JP2005156485A - Coil assembly for torque sensor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent mutual interference of a magnetic field between adjacent coils and a positional shift in the axial direction of a yoke block. <P>SOLUTION: A pair of yoke blocks 14A and 14B housing coils 7A and 7B is constructed of a bottomed cylindrical first yoke member 23 and a disk shaped second yoke member 24 fitted and fixed inside the inner circumference part on the opening side of the first yoke member 23, and the both blocks 14A and 14B are stored inside a housing while pressing stress in the axial direction is applied to them. In this coil assembly, the second yoke members 24 for the both blocks 14A and 14B are fitted to the first yoke members 23 so that the upper face of the second yoke member 24 is lower than the end face of the matching first yoke member 23, and the end faces of the first yoke members 23 for the both blocks 14A and 14B are brought into direct contact with each other so that a space part 43 is formed between the both blocks 14A and 14B. A spacer 44 formed of insulative resin is housed inside the space part 43. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a coil assembly of a torque sensor that detects an input torque from a change in impedance of a pair of coils.

  As a torque sensor, one described in Patent Document 1 has been developed.

  This torque sensor has a basic configuration in which a pair of shafts arranged coaxially are connected by a torsion bar, and the relative rotational position of both shafts according to torsion of the torsion bar is obtained from a change in coil impedance. These coils are surrounded by a yoke block and arranged on the outer peripheral side of the detected portion. A pair of yoke blocks having the same structure is provided to accommodate the coils, and both the yoke blocks are arranged in series in the axial direction and disposed in the concave portion of the housing.

In addition, a spacer made of an insulating material such as resin is interposed between both yoke blocks so that magnetic fields generated by the coils do not interfere with each other. Both yoke blocks and the spacer constitute a coil assembly, and the position is fixed in the concave portion in a state where one end side of the assembly is pressed by a disc spring.
JP 2000-2221086 A

  The coil assembly used in this torque sensor is fixed in the concave part with the spacer completely sandwiched between both yoke blocks, so the spacer is deformed by the pressure load of the disc spring, and the object to be detected There is a possibility that the positional relationship in the axial direction of the yoke block with respect to the portion changes. And if the position of the yoke block in the axial direction changes, there is a possibility that the torque detection accuracy is lowered.

  Therefore, the present invention provides a torque sensor coil assembly capable of improving detection accuracy by reliably preventing magnetic field interference between adjacent coils and axial displacement of the yoke block. It is what.

  As a means for solving the above-described problems, in the present invention, a pair of yoke blocks are fitted and fixed to a bottomed cylindrical first yoke member and an inner peripheral portion on the opening side of the first yoke member. It is composed of a disk-shaped second yoke member, and the two yoke blocks are assumed to be accommodated in the concave portion of the housing in a state where a pressing force is applied in the axial direction. At least one second yoke member is fitted into the first yoke member such that the upper surface thereof is lower than the corresponding end surface of the first yoke member on the opening side, and the second yoke member is disposed at a lower position. The end face of the first yoke member of one yoke block is brought into direct contact with the end face of the first yoke member of the other yoke block, and a space is formed between the second yoke member of one yoke block and the other yoke block. form It was way.

  In the case of this invention, at least one second yoke member is disposed at a lower position with respect to the end face of the first yoke member, and a space is formed between the second yoke member and the other yoke block. The magnetic fields generated by both coils are less likely to interfere with each other through the side surfaces of the yoke block. Further, since the first yoke members having high rigidity are in direct contact with each other in both yoke blocks, there is no problem that the yoke blocks are displaced in the axial direction even when a pressing force is applied.

  Further, as described in claim 2, a spacer made of an insulating material is disposed in the space portion, and the axial thickness of the spacer is set to be equal to or less than the height of the space portion in the axial direction. Anyway.

  In this case, interference of the magnetic fields of both coils can be effectively prevented by the spacer which is an insulating material. In addition, since the load that presses the yoke blocks does not act on the spacer, there is no problem that the position of the yoke block is shifted due to the deformation of the spacer.

