JP5866515B2 - Force sensor and force detection device using the same - Google Patents

Description

  The present invention generally relates to a force sensor and a force detection device, and more particularly to a force sensor that detects a load applied to a magnetic body by using the inverse magnetostriction effect of the magnetic body and a force detection apparatus 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 and disclosed in, for example, Patent Document 1. The conventional example described in Patent Document 1 includes a plurality of ring-shaped outer periphery fixing portions in plan view, a load applying portion located at the center inside the outer periphery fixing portion, and a plurality of outer periphery fixing portions and load applying 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 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 of the present invention is to provide a force sensor that can be thinned and a force detection device using the force sensor.

The force sensor of the present invention, as to sandwich the detection section having a core that is formed of a magnetic material having a hollow portion, and said core and magnetically coupled to the coil, the detection portion from both sides of the predetermined detection direction A first plate and a second plate disposed on the core; and an elastic body formed of a material having a lower elastic modulus than the core, and positioning between the first plate and the second plate. Is configured to receive a load applied from the first plate and the second plate in a direction along the detection direction, and a magnetic path through which a magnetic flux generated by a current flowing through the coil passes is provided in the core. The elastic body is bonded to the outer peripheral edge of the first plate and the outer peripheral edge of the second plate, so that the first plate and the second plate can As it sandwiched from both sides of knowledge direction, and which are located between the first plate and the second plate.

  The force sensor preferably includes a plurality of the detection units, and the plurality of detection units are arranged along a plane orthogonal to the detection direction.

  In this force sensor, the plurality of detection units are preferably arranged symmetrically with respect to a reference line on the plane or point-symmetrically with respect to a reference point on the plane.

  In this force sensor, it is preferable that the first plate and the second plate each have a through hole penetrating in the detection direction, and the plurality of detection units are arranged around the through hole.

  In this force sensor, it is preferable that the plurality of detection units are arranged in a one-to-one correspondence with two or more detection positions selected from a plurality of detection positions.

  In this force sensor, it is preferable that the cores of each of the plurality of detection units have the same size in the detection direction.

  The force sensor preferably includes a structure that is disposed between the first plate and the second plate and positions the detection unit.

  In this force sensor, it is preferable that the structure has a positioning hole penetrating in the detection direction, and the core is disposed inside the positioning hole.

  In this force sensor, the structure is preferably a substrate on which a circuit is formed.

  The force sensor includes an insulator that is disposed between an outer shell including at least one of the first plate and the second plate and the substrate and electrically insulates the outer shell from the substrate. Is preferred.

  A force detection apparatus according to the present invention includes any one of the force sensors described above and a detection circuit that detects a load based on a change in magnetic characteristics of the coil.

  In the present invention, the detection unit is sandwiched between the first plate and the second plate, and both the first plate and the second plate are positioned by an elastic body. For this reason, in the present invention, it is not necessary to provide the first plate and the second plate with the strain-generating portion as in the conventional example, so that the thickness dimension of the first plate and the second plate can be reduced. it can. Therefore, according to the present invention, it is possible to reduce the thickness by reducing the dimension in the thickness direction of the first plate and the second plate.

