Method for operating a push-walk assistance of an electric bicycle

Abstract

The present invention relates to a method for operating a push-walk assistance of an electric bicycle, comprising the following steps: Operating a drive unit of the electric bicycle in a push-walk mode in order to move the electric bicycle at a target pushing speed, determining a drive torque of the drive unit, and, in a controlled manner, adjusting the target pushing speed according to the determined drive torque.

Description

[0001] Description

[0002] title

[0003] Method for operating a push assist of an electric bicycle

[0004] State of the art

[0005] The present invention relates to a method for operating a pushing aid of an electric bicycle, as well as to an electric bicycle.

[0006] Electric bicycles with a push-assist function are common. This function generates motor torque from the electric bicycle's drive unit, for example, in response to the electric bicycle rider pressing a button to assist the rider while pushing. Typically, such motor torque is generated to propel the electric bicycle at a predetermined target push speed. Particularly on steep inclines or uneven surfaces, the target push speed may be too high for the electric bicycle user to comfortably push the bicycle with the help of the push assist.

[0007] Disclosure of the invention

[0008] The method according to the invention with the features of claim 1 is characterized in that an optimized pushing aid for an electric bicycle can be provided, which can automatically provide a particularly high level of user comfort for a rider of the electric bicycle in a variety of possible pushing situations. In particular, optimal pushing support can be enabled in a particularly simple and convenient manner. This is achieved according to the invention by a method for operating a pushing aid for an electric bicycle, which comprises the steps of: - operating a drive unit of the electric bicycle in a pushing aid mode in order to move the electric bicycle at a desired pushing speed,

[0009] - Determining a drive torque of the drive unit, and

[0010] - controlled adjustment of the target pushing speed depending on the determined drive torque.

[0011] In particular, the drive unit is configured to generate a motor torque that can provide motor support for the pedaling torque generated by the rider's muscle power when the electric bicycle is in walking mode. In the push-assist mode, the drive unit can generate the motor torque, in particular, without additional pedaling by the rider.

[0012] For example, the walking assistance mode can be designed to be executable in response to a predetermined operation, for example by the user of the electric bicycle.

[0013] The drive torque is considered to be, in particular, the motor load of the drive unit required to achieve the current target pushing speed. For example, the drive torque can be detected using a torque sensor. Alternatively, the drive torque can preferably be estimated, for example, based on a control of the drive unit, such as, in particular, based on motor currents and preferably on rotor inertia, rotor speed, and / or rotor acceleration. In other words, the currently required drive power of the drive unit is determined.

[0014] Preferably, an instantaneous drive torque is determined as the drive torque, i.e., a drive load present at the exact instant in time. Alternatively or additionally, a specific time period around the instant in time can be considered. For example, an average value and / or a maximum value within this time period can be determined as the drive torque.

[0015] Preferably, a motor torque directly at the drive unit is determined as the drive torque, i.e., preferably an output torque of the drive unit. Alternatively or additionally, a torque at another point in the drive train of the electric bicycle can be determined as the drive torque. Advantageously, a rear wheel torque at a rear wheel of the electric bicycle can be determined as the drive torque, wherein the rear wheel torque can be calculated, for example, based on a known or determinable gear ratio of the drive train.

[0016] In other words, the method determines the drive unit's (preferably instantaneous) drive torque required to propel the electric bicycle at the target push speed during push-assist mode. Depending on the determined required drive torque, the target push speed is adjusted in a controlled manner, i.e., increased or decreased.

[0017] The method offers the advantage that the current drive load of the drive unit is taken into account when operating the electric bicycle's push assist, and the target push speed, at which the electric bicycle is to be moved by the motor drive via the drive unit, is specifically adjusted depending on the current drive load. This automatically adjusts the target push speed to the current pushing situation, so that the electric bicycle user can comfortably push the electric bicycle at any time with the assistance of the push assist. This automatically controls the electric bicycle user to provide a particularly high level of comfort when pushing the electric bicycle.

[0018] The subclaims show preferred developments of the invention.

