JP2018179841A - Torque detector and ring magnet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a toque detector and a ring magnet with which it is possible to suppress the influence of a disturbance magnetic flux owing to its good sensitivity.SOLUTION: The torque detector comprises: a ring magnet 31, with a plurality of magnetic poles formed in the circumferential direction, that rotates together with a first rotary member 111; magnetic yokes 41, 42 provided so as to rotate together with a second rotary member 112 and constituted in such a way that a relative angle to the ring magnet 31 changes in accordance with the torsion of a torsion bar and the physical relation with the magnetic poles changes, so does the transferred magnetic flux, in accordance with a relative change of angle; and a first magnetism detection element 61 capable of detecting a change of magnetic flux guided by the magnetic yokes 41, 42. The ring magnet 31 includes a hollow cylindrical large diameter part 33 and a small diameter part 34 smaller in outside diameter than the large diameter part 33 and having an outer circumferential surface 34a formed so as to cross a surface perpendicular to the axial direction, and the magnetic yokes 41, 42 respectively include opposing parts 411, 421 facing the outer circumferential surface 34a of the small diameter part 34.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a torque detection device and a ring magnet.

  Conventionally, a torque detection device capable of detecting a steering torque is provided in an electric power steering device of a vehicle. As such a torque detection device, a torque steering angle sensor capable of detecting a steering angle in addition to a steering torque is known.

  The torque steering angle sensor is configured to detect a steering torque by detecting a twist angle of a torsion bar connecting an input shaft and an output shaft of a steering shaft. As such a torque steering angle sensor, an annular ring magnet having a plurality of magnetic poles of different polarities formed along the circumferential direction is provided on the input shaft, and relative to the ring magnet according to the torsion of the torsion bar on the output shaft. Provided with a magnetic path forming member configured to change the relative angle, change the positional relationship with the magnetic pole, and change the transmitted magnetic flux, and There is one that detects a torsion angle of a torsion bar, that is, a steering torque by detecting a change in magnetic flux with a magnetic detection element.

  Further, in the torque steering angle sensor, the steering angle is detected by detecting the rotation angle of the input shaft or the output shaft. For example, the magnetic detection element can be disposed to face the ring magnet of the input shaft, and the steering angle can be detected based on the strength of the magnetic field detected by the magnetic detection element.

  In the torque steering angle sensor, since a magnetic detection element for steering angle detection is provided to face the ring magnet in the radial direction, the magnetic path forming member is radially outward of the ring magnet (ring magnet and magnetic for steering angle detection If disposed between the detection elements), the detection accuracy of the steering angle may be reduced. Therefore, it is general to provide a magnetic path forming member so as to face the end surface (lower surface) in the axial direction of the ring magnet.

JP, 2016-99146, A

  By the way, in the ring magnet, a plurality of coils are arranged at equal intervals in the circumferential direction on the outer side in the radial direction of the annular base material to be the ring magnet, and the base material is magnetized by the magnetic field generated by the coils. Manufactured by Therefore, at the N pole of the ring magnet, the density of the magnetic flux directed radially outward increases, and the density of the magnetic flux directed axially decreases.

  Therefore, in the related art in which the magnetic path forming member is provided to face the end face in the axial direction of the ring magnet, the amount of change in the magnetic flux density detected by the magnetic detection element for torque detection with respect to the change in torsion angle of the torsion bar is It becomes smaller and sufficient sensitivity can not be obtained, and the error of the torque measurement value due to the influence of the disturbance magnetic flux (magnetic flux penetrating from the outside) also becomes large.

  Then, an object of the present invention is to provide a torque detection device and a ring magnet which have high sensitivity and can suppress the influence of disturbance magnetic flux.

  In order to solve the above-mentioned subject, the present invention is arranged in the connection part of the 1st rotation member connected by the torsion bar, and the 2nd rotation member, and the rotation axis of the 1st rotation member and the 2nd rotation member A plurality of magnetic poles of different polarities are formed along a circumferential direction centering on the ring, and an annular ring magnet that rotates with the first rotating member and a second rotating member are provided to rotate with the second rotating member. The plurality of coils are configured such that the relative angle with the ring magnet changes according to the twist, and the positional relationship with the magnetic pole changes and the transmitted magnetic flux changes with the relative angle change. A magnetic path forming member, and a magnetic detection element capable of detecting a change in magnetic flux led by the plurality of magnetic path forming members, wherein the ring magnet has a hollow cylindrical large diameter portion, and the large diameter portion Axial end of the And a small diameter portion having an outer peripheral surface smaller than the large diameter portion and formed so as to intersect a plane perpendicular to the axial direction. A magnetic path formation member provides a torque detection device which has an opposing part which counters an peripheral face of the above-mentioned small diameter part, respectively.

