JPH0960740A - Diaphragm valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make fluid flow controllable not only through a space between a first port at the first chamber where a valve seat is provided, and a third port but also through spaces in the middle of a second port at the side opposite to the valve seat, the first port and the third port, and concurrently have a check valve built in without providing an extra space. SOLUTION: A through hole 21 is provided at the center of a diaphragm 2, concurrently a circular valve part 22 circularly enclosing the through hole 21 is also provided, a valve seat part 6 capable of being in contact with/parted from the circular valve part 22 of the diaphragm 2, is provided for a first chamber 11, a circular third chamber 13 provided with a circular opening part 13a to be opened/closed by the circular valve part 22, is provided for the valve seat part 6, and a valve box is provided with a first port 1a communicating with the first chamber 11, a second port 1b communicating with a second chamber 12, and with a third port 1c communicating with the third chamber 13 in the inside of the valve seat part 6.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm valve applicable to, for example, a flow path switching valve of a fuel vapor outflow prevention device for an automobile.

[0002]

2. Description of the Related Art As a conventional diaphragm valve, for example, there is one shown in FIG.

That is, the hollow inside of the hollow inner valve box 100 is divided by a flexible diaphragm 101 into two chambers, a first chamber 102 and a second chamber 103. Diaphragm 1
A valve portion 104 is provided in the center of 01, and a valve seat portion 105 with which the valve portion 104 comes in contact with and separates from the first chamber 102. In addition, the valve portion 104 is provided in the second chamber 103.
A spring 10 that always urges the spring 5 in a direction of pressing it.
7 are provided.

On the other hand, the valve seat portion 105 is provided with a third chamber 106 having an opening portion 106a which is opened and closed by the valve portion 104, and the valve box 100 is provided with a first chamber 102 which communicates with the first chamber 102. The port 102a, the second port 103a communicating with the second chamber 103, and the third port communicating with the third chamber 106.
A port 106a is provided.

Normally, the valve portion 104 is pressed against the valve seat portion 105 by the spring force of the spring 107, and the third chamber 106
The opening 106a of the first port is closed, and the first and third ports 103 are closed.
The connection between a and 106a is cut off.

When the fluid pressure acting from the first and third chambers 103 and 106 side becomes larger than the fluid pressure acting from the second chamber 102 side and the differential pressure becomes larger than the load of the spring 107, the diaphragm 101. Is the second chamber 102
And the valve portion 104 is separated from the valve seat portion 105 to the third side.
The opening 106a of the chamber 106 opens, and the first and third ports 1
The communication between 02a and 106a is established.

[0007]

However, in the above-mentioned conventional diaphragm valve, the diaphragm 101 is used.
Completely inside the valve box 100 by the first and second chambers 102, 1
Since it is separated into 03, the first port 102a and the third port 102a
It was not possible to establish a flow path configuration in which the communication between the first port 102a and the second port 103a or between the third port 106a and the second port 103a was achieved only by switching the communication / blocking state between the ports 106a. .

Further, when the check valve is provided in the flow path of the diaphragm valve, it is necessary to separately provide a space dedicated to the check valve, which makes the structure complicated and difficult to manufacture.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art.
By forming a flow path through which the fluid to be controlled flows in the diaphragm, not only between the first port and the third port on the side of the first chamber where the valve seat portion is provided, but also the second chamber on the opposite side of the valve seat portion. It is to provide a diaphragm valve capable of controlling the flow of fluid between the second port on the side and the first and third ports.

Another object of the present invention is to provide a diaphragm valve capable of incorporating a check valve without providing an extra space.

[0011]

In order to achieve the above object, according to the present invention, the hollow inside of the hollow internal valve box is divided into a first chamber and a second chamber by a flexible diaphragm. The diaphragm is divided into chambers and a through hole is provided in the center of the diaphragm, and an annular valve portion surrounding the through hole is provided, and the annular valve portion is provided on the first chamber side by the bending deformation of the diaphragm. A valve seat portion that can be brought into contact with and separated from the valve seat portion is provided, and an annular third chamber having an annular opening portion that is opened and closed by the annular valve portion is provided inside the valve seat portion. A biasing means for constantly biasing the annular valve portion in the direction of pressing the valve seat portion is provided, and the valve box communicates with the first port communicating with the first chamber and the second chamber. A second port and a third port communicating with the third chamber inside the valve seat portion are provided. And butterflies.

