Method and arrangement for measuring a force or a moment, using multiple magnetic sensors

Abstract

The present invention relates to a method and an arrangement for measuring a force and/or moment on a machine element extending along an axis, using the inverse magnetostrictive effect. The machine element has a magnetization region for magnetization, this region fully encompassing the axis. The arrangement includes at least one first magnetic sensor and one second magnetic sensor, each being designed to measure individually a first and a second direction component of a magnetic field that is caused by the magnetization and by the force and/or the moment. The direction components that can be measured using the first magnetic sensor have differing orientations. Likewise, the direction components that can be measured using the second magnetic sensor have differing orientations. The first magnetic sensor and the second magnetic sensor are arranged around the axis at different peripheral positions.

Claims

1. An arrangement for measuring at least one of a force or a moment on a machine element extending along an axis, in which the machine element includes a magnetization area for a magnetization extending circumferentially around the axis, the magnetization area is permanently magnetized, so that the magnetization is formed by a permanent magnetization, the arrangement further comprises at least one first magnetic field sensor and one second magnetic field sensor each of which are formed for individually measuring a first and a second directional component of a magnetic field caused by the magnetization and by the at least one of the force or the moment, wherein the first directional component of the magnetic field measurable with the first magnetic field sensor and the second directional component of the magnetic field measurable with the first magnetic field sensor have different orientations, wherein the first directional component of the magnetic field measurable with the second magnetic field sensor and the second directional component of the magnetic field measurable with the second magnetic field sensor have different orientations, and the first magnetic field sensor and the second magnetic field sensor are arranged at different circumferential positions about the axis.

2. The arrangement according to claim 1, wherein the magnetization area has a ring-shaped construction around the axis.

3. The arrangement according to claim 1, wherein the at least two magnetic field sensors each comprise two or three magnetic field sensor elements that are each formed for measuring one of the directional components of the magnetic field caused by the magnetization and by the at least one of the force or the moment.

4. The arrangement according to claim 1, wherein the directional components measurable with the at least two magnetic field sensors are selected from the group: a direction parallel to the axis, a direction radial to the axis, or a direction tangential to the axis.

5. The arrangement according to claim 1, wherein the at least two magnetic field sensors are each further formed for measuring a third directional component of the magnetic field caused by the magnetization and by the at least one of the force or the moment.

6. The arrangement according to claim 1, wherein the at least two magnetic field sensors have an identical distance to the axis.

7. The arrangement according to claim 1, wherein the at least two magnetic field sensors are arranged distributed equally about the axis.

8. The arrangement according to claim 1, wherein the machine element extends in a first section along the axis, so that the axis forms a first axis, the machine element further comprises a second section in which it extends along a second axis arranged perpendicular to the first axis, the second section has a second magnetization area for a second magnetization extending circumferentially about the second axis, the arrangement further comprises at least one additional first magnetic field sensor allocated to the second section and an additional second magnetic field sensor allocated to the second section each of which are constructed for individually measuring at least a first and a second directional component of a magnetic field caused by the second magnetization and by the at least one of the force or the moment, the first directional component measurable with the additional first magnetic field sensor allocated to the second section and the second directional component measurable with the additional first magnetic field sensor allocated to the second section have different orientations, the first directional component measurable with the additional second magnetic field sensor allocated to the second section and the second directional component measurable with the additional second magnetic field sensor allocated to the second section have different orientations, and the additional first magnetic field sensor allocated to the second section and the additional second magnetic field sensor allocated to the second section are arranged at different circumferential positions about the second axis.

9. A method for measuring at least one of a force or a moment, wherein the force or the moment acts on a machine element that extends along an axis and has a magnetization area extending about the axis for a magnetization extending about the axis, the magnetization area is permanently magnetized, so that the magnetization is formed by a permanent magnetization, the method comprising: measuring the at least one of the force or the moment in at least two differential circumferential positions about the axis at each of which at least two directional components with different orientations of a magnetic field caused by the magnetization and by the at least one of the force or the moment are determined.

