drive unit

Abstract

Drive unit (30) for a muscle-powered vehicle, wherein the drive unit (30) comprises a gearbox (10) with a drive shaft (32) to which a plurality of drive wheels (45-51) are fixed, and a countershaft (52, 60) to which a corresponding plurality of driven loose gears (53-59) are rotatably mounted, meshing with the drive wheels (45-51), wherein the transmission (10) has an output shaft (34) which is designed as a hollow shaft, wherein a transmission shaft in the form of the input shaft (32), the intermediate shaft (52, 60) or the output shaft (34) is connected or connectable to a motor shaft (22) of an electric machine (20) in order to couple a torque into the transmission (10), wherein the majority of drive wheels (45 - 51) with the loose wheels (53 - 59) form a first partial transmission (42), wherein the loose wheels (53-59) can be connected to the countershaft (52, 60) in a rotationally fixed manner by means of first switching means (61), wherein the electric machine (20) can be connected in one drive direction to the transmission shaft in the form of the drive shaft (32), the countershaft (52, 60) or the output shaft (34) via a spur gear set by means of a non-switchable freewheel (99), and wherein the spur gear set comprises a gear (24) fixed to a motor shaft (22) of the electric machine (2), an intermediate gear (40) engaging with it and a gear mounted on the transmission shaft in the form of the input shaft (32), the countershaft (52, 60) or the output shaft (34), which engages with the intermediate gear (40).

Description

[0001] The present invention relates to a drive unit for a muscle-powered vehicle and to a bicycle with this drive unit.

[0002] The present invention further relates to a bicycle with such a drive unit.

[0003] Such drive units are used to drive vehicles powered by muscle power and to increase or decrease the drive force accordingly.

[0004] DE 10 2008 064 514 A1 discloses a transmission unit for a muscle-powered vehicle, which comprises a through shaft connected to pedal cranks for driving the vehicle and a countershaft. Switchable idler gears are mounted on the countershaft and form a partial transmission with gears of the through shaft and with gears of an output shaft, the output shaft being arranged coaxially to the through shaft. Up to 18 gears can be achieved with such a transmission unit. A disadvantage of this transmission unit is that no auxiliary motor is provided to support the muscle drive. Further transmissions and drive units are known from US 2011 / 0 120 794 A1, EP 1 445 088 A2, DE 197 20 794 A1, JP 4 056 130 B2, and DE 93 16 748 U1.

[0005] It is also known to equip bicycles with auxiliary motors, which are arranged as hub motors in the area of ​​the front or rear wheel hub. Hub motors of this type are usually offered in combination with derailleur gears. In particular, rear hub motors are complicated to combine with hub gears because the motor takes up a lot of space. Disadvantages of hub motors include their heavy weight and unfavorable weight distribution, as the proportion of the bicycle's unsprung mass in the front or rear wheel increases. Since hub motors of this type are directly connected to the wheel, they must operate at low speeds. Slow-rotating electric motors, which deliver a relatively high torque, are usually very large, weigh up to 4.5 kg, and are low in efficiency. For reasons of weight and space, hub motors of this type are rather disadvantageous.

[0006] To counteract this disadvantage, such auxiliary motors are also installed as mid-drive motors in the bottom bracket area, where the power is transferred directly to the chain. The disadvantage of this is that the chain cannot be shifted from one sprocket to the other in the bottom bracket area, which limits the use of derailleur gears. However, when using rear cassettes or conventional hub gears in conjunction with such mid-drive motors, only a maximum of ten gears is possible.

[0007] Against this background, the object of the present invention is to provide a drive unit that combines muscle power and the drive power of an auxiliary motor and at the same time has a low weight with a usual high number of gears and a usual spread.

[0008] This task is solved in the drive unit mentioned at the beginning in that one of the transmission shafts is connected or connectable to a motor shaft of an electric machine in order to couple a torque into or out of the transmission.

[0009] This problem is further solved by a bicycle with such a drive unit.

[0010] In the most general form of the invention, a drive unit for a muscle-powered vehicle is provided with a first shaft on which a plurality of gears are mounted, and a second shaft on which a corresponding plurality of gears are mounted, one of the shafts being connected or connectable to a motor shaft of an electric machine.

[0011] The advantage of the invention is that the electric motor is connected or can be connected to one of the transmission shafts. Thus, electric traction can be introduced into the transmission in a compact design, eliminating the need for vulnerable attachments. By connecting the electric drive to a multi-stage transmission unit and connecting the electric drive to one of the transmission shafts, it can be combined with any derailleur or hub gear system, allowing any number of shiftable gears to be implemented.

[0012] The object of the present invention is thus completely achieved.

[0013] Preferably, a drive unit for a muscle-powered vehicle is provided, comprising a drive shaft connectable to a drive source for driving the vehicle, a countershaft on which a plurality of gears are mounted, and an output shaft, wherein the gears mounted on the countershaft each mesh with a gear mounted on the drive shaft or the output shaft, wherein one of the transmission shafts is connected or connectable to a motor shaft of an electric machine in order to couple a torque into or out of the transmission.

[0014] Preferably, the transmission shaft is the drive shaft.

[0015] This allows the electric motor to operate within a narrow speed range regardless of the driving speed, as the electric motor drives the input of the transmission and can therefore always operate close to the optimal operating point. This narrow operating range, in which the electric motor operates, allows for greater efficiency and a more compact design of the electric motor.

[0016] Alternatively, it is preferred if the transmission shaft is the countershaft.

[0017] This means that the transmitted engine power is transmitted via only one pair of gears, reducing friction losses. The gear ratio of the gear pair allows for the use of a high-speed, lightweight, and compact motor. Furthermore, the coupling of the electric motor to the countershaft enables recuperation, i.e., brake force recovery, when the vehicle is coasting.

[0018] Alternatively, it is preferred if the transmission shaft is the output shaft.

[0019] This prevents engine power from being reduced by friction losses in the transmission. Furthermore, recuperation is possible because the engine is connected to the output shaft, which rotates via the sprocket.

