JPH09189371A - Flow control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To simplify the structure and improve accuracy by providing an electric actuator adding the thrust in the normal/reverse direction according to input current, a pilot valve moving a spool based on the thrust, and a spring adjusting opening of the pilot valve according to the movement. SOLUTION: When a current is input in a linear motor 5 by an operation lever, openings of the first and second pilot valves 8, 9 are so adjusted that the thrust of the linear motor 5 produced in compliance with the input current, and the energy storage ability of the first and second energy storage spring 19, 20 storing energy according to movement of the pilot valves 8, 9 and a spool 4 are balanced with each other. As a result, the movement of the spool 4 is fed back to the pilot valves 8, 9 via energy storage spring 19, 20, effects of friction, etc., of the spool 4 on the histeresis is reduced, and the movemnt of the spool 4 is highly accurately controlled according to the manipulated variable. This constitution of moving the spool 4 from the neutral position to the left/right direction and requiring just a linear motor 5 can simplify the constitution of the device.

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 used in various machines such as construction machines used in various construction works and civil works.

[0002]

2. Description of the Related Art Generally, some flow control valves of this type include
The spool movement is configured to be controlled based on the supply of pilot pressure oil to the pilot oil chambers formed on both sides in the spool movement direction, and the supply of pilot pressure oil to the pilot oil chamber is controlled by operating the operation tool. There is a configuration in which a pilot valve such as an electromagnetic proportional control valve electrically controlled based on the above is used.

[0003]

By the way, the flow rate control valve performs output control that is substantially proportional to a signal input based on the operation of the operating tool. However, this has the same input signal value. However, an output deviation due to hysteresis will inevitably occur. Therefore, a feedback method of feeding back the position of the spool to the pilot stage is proposed, but in this case, there is a problem that not only the structure becomes complicated, but also the number of parts increases, and the present invention intends to solve the problem. There was a task to do.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances in order to solve these problems. The spool movement for controlling the flow rate is controlled by the pilot valve. In a flow control valve configured to perform based on the supply of pilot pressure oil corresponding to the opening amount, an electric actuator that can add thrust in forward and reverse directions corresponding to the input current, and the thrust in the forward direction The first pilot valve that supplies pilot pressure oil to move the spool to one side by moving in the opening direction, and the spool moves to the other side in the opening direction based on the thrust in the opposite direction. Therefore, the second pilot valve for supplying the pilot pressure oil and the first pilot valve are accumulated in accordance with the moving amount in the opening direction and the moving amount of the spool accompanying the movement, and the accumulated force is stored. The first bullet adjusts the opening amount of the first pilot valve so as to correspond to the thrust in the positive direction, and the energy is stored according to the movement amount of the second pilot valve in the opening direction and the movement amount of the spool accompanying the movement. , A second bullet that adjusts the opening amount of the second pilot valve so that the stored force corresponds to the thrust in the opposite direction. By doing so, the movement amount of the spool is fed back to the first and second pilot valves via the first and second bullets, and highly accurate flow rate control corresponding to the input current can be performed. At the same time, the electric actuator that operates the first and second pilot valves can be made common, and the number of parts can be reduced and the structure can be simplified. In this configuration, the electric actuator is provided with a movable body that moves by receiving thrust, and the movable body is provided with pressing portions for pressing and moving the first and second pilot valves, respectively. Both pilot valves can be operated separately by one electric actuator. Further, a cylinder cylinder body in which the first and second bullets are internally mounted in series is provided on either the movable body or the spool, and the other is sandwiched between the first and second bullets that are internally mounted. By providing the piston portion that moves in the cylinder cylinder in this state, the movement amount of the spool can be fed back via the first and second bullets.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, embodiments of the present invention will be described with reference to the drawings. In FIG. 1, reference numeral 1 denotes a flow control valve arranged in a pressure oil supply circuit of a hydraulic actuator 2 provided in a construction machine such as a hydraulic excavator, and the flow control valve 1 is axially movable in a valve body 3. The flow rate of the pressure oil supplied from the hydraulic pump P to the expansion side port 2a or the contraction side port 2b of the hydraulic actuator 2 is controlled according to the movement amount of the fitted spool 4. As will be described later, the spool 4 is set so as to be moved by pilot pressure oil supplied corresponding to the thrust of the linear motor 5. The details of the flow rate control of the spool 4 will be omitted.