According to the present invention, normally, the diaphragm is pushed from the second chamber side to the first chamber side by the urging force of the urging means, the diaphragm is extended by this pressing force, and the valve portion is moved to the valve seat portion. The openings are closed by being pressed against each other, and the first, second, and third ports are mutually closed.

When the fluid pressure acting from the first chamber side and the third chamber side of the diaphragm becomes larger than the fluid pressure acting from the second chamber side and the pressure difference exceeds the urging force of the urging means, the diaphragm moves. Bends to the second chamber side, and the valve section moves to the second
It moves to the chamber side and separates from the valve seat portion and the opening opens. As a result, the first, second, and third chambers are in communication with each other, and the fluid on the first and third chamber sides moves to the second chamber side.

Further, inside the valve seat portion, a fourth chamber communicating with the third chamber is formed inside the annular third chamber, and the portion of the valve seat portion facing the second chamber through the through hole of the diaphragm. In addition, the flow of the fluid from the fourth chamber side to the second chamber side is blocked, and when the pressure difference between the second chamber and the fourth chamber becomes a predetermined pressure or more, the second chamber side moves to the fourth chamber side. It is characterized in that a check valve is provided to allow the passage of the fluid.

With this configuration, in the valve closed state in which the valve portion of the diaphragm is seated on the valve seat portion, the pressure on the third chamber side becomes a negative pressure and the pressure difference from the second chamber side exceeds the set pressure. Then, the check valve opens and the negative pressure is released.

In this way, two-way control is possible, that is, control for moving the fluid from the first and third chamber sides to the second chamber side and control for moving the fluid from the second port side to the third port side.

Further, the second port communicating with the second chamber is connected to the evaporation line communicating with the canister, the first port is connected to the filler tube of the fuel tank, and the third port of the fuel cutoff valve provided at the upper end of the fuel tank. When connecting to the pressure relief hole, it operates as follows.

The internal pressure of the filler tube acts on the first chamber through the first port, and the internal pressure of the fuel tank acts on the third chamber through the third port. On the other hand, the pressure of the evaporation line acts on the second chamber through the second port.

Normally, the valve portion is pressed against the valve seat by the urging force of the urging means so that the first, second and third ports are in a mutually closed state.

Here, when the internal pressure in the fuel tank rises due to the temperature rise during parking, a third port
The internal pressure of the chamber increases. Further, since the filler tube has a closed fuel supply port, the pressure in the filler tube is equal to the tank internal pressure, and the tank internal pressure also acts on the first chamber through the first port communicating with the filler tube. When the fluid pressure acting from the first chamber side and the third chamber side becomes larger than the fluid pressure acting from the second chamber side and the pressure difference exceeds the urging force of the urging means, the diaphragm moves toward the second chamber side. Bends to
Along with that, the valve portion moves to the second chamber side, separates from the valve seat portion, and the opening portion opens. As a result, the fuel vapor flows into the evaporation line through the through hole in the center of the diaphragm, the second chamber and the second port, flows into the canister through the evaporation line, and the inside of the fuel tank is depressurized.

At the time of refueling, the refueling port of the filler tube opens, so that the first chamber becomes atmospheric pressure through the first port,
The pressure in the fuel tank acts only on the third chamber through the third port. Since the pressure receiving area of the diaphragm facing the third chamber is small, the diaphragm cannot be deflected to the second chamber side by overcoming the urging force of the urging means.

Therefore, after the refueling cutoff valve, which is separately provided, is closed, the air in the fuel tank loses its place, the liquid level of the filler tube rises, and refueling is stopped.

Further, in the case where the check valve is provided, when the inside of the fuel tank has a negative pressure with the filler tube filler port closed, the negative pressure is introduced into the fourth chamber through the third port and the third chamber. , The check valve opens when the pressure difference from the second chamber side exceeds the set pressure. As a result, air is introduced from the canister into the fuel tank through the evaporation line, the second port, the second chamber, the through hole, the check valve, the fourth, third chamber, the third port and the pressure relief holes of the fuel cutoff valve. Is
The deformation of the fuel tank is prevented.

