JP2014092452A - Torque detector and steering device with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque detector that is able to restrict occurrence of significant heat stress in a sensor housing, and to provide a steering device with the torque device.SOLUTION: The torque detector comprises: an annular collected magnet unit 50 having an annular collected magnet holder 60 made of non-magnetic resin, and a first and second collected magnet rings 51 and 54 held by the collected magnet holder 60; and a sensor housing 70 integrally formed with the collected magnet unit 50 from resin caused to flow on the peripheral side of the collected magnet unit 50. The sensor housing 70 is formed from magnetic resin formed from a resin material and ferrite powder as magnetic powder.

Description

  The present invention relates to a torque detection device having a magnetic flux collecting unit that collects magnetic flux from a magnetic yoke, and a steering device including the device.

  A conventional torque detector includes a magnetic flux collecting unit having a magnetic flux collecting ring, a ring holder, and a magnetic shield, and a sensor housing that holds the magnetic flux collecting unit. This torque detector has a configuration in which the magnetic flux collecting unit is fixed to the sensor housing in a state where the magnetic flux collecting unit is inserted into an insertion hole formed in the sensor housing. Patent Document 1 shows an example of a conventional torque detection device.

JP 2008-249598 A

  In the conventional torque detection device, water may enter the device from between the magnetism collecting unit and the housing. Therefore, in order to improve the waterproofness of the torque detection device, as shown in FIG. 8, the sensor housing 220 is formed integrally with the magnetic flux collecting unit 210 by pouring resin into the outer peripheral side of the magnetic flux collecting unit 210. A torque detection device 200 is conceivable.

  The magnetic flux collecting unit 210 includes a magnetic flux collecting holder 211, a magnetic flux collecting ring 212, and a magnetic shield 213. The magnetism collecting unit 210 has a configuration in which a magnetism collecting ring 212 is attached to the inner peripheral surface 211 </ b> X of the magnetism collecting holder 211 and a magnetic shield 213 is attached to the outer peripheral surface 211 </ b> Y of the magnetism collecting holder 211.

  The magnetic shield 213 is formed of a metal plate. The magnetic shield 213 has a C shape in plan view. The magnetic shield 213 contacts the outer peripheral surface 211Y of the magnetism collecting holder 211 on the inner peripheral surface 213X.

  The sensor housing 220 is in close contact with the magnetism collecting holder 211 and the magnetic shield 213. In the sensor housing 220, the inner surface 221 contacts the outer peripheral surface 213Y of the magnetic shield 213 and the corner portion 213B of the shield end 213A of the magnetic shield 213.

  In the torque detection device 200, the linear expansion coefficient of the sensor housing 220 is larger than the linear expansion coefficient of the magnetic shield 213. For this reason, the amount of thermal expansion of the sensor housing 220 accompanying the temperature change of the torque detection device 200 is larger than the amount of thermal expansion of the magnetic shield 213, and the amount of thermal contraction of the sensor housing 220 is larger than the amount of thermal contraction of the magnetic shield 213.

  For this reason, the corner portion 213 </ b> B of the shield end 213 </ b> A of the magnetic shield 213 is pressed against the inner surface 221 of the sensor housing 220 as the temperature of the torque detection device 200 changes. Therefore, a large thermal stress is generated in the sensor housing 220 as the temperature of the torque detection device 200 changes.

  In order to solve the above-described problems, an object of the present invention is to provide a torque detection device capable of suppressing the occurrence of a large thermal stress in a sensor housing, and a steering device including the device.

  The first means is “a permanent magnet, a magnetic yoke that is disposed in a magnetic field formed by the permanent magnet and changes its relative position with respect to the permanent magnet, and a ring formed of a non-magnetic resin to form the magnetic A magnetic flux collecting unit surrounding the yoke; and an annular magnetic flux collecting unit that is held on the inner peripheral side of the magnetic flux collecting holder and collects the magnetic flux of the magnetic yoke; the permanent magnet; the magnetic yoke; A magnetic sensor for detecting the magnetic flux of the magnetic circuit formed by the magnetic ring and a magnetic resin in which magnetic powder is added to a resin material are poured into the outer peripheral side of the magnetic flux collecting holder, thereby closely contacting the outer peripheral surface of the magnetic flux collecting holder. A torque detecting device including a sensor housing formed integrally with the magnetic flux collecting unit in the state of being.

  In the torque detection device, the sensor housing is in close contact with the outer peripheral surface of the magnetism collecting holder. That is, there is no magnetic shield between the magnetism collecting holder and the sensor housing. For this reason, it is avoided that thermal stress arises in a sensor housing resulting from the linear expansion coefficient of a sensor housing being larger than the linear expansion coefficient of a magnetic shield. In addition, since both the sensor housing and the magnetic flux collecting holder are resin-molded, the difference between the linear expansion coefficient of the sensor housing and the linear expansion coefficient of the magnetic flux collecting holder is the difference between the linear expansion coefficient of the sensor housing and the linear expansion coefficient of the magnetic shield. Smaller than the difference. Therefore, it is possible to suppress a large thermal stress from being generated in the sensor housing due to a temperature change of the torque detection device.

  The second means is: “a permanent magnet, a magnetic yoke disposed in a magnetic field formed by the permanent magnet and changing a relative position with the permanent magnet, and a ring formed of a nonmagnetic resin to form the magnetic A magnetic flux collecting unit surrounding the yoke; and an annular magnetic flux collecting unit that is held on the inner peripheral side of the magnetic flux collecting holder and collects the magnetic flux of the magnetic yoke; the permanent magnet; the magnetic yoke; A magnetic sensor for detecting the magnetic flux of the magnetic circuit formed by the magnetic ring and a magnetic resin in which magnetic powder is added to a resin material are poured into the outer peripheral side of the magnetic flux collecting holder, thereby closely contacting the outer peripheral surface of the magnetic flux collecting holder. A cover part molded integrally with the magnetism collecting unit in a state where the cover part is formed, and a sensor housing molded integrally with the cover part by a resin poured into the outer peripheral side of the cover part. Having obtain torque detector ".

