JPS5920881B2 - Fluid control valve surge pressure prevention circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fluid control valve device that operates a fluid control valve that controls opening of pressure fluid in an operating circuit to a low pressure side.

Conventionally, the operation of a fluid control valve such as a balance piston type relief valve or a pressure reducing valve is performed by opening a vent port 2 in a control chamber of a fluid control valve 1 to a tank 5 on the low pressure side, as shown in FIG. A fixed throttle 3 and a control valve 4 are arranged in series in a connected fluid path 6, and the fluid control valve 1 is operated by shutting off the fluid path 6 by operating the control valve 4.

However, when unloading the fluid control valve 1 by communicating the vent port 2 with the tank 5, back pressure is generated in the vent port 2 by the fixed throttle 3, making it impossible to lower the minimum set pressure of the valve. In addition, when the throttle opening of the fixed throttle 3 is increased, the pressure at the vent port 2 drops rapidly, which generates surge pressure on the tank boat T side of the fluid control valve 1. There is a drawback that when the return pipe 8 or the like is damaged, a large impact sound is generated, causing noise.

The present invention provides a fluid control valve device that eliminates such drawbacks and can perform good operational control of a fluid control valve.One embodiment will be described below with reference to the drawings.

In Fig. 2, 1 is a fluid control valve consisting of a balance piston type relief valve, and a vent port 2 is provided in the control chamber.
A pilot-operated on-off valve A and an operating valve 4 are arranged in series in a fluid path 6 which is open and connected to a tank 5 on the low pressure side.

7 is a tank port of the fluid control valve 1, which is connected to the tank 5 through a return pipe 8.

9 is the valve body of the pilot-operated on-off valve A, and the inflow passage 10
and a small diameter hole 14 having annular grooves 12 and 13 communicating with the outflow passage 11, respectively, and a large diameter hole 15 coaxial with the small diameter hole.
A series of holes of different diameters are provided.

16 is a land portion 17 which is movably inserted into a hole of different diameters.
・A valve body formed with 18 and a spring receiving part 19, and a small diameter hole 14
A valve chamber 20 communicating with the tank 8 is formed on the left side of the land portion 17 in the figure by inserting the land portions 11 and 18 into the large diameter hole 1.
5 is a valve body 9 so as to always urge the valve body 16 to the right in the figure.
A valve chamber 22 in which a spring 21 is inserted is formed between the spring receiving portion 19 and the spring receiving portion 19 .

Reference numeral 23 denotes a cover that is tightly fixed to the side surface of the valve body 9 where the large-diameter hole 15 opens to restrict the end of movement of the valve body 16 to the right in the figure.

A notch groove 24 is formed on the annular groove 12 side of one land portion 18 of the valve body 16 so that the flow area between the inflow passage 10 and the outflow passage 11 can be changed gradually. The valve body 16 is shaped so that it increases as it moves to the right in the figure, and decreases as it moves to the left in the figure.

The outflow passage 11 and the valve chamber 22 are a pilot flow passage 2 provided in parallel.
5 and 26, one pilot flow path 25 is provided with a throttle valve 27 that is screwed onto the valve body 9 and whose opening degree can be freely adjusted, and the other pilot flow path 26 is provided with a flow path from the outflow path 11 to the valve chamber 22. A tip valve 28 is provided to allow the flow of the water and restrict the flow in the opposite direction.

Reference numeral 29 denotes an opening degree adjustment member having a tapered end surface that is screwed into the valve body 9 from the radial direction of the valve chamber 20, and the valve body 1 is adjusted by moving the member back and forth.
6 is for regulating the moving end on the right side in the drawing.

By connecting the inflow passage 10 of the pilot-operated on-off valve A to the vent boat 2 of the relief valve 1, the outflow passage 11 to the shutoff valve 4, and the valve chamber 20 to the return pipe 8, the IJ IJ-F valve is connected. One operation operation circuit is configured.

Next, the operation of the configuration will be explained.

