Drive system and control method for a two-wheeled vehicle having slope-assist mode

Abstract

The proposed solution relates in particular to a drive system for a two-wheeled vehicle, in particular an electric bicycle (F), a motorised scooter, an e-scooter or an electric motorcycle, the drive system having: - a drive shaft (1); - an output element (2) for transmitting a drive force applied to the drive shaft (1) to a wheel (112) of the two-wheeled vehicle (F); - at least one motor (11, 12) for generating at least some of the drive force; and - control electronics (8) for controlling the at least one motor (11, 12). The control electronics (8) are configured to operate the at least one motor (11, 12) in a slope-assist mode in which a rotation of the output element (2) is counteracted via the at least one motor (11, 12).

Description

[0001] Drive system and control method for a two-wheeler with slope holding mode

[0002] Description

[0003] The proposed solution relates in particular to a drive system for a two-wheeled vehicle, in particular for an electric bicycle, an electric scooter, an e-scooter or an electric motorcycle.

[0004] It is known to provide a push assist function via an electric motor drive unit of an electric bicycle, i.e., a so-called e-bike or pedelec, to assist a user when pushing the electric bicycle or starting off, for example, on an incline. The push assist function is typically triggered by an operating signal, for example, by operating a control element on the handlebars of the electric bicycle. The maximum speed achievable with the push assist function is set by the drive unit's control electronics and is usually limited by law. A maximum speed of 3 to 6 km / h is typically achieved with a push assist function.

[0005] A corresponding push assist, or operation of at least one motor of the drive unit in a push assist mode, is typically also used when a user pushes the electric bicycle up a slope or stairs. In this context, it is typically provided that the user must keep at least one control element of the drive system actuated in order to maintain motor assistance for pushing the electric bicycle. If the corresponding control element is no longer actuated, the push assist mode is deactivated. However, this then regularly results in a user having to hold the comparatively heavy electric bicycle directly on a slope or stairs using muscle power alone, without motor assistance.

[0006] Against this background, the proposed solution is based on the object of providing a drive system improved in this respect with greater user comfort. This object is achieved in particular with a drive system according to claim 1.

[0007] Thus, a proposed drive system provides that control electronics of the drive system are configured to operate at least one motor, via which at least part of a drive force, e.g. in the form of an assist force, can be made available to an output element, in a slope holding mode in which a rotation of the output element is counteracted via the at least one motor.

[0008] In a drive mode of the drive system that is different from the slope hold mode, a drive force is transmitted to a wheel of the two-wheeler via the output element. By counteracting a rotation of the output element in a slope hold mode, it can be achieved in particular that a force acting on the output element on the output side does not lead to an undesired backward movement of the electric bicycle. Rather, the at least one motor is operated in the slope hold mode in such a way that a rotation of the output element is counteracted. In the slope hold mode, the rotation of the output element in a reverse direction can thus be counteracted, and the motor drive system can thus prevent the two-wheeler from rolling backward on a slope or down stairs as a result of the weight acting on the two-wheeler.

[0009] The control electronics can therefore be configured, in particular, to counteract, via the at least one motor, a rotation of the output element in a reverse direction of rotation in the slope-holding mode as a result of a force acting on the output element on the output side. The reverse direction of rotation runs opposite to a forward direction of rotation of the output element, in which the output element can be rotated with motor assistance in a drive mode for driving the two-wheeler.

[0010] In the slope-holding mode, for example, an assist force can be applied via the at least one motor to hold the output element in a rest position. In the slope-holding mode, the at least one motor of the drive system is consequently controlled by the control electronics to maintain a standstill of the output element, even if an external force acts on the output element, under the effect of which the output element is loaded into a reverse rotation.

[0011] For example, in this context, the control electronics are configured to regulate the output element to a speed of 0 revolutions per minute via the at least one motor in the slope hold mode. For corresponding speed control, the control electronics can be coupled to at least one sensor device of the drive system. Such a sensor device comprises, for example, a speed sensor for the sensory detection of a rotation of the output element. A corresponding sensor device can alternatively or additionally comprise a wheel sensor on the two-wheeler, e.g. an electric bicycle, via which a rotation of a wheel of the two-wheeler that can be driven with motor assistance by means of the at least one motor can be detected by sensor.

