Magnetostrictive torque sensor

Abstract

To provide a magnetostrictive torque sensor that can be miniaturized.SOLUTION: A magnetostrictive torque sensor 1 that is mounted around a rotating shaft 9 having a magnetostrictive effect and detects torque transmitted by the rotating shaft 9 includes: a holder 2 having a cylindrical section 21 in which a cavity 20 into which the rotating shaft 9 is inserted is formed in the center and a projection 22 that projects to the radial outside from the cylindrical section 21 and is provided; and a flexible board 4 having a detection section 40 in which coil groups 4A to 4D in which multiple detection coils lined up in a predetermined direction are combined are formed by wiring patterns, and a signal line section 400 in which multiple signals lines 491 to 494 for electrically connecting the coil groups and an external device 6 are formed by wiring patterns. The detection section 40 is wound around the outer periphery of the cylindrical section 21 of the holder 2, one portion in the longitudinal direction of the signal line section 400 is fixed to the projection 22 of the holder 2 by an adhesive 7 or a pressure-sensitive adhesive tape 8, and a tip side of the fixed section is guided to the outside of the holder 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a magnetostrictive torque sensor that detects torque transmitted by a rotating shaft having a magnetostrictive effect.

Background Art

[0002] Conventionally, for example, a magnetostrictive torque sensor has been used to detect torque such as the output rotating shaft of an automobile engine. The magnetostrictive torque sensor utilizes the magnetostrictive effect in which the magnetic permeability of a rotating shaft changes due to stress, and is configured to detect the torque applied to the rotating shaft based on a change in the inductance of a detection coil disposed around the rotating shaft. The present applicant has proposed a magnetostrictive torque sensor in which a flexible substrate formed with a plurality of detection coils is disposed around a rotating shaft, and the torque applied to the rotating shaft is detected based on changes in the inductances of the plurality of detection coils (see Patent Document 1).

[0003] The magnetostrictive torque sensor described in Patent Document 1 houses a flexible substrate formed with a plurality of detection coils in a resin housing. A plurality of terminal portions are provided at the ends of the flexible substrate, and signal lines of a cable are connected to these terminal portions within the resin housing. The cable is led out from the resin housing and connected to a control device.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] There are cases where it is difficult to secure space for installing a torque sensor around a rotating shaft, and downsizing of the torque sensor is required. The present invention has been made to meet this requirement, and an object thereof is to provide a magnetostrictive torque sensor that can be downsized.

Means for Solving the Problems

[0006] The present invention is a magnetostrictive torque sensor attached around a rotating shaft having a magnetostrictive effect and detecting torque transmitted by the rotating shaft, comprising: a cylindrical portion having a cavity through which the rotating shaft is inserted formed at a central portion; a holder having a protrusion provided to protrude radially outward from the cylindrical portion; a detection portion in which a coil group formed by combining a plurality of detection coils arranged in a predetermined direction is formed by a wiring pattern; and a flexible substrate having a signal line portion in which a plurality of signal lines electrically connecting the coil group and an external device are formed by a wiring pattern. The detection portion is wound around an outer periphery of the cylindrical portion of the holder, the signal line portion has a part in a longitudinal direction fixed to the protrusion of the holder by a fixing member, and a tip side from the fixed portion is led out to the outside of the holder. The present invention provides a magnetostrictive torque sensor.

Effects of the Invention

[0007] According to the present invention, the magnetostrictive torque sensor can be downsized, and space saving of the installation space becomes possible.

Brief Description of the Drawings

[0008]

Figure 1

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Figure 17

Best Mode for Carrying Out the Invention

[0009] [First Embodiment] FIG. 1 is a perspective view showing the magnetostrictive torque sensor 1 according to the first embodiment of the present invention together with the rotating shaft 9 to be detected. FIG. 2 is an exploded perspective view of the magnetostrictive torque sensor 1. FIG. 3 is an exploded perspective view of the magnetostrictive torque sensor 1 viewed from a direction different from that of FIG. 2. FIG. 4 is a cross-sectional view of the magnetostrictive torque sensor 1.

[0010] The magnetostrictive torque sensor 1 is attached around the rotating shaft 9 and detects the torque transmitted by the rotating shaft 9. The rotating shaft 9 is, for example, a shaft that transmits the driving force of a driving source such as an automobile engine or an electric motor. The detection result of the torque obtained by the magnetostrictive torque sensor 1 is used for control of a driving source, an automatic transmission, or the like.

[0011] The rotating shaft 9 is a ferromagnetic material having a magnetostrictive effect and rotates about the rotation axis O to transmit torque. Here, the magnetostrictive effect is a phenomenon in which when a magnetic field is applied to a ferromagnetic material to magnetize it, strain (deformation) appears in the shape. Then, by using this phenomenon in reverse and detecting the change in magnetic characteristics generated by the strain of the shape, the torque applied to the rotating shaft 9 can be detected. As the rotating shaft 9, for example, a shaft-shaped body made of chromium-containing chromium steel such as chromium steel, chromium molybdenum steel, or nickel chromium molybdenum steel is subjected to carburizing quenching and tempering treatments, and further shot peening can be preferably used.

