JP2019190997A - Magnetic field detector - Google Patents

Abstract

To improve detection accuracy of a magnetic field generated in association with rotation of a rotational member.SOLUTION: A magnet 2 is connected to a steering shaft 100. A first yoke 31 and a second yoke 32 are arranged in a direction along the axis A of rotation of the steering shaft 100. A detection unit 4 detects a magnetic field and outputs a signal according to the detected magnetic field. A first base part 31a of the first yoke 31 and a second base part 32a of the second yoke 32 have portions extending in a direction of the rotation of the steering shaft 100. A plurality of first teeth parts 31b of the first yoke 31 protrude from the first base part 31a along an axis A of rotation and faces a magnet 2 in a direction perpendicular to the axis A of the rotation. A plurality of second teeth parts 32b of the second yoke 32 protrude from the second base part 32a along the axis A of the rotation and faces the magnet 2 in a direction perpendicular to the axis A of the rotation. The detection unit 4 is arranged between the first base part 31a and the second base part 32a in the direction along the axis A of the rotation. The plurality of second teeth parts 32b protrude to an opposite direction to a direction of the first teeth parts 31b, which is a direction away from the first base part 31a.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a magnetic field detection device that detects a magnetic field generated with rotation of a rotating member.

  As an example of this type of magnetic field detection device, Patent Document 1 discloses a torque detection device. The torque detection device detects torque applied to a steering shaft mounted on a vehicle as an example of a rotating member. The steering shaft includes an input shaft portion and an output shaft portion connected by a torsion bar. The torsion bar is an elastic member capable of twisting deformation. The input shaft portion is connected to a steering member such as a steering wheel. The output shaft portion is connected to the gear mechanism of the power steering mechanism.

  Depending on the steering force input to the input shaft, steering torque is generated on the steering shaft. As a result, the torsion bar is torsionally deformed, and a relative displacement along the circumferential direction of the steering shaft occurs between the input shaft portion and the output shaft portion.

  The torque detection device includes a magnet, a first yoke, and a second yoke. The magnet is coupled to the input shaft portion, and the first yoke and the second yoke are coupled to the output shaft portion. The first yoke and the second yoke are arranged in a direction along the rotation axis of the steering shaft.

  The first yoke includes a first base portion and a plurality of first tooth portions. The first base portion extends along the rotation direction of the steering shaft. The plurality of first teeth protrudes from the first base along the rotation axis of the steering shaft, and faces the magnet in a direction crossing the rotation axis of the steering shaft. The second yoke includes a second base portion and a plurality of second tooth portions. The second base portion extends along the rotation direction of the steering shaft. The plurality of second teeth protrudes from the second base along the rotation axis of the steering shaft, and faces the magnet in a direction intersecting with the rotation axis of the steering shaft.

  When no relative displacement occurs between the input shaft portion and the output shaft portion, no magnetic flux leaks outside the first yoke and the second yoke. On the other hand, when a relative displacement occurs between the input shaft portion and the output shaft portion, the magnetic flux leaks outside the first yoke and the second yoke. The torque detection device detects torque generated in the steering shaft by detecting the magnetic flux.

JP, 2006-206091, A

  An object of the present invention is to improve the detection accuracy of a magnetic field generated as the rotating member rotates.

One aspect for achieving the above object is a magnetic field detection device,
A magnetic field source coupled to the rotating member;
A magnetic yoke member including a first yoke and a second yoke arranged in a direction along the rotation axis of the rotating member;
A detection unit that detects a magnetic field and outputs a signal corresponding to the detected magnetic field;
With
The first yoke is
A first base having a portion extending along the direction of rotation of the rotating member;
A plurality of first teeth protruding from the first base along the rotation axis and facing the magnetic field generation source in a direction intersecting the rotation axis;
With
The second yoke is
A second base having a portion extending along the rotational direction;
A plurality of second teeth protruding from the second base along the rotation axis and facing the magnetic field generation source in a direction intersecting the rotation axis;
With
The detector is disposed between the first base and the second base in the direction along the rotation axis,
The plurality of second teeth protrudes in a direction opposite to the plurality of first teeth and away from the first base.

One aspect for achieving the above object is a magnetic field detection device,
A magnetic field source coupled to the rotating member;
A magnetic yoke member including a first yoke, a second yoke, and a third yoke arranged in a direction along the rotation axis of the rotating member;
A detection unit that detects a magnetic field and outputs a signal corresponding to the detected magnetic field;
With
The first yoke is
A first base having a portion extending along the direction of rotation of the rotating member;
A plurality of first teeth protruding from the first base along the rotation axis and facing the magnetic field generation source in a direction intersecting the rotation axis;
With
The second yoke is
A second base having a portion extending along the rotational direction;
A plurality of second teeth protruding from the second base along the rotation axis and facing the magnetic field generation source in a direction intersecting the rotation axis;
With
The third yoke is
A third base having a portion extending along the rotational direction;
A plurality of second teeth protruding from the third base along the rotation axis at the same position along the rotation direction as the plurality of second teeth and facing the magnetic field generation source in a direction intersecting the rotation axis. Three teeth,
With
The detector is disposed between the first base and the second base in the direction along the rotation axis,
The plurality of second teeth protrudes in the same direction as the plurality of first teeth and in a direction approaching the first base,
The length of the plurality of second tooth portions in the direction along the rotation axis is shorter than the length of the plurality of first tooth portions in the same direction,
The plurality of third teeth protrudes in a direction opposite to the plurality of second teeth and away from the second base.

