JP4905792B2 - Torque detection device - Google Patents

Description

  The present invention relates to a torque detection device.

The torque detection device includes, for example, an input shaft and an output shaft that are coaxially connected by a torsion bar, a permanent magnet fixed to the input shaft, and a soft magnetic material that is arranged in a magnetic field of the permanent magnet to form a magnetic circuit. And a plurality of magnetic yokes fixed to the output shaft, a pair of magnetic flux collecting rings for inducing magnetic flux from the magnetic yokes, and a magnetic sensor for detecting the magnetic flux induced in the magnetic flux collecting ring. Each of the pair of magnetism collecting rings has claw pieces arranged to face each other. A magnetic sensor is disposed between the pair of claw pieces (see, for example, Patent Document 1).
JP 2004-101277 A

By the way, a torque detection apparatus may have a unit in which a magnetic sensor is molded with a synthetic resin. This unit is usually fixed to the sensor housing with a screw and requires a metal cylinder member for receiving a fixing screw, and the number of parts is large.
In addition, external magnetism may adversely affect the magnetic sensor. In order to prevent this, it is considered that a magnetic shield plate is provided in the above-described unit. In this case, however, the number of parts is further increased.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a torque detector that can suppress the adverse effects of magnetism from the outside and has a small number of parts.

  The torque detection device (16) of the present invention is formed by molding a pair of magnetism collecting rings (34A, 34B) magnetically coupled to the corresponding soft magnetic bodies (29A, 29B) with a synthetic resin (40). A first unit (38) attached to the attachment target member (30), and a second unit (39) formed by molding the magnetic sensor (35A, 35B) with a synthetic resin (41). The unit includes an insertion recess (43) and a magnetic shield plate mounting portion (38e) surrounding the insertion recess, and the second unit is attached to the magnetic shield plate mounting portion along the magnetic shield plate mounting portion. The metal magnetic shield plate (37B) having a shape along the portion and the central portion (37b) of the magnetic shield plate is inserted into the insertion recess in a state of holding the magnetic sensor. A fixing screw (32) including an insertion convex portion (44) and passing through a pair of screw insertion holes (37a) formed in the magnetic shield plate is formed in the magnetic shield plate mounting portion of the first unit. By inserting the screw insertion hole (38i) and screwing into the screw hole (30g) provided in the attachment target member, the second unit and the first unit are fixed to the attachment target member in a co-tightened state. It is characterized by being. According to the present invention, since the metal magnetic shield plate can receive the fixing screw at the peripheral portion of the screw insertion hole, it is not necessary to separately provide a metal member for receiving the fixing screw in the second unit. As a result, the manufacturing cost can be reduced. Moreover, since the magnetic shield plate and the first unit are fixed together, the manufacturing cost can be further reduced.

In the present invention, the magnetic shield plate may be attached to the second unit during molding of the synthetic resin of the second unit. In this case, it is not necessary to separately provide a member for fixing the magnetic shield plate to the second unit, so that the manufacturing cost can be reduced.
In addition, although the alphanumeric characters in the parentheses indicate reference signs of corresponding components in the embodiments described later, the scope of the claims is not limited by these reference signs.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this embodiment, the torque detection device will be described as applied to an electric power steering device of an automobile. However, the torque detection device can also be applied to devices and devices other than the electric power steering device.
FIG. 1 is a schematic diagram showing a schematic configuration of an electric power steering apparatus to which a torque detection device according to an embodiment of the present invention is applied. Referring to FIG. 1, an electric power steering apparatus 1 includes a steering shaft 4 that transmits a steering torque applied to a steering wheel 3 as a steering member in order to steer a steered wheel 2, and a steering torque from the steering shaft 4. An intermediate shaft unit as a shaft coupling provided between the steering shaft 4 and the steering mechanism 5 for transmitting the rotation between the steering mechanism 5 composed of, for example, a rack and pinion mechanism for steering the steering wheel 2 6.

  The steering shaft 4 is rotatably supported by a steering column 7. The steering column 7 is supported on the vehicle body 9 via a bracket 8. A steering wheel 3 is connected to one end of the steering shaft 4. An intermediate shaft unit 6 is connected to the other end of the steering shaft 4. The intermediate shaft unit 6 includes a power transmission shaft 10 as an intermediate shaft and universal joints 11 and 12.

