torque sensor

Abstract

A torque sensor capable of reducing stress on a portion provided with an electrode for a strain gauge, preventing poor contact and wire breakage is disclosed. A first structure (11) and a second structure (12) are connected by a plurality of third structures (13). A first strain sensor (14) and a second strain sensor (15) are fixed between the first structure and the second structure. The first strain sensor and the second strain sensor each have a rectangular strain gauge (14a). The strain gauge (14a) has a first end portion fixed to the first structure, an intermediate portion fixed to the second structure, and a second end portion. The second structure has a contact portion (12b) that contacts a portion between the intermediate portion and the second end portion of the strain gauge.

Description

Technical Field

[0001] Embodiments of the present invention relate to, for example, torque sensors disposed on the joints of a robotic arm. Background Technology

[0002] In a torque sensor, a first structure and a second structure are connected by a plurality of third structures, and the torque is detected by a thin-film strain sensor disposed between the first structure and the second structure (see, for example, Patent Document 1).

[0003] Thin-film strain sensors generally have an insulating film formed on the strained body, as well as a thin-film resistor and a thin-film electrode formed on the insulating film, to detect the deformation of the strained body caused by the force applied to the strained body, and the change in the resistance value of the thin-film resistor (see, for example, Patent Document 2).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2018-91813

[0007] Patent Document 2: Japanese Patent Application Publication No. 2018-132312 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] The strain gauge of the thin-film strain sensor is fixed between a first structure and a second structure. When a torque is applied between the first and second structures, the first and second structures move relative to each other, and the torque is detected by multiple thin-film resistors disposed on the portion of the strain gauge located between the first and second structures. When the fixing force or rigidity of the strain gauge relative to the first and second structures is sufficiently large, even if the torque causes relative movement between the first and second structures, the portion of the strain gauge with electrodes located outside the portion between the first and second structures will not be affected by the torque.

[0010] However, when the fixing force or rigidity is insufficient, the friction between the strained transformer and the first or second structure will cause minute stress (strain) in the part of the strained transformer where the electrodes are located. As a result, problems such as unstable electrical connections or wire breaks may occur on the electrodes.

[0011] This invention provides a torque sensor that can reduce stress on the portion of the device with electrodes, and can prevent poor contact and wire breakage.

[0012] Methods for solving problems

[0013] The torque sensor of this embodiment includes: a first structure; a second structure concentrically disposed inside the first structure; a plurality of third structures connecting the first structure and the second structure; a first strain sensor and a second strain sensor fixed between the first structure and the second structure at a position other than the third structures. The first strain sensor and the second strain sensor each have: a rectangular strain gauge having a first end, a second end, and a middle portion between the first end and the second end, the first end being fixed to the surface of the first structure, the middle portion being fixed to the surface of the second structure, and the second end being located on the surface of the second structure; a thin-film resistor disposed on the surface of the strain gauge between the first end and the middle portion; and a thin-film electrode disposed on the surface of the strain gauge located between the second end and the middle portion, electrically connected to the thin-film resistor. The torque sensor further includes: a contact portion disposed on one of the second structure and the strain gauge, contacting a portion between the middle portion and the second end of the strain gauge, or contacting a portion of the second structure. Attached Figure Description

[0014] Figure 1 This is a plan view showing the torque sensor according to the first embodiment.

[0015] Figure 2 This is a plan view showing an example of a strain sensor applicable to the first embodiment.

[0016] Figure 3 It is Figure 1 The enlarged representation of the portion represented by A is a stereoscopic image.

[0017] Figure 4 It means along Figure 3 A three-dimensional view of the cross section of line IV-IV.

[0018] Figure 5 This is a diagram that roughly illustrates the function of the first embodiment.

[0019] Figure 6 This is a perspective view showing the main parts of the torque sensor according to the second embodiment.

[0020] Figure 7 It means along Figure 6 A three-dimensional view of the cross section of line VII-VII.

[0021] Figure 8 This is a perspective view showing the main parts of the torque sensor according to the third embodiment.

[0022] Figure 9It means along Figure 8 A three-dimensional view of the cross section of the IX-IX line.

[0023] Figure 10 This is a perspective view showing the main parts of the torque sensor according to the fourth embodiment.

[0024] Figure 11 It means along Figure 10 A three-dimensional view of the cross section of the XI-XI line.

