JPH0110520Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Field of Application] This invention relates to an unloader valve that allows a pump to operate continuously by bypassing fluid and returning it to the fluid reservoir when fluid supply is not required.

[Prior Art] This type of unloader valve is widely used in various hydraulic, water pressure, or pneumatic equipment, and when the load side does not require fluid supply, the unloader valve operates to bypass the fluid path and transfer the fluid to an oil tank, etc. This allows the pump to operate continuously with no load.

This type of unloader valve has a first check valve between a pressure fluid inlet connected to the pump side and an outlet connected to the load side, and an unloader valve connected to a water tank, oil tank, etc. A second check valve is interposed between the port and the inlet, and the second check valve is opened by being forcibly pushed by a push rod formed on the piston. It's summery. The piston is configured to receive the pressure on the outlet side on the back side. Therefore, in order to supply fluid to the load side, when the pressure on the outlet side decreases, the first check valve opens and allows the fluid to flow from the inlet to the outlet. When the fluid is no longer needed and the first check valve is closed, the pressure on the outlet side increases and the first check valve is closed. At this time, the pressure on the back side of the piston increases to move the piston forward, and a push rod formed on the piston pushes the second check valve open. Therefore, the inlet side is communicated with the unloading port side, and the pressure fluid pumped from the pump is returned to the water tank or oil tank via the unloading port, resulting in so-called no-load operation.

[The problem that the idea attempts to solve]

However, in such an unloader valve, when the second check valve is open, that is, in the unloaded state, the pressure on the back side of the piston may cause leakage from the seal portion or leakage from the first check valve. may decrease due to Particularly in this state, the pressure on the back side of the piston is relatively high, so the amount of leakage is large. When such a leak occurs, the piston retreats, and the push rod moves away from the second check valve, closing the second check valve.Therefore, the pressure on the inlet side increases, causing the second check valve to close. Open check valve 1 and replenish fluid to the back side of the piston. This replenishment causes the pump to operate under pressure (load). When the pressure on the back side of the piston increases, the second check valve is again pushed open by the push rod, and becomes an unloaded state.

Therefore, this kind of operation is constantly repeated,
In extreme cases, the pump will repeat load and no-load operation within a few seconds, leading to premature pump damage, and the opening and closing frequency of the first and second check valves will also be reduced. Many had the disadvantage of causing early damage.

This idea was devised based on the above circumstances, and its purpose is to reduce the pressure on the back side of the piston even if there is a drop in pressure on the back side of the piston in the unloading state.
An unloader valve that prevents early closing of the check valve of the first check valve, prevents undesired repetition of load-no-load operation of the pump, and reduces the frequency of opening and closing of the first and second check valves, resulting in a longer life. This is what we are trying to provide.

[Means to solve the problem]

The present invention is characterized in that the push rod is separate from the piston, that the push rod is extendable and retractable relative to the piston, and that it is biased by an elastic member in the direction of extension from the piston.

[Effect]

According to the present invention, since the push rod is urged in the direction of extension by the elastic member, even if the piston moves back due to pressure drop on the back side of the piston due to fluid leakage, the push rod is pushed by the elastic member. The second check valve is pressed open and held open. Therefore, undesired closing of the second check valve is prevented, and repeated load-no-load operation of the pump can be reduced.

〔Example〕

An embodiment of the present invention will be described below based on the drawings.

In the figure, 1 is a valve body, and a pressure water inlet 2 is opened at the upper end of the valve body. A pump 3 is connected to the inlet 2, and the pump 3 is driven by a motor 4 to draw up water from the water tank 5 and forcefully send it to the inlet 2.

An outlet port 6 is opened on the left side of the valve body 1 in the drawing. An on-off valve 7 such as a pot or a valve is connected to this outlet 6.

A first valve chamber 8 and a second valve chamber 9 are formed in the valve body 1, and these two valve chambers 8, 9 communicate with each other via a first valve hole 10. The first valve chamber 8 is connected to the outlet port 6, and the second valve chamber 9 is connected to the inlet port 2, so that the inlet port 2 and the outlet port 6 are connected to the first valve hole 10. communicated through.

