Method for controlling a drive train of a muscle-powered vehicle, drive train and vehicle

Abstract

A method for controlling a drive train (4) of a human-powered vehicle (2) is described, wherein the drive train (4) has a pedal crankshaft (6), wherein the pedal crankshaft (6) is rotatably mounted on a frame (10) of the vehicle (2) by means of a bearing (8) of the vehicle (2), and wherein the drive train (4) has a drive motor (12) for providing drive force to assist a driver of the vehicle (2) in driving the vehicle (2). The method comprises determining (S1) a force acting from the pedal crankshaft (6) on the bearing (8) and controlling (S2) the drive motor (12), wherein the assistance by the drive motor (12) is switched on or off depending on the determined force. Furthermore, a drive train (4) for a human-powered vehicle (2) and a human-powered 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 human-powered vehicle. Furthermore, the present invention relates to a drive train for a human-powered vehicle and to a human-powered vehicle having such a drive train.

[0002] Human-powered vehicles, such as bicycles, e-bikes, pedelecs, or cargo bikes, can also have a drive motor to assist in propelling the vehicle. For example, a pedelec, as a human-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 the 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.For example, DE 10 2022 132 256 A1 describes that a driver torque is detected with a sensor and the drive motor is controlled depending on this.

[0003] The object of the invention is to improve the control of the drive motor of a muscle-powered vehicle as a function of the muscle power applied by the driver to drive the vehicle. This object is achieved by the subject matter of the independent claims.

[0004] In a first aspect, the invention relates to a method for controlling a drive train of a human-powered vehicle. The human-powered 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.

[0005] The drive train has a 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, with a pedal 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 propel the vehicle.

[0006] 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 while driving and, alternatively or additionally, to increase the range of the vehicle. The drive motor can be configured to provide drive power to relieve the driver. For example, drive power provided by the driver as muscle power and applied to the pedals and the crankshaft, 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.

[0007] The method includes determining a force acting from the crankshaft on the bearing. This force can be referred to as the bearing force. The determination can be or include a measurement. For example, the force acting from the crankshaft on the bearing can be measured using one or more sensors. If the force is measured using multiple sensors, the force can be resolved vectorially, for example. This allows the magnitude and direction of the force to be determined, for example.

[0008] The method further comprises controlling the drive motor, wherein the assistance by the drive motor is switched on depending on the determined force and alternatively or additionally switched off. For example, a first value of the force acting from the pedal crank on the bearing 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 force. The first force can correspond to a value which suggests that the rider is pedaling. When the assistance is switched on, for example, drive power is provided by the drive motor to drive the vehicle and is transferred, for example, to a driven wheel of the vehicle to drive the vehicle. For example, a second force can be determined at a second point in time, later than the first.This second force can be vectorial and, alternatively or additionally, different in magnitude from the first force. The second force can correspond to a value which suggests that the rider is not pedaling and, for example, is merely placing their feet on the pedals. For example, the second force can be zero or almost zero, meaning that, for example, no significant force can act on the bearing from the crankshaft or only a force which corresponds to placing the feet on the pedals without causing a significant rider torque. In this context, a significant force can, for example, be a force which generates a significant rider torque, whereby a significant rider torque can be a torque applied by the rider to effectively propel the vehicle.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 force. When the assistance is switched off, for example, no power is provided by the drive motor to propel the vehicle.

[0009] Such a method makes it particularly easy to detect when the rider is pedaling and, depending on this, to switch the drive motor assistance on or off. Pedaling can be determined by determining the force acting on the bearing from the crankshaft. For example, as described in the previous example, the first value of the force is determined, and thus it is recognized that the rider is pedaling. If the second value of the force is determined, for example, an almost negligible force, it is determined that the rider is not currently pedaling. The drive motor and, alternatively or additionally, the assistance provided by it are then switched off.

[0010] Switching off the drive motor's assistance when the rider is not pedaling may be necessary to increase the safety of human-powered vehicles. Compared to conventional methods, which use a torque sensor to measure and determine the torque applied by the rider to the crankshaft, this method makes it particularly easy to detect the rider's pedaling. This is achieved by determining the force acting from the crankshaft on the bearing. Determining the rider's torque with a special torque sensor is normally comparatively complex due to the rotating parts on the crankshaft.

