JPH0458131B2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of Industrial Application This invention relates to a pressure switch that detects fluid leakage, etc. based on detecting pressure changes of various fluids such as gas and liquid. More specifically, the present invention relates to a pressure switch with good workability and assemblability of component parts.

(b) Background of the Invention Conventionally, a pressure switch using a bellows has been disclosed in, for example, Japanese Utility Model Application Publication No. 54-7378.

The structure of the conventional pressure switch described above is such that a cap that protects the bellows is formed long and deep to cover the entire bellows, and a mounting flange is connected to this cap to attach it to a mounting part. ing.

In the case of a cap constructed in this way, corrosion resistance and rigidity are required, so the material used is a hard material such as stainless steel and thick.
For example, if the cap is formed by press working, as described above, the cap is long and deep, so the process involves deep drawing, which causes problems in the process, increases the number of process steps, and has poor workability.

Also, when fixing the aforementioned cap to a fixed part such as the main body to cover the bellows, because the cap is deep, the positional relationship with the bellows cannot be determined during assembly.
The problem is that it is difficult to assemble.

(c) Problems to be Solved by the Invention Therefore, an object of the present invention is to provide a pressure switch whose protective cap of the bellows and mounting pressure receiving flange are easy to process and assemble.

(d) Means for Solving the Problems This invention provides a corrosion-resistant bellows that expands and contracts in response to changes in fluid pressure, and a mechanism that acts on the inner surface of the bottomed portion of the bellows and moves back and forth in conjunction with the expansion and contraction movement of the bellows. The pressure switch is equipped with a plunger that moves forward and backward, and an action switch that opens and closes between contact parts in conjunction with the forward and backward movement of the plunger, and the pressure switch has approximately half of the upper and lower sides surrounded by the outer periphery of the bellows. A protective cap and a pressure-receiving flange are disposed, and the protective cap is formed into a cylinder with a bottom, and a gas supply port is formed at the center of the upper surface, and a fixing protrusion is formed at the periphery of the lower end. The pressure receiving flange is formed into a cylindrical body, and has a flange extending radially outward on the upper end side to fix the protruding piece of the protective cap, and has a mounting opening formed in the flange, and a lower end side. It is characterized in that it is a pressure switch fixed to the fixed part.

(E) Effects of the Invention According to this invention, the member covering the outer periphery of the bellows is made up of two members: the protective cap and the pressure receiving flange, which surround approximately half of the upper and lower parts, so that the pressure receiving flange does not need to be made of a material for mounting. Even if rigidity is provided, the length is about half that of the bellows, making it easier to process, and since there is no need for rigidity in the protective cap, a thinner material can be used. , which also improves workability.

Furthermore, when assembling the above-mentioned protective cap and pressure receiving flange, etc., when the pressure receiving flange is combined with the bellows, since the pressure receiving flange is short, the bellows will protrude from the pressure receiving flange, and this will allow you to check the condition of the bellows and assemble it. Work becomes easier.

Further, even if the protective cap is fixed to the pressure receiving flange afterwards, since the protective cap is also short, the positional relationship with the bellows can be easily grasped, and assembly is facilitated.

In addition, the mounting opening is formed on the flange at the middle position between the top and bottom of the bellows, and this middle position is used as the mounting part for the fixed part, so the bellows side of the pressure switch does not protrude too much to the detection side of the mounting body, making it optimal. As a result, the degree of freedom in installation is increased, and the external design is good.Furthermore, the presence of the flange increases rigidity and ensures protection of the bellows.

(F) Embodiment of the Invention An embodiment of the invention will be described in detail below based on the drawings.

The drawing shows a pressure switch used for gas leak detection for city gas, LPG, etc.
In FIG. 4, this pressure switch 11 includes a bellows 12 that expands and contracts in response to gas pressure, and a bellows 12 that expands and contracts in response to gas pressure.
Plunger 1 moves up and down in conjunction with the expansion and contraction movement of 2.
3, and an action switch 14 that is opened and closed in conjunction with the vertical movement of the plunger 13.

The above-mentioned bellows 12 is formed into a cylindrical body with a bottom, and, as is well known, has uneven bent portions 15 formed on its circumferential surface that allow expansion and contraction at regular intervals in the axial direction, and is made of a metal with good corrosion resistance. It is formed by electrodeposition (metsuki method) to a very thin thickness of about 15 to 20 microns.

The center portion of the upper surface corresponding to the bottomed portion of the bellows 12 is set as a pressure receiving surface 16, and a corrosion-resistant and thin metal reinforcing plate 17 is fixed to this pressure receiving surface 16. Thereby, the thin pressure receiving surface 16 has a predetermined strength that does not deform even when subjected to gas pressure.

