JPH0932087A - Vacuum valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the gas-liquid ratio of waste water and air by turning off a detection switch by a plunger to stop the introduction of vacuum force into a pressure control chamber and then opening a vacuum release passage for releasing the vacuum force in the pressure control chamber by a plunger. SOLUTION: A controller part 27 comprises a three-way valve 71 for switching between a vacuum passage and an air passage to a valve operating chamber 25, a liquid level detecting diaphragm 60 operated in response to the liquid level of a tank, a pressure control chamber 83 for applying the vacuum force to a valve 1 in such a manner that the valve 71 connects the vacuum passage to the valve operating chamber 25, a detection switch 68 disposed in the control chamber 83 to introduce the vacuum force into the control chamber 83, and a plunger 65 which is directly driven by the diaphragm 60, and inserted in the control chamber 83 to turn on and off the switch 68. When the switch 68 is turned on by the plunger 65, the plunger 65 is brought into contact with a seal 67 of a vacuum release passage 65A to close the passage 65A, and when the switch 68 is turned off, the plunger 65 is separated from the seal 67 to open the passage 65A.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a vacuum valve suitable for use in a vacuum sewer system or the like.

[0002]

2. Description of the Related Art As described in Japanese Patent Laid-Open No. 3-43527, a vacuum sewer system is designed to allow wastewater discharged from homes, factories, etc. to flow into a wastewater tank of a vacuum valve unit from a naturally flowing wastewater inflow pipe. The sewage collected in the sewage tank is collected by the vacuum sewage pipe in the water collection tank, and then sent to a sewage treatment plant by a pressure pump.

A vacuum valve is installed in the sewage tank, and the connection between the suction pipe rising from the bottom of the sewage tank and the vacuum sewer pipe communicating with the vacuum source can be opened and closed by this vacuum valve. I am trying. Then, when the water level in the dirty water tank rises above a certain level, the vacuum valve is opened, the vacuum pressure of the vacuum sewer pipe is exerted on the suction pipe, and the atmospheric pressure that acts on the water surface of the dirty water tank to pressurize the dirty water is set. The sewage in the sewage tank is sent to the water collection tank via the vacuum sewer pipe by the pressure difference from the vacuum pressure applied to the suction pipe.

At this time, the controller part of the vacuum valve has a liquid level detection diaphragm which operates in response to a predetermined liquid level in the dirty water tank and a three-way valve which switches between opening and closing of the vacuum valve. By activating the detection valve via the plunger by movement, a vacuum force is introduced from the vacuum sewer pipe to the pressure control chamber, and the three-way valve is activated by this vacuum force. The vacuum force introduced to the pressure control chamber is released to the atmosphere by the needle valve.

That is, in the prior art, it was general to provide a bypass path connecting the lower atmosphere chamber of the liquid level detection diaphragm and the pressure control chamber, and to provide a needle valve for adjusting the amount of air passing through the bypass path. The operation of the vacuum valve uses the pressure difference between the vacuum pressure and the atmospheric pressure as its starting force, and the air conducted through this bypass path is a necessary condition for the vacuum valve to move to the closing operation. By adjusting the air volume, it was possible to control the opening time of the vacuum valve. In the conventional vacuum valve, the position of the liquid level detection pipe is adjusted so that the amount of water sucked from the suction pipe is about 40 liters, and it is the volume ratio of sewage and air sucked into the vacuum sewer pipe by needle valve adjustment. Gas-liquid ratio is 3:
The standard setting is 1.

[0006]

However, the prior art has the following problems. The conventional control method adjusts the gas-liquid ratio by adjusting the needle valve and determining the opening time of the vacuum valve under the condition that the vacuum pressure applied to the vacuum valve is always constant. In this state, if the vacuum pressure inside the vacuum sewer that communicates with the vacuum valve is significantly lower than when it was set (the suction force of the sewage is reduced, the rate of sewage water level drop is also reduced), or it is increased in a short time. When a large amount of sewage flows in, a large amount of sewage will continue to flow in even when sewage is sucked in, so the sewage water level will drop slowly, and the amount of air suctioned will be reduced or not sucked at all during the set time vacuum valve opening time. There are cases. Such a decrease in the gas-liquid ratio makes the system unstable and causes water hammer and the like. In addition, since the needle valve communication hole is very small, there is a possibility that the opening time of the vacuum valve will change due to the accumulation of fine dust and the adhesion or blockage of liquid such as dew condensation water. Will be needed.

