Detection body and detection system

Abstract

A detection body that detects a tightening axial force applied in an axial direction by a tightening mechanism, the detection body including: a strain generator having a through-hole through which a bolt portion of the tightening mechanism is inserted; and a strain detection sensor that detects a strain of the strain generator, the strain generator being formed in a block shape and having a flat surface portion on a side in the axial direction, and the strain detection sensor being disposed on the flat surface portion.

Description

TECHNICAL FIELD

[0001] The present application relates to a detection body and a detection system. BACKGROUND

[0002] In the past, there has been a technique in which, for a strain of a member (a strain generator) fixed to a setting surface by a fastening member (for example, a bolt, a nut, or the like), a strain sensor provided to the member is used to detect the strain, and thus it is possible to detect loosening of the fastening member.

[0003] For example, Patent Literature 1 discloses a technique in which a strain gauge is attached to an outer peripheral surface of a cylindrical body having a flange shape. Further, for example, Patent Literature 2 discloses a technique in which a strain gauge is provided in the vicinity of a bolt in a fixing portion of a motor, and thus it is possible to detect generation of loosening of the bolt.

[0004] PRIOR ART DOCUMENTS

[0005] PATENT LITERATURE

[0006] Patent Literature 1: Japanese Patent Application Publication No. 2005-013383

[0007] Patent Literature 2: Japanese Patent Application Publication No. 2019-080389 SUMMARY

[0008] PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] However, in the technique of Patent Literature 1, since the outer peripheral surface of the cylindrical body to which the strain gauge is attached is curved, it is difficult to attach the strain gauge, and there is a risk that the strain gauge is not properly set. Thus, in the technique of Patent Literature 1, there is a risk that the detection accuracy of the strain of the cylindrical body by the strain gauge is reduced due to improper setting of the strain gauge.

[0010] Further, in the technique of Patent Literature 2, since the strain gauge and the head of the bolt are horizontally provided on the same surface on the upper surface of the fixing portion, it is not possible to accurately detect a slight strain of the fixing portion (i.e., slight loosening of the bolt) by the strain gauge.

[0011] To solve the above-described problems, an object of one embodiment is to improve the detection accuracy of a strain of a strain generator by a strain gauge provided to the strain generator.

[0012] MEANS FOR SOLVING THE PROBLEMS

[0013] A detection body of one embodiment detects a tightening axial force applied in the axial direction by a tightening mechanism, and includes a strain generating body having a through-hole through which a bolt portion of the tightening mechanism is inserted, and a strain sensing sensor that senses a strain of the strain generating body. The strain generating body is formed in a block shape and has a flat surface on a side in the axial direction. The strain sensing sensor is provided to the flat surface.

[0014] In addition, another detection body of one embodiment detects a tightening axial force applied in the axial direction by a tightening mechanism, and includes a strain generating body having a through-hole through which a bolt portion of the tightening mechanism is inserted, and a strain sensing sensor that senses a strain of the strain generating body. The strain generating body includes a block-shaped base portion having the through-hole, and a thin plate-shaped protruding portion that is provided to protrude from an outer side of the base portion in a direction intersecting the axial direction. The strain sensing sensor is provided to the protruding portion.

[0015] Effects of Invention

[0016] According to one embodiment, the strain sensing accuracy of a strain gauge provided to a strain generating body can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 FIG. 1 is a perspective view illustrating an appearance of an upper surface side of a detection body of a first embodiment.

[0018] Figure 2 FIG. 1 is a perspective view illustrating an appearance of an upper surface side of a detection body of a first embodiment.

[0019] Figure 3 FIG. 2 is an exploded perspective view of the detection body of the first embodiment.

[0020] Figure 4 FIG. 3 is a view illustrating a configuration position of a strain detection element in the detection body of the first embodiment.

[0021] Figure 5 FIG. 4 is a circuit diagram of a bridge circuit included in the detection body of the first embodiment.

[0022] Figure 6 FIG. 5 is a view illustrating an example of dimensions of each portion of the detection body of the first embodiment.

[0023] Figure 7 FIG. 6 is a view illustrating a use example of the detection body of the first embodiment.

[0024] Figure 8 FIG. 7 is a perspective view illustrating an appearance of an upper surface side of a detection body of a second embodiment.

[0025] Figure 9is a perspective view showing the appearance of the upper surface side of the detection body of the second embodiment.

[0026] Figure 10 is an exploded perspective view of the detection body of the second embodiment.

[0027] Figure 11A is a view showing the arrangement positions of the strain detection elements in the detection body of the second embodiment.

[0028] Figure 11B is a view showing the arrangement positions of the strain detection elements in the detection body of the second embodiment.

[0029] Figure 12 is a circuit diagram of the bridge circuit provided in the detection body of the second embodiment.

[0030] Figure 13 is a view showing an example of the dimensions of each part of the detection body of the second embodiment.

[0031] Figure 14 is a view showing an example of the dimensions of each part of the detection body of the second embodiment.

[0032] Figure 15 is a view showing the system structure of the detection system of the third embodiment.

[0033] Figure 16 is a perspective view showing the appearance of the upper surface side of the detection body of the third embodiment.

[0034] Figure 17 is a view showing the structure of the cover provided in the reading device of the third embodiment.

[0035] Figure 18 is a view showing the structure of the control circuit provided in the detection body of the third embodiment.

[0036] Figure 19 is a flowchart showing the operation sequence of the detection body of the third embodiment.

[0037] Figure 20 is a chart showing an example of the correction data for offset correction and slope correction of sensor values used by the reading device of the third embodiment.

[0038] Figure 21 is a chart showing an example of the correction data for temperature correction of sensor values used by the reading device 0 of the third embodiment.

[0039] Figure 22 is a view showing an example of the input / output characteristics of the detection body of the third embodiment.

[0040] Figure 23is a graph showing changes in the resistance value of the sensor provided in the detection body of the third embodiment with respect to strain.

[0041] Figure 24 is a graph showing a first modification example of the arrangement position of the sensor in the strain generator of the third embodiment.

[0042] Figure 25 is a graph showing a second modification example of the arrangement position of the sensor in the strain generator of the third embodiment.

[0043] Figure 26 is a graph showing evaluation results of the detection body of the third embodiment.

[0044] Figure 27 is an exploded view of the fastening structure of the fourth embodiment.

[0045] Figure 28 is a graph showing a fastened state of the fastening structure of the fourth embodiment.

[0046] Figure 29 is a graph showing measurement results of the strain amount of the strain generator in the fastening structure of the fourth embodiment (in a case where the gasket is not provided).

[0047] Figure 30 is a graph showing measurement results of the strain amount of the strain generator in the fastening structure of the fourth embodiment (in a case where the gasket is not provided).

[0048] Figure 31 is a graph showing measurement results of the strain amount of the strain generator in the fastening structure of the fourth embodiment (in a case where the gasket is provided).

[0049] Figure 32 is a graph showing measurement results of the strain amount of the strain generator in the fastening structure of the fourth embodiment (in a case where the gasket is provided). DETAILED DESCRIPTION

[0050] Hereinafter, an embodiment will be described. Note that, in the following description, for convenience, the Z-axis direction (the axial direction of the central axis X described later) in the drawing is set as the up-down direction, the X-axis direction (the lateral direction of the planar portion 16A described later) in the drawing is set as the left-right direction, and the Y-axis direction (the perpendicular direction of the planar portion 16A described later) in the drawing is set as the front-rear direction. In addition, the X-axis direction in the drawing and the Y-axis direction in the drawing are set as the horizontal direction.

[0051] [First Embodiment]

[0052] (Summary of Detection Body 10)

[0053] Figure 1is a perspective view showing the appearance of the upper surface side of the detection body 10 of the first embodiment. Figure 1 The detection body 10 shown is a device having a substantially cylindrical shape. The detection body 10 is disposed between a fastening member (a bolt or a nut) and a fastened member when the fastening member is threadedly fastened and fixed with respect to a prescribed mounting surface (for example, a wall surface), so that a fastening axial force applied in the axial direction of the center axis XI by the fastening of the fastening member can be detected.

[0054] As shown in Figure 1 , the detection body 10 is provided with a strain generator 12 and a strain detection module 20. The strain generator 12 is a block-shaped member having a substantially cylindrical shape. The strain generator 12 is formed, for example, using a metal raw material such as stainless steel. A through-hole 14 that penetrates the strain generator 12 in the up-down direction (Z-axis direction) along the center axis XI is formed in the center of the strain generator 12. The through-hole 14 is a portion through which a bolt portion possessed by a fastening mechanism 42 (refer to Figure 7 ) is inserted.

[0055] Note that, in the case where the fastening member is a nut, the "bolt portion" is a bolt shaft that is fixed to the mounting surface. That is, in the case where the fastening member is a nut, the fastening mechanism 42 is constituted by the nut and the bolt shaft that is fixed to the mounting surface.

[0056] On the other hand, in the case where the fastening member is a bolt, the "bolt portion" is the bolt shaft of the bolt. That is, in the case where the fastening member is a bolt, the fastening mechanism 42 is constituted by the bolt and the nut that is fixed to the mounting surface.

[0057] In addition, as shown in Figure 1 , a circular ring-shaped seating portion 18 that is centered on the center axis XI and surrounds the through-hole 14 is formed on the upper surface of the strain generator 12. The seating portion 18 is a portion that is slightly higher in height position than the peripheral portion of the seating portion 18 in the upper surface of the strain generator 12. The upper surface 18A of the seating portion 18 functions as a planar receiving portion that receives the fastening member (the bolt or the nut).

[0058] In addition, as shown in Figure 1 , a pair of planar portions 16A, 16B are formed on the side surface of the strain generator 12 so as to sandwich the through-hole 14 therebetween in the front-rear direction (Y-axis direction). The pair of planar portions 16A, 16B are parallel to each other and both are parallel with respect to the XZ plane. The planar portion 16A is formed at a position closer to the center axis XI than the planar portion 16B. Due to this, the planar portion 16A has a wider area than the planar portion 16B. The pair of planar portions 16A, 16B are formed, for example, by parallelly cutting a portion of the outer peripheral surface of the strain generator 12 before processing having a cylindrical shape with respect to the XZ plane.

[0059] The strain detection module 20 is provided to the flat portion 16A in the side surface of the strain generating body 12. The strain detection module 20 is capable of detecting the strain of the strain generating body 12, and outputting a strain detection signal, which indicates the magnitude of the detected strain with a voltage value, to the outside through wireless communication. As shown in Figure 1 , the strain detection module 20 is provided with a sealing resin 25 that covers the entire strain detection module 20. The sealing resin 25 protects the other constituent components and the flat portion 16A of the strain generating body 12 from rain, dirt, and the like by covering the entire strain detection module 20 and the flat portion 16A of the strain generating body 12. In addition, the sealing resin 25 is formed in a shape that follows the outer shape of the strain generating body 12 so as not to cause a discordance in the appearance. However, the outer shape of the sealing resin 25 is not limited to this, and can be any shape. For example, the outer shape of the sealing resin 25 can also be a shape that is naturally formed by potting.

[0060] (Structure of Strain Detection Module 20)

[0061] Figure 2 is a perspective view showing the appearance of the upper surface side of the detection body 10 of the first embodiment. Figure 3 is an exploded perspective view of the detection body 10 of the first embodiment. In Figure 2 , the sealing resin 25 of the strain detection module 20 is shown in a transparent state.

[0062] As shown in Figure 2 and Figure 3 , the strain detection module 20 is provided with a strain detection sensor 21, a wiring pattern 22, an IC (Integrated Circuit) 23, a communication antenna 24, and a sealing resin 25.

[0063] The strain detection sensor 21 has a first strain detection element 21A, a second strain detection element 21B, a third strain detection element 21C, and a fourth strain detection element 21D. The strain detection elements 21A to 21D are each disposed to the flat portion 16A. The strain detection elements 21A to 21D each detect the strain of the strain generating body 12. For example, the strain detection elements 21A to 21D each use a strain resistance element whose resistance value changes according to the amount of strain. The strain detection elements 21A to 21D constitute a bridge circuit 30 (refer to Figure 5 ). Note that the disposition positions of the strain detection elements 21A to 21D will be described later. Figure 4

[0064] ​The wiring pattern 22 is a member having conductivity formed in the planar portion 16A and connecting each of the strain detection elements 21A to 21D and the IC 23 and connecting the communication antenna 24 and the IC 23. The wiring pattern 22 is used for transmission of the strain detection signal between each of the strain detection elements 21A to 21D and the IC 23 and between the communication antenna 24 and the IC 23. The wiring pattern 22 is formed using, for example, a thin film conductor such as a copper foil.

