JP2008232981A - Torque sensor and electric power steering system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a torque sensor including a magnetic flux intensity detecting means, capable of more correct detection of torque than conventional ones and further size reduction, as compared with conventional types, when the function of detecting a rotation position of a torsion bar is provided, and an electric power steering system including the torque sensor. <P>SOLUTION: The torque sensor 10 has first to third magnetic path component members 35S, 36S and 37S for constituting a magnetic path between a first and second rotary magnets 31 and 32 and Hall elements 35H, 36H and 37H for detecting intensity of magnetic fluxes passing through them, which are fixed together to a carry housing 11. Thus, the problem wherein a gap varies and the problem wherein the magnetic flux intensity drops as in a conventional torque sensor can be solved, thereby the torque is accurately detected. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a torque sensor for detecting torque based on torsion of a torsion bar rotatably supported by a support housing, and an electric power steering apparatus including the torque sensor.

  Conventionally, as this type of torque sensor, a sensor capable of detecting a torque by detecting a shift in rotational positions of both end portions of a torsion bar with a pair of resolvers to obtain torsion of the torsion bar (for example, Patent Document 1). As another conventional example, a torque sensor including a magnetic flux intensity detecting means such as a Hall element is also known. As an example, the torque sensor shown in FIG. 13 includes a cylindrical rotating magnet 4 that rotates integrally with one end of the torsion bar 1, and the other end of the torsion bar 1 that surrounds the rotating magnet 4 from the side. First and second ring yokes 5 and 6 that rotate together are provided.

  As shown in FIG. 14, the first ring yoke 5 has a structure in which a plurality of triangular projecting pieces 5A protrude in the axial direction from the annular portion 5B, and the second ring yoke 6 has a plurality of axial projections from the annular portion 6B. The triangular projecting piece 6A is projected. These triangular protrusions 5A and 6A are arranged in the circumferential direction with a gap alternately as shown in FIG. Moreover, as shown in FIG. 13, between the annular parts 5B and 6B, the Hall element 7 is disposed with a gap with respect to the annular parts 5B and 6B. The Hall element 7 is fixed to a support housing (not shown) that rotatably supports the torsion bar 1, and the magnetic flux between the annular portions 5B and 6B at an arbitrary position in the circumferential direction of the annular portions 5B and 6B. The intensity can be detected.

As shown in FIG. 14, the rotating magnet 4 is polarized into a plurality of magnetic poles in the circumferential direction, and in a state where the torsion bar 1 is not twisted, as shown in FIG. , 6A is opposed to the boundary between adjacent magnetic poles of the rotating magnet 4. When the torsion bar 1 is twisted to one side, as shown in FIG. 15A, the center of the triangular protruding piece 5A faces the N magnetic pole of the rotating magnet 4 and the center of the triangular protruding piece 6A is the rotating magnet 4's center. When the torsion bar 1 is twisted to the other side while facing the S magnetic pole, the center of the triangular protrusion 5A faces the S magnetic pole of the rotating magnet 4 and the triangular protrusion as shown in FIG. The center of 6A faces the N magnetic pole of the rotating magnet 4. As a result, the magnetic flux intensity detected by the Hall element 7 changes according to the twist of the torsion bar 1, and the torque can be detected based on the change (see, for example, Patent Document 2).
JP 2004-294265 A (paragraphs [0018] to [0041], FIG. 1) JP 2003-149062 (paragraphs [0034] to [0041], FIG. 1, FIG. 2, FIG. 4)

  However, in the conventional torque sensor provided with the above-described magnetic flux intensity detection means, when the annular portions 5B and 6B rotate together with the torsion bar 1, the gap between the annular portions 5B and 6B and the Hall element 7 varies, and the accurate The torque could not be detected. Further, in order for the Hall element 7 to detect the magnetic flux intensity at an arbitrary position in the circumferential direction of the annular portions 5B and 6B, it is necessary to make the magnetic flux uniform throughout the circumferential direction of the annular portions 5B and 6B. It was. For this reason, the magnetic flux passed through the Hall element 7 is reduced, and even in this respect, the torque cannot be accurately detected.

  In addition, in the conventional torque sensor using the resolver described above, when the function of detecting the rotational position of the torsion bar is added, the detection result of the resolver can be used. In the conventional torque sensor, the detection result of the magnetic flux intensity detection means cannot be used to detect the rotational position of the torsion bar. For this reason, when the function to detect the rotational position of the torsion bar is added, there is a problem that the whole size increases.

  The present invention has been made in view of the above circumstances, and in a torque sensor provided with magnetic flux intensity detection means, it is possible to detect torque more accurately than in the prior art and to have a function of detecting the rotational position of a torsion bar. Another object of the present invention is to provide a torque sensor that can be made smaller than before and an electric power steering apparatus including the torque sensor.

  In order to achieve the above object, a torque sensor (10) according to the invention of claim 1 detects torque based on the twist of a torsion bar (14) rotatably supported by a support housing (11). In the first torque sensor (10), the first rotation is a circle centered on the torsion bar (14), equally divided into a plurality of magnetic poles in the circumferential direction, and rotated integrally with one end of the torsion bar (14). The magnet (31) has a circular shape centered on the torsion bar (14), is equally divided in the circumferential direction into the same number of magnetic poles as the first rotating magnet (31), and is integrated with the other end of the torsion bar (14). The second rotating magnet (32) rotating in the direction and the magnetic path constituting member (35S) which is fixed to the support housing (11) and forms a magnetic path between the first and second rotating magnets (31, 32) , 36S, 37 ) And a magnetic path constituting member (35S, 36S, 37S), and can be opposed to each magnetic pole of the first rotating magnet (31) according to the rotational position of the first rotating magnet (31). One magnetic pole facing portion (35B, 36B, 37B) and a magnetic path constituting member (35S, 36S, 37S) are formed on the second rotating magnet (32) according to the rotational position of the second rotating magnet (32). Magnetic flux intensity detecting means for detecting the intensity of the magnetic flux passing through the second magnetic pole facing portion (35B, 36B, 37B) and the magnetic path constituting member (35S, 36S, 37S) that can face each magnetic pole of (32). (35H, 36H, 37H).

