JPH07317933A - Spool type exhaust preventive valve - Google Patents

Abstract

PURPOSE:To improve the flow rate control of a mixing fluid of a liquid and a gas by forming a flow passage between an inlet side valve and a differential pressure operating valve by an outer side attaching trap capillary. CONSTITUTION:A connection pipe 1 to connect an accumulator Acc to a fluid pressure circuit 2 is connected to a tank 107 through a spool type exhaust preventive valve 106. This exhaust preventive valve 106 has a passage 132 to connect an inlet 130 and an outlet 131. The passage 132 is formed of an outside attaching trap tubing (capillary) SK, and a specific amount of liquid is stored in the capillary SK constantly so as to compose it to block the passage of a gas in the tubing. The capillary SK is not necessary to limit in a coil form, but some other form may be used as far as it can exercise the function. And the storing liquid amount can be regulated by converting the coil winding number of the capillary SK. Furthermore, the capillary SK is an outside attaching type, and the storing liquid amount can be detected simply from its length, and the storing amount can be changed simply.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spool type jetting prevention valve used in a hydraulic circuit equipped with an accumulator.

[0002]

2. Description of the Related Art An accumulator is connected to a hydraulic circuit such as an actuator via a connecting pipe. This connecting pipe communicates with the oil drain tank via a pipe with a regulating valve. The accumulator is regularly inspected and maintained in order to maintain its normal function.During this maintenance and inspection, the valve of the connecting pipe is closed to disconnect the communication with the hydraulic circuit, and then the flow rate is adjusted by the adjusting valve. The liquid in the liquid chamber of the accumulator is completely discharged into the tank while adjusting.

This regulating valve controls the flow rate of the liquid discharged into the tank, and it is possible to prevent an abnormally high pressure in the tank due to the flow rate controlling action of this valve, thus preventing the accidental damage of the tank. can do.

[0004] The regulator valve, when only liquid flows,
Due to the throttling effect of the regulating valve, a certain amount of liquid does not flow out.
However, when gas is mixed into the liquid or only gas flows out, for example, when the bladder of the bladder accumulator is damaged and the gas in the gas chamber flows out into the liquid chamber, the atmospheric pressure conversion flow rate increases extremely. However, the tank with low pressure resistance will be damaged. Therefore, in order to solve this problem, a spool type jetting prevention valve as shown in FIG. 10 is used instead of the adjusting valve.

The jetting prevention valve 6 has a primary side chamber 11 and a secondary side chamber 12 when the liquid W flows from the inlet 9 into the flow path 8 and a predetermined amount of the liquid W rapidly passes through the variable throttle section 10. A differential pressure is generated between them, and the pressure in the primary side chamber 11 becomes
It passes through 3 and is transmitted to the back pressure chamber 14. The pressure of the secondary chamber 11 that has received a pressure loss is transmitted to the spring chamber 15 through the passage 16.

When this differential pressure becomes larger than the spring force of the spring 17 which urges in the direction opposite to the arrow A18, the spool 18 moves in the direction of arrow A18, and the variable throttle portion 10 is moved.
Is closed and the supply of the liquid to the tank 7 is stopped. In FIG. 12, 19 is a push pin for adjusting the throttle amount of the spool 14, which is fixed by a lock nut 20.

[0007]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention As shown in FIG.
In the case of the conventional ejection prevention valve, when only the liquid flows, the spool 17 moves in the valve closing direction and the valve closes when the flow rate exceeds a specified amount. However, when gas is mixed in the liquid and becomes a mixed fluid, for example, when the bladder B of the accumulator ACC is damaged and the gas in the gas chamber 21 leaks into the liquid chamber 5, the flow rate increases above the specified amount. However, due to the following reason, the spool 18 does not move in the direction of the arrow A18, which makes it difficult to regulate the flow rate.

Even when the valve 6 is used when gas is mixed in the liquid or only gas flows out, the pressure loss of the gas is smaller than that of the liquid. In the case of a fluid, the differential pressure between the primary side chamber 11 and the secondary side chamber 12 is extremely smaller than that in the case of a liquid alone, which is smaller than the spring force. Therefore, the spool 18 cannot be moved in the valve closing direction.

Since this ejection prevention valve is a spool type valve, even if a necessary amount of liquid is stored in the flow path, the liquid leaks and disappears. Therefore, even if the gas flows out, the spool-type valve does not close, and the function as the ejection preventing valve cannot be exhibited.

