Relative-rotation measuring device and pedal crank assembly
Patent Information
- Application Number
- EP2023700735
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- Priority Date
- 2022-02-03
- Filing Date
- 2023-01-11
- Publication Date
- 2024-12-11
AI Technical Summary
Current systems for detecting torque in pedal crank assemblies, particularly in e-bikes, face challenges in compactness and structural simplicity, often requiring sensor disks with larger radii or ferritic materials, which are not always feasible.
A device that detects relative rotation between two rotary sections via at least two inelastic coupling elements, which convert relative rotation into axial displacement, allowing for a compact and simple design, using sensor elements to measure this displacement.
Enables efficient and compact measurement of torque in pedal crank assemblies, applicable to various applications, including e-bikes, without the need for ferritic materials or large sensor disks, providing a reliable and cost-effective solution.
Smart Images
Figure 1.1
Abstract
Description
Relative rotation detection device and pedal crank arrangement
[0001] The present disclosure relates to a device for detecting a relative rotation between a first rotating section and a second rotating section, which are spaced apart from each other in a longitudinal direction, wherein the first rotating section is rotatable about a first axis which is arranged parallel to the longitudinal direction and wherein the second rotating section is rotatable about a second axis.
[0002] Furthermore, the present invention relates to a pedal crank arrangement for a muscle-powered vehicle, which has a first crank, a second crank and a detection device of the type described above, wherein the first crank is non-rotatably connected to the first rotating section.
[0003] An example of a converter for measuring torque in a rotating shaft is known from document WO 99 / 05493.
[0004] Document DE 10 2008 027 719 A1 discloses an inductive torque sensor that is permanently installed relative to a vehicle and is designed without wiper springs. It comprises two circuits, each assigned a different angle to be determined.
[0005] Document EP 2 386 844 A1 discloses a torque sensor with a first and a second rotating part. The first rotating part is configured to apply a torque force to it. A [missing information] is located between the first rotating part and the second rotating part. An elastic transmission element is arranged. The first rotating part rotates relative to the second rotating part by a measurable angle of rotation, which can be attributed to the torque force, as a function of the applied torque force.
[0006] Document DE 102018 107416 A1 discloses a further device for determining an angle of rotation and / or a torque.
[0007] Document DE 102020 100 319 A1 concerns a rotary angle sensor for determining a rotary angle and / or a torque.
[0008] In the field of bicycles with assisted motors (e-bikes), it is desirable to detect the torque applied by a rider to the crankset. This torque input from the rider can then be used to control the assisting electric motor.
[0009] Current systems on the market either use a tap to extract the signal from a torsion shaft or detect an angular misalignment of a torsion shaft, which is then converted into a torque. To operate such systems, it is often necessary to place sensor disks on the shaft that have a significantly larger radius than the torsion shaft itself.
[0010] Another way to obtain a signal without contact is to measure the tension of a ferritic shaft. This involves measuring the magnetic flux and converting the change into a torque. A prerequisite for this is that the torsion shaft is made of a ferritic material. Additionally, it is necessary to generate a significant tension to obtain a sufficient signal.
[0011] Against this background, it is an objective of the present disclosure to provide a device for detecting a relative rotation between a first rotating section and a second rotating section, which can be constructed in a simple manner and be compact.
[0012] The above problem is solved by a device for detecting a relative rotation between a first rotating section and a second rotating section, which are spaced apart from each other in a longitudinal direction, wherein the first rotating section is rotatable about a first axis which is arranged parallel to the longitudinal direction, wherein the second rotating section is rotatable about a second axis, wherein the first rotating section and the second rotating section are coupled to each other via at least two first coupling elements which are essentially inelastic in the longitudinal direction and of which at least one is arranged neither coaxial to the first axis nor coaxial to the second axis, such that a relative rotation of the first rotating section and the second rotating section necessarily leads to a relative axial displacement between the first rotating section and the second rotating section, and with a sensor arrangement which detects the axial displacement.
