JP5513998B2 - Torque sensor - Google Patents

Description

  The present invention relates to a torque sensor that detects torque acting on a torsion bar through magnetic force.

  Conventionally, as a torque sensor provided in a steering system of a vehicle, a non-contact type sensor that detects a steering torque acting on a rotating shaft through a magnetic force is used.

  As this type of torque sensor, all disclosed in Patent Documents 1 to 4 are a torsion bar that is rotatably accommodated in a housing, a magnetic generator connected to one end of the torsion bar, and a torsion A rotating magnetic circuit unit (multipole yoke) connected to the other end of the bar, a fixed magnetic circuit unit fixed to the housing, and a magnetic sensor for detecting a magnetic flux density guided to the fixed magnetic circuit unit.

  When the torsion bar is torsionally deformed by the torque acting on the torsion bar, the relative position in the rotation direction of the magnetism generating unit and the rotating magnetic circuit unit is changed, and accordingly, the fixed magnetic circuit unit from the magnetism generating unit through the rotating magnetic circuit unit. The magnetic flux density led to changes. The magnetic sensor outputs a signal corresponding to the magnetic flux density, and the torque acting on the torsion bar is detected based on this signal.

  The fixed magnetic circuit portion includes a pair of magnetic flux collecting rings attached to the inner wall surface of the housing, and the magnetic flux collecting rings are disposed so as to face the rotating magnetic circuit portion.

  Even if the rotating magnetic circuit unit rotates together with the torsion bar and the magnetism generating unit, the magnetic flux density guided from the rotating magnetic circuit unit to each magnetism collecting ring is not changed, and the magnetic sensor works on the rotating torsion bar. Torque can be detected without contact.

Japanese Patent Laid-Open No. 2005-265587 JP 2005-345284 A JP 2007-240696 A JP 2009-244134 A

  The temperature of the torque sensor mounted on the vehicle varies greatly depending on the heat received from the engine room.

  For this reason, in the conventional torque sensor, the magnetism collecting ring is distorted due to the difference in thermal expansion between the housing and the magnetism collecting ring, and the magnetic characteristics such as permeability and coercivity of the magnetism collecting ring made of a soft magnetic material change. Therefore, there is a problem that the torque detection accuracy deteriorates.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide a non-contact type torque sensor that can suppress distortion in the magnetism collecting ring due to temperature change.

The present invention is a torque sensor for detecting a torque acting on a torsion bar, wherein a magnetism generating unit that rotates with one end of the torsion bar, a rotating magnetic circuit unit that rotates with the other end of the torsion bar, and a torsion bar that can rotate. A housing to be accommodated, a pair of magnetism collecting rings attached to the housing so as to face the rotating magnetic circuit unit, and a magnetometer (magnetic sensor) for measuring a magnetic flux density guided through each magnetism collecting ring , and a pair of magnetism collecting yoke guides the magnetic flux interposed between the magnetic flux collecting ring and the magnetic measuring device, magnetic flux collecting rings is divided into a plurality of semi-circular arc-shaped member having substantially the same, the respective this ends each other semicircular arc-shaped member is disposed apart from through the gap, magnetic flux collecting ring, which is arranged to face the respective magnetic flux collecting yoke across one respective gap It was used as a feature.

  According to the present invention, in the torque sensor, the difference in thermal expansion that occurs between the housing and the magnetism collecting ring is absorbed by increasing or decreasing the gap between the arc-shaped members, and stress and strain are generated in each arc-shaped member. Is suppressed. As a result, the torque sensor suppresses changes in magnetic properties such as the magnetic permeability and coercivity of the magnetism collecting ring with respect to temperature changes, and maintains its torque detection accuracy.

  Since the gaps of the magnetic flux collecting rings are arranged so as to face the magnetic flux collecting yokes, they are magnetically connected by the magnetic flux collecting yokes, and deterioration of the torque detection accuracy due to the magnetic gap of the gaps can be suppressed.

It is sectional drawing of the power steering apparatus which shows embodiment of this invention. It is a disassembled perspective view of a torque sensor. It is a disassembled perspective view of a torque sensor. (A) is a cross-sectional view of a fixed magnetic circuit part, (b) is a top view of a fixed magnetic circuit part. (A) is a top view of a fixed magnetic circuit part, (b) is a perspective view of a fixed magnetic circuit part. (A) is side views, such as a housing, (b) is sectional drawing which follows the AA line of the figure. (A) is a perspective view which shows the state which heat-processes a board | plate material, (b) is a top view similarly. (A) is a perspective view which shows the state which heat-processes a board | plate material as a comparative example, (b) is a top view similarly. It is sectional drawing of the housing etc. which show other embodiment.

