JPH1137336A - Pilot operation type high-speed directional control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of the uncomfortable collision noise even when a position of a spool is switched at a high speed. SOLUTION: When a servo valve is switched to a left side switching position in Fig. the fluid flows from a hydraulic pressure source 6 to the second spring chamber 12 through a servo valve 2 and an oil passage 16, whereby a spool 5 is moved to a right side in Fig. at a high speed. On this occasion, the outflow of the fluid in the first spring chamber 11 is blocked through a check valve mechanism 20, so that it flows out into a tank 9 through a variable throttle 7 through an oil passage 15 and the servo valve 2. When an opening area of the variable throttle 7 is reduced by the movement to the right, of the spool 5, the spool, is decelerated, and further the opening area becomes zero before one edge face 5a of the spool 5 is brought into contact with an inner face 13a of a cover 13, whereby the spool 5 is stopped. Accordingly the generation of the collision noise can be prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a pilot-operated high-speed directional control valve for switching a flow direction of a fluid by driving a pilot valve to move a spool of a spool valve.

[0002]

2. Description of the Related Art Conventionally, a pilot-operated directional switching valve in which a pilot valve and a spool valve are combined as described above is, for example, shown in FIG. This valve uses an electromagnetic switching valve 45 as a pilot valve, and introduces a hydraulic pressure from a hydraulic pressure source 53 into the left or right spring chamber 47 or 48 of the spool valve 40 via the electromagnetic switching valve 45, whereby A driving force is applied to the spool 41.

That is, when no input signal is supplied to the electromagnetic switching valve 45 (current is zero), the electromagnetic switching valve 45 is in the switching position shown in FIG. The spring chamber 47 communicates with the tank 54, and the spring chamber 48 on the right communicates with the hydraulic source 53. Accordingly, in this state, a hydraulic pressure equal to the hydraulic pressure acting on the P port of the spool valve 40 is applied to the electromagnetic switching valve 4.
5 and the left spring chamber 47 communicates with the tank 54 via the electromagnetic switching valve 45, so that the spool 41 is in a state of being moved to the left. The left end surface 41a is stationary with the inner surface of the cover 55 in contact therewith.

In this state, when an input signal is supplied to the electromagnetic switching valve 45 and the electromagnetic switching valve 45 is operated so as to be at the right switching position (straight symbol position) in FIG. A spring chamber 48 on the right side communicates with the source 53 and the tank 54. Therefore, a hydraulic pressure equal to the hydraulic pressure acting on the P port of the spool valve 40 is supplied via the electromagnetic switching valve 45 to the left spring chamber 47.
, And the right spring chamber 48 communicates with the tank 54 via the electromagnetic switching valve 45.
Move to the right with.

[0005] The spool 41 is finally stopped when the right end surface 41 b collides with the inner surface of the cover 56. By moving the spool 41 in this manner, the passage direction of oil (fluid) is switched between the spool 41 and each of the oil passages formed in the body 49.

[0006]

However, such a pilot-operated directional switching valve uses a large-capacity electromagnetic switching valve in order to reduce the time required for switching.
This allows the spool to move at high speed, but the spool stops when it collides with the inner surface of the cover that covers the spool valve. There was a problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has as its object to prevent generation of an unpleasant collision sound even when the position of the spool is switched at a high speed.

[0008]

SUMMARY OF THE INVENTION In order to achieve the above object, the present invention has a spool slidably fitted in a sliding hole formed in a body, and has a first end on one end side of the spool. And a spool valve provided with a second spring chamber on the other end side, and one of the first spring chamber and the second spring chamber of the spool valve is selected as a hydraulic pressure source and the other is selected as a tank. A pilot-operated high-speed directional control valve including a pilot valve for connection in a flexible manner is configured as follows.

That is, the pilot-operated high-speed directional control valve allows the fluid supplied through the pilot valve between the pilot valve and the first spring chamber to flow into the first spring chamber. A check valve mechanism for preventing the flow in the opposite direction is provided, and a variable throttle that connects the first spring chamber to the pilot valve is formed between the spool and the body, and the opening area of the variable throttle is reduced. The one end surface of the spool is configured to become zero before abutting on a fixed wall surface facing the one end surface.

