WO2020079575A1

WO2020079575A1 - Control device and control method for an electric motor of an electric bicycle

Info

Publication number: WO2020079575A1
Application number: PCT/IB2019/058761
Authority: WO
Inventors: Antonius Georg ROSSBERGER
Original assignee: Tq-Systems Gmbh
Priority date: 2018-10-15
Filing date: 2019-10-15
Publication date: 2020-04-23

Abstract

The invention relates to a device and method for determining a motor support of an electric motor comprising a first strain gauge element in a first region of a crank spindle receiving region and a second strain gauge element in an opposing second region of the crank spindle receiving region. An evaluation electronics system, which is connected to the first strain gauge element and to the second strain gauge element, is designed to receive first and second signals from the first and the second strain gauge element, to determine a first reference value of the first signal, to determine a second reference value of the second signal, and to deactivate the motor support on the basis of the first reference value and the second reference value.

Description

CONTROL DEVICE AND CONTROL METHOD FOR AN ELECTRIC MOTOR OF AN ELECTRIC BIKE

The present description discloses a device for driving an electric motor for motor assistance of a pedal torque and a method for driving the electric motor. In another aspect, the present disclosure discloses a bottom bracket for an electric bicycle, the bottom bracket having a deformation sensor.

In particular, the present description discloses a device for determining a motor support of an electric bicycle for supporting a pedal torque provided by a driver of the electric bicycle. Motor support is to be deactivated in particular when the driver does not provide any pedal torque for seduction. This is the case, for example, when a dead center area is reached within a pedaling cycle, but also, for example, when a rider holds the pedals in one position, steps backwards or steps more slowly than is required to drive the bicycle.

The device has a bottom bracket with a pedal shaft receiving area, such as, for example, a bottom bracket housing, an area of the bicycle frame or a cylindrical receiving area of a load cell.

The pedal shaft receiving area has a first strain measuring element in a first area of the pedal shaft receiving area and a second strain measuring element in a second region of the pedal shaft receiving area, the second area being opposite the first area with respect to the bottom bracket receiving area. The opposite position can also be defined with respect to a central axis of the bottom bracket receiving area or with respect to a central axis of a pedal shaft mounted therein.

A strain gauge element can in particular be provided by a strain gauge who. The strain gauge element can also be provided by other types of displacement or strain sensors, such as magnetic, magnetostrictive or capacitive sensors. Furthermore, the device has evaluation electronics which are connected to the first strain measuring element and to the second strain measuring element.

The evaluation electronics are set up to receive a first signal from the first strain measuring element and a second signal from the second strain measuring element, wherein the signals can in particular be voltage signals or generally electrical signals. Furthermore, the evaluation electronics are set up to determine a first reference value or zero point value of the first signal and to determine a second reference value of the second signal. These reference values can correspond, for example, to a position of the pedal shaft in which a pedal shaft does not exert any additional compressive force on the first strain element or on the second strain measuring element. This corresponds to a situation in which a rider does not drive the bicycle through the pedals.

Furthermore, the evaluation electronics are set up to deactivate the motor support on the basis of the first reference value and the second reference value and then to activate it again. The activation can be done in particular by sending deactivation or activation signals. The above-mentioned determination of a reference value can take place, for example, by measuring the corresponding first or second signal and comparing it with a previously determined reference value, and determining whether the reference value is accepted or reached.

According to the method, a drift of the reference value is taken into account. For this purpose, the reference values are determined immediately at the time of deactivation or activation of the motor and / or by means of a previous calibration, which can be carried out repeatedly in order to take into account a drift of the reference value.

According to a further embodiment, the evaluation electronics are set up to deactivate the motor support if the signal of the first strain measuring element is essentially constant and the signal of the second strain measuring element is essentially constant. The signal is essentially constant over a period of time if it only assumes values in a predefined range around a constant value, wherein the predefined range can be, for example, 5% of a maximum amplitude of the signal. In the case of a dead center area, the time period can also comprise fractions of a second, and in particular can be in the range of a few tenths or hundredths of a second. For example, the time period can comprise 10% of a pedal cycle that lasts 3 seconds, that is 0.3 seconds.

Furthermore, the evaluation electronics according to this embodiment is set up to activate the motor support when the signal of the second strain measuring element leaves a predefined range around the value that it assumed when the motor support was deactivated, or when the signal of the first strain measuring element leaves a predefined range around the value that it assumed at the beginning of the deactivation period. As an additional condition, it can be checked whether the value in a predefined cattle with respect to the course of the signal value over time. The predefined direction can refer in particular to an ascending or a descending direction.

According to a further embodiment, the evaluation electronics are set up to deactivate the motor support when the signal of the first strain measuring element reaches the first reference value and the signal of the second strain measuring element reaches the second reference value, and to activate the motor support when the signal of the second strain measuring element leaves the second reference value or when the signal of the first strain measuring element leaves the first reference value.

As additional conditions, it can also be checked whether the signal remains in a predefined range around the reference value and / or whether the signal leaves a predefined range around the reference value in a predefined direction.

According to a further embodiment, which provides a calibration of the reference values, the evaluation electronics is set up to determine the first reference value and the second reference value, in which the evaluation electronics checks whether within a predefined measuring range, i.e. an assumed range, possible zero or Reference values, during a pedaling cycle a signal of the first strain measuring element is essentially constant in sections and at the same time a signal of the second strain measuring element is substantially constant. In this case, the signal is essentially constant in sections if it changes by no more than a fraction, for example 5%, of a maximum amplitude within a predetermined time period, the predetermined time period being on the order of tenths or hundredths of a second or even longer.

If this is the case, the evaluation electronics stores the constant value of the first signal as the first reference value and the constant value of the second signal as the second reference value, which can be done, for example, in a computer-readable memory of the evaluation electronics after A / D conversion of the signal.

According to a further embodiment, the pedal shaft receiving area furthermore has a third strain measuring element in a third area of the pedal shaft receiving area and a fourth strain measuring element in a fourth area of the pedal shaft receiving area. The fourth area is opposite to the third area with respect to the pedal wave receiving area. As a result, the reference values can be determined more precisely and / or further reference values of the sensor signals of the strain measuring elements can be determined. Can continue the four strain gauges also better determine a direction of force of a force on the pedal shaft and thus a torque on the pedal shaft.

According to this exemplary embodiment, the evaluation electronics are further configured to receive a third signal from the third strain measuring element and a fourth signal from the fourth strain measuring element, to determine a third reference value of the third signal, and to assign a fourth reference value of the fourth signal determine.

Furthermore, the evaluation electronics are set up to deactivate the motor support on the basis of the first reference value, the second reference value, the third reference value and the fourth reference value.

According to a further exemplary embodiment, the evaluation electronics are set up to deactivate the motor support when the signal of the third strain measuring element is essentially constant and the signal of the fourth strain measuring element is essentially constant. Furthermore, the evaluation electronics are set up to activate the motor support when the signal of the third strain measuring element leaves a predefined range by the value that it assumed when deactivating the motor support, or when the signal of the fourth strain measuring element passed a predefined range leaves the value it assumed at the start of the deactivation period. Furthermore, the evaluation electronics can check the conditions mentioned above in relation to the first or second signal.

According to a further exemplary embodiment, evaluation electronics are set up to deactivate the motor support when the signal of the third strain measuring element reaches the third reference value and the signal of the fourth strain measuring element reaches the fourth reference value. The evaluation electronics is also set up to activate the motor support when the signal of the third strain measuring element leaves the third reference value or when the signal of the fourth strain measuring element leaves the fourth reference value. Furthermore, the evaluation electronics can check the conditions mentioned above in relation to the first or second signal.

According to a further exemplary embodiment, the evaluation electronics are set up to determine the third reference value and the fourth reference value in each case, in which the evaluation electronics checks whether a signal of the third strain measuring element is essentially constant in sections within a predefined measuring range during a wearing cycle at the same time, a signal from the fourth strain measuring element is constant, and if so, store the constant value of the third signal as the third reference value and the constant value of the fourth signal as the fourth reference value.

According to a further exemplary embodiment, according to which a support power of the electric motor is determined, the evaluation electronics is also set up to determine a sum of a pedal torque and a chain torque from the first signal, the second signal, the third signal and the fourth signal. Furthermore, the above-mentioned device according to this exemplary embodiment comprises an angle sensor for determining a pedal shaft angle and a current sensor for determining a motor current supplied to the electric motor.

