Drive system for an electric bicycle, and method for determining the presence of a slip situation

Abstract

A drive system (2) for an electric bicycle (1), having a bottom bracket shaft (21) for generating a drive power for a muscle-powered locomotion of the electric bicycle, at least one drive motor (23) for providing an assistance power generated by external force in addition to the drive power at the bottom bracket shaft, the at least one drive motor having a rotor, and an electronic control unit which is provided and configured to control the supply of assistance power. The electronic control unit is provided and configured to detect the rotor rotational speed (U) over time, to determine an increase in the rotor rotational speed in at least one first and second time window (Z1, Z2, Z3), and to determine, on the basis of the increase in the rotor rotational speed, whether a slip situation is present and / or what intensity the slip has.

Description

[0001] Brose Antriebstechnik GmbH & Co.

[0002] Limited partnership, Berlin Sickingenstraße 29-38 10553 Berlin

[0003] BRG192 / 2024 049 EM

[0004] Drive system for an electric bicycle and method for determining the existence of a slippage situation

[0005] Description

[0006] The proposed solution relates to a drive system for an electric bicycle according to claim 1, claim 6 and claim 11, a method for determining the existence of a slip situation according to claim 14, a method for operating a drive system for an electric bicycle according to claim 15, a computer program product according to claim 16 and an electric bicycle according to claim 17.

[0007] An electric bicycle has a drive system with at least one electric motor, which can be used to provide assistance for the bicycle's movement in addition to the power provided by the rider. This allows the rider to achieve faster movement with less effort.

[0008] The drive power and the assistance power are transferred to a wheel, for example, a rear wheel, of the e-bike to enable forward movement by the wheel rolling on the surface over which the e-bike is moving. If the surface does not provide sufficient friction for the wheel or if the wheel loses contact with the surface, slippage can occur. In this case, the wheel rotates without achieving corresponding forward motion. In particular, the rotational speed of a wheel can be affected by BRG192 page 2.

[0009] The drive power and / or support power of the driven wheel in a slipping situation may be greater than the rotational speed of a non-driven wheel. It is desirable to adjust the support power in such a slipping situation.

[0010] To adjust the level of assistance to the slippage situation, an electronic control unit of the e-bike can determine whether slippage is present. For example, on an e-bike, this can be done by comparing the rotational speeds of the wheels. If the difference, for example, between a front and a rear wheel, exceeds a certain tolerance, the level of assistance can be reduced by decreasing the motor torque of at least one of the drive motors. This reduction can eliminate the slippage.

[0011] Sensors are typically used to determine the wheel speeds, which incurs additional costs and requires more effort during the assembly of the e-bike. For example, a significant change in motor speed, i.e., an internal parameter of the drive system, can also indicate a slippage situation, as described in publication EP 2 650 202 A1.

[0012] Against this background, the proposed solution is based on the task of providing a drive system that reliably detects a slip situation in a simple way.

[0013] According to a first aspect of the proposed solution, the problem is solved by a drive system for an electric bicycle. This system has a bottom bracket axle for generating drive power for muscle-powered propulsion of the electric bicycle and at least one drive motor for providing externally generated assistance power in addition to the drive power at the bottom bracket axle, wherein the at least one drive motor has a rotor. The drive system further includes an electronic control unit designed and configured to control the provision of the assistance power.

[0014] The electronic control unit is designed and configured to record rotor speed over time, to determine an increase in rotor speed in at least a first and second time window, and, depending on the increase in rotor speed, to determine whether a slip situation exists and / or what the intensity of the slip is.

[0015] 2024 049 EM BRG192 Page 3

[0016] This allows slippage to be reliably detected, enabling the user to operate the e-bike with increased safety. The solution requires no additional effort for implementation due to extra components, as the determination of slippage and its intensity can be based on internal or existing components. Because no additional components are needed, the drive system can provide robust detection with a minimum of potentially failure-prone sensors.

[0017] A rider torque can be applied to the bottom bracket axle via a rider cadence. This torque can be applied to the bottom bracket axle, for example, via a crank arm (possibly in conjunction with a pedal). The rider cadence (alternatively referred to as pedaling cadence) can be expressed as the number of revolutions of the bottom bracket axle per unit of time. The at least one drive motor can be, for example, an electric motor. The drive power and the assistance power can, individually or together, propel the e-bike.

[0018] The at least one drive motor can have a stator in addition to the rotor, relative to which the rotor is rotatably mounted. The rotor can rotate at a specific speed relative to the stator to generate the assist power. For example, the assist power can be specified via at least one operating parameter of the drive motor, such as motor current, motor speed, motor torque, motor power, or an assist factor.

[0019] The control unit can thus regulate the provision of support power, for example, by specifying at least one operating parameter. The support power can be determined based on the drive power. For example, rider torque and / or rider cadence can be used as the basis for this.

[0020] Determining whether a slippage situation exists can be done independently of the specific method used to determine the support power. Since a slippage situation can cause an increase in rotor speed, monitoring the rotor speed over time can provide a reliable data source for determining whether a slippage situation exists. A variety of time windows can be used for this purpose, within which the increase in rotor speed can be observed.

