JPH0458132B2 - - 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 in which bellows are efficiently assembled and the switch can be made smaller and lower in cost.

(b) Prior Art Conventionally, this type of pressure switch detects changes in fluid pressure via a pressure receiving element such as a diaphragm or bellows that is sensitive to changes in fluid pressure (for example, Japanese Patent Laid-Open No. 50-27078). Publication, Japanese Unexamined Patent Publication 1983-
Publication No. 120044).

By the way, as is well known, the bellows as the pressure receiving element in the above example is widely used because of its excellent repeatability and high durability. It is fixed by fitting the side to a fixing member or the like.

For this reason, it is necessary to install a straight pipe-shaped fitting part, etc., long in the axial direction on the open end side of the bellows as an example for mounting. It was becoming difficult to adapt. Furthermore, when attaching the bellows, not only is it difficult to position the bellows in the pressure receiving direction, but also the bellows and the corresponding fixing member require highly accurate dimensions for fitting into each other, resulting in high costs.

In addition, there is a method of sandwiching the upper and lower parts of the diaphragm between flanges of a metal casing and welding these three parts by arc welding, for example.
It is disclosed in Publication No. 2855.

However, with this welding method, the casing that houses the switch is also made of metal, so it is necessary to consider insulation from the switch, and it is necessary to provide sufficient space for the switch housing, so there is a problem that it cannot be made compact. Has a point.

(c) Problems to be Solved by the Invention Therefore, an object of the present invention is to provide a pressure switch that has a short bellows and can be mounted with high precision and efficiency.

(d) Means for Solving the Problems In this invention, the outer surface side of the bottomed part of the bottomed cylindrical body is set as a pressure receiving part, and the peripheral edge on the opening side is set as a fixing collar part extending in the outer diameter direction. a corrosion-resistant bellows that expands and contracts in response to changes in fluid pressure; a plunger that acts on the inner surface of the bottomed portion of the bellows and moves forward and backward in conjunction with the expansion and contraction movement of the bellows; and a plunger that moves forward and backward within the bellows. an action switch that opens and closes the contact portions in conjunction with the forward and backward movement of the plunger and is disposed on the bottom side of the case; and an action switch that has the same outer diameter as the flange of the bellows. a pressure-receiving flange having the same outer diameter as the flange of the bellows and serving as a top surface for welding and fixing to the outer circumferential surface of the flange; A pressure switch is provided with a retaining plate insert-molded in the case as a surface, and the outer circumferential surface of the overlapped portion is welded with the collar portion of the bellows being sandwiched from above and below between the seat surface of the pressure receiving flange and the retaining plate. It is characterized by

(E) Effects of the Invention According to this invention, by forming a fixing flange on the opening side periphery of the bellows, the bellows does not need a fitting part extending in the axial direction, and therefore the axial The length in the direction is shortened, and the switch can be reliably miniaturized.

In addition, the flange is sandwiched from above and below in a sandwich-like manner by the pressure-receiving flange and the holding plate, which are set to have the same outer diameter as the flange. By joining, the bellows is accurately positioned and regulated at a predetermined position by the pressure receiving flange and the retaining plate, and the upper and lower surfaces of the collar are supported by the seat surface and stably fixed.

In addition, in this overlapping welded portion, since the three overlapping layers are melted and bonded to each other, sealing performance can be ensured and assembly can be performed easily.

Furthermore, since the above-mentioned holding plate is insert-molded into the case, and the case itself can be made of insulating resin, the action switch installed on the bottom side of the case is configured close to the inside of the case. Therefore, the switch part can be formed compactly, and in addition, since the plunger and the case part supporting the plunger are interposed in the internal space of the bellows, the internal space of the bellows can be used effectively. This allows the entire structure to be efficiently miniaturized.

Moreover, since the case is made of resin, it is not only inexpensive, but also there is no need to consider insulation as described above, which improves the ease of assembly of the action switch.

Furthermore, if the bellows, which expands and contracts in response to fluid pressure changes, is made of a thin film with high sensitivity, it can also be used as a highly sensitive pressure switch that can detect minute pressure changes.

(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, the pressure switch 11 includes a bellows 12 that expands and contracts in response to gas pressure, a plunger 13 that moves up and down in conjunction with the expansion and contraction of the bellows 12, and an opening and closing operation that is performed in conjunction with the up and down movement of the plunger 13. and an action switch 14.

