ARRANGEMENT FOR MEASURING A FORCE OR A TORQUE, USING AT LEAST FOUR MAGNETIC SENSORS

Abstract

The present invention relates to an arrangement for measuring a force and/or a torque (Mt) on a machine element extending along an axis, using the inverse magnetostrictive effect. The machine element has a cavity extending along the axis and at least one magnetization region for magnetization purposes, extending circumferentially around the axis in an axial section of the machine element. The arrangement further includes at least one first magnetic field sensor, a second magnetic field sensor, a third magnetic field sensor and a fourth magnetic field sensor, each of which is designed to individually measure an axial direction component of a magnetic field caused by the magnetization and also by the force and/or torque (Mt) and each of which lies in one of the axial sections of the magnetization regions. According to the invention, at least the first magnetic sensor and the second magnetic sensor are arranged in the cavity of the machine element.

Claims

1. An arrangement for measuring at least one of a force or a torque (Mt) on a machine element that extends along an axis comprising a cavity defined in the machine element and extending along the axis and at least one magnetization area extending circumferentially about the axis in an axial section of the machine element for a magnetization; at least one first magnetic field sensor, one second magnetic field sensor, one third magnetic field sensor, and one fourth magnetic field sensor each of which is formed for the individual measurement of an axial directional component of a magnetic field caused by the magnetization and also by at least one of the force or the torque (Mt) and is located in the axial section of the one magnetization area or in one of the axial sections of the multiple magnetization areas; and at least the first magnetic field sensor and the second magnetic field sensor are arranged in the cavity of the machine element.

2. The arrangement according to claim 1, wherein the first magnetic field sensor, the second magnetic field sensor, the third magnetic field sensor, and the fourth magnetic field sensor are arranged in a plane encompassing the axis.

3. The arrangement according to claim 1, wherein the first magnetic field sensor and the second magnetic field sensor are arranged opposite each other with respect to the axis and have an identical distance to the axis.

4. An arrangement according to claim 3, wherein the first magnetic field sensor and the second magnetic field sensor are arranged directly adjacent on both sides of the axis.

5. An arrangement according to claim 3, wherein the third magnetic field sensor and the fourth magnetic field sensor are arranged opposite each other with respect to the axis and have an identical distance to the axis.

6. The arrangement according to claim 5, wherein the third magnetic field sensor and the fourth magnetic field sensor have a greater distance to the axis than the first magnetic field sensor and the second magnetic field sensor.

7. The arrangement according to claim 1, wherein the third magnetic field sensor and the fourth magnetic field sensor are arranged on an inner or outer surface of the machine element, an air gap is formed between the third magnetic field sensor and the inner or outer surface of the machine element, and an air gap is formed between the fourth magnetic field sensor and the inner or outer surface of the machine element.

8. The arrangement according to claim 1, wherein the machine element has two of the magnetization areas extending circumferentially about the axis for magnetization, the first magnetic field sensor and the third magnetic field sensor are arranged at an axial position of the second magnetization area and the second magnetic field sensor and the fourth magnetic field sensor are arranged at an axial position of the first magnetization area.

9. The arrangement according to claim 1, wherein the magnetic field sensors are arranged and wired such that a difference from a sum of axial directional components that are measured with the first magnetic field sensor and with the second magnetic field sensor and a sum of axial directional components that are measured with the third magnetic field sensor and with the fourth magnetic field sensor is determined.

10. The arrangement according to claim 1, wherein the machine element has two of the magnetization areas extending circumferentially about the axis for magnetization and the arrangement further comprises a fifth magnetic field sensor, a sixth magnetic field sensor, a seventh magnetic field sensor , and an eighth magnetic field sensor; the first magnetic field sensor, the second magnetic field sensor, the third magnetic field sensor , and the fourth magnetic field sensor are arranged at an axial position of the first magnetization area; the fifth magnetic field sensor, the sixth magnetic field sensor, the seventh magnetic field sensor, and the eighth magnetic field sensor are arranged at an axial position of the second magnetization area; the fifth magnetic field sensor has an identical radial position and an identical tangential position as the first magnetic field sensor; the sixth magnetic field sensor has an identical radial position and an identical tangential position as the second magnetic field sensor; the seventh magnetic field sensor has an identical radial position and an identical tangential position as the third magnetic field sensor; and the eighth magnetic field sensor has an identical radial position and an identical tangential position as the fourth magnetic field sensor.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Other details, advantages, and refinements of the invention are disclosed from the following description of preferred embodiments of the invention with reference to the drawing. Shown are:

