Method for controlling a gear speed change of a bicycle

Abstract

The invention relates to a method for controlling a gear speed change of a shiftable transmission for a bicycle, wherein: the load on the shiftable transmission during travel is monitored; a maximum load during a gear speed change is extrapolated from the time curve of the load on the shiftable transmission; an already-triggered gear speed change is terminated before a threshold value for the maximum permissible load is reached, if the extrapolated maximum load is greater than the threshold value for the maximum permissible load during the gear speed change. The bicycle comprises: a shiftable transmission, which has a plurality of gear speeds, an input shaft and an output shaft, the output shaft being designed to be drivingly connected at least indirectly to a drive wheel of the bicycle; a crankshaft with a pedal crank for introducing drive power from a bicycle rider into the shiftable transmission, the crankshaft being drivingly connected to the input shaft; means for sensing a load on the shiftable transmission and generating corresponding sensor data; and a control device which is designed to extrapolate a maximum load during the gear speed change according to the sensor data and to terminate an already-triggered gear speed change before a threshold value for the maximum permissible load during the gear speed change is reached, if the extrapolated maximum load is greater than the threshold value for the maximum permissible load during the gear speed change.

Description

[0001] Method for controlling a gear change on a bicycle

[0002] The invention relates to a method for controlling gear changes in a bicycle with a manual transmission. The invention further relates to a bicycle with a manual transmission and a control device.

[0003] Bicycles, including electric bicycles, are known to have derailleur gears, hub gears, and bottom bracket gears. A gear shift can be actuated manually or electrically, for example, wirelessly or via cable. With known gear systems, a problem arises that shifting gears under load places increased stress on the components and can produce unpleasant noises for the user. When shifting gears under load, the rider applies increased force to the pedals and thus to the gear mechanism. This problem occurs with both manual and electrically actuated systems.The electrically actuated shifting can be triggered either based on a user request, initiated via an input device on the bicycle, or based on an automatic system that controls the gear changes. Such an automatic system can, for example, be designed to maintain a predetermined cadence and trigger corresponding gear changes when the rider deviates from this cadence.

[0004] For example, DE 10 2016 225 159 A1 discloses a gearbox for a bicycle, comprising an output shaft, a gearbox that is operatively connected to a bottom bracket crankshaft and that is operatively connected or operatively connectable to the output shaft, and an electric machine that is operatively connected or operatively connectable to the output shaft. The electric machine is connected downstream of the gearbox in terms of its drive system.

[0005] Furthermore, WO 2024 / 067975 A1 discloses a method for controlling a switching operation of an electrical circuit of a bicycle, wherein the method comprises the steps of receiving a switching request signal, determining the position of a crank arm of the bicycle and actuating the switching operation depending on the determined crank arm position.

[0006] The object of the present invention is to provide an alternative method for controlling the gear changes of a bicycle gearbox, as well as a bicycle with a gearbox that enables low-wear gear changes. These objects are achieved by the features of the independent claims. Advantageous embodiments are the subject of the dependent claims, the following description, and the figures.

[0007] In the inventive method for controlling a gear change of a bicycle gearbox, the load on the gearbox is monitored during riding, a maximum load during a gear change is extrapolated from the time course of the load on the gearbox, and a gear change that has already been initiated is aborted before reaching a threshold for the maximum permissible load if the extrapolated maximum load is greater than the threshold for the maximum permissible load during the gear change.

[0008] Extrapolating a maximum load during gear changes means predicting, or approximating, a load value during the shift, based on the time-dependent load profile of the transmission immediately before or during the gear change. This prevents increased stress on the transmission, particularly the shifting components, when shifting under load.

