JPH0440056Y2 - - Google Patents

Description

[Detailed explanation of the idea] (Industrial application field) The present invention relates to an electromagnetic proportional pressure control valve.

(Prior Art) Conventionally, as an electromagnetic proportional pressure control valve, one described in, for example, Japanese Unexamined Patent Publication No. 182811/1983 is known.

In this conventional electromagnetic proportional pressure control valve, a valve spool that controls output hydraulic pressure is slidably installed in the valve hole, and a reaction piston is slidably inserted into the feedback hydraulic pressure chambers at both ends of this valve spool. A solenoid for pressing the valve spool is provided on the outside of both ends of the valve spool, and the plunger, reaction piston, and valve spool of the solenoid are coaxially provided, and the pressing force of the solenoid is The structure was such that the reaction force was transmitted via a piston.

Therefore, when one solenoid is driven, the valve spool is pushed by the plunger and slides toward the other solenoid, increasing the output hydraulic pressure. Due to this increase in output hydraulic pressure, the reaction piston located on the sliding direction side of the valve spool receives feedback hydraulic pressure, and slides toward the other solenoid relative to the valve spool.
When the sliding of this reaction piston is restricted, the reaction force of the feedback fluid pressure applied to the reaction piston acts on the valve spool, pushing the valve spool back, and this reaction force causes the feedback fluid to increase. The pressure and the pressing force of one solenoid are balanced, and the output hydraulic pressure of one side is controlled to be a hydraulic pressure proportional to the pressing force of the solenoid, that is, the electromagnetic force. Incidentally, when the valve spool is pushed back by the feedback hydraulic pressure in this manner, the reaction piston remains at a position where sliding is restricted and is displaced so as to protrude relative to the valve spool.

Additionally, when the other solenoid is driven, the reaction piston, which had been displaced relative to the valve spool and protruding, is pushed into the valve spool, and the pressing force of the solenoid is transferred through this reaction piston. can be transmitted to the valve spool. The valve spool is then slid in the opposite direction as described above and the other output hydraulic pressure is controlled in the same manner as described above.

In this way, in this conventional control valve, the feedback fluid pressure is obtained from the reaction force of the reaction piston, so
Compared to a system in which the feedback hydraulic pressure is received at the end face of the valve spool, the pressure receiving area can be made smaller, thereby making it possible to increase the output hydraulic pressure.

(Problem to be solved by the invention) However, such conventional electromagnetic proportional pressure control valves have a structure in which feedback hydraulic pressure is received by reaction pistons inserted into both ends of the valve spool. As it was getting older, there were problems listed below.

Due to the suction force of the solenoid, it is not possible to have a large feedback pressure receiving area.In other words, if a compact solenoid is used, the reaction piston and feedback pressure chamber for receiving the opposing feedback pressure must be made smaller. This makes machining such a small-diameter reaction force piston and machining a small-diameter hole difficult, which adversely affects static characteristics (hysteresis, threshold, etc.).

Because it is difficult to make the reaction piston and the feedback hydraulic pressure chamber small within the range in which the reaction piston can slide smoothly, it is difficult to reduce the receiving pressure of the feedback hydraulic pressure. , it is difficult to increase the output hydraulic pressure while keeping the solenoid compact.

When the driving solenoid is switched from one side to the other, the valve spool cannot slide until the reaction piston is pushed into the feedback hydraulic pressure chamber by the solenoid, which causes a response delay and changes the dynamic characteristics. have a negative impact.

(Means for solving the problems) The present invention solves the above-mentioned problems, has good responsiveness, and can easily reduce the pressure receiving area of the feedback fluid pressure, which does not adversely affect static characteristics. It is an object of the present invention to provide an electromagnetic proportional pressure control valve which does not cause a large amount of pressure and can easily increase the output hydraulic pressure while using a small solenoid.

To achieve this objective, the present invention includes a valve spool that is slidably provided in a valve hole of a valve body and controls the hydraulic pressure of two output circuits, a first output hydraulic pressure and a second output hydraulic pressure; a first solenoid that presses the valve spool from one end side in a first output hydraulic pressure increasing direction; a second solenoid that presses the valve spool from the other end side in a second output hydraulic pressure increasing direction; and the valve spool. A second step portion and a first step portion formed by forming the one end portion and the other end portion thereof to have a diameter smaller than the land corresponding to the valve hole, respectively, and the valve spool of the first step portion and the valve body. A first feedback chamber is formed between the valve spool and the valve body of the second stepped portion, and a second feedback chamber is formed between the valve body and the second output hydraulic pressure. It was used as a means of

(Operation) The electromagnetic proportional pressure control valve of the present invention operates as described below.