[0020] Preferably, a plurality of gears are mounted on the output shaft, forming a partial transmission with gears of the countershaft. The gears of the countershaft are designed as loose gears that can be connected to the countershaft in a rotationally fixed manner by means of switching means. This allows for the realization of a multi-stage partial transmission in a simple and compact design.

[0021] Preferably, a plurality of gears are mounted on the drive shaft, forming a partial transmission with gears of the countershaft. The gears are designed as loose gears that can be connected to the countershaft in a rotationally fixed manner by means of switching means. The fact that the second partial transmission is designed as a variable-speed transmission increases the total number of gears of the drive unit.

[0022] Preferably, the shifting means comprise switchable freewheels that can be actuated by a camshaft mounted in the countershaft, which is designed as a hollow shaft. This allows the corresponding sub-transmission to be implemented in a compact design as a powershift transmission.

[0023] Preferably, two camshafts are provided for shifting the two partial transmissions, with the second camshaft being actuated by the first camshaft mounted in the countershaft by means of a driver. This allows the transmission unit to be shifted conveniently using a single shift lever.

[0024] Preferably, the electric motor can be connected to the respective transmission shaft via a reduction gear. This allows the use of high-speed electric motors that require less space and are lighter than slow-speed electric motors.

[0025] It is further preferred if the electric machine can be connected to the respective transmission shaft by means of a clutch, in particular a clutch or a switchable freewheel. This allows the electric machine to be mechanically coupled to or decoupled from the transmission, so that the motor shaft of the electric machine does not need to be rotated in pure muscle-drive mode.

[0026] Furthermore, it is preferred if the reduction gear comprises at least one, preferably two or more planetary gears. This allows the reduction gear to be realized with a high reduction ratio in a compact design.

[0027] Furthermore, it is preferred if the motor shaft of the electric machine can be connected in a rotationally fixed manner to one of the gears of the transmission shafts. This allows for simple and compact coupling and decoupling of the torque, since an existing gear can be used.

[0028] It is further preferred if the motor shaft can be connected to the transmission shaft in a rotationally fixed manner, at least in one direction of rotation, by means of a ratchet wheel mounted on the transmission shaft. This allows the torque to be transmitted to the transmission shaft in a simple design.

[0029] It is preferred if the switching gear can be connected to the transmission shaft in a drive direction by means of a freewheel, in particular a switchable freewheel. This allows the electric motor to be connected to the transmission shaft in the drive direction and automatically switches to freewheeling mode as soon as the transmission shaft has a higher speed than the electric motor.

[0030] It is further preferred if the switching gear can be connected to the transmission shaft in a rotationally fixed manner by means of a switchable freewheel in a direction opposite to the drive direction. This allows switching from drive mode to recuperation mode using simple means.

[0031] Furthermore, it is preferred if the switchable freewheels can be actuated by means of a camshaft arranged in the transmission shaft. This allows the switchable freewheels of the shift gear to be switched in a simple and compact design, enabling easy switching from drive to recuperation mode.

[0032] It is preferred if the camshaft is rotatable relative to the transmission shaft for engaging the freewheels, wherein the camshaft is rotatable relative to the transmission shaft by means of a speed-superimposing gear, in particular by means of a second planetary gear. This allows for a particularly compact design in the axial direction.

[0033] In general, it is preferred if the motor shaft of the electric machine is arranged parallel to the transmission shafts. This allows the motor shaft of the electric machine to be connected in a simple manner to the corresponding shaft of the first or second partial transmission by means of an intermediate gear or a spur gear.

[0034] Alternatively, it is preferred if the shaft of the electric motor is arranged at a 90° angle to the transmission shafts. This allows the electric motor to be mounted in a tube of the bicycle frame, thus achieving a compact overall design.

[0035] It is preferred if the motor shaft of the electric machine can be connected to one of the transmission shafts by means of a crown gear or a bevel gear. This allows for a simple, angled arrangement of the motor shaft of the electric machine relative to one of the shafts of the sub-transmissions.

[0036] Overall, it is preferable for the shaft of the electric motor to be formed integrally with one of the transmission shafts. This allows for a particularly compact and lightweight design because the corresponding transmission shaft is used twice.

[0037] In general, it is preferable if, during the shifting process from one gear to the next, the shift pawls of the corresponding idler gears are initially pivoted radially outward simultaneously in an intermediate state. This allows for the realization of a powershift transmission, which simultaneously increases safety against spin of the pedal crank in the event of a shift pawl breakage.

[0038]

[0039] Embodiments of the invention are illustrated in the drawings and explained in more detail in the following description. They show: Fig. 1 a side view of a bicycle frame with a multi-speed transmission and an electric drive; Fig. 2a-c a schematic representation of an electrical machine and a coupling by means of a clutch and reduction gear; Fig. 3 a circuit diagram of a drive unit with multi-speed transmission and electric drive; Fig. 4 a circuit diagram of a drive unit with a multi-speed gearbox and an electric drive coupled to the drive shaft; Fig. 5 a circuit diagram of a drive unit with a multi-speed gearbox and an electric drive coupled to the drive shaft; Fig. 6 a circuit diagram of a drive unit with a multi-speed transmission and an electric drive coupled to the output shaft of the multi-speed transmission; Fig. 7 a circuit diagram of a drive unit with a multi-speed transmission and electric drive coupled to the output shaft of the multi-speed transmission; Fig. 8 shows a circuit diagram of a drive unit with a multi-speed gearbox and an electric drive coupled to the countershaft; Fig. 9 a circuit diagram of a drive unit with a multi-speed gearbox and an electric drive coupled to the countershaft; Fig. 10 shows a circuit diagram of a drive unit with a multi-speed transmission and an electric drive, in which the motor shaft of the electric drive is arranged orthogonally to the transmission shafts and is coupled to the countershaft via a crown gear; Fig. 11 shows a circuit diagram of a drive unit with a multi-speed transmission and an electric drive, in which the motor shaft of the electric drive is arranged orthogonally to the transmission shafts and is connected to the output shaft via a bevel gear; and Fig. 12 a schematic sectional view of a shaft with a loose wheel connectable in both directions of rotation in an axial direction.