  The steering mechanism 5 includes a pinion shaft 13, a rack bar 14 as a steered shaft extending in the left-right direction of the automobile (a direction orthogonal to the straight traveling direction), and a rack housing 15 that supports the pinion shaft 13 and the rack bar 14. And have. The pinion teeth 13a of the pinion shaft 13 and the rack teeth 14a of the rack bar 14 mesh with each other. Each end of the rack bar 14 is connected to the corresponding steering wheel 2 via a tie rod and a knuckle arm (not shown).

When the steering wheel 3 is steered, steering torque is transmitted to the steering mechanism 5 via the steering shaft 4 and the intermediate shaft unit 6. Thereby, the steering wheel 2 can be steered.
The electric power steering apparatus 1 can obtain a steering assist force according to the steering torque. That is, the electric power steering device 1 includes a torque detection device 16 that detects steering torque, an ECU (Electronic Control Unit) 17 as a control unit, an electric motor 18 for assisting steering, and a gear device. And a speed reducer 19. In the present embodiment, the torque detection device 16, the electric motor 18, and the speed reducer 19 are provided in association with the steering column 7.

The steering column 7 has a column tube 20 and a housing 21. The housing 21 accommodates and supports at least a part of the torque detection device 16, supports the electric motor 18, and constitutes a part of the speed reducer 19.
The steering shaft 4 includes an input shaft 22, an output shaft 23, and a torsion bar 24 as a lower portion in the axial direction, and a connecting shaft 25 as an upper portion in the axial direction. The input shaft 22 and the output shaft 23 are connected to each other on the same axis via a torsion bar 24. The input shaft 22 is connected to the steering wheel 3 via the connecting shaft 25. The output shaft 23 is connected to the intermediate shaft unit 6. When steering torque is input to the input shaft 22, the torsion bar 24 is elastically torsionally deformed, whereby the input shaft 22 and the output shaft 23 are relatively rotated.

The torque detection device 16 is provided in association with the torsion bar 24 of the steering shaft 4 and detects torque based on the relative rotational displacement amount between the input shaft 22 and the output shaft 23 via the torsion bar 24. The torque detection result is given to the ECU 17.
The ECU 17 controls the electric motor 18 based on the above torque detection result, a vehicle speed detection result given from a vehicle speed sensor (not shown), and the like. The speed reducer 19 includes a worm shaft 26 that is driven by the electric motor 18 and a worm wheel 27 that meshes with the worm shaft 26. The worm wheel 27 and the output shaft 23 are fixed to each other and rotate integrally.

  When the steering wheel 3 is operated, the steering torque is detected by the torque detection device 16, and the electric motor 18 generates a steering assist force according to the torque detection result and the vehicle speed detection result. The steering assist force is transmitted to the steering mechanism 5 via the speed reducer 19. At the same time, the movement of the steering wheel 3 is also transmitted to the steering mechanism 5. As a result, the wheel 2 is steered and the steering is assisted.

  FIG. 2 is an exploded perspective view of the torque detector 16 of FIG. FIG. 3 is an exploded perspective view of a main part of the torque detector 16 of FIG. 4A to 4C are schematic diagrams for explaining the operation of the torque detection device 16 of FIG. 2, and FIG. 4D shows the twist angle and magnetic flux density generated between the input shaft 22 and the output shaft 23. It is a graph which shows a relationship. FIG. 5 is a cross-sectional view of the torque detection device 16 of FIG. 6 is a cross-sectional view taken along a line S6-S6 in FIG.

With reference to FIGS. 2, 5, and 6, the torque detection device 16 of the present embodiment includes the input shaft 22, the output shaft 23, and the torsion bar 24, and each of these members 22, 23, As a magnetic circuit forming member that forms a magnetic circuit in which the magnetic flux changes according to the torque acting on 24, a permanent magnet 28 and a pair of magnetic yokes 29A and 29B as soft magnetic bodies are provided.
The torque detection device 16 is a fixing member and a sensor housing 30 as an attachment target member, a fixed side unit 31 attached to the sensor housing 30, and fixing for fixing the fixed side unit 31 to the sensor housing 30. Two fixing screws 32 as members, an annular sealing member 33A for sealing between the sensor housing 30 and the fixed side unit 31, and an annular sealing member 33B for sealing inside the fixed side unit 31 And have.

