JPS631899A - Delay control circuit for fluid - Google Patents

Abstract

PURPOSE:To soften the sharp pressure variation by arranging a buffer tank in the feedback passage of a reducing valve. CONSTITUTION:A fluid feeding source 1 is connected with the primary side of a reducing valve 2, and a solenoid valve 4 is installed into a feeding passages 3 on the secondary side 14, and the secondary side of the solenoid valve 4 is branched to a feedback passage 5 and a feeding passage 6. While, the other side is connected with the second chamber 17 of the reducing valve 2 through a filter 7, needle valve 8, and a buffer tank 9. When the valve for the fluid feeding source 1 is opened in the state where the solenoid valve 4 is closed, a pressure P is generated at the point A on the secondary side 14 of the reducing valve 2. Though, when the solenoid valve 4 is opened in this state, the pressure at the B point on the secondary side of the valve 4 immediately becomes P, each pressure rise at the C and D points and in the second chamber 17 of the reducing valve 2 is suppressed by the buffer tank 9 and the restriction of the inflow of gas by the needle valve 8, and the pressure starts to gently increase, and a valve piece 13 starts to open slowly.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a delay control circuit for controlling the opening and closing of a fluid supply valve.

[Prior Art] In a system in which only a solenoid valve is placed in a fluid supply path, when the solenoid valve is opened during fluid supply, the pressure on the supplied side suddenly increases as shown in the characteristic shown in Fig. 3(e). This can cause adverse effects such as disturbance on equipment on the supplied side, and can be dangerous when supplying flammable gas. In order to prevent this, conventional methods have been to provide limit switches at the open and closed positions of the valve opening/closing motor and the opening/closing valve, or to use a servo motor instead of a limit switch to gradually close the opening/closing valve. It was open to the public. Another method used was to gradually open the on-off valve using an air cylinder operated by pneumatic pressure.

[Problem to be Solved by the Invention] When a commuter is used to open and close an on-off valve, a limit switch is used to set the stop position of the on-off valve as described above, but the opening/closing speed of the on-off valve is constant. . In order to vary this speed to the required speed, a speed reducer is required, making the opening/closing control device for the opening/closing valve complicated and expensive. When using a servo motor.

Although the opening and closing speed can be set freely, a control circuit is required to control the servo motor. Similarly, even if an air cylinder operated by pneumatic pressure is used, there are many mechanically moving parts, which causes problems in terms of reliability and lifespan.Moreover, the motor and air cylinder require external energy. Further, if the on-off valve opens slowly at a substantially constant opening/closing speed, there is a problem that it takes too much time for the supplied device to reach the minimum pressure required, making the control system unstable.

[Means for Solving the Problems] In order to solve the above-mentioned problems, the present invention eliminates as many mechanically moving parts as possible, and makes pressure reducing valves, needle valves, on-off valves, buffer tanks, etc. robust and reliable. It is constructed from parts whose properties have been established. That is, an on-off valve and a pressure reducing valve are interposed in a supply path connecting a fluid supply source and a supplied side, and the secondary side of this pressure reducing valve is connected to the pressure reducing valve via a needle valve and a buffer tank. This is what happens.

[Operation] When the on-off valve is opened, the pressure reducing valve is opened by the fluid pressure supplied from the fluid supply source, and the pressure is immediately increased to the minimum pressure required by the supplied device to supply fluid to the secondary side. At this time, the fluid on the secondary side flows into the buffer tank while being regulated by the needle valve, and the pressure in the buffer tank gradually increases. As the pressure in the buffer tank increases, the pressure fed back to the pressure reducing valve also increases, the pressure reducing valve is gradually opened, the pressure on the needle valve also increases, and more fluid flows into the buffer tank. In this way, the pressure within the pressure reducing valve increases until it reaches equilibrium, and when equilibrium is reached, it is supplied at a constant pressure.

[Example code] The present invention will be explained in detail based on FIGS. 1 to 3.

In FIG. 1, (1) is a fluid supply source such as a high-pressure gas cylinder, and this fluid supply source (1) is connected to the primary side of a pressure reducing valve (2). As shown in Fig. 2, this pressure reducing valve (2) has a primary side (12) passing through a valve body (13) and a secondary side (14).
). This secondary side (14) is the supply path (3)
and communicates with the first chamber (16) via the first inlet (15). 2 of this pressure reducing valve (2)
The supply path (3) on the next side (14) is provided with a solenoid valve (4) as an on-off valve, and the secondary side of this solenoid valve (4) is connected to the return path (5) and the supply path (6). Branching out into books, the return path on the negative side (
5) is connected in series with a filter (7), a needle valve (8), and a buffer tank (9).
It is connected to the second inlet (23) of the chamber (17). A supplied device (11) is connected to the other supply path (6) via a needle valve (lO).

