Method for controlling a drive unit for a vehicle that can be operated at least temporarily by muscle power, control device, drive unit and vehicle

Abstract

A method is provided for controlling a drive unit for a vehicle that can be operated at least temporarily by muscle power, wherein a first electric motor (70) can be operated with energy from an energy store in order to support a mechanical drive by means of an adjustable output, a first rotor (71) of the first electric motor (70) and an input element (4) of the mechanical drive are mechanically operatively connected to an output element (5) via a superimposing transmission in order to drive the vehicle, and at least one sensor is designed to determine the travel speed of the vehicle. The method has the steps of determining (I) the travel speed of the vehicle via the at least one sensor; operating (II) the first electric motor (70) in a standstill mode when a standstill condition is present, said standstill condition being reached at least when the travel speed of the vehicle reaches or falls below a speed limit value; determining (III) the actual rotational angle of the first rotor (71) when the standstill condition is present; and setting (IV) an actual rotor rotation angle while taking into account a target rotational angle of the first rotor (71).

Description

[0001] Method for controlling a drive unit for a vehicle that can be operated at least temporarily with muscle power, control device, drive unit and vehicle

[0002] The present invention relates to a method for controlling a drive unit for a vehicle that can be operated at least temporarily with muscle power, a control device for carrying out a method, a drive unit for a vehicle and a vehicle.

[0003] Methods for controlling a drive unit for an e-bike are known. The e-bike can have both an electric and a mechanical drive. The assistance level of the electric drive to support the mechanical drive can be adjustable depending on, and in a specific relationship to, the rider's pedaling force. The dependence of the assistance level on the pedaling force can be uncomfortable.

[0004] The object of the present invention is to provide a method for controlling a drive unit for a vehicle that can be operated at least temporarily using muscle power, which method achieves a high level of comfort during operation of the drive unit. This object is achieved by the subject matter having the features of the independent claims. Advantageous further developments are the subject matter of the dependent claims.

[0005] In a first aspect, a method for controlling a drive unit for a vehicle that can be operated at least temporarily using muscle power is provided. A first electric motor can be operated with energy from an energy storage device to assist a mechanical drive with an adjustable power output. The adjustable power, for example an assistance power, can be adjustable, for example, depending on a cadence and the pedaling torque of the rider. The first electric motor can be formed by a synchronous machine, for example a permanent magnet synchronous machine, or an asynchronous machine. The energy storage device can have a rechargeable battery. A first rotor of the first electric motor and an input element of the mechanical drive for driving the vehicle are mechanically operatively connected to an output element via a superposition gear. The drive unit can therefore provide an eCVT system.The input element can be formed by a pedal crankshaft. The input element can have pedals. The input element can be configured to input a mechanical drive force. The mechanical drive force can be formed by a rider's pedaling force. The output element can be formed by a sprocket, a belt pulley, and a gear. At least one of the input element and the output element can be connected in a rotationally fixed manner to a gear set element of the superposition gearing. The input element can be connected in a rotationally fixed manner to a gear set element of the superposition gearing via a first freewheel. The rotational direction of the input element can be a rotational direction for which the vehicle can be moved in one direction of travel.

[0006] If two elements are mechanically operatively connected, they are directly or indirectly coupled to one another in such a way that a movement of one element causes a reaction in the other element. For example, a mechanical operative connection can be provided by a positive or frictional connection. The mechanical operative connection can correspond to the meshing of corresponding teeth of the two elements. Additional elements, such as one or more spur gear stages, can be provided between the elements. A permanently rotationally fixed connection between two elements, on the other hand, is understood to be a connection in which the two elements are rigidly coupled to one another in all intended states of the transmission. The elements can be present as individual components connected to one another in a rotationally fixed manner or as a single piece.A switching element, such as a clutch or brake, can selectively establish or break a rotationally fixed connection between two elements. A switching element can also be designed, similar to a freewheel, to establish a rotationally fixed connection in only one direction of rotation.

[0007] At least one sensor is configured to determine a driving speed of the vehicle. The sensor can be formed by a GPS module. The sensor can be formed by a speed sensor. The speed sensor can be configured to detect a wheel speed nWheel of a wheel, for example a rear wheel or a front wheel. The wheel can be a drive wheel. The method can then be configured to directly determine the driving speed of the vehicle using the detected speed. The sensor can be configured to detect a rotational movement, for example one of a speed and a rotational angle, of at least one of the input element, the output element, and the first rotor. The method can then be configured to indirectly determine the driving speed of the vehicle using the detected speed, for example an output speed n2 of the output element.

