JP2012237727A - Torque sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a torque sensor that reduces an influence of periodic changes in magnetic fluxes associated with torsional displacement and stabilizes outputs of a magnetic sensor.SOLUTION: A torque sensor 2 is constituted by: a torsion bar 13 for coaxially connecting an input axis 11 and an output axis 12; a multipolar magnet 14 fixed to the input axis 11; a pair of magnetic yokes 31, 32 fixed to the output axis 12; a pair of magnetism collecting rings 611, 612 for collecting magnetic fluxes from the magnetic yokes 31, 32; and a magnetic sensor 41 for detecting a magnetic flux density. The pair of the magnetism collecting rings 611, 612 are formed in elliptical shapes and have maximum distances to the multipolar magnet 14 at a magnetism collecting part 61a provided with the magnetic sensor 41. Namely, the magnetic sensor 41 is arranged to be distanced from the multipolar magnet 14 as much as possible. As a result, the influence of periodic changes in magnetic fluxes on the magnetic sensor 41 is reduced. Thus, output voltages of the magnetic sensor 41 can be stabilized.

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, in the torque sensor described in Patent Document 1, when the torsion bar connecting the input shaft and the output shaft is twisted, the torque sensor is controlled by the change in the relative position in the circumferential direction between the multipolar magnet and the pair of magnetic yokes. The shaft torque is detected by detecting the magnetic flux generated in the pair of magnetic yokes.
Further, in the second embodiment of Patent Document 2, a set of magnetic flux collecting rings that collect magnetic flux from a set of magnetic yokes is semicircular so that it can be assembled from the radial direction to improve the assemblability. Yes.
In addition, the torque sensor of Patent Document 3 uses a magnet that is magnetized with one pole in the axial direction as an N pole and the other as an S pole.

JP 2003-149062 A JP 2003-329523 A JP 2008-216019 A

  In the torque sensors disclosed in Patent Documents 1 and 2, a set of magnetism collecting rings as “a set of magnetism collectors” is arranged in the radially outward direction of the set of magnetic yokes, and faces the set of magnetic yokes only in the radial direction. doing. Therefore, if a set of magnetism collecting rings is disposed between the axial directions of a set of magnetic yokes, the set of magnetism collecting rings and the set of magnetic yokes are opposed to each other in the axial direction to generate a magnetic flux that can be collected. Can be increased.

  However, in that case, if the magnetic sensor that detects the magnetic flux density collected by a pair of magnetic flux collecting rings is brought too close to the inner multipolar magnet, it will be more susceptible to the periodic fluctuation of the magnetic flux due to torsional displacement. . Therefore, there arises a problem that the output voltage of the magnetic sensor periodically fluctuates when the torsion bar rotates in a constant torque state.

  In addition, the torque sensor of Patent Document 3 is provided with three sets of three members, a magnet-side magnetic body, a magnetic body, and an auxiliary magnetic body, as members that transmit magnetic flux in the radially outward direction of the magnet (FIG. 1). To FIG. 3). That is, the two members of the magnet-side magnetic body and the magnetic body correspond to “a set of magnetic yokes”, and the auxiliary magnetic body corresponds to “a set of magnetic current collectors”. As described above, the torque sensor of Patent Document 3 has problems such as a large number of parts, a large size in the radial direction, and a complicated shape of each component.

  The present invention has been created in view of the above points, and an object of the present invention is to provide a torque sensor having a simple configuration that suppresses the influence of periodic fluctuations of magnetic flux accompanying torsional displacement and stabilizes the output of the magnetic sensor. It is to provide.

A torque sensor according to a first aspect includes a torsion bar, a multipolar magnet, a set of magnetic yokes, a set of magnetic current collectors, 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.
The multipolar magnet is fixed to one end of the first shaft or torsion bar.
The pair of magnetic yokes are fixed to the second shaft or the other end of the torsion bar outside the diameter of the multipole magnet, and are opposed to each other via a gap in the axial direction so that a magnetic field is generated in the magnetic field generated by the multipole magnet. Form a circuit.
The set of magnetic current collectors is provided between the axial directions of the set of magnetic yokes so that at least a portion thereof overlaps with the set of magnetic yokes in the axial projection. The set of magnetic current collectors collects magnetic flux from the set of magnetic yokes.
The magnetic sensor detects the strength of the magnetic field between a pair of magnetic current collectors.
In the set of magnetic current collectors, the distance from the central axis of the multipolar magnet to the inner edge is maximum in the X direction connecting the central axis of the multipolar magnet and the magnetic sensor.