The input shaft 22, the output shaft 23, the torsion bar 24, the permanent magnet 28, and the pair of magnetic yokes 29 </ b> A and 29 </ b> B constitute a movable part of the torque detection device 16. The sensor housing 30 and the fixed side unit 31 constitute a fixed portion of the torque detection device 16.
The sensor housing 30 has a cylindrical shape as a part of the housing 21 described above, and has a cavity 30a therein. The side part 30d of the sensor housing 30 has a communication hole 30b that forms an outer periphery and communicates the inside and the outside. An attachment opening 30e for a communication hole and an attachment surface 30c for attaching the fixed side unit 31 are formed in the side portion 30d.

  The attachment surface 30c is formed as an annular flat surface surrounding the attachment opening 30e. The inner and outer contours of the flat surface have a substantially rectangular shape extending long in the direction perpendicular to the axial direction S when viewed from the radial direction R. An annular step 30f that accommodates the sealing member 33A and two screw holes 30g for the fixing screw 32 are formed in the attachment surface 30c along the edge of the attachment opening 30e. Each screw hole 30g is independent of the cavity 30a of the sensor housing 30 and has a predetermined length with a bottom. Note that the attachment surface 30 c may be formed on a separate member (not shown) fixed to the sensor housing 30.

  The fixed-side unit 31 includes a pair of magnetism collecting rings 34A and 34B as auxiliary soft magnetic bodies, two magnetic sensors 35A and 35B for detecting magnetic flux induced by the pair of magnetism collecting rings 34A and 34B, a power supply unit, and a signal A circuit board 36 as a processing unit and magnetic shield plates 37A and 37B made of a metal plate for suppressing adverse effects on the inside of the stationary unit 31 due to magnetism from the outside are provided. The fixed unit 31 includes a first unit 38 and a second unit 39 that are connected to each other.

  In the following description, the axial direction S, radial direction R, and circumferential direction T of the steering shaft 4 are also simply referred to as axial direction S, radial direction R, and circumferential direction T, respectively. The axial direction S, the radial direction R, and the circumferential direction T are respectively the axial direction and the diameter corresponding to the input shaft 22, the output shaft 23, the permanent magnet 28, the magnetic yokes 29A and 29B, and the magnetism collecting rings 34A and 34B. Direction and circumferential direction. The direction in which the first unit 38 and the second unit 39 of the fixed side unit 31 are connected to each other in one of the radial directions R is referred to as a connecting direction RP.

The first unit 38 has a pair of magnetism collecting rings 34A and 34B as a part for forming a magnetic circuit in the fixed side unit 31, and a magnetic shield plate 37A, and these portions 34A, 34B and 37A are used as insulators. The synthetic resin 40 is integrally molded.
The first unit 38 has an end portion 38a disposed closer to the second unit 39 with respect to the connection direction RP, and an annular portion 38c as a portion disposed in the sensor housing 30 through the communication hole 30b. . The end 38a has a flange 38b. The flange 38b extends from the annular portion 38c in the axial direction S and the circumferential direction T, and is larger than the corresponding dimension of the mounting opening 30e of the communication hole 30b of the sensor housing 30 in both directions S and T. The resin 40 is used.

  The second unit 39 includes magnetic sensors 35A and 35B and a circuit board 36 as a part for forming an electric circuit, and a magnetic shield plate 37B. These portions 35A, 35B, 36, and 37B are integrally molded with a synthetic resin 41 as an insulator, and are attached to the second unit 39 when the synthetic resin 41 is molded. The second unit 39 includes a main body 39c and a flange 39b. The second unit 39 includes an end 39a that is disposed closer to the first unit 38 with respect to the connection direction RP.

