Method for operating a drive assembly of a bicycle

Abstract

The invention relates to a method for operating a drive assembly (10) of a bicycle, in particular an electric bicycle (100), having the steps of: detecting (22) the pedal frequency, detecting (23) a first rear wheel rotational speed, in particular directly by means of a rotational speed sensor, determining (24) a second rear wheel rotational speed using the detected pedal frequency, determining (25) a rotational speed threshold value by multiplying the determined first rear wheel rotational speed by a specified factor, and detecting (26) an active rider intervention if the determined second rear wheel rotational speed at least equals the determined rotational speed threshold value.

Description

[0001] Description

[0002] title

[0003] Method for operating a drive system of a bicycle

[0004] State of the art

[0005] The present invention relates to a method for operating a drive arrangement of a bicycle, and to a bicycle.

[0006] Bicycles, including e-bikes, are known to have a drive unit that generates motor torque to assist the rider's manual pedaling. Typically, the motor torque is generated in response to the rider's pedaling force. This often involves directly detecting the rider's pedaling torque, for example, using sensors. This frequently requires a complex and costly drive system for the e-bike.

[0007] Disclosure of the invention

[0008] In contrast, the method according to the invention with the features of claim 1 is characterized in that intervention detection on a drive assembly of a bicycle can be provided in a particularly simple and cost-effective manner. In particular, this allows the actuation of a motor in the case of an electric bicycle to be carried out in a particularly simple, reliable and cost-effective manner. This is achieved according to the invention by a method for operating a drive assembly of a bicycle, in particular an electric bicycle, comprising the steps:

[0009] Capturing a cadence,

[0010] Detecting an initial rear wheel speed,

[0011] Determining a second rear wheel speed using the recorded cadence, determining a speed threshold by multiplying the determined first rear wheel speed by a predetermined factor, and detecting active rider intervention when the determined second rear wheel speed is at least equal to the determined speed threshold.

[0012] Preferably, the cadence is detected using at least one sensor. Detection can be direct or, alternatively, indirect, for example by conversion.

[0013] In particular, the first rear wheel rotation speed is directly recorded, for example using a speed sensor. Alternatively, the first rear wheel rotation speed can be calculated from a recorded bicycle speed.

[0014] A constant numerical value is preferably considered the predetermined factor.

[0015] In particular, active rider intervention is defined as any interaction between the rider and the bicycle's drivetrain that generates a propulsive torque. This means that during active rider intervention, the rider's pedaling force at least partially generates a propulsive torque for the bicycle. In other words, during active rider intervention, the drivetrain is tensioned by the rider's pedaling force.

[0016] In other words, the method determines the instantaneous rear wheel speed in two different ways: directly and based on the recorded cadence. For example, the first rear wheel speed can be considered the actual rear wheel speed, while the second can be considered the theoretical rear wheel speed. By comparing the rear wheel speeds determined in this way, taking into account the predetermined factor and thus the speed threshold, active rider intervention can be detected when the second rear wheel speed reaches or exceeds the determined speed threshold.

[0017] This method offers the advantage of providing a particularly simple, cost-effective, and reliable way to obtain information about the current state of the cyclist's interaction with the drivetrain. By analyzing rear wheel rotation speeds determined in various ways, a particularly cost-effective data acquisition method can be provided, as very simple and inexpensive sensors can be used. Furthermore, the calculations can be performed easily and efficiently. Moreover, precise knowledge of the intervention state enables a more flexible and optimized operation of the bicycle. For example, in the case of an e-bike, the motor can be optimized based on the detected active rider input. This results in a particularly high level of user comfort for the cyclist.

[0018] The dependent claims describe preferred embodiments of the invention.

[0019] Preferably, the predetermined factor is less than 1. Particularly preferably, the predetermined factor is at least equal to 0.5. This allows for particularly reliable and early detection of active driver intervention. Preferably, the lower the predetermined factor, the earlier the driver intervention can be detected. Thus, by flexibly adjusting the factor, optimized detection of driver intervention is possible, for example, to provide a particularly high level of driving comfort for the driver.