  According to a second aspect of the present invention, in the torque sensor (10) according to the first aspect, the magnetic path constituent member (35S, 36S, 37S) has a pair of annular portions (35A centered on the torsion bar (14)). , 36A, 37A), and spaced at an integral multiple of one cycle of the electrical angle of the first rotating magnet (31) at a plurality of positions along the circumferential direction of one of the annular portions (35A, 36A, 37A). A plurality of first magnetic pole facing portions (35B, 36B, 37B) are arranged, and the second rotating magnet (32) is disposed at a plurality of positions along the circumferential direction of the other annular portion (35A, 36A, 37A). It is characterized in that a plurality of second magnetic pole facing portions (35B, 36B, 37B) are arranged at intervals of an integral multiple of one electrical angle cycle.

  According to a third aspect of the present invention, in the torque sensor (10) according to the first or second aspect, the magnetic path constituent member (35S, 36S, 37S) are provided, and the detection results of the three magnetic flux intensity detecting means (35H, 36H, 37H) provided in the three magnetic path constituent members (35S, 36S, 37S) can be output. Has characteristics.

According to a fourth aspect of the present invention, in the torque sensor (10) according to the third aspect, when the detection results of the three magnetic flux intensity detecting means (35H, 36H, 37H) are V1, V2, and V3,

  And a signal processing unit (39) for calculating a torque based on the magnitude relationship between the calculated value S and a predetermined reference value.

  According to a fifth aspect of the present invention, in the torque sensor (10) according to any one of the first to fourth aspects, the first and second magnetic pole facing portions (35B, 36B, 37B) are arranged around the torsion bar (14). It is characterized in that the first and second rotating magnets (31, 32) are arranged to be shifted by an electrical angle ¼ period in the same phase and the torsion bar (14) is not twisted.

  The invention of claim 6 is the torque sensor (10) according to any one of claims 1 to 5, wherein a plurality of magnetic path constituent members (35S, 36S, 37S) are provided, and the plurality of magnetic path constituent members (35S, A plurality of SIN curves (g1, g2, g3) having a phase difference when the detection results of the plurality of magnetic flux intensity detecting means (35H, 36H, 37H) provided for each of 36S, 37S) rotate the torsion bar (14). ), A plurality of magnetic path constituent members (35S, 36S, 37S) are arranged, and the torsion bar (14) is detected from the detection results of the plurality of magnetic flux intensity detecting means (35H, 36H, 37H). It is characterized in that the electrical angle can be detected.

  A seventh aspect of the present invention is the torque sensor (10) according to the sixth aspect, wherein the torque sensor (10) has a circular shape centered on the torsion bar (14) and is different from the number of magnetic poles of the first and second rotating magnets (32). The sub-rotating magnets (21, 22) that are equally divided in the circumferential direction and rotated integrally with the torsion bar (14) and the rotation of the sub-rotating magnets (21, 22) are fixed to the support housing (11). A plurality of sub magnetic path constituent members (25S, 26S, 27S) and a plurality of sub magnetic path constituent members (25S, 26S, 27S) that can be opposed to the magnetic poles of the sub rotating magnets (21, 22) according to the position. And a plurality of sub magnetic flux intensity detecting means (25H, 26H, 27H) for detecting the magnetic flux intensity of the sub rotating magnets (21, 22) passing through the plurality of sub magnetic flux intensity detecting means (25H, 26H, 27H A plurality of sub magnetic path constituent members (25S, 26S, 27S) are arranged so as to draw and change a plurality of SIN curves having a phase difference when the detection result of the rotation of the torsion bar (14), The electrical angle of the torsion bar (14) can be detected from the detection results of the plurality of sub magnetic flux intensity detection means (25H, 26H, 27H), and the calculation results of the plurality of sub magnetic flux intensity detection means (25H, 26H, 27H) Based on the combination of the electrical angle of the torsion bar (14) detected and the electrical angle of the torsion bar (14) detected by the calculation results of the plurality of magnetic flux intensity detection means (25H, 26H, 27H) 14) It is characterized in that the mechanical angle can be detected.

  An electric power steering apparatus (50) according to an eighth aspect of the present invention includes the torque sensor (10) according to any one of the first to seventh aspects for detecting a steering resistance of the handle (60). Has characteristics.

[Invention of Claim 1]
In the configuration of claim 1, when the first and second rotating magnets rotate together with the torsion bar, the first and second magnetic pole facing portions formed on the magnetic path constituent member of the first and second rotating magnets, and The opposite position of changes. As a result, the intensity of the magnetic flux passing through the magnetic path constituting member changes with the rotation of the torsion bar, and the detection result of the magnetic flux intensity detecting means changes in a SIN curve. Further, when the torsion bar is twisted, the first and second rotating magnets are relatively rotated, and the opposing states of the first and second magnetic pole facing portions with respect to the first and second rotating magnets are changed. The amplitude value of the SIN curve changes. Then, the twist amount of the torsion bar is obtained based on the change in the amplitude value of the SIN curve, and the torque can be detected based on the twist amount.

  In the torque sensor of the present invention, the magnetic path constituting member constituting the magnetic path between the first and second rotating magnets is fixed to the support housing. Thereby, the magnetic flux intensity detection means for detecting the intensity of the magnetic flux passing through the magnetic path constituting member can also be fixed to the support housing, and the problem of gap variation and the decrease of the magnetic flux intensity as in the past are solved. Torque can be detected accurately.

[Invention of claim 2]
According to the configuration of the second aspect, since the first and second magnetic pole facing portions facing the first and second rotating magnets are provided in plural, the first and second magnetic pole facing portions and the first and second magnetic pole facing portions are provided. A wide area facing the second rotating magnet can be secured. As a result, a large amount of the magnetic flux of the first and second rotating magnets can be taken into the magnetic path constituting member, the magnetic flux strength detection accuracy is improved, and the torque detection accuracy is also improved.