[0025] Figure 12 This is a perspective view showing the main parts of the torque sensor according to the fifth embodiment.

[0026] Figure 13 It means along Figure 12 A three-dimensional view of the cross section of line XIII-XIII.

[0027] Figure 14 This is a perspective view showing the main parts of the torque sensor according to the sixth embodiment.

[0028] Figure 15 It means along Figure 14 A three-dimensional view of the cross-section of the XV-XV line.

[0029] Figure 16 This is a perspective view showing the main parts of the torque sensor according to the seventh embodiment.

[0030] Figure 17 It means along Figure 16 A three-dimensional view of the cross section of line XVII-XVII. Detailed Implementation

[0031] The embodiments will now be described with reference to the accompanying drawings. In the drawings, the same parts are given the same reference numerals.

[0032] (First Implementation)

[0033] Figure 1 The torque sensor 10 is shown in the first embodiment.

[0034] The torque sensor 10 has a first structure 11, a second structure 12, a plurality of third structures 13 as beams, a first strain sensor 14, a second strain sensor 15, a third strain sensor 16, and a fourth strain sensor 17.

[0035] A ring-shaped second structure 12 is concentrically arranged inside the ring-shaped first structure 11, and the first structure 11 and the second structure 12 are connected by a plurality of radially arranged third structures 13.

[0036] The first structure 11, for example, receives torque, and the second structure 12, for example, outputs torque.

[0037] The first structure 11, the second structure 12, and the plurality of third structures 13 are made of metal, for example, but materials other than metal may be used if sufficient mechanical strength can be obtained for the applied torque.

[0038] A first strain sensor 14, a second strain sensor 15, a third strain sensor 16, and a fourth strain sensor 17 are connected between the first structure 11 and the second structure 12. These sensors are arranged at 90° intervals. The number of strain sensors is not limited to four; for example, it can be two or three. Since the first strain sensor 14, the second strain sensor 15, the third strain sensor 16, and the fourth strain sensor 17 have the same configuration, the configuration of the first strain sensor 14 will be described below.

[0039] Figure 2 The first strain sensor 14 is magnified and shown.

[0040] The first strain sensor 14 includes: a strain gauge 14a; thin-film resistive elements 14b and 14c; multiple thin-film wirings 14d, 14e, 14f and 14g; and thin-film electrodes 14h, 14i and 14j.

[0041] Strain 14a may be made of, for example, a rectangular elastic body (metal) such as stainless steel (SUS). The shape and material of strain 14a are not limited to these, as long as they are materials that can be fused or brazed, such as ceramics (e.g., zirconium oxide with a coefficient of linear expansion close to that of SUS), as described later.

[0042] The strain gauge 14a includes: thin-film resistors 14b and 14c; thin-film wiring 14d, 14e, and 14f; thin-film electrodes 14h, 14i, and 14j; first fixing portions C1 and C2; second fixing portions C3 and C4; a transmission portion 14k; and an electrode placement region 14l. The number of thin-film resistors is not limited to two; for example, it can be four. The number of thin-film resistors and the number of strain sensors can vary depending on the configuration of the bridge circuit composed of resistors.

[0043] The first fixing parts C1 and C2 are provided at the first end in the length direction of the strained body 14a and at both ends in the short side direction of the strained body 14a. The second fixing parts C3 and C4 are provided at approximately the middle part in the length direction of the strained body 14a and at both ends in the short side direction of the strained body 14a.

[0044] The transfer section 14k is disposed between the first fixing sections C1 and C2 and the second fixing sections C3 and C4, and the electrode configuration area 14l is disposed between the second end of the strain 14a in the length direction and the second fixing sections C3 and C4.

[0045] The first fixing parts C1 and C2 are fixed to the first structure 11 and are the parts that transmit force between the first structure 11 and the strain gauge 14a. The second fixing parts C3 and C4 are fixed to the second structure 12 of the torque sensor and are the parts that transmit force between the second structure 12 and the strain gauge 14a.

[0046] The fixing methods for the first fixing parts C1, C2 and the first structure 11, and the fixing methods for the second fixing parts C3, C4 and the second structure 12, are, for example, fusion welding or brazing.

[0047] Figure 1 , Figure 2 The circles representing the first fixing parts C1 and C2 and the second fixing parts C3 and C4 indicate the engagement positions (engagement areas). Figure 2 In the diagram, the dashed line (straight line) connecting the two circles simply represents the range of the transmission section 14k.

