Method for operating a drive assembly of an electric bicycle

Abstract

The invention relates to a method (20) for operating a drive assembly (10) of an electric bicycle (100), comprising the following steps: detecting (21) a pedal frequency of a crank drive (104); detecting (22) a rear wheel rotational speed of a rear wheel (110); determining (23) a transmission ratio between the crank drive (104) and the rear wheel (110); determining (24) an intervention ratio (31) on the basis of the pedal frequency and the rear wheel rotational speed and the transmission ratio; generating (25) a motor torque as a function of the determined intervention ratio (31).

Description

Technical Field

[0001] The present invention relates to a method for operating a drive assembly for an electric bicycle, a drive assembly for an electric bicycle, and an electric bicycle. Background Technology

[0002] Electric bicycles are known to have a drive unit that generates motor torque to support the rider's pedaling force. Typically, the generation of motor torque is correlated with the rider's pedaling force. This is usually achieved by directly detecting the pedaling torque generated by the rider, for example, using a torque sensor. However, this approach often requires a complex and costly structure for the electric bicycle's drive components. Summary of the Invention

[0003] In contrast, the method according to the invention, which possesses the features of the present invention, is characterized by its ability to provide motor support for an electric bicycle in a particularly simple and cost-effective manner. In particular, a particularly simple and cost-effective structure for the drive assembly of the electric bicycle can be achieved here. According to the invention, this is achieved by a method for operating the drive assembly of an electric bicycle, the method comprising the following steps: - Detect the cadence of the crank drive; - Detect the rear wheel speed; - Determine the transmission ratio between the crank drive and the rear wheel; - Calculate the engagement ratio based on the cadence, rear wheel speed, and gear ratio; and - Based on the determined intervention ratio, motor torque is generated.

[0004] The gear ratio specifically refers to the gear ratio of the mechanical torque transmission path between the crankshaft and the rear wheel. For example, in the case of a direct torque transmission connection (i.e., especially when the torque transmission path is fully engaged or force-locked), the gear ratio is equivalent to the ratio of cadence to rear wheel speed.

[0005] The intervention ratio specifically refers to the predetermined coefficient described below, which is determined solely based on parameters such as cadence, rear wheel speed, and gear ratio. Preferably, the intervention ratio is equivalent to the ratio of the detected rear wheel speed to the cadence multiplied by the gear ratio. Particularly preferably, the intervention ratio k is determined based on the following formula: Where i is the gear ratio, ω hr ω is the rear wheel speed. k This refers to cadence.

[0006] Preferably, the motor torque is generated based on the determined intervention ratio, so that a higher intervention ratio produces a larger motor torque, and a lower intervention ratio produces a smaller motor torque.

[0007] In other words, this method requires simultaneous detection of cadence and rear wheel speed, preferably during the forward motion of the electric bicycle. Simultaneously, the real-time transmission ratio between the crankshaft and the rear wheel is also detected. Based on the parameters obtained above, the real-time engagement ratio of the electric bicycle's transmission system is calculated. The generation of motor torque (especially via the drive unit of the electric bicycle's drive assembly) is then based on the calculated engagement ratio.

[0008] Therefore, the advantage of this method lies in its ability to reliably and controllably generate motor torque in a particularly simple and cost-effective manner based on particularly simple detection feasibility. Simple and cost-effective sensors (such as speed sensors) can be used here. In particular, torque sensors can be eliminated. Furthermore, the calculation of the target motor torque is performed in a particularly simple and time-efficient manner. Moreover, by considering the real-time actual state of the transmission system under pedal operation, drive control optimally matched to the rider's pedaling habits can be provided. Thus, high riding comfort can be achieved, for example, for riders of electric bicycles.

[0009] The specification contains preferred extensions of the invention.

