Arrangement for detecting a rotational movement of a pedal shaft of a bicycle

Abstract

The invention relates to an arrangement for detecting a rotational movement of a pedal shaft of a bicycle, comprising a housing element, the pedal shaft, which is arranged to be rotatable relative to the housing element, a magnetic field sensor, which is arranged on the housing element, and a modulation element, which is arranged to be rotatable together with the pedal shaft, wherein the modulation element is designed to modulate a magnetic field differently with respect to the circumference of the pedal shaft, and an evaluation unit, which is set up to determine a rotational movement of the pedal shaft based on a sensor signal of the magnetic field sensor.

Description

State of the art

[0001] The present invention relates to an arrangement for detecting a rotational movement of a pedal shaft of a bicycle, and to a bicycle.

[0002] Arrangements for bicycles, particularly electric bicycles, are known that are configured to detect rotational movements of a pedal shaft of the bicycle. Detection of the rotational movement may be necessary, for example, to adapt the control of a drive unit that can generate a motor torque to assist the pedaling power of a bicycle rider. Various arrangements are known for detecting the rotational movement, which typically include their own sensor technology, such as separate rotary encoders or the like. Disclosure of the invention

[0003] The arrangement according to the invention with the features of claim 1 is distinguished in that a rotational movement of a pedal shaft of a bicycle can be precisely determined in a particularly simple and cost-effective manner. For example, a particularly simple sensor system can be used for this purpose. In particular, an already existing sensor system can be modified in a particularly simple manner. This is achieved according to the invention by an arrangement for detecting a rotational movement of a pedal shaft of a bicycle, preferably an electric bicycle, comprising a housing element and the pedal shaft, which is arranged so as to be rotatable relative to the housing element, for example by means of a bottom bracket. In addition, the arrangement comprises a magnetic field sensor, which is arranged on the housing element, and a modulation element, which is arranged so as to be rotatable together with the pedal shaft.The modulation element is designed to modulate a magnetic field differently with respect to the circumference of the treadmill, particularly during rotation of the treadmill shaft. Furthermore, the arrangement comprises an evaluation unit configured to determine the rotational movement of the treadmill shaft based on a sensor signal from the magnetic field sensor. The magnetic field sensor is preferably configured to detect a magnetic field strength.

[0004] In other words, an arrangement is provided which has a magnetic field sensor arranged in a stationary manner on the housing element. The arrangement also has a modulation element which is arranged together with the treadmill shaft and is therefore rotatable relative to the magnetic field sensor. The modulation element causes a modulation of the magnetic field during the rotation of the treadmill shaft, in particular in the area of the magnetic field sensor. The magnetic field sensor detects the magnetic field strength and generates a corresponding sensor signal, which is evaluated by the evaluation unit. Based on this sensor signal, the evaluation unit determines the current rotational movement of the treadmill shaft. For example, a temporal signal curve and / or a signal strength of the sensor signal of the magnetic field sensor can be analyzed by the evaluation unit in order to determine the rotational movement.

[0005] The arrangement thus offers the advantage of being able to determine the current rotational movement of the pedal shaft using a particularly simple, cost-effective, and space-saving design. By sensing based on the magnetic field detected by the magnetic field sensor, a particularly simple design is possible, requiring minimal additional space and allowing precise and robust detection against environmental influences.

[0006] The subclaims contain preferred developments of the invention.

[0007] Preferably, the evaluation unit is configured to determine a rotational speed of the pedal shaft based on the sensor signal of the magnetic field sensor. In particular, the determined rotational speed corresponds to a pedal frequency, i.e., a cadence, a rotational movement of a bicycle rider. For example, the rotational speed can be determined based on an analysis of a temporal signal profile of the sensor signal. This allows the rotational speed of the pedal shaft to be determined particularly easily and without, for example, the need for an additional cadence sensor.

[0008] Preferably, the evaluation unit is configured to determine a current angular position of the pedal shaft based on the sensor signal of the magnetic field sensor. The angular position can be considered, in particular, to be a current position of the pedal shaft with respect to a rotation about a pedal axis of the pedal shaft, preferably with respect to a predefined zero position. For example, a current angular position and thus a current position of cranks of a crank drive of the bicycle, in particular cranks fixed in a rotationally fixed manner to the pedal shaft, can be determined based thereon. For example, the angular position can be determined based on the magnitude of a current value of the sensor signal of the magnetic field sensor. The current position of the pedal shaft can thus be determined using a particularly simple structure.

