Magnetostrictive torque sensor

Abstract

To materialize a magnetostrictive torque sensor which is in such a state that the main body part of a flexible board is wrapped around the circumference of a bobbin part, and which easily maintains the above state even in a long period of use.SOLUTION: A magnetostrictive torque sensor comprises: a holder 4 having a bobbin part 6 disposed around a rotary shaft 2; and a flexible board 5 including a detection part 10 composed of a plurality of detection coils and having a main body part 11 disposed in such a way as to wrap around the bobbin part 6. The main body part 11 includes a one-side engaging part provided at one end in the circumferential direction and an other-side engaging part provided at the other end in the circumferential direction, the one-side engaging part and the other-side engaging part are engaged with each other.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a magnetostrictive torque sensor that measures torque applied to a rotating shaft. [Background technology]

[0002] As a sensor for measuring torque applied to a rotating shaft, a magnetostrictive torque sensor that measures the torque applied to a rotating shaft by utilizing the inverse magnetostrictive effect that occurs in the rotating shaft when torque is applied to the rotating shaft has been known for some time, as described in JP 2022-74405 A, for example.

[0003] The conventional magnetostrictive torque sensor described in JP 2022-74405 A includes a holder (first resin member) having a bobbin portion (inner cylindrical portion) arranged around a rotating shaft, and a flexible substrate having a main body portion arranged around the bobbin portion, which includes a detection portion consisting of multiple detection coils. The magnetostrictive torque sensor detects the torque applied to the rotating shaft based on changes in inductance of the detection coils. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2022-74405 Summary of the Invention [Problem to be solved by the invention]

[0005] The conventional magnetostrictive torque sensor described in JP 2022-74405 A is obtained by punching a base material to obtain a flexible substrate having a belt-shaped or rectangular plate-shaped main body portion, and then winding the main body portion around the bobbin portion of a holder to form it into a cylindrical or partially cut cylindrical shape.

[0006] In this case, in order to maintain the main body portion in a state in which it is wound around the bobbin portion, it is conceivable to adhere the inner surface of the main body portion to the outer surface of the bobbin portion.

[0007] However, if the inner surface of the main body portion is bonded to the outer surface of the bobbin portion, the adhesive strength may decrease due to repeated expansion and contraction of the bobbin portion due to temperature changes during use, and the inner surface of the main body portion may peel off from the outer surface of the bobbin portion.

[0008] The present disclosure aims to realize a magnetostrictive torque sensor that can easily maintain the state in which the main body portion of the flexible substrate is wound around the bobbin portion of the holder, even after long-term use. [Means for solving the problem]

[0009] The magnetostrictive torque sensor according to the first aspect of the present disclosure includes: a holder having a bobbin portion disposed around a rotation axis; a flexible substrate including a detection unit made up of a plurality of detection coils and a main body portion arranged to be wound around the bobbin portion; Equipped with.

[0010] In particular, in the magnetostrictive torque sensor of the first aspect of the present disclosure, the main body has a one-side engaging portion provided at an end on one side in the circumferential direction and an other-side engaging portion provided at an end on the other side in the circumferential direction, and the one-side engaging portion and the other-side engaging portion are engaged with each other.

[0011] A magnetostrictive torque sensor according to a second aspect of the present disclosure is the magnetostrictive torque sensor according to the first aspect of the present disclosure, The one-side engaging portion is configured to include a through hole, The other side engagement portion is configured to include an insertion portion that is inserted into the through hole, and a slip-out prevention portion that is connected to the tip of the insertion portion and has an axial width dimension that is larger than the axial width dimension of the through hole and larger than the axial width dimension of the insertion portion.

[0012] A magnetostrictive torque measurement device according to a third aspect of the present disclosure is the magnetostrictive torque measurement device according to the first aspect of the present disclosure, the one-side engaging portion extends in the axial direction and includes a one-side slit that opens to an end edge portion on one side in the axial direction, The other-side engaging portion extends in the axial direction, opens at an edge portion on the other axial side, and includes a other-side slit that engages with the one-side engaging portion. [Effects of the Invention]

[0013] According to the magnetostrictive torque sensor of one aspect of the present disclosure, the main body of the flexible substrate can easily be maintained in a state where it is wound around the bobbin portion of the holder, regardless of temperature changes during use. [Brief explanation of the drawings]