Further, in order to store a required amount of liquid in the flow channel, the diameter of the flow channel must be increased in order to increase the volume. However, in this way, the gas in the liquid passes through the valve by hiding the upper part of the liquid, so the amount of liquid required for closing the valve cannot be secured, and the gas flows out and the spool valve closes. The valve does not work and cannot function as an ejection preventive valve.

In view of the above circumstances, an object of the present invention is to make it possible to appropriately control the flow rate even with a mixed fluid of liquid and gas.

[0012]

SUMMARY OF THE INVENTION According to the present invention, a throttle portion whose flow rate is adjusted by an inlet side valve is provided on the inlet side of a flow passage of a valve casing, and a differential pressure actuated valve is provided on the outlet side of the flow passage. A spool-type jetting prevention valve in which a variable throttle portion whose flow rate is automatically adjusted is provided and a spool of the differential pressure operated valve is interlocked with the inlet side valve; the inlet side valve and the differential pressure operated valve; It is intended to achieve the above-mentioned object by forming the flow path between them by the external liquid storage thin tube.

[0013]

When a fluid flows into the inlet of the flow path of the valve housing, the fluid passes through the inlet side throttle portion and reaches the external liquid storage thin tube to press the stored liquid in the thin tube to the variable throttle portion side. While flowing down, it passes through the variable throttle portion and is discharged from the outlet.
When the gas of the mixed fluid passes through the inlet side throttle portion, when the amount of the gas is the same as that of the liquid, the pressure loss of the gas is smaller, so that the flow rate becomes larger than the specified amount.

Therefore, the liquid in the external liquid storage thin tube receives the pressing force of the gas, the liquid pressure increases, and the differential pressure between the primary side and the secondary side in the variable throttle portion also increases. The valve operates in the closing direction to close the variable throttle.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described with reference to FIGS. The accumulator ACC is connected to the hydraulic circuit 2 via a connecting pipe 1. The connecting pipe 1 is connected to the tank 107 via a spool type jetting prevention valve 106.

The jetting prevention valve 106 is provided with a flow path 132 which connects the inlet 130 and the outlet 131. On the inlet 130 side of this flow path 132, a cylindrical inlet side valve 13 is provided.
5 and a cylindrical valve seat 134, the inlet side throttle 13
6 is provided. Further, a variable throttle portion 110 whose flow rate is controlled by a differential pressure actuating valve 118 is provided on the outlet 131 side. The volume of the flow path 132 is within a range in which a predetermined amount of liquid can be stored, that is, a liquid volume that allows the liquid to flow between the time when the differential pressure operating valve 118 is generated and the time when the differential pressure operating valve 118 is closed. It is formed in the range that can hold.

This flow path 132 is formed by a coiled external liquid storage thin tube SK. The predetermined amount of liquid is always stored in the thin tube SK, and the liquid prevents the gas from passing through the tube.

The thin tube SK has a coil shape, but needless to say, may have any shape as long as it has the above-mentioned function. The thin tube SK is formed of, for example, a steel tube having a diameter of 10 mm, and the amount of stored liquid can be appropriately adjusted by changing the number of turns of the coil. Further, since it is an external liquid storage thin tube attached to the outside of the housing 104, the amount of stored liquid can be easily detected from its length. Also, the amount of stored liquid can be easily changed.

One end of the inlet valve 135 is connected to the stopper portion 138 via the connecting portion 137, and the other end is connected to the push rod 140 via the connecting portion 139. The push rod 140 is screwed to a bolt 108 fixed to the housing 104.

The differential pressure operated valve 118 is the inlet side valve 135.
And the central axes of both valves are located on the same straight line C.

The differential pressure operated valve 118 includes a spool 200,
The spring locking portion 145 and the connecting portion 2 for connecting these
01 and. This spool 200 is
The spool 200 is fitted in the cylinder 141, and is in contact with the stopper portion 138 of the inlet valve 135. A back pressure chamber 143 is provided between the stopper portion 138 and the spool 200 of the differential pressure operation valve 118. The back pressure chamber 143 is provided on the primary side F of the differential pressure operation valve 118 via the primary side through hole 144.
It communicates with 2.

In the spring chamber 115, the differential pressure actuated valve 11
A spring 117 for urging the valve 8 toward the inlet valve 135 is provided. This spring chamber 115 is a differential pressure operated valve 1
It communicates with the secondary side S2 through 18 secondary side passages 146.

