JP2017075871A - Force sensor, force detection device using the same, force detection system, and force detection method - Google Patents

Abstract

To reduce the thickness of a force sensor.
A force sensor includes a detection unit, a first structure, a second structure, and an elastic body. The detection unit 20 includes a core 4 made of a magnetic material, and a coil 5 that is magnetically coupled to the core 4. In the detection unit 20, the magnetic flux generated by the coil 5 by energization passes through the core 4. The first structure 21 and the second structure 22 are respectively disposed on both sides of the core 4 in a predetermined detection direction. The elastic body 23 is provided between the outer peripheral edge of the first structure 21 and the outer peripheral edge of the second structure 22, joined to both, and is formed of a material having a lower elastic modulus than the core 4. The detection unit 20 is configured to receive a load applied from the first structure 21 and the second structure 22 in a direction along the detection direction.
[Selection] Figure 1

Description

  The present invention generally relates to a force sensor, a force detection device using the force sensor, a force detection system, a force detection method, and more specifically, a force sensor for detecting a load applied to a magnetic body by using an inverse magnetostriction effect of the magnetic body, and The present invention relates to a force detection device, a force detection system, and a force detection method using the same.

  2. Description of the Related Art Conventionally, a load cell (force sensor) that detects a load using a strain gauge (strain gauge) is known. The force sensor described in Patent Document 1 includes a plurality of ring-shaped outer periphery fixing portions in plan view, a load application portion located at the center inside the outer periphery fixing portion, and a plurality of outer periphery fixing portions and load application portions. And a strain generating portion. A strain gauge is affixed to each straining portion. Each strain gauge detects a load applied to the load application unit and converts it into an electrical signal.

Japanese Utility Model Publication No. 6-74942

  However, since the conventional example is configured to detect a load when the strain gauge is deformed together with the strain generating portion, it is necessary to provide the strain generating portion by processing a plate-like member (plate). For this reason, in the above conventional example, there is a problem in that it is difficult to reduce the thickness of the force sensor because a plate having a thickness capable of designing the strain generating portion is required.

  The present invention has been made in view of the above points, and an object thereof is to reduce the thickness of a force sensor.

  A force sensor according to a first aspect includes a core formed of a magnetic material, and a coil that is magnetically coupled to the core, and a magnetic flux generated by the coil when energized passes through the core; and the core And a first structure and a second structure respectively disposed on both sides in a predetermined detection direction, and provided between and joined to the outer periphery of the first structure and the outer periphery of the second structure. And an elastic body formed of a material having a lower elastic modulus than the core, and the detection unit receives a load applied from the first structure body and the second structure body in a direction along the detection direction. It is comprised by this.

  In the first embodiment, the force sensor according to the second aspect preferably further includes a suppression structure that suppresses relative rotation of the first structure and the second structure around the axis along the detection direction. .

  In the force sensor of the third form, in the second form, as the restraining structure, the first structure and the second structure may each be formed in a non-circular shape when viewed from the detection direction. preferable.

  In the force sensor according to the fourth aspect, in the third aspect, it is preferable that the first structure and the second structure are each formed in a square shape when viewed from the detection direction.

  A force sensor according to a fifth aspect is the force sensor according to any one of the second to fourth aspects, wherein the first structure and the second structure each have a stopper that is abutted in the rotation direction as the suppression structure. It is preferable to provide.

  The force sensor according to a sixth aspect is the force sensor according to the fifth aspect, wherein the stopper includes a first protrusion protruding from an outer peripheral edge of one of the first structure and the second structure, and an outer peripheral edge of the other. A pair of second protrusions that protrude and sandwich the first protrusion is preferable.

  A force sensor according to a seventh aspect is the force sensor according to the fifth aspect, wherein the stopper is provided on a convex portion protruding from one outer peripheral edge of the first structure or the second structure and on the other outer peripheral edge. It is preferable that it is comprised with the recessed part which the said convex part fits.

  In the force sensor according to an eighth aspect, in the fifth aspect, the first structure and the second structure are provided with an insertion hole that continuously penetrates in the detection direction, and the stopper It is preferable to be configured by a hole and a pin inserted through the insertion hole.

  In any one of the second to eighth embodiments, the force sensor according to the ninth aspect projects from the outer peripheral edge of at least one of the first structure and the second structure toward the detection unit in the detection direction. It is preferable to further provide an edge.

  A force sensor according to a tenth aspect is the plate according to the ninth aspect, wherein one of the first structure and the second structure is a plate-like lid that closes an opening surrounded by the other edge. It is preferable.

  In the ninth or tenth aspect of the force sensor according to the eleventh aspect, it is preferable that the first structure and the second structure have the same structure.

  In a force sensor according to a twelfth aspect, in any one of the ninth to eleventh aspects, the edge includes a third structure that is separate from the first structure and the second structure. preferable.

  A force sensor according to a thirteenth aspect is the twelfth aspect, wherein the core has a hollow portion, covers an inner peripheral surface of the core, the first structure body, the second structure body, and the third structure. It is preferable to further include a fourth structure that is separate from the structure.

  According to a fourteenth aspect, in the thirteenth aspect, the first structure and the second structure each have a through-hole penetrating in the detection direction continuously with the hollow portion. A screw may be formed on at least one of the peripheral surface of the through hole of one structure, the peripheral surface of the through hole of the second structure, and the inner peripheral surface of the fourth structure. preferable.

  A force detection device according to a fifteenth aspect includes the force sensor according to any one of the first to fourteenth aspects, and a detection circuit that detects a load based on a change in magnetic characteristics of the coil.

  According to a sixteenth aspect, in the fifteenth aspect, the force detection device is mounted on a substrate housed in a space surrounded by the first structure, the second structure, and the elastic body. It is preferable.

  In a force detection device according to a seventeenth aspect, in the fifteenth aspect, it is preferable that the detection circuit is housed in a housing, and the housing is detachably attached to the force sensor.

  A force detection system according to an eighteenth aspect includes a plurality of force sensors according to any one of the first to fourteenth aspects, and the plurality of force sensors are respectively attached to a plurality of screws, and each of the plurality of screws is provided. It is characterized by detecting looseness.

  In a nineteenth aspect, the force detection system according to the nineteenth aspect preferably further includes a collection device that collects detection data from each of the plurality of force sensors.

  In a nineteenth aspect, a force detection system according to a twentieth aspect preferably further includes a receiving terminal that receives a data signal including the detection data collected by the collection device.

  A force detection method according to a twenty-first aspect uses a plurality of force sensors according to any one of the first to fourteenth aspects, attaches the plurality of force sensors to a plurality of screws, and loosens each of the plurality of screws. It is characterized by detecting.

  In the present invention, the first structure and the second structure are arranged on both sides in the predetermined detection direction of the core, and an elastic body is joined to both the first structure and the second structure. For this reason, in the present invention, since it is not necessary to provide the first structure and the second structure with a strain generating portion as in the conventional example, the dimension in the thickness direction of the first structure and the second structure is set. Can be small. Therefore, according to the present invention, the force sensor can be thinned by reducing the dimension in the thickness direction of the first structure and the second structure.

1A is a schematic diagram of a force sensor and a force detection device according to Embodiment 1. FIG. FIG. 1B is a plan view in which a part of the force sensor according to the first embodiment is omitted. FIG. 1C is a cross-sectional view of the force sensor according to the first embodiment. FIG. 3 is a schematic diagram of a detection circuit in the force detection device according to the first embodiment. 3 is a cross-sectional view of a configuration having a through hole in the force sensor according to Embodiment 1. FIG. FIG. 4A is a schematic diagram of an external appearance of the force detection device according to the first embodiment. FIG. 4B is a schematic diagram of an example of the force detection device according to the first embodiment. FIG. 5A is a cross-sectional view of the force sensor according to the second embodiment. FIG. 5B is a plan view in which a part of the force sensor according to the second embodiment is omitted. It is the schematic of the Example of the force detection apparatus which concerns on Embodiment 2. FIG. It is a disassembled perspective view of the force detection apparatus which concerns on Embodiment 3. FIG. FIG. 10 is a perspective view illustrating a cross section of a force detection device according to a third embodiment. 9A and 9B are diagrams illustrating examples of the first structure and the second structure of the force detection device according to the third embodiment, respectively. 10A and 10B are diagrams illustrating examples of the first structure and the second structure of the force detection device according to the third embodiment, respectively. FIG. 11A is a perspective view illustrating a cross section of a configuration in which a female screw is provided in the fourth structure in the force detection device according to the third embodiment. FIG. 11B is a perspective view illustrating a cross section of a configuration in which a female screw is provided in the first structure in the force detection device according to the third embodiment. FIG. 10 is an exploded perspective view illustrating an example of a force detection device according to a third embodiment. 10 is an exploded perspective view showing a first structure and a second structure in a force sensor according to Modification 1. FIG. It is a disassembled perspective view which shows the 1st structure in the force sensor which concerns on the modification 2, and a 2nd structure. It is a disassembled perspective view which shows the 1st structure in the force sensor which concerns on the modification 3, and a 2nd structure. It is a disassembled perspective view which shows the 1st structure in a force sensor which concerns on the modification 4, and a 2nd structure. 10 is an exploded perspective view showing a first structure and a second structure in a force sensor according to Modification 5. FIG. It is the schematic of the force detection system which concerns on embodiment. FIG. 19A and FIG. 19B are schematic views of examples of the force detection system according to the embodiment. 20A to 20C are schematic diagrams of wiring examples of the force detection system according to the embodiment.

