JP2008157762A - Torque-measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To facilitate a relative positioning of respective axis bodies and magnetically block magnetic fluxes flowing into a magnetic sensor from outside, without having to other magnetic members for magnetically blocking them, in assembling work. <P>SOLUTION: A magnetic body 32 having pawls 36, 38 is fixed to a first axis body 12 along with permanent magnets 26, 28, and a magnetic body 40 and magnetic bodies 42, 44 having claws I46, 48 are fixed to a second axis body 20, and a stator 52 having a U-shaped cross section is disposed on the outside of the magnetic bodies 40-44, and the magnetic sensor 54 is disposed on the inner circumference side of the stator 52. In the assembling work, the relative positioning of the first axis body 12 and the second axis body 20 can be facilitated, by merely mutually adjusting phases of the claws 36, 38 of the magnetic bodies 32, 34 and mutually adjusting phases of the claws 36, 38 of the magnetic bodies 32, 34, and for the magnetic sensor 54 disposed on the inner circumference side of the stator 52, the fluxes flowing from outside can be blocked magnetically, without having to use other magnetic members for blocking them magnetically. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a torque measuring device, for example, a torque measuring device for measuring torque generated on a rotating shaft of an automobile steering device or the like.

  Conventionally, for measuring torsional torque generated on a rotating shaft, for example, a first shaft connected to a steering wheel of an electric power steering device, and a first shaft connected to a first shaft through a connecting member are used. A relative displacement detector that detects relative displacement with a biaxial body has been proposed (see Patent Document 1). In this relative displacement detection device, a change in magnetic flux caused by a relative displacement between a permanent magnet fixed to the first shaft body and a pair of magnetic cores fixed to the second shaft body is detected with the first shaft body and the second shaft body. A configuration in which a magnetic sensor detects the relative position change direction and the displacement change amount around the rotation axis of the shaft body is adopted to improve durability.

  However, since the magnetic sensor is simply disposed in the space between one magnetic core and the other magnetic core, the magnetic flux generated between the magnetic cores also flows to a region other than the magnetic sensor, The magnetic flux cannot flow sufficiently.

Therefore, in order to allow a sufficient amount of magnetic flux to flow through the magnetic sensor, a ring-shaped auxiliary magnetic body (magnet collecting ring) is provided outside the pair of magnetic cores (magnetic yoke made of soft magnetic material), and the periphery of the auxiliary magnetic body is provided. It has been proposed that a magnetic flux collecting portion is provided in a part of the direction so that a magnetic flux generated from a magnet is intensively flowed from each magnetic core through a magnetic flux collecting portion of an auxiliary magnetic material (Patent Document 2). reference).
Japanese Patent Laid-Open No. 2-93321 JP 2003-149062 A

  However, in the one described in Patent Document 2, when arranging a magnet having multiple poles and a magnet having a plurality of claws facing the magnet, the torsion bar is not twisted, Although it is necessary to arrange the former magnetic poles so that the magnetic poles coincide with the boundary between the north and south poles of each of the latter magnets, the magnetic boundary position cannot be determined by the shape of the magnets. It was difficult to position. In addition, in both of Patent Documents 1 and 2, when a magnetic flux enters from the outside, the magnetic sensor detects the magnetic flux, so the magnetic sensor is surrounded by another magnetic member. They had to be magnetically shielded.

  The present invention has been made in view of the above-mentioned problems of the prior art, and its purpose is to facilitate positioning between the shaft bodies during assembly and without magnetic shielding with another magnetic member, The purpose is to shield magnetic flux flowing from the outside into the magnetic sensor.

