JP2012251814A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To secure an opposition area between yokes which constitute a magnetic flux transmission path of a torque sensor using a single-pole magnet.SOLUTION: A torque sensor 3 comprises: a torsion bar 13 which couples an input shaft 11 and an output shaft 12 coaxially with each other; a magnet 2Z and an N/S pole yoke 3A, 3B fixed to the input shaft 11; a pair of intermediate yokes 4A, 4B fixed to the output shaft 12; magnetic collecting yokes 5A, 5B which collect magnetic flux from the pair of intermediate yokes 4A, 4B; and a magnetic sensor 6 which detects magnetic flux density. The magnet 2Z is magnetized to have an N pole and an S pole in an axial direction. The N/S pole yokes 3A, 4B fitted to the magnet 2Z have a plurality of claws projecting radially outward, and the intermediate yokes 4A, 4B have a plurality of claws projecting radially inward. When the torsion bar 13 is twisted and displaced, the claws of the N/S pole yokes 3A, 3B and the claws of the intermediate yokes 4A, 4B overlap in the axial direction to effectively secure the opposition area.

Description

  The present invention relates to a torque sensor that detects an axial torque applied to a rotating shaft as a change in magnetic flux density (magnetic field strength).

  Conventionally, a torque sensor for detecting shaft torque in an electric power steering device or the like is known. For example, the torque sensor described in Patent Document 1 uses a “multipolar magnet” in which a plurality of N poles and S poles are alternately magnetized in the circumferential direction. When the torsion bar connecting the input shaft and the output shaft is twisted, the magnetic flux generated in the pair of magnetic yokes is detected by the change in the relative position in the circumferential direction between the multipole magnet and the pair of magnetic yokes. As a result, the shaft torque is detected.

  On the other hand, the torque sensors of Patent Documents 2 to 4 use “single-pole magnets” in which one of the axial directions is N pole and the other is S pole. The torque sensor of Patent Document 5 uses a “single-pole magnet” in which the radially outer side and the inner side are magnetized to the N pole and the S pole. Monopole magnets require fewer man-hours than multipole magnets.

JP 2003-149062 A JP 2008-216019 A JP 2008-203176 A JP 2005-308443 A JP 2005-265539 A

  In the torque sensor of Patent Document 2, the path from the “magnet side magnetic bodies 11A and 11B” positioned relatively inside in the radial direction to the “magnetic body portion 6” positioned relatively outside in the radial direction is magnetic flux transmission. It becomes a route. Here, the outermost diameter of the “magnet side magnetic bodies 11A, 11B” is smaller than the outermost inner diameter of the “magnetic body portion 6”. Therefore, the “magnet side magnetic bodies 11A and 11B” and the “magnetic body portion 6” do not overlap in the axial direction regardless of the relative rotational position. In other words, “the convex portions 6AY and 6BY of the magnetic body” are such that the axial surface having a relatively large area does not face the “magnet side magnetic bodies 11A and 11B”, and only the end surface on the inner side of the relatively small area. Is opposed to the “magnet side magnetic bodies 11A, 11B”. Therefore, there is a problem that the magnetic flux is not effectively transmitted. Moreover, the torque sensor of patent document 3 is the same structure as the torque sensor of patent document 2, and has the same problem.

  In addition, the torque sensor disclosed in Patent Document 4 includes “a rotor 70 configured by magnetic cores 71 and 72” located on the inner side in the radial direction and “magnetic cores 81 and 82 positioned on the outer side in the radial direction. The tooth profile protrusions 74 and 75 and the tooth profile protrusions 84 and 85 having a relatively large area face each other. However, in reality, it is considered that the magnetic field cancels out between the tooth-shaped protrusions of different polarities adjacent to each other, and sufficient magnetic flux cannot be generated.

Furthermore, since the torque sensor of Patent Document 5 has four magnetic flux transmission paths in the radial direction arranged side by side in the axial direction, the size of the torque sensor increases.
The present invention was created in view of the above points, and the purpose of the present invention is to provide a torque sensor that uses a monopolar magnet, and to increase the opposing area of yokes that constitute a magnetic flux transmission path without increasing the size of the body. It is to secure.

A torque sensor according to claims 1 to 8 includes a torsion bar, a magnet, a set of magnet end yokes, a set of intermediate yokes, and a magnetic sensor. The torsion bar connects the first shaft and the second shaft coaxially, and converts the torque applied between the first shaft and the second shaft into a torsional displacement.
Further, the torque sensor according to claims 1 to 3 and the torque sensor according to claims 4 to 6 have technical characteristics relating to the relative positions of the magnet, the set of magnet end yokes, and the set of intermediate yokes. The “axial direction” and the “radial direction” have a corresponding relationship. Details will be described below.

First, in the torque sensor according to the first to third aspects, the magnet is fixed to one end side of the first shaft or the torsion bar, and is magnetized to the N pole and the S pole in the “axial direction”. That is, this magnet is a monopolar magnet composed of two poles.
The set of magnet end yokes includes an N pole yoke connected to the N pole of the magnet and an S pole yoke connected to the S pole of the magnet. The N pole yoke and the S pole yoke have a plurality of claws protruding radially outward at equal intervals in the circumferential direction. The claws of the N pole yoke and the claws of the S pole yoke are alternately arranged with a shift in the circumferential direction.

The set of intermediate yokes includes a first intermediate yoke and a second intermediate yoke that are fixed to the second shaft or the other end side of the torsion bar outside the diameter of the set of magnet end yokes and are spaced apart from each other. The set of magnet end yokes forms a magnetic circuit together with the set of magnet end yokes, and the magnetic flux density generated in the magnetic circuit changes when it rotates relative to the set of magnet end yokes according to torsion of the torsion bar. .
The magnetic sensor detects the magnetic flux density generated in the magnetic circuit.
When the pair of intermediate yokes rotate relative to the pair of magnet end yokes, at least a portion thereof overlaps with the claws of the pair of magnet end yokes in the axial projection.
With this configuration, it is possible to effectively ensure a facing area between the set of magnet end yokes and the set of intermediate yokes that constitute the magnetic flux transmission path without increasing the size of the torque sensor.

