JPH09269084A - Directional flow control valve - Google Patents

Abstract

PROBLEM TO BE SOLVED: To compensate for fluid force applied to a spool always effectively. SOLUTION: In a directional flow control valve, fluid force compensating buckets 4, 5 for cancelling the fluid force are formed adjacent to the right and left sides of a land for opening and closing a supply pressure port P, and similarly fluid force compensating buckets 6, 7 are formed adjacent to the land for opening and closing a tank port T, whereby the fluid force generated in the spool axial direction can be cancelled for any direction of a flow of working oil.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fluid force compensation type directional flow control valve.

[0002]

2. Description of the Related Art When a fluid force acts on a spool when a directional flow control valve is switched, a large driving force is required to displace the spool, and the behavior of the spool becomes unstable.

Therefore, conventionally, for example, German Patent No. 292 is used.
A fluid force compensation type directional flow control valve as disclosed in Japanese Patent No. 9352 has been proposed.

To explain this with reference to FIG. 15, a spool 33 is slidably accommodated in a valve hole 32 of a valve body 31. Located around the spool 33, a supply pressure port P, operating ports A and B, and a pair of tank ports T are opened in the valve hole 32, and the spool 33 is driven by a solenoid (not shown) to control switching of each port. It is supposed to do.

Therefore, the land 35 is formed at the center of the spool 33, the lands 36 and 37 are formed on both sides of the spool 33, and the lands 38 and 39 are formed outside the lands 35. As shown in the drawing, the spool 33 is in the neutral position. When it is displaced to the left from, the high-pressure hydraulic oil from the supply pressure port P flows into the port B, and the return oil from the port A flows into the tank port T on the left side.

When the spool 33 is displaced to the opposite side, the supply pressure port P communicates with the operating port A, and the return oil from the operating port B flows to the tank port T on the right side.

When the spool 33 is thus switched and operated, the working oil flows through the orifice formed between each land and the port. At this time, the momentum of the working oil changes, In order to reduce the fluid force acting in the displacement direction of the spool 33, buckets 40 and 41 for fluid force compensation are formed on the spool 33. As shown in the figure, for example, the bucket 40 changes the direction of the hydraulic oil (Qout) flowing out from the operation port A to the tank port T, and a part of the fluid force flowing in and out of the bucket 40 is to the right of the spool 33, and the rest is to the left. By acting in a directional manner and reducing the net fluid force acting on the spool 33, the fluid force that moves the spool 33 in the axial direction is reduced.

[0008]

However, even if the fluid force compensating buckets 40 and 41 are provided and the fluid force exerted on the spool 33 by the fluid flowing from the operation port A to the tank port T is reduced, Also acts on the fluid force by the fluid (Qin) flowing from the supply pressure port P to the operation port B. Even if the shape design of the buckets 40, 41 is performed in anticipation of this amount in advance, the flow rate Qin from the supply pressure port P to the operation port B and the flow rate Qout from the operation port A to the tank port T are not equal, or these If the flow path pressure loss of
Fluid force compensation may be insufficient or overcompensated.

Therefore, particularly when controlling a high pressure and a large flow rate, a large fluid force is generated, a large driving force is required to displace the spool 33, and in some cases, the spool 33 oscillates. There was also the problem of destabilization.

SUMMARY OF THE INVENTION The present invention is intended to solve such a problem, and provides a directional flow control valve capable of always effectively and effectively compensating for a fluid force acting on a spool.

[0011]

A first aspect of the present invention is directed to a spool which is slidably accommodated in a valve body, a supply pressure port P formed in a valve hole around the spool, and an operating port A.
B, left and right tank ports T, and a plurality of lands formed on the spool so as to selectively open and close each of these ports, and the supply pressure port P is set to either the operation port A or B according to the displacement of the spool. At the same time, in the directional flow control valve in which either the other operation port B or A is switched and connected to the tank port T, the fluid force in the spool axis direction is provided adjacent to the left and right of the land for opening and closing the supply pressure port P. The compensating fluid force compensating bucket is formed adjacent to the land for opening and closing the tank port T as well.

In a second aspect based on the first aspect, a slit extending in the axial direction for guiding the flow of hydraulic oil is formed on the outer periphery of the land.