The external air flowing in through the needle valve communication hole flows in before the detection valve is closed, that is, even during the opening operation of the vacuum valve, so that it always flows into the pressure control chamber. Therefore, when the vacuum pressure inside the vacuum sewer pipe that communicates with the vacuum valve drops significantly, the drop in vacuum pressure inside the pressure control chamber due to this inflowing air has an effect,
The opening operation of the vacuum valve may be abnormal.

It is an object of the present invention to improve the gas-liquid ratio of sewage and air sucked into a vacuum sewer pipe, and to enable the vacuum valve to normally open even when the vacuum pressure of the vacuum sewer pipe is low. And

[0009]

According to a first aspect of the present invention, a connecting portion between a suction pipe communicating with a tank and a vacuum sewer pipe communicating with a vacuum source can be opened and closed, and the connecting portion is opened and closed. Valve body, a valve working chamber that accommodates a plunger connected to the valve body, a closing force applying unit that is built in the valve working chamber and applies a closing force to the valve body, and a vacuum pressure is applied to the valve working chamber. And a controller unit for applying an opening force to the valve body, the controller unit including a three-way valve capable of switching and connecting the vacuum passage and the atmosphere passage to the valve working chamber, A liquid level detection diaphragm that operates in response to the liquid level in the tank, a pressure control chamber that applies a vacuum force to the three-way valve so that the three-way valve connects the vacuum passage to the valve working chamber, and a pressure control chamber A detection switch that is installed to enable the introduction of vacuum force into the pressure control chamber And a plunger that is directly driven by the liquid level detection diaphragm and is inserted into the pressure control chamber to turn on / off the detection switch, and the plunger turns off the detection switch to connect to the pressure control chamber. After stopping the introduction of the vacuum force, the plunger opens the vacuum release passage for releasing the vacuum force in the pressure control chamber.

According to a second aspect of the present invention, in addition to the first aspect of the present invention, the plunger is provided with a seal in a vacuum release passage between the lower atmosphere chamber of the liquid level detecting diaphragm and the pressure control chamber. When the detection switch by the plunger is turned on, the plunger is brought into contact with the seal of the vacuum release passage to close the vacuum release passage, and after the detection switch by the plunger is turned off, pressure from the liquid level detection tube is not applied. When the atmospheric pressure is reached, the plunger is separated from the seal of the vacuum release passage to open the vacuum release passage.

According to a third aspect of the present invention, in addition to the first or second aspect of the present invention, the pipe end of the liquid level detection pipe for detecting the liquid level of the tank is replaced with the pipe end of the suction pipe. It is set at the same level or lower.

That is, according to the present invention, the following operational effects are obtained. The vacuum valve remains open as long as the plunger closes the vacuum release passage. When the pressure acting on the liquid level detection diaphragm becomes atmospheric pressure, the vacuum release passage is opened. This is when the liquid pressure is no longer applied to the liquid level detection pipe (when the sewage is rising, the liquid pressure acts on the diaphragm as the pressure inside the liquid level detection pipe), so when the liquid level reaches the end of the liquid level detection pipe. Air flows in through the vacuum release passage where the plunger is opened, and the vacuum valve closes. Here, by setting the pipe end of the liquid level detection pipe to the same level as or slightly lower than the pipe end of the suction pipe, the time required for switching the three-way valve and closing the valve body of the vacuum valve body (always almost constant). You can think of it as time), but you will always inhale air. As a result, when the pressure of the vacuum sewer that communicates with the vacuum valve is the set pressure, the gas-liquid ratio of sewage and air will of course be the set value, but the vacuum pressure will drop significantly below the set pressure. Even when the vacuum valve is operable (at a vacuum pressure at which the vacuum valve can operate), the vacuum valve always sucks air, so water blocks are less likely to occur compared to conventional products.

By eliminating the needle valve conduction function, external air does not flow into the pressure control chamber during the vacuum valve opening operation, so that the vacuum valve can be fully opened even under a vacuum pressure lower than the conventional one. .

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 is a schematic diagram showing a vacuum type waste water collecting device, FIG. 2 is a schematic diagram showing a vacuum valve, FIG. 3 is a sectional view showing a controller part of the vacuum valve, and FIG. FIG. 5 is a schematic diagram showing the plunger, FIG. 5 is a schematic diagram showing the detection valve on state by the plunger, FIG. 7 is a schematic diagram showing the detection valve off state by the plunger, and FIG. 9 is a schematic diagram showing the operation of the apparatus, FIG. 9 is a schematic diagram showing the operating principle of the vacuum valve, and FIG. 10 is a schematic diagram showing the operating principle of the vacuum valve.