[0021] 2024 049 EM BRG192 page 4 is determined. The time windows can be separated from each other by a predetermined interval (in time). By using multiple time windows, the determination of whether a slippage situation exists can be made even more reliably.

[0022] Determining the intensity of slip can be used to prepare an appropriate response to the slip situation. While determining the slip situation only allows the conclusion that there is no static friction between the driven wheel and the surface, determining the intensity of the slip can, for example, allow conclusions to be drawn about the magnitude of any remaining sliding friction between the driven wheel and the surface. Furthermore, determining the intensity of the slip can also include the duration of the slip situation.

[0023] In one embodiment, the at least one first and second time windows have different lengths. For example, the at least one first time window can be shorter than the at least one second time window. An extension of the at least one second time window compared to the at least one first time window can be triggered, for example, if an increase in rotor speed is detected within the at least one first time window that exceeds a predefined trigger threshold. This is because such an increase can indicate the onset of a slippage situation. Determining the increase in rotor speed within the at least one second time window can be used to verify this indication. For this purpose, the at least one second time window can be longer than the at least one first time window.It is also conceivable and possible that the at least one second time window is shorter than the at least one first time window, for example, to avoid delaying the determination of the hatching situation through a (longer) measurement. The time windows could, for example, have a length of less than 0.10 seconds, in particular 0.03 to 0.06 seconds, and most especially 0.04 seconds.

[0024] In one embodiment, the electronic control unit is designed and configured to determine that a slip situation exists when the increase in rotor speed exceeds a threshold value (e.g., 15,000 revolutions per second) in at least one of the time windows. This threshold value can be fixed or dynamically adaptable to the driving situation. For example, the electronic control unit can be designed and configured to adjust the threshold value depending on the state of a gearshift in the drive system.

[0025] 2024 049 EM BRG192 Page 5

[0026] The gear system can be designed and configured to provide a variable gear ratio in the form of different gears for transmitting drive power and / or assistance power from the bottom bracket axle to the driven wheel. For example, the user can select the gear ratio. The gear system can be electronically controlled and / or select a gear automatically. A gear system state can, for example, be a high or a low gear. In a low gear, a higher threshold value can be set because a faster increase in rotor speed without slippage is possible than in a high gear. The state of the (electronic) gear system can be estimated by the electronic control unit. This estimate can be based, in particular, on the rotor speed and the speed of the e-bike.This eliminates the need for communication between the electronic control unit and the electronic circuit.

[0027] In one embodiment, the electronic control unit is designed and configured to determine whether a slip situation exists, depending on whether the motor current, which can be applied to the at least one drive motor to generate the auxiliary power, exceeds a predefined threshold and / or whether the actual motor current profile deviates from a target motor current profile. In addition to the rotor speed, the motor current can thus be used to determine whether a slip situation exists. This embodiment is based, among other things, on the consideration that a reaction at the drive motor to the slip situation is particularly useful if the auxiliary power is at least partially responsible for the slip situation. The threshold for the motor current can be, for example, 5 A or 10 A.At such a threshold value, the support power can be so high that it can cause slippage. The threshold value can, in particular, be derived from a target current curve for the motor.

[0028] Another consideration underlying this design is that a slippage situation can occur, in particular, if the motor current draw is increased within a short period of time due to an action by the rider, for example, to accelerate the e-bike quickly. Such a sudden increase can transmit a high force between the wheel and the road surface, so that, as a consequence of the increased motor current, the loss of traction can occur.

[0029] 2024 049 EM BRG192 Page 6

[0030] Static friction can occur. Therefore, if there is a prior increase in motor current draw (above the specified threshold), this can indicate a slippage situation triggered by this friction. During a slippage situation, the assistance power, especially at the rear wheel, can drop (because the wheel spins relatively freely, especially when negligible sliding friction is disregarded). This means that the rotor speed can increase at the beginning of a slippage situation. With a sharp increase in rotor speed, the motor current may not be immediately regulated (by a current regulator unit of the electronic control unit), so the motor torque can decrease with increasing rotor speed. Consequently, the motor current can also decrease at the beginning of a slippage situation.The current regulator unit can be configured and designed to increase the motor voltage as the slippage progresses, in order to compensate for the drop in motor current. Furthermore, the rider's pedaling torque may decrease during slippage because the rider recognizes the situation and applies less drive power. Therefore, the target motor current profile may decrease simultaneously with the decrease in actual motor current.

[0031] Alternatively or additionally, the actual motor current profile can be compared with a target profile. This alternative or additional design is based, among other things, on the consideration that the motor current may not be immediately regulated (by the current control unit of the electronic control unit) during a sharp increase in rotor speed, so that deviations between the actual and target profiles may occur. These deviations may, in particular, exceed a tolerance threshold. The tolerance threshold may be, for example, 10%, 50%, or, most importantly, 70% of the target profile value. For example, the electronic control unit may be designed and configured to monitor the actual profile over at least one first and / or at least one second time window (or any further time window, if necessary).The actual trend (which has at least one overlap with the first and / or at least one second time window) should be recorded and compared with the target trend. A deviation of the actual trend from the target trend can be determined by whether the comparison yields a deviation (possibly averaged over the time window(s)) that exceeds a predefined threshold (such as the deviation tolerance threshold).