[0020] Preferably, the method further comprises the step of detecting a period of free pedaling, particularly after the end of a detected rider intervention, and when the determined second rear wheel rotation speed is less than or equal to the determined rotation speed threshold. In other words, free pedaling is detected if pedaling was previously performed at a sufficiently high cadence and then the second rear wheel rotation speed becomes less than or equal to the determined rotation speed threshold. For example, free pedaling is alternatively or additionally preferably detected if the detected bicycle speed and / or the detected cadence is less than a predetermined free pedaling threshold, wherein, in particular, the predetermined free pedaling threshold can have a value of 3 rpm in the case of the cadence under consideration. Alternatively or additionally preferably, the free pedaling threshold can have a value of 2 km / h in the case of the detected bicycle speed.In particular, "free pedaling" is defined as a riding condition in which the bicycle is moving and some pedal movement may be present, but no significant pedaling torque is generated by the rider. This means that, for example, the crank mechanism can be moved by the rider, but no driving torque is generated by the rider's pedaling force. By additionally determining free pedaling, a particularly reliable and accurate determination of the bicycle's current riding condition can be achieved, enabling, for example, the provision of riding functions in a particularly flexible and reliable manner.

[0021] Preferably, the method further comprises the step of detecting when the bicycle is stationary if the detected bicycle speed is less than or equal to a predetermined standstill threshold. Preferably, the standstill is detected if, in addition, the detected cadence is less than or equal to a predetermined standstill threshold. The standstill threshold is preferably less than or equal to 2 km / h in the case of bicycle speed. More preferably, the standstill threshold can be less than or equal to 2 rpm in the case of cadence. This allows for the determination and provision of further advantageously usable functions of the bicycle's current operating state, for example, to enable energy- and cost-efficient operation of the bicycle.

[0022] Preferably, the method further comprises the step of detecting a motion initiation when the detected bicycle speed is greater than or equal to a predetermined initialization speed and when, simultaneously, the detected cadence is less than or equal to a predetermined initialization cadence. A motion initiation can be, for example, the bicycle starting up. In this case, the bicycle may, for example, after the drive system has been switched on, be moving at a certain positive speed or begin to roll from a standstill, for example, without any pedaling action by the rider. Preferably, the predetermined initialization speed is 2 km / h. For example, the predetermined initialization cadence is 2 rpm.This allows for the identification of another characteristic riding condition of the bicycle, and this knowledge can be advantageously used for other riding functions. For example, future riding conditions can be estimated based on this, which allows for the particularly reliable and time-efficient selection of corresponding bicycle functions.

[0023] Preferably, the first rear wheel speed is determined using a known rear wheel circumference. That is, the first rear wheel speed is calculated, preferably exclusively, using the known rear wheel circumference and the recorded bicycle speed. This allows for a particularly simple and precise determination of the first rear wheel speed.

[0024] Preferably, the second rear wheel speed is determined using an instantaneous gear ratio. The instantaneous gear ratio is specifically defined as the overall gear ratio between a crank mechanism with the cranks and the rear wheel of the bicycle. That is, the second rear wheel speed is determined based on the mechanical relationship between crank rotation and rear wheel rotation, particularly during active rider input. This allows the theoretically calculated second rear wheel speed to be determined in a particularly simple and reliable manner.

[0025] The instantaneous gear ratio is particularly preferred when determined based on the recorded cadence and bicycle speed. This means the instantaneous gear ratio is calculated based on the movement parameters of the bicycle's drivetrain and the bicycle speed. This allows, for example, the instantaneous gear ratio to be provided simply and reliably using existing, simple, and inexpensive sensors, enabling a particularly precise and straightforward determination of the rider's active intervention.

