JPS59140976A - Damping device of pilot switch valve - Google Patents

Abstract

PURPOSE:To prevent hunting and a sudden increase in pressure in a circuit by bending a spring positioned forward in the moving direction and bending a spring positioned in the rear when a spool is moved from the neutral position. CONSTITUTION:In a switch valve where a valve body (a) comprising a body 12 and covers 13, 14 fixed to both ends of the body incorporates a spool 15 in such a manner as to freely slide, circular gooves 35, 36 are formed on both ends of the spool 15, and each pair of spring sheets 43, 44; 45, 46 are slidably fitted in the respective grooves 35, 36. Compression springs 49, 50 are interposed between the sheets 43, 44 and between the sheets 45, 46, respectively, thereby to retain the spool 15 at the neutral position when the above pilot pressure chambers 51 52 are in the state of tank pressure. When the spool 15 is moved from the neutral position to the right, for example, the spool is moved against the spring 50 for the travel L1, and moved against the springs 49, 50 for more than the travel L1.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a damping device for a switching valve that operates a spool using pilot pressure.

(Conventional Device) In the conventionally known device shown in FIG. Adjacent in the axial direction, the small diameter hole 3 is located on the outside and the large diameter hole 4 is located on the inside, and a stepped portion 5 is formed at the boundary between these two holes 3.4.

One end of the spool 6 faces inside the small diameter hole 3, and together with this spool 6, a pilot pressure chamber 7 is formed. is formed. Further, the large diameter hole 4 communicates with a pilot pressure introduction hole 8 formed in the main body 1.

At one end of the spool 6, a small hole 0 is formed which is always open to the large diameter hole 4 side. Pressure chamber 7
We have a relationship where we communicate with each other.

Further, a single oil hole 11 is formed outside the small hole 10, and the oil hole 11 can be moved from the illustrated position to the position corresponding to the large diameter hole 4 depending on the movement position of the spool 6. I'm trying to make it moveable.

When the pilot pressure flows in from the pilot pressure introduction hole 8, the pilot pressure changes from the large diameter hole 4 to the small hole lO.
→Flows into the pilot pressure chamber 7 via the check valve 9. The pilot pressure that has flowed into the chamber 7 in this manner acts on the spool 6 to move the spool 6 rightward in the drawing, so that the oil passage hole 11 corresponds to the large diameter hole 4.

At the initial stage when the spool 6 moves leftward from the above state and returns to the original position shown in the figure, the oil passage hole 11 is open to the large diameter hole 4 side, so the oil in the pilot pressure chamber 7 is but,
The oil flows directly into the large diameter hole 4 through the oil passage hole 11 . Then, when the spool 6 further moves to the left and the oil passage hole 11 is positioned within the small diameter hole 3, the oil in the pilot pressure chamber 7 flows out from the oil passage hole 11 to the large diameter hole 4 via the clearance. I will do it.

Therefore, the damping effect at a minute required position changes depending on the stroke of the spool, and when the spool switching pressure due to the pilot pressure is low, the spool return speed due to the spring load becomes slow, resulting in poor responsiveness.

(Objective of the Invention) The object of the invention is to provide a damping device for a pilot switching valve that further stabilizes the damping effect, prevents hunting in a small required position range, and improves responsiveness.

(Embodiment of the present invention) The valve body a of this embodiment shown in Figs. 1 to 3 consists of a main body 12 and covers 13 and 14 firmly attached to both ends thereof. , spool 15
The interior is slidable.

This main body 12 has the first to fourth ports 16 to 18.
However, the first boat 16 and the second boat 17 are connected via a switching valve (not shown).

The third port 1B and the fourth port 19, which are connected to either the pump or the tank, are always in communication with the actuator 20.

Further, the cover 13.14 has a small diameter hole 21.22 and a large diameter hole 23.24, which are adjacent to each other in the axial direction, with the small diameter hole 21.22 on the outside. The large-diameter holes 23.24 are located inside, and a stopper 25.26 consisting of a stepped portion is formed at the boundary between the two holes 21.22 and 23.24. Furthermore, the main body 12
Also, a stopper 27.2 consisting of a stepped portion is formed, and these stoppers 25, 27, 26, and 28 are opposed to each other. A relay chamber 53.54 is formed between the opposing portions of both stoppers.
54 communicates with Il, 2 ports 1B, and 17 via supply/discharge passages 55 and 56.

And, the spool 15 has a pair of annular four parts 29.
．． 30, and the annular recesses 29 and 30 communicate the first and third ports or the second and fourth boats through either one of the annular recesses when the first pool 15 moves from side to side. let

Furthermore, this spool 15 has a 1st and 2nd port 16.
An oil passage hole 31.32 is formed that constantly communicates with the 1.2 port 16.
．． Check valves 33, 34 are provided that allow flow only from port 17 to port 3.4, port 18, 19.

Both ends of the spool 15 thus constructed have an annular groove 35.
3Et, and hooking portions 37 at both ends of this groove 35,36.
.about.40, and the outside of this hooking portion 37.40 is a two-rung portion 58.58. This flange portion 58
．． 59 protrudes into the small diameter hole 21.22, and the small diameter hole and the flange portion combine to form the pilot pressure chamber 5I,
52.