[0039] In Fig. 1 shows a transmission unit for a muscle-powered vehicle and is generally designated 10.

[0040] Fig. Figure 1 shows a side view of a bicycle frame 12 having a transmission housing 14 in which the transmission unit 10 is housed. The transmission unit 10 is indicated schematically in this illustration and is designed as a compact unit, preferably arranged in a transmission cage (not shown here). The transmission unit 10 is described here as an example for use in a two-wheeled vehicle, although it is also possible to use it in other human-powered vehicles.

[0041] The transmission unit 10 and the transmission housing 14, together with the pedal cranks 16 and 16', form a multi-speed transmission 18. The bicycle frame 12 has an electric drive 20 connected to the multi-speed transmission 18 to propel the vehicle in addition to the drive via the pedal cranks 16, 16'. The electric drive 20 is connected to an electrical energy source 21, which supplies the electric drive 20 with electrical energy. The energy source 21 is preferably designed as an accumulator 21.

[0042] In the Fig. 2a to 2c, the electric drive 20 is shown schematically with different coupling options.

[0043] Fig. Figure 2a shows the electric drive 20, which has the motor shaft 22 connected to a gear 24. The gear 24 serves to transmit the torque generated by the electric drive 20, which is transmitted via the motor shaft 22 to the gear 24, to other gears of the transmission unit 10. Any electrical machine can be used as the electric drive 20, in particular DC motors with and without commutator sliding contacts.

[0044] In Fig. Figure 2b shows the electric drive 20 with a reduction gear 26. The gear 24 is connected to the motor shaft 22 via the reduction gear 26. The reduction gear 26 is formed by two planetary gears connected in series, with the motor shaft 22 being connected to a sun gear of the first planetary gear. As an output, a planet carrier of the first planetary gear is connected to a sun gear of the second planetary gear. The gear 24 is connected to a planet carrier of the second planetary gear. Ring gears of the planetary gears are mounted in a rotationally fixed manner or are fixed to the housing. This allows the speed of the electric drive 20 to be reduced using simple means, allowing the electric drive to be designed for a higher nominal speed range and significantly reducing the weight and size of the electric drive 20.

[0045] In Fig. Figure 2c shows the electric drive 20 with the reduction gear 26, wherein the shaft 22 has a clutch 28 for releasably connecting the electric drive 20 to the reduction gear 26. The clutch 28 can be designed as a switchable clutch or as a switchable freewheel, in particular as a sprag clutch, as an axial freewheel clutch with end-face toothing, as a ratchet freewheel, or as a switchable friction clutch.

[0046] The clutch 28 can be arranged at any point in the power flow between the electric drive 20 and the transmission unit 10. The arrangement between the electric drive 20 and the reduction stage 26 is advantageous because the applied torque is low and thus the clutch can be dimensioned smaller. However, the disadvantage here is that the transmission stage 26 is also rotated and accelerated during muscle power operation, which increases driving resistance. If the clutch 28 is arranged further back in the power flow between the electric drive 20 and the transmission unit 10, for example between an intermediate gear and a gear wheel of the transmission unit 10, fewer gears are rotated, which reduces driving resistance. In this case, however, the clutch 28 must transmit a greater torque and therefore must be dimensioned larger.Furthermore, electric bicycles may only be electrically powered up to a certain maximum speed, although it must be possible to travel faster using muscle power. For this purpose, the electric drive 20 must be decoupled from the transmission unit 10.

[0047] In principle, a distinction can be made between a low-speed concept and a high-speed concept for electric drives. With the low-speed concept, the rated speed range of the electric drive is approximately in the working range of the gearbox and can engage with the gearbox directly or via a low-reduction gear stage. Electric drives that operate in a low speed range and generate high torque are relatively large and heavy and sometimes have poor efficiency. The advantage of this concept, however, is that a complex reduction stage is not necessary to reduce the motor speed to a corresponding gearbox speed. In the event that the electric drive 20 is to be operated as a generator for energy recovery, only the flywheel mass of the motor needs to be accelerated and not the flywheel mass of the reduction stage.

[0048] With the high-speed concept, the rated speed range is significantly higher than the speed range of the gearbox. These motors are relatively small and lightweight with a high power density, which contributes to a compact design of the entire drive unit. The high motor speed must be reduced to the speed range of the gearbox by the reduction gear 26. With a multi-stage planetary gear, as shown at 26, a reduction ratio of 25 is feasible. The disadvantage of this design, in addition to the complex transmission stage, is the behavior in generator mode, which is relatively sluggish and can even lead to self-locking. With high transmission ratios of the reduction unit 26, the electric drive 20 cannot rotate due to the motor resistance and the friction of the reduction stage 26. A further disadvantage of fast-rotating motors and gear stages is increased noise generation.

[0049] In Fig. 3 shows a drive unit for driving a vehicle and is generally designated 30.

[0050] The drive unit 30 comprises the gear unit 10 and the electric drive 20.

[0051] The transmission unit 10 has a drive shaft 32 and an output shaft 34. The drive shaft 32 is designed as a through shaft and forms the input shaft 32 of the transmission unit 10. The output shaft 34 is designed as a hollow shaft. The drive shaft 32 and the output shaft 34 are arranged coaxially with each other. The output shaft 34 is rotationally fixedly connected to a chainring 36, which forms an output member of the transmission unit 10. The drive shaft 32 can be connected on opposite sides to the pedal cranks 16, 16' in order to drive the drive shaft 32.

[0052] A first gear 38 is mounted on the drive shaft 32 and meshes with an intermediate gear 40. The intermediate gear 40 meshes with the gear 24, which is connected to the electric drive 20 via the motor shaft 22. The gear 24 is thus connected to the drive shaft 32 in a rotationally fixed manner via the intermediate gear 40 and the gear 38. As a result, the drive shaft 32 can be driven by the electric drive 20.