(First Embodiment) Vacuum type waste water collecting apparatus 10
As shown in FIG. 1, the sewage tank 11 is connected to the sewage inflow pipe 12
And a suction pipe 13 communicating with the tank 11.
And a vacuum valve 15 that can open and close a communication part between the vacuum sewer pipe 14 communicating with the vacuum source.

That is, the sewage discharged from each home or the like flows into the tank 11 through the natural-flow-type sewage inflow pipe 12. Then, when the dirty water is collected in the tank, the vacuum valve 15 is opened, and the dirty water in the tank 11 is sucked through the suction pipe 13. Then, the sewage is sucked into the vacuum sewer pipe 14 through the vacuum valve 15, collected in the water collecting tank on the vacuum pump, and then sent to the sewage treatment plant by the pressure pump.

The vacuum valve 15 connects the first and second housings 21 and 22 to the band clamp 2 as shown in FIGS.
3 and includes a valve body 24, a valve operating chamber 25, a spring 26, and a controller 27.

The valve body 24 opens and closes a connecting passage 28 which constitutes a connecting portion between the suction pipe 13 and the vacuum sewer pipe 14.

The valve working chamber 25 includes a valve valve body 24 and a valve rod 29.
The cup-shaped plunger 30 connected via the is slidably accommodated.

The spring 26 is the plunger 30 of the valve working chamber 25.
It is housed in the upper chamber and exerts a spring force on the plunger 30 to apply a closing force to the valve element 24. In the chamber below the plunger 30 of the valve working chamber 25, the atmosphere communication pipe 43 is connected to the hose 4
It is connected via 6 and is at atmospheric pressure.

The controller unit 27 applies a vacuum pressure to the upper chamber of the valve operating chamber 25 when the level of dirty water in the tank 11 rises, and pulls up the plunger 30 by the differential pressure between the upper and lower chambers (the lower chamber is atmospheric pressure). Then, an opening force is applied to the valve valve body 24 to open the vacuum valve 15 and bring the vacuum sewer pipe 14 into conduction with the suction pipe 13.

The controller unit 27 is constructed as follows. The controller unit 27, as shown in FIG.
The fifth cylinder-shaped cases 51 to 55 are integrally formed with bolts. Normally, the fourth case 54 is integrated with the second housing 22 of the vacuum valve 15 by the band clamp 36.

The controller section 27 has a liquid level detection pipe connection port 56 to which a liquid level detection pipe 37 communicating with the tank 11 is connected via a hose 38. The liquid level detection pipe connection port 56 is connected to the first case 51 via a vibration damping prevention diaphragm 59. A small through hole is provided in the diaphragm 59 to transmit pressure, and the outer peripheral portion of the diaphragm 59 is not fixed.
The air from the lower side can also pass around the diaphragm 59.

The controller section 27 has a vacuum pressure connection port 57 to which the vacuum sewer pipe 14 is connected via a hose 41.
Is provided in the third case 53.

Further, the controller section 27 has an atmospheric pressure connection port 58 to which the atmosphere communication pipe 43 is connected via a hose 44.
Is provided in the third case 53.

The first case 51 and the second case 52 are connected via a liquid level detection diaphragm 60. A push button composed of a plunger 61, a spring 63, and an elastic cover 62 is provided on the upper part of the first case 51 so that the liquid level detection diaphragm 60 can be manually displaced. The second case 52 has a plunger 65 under the diaphragm 60.
However, it is provided so as to reach the detection valve 68 (detection switch) installed in the third case 53. The chamber 83 of the plunger 65 is arranged to prevent air from leaking into the upper chamber 83 as a pressure control chamber formed by the second case 52 and the third case 53.
A shaft seal 67 such as a U packing or an O ring is provided around the insertion portion.

The detection valve 68 is disposed in the room 83 and is turned on / off by the plunger 65.
A vacuum force can be introduced inside. That is, the third case 53 has the passage 57A communicating with the vacuum pressure connection port 57, and the detection valve 68 can open and close the opening (vacuum port) of the passage 57A to the chamber 83. Reference numeral 66 is a return spring of the plunger 65.