According to the second aspect of the present invention, the first intermediate yoke and the second intermediate yoke have a plurality of claws protruding radially inward at equal intervals in the circumferential direction. The pawls of the first intermediate yoke and the pawls of the second intermediate yoke are alternately arranged in the circumferential direction.
Specifically, each of the first intermediate yoke and the second intermediate yoke includes a ring portion and a plurality of claws protruding from the ring portion. The plurality of claws may extend directly in the radially inward direction from the ring part, or may be bent in the radially inward direction once extending in the axial direction from the ring part.

When the relative rotation position of the pair of magnet end yokes and the pair of intermediate yokes is a predetermined position, one of the N pole yoke or the S pole yoke, the first intermediate yoke hook, the N pole yoke or the S pole The other claw of the yoke and the claw of the second intermediate yoke are alternately arranged in this order in the circumferential direction.
When a pair of intermediate yokes rotate relative to a set of magnet end yokes from a predetermined position, the pair of magnet end yoke claws and the pair of intermediate yoke claws overlap "in axial projection". .
This specifically shows a configuration for “effectively ensuring the facing area between the set of magnet end yokes and the set of intermediate yokes”.

  According to the third aspect of the present invention, the claws of the first intermediate yoke and the second intermediate yoke are arranged at the neutral point so that the magnetic flux generated in the magnetic circuit becomes zero at the neutral point where the torsional displacement of the torsion bar is zero. The claws are arranged so as to be shifted with respect to the intermediate position between the claws of the N pole yoke and the S pole yoke.

A case is assumed in which the claws of the first intermediate yoke and the second intermediate yoke are arranged at an intermediate position between the claws of the N pole yoke and the S pole yoke at the neutral point where the torsional displacement is zero.
At this time, the magnetic flux from the claws of the N pole yoke to the claws of the first intermediate yoke and the magnetic flux from the claws of the N pole yoke to the claws of the second intermediate yoke are substantially canceled. Similarly, the magnetic flux from the first intermediate yoke claw to the south pole yoke claw and the magnetic flux from the second intermediate yoke claw to the south pole yoke claw are substantially canceled.

However, since the magnetic flux from the N pole side of the magnet to the S pole side is fundamentally generated, the magnetic sensor is transmitted from the N pole of the magnet to the intermediate yoke via the N pole yoke and from the intermediate yoke to the S pole. A magnetic flux is generated that returns to the south pole of the magnet via the pole yoke. That is, according to the torsional displacement of the torsion bar, the magnetic flux density changes in the positive and negative directions not based on zero but on the basis of the magnetic flux density at the offset neutral point. In this case, there is a possibility that a linear region in which the magnetic flux density changes linearly with respect to the rotation angle (twisted displacement) cannot be obtained sufficiently.
Therefore, if the magnetic flux generated in the magnetic circuit becomes zero at the neutral point according to the configuration of the third aspect, the magnetic flux density detected according to the torsional displacement of the torsion bar changes around zero. The linear region of density can be extended.

Next, in the torque sensor according to the fourth to sixth aspects, the magnet is fixed to one end of the first shaft or the torsion bar, and is magnetized to the N pole and the S pole in the “radial direction”. That is, this magnet is a monopolar magnet composed of two poles.
The set of magnet end yokes includes an outer pole yoke connected to the magnetic pole on the outer diameter side of the magnet and an inner pole yoke connected to the magnetic pole on the inner diameter side of the magnet. The outer pole yoke and the inner pole yoke have a plurality of claws protruding on one side in the axial direction at equal intervals in the circumferential direction. The claws of the outer pole yoke and the claws of the inner pole yoke are alternately arranged in the circumferential direction.

The pair of intermediate yokes are fixed to the other end side of the second shaft or the torsion bar on the side where the claws of the pair of magnet end yokes in the axial direction protrude, and are separated from each other. Consists of. The pair of intermediate yokes form a magnetic circuit together with the pair of magnet end yokes, and the magnetic flux density generated in the magnetic circuit changes when the pair of intermediate yokes rotate relative to the pair of magnet end yokes according to torsion of the torsion bar.
The magnetic sensor detects the magnetic flux density generated in the magnetic circuit.
When the pair of intermediate yokes are rotated relative to the pair of magnet end yokes, at least a portion thereof overlaps with the claws of the pair of magnet end yokes in the radial projection.
With this configuration, it is possible to effectively ensure a facing area between the set of magnet end yokes and the set of intermediate yokes that form the magnetic flux transmission path.

According to the fifth aspect of the present invention, the first intermediate yoke and the second intermediate yoke have a plurality of claws protruding in the axial direction toward the magnet at equal intervals in the circumferential direction. The claws of the second intermediate yoke are alternately arranged in the circumferential direction.
Specifically, each of the first intermediate yoke and the second intermediate yoke includes a ring portion and a plurality of claws protruding from the ring portion. The plurality of claws may extend directly from the ring portion in the axial direction, or may extend from the ring portion in the radial direction and then bend in the axial direction.

When the position of relative rotation between the pair of magnet end yokes and the pair of intermediate yokes is a predetermined position, one of the outer pole yoke or the inner pole yoke, the first intermediate yoke claw, the outer pole yoke or the inner pole The other claw of the yoke and the claw of the second intermediate yoke are alternately arranged in this order in the circumferential direction.
When a pair of intermediate yokes rotate relative to a set of magnet end yokes from a predetermined position, the pair of magnet end yoke claws overlap with the pair of intermediate yoke claws "in radial projection" .
Thus, similarly to the second aspect of the invention, a configuration for “effectively ensuring the facing area between the set of magnet end yokes and the set of intermediate yokes” is specifically shown.

According to the sixth aspect of the present invention, the claws of the first intermediate yoke and the second intermediate yoke are arranged at the neutral point so that the magnetic flux generated in the magnetic circuit is zero at the neutral point where the torsional displacement of the torsion bar is zero. The claws are arranged so as to be shifted with respect to an intermediate position between the claws of the outer pole yoke and the inner pole yoke.
As a result, as in the third aspect of the invention, the linear region of the magnetic flux density detected in accordance with the torsional displacement of the torsion bar can be extended.

According to the seventh aspect of the present invention, the magnet and the magnet end yoke are formed by being divided in the circumferential direction.
By forming the magnet and the magnet end yoke, for example, by dividing the magnet and the magnet end yoke into 4 to 8 parts in the circumferential direction, it becomes easy to manufacture parts. Further, as compared with the case where the torsion bar is inserted through the annular magnet and the magnet end yoke, the divided magnets and the magnet end yoke can be attached from the radially outward direction of the torsion bar, so that the assembling property is improved.

