JP6551538B2 - Torque sensor - Google Patents

Description

  The present invention relates to a torque sensor.

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

  The torque sensor is configured to detect a steering torque by detecting a twist angle of a torsion bar connecting the input shaft and the output shaft of the steering shaft. For example, while providing an annular ring magnet in which a plurality of magnetic poles of different polarities are formed along the circumferential direction on the input shaft, the relative angle with the ring magnet changes according to the torsion of the torsion bar on the output shaft, 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.

Patent No. 5193110 gazette

  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 that the magnetism detection element is reached without passing through, which causes an error at the time of torque measurement.

  Then, an object of the present invention is to provide a torque sensor capable of accurately measuring torque by suppressing the influence of external magnetic field noise.

  The present invention is a torque sensor disposed at a connecting portion of a first rotating member and a second rotating member connected by a torsion bar, for the purpose of solving the above-mentioned problems, which is characterized in that the first rotating member and the first 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 A plurality of magnetic path forming members configured to change the positional relationship of the magnetic flux and transmitting magnetic flux, a pair of magnetic flux collecting rings for collecting the magnetic flux of the plurality of magnetic path forming members, and the pair of magnetic flux collecting rings And a magnetic detection element for detecting torque capable of detecting the strength of the magnetic field between the two, and the pair of magnetic flux collecting rings are the same in an annular portion coaxially disposed with the ring magnet and in a circumferential direction of the annular portion position And an opposite portion provided radially outward and axially opposed to each other, and the torque detection magnetic detection element is disposed between the two opposite portions, and ferromagnetic It is formed in the shape of a cylinder having a body and an opening in the radial direction of the annular portion, and is disposed apart from the magnetic flux collecting ring so as to cover the torque detection magnetic detection element and the two opposing portions. A torque sensor is provided, the shield member being provided so as not to project radially outward beyond the torque detection magnetic detection element.

  According to the present invention, it is possible to provide a torque sensor capable of accurately measuring the torque while suppressing the influence of external magnetic field noise.

It is a schematic diagram which shows the electric-power-steering apparatus with which the torque steering angle sensor as a torque sensor which concerns on one embodiment of this invention was applied. It is a side view showing a torque steering angle sensor. It is a bottom view of Drawing 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 length Ls along the radial direction of a shield member is changed. 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. 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 schematic diagram which shows the direction of the magnetic flux obtained by magnetic flux analysis. When changing the end surface distance D and the length Ls of a shield member, it is a graph which shows the simulation result of the amplitude of the magnetic flux density detected by a 1st magnetic detection element under the influence of external magnetic field noise.

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

(Configuration of electric steering device)
FIG. 1 is a schematic view 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. The steering assist mechanism 17 generates an assist force, and the torque steering angle sensor 2 detects a steering angle and a steering torque of the steering wheel 10.

  The rack shaft 16 is supported by a rack housing (not shown) and moves in the vehicle width direction in accordance with 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 receives supply of a motor current from the control device 20 and generates a steering assist force corresponding to the motor current. The control device 20 is composed of 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 steering torque and steering angle based on the output signal of the torque steering angle sensor 2. The motor current corresponding to the steering assist force computed by the steering assist force computing unit 22 and the steering assist force computing unit 22 that computes the steering assist force to be applied based on the computation result of the steering angle computing unit 21 is output And a motor drive circuit 23 for driving the electric motor 170 of the steering assist mechanism 17.

  The steering assist force calculation 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. Calculate to be The steering angle calculated by the torque / steering angle calculation unit 21 is also used for control in, for example, a vehicle side slip prevention device (ESC: Electronic Stability Control).

  The steering shaft 11 has 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 shown. 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, “below” does not limit the vertical direction in the use state of the electric power steering apparatus 1.

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

  The first rotation member 111 and the second rotation member 112 of the steering shaft 11 share the rotation axis O and rotate 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 twisting angle according to the steering torque of the steering wheel 10. One end of the torsion bar in the axial direction is non-rotatably connected to the first rotation member 111 and the other end is non-rotationally connected to the second rotation member 112. The torque steering angle sensor 2 is disposed at a connecting portion of the first rotating member 111 and the second rotating member 112.

