JP7295736B2 - Explosion proof mat switch - Google Patents

Description

TECHNICAL FIELD The present invention relates to a technique for an explosion-proof mat switch that satisfies explosion-proof standards.

Mat switches are widely used, for example, as human detection or crime prevention devices on production lines in chemical plants.

For example, Japanese Laid-Open Patent Publication No. 2002-100001 proposes a mat switch that incorporates a contact element in which an upper electrode and a lower electrode, which are partially insulated with a minute gap therebetween, face each other between an upper plate and a lower plate.

Utility Model Registration No. 3063415

In the invention described in Patent Document 1, the upper plate and the lower plate are made of urethane material. A urethane material is a kind of rubber having insulating properties. Since insulating rubber is easily electrified, a mat switch using insulating rubber may generate sparks due to static electricity. Further, in the invention described in Patent Document 1, there is a space between the upper plate and the lower plate, and since the plate is sandwiched between the upper plate and the lower plate, which tend to be charged, discharge may occur. Here, for example, it is conceivable to make the outside of the mat switch conductive by using conductive rubber for the upper plate and the lower plate, or by covering the upper plate with an antistatic conductive rubber, and grounding the ground. , the charge inside the mat switch cannot be removed. Therefore, considering that combustible gas enters inside the mat switch due to breakage or the like, the conventional mat switch is insufficient for safe use in an atmosphere of combustible gas.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide an explosion-proof mat switch that satisfies the standards for intrinsically safe explosion-proof construction.

The explosion-proof mat switch of the present invention comprises a conductive rubber upper plate, a conductive rubber lower plate facing the upper plate, a conductive rubber lower plate disposed between the upper plate and the lower plate, and a heavy weight. It is characterized by comprising a detection element for detecting a load and a connection member for electrically and physically connecting the upper plate and the lower plate.

In this configuration, the upper and lower plates are connected by connecting members. A connecting member physically secures the upper and lower plates. The upper plate and the lower plate are made of conductive rubber. Also, the upper plate and the lower plate have the same potential due to the connection member. As a result, the explosion-proof mat switch can eliminate potential imbalance between the upper plate and the lower plate. Therefore, the explosion-proof mat switch can prevent the generation of sparks simply by grounding either the upper plate, the lower plate, or the connecting member, so that it can sufficiently satisfy the standards for the intrinsically safe explosion-proof structure.

Also, an adhesive may be provided for bonding the upper plate and the lower plate to each other.

In this configuration, the top and bottom plates are glued together. Therefore, it is difficult for water, dust, etc. to enter between the upper plate and the lower plate. Therefore, the explosion-proof mat switch has improved water resistance and durability. Since the upper plate and the lower plate are electrically connected by the connection member, the same potential can be maintained even when they are adhered with an adhesive.

Also, a conductive rubber frame plate may be further provided between the upper plate and the lower plate.

In this configuration, since the frame plate is also made of conductive rubber, it has the same potential as the upper plate and the lower plate. The frame plate functions as a spacer between the upper plate and the lower plate. Therefore, the frame plate forms a space for arranging the detection element between the upper plate and the lower plate. Therefore, even if the upper plate and the lower plate are flat, it is possible to secure a space for arranging the detection element.

Also, the connecting member may include an insert nut.

A general purpose insert nut can be used in this configuration. The insert nut facilitates connection of the ground wire. Therefore, the explosion-proof mat switch can be easily grounded through the ground wire.

At least one of an inner peripheral female thread and an outer peripheral male thread may be formed in the connecting member.

With this configuration, when the inner circumference of the connection member is internally threaded, the user can easily connect the ground wire with the external thread. In addition, when a male screw is formed on the outer periphery of the connecting member, the male screw is firmly connected to the upper plate and the lower plate because the screw thread of the male screw meshes with the upper plate and the lower plate. Therefore, the connection member can be made more difficult to separate from the upper plate and the lower plate.

Further, an insulating member may be provided to cover the detection element.

In this configuration, the sensing element is covered with an insulating member. That is, the insulating member exists between the sensing element and the upper or lower conductive rubber plate surrounding the sensing element. Therefore, insulation is provided between the sensing element and the upper plate or between the sensing element and the lower plate. Therefore, the detection element can be used even if a conductive member is arranged on the surface of the detection element.

