JPH0996302A - Flow control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent a flow control valve from vibrating and becoming unstable by influence of a flow force generated in the main oil line. SOLUTION: A flow control valve is composed of a proportional solenoid 5; valve element 7 which moves toward a spool 4 on the basis of an excitation force by the solenoid 5; an elastic compressing elastic member 8, located between the valve element 7 and the spool 4; and a pilot oil supplying device supplying a pilot oil to make the opening of the valve element 7 increased as the valve moves nearer toward the spool 4, and to push the spool against the direction of the excitation force. When the spool 4 is moved owing to the disturbance caused by the flow force, the opening of the pilot oil supply means is changed by the movement of the valve element 7, accompanied by the change in the energizing force of the elastic compressing member by the movement of the spool. The spool moved with the flow force moves, thereby, to the reverse direction by change of supply amount of the pilot oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technical field of a flow control valve arranged in a hydraulic circuit of a construction machine used for various construction works and civil works.

[0002]

2. Description of the Related Art Generally, some flow control valves of this type include
There is a configuration in which the amount of pressure oil supplied to the hydraulic actuator is controlled in accordance with the amount of movement of the spool based on the supply of pilot pressure oil. As such a flow control valve,
Conventionally, the one shown in FIG. 4 is known, but this one receives pilot pressure oil supplied to pilot oil chambers 20 formed on both sides in the moving direction of the spool 4, and receives the pilot pressure oil.
Is configured to move against the biasing force of the compression ammunition 21. In this case, the pilot pressure oil is supplied from a pilot valve, an electromagnetic proportional pressure reducing valve, etc., whose opening is adjusted based on the operation of the operating lever.

[0003]

When an excessive flow force is generated in the main oil passage for supplying pressure oil to the hydraulic actuator, the flow force may act as a disturbance to move the spool. In this case, a load acts on the spool to increase or decrease the urging force of the compression ammunition by receiving the flow force, but the conventional flow control valve does not move the operation lever from the operation position. As long as the pilot pressure does not change, the spool moves under the load based on the flow force, and as a result, the amount of pressure oil supplied to the hydraulic actuator fluctuates, causing vibration. There is a problem in that operability is poor due to instability, and there is a problem to be solved by the present invention.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances in order to solve these problems, and the amount of pressure oil to be supplied to a hydraulic actuator is set to a pilot pressure. In a flow rate control valve configured to control in accordance with the movement amount of a spool based on oil supply, a proportional solenoid whose exciting force is proportionally controlled and a proportional solenoid is pressed by the exciting force of the proportional solenoid to move to a spool side. The valve body, the compression munitions interposed between the valve body and the spool, and the proportional solenoid are closed in the non-excited state, and the opening amount increases as the valve body moves in the spool direction, and the spool is excited. And a pilot oil supply means for supplying pilot pressure oil so as to press in a direction against the force. In this, the pilot oil supply means is
The pilot oil chambers formed at the ends of the spool in the moving direction and the proportional solenoid are closed in the non-excited state, and the opening amount increases as the valve body moves in the spool direction.
It can be constituted by valve means for supplying pilot pressure oil to the pilot oil chamber on the side that presses the spool in the direction against the excitation force. Further, the valve means is open in the de-energized state of the proportional solenoid between the pilot port connected to the pilot hydraulic pressure source, the equalizing line for connecting the pilot oil chambers to each other, and the pilot oil chamber and the equalizing line. In the state, the first valve closed,
The equalizing line and the pilot port can be configured by a second valve passage that is closed in the non-excited state of the proportional solenoid, but in the excited state, the opening amount is adjusted based on the proportional exciting force. Then, when the proportional solenoid is excited by a signal input set corresponding to the control flow rate to the hydraulic actuator, the opening amount of the second valve passage is adjusted so that the first valve passage is moved by the movement of the valve body. Although closed, the second valve passage opens, and as a result, pilot pressure oil is supplied to the pilot oil chamber on the opposite side from the exciting side through the equalizing line, the spool moves to the excited side, and the compression ball is compressed accordingly. This is due to the valve body moving to a position where the urging force of the machine and the exciting force of the proportional solenoid oppose each other. Also, this flow control valve has a tank port connected to the oil tank,
A third valve passage is provided between the tank port and the pilot oil chamber on the proportional solenoid excitation side, which is closed in the non-excited state of the proportional solenoid but opened in the excited state. In this case, when the spool moves due to a disturbance due to a flow force generated on the main oil passage side that supplies pressure oil to the hydraulic actuator, the pilot oil is moved by the movement of the valve element due to the change in the biasing force of the compression ammunition due to the movement of the spool. The amount of opening of the supply means changes, and the change in the supply amount of pilot pressure oil that accompanies this changes acts to move the spool moved by the flow force in the opposite direction. As a result, the movement of the spool due to the flow force is corrected, and the amount of pressure oil supplied to the hydraulic actuator fluctuates due to the influence of the flow force, causing inadvertent vibration or instability. Is prevented and operability is improved.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. In the figure, reference numeral 1 is a flow control valve arranged in a pressure oil supply circuit for a hydraulic actuator 2 provided in a construction machine, and the flow control valve 1 is fitted in a valve body 3 so as to be movable in an axial direction. The opening degree of the valve passage from the hydraulic pump P to the expansion side port 2a or the contraction side port 2b of the hydraulic actuator 2 is adjusted according to the movement amount of the spool 4. As will be described later, it is set so as to be moved by the pilot pressure oil supplied corresponding to the exciting force of the proportional solenoid 5. The description of the adjustment of the opening amount of the spool 4 will be omitted.