Next, the pressure reducing valve (2) has a diaphragm (18) with a first chamber (16) and a second chamber (1) as shown in FIG.
7) is divided, and a valve body (13) is installed on the second chamber (17) side.
) is provided with a spring (19) that urges it in the direction of opening.
The valve body (13) is fixed to the first chamber (16), and an adjustment screw (20) is attached to the upper part of the spring (19).
) is provided so that the pressing force of the spring (19) can be adjusted. Furthermore, there is a cap (21) on the top of the main body.
is airtightly attached with an O-ring (22) in between.

The operation of the present invention with the above configuration will be explained below. First, with the solenoid valve (4) closed, turn on the fluid supply source (1) at 10 o'clock.
When the valve is opened, the secondary side (14) of this pressure reducing valve (2) is opened.
) at point A, the pressure is P, which is adjusted by the adjustment screw (20). If this pressure P is too low, the control system may not be able to follow it;
It is desirable to set it to a high value within a range that does not have a negative effect on As shown in Fig. 3(b), the pressure immediately becomes equal to the pressure P at point A, and this pressure P becomes E through the needle valve (10).
At this point, the pressure of the supplied device (11) becomes P'. Points C and D and the second chamber (1) of the pressure reducing valve (2)
The pressure in step 7) begins to rise slowly as shown in FIG. 3(c) because the inflow of gas is regulated by the needle valve (8) and the rate of pressure rise is suppressed by the buffer tank (9). When the pressure in the second chamber (17) begins to rise, the diaphragm (18) moves down against the pressure in the first chamber (16), and the valve body (13) further opens.
The secondary pressure of the pressure reducing valve (2), that is, the pressure at points A and B increases. In this way, the pressure in this circuit increases and continues to increase until the pressures in the first chamber (16) and the second chamber (17) reach equilibrium.
The pressure at points C and D becomes P and the pressure rise stops. As the pressure at point B gradually increases in this way, the supply pressure at point E to the supplied device (II) increases with the characteristics shown in FIG. 3(d). In the characteristic line shown in Fig. 3(d), the pressure that rises immediately after opening the solenoid valve (4) (life □) is determined by the adjustment screw (20) of the pressure reducing valve (2).
) set by adjustment. In addition, the slope characteristic from T1 to T2 is determined by the opening degree of the needle valve (8) in the buffer tank (
The needle valve (1o), which adjusts the flow rate of the gas flowing into 9), adjusts the final pressure at point E.

In this embodiment, the solenoid valve (4) as an on-off valve is replaced with a pressure reducing valve (
Although the buffer tank (9) is provided on the secondary side of the pressure reducing valve (2), it may also be provided on the primary side of the pressure reducing valve (2).
8) and the pressure reducing valve (2) can be omitted if the return path has the necessary capacity.

[Effects of the Invention] Since the present invention is configured as described above, it is possible to relieve sudden pressure changes due to opening and closing of the on-off valve and open the valve with the desired characteristics, and to reduce the rising pressure to the supplied device without adverse effects caused by high pressure. It can be set freely within a range that does not cause the control system to be unable to follow due to low pressure. In addition, the reliability is high because the component parts used are those that have been established for reliability and durability.
This has the advantage of being able to freely set pressure changes and being inexpensive to manufacture.

[Brief explanation of the drawing]

Fig. 1 is a circuit diagram of an embodiment of the present invention, Fig. 2 is a sectional view of a pressure reducing valve used in the circuit of the present invention, and Fig. 3 is a characteristic diagram showing pressure changes in the circuit shown in Fig. 1. . (1)...Fluid supply source such as high pressure gas cylinder, (2)
...pressure reducing valve, (4) ... solenoid valve, (5) ... return path, (8) ... needle valve, (9) ... buffer tank, (10) ... needle valve , (11)... device to be supplied, (13)... valve body, (15)... first inlet, (16)... first chamber, (17)...
Second chamber, (18)...Diaphragm, (19)
...Spring, (20) ...Adjustment screw, (23)
...Second introduction port.

Claims (3)

[Claims] (1) In a circuit that controls fluid supply by providing an on-off valve in a supply path between a fluid supply source and a supplied device, a pressure reducing valve is interposed in the supply path, and a secondary side of this pressure reducing valve is provided. A fluid delay control circuit characterized in that a pressure reducing valve is connected to a pressure regulating chamber through a needle valve and a buffer tank in a return path that branches off from a supply path. (2) The fluid delay control circuit according to claim 1, wherein the on-off valve is provided on the primary side of the pressure reducing valve. (3) The fluid delay control circuit according to claim 1, wherein the on-off valve is provided on the secondary side of the pressure reducing valve.