WO2017090127A1

WO2017090127A1 - Torque sensor

Info

Publication number: WO2017090127A1
Application number: PCT/JP2015/083080
Authority: WO
Inventors: 隆徳小室; 伸幸北井
Original assignee: 日立金属株式会社
Priority date: 2015-11-25
Filing date: 2015-11-25
Publication date: 2017-06-01
Also published as: JP6551538B2; JPWO2017090127A1

Abstract

[Problem] To provide a torque sensor whereby the effect of external magnetic field noise can be suppressed, and torque can be measured with good precision. [Solution] The present invention is provided with: a ring magnet 31 in which a plurality of magnetic poles 311, 312 having different polarities are formed along the circumferential direction, the ring magnet 31 rotating together with a first rotary member 111; magnetic yokes 41, 42 configured so that the positional relationship thereof with the magnetic poles 311, 312 changes and the transmitted magnetic flux changes in response to twisting of a torsion bar; magnetism collecting rings 51, 52 for collecting the magnetic flux of the magnetic yokes 41, 42, the magnetism collecting rings 51, 52 having opposing parts 513, 523 protruding outward in the radial direction from annular parts 511, 521; a first magnetism detecting element 61 disposed between the opposing parts 513, 523; and a shield member 63 for covering the first magnetism detecting element 61 and the opposing parts 513, 523, the shield member 63 being formed in a cylindrical shape having an opening in the radial direction; the shield member 63 being provided so as to protrude outward in the radial direction further than the first magnetism detecting element 61.

Description

Torque sensor

The present invention relates to a torque sensor.

Conventionally, an electric power steering device for a vehicle is provided with a torque sensor capable of detecting a steering torque (see, for example, Patent Document 1).

The torque sensor is configured to detect the steering torque by detecting the twist angle of the torsion bar that connects the input shaft and the output shaft of the steering shaft. For example, an annular ring magnet having a plurality of magnetic poles having different polarities along the circumferential direction is provided on the input shaft, and the relative angle between the output shaft and the ring magnet changes according to the twist of the torsion bar. Provided with a magnetic path forming member configured such that the positional relationship with the magnetic pole changes and the transmitted magnetic flux changes according to the change in relative angle, and the magnetic flux guided by the magnetic path forming member is used as a pair of magnetic flux collecting rings The torsion angle of the torsion bar, i.e., the steering torque, can be detected by collecting and collecting the magnetic flux between the magnetic flux collecting rings.

Japanese Patent No. 5193110

However, in the conventional torque sensor as described above, a part of the magnetic flux generated by the ring magnet, the magnetic flux generated by an external device (hereinafter referred to as external magnetic field noise) or the like is generated by the magnetic path forming member or the magnetic flux collecting ring. There is a problem in that the magnetic sensor element is reached without going through and causes an error in torque measurement.

Therefore, an object of the present invention is to provide a torque sensor capable of suppressing the influence of external magnetic field noise and measuring torque with high accuracy.

In order to solve the above-described problems, the present invention provides a torque sensor disposed at a connecting portion between a first rotating member and a second rotating member connected by a torsion bar, the first rotating member and the first rotating member. A plurality of magnetic poles having different polarities are formed along a circumferential direction around the rotation axis of the two-rotating member, an annular ring magnet that rotates together with the first rotating member, and the magnetic pole according to the twist of the torsion bar Of the plurality of magnetic path forming members configured to change the positional magnetic fluxes to be transmitted, a pair of magnetic flux collecting rings for collecting the magnetic fluxes of the magnetic path forming members, and the pair of magnetic flux collecting rings A magnetic detection element for torque detection capable of detecting the strength of the magnetic field between the pair of magnetism collecting rings, the annular portion arranged coaxially with the ring magnet, and the same circumferential direction of the annular portion Place Projecting outward in the radial direction from each other, and facing portions provided so as to face each other in the axial direction, and the torque detecting magnetic detection element is disposed between the both facing portions, And is formed in a cylindrical shape having an opening in the radial direction of the annular portion, and is spaced apart from the magnetism collecting ring so as to cover the torque detection magnetic detection element and the opposing portions. And providing a torque sensor provided so that the shield member does not protrude outward in the radial direction from the magnetic detection element for torque detection.

According to the present invention, it is possible to provide a torque sensor that can suppress the influence of external magnetic field noise and accurately measure torque.

1 is a schematic diagram illustrating an electric power steering apparatus to which a torque steering angle sensor as a torque sensor according to an embodiment of the present invention is applied. It is a side view which shows a torque steering angle sensor. It is a bottom view of FIG. 2A. It is a perspective view which shows the structure of a torque detection part. It is a perspective view which shows a 1st magnetic yoke. It is a perspective view which shows a 2nd magnetic yoke. It is a graph which shows the simulation result of the influence of external magnetic field noise when changing the length Ls along the radial direction of a shield member. It is a graph which shows the relationship between the angle error which converted the magnetic flux density detected by the 1st magnetic detection element into the reluctator angle by the influence of an external magnetic field, and length Ls of a shield member. It is a schematic diagram which shows the direction of the magnetic flux obtained by magnetic flux analysis, when length Ls of a shield member is 8 mm. It is a schematic diagram which shows the direction of the magnetic flux obtained by magnetic flux analysis, when length Ls of a shield member is 0.5 mm. It is a graph which shows the simulation result of the amplitude of the magnetic flux density detected with a 1st magnetic detection element by the influence of an external magnetic field noise when the end surface distance D and the length Ls of a shield member are changed.