The torque sensor according to an eighth aspect includes a pair of magnetism collecting yokes. The set of magnetic flux collecting yokes faces the set of intermediate yokes in the axial direction or the radial direction, and collects magnetic flux from the set of intermediate yokes. The magnetic sensor is provided between the pair of magnetic collecting yokes and detects the magnetic flux density of the magnetic flux collected by the pair of magnetic collecting yokes.
Thereby, the magnetic flux of a magnetic circuit can be detected efficiently.

1 is an exploded perspective view of a torque sensor according to a first embodiment of the present invention. 1 is a schematic configuration diagram of an electric power steering apparatus to which a torque sensor according to a first embodiment of the present invention is applied. It is a perspective view of the detection part of the torque sensor by a 1st embodiment of the present invention. It is the (a) plane schematic diagram and (b) side surface schematic diagram of the detection part explaining the operation | movement of the torque sensor by 1st Embodiment of this invention. It is the (a) plane schematic diagram and (b) side surface schematic diagram of the detection part explaining the operation | movement of the torque sensor by 1st Embodiment of this invention. It is the (a) plane schematic diagram and (b) side surface schematic diagram of the detection part explaining the operation | movement of the torque sensor by 1st Embodiment of this invention. It is a plane schematic diagram of the detection part of the torque sensor by 2nd Embodiment of this invention. It is a characteristic view which shows the relationship between the rotation angle and magnetic flux density of the torque sensor by (a) 1st Embodiment of this invention, and (b) 2nd Embodiment. It is a plane schematic diagram of the detection part of the torque sensor by 3rd Embodiment of this invention. It is a perspective view of the detection part of the torque sensor by a 4th embodiment of the present invention. It is the (a) plane schematic diagram and (b) side surface schematic diagram of the detection part of the torque sensor by 4th Embodiment of this invention. It is a cross-sectional schematic diagram of the detection part explaining operation | movement of the torque sensor by 4th Embodiment of this invention. It is a cross-sectional schematic diagram of the detection part explaining operation | movement of the torque sensor by 4th Embodiment of this invention. (A): It is a plane schematic diagram of the detection part of the torque sensor by 5th Embodiment of this invention. (B): It is a plane schematic diagram of the detection part of the torque sensor by 6th Embodiment of this invention.

Hereinafter, torque sensors according to a plurality of embodiments of the present invention will be described with reference to the drawings.
(First embodiment)
As shown in FIG. 2, the torque sensor 3 according to the first embodiment of the present invention is applied to, for example, an electric power steering apparatus for assisting a steering operation of a vehicle.

  FIG. 2 shows an overall configuration of a steering system including the electric power steering device 90. A steering shaft 92 connected to the handle 91 is provided with a torque sensor 3 for detecting a steering torque. A pinion gear 96 is provided at the tip of the steering shaft 92, and the pinion gear 96 meshes with the rack shaft 97. A pair of wheels 98 are rotatably connected to both ends of the rack shaft 97 via tie rods or the like. The rotational motion of the steering shaft 92 is converted into a linear motion of the rack shaft 97 by the pinion gear 96, and the set of wheels 98 is steered.

  The torque sensor 3 is provided between the input shaft 11 and the output shaft 12 constituting the steering shaft 92, detects the steering torque applied to the steering shaft 92, and outputs the detected steering torque to the ECU 93. The ECU 93 controls the output of the electric motor 94 according to the detected steering torque. The steering assist torque generated by the electric motor 94 is decelerated via the reduction gear 95 and transmitted to the steering shaft 92.

Next, the configuration of the torque sensor 3 will be described with reference to FIGS. In the following description, the upper direction in FIGS. 1 and 3 will be described as “up”, and the lower direction in FIGS. 1 and 3 will be described as “down”.
As shown in FIG. 1, the torque sensor 3 includes a torsion bar 13 and a detection unit 201. One end side of the torsion bar 13 is fixed to the input shaft 11 as a “first axis”, and the other end side is fixed to an output shaft 12 as a “second axis” by a fixing pin 15. 12 are connected on the same axis. The torsion bar 13 is a rod-like elastic member, and converts the steering torque applied to the steering shaft 92 into a torsional displacement.

The detection unit 201 includes a magnet 2Z, an N pole yoke 3A and an S pole yoke 3B (hereinafter collectively referred to as “N / S pole yokes 3A and 3B”), “one set of magnet end yokes”, and “one. The first intermediate yoke 4A and the second intermediate yoke 4B as “a set of intermediate yokes”, the first magnetic collection yoke 5A and the second magnetic collection yoke 5B as “a set of magnetic collection yokes”, and the magnetic sensor 6. The
The magnet 2Z is a single-pole magnet fixed to the input shaft 11 and magnetized in the “axial direction” on the N pole and the S pole. In this embodiment, the input shaft 11 (upper) side is magnetized to the N pole, and the output shaft 12 (lower) side is magnetized to the S pole.

The N pole yoke 3A is connected to the N pole of the magnet 2Z, and the S pole yoke 3B is connected to the S pole of the magnet 2Z.
The N / S pole yokes 3A and 3B have a plurality of claws 31A and 31B protruding radially outward from the ring portions 30A and 30B at equal intervals in the circumferential direction. Further, the N pole yoke pawls 31A and the S pole yoke pawls 31B are alternately arranged in the circumferential direction. In this embodiment, the N pole yoke 3A and the S pole yoke 3B have eight claws 31A and 31B at 45 ° intervals, respectively. The claw 31A of the N pole yoke and the claw 31B of the S pole yoke are They are alternately arranged with a shift of 22.5 ° from each other (see FIG. 4).

The first intermediate yoke 4A and the second intermediate yoke 4B are fixed to the output shaft 12 outside the diameter of the N / S pole yokes 3A and 3B, and are separated from each other. The intermediate yokes 4A and 4B form a magnetic circuit together with the magnet 2Z and the N / S pole yokes 3A and 3B. When the relative position with the N / S pole yokes 3A and 3B changes according to the twist of the torsion bar 13, the magnetic flux density generated in the magnetic circuit changes.
The intermediate yokes 4A, 4B have a plurality of claws 41A, 41B protruding from the ring portions 40A, 40B in the radially inward direction at equal intervals in the circumferential direction. Further, the claws 41A of the first intermediate yoke and the claws 41B of the second intermediate yoke are alternately arranged in the circumferential direction.