[0012] In an alternative embodiment, which is advantageous, for example, in an electric scooter, an e-scooter or an electric motorcycle, the control electronics can be configured to set the output element to a speed of 0 revolutions per minute via the at least one motor in the slope hold mode by a) closing low-side MOSFETs or high-side MOSFETS (“MOSFET”, short for “Metal Oxide Semiconductor Field-Effect Transistor”) of the control electronics for a defined period of time or b) actively clamping IGBTs (“IGBT” short for “Insulated-Gate Bipolar Transistor”) of the control electronics (English: “active clamping”).This includes, in particular, activating the low-side MOSFETs or the high-side MOSFETs of the control electronics to create an active short circuit, i.e., in particular, permanently switching on all low-side MOSFETs or all high-side MOSFETs to create an active short circuit and thus prevent the motor from rotating backwards. Low-side MOSFETs or high-side MOSFETs are provided in the control electronics, for example, for controlling at least one motor with pulse width modulation, in particular for controlling the two-wheeler in a drive mode different from the push-assist mode.

[0013] In one embodiment, the control electronics are configured to operate the at least one motor in a push-assist mode, in which, when the bicycle is pushed by a user, a drive torque can be transmitted from the at least one motor with an assist force to the output element (for driving the electric bicycle in a forward direction). The control electronics can then be further configured to operate the at least one motor in the slope-holding mode only after the user has activated the push-assist mode. Consequently, in such an embodiment, the slope-holding mode can only be specified by the control electronics if the push-assist mode has previously been activated. This prevents unwanted blocking of the output element due to inadvertent activation of the slope-holding mode, and limits automatic switching to the slope-holding mode to specific operating situations.

[0014] For example, it is provided that maintaining the push-assist mode and the resulting transmission of drive torque to the output element requires the user to continue to operate a control element. The control electronics can then be configured to deactivate the push-assist mode and operate the at least one motor in slope-holding mode in response to the cessation of operation of the control element. For example, maintaining the push-assist mode can require that a user on the two-wheeler actuates, in particular holds, a specific control element, such as a button on the handlebars. If the corresponding control element is no longer actuated, the push-assist mode is automatically deactivated.To prevent the bicycle from rolling backward on a slope or up stairs due to the force of gravity when the push-assist mode is deactivated (at least without a user holding the bicycle in position solely through muscle power), this embodiment allows at least one motor to be automatically operated in slope-holding mode when the push-assist mode has been deactivated. By operating the at least one motor in slope-holding mode, the bicycle can thus be held in position with motor support, even if the push-assist mode has been deactivated by a user, particularly accidentally, on a slope or up stairs.

[0015] In principle, the maintenance of slope hold mode can be time-limited. For example, the control electronics can be configured to operate at least one motor in slope hold mode for a specified period of time. Unless the user initiates an extension of slope hold mode, slope hold mode will be automatically deactivated after the specified period of time has elapsed.

[0016] In order to inform a user in this context that the slope holding mode is only maintained for a limited time, a possible further development can provide that the drive system comprises an output element via which information about the predetermined time period and / or its expiration can be output to a user of the two-wheeler visually and / or acoustically. For example, the drive system here comprises at least one output element with a display and / or a loudspeaker in order to inform a user on the two-wheeler that and for how long the slope holding mode is (still) active. If the slope holding mode is maintained for a limited time, it can also be provided that the control electronics are configured to operate the at least one motor in the slope holding mode only for the predetermined time period after a push assistance mode has been deactivated.If, for example, the walk assistance mode is ended because a user of the two-wheeler no longer operates a control element for the walk assistance mode, the at least one motor will only be operated in the slope holding mode for a predetermined time after the walk assistance mode has ended. For example, a timer is started for this purpose when the walk assistance mode ends, after which the slope holding mode is deactivated. In this way, operation automatically changes from the walk assistance mode to the slope holding mode, but the slope holding mode only remains activated for a predetermined time. For example, a predetermined time period for this can be in the range of 1 to 60 seconds, in particular in the range of 1 to 10 seconds or from 2 to 5 seconds and in particular 3 seconds.