[0009] Particularly preferably, the magnetic field sensor is configured for three-axis detection of a magnetic field strength. This means that, in particular, the magnetic field sensor is configured to detect a magnetic field strength along three independent spatial directions. Preferably, the three axes are arranged orthogonally to one another. This allows for particularly clear and precise detection. Furthermore, the rotational movement of the pedal shaft is determined based on the detected magnetic field strength along a single spatial direction, preferably parallel to the pedal axis along which the pedal shaft extends.

[0010] Further preferably, the modulation element is formed at least partially from a ferromagnetic material. The modulation element can preferably be formed from a soft magnetic material for magnetic cores. Particularly preferably, the modulation element is designed as a transformer sheet. This enables the detection of the rotational movement using a particularly simple and cost-effective construction. For example, by appropriately designing the geometry of the modulation element itself, the modulation of the magnetic field along the circumference can be easily enabled.

[0011] More preferably, the modulation element is designed as a sheet metal disc. In particular, the modulation element extends in a sheet metal plane, which is preferably orthogonal to the pedal axis of the pedal shaft. This enables a particularly simple and cost-effective construction.

[0012] The modulation element preferably has a plurality of radially protruding regions distributed around the circumference, preferably evenly. The regions can preferably be designed to protrude radially outwards, in particular from an annular base region. For example, the modulation element can be star-shaped, in particular with a plurality of tips or prongs protruding from the base region. Alternatively, the modulation element can preferably be cross-shaped, in particular with a plurality of radially protruding rectangular elements. Further alternatively, the modulation element can preferably have an oval outer circumference. Further alternatively, further geometries of the modulation element which are asymmetrical along the circumferential direction can be provided, which bring about different modulations of the magnetic field upon rotation of the modulation element.Preferably, different numbers of protruding regions can be provided, preferably at least 2, more preferably a maximum of 20. Another alternative embodiment of the modulation element is possible in the form of a ring formed as a corrugated sheet. This allows for a flexible geometry of the modulation element that is easy to manufacture and reliably effects the modulation of the magnetic field in such a way that it can be detected by the magnetic field sensor in order to determine the rotational movement of the treadmill.

[0013] Further preferably, the modulation element is fixed to the pedal shaft. Alternatively or additionally, the modulation element is preferably fixed to an inner ring of a bottom bracket, which can preferably be part of the assembly and is configured to rotatably support the pedal shaft relative to the housing element. For example, the modulation element can be fixed to the pedal shaft and / or the inner ring by means of a welded connection. This enables particularly simple and cost-effective production of the assembly.

[0014] Preferably, the modulation element is attached to a crank that is rotationally fixed to the pedal shaft. For example, in this case, the modulation element can be designed as a permanent magnet. Preferably, this allows a rotational movement of the crank to be directly detected.

[0015] The arrangement preferably further comprises a bottom bracket and a spring arrangement. The spring arrangement is designed to allow a radial movement of the pedal shaft relative to the housing element against a spring force. The pedal shaft is rotatably mounted relative to the housing element by means of the bottom bracket. The detection unit is further designed to detect the relative radial movement of the pedal shaft to the housing element based on the sensor signal of the magnetic field sensor and to determine a bearing force on the bottom bracket based on the detected relative radial movement. In other words, a certain movement of the pedal shaft relative to the housing element in the radial direction of the pedal shaft is permitted by means of the spring arrangement. This relative radial movement of the pedal shaft to the housing element is detected by means of the magnetic field sensor and the detection unit.The bearing force at the bottom bracket is preferably determined based on the detected relative movement and preferably additionally based on previously known geometric and / or mechanical properties of the components of the arrangement, such as a spring constant of the spring arrangement. This allows both the bearing force and the rotational movement of the pedal spindle to be determined simultaneously using a particularly simple, cost-effective and space-saving design. The bearing force is preferably detected based on magnetic field strengths detected by the three-axis magnetic field sensor along two directions orthogonal to the pedal axis. This allows for particularly precise and reliable detection of the bearing force. The relative radial movement is preferably detected directly as a distance or length.As a result, the bearing force can be determined particularly easily and precisely, for example when the mechanical properties of the spring arrangement are already known. The spring element is preferably designed as an isotropically acting spring. This allows the relationship between the detected relative radial movement and the bearing force to be determined particularly easily and precisely. The spring element is preferably designed as an elastomer spring, and / or as a corrugated sheet spring, in particular made of metal, and / or as a cardanically acting cylindrical spring, in particular made of metal, and / or as a plurality of preferably elastic keys distributed around the circumference. In particular, the isotropic effect of the spring element, in particular in accordance with Hooke's law, brings about a proportional increase in the restoring spring force with increasing deflection.This allows, particularly with a suitable design of the spring element, the maximum relative radial movement can be limited by design under typically occurring forces. This can provide particularly high user comfort for the bicycle rider, as minimal movement in the arrangement can be enabled, which, for example, is imperceptible to the rider.

