Method for controlling a drive train, drive train and vehicle

Abstract

A method for controlling a drive train (4) of a vehicle (2) is described, wherein the drive train (4) has at least one shaft (6) which is accelerated when the vehicle (2) is driven by a driver, wherein the drive train (4) has a drive motor (12) for providing drive force to assist the driver of the vehicle (2) in driving the vehicle (2). The method comprises determining (S1) an angular acceleration of the shaft (6) and controlling (S2) the drive motor (12), wherein the assistance by the drive motor (12) is switched on or off depending on the determined angular acceleration. Furthermore, a drive train (4) for a vehicle (2) and a vehicle (2) having such a drive train (4) are described.

Description

[0001] The present invention relates to a method for controlling a drive train of a vehicle. Furthermore, the present invention relates to a drive train for a vehicle and to a vehicle having such a drive train, wherein the vehicle can be operated at least temporarily using muscle power.

[0002] Vehicles that can be operated at least temporarily using muscle power, such as a bicycle, e-bike, pedelec, or cargo bike, can also have a drive motor to assist in propelling the vehicle. For example, a pedelec, as a muscle-powered vehicle, can have an electric motor to assist in propulsion. The assistance provided by the drive motor must be controlled. For safety reasons, for example, assistance may only be provided when a driver of the vehicle is pedaling. To determine whether the driver is pedaling, a driver torque can be measured. The driver torque is a torque that the driver of the vehicle applies to a pedal crankshaft of the vehicle to drive the vehicle using muscle power. Methods and systems that control the drive motor depending on the driver torque are known from the prior art.

[0003] For example, DE 10 2022 132 256 A1 describes how driver torque is detected with a sensor, and the drive motor is controlled based on this. Such a sensor for detecting driver torque increases the system complexity of the vehicle. Furthermore, such a sensor can fail or detect an incorrect driver torque value.

[0004] The object of the invention, based on the prior art, is to improve the control of the drive motor of a vehicle that is at least temporarily powered by human power. This object is achieved by the subject matter having the features of the independent claims. Advantageous further developments are set out in the subclaims.

[0005] In a first aspect, the invention relates to a method for controlling a drive train of a vehicle. The vehicle can be, for example, a bicycle, e-bike, pedelec, or cargo bike. The method for controlling the drive train can be a method for controlling a drive motor, such as an electric motor of the drive train. Steps of the method can be carried out, for example, using a control device of the vehicle.

[0006] The drive train has a shaft which is accelerated when the vehicle is driven by a driver. The shaft can be a pedal crankshaft of the vehicle. Crank arms can be connected to the pedal crankshaft in a rotationally fixed manner. For example, two crank arms can be connected to the pedal crankshaft in a rotationally fixed manner, with a pedal being rotatably mounted at one end of each crank arm. The pedal crankshaft can therefore also be referred to as a pedal crankshaft. The pedal crankshaft is rotatably mounted on a vehicle frame by means of a bearing. The bearing can be a rolling bearing, for example a ball bearing, a needle bearing or a roller bearing. The pedal crankshaft can absorb the driving force of a driver of the vehicle to drive the vehicle.

[0007] The shaft can be directly connected to the crankshaft. The shaft can be at least indirectly connected to the crankshaft, for example, via a gear. The shaft can be mechanically connected to the crankshaft. When the rider drives the vehicle, the shaft can be accelerated along with the crankshaft using muscle power. An acceleration of the shaft, such as an angular acceleration or rotational acceleration, can be directly correlated to an acceleration of the crankshaft; for example, the accelerations can be linear to one another. For example, the acceleration of the shaft can be identical to the acceleration of the crankshaft.

[0008] The drive train has a drive motor for providing drive power to assist the driver of the vehicle in propelling the vehicle. The drive motor can be an electric motor. The drive motor can be used to relieve the driver's workload while driving and, alternatively or additionally, to increase the vehicle's range. The drive motor can be configured to provide drive power to relieve the driver's workload. For example, drive power provided by the driver through muscle power applied to the pedals and the crankshaft can be used, and drive power provided by the drive motor can be used to propel the vehicle. The drive power provided by the drive motor can relieve the driver's workload.