Reference numerals 6 and 7 denote left and right sleeves assembled on both sides of the valve body 3 in the spool moving direction (left and right direction in FIGS. 1 to 4), and inner sleeve portions 6a and 7a of these sleeves 6 and 7, respectively. Both ends of the spool 4 are movably fitted to the base end side (the side assembled to the valve body 3) of the above. Further, first and second pilot valves 8 and 9 which are movable in the spool movement direction are fitted in series on the tip side of the left sleeve inner tubular portion 6a. These pilot valves 8 and 9 are arranged in series. Is urged outward in the left-right direction by a pilot return bullet 10 interposed between the pilot valves 8 and 9, whereby the pilot valves 8 and
9 is a state in which the linear motor 5 is not energized,
The left end surface portion of the first pilot valve 8 and the right end surface portion of the second pilot valve 9 are respectively locked to the stepped portions 6b and 6c formed in the sleeve inner tubular portion 6a to prevent further movement to the left and right outside. It is located in a neutral position.

The linear motor 5 is housed in a bottomed cylindrical housing 11 assembled to the left side surface of the left sleeve 6, and the linear motor 5 is wound around the inner peripheral surface of the housing 11. It is composed of a coil 12, a plunger 13 that is movable in the left-right direction, and a member such as a permanent magnet 14 that is fixedly attached to the outer peripheral surface of the plunger 13 with a slight gap in the coil 12. Positive and negative currents are input to the coil 12 based on the operation of an operation lever (not shown) operated to expand and contract the hydraulic actuator 2, and the thrust force corresponding to the input current is input. Is added to the plunger 13, whereby the plunger 13 is set so as to move in the left and right directions from the neutral position.

Further, 15 is a push rod whose base end (left end) is provided integrally with the plunger 13, and the push rod 15 is one of the first and second pilot valves 8 and 9. A cylinder cylinder body 16 described later is integrally provided at the tip end through the cylinder portions 8a and 9a. Further, the push rod 15 further includes the first and second pilot valves 8 and 9, respectively. First and second pressing flanges 15a and 15b for locking are formed. When the plunger 13 moves to the right from the neutral position, the first pushing flange 15a of the push rod 15 that moves integrally with the plunger 13 pushes the first pilot valve 8 to the right, thereby Although the one pilot valve 8 moves to the right, the second pressing collar portion 15b does not interfere with the second pilot valve 9, and therefore the second pilot valve 9 is set so as not to move. On the other hand, when the plunger 13 moves to the left, the second pressing flange 15b presses the second pilot valve 9 to move it to the left, but the first pressing flange 15a does not interfere with the first pilot valve 8. For,
The first pilot valve 8 is set so as not to move.

A piston rod 17 projecting into the left sleeve 6 is integrally provided on the left side surface portion of the spool 4, and a piston 18 is fixedly attached to the tip end portion of the piston rod 17. The piston 18 is fitted in the cylinder cylinder 16 at the tip of the push rod 15 so as to be movable in the left-right direction. Furthermore, 19, 20
Are first and second energy storage munitions arranged on both the left and right sides of the piston 18, and these energy storage munitions 19 and 20 are arranged such that the piston 18 moves in the left-right direction from the neutral position with respect to the cylinder cylinder 16. The settings are such that each is stored with a relative movement.

Further, the left sleeve 6 has first and second pilot ports 6d and 6e connected to a pilot hydraulic pressure source 21, and first and second tank ports 6f and 6g connected to an oil tank 22. , And the first and second equalizing ports 6h and 6i are formed. Further, the first pilot oil chamber 23 is on the right side of the spool 4, and the second pilot oil chamber 2 is on the left side of the spool 4.
4 are formed respectively. Furthermore, a third equalizing line port 7b communicating with the first pilot oil chamber 23 is formed in the right sleeve 7, and the third equalizing port 7b and the first and second equalizing portions of the left sleeve 6 are formed. The ports 6h and 6i are connected by an equalizing line 25.

On the other hand, an operating rod 26 projecting into the right side sleeve 7 is integrally provided on the right side surface of the spool 4, and the operating rod 26 is mounted on the right side sleeve 7. Left and right bullet receivers 27
Left and right locking collar portions 26a, which are respectively locked to a and 27b,
26b are formed. And the spool return ammo 27
Is the first or second pilot oil chamber 2 as described later.
When pilot pressure oil is supplied to 3 and 24 and the spool 4 moves in the left-right direction, the locking flange portion 26b or 26a of the operating rod 26 that moves integrally with the spool 4 presses the ammunition receiver 27b or 27a. The spool 4 has the first,
When the supply of the pilot pressure oil to the second pilot chambers 23, 24 is stopped, the spool return ammunition 27 receives the urging force to return to the neutral position.