[0024]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below with reference to the embodiments shown in the drawings.

[First Embodiment] FIGS. 1 to 3 show a diaphragm valve according to a first embodiment of the present invention.

That is, reference numeral 1 denotes the whole diaphragm valve. The diaphragm valve 1 is roughly composed of a housing 1 as a hollow inner valve box, and the inside of the housing 1 is divided into a first chamber 11 and a second chamber 12. And a flexible diaphragm 2 for partitioning.

The diaphragm 2 is a film-like member made of a rubber-like elastic material, and a through hole 21 is provided at the center thereof.
An annular valve portion 22 that surrounds 1 in an annular shape is provided. An annular convex portion 23 for sealing is concentrically formed on the inner and outer ends of the annular valve portion 22. Also, the diaphragm 2
A retainer 3 is attached to the side surface of the second chamber 12 side. The retainer 3 includes a washer-shaped annular plate portion 31 that abuts the back surface of the annular valve portion 22, and a cylindrical portion 32 that projects toward the second chamber 12 so as to surround the outer diameter end of the annular plate portion 31.
It is composed of

On the other hand, the housing 1 is divided into an upper cap 4 and a lower cap 5 which are connected to each other with the diaphragm 2 as a boundary. The second chamber 12 is formed on the upper cap 4 side, and the first chamber is formed. 11 is the lower cap 5
Formed on the side.

On the side of the first chamber 11, there is provided a valve seat portion 6 with which the annular valve portion 22 can be brought into and out of contact by the expansion and contraction operation of the diaphragm 2. Inside the valve seat portion 6, the annular valve portion 22 opens and closes. Annular third provided with an annular opening 13a
A chamber 13 is provided.

The valve seat portion 6 includes a lower bottom wall 51 of the lower cap 5.
Cylindrical projection at the center of. An annular third chamber 13 is formed inside the valve seat portion 6, and the annular third chamber 1 is formed.
Inside the third chamber 3, a fourth chamber 14 communicating with the third chamber 13 is provided.

The fourth chamber 14 includes a third chamber 13 and an annular wall 61.
The upper end of the annular wall 61 is closed by the partition wall 62 and the lower end is open. A lid 63 is fitted into the lower end opening of the annular wall 61 to seal the fourth chamber 14.

Then, the diaphragm 2 of the valve seat portion 6 is
The partition wall 62, which is located at a portion facing the second chamber 12 through the through hole 21, prevents the fluid from flowing from the fourth chamber 14 side to the second chamber 12 side, and prevents the fluid from flowing through the second chamber 12 and the second chamber 12. A check valve 7 is provided that allows the fluid to flow from the second chamber 12 side to the fourth chamber 14 side when the pressure difference in the four chambers 14 becomes a predetermined pressure or more.

This check valve is a so-called umbrella-shaped valve, and is provided at a valve shaft 71 fitted in a fixing hole 62a formed through the flat partition 62 and at the end of the valve shaft 71 on the fourth chamber 14 side. And a flexible umbrella seal portion 72 that opens in an umbrella shape, and is integrally formed of a rubber-like elastic material. The umbrella seal portion 72 is in close contact with the side surface of the flat partition wall 62 on the side of the fourth chamber 14 by its elastic restoring force, and closes the check valve hole 62b formed around the fixing hole 62a. There is.

Therefore, the check valve 7 is assembled as follows.
As shown in FIG. 3, it suffices to insert the valve shaft 71 into the fixing hole 62a of the plate-shaped partition wall 62 by inserting it from the lower end opening portion of the annular wall 61, and it can be mounted very easily.

On the other hand, the second chamber 12 is provided with a spring 8 as a biasing means for constantly biasing the annular valve portion 22 of the diaphragm 2 against the valve seat portion 6. One end of the spring 8 is engaged with an annular spring receiver 33 provided on the annular plate portion 31 of the retainer 3 and the other end is engaged with the upper bottom wall 41 of the upper cap 4. A retainer guide 4 for guiding the outer periphery of the retainer 61 is provided at the corners of the upper bottom wall 41 and the side wall 42 of the upper cap 4.
3 are provided.

Further, the housing 1 includes the first chamber 11
A first port 1a that communicates with the second chamber 1 and a second port 1b that communicates with the second chamber 12 and a third port 1c that communicates with a third chamber 13 inside the valve seat portion 6 are provided.