One aspect for achieving the above object is a magnetic field detection device,
A magnetic field source coupled to the rotating member;
A magnetic yoke member including a first yoke, a second yoke, a third yoke, and a fourth yoke arranged in a direction along the rotation axis of the rotating member;
A detection unit that detects a magnetic field and outputs a signal corresponding to the detected magnetic field;
With
The first yoke is
A first base having a portion extending along the direction of rotation of the rotating member;
A plurality of first teeth protruding from the first base along the rotation axis and facing the magnetic field generation source in a direction intersecting the rotation axis;
With
The second yoke is
A second base having a portion extending along the rotational direction;
The plurality of first teeth projecting from the second base along the rotation axis at different positions along the rotation direction with the plurality of first teeth and facing the magnetic field generation source in a direction intersecting the rotation axis. Two teeth,
With
The third yoke is
A third base having a portion extending along the rotational direction;
A plurality of first teeth protruding from the third base along the rotation axis at the same position along the rotation direction as the plurality of first teeth and facing the magnetic field generation source in a direction intersecting the rotation axis. Three teeth,
With
The fourth yoke is
A fourth base having a portion extending along the rotational direction;
A plurality of second teeth protruding from the fourth base along the rotation axis at the same position along the rotation direction as the plurality of second teeth and facing the magnetic field generation source in a direction intersecting the rotation axis. Four teeth,
With
The detector is disposed between the first base and the second base in the direction along the rotation axis,
The plurality of second tooth portions project in a direction opposite to the plurality of first tooth portions and in a direction approaching the first base portion,
The plurality of third tooth portions project in a direction opposite to the plurality of first tooth portions and away from the first base portion,
The plurality of fourth teeth protrudes in a direction opposite to the plurality of second teeth and away from the second base.

  When a detection unit for detecting a magnetic field is disposed between the first base of the first yoke and the second base of the second yoke, two methods can be considered in order to improve the detection accuracy of the magnetic field. First, what is necessary is just to narrow the space | interval of a 1st base and a 2nd base. Second, it is only necessary to increase the area of receiving the magnetic flux by increasing the length of each first tooth portion and each second tooth portion.

  However, in the case of the configuration shown in Patent Document 1, the first method and the second method are incompatible with each other. Specifically, the plurality of second tooth portions in the second yoke protrude in a direction opposite to the plurality of first tooth portions in the first yoke and in a direction approaching the first base portion. That is, if the distance between the first base portion and the second base portion is narrowed, the length dimension of each first tooth portion and each second tooth portion cannot be increased. On the other hand, if the protruding length dimension of each first tooth portion and each second tooth portion is increased, the interval between the first base portion and the second base portion cannot be reduced.

  According to the configuration of each aspect described above, the length dimension of each first tooth portion and each second tooth portion can be increased while narrowing the distance between the first base portion and the second base portion. Therefore, the detection accuracy of the magnetic field by the detection unit is improved.

  When the rotating member includes a first rotating member and a second rotating member that are coupled so as to be relatively rotatable, in the magnetic field detection device according to each aspect, the magnetic field generation source is coupled to the first rotating member. And the said detection part can detect the torque added to the said rotation member based on the said magnetic field by couple | bonding the said magnetic yoke member with the said 2nd rotation member.

  According to the present invention, the detection accuracy of the magnetic field generated with the rotation of the rotating member is improved.

The structure of the torque detection apparatus which concerns on 1st embodiment is shown typically. The external appearance of the 1st yoke and the 2nd yoke in the torque detection apparatus of FIG. 1 is shown. It is a figure explaining the advantage of the torque detection apparatus of FIG. The structure of the torque detection apparatus which concerns on 2nd embodiment is shown typically. The external appearance of the 1st yoke in the torque detection apparatus of Drawing 4, the 2nd yoke, and the 3rd yoke is shown. It is a figure explaining the advantage of the torque detection apparatus of FIG. The structure of the torque detection apparatus which concerns on 3rd embodiment is shown typically. The external appearance of the 1st yoke in the torque detection apparatus of Drawing 7, the 2nd yoke, the 3rd yoke, and the 4th yoke is shown. It is a figure explaining the advantage of the torque detection apparatus of FIG.