1A is a schematic diagram illustrating a force sensor and a force detection device according to Embodiment 1, FIG. 1B is a plan view of the force sensor according to Embodiment 1, and FIG. 1C is a cross-section of the force sensor according to Embodiment 1. FIG. FIG. 3 is a schematic diagram of a detection circuit in the force detection device according to the first embodiment. FIG. 3A is a diagram illustrating a magnetic flux distribution of an open magnetic circuit in a core having a hollow portion, and FIG. 3B is a diagram illustrating a magnetic flux distribution of an open magnetic circuit in a core having no hollow portion. 4 is a cross-sectional view showing a configuration using a structure other than a substrate in the force sensor according to Embodiment 1. FIG. 5A is a cross-sectional view of the force sensor according to the second embodiment, and FIG. 5B is a plan view of the force sensor according to the second embodiment. FIG. 6A is a plan view illustrating an example of a substrate in the force sensor according to the second embodiment. FIG. 6B is a plan view illustrating an example of a substrate in the force sensor according to the second embodiment. FIG. 7A is a schematic diagram illustrating an example in which each detection unit is individually connected to a detection circuit in the force detection device according to the second embodiment. FIG. 7B is a diagram illustrating each detection unit in the force detection device according to the second embodiment. It is the schematic which shows an example connected individually to the detection circuit. In the force detection apparatus which concerns on Embodiment 2, it is the schematic which shows an example which connected each detection part to the detection circuit in series. 6 is a schematic diagram illustrating an example of use of a force sensor according to Embodiment 2. FIG. FIG. 10A is a plan view illustrating an example of the arrangement of the detection units in the force sensor according to the second embodiment, and FIG. 10B is a plan view illustrating an example of the arrangement of the detection units in the force sensor according to the second embodiment. FIG. 11A is a plan view illustrating an example in which a detection unit is arranged on a square substrate in the force sensor according to the second embodiment, and FIG. 11B is a semicircular shape in plan view in the force sensor according to the second embodiment. FIG. 11C is a plan view illustrating an example in which the detection unit is arranged on an annular substrate in plan view in the force sensor according to the second embodiment. In the force sensor which concerns on Embodiment 2, it is sectional drawing which shows an example which has arrange | positioned the insulator. In the force sensor which concerns on Embodiment 2, it is a top view which shows an example which formed the coil in the board | substrate. In the force sensor which concerns on Embodiment 2, it is sectional drawing which shows an example which provided the recessed part instead of the positioning hole. In the force sensor which concerns on Embodiment 2, it is sectional drawing which shows an example which has arrange | positioned the rigid body. 16A is a cross-sectional view illustrating a configuration using a structure other than the substrate in the force sensor according to the second embodiment. FIG. 16B illustrates a configuration using a structure other than the substrate in the force sensor according to the second embodiment. FIG. 17A is a cross-sectional view illustrating another configuration using a structure other than the substrate in the force sensor according to Embodiment 2, and FIG. 17B uses the structure other than the substrate in the force sensor according to Embodiment 2. It is a top view which shows the other structure which was.

(Embodiment 1)
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 plate 21 and a second plate 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. The first plate 21 and the second plate 22 are arranged so as to sandwich the detection unit 20 from both sides in a predetermined detection direction. The elastic body 23 is formed of a material having a lower elastic modulus than the core 4 and positions between the first plate 21 and the second plate 22. The detection unit 20 is configured to receive a load applied from the first plate 21 and the second plate 22 in a direction along the detection direction.

  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.

  Hereinafter, the force sensor 2 and the force detection device 1 of the present embodiment will be described in detail. However, the configuration described below is only an example of the present invention, and the present invention is not limited to the following embodiment, and the technical idea according to the present invention is not deviated from this embodiment. Various changes can be made in accordance with the design or the like as long as they are not. In the following description, the thickness direction (detection direction) of the core 4 is assumed to be the vertical direction, and the first plate 21 side is assumed to be the lower side and the second plate 22 side is assumed to be the upper side when viewed from the core 4. And it is not the meaning which limits the usage form of the force detection apparatus 1. FIG.

  The force detection apparatus 1 of this embodiment is provided with the force sensor 2 and the detection circuit 3, as shown to FIG. 1A. In addition, as shown in FIGS. 1A to 1C, the force sensor 2 of the present embodiment includes a detection unit 20, a first plate 21, a second plate 22, an elastic body 23, a substrate (structure) 24, and the like. It has. In addition, illustration of the 2nd plate 22 and the elastic body 23 is abbreviate | omitted in FIG. 1B.

  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. In the force sensor 2 of the present embodiment, 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 plate 21 and the second plate 22 are both plate-like members formed of, for example, a metal material. As shown in FIG. 1B, the first plate 21 is formed in a circular shape in plan view. In addition, although not shown, the second plate 22 is formed in a circular shape in a plan view like the first plate 21. As shown in FIG. 1C, the first plate 21 is disposed on the lower side of the core 4 in contact with the lower surface of the core 4. Moreover, the 2nd plate 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 plate 21 and the second plate 22 are arranged so as to sandwich the core 4 from both sides in the vertical direction (detection direction).

  In addition, the shape of the 1st plate 21 and the 2nd plate 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 plate 21 and the 2nd plate 22 should just have the intensity | strength which can endure the assumed load. Further, the first plate 21 and the second plate 22 may not be formed of a metal material, and may be formed of a resin material such as CFRP (Carbon-Fiber-Reinforced Plastic).