The evaluation electronics is set up to determine a support power from the sum of the pedal torque and the chain torque, the pedal shaft angle, and the motor current and to control the electric motor, to provide the support power in order to amplify or support a driver's pedal torque. In this case, for example, a support torque can be determined first and from this the support power of the electric motor.

According to an alternative embodiment, the device further comprises a torque sensor for determining a sum of pedal torque and chain torque, an angle sensor for determining a pedal shaft angle and a current sensor for determining a motor current supplied to the electric motor. The torque sensor can in particular be provided by the strain gauge elements.

The evaluation electronics is also set up to determine a support power from the sum of the pedal torque and the chain torque, the pedal shaft angle, and the motor current and to control the electric motor to provide the support power.

Furthermore, the present description discloses an electric bicycle with the above-mentioned device. The electric bicycle has control electronics of the electric motor, which is set up to communicate with the device, which can be done via signal lines or wirelessly. Furthermore, the electric bicycle has the above-mentioned electric motor, the electric motor being connected to the control electronics and being mechanically connected, for example via a gear and a chain, to an driven wheel of the electric bicycle, and a pedal shaft, which is in the pedal shaft receiving area is stored. In another aspect, the present disclosure discloses a computer-implemented method for determining a motor support of an electric motor of an electric bicycle in order to support a pedal torque provided by a driver of the electric bicycle.

The electric bicycle has a bottom bracket with a pedal shaft receiving area, the pedal shaft receiving area having a first strain measuring element in a first area of the bottom bracket housing and a second strain measuring element in a second area of the pedal shaft receiving area, the second area being the first Area opposite the bottom bracket receiving area.

The method has the following steps: receiving a first signal from the first strain measuring element and a second signal from the second strain measuring element, determining a first reference value of the first signal,

Determining a second reference value of the second signal, and deactivating the motor support on the basis of the first reference value and the second reference value or activating the motor support on the basis of the first and the second reference value, the activation and deactivation being able to take place in particular by sending deactivation or activation signals .

According to a further exemplary embodiment, the method also has the following steps: deactivating the motor support when the signal of the first strain measuring element is essentially constant and the signal of the second strain measuring element is essentially constant. Furthermore, the motor support is activated when the signal of the second strain measuring element leaves a predefined range around the value that it assumed when deactivating the motor support, or when the signal of the first strain measuring element passed a predefined range around the value it accepted at the beginning of the deactivation period.

According to a further exemplary embodiment, the method further comprises the following steps: deactivating the motor support when the signal of the first strain measuring element reaches the first reference value and the signal of the second strain measuring element reaches the second reference value, and activating the motor support if that Signal of the second strain gauge leaves the second reference value or when the signal of the first strain gauge leaves the first reference value. According to a further exemplary embodiment, which provides a calibration of the reference values, the method also has the following steps: determining the first reference value and the second reference value, the determination of the first reference value and the second reference value comprising the following steps.

Check whether a signal of the first strain-measuring element is essentially constant in sections and, at the same time, a signal of the second strain-measuring element is substantially constant in sections, and if so, within a predefined measuring range during a wearing cycle. Storing the constant value of the first signal as the first reference value, and storing the constant value of the second signal as the second reference value.

According to a further exemplary embodiment, the pedal shaft receiving area further has a third strain measuring element in a third area of the pedal shaft receiving area and a fourth strain measuring element in a fourth area of the pedal shaft receiving area, the fourth area relating to the pedal shaft Across the exposure area.

According to this exemplary embodiment, the method further comprises the following steps. Receiving a third signal from the third strain gauge and a fourth signal from the fourth strain gauge, determining a third reference value of the third signal, determining a fourth reference value of the fourth signal, and deactivating motor assistance based on the first reference value, the second reference value , the third reference value and the fourth reference value the motor support.

According to a further exemplary embodiment, the method further has the following steps: deactivating the motor support when the signal of the third strain measuring element is essentially constant and the signal of the fourth strain measuring element is substantially constant. Activation of the motor support if the signal of the third strain measuring element leaves a predefined range by the value that it assumed when the motor support was deactivated, or if the signal of the fourth strain measuring element left a predefined range by the value that it had at the start who has accepted the deactivation period.

According to a further exemplary embodiment, the method also has the following steps: Deactivating the motor support when the signal of the third strain measuring element reaches the third reference value and the signal of the fourth strain measuring element reaches the fourth reference value. Activate motor support when the signal from the third Strain-measuring element leaves the third reference value or when the signal of the fourth strain-measuring element leaves the fourth reference value.

According to a further exemplary embodiment, the method also has the following steps: determining the third reference value and the fourth reference value, the determination of the third reference value and the fourth reference value comprising the following steps: checking whether a signal of the third strain gauge element is essentially constant in sections and at the same time a signal of the fourth strain gauge element is substantially constant in sections. If so, the constant value of the third signal is stored as the third reference value and the constant value of the fourth signal is stored as the fourth reference value.

According to a further exemplary embodiment, the electric bicycle also has an angle sensor for determining a pedal shaft angle and a current sensor for determining a motor current supplied to the electric motor.

The method further comprises the following steps: determining a sum of a pedal torque and a chain torque from the first signal, the second signal, the third signal and the fourth signal, determining an assist power from the sum of the pedal torque and the chain torque, the pedal shaft Angle, and the motor current, and driving the electric motor to provide the support power.

According to a further exemplary embodiment, the electric bicycle also has a torque sensor for determining a sum of pedal torque and chain torque, and an angle sensor for determining a pedal shaft angle and a current sensor for determining a motor current supplied to the electric motor.

According to this exemplary embodiment, the method also has the following steps: determining an assistance power from the sum of the pedal torque and the chain torque, the pedal shaft angle, and the motor current, an assistance power, and driving the electric motor to provide the assistance power.

Bottom brackets for bicycles are known. There is a need to improve the known bottom bracket for bicycles in terms of their robustness and functionality. According to a further aspect of the present description, a novel bottom bracket for a bicycle is provided. The bottom bracket includes a left sleeve nut, a bottom bracket shell, a right sleeve nut and an optional connecting sleeve for mounting the bottom bracket on a bicycle pedal shaft.

The directional information, such as "left" or "right", are directions from the perspective of a person riding a bicycle. From this perspective, for example, a conventional chain bicycle would always have the bicycle chain arranged “on the right”.

The bottom bracket has a left sleeve nut, a bottom bracket shell and a right sleeve nut, the bottom bracket shell has a left bearing seat with a left roller bearing and a right th bearing seat with a right roller bearing. The left bearing seat and / or the right bearing seat have at least one deformation sensor, wherein an inner ring of the left roller bearing and / or an inner ring of the right roller bearing is or are connected with at least one position sensor which determines its position with respect to the bottom bracket housing telt. Furthermore, there is an evaluation and transmission circuit for evaluating the electrical signals supplied by the deformation sensor and / or from the position sensor and for preferably wirelessly transmitting the data obtained by the evaluated signals. The evaluation and transmission circuit has an energy store for storing electrical energy supplied by the position sensor for the operation of the deformation sensors and / or the evaluation and transmission circuit.

The bottom bracket shell includes a left bearing seat and a right bearing seat. A left roller bearing is arranged between the left bearing seat and the connecting sleeve. A right roller bearing is arranged between the right bearing seat and the connecting sleeve.

The bottom bracket further comprises at least one sensor, in particular for detecting at least one operating parameter of the bicycle, as well as an evaluation and transmission circuit, which is designed to evaluate electrical signals supplied by the at least one sensor and to send data received by the evaluated signals to at least one receiver send, especially to transmit wirelessly via an antenna.

The evaluation and transmission circuit can in particular have a reception interface for receiving and digitizing the signals supplied by the at least one sensor. Furthermore, the evaluation and transmission circuit can include a computing unit with a memory unit and with a processor, in particular for evaluating the digitized signals, and a Include transmitter unit for sending evaluation results to the at least one receiver.

Both portable devices, for example sports watches or smartphones, and devices mounted on the bicycle, such as monitors, bicycle computers or the like, can be used as receivers. act.

In particular, the receivers can receive already evaluated results of the signal evaluation carried out by the evaluation and transmission circuit for visualization or for further processing in a format that can be read by the receivers.

The at least one sensor and the evaluation and transmission circuit can be arranged essentially entirely within the bottom bracket housing. These components are protected by the arrangement within the bottom bracket shell, so that the impairment of their functionality by external influences can be suppressed or reduced.

