JP2011043442A - Fluctuation load detection pad, fluctuation load detection plate using the same, distributed type fluctuation load detection plate, and fluctuation load detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thin fluctuation load detection pad capable of detecting a large fluctuation load, fluctuation load detection plate using the same, distributed type fluctuation load detection plate, and a fluctuation load detector. <P>SOLUTION: The fluctuation load detection pad 1 includes: a piezoelectric plate 11 formed from polymer piezoelectric material; a pair of electrode plates 12, 13 sandwiching the piezoelectric plate 11 therebetween; and a pair of insulation plates 14, 15 sandwiching the pair of electrode plates 12, 13 therebetween. Each of the pair of electrode plates 12, 13 comes into face contact directly with the piezoelectric plate 11 and is non-adhesive. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a variable load detection pad, a variable load detection plate using the same, a distributed variable load detection plate, and a variable load detection device.

  There is a demand for a technique for measuring and monitoring a fluctuating load as large as 1 kN (100 kg) to 1 MN (100 ton). Examples of the objects that require measurement of such a large variable load include, for example, a variable load on the base bottom of an outrigger in a crane vehicle, a variable load between a container of a container trailer and a vehicle, and a variable load between a track and a sleeper. , Fluctuating load of press machine, collision impact force of vehicle and the like.

  In the measurement of such a fluctuating load of a heavy object, a thin measuring device having a large pressure receiving area and capable of measuring a large fluctuating load is required. Further, depending on the situation, it is required to detect the displacement force in addition to the load applied by the object.

  As a thin pressure detection device having a large pressure receiving area, a variable load detection pad represented by Patent Document 1 is known. A piezoelectric film is used as an element for detecting pressure in the pressure detection device. The piezoelectric film changes the thickness of the film by pressing the film surface or expanding and contracting in the film surface direction. The acting load is detected by taking out the electric charge fluctuation generated in response through the electrode films arranged on both sides.

JP 2006-226858 A

  As disclosed in Patent Document 1 or the like, a material in which an electrode film such as a metal film by evaporation or sputtering or a conductive paste is formed on the surface of a piezoelectric plate is usually used. Since these electrode films are very thin and weak in strength, the electrode films are cracked or peeled off when a large load is applied. For this reason, it is difficult to use it for measuring a large fluctuating load.

  The present invention has been made in view of the above matters, and an object of the present invention is a variable load detection pad that is thin and capable of detecting a large variable load and a variable load detection plate using the same. Another object of the present invention is to provide a distributed variable load detection plate and a variable load detection device.

The variable load detection pad according to the present invention is:
A piezoelectric plate formed from a polymeric piezoelectric material;
A pair of electrode plates sandwiching the piezoelectric plate;
A pair of insulating plates sandwiching the pair of electrode plates,
Each of the pair of electrode plates is in direct surface contact with the piezoelectric plate, and is non-adherent.
The thickness of the piezoelectric plate is changed according to a load applied, and a voltage corresponding to the load is output from the piezoelectric plate.

  Further, it is desirable that at least one of the pair of electrode plates is smaller than the area of the piezoelectric plate.

  The electrode plate is preferably a metal plate.

  The metal plate is preferably a corrosion-resistant metal plate or a metal plate having a surface subjected to rust prevention treatment.

  The insulating plate may be made of a hard resin material.

  The insulating plate may be made of an elastic material that distributes the load to the pair of electrode plates.

Fluctuating load detection plate according to the present invention,
Any of the above fluctuating load detection pads;
A pair of pressure plates sandwiching the variable load detection pad;
A fixing member that presses the pair of pressure-receiving plates together to be fixed integrally with the fluctuating load detection pad.

Further, it is fixed by the fixing member so that a predetermined load is applied to the piezoelectric plate,
You may comprise so that the thickness change of the said piezoelectric plate may be produced according to the load exceeding the said predetermined load.

  The distributed variable load detection plate according to the first aspect of the present invention is characterized in that a plurality of any of the above variable load detection pads are arranged on the same plane.

  A distributed variable load detection plate according to a second aspect of the present invention is characterized in that a plurality of any of the above variable load detection plates are arranged on the same plane.

The variable load detection device according to the present invention is:
A pressure-receiving member having a U-shaped cross section having a pressure-receiving surface and a drooping portion formed with a recess;
A pair of the above-described fluctuating load detection plates disposed opposite to the hanging inner wall;
A support member that includes a displacement force transmission portion that contacts the pair of fluctuating load detection plates, and wherein the displacement force transmission portion is included in the recess of the pressure receiving member;
An elastic plate disposed between the pressure receiving member and the support member,
A displacement force generated along the pressure-receiving surface due to a load applied to the pressure-receiving member is transmitted to the displacement force transmission unit,
One of the pair of fluctuating load detection plates is pressed by the displacement force transmission unit,
The displacement force is detected from a difference between voltages output from the pair of fluctuating load detection plates.

  In addition, two sets of the pair of variable load detection plates are arranged opposite to each other so that a line connecting the one set of variable load detection plates and a line connecting the other set of the variable load detection plates intersect in a cross shape. It may be configured.

Further, the concave portion is disk-shaped, and a plurality of pairs of the variable load detection plates are respectively arranged to face the peripheral wall of the concave portion,
The support member may include the disc-shaped displacement force transmission unit that contacts a plurality of pairs of the fluctuating load detection plates.

  Furthermore, any one of the above-described fluctuating load detection pads may be disposed on the bottom surface of the support member, and the fluctuating load applied to the pressure receiving member may be detected.

  The fluctuating load detection pad according to the present invention has a form in which a piezoelectric plate is sandwiched between a pair of electrode plates having mechanical strength. The piezoelectric plate and the electrode plate are in direct surface contact and are not bonded.

  Since the electrode plate has mechanical strength, even if a large load is applied, the electrode plate is hardly cracked and can be used for measuring a large fluctuating load.

  Further, since the electrode plate and the piezoelectric plate are not bonded, there is no adhesive layer between the electrode plate and the piezoelectric plate, and no capacitance is generated. In addition, there is no elongation in the surface direction of the electrode plate due to the Poisson effect. For this reason, since the piezoelectric plate sandwiched between the electrode plates is compressed in the thickness direction in accordance with the load applied without being stretched along the surface, there is an advantage that the variable load can be detected with high accuracy.

  Furthermore, since each is composed of a thin piezoelectric plate, electrode plate, and insulating plate, it can be thin and can have a large pressure receiving area, and can be adapted to various uses.