[0012] The magnetostrictive torque sensor 1 includes a holder 2, a cover member 3, a flexible substrate 4, a magnetic ring 5 made of a soft magnetic material, and an external device 6 disposed outside the holder 2. The external device 6 includes an oscillator 61 and a voltmeter 62 and is electrically connected to the flexible substrate 4. The operation of the external device 6 will be described later.

[0013] The holder 2 is made of a resin material such as PPS (polyphenylene sulfide) and is formed by injection molding. The holder 2 integrally includes a cylindrical portion 21 having a cavity 20 through which the rotation shaft 9 is inserted formed at the center, a protrusion 22 provided to protrude radially outward from the cylindrical portion 21, and a magnetic ring holding portion 23 that holds the magnetic ring 5 between the cylindrical portion 21. The protrusion 22 protrudes in a direction perpendicular to the outer peripheral surface 21a of the cylindrical portion 21 from a part of the circumferential direction of the cylindrical portion 21. The magnetic ring holding portion 23 has a peripheral wall portion 231 facing the end face 5a on one axial side of the magnetic ring 5 and an edge wall portion 232 facing the outer peripheral surface 5b of the end portion on one axial side of the magnetic ring 5. The edge wall portion 232 is formed in an arc shape except for the portion where the protrusion 22 is provided.

[0014] An annular groove 230 for accommodating the end portion on one axial side of the magnetic ring 5 is formed between the inner peripheral surface 232a of the edge wall portion 232 and the outer peripheral surface 21a of the cylindrical portion 21. A recess 220 for accommodating a part of the flexible substrate 4 is formed in the protrusion 22. The holder 2 is arranged such that the central axis C of the cylindrical portion 21 coincides with the rotation axis O of the rotation shaft 9. Hereinafter, the direction parallel to the central axis C of the cylindrical portion 21 is referred to as the axial direction. The annular groove 230 and the recess 220 are formed to be recessed in the axial direction.

[0015] The cover member 3 is made of a resin material similar to that of the holder 2, for example, and is formed by injection molding. The cover member 3 integrally includes a plate portion 31 that covers the one axial side of the recess 220 formed in the protrusion 22 and a boss portion 32 that fits into the recess 220. Details of the shapes of the cover member 3 and the recess 220 will be described later.

[0016] The magnetic ring 5 is made of, for example, steel material or sintered magnetic material, has soft magnetism, and is formed in a cylindrical shape with an inner diameter larger than the outer diameter of the cylindrical portion 21 of the holder 2. When the magnetic ring 5 is made of steel material, a magnetic steel material such as electromagnetic stainless steel can be preferably used, and as its forming method, for example, deep drawing can be used. Further, a long pipe-shaped steel material may be cut out to a predetermined length to form the magnetic ring 5. The magnetic ring 5 is fixed to the holder 2 by, for example, adhesion. Further, the magnetic ring 5 is arranged in the axial direction with the cover member 3, and restricts the movement of the cover member 3 in the direction in which the boss portion 32 detaches from the concave portion 220 of the holder 2.

[0017] In the present embodiment, the magnetic ring 5 integrally has a large-diameter portion 51 and a small-diameter portion 52 with different outer diameters. The inner diameters of the large-diameter portion 51 and the small-diameter portion 52 are the same. The large-diameter portion 51 is provided at one end of the magnetic ring 5 in the axial direction and is housed in the annular groove 230 of the holder 2. The magnetic ring 5 is positioned with respect to the holder 2 by inlay fitting the large-diameter portion 51 into the annular groove 230. More specifically, the relative position between the magnetic ring 5 and the holder 2 in the radial direction perpendicular to the axial direction is determined by the outer peripheral surface 5b of the magnetic ring 5 in the large-diameter portion 51 contacting the inner peripheral surface 232a of the edge wall portion 232.

[0018] As shown in FIG. 3, a notch 510 that is recessed in the axial direction from the end face 5a is formed in a portion of the end face 5a on one side in the axial direction of the magnetic ring 5 that faces the plate portion 31 of the cover member 3. When the cover member 3 and the magnetic ring 5 are assembled to the holder 2, a part of the plate portion 31 of the cover member 3 is housed in the notch 510, and the end face 5a on one side in the axial direction of the magnetic ring 5 abuts against the peripheral wall portion 231 of the magnetic ring holding portion 23 of the holder 2.

[0019] FIG. 5(a) is a plan view showing a single flexible substrate 4. FIG. 5(b) is a plan view showing a base material 4M for multi-sided cutting of a plurality of flexible substrates 4. By cutting out the flexible substrates 4 from the base material 4M, a plurality of flexible substrates 4 can be obtained from a single base material 4M.