The evaluation and transmission circuit can have a rechargeable battery. The evaluation and transmission circuit can be designed to charge the rechargeable battery using the electrical signals supplied by the at least one sensor. The electrical signals supplied by at least one sensor can thus not only serve to record operating parameters of the bicycle, but also as an energy source for the evaluation and transmission circuit, in which the energy contained in the sensor signals is used at least partially to charge the rechargeable battery.

The at least one sensor can in particular comprise at least one strain gauge.

The strain gauges are suitable for detecting mechanical deformations. In particular, mechanical deformations of parts of the bottom bracket can be detected with a strain gauge, from which conclusions can be drawn about the mechanical forces developed in the bottom bracket.

The at least one strain gauge can be arranged in the bottom bracket in different ways. In particular, the left bearing seat and / or the right bearing seat of the bottom bracket housing can have at least one flat area directed perpendicularly with respect to the connecting sleeve, wherein the at least one strain gauge can be arranged on the at least one flat area. The vertical arrangement of the strain gauge is particularly suitable for radial or vertical deformations of the pedal shaft to determine flat areas of the bearing seats and thus the corresponding radial forces to which the flat areas of the bearing seats are exposed.

In some versions, several strain gauges are used, which are in particular evenly distributed around the circumference of the left and / or right bearing seat. Due to the even distribution of the strain gauges around the circumference of a bearing seat, the radial distribution of forces around the circumference of the bearing seat and thus more complete information about the mechanical stress on the bearing seat can be obtained.

In some embodiments, at least one strain gauge is located only on the left bearing seat. On the basis of the measurement signals supplied by the at least one strain gauge, in particular on the basis of experimental measurements, force distribution can also be determined in other areas of the bottom bracket, in particular in the right-hand bearing seat. In this way, savings can be made on the strain gauges.

In some versions of the bottom bracket, the strain gauges are arranged on both bearing seats so that the mechanical deformations or the forces developed in the bearing seats can be determined directly on both sides and thus more precisely.

The at least one sensor can comprise at least one encoder arranged within the bottom bracket housing, which has a first encoder part fastened on the inside on the inside of an outer wall of the bottom bracket housing and a second encoder part fastened on the connecting sleeve relative to the first encoder part. The second encoder part can comprise a magnet, in particular a permanent magnet, and the first encoder part can comprise a coil for detecting electromagnetic fields generated by the magnet.

In operation, the first encoder part, which is attached to the outer wall of the bottom bracket shell, circles the second encoder part, which is attached to the connecting sleeve, so that the magnet of the second encoder part always on the coil of the first encoder part drives past again. Due to electromagnetic induction, moving the magnet past the coil induces an alternating current in the coil, which is conducted to the evaluation and transmission circuit via an appropriate electrical connection.

On the basis of the electrical signals supplied by the encoder to the evaluation and transmission circuit, various operating parameters, in particular the speed and speed of the pedal shaft, acceleration, speed and the current crank position of the bicycle can be determined. The encoder or the coil and the magnet can be dimensioned such that the signals generated by the encoder can be used to charge the rechargeable battery by the evaluation and transmission circuit. The encoder can thus be used both for generating signals for the evaluation and as an energy source for the evaluation and transmission circuit, so that no further, in particular external, energy sources are required for the operation of the evaluation and transmission circuit.

The bottom bracket can be made essentially watertight. In particular, the left roller bearing and the right roller bearing can be designed as a waterproof roller bearing or as a waterproof ball bearing. Due to the watertight design of the left and right roller bearings, the watertightness of the bottom bracket can be easily achieved without special side seals. In some implementations, the outer wall of the bottom bracket housing has transmission holes that are essentially permeable to electromagnetic signals. The transmitter holes reduce the electromagnetic shielding for the signals sent by the evaluation and transmission circuit, in particular when the antenna of the evaluation and transmission circuit is completely inside the bottom bracket shell, so that the receiver or receivers receive the evaluation - and transmission circuit can better receive data sent. The transmission holes can be sealed with seals that are permeable to electromagnetic signals, in particular made of plastic, which is sealed in a water-tight manner.

In some versions, the left sleeve nut and the right sleeve nut are each provided with an external thread for screwing into the corresponding internal thread of a frame tube of a bicycle frame. The bottom bracket can be easily installed in the frame tube using the external threads of the sleeve nuts. The bottom bracket is held from the left and right by the sleeve nuts screwed into the frame tube, so that a robust connection is created between the bicycle frame and the bottom bracket.

In an alternative embodiment of the bottom bracket, the bottom bracket housing has an external thread at both ends, the left and right sleeve nuts having an inside thread corresponding to the outside threads of the bottom bracket housing, so that the bottom bracket is inserted into a frame tube and can be easily attached with sleeve nuts from both sides can. Such a design of the bottom bracket can be used to attach the bottom bracket

Frame tubes, which have no internal thread, are used, whereby a robust positive connection between the frame tube and the bottom bracket is created. The evaluation and transmission circuit can be designed to wirelessly send and / or receive signals according to one of the protocols that can be used or used for wireless communication, in particular standardized protocols. The use of the protocols used, particularly standardized, for wireless communication allows data to be exchanged smoothly with external devices, such as smartphones or sports watches.

The evaluation and transmission circuit can be designed to determine the power introduced by the cyclist on the basis of the signals supplied by the at least one sensor, in particular the at least one encoder or the at least one strain gauge. The performance brought in by the cyclist represents important information which can help the cyclist to adapt or optimize his driving behavior taking into account the determined performance. The power introduced by the cyclist can be determined on the basis of a correlation between the power and the signals supplied by the at least one sensor, which is determined in advance, in particular on a measurement setup. In particular, the bottom bracket can be exposed to different operating conditions during the measurements on the measurement setup, the signals supplied by one or more strain gauges or by one or more encoders being recorded and analyzed. In particular, a correlation between the strain gauge signals and the power at different speeds can be determined and saved as a data field in the memory unit of the evaluation and transmission circuit, which can be accessed by the processor of the evaluation and transmission circuit when determining the current cyclist line.

A bicycle is also provided. The bicycle has a bicycle frame with a bottom bracket tube. A bottom bracket according to one of the designs described here is arranged in the bottom bracket tube. A bicycle of this type has the advantage that it comprises a robust bottom bracket with increased functionality, so that operating parameters can be comprehensively and conveniently monitored during operation.

The subject of the description is explained in more detail below with reference to the figures below. Here shows 1 shows a schematic cross-sectional view of a bottom bracket according to an exemplary embodiment,

2 shows a schematic cross-sectional view of the bottom bracket according to the embodiment of FIG. 1 during the installation of the bottom bracket,

Fig. 3 is a schematic cross-sectional view of a bottom bracket according to another

Embodiment,

4 is a perspective partial view of a bottom bracket seen from the drive side,

5 is a top view of the bottom bracket of FIG. 4 seen from the drive side, FIG. 6 is a top view of the bottom bracket of FIG. 4 seen from the driven side, FIG. 7 is a cross-sectional view of the bottom bracket along the cross-sectional line A-A of FIG

Fig. 5,

8 is a side view of the bottom bracket,

9 is a perspective view of the bottom bracket seen from the driven side, FIG. 10 is a top view of the bottom bracket seen from the driven side,

11 is a cross-sectional view taken along section line A-A of FIG. 27.

12 is a cross-sectional view taken along section line B-B of FIG. 27;

13 shows a force conversion of a pedal force into a torque on a pedal shaft of a bicycle,

14 shows the force relationships of FIG. 13 in further detail,

15 shows an arrangement of the bottom bracket of FIG. 4 on a pedal shaft,

16 shows a further arrangement of the bottom bracket of FIG. 4 on the pedal shaft, FIG. 17 shows a further arrangement of the bottom bracket of FIG. 4 on the pedal shaft, FIG. 18 shows a strain gauge

19 shows characteristics of two different strain gauges,

20 shows an arrangement with two strain gauges in a half bridge, FIG. 21 shows an arrangement with four strain gauges in a full bridge, FIG. 22 shows an effect caused by a bearing play,

23 shows the effect of 20 in more detail,

24 shows a first pair of force-displacement characteristics for a pedal arrangement with two strain gages, and

25 shows a second pair of force-displacement characteristics for a pedal arrangement with two strain gauges. In the following description, details are explained to illustrate the embodiments of the description. However, it is clear to the person skilled in the art that the exemplary embodiments can also be implemented without such details. 1 shows a schematic cross-sectional view of a bottom bracket according to an exemplary embodiment in an installed state. The bottom bracket 1 of FIG. 1 comprises a left sleeve nut 2, a bottom bracket housing 3, a right sleeve nut 4 and a connecting sleeve 5.

