DE102023135803A1 - Drive system for an electric bicycle with a control unit and method for determining pedal power - Google Patents

Abstract

The proposed solution relates to a drive system for an electric bicycle (1), comprising a bottom bracket shaft (T) for applying a rider torque at a rider cadence for generating pedaling power for muscle-powered propulsion of the electric bicycle (1), at least one drive motor (A) for providing externally powered drive power in addition to the pedaling power, a torque unit (2) for determining the rider torque, and a frequency unit (3) for determining the rider cadence. An electronic control unit (100) is configured and provided to determine the pedaling power from the rider cadence and the rider torque.

Description

The proposed solution relates to a drive system for an electric bicycle according to the preamble of claim 1 and a method according to claim 8.

Such a drive system includes a drive motor. As is well known, the drive motor is used to provide propulsion power for the electric bicycle in addition to the pedaling power provided by the electric bicycle rider. This allows the electric bicycle rider to achieve faster propulsion with less effort.

Fundamentally, it is desirable for an electric bicycle rider to be able to document their physical performance. Against this background, the proposed solution is based on the task of providing a drive system for an electric bicycle that offers an improved user experience for the electric bicycle rider.

According to a first aspect of the proposed solution, a drive system for an electric bicycle is provided.

Such a drive system has a bottom bracket spindle for applying a rider torque at a rider cadence to generate pedaling power for muscle-powered propulsion of the electric bicycle. The rider torque can be applied to the bottom bracket spindle, for example, via a crank (possibly in conjunction with a pedal). The rider cadence (alternatively referred to as cadence) can be a measurement of the revolutions of the bottom bracket spindle per unit of time.

Furthermore, the drive system comprises at least one drive motor for providing externally powered drive power in addition to the pedaling power, a torque unit for determining the rider's torque, and a frequency unit for determining the rider's cadence. The at least one drive motor can, for example, comprise an electric motor. The frequency unit can, for example, comprise at least one magnetic sensor. Alternatively or additionally, the frequency unit can be configured and provided to determine the rider's cadence from a temporal progression of the rider's torque. This is because the rider's torque is generally at its maximum when the rider has a large lever arm available to act on the bottom bracket spindle and at its minimum when the lever arm is very small. Due to the circular movement of the pedal crank around the bottom bracket spindle during intended use of the drive system, cyclical fluctuations in the rider's torque can occur. These fluctuations have a periodicity from which the rider's cadence can be determined. For example, this can comprise one hill per half revolution of the pedal crank. The torque unit can comprise at least one torque sensor.

An electronic control unit of the drive system is configured and intended to determine pedaling power from the rider's cadence and torque. For this purpose, the electronic control unit can use values of the rider's cadence and torque that can be provided to the control unit by the frequency unit and the torque unit.

Typically, a special crank configured for power measurement is used to measure pedaling power on an electric bike or biobike. In contrast, the proposed solution enables a simple and cost-effective solution that requires no additional components. The rider's cadence and torque are also measured to calculate the drive power.

In one embodiment, the control unit is configured and provided to calculate the pedaling power from the (mathematical) product of the rider's cadence and the rider's torque. Specifically, the pedaling power can be determined from the formula 2*pi*rider's cadence*rider's torque.

In one embodiment, a display device is provided that is configured and intended to display a value of the determined pedaling power to the rider of the electric bicycle. This allows the rider to directly read their current physical performance and thus draw conclusions about their physical performance. Particularly given that using an electric bicycle requires less effort to move than a biobike, it may be desirable to be able to provide the rider with such feedback via the drive system. This allows the rider to better assess their performance and thus have an improved user experience.

In particular, the display device can be designed and provided to receive at least one vital value of the rider and to compare the value of the determined pedalling power with the at least one vital value, e.g. linked in time For example, the rider's pulse can be displayed along with the determined pedaling power. The drive system can have a vital sensor device for determining at least one vital value.

In particular, the display device can be configured and provided to display map information relating to a single or multiple rides with the electric bicycle. The value of the determined pedaling power can be displayed superimposed on a traveled route or sections thereof. For example, the value of the determined pedaling power, which was determined at a location or section of the route known by GPS positioning, can be displayed in the form of a color coding (red: high pedaling power, yellow: medium pedaling power, green: low pedaling power) superimposed on the route or the section thereof. The display device can have a GPS module for positioning.