[Inventions of Claims 3 and 4]
In the configuration of claim 3, three magnetic path constituent members are provided by shifting the phase of the first rotary magnet by an electrical angle of 1/3 period, and three magnetic flux intensity detections respectively provided in the three magnetic path constituent members are provided. Since the detection result of the means can be output, the amplitude value in the SIN curve of the detection result of the magnetic flux intensity detection means can be obtained without rotating the torsion bar.

  Specifically, when the detection results of the three magnetic flux intensity detection means are V1, V2, and V3 as in the configuration of claim 4,

  The amplitude value can be calculated as the calculation value S. Then, the torque can be obtained based on the magnitude relationship between the calculated value S and a predetermined reference value.

[Invention of claim 5]
According to the configuration of the fifth aspect, the first and second magnetic pole opposing portions are arranged in the same phase around the torsion bar, and the first and second rotating magnets are electrically angled with the torsion bar not twisted. Since the arrangement is shifted by ¼ period, whether the torsion bar is twisted to one side or the other depending on whether the amplitude value is larger or smaller than the amplitude value of the SIN curve when the torsion bar is not twisted Can be determined.

[Inventions of Claims 6 and 7]
According to the configuration of claim 6, the electrical angle of the torsion bar can be detected from the detection results of the plurality of magnetic flux intensity detecting means, and the electrical angle can be used to detect the mechanical angle of the torsion bar. it can. Thereby, when the function which detects the rotation position of a torsion bar is added, the whole torque sensor can be reduced in size.

  Specifically, as in the configuration of the seventh aspect, a sub-rotating magnet having a plurality of magnetic poles different from the first and second rotating magnets is provided and is opposed to each magnetic pole of the sub-rotating magnet. If a plurality of possible sub magnetic path constituent members are fixed to the support housing and the magnetic flux intensity of the sub rotating magnet passing through the plurality of sub magnetic path constituent members is detected by a plurality of sub magnetic flux intensity detecting means, the sub magnetic flux intensity detection is performed. The mechanical angle of the torsion bar can be calculated based on a combination of two kinds of electrical angles, that is, the electrical angle of the torsion bar detected by the means and the electrical angle of the torsion bar detected by the magnetic flux intensity detecting means.

[Invention of Claim 8]
Since the electric power steering apparatus according to the eighth aspect is equipped with the torque sensor capable of detecting the torque more accurately than the conventional one for detecting the steering resistance of the steering wheel as described above, the output of the electric power steering apparatus is accurately controlled. be able to.

  Hereinafter, embodiments according to the present invention will be described with reference to FIGS. FIG. 1 shows the entire torque sensor 10 of the present embodiment. In the figure, reference numeral 11 denotes a support housing having a cylindrical structure with both ends open, and a rotating shaft portion 12 passes through the inside thereof.

  The rotating shaft portion 12 includes a torsion bar 14 and first and second extension sleeves 15 and 16. In the torsion bar 14, the diameter of the intermediate portion 14C is smaller than that of both end portions 14A and 14B, and when the load torque is received, the intermediate portion 14C is twisted and deformed.

  The first extension sleeve 15 covers from one end portion 14A of the torsion bar 14 (hereinafter referred to as “base end portion 14A”) to an intermediate position in the axial direction. On the other hand, the second extension sleeve 16 covers from the other end 14B of the torsion bar 14 (hereinafter referred to as the “tip 14B”) to an intermediate position in the axial direction. The ends of the first and second extension sleeves 15 and 16 are opposed to each other with a gap in the axial direction at the central portion in the axial direction of the torsion bar 14.

  The first extension sleeve 15 is pin-coupled to the base end portion 14A of the torsion bar 14 and loosely fitted to the intermediate portion 14C. As a result, the first extension sleeve 15 rotates integrally with only the base end portion 14 </ b> A of the torsion bar 14. On the other hand, the second extension sleeve 16 is splined to the distal end portion 14B of the torsion bar 14 and loosely fitted to the intermediate portion 14C. As a result, the second extension sleeve 16 rotates integrally with only the distal end portion 14B of the torsion bar 14. A pair of bearings 13, 13 provided at both ends of the support housing 11 are fitted to the outer peripheral surface of the first extension sleeve 15 and the outer peripheral surface of the second extension sleeve 16, respectively. The whole is rotatably supported with respect to the support housing 11.

  In addition, the pin coupling | bond part with the torsion bar 14 among the 1st extension sleeves 15 is exposed to the outer side of the support housing 11, and the spline part 15S is formed in the outer peripheral surface. The second extension sleeve 16 has a structure in which a pinion gear 16G is integrally provided on the extension of the tip portion 14B of the torsion bar 14.

  A part of the first extension sleeve 15 includes first and second sub-rotating magnets 21 and 22 and a first rotating magnet 31. A part of the second extension sleeve 16 is constituted by a second rotating magnet 32. The first and second sub-rotating magnets 21 and 22 and the rotating magnets 31 and 32 are all in the shape of a hollow disk having the same shape. The first and second extension sleeves 15 and 16 are entirely made of a non-magnetic material except for the first and second sub-rotating magnets 21 and 22 and the rotating magnets 31 and 32.

  More specifically, for example, a portion of the first extension sleeve 15 that covers the intermediate portion 14C of the torsion bar 14 is formed with a small-diameter portion 15A extending from the axial tip to the intermediate portion. The first sub-rotating magnet 21, the spacer 15B, the second sub-rotating magnet 22, the spacer 15C, and the first rotating magnet 31 are sequentially fitted to the small-diameter portion 15A and fixed with an adhesive. .

  A small diameter portion 16A is also formed at the tip of the second extension sleeve 16 on the first extension sleeve 15 side, and the second rotary magnet 32 is fitted into the second extension sleeve 16A and fixed with an adhesive. Has been. As a result, the first and second sub-rotating magnets 21 and 22 and the first and second rotating magnets 31 and 32 are arranged at intervals in four locations in the axial direction of the rotating shaft portion 12. Yes.

