Torque measuring device

Abstract

To provide a torque measuring device that can prevent damage to a coil unit during assembly work and can reduce the number of components.SOLUTION: A torque measuring device 1 comprises: a case 2 that is formed of magnetic metal; a rotation shaft 3 that is rotatably arranged inside the case 2 and has a magnetostrictive effect part in which permeability changes according to torque to be transmitted; and a torque sensor 4 that is arranged around the magnetostrictive effect part and supported by the case 2. The torque sensor 4 has a coil unit 7 that is formed in a cylindrical shape with a flexible substrate having a detection coil that changes voltage in correspondence with a change in the magnetic permeability of the magnetostrictive effect part, and a holder 8 that is formed of rubber or synthetic resin and covers an outer peripheral surface and side faces on both sides in an axial direction of the coil unit 7. The torque sensor is supported on the case 2 with an outer peripheral surface of the holder 8 fitted into an inner peripheral surface of the case 2.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a torque measuring device capable of measuring torque.

Background Art

[0002] In recent years, in the field of automobiles, there has been progress in the development of a system that measures the torque transmitted by a rotating shaft that constitutes a power train, i.e., a power transmission mechanism, and uses the measurement result to perform output control of an engine or an electric motor as a power source and shift control of a transmission.

[0003] Conventionally, as a method for measuring the torque transmitted by a rotating shaft, a magnetostrictive torque measurement method is known. In the magnetostrictive torque measurement method, a torque sensor for detecting a change in the magnetic permeability of a magnetostrictive effect portion is arranged near a magnetostrictive effect portion provided in a part of the axial direction of the rotating shaft. When torque is applied to the rotating shaft and an elastic torsional deformation occurs in the magnetostrictive effect portion, the magnetic permeability of the magnetostrictive effect portion changes based on the inverse magnetostrictive effect. As a result, the output signal of the torque sensor changes corresponding to the change in the magnetic permeability of the magnetostrictive effect portion, so that the torque transmitted by the rotating shaft can be measured.

[0004] For example, Japanese Patent Publication No. 2016-200552 (Patent Document 1) and Japanese Patent Publication No. 2017-049124 (Patent Document 2) describe the specific structure of a magnetostrictive torque sensor. The torque sensors described in these publications include a coil unit and a back yoke. The coil unit is cylindrical and arranged around the magnetostrictive portion of the rotating shaft. The coil unit has a detection coil that changes voltage in response to changes in the permeability of the magnetostrictive portion. The back yoke is a component that forms the magnetic path of the magnetic field generated by the detection coil, is cylindrical and made of a magnetic material, and is arranged around the coil unit. With a torque sensor having such a configuration, the torque transmitted by the rotating shaft can be measured based on the voltage of the detection coil. Furthermore, because the back yoke is arranged around the coil unit, leakage of magnetic flux to the outside is suppressed, making it less susceptible to disturbances and improving the accuracy of torque measurement. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2016-200552 [Patent Document 2] Japanese Patent Publication No. 2017-049124 [Overview of the project] [Problems that the invention aims to solve]

[0006] In recent years, in order to reduce the thickness of magnetostrictive torque sensors, it has been considered to construct cylindrical coil units using a flexible substrate containing a detection coil. Even in such torque sensors, arranging a back yoke around the coil unit is effective in improving the accuracy of torque measurement.

[0007] However, if a coil unit, which is cylindrically constructed from a flexible substrate, is directly bonded to the inner surface of the back yoke, there is a possibility that the coil unit may be damaged by colliding with surrounding objects during assembly before the bonding process is completed. Furthermore, if the torque sensor, which is supported by a support member during use, has a back yoke that is a separate component that only serves as a magnetic path, the number of parts will increase, leading to higher manufacturing costs.

[0008] The present invention aims to provide a torque measuring device that is less likely to damage the coil unit during assembly work and can reduce the number of parts. [Means for solving the problem]

[0009] A torque measuring device according to one aspect of the present invention comprises a case, a rotating shaft, and a torque sensor.

[0010] The aforementioned case is made of magnetic metal.