[0010] Preferably, the method further includes the step of identifying active rider intervention when the obtained intervention ratio corresponds to at least one predetermined intervention threshold. Motor torque generation is performed based on the identified active rider intervention. Specifically, active rider intervention refers to the interaction between the rider of the e-bike and the drivetrain of the e-bike that generates traction torque. That is, when active rider intervention occurs, the rider's pedaling force is at least partially converted into the drive torque of the e-bike. In other words, during active rider intervention, the drivetrain is tensioned by the rider's pedaling force. Particularly preferably, the intervention threshold is at least 0.85, preferably at least 0.9, more preferably at least 0.95, and especially at most 1.1. Preferably, the controlled generation of motor torque is performed based on active rider intervention, specifically by providing a specific target motor torque as the motor torque only when active rider intervention is identified. That is, the desired target motor torque (e.g., preset based on different support modes of the e-bike) is provided only during the period when active rider intervention is identified. Therefore, it is possible to provide electric bicycles with particularly targeted operation in a simple and cost-effective manner, with a high degree of user comfort.

[0011] Particularly preferably, a characteristic curve is defined, which defines a target motor support based on the intervention ratio. Motor torque generation is based on this characteristic curve. That is, the characteristic curve defines exactly one target motor support value for each possible intervention ratio, and the motor torque is adjusted according to this target motor support value during controllable generation. Preferably, the characteristic curve is precisely defined in advance and, for example, stored. Alternatively, the characteristic curve is preferably adaptably constructed, for example, based on different riding parameters. With the aid of this characteristic curve, the operation of the electric bicycle can be carried out in a particularly simple and cost-effective manner, wherein optimized motor torque delivery can be achieved for high riding comfort.

[0012] Preferably, the characteristic curve defines an intervention region in which the intervention ratio is 1. Specifically, the intervention region corresponds to a portion of the characteristic curve that extends within a defined intervention ratio range. In particular, the value 1 is centrally located within the intervention ratio range. This intervention region here defines predetermined intervention motor support as target motor support. Preferably, the intervention motor support corresponds to the output torque of the ride regulator, or alternatively, to a predetermined defined motor torque with a defined value, or alternatively, to a coefficient 1 multiplied by the output ride regulator torque. Preferably, the intervention region extends within an intervention ratio range of at least 0.85, preferably at least 0.9, especially at least 0.95, to a maximum of 1.2, preferably a maximum of 1.15, especially a maximum of 1.1, and particularly preferably a maximum of 1.05. In other words, the characteristic curve is defined by the intervention region, which essentially represents the identified active rider intervention, thereby providing the full preset motor torque. This motor torque can be generated, for example, based on the output of the ride regulator, which can provide a defined motor torque according to a selected support mode. This allows for a highly targeted and simple approach, enabling the generation of preset motor torque only when the active rider intervenes.

[0013] More preferably, the characteristic curve has an enhanced region corresponding to an intervention ratio greater than 1, particularly greater than or equal to 1.05. This enhanced region defines enhanced motor support as target motor support, which is greater than the intervention motor support. Specifically, the enhanced motor support corresponds to the maximum motor support that the drive assembly can provide. That is, within the enhanced region, the maximum possible motor torque of the drive unit generating the drive assembly is taken as the motor torque.

[0014] Preferably, the enhancement region has at least one linear region and a constant region, wherein the linear region is arranged between the constant region and the intervention region. Within the linear region, motor support is linearly increased according to the intervention ratio, particularly until enhanced motor support is reached in the constant region. This allows for a continuous increase in motor torque at a higher intervention ratio than in the intervention region.

[0015] In particular, the enhanced region provides a short-term boost to the maximum support for the drive components. This allows for acceleration processes with, for example, exceptionally high acceleration for a short period. For instance, when extension and elongation occur in drivetrain components due to the rider's large and intense pedaling torque, an excessively high intervention ratio may occur, for example, compared to when the rider actively intervenes. That is, for example, the bicycle chain extends due to the rider's extremely intense pedaling, resulting in an intervention ratio exceeding 1 or 1.05. Alternatively, an increased intervention ratio occurs due to faster and more accurate signal detection at the crank relative to the rear wheel. By providing the maximum possible motor torque in these scenarios, exceptionally high riding comfort for the rider can be provided through high support in these situations.