[0008] The method comprises determining the driving speed of the vehicle via the at least one sensor. The method comprises operating the first electric motor in a standstill mode when a standstill condition exists. The standstill condition can be associated with a standstill of the vehicle. The standstill condition is reached at least when the determined driving speed of the vehicle reaches or falls below a speed limit value. The method comprises determining an actual rotor rotation angle of the first rotor when the standstill condition exists. The method comprises setting an actual rotor rotation angle taking into account a target rotor rotation angle of the first rotor. The method can comprise determining the target rotor rotation angle. The target rotor rotation angle can be formed from an actual rotor rotation angle that was determined shortly before the vehicle reached the standstill condition.The method can be designed such that it operates the first electric motor in standstill mode when the standstill condition is met. In standstill mode, an actual rotor rotation angle of the first rotor can be adjustable. In standstill mode, the first electric motor can be operated in a position control mode in which the actual rotor rotation angle is set to a target rotor rotation angle or is approximated thereto. To set the target rotor rotation angle, a target rotor torque of the first electric motor can be adjustable. The method can be designed such that it operates the first electric motor in cruise mode when the standstill condition is not met. In cruise mode, the assistance power can be adjustable via at least one of a rotor speed and a rotor torque of the first electric motor.The assistance power can be adjustable in relation to at least one of the cadence and the pedaling torque. The first electric motor can be operated in a speed control mode during ferry operation, in which the assistance power can be adjusted via the rotor speed.

[0009] If a vehicle standstill is detected, the last measured actual rotor rotation angle in the ferry mode or the speed control mode of the first rotor can be used as the target rotor rotation angle for the position control mode, so that the first rotor does not rotate any further or does not rotate significantly. The target rotor rotation angle is only set to the last measured actual rotor rotation angle during the transition from the speed control mode to the position control mode. When remaining in the position control mode, the set target rotor rotation angle can be retained, even if the actual rotor rotation angle deviates due to a control deviation.

[0010] The superposition gearing can have a first planetary gear set. The input element, for example the pedal, can be rotationally fixedly connected to a first planet carrier of the first planetary gear set. The first rotor can be rotationally fixedly connected to a first sun gear of the first planetary gear set. The output element can be rotationally fixedly connected to a first ring gear of the first planetary gear set. The first ring gear can be stationary when the vehicle is stationary. If the target rotor rotation angle is maintained during stationary operation, for example by a position controller, then a fixed transmission ratio can be provided from the input element, for example the pedal, to the output element or the first ring gear.If the vehicle is moved minimally in the direction of travel, for example assuming that the method still detects that the vehicle is stationary, then the input element, for example the pedal, can be moved in the usual way according to the vehicle movement, as with a fixed mechanical transmission.

[0011] A P-controller, for example, with a proportional element P, can be used for position control in position control mode. If the driver exerts pedal force while stationary, the pedal may yield slightly due to a control deviation in the actual rotor rotation angle of the first rotor, but it will not sink any further. This can offer an advantage over a P-speed control with a speed setpoint of 0, for example. If the driver releases the pedal force, the pedal may rebound slightly. This may feel like a slight elasticity to the driver, but this is not disturbing.

[0012] The actual rotor rotation angle can be adjusted via an operating parameter, such as a voltage or current, of the first electric motor. A rotor torque of the first electric motor can be adjusted via the operating parameter. The rotor torque can, for example, be directed opposite to the drive rotation direction. The rotor torque can, for example, be directed opposite to the rider's pedaling force.

[0013] The rotor torque of the first electric motor can be limited in the position control mode, but also in the speed control mode, for example via a rotor torque limit value, so that it can only have one sign, namely such that the rotor torque acts to support the rider's pedaling force. The rotor torque can act on the input element opposite to the drive direction of rotation. This can prevent the first electric motor from rotating the input element, for example a pedal, in the drive direction of rotation, i.e. in the direction of a pedaling movement. This can also be achieved by a first freewheel, via which the input element can be rotationally fixedly connected to a gear set element of the first planetary gear set in the drive direction of rotation.

[0014] The standstill condition can be reached when the detected driving speed is less than a speed limit. This makes it possible for a standstill to be detected despite minimal movement of the vehicle. Two speed limit values ​​can be used to form a hysteresis. The standstill condition can be reached when the detected driving speed is less than a lower speed limit, for example 0.8 km / h. The method can be designed such that, when the standstill condition is met, the standstill condition is only lifted and the first electric motor is operated in ferry mode when the detected driving speed is greater than an upper speed limit, for example 1.5 km / h. This makes the detection of whether the standstill condition has been reached more stable and does not react undesirably to measurement inaccuracies.Standstill operation can have a slow and minimal, for example, sinusoidal, superimposition of the target rotor rotation angle. In this case, a minimal rotational movement of the first rotor can be provided. The minimal rotational movement can be directed alternately in the drive direction of rotation and against the drive direction of rotation. Due to the high gear ratio between the first rotor and the input element, for example, a pedal, the minimal rotational movement can be designed so that it is barely noticeable to the driver. This prevents prolonged operation of the first rotor at the same rotor angle position.

