Wiring diagram for a bicycle

Description

[0001] The invention relates to a circuit arrangement for a bicycle, in particular an electric bicycle, and a bicycle, in particular an electric bicycle, with such a circuit arrangement.

[0002] Bicycles designed as e-bikes have an auxiliary motor that assists the cyclist's pedaling motion. Gears on both bicycles and e-bikes allow for pedaling at a relatively constant cadence across a wide speed range.

[0003] When tackling diverse tasks within the various environments where bicycles are used, a switchable gearbox is indispensable in most cases. While a single-speed bicycle, i.e., one with a fixed gear ratio, may suffice in flat urban traffic, its use reaches its limits over longer distances, such as those prevalent in rural areas.

[0004] Steep ascents or descents in mountain biking, heavy loads in passenger or goods transport, ergonomic aspects in long-distance rides, or ever-increasing maximum speeds require a variable gear ratio so that the rider can adapt the cadence and pedal force to the respective situation.

[0005] Currently, bicycles and e-bikes use hub gears, derailleur gears, and bottom bracket gears. In bicycles, these are usually implemented as pull-type gears, planetary gears, or spur gears. Planetary gears are typically found inside the rear wheel hub, while spur gears are often located near the bottom bracket axle. Pull-type gears primarily connect the bottom bracket axle to the rear wheel hub.

[0006] Over the past sixty years, the derailleur gear system, a chain drive with a shifter at the rear axle, has become widespread on bicycles. A rotating bottom bracket with one or more chainrings is mounted to the frame, which forms the load-bearing part of the bicycle and includes all its mounting points for the front fork, seat post, and rear wheel. A cassette consisting of various-sized sprockets is located on the rear wheel hub. A derailleur is attached to a dropout, which connects the frame to the rear axle. Its function is to guide the chain onto the sprockets of the cassette and enable gear changes. Additionally, a front derailleur, usually mounted on the seat tube at the bottom bracket, allows the rider to shift between different chainrings.Bicycles with a gear system as described above are generally referred to as bicycles with derailleur gears.

[0007] Because the components of a bicycle with a derailleur gear system are mounted externally on the frame, they are particularly exposed to environmental influences. This leads to increased wear, causing a significant decrease in efficiency after a short period of use. The resulting short maintenance intervals, especially on bicycles with auxiliary motors, become very costly due to the necessary replacement of the torque-transmitting components of the derailleur system. Furthermore, the front derailleur, due to its exposed position on the rear wheel, is easily damaged in crashes and on rough terrain.

[0008] In so-called "hub gears" and in gearboxes located in the bottom bracket area (hereinafter referred to as bottom bracket gearboxes), the components are arranged within a housing, protected from external influences. Hub gears usually feature simple or multiple planetary gear sets connected in series, which share the rear wheel's axis of rotation as the coaxial axis of rotation for the individual gear stages. Hub gears are often also called geared hubs.

[0009] Hub gears are essentially switchable planetary gears integrated into the hub housing of the rear wheel. They are encapsulated from the external environment within a housing and are therefore largely maintenance-free. However, a disadvantage of hub gears is their high weight at the rear wheel, which leads to an unfavorable weight distribution. This weight is bothersome not only when carrying the bicycle over obstacles, but also when cornering or riding off-road at a sporty pace. Another disadvantage of hub gears currently available on the market is the inability to shift under load. A cyclist pedaling uphill in a high gear with high torque and wanting to shift down a gear must first ease off the pedals to be able to shift into a lower gear with conventional hub gears.

[0010] In hub gear systems, the rider's torque is typically transmitted via a drive shaft to the input shaft, the so-called "driver," of the gear hub. From there, it is transformed by the planetary gears and transferred to the hub shell, which consequently serves as the output shaft of the transmission. The spokes attached to the hub shell connect the transmission to the rim, which, via the tire, transmits the torque to the road surface.

[0011] Bottom bracket gears offer a significantly more favorable weight distribution compared to the rear-heavy hub gears. However, bottom bracket gears are quite large, leaving no space around the bottom bracket for an electric motor. Furthermore, bottom bracket gears are already so heavy that the additional weight of an auxiliary drive would result in an e-bike that is too heavy for everyday use or for riding with a depleted battery. The shifting performance under load of bottom bracket gears is similarly poor to that of hub gears. Therefore, sporty use of a bicycle with bottom bracket or hub gears is hardly feasible.

[0012] Bottom bracket gearboxes typically feature spur gear drives, as described, for example, in DE 10 2009 060 484 B4, whose housings are attached to the main frame of the bicycle. This allows for a protected and compact installation space around the bottom bracket axle for the gearbox. The input shaft of a bottom bracket gearbox is usually directly connected to the cranks and pedals of the bicycle. A drive shaft on the output shaft transmits the torque to the rear wheel. This type of bicycle gearbox has the advantage that the weight of the gearbox is located at a central and low point, which has a positive effect on the center of gravity and thus on the handling characteristics.

[0013] In gear drives, the various gear ratios, hereinafter referred to as gears or gear stages, are achieved through different combinations of several gear pairs and their respective ratios. In spur and planetary gear drives, all gears of the input or intermediate shafts are usually constantly engaged with the corresponding gear of the following intermediate or output shaft. Consequently, at least one gear of another, currently inactive pair must always be able to rotate on its shaft without transmitting torque. Using switchable clutches, these free gears can be individually locked to the respective shaft or a subsequent component to transmit torque and shift gears. The activation of individual clutches, the shifting process, thus directs the torque through the gear pairs, which together produce the desired overall gear ratio of a gear.

[0014] The couplings are designed either as radial or axial couplings, mostly as positive-locking couplings, which predominantly transmit torque in only one direction of rotation, based on the principle of a freewheel. Fig. 9 and 10 The function of such a radial coupling can be clearly seen as an example in WO 1998 / 052817 A1.

[0015] Switchable axial couplings consist of one axially displaceable and one axially fixed component, as also described in WO 1998 / 052817 A1. Fig. 6 and 7 is shown.

[0016] The face-mounted toothing of an axial coupling offers the advantage of a significantly larger force-transmitting area within the same installation space compared to a radial coupling with pawls. This advantageously reduces the surface pressure.

[0017] The axial clutches are controlled, as illustrated, for example, in WO 1998 / 052817 A1, by a so-called actuating element, hereinafter also referred to as the shift shaft or shift drum. This is a cylindrical body with grooves, raised areas, and recesses. The shift drum is rotatably mounted in a fixed hollow shaft, hereinafter referred to as the main transmission shaft, with the angular position of the shift drum relative to the main transmission shaft defining the switching states (active, inactive) of the individual clutches for the gears. The angular position of the hollow shaft can be controlled by the rider from the bicycle handlebars, either mechanically via Bowden cables or electrically via an actuator.