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

(First embodiment)
1 shows an example of a power steering device 1 for a vehicle to which the present invention is applied. FIG. 1 is a cross-sectional view around the steering shaft 10 in the power steering apparatus 1.

  The steering shaft 10 includes an input shaft 11 that rotates in conjunction with a steering handle (not shown), and an output shaft 12 that rotates in conjunction with a wheel steering mechanism, and the rotation of the steering handle is used as a wheel steering mechanism. introduce. In the wheel steering mechanism, the wheel is steered when a rack shaft that meshes with a pinion (not shown) formed at the lower end of the output shaft 12 moves in the axial direction.

  Although not shown, the power steering device 1 is provided with an electric motor that is connected to the output shaft 12 as an assist mechanism for assisting the steering force of the wheel and rotationally drives a worm that meshes with the worm wheel. A steering assist torque is applied to the output shaft 12.

  Hereinafter, a specific structure of the torque sensor 2 will be described. 2 and 3 are exploded perspective views of the torque sensor 2.

  The input shaft 11 is rotatably supported by the housing 30 via a rolling bearing 37. The output shaft 12 is rotatably supported by a housing (not shown) via a rolling bearing. A sliding bearing 39 is interposed between the lower end portion of the input shaft 11 and the output shaft 12. Thereby, the input shaft 11 and the output shaft 12 are supported so as to be relatively rotatable on the same axis.

  A dust seal 36 is interposed between the housing 30 and the input shaft 11, and the inside of the housing 30 is sealed by the dust seal 36. The input shaft 11 is formed in a cylindrical shape, and a torsion bar 21 is accommodated therein.

  The torsion bar 21 has an upper end connected to the input shaft 11 via a pin (not shown) and a lower end connected to the output shaft 12 via a serration 29. As a result, the torsion bar 21 transmits the steering torque input to the input shaft 11 to the output shaft 12 and is torsionally deformed in accordance with the steering torque.

  The non-contact type torque sensor 2 is fixed to a torsion bar 21, a magnetism generating unit 22 that rotates together with the input shaft 11, a rotating magnetic circuit unit (multipolar yoke) 25 that rotates together with the output shaft 12, and a housing 30. A torsional deformation of the torsion bar 21 without contacting the steering shaft 10 is made up of a fixed magnetic circuit unit 31 provided and a magnetic sensor (magnetometer) 48 for detecting a magnetic flux density guided to the fixed magnetic circuit unit 31. The torsion angle of the torsion bar 21 is detected in accordance with the magnetic flux density that changes with this.

  In addition, it is good also as a structure which provides the magnetic generation | occurrence | production part 22 in the output shaft 12, and provides the rotary magnetic circuit part 25 in the input shaft 11. FIG.

  The magnetism generator 22 includes a back yoke (yoke) 24 fixed to the input shaft 11, and a cylindrical ring magnet 23 (multipolar magnet) fixed to the back yoke 24.

  The ring magnet 23 generates magnetism in the direction of the rotation axis O of the input shaft 11 and the torsion bar 21, and is formed by magnetizing a hard magnetic material in the direction of the rotation axis O of the input shaft 11.

  Twelve magnetic poles are formed at equal intervals in the circumferential direction on the upper end surface and the lower end surface of the cylindrical ring magnet 23, for example, six N poles and six S poles are alternately arranged.

  The cylindrical back yoke 24 is formed of a soft magnetic material and abuts on the upper end surface (magnetic pole surface) of the ring magnet 23. The back yoke 24 functions as a support member that connects the ring magnet 23 to the input shaft 11 and a yoke that connects the adjacent magnetic poles of the ring magnet 23 to guide the magnetic flux. ) To concentrate the magnetic field.

  The rotating magnetic circuit unit 25 includes a first rotating ring 26 and a second rotating ring 27 that guide the magnetic flux of the ring magnet 23.

