A drive unit for a vehicle that can be driven simultaneously by human muscle power and an electric motor

Abstract

The present invention relates to a drive unit (1) of particularly narrow construction for a means of transport (F) that can be driven simultaneously by human muscle power and by drive energy provided by the electric motors, comprising two strain wave gears (13, 18) and two electric motors (22, 27), and that is capable of transmitting the sum of the human muscle power and the drive energy provided by the electric motors (22, 27) to an output driven shaft (12).

Description

[Technical Field]

[0001] The present invention relates to a drive unit for a means of transport which can be driven simultaneously from human muscle power and by drive energy provided by an electric motor. [Background technology]

[0002] Mobility means of this type are, for example, vehicles with two or more wheels, such as bicycles, in particular electric bicycles, e-bikes or pedelecs, but also pedalos, pedal boats or wheelchairs. In particular, mobility means of this type are vehicles of vehicle classes L1e, L2e, L3e, L4e, L5e, L6e and L7e according to Article 4 of EU Regulation 2013 / 168 / EU of 15 January 2013. This also includes, in particular, vehicles with a maximum speed of up to 6 km / h depending on the type, vehicles dedicated to disabled persons, e.g., wheelchair users, vehicles dedicated to sports competitions, bicycles with pedal-assisted pedal drives equipped with an electric motor-assisted drive with a maximum continuous rated power of up to 250 W, in which the assistance is interrupted when the rider stops pedaling and progressively decreases as the vehicle speed increases, until the bicycle is stopped before the vehicle speed reaches 25 km / h, self-balancing vehicles with electric motor-assisted traction drives, sports vehicles with pedal drives, vehicles with pedal drives that do not have a seat, and vehicles with pedal drives with an R-point (according to ECE-R17) of ≦400 mm. In most cases, these vehicles have a front wheel and at least one rear wheel connected to each other via a frame. However, there can also be several rear wheels, e.g., two rear wheels, and / or several front wheels, e.g., two front wheels, in particular in any combination. They can also be arranged side by side in the forward direction of travel, or one behind the other in the forward direction of travel, e.g., in tandem, as in, for example, wheelchairs, tricycles, or vehicles with sidecars. Such vehicles are increasingly equipped with at least one electric motor that assists the user in propelling the vehicle. Typically, the vehicle is not driven solely by this electric motor, but rather the electric motor assists the user's own human muscle power in propelling the vehicle. In such cases, the degree of assistance is often selectable. In this way, the user generates as much power as possible or desired while traveling in such a vehicle, while still moving at a speed that is more comfortable and useful in everyday life.

[0003] In addition to assisting the user in driving the vehicle, it is also known to equip drive units for such vehicles with two electric motors and a totalizing gear. In this way, a continuously variable transmission (CVT) controlled by a control unit can be realized, for example. The operator then no longer needs to select the currently appropriate gear from a number of different available gears, as is the case, for example, with a conventional bicycle. Instead, the transmission ratio (speed ratio) appropriate for the current driving situation is continuously adjusted by the control unit by controlling at least one of the electric motors of the totalizing gear. Such drive units are known, for example, from EP 1 642 820 A1 and EP 2 218 635 A1. In these publications, a planetary gear is used as the totalizing gear.

[0004] A problem with conventional drive units is their structural size, particularly in the transverse direction relative to the longitudinal axis of the vehicle. Drive units are typically located on or near the wheel hub or on or near a drive unit bearing, such as a bottom bracket. On the one hand, the drive unit should not protrude excessively beyond the wheel on either side. On the other hand, when located on the bottom bracket, care must be taken to ensure that the crank arms of bicycle pedals, for example, adhere to a maximum axial distance of 140 to 180 mm, based on human anatomy. The drive unit, located between the crank arms, must be designed to be as narrow as possible to ensure comfortable riding even over long distances. However, this poses a number of design challenges, as the integral rotation bearings and the freewheel themselves each require a certain amount of space. The total gearing and electric motor also typically occupy significant installation space in the drive unit, particularly in the direction of the bottom bracket or rear wheel rotation axis, unnecessarily increasing the overall width of the drive unit. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] European Patent Application Publication No. 1642820 [Patent Document 2] European Patent Application Publication No. 2218635 Summary of the Invention [Problem to be solved by the invention]

[0006] The object of the present invention is therefore to provide a drive unit that is as narrow as possible, particularly transversely to the direction of travel of the vehicle, and at the same time, the drive unit should be flexibly controllable and cover the full functional range of modern drive units. [Means for solving the problem]

[0007] This solution is achieved by a drive unit according to the independent claim. Preferred developments are given in the dependent claims. Furthermore, the invention also extends to a means of transport comprising such a drive unit.

[0008] The drive unit according to the present invention comprises an input drive shaft for transmitting drive energy generated or provided by human muscle power. That is, the input drive shaft can be, for example, a bicycle crankshaft or can be non-rotatably connected thereto. Alternatively, the input drive shaft can be non-rotatably connected to a traction means gear, such as a chainring. The input drive shaft is thus arranged so that it can be rotated by the operator or driver of the means of transport using human muscle power, for example by pedaling a bicycle. This can be done directly or indirectly. In particular, it is intended that this be done in the direction of power flow from the point of input of human muscle power to the entire drive train, before the electric motor.

[0009] The drive unit according to the present invention includes an output driven shaft for transmitting drive energy to a propulsion device. The propulsion device, for example, at least one wheel (or a propeller in the case of an underwater vehicle), is rotated by the drive energy transmitted by the output driven shaft, thereby propelling the vehicle. For example, the output driven shaft can be non-rotatably connected to a traction device gear, such as a chain ring. Alternatively, the output driven shaft can be non-rotatably connected to a hub housing that transmits rotational motion to the propulsion device, for example, via spokes. The output driven shaft transmits its rotation to the propulsion device of the vehicle, and for this reason, the drive unit is configured to apply a rotation to the output driven shaft corresponding to the desired running speed of the vehicle. The output driven shaft is therefore operatively disposed between the input drive shaft and the propulsion device driven by the drive unit, in the direction of force flow from the point of application of human muscle force.

[0010] Thus, the drive unit is designed to transmit drive energy from an input drive shaft to an output driven shaft. However, it is also contemplated that the drive unit can be designed so that the rotational speed and torque transmitted to the output driven shaft can be adapted to the requirements of the current operating situation. For this purpose, the drive unit comprises a drive strain wave gearing having a first wave generator, a first flexspline, and an internal gear, arranged around a rotational axis. The rotational axis can be, for example, a pedal axle of a bottom bracket or a wheel axle of a running device, particularly a running device driven by the drive unit. Due to their simple, narrow design, robustness, and high reduction ratio, strain wave gearing is a type of gearing particularly suited for this application. Strain wave gearing itself is described in the prior art and is known to those skilled in the art, for example, from German Patent Application Publication No. 1135259. They can, for example, convert a low torque at a high rotational speed of the wave generator into a high torque at a low rotational speed of the flexspline and / or the internal gear, and vice versa. The drive unit further includes a drive electric motor arranged around a rotation axis together with a stator and a rotor, and the drive energy of the drive electric motor can be transmitted to an output driven shaft via a drive strain wave gearing. Thus, the drive electric motor can be used to supplement the driver's or his / her muscular strength by transmitting the drive energy provided by the electric motor to the output driven shaft and thereby contributing to the movement of the vehicle. The relatively high reduction ratio of the strain wave gearing allows the low torque at high rotational speeds of the electric motor to be converted into high torque at low rotational speeds that can be used to drive the vehicle. For this purpose, the drive electric motor is preferably operatively connected to the wave generator of the drive strain wave gearing. In other words, the rotor of the drive electric motor is preferably non-rotatably connected to the wave generator or even formed integrally therewith. In this case, it is preferred that the driven part of the drive strain wave gearing be formed by an internal gear. In particular, the internal gear is non-rotatably connected to the output driven shaft of the drive unit.