[0016] Preferably, the characteristic curve further defines an idle region corresponding to an engagement ratio of less than 0.8, particularly less than 0.5. This idle region limits the target motor support to zero. Specifically, the following region is considered an idle region: in which the rider of the e-bike is not pedaling at all, or is pedaling without pedaling (i.e., the cadence is significantly lower than the engagement cadence). Within the idle region, the drive unit does not generate any motor torque. Thus, it can be reliably ensured in a simple manner that no motor torque is generated when pedaling without pedaling or when there is no pedaling at all.

[0017] More preferably, the characteristic curve further defines a ramp region located between the idling region and the intervention region. This ramp region defines a continuous increase in target motor support based on the determined intervention ratio. That is, when the intervention ratio is within the ramp region, a small motor support with a motor torque lower than the predetermined intervention motor support of the intervention region is achieved. This allows for a continuous progression of target motor support from zero to intervention motor support. Consequently, sudden intervention of motor support is avoided, instead providing a gentle intervention at the imminent full-initiated rider intervention. Similarly, in the reverse direction, motor support gradually and continuously decreases to zero at the imminent end of the active rider intervention (i.e., a decrease in the intervention ratio). This results in exceptionally high riding comfort for the e-bike rider.

[0018] Particularly preferably, the ramp region has at least two sub-regions, each with a different slope for a continuous increase supported by the target motor. That is, the gradient of the characteristic curve is different in at least two sub-regions of the ramp region. Preferably, the first sub-region corresponds to a smaller intervention ratio, and the gradient in the first sub-region is smaller than the gradient in the second sub-region (which corresponds to a larger intervention ratio). Particularly preferably, the characteristic curve is constructed as a straight line in each of the two sub-regions. Alternatively, preferably, the characteristic curve can be configured as any mathematical function. This enables a slow increase in motor torque at lower intervention ratios within the ramp region, followed by a faster increase in motor torque as the rider approaches a larger intervention ratio. In particular, this avoids or reduces "glide," in which the rider pedals with a low cadence and no intervention while generating relatively high motor torque. Furthermore, it provides a reliable and rapid start-up of motor support when active rider intervention is imminent.

[0019] Preferably, the method further includes the step of scaling the characteristic curve according to different support modes of the electric bicycle (preferably manually operable support modes). This scaling specifically refers to taking into account variations in the characteristic curve due to different levels of motor support. For example, the characteristic curve can be translated along the axis of motor support for different support modes. Alternatively or additionally, it is preferable to translate, stretch, or compress regions with different intervention ratios. This allows for different configurations of the degree of support by the drive unit, particularly in different support modes.

[0020] Preferably, the gear ratio is determined based on signals from the shifting system. In particular, if the shifting system includes electronic shifting, the gear ratio can be provided directly by the shifting system, for example, as a signal. Alternatively or additionally, preferably, the gear ratio is determined based on detected crank drive cadence and detected rear wheel speed, preferably when active rider intervention is detected. That is, the real-time gear ratio can be calculated in these situations when active rider intervention occurs. For example, the gear ratio can be retained based on the calculation and preferably recalculated subsequently in specific scenarios (such as gear changes). Alternatively or additionally, the gear ratio can be automatically recalculated at regular intervals. Thus, the gear ratio can be determined in a flexible and efficient manner, and the intervention ratio can be calculated based on this gear ratio.

[0021] Preferably, the cadence of the crankshaft is detected using a higher time sampling rate than that used for detecting the rear wheel speed. In other words, the cadence sensor has a higher time sampling rate than the rear wheel speed sensor. This allows for particularly accurate and reliable detection of the parameters used to execute the method. In particular, it enables reliable and accurate identification of rider intervention. Furthermore, it allows for the precise determination of extremely high cadence increases with respect to rear wheel speed, which would result in an intervention ratio greater than 1, thus falling into the enhancement region.

