Torque Sensor

Abstract

To provide a torque sensor capable of suppressing a decrease in detection accuracy.SOLUTION: A torque sensor 1 includes: a first area 2 having a first surface 21 and a second surface 22 opposite the first surface 21; a second area 3 arranged around the first area 2; a plurality of beams connecting the first area 2 to the second area 3; and a detector configured to be able to detect torque applied between the first area 2 and the second area 3, and arranged on the first surface 21 of the first area 2. The detector has an insulation film 51 layered on the first area 2, and strain gauges layered on the insulation film 51 and configured to be deformable in response to the torque. In the second surface 22 of the first area 2, screw holes 23 which do not penetrate to the first surface 21 and into which fasteners are screwed are formed. A thickness H between the bottom surface of each of the screw holes 23 and the first surface 21 is equal to or more than one fourth of a diameter M of each of the screw holes 23.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present invention relates to a torque sensor. [Background technology]

[0002] 2. Description of the Related Art Conventionally, torque sensors for use in joints of robots and the like are known (for example, Patent Document 1).

[0003] In Patent Document 1, an insulating film is laminated on a first region that is disposed inside a second region, and a strain gauge is laminated on the insulating film. This makes it unnecessary to provide an insulating film on a beam portion that connects the first region and the second region, which facilitates the process of forming the insulating film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2021 / 117855 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, when a screw hole portion is provided in the first region where the strain gauge is arranged and a fastener such as a bolt is screwed into the screw hole portion, the strain gauge detects the strain caused by the screwing of the fastener, resulting in a problem in that the detection accuracy of the torque applied to the strain gauge is reduced.

[0006] An object of the present invention is to provide a torque sensor capable of suppressing a decrease in detection accuracy. [Means for solving the problem]

[0007] The torque sensor of the present invention comprises a first region having a first surface and a second surface opposite to the first surface, a second region arranged around the first region or inside the first region, a plurality of beam portions connecting the first region and the second region, and a detection portion arranged on the first surface of the first region and configured to be able to detect a torque acting between the first region and the second region, the detection portion having an insulating film laminated on the first region and a strain gauge laminated on the insulating film and configured to be deformable in response to the torque, the second surface of the first region has a screw hole portion formed therein that does not penetrate the first surface and into which a fastener is screwed, and a thickness between a bottom surface of the screw hole portion and the first surface is equal to or greater than ¼ of a diameter of the screw hole portion.

[0008] In the present invention, a screw hole portion is formed on the second surface of the first region, which does not penetrate to the first surface on which the detection unit is arranged, and into which the fastener is screwed. The thickness between the bottom surface of the screw hole portion and the first surface is set to be ¼ or more of the diameter of the screw hole portion. This makes it possible to prevent distortion caused by the fastener being screwed into the screw hole portion from being transmitted to the detection unit when the fastener is screwed into the screw hole portion. Therefore, even if the screw hole portion is provided in the first region, it is possible to suppress a decrease in the torque detection accuracy.

[0009] In the torque sensor of the present invention, it is preferable that a thickness between a bottom surface of the screw hole portion and the first surface is equal to or greater than half a diameter of the screw hole portion. In this configuration, the thickness between the bottom surface of the screw hole portion and the first surface is at least half the diameter of the screw hole portion, so that even if the screw hole portion is provided in the first region, a decrease in torque detection accuracy can be more reliably prevented.

[0010] The torque sensor of the present invention comprises a first region having a first surface and a second surface opposite to the first surface, a second region arranged around the first region or inside the first region, a plurality of beam portions connecting the first region and the second region, and a detection portion arranged on the first surface of the first region and configured to be able to detect a torque acting between the first region and the second region, the detection portion having an insulating film laminated on the first region and a strain gauge laminated on the insulating film and configured to be deformable in response to the torque, the second surface of the first region has a screw hole portion into which a fastener is screwed, and the distance between the strain gauge and an outer periphery of the screw hole portion in the extension direction of the first surface is equal to or greater than half the diameter of the screw hole portion.