[0011] The rotating shaft is rotatably arranged inside the case and has a magnetostrictive effect section whose magnetic permeability changes according to the transmitted torque.

[0012] The torque sensor is positioned around the magnetostrictive effect section and is supported by the case.

[0013] The torque sensor comprises a coil unit formed in a cylindrical shape using a flexible substrate having a detection coil that changes voltage in response to changes in the permeability of the magnetostrictive effect section, and a holder made of rubber or synthetic resin that covers the outer circumferential surface of the coil unit and has portions that protrude axially from the coil unit on both sides. The torque sensor is supported by the case with the outer circumferential surface of the holder fitted inside the inner circumferential surface of the case.

[0014] In a torque measuring device according to one aspect of the present invention, the holder includes portions that cover the axial sides of the coil unit.

[0015] In the torque measuring device according to one aspect of the present invention, the entire coil unit is embedded in the holder.

[0016] In the torque measuring device according to one aspect of the present invention, a ridge provided on the outer peripheral surface of the holder engages with a circumferential groove provided on the inner peripheral surface of the case.

[0017] In the torque measuring device according to one aspect of the present invention, an outward flange provided on the holder abuts against the axial side surface of the case.

[0018] In the torque measuring device according to one aspect of the present invention, a part of the case is sandwiched from both axial sides by two outward flanges provided on the holder.

[0019] In the torque measuring device according to one aspect of the present invention, the holder abuts against a stepped surface facing the axial direction provided on the inner peripheral surface of the case.

[0020] In the torque measuring device according to one aspect of the present invention, the holder is sandwiched from both axial sides between a stepped surface facing the axial direction provided on the inner peripheral surface of the case and an inward flange provided on the case.

Advantages of the Invention

[0021] According to the torque measuring device according to one aspect of the present invention, the coil unit is less likely to be damaged during assembly work, and the number of parts can be reduced.

Brief Description of the Drawings

[0022] [Figure 1] FIG. 1 is a cross-sectional view of a torque measuring device according to a first example of an embodiment of the present invention. [Figure 2] FIG. 2(a) is a developed view of a flexible substrate constituting the coil unit of the first example, and FIG. 2(b) is a view of the flexible substrate as seen from below in FIG. 2(a). [Figure 3]FIG. 3 is a developed view of the detection coil of the coil unit of the first example as viewed from the radially outer side. [Figure 4] FIGS. 4(a) to 4(d) are developed views of the first split coil, the second split coil, the third split coil, and the fourth split coil that constitute the detection coil of the coil unit of the first example, each viewed from the radially outer side in a single state. [Figure 5] FIG. 5 is a diagram showing the electronic circuit of the first example. [Figure 6] FIG. 6 is a diagram conceptually showing the relationship between the clearance C between the coil unit and the back yoke and the output voltage V of the electronic circuit for the torque measuring device of the first example. [Figure 7] FIG. 7 is a cross-sectional view of the torque measuring device of the second example of the embodiment of the present invention. [Figure 8] FIG. 8 is a cross-sectional view of the torque measuring device of the third example of the embodiment of the present invention. [Figure 9] FIGS. 9(a) and 9(b) are half cross-sectional views of the torque measuring device showing modified examples of the third example, respectively. [Figure 10] FIG. 10 is a cross-sectional view of the torque measuring device of the fourth example of the embodiment of the present invention. [Figure 11] FIG. 11 is a cross-sectional view of the torque measuring device of the fifth example of the embodiment of the present invention. [Figure 12] FIG. 12 is a cross-sectional view of the torque measuring device of the sixth example of the embodiment of the present invention. [Figure 13] FIG. 13 is a cross-sectional view of the torque measuring device of the seventh example of the embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

[0023] [First Example] The first example of the embodiment of the present invention will be described with reference to FIGS. 1 to 6.

