Method for operating drive assembly of electric bicycle

Abstract

To provide an electric bicycle that can attain shift processing without a load.SOLUTION: The present invention relates to a method for operating a drive assembly 10 of an electric bicycle 100. The drive assembly 10 includes: a drive unit 1; and a gear shift mechanism 2 that can be controllably operated. The method for operating the drive assembly 10 of the electric bicycle 100 includes: obtaining a drive load of a drive unit 1 at present; controlling and increasing the rotation speed of a prime mover of the drive unit 1 to the engagement rotation speed at which an engagement load determined in advance by the drive load is attained; and controlling and shifting by the gear shift mechanism 2 during operation of the drive unit 1 at the maximum engagement rotation speed.SELECTED DRAWING: Figure 1

Description

Technical Field

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

Background Art

[0002] An electric bicycle having a drive assembly, the drive assembly having a drive unit that generates a driving moment that power-assistedly assists the pedaling force of a driver, and a gear shift mechanism having a plurality of different gear stages, is known. At that time, an automatic or semi-automatic gear shift mechanism capable of performing an automatic shift process is also known. At that time, for example, when it is a chain-type shift mechanism, it is also known to automatically operate the drive unit of the electric bicycle during the execution of the shift process so that a gear change can be performed even in a stopped state. This type of electric bicycle is shown in Patent Document 1.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

[0004] On the other hand, the method according to the present invention having the features of claim 1 is excellent in that an automatic shift process in an electric bicycle can be carried out particularly simply and efficiently. In particular, at that time, a particularly low-wear and rapid shift can be made possible by simple means. This is a method for operating a drive assembly of an electric bicycle according to the present invention, the drive assembly having a drive unit and a controllably operable gear shift mechanism, a step of obtaining a current driving load of the drive unit, a step of controlling and increasing the rotational speed of the prime mover of the drive unit to an engagement rotational speed at which the driving load reaches a predetermined engagement load, Controlling and shifting during operation of the drive unit at a maximum engagement rotational speed by means of a gearshift mechanism; is achieved by a method of operating a drive assembly of an electric bicycle including the same.

[0005] A drive load is determined, in particular torque and / or force.

[0006] Preferably, as the drive load, the prime mover load of the drive unit is determined, i.e., in particular, the currently occurring prime mover moment of the drive unit. The prime mover load can be calculated directly, for example by means of a sensor, or alternatively, from the current supplied to and flowing through the drive unit and known prime mover parameters. Alternatively or additionally, preferably, as the drive load, the load in a passive element, for example in a chainring, and / or in a transmission element, for example in a chain, may be determined. Further alternatively or additionally, preferably, as the drive load, the load at another point of the power train of the electric bicycle, for example in a sprocket set provided at a rear wheel hub, may be determined.

[0007] Preferably, the step of determining the current drive load, in particular the prime mover load directly occurring in the drive unit, is carried out by an estimation based on the operation of the drive unit. Preferably, the drive load can be estimated based on an operation signal and / or an operation current for operating the drive unit. Alternatively or additionally, preferably, the current drive load may be determined by a sensor, for example a torque sensor and / or a force sensor.

[0008] Preferably, the drive loads in different sections of the power train of the electric bicycle can be determined from sensor signals and preferably additionally from a mathematical model of the drive unit and the power train. In particular, as a sensor or detection method, direct detection of the prime mover moment, for example measurement by a torque sensor, and / or calculation of the prime mover moment based on current measurement together with known prime mover parameters, the detected rotor position signal of the drive unit can be used.

[0009] The load regarded as the engagement load is, in particular, this type of load characteristic of the minimum load that causes the engagement of the drive unit to propulsion via the power train of an electric bicycle. That is, at least at the engagement load, the operation of the drive unit at least partially causes the propulsion of the electric bicycle. In other words, by raising the prime mover rotational speed to the engagement rotational speed reaching the engagement load, the drive unit is rotated at a speed such that the mechanical engagement for transmitting torque of the drive unit to the power train becomes possible.

[0010] In other words, in this method, the prime mover rotational speed is preferably incrementally raised until the drive unit reaches a state of being engaged with the path through which torque is transmitted in the power train. In other words, the operation of the drive unit is carried out so as to be brought into the engaged state by controlling and raising the prime mover rotational speed. The shift process is then carried out by controlling and shifting at the engagement rotational speed at which this engaged state exists at maximum. That is, preferably, it is shifted when the rotational speed is at least slightly less than the engagement rotational speed.