[0026] Preferably, the drive arrangement comprises a motor configured to generate motor torque to assist the rider's pedaling force. The method preferably further includes the step of generating motor torque only during detected active rider input. That is, the generation of motor torque, preferably controlled, only occurs when the method positively detects active rider input. In particular, the generation of motor torque, preferably actively controlled, is prevented when no active rider input is detected. This allows the motor torque to be provided simply and with particular precision only while the rider is actively pedaling, i.e., actively generating at least a portion of the propulsive torque to move the bicycle forward using muscle power.By precisely detecting the active rider input and adjusting the motor control accordingly, a particularly reliable and comfortable operation of the bicycle can be achieved.

[0027] Preferably, the generation of engine torque depends on a ratio between the first and second rear wheel speeds. Alternatively or additionally, preferably, engine torque generation is prevented when the pedal is released. In particular, the engine torque can be generated gradually depending on the ratio between the first and second rear wheel speeds if this ratio is greater than or equal to a predetermined threshold.

[0028] Furthermore, the invention leads to an electric bicycle drive system comprising a drive assembly and a control unit. The control unit is configured to carry out the described method. The invention also relates to a bicycle, in particular an electric bicycle with an electric bicycle drive system.

[0029] Preferably, the drive arrangement includes a motor. Preferably, the control unit is additionally configured for controlled actuation of the motor. The motor is preferably arranged on a hub of the bicycle, preferably a rear wheel hub. In other words, the bicycle is an electric bicycle with a hub drive. Alternatively, and preferably, the motor can also be arranged in the area of ​​a bottom bracket of the bicycle, so that it is, in particular, a bicycle with a mid-drive motor.

[0030] The electric bicycle drive system, drive arrangement, or bicycle / electric bicycle is particularly preferably designed to be completely free of torque sensors and / or bearing force sensors. This means that, in particular, no torque sensor and / or bearing force sensor is present for detecting pedal actuation. This allows for a particularly simple and cost-effective bicycle design. The drive arrangement is operated without torque sensors and / or bearing force sensors using the method according to the invention. The method according to the invention is used to operate the drive arrangement without torque sensors and / or bearing force sensors. This means that no sensor data from a torque sensor and / or a bearing force sensor is used to detect pedal actuation.

[0031] Brief description of the drawings

[0032] The invention is described below with reference to an exemplary embodiment in conjunction with the figures. In the figures, functionally identical components are each identified by the same reference numerals. The figures show:

[0033] Figure 1 shows a simplified schematic view of a bicycle in which a method according to a preferred embodiment of the invention is carried out.

[0034] Figure 2 shows a highly simplified schematic view of the method according to the invention.

[0035] Figure 3 shows a highly simplified schematic detail of the method according to the invention.

[0036] Figure 4 shows a further highly simplified schematic detail of the method according to the invention.

[0037] Figure 5 shows a further highly simplified schematic detail of the method according to the invention, and

[0038] Figure 6 shows an exemplary cadence curve over time, which occurs during the

[0039] The procedure can be used to carry it out.

[0040] Embodiments of the invention

[0041] Figure 1 shows a simplified schematic view of a bicycle 100 with a drive arrangement 10, in which a method 1 according to a preferred embodiment of the invention is carried out. The bicycle 100 is an electric bicycle 100, which has a hub drive. In detail, the electric bicycle 100 comprises a motor which is arranged on a hub of a rear wheel 110 of the electric bicycle 100.

[0042] In an alternative (not shown) preferred embodiment, it can also be an electric bicycle 100 with a mid-drive motor, in which the motor is arranged in the area of ​​a bottom bracket.

[0043] In particular, the motor is designed as an electric motor and can be supplied with electrical energy by means of an electrical energy storage device 109 of the electric bicycle 100.

[0044] A motor torque generated by the motor of the drive arrangement 10 can provide motor support to the pedaling force generated by muscle power of a rider of the electric bicycle 100.

[0045] The rider's muscle power can be applied via a crank mechanism comprising cranks 104. The crank mechanism is connected to the hub of the rear wheel 110 via a chain drive.

[0046] The drive arrangement 10 also includes a gearshift 5, which has several different gears. The gearshift 5 is preferably designed as a derailleur gearshift, with several different sprockets.

[0047] Preferably, the gear shift 5 can be operated manually by the rider of the electric bicycle 100, and / or automatically controlled by a control unit 50 of the electric bicycle 100.

