JPH0817308A - Pressure switch - Google Patents

Abstract

PURPOSE:To prevent the occurrence of the continuity trouble of an electronic contact by the adhesion of dust by providing a pressure equalizing path with a filter thereby preventing the penetration of dust. CONSTITUTION:Electric contacts 34 and 36 open and close, corresponding to the pressure of the pressure fluid having flown in the inner space 10a of a pressure fluid inflow part 10. At this time, a pressure equalizing hole 38 leads atmospheric pressure as reference pressure to the inner space 14a of an armor case 8. Here, the pressure equalizing hole 38 is provided with a filter 40 made in specified dimension out of specified material. Since this filter 40 passes air but does not pass dust, the penetration of dust into the inner space 14a where the electric contacts 34 and 36 lie can be checked. Hereby, the continuity trouble caused by the adhesion of dust to the electric contacts 34 and 36 is checked.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure switch in which a pressure equalizing passage is formed in an outer case that opens and closes electric contacts in response to pressure to allow the atmosphere to communicate with the internal space.

[0002]

2. Description of the Related Art A pressure switch of this type is used, for example, in a vehicle air conditioner, and its structure is described in, for example, Japanese Patent Laid-Open No.
4-27137 and U.S. Pat. No. 4,939,321.
Known by the issue.

In these known pressure switches, a diaphragm is used as a pressure sensing means in the inner space of the outer case. As the material of the diaphragm, plastic is selected from the viewpoint of pressure response characteristics and life, but a very small amount of gas is used. It has a gas permeation property of permeating through.

Not only is it necessary to apply atmospheric pressure as a reference pressure to the surface of the diaphragm opposite to the pressure sensing side surface, but also due to the gas permeation characteristics of the material of the diaphragm, the pressure sensing side surface on the reference pressure side surface of the diaphragm. In order to prevent the extremely small amount of gas that permeates from the chamber from affecting the reference pressure, the above-mentioned outer case has an even space in the interior space of the outer case that communicates with the atmosphere in the region facing the reference pressure side surface of the diaphragm. A pressure passage is formed.

[0005]

In the conventional pressure switch having the above-mentioned structure, when the pressure switch is used in a vehicle air conditioner, dust in the environment in which the pressure switch is used is externally sealed through the pressure equalizing passage of the outer case. In some cases, it may enter the reference pressure side region of the internal space of the case and adhere to the electric contacts in the reference pressure side region to cause conduction interruption.

The present invention has been made under the above circumstances, and an object of the present invention is to form a pressure equalizing passage which opens and closes an electrical contact in response to a pressure and allows the exterior case to communicate with the atmosphere. In the pressure switch, the influence on the reference pressure by the introduction of atmospheric pressure as the reference pressure into the reference pressure side area of the internal space and the slight amount of gas permeation from the pressure sensing side surface of the diaphragm to the reference pressure side surface. Not only can it be ensured that the above-mentioned problem can be solved, but also dust can be sufficiently prevented from entering into the reference pressure side region of the internal space via the pressure equalizing passage, and the electrical contact in the reference pressure side region can be prevented. An object of the present invention is to provide a pressure switch capable of eliminating defective conduction due to adhesion of dust to the pressure switch, and having a simple structure and easily manufactured.

[0007]

In order to achieve the above-mentioned object of the present invention, a pressure switch according to the present invention opens and closes an electric contact in response to a pressure, and forms an external space in an outer case. A pressure equalizing passage that allows communication with the atmosphere is formed, and a filter is provided in the pressure equalizing passage.

[0008]

The filter provided in the pressure equalizing passage is designed to introduce atmospheric pressure as a reference pressure into the reference pressure side region of the internal space of the outer case through the pressure equalizing passage and to remove the pressure from the pressure sensing side surface to the reference pressure side. It can be sufficiently ensured that the gas that slightly permeates to the surface is discharged into the atmosphere through the pressure equalizing passage and does not affect the reference pressure in the reference pressure side area, and furthermore, in the reference pressure side area of the internal space. It is possible to sufficiently prevent dust from entering through the pressure equalizing passage.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the pressure switch of the present invention will be described in detail below with reference to the accompanying drawings. 1 is a schematic vertical sectional view of an embodiment of the pressure switch of the present invention, and FIG. 2 is a top view of the embodiment of FIG.