  As shown in FIGS. 1A to 1C, the force sensor 2 according to the embodiment of the present invention includes a detection unit 20, a first structure 21 and a second structure 22, and an elastic body 23. The detection unit 20 includes a core 4 formed of a magnetic material and a coil 5 that is magnetically coupled to the core 4. In the detection unit 20, the magnetic flux generated by the coil 5 by energization passes through the core 4. The first structure 21 and the second structure 22 are respectively disposed on both sides of the core 4 in a predetermined detection direction. The elastic body 23 is provided between the outer peripheral edge of the first structure 21 and the outer peripheral edge of the second structure 22, joined to both, and is formed of a material having a lower elastic modulus than the core 4. And the detection part 20 is comprised so that the load applied from the 1st structure 21 and the 2nd structure 22 in the direction along a detection direction may be received.

  Moreover, the force detection apparatus 1 which concerns on embodiment of this invention is provided with the force sensor 2 and the detection circuit 3, as shown to FIG. 1A. The detection circuit 3 detects a load based on a change in the magnetic characteristics (inductance or conductance) of the coil 5.

  Moreover, the force detection system 100 according to the embodiment of the present invention includes a plurality of force sensors 2 as shown in FIG. The plurality of force sensors 2 are attached to the plurality of screws, respectively, and detect the looseness of each of the plurality of screws.

  The force detection method according to the embodiment of the present invention uses a plurality of force sensors 2 and attaches the plurality of force sensors 2 to a plurality of screws, respectively, and detects looseness of each of the plurality of screws.

  Hereinafter, the force sensor 2 and the force detection device 1 according to Embodiments 1 to 3 and Modifications 1 to 5 of the present invention will be described. However, the configuration described below is merely an example of the present invention, and the present invention is not limited to the following Embodiments 1 to 3 and Modifications 1 to 5. Further, the present invention can be modified in various ways according to the design and the like as long as it does not depart from the technical idea according to the present invention other than these embodiments and modifications.

  In the following description, the thickness direction (detection direction) of the core 4 is assumed to be the vertical direction, and the first structure 21 side is viewed downward and the second structure 22 side is viewed upward as viewed from the core 4. It is not intended to limit the usage of the sensor 2 and the force detection device 1.

<Embodiment 1>
The force detection device 1 according to the first embodiment of the present invention includes a force sensor 2 and a detection circuit 3 as shown in FIG. 1A. Moreover, the force sensor 2 of this embodiment is provided with the detection part 20, the 1st structure 21, the 2nd structure 22, the elastic body 23, and the board | substrate 24, as shown to FIG. 1A-FIG. 1C. ing. In addition, in FIG. 1B, illustration of the 2nd structure 22 and the elastic body 23 is abbreviate | omitted.

  As shown in FIG. 1A, the detection unit 20 includes a core 4 formed of a magnetic material and a coil 5 that is magnetically coupled to the core 4. The core 4 is made of a magnetic material such as Ni (nickel) -Zn (zinc) ferrite. The core 4 is formed in an annular shape in plan view and has a hollow portion 40. In addition, the core 4 should just be formed with the magnetic body which has a reverse magnetostriction effect, when a load is added to the core 4. FIG. The inverse magnetostriction effect is an effect in which the magnetized core 4 is distorted when a load is applied, and the permeability of the core 4 changes due to the distortion.

  The coil 5 is configured by winding a conducting wire around a part of the core 4 so as to alternately pass through the hollow portions 40 and the outside of the core 4. In addition, it is preferable to use the copper wire (for example, enamel wire etc.) coat | covered with the insulating material as a conducting wire. Here, the part (refer FIG. 1B) around which the conducting wire is wound in the core 4 is referred to as an “attachment part 41”.

  As shown in FIG. 1C, the mounting portion 41 is designed so that the coil 5 can be accommodated within the vertical dimension of other portions of the core 4. For this reason, in the force sensor 2 of the present embodiment, a part of the coil 5 does not protrude from the upper surface (or lower surface) of the core 4, so that no load is applied to the coil 5 even if a load is applied to the core 4. The disconnection of the coil 5 can be prevented. Note that whether or not the mounting portion 41 is designed with the above dimensions is arbitrary.

  As shown in FIG. 1B, magnetic flux generated when the coil 5 is energized passes through the core 4. For this reason, a magnetic path (magnetic circuit) M <b> 1 along the circumferential direction of the hollow portion 40 is formed in the core 4. This magnetic path M1 is a closed magnetic path. Therefore, in the force sensor 2 of the present embodiment, magnetic flux leakage from the core 4 to the outside is difficult to occur, so there is no need to provide a ferromagnetic case to prevent magnetic flux leakage.

  The first structure 21 and the second structure 22 are both plate-like members formed of, for example, a metal material. As shown in FIG. 1B, the first structure 21 is formed in a circular shape in plan view. In addition, the second structure 22 is formed in a circular shape in plan view, like the first structure 21. As shown in FIG. 1C, the first structure 21 is disposed on the lower side of the core 4 in contact with the lower surface of the core 4. Moreover, the 2nd structure 22 is arrange | positioned on the upper side of the core 4 in the form which contact | connects the upper surface of the core 4, as shown to FIG. 1C. That is, the first structure 21 and the second structure 22 are arranged so as to sandwich the core 4 from both sides in the vertical direction (detection direction). There may be gaps between the first structure 21 and the core 4 and between the second structure 22 and the core 4.

  In addition, the shape of the 1st structure 21 and the 2nd structure 22 is not limited to circular shape by planar view, For example, rectangular shape and annular | circular shape may be sufficient by planar view. Moreover, the 1st structure 21 and the 2nd structure 22 should just have the intensity | strength which can endure the assumed load. Furthermore, the first structure 21 and the second structure 22 may not be formed of a metal material, and may be formed of a resin material such as CFRP (Carbon-Fiber-Reinforced Plastic). Good.

  The elastic body 23 is an adhesive mainly composed of an epoxy resin or a silicone resin, for example. The elastic body 23 bonds the first structure 21 and the second structure 22 to each other by adhering to the outer periphery of the upper surface of the first structure 21 and the outer periphery of the lower surface of the second structure 22. The elastic body 23 is not limited to the adhesive, and may be formed of a material having a lower elastic modulus than the material forming the core 4.

  Moreover, the elastic body 23 should just be the structure provided between the outer periphery of the 1st structure 21, and the outer periphery of the 2nd structure 22, and joined to both. Further, in the force sensor 2 of the present embodiment, the elastic body 23 itself is an adhesive. However, for example, by providing the elastic body 23 with another adhesive such as a double-sided tape, the elastic body 23 becomes the first structure 21 and The structure joined to both of the 2nd structures 22 may be sufficient. Further, the elastic body 23 is not limited to the configuration provided over the entire outer periphery of the first structure 21 and the outer periphery of the second structure 22. That is, the elastic body 23 may be bonded to both the first structure 21 and the second structure 22 to such an extent that the inclination of the first structure 21 and the second structure 22 is suppressed.

  As shown in FIG. 1C, the substrate 24 is accommodated in a space surrounded by the first structure 21, the second structure 22, and the elastic body 23. The substrate 24 is fixed by the outer peripheral edge thereof being in contact with the elastic body 23. Further, the substrate 24 is formed in an annular shape in a plan view as shown in FIG. 16C, and its central portion has a circular positioning in a plan view having a diameter slightly larger than the diameter of the core 4. It is a hole 240. The core 4 is positioned at a predetermined position by fitting the core 4 into the positioning hole 240. In addition, the shape of the positioning hole 240 is not limited to a circular shape in a plan view, and may be a rectangular shape in a plan view, for example. That is, the positioning hole 240 may have a shape into which the core 4 is fitted.

  As shown in FIG. 2, the detection circuit 3 includes an oscillation circuit 30, a period measurement circuit 31, a square circuit 32, a temperature compensation circuit 33, and a signal processing circuit 34. The oscillation circuit 30 is configured to maintain the oscillation of the resonance circuit 35 including the coil 5. The oscillation circuit 30 is configured to output an oscillation signal that oscillates at a frequency corresponding to the resonance frequency of the resonance circuit 35. The period measurement circuit 31 is configured to measure the period of the oscillation signal output from the oscillation circuit 30 and output a signal corresponding to the measured period. The square circuit 32 is configured to calculate and output the square value of the signal output from the period measurement circuit 31. The temperature compensation circuit 33 is configured to suppress temperature fluctuation of the signal output from the squaring circuit 32 by temperature compensation processing. The signal processing circuit 34 is configured to detect a change in load applied to the core 4 based on a signal output from the temperature compensation circuit 33.

  As shown in FIG. 2, the equivalent circuit of the resonance circuit 35 includes a series circuit of an inductor 351 and a resistor 352 and a parallel circuit of a capacitor 353. Here, the inductance of the inductor 351 is equivalent to the inductance of the coil 5. Further, the resistance value of the resistor 352 is equivalent to the resistance value of the winding resistance of the coil 5. The capacitance value of the capacitor 353 is equivalent to the capacitance value of the parasitic capacitance of the coil 5. The resonance circuit 35 may be configured by electrically connecting a capacitor in parallel with the coil 5.