[0048] The transmission part 14k is the part that transmits force between the first fixing parts C1 and C2 and the second fixing parts C3 and C4. The transmission part 14k is the area that deforms according to the force received from the first structure 11 and the second structure 12.

[0049] Thin film resistors 14b and 14c are disposed near the first fixing parts C1 and C2 within the transmission part 14k, and convert the deformation of the transmission part 14k into an electrical signal.

[0050] Thin film electrodes 14h, 14i, and 14j are disposed in an electrode configuration region 14l, other than the first fixing portions C1 and C2, the second fixing portions C3 and C4, and the transfer portion 14k, near the other end of the strain 14a.

[0051] Thin film electrodes 14h and 14i are connected to thin film resistor 14b via thin film wiring 14d and 14e, and thin film electrodes 14i and 14j are connected to thin film resistor 14c via thin film wiring 14f and 14g. Thin film electrode 14i is a common electrode for thin film resistors 14b and 14c.

[0052] It should be noted that the number of thin-film resistors, the number of thin-film electrodes, and the number of wiring connecting the thin-film resistors and thin-film electrodes are not limited to these and can be changed.

[0053] Figure 3 , Figure 4 Will Figure 1 The A part is enlarged.

[0054] The first structure 11 has a first recess 11a for receiving the strain gauge 14a, and the second structure 12 has a second recess 12a for receiving the strain gauge 14a. The first recess 11a has a first bottom surface 11b, and the second recess 12a has a second bottom surface 12b at the same height as the first bottom surface 11b. The first recess 11a and the second recess 12a are not essential components and can be omitted.

[0055] The variant 14a engages with the first bottom surface 11b of the first structure 11 at the first fixing parts C1 and C2, and engages with the second bottom surface 12b of the second structure 12 at the second fixing parts C3 and C4.

[0056] The second recess 12a of the second structure 12 has a third bottom surface 12c and a stepped portion 12d. The third bottom surface 12c is lower than the second bottom surface 12b and corresponds to the electrode arrangement area 14l of the strain gauge 14a. The stepped portion 12d is located between the second bottom surface 12b and the third bottom surface 12c, which are contact portions with the strain gauge 14a, and this position is near the second fixing portions C3 and C4.

[0057] A gap exists between the back surface of strain gauge 14a and the third bottom surface 12c, and the back surface of the electrode configuration region 14l of strain gauge 14a is away from the third bottom surface 12c. The gap is, for example, less than 0.05 mm. Therefore, no frictional force is generated between the back surface of the electrode configuration region 14l of strain gauge 14a and the third bottom surface 12c.

[0058] Figure 5 This diagram illustrates the function of the first embodiment, showing the situation of force transmission between the first structure 11 and the second structure 12.

[0059] As shown by the arrows in the attached figures, the first structure 11 and the second structure 12 move in opposite directions. When the fixing force or rigidity of the first fixing parts C1, C2 and the second fixing parts C3, C4 is sufficient, the transmission part 14k of the strain gauge 14a deforms, and strain is detected by the thin-film resistors 14b, 14c. At this time, since there is a gap between the back surface of the electrode arrangement area 14l of the strain gauge 14a and the third bottom surface 12c, no frictional force is generated between them, and the electrode arrangement area 14l is not subjected to force from the second structure 12. Therefore, even if the fixing force or rigidity of the second fixing parts C3, C4 is weak within the allowable range, the electrode arrangement area 14l will not deform. Therefore, the force from the second structure 12 will not be transmitted to the thin-film electrodes 14h, 14i, 14j arranged in the electrode arrangement area 14l, or the wires connected to the thin-film electrodes 14h, 14i, 14j, thereby preventing them from breaking.

[0060] On the other hand, when the entire back surface of the electrode arrangement region 14l is in contact with the surface of the second structure 12 as in the past, the friction between the electrode arrangement region 14l and the second structure 12 will cause the electrode arrangement region 14l to be subjected to a force from the second structure 12. Therefore, if the fixing force or rigidity of the second fixing parts C3 and C4 is weak within the allowable range, such as Figure 5 As shown by the dashed lines, the electrode configuration area 14l will deform. Therefore, the thin film electrodes 14h, 14i, 14j configured in the electrode configuration area 14l, or the wires connected to the thin film electrodes 14h, 14i, 14j, may be damaged by forces.

