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), wherein the drive assembly (10) comprises a gear shift mechanism (5), having the steps of: continuously determining (41) a first transmission ratio on the basis of a detected pedal frequency and a detected bicycle speed, providing (42) a second transmission ratio, in particular for use for functions of the drive assembly (10) and / or of the bicycle, and updating (43) the second transmission ratio with the current first transmission ratio if, at the same time: the detected bicycle speed is greater than or equal to a specified threshold value, an active driver intervention is detected, and a specified trigger signal is detected.

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] The method according to the invention, with the features of claim 1, is characterized in that it provides a particularly simple and cost-effective way to determine the gear ratio of a bicycle drive system. In particular, it enables the operation of a motor in the case of an electric bicycle in a particularly simple, reliable, and cost-effective manner. According to the invention, this is achieved by a method for operating a bicycle drive system, especially an electric bicycle, wherein the drive system includes a gearshift. The method comprises the steps of: continuously determining a first gear ratio based on a detected cadence and a detected bicycle speed; providing a second gear ratio, in particular for use in functions of the drive system and / or the bicycle; and

[0009] Updating the second translation ratio with the current first translation ratio, if simultaneously:

[0010] - the recorded bicycle speed is greater than or equal to a predetermined threshold,

[0011] - an active driver intervention is detected,

[0012] - a predetermined trigger signal is detected, and

[0013] - in particular, the riding condition of the bicycle is detected.

[0014] Preferably, the bicycle speed and / or cadence are recorded using at least one sensor. This recording can be direct or, alternatively, indirect, for example, by conversion.

[0015] Continuous determination refers in particular to the ongoing, uninterrupted determination of the first translation ratio. For example, this can be done discretely over time using a specific sampling rate.

[0016] Preferably, various software functions or the like, which influence the operation of the bicycle, can be considered functions of the drive system and / or the bicycle. For example, in the case of an electric bicycle, motor torque generation is considered a function. That is, the motor torque can be generated depending on the determined second gear ratio.

[0017] In particular, updating the second translation ratio by the current first translation ratio is understood to mean that the current value of the second translation ratio is replaced by a current value of the first translation ratio.

[0018] Preferably, the predetermined speed threshold is at least 2 km / h, preferably at least 4 km / h, and in particular a maximum of 6 km / h.

[0019] Active rider intervention is defined as any interaction between the rider and the bicycle's drivetrain that generates a propulsive torque. In other words, during active rider intervention, the rider's pedaling force at least partially generates a propulsive torque for the bicycle. Specifically, during active rider intervention, the drivetrain is tensioned by the rider's pedaling force. For example, rider intervention can be detected directly using sensors. Alternatively, and preferably, rider intervention can be determined based on measured parameters such as cadence and bicycle speed.

[0020] A trigger signal can be considered a predetermined signal, which is automatically generated, for example, in certain driving situations and / or in response to certain events.

[0021] The second gear ratio is preferably updated by the current first gear ratio when a riding state of the bicycle is detected. A riding state of the bicycle is defined, in particular, as a state in which there is no acceleration from a standstill. That is, the bicycle is moving in this riding state, especially at a predetermined minimum speed. For example, the riding state is detected when no acceleration from a standstill is observed.

[0022] In other words, the method uses two different gear ratios simultaneously at all times: a continuous first gear ratio and a global second gear ratio. The global second gear ratio is assumed to be the actual instantaneous gear ratio of the drive arrangement and is used for subsequent functions. In certain situations, when the aforementioned criteria are met, the second gear ratio is updated by the instantaneous first gear ratio. In all other situations and at all times, the currently valid second gear ratio is maintained.

[0023] This method offers the advantage of determining and providing the gear ratio of the drive system in a particularly simple, cost-effective, and reliable manner. Continuously determining the initial gear ratio can be achieved using very simple and inexpensive means. For example, simple and inexpensive sensors can be used. Furthermore, the calculation can be performed very easily and efficiently. Moreover, precise knowledge of the gear ratio enables a particularly flexible and optimized operation of the bicycle. For example, in the case of an e-bike, optimized motor operation can be provided based on the determined gear ratio. This results in a particularly high level of user comfort for the cyclist.