[0018] WO 2019 / 192634 A1 discloses a multi-speed transmission mounted on a central axle with a drive-side hollow shaft and an output-side hub sleeve and with two coaxially arranged, at least two-stage planetary gear sets, each with sun gears, planet gears connected to each other via associated webs, and ring gears, each of which can be switched into a block rotation and several staged conversion modes, wherein the first planetary gear set is driven at its web and can be switched either into block rotation or into the aforementioned conversion modes by means of three clutches by means of axis fixing of individual sun gears, and the second planetary gear set can be switched into a conversion mode into a slow gear and a fast gear as well as into a direct gear by means of further clutches by means of axis fixing of the sun gear with alternating switching of the input and output between its ring gear or web.By means of axially displaceable control slides, coupling spring-loaded, radially extending clutch rings of a respective gear stage are released by means of the control slides being guided in helical circular grooves of a coaxial shift drum and in radial slots oriented parallel to the transmission axis of a hollow axle surrounding it, each actuating the associated clutch rings in a switching manner.

[0019] Considering a single axial clutch according to this state of the art, the two halves of the face gear teeth are usually held together by a single coil spring when engaged. To disengage an axial clutch, the axially displaceable clutch half is typically moved axially against the force of a spring by means of a sliding ring connected to the shift drum, so that the gear teeth are disengaged and the clutch is opened. Under load, certain functional surfaces of the movable clutch half are pressed against adjacent surfaces, generating high frictional forces. To shift from one gear to another under load, these frictional forces must be overcome. Since the frictional forces are very high in practice, shifting under load or partial load has so far been impossible or extremely difficult.

[0020] Therefore, there is a need for a circuit arrangement for a hub gear that is designed in such a way that a switching process under load is possible, or at least made easier.

[0021] This need is addressed by a gear arrangement for a bicycle, in particular for a hub gear, with a hollow main gear shaft that can be fixed rotationally fixed to a bicycle frame, with a driver rotatably mounted on the main gear shaft, with at least one planetary gear set having at least one gear component rotatably mounted on the main gear shaft in the form of a planet carrier or a sun gear, with a clutch having a clutch element axially displaceable relative to the main gear shaft between an engaged and a disengaged shift state, wherein the gear component is rotationally fixed to the main gear shaft in the engaged shift state of the clutch and is freely rotatable relative to the gear shaft in the disengaged shift state of the clutch; with an actuating element mounted in the gear shaft and rotatable relative to the main gear shaft.with at least one cam control connecting the actuating element to the axially displaceable clutch element and configured to convert a rotary movement of the actuating element into an axial displacement of the axially displaceable clutch element, with a housing-shaped sleeve in which the main transmission shaft and the at least one planetary gear set are received, with an actuator for rotating the actuating element, wherein the actuator is located outside the sleeve and has an electric motor, wherein the cam control has at least two switching fingers moved by a cam guide of the cam control and spaced apart from each other in the direction of rotation of the actuating element, which extend from the axially movable clutch element through an opening of the main transmission shaft into the cam guide, and wherein the clutch has an axially acting spring,which acts on the axially displaceable coupling element and the axially displaceable coupling element to the axially fixed coupling element of the coupling.

[0022] This need is also addressed by a bicycle, in particular a bicycle with an electric auxiliary motor, which has such a circuit arrangement.

[0023] The solutions described above prevent the axially displaceable clutch element from tilting during movement by the cam control. This significantly reduces friction during the shifting process, thus facilitating shifting under load.

[0024] The coupling has an axially acting spring that acts on the axially displaceable coupling element. In particular, the direction of action of this spring can be directed towards an engagement or closing movement of the coupling. In this configuration, the axially acting spring pushes the axially displaceable coupling element axially towards the stationary coupling element. In this way, the coupling is always closed in the unloaded state and is only opened by the action of the shift fingers. Alternatively or additionally, the axially acting spring can act on the shift fingers of the displaceable coupling element and preload them axially, so that, for example, the at least two shift fingers are always in contact with one side of a shift groove, particularly when the coupling is open, as described above.

[0025] The above solution can be further improved by the following independent and individually advantageous features. The features described below can be combined in any way.

[0026] The axially acting spring can comprise at least two parallel individual springs, preferably spaced apart from each other in the circumferential direction. This can ensure that the axially acting spring applies its spring force uniformly in the circumferential direction, thus preventing tilting.

[0027] In a first embodiment, the axial coupling element can be rigidly connected to the switching fingers. In particular, the switching fingers can be screwed or pressed into the axially movable coupling element. The switching fingers are preferably pin-shaped and, for example, cylindrical.

[0028] The at least two switching fingers can engage in a switching groove serving as a cam guide. The cam guide or switching groove can be formed in the surface of the actuating element and extend circumferentially around the actuating element. Alternatively, it can extend only over a portion of the circumference. The at least two switching fingers can be positively guided within the cam guide. Additionally or alternatively, an axial spring can be provided, which presses the at least two switching fingers against one side or flank of the cam guide during a switching operation. In such a configuration, the cam guide can be limited to the one side or flank against which the switching fingers are pressed by the switching spring.

[0029] The clutch can further comprise an axially stationary clutch element which, in the engaged switching state of the clutch, is engaged with the axially displaceable clutch element, wherein, in the disengaged switching state, the axially displaceable and the axially stationary clutch elements are separated from each other. The axially stationary clutch element can, in particular, be structurally integrated into or formed by the transmission component. The axially stationary clutch element can be rotatable relative to the main axis of the transmission.

[0030] The axially displaceable coupling element can, in particular, be mounted so as to be displaceable directly on the main axis of the transmission. The axially stationary coupling element can be mounted so as to be rotatable directly on the main axis of the transmission. The axially displaceable coupling element is preferably connected to the main axis of the transmission in a rotationally fixed manner when a sun gear is to be fixed relative to the frame by means of this coupling. In a further embodiment, the axially displaceable coupling element can be mounted so as to be displaceable axially on a torque-transmitting component. This torque-transmitting component is, for example, a hollow shaft through which the transmission component extends, or a shaft parallel to the main axis of the transmission.

[0031] To further reduce the risk of the clutch element moved by the shift finger tilting, it can be provided that two of the at least two shift fingers are diametrically opposed to each other with respect to a rotational axis of the actuating element. Alternatively or additionally, the longitudinal axes of the at least two shift fingers can intersect at a single point, which also reduces the risk of tilting.

[0032] Preferably, the axially acting spring is a wave spring. Such a wave spring can comprise a spring assembly of several leaf springs connected in parallel. Additionally, the axially acting spring can also be composed of several spring assemblies connected in series, each spring assembly potentially comprising individual springs connected in parallel.

[0033] Preferably, the longitudinal axes of two switching fingers are coaxial with each other, lying in a plane perpendicular to the axis of rotation of the actuating element. The circuit arrangement includes an actuator for rotating or rotating the actuating element. The actuator comprises an electric motor. However, according to the invention, the actuator can also be driven by, for example, a Bowden cable instead of an electric motor.

