JPS594163Y2 - hydraulic control device - Google Patents

Description

[Detailed description of the invention] This invention relates to a hydraulic control device that drives a load such as an actuator using a reversible low-pressure large-flow pump, a reversible high-pressure small-flow pump, a pressure control valve, etc. .

In processing machines, etc., when a low-pressure, large-flow hydraulic oil is supplied to the feed actuator for rapid feed operation, and a high-pressure, small-flow hydraulic oil is supplied to provide throttling or cutting feed, Hi-L is used. .

A hydraulic control circuit called a circuit is used, and a conventional hydraulic control circuit of this type is shown in FIG.

In FIG. 1, 1 is a low-pressure, large-flow constant-discharge pump, and 2 is a high-pressure, small-flow, constant-discharge pump.
are rotated in one direction by a common electric motor 3, and the suction sides of the pumps 1 and 2 are communicated with an oil tank 5 via a strainer 4, and the discharge sides of the pumps 1 and 2 are connected to an oil tank 5 through a strainer 4. is connected to an actuator, for example, a hydraulic cylinder 7, via a directional control valve 6, and an unload valve 8 is connected to the discharge oil path of the low-pressure large-flow pump 1 to operate the pump 1 under no load. A relief valve 9 for relieving the pump 2 is connected to each discharge side oil passage.

In such a conventional circuit, when the hydraulic cylinder 7 is moved forward or backward in rapid traverse, when the directional control valve 6 is switched to position 6a or position 6b, the oil discharged from both pumps 1 and 2 is combined and the hydraulic pressure is increased. It flows into the cylinder 7.

Furthermore, when a load such as cutting feed is applied to the hydraulic cylinder 7, the hydraulic pressure increases, so the unload valve 8 opens due to the hydraulic pressure, opening the discharge side of the low-pressure large-flow pump 1 to the tank, and leaving the pump 1 unloaded. , only the oil discharged from the high-pressure, small-flow pump 2 is supplied to the hydraulic cylinder 7.

However, in the above hydraulic control circuit, there is only one hydraulic pressure supply port to the actuator, so a directional switching valve is required to move the actuator, such as a hydraulic cylinder, forward or backward. When you let
Since the set pressures of the hydraulic oil from the pumps supplied to the inlets A and B are the same, optimum control cannot be performed, resulting in an increase in oil temperature.

This idea was made in order to eliminate the above-mentioned drawbacks of the conventional technology. Two Hl-LO circuits are constructed by incorporating an unload valve, a relief valve, and a pair of pilot-operated check valves provided in the oil passages connecting the discharge side of the low-pressure large-flow pump and both outflow inlets of the actuator. The present invention provides a hydraulic control device in which the unload valve and the relief valve are adjusted to set respective pressures for the reciprocating operation of the actuator, and to reduce the temperature rise of the hydraulic oil. It is in.

Embodiments of this invention will be described below with reference to the drawings.

FIG. 2 is a circuit diagram showing an example of a hydraulic control device according to this invention, in which 10 is a reversible low-pressure large-flow pump;
shows a reversible high-pressure small-flow pump, and these pumps 10
．． 11 are directly connected in common to an electric motor 12 which can rotate in forward and reverse directions.

Oil passages 13 and 14 are connected to both plate outlets 10a and 10b of the low-pressure large-flow pump 10, respectively.
．． 14 is connected to separate oil passages 17 and 1B that communicate with an actuator, for example, a hydraulic cylinder 15 and an oil tank 16, and the oil tank communication side of the oil passage 17.18 is connected to the forward and reverse rotation of the pump 10. Check valves 19, 20 are inserted in each of the oil passages 17.1B, and pilot operated check valves 21, 22 are inserted in the hydraulic cylinder communication side of the oil passage 17.1B.

The hydraulic pressure generated in the oil passage 18 on the suction/discharge port 10b side of the pump 10 is applied as pilot pressure to the pilot operated check valve 21, and the pilot operated check valve 22 is configured to apply the hydraulic pressure generated in the oil passage 18 on the suction/discharge port 10b side of the pump 10 as a pilot pressure. The hydraulic pressure generated in the a-side oil passage 17 of the suction/discharge port 10 is applied as pilot pressure.

Further, both plate discharge ports 11a, l of the high pressure small flow rate pump 11
Oil passages 23 and 24 are connected to each of the oil passages 23 and 24, and one oil passage 23 is connected to an oil passage 25 connected in parallel to the oil passage 17 including the check valve 19 and the pilot-operated check valve 21.
The other oil passage 24 is connected to the check valve 20,
It is connected to an oil passage 26 that is connected in parallel to oil passage 1B that includes a pilot-operated check valve 22, and each oil passage 2
Check valves 27 and 28 are respectively inserted on the oil tank communication side of the pumps 5 and 26 to facilitate suction of hydraulic oil by forward and reverse rotation of the pump 11.