Next, the operation of this embodiment will be described. First, when the liquid is filled in the thin tube SK and the push rod 140 is rotated to adjust the position of the inlet side valve 135, the spool 200 of the differential pressure actuating valve 118 is pressed by the inlet side valve 135 to move in the direction of arrow A118. It moves and the aperture amount changes.

As described above, the throttle amount of the differential pressure actuated valve 118 is adjusted in conjunction with the primary valve 135, and the flow rate of the variable throttle section 110 is 1 to 1. 1 times the flow rate of the inlet side throttle section 136.
Adjusted to double. It is the inlet side throttle part 1
When the throttle amount of the variable throttle portion 36 is much smaller than that of the variable throttle portion 110, even if the gas passes through the inlet side throttle portion 136, the pressure loss of the variable throttle portion 110 is not so large that the differential pressure actuated valve 118 is moved. Otherwise, in the opposite case, the pressure loss is so large that the differential pressure actuating valve 118 immediately operates and closes.

When the push rod 140 is rotated, the inlet valve is opened, and accordingly, the variable throttle portion 110 is also opened by a specified amount. The liquid W in the accumulator ACC flows into the inlet 130 of the ejection prevention valve 106 and flows from the primary side F1 to the secondary side S1 while the flow rate is adjusted by the inlet side throttle portion 136.

The liquid W that has flowed into the secondary side S1 of the inlet side valve 135 moves toward the variable throttle portion 110 while pressing the liquid stored in the thin tube SK, and the variable throttle portion 11
While adjusting the flow rate at 0, the primary side F of the differential pressure actuated valve 118
2 to the secondary side S2, and is discharged from the outlet 131 into the tank 107. At this time, the primary side F2 of the differential pressure actuated valve 118
A part of the liquid W in the back pressure chamber 14 passes through the primary side through hole 144.
3, the differential pressure actuating valve 118 is pressed in the direction of arrow A118.

The liquid W on the secondary side S2 is transferred to the secondary side passage 146.
After reaching the spring chamber 115, the spring engaging portion 145 is pressed in the direction opposite to the arrow A118.

When the accumulator ACC is arranged vertically, that is, when the gas chamber 21 is located above the liquid chamber 5, the bladder B of the accumulator ACC is damaged and the gas G in the gas chamber 21 is replaced by the gas G. When leaking inside, the fluid W in the liquid chamber 5 is discharged from the inlet / outlet of the accumulator ACC by the expansion force of the pressure gas G due to the specific gravity, and then the pressure gas G flows into the flow path 132 by its own expansion force. Pour in.

That is, when gas is mixed in the fluid discharged from the accumulator ACC, the liquid W is generally discharged before the gas G is discharged.

Therefore, although the gas having a smaller pressure loss than the liquid or a mixture of the gas and the liquid is mixed in the inlet side throttle portion 136 of the ejection preventing valve 106, the mixed fluid starts to flow, and the liquid stored in the thin tube SK in a predetermined amount is It is pressed by the gas fluid or the mixed fluid and flows down the variable throttle unit 110. And the secondary side S1
When a fluid of a prescribed amount or more flows, the pressure of the fluid located on the primary side F2 of the variable throttle portion 110 is rapidly increased by being pressed by the fluid.

Then, the flow rate in the throttle portion increases rapidly, and the differential pressure between the primary side F2 and the secondary side S2 of the variable throttle portion 110 increases. Since this differential pressure becomes larger than the spring force of the spring 117, the differential pressure actuating valve 118 moves away from the inlet side valve 135 in the direction of arrow A118 and closes the variable throttle portion 110.

Therefore, the tank 10 for the liquid W and the gas G is
Since the flow into 7 is stopped, the inside of the tank 107 will not have an abnormally high pressure.

The push rod 140 is rotated to move the inlet side valve 135 to the differential pressure actuating valve 118 side, and the inlet side throttle portion 136 is closed, so that the outflow of the ejection preventing valve 106 can be stopped. Therefore, the ejection preventing valve 106 can also be used as a stop valve.

A second embodiment of the present invention will be described with reference to FIG. 3. The difference between this embodiment and the first embodiment is that the differential pressure actuating valve 118 is provided with a locking means. That is, the notch 224 is engraved on the spool 200 to lock the spool 200 when the differential pressure operated valve 118 is closed, and the spring 222 is pushed to a position opposite to the closed position of the differential pressure operated valve 118. The plunger 221 is installed.