  The torque steering angle sensor 2 has a torque detection unit 2a for detecting a steering torque, and a steering angle detection unit 2b for detecting a steering angle, and a column housing (not suitable for holding the steering shaft 11 in a tilt adjustable manner). (Shown). The column housing is an aspect of the “non-rotating member” of the present invention which is not rotated by the rotation of the first rotating member 111.

(Configuration of torque detection unit 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 detection unit 2a includes an annular ring magnet 31 that rotates with the first rotating member 111 and a plurality of magnetic paths that form magnetic paths 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 magnetic flux collecting rings 51 and 52, and based on the strength of the magnetic field detected by the first magnetic detection element 61. 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 of different magnetism along the circumferential direction around the rotation axis O. In the present embodiment, eight magnetic poles consisting of four N poles 311 and four S poles 312 are formed in the ring magnet 31.

  The magnet collection rings 51 and 52 are disposed at positions (here, downward) offset from the ring magnet 31 in the axial direction (rotational axis direction). The magnet collection rings 51, 52 have a first magnet collection ring 51 and a second magnet collection ring 52 disposed above the first magnet collection ring 51, and both magnet collection rings 51, 52 Further, a ring magnet 31 is disposed above. Both magnetic flux collecting rings 51 and 52 are provided separately from both rotating members 111 and 112 so as not to rotate with rotation of both rotating members 111 and 112, and fixed to a non-rotating member such as a column housing ing.

  The magnet collection rings 51 and 52 are formed in a cylindrical shape having a width in the axial direction larger than a thickness in the radial direction, and an annular portion 511 and 521 coaxially arranged with the ring magnet 31 and a periphery of the annular portions 511 and 521 It projects radially outward from the same position in the direction, and has opposing portions 513 and 523 provided to axially face each other.

  Here, the connecting portion 512 is integrally provided to extend upward from the upper end portion of the annular portion 511 of the first magnetism collecting ring 51, and the opposing portion 513 is configured to protrude radially outward from the connecting portion 512. It is provided integrally. Further, in the second magnetism collecting ring 52, the connecting portion 522 is integrally provided so as to extend downward from the lower end portion of the annular portion 521, and the opposing portion 523 is protruded radially outward from the connecting portion 522. It is provided integrally. The two opposing portions 513 and 523 are provided to axially face each other at a predetermined interval, and the first magnetic detection element 61 as a magnetic detection element for detecting torque is disposed between the two opposing portions 513 and 523. 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 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 magnet collection ring 51, and the second magnetic yoke 42 magnetically couples the ring magnet 31 and the second magnet collection 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 unit 412 for transferring magnetic flux between the transfer unit 413 and the transfer unit 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 portion 413 is formed in a plate shape that radially faces the inner circumferential surface 511 a of the annular portion 511 of the first magnetism collecting ring 51.

  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 unit 422 for transferring a magnetic flux between the transfer unit 423 and the transfer unit 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 delivery portion 423 is formed in a plate shape that radially faces the inner peripheral surface 521 a of the annular portion 521 of the second magnetism collecting ring 52.

  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 strength 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 facing positions of the facing 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 displaced in the circumferential direction of the ring magnet 31.

  For example, when the ring magnet 31 rotates a predetermined angle (for example, 5 °) in the direction of arrow A in FIG. 3A with respect to the first and second magnetic yokes 41 and 42, the opposing piece 411 of the first magnetic yoke 41 and the axial direction Of the magnetic poles of the ring magnet 31 facing each other, the ratio occupied by the N pole 311 is higher than that of the S pole 312. Further, of the magnetic poles of the ring magnet 31 axially opposed to the facing piece 421 of the second magnetic yoke 42, the ratio occupied by the S pole 312 is higher than that of the N pole 311. As a result, part of the magnetic flux emitted from the N pole 311 passes through the first magnetic yoke 41 and the first magnetic flux collecting ring 51 and passes through the first magnetic detection element 61, 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 axially opposed to the facing piece 411 of the first magnetic yoke 41 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. Is higher than the S pole 312. Thereby, the magnetic flux passes through the first magnetic detection element 61 in the opposite direction 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 strength of the magnetic field detected by the first magnetic detection element 61 is changed, and the direction of the magnetic field is switched according to the twisting direction of the torsion bar.