1 is an external perspective view of a fluctuating load detection pad according to Embodiment 1. FIG. 4 is a plan perspective view of the variable load detection pad according to Embodiment 1. FIG. It is A-A 'sectional drawing of FIG. FIG. 3 is a B-B ′ sectional view of FIG. 2. (A) is sectional drawing of the piezoelectric plate in which the electrode film was formed, (B) is sectional drawing of the state to which the compressive load was added. It is a figure explaining the influence by the bending deformation of an electrode plate. It is sectional drawing which shows the use condition of the variable load detection pad in a location with an unevenness | corrugation. 6 is a cross-sectional view of a fluctuating load detection plate according to Embodiment 2. FIG. 10 is an external perspective view of a distributed variable load detection plate according to Embodiment 3. FIG. FIG. 10 is an external perspective view of a fluctuating load detection device according to a fourth embodiment. It is A-A 'sectional drawing of FIG. FIG. 6 is a partial cross-sectional view of a fluctuating load detection device according to a fourth embodiment. 6 is a plan view of a support member of a fluctuating load detection device according to Embodiment 4. FIG. (A) is an external perspective view of the fluctuating load detection device according to the fifth embodiment, (B) is an A-A ′ sectional view, and (C) is a B-B ′ sectional view. FIG. 10 is an external perspective view of a fluctuating load detection device according to a sixth embodiment. FIG. 10 is an external perspective view of a support member of a variable load detection device according to a sixth embodiment. It is A-A 'sectional drawing of FIG. FIG. 10 is a cross-sectional view of a fluctuating load detection device according to a seventh embodiment. FIG. 10 is a cross-sectional view of a fluctuating load detection device according to an eighth embodiment. It is a figure which shows the relationship between the load in Example 1, and the output of a fluctuation | variation load detection pad. It is a figure which shows the relationship between the load in Example 2, and the output of a fluctuation | variation load detection pad. It is a figure which shows the relationship between the load in Example 3, and the output of a fluctuation | variation load detection pad. It is a figure which shows the relationship between the load in Example 4, and the output of a fluctuation | variation load detection apparatus.

(Embodiment 1)
As shown in the external perspective view of FIG. 1, the perspective plan view of FIG. 2, and the cross-sectional views of FIGS. The pair of electrode plates 12 and 13 sandwiching the electrode plate, the pair of insulating plates 14 and 15 sandwiching the electrode plates 12 and 13, and the piezoelectric plate 11, the electrode plates 12 and 13, and the insulating plates 14 and 15 through the spacer 16 are integrated. It is comprised from the adhesive member 17 fixed to.

  The piezoelectric plate 11 is a film-like thin film, and is formed from a polymer piezoelectric material having flexibility. Examples of specific materials for the piezoelectric plate 11 include polyvinylidene fluoride and vinylidene cyanide. For the piezoelectric plate 11, for example, a commercially available polyvinylidene fluoride having a thickness of 20 μm to 200 μm and an elastic modulus of about 3000 MPa may be cut into a predetermined shape and used.

  The piezoelectric plate 11 made of a polymer piezoelectric material changes the thickness of the piezoelectric plate 11 when the plate surface is pressed, and the electric charge varies according to the change in thickness. The load acting on the variable load detection pad 1 can be measured by detecting this charge fluctuation, that is, the voltage via the electrode plates 12 and 13 arranged on both sides.

  The electrode plates 12 and 13 are arranged so as to sandwich the piezoelectric plate 11. The respective electrode plates 12 and 13 are in direct surface contact with the piezoelectric plate 11 and are not bonded to the piezoelectric plate 11. The electrode plates 12 and 13 are provided with terminal portions 18 and 19 for connecting electrical wiring (not shown) for outputting a charge signal generated by the piezoelectric plate 11. In the method in which the electrode film is formed on the piezoelectric plate 11 by vapor deposition, sputtering, conductive paste, or the like and the wiring is connected to the electrode film, the electrode film is thin, so that the wiring connection method is limited. Since is a metal plate, wiring can be easily connected to the terminal portions 18 and 19 by various methods such as soldering, caulking, and screwing.

  For the electrode plates 12 and 13, a thin metal plate having strength in the plane and having some flexibility outside the plane is used.

  Since the electrode plates 12 and 13 are disposed in direct contact with the piezoelectric plate 11, they are corrosion-resistant metal plates such as stainless steel, aluminum, and copper, which do not easily rust on the contact surface even when used for a long time. It is preferable. Alternatively, the electrode plates 12 and 13 may be metal plates on which at least a surface in contact with the piezoelectric plate 11 is subjected to rust prevention treatment such as noble metal plating (gold plating, silver plating, etc.) in order to suppress the generation of rust.

  At least one of the electrode plates 12 and 13 may be configured to be smaller than the area of the piezoelectric plate 11. If both the electrode plates 12 and 13 are larger than the size of the piezoelectric plate 11, the electrode plates 12 and 13 come into contact with each other at the portion protruding from the piezoelectric plate 11, and there is a possibility that the charge signal generated from the piezoelectric plate 11 cannot be measured. Because.

  Since the electrode plates 12 and 13 are in direct contact with the surface of the piezoelectric plate 11 and a strong pressure acts on the boundary surface with the piezoelectric plate 11, the surfaces of the electrode plates 12 and 13 in contact with the piezoelectric plate 11 are smooth. It is good to use what was processed into the plane. The degree of smoothness may be as smooth as a polishing finish (precision finish) that does not damage the piezoelectric plate 11.

  The insulating plates 14 and 15 have an effect of electrically insulating between the electrode plates 12 and 13 and an object to which a compressive force is applied. Since a large pressure is also applied to the insulating plates 14 and 15 due to the load of the object, the insulating plates 14 and 15 are made of a material having high electrical insulation and a high elastic modulus. As the insulating plates 14 and 15, a hard resin such as a resin sheet, a resin plate, or a fiber reinforced resin sheet is used. Specific examples include polyethylene terephthalate resin, nylon resin, hard vinyl chloride, and bakelite.

  The insulating plate 14 and the electrode plate 12, and the insulating plate 15 and the electrode plate 13 are bonded to each other by an adhesive member 17. Further, the edges of the insulating plate 14 and the insulating plate 15 are bonded to each other by the adhesive member 17 through the spacer 16 over the entire edge of the insulating plates 14 and 15. In this way, the piezoelectric plate 11, the electrode plates 12 and 13, and the insulating plates 14 and 15 are integrally fixed, and the variable load detection pad 1 is formed.