[0020] The flexible substrate 4 integrally includes a detection unit 40 having a plurality of detection coils for detecting the magnetic field of the rotation axis 9, and a signal line path unit 400 in which a plurality of signal lines for electrically connecting the external device 6 and the detection unit 40 are formed by a wiring pattern. In FIG. 5, illustration of the plurality of detection coils and the plurality of signal lines is omitted. The flexible substrate 4 is held by the holder 2 with the detection unit 40 wound around the outer periphery of the cylindrical portion 21 of the holder 2, and a part of the signal line path unit 400 is led out to the outside of the holder 2. In the detection unit 40, a coil group formed by combining a plurality of detection coils arranged in a predetermined direction is formed by a wiring pattern. The detection unit 40 has a rectangular shape in which the arrangement direction of the plurality of detection coils is the long side direction.

[0021] A part of the longitudinal direction of the signal line path unit 400 is fixed to the protrusion 22 of the holder 2 by a fixing member described later, and the tip side of the signal line path unit 400 from the portion fixed to the protrusion 22 of the holder 2 is led out to the outside of the holder 2. In the present embodiment, the signal line path unit 400 has a protruding piece portion 401 protruding from the detection unit 40 in a direction perpendicular to the long side direction, and a linear portion 402 extending from the protruding piece portion 401 in the long side direction of the detection unit 40. Due to the shape of the flexible substrate 4, as shown in FIG. 5(b), it is possible to reduce the unnecessary area of the base material 4M and cut out a plurality of flexible substrates 4, thereby improving the yield. The length of the linear portion 402 is, for example, 50 mm or more and 100 mm or less.

[0022] The tab portion 401 protrudes from the central portion in the long side direction of the detection portion 40 in a direction perpendicular to the long side direction of the detection portion 40. A part of the linear portion 402, excluding the base end portion which is the end portion near the tab portion 401 among both end portions in the longitudinal direction and including the tip end portion which is the end portion on the side opposite to the base end portion, is led out to the outside of the holder 2. In the recess 220 of the holder 2, the tab portion 401 and a part of the linear portion 402 are accommodated. At the tip end portion of the linear portion 402, as enlarged and shown in FIG. 1, the first to fourth electrodes 402a to 402d are formed. The linear portion 402 of the flexible substrate 4 may be directly connected to the external device 6 or may be connected to the external device 6 via a cable having a plurality of electric wires. Next, with reference to FIGS. 6 to 8, an example of the configuration of the detection portion 40 will be described in detail.

[0023] FIG. 6 is a cross-sectional view showing the layer structure of the flexible substrate 4. The flexible substrate 4 has a multilayer structure having the first to fourth wiring layers 41 to 44, and in order from one surface 4a corresponding to the outer side of the curvature when wound around the outer periphery of the cylindrical portion 21 to the other surface 4b corresponding to the inner side of the curvature, a coverlay film 451, an adhesive layer 461, the first wiring layer 41, the first base film 471, the second wiring layer 42, an adhesive layer 462, a coverlay film 452, a double-sided tape 48, a coverlay film 453, an adhesive layer 463, the third wiring layer 43, the second base film 472, the fourth wiring layer 44, an adhesive layer 464, and a coverlay film 454 are laminated.

[0024] The first wiring layer 41 and the second wiring layer 42 are wiring patterns formed by etching copper foil, and are respectively formed on the front surface 471a and the back surface 471b of the first base film 471. Similarly, the third wiring layer 43 and the fourth wiring layer 44 are wiring patterns formed by etching copper foil, and are respectively formed on the front surface 472a and the back surface 472b of the second base film 472. The coverlay films 451, 452, 453, 454 are protective films attached to the first to fourth wiring layers 41 to 44 by the adhesive layers 461, 462, 463, 464. The first and second base films 471, 472, and the coverlay films 451, 452, 453, 454 are made of an insulating resin such as polyimide.

[0025] Fig. 7(a) is a plan view showing the wiring pattern of the first wiring layer 41 formed on the front surface 471a of the first base film 471. Fig. 7(b) is a plan view showing the wiring pattern of the second wiring layer 42 viewed from the front surface 471a side of the first base film 471. Fig. 7(c) is a plan view showing the wiring pattern of the third wiring layer 43 formed on the front surface 472a of the second base film 472. Fig. 7(d) is a plan view showing the wiring pattern of the fourth wiring layer 44 viewed from the front surface 472a side of the second base film 472.

[0026] In the first wiring layer 41, the first to tenth detection coils 410 to 419 arranged in the long side direction of the detection unit 40 are formed by the wiring pattern. The first and tenth detection coils 410, 419 are triangular, and the second to ninth detection coils 411 to 418 are parallelogram-shaped. Similarly, in the second wiring layer 42, the first to tenth detection coils 420 to 429 arranged in the long side direction of the detection unit 40 are formed by the wiring pattern. The first and tenth detection coils 420, 429 are triangular, and the second to eighth detection coils 421 to 428 are parallelogram-shaped.

[0027] In the third wiring layer 43, first to tenth detection coils 430 to 439 arranged in the long side direction of the detection unit 40 are formed by wiring patterns. The first and tenth detection coils 430 and 439 are triangular, and the second to ninth detection coils 431 to 438 are parallelogram-shaped. Similarly, in the fourth wiring layer 44, first to tenth detection coils 440 to 449 arranged in the long side direction of the detection unit 40 are formed by wiring patterns. The first and tenth detection coils 440 and 449 are triangular, and the second to ninth detection coils 441 to 448 are parallelogram-shaped.