With this arrangement, when the pilot valve is driven so as to supply the hydraulic pressure of the hydraulic source to the second spring chamber of the spool valve, the fluid flows from the hydraulic source into the second spring chamber, thereby causing the spool valve to rotate. Moves at high speed to the first spring chamber side. At this time, since the fluid in the first spring chamber is prevented from flowing out through the check valve mechanism, it flows out via the pilot valve through the variable throttle formed between the spool and the body. .

Then, as the spool continues to move toward the first spring chamber, the opening area of the variable stop becomes a predetermined area. Accordingly, since the flow rate flowing out through the variable throttle is regulated from that time, the spool is decelerated, and the opening area is such that one end surface of the spool on the side of the first spring chamber is fixed to the fixed wall surface opposed thereto. Zero before contact. Therefore, the fluid in the first spring chamber is compressed by the spool, and the speed energy of the spool is converted into pressure energy, so that the spool stops. Therefore, since the spool does not violently collide with the fixed wall surface at a high speed, it is possible to prevent generation of an unpleasant collision sound generated when the spool violently collides.

In the above-mentioned pilot-operated high-speed directional control valve, the fluid supplied through the pilot valve between the pilot valve and the second spring chamber is allowed to flow into the second spring chamber. In addition to providing a check valve mechanism for preventing outflow in the opposite direction, a variable throttle that connects the second spring chamber to the pilot valve is formed between the spool and the body, and the opening area of the variable throttle is set to It is preferable that the other end face becomes zero before coming into contact with a fixed wall face facing the other end face.

With this arrangement, even when the pilot valve is driven to supply the hydraulic pressure of the hydraulic source to the first spring chamber of the spool valve, the spool of the spool valve that moves at high speed is decelerated by the damping action. Can be stopped. That is, when the fluid flows from the hydraulic pressure source into the first spring chamber, the spool moves at a high speed toward the second spring chamber, so that the fluid in the second spring chamber passes only through the variable throttle via the pilot valve. leak.

When the opening of the variable throttle reaches a predetermined area by continuing to move the spool toward the second spring chamber, the flow rate passing through the variable throttle is regulated from that point on. Since the opening area is reduced to zero before the other end surface of the spool on the side of the second spring chamber comes into contact with the fixed wall surface opposed thereto,
Then the spool stops. Therefore, since the spool does not collide with the body violently, it is possible to prevent the collision noise from being generated.

Further, in any of the above pilot operated high-speed directional control valves, the driving of the pilot valve is
A current of 100% flows first, and after the movement of the spool of the spool valve is completed and stopped, 20% of the current that flows first
The current should be reduced to about the same level. Even in such a case, after the movement of the spool is completed and stopped, even if the current to the pilot valve is not continuously supplied at 100%, it is not necessary to keep the current.
%, The spool position can be maintained. Then, since the current change value is reduced in this manner, the switching time for switching the spool position can be shortened accordingly, and the response speed of the valve can be increased. Further, power consumption can be reduced.

[0016]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a schematic diagram showing a pilot operated high-speed directional control valve according to the present invention. This pilot-operated high-speed directional control valve has a spool 5 slidably fitted in a slide hole 4 formed in the body 3, and a first spring chamber 11 is provided on one end surface 5 a side of the spool 5. , A spool valve 1 having a second spring chamber 12 on the other end face 5b side, and one of the first spring chamber 11 and the second spring chamber 12 of the spool valve 1 is connected to the hydraulic pressure source 6 and the other is connected to the other. The servo valve 2 is a pilot valve for selectively connecting to the tank 9.

The spool valve 1 has a servo valve 2 and a first
Of the fluid (oil) supplied from the hydraulic pressure source 6 via the servo valve 2 to the first spring chamber 11
A check valve mechanism 20 is provided to allow the inflow into the valve and prevent the outflow in the opposite direction. In the spool valve 1, a variable throttle 7 is formed between the spool 5 and the body 3 so that the first spring chamber 11 communicates with the servo valve 2 through an oil passage 15 and an opening of the variable throttle 7 is formed. The cover 1 has an area in which one end surface 5a of the spool 5 is a fixed wall surface facing the one end surface 5a.
3 before contacting the inner surface 13a.