  As the bonding member 17, various materials that can bond the insulating plate 14 and the insulating plate 15, such as an adhesive or an adhesive material, are used. When the piezoelectric plate 11 and the electrode plates 12 and 13 are laminated and the thickness thereof is large, they may be bonded with a spacer 16 interposed therebetween as necessary.

  Further, when the size (area) of the piezoelectric plate 11 is small, the piezoelectric plate 11, the electrode plates 12, 13, and the insulating plate 14 can be obtained by simply bonding the edges of the insulating plates 14 and 15 via the adhesive member 17. , 15 can be fixed integrally, but when the size of the piezoelectric plate 11 is large, the following configuration is preferable.

  As shown in the perspective view of FIG. 2 and the cross-sectional view of FIG. 4, the piezoelectric plate 11 and the electrode plates 12 and 13 are provided with one or a plurality of corresponding openings, and the openings are also interposed via spacers 16. The insulating plates 14 and 15 are bonded together. In FIG. 2, two circular openings are provided in the piezoelectric plate 11 and the electrode plates 12 and 13.

  By configuring as described above, even if the piezoelectric plate 11 and the electrode plates 12 and 13 are not bonded, the mutual displacement between the piezoelectric plate 11 and the electrode plates 12 and 13 can be prevented.

  In the variable load detection pad 1 configured as described above, when a compressive load is received in the thickness direction of the variable load detection pad 1, the piezoelectric plate 11 is compressed according to the compressive load and generates a charge corresponding to the amount of compression. . Then, by taking out this electric charge through the electrode plates 12 and 13 and the terminal portions 18 and 19, the fluctuation load applied to the fluctuation load detection pad 1 can be detected with high accuracy.

  Here, the reason why the metal plates are used as the electrode plates 12 and 13 and the reason why the electrode plates 12 and 13 and the piezoelectric plate 11 are not bonded in the variable load detection pad 1 according to the present embodiment will be described.

  First, the reason why metal plates are used as the electrode plates 12 and 13 will be described.

  As described above, conventionally, an extremely thin electrode film such as vapor deposition or sputtering is formed on both surfaces of the piezoelectric plate 11. However, since this electrode film has low strength, if a large fluctuating load acts, The electrode film is peeled off. For this reason, a large fluctuating load cannot be detected.

  On the other hand, since the variable load detection pad 1 according to the present embodiment uses the electrode plates 12 and 13 made of a metal plate, the strength is high even if a large compressive force acts on the variable load detection pad 1. The electrode plates 12 and 13 are not easily damaged. Therefore, the fluctuating load detection pad 1 can sufficiently withstand a large fluctuating load to be applied, and can detect a large fluctuating load.

  Furthermore, another reason for using metal plates for the electrode plates 12 and 13 will be described with reference to FIG.

  FIG. 5A shows a variable load detection pad when thin electrode films 20 and 21 are formed on both surfaces of the piezoelectric plate 11 by conventional vapor deposition or sputtering and elastic layers 22 and 23 are provided on the electrode films 20 and 21. FIG. 5B schematically shows a cross-sectional view of a state in which a compressive force is applied to the variable load detection pad 51 through the rigid plates 24 and 25. .

  As indicated by arrows, when a compressive force is applied to the variable load detection pad 51 in the thickness direction, the piezoelectric plate 11 contracts in the thickness direction as shown in FIG. 5B, and at the same time, due to the Poisson effect of the piezoelectric plate 11 itself. A deformation that extends along the surface (perpendicular to the compressive force). When the compressive force is applied, the elastic layers 22 and 23 are also contracted in the thickness direction, and at the same time, the elastic layers 22 and 23 are deformed to extend along the surface (perpendicular to the compressive force) by the Poisson effect. The elongation of the elastic layers 22 and 23 increases as the elastic modulus of the elastic layers 22 and 23 decreases, and increases as the thickness of the elastic layers 22 and 23 increases.

  When the electrode films 20 and 21 are formed by vapor deposition, sputtering, or the like, the electrode films 20 and 21 do not strongly resist the elongation of the elastic layers 22 and 23. Therefore, the elastic layers 22 and 23 are stretched, The piezoelectric plate 11 is also stretched. Accordingly, the piezoelectric plate 11 is contracted in the thickness direction due to the expansion of the piezoelectric plate 11 by the elastic layers 22 and 23 in addition to being contracted in the thickness direction upon receiving a compressive load.

  While the compressive force acts on the entire surface of the piezoelectric plate 11, the force by which the elastic layers 22 and 23 stretch the piezoelectric plate 11 in the horizontal direction acts on the cut surface of the thin piezoelectric plate 11. For this reason, the thickness change of the piezoelectric plate 11 caused by the elastic layers 22 and 23 stretching the piezoelectric plate 11 is an amount that cannot be ignored with respect to the thickness change due to the compressive load. For this reason, in addition to the charge fluctuation due to the compressive strain, the charge fluctuation due to a non-negligible amount of stretching strain occurs from the piezoelectric plate 11. Therefore, the applied compressive load and the charge fluctuation from the piezoelectric plate 11 are not proportional, and the compressive load cannot be detected with high accuracy.

For example, polyethylene terephthalate resin sheets (0.2 mm, 0.7 mm, 1.2 mm) having different thicknesses on both sides of a 100 mm square piezoelectric film (80 μm thick) with aluminum vapor-deposited electrode films on both sides of the piezoelectric body. 2mm and 1.7mm) are each bonded with a rubber adhesive, and this is placed on the compression plate of the hydraulic servo tester, and a 60 x 60mm square metal pressure plate is placed on the upper surface to repeatedly compress the compression force. Table 1 shows the sensor output when 2.5 tons are loaded. The configuration of the measuring device is the same as that described in Example 1 described later. It can be seen from Table 1 that when the electrode film is thin, the output of the piezoelectric body varies depending on the thickness of the elastic layers 22 and 23, and the output increases as the elastic layer becomes thicker.

