JPS642357Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a pressure switch that includes a diaphragm that detects pressure and is displaced, and a switch that responds to the displacement of the diaphragm.

[Prior art]

In a pressure switch, a diaphragm is provided to partition the hollow part of the switch body into a first and second chamber, and the diaphragm is displaced in response to pressure from a pressure source acting on the first chamber to open and close the switch. are doing. Since the volume of the second chamber changes depending on the displacement of the diaphragm, a ventilation path is provided to communicate the second chamber with the outside.

However, if the switch is used in a place where raindrops etc. may enter while the switch is running, such as the engine room of a car, moisture may enter the second room through the ventilation passage and corrode the contact parts inside the switch. There is a problem of shortened lifespan, and in order to solve this problem, the applicant applied pressure to swage the breathable and water-repellent film applied to cover the open end of the vent hole. I am applying for a switch. However, in this case, when the diaphragm is displaced and the volume of the second chamber changes, the pressure in the second chamber temporarily becomes different from atmospheric pressure due to the ventilation resistance of the film, so the switch cannot operate. There is a problem in that there is a time delay compared to the pressure change of the pressure source.

[Purpose of invention]

This idea was made in view of the above circumstances.
The purpose is to provide a pressure switch which can operate without any time delay in response to changes in the pressure of a pressure source, and which can prevent moisture from entering the switch body.

[Summary of the idea]

The present invention provides a first chamber and a second chamber separated by a diaphragm in a switch case, communicates the first chamber with a pressure source, and communicates the second chamber with the switch case. It is characterized in that an air reservoir chamber is integrally provided, and the air reservoir chamber is communicated with the atmosphere through an air permeable member.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings. 1 is a switch case, which consists of a container body 3 having a flange portion 2 on its end face;
It consists of a lid member 5 having a flange portion 4 that comes into contact with the flange portion 4, and is integrated by engaging the engaging claw 3a with the flange portion 4. 6 and 6' are diaphragms whose peripheral edges are sandwiched between the flange parts 2 and 4;
Pressure chambers 7, 7' as first chambers facing the diaphragms 6, 6' are formed in the lid member 5, and switch chambers 8, 8' as second chambers facing the diaphragms 6, 6' are formed in the lid member 5. It is formed. Communication pipes 9 and 9' communicate with the pressure chambers 7 and 7', and these communicate with different pressure sources through pipes (not shown). 10, 10' are pressure chambers 7,
7' are screw holes formed to communicate with each other,
Adjustment screws 11 and 11' are screwed together. 12,
Reference numeral 12' denotes a spring receiver formed in a cylindrical shape with a bottom, the inner bottom part of which is applied from inside the container body 3 to the end face of the adjusting screws 11, 11', and the flange part 1 curved on the outer periphery.
One end surface of the springs 13, 13' is in contact with 2a, 12'a. Reference numerals 14 and 14' designate center disks molded from plastic, with annular recesses 14a and 1 formed on one end surface of the center disks.
The other end surfaces of the springs 13, 13' are placed inside the spring 4'a, and the other end surfaces of the center disks 14, 14' are brought into contact with one end surface of the diaphragms 6, 6'. Reference numeral 15 denotes a holding plate held between the flanges 2 and 4 so as to press down the peripheral edges of the diaphragms 6 and 6', and 16 a packing held between the holding plate 15 and the flange 4. 17,
17' is located in the switch chambers 8, 8' and is attached to the presser plate 15.
Fixed contacts 18 and 18' are movable contacts that are brought into contact with the other end surfaces of the diaphragms 6 and 6' so as to face the fixed contacts 17 and 17'. This positioning is achieved by fitting the central holes 19, 19' into convex portions 6a, 6'a projecting from the center of the diaphragms 6, 6'. Fixed contacts 17, 17' and movable contacts 18, 1
8' constitute switches 20, 20'.
21, 21' connect the bottom wall of the lid member 5 with an O-ring 22,
22', and the end of this terminal on the diaphragm 6, 6' side is provided with receivers 23, 2.
3' is caulked, and this receiver 23,
Springs 24, 24' are inserted between 23' and the movable contacts 18, 18' to bias the movable contacts 18, 18' in the opposite direction of arrow A, and as shown by the solid line in the drawing, the pressure chamber 7 , 7' are at the same pressure as atmospheric pressure, the movable contact 18 and the fixed contact 17 are separated and the switch 20 is in the open state, and the movable contact 18' and the fixed contact 17' are in contact and the switch 20' is in the open state. is in a closed state. Terminal plates 25 and 25' are caulked to the outwardly projecting ends of the lid member 5.