[Embodiment]
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

(Configuration of electric steering device)
FIG. 1 is a schematic diagram showing an electric power steering apparatus 1 to which a torque steering angle sensor 2 according to the present embodiment is applied. The torque steering angle sensor 2 is an aspect of the torque sensor of the present invention.

The electric power steering apparatus 1 includes a steering shaft 11 connected to a steering wheel 10, an intermediate shaft 13 connected to the steering shaft 11 via a universal joint 12, and an intermediate shaft 13 via a universal joint 14. Steering according to the steering torque applied to the steering shaft 11 when the steering wheel 10 is steered, and the rack shaft 16 formed with the rack teeth 160 meshing with the pinion teeth 150 of the pinion shaft 15. A steering assist mechanism 17 that generates an assist force and a torque steering angle sensor 2 that detects the steering angle and steering torque of the steering wheel 10 are provided.

The rack shaft 16 is supported by a rack housing (not shown) and moves in the vehicle width direction according to the steering operation of the steering wheel 10. The left and right

front wheels

19L and 19R, which are steered wheels, and the rack shaft 16 are connected by left and

right tie rods

18L and 18R. The rack shaft 16 and the pinion shaft 15 constitute a rack and pinion type steering mechanism.

In the present embodiment, the steering assist mechanism 17 is a rack assist type steering assist mechanism that applies a steering assist force to the rack shaft 16, and the rotational force of the electric motor 170 is converted into a linear moving force by, for example, a ball screw mechanism. Then, it is applied to the rack shaft 16 as a steering assist force. However, the steering assist mechanism 17 is provided on a steering column that supports the steering shaft 11, and is a column assist type that decelerates the rotational force of the electric motor 170 by, for example, a worm gear mechanism and applies the steering assist force to the steering shaft 11. It may be.

The steering assist mechanism 17 is supplied with a motor current from the control device 20 and generates a steering assist force corresponding to the motor current. The control device 20 includes a steering torque calculation unit 21a and a steering angle calculation unit 21b, which will be described later, and a torque / steering angle calculation unit 21 that calculates a steering torque and a steering angle based on an output signal of the torque steering angle sensor 2. A steering assist force calculator 22 that calculates a steering assist force to be applied based on the calculation result of the steering angle calculator 21 and a motor current corresponding to the steering assist force calculated by the steering assist force calculator 22 are output. And a motor drive circuit 23 for driving the electric motor 170 of the steering assist mechanism 17.

The steering assist force calculating unit 22 increases the steering assist force applied to the steering mechanism by the steering assist mechanism 17 as the steering torque increases and as the steering speed calculated based on the temporal change in the steering angle increases. The operation is performed as follows. The steering angle calculated by the torque / steering angle calculation unit 21 is also used for control in, for example, a vehicle skid prevention device (ESCＥＳ: Electronic Stability Control).

The steering shaft 11 includes a first rotating member 111 on the steering wheel 10 side and a second rotating member 112 on the intermediate shaft 13 side, and the first rotating member 111 and the second rotating member 112 are not illustrated. It is connected by a torsion bar. The torque steering angle sensor 2 is disposed at a connecting portion between the first rotating member 111 and the second rotating member 112. In the present embodiment, the torque steering angle sensor 2 is disposed on the steering shaft 11. However, the present invention is not limited to this, and the torque steering angle sensor 2 may be disposed on the pinion shaft 15, for example.

(Configuration of torque steering angle sensor)
Next, the configuration of the torque steering angle sensor 2 will be described. In the following description, for convenience of explanation, the steering wheel 10 side in the axial direction of the steering shaft 11 is described as “up” and the opposite side (intermediate shaft 13 side) is described as “down”. Alternatively, “down” does not limit the vertical direction in the usage state of the electric power steering apparatus 1.

FIG. 2A is a side view showing the torque steering angle sensor 2, and FIG. 2B is a bottom view thereof.

The first rotating member 111 and the second rotating member 112 of the steering shaft 11 share the rotation axis O and rotate together with the steering wheel 10. The first rotating member 111 and the second rotating member 112 are connected by a torsion bar (not shown) that generates a twist angle according to the steering torque of the steering wheel 10. One end of the torsion bar in the axial direction is coupled to the first rotating member 111 so as not to be relatively rotatable, and the other end is coupled to the second rotating member 112 so as not to be relatively rotatable. The torque steering angle sensor 2 is disposed at a connecting portion between the first rotating member 111 and the second rotating member 112.

The torque steering angle sensor 2 includes a torque detection unit 2a for detecting the steering torque and a steering angle detection unit 2b for detecting the steering angle, and a column housing (not configured) that holds the steering shaft 11 so that the tilt adjustment is possible. (Shown). The column housing is an aspect of the “non-rotating member” of the present invention that does not rotate by the rotation of the first rotating member 111.

