Drive unit for a transport means that can be driven simultaneously by drive energy provided by human muscle power and via an electric motor, and transport means comprising such a drive unit
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- KILLWATT GMBH
- Filing Date
- 2024-07-11
- Publication Date
- 2026-06-17
Smart Images
Figure EP2024069705_13022025_PF_FP_ABST
Abstract
Description
DRIVE UNIT FOR A MEANS OF LOCOMOTION THAT CAN BE DRIVED SIMULTANEOUSLY BY DRIVE ENERGY PROVIDED BY HUMAN MUSCLE POWER AND AN ELECTRIC MOTOR, AND MEANS OF LOCOMOTION WITH SUCH A DRIVE UNIT
[0001] The invention relates to a drive unit for a means of locomotion that can be driven simultaneously by drive energy provided by human muscle power and by an electric motor, and to a means of locomotion with such a drive unit.
[0002] Generic means of transport include, for example, single- or multi-track vehicles such as bicycles, especially electric bicycles, e-bikes, or pedelecs, but also water bikes, pedal boats, or wheelchairs. In particular, generic means of transport include vehicles of vehicle classes L1e, L2e, L3e, L4e, L5e, L6e, and L7e according to Article 4 of EU Regulation 2013 / 168 / EU of January 15, 2013.Furthermore, this includes in particular vehicles with a maximum design speed of up to 6 km / h, vehicles intended exclusively for use by physically disabled persons, such as wheelchairs, vehicles intended exclusively for use in sporting competition, pedal-driven bicycles with pedal assistance equipped with an auxiliary electric motor with a maximum rated continuous power of up to 250 W, the assistance of which is interrupted when the rider stops pedaling and the assistance of which is progressively reduced as the vehicle speed increases and is interrupted before the vehicle speed reaches 25 km / h, self-balancing vehicles with an electric motor drive, sports vehicles with pedal drive, pedal-driven vehicles which do not have at least one seat and pedal-driven vehicles with an R point (according to ECE-R 17) < 400 mm.They often have a front wheel and at least one rear wheel that are connected to each other via a frame. However, there may also be multiple rear wheels, for example two rear wheels, and / or multiple front wheels, for example two front wheels, in particular in any combination. These can, for example, be arranged next to each other transversely to a forward direction of travel, as in a wheelchair, a tricycle or a vehicle with a sidecar, or one behind the other in the forward direction of travel, as in a tandem. Such means of transport are increasingly being equipped with at least one electric motor to assist the user in propelling the means of transport. Typically, they are not powered by this electric motor alone, but rather the electric motor assists the user in propelling the means of transport using their own human muscle power.The level of support is usually selectable. In this way, a user can exert as much of his or her own energy as he or she can or wants while traveling with such a means of transport, while still moving at a comfortable speed that is also usable in everyday life.
[0003] In addition to assisting the user in propelling the means of transport, it is also already known to equip drive units for such means of transport with two electric motors and a summing gear. In this way, a continuously variable transmission (CVT) can be realized, which is controlled, for example, by a control unit. The operator then does not have to search for the currently appropriate gear from a multitude of available discrete gears, as is the case with conventional bicycles, for example. Instead, the gear ratio appropriate for the current driving situation is continuously adjusted by the control unit by controlling at least one of the electric motors on the summing gear. Such drive units are known, for example, from EP 1 642 820 A1 and EP 2218 635 A1. Planetary gears are used as summing gears in these documents.WO 2022 / 078730 A1 discloses a generic drive unit in which a ring gear of a drive shaft gear and a ring gear of a variation shaft gear are designed to be non-rotatable relative to one another and rotatable relative to the support structure of the drive unit about a common axis of rotation and transmit the summed drive energy from human muscle power, a drive electric motor and a variation electric motor to the output drive shaft.
[0004] The drive unit can be arranged as a hub motor on or near a wheel hub, or as a mid-drive motor on or near a drive bearing, for example, the bottom bracket. In both cases, the support structure of the transmission is then preferably mounted in a rotationally fixed manner relative to the respective frame of the means of transport. It is desirable for the drive unit to be as compact as possible, particularly with regard to its extension in the axial direction of the rotational axis of the pedal axle or the wheel axle, so as not to negatively impact ride comfort for the operator. This therefore particularly applies to the axial extension of the drive unit in the axial direction of the output drive shaft.
[0005] The object of the present invention, based on known drive units, is therefore to provide a way to ensure reliable operation of the drive unit while maintaining the narrowest possible design. At the same time, the drive unit should be able to cover the widest possible range of functions.
[0006] The solution is achieved with a drive unit and a means of transport with such a drive unit according to the independent claim. Preferred developments are specified in the dependent claims.
[0007] The drive unit according to the invention comprises a support structure. The support structure represents the essential support structure for the transmission elements of the drive unit, which are described in more detail below. The support structure can at least partially form part of an outer housing. It is essential that the transmission and drive elements, which are described in more detail below and are rotatable about the rotation axis, such as in particular a rotor, the two flexsplines, a ring gear, the transmission input shaft and the transmission output shaft, are rotatable relative to this support structure and are at least partially supported relative to it, directly or indirectly, via one or more suitable bearings. The support structure is thus in particular a bearing housing, via which supporting forces against a vehicle frame of the means of transport can be absorbed.Furthermore, it can also additionally provide at least partial protection for these drive and transmission elements and, for this purpose, be designed to be essentially closed to the outside environment except for the mechanical input and output connections. Additionally or alternatively, removable wall elements can also be included to provide this protection. These are preferably arranged detachably on the support structure. Particularly in the case where the drive unit is used as a mid-engine, the support structure can be designed for mounting on a vehicle frame and, for this purpose, can be connected to the vehicle frame via a part of the outer housing at least partially formed by the support structure, for example via a suitable connecting flange.The drive unit can also be used as a hub motor, in which case the support structure can be designed to extend completely through the axis of rotation from one side to the other in the axial direction of the axis of rotation, such that at least one connection of the drive unit protrudes beyond this support structure at the front. This can be the case on one side, but in particular also on both sides, such that the drive unit can be used to fasten the drive unit to the frame of the means of transport in a rotationally fixed manner via these two frontal projections, in particular along the axis of rotation. If the drive unit is to be used as a hub motor, the support structure can thus have connection points to the hub axle of the means of transport or can itself form part of the hub, which is rotationally rigid and stationary relative to the frame when assembled.