  In the present invention, at least one second yoke member is disposed at a lower position with respect to the end surface of the first yoke member, and a space is formed between the second yoke member and the other yoke block. In addition, since the first yoke members having high rigidity are brought into direct contact with each other, the displacement of the yoke block in the axial direction can be reliably prevented. Therefore, according to the present invention, the detection accuracy of the torque sensor can be further improved.

  Next, each embodiment of the present invention will be described with reference to the drawings.

  First, the first embodiment shown in FIGS. 1 to 6 will be described. In this embodiment, the coil assembly 1 of a torque sensor according to the present invention is applied to a torque detection unit of a vehicle power steering apparatus, and the power steering apparatus has the following schematic configuration.

  That is, as shown in FIG. 2, the housing 2 supported and fixed to the vehicle body has a first shaft 3 on the steering wheel side and a second shaft 4 linked to a rack and pinion 20 that is a steering mechanism. The first shaft 3 and the second shaft 4 are connected via a torsion bar 5, and the torque acting between them is converted into the torsion amount of the torsion bar 5. ing. The worm wheel 6 that receives the power of the electric motor 21 is integrally attached to the second shaft 4, and the electric motor 21 generates an assist force according to the torque of the shafts 3 and 4. The torque sensor detects a change in the relative rotational position of the first and second shafts 3 and 4 accompanying the twist of the torsion bar 5 as a change in impedance of the coils 7A and 7B.

  The lower end portion of the first shaft 3 extends to the abutting portion with the second shaft 4 in a state of surrounding the torsion bar 5, and the reduced diameter portion 8 of the tip portion thereof is not in contact with the concave portion 9 on the upper surface of the second shaft 4. Has been inserted. The reduced diameter portion 8 of the first shaft 3 and the concave portion 9 of the second shaft are provided with stoppers (not shown) that restrict relative rotation of the shafts 3 and 4.

  The first and second shafts 3 and 4 are made of a magnetic metal, and a shielding member 11 having a substantially cylindrical shape as a whole is attached to the outer periphery on the lower end side of the first shaft 3 surrounding the torsion bar 5. ing. The shielding member 11 is a member that forms an inner magnetic path together with the outer peripheral portion on the lower end side of the first shaft 3, and is formed of a nonmagnetic and conductive metal material such as aluminum. A plurality of slits (not shown) along the axial direction are formed in the circumferential wall of the shielding member 11 at equal intervals in the circumferential direction, and a beam portion between adjacent slits forms a shielding region that blocks the passage of magnetic flux. Yes. Therefore, the shielding member 11 is formed by alternately forming a region having a large magnetic resistance and a region having a small magnetic resistance on the outer peripheral side of the first shaft 3 by a beam portion and a slit.

  On the other hand, a cylindrical member 13 is attached to the upper end portion of the second shaft 4 to surround the lower end side outer peripheral portion of the first shaft 3 and the outer peripheral side of the shielding member 11 in a non-contact state. The cylindrical member 13 is made of a non-magnetic and conductive metal material such as aluminum as in the case of the shielding member 11 described above, and there are as many rows of transmission windows (not shown) as the slits of the shielding member 11 on the peripheral wall. It is provided in two upper and lower stages. The transmission windows of each stage are arranged at equal intervals in the circumferential direction, and the transmission windows of both stages are offset from each other in the circumferential direction. In the neutral position where the torsion bar 5 is not twisted, the transmission windows of the respective stages overlap with the slits of the shielding member 11 by a half area on the left and right, and when the torsion bar 5 is twisted from this state, Depending on the amount of twist and the direction, the overlapping area with respect to the slits increases and decreases oppositely.

  Further, the coil assembly 1 according to the present invention including the coils 7A and 7B is disposed in a non-contact state on the outer peripheral side of each transmission window of the cylindrical member 13. In this coil assembly 1, a pair of yoke blocks 14 </ b> A and 14 </ b> B having the same structure that accommodates the coils 7 </ b> A and 7 </ b> B are superposed in the axial direction, and in this state, the coil assembly 1 is a biasing means in the concave portion 40 of the housing 2. The position is fixed by being pressed by the leaf spring 41. The energization cables 17a and 17b connected to the coils 7A and 7B are connected to a detection board 18 constituting an impedance detection circuit. The impedances of the coils 7A and 7B always increase or decrease by the same amount in the opposite direction whenever the torsion bar 5 is twisted due to the relationship between the opening areas of the upper and lower transmission windows. In the impedance detection circuit, the difference in impedance between the coils 7A and 7B is obtained, and the input torque is obtained based on the difference. Therefore, impedance changes due to factors other than the input torque such as temperature changes are canceled out.