[0014] [Figure 1] FIG. 1 is a schematic diagram of a cross section of a magnetostrictive torque sensor according to a first embodiment of the present disclosure, cut along an imaginary plane including the central axis of a rotation shaft. [Figure 2] FIG. 2 is a partially enlarged cross-sectional view showing a part of the flexible substrate that constitutes the magnetostrictive torque sensor of the first example. [Figure 3] 3(a) to 3(d) are developments of the first to fourth wiring layers as viewed from the outside in the radial direction. [Figure 4] FIG. 4 is a diagram schematically showing a detection circuit including four detection coils. [Figure 5] FIG. 5 is a plan view showing the flexible substrate of the first example in an unfolded state. [Figure 6] Figure 6(a) is a view of the engaging portion between the ends on both circumferential sides of the main body that constitutes the flexible substrate of the first example, viewed from the radial outside, and Figure 6(b) is a view of the engaging portion from the bottom of Figure 6(a). [Figure 7]Figures 7(a) to 7(c) are diagrams showing an example of the procedure for engaging the circumferential ends of the main body part constituting the first example flexible substrate, specifically, diagrams showing a partially cutaway view from the circumferential direction. [Figure 8] FIG. 8 is a plan view showing an unfolded state of a flexible substrate constituting a magnetostrictive torque sensor according to a second embodiment of the present disclosure. [Figure 9] Figure 9(a) is a view of the engaging portion between the ends on both circumferential sides of the main body that constitutes the flexible substrate of the second example, viewed from the radial outside, and Figure 9(b) is a view of the engaging portion from the bottom of Figure 9(a). [Figure 10] Figures 10(a) to 10(d) are diagrams showing an example of the procedure for engaging the circumferential ends of the main body constituting the flexible substrate of the second example, specifically, views from the radially outer side. DETAILED DESCRIPTION OF THE INVENTION

[0015] [Example 1] A first example of an embodiment of the present disclosure will be described with reference to FIGS. 1 to 7(c).

[0016] The magnetostrictive torque sensor 1 is used to measure the torque transmitted by the rotating shaft 2 .

[0017] In the following description, unless otherwise specified, the axial, radial, and circumferential directions of the magnetostrictive torque sensor 1 refer to the axial, radial, and circumferential directions of the rotating shaft 2. The axial, radial, and circumferential directions of the rotating shaft 2 coincide with the axial, radial, and circumferential directions of the holder 4 and also coincide with the axial, radial, and circumferential directions of the back yoke 32. Furthermore, one axial side refers to the left side in FIG. 1, and the other axial side refers to the right side in FIG. 1.

[0018] The rotating shaft 2 has a detection target 3, which is a cylindrical surface whose outer diameter does not change in the axial direction, on part of its outer peripheral surface in the axial direction. The rotating shaft 2 is rotatably supported via a bearing (not shown) on a fixed part that does not rotate even during use.

[0019] The rotating shaft 2 is made of a material having magnetostrictive properties in part or in whole, including at least the detected portion 3. Specifically, the rotating shaft 2 can be made of an iron alloy such as, but not limited to, SC (carbon steel for mechanical construction), SUS (stainless steel), SCr (chromium steel), SCM (chromium molybdenum steel), or SNCM (nickel chromium molybdenum steel).

[0020] The magnetostrictive torque sensor 1 includes a holder 4 and a flexible substrate 5 .

[0021] The holder 4 has a bobbin portion 6 arranged around the rotation shaft 2 .

[0022] In this example, the bobbin portion 6 is configured to have a cylindrical shape. However, the bobbin portion 6 may also be configured to have a partially cut cylindrical shape.

[0023] The holder 4 is supported and fixed to a fixed portion that does not rotate during use, such as a housing, with the bobbin portion 6 arranged coaxially around the detection target portion 3 of the rotating shaft 2. With the holder 4 supported and fixed to the fixed portion, the inner peripheral surface of the bobbin portion 6 faces the detection target portion 3 of the rotating shaft 2 with a radial gap between them, and does not come into contact with the detection target portion 3.

[0024] The holder 4 is made of synthetic resin, which is a non-magnetic and non-conductive (insulating) material. Specifically, the holder 4 is made of epoxy resin or a thermoplastic resin such as PPS (polyphenylene sulfide), PA (polyamide), or PPA (polyphthalamide). In this example, the holder 4 is integrally formed by injection molding of the synthetic resin. However, when implementing the magnetostrictive torque sensor of the present disclosure, the holder can also be formed by combining multiple parts.