[0013] The basic concept of the present detection device is therefore to design a type of rotation-translation converter that translates a relative rotation between two rotating sections into a relative axial displacement between the two rotating sections. This is achieved via at least two first coupling elements, through which the two rotating sections are coupled to each other. The coupling elements are essentially inelastic in the longitudinal direction, so that a fixed relationship between a relative rotational displacement and a relative axial displacement can be realized. At least the coupling element that is neither coaxial with the first axis nor coaxial with the second axis is preferably designed as an elastically deformable bending element, which is elastically bent when the two rotating sections are rotated relative to each other.Because the coupling element is inelastic in the longitudinal direction, this bending inevitably leads to a relative axial displacement of the two rotating sections. Because the coupling element is elastic in the bending direction, when a force used to generate a relative rotation between the rotating sections is interrupted, it automatically returns to a neutral position. The neutral position is a defined relative position between the two rotating sections, in particular a defined relative rotational position.
[0014] The rotating sections can be, for example, shafts that are rotatably mounted on a housing. The rotating sections can be made of any material. and in particular do not have to be made of a ferritic material. For example, the rotating sections can be made of metal, such as a metal suitable for shaft manufacturing, like steel.
[0015] The sensor arrangement, which detects the axial offset between the rotating sections, can be positioned radially close to the outer circumference of the rotating sections. The sensor arrangement preferably includes a sensor element, which is rigidly fixed to one of the rotating sections, for example as a ring element, and a second sensor element that detects an axial offset of this first sensor element. This allows for a compact design overall.
[0016] Preferably, in the device for detecting relative movement, one of the two rotating sections is axially fixed, so that the relative axial offset is an axial movement of the other rotating section relative to the axially fixed rotating section. It is understood that in this case the sensor arrangement is assigned to the rotating section that is not axially fixed, but is mounted to be movable in the axial direction.
[0017] In general, the disclosed detection device can be used for a variety of applications, namely wherever a torque introduced into a shaft is to be measured.
[0018] A preferred application is a pedal crank arrangement for a muscle-powered vehicle, in particular a bicycle, comprising a first crank, a second crank and a detection device of the disclosed type.
[0019] Typically, the two cranks are connected to a first shaft (crankshaft) that is fixedly connected to one of the two rotating sections. A further shaft, connected to the other rotating section, or, if the detection device has a third rotating section, to that section, may be rigidly connected, for example, to a chainring that is connected to a driven wheel of the vehicle via a chain drive or other traction element (toothed belt). In this case, a torque is introduced into one of the rotating sections via one of the Cranks and an associated crankshaft. The torque is applied via one output to the other rotating section, causing the rotating sections to rotate relative to each other. This rotation corresponds to a torque that is introduced into the pedal crank assembly and is ultimately measured by the sensor arrangement of the detection device, i.e., by measuring a relative axial offset of the rotating sections.
[0020] The muscle-powered vehicle can be assisted by an electric motor. The power provided by an electric motor can be fed into a drive element connected to the first or second rotating section (or to a third rotating section if the detection device has one).
[0021] The first rotary section and the second rotary section preferably have an axial distance of more than 10 mm and less than 60 mm, in particular from 10 mm to 30 mm, and in particular from 15 mm to 25 mm.
[0022] This axial distance essentially corresponds to the axial length of the first coupling elements when they are aligned parallel to the longitudinal direction.
[0023] Preferably the number of first coupling elements is greater than 4 and less than 25, in particular greater than 6 and less than 20, preferably greater than 6 and less than 16, and in particular in a range of 8 to 12.
[0024] It is particularly preferred if all first coupling elements are arranged neither coaxially to the first axis nor coaxially to the second axis.
[0025] The first axis and the second axis are preferably coaxial to each other, but can also be offset parallel to each other.
[0026] The first rotation section and the second rotation section can preferably be rotated relative to each other within an angular range that is greater than 5° and less than 65°. The angular range over which the rotation sections can be rotated relative to each other is particularly preferred, within a range of 30° to 60°.
[0027] The maximum angle of rotation can either result from the maximum inherent elasticity of the coupling elements, or it can be set by a rotation angle stop.
[0028] Preferably, the rotary sections connected to each other via the first coupling elements result in a relative maximum axial offset in a range of 5 mm to 25 mm, preferably in a range of 10 mm to 25 mm.
[0029] It is understood that the aforementioned dimensions and numerical specifications refer to the mounting of the detection device in a crank assembly of a bicycle or similar. For other mounting configurations, other dimensions may be preferable depending on the torques involved and other boundary conditions.