[0065] The IC 23 is an example of a "control circuit". The IC 23 is provided in the planar portion 16A and controls the operation of the strain detection module 20. For example, the IC 23 acquires the strain detection signal indicating the magnitude of the strain of the strain generation body 12 from the bridge circuit 30 composed of the strain detection elements 21A to 21D via the wiring pattern 22. Also, the IC 23 wirelessly transmits the strain detection signal acquired from the bridge circuit 30 to an external device using the communication antenna 24.

[0066] The communication antenna 24 is used for transmission of the strain detection signal. The communication antenna 24 has a radiating surface 24A formed by bending a thin plate-like and band-like conductor multiple times in the same planar shape. The radiating surface 24A is arranged in parallel with the planar portion 16A and separately from the planar portion 16A. The communication antenna 24 is connected to the wiring pattern 22 formed in the planar portion 16A by two leg portions 24B provided in both end portions of the radiating surface 24A and perpendicular to the radiating surface 24A.

[0067] (Position of the strain detection elements 21A to 21D)

[0068] Figure 4 is a view showing the position of the strain detection elements 21A to 21D in the detection body 10 of the first embodiment. Figure 4 represents a side surface of the detection body 10 when the planar portion 16A is viewed from the negative side of the Y axis.

[0069] As shown in Figure 4 , the first strain detection element 21A and the second strain detection element 21B are arranged in the left-right direction (X axis direction) with the center axis X1 interposed therebetween in the vicinity of the lower end portion (end portion on the negative side of the Z axis) of the planar portion 16A. The first strain detection element 21A is provided at a position on the left side of the center axis X1, and the second strain detection element 21B is provided at a position on the right side of the center axis X1. The first strain detection element 21A and the second strain detection element 21B are provided at positions equally spaced from the center axis X1. In particular, the first strain detection element 21A is provided at a position overlapping with the left end position of the inner peripheral surface of the through-hole 14, and the second strain detection element 21B is provided at a position overlapping with the right end position of the inner peripheral surface of the through-hole 14.

[0070] These setting positions are positions at which the present inventors found, through simulation, that greater positive strain (strain in the compression direction) is generated in each of the first and second strain detection elements 21A and 21B when the fastening axial force is applied to the strain generator 12 in the axial direction of the central axis Xl.

[0071] In addition, as shown in FIG. 2, the third and fourth strain detection elements 21C and 21D are arranged in the up-and-down direction (Z-axis direction) at positions overlapping the central axis Xl in the central portion of the up-and-down direction (Z-axis direction) in the planar portion 16A. The third strain detection element 21C is disposed on the upper side, and the fourth strain detection element 21D is disposed on the lower side. Figure 4

[0072] These setting positions are positions at which the present inventors found, through simulation, that greater negative strain (strain in the tensile direction) is generated in each of the third and fourth strain detection elements 21C and 21D when the fastening axial force is applied to the strain generator 12 in the axial direction of the central axis Xl.

[0073] Note that the strain detection elements 21A to 21D can be arranged in the planar portion 16A by various arrangement methods.

[0074] For example, the strain detection elements 21A to 21D can be directly attached to the planar portion 16A by an adhesive or the like.

[0075] In addition, for example, the strain detection elements 21A to 21D can be formed in the planar portion 16A by printing a metal ceramic or a synthetic resistor body of a synthetic resin adhesive in the planar portion 16A. In this case, the strain detection elements 21A to 21D can be easily and reliably arranged at the prescribed setting positions in the planar portion 16A. In particular, in this case, the printing, drying, and curing of the strain detection elements 21A to 21D can be performed collectively for the plurality of strain generators 12 in a state in which the plurality of strain generators 12 are arranged side by side, and thus the strain detection elements 21A to 21D can be easily and reliably arranged in the plurality of strain generators 12.

[0076] In addition, for example, the strain detection elements 21A to 21D can be attached to the planar portion 16A together with a rigid substrate or a flexible substrate in a state in which the strain detection elements 21A to 21D are mounted to the rigid substrate or the flexible substrate. In this case, since the arrangement surface is a planar surface, the strain detection elements 21A to 21D can be easily and reliably arranged at the prescribed setting positions in the planar portion 16A.

[0077] (Structure of the bridge circuit 30)

[0078] Figure 5 ​is a circuit diagram of the bridge circuit 30 provided in the detection body 10 of the first embodiment. As shown in Figure 5 The bridge circuit 30 is configured to include the strain detection elements 21A to 21D.

[0079] In the bridge circuit 30 shown in Figure 5 The strain detection elements 21C and 21D have larger resistance values as the fastening axial force in the axial direction of the center axis XI of the strain generation body 12 increases. On the other hand, the strain detection elements 21A and 21B have smaller resistance values as the fastening axial force in the axial direction of the center axis XI of the strain generation body 12 increases.

[0080] Therefore, in the bridge circuit 30, the voltage value Vp at the connection point of the strain detection element 21B and the strain detection element 21D increases as the fastening axial force in the axial direction of the center axis XI of the strain generation body 12 increases. In addition, the voltage value Vn at the connection point of the strain detection element 21A and the strain detection element 21C decreases as the fastening axial force in the axial direction of the center axis XI of the strain generation body 12 increases.

[0081] The bridge circuit 30 outputs the voltage difference between the voltage value Vp and the voltage value Vn by differential amplification (omitted from illustration). Thus, the bridge circuit 30 can output a strain detection signal whose voltage value increases as the fastening axial force in the axial direction of the center axis XI of the strain generation body 12 increases.

[0082] Note that the fastening torque of the fastening member and the fastening axial force in the axial direction of the center axis XI of the strain generation body 12 are in a proportional relationship with each other. That is, as the fastening torque of the fastening member increases, the fastening axial force in the axial direction of the center axis XI of the strain generation body 12 increases. Thus, the bridge circuit 30 can output a strain detection signal whose voltage value increases as the fastening torque of the fastening member increases.

[0083] (Example of dimensions of each part of the detection body 10)

[0084] Figure 6 is a diagram showing an example of dimensions of each part of the detection body 10 of the first embodiment. Figure 6 An example of dimensions of each part of the detection body 10 when the detection body 10 is used for installation to a bolt shaft having a diameter of 8 mm is shown. In Figure 6 In the example shown in

[0085] (Example of use of detection body 10)

[0086] Figure 7 is a view showing an example of use of the detection body 10 of the first embodiment. Figure 7 indicates an example in which the flat fastened member 43 is threadedly fastened and fixed to the mounting surface 41 by the nut 42B.

[0087] In Figure 7 the example shown, the detection body 10 is disposed between the nut 42B and the fastened member 43. The bolt shaft 42A extending upward from the mounting surface 41 is threaded through the strain generator 12 of the fastened member 43 and the detection body 10. The tip end portion (end portion on the negative side of the Z-axis) of the bolt shaft 42A is fixed to the mounting surface 41. The nut 42B is threadedly tightened with respect to the bolt shaft 42A from the front end portion (end portion on the positive side of the Z-axis) of the bolt shaft 42A. The nut 42B constitutes the fastening mechanism 42 together with the bolt shaft 42A.

[0088] In Figure 7 the example shown, when the nut 42B is threadedly tightened, the fastened member 43 and the detection body 10 are fixed with respect to the mounting surface 41. At this time, the strain generator 12 of the detection body 10 receives the nut 42B on the upper surface 18A of the seating portion 18 formed on the upper surface thereof. Thus, the strain generator 12 is subjected to the fastening axial force of the bolt shaft 42A in the axial direction (Z-axis direction). Here, the diameter of the seating portion 18 is larger than the maximum size (length of the diagonal line) of the nut. Thus, the strain generator 12 can more reliably receive the fastening axial force applied from the nut 42B by the upper surface 18A of the seating portion 18.

[0089] As a result, the strain corresponding to the fastening torque of the nut 42B is generated in the strain generator 12. The strain generated in the strain generator 12 is detected by the strain detection elements 21A to 21D (refer to Figures 3-5 ) provided in the strain sensing module 20 of the detection body 10, respectively. Also, the bridge circuit 30 (refer to Figure 5 ) provided in the strain sensing module 20 outputs the strain detection signal corresponding to the fastening torque of the nut 42B to the IC 23 provided in the strain sensing module 20, based on the strain detected by each of the strain detection elements 21A to 21D (i.e., the change in the resistance value of each of the strain detection elements 21A to 21D). The IC 23 outputs the strain detection signal acquired from the bridge circuit 30 to the external device via wireless communication. For example, the external device can determine the fastening state of the nut 42B based on the voltage value indicated by the strain detection signal acquired from the detection body 10.

[0090] Note that, as the output method of the strain detection signal output by the strain detection module 20, various output methods can be employed. For example, the strain detection module 20 can generate electric power using the power generation coil when the tag reader covers the strain detection module 20, and wirelessly transmit the strain detection signal to the tag reader using the electric power. In this case, the strain detection module 20 can be configured without a battery and a memory. However, the strain detection module 20 can also be configured with at least either of a battery and a memory.

[0091] As described above, the detection body 10 of the first embodiment detects the fastening axial force applied by the fastening mechanism 42 in the central axis X1 direction, and the detection body 10 includes the strain generator 12 having the through-hole 14 through which the bolt portion of the fastening mechanism 42 is inserted, and the strain detection sensor 21 that detects the strain of the strain generator 12, the strain generator 12 is formed in a block shape and has the flat portion 16A on the side surface in the central axis X1 direction, and the strain detection sensor 21 is provided to the flat portion 16A.

[0092] Thus, the detection body 10 of the first embodiment can provide the strain detection sensor 21 to the flat portion 16A of the side surface of the strain generator 12, and thus can easily and reliably provide the strain detection sensor 21 to a predetermined arrangement position in the flat portion 16A. Thus, according to the detection body 10 of the first embodiment, it is possible to improve the detection accuracy of the strain of the strain generator 12 detected by the strain detection sensor 21 provided to the strain generator 12.

[0093] In addition, in the detection body 10 of the first embodiment, the strain detection sensor 21 has the first strain detection element 21A and the second strain detection element 21B arranged in the horizontal direction (first direction) orthogonal to the central axis X1 direction on the flat portion 16A.

[0094] Thus, the detection body 10 of the first embodiment can detect the strain of two portions in the horizontal direction (first direction) of the flat portion 16A of the strain generator 12, and thus can detect the strain of the strain generator 12 in the horizontal direction with high accuracy. Thus, according to the detection body 10 of the first embodiment, it is possible to further improve the detection accuracy of the strain of the strain generator 12 detected by the strain detection sensor 21 provided to the strain generator 12.

[0095] In addition, in the detection body 10 of the first embodiment, the first strain detection element 21A and the second strain detection element 21B are arranged on the bottom surface side of the strain generator 12, and are arranged in the central axis X1 direction while sandwiching the central axis X1 of the through-hole 14.

[0096] Thus, the detection body 10 of the first embodiment can detect the strain of two portions in which the amount of strain in the horizontal direction in the planar portion 16A of the strain generating body 12 is large, and thus can detect the strain in the horizontal direction of the strain generating body 12 with higher accuracy. Thus, according to the detection body 10 of the first embodiment, it is possible to further improve the detection accuracy of the strain of the strain generating body 12 detected by the strain detection sensor 21 provided to the strain generating body 12.

[0097] In addition, in the detection body 10 of the first embodiment, the strain detection sensor 21 further has a third strain detection element 21C and a fourth strain detection element 21D arranged in the second direction (the vertical direction) along the central axis X1 direction of the planar portion 16A.

[0098] Thus, the detection body 10 of the first embodiment can detect the strain of two portions in which the amount of strain in the central axis X1 direction in the planar portion 16A of the strain generating body 12 is large, and thus can detect the strain in the central axis X1 direction of the strain generating body 12 with high accuracy. Thus, according to the detection body 10 of the first embodiment, it is possible to further improve the detection accuracy of the strain of the strain generating body 12 detected by the strain detection sensor 21 provided to the strain generating body 12.