Valve seats 72 and 73 are provided in the fourth case 54 and the fifth case 55, and an upper chamber 85 of the fourth case 54 is provided.
Communicates with the atmosphere through the passage 92, and the fifth case 5
The lower chamber 87 of No. 5 communicates with the vacuum sewer pipe through a passage 91. The chamber 86 formed by the lower part of the fourth case 54 and the upper part of the fifth case 55 has a passage 96 in the working chamber 25 of the vacuum valve body.
Through. The valve body 71 provided between the two valve seats 72 and 73 plays a role as a three-way valve so as to guide either the atmosphere or the vacuum to the chamber 86 by sliding up and down. The valve body 71 is connected to a three-way valve diaphragm 70 provided between the third case 53 and the fourth case 54, and a compression spring 69 is provided above the diaphragm 70 and is pressed against the valve seat 73 of the fifth case 55. Has been. Third
A partition is provided in the case 53, but the communication port 8 is partially provided in the case 53.
8 is provided so that the vacuum pressure applied to the upper chamber 83 when the detection valve 68 is activated and opened is communicated to the lower chamber 84.

Further, as shown in FIG. 4, an insertion passage for the plunger 65 between the upper chamber 83 (pressure control chamber) of the third case 53 and the liquid level detection diaphragm lower atmosphere chamber 82 is formed as a vacuum release passage 65A. The plunger 65 is inserted into the vacuum release passage 65A via the above-mentioned seal 67. At this time, the plunger 65 has a tapered shape or a grooved shape as shown in FIG.
When the detection valve 68 is turned on, the plunger 65 is brought into contact with the seal 67 of the vacuum release passage 65A so as to contact the vacuum release passage 6A.
5A is closed (FIG. 6), and (b) the plunger 65 is connected to the vacuum release passage 65A when the detection valve 68 is turned off by the plunger 65.
The vacuum release passage 65A is opened apart from the seal 67 (see FIG. 7). The plunger 65 has an R (roundness) at a corner portion which is a contact point with the seal 67 to improve the durability of the seal 67.

A needle valve 74 with a diaphragm as a vacuum force release valve is provided in a passage 93 which communicates the inside and the outside of the upper chamber 83 (pressure control chamber) of the third case 53, and passes through the needle valve 74. The atmosphere is gradually coming in. However, in the present invention, the needle valve 74 is fully closed to freeze its function. Should the plunger 65
When an abnormality occurs in the vacuum release passage 65A, the needle valve 74 is opened to forcefully introduce air into the air 83.

Further, in the vacuum type waste water collecting device 10, the pipe end position of the liquid level detecting pipe 37 is set to the same level as or slightly lower than the pipe end position of the suction pipe 13.

The vacuum type waste water collecting device 10 operates as follows (FIGS. 8 to 10). When the liquid level of the dirty water in the tank 11 rises, the air pressure of the liquid level detection diaphragm upper chamber 81 rises through the liquid level detection pipe 37, the hose 38, and the microscopic holes of the vibration damping diaphragm 59, and the lower part of the liquid level detection diaphragm. Since the chamber 82 communicates with the atmosphere, the liquid level detection diaphragm 6 that has a pressure difference
0 is displaced downward (FIG. 8 (A), FIG. 9 (A),
(B)).

The plunger 65 provided in the lower portion of the liquid level detection diaphragm 60 is pushed by the displacement of the diaphragm 60 and is displaced downward, and the detection valve 68 provided in the upper chamber 83 of the third case 53 is pushed downward (see FIG. 9 ( B)).

When the displacement of the plunger 65 is lowered (the liquid level of sewage rises to a certain level), the detection valve 68 is reversed (ON operation) and the vacuum port of the passage 57A is opened (FIG. 9).
(C)). At this time, the plunger 65 moves the vacuum release passage 6
Close 5A (Fig. 6).

Due to the opening operation of the detection valve 68, the third case chambers 83 and 84 are evacuated (FIG. 9 (D)), and since the lower chamber 85 of the three-way valve diaphragm 70 is connected to the atmosphere, a pressure difference is generated. The resulting diaphragm 70 is pulled upwards,
Along with this, the valve body 71 also rises and moves from the valve seat 73 of the fifth case 55 to the valve seat 72 of the fourth case 54, and the chamber 86 communicating with the upper chamber of the working chamber 25 of the vacuum valve body is brought into a vacuum state. (FIG. 9 (E)). As a result, the vacuum valve 15 is opened due to the pressure difference between the upper and lower chambers of the working chamber 25 (the lower chamber is atmospheric pressure) (FIG. 9 (F)), and the dirty water in the tank is discharged into the vacuum sewer pipe 14
Are discharged to the printer (FIG. 8 (B), FIG. 10 (A)).