The bottom bracket 1 is provided with a pedal shaft 35 and in a bottom bracket tube 7 of a bicycle frame 6, the left sleeve nut 2 is screwed from the left into the bottom bracket tube 7 of the driving wheel frame 6, and the right sleeve nut 4 from the right gerrohr in the bottom bracket 7 of the bicycle frame 6 is screwed. The pedal shaft 35 has an essentially smooth region 36 and two end regions 37, which are designed as pedal crank seats 38. The connecting sleeve 5 is arranged in the central region 35 of the pedal shaft 35.

The bottom bracket 1 comprises a left roller bearing 45, a right roller bearing 46, a left bearing seat 90 and a right bearing seat 91, the left roller bearing 45 between the left bearing seat 90 and the connecting sleeve 5 and the right roller bearing 45 between the right bearing seat 91 and the connecting sleeve 5 is arranged. In the exemplary embodiment in FIG. 1, the roller bearings 45, 46 are designed as ball bearings. The left-hand bearing seat 90 is provided on the inside with four strain gauges 92, which are designed to measure mechanical loads on the left-hand bearing seat 90 from the pedal shaft 35.

In the bottom bracket housing 3 there is also an encoder 8, which has a first encoder part 9 with an encoder coil (not shown) and a second encoder part 10 with an encoder magnet (not shown). The first encoder part 9 is attached to an inner wall of the bottom bracket shell 3. The second encoder part 10 is fastened on the connecting sleeve 5 opposite the first encoder part 9.

In the bottom bracket housing 3, an evaluation and transmission circuit 11 is arranged, which is connected via electrical connections 12 and 13 to the strain gauge 92 or to the first encoder part 9. The output and transmission circuit 11 has an antenna 14 for transmitting or receiving electromagnetic signals.

The bottom bracket shell 3 has a substantially cylindrical outer wall 15 with recesses 16 or transmission holes. Because of the measuring electronics housed in the bottom bracket housing 3 and because of the essentially cylindrical shape of the bottom bracket housing 3, the bottom bracket housing is also referred to as a load cell or load cell. In the exemplary embodiment in FIG. 1, the left sleeve nut 2 and the right sleeve nut 4 have external threads 20, with which the left sleeve nut 2 and the right sleeve nut 4 can be screwed into corresponding left and right internal threads 21 of the frame tube 7.

The bottom bracket 1 can be easily assembled and mounted on a bicycle.

In a first step, the bottom bracket shell 3 is provided, at least one side of the bottom bracket shell 3 being left open. By leaving the side of the bottom bracket shell 3 open, the sensors can be equipped with the strain gauge 92, the encoder 8, the evaluation and transmission circuit 11 and the electrical connections 12, 13 in a subsequent step, whereupon the left side of the bottom bracket housing ses 3 can be closed. In the exemplary embodiment in FIG. 1, the right-hand bearing seat 91 is only attached to the bottom bracket housing 3 after the bottom bracket housing 3 has been fitted with the inner elements. In the exemplary embodiment in FIG. 1, the right bearing seat 91 is welded to the outer wall 15 of the bottom bracket housing 3, which can be seen in FIG. 1 by the weld seam 25.

In a subsequent step, the pedal shaft 35 is inserted into the bottom bracket shell 3. 1, a non-positive connection is created between the central region 36 of the pedal shaft 35 and the connecting sleeve 5. The pedal shaft 35 can also be used later, in particular after the bottom bracket 3 is installed in the bottom bracket tube 7 of the bicycle frame 6.

FIG. 2 shows a schematic cross-sectional view of the bottom bracket according to the embodiment in FIG. 1 during the installation of the bottom bracket 1.

To install the bottom bracket 1 in the bicycle, the bottom bracket housing 3 is inserted from the left into the bottom bracket tube 7 of the bicycle frame 6, after which the left sleeve nut 2 is screwed into the bottom bracket tube 7 from the left side. As a result, the bottom bracket shell 3 is fixed on the left side on the bottom bracket tube 7. In a subsequent step, the right sleeve nut 4 is inserted into the bottom bracket tube from the right side (see the broad arrow in FIG. 2) and screwed in. So that the bottom bracket 3 is attached from both sides to the pedal tube 7. Fig. 3 shows a schematic cross-sectional view of a bottom bracket according to another exemplary embodiment. The embodiment of FIG. 3 essentially corresponds to the embodiment of FIG. 1. The same reference numbers are used for the same or equivalent parts. In contrast to the exemplary embodiment in FIG. 1, in the exemplary embodiment in FIG. 3 the left sleeve nut 2 and the right sleeve nut 4 are screwed to the bottom bracket shell 3 and not to the bottom bracket tube 7.

In the embodiment of FIG. 3, the outer wall 15 of the bottom bracket shell 3 has a left and a right external thread 22. In contrast to the embodiment of FIG. 1, the left sleeve nut 2 and the right sleeve nut 4 each have an internal thread de 23 instead of an external thread.

The bottom bracket 1 according to the embodiment of FIG. 2 can be installed in the bicycle essentially similar to the bottom bracket according to the embodiment of FIG. 1.

The already assembled and assembled bottom bracket housing 3 can be inserted from the left into the bottom bracket tube 7, after which the left sleeve nut 2 is screwed to the inside thread 23 on the left outside thread 22 of the bottom bracket housing 2. Alternatively, the left sleeve nut 2 can be screwed onto the bottom bracket 1 before the bottom bracket housing 3 is inserted into the bottom bracket tube 7. In a subsequent step, the right sleeve nut 4 is inserted from the right and screwed to the internal thread 23 on the right external thread 22 of the bottom bracket shell 2. This creates a positive connection between the bottom bracket tube 7 and the bottom bracket 1, so that the bottom bracket 1 can neither move to the right or to the left (with respect to the bottom bracket tube 7).

In operation, the bicycle is driven via pedals or pedal cranks, as a result of which the pedal shaft 35 is rotated with respect to the bicycle frame 6. The first encoder part 9, which is attached to the outer wall 15 of the bottom bracket shell 3, encircles the second encoder part 10, which is attached to the connecting sleeve 5, so that the magnet of the second encoder part 10 on the coil of the first Encoder part 9 passes again and again - essentially with every full revolution of the pedal shaft. Due to electromagnetic induction, the passing of the magnet induces an alternating voltage or alternating current on the coil in the coil, which can be passed via the electrical connection 13 to the evaluation and transmission circuit 1 1.

The four strain gauges 92 detect the deformation of the left bearing seat 90 due to mechanical stress and convert it into corresponding electrical signals. converts, which are passed on via the electrical connection 12 to the transmission and transmission circuit 11.

The evaluation and transmission circuit 11 can be designed in such a way that the signals received from the encoder 8 or from the first encoder part 9 and from the stretching strip 92 are evaluated in order to ascertain information about various operating parameters and via the antenna 14 to send a recipient, not shown here.

The evaluation and transmission circuit 11 can in particular be designed to determine the power introduced by the cyclist while cycling. In particular, the rotational speed of the pedal shaft 35 and the force exerted on the left bearing seat can be determined on the basis of the electrical signals supplied by the encoder 8 and by the strain gauge 92.

The evaluation and transmission circuit can also be designed to determine the current crank position of the bicycle. Based on the force at the current crank position and the speed of the pedal shaft 35, the power introduced by the cyclist can be determined.

The energy supply of the evaluation and transmission circuit 11 can be provided by the encoder 8, the current pulses or alternating current supplied by the encoder 8 being used both for the evaluation and for the energy supply of the evaluation and transmission circuit 11.

In some implementations, the evaluation and transmission circuit 11 has a rechargeable energy store, a battery, or a capacitor (not shown), the evaluation and transmission circuit being designed in such a way that the rechargeable energy store is charged by the current pulses supplied by the encoder 8 can.

In some embodiments, the bottom bracket 1 is designed to be watertight, the cutouts 16 being watertightly sealed with covers (not shown) which are permeable to transmission signals.

In some embodiments, the evaluation and transmission circuit 11 is designed to send and / or receive signals according to one of the protocols that can be used for wireless communication. In particular, the evaluation and transmission circuit 11 can send or receive signals in accordance with ANT + (protocol of the ANT alliance) in order, for example, to provide smooth connectivity with sports watches and bicycle computers. Furthermore, the evaluation and transmission circuit 11 can be designed to be Bluetooth Smart compatible in order to be able to work with applications on sports watches or smartphones.