  In each set of magnetic yokes, the same number of claws extending in the axial direction as the N poles and S poles of the multipolar magnet are provided at equal intervals along the inner edge of the ring. Then, the claws of one magnetic yoke and the claws of the other magnetic yoke are alternately arranged in the circumferential direction. Therefore, the cross-sectional shape of the magnetic yoke in the axial direction is “L-shaped” in the portion with the claw and “one-shaped” in the portion without the claw, and the “L-shaped” section and the “one-shaped” section are divided. Appears alternately in the circumferential direction.

  With this configuration, the pair of magnetic current collectors is inserted between the pair of magnetic yokes in the axial direction, and at least a part thereof overlaps with the pair of magnetic yokes in the axial projection. Thereby, a set of magnetic current collectors can collect magnetic flux which has not been conventionally used as leakage magnetic flux. Therefore, the amount of magnetic flux that can be collected is the same or more.

In addition, the pair of magnetic current collectors has a maximum distance from the multipolar magnet at a portion where the magnetic sensor is disposed. That is, the magnetic sensor is arranged as far as possible from the multipolar magnet. Thereby, the influence on the magnetic sensor due to the periodic fluctuation of the magnetic flux is reduced. Therefore, the output voltage of the magnetic sensor can be stabilized.
Furthermore, since the members that transmit the magnetic flux of the multipolar magnet are two sets of “one set of magnetic yokes” and “one set of magnetic current collectors”, the number of parts is small compared to the prior art of Patent Document 3, The dimension in the radial direction is small, and the shape of each component is simple. Therefore, the configuration is simplified.

According to the second aspect of the present invention, in the pair of magnetic current collectors, the distance from the central axis to the inner edge of the multipolar magnet is minimum in the Y direction orthogonal to the X direction.
The further away from the magnetic sensor, the less likely to be affected by fluctuations in magnetic flux even when the distance between the pair of magnetic collectors and the multipolar magnet is short. Therefore, specifically, the set of current collectors is set so that the distance between the current collector and the multipolar magnet is minimized in the Y direction orthogonal to the X direction, that is, the direction rotated ± 90 ° with respect to the X direction. The shape of the magnetic body can be set.

Furthermore, according to the invention described in claim 3, in the pair of magnetic current collectors, the distance from the central axis to the inner edge of the multipolar magnet increases continuously as it goes from the Y direction to the X direction.
Specifically, this configuration can be realized by setting the shape of the pair of magnetic current collectors to be “an elliptical shape having a major axis in the X direction and a minor axis in the Y direction”.

According to the fourth aspect of the present invention, the set of magnetic current collectors has a notch portion in which the distance from the central axis of the multipolar magnet to the inner edge portion increases discontinuously from other regions in the region including the X direction. It is formed.
Thus, a notch may be provided in a region including the X direction, and the magnetic sensor may be kept away from the multipolar magnet. This makes it easy to keep the magnetic sensor far away from the multipolar magnet, particularly when there is a large problem due to magnetic flux fluctuations.

According to the invention described in claim 5, the set of magnetic current collectors has an opening in a direction perpendicular to the axial direction, and the axial direction of the set of magnetic yokes from one radial side of the set of magnetic yokes. Inserted between.
With this configuration, the set of magnetic current collectors is inserted between the radial direction of the set of magnetic yokes and the axial direction of the set of magnetic yokes, so that the assembling property can be improved. For example, in the invention according to claim 5 that depends on claim 3, the shape of the pair of magnetic current collectors is “a semi-elliptical shape only on the magnetic sensor side in the X direction with the major axis in the X direction and the minor axis in the Y direction”. can do.
In this way, when the set of current collectors is semi-annular, the number of members of the set of current collectors is reduced compared to the case of an annular shape, so the magnetic flux smoothing effect is reduced and the effects of magnetic flux fluctuations are more growing. However, in the present invention, since the magnetic sensor is arranged as far as possible from the multipolar magnet, the influence on the magnetic sensor due to the periodic fluctuation of the magnetic flux is reduced, and the output voltage of the magnetic sensor can be stabilized. it can.

According to the sixth aspect of the present invention, the set of magnetic current collectors has the magnetic flux collectors provided closer to each other in the axial direction than other portions of the magnetic current collector. The magnetic sensor is disposed between the magnetic flux collectors.
Thereby, the magnetic resistance of the site | part in which a magnetic sensor is provided can be minimized, and detection sensitivity can be improved.