[0024] The torque measuring device 1 in this example comprises a case 2, a rotating shaft 3, and a torque sensor 4, and is capable of measuring the torque transmitted by the rotating shaft 3. It is applicable to various types of mechanical devices. Specific examples of applicable mechanical devices include mechanical devices that constitute the powertrain of an automobile, such as automatic transmissions (AT), belt-type continuously variable transmissions, toroidal continuously variable transmissions, automatic manual transmissions (AMT), dual-clutch transmissions (DCT), and other transmissions that change speeds under vehicle-side control, as well as transfer cases and manual transmissions (MT). The drive system of the target vehicle, i.e., FF, FR, MR, RR, 4WD, etc., is not particularly limited. Further examples of mechanical devices into which the torque measuring device 1 in this example can be incorporated include devices that change the rotational speed of the power shaft using gears, such as reducers and speed increasers that constitute wind turbines, railway vehicles, and steel rolling mills.

[0025] In the torque measuring device 1 of this example, case 2 is an exterior component such as a casing, housing, or cover for a mechanical device that constitutes the powertrain of an automobile, and is made of a magnetic metal such as an iron alloy. In this example, case 2 has a cylindrical tubular portion 5 as shown in Figure 1.

[0026] In this example, the rotating shaft 3 is a torque transmission shaft for a mechanical device that constitutes the powertrain of an automobile, and has a magnetostrictive effect section whose magnetic permeability changes according to the transmitted torque. The rotating shaft 3 is rotatably supported by a rolling bearing (not shown) in a part of case 2 (not shown).

[0027] The rotating shaft 3 has an intermediate shaft portion 6 located inside the cylindrical portion 5 of the case 2, and arranged coaxially with the cylindrical portion 5. The outer circumferential surface of the intermediate shaft portion 6 is formed by a cylindrical surface. In this example, the intermediate shaft portion 6 of the rotating shaft 3 functions as a magnetostrictive effect portion. For this purpose, the rotating shaft 3 is made of a magnetic metal. As the magnetic metal constituting the rotating shaft 3, various magnetic steels can be used, such as carburized steels such as SCr420 and SCM420 as specified in JIS, and carbon steels such as S45C.

[0028] When torque is applied to the rotating shaft 3, causing torsional deformation in the intermediate shaft portion 6, stress corresponding to the torque acts on the intermediate shaft portion 6, namely, tensile stress in the +45° direction relative to the axial direction and compressive stress in the -45° direction relative to the axial direction. Consequently, the permeability of the intermediate shaft portion 6 in each direction changes due to the inverse magnetostrictive effect.

[0029] In carrying out the present invention, a compression work-hardened layer can be formed on the outer circumferential surface of the intermediate shaft portion 6 in the area facing the torque sensor 4 by applying shot peening treatment, thereby improving the mechanical and magnetic properties of that portion. In this way, the sensitivity and hysteresis of torque measurement by the torque measuring device 1 can be improved.

[0030] When implementing the present invention, instead of having the intermediate shaft portion 6 function as the magnetostrictive effect portion, a magnetostrictive material that functions as the magnetostrictive effect portion can be fixed to the outer circumferential surface of the intermediate shaft portion 6. Specifically, a magnetostrictive material configured in an annular shape can be fitted and fixed to the intermediate shaft portion 6, or a magnetostrictive material configured with a coating such as plating or a film-like magnetostrictive material can be fixed to the outer circumferential surface of the intermediate shaft portion 6.

[0031] In this example, the torque sensor 4 is configured in a cylindrical shape, positioned around the intermediate shaft portion 6 of the rotating shaft 3, and is internally fitted and supported within the cylindrical portion 5 of the case 2. The torque sensor 4 comprises a coil unit 7 and a holder 8. The torque sensor 4 does not have a back yoke.

[0032] The coil unit 7 is composed of a flexible printed circuit board (FPC) 10, which comprises a base film and printed wiring (conductors) held on the base film. The flexible circuit board 10 has a detection coil 9 that changes voltage in response to changes in the magnetic permeability of the intermediate shaft portion 6.