Also, the sensing element may include a tape switch.

With this configuration, the tape switch can easily arrange a detection element having a required length at a required location.

In the method of manufacturing an explosion-proof mat switch according to the present invention, an upper plate of conductive rubber and a lower plate of conductive rubber are prepared, and a load of a heavy object is detected between the upper plate and the lower plate. A detection element is arranged, the upper plate and the lower plate are arranged to face each other, and a connection member is attached to electrically and physically connect the upper plate and the lower plate.

In this configuration, the upper and lower plates are connected by connecting members. A connecting member physically secures the upper and lower plates. The upper plate and the lower plate are made of conductive rubber. Also, the upper plate and the lower plate have the same potential due to the connection member. As a result, potential imbalance between the upper plate and the lower plate can be eliminated. Therefore, the explosion-proof mat switch can prevent the generation of sparks simply by grounding either the upper plate or the lower plate. Therefore, the manufacturer can obtain an explosion-proof mat switch that satisfies the standard of intrinsically safe explosion-proof construction.

According to this invention, the standard for intrinsically safe explosion-proof construction can be fully satisfied.

FIG. 1A is a perspective view of an explosion-proof mat switch 1 according to the first embodiment. FIG. 1B is a plan view of the explosion-proof mat switch 1. FIG. FIG. 2 is an exploded perspective view of the explosion-proof mat switch 1. FIG. FIG. 3(A) is a schematic cross-sectional view of the explosion-proof mat switch 1 cut along II in FIG. 1(B). FIG. 3B is an enlarged cross-sectional view of a region surrounded by a dashed line A in FIG. 3A. FIG. 4 is a flow chart showing a method of manufacturing the explosion-proof mat switch 1. As shown in FIG. FIGS. 5A and 5B are diagrams for explaining an example of how to use the explosion-proof mat switch 1. FIG. FIGS. 6A to 6C are diagrams for explaining modified examples 1 to 3 of the upper plate 11 or the lower plate 12 according to the first embodiment. FIGS. 7A and 7B are diagrams for explaining modification examples 4 and 5 of the insert nut 14 according to the first embodiment.

FIG. 1A is a perspective view of an explosion-proof mat switch 1 according to the first embodiment. FIG. 1B is a plan view of the explosion-proof mat switch 1. FIG. FIG. 2 is an exploded perspective view of the explosion-proof mat switch 1. FIG. FIG. 3(A) is a schematic cross-sectional view of the explosion-proof mat switch 1 cut along II in FIG. 1(B). FIG. 3B is an enlarged cross-sectional view of a region surrounded by a dashed line A in FIG. 3A. In addition, FIG. 1B shows the frame plate 13 and the tape switch 15 with broken lines through the upper plate 11 . Moreover, each figure omits wirings, such as a lead-out cable. Hereinafter, the length direction (horizontal direction) of the explosion-proof mat switch 1 is defined as the X-axis direction, the width direction (vertical direction) is defined as the Y-axis direction, and the thickness direction is defined as the Z-axis direction.

As shown in FIGS. 1(A), 1(B), 2, and 3(A), the explosion-proof mat switch 1 includes an upper plate 11, a lower plate 12, a frame plate 13, and an insert nut. 14 and a tape switch 15 . The upper plate 11 and the lower plate 12 are rectangular flat plates. The frame plate 13 is a rectangular flat plate and has a rectangular opening 16 in the center. The frame plate 13 may be a single flat plate with an opening 16 formed therein, may be formed by combining a plurality of members to form the shape of the frame plate 13, or may be a single elongated rubber plate. may be formed in a ring shape by joining the ends of each other. The shapes of the upper plate 11, the lower plate 12, and the frame plate 13 are not limited to rectangular, and may be, for example, circular or triangular.

