JPH0117070Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Object 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) Conventionally, pressure switches of this type that utilize the displacement of a diaphragm have been invented (devised) as shown in Japanese Patent Application Laid-open No. 51-87084 or Japanese Utility Model Application Publication No. 59-77747. In these devices, a filter having air permeability and water repellency is provided in a communication hole leading to a chamber in contact with one surface of the diaphragm to prevent moisture from entering the chamber.

(Problem to be solved by the invention) In the above-mentioned conventional filters, the filters are extremely slippery due to their water repellency, so all of them do not slip during assembly or during use. If the filter were to shift from the ventilation hole, moisture would enter and leave the chamber along with the air that is in contact with one side of the diaphragm, so it should not be placed in the chamber. There was a risk that the contact points of the switch or the spring for setting the pressure would corrode, resulting in poor contact of the switch, or that the pressure at which the diaphragm was displaced would be affected, resulting in inaccurate operation.

Therefore, the purpose of the present invention is to securely attach the filter to the ventilation hole and prevent it from shifting from the ventilation hole, and to reliably prevent moisture from entering the chamber that is in contact with one side of the diaphragm. The objective is to provide a pressure switch that can operate accurately.

[Structure of the invention] (Means for solving the problem) The invention has a switch chamber containing a diaphragm that detects pressure and displaces, and a switch that responds to the displacement of this diaphragm, and has a switch chamber that is connected to the inside and outside of the switch chamber. In the device that forms a communicating ventilation hole and covers the ventilation hole with a porous filter having air permeability and water repellency, the ventilation hole is provided with a bottom part surrounding the ventilation hole, and an annular presser foot corresponding to the bottom part. The filter is characterized in that a rough surface portion is formed on at least one side of the filter body, and the peripheral portion of the filter is held between the bottom surface portion and the presser body.

(Function) According to the above-mentioned means, the filter can be securely attached to the ventilation hole and can be prevented from slipping from the ventilation hole during assembly or use, so that the filter can be securely attached to the ventilation hole and can be prevented from shifting from the ventilation hole. Since moisture is reliably prevented from entering the switch and the pressure setting spring is not corroded, accurate operation can be achieved.

(Example) The following is an example of the present invention shown in Figures 1 and 2.
This will be explained with reference to the figures. 1 is the switch body, and the metal body 2 has a vacuum chamber 3.
It has a tube connection port 4 that communicates with the tube. 5
is a plastic insulator caulked to the body 2, and the peripheral edge of a diaphragm 6 that closes one side of the vacuum chamber 3 is sandwiched between this and the body 2. A switch chamber 7 corresponding to the diaphragm 6 is recessed in the insulator 5. Reference numerals 8 and 9 indicate a movable contact and an inner plate that sandwich the center of the diaphragm 6, and a shaft portion 8a protruding from the movable contact 8 passes through a through hole 6a at the center of the diaphragm 6 and caulks the inner plate 9 to the tip. The diaphragm 6 is fixed to the inner plate 9 in the vacuum chamber 3, and the diaphragm 6 is moved through the inner plate 9 in the direction indicated by the arrow A.
A coil spring 10 is provided that biases in the direction. Reference numeral 11 denotes a through hole that passes through the insulator 5 and communicates with the inside of the switch chamber 7, and an O-ring 13 is inserted here.
A metal cylindrical vent body 12 is fitted through the hole. 14 is a fixed contact located in the switch chamber 7 and fixed to the vent body 12 by caulking. This and the movable contact 8 constitute a switch 15, and when atmospheric pressure is acting on the vacuum chamber 3, the coil The movable contact 8 is in contact with the fixed contact 14 due to the spring force of the spring 10. Reference numeral 16 denotes a substantially L-shaped connector terminal, through which the above-mentioned vent body 12 passes through the mounting hole 16a, and is held between the large diameter portion 17 provided at the end of the vent body 12 and the insulator 5. The insulator 5
is fixed to. Reference numeral 18 denotes a vent hole passing through the vent body 12, and an annular recess 19 surrounding the open end of the vent hole 18 is formed in the large diameter portion 17. The bottom surface of the annular recess 19 has minute irregularities on the surface to form an annular rough surface part 20. 21
is a breathable and water-repellent filter made of, for example, a porous Teflon film (trade name: Gore-Tex) made of tetrafluoroethylene, etc., and is disposed on the end face of the large diameter portion 17 of the vent body 12 to allow the air to pass through. Stomata 1
It covers 8. Reference numeral 22 denotes an annular presser body in which a rough surface portion 23 substantially similar to the rough surface portion 20 is formed in a portion corresponding to the rough surface portion 20, and the surrounding portion of the above-mentioned filter 21 corresponds to the rough surface portion 20 formed on the vent body 12. It is held between the rough surface part 23 of the presser body 22. and,
The presser body 22 is fixed to the large diameter portion 17 of the vent body 12 by caulking the tip of the large diameter portion 17 . In addition, 24 is a connector guide that is integrally molded and protrudes from the insulator 5 and connects the connector terminal 16.
This is for guiding a connector (not shown) connected to the connector.

