JPS6128528Y2 - - Google Patents

Description

[Detailed Description of the Invention] This invention relates to a counterbalance valve that prevents spool hunting.

As this type of counterbalance valve, the counterbalance valve shown in FIGS. 1 and 2 is conventionally known.

This conventional counterbalance valve C is used by being connected to a hydraulic cylinder 1, for example, as shown in FIG. 1, and has the following configuration.

That is, the spool 3, which is slidably installed inside the valve body 2, has a convex portion 4 formed at one end (left end in the drawing) facing the pilot pressure chamber 5, and the other end facing the damper chamber 6. A spring 7 is interposed in this damper chamber 6, and normally, the action of the spring 7 causes the tapered portion 8 of the spool 3 to
is in contact with the stepped portion 9 of the valve body 2.

In the state where the tapered portion 8 is in contact with the stepped portion 9 as described above, another damper chamber 10 is formed on the opposite side from the damper chamber 6, and the port 11
The structure is such that communication between the annular groove 12 and the annular groove 12 and the communication hole 13 is cut off.

However, when the changeover valve 14 in FIG. It flows into the side chamber 18, and its cylinder 1
workpiece W is raised. Further, the oil in the rod side chamber 19 of the hydraulic cylinder 1 is returned to the tank 22 via ports 20 and 21.

On the other hand, when the switching valve 14 is switched to the left position, the oil discharged from the pump 15 flows into the rod side chamber 19 through ports 21 and 20, and also flows into the pilot pressure chamber 5. Therefore, the spool 3 moves against the spring 7, but at this time, the oil in the damper chamber 6 flows into the orifice 2.
3 flows out, a damping effect is exerted, and the spool 3 moves slowly.

When the spool 3 moves as described above, the tapered portion 8 and the step portion 9 are fused, and the port 11 and the annular groove 12 communicate with each other, and the communication hole 13 and the annular groove 12 also communicate with each other. Therefore, the oil in the piston side chamber 18 is returned to the tank 22 via the port 17, the communication hole 13, and the port 11.

At the moment when the spool 3 moves as described above and the tapered part 8 and the stepped part 9 melt, the pressure in the piston side chamber 18 drops rapidly. When the pressure in the piston side chamber 18 decreases, most of the oil discharged from the pump 15 flows into the rod side chamber 19.
It does not flow into the pilot pressure chamber 5. Therefore, the pressure within the pilot pressure chamber 5 decreases, and the spool 3 attempts to return to its original position. The orifice 23' causes the spool 3 to return slowly.
In other words, when the spool 3 attempts to return as described above, the oil in the damper chamber 10 flows into the orifice 2.
3', a so-called damping effect is exhibited.

As mentioned above, the damping effect is exhibited to prevent the occurrence of spool hunting, but the biggest drawback of this conventional valve is that in order to make the damper chamber 10 large, the spool 3 itself has to be made large. The reason for this is as follows.

That is, the damping effect is determined by the ratio of the pressure receiving area of the spool 3 in the damper chamber 10 to the opening area of the orifice 23'. In other words, the spool 3 is
When the pressure receiving area is sufficiently large, the damping effect becomes significantly large.

Therefore, in order to increase the damping effect, the pressure receiving area, that is, the spool 3 itself must have a large diameter. Therefore, with this conventional valve, the size of the valve had to be increased.

The cause of this is that the spool is directly connected to the damper chamber 10.
This is because the spool 3 has a pressure receiving surface facing inside the damper chamber 10.

The purpose of this invention is to provide a counterbalance valve that can exhibit a sufficient damping effect without increasing the diameter of the spool itself.

In order to achieve the above object, the spool and damper chamber are separated.

The embodiment shown in FIGS. 3 and 4 will be described below.

Valve body 24 of this counterbalance valve A
has plugs 25 and 26 on the same line at both ends.
At the same time as fitting the valve boats 27 and 28
and actuator ports 29 and 30 are formed.

The valve ports 27 and 28 are connected to the switching valve 31 shown in FIG.
9 and 30 are connected to a piston side chamber 33 and a rod side chamber 34 of the cylinder 32.

The valve port 27 and the actuator port 29 are connected via a facing chamber 35, a communication hole 36, and a check valve 37. The relationship is set to allow only

Also, valve port 28 and actuator port 3
0 is configured to constantly communicate with the plug 25 via a pilot chamber 38 formed in the plug 25. Furthermore, a damper spool 39 is slidably installed inside the plug 25, and damper chambers 40, 41 are provided on both sides of the damper spool 39.

Convex portions 42 and 43 are formed on both sides of the damper spool 39, with one convex portion 42 facing into the pilot chamber 38 and the other convex portion 43 facing into the facing chamber 35. There is.