[0025] In this example, the holder 4 has, as optional elements, a first outward flange portion 7 extending radially outward from the end on one axial side of the bobbin portion 6 around the entire circumference, and a second outward flange portion 8 extending radially outward from the end on the other axial side of the bobbin portion 6 around the entire circumference.

[0026] The first outward flange portion 7 has an attachment portion for supporting and fixing the holder 4 to the fixed portion, and / or a wiring accommodating portion for accommodating cables and / or signal lines that electrically connect the detection coils 9a to 9d provided on the flexible substrate 5 to the external device 27.

[0027] In this example, the outer diameter of the first outward flange portion 7 is larger than the outer diameter of the second outward flange portion 8. However, the outer diameter of the first outward flange portion 7 can be the same as the outer diameter of the second outward flange portion 8, or can be smaller than the outer diameter of the second outward flange portion 8.

[0028] The flexible substrate 5 has a main body 11 that includes a detection section 10 made up of a plurality of detection coils 9a to 9d and is arranged so as to be wound around the bobbin section 6.

[0029] The magnetostrictive torque sensor 1 detects the change in magnetic permeability of the rotating shaft 2 that occurs when the rotating shaft 2 transmits torque based on the inverse magnetostrictive effect using a detection unit 10 consisting of multiple detection coils 9a to 9d, and measures the torque transmitted by the rotating shaft 2.

[0030] The flexible substrate 5 is configured to be elastically deformable by arranging wiring layers 13a to 13d made of conductors on or inside base films 12a and 12b made of insulating material. In the unfolded state of the flexible substrate 5 shown in Fig. 5, the main body 11 provided with the detection unit 10 is configured as a strip or a substantially rectangular plate as a whole. In the assembled state of the magnetostrictive torque sensor 1, the main body 11 is wound around the bobbin part 6 of the holder 4 and formed into a cylindrical shape.

[0031] The flexible substrate 5 has a laminated structure having a plurality of wiring layers 13a to 13d each provided with a detection coil 9a to 9d. Each of the wiring layers 13a to 13d is made up of a wiring pattern formed by etching a copper foil, which is a conductor.

[0032] The wiring layers 13a to 13d are formed on the surfaces of the base films 12a and 12b, respectively, and are covered with the coverlay films 14a to 14d. The coverlay films 14a to 14d, the wiring layers 13a to 13d, and the base films 12a and 12b are bonded together by adhesive layers 15a to 15d.

[0033] In this example, the flexible substrate 5 has four wiring layers 13a to 13d according to the number and arrangement of the detection coils 9a to 9d.

[0034] Specifically, as shown in Figure 2, the flexible substrate 5 is constructed by stacking, from the radially outer side, a first coverlay film 14a, a first adhesive layer 15a, a first wiring layer 13a, a first base film 12a, a second wiring layer 13b, a second adhesive layer 15b, a second coverlay film 14b, a central adhesive layer 16, a third coverlay film 14c, a third adhesive layer 15c, a third wiring layer 13c, a second base film 12b, a fourth wiring layer 13d, a fourth adhesive layer 15d, and a fourth coverlay film 14d.

[0035] Each of the coverlay films 14a to 14d and the base films 12a and 12b is made of a thin film of an insulating material such as polyimide, polyester, etc. The coverlay films 14a to 14d are protective films for protecting the wiring layers 13a to 13d.

[0036] The first wiring layer 13a is formed on the radially outer surface of the first base film 12a, the second wiring layer 13b is formed on the radially inner surface of the first base film 12a, the third wiring layer 13c is formed on the radially outer surface of the second base film 12b, and the fourth wiring layer 13d is formed on the radially inner surface of the second base film 12b.

[0037] The adhesive layers 15a to 15d are made of an adhesive that bonds the coverlay films 14a to 14d, the wiring layers 13a to 13d, and the base films 12a and 12b together, respectively. The central adhesive layer 16 is made of an adhesive that bonds the second coverlay film 14b and the third coverlay film 14c together.

[0038] Specifically, each of the adhesive layers 15a to 15d and the central adhesive layer 16 is made of an epoxy resin or acrylic resin adhesive.

[0039] In this example, the first detection coil 9a is formed on the first wiring layer 13a, the second detection coil 9b is formed on the second wiring layer 13b, the third detection coil 9c is formed on the third wiring layer 13c, and the fourth detection coil 9d is formed on the fourth wiring layer 13d.