[0011] Furthermore, the drive unit according to the present invention comprises a variable wave gearing arranged in the drive train between the input drive shaft and the output driven shaft, the variable wave gearing having a second wave generator, a second flexspline, and an internal gear. Thus, the drive unit according to the present invention simultaneously comprises two wave gearings, which can perform different tasks in terms of their functions, as will be explained in more detail below. The variable wave gearing is specifically arranged to receive drive energy of the input drive shaft, which originates from human muscle power, and transmit it to the output driven shaft of the drive unit. For example, for this purpose, the input drive shaft is non-rotatably connected to a gearing member of the variable wave gearing, such as the flexspline or the internal gear, which rotates at a slower speed (e.g., via a freewheel, which will be explained in more detail later). Preferably, the input drive shaft is non-rotatably connected to the flexspline, and the drive energy originating from human muscle power is introduced or fed to the variable wave gearing via the flexspline. In this preferred embodiment, the internal gear is non-rotatably connected to the output driven shaft, and drive energy derived from human muscle power is transmitted to the internal gear via the flexspline, thereby driving the output driven shaft. Since the flexspline is permanently engaged with the internal gear by its teeth, the rotational speed of the input drive shaft is initially transmitted 1:1 to the output driven shaft. However, the transmission ratio (transmission ratio) between the input rotational speed via the flexspline and the output rotational speed via the internal gear can be influenced, for example, by using an additional wave generator. For this purpose, according to the invention, a variable speed electric motor is provided, in particular having a stator and a rotor arranged around the rotation axis, and its drive energy is also introduced into the variable wave gearing. This arrangement further makes it possible to transmit the combined energy of the human muscle power and the variable electric motor to the output driven shaft via the variable wave gearing. This includes both cases where additional energy is added to the incoming energy from human muscle power toward the output driven shaft, and cases where the variable electric motor interferes with the incoming energy generated from human muscle power, thereby subtracting drive energy toward the output driven shaft.In particular, the variable electric motor is operatively connected to the wave generator of the variable wave gearing. For example, the rotor of the variable electric motor is configured to be non-rotatable with respect to the wave generator. Therefore, the drive energy provided by the variable electric motor is transmitted via the wave generator to the internal gear of the variable wave gearing, and in particular to the output driven shaft. The variable wave gearing converts the rotation speed ratio of the input drive shaft to the output driven shaft and / or sums the drive energy from the human muscle power and the drive energy from the variable electric motor. The variable wave gearing and / or the variable electric motor are preferably arranged around the rotation axis, which results in a compact design with an advantageous power flow.

[0012] In the drive unit according to the present invention, the internal gear of the drive strain wave gearing and the internal gear of the variable strain wave gearing are configured to be non-rotatable relative to each other. This can be achieved by a connecting element, such as a locking pin or the like, that connects the two internal gears to each other non-rotatably. However, it is also possible, and preferred, for the two internal gears to be formed integrally with each other. Thus, in this embodiment, an internal gear unit is provided with two internal gears spaced apart from each other in the axial direction of the rotation shaft, sometimes for engagement with the first flexspline and sometimes for engagement with the second flexspline. The two internal gears can be axially separated from each other or can directly transition axially relative to each other. Configuring the two internal gears to be non-rotatable relative to each other allows the combined drive energy from the human muscle power, the drive electric motor, and the variable electric motor to be transmitted to the output driven shaft at this point. Therefore, the internal gear unit forms the sum point of the two strain wave gearings of the drive unit toward the output driven shaft. In particular, both internal gears have internal teeth that are complementary to the external teeth of the respective flexsplines (a characteristic of wave gearing is that the number of internal teeth of the internal gear is greater than the external teeth of the flexspline). The two wave gearings of the drive unit are therefore operatively connected to each other via this common internal gear. In particular, the two wave gearings use the common internal gear as the driven part or gearing output, so that the total drive energy or drive force resulting from the two electric motors and the human muscle power is applied to the internal gears and, likewise, to the output driven shaft. That is, according to a first core idea, the present invention uses two wave gearings, via which the total drive energy or drive force of the two electric motors of the means of transportation and the driver is transmitted to the operatively connected internal gears or to the common internal gear and from there to the output driven shaft. This allows the drive unit to be designed with a particularly narrow width.As mentioned above, using a common ring gear of two gear trains, or two ring gears that are configured so as not to rotate relative to one another, as a summing point and / or as a gear train output or gear train driven part basically serves to save axial installation space in any drive having two gear trains, in particular in the case of a motor configured as described above, as long as these can be driven via the ring gears, for example, regardless of the type of gear train used. This aspect therefore represents an independent and separate invention that, apart from the development of the concept specifically described in the present application, could be claimed separately, independently of the structural and functional features of the embodiments described herein.

[0013] The drive electric motor and / or the variable speed electric motor are preferably synchronous motors, in particular three-phase synchronous motors, preferably of the external rotor type, which in the embodiment described according to the invention are characterized by particularly narrow dimensions.

[0014] The variable electric motor can convert the rotational speed introduced by the driver via the input drive shaft to the output driven shaft in various ways depending on its direction of rotation. This conversion achieves a change in the speed of the output driven shaft relative to the input drive shaft. For example, the output driven shaft can be accelerated or braked relative to the input drive shaft, and the variable electric motor can maintain a set transmission ratio (gear ratio) for a long period of time without further acceleration or braking. This is preferably achieved by using a variable wave gearing, particularly in conjunction with the variable electric motor, to form a continuously variable transmission between the input drive shaft and the output driven shaft. By controlling the rotational speed of the variable electric motor, the rotational speed of the output driven shaft can be converted to any degree of acceleration or deceleration relative to the input drive shaft. Therefore, in cooperation with a control unit (described in detail later), a comfortable pedal speed and comfortable pedal resistance for the driver can be adjusted in any driving situation without being bound by predetermined gear steps.

[0015] According to a preferred embodiment of the present invention, at least one of the flexsplines is formed as a sleeve extending in the direction of the rotation axis. Preferably, both flexsplines are formed as sleeves extending in the direction of the rotation axis. Each sleeve is connected on one axial side to a rotary bearing, which rotatably supports the sleeve relative to, for example, a stationary or static housing. On the other axial side, each sleeve also has an engagement area for a wave generator, in particular external teeth for an internal gear. Viewed in the direction of the rotation axis, a sleeve internal space exists between the rotary bearing and the wave generator. That is, the sleeve internal space represents the volume enclosed by the flexspline, in particular the sleeve, in the radial direction, in particular as viewed from the rotation axis. Designing a flexspline with a sleeve as a flexspline pot benefits its bending and torsional properties and thus the reliable functioning of the wave gearing. However, in the present invention, the sleeve internal space is preferably utilized to significantly reduce installation space. It is therefore contemplated that at least one, and preferably both, electric motors are at least partially, preferably completely, arranged in the axial direction of the rotation shaft in the interior space of the sleeve of the strain wave gearing assigned to the respective electric motor. In other words, for example, it is contemplated that the drive electric motor is at least partially, preferably completely, arranged in the axial direction of the rotation shaft in the interior space of the sleeve of the drive strain wave gearing, and / or that the variable electric motor is at least partially, preferably completely, arranged in the axial direction of the rotation shaft in the interior space of the sleeve of the variable strain wave gearing. That is, each electric motor is preferably at least partially, preferably completely, surrounded in the radial direction by the respective sleeve of the flexspline. The respective statements regarding the electric motors particularly relate to the axial extension of the rotor and / or stator of the respective electric motor along the rotation shaft.Thus, according to a preferred embodiment, the drive electric motor and / or the variable electric motor are surrounded by a flexspline sleeve along the entire axial extension of their rotors and / or stators in the radial direction of the rotation axis. In this way, the sleeve interior space is used in the design to accommodate at least one electric motor, preferably both electric motors, thereby saving installation space. This is particularly effective when the external teeth of the two flexspline sleeves are arranged facing each other in the axial direction of the rotation axis.

[0016] Another preferred embodiment of the present invention also relates to the most space-saving possible arrangement of the electric motor. For this purpose, the wave generator, flexspline, and internal gear of the drive strain wave gearing and / or the variable strain wave gearing are preferably arranged so as to overlap each other in a gearing plane that lies perpendicular to the rotation axis. That is, the wave generator, flexspline, and internal gear of each strain wave gearing are arranged successively in this order in the radial direction of the rotation axis, particularly from the inside to the outside, and particularly aligned in this order. Furthermore, the flexspline, particularly the sleeve of the flexspline, is rotatably supported against a counterbearing in a bearing plane that lies perpendicular to the rotation axis. In the context of the present application, a counterbearing refers, for example, to a stationary or static part of the drive unit, for example, formed rigidly together with the housing or housing element. In this case, the drive electric motor and / or the variable strain wave motor are preferably arranged at least partially, preferably completely, between the gearing plane and the bearing plane. This again particularly relates to the axial extension of the rotor and / or stator of the respective electric motor along the rotation axis.

[0017] To enable particularly precise control of the electric motor of the drive unit according to the invention, in particular by a control unit described in more detail below, the drive electric motor and / or the variable speed electric motor are provided with at least one, in particular contactless, speed and / or angle of rotation sensor, in particular a Hall sensor. To accommodate the corresponding sensors in the drive unit as space-savingly as possible, it is furthermore conceivable, additionally or alternatively, for at least one, in particular contactless, speed and / or angle of rotation sensor to be arranged, in particular in the interior space of the sleeve of the flexspline. Each sensor is also preferably surrounded by the sleeve of the flexspline in the radial direction of the rotation axis. Furthermore, each sensor is preferably also located between the gear plane and the bearing plane.