Reference numerals 29 and 30 are unload valves for pump no-load, which are connected to both class outlet side oil passages 17 and 1B of the low-pressure large-flow pump 10, respectively. The hydraulic pressure generated in the oil passages 25 and 26 of the pump 11 is applied as pilot pressure.

Reference numerals 31 and 32 are relief valves connected to both class outlet oil passages 25 and 26 of the high-pressure and small-flow pump 11, respectively, so that the circuit pressure on the suction and discharge port 11a side or 11b side of the pump 11 is applied to the relief valve. When the set value is reached, it functions to release some or all of the hydraulic oil in that circuit to the return side (oil tank 16).

In addition, the pump 10.11, the pilot operated check valve 21, the unload valve 29, and the relief valve 31 are connected to one Hl-Lo.
The circuit is connected to the pump 10.11 and the pilot operated check valve 22.
, the unload valve 30 and the relief valve 32 are connected to the other Hi-L
o circuits are formed respectively.

Next, the operation of this device constructed as described above will be explained.

In FIG. 2, when the low-pressure large-flow pump 10 and the high-pressure small-flow pump 11 (hereinafter simply referred to as pump 10 and pump 11) are driven to rotate in the normal direction as the electric motor 12 rotates in the normal direction, the check valve 19.27 is held closed by the pump discharge pressure, and the check valve 20.2B is held open by the pump suction pressure.

When the check valve 20 is opened, the hydraulic oil in the oil tank 16 is sucked by the pump 10 through the check valve 20 and the oil passages 1B and 14 as shown by the solid line arrow, and then through the suction and discharge port 10 of the pump 10.
The oil discharged from a flows into the head side of the hydraulic cylinder 15 as shown by the solid line arrow through the path of oil passage 13 - oil passage 17 - pilot operated check valve 21, and moves the piston 15 a forward in the direction of arrow X. make it move.

At the same time, check valve 2B, oil passages 26, 2
The hydraulic oil sucked by the pump 11 through the pump 11 is discharged from the suction/discharge port 11a, and further passes through the oil passage 23.25, mixed with the oil discharged from the pump 10, and flows into the hydraulic cylinder 15.
is supplied to the head side of the

On the other hand, as the oil discharged from the pump 10 is supplied to the hydraulic cylinder 15 through the pilot operated check valve 21, the pressure in that circuit increases, and this is added to the pilot operated check valve 22 as pilot pressure, causing the pilot operated check valve 22 to Open the stop valve 22.

For this reason, the return oil in the rod side of the hydraulic cylinder 15 flows through the pilot-operated check valve 22, the oil path 1B, and
14 to the suction side of the pump 10, and also to the suction side of the high-pressure, small-flow pump 11 through oil passages 26, 24.

This facilitates the suction properties of the pump 10.11.

That is, since a predetermined flow energy is given to the hydraulic oil on the rod side pushed out by the forward movement of the hydraulic cylinder 15, the returning hydraulic oil is transferred to the suction side of the pumps 10 and 11. This allows the pumps 10 and 11 to suck up oil directly from the oil tank 16, which improves the suction performance of the pumps 10 and 11 compared to the case where the oil is sucked up directly from the oil tank 16, and the load on the motor 12 can be reduced accordingly.

In addition, such an action is caused by the pumps 10 and 11 being rotated in the opposite direction, and the return oil on the head side of the hydraulic cylinder 15 being pumped 1.
The same applies to the case of being sucked into 0 and 11.

When the rapid feed operation of the hydraulic cylinder 15 due to the above-mentioned low-pressure, large-flow oil supply ends and enters a heavy load stage such as cutting feed, and a load is applied to the forward movement of the hydraulic cylinder 15, the pump 1
The oil pressure of the discharge side circuit increases to 0.11, thereby opening the unload valve 29.

Therefore, the oil discharged as the pump 10 rotates is discharged into the oil tank through the unload valve 29, and the pump 10 is left unloaded.

Accordingly, only high-pressure, small-flow discharge oil from the pump 11 is supplied to the head side of the hydraulic cylinder 15, and the hydraulic cylinder 15 is operated for cutting and feeding.

Further, when the hydraulic cylinder 15 reaches the forward end, a reverse rotation command is given to the electric motor 12, and as a result, the electric motor 12 is given a reverse rotation command.
2 is reversely rotated through the stop process, the pump 10.11
are rotated in the same direction, and accordingly, the check valve 20.2
8 is closed and check valve 19.27 is opened.