[0015] This reduces the load on the first electric motor and, if applicable, an inverter for the first electric motor; for example, the load is distributed across three phases of the first electric motor, which are formed, for example, by three electrical conductors such as stator coils or rotor coils.

[0016] The method can be designed so that, during a transition from ferry operation to standstill operation, the rotor torque of the first rotor is continuously, for example, smoothly or evenly, transferred from a rotor torque last used in ferry operation to the new value, for example, the target rotor torque in standstill operation. This reduces an uncomfortable torque jump.

[0017] The method can be configured such that the first electric motor is transferred from standstill mode to ferry mode when a travel speed is detected. The method can be configured such that, during a change from standstill mode to ferry mode, the rotor torque of the first electric motor is transferred continuously, for example, smoothly and evenly, from the target rotor torque last used in standstill mode to the new value, for example, a rotor torque of ferry mode. This reduces an uncomfortable torque jump.

[0018] The method can be configured such that the change from the shuttle mode to the standstill mode only occurs when the actual rotor speed of the first rotor is less than a rotor speed limit or reaches the rotor speed limit. The rotor speed limit can be formed by the value 0. This has the advantage that the operation of the first electric motor in the standstill mode, i.e., preventing further rotation of the first rotor, only occurs when it is desired by a strategy function in the shuttle mode of the first electric motor. This can prevent premature operation of the first electric motor in the standstill mode.

[0019] In the position control mode of the first electric motor, a starting process of the vehicle can be made possible because the electronically controlled holding, i.e. the setting of an actual rotor rotation angle, of the first rotor creates a specific, mechanically defined transmission ratio between the input element and the output element.

[0020] The drive unit can have a second electric motor EMo. A second rotor of the second electric motor can be mechanically connected to the output element, for example via a transmission. The speed nEMo of the second rotor can then be used to determine the output speed n2. The transmission can have a planetary gear set. The transmission can have an intermediate gear, for example a belt transmission or a chain transmission. The transmission can have a pre-transmission ratio iVo from the second rotor to the output element. In this respect, a fixed speed ratio of nEMo to n2 can be present via the transmission with nEMo = iVo * n2.

[0021] The superposition gearing can comprise a planetary gearing. A planetary gearing can comprise at least one planetary gear set, for example, a first planetary gear set. A planetary gear set can be configured as a positive planetary gear set or a negative planetary gear set. A planetary gear set can comprise at least one planetary gear. The planetary gear can be configured as a stepped planetary gear.

[0022] The vehicle may have a control device. The control device may have an input interface and an output interface. The input interface may be configured to input signals into the control device. The input interface may be configured to input signals from at least one of the sensors. The control device may have a computing unit, a data memory, and a working memory. The control device may be configured to process the signals from the input interface. The control device may be configured to generate signals for the output interface. The output interface may be configured to output signals from the control device. For example, the output interface may be configured to control the first electric motor.The output interface can, for example, be configured to output at least one of a voltage value and a current value, for example to control an operating parameter of the first electric motor.

[0023] The vehicle may have a drive wheel. The drive wheel may be mechanically operatively connected to the output element. The drive wheel may be mechanically operatively connected to the output element via an output gear, for example a chain drive or a belt drive. The drive wheel may have a wheel hub. The drive wheel may, for example, be mounted on the stationary component via the wheel hub. The drive wheel may, for example, be non-rotatably connected to an output element of the output gear via the wheel hub by means of a second freewheel, at least in one direction of rotation, for example opposite to the drive direction of rotation.

[0024] In one embodiment of the method, a further sensor is configured to detect braking operation of the vehicle. The method may include detecting braking operation of the vehicle. The standstill condition may be met at least when braking operation is present.

[0025] The further sensor can, for example, be formed by a pressure sensor or a contact sensor. The sensor can be provided on a braking unit, for example on a brake lever. The sensor can be configured such that braking operation is detected when the brake lever is actuated by the driver. The method can be designed such that the standstill condition exists when braking operation is detected and the driving speed of the vehicle reaches or falls below a speed limit. The method can be designed such that switching to a position control mode of the first electric motor takes place only when, in addition to a detected standstill of the vehicle, the driver actuates a braking unit, for example a brake lever.The position control mode of the first electric motor can, for example, only be used when it actually makes sense, such as when the driver is waiting at a red light with one foot on a pedal. This allows the driver to control whether the pedal can lower slowly, for example in speed control mode, or whether they want it to hold its position, for example in position control mode. This can prevent unwanted and uncomfortable provision of assistance. The speed control mode of the first electric motor can be the normal operation of the vehicle, for example with the eCVT system. The position control mode can represent a special case, for example when the vehicle is stationary.