A first orifice 44 is provided in one of the protrusions 42 facing into the pilot chamber 38 as described above.
Through this first orifice 44, the pilot chamber 3
8 is communicated with the damper chamber 41 on the right side of the drawing. Further, the damper chamber 40 on the left side of the drawing is connected to the actuator port 30 through the second orifice 45.
is connected to.

On the other hand, a spool 46 that is slidably installed in the valve body 24 with substantially the same axis as the damper spool 39 is connected to a spring 46 in the damper chamber 47.
Normally, it is held in the position shown in FIG. In this state shown in FIG. 4, the spool 4
6 has its protruding end portion 49 facing into the facing chamber 35, and faces the protruding portion 43 with a slight gap therebetween. In this state, communication between the facing chamber 35 and the annular groove 50, and between the annular groove 50 and the actuator port 29 are blocked.

Note that the damper chamber 47 has a third orifice 51.
It communicates with the facing room 35 via.

When the switching valve 31 shown in FIG. 3 is switched to the left side position in the figure, the oil discharged from the pump 52 flows into the valve port 27, passes through the facing chamber 35 and the communication hole 36, and pushes the check valve 37 open. , flows out from the actuator port 29. The oil flowing out from the actuator port 29 further flows into the piston side chamber 33 of the cylinder 32 and raises the workpiece W. At this time, the oil in the rod side chamber 34 is returned to the tank 53 as it is.

Next, when the switching valve 31 is switched to the right position in FIG. Inflow.

At this time, the pressure within the pilot chamber 38 acts on the end surface of the convex portion 42, causing the damper spool 39 to move rightward in the drawing. When the spool 39 moves in this manner, the oil in the damper chamber 41 passes through the first orifice 44, so the movement becomes slow. In other words, a damping effect is exhibited.

When the damper spool 39 moves further, the protrusion 43 comes into contact with the protrusion 49 of the spool 46, and the spool 46 is moved against the spring 48. When the spool 46 moves, the actuator port 27 connects the annular groove 50 and the spool 46.
Valve port 29 via annular groove 54 formed in
Since the oil in the piston side chamber 33 is returned to the tank 53, the workpiece W is lowered.

The moment the piston side chamber 33 communicates with the tank 53, the pressure in the chamber 33 drops rapidly, and when the pressure in the pilot chamber 38 drops accordingly, the spool 46 returns to its original position by the action of the spring 48. trying to return to. The return force of the spool 46 is naturally transmitted to the damper spool 39, and the damper spool 39 also moves, but at this time, the oil in the damper chamber 40 is transferred to the second orifice 45.
, the recovery will be extremely slow. In other words, the damping effect is fully demonstrated,
To prevent the so-called hunting phenomenon from occurring.

In this invention, the damper spool 39 is separated from the spool 46, and the outer diameter of the damper spool 39 is made sufficiently large, so that the pressure receiving area and the first and second orifices 44, 4
5 becomes large, the damping effect is significantly improved, and a desired damper can be obtained regardless of the size of the spool 46.

Note that the third orifice 51 is connected to the spool 46.
When it moves against the spring 48, it exhibits a damping effect. However, at this time, the damping effect can also be obtained by the first orifice 44 of the damper spool 39, so the third orifice 51
is not absolutely necessary. However, if the third orifice 51 is provided as in this embodiment, the first
Together with the orifice 44, its damping effect becomes even greater.

As is clear from the above explanation, according to the counterbalance valve of this invention, the outer diameter of the damper spool can be made large regardless of the size of the spool, so the pressure receiving area of the damper spool and the opening area of the first and second orifices can be increased. It is possible to increase the relative difference between the damping effect and the damping effect.

Furthermore, even if the outer diameter of the damper spool is increased, there is no need to increase the size of the spool, and therefore, the counterbalance valve itself can be downsized while maximizing the damping effect.

[Brief explanation of the drawing]

Figures 1 and 2 show a conventional counterbalance valve, Figure 1 is a circuit diagram of it connected to a cylinder of a crane, etc., Figure 2 is a cross-sectional view, and Figures 3 and 4 are diagrams of this invention. FIG. 3 is a circuit diagram similar to FIG. 1, and FIG. 4 is a sectional view. 39...damper spool, 40, 41...damper chamber, 44...first orifice, 45...second orifice, 46...spool.

Claims (1)

[Scope of utility model registration request] It comprises a spool that opens and closes a predetermined flow path, a damper spool separate from this spool, and damper chambers provided on both sides of the damper spool, and the spool and the damper spool are configured to follow and move, A counterbalance valve in which each of the damper chambers is communicated with a first orifice and a second orifice for exerting a damping effect, and the outer diameter of the damper spool is larger than the outer diameter of the spool.