JPH07225619A - Reducing valve for vacuum - Google Patents

Abstract

PURPOSE:To obtain the reducing valve for vacuum which can precisely set fine pressure. CONSTITUTION:A diaphragm 19 is arranged while being interposed between a lower diaphragm presser 10 and an upper diaphragm presser 21. A through hole 9 is formed in the lower diaphragm presser 10. A piston 12 is arranged slidably in the upper diaphragm presser 21. A coil spring 38 in a tensed state is fitted to the top surface of the piston 12. A through hole 26 is formed in the center of the piston 12 and a selector valve body 28 is arranged on the top surface. The selector valve body 28 is fitted so that it can be moved up and down from outside through a valve shaft 27. Further, the reverse surface chamber 30 of the diaphragm 19 is connected to another vacuum source through a connection port.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve for maintaining a pressure value on the outlet side of a valve at a predetermined vacuum pressure equal to or lower than atmospheric pressure, and more particularly to a vacuum pressure reducing valve capable of setting a minute pressure. Normally, the pressure reducing valve detects a decrease in pressure on the outlet side of the valve, opens the valve opening when the pressure receiving response portion detects the pressure, and supplies high pressure fluid on the inlet side to the outlet side to maintain a desired pressure. In order to maintain the outlet side pressure at a vacuum pressure below atmospheric pressure, as in the case of a pressure reducing valve, the direction in which the initial load is applied to the pressure receiving response part is opposite to that of the pressure reducing valve that maintains a positive pressure above atmospheric pressure. The pressure reducing valve is used.

[0002]

2. Description of the Related Art As a conventional vacuum pressure reducing valve, for example, the one disclosed in Japanese Utility Model Laid-Open No. 63-14311 has been used. This is because one side of the diaphragm as the pressure receiving responder receives the pressure on the secondary side, that is, the outlet side, the other side is connected with the pressure setting spring, and this pressure setting spring is placed in a tensioned state, so that the outlet side Is set and maintained at a predetermined vacuum pressure below atmospheric pressure.

[0003]

SUMMARY OF THE INVENTION In the above conventional one,
There was a problem that the minute pressure could not be set accurately. The pressure is set by changing the spring load of the pressure setting spring by an external operation, but at the time of setting a minute pressure, the spring length must be minutely changed to slightly change the spring load. This is because it is difficult to accurately and minutely change the length of the spring. The spring length is usually changed by a screw mechanism connected to the spring, but it is practically impossible to make a fine displacement with high precision due to play in the screw mechanism. In particular, when the spring constant of the pressure setting spring is large, the spring load changes greatly even with a slight change in the spring length, which makes it difficult to set the pressure more accurately.

Therefore, a technical problem of the present invention is that the spring load can be minutely changed without minutely changing the length of the spring so that a minute pressure can be set with high precision. To get a valve.

[0005]

[Technical Means for Solving the Problems] The technical means of the present invention taken to solve the above problems is to provide a valve opening between an inlet and an outlet and dispose a valve element facing the valve opening. Then, the valve body is connected to the pressure receiving part, and the pressure on the outlet side is applied to one surface of the pressure receiving part, and the pressure setting spring is connected to the other surface to detect that the pressure on the outlet side has dropped below the set pressure. In the pressure reducing valve that detects the response portion and opens the valve opening to supply the inlet side fluid to the outlet side to maintain the outlet side pressure at the set pressure, in the pressure receiving response portion other surface side and a predetermined vacuum source. A communication passage communicating with the pressure-responsive element is formed through a pressure-responsive element, and the other side of the pressure-responsive element is disconnected from the vacuum source by the responsive displacement of the pressure-responsive element.

[0006]

The other side of the pressure receiving section can be maintained at a predetermined vacuum pressure by the other side of the pressure receiving section communicating with the vacuum source due to the responsive displacement of the pressure responsive element. Therefore, the vacuum pressure acts on both surfaces of the pressure receiving responsive portion to cancel each other, and the load received by the pressure receiving responsive portion becomes small. The spring load of the pressure setting spring may be small as much as the load is small, and the small spring load can also make the spring constant small. Therefore, since the spring constant is small, it is not necessary to minutely change the length of the spring when minutely changing the spring load to set the minute pressure, and the spring length is relatively changed. As a result, the spring load can be minutely changed, the difficulty of minutely changing the spring length is eliminated, and the minute pressure can be set accurately.