According to a third invention, in the first or second invention, a spring for urging the spool in one direction,
And a land provided so as to close both the operation ports A and B when the spool moves to the limit by a spring.

[0014]

In the first aspect of the invention, the working oil is supplied to the supply pressure port P.
Fluid force in the axial direction of the spool, which is generated when the fluid flows from one of the operation ports A or B to the operation port A or B, is compensated by the action of the fluid force compensating bucket provided adjacent to the land for opening and closing the supply pressure port P. At this time, the hydraulic force of the hydraulic oil flowing out from the other hydraulic oil port B or A to the tank port T is compensated by the hydraulic force compensating bucket provided adjacent to the land for opening and closing the tank port T. As a result, the spool is not subjected to an excessive fluid force by the hydraulic oil flowing in either direction, the driving force required to displace the spool can be reduced, and the behavior of the spool can be stabilized. .

In the second aspect of the invention, the hydraulic oil flows through the slits, the flow can be easily controlled even at a small flow rate, and the operating characteristics of the spool can be stabilized.

In the third aspect of the invention, when the thrust force of the solenoid or the like for driving the spool is stopped, the spool moves in one direction by the urging force of the spring, at which time the operating ports A and B are the supply pressure port P and the tank. It is blocked from any of the ports T. Therefore, the supply / discharge of the hydraulic oil to / from the operation ports A and B is completely stopped, and the fail-safe function at the time of a failure is exhibited.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below. As shown in FIGS. 1 to 4, the spool 3 is slidably accommodated in the valve hole 2 of the valve body 1. Located around the spool 3, the valve hole 2 has an annular supply pressure port P, operating ports A and B, and a pair of tank ports T.
Are opened, and the spool 3 is displaced left and right by a solenoid (not shown), so that each port is switched and controlled.

Therefore, the land 1 is located at the center of the spool 3.
1 is formed, lands 12 and 13 are formed on both sides thereof, lands 14 and 15 are formed on the outer sides thereof, and lands 16 and 17 are formed on the outer sides thereof.

Now, as shown in FIG. 2, when the spool 3 moves from the neutral position to the right in the figure, the high-pressure hydraulic oil from the supply pressure port P flows to the port A, and the return oil from the port B moves to the right side. It flows to the tank port T. Further, when the spool 3 is displaced to the opposite side, the supply pressure port P communicates with the operation port B, and the return oil from the operation port A flows into the left tank port T.

When the spool 3 is thus switched and operated, the working oil flows through the orifice formed between each land and the port. At this time, the momentum of the working oil changes, In order to reduce the fluid force acting on the spool 3 in the axial direction, buckets 4 and 5 for fluid force compensation are provided on the spool 3 at the left and right of the land 11.
Further, buckets 6 and 7 are formed outside the lands 14 and 15.

Each of these buckets 4 to 7 changes the flow direction of the hydraulic oil so that the fluid force acts not only in one direction of the spool 3 but also in the opposite direction, that is, the flow of each part acting on the spool 3. It is designed to offset your physical strength.

With the above construction, the operation will be described next. Now, when the spool 3 is in the neutral position as shown in FIG. 1, no working oil flows into either of the working ports A and B. The state becomes a port block (however, the present invention is not limited to this zero wrap type).

From this state, as shown in FIG. 2, when the spool 3 is displaced to the right, the supply pressure port P communicates with the operation port A, and the operation port B communicates with the right tank port T. Therefore, the working oil flows from the supply pressure port P into the working port A, and the return oil from the working port B flows out into the tank port T.

At this time, the working oil flowing from the supply pressure port P to the working port A is the land 1 as shown in FIG.
1 passes through the bucket 4 on the left side, but at this time, the flow direction is reversed, and a fluid force for driving the spool 3 to the right and a fluid force for driving the spool 3 to the opposite left are generated. , These offset each other.

On the other hand, the working oil flowing from the working port B to the tank port T is reversed in the same direction by the action of the bucket 7 on the right side of the land 15, and the spool 3
The fluid forces that try to drive the shafts in the axial direction cancel each other out.