The evaluation and transmission circuit 1 can in particular be designed to receive instructions via signals and, in particular, to be configured. For example, the evaluation and transmission circuit 11 can be instructed to send the power introduced by the cyclist to the receiver over certain time intervals at certain intervals or at certain time intervals.

FIG. 4 shows a perspective view of a bottom bracket or a load cell according to an embodiment, seen from the drive side. The bottom bracket 1 has four axial support brackets 101, on which an outer ring of a roller bearing 45, which leads out as a ball bearing, is supported in the axial direction, and four bearing seats 90 or measuring brackets arranged between the axial support brackets 101, on each of which a strain gauge 92 is applied is brought. For easier positioning of the strain gauges 92, the surfaces of the bearing seats 90 can be provided with depressions.

The axial support tabs 101 have an outer region 93 which rests on an outer ring of the ball bearing and an inner region 94. The region in which the outer ring of the ball bearing rests can be seen in the cross-sectional view of FIG. 1.

The measuring tabs 90 and the axial support tabs 101 are each laterally separated from one another by a milled radial slot 95. On the output side, the measuring tabs 90 merge into a receiving sleeve 96, which receives the outer ring of the ball bearing 45. This receiving sleeve 96 can best be seen in FIG. 9.

On the drive side, the tabs 90, 101 merge into an outer ring 97. The regions of the outer ring 97 that lie opposite the measuring tabs 90 and the radial slots 95 each have a circumferential slot 105 in the radial direction, which has approximately half the radial extent as the measuring tabs 90. A first radial slot 95, a circumferential slot 105 and a second radial slot 95 together form a limiting slot which runs in an angled U-shape and which separates the axial support tab 101 from the receiving sleeve 96 and from the adjacent measuring tabs.

The outer ring 97 has four fastening holes 98, with which the bottom bracket 1 can be fastened to a transmission housing, not shown in FIG. 1, one end face of the outer Rings 97 abuts the gear housing. Fastening of the bottom bracket 1 to the transmission housing is shown by way of example in FIGS. 15 and 16.

5 shows a view of the bottom bracket 1 with the ball bearing 45 arranged in the bottom bracket 1, seen from the drive side.

FIG. 6 shows a top view of the bottom bracket 1 with the roller bearing or ball bearing 45 arranged in the bottom bracket 1. As shown in FIG. 6, the measuring tabs 90 have areas 99 on the end face of the outer ring on the driven side , which are slightly set back from the output-side end face of the outer ring 97. As a result, the thickness of the measuring tabs can be reduced, so that there is greater deformation.

FIG. 7 shows a cross-sectional view of the bottom bracket 1 along the cross-sectional line A-A of FIG. 5, in which the recessed areas 99, the sleeve 96 and the outer ring 97 can be seen.

FIG. 8 shows a side view of the bottom bracket 1, in which slots 104 can be seen, which lie opposite the support straps 91, and through which the support straps 91 are separated from the sleeve 96.

9 shows a perspective view of the bottom bracket 1 seen from the driven side.

10 shows a view of the bottom bracket 1 seen from the driven side.

11 shows a cross-sectional view of the bottom bracket 1 along the section line A-A of FIG. 9.

FIG. 12 shows a cross-sectional view along the section line B-B of FIG. 26.

For the sake of simplicity, it is assumed below that the load cell is oriented in such a way that the measuring tabs are each arranged perpendicularly and horizontally to the road surface, that is to say parallel to the pedaling movement of the driver and perpendicularly thereto. However, other orientations are also possible.

The load cell described above can be used to determine a measurement of the force exerted on a pedal shaft. The load cell does not need any moving parts and takes up little space, especially in the axial direction, which makes better use of the available space. The space available for a bicycle is limited and the use of the load cell can be particularly advantageous there. In particular, the axial installation space is severely limited by the predetermined optimal distance of the pedal cranks.

During operation, a driver exerts forces on the pedals, particularly on the down pedal. As a result, a downward force acts on the pedal shaft on the side of the pedal pressed. In addition, a forward-facing force acts on the pedal shaft on the side of the pedal that has been depressed. Due to the lever arm on the bearing of the pedal shaft, an opposite force acts on the opposite side of the pedal shaft.

When pedaling, the left pedal and the right pedal are pressed alternately. Thus, with a constant cadence, a periodically alternating force occurs in the vertical direction and also in the horizontal direction. The amplitude of this force is correlated with the torque exerted on the pedal shaft. If the measuring straps are arranged vertically and horizontally, the vertical force on the pedal shaft is recorded by strain gauges of the vertically aligned pair of measuring clips and the horizontal force on the pedal shaft is recorded by strain gauges of the horizontally aligned pair of measuring clips.

The electrical signal of a strain gauge is approximately the same size and opposite to a signal of a radially opposite strain gauge. The measurement amplitude can thus be doubled with an arrangement of radially opposite strain gauges. This can be achieved by a subtractive overlay of the signals, which can be done by analog electronics or after digitizing the signal.

The signals of the strain gauges are forwarded via connecting lines to an electronic evaluation system, which is arranged on a circuit board, which is fastened to the transmission housing. According to a simple evaluation, an average torque is determined from one or more temporally adjacent maximum deflections of the signals of the strain gauges in accordance with a calibration curve, which is stored in a permanent memory of the evaluation electronics and generates an output signal therefrom, with the torque exerted on the pedal wave in is correlated in a simple manner, for example by proportional dependency.

According to a more complex evaluation, the further course of the signals over time is also included in the electronic evaluation and an output signal is generated therefrom by means of data previously stored in the memory, such as calibration curves and parameters. Furthermore, a current The angular position and / or rotational speed of the pedal shaft can be determined and included in the electronic evaluation.

The output signal can then be passed on to a further area of the evaluation electronics, which determines a required motor support of an electric motor of an electrically operated bicycle and generates a corresponding motor control signal. This engine control signal can in turn depend on other parameters, such as the angle of inclination of the vehicle, the current speed, a battery status or also on certain driving situations that are determined from these parameters, such as driving over a curb, starting from a standstill, or starting on an incline.

On the one hand, calibration can be carried out by directly calculating a calibration curve and other calibration parameters from the component properties and storing them in the memory. On the other hand, calibration can also be carried out by attaching a further sensor which measures the actual deformation of the pedal shaft and thus the torque exerted on the pedal shaft, while at the same time a periodic pedal force is applied to the pedals of the pedal shaft by a test device.

Calibration parameters are determined from the correlation of the applied pedaling force and the actual torque. These calibration parameters can then be stored in the evaluation electronics memory for all bicycles of the same model. It is also possible to store calibration parameters for different models in the same memory, with a further stored specification indicating the currently used model of the bicycle.

A measurement of the torque exerted on the pedal shaft can also be carried out for the purpose of calibration without a sensor attached directly to the pedal shaft by measuring the torque on the output shaft or on downstream gear elements.

FIGS. 13 and 14 illustrate a force conversion of a pedal force into a torque on a pedal shaft of a bicycle. Based on this type of force conversion on a pedal shaft, a torque exerted on the pedal shaft can be determined from bearing forces on the pedal shaft according to the present description, for example by a load cell according to the present description. A similar determination of a torque exerted on a crankshaft from the bearing forces on a crankshaft is also generally possible in the case of crankshafts, wherein it may have to be taken into account that several cranks and other components such as connecting rods can be involved in the power conversion. For this purpose it can be useful to measure at more than one point, i.e. to install more than one load cell.

As shown in FIGS. 13 and 14, a torque is generated on the pedal shaft by the lever arm of the pedal cranks when a driver exerts a vertically downward force F_P on the pedals.

In the sensor arrangement according to FIG. 5 of the description, a vertically aligned pair of strain gauges measures a vertical force component FJP of a radial force F R that is exerted on a bicycle crank. This vertical force component is also referred to as "pedal force" F_P. Furthermore, a second, vertically aligned pair of strain gauges measures a horizontal force component F H of the radial force F R.

The torque M exerted on the pedal shaft can then be calculated using the known length L of the pedal crank as follows. According to the lever law, the torque M on the pedal shaft is equal to the tangential force on the pedal crank multiplied by the lever arm R. In other words, M = F_T * R = F_P * sin (a) * R, where a is the pedal angle that is measured from top dead center.

The vertically directed force FJP is known from the measured values of the vertically arranged pair of strain gauges. The horizontal force F_H is also known from the measured values of the horizontally arranged pair of strain gauges. From the forces FJH and F_P, the radial force F_R can be determined according to the Pythagorean theorem according to FR - sqrt (F JP ^A 2 + F_h ^A 2), where sqrt denotes the square root function. The pedal angle a results from the ratio of the radial force to the vertical force according to a = arcos (FR / FP), and according to FR = sqrt (FJP ^A 2 + F_h ^A 2), as can best be seen in FIG. 14 is.