[0034] To enable shifting under load, it is further advantageous if the actuating element that drives the cam control is itself moved with the greatest possible driving force. To achieve this, the actuator can have a gearbox through which the actuating element is driven. The gearbox is preferably located between the electric motor or the Bowden cable on one side and the actuating element on the other.

[0035] A gear may be located at one end of the actuating element, which engages with the transmission. The gear may be formed by the actuating element itself or attached to the actuating element.

[0036] To protect the components of the circuit arrangement from external influences, the circuit arrangement has a housing-shaped sleeve in which the main gearbox shaft and the at least one planetary gear set are accommodated. The actuator is located outside the sleeve, which simplifies actuator maintenance. The actuator's gearbox is preferably also located outside the sleeve.

[0037] If the shifting mechanism is mounted on the bicycle frame, the actuator housing is preferably located in front of and below a chainstay. This protects the actuator in the event of a fall. For this reason, the actuator preferably does not protrude axially beyond the chainstays or dropouts.

[0038] According to an advantageous embodiment, the clutch is provided with face teeth, wherein the face teeth are engaged in at least one direction, transmitting torque, when the clutch is engaged, and are disengaged when the clutch is disengaged. Preferably, each clutch element has face teeth complementary to those of the other clutch element. If a clutch element is directly formed by a transmission component, for example, the planet carrier or the sun gear, the face teeth are directly attached to or formed on this transmission component.

[0039] According to a preferred embodiment, the opening angle or tooth flank angle of the torque-transmitting tooth flanks of the face gears is at least 91 degrees and at most 97 degrees, and according to a further advantageous embodiment, between 93 degrees and 96 degrees. Such an opening or tooth flank angle reduces the force required for shifting under load.

[0040] To further reduce the force required for shifting, at least the torque-transmitting tooth flanks can have a surface formed by a sliding material. For example, the face gear can be made of a composite material or coated with a sliding material. In this way, at least the torque-transmitting tooth flanks, preferably the entire face gear, can be coated with a sliding lacquer.

[0041] The axially displaceable coupling element can be connected to or arranged on the main shaft of the transmission or a torque-transmitting component of the shifting arrangement via a splined shaft connection or plug connection, allowing axial displacement but preventing rotation. The helix angle of the plug-in splines or splined shaft profile is preferably at least approximately 1 degree and at most approximately 7 degrees, more preferably at least approximately 3 degrees and at most approximately 5 degrees. The helix angle indicates the degree by which the plug-in splines or splined shaft connection is inclined or twisted relative to the axis of rotation or a plane passing through the axis of rotation. Such a helix angle also reduces the force required for shifting under load.

[0042] According to a further advantageous embodiment, the clutch, when engaged, forms a freewheel that can only transmit torque in one direction. This simplifies the design of the transmission and also allows the wheel to freewheel when a gear is engaged, ensuring that jamming due to over-constraint of the shift mechanism does not occur during a gear change.

[0043] According to a further advantageous embodiment, the actuating element is preferably axially fixed directly to the main axis of the transmission. In other words, the main axis of the transmission is preferably axially secured directly to the actuating element. This direct fixing to the main axis of the transmission, and not, for example, to the dropouts or a housing, makes it possible to keep the tolerance deviations of the switching arrangement small.

[0044] The actuating element can, for example, have a guide groove into which at least one guide finger, attached to the main axis of the transmission, projects, the actuating element being fixed axially by the guide finger and the guide groove. The guide groove always runs at the same axial height. The guide groove, or one of its sides, can serve as an axial reference position.

[0045] The at least one guide finger is preferably cylindrical. It can be screwed or pressed directly or indirectly into the main shaft of the transmission.

[0046] At least one guide finger can be forcibly guided in the guide groove.

[0047] According to one embodiment, the circuit arrangement has a coupling on the planet carrier and a coupling on the sun gear.

[0048] To increase the number of gears, at least one additional planetary gear set can be provided, in which at least one additional clutch is located on its planet carrier and / or its sun gear. Clutches can be arranged on the planet carrier, sun gear, and / or ring gear of the at least one additional planetary gear set. The planets on the planet carrier can be connected to one or more ring gears or sun gears.

[0049] In a further advantageous embodiment, the circuit arrangement can include an electronic control unit configured to actuate the actuator's electric motor depending on an electrical switching command. The electrical switching command can be generated by a switch mounted on the handlebars and transmitted to the control unit wirelessly or via a wired connection.

[0050] The electronic control unit can also be designed to receive a pedal position signal representative of the angular position of a bicycle pedal crank and to actuate the actuator depending on the pedal position signal.

[0051] For example, the electronic control unit can be configured to perform a shift when the pedal position signal represents an angular position of the pedal crank at or near top dead center. Typically, the force applied by a cyclist is less at top dead center and bottom dead center, so the load on the shifting mechanism is lower at these pedal crank angles.

[0052] The electronic control unit can further be configured to output a switching signal, particularly an electrical one, to the bicycle's motor controller when a switching operation is performed. The motor controller can be designed to regulate the auxiliary motor's power output depending on the switching signal or a switching operation of the circuit. For example, the motor controller can reduce the auxiliary motor's power output for a predetermined time when a switching operation is performed or a switching signal is received. This reduces the load on the circuit, which in turn reduces the force required for switching.

[0053] Exemplary embodiments of the invention will be explained in more detail below with the aid of drawings.

[0054] They show: Fig. 1: A schematic representation of part of a bicycle frame with a hub gear in a view from a rear left oblique angle; Fig. 2: A schematic sectional view of a hub gear with two gears in a cutaway view; Fig. 3: A schematic sectional view of the hub gear of the Fig. 2 Fig. 4: a schematic sectional view of individual components of the hub gear of the Fig. 3 Fig. 5: a schematic, perspective exploded view of the components of the Fig. 4 Fig. 6: a schematic top view of the structure of the Fig. 4 and 5 Fig. 7: a simplified representation of the geometry of the tooth contact angle α (alpha) of the toothed discs; Fig. 8: a schematic top view of a coupling in the closed state; Fig. 9: a schematic, perspective exploded view of the components of the Fig. 8 Fig. 10: a schematic top view of a further embodiment of the coupling in the open state; and Fig. 11: a schematic, perspective exploded view of the components of the Fig. 10 .

[0055] Fig. 1 The figure shows the chainstays 1 and seatstays 2 of a bicycle frame. To avoid cluttering the illustration, screws and spokes are not shown. Both components are connected to the dropouts 3, for example, by welding. The rider's mechanical pedaling power is transmitted to the rear pulley 4 via a belt drive (not shown). If a chain drive is used, a sprocket is used instead of the pulley.