  In the torque detection device, the cover component is in close contact with the outer peripheral surface of the magnetism collecting holder. That is, there is no magnetic shield between the magnetism collecting holder and the sensor housing (cover component). For this reason, it is avoided that thermal stress arises in a sensor housing resulting from the linear expansion coefficient of a sensor housing being larger than the linear expansion coefficient of a magnetic shield. In addition, since both the sensor housing and the magnetic flux collecting holder are resin-molded, the difference between the linear expansion coefficient of the sensor housing and the linear expansion coefficient of the magnetic flux collecting holder is the difference between the linear expansion coefficient of the sensor housing and the linear expansion coefficient of the magnetic shield. Smaller than the difference. Therefore, it is possible to suppress a large thermal stress from being generated in the sensor housing due to a temperature change of the torque detection device.

  One form of the above means is that “the magnetic flux collecting holder includes an annular holder main body surrounding the magnetic yoke and a holding portion that protrudes outward from the holder main body, and the magnetic flux collecting ring includes the holder It has a magnetic flux collection protrusion that protrudes outward from the main body and faces the magnetic sensor, and the magnetic flux collection protrusion has a torque detection device accommodated in the holding portion.

  In the torque detection device, since the magnetic flux collection protrusion is accommodated in the holding portion, the contact between the sensor housing and the magnetic flux collection protrusion is suppressed. For this reason, it is suppressed that the magnetic flux between a magnetic flux collection protrusion and a magnetic sensor flows into a sensor housing. Therefore, a decrease in detection accuracy of the magnetic flux density of the magnetic sensor is suppressed.

  One mode of the above means includes a “steering device including the torque detection device”.

  The present invention can suppress the occurrence of a large thermal stress in the sensor housing.

The block diagram which shows the structure of the steering device of embodiment. The perspective view which shows the disassembled perspective structure of the torque detection apparatus of embodiment. Sectional drawing which shows the cross-section of the torque detection apparatus of embodiment. The perspective view which shows the perspective structure of the magnetic flux collecting unit of embodiment. FIG. 3 is a development view showing a positional relationship between a permanent magnet, each magnetic yoke, and each magnetism collecting ring in the torque detection device of the embodiment. It is a perspective view of a sensor unit of other embodiments, (a) is a perspective view showing a perspective structure of a sensor unit, (b) is a perspective view showing an enlarged structure of a field surrounded by a dashed line. It is sectional drawing of the sensor unit of other embodiment, (a) is sectional drawing which shows the sectional structure of the plane parallel to radial direction, (b) is sectional drawing which shows the sectional structure of Z7-Z7 plane of (a) . Sectional drawing which shows the cross-section of a part of the torque detection apparatus of a comparative example.

The configuration of the steering device 1 will be described with reference to FIG.
The steering device 1 includes a steering device body 10, an assist device 20, and a torque detection device 30. The steering device 1 has a configuration as a dual pinion assist type electric power steering device in which the assist device 20 assists the operation of the steering wheel 2.

  The steering device body 10 includes a column shaft 11, an intermediate shaft 12, a pinion shaft 13, a rack shaft 14, a rack and pinion mechanism 15, two tie rods 16, and a rack housing 17. The steering device body 10 integrally rotates the column shaft 11, the intermediate shaft 12, and the pinion shaft 13 as the steering wheel 2 rotates. The steering device body 10 reciprocates the rack shaft 14 in the longitudinal direction by the rotation of the pinion shaft 13. The steering device body 10 changes the turning angle of the steered wheels 3 by reciprocating the rack shaft 14.

  The pinion shaft 13 includes a first shaft 13A, a second shaft 13B, and a torsion bar 13D. The pinion shaft 13 has a configuration in which a torsion bar 13D connects the first shaft 13A and the second shaft 13B.

The first shaft 13 </ b> A is connected to the intermediate shaft 12. The first shaft 13 </ b> A rotates integrally with the intermediate shaft 12.
The second shaft 13B has a pinion gear 13C. The second shaft 13B meshes with the first rack gear 14A of the rack shaft 14 in the pinion gear 13C.

  The rack shaft 14 has a first rack gear 14A and a second rack gear 14B. The first rack gear 14 </ b> A has a plurality of rack teeth formed over a predetermined range in the longitudinal direction of the rack shaft 14. The second rack gear 14 </ b> B is formed in a portion separated from the first rack gear 14 </ b> A in the longitudinal direction of the rack shaft 14. The second rack gear 14 </ b> B has a plurality of rack teeth formed over a predetermined range in the longitudinal direction of the rack shaft 14.

  The rack and pinion mechanism 15 includes a pinion gear 13 </ b> C of the pinion shaft 13 and a first rack gear 14 </ b> A of the rack shaft 14. The rack and pinion mechanism 15 converts the rotation of the pinion shaft 13 into the reciprocating motion of the rack shaft 14.

  The rack housing 17 has a cylindrical shape corresponding to the shape of the rack shaft 14. The rack housing 17 accommodates a part of the pinion shaft 13, the rack shaft 14, and the tie rod 16 in the internal space.

  The assist device 20 includes an assist motor 21, a worm shaft 22, a worm wheel 23, and a pinion shaft 24. The assist device 20 has the following connection configuration. That is, the output shaft of the assist motor 21 is connected to the worm shaft 22. The worm shaft 22 meshes with the worm wheel 23. The worm wheel 23 is fixed to the pinion shaft 24. The pinion gear 24A of the pinion shaft 24 meshes with the second rack gear 14B. The assist device 20 applies a force acting in the longitudinal direction of the rack shaft 14 to the rack shaft 14 by rotating the pinion shaft 24 while the assist motor 21 is decelerated via the worm shaft 22 and the worm wheel 23. .

  The torque detection device 30 is located around the pinion shaft 13. The torque detection device 30 is fixed to the fixed component 17 </ b> A of the rack housing 17. The torque detection device 30 detects the torque applied to the pinion shaft 13.