Taking into account the above-mentioned lever law M = FJP * sin (a) * R, the forces F_P and F_h determined by the strain gauges can therefore be used to determine the torque on this pedal shaft according to the following formula:

M = F_P * cos (arccos (sqrt (F_h ^A 2 + F_P ^A 2) / F_P)) This torque calculation, which uses only elementary relationships such as the lever law, the force parallelogram and the Pythagorean theorem, is general knowledge of the person skilled in the art and is only reproduced here for better understanding.

If the strain gauges or force sensors are not aligned horizontally and vertically, the torque can be determined by a similar calculation, especially if there are two pairs of opposing strain gauges. For the sake of simplicity, the horizontal-vertical arrangement is shown here.

In a further embodiment, not shown here, which largely corresponds to that of FIG. 3, the right bearing seat 91 also has four strain gauges 92 for detecting mechanical loads exerted on the right bearing seat 91, in particular perpendicularly with respect to the pedal shaft 35 . The four strain gauges 92 and the evaluation and transmission circuit 11 are connected to one another via additional electrical connections 12, not shown in FIG. 3.

The embodiment according to the above exemplary embodiment results in a particularly precise determination of the energy introduced by a rider of the bicycle. In this way, the forces of a chainring attached to the pedal shaft 35 can also be precisely taken into account when calculating the torque generated by the driver. Specifically, four Kraftvek factors attack the pedal shaft 35, which are converted into a torque via the correspondingly known lever arms of the pedal cranks or chainring, which in turn is converted into an input power using the rotational frequency.

To determine the cadence or rotational frequency, both data from the encoder 8 and the cyclic profile of the forces acting on the pedal shaft 35 can be used.

The evaluation and transmission unit 11 converts the AC voltage generated by the encoder 8 into DC voltage and stores it in an energy store (not shown here), a capacitor or a battery. The evaluation and transmission unit 11 uses this energy to operate and transmit the relevant signals with the measured values determined.

In a practical implementation of a torque measuring device, the above-mentioned dependence of the torque on an applied pedal force can also be determined only by calibration and stored in a computer-readable memory by means of one or more calibration tables. As a result, more complicated dependencies caused by unbalance, inertia and other effects can also be taken into account it is not necessary to know the length of the pedal crank or the exact orientation of the strain gauges in advance.

FIGS. 15 to 17 illustrate the absorption of radial and axial forces by two pedal shaft ball bearings, which are arranged in an X arrangement on the pedal shaft, and by a load cell or a pedal bearing 47. The direction of view of FIGS. 15 to 17 shows in Direction of travel.

15, the load cell 47 is fastened by screws which are subjected to tension. The load cell can also be attached to a gear housing on an opposite side. In this case, the axially outward forces are absorbed directly by the gear housing.

15 shows a gear arrangement with a load cell 47 according to a first embodiment, the load cell 47 being supported on a drive-side ball bearing 45 of an inclined bearing. The load cell 47 can be provided in particular by the load cell 1 from FIG. 4.

The inclined bearing has a pedal shaft 35 which has a larger diameter towards the center than at both ends, as a result of which a drive-side shoulder 106 and a drive-side shoulder 107 are formed. An inner ring of a drive-side ball bearing 45 is supported in the axial direction on the drive-side shoulder 106 and an inner ring of a drive-side ball bearing 46 is supported in the axial direction via a ring on the drive-side shoulder 107 of the pedal shaft 35.

This arrangement of the ball bearings 45, 46 supported inwards on the shaft is also referred to as an “X arrangement”. The ball bearings 45, 46 of the inclined mounting are designed as single-row angular contact ball bearings, the higher side of the respective inner ring pointing towards the center of the pedal shaft 35. A support tab of the load cell 47 shown in cross section is supported in the axial direction on the output side shoulder of the pedal shaft 35. A measuring lug 90 located behind it, to which a strain gauge 92 is attached, is supported in the radial direction on an outer ring of the drive-side ball bearing 45.

Furthermore, FIG. 15 shows a part of a motor housing 122, a part of a housing cover 132, an O-ring 142, and a cover nut 144 and pedal crank fastening areas 75. On a right side of the pedal shaft arrangement, an output from the pedal shaft can be made via a pedal shaft freewheel be led out to an output shaft, which is not the case in FIGS. 15-17 is shown. As an alternative to this, the output can also be guided to the left of the load cell 47 onto an output shaft.

FIGS. 16 and 17 show an arrangement similar to that in FIG. 15, in which a radial area of the measuring plates 90 and the supporting plates 91 lies in the same plane. For the sake of clarity, the sectional plane of FIG. 13 runs through a support bracket 91 and the sectional plane of FIG. 34 through a measuring bracket 90 of the load cell 47. As shown in FIG. 17, an axial one

Cross-section of the measuring tab 90 in the area of the strain gauge 92 is narrower than the axial cross-section of the support tab 91. A larger deformation in the area of the strain gauge 92 can be achieved in this way. The cross-section can be thinned, for example, by milling.

An improved method for motor control of an electric bicycle is described below. The method includes a sensor evaluation of sensor signals that originate from at least two opposite strain gauges that are attached to a part of an electric bicycle that absorbs the bearing forces of a pedal shaft. For example, strain gauges of the bottom bracket 1 of FIG. 1 or the strain gauges of the bottom bracket 1 or the load cell 1 of FIG. 4 can be used for this. This method can be combined with the exemplary embodiments from FIGS. 1-16. For example, the method can be carried out by the evaluation electronics 11.

The method can be used to achieve an improved compensation for a drift of an expansion element, which is caused, for example, by temperature or aging. In particular, an improved determination of a time period in which a driver does not deliver a pedal torque is provided, as a result of which an interruption phase is determined in which an electric motor does not provide motor support.

Furthermore, an improved control of an electric motor of the electric bicycle can be provided. For this purpose, an assist torque or an assist power of the electric motor is determined

A drive torque M total of the electric bicycle is composed of an engine torque, a chain torque and a pedal torque. Expressed as a formula, M_otal = M_motor + M chain + MJPedal. The instantaneous motor torque can be determined by an electrical power that is supplied to the motor and that can be determined, for example, from current and voltage. The sum of chain and pedal torque can be determined using a torque measuring device. Example This determination can be made by four strain gauges, taking advantage of the relationship shown in FIGS. 13 and 14.

In particular, a support torque M_U for a required motor support can be determined as a function of voltage values UJVtess of strain measuring elements, of an angle of rotation a of the pedal shaft and of a motor current I motor and possibly other values. Expressed as a formula, M_U == f (U_Mess, a, I_Motor).

17 shows a structure of a strain gauge (DMS) 108, a measurement direction being indicated by a double arrow. The strain gauge is an example of a strain gauge element. Other examples are magnetic and capacitive sensors. In general, it applies to strain gauges that a relative change in resistance is proportional to a relative change in length in the proportionality range. Expressed as a formula, the relationship AR / R = k * Dΐ / l applies. The constant k depends on the DMS used. Fig. 18 shows voltage characteristics for two different strain gauges with different slopes. Other effects such as prestressing in the material can also cause the zero points of two characteristic curves to also differ from one another. This is at least the case if no separate zero point calibration is carried out for the strain gauge.

The change in resistance can, for example, be converted into a change in voltage by one of the two Wheatstone bridges shown in FIGS. 20 and 21. Figures 20 and 21 show how the evaluation method can be used together with a Wheatestone measuring bridge. However, the evaluation method can also be carried out without such a measuring bridge.

In the pair or the two pairs of strain gauges, a strain gauge and a strain gauge can advantageously be loaded, which results in particular when a strain gauge is arranged opposite to the pedal shaft 35.

FIGS. 20 and 21 show an arrangement with two strain gauges 108, 109 and two resistors 112, 113 in a half bridge and an arrangement with four strain gauges 108, 109, 110, 111 in a full bridge. These arrangements can be used in particular in the exemplary embodiments of the preceding figures.

A voltage Uo is generated by a voltage source, which is connected to two connections 114, 115 of the Wheatstone bridge, and a measurement voltage UM, which is present between two measurement connections 1 16, 117 of the Wheatstone bridge, is provided with evaluation electronics connected the. According to an exemplary embodiment, the voltages applied to the two measuring connections 116, 117 can be determined separately. As a result, a voltage drop at the individual strain gauges 108, 109, 110, 111 can be measured and evaluated separately. For example, one pole of the voltage source can be connected to earth and used as a reference level, which means that it is sufficient to determine three of the four voltages which are present at the four terminals 114, 115, 116, 117 of the strain gauge and / or the resistors.