  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 plate 21 and the second plate 22 to each other by adhering to the outer peripheral edge of the upper surface of the first plate 21 and the outer peripheral edge of the lower surface of the second plate 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 which positions between both the 1st plate 21 and the 2nd plate 22. FIG.

  As shown in FIG. 1C, the substrate 24 is accommodated in a space surrounded by the first plate 21, the second plate 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. 1C, 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 other words, the substrate (structure) 24 is a member that is disposed between the first plate 21 and the second plate 22 and positions the detection unit 20 at a predetermined position. The substrate (structure) 24 has a positioning hole 240 penetrating in the vertical direction (detection direction). The core 4 is disposed inside the positioning hole 240. 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 50 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 50. 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 50 includes a series circuit of an inductor L1 and a resistor R1, and a parallel circuit of a capacitor C1. Here, the inductance of the inductor L1 is equivalent to the inductance of the coil 5. Further, the resistance value of the resistor R1 is equivalent to the resistance value of the winding resistance of the coil 5. Further, the capacitance value of the capacitor C1 is equivalent to the capacitance value of the parasitic capacitance of the coil 5. The resonance circuit 50 may be configured by electrically connecting a capacitor (not shown) 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. In other words, a circuit (detection circuit 3) is formed on the substrate (structure) 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, for example, on a substrate (not shown) outside the force sensor 2. 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 to the coil 5 from an external power source (not shown), 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 plate 21 (see the upward arrow shown in FIG. 1C), the first plate 21 is pushed up by the elastic body 23 being bent, and the first plate 21 is A load is applied to the core 4. Then, due to the inverse magnetostriction 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 downward load is applied to the upper surface of the second plate 22 (see the downward arrow shown in FIG. 1C), the second plate 22 is pushed down by the elastic body 23 being bent, and the second plate 22 passes through the second plate 22. A load is applied to the core 4. 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 plate 21 and the second plate 22 in a direction along the vertical direction (detection direction). .

  When the inductance of the coil 5 changes, the resonance frequency of the resonance circuit 50 including the coil 5 changes. Therefore, the oscillation circuit 30 outputs an oscillation signal having a frequency corresponding to the resonance frequency of the resonance circuit 50, 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 L1 and the capacitance value of the capacitor C1 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 sandwiches the detection unit 20 between the first plate 21 and the second plate 22, and positions both the first plate 21 and the second plate 22 with the elastic body 23. It has a configuration. For this reason, in the force sensor 2 according to the present embodiment, the first plate 21 and the second plate 22 do not need to be provided with a strain generating portion as in the conventional example. The vertical dimension can be reduced. Therefore, the force sensor 2 of the present embodiment can be reduced in thickness by reducing the thickness dimension of the first plate 21 and the second plate 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 plate 21 or the second plate 22.

  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. However, as shown in FIG. You may be comprised by winding along the outer periphery of the core 4. FIG. In this configuration, the magnetic flux generated when the coil 5 is energized forms a magnetic path M <b> 2 that passes not only inside the core 4 but also outside the core 4. That is, in this configuration, the magnetic path M2 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 as illustrated in FIG. 3B.

  Further, in the force sensor 2 of the present embodiment, the core 4 is positioned using the substrate 24. For example, as shown in FIG. 4, the core 4 is positioned by a structure 27 other than the substrate 24. Also good. In this configuration, the first plate 21 is provided with a circular through-hole 210 in the center in a plan view. Similarly, in this configuration, the second plate 22 is provided with a circular through-hole 220 in the center in a plan view. These 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 when detecting the tightening axial force of a bolt (not shown). Further, these through holes 210 and 220 pass the tendon 102A (see FIG. 9) of the anchor 100 through the hollow portion 40 of the core 4 when detecting the tensile force of the anchor 100 (see FIG. 9). Used for. Of course, the shape of the through-holes 210 and 220 is not limited to a circular shape in plan view, and may be any shape as long as it allows the shaft portion of the bolt and the tendon 102A to pass therethrough.