  The rotating ring 26 and the rotating ring 27 have six magnetic path tip portions 26a and 27a facing the lower end surface (magnetic pole surface) of the ring magnet 23, and are bent from the magnetic path tip portions 26a and 27a and away from each other. Each has six magnetic path column portions extending and one magnetic path ring portion 26c, 27c extending annularly by connecting the magnetic path column portions, and these are integrally formed by pressing.

  The structures of the rotating ring 26 and the rotating ring 27 are proposed by the present applicant as Japanese Patent Application No. 2008-93636.

  The fixed magnetic circuit unit 31 includes a first magnetism collecting ring 71 and a second magnetism collecting ring 72 that are fixed to the housing 30, and a first magnetism collecting yoke 34 and a second magnetism collecting yoke 35 that are fixed to the sensor holder 40. .

  The ring-shaped magnetism collecting ring 71 and the magnetism collecting ring 72 are attached to the inner wall of the housing 30. The magnetism collecting ring 71 and the magnetism collecting ring 72 are arranged so that the inner peripheral surfaces thereof face the magnetic path ring portions 26 c and 27 c of the rotating ring 26 and the rotating ring 27.

  The magnetism collecting yoke 34, the magnetism collecting yoke 35, the magnetic sensor 48, and the substrate 47 are fixed to the resin sensor holder 40. As shown in FIG. 3, the resin sensor holder 40 is fastened to the metal housing 30 via bolts 13. An O-ring 46 is interposed between the housing 30 and the sensor holder 40, and sealing between the two is achieved.

  The block-shaped magnetism collecting yoke 34 and the magnetism collecting yoke 35 oppose the outer peripheral surfaces of the magnetism collecting ring 71 and the magnetism collecting ring 72. A pair of magnetic gaps 14 are formed as air gaps between the magnetic collecting yoke 34 and the magnetic collecting yoke 35, and a magnetic sensor 48 is interposed in each magnetic gap 14.

  For example, a Hall element is used for the magnetic sensor 48, and an output corresponding to the magnitude and direction of the magnetic field between the magnetic collecting yoke 34 and the magnetic collecting yoke 35 is taken out through the substrate 47 and the terminal. The Hall element outputs a voltage corresponding to the magnetic flux density passing therethrough as a signal through the circuit of the substrate 47. The magnetic sensor 48 may include a circuit that amplifies a Hall element signal, a circuit that performs temperature compensation, a noise filter circuit, and the like.

  The signal of the magnetic sensor 48 is sent to the controller via a terminal (not shown) provided on the sensor holder 40 and wiring connected to the terminal.

  Next, the operation of the torque sensor 2 detecting the steering torque acting on the torsion bar 21 will be described.

  In a neutral state where no torque is applied to the torsion bar 21, the magnetic path tip 26a of the rotating ring 26 and the magnetic path tip 27a of the rotating ring 27 face each other with the same area as the N pole and S pole of the ring magnet 23. Then, both are magnetically short-circuited, and the magnetic flux is not guided to the rotating magnetic circuit unit 25 and the fixed magnetic circuit unit 31.

  When the driver operates the steering handle to apply a torque in one direction to the torsion bar 21, the torsion bar 21 is torsionally deformed in accordance with the direction of the torque, and the magnetic path tip 26a of the rotating ring 26 is moved from the N pole to the S pole. While the poles face each other with a large area, the magnetic path tip 27a of the rotating ring 27 faces the N pole with a larger area than the S pole, and the magnetic flux from the ring magnet 23 is fixed to the rotating magnetic circuit part 25 and the fixed magnetism. The signal is guided to the circuit unit 31 and a signal corresponding to the strength and direction of the magnetic field is output from the magnetic sensor 48. The magnetic paths in the rotating magnetic circuit unit 25 and the fixed magnetic circuit unit 31 through which the magnetic flux is guided are: N pole → rotating ring 26 → magnetic collecting ring 71 → magnetic collecting yoke 34 → magnetic sensor 48 → magnetic collecting yoke 35 → magnetic collecting ring. 72 → rotating ring 27 → S pole.