[0017] The proposed solution also relates to a method for controlling a drive system of a two-wheeled vehicle. The drive system includes a drive shaft for driving the two-wheeled vehicle. A drive force applied to the drive shaft is transmitted to a wheel of the electric bicycle via an output element. At least one electronically controllable motor is provided for generating at least part of the drive force. In the proposed control method, the at least one motor is operable in a slope-holding mode, in which rotation of the output element is counteracted via the at least one motor.

[0018] In the slope hold mode, the two-wheeler can thus be prevented from rolling backward on a slope or on stairs by controlling the at least one motor to counteract a force acting on the output side of the output element and to hold the two-wheeler immobile, without a user having to (solely) apply counteracting muscle force to the two-wheeler, for example via the handlebars of the two-wheeler.

[0019] An embodiment of a proposed control method can be implemented in particular with an embodiment of a proposed drive system. The features and advantages explained above and below for embodiments of a proposed drive system therefore also apply to embodiments of a proposed control method, and vice versa. This also applies to a proposed computer program product containing instructions which, when executed by at least one processor of a control unit (implementing the control electronics) of a drive system of a two-wheeler comprising a drive unit, cause the at least one processor to execute an embodiment of a proposed control method.

[0020] In principle, the at least one motor of the drive system can be an electric motor or a hydraulic motor. Furthermore, the drive system can also comprise more than one electric motor, in particular two electric motors, which, in combination with a multi-stage transmission of the drive system, can enable a continuously variable transmission ratio.

[0021] If the drive system is intended for an electric bicycle, at least one motor can provide an assist force as a power-driven portion of the drive force. This motor-generated portion of the drive force can then be applied to the drive shaft in addition to a muscle-powered portion of the drive force, which is applied by a user of the electric bicycle to a pedal crank connected to the drive shaft. In the case of an electric scooter, an e-scooter, or an electric motorcycle, the drive force can, in turn, be applied entirely by the motor.

[0022] The attached figures illustrate possible embodiments of the proposed solution.

[0023] Here we show:

[0024] Figure 1 schematically shows an electric bicycle with an embodiment variant of a proposed drive system, wherein the electric bicycle is positioned on a slope and is held in a current slope position with motor support via a slope holding mode of the drive system;

[0025] Figure 2 shows a design draft for a drive unit of the

[0026] Drive system of Figure 1 ; Figure 3 is a flow chart for a drive system of Figures 1 and

[0027] 2 implemented control procedure;

[0028] Figure 4 shows a flow chart for a control method implemented with an embodiment of a proposed drive system, e.g., according to Figures 1 and 2, in which MOSFETs of the control electronics are activated for an active short circuit or IGBTs of the control electronics are actively clamped in order to hold the electric bicycle or another two-wheeler equipped with the drive system in a current slope in the slope hold mode of the drive system.

[0029] Figure 1 illustrates a two-wheeler in the form of an electric bicycle F with a drive system comprising an electric motor drive unit 10. The electric bicycle F has a frame 110, which here, for example, comprises a top tube, a down tube, and a seat tube, and to which the drive unit 10 is attached in the region of an intersection point of the seat tube and the down tube. Control electronics 8 and a sensor device 115 are part of the drive unit 10. Electric motors 11 and 12 (cf. Figure 2) of the drive unit 10 can be controlled via the control electronics 8, in particular to specify the level of an externally powered assist force for driving the electric bicycle F. The sensor device 115 is provided for the sensory detection of a rotational speed of the drive shaft (bottom bracket shaft) 1 of the drive unit 10. For this purpose, the sensor device 15 can comprise a rotational speed sensor, via which the rotational speed of the bottom bracket shaft 1 can be measured.A driver of the electric bicycle F can apply a driving force to the drive shaft 1 by muscle power via a pair of cranks 1A connected thereto and pedals provided thereon, to drive the electric bicycle F. Optionally, the sensor device 115 can also be provided for the sensory detection of a torque introduced at the drive shaft 1 by muscle power and can be designed, for example, with a torque sensor and / or a position sensor.