[0011] In the present invention, a screw hole into which a fastener is screwed is formed on the second surface of the first region. The distance between the strain gauge and the outer periphery of the screw hole in the direction in which the first surface extends is set to be equal to or greater than 1 / 2 the diameter of the screw hole. This makes it possible to make it difficult for strain caused by the fastener being screwed into the screw hole to be transmitted to the detection unit when the fastener is screwed into the screw hole. Therefore, even if a screw hole is provided in the first region, it is possible to suppress a decrease in torque detection accuracy.

[0012] In the torque sensor of the present invention, it is preferable that the distance between the strain gauge and an outer periphery of the screw hole portion in the extending direction of the first surface is equal to or greater than a diameter of the screw hole portion. In this configuration, the distance between the strain gauge and the outer periphery of the screw hole portion in the direction in which the first surface extends is greater than or equal to the diameter of the screw hole portion, so that even if a screw hole portion is provided in the first region, a decrease in torque detection accuracy can be more reliably prevented.

[0013] In the torque sensor of the present invention, the number of the screw holes is an integer multiple of the number of the beam portions, and the plurality of the screw holes are When viewed from the center point of the first region, the beam portions are disposed at positions corresponding to the beam portions and at equal intervals on a virtual circle having the center point as a center. It is preferred. In this configuration, the multiple screw hole portions are arranged symmetrically relative to the beam portion when viewed in a plan view, so that when the fastener is screwed into the screw hole portions, uneven distortion caused by the screwing of the fastener can be suppressed. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a plan view showing an outline of a torque sensor according to a first embodiment of the present invention. [Diagram 2] FIG. 2 is a plan view showing an outline of the torque sensor as viewed from the opposite side to FIG. [Diagram 3] FIG. 2 is a schematic cross-sectional view taken along line III-III in FIG. [Figure 4] FIG. 13 is a graph showing the relationship between H / M and the zero point change rate. [Diagram 5] FIG. 11 is a plan view showing an outline of a torque sensor according to a second embodiment. [Figure 6] FIG. 6 is a plan view showing an outline of the torque sensor as viewed from the opposite side to that in FIG. 5. [Figure 7] 7 is a schematic cross-sectional view taken along line VII-VII in FIG. 5. [Figure 8] FIG. 13 is a graph showing the relationship between L / M and the zero point change rate. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] [First embodiment] A torque sensor 1 according to a first embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a plan view showing an outline of the torque sensor 1 of this embodiment, Fig. 2 is a plan view showing an outline of the torque sensor 1 seen from the opposite side to that of Fig. 1, and Fig. 3 is a sectional view showing an outline when cut along line III-III in Fig. 1. The torque sensor 1 of this embodiment is mounted on a joint portion of a robot or the like, and is configured to be able to detect torque acting between a first region 2 and a second region 3. As shown in FIGS. 1 to 3, the torque sensor 1 includes a first region 2, a second region 3, a beam portion 4, and a detection portion 5. The first region 2, the second region 3, a beam portion 4, and a detection portion 5 are arranged in a direction perpendicular to the axis of the sensor.

[0016] [First area 2] The first region 2 is made of metal and formed in a circular ring shape. In this embodiment, the first region 2 is connected to an output shaft of a driving device such as a motor. As a result, the first region 2 is configured to transmit torque generated by the driving device such as a motor. The first area 2 has a first surface 21 and a second surface 22 opposite to the first surface 21. The detection unit 5 is disposed on the first surface 21 of the first area 2. Furthermore, on the first surface 21 of the first region 2, conductors, electrodes, etc. (not shown) are arranged.

[0017] Further, the second surface 22 of the first region 2 is formed with a screw hole portion 23 that does not penetrate the first surface 21. In this embodiment, four screw hole portions 23 are formed, namely, a first screw hole portion 231, a second screw hole portion 232, a third screw hole portion 233, and a fourth screw hole portion 234. A fastener such as a bolt can be screwed into each of the screw hole portions 231, 232, 233, and 234. That is, the inner circumferential surfaces of the screw hole portions 231, 232, 233, and 234 are threaded. As a result, the torque sensor 1 can be fixed to a fixing member or the like by screwing a fastener such as a bolt into the screw hole portion 23.