[0019] Preferably, the controlled adjustment of the target pushing speed comprises reducing the target pushing speed as the drive torque of the drive unit increases. This means that the higher the determined drive torque of the drive unit, the more the target pushing speed is reduced. For example, the reduction of the target pushing speed can only occur when the determined drive torque exceeds a predetermined threshold. Preferably, the reduction of the target pushing speed occurs to at least a predefined minimum pushing speed. Thus, when high drive loads are required to move the electric bicycle in push-assist mode, which indicates in particular a demanding pushing situation, the target pushing speed can be automatically reduced to simplify pushing. This can provide a particularly high level of user comfort for the user of the electric bicycle.

[0020] Particularly preferably, the target pushing speed is equal to a predefined maximum pushing speed. This means that a maximum value is defined, which is set particularly at low drive loads. For example, the maximum pushing speed can be 4 km / h. This limits the maximum speed that can be provided in push assistance mode.

[0021] Preferably, the controlled adjustment of the target pushing speed is carried out by multiplying the maximum pushing speed by a pushing factor. The pushing factor is set to a value of a maximum of 1 and greater than 0 depending on the determined drive torque. Particularly preferably, a value of at least 0.5 is set for the pushing factor. Preferably, the pushing factor can be variably adjusted during the implementation of the pushing assistance mode. This means that the target pushing speed is reduced by multiplying the predefined maximum pushing speed by a value between 1 and 0, preferably at least 0.5. This allows the method to be carried out in a particularly simple and efficient manner.

[0022] The shift factor is preferably determined based on a predetermined characteristic map. The characteristic map can preferably be a multidimensional characteristic map. Alternatively, the characteristic map can preferably be designed as a one-dimensional characteristic curve, which in particular defines a precise relationship between the shift factor and the drive torque. This enables a particularly precise adaptation of the desired shift speed to different shifting situations with a view to optimal user comfort.

[0023] Further preferably, the controlled adjustment of the target pushing speed includes filtering the pushing factor. Preferably, the filtering can be performed using a low-pass filter and / or a rate limiter. This can, for example, prevent significant fluctuations in the target pushing speed, thereby making pushing the electric bicycle easier and more comfortable for the user.

[0024] Preferably, the target pushing speed is set equal to the maximum pushing speed each time the push assistance mode is started. This means that the maximum pushing speed is initially used as the starting value when the push assistance mode is started. Based on this, the controlled reduction can then take place depending on the drive torque. This allows the process to be implemented particularly simply and efficiently, with maximum assistance being available when pushing as often as possible.

[0025] Particularly preferably, determining the drive torque comprises determining a maximum drive torque within a predetermined first time period. This means that the maximum drive torque present within the first time period is determined. The target pushing speed is adjusted based on this determined maximum drive torque. This makes it possible, for example, to reliably achieve a sufficient reduction in the target pushing speed for a comfortable pushing process.

[0026] Preferably, determining the drive torque comprises determining an average drive torque within a predetermined second time period. For example, the first time period and the second time period can be identical, or alternatively, preferably different. This means that the average drive torque is determined for the predetermined second time period. This allows, in particular, fluctuations in the drive torque to be filtered out, thereby also avoiding significant fluctuations in the target pushing speed. This enables particularly consistent propulsion in push-assist mode.

[0027] Preferably, the controlled adjustment of the target speed additionally takes place as a function of a vehicle mass, in particular at least of the electric bicycle. In particular, the pushing factor, particularly preferably the characteristic map, is adjusted as a function of the vehicle mass. The vehicle mass can in particular be regarded as the vehicle mass excluding the electric bicycle. Alternatively, the vehicle mass can preferably be regarded as an entire system mass, which, for example, includes the mass of the electric bicycle and additional load or the like. The vehicle mass can, for example, be stored in a control unit of the electric bicycle and / or can be entered by the user of the electric bicycle. Preferably, a software-based estimation of the vehicle mass can also be carried out. Preferably, with a lower vehicle mass, a greater reduction in the target pushing speed occurs with increasing

[0028] Drive torque. This ensures sufficient assistance when pushing heavy electric bicycles, and a reliable reduction of the target pushing speed in difficult pushing situations for lighter bicycles.