[0018] Because many components of the drive unit are rotatable relative to one another and relative to the fixed housing, a large number of rolling bearings, e.g., (deep groove) ball bearings, are required to rotatably arrange these components, particularly around a rotation axis. In this case, it is preferable that all of these rotatable elements are rotatable about a common axis of rotation, particularly the bottom bracket axis or the axis of rotation of the running gear. The challenge in implementing this specifically in design is that these rolling bearings naturally have a minimum width to be able to perform their respective functions, but this minimum width, especially axially accumulated across the many rolling bearings, contributes significantly to the overall width of the drive unit. Therefore, the present invention also aims to save axial installation space for the rolling bearings by skillfully arranging them. For example, it is preferable that the rolling bearing for the output driven shaft and the rolling bearing for the input drive shaft are arranged in a common shaft bearing plane that is perpendicular to the axis of rotation. Therefore, these two rolling bearings are arranged radially relative to the axis of rotation, and therefore preferably overlap each other. It is particularly preferred that the two rolling bearings are formed as ball bearings with the same axial extension along the rotation axis and completely overlap in the radial direction of the rotation axis. That is, the two rolling bearings are not arranged side by side in the axial direction, but rather side by side in the radial direction, thereby reducing the width of one of the rolling bearings along the rotation axis. This arrangement of the rolling bearings for the output driven shaft and the input drive shaft essentially serves to save axial installation space in any drive device, regardless of, for example, the type of gearing and the motor configuration used. This is particularly relevant for use in bicycles assisted by electric motors, such as e-bikes or pedelecs. This aspect therefore represents an independent and separate invention that could be claimed separately, independent of the structural and functional features of the embodiments described herein, in addition to the development of the concept specifically described in this application.

[0019] In order to limit the axial width or extent of a drive unit, it is known to arrange, for example, multiple gears or multiple motors side by side, not axially but radially relative to the rotation axis. In other words, to limit the extent of the drive unit transverse to the direction of travel of the means of travel, an extension in the direction of travel or perpendicular to the direction of travel has been accepted. However, the object of the present invention is to avoid such an extension of the drive unit in the direction of travel and / or perpendicular to the direction of travel. Therefore, it is preferably intended that two electric motors and / or two strain wave gears are arranged coaxially with each other around the rotation axis. That is, the two electric motors and / or two strain wave gears have, in particular, the same rotation axis. Such an arrangement is not only particularly compact, but also has advantages with regard to the power flow through the drive train.

[0020] Having two wave gearings with at least a functionally or even structurally common internal gear is particularly space-saving when the two wave gearings are arranged close to each other. Therefore, it is preferable to form two wave gears adjacent to each other in the axial direction of the rotation axis. In this case, the electric motor is preferably directly connected axially further outward. In this case, the rotational bearing of the flexspline continues axially further outward with a fixed counterbearing, which may also include a freewheel. Therefore, it is generally intended that the wave gearing and the electric motor, and in particular the rotational bearing of the flexspline relative to the fixed counterbearing, and in particular also the freewheel between the flexspline and the fixed housing member, are preferably formed and arranged symmetrically with respect to a plane of symmetry extending perpendicular to the rotation axis. Therefore, the above-mentioned components are preferably arranged mirror-symmetrically with respect to the plane of symmetry along the rotation axis. This further has the advantage that highly redundant or identically structured components can be used for the variable wave gearing and the drive wave gearing, which advantageously allows the component multiplication of the drive unit to be kept relatively low.

[0021] As already explained, according to the present invention, the internal gear of the wave gearing is used as the gearing output or driven part. Therefore, drive energy derived from human muscle power can be introduced into the variable wave gearing via either a wave generator or a flexspline. Preferably, the input drive shaft is non-rotatably connected to the flexspline of the variable wave gearing in at least one rotational direction, and energy derived from human muscle power is introduced into the variable wave gearing via the flexspline. For this purpose, the input drive shaft is preferably connected to the flexspline of the variable wave gearing via a freewheel, which forms a non-moving or non-rotatable connection, particularly in the forward rotational or forward travel direction of the input drive shaft, thereby transmitting the corresponding rotational motion to the internal gear via the freewheel and the flexspline. The freewheel further allows, for example, free backward movement or allows the output driven shaft to be rotated faster by two electric motors than the input drive shaft rotated by the driver.

[0022] Preferably, a separate freewheel is arranged on the flexspline of the drive strain wave gearing. In particular, the flexspline of the drive strain wave gearing is supported on the fixed housing member via the freewheel. In this case, the freewheel rotates freely, particularly when the flexspline rotates in the forward traveling direction, and blocks, particularly when the flexspline rotates against the forward traveling direction. When the moving means travels forward, the output driven shaft and the common internal gear rotate forward. This causes the flexspline of the drive strain wave gearing to rotate forward as well. Because the freewheel rotates freely in this direction of rotation, the rotor of the drive electric motor does not need to be moved along with it. Therefore, when traveling without assistance from the electric motor, for example, using only human muscle power, this can be done with low pedal resistance. In contrast, when the drive electric motor operates to transmit auxiliary torque to the internal gear and thus to the output driven shaft, the flexspline is supported on the fixed housing via the freewheel, so that drive energy is transmitted from the drive electric motor via the wave generator and flexspline to the internal gear and thus to the output driven shaft.

[0023] As already explained, the freewheel is preferably arranged on the flexspline of the drive strain wave gearing so that it freewheels when the means of transport travels forward and the drive electric motor applies no or only very little drive energy. In these situations, it may be desirable to operate the drive electric motor as a generator for recovering kinetic energy. To achieve this, it is preferably provided that the freewheel is switchable between a switching position in which it freewheels in one direction of rotation and a switching position in which it engages or does not freewheel in this direction of rotation. In other words, in this direction of rotation, the freewheel functions as a switchable clutch. Alternatively, a separate clutch unit can be provided that can form a non-rotatable connection between the freewheel and the fixed housing member, thereby bypassing the freewheel and achieving the same result. In this way, the drive electric motor can be operated as a generator that receives drive energy from the internal gear and converts it into electrical energy. When the freewheel is switched to its non-freewheeling position, this means that it forms a non-rotatable connection between the flexspline and the fixed housing member, even in the forward direction of rotation. This blocks the flexspline and prevents it from rotating. In this way, drive energy is transmitted from the internal gear to the wave generator and thus to the electric drive motor, which then functions as a generator and converts this drive energy into electrical energy, for example, for charging an electrical energy storage device. In this way, the means of transport can thus be braked, in particular by recovering electrical energy. This use of a switchable freewheel and / or a separate clutch unit to operate the electric drive motor as a generator can basically be realized in any drive device with an electric motor, regardless of, for example, the type of transmission used and the configuration of the motor or motors.This aspect therefore represents an independent and distinct invention that can be claimed separately, independent of the structural and functional features of the embodiments described herein, in addition to the development of the concepts specifically described in this application.

[0024] A particular application of the switchable freewheel on the spline of the drive strain wave gear is, for example, a pedelec. According to legal regulations, assistance from the electric motor is permitted on a pedelec only up to a maximum speed of, for example, 25 km / h (45 km / h for an S-pedelec). From this maximum speed onward, the power generated by the electric motor in the drive unit must be equal to zero. Nevertheless, it is preferable for the driver to be able to travel faster beyond this speed limit using human muscle power. For this purpose, the transmission of high-speed rotation of the input drive shaft to the output driven shaft is desirable. In the drive unit according to the present invention, this means that the variable electric motor, i.e., the electric motor of the variable strain wave gear, responsible for adjusting the transmission ratio (transmission ratio) from the input gear shaft to the output gear shaft, must also transmit drive energy via the variable strain wave gear to the internal gear and thus to the output driven shaft. In this case, to avoid violating legal regulations, it is preferable to operate the drive electric motor as a generator above the legally prescribed maximum speed. In this case, the drive electric motor, in particular, operates as a generator, precisely by tapping off drive energy or power from the internal gear and converting it into electrical energy equivalent to the drive energy or power applied by the variable speed electric motor to the internal gear. Alternatively, the corresponding "negative" drive power of the drive electric motor can also be achieved by operating the drive electric motor in the opposite rotational direction to the variable speed electric motor, e.g., in the case of a variable speed electric motor with a corresponding rotational speed and / or torque. In this operating state, the total drive energy or power of the two electric motors is essentially zero, so that the pedestrian is driven purely by human muscle power, thereby meeting legal requirements. Therefore, the drive electric motor, as a whole, preferably operates with a drive power that is opposite and quantitatively equivalent to that of the variable speed electric motor, from the maximum driving speed of the means of transport, so that the total drive power applied by the electric motor to the output driven shaft, whether as a motor or as a generator, is equal to zero. The corresponding control of the electric motor is performed via a control unit, as described in more detail below.Furthermore, a suitable sensor system is provided for acquiring relevant operational data for the control unit, such as the current driving speed of the vehicle driven via the drive unit, which in this case does not provide any additional drive energy or drive force acting in the forward direction of the vehicle, but merely ensures the desired transmission ratio (gear ratio) between the input drive shaft and the output driven shaft.