  The structure 27 is formed in a sheet shape from, for example, a metal material or a resin material, and is housed in a space surrounded by the first plate 21, the second plate 22, and the elastic body 23. The structure 27 is fixed by filling the elastic body 23 in a part of the space. The structure 27 is formed in an annular shape in a plan view like the substrate 24, and a central portion thereof is an annular positioning hole 270 in the plan view. The core 4 is positioned at a predetermined position by fitting the core 4 into the positioning hole 270. The shape of the positioning hole 270 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 270 only needs to have a shape into which the core 4 is fitted.

  In this configuration, the force sensor 2 does not include the substrate 24. That is, the detection circuit 3 is disposed outside the force sensor 2. Therefore, in this configuration, since it is not necessary to design a circuit such as the detection circuit 3 in the structure 27, the dimension in the thickness direction of the structure 27 can be reduced as compared with the substrate 24. Therefore, the force sensor 2 can be reduced in thickness.

  In addition, in the force sensor 2 of this embodiment, it is arbitrary whether the board | substrate 24 and the structure 27 are provided. That is, the force sensor 2 of the present embodiment does not have to be provided with the substrate 24 and the structure 27 as long as the core 4 is positioned by the first plate 21 and the second plate 22 and the elastic body 23. However, if the configuration includes the substrate 24 and the structure 27, there is no need to provide a structure for positioning the core 4 by processing the first plate 21 and the second plate 22, and the first plate 21 and the second plate. There is an advantage that the thickness dimension of 22 can be reduced.

  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.

(Embodiment 2)
The force sensor 2 and the force detection device 1 according to the present embodiment 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 (here, twelve) detection units 20, a first plate 21, a second plate 22, an elastic body 23, And a substrate (structure) 24. Moreover, the some detection part 20 is arrange | positioned along the plane orthogonal to an up-down direction (detection direction). In FIG. 5B, the second plate 22 and the elastic body 23 are not shown. Further, “orthogonal” is an expression including “substantially orthogonal” as well as complete “orthogonal”.

  As shown in FIG. 5B, the first plate 21 is formed in a square shape in plan view. Although not shown, the second plate 22 is formed in a square shape in a plan view like the first plate 21. As shown in FIG. 5A, the first plate 21 is disposed below the plurality of cores 4 so as to be 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 plate 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 plate 21 and the second plate 22 are arranged so as to sandwich the plurality of cores 4 from both sides in the vertical direction (detection direction).

  As shown in FIGS. 5A and 5B, the first plate 21 is provided with a circular through hole 210 in a plan view that penetrates the center portion in the vertical direction (detection direction). Further, as shown in FIG. 5A, the second plate 22 is provided with a circular through hole 220 in a plan view that penetrates the center portion in the vertical direction (detection direction). Of course, the shape of the through-holes 210 and 220 is not limited to a circular shape in plan view, and may be any shape as long as it allows the shaft portion of the bolt and the tendon 102A to pass therethrough.

  In the force sensor 2 of the present embodiment, the through hole 210 is provided in the central portion of the first plate 21 and the through hole 220 is provided in the central portion of the second plate 22, but the positions where the through holes 210 and 220 are provided. It is not intended to limit. That is, the through-hole 210 may be provided so as to penetrate the first plate 21 in the vertical direction (detection direction), and the position thereof is not limited to the central portion. Similarly, the through hole 220 may be provided so as to penetrate the second plate 22 in the vertical direction (detection direction), and the position thereof is not limited to the central portion.

As shown in FIG. 5A, the elastic body 23 is bonded to the outer peripheral edge of the upper surface of the first plate 21 and the outer peripheral edge of the lower surface of the second plate 22, thereby connecting the first plate 21 and the second plate 22 to each other. Join. 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 plate 21 and the periphery of the through hole 220 on the lower surface of the second plate 22, thereby 21 and the second plate 22 are coupled to each other.
That is, the elastic body 23 may be configured to position both the first plate 21 and the second plate 21.

  As shown in FIG. 5A, the substrate 24 is accommodated in a space surrounded by the first plate 21, the second plate 22, and the elastic body 23. The board | substrate 24 is formed in square shape by planar view, as shown to FIG. 5B. In addition, a circular through hole 241 is provided in a central portion 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 any shape that allows the shaft portion of the bolt and the tendon 102A to pass therethrough. The substrate 24 is fixed so that the outer peripheral edge thereof and the inner peripheral edge of the through hole 241 are in contact with the elastic body 23.