[0061] It should be noted that the gap between the back surface of strain gauge 14a and the third bottom surface 12c is extremely narrow, for example, less than 0.05 mm. Therefore, when thin film electrodes 14h, 14i, and 14j are coupled with wires (not shown), strain gauge 14a can be bent to abut against the third bottom surface 12c. Thus, the wires can be coupled to the thin film electrodes 14h, 14i, and 14j with sufficient strength.

[0062] (Effects of the first implementation method)

[0063] According to the first embodiment described above, the second structure 12 has a second bottom surface 12b as a contact portion. The strain gauge 14a contacts the second bottom surface 12b between the second fixing portions C3 and C4 and the step portion 12d. A gap exists between the back surface of the electrode placement area 14l of the strain gauge 14a and the third bottom surface 12c. Therefore, in the event of a force transmission between the first structure 11 and the second structure 12, the electrode placement area 14l of the strain gauge 14a will not be subjected to force from the second structure 12. Thus, even if the fixing force or rigidity of the second fixing portions C3 and C4 is weak within the allowable range, deformation of the electrode placement area 14l can be prevented, thereby preventing damage to the thin film electrodes 14h, 14i, and 14j disposed in the electrode placement area 14l.

[0064] (Second Implementation)

[0065] Figure 6 , Figure 7 This indicates the second embodiment. In the first embodiment, the second structure 12 has a stepped portion 12d that serves as the boundary between it and the contact portion, and the electrode arrangement region 14l of the strain 14a is located away from the third bottom surface 12c of the second structure 12.

[0066] In contrast, in the second embodiment, the second structure 12 also has a third recess 21 within the second recess 12a, and the two second bottom surfaces 12b of the edge of the third recess 21 located in the length direction of the strain 14a function as contact portions.

[0067] Specifically, the third recess 21 is disposed corresponding to the central portion of the electrode arrangement region 14l of the strain gauge 14a. Therefore, most of the electrode arrangement region 14l is opposite to the third recess 21 and does not contact the second bottom surface 12b. The vicinity of the second fixing portions C3 and C4 of the strain gauge 14a contacts one of the two bottom surfaces 12b that are divided by the third recess 21, and the second end of the strain gauge 14a contacts the other of the two bottom surfaces 12b that are divided by the third recess 21.

[0068] In the above configuration, the first structure 11 and the second structure 12 move in opposite directions. When the fixing force or rigidity of the second fixing portions C3 and C4 is weak within the allowable range, a small amount of friction will be generated between the portion of the strain gauge 14a between the second fixing portions C3 and C4 and the third recess 21, and between the back surface of the second end of the strain gauge 14a and the second bottom surface 12b. However, most of the electrode arrangement region 14l will not generate friction and will not be subjected to force from the second structure 12, so the electrode arrangement region 14l will hardly deform. Therefore, the force from the second structure 12 will not be transmitted to the thin film electrodes 14h, 14i, and 14j arranged in the electrode arrangement region 14l, or the unshown wires connected to the thin film electrodes 14h, 14i, and 14j, thereby preventing them from breaking.

[0069] Furthermore, since the second end of the strain gauge 14a is disposed on the second bottom surface 12b, the strain gauge 14a can be sufficiently held in place when the thin film electrodes 14h, 14i, and 14j are coupled with wires (not shown). Therefore, the wires can be coupled with the thin film electrodes 14h, 14i, and 14j with sufficient strength.

[0070] (Effects of the second implementation method)

[0071] According to the second embodiment, the same effect as the first embodiment can also be obtained. Moreover, according to the second embodiment, since the second end of the strain gauge 14a is disposed on the second bottom surface 12b of the second recess 12a, the strain gauge 14a can be stably maintained.

[0072] (Third Implementation)

[0073] Figure 8 , Figure 9 This represents the third embodiment. In the second embodiment, the second end of the strain 14a is disposed on the second bottom surface 12b of the second recess 12a.

[0074] In contrast, in the third embodiment, the second structure 12 has a groove 31 along the length direction of the strain 14a, and the two sides of the groove 31 function as contact portions that contact the two sides of the strain 14a along the length direction.

[0075] Specifically, a groove 31 is formed on the second bottom surface of the second structure 12, extending radially from near the second fixing portions C3 and C4. The width of the groove 31 is narrower than the width of the strain gauge 14a. Therefore, the second bottom surfaces 12b on both sides of the strain gauge 14a along its length contact the second bottom surfaces 12b on both sides of the groove 31, while most of the strain gauge 14a is opposite to the groove 31 and does not contact the second bottom surfaces 12b.