[0056] To tension the belt drive, three sliding axle mounts 5 can be screwed onto the dropouts on the right and left sides. The gear mechanism 6, here a hub gear, is preferably screwed to the axle mounts 5 using a thru-axle 7. The mounting points for the disc brake caliper, which is not shown here, are located on the left axle mount 5, for example. A brake disc 8 is non-rotatably connected to the hub housing 9, hereinafter also referred to as sleeve 9, for example by screws. The spoke holes are clearly visible on the hub housing 9.

[0057] The different gear ratios within the hub gear 6 can be engaged by means of an actuator 10, which is preferably located largely or entirely in front of and below the axle 7. The actuator can be operated mechanically, electrically, or electronically via a switching cable 11. Radio transmission is also possible.

[0058] The control element for the transmission is usually located on the bicycle's handlebars and is not shown here. This element generates the shift command and can be a mechanical twist grip, switch, or push button; it can be electric, cable-operated, or hydraulic. The shift cable 11 transmits the shift command from the handlebars to the transmission. Transmission can also be electrical via cables or wirelessly.

[0059] Fig. 2 shows a hub gear as it is arranged in the Fig. 1 can be used, in an exemplary design with two passages in cutaway view.

[0060] A version with only two gears was chosen to exemplify the principles of the improved shifting arrangement. The illustrated shifting arrangement is also suitable for improving the shifting behavior of hub gears with more gears, as described in DE 197 20 794 B4 or DE 11 2019 001 604 B4.

[0061] A main transmission shaft 12 is rigidly connected to the bicycle frame via the axle mounts 5. A shift drum 13, hereinafter also referred to as the actuating element 13, rotates within the main transmission shaft. The shift drum 13 is preferably connected to or formed with an actuating gear 14 at one of its axial ends. The actuating gear 14 can be located in a section of the main transmission shaft 12, hereinafter referred to as the shift housing 15. The shift housing 15 is, for example, connected to an axle plate 16 on the left side. All reaction torques are transmitted from the main transmission shaft 12 via the shift housing 15 to the axle plate 16 and then introduced into the axle mounts 5.

[0062] Inside an actuator housing 17 is a gearbox 19 that transmits a rotary motion within the actuator housing 17 to the switching drum 13. The actuator housing 17 may have a removable cover 18. In the exemplary embodiment shown, Fig. 2 An electric motor 20 is located inside the actuator housing 17, which preferably causes the switching drum 13 to rotate via the gearbox 19. The electric motor 20 is not visible in this illustration because it is covered by the cover 18 of the actuator housing 17. In the illustrated embodiment, the actuator housing 17 transitions into the switching housing 15.

[0063] With an electric motor 20 and a suitable gear ratio of the gearbox 19, high switching forces and torques can be achieved at the shift drum 13. In conventional designs, the shift drum 13 is usually secured axially at both ends via its flat surfaces 21 against axial displacement. If the drive shaft 7 is tightened excessively in prior art designs, the shift drum can jam. In the illustrated embodiment, however, the gearbox main shaft 12 is clamped rotationally fixed between the two dropouts 3 by means of the drive shaft 7 and the drive shaft nut 34. An axial clamping of the gearbox main shaft 12 with the drive shaft 7 tightened does not lead to jamming of the shift drum 13, since the shift drum 13 is spaced at its flat surfaces 21 from the gearbox main shaft 12 and the shaft plate 16. The shift drum 13 can be driven within the gearbox main shaft 12 by the actuator or...electric motor, rotating.

[0064] The gear arrangement thus has a main gearbox shaft 12 that can be mounted non-rotatably on the bicycle frame, with a driver 26 rotatably mounted on the main gearbox shaft and a sleeve 9 rotatably mounted on the shaft. The main gearbox shaft 12 is hollow and inside the hollow body is an actuating element 13 which can assume different angular positions relative to the main gearbox shaft 12.

[0065] In the exemplary design of the Fig. 2 On the upper or outer surface of the shift drum 13, at least one guide groove 23 is located, into which at least one, for example, cylindrical guide finger 22a engages. The guide groove 23 has axial side surfaces 23a along which the guide finger 22a slides during the rotation of the shift drum 13. The distance of the axial side surfaces of the guide groove 23 from an axial fixed point is at least nearly the same in each gear position compared to all other grooves also arranged on the shift drum. In the simplest design, the guide groove 23 is an annular, in particular circular, milled or machined recess on the outer surface of the shift drum 13. The at least one guide finger 22a and the guide groove 23 fix the main transmission shaft 12 and the actuating element 13 in the axial direction relative to each other.Thus, the shift drum 13 is precisely guided during its rotation relative to and within the main axis of the transmission 12 by the guide finger 22a and the guide groove 23.

[0066] In a preferred embodiment, a detent mechanism is provided by which the shift drum 13 engages at spaced-apart detent points as it rotates. For example, the shift drum 13 can be provided on its circumferential surface with one or more circumferentially spaced recesses 24 that define the angular positions of the detent points. A spring-loaded pressure piece 25 can snap into the recesses 24 with its spherical end and prevent free rotation of the shift drum 13 within the main axis 12 of the transmission. A recess serving as a detent point 24 is preferably located precisely at the respective angular position of the shift drum 13 in which a specific gear is engaged. In this way, backlash within the actuator 10 can be eliminated. Furthermore, the detent mechanism makes it possible to keep the electric motor 20 within the actuator 10 de-energized in the respective gear positions.

[0067] A driver 26, at least one planet carrier 27, at least one ring gear 28, and at least one sun gear 29 of a planetary gear set 29a are arranged coaxially with the hub housing 9. In an exemplary embodiment, the ring gear 28 forms the output to the hub housing 9. The torques are fed into the hub gear 6 via the pulley 4, which is mounted on or rotatably connected to the driver 26. The driver 26 is preferably designed as a hollow shaft and is supported, for example, by two ball bearings 33 on the main shaft 12 of the gear set. The hub housing 9 can be supported on the main shaft 12 and on the driver 26 by ball bearings 33.

[0068] If more than two gears are required, more planetary gears are simply used, as described in DE 197 20 794 B4 or DE 11 2019 001 604 B1.

[0069] Fig. 3 The simple 2-speed planetary gearbox is shown. Fig. 2 in a schematic sectional view.

[0070] A coupling 30 is configured to connect the sun gear 29 to the main transmission shaft 12 in at least one switching state, either directly or indirectly, and to release the rotationally fixed connection between the sun gear 29 and the main transmission shaft 12 in at least one other switching state. The coupling 30 comprises a coupling element 30a that is axially displaceable in the direction of the axis of rotation 35 and an axially fixed coupling element 30b, which here is formed by the sun gear 20 itself. Both coupling elements 30a, 30b preferably have an internally projecting tooth 36 extending radially inwards and complementary face teeth 37, 38. The axially displaceable coupling element 30a is rotationally fixed to the main transmission shaft 12 via the internal tooth 36, which may have external teeth complementary to the respective internal toothing.