  When the driver operates the steering handle and reverse torque acts on the torsion bar 21, the torsion bar 21 is twisted in the reverse direction, and the magnetic path tip 26a of the rotating ring 26 has a larger area than the S pole to the N pole. On the other hand, the magnetic path tip 27a of the rotating ring 27 faces with a larger area from the north pole to the south pole, and the magnetic flux is guided by a magnetic path opposite to the above magnetic path. Outputs a signal according to the strength and direction of the magnetic field. The magnetic paths in the rotating magnetic circuit unit 25 and the fixed magnetic circuit unit 31 through which the magnetic flux is guided are N pole → rotating ring 27 → magnet collecting ring 72 → magnet collecting yoke 35 → magnetism sensor 48 → magnet collecting yoke 34 → magnet collecting ring. 71 → rotating ring 26 → S pole.

  When the torsion bar 21 is twisted and deformed in accordance with the torque acting on the torsion bar 21 in this way, and the area difference between the magnetic path tip 27a of the rotating ring 26 and the rotating ring 27 is opposite to the N pole and S pole of the ring magnet 23, The magnetic flux density guided to the magnetic sensor 48 increases, and a signal corresponding to this torque is output from the magnetic sensor 48.

  The number of magnetic poles formed on one end surface of the ring magnet 23 is arbitrarily set within a range of 2 or more. The magnetic flux density guided to the magnetic sensor 48 can be increased by increasing the number of magnetic poles under the condition that the areas of the rotating ring 26 and the rotating ring 27 facing the ring magnet 23 are the same.

  Hereinafter, the configuration of the fixed magnetic circuit unit 31 will be described in detail.

  The fixed magnetic circuit unit 31 includes a magnetism collecting ring 71 and a magnetism collecting ring 72 that are fixed to the housing 30, and a magnetism collecting yoke 34 and a magnetism collecting yoke 35 that are fixed to the sensor holder 40.

  The ring-shaped magnetism collecting ring 71 and the magnetism collecting ring 72 are attached to the inner wall of the housing 30. The magnetism collecting ring 71 and the magnetism collecting ring 72 are arranged so that the inner peripheral surfaces thereof face the magnetic path ring portions 26 c and 27 c of the rotating ring 26 and the rotating ring 27.

  4A is a cross-sectional view of the housing 30 and the sensor holder 40 in which the fixed magnetic circuit unit 31 is interposed, and FIG. 4B is a magnetism collecting ring 71 and the sensor holder 40 constituting the fixed magnetic circuit unit 31. FIG. 5A is a plan view of the magnetism collecting ring 71, the magnetism collecting yoke 34, and the magnetic sensor 48 constituting the fixed magnetic circuit section 31, and FIG. 5B is a magnetism collecting rings 71 and 72, the magnetism collecting yoke 34, 35 is a perspective view of the magnetic sensor 48. FIG.

  The magnetism collecting rings 71 and 72 are formed in a cylindrical ring shape, and face the magnetic path ring portions 26c and 27c of the rotating rings 26 and 27 of the rotating magnetic circuit portion 25 with an annular gap.

  The magnetic collecting yokes 34 and 35 are formed in a block shape facing the outer peripheral surfaces of the magnetic collecting rings 71 and 72. The magnetic flux collecting yokes 34 and 35 have a magnetic flux collecting ring facing portion 49 facing the outer peripheral surfaces of the magnetic flux collecting rings 71 and 72, and a pair of magnetic sensor facing portions 50 facing the pair of magnetic sensors 48.

  6A is a side view of the housing 30 and the like, and FIG. 6B is a cross-sectional view taken along the line AA in FIG. The housing 30 includes a mounting seat 53 to which the sensor holder 40 is attached, and a circular sensor opening 54 that opens in the mounting seat 53.

  In the opening 54 for the sensor of the housing 30, a facing portion 73 for the magnetic collecting yoke that faces the magnetic collecting yokes 34 and 35 of the magnetic collecting rings 71 and 72 faces.

  As shown in FIG. 3, the sensor holder 40 includes a flange portion 57 that is fastened to the mounting seat 53 via the bolt 13, and a cylindrical surface fitting portion 56 that fits into the sensor opening 54 of the housing 30. Have A facing portion 49 for the magnetism collecting ring of the magnetism collecting yokes 34 and 35 provided inside the fitting portion 56 faces the sensor opening portion 54 of the housing 30.

  As shown in FIGS. 4A and 4B, in the state where the sensor holder 40 is assembled to the housing 30, the magnetic flux collecting yokes 34 and 35 are opposed to the magnetic flux collecting rings at the sensor opening 54 of the housing 30. The part 49 and the opposing part 73 for the magnetism collecting yokes of the magnetism collecting rings 71 and 72 are in contact with each other. As a result, the magnetic flux collecting rings 71 and 72 constitute a magnetic circuit that guides the magnetic flux to the magnetic sensor 48 via the magnetic flux collecting yokes 34 and 35.