[0016] Alternatively, the spring element is preferably designed as an anisotropic spring, particularly preferably as a multi-component polymer spring. This alternative design allows for a simple and cost-effective way to provide the special flexible bearing of the pedal shaft relative to the bearing shell, with the precise possibility of determining the bearing force.

[0017] Furthermore, the invention leads to a bicycle, preferably an electric bicycle, which comprises the described arrangement. The bicycle preferably comprises a crank drive, which has cranks, the pedal shaft, and two bottom brackets for supporting the pedal shaft. In addition, the bicycle preferably comprises a chainring, which is connected to the pedal shaft, and a drive unit, which is configured to provide a motor torque to assist a rider torque generated by a rider, in particular by means of muscle power. The pedal shaft is mounted within the drive unit by means of the two bottom brackets. The arrangement described above is configured to detect the rotational movement and / or bearing force on at least one of the two bottom brackets.The bearing force determination by means of the arrangement has the advantage that the pedal shaft can be designed in a particularly simple and cost-effective manner, whereby a reliable determination of the forces used to actuate the drive unit is possible. Short description of the drawings

[0018] The invention is described below using exemplary embodiments in conjunction with the figures. In the figures, functionally identical components are identified by the same reference numerals. Here: Fig. 1 is a simplified schematic view of an electric bicycle with an arrangement according to a first embodiment of the invention, Fig. 2 a simplified schematic detailed view of the arrangement of the Fig. 1, Fig. 3 a simplified schematic detailed sectional view of the arrangement of the Fig. 1, Fig. 4 a further simplified schematic detailed view of the arrangement of the Fig. 1, Fig. 5 to 10 simplified schematic detail views of various embodiments of modulation elements of the arrangement of the Fig. 1, and Fig. 11 a simplified schematic detailed view of an arrangement according to a second embodiment of the invention. Preferred embodiments of the invention

[0019] Fig. 1 shows a simplified schematic view of an electric bicycle 100 with an arrangement 1 for detecting a rotational movement of a pedal shaft 4 of the electric bicycle 100 according to a first embodiment of the invention.

[0020] Details of arrangement 1 are shown in simplified schematic detail views in the Fig. 2 to 4.

[0021] The electric bicycle 100 has a crank drive with two cranks 104 located opposite one another with respect to a pedal axis 30. Pedals are arranged on the cranks 104, via which a rider can generate a rider torque using muscle power.

[0022] In addition, the crank drive comprises a pedal shaft 4, which is connected in a rotationally fixed manner to the cranks 104, and two bottom brackets 10 for the rotatable mounting of the pedal shaft 4.

[0023] The electric bicycle 100 further comprises a chainring 107, which is connected in a rotationally fixed manner to the pedal shaft 4, and a bicycle chain, which is in engagement with the chainring 107.

[0024] To support the rider torque with an additional motor torque, the electric bicycle 100 comprises a drive unit 106 which is configured to generate the motor torque, preferably by means of an electric motor which is supplied with electrical energy in particular by an electrical energy storage device 109.

[0025] The pedal shaft 4 is preferably rotatably mounted in the drive unit 106 by means of the two bottom brackets 10.

[0026] The bottom bracket 10 is designed as a rolling bearing and comprises an inner ring 11 and an outer ring 12 and a plurality of rolling elements 19 arranged between the inner ring 11 and the outer ring 12.