[0071] The two face-side planar teeth 37 and 38 have tooth flanks or pressure surfaces 39 ( Fig. 6 ), which, depending on the angular position of the actuating element 13, i.e., the switching state or position, either touch or do not touch. When a torque is transmitted, the tooth flanks 39 touch. The face teeth 37, 38 are arranged coaxially to each other. Their axial distance depends on the angular position or switching position of the actuating element 13.

[0072] Additionally or alternatively, the planet carrier 27 can be connected to the driver 26 in at least one switching state, either directly or indirectly, by means of a further switchable clutch 31, preventing rotation. Like the clutch 30, the switchable clutch 31 is also provided with an axially movable clutch element 31a and an axially fixed clutch element 31b. The axially fixed clutch element 31b can be formed directly by the planet carrier 27. For this purpose, a face gear 40 can be provided on the planet carrier 27, which can be positively engaged with the face gear 37 of the axially movable clutch element 31a. Preferably, the face gear 37 of the movable clutch element 31 is automatically engaged in the face gear 40 on the planet carrier 27 by an axially acting spring 41.

[0073] The drive torque is transmitted from the external teeth 42 of the driver 26 to the internal teeth 36 of the coupling element 31a. The axial position of the coupling element 31a can be changed by means of at least two switching fingers 22, only one of which is shown. The switching fingers 22 can have a cylindrical surface, an external thread, and a head and can be rigidly connected to the coupling element 31a, for example, by screwing them in. The switching fingers 22 of the coupling 31a are only indirectly connected to the actuating element 13 via the sliding ring 43. The switching fingers 22 for disengaging the planet carrier are rotatable relative to the actuating element 13 and the sliding ring 43. The sliding ring 43 transmits the axial switching movement from the actuating element 13 to the switching fingers 22. The rotatable connection between the switching fingers 22 and the switching ring 43 is...The actuating element 13 is necessary because the driver 24, mounted on the axis 12 via ball bearings 44, rotates and the switching information or movement must therefore be transferred from a stationary element to a rotating element.

[0074] The face-side planar toothing 40 on the planet carrier 27 is in Fig. 3 The diagram shows the clutch in the open or disengaged switching state. In the open switching state, the cylindrical switching finger 22 of the clutch 31 is constantly in sliding contact with the sliding ring 43. The sliding ring 43 holds the clutch 31 against the axially acting spring 41 in the open switching state. In this switching state, the spring 41 is unable to close the clutch 31.

[0075] At least two further shift fingers 22 can be attached to the sliding ring 43, for example, by being screwed in. During a shifting operation, the shift fingers 22 move within an opening 46 of the main transmission shaft 12 and enter the shift groove 45, along which they slide. Only one shift finger 22 is shown here.

[0076] In the exemplary design of the Fig. 2 The actuating element 13 has two switching grooves 45, which, together with the switching fingers 22 projecting into them, each form a cam guide 45a for the axially movable coupling element 30a, 31a. The cam guide 45a ensures axial movement of the switching fingers 22 when the actuating element 13 rotates about its axis of rotation 35 during a switching operation. The switching fingers 22 projecting into the switching grooves 45 form the cam blocks in the cam guide. The main transmission shaft 12 is perforated by openings 46 in the vicinity of, and in particular radially opposite, the switching grooves 45. The switching fingers 22 projecting into the switching grooves 45 extend through the main axis of the transmission 12. In order to allow axial movement of the cylindrical switching fingers 22 while they slide with their cylindrical surface within a switching groove 45 of the actuating element 13 during the switching process, the openings 46 are preferably elongated holes.

[0077] The switching fingers 22 can be positively guided in the respective switching groove 45. For example, the switching fingers 22 are moved by both sides of the switching groove 45. Alternatively or additionally, the switching fingers 22, which enter a switching groove 45, can be pressed against only one side or flank of the switching grooves 45 permanently or only during a switching operation by an axial spring, for example the spring 41. In this case, only this one side or flank acts as a cam guide.

[0078] The main transmission shaft 12 can have an external toothing 47 at at least one point, which is axially displaceable but rotationally fixed to one or more internal toothings 36 of coupling elements 31a or to a sliding ring 43 with internal toothing 43. The sliding ring 43 can be considered part of the axially displaceable coupling element 31a. This external toothing 47 can, on the one hand, transmit the reaction torques of the sun gear 29 to the dropouts 3 and, on the other hand, ensure that no shear forces can act on the cylindrical shift fingers 22 screwed into the sliding ring 43.

[0079] In order for the switching grooves 45 to precisely define the axial position of the switching fingers 22, the actuating element 13 should have no noticeable axial play relative to the main transmission axis 12. This is achieved, as described above, by the guide groove 23 and the guide finger 22a.

[0080] In an advantageous embodiment, the axially opposing surfaces of the grooves 23, 45 have a distance that is equal to or only slightly greater than the diameter of the cylindrical fingers 22, 23 that each enter the groove 23, 45.

[0081] A switching groove 45 serving as a cam guide differs from the guide groove 23 in that the switching groove 45 has an axial distance to the guide groove 23 that changes in the circumferential direction of the main axis of the transmission 12, or that there is only one axial side surface that can assume a sliding connection with a cylindrical switching finger 22.

[0082] Tilting of an axially displaceable coupling element 30a, 31a during the axial switching movement can be particularly well prevented if the couplings 30, 31 or the sliding ring 43 each have two circumferentially spaced switching fingers 22 that engage in the respective switching groove 45. Likewise, two or more circumferentially spaced guide fingers 22s can engage in the guide groove 23. Additionally, it is advantageous if the cylindrical axes of the at least two cylindrical switching fingers 22, 22a intersect at at least one point.

[0083] It is even better and more space-saving if at least two of the switching fingers 22, 22a of a groove 23, 45 have cylinder axes lying coaxially and perpendicular to the axis of rotation 35 of the actuating element 13.

[0084] In the illustrated embodiment, the switching function is achieved by connecting the actuating element 13 to an electrically operated actuator 10, the actuator 10 being located outside the sleeve 9. When the actuator 10 is actuated, the angular position of the actuating element 13 relative to the axis 12 changes, causing the switching fingers 22 to be axially displaced in the switching grooves 45 due to their rotation-angle-dependent axial position. The radial position of the movable couplings 30, 31 and their coupling elements remains unchanged.

[0085] During such a switching operation, the face teeth 38 of the clutch 30 must be moved axially out of engagement, in particular pulled out. If the switching operation takes place under load, a high torque may have to be applied to the shift drum 13, because the high static friction on the face teeth 38 and the internal teeth 36 must be overcome briefly. In the illustrated embodiment, an electric motor 20 or, if necessary, a Bowden cable can apply a high torque to the shift drum 13 via the transmission 19.