  In the present embodiment, the first intermediate yoke 4A is provided on the upper side in the axial direction, and the second intermediate yoke 4B is provided on the lower side in the axial direction. The first intermediate yoke 4A and the second intermediate yoke 4B have eight claws 41A and 41B at 45 ° intervals, respectively. The claw 41A of the first intermediate yoke extends once downward in the axial direction from the ring portion 40A and then bends radially inward. The claw 41B of the second intermediate yoke extends once in the axial direction upward from the ring portion 40B and then bends in the radially inward direction. Further, the claws 41A of the first intermediate yoke and the claws 41B of the second intermediate yoke are alternately arranged with a shift of 22.5 ° from each other.

The first magnetic flux collecting yoke 5A is provided on the axially upper side of the first intermediate yoke 4A along a part of the ring portion 40A of the first intermediate yoke 4A in the circumferential direction (about 120 ° in the present embodiment). The second magnetism collecting yoke 5B is provided on the lower side in the axial direction of the second intermediate yoke 4B along a part in the circumferential direction of the ring portion 40B of the second intermediate yoke 4B. The magnetic collecting yokes 5A and 5B face the intermediate yokes 4A and 4B in the axial direction, and collect magnetic flux from the intermediate yokes 4A and 4B.
The magnetic sensor 6 is provided between the first magnetism collecting yoke 5A and the second magnetism collecting yoke 5B, detects the magnetic flux density collected by the magnetism collecting yokes 5A, 5B, converts it into a voltage signal, and outputs it. Specifically, a Hall element, a magnetoresistive element, or the like can be used as the magnetic sensor 6.

Next, the operation of the detection unit 201 will be described with reference to FIGS. Each of FIGS. 4A to 6A is a schematic plan view of the detection unit 201 viewed from the input shaft 11 side. Each of FIG. 4B is a schematic side view of the detection unit 201 viewed from the side. is there.
In each figure (a), the entire upper surface of the N pole yoke 3A is shown around the central axis O. The magnet 2Z and the S pole yoke 3B overlap the lower side (the other side of the drawing) of the N pole yoke 3A, and only the claw 31B of the S pole yoke 3B is visible. Further, a first intermediate yoke 4A and a first magnetism collecting yoke 5A are shown in the radially outward direction of the N pole yoke 3A. The ring portion 40B of the second intermediate yoke 4B overlaps the other side of the ring portion 40A of the first intermediate yoke 4A, and only the claw 41B of the second intermediate yoke 4B is visible.

Each figure (b) exaggerates and shows the axial direction (up-down direction of a figure). The magnet 2Z and the N / S pole yokes 3A, 3B are fixed to the input shaft 11 side of the torsion bar 13, and the intermediate yokes 4A, 4B are fixed to the output shaft 12 side of the torsion bar 13.
4 to 6, the position in the rotation direction of the input shaft 11 side, that is, the magnet 2Z and the N / S pole yokes 3A and 3B is fixed, and the output shaft 12 side, that is, the intermediate yokes 4A and 4B are fixed to the magnet 2Z and the N / S pole. The state rotated relative to the yokes 3A and 3B is shown.

  First, FIG. 4 shows a neutral point state in which no steering torque is applied between the input shaft 11 and the output shaft 12 and no torsional displacement occurs in the torsion bar 13. Here, of the intermediate positions between the N pole yoke claw 31A and the S pole yoke claw 31B, the position on the counterclockwise side of the drawing with respect to the N pole yoke claw 31A is defined as a reference position S0. At the neutral point, the claw 41B of the second intermediate yoke is located at the reference position S0. At this time, the claw 41A of the first intermediate yoke is disposed at a position on the clockwise side of the paper with respect to the claw 31A of the N pole yoke, in an intermediate position between the claw 31A of the N pole yoke and the claw 31B of the S pole yoke. The Accordingly, the N pole yoke pawl 31A, the first intermediate yoke pawl 41A, the S pole yoke pawl 31B, and the second intermediate yoke pawl 41B are arranged in this order in the circumferential direction.

  At this neutral point, the claw 41A of the first intermediate yoke and the claw 41A of the second intermediate yoke are disposed at an intermediate position between the claw 31A of the N pole yoke and the claw 31B of the S pole yoke. None of the nails overlap. At this time, the magnetic flux directed from the N pole yoke claw 31A to the first intermediate yoke claw 41A and the magnetic flux directed from the N pole yoke claw 31A to the second intermediate yoke claw 41B are substantially canceled. Similarly, the magnetic flux from the first intermediate yoke claw 41A to the south pole yoke claw 31B and the magnetic flux from the second intermediate yoke claw 41B to the south pole yoke claw 31B are substantially canceled. That is, magnetic flux due to “overlap between claws” as described in FIGS. 5 and 6 does not occur.

  However, there is fundamentally a magnetic flux from the N pole to the S pole of the magnet 2Z. That is, the magnetic flux (hereinafter referred to as the magnetic flux) transmitted from the N pole of the magnet 2Z to the first intermediate yoke 4A via the N pole yoke 3A and from the second intermediate yoke 4B to the S pole of the magnet 2Z via the S pole yoke 3B. (Referred to as “base magnetic flux”) (see FIG. 4B). The magnetic flux density Φ0 of the base magnetic flux is detected by the magnetic sensor 6.

When a steering torque is applied between the input shaft 11 and the output shaft 12 with respect to the neutral point and a torsional displacement occurs in the torsion bar 13, the magnet 2Z and the N / S pole yokes 3A and 3B fixed to the input shaft 11 are generated. Then, the intermediate yokes 4A and 4B fixed to the output shaft 12 rotate relative to each other.
In the state shown in FIG. 5, the position S + of the claw 41B of the second intermediate yoke is rotated counterclockwise by an angle θ + with respect to the reference position S0. Hereinafter, this rotation direction is referred to as “advance direction”. At this time, in the axial projection, the claw 31A of the N pole yoke and the claw 41A of the first intermediate yoke overlap, and the claw 31B of the S pole yoke and the claw 41B of the second intermediate yoke overlap. Then, the magnetic field lines having N polarity increase in the first intermediate yoke 4A, and the magnetic field lines having S polarity increase in the second intermediate yoke 4B. As a result, the magnetic sensor 6 is moved downward from above in FIG. A positive magnetic flux density Φ1 is generated.