[0030] Via a belt or a chain 213 as a power transmission element, an output element of the drive unit A, for example a hollow output shaft 2 mounted coaxially to the bottom bracket shaft 1 (see Figure 2), is connected to a rear wheel 112 of the electric bicycle F in order to be able to drive the electric bicycle F. Assigned to this rear wheel 112 is, by way of example, a wheel sensor 114 for determining a driving speed of the electric bicycle F. Of course, the wheel sensor 114 can instead be provided on a front wheel 111 of the electric bicycle F.

[0031] The drive system of the electric bicycle F further comprises an operating unit 102. The operating unit 102 is, for example, attached in the area of ​​a handlebar of the electric bicycle F in Figure 2 and is connected to the control electronics 8 of the drive unit 10, typically via one or more cables. A user input can be detected via the operating unit 102 and used to control the drive unit 10. For example, the operating unit 102 comprises at least one display to inform a user of the electric bicycle F about

[0032] - the current operating status of the drive unit F, for example with regard to a set support level,

[0033] - a charge state of an energy storage device 9 supplying the drive unit 10 with electrical energy, which energy storage device 9 contains, for example, at least one (rechargeable) battery, and / or

[0034] - to inform about a set gear which specifies the ratio with which a drive torque introduced by muscle power at the input shaft 1 is transmitted to the output shaft 2 of the drive unit 10.

[0035] In the illustrated drive unit 10, the control electronics 8 additionally integrates a push-assist control. This allows the drive system to be operated in a push-assist mode, for example, by generating an operating signal on the control unit 102. A user can thus activate a push-assist function of the drive system via an operating signal, so that a user is assisted by the electric motor drive unit 10 when pushing the electric bicycle F. For this purpose, the control electronics 8 controls the first electric motor 10 to propel the electric bicycle F up to a speed of 6 km / h.

[0036] The electric bicycle 11 in Figure 1 is located on a slope H, so that a user can push the electric bicycle F up the slope H with motor assistance by operating the drive unit in the push-assist mode, and for this purpose, requires less muscle power on the handlebars of the electric bicycle F. To maintain the push-assist mode, a user must, for example, hold down a control element on the control unit 102. For example, a corresponding control element is embodied by a button to be pressed on the control unit 102. However, if a user no longer presses the control element of the control unit 102 - possibly accidentally - in order to maintain the push-assist mode, an electric motor drive unit 10 in previously known drive systems immediately ends the push-assist mode, so that no more motor assistance is applied for forward movement of the electric bicycle F.In one embodiment of the proposed solution, however, the drive unit 10 is operated immediately in a slope holding mode after deactivation of a push assistance mode, for a limited time or until deactivation by the user occurs.

[0037] In this slope-holding mode, the electric motors 10 and 11 of the drive unit 10 are controlled to hold a drive element coupled to the rear wheel 112 in the form of the drive shaft 2 in a currently assumed (rest) position. In the slope-holding mode, the electric motor drive unit 10 thus counteracts a rotation of the output shaft 2 in a reverse direction and thus a backward rolling of the rear wheel 112. The electric bicycle F is held in its position on the slope H with motor support. For appropriate control of the electric motor drive, the control electronics 8 of the drive unit 10 can interact with a speed sensor of the sensor device 115 and / or with the wheel sensor 114. The control electronics 8 can thus implement a speed control for the electric motors 11 and 12 in order to regulate a speed of the output shaft 2 to 0 revolutions per minute when the slope-holding mode is activated.