  Further, as shown in FIGS. 5B and 6A, the substrate 24 is provided with a plurality of (in the figure, 12) 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 a plan view, and may be a rectangular shape in a plan view as shown in FIG. 6B, for example. That is, the positioning hole 240 may have a shape into which the core 4 is fitted.

  In the force sensor 2 of the present embodiment, as shown in FIG. 5B, each positioning hole 240 is symmetrical with respect to a reference line R1 passing through the center of the through hole 241 in a plane orthogonal to the vertical direction (detection direction). It is arranged to become. Each positioning hole 240 is arranged to be point-symmetric with respect to the reference point R2 with the center of the through hole 241 as the reference point R2 in a plane orthogonal to the vertical direction (detection direction). Therefore, by arranging the core 4 in each positioning hole 240, each detection unit 20 is also arranged so as to be symmetric with respect to the reference line R1, and arranged so as to be symmetric with respect to the reference point R2. Is done. In other words, the plurality of detection units 20 are arranged around the through holes 210 and 220.

  In the force detection device 1 of the present embodiment, as shown in FIG. 7A, each detection unit 20 is electrically connected to the detection circuit 3 individually. That is, both ends of each coil 5 are individually electrically connected to the detection circuit 3. The detection circuit 3 can detect the load applied to all the cores 4 (that is, the load applied to the force sensor 2) by calculating based on the total value of the output signal levels of the detection units 20.

  The detection circuit 3 can also calculate a load applied to each detection unit 20 based on the level of the output signal of each detection unit 20. In this configuration, the detection circuit 3 can detect the distribution of the load applied to the first plate 21 or the second plate 22 by comparing the load applied to each detection unit 20. That is, in this configuration, it is possible to detect whether a load is uniformly applied to the first plate 21 or the second plate 22.

  In this configuration, as shown in FIG. 7B, the detection circuit 3 can detect a load even when there is a detection unit 20 that does not include the coil 5. Therefore, in this configuration, the number of detection units 20 can be reduced according to the detection target, and the manufacturing cost can be reduced.

  Moreover, the structure which connected each detection part 20 to the detection circuit 3 in series electrically may be sufficient as the force detection apparatus 1 of this embodiment, as shown in FIG. That is, both ends of the series circuit of each coil 5 are electrically connected to the detection circuit 3. In this configuration, even if the level of the output signal of one detection unit 20 is very small, the detection circuit 3 calculates the load based on the total value of the levels of the output signals of all the detection units 20. There is an advantage that accuracy is improved. In addition, this configuration has an advantage that mutual interference hardly occurs between the adjacent coils 5.

  Hereinafter, the Example which detects the tensile force of the anchor 100 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. 9, the detection circuit 3 is not shown. The anchor 100 is used to transmit a tensile force from the structure A1 to the ground (not shown). The anchor 100 includes an anchor body (not shown) having a function of transmitting a tensile force to the ground, an anchor head 101 for coupling the anchor 100 to the structure A1, and an tensile force from the anchor head 101. It is comprised with the tension | pulling part 102 transmitted to a body.

  The anchor head 101 includes a nut 101A that is a fixing tool, and an anchor plate 101B that is a pressure bearing plate disposed on the structure A1. The anchor plate 101B is provided with a hole 101C through which the tendon 102A can pass. The tension portion 102 includes a rod-shaped tendon 102A made of, for example, a PC (Prestressed Concrete) steel strand. An anchor body is mechanically connected to the first end in the longitudinal direction of the tendon 102A. Further, the second end in the longitudinal direction of the tendon 102A is tightened with the nut 101A while being passed through the hole 101C of the anchor plate 101B and the through holes 210, 220, and 241 of the force sensor 2 of the present embodiment. .

  The force sensor 2 according to the present embodiment is arranged in such a manner as to be sandwiched between the nut 101A and the anchor plate 101B. Therefore, the force detection device 1 according to the present embodiment can detect the tensile force of the anchor 100 when the detection circuit 3 detects a load in which the nut 101A 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, even when the force sensor 2 and the force detection device 1 of the present embodiment are used for a large member such as the anchor 100, it is possible to reduce the thickness.