[0033] Specifically, in this example, the coil unit 7 is constructed by rolling a strip-shaped flexible substrate 10, as shown in Figure 2, into a cylindrical shape, and joining the two ends of the flexible substrate 9 in the longitudinal direction by, for example, adhesive. In this example, the detection coil 9 consists of a first divided coil 11, a second divided coil 12, a third divided coil 13, and a fourth divided coil 14 provided on the flexible substrate 10. That is, the flexible substrate 10 has four wiring layers stacked in the thickness direction, and the first divided coil 11, the second divided coil 12, the third divided coil 13, and the fourth divided coil 14, each composed of printed wiring, are arranged on these wiring layers. These divided coils are arranged in the order of the first divided coil 11, the second divided coil 12, the third divided coil 13, and the fourth divided coil 14 from the radially inner side when the strip-shaped flexible substrate 10 is rolled into a cylindrical shape, that is, when the cylindrical coil unit 7 is constructed.

[0034] Figure 3 shows an exploded view of the detection coil 9 as seen from the radially outer side of the coil unit 7. Figures 4(a) to 4(d) show exploded views of the first divided coil 11, second divided coil 12, third divided coil 13, and fourth divided coil 14, which constitute the detection coil 9, as seen from the radially outer side of the coil unit 7.

[0035] The first divided coil 11 comprises a plurality of coil pieces 15 arranged at equal pitches in the circumferential direction, as shown in Figure 4(a). These coil pieces 15 have a parallelogram shape when viewed from the radial direction and are composed of wiring inclined at +45° with respect to the axial direction of the intermediate shaft portion 6. Adjacent coil pieces 15 in the circumferential direction are connected in series by a conductor such as printed wiring (not shown). That is, in Figure 4(a), the coil pieces 15 are schematically shown and are depicted as being connected all around, but in reality, there is a discontinuity in a part of the circumferential direction of the coil piece 15. The coil piece 15 has two ends separated by this discontinuity. Adjacent coil pieces 15 in the circumferential direction are connected in series by connecting one end of each other with a conductor such as printed wiring (not shown). These points are the same for the second divided coil 12 to the fourth divided coil 14 described below.

[0036] As shown in Figure 4(b), the second divided coil 12 comprises a plurality of coil pieces 16 arranged at equal pitches in the circumferential direction. These coil pieces 16 have a parallelogram shape when viewed from the radial direction and are composed of wiring inclined at -45° with respect to the axial direction of the intermediate shaft portion 6. Adjacent coil pieces 16 in the circumferential direction are connected in series by a conductor such as printed wiring (not shown).

[0037] As shown in Figure 4(c), the third divided coil 13 comprises a plurality of coil pieces 17 arranged at equal pitches in the circumferential direction. These coil pieces 17 have a parallelogram shape when viewed from the radial direction and are composed of wiring inclined at -45° with respect to the axial direction of the intermediate shaft portion 6. Adjacent coil pieces 17 in the circumferential direction are connected in series by a conductor such as printed wiring (not shown).

[0038] As shown in Figure 4(d), the fourth segmented coil 14 comprises a plurality of coil pieces 18 arranged at equal pitches in the circumferential direction. These coil pieces 18 have a parallelogram shape when viewed from the radial direction and are composed of wiring inclined at +45° with respect to the axial direction of the intermediate shaft portion 6. Adjacent coil pieces 18 in the circumferential direction are connected in series by a conductor such as printed wiring (not shown).

[0039] When implementing the present invention, the specific shapes and arrangements of the first, second, third, and fourth segmented coils constituting the detection coil are not limited to the configuration in this example, but various conventionally known configurations can be adopted.

[0040] The holder 8 is made of rubber or synthetic resin, covers the outer circumferential surface of the coil unit 7, and includes portions that protrude axially from the coil unit 7 on both sides. In this example, the holder 8 also covers the axially side and inner circumferential surfaces of the coil unit 7. That is, in this example, the holder 8 is configured as a cylinder and covers the outer circumferential surface, axially side and inner circumferential surface of the coil unit 7 by embedding the entire coil unit 7 which is arranged coaxially with itself. When implementing the present invention, it is also possible to adopt a structure in which the portion of the holder 8 that covers the axially side of the coil unit 7 is omitted. That is, it is also possible to adopt a structure in which the holder 8 is separated into a portion located radially outward from the outer circumferential surface of the coil unit 7 and a portion located radially inward from the inner circumferential surface of the coil unit 7.