In the state shown in FIG. 2, the relief valve 1 is operated in an unloading manner by the operation valve 4 making the fluid path 6 conductive.

When the operating valve 4 is operated to shut off the fluid path 6 from this state, pressure rises in the fluid path 6 on the vent boat 2 side, and the pressure fluid in the fluid path flows through the pilot flow path 26 and check valve 28 of the valve body 9. It passes through and is introduced into the valve chamber 22.

The valve body 16 is activated by the spring 21 due to the acting force based on the effective pressure-receiving area of the right end surface on which the pressure fluid introduced into the valve chamber 22 acts.
is deflected and moved to the left in the figure, and the inlet passage 10 and the outlet passage 1 are
1 is closed by the land portion 18 of the valve body 16, or communicated with a minute opening adjusted by the opening adjusting member 29.

Therefore, the fluid flow in the vent boat 2 of the fluid control valve 1 disappears or becomes very small, and the fluid control valve operates on-load to control the pressure fluid in the operating circuit to the set pressure.

Next, when the operating valve 4 is operated to conduct the fluid passage 6 to unload the fluid control valve, the pressure inside the valve chamber 22 decreases, and the valve body 16 is moved between the inlet passage 10 and the outlet passage 1 by the spring 21.
Since it is biased toward the right in the figure to increase the flow area between the valve chambers 1 and 1, it moves to the right at a speed corresponding to the fluid discharge speed in the valve chamber 22 controlled by the throttle valve 27.

The flow area between the inflow path 10 and the outflow path 11 gradually increases due to the notched groove 24 formed in the land portion 18 of the valve body 16, and accordingly, the fluid from the fluid path 6 gradually increases and flows into the tank 5. The pressure in the vent boat 2 gradually decreases.

On the other hand, as the pressure of vent port 2 decreases, fluid control valve 1
is activated, and the tank boat 7 is gradually brought into communication with the tank 5. Then, as the valve body 16 comes into contact with the cover 23, the space between the inlet passage 10 and the outlet passage 11 is completely opened, and the vent boat 2 side is opened. The pressure in the fluid path 6 is completely released, and the fluid control valve 1 is operated to unload.

Therefore, during the unloading operation, the tank boat 7 of the fluid control valve 1 is not instantaneously communicated with the tank 5, and generation of surge pressure on the tank boat 7 side is prevented.

The opening adjustment member 29 is used to adjust the initial opening between the inflow passage 10 and the outflow passage 11 during unloading operation, and sets the pressure drop in the fluid passage 6. This adjusts the time required to completely release the pressure, and by adjusting the throttle valve 27 and the opening adjustment member 29, the responsiveness of the unloading operation of the fluid control valve 1 can be adjusted as desired. .

FIG. 3 shows another embodiment of the present invention, in which the same parts as those in FIG. 2 are designated by the same reference numerals, and to avoid duplication, only the parts different from those in FIG. 2 will be described.

In the fluid path 6 of the fluid control valve 1, an operating valve 4 is provided on the upstream side, and a pilot-operated on-off valve A is provided on the downstream side.

Of the valve chambers 20 and 22 formed at both ends of the valve body 16, the valve chamber 22 is connected to the upstream fluid passage 6 of the operating valve 4 and the pilot passage 25.
26, the pressure fluid in the upstream fluid path moves the valve body 16 in a direction that reduces the flow area between the inflow path 10 and the outflow path 11, and the valve chamber 20 is an operating valve. 4
The pressure in the downstream fluid path 6 is introduced through the introduction path 30 to move the valve body 16 in the direction of increasing the flow area.

In operation, when the operation valve 4 is operated to shut off the fluid path 6 from the state shown in FIG. 3, pressure rises in the fluid path upstream of the operation valve 4, and pressure in the downstream fluid path quickly drops.