[0009] The method includes determining an angular acceleration of the shaft. A temporal profile of the angular acceleration can be determined, for example, for time-equidistant values ​​of the angular acceleration. For example, a time-discrete function can be determined as the angular acceleration. An angular acceleration of the pedal crankshaft can be determined. The angular acceleration can be determined directly or indirectly. The angular acceleration can be determined directly using a sensor. Alternatively or additionally, the angular acceleration can be determined indirectly and as a function of another measured variable.

[0010] The method further comprises controlling the drive motor, wherein the assistance provided by the drive motor is switched on and alternatively or additionally switched off depending on the determined angular acceleration. For example, a first value of the angular acceleration can be determined at a first point in time, and the control of the drive motor can be carried out such that the assistance is switched on depending on this first angular acceleration. The first angular acceleration can correspond to a value which indicates that the driver is pedaling. When the assistance is switched on, drive power is provided by the drive motor to drive the vehicle, for example, and is transferred to a driven wheel of the vehicle to drive the vehicle.

[0011] For example, a second angular acceleration can be determined at a second point in time later than the first. This second angular acceleration can differ from the first angular acceleration in terms of sign and, alternatively or additionally, in magnitude. The second angular acceleration can correspond to a value which suggests that the driver is not pedaling and, for example, is merely placing their feet on the pedals. For example, a sign of the second angular acceleration can be different from the sign of the first angular acceleration. The drive motor can be controlled in such a way that the assistance provided by the drive motor is switched off depending on this second angular acceleration. If the assistance is switched off, for example, no driving force is provided by the drive motor to drive the vehicle.

[0012] With such a method, it is particularly easy to detect when the rider is pedaling and to switch the assistance from the drive motor on or off depending on this. Pedaling can be determined by determining the angular acceleration of the shaft, whereby the shaft is at least indirectly connected to the pedal crankshaft which is directly accelerated by the rider when pedaling. For example, as described in the example above, the first value of the angular acceleration is determined and thus it is detected, for example, that the rider is pedaling. If the second value of the angular acceleration is determined, for example a value with the opposite sign to the first value of the angular acceleration, it is determined, for example, that the rider is not pedaling. The drive motor and, alternatively or additionally, the assistance provided by it are then switched off.

[0013] According to the law of conservation of angular momentum, there is a relationship between the sum of all torques acting on a shaft, the shaft's moment of inertia, and the shaft's angular acceleration. Thus, the sum of the acting torques is equal to the shaft's moment of inertia multiplied by the shaft's angular acceleration. The angular acceleration of the shaft, and thus of the pedal crankshaft indirectly accelerated by the shaft, therefore correlates positively with the driver's torque applied to the shaft, for example, the pedal crankshaft. The driver's torque can be a torque applied by the driver to propel the vehicle. The shaft's moment of inertia can be predetermined and stored as a hard-coded value on the control device. By determining the angular acceleration, the driver's torque can be deduced.The control can therefore be carried out in at least indirect dependence on the driver torque, without the driver torque having to be measured directly.

[0014] Switching off the drive motor's assistance when the rider is not pedaling may be necessary to increase the safety of such vehicles. Compared to conventional methods, in which the rider torque applied to the pedal crankshaft is measured and determined using a torque sensor, this method makes it particularly easy to detect the rider's pedaling. This is done by determining the angular acceleration. Determining the rider torque with a special torque sensor is normally comparatively complex due to the rotating parts on the pedal crankshaft. Furthermore, the necessary installation space for such a torque sensor is required, which can increase development and production costs as well as system complexity.Likewise, with such an additional sensor on the vehicle, the number of electrical and electronic interfaces must be increased to connect the sensor to the vehicle's existing power supply and to communicate with other electronic units in the vehicle. Furthermore, such a sensor, like any component, can be faulty or fail. This can reduce the reliability, availability, and safety of the vehicle. The method described here can reduce the number of required sensors and electrical and electronic interfaces. Often, a sensor for measuring another parameter is already present, and the angular acceleration can be determined based on it.

