JPH0131067B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention interposes a cylinder circuit that connects a hydraulic pump and a hydraulic cylinder to switch the supply and locking of pressure oil to the cylinder as well as the discharge of pressure oil from the cylinder. , related to pressure oil supply/blocking/discharge switching valves for cylinder circuits.

Conventionally, in a cylinder circuit, a locking circuit as shown in Fig. 1 is interposed between a cylinder 1 and a hydraulic pump 2 as a device for switching between supplying and blocking pressure oil to the cylinder and discharging pressure oil from the cylinder. is customary.

However, in this case, since the pressure oil supply/discharge switching valve 3' is configured with a port type valve, the cylinder internal pressure decreases due to internal wetting of the switching valve 3', and reliable locking cannot be maintained for a long time. It is difficult to do so.

In such a locking circuit, in order to maintain reliable locking for a long period of time, it is normal to continue operating the hydraulic pump 2 without interruption during the locking period.

However, in today's energy crisis, it is imperative to stop hydraulic pumps as much as possible during the locking period to conserve valuable energy.

In order to meet such demands, the present inventor formed two valve chambers 6', 6'' in the valve box 5', as shown in FIG. Return port 7' to one end of the other valve chamber 6'',
A load port 9' is connected to each other end of both valve chambers 6', 6'', and a seat valve-type leakage prevention valve body 10' that opens and closes a pressure port 7' is provided in one valve chamber 6'. A seat valve type drain valve body 11' that opens the return port 8' is inserted into the other valve chamber 6'', and each valve closing spring 13', 1
3" to press each valve body 10', 11' to the valve closing position,
The leakage prevention valve body 10' can be opened against the valve closing spring 13' by the hydraulic pressure supplied from the pressure port 7', and the drain valve body 11' is closed by the internal pressure of the valve chamber 6'' by the valve opening device 14'. Valve spring 1
The present invention has been conceived in such a way that, at the same time as the valve is opened against pressure 3", the valve closing device 14" closes the leakage prevention valve body 10' against the hydraulic pressure supplied from the pressure port 7'.

However, in this configuration, the two valve chambers 6', 6'',
Since two valve closing panels 13', 13'', a valve opening device 14' and a valve closing device 14'' are required, the number of parts is relatively large, the structure is complex and large, and it tends to lack compactness. There is.

In view of the above points, the present invention is capable of maintaining reliable locking for a long period of time, meets society's urgent need for energy conservation, and has a relatively small number of parts, a simple structure, and a small and compact design. This was proposed for the purpose of providing a pressure oil supply/blocking/discharge switching valve for a cylinder circuit.

Hereinafter, the structure and operation of the present invention will be explained through illustrated embodiments.

FIG. 3 shows a hydraulic circuit for a hydraulic clamp and die lifter attached to a mechanical press, in which an upper clamp cylinder 1a, a lower clamp cylinder 1b, and a die lifter cylinder 1c are connected in parallel to an air-driven hydraulic pump 2. , each cylinder 1
A pressure oil supply/blocking/discharge switching valve 3 is interposed between a, 1b, 1c and the hydraulic pump 2.

Reference numeral 4 indicates an oil pan.

As shown in FIG. 4, each switching valve 3 has a pressure port 7 at one end of the valve chamber 6 in the valve box 5, a return port 8 at the opposite end, and a load port 9 between both ends. A seat valve-shaped leakage prevention valve body 10 that opens and closes the pressure port 7 in the valve chamber 6 and a seat valve-shaped drain valve body 11 that opens and closes the return port 8 are connected in series with a gap 12 between them. Arrange in a shape.

A valve closing spring 13 is inserted between the valve bodies 10 and 11 to press each valve body 10 and 11 to the valve closing position.

Incidentally, reference numeral 15 in FIG. 4 is an oil passage groove.

When the hydraulic pump 2 is operated and the hydraulic oil pumped up from the oil pan 4 is supplied at a predetermined pressure (70 to 250 kg/cm ² ), as shown in Fig. 5, the oil pressure supplied from the pressure oil port 7 prevents leakage. When the valve body 10 is pushed open against the valve closing spring 13 and the pressure in the oil passage from the cylinder to the valve chamber 6 becomes approximately equal to the supplied hydraulic pressure, the flow prevention valve body 10
is automatically closed by the valve closing spring 13 and automatically shifts to the closed state.

In the closed state, both the valve bodies 10 and 11 are pressed to the closed position by the internal pressure of the valve chamber 6 and the valve closing spring 13, so that the hydraulic fluid does not flow to the pressure port 7 side or the return port 8 side. It will not leak.

Incidentally, an annular sealing member 16 made of synthetic resin is embedded in the valve surfaces of both the valve bodies 10 and 11, and this sealing member 16 is brought into contact with the annular contact portion 18 of the valve seat 17 to inject pressure oil. It's becoming more and more disconcerting.

The outer periphery of the valve surface is caulked to the sealing member 16 to prevent the valve bodies 10 and 11 from falling off, and the sealing member 16 prevents abrasion of the contact portion 18. .

Valve opener 14 for opening the drain valve body 11
may be manual or hydraulic, but in this example it is pneumatically driven.