[0024] The dependent claims describe preferred embodiments of the invention.

[0025] Preferably, the trigger signal includes a gear change signal, which is generated in response to a detected gear change. For example, the gear change can be detected in response to an automatic actuation by a control unit, in particular by means of a gear change signal from a control unit. Alternatively or additionally preferably, the gear change can be detected in response to a shift command manually generated by the driver. Furthermore, alternatively or additionally preferably, the gear change can be determined automatically based on sensor signals. In particular, a recalculation of the gear ratio for the global second gear ratio is initiated with each detected gear change.

[0026] Preferably, the shifting process is detected based on the recorded cadence. Particularly preferably, this involves recording a cadence profile over time, determining a derivative function of the cadence profile over time, determining the crank acceleration using the determined derivative function, and detecting the shifting process when the determined crank acceleration exceeds a predetermined acceleration threshold, and simultaneously detecting a maximum in the time-dependent crank acceleration, and preferably also detecting the bicycle's riding state. This allows for software-based shift detection, which makes detecting the shifting process particularly simple and cost-effective.

[0027] Preferably, the trigger signal includes a monitoring signal, which is generated by a monitoring unit. The monitoring unit can preferably be a software function of a control unit. In particular, the monitoring unit can alternatively be referred to as a "watchdog." This allows for particularly flexible initiation of the recalculation of the global second rate ratio. Thus, a highly adaptable execution of the process is possible, enabling simple and efficient operation. Furthermore, the trigger signal can be generated with precise control to obtain highly reliable information about the current rate ratio.

[0028] The monitoring signal is preferably generated by the monitoring unit based on a comparison of the first translation ratio with the second translation ratio. That is, to update the second translation ratio, the current relative relationship between the first and second translation ratios is considered. This allows for a particularly targeted update of the second translation ratio, ensuring high accuracy.

[0029] Preferably, the monitoring unit integrates the difference between the first and second gear ratios over time and generates the monitoring signal when the result of the integration reaches or exceeds a predetermined trigger threshold. In other words, the trigger signal is generated when the cumulative difference between the first and second gear ratios exceeds a threshold over time. This provides a particularly simple and efficient way to obtain precise information about the actual instantaneous gear ratio.

[0030] Active driver intervention is particularly likely to be detected using the following steps:

[0031] Recording cadence,

[0032] Detecting an initial rear wheel speed, in particular directly by means of a speed sensor,

[0033] Determining a second rear wheel speed using the recorded cadence,

[0034] 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. Preferably, the second rear wheel speed is determined using a known rear wheel circumference. Preferably, the predetermined factor has a value less than 1, preferably greater than 0.5. This allows active rider intervention to be reliably detected using simple and cost-effective means.

[0035] Preferably, the continuous determination of the first gear ratio includes filtering the recorded cadence, preferably using a first-order low-pass filter. This smooths out fluctuations in the recorded cadence, making the further determination of the gear ratios particularly simple and precise.

[0036] Preferably, the continuous determination of the first gear ratio comprises determining the rear wheel rotational speed using the recorded bicycle speed and a known rear wheel circumference, and determining the ratio of the determined rear wheel rotational speed to the determined cadence. That is, the first gear ratio can be calculated directly using the rear wheel rotational speed, the known rear wheel circumference, and the cadence. This allows the first gear ratio to be calculated precisely and reliably at any time using simple and cost-effective means.

[0037] 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 precisely 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 rider's active input and adjusting the motor accordingly, particularly reliable and comfortable operation of the bicycle can be achieved. 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.

[0038] Preferably, the drive arrangement includes a motor. Preferably, the control unit is additionally configured for controlled actuation of the motor. The motor is 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.

[0039] 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.

[0040] Brief description of the drawings

[0041] 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:

[0042] 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.

[0043] Figure 2 is a highly simplified schematic view of the method according to the invention, Figure 3 is a highly simplified schematic detail of the method according to the invention,

[0044] Figure 4 shows a further highly simplified schematic detail of the method according to the invention.