[0038] In another embodiment, in the slope hold mode, the electric motors 10 and 11 of the drive unit 10 are controlled to hold a drive element coupled to the rear wheel 112 in the form of the drive shaft 2 in a currently assumed (rest) position by the control electronics 8 implementing a permanent switching of low-side MOSFETs or high-side MOSFETs for the electric motors 11 and 12 or an active clamping of IGBTs of the control electronics 8 in order to set a speed of the output shaft 2 to 0 revolutions per minute when the slope hold mode is activated. In the slope hold mode, all MOSFETs of the control electronics 8 can be controlled for an active short circuit in order to counteract a backward rotation of the rear wheel 112 by the electric motors 11 and 12 and to prevent such backward rotation. Such a design variant can also be advantageous for an electric scooter, an e-scooter or an electric motorcycle.

[0039] Figure 2 shows a 2D design for the drive unit 10 of Figure 1, comprising two electric motors 11 and 12. The drive unit 10 has the drive shaft 1 and the output shaft 2, both of which are rotatably mounted in a housing 25 of the drive unit 10. The drive shaft 1 passes through the housing 25 and is connected on each side to a pedal crank 1A, via which a rider of the electric bicycle F can apply drive force using muscle power. The output shaft 2 protrudes from the housing 25 on only one side and is connected to a chain wheel or a toothed belt pulley in order to drive the rear wheel 112 of the electric bicycle F from there.

[0040] The drive unit 10 has a first electric motor 11 with a first rotor shaft 3 and a second electric motor 12 with a second rotor shaft 4. The two electric motors 11 and 12 are connected via the control electronics 8 and form a continuously variable electric actuator. The control electronics 8 is also connected to the energy storage device 9. This allows the output shaft 2 to be driven purely electrically via the first electric motor 11. The energy storage device 9 can also be used as a braking energy storage device when braking power flows into the drive unit 10 at the output shaft 2.

[0041] The input shaft 1, the output shaft 2, and the two rotor shafts 3 and 4 are coupled via a multi-stage planetary gear 15, which has several gear stages with a first degree of freedom and at least one planetary gear stage 16 with a second degree of freedom. The gear stages here are designed as spur gear stages. However, toothed belt gear stages are also conceivable. The present three-shaft planetary gear stage 16 comprises a sun gear 17, a ring gear 18, and a planet carrier 19 with several planetary gears 20 mounted on planetary gear pins.

[0042] The elements of the drive unit 10 are distributed here, by way of example, across three shaft trains 21, 22, and 23, all of which are arranged parallel to one another within a space defined by the housing 25. The drive shaft 1, the output shaft 2, and the second rotor shaft 4 of the second electric motor 12 are arranged coaxially on the first shaft train 21. The three-shaft planetary gear stage 16 of the multi-stage planetary gear 15 is arranged on the second shaft train 22. The first rotor shaft 3 of the first electric motor 11 is arranged on a third shaft train 23. On the first shaft train 21, the outer (hollow) output shaft 2 encloses the inner drive shaft 1 on one side of the housing 25, and the second rotor shaft 4 encloses the drive shaft 1 on the other side of the housing 25.Four gear stages 31 to 34 designed as spur gear stages serve to kinematically couple the elements of the drive unit 10, which are distributed across the three shaft trains 21, 22, and 23 and housed in the housing 25. The input shaft 1 on the first shaft train 21 is connected via a first spur gear stage 31 to a first coupling shaft 5 on the second shaft train 22. The output shaft 2 on the first shaft train 21 is connected via a second spur gear stage 32 to a second coupling shaft 6 on the second shaft train 22. The second rotor shaft 4 of the second electric motor 12 on the first shaft train 21 is connected via a third spur gear stage 33 to a third coupling shaft 7 on the second shaft train 22. This third coupling shaft also carries the sun gear 17.The first rotor shaft 3 of the first electric motor 11 on the third shaft train 23 is connected via a fourth spur gear stage 34 to the ring gear 18 of the planetary gear stage 16 on the second shaft train 22. On the second shaft train 22, the first coupling shaft 5 is connected to the planet carrier 19, the second coupling shaft 6 is connected to the ring gear 18, and the third coupling shaft is connected to the sun gear 17 of the planetary gear stage 16. Since the first rotor shaft 3 of the first motor 11 is connected to the ring gear 18 and thus to the output shaft 2, the drive unit 10 shown as an example has an output-side power split.