[0008] The drive unit further comprises an input drive shaft for transmitting drive energy generated or provided by human muscle power. The input drive shaft can therefore, particularly when the drive unit is used as a mid-engine, be the crankshaft of a bicycle, for example, or be connected to it in a rotationally fixed manner. Alternatively, the input drive shaft can be connected in a rotationally fixed manner to a traction gear, such as the chainring. The input drive shaft can also be connected to the output of a traction transmission, particularly when used as a hub motor. The input drive shaft is thus arranged such that it can be set in rotation by an operator or driver of the means of transport using human muscle power, for example by pedaling the bicycle. This can occur directly or indirectly.In particular, it is intended that this should take place in front of an electric motor in the direction of power flow from the point of introduction of human muscle power into the entire drive train.
[0009] The drive unit according to the invention further comprises an output shaft for transmitting drive energy to a driving device. The driving device is, for example, at least one wheel (or a propeller in the case of means of locomotion in water), which is set in rotation by the drive energy transmitted by the output shaft, whereby the means of locomotion moves. For example, the output shaft can be connected in a rotationally fixed manner to a traction gear, for example the chainring. This can be the case in particular when the drive unit is used as a mid-engine. Alternatively, the output shaft can also be designed in a rotationally fixed manner to a wheel, for example, in particular when the drive unit is used as a hub motor, wherein the output shaft then transmits the rotational movement, for example via spokes, to a driving device.The output drive shaft transmits its rotation to the propulsion system of the vehicle, which is why the drive unit is designed to impart a rotational force to the output drive shaft that corresponds to a desired travel speed of the vehicle. In the direction of force flow from the point of application of human muscle power, the output drive shaft is thus functionally arranged between the input drive shaft and the propulsion system driven by the drive unit.
[0010] Accordingly, the drive unit is designed to transfer the drive energy from the input drive shaft to the output drive shaft. At the same time, however, It is also provided that the drive unit is designed in such a way that it can adapt the rotational speed and the torque transmitted to the output drive shaft to the current requirements of the operating situation. For this purpose, the drive unit comprises a first electric motor drive unit with a drive shaft gear arranged around a rotational axis. The drive shaft gear comprises a first wave generator, a first flexspline, and a first ring gear. The rotational axis can, for example, be the pedal axle of a bottom bracket or the wheel axle of a driving device, in particular a driving device driven by the drive unit.
[0011] A wave gear is a type of gear that is particularly suitable for this application due to its simple and narrow design, robustness, and high reduction ratio. Wave gears themselves are described in the prior art and are known to those skilled in the art, for example, from DE 1 135 259 B. They can convert relatively high speeds with low torques of the wave generator into low speeds with high torques of the flexspline and / or the ring gear, and vice versa.
[0012] Furthermore, the first electric drive unit comprises a drive electric motor arranged around the rotational axis, comprising a stator and a rotor, wherein drive energy of the drive electric motor can be transferred to the output drive shaft via the drive shaft gear. The stator can, in particular, be mounted stationary relative to the support structure. The drive electric motor can therefore be used to assist the driver or their human muscle power by transferring drive energy provided by the electric motor to the output drive shaft and thus contributing to the propulsion of the means of transport. Due to the comparatively high reduction ratio of the shaft gear, the high speeds and low torques of the electric motor can be converted into low speeds with high torques, which can be used to drive the means of transport.For this purpose, the drive electric motor is preferably operatively connected to the wave generator of the drive shaft gear or is driven by it. In other words, the rotor of the drive electric motor is preferably connected to the wave generator in a rotationally fixed manner or even formed integrally with it. In this case, the output of the drive shaft gear is not formed by the ring gear, but by the first flexspline or by an element that is connected to the first flexspline in a rotationally fixed manner at least in one direction of rotation. The first flexspline or this element can be connected to the first flexspline in a rotationally fixed manner at least in one direction of rotation, in particular in both directions of rotation. The ring gear of the drive shaft, on the other hand, is fixed to the supporting structure or is even formed directly by the supporting structure itself.
[0013] In addition, the drive unit according to the invention has, as a second electric motor drive unit, a variable-gear drive with a second wave generator, a second flexspline, and a ring gear arranged in the drive train between the input drive shaft and the output drive shaft. The drive unit according to the invention thus simultaneously comprises two wave gears, which can, however, perform different functional tasks, as explained in more detail below. The variable-gear drive is arranged in such a way that it absorbs the drive energy of the input drive shaft, originating from human muscle power, and transmits it to the output drive shaft of the drive unit. Specifically, for this purpose, the input drive shaft is connected in a rotationally fixed manner (for example, via a freewheel, which will be explained in more detail later, or completely rotationally fixed) to the comparatively slow-rotating ring gear of the variable-gear drive.The drive energy derived from human muscle power is thus transferred via the ring gear to the flexspline of the variable-gear wave drive, which meshes with the ring gear. This second flexspline of the drive unit, in turn, is functionally connected to the first flexspline, in particular, is connected to it in a rotationally fixed manner and thus also to the output drive shaft in the manner described above. The summation of the drive energy of the first and second wave drive is thus achieved via a rotationally fixed connection between the two flexsplines and the output drive shaft, acting at least in one direction of rotation. This rotationally fixed connection can be direct or indirect, as described in more detail below.
[0014] The second electric motor drive unit comprises a variable speed electric motor with a stator and a rotor, the drive energy of which can also be introduced into the variable speed wave gear. This arrangement enables the combined energy from human muscle power and the variable speed electric motor to be transferred to the output drive shaft via the variable speed wave gear. This includes both the case where additional energy is added to the incoming energy from human muscle power towards the output drive shaft, and the case where the variable speed electric motor counteracts the incoming energy generated from human muscle power and thus draws drive energy towards the output drive shaft. In particular, the variable speed electric motor is operatively connected to the wave generator of the variable speed wave gear. For example, the rotor of the variable speed electric motor is designed to be rotationally fixed to the wave generator. The drive energy provided by the variable speed electric motor is therefore also transferred via the wave generator to the flexspline of the variable speed drive and further in the output direction, in particular to the output shaft. The variable speed drive translates the speed ratio from the input drive shaft to the output shaft and / or sums the drive energy from human muscle power and that from the variable speed electric motor. The variable speed drive and / or the variable speed electric motor are preferably arranged around the rotational axis, resulting in a compact design with advantageous power flow.