[0054] FIG. 1 a first preferred embodiment of an arrangement according to the invention with four magnetic field sensors,

[0055] FIG. 2 a second preferred embodiment of the arrangement according to the invention with four magnetic field sensors,

[0056] FIG. 3 a third preferred embodiment of the arrangement according to the invention with four magnetic field sensors and two magnetization areas,

[0057] FIG. 4 a fourth preferred embodiment of the arrangement according to the invention with eight magnetic field sensors and two magnetization areas, and

[0058] FIG. 5 a fifth preferred embodiment of the arrangement according to the invention with eight magnetic field sensors and two magnetization areas.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0059] FIG. 1 to FIG. 5 show an arrangement according to the invention each in two views. The left parts of the figures each comprise a cross-sectional view, while the right parts of the figures each comprise a top view of the respective embodiment of the arrangement according to the invention.

[0060] FIG. 1 shows a first preferred embodiment of the arrangement according to the invention. The arrangement comprises first a machine element in the form of a hollow flange 01 that is mounted on a base body 02. A force or a torque, in particular, a torque Mt, acts on the hollow flange 01. The hollow flange 01 has the shape of a hollow circular cylinder. The hollow flange 01 extends along an axis 03 that also forms the center axis of the hollow cylindrical shape of the hollow flange 01. A cylindrical cavity 04 is formed in the interior of the hollow flange 01. The hollow flange 01 is formed of a magneto-elastic material that has the magnetostrictive effect.

[0061] In an axial section of the hollow flange 01 there is a first permanent magnetization area 06 that extends circumferentially about the axis 03, i.e., it is circular permanent magnetization.

[0062] This embodiment of the arrangement according to the invention further comprises a first magnetic field sensor 11, a second magnetic field sensor 12, a third magnetic field sensor 13, and a fourth magnetic field sensor 14. The magnetic field sensors 11, 12, 13, 14 are each formed for the individual measurement of an axial directional component of a magnetic field cause by the magnetization of the permanent magnetization area 06 and by the force and/or by the torque. The magnetic field sensors 11, 12, 13, 14 are arranged in a plane that also comprises the axis 03. The magnetic field sensors 11, 12, 13, 14 have an identical axial position that lies within the axial section of the hollow flange 01 in which the permanent magnetization area 06 is formed. The magnetic field sensors 11, 12, 13, 14 are located in the cavity 04.

[0063] The first magnetic field sensor 11 and the second magnetic field sensor 12 are arranged on an axis 03 and are located directly above and below the axis 03. The first magnetic field sensor 11 and the second magnetic field sensor 12 are arranged, in particular, on a top side and a bottom side of a circuit board (not shown). The first magnetic field sensor 11 and the second magnetic field sensor 12 have a technically minimum distance to the axis 03 that is equal in these two magnetic field sensors 11, 12.

[0064] The third magnetic field sensor 13 and the fourth magnetic field sensor 14 are arranged on the inner surface of the hollow flange 01. The third magnetic field sensor 13 and the fourth magnetic field sensor 14 have an equal distance to the axis 03. The first magnetic field sensor 11 and the second magnetic field sensor 12 are each polarized opposite the third magnetic field sensor 13 and the fourth magnetic field sensor 14.

[0065] FIG. 2 shows a second preferred embodiment of the arrangement according to the invention. This second embodiment differs from the embodiment shown in FIG. 1 only in that the first magnetic field sensor 11 and the second magnetic field sensor 12 are not arranged directly on the axis 03, but instead have a slight distance to the axis 03.