With reference to FIG. 2 and FIG. 3, the structure of the torque detection apparatus 30 is demonstrated. In FIG. 2, the sensor unit 40 in which the circuit unit 80 is omitted is shown.
Here, as the respective directions related to the torque detection device 30, “axial direction ZA”, “upward direction ZA1”, “downward direction ZA2”, “radial direction ZB”, “inward direction ZB1”, “outward direction ZB2”, and “ A circumferential direction ZC ”is defined.

The circumferential direction ZC indicates a direction around the rotation center axis of the pinion shaft 13 (see FIG. 3).
The axial direction ZA indicates a direction along the rotation center axis of the pinion shaft 13. The axial direction ZA is defined by an upward direction ZA1 and a downward direction ZA2 indicating directions opposite to each other. An upward direction ZA1 indicates a direction in which the second shaft 13B and the first shaft 13A (both refer to FIG. 3) pass in order. The downward direction ZA2 indicates a direction passing through the first shaft 13A and the second shaft 13B in this order.

  The radial direction ZB indicates a normal direction of the axial direction ZA. The radial direction ZB is defined by an inner direction ZB1 and an outer direction ZB2 indicating directions opposite to each other. The inward direction ZB1 indicates a direction approaching the rotation center axis of the pinion shaft 13. The outward direction ZB2 indicates a direction away from the rotation center axis of the pinion shaft 13.

  As shown in FIG. 2, the torque detection device 30 includes a sensor unit 40, a magnet unit 90, and a magnetic yoke unit 100. The torque detection device 30 has a configuration in which the magnet unit 90 and the magnetic yoke unit 100 are accommodated in the internal space 78 of the sensor unit 40.

  As shown in FIG. 3, in the torque detection device 30, a gap between the torque detection device 30 and the first shaft 13 </ b> A is sealed with an oil seal 31. In the torque detection device 30, a gap between the torque detection device 30 and the fixed component 17 </ b> A of the rack housing 17 is sealed by an O-ring 32.

  The magnet unit 90 is fixed to the first shaft 13A. The magnet unit 90 has a permanent magnet 91 and a core 92. The magnet unit 90 is configured as an assembly in which a permanent magnet 91 and a core 92 are coupled to each other.

  The permanent magnet 91 has a cylindrical shape. The permanent magnet 91 has an N pole and an S pole adjacent to each other in the circumferential direction ZC (see FIG. 2). The permanent magnet 91 forms a magnetic field around the first shaft 13A.

  The core 92 is fixed to the inner peripheral surface of the permanent magnet 91. The core 92 is press-fitted into the outer peripheral surface of the first shaft 13A. The core 92 prevents the magnetic flux of the permanent magnet 91 from leaking in the inward direction ZB1 from the core 92.

  The magnetic yoke unit 100 surrounds the magnet unit 90. The magnetic yoke unit 100 is fixed to the second shaft 13B. The magnetic yoke unit 100 includes a first magnetic yoke 101, a second magnetic yoke 102, a yoke holder 103, and an intermediate part 104.

  The yoke holder 103 is resin-molded integrally with the first magnetic yoke 101 and the second magnetic yoke 102. The yoke holder 103 has an annular shape. The yoke holder 103 is fixed to the second shaft 13B via the intermediate part 104.

  The first magnetic yoke 101 has an annular shape. The first magnetic yoke 101 is located in the upward direction ZA1 of the yoke holder 103. The first magnetic yoke 101 has a plurality of tooth portions 101A and a plurality of connection portions 101B (see FIG. 5). The first magnetic yoke 101 has a tapered shape in which the tooth portion 101A tapers as it goes in the downward direction ZA2 (see FIG. 5). The first magnetic yoke 101 has a configuration in which tooth portions 101A adjacent in the circumferential direction ZC are connected to each other by a connecting portion 101B (see FIG. 5). The first magnetic yoke 101 receives the magnetic flux of the permanent magnet 91. The first magnetic yoke 101 changes its position relative to the permanent magnet 91 as the torsion bar 13D is twisted.

  The second magnetic yoke 102 has an annular shape. The second magnetic yoke 102 is located at an intermediate portion of the yoke holder 103 in the axial direction ZA. The second magnetic yoke 102 has a plurality of tooth portions 102A and a plurality of connection portions 102B (see FIG. 5). The second magnetic yoke 102 has a tapered shape in which the tooth portion 102A tapers as it goes in the upward direction ZA1 (see FIG. 5). The second magnetic yoke 102 has a configuration in which adjacent tooth portions 102A in the circumferential direction ZC are connected to each other by a connection portion 102B (see FIG. 5). In the second magnetic yoke 102, the tooth portion 102A is located between the tooth portions 101A adjacent in the circumferential direction ZC (see FIG. 5). The second magnetic yoke 102 receives the magnetic flux of the permanent magnet 91. The relative position of the second magnetic yoke 102 with respect to the permanent magnet 91 changes as the torsion bar 13D is twisted.

  The sensor unit 40 is fixed to the fixed component 17A of the rack housing 17 by a first bolt (not shown). The sensor unit 40 includes a Hall IC as two magnetic sensors 41, a magnetism collecting unit 50, a sensor housing 70, and a circuit unit 80.

  The magnetic flux collecting unit 50 has an annular shape surrounding the magnet unit 90 and the magnetic yoke unit 100. The magnetic flux collecting unit 50 includes a first magnetic flux collecting ring 51, a second magnetic flux collecting ring 54, and a magnetic flux collecting holder 60. The magnetic flux collecting unit 50 collects the magnetic flux of the magnetic yoke unit 100 and flows the magnetic flux toward the magnetic sensor 41.

  The two magnetic sensors 41 are adjacent to each other in the circumferential direction ZC. The magnetic sensor 41 detects a magnetic flux of a magnetic circuit (hereinafter referred to as “magnetic circuit MC”) formed by the permanent magnet 91, the magnetic yokes 101 and 102, and the magnetic flux collecting rings 51 and 54. The magnetic sensor 41 outputs a voltage corresponding to the magnetic flux density of the magnetic circuit MC. The output voltage of the magnetic sensor 41 is transmitted to the control device (not shown) of the steering device 1 (see FIG. 1) via the circuit unit 80.