  On the other hand, the variable load detection pad 1 according to the present embodiment is a metal plate in which the electrode plates 12 and 13 have strength. Therefore, the electrode plates 12 and 13 are not stretched even if the compressive force applied to the variable load detection pad 1 causes the elastic layers 22 and 23 to extend in the horizontal direction due to the Poisson effect. For example, when the electrode plates 12 and 13 are stainless steel thin plates, the electrode plates 12 and 13 are not affected by the thickness and elastic modulus of the elastic layers 22 and 23 as long as the thickness is 0.1 mm or more. Accordingly, since the electrode plates 12 and 13 are not stretched, the piezoelectric plate 11 sandwiched between the electrode plates 12 and 13 is not stretched.

  In addition, when the electrode film is an extremely thin electrode film such as vapor deposition or sputtering, the elastic layer extends the piezoelectric plate in the horizontal direction to some extent outside the area where the compressive force is applied. For this reason, the output of the piezoelectric plate is affected by the load area. In other words, even if the same force is applied, the charge fluctuation from the piezoelectric plate differs depending on the area where the force is applied, making it difficult to measure with high accuracy.

  On the other hand, when the variable load detection pad 1 of the present invention receives a compressive force, the electrode plates 12 and 13 restrain the elongation along the surface of the piezoelectric plate 11 by contact friction. That is, only the thickness change due to the compressive force occurs in the piezoelectric plate 11. For this reason, the load according to the compressive force is generated almost without being affected by the load area, so that the fluctuating load can be accurately detected.

  As described above, in the variable load detection pad 1 of the present invention, the metal plate is used as the electrode plates 12 and 13, so that the compression force and the output from the piezoelectric plate 11 can be obtained even if the pad size is small or large. Further, there is an advantage that the output of the piezoelectric plate 11 is hardly affected by the load area.

  Next, the reason why the electrode plates 12 and 13 and the piezoelectric plate 11 are not bonded in the variable load detection pad 1 according to the present embodiment will be described.

  When the electrode plates 12 and 13 and the piezoelectric plate 11 are bonded, an adhesive layer made of an adhesive member or an adhesive member is formed between the electrode plates 12 and 13 and the piezoelectric plate 11. As a result, capacitance is generated between the electrode plates 12 and 13 and the piezoelectric plate 11, and the output signal of the piezoelectric plate 11 is significantly reduced.

  In addition, when the electrode plates 12 and 13 are bonded to the surface of the piezoelectric plate 11, the thickness of the adhesive layer interposed between the electrode plates 12 and 13 and the piezoelectric plate 11 changes when a large compressive force is applied. Arise. When the thickness of the adhesive layer changes, the capacitance formed by the surfaces of the electrode plates 12 and 13 and the piezoelectric plate 11 changes, and the detection accuracy decreases.

  On the other hand, in the fluctuating load detection pad 1 according to the present embodiment, the electrode plates 12 and 13 and the surface of the piezoelectric plate 11 are in the non-bonded state. Becomes zero and no capacitance is generated, so that highly accurate measurement can be realized.

  Moreover, the electrode plates 12 and 13 are good to be comprised from the thin metal thin plate. When thick metal plates are used as the electrode plates 12 and 13, the variable load detection pad 1 may be bent out of plane due to a compressive force during use. For example, as shown in FIG. 6, it is assumed that a compressive force is received and the electrode plates 12 and 13 are bent and deformed downward toward the bottom of the drawing sheet. At this time, since the electrode plates 12 and 13 are metal plates having a large elastic modulus, the upper and lower electrode plates 12 and 13 bend around the respective neutral axes shown by the one-dot chain line in FIG. Then, the surface of the upper electrode plate 12 in contact with the piezoelectric plate 11 on the paper surface is distorted by bending deformation. Further, the surface of the lower electrode plate 13 that comes into contact with the piezoelectric plate 11 is distorted by bending deformation. Then, due to the frictional force between the electrode plates 12 and 13 and the piezoelectric plate 11, the upper surface of the piezoelectric plate 11 is strained to expand, and the lower surface of the piezoelectric plate 11 is strained to contract. As a result, the piezoelectric plate 11 generates an output due to bending deformation.

  On the other hand, if the electrode plates 12 and 13 are thin metal plates, even if the electrode plates 12 and 13 are bent and deformed, there is little change in bending distortion on the surfaces of the electrode plates 12 and 13, and the variable load detection pad 1 is used. Even when it is bent out of the plane, highly accurate measurement is possible.

Next, the load bearing capacity of the variable load detection pad 1 will be described. In the variable load detection pad 1, the pressure acting on the piezoelectric plate 11 is transmitted through the insulating plates 14 and 15 and the electrode plates 12 and 13. For example, when the surface of the electrode plate 12 having a smaller area is a square having a side of 50 mm and a compressive load of 100 kN (10 ton) is applied to the center of both surfaces of the variable load detection pad 1, the pressure applied to the piezoelectric plate 11 Is 40 MPa (σ = 100,000 (N) / (50 × 50) mm ² = 40). For example, when the thickness of the piezoelectric plate 11 is 0.1 mm, the amount of contraction of the thickness of the piezoelectric plate 11 caused by the pressure of 40 MPa is about 0.0013 mm ((δ = σ × h / E = 40 (MPa) × 0 0.1 (mm) / 3000 (MPa)), which is about 1.3% of the thickness of the piezoelectric plate 11. This change in thickness is in the range of the load bearing capacity of the piezoelectric plate 11. That is, a 50 mm square pressure plate A compressive force of 10 tons can be measured with the dimension variable load detection pad 1.

Next, in addition to the amount of contraction of the piezoelectric plate 11, the overall rigidity of the variable load detection pad 1 is assumed to be such that the electrode plates 12 and 13 are both a stainless steel plate having a thickness of 0.1 mm and a pair of insulating plates 14 and 15. Table 2 shows the results of a rough calculation for the case where both are resin plates having a thickness of 0.2 mm and an elastic modulus E = 2500 MPa.

  In the table, the total thickness of the fluctuating load detection pad 1 is 0.7 mm. When the compressive force of 100 kN (10 ton) is applied to the fluctuating load detection pad 1, the total amount of shrinkage of the entire thickness is as small as 0.0078 mm. Thus, the variable load detection pad 1 according to the present embodiment has a configuration that is rigid with respect to a large compressive force.

  In the above, the insulating plates 14 and 15 using the hard resin sheet have been described. However, the insulating plates 14 and 15 are made of an elastic material that also functions as a cushion member that distributes a compressive load to the electrode plates 12 and 13. Also good. As the insulating plates 14 and 15, for example, a low elastic modulus material such as natural rubber, synthetic rubber, or cloth-drawn rubber may be used.