[0009] In other words, gear changes always occur depending on the load on the transmission. This load is sensed either directly at a specific component of the transmission or at a component rigidly connected to it, or it can be calculated indirectly using other parameters. Based on the transmission load, a maximum load that can still be reached during the gear change is extrapolated. If the extrapolated maximum load exceeds the threshold for the maximum permissible load during the gear change, the initiated gear change is aborted before reaching the threshold. Specifically, the gear change is initiated by an electrical circuit. An electrical circuit is defined as one in which the actuation and thus the triggering of the shift is at least partially electrical.Actuation is achieved through electrical impulses. This actuation can be automatic, based on an automatic gear shifting mechanism, or based on a user request via an input device, such as a lever or button.

[0010] The bicycle according to the invention has a drive device comprising the gearbox, wherein the gearbox has several gears, a drive shaft and an output shaft, wherein a gear change under load is possible, wherein the output shaft is configured to be at least indirectly connected to a drive wheel of the bicycle, a crankshaft with a pedal crank for introducing a drive power from a cyclist into the gearbox, wherein the crankshaft is connected to the drive shaft, means for detecting the load on the gearbox and generating corresponding sensor data, and a control device configured to extrapolate the maximum load during the gear change, at least depending on the sensor data, and to abort an already initiated gear change before reaching the threshold for the maximum permissible load during the gear change.if the extrapolated maximum load is greater than the threshold for the maximum permissible load during gear changes.

[0011] When two elements, particularly two shafts, are connected to each other in a way that effectively drives the system, it is understood that they necessarily rotate at a proportional speed. Further elements may be arranged between the two elements, through which an indirect connection is established, or the two elements may be directly connected. In particular, the term "detection" encompasses not only direct sensing but also the indirect calculation of the respective quantity from other quantities. The term "sensor data" refers to information about detected quantities that can be processed by the control device. Specifically, the maximum load that may be applied to the transmission during a gear change to ensure low wear is continuously extrapolated while driving.Therefore, the value for the extrapolated maximum load during gear changes varies depending on the bicycle's operation. For example, the extrapolated maximum load may increase if the load on the gearbox increases during the monitoring period, such as when the user applies more torque. Conversely, the extrapolated maximum load may decrease if less torque is applied during the monitoring period. The value of the extrapolated maximum load may remain essentially unchanged if the torque applied to the gearbox remains essentially constant during the monitoring period.

[0012] Preferably, the threshold for the maximum permissible load of the transmission during gear changes is stored in a data memory of the control unit. To determine whether the extrapolated maximum load is greater than the threshold for the maximum permissible load during gear changes, the extrapolated maximum load is continuously compared with the maximum permissible load during gear changes. As soon as the extrapolated maximum load exceeds the threshold for the maximum permissible load during gear changes, the already initiated gear change is aborted before the threshold for the maximum permissible load is reached. Additionally, a further threshold for the load on the transmission during gear changes can be stored in the control unit's data memory as an abort condition, with this further threshold being lower than the threshold for the maximum permissible load.In particular, this additional threshold can be set and changed by the bicycle user. Furthermore, the user can also change the threshold for the maximum permissible load during gear changes to make gear changes even less prone to wear or to allow more gear shifts. Preferably, the control unit has input means for receiving user input. The lower the value chosen for the maximum permissible load during gear changes, the lower the load on the gearbox during gear changes, allowing more gear shifts to be aborted. The gear change always occurs from an actual gear to a target gear and results in a change in the gear ratio between the input shaft and the output shaft of the gearbox. If a gear change is aborted, no change in the gear ratio occurs, as the gear change is not completed and the actual gear remains.

[0013] The commencement of a gear change is understood to mean that a shift request signal, either based on a control signal for automatic gear shifting or based on a shift request from a user received by an input device, sets a shift drum of a transmission's shift mechanism into rotation. The shift drum is configured to actuate pawls, thereby shifting gear pairs and changing the gear ratio. The shift drum has actuating cams and is rotated during the shifting process by an electric motor, in particular a servo motor.