[0043] The first spur gear stage 31 increases the speed of the input shaft 1 to an absolute speed that is approximately three times higher than the first coupling shaft 5, which is connected to the second coupling shaft 6 via the planetary gear stage 16. The speed of the second coupling shaft 6 is transmitted to a speed of the output shaft 2 that is approximately 30% lower, e.g., lower, via the transmission ratio of the second spur gear stage 32.

[0044] In Figure 2, five arrangement levels 35, 36, 37, 38, and 39 are marked, the numbers of which increase in an axial direction 30. The axial direction 30 points from the point where the output shaft 2 exits the housing 25 into the housing 25.In Figure 2 it can be seen that the second spur gear stage 32 lies in the first arrangement plane 35 and that the planetary gear stage 16 and the fourth spur gear stage 34 lie in the second arrangement plane 36, which is offset in the axial direction 30 parallel to the first arrangement plane 35, and that the first spur gear stage 31 lies in a third arrangement plane 37, which is also offset in the axial direction 30 with respect to the second arrangement plane 36, and that the third spur gear stage 33 lies in a fourth arrangement plane 38, which is also offset in the axial direction 30 with respect to the third arrangement plane 37, and that the two electric motors 11 and 12 lie in a fifth arrangement plane 39, which is also offset in the axial direction 30 with respect to the fourth arrangement plane 38.The planetary gear stage 16 and the fourth spur gear stage 34 can be located in the same second arrangement plane 36 because the gear of the fourth spur gear stage 34 on the second shaft train 22 has a larger pitch circle radius than the ring gear 18 of the three-shaft planetary gear stage 16. As a result, the ring gear 18 finds space within this gear of the fourth spur gear stage 34 in the second arrangement plane 36.

[0045] This axial arrangement of the spur gear stages 31, 32, 33 and 34 in the vicinity of the planetary gear stage 16 on the second shaft train 22, in conjunction with the illustrated distribution of the drive elements between the three shaft trains 21, 22 and 23, results in an extremely compact multi-stage planetary gear 15.

[0046] In the first arrangement level 35 with the second spur gear stage 32, a freewheel 40 is located between the input shaft 1 and the output shaft 2, for example in the form of a sprag type freewheel. The freewheel 40 can connect the input shaft 1 directly to the output shaft 2, particularly at a maximum gear ratio. The freewheel 40 also serves as overload protection for the drive unit 10 and, on the other hand, guarantees basic mechanical functionality of the drive unit 10 in the event of problems in the electrical system, for example, a voltage drop, or problems in the control / regulation, for example, caused by a failure of one or more sensors of the sensor device 115.

[0047] For easy assembly of the remaining elements of the drive system 10 and their mounting in the housing 25, the housing 25 has four housing parts. The housing 25 consists of a main housing 26 with a center web 27 connectable or connected thereto, a motor cover 28 connectable or connected to the main housing 26 on the side of the fifth arrangement level 39, and a gearbox cover 29 connectable or connected to the main housing 26 on the side of the first arrangement level 35, through which the output shaft 2 protrudes from the housing 25.

[0048] In the illustrated drive unit 10, the control electronics 8 integrates the pushing assistance explained above as well as the option for operation in slope-holding mode. The drive system can thus be operated in pushing assistance mode, for example, by generating an operating signal using a control element on the control unit 102. A user can thus activate a pushing assistance function of the drive system via an operating signal, so that a user is assisted by the electric motor drive unit 10 when pushing the electric bicycle F up the slope H. For this purpose, the control electronics 8 controls the first electric motor 10 to propel the electric bicycle F up to a speed of 6 km / h.

