JPS5936151B2 - switching valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a 5-port, 3-position exhaust center type switching valve used for switching and controlling the reciprocating motion of a pneumatic cylinder.

1-Prior art" Conventionally, this type of switching valve has been disclosed in Japanese Patent Application Laid-Open No. 52-15081
, No. 8 is known.

To summarize this with Figures 3 and 4, it is imported into the central part of the valve body ■ that forms the spool chamber C6.
On the left and right are the left and right outports A.

B Furthermore, on the left and right are the left and right exhaust ports R,,R
In addition, left and right pilot chambers C1 and C2 are provided at both left and right ends of the spool chamber C8, and these spool chambers C
6. A pair of left and right spools S0 in the pilot chambers C1 and C2
．． S2 is slidably fitted.

These spools have a land portion D at their inner end and a piston E having a larger diameter than the land portion at their outer end.
The land part fits into the spool chamber Co and slides in a range beyond the outboard A or B to the left and right, and the piston E fits into the pilot chamber C1 or C2 and slides therein.

Left and right pilot electromagnetic valves of so-called internal pilot type are attached to the outside of the left and right pilot chambers C1 and C2.

``Problems to be Solved by the Invention'' However, with this conventional system, as shown in FIG. The left and right ports of cylinder F are connected respectively, and the variable exhaust throttle valve G1. G
2 are connected and the displacement of the pneumatic cylinder F is adjusted using these throttle valves to control the speed of its reciprocating motion, the following drawbacks arise.

That is, when the switching valve is switched from the state shown in FIG. 3 to the state shown in FIG. 4 in order to reverse the reciprocating motion of the pneumatic cylinder F, the right spool S2 moves to the left and its land portion touches the outport 1-B. exceed.

At this time, there is an outpaw 1-B on the right side of the land area.
The air pressure from the import P acts on the left side of the piston E, and the air pressure from the import P acts on the A5jJ11 surface of the piston E through the pilot solenoid valve on the right side. , Since exhaust port R2 is constricted, air pressure from outport B is applied.

Therefore, the left and right air pressures acting on the right spool S2 are balanced, and its movement becomes slow.

This is similar to the case with the left spool S1, which has the disadvantage that the switching operation of the reciprocating motion of the pneumatic cylinder F becomes slow.

The present invention aims to eliminate such drawbacks.

[Means for Solving the Problems] A feature of the present invention is that an auxiliary land portion having the same diameter as the land portion is provided between the piston and the land portion at the inner end of each of the pair of spools. In order for this auxiliary land to fit into the spool chamber and slide on the outside of the exhaust port, the distance between the auxiliary land and the piston should be adjusted according to the distance between the inner stroke end position of the pilot chamber and the exhaust port. The valve body is further provided with a breather that communicates with the space formed between the auxiliary land portion and the piston.

"Operation" Therefore, according to the present invention, when the land portion at the inner end crosses the out port, the pressure on the spool that is generated due to the narrowed exhaust port, that is, the pressure on the spool that acts on the piston from inside and reduces its sliding. Since the pressure that suppresses the movement can be blocked by the auxiliary land, the left and right air pressures acting on the spool are balanced and the movement does not become slow as in the conventional case.

"Example" An example of the present invention will be described below in detail based on FIGS. 1 and 2.

In FIG. 1, the valve body 1 installed on the base 7 is
Left and right pilot chambers 3 and 4 having an inner diameter larger than this are formed at both left and right ends of the spool chamber 2, and these pilot chambers 3
, 4 are closed with covers 5, 6.

The valve body 1 has five ports that communicate with the spool chamber 2, namely, an import port 1-8 in the center, left and right out ports 1-9, 10 on the left and right, and left and right exhaust ports [1, 12] on the left and right. It is perforated.

The left and right out ports 1-9 and 10 communicate with left and right out passages 9' and 10' provided in the base 7, respectively.

□ Inside the valve body 1, a pair of left and right spools 13 and 14 are fitted in opposite directions to each other and separately slidable left and right.

That is, each of the spools 13 and 14 has a main land portion 15 slidably fitted into the spool chamber 2 at its inner end, and a pilot chamber having a larger diameter than the main land portion 15 at its outer end. A piston 16 is slidably fitted into the pistons 3 and 4, respectively, and is further slidably and movably fitted into the spool chamber 2 with the same diameter as the main land portion 15 midway between the main land portion 15 and the piston 16. An auxiliary land portion 1γ is provided.

The main land portion 15, the piston 16, and the auxiliary land portion 17 are all provided with packing on their outer peripheral surfaces.

Each of the spools 13 and 14 is located at an inner stroke end position where the inner side of the piston 16, that is, the collar 18 engages with the boundary steps 19 and 20 between the spool chamber 2 and the pilot chambers 3 and 4, respectively, as shown in FIG. As shown in FIG. 2, the outer ends 13' and 14' can slide within the range of outer stroke end positions in which they engage the inner surfaces of the left and right covers 5 and 6, respectively.