[0011] In addition, the torque applied by the rider to the pedal crankshaft is very dependent on the crank angle of the crank arms on the pedal crankshaft. For example, the rider torque is small when the pedal crankshaft is in a vertical position, but when the crank arms of the pedal crankshaft are in a horizontal position, the rider torque is comparatively large. Accordingly, methods that measure the rider torque and use this measured rider torque to engage or disengage the drive motor are crank angle dependent. This means that the time required to detect pedaling can be longer than with the method provided here, which determines the force acting on the bearing from the pedal crankshaft. This means that with known methods and systems, there can be a significant time delay when engaging or disengaging the drive motor depending on the determined rider torque.This can happen, for example, when the rider begins pedaling with the crank arms in an almost vertical position. In this crank position, it can be difficult to determine rider torque and thus pedaling using conventional torque sensors, for example. This is uncomfortable for the rider because, for example, there is a significant delay when the drive motor assistance is activated. The method provided can reduce this delay. Accordingly, the method represents a way to activate or deactivate drive motor assistance depending on the rider's pedaling, and at the same time, the detection time for pedaling can be reduced, which can improve comfort and safety, for example.

[0012] Detection accuracy can also be improved in that there's no need to wait until the crank arms are horizontal, allowing the rider's torque to be accurately determined. Safety can be improved in that the rider can rely on the drive motor's activation or deactivation without significant delay, depending on pedaling and regardless of the crank position. Furthermore, determining the force acting from the crankshaft on the bearing is usually less complex than determining the torque at the crankshaft.

[0013] According to a further embodiment, the method can be characterized in that, during control, the assistance can be switched on by the drive motor if the determined force exceeds a first threshold. The switching on of the assistance can be a provision of drive force by the drive motor. The first threshold can, for example, be defined such that the force acting on the bearing from the pedal crankshaft is smaller than the first threshold if the rider merely places their feet on the pedals but does not pedal. The force acting on the bearing from the pedal crankshaft can be greater than the first threshold if the rider not only places their feet on the pedals but also pedals.

[0014] Thus, depending on the first threshold value, which can be stored, for example, on the control device of the vehicle as a hard-coded value, a limit value for the activation of the support by the drive motor can be objectively defined.

[0015] 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 force falls below a second threshold. Switching off the assistance can mean 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. If, for example, the first and second thresholds are the same, the assistance provided by the drive motor can be switched on above the threshold, and if the assistance provided by the drive motor can be switched off below the threshold. If the first and second thresholds are different, a hysteresis effect can be provided by the method, for example. The first threshold can be greater than the second threshold.If, for example, the first threshold is greater than the second threshold, the assistance can only be switched on when a greater force is applied, whereas the assistance can be switched off when a lower force is applied. This can ensure, for example, that the assistance is only switched on when the rider is pedaling with a certain minimum force and the force from the crankshaft acting on the bearing therefore exceeds this first threshold. At the same time, the smaller second threshold can ensure that the rider does not have to apply this comparatively high force from the crankshaft to the bearing through pedalling all the time before the assistance is switched off. This means that the assistance can be switched off by the drive motor in a defined manner when the second threshold is reached.

[0016] 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, the crank angle of the crank arms of the pedal crankshaft, the crank angular velocity or a rotational speed of a wheel, for example a driven wheel 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 control of the drive motor can be carried out depending on the determined further measured variable. In this case, the control of the drive motor can be carried out depending on the determined further measured variable and additionally depending on the determined force.Thus, the support by the drive motor can be switched on or off depending on the specific force as well as on the specific additional measured value.

[0017] This can, for example, further improve accuracy. Alternatively or additionally, it can make the process more fail-safe, as redundancy can be implemented.

[0018] According to a further embodiment, when determining the further measured variable, a torque on the pedal crankshaft can be determined. The torque can be determined, for example, using a sensor, such as a torque sensor, or alternatively or additionally using other means, for example, using an approximation method depending on further measured variables. The drive motor can be controlled depending on the determined torque. Controlling 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 force and depending on the determined torque on the pedal crankshaft.

[0019] This allows redundancy to be implemented through the method for controlling the drive motor and for providing assistance by the drive motor by switching it on or off. 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 compensate for the time delay that is present in conventional methods that only have a torque sensor for determining 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 depending on the determined force. Within a certain time window, this control of the assistance and the control of the drive motor can then be checked depending on the determined torque.This allows the determined driver torque to be used to control the drive motor to engage or disengage the drive motor's assistance, whereby the time delay can be compensated for using the determined bearing force. For example, with such a method, the driver torque can also be determined uniaxially, i.e., only with respect to one crank arm. This may be sufficient for the method described here, since the determined driver torque is used, for example, only to check the control of the drive motor for assistance by the drive motor depending on the determined force.