[0014] A gear change is complete when all pawls to be disengaged are disengaged and all pawls to be engaged are engaged, because the gear ratio change is then complete. Monitoring the load on the transmission serves, in particular, to protect the pawls during gear changes, especially the pawls to be engaged. When a gear change is initiated, at least the shift drum is set in rotation, and pawls to be disengaged may be at least partially disengaged.

[0015] If a gear change is interrupted, the electric motor is either actively braked or continues to operate without load, for example by means of an active short circuit. In both cases, the shift drum comes to a stop. Furthermore, it is conceivable that a self-locking transmission, in particular a worm gear, is arranged between the electric motor and the shift drum.

[0016] According to a preferred embodiment, after an aborted gear change, the gear change is restarted, with the load on the transmission being monitored during the restarted gear change. A maximum load during the gear change is extrapolated from the time-dependent load on the transmission. The restarted gear change is aborted before reaching a threshold for the maximum permissible load if the extrapolated maximum load is greater than the threshold for the maximum permissible load during the gear change. Specifically, these process steps are carried out until the gear change is completed. In other words, after an aborted gear change, the gear change is restarted repeatedly until the extrapolated maximum load is less than the threshold for the maximum permissible load during the gear change, allowing the gear change to be completed.In particular, the user can be shown via display means that a gear change has not taken place due to excessive load on the transmission, especially the shifting mechanism, so that he can actively influence the load on the transmission.

[0017] Preferably, the maximum load during gear changes is extrapolated from the time-dependent load profile of the transmission during the gear change. Therefore, only loads on the transmission during gear changes, i.e., from the moment a gear change is requested, are considered for the extrapolation.

[0018] For example, the temporal profile of a torque and / or a change in torque at the drive shaft of the transmission and / or at the crankshaft of the bicycle is monitored. Preferably, a first sensor is provided for detecting a torque and / or a change in torque at the crankshaft and / or at the drive shaft. A change in torque is understood to be the gradient of the torque at a specific time. The change in torque is thus the first time derivative of the torque. In particular, the at least one first sensor is designed as a strain gauge and is arranged on the crankshaft and / or at the drive shaft. For example, the crankshaft is integrally connected to the drive shaft.

[0019] Alternatively or additionally, the crank arm position and / or changes in crank arm position are monitored over time. In particular, the crank arm position can be used to verify the torque applied by the user to the gearbox. Preferably, a second sensor is provided to detect the crank arm position and / or changes in crank arm position. From the crank arm position and / or changes in crank arm position, a crank arm torque can be approximated. A change in crank arm position is understood to be the gradient of the crank arm position at a specific time. In particular, the second sensor can be arranged either directly on the crankshaft or on an element that is rotationally fixed to the crankshaft. A "rotationally fixed connection" means that two elements rotate at the same speed.

[0020] For example, the second sensor is designed as a rotation angle sensor and configured to detect the crank angle in the range of 0 degrees to 360 degrees, which corresponds to one full revolution of the crank. Specifically, the rotation angle sensor is also configured to detect the crankshaft speed via a time reference. Thus, the crankshaft revolutions per minute are detected. Alternatively, the crank angle can be calculated using other means of detecting the crank angle. For example, the crank angle, and therefore also the crankshaft speed, can be calculated from the torque curve of the crankshaft, where the torque curve essentially corresponds to a sine function with its peaks at 90 degrees and 270 degrees, and its troughs at 0 degrees, 360 degrees, and 180 degrees.This is because the cyclist has the greatest leverage to apply their pedaling force to the pedals at crank angles of 90 degrees and 270 degrees. Conversely, the leverage is minimal at crank angles of 0 degrees, 360 degrees, and 180 degrees, which are defined as the dead centers of the crank arm. At crank angles of 90 degrees and 270 degrees, the crank arms are horizontally aligned. At crank angles of 0 degrees, 360 degrees, and 180 degrees, the crank arms are vertically aligned.