According to the seventh aspect of the present invention, the set of magnetic yokes is integrally molded with a resin to form a cylindrical integrated yoke member, and at least a part of the set of magnetic current collectors is formed on the radially outer wall of the integrated yoke member. A groove to be inserted is formed.
By integrally resin-molding a set of magnetic yokes to form an integral yoke member, the magnetic yoke can be prevented from being displaced and the magnetic flux density can be stabilized. Moreover, a groove part is formed in the outer diameter wall of the integral yoke member, and an assemblability is improved by inserting a magnetic current collector into the groove part.

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) top view of the yoke unit by 1st Embodiment of this invention, (b) sectional drawing, (c) It is IIIc-IIIc sectional drawing of (a). 1A is a plan view of a sensor unit according to a first embodiment of the present invention, FIG. 2B is a cross-sectional view taken along the line IVb-IVb of FIG. 1A, and FIG. It is a principal part schematic diagram explaining the operating principle of the torque sensor by 1st Embodiment of this invention, (b): It is Vb-Vb sectional drawing of (a). It is a principal part schematic diagram explaining the operating principle of the torque sensor by 1st Embodiment of this invention, (b): It is VIb-VIb sectional drawing of (a). It is the top view and side view of the magnetism collection ring by 2nd, 3rd, 4th embodiment of this invention. It is the top view and side view of a magnetism collection ring by a 5th and 6th embodiment of the present invention. It is a side view of the magnetism collection part of the magnetism collection ring by other embodiment of this invention. It is a figure which shows arrangement | positioning of the magnetism collection ring by other embodiment of this invention. It is a top view of the magnetism collection ring by other embodiments of the present invention. It is a top view of the magnetism collection ring by other embodiments of the present invention. It is a top view of the magnetism collection ring by other embodiments of the present invention. It is a disassembled perspective view of the torque sensor of a comparative example. It is the (A) principal part schematic diagram of the torque sensor of a comparative example, (b) It is XVb-XVb sectional drawing of (a).

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 2 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. 1 shows the overall configuration of a steering system provided with an electric power steering device 5. A torque sensor 2 for detecting a steering torque is installed on a steering shaft 92 connected to the handle 91. 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 pair of wheels 98 are steered.

  The torque sensor 2 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 it to the ECU 6. The ECU 6 controls the output of the electric motor 7 according to the detected steering torque. The steering assist torque generated by the electric motor 7 is decelerated via the reduction gear 95 and transmitted to the steering shaft 92.

Next, the configuration of the torque sensor 2 will be described with reference to FIG. 1, FIG. 3, and FIG.
As shown in FIG. 1, the torque sensor 2 includes a torsion bar 13, a multipolar magnet 14, a set of magnetic yokes 31 and 32, a set of magnetism collecting rings 611 and 612 as “a set of magnetism collectors”, and It consists of a magnetic sensor 41 and the like.
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 cylindrical multipolar magnet 14 is fixed to the input shaft 11 and N and S poles are alternately magnetized in the circumferential direction. For example, in this embodiment, the number of N poles and S poles is 12 pairs, for a total of 24 poles (see FIGS. 5 and 6). In other embodiments, the number of magnetic poles of the multipolar magnet is not limited to 24 but may be an even number.
The pair of magnetic yokes 31 and 32 is an annular body made of a soft magnetic material, and is fixed to the output shaft 12 outside the diameter of the multipolar magnet 14. In the magnetic yokes 31 and 32, the same number (12 in this embodiment) of claws 31 a and 32 a as the N poles and S poles of the multipolar magnet 14 are provided at equal intervals along the inner edge of the ring. The claws 31a of one magnetic yoke 31 and the claws 32a of the other magnetic yoke 32 are alternately arranged with a shift in the circumferential direction. Thus, one magnetic yoke 31 and the other magnetic yoke 32 are opposed to each other via the air gap in the axial direction (see FIG. 3). The pair of magnetic yokes 31 and 32 form a magnetic circuit in the magnetic field generated by the multipolar magnet 14.

  Here, the multipolar magnet 14 and the pair of magnetic yokes 31 and 32 are not subjected to twisting displacement in the torsion bar 13, that is, no steering torque is applied between the input shaft 11 and the output shaft 12. At this time, the centers of the claws 31a and 32a of the magnetic yokes 31 and 32 are arranged so that the boundary between the N pole and the S pole of the multipolar magnet 14 coincides.