When the first solenoid is energized, the first solenoid presses one end of the valve spool with the generated suction force,
The valve spool is slid in the direction of increasing the first output hydraulic pressure, and the first output hydraulic pressure increases.

Corresponding to the increase in the first output hydraulic pressure, the hydraulic pressure in the first feedback chamber is also increased.

This first feedback chamber is formed at the first step at the other end of the valve spool, and the pressure receiving area on the center side of the valve spool is widened by the difference in diameter. The valve spool receives this feedback hydraulic pressure toward the center and is pushed back in the direction in which the first solenoid is pressed.

The valve spool is arranged at a position where the pressing force of the first solenoid and the receiving force of the feedback hydraulic pressure are balanced, and the first output hydraulic pressure is the same as that of the first solenoid.
The hydraulic pressure is controlled in proportion to the suction force of the solenoid.

Next, when the second solenoid is driven, the second solenoid immediately presses the valve spool in the direction of increasing the second output hydraulic pressure, the valve spool is slid in the opposite direction, and the second output hydraulic pressure is increased. At the same time, the feedback fluid pressure is received at the second step,
The second output hydraulic pressure is controlled to be proportional to the suction force of the second solenoid.

In this way, when switching the drive of both solenoids from the first solenoid to the second solenoid or vice versa, since there is no reaction piston interposed between both solenoids and the valve spool, the valve spool It slides immediately, and there is no response delay due to the intervention of a reaction piston.

Further, in the present invention, as described above, the valve spool is formed with first and second stepped portions having different diameters, and the feedback hydraulic pressure is received by the difference in pressure receiving area due to the stepped portions.

Therefore, the pressure receiving area of this feedback liquid pressure can be determined simply by how small the diameter of the lands at both ends of the valve spool is compared to the land on the center side corresponding to the valve hole, and is determined by the setting and processing. It is easy to do this, and it is also easy to set the pressure receiving area small.

(Example) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

First, the configuration of the embodiment will be explained.

FIG. 1 is a sectional view showing an electromagnetic proportional pressure control valve according to an embodiment of the present invention, and this electromagnetic proportional pressure control valve includes a pump pressure circuit P, a first output circuit S1, and a second output circuit S2. and is connected to the drain circuit T. Note that both output circuits S1 and S2 are connected to a hydraulic actuator (not shown) so as to be driven by these output hydraulic pressures.

In the figure, reference numeral 10 indicates a valve body, in which a valve hole 11 is bored, and this valve hole 11 is connected to a first output hydraulic port 111 that communicates with the first output circuit S1 and a first output hydraulic port 111 that communicates with the second output circuit S2. A second output hydraulic pressure port 112 is formed, and the pump pressure circuit P is communicated with the position between the two output hydraulic pressure ports 111 and 112, and the outer position of both the output hydraulic pressure ports 111 and 112 is connected to the second output hydraulic pressure port 112. It is connected to the drain circuit T.

Furthermore, a first back chamber 13 and a second back chamber 14 having a larger diameter than the valve hole 11 are formed at both ends of the valve hole 11 . That is, the valve body 10
A first solenoid 30 and a second solenoid 40 are provided at both ends of the solenoid, and both back chambers are closed by casings 32 and 42 of both solenoids 30 and 40, respectively.
Note that 101 and 101 are seal rings.

A valve spool 20 is inserted into the valve hole 11 so as to be slidable in the axial direction. This valve spool 20 has a first land 21, a second land 22, a third land 23, a fourth land 24, a fifth land 25, and a sixth land 26.
Both lands 21 and 22 are provided in an underlapping state so as to form a first aperture a, a second aperture b, a third aperture c, and a fourth aperture d with respect to the valve bodies of both output hydraulic ports 111 and 112, respectively. , the first output liquid pressure P1 and the second output liquid pressure of both output circuits S1 and S2 are reduced by changing the respective throttling amounts and throttling the drain amount of liquid supplied from the pump pressure circuit P to both ports 111 and 112. The pressure P2 is controlled.