  In addition, the present invention is used for a torque detection device 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. A plurality of magnetic poles of different polarities are formed along a circumferential direction about the rotation axis of the second rotating member, and the ring magnet is a ring magnet that rotates with the first rotating member, wherein the large diameter of the hollow cylindrical shape A small diameter portion having an outer peripheral surface provided at the end in the axial direction of the large diameter portion and having an outer diameter smaller than the large diameter portion and intersecting a surface perpendicular to the axial direction And providing a ring magnet integrally.

  According to the present invention, it is possible to provide a torque detection device and a ring magnet which have high sensitivity and can suppress the influence of disturbance magnetic flux.

BRIEF DESCRIPTION OF THE DRAWINGS It is a schematic diagram which shows the electric-power-steering apparatus with which the torque steering angle sensor as a torque detection apparatus which concerns on one embodiment of this invention was applied. It is a side view of a torque steering angle sensor. FIG. 3 is a cross-sectional view of a torque detection unit in the torque steering angle sensor of FIG. 2; It is a figure which shows a ring magnet, (a) is the top view seen from the axial direction, (b) is the sectional view on the AA line. It is a figure which shows the jig | tool used for manufacture of a ring magnet, (a) is a top view, (b) is the BB sectional view taken on the line. It is a figure explaining the effect of the embodiment of the present invention, (a) is an explanatory view explaining the magnetic flux led from the ring magnet to the reluctor, (b) is a graph showing the relationship of the magnetic flux density to the reluctor angle. is there. It is a figure which shows the comparative example used as the comparison object of this invention, (a) is explanatory drawing explaining the magnetic flux guide | induced from a ring magnet to a relaxor, (b) is a graph which shows the relationship of the magnetic flux density to a relaxor angle. . It is a figure which shows other embodiment of this invention, (a) is sectional drawing of a torque detection part, (b) is sectional drawing of a ring magnet. (A) is explanatory drawing explaining the magnetic flux introduce | transduced from the ring magnet in the form of FIG. 8 to a relaxor, (b) is a graph which shows the relationship of the magnetic flux density with respect to a relaxor angle.

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

(Description of electric steering device)
FIG. 1 is a schematic view showing an electric power steering apparatus 1 to which a torque steering angle sensor as a torque detection device according to the present embodiment is applied.

  The electric power steering apparatus 1 includes a steering shaft 11 coupled to a steering wheel 10, an intermediate shaft 13 coupled to the steering shaft 11 via a universal joint 12, and a universal joint 14 to the intermediate shaft 13. Steering according to the steering torque applied to the steering shaft 11 at the time of steering operation of the steering wheel 10, the rack shaft 16 having the pinion shaft 15 connected in series, 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 moving force in a linear direction by, for example, a ball screw mechanism. And is applied to the rack shaft 16 as a steering assist force. However, as the steering assist mechanism 17, a column assist type that is provided on a steering column that supports the steering shaft 11, reduces the rotational force of the electric motor 170 by, for example, a worm gear mechanism, and applies it to the steering shaft 11 as a steering assist force. 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 calculates a steering torque and a steering angle based on an output signal of the torque steering angle sensor 2, and a steering that should be given based on the calculation result of the torque and steering angle calculation unit 21. A steering assist force computing unit 22 that computes an assist force, and a motor drive circuit 23 that outputs a motor current according to the steering assist force computed by the steering assist force computation unit 22 and drives an electric motor 170 of the steering assist mechanism 17. And.

  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 skid prevention device (ESC: Electronic Stability Control) of a vehicle.

  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. For example, the torque steering angle sensor 2 may be disposed on the pinion shaft 15.

(Description of torque steering angle sensor 2)
Next, the configuration of the torque steering angle sensor 2 will be described. In the following, for convenience of explanation, the side of the steering wheel 10 in the axial direction of the steering shaft 11 is referred to as "upper", and the opposite side (the side of the intermediate shaft 13) is referred to as "lower". Alternatively, “below” does not limit the vertical direction in the use state of the electric power steering apparatus 1.

  FIG. 2 is a side view of the torque steering angle sensor. 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). In the figure). 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.

(Description of torque detection unit 2a)
First, the torque detection unit 2a will be described. FIG. 3 is a cross-sectional view of the torque detection unit 2a.