  In the force sensor 2 of the present embodiment, the cores 4 (that is, the cores 4 included in each of the plurality of detection units 20) have the same dimension in the thickness direction (see “T1” in FIG. 5A). Yes. For this reason, the force sensor 2 according to the present embodiment has the advantage that the surfaces perpendicular to the thickness direction of the cores 4 are aligned with each other, and therefore, it is easy to apply a load evenly to the cores 4 and an uneven load hardly occurs. “Equal” is an expression including “same” or “substantially identical”. Therefore, it is an error within an allowable range that the dimension in the thickness direction of each core 4 is slightly different from each other due to a manufacturing error. Note that whether or not the cores 4 have the same thickness in the thickness direction is arbitrary.

  Further, in the force sensor 2 of the present embodiment, as shown in FIG. 5B, the detectors 20 are arranged so as to be line-symmetric with respect to the reference line R1, and are point-symmetric with respect to the reference point R2. Is arranged. For this reason, in the force sensor 2 of the present embodiment, the cores 4 are evenly distributed on a plane (for example, a plane parallel to the lower surface of the first plate 21 and the upper surface of the second plate 22) perpendicular to the vertical direction (detection direction). Since they are arranged, there is an advantage that a load is easily applied evenly to each core 4 and an uneven load is hardly generated.

  In the force sensor 2 of the present embodiment, for example, as illustrated in FIG. 10A, each detection unit 20 may be disposed along a diagonal line of the substrate 24. Even in this configuration, the detection units 20 are arranged in line symmetry with respect to the reference line R1 and are arranged in point symmetry with respect to the reference point R2. Each detection unit 20 may be arranged so as to be line-symmetric with respect to the reference line R1, but not point-symmetric with respect to the reference point R2. Furthermore, each detection unit 20 may be arranged so as to be point-symmetric with respect to the reference point R2, although it is not line-symmetric with respect to the reference line R1.

  In addition, each detection part 20 may be selectively arrange | positioned in any of the some positioning hole 240, for example, as shown to FIG. 10B. In other words, the plurality of detection units 20 may be arranged in a one-to-one correspondence with two or more detection positions selected from a plurality of detection positions (here, the positioning holes 240). Moreover, each detection part 20 may be arrange | positioned asymmetrically with respect to any of the reference line R1 and the reference point R2, similarly as shown to FIG. 10B. In addition, in FIG. 10A and FIG. 10B, illustration of the 2nd plate 22 and the elastic body 23 is abbreviate | omitted, respectively.

  Further, in the force sensor 2 of the present embodiment, the first plate 21 is provided with the through hole 210, the second plate 22 is provided with the through hole 220, and the substrate 24 is provided with the through hole 241, but the through holes 210, 220, and 241 are provided. Whether or not is provided is arbitrary. That is, the force sensor 2 of the present embodiment has a configuration in which a plurality (9 in the drawing) of detection units 20 are arranged on a square substrate 24 in a plan view that does not have the through-hole 241 as illustrated in FIG. 11A, for example. It may be. In this configuration, the first plate 21 and the second plate 22 also do not have the through holes 210 and 220, respectively.

  Further, the force sensor 2 of the present embodiment includes the first plate 21 and the second plate 22 and the substrate 24 that are square in a plan view, but the first plate 21, the second plate 22, and the substrate 24 are It is not intended to limit the shape. That is, the force sensor 2 of the present embodiment may include a first plate 21 and a second plate 22 and a substrate 24 that are semicircular in a plan view as shown in FIG. 11B, for example. In addition, as shown in FIG. 11C, the force sensor 2 of the present embodiment may include a first plate 21 and a second plate 22 and a substrate 24 that are annular in a plan view. In addition, in FIG. 11A-FIG. 11C, illustration of the 2nd plate 22 and the elastic body 23 is abbreviate | omitted, respectively.