  The torque and steering angle calculation unit 21 calculates a reactor angle which is a relative angle between the ring magnet 31 and the magnetic path forming member (magnetic yokes 41 and 42) based on the strength of the magnetic field detected by the first magnetic detection element 61. The steering torque of the steering wheel 10 is calculated based on the calculated reactor angle.

  Further, in the present embodiment, the shield member 63 is provided so as to cover the first magnetic detection element 61 and the both facing 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 not only a component of the torque detector 2a but also a component of the steering angle detector 2b.

  The second magnetic detection element 62 is disposed on a non-rotation member that does not rotate due to the rotation of the first rotation member 111 so as to face the outer circumferential surface of the ring magnet 31. As the second magnetic detection element 62, the radial direction (X direction) of the ring magnet 31, the axial direction (Y direction) parallel to the rotation axis O, and the 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 between the second magnetic detection element 62 and the ring magnet 31 (distance along the radial direction) is, for example, 15 mm.

  The second magnetic detection element 62 can detect the magnetic field received from the ring magnet 31 by being able to detect the magnetic field in the X direction and the Z direction. In addition, the second magnetic detection element 62 can detect the magnetic field in the Y direction parallel to the rotation axis O, so that the intensity of the magnetic field received from the slide magnet 32 can be detected.

  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 disposed to face the second magnetic detection element 62 in the axial direction (Y direction). The magnetization direction of the slide magnet 32 is 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). Accordingly, 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 disposed such that the N pole 321 faces the second magnetic detection element 62.

  The slide magnet 32 and the second magnetic detection element 62 are disposed between the first magnetic detection element 61 so as to sandwich the rotation axis O. Thus, the magnetic field of the slide magnet 32 is prevented from affecting 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) with the rotation of the first rotation member 111. The slide mechanism 7 includes a slider 71 as a support member for supporting the slide magnet 32, and a slide as an annular member in which an engaging portion 700 which rotates with the first rotating member 111 and meshes with the slider 71 on the outer peripheral surface is formed in a spiral shape. Drive member 70. Although not shown, the slide mechanism 7 may have a guide member fixed to a non-rotating member such as a column housing and guiding the slider 71 parallel to the rotation axis O. The slide driving member 70 and the slider 71 are made of, for example, a nonmagnetic metal such as aluminum or austenitic stainless steel or a nonmagnetic material such as 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. A ring magnet 31 is fixed to the lower end portion of the slide drive member 70, for example, by adhesion. The slide drive member 70 is formed such that the outer diameter of its lower end portion is smaller than the outer diameter of the engagement portion 700, and the ring magnet 31 is fitted to 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 driving member 70. The meshing portion 700 moves the slide magnet 32 in a direction to move the slide magnet 32 closer to or away from the second magnetic detection element 62 by meshing with the slider 71 even when the steering wheel 10 is steered to the left and right maximum steering angles. 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 provided so as to project outward and supporting the slide magnet 32. When the slide driving member 70 rotates with the first rotating member 111, the slider 71 moves up and down by the meshing of the meshing portion 700 and the slider side meshing portion.

  In the steering angle detection unit 2b, when the slide magnet 32 supported by the slider 71 moves downward with the slider 71, the distance between the slide magnet 32 and the second magnetic detection element 62 becomes short, and detection 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 with the slider 71, the distance between the slide magnet 32 and the second magnetic detection element 62 becomes longer, and the strength of the magnetic field in the Y direction detected by the second magnetic detection element 62 becomes weaker. .

  On the other hand, since the second magnetic detection element 62 is disposed 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 in the second direction. 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 N pole 311 and S pole 312 are provided in the ring magnet 31, the change period of the magnetic field strength in the X direction and the Z direction is 90 ° (± 45 °).

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

(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 suppress influence on the detection result.

  The shield member 63 is formed in a tubular shape having an opening in the radial direction of the annular portions 511 and 521 of the magnetic flux collection rings 51 and 52, and collects the magnetic flux so as to cover the first magnetic detection element 61 and both opposing portions 513 and 523. The magnetic rings 51 and 52 are spaced apart from each other.