[0032] In one embodiment, the electronic control unit is designed and configured to detect whether an increase in rotor speed occurs on a surface in the

[0033] 2024 049 EM BRG192 Page 7

[0034] The play in the drive system can be caused, for example, by a transmission element that transfers the assist power from the rotor to the rear wheel not engaging directly with a positive connection. Furthermore, play may be present after the freewheel mechanism of the e-bike is engaged in a freewheel mode, where the pedals can rotate without generating drive power at the bottom bracket axle. This play may be designed in such a way that it must first be overcome to transition the freewheel mechanism from freewheel mode to a transmission mode, in which the bottom bracket axle allows the transmission of drive power and assist power. Another example of a freewheel that can cause play in the drive system is a motor freewheel.If the drive motor is not rotating, the pedal cranks (to generate the drive force) can be turned without engaging the motor. If assistance is required in such a situation, the motor's freewheel is overcome by using up its play. Only when this play is exhausted can the bottom bracket axle be subjected to the assistance power. This play can also or alternatively result from the need to accelerate the drive motor from a standstill to a speed that matches the bottom bracket axle's operating speed.

[0035] Such play in the drive system can cause the rotor speed to increase sharply within a short period. The electronic control unit can detect this, for example, by observing that the rotor speed is higher in at least one initial time window (where the sharp increase occurs) than in at least one subsequent time window. Alternatively or additionally, the electronic control unit can be designed and configured to detect the presence of play by identifying a rise and fall in rotor speed within a predefined maximum play period.

[0036] The electronic control unit can be designed and configured to assume, starting from a situation where the rotor speed and / or motor torque is zero, that a backlash must be overcome before the support power can be provided. The electronic control unit can use one or more of the following options to manage this backlash and avoid controlling the at least one drive motor based on a rotor speed determined by the backlash being consumed: The electronic control unit can ignore any increase in motor speed for a predetermined consumption period. This increase can then be disregarded when controlling the at least one drive motor.

[0037] 2024 049 EM BRG192 Page 8. According to another option, the increase in motor speed can be ignored until the rotor speed is (almost) synchronous with the rider's cadence. In this case, the gear ratio of a motor gearbox can be taken into account. A third option is that the electronic control unit is designed and configured to recognize at least one standard signal waveform. A standard signal waveform could, for example, be a waveform showing the increase in motor speed when the assistance power is engaged. The electronic control unit can include an electronic storage unit in which at least one standard signal waveform is stored. With the aforementioned options, the electronic control unit can be enabled to filter out any play in the rotor speed.

[0038] According to a second aspect of the claimed solution, the problem is solved by a drive system for an electric bicycle, which has a bottom bracket axle for generating drive power for muscle-powered propulsion of the electric bicycle and at least one drive motor for providing externally generated support power in addition to the drive power at the bottom bracket axle. An electronic control unit of the drive system is provided and configured to control the provision of the support power and to detect the presence of slippage.

[0039] Furthermore, according to an initial design, the electronic control unit is intended and configured to provide support for a predetermined support period after the end of the slippage situation, with a support value that is at least predetermined.

[0040] According to a second embodiment, the electronic control unit is designed and configured to provide the support power in a first operating mode by controlling a motor torque and in a second operating mode by controlling a motor speed, and to select the second operating mode after recognizing that a slip situation exists.

[0041] According to a third embodiment, the electronic control unit is designed and configured to provide at least one option for a level of assistance that can be selected by the driver, and, after recognizing that a slip situation exists, to adjust the assistance level according to the at least one option.

[0042] 2024 049 EM BRG192 Page 9

[0043] The electronic control unit is designed according to one or more of the first, second, and third configurations. These configurations are described in more detail below.

[0044] According to the first design, the electronic control unit can detect when a slipping situation has ended. In principle, in this situation, the e-bike can continue to move normally using drive power and any additional support power that may be provided. Providing a predetermined support period, during which support power of at least a specified level is available, can improve the riding experience during the transition from a slipping situation to normal riding.

[0045] In particular, the crank arms may have been forced into a dead-end position by slippage, where the rider cannot adjust them by applying purely vertical force to the pedals. Even within a range of up to 10° (measured around an axis through the bottom bracket axle) of such a dead-end position, it can be difficult for the e-bike rider (especially on a slope or hill) to efficiently operate the crank arms to regain momentum. By providing assistance, which has at least a predefined level of support, this can be made easier for the rider, because the additional assistance may require less power to adjust the crank arms.

[0046] The specified support period can be, for example, less than 0.50 seconds, and in particular less than 0.3 seconds. A suitable length for the support period is, for example, 0.25 seconds.

[0047] In principle, the assistance output can be controlled by the electronic control unit via any operating parameter of the at least one drive motor. The first operating mode according to the second configuration, in which control is achieved via the motor torque, can be advantageous for coupling the assistance output to the rider's torque. For example, the motor torque can be proportional to the rider's torque (e.g., always twice as high). The motor speed can then be a dependent variable determined by the motor torque (depending on the selected gear ratio of a motor gearbox). The rider can thus experience a high level of performance with minimal effort.