[0026] In one embodiment of the method, a further sensor can be configured to determine an actual rotor torque of the first electric motor. The method can include determining the actual rotor torque. The method can include operating the first electric motor in standstill mode, taking the actual rotor torque into account.

[0027] The additional sensor can be formed, for example, by a torque sensor or a pressure sensor or one or more strain gauges. The additional sensor can be configured to detect the actual rotor torque. The drive device can have a first sensor and a second sensor. The first sensor can be configured to determine the vehicle speed. The second sensor can be configured to determine the actual rotor torque of the first electric motor.

[0028] The rotor torque of the first electric motor, with which the first rotor regulates the rotor rotation angle in position control mode, can be limited to a maximum permissible rotor torque limit. The rotor torque limit can be determined by a maximum operating torque for the first electric motor specified by the electric motor manufacturer. The rotor torque limit can be adjustable. This prevents the electric motor or power electronics used to operate the first electric motor from overheating. Furthermore, the required power from the battery is limited.

[0029] The method can be designed such that the first rotor begins to rotate and, for example, the pedal begins to lower when the rotor torque of the first electric motor reaches or exceeds the rotor torque limit, for example when the driver applies a high pedaling torque. During the lowering or rotating process, the first rotor can rotate in the drive direction of rotation such that a new actual rotor rotation angle is established which deviates from the target rotor rotation angle for the position control mode. The method can be designed such that, during the lowering or rotating process, the new actual rotor rotation angle forms a new target rotor rotation angle for the position control mode. Alternatively, the method can be designed such that a difference between the new actual rotor rotation angle and the target rotor rotation angle is added to the target rotor rotation angle, thus forming the new target rotor rotation angle for the position control mode.This allows the input element, such as the pedal, to remain approximately stationary, for example, at the position of the new target rotor rotation angle, rather than returning to its original position, such as the target rotor rotation angle, when the rider's high pedaling torque is removed. This allows the pedal to remain in its new position after applying a high pedaling torque and not rebound a long way.

[0030] In one embodiment of the method, a second rotor of a second electric motor for driving the vehicle can be mechanically connected to the output element via the superposition gear. The method can include switching off the second electric motor when the standstill condition is present.

[0031] The second electric motor can be operated in an assist mode, for example, when the standstill condition is not met. The method can be designed such that the second electric motor is switched off in standstill mode, for example, it is no longer operated in the assist mode. For example, the position control mode can be designed such that no actuating torque is transmitted to the second electric motor. If the standstill condition is met, for example, when the driver is at a red light and the vehicle is stationary, the vehicle is not driven by the second electric motor and therefore does not require any power.

[0032] This can be combined, in particular, with the embodiment of the method that includes detecting braking operation. For example, the driver can thereby control whether or not he wants to receive assistance from the second electric motor, such as a starting torque from a stationary vehicle.

[0033] During pedaling operation, the method can comprise detecting the actual rotor torque of the first electric motor. This can be done, for example, by measuring phase currents at the first electric motor. As a simplification, it can alternatively be assumed that the actual rotor torque is approximately equal to a rotor torque resulting from the pedaling operation of the first electric motor, for example, depending on the pedaling frequency of the rider. The actual rotor torque can have a value within a permissible range of values, for example, specified by the electric motor manufacturer. From the actual rotor torque of the first electric motor, an actual pedaling torque of the rider at the input element can be determined, for example, if the torque ratio or the transmission ratio on the first planetary gear set between the first sun gear and the first planet carrier is constant.In ferry operation, a support torque for the second rotor to support the mechanical drive can be determined and provided from the actual pedal torque thus determined.

[0034] In one embodiment of the method, the method may include determining an actual pedaling torque of the input element. The method may include operating the second electric motor in an assist mode when the standstill condition is met and the actual pedaling torque reaches or exceeds a pedaling torque limit. If the actual pedaling torque exceeds the pedaling torque limit in the position control mode of the first electric motor, i.e., when the standstill condition is met, the second electric motor may be operable in the assist mode. The second electric motor may, for example, be switched on again.If the standstill condition is reached, for example, when the driver is at a red light and the vehicle is stationary, and the driver positions the pedal at a favorable angle for starting off, for example, by turning backward, which may be possible due to the first freewheel, and places their foot on the pedal, essentially only the weight of the leg acts on the pedal. The pedal torque limit can be a value of this magnitude. Up to the pedal torque limit, the first electric motor can be operated in position control mode. Then, the second electric motor can be switched off.If the rider increases the actual pedaling torque, for example, by actively pressing the pedal to start moving, the actual pedaling torque can exceed the pedaling torque limit, and the second electric motor can be operated in support mode from this point on without delay, i.e., even before a driving speed is detected. This allows the vehicle to start moving comfortably from a standstill with the assistance of the second electric motor, which is particularly advantageous on inclines, for example. If a driving speed is subsequently detected, the first electric motor can be operated in speed control mode.