[0086] The electric motor 20 can be very small and lightweight if it is operated at high speed and the gearbox 19 is connected to the shift drum 13 via several gear stages 49a to 49e, which are preferably all located within the actuator housing 17. The gear stages are arranged in Fig. 3 Examples are shown as spur gear units 49a, 49b, 49c, 49d and as worm gear units 49e. Other transmission types and numbers of gear stages are possible.

[0087] If the actuator 10, when installed on the bicycle, is located largely in front of and below the wheel axle 35 and is also offset slightly inwards in the axial direction relative to the dropouts, or does not protrude too far, it is well protected against damage. The hub housing 9 can be made small if the gear 14 and the transmission 19 are located inside the actuator housing 17 but outside the hub housing 9. If at least three gears of the transmission stages 49a to 49e are arranged coaxially with the axis of rotation 35 of the actuating element 13, a collision or overlap with the commonly used design of the dropouts 3 can be prevented.

[0088] Additionally, it is advantageous if an electronic control unit 50 is located within the actuator housing 17, which serves to control the electric motor 29 and to process signals from a sensor system 51. One or more sensors 51 can be located in the actuator housing 17, which determine the position or orientation of the shift drum or its shift position and transmit this information to the control unit 50. The control unit 50 is preferably configured to communicate wirelessly or via a wired connection with other control elements located on the bicycle. In this way, for example, the torque of the auxiliary motor of an electric bicycle can be reduced, at least temporarily, when a shifting operation is to be carried out in order to reduce the static friction on the gear teeth 36, 37, 38, 42, 47. The control unit 50 can also be configured, for example, to carry out a shifting operation depending on the crank position of the bicycle.For this purpose, the control unit 50 can be configured to output a switching signal via line 11, which is representative of a switching operation currently being carried out. For example, the control unit is configured to actuate the electric motor 20 when a pedal is at bottom dead center.

[0089] Fig. 4 The figure shows the main transmission shaft 12, an axially acting spring 41, the clutch 30 with face and internal teeth, the sun gear 29, two spring washers 52, and two diametrically opposed shift fingers 22 in cross-section. This illustration clearly shows that, in an advantageous embodiment, at least two shift fingers 22 are provided, each of which can have a cylindrical surface 53, an external thread 54, and a head 55, and can be screwed into a clutch component 30. The cylindrical surfaces 53 establish the connection to the actuating element 13. The advantage of the screwed-in or screwable shift fingers 22 is that, in this embodiment, the shift fingers 22 can be automatically assembled during production, and complete freedom from backlash is achieved between the shift finger 22 and the axially displaceable clutch element 30a. Furthermore, with such an arrangement, the shift assembly 6 can be disassembled more easily.The external thread 54 is preferably arranged between the cylindrical outer surface 53 and the head 55. The head 55 is preferably provided with an internal or external hexagon socket or a Torx connection.

[0090] Due to the symmetrical application of force F via the two diametrically opposed shift fingers 22, tilting is prevented and shifting under load is simplified. The direction of action of the spring 41 corresponds to the direction in which the clutch 30 is engaged.

[0091] When disengaging under load, the axially movable coupling component 30a with its internal teeth 36 ( Fig. 3 ) and its face-side planar teeth 37 are pulled out of static friction against the force of the spring 41. As soon as the axial switching movement has begun, the static friction transitions into a lower sliding friction. After a certain distance of the axial switching movement has been traversed, the face-side planar teeth 37 and 38 are disengaged and the clutch 30 is in an open state. The clutch 30 then no longer transmits any torque. In the Fig. 4 Figure 30 shows the closed state of the clutch. To further improve shiftability under load, the design of the axially displaceable clutch bodies is of great importance. The plane X runs in the Fig. 4 centrally through the face-side planar teeth 37, 38. An advantageous embodiment of the face-side planar teeth is explained in more detail below by means of a section through the plane.

[0092] Fig. 5 shows the components of the Fig. 4 in an exploded view. The main gear shaft 12 has the external teeth 47 and the openings 46. The external teeth 47 can consist of only a few, for example two to ten, in particular two to five, axially extending grooves. The internal teeth 36 are complementary to the external teeth 47. Furthermore, the main gear shaft 12 can have circumferentially extending grooves 56 on its outer surface for mounting spring washers 52.

[0093] The sun gear 29 has a sliding bearing surface 57 and can rotate on the main shaft 12 of the transmission, but cannot move axially due to the axial fixation by, for example, the spring washers 52. Of course, a rolling bearing can also be used for the sun gear instead of a sliding bearing. The face teeth 38 are located on an end face of the sun gear 29. They can be milled or pressed in. The coupling element 30a has internal teeth 36 that fit easily onto the external teeth 47 of the main shaft 12 of the transmission as a splined connection. When engaged, the face teeth 37 of the coupling element 30a can transmit a torque to the sun gear 29 in a positive-locking manner.

[0094] Face teeth in clutches according to the prior art are usually held in the engaged state by a single helical compression spring. However, a single helical compression spring is not capable of maintaining a constant surface pressure on all teeth of the face teeth 37 and 38 in the engaged state. Therefore, a wave spring 41 is preferred instead of a helical compression spring. A wave spring 41, particularly one with more than two individual springs connected in parallel, allows the surface pressure on all teeth of the face teeth 37 and 38 to be kept constant in the engaged state compared to the prior art, thus preventing slippage of the transmission. Slippage between two gears must be prevented in any case, as a bicycle rider could be injured in this situation.A wave spring 41 is, generally speaking, a spring assembly consisting of several leaf springs connected in parallel and distributed around the circumference.

[0095] Fig. 6 shows the exemplary structure of the Fig. 4 and Fig. 5 The view is a top view of plane X. The sun gear 29 is rotatably mounted on the main transmission shaft 12 and axially secured against displacement by the spring rings 52. The clutch 30 is held axially in the closed position by the spring 41. As can be seen in detail A, the face teeth 37 on the movable clutch component 30 engage with the face teeth 38 on the sun gear 38 via the tooth flanks 39, transmitting torque. The tooth flanks 39 of the face teeth 37 and 38 contact each other when the clutch is closed during torque transmission and do not contact each other when the clutch is open.

[0096] In an advantageous embodiment, the tooth flanks are arranged tilted on average by a tooth contact angle α between 91 and 97 degrees inclusive, relative to a face-side planar surface 60, from which the toothing 61 extends axially. The planar surface 60 is perpendicular to the axis of rotation 35 ( Fig. 3 A tooth contact angle α in the range of approximately 91 degrees to approximately 97 degrees, particularly between 93 and 96 degrees, reduces the force required to disengage the clutch. Self-disengagement is not possible at such a tooth contact angle due to the geometry and the spring 41. In prior art designs, this angle is typically 90 degrees or less to keep the clutch self-locking.