  In the state shown in FIG. 6, the position S− of the claw 41B of the second intermediate yoke is rotated clockwise by an angle θ− with respect to the reference position S0. Hereinafter, this rotation direction is referred to as “return direction”. At this time, in the axial projection, the N pole yoke claw 31A and the second intermediate yoke claw 41B overlap, and the S pole yoke claw 31B and the first intermediate yoke claw 41A overlap. Then, the magnetic field lines having N polarity increase in the second intermediate yoke 4B, and the magnetic field lines having S polarity increase in the first intermediate yoke 4A. As a result, the magnetic sensor 6 moves upward from below in FIG. 6B. A negative magnetic flux density Φ2 is generated.

  FIG. 8A is a characteristic diagram showing the “relationship between the rotation angle (twisting displacement) θ and the detected magnetic flux density Φ of the magnetic sensor 6” in the first embodiment. As indicated by a broken line B1 in FIG. 8A, the detected magnetic flux density Φ changes in the positive and negative directions around the magnetic flux density Φ0 of the base magnetic flux according to the rotation angle θ from the neutral point. In the present embodiment, since the nail arrangement period is 45 °, the detected magnetic flux density Φ changes from the minimum value to the maximum value in the range of the rotation angle θ of ± 11.25 ° theoretically.

  As described above, the magnetic flux density passing through the magnetic sensor 6 is approximately proportional to the amount of torsional displacement of the torsion bar 13 and the polarity is inverted according to the torsional direction of the torsion bar 13. The magnetic sensor 6 detects the magnetic flux density and outputs it as a voltage signal, so that the torque sensor 3 can detect the steering torque between the input shaft 11 and the output shaft 12.

  Then, the effect of the torque sensor 3 of this embodiment is demonstrated. When the intermediate yokes 4A and 4B rotate relative to the N / S pole yokes 3A and 3B from the neutral point, the torque sensor 3 includes the intermediate yoke claws 41A and 41B and the N / S pole yoke claws 31A and 31B. Overlapping in axial projection. Thereby, the opposing area of the yokes constituting the magnetic flux transmission path can be effectively ensured without increasing the size of the torque sensor 3.

  The magnetic flux collecting yokes 5A and 5B are opposed to the intermediate yokes 4A and 4B in the axial direction, and collect magnetic flux from the intermediate yokes 4A and 4B. The magnetic sensor 6 is provided between the magnetic flux collecting yokes 5A and 5B, and detects the magnetic flux density of the magnetic flux collected by the magnetic flux collecting yokes 5A and 5B. Thereby, the magnetic flux of a magnetic circuit can be detected efficiently.

The following second to sixth embodiments are the same as the first embodiment, and the configuration of the detection unit is different. In addition, the same code | symbol is attached | subjected to the structure substantially the same as the structure which concerns on 1st Embodiment, and description is abbreviate | omitted.
(Second Embodiment)
The detection unit 202 according to the second embodiment of the present invention will be described with reference to FIG.
FIG. 7 is a diagram of a neutral point where the torsional displacement of the torsion bar 13 is zero in the detection unit 202. As shown in FIG. 7, in the detection unit 202, the claw 41A of the first intermediate yoke and the claw 41B of the second intermediate yoke are at a neutral point between the claw 31A of the N pole yoke 3A and the claw 31B of the S pole yoke 3B. They are displaced in the clockwise direction of FIG. 7 with respect to the intermediate position. More specifically, the claw 41B of the second intermediate yoke is disposed in the return direction by an angle α with respect to the reference position S0. Therefore, in the detection part 201 of 1st Embodiment, it will be in the state similar to the state (FIG. 6) which intermediate yoke 4A, 4B rotated relatively in the "return direction" with respect to N / S pole yoke 3A, 3B.

Here, the significance of the second embodiment will be described with reference to FIG.
As shown by the broken line B1 in FIG. 8A, in the detection unit 201 of the first embodiment, as described above, the magnetic flux density Φ0 of the base magnetic flux is generated at the neutral point, and according to the rotation angle θ from the neutral point, The detected magnetic flux density Φ changes in the positive and negative directions around the magnetic flux density Φ0 of the base magnetic flux. That is, the magnetic flux density Φ changes based on the offset magnetic flux density Φ0, not on the basis of zero. In this case, there is a possibility that the linear region R1 having the magnetic flux density Φ cannot be obtained sufficiently.

On the other hand, in the second embodiment, the intermediate yokes 4A and 4B are biased in the “return direction” with respect to the N / S pole yokes 3A and 3B at the neutral point. And the magnetic flux density Φ detected by the magnetic sensor 6 at the neutral point can be made zero as shown by a solid line B2 in FIG.
Thereby, since the magnetic flux density detected according to the torsional displacement of the torsion bar 13 changes centering on zero, the linear region R2 of magnetic flux density can be extended.

(Third embodiment)
Next, the detection part 203 of 3rd Embodiment of this invention is demonstrated with reference to FIG.
The detection unit 203 includes the annular magnet 2Z, the N-pole yoke 3A, and the S-pole yoke 3B in the circumferential direction in the detection unit 202 of the second embodiment (see FIG. 7 and FIG. 3 that uses the first embodiment). It is divided into four parts.
FIG. 9 shows an N-pole yoke 3AQ formed by dividing it into four in the circumferential direction. On the lower side (the other side of the drawing) of the N pole yoke 3AQ, a magnet and an S pole yoke, which are similarly divided into four in the circumferential direction, are provided, and constitute four division units together with the N pole yoke 3AQ.

  By forming the magnet and the N / S pole yoke in the circumferential direction, for example, by dividing into 4 to 8 parts, it becomes easy to manufacture parts. In addition, compared with the case where the torsion bar 13 is inserted through the annular magnet and the N / S pole yoke, the divided magnet and the N / S pole yoke can be attached from the radially outward direction of the torsion bar 13, so that the assembling property is improved. To do.