[0048] 2024 049 EM BRG192 Page 10. With simple force input, which is converted into drive power, and a support power twice as large as the drive power, for example, three times the effect of the force input can be achieved.

[0049] The second operating mode according to the second embodiment, in which control is via the motor speed, can be selected after the detection of a slip situation and specifically after the end of the slip situation.

[0050] In one embodiment, the electronic control unit is designed and configured to maintain the second operating mode for at least a predetermined switching period. This allows the use of the second operating mode to be limited in time before, for example, the first, potentially more advantageous, operating mode or another operating mode is selected again.

[0051] In a further embodiment, the electronic control unit is designed and configured to initially specify an engine speed after selecting the second operating mode. This engine speed is based on the engine speed before the slippage situation was detected. This ensures a consistent driving experience. In principle, the specified engine speed can be identical to the engine speed used before the slippage situation was detected. During the slippage situation, the engine speed may be undesirably high, so specifying the engine speed before the slippage situation was detected approximates the engine speed actually required and expected by the driver.

[0052] In one embodiment, the electronic control unit is designed and configured to specify the motor speed for a predetermined transition period. This predetermined motor speed can thus serve as a starting point for an adjusted motor speed, which, in the second operating mode, may be set after the transition period has elapsed, for example, based on the rider's pedaling frequency. Therefore, the initial setting can be adjusted during subsequent operation.

[0053] The level of assistance can generally be reduced by a damping factor of less than 1 (for example, 0.5) after the detection of a slip situation. In particular, the motor torque can be reduced by the damping factor. The damping factor can also be based on the intensity of the slip. With at least one option according to the third configuration, the driver can select

[0054] 2024 049 EM BRG192 Page 11 states that the level of assistance is adjusted after a slippage situation is detected. Without selecting at least one option, the level of assistance can be maintained, for example, even if a slippage situation is detected. Alternatively, several options for the level of assistance can be provided, which can be selected by the rider. A first option, for example, might allow a greater adjustment of the level of assistance in the event of a slippage situation being detected than a second option. The options can be presented to the rider for selection via a display, for example, in the form of keywords such as "damp roots" (first option) or "sand course" (second option).To display and select at least one option, an input device or at least a (wireless) interface to an external input device, such as a Bluetooth interface to a smartphone, can generally be provided.

[0055] In one embodiment, the electronic control unit is designed and configured to ensure that the motor current remains above a minimum value for at least a limited period after a slip situation is detected. This ensures that a minimum level of assistance is guaranteed even if the slip situation is only brief. Furthermore, it allows the assistance level to be increased more quickly after the slip situation ends, without having to overcome any backlash.

[0056] In one embodiment, the electronic control unit is designed and configured to classify the intensity of slip into at least two categories and to select the second operating mode based on this classification and / or to adjust the support level accordingly. A first category could, for example, encompass slip with high sliding friction, and / or a second category could encompass slip of short duration. The electronic control unit can be designed and configured to omit any change in support level when the intensity of slip is classified into one of these categories (just as when no slip is present). However, after the slip situation has ended, support level can be provided for a predetermined support period, with at least a predefined support value.This provision can also be made dependent on the classification of the hatching intensity.

[0057] 2024 049 EM BRG192 Page 12

[0058] A third category can encompass slippage with low sliding friction and / or a fourth category can encompass slippage of prolonged duration. The intensity of the slippage can be classified into multiple categories simultaneously, for example, the first and fourth categories. If the slippage intensity is classified into the third or fourth category, the second operating mode (e.g., after the slippage has ended) can be selected and / or the support level can be adjusted (according to at least one option).

[0059] Therefore, not every slippage situation necessarily leads to the reactions of the electronic control unit prescribed by the second aspect. Rather, the reactions can be made dependent on the classification of the slippage intensity.

[0060] Features and benefits described in connection with the first aspect can also apply to the second aspect.

[0061] According to a third aspect of the proposed solution, the problem is solved by a drive system for an electric bicycle, which has a bottom bracket axle for generating drive power for muscle-powered propulsion of the electric bicycle and at least one drive motor for providing externally generated support power in addition to the drive power at the bottom bracket axle, wherein the at least one drive motor has a rotor. The drive system has an electronic control unit designed and configured to control the provision of the support power and a speed control unit for detecting the rotor speed.

[0062] The electronic control unit is designed and configured to regulate the assistance power in such a way that the increase in rotor speed does not exceed a maximum value. Limiting the increase in rotor speed in this way prevents an undesirable reaction of the drive system in a slipping situation. This maximum value can correspond to a rotor speed value for the maximum possible acceleration of the e-bike. Alternatively, the maximum value can be preset.

[0063] In one embodiment, the drive system has a gear shift that provides a variable gear ratio in the form of different gears for transmitting the drive power and / or the support power from the bottom bracket axle to a driven wheel, wherein the electronic control unit

[0064] 2024 049 EM BRG192, page 13, is designed and configured to specify the maximum value depending on the gear. For this purpose, the electronic control unit can be coupled with the gearshift so that it can maintain the gearshift state. Alternatively, the gear can be estimated by the electronic control unit. This estimate can be based on the rotor speed (possibly before a slippage situation is detected) and the e-bike's speed.

