Redundant torque sensor—multiple band arrays

Abstract

A device for determining an external magnetic influence has a component comprising ferromagnetic material and a magnetizable region comprising at least three opposing magnetic tracks. The at least three magnetic opposing magnetic tracks are magnetizable in opposite directions, form at least two groups, and are arranged axially relative to the component. A first magnetic field sensor for emitting a signal is arranged radially to the component and assigned to the first group. A second magnetic field sensor for emitting a signal is arranged radially to the component and assigned to the second group. Redundant magnetic field sensors, each configured for emitting a signal, may be arranged radially in relation to the component for each of the first and second groups. The signals of the first and the second sensors can be set in relation to each other and in relation to the signals of the redundant first and second sensors.

Claims

1. A device for determining an external magnetic influence comprising: a component comprised of a ferromagnetic material and having a center axis, the component having a magnetizable region comprising at least three magnetic tracks with adjacent magnetic tracks being magnetized in opposite directions of each other, the at least three magnetic tracks being arranged circumferentially and perpendicular to the component center axis; at least two coils of a first magnetic field sensor for emitting a signal, the first magnetic field sensor coils being arranged axially in relation to the component and radially spaced from the component, and being assignable to the first outer and at least one middle magnetic track, respectively; at least two coils of a second magnetic field sensor for emitting a signal, the second magnetic field sensor coils being arranged axially in relation to the component and radially spaced from the component, and being assignable to the at least one middle and second outer magnetic track, respectively; and wherein the signal of the first sensor is configured to be set in relation to the signal of the second sensor.

2. A device according to claim 1, characterised in that one of the two sensors is configured in the form of a redundant sensor.

3. A device according to claim 1, characterised in that the component is a shaft.

4. A device according claim 1 further comprising at least two further coils arranged axially in relation to the component and radially spaced from the component, and being assignable to the first and middle magnetic track, respectively, and at least two further coils arranged axially in relation to the component and radially spaced from the component, and being assignable to the middle and third magnetic track, respectively.

5. A device according to claim 1, characterised in that at least one of the first and second magnetic field sensor are arranged in relation to the component in a non-contacting manner.

6. A device according to claim 1, characterised in that at least one of the first and second magnetic field sensor comprise a fluxgate.

7. A device according to claim 1, characterised in that the component is configured to be subject to a torque about its center axis.

8. A device according to claim 1, characterised in that the diameter of the component in a region adjacent to the at least first sensor differs from the diameter of the component in a region adjacent to the further sensor.

9. A method for determining an external magnetic influence comprising: providing a component comprised of a ferromagnetic material and having a center axis; magnetizing the component in a manner to generate at least three opposing magnetic tracks of a magnetizable region wherein the adjacent magnetic tracks are magnetizable in opposite directions from each other, and at least two groups of adjacent magnetic tracks are arranged in an overlapping manner and axially displaced on the component relative to the center axis; arranging a first magnetic field sensor radially spaced from the component in a manner such that the first magnetic field sensor is assigned to the first and middle magnetic track, respectively, wherein the first magnetic field sensor is configured for emitting a signal; arranging a second magnetic field sensor radially spaced from the component in a manner such that the second magnetic field sensor is assigned to the middle and third magnetic track, wherein the second magnetic field sensor is configured for emitting a signal; and setting of the signal of the first sensor in relation to the signal of the second sensor.

10. A device for determining an external magnetic influence, comprising: a component having a center axis and comprising a ferromagnetic material, the component having a magnetizable region comprising at least three opposing magnetic tracks, wherein the adjacent magnetic tracks are magnetizable in opposite directions from each other, and at least two groups of adjacent magnetic tracks are arranged in an overlapping manner and axially displaced on the component; a first magnetic field sensor having at least two coils for emitting a signal, the first magnetic field sensor coils being arranged axially in relation to the component and being radially spaced from the component, the first magnetic field sensor coils being assignable to the first and middle magnetic track; a second magnetic field sensor with at least two coils for emitting a signal, the second magnetic field sensor coils being arranged axially in relation to the component and being radially spaced from the component, the second magnetic field sensor coils being assignable to the middle and third magnetic track; and wherein the signal of the first sensor is configured to be set in relation to the signal of the second sensor.

Description

(1) Further aspects and features of the invention result from the following description of preferred embodiments of the invention according to FIGS. 1 to 3.

(2) FIG. 1 shows a schematic view of a component, in particular a shaft, having three magnetic tracks surrounding the shaft,

(3) FIG. 2 shows the cross section of the component, in particular the shaft, with magnetic field sensors arranged on the respective upper side and bottom side of the shaft,

(4) FIG. 3 shows a view comparable to FIG. 1, with the difference that four magnetic tracks are provided,

(5) FIG. 4 shows a coordinate system with a first curve assigned to a first sensor and a second curve assigned to a second sensor,

(6) FIG. 5 shows a coordinate system with a curve assigned to a first sensor and a second curve assigned to a second sensor, with an external magnetic field acting on the curves, and

(7) FIG. 6 shows a component with the arrangement of magnetic fields in regions of different diameters.