  The circuit unit 80 includes a circuit board 81 and a support component 82. The circuit board 81 is fixed to the inner surface of the support component 82. In the circuit board 81, two magnetic sensors 41 are connected.

  The sensor housing 70 is molded integrally with the magnetism collecting unit 50 by pouring molding resin into the outer peripheral side of the magnetism collecting unit 50. The sensor housing 70 uses a magnetic resin as a molding resin. The magnetic resin is formed by adding ferrite powder, which is magnetic powder, to a resin material. In the magnetic resin, the ratio of the weight of the ferrite powder to the total weight of the magnetic resin is set to a value such that the sensor housing 70 is not magnetically saturated by the external magnetic field of the torque detection device 30. The ratio of the weight of the ferrite powder to the total weight of the magnetic resin is set in advance by testing and simulation. The sensor housing 70 has a function of suppressing water from entering the sensor housing 70 and a function of reducing the influence of the external magnetic field of the torque detection device 30 on the magnetic circuit MC.

  The sensor housing 70 includes a housing main body 71, a board mounting portion 76 (see FIG. 2), and a device mounting portion 77 (see FIG. 2). The sensor housing 70 has a configuration in which a housing main body 71, a board mounting portion 76, and a device mounting portion 77 are integrally formed of the same material.

  The housing body 71 is formed in a cylindrical shape having an internal space 78 that penetrates the housing body 71 in the axial direction ZA. The housing main body 71 includes a base portion 72, a magnetism collecting housing portion 73, a magnetism collecting cover portion 74, and a side opening portion 75. The dimension of the housing body 71 in the axial direction ZA is larger than the dimension of the magnetic flux collecting unit 50 in the axial direction ZA.

  The base portion 72 is located in a lower direction ZA2 than the magnetism collecting housing portion 73 and the magnetism collecting cover portion 74. The base portion 72 is located in the lower direction ZA2 than the magnetic flux collecting unit 50. The base portion 72 surrounds the fixed component 17A in a state where the lower end portion is in contact with the fixed component 17A of the rack housing 17.

  The magnetic flux collecting portion 73 accommodates the magnetic flux collecting unit 50, the magnet unit 90, and the magnetic yoke unit 100. The magnetism collecting portion 73 holds the magnetism collecting unit 50 in a state where the inner surface 71X is in close contact with the outer peripheral surface 60Y of the magnetism collecting holder 60.

  The magnetism collecting cover portion 74 is positioned in the upward direction ZA1 with respect to the magnetism collecting housing portion 73 (magnetism collecting unit 50). The magnetism collecting cover portion 74 includes an inclined portion 74A that inclines in the inward direction ZB1 from the upper end portion of the magnetism collecting housing portion 73 in the upward direction ZA1, and a cylindrical portion 74B that extends in the upward direction ZA1 from the inclined portion 74A. The magnetism collecting cover portion 74 covers the magnetism collecting unit 50 from the upward direction ZA1 at the inclined portion 74A. The magnetic seal cover portion 74 is attached with the oil seal 31 at the cylindrical portion 74B.

  The side surface opening portion 75 penetrates the magnetic flux collecting portion 73 in the radial direction ZB in a part of the circumferential direction ZC of the magnetic flux collecting portion 73. In the side opening portion 75, the holding portion 62 of the magnetism collecting holder 60 is inserted.

  As shown in FIG. 2, the board mounting portions 76 are located on both sides of the side opening portion 75 in the plan view of the sensor housing 70. The board attachment portion 76 has an insertion hole into which a second bolt (not shown) is inserted. In the board attachment portion 76, the support component 82 (see FIG. 3) of the circuit unit 80 is attached.

  The device attachment portions 77 are located at both ends in the longitudinal direction of the base portion 72 of the housing body 71 in the plan view of the sensor housing 70. The device attachment portion 77 has a through hole into which the first bolt is inserted.

A detailed configuration of the magnetic flux collecting unit 50 will be described with reference to FIG.
The magnetic flux collecting unit 50 has a configuration in which a first magnetic flux collecting ring 51, a second magnetic flux collecting ring 54, and a magnetic flux collecting holder 60 are integrally formed. The magnetic flux collecting unit 50 has a configuration in which the first magnetic flux collecting ring 51 is located in the upward direction ZA1 of the magnetic flux collecting holder 60. The magnetic flux collecting unit 50 has a configuration in which the second magnetic flux collecting ring 54 is positioned in the downward direction ZA2 of the magnetic flux collecting holder 60. The magnetic flux collecting unit 50 has a configuration in which the magnetic flux collecting rings 51 and 54 are flush with the inner peripheral surface 60 </ b> X of the magnetic flux collecting holder 60.

  The first magnetism collecting ring 51 is formed by bending a long metal plate. The first magnetism collecting ring 51 faces the outer peripheral portion of the first magnetic yoke 101 (see FIG. 3) via a gap in the radial direction ZB. The first magnetism collecting ring 51 has a ring main body 52 and two magnetism collecting projections 53.

The ring body 52 has an annular shape with a gap.
The magnetic flux collecting protrusions 53 are adjacent to each other in the circumferential direction ZC. The magnetic flux collecting protrusion 53 has a shape bent from the lower end portion of the ring main body 52 toward the outward direction ZB2. The magnetic flux collection protrusion 53 faces the upper surface of the magnetic sensor 41 (see FIG. 3) in the axial direction ZA.

  The second magnetism collecting ring 54 is formed by bending a long plate made of the same material as the first magnetism collecting ring 51. The second magnetism collecting ring 54 faces the outer peripheral portion of the second magnetic yoke 102 (see FIG. 3) via a gap in the radial direction ZB. The second magnetism collecting ring 54 has a ring main body 55 and two magnetism collecting projections 56.

The ring body 55 has an annular shape with a gap. The ring body 55 has the same shape as the ring body 52.
The magnetic flux collecting projections 56 are adjacent in the circumferential direction ZC. The magnetic flux collecting projection 56 has a shape bent from the upper end portion of the ring main body 55 toward the outward direction ZB2. The magnetic flux collecting projection 56 faces the lower surface of the magnetic sensor 41 in the axial direction ZA.