[0015] According to the invention, the first ring gear, i.e., the ring gear of the drive shaft gear, is arranged in a fixed position relative to the support structure of the drive unit. This can be achieved, for example, by the internal toothing of this ring gear being formed directly by the support structure itself, or, for example, by the ring gear being mounted as a separate component in a fixed position relative to the support structure or being connected to it. This ring gear can thus form a support point for the shaft gear of the first electromotive drive unit, i.e., the drive shaft gear.
[0016] The second ring gear, i.e., the ring gear of the second electric motor drive unit or the variable-frequency wave gear, is mounted and arranged so as to be rotatable about a rotational axis relative to the support structure, unlike the first ring gear. This means that the relative rotational position of the two ring gears changes about the rotational axis during operation of the drive unit.
[0017] Furthermore, the first flexspline, the second flexspline, and the output drive shaft are configured as a unit that is rotationally fixed or acts in a rotationally fixed manner relative to one another at least in one direction of rotation about the rotation axis. These units are thus connected or can be connected to one another for rotation about the rotation axis, such that the first flexspline and the second flexspline transmit the combined drive energy from human muscle power, the drive electric motor, and the variable speed electric motor to the output drive shaft. Thus, the output from both wave gears occurs via the respective flexsplines or via one or more elements that are rotationally fixed, in particular integrally formed, with the respective flexspline, as described in more detail below.
[0018] Overall, this arrangement enables an even more compact design of the drive unit compared to known solutions, particularly in the axial direction of the output drive shaft.
[0019] Compared to the supporting structure, the drive shaft gear and the variable-frequency shaft gear comprise various elements that can rotate around the rotational axis. Ideally, the drive unit is designed such that the rotating elements of the drive shaft gear, the variable-frequency shaft gear, the input drive shaft, and the output drive shaft are rotatable around the rotational axis or are arranged coaxially with each other with respect to their individual rotational axes.
[0020] There are many possible variations with regard to the specific design of the drive unit. For example, it is advantageous if the first flexspline and the second flexspline are each designed in the form of a flexspline pot or a flexspline hat. Each flexspline can comprise a sleeve region, inside which the respective wave generator is arranged and in contact with the flexspline. The external toothing of the flexspline can run on the outside of this region and engages with the respective internal toothing of the corresponding ring gear. This sleeve region can be followed by a transmission region which, viewed in the axial direction, can also have non-toothed or untoothed regions. This transmission region can be widened at least partially in the radial direction to the axis of rotation and thus extend outwards in the radial direction.This makes it possible to obtain an overall hat-like structure which has an essentially cylindrical region and a disk-like region adjoining this cylindrical region and extending outwards in the radial direction away from the axis of rotation, for example in the manner of a hat brim or rim. This design is referred to as a flexspline hat. Alternatively, however, the disk-like region can also extend inwards in the radial direction to the axis of rotation, thereby obtaining an essentially pot-like overall structure. This is also referred to as a flexspline pot. Based on this, it can now be provided that the first and the second flexspline are each designed as a radially flexible sleeve in the region of their toothing. The transmission region can additionally or alternatively each have a region of a transmission sleeve adjoining it in the axial direction.Furthermore, or alternatively, it can be provided that the first and / or the second flexspline each have a flexspline extending in the radial direction of the rotation axis of the respective flexspline. A transmission base plate in the case of the flexspline cup or a transmission cap edge plate in the case of the flexspline cap. The first and second flexsplines are preferably arranged offset from one another along the rotation axis such that the transmission base plates or the transmission cap edge plates face one another and the toothing regions face away from one another. As a result, the two ring gears are spaced apart from one another in the axial direction of the rotation axis and are arranged spatially separate from one another within the drive unit. In the axial direction of the rotation axis, in particular, the transmission base plates and / or transmission cap edge plates are positioned between the two ring gears, thus enabling an extremely compact overall arrangement.
[0021] It is preferably provided that the first and / or second flexspline are arranged in the drive train in such a way that the output of the first and / or second flexspline to the output shaft is effected via the respective transmission sleeve and / or the transmission base plate. Ideally, both the first and second flexspline each have either a transmission sleeve or a transmission base plate.
[0022] It may be advantageous if a flexspline connection is present that is designed such that it connects the first and second flexsplines to one another in a rotational direction about the rotational axis, at least indirectly, in a rotationally fixed manner, in particular such that it connects them to one another in a rotationally fixed manner, acting equally in both directions. If this is the case, it is advantageous if the flexspline connection is positioned such that it is located along the rotational axis or in the axial direction of the rotational axis between the drive electric motor and the variable electric motor, or between the variable electric motor and the axial end of the support structure along the rotational axis in a direction facing away from the drive electric motor.
[0023] The flexspline connection can extend in the radial direction to the rotation axis up to the radial height of the variable speed electric motor and / or the drive electric motor. It can be provided that the flexspline connection extends in the radial direction to the rotation axis up to a height of the first and / or second wave generator and / or the stator and / or rotor of the drive electric motor and / or the variable speed electric motor.
[0024] The connection and design of the two flexsplines is preferably also carried out in such a way that a radially extending to the rotation axis and the rotation axis A completely circumferential annular gap is present between an inner wall of the supporting structure, in the direction away from the inner wall, and the flexspline connection. This means that the two flexsplines and the flexspline connection end in the radial direction toward the rotation axis without contact with any other element in this area, so that freedom of movement in the radial direction is maintained, particularly in the area of the flexspline connection. The radial extent of the annular gap is preferably a maximum of 3 mm, in particular a maximum of 2 mm.