[0020] A second aspect of the present invention relates to a drive train for a human-powered vehicle. The human-powered vehicle can be a bicycle, e-bike, pedelec, or cargo bike. The drive train can have a 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, 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 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, for example a ball bearing, a needle bearing, or a roller bearing. The driving force of a driver of the vehicle can be absorbed via the pedal crankshaft to propel the vehicle.

[0021] 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.

[0022] The drive train may include a means for determining a force acting from the pedal crankshaft on the bearing, for example, a bearing force. The drive train may include one or more means for determining a force acting from the pedal crankshaft on the bearing. 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 force.

[0023] Thus, the drive train can be configured to engage or disengage the relief or assistance provided by the drive motor depending on the bearing force on the pedal crankshaft. 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.

[0024] According to a further embodiment, the drive train can be characterized in that the control device can be configured to execute steps of a method according to an embodiment of the first aspect of the present invention. The drive train can be configured to execute all steps of the method according to an embodiment of the first aspect. For example, the means for determining the force and the control device can be configured jointly to execute all steps of the method according to an embodiment of the first aspect.

[0025] According to a further embodiment, the drive train can be characterized in that the means for determining the force acting from the pedal crankshaft on the bearing is a sensor on an outer ring of the bearing for measuring the force. The outer ring can be a bearing shell of the bearing. The sensor can be arranged, for example, on a non-rotating outer ring of the bearing. This makes it particularly easy to measure the force on a non-rotating part, such as the non-rotating outer ring of the bearing.

[0026] According to a further embodiment, the drive train can be characterized in that the means for determining the force acting on the bearing from the pedal crankshaft can be a strain gauge on an outer ring of the bearing for determining a deformation in the outer ring of the bearing. The outer ring can be a bearing shell of the bearing. For example, the strain gauge can be arranged on a non-rotating outer ring of the bearing. The means can comprise one or more strain gauges for determining the deformation.

[0027] This makes it particularly easy to determine the deformation in the outer ring of the bearing and, depending on this, the force acting on the bearing from the crankshaft can then be determined.

[0028] A third aspect of the present invention relates to a human-powered vehicle with a drive train according to an embodiment of the second aspect of the present invention. The human-powered vehicle can be a bicycle, e-bike, pedelec, or cargo bike. 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 human-powered vehicle. Fig. Figure 2 shows schematically a muscle-powered vehicle with a drive train and a control device for carrying out the functions schematically shown in Fig. 1 depicted steps of the method for controlling the drive train.

[0029] Fig. 1 schematically shows steps of a method for controlling a drive train 4 of a muscle-powered vehicle 2. Fig. 2 schematically shows such a muscle-powered vehicle 2 with such a drive train 4. The drive train 4 has a pedal crankshaft 6. The pedal crankshaft 6 is rotatably mounted on a frame 10 of the vehicle 2 by means of a bearing 8 of the vehicle 2. The pedal crankshaft 6 also has pedals (not shown) that are rotatably mounted on crank arms (not shown) of the pedal crankshaft 6. The bearing 8 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.

[0030] Furthermore, the drive train 4 has a means 14 for determining S1 a force acting from the pedal crankshaft 6 on the bearing 8. The means 14 for determining S1 the force acting from the pedal crankshaft 6 on the bearing 8 is a sensor on a non-rotating outer ring of the bearing 8 for measuring S1.1 the force acting from the pedal crankshaft 6 on the bearing 8. The sensor, here a force sensor, is arranged between the bearing 8 and the frame 10. In an alternative embodiment, the means 14 for determining S1 the force acting from the pedal crankshaft 6 on the bearing 8 is a strain gauge. This strain gauge is arranged on a non-rotating outer ring of the bearing 8 for determining S1.2 a deformation in the outer ring of the bearing 8. In one embodiment, the drive train 4 has both a sensor for measuring S1.1 the force and a strain gauge for determining S1.2 the deformation.The determination S1 of the force acting from the crankshaft 6 on the bearing 8 then depends on both the measured force and the determined deformation.

[0031] Furthermore, the drive train 4 has a torque sensor 15. This torque sensor 15 is arranged between the pedal crankshaft 6 and the bearing 8. The torque sensor 15 is configured to determine S3 a further measured variable on the drive train 4. When determining S3 of the further measured variable, a determination S3.1 of a torque on the pedal crankshaft 6 is performed using the torque sensor 15.