[0099] In addition, in the detection body 10 of the first embodiment, in a case where the planar portion 16A is viewed from above, the third strain detection element 21C and the fourth strain detection element 21D are arranged at positions overlapping with the central axis X1 of the through-hole 14.

[0100] Thus, the detection body 10 of the first embodiment can detect the strain of two portions in which the amount of strain in the central axis X1 direction in the planar portion 16A of the strain generating body 12 is large, and thus can detect the strain in the central axis X1 direction of the strain generating body 12 with high accuracy. Thus, according to the detection body 10 of the first embodiment, it is possible to further improve the detection accuracy of the strain of the strain generating body 12 detected by the strain detection sensor 21 provided to the strain generating body 12.

[0101] In addition, in the detection body 10 of the first embodiment, the strain detection sensor 21 has the bridge circuit 30 configured to have the first strain detection element 21A, the second strain detection element 21B, the third strain detection element 21C, and the fourth strain detection element 21D.

[0102] Thus, the detection body 10 of the first embodiment can output, as a voltage value representing the strain of the strain generation body 12, a voltage value based on the resistance value of each of the four strain detection elements 21A to 21D using the bridge circuit 30. In particular, the detection body 10 of the first embodiment has two strain detection elements each arranged in two directions (the first direction and the second direction) orthogonal to each other in the strain generation body 12, and thus can further detect the difference between them. Thus, according to the detection body 10 of the first embodiment, the detection accuracy of the strain of the strain generation body 12 detected by the strain detection sensor 21 provided to the strain generation body 12 can be further improved.

[0103] In addition, in the detection body 10 of the first embodiment, the strain generation body 12 has a flat receiving portion that receives the fastening member of the fastening mechanism 42 around the through-hole 14 on the upper surface.

[0104] Thus, the detection body 10 of the first embodiment can more reliably receive the fastening axial force applied from the fastening member using the receiving portion. That is, the fastening state of the fastening member can be more reliably converted into the strain of the strain generation body 12. Thus, according to the detection body 10 of the first embodiment, the detection accuracy of the strain of the strain generation body 12 detected by the strain detection sensor 21 provided to the strain generation body 12 can be further improved.

[0105] In addition, the detection body 10 of the first embodiment further includes the IC 23 and the communication antenna 24.

[0106] Thus, the detection body 10 of the first embodiment can output high-precision detection data representing the strain of the strain generation body 12 detected by the strain detection sensor 21 to the outside through wireless communication. Thus, according to the detection body 10 of the first embodiment, the detection accuracy of the strain of the strain generation body 12 detected by the strain detection sensor 21 provided to the strain generation body 12 can be improved outside.

[0107] In addition, in the detection body 10 of the first embodiment, the IC 23 and the communication antenna 24 are provided to the flat portion 16A.

[0108] Thus, the detection body 10 of the first embodiment can arrange the strain detection sensor 21, the IC 23, and the communication antenna 24 in the flat portion 16A of the strain generation body 12 in one portion. Thus, according to the detection body 10 of the first embodiment, the detection body 10 can be miniaturized.

[0109] In addition, the detection body 10 of the first embodiment further includes the sealing resin 25 that seals the flat portion 16A.

[0110] Thus, the detection body 10 of the first embodiment can protect the strain detection sensor 21, the IC 23, and the communication antenna 24 together with the sealing resin 25. Therefore, according to the detection body 10 of the first embodiment, the long life of the above-described plurality of constituent members can be achieved.

[0111] [Second Embodiment]

[0112] (Summary of Detection Body 50)

[0113] Figure 8 is a perspective view showing the appearance of the upper surface side of the detection body 50 of the second embodiment. Figure 8 The detection body 50 shown is a device having a substantially cylindrical shape. When the detection body 50 is threadedly fastened and fixed to a prescribed mounting surface (for example, a wall surface) by a fastening member (a bolt or a nut), the detection body 50 is disposed between the fastening member and the fastened member, so that the fastening axial force applied in the axial direction of the center axis X2 by the fastening of the fastening member can be detected.

[0114] As shown in Figure 8 , the detection body 50 is provided with a strain generator 52 and a strain detection module 60. The strain generator 52 has a cylindrical base portion 52A and a thin plate-shaped protruding portion 52B (see Figure 10 ) that is provided so as to protrude in the horizontal direction (a direction intersecting the axial direction of the center axis X2) from the outside (the outer peripheral surface) of the lower end portion of the base portion 52A. That is, the protruding portion 52B has a circular ring shape that surrounds the base portion 52A when viewed from above (the Z-axis positive direction) (see FIG. 11). The strain generator 52 is preferably formed, for example, using a metal raw material such as stainless steel. Note that the base portion 52A and the protruding portion 52B are formed integrally. In addition, a through-hole 54 that penetrates the strain generator 52 in the vertical direction (the Z-axis direction) along the center axis X2 is formed in the center of the strain generator 52. The through-hole 54 is a portion through which a bolt portion of the fastening mechanism 42 (see Figure 14 ) is inserted. The upper surface 52A1 of the base portion 52A is circular ring-shaped and planar, and functions as a planar receiving portion that receives a fastening member (a bolt or a nut).

[0115] The strain detection module 60 is disposed on the upper surface 52B1 (see Figure 9 ) of the protruding portion 52B of the strain generator 52. The strain detection module 60 can detect the strain of the strain generator 52 and output a strain detection signal indicating the magnitude of the detected strain using a voltage value to the outside through wireless communication. As Figure 8As shown, the strain detection module 60 includes a sealing resin 65. The sealing resin 65 protects the other components of the strain detection module 60 and the entire upper surface of the protrusion 52B of the strain generator 52 from rainwater, dirt, and other contaminants by covering the entire surface of the protrusion 52B. Furthermore, the sealing resin 65 is formed in a shape that follows the external shape of the strain generator 52 to avoid visual disharmony. Specifically, the sealing resin 65 is formed into a cylindrical shape having an outer diameter approximately the same size as the diameter of the protrusion 52B and an inner diameter approximately the same size as the diameter of the base 52A. However, this is not a limitation; the external shape of the sealing resin 65 can be any shape. For example, the external shape of the sealing resin 65 can also be a shape naturally formed through potting.

[0116] (Structure of strain detection module 60)

[0117] Figure 9 This is a perspective view showing the appearance of the upper surface side of the detector 50 according to the second embodiment. Figure 10 This is an exploded perspective view of the detection body 50 according to the second embodiment. Among them, in Figure 9 In the middle, the sealing resin 65 of the strain detection module 60 is shown to be transparent.

[0118] like Figure 9 as well as Figure 10 As shown, the strain detection module 60 includes a strain detection sensor 61, a second strain detection element 61B, a wiring pattern 62, an IC 63, a communication antenna 64, and a sealing resin 65.

[0119] The strain detection sensor 61 has a first strain detection element 61A and a second strain detection element 61B. Strain detection elements 61A and 61B are each disposed on the upper surface 52B1 of the protrusion 52B of the strain generator 52. Specifically, strain detection elements 61A and 61B are disposed on the upper surface 52B1 at positions opposite to each other across the central axis X2. Strain detection elements 61A and 61B each detect the strain of the strain generator 52. For example, strain detection elements 61A and 61B each use a strain resistor element whose resistance value varies according to the strain. Strain detection elements 61A and 61B constitute a bridge circuit 70 (see reference). Figure 12 It should be noted that the respective configuration positions of strain detection elements 61A and 61B will be described later with reference to Figure 11.

[0120] The wiring pattern 62 is a band-shaped member having conductivity formed on the upper surface 52B1 of the protruding portion 52B, and connects each of the strain detection elements 61A and 61B and the IC 63 and connects the communication antenna 64 and the IC 63. The wiring pattern 62 is used for transmission of the strain detection signal between each of the strain detection elements 61A and 61B and the IC 63 and between the communication antenna 64 and the IC 63. The wiring pattern 62 is formed using, for example, a thin film conductor such as a copper foil.

[0121] The IC 63 is an example of a "control circuit". The IC 63 is provided on the upper surface 52B1 of the protruding portion 52B, and controls the operation of the strain detection module 60. For example, the IC 63 acquires a strain detection signal indicating the magnitude of the strain of the strain generation body 52 from the bridge circuit 70 composed of the strain detection elements 61A and 61B via the wiring pattern 62. Also, the IC 63 wirelessly transmits the strain detection signal acquired from the bridge circuit 70 to an external device using the communication antenna 64.

[0122] The communication antenna 64 is used for transmission of the strain detection signal. The communication antenna 64 has a loop-shaped radiation surface 64A composed of a thin plate-shaped and band-shaped conductor. The radiation surface 64A is arranged in parallel to and apart from the upper surface 52B1 of the protruding portion 52B. The communication antenna 64 is connected to the wiring pattern 62 formed on the upper surface 52B1 of the protruding portion 52B by a plurality of leg portions 64B provided at the outer and inner peripheral edge portions of the radiation surface 64A, respectively, and perpendicular to the radiation surface 64A.

[0123] (Position of the strain detection elements 61A and 61B)

[0124] Fig. 11 is a view showing the position of the strain detection elements 61A and 61B in the detection body 50 of the second embodiment. Figure 11A The state of the upper surface 52B1 of the strain generation body 52 is shown in plan view. Figure 11B The state of the bottom surface 52B2 of the strain generation body 52 is shown in plan view.

[0125] As shown in Fig. 11, the first strain detection element 61A and the second strain detection element 61B are arranged at positions (rotationally symmetrical positions) opposing each other with the center axis X2 interposed therebetween on the upper surface 52B1 of the protruding portion 52B of the strain generation body 52. The first strain detection element 61A is arranged at a position on the rear side (negative side of the Y axis) of the center axis X2, and the second strain detection element 61B is arranged at a position on the front side (positive side of the Y axis) of the center axis X2.

[0126] In addition, as Figure 11BAs shown, a first groove portion 56A that is annular with a center axis X2 as a center and a plurality of (eight in the example shown) second groove portions 56B that extend linearly in a radial direction from the center axis X2 are formed in the bottom surface 52B2 of the strain generator 52. The groove portions (the first groove portion 56A and the second groove portions 56B) are in a groove shape that is recessed toward the upper surface 52IB side of the protruding portion 52B in the protruding portion 52B. Figure 11B In the example shown, there are eight second groove portions 56B at intervals of 45°. The groove portions (the first groove portion 56A and the second groove portions 56B) are in a groove shape that is recessed toward the upper surface 52IB side of the protruding portion 52B in the protruding portion 52B.

[0127] Also, as shown, the first strain detection element 61A and the second strain detection element 61B are each disposed at a position that opposes the intersection of the first groove portion 56A and the second groove portion 56B in the upper surface 52IB of the protruding portion 52B. Figure 11B

[0128] These disposed positions are positions in which greater negative strain (strain in the tensile direction) is generated in each of the first strain detection element 61A and the second strain detection element 61B when a fastening axial force is applied to the strain generator 52 in the axial direction of the center axis X2, which was discovered by the inventors of the present application through simulation.

[0129] Note that the strain detection elements 61A, 61B can be disposed in the upper surface 52IB of the protruding portion 52B by various disposition methods.

[0130] For example, the strain detection elements 61A, 61B can also be directly attached to the upper surface 52IB of the protruding portion 52B by an adhesive or the like. In this case, since the disposed surface is a flat surface, the strain detection elements 61A, 61B can also be easily and reliably disposed in the prescribed disposed positions in the upper surface 52IB.

[0131] In addition, for example, the strain detection elements 61A, 61B can also be formed in the upper surface 52IB by printing a metal ceramic or a composite resistor in which an adhesive is a synthetic resin on the upper surface 52IB of the protruding portion 52B. In this case, the strain detection elements 61A, 61B can also be easily and reliably disposed in the prescribed disposed positions in the upper surface 52IB. In particular, in the case of printing, since the printing, drying, and curing of the strain detection elements 61A, 61B can be performed collectively for a plurality of strain generators 52 in a state in which the plurality of strain generators 52 are arranged side by side, the strain detection elements 61A, 61B can be easily and reliably disposed in the plurality of strain generators 52.

[0132] ​Further, for example, the strain detection elements 61A, 61B can also be attached to the upper surface 52B1 of the protruding portion 52B in a state of being mounted to a rigid substrate or a flexible substrate, together with the rigid substrate or the flexible substrate. In this case, since the arrangement surface is a flat surface, the strain detection elements 61A, 61B can also be easily and reliably arranged at a predetermined arrangement position in the upper surface 52B1.