  Here, the structure of the coil assembly 1 will be further described. Since both the yoke blocks 14A and 14B of the assembly 1 and the internal structure thereof are the same, only one yoke block 14B will be described in detail below. It shall be.

  As shown in FIGS. 1 and 3, the yoke block 14B is press-fitted and fixed to a bottomed cylindrical first yoke member 23 having a through hole 22 in the center and an inner peripheral portion on the opening side of the first yoke member 23. And a substantially disk-shaped second yoke member 24. Like the first yoke member 23, the second yoke member 24 has a through hole 25 in the center, and the detected portion such as the cylindrical member 13 is disposed in the through holes 22, 25 of the first and second yoke members 23, 24. Are inserted and arranged in a non-contact state.

  On the other hand, the coil 7B is wound around the outer periphery of the shaft portion of the resin bobbin 26, and the winding start end portion and the winding end end portion of the coil 7B are energized cables 17a and 17b at the outer edge portion of one flange 26a of the bobbin 26, respectively. It is connected to the.

  A substantially rectangular support block 28 is integrally formed on the outer peripheral edge of one flange 26a so as to protrude radially outward. The support block 28 protrudes upward with respect to the upper surface of the general portion of the flange 26a, and a pair of insertion holes 29 and 29 (see FIG. 4; one insertion hole in the same figure) penetrates the protruding portion in the radial direction. 29 is shown in parallel, and one end of a substantially L-shaped connection terminal 33 is press-fitted and fixed from the radially inner side to each insertion hole 29. Then, as shown in FIG. 4, the end of the winding start or end of winding of the coil 7B is connected to the tip of one end of the connection terminal 33 protruding from each insertion hole 29, and the other end of the connection terminal 33 is As shown in FIG. 3, the energization cable 17a (or 17b) is connected and held. The other end of the connection terminal 33 to which the energization cable 17a (or 17b) is connected is bent outward in the radial direction so as to form a straight line with one end of the connection terminal 33 as shown in FIG.

  Further, as shown in FIG. 1, a substantially rectangular notch 42 is formed at the opening edge of the first yoke member 23, and the bobbin 26 is accommodated in the first yoke member 23. The support block 28 protrudes outside the first yoke member 23 through the notch 42. The second yoke member 24 is press-fitted and fixed to the inner periphery of the end portion on the opening side of the first yoke member 23 in a state where the support block 28 is protruded to the outside through the notch 42. The second yoke member 24 is At this time, the upper surface is press-fitted so as to be lower than the end surface of the first yoke member 23 by the set height A. That is, the first yoke member 23 is covered with the second yoke member 24 in a state where the opening end is recessed in a state where the coil 7B and the bobbin 26 are accommodated therein.

  As described above, the yoke blocks 14A and 14B in which the coils 7A and 7B are respectively provided are overlapped so that the opening side end surfaces of the first yoke member 23 are in direct contact with each other. At this time, since the second yoke members 24 of both the yoke blocks 14A and 14B are recessed by the height A with respect to the end surfaces of the first yoke member 23, the second yoke members 24 and 24 of both the blocks 14A and 14B. A space 43 having a height of 2 × A is formed between them. The space 43 spatially separates the second yoke members 24, 24 of both blocks 14A, 14B, and prevents the magnetic fields generated by the coils 7A, 7B from interfering with each other.

  An annular spacer 44 made of resin, which is an insulating material, is accommodated in the space 43 formed between both yoke blocks 14A, 14B. The spacer 44 is formed in a substantially disc shape as a whole, and the outer diameter thereof is the same outer diameter as that of the second yoke member 24 (the same outer diameter as the inner diameter of the first yoke member 23). It is set to be the same as the axial height 2 × A or slightly lower than the axial height 2 × A.