[0030] The first and / or the second rotating section is preferably each mounted on a housing by means of a radial bearing, which may, for example, be a rolling bearing. One of the rotating sections is also preferably axially supported, ideally by the same bearing, which is, for example, designed as a radial / axial bearing. The other rotating section is preferably mounted to be axially displaceable.
[0031] The task is thus completely solved.
[0032] It is particularly advantageous if the first coupling elements each have a first end that is firmly connected to the first rotating section and a second end that is firmly connected to the second rotating section.
[0033] It is particularly advantageous if the first ends of the first coupling elements are arranged on a circle coaxial with the first axis and / or if the The second ends of the first coupling elements are arranged on a circle coaxial with the second axis.
[0034] The circle on which the respective ends of the coupling elements are arranged can, for example, have a diameter in a range of 10 mm to 25 mm, in particular in a range of 12 mm to 20 mm.
[0035] This information also refers to a preferred application in a pedal crank arrangement.
[0036] In the detection device described so far, one of the rotating sections is preferably fixed axially, while the other rotating section is mounted to be axially displaceable. This can entail additional design costs, particularly if the axially displaceable rotating section is to be connected to other elements in a crank assembly or the like. The bearing arrangement can also be more complex, especially on the side of the other rotating section.
[0037] According to a particularly preferred embodiment, the detection device therefore has a third rotary section which is rotatable about a third axis which is arranged parallel to the longitudinal direction and which is coupled to the second rotary section via at least two second coupling elements which are essentially inelastic in the longitudinal direction and of which at least one is arranged neither coaxially to the third axis nor coaxially to the second axis, such that a relative rotation of the third rotary section and the second rotary section necessarily leads to a relative axial displacement in the longitudinal direction between the third rotary section and the second rotary section.
[0038] In this embodiment, it is possible to clamp both the first and third rotary sections rigidly in the axial direction, i.e., to mount them axially. Preferably, in this embodiment, the first and third rotary sections are also radially mounted to a housing by means of radial bearings. In this preferred case, the second rotary section is freely movable between the first and third rotary sections. The second rotating section is connected to the first rotating section via the first coupling elements, and to the third rotating section via the second coupling elements. In this case, the sensor arrangement is still assigned to the second rotating section.
[0039] In this embodiment, a relative rotation between the first and third rotational sections inevitably leads to an axial offset of the second rotational section, which can be detected by means of the sensor arrangement.
[0040] In this embodiment, a relative rotation between the first rotation section and the third rotation section is therefore detected by detecting an axial offset of the second rotation section.
[0041] In some embodiments, the second rotating section can be rotated relative to the first or third rotating section. In other embodiments, however, it is conceivable that the second rotating section does not rotate relative to the first and third rotating sections. This applies in particular if the coupling of the second and first rotating sections via the first coupling elements and the coupling of the second and third rotating sections via the second coupling elements are symmetrical with respect to a radial plane that passes through the second rotating section.
[0042] According to a particularly preferred embodiment, the second coupling elements each have a first end that is fixedly connected to the third rotating section and a second end that is fixedly connected to the second rotating section.
[0043] It is particularly advantageous if the first ends of the second coupling elements are arranged on a circle coaxial with the third axis and / or if the second ends of the second coupling elements are arranged on a circle coaxial with the second axis.
[0044] The diameter of the circle of the second coupling element is preferably identical to the diameter of the circle of the first coupling elements.
[0045] The third axis is preferably arranged coaxially with the second axis and coaxially with the first axis. In other words, all three rotating sections are arranged coaxially with a single axis.
[0046] The coupling elements can generally have any shape. However, it is particularly advantageous if the first coupling elements are rod-shaped and / or the second coupling elements are also rod-shaped.
[0047] The rod-shaped elements can, for example, have a diameter in the range of 0.5 mm to 5 mm, preferably in the range of 0.8 mm to 2.5 mm.
[0048] The coupling elements are preferably made of spring steel. The connection to the rotating sections can be made in any way, e.g., by welding. In other variants, the coupling elements are formed integrally with the respective rotating section, for example, by 3D printing ("additive manufacturing").
[0049] The coupling elements, in the form of rod-shaped elements, can each be aligned parallel to the longitudinal axis in a basic position.
[0050] However, it is particularly advantageous if the first rod-shaped elements are arranged in a basic position at a first oblique angle to the first axis and to the second axis, and / or if the second rod-shaped elements are arranged in a basic position at a second oblique angle to the third axis and to the second axis.
