JPS5818555B2 - Teiatsurimitsutoben - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a limit valve provided in a flow path system for fluid such as fuel gas, and in particular, a limit valve that closes when the pressure of the fluid in the flow path system decreases below a desired value. This relates to a low pressure limit valve that works as follows.

As a conventional low pressure limit valve of this type, there is one shown in FIG.

In this known low-pressure limit valve, the passage 6 connecting the inlet port 2 and the outlet port 3 is configured to be opened and closed by a valve body 12 supported at the center of the second diaphragm 14, and is resettable. When the valve body 12 is moved to the open position via the button 11, if the supply pressure acting on the second chamber 5 through the passage 6 is equal to or higher than the set value, this second
The second diaphragm 14 that receives pressure from the chamber is connected to the valve body 1'.
2 Hold in the safe open position.

′=! At the octopus stage or at any time after that, the pressure in the second chamber 5 becomes less than the set value, and the gas pressure that presses the second diaphragm 14 acts in the opposite direction to the toggle springs 18, 18. When the pressure becomes lower than the pressing force of , the second (7) diaphragm 14 returns to its original state and the valve body 12
” to the closed position.

However, with the conventional low pressure limit valve as mentioned above,
When the valve body 12 is in the closing device Vc, the pressure on the S inlet port 2 side acts in the direction of opening this valve body, so the pressure at the inlet port 2 rises to a value that overcomes the pressing force of the toggle spring 18. In such a case, a situation may occur in which the valve body 12 opens even if the reset operation is not performed, and it cannot be said to be completely safe in terms of safety.

The purpose of this system is to sense when the pressure in the flow path system drops below the desired set value and automatically close the system, and to reset when the pressure in the flow path system rises again. To provide a low pressure limit valve that does not return to an open state unless operated.

One embodiment of the present invention will be described based on the drawings.
In the figure, reference numeral 1 indicates a valve case having an inlet port 2 connected to the fluid supply side and an outlet port 3 connected to the discharge side. A chamber 4 and a second chamber 5 connected to the exit boat 3 are formed, and the first and second chambers 4 and 5 are connected to a passage 6.
are in communication with each other via.

A valve rod 7 extending in a direction parallel to the axial direction of the passage 6 is inserted into the passage 6, and one end of the valve rod 7 is located within the first chamber 4 and is substantially perpendicular to the axis of the valve rod 7. A first diaphragm 8 arranged to form a pressure receiving surface
is fixed in the center.

A cover 10 having a ventilation hole 9 is provided outside the first diaphragm 8, so that the outer surface of the diaphragm 8 with respect to the first chamber 4 communicates with the outside air through the ventilation hole 9.

Further, a reset button 11 disposed coaxially with the valve rod 7 is supported on the cover 10 so as to be movable in the axial direction and biased away from the outer surface of the diaphragm 8 by a spring 11a. There is.

The other end of the valve rod 7 is located within the second chamber 5, and a disk-shaped valve body 12 is fixed to this end.

The valve body 12 is movable together with the valve rod 7 between a closed position in which it contacts a valve seat 13 formed at one end of the passage 6 and an open position in which it is spaced at an appropriate distance from the valve seat 13.
One surface thereof is fixed to the inner surface of a second diaphragm 14 located within the second chamber 5.

This diaphragm 14 has an actual pressure surface substantially perpendicular to the axis of the valve rod 7, and the effective area of this pressure receiving surface is selected to be sufficiently larger than that of the first diaphragm 8.

Further, a cover 16 having a ventilation hole 15 is provided on the outer side of the diaphragm 14 with respect to the second chamber 5. Therefore, the outer surface side of the second diaphragm 14 with respect to the second chamber 5 is exposed to outside air through the ventilation hole 15. communicated.

Also, between the adjusting screw 17 screwed into the cover 16 and the diaphragm 14, when the pressure of the fluid in the first chamber 4 is lower than a desired set value, the diaphragm 14
A spring 18 is interposed to hold the valve body 12 in the closed position.

Therefore, when the pressure of the fluid flowing into the first chamber 4 through the port 2 is higher than the desired set value, this pressure is applied to the pressure receiving surface of the first diaphragm 8 and the pressure receiving surface of the second diaphragm 14. However, since the effective area of the latter is sufficiently larger than that of the former, the first diaphragm 8, the valve rod 7, the valve body 12, and the second diaphragm 14 are integrally connected to the valve. The body 12 is held in a position spaced apart from the valve seat 13.

FIG. 1 shows this state.

In this state, since the valve body 12 is held in the open position, the first and second chambers 4 and 5 are in communication with each other,
The fluid supplied to the inlet port 2 enters the first chamber 4 and the passage 6.
and exits from the outlet port 3 through the second chamber 5.

Now, if the pressure of the fluid in the first chamber 4 becomes lower than the set value (this can be set to any value by selecting the position of the adjusting screw 11), then the second diaphragm 1
4. Due to the decrease in the pressure acting on the pressure receiving surface, the valve element 12 is pressed into the second chamber 5 by the action of the spring 18, and the valve body 12 moves together with the valve rod 7 and comes into pressure contact with the valve seat 13. The communication between the first chamber 4 and the second chamber 5 is cut off.