  As shown in FIGS. 5A and 5B, the cylindrical (annular) magnetism collecting rings 71 and 72 are divided into two arc-shaped members 70.

  The two arc-shaped members 70 constituting the magnetism collecting rings 71 and 72 are curved in a semicircular arc shape around the rotation axis O of the steering shaft 10 and are formed in the same shape.

  The magnetism collecting rings 71 and 72 and the magnetism collecting yokes 34 and 35 are formed of a soft magnetic material made of permalloy (nickel-iron alloy) or the like.

The magnetism collecting rings 71 and 72 are manufactured by sequentially performing the following steps.
(1). A cutting process in which a flat plate material is punched from a soft magnetic base material.
(2). A press molding process in which the punched plate material is press-molded to form an arc-shaped member 70 curved in an arc shape.
(3). A heat treatment step of heat treating the press-formed arcuate member 70.
(4). An assembling step for assembling the magnetic flux collecting rings 71 and 72 by arranging two arcuate members 70 in a ring shape.

  In the cutting step (1) and the press forming step (2), stress and strain are generated in the arc-shaped member 70 that is press-formed after being cut. The soft magnetic material of the arc-shaped member 70 changes its magnetic characteristics due to stress and strain, and the magnetic permeability is reduced and the coercive force is increased.

  In the heat treatment step (3), the arc-shaped member 70 press-molded is carried into the heat treatment furnace, and the heat treatment furnace is heated to a predetermined temperature (for example, about 1300 ° C.) after being set to a hydrogen atmosphere or a vacuum atmosphere. Is maintained for a predetermined time (for example, 2 to 3 hours), and then the arc-shaped member 70 is carried out of the heat treatment furnace.

  The arc-shaped member 70 is heat-treated in this manner, so that stress and distortion generated during press molding are eliminated, and desired magnetic permeability and coercive force are obtained.

  FIGS. 7A and 7B are a perspective view and a plan view showing a state in which a plurality of arc-shaped members 70 are arranged in a heat treatment furnace. The arcuate member 70 is placed so that the planar end surface abuts on a table in the heat treatment furnace.

  The semicircular arc-shaped members 70 arranged along the row are arranged so as to approach each other without being in contact with each other by being arranged in the same direction.

  8A and 8B are a perspective view and a plan view showing a state in which the annular soft magnetic members 100 cut out at one place are arranged as a comparative example.

  As shown in FIG. 7, the arc-shaped members 70 (workpieces) press-molded in a semicircular arc shape (semi-annular shape) are arranged so that adjacent ones overlap each other in the plane direction. Compared to the arrangement of the soft magnetic members 100, the number of workpieces carried into the heat treatment furnace is greatly increased, and the cost required for the heat treatment can be reduced.

  Hereinafter, the assembly process (4) will be described.

  As shown in FIGS. 4A and 6B, a resin case 80 interposed between the inner walls of the metal housing 30 is provided, and magnetism collecting rings 71 and 72 are provided on the inner wall of the case 80. It is attached.

  The case 80 is formed in a cylindrical shape with a part thereof cut away. The case 80 has an opening 84 cut out so as to engage with the sensor opening 54.

  A groove 45 for receiving the case 80 is formed in the housing 30, and the case 80 is fitted into the groove 45 and fixed.

  The case 80 is integrally formed by injection molding synthetic resin, and metal magnetism collecting rings 71 and 72 are embedded by insert molding.

Hereinafter, a procedure for injection molding the case 80 using a mold facility (not shown) will be described.
1. First, the semicircular arc-shaped members 70 constituting the magnetism collecting rings 71 and 72 are installed in the mold.
2. Molten resin is filled in the mold, and each arc-shaped member 70 is insert-molded in the case 80.
3. The molded case 80 is removed from the mold.

  Metal magnetism collecting rings 71 and 72 are embedded in the resin case 80 through the above steps. The case 80 has grooves 81 and 82 in which the magnetism collecting rings 71 and 72 are embedded.

  In a state where the magnetism collecting rings 71 and 72 are embedded in the case 80, the two arc-shaped members 70 are arranged so that the respective end portions are separated from each other, and two gaps are provided between the respective end portions. 74, 75 are provided.