In the real measurement, the change in resistance due to the expansion is superimposed on an additional change in resistance as a disturbance variable, which is caused by temperature influences. The temperature influences the specific electrical resistance and also causes an additional change in length. Temperature compensation can be achieved, for example, by the half-bridge circuit shown in FIG. 20 or by the full-bridge circuit shown in FIG. 21.

Using Wheatstone bridges for temperature compensation works particularly well if the strains of all strain gauges are equal in amount. In the case of an arrangement around a pedal shaft bearing component, as is shown, for example, in FIG. 4, this is not always exactly fulfilled, among other things, due to slightly different distances from the pedal shaft or due to component tolerances.

Furthermore, the pedal shaft is not firmly connected to the component in which it is mounted. This is one of the reasons why the pulling force on the opposite side of the strain gage under pressure need not be equal to the pressure force exerted on the strain gage under pressure.

Another effect occurs through play in the camp. This effect is symbolized in the schematic drawing of FIG. 22, in which a central element 117 symbolizes the pedal shaft 35 and upper and lower elements 118, 119 connected to spring elements each represent the strain measuring sensors. Due to the play in the bearing, the pedal shaft lifts off the first strain sensor before it comes into contact with the second strain sensor and vice versa. 23 shows this effect in a simplified manner on a pedal shaft 35 which is mounted in a cylindrical receiving area. For the sake of simplicity, other elements of the bearing, such as rolling elements, inner ring, outer ring and bearing cage, which also contribute to the bearing play, have been omitted.

24 shows a first pair of force-displacement characteristics 120, 121 for a pedal shaft arrangement with two strain gauges, in which there is little or no bearing play. In this case At least one of the two strain gauges always absorbs pressure, regardless of the position of the pedal shaft. A change between a compressive force on the first strain gauge and a compressive force on the second strain gauge takes place at a reference value 123 of a path s and a reference value 124 of a force F.

25 shows a second pair of force-displacement curves 120 ', 121' for a pedal shaft arrangement with two strain gauges in which there is a bearing play, so that neither of the two strain gauges has a force F over a play area 125 of the position s of the pedal shaft records.

A change between a pressure force on the first strain gauge to the play area takes place at a path 126 and a force 127 and a change from the play area to a pressure force on the second strain gauge takes place at a reference value 128 of the stroke s and a reference value 127 the force F.

Further features of the subject matter of the present description, which can be combined with one another and with the other features of the description, appear from the following list.

1. a bottom bracket for a bicycle, comprising:

a left sleeve nut (2),

a bottom bracket shell (3),

a right sleeve nut (4),

wherein the bottom bracket housing (3) has a left bearing seat (90) with a left roller bearing (45) and a right bearing seat (91) with a right roller bearing (46), the left bearing seat (90) and / or the right bearing seat (91 ) has at least one deformation sensor (92), an inner ring of the left roller bearing (45) and / or an inner ring of the right roller bearing (46) having at least one position sensor (8), which is the one or the latter Determined position with respect to the bottom bracket housing (3), and further comprising an evaluation and transmission circuit (11) for harvesting the electrical signals supplied by the deformation sensor (92) and / or the position sensor (8) and for transmitting the signals evaluated by the Data obtained, the evaluation and transmission circuit (11) evaluating and storing an energy store for storing electrical energy supplied by the position sensor (8) for the operation of the deformation sensors (92) and / or Has transmission circuit (11). 2. Bottom bracket according to bullet point 1, a connection sleeve (5) for receiving a pedal shaft (35) being provided between the inner ring of the left roller bearing (45) and the one inner ring of the right roller bearing (46), the position sensor (8) in the area between the connecting sleeve (5) and the bottom bracket shell (3) is arranged.

3. bottom bracket according to one of the preceding bullet points, wherein the energy storage has a capacitor and / or a rechargeable battery, and wherein the evaluation and transmission circuit (1 1) is designed so that the energy storage by the at least one sensor (8 ) electrical signals supplied can be charged. (Rectifier)

4. bottom bracket according to one of the preceding bullet points, wherein the deformation sensor has at least one strain gauge (92).

5. bottom bracket according to bullet 4, wherein the left bearing seat (90) and / or right La gersitz (91) at least one perpendicular to the axis of rotation of the left roller bearing (45) and the right roller bearing (46) directed flat area, and wherein Strain gauge (92) is arranged on the flat area.

6. bottom bracket according to bullet point 4 or 5, wherein several strain gauges (92) are seen before, which are evenly distributed around the circumference of the right bearing seat.

7. Bottom bracket according to one of the preceding bullet points, the position sensor as an encoder (8) with a first encoder part (9) fastened on the inside of the bottom bracket housing (3) and with a second encoder part arranged opposite the first encoder part (9) (10) is formed, and wherein the second encoder part (10) comprises a (permanent) magnet and the first encoder part (9) comprises a coil for detecting electromagnetic fields generated by the magnet.

8. bottom bracket according to one of the preceding bullet points, wherein the bottom bracket housing (3) for electromagnetic signals transmissive transmission holes (16).

9. bottom bracket according to bullet point 8, the transmission holes (16) being watertight with covers that are permeable to electromagnetic signals. 10. bottom bracket according to one of the preceding bullet points, the left sleeve nut (2) and the right sleeve nut (4) each having an external thread (20) for screwing into corresponding internal thread (21) of a frame tube (7) of a bicycle frame (6) are provided.

11. bottom bracket according to one of the preceding bullet points, the left sleeve nut (2) and the right sleeve nut (4) are each provided with an internal thread for screwing onto corresponding external threads of the bottom bracket housing (3). 12. Bottom bracket according to one of the preceding bullet points, the evaluation and transmission circuit (11) being designed to wirelessly transmit and / or receive signals according to a protocol that can be used for wireless communication.

13. Bottom bracket according to one of the preceding bullet points, the evaluation and transmission circuit (11) being designed, based on the signals supplied by the at least one deformation sensor (92) to the evaluation and transmission circuit (11), introduced into the bottom bracket (1) To determine performance.

14. Bottom bracket according to one of the preceding bullet points, the evaluation and transmission circuit (11) being designed to determine the power introduced by the cyclist on the basis of a previously determined correlation between the input power and the signals supplied by the deformation sensor (92).

15. Bicycle, comprising a bicycle frame (6) with a bottom bracket tube (7), a bottom bracket (1) according to one of the preceding bullet points being mounted in the bottom bracket tube (7).

Reference numbers

1 bottom bracket 91 right bearing seat

2 left sleeve nuts 92 strain gauges

3 bottom bracket shell 93 outer area

4 right sleeve nut 94 inner area

5 connecting sleeve 95 radial slot

6 bicycle frame 96 sleeve

7 Bottom bracket tube 97 outer ring

8 encoders 98 mounting holes

9 first encoder part 99 reset area

10 second encoder part 101 axial support bracket

11 Evaluation and transmission unit 104 slot

12 electrical connection 105 circumferential slot

13 electrical connection 106 drive-side shoulder

14 Antenna 107, output-side shoulder

15 outer wall 108 strain gauges

16 recesses 109, 110, 111, 112 strain gauges

20 external thread of the sleeve nut 1 12, 1 13 resistance

21 internal thread of the frame tube 113, 114, 115, 116 connection

22 external thread of the bottom bracket shell 1 17 element

ses 118, 1 19 element

23 internal thread of the sleeve nut 120, 121 force-travel characteristic

25 weld 122 motor housing

35 pedal shaft 123 way

36 inner area of the pedal shaft 124 force

37 End area of the pedal shaft 125 Game area

45 left roller bearing 126 way

46 right rolling bearing 127 force

47 Load cell 128 way

75 attachment areas 129 force

90 left bearing seat 132 housing cover

142 O-ring 142

144 cover nut

Claims

Expectations

1. A device for determining a motor support of an electric motor for supporting a pedal torque provided by a driver of the electric bicycle, comprising:

a pedal shaft receiving area, the pedal shaft receiving area having a first strain measuring element in a first area of the pedal shaft receiving area and a second strain measuring element in a second area of the pedal shaft receiving area, the second area having the first area with respect to the bottom bracket

Opposite exposure area,

evaluation electronics which are connected to the first strain measuring element and to the second strain measuring element and which are set up to

receive a first signal from the first strain gauge and a second signal from the second strain gauge,

determine a first reference value of the first signal

determine a second reference value of the second signal

and disable motor assistance based on the first reference value and the second reference value.