The upper plate 11, the lower plate 12, and the frame plate 13 are stacked in the order of the lower plate 12, the frame plate 13, and the upper plate 11 along the Z-axis direction. The lower plate 12 is arranged so as to face the upper plate 11 . The frame plate 13 is arranged between the upper plate 11 and the lower plate 12 . The frame plate 13 functions as a spacer that separates the upper plate 11 and the lower plate 12 by a predetermined distance. Thereby, a space 17 surrounded by the upper plate 11, the lower plate 12, and the frame plate 13 is formed. Therefore, even if the upper plate 11 and the lower plate 12 are flat, the upper plate 11, the lower plate 12, and the frame plate 13 can secure the space 17 in which the tape switch 15 is arranged.

The tape switch 15 is arranged on the main surface of the lower plate 12 on the side facing the upper plate 11 side. Thereby, the tape switch 15 is arranged between the upper plate 11 and the lower plate 12 . The tape switch can be cut to the required length for use. A plurality of tape switches 15 are arranged in parallel in the Y-axis direction so as to cover substantially the entire space 17 . Note that the arrangement of the tape switches 15 is not limited to the example shown in FIG. 2 and the like. The tape switch 15 can be easily arranged in a required portion of the space 17 in accordance with the specification of the explosion-proof mat switch 1 to have a required length.

Also, the upper plate 11, the lower plate 12, and the frame plate 13 are each made of conductive rubber. Therefore, the upper plate 11, the lower plate 12, or the frame plate 13 can easily release electric charges to the outside by connecting a ground wire. The conductivity of the conductive rubber can be appropriately changed in design according to the specifications of the explosion-proof mat switch 1. FIG. Conductive rubbers also include polymeric materials such as, for example, synthetic rubbers or natural rubbers (NR). Examples of synthetic rubbers include nitrile butadiene rubber (NBR) and chloroprene rubber (CR).

The tape switch 15 is a tape-shaped switch. The tape switch 15 is turned on, for example, when a pressing force is applied to the tape switch 15 by a person getting on the upper plate 11 . The tape switch 15 constitutes a detection element together with a circuit (not shown). That is, tape switch 15 is part of the sensing element in the present invention. It should be noted that the detection element may be any element as long as it can detect the load of a heavy object. In addition to the tape switch 15, for example, a strain gauge, a piezoelectric sensor, or the like can be used as the detection element.

Tape switch 15 is covered with film 18 . Film 18 is an example of an insulating member. A film 18 exists between the tape switch 15 and the top plate 11 and between the tape switch 15 and the bottom plate 12 . Therefore, the tape switch 15 and the upper plate 11 and the tape switch 15 and the lower plate 12 are insulated. Therefore, the tape switch 15 can be used for the explosion-proof mat switch 1 even if the tape switch 15 has a conductive member arranged on its surface.

A total of eight insert nuts 14 are attached to each of the four corners of the explosion-proof mat switch 1 . As shown in FIG. 3A, the insert nut 14 is fitted in the explosion-proof mat switch 1 so as to pass through the upper plate 11, the lower plate 12, and the frame plate 13 along the Z-axis direction. Thereby, the insert nut 14 physically connects the upper plate 11 , the lower plate 12 and the frame plate 13 .

The insert nut 14 is an example of a connecting member in the present invention. In this embodiment, the insert nut 14 is a tubular fastening part that can be embedded in the upper plate 11 , the lower plate 12 and the frame plate 13 . The insert nut 14 has a through hole 19 . A female screw 21 is formed on the inner circumference of the through hole 19 . A user can easily connect the ground wire by simply inserting a male screw into the female screw 21 and clamping the ground wire between the male screws. Therefore, the explosion-proof mat switch 1 can be easily grounded through the ground wire. Grounding of the ground wire will be described later in detail. A general-purpose insert nut can be used as the insert nut 14 . As a general-purpose insert nut, Ensat or the like having threads formed on the inner and outer circumferences, which will be described later, can be used.

A male thread 22 is formed on the outer periphery of the insert nut 14 . Thereby, the threads of the male screw 22 mesh with the upper plate 11 , the lower plate 12 and the frame plate 13 . Therefore, the male screw 22 can be firmly connected to the upper plate 11 , the lower plate 12 and the frame plate 13 . Therefore, the insert nut 14 becomes more difficult to separate from the upper plate 11 , the lower plate 12 and the frame plate 13 . The insert nut 14 may be formed with either one of the female thread 21 on the inner periphery and the male thread 22 on the outer periphery.