[0035] In a second aspect, a control device is provided that is configured to execute a method according to one of the preceding embodiments. The control device has at least one input interface for inputting signals into the control device and an output interface for outputting signals for controlling the drive unit.

[0036] The control device can have a user interface for inputting information, for example a limit value for determining the shutdown condition, into the control device. The control device can have an input interface and an output interface. The input interface can be configured to input signals into the control device. The input interface can be configured to input signals from at least one of the sensors. The control device can have a computing unit, a data memory, and a working memory. The control device can be configured to process the signals from the input interface. The control device can be configured to generate signals for the output interface. The output interface can be configured to output signals from the control device.For example, the output interface can be configured to control at least one of the first electric motor and the second electric motor. The output interface can be configured, for example, to output at least one operating parameter, such as a voltage value or a current value, of at least one of the first electric motor and the second electric motor.

[0037] In a third aspect, a drive unit is provided for a vehicle that can be operated at least temporarily with muscle power. A first electric motor can be operated with energy from an energy storage device to support a mechanical drive via a control device according to one of the embodiments of the second aspect with an adjustable power. A first rotor of the first electric motor and an input element of the mechanical drive are mechanically operatively connected to an output element via a superposition gear to drive the vehicle. At least one sensor is configured to determine a driving speed of the vehicle.

[0038] The sensor can be formed by at least one of a GPS module or a speed sensor, for example for detecting a speed of a wheel of the vehicle, for example a drive wheel.

[0039] In one embodiment of the drive unit, the superposition gearing can have a first planetary gear set with a first gear set element, a second gear set element, and a third gear set element. The input element can be mechanically connected to the second gear set element for inputting a drive force to the first planetary gear set. The first rotor can be mechanically connected to the first gear set element for inputting a drive force to the first planetary gear set. The output element can be mechanically connected to the third gear set element for outputting a drive force from the first planetary gear set.

[0040] The first electric motor can be configured to adjust a speed of the input element, for example, a user's pedaling frequency. This allows the drive unit to provide an electric continuously variable transmission, for example, an eCVT system. The first electric motor can be configured to adjust a gear ratio (iCVT). The first rotor can be arranged coaxially with the input element.

[0041] The first planetary gear set may include a first sun gear, a first planet carrier, a first planet pin, a first planet gear, and a first ring gear. The first sun gear may be arranged coaxially with the input element. The first sun gear may be arranged coaxially with the first rotor. The first sun gear may mesh with the first planet gear. The first planet gear may mesh with the first ring gear. The first planet gear may be rotatably mounted on the first planet pin, for example via a plain bearing, a needle bearing, or a roller bearing. The first planet gear may be formed by a stepped planet gear. The first planet pin may be attached to the first planet carrier.

[0042] The first planetary gear set can be formed by a positive planetary gear set or a negative planetary gear set. The first gear set element can be formed by the first sun gear. The second gear set element can be formed by the first planet carrier. The third gear set element can be formed by the first ring gear.

[0043] The input element can be rotationally connected to the second gear set element. The input element can be rotationally connected to the second gear set element via a first freewheel in one direction. The first freewheel can be designed such that the input element is rotationally connected to the second gear set element in the drive direction of rotation and is rotatably connected relative to the second gear set element opposite to the drive direction of rotation. The first rotor can be mechanically connected to the first gear set element via a pre-stage gearing. The pre-stage gearing can have a second planetary gear set. The second planetary gear set can be formed by a plus planetary gear set or a minus planetary gear set. The second planetary gear set can have a second sun gear, a second planet carrier, a second planet pin, a second planet gear and a second ring gear. The first rotor can be rotationally connected to the second sun gear.The second sun gear can mesh with the second planet gear. The second planet gear can mesh with the second ring gear. The second planet gear can be rotatably mounted on the second planet pin via a bearing, such as a needle bearing, a plain bearing, or a ball bearing. The second planet gear can be formed by a stepped planet gear. The second planet pin can be connected to the second planet carrier.

[0044] The first rotor, the first planetary gear set, the second planetary gear set, the input member, and the output member may be arranged coaxially. The first planetary gear set and the second planetary gear set may be arranged in an axial direction between the first electric motor and the output member. The input member may be aligned in the axial direction. The input member may extend in the axial direction through at least one of the first rotor, the first planetary gear set, the second planetary gear set, and the output member.