A tube communicating with a vacuum source is connected to the tube connection port 4, and the body 2 is fixed to a vehicle body or the like and grounded. Therefore, when the inside of the vacuum chamber 3 is at atmospheric pressure and the movable contact 8 and the fixed contact 14 are in contact, the connector terminal 16 connects the vent body 12, the fixed contact 14, the movable contact 8, the inner plate 9, and the coil spring 10. In turn, it is electrically connected to the body 2 and grounded. On the other hand, when the inside of the vacuum chamber 3 communicating with the vacuum source reaches a predetermined negative pressure value, the diaphragm 6 becomes displaced in the opposite direction of arrow A against the coil spring 10, and the movable contact 8 is separated from the fixed contact 14. Then, the switch 15 becomes open. Then, when the volume of the switch chamber 7 changes according to the displacement of the diaphragm 6, air corresponding to the change in volume flows into and out of the switch chamber 7 through the ventilation hole 18 and the filter 21, and the air pressure inside the switch chamber 7 increases. is always equal to atmospheric pressure. Therefore, the negative pressure value in the vacuum chamber 3 and the displacement of the diaphragm 6 are accurately proportional, and the switch 15 is opened and closed at the set negative pressure value without causing any delay in operation.

In the above configuration, the vent body 12 is provided with the rough surface portion 20 at the bottom of the annular recess 19 surrounding the vent hole 18, and the outer peripheral portion of the filter 21 that covers the vent hole 18 is provided on the rough surface portion 20 and the presser body 22. Since the film is held between the rough surface part 23 and the rough surface part 23, the surface is smooth and slippery, such as a porous Teflon film made of tetrafluoroethylene, and it does not have the repulsive force of rubber, so it can be compressed. The filter 21, which generates almost no resistance, can be reliably held so as to cover the ventilation hole 18.

That is, if the rough surface portions 20 and 23 are not provided, even if the filter 21 is strongly clamped and compressed, the filter 21
Since it does not have a repulsive force, it easily comes off, but since the periphery of the filter 21 is sandwiched between the rough surface parts 20 and 23 as described above, the filter 21
can be reliably held in the attached state. Then, the filter 21 securely covers the ventilation hole 18 and the switch chamber 7 is opened.
This prevents moisture from entering the filter, allowing the switch 15 to be operated accurately, and furthermore, preventing the surface of the filter 21 from protruding beyond the presser body 22 and causing water droplets to remain attached to the surface. ,
The pressure inside the switch chamber 7 is always equal to atmospheric pressure, and the switch 15 always operates accurately at the set pressure.

In addition, as shown in FIGS. 3 and 4, the annular recess 1
The rough surface 20 of 9 may be provided with a plurality of grooves 20a instead of the fine unevenness, and in this case, instead of the connector terminal 16, a lead wire connection terminal 25 shown in FIG. 5 and the large diameter portion 17 of the vent body 12. Further, as shown in FIG. 5, the same effect can be obtained by forming a plurality of grooves 23a on the rough surface 23 of the presser body 22 instead of the fine unevenness.

Further, by forming a rough surface portion only on either the bottom surface of the annular recess 19 or the presser body 22, the filter 2
It is also possible to clamp and hold the peripheral portion of 1.

[Effects of the invention] As is clear from the above description, the present invention has a switch chamber containing a diaphragm that detects pressure and displaces, and a switch that responds to the displacement of this diaphragm, and communicates the inside and outside of the switch chamber. A vent hole is formed, and the vent hole is covered with a porous filter having air permeability and water repellency. A rough surface portion is formed on at least one of the bottom surface portion and the presser body, and the peripheral portion of the filter is held between the bottom surface portion and the presser body, so that the filter can be securely attached to the ventilation hole during assembly. Alternatively, since it can be prevented from shifting from the vent hole during use, it is reliably prevented that moisture enters the chamber that is in contact with one side of the diaphragm through the vent hole, and the switch or pressure setting spring is corroded. This has the excellent effect of ensuring accurate movement because no errors occur.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the present invention, with Figure 1 being a longitudinal sectional view, Figure 2 being an exploded perspective view of the main parts, and Figures 3 and 4 being an embodiment of the present invention. Fig. 3 is an enlarged sectional view of the main part, Fig. 4 is a partially cutaway side view of the main part, and Fig. 5 is a diagram showing a different embodiment of the present invention. This is a diagram equivalent to Figure 3. In the drawing, 1 is the switch body, 2 is the body, 3 is the vacuum chamber, 5 is the insulator, 6 is the diaphragm, 7 is the switch chamber, 8 is the movable contact,
9 is an inner plate, 10 is a coil spring, 12 is a vent body, 14 is a fixed contact, 15 is a switch, 18 is a vent hole, 20 is a rough surface part, 21 is a filter, 22 is a presser body, 23 is a rough surface part, 20a and 2
3a is a grooved portion.

Claims (1)

[Scope of utility model registration request] It has a switch chamber with a built-in diaphragm that detects pressure and displaces, and a switch that responds to the displacement of this diaphragm, and a ventilation hole that communicates between the inside and outside of the switch chamber. A rough surface portion is formed on at least one of a bottom portion provided to surround the ventilation hole and an annular presser body corresponding to the bottom portion, and the bottom portion and the presser body A pressure switch characterized in that a peripheral portion of the filter is held and held by the above-mentioned filters.