[0028] The first to tenth detection coils 410 to 419 of the first wiring layer 41 and the first to tenth detection coils 440 to 449 of the fourth wiring layer 44 each have straight portions 410a to 419a, 440a to 449a inclined at a predetermined angle (+45°) to one side with respect to the short side direction of the detection unit 40. The first to tenth detection coils 420 to 429 of the second wiring layer 42 and the first to tenth detection coils 430 to 439 of the third wiring layer 43 each have straight portions 420a to 429a, 430a to 439a inclined at a predetermined angle (-45°) to the other side with respect to the short side direction of the detection unit 40.

[0029] FIG. 8 is a circuit diagram schematically showing a configuration example of an electric circuit constituted by a flexible substrate 4, an oscillator 61, and a voltmeter 62. The first to tenth detection coils 410 to 419 of the first wiring layer 41 are connected in series to form a first coil group 4A, and the first to tenth detection coils 420 to 429 of the second wiring layer 42 are connected in series to form a second coil group 4B. Also, the first to tenth detection coils 430 to 439 of the third wiring layer 43 are connected in series to form a third coil group 4C, and the first to tenth detection coils 440 to 449 of the fourth wiring layer 44 are connected in series to form a fourth coil group 4D.

[0030] The first coil group 4A and the third coil group 4C, and the second coil group 4B and the fourth coil group 4D are respectively connected in series between the first electrode 402a and the second electrode 402b. One end of each of the first coil group 4A and the second coil group 4B and the first electrode 402a are connected by the first signal line 491. One end of each of the third coil group 4C and the fourth coil group 4D and the second electrode 402b are connected by the second signal line 492.

[0031] A third signal line 493 that serially connects the other end of the first coil group 4A and the other end of the third coil group 4C is connected to the third electrode 402c. A fourth signal line 494 that serially connects the other end of the second coil group 4B and the other end of the fourth coil group 4D is connected to the fourth electrode 402d. The first to fourth signal lines 491 to 494 are formed by wiring patterns in the signal line portion 400. The oscillator 61 applies an alternating voltage between the first electrode 402a and the second electrode 402b. The voltmeter 62 measures the voltage between the third electrode 402c and the fourth electrode 402d.

[0032] When torque is applied to the rotation axis 9, the magnetic permeability in the direction +45 degrees with respect to the axial direction decreases (or increases), and the magnetic permeability in the direction -45 degrees with respect to the axial direction increases (or decreases). Therefore, when torque is applied to the rotation axis 9 with an alternating voltage applied from the oscillator 61, the inductance of the first coil group 4A and the fourth coil group 4D decreases (or increases), and the inductance increases (or decreases) in the second coil group 4B and the third coil group 4C. As a result, since the voltage measured by the voltmeter 62 changes, the torque applied to the rotation axis 9 can be detected based on this change in voltage.

[0033] In FIGS. 7(a) to 7(d), illustration of the wiring patterns of the portions connecting the first to tenth detection coils 410 to 419, 420 to 429, 430 to 439, 440 to 449 of the first to fourth wiring layers 41 to 44 in series and the wiring patterns of the first to fourth signal lines 491 to 494 are omitted.

[0034] On the other hand, the other surface 4b of the detection unit 40 is adhered to the outer peripheral surface 21a of the cylindrical portion 21 of the holder 2 by an adhesive. Note that both ends in the long side direction of the detection unit 40 may be fixed to the outer peripheral surface 21a of the cylindrical portion 21 by, for example, an adhesive tape. The magnetic ring 5 is disposed so as to surround the outer periphery of the detection unit 40 facing one surface 4a of the flexible substrate 4. The magnetic ring 5 increases the magnetic flux interlinking with each of the detection coils 410 to 419, 420 to 429, 430 to 439, and 440 to 449, and enhances the sensitivity of the magnetostrictive torque sensor 1. A space is formed between one surface 4a of the detection unit 40 and the inner peripheral surface 5c of the magnetic ring 5 so that the flexible substrate 4 and the magnetic ring 5 do not come into contact with each other.

[0035] Next, the protrusion 22 of the holder 2 and the surrounding configuration will be described with reference to FIGS. 9 to 14. In the present embodiment, a part of the linear portion 402 in the longitudinal direction of the signal line portion 400 of the flexible substrate 4 is fixed to the protrusion 22 of the holder 2 by an adhesive 7 as a fixing member. FIGS. 9(a) and (b) are perspective views of the holder 2 and the cover member 3 viewed from different angles. FIGS. 10(a) to (c) are perspective views of the cover member 3. FIG. 11(a) is a configuration diagram showing the periphery of the protrusion 22 of the holder 2 together with a part of the cover member 3 and the flexible substrate 4. FIG. 11(b) is a configuration diagram showing the periphery of the protrusion 22 of the holder 2 and a part of the flexible substrate 4 in a state where the cover member 3 is not combined. FIG. 12(a) is a cross-sectional view of the holder 2, the cover member 3, the flexible substrate 4, and the adhesive 7 taken along line A-A in FIG. 11(a). FIG. 12(b) is an enlarged view of part B in FIG. 12(a). FIG. 13(a) is a cross-sectional view of the holder 2, the cover member 3, the flexible substrate 4, and the adhesive 7 in a cross-section perpendicular to the axial direction. FIG. 13(b) is an enlarged view of part C in FIG. 13(a). FIG. 14 is a partially enlarged view of a part of the holder 2, the cover member 3, the flexible substrate 4, and the adhesive 7 viewed from the direction of arrow D in FIG. 11(a).