A first check valve 11 is provided within the first valve chamber 8 . This first check valve 11 has a ball valve 13 slidably attached to a valve holder 12 provided in a valve chamber 8, and this ball valve 13 is pressed and biased by a ball holder 14 and a coil spring 15. The ball valve 13 opens and closes the first valve hole 10. Therefore, the water pressure in the second valve chamber 9 on the inlet 2 side is increased by the water pressure in the first valve chamber 8 on the outlet 6 side.
When the ball valve 13 becomes higher than the biasing force of the coil spring 15, the ball valve 13 opens the first valve hole 10.

On the other hand, a cylinder chamber 16 is formed below the second valve chamber 9 in the drawing, and an unload port 17 is opened on the right side surface of the cylinder chamber 16 in the drawing. The unload port 17 communicates with the water tank 5. A second valve hole 18 is formed between the second valve chamber 9 and the cylinder chamber 16. Therefore, the introduction port 2 and the unload port 17 communicate through this second valve hole 18.

A second check valve 19 is installed within the second valve chamber 9 . This second check valve 19 has the same configuration as the first check valve 11, and a ball valve 21 provided on a valve holder 20 is pressed through a coil spring 22 and a ball retainer 23. The second valve hole 18 is thus closed.

A piston 24 is provided in the cylinder chamber 16 so as to be slidable up and down. A piston rod 25 is projected from the rear side of the piston 24. The lower end of this piston rod 25 is the guide cap 2.
6 in a fluid-tight manner, and a spring receiver 28 is provided at the lower end of this protrusion via an adjustment nut 27. A coil spring 29 is spanned between the spring receiver 28 and the guide cap 26, and this coil spring 29 is connected to the piston 24 via the piston rod 25.
is biased downward as shown in the figure.

The back side of the piston 24 has a communication passage 30.
It is connected to the first valve chamber 8 on the outlet port 6 side via.

A push rod 31 is attached to the front side of the piston 24 so as to be extendable and retractable. This push rod 31 is always given an upward force by a coil spring 32, and its upper end loosely passes through the second valve hole 18 to open the second valve hole 18.
The ball valve 21 of the check valve 19 is in contact with the ball valve 21 of the check valve 19 .

The operation of the unloader valve of the embodiment having such a structure will be explained with reference to FIGS. 2 and 3.

When the pump 3 is activated based on the drive of the motor 4, the pump 3 pumps up water from the water tank 5 and pumps it to the inlet 2 of the unloader valve.

When it is desired to supply water from the outlet 6 side, the on-off valve 7 is opened. Then, the water pressure in the first valve chamber 8 on the outlet port 6 side decreases, so the water pressure on the back side of the piston in the cylinder chamber 16 connected to the first valve chamber 8 also decreases, and thus the piston 24 is lowered. . As a result, the push rod 31 moves far away from the ball valve 21 of the second check valve 19, thereby releasing the ball valve 21. Ball valve 21 thus closes second valve hole 18 . Then, the water pressure in the second valve chamber 9 increases, and this water pressure causes the first check valve 11 to close the valve hole 1.
0 is opened, and as a result, pressurized water from the pump 3 is supplied from the outlet 6 through the inlet 2, the second valve chamber 9, the first valve hole 10, and the first valve chamber 8. This state is shown in FIG. 2, and the pump 3 is in load operation.

Next, when the on-off valve 7 is closed to stop the supply of pressurized water, the water pressure in the first valve chamber 8 increases. Since this valve chamber 8 communicates with the back side of the piston 24, the pressure on the back side of the piston 24 is increased. Therefore, the piston 24 is raised against the coil spring 29. As the piston 24 rises, the push rod 3
1 is also pushed up, and this push rod 31 forcibly pushes up the ball valve 21 of the second check valve 12. The second valve hole 18 is therefore opened. As a result, the second valve chamber 9 communicates with the unload port 17, and the pressure water flowing from the inlet port 2 side is bypassed to the water tank 5 via the unload port 17. Therefore, this state is an unloaded state, and the pump 3 is in a so-called no-load operation, that is, in a dry operation.