[0018] In this embodiment, the screw holes 231, 232, 233, and 234 are disposed symmetrically with respect to the beam portion 4 in a plan view. Specifically, when viewed from the center O, the first screw hole portion 231 is disposed at a position corresponding to the first beam portion 41 described later, the second screw hole portion 232 is disposed at a position corresponding to the second beam portion 42 described later, the third screw hole portion 233 is disposed at a position corresponding to the third beam portion 43 described later, and the fourth screw hole portion 234 is disposed at a position corresponding to the fourth beam portion 44 described later. Furthermore, in this embodiment, the respective screw holes 231, 232, 233, 234 are disposed at equal intervals on an imaginary circle C having the center O.

[0019] [Second area 3] The second region 3 is made of metal, has an annular shape, and is disposed around the first region 2 in a plan view. In this embodiment, the second region 3 is disposed concentrically with the first region 2. The second region 3 is connected to the first region 2 by a beam portion 4. The second region 3 is fixed to a fixing member or the like by a fastener such as a bolt.

[0020] The beam portion 4 is disposed between the outer periphery of the first region 2 and the inner periphery of the second region 3, and is a member that connects the first region 2 and the second region 3. Therefore, when torque generated by the driving device is transmitted to the first region 2, the beam portion 4 transmits the torque to the second region 3. Here, in this embodiment, since the second region 3 is fixed to a fixed member, the torque between the first region 2 and the second region 3 acts on the beam portion 4. Therefore, the beam portion 4 is a location where distortion due to the torque is likely to occur. In this embodiment, the beam portion 4 is provided by a metal plate member integral with the first region 2 and the second region 3. That is, in this embodiment, the first region 2, the second region 3, and the beam portion 4 are formed by processing a metal plate member. The metal plate member has a thickness that allows it to bend and flex.

[0021] In this embodiment, as described above, the beam portion 4 has four beam portions: the first beam portion 41, the second beam portion 42, the third beam portion 43, and the fourth beam portion 44. Each of the beam portions 41, 42, 43, and 44 is disposed at a position facing the pair of beam portions 41, 42, 43, and 44 with the first region 2 in between. Specifically, the pair of the first beam portion 41 and the second beam portion 42 are disposed at positions facing each other with the first region 2 in between, that is, on the same diameter line of the circle that constitutes the first region 2. Also, the pair of the third beam portion 43 and the fourth beam portion 44 are disposed at positions facing each other with the first region 2 in between, that is, on the same diameter line of the circle that constitutes the first region 2.

[0022] In this embodiment, each of the beams 41, 42, 43, 44 is formed so that the end portion on the first region 2 side and the end portion on the second region 3 side are wider than the central portion. As a result, when torque is applied to each of the beams 41, 42, 43, 44, the end portion where stress is likely to concentrate is wider, and therefore, it is possible to prevent each of the beams 41, 42, 43, 44 from being damaged by the torque.

[0023] [Detection unit 5] The detection unit 5 has an insulating film 51 and a strain gauge 52 . The insulating film 51 is laminated so as to cover substantially the entire surface of the first region 2, and serves to insulate the first region 2 from the strain gauge 52 and conductors (not shown), etc. In this embodiment, the insulating film 51 is composed of a plurality of layers. Specifically, the insulating film 51 is composed of a layer formed of an insulating glass material, a layer formed of a resin, etc. This makes it easier to adjust the thickness of the insulating film 51 in this embodiment.

[0024] The strain gauges 52 are laminated on the insulating film 51, and are provided at positions corresponding to the beam portions 41, 42, 43, and 44. The strain gauges 52 include four strain gauges: a first strain gauge 521, a second strain gauge 522, a third strain gauge 523, and a fourth strain gauge 524. Each of the strain gauges 521, 522, 523, and 524 is configured to include two resistors R1 and R2. In this embodiment, the resistors R1 and R2 are formed by printing.