[0021] According to a preferred embodiment, the bicycle further comprises an electric machine with a rotor shaft, wherein the rotor shaft is configured to transmit drive power from the electric machine to the transmission and is, for this purpose, at least indirectly operatively connected or operatively connectable to the output shaft. For example, a freewheel can be arranged in the power flow between the rotor shaft and the output shaft. The output shaft is configured to be operatively connected to a drive wheel of the bicycle via a traction drive. Thus, the bicycle includes not only the usual components of a muscle-powered bicycle, but also the electric machine and an electrical energy storage device. Such bicycles are known as electric bicycles, e-bikes, or pedelecs. The electric drive can reduce the effort required by the cyclist during travel or increase their range.

[0022] The cyclist transmits drive power, i.e., drive speed and drive torque, to the crankshaft via the pedals. The crankshaft is operatively connected to the output shaft via the gearbox. The electric machine has a housing-mounted stator and a rotor non-rotatably connected to the rotor shaft. A further drive power, i.e., another drive speed and another drive torque, is transmitted to the gearbox via the rotor shaft. A freewheel is preferably arranged in the power flow between the rotor shaft and the output shaft to couple and decouple the rotor shaft from the output shaft. The freewheel between the output shaft and the rotor shaft decouples the output shaft from the rotor shaft as soon as the rotor shaft speed is lower than the output shaft speed.This prevents, for example, the cyclist from dragging the rotor shaft along when the electric motor is switched off. The drive power from the cyclist and the drive power from the electric motor are superimposed, and this drive power is transmitted to the bicycle's drive wheel via the output shaft and the traction drive.

[0023] In particular, the gearbox has several gear pairs, with a shifting mechanism comprising an actuator and a shift drum. The shifting mechanism allows the respective gear pairs to be switched in such a way that the gears, and thus the gear ratios between the input shaft and the output shaft, are set. Control commands are transmitted from the control unit to the gearbox's shifting mechanism to adjust or change the gear ratio, enabling, for example, automated operation. Alternatively or additionally, the gear ratio can be changed manually by the cyclist using appropriate input devices.

[0024] Exemplary embodiments of the invention are explained in more detail below with reference to the schematic drawings, where identical elements are designated with the same reference numeral. Here, [the following is shown]

[0025] Fig. 1 shows a highly simplified schematic representation of a bicycle according to the invention with a gearbox and a control device,

[0026] Fig. 2 shows a block diagram of a method according to the invention and

[0027] Fig. 3 shows a block diagram of several components of the bicycle according to Fig. 1.

[0028] Figure 1 shows a highly simplified representation of a bicycle 100 according to the invention. The bicycle 100 has a frame 104 on which a front wheel 103, a rear wheel designed as a drive wheel 102, handlebars 105, and a saddle 108 are arranged. Furthermore, the bicycle 100 has a drive device 1, which is configured to propel the bicycle 100 at least with the muscle power of a cyclist (not shown here). For this purpose, the cyclist sits, for example, on the saddle 108 while riding and applies drive power to a gearbox 2 of the drive device 1 via pedals 109, which are connected to the drive device 1 via cranks. The cranks are connected to a drive shaft 4 of the gearbox 2 via a crankshaft 5 in a rotationally fixed manner, the crankshaft 5 and the drive shaft 4 being shown only in Figure 3.In particular, the crankshaft 5 and the drive shaft 4 can be formed as a single unit.

[0029] The drive device 1 also includes an electric machine 6, which is configured to introduce auxiliary drive power into the gearbox 2 to assist the cyclist. The drive powers of the electric machine 7 and the cyclist are superimposed and transmitted via an output shaft 3, shown only in Fig. 3, to the drive wheel 102 of the bicycle 100. For example, the electric machine 6 can be integrated into the gearbox 2. The output shaft 3 is effectively connected to the drive wheel 102, for example, via a first chainring, which is rotationally fixed to the output shaft 3, a second chainring, which is rotationally fixed to the drive wheel 102, and a chain arranged between them. Thus, the two chainrings and the chain form a traction drive 101 designed as a chain drive, which is shown in Fig. 1.Alternatively, the use of a belt drive is also conceivable to transmit drive power from the drive device 1 to the drive wheel 102 of the bicycle 100.