  Exemplary embodiments will be described in detail below with reference to the accompanying drawings. In each drawing used in the following description, the scale is appropriately changed to make each member a recognizable size. In the accompanying drawings, the arrow U indicates the upward direction of the illustrated structure. Arrow D indicates the downward direction of the illustrated structure. The expressions “upper” and “lower” appearing in the following description are merely used for convenience of description, and are not intended to limit the posture when the illustrated structure is used.

  FIG. 1 schematically shows the configuration of a torque detection device 1A according to the first embodiment. The torque detection device 1A is an example of a magnetic field detection device.

  The torque detection device 1A is attached to a steering shaft 100 in a power steering device of a vehicle, for example. The steering shaft 100 is an example of a rotating member that can rotate around the rotation axis A.

  The steering shaft 100 includes an input shaft portion 101, an output shaft portion 102, and a torsion bar 103. The input shaft portion 101 and the output shaft portion 102 are connected via a torsion bar 103. The torsion bar 103 is an elastic member capable of twisting deformation. The input shaft portion 101 is connected to a steering member such as a steering wheel. The output shaft portion 102 is connected to a gear mechanism of the power steering device. The input shaft portion 101 is an example of a first rotating member. The output shaft portion 102 is an example of a second rotating member.

  The torque detection device 1 </ b> A includes a magnet 2. The magnet 2 has a ring shape. In the magnet 2, N and S poles are alternately magnetized in the circumferential direction of the ring shape. The magnet 2 is coupled to the input shaft portion 101 of the steering shaft 100. Specifically, the magnet 2 is coupled so that the N pole and the S pole appear alternately in the rotation direction of the steering shaft 100. The magnet 2 is an example of a magnetic field generation source. The magnet 2 can be replaced with an appropriate member as long as it is a magnetic body that exhibits ferromagnetism or ferrimagnetism by magnetization.

  The torque detection device 1 </ b> A includes a magnetic yoke member 3. The magnetic yoke member 3 includes a spacer 30, a first yoke 31, and a second yoke 32. Each of the first yoke 31 and the second yoke 32 includes a soft magnetic material. The spacer 30 includes a nonmagnetic material.

  As shown in FIG. 2A, the first yoke 31 includes a first base portion 31a and a plurality of first tooth portions 31b. The first base portion 31a has a ring shape. The plurality of first tooth portions 31b protrude upward from the first base portion 31a. The plurality of first tooth portions 31b are arranged at equal intervals along the circumferential direction of the first base portion 31a.

  As shown in FIG. 2B, the second yoke 32 includes a second base portion 32a and a plurality of second tooth portions 32b. The second base portion 32a has a ring shape. The plurality of second tooth portions 32b protrude downward from the second base portion 32a. The plurality of second tooth portions 32b are arranged at equal intervals along the circumferential direction of the second base portion 32a.

  As shown in FIG. 1, the magnetic yoke member 3 has a ring shape as a whole. The magnetic yoke member 3 is attached to the output shaft portion 102 of the steering shaft 100. The magnetic yoke member 3 is disposed concentrically with the magnet 2.

  The first base portion 31 a of the first yoke 31 has a portion extending along the rotation direction of the steering shaft 100. The plurality of first tooth portions 31 b are opposed to the magnet 2 in the radial direction of the steering shaft 100 while protruding from the first base portion 31 a in the direction along the rotation axis A of the steering shaft 100. The radial direction of the steering shaft 100 is an example of a direction that intersects the rotation axis A.

  The second base portion 32 a of the second yoke 32 has a portion extending along the rotation direction of the steering shaft 100. The plurality of second tooth portions 32 b are opposed to the magnet 2 in the radial direction of the steering shaft 100 while protruding from the second base portion 32 a in the direction along the rotation axis A of the steering shaft 100. The length of each second tooth portion 32 b in the second yoke 32 matches the length of each first tooth portion 31 b in the first yoke 31.

  The magnetic yoke member 3 is integrally formed by the spacer 30 so that the first yoke 31 and the second yoke 32 are separated in a direction along the rotation axis A of the steering shaft 100. That is, the first yoke 31 and the second yoke 32 are arranged in a direction along the rotation axis A.

  When a steering force is input to the input shaft portion 101 through the steering member, the entire steering shaft 100 rotates. The magnet 2 and the magnetic yoke member 3 also rotate with the steering shaft 100.

  Depending on the steering force input to the input shaft portion 101, a steering torque is generated in the steering shaft 100. As a result, the torsion bar 103 is torsionally deformed, and a relative displacement along the circumferential direction of the steering shaft 100 occurs between the input shaft portion 101 and the output shaft portion 102.

  Although not shown, the central portion of each first tooth portion 31 b in the circumferential direction of the first yoke 31 is located on the magnetization boundary line of the magnet 2 when viewed from the radial direction of the steering shaft 100. Similarly, the central portion of each second tooth portion 32 b in the circumferential direction of the second yoke 32 is located on the magnetization boundary line of the magnet 2 when viewed from the radial direction of the steering shaft 100.