Reference numeral 6 designates a pair of left and right sleeves which are assembled on both sides of the valve body 3 in the spool moving direction (horizontal direction in FIGS. 1, 2 and 3). The spool 4 is attached to the valve body 3).
Has an end portion movably fitted thereinto, and a valve body 7 movable in the spool moving direction is fitted to the tip end side of the inner cylinder portion 6a. A compression ammunition machine 8 is interposed between the end and the end.

The proportional solenoid 5 is housed in a housing 9 which is attached to the outer side surface of each sleeve 6 in the left-right direction.
An electromagnet 5a that is excited by an exciting force that is proportional to the operation amount of an operating lever (not shown) that is operated to extend and contract the hydraulic actuator 2, and moves toward the valve body 7 side based on the excitation of the electromagnet 5a. Plunger 5b, the plunger 5
It is composed of a member such as a push rod 5c interposed between the plunger 5b and the valve body 7 so as to move integrally with b. The push rod 5c is set to press the valve body 7 toward the spool 4 side with a pressing force corresponding to the exciting force of the electromagnet 5a based on the operation of the operation lever. 2 and 3, reference numeral 10 denotes a buffer ammunition having a weak thrust interposed between the valve body 7 and the housing 9.

On the other hand, the sleeve 6 is formed with a pilot port 6b connected to the pilot oil pressure source 11, a tank port 6c connected to the oil tank 12, and an equalizing port 6d. The equalizing ports 6d of the sleeve 6 are connected by an equalizing line 13. Further, in the sleeve inner cylinder portion 6a, a pilot oil chamber 14 is formed between the spool 4 and the valve body 7, and a return oil chamber 15 is formed between the valve body 7 and the housing 9. Is a communication hole 7 that connects the pilot oil chamber 14 and the return oil chamber 15 to each other.
a is provided.

Next, the operation of the valve body 7 will be described with reference to FIGS. 2 and 3. When the operating lever is not operated, that is, when the left and right proportional solenoids 5 are not excited, the valve is operated. The body 7 receives the biasing force of the compression ammunition machine 8 and is located closest to the proportional solenoid 5 side. At this time, the sleeve 6
The pilot port 6b and the tank port 6c are closed by the valve body 7, and the first valve passage 16 formed between the equalizing port 6d and the pilot oil chamber 14 is open. In this state, the pilot pressure oil is not supplied to the left and right pilot oil chambers 14, the pilot oil chambers 14 communicate with each other through the equalizing line 13, and the spool 4 is in the neutral state (see FIG. 2). ).

From the non-excited state of the proportional solenoid 5,
For example, when the right proportional solenoid 5 is excited based on the operation of the operating lever, the push rod 5c pushes the right valve body 7 by the movement of the plunger 5b accompanying the excitation, whereby the valve body 7 is compressed by the compression ammunition. 8 is compressed and moved to the left (spool 4 side). This leftward movement of the valve element 7 closes the first valve passage 16 between the equalizing port 6d and the pilot oil chamber 14, and also causes the second valve formed between the pilot port 6b and the equalizing port 6d. The valve passage 17 and the third valve passage 18 formed between the tank port 6c and the return oil chamber 15 are opened (see FIG. 3). In this state, the pilot pressure oil from the pilot hydraulic pressure source 11 flows into the pilot port 6 b of the right sleeve 6.
Is supplied from the equalizing line 13 to the equalizing line 13 via the second valve passage 17 and the equalizing port 6d, and further from the equalizing line 13 via the equalizing port 6d of the left sleeve 6 and the first valve passage 16 to the left pilot oil chamber. 14 are supplied.