[0041] The torque sensor 4 is supported and fixed to the case 2 by fitting the outer surface of the holder 8 into the inner surface of the cylindrical portion 5 of the case 2 by a crimping fit. In this state, the coil unit 7 is arranged coaxially around the intermediate shaft portion 6 of the rotating shaft 3. When implementing the present invention, the outer surface of the holder 8 can also be adhesively fixed to the inner surface of the cylindrical portion 5 of the case 2.

[0042] The torque sensor 4 in this example further includes an electronic circuit 19 as shown in Figure 5. The electronic circuit 19 includes a first division coil 11, a second division coil 12, a third division coil 13, and a fourth division coil 14 that constitute the detection coil 9 (see Figure 3), and generates an output voltage corresponding to the voltage of the detection coil 9.

[0043] In this example, the electronic circuit 19 is composed of a bridge circuit with a first division coil 11, a second division coil 12, a third division coil 13, and a fourth division coil 14 arranged on all four sides. In addition to the first division coil 11, the second division coil 12, the third division coil 13, and the fourth division coil 14, the electronic circuit 19 also includes an oscillator 20 for applying an AC voltage between points A and B, and a lock-in amplifier 21 for detecting and amplifying the midpoint voltage (differential voltage), which is the potential difference between points C and D. Of the components that make up the electronic circuit 19, all components except the detection coil 9 can be fixed to the flexible substrate 10, for example, or to another substrate (not shown).

[0044] When using the torque measuring device 1 in this example, the oscillator 20 applies an AC voltage between points A and B of the electronic circuit 19, causing AC current to flow through the first division coil 11, the second division coil 12, the third division coil 13, and the fourth division coil 14. As a result, in the first division coil 11, the second division coil 12, the third division coil 13, and the fourth division coil 14, currents flow in opposite directions between adjacent coil pieces 15, 16, 17, and 18 in the circumferential direction, as shown by arrows α1, α2, α3, and α4 in Figures 4(a) to 4(d). In other words, adjacent coil pieces 15, 16, 17, and 18 in the circumferential direction are connected so that currents flow in these directions. As a result, an alternating magnetic field is generated around the first divided coil 11, the second divided coil 12, the third divided coil 13, and the fourth divided coil 14, and a portion of the magnetic flux of this alternating magnetic field passes through the surface layer of the intermediate shaft portion 6.

[0045] In this state, when a torque T is applied to the intermediate shaft 6 in the direction indicated by the arrow CW in Figure 1, the rotating shaft 3 is subjected to a tensile stress (+σ) in the direction of +45° relative to the axial direction and a compressive stress (-σ) in the direction of -45° relative to the axial direction. Due to the inverse magnetostrictive effect, the permeability of the intermediate shaft 6 increases in the +45° direction, which is the direction in which the tensile stress (+σ) acts, and decreases in the -45° direction, which is the direction in which the compressive stress (-σ) acts.

[0046] On the other hand, the first and fourth divided coils 11 and 14 are constructed with wiring inclined at +45° with respect to the axial direction of the intermediate shaft 6, and a portion of the magnetic flux of the alternating magnetic field generated around this wiring passes through the surface layer of the intermediate shaft 6 in the -45° direction, which is the direction in which the permeability decreases. As a result, the inductances of the first and fourth divided coils 11 and 14 decrease. Also, the second and third divided coils 12 and 13 are constructed with wiring inclined at -45° with respect to the axial direction of the intermediate shaft 6, and a portion of the magnetic flux of the alternating magnetic field generated around this wiring passes through the surface layer of the intermediate shaft 6 in the +45° direction, which is the direction in which the permeability increases. As a result, the inductances of the third and fourth divided coils 13 and 14 increase.

[0047] In contrast, when a torque T in the direction indicated by the arrow CCW in Figure 1 is applied to the intermediate shaft 6, the inductance of the first and fourth divided coils 11 and 14 increases, and the inductance of the second and third divided coils 12 decreases, due to the opposite effect to that described above.