[0025] As already explained for the rolling bearings, the freewheels also have a minimum necessary axial extension along the rotation axis. Therefore, it is also advantageous to arrange the freewheels, each with at least one rolling bearing, so that they overlap radially with respect to the rotation axis, thereby reducing their overall joint axial extension. Therefore, it is preferably provided that the rolling bearing is arranged so that it overlaps the freewheel between the counter bearing and the flexspline of the drive wave gearing in a bearing plane that lies perpendicular to the rotation axis. Additionally or alternatively, it is provided that the rolling bearing is arranged so that it overlaps the freewheel between the counter bearing and the flexspline of the variable wave gearing in a bearing plane that lies perpendicular to the rotation axis. In particular, it is preferred that the rolling bearing and the freewheel overlap by at least half, preferably at least two-thirds, and particularly preferably completely, with respect to their respective axial extension along the rotation axis. The counter bearing is a fixed element, i.e., a non-rotating element, and is non-rotatably connected to, for example, another fixed housing element of the drive unit.

[0026] Further reduction in the axial width of the drive unit is preferably achieved by arranging the rotary bearing together with the strain wave gearing in a plane perpendicular to the rotation axis. That is, the rotary bearing overlaps with the strain wave gearing in the radial direction of the rotation axis. For example, this can be the rotary bearing of the rotor of the electric motor. Such a rotary bearing is necessary in any case and must therefore be arranged in a space-saving manner. Therefore, according to a preferred embodiment of the present invention, the wave generator, the flexspline, and the internal gear of the drive strain wave gearing and / or the variable strain wave gearing are arranged together with the rotary bearing for the rotor of the drive electric motor and / or the variable electric motor, in particular relative to the counterbearing, in a gearing plane perpendicular to the rotation axis. That is, in this embodiment, the rotary bearing of the rotor of the electric motor is pressed into the strain wave gearing, in particular nested with it. The corresponding rotary bearing has an axial extension that corresponds to the axial extension of other components of the strain wave gearing, such as, for example, the wave generator or the rotary bearing between the wave generator and the flexspline, in particular a ball bearing. The rotary bearing preferably completely overlaps these elements in radial view and in axial extension.

[0027] In order to reduce the axial extent of the drive unit along the rotation axis, several planes oriented perpendicular to the rotation axis have already been described, in which the various components of the drive unit are arranged radially one above the other. Another such plane is an electronics bearing plane, also oriented perpendicular to the rotation axis, in which rotary bearings, in particular ball bearings, and a control unit are arranged. The rotary bearing is arranged, for example, between the stationary housing and the crankshaft when the drive unit is arranged around the crankshaft, or between a stationary housing element, such as a shaft, and the rotating hub housing when the drive unit is arranged on a wheel hub. The electronic control unit will be mentioned in more detail below. With regard to the optimal arrangement of the components of the drive unit relative to one another, it is preferably envisaged that the shaft bearing plane, the bearing plane of the flexspline of the variable wave gearing, the gear plane of the variable wave gearing, the symmetry plane, the gear plane of the drive wave gearing, the bearing plane of the flexspline of the drive wave gearing, and in particular also the electronics bearing plane are arranged consecutively in the direction along the rotation axis. This results in a particularly space-saving arrangement of the respective components.

[0028] As already mentioned above, the drive unit can be arranged, for example, in the case of a bicycle, in the region of the pedals in the center of the frame and in one of the wheel hubs. In a preferred embodiment, the drive unit is configured as a central drive unit, in particular with a rotational axis arranged coaxially with the pedal axis. In this case, the drive unit is arranged, for example, between the pedals, in particular between the pedal cranks. In this configuration, the drive unit is penetrated by a rotating axis, in particular a crankshaft, and has a fixed housing. In a preferred alternative, the drive unit is configured as a hub drive unit, in particular with a rotational axis arranged coaxially with the wheel axis. That is, the drive unit is arranged in the wheel hub, for example, in the rear wheel. In this case, the drive unit has a rotating hub housing penetrated by a fixed shaft and transmitting rotational motion to the wheel via spokes. Particularly preferably, the drive unit is configured as a central drive unit, for example, because, due to its central location in the bicycle frame, a particularly good weight distribution is achieved by a low center of gravity and a central location along the longitudinal axis.

[0029] It is always advantageous to minimize the axial extension of the drive unit. This is, of course, particularly advantageous when the drive unit is configured as a central drive unit, i.e., in the region of the bottom bracket axle. As mentioned at the beginning, due to the average human anatomy, efforts are made to ensure that the crank arms of the vehicle's pedals ideally have a distance of 140 to 180 mm. This can be achieved with the measures described above. Depending on how consistently these measures are implemented, even narrower dimensions can be achieved. Therefore, the extension of the drive unit along the rotation axis is preferably a maximum of 150 mm, preferably a maximum of 135 mm, particularly preferably a maximum of 120 mm, and in particular, for example, a maximum of 100 mm. The pedal crank arms should also be spaced apart from one another, preferably a maximum of 200 mm, particularly preferably a maximum of 170 mm, and very particularly preferably a maximum of 140 mm. In this way, a comfortable and anatomically correct pedaling experience can be achieved, even when the drive unit is configured as a central drive unit.

[0030] In a preferred embodiment, a control unit is provided for controlling the drive electric motor and / or the variable speed electric motor. In particular, the electronic control unit controls the rotation speed and / or rotation direction and / or torque of the electric motors individually and independently of each other. The control unit also controls the adjustment of the continuously variable transmission provided by the drive unit so that a comfortable pedaling is always possible regardless of the current driving speed. For example, the control unit controls the electric motor via a stored rotating magnetic field, e.g., a three-phase rotating magnetic field. Both the rotation speed behavior and the torque behavior of the motor are stored in such a rotating magnetic field. Since the corresponding control of the electric motor is part of the prior art and known to those skilled in the art, it will not be described in further detail here. The control unit can have a number of different features and functions, as explained below.

[0031] From a purely structural perspective, the control unit is integrated into the drive unit and is arranged in the already-mentioned electronics bearing plane, which is oriented perpendicular to the rotation axis, together with the rotation bearing for the crankshaft, for example. The control unit is therefore not simply attached to the outside of the drive unit, but is nested with the gearing components of the drive unit, which contributes to efficient use of installation space.

[0032] To control the drive unit's functions, various quantities must be determined that reflect the current operating state and that the control unit takes into account when controlling the electric motor. For example, the control unit is connected to a rotation angle sensor and / or a rotation speed sensor and / or a torque sensor on the input drive shaft. During operation, the input drive shaft is driven by the driver, for example, by pressing on the pedals. The control unit can use the corresponding quantities to determine the driver's intention to press harder, for example, when accelerating. Furthermore, the control unit is preferably connected to a road speed sensor, particularly located on the rear wheel hub, the rear wheel or its spokes, or the brake disc, that determines the overall road speed of the vehicle. A preferred embodiment contemplates that the road speed sensor is integrated into the drive unit and arranged together with it on the vehicle. In this case, the drive speed is determined, for example, on the output driven shaft. This is particularly possible when the driven wheels of the vehicle, for example the rear wheels, do not have their own freewheels and the traction means gear or chain wheel of the drive unit always rotates at the rotation speed of the wheels driven by the traction means. The control unit can, for example, check via a road speed sensor whether the road speed is above or below a maximum speed. If the maximum speed is exceeded, the control unit, as described above, for example, does not allow the transmission of auxiliary power from the electric motor to the output driven shaft. In that case, the control unit takes over control of the corresponding electric motor as already described. Furthermore, the control unit is preferably connected to rotational speed and / or rotational angle sensors, in particular Hall sensors, of the drive electric motor and / or the variable electric motor. Preferably, the control unit is also connected to current intensity sensors for the drive electric motor and / or the variable electric motor. From the current intensity, the control unit can estimate the respective torque of the electric motor. From this, the control unit can calculate the power of the electric motor together with the rotational speed and adjust it accordingly.

[0033] The main function of the control unit is preferably to control the rotation speed and torque of the drive motor and the variable speed electric motor so that the total drive energy or drive force, including the energy or power derived from human muscle power at the output driven shaft, corresponds to the energy or power demand of the drive unit. The corresponding energy or power demand is determined by the control unit based on measurement signals available to the control unit, taking into account, for example, the driver's pedal behavior, and from this, for example, an acceleration demand can be derived. The degree of driver assistance by the electric motor can be set in the control unit and taken into account by the control unit. Preferably, the control unit controls, for example, the rotation speed of the drive electric motor proportionally to the driving speed. In this way, the drive electric motor always receives the same amount of required drive energy or drive force at all driving speeds. Furthermore, preferably, the control unit is designed to activate a drive assistance function or a braking function depending on the rotation direction of a shaft driven by human muscle power, such as a crankshaft or an input drive shaft. In this way, the drive unit realizes coaster braking, for example, by deriving a brake command from the driver pedaling backwards. In this situation, the control unit may, for example, activate the switchable freewheel already mentioned above and operate the drive electric motor as a generator for converting kinetic energy into electrical energy, whereby the means of transport is braked.