In one embodiment, an interface is provided which is configured and intended to transmit a value of the determined pedaling power to another device. Such an additional device can be, for example, a mobile device of the rider, such as a smartphone. The interface can have, for example, a Bluetooth interface. The value of the determined pedaling power can be stored over time in order to provide the rider with a temporal progression of their pedaling power, an average value, or a cumulative value. The drive system can have a storage device for storing the values. In principle, the values can also be evaluated in a software application of the additional device.

Specifically, the value of the determined pedaling power can be used as follows. The drive system can be set up and intended to determine the start and end of an individual ride. Based on this, the rider can be provided with an average pedaling power for the individual ride. Alternatively, the rider can be provided with a value of the work performed during the individual ride (average pedaling power multiplied by the duration of the individual ride). From this, the rider can, for example, derive their calorie consumption. When providing a temporal progression of the pedaling power, the pedaling power can, for example, be averaged over one revolution of the pedal crank in order to create a data point of the progression.

In one embodiment, a calibration device is provided that is designed and configured to calibrate the determination of pedaling power. Calibration can compensate for mechanical tolerances used in the manufacture of the drive system. Furthermore, calibration can compensate for any measurement errors in determining the rider's cadence and/or torque. Calibration can be performed, for example, during the manufacture of the drive system. In principle, the drive system can be designed and configured so that calibration is performed by an electric bicycle manufacturer, a workshop, or by the rider themselves.

In one embodiment, the drive system has a filter unit that is configured and provided to filter one or more values of the rider torque based on the rider's cadence in order to determine a filtered rider torque. The filter unit can thus enable, for example, temporal filtering over at least one revolution of the bottom bracket spindle or over at least one second. In principle, the filtering can comprise at least one mathematical operation to which one or more values of the rider torque are subjected in order to reduce variability of the values over time. For example, the filtering can comprise averaging the rider torque and/or low-pass filtering. Based on the filtered rider torque, a value of the pedaling power can be determined that is representative of a route or sections thereof, such that it is suitable for display by the display device overlaid with map information.

In one embodiment, the electronic control unit has a blocking module that is configured and provided to block the determination of the pedaling power by the electronic control unit. For example, the blocking module can have a first state in which the determination of the pedaling power is permitted and a second state in which the determination of the pedaling power is blocked. The control unit can be configured and provided to make the determination of the pedaling power dependent on the state of the blocking module. Accordingly, the control unit can be configured and provided not to determine the pedaling power when the blocking module is in the second state. The rider of the electric bicycle then receives no feedback on his pedaling power from the drive system.

A locking module status can be selected by the rider, for example, as an option when purchasing the electric bike. Alternatively, the locking module status can be selected once during use of the electric bike (pay-per-use) or for each use of the pedaling power calculation (pay-per-use). For example, The state of the locking module can be selected via the interface to the additional device (e.g., a smartphone). The availability of the locking module allows for easy control of the drive system's provisioning costs and easy adaptation of the drive system to the driver's needs.

In one embodiment, an evaluation unit is provided which is configured and intended to provide one or more values of the determined pedaling power in the form of a function depending on the rotation angle of the bottom bracket spindle. The rotation angle can, for example, take the form of an angle of the pedal crank in relation to the bottom bracket spindle. Using such a function, the rider can determine whether they are achieving optimal pedaling power at each rotation angle. The function can, for example, comprise providing information for each rotation angle or angle ranges up to 5°. In particular, this can optimize pedaling behavior toward a desired smooth pedal stroke, i.e., balanced pedaling behavior for all rotation angles or angle ranges, in particular between the left and right pedal cranks. For this purpose, the pedaling power can either not be filtered at all or only over short angle ranges, such as up to 5°. Such angle ranges can be representative of the rotation angle. The rider can also be provided with the rider torque and/or pedal force as a function of the rotation angle. Based on the above values, the rider can decide how to optimize their pedaling behavior.

The provision of the value or several values of the determined pedaling power in the form of the function as a function of a rotation angle can, for example, be designed in such a way that the determined pedaling power is made available to the rider for a selected section of a journey (e.g. journey on the flat or uphill) via the rotation angle for each revolution of the pedal crank.