  The magnetism collecting holder 60 is formed of the same resin material as the resin material that becomes the base material of the sensor housing 70. The magnetic flux collecting holder 60 uses a nonmagnetic resin as a resin material. The magnetic flux collecting holder 60 has an internal space for accommodating the magnet unit 90 and the magnetic yoke unit 100 (both see FIG. 3). The magnetic flux collecting holder 60 has a holder main body 61 and a holding portion 62. The magnetic flux collecting holder 60 has a configuration in which a holder main body 61 and a holding portion 62 are integrally formed of the same material. The magnetism collecting holder 60 is resin-molded integrally with the magnetism collecting rings 51 and 54.

  The holder main body 61 has an annular shape that is open on both sides in the axial direction ZA. The holder main body 61 holds the magnetism collecting rings 51 and 54 in a state of being in close contact with the ring bodies 52 and 55 of the magnetism collecting rings 51 and 54.

  The holding portion 62 extends from the holder body 61 in the outward direction ZB2. The holding portion 62 has a cylindrical shape. The holding part 62 includes a protrusion holding part 63, a substrate support part 64, and an internal space 65. The holding portion 62 accommodates the magnetic flux collecting protrusions 53 and 56 of the magnetic flux collecting rings 51 and 54 and the magnetic sensor 41 in the internal space 65. The holding part 62 holds the magnetic flux collecting protrusions 53 and 56 in a state of being in close contact with the magnetic flux collecting protrusions 53 and 56 of the magnetic flux collecting rings 51 and 54 in the protrusion holding part 63. The holding portion 62 supports the support component 82 (see FIG. 3) of the circuit unit 80 at the substrate support portion 64.

With reference to FIG. 3, the operation of the torque detection device 30 will be described.
In the torque detection device 30, the sensor housing 70 is formed of a magnetic resin. For this reason, the sensor housing 70 has a function of suppressing the external magnetic field of the torque detection device 30 from affecting the magnetic circuit MC. For this reason, the torque detection device 30 can omit the magnetic shield 213 like the torque detection device 200 shown in FIG. Therefore, the shield end portion 213A of the magnetic shield 213 presses the inner surface 221 of the sensor housing 220 due to the fact that the linear expansion coefficient of the sensor housing 220 is larger than the linear expansion coefficient of the magnetic shield 213 as in the torque detection device 200. Is avoided.

  Since the sensor housing 70 is formed of magnetic resin, the difference between the linear expansion coefficient of the magnetic flux collecting holder 60 and the linear expansion coefficient of the sensor housing 70 is the difference between the linear expansion coefficient of the sensor housing 220 of the torque detector 200 and the magnetic shield 213. It is smaller than the difference from the linear expansion coefficient. In particular, in the sensor housing 70 of the present embodiment, the resin material that is the base material of the magnetic resin is the same as the resin material of the magnetic flux collecting holder 60. For this reason, the difference between the linear expansion coefficient of the magnetic flux collecting holder 60 and the linear expansion coefficient of the sensor housing 70 becomes smaller. Therefore, the occurrence of a large thermal stress in the sensor housing 70 due to the difference between the linear expansion coefficient of the sensor housing 70 and the linear expansion coefficient of the magnetism collecting holder 60 is suppressed.

With reference to FIG. 5, the detection of the magnetic flux density of the torque detector 30 will be described.
FIG. 5A shows a state where torque is not applied between the first shaft 13A and the second shaft 13B (both see FIG. 1) (hereinafter, “neutral state”). FIG. 5B shows a state in which a clockwise torque is applied between the first shaft 13A and the second shaft 13B (hereinafter, “right-rotation state”). FIG. 5C shows a state in which a counterclockwise torque is applied between the first shaft 13A and the second shaft 13B (hereinafter referred to as “counterclockwise rotation state”).

  As the relationship between the magnetic yokes 101 and 102 and the permanent magnet 91, “first N pole facing area”, “first S pole facing area”, “second N pole facing area”, and “second S pole facing area” are defined. . The first N-pole facing area indicates the facing area between the first magnetic yoke 101 and the N pole of the permanent magnet 91. The first S pole facing area indicates the facing area between the first magnetic yoke 101 and the S pole of the permanent magnet 91. The second N pole facing area indicates the facing area between the second magnetic yoke 102 and the N pole of the permanent magnet 91. The second S pole facing area indicates the facing area between the second magnetic yoke 102 and the S pole of the permanent magnet 91.

  As shown in FIG. 5A, in the neutral state, the tip portions of the tooth portions 101A and 102A of the magnetic yokes 101 and 102 are located at the boundary portion between the N pole and the S pole of the permanent magnet 91. At this time, the first N pole facing area and the first S pole facing area are equal to each other. Further, the second N-pole facing area is equal to the second S-pole facing area. Thereby, no magnetic flux is generated between the magnetic flux collecting protrusions 53 of the first magnetic flux collecting ring 51 and the magnetic flux collecting protrusions 56 of the second magnetic flux collecting ring 54. For this reason, the output voltage of the magnetic sensor 41 indicates “0”.

  As shown in FIG. 5B, in the right rotation state, the torsion bar 13D (see FIG. 1) is twisted from the neutral state, so that the relative positions of the magnetic yokes 101 and 102 and the permanent magnet 91 are increased. Changes. Thereby, the first N pole facing area is larger than the first S pole facing area. Further, the second N-pole facing area is smaller than the second S-pole facing area. For this reason, the amount of magnetic flux entering the first magnetic yoke 101 from the N pole of the permanent magnet 91 is larger than the amount of magnetic flux emerging from the first magnetic yoke 101 toward the S pole of the permanent magnet 91. Further, the amount of magnetic flux entering the second magnetic yoke 102 from the N pole of the permanent magnet 91 is smaller than the amount of magnetic flux emerging from the second magnetic yoke 102 toward the S pole of the permanent magnet 91. For this reason, a magnetic flux flows from the magnetic flux collecting protrusion 53 of the first magnetic flux collecting ring 51 to the magnetic flux collecting protrusion 56 of the second magnetic flux collecting ring 54. The magnetic sensor 41 outputs a voltage corresponding to this magnetic flux.

