JPH0465248B2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention is suitable for use as a safety device for press-related main machinery, etc., and is a hydraulic system that can automatically remove fluid from the main line when stopped. Regarding circuits.

<Prior art> In press work, etc., when the main machine stops due to work stoppage or power outage, high-pressure fluid is sealed in the fluid circuit, so when the power is turned on next time, the sealed high-pressure fluid starts the main machine. It is extremely dangerous to operate suddenly. Therefore, it is necessary for safety to release the fluid pressure in the fluid circuit using a bleed valve when the main engine is stopped.

Conventionally, as a fluid circuit using such a bleed valve, there is a hydraulic circuit as shown in FIG. 4 using a single solenoid spring offset type 4-port solenoid valve 81 as shown in FIG. . This solenoid valve 81 is connected via a line 86 to the downstream side of a check valve 83 provided in a main line 85 connected to the discharge side of a variable displacement pump 82. Further, a tank 89 is connected to the electromagnetic valve 81 via a line 87.

The bleed valve 81 in the fluid circuit is
When the press is to be operated, the solenoid S ₈₁ is energized, the symbol position is switched to the V ₆ side, the space between the main line 85 and the tank 89 is closed, and the pressure oil from the pump 82 is supplied to the main machine. Also, when stopping the main engine, turn off solenoid S ₈₁ , switch the symbol position to the V ₅ side, and turn off the main line 8.
The pressure oil sealed in 5 is discharged to tank 89.

<Problems to be Solved by the Invention> However, in the above-mentioned fluid circuit, when the press-related main machine is operating, continuous energization is required in order to set the symbol position of the bleed valve 81 to the V ₆ side, and the running There is a problem that costs increase. Also, this bleed valve 8
Since the valve 1 is a solenoid valve, an electric circuit is required to operate it, and there is a problem in that the configuration of the fluid circuit becomes complicated.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a hydraulic circuit that can automatically and reliably remove fluid from a main line using fluid pressure without requiring an electric circuit.

<Means for Solving the Problems> In order to achieve the above object, the hydraulic circuit of the present invention includes a hydraulic pump 51 and a hydraulic pump 51, as illustrated in FIGS. 1 and 3. The hydraulic circuit includes a check valve 56 interposed in a main line 57 and a pilot bleed valve 1 connected to the main line 57, the pilot bleed valve 1 communicating with the inlet 16 and the outlet 24. The valve body 2 has a valve chamber 7 that is slidably fitted into the valve chamber 7 to form a pilot chamber 31 that communicates with a pilot port 33 on the back side. and exit 2
4, and a spring 26 compressed between the front surface of the poppet 3 and the wall surface of the valve body 2, and the inlet 16 is connected to the check valve 5 in the main line 57.
6, the outlet 24 is connected to the tank 63, and the pilot port 33 is connected to the upstream side of the check valve 56 in the main line 57, so that when the hydraulic pump 51 is stopped, the outlet 24 is connected to the tank 63. , the liquid downstream of the check valve 56 in the main line 57 is transferred to the tank 6.
It is characterized by opening within 3 hours.

<Function> When the hydraulic pump 51 is driven, the check valve 5 in the main line 57 of the hydraulic pump 51 is activated.
Fluid is supplied to the pilot chamber 31 of the pilot bleed valve 1 connected to the upstream side of the valve body 2, and the poppet 3, which is slidably fitted into the valve chamber 7 of the valve body 2, is moved by the spring pressure of the spring 26. Victory Benshiro 7
It moves inside and comes into close contact with the valve seat 17. In this way, the space between the inlet 16 and the outlet 24 of the valve chamber 7 is automatically closed by the fluid pressure, and the tank 6 is opened from the downstream side of the check valve 56 in the main line 57.
Fluid flow to 3 is stopped.

On the other hand, when the hydraulic pump 51 is stopped and the pressure in the pilot chamber 31 of the pilot bleed valve 1 is reduced, the poppet 3 is moved by the spring pressure of the spring 26 and separated from the valve seat 17. Therefore, the space between the inlet 16 and the outlet 24 of the valve chamber 7 is opened. In this way, fluid flows from the main line 57 through the pilot bleed valve 1 to the tank 63, and pressure is automatically relieved.

