METHOD AND DEVICE FOR OPERATING AN ELECTRIC BICYCLE

Abstract

A method for operating an electric bicycle. The method includes: detecting a mechanical load of a component of the bicycle in a load parameter set caused by a drive of the electric bicycle, ascertaining a resultant mechanical load, which results from the mechanical load of the component caused by the drive since a start of the detection of the mechanical load, based on the load parameter set, and limiting a torque provided by the drive when the resultant mechanical load exceeds a limiting value.

Claims

1. A method for operating an electric bicycle, comprising the following steps: detecting a mechanical load of a component of the bicycle in a load parameter set caused by a drive of the electric bicycle; ascertaining a resultant mechanical load, which results from the mechanical load of the component caused by the drive since a start of the detection of the mechanical load, based on the load parameter set; and limiting a torque provided by the drive when the resultant mechanical load exceeds a limiting value.

2. The method as recited in claim 1, wherein the caused mechanical load is caused using a torque provided by the drive, and a behavior of the torque is described by the load parameter set.

3. The method as recited in claim 1, wherein the load parameter set describes a frequency distribution, a torque range covered by the drive being subdivided into multiple torque intervals, and a time period, which describes how long a torque lying within the respective torque interval has been provided by the drive, being stored in the load parameter set for each of the torque intervals.

4. The method as recited in claim 3, wherein the torque intervals are identical in size, the covered torque range being subdivided in torque intervals of 5% or 10% or 20%.

5. The method as recited in claim 1, wherein the load parameter set describes a frequency, which indicates how often a torque provided by the drive lay continuously above a predefined torque threshold for longer than a predefined time interval.

6. The method as recited in claim 1, wherein the load parameter set describes a load time, which indicates how long a torque provided by the drive lay above a predefined torque threshold.

7. The method as recited in claim 1, wherein the load parameter set includes a temperature parameter, which describes at which temperature a particular torque has been provided by the drive.

8. The method as recited in claim 1, wherein the limitation of the torque provided by the drive takes place via a reduction of an assistance factor.

9. The method as recited in claim 1, wherein the ascertainment of the resultant mechanical load takes place based on the same calculation criteria that have been utilized when designing the electric bicycle.

10. A device for operating an electric bicycle, comprising: a control unit configured to: detect a mechanical load of a component of the bicycle in a load parameter set caused by a drive of the electric bicycle, ascertain a resultant mechanical load, which results from the mechanical load of the component caused by the drive since a start of the detection of the mechanical load, based on the load parameter set, and limit a torque provided by the drive when the resultant mechanical load exceeds a limiting value.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Exemplary embodiments of the present invention are described in detail below with reference to the figures.

[0026] FIG. 1 shows a flowchart of a method according to the present invention for operating an electric bicycle in one exemplary specific embodiment of the present invention.

[0027] FIG. 2 schematically shows a representation of an electric bicycle including a device for operating the electric bicycle, according to an example embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0028] FIG. 1 shows a flowchart of a method 100 for operating an electric bicycle 1. Method 100 includes a first step 101, a second step 102 and a third step 103.

[0029] In first step 101, a detection of a mechanical load of a component of bicycle 1 caused by a drive 3 of electric bicycle 1 takes place in a load parameter set. The detection of the mechanical load in the load parameter set takes place starting with a start-up of bicycle 1. For this purpose, method 100 is initiated, for example, during manufacture or during a sale of bicycle 1 by a dealer via a service interface. The component, whose mechanical load is detected in the load parameter set, is, here, for example, a component of a drive train of the bicycle, for example, gears of the bicycle. The gears of bicycle 1 are loaded primarily by a torque caused by drive 3. In order to detect the mechanical load of the component, a behavior of the torque is described by the load parameter set. A behavior of the torque in this case may be recorded in the load parameter set in different ways.

[0030] Thus, for example, the load parameter set describes a frequency distribution, a torque range covered by the drive being subdivided into multiple torque intervals and a time period being stored in the load parameter set for each of the torque intervals, which describes how long a torque present within the respective torque interval has been provided by the drive. Thus, the torque range covered by the drive, i.e., a range of 0 Nm up to the maximum available torque, is subdivided, for example, into twenty torque intervals of equal size, which subdivide the entire torque range into 5% intervals. If the electric bicycle and drive 3 are operated, it is then read out which torque is provided by the drive and this is noted for the associated torque interval. If, for example, drive 3 is operated in such a way that the drive provides 3% of the maximum possible torque for one minute, a corresponding time period of one minute is then added up in the interval from 0% to 5%. After a longer operation of the electric bicycle, a frequency distribution will result, from which it is apparent which torque values have been most frequently used. The frequency distribution indicates to what extent the component has been loaded by the torque in the given time period as of the recording of the frequency distribution.