  As shown in FIGS. 2 and 3, the torque detection unit 2 a includes an annular ring magnet 31 that rotates with the first rotating member 111 and a plurality of magnetic path forming members (reluctors) that form magnetic paths of magnetic flux by the ring magnet 31. As a first magnetic yoke (first reluctor) 41 and a second magnetic yoke (second reluctor) 42, and a pair of magnetic flux collecting rings 51 and 52 for collecting the magnetic flux of the first magnetic yoke 41 and the second magnetic yoke 42; 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.

  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 detailed shape of the ring magnet 31 will be described later.

  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 A ring magnet 31 is disposed further 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 have annular portions 511 and 521 coaxially arranged with the ring magnet 31. In the first magnetism collecting ring 51, the connecting portion 512 is integrally provided so as to extend upward from the upper end portion of the annular portion 511, and the opposing piece 513 is integrally formed so as to protrude radially outward from the connecting portion 512. It is provided. 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 piece 523 is integrally formed so as to protrude radially outward from the connecting portion 522 It is provided. The two facing pieces 513 and 523 are provided so as to axially face each other at a predetermined interval, and the first magnetic detection element 61 for detecting torque is disposed between the two facing pieces 513 and 523.

  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 first magnetic detection element 61 is capable of detecting a change in magnetic flux led by the first magnetic yoke 41 and the second magnetic yoke 42 by detecting the strength of the magnetic field between the pair of magnetic flux collecting rings 51 and 52. It has become. The output signal of the first magnetic detection element 61 is output to the control device 20, and the torque / steering angle calculation unit 21 of the control device 20 calculates the steering torque based on the output signal of the first magnetic detection element 61. It will be.

  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. 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 configured to be coupled to.

  The first magnetic yoke 41 and the second magnetic yoke 42 as magnetic path forming members change their relative angles with the ring magnet 31 according to the torsion of the torsion bar, and the magnetic poles change with the relative angle change. The positional relationship with the components 311 and 312 changes so that the magnetic flux to be transmitted changes. Detailed shapes and the like of the first magnetic yoke 41 and the second magnetic yoke 42 will be described later.

(Description of ring magnet 31)
In the present embodiment, the ring magnet 31 is provided at the hollow cylindrical large diameter portion 33 and at one end of the large diameter portion 33 in the axial direction, and the hollow cylindrical small diameter portion is smaller in outer diameter than the large diameter portion 33 And 34 are integrated. The inner diameter of the small diameter portion 34 is equal to the inner diameter of the large diameter portion 33.

  The outer peripheral surface 34 a of the small diameter portion 34 is formed to intersect with a surface perpendicular to the axial direction. In the present embodiment, the outer peripheral surface of the small diameter portion 34 is formed along the axial direction and the circumferential direction. Further, the ring magnet 31 has a step portion 35 having a step surface 35 a perpendicular to the axial direction between the large diameter portion 33 and the small diameter portion 34.

  In the present embodiment, the axial length h 1 of the small diameter portion 34 is set to 1/3 of the axial length H of the entire ring magnet 31. If the ratio of the small diameter portion 34 in the ring magnet 31 is too large, the magnetic flux from the small diameter portion 34 may affect the second magnetic detection element 62 for detecting the steering angle described later, which may lower the detection accuracy of the steering angle. Therefore, it is desirable that the axial length h1 of the small diameter portion 34 be 1⁄2 or less of the axial length H of the entire ring magnet 31.

  Further, although the details will be described later, in the present embodiment, a magnetic path forming member is provided in a space between an imaginary surface obtained by extending the outer peripheral surface of the large diameter portion 33 axially downward and the outer peripheral surface 34 a of the small diameter portion 34. The facing portions 411 and 421 of the first magnetic yoke 41 and the second magnetic yoke 42 are disposed. Therefore, the difference w between the outer diameters of the large diameter portion 33 and the small diameter portion 34 takes into account the thickness of the first magnetic yoke 41 and the second magnetic yoke 42, and the like. It should be set to the extent that it can be accommodated in space.

  As shown in FIGS. 5A and 5B, the ring magnet 31 sets the base material 91 to be the ring magnet 31 in the jig 92 and applies a magnetic field to the base material 91 by eight coils 93. Manufactured by magnetizing. In FIG. 5A, the direction of the magnetic field generated by the coil 93 is indicated by a broken arrow.

  In the jig 92, a base material accommodation hole 92a for accommodating the base material 91 and eight coil accommodation holes 92b for accommodating the coils 93 are formed. The coil accommodation holes 92b are formed at equal intervals in the circumferential direction outward in the radial direction of the base material accommodation hole 92a. When the base material 91 is accommodated in the base material accommodation hole 92a and the coil 93 is accommodated in the coil accommodation hole 92b, eight coils 93 are arranged at equal intervals in the circumferential direction outward in the radial direction of the matrix 91 Become. In this state, when the current of the coil 93 flows and the base material 91 is magnetized by the magnetic field generated by the coil 93, the ring magnet 31 is obtained.