[0133] (Configuration of the bridge circuit 70)

[0134] Figure 12 is a circuit diagram of the bridge circuit 70 provided in the detection body 50 of the second embodiment. As shown in Figure 12 , the bridge circuit 70 is configured to include the strain detection elements 61A, 61B and the resistors R1, R2.

[0135] In the bridge circuit 70 shown in Figure 12 , the strain detection elements 61A, 61B have resistance values that decrease as the fastening axial force in the axial direction of the center axis X2 of the strain generating body 52 increases.

[0136] Therefore, in the bridge circuit 70, the voltage value Vp at the connection point at which the strain detection element 61B is connected to the resistor R2 increases as the fastening axial force in the axial direction of the center axis X2 of the strain generating body 52 increases. Further, the voltage value Vn at the connection point at which the strain detection element 61A is connected to the resistor R1 decreases as the fastening axial force in the axial direction of the center axis X2 of the strain generating body 52 increases.

[0137] The bridge circuit 70 outputs a voltage difference between the voltage value Vp and the voltage value Vn by a differential amplifier (omitted from illustration) amplifying the voltage difference. Thus, the bridge circuit 70 can output a strain detection signal whose voltage value increases as the fastening axial force in the axial direction of the center axis X2 of the strain generating body 52 increases.

[0138] Note that the fastening torque of the fastening member and the fastening axial force in the axial direction of the center axis X2 of the strain generating body 52 are in a proportional relationship with each other. That is, as the fastening torque of the fastening member increases, the fastening axial force in the axial direction of the center axis X2 of the strain generating body 52 increases. Thus, the bridge circuit 70 can output a strain detection signal whose voltage value increases as the fastening torque of the fastening member increases.

[0139] (Example of dimensions of each portion of the detection body 50)

[0140] Figure 13 is a diagram showing an example of dimensions of each portion of the detection body 50 of the second embodiment. Figure 13 shows an example of dimensions of each portion of the detection body 50 in a case where the detection body 50 is used for installation to a bolt shaft having a diameter of 8 mm. In this example, the dimensions of each portion of the detection body 50 are set so that the strain detection signal output from the bridge circuit 70 is within a range of 0 to 5 V when the fastening torque of the fastening member is within a range of 0 to 20 Nm.Figure 13 In the example shown, the lateral width (width in the X-axis direction) of the detection body 50 is 30 mm. In addition, the diameter of the base portion 52A of the strain generator 52 is 18 mm. In addition, the up-and-down width (width in the Z-axis direction) of the detection body 50 is 7 mm.

[0141] (Usage example of detection body 50)

[0142] Figure 14 is a view showing a usage example of the detection body 50 of the second embodiment. Figure 14 Indicates an example in which the flat fastened member 43 is threadedly fastened and fixed to the mounting surface 41 by the nut 42B.

[0143] In Figure 14 In the example shown, the detection body 50 is provided between the nut 42B and the fastened member 43. The bolt shaft 42A extending upward from the mounting surface 41 penetrates the base portion 52A of the strain generator 52 of the detection body 50 and the fastened member 43. The tip portion (end portion on the negative side of the Z-axis) of the bolt shaft 42A is fixed to the mounting surface 41. The nut 42B is threadedly tightened with respect to the bolt shaft 42A from the front end portion (end portion on the positive side of the Z-axis) of the bolt shaft 42A. The nut 42B and the bolt shaft 42A together constitute the fastening mechanism 42.

[0144] In Figure 14 In the example shown, when the nut 42B is threadedly tightened, the fastened member 43 and the detection body 50 are fixed with respect to the mounting surface 41. At this time, the strain generator 52 of the detection body 50 receives the nut 42B on the upper surface 52A1 of the base portion 52A thereof. Thus, the fastening axial force of the bolt shaft 42A in the axial direction (Z-axis direction) is applied to the strain generator 52. Here, the diameter of the upper surface 52A1 is larger than the maximum size (length of the diagonal line) of the nut. Thus, the strain generator 52 can more reliably receive the fastening axial force applied from the nut 42B using the upper surface 52A1 of the base portion 52A thereof.

[0145] As a result, the strain generator 52 generates a strain corresponding to the fastening torque of the nut 42B. The strain generated in the strain generator 52 is detected by the strain detection elements 61A, 61B (refer to Figures 10-12 ) provided in the strain sensing module 60 of the detection body 50, respectively. Also, the bridge circuit 70 (refer to Figure 12) based on the strain detected by each of the strain detection elements 61A, 61B (i.e., the change in the resistance value of each of the strain detection elements 61A, 61B), a strain detection signal corresponding to the tightening torque of the nut 42B is output to the IC 63 provided in the strain detection module 60. The IC 63 outputs the strain detection signal obtained from the bridge circuit 70 to an external device via wireless communication. For example, the external device can determine the tightening state of the nut 42B based on the voltage value indicated by the strain detection signal obtained from the detection body 50.

[0146] Note that, as the output method of the strain detection signal of the strain detection module 60, various output methods can be employed. For example, the strain detection module 60 can generate power using an induction coil when a tag reader covers the strain detection module 60, and wirelessly transmit the strain detection signal to the tag reader using the power. In this case, the strain detection module 60 can be configured not to have a battery and a memory. However, the strain detection module 60 can also be configured to have at least either of a battery and a memory.

[0147] As described above, the detection body 50 of the second embodiment detects the tightening axial force applied by the tightening mechanism 42 in the central axis X2 direction, and includes a strain generator 52 having a through-hole 54 through which a bolt portion of the tightening mechanism 42 is inserted, and a strain detection sensor 61 that detects the strain of the strain generator 52, the strain generator 52 including a block-shaped base portion 52A having the through-hole 54, and a thin plate-shaped protruding portion 52B protruding from the outer side of the base portion 52A in a direction (horizontal direction) orthogonal to the central axis X2 direction, the strain detection sensor 61 being provided to the protruding portion 52B.

[0148] Thus, the detection body 50 of the second embodiment can detect the strain of the strain generator 52 by the strain detection sensor 61 provided to the protruding portion 52B of the strain generator 52, and can also detect slight loosening of the tightening member. Thus, according to the detection body 50 of the second embodiment, the detection accuracy of the strain of the strain generator 52 by the strain detection sensor 61 provided to the protruding portion 52B of the strain generator 52 can be improved.

[0149] In addition, in the detection body 50 of the second embodiment, the protruding portion 52B is provided to the end portion of the bottom surface side of the base portion 52A, and is formed in a gable shape from the outer periphery of the end portion in a direction (horizontal direction) orthogonal to the central axis X2 direction.

[0150] Thus, the detection body 50 of the second embodiment can directly receive the influence on the bottom surface side of the base portion 52A where the strain is large, because the protruding portion 52B is provided on the bottom surface side of the base portion 52A. In particular, the detection body 50 of the second embodiment can receive the strain of the base portion 52A with the entire protruding portion 52B, because the protruding portion 52B is formed in a roof shape so as to surround the outer periphery of the base portion 52A. Thus, the detection body 50 of the second embodiment can reliably transmit the strain of the base portion 52A of the strain generating body 52 to the protruding portion 52B, and can further improve the detection accuracy of the strain of the strain generating body 52 detected by the strain detection sensor 61 provided to the protruding portion 52B of the strain generating body 52.

[0151] In addition, in the detection body 50 of the second embodiment, the bottom surface of the protruding portion 52B has groove portions 56A and 56B recessed toward the upper surface side of the protruding portion 52B, the strain detection sensor 61 is provided to the upper surface 52B1 of the protruding portion 52B, and is disposed at a position opposite to the groove portions 56A and 56B.

[0152] Thus, the detection body 50 of the second embodiment can detect the strain of the strain generating body 52 more reliably, because the strain detection sensor 61 is disposed at a position where the strain is further easily generated in the protruding portion 52B. Thus, according to the detection body 50 of the second embodiment, the detection accuracy of the strain of the strain generating body 52 detected by the strain detection sensor 61 provided to the strain generating body 52 can be further improved.

[0153] In addition, in the detection body 50 of the second embodiment, the strain detection sensor 61 has a first strain detection element 61A and a second strain detection element 61B disposed at positions where the protruding portion 52B is opposite to each other across the center axis X2 of the through-hole 54.

[0154] Thus, the detection body 50 of the second embodiment can detect the strain of the strain generating body 52 at two positions in the horizontal direction in the protruding portion 52B of the strain generating body 52, and thus can detect the strain of the strain generating body 52 with high accuracy. Thus, according to the detection body 50 of the second embodiment, the detection accuracy of the strain of the strain generating body 52 detected by the strain detection sensor 61 provided to the strain generating body 52 can be further improved.

[0155] In addition, in the detection body 50 of the second embodiment, the strain generating body 52 has a planar receiving portion that receives a fastening member of the fastening mechanism 42 on the upper surface 52A1 and around the through-hole 54.

[0156] Thus, the detection body 50 of the second embodiment can more reliably receive the fastening axial force applied from the fastening member by the receiving portion. That is, the fastening state of the fastening member can be more reliably converted into the strain of the strain generating body 52. Thus, according to the detection body 50 of the second embodiment, the detection accuracy of the strain of the strain generating body 52 detected by the strain detection sensor 61 provided to the strain generating body 52 can be further improved.

[0157] In addition, the detection body 50 of the second embodiment is further provided with the IC 63 and the communication antenna 64.

[0158] Thus, the detection body 50 of the second embodiment can externally output the high-accuracy detection data indicating the strain of the strain generating body 52 detected by the strain detection sensor 61 through wireless communication. Thus, according to the detection body 50 of the second embodiment, the detection accuracy of the strain of the strain generating body 52 detected by the strain detection sensor 61 provided to the strain generating body 52 can be improved.

[0159] In addition, in the detection body 50 of the second embodiment, the IC 63 and the communication antenna 64 are provided to the protruding portion 52B.

[0160] Thus, the detection body 50 of the second embodiment can arrange the strain detection sensor 61, the IC 63, and the communication antenna 64 in the protruding portion 52B in a concentrated manner. Thus, according to the detection body 50 of the second embodiment, the detection body 50 can be miniaturized.

[0161] In addition, the detection body 50 of the second embodiment is further provided with the sealing resin 65 that seals the protruding portion 52B.

[0162] Thus, the detection body 50 of the second embodiment can protect the strain detection sensor 61, the IC 63, and the communication antenna 64 in a collective manner by the sealing resin 65. Thus, according to the detection body 50 of the second embodiment, the long life of the above-described plurality of constituent members can be achieved.

[0163] 〔Third Embodiment〕

[0164] (System configuration of detection system 100)

[0165] Figure 15 is a diagram illustrating the system configuration of the detection system 100 of the third embodiment. As Figure 15 indicated, the detection system 100 is configured to include a detection body 120 and a reading device 140.

[0166] The detection body 120 is a device that detects a fastening axial force applied in the axial direction by a fastening mechanism. As Figure 15As shown, the detection body 120 includes a first strain detection sensor 122, a second strain detection sensor 123, and a control circuit 124.

[0167] The first strain detection sensor 122 is disposed on the planar side of the strain generator 121 and detects the strain in the X3 direction of the central axis of the strain generator 121. The first strain detection sensor 122 outputs a first detection value representing the axial strain of the strain generator 121.

[0168] The second strain detection sensor 123 is disposed on the planar side of the strain generator 121 and detects the strain in the radial direction (orthogonal to the central axis X3 direction) of the strain generator 121. The second strain detection sensor 123 outputs a second detection value representing the detected strain in the radial direction of the strain generator 121.

[0169] It should be noted that the first strain detection sensor 122 and the second strain detection sensor 123 have the same temperature characteristics.

[0170] The control circuit 124 has an antenna 124A. The control circuit 124 wirelessly transmits the difference between a first detection value detected by the first strain detection sensor 122 and a second detection value detected by the second strain detection sensor 123 to the reading device 140 via the antenna 124A. Additionally, the control circuit 124 wirelessly transmits the wireless ID of the detector 120 to the reading device 140 via the antenna 124A.

[0171] The reading device 140 is a device that obtains various information from the detection body 120. For example... Figure 15 As shown, the reading device 140 includes a main body 140A and a cover 140B.

