JPH05346181A - Pressure compensation type flow control valve - Google Patents

Abstract

PURPOSE:To provide a pressure compensation type flow control valve which can prevent cavitation and the like and has good productivity. CONSTITUTION:A casing 1 is provided with a balance piston 6 facing its both ends to a spring chamber 5 and a pilot chamber 13, and a control orifice 16 to change the opening according to movement of the balance piston 6, a main variable restriction 17 is connected to the lower stream of the pilot chamber 13, and the lower stream of the main variable restriction 17 is connected to the spring chamber 5. This flow control valve is constituted so that an auxiliary pressure chamber 22 to change the volume according to movement of the balance piston 6 is provided, and the auxiliary pressure chamber 22 and the pilot chamber 5 are communicated to each other through a hole 21 formed in the balance piston 6 and maintaining fluid resistance.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pressure compensation device for a flow control valve.

[0002]

2. Description of the Related Art FIG. 3 shows a conventional pressure compensation type flow control valve. This flow control valve has a recess 2 formed in the cover 1,
A sleeve 4 is in contact with the cover 1 via a stopper 3. The stopper 3 has a cylindrical shape and has a space inside. The recess 2, the stopper 3, and the sleeve 4 of the cover 1 form a casing, and a spring chamber 5 is formed inside the casing. A large diameter portion 4a and a small diameter portion 4b are formed inside the sleeve 4, and the boundary between them is a step portion 4c. The balance piston 6 is slidably provided on the small diameter portion 4b.

The balance piston 6 is pushed downward in the figure by the force of springs 7 and 8 provided in the spring chamber 5. A flange 6a is formed on the outer diameter of the end portion of the spring chamber 5 side, and is slid on the large diameter portion 4a.
Further, the inner diameter of the stopper 3 is equal to the large diameter portion 4 of the sleeve 4.
Since it is smaller than a, the flange 6a of the balance piston 6 slides between the stopper 3 and the step portion 4c. Therefore, the sliding range of the balance piston 6 itself slides within the above range.

Further, the flange 6 of the balance piston 6
As a slides on the large diameter portion 4a, a space surrounded by the step portion 4c and the flange 6a is formed. This space serves as an oil sump chamber 9 and is partitioned from the spring chamber 5. As can be seen from the drawing, the oil sump chamber 9 changes its volume in accordance with the movement of the balance piston 6 and is connected to the spring chamber 5 via the second damper orifice 11 and the passage 10 formed in the balance piston 6. It is in communication.

A recess 12 is formed below the balance piston 6 in the drawing, and this recess 12 serves as a pilot chamber 13 for guiding the pressure for moving the balance piston 6. Also, a port 14 is provided in this recess 12.
And the supply port 1 formed on the sleeve 4
It communicates with 5. Port 14 is balance piston 6
Since the balance piston 6 slides in the sleeve 4, the ports 14 and 15 are combined to change the opening area according to the movement of the balance piston 6. Port 14 that acts like this, supply port 1
5 is a control orifice 16, and the flow rate of the pressure oil flowing from the supply port 15 into the pilot chamber 13 is controlled according to the movement of the balance piston 6.

A main variable throttle 17 is connected downstream of the pilot chamber 13. Then, the main variable throttle 17 is branched downstream, one branch passage is connected to an actuator or the like not shown, and the other branch passage 18 is connected to the spring chamber 5 via a first damper orifice 19. Note that reference numeral 20 is an air bleeding member, which serves to release the air generated in the spring chamber 5.

The pressure compensating type flow control valve constructed as described above maintains the differential pressure across the main variable throttle 17 at a set value,
A constant flow rate proportional to the opening of the main variable throttle 17 is always supplied to the actuator or the like. The operation is shown below. Supply port 15 pressure is P _S , main variable throttle 1
7 upstream pressure P ₁ , main variable throttle 17 downstream pressure P
_{2. With} the pressure in the spring chamber 5 being P ₃ , the pressure oil that has flowed in from the supply port 15 at the pressure P _S now passes through the control orifice 16 and the main variable throttle 17 and flows into circuits such as actuators. .. At this time, the main variable aperture 17
The downstream pressure P ₂ is introduced into the spring chamber 5 via the branch passage 18 and the first damper orifice 19. Therefore, when the balance piston 6 stands still, the pressure P ₂ downstream of the main variable throttle 17 and the pressure P ₃ in the spring chamber 5 are equal.

The pressure P ₃ acting in the spring chamber 5
Acts on the surface of the balance piston 6 on the spring chamber 5 side. Due to this pressure, a force is exerted on the balance piston 6 to push it down in the figure. Further, the balance piston 6 is pushed up to the spring chamber 5 side by the pressure P ₁ acting in the pilot chamber 13. In this way, the opposing force acts on the balance piston 6 in the axial direction. When the pressure receiving area of the balance piston 6 is A, there is a relationship of (P ₁ A) = (P ₃ A) + F F: spring force. That is, the spring force F is used to balance the force on the P ₁ side having a high pressure with the force on the P ₃ side having a lower pressure than P ₁ .