  In order to achieve the above object, the present invention connects a first shaft body and a second shaft body rotatably supported by a housing, and the first shaft body and the second shaft body. An elastic body, an annular permanent magnet fixed to the first shaft body and magnetized along the axial direction of the first shaft body, and annularly formed at both magnetic pole ends of the permanent magnet; A plurality of first magnetic bodies fixed separately and formed in an annular shape and fixed to the second shaft body so as to be opposed to the permanent magnet and the first magnetic body while maintaining a certain gap. A plurality of second magnetic bodies arranged in a magnetic circuit including the permanent magnet, the first magnetic body, and the second magnetic body, and the first magnetic body and the second magnetic body. A magnetic sensor that detects changes in magnetic flux caused by relative displacement in the rotational direction of the magnetic material and a substantially cylindrical shape using a magnetic material And a plurality of first claws projecting in the axial direction toward the opposing first magnetic bodies on the outer periphery of each of the first magnetic bodies. An outer periphery of a pair of second magnetic bodies that are arranged along the circumferential direction and are divided on both sides so as to face each first magnetic body among the plurality of second magnetic bodies, A plurality of second claws projecting in the axial direction toward the second magnetic body facing each other are arranged along the circumferential direction, and each of the first claws and each of the second claws are arranged on the first axis. When one of the magnetic circuit area including the first claws and the magnetic circuit area including the second claws increases due to the relative angular displacement between the body and the second shaft body, the other decreases. And a second magnetic body intermediate between the pair of second magnetic bodies is disposed opposite to the magnetic sensor, and The sensor is disposed in the stator, and the stator is formed with an opening in a region connecting the magnetic sensor and the intermediate second magnetic body, and the first shaft body and the second shaft are formed. A torque measuring device for detecting a torque acting between the shaft body and a magnetic flux density passing through the magnetic sensor according to a relative displacement of the first claw and the second claw in the magnetic circuit is configured. It is a thing.

  According to the above configuration, the first shaft body can be obtained by adjusting the phases of the first claws of the first magnetic bodies to each other and adjusting the phases of the claws of the second magnetic bodies at the time of assembly. Since the magnetic sensor is arranged on the inner peripheral side of the stator, the magnetic sensor can be positioned without being shielded by another magnetic member. It is possible to magnetically shield the magnetic flux flowing in from the outside.

  When configuring the torque device, the cross section of the stator is formed in a U shape, and a magnetic material is disposed between the stator and the magnetic sensor, or the cross section of the stator is It can also be formed in a letter shape, a recess can be formed in a portion of the outer periphery of the stator opposite to the magnetic sensor, and the magnetic sensor can be arranged close to the recess. The permanent magnet may be composed of a plurality of ring-shaped magnets, or the permanent magnet may be composed of a single ring-shaped magnet, opposite to the second intermediate magnetic body at the center of the ring-shaped magnet. A ring-shaped first magnetic body can also be disposed. Furthermore, the permanent magnet can be formed of a resin-molded magnet and can be integrally formed with at least one of the first magnetic body and the second magnetic body.

  According to the present invention, it is possible to easily position the shafts at the time of assembly and to magnetically shield the magnetic flux flowing from the outside into the magnetic sensor without magnetically shielding with another magnetic member.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view of a torque measuring device showing a first embodiment of the present invention. In FIG. 1, the torque measuring device 10 includes a first shaft body 12 formed in a substantially cylindrical shape, and the first shaft body 12 is rotatably supported by a housing 16 via a bearing 14. Yes. The first shaft body 12 is connected at one end side in the axial direction to a steering wheel (not shown) of the electric power steering device, and the inner peripheral side at the other end in the axial direction is connected via an elastic body, for example, a torsion bar 18. The outer peripheral side of the other axial end is connected to a cylindrical non-magnetic body 22. The torsion bar 18, which is an elastic body, serves as a connecting member that connects the first shaft body 12 and the second shaft body 20. It is connected. The second shaft body 20 is rotatably supported by the housing 16 via a bearing 24.