According to the present invention, the diaphragm 2 is normally moved from the second chamber 12 side to the first side by the spring force of the spring 8.
The diaphragm 2 is pushed by the chamber 11 side by this pushing force.
Bends, the valve portion 22 is pressed against the valve seat portion 6, the opening portion 13a of the third chamber 13 is closed, and the first, second and third ports 1a, 1b, 1c are mutually closed. .

The first chamber 11 and the third chamber 13 of the diaphragm 3
When the fluid pressure acting from the side becomes larger than the fluid pressure acting from the second chamber 12 side and the pressure difference exceeds the spring force of the spring 8, the diaphragm 3 bends toward the second chamber 12 side, and accordingly. The annular valve portion 22 moves to the second chamber 12 side, separates from the valve seat portion 6, and the opening 13a opens. As a result, the first, second and third chambers 11, 12, 13 are in communication with each other, and the fluid on the first, third chamber 11, 13 side moves to the second chamber 12 side.

In the closed state where the annular valve portion 22 of the diaphragm 2 is seated on the valve seat portion 6, the pressure of the third port 1c becomes negative and the pressure of the second port 1b becomes the third port 1c. When the pressure becomes relatively larger than the pressure and the pressure difference becomes equal to or higher than the set pressure, the check valve 7 opens and the control fluid moves from the second port 1b side to the third port 1c side.

As described above, the first and third ports 1a and 1c
It is possible to perform control in two directions, that is, the control for moving from the second port 1b side to the side and the control for moving from the second port 1b side to the third port 1c side.

FIG. 4 shows an example of a system configuration when the diaphragm valve 1 of the present invention is used in a fuel vapor outflow prevention device (evaporation loss prevention device) from a fuel tank.

To briefly explain this system configuration, the fuel vapor flowing out from the fuel tank 200 is adsorbed to the canister 203 filled with activated carbon through the vent line 201 and the evaporation line 202, and when the engine 204 is operating, the air is passed through the canister vent valve 205. The purge amount of the separated fuel is controlled by the purge control valve 206 to control the intake system 2 of the engine 204.
It inhales to 07.

The vent line 201 guides the air in the tank 200, which is replaced with fuel when fuel is refueled, to the canister 203 without releasing it to the atmosphere. One end is connected to the canister 203 and the other end is connected to the vapor control valve 2.
08 and the fuel cutoff valve 209
Connected to. Also, the vapor control valve 209
Communicate with the interior of the filler tube 211 via the first flow path 210.

On the other hand, the evaporation line 202 is connected to the tank 200 by the fuel vapor evaporated due to the temperature rise during parking or the like.
In order to prevent the internal pressure from rising, the fuel vapor is guided to the canister 203. One end is connected to the canister 203 and the other end is connected to the second port 1b of the diaphragm valve 1 of the present invention.

Further, the third port 1c of the diaphragm valve 1
Is connected via a second flow path 213 to a relief port 212b communicating with a pressure relief hole 212a of a fuel cutoff valve 212 provided at the upper end of the second flow channel fuel tank 200, and the first port 1a is connected to the first port 1a. It is connected to the filler tube 211 of the fuel tank 200 via the flow path 210.

The refueling shutoff valve 209 is used for the fuel tank 200.
The float valve 209a, which has a lower specific gravity than the fuel inside and moves following the liquid level of the fuel, is provided to shut off the air displacement hole 209b leading to the vent line when the liquid level reaches a predetermined level. Has become.

Further, the vapor control valve 208
Is the canister open chamber 2 in which the inside of the housing 208a communicates with the vent line 201 by the diaphragm 208b.
08c and the control room 2 communicating with the filler tube 211
08d. Also, the canister open room 2
08c is located on the downstream side of the air replacement hole 209b, and is provided with an annular valve seat 208e that surrounds the air replacement hole 209b.

The fuel cutoff valve 212 has a pressure relief hole 212a through which the pressure in the fuel tank 200 escapes, and the pressure relief hole 212a rises when the vehicle tilts or falls.
Is provided with a float valve 212c.

Next, the operation of the diaphragm valve 1 in this system will be described with reference to FIG.