When a large load is applied to the actuator or the like in the balance piston 6 in such a balanced state, the pressure upstream of the actuator increases, and the main variable throttle 1
7 The downstream pressure P ₂ also increases. Therefore, the differential pressure before and after the main variable throttle 17 changes. Moreover, since the pressure P ₂ is rising, the pressure P ₃ in the spring chamber 5 is also increased,
The pressure acts on the surface of the balance piston 6 on the spring chamber 5 side. As a result, the balance of the force acting on the balance piston 6 is lost, and the balance piston 6 moves downward in the figure. When the balance piston 6 is moved, the opening area of the control orifice 16 increases, the pressure loss of the pilot chamber 13 is reduced from P _S side.

Therefore, the pressure P ₁ rises, the balance piston 6 is pushed upward in the figure, and the pressures P ₁ , P
Bring the differential pressure between ₂ close to the set value. As the differential pressure approaches the set pressure, the force from the spring chamber 5 side acting on the balance piston 6 (including the force of the pulling 7 and 8 in the figure),
The force from the pilot room 13 side is newly balanced. Then, according to this balance, the control orifice 16
The opening area is also determined, the supply flow rate to the pilot chamber 13 is controlled, and the pressure of P ₁ is also determined. Thus, even if the pressure around the main variable throttle 17 changes, the pressure P
_The balance piston 6 is moved so as to keep the differential pressure between ₁ and P ₂ at the set pressure, and accordingly, the differential pressure between P ₁ and P ₂ is kept constant, and the flow rate passing therethrough is changed to pressure change. I try to keep it constant regardless.

[0011]

In such a conventional pressure compensation type flow control valve, cavitation or the like due to the abrupt movement of the balance piston 6 in the first and second damper orifices 11 and 19 and the oil sump chamber 9 is made. Was prevented. That is, the first damper orifice 19 suppresses the balance piston 6 from rapidly moving toward the spring chamber 5. That is, the oil in the spring chamber 5 tends to flow out from the spring chamber 5 due to the movement of the balance piston 6, but resistance is generated at the first damper orifice 19. As a result, a damping effect against a sudden movement of the balance piston 6 is obtained.

The second damper orifice 11 and the oil sump chamber 9 prevent the balance piston 6 from abruptly moving to the pilot chamber 13 side. That is, the volume of the oil sump chamber 9 is reduced by the force of movement of the balance piston 6, and the oil therein is also compressed. The oil in the oil sump chamber 9 flows into the spring chamber 5 through the passage and the second damper orifice 11, but the amount of the oil flowing into the spring chamber 5 is limited by the second damper orifice 11, so that the oil sump chamber 9 The pressure will increase. This suppresses the sudden movement of the balance piston 6. As described above, the first and second damper orifices 11, 11 and the oil sump chamber 9 are provided to prevent cavitation and the like due to the abrupt movement of the balance piston 6. For this reason, in the case of production, the number of parts is large and the configuration is complicated, so that there is a problem in that processing and assembling are troublesome and productivity is poor. An object of the present invention is to provide a pressure-compensating type flow rate control valve capable of preventing cavitation and the like and having high productivity.

[0013]

In order to solve the above problems, according to the present invention, a balance piston is provided in a casing,
A control orifice that changes the opening according to the movement of the balance piston is provided, and one of the balance pistons faces the spring chamber and the other faces the pilot chamber. In addition to providing a spring for pushing to the pilot chamber, the downstream of the pilot chamber is connected to the main variable throttle, and the balance piston The auxiliary pressure chamber that changes the volume according to the movement of the auxiliary pressure chamber is formed, and the balance piston is formed with a hole for maintaining the flow resistance.The pilot chamber and the auxiliary pressure chamber are communicated with each other through this hole, The pressure is designed to act in the direction in which the balance piston moves against the spring force in the spring chamber. .

[0014]

With the above construction, when the balance piston moves in the acting direction of the spring force of the spring chamber, the pressure in the auxiliary pressure chamber exerts a damper effect. Further, when the balance piston moves against the spring force, the damper effect is exerted by the flow resistance of the fluid flowing into the auxiliary pressure chamber, and the rapid movement of the balance piston is suppressed.

[0015]

1 and 2 show an embodiment of the present invention. The difference from the above-mentioned conventional example is that the first and second damper orifices 19 and 11 are not provided, but instead a hole 21 for maintaining flow resistance is provided in the balance piston 6, and the pilot chamber 13 and the auxiliary chamber 13 are assisted through this hole 21. Pressure chamber 22 (oil sump chamber 9)
And communicate with each other, and other points are the same as in the conventional example. Therefore, the description will be focused on this difference, the same components as those of the conventional example will be denoted by the same reference numerals, and detailed description thereof will be omitted. FIG. 1 shows a first embodiment. Here, similarly to the oil sump chamber 9 of the conventional example, the auxiliary pressure chamber 22 that changes the volume according to the movement of the balance piston 6
Is provided. The auxiliary pressure chamber 22 communicates with the pilot chamber 13 through a hole 21 formed in the balance piston 6 for maintaining flow resistance.