[0015] Some vehicles that are at least temporarily human-powered have a freewheel between the pedal crankshaft and the driven wheel. The freewheel can be open or closed. When the freewheel is closed, drive power applied to the pedal crankshaft can be transferred to the driven wheel to drive the vehicle. When the freewheel is open, for example, no drive power is transferred from the pedal crankshaft to the driven wheel to drive the vehicle. If no drive power is transferred, for example, no rider torque is applied to the pedal crankshaft because there is no resistance on the pedal crankshaft when pedaling. If the vehicle is already moving before the rider starts pedaling, for example, the freewheel is open.When the rider begins pedaling, for example, the freewheel is still open, and at the same time the crankshaft exhibits a certain angular acceleration that is not equal to zero. After a certain rotation of the crankshaft through a certain angle, the freewheel is closed. Drive power is then transferred and a rider torque that is not equal to zero is applied to the crankshaft. Accordingly, for example, the angular acceleration of the shaft is not equal to zero at a certain point in time, while at the same time no rider torque is applied. Thus, the method can be used to determine earlier in time whether the rider is pedaling or not, compared to conventional methods and depending on the rider torque.Accordingly, the method represents a possibility to switch the support of the drive motor on or off depending on the pedaling by the driver and at the same time the detection time of the pedaling can be reduced, which can, for example, improve comfort and safety.

[0016] Detection accuracy can also be improved by eliminating the need to wait for the rider to apply torque. Safety can be improved by allowing the rider to rely on the drive motor's activation or deactivation of assistance depending on pedaling. Furthermore, determining angular acceleration is usually less complex than determining the torque at the crankshaft, for example, because fewer additional sensors are required on the vehicle.

[0017] According to a further embodiment, the method can be characterized in that, during control, the assistance can be activated by the drive motor when the determined angular acceleration exceeds a first threshold. The activation of the assistance can involve the provision of drive force by the drive motor. The first threshold can be defined, for example, such that the angular acceleration is greater than the first threshold when the rider begins pedaling. For example, the rider can begin pedaling, and thus the angular acceleration can exceed the first threshold.

[0018] Thus, depending on the first threshold value, which can be stored, for example, as a hard-coded value on the vehicle's control device, a limit value for activating assistance by the drive motor can be objectively defined. This allows the time at which pedaling begins to be detected. Thus, the method can implement event detection regarding the start of pedaling by determining the angular acceleration.

[0019] According to a further embodiment, the method can be characterized in that, during control, the assistance provided by the drive motor can be switched off if the determined angular acceleration falls below a second threshold. Switching off the assistance can involve terminating the provision of the drive force by the drive motor. The second threshold can be the same as or different from the first threshold. The first and second thresholds can be different. For example, the first and second thresholds can have different signs. The magnitude of the first threshold can be the same as or different from the magnitude of the second threshold.

[0020] This allows the point in time at which pedaling stops to be detected. Thus, the method can be used to implement event detection regarding the end of pedaling by determining the angular acceleration.

[0021] For example, the angular acceleration may be positive at a first point in time and exceed the first threshold, which may be positive. This can be used to determine that the driver is pedaling at the first point in time and is using muscle power to propel the vehicle. For example, the driver may start pedaling, and the angular velocity of the shaft may increase. This can be used to determine that the angular acceleration is positive at the first point in time. At a later, second point in time, the driver may stop pedaling, and the angular acceleration may be negative. This angular acceleration may fall below the second threshold, which may be negative. This can be used to determine, for example, that the driver is no longer pedaling.

[0022] For example, a hysteresis effect can be provided by the method if the values ​​of the first and second threshold values ​​are different. For example, the value of the first threshold value can be greater than the value of the second threshold value. If, for example, the value of the first threshold value is greater than the value of the second threshold value, the assistance can only be switched on at a larger value of the angular acceleration, whereas the assistance can be switched off at a smaller value of the angular acceleration. This can ensure, for example, that the assistance is only switched on when the rider generates a certain minimum acceleration of the shaft by applying muscle power to the pedals and crankshaft, and the angular acceleration thus exceeds this first threshold value.At the same time, the smaller value of the second threshold ensures that the rider has to stop pedaling more quickly than they started pedaling. The assistance can then be switched off. This allows the drive motor to switch off assistance in a defined manner via the second threshold.