  When an elastic material is used as the insulating plates 14 and 15, it is effective when measuring the compressive force of an object by installing it on a heavy object such as a trailer carriage surface or concrete ground. In such a case, sand particles are attached to the surface of a support member such as a truck or concrete on which the variable load detection pad 1 is to be placed, welding spatter is attached, or it is locally bent. It may not be flat.

  In FIG. 7, the cross section at the time of using the variable load detection pad 1 in the location where the sand grain 28 has adhered to the surface of the target object 26 which applies compressive force, and the surface of the mounting base 27 is shown typically. The insulating plates 14 and 15 having a low elastic modulus such as rubber plates absorb the influence of unevenness caused by the sand particles 28 on the surface of the object 26 and the mounting table 27, and gently transmit the compressive force to the electrode plates 12 and 13. It becomes like this.

  In the variable load detection pad 1, the piezoelectric plate 11 is made of a flexible polymer material, and the electrode plates 12 and 13 have strength and can be bent out of plane. Since it is a metal thin plate, the piezoelectric plate 11 and the electrode plates 12 and 13 can bend and deform according to the pressure distribution.

  For this reason, even when there is unevenness in the place where the load is placed, such as sand particles adhering to the cart or concrete on which the load changing pad 1 is to be placed, the load changing can be measured with high accuracy.

  In addition, since the variable load detection pad 1 is arranged over substantially the entire surface of the variable load detection pad 1 except for the spacer 16 portion, the variable load detection pad 1 having a large pressure receiving area is provided. Can be realized. Further, the shape of the pressure receiving surface can be freely manufactured and used in accordance with the application other than the rectangular shape.

(Embodiment 2)
Next, the variable load detection plate 2 for detecting the compressive force according to the second embodiment will be described with reference to the cross-sectional view of FIG.

  The variable load detection plate 2 has a configuration in which the above-described variable load detection pad 1 is sandwiched between a pair of pressure receiving plates 31 and 32 and these are integrated with a fixing member 33.

  As the fixing member 33, for example, a fixing tool that is tightened with a nut through a bolt in the opening provided in the above-described variable load detection pad 1 is used.

  The pressure receiving plates 31 and 32 are each formed of a metal having mechanical strength.

  The diameter of the opening of the variable load detection pad 1 is made slightly larger than the bolt diameter, and is tightened with bolts and nuts. The two pressure receiving plates 31, 32 are pressed against each other so as to compress the variable load detection pad 1. Become. By fixing in this way, a predetermined load is applied to the piezoelectric plate 11 disposed in the variable load detection pad 1, that is, the piezoelectric plate 11 is compressed by a predetermined thickness. .

  In this way, the variable load detecting plate 2 causes a thickness change without resistance to a compressive force exceeding a predetermined compressive force, that is, the thickness change of the piezoelectric plate 11 according to the compressive force exceeding the predetermined compressive force. Can be generated.

  Further, when the size of the variable load detection pad 1 is arranged over most of the size of the variable load detection plate 2, the variable load detection plate 2 which is thin, has a large pressure receiving area and high strength can be configured. .

  The fixing member 33 is preferably in an embedded state in which the bolt head and nut do not protrude from the pressure receiving plates 31 and 32. The variable load detection plate 2 is used by placing it on a mounting table or the like, or by fixing one surface with an adhesive sheet, or by making one of the pressure receiving plates 31 and 32 large and screwing it. It can be used by being fixed to a wall or the like. The gap around the pressure receiving plates 31 and 32 may be sealed with a rubber adhesive or the like.

(Embodiment 3)
Next, the distributed variable load detection plate 3 according to Embodiment 3 will be described with reference to FIG. As shown in the external perspective view of FIG. 9, the distributed variable load detection plate 3 has a configuration in which a plurality of the above-described variable load detection pads 1 are arranged on the same plane. Thus, by arranging the variable load detection pad 1, it is possible to easily detect how much load is applied to which part.

  The variable load detection pads 1 may be all the same size. Further, the variable load detection pad 1 may be disposed with its end faces adhered, or each variable load detection pad 1 may be disposed on a rigid plate or the like. In FIG. 9, the fluctuating load detection pad 1 is two-dimensionally arranged, but may be arranged one-dimensionally and may be appropriately arranged according to the intended use.

  Further, the fluctuating load detection plate 2 according to the second embodiment may be used, and similarly, two-dimensionally or one-dimensionally arranged on the same plane.

(Embodiment 4)
Next, a description will be given of a variable load detection device 4 that uses the above-described variable load detection plate 2 to detect a displacement force when a compressive load is applied.

  As shown in the external perspective view of FIG. 10 and the cross-sectional view of FIG. 11, the variable load detection device 4 according to Embodiment 4 mainly includes a pressure-receiving member 41 having a U-shaped cross-section having a pressure-receiving surface and a hanging part, It has a pair of fluctuating load detection plates 2a, 2a 'arranged opposite to the inner wall of the drooping portion, and displacement force transmitting portions 44a, 44a' that come into contact with the pair of fluctuating load detection plates 2a, 2a '. , 44 a ′ are comprised of a support member 43 enclosed in the pressure receiving member 41, and an elastic plate 42 disposed between the pressure receiving member 41 and the support member 43.

  The pressure receiving member 41 is a box having an opening on one side, and is made of a material such as metal having mechanical strength. A pair of fluctuating load detection plates 2a and 2a 'are disposed on the inner wall of the hanging portion of the pressure receiving member 41 so as to face each other. The fluctuating load detection plates 2a and 2a 'have the same configuration as that of the fluctuating load detection plate 2 described above, and a description thereof will be omitted. In the figure, the pressure receiving member 41 is described as a box. However, when detecting a uniaxial displacement force, the plate-like member may be bent in a U-shaped cross section. Good.

  The support member 43 is made of a material having high mechanical strength such as metal. A part of the support member 43 is included in a U-shaped pressure receiving member 41, and an elastic plate 42 is disposed between the support member 43 and the back surface of the pressure receiving surface of the pressure receiving member 41. The support member 43 may be fixed to the base 46 or the like. The base 46 may be provided with a hole 45 that is fixed to a wall or a mounting table with screws or the like.

  Displacement force transmitting portions 44 a and 44 a ′ are formed on the side surface of the support member 43 facing the hanging portion of the pressure receiving member 41. The displacement force transmitting portions 44a and 44a ′ project in an arc shape toward the variable load detection plates 2a and 2a ′ arranged at the hanging portion of the pressure receiving member 41, and the respective displacement force transmission portions 44a and 44a ′ It is in contact with the detection plates 2a and 2a ′.