  In the force sensor 2 of the present embodiment, the detection circuit 3 is configured by mounting electronic components on the substrate 24. That is, in the force detection device 1 of the present embodiment, the detection circuit 3 is provided integrally with the force sensor 2. Note that the detection circuit 3 does not need to be provided on the substrate 24 and may be provided separately from the substrate 24. Further, the detection circuit 3 may be provided on a substrate outside the force sensor 2, for example. That is, in the force detection device 1 of the present embodiment, the detection circuit 3 may be provided separately from the force sensor 2.

  Hereinafter, operations of the force sensor 2 and the force detection device 1 of the present embodiment will be described. First, by supplying a current from an external power source to the coil 5, the core 4 is magnetized and the magnetic path M1 is formed. Here, the oscillation circuit 30 of the detection circuit 3 supplies a current to the coil 5.

  Next, when an upward load is applied to the lower surface of the first structure 21 (see the upward arrow shown in FIG. 1C), the first structure 21 is pushed up by bending the elastic body 23, and the first structure 21. A load is applied to the core 4 via. Then, due to the inverse magnetostrictive effect, the magnetic permeability of the core 4 changes according to the magnitude of the load, so that the inductance of the coil 5 changes. Similarly, when a load is applied downward (see the downward arrow shown in FIG. 1C) to the upper surface of the second structure 22, the second structure 22 is pushed down by the elastic body 23 being bent, and the second structure 22. A load is applied to the core 4 via. Also in this case, the inductance of the coil 5 changes according to the magnitude of the load. That is, in the force sensor 2 of the present embodiment, the core 4 (detection unit 20) is configured to receive a load applied from the first structure 21 and the second structure 22 in a direction along the vertical direction (detection direction). ing.

  When the inductance of the coil 5 changes, the resonance frequency of the resonance circuit 35 including the coil 5 changes. For this reason, the oscillation circuit 30 outputs an oscillation signal having a frequency corresponding to the resonance frequency of the resonance circuit 35, and the period measurement circuit 31 outputs a signal corresponding to the period of the oscillation signal. Here, the period of the oscillation signal is represented by the square root of the product of the inductance of the inductor 351 and the capacitance value of the capacitor 353 in the equivalent circuit. And since the square circuit 32 calculates and outputs the square value of the output signal of the period measurement circuit 31, the output signal of the square circuit 32 changes linearly with respect to the change of the inductance of the coil 5. The output signal of the square circuit 32 is corrected for temperature fluctuations by the temperature compensation circuit 33. The signal processing circuit 34 calculates the inductance of the coil 5 based on the output signal of the temperature compensation circuit 33, and calculates the load applied to the core 4 from the amount of change in the inductance of the coil 5. That is, the detection circuit 3 detects the load applied to the core 4 based on the change in the inductance of the coil 5.

  As described above, the force sensor 2 of the present embodiment has the first structure 21 and the second structure 22 arranged on both sides of the core 4 in the vertical direction (predetermined detection direction), and the first structure 21 and An elastic body 23 is joined to both of the second structures 22. For this reason, in the force sensor 2 of the present embodiment, the first structure 21 and the second structure 22 need not be processed to provide strain-generating portions as in the conventional example. The dimension of the body 22 in the thickness direction can be reduced. Therefore, the force sensor 2 of the present embodiment can be thinned by reducing the thickness direction dimensions of the first structure 21 and the second structure 22. Further, the force sensor 2 of the present embodiment includes an elastic body 23. For this reason, the force sensor 2 of the present embodiment can improve the load detection accuracy because the load is easily transmitted to the core 4 when a load is applied to the first structure 21 or the second structure 22. .

  In particular, in the force sensor 2 of the present embodiment, the elastic body 23 has a structure that is provided between the outer peripheral edge of the first structure 21 and the outer peripheral edge of the second structure 22 and is joined to both. Yes. For this reason, when a load is applied to the first structure 21 or the second structure 22, the force sensor 2 of the present embodiment has the core 4 from the first structure 21 and the second structure 22 in the direction along the detection direction. Easy to receive applied load. Therefore, the force sensor 2 according to the present embodiment is structurally stable and difficult to swing, and the load of the core 4 is easily transmitted properly (in other words, it is difficult to apply a load locally), so that the load detection accuracy is improved. be able to.

  Further, when the thickness of the core 4 is reduced, it is a design problem to make it difficult for magnetic saturation to occur. However, the force sensor 2 according to the present embodiment can easily transmit force properly to the core 4. Therefore, there is an advantage that it is easy to make the core 4 thinner.

  Further, in the force sensor 2 of the present embodiment, the coil 5 is provided so that the magnetic path M1 formed when the coil 5 is energized is a closed magnetic path, but the coil 5 has a conducting wire along the outer periphery of the core 4. You may be comprised by winding. In this configuration, the magnetic flux generated when the coil 5 is energized forms a magnetic path that passes not only inside the core 4 but also outside the core 4. That is, in this configuration, the magnetic path is an open magnetic path. This configuration has an advantage that the core 4 is easy to manufacture because it is not necessary to process the core 4 by providing the attachment portion 41 or the like. In addition, this configuration has an advantage that the coil 5 can be easily manufactured because the coil 5 can be manufactured simply by winding a conducting wire around the outer periphery of the core 4. That is, in this configuration, the core 4 and the coil 5 can be easily designed, so that the force sensor 2 can be easily reduced in size and thickness. When the coil 5 is configured by winding a conducting wire along the outer periphery of the core 4, the core 4 may not have the hollow portion 40.

  Here, in the force sensor 2 of the present embodiment, as shown in FIG. 3, the first structure 21 and the second structure 22 are respectively continuous with the hollow portion 40 of the core 4 in the vertical direction (detection direction). You may have the circular through-holes 210 and 220 by planar view which penetrates. The through holes 210 and 220 are used, for example, to pass the shaft portion of the bolt through the hollow portion 40 of the core 4. In addition, the shape of the through holes 210 and 220 is not limited to a circular shape in a plan view, and may be a shape that allows a shaft portion of a bolt to pass therethrough, for example. In this configuration, the elastic body 23 is also provided between the periphery of the through hole 210 in the first structure 21 and the periphery of the through hole 220 in the second structure 22.

  In addition, in the force sensor 2 of this embodiment, it is arbitrary whether the board | substrate 24 is provided. That is, the force sensor 2 of the present embodiment does not need to be provided with the substrate 24 as long as the core 4 is positioned by the first structure 21, the second structure 22, and the elastic body 23. However, if it is the structure provided with the board | substrate 24, it is not necessary to provide the structure for processing the 1st structure 21 and the 2nd structure 22, and positioning the core 4, and the 1st structure 21 and the 2nd structure There is an advantage that the thickness dimension of 22 can be reduced.

  Further, in the force detection device 1 of the present embodiment, the detection circuit 3 does not include the squaring circuit 32 and the temperature compensation circuit 33, and the signal processing circuit 34 changes the load based on the signal output from the period measurement circuit 31. The structure which detects this may be sufficient. In addition, the configuration of the detection circuit 3 illustrated in FIG. 2 is an example, and the detection circuit 3 may be any other configuration as long as it detects a load based on a change in magnetic characteristics (inductance or conductance) of the coil 5. May be.

  Hereinafter, an example in which the tightening axial force is detected using the force detection device 1 of the present embodiment will be described with reference to FIGS. 4A and 4B. The tightening axial force refers to a load along the axial direction of the bolt B1 applied to the structure A1 (for example, a wall or a ceiling) when the nut C1 is tightened against the bolt B1 (see FIG. 4B). .

  In this example, as shown in FIG. 4A, the force detection device 1 of the present embodiment is configured by housing a force sensor 2 and a substrate 300 on which the detection circuit 3 is mounted in a case 10. The case 10 includes a semi-disc-shaped first case 10A that protects the force sensor 2 and a flat rectangular parallelepiped second case 10B that protects the substrate 300. Here, the case 10 includes the first structure 21, the second structure 22, and the elastic body 23 of the force sensor 2.

  Hereinafter, the usage method of the force detection apparatus 1 of this embodiment is demonstrated. First, the bolt B1 is passed from the back side (the lower side in FIG. 4B) of the structure A1. In FIG. 4B, the head of the bolt B1 is not shown. Next, the shaft part B10 protruding to the front side of the structure A1 (upper side in FIG. 4B) is passed through the through holes 210 and 220 and the hollow part 40 of the core 4. And the nut C1 is fastened with respect to the axial part B10 in the form which pinches | interposes 1st case 10A between structures A1. Then, a tightening axial force is applied to the detection unit 20 via the first structure 21 and the second structure 22. Therefore, the force detection device 1 of the present embodiment can detect the tightening axial force by detecting the load applied by the detection circuit 3 to the detection unit 20.

<Embodiment 2>
The force sensor 2 and the force detection device 1 according to the second embodiment of the present invention are used, for example, in a ground anchor method. Here, the ground anchor method will be briefly described. For example, when a slope is formed by excavation or embankment of a natural ground, a ground anchor method is generally used to stabilize a structure provided on the slope. In order to detect and monitor the tensile force of the anchor used in this ground anchor method, it is conceivable to use the force sensor 2 and the force detection device 1 of the first embodiment.