(Configuration of the torque detector 2a)
3A is a perspective view showing the configuration of the torque detector 2a, FIG. 3B is a perspective view showing the first magnetic yoke, and FIG. 3B is a perspective view showing the second magnetic yoke.

As shown in FIGS. 2A and 2B and FIGS. 3A to 3C, the torque detector 2a includes an annular ring magnet 31 that rotates together with the first rotating member 111, and a plurality of magnetic paths that form a magnetic path of magnetic flux by the ring magnet 31. A pair of magnetic flux collectors that collect the magnetic fluxes of the first magnetic yoke 41 and the second magnetic yoke 42, and the first magnetic yoke 41 and the second magnetic yoke 42 as the forming member (retractor). And a first magnetic detection element 61 capable of detecting the strength of the magnetic field between the pair of magnetism collecting rings 51 and 52, and based on the strength of the magnetic field detected by the first magnetic detection element 61. Further, the steering torque of the steering wheel 10 is calculated. The first magnetic detection element 61 is an aspect of the torque detection magnetic detection element of the present invention.

The ring magnet 31 is formed with a plurality of magnetic poles having different magnetism along the circumferential direction around the rotation axis O. In the present embodiment, eight magnetic poles including four N poles 311 and four S poles 312 are formed on the ring magnet 31.

The magnetism collecting rings 51 and 52 are arranged at a position (here, below) shifted from the ring magnet 31 in the axial direction (rotational axis direction). The magnetic flux collecting rings 51 and 52 include a first magnetic flux collecting ring 51 and a second magnetic flux collecting ring 52 disposed above the first magnetic flux collecting ring 51, and more than both the magnetic flux collecting rings 51 and 52. Further, a ring magnet 31 is disposed above. Both the magnetism collecting rings 51 and 52 are provided apart from the rotating

members

111 and 112 so as not to rotate with the rotation of the

rotating members

111 and 112, and are fixed to a non-rotating member such as a column housing. ing.

The magnetism collecting rings 51 and 52 are formed in a cylindrical shape in which the axial width is larger than the radial thickness, and the

annular portions

511 and 521 arranged coaxially with the ring magnet 31, and the circumferences of the

annular portions

511 and 521 And opposing

portions

513 and 523 provided so as to protrude radially outward from the same position in the direction and to face each other in the axial direction.

Here, the connecting portion 512 is integrally provided so as to extend upward from the upper end portion of the annular portion 511 of the first magnetism collecting ring 51, and the facing portion 513 is protruded radially outward from the connecting portion 512. It is provided integrally. Further, in the second magnetism collecting ring 52, a connecting portion 522 is integrally provided so as to extend downward from the lower end portion of the annular portion 521, and the facing portion 523 is protruded radially outward from the connecting portion 522. It is provided integrally. Both facing

parts

513 and 523 are provided so as to face each other in the axial direction at a predetermined interval. Between the facing

parts

513 and 523, a first magnetic sensing element 61 as a torque sensing magnetic sensing element is disposed. ing.

The first magnetic detection element 61 is, for example, a Hall IC that detects the strength of the magnetic field using the Hall effect. The output signal of the first magnetic detection element 61 is output to the torque / steering angle calculation unit 21 of the control device 20.

The first magnetic yoke 41 and the second magnetic yoke 42 as magnetic path forming members are held by a holding member (not shown) made of resin or the like and are fixed to the second rotating member 112, and rotate together with the second rotating member 112. It is provided to do.

The first magnetic yoke 41 is configured to magnetically couple the ring magnet 31 and the first magnetism collecting ring 51, and the second magnetic yoke 42 magnetically couples the ring magnet 31 and the second magnetism collecting ring 52. It is comprised so that it may couple | bond with.

The first magnetic yoke 41 includes a facing piece 411 facing in parallel with the axial end surface of the ring magnet 31, a delivery part 413 that delivers magnetic flux between the annular part 511 of the first magnetic flux collecting ring 51, and a facing piece 411. And a transfer portion 412 that transmits magnetic flux between the transfer portion 413 and the transfer portion 413. The transmission unit 412 includes an axial transmission unit 412a parallel to the rotation axis O, a radial transmission unit 412b extending radially from the lower end of the axial transmission unit 412a toward the annular portion 511 of the first magnetic flux collecting ring 51, and Consists of. The delivery part 413 is formed in a plate shape that faces the inner peripheral surface 511 a of the annular part 511 of the first magnetic flux collecting ring 51 in the radial direction.

The second magnetic yoke 42 includes a counter piece 421 that faces the end face in the axial direction of the ring magnet 31 in parallel, a transfer portion 423 that transfers magnetic flux between the annular portion 521 of the second magnetism collecting ring 52, and a counter piece 421. And a transfer part 422 that transmits magnetic flux between the transfer part 423 and the transfer part 423. The transmission part 422 and the transfer part 423 are made of a single flat plate, of which the part facing the inner peripheral surface 521a of the annular part 521 of the second magnetism collecting ring 52 is the transfer part 423, which is more than the transfer part 423. A portion on the ring magnet 31 side is a transmission portion 422. That is, the transfer part 423 is formed in a plate shape that faces the inner peripheral surface 521a of the annular part 521 of the second magnetism collecting ring 52 in the radial direction.