[0049] If a user no longer operates the control element on the control unit 102, the push-assist mode is automatically deactivated and the electric motor drive unit 10 operates in the slope-holding mode for a predetermined period of time. In this slope-holding mode, the control electronics 8, using sensor signals from the sensor device 115 and / or the wheel sensor 114, controls the electric motor drive unit 10 in such a way that it counteracts the backward rolling of the electric bicycle F. For this purpose, the speed of the output shaft 2 is regulated to 0 revolutions per minute.

[0050] During the slope hold mode, a user can of course again actuate the control element on the control unit 102 to reactivate the push-assist mode. The electric bicycle F, which was initially held stationary on the slope H with electric motor support, can then be pushed up the slope H again with motor support. Consequently, if a user has only accidentally left the control element on the control unit 102 unactuated, the temporary operation in the slope hold mode prevents a user from having to hold the entire weight of the electric bicycle F on the slope H using muscle power alone before the control element is actuated again.

[0051] Figure 3 schematically illustrates a sequence for controlling the drive system of Figures 1 and 2.

[0052] In a first step S1, it is provided that a user has activated the pushing assistance, for example via the control unit 102, and thus the drive unit 10 is operated in the pushing assistance mode. If it is detected in a step S2 that the actuation for the pushing assistance is no longer active, for example because actuation of the control element provided for this purpose was interrupted or ended, the slope holding mode is automatically activated in a step S3. In the embodiment shown, a timer is also started at this time in order to maintain the slope holding mode only for a limited time. For the duration of the activation of the slope holding mode, a speed control for the output shaft 2 is provided in a step S4, with which the speed of the output shaft 2 is kept at 0 revolutions per minute with motor support. This prevents the electric bicycle F from rolling backwards, for example on the slope H in Figure 1.If the timer has expired in step S5, the slope hold mode is deactivated in step S6. If, however, a renewed user-activation of the push assist is detected in step S5, for example, because the user presses the control element on the control unit 102 again, the drive unit 10 switches from the slope hold mode back to the push assist mode. The electric bicycle F is thus again driven by the electric motor by rotating the output shaft 2 in the forward direction.

[0053] Figure 4 schematically illustrates an alternative sequence for controlling the drive system of Figures 1 and 2, in which, instead of the speed control in step 4*, a control of the MOSFET(s) of the control electronics 8 is provided for an active short circuit or an active clamping of the IGBT(s) of the control electronics 8 in order to prevent the rear wheel 112 from rotating backwards by the electric motors 11 and 12.

[0054] Deviating from the embodiment variant shown, a drive unit 10 with only one motor, in particular an electric motor for providing an assist force and operation in the slope holding mode can of course also be provided.