[0034] Pedalecs with rear wheel suspension suffer from an effect known as pedal recoil or pedal kickback. This refers to the automatic rotation of the traction means gear, e.g., the chainring, whenever the suspension bounces. This causes the crankshaft and crank arms to rotate along with the pedals, which can be uncomfortable for the rider. In this case, the control unit is preferably configured to partially, and in particular completely, compensate for pedal kickback caused by the bouncing of the vehicle by controlling the variable electric motor. For this purpose, the control unit is connected to a spring displacement sensor of the vehicle, which determines, in particular, the bouncing itself and its extent and transmits this information to the control unit. By controlling the variable electric motor, the control unit also causes rotation of the crankshaft, and thus the pedals. In this case, the control unit is configured to control the variable electric motor based on the determined spring displacement to counteract the movement of the crankshaft due to pedal kickback. As a result, the pedals do not rotate despite the bouncing of the rear wheel. This compensation of pedal kickback can be realized in principle with any drive that can influence the pedal position. This aspect therefore represents a development of the concepts specifically described in this application as well as an independent and separate invention that can be claimed separately, independent of the structural and functional features of the embodiments described herein.

[0035] The control unit can also be connected to a display unit to inform the driver. The display unit can also be connected to the control unit, for example, via a cable, and can be located anywhere on the vehicle, such as on the handlebars. However, the display unit is preferably also located within the drive unit housing, specifically so that the control unit can be viewed from the outside through the drive unit's viewing window. Therefore, the control unit, together with the viewing window, is preferably located on the side of the drive unit facing away from the road, i.e., on the top surface of the drive unit. The viewing window is made of a transparent material, such as glass or plastic. The display unit preferably includes at least one display of information regarding the operating state of the vehicle, such as the current driving speed or the battery charge state. The display is preferably luminous and includes, for example, an LED. During operation of the vehicle, the driver can, for example, look down at the drive unit and read the corresponding information on the display unit. A display unit combined with a viewing window can essentially be implemented in any drive unit having electronics. This aspect therefore represents an independent and distinct invention that can be claimed separately, independent of the structural and functional features of the embodiments described herein, in addition to the development of the concepts specifically described in this application.

[0036] As already explained, the control unit can control the rotational position of the crankshaft, and therefore the pedals, by controlling the variable electric motor. For example, when cycling, it is typical that at least one of the pedals must be brought to a forward and upward position each time the bicycle is stopped. When the crankshaft is viewed from the side, with the forward direction of travel corresponding to clockwise rotation of the crankshaft and pedals, one of the pedals must be in a position, for example, at 2:00 p.m. With the pedals in this starting position, the rider can begin riding comfortably and accelerate quickly. This positioning, which traditionally must be adjusted by the rider by rotating the pedals in the opposite direction, can also be adjusted by the control unit. Therefore, preferably, the control unit is designed to bring the input drive shaft to the starting position by controlling the variable electric motor. This function is performed, for example, whenever the control unit detects a stop of the vehicle. In this way, the vehicle can be automatically started at any time without the rider having to pay attention to it. Positioning the pedals to the starting position can essentially be achieved with any drive device capable of influencing the pedal position. This aspect therefore represents an independent and distinct invention that can be claimed separately, independent of the structural and functional features of the embodiments described herein, in addition to the development of the concepts specifically described in this application.

[0037] The present invention will be explained in more detail below with reference to the embodiments shown in the drawings. [Brief explanation of the drawings]

[0038] [Figure 1] FIG. 2 is a schematic side view of a moving means with a central drive unit. [Figure 2] FIG. 2 is a schematic side view of a moving means including a hub drive unit. [Figure 3] FIG. 2 is a schematic external view of the central drive unit, in particular a plan view. [Figure 4] FIG. 2 is a schematic external view, particularly a plan view, of the hub drive unit. [Figure 5] FIG. 2 is a schematic cross-sectional view of a strain wave gear device. [Figure 6] FIG. 2 is a schematic cross-sectional view along a rotation axis passing through the central drive unit. [Figure 7] FIG. 2 is a cross-sectional view taken along a rotation axis passing through the hub drive unit. DETAILED DESCRIPTION OF THE INVENTION

[0039] Components that are the same or have the same function are provided with the same reference symbols, and repeated components are not referred to separately from one figure to another.

[0040] 1 and 2 each show a means of transport F, specifically a bicycle, in particular a pedelec. It can be driven simultaneously by an electric motor and human muscle power, particularly in such a way that the human muscle power is assisted by the electric motor. The means of transport F, as is known, comprises a frame 73 and two running gears 72, specifically a front wheel and a rear wheel. A pedal axle 65 is located at the center and lower end of the frame 73. A wheel axle 66 is located at the connection point between the frame 73 and the rear wheel. An embodiment in which a drive unit 1 is configured as a central drive unit and is located at the pedal axle 65 is shown in FIG. 1. Human muscle power is directly transferred to the drive unit 1 via a crankshaft. The gear output of the drive unit 1 is configured as a traction gear 10 (see FIGS. 3 and 6) and is connected to the rear wheel hub 2 via a traction means 3, e.g., a chain. In the embodiment according to FIG. 2, the drive unit 1 is designed as a hub drive unit and is arranged on the wheel axle 66. In this case, the gear output of the drive unit 1 is formed as a hub housing, and its rotational motion is transmitted to the rear wheel via spokes 59 (see Figures 4 and 7). The drive unit 1 is connected to the bottom bracket 4 via traction means 3, and human muscle power is introduced into the drive unit 1 via this traction means.

[0041] FIGS. 3 and 4 show plan views of the drive unit 1, respectively, as seen from the outside. FIG. 3 shows the drive unit 1 as a central drive unit. The drive unit 1's rotation axis 9 is located on the pedal axle 65, around which the crank arms 5 and pedals 6 of the mobility device F rotate during pedaling by the operator. A traction device gear 10 is used to transmit the rotational motion to the rear wheel hub 2. The width of the drive unit 1 is indicated by B1. The distance between the crank arms 5 is indicated by B2. To enable a comfortable pedaling motion that is compatible with the human anatomy, the distance B2 between the crank arms 5 should be between 140 mm and 180 mm. Therefore, the width B1 of the drive unit 1 must be correspondingly small. Furthermore, FIG. 3 shows a control unit 42 integrated into the drive unit 1. As will be explained in more detail below, the control unit 42 is connected to a number of sensors to detect the operating status of the drive unit 1 and the mobility device F. Furthermore, the control unit 42 is connected to a display unit 70, e.g., a light-emitting display, that can be viewed from the outside of the drive unit 1. For example, the display unit 70 is located behind a viewing window in the outer housing of the drive unit 1. An operator seated in the vehicle F can therefore view the display unit 70 by looking down. In FIG. 4, an embodiment of the drive unit 1 as a hub drive unit is shown. The rotation axis 9 of the drive unit 1 is therefore on the wheel axle 66, about which the rear wheel rotates when the vehicle F is moving. The rotation originating from the pedals 6 is transmitted to the drive unit 1 via the traction means gear 10. The drive unit 1 as a central drive unit is threaded by the rotating crankshaft 32 (see FIG. 6), while the drive unit as a hub drive unit is threaded by the stationary axle 11 about which the rear wheel rotates. The part of the hub housing that rotates about the axle 11 and is non-rotatably connected to the spoke 59 serves as the gearing output and thus the output driven shaft 12. The spoke 59 also transmits the rotational motion to the remainder of the rear wheel.

[0042] 5 shows a cross-sectional view of the wave gearing 13, 18 used in the present invention. The wave gearing 13, 18 is arranged around the rotation axis 9 and includes wave generators 16, 20, rotary bearings 17, 21, in particular (deep groove) ball bearings, flexsplines 15, 19, and internal gears 14, 14'. The internal gears 14, 14' and the wave generators 16, 20 are formed as rigid components, whereas the flexsplines 15, 19 are flexible or elastic. The wave generators 16, 20 are formed elliptical, and the flexsplines 15, 19 are attached to the wave generators 16, 20 via the rotary bearings 17, 21 so that the flexsplines 15, 19 fit the elliptical shape of the wave generators 16, 20 due to their elasticity. The internal gear 14, 14' has internal teeth and the flexspline 15, 19 has complementary external teeth, with the flexspline 15, 19 typically having fewer teeth than the internal gear 14, 14'. The elliptical shape of the wave generators 16, 20 causes the external teeth of the flexspline 15, 19 to be forced into the internal teeth of the internal gear 14, 14' along the major axis of the wave generator 16, 20. Elastic deformation of the flexspline 15, 19 simultaneously causes its external teeth to disengage from the internal teeth of the internal gear 14, 14' along the minor axis of the wave generator 16, 20. When the wave generators 16, 20 then rotate, the flexsplines 15, 19 rotate in the opposite direction with a reduction ratio of i=zH / (zH-zF), where zH is the number of teeth on the internal gears 14, 14' and zF is the number of teeth on the flexsplines 15, 19. If the flexsplines 15, 19 are held rigid, the internal gears 14, 14' will rotate in the same direction as the wave generators 16, 20, but at a correspondingly reduced speed. Such strain wave gears 13, 18 are summed gears and are known in the prior art and therefore do not need to be described in detail here.