[0025] Furthermore, there are further design alternatives regarding the specific configuration of the flexspline connection. For example, it is possible for the first and second flexsplines, particularly in the area of their transmission disks, to be directly connected to one another, for example, by a material bond, such as by being glued, welded, or soldered together. One or more additional form-locking elements may also be present for the connection, for example, including connecting elements, particularly riveted or screwed connections. In the case of form-locking connections, it is preferred if these form-locking effects not only occur in the circumferential direction around the rotational axis, but also simultaneously in the axial direction of the rotational axis.As an alternative to a direct connection of the two units forming the first and second flexspline to one another, it is also possible to provide at least one additional connecting element via which the two flexsplines are indirectly connected to one another, in particular in a rotationally fixed manner. For this purpose, a connecting disk can be included, for example, which indirectly connects the first and second flexsplines, in particular in the region of their respective transmission base disks, to one another to obtain an overall unit that is rotationally fixed in at least one direction, in particular on their opposing annular disk surfaces. Here, too, it is possible for the connecting disk to be directly connected to the two flexsplines, for example by means of a material fit, in particular by means of an adhesive, welded or soldered connection, and / or by means of a form-fitting connection using suitable connecting elements.Here too, it is advantageous if the positive connection obtained is rotationally fixed at least in one direction of rotation around the axis of rotation, preferably in both directions of rotation, and / or additionally provides axial locking in the axial direction of the axis of rotation. Additionally or alternatively, at least one freewheel can be provided between the respective transmission disk and the connecting disk, so that a positive connection exists in one direction of rotation and not in the opposite direction of rotation or the positive connection is canceled depending on the direction of rotation. Additionally or alternatively, it can also be advantageous if a positive locking device acting in the direction of rotation of the axis of rotation with at least one relative to each other. Partially complementary form-fitting elements are present on the first and second flexspline, such as spur gearing or a screwable connecting flange. In this way, even partially direct power transmission from the first and / or second flexspline to the connecting disc and / or to the output can be achieved.
[0026] According to the invention, the drive energy is summed downstream of the two flexsplines in the output direction, for example, via the aforementioned connecting disk. An output sleeve may be provided that connects the first and / or second flexspline or the connecting base disk or the connecting cap edge disk to the output shaft. In addition to the sleeve encompassed, for example, by the first and second flexspline, this output sleeve thus represents a further sleeve structure that may, for example, be substantially hollow-cylindrical in shape, and whose cylinder wall is ideally spaced further radially from the axis of rotation than the first and / or second flexspline. Additionally or alternatively, the drive electric motor or the variable speed electric motor may be positioned in an interior space of the output sleeve.Viewed in the axial direction of the rotation axis, the output sleeve and the drive or variable speed electric motor are thus at least partially at the same height, and the drive or variable speed electric motor are completely orbited by the output sleeve in the radially outward direction. Additionally or alternatively, the first and / or second ring gear can be positioned in an interior space of the output sleeve. In this further development, too, it can therefore be provided that, viewed in the axial direction of the rotation axis, the output sleeve and the first and / or second ring gear are thus at least partially at the same height, and thus the first and / or second ring gear are completely orbited by the output sleeve in the radially outward direction. The resulting nested structure of the respective elements also leads to extremely efficient use of installation space and thus to a comparatively compact drive unit overall.
[0027] To further increase the functionality of the drive unit, it can be provided that the second ring gear is coupled to the input drive shaft via a freewheel in at least one direction. The freewheel, for example in the form of a sprag clutch, thus enables a rotationally fixed connection between the second ring gear and the input drive shaft, depending on the current relative direction of rotation of these two elements. to each other, which can further increase the ease of use of the drive unit for the user.
[0028] The second ring gear can be mounted directly on the input drive shaft or on an element connected to the input drive shaft in a rotationally fixed manner via at least one bearing point, for example, via a suitable ball bearing rotating around the rotation axis. Direct support of the second ring gear relative to the support structure is then unnecessary. This single bearing point can be sufficient to support this ring gear relative to the support structure in both the radial and axial directions of the ring gear's rotation axis.
[0029] With regard to the first ring gear, i.e. the ring gear of the drive shaft gear, it is possible that it extends with its internal toothing in the axial direction of the rotational axis in such a way that the internal toothing is located exclusively in a region of the drive unit that extends from the drive electric motor in the direction of the rotational axis in the opposite direction to the variable speed electric motor. Viewed in the axial direction from the drive electric motor, the internal toothing is thus located on the side of the drive electric motor facing away from the variable speed electric motor. In addition or alternatively, with regard to the second ring gear, i.e.The ring gear of the variable wave gear, for example, can extend with its internal toothing in the axial direction of the rotation axis in such a way that it lies exclusively in a region of the drive unit which, starting from the variable electric motor, extends in the direction of the rotation axis in the opposite direction to the drive electric motor. Viewed in the axial direction from the variable electric motor, the internal toothing is thus located on the side of the variable electric motor facing away from the drive electric motor. With regard to the two electric motors as a whole, the two internal toothings of the ring gears are thus located on opposite sides of this motor package consisting of the drive and variable electric motors, viewed in the axial direction of the rotation axis. In particular, for this arrangement too, it can be preferred if the flexspline connection is positioned between the two electric motors, viewed in the axial direction to the rotation axis.
[0030] In the axial direction of the rotation axis, the components "first ring gear / internal toothing of the first ring gear - drive electric motor - flexspline connection - variable speed electric motor - second ring gear / internal toothing of the second ring gear" are preferably arranged next to one another in this order. It can be provided that the stator of the variable speed electric motor and the stator of the drive electric motor are arranged in the axial direction of the rotation axis in the region between the first and second ring gear.
[0031] A further aspect of the invention relates to the unit superior to the drive unit according to the invention, specifically a means of transport with a drive unit according to the invention that can be driven simultaneously by human muscle power and drive energy provided by an electric motor. Such a means of transport can be designed, in particular, as a single-, double-, or three-track vehicle, in particular an electric bicycle, pedelec, e-bike, cargo bike, cargo bike, or transport bike.
[0032] The means of transport according to the invention can have multifaceted alternative development features. For example, it can be provided that it comprises a frame, in particular with a top tube and / or a down tube, wherein the frame can in particular have a known overall structure, as is customary, for example, for single-, two-, or three-track vehicles, in particular electric bicycles, pedelecs, e-bikes, cargo bikes, cargo bikes, or transport bikes. The means of transport can additionally or alternatively comprise an electrical energy storage device, in particular arranged in a top tube and / or down tube. It can further additionally or alternatively, in particular exclusively, have a front wheel and a rear wheel.The drive unit can be used in the form of a hub motor to drive one or more of the front or rear wheels. In this case, the support structure of the drive unit can form the hub, and the output shaft can be designed like a housing and can be connected in a rotationally fixed manner to the running surface of the respective wheel, for example via spokes and a rim. If, on the other hand, the drive unit is used as a mid-engine, the support structure is mounted in a rotationally fixed manner relative to the frame of the means of transport, in particular directly on the frame of the means of transport, with the input drive shaft in this case preferably being designed as a crankshaft. The means of transport can also have a steerable front or rear wheel and a non-steerable rear or front wheel, with the non-driven wheel preferably being the wheel driven by the drive unit.
