JPS6340990B2 - - 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, internal leakage of the switching valve 3' causes a drop in the cylinder internal pressure, making it difficult to maintain reliable blocking 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 opened by the valve opening device 14' due to the internal pressure of the valve chamber 6'' and closed. 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 springs 13', 13'', a valve opener 14' and a valve closer 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 addition, since the drain valve body 11' receives the internal pressure of the valve chamber 6'' over the entire opening area of the return port 8', the valve opening device 14' that opens the drain valve body 11' has a relatively large output and is large. I have a tendency to become

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 structure. , 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 return port 8 is provided in the drain valve body 11 along its axis.
A pressure relief valve body 18 in the form of a seat valve that opens and closes the pressure relief passage hole 15 and a valve closing spring 13 are arranged in series between the two valve bodies 10 and 11 through a pressure relief passage hole 15 having a diameter smaller than that of Insert into.

Here, a pressure relief valve chamber 16 is provided between a side surface of the return port 8 of the diverting prevention valve body 10 and a side surface of the pressure port 7 of the drain valve body 11.
By making the pressure relief valve body 18 recessed and inserting the pressure relief valve body 18 into the pressure relief valve chamber 16 so as to be able to advance and retreat, the gap 12 between the flow prevention/drain valve bodies 10 and 11 is made as small as possible, and the switching valve 3 has a small and compact structure as a whole, but this is not an essential structure for the present invention.

In addition, a spring seat hole 17 is recessed on the side surface of the return port 8 of the leakage prevention valve body 10 and the side surface of the pressure port 7 of the pressure relief valve body 18, and the valve closing spring 13 is inserted into the spring seat hole 17. By reducing the gap 12 between the leakage prevention/drain valve bodies 10 and 11 to the necessary minimum size in light of the flow rates of the pressure port 7 and return port 8, the entire switching valve 3 can be made smaller and more compact. However, this is not an essential configuration for the present invention.

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.

The valve opening device 14 for opening the drain valve body 11 may be a manual type or a hydraulic type, but in this example, it is pneumatically driven as shown in FIG. 4.

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 in 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 return port 8 from the piston 20. Also includes a drain valve opening pin 23b near the proximal end.

The drain valve opening pin 23b is formed to have a larger diameter than the pressure relief oil passage hole 15.

The pressure receiving chamber 21 is filled with compressed air, and the piston 2
0 is advanced toward the valve box 5 side against the return spring 22, first, as shown in FIG. A passage is formed from the valve chamber 6 through the pressure relief oil passage hole 15 to the return port 8, and the internal pressure of the valve chamber 6 drops rapidly.

When opening the pressure relief valve body 18, the valve opening device 14 opens the narrow pressure relief oil passage hole 1, except for the elasticity of the valve closing spring 13.
Since the internal pressure of the valve chamber 6 is merely received over the opening area of 5, the valve can be opened easily.

Around the same time that the internal pressure of the valve chamber 6 becomes a low pressure almost equal to the internal pressure of the return port 8, that is, close to atmospheric pressure, the drain valve opening pin 23b pushes the drain valve body 11 against the valve closing spring 13. It opens, allowing a large amount of hydraulic oil to flow out from the return port 8.

Since the resistance when pushing open the drain valve body 11 is only the elasticity of the valve closing spring 13, the drain valve body 11
was fully opened in an instant, as shown in Figure 7.
The drain valve opening pin 23b of the valve opening device 14 pushes and closes the leakage prevention valve body 10 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 and pressure oil is discharged 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 to 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, 1b.

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, reference numeral 27 indicates a valve opening control valve, and in FIG. 4, 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 (f).

(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.

(F) First, the pressure relief valve body is pushed open with a valve opening device against the slight pressure in the valve chamber and the valve closing spring to eliminate the pressure difference between the valve chamber and the return port, and then the large diameter drain is opened. Since the valve body is opened, the resistance to the output of the valve opening device is small, the opening speed of the pressure relief valve body and the drain valve body can be increased, and the time required for discharging the pressure oil can be shortened, and the work cycle can be shortened. Moreover, the valve opening device can be made small and low output.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional hydraulic cylinder equipped with a known locking circuit; FIG. Figures 3 to 6 show an 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, Fig. 6 is an oil flow path diagram inside the switching valve at the initial stage when pressure oil is discharged, and Fig. 7 is an oil flow path diagram inside the switching valve when pressure oil is being discharged. It is an oil flow path diagram in the switching valve from the middle to the final stage. 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, 15 ... Pressure relief oil passage hole, 16 ... Pressure relief valve chamber, 17 ... Spring seat hole,
18...Pressure relief valve body.

Claims (1)

[Claims] 1. 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 of the pressure port 7. A seat-valve type escape prevention valve body 10 that opens and closes a seat-type drain valve body 11 that opens and closes the return port 8 are arranged in series with a gap 12 in the valve chamber 6, and the drain valve body 11 is arranged in series with a gap 12 therebetween. A pressure relief oil hole 15 with a smaller diameter than the return port 8 is located along its axis.
A seat valve-shaped pressure relief valve body 18 that opens and closes the pressure relief oil passage hole 15 and a valve closing spring 13 are interposed in series between the two valve bodies 10 and 11, so that each valve body 1
0, 11, and 18 to the closed position, the flow prevention valve body 10 is made openable against the valve closing spring 13 by the supplied hydraulic pressure from the pressure oil port 7, and the pressure release device 14 is opened. Push the pin 23a from the pressure relief oil passage hole 15 to the pressure port 7 side to close the pressure relief valve body 18 between the valve closing spring 13 and the valve chamber 6.
Pressure relief valve body 1 can be pushed open against the internal pressure of
8 is pushed open, the drain valve body 11 is configured to be able to be pushed open toward the pressure port 7 side by the drain valve opening pin 23b of the valve opener 14. 14, the escape prevention valve element 10 is pushed closed via at least one of the pressure relief valve element 18 and the drain valve element 11 against the supply hydraulic pressure of the pressure port 7. Pressure oil supply/blockade/discharge switching valve. 2. In the pressure oil supply/blocking/discharge switching valve for the cylinder circuit described in claim 1, the side surface of the return port 8 of the escape prevention valve body 10 and the drain valve body 1
A pressure relief valve chamber 16 is recessed in the side surface of the pressure port 7 or one of these, and a pressure relief valve body 18 is inserted into the pressure relief valve chamber 16. 3. In the pressure oil supply/blocking/discharge switching valve for the cylinder circuit described in claim 1 or 2, the side surface of the return port 8 of the escape prevention valve body 10 and the pressure relief valve body 18 are A spring seat hole 17 is recessed in the side surface of the pressure port 7 or one of these.
A valve closing spring 13 is inserted into the valve.