[0040] The number, configuration, and arrangement of the multiple detection coils 9a to 9d are not particularly limited as long as they can detect changes in the magnetic permeability of the rotating shaft 2. For example, the multiple detection coils 9a to 9d can be arranged overlapping each other in the radial direction and / or arranged side by side in the axial direction.

[0041] In this example, the multiple detection coils 9a to 9d are configured by four detection coils 9a to 9d arranged to overlap in the radial direction. Specifically, the four detection coils 9a to 9d are arranged to overlap in the order of the first detection coil 9a, the second detection coil 9b, the third detection coil 9c, and the fourth detection coil 9d from the outside in the radial direction.

[0042] As shown in FIGS. 3(a) to 3(d), each of the four detection coils 9a to 9d is configured by arranging a plurality of coil pieces 25a to 25d, 26a to 26d in the circumferential direction.

[0043] Specifically, the first detection coil 9a is constructed by connecting in series a plurality of coil pieces 25a, 26a arranged in the circumferential direction, the second detection coil 9b is constructed by connecting in series a plurality of coil pieces 25b, 26b arranged in the circumferential direction, the third detection coil 9c is constructed by connecting in series a plurality of coil pieces 25c, 26c arranged in the circumferential direction, and the fourth detection coil 9d is constructed by connecting in series a plurality of coil pieces 25d, 26d arranged in the circumferential direction.

[0044] Of the coil pieces 25a to 25d, 26a to 26d, the coil pieces 25a to 25d located at both ends in the circumferential direction are configured by arranging the wiring pattern so as to be wound in an approximately triangular shape when viewed from the radial direction, and the remaining coil pieces 26a to 26d are configured by arranging the wiring pattern so as to be wound in an approximately parallelogram shape when viewed from the radial direction.

[0045] The coil pieces 25a and 26a constituting the first detection coil 9a and the coil pieces 25c and 26c constituting the third detection coil 9c have straight line portions inclined at a predetermined angle (for example, +45 degrees) in a predetermined direction with respect to the axial direction of the rotation shaft 2 (the direction of the short side of the detection unit 10 when the flexible substrate 5 is unfolded). The coil pieces 25b and 26b constituting the second detection coil 9b and the coil pieces 25d and 26d constituting the fourth detection coil 9d have straight line portions inclined at a predetermined angle (for example, -45 degrees) in a direction opposite to the predetermined direction with respect to the axial direction of the rotation shaft 2.

[0046] The four detection coils 9a to 9d are electrically connected to an external device 27.

[0047] The external device 27 includes an oscillator 28 that applies a voltage between two points, and a voltmeter 29 that detects the voltage between the two points.

[0048] There are no particular limitations on the manner in which the detection coils 9a to 9d are electrically connected to the external device 27. In this example, the detection coils 9a to 9d are electrically connected to the external device 27 by signal lines 30a to 30d (see FIG. 4, not shown in other figures) formed on the wiring layers 13a to 13d of the flexible substrate 5, and by cables connected to the external device 27.

[0049] That is, the flexible substrate 5 of this example includes a signal line portion 31 (see FIG. 5) extending radially and / or axially from the main body portion 11. The signal line portion 31 includes four stacked signal wires 30a to 30d. In this example, the main body portion 11 is positioned circumferentially relative to the bobbin portion 6 by engaging the signal line portion 31 with a part of the holder 4 (for example, an engaging portion provided on the first outward flange portion 7).

[0050] Of the four signal lines 30a to 30d, the first signal line 30a connects one end of the first detection coil 9a and one end of the second detection coil 9b in series, and is electrically connected to one terminal of the oscillator 28 via the cable.

[0051] The second signal line 30b connects one end of the third detection coil 9c and one end of the fourth detection coil 9d in series, and is electrically connected to the other terminal of the oscillator 28 via the cable.

[0052] The third signal line 30c connects the other end of the first detection coil 9a and the other end of the third detection coil 9c in series, and is electrically connected to one terminal of the voltmeter 29 via the cable.

[0053] The fourth signal line 30d connects the other end of the second detection coil 9b and the other end of the fourth detection coil 9d in series, and is electrically connected to the other terminal of the voltmeter 29 via the cable.