[0033] The means of locomotion may comprise manually operable means for receiving and transmitting drive energy provided by human muscle power to the drive unit, such as, in particular, pedals that are designed to be rotatable about a pedal axis via crank arms and that are, in particular, rotationally fixedly connected to the input drive shaft. The pedal axis may run coaxially to the rotation axis of the drive unit, in particular when the drive unit in the means of transport is installed in the form of a mid-engine.
[0034] The invention is explained in more detail below with reference to the exemplary embodiments shown in the figures. They show schematically: Figure 1 is a side view of a means of transport with a central drive unit; Figure 2 is a side view of a means of transport with a hub drive unit; Figure 3 is an external view, in particular a plan view, of the central drive unit; Figure 4 is an external view, in particular a top view, of the hub drive unit; Figure 5 shows a cross section through a wave gear; Figure 6 is a sectional view along the rotation axis through the center drive unit; and Figure 7 is a sectional view along the rotation axis through the hub drive unit.
[0035] Identical or functionally identical components are designated with the same reference numerals in the figures. Recurring components are not always identified separately in each figure.
[0036] Figures 1 and 2 each show, by way of example, a means of transport F, specifically a bicycle, in particular an e-bike or pedelec. It can be powered simultaneously by an electric motor and human muscle power, in particular in such a way that the drive from human muscle power is assisted by an electric motor drive unit 1. The means of transport F comprises, in a known manner, a frame 3 and two driving devices 3, specifically a front wheel and a rear wheel. In the middle and at the lower end of the frame 2 is a pedal axle 4. The wheel axle 5 is located at the connection point between the frame 2 and the rear wheel. Figure 1 shows an embodiment in which the drive unit 1 is designed as a mid-drive unit or mid-motor and is located on the pedal axle 4. Human muscle power is introduced into the drive unit 1 directly via a pedal-operated crankshaft.The transmission output of the drive unit 1 is designed as a traction gear 6, for example as a chainring, and is connected to a rear wheel hub 8 via a traction means 7, for example a chain or a toothed belt. In the embodiment according to Figure 2, the drive unit 1 is designed as a hub drive unit and is mounted on the wheel axle 5 or The hub axle is arranged, or the supporting structure of the drive unit can form the hub axle itself. The transmission output of the drive unit 1, or the output drive shaft, is designed like an external housing in this case. Via this cylindrical output formation, which surrounds the hub, the output-side rotational movement can be transmitted to the rear wheel via spokes 9 (only shown as an example in Fig. 2). The drive unit 1 is connected to the bottom bracket 4 via the traction mechanism 3, through which human muscle power is transferred to the drive unit 1.
[0037] Figures 3 and 4 each show a plan view of the drive units 1 of Figures 1 and 2 from the outside, specifically Figure 3 shows the drive unit 1 as a mid-engine arrangement and Figure 4 shows the drive unit 1 as a hub motor arrangement.
[0038] In the mid-motor arrangement according to Fig. 3, the rotational axis 10 of the drive unit 1 lies on the pedal axis 4, around which the crank arms 11 and the pedals 12 of the means of transport F rotate during a pedaling movement by an operator. The traction gear 6 serves to transmit the rotational movement to the rear wheel. The width of the drive unit 1 is designated B1. The distance between the crank arms 11 is designated B2. To enable comfortable pedaling of the pedals 6 that is adapted to the human anatomy, the distance B2 of the crank arms 11 along the rotational axis should be between 140 mm and 180 mm. The width B1 of the drive unit 1 should therefore be correspondingly smaller. In addition, Figure 3 shows an optional control unit 13 that can be integrated into the drive unit 1.The control unit 13 can be connected to a plurality of sensors to detect, monitor, and optionally control the operating state of the drive unit 1 and the means of transport F. Furthermore, the control unit 13 can be connected to a display unit 14, for example, an illuminated display, which is visible from outside the drive unit 1. For example, the display unit 14 is arranged behind a viewing window in the outer housing of the drive unit 1.
[0039] Fig. 4 shows an embodiment of the drive unit 1 as a hub drive unit. The rotational axis 10 of the drive unit 1 lies on the wheel axle 5, around which the rear wheel rotates while the means of transport F is traveling. Rotation originating from the pedals 12 of the means of transport F is transmitted to the drive unit 1 via the traction gear 6. While the drive unit 1 as a center drive unit is penetrated by a rotating crankshaft 15 (see Figure 6), as a hub drive unit it is penetrated by a stationary axle body 16 (see Figure 7), around which the rear wheel rotates. A housing-like outer structure (hub shell) serves as the transmission output and thus as the output drive shaft 35. It rotates around the axle body 16 and is non-rotatably connected to the spokes 9. The spokes 9, in turn, transmit the rotational movement to the rest of the rear wheel.
[0040] Figure 5 shows a cross section through a wave gear 19a, 19b as used in the invention and is intended to explain roughly schematically the basic functional principle of a wave gear. The wave gear 19a, 19b is arranged around the rotation axis 10 and comprises a wave generator 20a, 20b, a pivot bearing 21a, 21b, in particular a deep groove ball bearing, a flexspline 22a, 22b and a ring gear 23a, 23b. In the following further description of specific embodiments, it will be explained that the drive unit 1 has a drive wave gear 19a and a variation wave gear 19b. The elements designated by the reference numerals 20a, 21a, 22a and 23a are assigned to the drive wave gear 19a. The elements designated by the reference numerals 20b, 21b, 22b and 23b are assigned to the variation wave gear 19b. The design features described for Fig. 5 relate to both the drive wave gear 19a and the variation wave gear 19b.