  Further, as shown in FIG. 12, the force sensor 2 of the present embodiment is disposed between the outer shell including at least one of the first plate 21 and the second plate 22 and the substrate 24, and The structure provided with the insulator 25 which electrically insulates between may be sufficient. In the example shown in FIG. 12, the outer shell is the first plate 21. The insulator 25 is an adhesive made of a material having elasticity and insulation, for example. In this configuration, the insulation between the first plate 21 (or the second plate 22) and the substrate 24 on which a circuit such as the detection circuit 3 is designed can be improved. This is particularly effective when the first plate 21 (or the second plate 22) is formed of a metal material. Therefore, in this configuration, it is not necessary to provide a spacer in order to secure an insulating distance between the first plate 21 (or the second plate 22) and the substrate 24, and a bolt for fixing the spacer is not necessary. Therefore, the enlargement of the force sensor 2 can be avoided.

  The insulator 25 may be an insulating sheet formed of an insulating material or a coating agent formed of an insulating material and applied to one surface of the substrate 24. Moreover, the structure which provided the insulator 25 in both between the 1st plate 21 and the board | substrate 24 and between the 2nd plate 22 and the board | substrate 24 may be sufficient. That is, both the first plate 21 and the second plate 22 may be outlines. Note that whether or not the insulator 25 is provided is arbitrary. For example, if the force sensor 2 of the present embodiment is configured not to include the substrate 24 on which the circuit such as the detection circuit 3 is designed, the insulator 25 need not be provided.

  Further, as shown in FIG. 13, the force sensor 2 of the present embodiment may have a configuration in which the coil 5 is provided by patterning a conductor along the circumferential direction of the positioning hole 240 of the substrate 24. The coil 5 is configured by patterning a conductor on either the upper surface or the lower surface of the substrate 24. If the substrate 24 is a multilayer substrate, the coil 5 is configured by patterning a conductor on any layer of the substrate 24. In this configuration, since the coil 5 is provided on the substrate 24, it is not necessary to wind a conducting wire around the core 4. For this reason, the core 4 does not need to have a thickness dimension required in order to wind a conducting wire. That is, this configuration can reduce the thickness of the core 4. In addition, in this structure, since it is not necessary to wind a conducting wire around the core 4, the core 4 which does not have the hollow part 40 is used, but the core 4 which has the hollow part 40 may be used.

  The force sensor 2 of the present embodiment has a configuration in which the positioning hole 240 is provided in the substrate 24, but may have a configuration in which a concave portion 242 is provided instead of the positioning hole 240 as shown in FIG. As shown in FIG. 14, the recess 242 is formed in a shape recessed downward from the upper surface of the substrate 24. In addition, the shape of the recessed part 242 should just be a shape in which the core 4 fits in, and the opening may be circular shape in planar view, and another shape may be sufficient as it. Even in this configuration, the core 4 can be positioned at a predetermined position by disposing the core 4 inside the recess 242. The force sensor 2 according to the first embodiment may also have a configuration in which the concave portion 242 is provided in the substrate 24 instead of the positioning hole 240.

  Further, as shown in FIG. 15, the force sensor 2 of the present embodiment may have a configuration in which an elastic body 23 is provided so as to sandwich the rigid body 26 from both sides in the vertical direction (detection direction). The rigid body 26 is made of a material having higher rigidity than the elastic body 23 such as a metal material. In this configuration, the strength of the elastic body 23 with respect to the load can be improved as compared with the case where the rigid body 26 is not provided. The thickness of the rigid body 26 is preferably adjustable according to the thickness of the core 4. Further, the configuration shown in FIG. 15 is a configuration in which the rigid body 26 is provided on the outer elastic body 23, but may be a configuration in which the rigid body 26 is also provided on the inner elastic body 23.

  Furthermore, the force sensor 2 of the present embodiment may be configured to position the core 4 with a structure 27 other than the substrate 24, as with the force sensor 2 of the first embodiment (see FIGS. 16A and 16B). In addition, in FIG. 16B, illustration of the 2nd plate 22 and the elastic body 23 is abbreviate | omitted. The structure 27 is accommodated in a space surrounded by the first plate 21 and the second plate 22 and the elastic body 23. The structure 27 is fixed by filling the elastic body 23 in a part of the space.