[0025] Here, in this embodiment, the resistors R1 and R2 constituting each of the strain gauges 521, 522, 523, and 524 are arranged at positions corresponding to the beams 41, 42, 43, and 44, respectively. Specifically, the resistors R1 and R2 are arranged at positions in the first region 2 where they are connected to the ends of the beams 41, 42, 43, and 44. As a result, when a torque acts between the first region 2 and the second region 3 and the torque causes distortion in the beams 41, 42, 43, and 44, the distortion is transmitted to the resistors R1 and R2, and the resistors R1 and R2 are deformed by the distortion. That is, the resistors R1 and R2 are configured to be deformable according to the torque acting between the first region 2 and the second region 3.

[0026] The resistors R1 and R2 are electrically connected to the circuit board via conductors and electrodes (not shown) to form a bridge circuit. Specifically, the resistor R1 is connected to a power supply potential VDD, and the resistor R2 is connected to a ground potential or GND. As a result, the strain gauges 521, 522, 523, and 524 are connected in series between the power supply potential VDD and the ground potential or GND. In this embodiment, the torque sensor 1 is configured to detect the amount of change in voltage between the resistors R1 and R2 due to deformation of the resistors R1 and R2 in response to the torque, thereby being capable of detecting the torque acting between the first region 2 and the second region 3. Note that a method for detecting torque based on a change in voltage between the resistors R1 and R2 is well known, and therefore a detailed description thereof will be omitted.

[0027] [Method of forming the screw hole 23 and torque detection accuracy] Next, a method for forming the screw hole 23 and the torque detection accuracy will be described. As described above, the screw holes 231 , 232 , 233 , 234 that do not penetrate through to the first surface 21 are formed in the second surface 22 of the first region 2 . At this time, the screw holes 231, 232, 233, 234 are formed so that the thickness H between the bottom surface of the screw holes 231, 232, 233, 234 and the first surface 21 is ¼ or more, preferably ½ or more, of the diameter M of the screw holes 231, 232, 233, 234.

[0028] 4 is a diagram showing the relationship between the ratio of the diameter M of the screw hole portions 231, 232, 233, 234 to the thickness H between the bottom surfaces of the screw hole portions 231, 232, 233, 234 and the first surface 21, and the zero point change rate of the strain gauge 52. Note that FIG. 4 shows the zero point change rate when the judgment criterion is set to 1. FIG. 4 shows test results of the zero point change rate when screw holes 231, 232, 233, and 234 having a diameter of about 5 mm are provided and bolts are screwed into the screw holes 231, 232, 233, and 234. 4, it is suggested that when H / M is smaller than 0.25 (1 / 4), the zero point change rate of strain gauge 52 exceeds the judgment criterion when fasteners such as bolts are screwed into screw holes 231, 232, 233, and 234. On the other hand, it is suggested that by setting H / M to 0.25 (1 / 4) or more, the zero point change rate can be suppressed to below the judgment criterion, and by setting H / M to 0.5 (1 / 2), the zero point change rate can be further suppressed. Normally, when detecting torque using strain gauge 52, if the rate of change of the zero point of strain gauge 52 can be suppressed to a judgment criterion or less, the torque detection accuracy by strain gauge 52 can be maintained within a necessary range. Therefore, it has been suggested that by setting H / M to 0.25 (1 / 4) or more, preferably 0.5 (1 / 2), it is possible to suppress a decrease in the torque detection accuracy caused by screwing fasteners into screw holes 231, 232, 233, and 234.

[0029] In addition, as described above, in this embodiment, the screw holes 231, 232, 233, and 234 are disposed symmetrically with respect to the beam portion 4 in a plan view, so that it is possible to suppress uneven generation of distortion caused by screwing of the fasteners when the fasteners are screwed into the screw holes 231, 232, 233, and 234. Therefore, it is possible to suppress a decrease in torque detection accuracy due to the occurrence of uneven distortion.

[0030] The present embodiment as described above can provide the following effects. (1) In this embodiment, a screw hole 23 is formed in the second surface 22 of the first region 2, into which a fastener such as a bolt is screwed, without penetrating through to the first surface 21 on which the detection unit 5 is arranged. The thickness H between the bottom surface of the screw hole 23 and the first surface 21 is set to be equal to or greater than ¼ of the diameter M of the screw hole 23. This makes it possible to prevent distortion caused by the fastener being screwed into the screw hole 23 from being transmitted to the detection unit 5 when the fastener is screwed into the screw hole 23. Therefore, even if the screw hole 23 is provided in the first region 2, it is possible to prevent a decrease in the torque detection accuracy.