  The magnetic shield plate 37B is made of a hard metal plate, and a steel plate as a magnetic material can be used. Further, a material having a high magnetic permeability such as permalloy, amorphous, silicon steel plate, or pure iron may be used. The magnetic shield plate 37 </ b> B is formed in the same shape and size as the end portion 38 a of the first unit 38 when viewed from the connection direction RP, and covers the end portion 38 a of the first unit 38. The magnetic shield plate 37B has a shape along the joint portion 38e as a magnetic shield plate mounting portion. This shape is, for example, a plate shape that forms a flat surface that touches the joint 38e while covering the joint 38e. The magnetic shield plate 37B has a screw insertion hole 37a penetrating in the connecting direction RP and a through hole 37c penetrating the central portion 37b of the magnetic shield plate 37B. A synthetic resin 41 is formed through the through hole 37c. The synthetic resin 41 is disposed outside the through hole 37c on both sides in the connecting direction RP and is adjacent to the through hole 37c and has a diameter larger than that of the through hole 37c. Further, the magnetic shield plate 37B is formed with a thickness t such as 2 to 4 mm so as not to be deformed by the axial force when receiving the axial force when the fixing screw 32 is screwed. Yes.

The main portion 39c is formed by integrally molding a magnetic resin 35A, 35B, a circuit board 36, and a central portion 37b as a part of the magnetic shield plate 37B with a synthetic resin 41.
The flange 39b extends in the circumferential direction T from the main body 39c. The entire flange 39b is formed by the magnetic shield plate 37B. Further, the flange 39b has the two screw insertion holes 37a described above. The two screw insertion holes 37a are disposed on both sides of the main body 39c with respect to the circumferential direction T.

  In the sensor housing 30, a permanent magnet 28 and a pair of magnetic yokes 29A and 29B are accommodated. Further, the first unit 38 and the second unit 39 are connected to each other along the radial direction R of the steering shaft 4. The first unit 38 is disposed relatively radially inward of the steering shaft 4 through the mounting opening 30e of the communication hole 30b of the sensor housing 30. The magnetism collecting rings 34 </ b> A and 34 </ b> B of the annular portion 38 c as a part of the first unit 38 protrude into the sensor housing 30. The second unit 39 is disposed relatively outward in the radial direction of the steering shaft 4 and outside the sensor housing 30.

  In the present embodiment, the flange 38b of the end 38a of the first unit 38 is attached to the attachment surface 30c of the sensor housing 30, and the flange 39b of the second unit 39 is connected to the flange 38b of the first unit 38. Accordingly, the two fixing screws 32 are screwed to and attached to the attachment surface 30 c of the sensor housing 30. The fixing screw 32 fastens the flange 38b of the first unit 38 and the flange 39b of the second unit 39 together.

2 and 5, the permanent magnet 28 has a cylindrical shape and is fixed to the input shaft 22 so as to rotate concentrically and integrally therewith. On the outer periphery of the permanent magnet 28, a plurality of magnetic poles, for example, 24 poles (12 poles of N and S poles) are magnetized at equal intervals in the circumferential direction T.
Each of the magnetic yokes 29A and 29B has a cylindrical shape, surrounds the permanent magnet 28 in a non-contact manner from the outside in the radial direction, and is disposed in a magnetic field formed by the permanent magnet 28, thereby magnetically attaching to the permanent magnet 28. Are combined. The pair of magnetic yokes 29 </ b> A and 29 </ b> B are fixed so as to be non-contact with each other and immovable relative to each other, and are concentrically and integrally rotated with the output shaft 23. When the relative position between the magnetic yokes 29A and 29B and the permanent magnet 28 in the circumferential direction T changes, a pair of magnetic fluxes generated in the magnetic circuit formed by the magnetic yokes 29A and 29B and the permanent magnet 28 changes. The magnetic yokes 29A and 29B are configured.

  Referring to FIG. 2, FIG. 3, and FIG. 5, each magnetic yoke 29A, 29B has a disk-shaped ring 29a and a plurality of, for example, twelve, for example, 12 rising from the inner periphery of the plate surface of this ring 29a. Claw 29b. The rings 29a of the two magnetic yokes 29A and 29B are opposed to each other at a predetermined interval in the axial direction S and are arranged concentrically with each other. The claws 29b of the two magnetic yokes 29A and 29B protrude toward each other and are alternately and evenly arranged so as to be shifted from each other in the circumferential direction T. In this state, the two magnetic yokes 29 </ b> A and 29 </ b> B are integrally molded with the synthetic resin 42. The molded product thus molded has a cylindrical shape.