[0053] The transmission unit 10 has a first sub-transmission 42 and a second sub-transmission 44. A plurality of drive gears 46, 47, 48, 49, 50 are mounted on the drive shaft 32. The drive shaft 32 forms the input shaft of the first sub-transmission 42. The first sub-transmission 42 has a countershaft 52 on which driven gears 54, 55, 56, 57, 58 are mounted. The driven gears 54 to 58 are designed as idler gears.

[0054] The driven wheels 54 to 58 can be connected to the countershaft 52 by means of switching means 61. The driven wheels 54 to 58 and the drive wheels 46 to 50 form gear pairs that have different gear ratios, so that different gear stages can be realized by selectively connecting the driven wheels 54 to 58 to the countershaft 52.

[0055] The second sub-transmission 44 has an input shaft 60 and the output shaft 34. The input shaft 60 is formed integrally with the countershaft 52. In an alternative embodiment, the input shaft 60 can be formed separately from the countershaft 52 and can be rotationally connected to the countershaft 52 via a transmission.

[0056] A gear 62 is mounted on the input shaft 60. A gear 64 is mounted on the output shaft 35, which forms both the output shaft of the second partial transmission 44 and the output shaft of the transmission unit 10. The gears 62 and 64 form a constant gear set and connect the input shaft 60 to the output shaft 34 in a rotationally fixed manner. In one embodiment of the transmission unit 10, the second partial transmission 44 has a plurality of gear pairs that have different gear ratios. The gears that are mounted on the input shaft 60 are preferably designed as loose gears, so that different gear stages of the second partial transmission 44 can be realized by selectively connecting the gears to the input shaft 60. In a special embodiment, the first partial transmission 42 can be formed by a constant gear set.

[0057] The Fig. The transmission unit 10 shown in Figure 3 has five different gear stages, which can be realized by the gear pairs of the first partial transmission 42. Since the electric drive 20 can be connected to the drive shaft 32 in a rotationally fixed manner, the electric drive 20 drives the transmission unit 10 on the same drive shaft 32 as the cyclist via the pedal cranks 16, 16'. Because the electric drive 20 is connected to the drive shaft 32 in front of the transmission unit 10, the electric drive 20 can be operated independently of the driving speed in a narrow speed range with a speed of approximately 70-100 rpm. The electric drive 20 can thus always be operated close to the optimal operating point, thereby achieving improved efficiency and a compact design. In this embodiment, the motor shaft 22 of the electric drive 20 is arranged parallel to the transmission shafts 32, 34, 52, 60.As an alternative to the parallel offset arrangement of the electric drive 20, the electric drive 20 can also be arranged coaxially to the drive shaft 32, in particular between the gears 46 to 50, wherein the drive shaft 32 in this embodiment forms the motor shaft 22 and thus the rotor of the electric drive 20.

[0058] In a further embodiment, gear 24 can mesh directly with gear 38. Alternatively, intermediate gear 40 can also be designed as a traction mechanism or a chain. To achieve a desired center distance between motor axis 22 and the transmission shaft, a gear pairing consisting of gear 24 and intermediate gear 40 with a large pitch diameter can be used.

[0059] In Fig. Figure 4 shows an alternative embodiment of the drive unit 30. Identical elements are designated by identical reference numerals, with only the differences being explained here.

[0060] The drive gears 45 to 51 are mounted on the drive shaft 32, and the driven gears 53 to 59 are mounted on the countershaft 52. The drive gears 45 to 51 and the driven gears 53 to 59 form gear pairs that have different gear ratios. The driven gears 53 to 59 are designed as idler gears and can be connected to the countershaft 52 in a rotationally fixed manner by means of switching means 61. The countershaft 52 is designed as a hollow shaft in which a camshaft 66 is rotatably mounted. The camshaft 66 has different cams, by means of which the switching means 61 of the idler gears 53 to 59 can be actuated in order to selectively connect the idler gears 53 to 59 to the countershaft 52 in a rotationally fixed manner. The camshaft 66 is connected to the countershaft 52 via a speed superposition gear 68. The speed superposition gear 68 is arranged coaxially to the countershaft 52.The speed superposition gear is formed by a first planetary gear 70 and a second planetary gear 72. The first planetary gear 70 has a tension disk 74 connected to a ring gear of the planetary gear 70. The speed superposition gear 68 is designed to rotate the camshaft 66 synchronously with the countershaft 52 and to transmit a rotation of the tension disk 74 to the camshaft 66 as a relative movement of the camshaft 66 to the countershaft 52. As a result, the idler gears 53 to 59 can be connected to the countershaft 52 by the relative movement of the camshaft 66 to the countershaft 52, whereby different gears or transmission ratios can be selectively realized. The idler gears 53 to 59 can be connected in a rotationally fixed manner to the countershaft 52 in one drive direction by means of switchable freewheels 61.

[0061] The gear 24 is connected to the driven gear 59 via the intermediate gear 40 in a rotationally fixed manner. This allows the rotation of the electric drive 20 to be transmitted to the driven gear 59. If the driven gear 59 is not connected to the countershaft 52 in a rotationally fixed manner, the driven gear 59 drives the drive gear 51 of the drive shaft 32, so that torque is transmitted from the electric drive 20 to the drive shaft 32. This connects the electric drive to the drive shaft 32 and is connected upstream of the transmission unit 10. Electric traction can thus be transmitted to the drive shaft 32.

[0062] It is understood that the gear 24 can also mesh directly with the driven wheel 59. It is understood that the electric drive 20 can be arranged coaxially with the drive shaft 32. The drive shaft 32 can be integrally connected to the motor shaft 22 and form the rotor of the electric drive 20. The electric drive 20 can also be arranged between the drive wheels 45 to 51. Advantage of the Fig. The embodiment shown in Figure 4 is that the driven wheel 59 and the drive wheel 51 serve both to initiate the electric traction and as a gear pair of the first partial transmission. Furthermore, the torques of the electric drive 20 and the muscle drive overlap due to the rotationally fixed connection of the drive shaft 32 to the motor shaft 22.