Spool 2 when the differential pressure operating valve 118 is closed
The differential pressure actuated valve 118 is locked by inserting the tip of the plunger 221 into the notch 224 of 00. When the differential pressure actuating valve 118 is actuated, the enclosed gas of the accumulator ACC is discharged from the air supply port, and safety is confirmed and the lock is released. At the time of this release, the lock release rod 223 is pressed from the outside to press the differential pressure actuating valve 118 in the direction opposite to the arrow A118 to remove the notch 224 from the plunger 221. Two
Reference numeral 25 is a spring pressure adjusting screw.

A third embodiment of the present invention will be described with reference to FIGS. 4 and 5. The spool type jetting prevention valve described here is
In addition to the function of the ejection preventive valve, it also functions as a stop valve and a relief valve, and is a so-called combined valve.
The accumulator ACC is connected to the hydraulic circuit 2 via a connecting pipe 1. The connecting pipe 1 is connected to the oil drain tank 107 via the compound valve 506.

The composite valve 506 has an inlet 530 and an outlet 53.
1 is provided with a flow path 532 that communicates with 1. A frustoconical inlet side valve 535 is provided on the inlet 530 side of the flow path 532.
And the inlet side variable throttle portion 5 which is composed of a cylindrical valve seat 534
36 is provided, and on the outlet 531 side, the outlet side variable throttle unit 510 whose flow rate is controlled by the differential pressure operating valve 518.
Is provided. The volume of the flow path 532 can hold a range in which a predetermined amount of liquid can be stored, that is, a liquid volume larger than the liquid flow until the differential pressure operation valve 518 is closed after the differential pressure operation valve 518 is closed. It is formed in the range.

This flow path 532 is an M-shaped external liquid storage thin tube S.
It is formed by K. A predetermined amount of liquid is always stored in the thin tube SK, and the liquid prevents the gas from passing through the tube.

Although the thin tube SK has an M-shape, it is needless to say that it may have any shape as long as it has the above-mentioned function.

The thin tube SK is formed of, for example, a steel tube having a diameter of 10 mm, and the amount of stored liquid can be appropriately adjusted by changing the size of the M-shape or changing the diameter. Further, since it is an external liquid storage thin tube attached to the outside of the housing, the amount of stored liquid can be easily detected from its length. Also, the amount of stored liquid can be easily changed.

One end of the inlet valve 535 is connected to the stopper portion 538 through the connecting portion 537, and the guide portion 537a of the connecting portion 537 is fitted to the cylinder 541.

Since the guide portion 537a is a cylindrical body and is subjected to water pressure in the opposite direction to the inlet side valve 535, the water pressures to the inlet side valve 535 in the same pressure receiving area as the guide portion 537a are mutually different. Canceled.

A ring-shaped fitting groove 535a and a spring locking portion 535b are provided at the other end of the inlet side valve 535. A tip projection 522a of an opening degree adjusting cylinder 522, which is movably provided, is loosely fitted in the fitting groove 535a. The thickness (width) of the tip projection 522a and the width of the groove of the fitting groove 535a are appropriately determined as needed. Further, the valve 535 receives a force opposite to that of the arrow A523 due to the pressing of the spring 517.

At the rear end 522b of the opening adjustment cylinder 522, a spring locking portion 523b is provided at the front end, and a spring locking body 523 having a free connecting portion 523a at the rear end is movably supported. A spring SP for urging the inlet valve 535 in the closing direction is stretched between the spring locking portion 535b and the spring locking portion 523b. The flexible connecting portion 523a is a holding portion 540 of the push rod 540.
supported by a. The push rod 540 is screwed to a bolt 508 fixed to the housing 504.

The differential pressure operating valve 518 is the inlet side valve 535.
And the central axes of both valves are located on the same straight line C.

The differential pressure operating valve 518 includes a spool 600,
It is composed of a spring locking portion / stopper portion 545 and a connecting portion 601 for connecting them. This spool 600 is fitted in the cylinder 541 and
00 is in contact with the stopper portion 538 of the inlet valve 535. A back pressure chamber 543 is provided between the stopper portion 538 and the spool 600 of the differential pressure operation valve 518. The back pressure chamber 543 is provided with the differential pressure operation valve 51 via the primary side through hole 544.
8 to the primary side F2.