  In this case, the same number of lines of magnetic force enter and exit the first tooth portion 31b and the second tooth portion 32b from the north and south poles of the magnet 2. Since the magnetic lines of force form a closed loop inside each of the first yoke 31 and the second yoke 32, no magnetic flux leaks outside the magnetic yoke member 3.

  When steering torque is generated in the steering shaft 100 and the torsion bar 103 is torsionally deformed, the relative position between the magnet 2 and the magnetic yoke member 3 changes in the circumferential direction of the steering shaft 100. Thereby, the position of each 1st tooth part 31b and each 2nd tooth part 32b shift | deviates to the said circumferential direction from said magnetization boundary line.

  In this case, lines of magnetic force having opposite polarities in the first yoke 31 and the second yoke 32 are increased. As a result, a magnetic flux is generated between both yokes. That is, the magnetic flux changes according to the torque generated in the steering shaft 100.

  The torque detection device 1 </ b> A includes a detection unit 4. The detection unit 4 is configured to detect a magnetic field and output a signal corresponding to the detected magnetic field. The detection unit 4 includes a magnetic detection element such as a Hall element or a magnetoresistive element. The detector 4 is disposed between the first base 31 a of the first yoke 31 and the second base 32 a of the second yoke 32 in the direction along the rotation axis A of the steering shaft 100. Specifically, the detection unit 4 is configured to detect a magnetic flux generated between the first base portion 31a and the second base portion 32a and output a detection signal corresponding to the density of the magnetic flux. The detection signal is sent to a control device such as an ECU for signal processing.

  In the present embodiment, the plurality of second tooth portions 32b in the second yoke 32 protrude in the direction opposite to the plurality of first tooth portions 31b in the first yoke 31 and away from the first base portion 31a. The advantage of such a configuration will be described with reference to FIG.

  FIG. 3A schematically shows a configuration of a first yoke 91 and a second yoke 92 as a comparative example. The first yoke 91 includes a first base portion 91a and a plurality of first tooth portions 91b. The second yoke 92 includes a second base portion 92a and a plurality of second tooth portions 92b. The plurality of second tooth portions 92b in the second yoke 92 protrude in a direction opposite to the plurality of first tooth portions 91b in the first yoke 91 and in a direction approaching the first base portion 91a. The first yoke and the second yoke provided in the torque detection device described in Patent Document 1 described above have such a configuration.

  When a detection unit for detecting a magnetic field is disposed between the first base 91a of the first yoke 91 and the second base 92a of the second yoke 92, there are two methods for improving the magnetic field detection accuracy. Conceivable. First, the distance G9 between the first base portion 91a and the second base portion 92a may be narrowed. Second, it is only necessary to increase the length L9 of each first tooth portion 91b and each second tooth portion 92b to increase the area for receiving magnetic flux.

  However, in the case of the configuration shown in FIG. 3A, the first method and the second method are incompatible with each other. That is, if the gap G9 between the first base portion 91a and the second base portion 92a is narrowed, the length dimension L9 of each first tooth portion 91b and each second tooth portion 92b cannot be increased. On the other hand, if the protruding length L9 of each first tooth portion 91b and each second tooth portion 92b is increased, the gap G9 between the first base portion 91a and the second base portion 92a cannot be reduced.

  FIG. 3B schematically shows the configuration of the first yoke 31 and the second yoke 32 according to this embodiment. As described above, the plurality of second tooth portions 32b in the second yoke 32 protrude in the direction opposite to the plurality of first tooth portions 31b in the first yoke 31 and away from the first base portion 31a.

  As is apparent from the comparison between the two figures, according to the configuration of the present embodiment, the distance G3 between the first base portion 31a and the second base portion 32a is narrowed while the first tooth portions 31b and the second tooth portions 32b The length dimension L3 can be increased. Therefore, the detection accuracy of the magnetic field by the detection unit 4 is improved.

  In the present embodiment, the first yoke 31 is a single member having an annular first base portion 31a. However, the first yoke 31 may be configured by a plurality of members having an arc-shaped first base portion that extends along the rotation direction of the steering shaft 100.

  Similarly, the second yoke 32 is a single member having an annular second base portion 32a. However, the second yoke 32 can be constituted by a plurality of members having an arc-shaped second base portion extending along the rotation direction of the steering shaft 100.

  FIG. 4 schematically shows the configuration of the torque detection device 1B according to the second embodiment. The torque detection device 1B is an example of a magnetic field detection device. Constituent elements having substantially the same configurations and functions as those described with reference to the torque detection device 1A according to the first embodiment are given the same reference numerals, and repeated descriptions are omitted.

  The torque detection device 1 </ b> B includes a magnetic yoke member 5. The magnetic yoke member 5 includes a spacer 50, a first yoke 51, a second yoke 52, and a third yoke 53. Each of the first yoke 51, the second yoke 52, and the third yoke 53 includes a soft magnetic material. The spacer 50 includes a nonmagnetic material.

