JPH0942503A - Counter balance valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate work for changing internal pilot pressure and external pilot pressure regardless of a change in a load. SOLUTION: A valve plug 9 for opening and closing between passages 3, 4 is provided with a first spring 13 force for setting set pressure by acting in the closing direction between the passages 3, 4, and is also provided with internal pilot pressure based on the back pressure of a load introduced to an internal pilot pressure chamber 17 by facing the first spring 13 force by acting in the opening direction between the passages 3, 4. A piston 16 freely connected to and separated from the valve plug 9 is provided with second spring 19 force and the internal pilot pressure by acting in the withdrawing direction against the valve plug 9 and is also provided with external pilot pressure introduced to an external pilot pressure chamber 21 by facing the second spring 19 force and the internal pilot pressure and by acting in the abutting direction against the valve plug 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a counterbalance valve for controlling back pressure so as to prevent a load from falling.

[0002]

2. Description of the Related Art Conventionally, there is a counterbalance valve of this type as shown in FIGS. 4 and 5 of Japanese Utility Model Laid-Open No. 4-99402. In this device, the pilot pressure is applied to the valve body in opposition to the spring force that sets the set pressure, and the back pressure of the load when the fluid cylinder is lowered is controlled to the set pressure. By selectively attaching and detaching the first plug member and the second plug member to the main body, the pilot pressure acting on the valve body can be freely changed between the external pilot pressure and the internal pilot pressure.

[0003]

However, in such a conventional counterbalance valve, when the internal pilot pressure acts on the valve element and the load is light, the rod side chamber of the fluid cylinder (in this publication, this is set to the rod side chamber). If the pressure of the fluid to be introduced into the valve is not set high, the load will not descend and the operating efficiency will be poor. Also, when the external pilot pressure acts on the valve, if the load is heavy, There is a large pressure difference between the valve body and the hunting that repeats opening and closing of the valve element due to the delay in response of the external pilot pressure that acts on the valve element. The internal pilot pressure and the external pilot pressure must be changed so as to match the weight, and the work of replacing one of the first plug member and the second plug member attached to the valve body with the other There is a problem, which is the debt. The present invention solves such a problem and eliminates the work for changing the internal pilot pressure and the external pilot pressure due to the change of the load, and prevents the decrease in operating efficiency and the occurrence of hunting, which is preferable. A counterbalance valve is provided which is operable.

[0004]

Therefore, according to the present invention, a valve body for opening and closing the flow paths is provided in the main body so as to be slidable in the axial direction, and a set pressure is set in the valve body. The first spring force is provided by acting in the closing direction between the flow paths, and the internal pilot pressure based on the back pressure of the load is provided by acting in the opening direction between the flow paths facing the first spring force. A piston is fitted and inserted into the main body so that it can be moved in and out of contact with the piston and slidably in the axial direction. Is provided so as to oppose the second spring force and the internal pilot pressure in the contact direction with the valve body.

[0005]

In the structure of the present invention, if the load is light and the acting force of the external pilot pressure is larger than the sum of the acting force of the internal pilot pressure based on the back pressure of the load acting on the piston and the second spring force, the piston Is brought into contact with the valve element by the force exerted by the external pilot pressure and presses the valve element in the opening direction between the flow paths against the first spring force, and the back pressure of the load is controlled by the external pilot pressure to reduce the light load. It is possible to prevent a decrease in operating efficiency when operating. Further, the load is changed to a heavy one, and the internal pilot pressure based on the back pressure of the load acting on the piston rises, and the sum of the acting force due to this increased internal pilot pressure and the second spring force acts due to the external pilot pressure. When the force becomes larger than the force, the piston is pressed in the direction of separation from the valve body by the acting force due to the internal pilot pressure and the second spring force, and the valve body acts against the first spring force due to the acting force due to the internal pilot pressure. Pressed in the opening direction, the back pressure of the load is controlled by the internal pilot pressure, and the occurrence of hunting when operating a heavy load can be prevented.
Therefore, when the load is light, the back pressure of the load is controlled by the external pilot pressure, and when the load is heavy, the back pressure of the load is controlled by the internal pilot pressure, and the external pilot pressure and the internal pilot pressure can be changed. Since it can be switched automatically according to the load, the work to change the internal pilot pressure and the external pilot pressure due to the change of the load can be eliminated, and it is possible to prevent the decrease of operating efficiency and the occurrence of hunting and to operate satisfactorily. You can

[0006]