[0076] In the above configuration, the first structure 11 and the second structure 12 move in opposite directions. When the fixing force or rigidity of the second fixing parts C3 and C4 is weak within the allowable range, a small amount of friction will be generated between the portion of the strain gauge 14a between the second fixing parts C3 and C4 and the groove 31, as well as between the back surfaces and the second bottom surface 12b on both sides of the strain gauge 14a. However, most of the electrode arrangement area 14l will not generate friction, and therefore will not be subjected to force from the second structure 12, and the electrode arrangement area 14l will hardly deform. Therefore, the force from the second structure 12 will not be transmitted to the thin film electrodes 14h, 14i, and 14j arranged in the electrode arrangement area 14l, or the wires connected to the thin film electrodes 14h, 14i, and 14j, thereby preventing them from breaking.

[0077] Furthermore, since the strain gauge 14a is disposed on both sides of the second bottom surface 12b, the strain gauge 14a can be sufficiently held in place when the thin film electrodes 14h, 14i, and 14j are coupled with wires (not shown). Therefore, the wires can be coupled with the thin film electrodes 14h, 14i, and 14j with sufficient strength.

[0078] (Effects of the third implementation method)

[0079] According to the third embodiment, the same effect as the first embodiment can also be obtained. Moreover, according to the third embodiment, since the two sides of the strain gauge 14a are disposed on the second bottom surface 12b, the strain gauge 14a can be stably maintained.

[0080] (Fourth Implementation)

[0081] Figure 10 , Figure 11 This represents the fourth embodiment. In the third embodiment, the two sides of strain 14a are disposed on the second bottom surface 12b.

[0082] In contrast, the fourth embodiment is a variation of the first embodiment, having a first protrusion 41 as a contact portion that makes point contact with the vicinity of the second end of the strain 14a.

[0083] Specifically, a first protrusion 41 is provided on the third bottom surface 12c formed by the stepped portion 12d. The first protrusion 41 is, for example, a locating pin, but is not limited thereto. The first end of the first protrusion 41 is inserted into the second structure 12, and the surface of the second end is, for example, machined into a spherical shape to make point contact with the back surface of the electrode arrangement region 14l of the strain gauge 14a. The position of the point contact corresponds, for example, to the position of the electrode arrangement region 14l where the thin film electrode 14i is arranged.

[0084] In the above configuration, the first structure 11 and the second structure 12 move in opposite directions. When the fixing force or rigidity of the second fixing portions C3 and C4 is relatively weak within the allowable range, a small amount of friction will be generated between the portion of the strained body 14a between the second fixing portions C3 and C4 and the step portion 12d, and between the strained body 14a and the first protrusion 41 that makes point contact with the back side of the strained body 14a. However, most of the electrode arrangement region 14l will not generate friction, and therefore will not be subjected to force from the second structure 12, and the electrode arrangement region 14l will hardly deform. Therefore, the force from the second structure 12 will not be transmitted to the thin film electrodes 14h, 14i, and 14j arranged in the electrode arrangement region 14l, or the wires connected to the thin film electrodes 14h, 14i, and 14j, thereby preventing them from breaking.

[0085] Furthermore, since strain gauge 14a is supported by the first protrusion 41, strain gauge 14a can be adequately held in place when thin film electrodes 14h, 14i, and 14j are coupled with wires (not shown). Therefore, the wires can be coupled with the thin film electrodes 14h, 14i, and 14j with sufficient strength.

[0086] (Effects of the fourth implementation method)

[0087] According to the fourth embodiment, the same effect as the first embodiment can also be obtained. Moreover, according to the fourth embodiment, since the strain 14a is supported by the first protrusion 41, the strain 14a can be stably maintained.

[0088] (Fifth Implementation)

[0089] Figure 12 , Figure 13 This represents the fifth embodiment. In the fourth embodiment, the back surface of strain 14a contacts the first protrusion 41 at point.

[0090] In contrast, the fifth embodiment has a second protrusion 51, which serves as a contact portion that makes line contact with the vicinity of the second end of the strain 14a.