The pressure switch of one embodiment is a three-action type, and as shown in FIG. 1, the outer case 8 has an end wall having a pressure fluid inflow hole 10a connected to, for example, a refrigeration cycle pipe line (not shown) of an automobile air conditioner. And a cap-shaped metallic pressure fluid inflow portion 10 formed at the one end, and one end that is closed and one end that is open is connected to the pressure fluid inflow portion 10 with a rubber annular sealing member 12 held in between. And a cylindrical reference pressure portion 14.

The reference pressure portion 14 is made of, for example, a synthetic resin such as PBT (polybutylene terephthalate), and the inner space 10b of the pressure fluid inflow portion 10 and the inner space 14a of the reference pressure portion 14 are circular in peripheral portion. Sealing member 1
It is partitioned by a diaphragm 16 which is hermetically supported by the second member.

The diaphragm 16 is made of, for example, a synthetic resin film in order to be sensitively displaced in response to the pressure of the pressure fluid flowing into the internal space 10b of the pressure fluid inflow portion 10 and to have a long life. However,
This synthetic resin film has a very slight gas permeation property with respect to the pressure fluid.

In the internal space 14a of the reference pressure portion 14, a first breeze spring body 1 is arranged adjacent to the diaphragm 16 and has a plurality of breeze springs overlapped on the surface on the diaphragm side.
No. 8 supporting the first pressure receiving piston 20, and a second beaker which is arranged adjacent to the first pressure receiving piston 20 and has a plurality of bevel springs overlapped on the surface of the first pressure receiving piston 20 side. And a second pressure receiving piston 24 supporting the tongue 22.

Then, these first pressure receiving pistons 20
And the second pressure receiving piston 24 are interposed between the surface of the second pressure receiving piston 24 on the opposite side of the first pressure receiving piston 20 and the inner peripheral surface of the internal space 14a of the reference pressure portion 14. The second pressure spring piston 22 is urged toward the diaphragm 16 by the third pressure spring piston 26, and the second pressure spring piston 24 is supported by the second spring spring body 22. And the first compression spring body 20 supported by the first pressure receiving piston 20.
Are brought into contact with the diaphragm 16.

The central portion of the first disc spring body 18 is raised above the corresponding supporting surface of the first pressure receiving piston 20 toward the diaphragm 16, and the second disc spring body 18 is provided.
Of the second pressure receiving piston 24 floats from the corresponding bearing surface of the second pressure receiving piston 24 to the side of the first pressure receiving piston 20.

The first pressure receiving piston 20, the second compression spring body 18, and the second pressure receiving surface are provided on the surface of the first compression spring body 18 at the center of the first compression spring piston 20. One end of a cylindrical first push rod 28 that penetrates the piston 24 and extends toward the closed one end of the reference pressure portion 14 is fixed, and the first push rod 2
A first pressure receiving piston 20 is slidably supported in the longitudinal direction.

The first push rod 28 further includes a second push rod 28.
The second pressure receiving piston 2 is provided at the center of the flat spring body 22.
4 is inserted into a central hole of a cylindrical second push rod 30 which has one end fixed to the surface thereof and which is penetrated by the second pressure receiving piston 24 and extends toward the closed one end of the reference pressure portion 14. It is also supported by the second push rod 30 so as to be slidable in the longitudinal direction.

A second push rod 30 is surrounded by the surface of the second pressure receiving piston 24 on the closed one end side of the reference pressure portion 14, and the second push rod 30 is slidably supported in the longitudinal direction. The third push rod 31 having a cylindrical shape is formed.

