Electric bicycle with emergency running strategy

Abstract

The invention discloses a method for controlling an electric bicycle and an associated bicycle. The electric bicycle (301) comprises a battery (304), a drive motor (303) and an electrical circuit (305), wherein the battery (304) is designed to supply power both to the drive motor (303) and to the electrical circuit (305). The method here comprises the steps of determining (S1) a state of charge of the battery and changing (S2) an operating state from a first operating state to a second operating state when the state of charge falls below a first threshold value, wherein the drive motor (303) and the electrical circuit (305) are operated in a normal state in the first operating state; and the power consumption by the drive motor (303) is limited or the electrical circuit (305) is moved to a restricted operating mode in the second operating state.

Description

[0001] Electric bicycle with emergency gear strategy

[0002] Technical area

[0003] The present invention relates to a method for controlling an electric bicycle in which a drive motor and an electrical circuit are powered by a common energy source. In particular, the present invention relates to an emergency gear strategy for such an electric bicycle.

[0004] State of the art

[0005] State-of-the-art gear systems, such as derailleur gears, are known, which can be actuated both mechanically and electrically. Furthermore, bicycles with electric motor assistance, also referred to as electric bicycles, such as pedelecs or e-bikes, are known with various types of gear systems.

[0006] Problems can arise with such electric bicycles if both the electric drivetrain and the electric motor for propulsion support are powered by the same energy storage device or battery. In such a situation, limitations of the electric drivetrain and also the motor support can be expected if the battery charge level differs by a certain amount.

[0007] Description of the invention

[0008] It is therefore an object of the present invention to provide an electric bicycle and a control method for the same, which has improved behavior when the battery is at a low state of charge.

[0009] A method according to one embodiment of the present invention relates to a method for controlling an electric bicycle, wherein the electric bicycle has a battery and an electrical circuit, and wherein the battery is configured to supply both the drive motor and the electrical circuit with energy. An electric bicycle is understood here to be a bicycle with a pedal device which is operated at least temporarily using muscle power, but also has a drive motor. The drive motor is designed to assist the propulsion of the electric bicycle and can also be referred to as a drive device or electrical machine. This electrical machine serves to assist the operation of the pedal device operated by muscle power.A battery is an energy storage device that can store electrical charge and is preferably rechargeable via an external power source. The term battery also includes accumulators.

[0010] An electrical shifting system is one in which the shifting is activated by electrical impulses, for example, a rear derailleur or front derailleur being operated by these electrical impulses. The actuation can be automatic, i.e., based on an automatic gearshift, or based on a user request.

[0011] The first step in the process is to determine the battery's state of charge. This state of charge indicates the battery's remaining capacity relative to its nominal value. Those skilled in the art are familiar with various methods for determining the state of charge of a battery or energy storage device. Determining a state of charge here also includes determining a state of discharge.

[0012] In the next step, an operating state is to be changed from a first operating state to a second operating state when the charge level falls below a first threshold. Such an operating state can, for example, be an operating state of the electric bicycle's control system, i.e., an internal operating state of the electric bicycle's control device. Any value between a full charge and a full discharge of the battery can be defined as the threshold.

[0013] In the first operating state, the drive motor and the electrical circuit should operate in a normal state. A normal state can be understood, for example, as operation without any restriction of the respective performance or functionality. A predefined behavior of the components can also be provided as a normal state.

[0014] In the second operating state, either the power consumption of the drive motor should be limited or the electrical circuit should be put into a restricted operating mode.

[0015] To reduce power consumption, the maximum power consumption of the drive motor can be limited to a predefined value. This means that the assistance and thus, for example, the torque of the electric motor applied to the pedal unit or a wheel of the bicycle is limited. The output torque of the drive motor can also be limited, since the power consumption is related to the drive torque. Furthermore, a limit to zero can be set in such a way that the electric motor is switched off.

[0016] When operating an electrical circuit in a restricted operating mode, the functionalities and properties of the electrical circuit can be limited in such a way that an actuation occurs differently than in the normal state. Examples include changing the switching behavior, suppressing the actuation, switching to a predetermined emergency gear, or similar.

[0017] Accordingly, switching to the second operating state can ensure that the effects of a lower battery charge level on the functionality of the electrical circuit in particular are reduced, since, on the one hand, the functionality of the electrical circuit is ensured by reducing the power consumption of the drive motor or reducing it to zero. On the other hand, the functionality of the electrical circuit can be ensured by changing the switching behavior of the circuit.