With this structure, when the balance piston 6 suddenly moves to the spring chamber 5 side due to a decrease in pressure downstream of the main variable throttle 17, the volume of the auxiliary pressure chamber 22 also increases accordingly. try to. When the volume is increased, the pressure oil is supplied from the pilot chamber 13 through the hole 21, but due to the flow resistance of the hole 21, the expanded volume of oil cannot be quickly replenished. Therefore, when the volume of the auxiliary pressure chamber 22 is increased, the pressure inside the auxiliary pressure chamber 22 is rapidly reduced. The pressure drop in the auxiliary pressure chamber 22 serves as a force against the force with which the balance piston 6 moves toward the spring chamber 5. This force can prevent the balance piston 6 from abruptly moving to the spring chamber 5 side. Thus, the conventional first damper orifice 19
Is working.

Further, when the pressure downstream of the main variable throttle 17 rises and the balance piston 6 suddenly tries to move to the pilot chamber 13 side, a force acts to reduce the volume of the auxiliary pressure chamber 22. This force causes the oil in the auxiliary pressure chamber 22 to flow into the pilot chamber 13 through the hole 21,
The pressure in the auxiliary pressure chamber 22 increases due to the flow resistance of the hole 21. This pressure produces a damping effect of suppressing the movement of the balance piston 6. This damping effect is achieved by the second damper orifice 11 and the oil sump chamber 9 of the conventional example.

Therefore, if the auxiliary pressure chamber 22 and the pilot chamber 13 are made to communicate with each other through the hole 21 for maintaining the flow resistance, the first and second damper orifices 19 and 11 are formed.
It becomes unnecessary to provide. Further, if the first damper orifice 19 is eliminated, the flow rate is not restricted in the communication between the spring chamber 5 and the main variable throttle 17. Therefore, even if air is mixed into the spring chamber 5, there is no problem, and the air vent member 20 is also removed. No longer need it. As described above, since it is not necessary to provide the first and second damper orifices 19 and 11 and the air bleeding member 20, the number of parts at the time of production can be reduced, the configuration can be simplified, and processing and assembling can be performed. It saves time and improves productivity. Needless to say, the same effect can be obtained even if the auxiliary pressure chamber 22 and the pilot chamber 13 are communicated with each other by using a throttle instead of the hole 21 for maintaining the flow resistance. Further, the damping force can be adjusted by adjusting the flow resistance of the hole 21.

FIG. 2 shows a second embodiment. In the second embodiment, an annular groove 23 is formed in the sliding direction of the balance piston 6. The annular groove 23 is connected to the pilot chamber 26 provided below the balance piston 6 in the drawing and the communication passage 2
It communicates through 4. Further, the sleeve 4 is provided with an outflow port 25. The annular groove 23 and the upstream of the main variable throttle 17 communicate with each other through the outflow port 25.
The supply port 15 and the annular groove 23 form a control orifice 16. Further, the pressure upstream of the main variable throttle 17 acts on the pilot chamber 26, and the balance piston 6
Is pushed upward in the figure. The function and effect are the same as those in the first embodiment.

[0020]

[Effect] Since the auxiliary pressure chamber and the pilot chamber are connected to the balance piston through the hole for maintaining the flow resistance to prevent the balance piston from abruptly moving, for example, the first and second dampers of the related art are used. It is no longer necessary to provide an orifice. Therefore, the number of parts is reduced, the structure is simplified, and the labor for processing and assembling is saved, and the productivity is improved.

[Brief description of drawings]

FIG. 1 is a sectional view of a first embodiment.

FIG. 2 is a sectional view of a second embodiment.

FIG. 3 is a sectional view of a conventional example.

[Explanation of symbols]

 5 Spring Chamber 6 Balance Piston 7, 8 Spring 13 Pilot Chamber 16 Control Orifice 17 Main Variable Throttle 21 Hole 22 Auxiliary Pressure Chamber

Claims (1)

[Claims] 1. A casing is provided with a balance piston and a control orifice whose opening is changed according to the movement of the balance piston, and one of the balance pistons faces a spring chamber and the other faces a pilot chamber. A pressure compensating type in which a spring for pushing the balance piston to the pilot chamber side is provided in the spring chamber, the downstream of the pilot chamber is connected to the main variable throttle, and the downstream of the main variable throttle is communicated with the spring chamber In the flow control valve of, the auxiliary pressure chamber that changes the volume according to the movement of the balance piston is provided, and the balance piston is formed with a hole for maintaining the flow resistance, and the pilot chamber and the auxiliary pressure chamber are connected through this hole. The balance pressure piston against the spring force in the spring chamber. A pressure compensation type flow control valve configured to act in the direction of movement.