with an actuator shaft 192. Here the actuator servo is an electrically powered linear actuator with a lead screw connected to a corresponding nut on the brake lever 193.

[0129] Fig. 11 and Fig. 12 illustrate in section views the crank brake in disengaged and engaged states, respectively.

[0130] The pressure on the pressure plate 184 is in this embodiment provided by a brake lever 193 connected to a brake actuator servo 191 with an actuator shaft 192.

[0131] The brake lever comprises first and second lever elements 194, 195 that are linked together by a moving lever pivot 196.

[0132] The first lever element 194 has the shape of an L where the long leg is connected to the actuator shaft 192 and the short end is abutting the pressure plate in a first recess 185. Further, the moving lever pivot 196 is arranged where the two legs meet and the second lever element 195 with a pyriform shape is pivotally connected to the lever pivot such that the two lever elements can pivot with regards to each other. The tapered end of the second lever element 195 abuts a second recess 186 of a spring support plate 181 arranged inside the brake basket 85, opposite the brake pack with regards to the brake lever 193. The first and second recesses 185, 186 ensures that the brake lever do not slide on the pressure plate and the spring support plate during operation.

[0133] In disengaged state, the lever pivot 196 is arranged to the side of an axis c through the first and second recesses as illustrated in Fig. 11. This could be the center line of the brake 80.

[0134] In the engaged state, the lever pivot 196 has moved to the axis c, as seen in Fig.12. This means that the effective width of the brake lever has increased in the c direction, and the pressure plate 184 has been forced towards the spring support plate 181 and the brake pack and that the friction between the brake plates has increased. In this position the brake engagement forces go directly through the lever pivot. Thus, little or no force is needed to keep the brake engaged. This is beneficial if the brake should be used e.g. as part of an immobilizer system.

[0135] As a precautionary measure, the brake has in one embodiment a torque limiter comprising a pre-loaded disk spring 182 outside the spring support plate 181. When the axial engagement force from the brake lever reaches the counterforce of the preloaded disk spring, the disk spring will start to compress to prevent damage to the brake or other components in the system.

[0136] Upper and lower retaining rings 187, 188 arranged in circumferential slits in the brake basket 85 are used to secure the disk spring and the spring support plate in the axial direction of the brake basket 85.

[0137] Fig. 13 and 14 illustrate in an embodiment more details of a torque controller 700 that could optionally be applied in the pedally propelled vehicle drive system 1 shown in Fig. la and lb where the torque controller is arranged concentric about the crankshaft 3.

[0138] As seen in Fig. 13, the torque controller 700 comprises a crank brake 80 in the form of a friction brake with disks inside a brake basket 85. A brake actuator 84 can actuate the crank brake. The crank wheel 41 is arranged about the crankshaft 3 via a second one-way clutch 21, allowing the crankshaft to drive the crank wheel in one direction and freewheel in the other.

[0139] Fig. 14 is a partly exploded view of the torque controller 700 where the brake basket has been removed for illustration and the brake plate assembly and some of the actuator elements have been moved to the right. Since the crankshaft extends through the brake, the brake lever 793 has the form of a fork, where the two fork arms extend on respective sides of the crankshaft 3. Further, the fork arms have first and second lever pivots 796a, 796b interconnecting second lever elements and the fork arms. The engagement and disengagement of the crank brake 800 work basically in the same way as for the crank brake 80 in the embodiment shown in Fig. 11 and 12, with the difference thatthe forked brake lever 193 abuts the spring support plate 781 and the pressure plate 784 on each side of the crankshaft instead of in the center.

[0140] To allow room for the concentric crankshaft, the spring support plate 781, the disk spring 782 and the pressure plate 784 all have a center through hole.

[0141] Optionally, a third one-way clutch 71 can be arranged as seen in Fig. 14, where the outer part of the third one-way clutch is connected to the brake hub 83, and the inner part of the one-way clutch is connected to the crankshaft 3. This allows backwards free rotation of the crankshaft when the crank brake is locked or partly locked.In the exemplary embodiments, various features and details are shown in combination. The fact that several features are described with respect to a particular example should not be construed as implying that those features by necessity have to be included together in all embodiments of the invention. Conversely, features that are described with reference to different embodiments should not be construed as mutually exclusive. As those with skill in the art will readily understand, embodiments that incorporate any subset of features described herein and that are not expressly interdependent have been contemplated by the inventor and are part of the intended disclosure. However, explicit description of all such embodiments would not contribute to the understanding of the principles of the invention, and consequently some permutations of features have been omitted for the sake of simplicity or brevity.