[0023] According to a further embodiment, the method can be characterized in that a further measured variable can be determined on the drive train. As a further measured variable, for example, a rotational speed of a wheel or a longitudinal acceleration of the vehicle can be determined. For example, the measured variable can be measured, for example with a sensor. Alternatively or additionally, the measured variable can be determined approximately, for example with an approximation method depending on a further measured variable. The drive motor can be controlled depending on the determined further measured variable. In this case, the drive motor can be controlled depending on the determined further measured variable and additionally depending on the determined angular acceleration.Thus, the support by the drive motor can be switched on or off depending on the specific angular acceleration as well as depending on the specific other measured value.

[0024] This can, for example, further improve accuracy. Alternatively or additionally, the process can be made more fail-safe by implementing redundancy. This can reduce the vehicle's reliability, availability, and safety.

[0025] According to a further embodiment, when determining the further measured variable, a torque on the shaft can be measured using a torque sensor. This allows the further measured variable to be determined. The torque sensor can have one or more strain gauges. The shaft can be the pedal crankshaft. The torque on the pedal crankshaft can be a rider torque. The drive motor can be controlled depending on the measured torque. Control of the drive motor and thus, for example, switching the assistance provided by the drive motor on or off can be carried out both depending on the determined angular acceleration and depending on the measured torque.

[0026] This allows redundancy to be implemented through the method when controlling the drive motor and when providing assistance by the drive motor by switching it on or off. This improves the safety, availability, and reliability of the method and therefore of the vehicle. This can be advantageous for safety-critical functions, such as switching the assistance of the drive motor on or off. Such a method can also reduce the time delay that occurs before the freewheel is closed in conventional methods, which only have a torque sensor to measure the driver torque and switch the assistance of the drive motor on or off depending on this. With the method presented here, for example, the switching on or off can initially be carried out solely as a function of the determined angular acceleration.Within a specific time window, this control of the assistance and the control of the drive motor can then be checked based on the measured torque. This allows the measured rider torque to be used to control the drive motor to engage or disengage the drive motor's assistance, whereby the time delay when starting pedaling and before the freewheel engages can be reduced using the determined angular acceleration.

[0027] According to a further embodiment, the drive motor can be controlled depending on the determined angular acceleration when a measuring range of the torque sensor is exceeded. For example, the drive motor can be controlled depending on the determined angular acceleration, for example when, only when, or precisely when the measuring range of the torque sensor is exceeded. The measuring range can be a predefined range of the torque sensor, within which the torque sensor can measure the torque on the shaft with a predefined high confidence level. During control, the activation or deactivation of the assistance can be carried out depending on the determined angular acceleration when a measuring range of the torque sensor is exceeded.

[0028] This makes it possible, for example, to use the torque sensor to determine the driver torque and to control the drive motor based on the measured driver torque, provided the measuring range is not exceeded. If the measuring range is not exceeded, the torque can be measured with a high level of confidence. If the measuring range is exceeded, the torque can no longer be measured with a high level of confidence. The determined angular acceleration can then be used to control the drive motor instead. This makes it possible to control the drive motor outside the measuring range of the torque sensor, even though the torque sensor itself cannot measure the torque with a high level of confidence. This allows a simple torque sensor to be installed which enables the torque to be measured within a specific measuring range.At the same time, larger torques are possible, such as greater rider torque on the crankshaft, which do not need to be measured directly for control. Instead, the angular acceleration can be determined, which at least correlates with the torque. This allows control to be performed even outside the measurement range.

[0029] According to one embodiment, a determination can be made as to whether a fault condition of the torque sensor exists, for example at least one fault condition. A fault condition can comprise a failure or failure condition of the torque sensor. The determination as to whether a fault condition exists can be made using a means. The means can be the control device for carrying out steps of the method. Alternatively or additionally, the means can be the torque sensor itself. The control of the drive motor can be carried out as a function of the determined angular acceleration, for example when, only when, or precisely when a fault condition exists, for example at least one fault condition. During control, the activation or deactivation of the assistance can be carried out as a function of the determined angular acceleration when a fault condition exists, for example at least one fault condition.