In the present embodiment, as shown in FIG. 3, the pair of magnetic yokes 31 and 32 are integrally molded with a mold resin 33 to constitute a yoke unit 30 as an “integrated yoke member”.
The yoke unit 30 has a bobbin shape in which a groove 34 is formed on the outer diameter wall and a shaft hole 35 is formed on the inner diameter side. The groove portion 34 is formed between the ring portion of one magnetic yoke 31 and the ring portion of the other magnetic yoke 32 in the axial direction. The bottom outer diameter φDg of the groove 34 is smaller than the outer diameter φDo of the yoke unit 30. Further, the inner diameter φDi of the shaft hole 35 is formed to be slightly larger than the outer diameter of the multipolar magnet 14.
As shown in FIG. 3C, the axial sectional shape of the pair of magnetic yokes 31 and 32 is “L-shaped” in the portion where the claws 31a and 32a are present, and “one” in the portion where the claws 31a and 32a are not present. “L-shaped” and “L-shaped” cross sections appear alternately in the circumferential direction.

  The pair of magnetism collecting rings 611 and 612 is formed of a soft magnetic material similar to the magnetic yokes 31 and 32 in a semi-elliptical shape, and is in the groove 34 of the yoke unit 30, that is, in the axial direction of the pair of magnetic yokes 31 and 32. It is arranged between. Therefore, at least a part of the pair of magnetism collecting rings 611 and 612 overlaps with the pair of magnetic yokes 31 and 32 in the axial projection. Thus, the pair of magnetism collecting rings 611 and 612 are opposed to the ring portions of the pair of magnetic yokes 31 and 32 in the axial direction.

  The pair of magnetic flux collecting rings 611 and 612 is formed with a concave magnetic flux collecting portion 61a at a substantially intermediate position in the circumferential direction of a semi-elliptical shape (see FIG. 4). The magnetism collecting portions 61a are provided closer to each other in the axial direction than other portions. The pair of magnetism collecting rings 611 and 612 collect magnetic flux from the pair of magnetic yokes 31 and 32 to the magnetism collecting part 61a.

The magnetic sensor 41 is provided between the two magnetic flux collectors 61a, detects the magnetic flux density generated between the magnetic flux collectors 61a, converts it to a voltage signal, and outputs it to the lead wire. Specifically, a Hall element, a magnetoresistive element, or the like can be used as the magnetic sensor 41.
In the present embodiment, as shown in FIG. 4, the pair of magnetism collecting rings 611 and 612 and the magnetic sensor 41 are integrally molded with a mold resin 43 to constitute a sensor unit 40. The magnetic sensor 41 is sandwiched between the two magnetism collecting portions 61a, and is integrated with the magnetism collecting portions 61a in contact with or as close as possible.

  In the sensor unit 40, the gap Wr between the openings of the pair of magnetism collecting rings 611 and 612 is set to be larger than the bottom outer diameter φDg of the groove 34 of the yoke unit 30. Further, the thickness Tr from the upper end surface of the magnetism collecting ring 611 to the lower end surface of the magnetism collecting ring 612 is set to be smaller than the height Hg of the groove portion 34. Therefore, the sensor unit 40 can be assembled by being inserted into the groove 34 from one radial side of the yoke unit 30.

As shown in FIG. 4C, the pair of magnetism collecting rings 611 and 612 has a distance from the central axis O of the yoke unit 30 to the inner edge 61f in the X direction connecting the central axis O and the magnetic sensor 41. It corresponds to the major axis r1 of the ellipse, and corresponds to the minor axis r2 of the ellipse in the Y direction orthogonal to the X direction. That is, the distance from the central axis O to the inner edge 61f is the maximum in the X direction and the minimum in the Y direction. And it increases continuously as it goes to the X direction from the Y direction.
Here, the central axis O of the yoke unit 30 coincides with the central axis O of the multipolar magnet 14 in the assembled state of the torque sensor 2 (see FIGS. 1, 5, and 6). It can be said that the distance from the central axis O of the multipolar magnet 14 to the inner edge 61f is the maximum in the X direction and the minimum in the Y direction.

  Next, the operation of the torque sensor 2 will be described with reference to FIGS. 5 shows a state in which the claw 32a of the magnetic yoke 32 faces the north pole of the multipolar magnet 14, and FIG. 6 shows a state in which the claw 32a of the magnetic yoke 32 faces the south pole of the multipole magnet 14. Indicates the state. 5A and 6A, only the claw 32a is indicated by a broken line, and the claw 31a is not shown.

First, in a neutral state in which no steering torque is applied between the input shaft 11 and the output shaft 12 and no torsional displacement is generated in the torsion bar 13, the state is intermediate between FIGS. That is, the center of the claw 32a of the magnetic yoke 32 coincides with the boundary between the N pole and the S pole of the multipolar magnet 14. At this time, the center of the claw 31a of the magnetic yoke 31 coincides with the boundary between the N pole and the S pole of the multipolar magnet 14.
In this state, the same number of magnetic lines of force enter and exit the claws 31a and 32a of the magnetic yokes 31 and 32 from the north and south poles of the multipolar magnet 14, so that the inside of one magnetic yoke 31 and the other magnetic yoke 32 is inside. Each magnetic field line forms a closed loop. Therefore, no magnetic flux leaks into the gap between the magnetic yoke 31 and the magnetic yoke 32, and the magnetic flux density detected by the magnetic sensor 41 is zero.