[0045] Figure 5 shows a further highly simplified schematic detail of the method according to the invention, and

[0046] Figure 6 shows an exemplary cadence curve over time, which occurs during the

[0047] The procedure can be used to carry it out.

[0048] Embodiments of the invention

[0049] 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.

[0050] The bicycle 100 is an electric bicycle 100, which features a hub drive. Specifically, the electric bicycle 100 comprises a motor that is located on the hub of one of the rear wheels 110 of the electric bicycle 100.

[0051] 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.

[0052] 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.

[0053] A motor torque generated by the motor of the drive assembly 10 can provide motor assistance to the pedaling force generated by the rider of the electric bicycle 100. 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] When the electric bicycle 100 is in operation, the motor torque is provided depending on the pedaling force generated by the rider.

[0058] 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. Specifically, it allows for pedal-dependent operation of the motor, thereby eliminating the need for torque sensors and bearing force sensors. The electric bicycle 100 is preferably designed without torque sensors and bearing force sensors.

[0059] The inventive method 1 is described in detail below with reference to Figures 2 to 6.

[0060] Method 1 essentially comprises three main functions: an intervention detection 11, a gear 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. Figure 3 shows a highly simplified schematic detail of Method 1 of the preferred embodiment. In Figure 3, the intervention detection 11 is shown 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.

[0061] 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.

[0062] The first rear wheel rotation speed is preferably detected directly by means of a speed sensor.

[0063] The cadence is preferably recorded using a cadence sensor.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] Active rider intervention is detected when the determined second rear wheel speed is at least equal to the determined speed threshold. This means that in this case, it is recognized that the rider is actively interacting with the drivetrain and actively contributing to the propulsive torque of the e-bike by means of their pedaling force. In this method, the generation of motor torque occurs only when active rider intervention is detected. In other operating states, where no active rider intervention is detected, no motor torque is provided and / or the provision of motor torque is actively prevented.

[0068] Alternatively or additionally, preferably, the generation of motor torque 30 can be achieved depending on the ratio of the first rear wheel speed to 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.

[0069] 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.

[0070] 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.

[0071] Furthermore, detection step 20 includes detecting 29 a movement initialization 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. Figure 4 shows a further highly simplified schematic detail of method 1 of the preferred embodiment of the invention. In Figure 4, the determination of the transmission ratio 12 is shown in more detail.

[0072] In method 1, two different translation ratios are used simultaneously at all times: a continuous first translation ratio and a global second translation ratio.

[0073] The global second transmission ratio is determined in step 42 and assumed to be the actual instantaneous transmission ratio of the drive arrangement 10.

[0074] 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.

[0075] 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.

[0076] 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. Update 43 is performed when the following criteria are met simultaneously:

[0077] - the recorded bicycle speed is greater than or equal to a predetermined threshold,

[0078] - active driver intervention is detected by means of intervention detection 11 ,

[0079] - a predetermined trigger signal is detected, and in particular

[0080] - a driving condition 15 of the electric bicycle 100 is detected.

[0081] Driving condition 15 is specifically defined as a state of the electric bicycle 100 in which there is no restart from a standstill. That is, the electric bicycle 100 moves at a predetermined minimum speed.

[0082] The detection of the trigger signal is indicated by step 16 in Figure 4.

[0083] The trigger signal includes a gear change signal, which is generated in response to a detected gear change. Gear change detection is performed using function 13 of method 1, as described later.

[0084] 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.

[0085] Alternatively or additionally, preferably, the monitoring unit can generate the monitoring signal after a predetermined period of time.

[0086] The gear ratio determination 12 thus allows for a particularly simple and cost-effective way to precisely determine and provide the currently estimated actual gear ratio. The determination of the continuous first gear ratio can be carried out in a particularly simple way and without complex and expensive sensor technology.

[0087] By updating the second gear ratio actually used only according to certain criteria through the first gear ratio, a high degree of precision of the gear ratio used can be easily provided, especially since large fluctuations in the first gear ratio, which may occur, for example, due to operational reasons in certain operating situations of the electric bicycle 100, are not taken into account.