  A holding block 45 is integrally formed on the outer peripheral edge of the spacer 44 as shown in FIGS. 1, 5, and 6. The holding block 45 includes an extended base 46 that extends radially outward from the disk-shaped main body of the spacer 44 and is disposed in the notch 42 of both yoke blocks 14A and 14B, and a front end of the extended base 46. Locking claws 47 (holding portions) projecting vertically on both side edges, a plate-like first insulating wall 48 extending further radially outward from the tip of the extending base portion 46, and the first insulation And a second insulating wall 49 projecting up and down from the center of the wall 48. The locking claw 47 and the first and second insulating walls 48 and 49 are arranged so as to protrude outward from the outer peripheral surfaces of the yoke blocks 14A and 14B, and the locking claw 47 has a hook 47a bent inward, The hooks 47a are engaged and held so as to hold the upper and lower support blocks 28,28. The first insulating wall 48 is disposed between the exposed portions of the connection terminals 33 protruding from the upper and lower support blocks 28, 28, and prevents the terminals of both the coils 7A, 7B from contacting each other and causing a short circuit. The second insulating wall 49 is disposed between the exposed portions of the connection terminals 33 and 33 discharged from each support block 28, and prevents the terminals on the winding start side and winding end side of the coils 7A and 7B from short-circuiting.

  As described above, the coil assembly 1 is provided with the yoke blocks 14A and 14B in which the bobbin 26 is accommodated, and as shown in FIG. 1, both the yoke blocks 14A and 14B are configured so as to accommodate the spacer 44 in the space 43. The end surfaces of the first yoke members 23, 23 are butted together. At this time, both the yoke blocks 14A and 14B are assembled while aligning the support block 28 protruding from the first yoke member 23 with the holding block 45 portion of the spacer 44, and each support block is attached to the locking claw 47 of the holding block 45. 28 is locked. The hook 47a of the locking claw 47 protrudes inward, and when the support block 28 is pushed in between the locking claws 47, 47 facing each other, the base portion side of the locking claw 47, 47 is elastically deformed and can be touched one time. The support block 28 can be pushed in. Accordingly, when the end faces of the first yoke members 23 and 23 are thus finished, the yoke blocks 14A and 14B are engaged with each other through the spacer 44 as shown in FIG.

  The coil assembly 1 configured as described above is positioned and fixed in the concave portion 40 of the housing 2 with the lower surface of the yoke block 14B pressed against the leaf spring 41, but the yokes arranged in series are arranged. Since the space portion 43 is provided between the second yoke members 24 and 24 of the blocks 14A and 14B, and the spacer 44 formed of an insulating resin is disposed in the space portion 43, each yoke block 14A and 14B is disposed. Magnetic fields generated by the inner coils 7A and 7B do not interfere with each other at the end of the second yoke member 24. Although avoidance of mutual interference of the magnetic fields can be achieved to some extent only by providing the space 43 between the adjacent second yoke members 24, 24, it is more reliable by interposing the resin spacer 44. It has become a thing.

  Further, in this coil assembly 1, since the end faces of the first yoke members 23, 23 of the yoke blocks 14A, 14B are in direct contact with each other, both the blocks 14A, 14B are affected even if the pressing force of the leaf spring 41 is received. Therefore, the detection accuracy of the torque sensor can always be maintained high. In particular, in the embodiment, since the axial thickness B of the spacer 44 is set to be 2 × A or less in the axial height of the space 44 between the both yoke blocks 14A, 14B, both the blocks 14A , 14B can be brought into contact with each other reliably. Since the pressing load of the leaf spring 41 does not act on the spacer 44, the spacer 44 is not deformed.

  Further, in the case of this coil assembly 1, since the spacer 44 is formed to have substantially the same outer diameter as the second yoke member 24, the spacer 44 is accommodated on the inner peripheral surface of the first yoke member 23 of both the yoke blocks 14A and 14B without rattling. There is an advantage that can be done.

  By the way, in this coil assembly 1, it is desirable to pass an electric current through the coils 7A and 7B so that the magnetic flux flows in the same rotational direction in both yoke blocks 14A and 14B. That is, in this assembly 1, since the end surfaces of the first yoke members 23 and 23 forming the outer peripheral walls of the yoke blocks 14A and 14B are in direct contact with each other, the current flows in this way in the yoke blocks 14A and 14B. The flow of magnetic flux can be made smooth.