[0051] As a result, the coupling elements already have a skew position in their basic position, so that changes in the angle of rotation immediately lead to a larger axial offset.
[0052] The first inclined angle and / or the second inclined angle can preferably be in a range of 5° to 30° with respect to the longitudinal axis.
[0053] It is understood that the deflection in the form of a relative rotation corresponds to a deflection starting from the respective basic position, i.e., starting from positions where the first rod-shaped elements are already arranged at an angle.
[0054] It is also particularly advantageous if the first coupling elements and the second coupling elements are essentially mirrored with respect to a radial plane passing through the second rotation section, such that the first rotation section and the third rotation section can be rotated relative to each other without the first rotation section and the third rotation section being necessarily axially offset relative to each other.
[0055] In this embodiment, as described above, the first rotating section and the third rotating section can be axially supported.
[0056] The sensor arrangement can be configured as a displacement sensor in any way desired.
[0057] It is particularly advantageous if the sensor arrangement has a first sensor section and a second sensor section, wherein the first sensor section is fixed to the second rotating section and wherein the second sensor section is fixed to a housing.
[0058] The first sensor section preferably has a magnet, in particular in the form of a ring magnet, which is arranged coaxially around the axis of the second rotating section.
[0059] The second sensor section has at least one Hall sensor or an inductive sensor, which is preferably fixed to the housing and which detects an axial displacement of the first sensor section.
[0060] The second sensor section preferably has at least two sensor elements arranged on axially opposite sides of the first sensor section.
[0061] This allows for highly secure data collection.
[0062] It is particularly advantageous if the two sensor elements are connected in a bridge circuit.
[0063] The signal for detecting the axial offset can be amplified in this process.
[0064] According to a further preferred embodiment, the first sensor has an incremental section by means of which a rotation of the second rotation section can be detected.
[0065] In this embodiment, the detection device makes it possible not only to detect the relative rotation of the first and second rotating sections, but also to detect the angular velocity and consequently the relative rotational position of the second rotating section. Furthermore, since the second rotating section is connected to the first and third rotating sections over a limited angular range in the direction of rotation, it is also possible to detect the angular velocity of these rotating sections.
[0066] Preferably, the outer circumference of a ring-shaped magnet is designed in the manner of a gear or the like.
[0067] The rotational speed of the rotating sections can be determined via the angular velocity. In some cases, an absolute rotational position can also be determined. In particular If the rotational position of a crank in a pedal crank assembly is known and the incremental encoder assumes a fixed rotational position relative to that crank, then an absolute rotational position of that crank can also be deduced via an incremental encoder.
[0068] It is understood that the features mentioned above and those to be explained below can be used not only in the combinations specified, but also in other combinations or on their own, without leaving the scope of the present invention.
[0069] Exemplary embodiments of the invention are shown in the drawing and are explained in more detail in the following description. They show: Figure 1 shows a perspective partial view of an embodiment of a pedal crank arrangement with a device for detecting a relative rotation; Figure 2 shows a longitudinal sectional view through the pedal crank arrangement of Fig. 1 in a basic position; Figure 3 shows a sectional view along a line III-III in Fig. 2; Figure 4 shows a longitudinal section view through the pedal crank arrangement of Fig. 1, after a relative rotation of two rotating sections; Figure 5 shows a sectional view along a line VV in Fig. 4; Figure 6 shows a perspective view of another embodiment of a pedal crank arrangement with a further embodiment of a device for detecting a relative rotation; Figure 7 shows a longitudinal sectional view through the pedal crank arrangement of Fig. 6 in a basic position; Figure 8 shows a sectional view of the pedal crank assembly of Figures 6 and 7 after a relative rotation of two rotating sections; and Figure 9 shows a schematic representation of a sensor arrangement for a detection device.
[0070] Figures 1 to 5 show a first embodiment of a pedal crank arrangement T for a vehicle, in particular a bicycle, in particular an e-bike, with a first embodiment of a device 10 for detecting a relative rotation of two rotating sections.
[0071] The pedal crank assembly T comprises a first crank K1 and a second crank K2, which are arranged in a manner known per se, offset by 180° with respect to a pedal crank shaft (not shown in detail). A preferred drive direction is designated by R. The drive direction R is the direction in which the pedal crank assembly is set in rotation to propel the associated vehicle. Typically, a rotation opposite to the drive direction is also possible due to a freewheel or similar mechanism, but without affecting the propulsion of the vehicle.