In the spring chamber 515, the differential pressure operating valve 51
A spring 517 for urging the valve 8 toward the inlet side valve 535 is provided. This spring chamber 515 has a differential pressure actuating valve 5
It communicates with the secondary side S2 through 18 secondary side passages 546.

Next, the operation of this embodiment will be described. First, when the thin tube SK is filled with the liquid and the push rod 540 is rotated in the direction of arrow A540, the spring locking body 523 moves in the direction of arrow A523 via the pinching portion 540a and presses the spring SP. Therefore, the inlet-side valve 535 moves in the direction of arrow A535 and comes into contact with the valve seat 534, so that the valve is closed. The spring force pressing the inlet valve 535 is appropriately determined as needed.

When the inlet valve 535 is moved, the stopper portion 538 of the inlet valve 535 causes the spool 600 to move in the direction of arrow A.
It is moved in the direction of 518 to close the valve. in this way,
The inlet side valve 535 and the differential pressure operating valve 518 are interlocked with each other, and the differential pressure operating valve 518 is automatically adjusted by adjusting the inlet side valve 535. However, the differential pressure operated valve may not be completely sealed.

The fluid in the hydraulic circuit 2 is the accumulator ACC.
When the bladder B is pushed up and the pressure of the gas chamber 21 rises, the pressure of the spring 517 and the pressure of the connecting pipe 1 rise extremely at this time, and the inlet side valve 535 of the compound valve 506. The primary side F1 becomes larger than the spring force of the spring SP to press the inlet side valve 535 in the direction opposite to the arrow A535, and at the same time, the force of the spring 517 presses the variable throttle valve 518 in the direction opposite to the arrow A518.

Therefore, the inlet side variable throttle portion 536 and the outlet side variable throttle portion 510 are opened, and the state shown in FIG.
The fluid W from the connecting pipe 1 passes through the inlet side variable throttle portion 536 and the outlet side variable throttle portion 510 of the composite valve 506, and the oil drain tank 10
It is discharged to 7. In this embodiment, the inlet valve 535 is a relief valve. Acts as a stop valve. At this time, if the mixed fluid or gas passes through the relief valve, the differential pressure actuation valve 5
18 also opens in conjunction. At this time, the pressure difference in the variable throttle portion of the differential pressure operated valve 518 increases, and the differential pressure operated valve 518 closes.

Next, at the time of maintenance of the accumulator ACC, the push rod 540 is moved to the arrow A540.
When it is rotated in the opposite direction, the valve 535 moves in the direction opposite to the arrow A535 by the tip projection 522a of the cylinder 522 while the spring locking body 523 contacts the opening adjustment cylinder 522. Then, the inlet valve 535 is opened and the differential pressure actuating valve 518 is also opened, and both throttle portions 536 and 510 are in the state shown in FIG. 7.

As described above, the differential pressure actuated valve 518 adjusts the throttle amount in conjunction with the inlet side valve 535, and the flow rate of the outlet side variable throttle portion 510 is 1 to 1 of the flow rates of the inlet side variable throttle portion 536. It is adjusted to be 1.2 times. That is, the throttle amount of the inlet side variable throttle portion 536 is equal to that of the outlet side variable throttle portion 510.
If it is smaller than that, the gas is at the inlet side variable throttle unit 5
Even when passing through 36, since the pressure loss of the outlet side variable throttle portion 510 is not so large, the differential pressure operating valve 518 does not move,
Also, in the opposite case, the pressure loss is so large that the differential pressure operating valve 518 immediately operates and closes.

When the valve 3 is opened after the throttle portion has been adjusted as described above, the liquid W in the accumulator ACC flows into the inlet 530 of the composite valve 506, and the flow rate is adjusted by the inlet side variable throttle portion 536. It flows from the primary side F1 to the secondary side S1.

The liquid W that has flowed into the secondary side S1 of the inlet side valve 535 moves toward the outlet side variable throttle portion 510 while pressing the liquid stored in the thin tube SK, and at the outlet side variable throttle portion 510. Differential pressure operating valve 5 while adjusting the flow rate
18 flows from the primary side F2 to the secondary side S2 and is discharged into the tank 107 from the outlet 531. At this time, the differential pressure operated valve 11
A part of the liquid W on the primary side F2 of 8 reaches the back pressure chamber 543 through the primary side through hole 544 and presses the differential pressure actuating valve 518 in the direction of arrow A518.