[0031] (2) In the present embodiment, the thickness H between the bottom surface of the screw hole portion 23 and the first surface 21 is preferably set to be equal to or greater than ½ of the diameter M of the screw hole portion 23. Therefore, even if the screw hole portion 23 is provided in the first region 2, a decrease in the torque detection accuracy can be more reliably prevented.

[0032] In this embodiment, the screw hole portions 231, 232, 233, and 234 are arranged symmetrically with respect to the beam portion 4 in a plan view. Therefore, when fasteners are screwed into the screw hole portions 231, 232, 233, and 234, it is possible to prevent distortion caused by the fasteners being screwed into the screw hole portions 231, 232, 233, and 234 from occurring unevenly.

[0033] [Second embodiment] Next, a second embodiment of the present invention will be described with reference to the drawings. In the second embodiment, the same or similar configurations as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted.

[0034] FIG. 5 is a plan view showing an outline of the torque sensor 1A of this embodiment, FIG. 6 is a plan view showing an outline of the torque sensor 1A seen from the opposite side to that of FIG. 5, and FIG. 7 is a cross-sectional view showing an outline of the torque sensor 1A taken along line VII-VII in FIG. 5. As shown in FIGS. 5 to 7, the torque sensor 1A includes a first region 2A, a second region 3, a beam portion 4, and a detection portion 5. The first region 2A is a first region 2A.

[0035] [First area 2A] The first region 2A is made of metal and formed in a circular ring shape, similar to the first region 2 of the first embodiment described above. The first region 2A has a first surface 21A and a second surface 22A opposite to the first surface 21A.

[0036] Further, screw holes 23A are formed in the second surface 22A of the first region 2A. In this embodiment, four screw holes 23A are formed: a first screw hole 231A, a second screw hole 232A, a third screw hole 233A, and a fourth screw hole 234A. A fastener such as a bolt can be screwed into each of the screw holes 231A, 232A, 233A, and 234A. In this embodiment, the screw holes 231A, 232A, 233A, and 234A are formed so as not to penetrate the first surface 21A. However, the screw holes 231A, 232A, 233A, and 234A are not limited to the above configuration, and may be formed so as to penetrate the first surface 21A.

[0037] In this embodiment, similarly to the first embodiment described above, the screw holes 231A, 232A, 233A, and 234A are disposed symmetrically with respect to the beam portion 4 in a plan view. Furthermore, the screw holes 231A, 232A, 233A, and 234A are arranged at equal intervals on an imaginary circle C having a center O.

[0038] [Method of forming the screw hole 23A and torque detection accuracy] Next, a method for forming the screw hole 23A and the torque detection accuracy will be described. As described above, the screw holes 231A, 232A, 233A, and 234A are formed in the second surface 22A of the first region 2A. In this case, the screw holes 231A, 232A, 233A, 234A are formed so that the distance L between the resistors R1, R2 of the strain gauge 52 and the outer periphery of the screw holes 231A, 232A, 233A, 234A in the direction in which the first surface 21A extends is at least half the diameter M of the screw holes 231A, 232A, 233A, 234A, preferably at least the diameter M (the same size).

[0039] Fig. 8 is a diagram showing the relationship between the ratio of the diameter M of the screw holes 231A, 232A, 233A, 234A to the distance L between the resistors R1, R2 of the strain gauge 52 and the outer periphery of the screw holes 231A, 232A, 233A, 234A, and the zero point change rate of the strain gauge 52. Note that Fig. 8 shows the zero point change rate when the judgment criterion is set to 1. FIG. 8 shows test results of the zero point change rate when screw holes 231A, 232A, 233A, and 234A having a diameter of about 3 to 5 mm are provided and bolts are screwed into the screw holes 231A, 232A, 233A, and 234A. 8, when L / M is smaller than 0.5 (1 / 2), it is suggested that when fasteners such as bolts are screwed into screw holes 231A, 232A, 233A, and 234A, the zero point change rate of strain gauge 52 exceeds the judgment criterion. On the other hand, it is suggested that by setting L / M to 0.5 (1 / 2) or more, the zero point change rate can be suppressed to below the judgment criterion, and by setting L / M to 1 (equal multiple), the zero point change rate can be further suppressed. This suggests that by setting L / M to 0.5 (1 / 2) or more, preferably 1 (equal size), it is possible to suppress the decrease in torque detection accuracy caused by screwing the fasteners into the screw holes 231A, 232A, 233A, and 234A.