The fifth land 25 and the sixth land 26 at both ends are formed to have a smaller diameter than the other lands 21 to 24, and have a first step portion 27 and a second step portion between them and the third and fourth lands 23 and 24. A portion 28 is formed. That is, as shown in FIG. 2, which is an enlarged sectional view of section A, the third land 23
and the fifth land 25 is provided with a diameter difference r,
The vertical wall surface 231 of the third land 23 is the fifth land 25
It is wider than the vertical wall surface 251 corresponding to the diameter difference r. Therefore, when hydraulic pressure is applied to the first stepped portion 27, the third land 23
5 receives more hydraulic pressure toward the center of the valve spool 20 (leftward in the figure).
Note that a similar diameter difference r is provided in the second step portion 28 between the fourth land 24 and the sixth land 26.

Further, the fifth and sixth lands 25 and 26 are
As shown in FIG. 1, it is slidably supported by guide bushes 51 and 52 that are separate members from the valve body 10.

The guide bushes 51 and 52 are provided with screw threads 1 formed in both back chambers 13 and 14 of the valve body 10.
31, 141 by screwing.
That is, the lands 25 at both ends of the valve spool 20,
26 has a small diameter, but guide bushes 51 and 52
By assembling the valve spool 20 later.
can be inserted into the valve hole 11.

Further, outer recesses 511 and 521 and center side recesses 512 and 522 are formed in the centers of the guide bushes 51 and 52, respectively.
11, 521, retainers 61, 62 are set in a state where they are urged by springs 71, 72, respectively, and when the valve spool 20 is neutral, the end surfaces of the retainers 61, 62 and the end surface of the valve spool 20 are on the same plane, and both springs 71 , 72 are not biased.

Further, the central recess 5 of the guide bush 51
A first feedback chamber 81 is formed surrounded by the valve body 12, the valve body 10, and the first step 27, and a second feedback chamber 82 is also formed at the second step 28. A first communication hole 201 formed in the valve spool 20 communicates the first output hydraulic pressure port 111 with the first feedback chamber 81, and a second communication hole 202 similarly formed in the valve spool 20 communicates with the first output hydraulic pressure port 111 and the first feedback chamber 81. Output hydraulic port 112 and second feedback chamber 82
are being communicated.

The first solenoid 30 and the second solenoid 4
0 presses the valve spool 20 with a suction force according to the input current, and both solenoids 30 and 40
The tips of the plungers 31 and 41 are in direct contact with the end face of the valve spool 29, respectively.

Next, the operation of the first embodiment will be explained.

(a) Neutral state Each throttle a, b, c, d formed between the valve spool 20 and the valve body 10 is sufficiently opened, and the supply liquid pressure from the pump pressure circuit P is circulated to the drain circuit T. , no hydraulic pressure is output to both output circuits S1 and S2.

(b) When the first solenoid is activated The neutral state shown in Figure 1 (both solenoids 30 and 4
When the first solenoid 30 is driven from the OFF state), the plunger 31 is activated according to the generated suction force.
The tip of the valve spool 20 presses the valve spool 20 and displaces it to the right in FIG. At this time, the first and second lands 21 and 22 widen the second and fourth throttles b and d, and narrow the first and third throttles a and c, increasing the first output hydraulic pressure P1. , Meanwhile, the second output hydraulic pressure P2 decreases.

When the first output hydraulic pressure P1 increases in this way, the increased hydraulic pressure is applied to the first output hydraulic pressure P1 communicated through the first communication hole 201.
The information is transmitted to the feedback chamber 81.

In the valve spool 20, this feedback hydraulic pressure Pf is determined based on the diameter difference r at the first step portion 27.
is received in the direction of pushing back the valve spool 20 (to the left in the figure), the valve spool 20 is pushed back to the left in the figure, and the pushing force of the first solenoid 30, the feedback hydraulic pressure Pf, and the biasing force of the spring 71 are combined. is displaced to a balanced position. Thereby, the first output hydraulic pressure P1 is controlled to a hydraulic pressure proportional to the suction force of the first solenoid 30.

In this manner, the receiving pressure of the feedback hydraulic pressure Pf of the valve spool 20 can be easily reduced by reducing the diameter difference r between the stepped portions 27 and 28. Therefore, even if both output hydraulic pressures P1 and P2 are increased, a large receiving pressure can be prevented from acting on the valve spool 20, that is, the solenoids 30 and 40
both output hydraulic pressures P1 and P2 while using a small one.
can be easily increased.