[0063] The switchable freewheels 61 preferably have pawls that engage with internal toothings of the idler gears 53-59 to connect them in a rotationally fixed manner to the countershaft 52. The internal camshaft 66 moves the pawls inward to disengage them from the internal toothing. The pawls are preloaded by a spring that moves the pawls outward to engage the pawls with the internal toothing. When shifting, it is preferred if the pawls of two consecutive gear steps are pivoted radially outward simultaneously in an intermediate state. Since the higher gear step has a lower transmission ratio, the pawls of the higher gear engage with the toothing and drive the countershaft at a rotational speed that is greater than the rotational speed of the idler gear of the lower gear.The lower gear's pawl then shifts into freewheel mode, immediately engaging the higher gear. In a subsequent step, the lower gear's pawl is actuated, i.e., moved inward, to fully engage the higher gear. This allows for a powershift transmission, preventing a neutral condition and increasing driver safety.

[0064] Fig. Figure 5 shows a further embodiment of the drive unit 30, in which the electric drive 20 is connected upstream of the transmission unit 10. Reference is made to the Fig. 3 and Fig. 4, where like elements are designated by like reference numerals and only the differences are explained here.

[0065] The first sub-transmission 42 has the drive gears 45 to 50 and the driven gears 53 to 58, which form gear pairs with different gear ratios. The driven gears 53 to 58 are designed as idler gears and can be connected to the countershaft 52 by means of the switching means 61. The switching means 61 can be selectively actuated by means of the camshaft 66 arranged in the countershaft 52. The camshaft 66 is connected to the speed superposition gear 68 in order to rotate synchronously with the countershaft 52 and to be rotated relative to the countershaft 52 for switching from one gear stage to another.

[0066] The second sub-transmission 44 has the input shaft 60, on which drive gears 76, 78 are mounted. The drive gears 76, 78 mesh with driven gears 80, 82, which are mounted on the output shaft 34. The drive gears 76, 78 are designed as loose gears and can be connected in a rotationally fixed manner to the input shaft 60 by means of switching means 79. The meshing drive gears 76, 78 and driven gears 80, 82 form gear pairs with different gear ratios. The switching means 79, which connect the drive gears 76, 78 to the input shaft 60, can be selectively actuated by a camshaft 84 rotatably mounted in the input shaft 60. Different gear stages of the second sub-transmission 44 are realized by the selective connection of the drive gears 76, 78 to the input shaft 60.Because the first partial transmission 42 and the second partial transmission 44 are connected in series, the gear stages of the two partial transmissions 42, 44 are multiplied to a total number of gears of the transmission unit 10. In this case, twelve gear stages are realized.

[0067] The camshaft 84, like the camshaft 66, rotates synchronously with the input shaft 60 to maintain a set shifting state and is rotated relative to the input shaft 60 to change the shifting state of the second sub-transmission 44. The camshaft 84 is connected to the camshaft 66 via a driver 86. The driver 86 transmits a relative rotation to the camshaft 84 when the highest gear of the first sub-transmission 42 is reached in order to shift from the sixth gear, in this case, to the following seventh gear. In this case, the driver 86 rotates the camshaft 84 such that the first gear of the second sub-transmission 44 shifts into second gear. At the same time, the rotation of the camshaft 66 shifts the first sub-transmission 42 from sixth gear to first gear. This allows both partial transmissions 42, 44 to be switched by actuating the pulley 74 of the speed superposition gear 68.

[0068] The gear 24 of the electric drive 20 is connected in a rotationally fixed manner to the drive gear 45 via the intermediate gear 40. This allows electric traction to be introduced into the transmission unit 10 via the drive shaft 32. The advantage of this is that the drive gear 45 is both part of a gear pair of the first partial transmission 42 and serves to initiate the electric traction of the electric drive 20.

[0069] It is understood that the electric drive can also be arranged coaxially to the drive shaft 32, wherein preferably the motor shaft 22 is formed integrally with the drive shaft 32 and forms the rotor of the electric drive 20.

[0070] In general, when initiating electric traction via the input shaft during downshifting under load, the electric drive must be interrupted in order to improve shifting behavior.

[0071] In Fig. 6 shows the drive unit 30, in which the electric traction of the electric drive 20 is introduced into the transmission unit 10 via the output shaft 34. The transmission unit 10 in Fig. 6 is identical to the one in Fig. 5 illustrated gear unit 10. Identical elements are designated by the same reference numerals, with only the differences being shown here.

[0072] The gear 24 is connected in a rotationally fixed manner to the driven gear 78 via the intermediate gear 40. This creates a rotationally fixed connection between the electric drive 20 and the output shaft 34 via the intermediate gear 40 and the gear pair formed by the drive gear 78 and the driven gear 82. The drive gear 78 is connectable to the input shaft 60 via a switchable freewheel 79, so that the drive gear 78 slides on the input shaft 60, provided the rotation of the input shaft 60 is greater than that of the drive gear 78.

[0073] Initiating electric traction via the output shaft 34 is advantageous because the transmission unit 10 only has to transmit the rider's muscle power, thereby reducing the dimensions of the transmission in terms of durability and weight. Furthermore, recuperation operation is easily possible because the electric drive 20 is connected to the output shaft 34 and the rotation of the output shaft 34 is not translated by the transmission unit. However, a prerequisite for recuperation operation is that the chainring 36 is connected to the output shaft 34 in a rotationally fixed manner. Furthermore, it is necessary that no freewheel is implemented in the rear wheel, i.e., that the rear wheel is designed with a fixed gear.

[0074] Furthermore, the switching behavior of the transmission unit 10 is improved in this case, since the engine power is introduced in the power flow after the switchable freewheels 61, 79 and can therefore be switched without reducing the engine's power.

[0075] In Fig. 6, the electric drive 20 is arranged parallel to the transmission shafts. In a particular embodiment, the electric drive 20 can also be arranged coaxially with the output shaft 34. It is preferred if the motor shaft 22 forms part of the output shaft 34 and, in particular, is formed integrally therewith.

[0076] In Fig. 7 shows a further embodiment of the drive unit 30. The gear unit 10 essentially corresponds to the gear unit 10 shown in Fig. 6. Identical elements are designated by identical reference numerals, with only the differences being explained.