[0097] In general, the two coupling elements 30a, 30b and 31a, 31b, which have face teeth 37, 38, can also be referred to as coupling discs or toothed discs 62. In the illustrated embodiment, the coupling discs 62 are designed as a modified face tooth coupling with a freewheel function. In an advantageous embodiment, torque should therefore only be transmitted in one direction. The coupling discs 62 are advantageously made of hardened steel. The diameter, the number and size of the teeth, and the installation situation are described in the following. Fig. 2 bis 6 These are only examples.

[0098] Fig. 7 Figure 6 shows a simplified representation of the geometry of the toothed discs 62. Fm represents the contact force generated by the torque, Fr the resulting static friction, and α (alpha) the tooth contact angle. Fn is the normal force acting on the pressure surfaces 39. The optimal tooth contact angle α (alpha) depends on the coefficient of static friction µ₀ of the friction pair. The limiting condition for self-locking is met when there is a force equilibrium between the self-disengaging force Fa and the static friction force Fr. The coefficient of static friction µ₀ can vary widely between 0.08 and 0.5, depending on the lubrication and material selection. For example, the limiting angle for self-locking between bodies made of hardened steel with lubrication and a static friction coefficient µ₀ = 0.08 is approximately 5 degrees. Fig. 6 This corresponds to an angle of approximately 95 degrees. The spring forces of the wave spring 41 are not taken into account in this calculation and, since a uniform pressure is exerted on the toothed discs 62, ensure a reliable transmission of torques without self-disengagement or slippage of the clutch.

[0099] To reduce friction, the gear teeth can have a surface coated with a sliding material or be made of a sliding material. For example, at least the torque-transmitting tooth flanks 39, but preferably the entire gear teeth, can be coated with a sliding varnish. The toothed discs 62 can also be made of a composite material with a sliding material component.

[0100] The clutch described above can be used independently of a hub gear in general as a switchable clutch with a freewheel function. It can be designed as a pre-assembled unit that is mounted as a whole on the main transmission shaft 12. This is explained below with reference to the Fig. 8 und 9 explained.

[0101] The toothing 61 can be used whenever a connection capable of transmitting a torque M in one direction is required between two bodies. It is irrelevant whether the components to be coupled are stationary or rotating when the coupling is engaged. The components to be coupled preferably have the same axis of rotation 35. When the coupling is engaged and torque is being transmitted, the contact surfaces 39a of one toothed disc 62a are in engagement with the contact surfaces 39b of the opposite toothed disc 62b. The toothing 61 of the toothed discs 62a and 62b has back surfaces 63a and 63b that point away from the contact surfaces 39a and 39b, and in an advantageous embodiment, when the coupling is engaged and torque is being transmitted, the back surface 63a of one toothed disc 62a is not in contact with the back surface 63b of the other toothed disc 62b.

[0102] If both toothed discs 62a and 62b are rotated against the load transmission direction with the clutch closed, so that the back surfaces 63a and 63b are pressed against each other, then the back surfaces 63a and 63b slide against each other and a freewheeling function is achieved. In the open state of the clutch, the teeth 61 of both toothed discs 62 are spaced apart from each other.

[0103] For switching, preferably only one toothed disc 62b performs an axial movement along the axis of rotation 35. This toothed disc 62b usually transmits the torque via a splined connection 65, for example, the external and internal splines 37, 47 described above, to a clutch shaft 64.

[0104] The Fig. 8 und 9 Figure 64 shows, by way of example, the clutch shaft 64 with external teeth 42, 47 and the toothed disc 62b with internal teeth 36. The internal teeth 36 and the external teeth 42, 47 together form a sliding splined connection 65. However, this is only one exemplary embodiment of the splined connection 65. A toothed disc 62b can also have external teeth and slide in a hollow clutch shaft with internal teeth. When shifting under load, the static friction within the splined connection 65 must also be overcome. The torque M to be transmitted generates a normal force Fn on the tooth flanks of the splined connection 65 with helix angle β (see Figure 6). Fig. 6 The helix angle β is measured axially between a plane containing the axis of rotation 35 and the tooth flanks of the splined coupling 65. Due to the helix, this normal force Fn has an axial force component Fa, which counteracts the frictional force Fr. The helix angle β and the coefficient of static friction µ 0 within the splined coupling must be selected such that the coupling does not open automatically during torque transmission. In an advantageous embodiment, the splined coupling 65 therefore has a helix angle β between 1 and 7 degrees. Like the face gear, the surface of the splined coupling can also have a sliding material. Alternatively, the face gear can also contain a composite material with a sliding material component.

[0105] Fig. 9 Figure 1 also shows, in an exemplary embodiment, the two openings 46 designed as elongated holes and the external and internal teeth 36, 42, 47 of the clutch shaft 64. However, an elongated hole 46 is not absolutely necessary. Any type of opening within the clutch shaft 64 is possible, provided the shift finger 22 has sufficient axial movement. In the assembled state, the cylindrical surface 53 of the shift fingers 22 is located within the openings 46. Since the shift fingers 22 are firmly screwed or otherwise fastened in the axially movable toothed disc 62b, the actuating element (not shown here) inside the clutch shaft 64 can move the toothed disc 62b without play. This is an advantage compared to the prior art.

[0106] Furthermore, in Fig. 9 The figure shows that an axially non-movable toothed disc 62a can rotate on a sliding bearing surface 57 about the axis of rotation 35 and can be axially fixed in place by, for example, two spring washers 52. The splined connection 65 typically has a small amount of play in the circumferential direction to allow slight axial movement of the toothed disc 62b on the clutch shaft 64. To ensure uniform engagement of the pressure surfaces 39a with the adjacent pressure surfaces 39b, the axially movable toothed disc 62b is connected to a spring element 41 with at least two parallel individual springs 59, for example, a wave spring.

[0107] The wave spring of the Fig. 8 und 9 Figure 41 is an example of a spring element that generates a uniform axial contact force around its circumference at its end face. The individual springs shown are several leaf springs 59a, 59b, 59, 59d, etc., connected in parallel, forming an element with more than two parallel individual springs 59. Wave springs are coiled, resilient components made from flat material. The illustrated embodiment is a multi-layer wave spring with parallel ends. A wave spring can be made from wound flat wire, which acquires a spring effect through incorporated waves. Wave springs are superior to coil springs in the described application due to their lower profile and the uniform contact pressure for the same force.

[0108] In Fig. 10 und 11 Figure 1 shows a further embodiment of the switchable freewheel clutch. In this embodiment, instead of the wave spring, a spring 41 with a plurality, for example twelve, of parallel connected individual springs 59a, 59b etc., for example coil springs, is provided.

[0109] The individual springs are preferably encased at both ends with an annular plastic disc 66 through which the clutch shaft 64 extends. This creates an integral spring element with more than two parallel individual springs 59, which is in contact with the axially movable toothed disc 62b and advantageously presses it uniformly against the axially stationary toothed disc 62a.