Further, the periphery of the open portion of the bellows 12 has a radially extending flange 18 for fixing, and the periphery of the flange 18 is airtightly fixed by welding and fixing means to be described later.

Further, a protective cap 19 as a pressure receiving unit and a pressure receiving flange 20 are arranged around the outer circumference of the bellows 12, and a case 21 for supporting the bellows 12 and the plunger 13 is arranged inside the bellows 12. Ru.

The above-mentioned protective cap 19 is formed into a bottomed cylindrical body that can surround the upper half of the outer periphery of the bellows 12, and a small diameter gas supply port 22 is opened at the center of the upper surface corresponding to the bottomed side. Projecting pieces 23 for fixing the cap are equally divided and protruded from the periphery of the open side of the cylinder.

Further, the pressure receiving flange 20 is provided with a flange 24 extending radially outward in order to weld and integrate the above-mentioned projecting pieces 23 on the upper end side, and the pressure receiving flange 20 is a cylinder surrounding the lower half of the outer periphery of the bellows 12. formed in the body,
At the periphery of the flange 24, extending portions 26, which are formed by opening attachment ports 25 for attachment to a device main body (not shown), are provided so as to protrude equally divided in the circumferential direction.

By the way, the above-mentioned bellows 12, metal reinforcing plate 17, protective cap 19 and pressure receiving flange 20
Since it comes into direct contact with gas through the gas supply port 22, it is suitable to use a metal with good corrosion resistance and airtightness, such as stainless steel.

The flange 18 of the bellows described above is airtightly welded and fixed between the lower end surface of the pressure receiving flange 20 and a retaining plate 27, which will be described later, while being sandwiched from above and below. As shown in FIG.
7 are sandwiched from above and below in a sandwich pattern with the flange 18 in the middle, and the entire outer circumferential surface of the overlapped portion is fused and joined by laser welding or the like. As a result, the welded fixing part is airtightly sealed, and there is no fear of gas leakage from the fixing part, and the fixing part can be efficiently fixed.

The above-mentioned retainer plate 27 is made of a laser-weldable metal material such as stainless steel and has a disc shape, and the inner circumferential portion of the retainer plate 27 is integrally insert-molded during resin molding of the case 21, which will be described later. The upper surface of the outer peripheral portion of the retaining plate 27 after insert molding is exposed, and this exposed upper surface is provided as a seat surface that supports the lower surface of the flange 18 described above. It will be done.

Further, the case 21 has an upper part interposed in the hollow interior 28 of the bellows 12, and is provided in a small diameter part to shorten the switch length in the pressure receiving direction, and a lower part is provided in a large diameter part for fixing the retaining plate. Resin molded into a stepped cylinder.

By the way, a plunger insertion hole 29 is vertically penetrated in the central axis direction of the upper side of the case, and a lower surface recess 30 is formed on the lower surface side communicating with this plunger insertion hole 29.
A base 31 on which an action switch, which will be described later, is mounted is integrally mounted in the lower recess 30.

The above-mentioned plunger 13 is allowed to move vertically and is inserted into the plunger insertion hole 29, and has a contact 32 at the upper end that can be contacted from the inner surface of the pressure receiving surface 16 of the bellows 12, and this contact 32 is attached to the case. It is provided in a state that protrudes from the upper surface of 21. In addition, at the lower end, there is a pair of left and right pushers 33, 33 branched on both sides for opening and closing an action switch to be described later.
is provided. As a result, the plunger 13
moves up and down in direct response to the up and down movement of the bellows 12, which expands and contracts in response to gas pressure, and as a result operates an action switch to be described later.

The aforementioned base 31 is fitted and fixed into a lower surface recess 30 of the case 21, which is opened in accordance with the size of the base 31, and locking recesses 34 are carved on both sides of the base 31. is engaged and fixed in a correspondingly protruding locking recess 35 in the lower surface recess 30. 36 is an atmospheric ventilation hole.

An action switch, which will be described later, is formed on the upper surface of the base 31. This action switch 14 has a first fixed terminal 37 and a second fixed terminal 3.
8, a plate spring body 39, and a biasing spring piece 40, and both fixed terminals 37,
Reference numeral 38 is provided by integral insert molding during resin molding of the base 31, and after insert molding, the first and second fixed terminals 37 and 38 have their upper ends protruding from the upper surface of the base 31, respectively. 1. Set to the second fixed contacts 37a, 38a,
The lower end portions are respectively provided vertically from the lower surface of the base 31 and are provided as first and second external terminals 37b and 38b.

