JPH0418187Y2 - - Google Patents

Description

[Detailed Description of the Invention] (a) Field of the Invention This invention relates to a pressure switch installed in, for example, gas pressure instruments, and more specifically relates to a pressure switch for detecting fluid pressure such as gas pressure.

(b) Background of the invention In general, a pressure switch for low pressure operation, which is designed to operate at a low pressure of about 60 millimeters of water, is operated by switching in response to the reverse deformation of the diaphragm.

For example, as shown in FIG. 5, a diaphragm 51 with a fixed peripheral edge is provided, and a rod-shaped plunger 52 is provided facing the center of the diaphragm 51, so that the diaphragm 51 responds to changes in gas pressure. The plunger 52 is slid by the reversal action of the switch 52, and a switch section interlocked with the plunger 52 is turned on and off.

However, in this case, the diaphragm 51 is made thin so that it can be reversed with a slight pressure, and the rod-shaped plunger head 5 is in contact with the center of the reversing part.
3 make point contact, local stress concentration may occur when the diaphragm 51 is initially reversed, and as shown by the imaginary line in FIG. 5, the diaphragm 5
The initial reversal operation described in No. 1 tends to occur at the peripheral edge, and as a result, the diaphragm is abnormally deformed, resulting in a reversal failure and the switch characteristics becoming unstable.

Further, as shown in FIG. 6, when the head 62 of the plunger 61 is enlarged and formed into a flat plate shape, and the plunger head 62 is configured to make surface contact with the diaphragm 63, localized contact due to point contact can be achieved. Stress concentration can be avoided, but when the diaphragm 63 is initially reversed, this initial reversal action tends to occur at the periphery, as shown by the imaginary line in FIG.
It was not possible to completely avoid the abnormal deformation of No. 3, and it was necessary to finish each part such as the plunger with high precision.

Further, as shown in FIG. 7, if the head 72 of the plunger 71 is provided to correspond to the arcuate surface of the diaphragm 73, and the plunger head 72 is configured to make spherical contact with the diaphragm 73,
Due to the unstable operation of the diaphragm 73, the switch characteristics were affected by the unstable operation.

(c) Purpose of the invention In view of the above-mentioned points, the purpose of this invention is to provide a pressure switch that can stabilize switch characteristics while using a thin diaphragm.

(d) Structure of the invention This invention consists of a diaphragm that deforms in response to changes in fluid pressure, a plunger that follows the deformation surface of the diaphragm, and a switch that performs switching operations based on the movement of the plunger. The pressure switch is characterized in that the diaphragm contacting surface of the plunger head is formed into a wide surface, and the wide surface is formed into an annular peripheral protrusion.

(e) Function of the device In this device, the diaphragm deforms in response to changes in the pressure of the fluid, and as the plunger moves to follow this deformation, the contact portions are brought into contact and separated, resulting in a switching operation. Based on this, fluid pressure changes are detected.

(f) Effects of the invention According to this invention, since the plunger receives the diaphragm on its wide surface, the entire diaphragm deforms uniformly and performs a reversal operation, and in particular, by providing an annular peripheral protrusion around the wide surface. A recess is formed in the center of the wide surface, and this recess serves as a relief when the diaphragm is reversed, and the periphery of the reversible portion is supported by a peripheral protrusion to facilitate the reversal operation at the center.

Therefore, the repeatability of the diaphragm is stabilized, and malfunctions of the switch due to poor reversal can be reliably eliminated. At the same time, local stress concentration can be eliminated, and stress can be distributed evenly around a wide surface by uniform contact, making it possible to extend the life of the diaphragm.

In addition, even if these materials are affected by heat and thermal distortion occurs due to thermal expansion, the diaphragm is connected to the diaphragm through the peripheral protrusion, resulting in a contact structure that is less susceptible to unstable operation caused by this thermal distortion. In addition, it has a corresponding structure that can absorb errors in the diaphragm contact area, and there is no need to finish these parts with high precision.
This is a pressure switch suitable for small pressure fluctuations.

(g) Example of the invention An example of the invention will be described below in detail based on the drawings.

The drawings show a pressure switch, FIGS. 1 and 2.
In the figure, this pressure switch 11 is comprised of a pressure receiving case 12 and a switch base 13 fitted into this pressure receiving case 12.

