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

Abstract

A method for controlling a drive train (4) of a human-powered vehicle (2) is described, wherein the drive train (4) has pedals (5), 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 applied by the driver to the pedals (5) and controlling (S2) the drive motor (12) as a function of 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

Technical area

[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. State of the art

[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, DE102022132256A1 describes that a driver torque is detected with a sensor and the drive motor is controlled depending on this. Description of the invention

[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 pedals. Furthermore, the drive train can have a pedal crankshaft, and 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. 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.

[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 applied by the driver to the pedals. This force may be referred to as pedal force. Determining the pedal force may be or include measuring. For example, the force applied by the driver to the pedals may be measured using one or more sensors. The pedal force may be determined in terms of magnitude. The pedal force may be determined for each pedal using one sensor per pedal. The total force applied by the driver to the pedals may be a sum of the individual forces applied per pedal.

[0008] The method further comprises controlling the drive motor as a function of the determined force. The control can be a control and alternatively or additionally a regulation of the drive motor as a function of the determined force, wherein the determined force can be used, for example, as a controlled variable. For example, a first force can be determined for a first point in time and a second force can be determined for a second point in time. The first and second points in time can be different, and the first and second forces can have different magnitudes. Controlling the drive motor at the first point in time can be different from controlling the drive motor at the second point in time. For example, a function can represent a relationship between a power provided by the drive motor, a torque provided, and alternatively or additionally a speed provided, and the determined force.Depending on the specific force, the drive motor can be controlled differently, for example depending on the function, in order to provide a different level of power.

[0009] With such a method, it is particularly easy to detect when the rider is pedaling and to control the drive motor accordingly. Pedaling can be determined by determining the force applied by the rider to the pedals. For example, as described in the example above, the first force value is determined, and thus it is recognized that the rider is pedaling. If the second force value is determined, for example an almost negligible force which is smaller than the first force value, it is determined that the rider is not currently pedaling. The drive motor and, alternatively or additionally, the assistance provided by it are then controlled differently than when the rider is pedaling. The pedal force can therefore be used to control the drive motor, whereas in known methods the pedal force is only used for training purposes.

[0010] 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 applied by the rider to the pedals. 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 highly 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 control 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 for determining the force applied by the rider to the pedals. This can result in a significant time delay in controlling the drive motor depending on the determined rider torque using known methods and systems.This can be the case, for example, if 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 long time delay in controlling the drive motor and the control of the drive motor can change significantly after the rider has already been pedaling for some time. The method provided can reduce this time delay. Accordingly, the method represents a way of controlling the drive motor 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 controlling the drive motor without significant delay, depending on pedaling and independent of the crank position. Furthermore, determining the force applied by the rider to the pedals is usually less complex than determining the torque at the crankshaft.

[0013] According to a further embodiment, the method can be characterized in that 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 applied by the driver to the pedals 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 driver is pedaling. When the assistance is switched on, for example, drive power is provided by the drive motor to drive the vehicle and 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 different in magnitude from the first force. The second force 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, the second force can be zero or almost zero, meaning that, for example, no significant force is applied to the pedals or only a force corresponding to placing the feet on the pedals without causing a significant driver torque. In this context, a significant force can, for example, be a force which generates a significant driver torque, whereby a significant driver torque can be a torque applied by the driver to effectively propel the vehicle. The drive motor can be controlled in such a way that the assistance from the drive motor is switched off depending on this second force.For example, when the assistance is switched off, no driving force is provided by the drive motor to drive the vehicle.

[0014] 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. Switching off the assistance from the drive motor when the rider is not pedaling can be necessary to increase the safety of human-powered vehicles. Furthermore, with known methods, a time delay can occur due to the determination of pedaling using a torque sensor. This can be uncomfortable for the rider because, for example, there is a significant delay in switching on the assistance from the drive motor. Thus, the assistance from the drive motor can be switched on or off depending on the force applied by the rider to the pedals.

[0015] 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. Switching on the assistance can involve providing drive force by the drive motor. The first threshold can be defined, for example, such that the force applied by the rider to the pedals is less than the first threshold if the rider merely places their feet on the pedals but does not pedal. The force applied by the rider to the pedals can be greater than the first threshold if the rider not only places their feet on the pedals but also pedals.

[0016] 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.

[0017] 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 higher than the second threshold, the assistance can only be switched on at a higher force, whereas the assistance can be switched off at a lower force. This can ensure, for example, that the assistance is only switched on when the rider pedals with a certain minimum force and the force applied to the pedals 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 to the pedals all the time by pedaling before the assistance is switched off. This means that the assistance can be switched off by the drive motor in a defined manner above the second threshold.

[0018] 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.For example, the activation or deactivation of the support by the drive motor can be carried out both depending on the specific force and depending on the specific additional measured value.