  As shown in FIG. 5A, the first yoke 51 includes a first base portion 51a and a plurality of first tooth portions 51b. The first base 51a has a ring shape. The plurality of first tooth portions 51b protrude upward from the first base portion 51a. The plurality of first tooth portions 51b are arranged at equal intervals along the circumferential direction of the first base portion 51a.

  As shown in FIG. 5B, the second yoke 52 includes a second base portion 52a and a plurality of second tooth portions 52b. The second base 52a has a ring shape. The plurality of second tooth portions 52b protrude upward from the second base portion 52a. The plurality of second tooth portions 52b are arranged at equal intervals along the circumferential direction of the second base portion 52a. The length of each second tooth portion 52 b is shorter than the length of each first tooth portion 51 b in the first yoke 51.

  As shown in FIG. 5C, the third yoke 53 includes a third base portion 53a and a plurality of third tooth portions 53b. The third base 53a has a ring shape. The multiple third tooth portions 53b protrude downward from the third base portion 53a. The plurality of third tooth portions 53b are arranged at equal intervals along the circumferential direction of the third base portion 53a.

  As shown in FIG. 4, the magnetic yoke member 5 has a ring shape as a whole. The magnetic yoke member 5 is attached to the output shaft portion 102 of the steering shaft 100. The magnetic yoke member 5 is disposed concentrically with the magnet 2.

  The first base 51 a of the first yoke 51 has a portion extending along the rotation direction of the steering shaft 100. The plurality of first tooth portions 51 b are opposed to the magnet 2 in the radial direction of the steering shaft 100 while protruding from the first base portion 51 a in the direction along the rotation axis A of the steering shaft 100.

  The second base 52 a of the second yoke 52 has a portion extending along the rotation direction of the steering shaft 100. The plurality of second tooth portions 52 b are opposed to the magnet 2 in the radial direction of the steering shaft 100 while protruding from the second base portion 52 a in the direction along the rotation axis A of the steering shaft 100.

  The third base 53 a of the third yoke 53 has a portion extending along the rotation direction of the steering shaft 100. The plurality of third tooth portions 53 b are opposed to the magnet 2 in the radial direction of the steering shaft 100 while protruding from the third base portion 53 a in the direction along the rotation axis A of the steering shaft 100.

  The magnetic yoke member 5 is integrally formed by the spacer 50 so that the first yoke 51 and the second yoke 52 are separated in the direction along the rotational axis A of the steering shaft 100. The magnetic yoke member 5 is integrally formed with the spacer 50 so that the second yoke 52 and the third yoke 53 are adjacent to each other in the direction along the rotation axis A. The first yoke 51, the second yoke 52, and the third yoke 53 are arranged in the direction along the rotation axis A in this order from the top.

  The torque detection device 1 </ b> B includes a detection unit 4. The detection unit 4 is configured to detect a magnetic field and output a signal corresponding to the detected magnetic field. The detection unit 4 includes a magnetic detection element such as a Hall element or a magnetoresistive element. The detector 4 is disposed between the first base 51 a of the first yoke 51 and the second base 52 a of the second yoke 52 in the direction along the rotation axis A of the steering shaft 100. Specifically, the detection unit 4 is configured to detect a magnetic flux generated between the first base 51a and the second base 52a and output a detection signal corresponding to the density of the magnetic flux. The detection signal is sent to a control device such as an ECU for signal processing.

  In the present embodiment, the plurality of second tooth portions 52 b in the second yoke 52 protrude in the same direction as the plurality of first tooth portions 51 b in the first yoke 51 and in the direction approaching the first base portion 51 a. The plurality of third tooth portions 53b in the third yoke 53 protrude in the direction opposite to the plurality of second tooth portions 52b in the second yoke 52 and away from the second base portion 52a.

  As shown in FIG. 6B, the plurality of third tooth portions 53 b in the third yoke 53 are at the same position along the rotation direction of the plurality of second tooth portions 52 b in the second yoke 52 and the steering shaft 100. , Protruding from the third base 53a.

  As described above, the length of each second tooth portion 52 b in the second yoke 52 is shorter than the length L 5 of each first tooth portion 51 b in the first yoke 51. The length of each third tooth portion 53b in the third yoke 53 is such that the total length of the second tooth portion 52b and the third tooth portion 53b is substantially equal to the length L5 of the first tooth portion 51b. It is determined to be.

  FIG. 6A shows the same comparative example as that shown in FIG. As is clear from the comparison between the two, according to the configuration of the present embodiment, the plurality of first tooth portions 51b and the plurality of second tooth portions 52b are made while the gap G5 between the first base portion 51a and the second base portion 52a is narrowed. And the area which receives magnetic flux by the several 3rd tooth part 53b can be increased. Therefore, the detection accuracy of the magnetic field by the detection unit 4 is improved.