[0065] In one embodiment, the drive system includes an input device for recording a maximum value input, with the electronic control unit being designed and configured to specify the maximum value depending on the input. The input device allows a user to adapt the drive system's response to a slippage situation to their needs. For example, the input device can provide the user with a selection of at least two maximum values ​​(e.g., in the form of keyword-like scenarios such as "sand parkour" or "damp roots"), from which the user selects one. Alternatively, the user can directly enter a maximum value as a number (e.g., 10,000 revolutions per second squared).

[0066] Features and benefits described in connection with the first and second aspects can also apply to the third aspect.

[0067] According to a fourth aspect of the proposed solution, the problem is solved by a procedure for determining whether a slippage situation exists in an electric bicycle. The procedure comprises the following steps:

[0068] - Generating drive power for muscle-powered propulsion of the electric bicycle at a bottom bracket axle of the electric bicycle,

[0069] - Providing externally generated support power in addition to the drive power at the bottom bracket axle by at least one drive motor,

[0070] - Determining the rotor speed of a rotor of at least one drive motor,

[0071] - Determining an increase in rotor speed in at least one first and second time window and

[0072] - Determine whether a slippage situation exists, depending on the increase in rotor speed.

[0073] Features and advantages described in connection with the first to third aspects may also apply to the procedure according to the fourth aspect.

[0074] 2024 049 EM BRG192 Page 14

[0075] According to a fifth aspect of the proposed solution, the problem is solved by a procedure for operating a drive system for an electric bicycle after detecting a slip situation, which includes the following steps:

[0076] - Generating drive power for muscle-powered propulsion of the electric bicycle at a bottom bracket axle of the electric bicycle,

[0077] - Providing externally generated support power in addition to the drive power at the bottom bracket axle by at least one drive motor.

[0078] According to an initial design, after the end of the slippage situation, a support service is provided for a predetermined support period, which has at least a predetermined support value.

[0079] According to a second embodiment, the support power is provided in a first operating mode by controlling a motor torque and in a second operating mode by controlling a motor speed, whereby the second operating mode is selected after recognizing that a slip situation exists.

[0080] According to a third embodiment, at least one option for a level of support is provided, which can be selected by the driver, whereby after recognizing that a slip situation exists, the support level is adjusted according to the at least one option.

[0081] The procedure is designed according to one or more of the first, second and third configurations.

[0082] Features and advantages described in connection with the first to fourth aspects may also apply to the procedure according to the fifth aspect.

[0083] Furthermore, the proposed solution includes a computer program product containing instructions which, when executed by at least one processor of an electronic control unit for a drive system of an electric bicycle, cause the at least one processor to execute a procedure according to the third or fourth aspect.

[0084] The proposed solution also includes an electric bicycle with a drive system according to the first or second aspect.

[0085] 2024 049 EM BRG192 Page 15

[0086] The attached figures illustrate possible implementation variants of the proposed solution.

[0087] Here they show

[0088] Figure 1 shows a schematic view of an electric bicycle;

[0089] Figure 2 shows a schematic of a drive system;

[0090] Figure 3 shows exemplary curves of motor current, driver torque, and rotor speed over time; and

[0091] Figure 4 shows further exemplary curves of motor current, driver torque and rotor speed over time.

[0092] Figure 1 shows a schematic view of an electric bicycle 1 with a front wheel 10 and a rear wheel 11. The rear wheel 11 is connected via a transmission element 12 (e.g., a chain) to a drive system 2, which is designed to transmit drive power and, if applicable, assistance power to the rear wheel 11 via the transmission element 12. The drive power can be generated by a rider at a bottom bracket axle 21 by applying rider torque at a specific cadence. This enables muscle-powered propulsion of the electric bicycle 1. In this case, the rider can generate the rider torque via crank arms K with pedals P at the bottom bracket axle 21. The drive system 2 is designed to generate the assistance power at the bottom bracket axle 21, optionally as an alternative or in addition to the drive power.

[0093] Figure 2 shows a schematic diagram of a drive system 2. The drive system 2 is designed to provide, firstly, the drive power for muscle-powered propulsion of the electric bicycle 1 to one wheel, for example, the rear wheel 11. The bottom bracket axle 21 is provided for generating the drive power. Secondly, the drive system is designed to provide, in addition to the drive power at the bottom bracket axle 21, externally generated assistance power by a drive motor 23. The drive power and the assistance power are transmitted from the bottom bracket axle 21 to a wheel 11. A gear ratio for the transmission can be adjusted by means of a gear shift 4.

[0094] 2024 049 EM BRG192 Page 16

[0095] An electronic control unit 22 is designed and configured to control the provision of the assistance power. The electronic control unit 22 includes a motor control unit 221 for this purpose. The motor control unit allows the drive motor 23 to be controlled, for example, by specifying at least one operating parameter. Such an operating parameter could be, for example, a motor current I, a motor torque, a motor speed, a motor power, or an assistance factor. The assistance factor allows the assistance power to be determined by the drive motor 23 based on a multiple of the drive power provided by the rider.