[0172] Cover 140B is a container-shaped component configured to cover the top of the detector 120 and have an open bottom surface when acquiring various information from the detector 120 (see reference). Figure 16 The cover 140B includes an antenna 141A and a radiation thermometer 144. The antenna 141A receives various information wirelessly transmitted from the detector 120 (the difference between a first and a second detection value, and a wireless ID). The radiation thermometer 144 non-contactly measures the temperature of the detector 120. Furthermore, the radiation thermometer 144 outputs the thermometer reading representing the measured temperature of the detector 120.

[0173] The main body 140A and the cover 140B are provided independently. The main body 140A has a communication unit 141 and a control unit 143. As the main body, for example, a PC (Personal Computer) is used, but it is not limited to this.

[0174] The communication section 141 is connected to the antenna 141A provided to the cover 140B. The communication section 141 receives various information (the difference value between the first detection value and the second detection value, and the wireless ID) wirelessly transmitted from the detection body 120 via the antenna 141A. Specifically, the communication section 141 transmits an electric wave in accordance with the protocol of the wireless ID to the detection body 120 via the antenna 141A. The control circuit 124 of the detection body 120 generates power for driving the sensor and the IC by receiving the signal transmitted from the communication section 141. The control circuit 124 of the detection body 120 transmits various information (the difference value between the first detection value and the second detection value, and the wireless ID) to the reading device 140 using a reflected wave with respect to the electric wave from the reading device 140. Thus, the communication section 141 of the reading device 140 receives various information (the difference value between the first detection value and the second detection value, and the wireless ID) transmitted from the detection body 120 via the antenna 141A. Note that, in the present embodiment, the wireless communication frequency of the reading device 140 and the detection body 120 uses the 920 MHz band, but other frequency bands can also be used.

[0175] The control section 143 performs various controls in the reading device 140. For example, the control section 143 performs acquisition of various information (the difference value between the first detection value and the second detection value, the wireless ID, and the temperature measurement value), temperature correction of data acquired from the detection body 120, loosening determination of the fastening member based on data acquired from the detection body 120, notification of the loosening determination result to the operator, recording of the loosening determination result, and transmission and reception of various information with an external device (for example, a server or the like).

[0176] (Structure of Detection Body 120)

[0177] Figure 16 is a perspective view showing the appearance of the upper surface side of the detection body 120 of the third embodiment. Figure 16 The detection body 120 shown is a device having a substantially cylindrical strain generator 121. The detection body 120 is disposed between the fastening member (screw or nut) and the fastened member when the fastening member is threadedly fastened and fixed to a prescribed mounting surface (for example, a wall surface), and thus can detect a fastening axial force applied in the axial direction of the central axis X3 by the fastening of the fastening member.

[0178] As shown in Figure 16 , the detection body 120 includes the strain generator 121, the first strain detection sensor 122, the second strain detection sensor 123, the control circuit 124, and the housing 126.

[0179] The strain generator 121 is a block-shaped component with a generally cylindrical shape. The strain generator 121 is preferably formed using a metallic raw material such as stainless steel. A through hole 121A is formed at the center of the strain generator 121, extending through it in the vertical direction (Z-axis direction) along the central axis X3. The through hole 121A is for the bolt portion of the fastening mechanism to be inserted.

[0180] In addition, such as Figure 16 As shown, the upper surface 121B of the strain generator 121 is planar. Thus, the upper surface 121B of the strain generator 121 functions as a planar receiving portion for receiving fastening components (bolts or nuts).

[0181] In addition, such as Figure 16 As shown, four planar portions 121C are formed at 90° intervals on the outer peripheral surface of the strain generator 121. One pair of planar portions 121C sandwiches the through hole 121A in the middle, and are parallel to each other and both parallel to the YZ plane. Another pair of planar portions 121C sandwiches the through hole 121A in the middle, and are parallel to each other and both parallel to the XZ plane. The four planar portions 121C are formed, for example, by removing a portion of the outer peripheral surface of the pre-processed strain generator 121, which has a cylindrical shape, parallel to the XZ or YZ plane.

[0182] The first strain detection sensor 122 is disposed on one of the four planar portions 121C of the strain generator 121. The first strain detection sensor 122 detects the strain in the X3 direction of the central axis of the strain generator 121 as a first detection value and outputs the first detection value to the control circuit 124. For example, the first strain detection sensor 122 is configured relative to the planar portion 121C in such a way that a normal strain (strain in the compression direction) is generated in the strain detection element.

[0183] The second strain detection sensor 123 is disposed on another plane portion 121C of the four plane portions 121C of the strain generating body 121. The second strain detection sensor 123 detects the strain in the radial direction of the strain generating body 121 as a second detection value and outputs this second detection value to the control circuit 124. For example, the second strain detection sensor 123 is configured relative to the plane portion 121C in a manner that generates negative strain (strain in the tensile direction) in the strain detection element. It should be noted that the second strain detection sensor 123 can be a sensor without flexibility and with fixed resistance. Furthermore, in Figure 16 In the example shown, four planar portions 121C are formed on the outer peripheral surface of the strain-generating body 121, but this is not a limitation. For example, as... Figure 24 as well as Figure 25As shown, it is also possible to form a planar portion 121C on the outer peripheral surface of the strain generating body 121, and to configure two strain detection sensors 122 and 123 on the planar portion 121C.

[0184] The control circuit 124 is located on the outer side of the outer peripheral surface of the strain generator 121, and is disposed within the first cavity 126B of the housing 126. The control circuit 124 includes an antenna 124A (see reference). Figure 15 Examples of such devices include IC124B. The control circuit 124 wirelessly transmits the difference between the first detection value output from the first strain detection sensor 122 and the second detection value output from the second strain detection sensor 123 to the reading device 140 via antenna 124A. Additionally, the control circuit 124 wirelessly transmits the wireless ID of the detection element 120 stored in the memory of the control circuit 124 to the reading device 140 via antenna 124A.

[0185] It should be noted that the first detection value includes an error component caused by the temperature of the first strain detection sensor 122, and the second detection value includes an error component caused by the temperature of the second strain detection sensor 123. The first strain detection sensor 122 and the second strain detection sensor 123 have the same temperature characteristics, therefore the error components of the first and second detection values ​​are identical. The control circuit 124 wirelessly transmits the difference between the first and second detection values ​​to the reading device 140, thereby enabling the wireless transmission of the detection value after removing the error components of both signals to the reading device 140. However, this is not a limitation; the control circuit 124 may also wirelessly transmit both the first and second detection values ​​to the reading device 140. In this case, the control unit 143 of the reading device 140 may also calculate the difference between the first and second detection values.

[0186] The shell 126 is an annular component that expands radially outward from the outer peripheral surface of the strain generator 121 and surrounds the outer peripheral surface of the strain generator 121. It should be noted that... Figure 16In the present embodiment, the state in which the cover portion of the case 126 has been removed is indicated. The case 126 has an inner cylindrical portion 126A that penetrates the case 126 in the up-down direction. The case 126 is integrated with the strain generator 121 by embedding the strain generator 121 in the inner cylindrical portion 126A. The case 126 is formed, for example, by injection molding of a resin raw material. The case 126 has a first hollow portion 126B and a second hollow portion 126C. The control circuit 124 is disposed in the first hollow portion 126B. Other control circuits can be disposed in the second hollow portion 126C by addition. In the third embodiment, for example, the detection body 120 wirelessly transmits both the difference value and the wireless ID using the control circuit 124. This is not limiting, and the detection body 120 can also be configured to wirelessly transmit either of the difference value and the wireless ID using other control circuits disposed in the second hollow portion 126C.

[0187] (Structure of cover 140B)

[0188] Figure 17 is a diagram showing the structure of the cover 140B provided in the reading device 140 of the third embodiment. As shown in Figure 17 , the cover 140B is a container-like member having a bottom surface opening that covers the upper side and the side of the detection body 120 when various information is acquired from the detection body 120 (i.e., when the fastening state of the fastening member is checked). The antenna 141A and the radiation thermometer 144 are provided on the top surface 140Bb of the cover 140B. The antenna 141A is provided at a position opposite the control circuit 124 of the detection body 120 and receives various information (the difference value of the first detection value and the second detection value and the wireless ID) wirelessly transmitted from the control circuit 124. The radiation thermometer 144 is provided at a position opposite the upper surface of the detection body 120 and irradiates infrared rays or visible light rays to the upper surface of the detection body 120, thereby measuring the temperature of the detection body 120. Further, the radiation thermometer 144 outputs a thermometer value indicating the measured temperature to the main body 140A.

[0189] The reading device 140 of the third embodiment can measure the temperature of the position close to the sensors 122 and 123 by directly measuring the temperature of the detection body 120 using the radiation thermometer 144, compared to the case where the temperature of the bolt is measured. In addition, the reading device 140 of the third embodiment can make the antenna 141A closer to the control circuit 124 by directly measuring the temperature of the detection body 120 using the radiation thermometer 144, compared to the case where the temperature of the bolt is measured, and thus can further improve the communication accuracy between the antenna 141A and the control circuit 124. However, this is not limiting, and it is also possible to measure the temperature of the bolt using the radiation thermometer 144.

[0190] The cover 140B is formed using a metallic raw material (such as aluminum or iron) that is difficult for radio waves to pass through, in order to prevent radio waves from leaking to the outside. Furthermore, sheet-like radio wave absorbers 145 are attached to the entire surface of the top plate 140Bb and the inner wall 140Bc exposed in its internal space 140Ba, to further prevent radio wave leakage to the outside. Conductive radio wave absorbing materials, dielectric radio wave absorbing materials, magnetic radio wave absorbing materials, etc., are used as the radio wave absorbers 145. Thus, the cover 140B becomes a structure that prevents radio waves from leaking to the outside, thereby preventing false detection of radio waves transmitted from other detectors 120 even when multiple detectors 120 are placed close together.

[0191] (Structure of control circuit 124)

[0192] Figure 18 This is a diagram showing the structure of the control circuit 124 included in the detection body 120 of the third embodiment.

[0193] like Figure 18 As shown, a first strain detection sensor 122 and a second strain detection sensor 123 are provided on the outer peripheral surface of the strain generator 121. The strain generator 121, which has a washer shape, is fastened by a fastening member (bolt or nut), thereby contracting along the central axis X3 and elongating along the radial direction. The ratio of contraction to elongation of the strain generator 121 is determined according to the Poisson's ratio of the material used in the strain generator 121 and the shape of the strain generator 121.

[0194] At this time, the first strain detection sensor 122 contracts together with the strain generating body 121, thereby reducing its resistance and detecting the strain in the X3 direction of the central axis of the strain generating body 121. Meanwhile, the second strain detection sensor 123 extends together with the strain generating body 121, thereby increasing its resistance and detecting the strain in the radial direction (orthogonal to the X3 direction) of the strain generating body 121. It should be noted that the second strain detection sensor 123 can also be a sensor without flexibility and with a fixed resistance.

[0195] The first detection value output from the first strain detection sensor 122 to the control circuit 124 and the second detection value output from the second strain detection sensor 123 to the control circuit 124 are opposite in sign to each other.

[0196] Furthermore, the first strain detection sensor 122 and the second strain detection sensor 123 have the same temperature characteristics. Therefore, the first detection value output from the first strain detection sensor 122 and the second detection value output from the second strain detection sensor 123 contain the same error component caused by the influence of temperature.

[0197] Additionally, as inFigure 18 As exemplified in FIG. 12, the control circuit 124 has a first detection circuit 1801 that outputs a first detection value by driving the first strain detection sensor 122, a second detection circuit 1802 that outputs a second detection value by driving the second strain detection sensor 123, and a differential circuit 1803, and is capable of outputting, with the differential circuit 1803, a difference value between the first detection value output from the first detection circuit 1801 and the second detection value output from the second detection circuit 1802.

[0198] Further, as exemplified in FIG. 12, the control circuit 124 has an ID generation circuit 1804, and is capable of outputting, with the ID generation circuit 1804, the wireless ID of the detection body 120 saved in the control circuit 124. Figure 18

[0199] Further, the control circuit 124 has a rectification circuit 1805, a transmission circuit 1806, and an antenna 124A, and is capable of wirelessly transmitting, via the antenna 124A, the difference value between the first detection value and the second detection value and the wireless ID of the detection body 120 to the reading device 140.