Now, 26 is an air reservoir chamber that is formed integrally with the lid member 5 and whose one end face is closed by the flange portion 2 of the vessel body 3, and this is connected to the switch chambers 8, 8' and the communication hole 26a
26b, and this air reservoir chamber 2
6 has an internal volume V ₂ that is sufficiently larger than the internal volume V ₁ of the switch chambers 8 and 8'. Reference numeral 27 denotes a vent hole formed in the flange portion 2 of the container body 3 so as to communicate the air reservoir chamber 26 with the outside, and a hole 15a communicating with the inner end of the vent hole 27 is provided in the holding plate 15. ing. Reference numeral 28 denotes a film serving as an air permeable member whose peripheral edge is clamped between the holding plate 15 and the container body 3 so as to cover the inner end of the ventilation hole 27. (trade name: Gore-Tex), etc., and has breathability and water repellency.
Although it is preferable that the film 28 has water repellency, it is also possible to use a filter made of ordinary sponge or felt, since it has a certain degree of waterproofing effect.

Next, the operation of the above configuration will be explained using an example in which the pressure of the pressure source communicating with the pressure chamber 7 is changed. That is, in the state shown by the solid line in the drawing in which the pressure of the pressure source is the same as the atmospheric pressure _P0 , the movable contact 18 is separated from the fixed contact 17 and the switch 20 is in an open state.

Next, when the pressure of the pressure source decreases and the pressure inside the pressure chamber 7 reaches _P1 , the diaphragm 6 switches the switch chamber 8.
Receiving the biasing force of the spring 24 from the side, it moves counter-arrow A.
The movable contact 18 contacts the fixed contact 17, the switch 20 is closed, and the terminal plate 25 is moved to the position shown by the two-dot chain line.
Receiver 23, spring 24, movable contact 1
8. A state of conduction is established with the container body 3 via the fixed contact 17 and the holding plate 15.

On the other hand, since the internal volume V ₁ of the switch chamber 8 increases by ΔV due to the displacement of the diaphragm 6, the air from the outside communicates with the switch chamber 8 through the film 28 covering the ventilation hole 27. 26. By the way, film 28
has ventilation resistance, so in the conventional type without the air reservoir chamber 26, when the volume of the switch chamber 8 suddenly changes, outside air cannot immediately flow into the switch chamber 8, and therefore the switch The pressure inside the chamber 8 temporarily becomes P ₀ V ₁ /V ₁ +△V, which is lower than the atmospheric pressure (negative pressure) and inhibits the movement of the diaphragm 6 in the opposite direction of arrow A, causing the diaphragm 6, that is, the movable contact There was a drawback that the displacement of the pressure chamber 18 caused a time delay with respect to the pressure change within the pressure chamber 7.

However, in the above embodiment, the air reservoir chamber 26 (volume V ₂ ) communicates with the switch chamber 8 (volume V ₁ ).
≫V ₁ ) is provided, and this air chamber 26 is connected to the film 2
Since the atmosphere was communicated through switch chamber 8,
The substantial volume (V ₁ +V ₂ ) of the can be increased. Therefore, the pressure immediately after the displacement of the diaphragm 6 becomes (V ₁ +V ₂ /V ₁ +V ₂ +△VP ₀ ), which can be made closer to atmospheric pressure P ₀ than in the past, and there is ventilation resistance in the film 28. Regardless of the situation, the time during which the inside of the switch chamber 8 is under negative pressure can be reduced as much as possible, and the diaphragm 6 and the movable contact 18 can be displaced in immediate response to changes in the pressure inside the pressure chamber 7 without any time delay.

Further, since the film 28 has water repellency, even if the switch case 1 is used in a state where it is exposed to water or raindrops, moisture can be prevented from entering the switch chamber 8. Further, when the pressure of the pressure source communicating with the pressure chamber 7' is changed, the diaphragm 6 moves the spring 2 in the same manner as described above in response to the pressure change.
Reverse arrow A without any time delay due to the bias of 4'
direction, and the switch 20' is opened.

It should be noted that the present invention is not limited to the above-mentioned embodiments, but can be modified in various ways without departing from the gist, such as being applicable to a pressure switch in which positive pressure acts on the pressure chambers 7, 7'.

[Effect of idea]

As is clear from the above description, the present invention provides a first chamber and a second chamber partitioned by a diaphragm in a switch case, communicates the first chamber with a pressure source, and the second switch case.
An air reservoir chamber that communicates with the chamber of This has the effect of being able to operate and preventing moisture from entering the switch body.

[Brief explanation of the drawing]

The drawing is a longitudinal sectional view showing an embodiment of the present invention. In the figure, 1 is a switch case, 6, 6' is a diaphragm, 7, 7' is a pressure chamber (first chamber), 8, 8'
20 and 20' are switches, 26 is an air reservoir chamber, and 28 is a film (breathable member).

Claims (1)

[Scope of utility model registration request] A first chamber and a second chamber are provided in the switch case by being partitioned by a diaphragm,
The first chamber is connected to a pressure source, a diaphragm is displaced according to pressure changes of the pressure source, and a switch is operated according to the displacement of the diaphragm. A pressure switch characterized in that an air reservoir chamber communicating with the second chamber is integrally provided in the switch case.