10. The arrangement according to claim 1, wherein the magnetization area is magnetically neutral outside of the magnetization area in a state of the machine element unloaded by a force or by a moment.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Additional details, advantages, and refinements of the invention are produced from the following description of preferred embodiments of the invention with reference to the drawing. Shown are:

(2) FIG. 1 illustrates a first preferred embodiment of the arrangement according to the invention with four magnetic field sensors;

(3) FIG. 2 illustrates a second preferred embodiment of the arrangement according to the invention with four magnetic field sensors;

(4) FIG. 3 illustrates a third preferred embodiment of the arrangement according to the invention with four magnetic field sensors;

(5) FIG. 4 illustrates a fourth preferred embodiment of the arrangement according to the invention with three magnetic field sensors;

(6) FIG. 5 illustrates a fifth preferred embodiment of the arrangement according to the invention with three magnetic field sensors;

(7) FIG. 6 illustrates a sixth preferred embodiment of the arrangement according to the invention with three magnetic field sensors;

(8) FIG. 7 illustrates a seventh preferred embodiment of the arrangement according to the invention with two magnetic field sensors; and

(9) FIG. 8 illustrates an eighth preferred embodiment of the arrangement according to the invention with four magnetic field sensors;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(10) FIG. 1 to FIG. 7 show the arrangements according to the invention each in two views. The left part of each figure is a cross-sectional view, while the right part of each figure is a top view of the respective embodiment of the arrangement according to the invention.

(11) FIG. 1 shows a first preferred embodiment of the arrangement according to the invention. The arrangement first comprises a machine element in the form of a flange 01 that is mounted on a base body 02. The flange 01 has the shape of a hollow circular cylinder. The flange 01 extends along an axis 03 that also forms the center axis of the hollow cylindrical shape of the flange 01. The flange 01 is formed of a magnetoelastic material that has the magnetostrictive effect.

(12) In an axial section of the flange 01, a permanent magnetization area 04 is formed that extends circumferentially about the axis 03.

(13) Four magnetic field sensors 11, 12, 13, 14 that have an equal distance to the axis 03 and are arranged distributed equally about this axis are arranged circumferentially about the flange 01. The four magnetic field sensors 11, 12, 13, 14 are opposite the permanent magnetization 04. The four magnetic field sensors 11, 12, 13, 14 are each formed by a semiconductor sensor. The four magnetic field sensors 11, 12, 13, 14 are formed to each individually measure three directional components of a magnetic field B. This suitability can alternatively be given such that the magnetic field sensors each comprise three magnetic field sensor elements (not shown) for measuring one of the directional components.

(14) The three Cartesian directions x, y, and z are shown, wherein the axis 03 is in the x direction. Furthermore, for each of the four magnetic field sensors 11, 12, 13, 14, the respective measurable directional components of the magnetic field B are indicated. The indicated directional components have a first suffix, wherein r stands for a radial direction, a for an axial direction, and t for a tangential direction with respect to the axis 03. The indicated directional components have a second suffix that indicates a rotational angle in degrees. The rotational angle is spanned between the position of each of the magnetic field sensors 11, 12, 13, 14 and the z-axis. Because the four magnetic field sensors 11, 12, 13, 14 are arranged distributed equally about the axis 03, the rotational angle =0, 90, 180, or 270.

(15) With the illustrated embodiment of the arrangement according to the invention, the three directional components Mx, My, and Mz of a moment acting on the flange 01 and the directional components Fy and Fz of a force acting on the flange 01 can be measured. The following relationships apply:
M.sub.x=k.sub.1.Math.(B.sub.a0+B.sub.a90+B.sub.a180+B.sub.a270) or M.sub.x=k.sub.2.Math.(B.sub.a0+B.sub.a180) or M.sub.x=k.sub.3.Math.(B.sub.a90+B.sub.a270)
M.sub.y=k.sub.4.Math.(B.sub.t0B.sub.t180) or M.sub.y=k.sub.5.Math.(B.sub.r90B.sub.r270)
M.sub.z=k.sub.6.Math.(B.sub.r0B.sub.r180) or M.sub.z=k.sub.7.Math.(B.sub.t90B.sub.t270)
F.sub.y=k.sub.8.Math.(B.sub.a0B.sub.a180)
F.sub.z=k.sub.9.Math.(B.sub.a90B.sub.a270)
k.sub.1, k.sub.2, k.sub.3, k.sub.4, k.sub.5, k.sub.6, k.sub.7, k.sub.8, k.sub.9: constants

(16) FIG. 2 shows a second preferred embodiment of the arrangement according to the invention. This embodiment is initially equal to the embodiment shown in FIG. 1. Deviating from the embodiment shown in FIG. 1, the four magnetic field sensors 11, 12, 13, 14 are formed to individually measure only two directional components of the magnetic field B, namely in the axial direction and in the tangential direction. This suitability can be alternatively given such that the magnetic field sensors each have two magnetic field sensor elements (not shown) for measuring one of the two directional components.