  As shown in FIG. 2, the first and second rotating magnets 31 and 32 are equally divided into magnetic poles (S pole, N pole) of a predetermined even number m (for example, m = 6) in the circumferential direction. When the torsion bar 14 is not twisted and deformed, the boundary between the adjacent N magnetic pole and S magnetic pole in the first rotating magnet 31 is at the center of the N magnetic pole and S magnetic pole in the second rotating magnet 32. Opposite. That is, the first and second rotary magnets 31 and 32 are arranged so that their phases are shifted by an angle θ1 obtained by the following equation (1) with respect to the number m of magnetic poles of the first and second rotary magnets 31 and 32. It has become.

    θ1 = 360 / (2 · m) (1)

  Further, since the first and second rotating magnets 31 and 32 are equally divided into a plurality of magnetic poles (S poles and N poles) in the circumferential direction, an “electrical angle” and a “mechanical angle” used in a resolver or a motor. Can be applied. That is, in the first and second rotating magnets 31 and 32, an angle representing an interval between the same poles as 360 degrees (one cycle) is “electrical angle”, and 1 of the first and second rotating magnets 31 and 32. An angle representing the rotation as 360 degrees (one cycle) can be a “mechanical angle”. When the electrical angle is θd, the mechanical angle is θk, and the number of magnetic poles is m, the following equation (2) is established. Therefore, the mechanical angle θk1 for one electrical angle cycle can be expressed by the following equation (3).

θk = θd / (m / 2) (2)
θk1 = 360 / (m / 2) (3)

  As shown in FIG. 8, the first and second sub-rotating magnets 21 and 22 are also equally divided into predetermined even-numbered n (for example, n = 4) magnetic poles (S pole, N pole) in the circumferential direction. The number of magnetic poles of the first and second sub-rotating magnets 21 and 22 is different from the number of magnetic poles of the first and second rotating magnets 31 and 32. The position of the N magnetic pole of the first sub-rotating magnet 21 and the position of the S magnetic pole of the second sub-rotating magnet 22 are held in agreement with each other regardless of whether or not the torsion bar 14 is twisted. That is, the phases of the first and second sub-rotating magnets 21 and 22 are shifted by an angle θ2 obtained by the following equation (4) with respect to the number n of magnetic poles of the first and second sub-rotating magnets 21 and 22. It is arranged.

    θ2 = 360 / n (4)

  As shown in FIG. 1, a yoke stator 33 is provided inside the support housing 11 at a position surrounding the first and second rotating magnets 31 and 32 from the side, and the first and second sub-rotating magnets. A sub yoke stator 23 is provided at a position surrounding the sides 21 and 22 from the side. As shown in FIG. 2, the yoke stator 33 includes a pair of yoke groups 34, 34 arranged to face each other in the axial direction. Each yoke group 34 includes the first yoke 35, the second yoke 36, and the third yoke 37 shown in FIG. The first magnetic path constituting member 35S corresponding to the “magnetic path constituting member” of the present invention is formed by a pair of first yokes 35, 35 respectively included in one and the other yoke groups 34, 34 (FIG. 2 and FIG. 2). 4A) is configured, and a pair of second yokes 36, 36 included in one and the other yoke group 34, 34, respectively, provide a second corresponding to the “magnetic path constituent member” of the present invention. A magnetic path constituting member 36S (see FIG. 2) is configured, and the pair of third yokes 37 and 37 included in one and the other yoke groups 34 and 34 correspond to the “magnetic path constituting member” of the present invention. A third magnetic path constituent member 37S (see FIG. 2) is configured.

  The first yoke 35 is formed by punching and bending a sheet metal, for example, and includes an annular portion 35A centered on the torsion bar 14, and a plurality (for example, three) of magnetic pole facing portions are provided on the annular portion 35A. 35B and the relay part 35C are integrally formed. The plurality of magnetic pole facing portions 35B are formed by bending a projecting piece extending inward from the annular portion 35A at a right angle in the middle, with an interval corresponding to one cycle of the electrical angle of the first and second rotating magnets 31 and 32. It is arranged at a position where the circumferential direction of the annular portion 35A is divided into a plurality of equal parts (for example, three equal parts). As shown in FIG. 4A, each magnetic pole facing portion 35B of one first yoke 35 is disposed to face the outer peripheral surface of the first rotating magnet 31 with a gap therebetween, and the other first yoke. Each of the 35 magnetic pole facing portions 35 </ b> B is disposed to face the outer peripheral surface of the second rotating magnet 32 in the radial direction of the torsion bar 14 with a gap. Further, between the first yokes 35 and 35, the magnetic pole facing portions 35 </ b> B and 35 </ b> B are opposed to each other in the axial direction of the torsion bar 14.

  The relay portion 35C is disposed at the same position as any of the magnetic pole facing portions 35B in the circumferential direction of the annular portion 35A. The relay portion 35C has a structure in which a projecting piece extending outward from the annular portion 35A is bent at a right angle and its tip is bent at a right angle outward. The relay portions 35C and 35C are opposed to each other between the first yokes 35 and 35 in the axial direction, and the “magnetic path magnetic flux intensity detecting means” of the present invention is between the tip portions of the relay portions 35C and 35C. The Hall element 35H is arranged.

  As shown in FIG. 2, each of the second and third yokes 36 and 37 constituting the second and third magnetic path constituting members 36S and 37S has an annular portion 36A, 37A, magnetic pole facing portions 36B and 37B, and relay portions 36C and 37C are provided. In each yoke group 34, the annular portions 35 </ b> A, 36 </ b> A, 37 </ b> A are stacked with a gap in the axial direction of the torsion bar 14. Here, the first, second, and third yokes 35, 36, and 37 are arranged so as to be shifted by an electrical angle of 1/3 period, and as a result, the magnetic pole facing portions 35B, 36B, and 37B have an electrical angle of 1/3. It arrange | positions in the position which divided the circumference | surroundings of the axis | shaft of the torsion bar 14 into multiple equal intervals at intervals. In addition, the magnetic poles are opposed to each other between the first to third yokes 35, 36, and 37 so that the tips of all the magnetic pole opposed portions 35B, 36B, and 37B are disposed at the same position in the axial direction of the torsion bar 14. The lengths of the portions 35B, 36B, and 37B are different. Furthermore, the tips of all the relay portions 35C, 36C, 37C are also arranged at the same position in the axial direction of the torsion bar 14. Similarly to the Hall element 35H between the relay portions 35C and 35C, Hall elements 36H and 37H are provided between the relay portions 36C and 36C and between the relay portions 37C and 37C, respectively. As shown in FIG. 1, the output lines of the hall elements 35H, 36H, and 37H are connected to terminal fittings 11D that stand from the rear wall of the connector portion 11C formed on the outer surface of the support housing 11. A signal processing circuit 39 (corresponding to a “signal processing unit” according to the present invention) connected to the connector unit 11C processes the outputs of the Hall elements 35H, 36H, and 37H.