[0018] In one embodiment, the power consumption can be limited in the second operating state by derating the drive motor. Accordingly, the motor power is reduced, which in turn reduces the motor's power consumption. This ensures longer functionality, especially of the electrical circuit.

[0019] In a further embodiment, the power consumption can be limited in the second operating state by shutting down the drive motor. Since the motor's power consumption is thus reduced to zero, it is ensured that the electrical circuit remains operational for a significantly longer period of time.

[0020] In a further embodiment, in the second operating state, the electrical circuit can be put into a restricted operating mode such that the circuit is switched into a predefined emergency gear and further switching operations are preferably suppressed. A predefined emergency gear can be predefined, for example, by a user using an application. If the threshold value is reached, the circuit switches into this predefined emergency gear. This allows the circuit to be switched into a gear in which progress using muscle power alone is possible even if the electrical assistance from the drive motor has failed. If further switching operations are then suppressed, the user can no longer switch out of this emergency gear and progress in the emergency gear is thus ensured.

[0021] In a further embodiment, in the second operating state, the electrical circuit can be placed in a restricted operating mode such that manual gear changes by the user are prevented and gear shifts are controlled by an automatic gearshift. Accordingly, gear shift requests received from the user, for example, via an input device, can be suppressed. By selecting the gears using an automatic gearshift, a control behavior suitable for the still possible level of assistance and the still possible number of gear shifts can then be developed. For example, a gear shift can occur significantly less frequently than in a conventional automatic mode in order to reduce the power consumption of the electrical circuit.Furthermore, for example, a gear selection can only be made in such a way that even if the battery charge level required for a gear change is not reached, progress in the currently selected gear is only possible using muscle power.

[0022] In a further embodiment, a third operating state is also formed, which is switched to when the state of charge falls below a second threshold. This second threshold can, for example, be lower than the first threshold.

[0023] The aforementioned possible controls for the electrical circuit or the power consumption of the drive motor can also be implemented in the third operating mode. Accordingly, it is also possible to take appropriate measures in multiple stages if certain charge levels are successively exceeded.

[0024] For example, in a first stage, and thus in the second operating mode, the power consumption of the electric motor can be reduced by means of derating. In a further stage, and thus in the third operating mode, a predefined emergency gear could then be engaged to ensure progress.

[0025] Consequently, the addition of a further operating state with a further threshold allows an appropriate sequence of measures to be taken to ensure the functionality of the electric motor and / or the electrical circuit in an appropriate manner for as long as possible, even if the battery charge level decreases.

[0026] Accordingly, a further embodiment provides for a further fourth operating state with a third threshold. This can also be configured according to the above explanations.

[0027] The addition of a fourth operating state allows the control to be even more precise depending on the charge level.

[0028] For example, the electric motor can first be derated in the second operating state, then only automatic shifting can be permitted in a third operating state, as described above, and then an emergency gear can be engaged in the fourth operating state, as already described above. This allows for further improved adaptation of the power of the electric motor and the electrical circuit depending on the charge state.

[0029] The above-mentioned procedural steps are not limited to the sequence shown, but can also be carried out in a different order if technically possible.

[0030] Furthermore, the present invention relates to an electric bicycle having a battery, a drive motor and an electrical circuit, wherein the battery is configured to supply both the drive motor and the electrical circuit with energy, and wherein the electric bicycle further comprises a control device configured to carry out a method according to one of the above-mentioned embodiments.

[0031] For the definition of the terms, please refer to the above explanations.

[0032] A control device can, for example, be a microprocessor, either externally or in one of the other components listed here. The control device can also be implemented as a software component in existing software, which is executed on an existing microprocessor or computing unit. Distribution of the control device's functionalities across multiple microprocessors can also be provided.

[0033] Short description of the characters

[0034] Figure 1 shows a diagram illustrating the change of operating states according to one embodiment.

[0035] Figure 2 shows a sequence of the method according to one embodiment.

[0036] Figure 3 shows a schematic representation of the device according to one embodiment. Detailed description of the embodiments

[0037] Figure 1 shows the changes in operating states depending on the battery's state of charge. This will be described below with reference to the method shown in Figure 2 and the schematic representation of the device shown in Figure 3.