[0091] Specifically, the second protrusion 51 is, for example, a cylinder. A groove 12e is provided on the third bottom surface 12c formed by the step portion 12d of the second structure 12, in a direction intersecting the longitudinal direction of the strain gauge 14a. The second protrusion 51 is housed within the groove 12e in the direction where the axis of the cylinder intersects the longitudinal direction of the strain gauge 14a. The depth of the groove 12e is approximately equal to the radius of the cylinder, and approximately half of the second protrusion 51 protrudes from the groove 12e, making line contact with the back surface of the electrode arrangement region 14l of the strain gauge 14a. The location of the line contact is, for example, along the positions in the electrode arrangement region 14l where the thin film electrodes 14h, 14i, and 14j are arranged.

[0092] In the above configuration, the first structure 11 and the second structure 12 move in opposite directions. When the fixing force or rigidity of the second fixing portions C3 and C4 is relatively weak within the allowable range, a small amount of friction will be generated between the strained body 14a and the portion between the second fixing portions C3 and C4 and the step portion 12d, and between the strained body 14a and the second protrusion 51 that contacts the back surface of the strained body 14a. However, most of the electrode arrangement region 14l will not generate friction, and therefore will not be subjected to force from the second structure 12, and the electrode arrangement region 14l will hardly deform. Therefore, the force from the second structure 12 will not be transmitted to the thin film electrodes 14h, 14i, and 14j arranged in the electrode arrangement region 14l, or the wires connected to the thin film electrodes 14h, 14i, and 14j, thereby preventing them from breaking.

[0093] Furthermore, since strain gauge 14a is supported by the second protrusion 51, strain gauge 14a can be adequately held in place when thin film electrodes 14h, 14i, and 14j are coupled with wires (not shown). Therefore, the wires can be coupled with the thin film electrodes 14h, 14i, and 14j with sufficient strength.

[0094] (Effects of the fifth implementation method)

[0095] According to the fifth embodiment, the same effect as the first embodiment can also be obtained. Moreover, according to the fifth embodiment, since the strain 14a is supported by the second protrusion 51 that is in contact with the line of the strain 14a, the strain 14a can be held more stably.

[0096] (Sixth Implementation Method)

[0097] Figure 14 , Figure 15 This indicates the sixth embodiment. In the fifth embodiment, the second protrusion 51 is cylindrical in shape.

[0098] In contrast, the sixth embodiment has a third protrusion 61 formed of a material with a low coefficient of friction near the second end of the strain 14a, serving as a contact portion. The third protrusion 61 is shaped as a quadrangular prism.

[0099] A third protrusion 61, formed of a quadrangular prism of low friction coefficient, is housed within a groove 12e in a direction where its axis intersects the longitudinal direction of the strain gauge 14a. The depth of the groove 12e is approximately half the length of one side of the quadrangular prism, and approximately half of the third protrusion 61 protrudes from the groove 12e, making surface contact with the back surface of the electrode arrangement region 14l of the strain gauge 14a. The surface contact location is, for example, along the positions in the electrode arrangement region 14l where thin film electrodes 14h, 14i, and 14j are arranged.

[0100] Materials with low coefficients of friction can be used, for example, fluoropolymers (polytetrafluoroethylene (PTFE)), nylon resins (polyamide (PA)), etc.; or metals subjected to electroless nickel plating, metals coated with diamond-like carbon (DLC), and oil-impregnated sintered metals. Oil-impregnated sintered metals are, for example, porous sintered bodies composed of copper-based metals containing graphite powder that contain oil.

[0101] In the above configuration, the first structure 11 and the second structure 12 move in opposite directions. When the fixing force or rigidity of the second fixing parts C3 and C4 is weak within the allowable range, a small amount of friction will be generated between the portion of the strain gauge 14a between the second fixing parts C3 and C4 and the groove 31, and between the strain gauge 14a and the third protrusion 61 with a low coefficient of friction that makes surface contact with the back surface of the strain gauge 14a. However, most of the electrode arrangement region 14l will not generate friction, and therefore will not be subjected to force from the second structure 12, and the electrode arrangement region 14l will hardly deform. Therefore, the force from the second structure 12 will not be transmitted to the thin film electrodes 14h, 14i, and 14j arranged in the electrode arrangement region 14l, or the wires connected to the thin film electrodes 14h, 14i, and 14j, thereby preventing them from breaking.