(Fourth embodiment)
Next, the detection part 204 of 4th Embodiment of this invention is demonstrated with reference to FIGS. The upper direction in FIG. 10 will be described as “up” and the lower direction in FIG. 10 will be described as “down”.
The fourth embodiment is different from the first embodiment in the magnetizing direction of the magnet, the arrangement direction of the “one set of magnet end yokes”, and the claws of the “one set of magnet end yokes” and the “one set of intermediate yokes”. This is an embodiment in which the facing direction is changed from “axial direction” to “radial direction”. The fourth embodiment is different from the first embodiment only in these directions, and the basic technical idea is common.

The detection unit 204 includes a magnet 2R, an outer pole yoke 3C and an inner pole yoke 3D (hereinafter collectively referred to as “outer / inner pole yokes 3C and 3D”), “one set of magnet end yokes”, and “one. The first intermediate yoke 4C and the second intermediate yoke 4D as “a set of intermediate yokes”, the first magnetic collection yoke 5C and the second magnetic collection yoke 5D as “a set of magnetic collection yokes”, and the magnetic sensor 6. The
The magnet 2 </ b> R is a monopolar magnet that is fixed to the input shaft 11 and magnetized in the “radial direction” on the N pole and the S pole. In the present embodiment, the radially outer side is magnetized to the N pole, and the inner side is magnetized to the S pole (see FIGS. 10 and 11).

The outer pole yoke 3C is connected to the outside of the N pole of the magnet 2R, and the inner pole yoke 3D is connected to the inside of the S pole of the magnet 2R.
The outer / inner pole yokes 3C, 3D have a plurality of claws 31C, 31D protruding from the ring portions 30C, 30D to one side in the axial direction (lower side in the present embodiment) at equal intervals in the circumferential direction. . Further, the outer pole yoke claw 31C and the inner pole yoke claw 31D are alternately arranged in the circumferential direction. In this embodiment, the outer pole yoke 3C and the inner pole yoke 3D have eight claws 31C and 31D at 45 ° intervals, respectively. The outer pole yoke claw 31C and the inner pole yoke claw 31D are: They are alternately arranged with a shift of 22.5 ° from each other (see FIG. 12).

The first intermediate yoke 4C and the second intermediate yoke 4D are fixed to the output shaft 12 on the lower side in the axial direction of the outer / inner pole yokes 3C and 3D, that is, on the side where the plurality of claws 31C and 31D protrude, and are separated from each other. ing. The intermediate yokes 4C and 4D form a magnetic circuit together with the magnet 2R and the outer / inner pole yokes 3C and 3D. When the relative position between the outer / inner pole yokes 3C and 3D changes according to the twist of the torsion bar 13, the magnetic flux density generated in the magnetic circuit changes.
The intermediate yokes 4C and 4D have a plurality of claws 41C and 41D that protrude in the axial direction (upward in this embodiment) from the ring portions 40C and 40D toward the magnet 2R at equal intervals in the circumferential direction. Further, the claws 41C of the first intermediate yoke and the claws 41D of the second intermediate yoke are alternately arranged in the circumferential direction.

  In the present embodiment, the ring portion 40C of the first intermediate yoke has a larger diameter than the ring portion 40D of the second intermediate yoke. Further, the ring portion 40C of the first intermediate yoke is disposed above the axial direction, and the ring portion 40D of the second intermediate yoke is disposed below the axial direction. The claw 41C of the first intermediate yoke and the claw 41D of the second intermediate yoke have eight claws 41C and 41D at intervals of about 45 °, respectively.

  The claw 41C of the first intermediate yoke extends from the ring portion 40C in the radially inward direction, and then bends upward in the axial direction at a position substantially the same diameter as the ring portion 40D of the second intermediate yoke. The claw 41D of the second intermediate yoke extends straight upward from the ring portion 40D. Further, the claws 41C of the first intermediate yoke and the claws 41D of the second intermediate yoke are alternately arranged with a shift of 22.5 ° from each other.

The first magnetic flux collecting yoke 5C is provided on the radially outer side of the first intermediate yoke 4C along a part in the circumferential direction of the ring portion 40C of the first intermediate yoke 4C (about 120 ° in the present embodiment). The second magnetism collecting yoke 5D is provided on the radially outer side of the second intermediate yoke 4D along a part in the circumferential direction of the ring portion 40D of the second intermediate yoke 4D. The magnetic collecting yokes 5C and 5D are opposed to the intermediate yokes 4C and 4D in the radial direction, and collect magnetic flux from the intermediate yokes 4C and 4D.
The magnetic sensor 6 is provided between the first magnetism collecting yoke 5C and the second magnetism collecting yoke 5D, detects the magnetic flux density collected by the magnetism collecting yokes 5C, 5D, converts it into a voltage signal, and outputs it. Specifically, a Hall element, a magnetoresistive element, or the like can be used as the magnetic sensor 6.

  Next, the operation of the detection unit 204 will be described with reference to FIG. 11B, FIG. 12, and FIG. 12 is an XII-XII cross-sectional schematic diagram at the neutral point of FIG. 11B, and FIGS. 13A and 13B are cross-sectional schematic diagrams corresponding to FIG. 12 when torsional displacement occurs. is there.

FIG. 11B exaggerates the axial direction (vertical direction in the figure). The magnet 2R and the outer / inner pole yokes 3C, 3D are fixed to the input shaft 11 side of the torsion bar 13, and the intermediate yokes 4C, 4D are fixed to the output shaft 12 side of the torsion bar 13.
12 and 13, the rotational position of the input shaft 11 side, that is, the magnet 2R and the outer / inner pole yokes 3C, 3D is fixed, and the output shaft 12 side, that is, the intermediate yokes 4C, 4D is fixed to the magnet 2R and the outer / inner poles. The state rotated relative to the yokes 3C and 3D is shown. 12 and 13 show only the relative rotational positions of the claws 31C and 31D of the outer / inner pole yoke and the claws 41C and 41D of the intermediate yoke.