[0054] Oscillator 28 applies an AC voltage between a contact point A between one end of first detection coil 9a and one end of second detection coil 9b, and a contact point B between one end of third detection coil 9c and one end of fourth detection coil 9d. Voltmeter 29 detects the voltage between a contact point C between the other end of first detection coil 9a and the other end of third detection coil 9c, and a contact point D between the other end of second detection coil 9b and the other end of fourth detection coil 9d. In other words, the four detection coils 9a to 9d that make up detection unit 10, together with oscillator 28 and voltmeter 29, form a bridge circuit.

[0055] When torque T is applied to the rotating shaft 2, stresses σ with opposite signs act on the outer surface of the rotating shaft 2 in a direction inclined at +45° to the axial direction and a direction inclined at -45° to the axial direction. Due to the inverse magnetostriction effect, the magnetic permeability increases in the direction in which tensile stress (+σ) acts, and decreases in the direction in which compressive stress (-σ) acts. In the magnetostrictive torque sensor 1 of this example, the voltage of the bridge circuit, which changes in accordance with the change in magnetic permeability of the rotating shaft 2, is detected by a voltmeter 29, and the direction and magnitude of the torque transmitted by the rotating shaft 2 are determined based on this detected value.

[0056] The main body 11 has a one-side engaging portion 17 provided at one circumferential end thereof and a second-side engaging portion 18 provided at the other circumferential end thereof. The one-side engaging portion 17 and the second-side engaging portion 18 are engaged with each other. This maintains the main body 11 in a state in which it is wound around the bobbin portion 6. The one-side engaging portion 17 is provided at one circumferential end of the main body 11 where the detection coils 9a to 9b (see FIG. 3) that constitute the detection unit 10 are not formed, and the second-side engaging portion 18 is provided at the other circumferential end of the main body 11 where the detection coils 9a to 9b that constitute the detection unit 10 are not formed.

[0057] With respect to the flexible substrate 5, the circumferential direction coincides with the long side direction (left-right direction in Figure 5) of the main body portion 11 when the flexible substrate 5 is in the unfolded state, and the axial direction coincides with the short side direction (up-down direction in Figure 5) of the main body portion 11 when the flexible substrate 5 is in the unfolded state.

[0058] The shapes of the one-side engaging portion 17 and the other-side engaging portion 18 are not particularly limited, as long as they are configured to engage with each other so that the main body portion 11 can be maintained in a state in which it is wrapped around the bobbin portion 6.

[0059] In this example, the one-side engaging portion 17 is configured to include a through-hole 19 .

[0060] In this example, the one-side engaging portion 17 is a portion that exists within the range indicated by α when the flexible substrate 5 is in the unfolded state shown in FIG. 5, and has a rectangular plate shape.

[0061] In this example, the one-side engaging portion 17 has an axial width dimension W of a circumferentially intermediate portion 20 of the main body 11, which is a portion sandwiched between the one-side engaging portion 17 and the other-side engaging portion 18 in the circumferential direction. 20 The axial width dimension W is the same as 17 The through hole 19 penetrates the center of the one-side engaging portion 17 in the plate thickness direction.

[0062] In this example, the through-hole 19 is configured as a circular hole. However, when implementing the present disclosure, the through-hole 19 may also be configured as a through-hole of various shapes, such as an oval hole or a rectangular hole.

[0063] In this example, the other side engagement portion 18 includes an insertion portion 21 that is inserted into the through hole 19, and a retaining portion 22 that is connected to the tip of the insertion portion 21 and has an axial width dimension that is larger than the axial width dimension of the through hole 19 and larger than the axial width dimension of the insertion portion 21.

[0064] In this example, the other-side engaging portion 18 is a portion that exists in the range indicated by β when the flexible substrate 5 is in the unfolded state shown in FIG. 5, and has a T-shaped plate shape.

[0065] Specifically, the insertion portion 21 has a rectangular plate shape extending from the axial center of the edge portion 24 on the other circumferential side of the circumferential intermediate portion 20 of the main body portion 11 toward the other circumferential side in the unfolded state of the flexible substrate 5 shown in Figure 5. The circumferential width dimension L of the insertion portion 21 21 is slightly larger than the circumferential width dimension La from the edge 23 on one circumferential end side of the one-side engaging portion 17 to the edge on one axial side of the through-hole 19 (L 21 >La). The axial width dimension W of the insertion portion 21 21 is the axial width dimension (diameter) D of the through hole 19 19 (W 21 <D 19 However, as long as the insertion portion can be inserted into the through-hole, the axial width of the insertion portion can be the same as or larger than the axial width of the through-hole.