  The arcuate portions at both ends of the displacement force transmitting portions 44a and 44a 'are processed into an arc shape with the center of the width of the displacement force transmitting portions 44a and 44a' and the contact portion as a radius. Although not shown, the hanging parts at both ends of the pressure receiving member 41 are provided with adjusting screws or the like for pressing the fluctuating load detecting plates 2a and 2a 'against the displacement force transmitting portions 44a and 44a'. ing.

  The elastic plate 42 has a characteristic of transmitting a compressive force of the bottom surface of the pressure receiving member 41 to the support member 43 and not transmitting a displacement force. In other words, the displacement force received by the pressure receiving member 41 is transmitted from the pair of fluctuating load detection plates 2a and 2a ′ fixed to the hanging portion to the support member 43 via the displacement force transmitting portions 44a and 44a ′. is there. The elastic plate 42 may be a rubber plate, a hard rubber plate, or a low elastic modulus plate such as soft vinyl chloride or a fluororesin plate.

  When the elastic plate 42 receives a compressive force, it contracts greatly in the thickness direction from the original state shown by the broken line in FIG. When formed, the elastic plate 42 may be formed in a shape that substantially matches the size of the upper surface of the support member 43 in a state where a compressive force is applied, as shown in the plan view of FIG. As shown in FIG. 13, by forming the elastic plate 42 with each side curved inward, when a compressive force is applied, the elastic plate 42 is deformed into a shape indicated by a broken line.

  Next, the principle of detecting the displacement force of the variable load detection device 4 will be described. When a displacement force simultaneously acts on the surface of the pressure receiving member 41, the elastic plate 42 contracts in the thickness direction due to the compression force. Further, when the compressive force acts at a position shifted from the center of the pressure receiving member 41, the pressure receiving member 41 slightly rotates.

  In addition, the elastic plate 42 feels as if a part of the displacement force is transmitted to the support member 43 by the frictional force. However, actually, even if the elastic plate 42 is sheared and deformed by the displacement force, the displacement force transmitting portion 44a. 44a ', the arc portions at both ends are in contact with the variable load detection plates 2a, 2a' and the variable load detection plates 2a, 2a 'are hard in the thickness direction, so that the pressure receiving member 41 is the variable load detection plate. Even if the displacement force transmitting portions 44a and 44a ′ are pushed through 2a and 2a ′, the pressure receiving member 41 can hardly be displaced in the direction of the displacement force.

  That is, since the elastic plate 42 has a small elastic modulus, the elastic plate 42 is easily sheared and deformed by the displacement force, but the displacement force transmitting portions 44 a and 44 a ′ stop the displacement of the pressure receiving member 41. For this reason, the elastic plate 42 is not shear-deformed and transmits almost no displacement force.

  For this reason, almost all of the displacement force is transmitted to the pair of variable load detection plates 2a, 2a ′, so that the pair of variable load detection plates 2a, 2a ′, that is, the respective variable load detection plates 2a, The displacement force can be measured by taking out the output from the piezoelectric plate 11 arranged in 2a 'and measuring the difference.

  As described above, the variable load detection plate 4 for detecting the displacement force according to the present embodiment has a structure in which the compressive force is received by the elastic plate 42 without floating the strain-generating portion in the air. The variable load detection plate 4 having a large area and high strength can be provided.

  The shift force detection plate 2a, 2a ′ needs to be hard in the thickness direction according to the principle of detecting the displacement force according to the present embodiment. However, if it is hard in the thickness direction, the conventional ceramics or the like can be used. Even a piezoelectric body can be applied.

(Embodiment 5)
Moreover, although the form which detects the deviation | shift force of a uniaxial direction was demonstrated above, it can also be set as the form which detects the deviation | shift force of a biaxial direction. For example, the following configuration may be used.

  14A is an external perspective view of the fluctuating load detection device 5 according to Embodiment 5, and FIGS. 14B and 14C are cross-sectional views taken along line AA ′ of FIG. It is BB 'sectional drawing. The pressure receiving member 41 is a box provided with hanging portions in two directions of the X axis direction and the Y axis direction orthogonal to the X axis direction. As shown in FIG. 14 (B), the variable load detection plates 2a, 2a 'are arranged on the inner walls of the hanging parts facing the X-axis direction of the pressure receiving member 41, and as shown in FIG. 14 (C). In addition, the variable load detection plates 2b and 2b ′ are arranged on the inner walls of the drooping portions facing each other in the Y-axis direction. Accordingly, the displacement force transmitting portions 44a and 44a ′ formed by projecting in the X-axis direction of the support member 43 are disposed so as to contact the variable load detection plates 2a and 2a ′, respectively. Displacement force transmitting portions 44b and 44b ′ formed so as to protrude in the direction are arranged so as to abut against the variable load detection plates 2b and 2b ′, respectively.

  With this configuration, the pressure receiving member 41 receives the pressure by detecting the difference between the output voltages from the fluctuating load detection plates 2a and 2a 'and the difference between the output voltages from the fluctuating load detection plates 2b and 2b'. The displacement force in the X-axis and Y-axis directions acting on the surface can be detected.

(Embodiment 6)
Furthermore, it can also be set as the form which detects the shift | offset | difference force of a several axis | shaft using the several pairs variable load detection board 2. FIG. In order to detect the displacement force of a plurality of axes, for example, the following configuration may be used.

  15 is an external perspective view of the fluctuating load detection device 6 according to Embodiment 6, FIG. 16 is an external perspective view of the support member 43, and FIG. 17 is a cross-sectional view taken along line A-A ′ of FIG.

  The pressure receiving member 41 is composed of a flat cylinder having a pressure receiving surface as a bottom surface, that is, a disk-shaped recess is formed inside. A support member 43 in which a displacement force transmitting portion 44 is formed is included in the disk-shaped recess formed in the pressure receiving member 41.

  The support member 43 fixed to the base 46 is a flat cylindrical body, and is formed with a displacement force transmitting portion 44 that protrudes outward in an arc shape over the entire circumference of the cylindrical body. An elastic plate 42 is disposed between the support member 43 and the back surface of the pressure receiving surface of the pressure receiving member 41.