2. Device according to claim 1,

the evaluation electronics being set up to

deactivate the motor support if the signal of the first strain measuring element is essentially constant and the signal of the second strain measuring element is essentially constant, and activate the motor support if the signal of the second strain measuring element has a predefined range by the value that it left when the motor support was deactivated, or when the signal of the first strain measuring element left a predefined range by the value that it assumed at the start of the deactivation period.

3. Device according to claim 1,

the evaluation electronics being set up to deactivate the motor support when the signal of the first strain measuring element reaches the first reference value and the signal of the second strain measuring element reaches the second reference value, and to activate the motor support when the signal of the second strain measuring element

Element leaves the second reference value or when the signal of the first strain gauge element leaves the first reference value.

4. Device according to one of the preceding claims,

wherein the evaluation electronics is set up to determine the first reference value and the second reference value in each case, in which the evaluation electronics checks whether a signal of the first strain measuring element is essentially constant in sections within a predefined measuring range during a driving cycle and at the same time a signal of the second strain gauge element is substantially constant, and, if so, to store the constant value of the first signal as the first reference value and the constant value of the second signal as the second reference value.

5. The device according to claim 1, wherein the pedal shaft receiving area further comprises a third strain measuring element in a third area of the pedal shaft receiving area and a fourth strain measuring element in a fourth area of the pedal shaft receiving area.

the fourth area being opposite to the third area with respect to the pedal wave receiving area,

and wherein the evaluation electronics is also set up to

receive a third signal from the third strain gauge and a fourth signal from the fourth strain gauge,

determine a third reference value of the third signal

determine a fourth reference value of the fourth signal, and

deactivate motor assistance based on the first reference value, the second reference value, the third reference value and the fourth reference value.

6. The device according to claim 5,

the evaluation electronics being set up to

deactivate the motor support if the signal of the third strain gauge element is essentially constant,

and the signal of the fourth strain gauge is substantially constant and to activate the motor support if the signal of the third strain gauge leaves a predefined range around the value which it assumed when the motor support was deactivated, or if the signal of the fourth strain measuring element leaves a predefined range around the value which it assumed at the beginning of the deactivation period.

7. The device according to claim 5, wherein the evaluation electronics are configured to deactivate the motor support when the signal of the third strain measuring element reaches the third reference value and the signal of the fourth strain measuring element reaches the fourth reference value, and to activate the motor support when the signal of the third strain measuring element Element leaves the third reference value or if the signal of the fourth strain gauge

Elements leaves the fourth reference value.

8. Device according to one of claims 5 to 7,

wherein the evaluation electronics is set up to determine the third reference value and the fourth reference value in each case, in which the evaluation electronics checks whether a signal of the third strain measuring element is essentially constant in sections within a predefined measuring range and a signal of the fourth strain gauge element is substantially constant in sections, and, if this is the case, to store the constant value of the third signal as the third reference value and the constant value of the fourth signal as the fourth reference value.

9. Device according to one of claims 5 to 8, wherein the evaluation electronics is further configured to determine a sum of a pedal torque and a chain torque from the first signal, the second signal, the third signal and the device, and wherein the device furthermore has an angle sensor for determining a pedal shaft angle and a current sensor for determining a motor current supplied to the electric motor, and wherein the evaluation electronics is further configured for the sum of the pedal torque and the chain torque, the pedal shaft angle, and the motor current Determine support power and control the electric motor to provide the support power.

10. The device according to one of claims 1 to 8,

still showing:

a torque sensor for determining a sum of pedal torque and

Chain torque,

an angle sensor for determining a pedal shaft angle and a current sensor for determining a motor current supplied to the electric motor, and wherein the evaluation electronics are further configured to determine a support power from the sum of the pedal torque and the chain torque, the pedal shaft angle, and the motor current and to control the electric motor to provide the support power.

11. Electric bicycle with a device according to one of claims 1 to 10, comprising: control electronics of the electric motor, which is set up to communicate with the device, the electric motor, which is connected to the control electronics, and with an driven wheel of the electric bicycle, a pedal shaft that is supported in the pedal shaft receiving area.

12. Method for determining a motor support of an electric motor of an electric bicycle in order to support a pedal torque provided by a driver of the electric bicycle, the electric bicycle being a bottom bracket with a pedal shaft

Receiving area, wherein the pedal shaft receiving area has a first strain measuring element in a first area of the pedal shaft receiving area and a second strain measuring element in a second area of the pedal shaft receiving area, the second area opposite the first area with respect to the bottom bracket receiving area , and

the method comprising:

Receiving a first signal from the first strain gauge and a second signal from the second strain gauge,

Determining a first reference value of the first signal,

Determining a second reference value of the second signal, and

Disable motor assistance based on the first reference value and the second reference value.

13. The method of claim 12, further comprising:

Deactivate the motor support if the signal of the first strain gauge in the

Is essentially constant

and the signal of the second strain gauge element is substantially constant, and activating the motor support if the signal of the second strain gauge element leaves a predefined range around the value which it assumed when the motor support was deactivated, or if the signal of the first strain measuring element leaves a predefined range around the value which it assumed at the beginning of the deactivation period.

14. The method of claim 12, further comprising:

Deactivating the motor support when the signal of the first strain gauge reaches the first reference value and the signal of the second strain gauge reaches the second reference value Activating motor support when the signal of the second strain gauge leaves the second reference value or when the signal of the first strain gauge leaves the first reference value.

15. The method according to any one of claims 12 to 14, further comprising:

Determining the first reference value and the second reference value, the determination of the first reference value and the second reference value comprising the following steps:

Check whether a signal of the first strain-measuring element is essentially constant in sections and at the same time a signal of the second strain-measuring element is substantially constant in sections within a predefined measuring range, and, if this is the case,

Storing the constant value of the first signal as the first reference value, and

Store the constant value of the second signal as a second reference value.

16. The method according to any one of claims 12 to 15, wherein the pedal shaft receiving area further comprises a third strain measuring element in a third area of the pedal shaft receiving area and a fourth strain measuring element in a fourth area of the pedal shaft receiving area.

and the method further comprises:

Receiving a third signal from the third strain gauge and a fourth signal from the fourth strain gauge,

Determining a third reference value of the third signal,

Determining a fourth reference value of the fourth signal, and

Disabling motor assistance based on the first reference value, the second reference value, the third reference value and the fourth reference value.

17. The method of claim 16, further comprising:

Deactivating the motor support if the signal of the third strain gauge element is essentially constant,

and the signal of the fourth strain gauge is substantially constant, and activating the motor support when the signal of the third strain gauge leaves a predefined range by the value which it assumed when the motor support was deactivated, or when the signal of the fourth strain gauge element leaves a predefined range around the value that it assumed at the beginning of the deactivation period.

18. The method of claim 16, further comprising:

Deactivating the motor support when the signal of the third strain gauge reaches the third reference value and the signal of the fourth strain gauge reaches the fourth reference value

Activation of motor support when the signal of the third strain gauge leaves the third reference value or when the signal of the fourth strain gauge leaves the fourth reference value.

19. The method according to any one of claims 16 to 18, further comprising:

Determining the third reference value and the fourth reference value, the determination of the third reference value and the fourth reference value comprising the following steps: checking whether a signal of the third strain measuring element is essentially constant in sections within a predefined measuring range and a signal at the same time of the fourth strain measuring element is essentially constant in sections, and, if this is the case,

Storing the constant value of the third signal as the first reference value and storing the constant value of the fourth signal as the fourth reference value.

20. The method according to any one of claims 16 to 19, wherein the electric bicycle further comprises an angle sensor for determining a pedal shaft angle and a current sensor for determining a motor current supplied to the electric motor, and wherein the method further comprises:

Determining a sum of a pedal torque and a chain torque from the first signal, the second signal, the third signal and the fourth signal, determining an assist power from the sum of the pedal torque and the chain torque, the pedal shaft angle, and the motor current, and driving the Electric motor to provide the support power.

21. The method according to any one of claims 12 to 20, wherein the electric bicycle

has a torque sensor for determining a sum of pedal torque and chain torque, and an angle sensor for determining a pedal shaft angle and a current sensor for determining a motor current supplied to the electric motor, and the method further comprises Determining a support power from the sum of the pedal torque and the chain torque, the pedal shaft angle, and the motor current, a support power, and driving the electric motor to provide the support power.