When the steering torque is not applied to the steering shaft 11, both the

magnetic yokes

41 and 42 are such that the central portions of the facing

pieces

411 and 421 face the boundary between the N pole 311 and the S pole 312 of the ring magnet 31. Is provided. In this state, the intensity of the magnetic field detected by the first magnetic detection element 61 is substantially zero.

Here, when a steering torque is applied to the steering shaft 11 and the torsion bar is twisted, the ring magnet 31 and the first and second

magnetic yokes

41 and 42 are relatively rotated by the twist, and the magnetic pole ( The opposing positions of the opposing

pieces

411 and 421 of the first and second

magnetic yokes

41 and 42 with respect to the N pole 311 and the S pole 312 are shifted in the circumferential direction of the ring magnet 31.

For example, when the ring magnet 31 rotates with respect to the first and second

magnetic yokes

41 and 42 by a predetermined angle (for example, 5 °) in the direction of arrow A in FIG. The ratio of the N pole 311 to the magnetic poles of the ring magnet 31 facing the S is higher than that of the S pole 312. The proportion of the S pole 312 in the magnetic poles of the ring magnet 31 facing the opposing piece 421 of the second magnetic yoke 42 in the axial direction is higher than that of the N pole 311. As a result, a part of the magnetic flux emitted from the N pole 311 passes through the first magnetic detection element 61 via the first magnetic yoke 41 and the first magnetic flux collecting ring 51, and the second magnetic flux collecting ring 52 and the second magnetic yoke. After 42, return to the S pole 312.

On the other hand, when the ring magnet 31 rotates in the direction opposite to the arrow A direction with respect to the first and second

magnetic yokes

41 and 42, the ring magnet that faces the opposing piece 411 of the first magnetic yoke 41 in the axial direction. Of the 31 magnetic poles, the ratio of the S pole 312 is higher than that of the N pole 311, and the ratio of the N pole 311 among the magnetic poles of the ring magnet 31 that axially opposes the facing piece 421 of the second magnetic yoke 42. Becomes higher than the S pole 312. Thereby, the magnetic flux passes through the first magnetic detection element 61 in the direction opposite to the above.

The strength (absolute value) of the magnetic field detected by the first magnetic detection element 61 increases as the torsion amount of the torsion bar, that is, the relative angle between the ring magnet 31 and the magnetic yokes 41 and 42 (hereinafter referred to as a reluctor angle) increases. Become stronger. As described above, the reluctance angle changes according to the twist of the torsion bar, and the positional relationship between the

magnetic yokes

41 and 42 and the

magnetic poles

311 and 312 changes according to the change of the reluctance angle. The magnetic flux transmitted to is changed. As a result, the intensity of the magnetic field detected by the first magnetic detection element 61 changes, and the direction of the magnetic field is switched according to the twisting direction of the torsion bar.

The torque / steering angle calculator 21 is a reactor angle that is a relative angle between the ring magnet 31 and the magnetic path forming members (magnetic yokes 41 and 42) based on the strength of the magnetic field detected by the first magnetic detection element 61. And the steering torque of the steering wheel 10 is calculated based on the determined reactor angle.

In the present embodiment, the shield member 63 is provided so as to cover the first magnetic detection element 61 and the opposing

portions

513 and 523. Details of the shield member 63 will be described later.

(Configuration of Steering Angle Detection Unit 2b)
As shown in FIG. 2, the steering angle detection unit 2 b includes a ring magnet 31, a second magnetic detection element 62 that is fixed to the substrate 82 at a position where the magnetic field from the ring magnet 31 is received, and a second magnetic detection element 62. A slide magnet 32 that generates a magnetic field in a direction different from that of the ring magnet 31 in the magnetic detection element 62, and the slide magnet 32 approaches and separates from the second magnetic detection element 62 as the first rotation member 111 rotates. The slide mechanism 7 that moves in the direction and the steering angle calculation unit 21b that calculates the steering angle of the steering wheel 10 based on the strength of the magnetic field detected by the second magnetic detection element 62 are provided. The ring magnet 31 is a component of the torque detector 2a and a component of the steering angle detector 2b.

The second magnetic detection element 62 is disposed on a non-rotating member that does not rotate by the rotation of the first rotating member 111 so as to face the outer peripheral surface of the ring magnet 31. As the second magnetic detection element 62, there are 3 in the radial direction (X direction) of the ring magnet 31, an axial direction parallel to the rotation axis O (Y direction), and a tangential direction (Z direction) perpendicular to the radial direction and the axial direction. A triaxial magnetic detection element capable of detecting the strength of the magnetic field in the direction is used. The distance (distance along the radial direction) between the second magnetic detection element 62 and the ring magnet 31 is, for example, 15 mm.