[0011] This method thereby provides the advantage that an automatic shifting process can be carried out by particularly simple means, with only slight wear and in a short time. The current driving load is estimated, for example, based on software, and the prime mover speed is adjusted to the engaged state, such that the shifting process can be carried out at the highest possible prime mover speed while no significant engagement for torque transmission of the drive unit has yet occurred. Thereby, for example, a shifting process with as little load as possible can be achieved, so that the shifting process can be carried out particularly smoothly and with only slight wear. At this time, it is particularly advantageous that the automatic shifting process and the manual shifting process can be carried out without pedal operation by the driver of the electric bicycle. For example, when the electric bicycle is coasting, the shifting process can be carried out such that the drive unit is operated at a shifting speed that barely falls below the engagement speed, at which time the drive unit drives the chain drive of the electric bicycle and can thus provide an efficient, low-wear and as rapid as possible shifting process. In particular, when the driver starts pedaling again, the desired gear stage is already engaged without the need for further action by the driver.

[0012] The dependent claims show preferred developments of the invention.

[0013] Preferably, the method further includes a step of determining a shifting speed such that the shifting speed is smaller than the engagement speed by a predetermined shifting offset. At this time, the step of shifting by controlling with a gear shifting mechanism is carried out at the shifting speed. That is, when the method is implemented, a predetermined shifting speed at which the drive unit should rotate and the shifting is carried out is set. The shifting speed is, at this time, smaller than the engagement speed by the shifting offset. In particular, the shifting speed is always set such that, however, the shifting speed is always greater than 0 revolutions per minute. Thereby, it is ensured that the shifting is carried out simply and with high reliability without engagement of the drive unit to the power train.

[0014] Particularly preferably, the shift offset is at least 5% of the sought current engagement rotational speed. That is, the shift rotational speed is 5% less than the engagement rotational speed. Preferably, the shift offset is at least 10%, particularly at most 30%, of the engagement rotational speed. Alternatively, preferably, the shift offset is at least 5 revolutions per minute. That is, the shift offset may be defined as a predetermined number of rotations that reduces the engagement rotational speed to the shift rotational speed. Preferably, the shift offset is at least 10 revolutions per minute, particularly at most 30 revolutions per minute. By setting the shift offset as a predefined fixed percentage or an absolute ratio, a particularly simple and reliable reduction of the shift rotational speed can be achieved.

[0015] Preferably, the method further comprises the step of controlling and operating the drive unit at the shift rotational speed for at least one predefined time span and / or for at least one predefined number of rotations. In particular, the predefined number of rotations can be regarded as the rotation of the prime mover of the drive unit or, alternatively, preferably, as the number of rotations in a power train, for example a sprocket set. Preferably, the predefined time span can be at least 0.5 seconds, preferably at least 1 second, preferably at most 3 seconds. More preferably, the predefined number of rotations can be at least 1 rotation, preferably at least 2 rotations, particularly at most 4 rotations. Thereby, after determining the shift rotational speed, the drive unit can be rotated for a certain time and / or a certain distance, so that as a result, during this rotation, the shift process can be carried out and completed particularly simply and reliably. This ensures that a particularly reliable and low-wear shift can be provided without significant engagement of the drive unit with the power train.

[0016] Preferably, the engagement load is at most 15 Nm, preferably at most 5 Nm, particularly at least 3 Nm. Thereby, the engaged state can be recognized particularly easily on the basis of a fixedly defined value. For example, these values are based on the assumption that the corresponding torque is sufficiently small, so that, as a result, a significant torque transmission via a power train, which could cause, for example, the propulsion of an electric bicycle, is not carried out. In particular, an engagement load of this magnitude is insufficient to overcome the friction within the power train. At the same time, this value is defined high enough to be able to avoid, for example, a false recognition of the engaged state.

[0017] More preferably, the method further includes a step of determining a target rotational speed. The step of controlling and increasing the prime mover rotational speed is thereby carried out by a continuous increase in the target rotational speed. Considered as a continuous increase is, in particular, a temporally continuous incremental increase in the target rotational speed. That is, a target rotational speed to which the prime mover rotational speed is to be increased is set. For example, this increase in the prime mover rotational speed to the target rotational speed is carried out by a controller of the drive unit. The target rotational speed can thereby be increased, for example, continuously until the engagement rotational speed is reached. Thereby, a particularly simple and flexible implementation of the method by a control unit of the drive unit can be made possible.