  As shown in FIG. 5C, in the left rotation state, the torsion bar 13D is twisted in the opposite direction to the right rotation state, so that the relative positions of the magnetic yokes 101 and 102 and the permanent magnet 91 are increased. Changes in the opposite direction to when it is rotating clockwise. As a result, the first N-pole facing area is smaller than the first S-pole facing area. Further, the second N pole facing area is larger than the second S pole facing area. For this reason, the amount of magnetic flux entering the first magnetic yoke 101 from the N pole of the permanent magnet 91 is smaller than the amount of magnetic flux emerging from the first magnetic yoke 101 toward the S pole of the permanent magnet 91. Further, the amount of magnetic flux entering the second magnetic yoke 102 from the N pole of the permanent magnet 91 is larger than the amount of magnetic flux entering the S pole of the permanent magnet 91 from the second magnetic yoke 102. For this reason, a magnetic flux flows from the magnetic flux collecting protrusion 56 of the second magnetic flux collecting ring 54 to the magnetic flux collecting protrusion 53 of the first magnetic flux collecting ring 51. The magnetic sensor 41 outputs a voltage corresponding to this magnetic flux.

The steering device 1 of the present embodiment has the following effects.
(1) The torque detection device 30 has a sensor housing 70 formed of magnetic resin. According to this configuration, the sensor housing 70 suppresses the external magnetic field of the torque detection device 30 from affecting the magnetic circuit MC. Therefore, the magnetic shield 213 of the torque detection device 200 as shown in FIG. 8 is omitted. be able to. Therefore, it is possible to suppress a large thermal stress from being generated in the sensor housing 70.

  (2) The torque detection device 30 houses the magnetic flux collecting protrusions 53 and 56 of the magnetic flux collecting rings 51 and 54 in the holding portion 62 of the magnetic flux collecting holder 60. According to this configuration, contact between the sensor housing 70 and each of the magnetic flux collecting protrusions 53 and 56 is suppressed. For this reason, the magnetic flux between each of the magnetic flux collecting protrusions 53 and 56 and the magnetic sensor 41 is suppressed from flowing to the sensor housing 70. Therefore, a decrease in detection accuracy of the magnetic flux density of the magnetic sensor 41 is suppressed.

  (3) The torque detection device 30 has a configuration in which the magnetism collecting holder 60 and the magnetism collecting rings 51 and 54 are integrally molded with resin. According to this configuration, the magnetic flux collecting projections 53 and 56 are in close contact with the projection holding portion 63 of the holding portion 62. For this reason, when the sensor housing 70 is molded, the position of each of the magnetic flux collecting protrusions 53 and 56 with respect to the holding portion 62 is suppressed from changing. Therefore, a decrease in the positional accuracy of the relative positions of the magnetic flux collecting protrusions 53 and 56 and the magnetic sensor 41 is suppressed.

  (4) In the torque detection device 30, the holding portion 62 of the magnetism collecting holder 60 has the substrate support portion 64 that supports the support component 82 of the circuit unit 80. According to this configuration, the relative positions of the magnetic flux collecting protrusions 53 and 56 and the circuit board 81 are determined by the holding portion 62. For this reason, the positional accuracy of the relative positions of the magnetic flux collecting protrusions 53 and 56 and the circuit board 81 is improved as compared with the configuration in which the substrate support portion 64 is assumed to be formed separately from the holding portion 62. Therefore, the positional accuracy of the relative positions of the magnetic flux collecting protrusions 53 and 56 and the magnetic sensor 41 attached to the circuit board 81 is improved.

  (5) The sensor housing 70 has a configuration in which the base portion 72 of the housing main body 71 is positioned in the downward direction ZA2 relative to the magnetic flux collecting unit 50, and the magnetic flux collecting cover portion 74 is positioned in the upward direction ZA1 relative to the magnetic flux collecting unit 50. . According to this configuration, the external magnetic field of the torque detection device 30 is suppressed from affecting the magnetic circuit MC from the upward direction ZA1 and the downward direction ZA2 of the magnetic flux collecting unit 50.

  The steering apparatus includes an embodiment different from the above embodiment. Hereinafter, modifications of the above-described embodiment as other embodiments of the steering apparatus will be described. The following modifications can be combined with each other.

  The sensor unit 40 of the embodiment has a configuration in which the holding portion 62 of the magnetism collecting holder 60 is inserted into the side opening portion 75 of the sensor housing 70. However, the configuration of the sensor unit 40 is not limited to the content exemplified in the above embodiment. For example, the sensor unit 40 of the modified example has a configuration shown in FIG. That is, the sensor housing 70 has a holding cover portion 79. The holding cover portion 79 extends from the side opening portion 75 in the outward direction ZB2. The holding cover portion 79 is in close contact with the entire outer peripheral surface of the holding portion 62.

  According to this configuration, the external magnetic field of the torque detection device 30 affects the portion between the magnetic flux collecting projections 53 and 56 (see FIG. 6B) and the magnetic sensor 41 (see FIG. 3) in the magnetic circuit MC. The effect is suppressed.

  The sensor unit 40 of the embodiment has a configuration in which the sensor housing 70 formed of a magnetic resin is in close contact with the outer peripheral surface 60Y of the magnetism collecting holder 60. However, the configuration of the sensor unit 40 is not limited to the content exemplified in the above embodiment. For example, the sensor unit 40 of the modification has a configuration shown in FIG. That is, the sensor unit 40 according to the modification includes the cover part 110. The cover component 110 is molded integrally with the magnetism collecting unit 50 by pouring molding resin into the outer peripheral side of the magnetism collecting unit 50. The cover component 110 uses a magnetic resin as a molding resin. The magnetic resin is formed by adding ferrite powder to the resin material using the same resin material as the magnetic flux collecting holder 60 as a base material. The cover component 110 has a function of reducing the influence of the external magnetic field of the torque detection device 30 on the magnetic circuit MC.