  In addition, as is apparent from the comparison with the first embodiment shown in FIG. 3B, the magnetic yoke in the direction along the rotation axis A of the steering shaft 100 necessary to obtain the same tooth length. The size of the member can be made smaller.

  In the present embodiment, the first yoke 51 is a single member having an annular first base portion 51a. However, the first yoke 51 can be constituted by a plurality of members having an arc-shaped first base portion extending along the rotation direction of the steering shaft 100.

  Similarly, the second yoke 52 is a single member having an annular second base portion 52a. However, the second yoke 52 can be constituted by a plurality of members having an arc-shaped second base portion extending along the rotation direction of the steering shaft 100.

  Similarly, the third yoke 53 is a single member having an annular third base portion 53a. However, the third yoke 53 can be constituted by a plurality of members having an arc-shaped third base portion extending along the rotation direction of the steering shaft 100.

  FIG. 7 schematically shows the configuration of a torque detection device 1C according to the third embodiment. The torque detection device 1C is an example of a magnetic field detection device. Constituent elements having substantially the same configurations and functions as those described with reference to the torque detection device 1A according to the first embodiment are given the same reference numerals, and repeated descriptions are omitted.

  The torque detection device 1 </ b> C includes a magnetic yoke member 6. The magnetic yoke member 6 includes a spacer 60, a first yoke 61, a second yoke 62, a third yoke 63, and a fourth yoke 64. Each of the first yoke 61, the second yoke 62, the third yoke 63, and the fourth yoke 64 includes a soft magnetic material. The spacer 60 includes a nonmagnetic material.

  As shown in FIG. 8A, the third yoke 63 includes a third base portion 63a and a plurality of third tooth portions 63b. The third base portion 63a has a ring shape. The plurality of third tooth portions 63b protrude upward from the third base portion 63a. The plurality of third tooth portions 63b are arranged at equal intervals along the circumferential direction of the third base portion 63a.

  As shown in FIG. 8B, the first yoke 61 includes a first base portion 61a and a plurality of first tooth portions 61b. The first base portion 61a has a ring shape. The plurality of first tooth portions 61b protrude downward from the first base portion 61a. The plurality of first tooth portions 61b are arranged at equal intervals along the circumferential direction of the first base portion 61a.

  As shown in FIG. 8C, the second yoke 62 includes a second base portion 62a and a plurality of second tooth portions 62b. The second base portion 62a has an annular shape. The plurality of second tooth portions 62b protrude upward from the second base portion 62a. The plurality of second tooth portions 62b are arranged at equal intervals along the circumferential direction of the second base portion 62a.

  As shown in FIG. 8D, the fourth yoke 64 includes a fourth base portion 64a and a plurality of fourth tooth portions 64b. The fourth base portion 64a has a ring shape. The plurality of fourth tooth portions 64b protrude downward from the fourth base portion 64a. The plurality of fourth tooth portions 64b are arranged at equal intervals along the circumferential direction of the fourth base portion 64a.

  As shown in FIG. 7, the magnetic yoke member 6 has an annular shape as a whole. The magnetic yoke member 6 is attached to the output shaft portion 102 of the steering shaft 100. The magnetic yoke member 6 is disposed concentrically with the magnet 2.

  The first base 61 a of the first yoke 61 has a portion extending along the rotation direction of the steering shaft 100. The plurality of first tooth portions 61 b are opposed to the magnet 2 in the radial direction of the steering shaft 100 while protruding from the first base portion 61 a in the direction along the rotation axis A of the steering shaft 100.

  The second base 62 a of the second yoke 62 has a portion extending along the rotation direction of the steering shaft 100. The plurality of second tooth portions 62 b are opposed to the magnet 2 in the radial direction of the steering shaft 100 while protruding from the second base portion 62 a in the direction along the rotation axis A of the steering shaft 100.

  The third base 63 a of the third yoke 63 has a portion that extends along the rotational direction of the steering shaft 100. The plurality of third tooth portions 63 b face the magnet 2 in the radial direction of the steering shaft 100 while protruding from the third base portion 63 a in the direction along the rotation axis A of the steering shaft 100.

  The fourth base portion 64 a of the fourth yoke 64 has a portion extending along the rotation direction of the steering shaft 100. The plurality of fourth tooth portions 64 b are opposed to the magnet 2 in the radial direction of the steering shaft 100 while protruding from the fourth base portion 64 a in a direction along the rotation axis A of the steering shaft 100.

  The magnetic yoke member 6 is integrally molded by the spacer 60 so that the first yoke 51 and the second yoke 52 are separated in the direction along the rotational axis A of the steering shaft 100. Further, in the magnetic yoke member 6, the first yoke 61 and the third yoke 63 are adjacent to each other along the rotation axis A, and the second yoke 62 and the fourth yoke 64 are adjacent to each other along the rotation axis A. Thus, it is integrally formed with the spacer 60. The third yoke 63, the first yoke 61, the second yoke 62, and the fourth yoke 64 are arranged in the direction along the rotation axis A in this order from above.