  Referring to FIG. 3, FIG. 5, and FIG. 6, the two magnetism collecting rings 34A and 34B are magnetically coupled to the corresponding magnetic yokes 29A and 29B, respectively, and the magnetic fluxes from the corresponding magnetic yokes 29A and 29B are respectively received. The magnetic sensors 35A and 35B are guided. The two magnetism collecting rings 34A and 34B have an annular shape and surround the outer periphery of the corresponding magnetic yokes 29A and 29B concentrically and in a non-contact manner from the outside in the radial direction.

  Each of the magnetism collecting rings 34A and 34B has an annular main body 34a and two claw pieces 34b extending radially outward from the main body 34a. The two claw pieces 34b are formed in the same shape as each other and are spaced apart from each other in the circumferential direction T. The two magnetism collecting rings 34A and 34B are fixed in the following state without contact with each other. One claw piece 34b of one magnetism collecting ring 34A and one claw piece 34b of the other magnetism collecting ring 34B are paired with each other, extend in directions close to each other, and face along the axial direction S. is doing. Similarly, the other claw piece 34b of one magnetic flux collecting ring 34A and the other claw piece 34b of the other magnetic flux collecting ring 34B are paired with each other. A predetermined amount of gap is opened as the insertion recess 43 in the axial direction S between the pair of claw pieces 34 b. In this state, the pair of magnetism collecting rings 34 </ b> A and 34 </ b> B are molded and integrated with the synthetic resin 40. The magnetism collecting rings 34A and 34B are magnetically coupled to each other via a claw piece 34b.

  The pair of magnetic sensors 35 </ b> A and 35 </ b> B are arranged in the circumferential direction T. Each magnetic sensor 35 </ b> A, 35 </ b> B includes a Hall IC as a Hall element, is inserted between a corresponding pair of claw pieces 34 b, and is electrically connected to the circuit board 36. Referring to FIGS. 1 and 6, circuit board 36 supplies power to magnetic sensors 35 </ b> A and 35 </ b> B, performs predetermined signal processing on the signals input from magnetic sensors 35 </ b> A and 35 </ b> B, and outputs the processed signals to ECU 17. To do. The circuit board 36 includes, for example, a circuit component and a printed wiring board, and these are assembled.

  4B and 5, in the neutral state where no torque acts between the input shaft 22 and the output shaft 23, the tips of the claws 29 b of the magnetic yokes 29 </ b> A and 29 </ b> B are connected to the N pole and S of the permanent magnet 28. It is designed to point to the pole boundary. At this time, in each claw 29b of the magnetic yokes 29A and 29B, the area facing the north pole of the permanent magnet 28 is equal to the area facing the south pole, so that the magnetic flux entering from the north pole and the magnetic flux going out to the south pole are As a result, no magnetic flux is generated between the pair of magnetic yokes 29A and 29B. Therefore, the magnetic sensors 35A and 35B do not detect magnetic flux.

4A and 5, when a one-way torque acts between the input shaft 22 and the output shaft 23, the torsion bar 24 is twisted, and the claws 29b of the pair of magnetic yokes 29A and 29B and The relative position of the permanent magnet 28 changes.
At this time, in each claw 29b of one magnetic yoke 29A, the area facing the N pole of the permanent magnet 28 becomes larger than the area facing the S pole of the permanent magnet 28, and from the N pole in one magnetic yoke 29A. The incoming magnetic flux is greater than the magnetic flux exiting the S pole. In each claw 29b of the other magnetic yoke 29B, the area facing the N pole of the permanent magnet 28 is smaller than the area facing the S pole of the permanent magnet 28, and the magnetic flux entering from the N pole in the other magnetic yoke 29B is reduced. It becomes smaller than the magnetic flux which goes out to S pole.

Magnetic fluxes generated in the magnetic yokes 29A and 29B are respectively induced by the corresponding magnetism collecting rings 34A and 34B. As a result, a magnetic flux is generated from the claw piece 34b of the magnetic flux collecting ring 34A corresponding to one magnetic yoke 29A to the claw piece 34b of the magnetic flux collecting ring 34B corresponding to the other magnetic yoke 29B. This magnetic flux is detected by the magnetic sensors 35A and 35B.
4C and FIG. 5, on the other hand, when torque in the other direction acts between the input shaft 22 and the output shaft 23, a pair of magnetic yokes is opposite to the case where the torque in one direction acts. The relative positions of the claws 29b of 29A and 29B and the permanent magnet 28 change in opposite directions, and magnetic fluxes are generated in opposite directions in the magnetic yokes 29A and 29B. As a result, a magnetic flux is generated from the claw piece 34b of the magnetic flux collecting ring 34B corresponding to the other magnetic yoke 29B to the claw piece 34b of the magnetic flux collecting ring 34A corresponding to the one magnetic yoke 29A, and this magnetic flux is detected.