  In the embodiment described above, the second yoke member 24 of both yoke blocks 14A, 14B is press-fitted and fixed so as to be lower than the end face of the first yoke member 23. However, the yoke block 14B (or 14A) on one side is fixed. Only the second yoke member 24) may be press-fitted so as to be low. Further, in this case, the end face of the first yoke member 23 of the yoke block 14B (or 14A) on the side where the second yoke member 24 is press-fitted low is used as the end face of the second yoke member 24 of the other yoke block 14A (or 14B). You may make it contact | abut to the end surface of the side which is not arrange | positioned. However, as in the above-described embodiment, the second yoke members 24 of both yoke blocks 14A and 14B are similarly press-fitted and the opening side end surfaces of the first yoke members 23 and 23 of both blocks 14A and 14B are brought into contact with each other. In this case, there is an advantage that the space 43 can be secured larger and the blocks 14A and 14B can have the same configuration.

  FIG. 7 shows a second embodiment of the present invention. The basic configuration of the coil assembly of this embodiment is substantially the same as that of the first embodiment described above, but is similar to the circumferential reciprocal position (position 180 ° apart) of the edge of the yoke block 14B (14A). Notches 42, 42 are formed, a pair of support blocks 28, 28 A formed on the bobbin 26 project outside the block 14 B (14 A) through the notches 42, 42, and the circumferential direction of the spacer 144 The point that the pair of holding blocks 45, 45A are integrally formed at the opposite positions is greatly different.

  One support block 28 protruding from the bobbin 26 and one holding block 45 of the spacer 144 are the same as in the first embodiment, and the other support block 28A and holding block 45A are the yoke block 14B (14A). And the spacer 144 are provided so that the engagement of the spacer 144 can be performed firmly and reliably. Further, since the yoke block 14B (14A) is a magnetic field path, it is preferable that the yoke block 14B (14A) has a uniform shape in the circumferential direction. In this embodiment, the yoke block 14B (14A) is equally spaced in the circumferential direction (every 180 °). ) Is provided with the notches 42, 42, so that the next time flowing in the yoke block can be balanced as compared with the case where only one notch is provided. In other words, the other support block 28A does not have a function of supporting the connection terminal 33 or the like, but is formed in a rectangular parallelepiped shape having substantially the same outer shape as the one, and the other holding block 45A engages the support block 28A. A locking claw 47 similar to the one holding block 45 is formed. When the yoke block 14B (14A) and the spacer 144 are assembled, the support blocks 28 and 28A are similarly locked by the locking claws 47 of the holding blocks 45 and 45A at the opposite positions in the circumferential direction.

  FIG. 8 shows a third embodiment of the present invention. The coil assembly of this embodiment is different from that of the first embodiment in that protective walls 50 are integrally formed on both ends of the holding block 245 of the spacer 244. The protective wall 50 extends to almost the same height as the locking claws 47 adjacent to both sides of the first insulating wall 48 of the holding block 245, and the side of the connection terminal 33 arranged on the first insulating wall 48 is almost completely. It is supposed to cover.

  Therefore, in this coil assembly, the protective wall 50 can prevent the exposed portion of the connection terminal 33 from coming into contact with the operator's hand or other members during assembly or maintenance work.

  Next, inventions other than those described in the claims that can be grasped from the above-described embodiment will be described together with the effects thereof.

  (A) The second yoke members of both yoke blocks are fitted to the first yoke member so that the upper surface thereof is lower than the end surface on the opening side of the first yoke member, and the openings of the first yoke members of both yoke blocks are fitted. 3. The torque sensor coil assembly according to claim 1, wherein the side end surfaces are brought into direct contact with each other, and a space is formed between the second yoke members of both yoke blocks.

  In this case, since the height of the space portion in the axial direction can be ensured, it is possible to more effectively reduce the mutual interference between the magnetic fields of both coils. Moreover, since both yoke blocks can be made into the same shape, it becomes possible to share the same component in both yoke blocks. Therefore, the manufacturing cost can be reduced.