[0077] The intermediate gear 40 meshes with an idler gear 88, which is mounted on the input shaft 60 by means of a bearing 90. The idler gear 88 is connectable to the drive gear 78 via a clutch 92. The clutch 92 can be designed as a freewheel clutch or as a switchable clutch, which connects the idler gear 88 to the drive gear 78 in a rotationally fixed manner in one or both directions of rotation. As a result, as in the embodiment according to Fig. 6, the traction of the electric drive 20 is transmitted to the output shaft 34 via the drive gear 78 and the driven gear 82. The advantage of this embodiment is that the intermediate gear 40 and the gear 24 can be decoupled from the transmission unit 18, so that these gears do not rotate continuously during pure muscle operation. Furthermore, this embodiment eliminates the need for a separate clutch on or in the electric drive 20. The clutch 92 can be actuated, for example, via the camshaft 84 in the shaft 60.

[0078] In general, a disadvantage of this concept is that the electric drive 20 cannot be operated in a narrow speed range, but must cover the entire speed range.

[0079] The clutch 92 can generally be designed as a switchable clutch or switchable freewheel, in particular as a sprag freewheel, as an axial freewheel clutch with front-end toothing, as a ratchet freewheel or as a switchable friction clutch.

[0080] In Fig. 8 shows the drive unit 30, in which the electric traction is introduced via the countershaft 52 or the input shaft 60 of the second partial transmission 44. The transmission unit 10 essentially corresponds to the transmission unit from Fig. 5 and Fig. 6. Identical elements are designated by the same reference numerals, only the differences being shown here.

[0081] A freewheel 94 is mounted on the input shaft 60 of the second sub-transmission 44. The freewheel 94 locks with the input shaft 60 in one drive direction of the electric drive 20 and slides on the input shaft 60 in an opposite direction of rotation. As a result, the electrical traction of the electric drive 20 is transmitted from the gear 24 via the intermediate gear 40 and the freewheel 94 to the countershaft 52 or the input shaft 60. If the input shaft 60 rotates faster than the freewheel 94, the freewheel 94 slides on the input shaft 60 or the input shaft 60 slides under the freewheel 94. The electric drive 20 is thus connected downstream of the freewheels 61 of the first sub-transmission 42 and upstream of the freewheels 79 of the second sub-transmission 44.As a result, the drive force of the electric drive 20 is advantageously not transmitted through the first partial transmission 42, but only through the second partial transmission 44, as a result of which the first partial transmission 42 can be dimensioned correspondingly smaller. Because the electric drive 20 is connected upstream of the second partial transmission 44, the speed range of the electric drive 20 can be dimensioned correspondingly narrower, as a result of which the design of the electric drive 20 can be smaller and lighter. In general, it is preferred if the traction of the electric drive 20 is introduced onto the countershaft 52 or the input shaft 60 in the axial direction as close as possible to the second partial transmission 44. It is particularly preferred if the traction of the electric drive is introduced onto the input shaft 60 at an axial end of the input shaft 60, specifically on a side opposite the countershaft 52.This reduces the torsional load on the countershaft 52 or the input shaft 60, which leads to a longer service life of the shaft.

[0082] During recuperation, energy is recovered when the vehicle is braking, which can be used to charge the accumulator 21 or a battery in order to increase the vehicle's range. For this purpose, a separate generator can be integrated into the system. This generator is installed in the drive unit 30 or is arranged on the vehicle as an external component and can be switched on separately, similar to a dynamo. It is generally possible to use the electric drive 20 as a generator during the vehicle's braking phases. However, this is only possible if the electric drive 20 is coupled downstream of the freewheels of the second partial transmission 44, since these do not allow the electric drive 20 to rotate during the coasting or braking phases, but instead switch to freewheeling.Such recuperation by means of the electric drive 20 is thus possible if the motor shaft 22 is connected in a rotationally fixed manner to the output shaft 34 or if the motor shaft 22 can be connected in a rotationally fixed manner to the input shaft 60 or the countershaft 52 and the second partial transmission 44 is designed as a constant gear set. Furthermore, for recuperation operation, the output shaft 34 must be driven during coasting or braking, i.e., the bicycle must have a rigid or switchable rear wheel hub so that the chain or the output shaft 34 rotates during overrun.

[0083] As described above, the clutch 28 is preferably arranged between the electric drive 20 and the transmission unit 10 so that the vehicle can be driven purely by muscle power, without the engine rotating. In the case of recuperation, the clutch 28 must transmit the torque, i.e., the braking torque, in the opposite direction of rotation, so that a simple one-way clutch is unsuitable for recuperation operation. In one variant of the drive unit 30, the clutch 28 is therefore designed as a switchable clutch that is engaged or rotationally fixed during the drive or braking phase of the engine and is disengaged during the muscle-powered operation phases.

[0084] For the freewheel 94 according to Fig. 8, recuperation is therefore not possible without further measures.

[0085] In Fig. Figure 9 schematically shows an embodiment of the drive unit 30 with a switchable freewheel. The transmission unit 10 is essentially identical to the transmission unit 10 of Fig. 8. Identical elements are designated by the same reference numerals, with only the differences being explained here.