[0048] The control unit 50 of the electric bicycle 100 can, for example, be integrated into the drive arrangement 10. The control unit 50 is configured for the controlled actuation of the motor and for carrying out the method 1 of the preferred embodiment.

[0049] When the electric bicycle 100 is in operation, the motor torque is provided depending on the pedaling force generated by the rider. The method 1 according to the invention offers the advantage that the operation of the electric bicycle 100 can be enabled in a particularly simple and cost-effective manner. In detail, operation of the motor dependent on pedal actuation can be enabled, thereby eliminating the need for torque sensors and bearing force sensors. The electric bicycle 100 is preferably designed without torque sensors and without bearing force sensors.

[0050] The inventive method 1 is described in detail below with reference to Figures 2 to 6.

[0051] Method 1 essentially comprises three main functions: an intervention detection 11, a transmission ratio determination 12, and a switching detection 13 (see Figure 2). It should be noted that these three main functions can at least partially overlap, interact with each other, and be interdependent. Based on the aforementioned functions of Method 1, the motor torque 30 is generated.

[0052] Figure 3 shows a highly simplified schematic detail of method 1 of the preferred embodiment. Figure 3 shows the intervention detection 11 in more detail. This preferably includes simultaneously detecting 21 the speed of the electric bicycle 100, detecting 23 a first rear wheel rotation speed, and detecting 22 a pedaling cadence.

[0053] The bicycle speed can be calculated based on the recorded first rear wheel rotation speed and an instantaneous gear ratio, or alternatively, preferably, it can be recorded directly using a speed sensor.

[0054] The first rear wheel rotation speed is preferably detected directly by means of a speed sensor.

[0055] The cadence is preferably recorded using a cadence sensor.

[0056] Furthermore, a second rear wheel speed is determined using the detected cadence and an instantaneous gear ratio of the drive train of the electric bicycle 100. The instantaneous gear ratio can preferably be provided using function 12 of method 1, as described later.

[0057] Subsequently, a speed threshold is determined by multiplying the determined first rear wheel speed by a predetermined factor. The factor is preferably less than 1 and in particular has the value 0.7.

[0058] Based on the determined parameters, a detection step 20 is then carried out, in which the presence of different operating states of the electric bicycle 100 can be detected.

[0059] Active rider intervention is detected when the measured second rear wheel speed is at least equal to the measured speed threshold. This means that in this case, it is recognized that the rider is actively interacting with the drivetrain and contributing to the propulsive torque of the e-bike by means of their pedaling force.

[0060] In method 1, the generation of engine torque occurs only when active driver intervention is detected. In other operating states, where no active driver intervention is detected, no engine torque is provided and / or the provision of engine torque is actively prevented.

[0061] Alternatively or additionally, preferably, the generation of motor torque 30 can be achieved depending on the ratio of the first rear wheel speed and the second rear wheel speed. In particular, the assistance is gradually released depending on the speed ratio when the ratio of the two rear wheel speeds exceeds a certain value.

[0062] Detection step 20 further includes the detection 27 of free-pedaling if, after the end of a detected rider intervention, the determined rear wheel rotational speed is less than or equal to the determined rotational speed threshold. This means that in this case, the electric bicycle 100 can move at a certain positive speed and a certain cadence may also be present, but there is no rider intervention. That is, pedaling does not contribute to the propulsive torque of the electric bicycle 100.

[0063] Furthermore, detection step 20 includes the detection 28 of a standstill of the electric bicycle 100 if the detected bicycle speed and, additionally, the detected cadence are less than or equal to a respective predefined standstill threshold. That is, at low bicycle speed and low cadence, the standstill of the electric bicycle 100 is detected.

[0064] Furthermore, detection step 20 includes the detection 29 of a movement initiation of the electric bicycle 100 if the detected bicycle speed is greater than or equal to a predetermined initialization speed and if, at the same time, the detected cadence is less than or equal to a predetermined initialization cadence. That is, in this case, a positive speed may be present, particularly after the drive arrangement 10 of the electric bicycle 100 has been switched on, or, for example, the electric bicycle 100 may start rolling from a standstill, for example due to a slope, without a cadence being present.