[0041] Elements labeled "a" belong to the drive shaft gear, and elements labeled "b" belong to the variable-frequency shaft gear. The ring gears 23a / 23b and the shaft generators 20a / 20b are designed as rigid components, while the flexsplines 22a / 22b are flexible or elastic. The shaft generators 20a / 20b are oval in shape, and the flexsplines 22a / 22b are mounted on the respective shaft generators 20a / 20b via the pivot bearings 21a / 21b in such a way that the flexsplines 22a / 22b adapt to the oval shape of the respective shaft generators 20a / 20b due to their elasticity. The ring gears 23a / 23b have an internal toothing and the flexsplines 22a / 22b have a partially complementary external toothing, whereby the flexsplines 22a / 22b typically have fewer teeth than the respective ring gear 23a / 23b.Due to the oval shape of the wave generators 20a / 20b, the external teeth of the respective flexspline 22a / 22b are pressed along the main axis of the respective wave generator 20a / 20b into the internal teeth of the respective ring gear 23a / 23b. At the same time, the elastic deformation of the flexsplines 22a / 22b ensures that their external teeth along the minor axis of the respective wave generator 20a / 20b are disengaged from the internal teeth of the respective ring gear 23a / 23b. If the wave generator 20a / 20b now rotates, the respective flexspline 22a / 22b rotates in the opposite direction with a reduction ratio of i = zH / (zH - zF), where zH is the number of teeth of the respective ring gear. 23a / 23b and zF is the number of teeth of the respective flexspline 22a / 22b. For example, if the flexspline 22a / 22b is held in place, the ring gear 23a / 23b rotates at the correspondingly reduced speed in the same direction as the wave generator 20a / 20b. If the ring gear 23a / 23b is held in place, the flexspline 22a / 22b rotates at the correspondingly reduced speed opposite to the direction of rotation of the wave generator 20a / 20b. Such wave gears 19a, 19b are summation gears and their basic mode of operation is known in the art. To drive the wave gears 19a / 19b, an electric motor 24a / 24b can be provided, via which the rotary movement of the respective wave generator 20a / 20b is achieved. Each of the electric motors 24a / 24b comprises a rotor 25a / 25b and a stator 26a / 26b. The rotor 25a / 25b is connected to the respective wave generator 20a / 20b it drives. The stator 26a / 26b, however, is stationary relative to the support structure 18 (Fig.6 at the same time the essential outer casing; Fig. 7 at the same time the hub bearing axis 17).
[0042] Figures 6 and 7 show cross-sectional views through a drive unit 1 in the vertical direction and along the respective rotation axis 10. Figure 6 shows a mid-mounted motor. Figure 7 shows a hub motor.
[0043] A possible basic structure of the drive unit 1 and its possible mode of operation are first explained in more detail with reference to Fig. 6. Fig. 6 thus shows a drive unit 1 as already presented in Figs. 1 and 3.
[0044] In the present exemplary embodiment, the support structure 18 of the drive unit 1 is intended for stationary mounting on the frame 2 of a means of transport F, as illustrated by way of example in Fig. 6 with the arrow pointing to a frame 2. The support structure 18 not only represents a housing-like protection for the transmission components described in more detail below, but is also the essential support structure during operation of the transmission components movable relative thereto. The drive shaft gear 19a and the variable-frequency shaft gear 19b are arranged in the interior of the support structure 18. The ring gear 23a of the drive shaft gear 19a is arranged stationary relative to the support structure 18 and can, for example, either be formed by the support structure 18 itself or be firmly connected to it, for example by pressing the ring gear of the ring gear 23a into a suitable, prefabricated receiving formation of the support structure 18.In contrast, the ring gear 23b of the variation wave gear 19b is rotatable about the rotation axis 10 relative to the support structure 18.
[0045] The drive energy provided by the electric motor 24a for the propulsion of the means of transport F thus sets the wave generator 20a in a rotary motion via the interaction between the rotor 25a and the stator 26a. The wave generator 20a thereby rotates around the rotation axis 10 and is mounted in the pivot bearing 21a and in another pivot bearing 27. The two pivot bearings 21a and 27 can both be located on a common bearing plane E1, which extends radially to the rotation axis. Due to the action of the wave generator 20a already described above, the flexspline 22a is also set in a rotary motion around the rotation axis R, because the corresponding ring gear 23a is rotationally fixed relative to the support structure 18.
[0046] In addition to the external toothing engaging the internal toothing of the ring gear 23a, the flexspline 22a comprises a transmission region in the form of a hollow cylindrical transmission sleeve 28a extending in the axial direction of the rotation axis toward the electric motor 24a. This transmission sleeve extends in the axial direction along the rotation axis 10 in the direction away from the external toothing of the flexspline 22a, past the electric motor 24a, and up to a transmission base plate 29a, so that the flexspline 22a is designed as a flexspline cup overall.
[0047] Drive energy provided by human muscle power is applied via the crank arms 11 (with manually operable actuating means not shown in detail in Fig. 6, such as the aforementioned pedals) and fed to the drive unit 15 via the crankshaft 15, which is non-rotatably connected to the crank arms 11 and acts in this case as the input drive shaft. For this purpose, a receiving ring 30 is provided, which is arranged inside the drive unit 1 and non-rotatably connected to the crankshaft 15. This receiving ring 30 can be permanently non-rotatably connected or, as shown in Fig. 6, selectively connected or operatively connected to the ring gear 23b via a freewheel 31 in a drive direction of rotation of the crankshaft 15. The ring gear 23b of the variable-frequency wave gear 19b, unlike the ring gear 23a of the drive shaft gear 19a, is rotatable relative to the support structure 18.If the crankshaft 15 is set in rotation in the drive direction by the operator of the means of transport F, the ring gear 23b also rotates about the rotation axis 10. This rotational movement is transmitted to the flexspline 22b of the variable wave gear 19b. The flexspline 22b comprises, in a manner comparable to the flexspline 22a, a transmission sleeve 28b and a transmission base plate 29b, wherein in this case the transmission sleeve 28b extends in the axial direction along the rotation axis 10 in the direction from the. The external toothing of the flexspline 22b extends beyond the electric motor 24b to a transmission base plate 29b. In this case, too, the flexspline 22b is thus designed as a single flexspline pot. The two flexspline pots 22a and 22b are arranged with their respective pot bottoms in the form of the transmission base plate facing each other along the rotation axis 10. By operating the variable-speed electric motor 24b, it is possible to modify or vary the output rotary motion of the flexspline 22b relative to the drive-side rotary motion of the crankshaft 15 or the ring gear 23b.