In the diaphragm valve 1, the first chamber 11
The internal pressure in the filler tube 211 acts through the first port 1a, and the third chamber 13 receives the third port 1a.
The internal pressure of the fuel tank 200 is acting through c. On the other hand, the second chamber 12 has a second port 1b and an evaporation line 20.
The pressure of the canister 203 is acting through 2.

The main flow path in the case of this use example is a flow path connecting the second port 1b and the third port 1c and passing through the second chamber 12, the through hole 21 and the third chamber 13, and the first port 1a functions as a control line for controlling the diaphragm 2.

Normally, the annular valve portion 22 of the diaphragm 2 is pressed against the valve seat portion 6 by the spring force of the spring 8 so that the first, second and third ports 1a, 1b, 1c are closed. ing.

Here, when the internal pressure in the fuel tank 200 increases due to the temperature increase during parking, the internal pressure in the third chamber 13 increases through the third port 1c. Further, since the filler port 211a of the filler tube 211 is closed, the pressure in the filler tube 211 is equal to the tank internal pressure, and the tank internal pressure also acts in the first chamber 11 through the first port 1a communicating with the filler tube 211. To do. The total sum of the fluid pressures acting on the first and third chambers 11 and 13 is larger than the fluid pressure acting on the second chamber 12 (internal pressure of the canister), and the differential pressure thereof is larger than the spring force of the spring 8. Then, as shown in FIG. 5A, the diaphragm 2 is bent toward the second chamber 12 side, the annular valve portion 22 is separated from the valve seat portion 6, and the fuel vapor is separated from the through hole 21 and the second hole in the center of the diaphragm 2.
Evaporation line 20 through chamber 12 and second port 1b
2 to the canister 2 through the evaporation line 202.
03, the inside of the fuel tank 200 is depressurized.

At the time of refueling, the refueling port 211a of the filler tube 211 is opened, so that the first port 1a becomes atmospheric pressure, and the diaphragm 2 is acted on by the pressure in the fuel tank 200 only through the third port 1c to the third chamber 13. . Since the pressure receiving area of the diaphragm 2 facing the third chamber 13 is small, the diaphragm 2 cannot be deflected toward the second chamber 12 side by overcoming the spring force of the spring 8 as shown in FIG. 5B.

Therefore, after the refueling cutoff valve 209 is closed by the float valve 209a, the air in the fuel tank 200 loses its place, the liquid level of the filler tube 211 rises, and refueling is stopped.

On the other hand, the filler port 2 of the filler tube 211
When the inside of the fuel tank 200 has a negative pressure with 11a closed, the first and third chambers 11 and 13 of the diaphragm 2 are
The negative pressure in the tank 200 acts on the pressure receiving surface facing the valve seat portion 6 while the annular valve portion 22 of the diaphragm 2 remains closed.
The contact surface pressure with increases. On the other hand, negative pressure is introduced into the fourth chamber 14 of the check valve 7, and the fourth chamber 1
When the pressure difference between the pressure acting on the fourth side and the pressure acting on the second chamber 12 exceeds a predetermined pressure, the umbrella-shaped sealing portion 72 of the check valve 7 opens, as shown in FIG. Air is introduced from the 203 side, the negative pressure is released, and the deformation of the fuel tank can be prevented.

Further, in the case of this diaphragm valve 1, the second port 1b is communicated with the canister 203, and the third port 1c is communicated with the pressure relief port 212a of the fuel cutoff valve 212 provided at the upper end of the fuel tank 200. Further, since the first port 1a is communicated with the filler tube 211 of the fuel tank 200, even if the fuel vapor permeates the diaphragm 2, the fuel vapor is not released to the atmosphere.

[Second Embodiment] FIG. 6 shows a second embodiment of the present invention.

In the second embodiment, the check valve 7 in the first embodiment is eliminated. In the first embodiment, the check valves 7 from the first and third chamber sides to the second chamber side are removed. While the flow of the fluid and the control of the flow of the fluid from the second chamber side to the third chamber side are controlled, the flow of the fluid in the two directions is controlled. , Third chamber 11, 13
The difference is that the flow is controlled in one direction only from the side to the second chamber 12 side.

Since the other structure and operation are exactly the same as those of the first embodiment, the same components are designated by the same reference numerals and the description thereof will be omitted.