Further, the spool valve 1 includes a servo valve 2
Check valve mechanism 30 that allows the fluid supplied via the servo valve 2 to flow into the second spring chamber 12 and prevents the fluid supplied through the servo valve 2 from flowing in the opposite direction.
Is provided. The spool valve 1 is provided with a spool 5
The second spring chamber 12 is connected between the
The variable throttle 8 is formed so as to communicate with the servo valve 2 through the inner surface 14a of the cover 14 which is a fixed wall surface facing the other end surface 5b of the spool 5 to the opening surface of the variable throttle 8.
It is set to zero before touching. In order to prevent the spool 5 from moving to the right in FIG. 1 even if the neutral point is shifted due to a temperature change, the servo valve 2 is set so that the neutral point is 5 to 10% of the rated stroke on the right side in FIG. Are shifted to the cross symbol side.

This pilot operated high speed directional control valve is
As shown in the diagram in FIG. 2, when a control system (not shown) inputs a command signal for driving the servo valve 2 to move the spool 5 of the spool valve 1 rightward in FIG.
% Of the current flows (see FIG. 2). Therefore, the servo valve 2 moves to the left switching position in FIG. Accordingly, the hydraulic pressure source 6 is connected to the second spring chamber 12 of the spool valve 1 by the oil passage 16 via the servo valve 2 and the check valve mechanism 30
, The fluid (oil) flows from the hydraulic pressure source 6 into the second spring chamber 12, and the spool 5 starts moving at high speed to the first spring chamber 11 on the right side in FIG. .

As soon as the spool 5 starts moving, the variable throttle 8 opens, so that the second spring chamber 12 has a variable throttle 8 in addition to the free flow path through the check valve mechanism 30. Two inflow channels into which the fluid flows through 8 are formed. Since the opening area of the inflow passage through the variable throttle 8 gradually increases as the spool 5 moves in the above-described direction, the flow rate of the fluid passing therethrough is not regulated by the variable throttle 8.

On the other hand, the fluid in the first spring chamber 11 is prevented from flowing out through the check valve mechanism 20, so that it passes through the variable throttle 7 formed between the spool 5 and the body 3. From the oil passage 15 to the tank 9 via the servo valve 2.

When the spool 5 continues to move toward the first spring chamber 11, the opening area of the variable stop 7 may become a predetermined area. Since that time, the flow rate passing through the variable throttle 7 is regulated,
Since the spool 5 is gradually decelerated and its opening area becomes zero before the one end surface 5a of the spool 5 on the side of the first spring chamber 11 comes into contact with the inner surface 13a of the cover 13 opposed thereto, the first spring chamber The fluid in 11 is the spool 5
, The speed energy of the spool 5 is converted into pressure energy, and the spool 5 stops. Therefore, since the spool 5 does not violently collide with the inner surface 13a of the cover 13 at a high speed, no harsh collision noise is generated when the violent collision occurs.

In this pilot operated high-speed directional control valve, the servo valve 2 is driven by supplying a current of 100% at first as shown in FIG. 2, and is stopped after the movement of the spool 5 of the spool valve 1 is completed. 20% of the initial current after
The current is reduced to about the same level. in this way,
After the movement of the spool 5 is completed and stopped, even if the current to the pilot valve is set to about 20% of the current flowing first,
It is possible to keep holding the spool 5 at the moved position.

Then, even if the command signal for driving the servo valve 2 is ON as shown in FIG. 2, if the movement of the spool 5 is completed, Since there is no oil movement, the current to servo valve 2 is reduced by 20
Even if the pressure is reduced to about%, the hydraulic pressure is guided to the second spring chamber 12, and the spool 5 is held at the moved position, so that power consumption can be reduced.

The servo valve 2 switches the valve by using a torque motor. When the torque motor is operated, the torque motor is excited. Since the excitation requires an excitation time due to the inductance of the coil, +20% − (− 100%) = 120% compared to when there is a current change of +100% − (− 100%) = 200%.
By reducing the current change value, the excitation time can be shortened and the spool 5 can be switched at a high speed.

On the other hand, in this pilot operated high-speed directional control valve, the position of the servo valve 2 is changed in FIG. 1 in a state where the spool 5 is moved to the rightward movement limit in FIG. When the hydraulic pressure source 6 is moved to the right switching position, the hydraulic pressure source 6 is connected to the spool valve 1 by the oil passage 15 via the servo valve 2.
The first spring chamber 11 communicates with the first spring chamber 11 through the check valve mechanism 20.
, And the spool 5 starts moving at high speed toward the second spring chamber 12 on the left side in FIG.