  First, FIG. 12 shows a neutral point state in which no steering torque is applied between the input shaft 11 and the output shaft 12 and no torsional displacement occurs in the torsion bar 13. Here, among the intermediate positions between the outer pole yoke claw 31D and the inner pole yoke claw 31D, the position on the counterclockwise side of the drawing with respect to the outer pole yoke claw 31C is defined as a reference position S0. At the neutral point, the claw 41D of the second intermediate yoke is located at the reference position S0. At this time, the claw 41C of the first intermediate yoke is disposed at a position on the clockwise side of the paper with respect to the claw 31C of the outer pole yoke, in an intermediate position between the claw 31C of the outer pole yoke and the claw 31D of the inner pole yoke. The Therefore, the outer pole yoke claw 31C, the first intermediate yoke claw 41C, the inner pole yoke claw 31D, and the second intermediate yoke claw 41D are arranged in this order in the circumferential direction.

At this time, none of the claws overlap in the radial projection. Therefore, magnetic flux due to “overlap between claws” as described in FIG. 13 does not occur.
However, as described in the first embodiment, a base magnetic flux is generated.

When a steering torque is applied between the input shaft 11 and the output shaft 12 with respect to the neutral point and a torsional displacement is generated in the torsion bar 13, the magnet 2Z and the outer / inner pole yokes 3C, 3D fixed to the input shaft 11 are generated. And the intermediate yokes 4C and 4D fixed to the output shaft 12 rotate relative to each other.
In the state shown in FIG. 13A, the position S + of the claw 41D of the second intermediate yoke is rotated counterclockwise (advance direction) by an angle θ + with respect to the reference position S0. At this time, in the radial projection, the claw 31C of the outer pole yoke and the claw 41C of the first intermediate yoke overlap, and the claw 31D of the inner pole yoke and the claw 41D of the second intermediate yoke overlap. Then, a positive magnetic flux density is generated in the magnetic sensor 6 by the same action as the state shown in FIG. 5 of the first embodiment.

  In the state shown in FIG. 13B, the position S− of the claw 41D of the second intermediate yoke is rotated clockwise (return direction) by an angle θ− with respect to the reference position S0. At this time, in the radial projection, the claw 31C of the outer pole yoke and the claw 41D of the second intermediate yoke overlap, and the claw 31D of the inner pole yoke and the claw 41C of the first intermediate yoke overlap. Then, a negative magnetic flux density is generated in the magnetic sensor 6 by the same action as the state shown in FIG. 6 of the first embodiment.

As described above, the detection unit 204 of the fourth embodiment exhibits the characteristics of FIG. 8A by the same operation as the detection unit 201 of the first embodiment, and the input shaft 11 and the output shaft are detected by the detected magnetic flux density Φ. 12 can be detected.
In the fourth embodiment, when the intermediate yokes 4C, 4C rotate relative to the outer / inner pole yokes 3C, 3D from the neutral point, the intermediate yoke claws 41C, 41D and the outer / inner pole yoke claws 31C, 31D Overlap in radial projection. Thereby, similarly to 1st Embodiment, the opposing area of the yokes which comprise a magnetic flux transmission path | route can be ensured effectively, without enlarging the physique of a torque sensor.

  Further, the magnetic collecting yokes 5C and 5D are opposed to the intermediate yokes 4C and 4D in the radial direction, and collect magnetic flux from the intermediate yokes 4C and 4D. The magnetic sensor 6 is provided between the magnetic flux collecting yokes 5C and 5D, and detects the magnetic flux density of the magnetic flux collected by the magnetic flux collecting yokes 5C and 5D. Thereby, the magnetic flux of a magnetic circuit can be detected efficiently.

(Fifth and sixth embodiments)
Next, the detection units 205 and 206 of the fifth and sixth embodiments of the present invention will be described with reference to FIG.
The detection units 205 and 206 are each formed by dividing the annular magnet 2R and the outer / inner pole yokes 3C and 3D in the detection unit 204 (see FIG. 11) of the fourth embodiment into four in the circumferential direction.
In the detection unit 205 shown in FIG. 14A, the “magnet and one set of magnet end yokes” are configured by combining four division units each including a magnet 2RQ, an inner pole yoke 3CQ, and an outer pole yoke 3DQ. The gap between the adjacent divided units is relatively narrow.

In the detection unit 206 shown in FIG. 14B, the “magnet and one set of magnet end yokes” are configured by combining four divided units including the magnet 2RU, the inner pole yoke 3CU, and the outer pole yoke 3DU. The gaps between the adjacent divided units are relatively wide.
In this way, by forming the “magnet and a pair of magnet end yokes” in the circumferential direction, parts can be manufactured easily and the assembly can be improved as in the detection unit 203 of the third embodiment. To do.

(Other embodiments)
(A) The number of claws of the “one set of magnet end yokes” and the number of claws of the “one set of intermediate yokes” are not limited to eight illustrated in the above embodiment. Moreover, the shape of each nail | claw is not restricted to the shape of the said embodiment.
(A) The N pole and the S pole may be magnetized in the axial direction opposite to the first to third embodiments, that is, the lower side is the N pole and the upper side is the S pole. Further, with respect to the fourth to sixth embodiments, the N pole and the S pole may be magnetized in opposite directions in the radial direction, that is, the inner diameter is the N pole and the outer diameter is the S pole. Correspondingly, the polarity of the “one set of magnet end yokes” at each relative rotational position is also opposite to that in the above embodiment.

(C) It is not necessary to provide “a set of magnetism collecting yokes”.
(D) In the above embodiment, “a magnet and a set of magnet end yokes” are fixed to the input shaft 11 side of the torsion bar 13, and “a set of intermediate yokes” are fixed to the output shaft 12 of the torsion bar 13. . Conversely, the “magnet and the set of magnet end yokes” may be fixed to the output shaft 12, and the “set of intermediate yokes” may be fixed to the input shaft 11.

(E) The torque sensor of the present invention can be applied not only to an electric power steering device but also to various devices that detect shaft torque.
As mentioned above, this invention is not limited to such embodiment, In the range which does not deviate from the meaning of invention, it can implement with a various form.