[0200] Thus, the control circuit 124 is capable of wirelessly transmitting, to the reading device 140, the detection value of the sum of the change component of the strain of the central axis X3 direction of the strain generation body 121, from which the common component (error, noise, and the like caused by the influence of temperature) of the two sensors 122 and 123 is removed, and the change component of the strain of the radial direction of the strain generation body 121.

[0201] Note that, in the present embodiment, as the control circuit 124, an IC having an interface for a sensor is used. Thus, the control circuit 124 is capable of transmitting not only the wireless ID but also the difference value between the first detection value and the second detection value.

[0202] Further, the control circuit 124 is capable of generating power by receiving an electric wave sent from the reading device 140, and is capable of driving the sensors 122 and 123 and the control circuit 124 with the power. That is, the control circuit 124 is capable of operating even without mounting a battery, and does not need maintenance related to the battery such as battery replacement, charging, and the like.

[0203] (Structure of Control Circuit 124)

[0204] Figure 19 is a flowchart showing the operation sequence of the detection body 120 of the third embodiment.

[0205] ​First, in the process of producing the detection body 120, data for correction (slope of sensor output with respect to applied load, sensor output with respect to temperature environment) is measured. And, these measured values are associated with the wireless ID of the detection body 120 (step S1901).

[0206] Next, from the measured values (temperature, strain sensor values) and the wireless ID of the detection body 120 and the data at the time of the process of producing the detection body 120, correction data and a correction table are produced and saved in the reading device 140 (step S1902).

[0207] Next, when the fastening work of the bolt is completed, the reading device 140 is brought close to the detection body 120, and data measurement (temperature, strain sensor values) after the fastening work and ID recognition are performed. In addition, initial looseness determination is performed (step S1903).

[0208] Next, at the time of inspection, the reading device 140 is brought close to the detection body 120, and temperature, sensor values, and wireless ID are read (step S1904).

[0209] Next, from the measured values (temperature, strain sensor values), the wireless ID, and the correction data and the correction table, comparison with the bolt looseness threshold value is performed (step S1905). Then, it is determined whether the determination result is "OK" (step S1906).

[0210] In the case where it is determined in step S1906 that the determination result is not "OK" (step S1906: No), correction implementation such as reinforcement fastening is implemented (step S1907). And, the work returns to step S1904.

[0211] In the case where it is determined in step S1906 that the determination result is "OK" (step S1906: Yes), the measured result is saved (step S1908). And, the series of work illustrated in FIG. 8 ends. Figure 19

[0212] Hereinafter, the work order of the detection body 120 will be described in more detail. Figure 19

[0213] <Production of detection body 120>

[0214] (1) After assembling the sensor module, apply zero load and rated load at a constant temperature;

[0215] (2) Record the sensor output at that time;

[0216] (3) Produce offset correction data from the sensor output of the zero load;

[0217] ​​(4) Create slope correction data from sensor outputs at zero load and rated load;

[0218] (5) Create temperature correction data from representative temperature characteristics of strain gauges in the sensor;

[0219] (6) Change temperature and perform (1) to (4);

[0220] (7) Associate each correction data with the wireless ID of the test object 120;

[0221] (8) Save the correction data in the main body 140A of the reading device 140.

[0222] At the time of tightening of the bolt

[0223] (1) After performing work on the bolt, module, and nut, cover the cover 140B of the reading device 140;

[0224] (2) Fix in such a manner that the focal point of the radiation thermometer 144 is positioned at the test object 120 (use shape guidance);

[0225] (3) Measure the temperature of the test object 120 using the radiation thermometer 144;

[0226] (4) Record the sensor output after the work;

[0227] (5) Associate each data with the wireless ID of the test object 120.

[0228] At the time of loose check at the site

[0229] (1) Cover the bolt with the cover 140B of the reading device 140;

[0230] (2) Fix in such a manner that the focal point of the radiation thermometer 144 is positioned at the test object 120 (use shape guidance);

[0231] (3) Measure the temperature of the test object 120 using the radiation thermometer 144;

[0232] (4) Read the wireless ID and sensor information of the test object 120 using the electric wave from the reading device 140;

[0233] (5) Correct the sensor output from the data of the radiation thermometer 144, the wireless ID of the test object 120, and the information at the time of work;

[0234] (6) Perform good / bad determination.

[0235] (Necessity of temperature correction)

[0236] Here, the necessity of temperature correction of the resistance change type strain sensor will be described. As the resistance change type strain sensor, for example, a metal thin film method (CuNi, NiCr, etc.), a piezoelectric method in which silicon is doped with an impurity, and the like can be listed. The resistance value of the strain detection element changes according to a slight length change (strain) of the strain detection element, and thus strain detection is performed.

[0237] The resistance value change ΔR of the resistance change type strain sensor is affected by temperature, and is generally given by the following mathematical expression (1).

[0238] ΔR = resistance value change by strain + resistance value change of strain gauge material by temperature + resistance value change of strain coefficient by temperature (1)

[0239] In mathematical expression (1), the resistance value change of the strain gauge material by temperature and the resistance value change of the strain coefficient by temperature are characteristics that are nonlinear with respect to temperature, and there is a case where a large influence on the original resistance change value by strain occurs when the temperature difference is large. Therefore, in order to accurately measure strain, correction with respect to temperature is required.

[0240] For example, in the following mathematical expression (2), in the case of a metal thin film (CuNi, NiCr, etc.), the strain coefficient K is "2.1", the resistance change coefficient of the strain gauge material by temperature TCR is "14 ppm / °C", and the temperature coefficient of the strain coefficient TCGF is "-300 ppm / °C".

[0241] ΔR = R * |ε + TCR * Δt| * K * (1 + TCGF * Δt) (2)

[0242] In mathematical expression (2), the meanings of the respective symbols are as follows.

[0243] ΔR: amount of change in resistance value of strain sensor

[0244] R: resistance value of strain sensor

[0245] ε: strain

[0246] TCR: resistance change coefficient of strain gauge material by temperature

[0247] Δt: temperature change (°C)

[0248] K: strain coefficient of strain sensor

[0249] TCGF: temperature coefficient of strain coefficient of strain sensor

[0250] For example, in a case where the detection body 120 is fastened with a bolt at a temperature of 25°C, when a change in strain caused by the fastening is set to 200 με, the change in resistance value ΔR is "0.050 Ω" as calculated from the following mathematical expression (3) because Δt = 0.

[0251] ΔR1 = R * ε * K = 120 * 200E-6 * 2.1 = 0.050 Ω (3)

[0252] On the other hand, in a case where the temperature is changed by 50°C in a state where the detection body 120 is fastened with a bolt, the change in resistance value ΔR is changed to "0.223 Ω" as calculated from the following mathematical expression (4).

[0253] ΔR2 = R * (ε + TCR * Δt) * K * (1 + TC GF * Δt)

[0254] = 120 * (200E-6 + 14E-6 * 50) * 2.1 * (1 - 300E-6 * 50)

[0255] = 0.223 Ω (4)

[0256] That is, the difference ΔR2 - ΔR1 of the change in resistance value ΔR in a case where the temperature at the time of laying is 25°C and the temperature is changed by 50°C under direct sunlight in hot weather is 0.173 Ω.

[0257] This is several times larger than the change in resistance value caused by the strain in the absence of a change in temperature, and it is not possible to distinguish between a change caused by the strain and a change caused by the temperature. That is, correction of the influence of the temperature change is required. In particular, a representative characteristic of a semiconductor piezoelectric strain gauge is that TCR is 1300 ppm / °C, K = 100, and TC GF = -2000 ppm / °C, and thus the influence of the temperature is further significant.

[0258] The detection system 100 of the third embodiment is capable of detecting the strain of the strain generating body 121 with high precision by performing temperature correction of the first detection value and the second detection value. Specifically, the detection system 100 outputs the difference between the first detection value and the second detection value from the detection body 120, thereby removing a common component of the first detection value and the second detection value, and thereby performs temperature correction of the first detection value and the second detection value. Furthermore, in the detection system 100, the control section 143 of the reading device 140 corrects the difference between the first detection value and the second detection value (or the first detection value and the second detection value) on the basis of the temperature of the detection body 120 measured by the radiation thermometer 144 and correction data prepared in advance, thereby performing temperature correction of the first detection value and the second detection value.

[0259] (Example of Correction Data)

[0260] Figure 20 is a graph showing an example of correction data for offset correction and slope correction of a sensor value used by the reading device 140 of the third embodiment. Figure 21 is a graph showing an example of correction data for temperature correction of a sensor value used by the reading device 140 of the third embodiment.

[0261] The control section 143 of the reading device 140 of the third embodiment can perform offset correction and slope correction of a sensor value using the correction data shown in Figure 21 . In addition, the control section 143 of the reading device 140 of the third embodiment can perform temperature correction of a sensor value using the correction data shown in Figure 22 .

[0262] For example, the correction data shown in Figure 20 is made by changing a load applied to a sensor from a state where no load is applied to the sensor under a constant temperature, and measuring a sensor value (a measured value) for each of a plurality of loads, thereby making a correction value (an approximation formula or a correction table) for performing offset correction and slope correction of a sensor value.

[0263] In addition, for example, the correction data shown in Figure 21 is made by changing a temperature of a sensor environment under a condition where a constant load is applied to a sensor, and measuring a sensor value (a measured value) for each of a plurality of environmental temperatures, thereby making a correction value (an approximation formula or a correction table) for performing temperature correction of a sensor value.

[0264] (Example of input-output characteristics of the detection body 120)

[0265] Figure 22 is a graph showing an example of input-output characteristics of the detection body 120 of the third embodiment. In Figure 22 , as an example, for each of the strain generating bodies 121 having a diameter of 10 mm and the strain generating bodies 121 having a diameter of 24 mm, an input load F, a strain ε, a resistance value R of a strain sensor, a strain coefficient K of a strain sensor, and a change amount ΔR of a resistance value of a strain sensor are indicated.

[0266] (Resistance value of the sensor 122, 123 corresponds to a change in strain)

[0267] Figure 23 is a graph showing a change in resistance value of the sensors 122, 123 with respect to a strain of the detection body 120 of the third embodiment. As Figure 23 indicated, with respect to the resistance value of the sensors 122, 123, the resistance value linearly decreases as the amount of strain increases. Among them, Figure 23indicates the resistance value in a case where strain is generated in the direction in which the sensor 122, 123 contracts. In a case where strain is generated in the direction in which the sensor 122, 123 elongates, the resistance value increases linearly with respect to the amount of strain, as opposed to the graph shown in FIG. 6. Figure 23 indicates the resistance value in a case where strain is generated in the direction in which the sensor 122, 123 contracts. In a case where strain is generated in the direction in which the sensor 122, 123 elongates, the resistance value increases linearly with respect to the amount of strain, as opposed to the graph shown in FIG. 6.

[0268] (Modified example of the arrangement position of the sensor 122, 123)

[0269] Figure 24 is a graph showing a first modified example of the arrangement position of the sensor 122, 123 in the strain generator 121 of the third embodiment. Figure 25 is a graph showing a second modified example of the arrangement position of the sensor 122, 123 in the strain generator 121 of the third embodiment.

[0270] In the first modified example shown in FIG. 6, the sensor 122, 123 is arranged in the up-down direction (the direction of the central axis X3) in the same planar portion 121C of the strain generator 121. Figure 24 In the first modified example shown in FIG. 6, the sensor 122, 123 is arranged in the up-down direction (the direction of the central axis X3) in the same planar portion 121C of the strain generator 121.

[0271] Figure 25 In the first modified example shown in FIG. 6, the sensor 122, 123 is arranged in the up-down direction (the direction of the central axis X3) in the same planar portion 121C of the strain generator 121.

[0272] (Evaluation results of the detection body 120)

[0273] Figure 26 is a graph showing the evaluation results of the detection body 120 of the third embodiment.

[0274] In the first modified example shown in FIG. 6, the sensor 122, 123 is arranged in the up-down direction (the direction of the central axis X3) in the same planar portion 121C of the strain generator 121. Figure 26 Figure 24 In the first modified example shown in FIG. 6, the sensor 122, 123 is arranged in the up-down direction (the direction of the central axis X3) in the same planar portion 121C of the strain generator 121.