  The first to third magnetic path constituting members 35S, 36S, 37S (see FIG. 2) constitute a magnetic path between the first and second rotating magnets 31, 32. Hereinafter, the first magnetic path constituting member 35S will be described in more detail as an example. That is, in a state where the torsion bar 14 is not twisted, for example, as shown in FIG. 4A, each magnetic pole facing portion 35B of the first yoke 35 of the first magnetic path constituting member 35S is The magnetic pole facing portions 35 </ b> B of the other first yoke 35 face the N magnetic pole of the first rotating magnet 31, and can face the S magnetic pole of the second rotating magnet 32. At this time, the magnetic flux from the N magnetic pole of the first rotating magnet 31 is directed from each magnetic pole facing portion 35B of one first yoke 35 to the annular portion 35A and the relay portion 35C, passes through the Hall element 35H, Further, the relay portion 35 </ b> C of the other first yoke 35 goes to the annular portion 35 </ b> A, each magnetic pole facing portion 35 </ b> B, and the S magnetic pole of the second rotating magnet 32. That is, a magnetic path between the first rotating magnet 31 and the second rotating magnet 32 is configured by the first magnetic path constituting member 35S.

  When the first and second rotating magnets 31 and 32 rotate while maintaining the state where the torsion bar 14 is not twisted and deformed from the above state, the strength of the magnetic flux passing through the Hall element 35H gradually decreases, and FIG. As shown in FIG. 6B, each magnetic pole facing portion 35B of one first yoke 35 faces the N magnetic pole of the first rotating magnet 31, and each magnetic pole facing portion 35B of the other first yoke 35 is also second. The strength of the magnetic flux passing through the Hall element 35H becomes “0” in a state of facing the N magnetic pole of the rotating magnet 32.

  When the first and second rotating magnets 31 and 32 further rotate from this state, the strength of the magnetic flux gradually increases after the direction of the magnetic flux passing through the Hall element 35H is reversed. Then, as shown in FIG. 4C, each magnetic pole facing portion 35B of one first yoke 35 faces the S magnetic pole of the first rotating magnet 31, and each magnetic pole facing portion 35B of the other first yoke 35. Until the state of the second rotating magnet 32 faces the N magnetic pole, the strength of the magnetic flux passing through the Hall element 35H increases, and after passing through this state, the strength of the magnetic flux passing through the Hall element 35H decreases. . In this way, the output of the Hall element 35H changes as shown by the SIN curve g1 shown in FIG. 6 as the first and second rotating magnets 31 and 32 rotate. Similarly, the outputs of the Hall elements 36H and 37H in the second and third magnetic path constituting members 36S and 37S also change like the SIN curves g2 and g3 shown in FIG. 6, and these Hall elements 35H and 36H. , 37H output change SIN curves g1, g2, g3 are shifted in phase by 1/3 period of electrical angle, which is a shift between the first to third magnetic path constituting members 35S, 36S, 37S.

  Next, changes in the outputs of the Hall elements 35H, 36H, and 37H when the torsion bar 14 is twisted will be described using the first magnetic path constituting member 35S as an example. In a state where the torsion bar 14 is not twisted and deformed, as shown in FIG. 5B, the boundary portion between the adjacent N magnetic pole and S magnetic pole in the first rotating magnet 31 is N in the second rotating magnet 32. Opposite the centers of the magnetic pole and S magnetic pole. As shown in the figure, when each magnetic pole facing portion 35B of one first yoke 35 faces the center of the N magnetic pole of the first rotating magnet 31, each magnetic pole facing portion 35B of the other first yoke 35 is provided. Faces the boundary portion between the N magnetic pole and the S magnetic pole in the second rotating magnet 32.

  When the torsion bar 14 is twisted to one side from the state shown in FIG. 5B, an N magnetic pole and an S magnetic pole are provided between the first and second rotating magnets 31 and 32 as shown in FIG. The amplitude value of the output change of the Hall element 35H in the SIN curve g1 becomes larger as the state approaches the opposite-polarity opposing state in which the phases of the two elements are matched.

  On the other hand, when the torsion bar 14 is twisted to the other side from the state shown in FIG. 5B, as shown in FIG. 5C, the N magnetic pole is formed between the first and second rotating magnets 31 and 32. The amplitude value in the SIN curve g1 of the output change of the Hall element 35H becomes smaller as approaching the same pole facing state where the phases of the S magnetic poles coincide with each other. That is, when the SIN curve g1 of the output change of the Hall element 35H when the torsion bar 14 is not twisted is indicated by a two-dot chain line in FIG. 7, when the torsion bar 14 is twisted to one side, it is indicated by a broken line in FIG. When the torsion bar 14 is twisted to the other side as shown in the SIN curve g11 and the torsion bar 14 is twisted to the other side, the amplitude value is reduced as shown in the SIN curve g12 shown by the solid line in FIG. Similarly, the amplitude value of the output change of the Hall elements 36H and 37H in the SIN curves g2 and g3 also changes depending on the twist of the torsion bar 14. Then, the signal processing circuit 39 (see FIG. 1) calculates the torque applied to the torsion bar 14 from the amplitude values of the SIN curves g1, g2, and g3, as will be described in detail later.