When the pilot pressure oil is supplied to the left pilot oil chamber 14, the spool 4 moves to the right to supply pressure oil to the hydraulic actuator 2. The movement of 4 compresses the right compression ammunition machine 8. Further, the valve element 7 moves to the right due to the urging force of the compression ammunition machine 8.
The movement of (1) antagonizes (balances) the force of the compression bullet 8 pushing the valve body 7 to the right and the force of the push rod 5c pushing the valve body 7 to the left by the exciting force of the proportional solenoid 5. By the way, stop. At this time, the oil in the pilot oil chamber 14 on the right side is connected to the communication hole 7a of the valve body 7, the return oil chamber 15,
The oil is discharged to the oil tank 12 side through the third valve passage 18 and the tank port 6c.

The amount of pilot pressure oil supplied to the left pilot oil chamber 14 to move the spool 4 to the right is determined by the second valve passage 17 between the right pilot port 6b and the equalizing port 6d. The opening amount is smaller as the valve body 7 is located on the right side (as described above, when the proportional solenoid 5 is in the non-excited state and the valve body 7 is located on the rightmost side, Valve 1
7 is closed. ), The valve body 7 is set to be larger toward the left side. The amount of opening, that is, the position of the valve body 7 is adjusted according to the exciting force of the proportional solenoid 5. That is, the position of the valve body 7 in the excited state of the proportional solenoid 5 is a position where the urging force of the compression ammunition 8 and the exciting force of the proportional solenoid 5 antagonize (balance) with each other as described above. The larger the exciting force is, the larger the biasing force of the compression ammunition machine 8 that balances with this becomes, but the biasing force of the compression ammunition machine 8 increases in proportion to the amount of movement of the spool 4 to the right. The rightward movement amount of the spool 4 is determined by the pilot pressure supplied to the left pilot oil chamber 14, that is, the opening amount of the second valve passage 17 on the right side as described above. Is increased, the opening amount of the second valve passage 17 is adjusted to be larger. As described above, as the exciting force of the proportional solenoid 5 increases, the opening amount of the right second valve passage 17 increases and the amount of pilot pressure oil supplied to the left pilot oil chamber 14 increases, that is, the spool 4 increases. Therefore, the moving amount of the spool 4 can be adjusted according to the exciting force of the proportional solenoid 5.

In the structure constructed as described above, the moving amount of the spool 4 is adjusted in accordance with the exciting force of the proportional solenoid 5 as described above. When the spool 5 moves to the right due to the disturbance due to the flow force generated on the main oil passage side that supplies the pressure oil to the hydraulic actuator 2 in the pressure oil supply state where the solenoid 5 is excited, the right side of the spool 4 moves with the movement. The biasing force of the compression ammunition machine 8 increases. As a result, the urging force of the compression bullet 8 becomes larger than the exciting force of the proportional solenoid 5, the valve body 7 moves to the right, and the opening amount of the right second valve passage 17 decreases. Along with this, the left pilot oil chamber 1
4, the amount of pilot pressure oil supplied to the spool 4 is reduced, and the spool 4 is moved leftward to offset the rightward movement of the spool 4 due to the flow force. Also,
When the spool 4 is moved leftward due to a disturbance caused by a flow force generated on the main oil passage side in a pressure oil supply state in which the right proportional solenoid 5 is excited, the spool 4 is moved leftward. Along with this, the urging force of the right-side compression ammunition machine 8 decreases. As a result, the valve body 7 moves leftward and the opening amount of the right second valve passage 17 increases. Further, along with this, the supply amount of the pilot pressure oil supplied to the left pilot oil chamber 14 increases, and the spool 4 moves to the right, which offsets the leftward movement of the spool 4 based on the flow force. To be done.