  When a steering torque is applied between the input shaft 11 and the output shaft 12 and the torsion bar 13 is twisted and displaced, a set of magnets fixed to the input shaft 11 and the output shaft 12 are fixed. The relative position with respect to the yokes 31 and 32 changes in the circumferential direction. As a result, as shown in FIG. 5 or FIG. 6, the centers of the claws 31a and 32a and the boundary between the N pole and the S pole of the multipolar magnet 14 are shifted in the circumferential direction. , The magnetic field lines having opposite polarities increase.

In the position shown in FIG. 5, the magnetic field lines having N polarity increase in the magnetic yoke 32 and the magnetic field lines having S polarity increase in the opposing magnetic yoke 31. As a result, the magnetic sensor 41 is moved from the lower side of FIG. A magnetic flux density Φ1 passing upward is generated.
At the position shown in FIG. 6, the magnetic field lines having S polarity increase in the magnetic yoke 32, and the magnetic field lines having N polarity increase in the opposing magnetic yoke 31. As a result, the magnetic sensor 41 is moved from above in FIG. A magnetic flux density Φ2 that passes downward is generated.

  Thus, the magnetic flux density passing through the magnetic sensor 41 is substantially proportional to the amount of twist displacement of the torsion bar 13 and the polarity is reversed according to the twist direction of the torsion bar 13. The magnetic sensor 41 detects this magnetic flux density and outputs it as a voltage signal, so that the torque sensor 2 can detect the steering torque between the input shaft 11 and the output shaft 12.

Here, as a comparative example, the prior art based on Patent Document 2 will be described with reference to FIGS. 14 and 15. Components substantially the same as those according to the first embodiment of the present invention are denoted by the same reference numerals and description thereof is omitted.
As shown in FIG. 14, the torque sensor 9 of the comparative example includes a pair of semi-annular magnetic flux collecting rings 91 and 92. Here, as shown in FIG. 15, a pair of magnetic yokes 31 and 32 are integrally resin-molded to form a yoke unit 39, and a pair of magnetic flux collecting rings 91 and 92 are integrated with the magnetic sensor 41. The sensor unit 49 is configured by being resin-molded in the same manner as in the first embodiment.
However, the pair of magnetism collecting rings 91 and 92 in the comparative example is semicircular, and the distance r from the central axis O to the inner edge portion 91f is equal in the X direction and the Y direction in the first embodiment. And different.

Then, the effect of the torque sensor 2 of this embodiment is demonstrated, contrasting with a comparative example.
(1) As in the comparative example, the torque sensor 2 of the present embodiment has a pair of magnetism collecting rings 611 and 612 formed in a semi-annular shape, and therefore the sensor unit 40 can be assembled from the radial direction of the yoke unit 30. it can. Therefore, the assembling property is improved.

  (2) In the comparative example, a set of semicircular magnetic flux collecting rings 91 and 92 are arranged in the radially outward direction of the set of magnetic yokes 31 and 32, and only in the radial direction with the set of magnetic yokes 31 and 32. Opposite. Therefore, compared with the case where the set of magnetism collecting rings is circular (shown by broken lines), the area facing the set of magnetic yokes 31 and 32 is reduced by about half, and the amount of magnetic flux that can be collected is reduced.

Therefore, in order to increase the magnetic flux that can be collected, a set of magnetism collecting rings is arranged between the pair of magnetic yokes 31 and 32 in the axial direction, and the set of magnetism collecting rings and the set of magnetic yokes 31 are arranged. , 32 are assumed to face each other in the axial direction. In that case, if the magnetic sensor 41 is brought too close to the radially inner multipolar magnet 14, the magnetic sensor 41 is easily affected by the periodic fluctuation of the magnetic flux accompanying torsional displacement. Therefore, there arises a problem that the output voltage of the magnetic sensor 41 periodically varies when the torsion bar 13 rotates in a constant torque state.
In particular, when a pair of magnetism collecting rings is semi-annular, the number of members of the magnetism collecting ring is reduced compared to the case of an annular shape, so the magnetic flux smoothing effect is reduced and the influence of magnetic flux fluctuations is greater. Become.