  In the present embodiment, as shown in FIG. 5B, in the state where the base material 91 is accommodated in the base material accommodation hole 92a and the coil 93 is accommodated in the coil accommodation hole 92b, The axial center position and the center position of the coil 93 are radially opposed. Thus, the axial center position of the large diameter portion 33 is set as the center position of the magnetization (the position where the density of the magnetic flux directed outward in the axial direction in the N pole 311 is the largest). As will be described later, the second magnetic detection element 62 for detecting the steering angle is disposed so as to radially face the central position of the magnetization. Thus, the axial direction (Z direction) component of the magnetic flux from the ring magnet 31 detected by the second magnetic detection element 62 can be reduced, and the detection accuracy of the magnetic detection element 62 can be improved. That is, even when the small diameter portion 34 is formed in the ring magnet 31, the symmetry in the axial direction of the magnetic field with respect to the second magnetic detection element 62 can be maintained, and the detection accuracy of the steering angle can be suppressed from decreasing. become.

(Description of the magnetic yokes 41 and 42)
As shown in FIG. 3, the first magnetic yoke 41 has a magnetic flux between the facing portion 411 facing in parallel to the outer peripheral surface 34 a of the small diameter portion 34 of the ring magnet 31 and the annular portion 511 of the first magnetism collecting ring 51. And a transmission portion 412 for transmitting a magnetic flux between the facing portion 411 and the delivery portion 413.

  The facing portion 411 is formed in a plate shape that radially faces the outer peripheral surface 34 a of the small diameter portion 34, and extends in the axial direction. Here, the distance d between the outer peripheral surface 34 a of the small diameter portion 34 and the facing portion 411 was set to 0.5 mm. In the present embodiment, there is further provided a step surface facing portion 414 extending radially outward from the upper end of the facing portion 411 and axially facing the step surface 35a.

  The transmitting portion 412 extends axially downward from the radially inner end of the first radial transmitting portion 412 a extending radially inward from the lower end of the facing portion 411 and the radial inner end of the first radial transmitting portion 412 a. An axially extending transmission portion 412b extending from the lower end of the axially transmitting portion 412b and a second radial transmission portion 412c connected to the delivery portion 413 and extending in the radial direction are formed in a substantially U-shape There is. 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, and extends in the axial direction.

  Similarly, the second magnetic yoke 42 transfers magnetic flux between the facing portion 421 facing in parallel to the outer peripheral surface 34 a of the small diameter portion 34 of the ring magnet 31 and the annular portion 521 of the second magnetic flux collecting ring 52. A portion 423 and a transmission portion 422 for transmitting a magnetic flux between the facing portion 421 and the delivery portion 423 are integrally provided.

  The facing portion 421 is formed in a plate shape that radially faces the outer peripheral surface 34 a of the small diameter portion 34 and extends in the axial direction. Here, the distance d between the outer peripheral surface 34 a of the small diameter portion 34 and the facing portion 421 was set to 0.5 mm. In the present embodiment, there is further provided a step surface facing portion 424 extending radially outward from the upper end of the facing portion 421 and axially facing the step surface 35a.

  The transmitting portion 422 is connected to an axial transmitting portion 422a which extends continuously from the lower end of the facing portion 411 and extends downward in the axial direction, and extends outward in a radial direction from the lower end of the axial transmitting portion 422a. And a radial direction transmitting portion 422b. The delivery portion 413 is formed in a plate shape that radially faces the inner circumferential surface 521 a of the annular portion 521 of the second magnetism collecting ring 52, and extends in the axial direction.

  As described above, in the present embodiment, the two magnetic yokes 41 and 42 respectively have the facing portions 411 and 421 facing the outer peripheral surface 34 a of the small diameter portion 34. The two magnetic yokes 41 and 42 are formed, for example, by bending a strip of metal plate.

  In the present embodiment, in the magnetic yokes 41 and 42, the end on the opposing portion 411, 421 side (here, the end of the step surface opposing portion 414, 424) is radially outward of the large diameter portion 33. It does not stand out. That is, in the present embodiment, in the space between the virtual surface obtained by extending the outer peripheral surface of the large diameter portion 33 in the axial direction and the outer peripheral surface 34 a of the small diameter portion 34, the opposing portions 411 of the two magnetic yokes 41 and 42 421 is arranged. In the present embodiment, the radial positions of the end surfaces of the step surface opposing portions 414 and 424 and the radial positions of the outer peripheral surface of the large diameter portion 33 substantially coincide with each other.

