JPH055343Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to a return speed control mechanism for a pilot spool valve that alleviates the shock when the spool returns to a neutral position.

(Prior Art) The conventional spool valve shown in FIG. 5 has a spool 2 slidably installed inside its main body 1, and
Both ends of this spool 2 face a pilot chamber 4 consisting of a cap 3 attached to the main body 1.

As mentioned above, the plug 5 is fitted to the end of the spool 2 facing the pilot chamber 4, and the protruding part of the plug 5 protruding from the spool 2 is inserted into the center hole 7 of the spring receiver 6, and the plug 5 is inserted into the center hole 7 of the spring receiver 6. plug 5
and the spring receiver 6 are relatively movable. The end of the spool 2 is connected to the plug 5.
The stopper portion 8 is a step formed between the spool 2 and the plug 5 at this portion.

Further, a pressure receiving chamber 9 is formed between the spring receiver 6 and the spool 2, and the pressure receiving chamber 9 is connected to a pilot port 11 formed in the cap 3 through a through hole 10 formed in the spring receiver 6. It's communicating.

The reason why the pressure receiving chamber 9 is communicated with the pilot port 11 side through the through hole 10 is to make the pilot pressure introduced into this pilot chamber 4 act on this pressure receiving chamber 9 as well, thereby improving the responsiveness of the spool 2. It's for a reason.

Further, a centering spring 12 is interposed between the spring receiver 6 and the inner wall surrounding the pilot port 11 of the cap 3. And, due to the action of this centering spring 12,
When the spring receiver 6 is pressed against the main body 1 side as shown, the outer periphery of the center hole 7 comes into contact with the stopper part 8, and in this position, the spool 2 is held in a neutral position.

In the above description, only the structure of one side of the spool 2 was explained, but the structure of the opposite side (not shown) is also the same as above.

Thus, when pilot pressure is introduced into the pilot chamber 4 from the illustrated state, that pressure is introduced into the pressure receiving chamber 9 as well as the pilot chamber 4. Therefore, the spool 2 moves in the direction of the arrow 13 due to the pressure action, but at this time the spring receiver 6 remains in the illustrated position. Then, when the pressure in the pilot chamber 4 decreases, the spool 2
is returned to the neutral position by the action of a centering spring provided in a pilot chamber (not shown) opposite to the pilot chamber 4 (not shown).

Furthermore, when pilot pressure is introduced into the pilot chamber on the opposite side, the spool 2 moves in the opposite direction to the arrow 13, but at this time, the spring receiver 6 hits the stopper part 8, so the spool 2 moves into the spring receiver. 6 and compresses the centering spring 12. When the pressure in the pilot chamber on the opposite side decreases, the spool 2 is moved by the spring action of the centering spring 12.
is pushed back to the neutral position.

(Problems to be Solved by the Present Invention) The conventional spool valve as described above does not have a speed control mechanism when the spool 2 returns, so the pilot pressure in the pilot chamber 4 drops rapidly. At this time, the return speed of the spool 2 becomes extremely fast. Furthermore, if the through hole 10 is formed to improve the responsiveness of the spool 2, the cushioning function of the spring receiver 6 will be impaired.
When does the return speed of the spool 2 become so fast?

If the return speed of the spool 2 becomes too fast as described above, there is a problem that, for example, the shock when the actuator connected to the spool valve is stopped becomes large. In particular, as mentioned above, in order to improve responsiveness when switching the spool valve, the through hole 10
If the actuator is formed, the return speed of the spool 2 becomes faster, so there is a problem that the shock when the actuator stops becomes larger.

The purpose of this invention is to provide a speed control mechanism that not only controls the speed of the spool when it returns to its neutral point, but also improves the responsiveness when switching the speed.

(Means for solving the problem) This invention has both ends of the spool facing the pilot chamber, a spring receiver is provided at the end of the spool facing the pilot chamber, and the spring of the centering spring acts on the spring receiver. This method is based on a pilot spool valve configured to maintain the spool in a neutral position by force.