Note that in this state, the pressure in the first valve chamber 8 and the pressure in the second valve chamber 8 are
The pressures in the valve chambers 9 of the first check valve 1 become equal, but the pressure in the first check valve 1 becomes equal.
The ball valve 13 in No. 1 is pushed by the coil spring 15 to close the first valve hole 10. This state is the third
As shown in the figure, the water in the first valve chamber 8 is hermetically closed.

Next, when the on-off valve 7 is opened in order to supply pressurized water, the pressure in the first valve chamber 8 decreases as described above, the piston 24 descends, and the second check valve 19 is closed. The first check valve 11 is opened to enter a loaded operating state as shown in FIG.

Therefore, if water leaks from the on-off valve 7, the first check valve 11, or the O-ring of the piston 24 during the no-load operation shown in FIG. The internal pressure gradually decreases. Therefore, the piston 24 is gradually lowered by the urging force of the coil spring 29.

However, the piston 24 has a coil spring 32.
Since the push rod 31 is extendably protruded through the push rod 31, even if the piston 24 is lowered, the push rod 31 continues to push up the ball valve 21 because it is pushed up by the coil spring 32. Therefore, the second check valve 19 is maintained in an open state, that is, the unloaded state continues.

If the unloaded state is continued even when the pressure decreases as described above, the pressure in the first valve chamber 8 will eventually decrease, water leakage will decrease, and the amount of descent of the piston 24 will also decrease. The more you move, the more you can maintain the unloaded state.

That is, according to the above configuration, even if the pressure in the first valve chamber 8 decreases in the unloaded state shown in FIG. 3, the second check valve 19 is not immediately closed, so that the first The frequency with which the stop valve 11 is opened and the pressure water is replenished is reduced, and therefore the number of load operations of the pump 3 during unloading is reduced. In other words, since there is little load operation to replenish the pressure in the first valve chamber 8 during unloading, the pump 3 does not perform load-no-load chattering operation, which prevents failure of the pump 3. be able to. Also, since there is no chattering operation mentioned above, the first
The frequency of opening and closing operations of the check valve 11 and the second check valve 19 is reduced, and wear and tear on these check valves and valve holes can be prevented, resulting in a longer life.

Although the above embodiments have been explained using water, it goes without saying that the present invention can also be implemented using oil.

[Effect of idea]

As detailed above, according to this invention, a telescopic push rod is provided that is biased in the direction of extension with respect to the piston, and this push rod presses the second check valve. Even if the pressure on the back side of the piston decreases in the loaded state, the second check valve is not immediately closed. As a result, the rate at which the pump operates under load in an attempt to replenish pressure on the back side of the piston is reduced, and the pump does not repeat load-no-load operation in a short period of time, which reduces the chance of pump damage or malfunction. Since the opening and closing operations of the first and second check valves are also reduced, there is less wear and tear on these check valves and valve holes, which has the advantage of a longer life.

[Brief explanation of drawings]

The drawings show one embodiment of this invention, with FIG. 1 being a sectional view showing the structure, and FIGS. 2 and 3 being sectional views showing different operating states. 1... Valve body, 2... Inlet, 3... Pump, 6
...Outlet port, 10...First valve hole, 11...First
Check valve, 17...unload port, 18...second
19...Second check valve, 24...Piston, 31...Push rod, 32...Coil spring.

Claims (1)

[Claims for Utility Model Registration] A first non-return check that forms an inlet, an outlet, and an unloading port in the valve body, and allows fluid to flow toward the outlet between the inlet and the outlet. A second check valve is provided between the inlet port and the unloading port, and is opened by being forcibly pushed from the unloading port side to allow fluid to flow from the inlet port toward the unloading port. A piston equipped with a push rod for pressing the second check valve is installed on the unloading port side, and the back side of this piston is communicated with the outlet port to prevent pressure drop on the outlet side. Initially, the first check valve is opened, and the first check valve is closed due to the pressure increase on the outlet side, and pressure is transmitted to the back surface of the piston, causing the piston to open as the second check valve. In the unloader valve, the second check valve is moved to the side and pushed open by a push rod formed on the piston, and the push rod is telescopically connected to the piston and is constantly extended by an elastic biasing member. An unloader valve characterized in that it is biased in a direction to