  As the shield member 63, one made of a ferromagnetic material can be used, and for example, one made of a soft magnetic material such as iron or permalloy can be used. In the present embodiment, the 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, for example, in a cylindrical shape. The shield member 63 is formed of, for example, a magnet collection ring 51 or 52 by a support member (not shown) made of a nonmagnetic material such as aluminum or non-magnetic metal such as austenitic stainless steel or a nonmagnetic material such as hard resin. Supported and fixed.

  In the present embodiment, the shield member 63 is provided so as not to protrude radially outward of the first magnetic detection element 61. As a result of examination by the present inventors, if the shield member 63 is provided so as to project 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. It is because I found out that

  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. The length along the radial direction of the shield member 63 (in the case where the distance D between the base end surface which is the end surface on the side of the annular portion 511 and 521 of 63) and the rotation axis O (hereinafter referred to as end surface distance) is 19.4 mm Hereinafter, a simulation result of the influence of the external magnetic field noise when the length Ls of the shield member 63 is simply changed is shown in FIG. 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 (here mainly the influence by the ring magnet 31), and the horizontal axis represents the rotation angle of the ring magnet 31 (ring Angle).

  When the end face distance D is 19.4 mm, the distance d along the radial direction of the base end face of the shield member 63 and the annular portions 511 and 521 is 1.5 mm. Further, the projection length (length along the radial direction) of the facing portions 513 and 523 and the first magnetic detection element 61 from the annular portion 511 and 521 is 2 mm, and the length Ls of the shield member 63 is 2.5 mm. When it is large, it indicates that the shield member 63 protrudes radially outward more than the first magnetic detection element 61.

  Further, FIG. 5 shows a relationship between an angle error obtained by converting the magnetic flux density detected by the first magnetic detection element 61 into a reluctor angle due to the influence of the external magnetic field and the length Ls of the shield member 63. 4 and 5 also show simulation results in the case where the shield member 63 is not provided (without the shield).

  As shown in FIGS. 4 and 5, it can be seen that as the length Ls of the shield member 63 is increased, the influence of the external magnetic field noise (here, the influence by the ring magnet 31) increases and the angle error also increases. . Further, as shown in FIGS. 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 radially outward from the first magnetic detection element 61, whereby an external magnetic field is generated. 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 large and the angle error is also large as compared with the case where the shield member 63 is provided.

  In each case in which the length Ls of the shield member 63 is 8 mm and 0.5 mm, the direction of the magnetic flux obtained by the magnetic flux analysis is schematically shown in FIGS. 6 and 7.

  As shown in FIG. 6, when the shield member 63 has a length Ls of 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 is discharged to the inside (hollow part) of the shield member 63. Among the components, the magnetic flux emitted from the shield member 63 to the inside of the shield member 63 in the radially outward direction of the first magnetic detection element 61 is directed to the first magnetic detection element 61. Thus, 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 radially outward 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 toward the first magnetic detection element 61 is reduced, and the influence of the 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 shortening 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 both opposing portions 513 and 523 in the radial direction, external magnetic field noise It is possible to further suppress the influence. In other words, the length Ls of the shield member 63 is made shorter than the radial length of the first magnetic detection element 61 and the two opposing parts 513 and 523, and the length of the first magnetic detection element 61 and the two opposing parts 513 and 523 is Compared with the case where the first magnetic detection element 61 and both opposing portions 513 and 523 are entirely covered with the shield member 63, a part of the structure is exposed (projected) from the shield member 63. The influence can be further suppressed.

  In addition, the first magnetic detection element 61 and the both facing portions 513 and 523 are configured to project radially outward from the shield member 63, whereby the shield member 63 is released to the inside of the shield member 63. The magnetic flux directed to 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) For each case, the amplitude of the magnetic flux density detected by the first magnetic detection element 61 was determined by simulation due to the influence of external magnetic field noise when the length Ls of the shield member 63 was changed. 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 the end face distance D is 19.9 mm. The influence of external magnetic field noise can be minimized by setting Ls = 0.3 mm.