  As shown in FIG. 7A, the cover component 110 is in close contact with the entire circumference of the outer circumferential surface 60Y of the holder body 61 of the magnetism collecting holder 60 on the inner circumferential surface 110X. As shown in FIG. 7B, the dimension of the cover part 110 in the axial direction ZA is equal to the dimension of the magnetic flux collecting holder 60 in the axial direction ZA.

  The sensor housing 70 is formed of a nonmagnetic resin. The sensor housing 70 is made of the same resin material as that used as the base material of the cover component 110. The sensor housing 70 is in close contact with the outer peripheral surface 110 </ b> Y of the cover component 110 on the inner surface 71 </ b> X of the magnetism collecting portion 73.

  The manufacturing method of the sensor unit 40 includes a magnetic flux collecting unit forming step, a cover part forming step, and a housing forming step. In the magnetic flux collecting unit forming step, the magnetic flux collecting unit 50 is manufactured by integrally molding the magnetic flux collecting holder 60 and the magnetic flux collecting rings 51 and 54 with resin. In the cover component forming step, the cover component 110 is formed integrally with the magnetic flux collecting unit 50 by pouring magnetic resin into the outer peripheral side of the magnetic flux collecting unit 50. In the housing molding step, the resin housing is poured into the outer peripheral side of the unit in which the magnetism collecting unit 50 and the cover part 110 are integrally molded, whereby the sensor housing 70 is molded integrally with the unit. Thus, according to the structure of the sensor unit 40 of a modification, there can exist an effect similar to the effect of (1) of the said embodiment.

  In the sensor unit 40 of the modified example shown in FIG. 7, the cover component 110 has a portion (a portion corresponding to the holding cover portion 79 shown in FIG. 6) that closely contacts the outer peripheral surface of the holding portion 62 of the magnetism collecting holder 60. It can also be changed to a configuration.

-In the sensor unit 40 of the modification shown by FIG. 7, the cover component 110 can also be changed into the shape which covers the upper end surface and lower end surface of the holder main body 61 of the magnetism collection holder 60. FIG.
-In the sensor unit 40 of the modification shown by FIG. 7, the sensor housing 70 can also be shape | molded with magnetic resin.

  In the sensor unit 40 of the modified example shown in FIG. 7, at least one of the materials of the magnetic flux collecting holder 60, the sensor housing 70, and the base material of the cover part 110 may be formed of a material different from other materials.

In the sensor unit 40 of the embodiment, the resin material of the magnetism collecting holder 60 and the resin material that is the base material of the magnetic resin of the sensor housing 70 can be formed of different materials.
In the sensor housing 70 of the embodiment, the sensor housing 70 may be changed to a configuration in which the inner side ZB1 side portion of the sensor housing 70 is formed of magnetic resin and the outer side ZB2 side portion of the sensor housing 70 is formed of nonmagnetic resin. it can.

In the sensor housing 70 according to the embodiment, at least one of the base portion 72 and the magnetism collecting cover portion 74 of the housing main body 71 can be formed of a nonmagnetic resin.
The sensor housing 70 of the embodiment has a configuration in which ferrite powder is added to a resin material as a magnetic resin. However, the configuration of the sensor housing 70 is not limited to the content exemplified in the embodiment. For example, the sensor housing 70 according to the modification has a configuration in which a neodymium powder or a samarium cobalt powder is added to the resin material instead of the ferrite powder. In short, the type of magnetic powder added to the resin material is not limited to ferrite powder.

  In the sensor housing 70 of the embodiment, the ratio of the weight of the ferrite powder to the total weight of the magnetic resin is set to a value such that the sensor housing 70 is not magnetically saturated by the external magnetic field of the torque detection device 30. However, the ratio of the weight of the ferrite powder to the weight of the entire magnetic resin is not limited to the content exemplified in the above embodiment. For example, in the sensor housing 70 according to the modified example, the ratio of the weight of the ferrite powder to the weight of the entire magnetic resin is such that noise due to the external magnetic field of the torque detection device 30 included in the signal of the magnetic sensor 41 is equal to or less than a preset threshold value. Set to the correct value.

  The torque detection device 30 according to the embodiment has two magnetic sensors 41. On the other hand, the torque detection device 30 of the modified example has one magnetic sensor 41. The first magnetism collecting ring 51 of the modified example has one magnetism collecting protrusion 53. The modified second magnetic flux collecting ring 54 has one magnetic flux collecting projection 56. Further, the torque detection device 30 of another modification has a Hall element or an MR element as the magnetic sensor 41 instead of the Hall IC.

  -Steering device 1 of an embodiment has composition as a dual pinion assist type electric power steering device. On the other hand, the steering device 1 of the modified example has a configuration as a column assist type, pinion assist type, rack parallel type, or rack coaxial type electric power steering device.

  The steering device 1 of the embodiment has a configuration as an electric power steering device having the assist device 20. On the other hand, the steering device 1 according to the modification has a configuration as a mechanical steering device in which the assist device 20 is omitted.

  In short, if the steering device has a rack shaft and a pinion shaft, the present steering device can be applied to an electric power steering device other than the dual pinion assist type and a steering device other than the electric power steering device.

Next, technical ideas that can be grasped from the above embodiments will be described together with effects.
(A) The torque detection device according to any one of claims 1 to 3, wherein a dimension of the sensor housing in the axial direction is equal to or greater than a dimension of the magnetic flux collecting holder in the axial direction.

  According to this configuration, the external magnetic field of the torque detection device is prevented from affecting the magnetic circuit as compared with the configuration in which the axial dimension of the sensor housing is assumed to be smaller than the axial dimension of the magnetism collecting holder. The range to do becomes wide. Therefore, it is possible to further suppress the external magnetic field of the torque detection device from affecting the magnetic circuit.

(B) The torque detecting device according to claim 3, wherein the magnetism collecting ring and the magnetism collecting holder are integrally formed.
According to this configuration, when the magnetism collecting ring and the magnetism collecting holder are integrally formed, the magnetism collecting projections of the magnetism collecting ring are in close contact with the holding portion. For this reason, it is suppressed that the position of the magnetic flux collection protrusion with respect to a holding part changes at the time of shaping | molding of a sensor housing. Accordingly, a decrease in the positional accuracy of the relative positions of the magnetic flux collecting protrusions and the magnetic sensor is suppressed.