  This completes the description of the configuration of the yoke stator 33. Next, the configuration of the sub yoke stator 23 will be described. As shown in FIG. 8, similarly to the yoke stator 33, the sub yoke stator 23 includes a pair of sub yoke groups 24, 24 arranged opposite to each other in the axial direction, and one of the sub yoke groups 24 includes the first sub rotating magnet 21. And the other sub-yoke group 24 surrounds the second sub-rotating magnet 22 from the side. Each sub yoke group 24 includes first to third sub yokes 25, 26, and 27. The pair of first sub yokes 25, 25 constitute a first sub magnetic path constituent member 25S corresponding to the “sub magnetic path constituent member” of the present invention (see FIG. 10). 26, 26 constitutes a second sub magnetic path constituting member 26S corresponding to the “sub magnetic path constituting member” of the present invention, and a pair of third sub yokes 27, 27 constitutes a “sub magnetic path configuration of the present invention. A third sub magnetic path constituting member 27 </ b> S corresponding to “member” is constituted.

  As shown in FIG. 9, the first sub-yoke 25 includes an annular portion 25A, a magnetic pole facing portion 25B, and a relay portion 25C, like the first yoke 35 (see FIG. 3). A plurality of magnetic pole facing portions 25B are evenly arranged in the circumferential direction of the annular portion 25A with an interval of one electrical angle between the first and second sub-rotating magnets 21 and 22. The first and second sub-rotating magnets 21 and 22 and the first and second rotating magnets 31 and 32 are different from each other in the number of magnetic poles and one electrical angle cycle. The number of portions 25B and the number of magnetic pole facing portions 35B of the first yoke 35 are also different from each other.

  As shown in FIG. 8, similarly to the first sub yoke 25, the second and third sub yokes 26 and 27 include ring portions 26A and 27A, magnetic pole facing portions 26B and 27B, and relay portions 26C and 27C. Yes. In each sub-yoke group 24, the annular portions 25A, 26A, 27A are overlapped with a gap in the axial direction of the torsion bar 14, and the first to third sub-yokes 25, 26, 27 are first and first The two sub-rotating magnets 21 and 22 are shifted from each other by an electrical angle of 1/3 period, and the magnetic pole facing portions 25B, 26B, and 27B are disposed at positions equally divided around the axis of the torsion bar 14.

  A hall element 25H is provided between the relay portions 25C and 25C of the pair of first sub yokes 25 and 25. Similarly, between the relay portions 26C and 26C of the pair of second sub yokes 26 and 26 and between the relay portions 27C and 27C of the pair of third sub yokes 27 and 27, the Hall elements 26H and 27H are also provided. Are provided. As the first and second sub-rotating magnets 21 and 22 rotate, the output of each of the hall elements 25H, 26H, and 27H is the same as the output of the hall elements 35H, 36H, and 37H as described above. It changes so as to draw a SIN curve whose phase is shifted by period. The output lines of the Hall elements 25H, 26H, and 27H are connected to the terminal fitting 11D that stands up from the back wall of the connector portion 11C of the support housing 11 as shown in FIG. 1, as with the Hall elements 35H, 36H, and 37H described above. It is connected. The signal processing circuit 39 connected to the connector portion 11C processes the outputs of the hall elements 25H, 26H, and 27H.

  The signal processing circuit 39 calculates the torque related to the torsion bar 14 based on the outputs of the Hall elements 35H, 36H, and 37H provided in the yoke stator 33. As described above, when torque is applied to the torsion bar 14, the amplitude values of the SIN curves g1, g2, and g3 of the output changes of the Hall elements 35H, 36H, and 37H change depending on the twisting direction. To do. Here, if the amplitude value is obtained using only the SIN curve g1 related to one Hall element 35H, it is necessary to rotate the first and second rotating magnets 31 and 32 by at least one electrical angle cycle.

  However, in the torque sensor 10 of the present embodiment, the outputs of the three Hall elements 35H, 36H, and 37H are shifted by 1/3 period of electrical angle and change just like a three-phase alternating current (see FIG. 6). ), It is not necessary to rotate the first and second rotating magnets 31 and 32 in order to obtain the amplitude value. That is, assuming that the output of the Hall element 35H is V1, the output of the Hall element 36H is V2, and the output of the Hall element 37H is V3, the amplitude values S of the SIN curves g1, g2, and g3 related to the Hall elements 35H, 36H, and 37H (FIG. 6) can be obtained by the following equation (5). Then, the signal processing circuit 39 repeatedly executes a torque calculation program (not shown) for obtaining the torque of the torsion bar 14 at a predetermined cycle using the equation (5) to calculate the amplitude value S. Then, the torque is obtained based on the magnitude relationship between the amplitude value S and a predetermined reference value.

・・・・・（５）

(5)

  Further, the signal processing circuit 39 includes outputs of Hall elements 35H, 36H, and 37H provided in the yoke stator 33 (see FIG. 2) and Hall elements 25H, 26H, and 27H provided in the sub-yoke stator 23 (see FIG. 8). More specifically, the rotational position of the torsion bar 14 is calculated based on the output. Specifically, when the torsion bar 14 rotates, the outputs of the Hall elements 35H, 36H, and 37H are set to the SIN curves g1, g2, and g3 as described above. Draw and change. Here, when the current position at the electrical angle is obtained using only the SIN curve g1 of the output change of one Hall element 35H, there are two solutions for the current position.

  However, in the torque sensor 10 of the present embodiment, the outputs of the three Hall elements 35H, 36H, and 37H in the yoke stator 33 are shifted by an electrical angle of 1/3 period, just like a three-phase AC. Therefore, the solution of the current position of the electrical angle of the torsion bar 14 can be uniquely specified using the outputs of the Hall elements 35H, 36H, and 37H. Similarly, in the sub-yoke stator 23, the outputs of the three Hall elements 25H, 26H, and 27H are shifted by an electrical angle of 1/3 period and are just like three-phase alternating current. The solution of the current position of the electrical angle of the torsion bar 14 can be uniquely specified using the outputs of 25H, 26H, and 27H.

  The number of magnetic poles m (for example, m = 6) of the first and second rotating magnets 31 and 32 rotating inside the yoke stator 33 and the first and second sub-rotations rotating inside the sub-yoke stator 23. Since the number of magnetic poles n (for example, n = 4) of the magnets 21 and 22 is different, the current position of the electrical angle obtained from the Hall elements 35H, 36H, and 37H of the yoke stator 33 and the Hall element of the sub-yoke stator 23 The mechanical angle of the torsion bar 14 can be uniquely specified from the combination of the electrical angle obtained from 25H, 26H, and 27H with the current position.