  On the other hand, in this embodiment, the pair of magnetism collecting rings 611 and 612 has the maximum distance from the central axis O of the multipolar magnet 14 to the inner edge 61f in the X direction connecting the central axis O and the magnetic sensor 41. It becomes. That is, the magnetic sensor 41 is arranged as far as possible from the multipolar magnet 14. Thereby, the influence on the magnetic flux sensor 41 by the periodic fluctuation | variation of magnetic flux is suppressed. Therefore, the output voltage of the magnetic flux sensor 41 can be stabilized.

In the present embodiment, the pair of magnetism collecting rings 611 and 612 further has a minimum distance from the central axis O of the multipolar magnet 14 to the inner edge 61f in the Y direction perpendicular to the X direction. It increases continuously from the direction toward the X direction.
The farther away from the magnetic flux collector 61a, that is, the farther away from the magnetic sensor 41, the less likely it is to be affected by fluctuations in magnetic flux even if the distance between the pair of magnetic flux collecting rings 611 and 612 and the multipolar magnet 14 is closer. Therefore, the shape of the pair of magnetic flux collecting rings 611 and 612 can be set so that the distance from the multipolar magnet 14 is minimized in the Y direction rotated by ± 90 ° with respect to the magnetic flux collecting portion 61a.

  (3) In the present embodiment, at least a part of the pair of magnetism collecting rings 611 and 612 overlaps with the pair of magnetic yokes 31 and 32 in the axial projection. As a result, the set of magnetism collecting rings 611 and 612 is opposed to the ring portion of the set of magnetic yokes 31 and 32 in the axial direction. The magnetic yokes 31 and 32 can be collected. Therefore, the amount of magnetic flux that can be collected can be increased.

  (4) The magnetism collecting portions 61a of the pair of magnetism collecting rings 611 and 612 are provided closer to the axial direction than other portions. Thereby, the magnetic resistance of the site | part in which the magnetic sensor 41 is provided can be minimized, and detection sensitivity can be improved. Furthermore, since the magnetic sensor 41 is in contact with or as close as possible to both the magnetic flux collectors 61a, the magnetic sensor 41 can detect the magnetic flux collected in the magnetic flux collector 61a as much as possible. The output of 41 is stabilized.

  (5) Since the pair of magnetic yokes 31 and 32 are integrally resin-molded to form the yoke unit 30, the magnetic yokes 31 and 32 can be prevented from being displaced and the magnetic flux density can be stabilized. Moreover, since the groove part 34 is formed in the diameter outer wall of the yoke unit 30, and the sensor unit 40 can be inserted and assembled | attached to the groove part 34, an assembly property improves.

  (6) Furthermore, in this embodiment, the members that transmit the magnetic flux of the multipolar magnet 14 are two sets of “one set of magnetic yokes 31 and 32” and “one set of magnetism collecting rings 611 and 612”. Compared with the prior art of Patent Document 3, the number of components is small, the radial dimension is small, and the shape of each component is simple. Therefore, the configuration is simplified.

Next, 2nd-6th embodiment of this invention is described with reference to FIG. 7, FIG. These embodiments differ from the first embodiment only in the shape of the magnetism collecting ring, and in the figure, the yoke unit 30 and the magnetic sensor 41 are substantially the same as the first embodiment.
Particularly in the second to fourth embodiments, the basic shape of the magnetism collecting ring is a semi-elliptical shape similar to that of the first embodiment. That is, the distance from the central axis O to the inner edge is maximum in the X direction connecting the central axis O and the magnetic sensor 41 and is minimum in the Y direction. And it increases continuously as it goes to the X direction from the Y direction.

(Second Embodiment)
As shown in FIGS. 7A, 7 </ b> B, and 7 </ b> C, the magnetic flux collecting rings 621 and 622 of the second embodiment are projections in which the magnetic flux collecting portion 62 a protrudes radially outward from a semi-elliptical ring body. It is formed into a shape. Further, the magnetic flux collecting portions 62a are bent so as to approach each other in the axial direction and to contact the magnetic sensor 41 or as close as possible.
Similarly to the first embodiment, the distance from the central axis O to the inner edge 62f is the maximum in the X direction and the minimum in the Y direction, and continuously increases from the Y direction toward the X direction.

(Third embodiment)
As shown in FIGS. 7D and 7E, the magnetism collecting rings 631 and 632 of the third embodiment have a distance from the central axis O to the inner edge 63f in the region including the X direction from other regions. A continuously increasing notch 63g is formed in an arc shape in the radial direction. Therefore, the distance between the central axis O and the inner edge portion 63f of the magnetic flux collecting portion 63a is further increased. Therefore, the magnetism collecting part 63a is not easily affected by the fluctuation of the magnetic field.