[0040] The present embodiment as described above can provide the following effects. (4) In this embodiment, the second surface 22A of the first region 2A is formed with a screw hole 23A into which a fastener such as a bolt is screwed. The distance L between the resistors R1 and R2 of the strain gauge 52 and the outer periphery of the screw hole 23A in the extending direction of the first surface 21A is 1 / 2 mm. A The diameter M of the fastener is set to be equal to or larger than ½ of the diameter M of the fastener. This makes it possible to prevent distortion caused by the fastener being screwed into the screw hole portion 23A from being transmitted to the detection portion 5 when the fastener is screwed into the screw hole portion 23A. Therefore, even if the screw hole portion 23A is provided in the first region 2A, it is possible to prevent the torque detection accuracy from decreasing.

[0041] (5) In the present embodiment, it is preferable to set the distance L between the strain gauge 52 and the outer periphery of the screw hole portion 23A in the direction in which the first surface 21A extends to be equal to or smaller than the distance L between the strain gauge 52 and the outer periphery of the screw hole portion 23A. A Since the diameter is set to be equal to the diameter M of the screw hole 23A, even if the screw hole 23A is provided in the first region 2A, it is possible to more reliably prevent the torque detection accuracy from decreasing.

[0042] [Variations] The present invention is not limited to the above-described embodiments, and modifications and improvements within the scope of the present invention that can achieve the object of the present invention are included in the present invention.

[0043] In each of the above-described embodiments, the second region 3 is 2, 2A, but is not limited thereto. For example, the second region may be arranged inside the first region. That is, the detection unit and the screw hole portion may be provided in the first region arranged around the second region. In this case, the second region arranged inside the first region is fixed to the fixing member by a fastener such as a bolt.

[0044] In each of the above-described embodiments, the number of screw holes 23, 23A is four, but this is not limiting. For example, the number of screw holes may be eight, and may be an integer multiple of the number of beams. Furthermore, the present invention also includes cases where the number of screw holes is not an integer multiple of the number of beams.

[0045] In the above-described embodiments, the first region 2, 2A is formed in a circular ring shape, but is not limited thereto. For example, the first region may be formed in a rectangular shape in a plan view, or may be formed in a cross shape, etc.

[0046] In each of the above-described embodiments, the second region 3 is formed in a circular ring shape, but is not limited thereto. For example, the second region may be formed in a polygonal ring shape, and may be disposed so as to surround the first region. Furthermore, the second region may have recesses and protrusions in the thickness direction.

[0047] In each of the above-described embodiments, four beam portions 4 are provided, but this is not limiting. For example, five or more beam portions may be provided, or three or less beam portions may be provided, as long as a plurality of beam portions are provided. In addition, each beam portion does not have to be disposed in a position facing a pair of beam portions across the first region.

[0048] In the above-described embodiments, each of the beams 41, 42, 43, 44 is formed so that the end on the first region 2, 2A side and the end on the second region 3 side are wider than the center portion, but this is not limited thereto. For example, the beams may be formed so that the end and the center portion have the same width. In addition, the beams may have recesses or protrusions, as long as they are configured to connect the first region and the second region.

[0049] In the above-described embodiments, the insulating film 51 is made up of a plurality of layers, but the present invention is not limited to this. For example, the insulating film may be made up of a single insulating layer.

[0050] In each of the above-described embodiments, the detection unit 5 is configured to include the insulating film 51 and the strain gauge 52, but is not limited thereto. For example, the detection unit may be configured to include a protective film that covers the strain gauge.