[0031] Alternatively or in addition, the load parameter set describes a frequency, which indicates how often a torque provided by drive 3 lay continuously above a predefined torque threshold for longer than a predefined time interval. Thus, the predefined time interval is selected, for example, to be at one minute, two minutes or three minutes. The predefined torque threshold could be selected to be up to 90% of the torque maximally provided by drive 3. This means that once more than 90% of the maximally available torque is retrieved by drive 3 for longer than, for example, one minute, a counter is then incremented. The higher the counter content, the higher the resultant mechanical load of the component.

[0032] Alternatively or in addition, a load time is described by the load parameter set, which indicates how long a torque provided by the drive was present above a predefined torque threshold.

[0033] Thus, it is detected, for example, when the torque provided by drive 3 was higher than 90% of the maximally available torque. If, during an operation, the torque is above this predefined torque threshold, then a timer is activated, which adds these times together. The higher the summed-up time, the stronger the mechanical load of the component.

[0034] Alternatively or in addition, the load parameter set includes a temperature parameter, which describes at which temperature a particular torque has been provided by drive 3. Thus, it is detected, for example, which temperature drive 3 or the components of bicycle 1 exhibit when a particular torque is retrieved. If these temperatures are above or below a particular temperature threshold, this may lead to a particularly high resultant mechanical load.

[0035] As previously described, the load parameters in the load parameter set allow for a conclusion to be drawn about a resultant mechanical load of the component of the bicycle. The terms “aging” and “fatigue” and “mechanical load” are cited here in context, since a higher mechanical load typically results in a more rapid aging or fatigue of the component.

[0036] In second step 102, an ascertainment of a resultant mechanical load follows, which results from the mechanical load of the component caused by drive 3 since a start of the detection of the mechanical load. This takes place based on the load parameter set. Thus, the values stored in the load parameter set are analyzed and from this a resultant load is deduced. In the process, the time period since the start of the detection of the mechanical load is considered, i.e., typically a time period since an initial start-up of electric bicycle 1 or of drive 3. In very simple specific embodiments, this may take place, for example, by simply considering how high a counter content is, which describes how often the torque provided by the drive was continuously above the predefined torque threshold for longer than the predefined time interval. The counter content may be considered to be an equivalent for the resultant mechanical load. It is noted, however, that typically more complex calculations are used, which are available, in particular, from the field of the mechanical design of components. Thus, when designing mechanical components, it is established which mechanical loads the components must withstand over their lifetime. For this purpose, the mechanical loads, among other things, are defined. These loads also appear in the detected load parameter set. Thus, when ascertaining the resultant mechanical load, a resultant mechanical load, in particular, is ascertained, which is calculated based on the same calculation criteria, which are also utilized during a design of electric bicycle 1.

[0037] Thus, when ascertaining the resultant mechanical load, a value is calculated, which describes the load exerted on the component over an operating period of bicycle 1. If the resultant mechanical load exceeds a predefined limiting value, then third step 103 is carried out.

[0038] In third step 103, the torque provided by drive 3 is limited if the resultant mechanical load exceeds the limiting value. For this purpose, an assistance factor, in particular, is reduced. The assistance factor indicates the ratio between a rider torque provided by a rider of electric bicycle 1 and the motor torque provided for assistance by drive 3. If the assistance factor is reduced, then, given the same rider torque, a lower torque is provided by drive 3. The assistance factor is defined typically via a curve, which describes a correlation between different rider torques and different drive torques. In order to reduce the assistance factor, a slope of this curve is reduced. Thus, for example, a rider is given 10% less assistance by drive 3 over the entire bandwidth of the rider torque.

[0039] FIG. 2 shows electric bicycle 1 including a control unit 2, which is configured to carry out the method described in FIG. 1.

[0040] The load of the elements of the drive increases, in particular, with the torque delivered by the drive. For this reason, the delivered torque of drive 3, in particular, is calculated and recorded during the entire operating time.

[0041] Various characteristic values are calculated and recorded, for example, the frequency distribution: previous time period, in which 0% to 5%, 5% to 10%, 10% to 15% . . . 95% to 100% of the maximum torque has been delivered; how frequently a torque lays continuously close to the maximum value (for example, 95% to 100%) for longer than 1 minute, 2 minutes, etc., the maximum time period for which a torque >90% has been generated, for which a torque >80% has been generated, etc., and/or in which temperature ranges the torque lies (the higher the temperature, the stronger the load). From these values, a characteristic value for the cumulative load previously seen by the drive is continuously calculated in the control unit, which is also referred to here as the resultant mechanical load. When designing the drive, a value is calculated for this cumulative load, which the drive is able to reliably withstand without becoming functionally unfit (load capacity). When the cumulative load approaches the calculated load capacity, the control of the drive is changed in such a way that less torque is delivered in the future, i.e., so that the drive is no longer so severely loaded. This may occur by reduction of the maximum generated torque or by reduction of the assistance factor.

[0042] In addition to the above description, explicit reference is made to the description of FIGS. 1 and 2.