[0027] During motor-assisted operation of the electric bicycle 100, the motor torque is adjusted depending on the rider torque applied by the rider. The rider torque is determined by determining a bearing force on at least one bottom bracket 10, preferably on the chainring-side bottom bracket, using the arrangement 1, as described later.

[0028] In addition, a rotational movement of the treadmill shaft 4 can be detected and monitored by means of the arrangement 1.

[0029] The arrangement 1 comprises a magnetic field sensor 31, by means of which sensor data is generated, based on which both the bearing force and the rotational movement of the pedal shaft 4 can be detected simultaneously.

[0030] The magnetic field sensor 31 is designed as a three-axis sensor and is configured to measure magnetic field strengths along mutually orthogonal axes 35a, 35b, 35c (cf. Fig. 3 and Fig. 4). The first two axes 35a, 35b lie in a plane orthogonal to the pedal axis 30. The third axis 35c is arranged parallel to the pedal axis 30.

[0031] The magnetic field sensor 31 is fixedly arranged on a housing element 5 of the drive unit 106. In particular, the housing element 5 can also be considered a bearing shell in which the bottom bracket 10 is held.

[0032] The arrangement 1 further comprises an evaluation unit 3, which is connected to the magnetic field sensor 31 and which is configured to evaluate the sensor signal of the magnetic field sensor 31 and to determine the bearing force and the rotational movement of the pedal shaft 4 based on the detected sensor signal.

[0033] To detect the rotational movement, the arrangement 1 further comprises a modulation element 32, which is arranged to rotate together with the pedal shaft 4. The modulation element 32 is fixed to the inner ring 11 of the bottom bracket 10 (see Fig. 3 and Fig. 4).

[0034] The modulation element 32 is designed as a sheet metal disc made of a ferromagnetic material, in particular as a transformer sheet. The modulation element 32 has a plurality of radially outwardly projecting regions 32a distributed around the circumference, which project in particular in the radial direction up to the level of the magnetic field sensor 31 (cf. in particular Fig. 4).

[0035] The Fig. 5 to 10 show different preferred embodiments of the modulation element 32. The modulation elements 32 of the Fig. 5 to 10 differ only in the geometry and number of radially projecting areas 32a.

[0036] Fig. 5 shows a cross-shaped geometry with a total of four protruding areas 32a, particularly designed as rectangular tabs.

[0037] The Fig. 6 and Fig. 7 show star-shaped modulation elements 32 with protruding areas 32a formed as spikes or triangles. In Fig. 6 there are a total of seven protruding areas 32a, and in Fig. 7 a total of 24 radially projecting areas 32a are provided.

[0038] Fig. 8 shows a modulation element 32 with a total of four radially projecting regions 32a, which are essentially trapezoidal in shape.

[0039] Fig. 9 shows a modulation element 32 which has an oval outer geometry, by which a total of two protruding regions 32a are formed.

[0040] Fig. 10 shows a modulation element 32 which is designed in the form of a corrugated ring.

[0041] During the rotation of the treadmill shaft 4 relative to the housing element 5, the modulation element 32, through its material and geometry, causes an alternating modulation of the magnetic field in the area of the magnetic field sensor 31 corresponding to the rotational movement. Based on the magnetic field strength detected by the magnetic field sensor 31, in particular along the third axis 35c, the evaluation unit 3 can then determine the current rotational movement of the treadmill shaft 4. In particular, the rotational speed and the current angular position of the treadmill shaft 4 relative to the housing element 5 are determined.

[0042] In addition, the arrangement 1 comprises a spring arrangement 2, by means of which the bearing force 50 can be determined (cf. Fig. 2). The spring assembly 2 has a spring element 21, which is designed as a leaf spring, for example made of metal, that is convexly curved toward the pedal axis 30. The spring element 21 is arranged in a recess of the housing element 5 and exerts a spring force 20 on the outer ring 12 of the bottom bracket 10.

[0043] The spring assembly 2 allows a certain degree of flexibility through the resilient spring element 21, thus allowing a relative radial movement of the pedal shaft 4 to the bottom bracket 10 and the housing element 5 when a force is applied to the pedal shaft 4 in the radial direction. In particular, this force can be regarded as essentially corresponding to a resulting bearing force 50. The spring assembly 2 thereby causes the spring force 20 to act opposite to the bearing force 50.