(c) When the first solenoid suction force decreases When the input current of the first solenoid 30 decreases from the state (b), the suction force of the first solenoid 30 weakens, and the receiving pressure of the feedback fluid pressure Pf and the spring 71 decrease. Since the biasing force becomes larger, the valve spool 20 is displaced from the position in (b) to the left in the figure. Then, due to this displacement, the first and third throttles a and c are opened, and thereby the first output hydraulic pressure P
1 is reduced, and the biasing force of the spring 71 is reduced due to the change in the spring length due to this displacement, and this reduced first output hydraulic pressure P1 and the spring 71
The displacement of the valve spool 20 is stopped at a position where the urging force of the first solenoid 30 and the weakened suction force of the first solenoid 30 are balanced.

(d) When the second solenoid is driven When the first solenoid 30 is stopped from the state of (b) or (c) and the second solenoid 40 is driven, the feedback fluid pressure in the first feedback chamber 81 and the spring 71 are Due to the urging force and the suction force of the second solenoid 40, the valve spool 20 is displaced to the left in the figure, and, contrary to the case of the first solenoid 30 described above, the first and third throttles a and c are opened and the second solenoid 40 is opened. 2. The fourth apertures b and d are closed.

As a result, the second output hydraulic pressure P2 is increased, and the hydraulic pressure in the second feedback chamber 82 is also increased, and similarly to the case (b) above, the feedback hydraulic pressure is increased at the second step portion 28 this time. This received pressure acts on the valve spool 20 in the right direction in the figure against the pushing force of the second solenoid 40, and the valve spool 20 is forced to act against the pushing force of the second solenoid 20 and the receiving force of the second stepped portion 28. It is stopped at a position where the pressure and the urging force of the spring 72 are balanced, and the second output hydraulic pressure P2
is controlled to a hydraulic pressure proportional to the pressing force of the second solenoid 40.

As explained above, in the electromagnetic proportional pressure control valve of this embodiment, when the driving of the first solenoid 30 and the second solenoid 40 is switched, a reaction piston is generated between the two solenoids 30, 40 and the valve spool 20. Since there is no intervention, valve spool 2
0 slides immediately, and there is no response delay due to the intervention of the reaction piston.

Further, since the portion that receives the feedback liquid pressure is the diameter difference between the first and second step portions 27 and 28, it is extremely easy to process this pressure receiving area to a small size, and the accuracy is also high.

Therefore, by reducing this pressure receiving area, the output hydraulic pressure can be increased while using a small solenoid without adversely affecting static characteristics such as hysteresis and threshold.

(Effects of the invention) As explained above, in the electromagnetic proportional pressure control valve of the invention, since there is no reaction piston interposed between both solenoids and the valve spool, the pressing force of the solenoid is reduced to that of the solenoid. It can transmit information to the valve spool at the same time as driving, resulting in good responsiveness.

In addition, since the part that receives the feedback fluid pressure of the valve spool is made of the first and second stepped parts formed by the difference in land diameter, it is very easy to process the pressure receiving area to a small size, and it is possible to reduce hysteresis, threshold, etc. The advantage is that the static characteristics are not adversely affected, and the output hydraulic pressure can be easily increased while using a small solenoid.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an electromagnetic proportional pressure control valve according to an embodiment of the present invention, and FIG. 2 is an enlarged sectional view of section A of the embodiment. 10... Valve body, 11... Valve hole, 2
0...Valve spool, 21...1st land, 2
2...2nd land, 23...3rd land, 24...
...4th land, 25...5th land (small diameter), 2
6... 6th land (small diameter), 27... 1st step part,
28... Second step portion, 30... First solenoid,
40...Second solenoid, 81...First feedback chamber, 82...Second feedback chamber, P1
...First output hydraulic pressure, P2...Second output hydraulic pressure.

Claims (1)

[Claims for Utility Model Registration] A valve spool that is slidably provided in a valve hole of a valve body and controls the hydraulic pressure of two output circuits, a first output hydraulic pressure and a second output hydraulic pressure; a first solenoid that presses the valve spool in the direction of increasing the first output hydraulic pressure from one end; a second solenoid that presses the valve spool in the direction of increasing the second output hydraulic pressure from the other end; and the one end of the valve spool. a second stepped portion and a first stepped portion formed by forming the land and the other end portion respectively to have a smaller diameter than the land corresponding to the valve hole; and a second stepped portion and a first stepped portion formed between the valve spool and the valve body of the first stepped portion; A first feedback chamber to which the first output hydraulic pressure is guided; and a second feedback chamber formed between the valve spool of the second stepped portion and the valve body and to which the second output hydraulic pressure is guided. Features an electromagnetic proportional pressure control valve.