The insert nut 14 is not limited to one having a screw thread, and may have an uneven surface other than a screw thread. In this case, the insert nut 14 can be firmly connected to the upper plate 11, the lower plate 12, and the frame plate 13 due to the uneven shape of the outer periphery.

The insert nut 14 is made of a conductive material. The insert nut 14 is made of metal such as SUS. Thereby, the insert nut 14 electrically connects the upper plate 11 , the lower plate 12 and the frame plate 13 . The upper plate 11 , the lower plate 12 and the frame plate 13 have the same potential due to the insert nut 14 . The explosion-proof mat switch 1 can eliminate uneven potentials of the upper plate 11 , the lower plate 12 and the frame plate 13 . Therefore, the explosion-proof mat switch 1 can be grounded from the top plate 11, the bottom plate 12, the frame plate 13, and the insert nut 14 simply by grounding any one of the top plate 11, the bottom plate 12, the frame plate 13, or the insert nut 14. Electric charges can be quickly released to the outside. Thereby, the electric energy of the upper plate 11, the lower plate 12, the frame plate 13, or the insert nut 14 is always close to zero, and the generation of sparks can be prevented. If the surface of the explosion-proof mat switch 1 is conductive and grounded, discharge on the surface can be prevented even if the upper plate 11, the lower plate 12, or the frame plate 13 is made of insulating rubber. Here, if an explosive gas enters the internal space, there is a possibility that discharge will occur in the internal space. However, in the explosion-proof mat switch 1 of the present embodiment, since the potentials of the upper plate 11, the lower plate 12, and the frame plate 13 are not biased, the inside surrounded by the upper plate 11, the lower plate 12, and the frame plate 13 Discharge in space is prevented. Therefore, the explosion-proof mat switch 1 can be used in a dangerous area such as a combustible gas atmosphere. In this way, the explosion-proof mat switch 1 satisfies the standard for intrinsically safe explosion-proof construction.

Note that the insert nuts 14 need only be fitted in locations where the upper plate 11, the lower plate 12, and the frame plate 13 are physically connected. can be changed as appropriate. However, since the insert nuts 14 of this embodiment are arranged at the four corners, it is possible to prevent the upper plate 11, the lower plate 12, and the frame plate 13 from turning over from the corners.

Moreover, the upper plate 11, the lower plate 12, and the frame plate 13 made of conductive rubber have a certain amount of electrical resistance, and there is a possibility that the farther away they are from the insert nut 14, the different their potentials will be. However, since the insert nuts 14 of the present embodiment are arranged at a plurality of locations, it is possible to suppress potential imbalance at each location. In particular, since the insert nuts 14 are arranged at the four corners, the upper plate 11, the lower plate 12, and the frame plate 13 can be made substantially at the same potential. Therefore, even if the ground wire is connected to only one of the insert nuts 14, the electric energy can be suppressed over the entire upper plate 11, lower plate 12, and frame plate 13. FIG.

FIG. 4 is a flow chart showing a method of manufacturing the explosion-proof mat switch 1. As shown in FIG. As shown in FIG. 4, the manufacturer first prepares an upper plate 11, a lower plate 12, and a frame plate 13 (S1). The manufacturer covers the tape switch 15 with the film 18 in advance. The manufacturer arranges a plurality of tape switches 15 covered with a film 18 on the lower plate 12, as shown in FIG. 2 (S2). The tape switch 15 is attached to the lower plate 12 with an adhesive, adhesive, or the like, and fixed to the lower plate 12 .

The manufacturer sequentially stacks the lower plate 12 on which the tape switch 15 is arranged, the frame plate 13 and the upper plate 11 . At this time, the manufacturer arranges the upper plate 11 and the lower plate 12 on which the tape switches 15 are arranged so as to face each other with the frame plate 13 interposed therebetween (S3). Here, the manufacturer may use a drill or the like to form two holes for inserting the insert nuts 14 at each of the four corners of the explosion-proof mat switch 1 . The diameter of the hole for inserting the insert nut 14 is slightly smaller than the diameter of the insert nut 14 . This makes it easier for the manufacturer to attach the insert nut 14 to the upper plate 11, the lower plate 12, and the frame plate 13 by pushing the insert nut 14 into the hole and rotating it with a screwdriver. Thus, the manufacturer attaches the insert nuts 14 to the upper plate 11, the lower plate 12, and the frame plate 13 (S4). Therefore, the manufacturer can manufacture the explosion-proof mat switch 1 that fully satisfies the standards of the intrinsically safe explosion-proof structure.