[0043] FIG. 6 shows a cross section of the drive unit 1, formed as a central drive unit, along the rotation axis 9 or pedal axis 65. The pedal axis 65 is defined by a crankshaft 32 that can be driven by the operator via the pedals 6 and that passes through the drive unit 1 along the rotation axis 9. The crankshaft 32 is non-rotatably connected to an input drive shaft 33, via which drive energy applied by the operator is introduced into the gearing of the drive unit 1. The gearing output is formed by an output driven shaft 12 that is non-rotatably connected to a traction means gear 10, here a chain ring. The drive unit 1 has three sources of drive energy or power: human muscle power via the input drive shaft 33, and two electric motors 22, 27, specifically the variable speed electric motor 22 and the drive electric motor 27. The two electric motors 22, 27 are coupled to the drive train of the drive unit 1 via harmonic gearings 13, 18, respectively. Specifically, the variable electric motor 22 is coupled to the drive train via the variable strain wave gearing 13 , and the drive electric motor 27 is coupled to the drive train via the drive strain wave gearing 18 .

[0044] When the operator rotates the crankshaft 32 by depressing the pedal 6, the operator thereby rotates the input drive shaft 33. The input drive shaft 33 is connected to the flexspline 15 of the variable strain wave gearing 13 via a freewheel 36. The freewheel 36 is configured to engage when the input drive shaft 33 rotates in the forward direction of travel, creating a non-rotatable connection between the input drive shaft 33 and the flexspline 15. In contrast, the freewheel 36 rotates freely when the input drive shaft 33 rotates in the backward direction. Due to the engagement of the flexspline 15 with the internal gear 14' of the variable strain wave gearing 13, the internal gear 14' rotates together with the flexspline 15, strictly at a 1:1 transmission ratio. The internal gear 14' is also non-rotatably connected to the output driven shaft 12, so that, as a whole, the drive energy introduced by the operator by depressing the pedal 6 is transmitted to the output driven shaft 12 and thus to the traction means gear 10.

[0045] The variable electric motor 22 includes a stator 23 with stator windings 24. The stator 23 is arranged, for example, in a fixed counter-bearing 43 arranged tubularly around the crankshaft 32. Furthermore, the variable electric motor 22 has a rotor 26 with permanent magnets 25. The rotor 26 of the variable electric motor 22 is non-rotatably connected, in particular integrally, to the wave generator 16 of the variable wave gearing 13. The variable electric motor 22 therefore drives the wave generator 16 of the variable wave gearing 13. Depending on the direction of rotation of the variable electric motor 22, the rotational speed of the internal gear 14' is converted in various ways in relation to the rotational speed of the input drive shaft 33. In this way, the transmission ratio (transmission ratio) between the input drive shaft 33 and the output driven shaft 12 can be continuously adjusted. When the variable electric motor 22 rotates in the same direction as the input drive shaft 33, a speed-up ratio exists between the input drive shaft 33 and the output driven shaft 12, meaning that the output driven shaft 12 rotates faster than the input drive shaft 33. Correspondingly, when the variable electric motor 22 rotates in the opposite direction to the input drive shaft 33, a speed-down ratio exists between the input drive shaft 33 and the output driven shaft 12. In this case, the output driven shaft 12 rotates slower than the input drive shaft 33. Thus, collectively, the variable electric motor 22 on the wave generator 16 and the input drive shaft 33 on the flexspline 15 form the gearing inputs on the variable strain wave gearing 13. The internal gear 14' and the output driven shaft 12 form the gearing output. The variable electric motor 22 and variable strain wave gearing 13 form a continuously variable transmission between the input drive shaft 33 and the output driven shaft 12. The internal gear 14' forms the summing point between the two gearing inputs.

[0046] The drive electric motor 27 similarly comprises a stator 28 with a stator winding 29 and a rotor 31 with permanent magnets 30. The stator 28 is arranged in a fixed counter bearing 43, similar to the variable speed electric motor 22. The rotor 31 of the drive electric motor 27 is non-rotatably connected, particularly integrally, to the wave generator 20 of the drive wave gearing 18. The drive electric motor 27 therefore drives the wave generator 20 of the drive wave gearing 18. The drive energy of the drive electric motor 27 is transmitted to the flexspline 19 by rotation of the wave generator 20. The flexspline 19 is supported by the fixed housing member 56 via a freewheel 37. The drive energy is transmitted to the internal gear 14 of the drive wave gearing 18 via the flexspline 19. The internal gear 14 of the drive strain wave gearing 18 is non-rotatably connected to the internal gear 14' of the variable strain wave gearing 13, and in particular is formed integrally therewith as a common internal gear 14, 14' of the two strain wave gearings 13, 18. In this non-rotatably connected or integrally formed common internal gear 14, 14', the drive energy or drive force of the two electric motors 22, 27 and human muscle power introduced via the crankshaft 32 are summed and transmitted to the output driven shaft 12. The drive electric motor 27 is configured to supply the majority of the electrical drive energy or drive force for the traveling operation of the means of transportation F. In order to drive the internal gear 14 in the forward traveling direction, the wave generator 20 must also rotate in the forward traveling direction. This reverses the rotation direction of the flexspline 19, i.e., in the backward direction. Therefore, in order to transmit the drive energy from the wave generator 20 to the internal gear 14, the flexspline 19 must be supported in the backward direction by a fixed housing member. The freewheel 37 is therefore configured to create a non-rotatable connection between the flexspline 19 and the fixed housing member 56 when the flexspline 19 is in a backward rotational direction. This prevents the flexspline 19 from rotating backwards, thereby transferring all of the drive energy applied to the wave generator 20 from the drive electric motor 27 to the internal gear 14 and making it available for driving the moving means F.

[0047] On the other hand, if the drive electric motor 27 is not activated or is rotated more slowly than the internal gear 14, for example by the operator using human muscle power, the output driven shaft 12 rotates the internal gear 14, and due to its engagement with the flexspline 19, the flexspline 19 as well, in the forward traveling direction. However, the freewheel 37 allows free rotation of the flexspline 19 in the rotation direction corresponding to the forward traveling direction, so that, due to cooperation of the rotary bearing 21 between the flexspline 19 and the wave generator 20, no driving energy is transmitted to the wave generator 20 and therefore to the rotor 31 of the drive electric motor 27. Therefore, when the driver presses the pedal using only muscle power, it is not necessary to move the drive electric motor 27, which makes it possible to press the pedal 6 easily and comfortably.

[0048] According to a preferred embodiment of the invention, the freewheel 37 is configured as a switchable freewheel 37. This means that the control unit 42 can control the freewheel to create a non-rotatable connection between the flexspline 19 and the fixed housing member 56 in both directions of rotation. This allows drive energy to be transmitted from the internal gear 14 to the wave generator 20 and thus to the rotor 31 of the electric drive motor 27, even when the flexspline 19 is blocked in the forward direction of rotation. It is therefore possible to operate the electric drive motor 27 as a generator and convert the rotational energy from the internal gear 14 into electrical energy, which can be supplied, for example, to a battery. Operating the electric drive motor 27 as a generator brakes the means of movement F, which can also be used as a brake. Furthermore, as already mentioned above, the electric drive motor 27 can be operated as a generator or in motor mode in order to negatively compensate for the drive energy or force introduced into the drive train by the variable speed electric motor 22. This is useful, for example, to comply with legal regulations that, from a certain maximum speed, it is not permitted to transmit any more drive power by the electric motors 20, 27 to the output driven shaft 12. By means of the switchable freewheel 37 and the use of the drive electric motor 27 to negatively compensate for the power introduced by the variable electric motor 22, it is possible to drive the variable electric motor 22 to still provide a continuously variable transmission even at driving speeds higher than the legal maximum speed. In this case, the required delivery of drive energy to the drive train is negatively compensated by the drive electric motor 27.