[0030] This makes it possible to ensure that control is performed depending on the determined angular acceleration when the torque sensor is in a faulty state, for example, if the torque sensor has failed. This can increase the reliability of controlling the drive motor by using the determined angular acceleration instead of the torque measured by the torque sensor to control the drive motor. This can increase the safety, reliability, and availability of such a vehicle.

[0031] A second aspect of the present invention relates to a drive train for a vehicle. The vehicle can be a bicycle, e-bike, pedelec, or cargo bike that is operated at least temporarily by muscle power. The drive train can have a shaft that is accelerated when the vehicle is driven by a rider. For example, the shaft can be mechanically operatively connected to the pedal crankshaft. For example, the shaft can be the pedal crankshaft. Crank arms can be connected to the pedal crankshaft in a rotationally fixed manner. For example, two crank arms can be connected to the pedal crankshaft in a rotationally fixed manner, wherein a pedal can be rotatably mounted at one end of each crank arm. The pedal crankshaft can therefore also be referred to as a pedal crankshaft. The pedal crankshaft can be rotatably mounted on a frame of the vehicle by means of a bearing of the vehicle.The bearing can be a rolling bearing, such as a ball bearing, a needle bearing, or a roller bearing. The pedal crankshaft can be used to capture the driving force of a vehicle's driver to propel the vehicle.

[0032] Furthermore, the drive train can include a drive motor, such as an electric motor, for providing drive power to assist a driver of the vehicle in driving the vehicle. The drive motor can be configured to reduce the driver's workload while driving and to increase the range. Furthermore, the drive motor can be configured to provide drive power to reduce the driver's workload.

[0033] The drive train may include a means for determining an angular acceleration of the shaft. The drive train may include one or more means for determining the angular acceleration. Furthermore, the drive train may include a control device for controlling the drive motor. The assistance provided by the drive motor can be activated and deactivated alternatively or additionally depending on the determined angular acceleration.

[0034] Thus, the drive train can be configured to engage or disengage the load relief or assistance provided by the drive motor depending on the angular acceleration of the shaft. Further features, embodiments, and advantages can be found in the descriptions of the first aspect. Conversely, features, embodiments, and advantages of the second aspect also represent features, embodiments, and advantages of the first aspect.

[0035] According to a further embodiment, the drive train can be characterized in that the control device can be configured to carry out steps of a method according to an embodiment of the first aspect of the present invention. The drive train can be configured to carry out all steps of the method according to an embodiment of the first aspect. For example, the means for determining the acceleration and the control device can jointly be configured to carry out all steps of the method according to an embodiment of the first aspect. Furthermore, the drive train can have a torque sensor for measuring a torque on the shaft.

[0036] According to a further embodiment, the drive train can be characterized in that the drive train can have a sensor for measuring an angle signal of the shaft. The angle signal can be measured as a time profile, for example, with angle values ​​with time-equidistant intervals between the individual angle values. The sensor can be configured to measure a crank angle of the crank arms of the pedal crankshaft. The control device can be configured as the means for determining the angular acceleration as a function of the measured angle signal. The angular acceleration can be determined by approximately twice the time differentiation of the angle signal. Thus, the crank angle can be measured using a sensor for measuring the crank angle, which is often already present in conventional vehicles. The angular acceleration can be determined as a function of this.For example, a dedicated angular acceleration sensor is no longer necessary. This can reduce the complexity of the drivetrain and thus increase reliability.

[0037] According to a further embodiment, the drive train can be characterized in that the drive train can have a sensor for measuring a cadence of the shaft. The cadence can be measured as a time profile, for example, with cadence values ​​with time-equidistant intervals between the individual cadence values. The sensor can be configured to measure the cadence of the pedal crankshaft. The cadence can be an angular velocity, for example, a crank angular velocity of the pedal crankshaft. The control device can be configured as the means for determining the angular acceleration as a function of the cadence. The angular acceleration can be determined by approximately simple time differentiation of the cadence. The advantages with respect to the previous embodiment also apply to this embodiment.