[0072] The detection device 10 comprises a first rotary section 12, which is arranged coaxially to a first axis 14 and radially mounted on a housing 34 by means of a first radial bearing 15. Furthermore, the detection device 10 comprises a second rotary section 16, which is arranged coaxially to a second axis 18 and radially mounted on the housing 34 by means of a second radial bearing 19.
[0073] The first axis 14 and the second axis 18 are aligned parallel to a longitudinal direction 20, which is parallel to a crank axle. The first axis 14 and the second axis 18 are arranged coaxially with each other in this case, but can also be arranged offset from each other.
[0074] The first rotating section 12 is also axially supported by means of a schematically indicated axial bearing 22, which, for example, forms a shoulder on the first rotating section. The first rotating section 12 has a section 12 and an axial retaining ring that engages in a groove of the first rotating section 12, wherein the first rotating section 12 is rigidly connected to a first part of a radial bearing 15, which is fixed between the shoulder and the axial retaining ring. The radial bearing is preferably a rolling bearing that can also absorb axial forces. A second part of the radial bearing 15 is fixed axially and radially to the housing 34 of the detection device 10. The housing 34 can also be a housing of the crank assembly T.
[0075] The second rotary section 16 is radially mounted in relation to the housing 34 by means of the second radial bearing 19, but axially displaceable in relation to the housing 34.
[0076] The first rotating section 12 is, for example, non-rotatably connected to a first crank K1.
[0077] In Figures 1-5, the second rotating section 16 is shown with the second crank K2. The crank assembly T is connected. In other cases, however, the second rotating section 16 can also be non-rotatably connected to another shaft of the crank assembly, wherein the other shaft is, for example, directly or indirectly connected to a chainring or a pulley of a traction transmission for driving a driven wheel of the vehicle.
[0078] The detection device 10 serves to detect a relative rotation of the first rotary section 12 and the second rotary section 16. For this purpose, the detection device 10 includes a number of first connecting rods 24, each having a first end 25a and a second end 25b. The first ends 25a are rigidly connected to the first rotary section 12. The second ends 25b are rigidly connected to the second rotary section 16. More precisely, the connecting rods are designed as essentially inelastic rods in the longitudinal direction, but which can be bent in a cantilever-like manner relative to their respective connection with the first rotary section 12 and the second rotary section 16, respectively.
[0079] Figures 1 to 3 show that the first connecting rods 24 are each aligned parallel to the longitudinal direction 20. The first connecting rods 24 are arranged neither coaxially to the first axis 14 nor coaxially to the second axis 18. Rather, the first ends 25a are arranged on a circle, spaced evenly apart from each other, as shown in Figure 3. The circle has a diameter D, which can be in a range of 10 to 25 mm, particularly in a range of 12 to 20 mm.
[0080] In this case, the number of first connecting rods 24 is exactly 10 (ten). In other words, the first connecting rods 24 are evenly spaced from each other at 36° intervals around the circumference. However, the number of first connecting rods 24 can generally be in a range of 5 to 20, and in particular in a range of 8 to 12.
[0081] The first coupling elements 24 are all arranged eccentrically to the first axis 14 and the second axis 18.
[0082] The first rotating section 12 and the second rotating section 16 are coupled to each other in a basic position by the plurality of first coupling rods 24, as shown in the Fig. Figures 1 to 3 are shown. In the basic position, the first connecting rods 24 are not elastically deflected.
[0083] Figures 4 and 5 show a position in which the second rotary section 16 is rotated relative to the first rotary section 12 by an angle α. As can be seen particularly in Figure 4, this causes the first connecting rods 23 to be deflected obliquely, so that they are each arranged at an oblique angle with respect to the longitudinal direction 20, this oblique angle being shown at β in Figure 4. Such oblique angles are always measured when viewed perpendicular to the respective axis 14, 16, etc.
[0084] It is understood that the ends 25a, 25b, which are not shown in detail in Figs. 4 and 5 for the sake of clarity, still protrude vertically from the respective rotation sections 12 and 16, respectively, and that the coupling rods are located in the area between them. However, they are deflected, so that they are skew in relation to axes 14 and 16.