[0044] The evaluation unit 3 is configured to detect the relative radial position change of the treadmill shaft 4 relative to the housing element 5 based on the sensor data of the magnetic field sensor 31. For this purpose, the magnetic field strength detected by the magnetic field sensor 31 is evaluated along the first two axes 35a and 35b. For improved detection, a permanent magnet 31a can be arranged on the outer ring 12.

[0045] Based on the detected relative radial movement of the pedal shaft 4 and based on the previously known mechanical properties of the spring arrangement 2, the evaluation unit 3 calculates the resulting bearing force 50 at the bottom bracket 10.

[0046] The arrangement 1 offers the advantage of a particularly simple, cost-effective, and compact design for detecting the bearing force 50 and, at the same time, for detecting the rotational movement of the treadmill shaft 4. In particular, a flexible arrangement of the components is enabled while requiring a particularly small amount of space. The simple detection technique using the magnetic field sensor 31 also allows for particularly insensitive detection, which is, for example, insensitive to external magnetic fields or the like.

[0047] Fig. 11 shows a simplified schematic detailed view of an arrangement 1 according to a second embodiment of the invention. The second embodiment essentially corresponds to the first embodiment of the invention, with the difference that a permanent magnet 31b is additionally arranged on the chainring-side crank 104. This allows for additional rotational movement-dependent modulation of the magnetic field, which can be detected by the magnetic field sensor 31. For example, the current angular position of the crank 104 can be determined directly and particularly reliably and precisely.

[0048] In the second embodiment of the Fig.11, for example, the modulation element 32 fixed to the inner ring 11 and additionally the permanent magnet 31b are provided. In an alternative preferred embodiment, the permanent magnet 31b can also be provided alone. For example, in this case, the permanent magnet 31b on the crank 104 can form the modulation element 32 of the arrangement 1.

Claims

[1] Arrangement for detecting a rotational movement of a pedal shaft (4) of a bicycle (100), comprising: - a housing element (5), - the pedal shaft (4), which is arranged to be rotatable relative to the housing element (5), - a magnetic field sensor (31) arranged on the housing element (5), and - a modulation element (32) which is arranged to be rotatable together with the treadle shaft (4), - wherein the modulation element (32) is designed to modulate a magnetic field differently with respect to a circumference of the treadmill shaft (4), and - an evaluation unit (3) which is configured to determine a rotational movement of the pedal shaft (4) based on a sensor signal of the magnetic field sensor (31). [2] Arrangement according to claim 1, wherein the evaluation unit (3) is arranged to determine a rotational speed of the pedal shaft (4) based on the sensor signal of the magnetic field sensor (31). [3] Arrangement according to one of the preceding claims, wherein the evaluation unit (3) is arranged to determine an angular position of the treadle shaft (4) based on the sensor signal of the magnetic field sensor (31). [4] Arrangement according to one of the preceding claims, wherein the magnetic field sensor (31) is arranged for three-axis detection of a magnetic field strength. [5] Arrangement according to one of the preceding claims, wherein the modulation element (32) is formed at least partially from a ferromagnetic material. [6] Arrangement according to claim 5, wherein the modulation element (32) is designed as a sheet metal disc. [7] Arrangement according to claim 6, wherein the modulation element (32) has a plurality of radially projecting regions (32a) distributed around the circumference. [8] Arrangement according to one of the preceding claims, wherein the modulation element (32) is fixed to the pedal shaft (4) and / or to an inner ring (11) of a bottom bracket (10). [9] Arrangement according to one of claims 1 to 7, wherein the modulation element (32) is fixed to a crank (104) which is fixed in a rotationally fixed manner to the pedal shaft (4). [10] Arrangement according to one of the preceding claims, further comprising: - a bottom bracket (10), and - a spring arrangement (2) which is arranged to allow a radial movement of the pedal shaft (4) relative to the housing element (5) against a spring force (20), - wherein the pedal shaft (4) is rotatably mounted relative to the housing element (5) by means of the bottom bracket (10), and - wherein the detection unit is further configured to detect the relative radial movement of the pedal shaft (4) to the housing element (5) based on the sensor signal of the magnetic field sensor (31), and to determine a bearing force (50) on the bottom bracket (10) based on the detected relative radial movement. [11] Bicycle, in particular electric bicycle, comprising an arrangement (1) according to one of the preceding claims.

Images