  Please refer to FIG. 4D and FIG. In FIG. 4D, points indicating the relationship between the twist angle of the torsion bar 24 and the magnetic flux density corresponding to the states of FIGS. 4A, 4B, and 4C are denoted by reference numerals 4A, 4B, and 4C. Within the range of the torsion angle of the torsion bar 24 actually used, the magnetic flux density generated between the claw pieces 34b forming a pair of the pair of magnetism collecting rings 34A, 34B is in each claw 29b of each magnetic yoke 29A, 29B. This is proportional to the difference between the area facing the N pole and the area facing the S pole, and this difference is proportional to the torsion angle of the torsion bar 24, and thus the torque acting between the input shaft 22 and the output shaft 23. Is proportional to the size of That is, the torque can be known based on the detected magnetic flux density. Moreover, the magnetic sensors 35A and 35B can detect the average of the magnetic flux density generated on the entire circumference of the magnetic yokes 29A and 29B by the magnetic flux collecting rings 34A and 34B.

With reference to FIGS. 2, 5, and 6, in the present embodiment, the fixed unit 31 is divided into a first unit 38 and a second unit 39. The first unit 38 and the second unit 39 are configured as separate parts, are mechanically connected to each other in the connection direction RP described above, and can be separated from each other as necessary.
The end portion 38a of the first unit 38 includes a pair of protrusions protruding from the bottom of the fitting recess 38f, a joint 38e as a magnetic shield plate mounting portion, a hollow fitting recess 38f surrounded by the joint 38e. The recess forming portion 38g, the mounted surface 38h attached to the mounting surface 30c of the sensor housing 30, and the two screw insertion holes 38i through which the two fixing screws 32 are respectively inserted.

The mounted surface 38h is a flat surface having a rectangular ring shape surrounding the annular portion 38c of the first unit 38, and is formed on one surface of the flange 38b and on the back side of the joint portion 38e. The sensor housing 30 is opposed to the mounting surface 30c.
The joining portion 38e is formed in a flat annular shape on the end surface of the flange 38b, and is in contact with the attached surface 39h as one surface of the magnetic shield plate 37B.

The screw insertion holes 38i pass through the attached surface 38h and the joint 38e, and are spaced apart from each other across the fitting recess 38f.
The fitting recess 38f has an inner peripheral surface that is circular when viewed from the connecting direction RP. In addition, a pair of recess forming portions 38g is disposed at the center of the bottom of the fitting recess 38f.
Each recess forming portion 38g includes two claw pieces 34b of the corresponding magnetism collecting rings 34A and 34B and a synthetic resin 40.

The insertion recess 43 is formed between the pair of recess formation portions 38g and between the claw pieces 34b of the magnetism collecting rings 34A and 34B with a predetermined gap amount, and has a diameter along the connection direction RP as the insertion direction. Open to the outside of the direction.
The end portion 39a of the second unit 39 is an end surface of the end portion 39a and is a flat and annular mounting surface 39h formed on one surface of the magnetic shield plate 37B, and a fitting convex portion 39f protruding from the end surface. And a magnetic flux detecting insertion convex portion 44 projecting from the top surface of the fitting convex portion 39f, and two guiding convex portions 39g projecting on the same side as the insertion convex portion 44. The insertion convex portion 44 includes a pair of magnetic sensors 35 </ b> A and 35 </ b> B and a synthetic resin 41.