[0038] Determining the angular acceleration by means of approximate differentiation can be carried out using a numerical method. The determination can be an approximate determination. A numerical method can, for example, determine the angular acceleration using the difference quotient. A numerical method can, for example, determine the angular acceleration using a differentiating low-pass filter, for example using a differentiating IIR or FIR low-pass filter. For example, the cadence can be simply derived over time as a discrete function of time with time-equidistant intervals between the measured cadence values. For example, the angle signal can be derived twice over time as a discrete function of time with time-equidistant intervals between the measured values ​​of the angle signal. For this purpose, the difference quotient can, for example, be determined twice.Alternatively, the differential low-pass filter can be applied twice. For this purpose, the low-pass filter can be a singly differential low-pass filter. Alternatively, a doubly differential low-pass filter, such as an IIR or FIR low-pass filter, can be applied. This doubly differential low-pass filter, for example, is applied once.

[0039] A third aspect of the present invention relates to a vehicle with a drive train according to an embodiment of the second aspect of the present invention. The vehicle can be a bicycle, e-bike, pedelec, or cargo bike that is powered at least temporarily by muscle power. Further features, embodiments, and advantages can be found in the descriptions of the first aspect and the second aspect, respectively. Conversely, features, embodiments, and advantages of the third aspect also represent features, embodiments, and advantages of the first and second aspects, respectively. Fig. 1 schematically shows steps of a method for controlling a drive train of a vehicle. Fig. 2 shows schematically a vehicle with a drive train and a control device for carrying out the functions shown schematically in Fig. 1 depicted steps of the method for controlling the drive train.

[0040] Fig. 1 schematically shows steps of a method for controlling a drive train 4 of a vehicle 2. Fig. 2 schematically shows such a vehicle 2, which can be operated at least temporarily by muscle power, with such a drive train 4. The drive train 4 has a shaft 6, which is accelerated when the vehicle 2 is driven by a driver of the vehicle 2. According to one embodiment, the shaft 6 is a pedal crankshaft of the vehicle 2. The pedal crankshaft is rotatably mounted on a frame of the vehicle 2 by means of a bearing of the vehicle 2. The pedal crankshaft further has pedals (not shown) which are rotatably arranged on crank arms (not shown) of the pedal crankshaft. The bearing is a rolling bearing. Furthermore, the drive train 4 has a drive motor 12 for providing drive power to assist a driver of the vehicle 2 in driving the vehicle 2.

[0041] Furthermore, the drive train 4 has a sensor 13 for measuring S5 an angle signal of the shaft 6. According to one embodiment, the sensor 13 is configured to measure S5 a crank angle of the pedal crankshaft. The sensor 13 is arranged on the frame of the vehicle 2.

[0042] Furthermore, the drive train 4 has a sensor 14 for measuring S6 a cadence of the shaft 6. According to one embodiment, the sensor 14 is configured to measure S6 the cadence of the pedal crankshaft. The sensor 14 is arranged on the frame of the vehicle 2.

[0043] Furthermore, the drive train 4 has a torque sensor 15 for measuring S3.1 a torque on the shaft 6. The torque sensor 15 is configured to determine S3 a further measured variable on the drive train 4. During the determination S3 of the further measured variable, a measurement S3.1 of a torque on the shaft 6 is carried out using the torque sensor 15. According to one embodiment, the torque sensor 15 is configured to measure S3.1 a rider torque on the pedal crankshaft. This determines the further measured variable. The torque sensor 15 is arranged on the shaft 6. The torque sensor 15 has at least one strain gauge for measuring S3.1 the torque.

[0044] According to one embodiment, the drivetrain 4 comprises both the sensor 13 for measuring the angle signal S5 and the sensor 14 for measuring the cadence S6, as well as the torque sensor 15 for measuring the torque S3.1. In an alternative embodiment, the drivetrain comprises two of the sensors 13, 14 and the torque sensor 15. In an alternative embodiment, the drivetrain 4 comprises either the sensor 13 for measuring the angle signal S5, the sensor 14 for measuring the cadence S6, or the torque sensor 15 for measuring the torque S3.1.

[0045] The drive train 4 further includes a control device 16. The control device 16 is communicatively connected to the sensors 13, 14, the torque sensor 15, and the drive motor 12.