[0045] The drive unit can have a stationary component, for example, a bicycle frame. The second ring gear can be fixed to the stationary component. The second planet carrier can be connected in a rotationally fixed manner to the first gear set element of the first planetary gear set.

[0046] In one embodiment of the drive unit, a second rotor of a second electric motor can be mechanically operatively connected to the third gear set element for inputting a drive force into the superposition gear.

[0047] The second electric motor can be configured to set a desired torque, a desired assistance, or a desired power difference for the mechanical drive. The second electric motor can be arranged axially parallel to the input element.

[0048] The second rotor can be mechanically connected to the second gear set element or the third gear set element via a transmission. The transmission can have a third planetary gear set. The third planetary gear set can have a third sun gear, a third planet carrier, a third planet pin, a third planet gear and a third ring gear. The second rotor can be rotationally connected to the third sun gear. The third sun gear can mesh with the third planet gear. The third planet gear can mesh with the third ring gear. The third planet gear can be rotatably mounted on the third planet pin via a bearing, for example a plain bearing, a needle bearing or a ball bearing. The third planet gear can be formed by a stepped planet gear. The third planet pin can be attached to the third planet carrier.The third planetary carrier can be mechanically connected, for example, via another gear mechanism, to the third gear set element, for example, the first ring gear, or to the second gear set element, for example, the first planetary carrier, of the first planetary gear set. The third ring gear of the third planetary gear set can be fixed to the stationary component.

[0049] In a fourth aspect, a vehicle is provided with at least one drive wheel and a drive unit according to one of the embodiments of the third aspect. The vehicle can be temporarily operated using muscle power. The vehicle can be a bicycle, an e-bike, or a pedelec. The drive wheel is mechanically operatively connected to the drive unit such that the drive unit can propel the vehicle.

[0050] The drive wheel can be mechanically operatively connected to the output element. The drive wheel can be mechanically operatively connected to the output element via an output gear, for example, a chain drive or a belt drive. The drive wheel can have a wheel hub. The drive wheel can be mounted on the stationary component, for example, via the wheel hub. An output element of the output gear can be rotationally connected to the drive wheel, for example, via the wheel hub by means of a second freewheel, at least in one direction of rotation, for example, the drive direction of rotation.

[0051] Short description of the characters

[0052] Figure 1 shows a flow diagram of an embodiment of a method for controlling a drive unit of a vehicle that can be operated at least temporarily with muscle power.

[0053] Figure 2 shows a flowchart of an embodiment of the method for controlling the drive unit.

[0054] Figure 3 shows a sectional view of a schematic diagram of the drive unit.

[0055] Detailed description of embodiments

[0056] Figure 1 shows a flow diagram of an embodiment of a method for controlling a drive unit of a vehicle, in this case an e-bike, which can be operated at least temporarily using muscle power. The drive unit has an input element 4, in this case a crankshaft of a mechanical drive with pedals, an output element 5, in this case a sprocket, a first electric motor 70 with a first rotor 71 and a first stator 72, an energy storage device, in this case a battery, a superposition gear, and at least one sensor for determining a driving speed of the vehicle. The drive unit and its components are described in more detail with reference to Figure 3.

[0057] The first electric motor 70 can be operated with energy from an energy storage device to support the mechanical drive with an adjustable power. The first rotor 71 of the first electric motor 70 and the input element 4 of the mechanical drive are mechanically operatively connected to the output element 5 via a superposition gear to drive the vehicle. The method comprises, in a first step, determining the driving speed of the vehicle. In a second step, the method comprises operating the first electric motor 70 in a standstill mode when a standstill condition exists. The standstill condition is reached at least when the driving speed of the vehicle reaches or falls below a speed limit value. In a third step, the method comprises determining an actual rotor rotation angle of the first rotor 71 when the standstill condition exists.In a fourth step, the method includes adjusting the actual rotor rotation angle, taking into account a target rotor rotation angle of the first rotor 71. The method then begins again with the first step. This can prevent a pedal of the crankshaft from sinking when the vehicle is stationary and the driver of the vehicle rests a foot on the pedal without intending to drive the vehicle.

[0058] Further details of the process and the drive unit are described below.

[0059] In a further embodiment, the method comprises, in a fifth step, detecting braking operation of the vehicle. The standstill condition is met at least when braking operation is present. This ensures the operation of the first electric motor 70 in standstill mode when the driver requests braking. The fifth step is performed here after the first step. After the fifth step, the method continues with the second step according to the first embodiment.