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 bellows 12 has a radially extending flange 18 for fixing on the periphery of the open part, and the flange 18 is 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 outer periphery of the bellows 12, and has a small-diameter gas supply port 2 in the center of the upper surface corresponding to the bottomed side.
2 is opened, and projecting pieces 23 for fixing the cap are equally divided and provided on the periphery of the open side of the bottomed cylinder.

Further, the pressure receiving flange 20 is formed into a cylindrical body having a flange 24 for fixing the above-mentioned protrusions 23 on the upper end side, and the periphery of the flange 24 is attached to the device body (not shown). Extending portions 26 formed by opening mounting holes 25 for mounting are equally divided in the circumferential direction and protrudingly provided.

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 the gas through the gas supply port 22, it is suitable to use a metal with good corrosion resistance and airtightness, such as stainless steel or nickel.

The flange portion 18 of the bellows described above is disposed between the lower end surface of the pressure receiving flange 20 and a retaining plate described later.
are sandwiched from above and below and are welded and fixed in an airtight manner, and as shown in FIG. Tsuba part 1
8 and the outer periphery of the holding plate 27 are sandwiched from above and below in a sandwich-like manner with the flange 18 in the middle, and the entire outer periphery of the overlapped portion is welded using, for example, a laser welding machine 52. While continuously rotating the objects to be welded, the outer circumferential surfaces 53 of the overlapping portions are fused and joined.

As a result, the bellows 12 is accurately positioned and fixed at a predetermined position, and the welded and fixed portion is airtightly sealed, so that there is no fear of gas leakage from the fixed portion, and the bellows 12 is efficiently and easily 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 side interposed in the hollow interior 28 of the bellows 12, and is provided in a small diameter part in order 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 attached to this 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.
will be 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 by the engagement convex portions 35 in the lower surface concave portion 30 that protrude correspondingly thereto. 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 adjacent part on the free end side of the fixed piece 49, and a locking protrusion 51 protruding from the side edge of the first fixed contact side extends through the opening 50. 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.

FIG. 6 shows another embodiment of the present invention, which is a means for improving the welding performance of laser welding, and includes a pressure receiving flange 61 formed with a relatively thick wall.
A circumferential groove 62 is provided in the vicinity of the welded part, and this circumferential groove 6
2 prevents dispersion of welding heat due to laser welding, and as a result, during welding, the pressure receiving flange 61 in the upper layer and the flange 6 of the bellows 63 in the middle layer are
4 and the outer peripheral surface 6 of the overlapping part with the lower layer holder 65
6, the welding heat 67 of the laser pulse can be locally concentrated to perform efficient welding.

[Brief explanation of the drawing]

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 its appearance, Fig. 3 is an enlarged vertical cross-sectional view, Fig. 4 is an enlarged plan view of the action switch, and Fig. 5 is a side view showing how the bellows are attached by a laser welder. , FIG. 6 is an enlarged longitudinal cross-sectional view of the essential parts showing an exploded overlap welded portion in another embodiment of the present invention. 11... Pressure switch, 12, 63... Bellows, 13... Plunger, 14... Action switch, 16... Pressure receiving surface, 18, 64... Flange,
20, 61...Pressure receiving flange, 21...Case,
27, 65... Holding plate, 37a... First fixed contact, 38a... Second fixed contact, 39... Leaf spring body, 40... Biasing spring piece, 53, 66... Outer circumferential surface of overlapping portion.

Claims (1)

[Claims] 1. The outer surface side of the bottomed part of the bottomed cylindrical body is set as a pressure receiving part, and the peripheral edge of the opening side is set as a fixing flange part extending in the outer diameter direction, so as to respond to changes in fluid pressure. a corrosion-resistant bellows that expands and contracts; a plunger that acts on the inner surface of the bottomed portion and moves forward and backward in conjunction with the expansion and contraction of the bellows; and a resin case that supports the plunger so that it can move forward and backward within the bellows. an action switch disposed on the lower surface of the case that opens and closes the contact portions in conjunction with the forward and backward movement of the plunger; and an action switch having the same outer diameter as the flange of the bellows, a pressure-receiving flange provided as an upper seat surface for welding and fixing to the outer peripheral surface; and a pressure-receiving flange having the same outer diameter as the flange of the bellows, and insert-molded in the case as a lower seat surface for welding and fixing to the outer periphery of the flange. A pressure switch comprising: a retaining plate; the flange of the bellows is sandwiched from above and below between the seating surfaces of the pressure receiving flange and the retaining plate, and the outer circumferential surface of the overlapped portion is welded.