[0048] The two flexsplines 29a and 29b are connected to each other on the output side in a rotationally fixed manner at least in one direction of rotation, preferably permanently connected to each other in both directions of rotation about the rotation axis. In the specific embodiment, the two flexsplines 29a and 29b are not directly connected to each other, which is also encompassed by the invention, but indirectly by means of a connecting disk 32, to whose opposite end faces one of the two transmission base disks 29a and 29b is fastened, for example, by a material fit and / or form fit.The connecting disc 32 can be designed as a ring disc and can extend, for example, in the radial direction from the axis of rotation in an area starting from a height of the pivot bearing 27 in an outward direction up to above the height of one or both of the electric motors 23 a and 24 b and even above the height of at least one of the ring gears 23 a and 23 b, in particular above the height of both ring gears 24 a and 23 b.
[0049] The connecting disc 32 is rotationally fixedly connected to an output sleeve 33. This sleeve can extend in the direction of the rotation axis 10 or in the axial direction, for example, over the variable speed electric motor 24b and also the variable speed wave gear 19b, and comprises, at its end opposite the connecting disc 32, an output base disc 34 that terminates in an output shaft 35. The output shaft 35 can be coupled, for example, to a sprocket of a traction drive (not shown in Fig. 6).
[0050] Thus, viewed in the axial direction of the rotation axis, an arrangement can be achieved, for example, in which the output shaft 35, the output base plate 34, the receiving ring 30, the variable speed electric motor 24b, the transmission base plates 29a and 29b with the connecting plate 32 located therebetween, the drive electric motor 24a and the rotary bearing 27 can be positioned next to one another and one after the other in this order, whereby a comparatively compact overall arrangement is possible.
[0051] There is also a large scope for variation with regard to the required bearing planes E running radially to the axis of rotation 10, whereby the present exemplary embodiment has the bearing plane E1, in which the two pivot bearings 21a and 27 are arranged. A further bearing plane E2 comprises the two pivot bearings 21b and 36, whereby the pivot bearing 36 is comparable to the pivot bearing 27. Two bearing planes are present, the bearing planes E3 and E4, which serve to support the crankshaft 15 and which, viewed in the axial direction of the axis of rotation 10, are located in the opposite side edge regions of the drive unit 1. In the bearing plane E3, the support structure 18 is mounted relative to the crankshaft 15 via the pivot bearing 37. In the bearing plane E4, on the other hand, there are the two pivot bearings 38 and 39, which, spaced apart from each other in the radial direction, support the crankshaft 15 relative to the output shaft 35 and the output shaft 35 relative to the support structure 18.Finally, a further pivot bearing 38 is provided in the bearing plane E5, via which the ring gear 23b is supported relative to the crankshaft 15. Thus, the ring gear 23b itself comprises practically exclusively the pivot bearing 38 for support.
[0052] The entire formation of the two flexsplines 22a and 22b can be axially secured in the axial direction of the rotation axis 10 exclusively via the one bearing plane E4. In particular, it is not necessary to support the two flexsplines 22a and 22b in their connection area, in particular including a potentially present connecting disk 32, in the radial direction on the support structure. Quite the opposite. The exemplary embodiment in Fig. 6 illustrates that an annular gap 39 completely encircling the rotation axis 10, viewed outward in the radial direction, can be provided between the support structure 18 or a part stationary relative to the support structure 18 and the flexsplines 22a and 22b at the axial height of their transmission base disks 29a and 29b as well as at the axial height of the connecting disk 32.
[0053] Finally, Fig. 7 illustrates the integration of a drive unit according to the invention as a hub motor. Essentially, reference is made to the previous information, particularly to Fig. 6, and only a few of the essential differences are highlighted.
[0054] Unlike the variant according to Fig. 6, in Fig. 7 the drive energy provided by human muscle power is not supplied via the crankshaft 15, but via an input drive shaft 15', which is connected, for example, to an output flange of a traction mechanism or the like, which in turn can be actuated by muscle power. This input shaft is mounted relative to the frame-fixed hub bearing axle 17 or the rotatably mounted on a support structure 18 which is rotatably and stationary relative to a potential mounting frame of the means of transport via the pivot bearings 36 and 37. The design of the output of the drive unit 1 differs from the exemplary embodiment according to Fig. 6. Instead of the output shaft 35 projecting laterally in the axial direction, an outer housing-like or hollow cylindrical output shaft 35 is provided in the present case, which closes off the drive unit 1 to the outside in the radial direction to the axis of rotation 10 and which is connected to the wheel to be driven directly or indirectly, for example via spokes in a manner known per se.
[0055] A further difference is that no output sleeve 33 and no output base plate 34 are required, since the output does not have to be led out of the drive unit 1 to the side in the axial direction, but only in the radial direction onto the radially outer output shaft 35, which in this case, for example, is designed essentially like an outer housing. For this purpose, only the preferably flat connecting plate 32 is required. The connecting plate 32 can be connected to one of the transmission base plates 29a and 29b on its two opposite annular disc sides, as shown in Fig. 7. The connecting plate 32 can be connected to the output shaft 35 in a rotationally fixed manner with its outer edge side in the radial direction to the rotation axis or in the outer edge region of its annular disc sides in the radial direction.
[0056] The freewheel 31 is optional. It is also possible for the input shaft 15' to form a single, non-rotatable unit with the ring gear 23b in both directions of rotation, even as a single component.
Claims
PATENT CLAIMS 1. Drive unit (1) for a means of locomotion (F) that can be driven simultaneously by human muscle power and by an electric motor, comprising - a supporting structure (18), - an input drive shaft (15, 15') for transmitting drive energy generated from human muscle power, - an output shaft (35) for delivering drive energy to a driving device (3), - a first electric motor drive unit with - a drive shaft gear (19a) with a first shaft generator (20a), a first flexspline (22a) and a first ring gear (23a), - a drive electric motor (24a) with a stator (26a) and a rotor (25a), wherein drive energy of the drive electric motor (24a) can be transmitted to the output drive shaft (35) via the drive shaft gear (19a), - a second electric motor drive unit with - a variation wave gear (19b) arranged in a drive train between the input drive shaft (15, 15') and the output drive shaft (35) with a second wave generator (20b), a second flexspline (22b) and a second ring gear (23b), - a variable speed electric motor (24b) with a stator (26b) and a rotor (25b), the drive energy of which can be introduced into the variable speed drive (19b), the variable speed drive (19b) being arranged such that it transmits the combined energy from human muscle power and the variable speed electric motor (24b) to the output drive shaft (35) of the drive unit (1), characterized by - that the first ring gear (23a) is arranged stationary relative to the supporting structure (18) of the drive unit (1), - that the second ring gear (23b) is arranged to be rotatable about a rotation axis (10) relative to the support structure (18), - and that the first flexspline (22a), the second flexspline (22b) and the output drive shaft (35) are connected to one another in a rotationally fixed manner so as to be rotatable about the rotation axis (10), such that the first flexspline (22a) and the second flexspline (22b) transmit the summed drive energy from human muscle power, the drive electric motor (24a) and the variation electric motor (24b) to the output drive shaft (35).