[0022] Furthermore, the present invention also provides a drive assembly for an electric bicycle, comprising a control unit configured to perform the aforementioned method. In particular, the drive assembly further comprises a drive unit, wherein the control unit is additionally configured to controllably manipulate the drive unit to generate motor torque.

[0023] Furthermore, the present invention provides an electric bicycle that includes the aforementioned drive assembly.

[0024] Preferably, the electric bicycle or drive assembly is constructed without torque sensors and / or bearing force sensors. That is, specifically, there are no torque sensors and / or bearing force sensors for detecting pedal operation. This allows for a particularly simple and cost-effective construction of the electric bicycle or drive assembly. Attached Figure Description

[0025] The present invention will now be described with reference to embodiments and accompanying drawings. In the drawings, components with the same function are labeled with the same reference numerals. As shown here: Figure 1 A simplified schematic view of an electric bicycle in which the method described according to a preferred embodiment of the present invention is performed; Figure 2 A highly simplified schematic view according to the method of the present invention; Figure 3 A highly simplified schematic view of an exemplary feature curve used in the method according to the present invention. Detailed Implementation

[0026] Preferably, the same components, elements and / or units in all the figures are given the same reference numerals.

[0027] Figure 1 This is a simplified schematic diagram of an electric bicycle 100, which has a drive assembly 10, in which a method 20 for operating the drive assembly 100 according to a preferred embodiment of the present invention is performed.

[0028] The drive assembly 10 of the electric bicycle 100 includes a drive unit 105 having a motor, particularly an electric motor. The motor can be powered by an energy storage device 109 of the electric bicycle 100.

[0029] The drive unit 105 is a hub drive unit and is located at the rear hub of the rear wheel 110 of the electric bicycle 100.

[0030] In another alternative (not shown) embodiment, an electric bicycle 100 with a mid-mounted motor may also be involved, wherein the drive unit 105 is arranged in the area of ​​the pedal axle.

[0031] The motor torque generated by the motor in the drive unit 105 provides motor-driven support for the pedaling force generated by the rider's muscle strength in the electric bicycle 100. The rider's muscle strength can be applied here via a crank transmission 104 with a crank.

[0032] The drive assembly 10 also includes a control unit 50 configured to controllably operate the drive unit 105. For example, the control unit 50 can control the operating current of the motor used to operate the drive unit 105.

[0033] In the illustrated embodiment, the control unit 50 is exemplaryly arranged at the energy storage device 109. Alternatively, the control unit 50 may also be arranged at any other location on the electric bicycle 100.

[0034] The pedaling torque applied by the rider to the crank drive 104 can be transmitted to the rear wheel hub of the rear wheel 110 via the transmission element 107 (e.g., preferably a bicycle chain).

[0035] Preferably, a transmission is arranged between the motor of the drive unit 105 and the rear wheel hub, and the transmission is part of the drive unit 105.

[0036] Furthermore, the electric bicycle 100 includes a shifting system 106, by means of which a variety of different gear ratios can be provided. The shifting system 106 can be operated, for example, manually by the rider, and / or automatically by the control unit 50 to provide different gear ratios.

[0037] The method 20 enables the drive unit 105 to be controllably manipulated based on the rider's pedal operation, without using a pedal force sensor or pedal torque sensor.

[0038] The control unit 50 is also configured to perform the method 20.

[0039] In method 20, the cadence of crank transmission 104 is detected; and the rear wheel speed of rear wheel 110 is detected simultaneously.

[0040] In addition, the real-time transmission ratio between crank transmission 104 and rear wheel 110 is calculated simultaneously.

[0041] Preferably, the determination of the transmission ratio 23 is based on the real-time transmission ratio provided and is achieved by a determination unit, which in turn determines the transmission ratio in real time. Figure 2 In step 27, the gear ratio is determined and provided. An exemplary method for determining the gear ratio is described in detail below.

[0042] Based on the detected cadence and the detected rear wheel speed, and the calculated gear ratio, the intervention ratio 31 is then calculated as 24.

[0043] Based on the obtained intervention ratio 31, the motor torque 25 is then generated by means of the drive unit 105.