3 ... torque sensor,
11: Input shaft (first shaft),
12 ... Output shaft (second shaft),
13 ・ ・ ・ Torsion bar,
2Z, 2R ... magnets,
201, 202, 203, 204, 205, 206 ... detection unit,
3A ... N pole yoke (magnet end yoke),
3B S pole yoke (magnet end yoke),
3C ... outer pole yoke (magnet end yoke),
3D ... Inner pole yoke (magnet end yoke),
30A, 30B, 30C, 30D ... Ring part,
31A, 31B, 31C, 31D ... nail,
4A ... 1st intermediate yoke (intermediate yoke),
4B ... 2nd intermediate yoke (intermediate yoke),
4C ... 1st intermediate yoke (intermediate yoke),
4D ... 2nd intermediate yoke (intermediate yoke),
40A, 40B, 40C, 40D ... ring part,
41A, 41B, 41C, 41D ... nails,
5A ... 1st magnetism collection yoke (magnetism collection yoke),
5B ... 2nd magnetism collection yoke (magnetism collection yoke),
5C ... 1st magnetism collection yoke (magnetism collection yoke),
5D ... 2nd magnetism collection yoke (magnetism collection yoke),
6 ... Magnetic sensor.

Claims (8)

A torsion bar that connects the first shaft and the second shaft coaxially and converts torque applied between the first shaft and the second shaft into a torsional displacement;
A magnet fixed to one end side of the first shaft or the torsion bar, and magnetized in the N-pole and S-pole in the axial direction;
A pair of magnet end yokes comprising an N pole yoke connected to the N pole of the magnet and an S pole yoke connected to the S pole of the magnet, wherein the N pole yoke and the S pole yoke are out of diameter. A pair of magnet end yokes having a plurality of claws protruding in the circumferential direction at equal intervals in the circumferential direction, wherein the claws of the N pole yoke and the claws of the S pole yoke are alternately arranged shifted in the circumferential direction;
The set of magnet end yokes includes a first intermediate yoke and a second intermediate yoke that are fixed to the second shaft or the other end side of the torsion bar outside the diameter of the set of magnet end yokes and are spaced apart from each other. And a pair of intermediate yokes that change the magnetic flux density generated in the magnetic circuit when rotated relative to the pair of magnet end yokes according to the torsion of the torsion bar.
A magnetic sensor for detecting a magnetic flux density generated in the magnetic circuit;
With
The set of intermediate yokes, when rotated relative to the set of magnet end yokes, at least partly overlaps with the claws of the set of magnet end yokes in an axial projection. Sensor. The first intermediate yoke and the second intermediate yoke have a plurality of claws protruding radially inward at equal intervals in the circumferential direction, and the claws of the first intermediate yoke and the claws of the second intermediate yoke are circumferential. Alternately arranged in the direction,
When the relative rotation position between the set of magnet end yokes and the set of intermediate yokes is a predetermined position, one of the claws of the N pole yoke or the S pole yoke, the claws of the first intermediate yoke, The other claw of the N pole yoke or the S pole yoke and the claw of the second intermediate yoke are alternately arranged in this order in the circumferential direction,
When the set of intermediate yokes rotate relative to the set of magnet end yokes from the predetermined position, the claws of the set of magnet end yokes and the claws of the set of intermediate yokes project in the axial direction. The torque sensor according to claim 1, wherein the torque sensors overlap with each other.   At the neutral point, the claw of the first intermediate yoke and the claw of the second intermediate yoke are at the neutral point so that the magnetic flux generated in the magnetic circuit is zero at the neutral point where the torsional displacement of the torsion bar is zero. The torque sensor according to claim 2, wherein the torque sensor is arranged so as to be shifted with respect to an intermediate position between a claw of the N pole yoke and a claw of the S pole yoke. A torsion bar that connects the first shaft and the second shaft coaxially and converts torque applied between the first shaft and the second shaft into a torsional displacement;
A magnet fixed to one end of the first shaft or the torsion bar and magnetized in the radial direction to the N pole and the S pole;
A pair of magnet end yokes comprising an outer pole yoke connected to a magnetic pole outside the diameter of the magnet and an inner pole yoke connected to a magnetic pole inside the diameter of the magnet, the outer pole yoke and the inner pole The yoke has a plurality of claws protruding on one side in the axial direction at equal intervals in the circumferential direction, and the claws of the outer pole yoke and the claws of the inner pole yoke are alternately arranged in the circumferential direction. A pair of magnet end yokes;
A pair of first and second intermediate yokes fixed to the other end of the second shaft or the torsion bar on the side from which the claws of the pair of magnet end yokes protrude in the axial direction, A set of intermediate yokes that form a magnetic circuit together with a set of magnet end yokes, and in which the magnetic flux density generated in the magnetic circuit changes when rotated relative to the set of magnet end yokes according to torsion of the torsion bar When,
A magnetic sensor for detecting a magnetic flux density generated in the magnetic circuit;
With
The set of intermediate yokes, when rotated relative to the set of magnet end yokes, at least a portion thereof overlaps with the claws of the set of magnet end yokes in a radial projection. Sensor. The first intermediate yoke and the second intermediate yoke have a plurality of claws protruding in the axial direction toward the magnet at equal intervals in the circumferential direction, and the claws of the first intermediate yoke and the second intermediate yoke The nail is alternately arranged in the circumferential direction,
When the position of relative rotation between the set of magnet end yokes and the set of intermediate yokes is a predetermined position, one of the claws of the outer pole yoke or the inner pole yoke, the claws of the first intermediate yoke, The other claw of the outer pole yoke or the inner pole yoke and the claw of the second intermediate yoke are alternately arranged in this order in the circumferential direction,
When the pair of intermediate yokes rotate relative to the set of magnet end yokes from the predetermined position, the claws of the pair of magnet end yokes and the claws of the pair of intermediate yokes project in the radial direction. The torque sensor according to claim 4, wherein the torque sensor overlaps with each other.   At the neutral point, the claw of the first intermediate yoke and the claw of the second intermediate yoke are at the neutral point so that the magnetic flux generated in the magnetic circuit is zero at the neutral point where the torsional displacement of the torsion bar is zero. The torque sensor according to claim 5, wherein the torque sensor is arranged so as to be shifted with respect to an intermediate position between a claw of the outer pole yoke and a claw of the inner pole yoke.   The torque sensor according to any one of claims 1 to 6, wherein the magnet and the magnet end yoke are formed by being divided in a circumferential direction. A set of magnetism collecting yokes that face the set of intermediate yokes in the axial direction or the radial direction and collect magnetic flux from the set of intermediate yokes,
The magnetic sensor is provided between the set of magnetic flux collecting yokes and detects a magnetic flux density of magnetic flux collected by the set of magnetic flux collecting yokes. The torque sensor according to item.

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