[0085] In Fig. 3, a connecting rod 24a is shown by way of example in the assumed basic position at 0°, i.e. in a position in which the crank K2 points vertically upwards by way of example.
[0086] In the comparative representation of Fig. 5, the crank K2' is deflected by the angle a corresponding to approximately 36°, so that the connecting rod 24a, which is shown at 0° in Fig. 3, is now positioned at approximately 36° (= a), as shown in Fig. 5 at 24a'.
[0087] The first connecting rods 24 are made of a spring-elastic material, for example, spring steel or the like. Consequently, a relative rotation between the first rotating section 12 and the second rotating section 16 can only occur if a moment is applied to one of the rotating sections 12, 16, which is supported in some way by the other rotating section. The applied moment then leads to the relative rotation of the rotating sections 12, 16, during which the first connecting rods 24 are elastically deflected. As soon as the torque is no longer present, the detection device 10 returns to its initial position, as shown in Figures 2 and 3, due to the elasticity of the first connecting rods 24.
[0088] The rotation of the rotary sections 12, 16 changes the relative distance between the rotary sections 12, 16, due to the fact that the first coupling elements 24 are essentially inelastic in the longitudinal direction. This leads to an axial displacement A of the second rotary section 16, since the first rotary section 12 is axially supported.
[0089] The axial length of the first coupling elements 24 is in a range of 10 mm to 60 mm, in particular in a range of 10 mm to 30 mm.
[0090] The detection device 10 further includes a sensor arrangement 26. The sensor arrangement 26 has a first sensor section 28 in the form of a magnetic sensor- The sensor wheel 28 is fixedly connected to the second rotating section 16. The sensor wheel of the first sensor section 28 can have a smooth outer circumference. Preferably, however, the sensor wheel 28 is configured with an incremental section 30, wherein the sensor wheel has a plurality of teeth, as can be seen in Figures 3 and 5.
[0091] Fig. 2 shows that the first sensor section 28 is in an axial neutral position N in the basic position.
[0092] After a rotation of the rotary sections 12, 14, the second rotary section 16 moves towards the first rotary section 12, so that the relative rotation of the rotary sections 12, 16 results in an axial offset of the second rotary section 16, as shown in Fig. 4 at A (as the difference of a path to the neutral position N, as shown in Fig. 2).
[0093] The sensor arrangement 26 further includes a second sensor section 32, which is fixed to the housing 34. The second sensor section 32 is designed to measure the axial displacement A. The second sensor section 32 can, for example, be a Hall sensor or an inductive sensor.
[0094] However, it is generally possible to use any other type of sensor. In any case, the detection of the axial displacement A is preferably contactless, with the second sensor section 32 being electrically connected to a power supply via the housing 34. The first sensor section 28, however, is preferably a passive sensor section, such as a magnetic sensor section, so that it is not necessary to supply the first sensor section 28 with power. Therefore, it is not necessary to provide sliding contacts.
[0095] As shown in Figs. 2 and 4, the second sensor section 32 is preferably bow-shaped and surrounds the first sensor section 28, such that the second sensor section 32 can contain two sensor elements, as will be explained below.
[0096] In the embodiment of Figs. 1 to 5, the detection device 10 has two rotary sections 12, 16, one of which is axially fixed and the other of which is axially displaceable relative to the other.
[0097] Figures 6 to 8 show a further embodiment of a detection device 10A, which generally corresponds to the detection device described above and has the first rotary section 12 and a second rotary section 16A, which are coupled to each other via a plurality of first coupling rods 24A, similar to the first embodiment.
[0098] The detection device 10A additionally has a third rotary section 40, which is rotatably mounted on the housing about a third axis 42 (see Fig. 7) by means of a third radial bearing 44 with respect to the housing 34A. The third axis can be radially offset from the second axis 18, but is preferably arranged coaxially with it.
[0099] The third rotating section 40 is axially supported in relation to the housing 34A by means of a further axial bearing 46, just as the first rotating section 12 is axially supported in relation to the housing 34A by means of the axial bearing 22.
[0100] The third rotating section 40 is coupled to the second rotating section 16A via a plurality of second coupling rods 48, which are constructed in the same way as the first coupling rods 24A.