  The magnetic flux collecting rings 71 and 72 are assembled to the housing 30 so that one gap 74 faces the magnetic flux collecting yokes 34 and 35.

  On the plan view shown in FIG. 5A, one gap 74 is disposed so as to face the central portion of the confronting portion 49 for the magnetism collecting ring of the magnetism collecting yokes 34 and 35.

  The other gap 75 is located on the opposite side of the housing 30 from the sensor opening 54 and is farthest from the magnetism collecting yokes 34 and 35. Thereby, the magnetic flux guided to the magnetic collecting yokes 34 and 35 through the magnetic collecting rings 71 and 72 does not pass through the gap 75. For this reason, by providing the gap 75, it is avoided that the magnetic flux density guided to the magnetic collecting yokes 34 and 35 through the magnetic collecting rings 71 and 72 is lowered.

  When the magnetism collecting ring is divided into, for example, three or more arc-shaped members, a gap is provided in the path through which the magnetic flux guided to the magnet collecting yoke through the magnetism collecting ring is provided. As a result, the magnetic flux density guided to the magnetic collecting yoke 5 through the magnetic collecting ring is reduced. In order to cope with this, it is necessary to make the gap arranged in the path through which the magnetic flux passes as small as possible.

  The gap (gap width) of the gap 75 is formed smaller than the gap 74.

  As described above, in the torque sensor 2, the annular magnetism collecting rings 71 and 72 assembled to the housing 30 (case 80) are divided into a plurality (two) of arc-shaped members 70. The end portions are arranged in a state of being spaced apart via the gaps 74 and 75, and one gap 74 is arranged to face the magnetism collecting yokes 34 and 35.

  The temperature of the torque sensor 2 mounted on the vehicle changes due to heat received from the engine room, and a difference in thermal expansion occurs between the housing 30 (case 80) and the magnetism collecting rings 71 and 72.

  In the torque sensor 2, the difference in thermal expansion that occurs between the housing 30 (case 80) and the magnetism collecting rings 71 and 72 is absorbed by the increase and decrease of the gaps 74 and 75 of each arcuate member 70, and each arcuate shape. The occurrence of stress and strain in the member 70 is suppressed. Thereby, the torque sensor 2 is restrained from changing magnetic characteristics such as the magnetic permeability and coercivity of the magnetism collecting rings 71 and 72 due to the temperature change, and the torque detection accuracy is maintained.

  Since the magnetism collecting rings 71 and 72 are formed separately from the magnetism collecting yokes 34 and 35, the shape of each arc member 70 is simplified, and stress and distortion are generated in each arc member 70. It can be suppressed.

  Further, since the gap 74 between the magnetism collecting rings 71 and 72 is disposed so as to face the magnetism collecting yokes 34 and 35, it is magnetically coupled by the magnetism collecting yokes 34 and 35, and torque is detected by the magnetic gap of the gap 74. Deterioration in accuracy can be suppressed.

  Further, the structure in which the magnetic flux collecting rings 71 and 72 are provided opposite to the magnetic flux collecting yokes 34 and 35 eliminates the need to replace the magnetic flux collecting rings 71 and 72 when the magnetic sensor 48 or the like fails, for example. The magnetic yokes 34 and 35 can be easily exchanged together.

In the present embodiment, a pair of magnetic sensors 48 are provided between the magnetism collecting yokes 34 and 35 , and even if one of the magnetic sensors 48 fails, the torque of the torque sensor 2 is detected by the other magnetic sensor 48, Fail-safe function is fulfilled. The torque sensor 2 is not limited to this, and it is possible to simplify the structure by providing a single magnetic sensor 48 between the magnetism collecting yokes 34 and 35 .

  In the present embodiment, a resin case 80 interposed in the metal housing 30 is provided, and the arc-shaped member 70 is embedded in the case 80 by insert molding.

  Based on the above configuration, the volume change of the synthetic resin that occurs when the synthetic resin is cured when the arc-shaped member 70 is insert-molded into the case 80 is absorbed by the gaps 74 and 75 between the arc-shaped members 70 being reduced. The occurrence of stress and distortion in each arcuate member 70 can be suppressed. Thereby, since the magnetic characteristics of the magnetism collecting rings 71 and 72 do not change significantly when the arc-shaped member 70 is insert-molded in the case 80, the torque sensor 2 can suppress the change in magnetic flux guided to the magnetic sensor 48 and reduce the torque. Detection accuracy is maintained.