  Specifically, as shown in the graph of FIG. 11, the first electrical angle obtained from the Hall elements 35H, 36H, and 37H of the yoke stator 33 at a mechanical angle of 360 degrees of the torsion bar 14 is, for example, 3 cycles. On the other hand, the second electrical angle obtained from the Hall elements 25H, 26H, and 27H of the sub yoke stator 23 is repeatedly changed over, for example, two periods. As a result, the first electrical angle and the second electrical angle corresponding to the mechanical angle of the torsion bar 14 are determined one by one, and the mechanical angle of the torsion bar 14 is determined by the combination of the first and second electrical angles. It is uniquely identified. The signal processing circuit 39 stores a data table corresponding to the graph shown in FIG. Then, the signal processing circuit 39 repeatedly executes a rotational position calculation program (not shown) at a predetermined cycle, the current position of the electrical angle obtained from the Hall elements 35H, 36H, and 37H of the yoke stator 33, and the sub-yoke stator. The mechanical angle of the torsion bar 14 is obtained based on the current position of the electrical angle obtained from the 23 Hall elements 25H, 26H, and 27H and the data table.

  This completes the description of the configuration of the present embodiment. According to the torque sensor 10 of the present embodiment configured as described above, the following operational effects can be obtained. That is, in the torque sensor 10 of the present embodiment, the first to third magnetic path constituting members 35S, 36S, 37S constituting the magnetic path between the first and second rotating magnets 31, 32 and the magnetic flux passing through them. Hall elements 35H, 36H, and 37H for detecting the strength of each of these are fixed to the support housing 11, so that the problem of gap variation and the decrease of magnetic flux strength as in the conventional torque sensor are solved. Torque can be detected accurately.

  Further, since each of the first to third magnetic path constituting members 35S, 36S, and 37S includes a plurality (three) of magnetic pole facing portions 35B, 36B, and 37B, the magnetic pole facing portions 35B, 36B, and 37B are provided. And the first and second rotary magnets 31 and 32 can be secured with a wide area. Thus, a large amount of magnetic flux from the first and second rotating magnets 31 and 32 can be taken into the magnetic path constituting members 35S, 36S, and 37S. The magnetic flux is collected in the relay portions 35C, 36C, and 37C of the magnetic path constituting members 35S, 36S, and 37S and is passed through the Hall elements 35H, 36H, and 37H, so that the magnetic flux intensity detection accuracy is improved and the torque detection accuracy is improved. Will also improve.

  Furthermore, in the torque sensor 10 of the present embodiment, the first to third magnetic path constituting members 35S, 36S, and 37S are arranged with the phase of the electrical angle 1/3 period shifted, so that the torsion bar 14 is not rotated. Even so, the torque can be detected using the detection results of the three Hall elements 35H, 36H, and 37H and the above equation (5).

  In addition, the torque sensor 10 of the present embodiment includes first and second sub-rotating magnets 21 and 22 in addition to the first and second rotating magnets 31 and 32 for detecting torque. Thus, the mechanical angle of the torsion bar 14 can be obtained. At this time, since the configurations of the first and second rotating magnets 31 and 32 for detecting the torque are used for detecting the mechanical angle of the torsion bar 14, both functions of torque detection and position detection are used. The entire torque sensor 10 provided can be reduced in size.

[Second Embodiment]
In the present embodiment shown in FIG. 12, the torque sensor 10 of the first embodiment is used as a part of the electric power steering device 50. Specifically, the electric power steering apparatus 50 includes a shaft 52 between steered wheels passed between a pair of steered wheels 51, 51 and a shaft case 53 covering the outside of the shaft 52 between steered wheels. I have. A hollow motor 54 is provided at an intermediate portion in the axial direction of the shaft case 53, and the inter-steering wheel shaft 52 passes through a cylindrical rotor 54 </ b> R provided in the hollow motor 54. Further, a ball nut 55N is fitted and fixed inside the rotor 54R, and the ball nut 55N is screwed into a ball screw portion 55J formed at an intermediate portion in the axial direction of the inter-steering wheel shaft 52 to constitute a ball screw mechanism 55. Has been.

  Further, a rack 56 is formed at one end of the inter-steering wheel shaft 52. On the other hand, a sensor fixing cylinder portion 57 is provided at one end portion of the shaft case 53. Then, a pinion 16G provided at one end of the torque sensor 10 is inserted into the upper end opening of the sensor fixing cylinder 57 and meshes with the rack 56, and the support housing 11 of the torque sensor 10 is fixed to the sensor fixing cylinder 57. Yes.

  A steering shaft 61 extending downward from the handle 60 is splined to the spline portion 15S (see FIG. 1) on the opposite side of the torque sensor 10 from the pinion 16G. The connector portion 11C (see FIG. 1) of the torque sensor 10 is connected to the steering control device 63 including the signal processing circuit 39 described above. A vehicle speed sensor 62 is also connected to the steering control device 63. The steering control device 63 controls the hollow motor 54 based on the detection results of the torque sensor 10 and the vehicle speed sensor 62 so that the steering resistance is relatively small when the vehicle is traveling at a low speed and the steering resistance is relatively large when the vehicle is traveling at a high speed. Control.

  As described above, the electric power steering apparatus 50 according to the present embodiment is provided with the torque sensor 10 capable of detecting the torque more accurately than the conventional one for detecting the steering resistance of the handle 60 as described above. The output of the power steering device 50 (that is, (the output torque of the hollow motor 54) can be controlled.

[Other Embodiments]
The present invention is not limited to the above-described embodiment. For example, the embodiments described below are also included in the technical scope of the present invention, and various other than the following can be made without departing from the scope of the invention. It can be changed and implemented.

(1) The torque sensor 10 of the above embodiment is configured to be able to detect both the torque and the position relating to the torsion bar 14, but excludes the first and second sub-rotating magnets 21, 22, etc. Thus, the configuration may be such that only the torque can be detected.