  (B) A bobbin around which the coil is wound is accommodated in both yoke blocks together with the coil, and a support block that engages and supports a connection terminal that connects the coil end and the energization cable is provided integrally with the bobbin. A notch for projecting each support block radially outward is provided at the edge of the first yoke member of the yoke block, and a holding portion for holding both support blocks projecting through the notch is formed integrally with the spacer. The coil assembly for a torque sensor according to claim 2, wherein the coil assembly is a torque sensor.

  In this case, since the support block protruding radially outward from both yoke blocks can be held by the holding portion of the spacer, both yoke blocks can be integrated through the spacer and easily assembled to the housing in that state. .

  (C) The torque sensor coil assembly according to (b), wherein the spacer is integrally formed with an insulating wall that separates the connection terminals of both yoke blocks exposed from the support blocks.

  In this case, a short circuit due to direct contact between the connection terminals of both yoke blocks can be reliably prevented by the insulating walls of the spacer.

  (D) The torque sensor coil assembly according to (b) or (c) above, wherein the spacer is integrally formed with an insulating wall that separates connection terminals at both ends of the coil exposed from the support block. .

  In this case, it is possible to reliably prevent a short circuit due to the connection terminals on both ends of the coil coming into contact with each other by the insulating walls of the spacer.

  (E) A coil set for a torque sensor according to any one of (b) to (d) above, wherein a protective wall that covers the side of the connection terminal exposed from the support block is formed integrally with the spacer. Solid.

  In this case, since the side of the connection terminal is covered with the protective wall of the spacer, it is possible to eliminate the problem that the operator's hand or tool touches the connection terminal during assembly or maintenance work.

  (F) The coil assembly of the torque sensor according to claim 2, wherein the spacer is formed to have substantially the same outer diameter as the second yoke member.

  In this case, since the spacer is press-fitted into the inner peripheral surface of the first yoke member, it is possible to reliably eliminate the displacement and backlash of the spacer with respect to both yoke blocks.

  (G) The torque according to any one of claims 1 and 2, and (i) to (d), wherein a current is passed through each coil so that a magnetic flux flows through the yoke blocks in the same rotational direction. Sensor coil assembly.

  In this case, since the magnetic fluxes flowing on the outer peripheral sides of both yoke blocks are in the same direction, the flow of magnetic flux in both yoke blocks becomes smooth.

The exploded sectional view showing one embodiment of the present invention. The longitudinal cross-sectional view of the power steering device to which this invention is applied. The top view of the C arrow seen part of Drawing 1 showing one embodiment of the present invention. The perspective view at the time of the assembly | attachment of the D section of FIG. 3 which shows the same embodiment. The E arrow line view of FIG. 1 which shows the same embodiment. The perspective view which shows the same embodiment. The disassembled perspective view which shows the 2nd Embodiment of this invention. The perspective view which shows the 3rd Embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Coil assembly 7A, 7B ... Coil 14A, 14B ... Yoke block 23 ... 1st yoke member 24 ... 2nd yoke member 43 ... Space part 44, 144, 244 ... Spacer

Claims (2)

A pair of magnetic yoke blocks containing the coils inside are arranged in series in the axial direction, and the pair of yoke blocks are received in the concave portion of the housing with a pressing force applied in the axial direction. A coil assembly of a torque sensor that detects a change according to an input torque of a detected portion that penetrates the axial center of a block as an impedance change,
The yoke blocks are composed of a bottomed cylindrical first yoke member and a substantially disc-shaped second yoke member fitted and fixed to the inner peripheral portion on the opening side of the first yoke member. ,
The second yoke member on at least one side of the two yoke blocks is fitted to the first yoke member so that the upper surface thereof is lower than the end surface on the opening side of the corresponding first yoke member, and the second yoke member The end face of the first yoke member of one yoke block arranged at the lower position is brought into direct contact with the end face of the first yoke member of the other yoke block, so that the second yoke member of one yoke block and the other yoke block A coil assembly for a torque sensor, characterized in that a space is formed therebetween. 2. The torque sensor according to claim 1, wherein a spacer made of an insulating material is disposed in the space portion, and a thickness of the spacer in the axial direction is set to a thickness equal to or less than a height of the space portion in the axial direction. Coil assembly.

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