  As shown in FIG. 2 (a), ring-shaped permanent magnets 26 and 28 are mounted on the outer peripheral surface of the cylindrical non-magnetic body 22, and the magnetic body (first disc) is formed in a substantially disc shape. Magnetic bodies) 30, 32, and 34 are mounted. The permanent magnets 26 and 28 are magnetized in the axial direction, and N and S poles are arranged along the axial direction. The magnetic body 30 is disposed between the permanent magnet 26 and the permanent magnet 28. The magnetic bodies 32 and 34 include a plurality of claws 36 and 38 projecting in the axial direction, and are arranged separately at both extreme portions of the permanent magnets 26 and 28. As shown in FIG. They are arranged at equal intervals along the circumferential direction while maintaining a phase difference of 180 ° from each other. The magnetic bodies 32 and 34 are arranged so that the claws 36 and 38 face each other, and each claw 36 and each claw 38 are attached to the N pole or the S pole according to the magnetic poles of the permanent magnets 26, 28, and 30. It is magnetized.

  The ring-shaped permanent magnets 26, 28 and the magnetic bodies 30, 32, 34 are opposed to each other, and the ring-shaped magnetic body (second magnetic body) is disposed around the permanent magnets 26, 28 and the magnetic bodies 30-34. 40 is arranged with a certain gap from the magnetic body 30, and ring-shaped magnetic bodies (second magnetic bodies) 42, 44 on both sides of the magnetic body 40 have a certain gap with the permanent magnets 26, 28. The arrangement is maintained (see FIG. 2B). The magnetic bodies 42 and 44 include a plurality of claws 46 and 48 protruding in the axial direction, and the claws 46 and 48 are arranged at equal intervals along the circumferential direction. The magnetic bodies 42 and 44 are arranged so that the claws 46 and 48 face each other, and the claws 46 and the claws 48 are arranged so that the phases in the circumferential direction are in phase. The magnetic bodies 40, 42, and 44 are connected to the second shaft body 20 via the bracket 50, and become permanent along with the relative rotation between the first shaft body 12 and the second shaft body 20. The magnets 26 and 28 and the magnetic body 30 are displaced along the circumferential direction. In this case, as shown in FIG. 4, when the claws 46 and the claws 48 move in the X direction with respect to the permanent magnets 26 and 28 and the magnetic body 30, the overlap of the N poles of the permanent magnets 26 and 28 increases. On the other hand, the overlap with the south pole is reduced, and the magnetic flux flows through the central magnetic body 40. That is, the claws 42 and 44 and the claws 46 and 48 are arranged such that the magnetic circuit area including the claws 42 and 44 and the claws 46 and 48 are changed by the relative angular displacement of the first shaft body 12 and the second shaft body 20. When one of the magnetic circuit areas including is increased, the other is decreased.

  Opposite to the magnetic bodies 40, 42, 44, an annular shape is formed around the magnetic bodies 40, 42, 44, and the stator 52 maintains a certain gap with the magnetic bodies 40, 42, 44. Has been placed. The stator 52 is made of a magnetic material and is fixed to the housing 16, and a plurality of magnetic sensors 54 are arranged on the inner peripheral side of the stator 52, as shown in FIGS. 2C and 5. Has been. The stator 52 surrounds each magnetic sensor 54 and forms an opening serving as a magnetic flux path in a region connecting each magnetic sensor 54 and the intermediate magnetic body 40. It is formed in a “U” shape.

  Each magnetic sensor 54 is arranged with a certain gap from a ring-shaped magnetic body 56 fixed to the inner peripheral side of the stator 52. The permanent magnets 26, 28 and the magnetic bodies 30, 32, 34 are fixed to the first shaft body 12, the magnetic bodies 40, 42, 44 are fixed to the second shaft body 20, and the stator 52 is fixed to the housing 16. FIG. 6 shows the assembled state when it is done.

  In the above configuration, when the torque from the first shaft body 12 does not act on the second shaft body 20 via the torsion bar 18, the magnetic bodies 32 and 34 are in the neutral state as shown in FIGS. The claws 46 and 48 of the magnetic bodies 42 and 44 are 90 degrees out of phase with respect to the N and S poles, which are the magnetic poles of the claws 36 and 38, respectively. . In this state, the magnetic overlap (magnetic resistance) between the N pole and the claw 46 by the claw 36 and the magnetic overlap (magnetic resistance) between the S pole and the claw 48 by the claw 38 are substantially equal. Since only the magnetic flux in the axial direction flows, no magnetic flux flows through the magnetic sensor 54 disposed in the center of the stator 52.