In this way, both of the hydraulic oil flowing from the supply pressure port P to the operating port A and the hydraulic oil flowing from the operating port B to the tank port T, the fluid force that drives the spool 3 in the axial direction. Is compensated separately, even if the flow rates of both flows are different or the pressure loss is different, the influence of the fluid force for driving the spool 3 in one direction almost disappears. This is the same when the spool 3 is displaced in the direction opposite to that in FIG.
The fluid force is compensated by the bucket 5 and the bucket 6, respectively.

Therefore, the solenoid driving force required to displace the spool 3 is reduced and the behavior of the spool 3 is stabilized.

Next, another embodiment will be described.

In the embodiment shown in FIG. 5, the outer diameters of the two lands 12 and 13 located on the left and right of the land 11 are set smaller than the outer diameters of the other lands.

Lands 12 and 13 are operating ports A or B.
When the hydraulic oil flows from the tank port T to the tank port T, it is located on the upstream side of the tank port T. However, by reducing the outer diameters of the lands 12 and 13, the flow of the hydraulic oil becomes smooth and pressure loss is reduced. Can be made smaller.

In the embodiment shown in FIG. 6, as compared with the embodiment shown in FIG. 5, the grooves between the lands 12 and 14 and the lands 13 and 15 are removed, and the lands 12 and 13 are set to have the same diameter. There is. This makes the spool 3 easier to process.

In the embodiment shown in FIG. 7, a sleeve 2a having a valve hole 2 is arranged inside a valve body 1. By forming the sleeve 2a in a cylindrical shape, balance of radial force and application are realized. And workability are improved.

In the embodiment of FIG. 8, the width of the center land 11 of the spool 3 for opening and closing the supply pressure port P is set wider than the width of the supply pressure port P, and a large number of slits are formed on both sides of the outer periphery of the land 11. 21 is formed. With this configuration, when the spool 3 is displaced and the working oil flows from the supply pressure port P, the working oil flows through each slit 21, and the flow can be easily controlled even at a small flow rate. Operation is stable.

In the embodiment shown in FIG. 9, as compared with the embodiment shown in FIG. 8, the lands 12 and 14 and the lands 13 and 15 are integrated and a slit 22 similar to the above is formed at this portion. Differences in points.

Also in this case, the flow rate can be easily controlled even when the flow rate of the hydraulic oil flowing from the operation port A or B to the tank port T is small, and the same effect as the above can be obtained.

Next, each of the embodiments of FIGS. 10 to 12 is different from the embodiment of FIG. 1 in that the shape of the bucket is changed.

That is, in the embodiment shown in FIG. 10, the linear taper 23 is provided instead of the circular arc at the bottom of the buckets 4 to 7, and the shape can be simplified.

In the embodiment shown in FIG. 11, an inclined arc 24 that is inclined only in one direction is formed at the bottom of the buckets 4 to 7, and the flat portion of the bottom is removed.

Further, in the embodiment of FIG. 12, the land 15
The joining end faces of the tank port T and the tank port T are formed with inclined end faces 25a and 25b which are not perpendicular to the axis of the spool 3 but are inclined at a predetermined angle. The same applies to the land 14 and the tank port T on the opposite side.

As described above, even if the bucket shape is not symmetrical, the fluid force in the axial direction can be canceled out.

Next, the embodiment of FIG. 13 is basically the same as the spool 3 shown in the embodiment of FIG. 1, but the right end of the spool 3 is at the left end of the spool 3. A spring 26 is interposed so as to oppose a solenoid (not shown) arranged in the. Between the spring receiver 26a at the right end of the spring 26 and the end wall 1a of the valve body 1, when the spool 3 is in the neutral position, a predetermined distance S
0 is maintained, and at this time, the land 12 and the supply pressure port P
The gap S1 between the ground and the land 13 and the gap S2 between the land 13 and the tank port T are set to be smaller than S0.

With this configuration, when the solenoid for displacing the spool 3 against the spring 26 fails and the thrust force disappears, the spool 3 is separated by the spring 26 from the spring receiver 26a and the end wall 1a. It is pushed all the way to the right until it comes into close contact. However, in this state, a part of the land 12 has a supply pressure port P and an operation port A.
Is blocked, the land 13 also blocks the operation port B and the right tank port T, and the land 14 blocks the left tank port T and the operation port A.
Both the operating ports A and B are shut off from the supply pressure port P and the tank port T.