An embodiment of the present invention will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a main body of a counterbalance valve 1A, which is formed in a rectangular parallelepiped shape and has a valve hole 2 formed therein.
To open the flow path 3 and the flow path 4 with a gap in the axial direction,
The flow path 3 is connected to a first flow path 5 that is formed in the direction perpendicular to the paper surface and opens on the lower surface of the main body 1, and the flow path 4 is formed in the direction perpendicular to the paper surface and is formed in the main body. The second flow path 6 having an opening on the upper surface of 1 is connected. Then, as shown in FIG. 2, the first flow path 5 is connected to the head side chamber 7A of the fluid cylinder 7 on which the back pressure based on the weight of the load W acts, and the second flow path 6 is connected to the electromagnetic switching valve 8. ing. Also, the main body 1
2, a supply flow path P, a load flow path A, and a discharge flow path R are provided so as to penetrate in a direction perpendicular to the plane of the drawing and open at the upper and lower surfaces of the main body 1.
As shown in, the supply flow path P is a pressure source P for supplying a pressure fluid.
1 and the electromagnetic switching valve 8 are connected, the load flow path A is connected between the rod side chamber 7B of the fluid cylinder 7 and the electromagnetic switching valve 8, and the discharge flow path R is connected between the low pressure tank T and the electromagnetic switching valve 8. are doing.

Reference numeral 9 denotes a valve element which is slidably inserted in the valve hole 2 in the axial direction. The land portion 9A provided between the openings of the flow paths 3 and 4 to the valve hole 2 connects the flow paths 3 and 4 with each other. Opened and closed, a plurality of notch portions 9B are formed on the outer peripheral surface of the land portion 9A at equal intervals in the circumferential direction, and as the valve body 9 slides in the axial direction, the flow path 3,
It is provided so as to gradually increase the opening degree between four. Reference numeral 10 denotes a spring hole which is connected to one end of the valve hole 2 and which is opened on one side surface of the main body 1. Reference numeral 11 denotes a closing member that closes the opening of the spring hole 10, and is fixedly provided on one side surface of the main body 1 to partition and form a spring chamber 12 inside the spring hole 10. Reference numeral 13 is a first spring for setting a set pressure, which is housed in the spring chamber 12 and provided by applying its own spring 13 force to the valve body 9 in the closing direction between the flow paths 3 and 4. Reference numeral 14 is an adjusting member for adjusting the force of the spring 13 and is provided by being screwed into the closing member 11 so as to be pivotally operable from the outside. 1
Reference numeral 5 denotes a piston hole which is connected to the other end of the valve hole 2 and has a diameter larger than that of the valve hole 2 and is provided on the other side surface of the main body 1. Reference numeral 16 is a piston that is slidably inserted in the piston hole 15 in the axial direction, and is a small-diameter portion 16A having the same diameter as the valve body 9 so that the piston 9 can freely come into contact with and separate from the valve body 9.
Is extended slidably into the valve hole 2.

Reference numeral 17 denotes an internal pilot pressure chamber defined and formed between the other end of the valve body 9 and the tip of the small diameter portion 16A of the piston 16, and a flow passage 3 through a pilot flow passage 18 bored inside the valve body 9. 2, a part of the fluid in the head side chamber 7A of the fluid cylinder 7 shown in FIG. 2 is introduced as an internal pilot fluid. The pressure of the internal pilot fluid introduced into the internal pilot pressure chamber 17 is the internal pilot pressure based on the back pressure of the load W, and the internal pilot pressure is the valve body 9
The first spring 13 is provided so as to face the force of the first spring 13 in the opening direction between the flow paths 3 and 4, and the piston 16 is provided so as to act in the detaching direction from the valve body 9. Reference numeral 19 denotes a second spring accommodated in the piston hole 15, which is provided by applying its own spring 19 force to the piston 16 in the direction of separating from the valve body 9. Reference numeral 20 is a plug member that closes the opening of the piston hole 15, and is fixed to the other side surface of the main body 1 to define an external pilot pressure chamber 21 between it and the end of the piston 16. External pilot pressure chamber 21
Communicates with the load channel A through a pilot channel 22 formed in the main body 1, flows from the supply channel P through the load channel A, and is introduced into the rod side chamber 7B of the fluid cylinder 7 shown in FIG. A part of the pressure fluid is introduced as an external pilot fluid. The pressure of the external pilot fluid introduced into the external pilot pressure chamber 21 is provided as the external pilot pressure in the piston 16 so as to oppose the second spring 19 force and the internal pilot pressure in the contact direction with the valve body 9. 23
Is a non-return valve disposed inside the main body 1 in parallel with the valve body 9 between the flow paths 3 and 4 to make the fluid flow from the flow path 4 to the flow path 3 a free flow and to allow the flow from the flow path 3 to flow. It is provided so as to prevent the fluid flow to the passage 4.