  On the other hand, the torque from the first shaft body 12 acts on the second shaft body 20 via the torsion bar 18, and for example, the second shaft body 20 has the first shaft as shown in FIG. When the shaft body 12 is displaced in the X direction, the magnetic overlap between the N pole and the claw 46 by the claw 36 increases, that is, the permeance indicating the ease of magnetic flow increases. Since the magnetic overlap reduction (permeance) between the S pole and the claw 48 due to 38 is reduced, the magnetic flux emitted from the N pole due to the claw 36 passes through the magnetic body 40 of the second shaft body 20 to the stator 52 side. To the magnetic sensor 54. This magnetic flux is detected by the magnetic sensor 54.

  On the other hand, the torque from the first shaft body 12 acts on the second shaft body 20 via the torsion bar 18, and for example, the second shaft body 20 is shown in FIG. When deviating in the direction opposite to the X direction shown, the magnetic overlap (magnetic resistance) between the N pole and the claw 46 by the claw 36 decreases, and conversely, the magnetic overlap between the S pole and the claw 48 by the claw 38 ( Therefore, the magnetic flux emitted from the south pole by the claw 38 flows from the magnetic body 40 of the second shaft body 20 to the stator 52 side through the magnetic sensor 54. This magnetic flux is detected by the magnetic sensor 54.

  With the above operation, as shown in FIG. 7, the magnetic flux (magnetic flux density) flowing through the magnetic sensor 54 changes in accordance with the relative angular displacement between the first shaft body 12 and the second shaft body 20. When the torque from the shaft body 12 does not act on the second shaft body 20 via the torsion bar 18, in the neutral state, the magnetic flux penetrating the magnetic sensor 54 becomes zero, and the torque from the first shaft body 12 becomes torsion. When acting on the second shaft body 20 via the bar 18 and the second shaft body 20 is displaced in the X direction with respect to the first shaft body 12, the polarity of the magnetic flux penetrating the magnetic sensor 54 and When the second shaft body 20 is displaced in the direction opposite to the X direction with respect to the first shaft body 12, the polarities of the magnetic fluxes penetrating the magnetic sensor 54 are opposite to each other.

  Thereby, the magnetic sensor 54 can detect the torque acting between the first shaft body 12 and the second shaft body 20 by a change in magnetic flux penetrating the magnetic sensor 54.

  According to the present embodiment, at the time of assembly, the phases of the claws 36 and 38 of the magnetic bodies 32 and 34 are adjusted to each other, and the phases of the claws 46 and 48 of the magnetic bodies 42 and 44 are adjusted to each other. The shaft body 12 and the second shaft body 20 can be easily positioned with each other, and the magnetic sensor 54 is disposed on the inner peripheral side of the stator 52 having a U-shaped cross section. Without magnetically shielding the magnetic sensor 54 with the magnetic member, the magnetic flux flowing from the outside into the magnetic sensor 54 can be magnetically shielded.

  The claws 36 and 38 of the magnetic bodies 32 and 34 and the claws 46 and 48 of the magnetic bodies 42 and 44 are quadrangular in the embodiment, but may be triangular as in the case of a claw pole motor. it can.

  Further, when the magnetic sensor 54 is disposed on the stator 52, as shown in FIG. 8, a configuration is adopted in which a concave portion 58 is provided on the outer peripheral side of the stator 52 and the magnetic sensor 54 is disposed on the inner peripheral side of the concave portion 58. You can also In this case, magnetic flux can be collected in the magnetic sensor 54 without using the magnetic body 56, and the number of parts can be reduced.