[0051] In the above-described embodiments, the resistors R1 and R2 are formed by printing, but this is not limiting. For example, the resistors may be formed by deposition or sputtering, or may be attached to an insulating film.

[0052] In the above-described embodiments, the insulating film 51 is laminated so as to cover substantially the entire surface of the first region 2, 2A, but is not limited thereto. For example, the insulating film may be laminated so as to cover a part of the first region, and it is sufficient that the insulating film is laminated at least at the position where the strain gauge, the conductor, and the electrode are arranged. In other words, it is sufficient that the insulating film is arranged so as to insulate the strain gauge, the conductor, and the electrode from the first region.

[0053] In each of the above embodiments, the device may be configured to include a plurality of bridge circuits each having a strain gauge, for example, a first bridge circuit and a second bridge circuit, and may be configured to include a determination unit that determines whether or not a difference in output between the first bridge circuit and the second bridge circuit exceeds a predetermined range. With this configuration, when an abnormality occurs in either the first bridge circuit or the second bridge circuit configured with the strain gauge, the abnormality can be detected.

[0054] In the above-described embodiments, the strain gauge 52 is provided in the first region 2, 2A, but the present invention is not limited to this. For example, the strain gauge may be provided in the beam portion.

[0055] In each of the above-described embodiments, the torque sensor 1 is mounted on a joint of a robot or the like, but is not limited thereto. For example, the torque sensor may be mounted on a transport machine such as a car, or an industrial machine such as a processing device, and can be applied to locations where torque acts in various fields. [Explanation of symbols]

[0056] 1,1A...torque sensor, 2,2A...first region, 3...second region, 4...beam portion, 21,21A...first surface, 22,22A...second surface, 23,23A...screw hole portion, 5...detection portion, 51...insulating film, 52...strain gauge, 41...first beam portion, 42...second beam portion, 43...third beam portion, 44...fourth beam portion, 231,231A...first screw hole portion, 232,232A...second screw hole portion, 233,233A...third screw hole portion, 234,234A...fourth screw hole portion, R1...resistor, R2...resistor.

Claims

1. a first region having a first surface and a second surface opposite the first surface; a second region disposed around the first region or inside the first region; A plurality of beam portions connecting the first region and the second region; a detection unit configured to detect a torque acting between the first region and the second region and disposed on the first surface of the first region; the detection unit includes an insulating film laminated on the first region, and a strain gauge laminated on the insulating film and configured to be deformable in response to the torque, A screw hole portion is formed in the second surface of the first region, the screw hole portion not penetrating the first surface and into which a fastener is screwed, The thickness between the bottom surface of the screw hole and the first surface is set to be equal to or greater than ¼ of the diameter of the screw hole. A torque sensor characterized by:

2. 2. The torque sensor according to claim 1, The thickness between the bottom surface of the screw hole and the first surface is set to be equal to or greater than ½ of the diameter of the screw hole. A torque sensor characterized by:

3. a first region having a first surface and a second surface opposite the first surface; a second region disposed around the first region or inside the first region; A plurality of beam portions connecting the first region and the second region; a detection unit configured to detect a torque acting between the first region and the second region and disposed on the first surface of the first region; the detection unit includes an insulating film laminated on the first region, and a strain gauge laminated on the insulating film and configured to be deformable in response to the torque, A screw hole portion into which a fastener is screwed is formed on the second surface of the first region, The distance between the strain gauge and the outer periphery of the screw hole portion in the extending direction of the first surface is set to be equal to or greater than ½ of the diameter of the screw hole portion. A torque sensor characterized by:

4. 4. The torque sensor according to claim 3, A distance between the strain gauge and an outer periphery of the screw hole portion in a direction in which the first surface extends is set to be equal to or greater than a diameter of the screw hole portion. A torque sensor characterized by:

5. The torque sensor according to claim 1 or 2, The number of the screw holes is an integer multiple of the number of the beam portions, The plurality of screw holes are disposed at positions corresponding to the beam portion when viewed from a center point of the first region, and are equally spaced on a virtual circle having the center point as a center. A torque sensor characterized by:

Images