[0029] Furthermore, the invention leads to an electric bicycle comprising a drive unit and a control unit. The control unit is configured to operate the drive unit in a controlled manner. Furthermore, the control unit is configured to carry out the described method for operating the push assist of the electric bicycle.

[0030] Short description of the drawings

[0031] An embodiment of the invention will be described in detail below with reference to the accompanying drawings. In the drawing:

[0032] Figure 1 is a simplified schematic view of an electric bicycle in which a method according to a preferred embodiment of the invention is carried out,

[0033] Figure 2 is a simplified schematic of a process of

[0034] Carrying out the method according to the preferred embodiment, and

[0035] Figure 3 is a simplified schematic view of a characteristic map used in the method according to the preferred embodiment.

[0036] Embodiments of the invention Preferably, all identical components, elements and / or units in all figures are provided with the same reference numerals.

[0037] Figure 1 shows a simplified schematic view of an electric bicycle 100 having a drive unit 1. The drive unit 1 is arranged in the region of a bottom bracket of the electric bicycle 100 and comprises a motor, which is in particular an electric motor. The motor can be supplied with electrical energy by means of an electrical energy storage device 109 of the electric bicycle 100.

[0038] By means of a drive torque generated by the drive unit 1, a pedal force generated by muscle power of a rider of the electric bicycle 100 can be motor-assisted.

[0039] The electric bicycle 100 also includes a control unit 50 configured to operate the drive unit 1. Preferably, the control unit 50 can be integrated into the drive unit 1, as shown schematically in Figure 1. The control unit 50 is also configured to implement a method for operating a pushing aid of the electric bicycle 100 according to a preferred embodiment of the invention.

[0040] The method is described in detail below, with reference to Figures 2 and 3. Figure 2 shows a simplified schematic view of signal flows during the implementation of the method.

[0041] In the method, in a push-assist mode, the drive unit 1 is actuated by the control unit 50 such that the drive unit 1 generates a drive torque. A rear wheel of the electric bicycle 100 is thereby driven via the drive train of the electric bicycle 100, causing the electric bicycle 100 to propel in the direction of travel A. The drive torque of the drive unit 1 can thus be used to assist the rider when pushing the electric bicycle 100.

[0042] The operation of the drive unit 1 in the push-assist mode is carried out in such a way, preferably controlled by the control unit 50, that the electric bicycle 100 is moved at a target push speed. This means that the drive torque is provided, in particular controlled, by the drive unit 1 in such a way that the electric bicycle 100 moves at the target push speed.

[0043] In the method, in the push assistance mode, a targeted adjustment of the target push speed takes place depending on the current engine load of the drive unit 1. In detail, the current drive torque of the drive unit 1 is determined. Based on this, the target push speed is reduced if a high drive torque is present, as described in detail below.

[0044] Figure 2 shows a highly simplified schematic view of a process sequence 10 of the method. The inputs are the determined drive torque 6 and the current target sliding speed 5.

[0045] Each time the push assistance mode is started, a predefined maximum push speed is initially used as the current target push speed to be achieved.

[0046] The drive torque 6 can be determined by sensor-based detection and / or by software-based estimation.

[0047] Based on the determined instantaneous drive torque 6, a maximum drive torque 61 is determined within a predetermined first time period, as well as an average drive torque 62 within a predetermined second time period. The two time periods can be identical or, alternatively, different for particularly flexible and precise detection.

[0048] Subsequently, a shift factor 51 is determined using a characteristic map 7, by which the current target shift speed 5 is multiplied. The determined shift factor 51 is then filtered using a filter 8, for example, low-pass filtered and / or limited using a rate limiter. The shift factor 51 thus determined and filtered is then multiplied by the current target shift speed 5 in multiplication step 9 to obtain the adjusted target shift speed 5'. The control unit 50 then controls the drive unit 1 in such a way as to move the electric bicycle 100 at the adjusted target shift speed 5'.