The fitting convex portion 39f is disposed so as to be surrounded by the attached surface 39h, protrudes from the attached surface 39h at a predetermined height, and has a circular shape when viewed from the connection direction RP. The fitting protrusion 39f has a cylindrical outer peripheral surface and a top surface. An insertion convex portion 44 and two guide convex portions 39g protrude in the connecting direction RP from the top surface.
The two guide convex portions 39g are arranged near the outer periphery of the top surface of the fitting convex portion 39f, are arranged on opposite sides of the insertion convex portion 44 with respect to the axial direction S, and extend along the connecting direction RP. It extends in a straight line. When the guide convex portion 39g contacts the inner peripheral surface of the fitting concave portion 38f, the relative movement of the first unit 38 and the second unit 39 is guided.

  The fixing screw 32 has a head, a shaft portion having a smaller diameter than the head and extending from the head, and a male screw formed at the tip of the shaft portion. The fixing screw 32 is inserted into the screw insertion hole 37a of the second unit 39, and is inserted into the screw insertion hole 38i of the first unit 38. The male screw at the tip of the inserted fixing screw 32 is the sensor housing 30. Are screwed into the female screw 30g.

  A flange 38 b of the end 38 a of the first unit 38 is attached to the attachment surface 30 c of the sensor housing 30. The attachment surface 39h of the second unit 39 is placed along the joint 38e of the first unit 38, and the magnetic shield plate 37B of the second unit 39 is screwed. The first unit 38 is sandwiched between the mounting surface 30 c of the sensor housing 30 and the magnetic shield plate 37 </ b> B of the second unit 39. In this state, the insertion convex portion 44 protrudes from the central portion 37b of the magnetic shield plate 37B in the connecting direction RP, and is inserted into the insertion concave portion 43 while holding the magnetic sensors 35A and 35B. One magnetic sensor 35A is disposed between one pair of claw pieces 34b, and the other magnetic sensor 35B is disposed between the other pair of claw pieces 34b. The fitting convex portion 39 f of the end portion 39 a of the second unit 39 is fitted into the fitting concave portion 38 f of the end portion 38 a of the first unit 38. The fitting concave portion 38f and the fitting convex portion 39f are fitted to each other, whereby relative movement between the first unit 38 and the second unit 39 in the circumferential direction T and the axial direction S is restricted. .

  The torque detector 16 of the present embodiment is formed by molding a pair of magnetic flux collecting rings 34A and 34B magnetically coupled to the corresponding magnetic yokes 29A and 29B, which are soft magnetic bodies, with a synthetic resin 40. A first unit 38 attached to the sensor housing 30 as a member and a second unit 39 formed by molding the magnetic sensors 35A and 35B with a synthetic resin 41 are provided. The first unit 38 includes an insertion recess 43 and a joint 38 e as a magnetic shield plate mounting portion surrounding the insertion recess 43. The second unit 39 protrudes from the central portion 37b of the magnetic shield plate 37B having a shape along the joint portion 38e and the magnetic shield plate 37B and holds the magnetic sensors 35A and 35B in the insertion recess 43. The insertion convex part 44 inserted is included. A fixing screw 32 that passes through a pair of screw insertion holes 37a formed in the magnetic shield plate 37B passes through a screw insertion hole 38i formed in the joint portion 38e of the first unit 38, and is provided in the sensor housing 30. The second unit 39 and the first unit 38 are fixed to the sensor housing 30 in a tightened state by being screwed into the screw holes 30g.

  According to the present embodiment, since the metal magnetic shield plate 37B can receive the fixing screw 32 at the peripheral edge portion of the screw insertion hole 37a, it is conventionally required to receive the fixing screw 32 in the second unit 39. There is no need to provide a separate metal member (not shown). As a result, the manufacturing cost can be reduced. Further, since the magnetic shield plate 37B and the first unit 38 are fixed together, the manufacturing cost can be further reduced.

Further, the magnetic shield plate 37B is attached to the second unit 39 when the synthetic resin 41 of the second unit 19 is molded. In this case, it is not necessary to separately provide a member for fixing the magnetic shield plate 37B to the second unit 39, so that the manufacturing cost can be reduced.
In addition, since the first unit 38 including the magnetism collecting rings 34A and 34B and the second unit 39 including the magnetic sensors 35A and 35B are configured as separate units, for example, the magnetic sensors 35A and 35B are configured. When it is necessary to replace them, it is possible to replace only the second unit 39 including the magnetic sensors 35A and 35B and not to replace the first unit 38. This is because, since the steering shaft 4 is inserted into the first unit 38, it is necessary to disassemble the steering column 7 and pull out the steering shaft 4 in order to replace the first unit 38. This is because the replacement of the first unit 38 takes time. Therefore, the magnetic sensors 35A and 35B can be exchanged economically and in a short time. Similarly, when only the first unit 38 is exchanged, it is economical as well.