[0018] Preferably, the method further includes a step of limiting the target rotational speed to a maximum target rotational speed. Preferably, the maximum target rotational speed is determined based on the determined rear wheel rotational speed of the electric bicycle at that time and, additionally, the determined current gear ratio. The rear wheel rotational speed can preferably be determined by a rotational speed sensor. The current gear ratio can be determined, for example, based on the rotational speeds of the power train and the rear wheel detected by a sensor and / or based on the tracking of the shifting process. Preferably, the maximum target rotational speed corresponds to the determined rear wheel rotational speed multiplied by the determined current gear ratio, preferably minus a predetermined rotational speed offset. The rotational speed offset can correspond to, for example, at least 5%, particularly at least 10%, preferably up to 30% of the determined maximum target rotational speed. Alternatively, preferably, the rotational speed offset can be a predetermined amount of rotational speed, for example, at least 10 revolutions per minute, particularly up to 30 revolutions per minute. Thereby, it can be provided to limit the increase in the prime mover rotational speed, which results in providing further measures that can simply and reliably prevent the power train from engaging and thus avoid the propulsion of the bicycle by controlling and operating the drive unit.

[0019] Preferably, initially, the determined current prime mover rotational speed is set as the target rotational speed. Alternatively, preferably, initially, the calculated rotational speed corresponding to subtracting a predetermined rotational speed offset from the determined current rotational speed is set as the target rotational speed. The rotational speed offset may be, for example, a percentage ratio, for example, at least 2%, particularly up to 10% at most, or alternatively, a predetermined absolute ratio, for example, at least 2 revolutions per minute, particularly up to 10 revolutions per minute at most. Further alternatively, preferably, initially, a predefined rotational speed, for example, at least 30 revolutions per minute, preferably at least 50 revolutions per minute, particularly up to 70 revolutions per minute at most, may be set as the target rotational speed. Further alternatively, preferably, initially, the determined current rear wheel rotational speed is multiplied by the determined current gear ratio, and preferably, a predetermined offset is subtracted and set as the target rotational speed. What is regarded as the initial setting is, in particular, that the target rotational speed is correspondingly set at the start of this method in this way, i.e., a certain specific starting point is defined. Thereby, this method can be implemented particularly simply and efficiently.

[0020] Preferably, the method further includes the step of increasing the target rotational speed in response to the elapse of a predetermined time span. That is, the step of increasing the target rotational speed can be triggered and implemented in terms of time. Alternatively or additionally, preferably, the step of increasing the target rotational speed is implemented in response to a predetermined sensor signal. The sensor signal can be, for example, a rotation signal of a rotational speed sensor, for example, at the rear wheel, or alternatively, in the drive unit, and / or a speed sensor. Thereby, a defined criterion for increasing the target rotational speed can be provided simply, and thereby, by simple means, it can be achieved to adjust to the engagement state of the drive unit.

[0021] Preferably, the step of increasing the target rotational speed is stopped when the driving load reaches or exceeds a predetermined load threshold. The load threshold is, for example, a predefined maximum load for the driving load. Thereby, shifting under high load and propulsion of the bicycle can be avoided particularly easily. Preferably, after reaching the predetermined load threshold, a new, initial setting of the target rotational speed is carried out particularly as described above. Preferably, the increase in the target rotational speed can alternatively or additionally also be carried out when a signal indicating that another carrier, for example the next gear stage has been reached during shifting, and / or when there is a gear change request, for example by an automatic shift mechanism or a manual operation.

[0022] Particularly preferably, when the detected current pedaling frequency is equal to or higher than the current engine speed, preferably, when the pedaling frequency is greater than the current engine speed by at least 5%, preferably at least 15%, particularly up to 30%, and / or when the pedaling frequency is greater than the current engine speed by at least 5 revolutions per minute, preferably at least 10 revolutions per minute, particularly up to 20 revolutions per minute, the target speed is reset, particularly by a step of newly determining the target speed for the first time, and the method further includes a step of resetting. Alternatively or additionally, preferably, the resetting of the target speed is carried out when the engine speed is equal to or lower than a predetermined threshold value for at least one predetermined time span and / or when the engine speed is equal to zero for at least one predetermined time span. Further alternatively or additionally, preferably, the resetting of the target speed is carried out when the engine speed remains at a value smaller than the target speed for at least one predetermined time span, preferably, this value is smaller than the target speed by at least 5%, preferably at least 15%, particularly up to 30%, and / or this value is smaller than the target speed by at least 5 revolutions per minute, preferably at least 10 revolutions per minute, particularly up to 20 revolutions per minute. Particularly, the target speed is not reset to a value smaller than zero at this time, however. Thereby, an optimal adaptation of the shift mechanism to the changing driving state can be made possible simply and with high reliability. In addition, a constantly suitable and highly reliable implementation of the method in all driving states can be ensured, for example, when the bicycle slows down and the rear wheel rotation speed decreases, without the power train remaining engaged for a long time during the method.