[0066] The retaining portion 22 has a rectangular plate shape extending in the axial direction when the flexible substrate 5 is in the unfolded state shown in Fig. 5. The tip end (the end on the other circumferential side) of the insertion portion 21 is connected to the axial middle portion of the retaining portion 22. The circumferential width dimension L of the retaining portion 22 is 22 is the circumferential width dimension (diameter) D of the through hole 19 19 Slightly smaller than (L 22 <D 19 However, as long as the retaining portion can be inserted into the through-hole, the circumferential width of the retaining portion can be the same as or larger than the axial width of the through-hole. 22 is the axial width dimension (diameter) D of the through hole 19 19 is sufficiently larger than (W 22 >D 19 ), and in this example, the axial width dimension W 20 is the same size as (W 22 =W 20 ).

[0067] When the magnetostrictive torque sensor 1 is assembled, the one-side engaging portion 17 and the other-side engaging portion 18 are engaged with each other by inserting the tip of the insertion portion 21 into the through hole 19, as shown in Figures 6(a) and 6(b).

[0068] In this example, with the one-side engaging portion 17 and the other-side engaging portion 18 engaged with each other, the tip of the insertion portion 21 is inserted into the through-hole 19 from the radially inner side toward the radially outer side, and the retaining portion 22 is arranged in a position overlapping the radially outer side of the one-side engaging portion 17. Specifically, both axial side portions of the retaining portion 22 are arranged overlapping the radially outer side of the portions of the one-side engaging portion 17 that are on both axial sides of the through-hole 19.

[0069] However, when implementing the present disclosure, a configuration can also be adopted in which, with the one-side engaging portion 17 and the other-side engaging portion 18 engaged with each other, the tip of the insertion portion 21 is inserted into the through hole 19 from the radially outer side toward the radially inner side, and the anti-slip portion 22 is positioned in a position overlapping the one-side engaging portion 17 radially inward.

[0070] Furthermore, in this example, when the one-side engaging portion 17 and the other-side engaging portion 18 are engaged with each other, the one-side engaging portion 17 and the end portion on the other circumferential side of the circumferential intermediate portion 20 do not overlap radially, and the edge portion 23 on one circumferential side of the one-side engaging portion 17 and the edge portion 24 on the other circumferential side of the circumferential intermediate portion 20 are arranged at approximately the same position in the circumferential direction.

[0071] When implementing the present disclosure, a configuration can also be employed in which, with one-side engaging portion 17 and the other-side engaging portion 18 engaged with each other, one-side engaging portion 17 and the other circumferential end portion of circumferential intermediate portion 20 are arranged to overlap in the radial direction. In this case, however, the circumferential range of detection unit 10 on main body 11 is restricted so that the ends on both circumferential sides of detection unit 10 provided on main body 11 are not arranged to overlap in the radial direction.

[0072] In any case, when the one-side engaging portion 17 and the other-side engaging portion 18 are engaged with each other, the axial width dimension W of the retaining portion 22 is 22 The axial width dimension (diameter) of the through hole 19 is D 19 1, the retaining portion 22 is prevented from passing through the through hole 19. This prevents the engagement between the one-side engaging portion 17 and the other-side engaging portion 18 from being released, and the state in which the main body portion 11 is arranged so as to be wound around the bobbin portion 6 is maintained.

[0073] The operation of engaging the one-side engaging portion 17 and the other-side engaging portion 18 with each other can be performed, for example, as follows. First, as shown by the arrows in FIG. 7( a), both axial side portions of the retaining portion 22 are elastically bent upward toward the same radial side. Next, as shown by the arrows in FIG. 7( b), both axial side portions of the retaining portion 22 are inserted into the through-hole 19. Next, as shown by the arrows in FIG. 7( c), both axial side portions of the retaining portion 22 are elastically restored to their original shape, thereby returning the entire retaining portion 22 to its rectangular flat plate shape and inserting the tip of the insertion portion 21 into the through-hole 19.

[0074] The magnetostrictive torque sensor 1 of this example includes a back yoke 32 arranged around the main body 11 of the flexible substrate 5 as an optional component.

[0075] The back yoke 32 has the function of preventing the magnetic flux generated by the detection coils 9a to 9d from leaking to the outside. The back yoke 32 is integrally formed from a magnetic material. The back yoke 32 can be formed from, but is not limited to, a powder magnetic core obtained by applying an insulating coating to soft magnetic metal powder and then compression molding it, or a ferromagnetic material such as SUS (stainless steel).