The main land portion 15 is connected to the left and right out ports 9,
10 to the left and right, but the auxiliary land portion 17 is such that the distance between it and the piston 16 (specifically, the collar 18) is the same as that between the exhaust port 11.12 and the boundary step portion 19.
．． 20, so the exhaust port 1-
It slides on the left and right outside of ICl3 without exceeding it.

Pilot pressure (supply pressure from the import 8) is supplied to the left and right pilot chambers 3 and 4 through internal pilot type pilot solenoid valves 2L22 attached to the outside of the cover 5゜6. Ru.

On the other hand, the spaces between the pistons 16 of the left and right spools 13 and 14 and the auxiliary land portions 1γ are opened to the atmosphere by left and right breathers 25 and 26 provided on the valve body 1, respectively.

This switching valve operates as follows.

When both pilot solenoid valves 21 and 22 are opened and pilot pressure is supplied to both pilot chambers 3 and 4, as shown in FIG.
14 is set at the inner stroke end position, and the left out port 9 and the left exhaust port 11 are
Main land portion 15 and auxiliary land portion 1 of the left spool 13
The right outport 10 and the right exhaust port 12 communicate with each other through an annular space 23 between them.
are in communication through an annular space 24 between the main land portion 15 and the auxiliary land portion 17 of the right spool 14.

On the other hand, when no pilot pressure is applied to either of the pilot chambers 3 or 4, both spools 1
3 and 14 are both set at the outer stroke end position by the supply pressure sent through the inlet 8, and the left and right outports 9 and 10 communicate with the inlet 8.

Furthermore, if pilot pressure is supplied to only one of the left and right pilot chambers 3 and 4, the left and right spools 13 and 14
0 is set to the inner stroke end position, and the other is set to the outer stroke end position.

By the way, if a variable exhaust throttle valve is connected to the outside of the exhaust bow (exhaust bow) 11, 120 to perform exhaust throttling, the left out port 1-9 and the left exhaust port 11 are connected as shown above. Furthermore, when the right out port 10 and the right exhaust port 12 communicate with each other, the fluid pressure in the annular chambers 23 and 24 simultaneously acts on the side surfaces of the main land portion 15 and the auxiliary land portion 17, which have the same diameter. , the pressure-receiving areas of the side surfaces of both land portions 15 and 17 are the same, and the pressure does not act on the piston 16 as it is blocked by the auxiliary land portion 1γ.
Since the space of the auxiliary land portion 17 is opened to the atmosphere by the breathers 25 and 26, the spools 13 and 14 are retracted inwardly by the pylon I pressure (supply pressure from the inboard 8) acting on the piston 16. is pushed to.

I-Effects of the Invention As shown above, according to the switching valve of the present invention, even when exhaust throttle is performed by connecting an exhaust variable throttle valve to the exhaust bow 1, the spool can be moved inward by the pilot pressure without any trouble. Since it can be pushed in the opposite direction, it is suitable as a meter-out control switching valve that adjusts the displacement of the pneumatic cylinder and controls the speed of its reciprocating motion.

[Brief explanation of the drawing]

Figures 1 and 2 show an embodiment of the present invention. Figure 1 is a sectional view with both spools biased inward, and Figure 2 is a sectional view with both spools biased outward. , Fig. 3 is a sectional view of the conventional example, Fig. 4 is an explanatory diagram of its operation, and Fig. 5 is a sectional view of the conventional example.
The figure is a pneumatic circuit diagram showing an example of its use. 8... Inboard, 9, 10... Left and right out ports, 11, 12... Left and right exhaust ports, 1... Valve body, 2.・・・・・・
Spool room, 3, 4... Left and right pilot rooms,
15... Main land part, 16... Piston, 13, 14... Left and right spools, 17...
...Auxiliary land part, 25, 26...Left and right breathers.

Claims (1)

[Claims] 1. Left and right pilot chambers are provided at both the left and right ends of the spool chamber of the valve body, which has an import in the center, left and right out ports on the left and right, and left and right exhaust ports on the left and right. Left and right 1 with a piston larger in diameter than this land at the outer end.
Slide the pair of spools with their land portions fitting into the spool chamber to the left and right beyond the outer port,
In addition, in a switching valve that is separately fitted in a valve body so as to be slidable left and right so as to fit into a piston high rod chamber and slide between an inner stroke end position and an outer stroke end position therein, For each of the pair of spools, an auxiliary land portion having the same diameter as the land portion is provided between the piston and the land portion at the inner end, and the auxiliary land portion is fitted into the spool chamber to form the exhaust pipe. Poe 1
The distance between the auxiliary land and the piston is made shorter than the distance between the inner stroke end position and the exhaust port, and the auxiliary land is placed on the valve body so that the auxiliary land slides on the outside without exceeding the length Q. A switching valve characterized by being provided with left and right breathers that communicate with a space formed between a portion and a piston.