Next, a second embodiment of the present invention will be described with reference to FIG. In the present embodiment, a ring-shaped permanent magnet 60 is used instead of the ring-shaped permanent magnets 26 and 28, a ring-shaped magnetic body 62 is used instead of the magnetic body 30, and other configurations are as follows. The same as in the first embodiment.
The permanent magnet 60 is configured as a resin-molded magnet, and the ring-shaped magnetic body 62 is disposed at a substantially central portion of the outer peripheral surface of the permanent magnet 60. FIG. 10 shows a state in which the permanent magnet 60 and the magnetic bodies 32, 34, 62 are developed in the circumferential direction, FIG. 11 shows a state in which the magnetic bodies 40, 42, 44 are deployed in the circumferential direction, and FIG. FIG. 12 shows the state, and FIG. 13 shows the assembled state of each part.

  When the permanent magnet 60 is configured as a resin-molded magnet, the magnetic bodies 32 and 34 having the claws 36 and 38 are integrally molded, and the magnetic body 62 is integrally molded at the substantially central portion of the outer peripheral surface of the permanent magnet 60. Thus, the number of parts at the time of assembly can be reduced and the assembly work can be facilitated. When the magnetic bodies 32, 34, and 62 are integrally formed on the permanent magnet 60, the permanent magnet 60 and the magnetic bodies 32, 34, and 62 can be magnetized from the axial direction after the molding.

  According to the present embodiment, at the time of assembly, the phases of the claws 36 and 38 of the magnetic bodies 32 and 34 are adjusted to each other, and the phases of the claws 46 and 48 of the magnetic bodies 42 and 44 are adjusted to each other. The shaft body 12 and the second shaft body 20 can be easily positioned with each other, and the magnetic sensor 54 is disposed on the inner peripheral side of the stator 52 having a U-shaped cross section. Without magnetically shielding the magnetic sensor 54 with the magnetic member, the magnetic flux flowing from the outside into the magnetic sensor 54 can be magnetically shielded.

  Further, according to the present embodiment, since the single permanent magnet 60 is fixed to the first shaft body 12, the number of parts can be reduced as compared with the first embodiment.

  In this embodiment, members for fixing the magnetic bodies 32, 34, 62 are omitted, but when the magnetic bodies 32, 34, 62 are integrally molded with the permanent magnet 60 with resin, Each magnetic body 32, 34, 62 can be fixed with resin. Of course, not only the resin but also each magnetic body 32, 34, 62 can be incorporated into a non-magnetic body such as plastic or aluminum to form an integrated structure.

  In a vehicle equipped with an electric power steering device, when steering control is performed using a torque measuring device as a torque sensor, in the unlikely event that the torque sensor fails, steering control cannot be performed with a single torque sensor. As in each of the above embodiments, a plurality of, for example, two magnetic sensors 54 are arranged on the stator 52 to form a double system, thereby ensuring reliability. In this case, in order to further improve the accuracy of reliability, the magnetic sensor 54 can be further added.

  In each of the above-described embodiments, the measurement of the torque generated on the rotating shaft of an automobile steering or the like has been described. However, the present invention relates to the torque generated on the rotating shaft of various rotating machine devices or the torque generated on the stationary shaft. It can also be applied to what is measured.