[0048] In any case, the electronic circuit 19 detects and amplifies the midpoint voltage, which is the potential difference between point C and point D, using the lock-in amplifier 21, thereby obtaining an output voltage V corresponding to the direction and magnitude of the torque T applied to the rotating shaft 3. Therefore, this output voltage V can be used to measure the torque transmitted by the rotating shaft 3.

[0049] In this example, when measuring torque as described above, the cylindrical portion 5 that constitutes the magnetic metal case 2, which is arranged around the coil unit 7, functions as a back yoke. This suppresses leakage of magnetic flux to the outside, making it less susceptible to disturbances and improving the accuracy of torque measurement.

[0050] In the torque measuring device 1 of this example, temperature changes during use cause expansion or contraction in each component constituting the torque measuring device 1. Consequently, the radial clearance C between the outer surface of the coil unit 7 and the inner surface of the cylindrical portion 5, which functions as a back yoke, changes, and the output voltage V of the electronic circuit 19 changes accordingly.

[0051] Figure 6 is a conceptual diagram showing the relationship between the radial clearance C and the output voltage V of the electronic circuit 19 for the torque measuring device 1 in this example. Note that the diagram shown in Figure 6, including the numerical values ​​on the horizontal axis, is illustrative. The diagram shown in Figure 6 can be obtained through simulation analysis or experimentation. As shown in this diagram, within the range of radial clearance C, there is a range X1 in which linearity is shown between the change in radial clearance C and the change in the output voltage V of the electronic circuit 19, and on both sides of this range X1, there are ranges X2 and X3 in which nonlinearity is shown between the change in radial clearance C and the change in the output voltage V of the electronic circuit 19.

[0052] In other words, in the range X2 where the radial clearance C is smaller than a predetermined value, or in the range X3 where the radial clearance C is larger than a predetermined value, the change in the output voltage V of the electronic circuit 19 becomes nonlinear, or non-linear, in response to the change in radial clearance C due to temperature changes during use. In contrast, in the intermediate range X1 where the radial clearance C is between range X2 and range X3, the change in the output voltage V of the electronic circuit 19 becomes linear, or linear, in response to the change in radial clearance C due to temperature changes during use.

[0053] Therefore, in the torque measuring device 1 of this example, the range of change △X of the radial clearance C due to temperature changes during use is regulated so that it falls within the range X1 in which the change in the output voltage V of the electronic circuit 19 changes linearly with respect to the change in radial clearance C. Specifically, the radial clearance C at room temperature is set so that the change range △X falls within the range X1 (0.2 mm to 0.8 mm in the illustrated example).

[0054] The torque measuring device 1 in this example can achieve the following effects.

[0055] In this example, the holder 8 covers the outer circumferential surface of the coil unit 7 and includes portions that protrude axially from the coil unit 7 on both sides. More specifically, in this example, the outer circumferential surface and both axial sides of the coil unit 7 are covered by the holder 8. Therefore, when assembling the coil unit 7 into a case or the like, it is possible to prevent the outer circumferential surface and axial sides of the coil unit 7 from being damaged by direct contact with surrounding objects.

[0056] Furthermore, in this example, the inner surface of the coil unit 7 is also covered by the holder 8, which prevents the inner surface of the coil unit 7 from being damaged by direct contact with surrounding objects during assembly.

[0057] Since the cylindrical portion 5 of case 2 can function as a back yoke, the torque sensor 4 does not have a separate back yoke as a standalone component. Therefore, the number of parts can be reduced accordingly.

[0058] Since the range of change △X of the radial clearance C due to temperature changes during use is restricted so that the change in the output voltage V of the electronic circuit 19 with respect to the change in radial clearance C falls within the range X1 in which the change in output voltage V of the electronic circuit 19 changes linearly, the change in the output voltage V of the electronic circuit 19 due to temperature changes during use can be easily corrected using separately detected temperature. However, when implementing the present invention, the radial clearance C can also be set so that the change range △X overlaps with range X2 or X3. In this case, the output voltage V of the electronic circuit 19 can be corrected by a correction circuit configured to take into account the nonlinearity in range X2 or X3.

[0059] [Example 2] A second example of an embodiment of the present invention will be described with reference to Figure 7.