(8) FIG. 1 shows a component 1 with a magnetised region 2. The magnetised region 2 comprises three magnetic tracks 3, 4, 5. The magnetic tracks 3, 4, 5 adjacent to each other each have an opposing circumferential magnetisation 8, 9. The magnetic track 3 and the magnetic track 5 have a circumferential magnetisation 9. The common magnetic track 4 has a magnetisation 8 opposing 9.

(9) The magnetised region 2 is subdivided into two groups 6, 7.

(10) The magnetic tracks 3 and 4 are assigned to the first group 6 of the magnetised region 2.

(11) The magnetic tracks 4 and 5 are assigned to the second group 7 of the magnetised region 2. Both groups 6, 7 of the magnetic tracks 3, 4, 5 have the magnetic track 4 in common.

(12) A first sensor 10 is assigned to the magnetic tracks 3 and 4. The first sensor 10 comprises the coils 11, 12 as well as the coils 13, 14 if there should be the possibility to detect a movement of the component 1 in the radial direction. In this way, the distance change is compensated. In other words, the integral of the distances of the coils from the surface of the component, in particular the surface of the shaft, is kept constant.

(13) The second sensor 15 of the second group 7 comprises at least the coils 16, 17, whereas the coils 18, 19 are required for compensating radial movements and serve the purpose of correcting rotation-dependent errors.

(14) The sensors 10 and 15 are arranged in such a manner that the component 1, preferably the shaft, extends between the coils 11 and 13, 12 and 14, 16 and 18, 17 and 19, respectively.

(15) The arrangement of the component 1 between the coils 11, 12, 16, 17 and the coils 13, 14, 18, 19 allows the component 1 to move away from the coils 11, 12, 16, 17 and, at the same time, to approach the coils 13, 14, 18, 19, and vice versa, when performing a radial movement 20 between the coils 11, 12, 16, 17 and 13, 14, 18, 19.

(16) Independent of the radial movement 20 of the component 1, the magnetic tracks 3, 4, 5 thus always remain within the effective range of either the coils 11, 12, 16, 17 or the coils 13, 14, 18, 19 of the associated sensors 10 and 15, respectively. Hence, the functional capability of the sensors 10 and 15 is maintained independent of the radial movement 20 of the component 1 within the coils 11, 12, 16, 17 and 13, 14, 18, 19.

(17) Since the magnetic track 4 is assigned both to the first group of magnetic tracks 6 and the second group of magnetic tracks 7, the two coils 12 and 14 of the first sensor 10 and the two coils 16 and 18 of the sensor 15 are assigned to the magnetic track 4.

(18) FIG. 1 shows a view in which the coils 12, 16 on the one hand and the coils 14, 18 on the other are arranged vertically, that is to say above and below each other. In the axial direction, these middle coils are located in exactly the same place, but they are arranged in a rotatory manner according to the installation space required. The distance from the component, in particular from the surface of the shaft, is identical.

(19) In FIG. 1, the sensor 15 has the function of redundant sensor.

(20) FIG. 2 shows a cross section of the component 1 with the sensor 10 including its coils 11 and 12 arranged at the top as well as the second sensor 15 including the coils 16, 17, which is likewise arranged at the top.

(21) The second sensor 15 with separate coils 18 and 19 can be arranged offset relative to the component 1 on the bottom side thereof. Opposite the second sensor 15, the first sensor 10 with the coils 13 and 14 is shown, which is likewise arranged on the bottom side of the component 1.

(22) In FIG. 2, the constructional displacement of the sensors is shown in such a way that the coils 11, 12 of the first sensor 10 on the upper side of the component 1 are arranged diagonally opposite the coils 13 and 14 of the first sensor 10 on the bottom side of the component 1.

(23) On the upper side of the component 1, the coils 16, 17 of the second sensor 15 are arranged in the same manner at an angle of 180 degrees opposite the coils 18, 19 of the second sensor 15 on the bottom side of the component.

(24) FIG. 3 show a component 1, in particular a shaft, with a magnetised region 2 comprising magnetic tracks 21, 22, 23, 24. Thus, the so-called quad-band magnetisation 59 shown in FIG. 3 has a first outer magnetic track 21, two middle magnetic tracks 22, 23 as well as a second outer magnetic track 24.

(25) The magnetic tracks 21, 22, 23, 24 arranged adjacent to each other have an opposing circumferential magnetisation 8, 9.

(26) The magnetised region 2 of the component 1 is subdivided into a group 25 of magnetic tracks 21, 22, 23 and a group 26 of magnetic tracks 22, 23, 24.

(27) The magnetic tracks 22 and 23 are common magnetic tracks of the group 25 and the group 26. In the arrangement of the two groups 25 and 26 on the component 1, the common magnetic tracks 22 and 23 of the group 25 overlap the group 26, and vice versa.

(28) In FIG. 3, a sensor 27 is assigned to the first group 25 of the magnetic tracks 21, 22, 23.

(29) A sensor 29 is assigned to the second group 26 of the magnetic tracks 22, 23, 24 in FIG. 3.