  Here, when using the force sensor 2 of Embodiment 1 for a large member like an anchor, it is necessary to use the core 4 with a large diameter according to a large member. However, it is difficult to increase the diameter of the core 4 without increasing the dimension of the core 4 in the thickness direction. In the force sensor 2 of the first embodiment, the core 4 can be prevented from being enlarged in the thickness direction. Absent. Therefore, when detecting the load of a large member, the force sensor 2 preferably includes a plurality of detection units 20.

  Hereinafter, the force sensor 2 and the force detection device 1 of the present embodiment including a plurality of detection units 20 will be described with reference to the drawings. In the force sensor 2 and the force detection device 1 of the present embodiment, the description of the components common to the first embodiment will be omitted as appropriate.

  As shown in FIGS. 5A and 5B, the force sensor 2 of the present embodiment includes a plurality of (here, twelve) detection units 20, a first structure 21, a second structure 22, and an elastic body 23. And a substrate 24. The some detection part 20 is arrange | positioned along the plane orthogonal to an up-down direction (detection direction). In FIG. 5B, the second structure 22 and the elastic body 23 are not shown. Further, “orthogonal” is an expression including “substantially orthogonal” as well as complete “orthogonal”.

  The first structure 21 is formed in a square shape in plan view as shown in FIG. 5B. In addition, the second structure 22 is formed in a square shape in a plan view like the first structure 21. As shown in FIG. 5A, the first structure 21 is disposed below the plurality of cores 4 in contact with the lower surfaces of the plurality (two in the drawing) of the cores 4. Further, as shown in FIG. 5A, the second structure 22 is disposed on the upper side of the plurality of cores 4 so as to be in contact with the upper surfaces of the plurality (two in the drawing) of the cores 4. That is, the first structure 21 and the second structure 22 are arranged so as to sandwich the plurality of cores 4 from both sides in the vertical direction (detection direction).

  As shown in FIG. 5A and FIG. 5B, the first structure 21 is provided with a circular through hole 210 in a plan view that penetrates the central portion in the vertical direction (detection direction). Further, as shown in FIG. 5A, the second structure 22 is provided with a circular through hole 220 in a plan view penetrating through the center portion in the vertical direction (detection direction). In addition, the shape of the through holes 210 and 220 is not limited to a circular shape in plan view, and may be a shape that allows a shaft portion of a bolt or a tendon D111 (described later) to pass therethrough.

  As shown in FIG. 5A, the elastic body 23 is bonded to the outer peripheral edge of the upper surface of the first structure 21 and the outer peripheral edge of the lower surface of the second structure 22, so that the first structure 21 and the second structure The bodies 22 are joined together. Further, as shown in FIG. 5A, the elastic body 23 is bonded to the periphery of the through hole 210 on the upper surface of the first structure 21 and the periphery of the through hole 220 on the lower surface of the second structure 22. The first structure 21 and the second structure 22 are coupled to each other. That is, the elastic body 23 may be configured to be joined to both the first structure 21 and the second structure 22.

  As shown in FIG. 5A, the substrate 24 is accommodated in a space surrounded by the first structure 21, the second structure 22, and the elastic body 23. The board | substrate 24 is formed in square shape by planar view, as shown to FIG. 5B. Further, a circular through hole 241 is provided in the center of the substrate 24 in a plan view having a diameter (for example, a diameter of 140 mm) slightly larger than the diameter of the through holes 210 and 220. Similar to the through holes 210 and 220, the through hole 241 may have a shape that allows the shaft portion of the bolt and the tendon D111 to pass therethrough. The substrate 24 is fixed such that the outer peripheral edge thereof and the peripheral surface of the through hole 241 are in contact with the elastic body 23.

  Further, as shown in FIG. 5B, the substrate 24 is provided with a plurality (12 in the drawing) positioning holes 240 around the through hole 241. Each positioning hole 240 is formed in a circular shape in plan view, and is provided at equal intervals along the circumferential direction of the through hole 241. The shape of the positioning hole 240 is not limited to a circular shape in plan view, and may be any shape as long as the core 4 is fitted.

  Hereinafter, the Example which detects the tensile force of the anchor D1 used by the ground anchor construction method using the force sensor 2 and the force detection apparatus 1 of this embodiment is described with reference to FIG. In FIG. 6, illustration of the detection circuit 3 is omitted. The anchor D1 is used to transmit the tensile force from the structure A1 to the ground. The anchor D1 includes an anchor body having a function of transmitting a tensile force to the ground, an anchor head D10 for coupling the anchor D1 to the structure A1, and a tension portion that transmits the tensile force from the anchor head D10 to the anchor body. And D11.

  The anchor head D10 includes a nut D101 that is a fixing tool and an anchor structure D102 that is a bearing plate arranged on the structure A1. The anchor structure D102 is provided with a hole D103 through which the tendon D111 can pass. The tension portion D11 includes a bar-shaped tendon D111 made of, for example, a PC (Prestressed Concrete) steel strand. An anchor body is mechanically connected to the first end of the tendon D111 in the longitudinal direction. Further, the second end of the tendon D111 in the longitudinal direction is passed through the hole D103 of the anchor structure D102 and the through holes 210, 220, and 241 of the force sensor 2 of the present embodiment, and the nut D101 is tightened. Yes.

  The force sensor 2 of the present embodiment is arranged in a form sandwiched between the nut D101 and the anchor structure D102. Therefore, the force detection device 1 of the present embodiment can detect the tensile force of the anchor D1 when the detection circuit 3 detects a load in which the nut D101 pushes down one surface of the force sensor 2.

  As described above, the force sensor 2 and the force detection device 1 of the present embodiment are configured to detect a load using a plurality of detection units 20 instead of a single detection unit 20. Therefore, the force sensor 2 and the force detection device 1 according to the present embodiment can reduce the diameter of the core 4 of each detection unit 20 as compared with the case where only one detection unit 20 is provided. The dimension in the thickness direction of 4 can also be reduced. Therefore, the force sensor 2 and the force detection device 1 of the present embodiment can be thinned even when used for a large member such as the anchor D1.

<Embodiment 3>
Hereinafter, a force sensor 2 and a force detection device 1 according to Embodiment 3 of the present invention will be described with reference to the drawings. In the force sensor 2 and the force detection device 1 of the present embodiment, the description of the components common to the first embodiment will be omitted as appropriate. As shown in FIGS. 7 and 8, the force detection device 1 of the present embodiment includes a force sensor 2 and a substrate 36. The force sensor 2 includes a first structure 21, a second structure 22, an elastic body 23, a third structure 25, a fourth structure 26, a core 4, and a coil 5. In addition, illustration of the elastic body 23 is abbreviate | omitted in FIG.

  The first structure 21 is a flat plate and is formed in a quadrangular shape in plan view. The first structure 21 is integrally formed with a flat step portion 211 that protrudes upward from the upper surface thereof. Similarly, the second structure 22 is a flat plate and is formed in a square shape in plan view. The second structure 22 is integrally formed with a flat step portion 221 that protrudes downward from the lower surface thereof. Each of the first structure 21 and the second structure 22 has circular through holes 210 and 220 that are continuous with the hollow portion 40 of the core 4 and penetrate in the vertical direction (detection direction) in plan view. Yes. That is, in the force detection device 1 of the present embodiment, the first structure 21 and the second structure 22 have the same structure.

  The third structure 25 is formed in a rectangular tube shape. The opening on the lower side of the third structure 25 is closed by the first structure 21 when the step portion 211 of the first structure 21 is fitted. Further, the third structure 25 is provided with a circular hole 250 in plan view. The hole 250 is used for passing a connector for electrical connection with a detection circuit 3 provided on the substrate 36 described later. The upper opening of the third structure 25 is closed by the second structure 22 when the step 221 of the second structure 22 is fitted.

  The outer peripheral edge of the upper surface of the first structure 21 and the outer peripheral edge of the lower surface of the third structure 25 are joined by the elastic body 23. Further, the outer peripheral edge of the lower surface of the second structure 22 and the outer peripheral edge of the upper surface of the third structure 25 are joined by the elastic body 23. The substrate 36 and the core 4 having the coil 5 are accommodated in a space surrounded by the first structure 21, the second structure 22, the third structure 25, and the elastic body 23.

  The fourth structure 26 has a cylindrical shape and is dimensioned to fit in the hollow portion 40 of the core 4. The hollow portion of the fourth structure 26 is used together with the through holes 210 and 220 to pass, for example, a bolt shaft portion. The peripheral edge of the through hole 210 on the upper surface of the first structure 21 and the lower surface of the fourth structure 26 are joined by the elastic body 23. Further, the peripheral edge of the through hole 220 on the lower surface of the second structure 22 and the upper surface of the fourth structure 26 are joined by the elastic body 23.

  The substrate 36 has a rectangular shape in plan view, and is formed with a size that fits inside the third structure 25. A circular positioning hole 360 is provided in the center of the substrate 36 in a plan view having a diameter slightly larger than the outer diameter of the core 4. The core 4 is positioned at a predetermined position by fitting the core 4 into the positioning hole 360. Electronic parts constituting the detection circuit 3 are mounted on the substrate 36 except for the positioning holes 360. That is, the detection circuit 3 is mounted on the substrate 36.