[0088] Figure 5 shows a further highly simplified schematic detail of method 1 of the preferred embodiment of the invention. In Figure 5, the switching indicator 13 is shown in a highly simplified schematic representation.

[0089] The shift detection 13 is based on the detection of jumps 81 in the temporal course of the cadence 80, as shown in simplified form in Figure 6.

[0090] 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.

[0091] 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.

[0092] The detection of a switching process occurs when the following criteria are met simultaneously:

[0093] - The measured crank acceleration exceeds a predetermined acceleration threshold,

[0094] - a maximum is detected in the time course of the determined crank acceleration, and in particular

[0095] - A driving state 15 of the electric bicycle 100 is detected. Preferably, the driving state 15 of the electric bicycle 100 can be detected, in particular analogously to the previously described function 12, 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.

[0096] Preferably, the crank acceleration is determined and provided in discrete sequential values. The maximum in the temporal progression of the crank acceleration is identified based on these discrete sequential values, particularly when an increasing value is detected in a previous epoch and a decreasing value is detected in the current epoch.

[0097] The shift detection 13 is therefore based on the detection of high, sudden 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.

[0098] 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.

[0099] 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), wherein the drive arrangement (10) comprises a gear shift (5), comprising the steps: continuously determining (41) a first gear ratio based on a detected cadence and a detected bicycle speed, Providing (42) a second transmission ratio, in particular for use in functions of the drive assembly (10) and / or the bicycle, and Updating (43) the second translation ratio by the current first translation ratio when simultaneously: - the recorded bicycle speed is greater than or equal to a predetermined threshold, - an active driver intervention is detected, and - a predetermined trigger signal is detected.

2. Method according to claim 1, wherein the updating (43) of the second translation ratio by the instantaneous first translation ratio additionally takes place when a driving state of the bicycle is detected.

3. Method according to claim 1 or 2, wherein the trigger signal comprises a gear change signal which is generated in response to a detected switching operation.

4. Method according to claim 3, wherein the switching process is detected based on the detected cadence.

5. Method according to one of the preceding claims, wherein the trigger signal comprises a monitoring signal which is generated in a controlled manner by means of a monitoring unit.

6. Method according to claim 5, wherein the monitoring signal is generated by the monitoring unit based on a comparison of the first translation ratio with the second translation ratio.

7. Method according to claim 6, wherein the monitoring unit integrates a difference between the first translation ratio and the second translation ratio over time and generates the monitoring signal when a predetermined trigger threshold is reached or exceeded.

8. Method according to one of the preceding claims, wherein the active driver intervention is detected by means of the following steps: Recording (22) the 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, Determining (25) a speed threshold by multiplying the determined first rear wheel speed by a predetermined factor, and detecting (26) the active rider intervention when the determined second rear wheel speed is at least equal to the determined speed threshold.

9. Method according to one of the preceding claims, wherein the continuous determination (41) of the first translation ratio comprises: filtering the detected cadence, in particular by means of a first-order low-pass filter.

10. A method according to any of the preceding claims, wherein the continuous determination (41) of the first transmission ratio comprises: determining a rear wheel rotational speed using the detected bicycle speed and a previously known rear wheel circumference, and Determining the ratio of the measured rear wheel speed to the measured pedaling cadence.

11. Method according to any of the preceding claims, further comprising the step of: Generating (30) a motor torque depending on the second transmission ratio, in particular wherein the motor torque is generated exclusively during the detected active driver intervention.

12. 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.

13. Electric bicycle drive system according to claim 12, wherein the drive arrangement (10) comprises a motor (1) which can be arranged on a hub of the electric bicycle (100).

14. Electric bicycle drive system according to one of claims 12 or 13, wherein the electric bicycle drive system or the drive arrangement (10) is designed without torque sensors and / or bearing force sensors.

15. Bicycle, in particular electric bicycle (100), comprising an electric bicycle drive system according to one of claims 12 to 14.

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