[0101] More precisely, the first ends 49a of the second coupling rods 48 are firmly connected to the third rotating section 40, and the second ends 49b of the second coupling elements 48 are firmly connected to the second rotating section 16A.
[0102] Just like the first coupling elements 24A, the second coupling elements 48 are arranged with their respective ends on a circle that is coaxial to the respective axis 18A, 42.
[0103] The third axis 42 is preferably designed coaxially with the second axis 18A and the first axis 14, as is also shown in Figs. 6 to 8.
[0104] In the detection device 10A of Figures 6 to 8, the first coupling rods 24A and the second coupling rods 48 are arranged in the basic position shown, each at an oblique angle relative to the first axis 14. More precisely, the first coupling elements 24A and the second coupling elements 48 are essentially mirror images of each other with respect to a radial plane passing through the second rotating section 18A, such that the oblique angles β1 of the first coupling elements 24A are identical in magnitude to the oblique angle β2 of the second coupling elements 48, but with a different sign.
[0105] The first rotary section 12 and the third rotary section 40 are rotatable relative to each other without the first rotary section 12 and the third rotary section 40 being necessarily axially offset relative to each other.
[0106] Rather, such a relative rotation between the first rotating section 12 and the third rotating section 40 necessarily results in an axial displacement of the second rotating section 16A with respect to the housing, which can be detected by means of a sensor arrangement 26, which can be constructed similarly to the embodiment of Figs. 1 to 5.
[0107] Fig. 8 schematically illustrates such an axial displacement A. Here, the rotation of the first rotating section 12 and the third rotating section 40 has caused the first coupling elements 24A to align more straight, resulting in a change to the first inclined angle βT of 0°. Conversely, the inclined angle β2' of the second coupling rods 48 has increased. As a result, the second rotating section 16A has moved away from the first rotating section 12 in the longitudinal direction 20 and closer to the third rotating section 40 in the longitudinal direction 20.
[0108] This makes it possible to mount both the first rotating section 12 and the third rotating section 40 in the axial direction, thus simplifying their proximity to other components of the crank assembly or a bicycle. The second rotating section 16A is preferably suspended completely freely between the rotating sections 12 and 40 by means of the first connecting rods 24A and the second connecting rods 48.
[0109] Fig. 9 shows a preferred embodiment of a sensor arrangement 26.
[0110] The sensor arrangement 26 includes a first sensor section 28 in the form of a sensor wheel, similar to the embodiments described above. The sensor wheel 28 is preferably equipped with an incremental section 30 on its outer circumference.
[0111] The second sensor section 32 is designed as a bracket that overlaps the first sensor section 28. A first sensor element 50 and a second sensor element 52 are attached to the second sensor section 32, specifically on axially opposite sides of the first sensor section 28.
[0112] The sensor elements 50, 52 can, for example, be Hall sensors powered by a supply voltage Vs and connected to an unspecified ground terminal. Furthermore, each of the sensor elements outputs a voltage Vi or V2 depending on its proximity to the sensor wheel 28, which is supplied to an evaluation unit 54, for example, a bridge circuit for amplifying the sensor signal. The evaluation unit 54 outputs the rotation angle a measured by means of the axial offset A. Preferably, the evaluation unit 54 also outputs an angular velocity w, or a rotational speed proportional thereto, or a relative or absolute rotational position of the second rotating section 16A. Reference symbol list: 10 Device for detecting relative rotation 12 first shooting section 14 first axis 15 first radial bearing 16 second shooting section 18 second axis 19 second radial bearing 20 Longitudinal direction 22 Axial bearing (12) 24 first coupling rods 25a first end 25b second end 26 Sensor arrangement 28 first sensor section (sensor wheel) 30 incremental section 32 second sensor section 34 cases 40 third rotation section 42 third axis 44 third radial bearing 46 additional axial bearings 48 second coupling rods 49a first end 49b second end 50 first sensor element 52 second sensor element 54 Evaluation unit / bridge circuit T crank arrangement for a bicycle K1 Crank 1 K2 Crank 2 R Drive direction of rotation D Diameter of circle (24) Axial offset a Rotation angle 12 / 16 ß Inclination angle 24 ß1 First inclined angle 24A ß2 Second inclined angle 48 w Angular velocity / Speed / Rotational position
Claims