[0019] This can, for example, further improve accuracy. Alternatively or additionally, it can make the process more fail-safe, as redundancy can be implemented.

[0020] According to a further embodiment, the drive train can have a pedal crankshaft, and 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. In this case, the drive motor can be controlled and thus, for example, the activation or deactivation of the assistance by the drive motor can be carried out both depending on the determined force and depending on the determined torque on the pedal crankshaft.

[0021] This method can therefore implement redundancy when controlling the drive motor and, for example, when providing assistance from 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 control the drive motor based on this. With the method presented here, for example, the drive motor can initially be controlled solely as a function of the determined force. This control of the drive motor as a function of the determined torque can then be checked within a specific time window.This allows the determined driver torque to be used to control the drive motor, for example, to engage or disengage the drive motor's assistance, whereby the time delay can be compensated for using the determined pedal force. For example, with such a method, the driver torque can also be determined uniaxially, for example, 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 as a function of the determined force.

[0022] 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 pedals. 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 pedals and the pedal crankshaft to propel the vehicle.

[0023] 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.

[0024] The drivetrain may include a means for determining a force applied to the pedals by the driver of the vehicle, for example, a pedal force. The drivetrain may include one or more means for determining a force applied to the pedals by the driver. Furthermore, the drivetrain may include a control device for controlling the drive motor depending on the determined force. For example, the assistance provided by the drive motor may be activated and alternatively or additionally deactivated depending on the determined force.

[0025] Thus, the drive train can be configured to control the drive motor, for example, to activate or deactivate the relief or assistance provided by the drive motor, depending on the pedal force. 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.

[0026] 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.

[0027] According to a further embodiment, the drive train can be characterized in that the means for determining the force applied by the driver to the pedals is a sensor for each pedal for measuring the force. The sensor can, for example, be arranged in the pedal, for example below a surface of the pedal on which the driver places their foot to pedal. The pedal itself can be rotatably mounted on a crank arm, but the sensor for measuring the force can be arranged stationary in the surface of the pedal. This makes it particularly easy to measure the force on a non-rotating part, for example because the sensor is arranged stationary in the surface of the pedal and does not rotate relative to the surface of the pedal and thus relative to the pedal. The drive motor can thus be controlled depending on an easily measured pedal force.

[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. Short description of the characters 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. Detailed description of embodiments

[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 5, which are rotatably arranged 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 applied by the driver to the pedals 5. The means 14 for determining S1 the force applied by the driver to the pedals 5 is a sensor for each pedal 5 for measuring S1.1 of the force. The sensor, here a force sensor, is arranged in the pedal 5.

[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 the drive motor 12. The control device 16 is communicatively connected to the torque sensor 15, the pedals 5 and thus to the means 14 for determining S1 the force applied by the driver to the pedals 5, as well as to the drive motor 12. The control S2 of the drive motor 12 is carried out depending on the determined force. 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.Thus, the control S2 and the switching on or off of the assistance by the drive motor 12 are carried out more quickly compared to known methods and drive trains which carry out the control, and for example also the switching on or off of the assistance, only based on the measured driver torque. Reference symbol 2 vehicles 4 Drivetrain 5 pedals 6 Crankshaft 8 warehouses 10 frames 12 Drive motor 14 Means for determining a force applied by the driver to the pedals 15 Torque sensor 16 Control device S1 Determine the force applied by the driver to the pedals S1.1 Measuring force 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 102022132256A1

[0002]

Claims

[1] Method for controlling a drive train (4) of a muscle-powered vehicle (2), wherein the drive train (4) has pedals (5), 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 comprising the steps of: determining (S1) a force applied by the driver to the pedals (5); and controlling (S2) the drive motor (12) as a function of the determined force. [2] Method according to claim 1, characterized by that the support by the drive motor (12) is switched on or off depending on the determined force. [3] Method according to claim 2, characterized by that 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. [4] Method according to one of claims 2 or 3, 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. [5] 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. [6] Method according to claim 5, characterized by that the drive train (4) has a pedal crankshaft (6), that 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. [7] Drive train (4) for a muscle-powered vehicle (2), wherein the drive train (4) has pedals (5), 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 applied by a driver of the vehicle (2) to the pedals (5), and wherein the drive train (4) has a control device (16) for controlling (S2) the drive motor (12) as a function of the determined force. [8] Drive train (4) according to claim 7, characterized by that the control device (16) is arranged to carry out steps of a method according to one of claims 1 to 6. [9] Drive train (4) according to one of claims 7 or 8, characterized bythat the means (14) for determining (S1) the force applied by the driver to the pedals (5) is a sensor per pedal (5) for measuring (S1.1) the force. [10] Muscle-powered vehicle (2) with a drive train (4) according to one of claims 7 to 9.

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