[0007]

EXAMPLES Examples showing specific examples of the above technical means will be described. In FIG. 1, an inlet 2 and an outlet 3 are formed in a valve casing 1, and a valve port 5 is formed in a valve seat member 4 attached to the valve casing 1. A flat main valve body 6 facing the valve opening 5
Is arranged so as to be biased in the valve closing direction by a coil spring 17, and the upper surface thereof is joined to the connecting rod 8 of the piston 7.

The upper portion of the piston 7 is connected to the pilot valve chamber 14 via the communication passage 13. A pilot valve body 15 is arranged at the end of the pilot valve chamber 14 with a coil spring 16 biasing the valve body 15 in the valve closing direction. The pressure on the inlet side acts on the pilot valve body 15 through the inlet pressure communication passage 20. A pilot valve rod 18 is continuously provided on the upper portion of the pilot valve body 15 and is joined to a diaphragm 19 as a pressure receiving response portion via the lower diaphragm retainer 10. Lower chamber 30 of diaphragm 19
The pressure on the outlet side is exerted by the outlet pressure communication passage 31. The upper diaphragm retainer 2 is provided on the upper surface of the diaphragm 19.
A coil spring 22 for pressure setting is arranged via 1. The upper diaphragm retainer 21 and the lower diaphragm retainer 10 are arranged so as to sandwich the diaphragm 19 by screwing.

A through hole 9 is formed in the lower diaphragm retainer 10 to connect the lower chamber 30 and the upper surface of the diaphragm 19. Further, the lower surface chamber 30 is connected to a separate vacuum source (not shown) via the connection port 11. When the vacuum pressure on the outlet 3 side is used as a vacuum source without using a separate vacuum source, the connection port 11 is unnecessary.

In FIG. 2, an upper diaphragm retainer 21 accommodates a piston 12 as a pressure responsive element slidably in the vertical direction. A coil spring 38 is provided between the upper surface of the piston 12 and the upper wall 37 of the upper diaphragm retainer 21.
Install in tension. A through hole 26 is also provided in the center of the piston 12, and an opening / closing valve body 28 is arranged at the upper end of the through hole 26.
The through holes 9 and 26 communicate with each other through the piston lower chamber 36. The piston upper chamber 39 communicates with the upper surface side of the diaphragm 19 through the opening 40. The on-off valve body 28 is equipped with a valve shaft 27 penetrating the central portion of the pressure adjusting screw 23 shown in FIG. The through holes 9 and 26 and the opening 40 form a communication passage that connects the other surface of the diaphragm 19, that is, the upper surface side, to the vacuum source.

In FIG. 1, a substantially cylindrical female screw member 32 is arranged above the coil spring 22, and a pressure adjusting screw 23 is threaded through the center thereof. The pressure adjusting screw 23 is attached to the center of the upper part of the upper casing 33, and the pressure adjusting screw 2
By providing a concave groove in a part of 3 and fitting a retaining ring 25, the pressure adjusting screw 23 is attached so as to be rotatable but not vertically displaced. A guide member 34 is arranged between the female screw member 32 and the upper casing 33, and the female screw member 32 is attached so that it can be displaced in the vertical direction but does not rotate. Coil spring 22 arranged between female screw member 32 and upper diaphragm retainer 21
Are welded at both ends and attached in tension. An urging spring 35 that urges the female screw member 32 downward is arranged above the female screw member 32.

Next, the operation will be described. When the pressure on the outlet 3 side falls below the pressure set by the coil spring 22, the spring load of the coil spring 22 is overcome and the diaphragm 19 is displaced downward. Due to the downward displacement of the diaphragm 19, the pilot valve body 15 is opened via the pilot valve rod 18, and the high-pressure fluid on the inlet 2 side passes through the communication passages 20 and 13 and acts on the upper surface of the piston 7 to cause the piston 7 to move. Displaces downward. Due to the displacement of the piston 7, the main valve body 6 opens and the outlet 3
By replenishing the high pressure fluid on the inlet 2 side to the outlet 3
Side pressure rises to the set pressure. When the set pressure is reached, the pilot valve body 15 closes and the main valve body 6 closes in balance with the spring load that pushes the diaphragm 19 upward.