[0096] Furthermore, the electronic control unit 22 includes a motor current unit 223, which serves to detect the motor current I flowing through the drive motor 23. The electronic control unit 22 also includes a speed unit 224, which serves to detect the rotor speed U of a rotor 231 of the drive motor 23. The rotor 231 is rotatably mounted relative to a stator 232 of the drive motor 23 about a rotational axis R. The motor current I and / or the rotor speed U can be detected over time. The electronic control unit 22 includes a storage unit 225, which stores the detected values ​​of the motor current I and / or the rotor speed U. The detected motor current I and the detected rotor speed U can be used by the motor control unit 221 to determine at least one operating parameter.For example, by specifying the motor speed, a target value can be set, and by subsequently recording the rotor speed U, an actual value of the motor speed can be determined, so that a control loop for the rotor speed U can be formed based on this.

[0097] With a slip detection unit 222, the electronic control unit 22 can determine whether a slip situation exists based on the rotor speed U (and / or the motor current I). This determination can be made, for example, by a processor unit 226 of the electronic control unit 22. In a slip situation, the rotor speed U can increase relatively quickly. Values ​​of, for example, 12,000 revolutions per second squared can be reached. Therefore, the increase in the rotor speed U is suitable for determining whether a slip situation exists.

[0098] The drive system 2 also has a frequency unit 24, with which a rider's pedaling frequency, via which the drive power can be determined, is determined.

[0099] 2024 049 EM BRG192 Page 17

[0100] The frequency unit 24 can, for example, include a magnetic sensor that determines the number of revolutions per second of the bottom bracket axle 21 (or a part thereof). The drive system 2 also includes a torque unit 25 that determines the rider torque D. The torque unit 25 can include at least one torque sensor. Motor control by the electronic control unit 22 can be based on the rider's cadence and / or the rider torque D. Slip detection can also be based on the rider's cadence and / or the rider torque D. Another parameter that can be considered by the slip detection unit 222 is the state of the gear shift 4. This state can be determined, in particular, by a speed unit 5 (e.g.,The speed of the electric bicycle 1 determined by a GPS module and the rotor speed U determined by the rotational speed unit 224 can be estimated.

[0101] If the electronic control unit 22 determines that a slippage situation exists, the motor control can be adjusted accordingly. The user can determine the adjustment of the motor control via an input device 3. This determination can, for example, be made by selecting at least one option for the level of assistance. The at least one option for the level can consist of the rider being able to select from one or more factors used to calculate the level of assistance.

[0102] The input device 3 can, for example, be an electronic device (possibly with a touchscreen) suitable for mounting on the electric bicycle 1. Alternatively, the input device 3 can be a mobile device such as a smartphone, configured and designed to communicate (wirelessly) with the electronic control unit to specify at least one option. A software module, for example in the form of an app, can be provided on the mobile device for selecting and transmitting the at least one option to the electronic control unit 22.

[0103] Figure 3 shows an example of a motor current I, a driver torque D, and a rotor speed U over time. Such curves can, for example, be recorded by the electronic control unit 22 and stored in the memory unit 225 of the electronic control unit 2.

[0104] The rider torque D exhibits several periodically occurring maxima, each corresponding to half a pedal crank revolution. The rider torque D is measured in

[0105] 2024 049 EM BRG192 Page 18 shows that the maximum torque K is reached when the crank arms are in a horizontal position and the minimum when they are in a vertical position, resulting in the curve shown (provided the rider pedals continuously). After reaching the most recent maximum, the rider torque shows a steep drop, which results from slippage. The rate of decrease of the rider torque D is in the range of over 200 Nm / s, particularly over 550 Nm / s (on a time scale between 70 ms and 150 ms).

[0106] At the same time, marked by a dashed line running through all graphs, the rotor speed U increases because the drive motor 23 is under less load and therefore rotates faster. In addition, the motor current I (actual curve) decreases. Thus, an analysis of the curves of the motor current I and the rotor speed U, especially in combination, can reliably determine whether a slippage situation exists.

[0107] In the case of motor current I, the determination can include an evaluation of any deviation of the actual curve from the target curve. The control of the target curve can be torque-controlled with a time delay, so that it does not immediately take effect (and reduce the motor current I) when the driver torque D drops sharply. Thus, the deviation can be evaluated by assessing the difference between the actual and target curves. In this case, the difference at the time of the minimum of the actual curve is 80% of the value of the target curve.

[0108] Additionally or alternatively, it can be determined whether the motor current I (of the target curve) exceeds a predefined threshold value Is. The threshold value Is can, for example, be between 1 A and 10 A. This assumes that at a lower motor current I, no slippage can occur because the drive power and / or the support power are too low. Even if the rotor speed U increases, which would indicate a slippage situation, it can then be determined that no slippage is present.