[0044] Preferably, when the intervention ratio 31 obtained in step 24 corresponds to at least one predetermined intervention threshold 34 (see...) Figure 3 The method can also selectively identify 26 active rider intervention. Preferably, in this case, the generation of motor torque 25 is performed, alternatively or additionally, based on the active rider intervention identified in step 26.

[0045] In method 20, the generation 25 of motor torque is based on characteristic curve 33, as described below. Figure 3 To elaborate.

[0046] Figure 3 A simplified schematic view of Figure 30 is shown, in which an exemplary feature curve 33 is illustrated.

[0047] The characteristic curve 33 defines the target motor support 32 based on the intervention ratio 31.

[0048] Preferably, a predetermined coefficient is obtained as the target motor support 32, which is multiplied by the ride regulator torque (especially the ride regulator output torque of an electric bicycle). Preferably, the ride controller torque is equivalent to a constant torque value, which is particularly lower than the technical maximum torque of the drive unit 105.

[0049] The characteristic curve 33 here has four different regions 33a, 33b, 33c, and 33d.

[0050] The intervention region 33a of the characteristic curve 33 extends from a predetermined intervention threshold 34 (preferably 0.95) to an upper intervention threshold 34a (preferably 1.05). Within the intervention region 33a, the characteristic curve 33 defines a predetermined intervention motor support 32a as the target motor support 32.

[0051] In the intervention area 33a, the output coefficient 1 is preferably used as the intervention motor support 32a.

[0052] Furthermore, characteristic curve 33 defines an enhanced region 33b, the intervention ratio 31 of which is higher than that of intervention region 33a. Such an excessively high intervention ratio 31 may occur, for example, in the following scenario: the rider of the electric bicycle 100 pedals vigorously, causing extension in the transmission system (especially in the transmission elements), which results in a higher cadence relative to the rear wheel speed (taking the transmission ratio into account).

[0053] Within the enhanced region 33b, the target motor support 32 initially increases linearly with the intervention ratio 31 until it reaches a maximum value, which corresponds to the enhanced motor support 32b. Preferably, the enhanced motor support 32b corresponds to the maximum motor torque of the drive unit 105. Thus, the rider's extremely strong pedaling can be identified as a demand for maximum motor support, and a high motor torque is generated accordingly.

[0054] Furthermore, characteristic curve 33 defines the following idle region 33c, which corresponds to the minimum engagement ratio range, specifically the maximum idle engagement ratio 31a from zero to 0.5. The idle region 33c limits the target motor support 32 to zero. That is, within the idle region 33c, it is determined that the rider is not pedaling or is pedaling in the air. Within this region, there should be absolutely no motor support through the drive unit.

[0055] Furthermore, characteristic curve 33 defines a ramp region 33d located between the idle region 33c and the intervention region 33a. Within the ramp region 33d, the target motor support 32 is continuously raised from zero to a predetermined intervention motor support 32a according to the determined intervention ratio 31.

[0056] The slope region 33d includes a first sub-region 33e and a second sub-region 33f. Here, the first sub-region 33e, corresponding to a smaller intervention ratio 31, has a smaller slope of the characteristic curve 33 than the second sub-region 33f.

[0057] In particular, the transition point between the first sub-region 33e and the second sub-region 33f corresponds to a slope intervention ratio 31b (which is preferably 0.8).

[0058] The slope of the characteristic curve 33 in the first sub-region 33e is preferably less than 1, and especially in the second sub-region 33f, the slope is preferably greater than 1.

[0059] The slope region 33d here achieves a continuous and average operation of motor support between the regions of "complete no motor support" and "full motor support". This provides a gentle intervention of motor support, thereby providing the rider of the electric bicycle 100 with a natural riding experience and thus offering a particularly high level of riding comfort.

[0060] In execution method 20, the determination 23 of the gear ratio can preferably be based on the signal of the shift system 106 of the electric bicycle 100, which is particularly suitable for scenarios where the shift system 106 has electronic gear shifting. In this case, for example, the shift system 106 can provide the real-time gear ratio directly as a value based on the known characteristics of the shift system 106 and the transmission system of the electric bicycle 100.