Additionally or alternatively, the provision of the value or multiple values of the determined pedaling power in the form of the function as a function of the rotation angle can be designed in such a way that the determined pedaling power is made available to the rider for a selected section or the entire journey by communicating the values of the pedaling power for each rotation angle (or a small angle range such as 5°, so that 72 value pairs of rotation angle and pedaling power are available for a 360° rotation) from all revolutions of the pedal crankshaft in the selected section or the entire journey.

Additionally or alternatively, the provision of the value or multiple values of the determined pedaling power in the form of the function as a function of a rotation angle can be designed in such a way that a frequency of values of the determined pedaling power over intervals of rotation angles is made available to the rider for a selected section or the entire journey (comparable to an accumulated histogram for the values of the pedaling power).

• - Aufbringen eines Fahrerdrehmoments auf eine Tretlagerwelle mit einer Fahrertrittfrequenz für eine Erzeugung einer Trittleistung für eine muskelkraftbetätigte Fortbewegung des Elektrofahrrads,
• - Bereitstellen einer fremdkraftbetätigt erzeugten Antriebsleistung zusätzlich zu der Trittleistung durch mindestens einen Antriebsmotor,
• - Bestimmen des Fahrerdrehmoments durch eine Drehmomenteinheit,
• - Bestimmen der Fahrertrittfrequenz durch eine Frequenzeinheit,
• - Ermitteln der Trittleistung aus der Fahrertrittfrequenz und dem Fahrerdrehmoment durch eine elektronische Steuereinheit.

According to a second aspect of the proposed solution, a method for determining the pedaling power of an electric bicycle rider is provided. The method comprises the following steps:

• - Applying a rider torque to a bottom bracket shaft with a rider cadence to generate pedal power for muscle-powered propulsion of the electric bicycle,
• - Providing an externally powered drive power in addition to the pedal power by at least one drive motor,
• - Determining the driver torque by a torque unit,
• - Determining the rider’s cadence by a frequency unit,
• - Determination of pedaling power from the rider's cadence and the rider's torque by an electronic control unit.

Features and advantages described in connection with the first aspect of the proposed solution may also apply to the method according to the second aspect.

The proposed solution also includes a computer program product. The computer program product has instructions that, when executed by at least one processor of an electronic control unit for a drive system of an electric bicycle, cause the at least one processor to execute a method according to the second aspect.

Furthermore, the proposed solution comprises an electric bicycle with a drive system according to the first aspect of the proposed solution.

The attached figures illustrate possible embodiments of the proposed solution.

• 1 eine schematische Ansicht eines Elektrofahrrads;
• 2 ein Schema eines Antriebssystems;
• 3 eine diagrammatische Darstellung der Trittleistung als Funktion des Umdrehungswinkels;
• 4 eine diagrammatische Darstellung der Trittleistung in Form eines akkumulierten Histogramms über dem Umdrehungswinkel;
• 5 eine kombinierte diagrammatische Darstellung der Trittleistung als Funktion des Umdrehungswinkels und Histogramme von Werten der Trittleistung für ausgewählte Intervalle des Umdrehungswinkels; und
• 6 eine diagrammatische Darstellung der Trittleistung als Funktion des Umdrehungswinkels in Form von Maximalwerten, Mittelwerten und Minimalwerten.

Here we show:

• 1 a schematic view of an electric bicycle;
• 2 a diagram of a drive system;
• 3 a diagrammatic representation of pedal power as a function of rotation angle;
• 4 a diagrammatic representation of pedaling power in the form of an accumulated histogram over the rotation angle;
• 5 a combined diagrammatic representation of pedal power as a function of rotation angle and histograms of pedal power values for selected intervals of rotation angle; and
• 6 a diagrammatic representation of pedaling power as a function of rotation angle in the form of maximum, average and minimum values.