[0109] In the case of rotor speed U, the determination is made as a function of an increase in rotor speed U. For this purpose, the increase can be determined in a first, a second, and a third time window Z1, Z2, Z3. The use of two or more time windows is generally conceivable and possible. In the first time window Z1, no significant increase in rotor speed U is determined. The increase is below a threshold value. The electronic control unit 22 can, for example, determine that a further measurement is not required immediately afterward. The second

[0110] 2024 049 EM BRG192 Page 19

[0111] Time window Z2 therefore has a relatively large time interval from the first time window Z1 and is itself longer than the first time window Z1. In the second time window Z2, the increase exceeds a threshold value. In the next step, it is verified that the increase measured in the second time window Z2 is continuous. The third time window Z3 therefore has a relatively small time interval from the second time window Z2 and is itself shorter than the second time window Z2. This allows for a quick second measurement result and simultaneously increases the measurement accuracy for the increase in rotor speed U across the two time windows Z2 and Z3. In the third time window Z3, the increase also exceeds a threshold value, from which the electronic control unit 22 determines that a slippage situation exists. In principle, alternative intervals and lengths for time windows Z1, Z2, and Z3 are conceivable and possible.

[0112] Within the second time window Z2, there is a relatively short, steep increase and decrease in rotor speed II. The electronic control unit 22 is designed and configured to detect such features of the rotor speed U curve and to determine whether this is due to play in the drive system 2. For this purpose, the feature is examined within a time-limited period tp. By limiting the period tp, it can be ruled out that increases and decreases in rotor speed U relevant for slip detection are interpreted as play in the drive system 2. In this case, the feature could, for example, be caused by play in a transmission element 12 between the drive system 2 and a wheel of the electric bicycle 1, thus briefly resulting in a higher rotor speed U.If the electronic control unit 22 determines that the rise and fall is due to play in the drive system 2, the presence of a slip situation is not (unintentionally) determined on this basis.

[0113] Figure 4 shows further exemplary waveforms of motor current I, rider torque D, and rotor speed U over time. These waveforms represent standard signal waveforms during clutch engagement, section by section. The starting point is a situation in which the rider is not turning the pedals K, and therefore no rider torque D is applied. The motor current I and the rotor speed U are thus zero. From this point, the pedals K are turned. This increases the rider torque D. As a reaction, the rotor speed II increases. This increase is similarly steep to that in a slipping situation, so that a corresponding threshold value can be exceeded in at least one time window. Therefore, it can be advantageous for the electronic control unit to be designed and configured to recognize a standard signal waveform like this. This recognition can be achieved, for example, by...

[0114] 2024 049 EM BRG192 Page 20

[0115] The determination is based on one or more of the following three criteria: The rotor speed U was zero before the increase. The motor current I was zero before the increase. The motor current I is below a threshold value Is (here: below 5 A). If the electronic control unit detects such a standard signal pattern, it can temporarily interrupt the determination of whether a slip situation exists. The length of the interruption can vary depending on the

[0116] Adjust the length of the standard signal waveform. The standard signal waveform shown ends, for example, after the second increase in rotor speed U when the engagement is complete (e.g., after less than 250 ms).

[0117] 2024 049 EM BRG192 Page 21

[0118] Reference symbol list

[0119] 1 electric bicycle

[0120] 10 front wheel

[0121] 11 Rear wheel

[0122] 12 Transfer element

[0123] 2 Drive system

[0124] 21 Bottom bracket axle

[0125] 22 electronic control unit

[0126] 221 Engine control unit

[0127] 222 Slip detection unit

[0128] 223 Motor current unit

[0129] 224 speed unit

[0130] 225 storage unit

[0131] 226 processor unit

[0132] 23 Drive motor

[0133] 231 Rotor

[0134] 232 Stator

[0135] 24 frequency unit

[0136] 25 torque unit

[0137] 3 Input device

[0138] 4-speed gearbox

[0139] 5 speed unit

[0140] Driver torque

[0141] I Motor current

[0142] Is threshold

[0143] KT retkurbel

[0144] P Pedal

[0145] R axis of rotation tp playing time

[0146] U Rotor speed

[0147] Z1, Z2, Z3 Time window

[0148] 2024 049 EM

Claims

BRG192 Page 22 Claims 1. Drive system (2) for an electric bicycle (1), with - a bottom bracket shaft (21) for generating drive power for muscle-powered propulsion of the electric bicycle (1), - at least one drive motor (23) for providing externally driven support power in addition to the drive power at the bottom bracket shaft (21), wherein the at least one drive motor (23) has a rotor (231), and - an electronic control unit designed and configured to control the provision of the support service, characterized in that the electronic control unit (22) is designed and configured to, - to record a rotor speed (U) over time, - to determine an increase in rotor speed (U) in at least one first and second time window (Z1 , Z2, Z3) and - to determine, depending on the increase in rotor speed (U), whether a slip situation exists and / or what the intensity of the slip is.

2. Drive system (2) according to claim 1 , characterized in that the at least one first and second time window (Z1 , Z2, Z3) have different lengths.

3. Drive system (2) according to one of claims 1 and 2, characterized in that the electronic control unit (22) is provided and configured to determine that a slip situation exists when the increase in rotor speed (U) exceeds a limit threshold value in at least one of the time windows (Z1 , Z2, Z3), wherein the limit threshold value is adaptable depending on a state of a gear shift (4) of the drive system (2) estimated by the electronic control unit (22).