[0046] The drive train 4 further comprises a means for determining S1 of an angular acceleration of the shaft 6. The control device 16 is configured as the means for determining S1 of the angular acceleration. According to one embodiment, the control device 16 is configured to determine S1 of the angular acceleration as a function of the measured angle signal. According to one embodiment, the control device 16 is configured to determine S1 of the angular acceleration as a function of the measured cadence.

[0047] The determination S1 of the angular acceleration is carried out approximately. According to one embodiment, a profile of the angular acceleration is determined from a measured profile of the angle signal using a numerical method. According to one embodiment, a profile of the angular acceleration is determined from a measured profile of the cadence using a numerical method. The numerical method is a method for temporal differentiation. In this case, a single or double temporal differentiation is carried out by the control device 16. According to one embodiment, a single differentiation of the cadence is carried out in order to determine the angular acceleration. According to one embodiment, a double differentiation of the angle signal is carried out in order to determine the angular acceleration. According to one embodiment, both the single and the double differentiation are carried out.This increases the accuracy of determining S1 of the angular acceleration. According to one embodiment, either single or double differentiation is performed. This reduces the computational effort required to determine S1 of the angular acceleration.

[0048] The control device 16 is configured to control S2 the drive motor 12. The support by the drive motor 12 is switched on or off depending on the determined angular acceleration. The control device 16, the sensors 13, 14 and the torque sensor 15 are configured to carry out steps of the process schematically shown in Fig. 1 shown procedure.

[0049] During control S2, the assistance provided by the drive motor 12 is switched on (S2.1) when the determined angular acceleration exceeds a first threshold. Furthermore, during control S2, the assistance provided by the drive motor 12 is switched off (S2.2) when the determined angular acceleration falls below a second threshold. In the embodiment shown, the magnitude of the first threshold is greater than the magnitude of the second threshold. The first threshold has a positive sign, and the second threshold has a negative sign. In an alternative embodiment, the magnitude of the first and second thresholds are identical.

[0050] Furthermore, the control S2 of the drive motor 12 is carried out as a function of the determined further measured variable. The control S2 of the drive motor 12 is carried out as a function of the determined torque, which was determined using the torque sensor 15. This implements redundancy through the method. The control S2 of the drive motor 12 as a function of the angular acceleration is checked using the determined torque. In an alternative embodiment, the control S2 of the drive motor 12 is carried out as a function of the determined torque, and the control S2 of the drive motor 12 as a function of the determined angular acceleration implements the redundancy in the control S2.

[0051] Thus, according to one embodiment, the control S2 of the drive motor 12 is carried out as a function of the determined angular acceleration when a measuring range of the torque sensor 15 is exceeded. The measuring range defines a range in which the measured torque values ​​have a high confidence level. Outside the measuring range, the measured torque values ​​have a lower confidence level. Thus, according to one embodiment, the control S2 is carried out as a function of the torque measured with the torque sensor 15 and independently of the angular acceleration when the measuring range is not exceeded. If the measured torque is outside the measuring range and thus the measuring range is exceeded, the control S2 of the drive motor 12 is carried out as a function of the determined angular acceleration and independently of the measured torque.

[0052] According to one embodiment, a determination S4 is performed to determine whether a fault condition exists in the torque sensor 15. According to one embodiment, the determination S4 is performed by the control device 16. Thus, the determination S4 is performed by an element other than the torque sensor 15. This reduces the susceptibility to errors. According to one embodiment, the determination S4 is performed with the torque sensor 15. This reduces the demand on the control device 16. According to one embodiment, a determination S4 is performed by both the control device 16 and the torque sensor 15. According to one embodiment, a determination S4 is performed either by the control device 16 or by the torque sensor 15. An error condition includes both a simple error in the torque sensor 15, such as incorrect calibration, and a failure of the torque sensor 15.If a fault condition exists, control S2 of the drive motor 12 is performed depending on the determined angular acceleration. According to one embodiment, control S2 is performed depending on the measured torque and independently of the determined angular acceleration if no fault condition exists. If a fault condition exists, control S2 is performed independently of the measured torque and depending on the determined angular acceleration.