[0061]

As described above, according to the present invention,
Since the through hole is provided in the diaphragm for use as a flow path, not only between the first port and the third port on the first chamber side where the valve seat portion is provided, but also the second port on the opposite side of the valve seat portion. It is possible to control the flow of fluid between the second port and the first and third ports on the chamber side.

Moreover, since the check valve is provided by utilizing the space inside the annular third chamber formed in the valve seat portion, an extra space for the check valve is unnecessary.

Further, by connecting the second port to the canister, the third port to the pressure relief port of the fuel cutoff valve provided at the upper end of the fuel tank, and the first port to the filler tube of the fuel tank. Since the diaphragm chamber is not exposed to the atmosphere, even if the fuel vapor permeates the diaphragm, the fuel vapor is not exposed to the atmosphere.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a diaphragm valve according to a first embodiment of the present invention in a closed state.

2 (a) and 2 (b) are diagrams showing an operating state of the diaphragm valve of FIG.

FIG. 3 is an exploded sectional view of the diaphragm valve of FIG.

FIG. 4 is a diagram showing a system configuration example of a fuel outflow prevention device in which the diaphragm valve of FIG. 1 is used.

5 is an explanatory view of an operating state of the diaphragm valve of FIG.

FIG. 6 is a sectional view of a diaphragm valve according to a second embodiment of the present invention.

FIG. 7 is a cross-sectional view of a conventional diaphragm valve.

[Explanation of symbols]

 1 Diaphragm valve 1a 1st port 1b 2nd port 1c 3rd port 2 Diaphragm 21 Through hole 22 Annular valve part 23 Annular convex part 3 Retainer 31 Annular plate part 32 Cylindrical part 33 Spring receiving 4 Upper cap 41 Upper bottom wall 42 Side wall 43 Retainer guide 5 Lower cap 51 Lower bottom wall 6 Valve seat 61 Ring wall 62 Flat partition 62a Fixing hole 62b Check valve hole 63 Lid 7 Check valve 71 Valve shaft 72 Umbrella seal part 11 1st chamber 12 2nd chamber 13th 3 chambers 13a opening 14 4th chamber 200 fuel tank 201 vent line 202 evaporation line 203 canister 204 engine 205 canister vent valve 206 purge control valve 207 engine 208 vapor control valve 208a housing 208b diaphragm 20 c canister open chamber 208d control chamber 208e valve seat 209 refueling shutoff valve 209a float valve 209b air displacement holes 210 first flow passage 211 filler tube 211a filler opening 212 fuel cutoff valve 212a pressure relief holes 212b relief port 212c float 213 second flow path

Claims (3)

[Claims] 1. A hollow interior of a hollow inner valve box is divided into two chambers, a first chamber and a second chamber, by a flexible diaphragm, and the diaphragm is provided with a through hole in the center thereof.
An annular valve portion that annularly surrounds the through hole is provided, and a valve seat portion that can be brought into contact with and separated from the annular valve portion by flexural deformation of the diaphragm is provided in the first chamber, and the annular valve is provided inside the valve seat portion. An annular third chamber having an annular opening that is opened and closed by a section is provided, and the second chamber constantly biases the annular valve portion of the diaphragm against the valve seat portion. A biasing means is provided, and the valve box has a first port communicating with the first chamber, a second port communicating with the second chamber, and a third port communicating with a third chamber inside the valve seat portion. The diaphragm valve is characterized in that and are provided. 2. A fourth chamber communicating with the third chamber is formed inside the annular third chamber inside the valve seat portion, and a fourth chamber is formed through a through hole of the diaphragm of the valve seat portion.
When the pressure difference between the second chamber and the fourth chamber is equal to or more than a predetermined pressure, the fluid is prevented from flowing from the fourth chamber side to the second chamber side in a portion facing the chamber, The diaphragm valve according to claim 1, further comprising a check valve that allows the fluid to flow into the four chambers. 3. A second port communicating with the second chamber is connected to an evaporation line communicating with the canister, a first port is connected to a filler tube of a fuel tank, and a third port of a fuel cutoff valve provided at the upper end of the fuel tank. The diaphragm valve according to claim 2, wherein the diaphragm valve is connected to the pressure relief hole.