Measuring device and method for ascertaining operating parameters at shafts

Abstract

Measuring devices and methods for ascertaining an operating parameter at a shaft are disclosed. The shaft may be supported by at least one bearing. In one example, the measuring device includes at least one first sensor element configured to detect an absolute angle of the shaft and at least one second sensor element configured to detect a change in a distance of the shaft from the at least one second sensor element. A computing device may be configured to calculate one or more operating parameters at the shaft from the absolute angle of the shaft and the change in the distance.

Claims

1. A measuring device for ascertaining an operating parameter at a shaft, the shaft being supported by at least one bearing, the measuring device comprising: at least one first sensor element configured to detect an absolute angle of the shaft; at least one second sensor element configured to detect a change in a distance of the shaft from the at least one second sensor element; and a computing device configured to calculate one or more operating parameters at the shaft from the absolute angle of the shaft and the change in the distance.

2. The measuring device as claimed in claim 1, wherein, for the detection of the absolute angle, an encoder is arranged radially on the shaft or radially on a component rotationally fixedly connected to the shaft.

3. The measuring device as claimed in claim 2, wherein the rotationally fixedly connected component is an extension of an inner ring of the bearing.

4. The measuring device as claimed in claim 1, wherein, for the detection of the absolute angle, an encoder is arranged axially on the shaft or axially on a component rotationally fixedly connected to the shaft.

5. The measuring device as claimed in claim 4, wherein the rotationally fixedly connected component is an inner ring of the bearing or a seal.

6. The measuring device as claimed in claim 1, wherein the at least one bearing has a bearing point, and wherein the at least one second sensor element is arranged at the bearing point.

7. The measuring device as claimed in claim 1, wherein the at least one bearing has a first and a second bearing point, wherein the measuring device comprises at least two second sensor elements, and wherein one each of the second sensor elements is arranged at the first and the second bearing point.

8. The measuring device as claimed in claim 1, wherein the at least one bearing has a first and a second bearing point, and wherein the at least one second sensor element is arranged between the first and the second bearing point.

9. The measuring device as claimed in claim 8, wherein the at least one second sensor element is arranged centrally between the first and the second bearing point.

10. The measuring device as claimed in claim 1, wherein the at least one first sensor element and/or the at least one second sensor element are/is formed as an eddy current sensor.

11. The measuring device as claimed in claim 1, wherein the at least one first sensor element and the at least one second sensor element are integrated structurally in one sensor unit.

12. A method for ascertaining an operating parameter at a shaft, wherein a force can be introduced into the shaft via at least one crank arm rotationally fixedly connected to the shaft, wherein the force can be broken down into a tangential force and a radial force, wherein a line of action of the radial force is directed toward a center of the shaft, and wherein a line of action of the tangential force forms a right angle with the line of action of the radial force, the method comprising: detecting an absolute angle of the shaft; detecting a change in a distance of the shaft from a sensor element; and calculating the operating parameter at the shaft from the absolute angle and the change in the distance, wherein the force is calculated from the change in the distance, wherein the tangential force is calculated from the force and the absolute angle, and wherein the operating parameter at the shaft is determined by the tangential force.

13. A measuring device for ascertaining a torque or a power at a shaft of a bottom bracket bearing arrangement of a bicycle or electric bicycle, the shaft being supported by a bearing, the measuring device comprising: a first sensor element configured to detect an absolute angle of the shaft; a second sensor element configured to detect a change in a distance of the shaft from the second sensor element; and a computing device configured to calculate the torque or the power at the shaft from the absolute angle of the shaft and the change in the distance.

14. The measuring device as claimed in claim 13, wherein, for the detection of the absolute angle, an encoder is arranged radially on the shaft or radially on a component rotationally fixedly connected to the shaft.

15. The measuring device as claimed in claim 13, wherein, for the detection of the absolute angle, an encoder is arranged axially on the shaft or axially on a component rotationally fixedly connected to the shaft.

16. The measuring device as claimed in claim 13, wherein the bearing has a bearing point, and wherein the second sensor element is arranged at the bearing point.

17. The measuring device as claimed in claim 13, wherein the bearing has a first and a second bearing point, wherein the measuring device comprises at least two second sensor elements, and wherein one each of the second sensor elements is arranged at the first and the second bearing point.

18. The measuring device as claimed in claim 13, wherein the bearing has a first and a second bearing point, and wherein the second sensor element is arranged between the first and the second bearing point.