[0023] More preferably, the step of determining the current driving load is performed based on an operation signal and / or an operation current for performing the operation of the drive unit. For example, what can be regarded as an operation signal is a signal of a control unit configured to control and operate the drive unit. Preferably, what can be regarded as an operation current is a current for operating the drive unit. Further alternatively or additionally, preferably, the step of determining the current driving load may be performed based on a rotor position signal of a rotor position sensor of the drive unit. That is, in this case, for example, the movement of the rotor of the drive unit may be obtained or tracked by the rotor position sensor, and based on this, the driving load can be estimated. Thereby, the driving load can be estimated with high reliability by a simple means.

[0024] Particularly preferably, the method is carried out, in particular exclusively, during the driving operation of the electric bicycle, in particular during forward movement. Alternatively or additionally, preferably, the method may be carried out with the electric bicycle in a stationary state.

[0025] Furthermore, the present invention leads to a drive assembly for an electric bicycle, comprising a drive unit, a shift system, and a control unit. Preferably, an operating device may additionally be provided, by means of which the operator of the electric bicycle can perform a manual operation to initiate a shifting process, for example mechanically or electrically. The shift system preferably has a gearshift mechanism having a plurality of different gear stages. For example, the gearshift mechanism may be formed as a chain-type shift mechanism having a plurality of sprockets. The control unit is configured to control and operate the drive unit and to control and operate the shift system in that case. In addition, the control unit is configured to carry out the method described.

[0026] Furthermore, the present invention relates to an electric bicycle comprising the drive assembly described.

[0027] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Brief Description of the Drawings

[0028]

Figure 1

Figure 2

Modes for Carrying Out the Invention

[0029] Preferably, in all the figures, the same reference numerals are assigned to all the same components, elements and / or units.

[0030] FIG. 1 shows a simplified schematic diagram of an electric bicycle 100 in which a method of operating a drive assembly 10 of the electric bicycle 100 according to a preferred embodiment of the present invention is implemented.

[0031] The drive assembly 10 includes a drive unit 1, and the drive unit 1 has a prime mover which is particularly an electric motor. Electrical energy can be supplied to the prime mover by an electrical energy accumulator 109 of the electric bicycle 100.

[0032] The drive unit 1 is arranged within the area of the bottom bracket of the electric bicycle 100. The driving force generated by the driver of the electric bicycle 100 by muscle power can be assisted in a power-assisted manner by the prime mover moment generated by the prime mover. The muscle power of the driver can be applied via the crank mechanism at that time.

[0033] The drive assembly 10 further includes a control unit 5, and the control unit 5 is configured to control and operate the drive unit 1. For example, the control unit 5 can control the operating current for operating the prime mover of the drive unit 1.

[0034] In addition, the drive assembly 10 comprises a gearshift mechanism 2, which can likewise be controllably operated by the control unit 5. Alternatively or additionally, preferably, the gearshift mechanism 2 can be manually operated by the driver of the electric bicycle 100 using an operating device 115 which can, for example, have a shift lever.

[0035] The gearshift mechanism 2 is arranged, for example, at least on the rear wheel hub of the electric bicycle 100 and has a plurality of shiftable gear stages. In particular, the gearshift mechanism is a chain-type shift mechanism having a plurality of sprockets.

[0036] The drive unit 1 further has a sensor unit 6 having a rotor position sensor, by means of which the rotor position of the rotor of the prime mover can be detected. Additionally, the sensor unit 6 may have a current sensor for detecting the operating current for operating the prime mover of the drive unit 1. Based on the sensor signals of the rotor position sensor and / or the current sensor and preferably, additionally, from the pre-known characteristics of the prime mover, the prime mover torque generated by the drive unit 1 can then be determined.

[0037] FIG. 2 shows a highly simplified schematic view of the steps of a method 20 for operating the drive assembly 10 of the electric bicycle 100.

[0038] In this method 20, first, a step 25 of determining a target rotational speed for the drive unit 1 is carried out. At the first execution of the method 20 or after a step 27 of resetting the target rotational speed (as will be explained further below), initially, a pre-specified rotational speed of, for example, 30 revolutions per minute can be set as the target rotational speed. Alternatively, preferably, the target rotational speed can be set by multiplying the detected rear wheel rotational speed by the current gear ratio and subtracting a pre-determined offset, or by subtracting a pre-determined rotational speed offset based on the detected current prime mover rotational speed.