  Here, as a comparative example of the force sensor 2 of the present embodiment, a configuration in which the first structure 21 and the second structure 22 are formed in a circular shape in plan view is considered. In this configuration, for example, a case where a bolt is inserted inside the through holes 210 and 220 and the fourth structure 26 and a nut is tightened with respect to the bolt is considered. In this case, when tightening the nut, a clockwise (or counterclockwise) moment is applied to the first structure 21 (second structure 22). Then, around the axis X1 (see FIG. 7) along the vertical direction (detection direction), the first structure 21 (second structure 22) is relative to the second structure 22 (first structure 21). There is a possibility to rotate. When the first structure 21 (second structure 22) rotates relative to the second structure 22 (first structure 21) in this way, the first structure 21 (second structure 22) is transformed. A moment is applied to the elastic body 23 in contact therewith. Then, a part of the elastic body 23 may be broken or peeled off, and the joining by the elastic body 23 may be incomplete. And if the joining by the elastic body 23 becomes incomplete, the load detection accuracy by the force sensor 2 may be lowered.

  Therefore, the force sensor 2 of the present embodiment further includes a suppression structure S1 that suppresses relative rotation of the first structure 21 and the second structure 22 around the axis along the vertical direction (detection direction). Specifically, in the force sensor 2 of the present embodiment, the first structure 21 and the second structure 22 are each formed in a quadrangular shape when viewed from the vertical direction (detection direction). That is, in the force sensor 2 of the present embodiment, the first structure 21 and the second structure 22 are each formed in a non-circular shape as viewed from the vertical direction (detection direction) as the suppression structure S1.

  Further, in the force sensor 2 of the present embodiment, the third structure 25 as well as the first structure 21 and the second structure 22 are formed in a quadrangular shape when viewed from the vertical direction (detection direction). The first structure 21 and the second structure 22 are fitted in the openings of the third structure 25, respectively.

  That is, in the force sensor 2 of the present embodiment, the first structure 21 and the second structure 22 do not have perfect rotational symmetry like a perfect circle, but have asymmetry in which rotational symmetry is broken. ing. For this reason, even when a clockwise (or counterclockwise) moment is applied to the first structure 21 (second structure 22) when the nut is tightened, the first structure 21 (first structure) is added to the third structure 25. 2 structure 22) is caught, the rotation of the first structure 21 (second structure 22) is hindered. For this reason, in the force sensor 2 of the present embodiment, since it is difficult for a moment to be applied to the elastic body 23, the joining by the elastic body 23 is unlikely to be incomplete, and as a result, the load detection accuracy is unlikely to decrease.

  In the force sensor 2 of the present embodiment, the first structure 21 and the second structure 22 have a quadrangular shape in plan view, but may be non-circular in plan view, for example, in a triangular shape in plan view, It may be a polygonal shape with many corners. Further, the first structure 21 and the second structure 22 may be oval or trapezoidal in plan view. In addition, the first structure 21 and the second structure 22 may have a shape with a corner in a part of a circle in plan view.

  Incidentally, in the force sensor 2 of the present embodiment, for example, as shown in FIG. 9A, an edge 22 </ b> A may be provided in the second structure 22 instead of including the third structure 25. Both the first structure 21 and the second structure 22 are formed in a non-circular shape combining a circle and a quadrangle in plan view. The edge 22A is formed integrally with the second structure 22 so as to protrude downward from the outer peripheral edge of the second structure 22. The elastic body 23 is bonded to both the outer peripheral edge of the upper surface of the first structure 21 and the lower surface of the edge portion 22A.

  In addition to the configuration shown in FIG. 9A, as shown in FIG. 9B, the step portion 211 of the first structure 21 may be provided with a recessed portion 211A that is recessed downward. 9A and 9B, the components other than the first structure 21 and the second structure 22 are not shown.

  9A and 9B, even when the core 4 or the substrate 36 moves along the radial direction (the radial direction of the core 4) by applying an external force, the core 4 or the substrate 36 contacts the edge 22A. The movement is restricted. That is, in the configuration shown in FIGS. 9A and 9B, the movement of the core 4 in the radial direction can be restricted, and the core 4 can be prevented from jumping out along the radial direction.

  In the configuration shown in FIGS. 9A and 9B, the first structure 21 is a lid that closes the opening surrounded by the edge 22A. For this reason, in the configuration shown in FIGS. 9A and 9B, since the edge 22A and the first structure 21 face each other in the radial direction, even if an external force is applied along the radial direction, the first structure 21 and The wobbling in the radial direction of the second structure 22 and the core 4 can be suppressed. As a result, in the configuration shown in FIGS. 9A and 9B, the detection accuracy with respect to the load can be improved.

  In addition, in the force sensor 2 of the present embodiment, for example, as shown in FIGS. 10A and 10B, an edge 21 </ b> A may be provided in the first structure 21 instead of including the third structure 25. Both the first structure 21 and the second structure 22 are formed in a non-circular shape combining a circle and a quadrangle in plan view. The edge 21A is formed integrally with the first structure 21 so as to protrude upward from the outer peripheral edge of the first structure 21. Moreover, the 1st structure 21 has a pair of prismatic base 21B instead of the step part 211. FIG. The pair of pedestals 21 </ b> B are integrally formed with the first structure 21 so as to protrude upward from the upper surface of the first structure 21.

  The 2nd structure 22 does not have the step part 221, but is formed in the dimension fitted in the opening enclosed by the edge part 21A. The second structure 22 is supported by the pair of bases 21 </ b> B and the core 4. The elastic body 23 is joined to both the first structure 21 and the edge 22A. In FIG. 10A, illustration of the constituent elements excluding the first structure 21 and the second structure 22 is omitted. Further, in FIG. 10B, illustration of components other than the first structure 21 and the second structure 22 and the core 4 is omitted.

  In this configuration, similarly to the configurations shown in FIGS. 9A and 9B, the movement of the core 4 in the radial direction can be restricted, and the core 4 can be prevented from jumping out along the radial direction. In this configuration, the second structure 22 is a lid that closes the opening surrounded by the edge portion 21A. For this reason, in this configuration, as in the configurations shown in FIGS. 9A and 9B, even if an external force is applied along the radial direction, the first structural body 21 and the second structural body 22 and the radial direction of the core 4 The wobble can be suppressed, and the detection accuracy with respect to the load can be improved.

  That is, in the force sensor 2 of the present embodiment, the edges 21A and 22A that protrude from the outer peripheral edge of at least one of the first structure 21 and the second structure 22 to the detection unit 20 side in the vertical direction (detection direction) are further provided. You may have. In the force sensor 2 of the present embodiment, either one of the first structure 21 and the second structure 22 may be a lid that closes an opening surrounded by the other edges 21A and 22A.

  Here, the force sensor 2 of the present embodiment, as shown in FIGS. 7 and 8, instead of integrally forming the edge 21 </ b> A (edge 22 </ b> A) with the first structure 21 (second structure 22). The third structure 25 is provided. That is, in the force sensor 2 of the present embodiment, the edge portion 21 </ b> A (edge portion 22 </ b> A) includes the third structure 25 that is separate from the first structure 21 and the second structure 22.

  Thus, in the force sensor 2 of this embodiment, each structure 21, 22, 23 is divided and formed. For this reason, in the force sensor 2 of this embodiment, each structure 21 and 22 is compared with the case where several structures are integrally formed, for example, the edge part 21A is integrally formed with the 1st structure 21. , 23 can be easily formed by pressing or the like, and the cost can be reduced. In particular, the force sensor 2 of the present embodiment can reduce the cost more effectively when the structures 21, 22, and 23 are formed of a metal material. Whether or not the third structure 25 is provided is arbitrary.

  Moreover, in the force sensor 2 of this embodiment, the 1st structure 21 and the 2nd structure 22 are the same structures. For this reason, in force sensor 2 of this embodiment, since common parts can be used as the 1st structure 21 and the 2nd structure 22, cost can be reduced further. Note that whether or not to adopt the configuration is arbitrary.

  Further, in the force sensor 2 of the present embodiment, the core 4 has a hollow portion 40 as shown in FIGS. The force sensor 2 further includes a fourth structure 26 that covers the inner peripheral surface of the core 4 and is separate from the first structure 21, the second structure 22, and the third structure 25. For this reason, in the force sensor 2 of this embodiment, compared with the case where several structure bodies, such as forming the 4th structure body 26 integrally with the 2nd structure body 22, for example, are formed integrally, a 4th structure body. 26 can be easily formed by pressing or the like, and the cost can be reduced. It is optional whether or not the fourth structure 26 is provided.

  Moreover, in the force sensor 2 of this embodiment, as shown to FIG. 11A, the internal thread (screw) 220A may be formed in the surrounding surface of the through-hole 220 of the 2nd structure 22. As shown in FIG. In this configuration, since the force sensor 2 can be tightened with respect to the bolt, the force sensor 2 can be used instead of the nut. Of course, the internal thread (screw) may be formed not on the peripheral surface of the through hole 220 of the second structure 22 but on the peripheral surface of the through hole 210 of the first structure 21.

  Further, in the force sensor 2 of the present embodiment, as shown in FIG. 11B, a female screw (screw) 26 </ b> A may be formed on the inner peripheral surface of the fourth structure 26. Even in this configuration, the force sensor 2 can be used instead of the nut.