The explosion-proof mat switch 1 may also include an adhesive for bonding the upper plate 11, the lower plate 12, and the frame plate 13 to each other. When using an adhesive for the explosion-proof mat switch 1, the manufacturer applies the adhesive to the lower plate 12, the frame plate 13, and the upper plate 11, and then attaches the lower plate 12, the frame plate 13, and the upper plate 11. Laminate in order. As a result, the upper plate 11, the lower plate 12, and the frame plate 13 are adhered to each other with the adhesive. Therefore, it is difficult for water, dust, and the like to enter between the upper plate 11 , the lower plate 12 and the frame plate 13 . Therefore, the explosion-proof mat switch 1 is improved in water resistance and durability.

Even when the upper plate 11, the lower plate 12, and the frame plate 13 are adhered with an insulating adhesive, the upper plate 11, the lower plate 12, and the frame plate 13 are electrically connected by the insert nut 14. Therefore, the same potential can be maintained. Also, the upper plate 11, the lower plate 12, and the frame plate 13 may be adhered with a conductive adhesive. In this case, the upper plate 11, the lower plate 12, and the frame plate 13 are also electrically connected via a conductive adhesive. Therefore, even if the insert nut 14 comes off, for example, the same potential can be maintained between the main surfaces of the upper plate 11, the lower plate 12, and the frame plate 13. FIG.

FIGS. 5A and 5B are diagrams for explaining an example of how to use the explosion-proof mat switch 1. FIG. 5(B) is a partial cross-sectional view cut along II-II in FIG. 5(A).

As shown in FIGS. 5A and 5B, the explosion-proof mat switch 1 may be used while being surrounded by a frame member 50. FIG. The frame member 50 has four corner portions 51 and four side portions 52 . The corner portion 51 and the side portion 52 are assembled to form a single frame that covers the explosion-proof mat switch 1 . The corner portion 51 has a through hole 58 . As shown in FIG. 5A, the through hole 58 is fitted with a screw. The frame member 50 is fixed to the floor or the like by connecting the screws to the floor or the like. Further, since the explosion-proof mat switch 1 is surrounded by the frame member 50, the explosion-proof mat switch 1 can also be fixed to the floor or the like.

The corner portion 51 has a front portion 54 , a support portion 55 and a bottom portion 56 . The explosion-proof mat switch 1 is fixed to the frame member 50 while being in contact with part of the front portion 54 and the support portion 55 . The front portion 54 has an opening 59 .

The male screw 53 is fastened to one of the insert nuts 14 of the explosion-proof mat switch 1 . One end of the ground wire 57 is connected to the lug terminal 31 . The male screw 53 is inserted into one of the insert nuts 14 with the lug terminal 31 sandwiched therebetween. The male screw 53 is tightened so as to sandwich the lug terminal 31 . Thus, the insert nut 14 and the male screw 53 connect the ground wire 57 via the lug terminal 31 . Thereby, the explosion-proof mat switch 1 can be grounded via the insert nut 14 , the male screw 53 , the lug terminal 31 and the ground wire 57 . Also, in this case, the connecting portion of the ground wire 57 is generally covered with the front portion 54 . The frame member 50 can prevent a user from stepping on the connecting portion of the ground wire 57 . Further, the lug terminal 31 is sandwiched and fixed between the front portion 54 and the upper surface of the upper plate 11 . Therefore, even if a user hooks his or her foot on the ground wire 57 , a load is less likely to be applied to the connecting portion of the male screw 53 of the lug terminal 31 . Therefore, the ground wire 57 is prevented from coming off.