[0036] The protruding portion 22 has a pair of side wall portions 221 and 222 arranged in the circumferential direction of the cylindrical portion 21 with the concave portion 220 therebetween, and a bottom wall portion 223 forming the bottom surface 220c of the concave portion 220. The pair of side wall portions 221 and 222 are provided so as to protrude axially from the bottom wall portion 223 and form the inner wall surfaces 220a and 220b of the concave portion 220. Hereinafter, one of the pair of side wall portions 221 and 222, i.e., the side wall portion 221, is referred to as the first side wall portion 221, and the other side wall portion 222 is referred to as the second side wall portion 222. Also, among the inner wall surfaces 220a and 220b, the inner wall surface 220a of the first side wall portion 221 is referred to as the first inner wall surface 220a, and the inner wall surface 220b of the second side wall portion 222 is referred to as the second inner wall surface 220b. The first inner wall surface 220a and the second inner wall surface 220b face each other in parallel with the concave portion 220 therebetween.

[0037] The linear portion 402 of the signal line portion 400 in the flexible substrate 4 is bent inside the concave portion 220 and led out to the outside of the holder 2 so as to extend in a direction perpendicular to the arrangement direction of the first side wall portion 221 and the second side wall portion 222. The linear portion 402 is bent at a substantially right angle near the end on the cylindrical portion 21 side in the concave portion 220. In FIGS. 11(a) and (b), the bent portion where the linear portion 402 is bent is indicated by reference numeral 400a. The linear portion 402 extends along the arrangement direction of the first side wall portion 221 and the second side wall portion 222 in the portion closer to the protruding piece portion 401 than the bent portion 400a, and extends along the first inner wall surface 220a in the portion on the tip side of the bent portion 400a.

[0038] A part of the linear portion 402 on the tip side of the bent portion 400a is fixed by the adhesive 7 so as to face the first inner wall surface 220a of the concave portion 220. The first inner wall surface 220a is parallel to the leading direction of the linear portion 402 from the holder 2. Here, the leading direction of the linear portion 402 refers to the extending direction of the portion on the tip side of the bent portion 400a when the portion is linear across the inside and outside of the concave portion 220.

[0039] As shown in FIGS. 10(a) to (c), the cover member 3 integrally has a flat plate portion 31 and a boss portion 32 which is a projection protruding in a direction perpendicular to the plate portion 31. The plate portion 31 has a rectangular shape when viewed from the axial direction. A holding portion 320 for holding the adhesive 7 is formed in the boss portion 32, and an engaging portion 321 that engages with an engaged portion 222a provided on the second side wall portion 222 is provided.

[0040] In the present embodiment, the engaged portion 222a is a recess provided so as to be recessed from the second inner wall surface 220b. The engaging portion 321 is a projection protruding toward the second side wall portion 222 side rather than the plate portion 31 in the axial view. By engaging the engaging portion 321 of the cover member 3 with the engaged portion 222a of the protrusion 22 of the holder 2, the position of the cover member 3 with respect to the holder 2 in the radial direction of the cylindrical portion 21 is defined.

[0041] In FIG. 11(a), the contour of the boss portion 32 located on the bottom side of the recess 220 rather than the plate portion 31 is shown by a broken line. The holding portion 320 is a space formed so as to open toward the first side wall portion 221 in a state where the boss portion 32 is fitted into the recess 220. The boss portion 32 has a shape for holding the adhesive 7 injected into the holding portion 320 at a portion suitable for fixing the linear portion 402 of the signal line portion 400. In the present embodiment, as shown in FIGS. 11(a) and 13(a), the shape of the boss portion 32 when viewed from the axial direction is a U shape formed so as to surround the holding portion 320 from three sides.

[0042] An opening 310 for injecting the uncured adhesive 7 into the holding portion 320 is formed in the plate portion 31 of the cover member 3. As shown in FIG. 11(a), when the cover member 3 is viewed from the axial direction, the opening 310 is smaller than the holding portion 320. The adhesive 7 is, for example, a thermosetting epoxy-based adhesive, and is cured by being heated after being injected into the holding portion 320. Note that the adhesive 7 is not limited to thermosetting, and may be, for example, photocurable.