The liquid W on the secondary side S2 is transferred to the secondary side passage 546.
After reaching the spring chamber 515, the spring engaging portion 545 is pressed in the direction opposite to the arrow A518.

When the accumulator ACC is arranged vertically, that is, when the gas chamber 21 is located above the liquid chamber 5, the bladder B of the accumulator ACC is damaged and the gas G in the gas chamber 21 is replaced by the gas G. When leaking in, the fluid in the liquid chamber 5 is discharged from the inlet / outlet of the accumulator ACC by the expansion force of the gas G due to the specific gravity, and then the gas G
Flows into the flow path 532 by its own expansion force.

That is, when gas is mixed in the fluid discharged from the accumulator ACC, the liquid W is generally discharged before the gas G is discharged.

Therefore, the gas having a smaller pressure loss than the liquid starts to flow through the inlet side variable throttle portion 536 of the compound valve 506,
The liquid accumulated in the predetermined amount in the thin tube SK is pressed by the gas and flows down the outlet side variable portion 510. And the secondary side S
When a fluid of a prescribed amount or more flows into 1, the pressure of the fluid located on the primary side F2 of the outlet side variable throttle portion 510 is rapidly increased by being pressed by the fluid.

As a result, the flow rate at the throttle portion rapidly increases, and the differential pressure between the primary side F2 and the secondary side S2 of the outlet side variable throttle portion 510 increases. Since this differential pressure becomes larger than the spring force of the spring 517, the differential pressure operating valve 518 moves away from the inlet side valve 535 in the direction of arrow A518 and closes the outlet side variable throttle portion 510, as shown in FIG.

Therefore, the tank 10 for the liquid W and the gas G is
Since the oil discharge to 7 is stopped and the gas G is not discharged, the inside of the oil discharge tank 107 does not have an abnormally high pressure.

The fourth embodiment of the present invention will be described with reference to FIG. 9. The difference from the third embodiment is that the external liquid storage capillary SK is arranged on the lower side of the housing and its shape is It is U-shaped. In FIG. 9, IK is the entrance,
DK is an outlet, CV is a housing of a spool type jetting prevention valve, and F is a floor.

[0063]

Since the present invention is constructed as described above, it has the following remarkable effects. (1) Since the external liquid storage thin tube is provided, a predetermined amount of liquid can be constantly stored in the thin tube, and the length and diameter of the external liquid storage thin tube can be changed. With this, the amount of stored liquid can be easily adjusted. Also, since it is a thin tube, unlike the thick tube, the gas does not leak over the liquid in the tube by leaking from the outlet side valve. Therefore, unlike the conventional example, even if the gas mixed fluid flows into the flow path, the valve is surely closed at an abnormally high pressure.

(2) When the gas or the mixed fluid passes through the throttle portion on the inlet side, the liquid on the primary side of the throttle portion on the outlet side is pressed by the fluid and the hydraulic pressure sharply rises. And the pressure loss increases. Therefore, the differential pressure in the throttle portion becomes large, so that the differential pressure actuating valve moves in the closing direction to close the throttle portion. Therefore, even if gas is mixed with the liquid, there is no fear that the fluid of a specified amount or more is inadvertently ejected. If the spool of the differential pressure actuated valve is provided with appropriate gaps and notches, the fluid under pressure in the accumulator can be appropriately discharged to the tank.

(3) The composite valve is a relief valve / stop valve /
In addition to having the three functions of an ejection prevention valve, a gas or a mixed fluid passes through the inlet side variable throttle portion, the liquid on the primary side of the outlet side variable throttle portion is pressed by the fluid, and the hydraulic pressure rapidly rises. The flow rate in the section rapidly increases and the pressure loss also increases. Therefore, the differential pressure in the throttle portion becomes large, so that the differential pressure actuating valve moves in the closing direction to close the throttle portion. Therefore, even if gas is mixed with the liquid, there is no fear that the fluid of a specified amount or more is inadvertently ejected.

[Brief description of drawings]

FIG. 1 is a schematic view showing a first embodiment of the present invention.

FIG. 2 is an enlarged sectional view of a main part of FIG.

FIG. 3 is a vertical sectional view showing a second embodiment of the present invention.

FIG. 4 is a schematic diagram showing a third embodiment of the present invention.

5 is an enlarged cross-sectional view of the main parts of FIG.