  According to the simulation result of FIG. 8, the influence of external magnetic field noise can be obtained by shortening the length Ls of the shield member 63 as the end face distance D increases (as the shield member 63 is disposed farther from the annular portions 511 and 521). It turns out that it becomes possible to suppress more. That is, external magnetic field noise can be obtained by appropriately selecting the length Ls of the shield member 63 in accordance with 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 portion 511, 521). Can be minimized.

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

(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. It is provided so that it does not protrude to.

  By providing the shield member 63, it is possible to suppress that the magnetic flux generated from the magnetic flux generation source such as the ring magnet 31 or the external device affects the first magnetic detection element 61. Further, by providing the shield member 63 so as not to project radially outward more than the first magnetic detection element 61, the magnetic flux emitted from the shield member 63 is prevented from passing through the first magnetic detection element 61. it can. As a result, it becomes possible to suppress the influence of external magnetic field noise and to measure torque accurately.

  Further, 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 steering angle detection unit 2b is configured by including the shield member 63. It is also possible to suppress that the members such as the slide magnet 32 and the like adversely affect the torque measurement.

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

(Summary of the embodiment)
Next, technical ideas to be understood from the embodiments described above will be described by using the reference numerals and the like in the embodiments. However, each reference numeral or the like in the following description does not limit the constituent elements in the claims to the members or the like specifically shown in the embodiments.

[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 such that the positional relationship between the magnetic poles (311, 312) changes and the transmitted magnetic flux changes according to the torsion of the torsion bar; Torque capable of detecting strength of magnetic field between a pair of magnetic flux collecting rings (51, 52) for collecting magnetic flux 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 magnetic flux collecting rings (51, 52) are formed into an annular portion (511.521) coaxially disposed with the ring magnet (31), and the annular portion (511, 521). And the opposing portions (513, 523) provided radially outward from the same position in the circumferential direction and facing in the axial direction, and the torque detection magnetic detection element (61) The torque is disposed between the two opposing portions (513, 523), is formed of a ferromagnetic material, and is formed in a tubular 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 a part of the torque detection magnetic detection element (61) and the both facing portions (513, 523) in the radial direction. The torque sensor (2) as described in 1].

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

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

  While the embodiments of the present invention have been described above, the embodiments described above do not limit the invention according to the claims. In addition, it should be noted that not all 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, although the torque steering angle sensor 2 including the torque detection unit 2a and the steering angle detection unit 2b has been described in the above embodiment, the steering angle detection unit 2b is omitted and only torque measurement is possible. It is also good.

111 ... first rotating member 112 ... second rotating member 2 ... torque steering angle sensor (torque sensor)
31 ... ring magnet 311 ... N pole (magnetic pole)
312 ... S pole (magnetic pole)
41 First magnetic yoke (magnetic path forming member)
42 Second magnetic yoke (magnetic path forming member)
51 ... 1st magnetic flux collecting ring (magnetic flux collecting ring)
52: Second magnetic flux collecting ring (magnetic flux collecting ring)
511, 521 ... annular portions 513, 523 ... facing portions 61 ... first magnetic detection element (magnetic detection element for torque detection)
63 ... Shield member

Claims (3)

A torque sensor disposed at a connecting portion of a first rotating member and a second rotating member connected by a torsion bar, the torque sensor comprising:
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 pole changes and the transmitted magnetic flux changes according to the torsion of the torsion bar;
A pair of magnetic flux collecting rings for collecting magnetic fluxes of the plurality of magnetic path forming members;
A magnetic detection element for detecting torque capable of detecting the strength of a magnetic field between the pair of magnet collection rings;
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 detection element capable of detecting the strength of the magnetic field in three tangential directions perpendicular to the first direction;
A slide magnet disposed opposite to the second magnetic detection element in the axial direction;
A slide mechanism for moving the slide magnet in the axial direction according to the rotation of the first rotation member;
Equipped with
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. Have a department, and
The torque detection magnetic detection element is disposed between the two facing parts,
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. With a shield member placed,
The shield member is provided so as not to project radially outward more than the torque detection magnetic detection element.
Torque sensor. The shield member is configured to cover only a part of the torque detection magnetic detection element and the two opposing portions in the radial direction.
The torque sensor according to claim 1. The torque detection magnetic detection element and the both facing portions are configured to protrude radially outward from the shield member.
The torque sensor according to claim 2.

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