  (C) a circuit board that is electrically connected to a control device outside the magnetic sensor and the torque detection device; and a support component that supports the circuit board, and the magnetic sensor is attached to the circuit board. The torque detection device according to the additional item (b), wherein the holding portion includes a substrate support portion that supports the support component.

  According to this configuration, the magnetic flux collecting holder determines the relative positions of the magnetic flux collecting projections and the support component. For this reason, the positional accuracy of the relative positions of the magnetic flux collecting projections and the supporting components is improved as compared with the configuration in which the substrate supporting portion is assumed to be formed separately from the holding portion. Therefore, the positional accuracy of the relative position of the magnetic sensor attached to the magnetic flux collecting protrusion and the circuit board is improved.

  ZA ... axial direction, ZA1 ... upward direction, ZA2 ... downward direction, ZB ... radial direction, ZB1 ... inward direction, ZB2 ... outer direction, ZC ... circumferential direction, MC ... magnetic circuit, 1 ... steering device, 2 ... steering wheel, DESCRIPTION OF SYMBOLS 3 ... Steering wheel, 10 ... Steering device main body, 11 ... Column shaft, 12 ... Intermediate shaft, 13 ... Pinion shaft, 13A ... 1st shaft, 13B ... 2nd shaft, 13C ... Pinion gear, 13D ... Torsion bar, 14 ... Rack shaft, 14A ... first gear portion, 14B ... second gear portion, 15 ... rack and pinion mechanism, 16 ... tie rod, 17 ... rack housing, 17A ... fixed part, 20 ... assist device, 21 ... assist motor, 22 ... Worm shaft, 23 ... worm wheel, 24 ... pinion shaft, 24A ... pini 30 ... torque detection device, 31 ... oil seal, 32 ... O-ring, 40 ... sensor unit, 41 ... magnetic sensor, 50 ... magnetic collecting unit, 51 ... first magnetic collecting ring, 52 ... ring body, 53 ... collecting Magnetic projection 54... Second magnetism collecting ring 55. Ring main body 56. Magnetic collecting projection 60. Magnetic collecting holder 60 X Inner circumferential surface 60 Y Outer circumferential surface 61 Holder body 62 Holding portion 63 ... Protrusion holding portion, 64 ... Substrate support portion, 65 ... Internal space, 70 ... Sensor housing, 71 ... Housing main body, 71X ... Inner surface, 72 ... Base portion, 73 ... Magnetic collecting housing portion, 74 ... Magnetic collecting cover portion, 74A ... Inclined part, 74B ... Cylindrical part, 75 ... Side opening part, 76 ... Board mounting part, 77 ... Device mounting part, 78 ... Internal space, 79 ... Holding cover part, 80 ... Circuit board, 81 ... Circuit board, 8 DESCRIPTION OF SYMBOLS ... Supporting part, 90 ... Magnet unit, 91 ... Permanent magnet, 92 ... Core, 100 ... Magnetic yoke unit, 101 ... 1st magnetic yoke, 101A ... Tooth part, 101B ... Connection part, 102 ... 2nd magnetic yoke, 102A ... Tooth part, 102B ... Connection part, 103 ... Yoke holder, 104 ... Intermediate part, 110 ... Cover part, 110X ... Inner peripheral surface, 110Y ... Outer peripheral surface, 200 ... Torque detection device, 210 ... Magnetic collecting unit, 211 ... Magnetic collecting holder 211X ... inner peripheral surface, 211Y ... outer peripheral surface, 212 ... magnetic flux collecting ring, 213 ... magnetic shield, 213A ... shield end, 213B ... corner portion, 213X ... inner peripheral surface, 213Y ... outer peripheral surface, 220 ... sensor housing, 221 ... Inner surface.

Claims (4)

With permanent magnets,
A magnetic yoke disposed in a magnetic field formed by the permanent magnet and changing a relative position with the permanent magnet;
A magnetic flux collecting unit formed in a ring shape by a non-magnetic resin and surrounding the magnetic yoke; and an annular magnetic flux collecting unit that is held on the inner peripheral side of the magnetic flux collecting holder and has a magnetic flux collecting ring that collects the magnetic flux of the magnetic yoke;
A magnetic sensor for detecting a magnetic flux of a magnetic circuit formed by the permanent magnet, the magnetic yoke, and the magnetism collecting ring;
A sensor housing formed integrally with the magnetic flux collecting unit in a state of being in close contact with the outer circumferential surface of the magnetic flux collecting holder by pouring a magnetic resin in which magnetic powder is added to a resin material into the outer circumferential side of the magnetic flux collecting holder. A torque detection device provided. With permanent magnets,
A magnetic yoke disposed in a magnetic field formed by the permanent magnet and changing a relative position with the permanent magnet;
A magnetic flux collecting unit formed in a ring shape by a non-magnetic resin and surrounding the magnetic yoke; and an annular magnetic flux collecting unit that is held on the inner peripheral side of the magnetic flux collecting holder and has a magnetic flux collecting ring that collects the magnetic flux of the magnetic yoke;
A magnetic sensor for detecting a magnetic flux of a magnetic circuit formed by the permanent magnet, the magnetic yoke, and the magnetism collecting ring;
A cover part molded integrally with the magnetic flux collecting unit in a state of being in close contact with the outer circumferential surface of the magnetic flux collecting holder by pouring a magnetic resin in which magnetic powder is added to a resin material into the outer circumferential side of the magnetic flux collecting holder;
A torque detector comprising: a sensor housing formed integrally with the cover part by a resin poured into the outer peripheral side of the cover part. The magnetic flux collecting holder has an annular holder main body that surrounds the magnetic yoke, and a holding portion that protrudes outward from the holder main body,
The magnetic flux collecting ring has a magnetic flux collecting projection that protrudes outward from the holder body and faces the magnetic sensor;
The torque detection device according to claim 1, wherein the magnetic flux collecting protrusion is accommodated in the holding portion.   A steering device comprising the torque detection device according to claim 1.