2. Drive unit (1) according to claim 1, characterized in that the rotating elements of the drive shaft gear (19a), the variation shaft gear (19b), the input drive shaft (15, 15') and the output driven shaft (35) are rotatable about the rotation axis (10).
3. Drive unit (1) according to one of the preceding claims, characterized in that the first flexspline (22a) and the second flexspline (22b) are each designed in the form of a flexspline pot or a flexspline hat and for this purpose - are each designed as a radially flexible sleeve in the region of their toothing, - each have an axially adjoining region of a transmission sleeve (28a, 28b) and - each have a transmission base plate (29a, 29b) in the case of the flexspline pot or a transmission hat edge plate in the case of the flexspline hat extending in the radial direction of the rotation axis (10) of the respective flexspline (22a, 22b), wherein the first and the second flexspline (22a, 22b) are arranged offset from one another along the rotation axis (10) in such a way that the transmission base plates (29a, 29b) or the transmission hat edge plates face one another and the areas of the toothings face away from one another.
4. Drive unit (1) according to claim 3, characterized in that the first and / or the second flexspline (22a, 22b) are arranged in the drive train in such a way that the output of the first and / or second flexspline (22a, 22b) to the output drive shaft (35) takes place via the transmission sleeve (28a, 28b) and / or the transmission base plate (29a, 29b).
5. Drive unit (1) according to one of the preceding claims, characterized in that along the axis of rotation (10) - between the drive electric motor (19a) and the variation electric motor (19b) or - a flexspline connection is provided between the variable electric motor (19b) and the axial end of the support structure (18) along the rotation axis (10), which flexspline connection is designed such that the first and second flexsplines (22a, 22b) are connected to one another in a rotationally fixed manner, at least indirectly, in a direction of rotation about the rotation axis (10).
6. Drive unit (1) according to claim 5, characterized in that the flexspline connection extends in the radial direction to the rotation axis (10) up to a height of the first and / or second wave generator (20a, 20b) and / or the stator (26a, 26b) and / or rotor (25a, 25b) of the drive electric motor (24a) and / or the variation electric motor (24b).
7. Drive unit (1) according to one of claims 5 or 6, characterized in that an annular gap (39) extending in the radial direction to the axis of rotation (10) and completely encircling the axis of rotation (10) is present between an inner wall of the support structure (18) in the direction away from the inner wall and the flexspline connection, wherein the radial extent of the annular gap (39) is a maximum of preferably 3 mm, in particular a maximum of 2 mm.
8. Drive unit (1) according to one of claims 5 to 7, characterized in that the flexspline connection has at least one of the following features: - the first and second flexsplines (22a, 22b) are directly connected to one another, in particular in the region of their transmission discs; - there is a connecting disc (32) which indirectly connects the first and second flexsplines (22a, 22b), in particular in the region of their transmission base discs (29a, 29b); - there is a form-locking device acting in the direction of rotation of the rotation axis (10) with form-locking elements which are at least partially complementary to one another on the first and on the second flexspline (22a, 22b).
9. Drive unit (1) according to one of the preceding claims, characterized in that an output sleeve (33) is provided which connects the first and / or the second flexspline (22a, 22b) or the connecting base plate (34) or the connecting cap edge plate to the output output shaft (35), wherein in particular - the drive electric motor (19a) or the variation electric motor (19b) are positioned in an interior of the output sleeve (33) and / or - the first and / or second ring gear (23a, 23b) are positioned in an interior of the output sleeve (33).
10. Drive unit (1) according to one of the preceding claims, characterized in that the second ring gear (23b) is coupled via a freewheel (31) relative to the input drive shaft (33) at least in one direction.
11. Drive unit (1) according to one of the preceding claims, characterized in that the second ring gear (23b) is mounted on the input drive shaft via at least one bearing point.
12. Drive unit (1) according to one of the preceding claims, characterized in that the first ring gear (23a) extends with its internal toothing in the axial direction of the rotation axis (10) in such a way that it lies exclusively in a region of the drive unit (1) which extends from the drive electric motor (19a) in the direction of the rotation axis (10) in the opposite direction to the variable electric motor (19b) and / or that the second ring gear (23b) extends with its internal toothing in the axial direction of the rotation axis (10) in such a way that it lies exclusively in a region of the drive unit (1) which extends from the variable electric motor (19b) in the direction of the rotation axis (10) in the opposite direction to the drive electric motor (19a).
13. Drive unit (1) according to one of the preceding claims, characterized in that the stator (26b) of the variable speed electric motor (19b) and the stator (26a) of the drive electric motor (26a) are arranged in the axial direction of the rotation axis (10) in the region between the first and the second ring gear (23a, 23b).
14. Means of transport (F) which can be driven simultaneously by human muscle power and drive energy provided by an electric motor, with a drive unit (1) according to one of the preceding claims, characterized in that it is designed as a single-, two- or three-track vehicle, in particular an electric bicycle, pedelec, e-bike, cargo bike, cargo bike or transport bike.
15. Means of transport (F) according to claim 14, characterized in that it has at least one of the following features: - it comprises a frame (2), in particular with a top tube and / or down tube; - it comprises an electrical energy storage device, in particular arranged in the top tube and / or down tube; - it includes a front wheel and a rear wheel; - it comprises a front wheel which is designed to be steerable; - it comprises pedals (12) which are designed to be rotatable about a pedal axis (4) via crank arms (11) and which are in particular connected in a rotationally fixed manner to the input drive shaft (15).