The second magnetic detection element 62 can detect the magnetic field received from the ring magnet 31 by detecting the magnetic field in the X direction and the Z direction. The second magnetic detection element 62 can detect the strength of the magnetic field received from the slide magnet 32 by detecting the magnetic field in the Y direction parallel to the rotation axis O.

The second magnetic detection element 62 is, for example, a Hall IC that detects the strength of the magnetic field using the Hall effect. The output signal of the second magnetic detection element 62 is output to the torque / steering angle calculation unit 21 of the control device 20.

The slide magnet 32 is arranged to face the second magnetic detection element 62 in the axial direction (Y direction). The slide magnet 32 has a magnetization direction parallel to the rotation axis O, and magnetic poles (N pole 321 and S pole 322) having different polarities are formed along the axial direction (Y direction). Thereby, the slide magnet 32 is configured to suppress the magnetic field generated in the X direction and the Z direction with respect to the second magnetic detection element 62. In the present embodiment, the slide magnet 32 is arranged such that the N pole 321 faces the second magnetic detection element 62.

Further, the slide magnet 32 and the second magnetic detection element 62 are arranged so as to sandwich the rotation axis O between the first magnetic detection element 61. Thereby, it is suppressed that the magnetic field of the slide magnet 32 affects the detection result of the magnetic field intensity by the first magnetic detection element 61.

The slide mechanism 7 moves the slide magnet 32 along the axial direction (Y direction) as the first rotating member 111 rotates. The slide mechanism 7 slides as an annular member that rotates together with the slider 71 as a support member that supports the slide magnet 32 and the first rotating member 111 and has a meshing portion 700 that meshes with the slider 71 on the outer peripheral surface. Drive member 70. Although not shown, the slide mechanism 7 may include a guide member that is fixed to a non-rotating member such as a column housing and guides the slider 71 in parallel with the rotation axis O. The slide drive member 70 and the slider 71 are made of a nonmagnetic material such as a nonmagnetic metal such as aluminum or austenitic stainless steel or a hard resin.

The slide driving member 70 is formed in a cylindrical shape into which the first rotating member 111 is inserted, and is fixed to the first rotating member 111. The ring magnet 31 is fixed to the lower end portion of the slide drive member 70 by, for example, adhesion. The slide drive member 70 is formed such that the outer diameter of the lower end portion thereof is smaller than the outer diameter of the meshing portion 700, and the ring magnet 31 is fitted on the outer peripheral surface of the lower end portion.

The meshing portion 700 is formed by providing a single spiral groove on the outer peripheral surface of the slide drive member 70. Even when the steering wheel 10 is steered to the maximum left and right steering angles, the meshing part 700 moves the slide magnet 32 in the direction of approaching and separating from the second magnetic detection element 62 by meshing with the slider 71. It is formed in a possible range.

The slider 71 includes an annular ring portion 711 in which a slider-side engagement portion (not shown) that engages with the engagement portion 700 of the slide drive member 70 is formed on the inner peripheral surface, and a radial direction from a part of the ring portion 711 in the circumferential direction. And a support portion 712 that is provided so as to protrude outward and supports the slide magnet 32. When the slide drive member 70 rotates together with the first rotating member 111, the slider 71 moves up and down due to the meshing between the meshing portion 700 and the slider-side meshing portion.

In the steering angle detection unit 2 b, when the slide magnet 32 supported by the slider 71 moves downward together with the slider 71, the distance between the slide magnet 32 and the second magnetic detection element 62 is shortened and detected by the second magnetic detection element 62. The strength of the magnetic field in the Y direction is increased. On the other hand, when the slide magnet 32 moves upward together with the slider 71, the distance between the slide magnet 32 and the second magnetic detection element 62 increases, and the strength of the magnetic field in the Y direction detected by the second magnetic detection element 62 decreases. .

On the other hand, since the second magnetic detection element 62 is disposed so as to face the outer peripheral surface of the ring magnet 31, when the ring magnet 31 rotates, the N pole 311 and the S pole 312 of the ring magnet 31 alternate with each other. It faces the magnetic detection element 62. Thereby, the intensity of the magnetic field in the X direction and the Z direction changes periodically. Here, since four pairs of the N pole 311 and the S pole 312 are provided in the ring magnet 31, the change period of the intensity of the magnetic field in the X direction and the Z direction is 90 ° (± 45 °).

Therefore, the torque / steering angle calculation unit 21 calculates the ring magnet 31 within an arbitrary period from the intensity of the magnetic field in the X direction and the Z direction based on the intensity of the magnetic field in the three directions detected by the second magnetic detection element 62. The relative rotation angle (hereinafter referred to as the ring angle) is obtained, and the periodic change of the cycle from the reference position based on the strength of the magnetic field in the Y direction (hereinafter referred to as the rotation cycle). The steering angle from the reference position is obtained as an absolute angle from the obtained ring angle and rotation period.

(Description of shield member 63)
Now, in the torque steering angle sensor 2 according to the present embodiment, a part of the magnetic flux generated by the ring magnet 31 and external magnetic field noise such as magnetic flux generated by an external device are caused by the magnetic field strength of the first magnetic detection element 61. A shield member 63 is provided to prevent the detection result from being affected.