The above-mentioned pressure receiving case 12 is formed into a cylindrical body,
The upper end of this cylindrical body has a flange 14 for attaching a switch, and the opening of the cylindrical body on this flange side has a
A protective disc 16 with several pressure receiving holes 15 is attached from above, and the switch base 13 is fitted from below with it facing inside the pressure receiving case 12, and the pressure receiving holes are inserted between both cases 12 and 13. A pressure receiving chamber 17 is formed with which the pressure receiving chamber 15 communicates, and a metal diaphragm 18 is set in this pressure receiving chamber 17 so as to be freely reversible.

The diaphragm 18 has a central portion formed into an inverted portion 18a.
A stepped portion 18b is formed on the side of the outer peripheral edge, and this stepped portion 18b is sandwiched between the upper inner peripheral groove 19 of the pressure receiving case 12 and the peripheral edge of the protective disc 16, and laser welding 20 is performed from the outside thereof. Thus, the pressure receiving case 12 and the diaphragm 18 are integrated, and the sandwiched portion is sealed.

Further, a peripheral wall portion 2 is provided on the lower surface side of the pressure receiving case 12.
1 is formed, and a connecting flange 24 provided with a switch base 13 (to be described later) is fitted into an inner circumferential groove 23 at the lower end of this recess 22. are integrated, and the top surface of the fitted switch base 13 is connected to the pressure receiving case 1.
The pressure receiving chamber 17 is inserted into the recess 22 of No. 2 and is disposed opposite to the pressure receiving chamber 17 facing the diaphragm 18 described above.

The above-mentioned switch base 13 is connected to the pressure receiving case 12.
The switch base 13 is provided with a cylindrical shape that can be inserted into the recess 22 of the switch base 13, and the above-mentioned connecting flange 24, and a pair of opposing first lead terminals 25.
The second lead terminal 26 is insert-molded, the connecting flange 24 is provided protruding from the outer peripheral surface, each lead terminal 25, 26 is provided vertically from the lower surface, and a plunger guide plate 27 is mounted in the recessed portion of the upper surface. .

A vertical sliding hole 28 is provided through the center of the plunger guide plate 27, into which a plunger 29 is inserted. Further, the interior of the switch base 13 on the lower surface side of the plunger guide plate 27 has a cavity 30, and the lower end of the plunger 29 protrudes into this cavity 30, and the first lead terminal is inserted into the cavity 30. A movable contact piece 31 extending through the plunger 25 is switched in correspondence with the plunger 29.

The plunger 29 has a plunger head 29a located within the pressure receiving chamber 17, and the head 29a expands into a disk portion with a much larger diameter than the shaft portion inserted into the plunger guide plate 27. And the wide peripheral edge of the upper surface is provided to protrude upward to form an annular peripheral edge protrusion 3.
2, and the peripheral protrusion 32 is brought into contact with the inverted portion 18a of the diaphragm.

As a result, a recess 29b surrounded by the peripheral protrusion 32 is formed in the center of the plunger head 29a, and this recess 29b serves as a relief when the diaphragm is reversed, facilitating the reversal operation at the center.

Further, when the diaphragm 18 is reversed, the peripheral protrusion 32 uniformly contacts the diaphragm 18 over a wide range to disperse stress, efficiently improve the stability of contact with the diaphragm 18, and stabilize the repeatability of the diaphragm 18. There is.

By the way, the inner ends of both lead terminals 25 and 26 inserted into the switch base 13 are led out from the left and right sides of the empty chamber 30, and are connected to the first lead terminal 2.
A movable contact piece 3 equipped with a movable contact 34 is provided at the inner end of 5.
1 are connected to each other, and a fixed contact 33 is formed at the inner end of the second lead terminal 26, and the movable contact 34 and the fixed contact 33 are provided facing each other in the vertical direction within the cavity 30.

The above-mentioned movable contact piece 31 is formed of an extremely thin conductive plate spring material, and its base end is connected to the first lead terminal 25.
is connected to the inner end of the plunger 29 as an elastic fulcrum, and the free end extending from this is urged upward and extends, and this extended end is set in the pressing corresponding part 35 corresponding to the lower end of the plunger 29, The upper surface of the part is the movable contact 34.
is set to .