[0049] The present invention is characterized by a particularly narrow design along the rotation axis 9. To this end, the drive unit 1 includes a series of structural peculiarities, which are mentioned below. On the one hand, the present invention utilizes two harmonic gears 13, 18, which are non-rotatably connected to one another, or even formed integrally with one another, and which combine the drive energy or power of two electric motors 22, 27 with the drive energy or power from human muscle power in two internal gears 14, 14'. The design using a common internal gear 14, 14' allows the two harmonic gears 13, 18 to be arranged close to one another, thereby reducing the required installation space in the axial direction of the rotation axis 9.

[0050] Furthermore, the flexsplines 15, 19 of the two strain wave gearings 13, 18 are formed together with sleeves 63, 64. The sleeves 63, 64 are cylindrical extensions of the flexsplines 15, 19 in the axial direction of the rotation shaft 9 from the engagement region with the internal gears 14, 14'. In this case, the two strain wave gearings 13, 18 are located at the center of the drive unit 1 when viewed axially along the rotation shaft 9, while the sleeves 63, 64 extend in a direction away from the center of the strain wave gearings 13, 18 and the drive unit. The sleeves 63, 64 are supported on a fixed housing member, for example, the counter bearing 43, via respective rotary bearings 45, 48 at their axial ends opposite the engagement region with the internal gears 14, 14'. In other words, the flexsplines 15, 19 extend, as viewed in the axial direction of the rotary shaft 9, from gearing planes E1, E1' arranged perpendicular to the rotary shaft 9, where the components of the strain wave gearings 13, 18, the wave generators 16, 20, the rotary bearings 17, 21, the flexsplines 15, 19, and the internal gears 14, 14' overlap in the radial direction of the rotary shaft 9, to bearing planes E2, E2' where the flexsplines 15, 19 overlap with the rotary bearings 45, 48 in the radial direction of the rotary shaft 9. The flexsplines 15, 19 each have one sleeve interior space 69 within their hollow cylindrical bodies. In order to avoid leaving any unused space here, in the illustrated embodiment of the invention, the electric motors 22, 27 are arranged in their respective sleeve interior spaces 69, more precisely, the variable electric motor 22 in the sleeve interior space 69 of the flexspline 15 of the variable wave gearing 13, and the drive electric motor 27 in the sleeve interior space 69 of the flexspline 19 of the drive wave gearing 18. In particular, the two electric motors 22, 27 are arranged inside the flexsplines 15, 19, in particular in the corresponding sleeve interior spaces 69, over the entire axial extent of the stators 23, 28 with their stator windings 24, 29 and the rotors 26, 31 with their permanent magnets 25, 30. Furthermore, the electric motors 22, 27 are arranged between the gearing planes E1, E1' and the bearing planes E2, E2'. In particular, the variable speed electric motor 22 is arranged between the gearing plane E1' and the bearing plane E2', whereas the drive electric motor 27 is arranged between the gearing plane E1 and the bearing plane E2.

[0051] Another core idea of ​​the invention is to arrange some of the rolling bearings at the same height as other components in the axial direction of the rotary shaft 9, thereby making the drive unit 1 particularly narrow in the axial direction of the rotary shaft 9. The individual components of the drive unit 1 are therefore nested within one another as viewed in the axial direction of the rotary shaft 9, such as the electric motors 22, 27 and the strain wave gears 13, 18 by being arranged in the sleeve interior space 69. For example, it is envisaged that in the gear plane E1 the rolling bearing 46, e.g. a ball bearing, for the rotor 31 of the drive electric motor 27 against the fixed counter bearing 43 is arranged together with the drive strain wave gear 18. The rolling bearing 46 overlaps, for example, with the other components of the drive strain wave gear 18, such as the wave generator 20, the rolling bearing 21, the flexspline 19 and the internal gear 14, over its entire axial extent in the direction of the rotary shaft 9. In this way, the rolling bearing 46 does not need to be formed axially in series with these components of the drive strain wave gear 18, which reduces the overall extent of the drive unit 1. The same applies to the rotary bearing 47 for the rotor 26 of the variable speed electric motor 22. This rotary bearing 47 is configured identically to the rotary bearing 46 and is likewise arranged in the gear plane E1′ of the variable wave gearing 13.

[0052] Another implementation of this basic idea is found in the bearing planes E2, E2'. Viewed in the radial direction of the rotary shaft 9, in the bearing plane E2 of the flexspline 19, the rotary bearing 45 that supports the flexspline 19 in the fixed counter bearing 43 and the freewheel 37 between the flexspline 19 and the fixed housing member 56 overlap. Similarly, in the bearing plane E2' of the flexspline 15, viewed in the radial direction of the rotary shaft 9, the rotary bearing 48 that mounts the flexspline 15 in the fixed counter bearing 43 and the freewheel 36 between the flexspline 15 and the input drive shaft 33 overlap. This also reduces the overall axial extent of the drive unit 1.

[0053] Rotation bearings 49 and 50, both preferably ball bearings, are also arranged in a common shaft bearing plane E3 that is perpendicular to rotation axis 9. Rotation bearing 49 is arranged between input drive shaft 33 and output driven shaft 12 and supports them so that they can rotate relative to each other. Rotation bearing 50 is arranged between output driven shaft 12 and fixed housing member 57. Rotation bearings 49, 50 are formed to the same structure (except for the necessary diameter difference) and are arranged concentrically around rotation axis 9, and in particular completely overlap when viewed in the radial direction of rotation axis 9.

[0054] Another rotary bearing 44 between the crankshaft 32 and the fixed housing member 56 is located in another electronics bearing surface E4, which is arranged perpendicular to the rotation axis 9 and in which the rotary bearing 44 at least partially overlaps the control unit 42 in the direction of rotation of the rotation axis 9. Thus, the control unit 42 is not only located outside the drive unit 1, but is also nested with the gearing elements of the drive unit 1, thereby also reducing its axial extent. The control unit 42 is externally covered by a housing cover 55.

[0055] The wave gearings 13, 18, in particular the flexsplines 15, 19, as well as the electric motors 22, 27, the rotors 26, 31 for the counter-bearing 43 and the rotary bearings 46, 47 for the wave generators 16, 20, and the freewheels 36, 37, are designed and arranged symmetrically about a plane of symmetry E5, which in this case is arranged perpendicular to the axis of rotation 9 and between the wave gearings 13, 18.

[0056] The control unit 42 is configured to control the electric motors 22, 27. To be able to perform its respective control functions, the control unit 42 requires various measurements related to the current operating state of the drive unit 1 and the means of transportation F. For example, the control unit 42 is connected to a spring displacement sensor 67 and a road speed sensor 68, both of which are shown in FIGS. 1 and 2 and arranged on the rear wheels. Furthermore, the control unit 42 is connected to a current intensity sensor 71, by means of which the control unit 42 measures the intensity of the current flowing through the electric motors 22, 27, respectively. Furthermore, the control unit 42 is connected to a Hall sensor 38 on the drive electric motor 27 via a circuit board 39 and to a Hall sensor 40 on the variable speed electric motor 22 via a circuit board 41. Both the circuit boards 39, 41 and the Hall sensors 38, 40 are also arranged in the respective sleeve interior spaces 69 together with the respective electric motors 22, 27. The rotation speed and angular position of the electric motors 22, 27 can be determined via these sensors 38, 40. Further sensor units 51, 52 connected to the control unit 42 have a fixed housing, e.g., a stationary member 52 mounted on the counter bearing 43, and a member 51 that rotates with the input drive shaft 33. The sensor units 51, 52 determine the torque applied to the crankshaft 32 and thus the input drive shaft 33, e.g., by human muscle force, as well as the angular position. The rotational speed of the crankshaft 32 and thus the rotational speed of the input drive shaft 33 can likewise be determined from the time derivative of the angular position. The stationary member 52 of the sensor units 51, 52 is attached, particularly by means of a mounting nut 53, to the counter bearing 43, particularly in the region where the counter bearing 43 is supported opposite the crankshaft 32 via a rotating bearing 54, particularly a needle bearing.

[0057] FIG. 7 shows a cross section of a drive unit 1 configured as a hub drive unit along the rotation axis 9 or wheel axle 66. The configuration of the drive unit 1 is almost identical to that of a drive unit configured as a central drive unit. Therefore, only differences from the previous embodiment will be noted. In particular, when the drive unit 1 is configured as a hub drive unit, there is no crankshaft 32 penetrating the drive unit 1. Instead, the drive unit 1 is penetrated by a stationary shaft 11, which includes, for example, a counter bearing 43, several fixed housing members 56, 57, and a connector housing 58 for the electronic control unit 42. The input drive shaft 33 is not driven directly by the pedals 6 or the crankshaft 32; instead, pedal movement is transmitted to the input drive shaft 33 via the traction means 3 and the traction means gear 10. At the same time, the output driven shaft 12 is not connected to the traction means gear 10, but is formed by a rotating hub housing having hub housing members 60, 61 non-rotatably connected to the internal gears 14, 14′. The spokes 59 of the rear wheel are arranged in the hub housing members 60, 61. Furthermore, a brake disc 62 is also arranged on the hub housing. In other respects, the embodiment of the drive unit 1 as a hub drive unit corresponds to the embodiment as a central drive unit, so reference is made to the above description to avoid repetition.