In this way, the pilot bleed valve 1
In the hydraulic circuit using the hydraulic pump 51, the pressure of the fluid supplied to the pilot chamber 31 of the pilot bleed valve 1 is automatically used to control the fluid downstream of the check valve 56 in the main line 57. Discharge/stop to tank 63 is controlled.

<Examples> The present invention will be described in detail below with reference to illustrated examples.

FIG. 1 is a sectional view of a pilot bleed valve used in the hydraulic circuit of the present invention as shown in FIG. In Fig. 1, 1 is the valve body 2
and poppet 3 and first cap 5 and second cap 6
It is a pilot bleed valve consisting of. The valve body 2 has a cylindrical valve chamber 7 inside,
The poppet 3 is slidably fitted into the valve chamber 7. An annular groove 14 is formed on the substantially central wall surface of the valve chamber 7.
An inlet port 16 is communicated with the annular groove 14. An annular valve seat 17 is provided along the wall surface of the valve chamber 7 at a step 2a where the wall 14a of the annular groove 14 on the first cap 5 side and the valve chamber 7 intersect.

The first cap 5 has a stepped cylindrical appearance, and a substantially U-shaped groove 18 is provided in the stepped portion of its outer peripheral surface, and a screw 19 is provided in the outer peripheral surface of the end portion 5a. An O-ring 21 is fitted into the groove 18 of the first cap 5, and a screw 19 is inserted into the valve body 2.
By screwing and tightening the screw 12 provided on the end 9 of the valve body 2, an O-ring 21 is enclosed in the groove 18 between the groove 18 and the end surface 9a of the valve body 2, and the valve chamber 7 is sealed. . Furthermore, the first cap 5
A stepped hole 22 is provided in the center of the hole 22 and communicates with an outlet port 24 .

The end 3a of the poppet 3 that comes into contact with the valve seat 17
has a conical shape, and when it moves inside the valve chamber 7 to the left in the figure, it comes into close contact with the valve seat 17 of the valve body 2 and stops the flow of fluid from the inlet port 16 to the outlet port 24. , poppet 3 is valve seat 17
The center of the valve chamber 7 and the center of the poppet 3 are made to coincide when the valve chamber 7 and the poppet 3 are brought into close contact with each other. In this manner, the center of the valve chamber 7 and the center of the poppet 3 are aligned due to the action of the valve seat 17, so that the poppet 3 does not come into close contact with the circumferential wall surface of the valve chamber 7 in an uneven manner. Therefore, when the poppet 3 leaves the valve seat 17, no hydrolock phenomenon occurs. A hole 25 having an entrance on the end 3a side is provided in the center of the poppet 3.
and the stepped portion 2 of the stepped hole 22 of the first cap 5.
A spring 26 is compressed between the poppet 2a and the poppet 3 to urge the poppet 3 to the right in the figure. Therefore, the poppet 3 is normally in an open state (ie, a normally open valve).

The second cap 6 has a stepped cylindrical appearance similar to the first cap 5, and has a substantially U-shaped groove 27 in the stepped portion of its outer circumferential surface, and has a screw thread on the outer circumferential surface of the end 6a. 29 are provided. By fitting the O-ring 30 into the groove 27 and tightening the screw 29 with the screw 13 provided at the end 10 of the valve body 2, the groove 27 and the valve body 2 are tightened.
An O-ring 30 is enclosed in the groove 27 with the end face 10a of the valve chamber 7, thereby sealing the valve chamber 7. A pilot chamber 31 is formed by the valve body 2, poppet 3, and second cap 6. Further, a hole 32 is provided in the center of the second cap 2, and this hole 32 communicates with a pilot port 33.

The pilot bleed valve 1 having the above configuration has the fluid pressure of the fluid supplied from the pilot port 33 to the pilot chamber 31 between the poppet 3 and the first valve.
When the spring pressure is lower than the spring pressure of the spring 26 compressed between the poppet 3 and the cap 5, the poppet 3 is biased toward the right side in the figure by the spring 26, and the flow path between the inlet port 16 and the outlet port 24 is opened. and inlet port 1
The fluid flowing in from 6 is discharged from outlet port 24. On the other hand, when the fluid pressure acting on the back surface 3b of the poppet 3 due to the fluid supplied to the pilot chamber 31 becomes higher than the spring pressure of the spring 26, the poppet 3 overcomes the spring pressure and moves inside the valve chamber 7. It moves to the left in the figure to bring the end 3a into close contact with the valve seat 17, closing the space between the inlet port 16 and the outlet port 24, and stopping the flow of fluid from the port 16 to the outlet port 24. Therefore, opening and closing between the inlet port 16 and the outlet port 24 can be automatically controlled by the pilot pressure applied to the poppet 3. FIG. 2 shows the hydraulic symbol of this pilot bleed valve 1.