By rotating the valve shaft 27 to vertically displace it, the piston 12 is also vertically displaced so that the tensile force of the coil spring 38 can be adjusted. By setting the tension of the coil spring 38 to a predetermined value and connecting it to the vacuum source via the through holes 9 and 26, a predetermined vacuum pressure acts on the lower surface of the piston 12. When the degree of vacuum rises to a predetermined value, the piston 12 is displaced downward against the tensile force of the coil spring 38 and the opening / closing valve body 28 separates from the upper end of the through hole 26.
The through hole 26 is provided in the piston upper chamber 39 and the diaphragm 19.
Communicates with the top side. Therefore, the upper surface side of the diaphragm 19 is brought into a predetermined vacuum state by the vacuum source. Diaphragm 19
When the vacuum degree on the upper surface side reaches a predetermined value, the piston 12 is pulled upward by the tensile force of the coil spring 38 and the through hole 26 is blocked. When the degree of vacuum on the upper surface side of the diaphragm 19 decreases and the pressure rises, the piston 12 is displaced downward and the through hole 26 communicates, and the upper surface side of the diaphragm 19 is automatically maintained at a predetermined vacuum pressure.

The predetermined vacuum pressure means, for example, when the working vacuum pressure on the outlet 3 side is 30 to 100 tons or less, if the upper surface side of the diaphragm 19 is maintained at 100 tons or more. Since the vacuum pressure acts on the upper and lower surfaces of 19 to cancel each other, the load applied to the diaphragm 19 becomes smaller by that amount, and the spring load of the coil spring 22 that balances as the load becomes smaller can also be made smaller. it can. If the spring load of the coil spring 22 can be reduced, the spring constant also becomes small, and the displacement amount of the spring, that is, the tension amount in this embodiment can be increased when a predetermined load is applied. Therefore, it is necessary to make a minute change. Therefore, the pressure can be set accurately.

Although the lower chamber 30 of the diaphragm 19 is connected to the vacuum source via the connection port 11 in this embodiment, the upper surface of the diaphragm 19 is connected to the vacuum source via a valve or the like. You can also

[0016]

EFFECTS OF THE INVENTION Since a predetermined vacuum pressure is applied to the other surface side of the pressure receiving and responsive portion by the responsive displacement of the pressure responsive element, it is not necessary to minutely change the length of the pressure setting spring when setting the minute pressure. By eliminating the difficulty, it is possible to accurately set the minute pressure.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of a vacuum pressure reducing valve of the present invention.

FIG. 2 is a partially enlarged sectional view of a diaphragm portion in FIG.

[Explanation of symbols]

 2 Inlet 3 Outlet 5 Valve port 6 Main valve body 7 Piston 9 Through hole 11 Connection port 12 Piston 19 Diaphragm 22 Coil spring 23 Pressure adjusting screw 26 Through hole 27 Valve shaft 28 Open / close valve body 38 Coil spring

Claims (1)

[Claims] 1. A valve opening is provided between an inlet and an outlet, a valve body is arranged facing the valve opening, the valve body is connected to a pressure receiving responsive portion, and the outlet side pressure is applied to one surface of the pressure receiving responsive portion. By connecting a pressure setting spring to the other surface, the pressure receiving responder detects that the pressure on the outlet side has dropped below the set pressure and opens the valve port to supply the fluid on the inlet side to the outlet side. In the pressure reducing valve that maintains the outlet side pressure at the set pressure, a communication passage that connects the other surface side of the pressure receiving response portion and a predetermined vacuum source is formed through the pressure response element, and by the displacement of the pressure response element, A pressure reducing valve for vacuum, characterized in that the other side of the pressure receiving responsive portion and the vacuum source are connected and shut off.