  As shown in FIG. 17, a plurality of pairs of fluctuating load detection plates 2 a, 2 a ′, 2 b, 2 b ′, 2 c, 2 c ′ are formed on the peripheral wall of the concave portion of the pressure receiving member 41 with the center of the pressure receiving member 41 as the center point. 2d, 2d ′, 2e, 2e ′, 2f, 2f ′, 2g, 2g ′, 2h, and 2h ′ are arranged radially.

  With the above-described configuration, it is possible to detect a plurality of axial displacement forces acting on the pressure receiving surface of the pressure receiving member 41.

(Embodiment 7)
Next, the variable load detection device 7 according to Embodiment 7 will be described with reference to the cross-sectional view of FIG. The fluctuating load detection device 7 shows an example of another configuration of the fluctuating load detection device 4 described above.

  In this configuration, the width of the hanging portion of the pressure receiving member 41 is widened, and the widths of the displacement force transmitting portions 44 a and 44 a ′ of the support member 43 are reduced. The elastic plate 42 is provided at two positions on the left and right sides of the displacement force transmitting portions 44 a and 44 a ′ so as to transmit the compression force to the support member 43. In FIG. 18, the support member 43 is fixed to the object by a fixing member 47 such as a pin. However, the figure is reversed upside down and used with the support member 43 on the upper side and the pressure receiving member 41 on the lower side. May be. Moreover, you may comprise so that the displacement force of 2 axes may be detected similarly to the above.

(Embodiment 8)
Next, the variable load detection device 8 that detects both the compressive force acting in the direction perpendicular to the pressure receiving surface of the pressure receiving member 41 and the displacement force acting in the direction along the surface of the pressure receiving surface will be described with reference to FIG.

  The variable load detection device 8 has a configuration in which the variable load detection pad 1 described in the first embodiment is sandwiched between the support member 43 and the base 46 in the variable load detection device 4 described in the fourth embodiment. .

  For example, the variable load detection pad 1 is sandwiched between the support member 43 and the base 46, a predetermined pressure is applied, and the fixed member 48 such as a bolt and a nut is fixed, thereby exceeding the compressive force of the fixed member 48. The fluctuating load detection pad 1 can be fixed so as to cause a thickness change without resistance against the compressive force.

  With this configuration, both the compressive force acting on the pressure receiving surface of the pressure receiving member 41 and the displacement force can be detected simultaneously.

Example 1
An experiment was conducted on a variable load detection pad using a polyethylene terephthalate resin plate as an insulating plate. A stainless steel electrode plate with a thickness of 0.1 mm is arranged on both sides of a piezoelectric plate with a side of 80 mm square and a thickness of 80 μm so as to be in direct contact with the piezoelectric plate, and a polyethylene terephthalate with a thickness of 0.2 mm on both sides. A fluctuating load detection pad (hereinafter referred to as fluctuating load detection pad A1) was prepared by adhering a resin plate and fixing the edge portion.

  The variable load detection pad A1 was sandwiched between compression plates of a hydraulic servo fatigue tester having a capacity of 200 KN, and a compression force was applied at a repetition rate of 2 Hz.

  Electrical wiring is connected to the electrode plate, and an integration circuit is connected to the electrical wiring (capacitor 4.4 μF is connected in parallel), and the output of the integration circuit is a voltage recorder (input impedance 1ΜΩ, Omniace RA1300, NEC Sanei) And recorded simultaneously with the load waveform of the load cell of the hydraulic servo fatigue tester.

  FIG. 20 shows an example of the relationship between the fluctuation range of the compressive force recorded by the load cell of the testing machine and the fluctuation range of the output of the fluctuation load detection pad A1, and the output of the fluctuation load detection pad A1 is in a good proportional relationship with the load. I understand that.

  FIG. 20 also shows experimental results using a variable load detection pad A1 having a side of 20 mm square and 40 mm square and the same configuration, but it can be seen that the pad output is not affected by the pad size.

  Further, a maximum of 100 kN (about 10 ton) sinusoidal waveform was loaded 2000 times, but no change was observed in the output waveform of the variable load detection pad. Therefore, since the variable load detection pad A1 uses a metal plate as an electrode plate, it can be seen that the load resistance is large without being damaged.

(Example 2)
Subsequently, the durability when a piezoelectric film on which an aluminum vapor deposition electrode film was formed was verified.

  A variable load detection pad provided with an output amplification member in which a silicon rubber plate with a thickness of 0.5 mm is bonded with a rubber adhesive on both sides of a 100 mm square piezoelectric film (80 μm thickness) with an aluminum deposited electrode film (Hereinafter, this is referred to as a variable load detection pad B1). Similarly, a variable load detection pad (hereinafter referred to as a variable load detection pad B2) was prepared using a silicon rubber plate having a thickness of 1 mm. Further, a variable load detection pad (hereinafter referred to as a variable load detection pad A2) having the same configuration as that of Example 1 and having a piezoelectric plate dimension of 100 mm square on one side was created.

  These fluctuating load detection pads B1, B2, and A2 are placed on the compression plate of the hydraulic servo fatigue tester, respectively, and a metal pressure plate of 40 × 40 mm square, 60 × 60 mm square, or 100 × 100 mm square on the upper surface side. And repeatedly applied compressive force. The configuration of the measuring device is the same as that described in the first embodiment.

  The result is shown in FIG. In the variable load detection pads B1 and B2 formed with the aluminum vapor-deposited electrode film, as shown by x, when loaded with a 40 × 40 mm square pressure plate, the electrodes are loaded with a load of about 0.7 tons and 2.0 tons, respectively. The film was cracked and no further load could be measured. On the other hand, it can be seen that the variable load detection pad A2 using the metal plate as the electrode plate can be measured without being damaged even if the load exceeds that.

  Further, the outputs of the variable load detection pads B1 and B2 vary depending on the load load area by the silicon rubber plate, and the sensor output is larger when the load load area is smaller, and a constant output is not generated. On the other hand, the variable load detection pad A2 uses a metal plate that is difficult to extend in the surface direction as an electrode plate, and therefore is not affected by the load load area due to the difference in the area of the pressure plate, and both generate a constant output. I understand that.

(Example 3)
An experiment was conducted on a variable load detection pad using a silicon rubber plate as an insulating plate.

  A 0.1mm thick stainless steel plate is placed on both sides of an 80 micron thick piezoelectric film, and a 1mm thick silicon rubber plate with a rubber hardness of 70 is bonded to both outer sides. (Hereinafter referred to as a fluctuating load detection pad A3).