(2) Although the torque sensor 10 of the above embodiment includes the three magnetic path constituent members 35S, 36S, and 37S, the torque sensor 10 may include only one magnetic path constituent member 35S. In this case, the torque may be detected by rotating the torsion bar 14 by one electrical angle cycle.

1 is a side sectional view of a torque sensor according to a first embodiment of the present invention. Perspective view of rotating magnet and magnetic path constituent member provided in torque sensor A perspective view of the first rotating magnet and the first to third yokes Perspective view of first and second rotating magnets and first yoke Side view of first and second rotating magnets and first yoke Graph showing Hall element output Graph showing the output of the Hall element that changes according to the twist of the torsion bar Perspective view of sub rotary magnet and sub magnetic path constituting member provided in torque sensor A perspective view of the first sub-rotating magnet and the first to third sub-yokes A perspective view of the first and second sub-rotating magnets and the first sub-yoke A graph showing the relationship between two types of electrical angles and mechanical angles Side sectional view of electric power steering device Side sectional view of a conventional torque sensor Exploded perspective view of a conventional torque sensor Side view of a conventional torque sensor

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Torque sensor 11 Support housing 21 1st sub rotary magnet 22 2nd sub rotary magnet 25A, 26A, 27A Ring part 25B, 26B, 27B Magnetic pole opposing part 25C, 26C, 27C Relay part 25H, 26H, 27H Hall element (Magnetic flux detection means)
25S, 26S, 27S Sub magnetic path constituting member 26, 26 Second sub yoke 26, 27 Sub yoke 31 First rotating magnet 32 Second rotating magnet 35A, 36A, 37A Annular portion 35B, 36B, 37B Magnetic pole facing portion 35C, 36C, 37C Relay section 35H, 36H, 37H Hall element (magnetic flux intensity detection means)
35S, 36S, 37S First to third magnetic path constituent members 39 Signal processing circuit (signal processing unit)
50 Electric power steering device 60 Handle

Claims (8)

In a torque sensor for detecting torque based on torsion of a torsion bar rotatably supported by a support housing,
A first rotating magnet having a circular shape centered on the torsion bar, equally divided into a plurality of magnetic poles in the circumferential direction, and rotating integrally with one end of the torsion bar;
A second rotating magnet having a circular shape around the torsion bar, equally divided in the circumferential direction into the same number of magnetic poles as the first rotating magnet, and rotating integrally with the other end of the torsion bar;
A magnetic path constituting member fixed to the support housing and constituting a magnetic path between the first and second rotating magnets;
A first magnetic pole facing portion formed on the magnetic path constituting member and capable of facing the magnetic poles of the first rotating magnet according to the rotational position of the first rotating magnet;
A second magnetic pole facing portion formed on the magnetic path constituting member and capable of facing the magnetic poles of the second rotating magnet according to the rotational position of the second rotating magnet;
A torque sensor comprising: magnetic flux intensity detecting means for detecting the intensity of magnetic flux passing through the magnetic path constituting member. The magnetic path component member is provided with a pair of annular portions centered on the torsion bar,
A plurality of the first magnetic pole facing portions are arranged at a plurality of positions along the circumferential direction of one of the annular portions at intervals of an integral multiple of one electrical angle of the first rotating magnet,
A plurality of the second magnetic pole facing portions are arranged at a plurality of positions along the circumferential direction of the other annular portion at intervals of an integral multiple of one cycle of the electrical angle of the second rotating magnet. The torque sensor according to claim 1.   Three magnetic path constituent members are provided by shifting the phase of the first rotating magnet by an electrical angle of 1/3 period, and the detection results of the three magnetic flux intensity detecting means respectively provided in the three magnetic path constituent members The torque sensor according to claim 1, wherein the torque sensor can be output. When the detection results of the three magnetic flux intensity detection means are V1, V2, and V3,

4. The torque according to claim 3, further comprising a signal processing unit that calculates a calculated value S and calculates the torque based on a magnitude relationship between the calculated value S and a predetermined reference value. 5. Sensor.   The first and second magnetic pole opposing portions are arranged in the same phase around the torsion bar, and the first and second rotary magnets are moved by an electrical angle of 1/4 period in a state where the torsion bar is not twisted. The torque sensor according to any one of claims 1 to 4, wherein the torque sensor is arranged so as to be shifted by a distance.   A plurality of magnetic path constituent members are provided, and a plurality of SIN curves having a phase difference are drawn when detection results of the magnetic flux intensity detecting means provided for each of the plurality of magnetic path constituent members rotate the torsion bar. 6. The plurality of magnetic path constituting members are arranged so as to change, and the electrical angle of the torsion bar can be detected from the detection results of the plurality of magnetic flux intensity detecting means. The torque sensor according to any one of the above. A sub-rotary magnet that is circularly shaped around the torsion bar, equally divided in a circumferential direction into a plurality of magnetic poles different from the number of magnetic poles of the first and second rotary magnets, and rotates integrally with the torsion bar;
A plurality of sub magnetic path constituent members fixed to the support housing and capable of facing the magnetic poles of the sub rotary magnet according to the rotational position of the sub rotary magnet;
A plurality of sub magnetic flux intensity detecting means for detecting magnetic flux intensity of the sub rotating magnet passing through the plurality of sub magnetic path constituting members;
The plurality of sub magnetic path constituting members are arranged so that the detection results of the plurality of sub magnetic flux intensity detecting means change while drawing a plurality of SIN curves having a phase difference when the torsion bar is rotated. , The electrical angle of the torsion bar can be detected from the detection results of the plurality of sub magnetic flux intensity detection means,
Based on the combination of the electrical angle of the torsion bar detected by the calculation result of the plurality of sub-magnetic flux intensity detection means and the electrical angle of the torsion bar detected by the calculation result of the plurality of magnetic flux intensity detection means The torque sensor according to claim 6, wherein the mechanical angle of the torsion bar can be calculated.   An electric power steering apparatus comprising the torque sensor according to any one of claims 1 to 7 for detecting steering resistance of a steering wheel.

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