FIG. 6 is a vertical cross-sectional view showing another state of FIG.

7 is a vertical cross-sectional view showing another state of FIG.

8 is a vertical cross-sectional view showing another state of FIG.

FIG. 9 is a schematic diagram showing a fourth embodiment of the present invention.

FIG. 10 is a vertical cross-sectional view showing a conventional example.

[Explanation of symbols]

 104 housing 106 composite valve 110 outlet side variable throttle section 115 spring chamber 117 spring 118 differential pressure actuating valve 130 inlet 131 outlet 132 flow path 134 valve seat 135 inlet side valve 136 inlet side variable throttle section 143 back pressure chamber 144 primary side passage Hole 145 Spring locking portion 146 Secondary passage 504 Housing 506 Composite valve 510 Outlet side variable throttle 515 Spring chamber 517 Spring 518 Differential pressure actuating valve 530 Inlet 531 Outlet 532 Flow passage 534 Valve seat 535 Inlet side valve 536 Inlet side Variable throttle part 543 Back pressure chamber 544 Primary side through hole 545 Spring locking part 546 Secondary side passage F1 Primary side F2 Primary side S1 Secondary side S2 Secondary side SK External liquid reservoir capillary tube

Claims (10)

[Claims] Claim: What is claimed is: 1. A throttle portion, the flow rate of which is adjusted by an inlet side valve, is provided on the inlet side of the flow passage of the valve casing, and the flow rate is automatically adjusted by the differential pressure actuated valve on the outlet side of the flow passage. An ejection preventive valve provided with a variable throttle portion; a spool type ejector preventive valve, characterized in that a flow path between the inlet side valve and the differential pressure actuated valve is formed by an external liquid storage thin tube. . 2. A throttle portion, the flow rate of which is adjusted by an inlet side valve, is provided on the inlet side of the flow passage of the valve casing, and the flow rate is automatically adjusted by the differential pressure actuated valve on the outlet side of the flow passage. A jetting prevention valve, wherein a spool of the differential pressure operated valve is interlocked with the inlet side valve while a variable throttle portion is provided; a flow path between the inlet side valve and the differential pressure operated valve is an external liquid A spool type jetting prevention valve characterized by being formed by a narrow tube. 3. An inlet-side variable throttle having a function of a relief valve and a stop valve is provided on the inlet side of the flow path of the valve housing, and the function of a spool-type jetting prevention valve is provided on the outlet side of the flow path of the valve housing. An ejection preventive valve provided with an outlet side variable throttle section provided therein, characterized in that a flow path between the inlet side variable throttle section and the outlet side variable throttle section is formed by an external liquid storage thin tube. Spool type blowout prevention valve. 4. An outlet side variable throttle portion provided with an inlet side variable throttle portion provided with an inlet side valve on the inlet side of the flow passage of the valve housing and a differential pressure actuated valve provided on the outlet side of the flow passage of the valve casing. The inlet side valve is biased in the closing direction by a spring provided on the push rod and is moved in the opening direction by the backward movement of the push rod through the opening adjusting member, and the differential pressure actuated valve is Has a spool that is urged in the opening direction by a spring provided in the opening side and abuts against the inlet side valve, and a back pressure chamber communicating with the primary side of the valve is provided on the back side of the spool, and the spring chamber is An ejection preventing valve that communicates with a secondary side of the valve via a secondary side passage; a flow path between the inlet side variable throttle section and the outlet side variable throttle section is formed by an external liquid storage thin tube. Spool-type blowout preventive valve characterized by being 5. The external liquid storage thin tube has a liquid volume larger than the amount of liquid flowing until the differential pressure actuating valve is closed. 4. A spool type jetting prevention valve according to 4. 6. The spool type jetting prevention valve according to claim 1, 2, 3 or 4, wherein the external liquid storage thin tube is arranged on the upper side of the valve casing. 7. The spool-type jetting prevention valve according to claim 1, wherein the external liquid storage thin tube is arranged on the lower side of the valve casing. 8. The spool type jetting prevention valve according to claim 1, 2, 3 or 4, wherein the external liquid storage thin tube is formed in a coil shape. 9. The spool type jetting prevention valve according to claim 1, wherein the external liquid storage thin tube is formed in an M shape. 10. The spool type jetting prevention valve according to claim 1, wherein the external liquid storage thin tube is formed in a U shape.