[0066] FIG. 3 shows a third preferred embodiment of the arrangement according to the invention. This third embodiment differs from the embodiment shown in FIG. 1 only in the number of permanent magnetization areas and in the axial arrangement of the magnetic field sensors. In the embodiment shown in FIG. 3, the hollow flange 01 has, next to the first permanent magnetization area 06, a second permanent magnetization area 07 that is located in another axial section of the hollow flange 01 and is arranged axially spaced apart from the first permanent magnetization area 06. For the rest, the first permanent magnetization area 06 and the second permanent magnetization area 07 are identical. In particular, the two permanent magnetization areas 06, 07 have an identical polarity. In contrast to the embodiment shown in FIG. 1, the first magnetic field sensor 11 and the third magnetic field sensor 13 have a deviating axial position, because the first magnetic field sensor 11 and the third magnetic field sensor 13 are arranged at an axial position of the second permanent magnetization area 07.

[0067] FIG. 4 shows a fourth preferred embodiment of the arrangement according to the invention. This fourth embodiment differs from the embodiment shown in FIG. 1 only in the number of permanent magnetization areas and in the number of magnetic field sensors. In the embodiment shown in FIG. 4, the hollow flange 01 has, next to the first permanent magnetization area 06, a second permanent magnetization area 07 that is located in another axial section of the hollow flange 01 and is arranged axially spaced apart from the first permanent magnetization area 06. For the rest, the first permanent magnetization area 06 and the second permanent magnetization area 07 are identical, but the two permanent magnetization areas 06, 07 have different polarities.

[0068] The embodiment shown in FIG. 4 further has a fifth magnetic field sensor 15, a sixth magnetic field sensor 16, a seventh magnetic field sensor 17, and an eighth magnetic field sensor 18 that are identical with respect to their construction and their radial and tangential positions to the first magnetic field sensor 11, the second magnetic field sensor 12, the third magnetic field sensor 13, and the fourth magnetic field sensor 14. However, the fifth magnetic field sensor 15, the sixth magnetic field sensor 16, the seventh magnetic field sensor 17, and the eighth magnetic field sensor 18 have an axial position of the second permanent magnetization area 07.

[0069] Because the two permanent magnetization areas 06, 07 have different polarities, the fifth magnetic field sensor 15 and the sixth magnetic field sensor 16 are each polarized opposite the first magnetic field sensor 11 and the second magnetic field sensor 12. Likewise, the seventh magnetic field sensor 17 and the eighth magnetic field sensor 18 are each polarized opposite the third magnetic field sensor 13 and the fourth magnetic field sensor 14.

[0070] FIG. 5 shows a fifth preferred embodiment of the arrangement according to the invention. This fifth embodiment differs from the embodiment shown in FIG. 4 only in the polarity of the permanent magnetization areas and in the polarization of the magnetic field sensors. In the embodiment shown in FIG. 5, the first permanent magnetization area 06 and the second permanent magnetization area 07 have an identical polarity. For this reason, the fifth magnetic field sensor 15 and the sixth magnetic field sensor 16 are polarized like the first magnetic field sensor 11 and the second magnetic field sensor 12. Likewise, the seventh magnetic field sensor 17 and the eighth magnetic field sensor 18 are polarized like the third magnetic field sensor 13 and the fourth magnetic field sensor 14.

REFERENCE NUMBERS

[0071] 01 Hollow flange [0072] 02 Base body [0073] 03 Axis [0074] 04 Cavity [0075] 05 - [0076] 06 First permanent magnetization area [0077] 07 Second permanent magnetization area [0078] 08 - [0079] 09 - [0080] 11 First magnetic field sensor [0081] 12 Second magnetic field sensor [0082] 13 Third magnetic field sensor [0083] 14 Fourth magnetic field sensor [0084] 15 Fifth magnetic field sensor [0085] 16 Sixth magnetic field sensor [0086] 17 Seventh magnetic field sensor [0087] 18 Eighth magnetic field sensor