[0061] Alternatively, the gear ratio can be calculated automatically. Here, the gear ratio can be calculated based on the detected cadence of the crank drive 104 and the rear wheel speed of the rear wheel 110 during the period when active rider intervention is detected.

[0062] When no active rider intervention is detected, the gear ratio can be assumed to remain constant, for example, and recalculated the gear ratio the next time rider intervention is detected.

[0063] Before the first detection of active rider intervention, a predetermined exemplary gear ratio may be assumed, for example.

Claims

1. A method for operating a drive assembly (10) of an electric bicycle (100), comprising the steps of: - Detect the cadence of the crank transmission (104) (21); - Detect the rear wheel speed of (22) rear wheel (110); - Determine the transmission ratio between the crank transmission (104) and the rear wheel (110) as described in (23); - Based on the cadence, rear wheel speed and transmission ratio, the engagement ratio (24) (31) is obtained. - Based on the determined intervention ratio (31), the motor torque (25) is generated.

2. The method according to claim 1, further comprising the following steps: - When the obtained intervention ratio (31) corresponds to at least one predetermined intervention threshold (34), identify (26) active rider intervention; - Wherein, the generation of the motor torque (25) is achieved based on the intervention of the identified active rider.

3. The method according to any one of the preceding claims, - in, The following characteristic curve (33) is defined, which defines the target motor support (32) according to the intervention ratio (31); and - Wherein, the generation of the motor torque (25) is achieved based on the characteristic curve (33).

4. The method according to claim 3, - Wherein, the characteristic curve (33) defines the intervention region (33a) in which the intervention ratio (31) is 1; and - Wherein, the intervention area (33a) defines the predetermined intervention motor support (32a) as the target motor support (32).

5. The method according to claim 4, - Wherein, the characteristic curve (33) has an enhanced region (33b), and the intervention ratio (31) corresponding to the enhanced region is greater than 1, preferably greater than or equal to 1.05; and - in, The enhanced region (33b) defines the enhanced motor support (32b) as the target motor support (32), and the enhanced motor support is greater than the intervention motor support (32a).

6. The method according to claim 4 or 5, - Wherein, the characteristic curve (33) defines the following idle region (33c), the intervention ratio corresponding to the idle region being less than 0.8, preferably less than 0.5; and - in, The idling area (33c) limits the target motor support (32) to zero.

7. The method according to claim 6, - Wherein, the characteristic curve (33) defines the following slope region (33d), which lies between the idling region (33c) and the intervention region (33a); and - in, The slope region (33d) defines the continuous lifting of the target motor support (32) according to the determined intervention ratio (31).

8. The method according to claim 7, wherein, The slope region (33d) has at least two sub-regions (33e, 33f), which have different inclines for the continuous lifting of the target motor support (32).

9. The method according to any one of claims 3 to 8, further comprising the following step: - The feature curve (33) is scaled according to the different support modes of the electric bicycle (100), preferably the manually operable support mode.

10. The method according to any one of the preceding claims, - Wherein, the gear ratio (23) is obtained based on the signal from the shift system (106); and / or - in, The gear ratio (23) is determined based on the detected cadence of the crank transmission (104) and the detected rear wheel speed of the rear wheel (110), especially when active rider intervention is detected.

11. The method according to any one of the preceding claims, wherein, The detection (21) of the cadence of the crank drive (104) is performed by means of a higher time sampling rate than the detection (22) of the rear wheel speed of the rear wheel (110).

12. A drive assembly (10) for an electric bicycle (100) comprising a control unit (50) configured to perform the method (20) according to any one of the preceding claims.

13. An electric bicycle comprising the drive assembly (10) according to claim 12.

14. The electric bicycle according to claim 13, wherein, The electric bicycle (100) or the drive assembly (10) is constructed without a torque sensor and / or without a bearing force sensor.

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