Based on the above pilot spool valve, the speed control mechanism of this invention inserts both ends of the spool into the spring receiver so as to be movable relative thereto, and the spring receiver is provided with a position in which the spool is moved. A control port is formed whose opening degree is controlled accordingly, and a poppet slidably inserted into the end of the spool opens and closes the seat formed in the spring receiver, and the control port and the seat in the spring receiver are connected to each other. A cushion chamber is formed between the passages connecting the cushion chambers, and the cushion chamber is characterized in that a restriction is formed in the cushion chamber to provide resistance when the fluid inside the cushion chamber flows out.

(Operation of the present invention) Since the present invention is configured as described above, when the spool returns from the switching position to the neutral position, the control port formed in the spring receiver is gradually closed by the spool. When the control port is closed in this manner, the fluid in the cushion chamber flows out through the restriction formed in the cushion chamber, thereby slowing down the return speed of the spool.

Further, when the spool is switched by applying pressure to the pilot chamber, the poppet opens, so that the pilot pressure receiving area of the spool can be kept sufficiently large.

(Effects of the present invention) According to the return speed control mechanism of the pilot spool valve of this invention, the opening degree of the control port is controlled according to the movement of the spool. The stop shock of the actuator at the time of return can be alleviated.

(Embodiment of the present invention) In the first embodiment shown in FIG.
The end is coming. A plug 18 is fitted to the end of the spool 17, and the end of the plug 18 is made hollow, and a poppet 19 is slidably inserted into the hollow part.

Further, a spring receiver 20 is installed inside the pilot chamber 16;
0 has a large diameter part 20a and a small diameter part 20b, and a centering spring 2 is provided at a step part 20c formed at the boundary between the large diameter part and the small diameter part.
1 is acting.

The large diameter portion 20a of the spring receiver 20 configured as described above has an inner diameter larger than the outer diameter of the spool 17, and has a pressure receiving chamber 22 between it and the spool 17.
is formed. A through hole 23 is formed in this large diameter portion 20a, and the pressure receiving chamber 22 is connected to the cap 1.
It communicates with the pilot port 24 side formed at 5. In addition, the small diameter portion 20b of the spring receiver 20
The plug 18 is slidably inserted into the small diameter portion 20b, and a control port 25 whose opening degree is controlled according to the movement position of the spool 17, that is, the plug 18 is formed in the small diameter portion 20b. This control port 25 is closed with a plug 18 when the spool 17 is in the neutral position shown;
It opens when it moves in the direction of arrow 26.

The terminal end of the spool 17 has a larger diameter than the plug 18, and a step formed between the spool 17 and the plug 18 at this portion is a stopper portion 27. When the spring receiver 20 is pressed against the main body 14 side as shown in the figure by the action of the centering spring 21, the inside of the step portion 20c comes into contact with the stopper portion 27, and the spool 17 is held in this position. It is held in a neutral position.

The tip of the spring receiver 20 has a thick wall portion 2.
8 is formed, and this thick portion 28 has a communication hole 29 penetrating in a direction perpendicular to the axis, and a communication hole 29 formed therein.
A port 30 is formed perpendicular to the port 30, and a seat portion 31 is formed at the inner end of the port 30.

A poppet 19 is in pressure contact with the seat portion 31, and a throttle 32 is formed in the poppet 19, and this throttle 32 is communicated with a cushion chamber 34 inside the spring receiver 20 through a communication hole 33. There is.

When pilot pressure is introduced from the pilot port 24, the poppet 19 is moved back and the seat portion 31 is opened by the action of the pilot pressure, so that the pilot pressure acts on the end face of the plug 18. Furthermore, since the pilot pressure is also guided from the through hole 23 to the pressure receiving chamber 22, the pilot pressure also acts on the end surface of the spool 17 in this pressure receiving chamber. If pilot pressure acts on the spool in this way, spool 1
7 moves in the direction of arrow 26 while being repelled by the centering spring on the opposite side and switches.

When the pilot pressure is introduced into the pilot chamber 16 in this way, the poppet 19 moves and opens the seat portion 31, so that the pilot pressure is applied not only to the end of the spool 17 facing the pressure receiving chamber 22 but also to the end of the poppet 18. In other words, since the pilot pressure acts on the entire surface of the spool end including the poppet, the responsiveness of the spool 17 becomes very good.