[0060] In a further embodiment, the method comprises, in a sixth step, determining an actual rotor torque of the first electric motor 70. The operation of the first electric motor 70 in standstill mode takes into account the actual rotor torque. The actual rotor torque is limited to a maximum permissible value that is not exceeded. This prevents overheating of the first electric motor 70. The sixth step is carried out here after the first step. After the sixth step, the method continues with the second step according to the first embodiment. In a further embodiment, the drive unit has the second electric motor 80 with a second rotor 81 for inputting a drive force into the superposition gear. The second rotor 81 is operatively connected mechanically to the output element 5 via a transmission gear and the superposition gear.In this embodiment, the method includes, in a seventh step, switching off the second electric motor 80 when the standstill condition is met. This leads to energy-saving operation of the drive unit when the vehicle is stationary.

[0061] In an eighth step, the method comprises determining an actual pedaling torque of the input element 4. In a ninth step, the method comprises operating the second electric motor 80 in an assistance mode when the standstill condition exists and the actual pedaling torque reaches or exceeds a pedaling torque limit. This allows the driver's attempt to start to be assisted even before a vehicle speed is detected. The seventh step is carried out here after the first step. After the ninth step, the method continues with the second step according to the first embodiment.

[0062] Figure 2 shows a flowchart of at least one of the preceding embodiments of the method for controlling the drive unit. As previously described, the method begins with the first step, i.e., determining the driving speed. Subsequently, based at least on the driving speed of the vehicle, it is checked whether the vehicle is stationary. If the vehicle is stationary, the first electric motor 70 is operated in stationary mode. Otherwise, the first electric motor 70 is operated in a ferry mode, in which the first electric motor 70 provides the assist power.

[0063] Figure 3 shows a sectional view of a schematic diagram of the drive unit. The drive unit can be controlled using a method according to one of the preceding embodiments. The drive unit has all the features of at least one of the preceding embodiments. The superposition gear is formed by a first planetary gear set 10. The drive unit further comprises a pre-stage gear formed by a second planetary gear set 20, a rear wheel as the drive wheel, which is operatively connected to the output element 5 via an output gear, in this case a chain drive, to drive the vehicle, and a stationary component 9, which in this case is formed by a bicycle frame.

[0064] The first rotor 71, the first planetary gear set 10, the second planetary gear set 20, the input member 4, and the output member 5 are arranged coaxially. The first planetary gear set 10 and the second planetary gear set 20 are arranged in an axial direction between the first electric motor 70 and the output member 5. The input member 4 extends in the axial direction through the first rotor 71, the first planetary gear set 10, the second planetary gear set 20, and the output member 5.

[0065] The first planetary gear set 10 has a first sun gear, a first planet carrier, a number of first planet pinions, a number of first planet gears, and a first ring gear. The first sun gear meshes with the first planet gears. Each of the first planet gears is rotatably supported on one of the first planet pinions. The first planet pinions are attached to the first planet carrier. The first planet gears mesh with the first ring gear. The second planetary gear set 20 has a second sun gear, a second planet carrier, a number of second planet pinions, a number of second planet gears, and a second ring gear. The second sun gear meshes with the second planet gears. Each of the second planet gears is rotatably supported on one of the second planet pinions. The second planet pinions are attached to the second planet carrier. The second planet gears mesh with the second ring gear.

[0066] The input element 4 is rotationally fixedly connected to the first planet carrier. The first ring gear is rotationally connected to the output element 5. As a result, the input element 4 is mechanically operatively connected to the output element 5 for driving the vehicle. In one embodiment, the input element 4 is rotationally fixedly connected to the first planet carrier via a first freewheel 41 in the drive direction of rotation. The input element 4 is then rotatable relative to the first planet carrier via the first freewheel 41 against the drive direction of rotation. The first stator 72 is fixed to the stationary component 9. The first rotor 71 is rotationally connected to the second sun gear. The second ring gear is fixed to the stationary component 9. The second planet carrier is rotationally connected to the first sun gear. As a result, the first rotor 71 is mechanically operatively connected to the output element 5 for driving the vehicle.

[0067] An output element, in this case an output sprocket, of the output gear is connected to the drive wheel in a rotationally fixed manner in the drive direction via a second freewheel 42. The drive wheel is rotatably mounted on the stationary component 9 via a bearing unit. The drive wheel is thus configured to drive the vehicle.

[0068] The drive unit comprises the second electric motor 80 with the second rotor 81 and a second stator 82. The second stator 82 is fixed to the stationary component 9. The second rotor 81 is arranged axially parallel to the first rotor 71. The second rotor 81 is arranged in the same plane as the first rotor 71 in the axial direction. The second rotor 81 is mechanically connected to the first ring gear via the transmission gear.

[0069] The transmission includes a third planetary gear set with a third sun gear, a third planet carrier, a number of third planet pinions, a number of third planet gears, and a third ring gear. The third sun gear meshes with the third planet gears. Each of the third planet gears is rotatably mounted on one of the third planet pinions. The third planet pinions are attached to the third planet carrier. The transmission further includes an intermediate gear, for example, a belt drive, with an input element and an output element.