[0275] In the first modified example shown in FIG. 6, the sensor 122, 123 is arranged in the up-down direction (the direction of the central axis X3) in the same planar portion 121C of the strain generator 121. Figure 26 Figure 25 In the first modified example shown in FIG. 6, the sensor 122, 123 is arranged in the up-down direction (the direction of the central axis X3) in the same planar portion 121C of the strain generator 121.

[0276] In the first modified example shown in FIG. 6, the sensor 122, 123 is arranged in the up-down direction (the direction of the central axis X3) in the same planar portion 121C of the strain generator 121. Figure 26 Figure 16 In the first modified example shown in FIG. 6, the sensor 122, 123 is arranged in the up-down direction (the direction of the central axis X3) in the same planar portion 121C of the strain generator 121. ​​​​

[0277] As shown in the evaluation item "thickness" of Table 1, in the case of Structure A, since the sensor 122 is disposed at the same height position on the side surface of the strain generator 121, the thickness of the strain generator 121 can be reduced. Figure 26 As shown in the evaluation item "thickness" of Table 1, in the case of Structure B and Structure C, since the sensors 122 and 123 can be disposed at the same height position on the side surface of the strain generator 121, the thickness of the strain generator 121 can be reduced.

[0278] As shown in the evaluation item "temperature unevenness" of Table 1, in the case of Structure A and Structure B, since the sensors 122 and 123 can be disposed close to the same planar portion 121C of the strain generator 121, the temperature difference between the sensors 122 and 123 can be suppressed, and temperature correction of both can be performed with high accuracy. Figure 26 As shown in the evaluation item "junction" of Table 1, in the case of Structure A and Structure B, since the sensors 122 and 123 can be disposed close to the same planar portion 121C of the strain generator 121, the distance of the junction of the sensors 122 and 123 and the control circuit 124 can be shortened.

[0279] Figure 26 As shown in the evaluation item "junction" of Table 1, in the case of Structure A and Structure B, since the sensors 122 and 123 can be disposed close to the same planar portion 121C of the strain generator 121, the distance of the junction of the sensors 122 and 123 and the control circuit 124 can be shortened.

[0280] As shown in the evaluation item "adhesion defect" of Table 1, in the case of Structure C, since one sensor can be disposed for each of the two planar portions 121C of the strain generator 121, a large sensor can be disposed, and the adhesion defect of the sensor can be suppressed. Figure 26 As described above, the detection body 120 of the third embodiment detects the fastening axial force applied by the fastening mechanism 150 in the axial direction, and the detection body 120 includes: a strain generator 121 having a through-hole 121A through which a bolt portion 151A of the fastening mechanism 150 is inserted; a first strain detection sensor 122 disposed on a planar side surface of the strain generator 121, i.e., a planar portion 121C, and detecting the strain of the strain generator 121; and a second strain detection sensor 123 disposed on the planar side surface of the strain generator 121, i.e., the planar portion 121C, and detecting the strain of the strain generator 121.

[0281] Thus, the detection body 120 of the third embodiment can use the first detection value of the first strain detection sensor 122 and the second detection value of the second strain detection sensor 123 to remove the common components (errors, noise, and the like caused by the influence of temperature) included in the first detection value and the second detection value. Thus, according to the detection body 120 of the third embodiment, the detection accuracy of the strain of the strain generator 121 detected by the strain gauge disposed on the strain generator 121 can be improved.

[0282]

[0283] ​​In addition, in the detection body 120 of the third embodiment, the first strain detection sensor 122 and the second strain detection sensor 123 have the same temperature characteristics as each other.

[0284] Thus, in the detection body 120 of the third embodiment, since the common components (errors, noise, and the like caused by the influence of temperature) included in the first detection value and the second detection value are substantially the same as each other, the common components can be removed with higher accuracy.

[0285] In addition, in the detection body 120 of the third embodiment, the first strain detection sensor 122 detects the strain in the axial direction of the strain generator 121, and the second strain detection sensor 123 detects the strain in the direction orthogonal to the axial direction of the strain generator 121.

[0286] Thus, in the detection body 120 of the third embodiment, the difference between the first detection value and the second detection value is found, and thus a strain detection value that represents the amount of strain of the strain generator 121 with higher accuracy after the common components included in the first detection value and the second detection value are removed can be found.

[0287] In addition, the detection body 120 of the third embodiment further includes the control circuit 124 that wirelessly transmits the difference between the first detection value and the second detection value to the reading device 140.

[0288] Thus, in the detection body 120 of the third embodiment, a strain detection value that represents the amount of strain of the strain generator 121 with higher accuracy after the common components included in the first detection value and the second detection value are removed can be wirelessly transmitted to the reading device 140.

[0289] In addition, in the detection body 120 of the third embodiment, the control circuit 124 further wirelessly transmits the wireless ID of the detection body 120 to the reading device 140.

[0290] Thus, in the detection body 120 of the third embodiment, the correspondence relationship between the strain detection value obtained from the detection body 120 and the identification information of the detection body 120 can be easily established in the reading device 140.

[0291] In addition, the detection system 100 of the third embodiment includes the detection body 120 and the reading device 140.

[0292] Thus, in the detection system 100 of the third embodiment, the reading device 140 can obtain a strain detection value that represents the amount of strain of the strain generator 121 with higher accuracy from the detection body 120. Thus, according to the detection system 100 of the third embodiment, in the reading device 140, the fastening state of the fastening mechanism 150 can be grasped with higher accuracy.

[0293] In addition, in the detection system 100 of the third embodiment, the reading device 140 has the cover 140B configured to cover the detection body 120 when reading data from the detection body 120.

[0294] Thus, the detection system 100 of the third embodiment can avoid mis-detecting data wirelessly transmitted from other detection bodies 120 when reading data wirelessly transmitted from the detection body 120. In addition, the detection system 100 of the third embodiment can make the shape of the cover 140B match the shape of the detection body 120, and thus can easily perform alignment of the cover 140B with respect to the detection body 120.

[0295] In addition, in the detection system 100 of the third embodiment, the reading device 140 has the antenna 141A that receives the difference value and the wireless ID in the cover 140B configured to cover the detection body 120 at a position opposite the control circuit 124.

[0296] Thus, the detection system 100 of the third embodiment can improve the communication accuracy between the control circuit 124 and the antenna 141A.

[0297] In addition, in the detection system 100 of the third embodiment, the reading device 140 has the radiation thermometer 144 that measures the temperature of the detection body 120 in the cover 140B configured to cover the detection body 120 at a position opposite the detection body 120.

[0298] Thus, the detection system 100 of the third embodiment can measure a temperature closer to the temperature of the sensors 122, 123.

[0299] In addition, in the detection system 100 of the third embodiment, the reading device 140 has the control section 143 that corrects the difference value based on the temperature of the detection body 120 measured by the radiation thermometer 144.

[0300] Thus, the detection system 100 of the third embodiment can calculate a strain detection value that accurately represents the strain amount of the strain generating body 121.

[0301] (Fault determination function)

[0302] The detection system 100 of the third embodiment has a failure determination function of the sensors 122, 123. The ratio of the contraction strain in the center axis X3 direction of the strain generating body 121 to the elongation strain in the radial direction of the strain generating body 121 when a load is applied to the strain generating body 121 in the center axis X3 direction is determined by the Poisson's ratio of the material used in the strain generating body 121 (for example, about 0.3 if it is stainless steel). As long as no large deformation such as plastic deformation occurs in the strain generating body 121, the Poisson's ratio is constant. Therefore, the detection system 100 can determine that "at least either one of the first strain sensing sensor 122 and the second strain sensing sensor 123 has failed (for example, deformation, disconnection, peeling of the adhesive, or the like)" by the failure determination function in a case where the ratio of the first detection value output from the first strain sensing sensor 122 to the second detection value output from the second strain sensing sensor 123 deviates greatly from the prescribed ratio (that is, the Poisson's ratio) (for example, in a case where it is outside the range of 0.2 to 0.4 with respect to the normal value of 0.3). Note that the failure determination function can be provided to the control circuit 124 of the detection body 120 or to the control section of the reading device 140.

[0303] The embodiments of the present application have been described in detail above, but the present application is not limited to these embodiments, and various modifications or changes can be made within the scope of the technical concept of the present application described in the technical scheme.

[0304] For example, in the above use example, a nut is used as the fastening member, but the present application is not limited thereto, and a bolt can be used as the fastening member.

[0305] In addition, for example, in the above first embodiment, four strain detection elements 21A to 21D are provided to the flat portion 16A, but the present application is not limited thereto, and for example, three or less or five or more strain detection elements can be provided to the flat portion 16A. For example, the strain detection elements 21A, 21B can be provided to the flat portion 16A, and the strain detection elements 21C, 21D can not be provided. In addition, for example, the strain detection elements 21C, 21D can be provided to the flat portion 16A, and the strain detection elements 21A, 21B can not be provided. In addition, a structure in which strain elements are provided to both the flat portions 16A and 16B can be used.

[0306] Further, in the first embodiment described above, the structure in which the pair of flat surfaces 16A, 16B is provided is preferable, but is not limited thereto, and for example, the structure in which only one flat surface on the side on which the supply element is provided is provided can be used. Further, in the structure in which the flat surface 16A is formed at a position closer to the center axis Xl than the flat surface 16B, but is not limited thereto, and for example, the structure in which the flat surface 16A and the flat surface 16B are arranged at the same distance from the center axis Xl can be used.

[0307] Further, in the second embodiment described above, the two strain detection elements 61A, 61B are provided on the upper surface 52B1 of the protruding portion 52B, but are not limited thereto, and for example, three or more strain detection elements can be provided on the upper surface 52B1.

[0308] Further, in the first embodiment described above, the strain generating body 12 is provided in a substantially cylindrical shape, but is not limited thereto. For example, the strain generating body 12 can be provided in a prismatic shape having a flat surface on a side surface or the like.

[0309] Further, in the second embodiment described above, the base portion 52A of the strain generating body 52 is provided in a substantially cylindrical shape, but is not limited thereto. For example, the base portion 52A can be provided in a prismatic shape in which the protruding portion is provided on the outer side or the like.

[0310] Further, in the second embodiment described above, the structure in which the protruding portion 52B is formed in a roof shape in the horizontal direction from the outer periphery of the end portion of the bottom surface side of the base portion 52A is preferable, but is not limited thereto, and the protruding portion 52B can be provided to protrude from the outer side (outer peripheral surface) of the base portion 52A in the horizontal direction.

[0311] Further, in the third embodiment described above, as the method of temperature compensation of the sensor detection value, the method in which the difference value between the first detection value and the second detection value is output to the reading device 140 and the method in which the temperature correction is performed in the reading device 140 based on the measurement value of the radiation thermometer 144 are described, but temperature compensation of the sensor detection value can be performed using these techniques as in the following Modification Examples 1 to 3.

[0312] (Modification Example 1)

[0313] For example, the difference value between the first detection value and the second detection value can be output from the detection body 120 to the reading device 140, and the temperature correction can be performed in the reading device 140 based on the measurement value of the radiation thermometer 144 (i.e., the temperature of the detection body 120) on the difference value between the first detection value and the second detection value.

[0314] (Modification Example 2)

[0315] Further, for example, the first detection value and the second detection value can be output from the detection body 120 to the reading device 140, and the first detection value and the second detection value can be temperature-corrected based on the measurement value of the radiation thermometer 144 in the reading device 140.

[0316] (Modified Example 3)

[0317] Further, for example, either of the first strain detection sensor 122 and the second strain detection sensor 123 can be provided in the detection body 120, and the detection value of the one sensor can be output to the reading device 140, and the detection value of the one sensor can be temperature-corrected based on the measurement value of the radiation thermometer 144 in the reading device 140.

[0318] (Fourth Embodiment)

[0319] Figure 27 is an exploded view of the fastening structure 200 of the fourth embodiment. Figure 28 is a view showing the fastened state of the fastening structure 200 of the fourth embodiment.

[0320] As shown in Figure 27 and Figure 28 , the fastening structure 200 of the fourth embodiment threadedly fastens and fixes the fastened member 203 to the mounting surface 201 using a fastening mechanism 200A composed of the nut 206 and the bolt shaft 202.

[0321] As shown in Figure 27 and Figure 28 , the fastening structure 200 has, in order from the mounting surface 201 side (negative side of the Z axis), the mounting surface 201, the bolt shaft 202, the fastened member 203, the strain generator 205, the washer 204, and the nut 206.