[0030] Furthermore, input devices 106 are arranged on the bicycle handlebars 105, which the cyclist can use to initiate a gear change in the gearbox 2. A gear change alters the gear ratio in the gearbox 2. The bicycle 100 also has a control unit 10 and means for detecting a load on the gearbox 2 and generating corresponding sensor data for the control unit 10. These means for detecting a load on the gearbox 2 comprise a first sensor 11 and a second sensor 12, which are shown only in Fig. 3.The control unit 10 is designed to extrapolate a maximum load during gear changes, at least depending on the sensor data, and to abort a gear change that has already been initiated before reaching a threshold for the maximum permissible load during gear changes if the extrapolated maximum load is greater than the threshold for the maximum permissible load during gear changes.

[0031] In Fig. 2, the inventive method for controlling the gear change of the transmission 2 for the bicycle 100 shown in Fig. 1 is shown as a block diagram.

[0032] According to process step S1, the load on the transmission 2 during driving is monitored by the control unit 10. For this purpose, the control unit 10 is connected to the first sensor 11 via signal transmission. This sensor detects the time course of a torque on the drive shaft 4 of the transmission 2 and generates sensor data for the control unit 10. The first sensor 11 is, for example, designed as a strain gauge and is arranged on the drive shaft 4. The second sensor 12, which is provided alternatively or additionally, is arranged on the crankshaft 5 to detect the pedal crank position and is intended to generate sensor data on the time course of the pedal crank position for the control unit 10.From the pedal crank position and other operating data of the bicycle 100, the control unit 10 can at least indirectly determine a load on the gearbox 2 or use the pedal crank position to verify the plausibility of the sensor data of the first sensor 1 1.

[0033] According to process step S2, a gear change is initiated, for example, by the user or by an automated shifting device. The control unit 10 extrapolates a maximum load during the gear change from the time course of the load on the transmission 2 during the gear change, i.e., from the time the gear change is initiated, and compares this extrapolated maximum load with a threshold value for the maximum permissible load during the gear change stored on the control unit 10.

[0034] If the extrapolated maximum load is less than the threshold for the maximum permissible load during the gear change, the triggered gear change is carried out according to procedure step S3 and a change in the gear ratio is achieved.

[0035] However, if the extrapolated maximum load exceeds the threshold for the maximum permissible load during gear changes, the already initiated gear change is aborted before reaching the threshold for the maximum permissible load, according to procedure step S4. This prevents increased stress on the transmission 2, particularly the shifting components, during shifting under load.

[0036] According to procedure step S5, the gear change is restarted after the aborted gear change, with the load on the transmission 2 being monitored during the restarted gear change. The control unit 10 extrapolates a maximum load during the gear change from the time-dependent load profile of the transmission 2 during the restarted gear change and compares this extrapolated maximum load with a threshold value for the maximum permissible load during the gear change stored on the control unit 10.

[0037] If the extrapolated maximum load is less than the threshold for the maximum permissible load during the gear change, the retriggered gear change is carried out according to procedure step S6 and a change in the gear ratio is achieved.

[0038] However, if the extrapolated maximum load is greater than the threshold for the maximum permissible load during the re-initiated gear change, the already triggered gear change is aborted before the threshold for the maximum permissible load is reached, according to process step S7. Specifically, process step S5 is executed until the gear change has been completed. In other words, after an aborted gear change, the gear change is re-initiated repeatedly until the extrapolated maximum load is less than the threshold for the maximum permissible load during the gear change, allowing the gear change to be completed.