  That is, in the force sensor 2 of the present embodiment, the first structure body 21 and the second structure body 22 have through-holes 210 and 220 that pass through the hollow portion 40 in the vertical direction (detection direction), respectively. May be. A screw is formed on at least one of the peripheral surface of the through hole 210 of the first structure 21, the peripheral surface of the through hole 220 of the second structure 22, and the inner peripheral surface of the fourth structure 26. May be.

  By the way, in the force detection apparatus 1 of this embodiment, as already stated, the board | substrate 36 with which the detection circuit 3 was mounted is the 1st structure 21, the 2nd structure 22, the 3rd structure 25, and an elastic body. 23 is housed in a space surrounded by 23. That is, the detection circuit 3 is mounted on the substrate 36 housed in a space surrounded by the first structure 21, the second structure 22, and the elastic body 23. For this reason, in the force detection apparatus 1 of this embodiment, since the housing | casing for accommodating the detection circuit 3 is unnecessary, cost can be reduced.

  Whether or not to adopt the above configuration is arbitrary. That is, the force detection device 1 may include a housing for housing the detection circuit 3. For example, as shown in FIG. 12, the force detection device 1 may include a force sensor 2 and a housing 37. The housing 37 accommodates a substrate 36 on which the detection circuit 3 is mounted.

  The housing 37 includes a male connector 37 </ b> A that is electrically connected to the detection circuit 3. The force sensor 2 includes a female connector 2A that has an opening into which the male connector 37A is fitted and is electrically connected to the male connector 37A. For this reason, the housing | casing 37 is attached with respect to the force sensor 2 so that attachment or detachment is possible.

  That is, the detection circuit 3 may be stored in the housing 37. And the housing | casing 37 may be attached to the force sensor 2 so that attachment or detachment is possible. In this configuration, since the force sensor 2 and the housing 37 can be manufactured separately, the yield can be improved. Further, in this configuration, for example, even when the first structure 21 and the second structure 22 of the force sensor 2 are formed of a metal material, the casing 37 can be formed of a resin material, thereby reducing costs. can do.

  Note that the force detection device 1 may be configured by folding the flexible substrate so as to sandwich the core 4 without including the housing 37, for example. In this case, the detection circuit 3 is mounted on a flexible substrate.

  Each structure 21, 22, 25, 26 may be formed of a resin material such as CFRP, for example. In this configuration, the structures 21, 22, 25, and 26 are easier to mold than the case where the structures 21, 22, 25, and 26 are formed of a metal material, and the cost can be reduced.

  Hereinafter, the force sensors 2 according to the first to fifth modifications of the third embodiment will be described with reference to FIGS. In addition, in the force sensor 2 of each modification, description is abbreviate | omitted suitably about the component which is common in Embodiment 3. FIG. Further, the force sensor 2 of each modified example does not include the third structure 25. In addition, in FIGS. 13 to 17, the components other than the first structure 21 and the second structure 22 are not shown.

  In the force sensors 2 of the first to fifth modifications, as shown in FIGS. 13 to 17, as the suppression structure S <b> 1, the first structure body 21 and the second structure body 22 are stoppers S <b> 11 to butt in the direction of rotation, respectively. S15 is provided. Here, “rotation” refers to relative rotation of the first structure 21 and the second structure 22 around the axis X1 along the vertical direction (detection direction). For this reason, in the force sensors 2 of the first to fifth modifications, as in the third embodiment, since it is difficult to apply a moment to the elastic body 23, the joining by the elastic body 23 is unlikely to be incomplete, and as a result, the load detection accuracy is high. It is hard to decline.

<Modification 1>
In the force sensor 2 of Modification 1, as shown in FIG. 13, the first structure 21 and the second structure 22 are each formed in a circular shape in plan view. Further, the edge portion 21 </ b> A is formed integrally with the first structure 21. The edge portion 21A has a plurality (three in the drawing) of claws 212 protruding upward from the upper edge. The plurality of claws 212 are provided at equal intervals along the circumferential direction of the edge portion 21A. In addition, on the upper surface of the second structure 22, a plurality of recesses 222 (three in the drawing) in which the tips of the claws 212 are hooked are provided. The plurality of depressions 222 are provided at equal intervals along the circumferential direction of the second structure 22.

  In the force sensor 2 of the present modified example, the claws 212 are respectively caught in the plurality of depressions 222, whereby the relative rotation of the first structure 21 and the second structure 22 is suppressed. That is, in the force sensor 2 of this modification, the stopper S11 is configured by the claw 212 and the recess 222. In the force sensor 2 of this modification, the claw 212 and the recess 222 function as the stopper S11 if provided one by one.

<Modification 2>
In the force sensor 2 of Modification 2, as shown in FIG. 14, the first structure 21 and the second structure 22 are each formed in a circular shape in plan view. Further, the edge portion 21 </ b> A is formed integrally with the first structure 21. The edge 21 </ b> A is integrally formed with a rectangular protrusion 21 </ b> C in a plan view that protrudes in the radial direction. Further, a pair of quadrangular prism-shaped second protrusions 213 are integrally formed on the edge portion 21A so as to sandwich the protruding portion 21C. The pair of second protrusions 213 protrudes in the vertical direction (detection direction). The second structure 22 is integrally provided with a first protrusion 223 that is rectangular in a plan view that protrudes in the radial direction.

  In the force sensor 2 of the present modification, the first structure 21 and the second structure 22 are formed by sandwiching the first protrusion 223 protruding in the radial direction between the pair of second protrusions 213 protruding in the detection direction. The relative rotation of is suppressed. That is, in the force sensor 2 of the present modification, the stopper S12 includes the first protrusion 223 and the pair of second protrusions 213. The first protrusion 223 protrudes from the outer peripheral edge of one of the first structure 21 and the second structure 22 (here, the second structure 22). The pair of second protrusions 213 protrudes from the outer peripheral edge of the other (here, the first structure 21) and sandwiches the first protrusion 223.

<Modification 3>
In the force sensor 2 of Modification 3, as shown in FIG. 15, the first structure 21 and the second structure 22 are each formed in a circular shape in plan view. Further, the edge portion 21 </ b> A is formed integrally with the first structure 21. The second structure 22 is integrally formed with a pair of flat first protrusions 224 that protrude downward from the outer peripheral edge. The pair of first protrusions 224 are provided at equal intervals along the circumferential direction of the second structure 22. Two pairs of quadrangular prism-shaped second protrusions 214 protruding in the radial direction are integrally formed on the edge portion 21A. The two pairs of second protrusions 214 are provided at equal intervals along the circumferential direction of the edge portion 21A.

  In the force sensor 2 of the present modification, the first structure 21 and the second structure are formed by sandwiching the first protrusion 224 protruding in the detection direction between the pair of second protrusions 214 protruding in the radial direction. The relative rotation of 22 is suppressed. That is, in the force sensor 2 of the present modification, the stopper S13 includes the first protrusion 224 and the pair of second protrusions 214. The first protrusion 224 protrudes from the outer peripheral edge of one of the first structure 21 and the second structure 22 (here, the second structure 22). The pair of second protrusions 214 protrude from the outer peripheral edge of the other (here, the first structure 21) and sandwich the first protrusion 224.

<Modification 4>
In the force sensor 2 of the modification 4, as shown in FIG. 16, the 1st structure 21 and the 2nd structure 22 are each formed in circular shape by planar view. The first structure 21 is integrally formed with a plurality (three in the drawing) of convex portions 215 protruding upward from the outer peripheral edge. Further, the first structure 21 has a plurality of (three in the drawing) recesses 216 provided between the plurality of projections 215.

  The second structure 22 is integrally formed with a plurality (three in the drawing) of convex portions 225 protruding downward from the outer peripheral edge. The second structure 22 has a plurality (three in the drawing) of recesses 226 provided between the plurality of protrusions 225.

  In the force sensor 2 of the present modified example, the convex portions 215 and 225 are fitted into the concave portions 226 and 216, so that the relative rotation of the first structure 21 and the second structure 22 is suppressed. That is, in the force sensor 2 of the present modification, the stopper S14 includes the convex portions 215 and 225 and the concave portions 216 and 226. The convex portions 215 and 225 protrude from the outer peripheral edge of one of the first structure 21 and the second structure 22. The concave portions 216 and 226 are provided on the other outer peripheral edge, and the convex portions 225 and 215 are fitted therein.

<Modification 5>
In the force sensor 2 of Modification 5, as shown in FIG. 17, the first structure 21 and the second structure 22 are each formed in a shape combining a semicircle and a quadrangle in plan view. Further, the edge portion 21 </ b> A is formed integrally with the first structure 21. The first structure 21 is provided with a pair of circular insertion holes 217 penetrating in the vertical direction (detection direction) in plan view. Further, the second structure 22 is provided with a pair of circular insertion holes 227 penetrating in the vertical direction (detection direction) in plan view. The insertion holes 217 and 227 are provided at positions that are continuous with each other in the vertical direction (detection direction).

  Further, the force sensor 2 of the present modification includes a pair of cylindrical pins 27. The pin 27 is formed with a dimension that is inserted through the insertion holes 217 and 227.

  In the force sensor 2 of the present modification, the pins 27 are inserted into the pair of insertion holes 217 and 227, respectively, and the upper and lower ends of the pins 27 are caulked, whereby the first structure 21 and the second structure 22 are relatively moved. Rotation is suppressed. That is, in the force sensor 2 of the present modification, the first structure 21 and the second structure 22 are provided with insertion holes 217 and 227 that continuously penetrate in the vertical direction (detection direction). The stopper S15 includes insertion holes 217 and 227 and pins 27 that are inserted through the insertion holes 217 and 227.

