JPH024241Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an operating circuit device for a logic valve.
The applicant previously proposed a system in which a logic valve having a seat-type valve structure is interposed in the hydraulic circuit of a free forging press, etc., and the opening and closing of the logic valve is further controlled by a separate logic valve. 1977-
No. 46102). In this case, as shown in the first diagram, the hydraulic circuit a
A pressure chamber c behind the main logic valve b is connected to a hydraulic circuit h in front of the main logic valve b via a first pilot circuit e with a throttle d interposed therebetween, and a second pilot circuit with an auxiliary logic valve f interposed therebetween. Connect to the hydraulic circuit i behind the main logic valve b via g,
The opening and closing of the main logic valve b is controlled as much as possible by controlling the opening and closing of the auxiliary logic valve with the fluid pressure of the front hydraulic circuit h. When the pressure becomes higher than the pressure in the front hydraulic circuit h, the main logic valve b opens and a backflow occurs in the hydraulic circuit a, so it was necessary to interpose the check valve j in the hydraulic circuit a. Therefore, the check valve j interposed in the hydraulic circuit a through which a relatively large flow rate must be of a relatively large diameter.
This has the disadvantage that the space occupied by the check valve j becomes large.

The present invention aims to solve these drawbacks, and includes a main logic valve 2 that controls communication between the hydraulic circuit 1 and the pressure chamber 2a behind the main logic valve 2. It is connected to the hydraulic circuit 1a in front of the main logic valve 2 via an intervening first pilot circuit 4, and connected to the hydraulic circuit behind the main logic valve 2 via a second pilot circuit 6 with an auxiliary logic valve 5 interposed therebetween. 1b, and further connects the pressure chamber 5a behind the sub logic valve 5 to the front hydraulic circuit 1a via the third pilot circuit 11, and connects the pressure chamber 5a of the rear pressure chamber 5a to the third pilot circuit 11. A switching valve 9 is provided to control the pressure between the pressure of the front hydraulic circuit 1a and the pressure of the tank 10, and the opening/closing operation of the main logic valve 2 is performed by both pilot circuits 4 and 6. The hydraulic circuit 1b is connected to the rear pressure chamber 2a through a check valve 7 that allows the fluid pressure of the rear hydraulic circuit 1b to be introduced, and the front hydraulic circuit 1a is connected to the first pilot circuit 4. A check valve 8 is interposed to allow fluid pressure to be introduced.

FIG. 2 shows an example of this. When the valve body of the main logic valve 2 is pressed against the seat by the pressure of the pressure chamber 2a behind it and the spring, the hydraulic circuit 1 is cut off, and the pressure chamber 2a behind the valve body is pressed against the seat. When the pressure is low, hydraulic circuit 1
The valve body is pushed up against the spring by the pressure of the hydraulic circuit 1, and the sub logic valve 5
The second pilot circuit 6 also has substantially the same configuration as this, and the communication of the second pilot circuit 6 is controlled by opening and closing it.

In the illustrated example, one end of the third pilot circuit 11 is connected between the check valve 8 of the first pilot circuit 4 and the throttle 3, and the operation of the switching valve 9 interposed in the third pilot circuit 11 causes the secondary The pressure of the front hydraulic circuit 1a is introduced into the pressure chamber 5a behind the logic valve 5 via the first pilot circuit 4, or the pressure of the pressure chamber 5a is discharged to the tank 10, and the sub logic valve 5 The opening/closing control of the second pilot circuit 6 is performed by the following.

Next, its operation will be explained.

When the switching valve 9 is in the second illustrated position 9a, the pressure of the hydraulic circuit 1a in front of the main logic valve 2 acts on the pressure chamber 5a of the auxiliary logic valve 5 via the first and third pilot circuits 4 and 11. Therefore, the second pilot circuit 6 is closed, and at the same time, the pressure of the front hydraulic circuit 1a acts on the pressure chamber 2a of the main logic valve 2, so that the valve body of the main logic valve 2 is pressed against the seat and the hydraulic circuit is closed. Cut off communication with 1. When the switching valve 9 is switched to position 9b, the pressure chamber 5 of the sub logic valve 5
Since a is connected to the tank 10, the sub logic valve 5 opens the second pilot circuit 6, and the main logic valve 2 opens because its pressure chamber 2a is connected to the lower pressure hydraulic circuit 1b, and the main logic valve 2 is opened to connect the pressure chamber 2a to the lower pressure hydraulic circuit 1b. Fluid flows to 1b. If the pressure in the hydraulic circuit 1b behind the main logic valve 2 increases while the main logic valve 2 is shutting off the hydraulic circuit 1, the pressure is transferred to the pressure chamber 2a of the main logic valve 2 via the check valve 7. Moreover, the pressure is prevented from being transmitted to the front hydraulic circuit 1a by the check valve 8 of the first pilot circuit 4, so the main logic valve 2 does not open, and the hydraulic circuit is closed as before. There is no need to interpose a large check valve in 1.

In this way, according to the present invention, it is possible to introduce the rear hydraulic circuit 1b into the pressure chamber 2a of the main logic valve 2 via the check valve 7, and the first pilot circuit 4
Since a check valve 8 for blocking pressure transmission from the pressure chamber 2a to the front hydraulic circuit 1a is provided, the hydraulic circuit 1
Backflow can be prevented in the main logic valve 2 without providing a check valve in the main logic valve 2, and the check valves 7 and 8 are small and simple because they are installed at a location connected to the pressure chamber 2a through which only a small amount of flow flows. It has the advantage of being easy to install, occupying a small space, and being easy to install.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a conventional example, and FIG. 2 is a diagram of an embodiment of the present invention. 1, 1a, 1b...hydraulic circuit, 2...main logic valve, 2a...pressure chamber, 3...throttle, 4...first
Pilot circuit, 5... Sub logic valve, 6... Second pilot circuit, 7, 8... Check valve.

Claims (1)

[Scope of utility model registration request] A main logic valve 2 for controlling communication between the hydraulic circuit 1 and the main logic valve 2 is interposed in the hydraulic circuit 1, and the pressure chamber 2a behind the main logic valve 2 is connected to the main logic valve 2 through the first pilot circuit 4 with the throttle 3 interposed. Front hydraulic circuit 1
a, and is also connected to the hydraulic circuit 1b behind the main logic valve 2 via the second pilot circuit 6 with the sub logic valve 5 interposed, and furthermore, the pressure chamber 5a behind the sub logic valve 5 is connected to the third pilot circuit 6. Pilot circuit 1
1 to the front hydraulic circuit 1a, and controls the third pilot circuit 11 to control the pressure in the rear pressure chamber 5a to the pressure in the front hydraulic circuit 1a and the pressure in the tank 10. in which the main logic valve 2 is opened and closed by both pilot circuits 4 and 6, and the rear pressure chamber 2 is
a into the hydraulic circuit 1 through a check valve 7 that allows the fluid pressure of the rear hydraulic circuit 1b to be introduced into the hydraulic circuit 1b.
A logic valve operating circuit device comprising a check valve 8 which is connected to the first pilot circuit 4 and which allows the fluid pressure of the front hydraulic circuit 1a to be introduced into the first pilot circuit 4.