[0060] In this example, the holder 8a constituting the torque sensor 4 covers only the outer circumferential surface and the axial sides of the coil unit 7, and does not cover the inner circumferential surface of the coil unit 7. Therefore, the volume of the holder 8a can be reduced, and the material cost of the holder 8a can be reduced. In addition, since the inner circumferential surface of the coil unit 7 can be brought closer to the outer circumferential surface of the intermediate shaft portion 6, the torque detection accuracy can be improved. The other configurations and effects are the same as in the first example. When implementing the present invention, it is also possible to adopt a configuration in which the portion of the holder 8a that covers the axial sides of the coil unit 7 is omitted.

[0061] [Example 3] A third embodiment of the present invention will be described with reference to Figure 8.

[0062] In this example, the cylindrical portion 5a constituting case 2 is provided with a circumferential groove 22 extending around its entire circumference on its inner surface. In this example, the size of the circumferential groove 22 is approximately the same as the size of the locking groove for securing the O-ring. The holder 8b constituting the torque sensor 4 is made of rubber and has a ridge 23 projecting radially outward from the axial center around its entire circumference. In this example, the torque sensor 4 is positioned axially relative to the cylindrical portion 5a by engaging the ridge 23 with the circumferential groove 22 while the outer surface of the holder 8b is fitted inside the inner surface of the cylindrical portion 5a. When inserting the torque sensor 4 into the inside of the cylindrical portion 5a through the opening of the cylindrical portion 5a, i.e., the right-hand opening in Figure 8, in order to fit the outer surface of the holder 8b inside the inner surface of the cylindrical portion 5a, the ridge 23 is elastically reduced in diameter while passing through the portion of the inner surface of the cylindrical portion 5a located between the opening and the circumferential groove 22 in the axial direction. The other components and effects are the same as in the first example.

[0063] When implementing the present invention, a modified version of the third example can be adopted, as shown in Figure 9(a) or Figure 9(b). In the modified version shown in Figure 9(a), the circumferential grooves 22 and protrusions 23 that engage with each other are positioned closer to the opening of the cylindrical portion 5a compared to the third example. In the modified version shown in Figure 9(b), the circumferential grooves 22 and protrusions 23 that engage with each other are positioned further from the opening of the cylindrical portion 5a compared to the third example. In particular, according to the modified configuration shown in Figure 9(a), when fitting the outer surface of the holder 8b into the inner surface of the cylindrical portion 5a, the distance over which the torque sensor 4 is moved axially while elastically reducing the diameter of the protrusions 23 can be shortened.

[0064] [Example 4] A fourth embodiment of the present invention will be described with reference to Figure 10.

[0065] In this example, the holder 8c has an outward-facing flange 24 that protrudes radially outward from one end on the axial side (the right side in Figure 10) along its entire circumference. In this example, with the outer surface of the holder 8c fitted inside the inner surface of the cylindrical portion 5, the outward-facing flange 24 abuts against the axial side surface 25 of the cylindrical portion 5, thereby positioning the torque sensor 4 axially relative to the cylindrical portion 5. The other configurations and effects are the same as in the first example.

[0066] [Example 5] A fifth embodiment of the present invention will be described with reference to Figure 11.

[0067] In this example, the cylindrical portion 5b of case 2 has a protrusion 26 that extends radially inward from the axial middle portion around its entire circumference. The holder 8d is made of rubber and has two outward-facing flanges 24 that extend radially outward from both ends on the axial side around its entire circumference. In this example, with the outer surface of the holder 8d fitted onto the inner surface of the protrusion 26, the protrusion 26 is clamped from both axial sides by the two outward-facing flanges 24. This positions the torque sensor 4 axially relative to the cylindrical portion 5b and prevents the torque sensor 4 from coming out axially from the inside of the cylindrical portion 5b. When fitting the holder 8d onto the inner surface of the protrusion 26, one of the two outward-facing flanges 24 is elastically reduced in diameter while passing axially through the radially inside of the protrusion 26. The other configurations and effects are the same as in the first example.

[0068] [Example 6] A sixth embodiment of the present invention will be described with reference to Figure 12.