  When the force sensor 2 includes any of the above-described stoppers S11 to S15, the first structure 21 and the second structure 22 are each formed in a non-circular shape when viewed from the vertical direction (detection direction). It does not have to be.

  By the way, when the bolt is inserted into the force sensor 2 and the nut is tightened with respect to the bolt, for example, a shim ring (bearing) may be inserted through the bolt so as to be positioned between the nut and the force sensor 2. In this configuration, when the nut is tightened, a clockwise (or counterclockwise) moment is applied to the shim ring (bearing), and a clockwise (or counterclockwise) moment is hardly applied to the force sensor 2. That is, the shim ring (bearing) functions as the suppression structure S1. In this configuration, the above-described stoppers S11 to S15 are unnecessary.

<Force detection system and force detection method>
Hereinafter, a force detection system 100 and a force detection method according to an embodiment of the present invention will be described. However, the configuration described below is merely an example of the present invention, and the present invention is not limited to the following embodiment. Further, the present invention can be modified in various ways according to the design and the like as long as it does not depart from the technical idea of the present invention, even if it is other than this embodiment.

  As shown in FIG. 18, the force detection system 100 of this embodiment includes a plurality of force sensors 2, a collection device 6, and a reception terminal 7. The plurality of force sensors 2 are the force sensors 2 according to any of the first to third embodiments and the first to fifth modifications, respectively.

  The plurality of force sensors 2 and the collection device 6 are electrically connected to each other through a power line 101 and a signal line 102, respectively. Here, the power supply line 101 is composed of two lines including a ground line. That is, in the force detection system 100 of the present embodiment, the plurality of force sensors 2 and the collection device 6 are connected by a star-shaped wiring.

  The collection device 6 is, for example, a data logger. The collection device 6 operates by being supplied with a DC voltage (for example, 12V) from a commercial power supply via an AC / DC converter, for example. Each of the plurality of force sensors 2 operates by being supplied with a DC voltage (for example, 5 V or 12 V) from the collecting device 6 via the power line 101. The plurality of force sensors 2 each output an output signal (for example, an analog voltage signal of 5 V) via the signal line 102.

  The collection device 6 collects detection data from the plurality of force sensors 2. In the force detection system 100 of the present embodiment, the collection device 6 has a detection circuit 3. In the collection device 6, the detection circuit 3 generates detection data based on the output signal of the force sensor 2. In other words, the collection device 6 collects the detection data from the plurality of force sensors 2 by taking the output signals of the plurality of force sensors 2 and generating the detection data by the detection circuit 3.

  Of course, the plurality of force sensors 2 may be a plurality of force detection devices 1 each including a detection circuit 3. In this case, the collection device 6 does not need to include the detection circuit 3. Then, the collection device 6 collects the detection data by taking in an output signal including the detection data from each of the plurality of force detection devices 1.

  The receiving terminal 7 is configured to be able to communicate with the collection device 6 by wire or wireless. That is, the collection device 6 and the receiving terminal 7 communicate via a network such as a wired LAN (Local Area Network) or a wireless LAN. Here, it is assumed that the collection device 6 and the reception terminal 7 are configured to be communicable by radio.

  The receiving terminal 7 receives a data signal including detection data collected by the collecting device 6. The receiving terminal 7 may be a communication device provided in the base station, for example. The receiving terminal 7 may be a communication device mounted on a patrol car F1 (see FIGS. 19A and 19B) that travels on, for example, a general road or an expressway. In addition, the receiving terminal 7 may be a portable terminal such as a smart phone or a tablet owned by the crew of the patrol car F1, for example.

  As described above, the force detection system 100 of this embodiment includes a plurality of force sensors 2. The plurality of force sensors 2 are attached to a plurality of screws (for example, bolts), respectively, and detect the looseness of the target screw by detecting the tightening axial force of the target screw. In other words, the force detection method of the present embodiment uses a plurality of force sensors 2 and attaches the plurality of force sensors 2 to a plurality of screws, respectively, and detects looseness of each of the plurality of screws.

  The force detection system 100 of the present embodiment can be used for monitoring a jet fan E11 attached to the ceiling in the tunnel E1, as shown in FIG. 19A, for example. The jet fan E11 is attached to the ceiling in the tunnel E1 using a plurality of anchor bolts (a plurality of screws) E12. The plurality of force sensors 2 are respectively attached to the plurality of anchor bolts E12. The collecting device 6 is attached to the inner wall of the tunnel E1.

  Here, the collection device 6 may be provided at a position where it can communicate wirelessly with the patrol car F1 traveling in the tunnel E1, and may not be attached to the inner wall of the tunnel E1. For example, the collection device 6 may be attached to a lighting fixture or a control panel provided in the tunnel E1. In this case, the lighting fixture and the control panel may have the function of the collecting device 6 without including the collecting device 6.

  Therefore, the force detection system 100 according to the present embodiment detects whether or not the jet fan E11 is normally attached to the ceiling by detecting looseness of a nut (screw) tightened to each of the plurality of anchor bolts E12. Can be monitored. Moreover, the force detection system 100 of this embodiment can also be used for monitoring the lighting fixture attached to the ceiling in the tunnel E1 instead of the jet fan E11.

  Moreover, the force detection system 100 of this embodiment can be used for monitoring of the information board G1 which notifies a congestion state or a construction notice on a general road or a highway as shown in FIG. 19B, for example. The information board G1 is attached to a support column G11 provided on a general road or an expressway using a plurality of bolts (a plurality of screws). The plurality of force sensors 2 are respectively attached to a plurality of bolts. The collection device 6 is attached to the column G11. Here, the collection device 6 may be provided at a position where it can communicate wirelessly with the patrol car F1 traveling on the road, and may be attached to the information board G1.

  Therefore, the force detection system 100 of the present embodiment detects whether or not the information board G1 is normally attached to the column G11 by detecting looseness of a nut (screw) that is tightened with respect to each of the plurality of bolts. Can be monitored. Note that the collection device 6 may not be configured to operate by supplying power from a commercial power source, but may be configured to operate by supplying power from a solar power source or a secondary battery, for example.

  By the way, the force detection system 100 of this embodiment may be provided with the some branching device 103, for example, as shown to FIG. 20A. The plurality of force sensors 2 may be connected to the collection device 6 by bus-type wiring that branches from one power line 101 connected to the collection device 6 via the branching device 103. Below, it demonstrates focusing on one branch device 103 of the some branch device 103, and the force sensor 2 connected to this branch device 103. FIG.

  The branching device 103 has a control device 104. The control device 104 is configured by mounting a microcomputer (microcomputer), input / output terminals, and the like on a substrate, for example. The control device 104 and the collection device 6 are electrically connected to each other by a power line 101 and a signal line 102. Further, the control device 104 and the force sensor 2 are electrically connected to each other by a power line 105 and a signal line 106. Therefore, the force sensor 2 operates by being supplied with a DC voltage via the power supply line 101, the control device 104, and the power supply line 105. The control device 104 has a function of capturing the output signal of the force sensor 2 via the signal line 106 and a function of transmitting the output signal captured via the signal line 102 to the collection device 6. Communication between the collection device 6 and the control device 104 is, for example, serial communication conforming to the communication standard RS-485.

  Moreover, the force detection system 100 of the present embodiment may include a plurality of PLC (Power Line Communication) modules 107 instead of the plurality of control devices 104, for example, as illustrated in FIG. 20B. The plurality of force sensors 2 may be configured to communicate with the collection device 6 by power line carrier communication via one power line 101 and a plurality of PLC modules 107, respectively. In this configuration, the signal line 102 is not necessary. In the example shown in FIG. 20B, the PLC module 107 to which the force sensor 2 is not connected functions as a repeater.

  In addition, as shown in FIG. 20C, for example, the force detection system 100 according to the present embodiment includes a single PLC module 107 and a plurality of force sensors 2 connected to the PLC module 107. (Instrument) 108 may be configured. In this configuration, since the electric device 108 replaces the branching device 103, the branching device 103 is not necessary. In the example shown in FIG. 20C, only one set of the power supply line 105 and the signal line 106 is shown, but actually, each of the plurality of force sensors 2 and the PLC module 107 are connected to the power supply line 105 and the signal line 106. Are electrically connected. In the example shown in FIG. 20C, the electric device 108 incorporates the plurality of force sensors 2 and the PLC module 107, but may have other configurations. For example, the configuration may be such that only the PLC module 107 is incorporated in the electric device 108 and the plurality of force sensors 2 are installed in a place different from the electric device 108.

  The force detection system 100 according to the present embodiment includes the collection device 6 and the reception terminal 7 in addition to the plurality of force sensors 2, but the collection device 6 and the reception terminal 7 are not essential configuration requirements. That is, the force detection system 100 of this embodiment should just be provided with the some force sensor 2, and it is arbitrary whether the collection apparatus 6 or the collection apparatus 6 and the receiving terminal 7 are further provided.

  For example, in addition to the plurality of force sensors 2, the force detection system 100 may further include a collection device 6 that collects detection data from each of the plurality of force sensors 2. The force detection system 100 may further include a receiving terminal 7 that receives a data signal including detection data collected by the collection device 6 in addition to the plurality of force sensors 2 and the collection device 6.