Further, the fixed-side unit 31 is divided into a first unit 38 including the magnetism collecting rings 34A and 34B and a second unit 39 including the magnetic sensors 35A and 35B. Therefore, the torque detection device 16 can be easily applied to various devices and apparatuses.
Further, since the magnetic shield plates 37A and 37B are provided, the output signals of the magnetic sensors 35A and 35B can be hardly affected by the external magnetism, and as a result, the response of the output signal by a filter for suppressing this adverse effect. It can suppress that property falls. Therefore, the steering feeling of the electric power steering apparatus 1 can be enhanced.

Moreover, the following modifications can be considered about this embodiment. In the following description, differences from the above-described embodiment will be mainly described, and the same components are denoted by the same reference numerals and description thereof is omitted.
For example, the fixing screw 32 may pass through the sensor housing 30 and be screwed into the nut. When the permanent magnet 28 is fixed to the output shaft 23 and the pair of magnetic yokes 29A and 29B are fixed to the input shaft 22, at least one of the claw pieces 34b of the magnetic flux collecting rings 34A and 34B and the magnetic sensors 35A and 35B. Is provided at one or three or more places, the number of claw pieces 34b of the magnetic flux collecting rings 34A and 34B may not match the number of magnetic sensors 35A and 35B. Although the torque detection device 16 and the electric motor 18 as a drive source are provided in the steering column 7, a case where the torque detection device 16 and the electric motor 18 as a drive source are provided in the steering mechanism 5 is also conceivable. In addition, various design changes can be made within the scope of matters described in the claims.

1 is a schematic configuration diagram of an electric power steering device to which a torque detection device according to an embodiment of the present invention is applied. It is a disassembled perspective view of the torque detection apparatus shown in FIG. It is a disassembled perspective view of the principal part of the torque detection apparatus of FIG. 4A to 4C are schematic diagrams for explaining the operation of the torque detection device of FIG. 2, and FIG. 4D shows the relationship between the twist angle generated between the input shaft and the output shaft and the magnetic flux density. It is a graph. It is sectional drawing of the torque detection apparatus of FIG. 2, and shows the S5-S5 cross section of FIG. FIG. 6 is a cross-sectional view taken along a line S6-S6 in FIG.

Explanation of symbols

16 ... Torque detection device, 29A, 29B ... Magnetic yoke (soft magnetic material), 30 ... Sensor housing (attachment target member), 30g ... Screw hole, 32 ... Fixing screw, 34A, 34B ... Magnetic collecting ring, 35A, 35B ... Magnetic sensor 37B ... Magnetic shield plate, 37a, 38i ... Screw insertion hole, 37b ... Center portion, 38 ... First unit, 38e ... Joint (magnetic shield plate mounting portion), 39 ... Second unit, 40 ... Synthetic resin (of the first unit), 41 ... Synthetic resin (of the second unit), 43 ... Insertion concave part, 44 ... Insertion convex part

Claims (2)

A first unit that is formed by molding a pair of magnetism-collecting rings that are magnetically coupled to the corresponding soft magnetic bodies with a synthetic resin, and is attached to a member to be attached;
A second unit formed by molding a magnetic sensor with a synthetic resin,
The first unit includes an insertion recess and a magnetic shield plate mounting portion surrounding the periphery of the insertion recess,
The second unit is inserted into the insertion recess in a state of projecting from the central portion of the magnetic shield plate and holding the magnetic sensor while having a shape along the magnetic shield plate mounting portion. Including an insertion convex part,
A fixing screw that passes through a pair of screw insertion holes formed in the magnetic shield plate passes through a screw insertion hole formed in the magnetic shield plate attachment portion of the first unit, and the screw provided in the attachment target member The torque detection device, wherein the second unit and the first unit are fixed to the attachment target member together by being screwed into the hole.   2. The torque detection device according to claim 1, wherein the magnetic shield plate is attached to the second unit when the synthetic resin of the second unit is molded.

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