  Two 0.7 mm diameter wires are laid in parallel on the bottom surface of the variable load detection pad A3, and one 0.7 mm diameter wire is placed on the top surface of the variable load detection pad A3 so as to be substantially orthogonal to the bottom wire. Then, both sides were sandwiched between compression plates of a hydraulic servo fatigue tester, and compression force was applied repeatedly.

  Further, an aluminum plate having a thickness of 0.5 mm was placed in a staggered manner on the bottom and top surfaces of the variable load detection pad A3, and a compression force was repeatedly applied on the compression plate.

  The result is shown in FIG. Whether the wire is placed or an aluminum plate is placed, the variable load detection pad A3 shows that the applied load and the sensor output are proportional to each other with high accuracy, as in the case where no wire is placed.

Example 4
An experiment was performed using the fluctuating load detection apparatus described in the fourth embodiment.

  Since it is difficult to load a large displacement force in the laboratory, the support member of the fluctuating load detector is tilted on the horizontal bed of the hydraulic servo fatigue tester, and a push rod with a rounded tip is attached to the actuator. The upper surface of the pressure receiving plate was pushed at a repetition rate of 1 Hz. The inclination angle was 8.8 degrees, 14 degrees, 17.2 degrees, or 45 degrees.

  The waveform of the load cell of the testing machine and the output waveform of the sensor were recorded. The displacement force was obtained from the inclination angle θ between the bed of the test machine and the support member by multiplying the force W applied to the push rod by sin θ and the displacement force = W × sin θ.

  FIG. 23 shows the relationship between the displacement force and the output of the fluctuating load detection device. From the graph, it can be seen that the fluctuating load detection device shows a proportional relationship between the displacement force and the sensor output with high accuracy.

  As described above, the variable load detection pad according to the present invention is thin, has a large load resistance, and can detect a large variable load. Therefore, large loads such as fluctuating loads on the base bottom of outriggers in crane trucks, fluctuating loads between containers and vehicles on container trailers, fluctuating loads between tracks and sleepers, fluctuating loads on press machines, collision impact forces on vehicles, etc. It can be used when measuring.

DESCRIPTION OF SYMBOLS 1 Fluctuation load detection pad 2, 2a-2h, 2a'-2h 'Fluctuation load detection board 3 Distributed type fluctuation load detection board 4 Fluctuation load detection apparatus 5 Fluctuation load detection apparatus 6 Fluctuation load detection apparatus 7 Fluctuation load detection apparatus 8 Fluctuation load detection apparatus 8 Detection device 11 Piezoelectric plate 12 Electrode plate 13 Electrode plate 14 Insulating plate 15 Insulating plate 16 Spacer 17 Adhesive member 18 Terminal unit 19 Terminal unit 20 Electrode film 21 Electrode film 22 Elastic layer 23 Elastic layer 24 Rigid plate 25 Rigid plate 26 Object 27 Mounting table 28 Sand grain 31 Pressure receiving plate 32 Pressure receiving plate 33 Fixed member 41 Pressure receiving member 42 Elastic plate 43 Support member 44 Displacement force transmitting portion 44a, 44a ', 44b, 44b' Displacement force transmitting portion 45 hole 46 base 47 fixing member 48 fixing member 51 Fluctuating load detection pad

Claims (14)

A piezoelectric plate formed from a polymeric piezoelectric material;
A pair of electrode plates sandwiching the piezoelectric plate;
A pair of insulating plates sandwiching the pair of electrode plates,
Each of the pair of electrode plates is in direct surface contact with the piezoelectric plate, and is non-adherent.
A variable load detection pad, wherein the thickness of the piezoelectric plate is changed according to a load applied, and a voltage corresponding to the load is output from the piezoelectric plate.   The variable load detection pad according to claim 1, wherein at least one of the pair of electrode plates is smaller than an area of the piezoelectric plate.   The variable load detection pad according to claim 1, wherein the electrode plate is a metal plate.   The variable load detection pad according to claim 3, wherein the metal plate is a corrosion-resistant metal plate or a metal plate having a surface subjected to rust prevention treatment.   The variable load detection pad according to claim 1, wherein the insulating plate is made of a hard resin material.   The variable load detection pad according to claim 1, wherein the insulating plate is made of an elastic material that distributes the load to the pair of electrode plates. The variable load detection pad according to any one of claims 1 to 6,
A pair of pressure plates sandwiching the fluctuating load detection pad;
A variable load detection plate, comprising: a fixing member that presses the pair of pressure receiving plates together to be fixed integrally with the variable load detection pad. It is fixed by the fixing member so that a predetermined load is applied to the piezoelectric plate,
The fluctuation load detection plate according to claim 7, wherein a thickness change of the piezoelectric plate is caused in response to a load exceeding the predetermined load.   A distributed variable load detection plate, wherein a plurality of the variable load detection pads according to claim 1 are arranged on the same plane.   A distributed variable load detection plate, wherein a plurality of variable load detection plates according to claim 7 or 8 are arranged on the same plane. A pressure-receiving member having a U-shaped cross section having a pressure-receiving surface and a drooping portion formed with a recess;
A pair of fluctuating load detection plates according to claim 7 or 8, which are arranged to face the hanging wall.
A support member that includes a displacement force transmission portion that contacts the pair of fluctuating load detection plates, and wherein the displacement force transmission portion is included in the recess of the pressure receiving member;
An elastic plate disposed between the pressure receiving member and the support member,
A displacement force generated along the pressure-receiving surface due to a load applied to the pressure-receiving member is transmitted to the displacement force transmission unit,
One of the pair of fluctuating load detection plates is pressed by the displacement force transmission unit,
The variable load detection device, wherein the shift force is detected from a difference between voltages respectively output from the pair of variable load detection plates.   Two sets of the pair of variable load detection plates are arranged opposite to each other, and a line connecting the one set of variable load detection plates and a line connecting the other set of the variable load detection plates intersect in a cross shape. The fluctuating load detection device according to claim 11. The concave portion is disk-shaped, and a plurality of pairs of the fluctuating load detection plates are respectively opposed to the peripheral wall of the concave portion,
The variable load detection device according to claim 11, wherein the support member includes the disc-shaped displacement force transmission unit that abuts against a plurality of pairs of the variable load detection plates.   Furthermore, the variable load detection pad according to any one of claims 1 to 6 is arranged on the bottom surface of the support member, and the variable load applied to the pressure receiving member is detected. Detection device.

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