[0065] Figure 4 shows a further highly simplified schematic detail of method 1 of the preferred embodiment of the invention. Figure 4 illustrates the determination of the translation ratio 12 in more detail.

[0066] In method 1, two different translation ratios are used simultaneously at all times: a continuous first translation ratio and a global second translation ratio.

[0067] The global second transmission ratio is determined in step 42 and assumed to be the actual instantaneous transmission ratio of the drive arrangement 10.

[0068] The second gear ratio provided in step 42 is used for further functions of the drive arrangement 10 and / or the electric bicycle 100. In detail, the second gear ratio determined in step 42 is used to generate the motor torque, which is generated during active rider intervention depending on the determined gear ratio.

[0069] Furthermore, the process continuously determines the first gear ratio (41), which is calculated based on the recorded cadence and bicycle speed. The recorded cadence is also filtered using a first-order low-pass filter. The first gear ratio is then calculated as the ratio of a determined rear wheel rotational speed to the filtered cadence. The rear wheel rotational speed is calculated using the recorded bicycle speed and the previously known rear wheel circumference.

[0070] Under certain conditions, an update (43) of the second translation ratio is performed using the current first translation ratio. This means that when update 43 is executed, the currently valid value of the global second translation ratio is replaced by the current value of the first translation ratio. Specifically, the current global second translation ratio is maintained as long as no update (43) is requested.

[0071] Update 43 is performed when the following criteria are met simultaneously:

[0072] - the recorded bicycle speed is greater than or equal to a predetermined threshold,

[0073] - active driver intervention is detected by means of intervention detection 11 ,

[0074] - a predetermined trigger signal is detected, and

[0075] - a driving condition 15 of the electric bicycle 100 is detected.

[0076] Driving condition 15 is specifically defined as a state of the electric bicycle 100 in which there is no restart from a standstill. This means that the electric bicycle 100 moves at a predetermined minimum speed.

[0077] The detection of the trigger signal is indicated by step 16 in Figure 4. The trigger signal comprises a gear change signal, which is generated in response to a detected gear change. The gear change detection is performed using function 13 of method 1, as described later.

[0078] Alternatively or additionally, preferably, the trigger signal includes a monitoring signal, which is generated by a monitoring unit. For example, such a monitoring unit can also be referred to as a "watchdog." The monitoring signal is generated by the monitoring unit based on a comparison of the first and second gear ratios. Here, the difference between the first and second gear ratios is integrated over time, and the monitoring signal is generated when the result of the integration reaches or exceeds a predetermined trigger threshold.

[0079] Alternatively or additionally, preferably, the monitoring unit can generate the monitoring signal after a predetermined period of time.

[0080] The gear ratio determination 12 thus allows for a particularly simple and cost-effective way to precisely determine and provide the current estimated actual gear ratio. The determination of the continuous first gear ratio can be carried out in a particularly simple manner and without complex and expensive sensor technology. Because the second gear ratio actually used is only updated by the first gear ratio according to certain criteria, a high degree of precision in the gear ratio used can be provided in a simple way, especially since large fluctuations in the first gear ratio, which can occur, for example, due to operational reasons in certain operating situations of the electric bicycle 100, are not taken into account.

[0081] Figure 5 shows a further highly simplified schematic detail of method 1 of the preferred embodiment of the invention. In Figure 5, the shift detection 13 is shown in a highly simplified schematic representation. The shift detection 13 is based on the detection of jumps 81 in the temporal course of the cadence 80, as shown in a simplified example in Figure 6.

[0082] In the switching detection 13, the temporal cadence profile 80 is first recorded 51 during the operation of the electric bicycle 100. Based on the temporal cadence profile 80, a derivative function of the temporal cadence profile 80 is then determined 52.