[0053] Such a method and such a drive train 4 enable the precise and rapid detection and determination of pedaling by the driver of the vehicle 2. Thus, the method and the drive train 4 are configured to detect and determine pedaling more accurately and quickly than known methods and drive trains that detect pedaling solely based on measuring the driver torque at the pedal crankshaft 6. This increases safety when using the vehicle 2 with such a drive train 4 controlled by such a method. The activation or deactivation of the assistance by the drive motor 12 is thus carried out more quickly compared to known methods and drive trains that activate or deactivate the assistance solely based on the measured driver torque. Reference symbol 2 vehicles 4 Drivetrain 6 Wave 12 Drive motor 13 Sensor for measuring an angle signal of the shaft 14 Sensor for measuring a cadence of the wave 15 Torque sensor 16 Control device S1 Determining an angular acceleration of the shaft S2 Control of the drive motor S2.1 Activation of support by the drive motor S2.2 Switching off the support by the drive motor S3 Determining another measured variable on the drive train S3.1 Measuring a torque on the shaft S4 Determine whether a torque sensor fault condition exists S5 Measuring the angle signal of the shaft S6 Measuring the cadence of the wave QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] DE 10 2022 132 256 A1

[0003]

Claims

[1] Method for controlling a drive train (4) of a vehicle (2), wherein the drive train (4) has at least one shaft (6) which is accelerated when the vehicle (2) is driven by a driver, wherein the drive train (4) has a drive motor (12) for providing drive power to assist the driver of the vehicle (2) when driving the vehicle (2), wherein the method comprises the steps: determining (S1) an angular acceleration of the shaft (6); and controlling (S2) the drive motor (12), wherein the assistance provided by the drive motor (12) is switched on or off depending on the determined angular acceleration. [2] Method according to claim 1, characterized by , that during control (S2) an activation (S2.1) of the support by the drive motor (12) is carried out when the certain angular acceleration exceeds a first threshold value. [3] Method according to any one of the preceding claims, characterized by, that during control (S2) a shutdown (S2.2) of the support by the drive motor (12) is carried out if the specified angular acceleration falls below a second threshold value. [4] Method according to any one of the preceding claims, characterized by , that a further measurement variable (S3) is determined on the drive train (4), and that the control (S2) of the drive motor (12) is carried out depending on the further measurement variable determined. [5] Method according to claim 4, characterized by , that when determining (S3) the further measured quantity a measurement (S3.1) of a torque on the shaft (6) is carried out with a torque sensor (15), and that the control (S2) of the drive motor (12) is carried out depending on the measured torque. [6] Method according to claim 5, characterized by, that the control (S2) of the drive motor (12) is carried out depending on the determined angular acceleration when a measuring range of the torque sensor (15) is exceeded. [7] Method according to one of claims 5 or 6, characterized by , that a determination (S4) is carried out to determine whether a fault condition of the torque sensor (15) exists, and that the control (S2) of the drive motor (12) is carried out depending on the determined angular acceleration if a fault condition exists. [8] Drive train (4) for a vehicle (2), wherein the drive train (4) has at least one shaft (6) which is accelerated when the vehicle (2) is driven by a driver, wherein the drive train (4) has a drive motor (12) for providing drive power to assist the driver of the vehicle (2) when driving the vehicle (2), wherein the drive train (4) has a means for determining (S1) an angular acceleration of the shaft (6), and wherein the drive train (4) has a control device (16) for controlling (S2) the drive motor (12), wherein the assistance provided by the drive motor (12) is switched on or off depending on the determined angular acceleration. [9] Drive train (4) according to claim 8, characterized by , that the control device (16) is configured to perform steps of a method according to any one of claims 1 to 7. [10] Drive train (4) according to one of claims 8 or 9, characterized by, that the drive train (4) has a sensor (13) for measuring (S5) an angular signal of the shaft (6) and that the control device (16) is set up as the means for determining (S1) the angular acceleration as a function of the measured angular signal. [11] Drive train (4) according to any one of claims 8 to 10, characterized by , that the drive train (4) has a sensor (14) for measuring (S6) a cadence of the shaft (6) and that the control device (16) is set up as the means for determining (S1) the angular acceleration as a function of the measured cadence. [12] Vehicle (2) with a drive train (4) according to any one of claims 8 to 11.

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