FIG. 6A is a diagram for explaining Modification 1 of the upper plate 11 or the lower plate 12 according to the first embodiment. FIG. 6B is a diagram for explaining Modification 2 of the upper plate 11 or the lower plate 12 according to the first embodiment. FIG. 6C is a diagram for explaining Modification 3 of the upper plate 11 or the lower plate 12 according to the first embodiment. In the description of Modifications 1 to 3, only the differences from the upper plate 11 or the lower plate 12 of the explosion-proof mat switch 1 will be explained, and the rest will be omitted.

As shown in FIG. 6A, the explosion-proof mat switch 61 according to Modification 1 includes a top plate 71 instead of the top plate 11 and the frame plate 13 . The upper plate 71 has a substantially rectangular parallelepiped shape with an open bottom surface. That is, the upper plate 71 has a shape in which the upper plate 11 and the frame plate 13 according to the first embodiment are integrated. The opening of the upper plate 71 is closed by the lower plate 12 . Thereby, the space 17 can be formed by the upper plate 71 and the lower plate 12 . Therefore, the explosion-proof mat switch 61 can be formed with a small number of members.

The insert nut 14 is fitted in the explosion-proof mat switch 61 so as to pass through the upper plate 71 and the lower plate 12 along the Z-axis direction. Thereby, the insert nut 14 can physically and electrically connect the upper plate 71 and the lower plate 12 .

As shown in FIG. 6B , the explosion-proof mat switch 62 according to Modification 2 includes a lower plate 72 instead of the lower plate 12 and the frame plate 13 . The lower plate 72 has a substantially rectangular parallelepiped shape with an open upper surface. That is, the lower plate 72 has a shape in which the lower plate 12 and the frame plate 13 according to the first embodiment are integrated. The opening of the lower plate 72 is closed by the upper plate 11 . Thereby, the space 17 can be formed by the upper plate 11 and the lower plate 72 . Therefore, the explosion-proof mat switch 62 can be formed with a small number of members.

The insert nut 14 is fitted in the explosion-proof mat switch 61 so as to pass through the upper plate 11 and the lower plate 72 along the Z-axis direction. Thereby, the insert nut 14 can physically and electrically connect the upper plate 11 and the lower plate 72 .

As shown in FIG. 6C, the explosion-proof mat switch 63 according to Modification 3 includes upper and lower plates 73 instead of the upper plate 11, lower plate 12, and frame plate 13. As shown in FIG. The upper and lower plates 73 are flat plates in the form of expanded rectangular parallelepipeds before being assembled. When the upper and lower plates 73 are assembled, they have a rectangular parallelepiped shape with a space 17 inside.

Therefore, the tape switch 15 can be placed in the space 17 of the explosion-proof mat switch 63 by closing the ends of the upper and lower plates 73 after placing the tape switch 15 in the space 17 . Therefore, the explosion-proof mat switch 63 can be formed with a small number of members.

The insert nut 14 is fitted in the explosion-proof mat switch 61 so as to pass through the assembled upper and lower plates 73 along the Z-axis direction. Thereby, the insert nut 14 can physically and electrically connect the ends of the upper and lower plates 73 .

FIG. 7A is a diagram for explaining Modification 4 of the insert nut 14 according to the first embodiment. FIG. 7B is a diagram for explaining Modified Example 5 of the insert nut 14 according to the first embodiment. In the description of modifications 4 and 5, only the differences from the insert nut 14 of the explosion-proof mat switch 1 will be described, and the rest will be omitted.

As shown in FIG. 7A, the explosion-proof mat switch 64 according to Modification 4 includes a connecting member 81. As shown in FIG. The connection member 81 includes a tubular portion 82 and a flange 83 . The cylindrical portion 82 is attached to the explosion-proof mat switch 64 so as to pass through the upper plate 11 , the lower plate 12 and the frame plate 13 . Flanges 83 are formed at both ends of the tubular portion 82 . The flange 83 can prevent the tubular portion 82 from moving along the Z-axis direction.