Next, the first and second pilot valves 8 and 9
2 will be described with reference to FIGS. 2 to 4, first, in a state where the operation lever is not operated, that is, the coil 12 of the linear motor 5 is not energized, the first and second pilot valves 8, 9 is located in the above-mentioned neutral position.
At this time, the pilot ports 6d, 6 of the left sleeve 6
e, the tank ports 6f and 6g, and the second equalizing port 6i are closed by the first and second pilot valves 8 and 9, and the first equalizing port 6h is the first pilot valve 8 The first oil passage 8b formed on the inner side of the inner cylinder portion 8 of the first and second pilot valves 8 and 9.
a, 9a, and an oil passage 9b formed in the second pilot valve 9 communicate with the second pilot oil chamber 24.
In this state, the pilot pressure oil is not supplied to the first and second pilot oil chambers 23 and 24, and the pilot oil chambers 23 and 24 are connected to each other by the third equalizing port 7
b, the equalizing line 25 and the first equalizing port 6h are in communication with each other, and the spool 4 is located at the neutral position (see FIG. 2).

When the operating lever is operated from the neutral state of the spool 4 as described above, a current flows through the coil 12 to move the plunger 13 in either one of the left and right directions. For example, when the plunger 13 moves in the right direction as shown in FIG. In some cases, the first pushing flange 15a of the push rod 15 that moves integrally with the plunger 13 pushes the first pilot valve 8 to move it to the right, whereby the first pilot port 6d and the first equalizing port 6h. The first valve passage 28 that communicates with and opens. Further, at this time, the cylinder tube body 16 at the tip of the push rod 15 also moves to the right side, whereby the first energy storage munition 19 located on the left side of the piston 18 stores energy, and as described later, the linear motor 5 It stops at a position where it opposes (balances) the thrust to move the plunger 13 to the right. In this state, the pilot pressure oil from the pilot hydraulic pressure source 21 is discharged from the first pilot port 6
d, first valve passage 28, first equalizing port 6h, equalizing line 25, third equalizing port 7
It is supplied to the first pilot oil chamber 23 via b. As a result, the spool 4 moves to the left and enters a pressure oil supply state in which pressure oil is supplied to the hydraulic actuator 2, but the piston 18 moving integrally with the spool 4 moves to the left to cause the first storage. Blast machine 19 is further stored. In response to the further stored force of the first storage armor 19, the cylinder body 16 moves to the left together with the push rod 15 and the plunger 13, and accordingly the first pilot valve 8
Also moves to the left, the first pilot valve 8 is moved by the first slammer ammunition 19 as described later.
To the left and the thrust to move the plunger 13 of the linear motor 5 to the right counteracts (balances). Incidentally, the spool 4
Is moved to the left, the oil in the second pilot oil chamber 24 flows to the inner cylinder portions 8a, 9 of the first and second pilot valves 8, 9 respectively.
a, the second oil passage 8c formed in the first pilot valve 8, and the first tank port 6f, and then discharged to the oil tank 22.

Here, the pressure of the pilot pressure oil supplied to the first pilot oil chamber 23 to move the spool 4 to the left is such that the first pilot port 6d communicates with the first equalizing port 6h. The opening amount of the first pilot valve 8 depends on the opening amount of the valve passage 28.
Is smaller toward the left side (the first valve passage 28 is closed when the first pilot valve 8 is located on the leftmost side, that is, in the neutral position), and the first pilot valve 8 is Is set to be larger toward the right side. The opening amount, that is, the position of the first pilot valve 8 is determined by the amount of movement of the spool 4
It is adjusted by being fed back to. That is, when a current is input to the linear motor 5, first, the first pilot valve 8 stores first thrust energy corresponding to the thrust generated in the linear motor 5 and the movement amount of the first pilot valve 8. It moves to the right to a position where the stored force of the ammunition 19 is counteracted, and along with this, as described above, the first valve passage 28 opens and pilot pressure oil is supplied to the first pilot oil chamber 23 to spool. 4 moves to the left, the first storm ammunition 19 is further charged in accordance with the amount of movement of the spool 4 to the left. As a result, the stored force of the first stormograph 19 becomes larger than the thrust of the linear motor 5, and the first pilot valve 8
Will move to the left to a position where the stored force of the first storm ammunition 19 and the thrust of the linear motor 5 antagonize each other. Therefore, the opening amount adjustment of the first pilot valve 8 is controlled by the spool. Four
It is performed in a state of being fed back to the movement amount of. In this case, the urging force of the spool return ammunition 10 also acts on the first pilot valve 8, but since the urging force is weaker than the urging force of the first storming ammunition 19,
It is omitted from the description here.