[0043] The adhesive 7 adheres to at least the inner surface 320a of the holding portion 320, the bottom surface 220c of the recess 220, and the linear portion 402 of the flexible substrate 4. Thereby, the linear portion 402 of the flexible substrate 4 is fixed to the holder 2 and the cover member 3. In the present embodiment, the adhesive 7 adheres to one surface 4a of the flexible substrate 4 in the linear portion 402, and the other surface 4b abuts against the first inner wall surface 220a of the first side wall portion 221. Note that the adhesive 7 may be interposed between the other surface 4b of the flexible substrate 4 in the linear portion 402 and the first inner wall surface 220a.

[0044] A first notch 224 for holding one end of the plate portion 31 of the cover member 3 in the arrangement direction of the first side wall portion 221 and the second side wall portion 222 is formed in the first side wall portion 221. A second notch 225 for holding the other end of the plate portion 31 of the cover member 3 in the arrangement direction of the first side wall portion 221 and the second side wall portion 222 is formed in the second side wall portion 222. The first notch 224 has an opposing surface 224a that opposes one end surface 31a of the plate portion 31, and the second notch 225 has an opposing surface 225a that opposes the other end surface 31b of the plate portion 31. The back surface 31c, which is the surface of the plate portion 31 on the side of the boss portion 32, is supported by the support surface 224b of the first notch 224 and the support surface 225b of the second notch 225. The support surfaces 224b and 225b are planes directed in the axial direction.

[0045] As shown in FIG. 14, in the arrangement direction of the first side wall portion 221 and the second side wall portion 222 (the left - right direction in FIG. 14), the distance D1 between the end surface 32a on the first side wall portion 221 side of the boss portion 32 and the one end surface 31a of the plate portion 31 is larger than the distance D3 obtained by adding the thickness T of the flexible substrate 4 to the distance D2 between the opposing surface 224a of the first notch 224 and the first inner wall surface 220a in the same direction. Thereby, a gap S is formed between the end surface 32a of the boss portion 32 and the linear portion 402 of the flexible substrate 4, so that the linear portion 402 of the flexible substrate 4 is not pressed by the boss portion 32. Further, the adhesive 7 before curing enters the gap S, and the adhesive strength of the linear portion 402 is increased.

[0046] According to the first embodiment described above, since the linear portion 402 of the flexible substrate 4 is led out to the outside of the holder 2, there is no need to connect the flexible substrate 4 to a cable inside the holder 2, and the magnetostrictive torque sensor 1 can be miniaturized. Therefore, even when the installation space around the rotating shaft 9 is narrow, it becomes easier to install the magnetostrictive torque sensor 1. Further, since the linear portion 402 of the flexible substrate 4 is fixed to the protrusion 22 of the holder 2, even when the linear portion 402 is pulled by an external force, the force is not transmitted to the detection portion 40 of the flexible substrate 4, and the distance between the detection portion 40 and the outer peripheral surface 21a of the cylindrical portion 21 of the holder 2 is prevented from fluctuating, and a decrease in detection accuracy is suppressed.

[0047] [Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. 15 to 17. FIG. 15 is an exploded perspective view of a magnetostrictive torque sensor 1A according to the second embodiment. FIG. 16(a) is a partial cross-sectional view of the magnetostrictive torque sensor 1A. FIG. 16(b) is an enlarged view of part E in FIG. 16(a). FIG. 17 is a partial enlarged view of the magnetostrictive torque sensor 1A viewed from the direction of arrow F in FIG. 16(a). In FIGS. 15 to 17, for the components described in the first embodiment, the same reference numerals as those given in FIGS. 1 to 14 are used, and redundant descriptions are omitted.

[0048] In the first embodiment, the case where the adhesive 7 is used as the fixing member for fixing a part of the longitudinal direction of the linear portion 402 of the flexible substrate 4 to the holder 2 has been described. However, in the second embodiment, an adhesive tape 8 is used as the fixing member. Further, in the first embodiment, the case where the opening 310 is formed in the plate portion 31 of the cover member 3 and the holding portion 320 is formed in the boss portion 32 has been described. However, the cover member 3A of the second embodiment has no opening 310 formed in the plate portion 31 and no holding portion 320 formed in the boss portion 32. The configurations of the holder 2 and the flexible substrate 4 are the same as those in the first embodiment.

[0049] As shown in Fig. 16(b), the adhesive tape 8 of this embodiment is a double-sided tape in which first and second adhesive layers 81 and 82 are provided on both sides of a strip-shaped base material 80. The base material 80 is made of, for example, paper, non-woven fabric, or a resin film. The first and second adhesive layers 81 and 82 are made of, for example, adhesives such as acrylic, rubber, polyurethane, and silicone. The first adhesive layer 81 adheres to the first inner wall surface 220a of the first side wall portion 221, and the second adhesive layer 82 adheres to the other surface 4b of the flexible substrate 4 in the linear portion 402.