As described above, in the embodiment of the present invention, when the hydraulic oil is supplied to the hydraulic actuator 2, a flow force is generated on the main oil passage side to cause a disturbance in the direction of moving the spool 4. When the spool 4 moves, the amount of pilot pressure oil supplied increases or decreases due to the movement of the valve body 7 that has undergone a change in the urging force of the compression ammunition 8 due to this movement. The spool 4 will move in the opposite direction, which will be offset.

As a result, the movement of the spool 4 due to the flow force is corrected, and the pressure oil supply amount to the hydraulic actuator 2 fluctuates due to the influence of the flow force as in the conventional case, and an unintentional vibration occurs. This prevents the occurrence of instability and instability and improves operability. Besides,
In a state where the operation lever is operated to the neutral position, both pilot oil chambers 14 are in a closed state without communicating with the oil tank 12, but are in a state of communicating with each other through the equalizing line 13. Therefore, the same pressure is applied to the left and right, and the spool 4 is maintained at the neutral position. As a result, there is no malfunction at the time of engine start and the like, and it is possible to prevent the careless operation.

[Brief description of drawings]

FIG. 1 is a sectional view of a flow control valve.

FIG. 2 is an enlarged view of a main part showing a non-excited state of a proportional solenoid.

FIG. 3 is an enlarged view of a main part showing a proportional solenoid excited state.

FIG. 4 is a sectional view of a flow control valve showing a conventional example.

[Explanation of symbols]

 1 Flow Control Valve 2 Hydraulic Actuator 4 Spool 5 Proportional Solenoid 6b Pilot Port 6c Tank Port 7 Valve Body 8 Compressor 11 Pilot Hydraulic Source 13 Equalizing Line 14 Pilot Oil Chamber 16 First Valve Line 17 Second Valve Line 18 Third Valve Road

Claims (6)

[Claims] 1. The amount of pressure oil supplied to the hydraulic actuator is
In a flow rate control valve configured to control a spool movement amount based on the supply of pilot pressure oil, a proportional solenoid whose exciting force is proportionally controlled, and a spool side which is pressed by the exciting force of the proportional solenoid. The valve body that moves to the valve body, the compression ammunition inserted between the valve body and the spool, and the proportional solenoid close in the non-excited state, and the opening amount increases as the valve body moves in the spool direction. Flow control valve configured to include pilot oil supply means for supplying pilot pressure oil to press in a direction opposite to the excitation force. 2. The pilot oil supply means according to claim 1, wherein the pilot oil supply means is closed in a pilot oil chamber formed at each end of the spool in the moving direction, and the proportional solenoid is closed when the proportional solenoid is not excited. A flow control valve including valve means for supplying pilot pressure oil to the pilot oil chamber on the side that presses the spool in a direction that resists the excitation force when the opening amount increases. 3. The valve means according to claim 2, wherein the pilot port is connected to a pilot hydraulic pressure source, and an equalizing line for connecting the pilot oil chambers to each other.
The first valve path that opens between the pilot oil chamber and the equalizing line in the non-excited state of the proportional solenoid, but closes in the excited state, and the area between the equalizing line and the pilot port in the non-excited state of the proportional solenoid, closes in the excited state. A flow control valve constituted by a second valve passage whose opening degree is adjusted based on the proportional exciting force. 4. The adjustment of the opening amount of the second valve passage according to claims 2 and 3, when the proportional solenoid is excited by a signal input set corresponding to a control flow rate to the hydraulic actuator, The movement of the body closes the first valve passage but opens the second valve passage, whereby the pilot pressure oil is supplied to the pilot oil chamber on the side opposite to the one excited by the equalizing line and the spool moves to the excited side. , A flow control valve in which the valve body moves to a position where the biasing force of the compression ammunition that is compressed accordingly and the exciting force of the proportional solenoid are counteracted. 5. The tank port connected to an oil tank and the tank port and the pilot oil chamber on the exciting side of the proportional solenoid are closed in a non-excited state of the proportional solenoid according to claim 2, 3 or 4. A flow control valve provided with a third valve path which is opened in an excited state. 6. The compression according to claim 1, 2, 3, 4 or 5, wherein when the spool moves due to a disturbance caused by a flow force generated on a main oil passage side for supplying pressure oil to the hydraulic actuator, the spool moves. The amount of opening of the pilot oil supply means changes due to the movement of the valve body due to the change in the urging force of the ammunition, and the change in the supply amount of the pilot pressure oil accompanying this causes the spool moved by the flow force to move in the opposite direction. Flow control valve that acts on.