The shield member 63 is formed in a cylindrical shape having openings in the radial direction of the

annular portions

511 and 521 of the magnetism collecting rings 51 and 52, and covers the first magnetic detection element 61 and the opposing

portions

513 and 523. The

magnetic rings

51 and 52 are spaced apart from each other.

As the shield member 63, a member made of a ferromagnetic material can be used. For example, a member made of a soft magnetic material such as iron or permalloy can be used. In the present embodiment, a shield member 63 made of iron is used.

Here, the shield member 63 is formed in a rectangular tube shape, but the shape of the shield member 63 is not limited to this, and may be formed in a cylindrical shape, for example. The shield member 63 is attached to the magnetism collecting rings 51 and 52 by a support member (not shown) made of a nonmagnetic material such as a nonmagnetic metal such as aluminum or austenitic stainless steel or a nonmagnetic material such as a hard resin. Supported and fixed.

In the present embodiment, the shield member 63 is provided so as not to protrude outward in the radial direction from the first magnetic detection element 61. As a result of studies by the present inventors, when the shield member 63 is provided so as to protrude radially outward from the first magnetic detection element 61, the effect of suppressing the external magnetic field noise by the shield member 63 is reduced. This is because they have found out.

As an example, a shield member 63 made of an iron square tube having an outer diameter in the axial direction of 7 mm, an inner diameter of 5 mm, an outer diameter in the direction perpendicular to the axial direction (tangential direction) of 8 mm, and an inner diameter of 6 mm is used. 63, when the distance D (hereinafter referred to as end surface distance) D between the base end surface, which is the end surface on the

annular portion

511, 521 side, and the rotation axis O is 19.4 mm, the length along the radial direction of the shield member 63 ( FIG. 4 shows a simulation result of the influence of external magnetic field noise when Ls (hereinafter simply referred to as the length of the shield member 63) is changed. The vertical axis in FIG. 4 represents the magnetic flux density detected by the first magnetic detection element 61 due to the influence of external magnetic field noise (in this case, mainly the influence of the ring magnet 31), and the horizontal axis represents the rotation angle (ring of the ring magnet 31). Angle).

The distance d along the radial direction of the base end face of the shield member 63 and the

annular portions

511 and 521 when the end face distance D is 19.4 mm is 1.5 mm. Further, the protruding lengths (lengths along the radial direction) of the facing

portions

513 and 523 and the first magnetic detection element 61 from the

annular portions

511 and 521 are 2 mm, and the length Ls of the shield member 63 is 2.5 mm or more. If it is larger, it means that the shield member 63 protrudes radially outward from the first magnetic detection element 61.

Further, FIG. 5 shows the relationship between the angle error obtained by converting the magnetic flux density detected by the first magnetic detection element 61 into the reluctator angle due to the influence of the external magnetic field and the length Ls of the shield member 63. 4 and 5 also show the simulation results when the shield member 63 is not provided (no shield).

As shown in FIGS. 4 and 5, it can be seen that the longer the length Ls of the shield member 63, the greater the influence of external magnetic field noise (in this case, the influence of the ring magnet 31), and the greater the angular error. . 4 and 5, the length Ls of the shield member 63 is set to 2.5 mm or less so that the shield member 63 does not protrude outward in the radial direction from the first magnetic detection element 61. It can be seen that the influence of noise is greatly suppressed and the angle error is also reduced. In the case where the shield member 63 is not provided, the influence of external magnetic field noise is larger and the angle error is larger than in the case where the shield member 63 is provided.

The direction of the magnetic flux obtained by the magnetic flux analysis in each case where the length Ls of the shield member 63 is 8 mm and 0.5 mm is schematically shown in FIGS.

As shown in FIG. 6, when the length Ls of the shield member 63 is 8 mm and the shield member 63 protrudes radially outward from the first magnetic detection element 61, the magnetic flux from the ring magnet 31 is the shield member 63. And are discharged to the inner side (hollow part) of the shield member 63. Among these, the magnetic flux emitted from the shield member 63 at the portion protruding radially outward from the first magnetic detection element 61 to the inside of the shield member 63 is directed toward the first magnetic detection element 61. Therefore, it is considered that the magnetic flux density detected by the first magnetic detection element 61, that is, the magnetic flux density detected by the influence of external magnetic field noise is increased.

On the other hand, as shown in FIG. 7, the length Ls of the shield member 63 is shortened to 0.5 mm so that the shield member 63 does not protrude outward in the radial direction from the first magnetic detection element 61. In this case, the magnetic flux emitted from the shield member 63 to the inside of the shield member 63 and directed to the first magnetic detection element 61 is reduced, and the influence of external magnetic field noise is suppressed.

Thus, by providing the shield member 63 so as not to protrude outward in the radial direction from the first magnetic detection element 61, it is possible to suppress the influence of external magnetic field noise and perform torque measurement with high accuracy.