[0050] The linear portion 402 of the flexible substrate 4 is covered by the cover member 3A at the portion fixed to the holder 2 by the adhesive tape 8. As a result, it is possible to prevent an external force from being directly applied to the linear portion 402 of the portion fixed to the holder 2 by the adhesive tape 8, and to prevent the first adhesive layer 81 of the adhesive tape 8 from peeling off from the first inner wall surface 220a of the first side wall portion 221, and to prevent the linear portion 402 of the flexible substrate 4 from peeling off from the second adhesive layer 82 of the adhesive tape 8.

[0051] In Fig. 17, as described with reference to Fig. 14 in the first embodiment, the dimensional relationships of each part in the vicinity of the lead-out portion of the linear portion 402 of the flexible substrate 4 from the holder 2 are shown. In the second embodiment, as shown in Fig. 17, in the arrangement direction of the first side wall portion 221 and the second side wall portion 222 (the left-right direction in Fig. 17), the distance D4 between the end surface 32a on the first side wall portion 221 side of the boss portion 32 and the end surface 31a of the plate portion 31 is the distance D6 obtained by adding the thickness T1 of the flexible substrate 4 and the thickness T2 of the adhesive tape 8 to the distance D5 between the opposing surface 224a of the first notch 224 and the first inner wall surface 220a in the same direction. As a result, a gap S1 is formed between the end surface 32a of the boss portion 32 and the linear portion 402 of the flexible substrate 4 so that the linear portion 402 of the flexible substrate 4 is not pressed by the boss portion 32. The width of the gap S1 in the thickness direction of the linear portion 402 of the flexible substrate 4 and the adhesive tape 8 (the distance between one surface 4a of the flexible substrate 4 and the end surface 32a of the boss portion 32) is, for example, not less than 0.5 times and less than 5.0 times the thickness T1 of the flexible substrate 4.

[0052] When the gap S1 is formed as described above, even if the linear portion 402 of the flexible substrate 4 is pulled in the direction of arrow G in FIG. 16(a) (the direction from the first side wall portion 221 side to the second side wall portion 222 side), between the boss portion 32 of the cover member 3A and the first side wall portion 221, this pulling force is converted into a force in the longitudinal direction of the linear portion 402. As a result, it is possible to suppress the first adhesive layer 81 of the adhesive tape 8 from peeling off from the first inner wall surface 220a of the first side wall portion 221 and the linear portion 402 from peeling off from the second adhesive layer 82 of the adhesive tape 8.

[0053] When assembling the magnetostrictive torque sensor 1A, the linear portion 402 of the flexible substrate 4 is attached to the first side wall portion 221 of the holder 2 by the adhesive tape 8, and then the cover member 3A is assembled to the holder 2. When attaching the linear portion 402 of the flexible substrate 4 by the adhesive tape 8, the linear portion 402 and the adhesive tape 8 are pressed against the first side wall portion 221 by fingers or tools. Since the holder 2 is formed with a recess 220, the space of the recess 220 can be utilized as a working space, and this operation can be easily performed.

[0054] Here, the case where the adhesive tape 8 is a double-sided tape has been described, but it is not limited to this. An adhesive tape (single-sided tape) having an adhesive layer formed only on one surface of the base material may be used as a fixing member for fixing a part in the longitudinal direction of the linear portion 402 of the flexible substrate 4 to the holder 2. In this case, an adhesive tape having a width wider than the width dimension in the width direction of the linear portion 402 may be used, the adhesive tape may be attached to one surface 4a of the linear portion 402, and portions on both sides in the width direction of the linear portion 402 of the adhesive tape may be attached to the holder 2.

[0055] (Summary of Embodiment) Next, the technical idea grasped from the above-described embodiments will be described by referring to the reference numerals and the like in the embodiments. However, each reference numeral in the following description is not limited to the members and the like that specifically show the components in the claims in the embodiments.

[0056] [1] A magnetostrictive torque sensor (1, 1A) attached around a rotating shaft (9) having a magnetostrictive effect and detecting the torque transmitted by the rotating shaft (9), comprising: a cylindrical portion (21) having a cavity (20) through which the rotating shaft (9) is inserted formed at the center; and a holder (2) having a protrusion (22) provided to protrude radially outward from the cylindrical portion (21); a detection portion (40) in which a coil group (4A to 4D) formed by combining a plurality of detection coils (410 to 419, 420 to 429, 430 to 439, 440 to 449) arranged in a predetermined direction is formed by a wiring pattern; and a flexible substrate (4) having a signal line portion (400) in which a plurality of signal lines (491 to 494) electrically connecting the coil group (4A to 4D) and an external device (6) are formed by a wiring pattern. The detection portion (40) is wound around the outer periphery of the cylindrical portion (21) of the holder (2), and the signal line portion (400) has a part in the longitudinal direction fixed to the protrusion (22) of the holder (2) by a fixing member (adhesive 7, adhesive tape 8), and the tip side from the fixed portion is led out to the outside of the holder (2). Magnetostrictive torque sensor (1, 1A).

[0057] [2] The magnetostrictive torque sensor (1, 1A) according to [1] above, wherein the fixing member (7, 8) is an adhesive or an adhesive tape.