<Usage example of force sensor and force detection device>
The force sensor 2 and the force detection device 1 of the above-described Embodiments 1 to 3 and Modifications 1 to 5 are magnetostrictive. For this reason, the force sensor 2 and the force detection device 1 can be downsized while greatly reducing the cost, and a large load compared to the strain gauge type or piezoelectric type force sensor and force detection device. Can be detected. In particular, the force sensor 2 and the force detection device 1 are suitable for an object that is small and needs to detect a large load, such as the above-described bolt.

  The force sensor 2 and the force detection device 1 of the first to third embodiments and the first to fifth modifications are, for example, nuts that are tightened to the bolt or the shaft by detecting the tightening axial force of the bolt or the shaft. Looseness can be monitored. For example, the force sensor 2 and the force detection device 1 can monitor abnormalities such as nut loosening, breakage, and corrosion. Further, the force sensor 2 and the force detection device 1 can monitor abnormalities such as floating, cracks, and gaps in the surrounding concrete where the bolts are provided by detecting the abnormality of the bolts.

  In addition, the force sensor 2 and the force detection device 1 according to the first to third embodiments and the first to fifth modifications are used for mounting brackets such as a hanging bracket, a turnbuckle, a fixing bracket, an anchor bolt, a bolt and a nut, and a joint. it can. These mounting brackets are, for example, infrastructure accessories such as lights (lights, tunnel lights, etc.), information boards, signs, jet fans, cable racks, traffic lights, sound insulation walls, ceiling boards, slopes, rails, and sleepers. Can be used.

  These accessories can be used for infrastructure such as roads (road bridges, road tunnels, etc.), rivers, dams, sabos, coasts, sewers, ports, airports. In addition, these accessories can be used for infrastructures such as railways (railroad bridges, railway tunnels, railway tracks, railway electrical circuit equipment, etc.), navigation routes, parks, houses, plants, and power equipment (electric poles, steel towers, etc.). .

  Specifically, the force sensor 2 and the force detection device 1 can be used for a fixture for an information board of a road bridge, a turnbuckle of a jet fan in a road tunnel, and an anchor bolt on a slope of a dam. In addition, the force sensor 2 and the force detection device 1 can be used for lighting bolts and nuts of railway tunnels, railroad rail sleeper fixing brackets, sewer piping joint bolts, and park playground equipment mounting brackets.

  Furthermore, the force sensor 2 and the force detection device 1 according to the first to third embodiments and the first to fifth modifications are not limited to the infrastructure field, and can be used in, for example, the industrial field and the consumer field. In the industrial field, for example, the force sensor 2 and the force detection device 1 can be used for industrial equipment, industrial robots, trucks, elevators, ships, building scaffolds, temporary facilities, and the like. In the consumer field, for example, the force sensor 2 and the force detection device 1 can be used for consumer devices, consumer robots, play equipment (for example, roller coasters), and the like.

  In addition, the force sensor 2 and the force detection device 1 of the first to third embodiments and the first to fifth modifications are not limited to applications for detecting the tightening axial force of a bolt or a shaft, and may be other applications. For example, the force sensor 2 and the force detection device 1 are also suitable for applications that detect tension applied to an object. Specifically, the force sensor 2 and the force detection device 1 can be used for monitoring whether or not an object suspended by a cable or the like is normally fixed, or for monitoring a suspension bridge cable.

  In addition, the force sensor 2 and the force detection device 1 according to the first to third embodiments and the first to fifth modifications are also suitable for applications that detect the weight of an object. Specifically, the force sensor 2 and the force detection device 1 can be used for detecting the weight of an object stored in a bottle, bag, tank, or the like, or detecting whether or not the object is overloaded.

  In addition, the force sensor 2 and the force detection device 1 of the first to third embodiments and the first to fifth modifications are also suitable for applications that detect pressure applied to an object. Specifically, the force sensor 2 and the force detection device 1 can be used for detection of pressure applied to the object by the press machine and detection of pressure when the extruder melts and extrudes the object.

  Moreover, the force sensor 2 and the force detection apparatus 1 of Embodiments 1-3 and the modifications 1-5 are suitable also for the use which detects the load added to a target object. Specifically, the force sensor 2 and the force detection device 1 can be used to detect a load applied to a warm water toilet seat, a care bed, a touch pen, and a switch.

  Moreover, the force sensor 2 and the force detection apparatus 1 of Embodiments 1-3 and the modifications 1-5 are suitable also for the use which detects the grip force added to a target object. Specifically, the force sensor 2 and the force detection device 1 can be used to detect a gripping force applied to an electric driver, an electric toothbrush, a pachinko handle, a fishing rod, a motorcycle brake, and a motorcycle throttle.

  In addition, the force sensor 2 and the force detection device 1 according to the first to third embodiments and the first to fifth modifications are also suitable for applications that detect a pedaling force applied to an object. Specifically, the force sensor 2 and the force detection device 1 can be used to detect a pedaling force applied to an accelerator or a brake of an automobile.

DESCRIPTION OF SYMBOLS 1 Force detection apparatus 2 Force sensor 20 Detection part 21 1st structure 22 2nd structure 210,220 Through-hole 223,224 1st protrusion 213,214 2nd protrusion 215,225 Convex part 216,226 Concave part 217,227 Insertion Hole 21A, 22A Edge 220A Female thread (screw)
23 Elastic body 25 Third structure 26 Fourth structure 26A Female thread (screw)
27 pin 3 detection circuit 36 substrate 37 housing 4 core 40 hollow part 5 coil 6 collecting device 7 receiving terminal 100 force detection system E12 anchor bolt (screw)
S1 Suppression structure S11 to S15 Stopper

Claims (21)

A core formed of a magnetic material, and a coil that is magnetically coupled to the core, and a magnetic flux generated by the coil when energized passes through the core; and
A first structure and a second structure respectively disposed on both sides in a predetermined detection direction of the core;
An elastic body provided between the outer peripheral edge of the first structure and the outer peripheral edge of the second structure, joined to both, and formed of a material having a lower elastic modulus than the core;
The force sensor is configured to receive a load applied from the first structure and the second structure in a direction along the detection direction.   The force sensor according to claim 1, further comprising a suppression structure that suppresses relative rotation of the first structure and the second structure around an axis along the detection direction.   3. The force sensor according to claim 2, wherein the first structure and the second structure are each formed in a non-circular shape when viewed from the detection direction.   4. The force sensor according to claim 3, wherein each of the first structure and the second structure is formed in a square shape when viewed from the detection direction.   The force sensor according to claim 2, wherein the first structure and the second structure each include a stopper that is abutted in the direction of rotation as the restraining structure.   The stopper includes a first protrusion that protrudes from one outer peripheral edge of either the first structure or the second structure, and a pair of second protrusions that protrude from the other outer peripheral edge and sandwich the first protrusion. The force sensor according to claim 5, wherein:   The stopper is composed of a convex portion protruding from one outer peripheral edge of the first structure and the second structure, and a concave portion provided on the other outer peripheral edge into which the convex portion is fitted. The force sensor according to claim 5. The first structure and the second structure are provided with insertion holes that continuously penetrate in the detection direction,
The force sensor according to claim 5, wherein the stopper includes the insertion hole and a pin that is inserted into the insertion hole.   The edge part which protrudes in the said detection direction in the said detection direction from the at least one outer periphery of the said 1st structure and the said 2nd structure is further provided in any one of Claim 2 thru | or 8 characterized by the above-mentioned. The force sensor described.   10. The force sensor according to claim 9, wherein one of the first structure and the second structure is a plate-like lid that closes an opening surrounded by the other edge.   The force sensor according to claim 9 or 10, wherein the first structure and the second structure have the same structure.   The force sensor according to any one of claims 9 to 11, wherein the edge portion includes a third structure that is separate from the first structure and the second structure. The core has a hollow portion;
The force according to claim 12, further comprising a fourth structure that covers an inner peripheral surface of the core and is separate from the first structure, the second structure, and the third structure. Sensor. Each of the first structure and the second structure has a through hole penetrating in the detection direction continuously with the hollow portion,
A screw is formed on at least one of the peripheral surface of the through hole of the first structure, the peripheral surface of the through hole of the second structure, and the inner peripheral surface of the fourth structure. The force sensor according to claim 13.   15. A force detection apparatus comprising: the force sensor according to claim 1; and a detection circuit that detects a load based on a change in magnetic characteristics of the coil.   The force detection device according to claim 15, wherein the detection circuit is mounted on a substrate housed in a space surrounded by the first structure, the second structure, and the elastic body. The detection circuit is housed in a housing;
The force detection device according to claim 15, wherein the casing is detachably attached to the force sensor.   A plurality of force sensors according to any one of claims 1 to 14, wherein the plurality of force sensors are attached to a plurality of screws, respectively, and detect looseness of each of the plurality of screws. Force detection system.   The force detection system according to claim 18, further comprising a collection device that collects detection data from the plurality of force sensors.   The force detection system according to claim 19, further comprising a reception terminal that receives a data signal including detection data collected by the collection device.   A plurality of force sensors according to any one of claims 1 to 14, wherein the plurality of force sensors are respectively attached to a plurality of screws to detect looseness of each of the plurality of screws. Force detection method.

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