[0086] A ratchet gear 96 is mounted on the input shaft 60 instead of the freewheel gear 94. The ratchet gear 96 is designed as a loose gear and can be connected to the input shaft 60 in a rotationally fixed manner by means of pawls 99. The pawls 99 are designed such that they connect the ratchet gear 96 to the input shaft 60 in a rotationally fixed manner in one direction and switch it to freewheeling in an opposite direction. The ratchet gear 96 has pawls 99, which in the drive direction connect the ratchet gear 96 to the input shaft 60 in a rotationally fixed manner, and further pawls 101, which in the opposite direction of rotation connect the ratchet gear 96 to the input shaft 60 in a rotationally fixed manner. The pawls 99, 101 can be selectively actuated by a camshaft 98.The camshaft 98 is connected to a speed superposition gear 100, which is designed to rotate the camshaft 98 synchronously with the input shaft 60 and, upon actuation of the speed superposition gear 100, to rotate relative to the input shaft 60. The relative rotation of the camshaft 98 selectively actuates the pawls 99, 101, so that the corresponding locking direction of the switching gear 96 can be changed. This allows either the switching pawls 99, 101 arranged in the first direction or those arranged in the opposite direction to be switched. Thus, switching can be made between a drive mode, in which traction is introduced from the electric drive 20 into the transmission unit 10, and a recuperation mode, in which torque is transferred to the electric drive 20 during overrun and accordingly converted into electrical energy.Alternatively, only the switching pawl 101 is actuated for recuperation by the camshaft 98, whereby the switching pawl 99 always remains pivoted out and, in drive mode, connects the input shaft 60 to the switching wheel 96 in a rotationally fixed manner and switches to freewheeling in recuperation mode.

[0087] The speed superposition gear 100 is structurally identical to the speed superposition gear 68. The speed superposition gear 100 has a first planetary gear 102, whose sun gear is connected to the camshaft 98 and whose ring gear is connected to a tension disk 104. The planet carrier of the planetary gear 102 is connected to a planet carrier of a second planetary gear 106, whose sun gear is connected to the input shaft 60 and whose ring gear is mounted fixedly to the housing.

[0088] By rotating the tension disc 104, the camshaft 98 rotates relative to the input shaft 60, so that the pawls 99, 101 of the switching gear 96 are switched. This allows the locking direction of the switching gear 96 to be reversed, allowing switching from the electric drive to the recuperation mode. The tension disc 104 is preferably actuated by means of a Bowden cable. In a preferred embodiment, the tension disc 104 is connected to a Bowden cable of the vehicle's braking system, so that the drive unit 30 is switched to the recuperation mode during each braking operation.

[0089] In an alternative embodiment, the speed superposition gear 100 can be connected to an actuator integrated into a control circuit of the vehicle. The actuator can be embodied as an electric motor connected to the externally toothed pulley 104. This allows automatic switching between driving mode and recuperation mode. The vehicle's control circuit preferably automatically detects whether the vehicle is in overrun mode. The speed superposition gear 100 can also be replaced by a corresponding actuator connected to both the input shaft 60 and the camshaft 98.

[0090] In an alternative embodiment, the switching wheel 96 can be mounted in an identical form on the output shaft 34.

[0091] When the electric traction is initiated via the countershaft 52 or the input shaft 60 of the second partial transmission 44, the electric drive is interrupted to shift the second partial transmission 44.

[0092] In Fig. 10 is an alternative embodiment of the drive unit 30 of Fig. 8 and Fig. 9, in which the motor shaft 22 of the electric drive 20 is arranged orthogonally to the gear shafts. The gear unit 10 is essentially identical to the gear unit of Fig. 8 and Fig. 9. Identical elements are designated by the same reference numerals, with only the differences being explained here.

[0093] Instead of the freewheel 94, the drive unit 30 is Fig. 10, a crown gear 108 is connected to the input shaft 60. The crown gear 108 is rotationally fixedly connected to the intermediate gear 40, which rotates about an axis orthogonal to the transmission shafts. The intermediate gear 40 is connected to the gear 24 of the electric drive 20, with the motor shaft 22 aligned orthogonally to the transmission shafts. Due to the orthogonal arrangement of the motor shaft 22, the electric drive 20 can be installed in a tube of the frame 12, whereby the electric drive 20 can be installed in the frame 12 in a space-saving manner. The crown gear 108 can be rotationally fixedly connected to the input shaft 60.

[0094] In a preferred embodiment, the crown gear 108 is connectable to the input shaft 60 by means of a one-way clutch. In a particularly preferred embodiment, the crown gear 108 is designed as a ratchet gear and is selectively connectable to the input shaft 60 in both directions of rotation, as is the case with respect to the ratchet gear 96. Fig. 9 is described in detail.

[0095] In Fig. 11 schematically shows a further embodiment of the drive unit 30, in which the motor shaft 22 is aligned orthogonally to the transmission shafts and the electrical traction is introduced into the transmission unit 10 via the output shaft 34. The transmission unit 10 is essentially identical to the one shown in Fig. 6 illustrated gear unit 30. Identical elements are designated by the same reference numerals, with only the differences being explained here.

[0096] The drive gear 76 of the second partial transmission 44 is connected to the motor shaft 22 in a rotationally fixed manner via a bevel gear pair 110. The bevel gear pair 110 comprises a bevel gear 112, which is connected to the motor shaft 22 in a rotationally fixed manner, and a bevel gear section 114, which is connected to the drive gear 76. The bevel gear pair 110 connects the drive gear 76 to the motor shaft 22, which is arranged orthogonally to the transmission shafts. As a result, as in the embodiment of Fig. 10 the electric drive 20 can be installed in a tube of the frame 12, e.g. in the down tube or in the seat tube.

[0097] In addition to the compact design of the bicycle, the electric drive 20 is protected from shocks and weather influences when housed in a frame tube and the appearance of the bicycle becomes more compact and sporty because the electric drive 20 is not visible from the outside.

[0098] In Fig. 12, the drive wheel 78 is shown in a schematic sectional view in the axial direction with the pawls 99, 101.

[0099] The drive gear 78 has internal teeth 116 into which the pawls 99, 101 can engage to connect the drive gear 78 to the input shaft 60 in a rotationally fixed manner in the corresponding direction of rotation. The pawl 99 is oriented such that it connects the drive gear 78 to the input shaft 60 in a rotationally fixed manner in the drive direction of the electric machine 20. The pawl 101 is oriented such that it connects the drive gear 78 to the input shaft 60 in a rotationally fixed manner in the opposite direction, the recuperation direction. The pawl 101 is pivotally mounted on the input shaft 60 and has an inner section 118 and an outer section 120. The inner section 118 can be actuated by the camshaft 98 in such a way that the outer section 120 engaging the internal toothing 116 is pivoted inwards in order to disengage the pawl 101 from the internal toothing 116.To engage the pawl 101 with the internal toothing 116, the camshaft 98 has a recess 122 into which the inner section 118 of the spring-loaded pawl 101 pivots inward. As a result, the outer section 120 pivots outward and engages the internal toothing 116, thereby connecting the input shaft 60 to the drive gear 78 in a rotationally fixed manner in the recuperation direction. In this embodiment, the pawl 99 for the drive direction is not actuated by the camshaft 98 and, during recuperation operation, runs in freewheeling fashion, connecting the drive gear 78 to the input shaft 60 in the drive direction in a rotationally fixed manner. Alternatively, the pawls 99, 101 can be actuated alternately by the camshaft 98 so that either the pawl 99 or the pawl 101 is pivoted out.