Furthermore, by reducing the length Ls of the shield member 63 and providing the shield member 63 so as to cover only a part of the first magnetic detection element 61 and the opposing

portions

513 and 523 in the radial direction, external magnetic field noise can be reduced. It is possible to further suppress the influence. In other words, the length Ls of the shield member 63 is made shorter than the length in the radial direction of the first magnetic detection element 61 and the opposing

portions

513 and 523, and the first magnetic detection element 61 and the opposing

portions

513 and 523 are By adopting a configuration in which a part is exposed (protruded) from the shield member 63, compared with the case where the entire first magnetic detection element 61 and both opposing

portions

513 and 523 are covered with the shield member 63, external magnetic field noise is reduced. The influence can be further suppressed.

Further, the first magnetic detection element 61 and the opposing

portions

513 and 523 are configured to protrude radially outward from the shield member 63, so that the first magnetic detection element 61 is emitted from the shield member 63 to the inside of the shield member 63. The magnetic flux toward the first magnetic detection element 61 can be reduced, and the influence of external magnetic field noise can be further suppressed.

Next, the end face distance D is 18.4 mm (d = 0.5 mm), 18.9 mm (d = 1.0 mm), 19.4 mm (d = 1.5 mm), 19.9 mm (d = 1.5 mm). In each case, the amplitude of the magnetic flux density detected by the first magnetic detection element 61 due to the influence of the external magnetic field noise when the length Ls of the shield member 63 is changed was obtained by simulation. The simulation results are summarized in FIG.

As shown in FIG. 8, when the end face distance D is 18.4 mm, the influence of external magnetic field noise is minimized when the length Ls of the shield member 63 is 0.9 mm. Similarly, when the end face distance D is 18.9 mm, Ls = 0.6 mm, when the end face distance D is 19.4 mm, Ls = 0.4 mm, and when the end face distance D is 19.9 mm. By setting Ls = 0.3 mm, the influence of external magnetic field noise can be minimized.

From the simulation result of FIG. 8, the longer the end face distance D is (the more the shield member 63 is arranged away from the annular portions 511 and 521), the shorter the length Ls of the shield member 63 is, so that the influence of external magnetic field noise is reduced. It turns out that it becomes possible to suppress more. That is, by appropriately selecting the length Ls of the shield member 63 according to the end face distance D (or the distance d along the radial direction between the base end of the shield member 63 and the annular portions 511 and 521), the external magnetic field noise Can be minimized.

If the length Ls of the shield member 63 is too short, it is difficult to manufacture the shield member 63 with high accuracy. Therefore, the length Ls of the shield member 63 is desirably 0.5 mm or more. Therefore, it can be said that the end face distance D is more preferably 18.9 mm or less (d ≦ 1 mm) that minimizes the influence of the external magnetic field noise when the length Ls of the shield member 63 is 0.5 mm or more.

(Operation and effect of the embodiment)
As described above, the torque steering angle sensor 2 according to the present embodiment is formed of a ferromagnetic material and is formed in a cylindrical shape having openings in the radial direction of the

annular portions

511 and 521, and the first magnetic detection The shield member 63 is provided so as to be separated from the magnetism collecting rings 51 and 52 so as to cover the element 61 and the opposing

portions

513 and 523, and the shield member 63 is radially outward from the first magnetic detection element 61. Is provided so as not to protrude.

By providing the shield member 63, it is possible to suppress the magnetic flux generated from the magnetic flux generation source such as the ring magnet 31 or an external device from affecting the first magnetic detection element 61. Further, by providing the shield member 63 so as not to protrude outward in the radial direction from the first magnetic detection element 61, it is possible to suppress the magnetic flux emitted from the shield member 63 from passing through the first magnetic detection element 61. it can. As a result, the influence of external magnetic field noise can be suppressed and torque can be measured with high accuracy.

In the present embodiment, since the torque steering angle sensor 2 including the steering angle detection unit 2b in addition to the torque detection unit 2a is configured, the shield angle 63 is included to configure the steering angle detection unit 2b. It is also possible to suppress a member such as the slide magnet 32 to adversely affect the torque measurement.

According to the present embodiment, it is possible to suppress the influence of external magnetic field noise only by adjusting the length Ls of the shield member 63 and the position (end surface distance D) where the shield member 63 is mounted. Accurate torque measurement can be realized.

(Summary of embodiment)
Next, the technical idea grasped from the embodiment described above will be described with reference to the reference numerals in the embodiment. However, the reference numerals and the like in the following description do not limit the constituent elements in the claims to members or the like specifically shown in the embodiment.