The first push rod 28, the second push rod 30, and the third push rod 31 are the third.
The projecting length from the flat spring body 26 toward the closed one end of the reference pressure portion 14 is shortened in the order in which the pressure is increased.

As shown in FIGS. 1 and 2, two pairs of connection terminals 32 project in the longitudinal direction of the reference pressure portion 14 on the end wall 14b closing one end of the reference pressure portion 14 of the outer case 8. The four connecting terminals 32 projecting outward from the reference pressure portion 14 are fixed to the end wall 14b.
4 is surrounded by an annular protective skirt portion 14c formed so as to project in the longitudinal direction and is protected from an external force.

The inner ends of the pair of connection terminals 32 in the internal space 14a of the reference pressure portion 14 constitute a normally closed switch 34 using one elastic contact piece 32a, as shown in FIG. The elastic contact piece 32 a of the normally closed switch 34 faces the protruding end surface of the first push rod 28.

In the internal space 14a of the reference pressure portion 14, another
As shown in FIG. 1, the inner ends of the pair of connecting terminals 32 constitute a normally open switch 36 using two elastic contact pieces 32b and 32c. First
Push rod 28 is movably pierced in its longitudinal direction, and the elastic contact piece 32b on the side of the third flat spring body 26
Also, the second push rod 30 also penetrates movably in its longitudinal direction.

In the normally open switch 36, the second push rod 30 does not pass through the elastic contact piece 32b farther from the third flat spring body 26, and the second push rod 30 does not penetrate.
Of the third push rod 31 do not pass through the elastic contact piece 32c on the side of the third flat spring body 26, and the protruding end faces of the third push rod 31 face each other. There is.

The end wall 14 of the reference pressure portion 14 of the outer case 8
A pressure equalizing hole 38 that communicates the internal space 14a of the reference pressure portion 14 with the external space is formed in b. The pressure equalizing hole 38 is open in a region surrounded by the protective skirt portion 14c on the end wall 14b, and is surrounded by the protective skirt portion 14c.
When a connection plug (not shown) is connected to the pair of connection terminals 32, the connection plug is covered with the connection plug, but the communication is secured.

The opening of the pressure equalizing hole 38 on the external space side is countersunk to form a step 38a as shown in FIGS. 1 and 3, and a filter 40 is fixed to the step 38a by a filter retainer 42. There is. The filter 40 is, for example, nylon 6
6 is woven so as to form a mesh of approximately 10 micrometers, and allows air to pass through but does not allow dust to pass through.

The filter stopper 42 is made of the same material as that of the reference pressure portion 14, and has a through hole 42a formed in the center thereof so as not to close the pressure equalizing hole 38. The filter retainer 42 is fixed by being pressed into the pressure equalizing hole 38.

The pressure equalizing hole 38 serves to apply atmospheric pressure as a reference pressure to the internal space 14a of the reference pressure portion 14 which is separated from the internal space 10b of the pressure fluid inflow portion 10 by the diaphragm 16, and is made of the gas of the material of the diaphragm 16. In order to prevent the gas of the pressure fluid from penetrating slightly from the pressure fluid inflow hole 10a of the pressure fluid inflow portion 10 due to the permeation characteristics and affecting the reference pressure, the internal space 14 of the reference pressure portion 14 is prevented.
a is communicated with the external space.

In the pressure switch of the embodiment constructed as described above, when the pressure of the pressure fluid flowing into the internal space 10b of the pressure fluid inflow portion 10 reaches the first predetermined value, first, the third loosening is performed. The body 26 is displaced toward the end wall 14b of the reference pressure portion 14 of the outer case 8 so that the first pressure receiving piston 20 and the second pressure receiving piston 24 move.
Move toward a.

The first push rod 28, the second push rod 30, and the third push rod 31 also move together with the first pressure receiving piston 20 and the second pressure receiving piston 24, and the third push rod 28. The protruding end of 31 is the normally open switch 36, and
The elastic contact piece 32c on the side of is pressed to turn on the normally open switch 36.