[0039] The step 27 of resetting the target rotational speed can be implemented when one or more states of the drive assembly 10 occur at that time. Specifically, the step 27 of resetting is implemented to the initially determined target rotational speed or, for example, to a pre-specified and set rotational speed at that time.

[0040] The step 27 of resetting can be implemented when it is recognized, based on the step 28 of detecting based on a sensor, that the current target rotational speed no longer matches the current state or operation mode at that time. This particularly applies when the detected current pedaling frequency of the driver of the electric bicycle 100 is equal to or higher than the current rotational speed of the prime mover of the drive unit 2. Further, as a criterion for the step 27 of resetting, it can be used that the rotational speed of the prime mover remains below a pre-determined threshold value, and / or equal to zero, and / or a value smaller than the target rotational speed for at least one pre-determined time span.

[0041] The initially determined target rotational speed can be incrementally increased at a pre-determined time point, that is, after the elapse of a pre-determined time span, each time in step 26. Alternatively or additionally, this increase may be implemented in response to the detection of a pre-determined sensor signal, for example, a pulse of the rotational signal of a rotational speed sensor and / or a speed sensor. Alternatively or additionally, preferably, this increase may be implemented in response to another signal, for example, a gear stage signal indicating the arrival at the next gear stage, or a gear change signal requesting a new gear change, or the like.

[0042] At this time, the step 26 of increasing the target rotational speed can be stopped when the drive load determined as described below of the drive unit 1 reaches or exceeds a pre-determined load threshold value, for example, the specified maximum torque.

[0043] In this method 20, subsequently, step 21 of determining the current driving load of the drive unit 1 is performed. As the driving load, preferably, the current prime mover load is determined, that is, in particular, the current prime mover torque of the prime mover of the drive unit 1 is determined. This prime mover torque is estimated in particular by an estimation based on the operating current for operating the drive unit 1. This may be performed, for example, by direct detection using a torque sensor. Alternatively or additionally, the driving load may be calculated based on the measurement of the operating current of the prime mover and known prime mover parameters. Additionally, the rotor position signal of the rotor position sensor of the sensor unit 6 may be used to estimate the current driving load. Alternatively, preferably, a force measurement or a moment measurement may be performed at any location within the power train, for example, at a chain ring or a sprocket set, to determine the driving load.

[0044] By controlling and operating the drive unit 1, subsequently, step 22 of controlling and increasing the prime mover speed of the drive unit 1 to the engagement speed is performed. The engagement speed is defined to form the lowest speed at which a mechanical engagement of the drive unit 1 to the power train of the electric bicycle 100 is caused. This corresponds in particular when a predetermined engagement load of up to 10 Nm is reached.

[0045] In response to reaching the engagement load, step 24 of determining the shift speed is performed.

[0046] Step 24 of determining the shift speed is performed such that the shift speed is lower than the engagement speed at which the engagement load is reached by a predetermined shift offset. The shift offset is then at least 10%, preferably 15% of the engagement speed. Alternatively, preferably, a predetermined value, for example, at least 10 revolutions per minute, preferably 15 revolutions per minute, may be used as the shift offset. That is, after the prime mover speed of the drive unit 1 reaches the engagement speed, it is decreased to a lower shift speed.

[0047] After step 24 of determining the shift rotation speed, in step 23, the drive unit 1 is controlled and operated to rotate at this shift rotation speed for at least one predetermined number of rotations. Preferably, this step 23 of operating the drive unit 1 is carried out such that the prime mover is rotated for exactly two complete rotations. Thereby, during this operation 23, it can be ensured that at some point during the shift process, the shift process is carried out by the chain jumping to the corresponding sprocket of the target gear stage. Preferably, this can be preferably initiated by the corresponding operation of the shift process by the control unit 5 when the shift process is carried out automatically.

[0048] At this time, the method 20 can provide automatic shifting of the shift system 2 particularly simply and by simple and low-cost means, and particularly provides the advantages that only slight wear is possible and the implementation can be as rapid as possible. In particular, at this time, by the suitable operation of the drive unit 1 in the engaged state, shifting can always be possible, for example, even when the driver is not pedaling, and particularly when the driver-free wheel state exists, for example, in the chain ring.