That is, the valve opening device 14 includes a cylinder case 19 in the form of a cylinder with a lid fixed to the return port 8 side of the valve box 5, a piston 20 inserted into the cylinder case 19 in an airtight and slidable manner, and a cylinder by the piston 20. A pressure receiving chamber 21 defined on the lid side of the case 19, and a return spring 2 that presses the piston 20 toward the pressure receiving chamber 21 side.
2 and a valve opening pin 23 protruding from the piston 20 to the return port 8, the pressure receiving chamber 21 is filled with compressed air, the piston 20 is advanced toward the valve box 5 side against the return spring 22, and the valve opening pin 23 into the valve chamber 6 through the return port 8, the drain valve body 11
is pushed open against the internal pressure of the valve chamber 6 and the valve closing spring 13.

If the drain valve body 11 is opened even slightly, the internal pressure of the valve chamber 6 will drop rapidly, and the drain valve body 11 will be fully opened in an instant, and the valve opener 14 will open as shown in FIG.
Then, the flow prevention valve body 10 is pushed closed via the drain valve body 11 against the hydraulic pressure supplied to the pressure port 7.

As a result, when the drain valve body 11 is opened to discharge pressure oil from the valve chamber 6 to the drain passage (reference numeral 24 in FIG. 3), the hydraulic oil does not leak from the pressure port 7 to the return port 8. The hydraulic pressure supplied to the pressure port 7 does not suddenly drop and the hydraulic pressure supplied to other hydraulic circuits connected in parallel with the switching valve 3 does not decrease, and for example, when discharging pressure oil from the die lifter cylinder 1c, The upper mold does not fall off due to loosening of the mold clamper cylinder 1a, and the die lifter does not fall unexpectedly when discharging pressure oil from both the upper and lower mold clamper cylinders 1a, 1c.

In FIG. 3, reference numeral 25 represents each pressure switch,
This is closed when the internal pressure of each cylinder 1a, 1b, 1c falls below a predetermined value, and is an electromagnetic on-off valve (not shown) interposed between the compressed air supply source (not shown) and the compressed air supply circuit 26. ) is opened and the hydraulic pump 2 is operated. Although not shown, each cylinder 1a, 1b, 1c and each switching valve 3
An overload safety valve or temperature compensation valve is connected between the two as necessary. These overload safety valves and temperature compensation valves may be connected to the valve chamber 6.

Further, in FIG. 3, the reference numeral 27 indicates a valve opening control valve, and in FIGS. 4 to 6, the reference numeral 28 indicates an oil filter.

Since the present invention is configured and operates as described above, it achieves the following effects (a) to (e).

(a) Since the leakage prevention valve body and the drain valve body are made into seat valve shapes, and both valve bodies are pressed to the closed position by the valve closing spring and the internal pressure of the valve chamber, there is no internal leakage of the switching valve.
Reliable circuit locking can be performed for a relatively long period of time.

(b) There is no drop in cylinder internal pressure due to internal leakage of the switching valve, and the hydraulic pump can be stopped during the locking period, resulting in significant energy savings.

(c) When discharging pressure oil from the cylinder, use the valve opener to push and close the leakage prevention valve element via the drain valve element.
It can reliably prevent leakage from the pressure port to the return port.
It is possible to reliably prevent a pressure drop in the hydraulic circuit connected in parallel to the switching valve, as well as unexpected operations and accidents caused by this.

(d) Even if the hydraulic pressure supplied to the pressure port drops for some reason, the leakage prevention valve will not open, so the internal pressure in the cylinder or valve chamber connected to the switching valve will not drop. A reliable locking action can be maintained.

(e) The valve chamber is one chamber, the valve closing spring is one,
In addition, since the valve opener pushes and closes the leakage prevention valve element via the drain valve element, and there is no separate valve closure device that pushes and closes the leakage prevention valve element, the number of parts is relatively small and the structure is simple. Easy, small and compact.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional hydraulic cylinder equipped with a known locking circuit, and FIG. Figures 3 to 6 show one embodiment of the present invention, Figure 3 is a hydraulic circuit diagram for a hydraulic clamp and die lifter attached to a mechanical press, and Figure 4 is a diagram of the pressure oil supply/blocking/discharge switching valve. A vertical cross-sectional view, FIG. 5 is an oil flow path diagram inside the switching valve when pressure oil is supplied, and FIG. 6 is an oil flow path diagram inside the switching valve when pressure oil is discharged. 5...Valve box, 6...Valve chamber, 7...Pressure port, 8...
...Return port, 9...Load port, 10...Escape prevention valve body, 11...Drain valve body, 12...Gap, 13...
... Valve closing spring, 14... Valve opening device.

Claims (1)

[Claims] 1 A seat valve type in which a pressure port 7 is provided at one end of the valve chamber 6 in the valve box 5, a return port 8 is provided at the opposite end, and a load port 9 is provided between both ends, and the pressure port 7 is opened and closed. A leakage prevention valve body 10 and a seat valve-shaped drain valve body 11 that opens and closes the return port 8 are placed in the valve chamber 6 with a gap 12.
A valve closing spring 13 is inserted between both valve bodies 10 and 11 to press each valve body 10 and 11 to the closed position, and the hydraulic pressure supplied from the pressure port 7 prevents leakage. The valve body 10 is made openable against the valve closing spring 13,
The drain valve body 11 is configured to be able to be pushed open toward the pressure port 7 side by the valve opener 14 against the valve closing spring 13 and the internal pressure of the valve chamber 6, and when the drain valve body 11 is pushed open, the valve opener Pressure oil supply/blocking/discharge switching valve for a cylinder circuit, characterized in that the flow prevention valve body 10 is pressed and closed via the drain valve body 11 at 14 against the supply hydraulic pressure of the pressure port 7. .