[0058] Overall, the invention makes it possible to provide a drive unit 1 that is particularly compact in the sense that it extends axially along the rotation axis 9. Furthermore, the drive unit 1 according to the invention can be used to realize a large number of control functions that are desired for modern means of transport F, for example pedelecs.

Claims

1. A drive unit (1) for a means of transport (F) that can be driven simultaneously by human muscle power and by drive energy provided by an electric motor, comprising: an input drive shaft (33) for transmitting drive energy generated from human muscle force; an output driven shaft (12) for delivering drive energy to a running gear (72); a drive strain wave gearing (18) disposed around a rotation axis (9) and having a first wave generator (20), a first flexspline (19) and an internal gear (14); a drive electric motor (27) arranged around a rotation axis (9) having a stator (28) and a rotor (31), the drive electric motor (27) being capable of transmitting drive energy to the output driven shaft (12) via the drive strain wave gearing (18); a variable strain wave gearing (13) disposed in a drive train between an input drive shaft (33) and an output driven shaft (12), the variable strain wave gearing (13) having a second wave generator (16), a second flexspline (15) and an internal gear (14'), the variable strain wave gearing (13) being arranged to receive drive energy derived from human muscle power of the input drive shaft (33) and transmit it to the output driven shaft (12) of the drive unit (1); and a variable speed electric motor (22) having a stator (23) and a rotor (26), wherein drive energy of the variable speed electric motor is also introduced into the variable wave gearing (13), and the variable wave gearing (13) is capable of transmitting the total energy from the human muscle power and the variable speed electric motor (22) to the output driven shaft (12), wherein the internal gear (14) of the drive wave gearing (18) and the internal gear (14') of the variable wave gearing (13) are configured to be non-rotatable with respect to each other, and the drive unit transmits the total drive energy from the human muscle power, the drive electric motor (27), and the variable speed electric motor (22) to the output driven shaft (12).

2. 2. A drive unit (1) according to claim 1, characterized in that at least one of the variable strain wave gearing (13) and the variable electric motor (22) is arranged around the rotation axis (9).

3. 3. The drive unit (1) according to claim 1 or 2, characterized in that the variable wave gearing (13) forms a continuously variable transmission between the input drive shaft (33) and the output driven shaft (12).

4. at least one of the flexsplines (15, 19) is formed as a sleeve (63, 64) extending in the direction of the rotation axis (9), the sleeve is connected to a rotation bearing (45, 48) on one side in the axial direction and has an engagement area for the wave generator (16, 20) on the other side in the axial direction, and a sleeve internal space (69) exists between the rotation bearing (45, 48) and the wave generator (16, 20) as seen in the direction of the rotation axis (9); 4. A drive unit (1) according to claim 1, wherein at least one of the electric motors (22, 27) is at least partially arranged in the axial direction of the rotation shaft (9) in the sleeve interior space (69) of the strain wave gear device (13, 18) assigned to the respective electric motor (22, 27).

5. 5. The drive unit (1) according to claim 1, wherein the wave generator (16, 20), the flexspline (15, 19), and the internal gear (14, 14') of at least one of the drive wave gearing (18) and the variable wave gearing (13) are arranged to overlap in a gearing plane (El, El') that lies perpendicular to the rotation axis (9), the flexspline (15, 19) is rotatably supported relative to an opposing bearing (43) in a bearing plane (E2, E2') that lies perpendicular to the rotation axis (9), and at least one of the drive electric motor (27) and the variable electric motor (22) is arranged between the gearing plane (El, El') and the bearing plane (E2, E2').

6. 6. The drive unit (1) according to claim 1, wherein at least one of a rotation speed sensor and a rotation angle sensor (38, 40) is provided in at least one of the drive electric motor (27) and the variable speed electric motor (22), and the at least one of the rotation speed sensor and the rotation angle sensor (38, 40) is arranged in the sleeve inner space (69) of the flexspline (15, 19).

7. 7. A drive unit (1) according to any one of claims 1 to 6, characterized in that the rotary bearing (50) for the output driven shaft (12) and the rotary bearing (49) for the input drive shaft (33) are arranged in a common shaft bearing plane (E3) lying perpendicular to the rotation axis (9).

8. 8. The drive unit (1) according to any one of claims 1 to 7, characterized in that the two electric motors (22, 27) and at least one of the two strain wave gear devices (13, 18) are arranged coaxially with each other around the rotation axis (9).

9. 9. The drive unit (1) according to claim 1, wherein the strain wave gearing (13, 18) and the electric motor (22, 27) are formed and arranged symmetrically to one another with respect to a plane of symmetry (E5) extending perpendicular to the rotation axis (9).

10. 10. The drive unit (1) according to claim 1, wherein the input drive shaft (33) is connected to the flexspline (15) of the variable wave gearing (13) so as to be non-rotatable in at least one direction of rotation, and the energy derived from human muscle force is introduced into the variable wave gearing (13) via the flexspline (15).

11. 11. The drive unit (1) according to claim 1, wherein the flexspline (19) of the drive strain wave gear device (18) is supported on a fixed housing member (56) via a freewheel (37).

12. 12. The drive unit (1) according to claim 11, characterized in that the freewheel (37) is configured switchably or the flexspline (19) and the fixed housing member (56) can be non-rotatably connected by a separate clutch unit, whereby the drive electric motor (27) can operate as a generator that receives the drive energy from the internal gear (14) and converts it into electrical energy.

13. 13. The drive unit (1) according to any one of claims 1 to 12, characterized in that the drive electric motor (27) is operated with a driving force that is opposite and quantitatively equal to that of the variable speed electric motor (22) from the maximum travel speed of the means of transportation (F), so that the total driving force applied from the electric motors (22, 27) to the output driven shaft (12) is equal to zero.

14. a rotation bearing (45) is disposed between the counter bearing (43) and the flexspline (19) of the drive strain wave gear device (18) so as to overlap with the freewheel (37) in a bearing plane (E2) positioned perpendicular to the rotation axis (9); and wherein a rotation bearing (48) is arranged to overlap a freewheel (36) between an opposing bearing (43) and the flexspline (15) of the variable wave gear device (13) in a bearing plane (E2′) that is perpendicular to the rotation axis (9).

15. 15. The drive unit (1) according to claim 1, wherein the wave generator (16, 20), the flexspline (15, 19), and the internal gear (14, 14') of at least one of the drive wave gearing (18) and the variable wave gearing (13) are arranged together with a rotation bearing (46, 47) for the rotor (26, 31) of at least one of the drive electric motor (27) and the variable electric motor (22) in a gearing plane (El, El') lying perpendicular to the rotation axis (9).

16. 16. The drive unit (1) according to any one of claims 1 to 15, characterized in that the drive unit (1) is formed as a central drive unit or the drive unit (1) is formed as an auxiliary drive unit.

17. 17. Drive unit (1) according to any one of claims 1 to 16, characterized in that the extension (B1) of the drive unit (1) along the axis of rotation (9) is at most 150 mm.

18. A control unit (42) is provided for controlling at least one of the drive electric motor (27) and the variable speed electric motor (22), said control unit having at least the following characteristics: the control unit is arranged together with a rotation bearing (44) for the crankshaft (32) in an electronics bearing plane (E4) that is located perpendicular to the rotation axis (9); the control unit is connected to at least one of a rotation angle sensor and a rotation speed sensor on the input drive shaft (33) and a torque sensor (51, 52); The control unit is connected to a road speed sensor (68). the control unit is connected to at least one of a rotation speed sensor and a rotation angle sensor (38, 40) of the drive electric motor (27) and / or the variable speed electric motor (22); the control unit is connected to a current intensity sensor (71) for at least one of the drive electric motor (27) and the variable electric motor (22); the control unit controls the rotation speed and torque of the drive electric motor (27) and the variable speed electric motor (22) so that the total drive energy, including the energy derived from the human muscle force at the output driven shaft (12), corresponds to the energy demand of the drive unit (1); The control unit controls the rotation speed of the electric drive motor (27) in proportion to the running speed. The control unit (42) activates a driving assist function or a braking function depending on the rotation direction of the shafts (32, 33) driven by human muscle power. the control unit is connected to a spring displacement sensor (67) of the moving means (F) and at least partially compensates for pedal recoil caused by bounding of the moving means (F) by controlling the variable electric motor (22); The control unit is connected to a display unit (70) that can be seen from the outside through a viewing window in the drive unit (1). the control unit controls the variable speed electric motor (22) to move the input drive shaft (33) to a start position; 18. A drive unit (1) according to any one of claims 1 to 17, characterized in that it comprises at least one of the following:

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