However, even if the spool 17 moves in the direction of the arrow 26, the spring receiver 20 remains in contact with the main body 14 and maintains the illustrated position. Therefore, the spool 17, the plug 18, and the spring receiver 20 move relative to each other, and the control port 25 is opened.

When the pressure in the pilot chamber 16 is rapidly reduced in the above state, the spool 17 returns to the neutral position by the action of the centering spring on the opposite side, and the poppet 19 comes into pressure contact with the seat part 31 by the action of the spring 35. Close port 30.

Further, as described above, in the process of returning the spool 17 to the neutral position, the plug 18 gradually closes the control port 25, but when the control port 25 is closed in this way, the outflow port of the cushion chamber 34 is restricted. As a result, the return speed of the spool 17 becomes slower.

When the control port 25 is completely closed, the throttle 32 is the only outflow port of the cushion chamber 34, so the outflow resistance increases and the return speed of the spool 17 becomes slower.

As described above, according to the first embodiment, when the spool 17 is switched, the pilot pressure is applied to the entire surface of the spool end, so that the response is very good. Further, when the spool 17 returns to the neutral position, the control port 25 is gradually closed and the return speed is finally regulated by the action of the throttle 32.

In the second embodiment shown in FIG. 2, the control port is
It is composed of three ports 25a to 25c. That is, these first to third control ports 25a
~25c has its opening diameter gradually reduced as it goes outward.

When the spool 17 is moved in the direction of the arrow 26 by applying pilot pressure to the pilot chamber 16, it is exactly the same as in the first embodiment.
However, when the spool 17 returns to the neutral position, it gradually closes from the first control port 25a to the third control port 25c, so the outlet in the cushion chamber 34 also gradually closes. The return speed of the spool 17 will be regulated.

In the third embodiment shown in FIG. 3, an annular groove 36 is formed on the outer periphery of the plug 18, and an oil passage hole 37 communicating with the cushion chamber 34 is formed at the outer end of the annular groove 36.

Further, communication holes 38 and 39 are formed in the small diameter portion 20b of the spring receiver 20, and a control port 25 is formed between these communication holes 38 and 39.

However, in this third embodiment, the spool 17
In the process of returning to the neutral position, both flow holes 3
Control port 25 only when ports 8 and 39 are closed.
Eventually, at the intermediate position of the return stroke of the spool 17, the control port 25
functions and slows it down.

The fourth embodiment shown in FIG. 4 is similar to the first embodiment except that the aperture 32 formed on the poppet 19 in the first to third embodiments is formed on the spring receiver 20.

In addition, the poppet 1 in the above first to third embodiments
It goes without saying that the aperture 32 formed at 9 may be formed by a slit.

Further, in each of the above embodiments, the spool 17 and the plug 18 are expressed as separate entities, but the concept of the spool of this invention includes the above-mentioned plug.

[Brief explanation of drawings]

1 to 4 are sectional views of the main parts of the first to fourth embodiments of this invention, and FIG. 5 is a sectional view of the main parts of a conventional spool valve. 16...Pilot chamber, 17...Spool, 2
0... Spring receiver, 21... Centering spring, 25... Control port, 25a to 25c
...1st to 3rd control ports, 31... Seat part, 3
2...Aperture, 34...Cushion chamber.

Claims (1)

[Scope of utility model registration request] Both ends of the spool face the pilot chamber, and a spring receiver is provided at the end of the spool facing the pilot chamber, and the spring force of the centering spring acting on this spring receiver allows
In a pilot spool valve configured to hold the spool in a neutral position, both ends of the spool are inserted into the spring receiver so as to be movable relative thereto, and the spring receiver includes:
A control port is formed whose opening degree is controlled according to the moving position of the spool, and a poppet slidably inserted into the end of the spool opens and closes a seat formed in the spring receiver. A cushion chamber is formed between the passage connecting the control port and the seat part, and
A return speed control mechanism for a pilot spool valve is formed in the cushion chamber to provide resistance when the fluid in the cushion chamber flows out.