(30) The sensor 27 of the first group 25 comprises the coils 31, 32, 33, 34, 35, 36, 37, 38. The coils 33, 34, 37, 38 serve the purpose of detecting radial movements and a so-called rotational signal uniformity.

(31) The sensor 29 of the second group 26 of the magnetic tracks 22, 23, 24 comprises the coils 39, 40, 41, 42, 43, 44, 45, 46. The coils 41, 42, 45, 46 serve the purpose of detecting radial movements and a so-called rotational signal uniformity.

(32) Here, the coils 39, 40, 43 and 44 are arranged relative to the component 1 on the upper side thereof and the coils 41, 42, 45 and 46 on the opposite bottom side.

(33) In the event that the component 1, preferably a shaft, moves in the radial direction 20 between the coils 31, 32, 35, 39, 36, 40, 43, 44 on the one hand and the coils 33, 34, 37, 41, 38, 42, 45, 46 on the other, with increasing distance from the coils 31, 32, 35, 36, 39, 40, 43, 44, the magnetic tracks 21, 22, 23, 24 reach the effective range of the coils 33, 34, 37, 38, 41, 42, 45, 46, and vice versa.

(34) FIG. 4 shows a quadrant of a Cartesian coordinate system with an x-axis on which the torque values are plotted in Nm.

(35) On the corresponding y-axis, however, voltage values are plotted in volt (V).

(36) A curve 48 and a curve 49 are plotted in the coordinate system.

(37) Both curves 48, 49 relate to a magnetic field 2 of a component 1 with three magnetic tracks 3,4,5 corresponding to the illustration in FIG. 1.

(38) The curve 48 is assigned to the sensor 10, 27 and the curve 49 to the sensor 15, 29.

(39) Both curves 48 and 49 have their starting points at 0 Nm on the x-axis and at a value V indicated by reference numeral 50 on the y-axis.

(40) As a result of the magnetisation 9, 8 of the magnetic tracks 3, 4 of the first group 6, with increasing Nm values on the x-axis, the curve 48 shows increasing V values on the y-axis.

(41) Due to the reversal of magnetisation 8, 9 of the magnetic tracks 4, 5 of the second group 7 of the magnetised region 2, with increasing Nm values on the x-axis of the coordinate system, the curve 49 shows decreasing V values on the y-axis.

(42) FIG. 5 shows a Cartesian coordinate system with a first quadrant 51 and a second quadrant 52.

(43) In accordance with FIG. 4, a curve 48 assigned to the sensor 10 and a curve 49 assigned to the sensor 15 are plotted in FIG. 5.

(44) Contrary to the illustration in FIG. 4, the two curves 48 and 49 each have their starting points at 0 Nm on the x-axis and at 0 V on the y-axis.

(45) The further course of the curves 48 and 49 corresponds to the respective description of both curves in FIG. 4.

(46) Due to an external magnetic field, the magnetisation 8, 9 of the magnetic tracks 3, 4, 5 is influenced in such a way that a unidirectional parallel shift of the curves 48 and 49 takes place.

(47) Due to the parallel shift, a curve 53 is assigned to the curve 48, and a parallel curve 54 is assigned to the curve 49.

(48) In addition, it can be seen from FIG. 5 that the parallel shifts of the curve 48 of the sensor 10 and the curve 49 of the sensor 15 take place to a different extent.

(49) The curve 48 of the sensor 10 is shifted by a distance 55, whereas the curve 49 of the sensor 15 is shifted parallel by a smaller distance 56, which means that the two sensors are exposed to different external magnetic influences.

(50) FIG. 6 shows a component 1 having a region 57 with a smaller diameter and a region 58 with a larger diameter. A magnetised region 2 with a quad-band magnetisation 59 is shown in the region 57. In the region 58, however, a magnetised region 2 is shown which comprises two magnetic tracks 3, 5. The adjacent magnetic tracks have magnetisations 8 and 9 opposing each other.

REFERENCE NUMERALS

(51) 1 component 2 magnetised region 3 magnetic track 4 common magnetic track 5 magnetic track 6 group 7 group 8 magnetisation 9 magnetisation 10 first sensor; first group 11 coil 12 coil 13 coil 14 coil 15 second sensor; second group 16 coil 17 coil 18 coil 19 coil 20 radial movement 21 magnetic track 22 magnetic track 23 magnetic track 24 magnetic track 25 group 26 group 27 sensor; first group 28 left blank 29 sensor; second group 30 left blank 31 coil 32 coil 33 coil 34 coil 35 coil 36 coil 37 coil 38 coil 39 coil 40 coil 41 coil 42 coil 43 coil 44 coil 45 coil 46 coil 47 value at 0 Nm 48 curve; sensor 10 49 curve; sensor 15 50 V value; y-axis 51 first quadrant 52 second quadrant 53 parallel curve; sensor 10 54 parallel curve; sensor 15 55 distance; curve sensor 10 56 distance; curve sensor 15 57 region 58 region 59 quad-band magnetisation