Before the connection member 81 is attached to the explosion-proof mat switch 64, the manufacturer, for example, sums the lengths in the Z-axis direction of the upper plate 11, the lower plate 12, and the frame plate 13 in the Z-axis direction. Prepare a longer one. The connecting member 81 partially protrudes outside the upper plate 11 , the lower plate 12 and the frame plate 13 when fitted into the upper plate 11 , the lower plate 12 and the frame plate 13 . After being fitted into the upper plate 11, the lower plate 12, and the frame plate 13, the connecting member 81 protrudes from the upper plate 11, the lower plate 12, and the frame plate 13 other than the cylindrical portion 82, and is attached to the Z-axis direction. A flange 83 is formed extending parallel to the XY plane by applying pressure from above and below.

Alternatively, the connection member 81 may be composed of two parts divided into upper and lower parts in the Z-axis direction by the cylindrical part 82 before assembly. In this case, the two parts are joined after being fitted into the upper plate 11, the lower plate 12, and the frame plate 13 from above and below in the Z-axis direction. Thereby, the connection member 81 can be attached to the upper plate 11 , the lower plate 12 and the frame plate 13 . Moreover, the connection member 81 can electrically and physically connect the upper plate 11 , the lower plate 12 , and the frame plate 13 .

As shown in FIG. 7B, the explosion-proof mat switch 65 according to Modification 5 includes a connection member 74 instead of the insert nut 14 . The connection member 74 has a support portion 75 and a peripheral portion 76 . The peripheral portion 76 is attached to the explosion-proof mat switch 65 so as to contact cross sections of the upper plate 11 , the lower plate 12 and the frame plate 13 . The supporting portion 75 is continuous with the peripheral portion 76 and is bent parallel to the XY plane above the upper plate 11 and below the lower plate 12 .

For example, the connection member 74 is arranged so as to sandwich the periphery of the upper plate 11, the lower plate 12, and the frame plate 13, and then, by applying pressure from above and below in the Z-axis direction, the upper plate 11, the lower plate 12, and the frame plate 13 are arranged. It can be attached to the lower plate 12 and the frame plate 13 . Thereby, the connection member 74 covers the connection portions of the upper plate 11 , the lower plate 12 and the frame plate 13 . Between the upper plate 11, the lower plate 12, and the frame plate 13, it is difficult for water, dust, etc. to enter. Therefore, the explosion-proof mat switch 65 is improved in water resistance and durability. Also, as with the insert nut 14, the formation of a hole can be omitted.

The description of the above-described embodiments should be considered illustrative in all respects and not restrictive. The scope of the invention is indicated by the claims rather than the above-described embodiments. Furthermore, the scope of the present invention is intended to include all modifications within the meaning and scope of equivalents of the claims.

Reference Signs List 1 Explosion-proof mat switch 11 Upper plate 12 Lower plate 13 Frame plate 14 Insert nut (connecting member)
15... Tape switch (part of detection element)
21 Female screws 22, 53 Male screws 57 Earth wires 61, 62, 63, 64, 65 Explosion-proof mat switch 71 Upper plate 72 Lower plate 73 Upper and lower plates (upper plate and lower plate)
74 ... Connection member 81 ... Connection member

Claims (8)

a top plate of conductive rubber;
a lower plate of conductive rubber arranged to face the upper plate;
a detection element disposed between the upper plate and the lower plate for detecting the load of a heavy object;
a connection member that electrically and physically connects the upper plate and the lower plate;
comprising a
Explosion-proof mat switch. an adhesive that adheres the upper plate and the lower plate to each other;
The explosion-proof mat switch according to claim 1. further comprising a conductive rubber frame plate disposed between the upper plate and the lower plate;
The explosion-proof mat switch according to claim 1. wherein the connecting member includes an insert nut;
The explosion-proof mat switch according to any one of claims 1 to 3. The connection member has at least one of an inner peripheral female thread and an outer peripheral male thread.
The explosion-proof mat switch according to claim 4. Equipped with an insulating member that covers the detection element,
The explosion-proof mat switch according to any one of claims 1 to 5. the sensing element includes a tape switch;
The explosion-proof mat switch according to any one of claims 1 to 6. Prepare an upper plate of conductive rubber and a lower plate of conductive rubber,
A detection element for detecting the load of a heavy object is arranged between the upper plate and the lower plate,
arranging the upper plate and the lower plate to face each other;
attaching a connection member that electrically and physically connects the upper plate and the lower plate;
A method for manufacturing an explosion-proof mat switch.

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