4. Drive system (2) according to one of claims 1 to 3, characterized in that the electronic control unit (22) is provided and configured to determine whether a slip situation exists depending on whether a motor current (I), with which the at least one drive motor (23) is used to generate the 2024 049 EM BRG192 Page 23 The support power is available, is above a specified threshold (Is), and / or whether an actual motor current profile deviates from a target motor current profile.

5. Drive system (2) according to one of the preceding claims, characterized in that the electronic control unit (22) is provided and configured to detect whether an increase in rotor speed (U) is due to play in the drive system (2).

6. Drive system (2) for an electric bicycle (1), with - a bottom bracket shaft (21) for generating drive power for muscle-powered propulsion of the electric bicycle (1), - at least one drive motor (23) for providing externally driven support power in addition to the drive power at the bottom bracket shaft (21), and - an electronic control unit (22) which is designed and configured to control the provision of the support service and to detect the existence of a slippage situation, characterized in that the electronic control unit (22) is designed and configured to - to provide a support service for a specified support period after the end of the slippage situation, which has at least a specified support value, and / or that the electronic control unit (22) is designed and configured for this purpose, - to provide the support power in a first operating mode via control of a motor torque and in a second operating mode via control of a motor speed and - to select the second operating mode after recognizing that a slippage situation exists, and / or that the electronic control unit (22) is designed and configured to do so, - to provide at least one option for a level of assistance that can be selected by the driver, and 2024 049 EM BRG192 page 24 after recognizing that a loophole situation exists, to adjust the support service according to at least one option.

7. Drive system (2) according to claim 6, characterized in that the electronic control unit (22) is provided and configured to maintain the second operating mode at least for a predetermined switching period.

8. Drive system (2) according to one of claims 6 or 7, characterized in that the electronic control unit (22) is provided and configured to specify, at least initially, a motor speed after the selection of the second operating mode, which is based on a motor speed before the detection of the presence of a slip situation.

9. Drive system (2) according to claim 8, characterized in that the electronic control unit (22) is provided and configured to specify the motor speed for a predetermined transition period.

10. Drive system (2) according to one of claims 6 to 9, characterized in that the electronic control unit (22) is provided and configured to classify an intensity of slip into at least two categories and - to select the second operating mode additionally based on the classification and / or - to further adjust the support service based on the classification.

11. Drive system (2) for an electric bicycle (1), with - a bottom bracket shaft (21) for generating drive power for muscle-powered propulsion of the electric bicycle (1), - at least one drive motor (23) for providing externally driven support power in addition to the drive power at the bottom bracket shaft (21), wherein the at least one drive motor (23) has a rotor (231), and - an electronic control unit (22) designed and configured to control the provision of the support service and a 2024 049 EM BRG192 Page 25 comprising a speed unit (224) which serves to detect a rotor speed (II) of the rotor (231), characterized in that the electronic control unit (22) is provided and configured to control the support power in such a way that an increase in the rotor speed (U) does not exceed a maximum value.

12. Drive system (2) according to claim 11, characterized by a gear shift (4) with which a variable transmission ratio in the form of different gears is provided for the transmission of the drive power and / or the support power from the bottom bracket shaft (21) to a driven wheel, wherein the electronic control unit (22) is provided and configured to specify the maximum value depending on the gear.

13. Drive system (2) according to claim 11, characterized by an input device (3) for recording an input of the maximum value, wherein the electronic control unit (22) is provided and configured to specify the maximum value depending on the input.

14. Procedure for determining whether a slippage situation exists in an electric bicycle (1), comprising the following steps: - Generating drive power for muscle-powered propulsion of the electric bicycle (1) at a bottom bracket axle (21) of the electric bicycle (1), - Providing an externally powered support power in addition to the drive power at the bottom bracket shaft (21) by at least one drive motor (23), - Determining the rotor speed (U) of a rotor (231) of the at least one drive motor (23), - Determining an increase in rotor speed (U) in at least one first and second time window (Z1 , Z2, Z3) and - Determine whether a slip situation exists, depending on the increase in rotor speed (U). 2024 049 EM BRG192 Page 26 15. Method for operating a drive system (2) for an electric bicycle (1) after detecting a slip situation, comprising the following steps: - Generating drive power for muscle-powered propulsion of the electric bicycle (1) at a bottom bracket axle (21) of the electric bicycle (1), - Providing an externally driven support power in addition to the drive power at the bottom bracket axle (21) by at least one drive motor (23), characterized in that, after the end of the slip situation, a support power is provided for a predetermined support period, which has at least one predetermined support value, and / or that the support power is provided in a first operating mode via control of a motor torque and in a second operating mode via control of a motor speed, wherein, after the detection of a slip situation, the second operating mode is selected, and / or that at least one option for a level of support power is provided, which can be selected by the rider, wherein, after the detection of a slip situation,The support level will be adjusted according to at least one option.

16. Computer program product comprising instructions which, when executed by at least one processor of an electronic control unit (22) for a drive system (2) of an electric bicycle (1), cause the at least one processor to execute a method according to claim 14 or 15.

17. Electric bicycle (1) with a drive system (2) according to one of claims 1 to 13. 2024 049 EM

Images