  Since the magnetism collecting rings 71 and 72 are assembled to the metal housing 30 via the resin case 80, excessive deformation of the magnetism collecting rings 71 and 72 at the time of assembling is suppressed by the resin case 80. , 72 is restrained from generating stress and strain.

(Second Embodiment)
Next, another embodiment shown in FIG. 9 will be described. FIG. 9 is a sectional view of the housing 30 and the like. This has basically the same configuration as the embodiment of FIGS. 1 to 7, and only the differences will be described. In addition, the same code | symbol is attached | subjected to the same structure part as the said embodiment.

  In the present embodiment, the resin case 80 in the above embodiment is eliminated, and grooves 41 and 42 in which the magnetic flux collecting rings 71 and 72 are received are formed on the inner wall of the housing 30. The magnetic flux collecting rings 71 and 72 are formed in the grooves 41 and 42. Are fitted.

  As an assembling step (4), a caulking tool that drives the inner wall surface 43 of the housing 30 and deforms the side edges of the grooves 41 and 42 to form the caulking portions that fix the magnetism collecting rings 71 and 72 is formed.

  The magnetism collecting rings 71 and 72 are fixed to the housing 30 in the rotation axis direction and the rotation radial direction by the caulking portion, and are prevented from rotating, so that sufficient fixing strength is obtained.

Regarding the structure in which the magnetism collecting ring 71 and the magnetism collecting ring 72 are caulked and fixed to the inner wall of the housing 30, Japanese Patent Application No. 2008-91838 (
Japanese Laid-Open Patent Publication No. 2009-244134).

  Also in this case, the torque sensor 2 has a configuration in which the magnetism collecting rings 71 and 72 are divided into two arc-shaped members 70, so that the thermal expansion difference generated between the housing 30 and the magnetism collecting rings 71 and 72 is different for each circle. It is absorbed when the gaps 74 and 75 of the arcuate member 70 increase or decrease, and the occurrence of stress and strain in the soft magnetic body of each arcuate member 70 is suppressed.

  When the magnetism collecting rings 71 and 72 are fitted into the grooves 41 and 42, the magnetism collecting rings 71 and 72 are divided into two arcuate members 70. , 42 to prevent the magnetic flux collecting rings 71, 72 from being stressed or distorted.

  As still another embodiment, the magnetism collecting rings 71 and 72 may be divided into three or more arc-shaped members 70.

  The present invention is not limited to the above-described embodiment, and it is obvious that various modifications can be made within the scope of the technical idea.

2 Torque sensor 21 Torsion bar 22 Magnetic generating unit 25 Rotating magnetic circuit unit 30 Housing 31 Fixed magnetic circuit unit 34, 35 Magnetic collecting yoke 48 Magnetic sensor 70 Arc-shaped member 71 Magnetic collecting ring 72 Magnetic collecting ring 74, 75 Clearance 80 Case

Claims (3)

A torque sensor for detecting a torque acting on the torsion bar,
A magnetic generator that rotates with one end of the torsion bar;
A rotating magnetic circuit that rotates with the other end of the torsion bar;
A housing in which the torsion bar is rotatably accommodated;
A pair of magnetism collecting rings attached to the housing so as to face the rotating magnetic circuit portion;
A magnetometer for measuring the magnetic flux density guided through each magnetism collecting ring;
A pair of magnetic flux collecting yokes that are interposed between the magnetic flux collecting rings and the magnetic measuring device to guide the magnetic flux and are separate from the magnetic flux collecting rings ,
The magnetic flux collecting rings is divided into two half arcuate member of substantially the same, the ends each other of these two half arcuate member is disposed apart from through the gap,
Each said magnetism collection ring is arrange | positioned so that each said magnetism collection yoke may face across one of the said each clearance gaps, The torque sensor characterized by the above-mentioned. A resin sensor holder fixed to the housing;
The semicircular arc member is attached to the housing;
The torque sensor according to claim 1 , wherein the magnetism collecting yoke is fixed to the resin sensor holder . A resin case interposed in the housing;
The torque sensor according to claim 1 or 2, wherein the semicircular arc member is embedded in the case by insert molding.

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