FIG. 2 is a counterbalance valve 1 shown in FIG.
In the operation control circuit diagram of the laminated control device to which A is applied, the check valve 25 and the counter balance valve 1 are provided on the manifold 24.
A is sequentially laminated and the electromagnetic directional control valve 8 is arranged at the uppermost stage. The supply port 8P of the electromagnetic direction switching valve 8 is connected to the pressure source P1 via the supply flow path P of the counterbalance valve 1A, the supply flow path P2 of the check valve 25, and the supply flow path P3 of the manifold 24 to switch the electromagnetic direction. The load port 8A of the valve 8 is connected to the rod side chamber 7B of the fluid cylinder 7 via the load flow path A of the counterbalance valve 1A, the load flow path A1 of the check valve 25, and the load flow path A2 of the manifold 24, and is connected in the electromagnetic direction. The load port 8B of the switching valve 8 is connected to the fluid cylinder 7 via the flow paths 6, 4, 3, 5 of the counterbalance valve 1A, the load flow path B1 of the check valve 25, and the load flow path B2 of the manifold 24.
Connected to the head side chamber 7A of the electromagnetic directional control valve 8 and the discharge port 8R of the electromagnetic directional control valve 8 is of low pressure via the discharge flow path R of the counterbalance valve 1A, the discharge flow path R1 of the check valve 25, and the discharge flow path R2 of the manifold 24. It is connected to the tank T.

The electromagnetic directional control valve 8 has ports 8P, 8A,
Neutral position X that shuts off between 8B and 8R, and supply port 8P
To the load port 8A and to connect the load port 8B to the discharge port 8R for switching communication, and to connect the supply port 8P to the load port 8B and to load port 8A.
With the second switching position Z for switching communication with the discharge port 8R.
It has a position and is provided so as to be switchable to each position X, Y, Z by energization / de-energization. The non-return valve 25 has a non-return valve body 25A therein to allow the fluid flow from the supply flow path P3 side to the supply flow path P side to be a free flow, and from the supply flow path P side to the supply flow path P3 side. It is provided by blocking the fluid flow. The fluid cylinder 7 is provided with a load W movably up and down, and the head side chamber 7A is provided with a back pressure of the load W acting thereon.

Next, the operation of such a configuration will be described. FIG.
Means that the electromagnetic directional control valve 8 is located at the neutral position X and shuts off the ports 8P, 8A, 8B and 8R, the counterbalance valve 1A has the valve body 9 closing the flow passages 3 and 4, and the fluid cylinder 7
Holds the load W in the upper position.

In this state, when the electromagnetic directional control valve 8 is switched to the first switching position Y, the pressure fluid from the pressure source P1 flows through the supply passages P3, P2, P and the load passages A, A1, A2. The fluid in the head side chamber 7A introduced into the rod side chamber 7B of the fluid cylinder 7 and on which the back pressure of the load W acts is the load flow passages B2, B.
1 and the back pressure of the load W is controlled by the counter balance valve 1A to a set pressure set by the force of the first spring 13 and flows through the discharge passages R, R1, R2 and is discharged to the tank T. The load W is lowered. When the load W reaches the lower position in FIG. 2, the electromagnetic directional control valve 8 is switched to the neutral position X and the load W is held at the lower position.

When the electromagnetic directional control valve 8 is switched to the second switching position Z while the load W is held at the lower position, the pressure fluid flowing from the pressure source P1 through the supply passages P3, P2, P becomes second. The check valve 23 of the counterbalance valve 1A flows freely through the flow paths 6 and 4, and flows through the load flow paths B1 and B2 from the flow path 3 and the first flow path 5 into the head side chamber 7A of the fluid cylinder 7. The fluid in the rod side chamber 7B introduced is the load flow path A.
2, A1, A, and discharge passages R, R1, R2 to flow to discharge to the tank T, and the fluid cylinder 7 operates to increase the load W.
When the load W reaches the upper position shown in FIG. 2, the electromagnetic directional control valve 8 is switched to the neutral position X and the load W is held at the upper position.

In the lowering operation of the load W by the fluid cylinder 7, the counter balance valve 1A has a light load W, and the flow passage 3 and the pilot flow passage 18 are connected from the first flow passage 5 connected to the head side chamber 7A of the fluid cylinder 7. Is introduced into the internal pilot pressure chamber 17 via the
Based on the sum of the acting force by the internal pilot pressure based on the back pressure of the load W acting on the A tip and the second spring 19 force, the pressure fluid flowing through the load passage A into the rod side chamber 7B of the fluid cylinder 7 is introduced. When a part of the piston 16 is introduced into the external pilot pressure chamber 21 through the pilot flow passage 22 and the acting force of the external pilot pressure acting on the piston 16 is large, the piston 16 contacts the valve body 9 by the acting force of the external pilot pressure. When the external pilot pressure reaches the set pressure set by the force of the first spring 13, the valve body 9 is pressed against the first spring force 13 to open the flow paths 3 and 4, and the back pressure of the load W is increased. It is controlled by the external pilot pressure to prevent a decrease in operating efficiency when the light load W is lowered.