On the other hand, when the plunger 13 is moved to the left as shown in FIG. 4 based on the operation of the operation lever, the second pushing flange 15b of the push rod 15 pushes the second pilot valve 9 this time. It is moved to the left, so that the second pilot port 6e and the second pilot oil chamber 24
The second valve passage 29 that communicates with and opens, and the cylinder tubular body 16 also moves to the left, whereby the second energy storage munition 20 located on the right side of the piston 18 is charged. In this state, the pilot pressure oil flows into the second pilot port 6e,
It is supplied to the second pilot oil chamber 24 via the second valve passage 29, whereby the spool 4 moves to the right and enters the pressure oil supply state.
By the movement to the right of, the second charging ammunition 20 is further charged. In response to the further energy storage force of the second energy storage munition 20, the cylinder body 16 moves to the right this time, and the second pilot valve 9 also moves to the right accordingly. The movement of the second pilot valve 9 is caused by the force of the second energy storage munitions 20 pressing the plunger 13 to the right and the linear motor 5
When the thrust force that tries to move the plunger 13 to the left opposes (balances), it stops, so that the opening amount adjustment of the second pilot valve 9 is the same as in the case of the first pilot valve 8. It is designed to be fed back to the movement amount of the spool 4. When the spool 4 moves to the right, the first pilot oil chamber 2
The oil of No. 3 is discharged to the oil tank 22 through the third equalizing port 7b, the equalizing line 25, the second equalizing port 6i, and the second tank port 6g.

In the configuration as described above, when a current is input to the linear motor 5 based on the operation of the operating lever, the first and second pilot valves 8 and 9 are generated corresponding to the input current. The thrust of the linear motor 5 and the energizing force of the first and second accumulators 19 and 20 accumulated in correspondence with the movement amounts of the first and second pilot valves 8 and 9 and the spool 4 are The opening amount is adjusted so as to be balanced. As a result, the movement of the spool 4 is caused by the movement of the first and second accumulators 19, 20.
By being fed back to the first and second pilot valves 8 and 9 via, the influence of hysteresis due to friction of the spool 4 is reduced, and the input current, that is, the operation amount of the operating lever, is highly accurate. The movement amount of the spool 4 can be controlled.

As described above, in the embodiment of the present invention, the position of the spool 4 is fed back to the pilot stage for highly accurate control. By inputting a current, forward and reverse thrust is added to the plunger 13,
As a result, either the first pilot valve 8 or the second pilot valve 9 is moved to move the spool 4 from the neutral position to either the left or right direction. As a result, the first, Although the second pilot valves 8 and 9 and the first and second storm ammunition machines 19 and 20 are separately operated, only one linear motor 5 is required, and the number of parts is reduced and the structure is improved. Can be simplified. In the system of the present invention, basically, the current supplied to the linear motor is mechanically proportional to the displacement of the spool by mechanical feedback, but the side of the spool opposite to the side where the linear motor is disposed is arranged. It is also possible to attach a displacement sensor to, for example, to electrically measure the displacement of the spool by the displacement sensor, and to provide an electronic control unit to which the displacement sensor is connected externally to electrically feed back the displacement of the spool. By doing so, it is possible to perform more accurate spool position control.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of a main part at a plunger neutral position.

FIG. 3 is an enlarged view of a main part when the plunger moves rightward.

FIG. 4 is a sectional view when the plunger moves leftward.

[Explanation of symbols]

 1 Flow Control Valve 4 Spool 5 Linear Motor 8 First Pilot Valve 9 Second Pilot Valve 13 Plunger 15 Push Rod 15a First Push Collar 15b Second Push Collar 16 Cylinder Cylindrical 18 Piston 19 First Accumulator 20 Second armor

Claims (3)

[Claims] 1. A flow control valve configured to perform spool movement for flow control based on supply of pilot pressure oil corresponding to an opening amount of a pilot valve,
An electric actuator capable of adding thrust in each of the forward and reverse directions corresponding to the input current, and a pilot pressure oil supply for moving the spool to one side by moving in the opening direction based on the forward thrust. One pilot valve, a second pilot valve that supplies pilot pressure oil to move in the opening direction based on thrust in the opposite direction to move the spool to the other side, and the amount of movement in the opening direction of the first pilot valve and Energy is stored according to the amount of movement of the spool that accompanies the movement, and the first bullet and the second pilot valve that adjust the opening amount of the first pilot valve so that the stored force corresponds to the thrust in the positive direction. A second projectile that stores energy according to the amount of movement in the opening direction and the amount of movement of the spool that accompanies the movement, and that adjusts the opening amount of the second pilot valve so that the accumulated force corresponds to the thrust in the opposite direction. Configured with Flow rate control valve. 2. The electric actuator according to claim 1, wherein the electric actuator includes a movable body that receives a thrust force and moves, and the movable body presses and moves the first and second pilot valves, respectively, in the opening direction. A flow control valve provided with a pressing portion. 3. The cylinder cylinder body for accommodating the first and second ammunition units in series in one of the movable body and the spool, and the other of the first and second interior bodies in the other. , A flow control valve provided with a piston portion that moves in a cylinder cylinder while being sandwiched between second bullets.