(Fourth embodiment)
As shown in FIGS. 7 (f) and 7 (g), the magnetism collecting rings 641 and 642 of the fourth embodiment have a distance from the central axis O to the inner edge 64f in the region including the X direction. A continuously increasing cutout portion 64g is formed in a V shape in the radial direction. Therefore, the distance from the central axis O to the inner edge portion 64f of the magnetic flux collecting portion 64a is further increased. Therefore, the magnetic flux collector 64a is not easily affected by the fluctuation of the magnetic field.

(Fifth and sixth embodiments)
The magnetism collecting ring is not limited to the semi-elliptical shape as in the above embodiment, but may be substantially triangular like the magnetism collecting rings 651 and 652 of the fifth embodiment shown in FIGS. In this case, the distance from the central axis O to the inner edge portion 65f is the maximum in the X direction and the minimum at a point 65h other than the Y direction. Moreover, polygonal shape may be sufficient like the magnetic flux collection rings 661 and 662 of 6th Embodiment shown to FIG.8 (c), (d). In this case, the distance from the central axis O to the inner edge portion 66f is maximum in the X direction and minimum in the Y direction.
In the fifth and sixth embodiments, the magnetic sensor 41 is located on the outer side from the axial projection of the pair of magnetic yokes 31 and 32. Note that the magnetic flux collecting portions 65a and 66a of the fifth and sixth embodiments are formed in an arc shape in the axial direction, like the magnetic flux collecting portion 61a of the first embodiment.

(Other embodiments)
(A) FIG. 9 shows an example of the shape of the magnetism collecting portion. In addition to (a) the arc-shaped magnetic flux collector 61a employed in the first embodiment and the like (excluding the second embodiment), (b) a pan-bottom magnetic flux collector 61b, and (c) a V-shaped magnetic flux collector. The magnetic part 61c, (d) a square groove-shaped magnetic collecting part 61d, and the like may be employed.
Since the magnetic flux collector 61c concentrates the magnetic flux at one point, the sensitivity of the magnetic sensor 41 is the best.
Since the magnetism collecting part 61d faces the magnetic sensor 41 in a plane, the robustness against the positional deviation of the magnetic sensor 41 in the direction orthogonal to the axial direction is improved.

  (A) FIG. 10 shows an arrangement example of the magnetism collecting ring. In the first embodiment and the like, as shown in FIG. 10A, the magnetism collecting rings 611 and 612 and the like are disposed substantially parallel to the magnetic yokes 31 and 32 in the yoke unit 30. On the other hand, as shown in FIG. 10B, the magnetism collecting rings 671 and 672 are inclined with respect to the magnetic yokes 31 and 32 so as to be separated from each other on the central axis O side and close to each other on the magnetic sensor 41 side. May be arranged. As a result, the magnetism collecting part and the magnetic sensor 41 can be brought into contact or as close as possible to each other only by forming a slight dent as the magnetism collecting part. Alternatively, the magnetism collecting portion may not be formed.

(C) FIG. 11 shows another embodiment of the magnetism collecting ring of the present invention.
The magnetism collecting rings 681 and 682 shown in FIGS. 11A and 11B have a “partial elliptical shape” that is smaller than the semi-elliptical shape (first embodiment). In this example, the distance from the central axis O to the inner edge portion 68f is the maximum in the X direction and is the minimum at the end point 68h of the inner edge portion 68f.
The magnetism collecting rings 691 and 692 shown in FIGS. 11C and 11D have a semi-elliptical shape (first embodiment) with a linear portion added to the opposite side of the magnetism collecting portion 69a. In this example, the distance from the central axis O to the inner edge 69f is the maximum in the X direction and the minimum in the Y direction.
Thus, for example, the shape of the magnetism collecting ring based on an elliptical shape may be any of a semi-elliptical shape, a shape smaller than a semi-ellipse, and a shape larger than a semi-ellipse.

Further, the magnetism collecting rings 701 and 702 shown in FIGS. 11E and 11F are substantially oval in which the outer edge shape expands in the X direction. The inner edge portion 70f has a substantially triangular shape (mushroom shape) rounded with the magnetic flux collecting portion 70a side as the apex, and the anti-magnetic flux collecting portion side is open. In this example, the distance from the central axis O to the inner edge portion 70f is the maximum in the X direction and the minimum at points other than the Y direction.
Note that the magnetic flux collecting portions 68a, 69a, and 70a of these magnetic flux collecting rings are formed in an arc shape in the axial direction, like the magnetic flux collecting portion 61a of the first embodiment.