[0083] Furthermore, a crank acceleration is determined 53 using the determined derivative function. In particular, in step 53, a time course of the crank acceleration is generated based on the derivative function. Preferably, the determination 53 of the crank acceleration also includes filtering the determined crank acceleration using a low-pass filter.

[0084] The detection of a switching process occurs when the following criteria are met simultaneously:

[0085] - The measured crank acceleration exceeds a predetermined acceleration threshold,

[0086] - a maximum is detected in the temporal progression of the determined crank acceleration, and

[0087] - a driving condition 15 of the electric bicycle 100 is detected.

[0088] Preferably, the driving state 15 of the electric bicycle 100 can be recognized, in particular analogous to the function 12 described above, if the detected cadence is at least equal to a predetermined driving cadence and if, at the same time, a detected bicycle speed is at least equal to a predetermined driving speed.

[0089] Preferably, the determination and provision of the crank acceleration is carried out in discrete sequential values. The maximum in the temporal course of the crank acceleration is identified accordingly based on the discrete sequential values ​​of the determined crank acceleration, particularly when an increasing value is detected in a previous epoch of the crank acceleration and a decreasing value is detected in the current epoch. The shift detection 13 is thus based on the detection of large, abrupt changes in cadence that occur during shifting operations when the power transmission to the sprockets of the cassette is interrupted for a brief moment during the shifting process.

[0090] The specific criteria of the inventive method 1 allow for a particularly simple execution of the detection process while simultaneously enabling particularly precise detection of the switching operations. In particular, false detections can be reliably avoided as a result.

[0091] A switching operation detected in step 54 can then be used to initiate a recalculation of the transmission ratio in the transmission ratio determination 12, as described above.

Claims

Claims 1. Method for operating a drive arrangement (10) of a bicycle, in particular an electric bicycle (100), comprising the steps of: detecting (22) a cadence, Detecting (23) a first rear wheel speed, in particular directly by means of a speed sensor, Determining (24) a second rear wheel speed using the detected cadence, Determine (25) a speed threshold by multiplying the determined first rear wheel speed by a predetermined factor, and detect (26) an active rider intervention when the determined second rear wheel speed is at least equal to the determined speed threshold.

2. The method according to claim 1, wherein the predetermined factor is less than 1, preferably at least equal to 0.

5.

3. A method according to any of the preceding claims, further comprising the step of: Detect (27) a free pedaling when, in particular after the end of a detected driver intervention, the determined second rear wheel speed is less than or equal to the determined speed threshold.

4. A method according to any of the preceding claims, further comprising the step of: Detect (28) a standstill when a determined bicycle speed, in particular and the recorded cadence, is less than or equal to a predetermined standstill threshold.

5. A method according to any of the preceding claims, further comprising the step of: Detect (29) a movement initiation when the detected bicycle speed is greater than or equal to a predetermined initiation speed and when the detected cadence is less than or equal to a predetermined initiation cadence.

6. Method according to one of the preceding claims, wherein the first rear wheel rotational speed is determined using a previously known rear wheel circumference.

7. Method according to one of the preceding claims, wherein the second rear wheel speed is determined by means of an instantaneous transmission ratio.

8. Method according to claim 7, wherein the instantaneous transmission ratio is determined based on the detected cadence and the detected bicycle speed.

9. A method according to any of the preceding claims, further comprising the step of: Generating (30) an engine torque only during the detected active driver intervention.

10. Method according to any of the preceding claims, further comprising the step of: Generating (30) the engine torque as a function of a ratio of first rear wheel speed and second rear wheel speed.

11. Electric bicycle drive system comprising: a drive arrangement (10), and a control unit (50) which is configured to carry out the method according to one of the preceding claims.

12. Electric bicycle drive system according to claim 11, wherein the drive arrangement (10) comprises a motor (1) which can be arranged on a hub of the bicycle.

13. Electric bicycle drive system according to claim 11 or 12, wherein the electric bicycle drive system or the drive arrangement (10) is designed without a torque sensor and / or bearing force sensor.

14. Bicycle, in particular an electric bicycle (100), comprising an electric bicycle drive system according to any one of claims 11 to 13.

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