FIG. 3 shows a fluid circuit when the hydraulic circuit of the present invention is used as a driving hydraulic circuit for a press-related main machine.

In FIG. 3, reference numeral 51 denotes a variable displacement pump 52 which has a discharge amount control section 55 which is driven by a driving electric motor M and is composed of, for example, a swash plate control cylinder.
2 switches the direction of the discharge flow path of the pump 51
The position switching valve 53 is operated by pressure oil supplied from the pump 51 via the two-position switching valve 52.
The hydraulic clutch 1, which connects and disconnects, is the above-mentioned pilot bleed valve.

The discharge side of the variable displacement pump 51 has a check valve 56 that allows the flow from the pump 51 to flow freely.
The secondary side of the two-position switching valve 52 is connected to the hydraulic clutch 5 via a line 59 via a main line 57 having a
Connect to 3. Further, one of the two-position switching valves 52 is
The next side is connected via line 60 to the inlet port 16 of the pilot bleed valve 1, while the outlet port 24 is connected via line 61 to the tank 63. Further, the pilot port 33 is connected to the main line 57 via a pilot line 64.
The discharge amount control section 55 of the pump 51 is connected to the pilot line 64 via a pilot line 65. The accumulator 67 is connected to the line 6 downstream of the check valve 56 of the main line 57.
Connect via 8.

The fluid circuit operates as follows.

The discharge amount control unit 55 rotates the drive electric motor M.
When the variable displacement pump 51 with 3 to spring 26
The poppet 3 is moved to the left side in the figure by overcoming the spring pressure, and the end 3a of the poppet 3 is brought into close contact with the valve seat 17, that is, the pilot bleed valve 1 in FIG.
The symbol position switches to the V ₄ side and line 60
will be closed. As a result, the pressure oil in the main line 57 is supplied to the two-position switching valve 52 via the check valve 56. Here, the two-position switching valve 5
When the solenoid S ₅₂ of 2 is energized, the 2-position switching valve 5
2 is switched to the symbol position V ₂ side, and immediately after energization, pressure oil from the pump 51 and pressure oil from the accumulator 67 are supplied to the hydraulic clutch 53, which connects and starts the press. Drives the main engine.

In this way, while the press main machine is being driven, the pilot bleed valve 1 can be automatically closed only by fluid pressure without requiring any other power. This fluid circuit therefore saves energy. Furthermore, when the two-position switching valve 52 is switched, the accumulator 6
By discharging the pressure oil of 7 to the hydraulic clutch 53, the capacity of the pump 51 is reduced.

Thereafter, the two-position switching valve 52 is moved to the symbol position V ₁
When the hydraulic clutch 53 is switched to the side to stop the supply of pressure oil to the hydraulic clutch 53 and release the hydraulic clutch 53, the pressure oil from the pump 51 is filled into the accumulator 67, and after filling, the main line 57 and pilot lines 64, 65 are The discharge amount control unit 55 of the pump 51 is controlled through the pump 51 to reduce its discharge amount. As a result, the pump 51 is controlled to a minute flow rate necessary to maintain the fluid pressure at the spring pressure of the spring 55a of the discharge amount control section 55.

In this way, in the driving state of the pump 51 described above, the pressurized oil discharged from the pump 51 controlled by the discharge amount control section 55 is kept constant at the spring pressure of the discharge amount control section 55, and the pressing operation is performed. It is.

Next, when the solenoid S ₅₂ of the two-position switching valve 52 is turned off due to a press stop or power outage, etc.
The symbol position of the two-position switching valve 52 is switched to the V ₁ side, and the pressure oil in the line 59 is discharged to the tank 69. Furthermore, when the power supplied to the driving electric motor M is turned off, the pump 51 stops, and the oil pressure in the main line 57 and pilot line 64 upstream of the check valve 56 decreases, and the pilot bleed valve 1, the symbol position of the pilot bleed valve 1 switches to the _V3 side, and the accumulator 67, the two-position switching valve 52 at the symbol position _V1 side, the check valve 56, the symbol position The pressure oil sealed in the accumulator 67 and the pipe line between the pilot bleed valves 1 on the _V4 side is discharged to the tank 63 via the tank line 61, and the circuit becomes low pressure.