19. The measuring device as claimed in claim 13, wherein the first sensor element and/or the second sensor element are/is formed as an eddy current sensor.

20. The measuring device as claimed in claim 13, wherein the first sensor element and the second sensor element are integrated structurally in one sensor unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In the following, an example embodiment of the disclosure will be illustrated using the figures. The figures show non-scaled drawings, in which:

[0033] FIG. 1 shows a basic sketch of forces acting in a bottom bracket bearing arrangement,

[0034] FIG. 2 shows possible codes for a radial and an axial encoder for detecting the absolute angle of a shaft, and

[0035] FIG. 3 shows a basic illustration relating to detecting the deflection of a shaft of a bottom bracket bearing arrangement.

DETAILED DESCRIPTION

[0036] FIG. 1 shows a basic sketch of forces acting in a bottom bracket bearing arrangement. The dashed circular line 101 shows the circular path of a crank pedal (not shown) of a crank arm (not shown) around the center M of a bottom bracket shaft (not shown). The circle related to the circular line 101 has the radius 103. The pedal force F_p 110 is introduced into the bottom bracket shaft via the crank pedal and the crank arm. The direction 105 shows the direction of circulation of the crank pedal and of the crank arm about the bottom bracket shaft. Expressed in other words, it shows the direction of the circulation of an introduction of force along the circular line 101 (however, the vector direction of the actual pedal force is not to be understood hereby). The pedal force F_p 110 can be broken down into a radial force F_r 120 and a tangential force F_t 130. Radial force F_r 120 and tangential force F_t 130 are at right angles to each other. The absolute angle beta results from the force parallelogram consisting of the designations 120, 121, 130, 131 and of the projected force vector of the pedal force F_p 111. This angle beta 150 is identical to the absolute angle beta 151 of the crank arm with the radius line 103 illustrated. This radius line 103 extends parallel to the vector direction of the pedal force F_p 110. Thus, by measuring the actual absolute angle beta 151 of the crank arm, the absolute angle beta 150 in the force parallelogram can also be ascertained. Such an actual measurement of the actual absolute angle beta 151 is possible, for example, by using a sensor element such as an eddy current sensor for detecting an encoder on the bottom bracket bearing shaft having a code according to FIG. 2.

[0037] FIG. 2 shows possible codes for a radial and an axial encoder for detecting the absolute angle of a shaft. Thus, a wedge-shaped code 210 and a sinusoidal code 220 for a radial encoder are illustrated. A corresponding variant 230 for an axial code is also shown for an axial encoder.

[0038] FIG. 3 shows a basic illustration relating to the detection of the deflection of a shaft 310 of a bottom bracket bearing arrangement 300. The shaft 310 is rotationally fixedly connected at its axial ends to a first crank arm 312 and a second crank arm 314. The first crank arm 312 has a pedal axis 313, the second crank arm 314 correspondingly has a pedal axis 315. The shaft 310 is mounted via a first bearing point 322 and a second bearing point 324. A pedal force F_p, which can be introduced into the shaft 310, for example by crank pedals on the pedal axes 313, 315 via the first and second crank arm, leads to deflection and displacement of the shaft 310. The deflection is illustrated by the dashed line 335. Such bending of the shaft 310 leads, for example, to a change in the eddy currents in an eddy current measurement (not illustrated). The torque acting on the shaft 310 is transferred to the chain ring 360 rotationally fixedly connected to the shaft 310.

LIST OF DESIGNATIONS

[0039] 101 Circular line of a circle [0040] 103 Radius of the circle [0041] 105 Direction of circulation of an introduction of force along the circular line [0042] M Center of the circle [0043] 110, 111 Pedal force/force F_p [0044] 120, 121 Radial force F_r [0045] 130, 131 Tangential force F_t [0046] 150 Absolute angle beta [0047] 210 Wedge-shaped code for radial encoder [0048] 220 Sinusoidal code for radial encoder [0049] 230 Code for axial encoder [0050] 300 Bottom bracket bearing arrangement [0051] 310 Shaft [0052] 312 Left-hand crank arm [0053] 313 Left-hand pedal axis [0054] 314 Right-hand crank arm [0055] 315 Right-hand pedal axis [0056] 322 Left-hand bearing point [0057] 324 Right-hand bearing point [0058] 330 Force F [0059] 335 Possible deflection of the shaft upon introduction of force [0060] 360 Chain ring