[0032] The drive train 4 further comprises a control device 16 for controlling S2 of the drive motor 12. The control device 16 is communicatively connected to the torque sensor 15, the means 14 for determining S1 the force acting from the pedal crank 6 on the bearing 8, and to the drive motor 12. The assistance by the drive motor 12 is switched on or off depending on the determined force. The control device 16, the means 14, and the torque sensor 15 are configured to carry out steps of the process schematically shown in Fig. 1 shown procedure.

[0033] During control S2, the assistance provided by the drive motor 12 is switched on (S2.1) when the determined force exceeds a first threshold. Furthermore, during control S2, the assistance provided by the drive motor 12 is switched off (S2.2) when the determined force falls below a second threshold. In the embodiment shown, the first threshold is greater than the second threshold. In an alternative embodiment, the first and second thresholds are identical.

[0034] Furthermore, the control S2 of the drive motor 12 is performed as a function of the determined further measured variable. The control S2 of the drive motor 12 is performed 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 force, which is determined using the means 14, is checked using the determined torque.

[0035] 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. To determine whether the driver is pedaling or not, the crank arms of the pedal crankshaft 6 do not necessarily have to be in a horizontal position. 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 based solely on determining the driver's torque on 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 support by the drive motor 12 is thus carried out more quickly compared to known methods and drive trains which activate or deactivate the support solely based on the measured driver torque. Reference symbol 2 vehicles 4 Drivetrain 6 Crankshaft 8 warehouses 10 frames 12 Drive motor 14 Means for determining a force acting from the pedal crank on the bearing 15 Torque sensor 16 Control device S1 Determine the force acting from the crankshaft on the bearing S1.1 Measuring the force on an outer ring of the bearing S1.2 Determining a deformation in the outer ring of the bearing 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 Determining a torque of a pedal crankshaft 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

[0002]

Claims

[1] Method for controlling a drive train (4) of a muscle-powered vehicle (2), wherein the drive train (4) has a pedal crankshaft (6), wherein the pedal crankshaft (6) is rotatably mounted on a frame (10) of the vehicle (2) by means of a bearing (8) of the vehicle (2), and wherein the drive train (4) has a drive motor (12) for providing drive force to assist a driver of the vehicle (2) in driving the vehicle (2), wherein the method comprises the steps of: determining (S1) a force acting from the pedal crankshaft (6) on the bearing (8); and controlling (S2) the drive motor (12), wherein the assistance by the drive motor (12) is switched on or off depending on the determined force. [2] Method according to claim 1, characterized bythat during control (S2) a switching on (S2.1) of the support by the drive motor (12) is carried out when the determined force exceeds a first threshold value. [3] Method according to one of the preceding claims, characterized by that during control (S2) a switching off (S2.2) of the support by the drive motor (12) is carried out if the determined force falls below a second threshold value. [4] Method according to one of the preceding claims, characterized by that a determination (S3) of a further measured variable is carried out on the drive train (4), and that the control (S2) of the drive motor (12) is carried out as a function of the determined further measured variable. [5] Method according to claim 4, characterized bythat when determining (S3) the further measured variable, a determination (S3.1) of a torque on the pedal crankshaft (6) is carried out, and that the control (S2) of the drive motor (12) is carried out as a function of the determined torque. [6] Drive train (4) for a muscle-powered vehicle (2), wherein the drive train (4) has a pedal crankshaft (6), wherein the pedal crankshaft (6) is rotatably mounted on a frame (10) of the vehicle (2) by means of a bearing (8) of the vehicle (2), wherein the drive train (4) has a drive motor (12) for providing drive force to assist a driver of the vehicle (2) in driving the vehicle (2), wherein the drive train (4) has a means (14) for determining (S1) a force acting from the pedal crankshaft (6) on the bearing (8), and wherein the drive train (4) has a control device (16) for controlling (S2) the drive motor (12), wherein the assistance by the drive motor (12) is switched on or off depending on the determined force. [7] Drive train (4) according to claim 6, characterized bythat the control device (16) is arranged to carry out steps of a method according to one of claims 1 to 5. [8] Drive train (4) according to one of claims 6 or 7, characterized by that the means (14) for determining (S1) the force acting from the pedal crankshaft (6) on the bearing (8) is a sensor on an outer ring of the bearing (8) for measuring (S1.1) the force. [9] Drive train (4) according to one of claims 6 to 8, characterized by that the means (14) for determining (S1) the force acting from the pedal crankshaft (6) on the bearing (8) is a strain gauge on an outer ring of the bearing (8) for determining (S1.2) a deformation in the outer ring of the bearing (8). [10] Muscle-powered vehicle (2) with a drive train (4) according to one of claims 6 to 9.

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