[0049] Figure 3 shows a simplified schematic view of the characteristic map 7, which is used to determine the shift factor 51. The characteristic map 7 defines a relationship between the shift factor 51 and the determined drive torque 6. At the origin 65 of the characteristic map 7 in Figure 3, the value 0 is defined for both axes.

[0050] In the characteristic map 7, two characteristic curves 71, 72 are shown as examples, each of which defines a relationship between the shift factor 51 and the drive torque 6.

[0051] Preferably, exactly one of the two characteristic curves 71, 72 is used for a specific electric bicycle 100. For example, these characteristic curves 71, 72 can be used for different types of electric bicycles 100, in particular with different vehicle masses. The first characteristic curve 71 can be used for an electric bicycle 100 with a high vehicle mass, such as a cargo bike. The first characteristic curve 71 defines higher push factors 51 at higher drive torques 6 in order to always ensure sufficient support in push-assist mode.

[0052] With the second characteristic curve 72, for example, a lighter electric bicycle 100 can be moved particularly precisely and comfortably when using the push assistance mode when higher drive torques 6 occur.

[0053] The two characteristic curves 71, 72 are defined such that, at a drive torque 6 of zero, a maximum push factor 56 with the value 1 is set as the push factor 51. This means that, in this case, the predefined maximum push speed is set as the adjusted target push speed 5'. Furthermore, the two characteristic curves 71, 72 are defined such that they define at least a minimum push factor 57 with the value 0.6 as the push factor 51. This always provides sufficient minimum support in push assistance mode.

[0054] The method therefore offers the advantage that, at high drive loads, a targeted reduction in the target pushing speed 5, at which the electric bicycle 100 is to be moved by motor assistance, is achieved. This allows for reliable pushing even in difficult pushing situations, such as steep inclines and / or uneven road surfaces.

[0055] Support can be provided to the user when pushing the electric bicycle 100 without the electric bicycle 100 being moved too quickly by the drive unit 1.

Claims

Claims 1 . A method for operating a push assist of an electric bicycle (100), comprising the steps: Operating a drive unit (1) of the electric bicycle (100) in a push-assist mode to move the electric bicycle (100) at a desired push speed (5), Determining a drive torque (6) of the drive unit (1), and controlled adjustment of the target pushing speed (5) depending on the determined drive torque (6).

2. The method according to claim 1, wherein the controlled adjustment of the target sliding speed (5) comprises: reducing the target sliding speed (5) with increasing drive torque (6).

3. Method according to one of the preceding claims, wherein the desired sliding speed (5) is at most equal to a predefined maximum sliding speed.

4. The method according to claim 3, wherein the controlled adjustment of the target sliding speed (5) is carried out by multiplying the maximum sliding speed by a sliding factor (51), and wherein the sliding factor (51) is set to a value of at most 1 and greater than 0, in particular at least 0.5, as a function of the determined drive torque (6).

5. The method according to claim 4, wherein the shift factor (51) is determined based on a predetermined characteristic map (7).

6. The method according to claim 4 or 5, wherein the controlled adjustment of the target sliding speed (5) comprises: filtering the sliding factor (51).

7. Method according to one of claims 3 to 6, wherein each time the pushing assistance mode is started, the target pushing speed (5) is set equal to the maximum pushing speed.

8. The method according to any one of the preceding claims, wherein determining the drive torque (6) comprises: determining a maximum drive torque (61) within a predetermined first time period.

9. The method according to any one of the preceding claims, wherein determining the drive torque (6) comprises: determining an average drive torque (62) within a predetermined second time period.

10. Method according to one of the preceding claims, wherein the controlled adjustment of the target speed (5) additionally takes place as a function of a vehicle mass of at least the electric bicycle (100).

11. Electric bicycle, comprising: a drive unit (1), and a control unit (50) which is configured to carry out the method according to one of the preceding claims.

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