Then, set the outer diameter of this flange portion 58.58 to the small diameter hole 2.
1.22, and a gap 41.42 is formed between them.

A pair of spring seats 43, 44, 45 and 46 are slidably fitted into the annular groove 35.36, and a compression spring 48.5 is inserted between the pair of spring seats.
0 is interposed. And the pilot pressure chamber 51
．． When 52 is the tank pressure, the spool 15 is held in the neutral position shown in FIG. 3 by the action of the compression spring. In other words, the outer spring seat 43.46 presses against the stopper 25, 26, and the inner spring seat 44.45 presses against the stopper 27.28 and the stopper 38.39.
and the spool 15 is held in the neutral position shown in FIG.

And the above-mentioned stoppers 25 and 27.2 which are in contact with each other
Since the distance between the pair of latching portions 37 and 38 and 39 and 40 facing each other is made larger than the distance between 8 and 28,
When the spool 15 is held in the neutral position as described above, the flange portion 58.
59 and the spring seats 43, 46 are separated.

The inner periphery of the spring seat 43, 46 as described above,
In other words, the inner diameter of the spool through hole formed in the center is
It is made slightly larger than the outer diameter of the annular groove 35, 36 so that a gap of 47.4 days is formed between the two.

Note that when the spool 15 is held in the neutral position as described above, the distance L1 between the stopper 25.26 and the hook portion 37.40 is equal to
2 and the land wrap L2 of the spool 15, and the annular recess 2
9.30 is equal to the sum of the 3.4th boat 18.19 and the slightly required minute position range L3.

Now, for example, if hydraulic oil is supplied to the first port 16,
The hydraulic fluid pushes open the check valve 33 and releases the actuator 2.
At the same time, it flows into the pilot pressure chamber 51 via the supply/discharge passage 55 → relay chamber 53 → gap 47 → gap 41. The pilot pressure that has flowed into the pilot pressure chamber 51 acts on the end surface of the spool 15 and moves the spool 15 to the right in the drawing, but during this movement process, the amount of movement of the spool 15 is less than or equal to the above-mentioned interval Ll. At this time, it moves against the spring 50. Then, when moving beyond the above distance, the hooking part 37 will come into contact with the spring seat 43, so after that contact,
It is moved against springs 48 and 50 to maintain the position shown in FIG.

Therefore, the return oil from the actuator 20 returns to the tank through the fourth bow) 19 → the annular recess 30 → the second bow) 17.

When the spool 15 returns from the state shown in FIG. 2 to the neutral position by communicating the pilot pressure chamber 51 with the tank, the spring seat 43 separates from the stopper 25 in the initial stage of the return. Therefore, the damping effect is exerted only by the gap 41.

After the spring seat 43 contacts the stopper 25, the damping effect is exerted by the gap 47.

Therefore, if the opening area of the gap 47 is made smaller than that of the gap 41, the spool 15 will move smoothly up to the predetermined stroke L2, and will return slowly within the required minute position range L3. Moreover, although the spring force of both springs 49 and 50 acts on the return at the initial stage, the return force after the spring seat 43 contacts the stopper 25 is exerted only by one of the springs 50. , the damping effect becomes even greater in the small required position range.

(Configuration of the present invention) The configuration of the present invention includes a spool internally installed in the valve body,
In the pilot switching valve in which both ends of the spool face the pilot pressure chamber, a pair of sprig seats are slidably attached to both ends of the spool, and a spring is interposed between these spring seats, With this spring, the spool normally maintains a neutral position, and when the spool moves from the neutral position, the spring located at the front in the direction of movement is deflected, and then the spring at the rear in the direction of movement is deflected. It is characterized by the following points.

(Effects of the present invention) As described above, when the spool moves from the neutral position, the spring at the front in the direction of movement is deflected, and then the spring at the rear in the direction of movement is deflected, so that the spool cannot be moved until it reaches a predetermined position. It is possible to move quickly and then move slowly. Therefore, the spool should be moved quickly up to the required minute position range to improve responsiveness, and the spool should be moved slowly within the required minute position range where hunting is likely to occur to prevent hunting and sudden pressure increases in the circuit. It can be prevented.

[Brief explanation of the drawing]

Drawings WS1 to WS3 show an embodiment of the present invention, in which the IF diagram is a cross-sectional view with the spool held in a neutral position, FIG. 2 is a cross-sectional view with the spool moved to the right, and FIG. 3
The figure is an enlarged view of the main part, and FIG. 4 is a sectional view of the conventional device. aq's valve body, 15...spool, 41.
42---Gap, 51.52---Pilot pressure chamber, 5
3.54... Relay room, 55.56... Supply/discharge passage. Representative Patent Attorney Nobuyuki Shima

Claims (1)

[Claims] In a pilot switching valve in which a spool is housed in the valve body and both ends of the spool face the pilot pressure chamber, a pair of sprig seats are slidably attached to both ends of the spool, and there is a gap between these spring seats. A spring is interposed between the
A pilot switching valve configured such that the spool normally maintains a neutral position, and when the spool moves from the neutral position, a spring located at the front in the direction of movement is deflected, and then a spring at the rear in the direction of movement is deflected. damping device.