[0110] In Fig. 10 When the clutch 62 is open, at least two shift fingers 22 engage in the shift groove 45 of the actuating element 13. The shift groove 45 and the actuating element 13 are in Fig. 10Not shown. In this illustration, the torque M is transmitted from the clutch shaft 64 to the axially movable toothed disc 62b, but no torque is transmitted from there to the axially stationary toothed disc 62a. Reference sign

[0111] 1 Chain stays 2 Seat stays 3 Dropouts 4 Rear pulley 5 Axle mounts 6 Gearbox assembly, in particular hub gears 7 Thru axle 8 Brake disc 9 Sleeve 10 Actuator 11 Shift cable 12 Main gearbox shaft 13 Shift drum, actuating element 14 Actuating gear 15 Shift housing 16 Axle plate 17 Actuator housing 18 Actuator housing cover 19 Gearbox 19a Gear on actuating element 20 Electric motor 21 Flat surfaces of the shift drum 22 Shift finger 22a Guide finger 23 Guide groove 23a Side surface of the guide groove 24 Recess as detent point 25 Spring-loaded pressure piece 26 Driver 27 Planetary carrier 28 Ring gear 29 Sun gear 29a Planetary gear set 30 Clutch 30a Axial sliding coupling element 30b axially fixed coupling element 31 coupling 31a axially sliding coupling element 31b axially fixed coupling element 32 coupling;Clutch assembly 33 Ball bearing 34 Axle nut 35 Rotation shaft 36 Internal toothing 37 Face toothing on the sliding clutch component 38 Face toothing on the fixed clutch element 39 Tooth flank or pressure surface 39a Pressure surfaces on axially fixed toothed disc 39b Pressure surfaces on axially movable toothed disc 40 Face toothing on the planet carrier 41 Spring 42 External toothing on the driver 43 Sliding ring 44 Ball bearing 45 Shift groove 45a Cage control 46 Opening 47 External toothing of the main gearbox shaft 48 Gap 49a - 49e First to fourth gear stage of the gearbox 19 50 Electronic board 51 Sensor 52 Spring washers 53 Circumferential surface 54 Thread 55 Head 56 Groove for spring washers 57Sliding bearing surface 58Internal thread 59Spring element with more than two parallel connected individual springs 59a - 59dIndividual springs 60Flat surface 61Tooth-shaped protrusion 62Toothed discs;Clutch discs 62a Axially non-movable toothed disc 62b Axially movable toothed disc 63 Back surface 63a Back surfaces of the axially non-movable toothed disc 63b Back surfaces of the axially movable toothed disc 64 Clutch shaft 65 Splined connection 66 Plastic disc Fa Self-disengaging force Fm Contact force Fn Normal force Fr Static friction force M Torque µ 0 Coefficient of static friction α Tooth contact angle; Opening angle of the face teeth β Helix angle of the splined connection;

Claims

1. Gearshift assembly (6) for a bicycle, in particular for a hub gear, comprising - a hollow main gear shaft (12) fixable in a rotationally rigid manner relative to a bicycle frame (1, 2), - a driver (26) mounted rotatably on the main gear shaft, - at least one planetary gear (29a) having at least one gear component (27, 29) rotatably mounted on the main gear shaft in the form of a planet carrier (27) or a sun gear (29), - a clutch (30, 31) including a clutch element (30a, 31a) that is axially displaceable relative to the main gear shaft between an engaged and a disengaged state, wherein the clutch component is connected to the main gear shaft in a rotationally fixed manner in the engaged state of the clutch and is connected so as to be freely rotatable relative to the main gear shaft in the disengaged state of the clutch, - an actuating element (13) mounted in the main gear shaft and rotatable relative to the main gear shaft, - at least one cam control (45a) that connects the actuating element to the axially movable clutch element and is configured to convert a rotational movement of the actuating element into an axial displacement of the axially movable clutch element, - a housing-shaped sleeve (9), in which the main gear shaft(12) and the at least one planetary gear (29a) are housed, - an actuator (10) for rotating the actuating element (13), wherein the actuator (10) is located outside the sleeve (9) and comprises an electric motor (20), wherein the cam control comprises at least two shift fingers (22) moved by a cam guide (45) of the cam control and spaced apart from one another in the direction of rotation of the actuating element, which extend from the axially movable clutch element through an opening (46) in the main gear shaft into the cam guide, and wherein the clutch (30, 31) comprises an axially acting spring (41) that acts on the axially displaceable clutch element (30a, 31a) and moves the axially displaceable clutch element toward the axially fixed clutch element (30b, 31b) of the clutch.

2. Gearshift assembly (6) according to claim 1, wherein the spring (41) comprises at least two individual springs (59a, 59b, 59c, 59d) connected in parallel.

3. Gearshift assembly (6) according to any one of claims 1 to 2, wherein the clutch (30, 31) is provided with frontal crown-wheel gearings (37, 38) on its end faces, and wherein the frontal crown-wheel gearings are in engagement in the engaged shifting state, transmitting torque in at least one direction, and are out of engagement in the disengaged shifting state.

4. Gearshift assembly (6) according to claim 3, wherein the opening angle of the torque-transmitting tooth flanks (39) of the crown-wheel gearings (37, 38) is at least 91 degrees and at most 97 degrees.

5. Gearshift assembly according to claim 3 or 4, wherein at least the torque-transmitting tooth flanks (39) have a surface formed from a sliding material.

6. Gearshift assembly (6) according to any one of claims 1 to 5, comprising an electronic control unit (50), wherein the control unit (50) is configured to actuate the electric motor (20) in response to an electrical control signal.

7. Gearshift assembly (6) according to any one of claims 1 to 6, wherein the individual springs (59a, 59b, 59c, 59d) are evenly distributed in the circumferential direction around the axis of rotation (35).

8. Gearshift assembly (6) according to any one of claims 1 to 7, wherein the spring (41) is a torsion spring.

9. Gearshift assembly (6) according to any one of claims 1 to 8, wherein the spring (41) comprises a plurality of spring assemblies, and a spring assembly comprises a plurality of individual springs (59a, 59b, 59c, 59d).

10. Gearshift assembly (6) according to any one of claims 1 to 9, wherein the individual springs (59a, 59b, 59c, 59d) are leaf springs.

11. Bicycle, in particular an electric bicycle, comprising a gearshift assembly (6) configured as a hub gear according to any one of claims 1 to 10.

12. Bicycle according to claim 11, wherein the gearshift assembly (6) comprises an actuator (10) for rotating the actuating element (13), and the actuator (10) is arranged in an actuator housing (17) that is located in the direction of travel of the bicycle in front of the main gear shaft (12) and below a chain stay (1).

13. Bicycle according to claim 11 or 12, wherein the bicycle comprises an auxiliary motor and a motor controller for adjusting the power of the auxiliary motor, and wherein the motor controller is configured to control the power of the auxiliary motor depending on a shifting operation of the gearshift assembly (6).