[0058] [3] The detection portion (40) is rectangular in shape with the arrangement direction of the plurality of detection coils (410 to 419, 420 to 429, 430 to 439, 440 to 449) being the long side direction, and the signal line portion (400) has a protruding piece portion (401) protruding from the detection portion (40) in a direction perpendicular to the long side direction, and a linear portion (402) extending from the protruding piece portion (401) in the long side direction. A part of the longitudinal direction of the linear portion (402) is fixed to the protrusion (22) of the holder (2) by the fixing member (7, 8). Magnetostrictive torque sensor (1, 1A) according to [1] or [2] above.

[0059] [4] In the protrusion (22) of the holder, a recess (220) for accommodating a part of the linear part (402) is formed to be recessed in the axial direction of the cylindrical part (21). The linear part (402) is bent inside the recess (220) and led out to the outside of the holder (2) so as to extend in a direction perpendicular to the circumferential direction of the cylindrical part (21). The magnetostrictive torque sensor (1, 1A) according to [3] above, wherein the linear part (402) is fixed by the fixing members (7, 8) so as to face the inner wall surface (220a) of the recess (220).

[0060] [5] The magnetostrictive torque sensor (1, 1A) according to [4] above, wherein the inner wall surface (220a) to which the linear part (402) is fixed by the fixing members (7, 8) is parallel to the leading-out direction of the linear part (402) from the holder (2).

[0061] [6] The magnetostrictive torque sensor (1, 1A) according to [4] above, further comprising a cover member (3, 3A) having a boss part (32) fitted into the recess (220).

[0062] [7] The magnetostrictive torque sensor (1) according to [6] above, wherein the fixing member is an adhesive (7), and a holding part (320) for holding the adhesive (7) is formed on the cover member (3).

[0063] [8] The magnetostrictive torque sensor (1A) according to [6] above, wherein the fixing member is an adhesive tape (8), and the portion where the linear part (402) is fixed by the adhesive tape (8) is covered by the cover member (3A).

[0064] As described above, the first and second embodiments of the present invention have been described. However, these embodiments do not limit the invention according to the claims. It should also be noted that not all combinations of the features described in the embodiments are essential means for solving the problems of the invention.

Explanation of Reference Numerals

[0065] 1, 1A... Magnetostrictive torque sensor 2… Holder 20… Cavity 21… Cylindrical part 22… Protrusion 220… Recess 220a… First inner wall surface 221… First side wall part 3, 3A… Cover member 31… Plate part 32… Boss part 320… Holding part 4… Flexible substrate 40… Detection part 400… Signal line part 401… Tab part 402… Linear part 410~419, 420~429, 430~439, 440~449… Detection coil 491~494… Signal line 4A~4D… Coil group 7… Adhesive 8… Adhesive tape 9… Rotation axis

Claims

1. A magnetostrictive torque sensor attached around a rotating shaft having a magnetostrictive effect, for detecting torque transmitted by the rotating shaft, a holder having a cylindrical portion with a cavity through which the rotating shaft is inserted formed at the center, and a protrusion provided to protrude radially outward from the cylindrical portion, a detection portion in which a coil group formed by combining a plurality of detection coils arranged in a predetermined direction is formed by a wiring pattern, and a signal line portion in which a plurality of signal lines electrically connecting the coil group and an external device are formed by a wiring pattern, a flexible substrate having, the detection portion is wound around the outer periphery of the cylindrical portion of the holder, a part of the signal line portion in the longitudinal direction is fixed to the protrusion of the holder by a fixing member, and the tip side from the fixed portion is led out to the outside of the holder, a magnetostrictive torque sensor.

2. The fixing member is an adhesive or an adhesive tape, The magnetostrictive torque sensor according to claim 1.

3. the detection portion has a rectangular shape in which the arrangement direction of the plurality of detection coils is the long side direction, the signal line portion has a protruding piece portion protruding from the detection portion in a direction perpendicular to the long side direction, and a linear portion extending from the protruding piece portion in the long side direction, a part of the longitudinal direction of the linear portion is fixed to the protrusion of the holder by the fixing member, The magnetostrictive torque sensor according to claim 1 or 2.

4. a recess for accommodating a part of the linear portion is formed in the protrusion of the holder so as to be recessed in the axial direction of the cylindrical portion, the linear portion is bent inside the recess and led out to the outside of the holder so as to extend in a direction perpendicular to the circumferential direction of the cylindrical portion, the linear portion is fixed by the fixing member so as to face the inner wall surface of the recess, The magnetostrictive torque sensor according to claim 3.

5. the inner wall surface to which the linear portion is fixed by the fixing member is parallel to the leading direction of the linear portion from the holder, The magnetostrictive torque sensor according to claim 4.

6. further comprising a cover member having a boss portion fitted into the recess, The magnetostrictive torque sensor according to claim 4.

7. the fixing member is an adhesive, a holding portion for holding the adhesive is formed on the cover member, The magnetostrictive torque sensor according to claim 6.

8. the fixing member is an adhesive tape, The portion where the linear part is fixed by the adhesive tape is covered by the cover member. The magnetostrictive torque sensor according to claim 6.

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