(Operation of torque detection unit 2a)
When the steering torque is not applied to the steering shaft 11, both magnetic yokes 41 and 42 have their central portions facing the boundary between the N pole 311 and the S pole 312 of the ring magnet 31. Provided in 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 rotate relative to each other by this twist, and the magnetic pole 311 of the ring magnet 31 , 312 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 C in FIG. 3A with respect to the first and second magnetic yokes 41 and 42, the opposing portion 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 portion 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 It returns to S pole 312 through 42.

  On the other hand, when the ring magnet 31 rotates in the direction opposite to the arrow C direction with respect to the first and second magnetic yokes 41 and 42, the ring magnet axially opposed to the facing portion 411 of the first magnetic yoke 41 Of the 31 magnetic poles, the ratio occupied by the S pole 312 is higher than that of the N pole 311, and the ratio occupied by the N pole 311 among the magnetic poles of the ring magnet 31 axially opposed to the facing portion 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 (magnetic flux density) of the magnetic field detected by the first magnetic detection element 61 is proportional to the amount of torsion 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 the reluctor angle). . Therefore, based on the strength of the magnetic field detected by the first magnetic detection element 61, the torque / steering angle calculation unit 21 of the control device 20 compares the ring magnet 31 with the magnetic path forming members (magnetic yokes 41, 42). The reactor angle which is a proper angle is determined, and the steering torque of the steering wheel 10 is calculated based on the determined reactor angle.

  As described above, in the ring magnet 31, the density of the magnetic flux directed radially outward from the N pole 311 is relatively large, and the density of the magnetic flux directed axially outward from the N pole 311 is relatively reduced. As shown in FIG. 6A, the magnetic yokes 41 and 42 are arranged to be larger than the ring magnet 31 (large diameter portion 33) by arranging the opposing portions 411 and 421 so as to face the outer peripheral surface 34a of the small diameter portion 34. It is possible to collect the magnetic fluxes directed radially outward from the small diameter portion 34 at the opposing portions 411 and 421 without being disposed radially outward. Therefore, according to the present embodiment, the magnetic flux density of the magnetic flux flowing from the ring magnet 31 into the magnetic yokes 41 and 42 is increased compared to the case where the facing portions 411 and 421 are opposed to the axial end face of the ring magnet 31. It is possible to increase the magnetic flux density detected by the first magnetic detection element 61. As a result, the amount of change in magnetic flux density detected by the first magnetic detection element 61 with respect to the change in reluctor angle (hereinafter referred to as the torque magnetic flux density change coefficient. The unit is [mT / °]) becomes large, and the torque detection sensitivity is While improving, it also becomes possible to reduce the error of the torque measurement value due to the influence of disturbance magnetic flux (magnetic flux entering from the outside).

  In the present embodiment, the simulation of the magnetic flux density detected by the first magnetic detection element 61 with respect to the relaxor angle was performed. The simulation results are shown in FIG. As shown in FIG. 6 (b), in the present embodiment, the torque magnetic flux density change coefficient (slope in the graph of FIG. 6 (b)) was 2.42 [mT / °].

  Here, for comparison, the end portion of the magnetic yoke 43 was made to face the end face in the axial direction of the ring magnet 31 using the cylindrical ring magnet 37 not having the small diameter portion 34 as shown in FIG. 7A. The simulation was similarly performed for the comparative example. The simulation result is shown in FIG. 7 (b). As shown in FIG. 7 (b), in the comparative example, the torque magnetic flux density change coefficient was 1.21 [mT / °]. As can be understood by comparing FIG. 6B and FIG. 7B, in the present embodiment, the torque magnetic flux density change coefficient is large as compared with the comparative example, and good sensitivity is obtained.

(Description of the steering angle detection unit 2b)
Returning to FIG. 2, the steering angle detection unit 2b will be described. The steering angle detection unit 2 b includes a ring magnet 31 and a second magnetism detection element 62 fixed to the substrate 82 at a position receiving the magnetic field from the ring magnet 31 and a ring magnet for the second magnetism detection element 62. The slide magnet 32 generates a magnetic field in a direction different from 31 and the slide mechanism 7 moves the slide magnet 32 in a direction toward and away from the second magnetic detection element 62 as the first rotating member 111 rotates. And have. 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 sensing 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 disposed so as to radially face the axial center position of the large diameter portion 33 of the ring magnet 31. Since the axial center position of the large diameter portion 33 is the center position of the magnetization, the second magnetic detection element 62 is disposed so as to face the axial center position of the large diameter portion 33 in the radial direction. It is possible to suppress the magnetic field of the Y direction component from being received from the ring magnet 31, and to improve the detection accuracy of the steering angle.