Of these, the first fixed contact 37a has an inverted L shape and protrudes from one side of the upper surface of the base 31, and a non-conductive OFF contact 41 is protruded from the upper surface of the base 31 facing this L-shaped bent piece. has been done. Also, the second
The fixed contact 38a has a flat plate shape and projects from the center of the upper surface of the base 31, and on both sides of the contact 38a,
Leaf spring locking grooves 42 and 43, which will be described later, are formed respectively, and a leaf spring locking protrusion 44 is protruded from the other side of the upper surface of the base 31.

Note that these fixed contacts 37a, 38a protrude from a low step portion 45 on the base 31, and when the base 31 is attached to the case 21, these fixed contacts 37a, 38a are inserted into the lower surface recess 30 of the case 21.
and a low step portion 45 of the base 31.

The above-mentioned leaf spring main body 39 has a locking port 47 opened at one end that is locked to the above-mentioned leaf spring locking protrusion 44, and the other end is movable by allowing vertical movement about this locking portion as a fulcrum. It is set in the piece 48 and is located between the first fixed contact 37a and the OFF contact 41 described above.

Furthermore, the central part of the leaf spring body 39 has a fixing piece 49 whose one end is fixed to the leaf spring body 39 and the other end is set as a free end.
The plate spring main body 39 is fixedly supported on the base 31 by the free end side of the plate spring 9 being locked in one of the plate spring locking grooves 42 of the second fixed contact 38a. Further, an opening 50 is provided in the free end side of the fixed piece 49 by hollowing out the center thereof, and a locking protrusion 51 protrudes from the side edge of the opening 50 on the first fixed contact side. 51, one end of the biasing spring piece 40 formed in an arc shape is locked, and the other end is locked in a slightly compressed state in the other leaf spring locking groove 43 of the second fixed contact 38a. be done.

As a result, the movable piece 48 side of the leaf spring body 39 is urged into contact with the first fixed contact 37a by the urging force based on the restoring force of the urging spring piece 40.

A pair of left and right pushers 33, 33 of the plunger 13 described above are provided in contact with both sides of the center portion of the upper surface of the leaf spring body 39 so as to be freely depressed.

When the pressure switch configured in this way is attached to the main body of the device, the bellows 12
is compressed by a predetermined amount, and this compressed bellows 12
The plunger 13 moves downward based on this, pushing down the lower leaf spring body 39, and the movable piece 48 is used in the OFF state away from the first fixed contact 37a.

If a gas leak occurs while the pressure switch 11 is in use, the gas pressure against the bellows 12 decreases in the initial state of the gas leak, and the bellows 12 responds to this minute pressure change by reducing the bellows itself. The elastic restoring force causes the plunger to naturally expand, and the pressing force on the plunger 13 is released. As a result, the plunger 13 moves upward, and the movable piece 48 also moves upward, so that the first fixed contact 3
7a, and the connection between both fixed contacts 37a and 38a via the movable piece 48 brings them into the ON state. Via this electrical signal, an appropriate warning against gas leakage is issued from the device main body, such as flashing a lamp or emitting an alarm sound.

[Brief explanation of drawings]

The drawings show an embodiment of the present invention, and FIG. 1 is an exploded perspective view showing a pressure switch for detecting gas leaks;
FIG. 2 is a perspective view showing the external appearance, FIG. 3 is an enlarged vertical cross-sectional view, and FIG. 4 is an enlarged plan view of the action switch. 11...Pressure switch, 12...Bellows, 1
3... Plunger, 14... Action switch, 16... Pressure receiving surface, 19... Protective cap, 2
0...Pressure receiving flange, 21...Case, 22...
Gas supply port, 23... protrusion, 24... flange,
25...Mounting port, 37a...First fixed contact, 3
8a... Second fixed contact, 39... Leaf spring body, 4
0...Biasing spring piece.

Claims (1)

[Scope of Claims] 1. A corrosion-resistant bellows that expands and contracts in response to fluid pressure changes, with the outer surface side of the bottomed part of the bottomed cylindrical body set as a pressure receiving part, and the opening side peripheral edge fixed to a fixed part; a plunger that acts on the inner surface of the bottomed portion and is supported on the fixed portion so as to be movable forward and backward in conjunction with the expansion and contraction movement of the bellows; and an action switch that opens and closes between contact portions in conjunction with the forward and backward movement of the plunger. The pressure switch is equipped with two members, a protective cap and a pressure-receiving flange, each surrounding approximately the upper and lower halves of the bellows, and the protective cap is attached to a bottomed cylindrical body. a gas supply port is formed at the center of the upper surface, and a fixing protrusion is formed at the peripheral edge of the lower end, and the pressure receiving flange is formed into a cylinder and extends radially outward from the upper end to A pressure switch having a flange for fixing a protruding piece of a protective cap, a mounting opening formed in the flange, and a lower end fixed to the fixing part.