[0039] Figure 3 shows a highly simplified section of the interacting components of the bicycle. The control unit 10 is connected to the input devices 106, the gearbox 2, and the first and second sensors 11, 12 via signal transmission. For example, the signal transmission connection can be wired, wireless, or optical. A signal transmission connection is a communication link in which data, especially measurement data, and / or information are transmitted as a signal from a sender to a receiver. The signals can be, for example, switching, control, data transmission, or command signals. In this case, the input devices 106 are also connected to the gearbox 2 via signal transmission to initiate gear changes at the cyclist's request. This direct connection can also be omitted, in which case the gear change is transmitted indirectly to the gearbox 2 via the control unit 10.The first sensor 11 detects a torque on the drive shaft 4 and transmits this sensor data to the control unit 10 for evaluation. The second sensor 12 detects a pedal crank position on the crankshaft 5 and transmits this sensor data to the control unit 10 for evaluation. The control unit 10 carries out the procedure according to Fig. 2.

[0040] Reference mark

[0041] drive device

[0042] Gearbox output shaft drive shaft crankshaft electric machine control unit first sensor second sensor third sensor bicycle traction drive drive wheel

[0043] Front wheel, frame, bicycle handlebars, input device, saddle, pedals, process step, process step, process step, process step, process step, process step

[0044] Procedure step

Claims

Patent claims 1. Method for controlling a gear change of a manual transmission (2) for a bicycle (100), wherein the load on the manual transmission (2) is monitored during driving, wherein a maximum load during a gear change is extrapolated from the time course of the load on the manual transmission (2), wherein a gear change that has already been initiated is aborted before reaching a threshold for the maximum permissible load if the extrapolated maximum load is greater than the threshold for the maximum permissible load during the gear change.

2. Method according to claim 1, wherein the gear change is restarted after an aborted gear change, wherein the load on the transmission (2) is monitored during the restarted gear change, wherein a maximum load during the gear change is extrapolated from the time course of the load on the transmission (2), wherein the restarted gear change is aborted before reaching a threshold for the maximum permissible load if the extrapolated maximum load is greater than the threshold for the maximum permissible load during the gear change.

3. Method according to claim 1 or 2, wherein the maximum load during gear change is extrapolated from the time course of the load on the transmission (2) during gear change.

4. Method according to one of the preceding claims, wherein a time course of a torque and / or a change in torque on a drive shaft (4) of the gearbox (2) and / or on a crankshaft (5) of the bicycle (100) is monitored.

5. Method according to one of the preceding claims, wherein a time course of a pedal crank position and / or a change in the pedal crank position is monitored.

6. Control device (10) configured to perform a procedure according to any of the preceding claims.

7. Bicycle (100) comprising a drive device (1) • a multi-gear transmission (2), a drive shaft (4) and an output shaft (3), wherein a gear change is possible under load, wherein the output shaft (3) is arranged to be connected, at least indirectly, to a drive wheel (102) of the bicycle (100) in a driving manner, • a crankshaft (5) with pedal cranks for transmitting drive power from a cyclist to the gearbox (2), wherein the crankshaft (5) is effectively connected to the drive shaft (4), • Means for detecting a load on the manual transmission (2) and generating corresponding sensor data, and • a control device (10) designed to extrapolate a maximum load during gear changes, at least as a function of these sensor data, and to abort a gear change that has already been initiated before reaching a threshold for the maximum permissible load during gear changes if the extrapolated maximum load is greater than the threshold for the maximum permissible load during gear changes.

8. Bicycle (100) according to claim 7, wherein a first sensor (1 1 ) is provided for detecting a torque and / or a change in torque on the crankshaft (5) and / or on the drive shaft (4).

9. Bicycle (100) according to claim 7 or 8, wherein a second sensor (12) is provided for detecting a pedal crank position and / or a change in the pedal crank position.

10. Bicycle (100) according to one of claims 7 to 9, further comprising an electric machine (7) for introducing an auxiliary drive power into the gearbox (2).

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