[0055] List of reference symbols

[0056] 1 drive shaft

[0057] 10 Drive unit

[0058] 11 first electric motor

[0059] 12 second electric motor

[0060] 15 planetary gears

[0061] 16 (three-shaft) planetary gear stage

[0062] 17 Sun gear

[0063] 18 ring gear

[0064] 19 planet carriers

[0065] 2 output shaft

[0066] 20 Planetary gear

[0067] 21 first shaft train

[0068] 22 second shaft train

[0069] 23 third shaft train

[0070] 25 housings

[0071] 26 Main housing

[0072] 27 Middle bridge

[0073] 28 Engine cover

[0074] 29 Gearbox cover

[0075] 3 first rotor shaft

[0076] 30 Axis direction

[0077] 31 first spur gear stage

[0078] 32 second spur gear stage

[0079] 33 third spur gear stage

[0080] 34 fourth spur gear stage

[0081] 35 first arrangement level

[0082] 36 second arrangement level

[0083] 37 third arrangement level

[0084] 38 fourth arrangement level

[0085] 39 fifth arrangement level

[0086] 4 second rotor shaft

[0087] 40 freewheel

[0088] 5 first coupling shaft

[0089] 6 second coupling shaft

[0090] 7 third coupling shaft 8 control electronics

[0091] 9 Energy storage

[0092] 102 Control panel with control element for pushing aid

[0093] 110 (bicycle) frame

[0094] 111 front wheel

[0095] 112 rear wheel

[0096] 113 Belt / Chain

[0097] 114 Wheel sensor

[0098] 115 Sensor device F Electric bicycle

Claims

Claims 1 . Drive system for a two-wheeler (F), with - a drive shaft (1), - an output element (2) for transmitting a drive force applied to the drive shaft (1) to a wheel (112) of the two-wheeler (F), - at least one motor (11, 12) for generating at least part of the driving force and - control electronics (8) for controlling the at least one motor (11, 12), characterized in that the control electronics (8) is configured to operate the at least one motor (11, 12) in a slope holding mode in which a rotation of the output element (2) is counteracted via the at least one motor (11, 12).

2. Drive system according to claim 1, characterized in that the control electronics (8) are configured to counteract, via the at least one motor (11, 12), in the slope holding mode a rotation of the output element (2) in a reverse direction of rotation as a result of a force acting on the output element (2) on the output side.

3. Drive system according to claim 1 or 2, characterized in that in the slope holding mode, an assist force is applied via the at least one motor (11, 12) in order to hold the output element (2) in a rest position.

4. Drive system according to one of claims 1 to 3, characterized in that the control electronics (8) are configured to regulate the output element (2) via the at least one motor (11, 12) to a speed of 0 revolutions per minute in the slope holding mode.

5. Drive system according to one of claims 1 to 3, characterized in that the control electronics (8) are configured to set the output element (2) to a speed of 0 revolutions per minute via the at least one motor (11, 12) in the slope holding mode by a) closing low-side MOSFETs or high-side MOSFETS of the control electronics (8) for a defined period of time or b) actively clamping IGBTs of the control electronics (8).

6. Drive system according to claim 5, characterized in that the control electronics (8) are configured to set the output element (2) to a speed of 0 revolutions per minute via the at least one motor (11, 12) in the slope holding mode by controlling the low-side MOSFETs or the high-side MOSFETs of the control electronics (8) for an active short circuit.

7. Drive system according to one of the preceding claims, characterized in that the control electronics (8) are configured to operate the at least one motor (11, 12) in a push-assist mode in which, when the two-wheeler (F) is pushed by a user, a drive torque can be transmitted to the output element (2) from the at least one motor (11, 12) with the assist force.

8. Drive system according to claim 5, characterized in that the control electronics (8) are configured to operate the at least one motor (11, 12) in the slope holding mode only after user activation of the pushing assistance mode.

9. Drive system according to claim 6, characterized in that the maintenance of the push-assist mode and the resulting transmission of a drive torque to the output element (2) requires the maintenance of a user-side actuation of an operating element and the control electronics (8) are configured to deactivate the push-assist mode and to operate the at least one motor (11, 12) in the slope holding mode in response to the termination of the actuation of the operating element.

10. Drive system according to one of the preceding claims, characterized in that the control electronics (8) are configured to operate the at least one motor (11, 12) in the slope holding mode for a predetermined period of time.

11. Drive system according to claim 8, characterized in that the drive system comprises an output element via which information about the predetermined time period and / or its expiration can be output visually and / or acoustically to a user of the two-wheeler (F).

12. Drive system according to claim 7 and according to claim 8 or 9, characterized in that the control electronics (8) are configured to operate the at least one motor (11, 12) in the slope holding mode for the predetermined period of time after the deactivation of the push assistance mode.

13. Method for controlling a drive system of a two-wheeler (F), wherein in the drive system - a drive shaft (1) is present, - an output element (2) transmits a drive force applied to the drive shaft (1) to a wheel (112) of the two-wheeler (F) and - at least one electronically controllable motor (11, 12) is provided for generating at least part of the driving force, characterized in that the at least one motor (11, 12) is operated in a slope holding mode in which a rotation of the output element (2) is counteracted via the at least one motor (11, 12).

14. A computer program product containing instructions which, when executed by at least one processor of a control unit of a drive system of a two-wheeler (F) comprising a drive unit (10), cause the at least one processor to execute a method according to claim 11.

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