1 shows a schematic view of an electric bicycle 1 with a front wheel 10 and a rear wheel 11. The rear wheel 11 is connected via a transmission member 12 (e.g. a chain) to a drive motor A, which is designed to transmit pedaling power generated thereby to the rear wheel 11 via the transmission member 12. The pedaling power can be generated by a rider on a bottom bracket shaft T by applying a bicycle torque at a rider cadence. This enables muscle-powered movement of the electric bicycle 1. In this case, the rider can generate the rider torque via pedal cranks K with pedals P on the bottom bracket shaft T.

2 shows a diagram of a drive system for an electric bicycle. The drive system has a bottom bracket shaft T, via which a rider torque with a rider cadence can be applied. The rider torque is determined using a torque unit 2. The rider cadence is determined using a frequency unit 3. An electronic control unit 100 is configured and provided to determine a pedaling power from the rider cadence and the rider torque. The determination can comprise calculating a mathematical product of the rider torque and the rider cadence.

The control unit 100 includes an optional filter unit 101, which is configured and provided to filter one or more values of the rider torque based on the rider's cadence in order to determine a filtered rider torque. The filtered rider torque may, for example, be better suited for determining pedaling power.

The control unit 100 further comprises a blocking module 102, which is configured and provided to block the determination of the pedaling power. For example, the control unit 100 can check, each time the pedaling power is determined, whether the blocking module 102 is in a state that prohibits the determination or provision of a value of the determined pedaling power (e.g., to a display device 5). The state of the blocking module 102 can be changed by a user of the drive system, so that the user can decide with the aid of the blocking module 102 whether or not to use the function for determining the pedaling power.

The drive system further comprises a calibration device 4, which is configured and intended to calibrate the determination of pedaling power. This allows tolerances in the manufacturing of the drive system and/or measurement errors in the determination of the rider's torque and/or rider's cadence to be compensated.

A value of the determined pedaling power is made available by the control unit 100 to the display device 5 and/or an interface 6. The display device 5 can, for example, comprise a "human machine interface" (HMI), which is suitable for being arranged on the electric bicycle 1 in such a way that the rider can read a displayed value of the pedaling power from it when using the electric bicycle 1. This allows the rider to immediately determine their pedaling power while using the electric bicycle 1. The interface 6 can, for example, comprise a Bluetooth interface. The drive system can be connected via the interface, for example, to another device such as a mobile device of the rider. The mobile device can, for example, receive a series of values of the determined pedaling power via the interface 6. A software application of the mobile device can be configured and provided to evaluate the series of values so that the rider of the electric bicycle 1 can derive their physical performance from the evaluation.

Furthermore, an evaluation unit 7 is provided which is designed and intended to provide a value of the determined pedaling power in the form of a function depending on an angle of rotation of the bottom bracket shaft T.

The 3 to 6 show exemplary diagrams for providing values of the determined pedal power in the form of functions depending on the angle of rotation.

3 shows values of the determined pedal power (in any units; au) in the form of functions over the angle of rotation in degrees. The values of the determined pedal power are for a full 360° rotation of the bottom bracket spindle T. The diagram shows a total of six functions, whose curves differ significantly. For a rider's desired smooth pedal stroke, the functions are closer together and symmetrical by 180° (M-shaped). With a symmetrical design of the functions, the rider can achieve the same pedaling power on the left crank as on the right crank.

In order to make it easier for the rider to adapt his pedalling behaviour on the basis of the determined pedalling power, the evaluation unit 7 can be set up and provided to provide the values of the determined pedalling power in the form of an accumulated histogram for which 4 shows an example diagram. In it, the rotation angle is divided into a number of intervals with a size of less than 15°. For each of these intervals, a frequency of a total of five ranges of pedaling power is indicated by different hatching. The diagram is based on the examples shown in 3 The functions shown. This shows that the diagonally hatched areas of combinations of pedaling power ranges and angle intervals occur particularly frequently. The vertically hatched areas are at least more frequent than average. The white areas have a lower frequency or do not occur at all.

With the desired pedaling behavior (round pedaling), the pedaling power for each rotation of the bottom bracket spindle T is the same or at least very similar at the same rotation angle. Under such circumstances, the areas with the highest frequency should form a structure that is symmetrical by 180° (M-shaped). By displaying the pedaling power in the form of an accumulated histogram, the rider can adjust their pedaling behavior particularly easily by striving to increase the number of hatched areas and arrange them on an M-shaped function over the rotation angle (thus condensing the frequency of the pedaling power into a few areas). The achievement of a shape corresponding to a desired pedaling behavior can be indicated to the rider in the form of an indication signal by the display device 5 (e.g., an acoustic signal and/or illumination of the bright areas).