After this state is reached, even if the pressure of the fluid in the first chamber 4 rises again beyond the set value, this pressure will be maintained at the valve body 12.
Since it acts to press the first diaphragm 8 in the opposite direction while pressing it toward the open position, the effective area of the pressure-receiving surface of the diaphragm 8 is sufficiently larger than the cross-sectional area of the passage 6. If set, the valve body 12 will not be moved to the open position.

However, if the operator detects that the fluid pressure has returned to a steady value and manually presses the reset button 11, the reset button 11 will reset the first diaphragm 8, valve rod 7, valve body 12, and second diaphragm 14. The valve body 12 is moved in the direction away from the valve seat 13, and fluid pressure also acts on the pressure receiving surface of the second diaphragm 14, so that even if the reset button 11 is released, the valve body 12 remains in the open position. Retained.

Further, as shown in FIG. 2, a magnetically permeable material 19 such as an iron plate is attached to the outer surface of the first diaphragm 8, and a permanent magnet 20 is attached to the inner surface of the cover 10 (this may be the reverse). For example, the valve body 12 can be moved to the closed position and held at this position more reliably.

As described above, the present invention forms a first chamber connected to the inlet port and a second chamber connected to the outlet port in the valve case, and the first and second chambers are interconnected through a passage. and a first diaphragm having an effective area larger than the cross-sectional area of the passage is provided in the first chamber, and a first diaphragm having an effective area larger than the first diaphragm in the second chamber. A second diaphragm is provided in the second chamber, and the second diaphragm has a closed position in which it abuts a valve seat formed at one end of the passage, and a second position spaced apart from the valve seat. fixing a valve body moving between the passageway and the first diaphragm at an end located within the first chamber;
and a valve rod fixed to the valve body at an end located in the second chamber, and inserted through the passage so as to be movable in the axial direction of the passage, and the first and second diaphragms of the first and second diaphragms. The outside of the second room communicates with the outside air.

Between the valve case and the second diaphragm, the valve body is moved to a closed position when the pressure in the first chamber falls below a desired set value, and the cross-sectional area of the passage and the Since a spring is provided to hold the valve body in the closed position based on the difference in the effective area of the first diaphragm, when the valve body is in the open position, The valve body is held in the open position by the applied force, but when the supply pressure drops below the set value, the valve body is moved to the closed position by the biasing force acting on the second diaphragm.

Once the valve body reaches the closed position, the supply pressure no longer acts on the second diaphragm, but acts on the first diaphragm and the valve body.

Here, since the effective area of the first diaphragm is larger than the cross-sectional area of the passage, a force corresponding to this difference acts to press the first diaphragm to the closed position of the valve body.

In other words, as the supply pressure rises, the force that holds the valve body in the closed position increases, so unlike the conventional low-pressure limit valves mentioned above, there is no inconvenience of the valve opening even if the supply pressure rises, and once the supply pressure increases, the valve remains closed. After reaching the closed state, even if the fluid pressure rises above the set value again, the closed state can be maintained unless another reset operation is performed, ensuring an extremely high level of safety. There is an advantage that it can be done.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of a low pressure limit valve according to an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of a low pressure limit valve according to another embodiment of the invention, and FIG. 3 is a longitudinal sectional view of a conventional low pressure limit valve. It is a front view. DESCRIPTION OF SYMBOLS 1... Valve case, 2... Inlet port, 3... Outlet port, 4... First chamber, 5... Second chamber, 6...
・Passage, 7...Valve rod, 8...Diaphragm, 9
...Vent hole, 10...Cover, 11...Reset button, 11a...Spring, 12...Valve body, 1
3...Valve seat, 14...Diaphragm, 15...Vent hole, 16...Cover, 17...Adjustment screw, 1B.
...Spring, 19...Magnetic permeable material, 20...Permanent magnet, 21...Pressure regulating valve.

Claims (1)

[Claims] 1 A first chamber connected to the inlet port and a second chamber connected to the outlet port are formed in the valve case, and the first and second chambers are communicated with each other via a passage, and the first chamber is connected to the outlet port. A first diaphragm having an effective surface larger than the cross-sectional area of the passage is provided in the first chamber, while a first diaphragm having an effective surface larger than the cross-sectional area of the passage is provided in the second chamber.
A second diaphragm having an effective area larger than the multiple diaphragms of the vehicle L' is provided in the chamber, and in the second chamber, the second diaphragm is provided with a second diaphragm formed at one end of the passage. A valve body that moves between a closed position in which it contacts the valve seat and a second position that is spaced from the valve seat is fixed, and a valve body is further provided in the onboard passageway at an end located in the first chamber. A valve rod fixed to the first diaphragm and fixed to the valve body at an end located in the second chamber is inserted movably in the axial direction of the passage,
Moreover, the outer surfaces of the first and second diaphragms relative to the first and second chambers are communicated with the outside air, and the main valve case and the second chamber are connected to the outside of the second chamber.
diaphragm, the valve body is moved to the closed position when the pressure in the first chamber falls below a desired set value, and the cross-sectional area of the passage and the effective A low-pressure limit valve equipped with a spring that holds the valve body in the closed position by compressing the area.