Explanation of reference numerals

[0049] 1 Drive unit 2 Gear shift mechanism 5 Control unit 6 Sensor unit 10 Drive assembly 20 Method for operating the drive assembly of an electric bicycle 21 Step of determining the current drive load of the drive unit 22 Step of increasing the rotational speed of the prime mover of the drive unit to the engagement rotational speed 23 Step of operating the drive unit at the shift rotational speed 24 Step of determining the shift rotational speed 25 Step of determining the target rotational speed for the drive unit 26 Step of increasing the target rotational speed Step of resetting the target rotation speed Step of detecting based on a sensor 100 Electric bicycle 109 Electrical energy accumulator 115 Operating device

Claims

1. A method for operating a drive assembly (10) of an electric bicycle (100), wherein the drive assembly (10) has a drive unit (1) and a controllably operable gear shifting mechanism (2), and the following steps, namely, a step (21) of determining a current drive load of the drive unit (1); a step (22) of controlling and increasing the prime mover rotational speed of the drive unit (1) to an engagement rotational speed at which the drive load reaches a predetermined engagement load; a step of controlling and shifting by the gear shifting mechanism (2) during operation of the drive unit (1) at the engagement rotational speed at most; are included, A method for operating a drive assembly of an electric bicycle.

2. A method further includes a step (24) of determining a shift rotational speed such that the shift rotational speed is smaller than the engagement rotational speed by a predetermined shift offset, and at this time, the step of controlling and shifting is performed at the shift rotational speed, and in particular, the shift rotational speed is always greater than 0 revolutions per minute, The method according to claim 1.

3. The shift offset is at least 5% of the engagement rotational speed, preferably at least 10%, particularly at most 30%, or The shift offset is at least 5 revolutions per minute, preferably at least 10 revolutions per minute, particularly at most 30 revolutions per minute, The method according to claim 2.

4. The method further includes a step (23) of controlling and operating the drive unit (1) at the shift rotational speed for at least one predetermined time span and / or for at least one predetermined number of rotations, The method according to any one of claims 2 or 3.

5. The engagement load is at most 15 Nm, preferably at most 10 Nm, particularly at most 5 Nm, preferably at least 3 Nm, The method according to any one of claims 1 to 4.

6. The method further includes a step (25) of determining a target rotational speed, and at this time, the step (22) of controlling and increasing the prime mover rotational speed is performed by a continuous increase in the target rotational speed, The method according to any one of claims 1 to 5.

7. A step of limiting the target rotational speed to a maximum target rotational speed, and in particular, the step further includes determining the maximum target rotational speed based on the determined rear wheel rotational speed and the determined current gear ratio, The method according to claim 6.

8. First, as the target rotational speed, determine the current prime mover rotational speed obtained, or subtract a predetermined rotational speed offset from the obtained current prime mover rotational speed, or multiply the obtained current rear wheel rotational speed by the obtained current gear ratio, and in particular subtract the offset, and set it. The method according to claim 6 or 7.

9. Further including step (26) of increasing the target rotational speed in response to the elapse of a predetermined time span and / or in response to a predetermined sensor signal, in particular a rotational signal of a rotational speed sensor and / or a speed sensor. The method according to any one of claims 6 to 8.

10. Stop step (26) of increasing the target rotational speed when the driving load reaches or exceeds a predetermined load threshold. The method according to claim 9.

11. When the detected pedaling frequency is equal to or higher than the current prime mover rotational speed and / or When the prime mover rotational speed is equal to or lower than a predetermined threshold for at least one predetermined time span and / or When the prime mover rotational speed is equal to zero for at least one predetermined time span and / or When the prime mover rotational speed remains at a value smaller than the target rotational speed for at least one predetermined time span, Further including step (27) of resetting the target rotational speed. The method according to any one of claims 6 to 10.

12. Implement step (21) of determining the current driving load based on an operation signal and / or an operation current for operating the drive unit (1) and / or based on a rotor position signal of a rotor position sensor of the sensor unit (6) of the drive unit (1). The method according to any one of claims 1 to 11.

13. Implement the method according to any one of claims 1 to 12 during the running operation of the electric bicycle (100), in particular during forward movement.

14. A drive assembly of an electric bicycle (100), comprising A drive unit (1), A shift system (2), A control unit (5) configured to operate the drive unit (1) and the shift system (2), Comprising, The control unit (5) is further configured to implement the method according to any one of claims 1 to 13. A drive assembly of an electric bicycle (100).

15. An electric bicycle comprising the drive assembly (10) according to claim 14.

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