  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 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. And a 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 the possible range.

  The slider 71 has an annular ring portion 711 formed on the inner peripheral surface with a slider side engagement portion (not shown) engaged with the engagement portion 700 of the slide driving member 70, 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 strength 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 three directions detected by the second magnetic detection element 62, the torque / steering angle calculation unit 21 of the control device 20 determines the strengths of the magnetic fields in the X and Z directions within an arbitrary period. Of the relative rotation angle of the ring magnet 31 (hereinafter referred to as ring angle), and, from the strength of the magnetic field in the Y direction, what period 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.

(Operation and effect of the embodiment)
As described above, in the torque steering angle sensor 2 as the torque detection device according to the present embodiment, the ring magnet 31 is provided at the hollow cylindrical large diameter portion 33 and one end portion of the large diameter portion 33 in the axial direction. A plurality of magnetic paths integrally provided with a small diameter portion 34 having an outer peripheral surface 34a provided so as to have an outer diameter smaller than that of the large diameter portion 33 and formed so as to intersect a plane perpendicular to the axial direction; The magnetic yokes 41 and 42 as forming members respectively have facing portions 411 and 421 facing the outer peripheral surface 34 a of the small diameter portion 34.

  With this configuration, the magnetic yokes 41 and 42 may be ring magnets, for example, when the second magnetic detection element 62 for detecting the steering angle is disposed radially outward of the ring magnet 31, or when the installation space is narrow. Even in the case where it can not be disposed radially outward of 31, it is possible to increase the magnetic flux density of the magnetic flux flowing from the ring magnet 31 into the magnetic yokes 41 and 42 and to increase the torque magnetic flux density change coefficient. As a result, it becomes possible to improve the sensitivity of torque detection, and it is also possible to reduce the error of the torque measurement value due to the influence of the disturbance magnetic flux (magnetic flux penetrating from the outside), and it is possible to improve the torque detection accuracy.

(Other embodiments)
Next, another embodiment of the present invention will be described. FIG. 8 is a view showing another embodiment of the present invention, in which (a) is a cross-sectional view of the torque detector 2a, and (b) is a cross-sectional view of the ring magnet 31. As shown in FIG.

  In the torque detection unit 2 a shown in FIG. 8, the outer peripheral surface 34 a of the small diameter portion 34 of the ring magnet 31 is formed in a tapered shape in which the diameter decreases as the distance from the large diameter portion 33 increases. The outer peripheral surface 34a of the small diameter portion 34 is inclined with respect to a surface perpendicular to the axial direction.

  The inclination angle θ of the outer peripheral surface 34a with respect to the plane perpendicular to the axial direction takes into account the thickness of the ring magnet 31 and the axial length h2 of the small diameter portion 34 is 1/2 the axial length H of the entire ring magnet 31. It is determined as follows. If the axial length h2 of the small diameter portion 34 exceeds 1⁄2 of the axial length H of the entire ring magnet 31, the detection accuracy of the steering angle may be reduced due to the influence of the small diameter portion 34. If the inclination angle θ is too small, the radial components of the magnetic flux can not be collected sufficiently by the magnetic yokes 41 and 42. Therefore, the inclination angle θ is preferably at least 10 degrees or more.

  Further, in the torque detection unit 2a shown in FIG. 8, the facing portions 411 and 421 of the magnetic yokes 41 and 42 are formed to face in parallel to the outer peripheral surface 34a of the tapered small diameter portion 34. That is, the facing portions 411 and 421 of the magnetic yokes 41 and 42 are inclined at the same angle as the outer circumferential surface 34 a of the small diameter portion 34 with respect to the plane perpendicular to the axial direction.

  The first radial direction transmitting portion 412 a of the first magnetic yoke 41 is inclined with respect to a plane perpendicular to the axial direction so as to be continuous with the lower end portion (radially inner end portion) of the facing portion 411. Further, the second magnetic yoke 42 is inclined with respect to a plane perpendicular to the axial direction so as to be continuous with the lower end portion (radially inner end portion) of the opposing portion 421, and transmits the axial direction with the opposing portion 421 It further has a connecting portion 422c that connects the portion 422a.