Therefore, even in the event of such a failure, the operating ports A and B are surely kept in the shut-off state, the fail-safe function is exerted, and the operating oil is prevented from flowing into and out of the operating ports A and B. The actuator etc. can be reliably stopped at that position.

The embodiment of FIG. 14 differs from that of FIG. 13 in that the shape of the bucket 4 on the left side of the land 11 is changed to an annular groove 4a having a simple rectangular cross section.

In this case, since the gap S1 cannot be made large, the groove width of the annular groove 4a is small, and therefore there is little difference in action and effect even if a bucket is not formed. Therefore, the shape is simplified. The workability is improved.

[0046]

According to the first aspect of the invention, the fluid force in the spool axial direction generated when the hydraulic oil flows from the supply pressure port P into the one operation port A or B opens or closes the supply pressure port P. The hydraulic force of the hydraulic oil that is compensated by the action of the hydraulic force compensating bucket provided adjacent to the land that opens and closes the tank port T at this time flows out from the other hydraulic oil port B or A to the tank port T. The hydraulic fluid flowing in either direction is compensated by the fluid force compensating bucket provided adjacent to the spool, and the spool is not subjected to excessive fluid force. Therefore, the driving force required to displace the spool is increased. Can be made small and the behavior of the spool can be stabilized.

According to the second aspect of the present invention, the hydraulic oil flows through the slits, the flow can be easily controlled even at a small flow rate, and the operating characteristics of the spool can be stabilized.

According to the third aspect of the invention, when the thrust of the solenoid or the like for driving the spool is stopped, the spool moves in one direction by the urging force of the spring, and at this time, the operating ports A and B move to the supply pressure port P. , The tank port T is shut off, and therefore the supply and discharge of the hydraulic oil to and from the operation ports A and B are completely stopped, and the fail-safe function at the time of a failure is exhibited.

[Brief description of drawings]

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

FIG. 2 is a sectional view showing an operating state of the same.

FIG. 3 is a sectional view showing a part of the same.

FIG. 4 is a sectional view showing a part of the same.

FIG. 5 is a sectional view showing a second embodiment.

FIG. 6 is a cross-sectional view showing a third embodiment.

FIG. 7 is a sectional view showing a fourth embodiment.

FIG. 8 is a sectional view showing a fifth embodiment.

FIG. 9 is a cross-sectional view showing a sixth embodiment.

FIG. 10 is a sectional view showing a part of the seventh embodiment.

FIG. 11 is a sectional view showing a part of an eighth embodiment.

FIG. 12 is a sectional view showing a part of the ninth embodiment.

FIG. 13 is a sectional view showing a tenth embodiment.

FIG. 14 is a cross-sectional view showing an eleventh embodiment.

FIG. 15 is a sectional view showing a conventional example.

[Explanation of symbols]

 1 Valve Body 2 Valve Hole 3 Spool 4, 5, 6, 7 Fluid Force Compensation Bucket 11, 12, 13, 14, 15, 16, 17 Land 21, 22 Slit

Claims (3)

[Claims] 1. A spool which is slidably accommodated in a valve body, a supply pressure port P formed in a valve hole around the spool, operation ports A and B, left and right tank ports T, and these respective ports are selected. A plurality of lands formed on the spool so that the supply pressure port P can be either the operation port A or the operation port B according to the displacement of the spool.
At the same time, in the directional flow control valve in which either the other operation port B or A is switched and connected to the tank port T, adjacent to the left and right of the land for opening and closing the supply pressure port P, the fluid force in the spool axial direction is offset. A directional flow control valve, characterized in that a bucket for fluid force compensation and a bucket for fluid force compensation are respectively formed adjacent to lands that also open and close the tank port T. 2. The directional flow control valve according to claim 1, wherein a slit extending in the axial direction for guiding the flow of hydraulic oil is formed on the outer periphery of the land. 3. A spring according to claim 1, further comprising a spring for urging the spool in one direction, and a land provided so as to close both the operation ports A and B when the spool moves to the limit by the spring. Directional flow control valve described.