[0322] The mounting surface 201 is a flat surface for mounting the fastened member 203. The fastened member 203 is a flat plate-shaped member made of metal and mounted to the mounting surface 201. The fastened member 203 is formed with a through-hole 203A that penetrates the fastened member 203 in the vertical direction. The bolt shaft 202 can be inserted through the through-hole 203A.

[0323] The bolt shaft 202 is a rod-shaped member made of metal and vertically erected with respect to the mounting surface 201 and extending along the central axis X4. A thread (not shown) that can be screwed with the nut 206 is formed on the outer peripheral surface of the bolt shaft 202. The lower end portion of the bolt shaft 202 is fixed to the fastened member 203. The bolt shaft 202 can also penetrate the mounting surface 201.

[0324] The strain generator 205 is a block-shaped member having a substantially thin cylindrical shape. The strain generator 205 is formed of, for example, a metal raw material such as stainless steel. The strain generator 205 can use the same strain generator as the strain generator 12 described in the first embodiment or the strain generator 52 described in the second embodiment, or a strain generator obtained by deforming them. A through-hole 205A that penetrates the strain generator 205 in the up-down direction is formed in the center of the strain generator 205. The bolt shaft 202 can be inserted through the through-hole 205A. The strain generator 205 constitutes the detection body 200B together with a strain detection module 207 that is integrated with the strain generator 205. The strain detection module 207 can use the same strain detection module as the strain detection module 20 described in the first embodiment or the strain detection module 60 described in the second embodiment, or a strain detection module obtained by deforming them. Note that the upper surface of the strain generator 205 is a surface that contacts the lower surface of the washer 204, and a lubricant 208 (grease, oil, or the like) is applied to the upper surface of the strain generator 205.

[0325] The washer 204 is a metal disc-shaped member. The washer 204 is disposed between the strain generator 205 and the nut 206. A through-hole 204A that penetrates the washer 204 in the up-down direction is formed in the center of the washer 204. The bolt shaft 202 can be inserted through the through-hole 204A. The diameter of the washer 204 is preferably larger than either the diameter of the nut 206 or the diameter of the strain generator 205.

[0326] The nut 206 is a metal member that can be screwed with the bolt shaft 202. The outer peripheral surface of the nut 206 is formed in a hexagonal shape. A screw hole 206A that penetrates the nut 206 in the up-down direction is formed in the center of the nut 206. A screw thread (not shown) that can be screwed with the bolt shaft 202 is formed in the inner peripheral surface of the screw hole 206A.

[0327] As Figure 28As shown, the fastening structure 200 thus configured sequentially arranges the fastened member 203, the strain generating body 205, and the washer 204 from the mounting surface 201 side between the mounting surface 201 and the nut 206, and in a state where the bolt shaft 202 is inserted through the fastened member 203, the strain generating body 205, and the washer 204, respectively, the nut 206 is screwed to the bolt shaft 202, thereby fixing the fastened member 203, the strain generating body 205, and the washer 204 with respect to the mounting surface 201. At this time, the strain generating body 205 is applied with a fastening axial force in the axial direction (Z-axis direction) of the bolt shaft 202, thereby generating a strain corresponding to the fastening torque of the nut 206. The strain generated in the strain generating body 205 is detected by the strain detection module 207. The strain detection module 207 outputs a strain detection signal indicating a voltage value corresponding to the detected strain to an external device via wireless communication. For example, the external device can determine the fastening state of the nut 206 based on the voltage value indicated by the strain detection signal acquired from the strain detection module 207.

[0328] Here, the fastening structure 200 of the fourth embodiment is able to more accurately reflect the strain generated in the strain generating body 205 as the fastening torque of the nut 206 by providing the washer 204 between the strain generating body 205 and the nut 206, as compared with a structure in which the washer 204 is not provided. Thus, the fastening structure 200 of the fourth embodiment is able to determine the fastening torque of the nut 206 with higher accuracy based on the strain detection signal.

[0329] (Comparative Example)

[0330] Here, the comparative example of the fastening structure 200 of the fourth embodiment will be described with reference to Figures 29-32 The comparative example of the fastening structure 200 of the fourth embodiment will be described. In the comparative example, the inventors alternately performed a nut 206 fastening operation and a nut 206 loosening operation with respect to a case where the washer 204 is provided to the fastening structure 200 and a case where the washer 204 is not provided to the fastening structure 200, and measured a change in the amount of strain generated in the strain generating body 205.

[0331] Note that the implementation conditions of the comparative example are as follows.

[0332] Size of the bolt shaft 202: M24;

[0333] Material of the bolt shaft 202: SUS304;

[0334] Material of the nut 206: SUS304;

[0335] Material of the washer 204: SUS304;

[0336] Thickness of the washer 204: 4 mm;

[0337] Tightening torque of nut 206: 400 Nm (first time), 200 Nm (second time).

[0338] Figure 29 as well as Figure 30 This is a graph showing the measurement results of the strain of the strain generator 205 in the fastening structure 200 of the fourth embodiment (without the washer 204). Figure 29 The results of the first measurement are shown. Figure 30 The results of the second measurement are shown.

[0339] like Figure 29 as well as Figure 30 As shown, when the washer 204 is not provided in the fastening structure 200, the strain of the strain generator 205 is relatively small when the nut 206 is tightened. This is because, without the washer 204 provided in the fastening structure 200, the lower surface of the nut 206 directly abuts against the upper surface of the strain generator 205, thereby creating engagement between the lower surface of the nut 206 and the upper surface of the strain generator 205, reducing the tightening axial force applied to the strain generator 205.

[0340] Figure 31 as well as Figure 32 This is a graph showing the measurement results of the strain of the strain generator 205 in the fastening structure 200 (in the case where the washer 204 is provided) according to the fourth embodiment. Figure 31 The results of the first measurement are shown. Figure 32 The results of the second measurement are shown.

[0341] like Figure 31 as well as Figure 32 As shown, when the fastening structure 200 is equipped with a washer 204, the strain of the strain generator 205 is relatively large when the nut 206 is tightened. This is because, when the fastening structure 200 is equipped with a washer 204, the washer 204 is sandwiched between the lower surface of the nut 206 and the upper surface of the strain generator 205, making it difficult to achieve engagement between the lower surface of the nut 206 and the upper surface of the strain generator 205, and making it difficult to reduce the tightening axial force applied to the strain generator 205.

[0342] It should be noted that the fastening structure 200 of the fourth embodiment has the following structure, which makes it more difficult to generate engagement between the lower surface of the nut 206 and the upper surface of the strain generator 205.

[0343] • Lubricant 208 is coated on the upper surface of the strain generator 205.

[0344] • The hardness of the 204 washer is greater than that of the 206 nut.

[0345] • The upper surface and the lower surface of the washer 204 are smoothed.

[0346] However, the fastening structure 200 of the fourth embodiment can also have the following structure, in which case it is also more difficult for the lower surface of the nut 206 to bite into the upper surface of the strain generator 205.

[0347] • The lower surface of the nut 206 is coated with a lubricant 208.

[0348] • The upper surface of the washer 204 is coated with a lubricant 208.

[0349] • The lower surface of the washer 204 is coated with a lubricant 208.

[0350] Note that the fastening structure 200 of the fourth embodiment can also be configured to fasten the head of a bolt instead of the nut 206, in which case a washer 204 can also be provided between the head of the bolt and the strain generator 205.

[0351] This international application is based on Japanese Patent Application No. 2020-049851, filed on March 19, 2020, and Japanese Patent Application No. 2020-058466, filed on March 27, 2020, and claims priority thereto, and the entire contents of which are incorporated into this international application.

[0352] Explanation of Reference Signs

[0353] 10, 50 detection body; 12, 52 strain generator; 14, 54 through-hole; 16A, 16B flat portion; 18 pedestal portion; 1SA, 52A1 upper surface (mounting portion); 20, 60 strain detection module; 21, 61 strain detection sensor; 21A, 61A first strain detection element; 21B, 61B second strain detection element; 21C third strain detection element; 21D fourth strain detection element; 22, 62 wiring pattern; 23, 63 IC control circuit); 24, 64 communication antenna; 25, 65 sealing resin; 30 bridge circuit; 41 mounting surface; 42 fastening mechanism; 42A bolt shaft; 42B nut; 43 fastened member; 52A base portion; 52B protruding portion; 52B1 upper surface; 56A first groove portion; 56B second groove portion; R1, R2 resistor; X1, X2 center axis; 100 detection system; 120 detection body; 121 strain generator; 121A through-hole; 121B upper surface; 121C flat portion; 122 first strain detection sensor; 123 second strain detection sensor; 124 control circuit; 124A antenna; 126 housing; 126A inner cylindrical portion; 126B first hollow portion; 126C second hollow portion; 140 reading device; 140A main body; 140B cover; 141 communication portion; 141A antenna; 143 control portion; 144 radiation thermometer; 150 fastening mechanism; 151A bolt portion; 200 fastening structure; 201 mounting surface; 202 bolt shaft; 203 fastened member; 205 strain generator; 204 washer; 206 nut; 207 strain detection module; 208 lubricant; X3, X4 center axis.

Claims

1. A detection body that detects a tightening axial force applied by a tightening mechanism in an axial direction, characterized by comprising: a strain generating body that has a through-hole through which a bolt portion possessed by the tightening mechanism is inserted; and a strain sensing sensor that senses a strain of the strain generating body, wherein the strain generating body is formed in a block shape and has a flat surface portion on a side surface in the axial direction, the strain sensing sensor has a first strain detection element and a second strain detection element arranged in a first direction orthogonal to the axial direction on the flat surface portion, the first strain detection element and the second strain detection element are arranged on a bottom surface side of the strain generating body and sandwich the center axis of the through-hole, the first strain detection element is disposed at a position overlapping with a left end position of an inner peripheral surface of the through-hole, the second strain detection element is disposed at a position overlapping with a right end position of the inner peripheral surface of the through-hole, the strain sensing sensor further has a third strain detection element and a fourth strain detection element arranged in a second direction along the axial direction on the flat surface portion, the third strain detection element and the fourth strain detection element are disposed at positions overlapping with the center axis of the through-hole when the flat surface portion is viewed from above, and the third strain detection element and the fourth strain detection element are disposed at positions farther from the bottom surface side than the first strain detection element and the second strain detection element.

2. The detection body according to claim 1, characterized by further comprising a control circuit and a communication antenna.

3. The detection body according to claim 2, characterized in that the control circuit and the communication antenna are disposed on the flat surface portion.

4. The detection body according to claim 1, characterized by further comprising a sealing resin that seals the flat surface portion.

5. A detection body that detects a tightening axial force applied by a tightening mechanism in an axial direction, characterized by comprising: a strain generating body that has a through-hole through which a bolt portion possessed by the tightening mechanism is inserted; and a strain sensing sensor that senses a strain of the strain generating body, wherein the strain generating body has a block-shaped base portion that has the through-hole and a thin plate-shaped protruding portion that is disposed protruding from an outer side of the base portion in a direction intersecting the axial direction, a first groove portion that is annular about a center axis of the through-hole and a plurality of second groove portions that extend linearly in a radial direction from the center axis of the through-hole are formed on a bottom surface of the protruding portion, the first groove portion and the second groove portions are in groove shapes that are recessed toward an upper surface side of the protruding portion, and the strain sensing sensor is disposed at a position opposite to an intersection of the first groove portion and the second groove portions on the upper surface of the protruding portion.

6. The detection body according to claim 1 or 5, characterized in that the strain generating body has a flat-shaped receiving portion that receives a tightening member possessed by the tightening mechanism on an upper surface and around the through-hole. ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ 7. The detection body according to claim 5, characterized in that the protruding portion is provided at an end portion of the bottom surface side of the base portion, and is formed in a cornice shape from the outer periphery of the end portion in a direction orthogonal to the axial direction.

8. The detection body according to claim 5, characterized in that the strain detection sensor has a first strain detection element and a second strain detection element disposed at positions opposite each other across the center axis of the through-hole.

9. The detection body according to claim 5, characterized in that the detection body further has a control circuit and a communication antenna.

10. The detection body according to claim 9, characterized in that the control circuit and the communication antenna are provided to the protruding portion.

11. The detection body according to claim 5, characterized in that the detection body further has a sealing resin that seals the protruding portion.

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