  In the present embodiment, when viewed from the opposing direction of the outer circumferential surface 34 a and the facing portions 411 and 421, the end portion on the outer circumferential side of the outer circumferential surface 34 a coincides with the end portion of the facing portions 411 and 421. Therefore, due to the influence of the thickness of the magnetic yokes 41 and 42, a part of the magnetic yokes 41 and 42 protrudes radially outward from the large diameter portion 33. However, it is desirable that the projection length be as small as possible, and at least the surface on the ring magnet 31 side at the end of the magnetic yokes 41 and 42 on the facing portion 411 and 421 side protrudes radially outward from the large diameter portion 33 Not desirable.

  As shown in FIG. 9A, the tapered small diameter portion 34 is formed, and the magnetic yokes 41 and 42 are provided so as to face the outer peripheral surface 34a thereof. It becomes possible to collect the component of the magnetic flux directed radially outward from the N pole 311, and it is possible to increase the magnetic flux density of the magnetic flux flowing into the magnetic yokes 41 and 42 and to increase the torque magnetic flux density change coefficient. Become.

  A simulation of the magnetic flux density detected by the first magnetic detection element 61 with respect to the relaxor angle is shown in FIG. As shown in FIG. 9 (b), in this embodiment, the torque magnetic flux density change coefficient is 2.27 [mT / °]. As can be understood by comparing FIG. 9B and FIG. 7B, in the present embodiment, the torque magnetic flux density change coefficient is large as compared with the comparative example, and a good sensitivity is obtained.

(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] It is disposed at the connecting portion of the first rotating member (111) and the second rotating member (112) connected by the torsion bar, and the rotation of the first rotating member (111) and the second rotating member (111) A plurality of magnetic poles (311, 312) having different polarities are formed along a circumferential direction about the axis (O), and an annular ring magnet (31) that rotates with the first rotating member (111); It is provided to rotate together with the two rotation member (112), and the relative angle with the ring magnet (31) changes according to the torsion of the torsion bar, and the above-mentioned relative angle changes with the change of the relative angle A plurality of magnetic path forming members (41, 42) configured to change the positional relationship with the magnetic poles (311, 312) and change the transmitted magnetic flux, and the plurality of magnetic path forming members (41, 42) Led flux A magnetic detection element (61) capable of detecting a change, and the ring magnet (31) is provided at a hollow cylindrical large diameter portion (33) and one end of the large diameter portion (33) in the axial direction A small diameter portion (34) having an outer peripheral surface (34a) which is provided and whose outer diameter is smaller than that of the large diameter portion (33) and which is formed to intersect a plane perpendicular to the axial direction A torque detection device (wherein the plurality of magnetic path forming members (41, 42) respectively have opposing portions (411, 421) facing the outer peripheral surface (34a) of the small diameter portion (34) 1).

[2] The surface on the ring magnet (31) side at the end on the opposing part (411, 412) side of the magnetic path forming member (41, 42) is radially outward of the large diameter part (33) The torque detection device (1) according to [1], which does not protrude in the direction.

[3] In [2], the end of the magnetic path forming member (41, 42) on the side facing the opposing portion (411, 412) does not protrude radially outward from the large diameter portion (33) Torque detection device (1) as described.

[4] The outer peripheral surface (34a) of the small diameter portion (34) is formed along the axial direction, and the ring magnet (31) includes the large diameter portion (33) and the small diameter portion (34) The torque detection device (1) according to any one of [1] to [3], further comprising: a step portion (35) having a step surface (35a) perpendicular to the axial direction.

[5] Any one of [1] to [3], wherein the outer peripheral surface (34a) of the small diameter portion (34) is formed in a tapered shape in which the diameter decreases with distance from the large diameter portion (33). The torque detection apparatus (1) as described in a term.

[6] The torque detection device (1) according to [5], wherein the inclination angle of the outer peripheral surface (34a) of the small diameter portion (34) with respect to the plane perpendicular to the axial direction is 10 degrees or more.

[7] A magnet for detecting a steering angle, which is disposed on a non-rotating member that does not rotate due to the rotation of the first rotating member (111) so as to face the outer peripheral surface of the large diameter portion (33) of the ring magnet (31) The torque detection device (1) according to any one of [1] to [6], further comprising a detection element (62).

[8] A torque detection device (1) disposed at a connecting portion of a first rotating member (111) and a second rotating member (112) connected by a torsion bar, the first rotating member (111) and A plurality of magnetic poles (311, 312) having different polarities are formed along the circumferential direction around the rotation axis (O) of the second rotating member (112), and an annular ring rotates with the first rotating member (111) Ring magnet (31), provided at the hollow cylindrical large diameter portion (33) and at one end of the large diameter portion (33) in the axial direction, and the outer diameter is larger than that of the large diameter portion (33) A ring magnet (31) integrally having a small diameter portion (34) having an outer peripheral surface (34a) which is small and formed to intersect with a plane perpendicular to the axial direction.