Claims Device (10) for detecting a relative rotation between a first rotating section (12) and a second rotating section (16), which are spaced apart from each other in a longitudinal direction (20), - wherein the first rotation section (12) is rotatable about a first axis (14) which is arranged parallel to the longitudinal direction (20), - wherein the second rotating section (16) is rotatable about a second axis (18), - wherein the first rotating section (12) and the second rotating section (16) are coupled to each other via at least two first coupling elements (24) which are essentially inelastic in the longitudinal direction (20) and of which at least one is arranged neither coaxially to the first axis (14) nor coaxially to the second axis (18), such that a relative rotation of the first rotating section (12) and the second rotating section (16) necessarily leads to a relative axial displacement (A) between the first rotating section (12) and the second rotating section (16), and - with a sensor arrangement (26) that detects the axial displacement (A). Detection device according to claim 1, wherein the first coupling elements (24) each have a first end (25a) that is fixedly connected to the first rotating section (12) and a second end (25b) that is fixedly connected to the second rotating section (16). Detection device according to claim 2, wherein the first ends (25a) of the first coupling elements (24) are arranged on a circle coaxial with the first axis (14) and / or wherein the second ends (25b) of the first coupling elements (24) are arranged on a circle coaxial with the second axis (16). Detection device according to one of claims 1-3, wherein the detection device (10) has a third rotary section (40) which is rotatable about a third axis (42) which is arranged parallel to the longitudinal direction (20) and which is coupled to the second rotary section (16) via at least two second coupling elements (48) which are essentially inelastic in the longitudinal direction (20) and of which at least one is arranged neither coaxially to the third axis (42) nor coaxially to the second axis (18), such that a relative rotation of the third rotary section (40) and the second rotary section (16) necessarily leads to a relative axial offset (A) in the longitudinal direction between the third rotary section (40) and the second rotary section (16).Detection device according to claim 4, wherein the second coupling elements (48) each have a first end (49a) that is fixedly connected to the third rotating section (40) and a second end (49b) that is fixedly connected to the second rotating section (16). Detection device according to claim 5, wherein the first ends (49a) of the second coupling elements (48) are arranged on a circle coaxial with the third axis (42) and / or wherein the second ends (49b) of the second coupling elements (48) are arranged on a circle coaxial with the second axis (18). Detection device according to any one of claims 1 to 6, wherein the first coupling elements (24) are first rod-shaped elements and / or wherein the second coupling elements (46) are second rod-shaped elements.Detection device according to claim 7, wherein the first rod-shaped elements (24A) are arranged in a basic position at a first oblique angle (ß1) to the first axis (14) and to the second axis (18) and / or wherein the second rod-shaped elements (48) are arranged in a basic position at a second oblique angle (ß2) to the third axis (42) and to the second axis (18). A detection device according to claim 7 or 8, wherein the first coupling elements (24A) and the second coupling elements (48) are substantially mirror images of each other with respect to a radial plane passing through the second rotating section (18), such that the first rotating section (12) and the third rotating section (40) are rotatable relative to each other without the first rotating section (12) and the third rotating section (40) being forcibly axially displaced relative to each other. A detection device according to any one of claims 1 to 9, wherein the sensor arrangement (26) comprises a first sensor section and a second sensor section (42), wherein the first sensor section (28) is fixed to the second rotating section (16; 16A) and wherein the second sensor section (32) is fixed to a housing (34).A detection device according to claim 10, wherein the first sensor section (28) comprises a magnet and / or wherein the second sensor section (32) comprises at least one Hall sensor or inductive sensor. A detection device according to claim 10 or 11, wherein the second sensor section (32) comprises at least two sensor elements (50, 52) arranged on axially opposite sides of the first sensor section (28). A detection device according to claim 12, wherein the two sensor elements (50, 52) are connected in a bridge circuit (54). A detection device according to any one of claims 10-13, wherein the first sensor section (28) comprises an incremental section (30) by means of which a rotation of the second rotary section (16; 16A) can be detected.Pedal crank arrangement for a muscle-powered vehicle comprising a first crank (K1), a second crank (K2) and a detection device (10) according to one of claims 1 - 14, wherein the first crank (K1) is rotationally fixed. is connected to the first rotating section (12) and wherein the second crank (K2) rotates with the second rotating section (16) or, if the detection device (10) has a third rotating section (40), is connected to the third rotating section (40).