  The torque detection device 1 </ b> C includes a detection unit 4. The detection unit 4 is configured to detect a magnetic field and output a signal corresponding to the detected magnetic field. The detection unit 4 includes a magnetic detection element such as a Hall element or a magnetoresistive element. The detector 4 is disposed between the first base 61 a of the first yoke 61 and the second base 62 a of the second yoke 62 in the direction along the rotation axis A of the steering shaft 100. Specifically, the detection unit 4 is configured to detect a magnetic flux generated between the first base 61a and the second base 62a and output a detection signal corresponding to the density of the magnetic flux. The detection signal is sent to a control device such as an ECU for signal processing.

  In the present embodiment, the plurality of second tooth portions 62b in the second yoke 62 protrude in the direction opposite to the plurality of first tooth portions 61b in the first yoke 61 and in the direction approaching the first base portion 61a. The plurality of third tooth portions 63b in the third yoke 63 protrude in a direction opposite to the plurality of first tooth portions 61b in the first yoke 61 and away from the first base portion 61a. The plurality of fourth tooth portions 64b in the fourth yoke 64 protrude in a direction opposite to the plurality of second tooth portions 62b in the second yoke 62 and away from the second base portion 62a.

  As shown in FIG. 9B, the plurality of third tooth portions 63 b in the third yoke 63 are in the same position along the rotation direction of the plurality of first tooth portions 61 b in the first yoke 61 and the steering shaft 100. , Protruding from the third base 63a. The plurality of fourth tooth portions 64 b in the fourth yoke 64 protrude from the fourth base portion 64 a at the same position along the rotation direction of the steering shaft 100 as the plurality of second tooth portions 62 b in the second yoke 62.

  The length of each first tooth portion 61b, the length of each second tooth portion 62b, the length of each third tooth portion 63b, and the length of each fourth tooth portion 64b are the same as the length of the first tooth portion 61b. The total length of the third tooth portion 63b is determined to be substantially equal to the total length of the second tooth portion 62b and the fourth tooth portion 64b (length L6 in this example).

  FIG. 9A shows the same comparative example as that shown in FIG. As apparent from the comparison between the two, according to the configuration of the present embodiment, the plurality of first tooth portions 61b and the plurality of second tooth portions 62b are made while the gap G6 between the first base portion 61a and the second base portion 62a is narrowed. The area receiving the magnetic flux can be increased by the plurality of third tooth portions 63b and the plurality of fourth tooth portions 64b. Therefore, the detection accuracy of the magnetic field by the detection unit 4 is improved.

  In addition, as is clear from comparison with the first embodiment shown in FIG. 3B and the second embodiment shown in FIG. 6B, it is necessary to obtain the same tooth length. The dimension of the magnetic yoke member in the direction along the rotation axis A of the steering shaft 100 can be further reduced.

  In the present embodiment, the first yoke 61 is a single member having an annular first base portion 61a. However, the first yoke 61 may be configured by a plurality of members having an arc-shaped first base portion that extends along the rotation direction of the steering shaft 100.

  Similarly, the second yoke 62 is a single member having an annular second base portion 62a. However, the second yoke 62 can be constituted by a plurality of members having an arc-shaped second base portion extending along the rotation direction of the steering shaft 100.

  Similarly, the third yoke 63 is a single member having an annular third base portion 63a. However, the third yoke 63 can be constituted by a plurality of members having an arc-shaped third base portion extending along the rotation direction of the steering shaft 100.

  Similarly, the fourth yoke 64 is a single member having an annular fourth base portion 64a. However, the fourth yoke 64 can be configured by a plurality of members having an arcuate fourth base portion extending along the rotation direction of the steering shaft 100.

  The above embodiment is merely an example for facilitating understanding of the present invention. The configuration according to the above embodiment can be changed or improved as appropriate without departing from the spirit of the present invention.

  In the above embodiment, the torque applied to the steering shaft 100 in which the input shaft portion 101 and the output shaft portion 102 are coupled so as to be relatively rotatable is detected through the detection of the magnetic field by the detection unit 4. However, the above-described configurations of the magnetic yoke member 3, the magnetic yoke member 5, and the magnetic yoke member 6 can be used to detect the presence or absence of rotation of the rotating member. In this case, the rotating member does not need to include two rotating members coupled so as to be relatively rotatable. The magnet 2 is coupled to the rotating member, and any one of the magnetic yoke member 3, the magnetic yoke member 5, and the magnetic yoke member 6 is disposed concentrically with the magnet 2 as a stator, whereby a magnetic field associated with the rotation of the rotating member. Can be detected by the detection unit 4.