Therefore, even if the power is turned on next time and the solenoid S 52 of the two-position switching valve ₅₂ is energized and the symbol position is switched to the V ₂ side, the pressure oil in the accumulator 67 and the pipe line is line 68,5
7, 59 to the hydraulic clutch 53 to prevent the press from operating.

As described above, according to the hydraulic circuit of this embodiment, the pilot bleed valve 1 is controlled by the fluid pressure on the upstream side of the check valve 56 in the main line 57 to open/stop the downstream fluid to the tank. Since it can be controlled, the fluid in the main line 57 can be automatically drained with a simple fluid circuit that does not require an electric circuit and at low running costs.

In addition, since the pilot bleed valve 1 is of a poppet type with a conical tip, this conical surface is pressed against the valve seat, and the center of the valve chamber and the center of the poppet coincide, so that the poppet touches the peripheral wall of the valve chamber. Since the valve body is separated from the valve body, unlike the spool type, the valve body is not pressed against the surrounding wall surface.
No hydrolock phenomenon occurs. Therefore,
The fluid in the main line 57 can be reliably drained.

<Effects of the Invention> As is clear from the above, the hydraulic circuit of the present invention includes a valve body having a valve chamber that communicates with an inlet and an outlet, and a valve body that is slidably fitted into the valve chamber and is in contact with a valve seat. A poppet that opens and closes between the inlet and the outlet by separating them and forms a pilot chamber communicating with the pilot port on the back side, and a spring compressed between the front face of the poppet and the wall of the valve body. The inlet of the pilot bleed valve is connected to the upstream side of a check valve installed in the main line of the hydraulic pump, while the outlet is connected to the tank, and the pilot port is connected to the check valve installed in the main line of the hydraulic pump. Since it is connected to the upstream side, the fluid pressure of the fluid discharged from the hydraulic pump and supplied to the pilot chamber through the pilot port of the pilot bleed valve creates a connection between the main line and the tank. Opening and closing can be controlled automatically.

Therefore, according to the hydraulic circuit of the present invention, the fluid in the main line can be automatically drained using fluid pressure without requiring an electric circuit to operate the bleed valve, thereby reducing running costs. I can do it.

Further, when the poppet of the pilot bleed valve is closed, the poppet and the valve seat properly abut to close the space between the inlet and the outlet. Therefore, the hydraulic circuit using the pilot bleed valve can operate accurately as a safety device to keep the fluid circuit safe at all times.

[Brief explanation of the drawing]

Fig. 1 is a longitudinal sectional view of a pilot bleed valve used in the hydraulic circuit of the present invention, and Fig.
Fig. 3 is a circuit diagram using the hydraulic circuit of this invention as a safety device, Fig. 4 is a main part circuit diagram using a conventional bleed valve, and Fig. 5 is a circuit diagram using the hydraulic circuit of the present invention as a safety device.
The figure is a sectional view of essential parts of the conventional bleed valve. 2... Valve body, 3... Poppet, 5... First cap, 6... Second cap, 7... Valve chamber, 17... Valve seat, 26... Spring, 16... Inlet port, 24... Outlet port, 31... Pilot chamber, 33...Pilot port.

Claims (1)

[Scope of Claims] 1. A hydraulic pump 51, a check valve 56 interposed in a main line 57 of the hydraulic pump 51,
The hydraulic circuit includes a pilot bleed valve 1 connected to the main line 57, the pilot bleed valve 1 comprising: a valve body 2 having a valve chamber 7 communicating with an inlet 16 and an outlet 24; A pilot chamber 31 is slidably fitted into the chamber 7 and communicates with a pilot port 33 on the back side.
while forming the inlet 1 in contact with and separating from the valve seat 17.
6 and the outlet 24; a spring 26 compressed between the front surface of the poppet 3 and the wall surface of the valve body 2; While connected to the downstream side of the valve 56,
The outlet 24 is connected to the tank 63, and the pilot port 33 is connected to the main line 57.
The hydraulic pump is connected to the upstream side of the check valve 56 in the main line 57 and releases the liquid downstream of the check valve 56 in the main line 57 into the tank 63 when the hydraulic pump 51 is stopped. circuit.