[0076] The shape of the back yoke 32 is not limited as long as it can be arranged around the main body 11 of the flexible substrate 5, and it can be configured, for example, as a cylindrical or parted cylindrical shape. In this example, the back yoke 32 is configured as a cylindrical shape. The back yoke 32 is held by the holder 4 in a state where it is arranged around the main body 11 of the flexible substrate 5 coaxially with the main body 11. In this example, the other axial end of the back yoke 32 is externally fitted and fixed to the second outward flange portion 8, thereby holding the back yoke 32 relative to the holder 4.

[0077] The inner peripheral surface of the back yoke 32 and the outer peripheral surface of the main body 11 of the flexible substrate 5 can be arranged to be spaced apart in the radial direction, or can be arranged to be in close contact with each other without being spaced apart in the radial direction. In this example, the inner peripheral surface of the back yoke 32 and the outer peripheral surface of the main body 11 of the flexible substrate 5 are arranged to be spaced apart in the radial direction.

[0078] In the magnetostrictive torque sensor 1 of this example, the main body 11 of the flexible substrate 5 is arranged so as to be wound around the bobbin portion 6, and one-side engaging portions 17 and the other-side engaging portions 18 provided on both circumferential ends of the main body 11 are engaged with each other. Therefore, the main body 11 can be maintained in a state in which it is wound around the bobbin portion 6 for a long period of time.

[0079] [Example 2] A second example of the embodiment of the present disclosure will be described with reference to FIGS. 8 to 10(d).

[0080] In this example, the configuration of the one-side engaging portion 17a provided at one circumferential end of the main body portion 11a of the flexible substrate 5a and the configuration of the other-side engaging portion 18a provided at the other circumferential end of the main body portion 11a are different from those of the first example.

[0081] The one-side engaging portion 17a extends in the axial direction and includes a one-side slit 33 that opens at an edge portion on one side in the axial direction.

[0082] The one-side engaging portion 17a is a portion that exists within the range indicated by α when the flexible substrate 5a is in the unfolded state shown in FIG. 8, and has a rectangular plate shape.

[0083] The one-side engaging portion 17a has an axial width W 20 The axial width dimension W is the same as 17a The one-side slit 33 has a base end (rear end) P in the axial center of the circumferential center of the one-side engaging portion 17a, extends from the base end P toward one axial side (upper side in FIG. 8), and opens to an edge portion on one axial side of the one-side engaging portion 17a.

[0084] The other-side engaging portion 18a extends in the axial direction, opens at the edge portion on the other axial side, and includes an other-side slit 34 that engages with the one-side engaging portion 17a.

[0085] The other-side engaging portion 18a is a portion that exists within the range indicated by β when the flexible substrate 5a is in the unfolded state shown in FIG. 8, and has a rectangular plate shape.

[0086] The other engaging portion 18a has an axial width W 20 The axial width dimension W is the same as 18a The other-side slit 34 has a base end (rear end) Q in the axial center of the circumferential center of the other-side engaging portion 18a, extends from the base end Q toward the other axial side (downward in FIG. 8), and opens to an edge portion on the other axial side of the other-side engaging portion 18a.

[0087] In the assembled state of the magnetostrictive torque sensor, the one-side engaging portion 17a and the other-side engaging portion 18a are engaged with each other by meshing the one-side slit 33 with the other-side slit 34, as shown in Figures 9(a) and 9(b). Specifically, the portion of the one-side engaging portion 17a that is on the other axial side of the one-side slit 33 is disposed inside the other-side slit 34, and the portion of the other-side engaging portion 18a that is on one axial side of the other-side slit 34 is disposed inside the one-side slit 33. This maintains the state in which the main body portion 11a is disposed so as to be wound around the bobbin portion 6 (see Figure 1).

[0088] When the one-side engaging portion 17a and the other-side engaging portion 18a are engaged with each other, the base end P of the one-side slit 33 abuts against the base end Q of the other-side slit 34, thereby positioning the one-side engaging portion 17a and the other-side engaging portion 18a in the axial direction. In this example, in this state, the axial positions of the one-side engaging portion 17a and the other-side engaging portion 18a coincide with each other.