When the spool 5 starts to move to the left in FIG. 1, the variable throttle 7 opens immediately, so that the first spring chamber 11 flows into the first spring chamber 11 via the check valve mechanism 20 in a free flow state. In addition to the paths, two inflow paths are formed because the fluid flows through the variable throttle 7. Since the opening area of the inflow path through the variable throttle 7 increases in accordance with the movement of the spool 5 in the above-described direction, the flow rate of the fluid passing therethrough is not regulated by the variable throttle 7. On the other hand, the fluid in the second spring chamber 12 is prevented from flowing out through the check valve mechanism 30, so that the fluid passes through the variable throttle 8 formed between the spool 5 and the body 3. From 16 flows out to the tank 9 via the servo valve 2.

When the spool 5 continues to move toward the second spring chamber 12, the opening area of the variable stop 8 may become a predetermined area. Since that time, the flow rate passing through the variable throttle 8 will be regulated,
Since the spool 5 is gradually decelerated and its opening area becomes zero before the other end surface 5b of the spool 5 on the side of the second spring chamber 12 comes into contact with the inner surface 14a of the cover 14 opposed thereto, the second spring chamber The fluid in 12 is the spool 5
, The speed energy of the spool 5 is converted into pressure energy, and the spool 5 stops. Therefore, even when the spool 5 moves to the left in this way, the spool 5 does not collide violently with the inner surface 14a of the cover 14 at a high speed. No collision sound is generated.

[0029]

As described above, according to the present invention, it is possible to provide a pilot-operated high-speed directional control valve that does not generate harsh collision noise even when the position of the spool is switched at high speed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a pilot-operated high-speed directional control valve according to the present invention.

FIG. 2 is a timing chart showing a relationship between a command signal to a servo valve of the pilot-operated high-speed directional control valve, a current flowing through the servo valve, and a spool stroke.

FIG. 3 is a configuration diagram showing an example of a conventional pilot-operated directional switching valve in which a pilot valve and a spool valve are combined.

[Explanation of symbols]

 1: Spool valve 2: Servo valve (pilot valve) 3: Body 4: Sliding hole 5: Spool 5a: One end surface 5b: Other end surface 6: Hydraulic power source 7, 8: Variable throttle 9: Tank 11: First spring Chamber 12: Second spring chamber 13, 14: Cover 13a, 14a: Inner surface 20, 30: Check valve mechanism

Claims (3)

[Claims] 1. A spool having a first spring chamber slidably fitted in a slide hole formed in a body, a first spring chamber on one end side of the spool, and a second spring chamber on the other end side. And a pilot valve for selectively connecting one of the first spring chamber and the second spring chamber of the spool valve to a hydraulic pressure source and the other to a tank. A high-speed directional control valve, which allows a fluid supplied via the pilot valve between the pilot valve and the first spring chamber to flow into the first spring chamber, A check valve mechanism for preventing outflow is provided, and a variable throttle that connects the first spring chamber to the pilot valve is formed between the spool and the body;
A pilot-operated high-speed directional control valve, wherein the opening area of the variable throttle is made zero before the one end surface of the spool comes into contact with a fixed wall surface facing the one end surface. 2. The pilot-operated high-speed directional control valve according to claim 1, wherein the second spring chamber of a fluid supplied through the pilot valve between the pilot valve and the second spring chamber. A check valve mechanism for permitting inflow to the valve and preventing outflow in the opposite direction, and a variable throttle that connects the second spring chamber to the pilot valve is formed between the spool and the body. ,
A pilot-operated high-speed directional control valve, wherein an opening area of the variable throttle is made to be zero before the other end surface of the spool comes into contact with a fixed wall surface opposed thereto. 3. The pilot-operated high-speed directional control valve according to claim 1, wherein the driving of the pilot valve comprises:
First, a 100% current is passed, and after the spool valve of the spool valve is completely moved and stopped, the current of 2% of the first current passed.
A pilot operated high speed directional control valve characterized in that the current is reduced to about 0%.