Then, it is sucked by the reverse rotation drive of pumps 10 and 11,
The discharged low-pressure hydraulic oil is mixed and flows into the rod side of the hydraulic cylinder 15 through the respective oil passages 14.18 and 24.26 as indicated by the dashed arrows, resulting in low pressure, large flow rate,
That is, the hydraulic cylinder 15 is moved backward by rapid forwarding.

At this time, the hydraulic pressure generated in the circuit of the oil passage 1B opens the pilot-operated check valve 21, and the return oil flowing out from the head side of the hydraulic cylinder 15 is directed to the pilot-operated check valve 21. The oil is supplied to the suction side of the pump 10 through oil passages 17 and 13, and a portion of the return oil is supplied to the oil passages 25 and 23.
It is supplied to the suction side of the pump 11 through.

When the hydraulic cylinder 15 reaches the backward end, the electric motor 1
2 stops and waits for the next hydraulic cylinder operation.

Note that when the pump 11 is activated, the circuit pressure is
Or when the set pressure of 32 is reached, the relief valve 31 or 3
2 opens to maintain the pressure in the circuit at the set point.

In addition, when setting the pressure of the hydraulic oil supplied to the head side and rod side of the hydraulic cylinder 15, the unload valve 29 and the linenof valve 31 provided in the head side circuit. Unload valve 30 and relief valve 3 provided in the rod side circuit
All you have to do is adjust the pressure of the springs provided in each of 2.

In other words, the hydraulic cylinder 1 can be adjusted by simply adjusting the spring pressure using the adjustment parts of one or both of the unload valve and the relief valve.
The pressure of the hydraulic oil on the head side and the rod side of 5 can be easily set individually to different values.

As described above, the hydraulic control device of this invention has a low-pressure large-flow pump and a high-pressure small-flow pump that can rotate in forward and reverse directions.
By combining a pair of unload valves and a relief valve, and a pair of pilot-operated check valves, two Hi
-Lo circuit, so each Hi-L.

By adjusting the operating pressure of one or both of the unload valve and relief valve in the circuit, each pressure setting for the reciprocating process operation of the actuator can be easily set individually, and the optimum set pressure according to the load can be obtained. In addition, since the direction of the hydraulic oil relative to the actuator can be changed by configuring the pump motor in a forward/reverse circuit, a directional control valve is not required, and the structure of the hydraulic control device is simplified accordingly.

Furthermore, the suction of the actuator and the low-pressure large-flow pump,
A pilot-operated check valve is built into the oil path between the discharge sides, allowing return oil from the actuator to be introduced into the suction side of the pump, which improves the suction performance of the pump compared to when drawing hydraulic oil directly from the oil tank. This has the effect of reducing the load on the pump drive source.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a conventional hydraulic control device, and FIG. 2 is a circuit diagram showing an example of a hydraulic control device according to this invention. 10...Low pressure large flow pump, 10 a, 10
b... Suction/exhaust port, 11... High pressure small flow pump, 11 a, 11 b... Suction/exhaust port, 1
2...Electric motor, 13.13.17.1B, 2
3.24゜25, 26... oil passage, 15...
... Hydraulic cylinder, 16... Oil tank, 19.
20.27.2B...Check valve, 21.22...
...Pilot operated check valve, 29.30...
・Unload valve, 31, 32...Relief valve.

Claims (1)

[Scope of utility model registration request] A reversible low-pressure large-flow pump 10 and a high-pressure small-flow pump 11 driven by an electric motor capable of forward and reverse rotation, and respective intake and discharge ports 10 a, 10 b, 11 of the low-pressure large-flow pump 10 and high-pressure small-flow pump 11. Check valves 19, 20, 27.2B provided in the oil passages communicating between a, 11b and the oil tank 16, both the binocular outlets 10a and 10b of the low-pressure large-flow pump 10, and the actuator 15 are operated. The pumps are provided in the oil passages connecting the oil outflow ports separately, and are opened by the discharge pressure of the low-pressure large-flow pump 10 on opposite sides of the oil passages in which they are provided, and the return oil of the actuator 15 is opened. A pair of pilot-operated check valves 21, 22 leading to the suction side of the low-pressure, large-flow pump 10, binocular outlets 10a, 10b of the low-pressure, large-flow pump 10, and the pilot-operated check valves 21, 22.
unload valves 29 and 30 connected separately to the oil passages connecting the connection point with the oil tank and the high-pressure small-flow pump 11;
A hydraulic control device comprising relief valves 31 and 32 respectively connected to oil passages connecting the oil tank and a connection point between the eye outlets 11 a and 11 b of the actuator 15 and both hydraulic oil inlets of the actuator 15 .