It is sectional drawing of the torque measuring device which shows 1st Example of this invention. (A) is an exploded perspective view of the permanent magnet and the magnetic body fixed to the first shaft body, (b) is an exploded perspective view of the magnetic body fixed to the second shaft body, and (c) is It is a perspective view of a stator. (A) is sectional drawing of the permanent magnet and magnetic body which are fixed to the 1st shaft, (b) is the development view of the permanent magnet and magnetic which are fixed to the 1st shaft. It is. (A) is sectional drawing of the magnetic body fixed to the 2nd shaft body, (b) is a development view of the magnetic body fixed to the 2nd shaft body. (A) is sectional drawing of a stator, (b) is an expanded view of a stator. It is sectional drawing which shows the assembly state of the torque measuring device of 1st Example. It is a characteristic view which shows the relationship between the relative angular displacement of a 1st shaft body and a 2nd shaft body, and magnetic flux density. (A) is principal part sectional drawing which shows the other Example of a stator, (b) It is a principal part expanded sectional view which shows the other Example of a stator. It is sectional drawing of the torque measuring device which shows 2nd Example of this invention. (A) is a sectional view of the permanent magnet and the magnetic body fixed to the first shaft body in the second embodiment, and (b) is a permanent magnet fixed to the first shaft body in the second embodiment. It is an expanded view of a magnetic body. (A) is sectional drawing of the magnetic body fixed to the 2nd shaft body in 2nd Example, (b) is a development view of the magnetic body fixed to the 2nd shaft body in 2nd Example. is there. (A) is sectional drawing of the stator in 2nd Example, (b) is a development view of the stator in 2nd Example. It is sectional drawing which shows the assembly state of the torque measuring device of 2nd Example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Torque measuring device 12 1st shaft body 18 Torsion bar 20 2nd shaft body 26, 28, 30 Permanent magnet 32, 34 Magnetic body 36, 38 Claw 40, 42, 44 Magnetic body 46, 48 Claw 52 Stator 54 Magnetic sensor 58 Recess 60 Permanent magnet 62 Magnetic body

Claims (6)

A first shaft body and a second shaft body rotatably supported by a housing, an elastic body connecting the first shaft body and the second shaft body, and fixed to the first shaft body An annular permanent magnet that is magnetized along the axial direction of the first shaft body, and a plurality of first magnetic bodies that are formed in an annular shape and are divided and fixed at both magnetic pole ends of the permanent magnet A plurality of second magnetic bodies formed in an annular shape and fixed to the second shaft body and arranged opposite to each other while maintaining a certain gap with the permanent magnet and the first magnetic body; The magnetic flux generated by the relative displacement in the rotational direction of the first magnetic body and the second magnetic body is disposed in a magnetic circuit including the permanent magnet, the first magnetic body, and the second magnetic body. A magnetic sensor that detects changes and a substantially cylindrical shape using a magnetic material and fixed to the housing And a stator,
A plurality of first claws protruding in the axial direction toward the opposing first magnetic bodies are arranged along the circumferential direction on the outer periphery of each of the first magnetic bodies, and the plurality of second magnetic bodies The outer periphery of a pair of second magnetic bodies arranged on both sides opposite to each first magnetic body of the body protrudes in the axial direction toward the opposing second magnetic bodies A plurality of second claws are arranged along the circumferential direction, and each of the first claws and each of the second claws is moved by the relative angular displacement between the first shaft body and the second shaft body. When one of the magnetic circuit area including the first claws and the magnetic circuit area including the second claws increases, the other is decreased, and the intermediate circuit between the pair of second magnetic bodies The magnetic body 2 is disposed opposite to the magnetic sensor, the magnetic sensor is disposed in the stator, and the stator includes: Opening is formed in a region connecting the serial magnetic sensor and a second magnetic body of the intermediate,
The torque acting between the first shaft body and the second shaft body is a magnetic flux penetrating the magnetic sensor in accordance with the relative displacement of the first claw and the second claw in the magnetic circuit. Torque measuring device that detects changes in density.   The torque measurement according to claim 1, wherein the stator has a U-shaped cross section, and a magnetic body is disposed between the stator and the magnetic sensor. vessel.   The stator has a U-shaped cross section, and a recess is formed in a portion of the outer periphery of the stator opposite to the magnetic sensor, and the magnetic sensor is disposed close to the recess. The torque measuring device according to claim 1, wherein   The torque measuring device according to claim 1, wherein the permanent magnet includes a plurality of ring-shaped magnets.   The permanent magnet is composed of a single ring-shaped magnet, and a ring-shaped first magnetic body is disposed opposite to the intermediate second magnetic body at the center of the ring-shaped magnet. The torque measuring device according to any one of claims 1 to 3, wherein   6. The permanent magnet according to claim 1, wherein the permanent magnet is a resin-molded magnet and is integrally formed with at least one of the first magnetic body and the second magnetic body. Torque measuring instrument.

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