[0069] In this example, the cylindrical portion 5c of case 2 has a stepped surface 27 on its inner circumferential surface, adjacent to the side of the cylindrical portion 5c furthest from the opening of the cylindrical portion 5c relative to the torque sensor 4, with the stepped surface 27 facing toward the torque sensor 4 in the axial direction. With the outer circumferential surface of the holder 8 fitted inside the inner circumferential surface of the cylindrical portion 5c, the torque sensor 4 is positioned in the axial direction relative to the cylindrical portion 5c by abutting the holder 8 against the stepped surface 27. The other configurations and effects are the same as in the first example.

[0070] [Case 7] A seventh embodiment of the present invention will be described with reference to Figure 13.

[0071] In this example, the cylindrical portion 5d of case 2 has an inwardly curved ring-shaped flange portion 28 at the axial end facing the opening. In this example, the torque sensor 4 is clamped from both axial sides between the stepped surface 27 of the cylindrical portion 5d and the inwardly curved flange portion 28. This positions the torque sensor 4 axially relative to the cylindrical portion 5d and prevents the torque sensor 4 from coming out axially from the inside of the cylindrical portion 5d. The inwardly curved flange portion 28 can be formed by inserting the torque sensor 4 into the inside of the cylindrical portion 5d before the inwardly curved flange portion 28 is formed, and then plastically deforming the opening end of the cylindrical portion 5d radially inward as shown by the arrow in Figure 13. The other configurations and effects are the same as in the sixth example.

[0072] The structures of each of the embodiments described above can be combined as appropriate, to the extent that no inconsistencies arise. [Explanation of symbols]

[0073] 1 Torque measuring device 2 cases 3 rotation axes 4 Torque Sensor 5, 5a, 5b, 5c, 5d Cylindrical part 6. Intermediate shaft section 7 Coil Unit 8, 8a, 8b, 8c, 8d holders 9. Detection coil 10 Flexible circuit boards 11. First split coil 12. Second split coil 13. Third-part coil 14. Fourth split coil 15 coil pieces 16 coil pieces 17 coil pieces 18 coil pieces 19 Electronic circuit 20 Oscillators 21 Lock-in amplifier 22 Circumferential groove 23 protrusion 24 Outward-facing flange 25 Axial side 26 Convex part 27 Step surface 28 Inward-facing flange

Claims

1. A magnetic metal case, a rotating shaft that is rotatably disposed inside the case and has a magnetostrictive effect part whose magnetic permeability changes in response to torque transmitted; a torque sensor disposed around the magnetostrictive effect portion and supported by the case, The torque sensor includes a coil unit formed into a cylindrical shape by a flexible substrate having a detection coil that changes voltage in response to a change in magnetic permeability of the magnetostrictive effect portion, and a holder that is made of rubber or synthetic resin, covers an outer peripheral surface of the coil unit, and has portions that protrude beyond the coil unit on both sides in the axial direction, the torque sensor is supported by the case in a state in which an outer peripheral surface of the holder is fitted into an inner peripheral surface of the case. Torque measuring device.

2. The torque measuring device according to claim 1 , wherein the holder includes a portion that covers both axial side surfaces of the coil unit.

3. 3. The torque measuring device according to claim 1, wherein the coil unit is entirely embedded in the holder.

4. 4. The torque measuring device according to claim 1, wherein a circumferential groove formed on the inner peripheral surface of the case engages with a protrusion formed on the outer peripheral surface of the holder.

5. 4. The torque measuring device according to claim 1, wherein an outward flange provided on the holder abuts against an axial side surface of the case.

6. 4. The torque measuring device according to claim 1, wherein a portion of the case is clamped from both axial sides by two outward flanges provided on the holder.

7. 4. The torque measuring device according to claim 1, wherein the holder abuts against a stepped surface facing the axial direction provided on the inner peripheral surface of the case.

8. A torque measuring device as described in any one of claims 1 to 3, wherein the holder is clamped from both sides in the axial direction between an axially facing stepped surface provided on the inner surface of the case and an inward flange portion provided on the case.

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