SYSTEM FOR TORQUE MEASUREMENT AND METHOD

Abstract

The invention relates to a system for torque measurement, in particular at a drive of an e-bike, including at least one shaft which is rotatable about an axis, is magnetized in at least one axial partial section, and onto which a torque to be measured can be applied, at least one TMR sensor, which is situated outside the shaft and is designed for at least two-dimensionally, in particular three-dimensionally, measuring a magnetic field and which is arranged in relation to the at least one partial section in such a way that, when the shaft rotates about the axis, the at least one sensor measures a change of the magnetic field due to the magnetostrictive effect in the magnetized partial section when the torque acts on the shaft, and an evaluation unit, which is connected to the at least one TMR sensor and is designed for determining a torque acting on the shaft based on the measured values of the magnetic field.

Claims

1-9. (canceled)

10. A system for torque measurement at a drive of an e-bike, comprising: at least one shaft, which is rotatable about an axis, magnetized in at least one axial partial section, and onto which a torque to be measured can be applied; at least one TMR sensor arranged outside the shaft, and configured to measure, at least two-dimensionally, a magnetic field and which is arranged in relation to the magnetized at least one axial partial section in such a way that, when the shaft rotates about the axis, the at least one TMR sensor measures a change of the magnetic field due to the magnetostrictive effect in the magnetized at least on axial partial section when the torque acts on the shaft; and an evaluation unit connected to the at least one TMR sensor, and configured to determine a torque acting on the shaft based on measured values of the magnetic field.

11. The system as recited in claim 10, wherein the TMR sensor is configured to measure the magnetic field three-dimensionally.

12. The system as recited in claim 10, wherein the shaft includes at least two axial partial sections, which are magnetized.

13. The system as recited in claim 12, wherein the at least two axial partial sections have different magnetizations.

14. The system as recited in claim 12, wherein the at least two axial partial sections have opposite magnetizations.

15. The system as recited in claim 12, wherein the at least one TMR sensor includes multiple TMR sensors, at least one of the TMR sensors being assigned to each respective partial section of the at least two partial sections.

16. The system as recited in claim 12, wherein the at least two axial partial sections are arranged adjacent to each other.

17. The system as recited in claim 15, wherein each the at least one TMR sensors assigned to the respective axial partial sections is arranged axially centrally with respect to the respective axial partial section.

18. The system as recited in claim 15, wherein sensors of the multiple TMR sensor assigned to at least two adjacent partial sections are arranged closer to one another in an axial direction than a sum of the halves of axial extensions of the at least two adjacent partial sections.

19. The system as recited in claim 10, wherein the at least one TMR sensor is an ASIC.

20. A method for torque measurement at a drive of an e-bike, comprising the following steps: magnetizing at least one axial partial section of at least one shaft which is rotatable about an axis; rotating the shaft about the axis; at least two-dimensionally measuring a change of a magnetic field in the magnetized at least one axial partial section using at least one TMR sensor, the change of the magnetic field being due to a magnetostrictive effect during the rotation of the shaft about the axis; evaluating measured values of the at least one TMR sensor using an evaluation unit; and determining a torque acting on the shaft based on the evaluated measured values.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 shows a schematic representation of a conventional system.

[0028] FIG. 2 shows a schematic representation of a system according to one specific example embodiment of the present invention.

[0029] FIG. 3 shows a schematic representation of a system according to one specific example embodiment of the present invention.

[0030] FIG. 4 shows a schematic representation of steps of a method according to one specific example embodiment of the present invention.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

[0031] FIG. 1 shows a conventional system.

[0032] In detail, FIG. 1 shows a system 1, which includes a shaft 3, which is rotatable about an axis 2. Moreover, shaft 3 includes three adjacent axial partial sections 4a, 4b, 4c in the circumferential direction, adjacent areas 4a, 4b and 4b, 4c having opposite magnetization 7 in the circumferential direction of shaft 3. A measuring coil 5 is assigned to each of the two axially outer axial partial sections 4a, 4c, each of these measuring coils 5 being located at the same vertical level, i.e., distance to axis 2 of shaft 3, as a measuring coil 5 of central axial partial section 4b.

[0033] FIG. 2 shows a system according to one specific example embodiment of the present invention.

[0034] In detail, FIG. 2 essentially shows a system 1 according to FIG. 1, but in contrast to system 1 according to FIG. 1, system 1 according to FIG. 2 includes only two adjacent axial partial sections 4a, 4b, these having opposite magnetization 7a, 7b in the circumferential direction of shaft 3. Assigned to the two axial partial sections 4a, 4b is a 3D magnetic field sensor 5a, 5b, respectively, in the form of a TMR sensor, each of which is arranged in the axial center of particular axial partial section 4a, 4b. The two 3D magnetic field sensors 5a, 5b are also connected to an evaluation unit 6, which is designed for ascertaining, in a conventional way, the torque acting on shaft 3 based on the measured values of the magnetic field of the two sensors 5a, 5b.

[0035] FIG. 3 shows a system according to one specific example embodiment of the present invention.

[0036] In detail, FIG. 3 essentially shows a system 1 according to FIG. 2, but in contrast to system 1 according to FIG. 2, in system 1 according to FIG. 3, the two 3D magnetic field sensors 5a, 5b are arranged as close to each other as possible, i.e., essentially at the shared boundary between the two axial partial sections 4a, 4b. This arrangement corresponds to an arrangement of magnetic field sensors 5a and 5b offset toward the center with respect to partial sections 4a and 4b. Therefore, it is possible to optimize the acting gradient in the profile of the magnetic field between the two measuring sites of external interference fields and the distance outward to possible attachments.

[0037] FIG. 4 shows steps of a method according to one specific example embodiment of the present invention.

[0038] In detail, FIG. 4 shows steps of a method for torque measurement, in particular at a drive of an e-bike. This includes the following steps:

[0039] In a first step S1, at least one axial partial section of at least one shaft, which is rotatable about an axis, is magnetized.

[0040] In one further step S2, the shaft is rotated about its axis.

[0041] In one further step S3, an at least two-dimensional, in particular three-dimensional, measurement is carried out of a change of a magnetic field in the magnetized partial section due to the magnetostrictive effect during the rotation of the shaft about the axis with the aid of at least one TMR sensor.

[0042] In one further step S4, an evaluation is carried out, with the aid of an evaluation unit, of the measured values of the at least one TMR sensor and, in one further step S5, a determination of a torque acting on the shaft is carried out on the basis of the evaluated values.

[0043] In summary, at least one of the specific embodiments of the present invention has at least one of the following advantages: [0044] less installation space [0045] a more precise determination of the torque acting on the shaft [0046] a continuous determination of the torque acting on the shaft [0047] greater flexibility with respect to the arrangement of attachments.

[0048] Although the present invention was described on the basis of preferred exemplary embodiments, it is not limited thereto. Instead, the present invention is modifiable in various ways.