When the liquid in the tank is discharged, the pressurization of the liquid level detecting diaphragm 60 is lowered as the liquid level is lowered, and the liquid level detecting diaphragm 60 is gradually returned (see FIG. 10).
(B), (C)), the detection valve 68 that had been reversed first returns (OFF operation), the vacuum port of the passage 57A is closed, and the chamber 83,
No vacuum is introduced into 84 (FIG. 10 (D)).

When the liquid in the tank is discharged, the liquid level further lowers and the sewage surface drops to the end of the liquid level detection pipe 37 (FIG. 8C). The pressure becomes atmospheric pressure, and the spring 66 provided on the plunger 65
Is pushed back to the steady position by the vibration suppression diaphragm 5
Air immediately escapes from the outer peripheral edge of 9.

At the same time when the detection valve 68 is turned off by the plunger 65, the plunger 65 opens the vacuum release passage 65A (FIG. 7). Thereby, the room 83 of the third case 53
Becomes an atmospheric state, the pressure difference between both sides of the three-way valve diaphragm 70 disappears, and the spring 69 pushes the valve back to the original state (FIG. 10 (E)), and the valve body 71 also returns to the original valve seat of the fifth case 55. 7
3 is closed (FIG. 10 (F)), and the chamber communicating with the working chamber 25 of the vacuum valve body is brought to the atmospheric state. At this time, the atmosphere is taken in through the passage 92, but the chamber below the liquid level detection diaphragm 60 is depressurized through the vacuum release passage 65A,
Although the liquid level detection diaphragm 60 is tried to be drawn downward, the diaphragm 59 is drawn to the valve seat 101 to close the hole of the valve seat 101 and seal the upper chamber 81 of the liquid level detection diaphragm 60. Does not move downward, so that the plunger 65 located below this is not pushed down and the detection valve 68 is not activated again.

Atmosphere flows into the upper chamber of the working chamber 25 of the vacuum valve 15 through the atmospheric pressure connection port 58 of the controller section 27 and the atmosphere valve passage 43, and the differential pressure between the upper and lower chambers of the working chamber 25 disappears. 15 is closed (FIG. 8 (D), FIG. 10 (G)).

In the present invention, the spring constant of the spring 66 of the plunger 65 is optimized. This is because the position of the liquid level detection tube is lowered as compared with the conventional one, so that the vacuum valve 15 operates with a considerably small amount of dirty water as it is,
Since the opening time cannot be adjusted unlike the conventional method, the pressure relationship between the water level and the switch is adjusted to operate at a water level that allows suction of the amount of sewage that is a gas-liquid ratio commensurate with the amount of sucked air due to the pressure during air suction. The spring constant is changed in order to change. The spring may be strengthened to increase the suctioned wastewater amount, and weakened to decrease it. In the unit in which the amount of dirty water is adjusted by optimizing the spring constant of the plunger 65 as described above, no abnormality occurs due to the blockage of the conventional needle valve communication hole, and maintenance for readjustment is unnecessary.

The operation and effect of this embodiment will be described below. As long as the plunger 65 closes the vacuum release passage 65A, the vacuum valve 15 remains open. When the pressure acting on the liquid level detection diaphragm 60 becomes atmospheric pressure, the vacuum release passage 65A is opened. This is when the liquid pressure is not applied to the liquid level detection pipe 37 (the liquid pressure is applied to the diaphragm 60 as the internal pressure of the liquid level detection pipe 37 while the sewage is rising). When it reaches the position, air flows in from the vacuum release passage 65A opened by the plunger 65, and the vacuum valve 15 is closed. Here, by setting the pipe end of the liquid level detection pipe 37 at the same level as or slightly lower than the pipe end of the suction pipe 13, the time required for switching the three-way valve and closing the valve body of the vacuum valve 15 main body ( You can always think that it is almost a fixed time), but it will always suck air. Thereby, the vacuum sewer pipe 1 communicating with the vacuum valve 15
When the pressure of 4 is the set pressure, it goes without saying that the gas-liquid ratio of sewage and air will reach the set value, but if there is a significant drop in the vacuum pressure below the set pressure (at least the vacuum pressure at which the vacuum valve can operate). Also in (1), since the vacuum valve 15 always sucks air, a water block is less likely to occur as compared with the conventional product.

By eliminating the needle valve conduction function, the external air does not flow into the pressure control chamber (room 83) during the vacuum valve opening operation, so that the vacuum valve 15 is fully opened even under a lower vacuum pressure than before. It becomes possible.