(D) The magnetism collecting ring of the present invention is not limited to a semi-annular shape as in the above embodiment, and may be formed in an annular shape. For example, the magnetism collecting rings 711 and (712) shown in FIG. 12A have a semi-elliptical shape on the magnetism collecting portion 71a side of the central axis O and a semicircular shape on the anti-magnet collecting portion side in the X direction.
In the magnetism collecting rings 721 and (722) shown in FIG. 12B, a notch portion 72g is further formed in the X direction, and a magnetism collecting portion 72a is formed outside the notch portion 72g.

Further, in the magnetic flux collecting rings 731 and (732) shown in FIG. 13A, the magnetic flux collecting portion 73a side and the counter magnetic flux collecting portion side of the central axis O are both semi-elliptical in the X direction.
In the magnetic flux collecting rings 741 and 742 shown in FIG. 13B, the magnetic flux collecting portion 74a side and the counter magnetic flux collecting portion side of the central axis O are triangular in the X direction.
In the magnetic flux collecting rings 751 and 752 shown in FIG. 13C, with respect to the X direction, the magnetic flux collecting portion 75a side of the central axis O has a triangular shape, and the antimagnetic flux collecting portion side has a polygonal shape.

(E) In the above embodiment, the multipolar magnet 14 is fixed to the input shaft 11, and the pair of magnetic yokes 31 and 32 are fixed to the output shaft 12. The pair of magnetic yokes 31 and 32 may be fixed to the input shaft 11.
(F) The pair of magnetic yokes 31 and 32 are not integrally molded with resin, and the yoke unit 30 may not be configured. Further, the set of magnetism collecting rings 611 and 612 and the magnetic sensor 41 are not integrally molded with resin, and the sensor unit 40 may not be configured.

(G) 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.

2 ... Torque sensor,
11: Input shaft (first shaft),
12 ... Output shaft (second shaft),
13 ・ ・ ・ Torsion bar,
14 ... multipole magnet,
30 ... Yoke unit (integrated yoke member),
31, 32... A set of magnetic yokes,
31a, 32a ... nails,
34 ・ ・ ・ Groove,
41 ... Magnetic sensor,
611, 612 to 751, 752 ... a set of magnetism collecting rings (a set of magnetism collectors),
61a-75a, 61b-61d ... magnetism collecting part,
61f-70f ... inner edge part,
63g, 64g, 72g ... notch,
O ... central axis.

Claims (7)

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 multipolar magnet fixed to one end of the first shaft or the torsion bar;
A magnetic circuit is formed in the magnetic field generated by the multipolar magnet, fixed to the second shaft or the other end of the torsion bar outside the diameter of the multipolar magnet, and opposed in the axial direction through a gap. A set of magnetic yokes,
A set of sets for collecting magnetic flux from the set of magnetic yokes provided between the set of magnetic yokes in an axial direction so that at least a portion thereof overlaps with the set of magnetic yokes in an axial projection. With a magnetic body,
A magnetic sensor for detecting the strength of the magnetic field between the set of magnetic collectors;
With
The pair of magnetism collectors has a maximum distance from the central axis of the multipolar magnet to the inner edge in the X direction connecting the central axis of the multipolar magnet and the magnetic sensor. .   2. The torque sensor according to claim 1, wherein the pair of magnetic current collectors has a minimum distance from a central axis of the multipolar magnet to an inner edge portion in a Y direction orthogonal to the X direction.   3. The torque according to claim 2, wherein in the pair of magnetic current collectors, the distance from the central axis to the inner edge of the multipolar magnet increases continuously from the Y direction toward the X direction. Sensor.   The pair of magnetic current collectors is characterized in that a notch portion in which the distance from the central axis of the multipolar magnet to the inner edge portion is discontinuously increased from other regions is formed in the region including the X direction. The torque sensor according to any one of claims 1 to 3.   The pair of magnetic current collectors has an opening in a direction perpendicular to the axial direction, and is inserted between one radial side of the pair of magnetic yokes between the pair of magnetic yokes in the axial direction. The torque sensor as described in any one of Claims 1-4 characterized by these.   The pair of magnetic current collectors includes magnetic current collectors provided closer to each other in the axial direction than other portions of the magnetic current collectors, and the magnetic sensor is disposed between the magnetic current collectors. The torque sensor according to any one of claims 1 to 5. The set of magnetic yokes is integrally resin-molded to form a cylindrical integrated yoke member;
The torque sensor according to any one of claims 1 to 6, wherein a groove portion into which at least a part of the pair of magnetic current collectors is inserted is formed on a radially outer wall of the integrated yoke member.

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