[0089] In this example, when the one-side engaging portion 17a and the other-side engaging portion 18a are engaged with each other, the portion of the one-side engaging portion 17a that is located on one circumferential side of the one-side slit 33 is positioned so as to overlap radially outward from the other-side engaging portion 18a, and the portion of the one-side engaging portion 17a that is located on the other circumferential side of the one-side slit 33 is positioned so as to overlap radially inward from the other-side engaging portion 18a.

[0090] However, when implementing the present disclosure, when the one-side engaging portion 17a and the other-side engaging portion 18a are engaged with each other, the portion of the one-side engaging portion 17a located on one circumferential side of the one-side slit 33 can be positioned so as to overlap radially inwardly with the other-side engaging portion 18a, and the portion of the one-side engaging portion 17a located on the other circumferential side of the one-side slit 33 can be positioned so as to overlap radially outwardly with the other-side engaging portion 18a.

[0091] As described above, in this example, when one-side engaging portion 17a and the other-side engaging portion 18a are engaged with each other, one-side engaging portion 17a and the other-side engaging portion 18a are arranged to overlap in the radial direction. In this example, even in this state, the circumferential range of detecting portion 10 on main body 11a is restricted so that both circumferential ends of detecting portion 10, which is made up of multiple detecting coils 9a-9b (see FIG. 3) provided on main body 11a, do not overlap in the radial direction.

[0092] The operation of engaging the one-side engaging portion 17a and the other-side engaging portion 18a with each other can be performed, for example, as follows. First, as shown in Fig. 10(a), the tip end portion (axial opening) of the one-side slit 33 and the tip end portion (axial opening) of the other-side slit 34 are brought into axial opposition. Next, as shown in Fig. 10(b), the tip end portion of the one-side slit 33 and the tip end portion of the other-side slit 34 are engaged. From this state, the amount of engagement between the one-side slit 33 and the other-side slit 34 is further increased, as shown in Fig. 10(c) and Fig. 10(d) in that order, until the base end portion P of the one-side slit 33 and the base end portion Q of the other-side slit 34 abut against each other.

[0093] The other configurations and effects of the second example are the same as those of the first example. [Explanation of symbols]

[0094] 1. Magnetostrictive torque sensor 2 rotation axes 3. Detected part 4 Holder 5, 5a Flexible PCB 6 Bobbin section 7 First outward flange 8 Second outward flange 9a First detection coil 9b Second detection coil 9c Third detection coil 9d Fourth detection coil 10. Detection unit 11, 11a Main body 12a First base film 12b Second base film 13a First wiring layer 13b Second wiring layer 13c Third wiring layer 13d Fourth wiring layer 14a First coverlay film 14b Second coverlay film 14c Third Coverlay Film 14d Fourth Coverlay Film 15a First adhesive layer 15b Second adhesive layer 15c Third adhesive layer 15d Fourth adhesive layer 16 Central adhesive layer 17, 17a One side engagement portion 18, 18a Other side engaging part 19 Through hole 20 Circumferential middle section 21 Insertion part 22 Retaining part 23 Edge 24 Edge 25a~25d Coil pieces 26a~26d Coil pieces 27 External equipment 28 Oscillators 29 Voltmeter 30a First signal line 30b Second signal line 30c Third signal line 30d Fourth signal line 31 Signal line section 32 Back Yoke 33 One-side slit 34 Other side slit

Claims

1. a holder having a bobbin portion disposed around a rotation axis; a flexible substrate including a detection unit made up of a plurality of detection coils and a main body portion arranged to be wound around the bobbin portion; Equipped with the main body portion has a one-side engaging portion provided at an end portion on one side in the circumferential direction and a other-side engaging portion provided at an end portion on the other side in the circumferential direction, and the one-side engaging portion and the other-side engaging portion are engaged with each other; Magnetostrictive torque sensor.

2. The one-side engaging portion is configured to include a through hole, The other-side engaging portion includes an insertion portion that is inserted into the through hole, and a retaining portion that is connected to a tip end of the insertion portion and has an axial width dimension that is larger than the axial width dimension of the through hole and is also larger than the axial width dimension of the insertion portion.

2. The magnetostrictive torque sensor according to claim 1.

3. the one-side engaging portion extends in the axial direction and includes a one-side slit that opens to an end edge portion on one side in the axial direction, the other-side engaging portion extends in the axial direction, opens at an end edge portion on the other axial side, and includes a other-side slit that engages with the one-side engaging portion.

2. The magnetostrictive torque sensor according to claim 1.

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