  1A, 1B, 1C: Torque detection device, 2: Magnet, 3: Magnetic yoke member, 31: First yoke, 31a: First base, 31b: First tooth, 32: Second yoke, 32a: Second base 32b: second tooth part, 4: detection part, 5: magnetic yoke member, 51: first yoke, 51a: first base part, 51b: first tooth part, 52: second yoke part, 52a: second base part, 52b: second tooth part, 53: third yoke, 53a: third base part, 53b: third tooth part, 6: magnetic yoke member, 61: first yoke, 61a: first base part, 61b: first tooth part 62: second yoke, 62a: second base, 62b: second tooth, 63: third yoke, 63a: third base, 63b: third tooth, 64: fourth yoke, 64a: fourth base 64b: fourth tooth portion, 100: steering shaft, 101: input shaft portion, 102: output shaft portion A: axis of rotation

Claims (4)

A magnetic field source coupled to the rotating member;
A magnetic yoke member including a first yoke and a second yoke arranged in a direction along the rotation axis of the rotating member;
A detection unit that detects a magnetic field and outputs a signal corresponding to the detected magnetic field;
With
The first yoke is
A first base having a portion extending along the direction of rotation of the rotating member;
A plurality of first teeth protruding from the first base along the rotation axis and facing the magnetic field generation source in a direction intersecting the rotation axis;
With
The second yoke is
A second base having a portion extending along the rotational direction;
A plurality of second teeth protruding from the second base along the rotation axis and facing the magnetic field generation source in a direction intersecting the rotation axis;
With
The detector is disposed between the first base and the second base in the direction along the rotation axis,
The plurality of second tooth portions project in a direction opposite to the plurality of first tooth portions and away from the first base portion,
Magnetic field detection device. A magnetic field source coupled to the rotating member;
A magnetic yoke member including a first yoke, a second yoke, and a third yoke arranged in a direction along the rotation axis of the rotating member;
A detection unit that detects a magnetic field and outputs a signal corresponding to the detected magnetic field;
With
The first yoke is
A first base having a portion extending along the direction of rotation of the rotating member;
A plurality of first teeth protruding from the first base along the rotation axis and facing the magnetic field generation source in a direction intersecting the rotation axis;
With
The second yoke is
A second base having a portion extending along the rotational direction;
A plurality of second teeth protruding from the second base along the rotation axis and facing the magnetic field generation source in a direction intersecting the rotation axis;
With
The third yoke is
A third base having a portion extending along the rotational direction;
A plurality of second teeth protruding from the third base along the rotation axis at the same position along the rotation direction as the plurality of second teeth and facing the magnetic field generation source in a direction intersecting the rotation axis. Three teeth,
With
The detector is disposed between the first base and the second base in the direction along the rotation axis,
The plurality of second teeth protrudes in the same direction as the plurality of first teeth and in a direction approaching the first base,
The length of the plurality of second tooth portions in the direction along the rotation axis is shorter than the length of the plurality of first tooth portions in the same direction,
The plurality of third teeth protrudes in a direction opposite to the plurality of second teeth and away from the second base.
Magnetic field detection device. A magnetic field source coupled to the rotating member;
A magnetic yoke member including a first yoke, a second yoke, a third yoke, and a fourth yoke arranged in a direction along the rotation axis of the rotating member;
A detection unit that detects a magnetic field and outputs a signal corresponding to the detected magnetic field;
With
The first yoke is
A first base having a portion extending along the direction of rotation of the rotating member;
A plurality of first teeth protruding from the first base along the rotation axis and facing the magnetic field generation source in a direction intersecting the rotation axis;
With
The second yoke is
A second base having a portion extending along the rotational direction;
The plurality of first teeth projecting from the second base along the rotation axis at different positions along the rotation direction with the plurality of first teeth and facing the magnetic field generation source in a direction intersecting the rotation axis. Two teeth,
With
The third yoke is
A third base having a portion extending along the rotational direction;
A plurality of first teeth protruding from the third base along the rotation axis at the same position along the rotation direction as the plurality of first teeth and facing the magnetic field generation source in a direction intersecting the rotation axis. Three teeth,
With
The fourth yoke is
A fourth base having a portion extending along the rotational direction;
A plurality of second teeth protruding from the fourth base along the rotation axis at the same position along the rotation direction as the plurality of second teeth and facing the magnetic field generation source in a direction intersecting the rotation axis. Four teeth,
With
The detector is disposed between the first base and the second base in the direction along the rotation axis,
The plurality of second tooth portions project in a direction opposite to the plurality of first tooth portions and in a direction approaching the first base portion,
The plurality of third tooth portions project in a direction opposite to the plurality of first tooth portions and away from the first base portion,
The plurality of fourth teeth protrudes in a direction opposite to the plurality of second teeth and away from the second base,
Magnetic field detection device. The rotating member includes a first rotating member and a second rotating member that are coupled so as to be relatively rotatable,
The magnetic field generation source is coupled to the first rotating member;
The magnetic yoke member is coupled to the second rotating member;
A torque detector that detects torque applied to the rotating member based on the signal;
The magnetic field detection apparatus according to any one of claims 1 to 3.

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