[0100] Through the Fig.12, switching to recuperation mode is possible by rotating the camshaft 98.

Claims

[1] Drive unit (30) for a muscle-powered vehicle, wherein the drive unit (30) comprises a transmission (10) with a drive shaft (32) to which a plurality of drive wheels (45-51) are fixed, and a countershaft (52, 60) on which a corresponding plurality of driven idler gears (53-59) are rotatably mounted, which mesh with the drive wheels (45-51), wherein the transmission (10) has an output shaft (34) which is designed as a hollow shaft, wherein a transmission shaft in the form of the drive shaft (32), the countershaft (52, 60) or the output shaft (34) is connected or connectable to a motor shaft (22) of an electric machine (20) in order to couple a torque into the transmission (10), wherein the plurality of drive wheels (45 - 51) together with the idler gears (53 - 59) form a first partial transmission (42), wherein the idler gears (53-59) are rotatably connected to the countershaft (52, 60) by means of first switching means (61), wherein the electric machine (20) is connectable in a drive direction to the transmission shaft in the form of the drive shaft (32), the countershaft (52, 60) or the output shaft (34) via a spur gear set by means of a non-switchable freewheel (99), and wherein the spur gear set has a gear (24) fixed to a motor shaft (22) of the electric machine (2), an intermediate gear (40) meshing therewith and a gear mounted on the transmission shaft in the form of the drive shaft (32), the countershaft (52, 60) or the output shaft (34), which gear meshes with the intermediate gear (40). [2] Drive unit according to claim 1, wherein at least one gear (62; 76, 78) is mounted on the countershaft (52, 60) and meshes with a gear (64; 80, 82) mounted on the output shaft (34). [3] Drive unit according to claim 2, wherein the transmission shaft is the countershaft (52, 60). [4] Drive unit according to claim 3, wherein the countershaft (60) forms an input shaft of a second partial transmission (44), on which a freewheel (94) is mounted, which is blocked with the countershaft (60) in a drive direction of the electric drive (20) and which slides on the countershaft (60) in an opposite direction of rotation. [5] Drive unit according to claim 4, wherein the electric machine (20) is connected downstream of freewheels of the first partial transmission (42) and upstream of freewheels of a second partial transmission (44), so that a driving force of the electric machine (20) is not transmitted through the first partial transmission (42). [6] Drive unit according to one of claims 2 to 5, wherein a plurality of gears (80, 82) are mounted on the output shaft (34), which gears form a second partial transmission (44) with gears (76, 78) of the countershaft (52, 60), wherein the gears (76, 78) of the countershaft (52, 60) are designed as loose wheels and can be connected to the countershaft (60) in a rotationally fixed manner by means of second switching means (79). [7] Drive unit according to claim 6, wherein the first and second switching means (61, 79) have switchable freewheels which can be actuated by means of a camshaft (66, 84) which is mounted in the countershaft (52, 60) designed as a hollow shaft. [8] Drive unit according to one of claims 1 to 7, wherein the electric machine (20) can be connected to the respective transmission shaft (32, 34, 52, 60) via a reduction gear (26). [9] Drive unit according to one of claims 1 to 8, wherein the motor shaft (22) of the electric machine (20) is rotatably connected to one of the gear wheels (45-51, 53-59, 62, 64, 76, 78, 80, 82) of the transmission shaft in the form of the drive shaft (32), the countershaft (52, 60) or the output shaft (34). [10] Drive unit according to one of claims 1 to 8, wherein the motor shaft (22) is rotatably connected to the transmission shaft in the form of the drive shaft (32), the countershaft (52,60) or the output shaft (34) by means of a switching wheel (94, 96) which is mounted on the drive shaft (32), the countershaft (52,60) or the output shaft (34), at least in one direction of rotation. [11] Drive unit according to claim 10, characterized by that the switching wheel (94, 96) can be connected to the transmission shaft (34, 62, 60) in a drive direction by means of a freewheel (99), in particular a switchable freewheel (99). [12] Drive unit according to one of claims 10 or 11, characterized by that the switching wheel (94, 96) can be connected in a rotationally fixed manner to the gear shaft (34, 52, 60) by means of a switchable freewheel (101) in a direction opposite to the drive direction. [13] Drive unit according to one of claims 11 or 12, characterized bythat the switchable freewheels (99, 101) can be actuated by means of a camshaft (98) arranged in the transmission shaft (34, 52, 60). [14] Drive unit according to claim 13, characterized by in that the camshaft (98) is rotatable relative to the transmission shaft (34, 52, 60) for switching the freewheels (99, 101), wherein the camshaft (98) is rotatable relative to the transmission shaft (34, 52, 60) by means of a speed superposition gear (100), in particular by means of two planetary gears (102, 106). [15] Drive unit according to one of claims 1 to 14, wherein the motor shaft (22) of the electric machine (20) is arranged parallel to the transmission shaft (32, 34, 52, 60). [16] Drive unit according to one of claims 1 to 14, wherein the motor shaft (22) of the electric machine (20) is arranged at an angle of 90° to the transmission shaft (32, 34, 52, 60). [17] Drive unit according to one of claims 1 to 14, wherein the motor shaft (22) of the electric machine (20) is formed integrally with the transmission shaft (32, 34, 52, 60). [18] Bicycle (12) with a drive unit (30) according to one of claims 1 to 17.

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