[0038] As can be seen, a possible course of a state of charge over time is plotted in Figure 1. First, the control device 302 of the bicycle 301 in Figure 3 determines the state of charge of the battery 304, step S1 in Figure 2. If it is determined that the state of charge of the battery falls below a first threshold value, as is the case at time P1 in Figure 1, a change is made from a first operating state to the second operating state, step S2 in Figure 2.

[0039] In the present example, the drive motor 303 in Figure 3 is first derated, i.e. the power consumption of the drive motor 303 is limited in order to maintain the functionality of the drive motor 303 and the electrical circuit 305 for as long as possible.

[0040] If it is subsequently determined at time P2 that the charge level of battery 304 falls below the second threshold, the system switches to the third operating state at time P2 in Figure 1, step S3 in Figure 2. In this third operating state, in the present example, the power consumption of drive motor 303 is reduced to zero by switching off drive motor 303. Thus, switching with electrical circuit 305 is possible for a significantly longer period, since no electrical power is consumed by drive motor 303.

[0041] If, however, it is determined at time P3 in Figure 1 that the third threshold is also undershot, the controller switches to operating state 4, step S4 in Figure 2. In this example, the electrical circuit 305 is activated to engage an emergency gear, which can be pre-determined by the user, for example, using an application. This emergency gear allows the rider to cover the remaining distance on their bicycle without changing gear.

[0042] P1 Time of change from operating state 1 to operating state 2

[0043] P2 Time of change from operating state 2 to operating state 3

[0044] P3 Time of change from operating state 3 to operating state 4

[0045] S1 Determining the state of charge

[0046] S2 Change to operating state 2

[0047] S3 Change to operating state 3

[0048] S4 Change to operating state 4

[0049] 301 Bicycle

[0050] 302 Control device

[0051] 303 drive motor

[0052] 304 Battery

[0053] 305 electrical circuit

Claims

Patent claims 1 . A method for controlling an electric bicycle (301), wherein the electric bicycle (301) has a battery (304), a drive motor (303) and an electrical circuit (305), and wherein the battery (304) is configured to supply both the drive motor (303) and the electrical circuit (305) with energy, the method comprising the steps of: - determining (S1) a state of charge of the battery; - changing (S2) an operating state from a first operating state to a second operating state when the state of charge falls below a first threshold value, wherein - in the first operating state, the drive motor (303) and the electrical circuit (305) are operated in a normal state; and - in the second operating state, the power consumption of the drive motor (303) is limited or the electrical circuit (305) is placed in a restricted operating mode.

2. Method according to claim 1, wherein in the second operating state a limitation of the power consumption is carried out by derating the drive motor (303).

3. Method according to one of the preceding claims, wherein in the second operating state, the power consumption is limited by switching off the drive motor (303).

4. Method according to one of the preceding claims, wherein in the second operating state the electrical circuit (305) is placed into a restricted operating mode such that the electrical circuit (305) is switched into a predefined emergency gear and preferably further switching operations are suppressed.

5. Method according to one of the preceding claims, wherein in the second operating state the electrical circuit (305) is placed in a restricted operating mode such that manual gear changes by the Users are prevented and gear changes are controlled depending on an automatic gearshift.

6. Method according to one of the preceding claims, further comprising the step: - Changing (S3) one operating state to a third operating state when the state of charge falls below a second threshold value, wherein - in the third operating state of a - a limitation of the power consumption of the drive motor (303); - placing the electrical circuit (305) into a restricted operating mode, wherein either the electrical circuit (305) is used to switch into a predefined emergency gear or manual gear changes by the user are prevented and switching operations are controlled as a function of an automatic gear system.

7. The method of claim 6, wherein the second threshold is lower than the first threshold.

8. Method according to one of the preceding claims, further comprising the step: - Changing (S4) one operating state to a fourth operating state when the state of charge falls below a third threshold, whereby - in the fourth operating state of one of - a limitation of the power consumption of the drive motor (303); - setting the electrical circuit (305) into a restricted operating mode, wherein either the electrical circuit (305) is used to switch into a predefined emergency gear or manual gear changes by the user are prevented and switching operations are controlled in dependence on an automatic gear system, wherein - the third threshold is lower than the second threshold.

9. Electric bicycle (301) comprising a battery (304), a drive motor (303) and an electrical circuit (305), wherein the battery (304) is arranged to supply both the drive motor (303) and the electrical circuit (305) with energy. supply, and wherein the electric bicycle (301) further comprises a control device (302) which is designed to carry out a method according to one of the preceding claims.

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