Claims

1. CLAIMS1. A pedally propelled vehicle drive system (1) comprising;- a crankshaft (3) configured to be rotatably driven by a rider's pedaling input,- a gear system (10) with multiple selectable gear ratios, wherein the gear system has a gear input shaft (10a) and a gear output shaft (10b), and is configured to provide an output torque in an output torque direction on the gear output shaft (10b) when an input torque in an input torque direction is present on the gear input shaft (10a),- a torque controller (70, 700) driven by the crankshaft (3), wherein the torque controller is configured to selectively alter the first torque by temporarily preventing at least a portion of the first torque from reaching the gear input shaft (10a) during a gear shift sequence.

2. The pedally propelled vehicle drive system 1 of claim 1, wherein the torque controller (70, 700) comprises a crank brake 80, configured to at least partly prevent rotation of the crankshaft (3).

3. The pedally propelled vehicle drive system 1 of claim 2, wherein the crank brake 80 is a friction brake, wherein at least some of the first torque is converted to thermal energy.

4. The pedally propelled vehicle drive system 1 of claim 2 or 3, wherein the crank brake 80 is a multi-plate brake.

5. The pedally propelled vehicle drive system 1 of any of claim 2 to 4, wherein the crank brake comprises alternating steel and friction plates 81, 82 arranged inside a brake basket 85.

6. The pedally propelled vehicle drive system 1 of any of claims 2 to 5, wherein the crank brake 80 is configured to provide a variable torque transfer from the crankshaft 3 to the torque sink.

7. The pedally propelled vehicle drive system 1 of any of claims 2 to 6, wherein the crank brake 80 comprises a brake actuator 84 configured to disconnect and connect the plates in the multi-plate brake.

8. The pedally propelled vehicle drive system 1 of any of claims 2 to 7, wherein the crank brake further comprises a resilient torque restrictor configured to restrict maximum torque from the lever arm 193 to the pressure plate 184.

9. The pedally propelled vehicle drive system 1 of any of claims 1 to claim 8, comprising a motor 20 configured to contribute with a second torque on the gear input shaft 10a, or the gear output shaft 10b..

10. The pedally propelled vehicle drive system 1 of claims 1 to 9, comprising a control system 100 configured to control the torque controller (70, 700).

11. A method for controlling a gear shift sequence in a pedally propelled vehicle drive system 1, comprising;- temporarily preventing at least a portion of a first torque from a crankshaft 3 from reaching a gear input shaft 10a of a gear system (10) with multiple selectable gear ratios, during the gear shift sequence.

12. The method according to claim 11, wherein the pedally propelled vehicle drive system 1 comprises;- a crankshaft (3) configured to be rotatably driven by a rider's pedaling input,- a gear system (10) with multiple selectable gear ratios, wherein the gear system has a gear input shaft (10a) and a gear output shaft (10b), and is configured to provide an output torque in an output torque direction on the gear output shaft (10b) when an input torque in an input torque direction is present on the gear input shaft (10a),- a torque controller (70, 700) driven by the crankshaft (3), wherein the torque controller is configured to selectively alter the first torque by temporarily preventing at least a portion of the first torque from reaching the gear input shaft (10a) during a gear shift sequence, wherein the method comprises;- monitor torque applied to the crankshaft (3),- detect an impending gear shift event in the gear system (10),- actuate the torque controller (70, 700) in response to the detected gear shift event to temporarily reduce the first torque transmitted to the gear input shaft (10a).

13. The method according to claim 12, comprising;- releasing the torque controller (70, 700) to increase the first torque transmitted to the gear input shaft (10a).

14. The method according to any of claim 11 to 13, wherein the pedally propelled vehicle drive system (1) comprises a motor 20 configured to contribute with a second torque on the gear input shaft 10a, wherein the total torque on the gear input shaft 10a is the sum of the first and second torques, wherein the method comprises;- increasing the second torque when the first torque decreases during a gear shift sequence to maintain a stable total torque on the gear input shaft 10a during an initial part of the gear shift sequence.

15. The method according to any of claim 11 to 14, comprising;- momentarily canceling or reducing the second torque contribution after the initial part of the gear shift sequence.16 The pedally propelled vehicle drive system 1 of any of claims 11 to 13, wherein the motor is configured to drive the gear input shaft 10a, the method comprising- increasing the second torque to reduce the torque required for shifting, and allow the gear shift to take place.17: The pedally propelled vehicle drive system 1 of any of claims 11 to 116, comprising providing a torque fill, such that torque on the driving wheel is maintained during the shift.

18. A control system (100) for a pedally propelled vehicle drive system (1), implementing the features of any of claims 11 to 17.

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