[0070] The second rotor 81 is rotationally fixed to the third sun gear. The third ring gear is fixed to the stationary component 9. The third planet carrier is rotationally fixed to the input element of the intermediate gear. The output element of the intermediate gear is rotationally fixed to the first ring gear. Reference numeral

[0071] 4 Input element

[0072] 5 Output element

[0073] 9 Stationary component

[0074] 10 First planetary gear set

[0075] 20 Second planetary gear set

[0076] 41 First freewheel

[0077] 42 Second freewheel

[0078] 70 First electric motor

[0079] 71 First rotor

[0080] 72 First stator

[0081] 80 Second electric motor

[0082] 81 Second rotor

[0083] 82 Second stator

[0084] I Determining the vehicle's driving speed

[0085] 11 Operating the first electric motor in a standstill mode

[0086] III Determining the actual rotor rotation angle of the first rotor

[0087] IV Setting an actual rotor rotation angle taking into account a target

[0088] Rotor rotation angle

[0089] V Detection of vehicle braking

[0090] VI Determining the actual rotor torque of the first electric motor

[0091] VII Switching off the second electric motor

[0092] VIII Determining the actual pedal torque of the input element

[0093] IX Operating the second electric motor in a support mode

Claims

Patent claims 1. Method for controlling a drive unit for a vehicle that can be operated at least temporarily with muscle power, wherein - a first electric motor (70) is operable with energy from an energy storage device to support a mechanical drive with an adjustable power, - a first rotor (71) of the first electric motor (70) and an input element (4) of the mechanical drive for driving the vehicle are mechanically connected to an output element (5) via a superposition gear, - at least one sensor is configured to determine a driving speed of the vehicle, the method comprising: - Determining (I) the driving speed of the vehicle via the at least one sensor, - operating (II) the first electric motor (70) in a standstill mode when a standstill condition exists, which is reached at least when the determined driving speed of the vehicle reaches or falls below a speed limit value, - determining (III) an actual rotor rotation angle of the first rotor (71) when the standstill condition is present, and - Setting (IV) the actual rotor rotation angle taking into account a target rotor rotation angle of the first rotor (71).

2. Method according to claim 1, characterized in that a further sensor is arranged to detect a braking operation of the vehicle, the method comprising: - Detecting (V) a braking operation of the vehicle, and wherein the standstill condition is at least reached when the braking operation is present.

3. Method according to one of the preceding claims, characterized in that a further sensor is set up to determine an actual rotor torque of the first electric motor (70), the method comprising: - Determine (VI) the actual rotor torque, and - Operating (II) the first electric motor (70) in standstill mode taking into account the actual rotor torque.

4. Method according to one of the preceding claims, characterized in that a second rotor (81) of a second electric motor (80) for driving the vehicle is mechanically connected to the output element (5) via the superposition gear, and The procedure includes: - Switching off (VII) the second electric motor (80) when the standstill condition is met.

5. Method according to claim 4, characterized in that the method comprises: - determining (VIII) an actual pedal torque of the input element (4), and - Operating (IX) the second electric motor (80) in an assistance mode when the standstill condition exists and the actual pedaling torque reaches or exceeds a pedaling torque limit value.

6. Control device which is configured to carry out a method according to one of the preceding claims, wherein the control device has at least one input interface for inputting signals into the control device and an output interface for outputting signals for controlling a drive unit.

7. Drive unit for a vehicle that can be driven at least temporarily by muscle power, wherein - a first electric motor (70) is operable with energy from an energy storage device to support a mechanical drive via a control device according to claim 6 with an adjustable power, - a first rotor (71) of the first electric motor (70) and an input element (4) of the mechanical drive for driving the vehicle are mechanically connected to an output element (5) via a transmission gear, and - at least one sensor is set up to determine a driving speed of the vehicle.

8. Drive unit according to claim 7, characterized in that - the superposition gear has a first planetary gear set (10) with a first gear set element, a second gear set element and a third gear set element, - the input element (4) is mechanically connected to the second gear set element for inputting a drive force into the first planetary gear set (10), - the first rotor (71) is mechanically connected to the first gear set element for inputting a drive force into the first planetary gear set (10), and - the output element (5) is mechanically connected to the third gear set element for outputting a drive force from the first planetary gear set (10).

9. Drive unit according to claim 7 or 8, characterized in that a second rotor (81) of a second electric motor (80) is mechanically operatively connected to the third gear set element for inputting a driving force into the superposition gear.

10. A vehicle having at least one drive wheel and a drive unit according to one of claims 7 to 9, wherein the vehicle is temporarily operable by muscle power, and wherein the drive wheel is mechanically operatively connected to the drive unit such that the drive unit can move the vehicle.

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