Then, when the plunger 29 is in the downward movement position,
The movable contact piece 31 is pushed down to separate the contacts 33 and 34, thereby cutting off the conduction between the lead terminals 25 and 26. On the other hand, when the plunger 29 is in the upward movement position,
The movable contact piece 31 moves upward to bring the contacts 33 and 34 into contact and short-circuit the lead terminals 25 and 26.

At this time, the contact position where the movable contact piece 31 approaches and separates at the middle part uses the base end as an elastic fulcrum compared to the free end, so the amount of deflection when receiving pressure is smaller, and as a result, the free end is more flexible than the free end. Also, the elastic drag at this intermediate position acts strongly, resulting in high contact pressure and stable switching characteristics.

In this way, a switch section 37 corresponding to the vertical movement of the plunger 29 is constructed in the switch base 13, and the on/off operation of this switch section 37 is controlled by a diaphragm that operates in reverse in response to changes in the pressure of gas or other fluids. Made by 18. At this time, the distance between the vertically opposing microcontacts 33 and 34 is adjusted by the adjustment screw 38 to a distance suitable for opening and closing.

In addition, a cut groove 39 for air inflow is formed at one location on the outer peripheral edge of the above-mentioned connecting flange 24. By providing this cut groove 39, the air can enter the outer circumference of the switch base 13 and the groove. An atmospheric pressure passage 40 is formed which communicates with the outer circumferential portion of the diaphragm surface of the pressure receiving case 12 through the space between the bottom part 22 and the upper surface of the diaphragm 18. The opposite lower surface side is set to the atmospheric pressure side that communicates with the atmospheric pressure passage 40, allowing the diaphragm 18 to deform.

In the pressure switch configured in this way, when the inverted portion 18a of the diaphragm 18 is deformed into an arcuate shape due to fluid pressure, the plunger 29 pressed against this deformed surface pushes down the movable contact piece 31 and deforms both sides. When the contacts 33 and 34 are separated, a constant fluid pressure load is detected.

When the fluid pressure drops, the inverted portion 18a of the diaphragm 18 inverts back to its original state,
Based on this, the plunger 29 is pushed upward by the biasing pressure of the movable contact piece 31, and the movable contact 34 formed on the movable contact piece 31 is brought into contact with the upper fixed contact 33 and conductive, thereby signaling a drop in fluid pressure. Output.

In this case, as shown in FIG.
9 receives the diaphragm 18 on its wide surface, the entire diaphragm 18 deforms uniformly and reverses, and as shown in FIG.
This facilitates the reversal operation at the center.

Therefore, the repeatability of the diaphragm 18 is stabilized, and switch malfunctions due to inversion failure can be reliably eliminated. At the same time, local stress concentration can be eliminated, and stress can be distributed evenly around a wide surface by uniform contact, thereby reliably extending the life of the diaphragm.

In addition, even if these materials are affected by heat and thermal distortion occurs due to thermal expansion, the diaphragm 18 is connected to the diaphragm 18 by the peripheral protrusion 32, so the contact structure is not easily affected by unstable operation based on this thermal distortion. In addition, it has a corresponding structure that can absorb errors in the diaphragm contact area, and without having to finish these parts with high precision, it becomes a pressure switch suitable for minute pressure fluctuations.

[Brief explanation of drawings]

The drawings show one embodiment of this invention, in which Fig. 1 is a longitudinal cross-sectional view of the pressure switch, Fig. 2 is an exploded perspective view of the pressure switch, Figs. 3 and 4 are explanatory diagrams of the operation of the plunger, and Fig. 5. 7 is an explanatory diagram of the operation of a conventional plunger. DESCRIPTION OF SYMBOLS 11...Pressure switch, 18...Diaphragm, 29...Plunger, 29a...Plunger head, 32...Peripheral projection, 37...Switch portion.

Claims (1)

[Claims for Utility Model Registration] A diaphragm that deforms in response to changes in fluid pressure, a plunger that contacts and moves following the deformation surface of the diaphragm, and a switch that performs a switching operation based on the movement of the plunger. , A pressure switch in which the diaphragm contact surface of the plunger head is formed into a wide surface, and this wide surface is formed into an annular peripheral protrusion.