[1] A torque sensor (2) disposed in a connecting portion between a first rotating member (111) and a second rotating member (112) connected by a torsion bar, the first rotating member (111) and the A plurality of magnetic poles (311 and 312) having different polarities are formed along a circumferential direction around the rotation axis of the second rotating member (112), and an annular ring magnet that rotates together with the first rotating member (111) ( 31) and a plurality of magnetic path forming members (41, 42) configured to change the positional relationship between the magnetic poles (311, 312) and the transmitted magnetic flux according to the twist of the torsion bar, Torque capable of detecting the strength of the magnetic field between the pair of magnetic flux collecting rings (51, 52) collecting magnetic fluxes of the plurality of magnetic path forming members (41, 42) and the pair of magnetic flux collecting rings (51, 52). Magnetic sensing element for detection (61), and the pair of magnetism collecting rings (51, 52) includes an annular portion (511.521) disposed coaxially with the ring magnet (31), and the annular portions (511, 521). ) Projecting radially outward from the same position in the circumferential direction and facing portions (513, 523) provided so as to face each other in the axial direction, and the torque detecting magnetic sensing element (61) , Arranged between the opposing portions (513, 523), made of a ferromagnetic material, and formed in a cylindrical shape having an opening in the radial direction of the annular portion (511, 521), and the torque A shield member (63) disposed apart from the magnetism collecting ring (51, 52) so as to cover the detection magnetic detection element (61) and the opposing portions (513, 523); (63) is the torque Than that of the magnetic detecting element for output (61) is provided so as not to protrude radially outward, the torque sensor (2).

[2] The shield member (63) is configured to cover only part of the torque detection magnetic detection element (61) and the opposing portions (513, 523) in the radial direction. 1] The torque sensor (2).

[3] The torque detection magnetic detection element (61) and the opposing portions (513, 523) are configured to protrude radially outward from the shield member (63). ] The torque sensor (2) described in the above.

[4] A non-rotating member that is not rotated by the rotation of the first rotating member (111) is disposed to face the outer peripheral surface of the ring magnet (31), and the radial direction of the ring magnet (31), the rotation axis, A second magnetic detection element (62) capable of detecting magnetic field strength in three directions of a parallel axial direction and a tangential direction perpendicular to the radial direction and the axial direction; the second magnetic detection element (62); A slide magnet (32) disposed opposite to the axial direction, and a slide mechanism (7) for moving the slide magnet (32) in the axial direction as the first rotating member (111) rotates. The torque sensor (2) according to any one of [1] to [3], further provided.

As mentioned above, although embodiment of this invention was described, embodiment described above does not limit the invention which concerns on a claim. In addition, it should be noted that not all the combinations of features described in the embodiments are essential to the means for solving the problems of the invention.

The present invention can be appropriately modified and implemented without departing from the spirit of the present invention.

For example, in the above embodiment, the torque steering angle sensor 2 including the torque detection unit 2a and the steering angle detection unit 2b has been described. However, the steering angle detection unit 2b is omitted and only torque measurement is possible. Also good.

111 ... 1st rotation member 112 ... 2nd rotation member 2 ... Torque steering angle sensor (torque sensor)
31 ... Ring magnet 311 ... N pole (magnetic pole)
312 ... S pole (magnetic pole)
41 ... 1st magnetic yoke (magnetic path formation member)
42. Second magnetic yoke (magnetic path forming member)
51 ... 1st magnetism collection ring (magnetism collection ring)
52. Second magnetism collecting ring (magnetizing ring)
511, 521 ...

annular portion

513, 523 ... opposing portion 61 ... first magnetic detection element (magnetic detection element for torque detection)
63 ... Shield member

Claims

A torque sensor disposed at a connecting portion between the first rotating member and the second rotating member connected by a torsion bar,
A plurality of magnetic poles having different polarities along a circumferential direction around a rotation axis of the first rotating member and the second rotating member, and an annular ring magnet that rotates together with the first rotating member;
A plurality of magnetic path forming members configured such that the positional relationship with the magnetic poles changes and the magnetic flux to be transmitted changes according to the twist of the torsion bar;
A pair of magnetic flux collecting rings for collecting magnetic fluxes of the plurality of magnetic path forming members;
A torque detecting magnetic sensing element capable of detecting the strength of the magnetic field between the pair of magnetism collecting rings,
The pair of magnetism collecting rings includes an annular portion arranged coaxially with the ring magnet, and an opposing portion provided so as to protrude radially outward from the same position in the circumferential direction of the annular portion and to face the axial direction. Each of which has
The torque detection magnetic detection element is disposed between the opposing portions,
It is made of a ferromagnetic material, is formed in a cylindrical shape having an opening in the radial direction of the annular portion, and is separated from the magnetism collecting ring so as to cover the torque detection magnetic detection element and the opposing portions. Including a shield member to be disposed;
The shield member is provided so as not to protrude outward in the radial direction from the magnetic detection element for torque detection.
Torque sensor.
The shield member is configured to cover only a part of the magnetism detecting element for torque detection and the opposing portions in the radial direction.
The torque sensor according to claim 1.
The magnetic detection element for torque detection and the opposing portions are configured to protrude radially outward from the shield member.
The torque sensor according to claim 2.
A non-rotating member that is not rotated by the rotation of the first rotating member is disposed to face the outer peripheral surface of the ring magnet, and the radial direction of the ring magnet, the axial direction parallel to the rotational axis, and the radial direction and the shaft A second magnetic sensing element capable of detecting the strength of a magnetic field in three directions tangential to the direction;
A slide magnet disposed opposite to the second magnetic detection element in the axial direction;
A slide mechanism that moves the slide magnet in the axial direction along with the rotation of the first rotating member;
The torque sensor according to any one of claims 1 to 3.