5 shows a combined diagrammatic representation of pedal power as a function of rotation angle and histograms of pedal power values for selected intervals of rotation angle.

6 shows a diagrammatic representation of the pedaling power as a function of the rotation angle in the form of maximum values, average values and minimum values.

For the function of the maximum values (function with the highest values in the diagram), a series of functions of the determined pedal power (for example, the six functions of the 3 ) the maximum values are displayed for each value of the rotation angle.

For the function of the mean values (function with the most mean values in the diagram), a series of functions of the determined pedal power (for example, the six functions of the 3 ) the mean values are displayed for each value of the rotation angle.

For the function of the minimum values (function with the lowest values in the diagram), a series of functions of the determined pedal power (for example, the six functions of the 3 ) the minimum values are displayed for each value of the angle of rotation. A smooth pedaling behavior is present in particular when the functions are close together with regard to pedaling power and are designed symmetrically by 180°. The rider can easily optimize his pedaling behavior by striving to reduce the differences between the three functions (or at least between minimum values and maximum values). If the difference falls below a predetermined limit (e.g. less than 5% difference in all values) the rider can be informed by the display device 5 in the form of an indication signal (e.g. an acoustic signal and/or the functions lighting up).

List of reference symbols

1

electric bike

10

front wheel

100

Control unit

101

filter unit

102

Locking module

11

Rear wheel 12 transmission link

2

Torque unit

3

Frequency unit

4

Calibration device

5

Display device

6

interface

7

Evaluation unit

A

drive motor

K

crank

P

pedal

T

bottom bracket spindle

Claims (11)

Drive system for an electric bicycle (1), with - a bottom bracket shaft (T) for applying a rider torque with a rider cadence for generating a pedaling power for muscle-powered movement of the electric bicycle (1), - at least one drive motor (A) for providing an externally powered drive power in addition to the pedaling power, - a torque unit (2) for determining the rider torque and - a frequency unit (3) for determining the rider cadence, characterized by - an electronic control unit (100) which is set up and provided to determine the pedaling power from the rider cadence and the rider torque. Drive system according to Claim 1 , characterized in that the control unit (100) is designed and provided to calculate the pedaling power from the product of the rider's pedaling frequency and the rider's torque. Drive system according to one of the Claims 1 and 2 , characterized by a display device (5) which is designed and provided to display a value of the determined pedaling power to a rider of the electric bicycle (1). Drive system according to one of the Claims 1 until 3 , characterized by an interface (6) which is designed and provided to transmit a value of the determined pedal power to another device. Drive system according to one of the preceding claims, characterized by a calibration device (4) which is designed and provided to calibrate the determination of the pedaling power. Drive system according to one of the preceding claims, characterized by a filter unit (101) which is designed and provided to filter one or more values of the driver torque on the basis of the driver's cadence in order to determine a filtered driver torque. Drive system according to one of the preceding claims, characterized by a blocking module (102) which is designed and provided to block the determination of the pedaling power by the electronic control unit (100). Drive system according to one of the preceding claims, characterized by an evaluation unit (7) which is designed and provided to provide one or more values of the determined pedaling power in the form of a function as a function of an angle of rotation of the bottom bracket shaft (T). Method for determining a pedaling power of a rider of an electric bicycle (1), comprising the steps of: - applying a rider torque to a bottom bracket shaft (T) with a rider cadence for generating a pedaling power for muscle-powered movement of the electric bicycle (1), - providing an externally powered drive power in addition to the pedaling power by at least one drive motor (A), - determining the rider torque by a torque unit (2), - determining the rider cadence by a frequency unit (3), characterized by - determining the pedaling power from the rider cadence and the rider torque by an electronic control unit (100). Computer program product, comprising instructions which, when executed by at least one processor of an electronic control unit (100) for a drive system of an electric bicycle (1), cause the at least one processor to carry out a method according to Claim 9 to execute. Electric bicycle (1) with a drive system according to one of the Claims 1 until 8 .

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