Therefore, the valve body 16 is activated by the acting force of the pressure fluid of the upstream fluid path introduced into the valve chamber 22 from the pilot flow paths 25 and 26 to prevent the flow between the inflow path 10 and the outflow path 11 formed by the notch groove 24. The fluid control valve 1 is moved in the direction of decreasing the area, and the fluid control valve 1 is operated on-road.

When the operating valve 4 is operated from this state to make the fluid path 6 conductive, the pressures between the upstream and downstream sides of the operating valve 4 become substantially equal, so the pressures within the valve chambers 20 and 22 become substantially equal. , the valve body 16 is moved by the spring 21 in a direction that increases the flow area.

At this time, the amount of fluid discharged from the valve chamber 22 is regulated by the throttle valve 27, and the movement of the valve body 16 is controlled slowly to gradually increase the circulation area, so the pressure in the vent port 2 does not drop suddenly. Gradually descend.

Therefore, the tank port 7 is gradually communicated with the tank 5, thereby preventing surge pressure from being generated on the tank port 7 side.

In this way, the present invention arranges an operating valve and a pilot-operated on-off valve in series in a fluid path that connects the control chamber of a fluid control valve to the low-pressure side, and the pilot-operated on-off valve reduces the flow area of the fluid path. The valve body is formed to be able to change slowly and has a movable valve body, and when the fluid path is blocked by the operation valve, the pressure fluid on the upstream side of the operation valve forces the valve body against the spring and reduces the flow area. At the same time, when the fluid passage is made conductive by the operation valve, the flow rate of the valve body moved by the spring is regulated by the throttle valve, and the moving speed of the valve body is adjustable. By providing the flow to the low pressure side while gradually increasing the flow rate, the flow area of the fluid path connecting the control chamber of the fluid control valve to the low pressure side can be increased or changed to any degree by a simple operation of the operating valve.
The operation of the fluid control valve is gradually controlled in a good manner, and the generation of surge pressure can be reliably prevented, and the fluid path is not constantly throttled with a fixed throttle valve as in the past, and the flow area of the fluid path is set large. As a result, the pressure in the control chamber can be easily lowered, and the minimum set pressure of the fluid control valve can be easily lowered.

In addition, by lowering the minimum set pressure of the fluid control valve, it is possible to minimize power loss in the operating circuit in which the fluid control valve is disposed, and furthermore, by reducing the pressure fluid and spring on the upstream side of the operating valve in the fluid path, Since the valve body of the pilot-operated on-off valve is moved, the amount of movement of the valve body can be set longer than when the valve body is moved using an electromagnet, allowing fine control of the flow area of the fluid path. can be easily obtained.

Moreover, since the amount of discharged pressure fluid is regulated by the throttle valve, it has the advantage that the moving speed of the valve body due to the throttling action of the throttle valve can be stably controlled.

[Brief explanation of drawings]

Fig. 1 is a fluid circuit diagram showing a conventional example of a fluid control valve device, and Fig. 2 is a cross-sectional view of a pilot-operated on-off valve according to the present invention.
FIG. 3 is a fluid circuit diagram showing a second embodiment of the present invention. 1... Fluid control valve, 4... Operation valve, 6
...Fluid path, 16... Valve body, 21...
... Spring, 22 ... Valve chamber, 25 ...
・Pilot flow path, 27... Throttle valve, A...
...Pilot-operated on-off valve.

Claims (1)

[Claims] 1. An operating valve and a pilot-operated on-off valve are arranged in series in a fluid path that connects the control chamber of the fluid control valve to the low pressure side,
The pilot-operated on-off valve has a movable valve body formed so that the flow area of the fluid path can be changed gradually, and when the fluid path is shut off by the operation valve, the pressure fluid on the upstream side of the operation valve The valve body is moved in a direction that reduces the flow area against the spring, and the amount of fluid discharged by the valve body moved by the spring is regulated by a throttle valve when the fluid passage is opened by the operation valve. 1. A fluid control valve device characterized in that the moving speed of the fluid control valve device is adjustable so that fluid from a fluid path is gradually increased and circulated to a low pressure side.