(17) The following relationships apply:
M.sub.x=k.sub.1.Math.(B.sub.a0+B.sub.a90+B.sub.a180+B.sub.a270) or M.sub.x=k.sub.2.Math.(B.sub.a0+B.sub.a180) or M.sub.x=k.sub.3.Math.(B.sub.a90+B.sub.a270)
M.sub.y=k.sub.4.Math.(B.sub.t0B.sub.t180)
M.sub.z=k.sub.7.Math.(B.sub.t90B.sub.t270)
F.sub.y=k.sub.8.Math.(B.sub.a0B.sub.a180)
F.sub.z=k.sub.9.Math.(B.sub.a90B.sub.a270)
k.sub.1, k.sub.2, k.sub.3, k.sub.4, k.sub.7, k.sub.8, k.sub.9: constants

(18) FIG. 3 shows a third preferred embodiment of the arrangement according to the invention. This embodiment is initially equal to the embodiment shown in FIG. 1. Deviating from the embodiment shown in FIG. 1, the four magnetic field sensors 11, 12, 13, 14 are formed to individually measure only two directional components of the magnetic field B, namely in the axial direction and in the radial direction. This suitability can alternatively be given such that the magnetic field sensors each comprise two magnetic field sensor elements (not shown) for measuring one of the two directional components.

(19) The following relationships apply:
M.sub.x=k.sub.1.Math.(B.sub.a0+B.sub.a90+B.sub.a180+B.sub.a270) or M.sub.x=k.sub.2.Math.(B.sub.a0+B.sub.a180) or M.sub.x=k.sub.3.Math.(B.sub.a90+B.sub.a270)
M.sub.y=k.sub.5.Math.(B.sub.r90B.sub.r270)
M.sub.z=k.sub.6.Math.(B.sub.r0B.sub.r180)
F.sub.y=k.sub.8.Math.(B.sub.a0B.sub.a180)
F.sub.z=k.sub.9.Math.(B.sub.a90B.sub.a270)
k.sub.1, k.sub.2, k.sub.3, k.sub.5, k.sub.6, k.sub.8, k.sub.9: constants

(20) FIG. 4 shows a fourth preferred embodiment of the arrangement according to the invention. This embodiment is initially equal to the embodiment shown in FIG. 1. Deviating from the embodiment shown in FIG. 1, only three of the magnetic field sensors 11, 12, 13 are present. The three magnetic field sensors 11, 12, 13 are distributed equally about the axis 03, so that the rotational angle =0, 120, or 240.

(21) The following relationships apply:
M.sub.x=k.sub.1.Math.(B.sub.a0+B.sub.a120+B.sub.a240)
M.sub.y=k.sub.4.Math.(B.sub.r120B.sub.r240) or M.sub.y=k.sub.5.Math.(B.sub.t0.Math.(B.sub.120+B.sub.t240))
M.sub.z=k.sub.6.Math.(B.sub.t120B.sub.t240) or M.sub.z=k.sub.7.Math.(B.sub.r0.Math.(B.sub.r120+B.sub.r240))
F.sub.y=k.sub.8.Math.(B.sub.a0.Math.(B.sub.a120+B.sub.a240))
F.sub.z=k.sub.9.Math.(B.sub.a120B.sub.a240)
k.sub.1, k.sub.4, k.sub.5, k.sub.6, k.sub.7, k.sub.8, k.sub.9: constants

(22) FIG. 5 shows a fifth preferred embodiment of the arrangement according to the invention. This embodiment is initially equal to the embodiment shown in FIG. 4. Deviating from the embodiment shown in FIG. 4, the three magnetic field sensors 11, 12, 13 are formed to individually measure only two directional components of the magnetic field B, namely in the axial direction and in the tangential direction. This suitability can alternatively be given such that the magnetic field sensors each comprise two magnetic field sensor elements (not shown) for measuring one of the two directional components.