Further, the load W is changed to a heavy one, and the internal pilot pressure based on the back pressure of the load W acting on the tip of the small diameter portion 16A of the piston 16 increases, and the acting force due to this increased internal pilot pressure and the second The sum of the spring 19 force is
When it becomes larger than the acting force by the external pilot pressure introduced into the external pilot pressure chamber 21 and acting on the piston 16, the piston 16 acts by the acting force by the internal pilot pressure acting on the tip of the small diameter portion 16A and the second spring 19 force. When the internal pilot pressure that is pressed in the direction of separation from 9 and is introduced into the internal pilot pressure chamber 17 and acts on the valve body 9 reaches the set pressure set by the force of the first spring 13, the valve body 9 is moved to the first spring 13 By pressing against the force, the flow paths 3 and 4 are opened, the back pressure of the load W is controlled by the internal pilot pressure, and hunting of the valve body 9 is prevented when the heavy load W is lowered.

For this reason, when the load W that is lowered by the fluid cylinder 7 is light, the valve body 9 is introduced between the flow passages 3 and 4 by the acting force of the external pilot pressure introduced into the external pilot pressure chamber 21 and acting on the piston 16. Press in the opening direction and load W
The back pressure of the valve element 9 is controlled by the external pilot pressure, and when the load W is heavy, the valve element 9 is introduced into the internal pilot pressure chamber 17 and acts on the valve element 9 by the acting force of the internal pilot pressure.
Is pressed in the opening direction between the flow paths 3 and 4 to control the back pressure of the load W by the internal pilot pressure, and the external pilot pressure and the internal pilot pressure can be automatically switched according to the change of the load W. The work for changing the internal pilot pressure and the external pilot pressure due to the change of the load W can be made unnecessary, and it is possible to prevent a decrease in operating efficiency and the occurrence of hunting, and to operate satisfactorily. Further, since the second spring 19 force acts on the piston 16 in the direction of separation from the valve body 9, the switching point for switching between the internal pilot pressure and the external pilot pressure is arbitrarily changed according to the change of the second spring 19 force. Therefore, the internal pilot pressure and the external pilot pressure can be switched at an optimum value according to the application of the load W.

[0017]

As described above, according to the present invention, the valve body for opening and closing the flow paths is provided inside the main body so as to be slidably inserted in the axial direction,
The valve body is provided with a first spring force for setting a set pressure acting in the closing direction between the flow passages, and an internal pilot pressure based on the back pressure of the load is opposed to the first spring force to open the flow passages. The piston is inserted in the main body so that it can be moved in and out of contact with the valve body and slidably in the axial direction. The piston is provided with a second spring force and internal pilot pressure in the direction of separation from the valve body. By providing the external pilot pressure by acting in the contact direction with the valve body in opposition to the second spring force and the internal pilot pressure, the internal pilot pressure and the external pilot pressure due to the change of the load are provided. It is possible to eliminate the work for changing and, and to prevent the decrease in operating efficiency and the occurrence of hunting, so that good operation can be achieved. Further, since the piston is provided with the second spring force acting in the direction of separation from the valve body, the switching point for switching the internal pilot pressure and the external pilot pressure can be arbitrarily changed according to the change of the second spring force.
It has an effect that the internal pilot pressure and the external pilot pressure can be switched at an optimum value according to the load.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of a counterbalance valve showing an embodiment of the present invention.

FIG. 2 is an operation control circuit diagram of a laminated control device to which the counter balance valve shown in FIG. 1 is applied.

[Explanation of symbols]

 1 main body 1A counter balance valve 2 valve hole 3, 4 flow path 9 valve body 13 first spring 16 piston 19 second spring W load

Claims (1)

[Claims] 1. A valve body for opening and closing the flow paths is provided inside the main body so as to be slidable in an axial direction, and a first spring force for setting a set pressure is set on the valve body in a closing direction between the flow paths. The internal pilot pressure based on the back pressure of the load is provided by acting in the opening direction between the flow paths facing the first spring force, and can be slidably moved in and out of contact with the valve body. The piston is fitted into the main body and is provided with the second spring force and the internal pilot pressure acting on the piston in the direction of separating from the valve body, and the external pilot pressure is opposed to the second spring force and the internal pilot pressure. A counterbalance valve that is provided by acting in the contact direction with the valve body.