When the pressure of the pressure fluid flowing into the internal space 10b of the pressure fluid inflow portion 10 reaches a second predetermined value larger than the first predetermined value, it is supported by the first pressure receiving piston 20. The first flat spring body 18 is displaced to move the first push rod 28 to the elastic contact piece 32a of the normally closed switch 34.
Then, the normally closed switch 34 is turned off.

When the pressure of the pressure fluid flowing into the internal space 10b of the pressure fluid inflow portion 10 reaches a third predetermined value larger than the second predetermined value, it is supported by the second pressure receiving piston 24. The second Belleville spring body 22 is displaced to press the second push rod 30 against the elastic contact piece 32b of the normally open switch 36 located farther from the third Belleville spring body 26 to turn off the normally open switch 36.

Although this embodiment was a three-action pressure switch, the present invention opens and closes the electrical contacts according to the pressure, and the outer case has a pressure equalizing passage that allows the atmosphere to communicate with the internal space. It can be applied to any formed pressure switch.

Further, as the filter 40, a material other than nylon 66 suitable for the operating environment of the pressure switch and having a mesh other than about 10 micrometers can be used as long as it does not allow dust to pass through, but allows air to pass through. I can. The material of the filter 40 other than nylon 66 may be a film made of, for example, PTFE (polytetrafluoroethylene) configured to create the properties of the filter 40 described above.

Furthermore, the filter stopper 42 can be formed of a material different from that of the reference pressure portion 14,
The filter 40 can be fixed by a suitable known fixing means other than the press-fitting, and may be a detachable fixing means for enabling replacement by clogging of the filter 40.

[0035]

As described in detail above, in the pressure switch of the present invention, a pressure equalizing passage is formed which opens and closes the electrical contacts according to the pressure and allows the outer case to communicate with the atmosphere. The filter provided in the pressure equalizing passage is characterized in that the filter provided in the pressure equalizing passage serves as a reference pressure into the reference pressure side region of the internal space of the outer case through the pressure equalizing passage. It is sufficient that the introduction of atmospheric pressure and the gas slightly permeated from the pressure sensing side surface to the reference pressure side surface are discharged into the atmosphere through the pressure equalizing passage and do not affect the reference pressure in the reference pressure side area. Therefore, it is possible to sufficiently prevent the invasion of dust into the reference pressure side region of the internal space through the pressure equalizing passage.

[Brief description of drawings]

FIG. 1 is a schematic vertical sectional view of an embodiment of a pressure switch of the present invention.

2 is a top view of the embodiment of FIG. 1. FIG.

FIG. 3 is a view in which the pressure equalizing hole formed in the end wall of the closed one end of the reference pressure portion of the outer case of the embodiment of FIG. 1, the filter arranged therein, and the filter retainer are separated from each other. The figure which expands and shows in a state.

[Explanation of symbols]

8 ... Exterior case, 10 ... Pressure fluid inflow part, 10a ... Pressure fluid inflow hole, 10b ... Internal space, 12 ... Annular sealing member, 14 ... Reference pressure part, 14a ... Internal space, 14b ... End wall, 14c ... Protect Skirt, 16 ... diaphragm, 1
8 ... 1st Belleville spring body, 20 ... 1st pressure receiving piston, 22 ... 2nd Belleville spring body, 24 ... 2nd pressure receiving piston, 26 ... 3rd Belleville spring body, 28 ... 1st Push rod, 30 ... second push rod, 31 ... third push rod, 32 ... connection terminal, 32a, 32b, 3
2c ... elastic contact piece, 34 ... normally closed switch, 36 ... normally open switch, 38 ... pressure equalizing hole, 38a ... step, 40 ... filter, 4
2 ... Filter holder.

Claims (1)

[Claims] 1. A pressure equalizing passage that opens and closes an electric contact according to pressure and allows communication of the atmosphere with an internal space is formed in an outer case, and a filter is provided in the pressure equalizing passage. Pressure switch.