[0102] Furthermore, since strain gauge 14a is supported by the third protrusion 61 of the surface contact, strain gauge 14a can be adequately held in place when thin film electrodes 14h, 14i, and 14j are coupled with wires (not shown). Therefore, the wires can be coupled with thin film electrodes 14h, 14i, and 14j with sufficient strength.

[0103] (Effects of the sixth implementation method)

[0104] According to the sixth embodiment, the same effect as the first embodiment can also be obtained. Moreover, according to the sixth embodiment, since the strain 14a is supported by the third protrusion 61 that is in contact with the surface of the strain 14a, the strain 14a can be held more stably.

[0105] (Seventh Implementation)

[0106] Figure 16 , Figure 17This refers to the seventh embodiment. In order to reduce the frictional force between the strain 14a and the second structure 12, the structure of the second structure 12 side was improved in the first to sixth embodiments described above.

[0107] In contrast, the seventh embodiment does not modify the second structure 12, but modifies the configuration of the variant 14a.

[0108] Specifically, the electrode configuration region 14l of strain gauge 14a is configured to contact the flat second bottom surface 12b, and strain gauge 14a has a constriction portion 71 on a portion of the electrode configuration region 14l. The constriction portion 71 is, for example, provided between the second fixing portions C3, C4 and the thin-film electrodes 14h, 14i, 14j. The constriction portion 71 has a narrower area than other portions of the electrode configuration region 14l. Therefore, the contact area between the electrode configuration region 14l and the second bottom surface 12b of the second structure 12 is reduced.

[0109] In the above configuration, the first structure 11 and the second structure 12 move in opposite directions. When the fixing force or rigidity of the second fixing parts C3 and C4 is weak within the allowable range, a small amount of friction will be generated between the electrode arrangement area 14l of the strain gauge 14a and the second bottom surface 12b of the second structure 12. However, the contraction part 71 reduces the friction compared to the case without the contraction part 71. Moreover, since the width of the contraction part 71 is narrower than the width of other parts of the electrode arrangement area 14l, this part can deform. Therefore, the friction will deform the contraction part 71, thereby preventing the electrode arrangement area 14l from deforming. Therefore, the force from the second structure 12 will not be transmitted to the thin film electrodes 14h, 14i, and 14j arranged in the electrode arrangement area 14l, or the wires connected to the thin film electrodes 14h, 14i, and 14j, thereby preventing them from breaking.

[0110] Furthermore, since the electrode configuration region 14l is supported by the second bottom surface 12b, the electrode configuration region 14l can be sufficiently maintained when the thin film electrodes 14h, 14i, and 14j are coupled with wires (not shown). Therefore, the wires can be coupled with the thin film electrodes 14h, 14i, and 14j with sufficient strength.

[0111] (Effects of the seventh implementation method)

[0112] According to the seventh embodiment, the same effects as in the first embodiment can also be obtained. Furthermore, according to the seventh embodiment, the deformation of the contraction portion 71 prevents forces from the second structure 12 from being transmitted to the thin-film electrodes 14h, 14i, 14j disposed in the electrode arrangement region 14l, or to the wires connected to the thin-film electrodes 14h, 14i, 14j. Therefore, damage to them can be further prevented.

[0113] Furthermore, this invention is not directly limited to the above-described embodiments. During implementation, the constituent elements can be modified and made more specific without departing from its essence. Additionally, various inventions can be formed by appropriately combining multiple constituent elements disclosed in the above-described embodiments. For example, several constituent elements can be deleted from all the constituent elements shown in the embodiments. Furthermore, constituent elements from different embodiments can be appropriately combined.

Claims

1. A torque sensor, comprising: First structure; The second structure is arranged concentrically with the first structure inside the first structure; Multiple third structures, which connect the first structure and the second structure; and, A first strain sensor and a second strain sensor are fixed between the first structure and the second structure at a location other than the third structure. The first strain sensor and the second strain sensor respectively have: A rectangular strain having a first end, a second end, and a middle portion between the first end and the second end, the first end being fixed to the surface of the first structure, the middle portion being fixed to the surface of the second structure, and the second end being located on the surface of the second structure; A thin-film resistor disposed on a surface between the first end and the intermediate portion of the strain body; and A thin-film electrode, disposed on the surface of the strainer located between the second end and the middle portion of the strainer, is electrically connected to the thin-film resistor. The second structure has a protrusion at a position corresponding to the second end of the strained body, and the protrusion makes point contact with the strained body.

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