  Similar to the substrate 24, the structure 27 is formed in a square shape in plan view. As shown in FIG. 16B, a circular through hole 271 in a plan view having a diameter dimension (for example, a diameter of 140 mm) slightly larger than the diameter dimension of the through holes 210 and 220 is provided in the central portion of the structure 27. It has been. Similar to the through holes 210 and 220, the through hole 271 may have a shape that allows the shaft portion of the bolt and the tendon 102A to pass therethrough. Further, as shown in FIG. 16B, the structure 27 is provided with a plurality (12 in the drawing) of positioning holes 270 around the through hole 271. Each positioning hole 270 is formed in a circular shape in plan view, and is provided at equal intervals along the circumferential direction of the through hole 271. The shape of the positioning hole 270 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 270 only needs to have a shape into which the core 4 is fitted.

  In this configuration, as in the case of the force sensor 2 of the first embodiment, it is not necessary to design a circuit such as the detection circuit 3 in the structure 27. Since it can be made small, the force sensor 2 can be made thin.

  Furthermore, the force sensor 2 of the present embodiment may have a structure in which the structure 27 is formed integrally with the first plate 21 (or the second plate 22), as shown in FIGS. 17A and 17B. In FIG. 17B, the second plate 22 and the elastic body 23 are not shown. The structure 27 is formed integrally with the first plate 21 (or the second plate 22) by a processing technique such as welding. Even with this configuration, the force sensor 2 can be thinned.

  In addition, in the force sensor 2 of this embodiment, it is arbitrary whether the board | substrate 24 and the structure 27 are provided similarly to the force sensor 2 of Embodiment 1. FIG. That is, the force sensor 2 of the present embodiment does not have to be provided with the substrate 24 and the structure 27 as long as the core 4 is positioned by the first plate 21 and the second plate 22 and the elastic body 23. However, if the configuration includes the substrate 24 and the structure 27, there is no need to provide a structure for positioning the core 4 by processing the first plate 21 and the second plate 22, and the first plate 21 and the second plate. There is an advantage that the thickness dimension of 22 can be reduced.

DESCRIPTION OF SYMBOLS 1 Force detection apparatus 2 Force sensor 20 Detection part 21 1st plate 210 Through-hole 22 2nd plate 220 Through-hole 23 Elastic body 24 Board | substrate (structure)
240 Positioning hole 25 Insulator 27 Structure 270 Positioning hole 3 Detection circuit 4 Core 5 Coil M1 Closed magnetic path M2 Open magnetic path R1 Reference line R2 Reference point

Claims (11)

A detecting portion having a core that is formed of a magnetic material having a hollow portion, and said core and magnetically coupled to the coil,
A first plate and a second plate arranged to sandwich the detection unit from both sides in a predetermined detection direction;
An elastic body that is formed of a material having a lower elastic modulus than the core and that positions between the first plate and the second plate;
The detection unit is configured to receive a load applied from the first plate and the second plate in a direction along the detection direction ,
In the core, a magnetic path through which the magnetic flux generated by the current flowing through the coil passes is formed along the circumferential direction of the hollow portion,
The elastic body is sandwiched from both sides of the detection direction by the first plate and the second plate by adhering to the outer peripheral edge of the first plate and the outer peripheral edge of the second plate, A force sensor provided between the first plate and the second plate . A plurality of the detection units are provided,
The force sensor according to claim 1, wherein the plurality of detection units are arranged along a plane orthogonal to the detection direction.   The force sensor according to claim 2, wherein the plurality of detection units are arranged in line symmetry with respect to a reference line in the plane or point symmetry with respect to a reference point in the plane. Each of the first plate and the second plate has a through hole penetrating in the detection direction,
The force sensor according to claim 2, wherein the plurality of detection units are arranged around the through hole.   The plurality of detection units are arranged in a one-to-one correspondence with two or more detection positions selected from among a plurality of detection positions. Force sensor.   The force sensor according to any one of claims 2 to 5, wherein the cores of each of the plurality of detection units have the same size in the detection direction.   The force sensor according to any one of claims 1 to 6, further comprising a structure that is disposed between the first plate and the second plate and positions the detection unit. The structure has a positioning hole penetrating in the detection direction,
The force sensor according to claim 7, wherein the core is disposed inside the positioning hole.   9. The force sensor according to claim 7, wherein the structure is a substrate on which a circuit is formed.   An insulator is disposed between an outer shell including at least one of the first plate and the second plate and the substrate to electrically insulate the outer shell from the substrate. Item 10. The force sensor according to Item 9. 11. A force detection device 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.

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