[9] The outer peripheral surface (34a) of the small diameter portion (34) is formed along the axial direction, and the ring magnet (31) includes the large diameter portion (33) and the small diameter portion (34) The ring magnet (31) according to [8], further comprising: a stepped portion (35) having a stepped surface (35a) perpendicular to the axial direction.

[10] The ring magnet (31) according to [8], wherein the outer peripheral surface (34a) of the small diameter portion (34) is formed in a tapered shape which is reduced in diameter as it is separated from the large diameter portion (33). .

  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 combinations of features described in the embodiments are essential to the means for solving the problems of the invention. Further, the present invention can be appropriately modified and implemented without departing from the scope of the invention.

2 ... Torque steering angle sensor (torque detection device)
2a ... torque detection unit 2b ... steering angle detection unit 31 ... ring magnet 311 ... N pole (magnetic pole)
312 ... S pole (magnetic pole)
33 Large diameter portion 34 Small diameter portion 34a Outer circumferential surface 35 Stepped portion 35a Stepped surface 41 First magnetic yoke (magnetic path forming member)
411: Opposite portion 42: Second magnetic yoke (magnetic path forming member)
421: facing portion 51: first magnetic flux collecting ring 52: second magnetic flux collecting ring 61: first magnetic detection element (magnetic detection element)
62 second magnetic detection element 111 first rotary member 112 second rotary member O rotational axis

Claims (10)

Disposed at a connecting portion of the first rotating member and the second rotating member connected by the torsion bar,
A plurality of magnetic poles of different polarities are formed along a circumferential direction about the rotation axis of the first rotating member and the second rotating member, and an annular ring magnet that rotates with the first rotating member;
It is provided to rotate with the second rotating member, and the relative angle with the ring magnet changes according to the torsion of the torsion bar, and the position with the magnetic pole according to the relative angle change. A plurality of magnetic path forming members configured to change the relationship and change the transmitted magnetic flux;
And a magnetic detection element capable of detecting a change in magnetic flux led by the plurality of magnetic path forming members,
The ring magnet is provided at a hollow cylindrical large diameter portion and at one end of the large diameter portion in the axial direction, and has an outer diameter smaller than that of the large diameter portion and intersects a plane perpendicular to the axial direction A small diameter portion having an outer peripheral surface formed on the
Each of the plurality of magnetic path forming members has an opposing portion opposed to the outer peripheral surface of the small diameter portion.
Torque detection device. The surface on the ring magnet side at the end on the facing portion side of the magnetic path forming member does not protrude radially outward from the large diameter portion,
The torque detection device according to claim 1. An end of the magnetic path forming member on the opposite portion side does not protrude radially outward from the large diameter portion.
The torque detection device according to claim 2. An outer peripheral surface of the small diameter portion is formed along the axial direction,
The ring magnet has a stepped portion having a stepped surface perpendicular to the axial direction between the large diameter portion and the small diameter portion.
The torque detection device according to any one of claims 1 to 3. The outer peripheral surface of the small diameter portion is formed in a tapered shape in which the diameter decreases as the distance from the large diameter portion increases.
The torque detection device according to any one of claims 1 to 3. The inclination angle of the outer peripheral surface of the small diameter portion with respect to the surface perpendicular to the axial direction is 10 degrees or more.
The torque detection device according to claim 5. The non-rotating member that does not rotate due to the rotation of the first rotating member further includes a magnetic detection element for detecting a steering angle disposed opposite to the outer peripheral surface of the large diameter portion of the ring magnet.
The torque detection device according to any one of claims 1 to 6. It is used for a torque detection device disposed at a connecting portion of a first rotating member and a second rotating member connected by a torsion bar,
A plurality of magnetic poles having different polarities are formed along a circumferential direction about the rotation axis of the first and second rotary members, and the ring magnet is a ring magnet that rotates with the first rotary member.
A hollow cylindrical large diameter portion,
A small diameter portion provided at one end in the axial direction of the large diameter portion and having an outer peripheral surface smaller in outer diameter than the large diameter portion and formed to intersect a plane perpendicular to the axial direction; Have one,
Ring magnet. An outer peripheral surface of the small diameter portion is formed along the axial direction,
The ring magnet has a stepped portion having a stepped surface perpendicular to the axial direction between the large diameter portion and the small diameter portion.
A ring magnet according to claim 8. The outer peripheral surface of the small diameter portion is formed in a tapered shape in which the diameter decreases as the distance from the large diameter portion increases.
A ring magnet according to claim 8.

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