(23) The following relationships apply:
M.sub.x=k.sub.1.Math.(B.sub.a0+B.sub.a120+B.sub.a240)
M.sub.y=k.sub.5.Math.(B.sub.t0.Math.(B.sub.t120+B.sub.t240))
M.sub.z=k.sub.6.Math.(B.sub.t120B.sub.t240)
F.sub.y=k.sub.8.Math.(B.sub.a0.Math.(B.sub.a120+B.sub.a240))
F.sub.z=k.sub.9.Math.(B.sub.a120B.sub.a240)
k.sub.1, k.sub.5, k.sub.6, k.sub.8, k.sub.9: constants

(24) FIG. 6 shows a sixth preferred embodiment of the arrangement according to the invention. This embodiment is initially equal to the embodiment shown in FIG. 4. Deviating from the embodiment shown in FIG. 4, the three magnetic field sensors 11, 12, 13 are formed to individually measure only two directional components of the magnetic field B, namely in the axial direction and in the radial direction. This suitability can alternatively be given such that the magnetic field sensors each comprise two magnetic field sensor elements (not shown) for measuring one of the two directional components.

(25) The following relationships apply:
M.sub.x=k.sub.1.Math.(B.sub.a0+B.sub.a120+B.sub.a240)
M.sub.y=k.sub.4.Math.(B.sub.r120B.sub.r240)
M.sub.z=k.sub.7.Math.(B.sub.r0.Math.(B.sub.a120+B.sub.r240))
F.sub.y=k.sub.8.Math.(B.sub.a0.Math.(B.sub.a120+B.sub.a240))
F.sub.z=k.sub.9.Math.(B.sub.a120B.sub.a240)
k.sub.1, k.sub.4, k.sub.7, k.sub.8, k.sub.9:constants

(26) FIG. 7 shows a seventh preferred embodiment of the arrangement according to the invention. This embodiment is initially equal to the embodiment shown in FIG. 1. Deviating from the embodiment shown in FIG. 1, only two of the magnetic field sensors 12, 14 are present. The two magnetic field sensors 12, 14 are distributed equally about the axis 03, so that the rotational angle =90 or 270.

(27) The following relationships apply:
M.sub.x=k.sub.3.Math.(B.sub.a90+B.sub.a270)
M.sub.y=k.sub.5.Math.(B.sub.r90B.sub.r270)
M.sub.z=k.sub.7.Math.(B.sub.t90B.sub.t270)
F.sub.z=k.sub.9.Math.(B.sub.a90B.sub.a270)
k.sub.3, k.sub.5, k.sub.7, k.sub.9: constants

(28) FIG. 8 shows an eighth preferred embodiment of the arrangement according to the invention. This embodiment is initially equal to the embodiment shown in FIG. 1. Deviating from the embodiment shown in FIG. 1, the flange extends only in a first section 16 along the axis 03, so that the axis 03 forms a first axis 03. In a second section 17, the flange 01 extends along a second axis 18 that is perpendicular to the first axis 03.

(29) The flange 01 has, in its second section 17, a second permanent magnetization area 19, so that the permanent magnetization area 04 in the first section 16 forms a first permanent magnetization area. The two magnetic field sensors 12, 14 are allocated to the first permanent magnetization area 04. In the same way, a first magnetic field sensor 21 and a second magnetic field sensor 22 are allocated to the second permanent magnetization area 19.

(30) With the four magnetic field sensors 12, 14, 21, 22, all three directional components Mx, My, and Mz of the moment acting on the flange 01 and all three directional components Fx, Fy, and Fz of the force acting on the flange 01 can be measured. Here, alternatively another of the magnetic field sensor arrangements shown in FIG. 1 to FIG. 7 can also be selected for the two sections 16, 17 of the flange 01. A prerequisite for this is that the force causing the load or the moment causing the load is applied in the second section 17 of the flange 01.

LIST OF REFERENCE NUMBERS

(31) 01 Flange 02 Base body 03 Axis 04 Permanent magnetization area 05 - 06 - 07 - 08 - 09 - 10 - 11 First magnetic field sensor 12 Second magnetic field sensor 13 Third magnetic field sensor 14 Fourth magnetic field sensor 15 - 16 First section 17 Second section 18 Second axis 19 Second permanent magnetization area 20 - 21 First magnetic field sensor allocated to the second section 22 Second magnetic field sensor allocated to the second section