(Second Embodiment) In the vacuum type waste water collecting apparatus 10 of the first embodiment, the passage 93 and the needle valve 74 provided in the controller portion 27 of the vacuum valve 15 are removed. The vacuum valve 15 can be stably opened / closed only by the opening / closing structure of the vacuum release passage 65A by the plunger 65 described above, which simplifies the structure.

(Third Embodiment) In the vacuum type waste water collecting apparatus 10 of the first embodiment, an intermediate portion of the hose 41 (the check valve 41A for guiding the vacuum pressure of the vacuum sewer pipe 14 to the controller portion 27 of the vacuum valve 15). The point of interposing the accumulator tank is added to the controller section 27 side). According to this, when the vacuum pressure of the vacuum sewer pipe is low, the vacuum pressure of the accumulator tank can be used as the operation source of the vacuum valve 15, and the opening operation of the vacuum valve is very stable. In terms of prevention of the above, due to the synergistic effect of the opening and closing structure of the vacuum release passage 65A by the plunger 65, the generation and recovery thereof can be remarkably improved as compared with the conventional case.

[0045]

As described above, according to the present invention, the gas-liquid ratio of sewage and air sucked into the vacuum sewer pipe is improved, and the vacuum valve is normally operated even when the vacuum pressure of the vacuum sewer pipe is low. It can be openable.

[Brief description of drawings]

FIG. 1 is a schematic diagram showing a vacuum type waste water collecting device.

FIG. 2 is a schematic diagram showing a vacuum valve.

FIG. 3 is a cross-sectional view showing a controller part of a vacuum valve.

FIG. 4 is an enlarged view showing a main part of FIG.

FIG. 5 is a schematic view showing a plunger.

FIG. 6 is a schematic diagram showing a detection valve ON state by a plunger.

FIG. 7 is a schematic diagram showing a detection valve off state by a plunger.

FIG. 8 is a schematic view showing the operation of the vacuum type waste water collecting device.

FIG. 9 is a schematic diagram showing the operating principle of a vacuum valve.

FIG. 10 is a schematic diagram showing the operating principle of a vacuum valve.

[Explanation of symbols]

 11 Tank 13 Suction Pipe 14 Vacuum Sewage Pipe 15 Vacuum Valve 24 Valve Body 25 Valve Working Chamber 26 Closing Force Applying Spring 27 Controller Section 60 Liquid Level Detection Diaphragm 65 Plunger 65A Vacuum Release Passage 67 Seal 68 Detection Valve (Detection Switch) 71 Valve Body (3-way valve) 83 rooms (pressure control room)

Claims (3)

[Claims] 1. A valve body that opens and closes a connecting portion between a suction pipe communicating with a tank and a vacuum sewer pipe communicating with a vacuum source, and a plunger connected to the valve body. A valve working chamber to be housed, a closing force applying unit that is built in the valve working chamber and applies a closing force to the valve body, and a controller unit that applies a vacuum pressure to the valve working chamber to apply an opening force to the valve body. In a vacuum valve configured to have the controller part, a three-way valve capable of switching and connecting a vacuum passage and an atmosphere passage to a valve working chamber, and a liquid level detection diaphragm that operates in response to a liquid level in a tank And a pressure control chamber for applying a vacuum force to the three-way valve so that the three-way valve connects the vacuum passage to the valve working chamber, and a vacuum force can be introduced into the pressure control chamber by being arranged in the pressure control chamber. Drive switch and liquid level detection diaphragm With is,
A plunger that is inserted into the pressure control chamber to turn on / off the detection switch, and after the plunger turns off the detection switch to stop the introduction of the vacuum force into the pressure control chamber, A vacuum valve, wherein a vacuum release passage for releasing a vacuum force in the pressure control chamber is opened. 2. The plunger is inserted into a vacuum release passage between a liquid level detection diaphragm lower atmosphere chamber and a pressure control chamber via a seal, and when the detection switch by the plunger is turned on, the plunger is released from the vacuum release passage. When the pressurization from the liquid level detection tube reaches atmospheric pressure after the detection switch by the plunger is turned off, the plunger is separated from the seal of the vacuum release passage and the vacuum is released. The vacuum valve according to claim 1, wherein the vacuum passage is configured to open the release passage. 3. The vacuum valve according to claim 1, wherein the pipe end of the liquid level detection pipe for detecting the liquid level of the tank is set at the same level as or lower than the pipe end of the suction pipe.