JPS59725B2 - hydraulic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a hydraulic control device for a hydraulic actuator using a variable displacement pump, and particularly to a hydraulic control device designed to improve control response.

Conventionally, as this type of hydraulic control device, one shown in FIG. 1, for example, has been used.

In FIG. 1, 1 is a variable discharge pump using a vane pump or the like that varies the discharge amount by adjusting the eccentricity of the ring using a control actuator 1a, and 2 is a variable discharge pump that uses a vane pump or the like to vary the discharge amount by adjusting the eccentricity of the ring using a control actuator 1a. A flow rate control valve to be controlled, 4 is a directional switching valve that switches the oil pressure supplied to the cylinder 3 to perform reciprocating operation, and 5 is a flow rate control valve based on the differential pressure ΔP□ generated between the primary side and the secondary side of the flow rate control valve 4. A flow rate control pilot spool valve 6 controls the discharge amount of the variable discharge amount pump 1 so that the flow rate supplied to the cylinder 3 becomes the set flow rate, and 6 is based on the pilot pressure taken out from the primary side of the flow rate control valve 2. a pressure control pilot spool valve that controls the discharge pressure of the variable discharge amount pump 1 to maintain the cylinder supply pressure at a set pressure based on the differential pressure ΔP2 generated at the throttle 8 when the remote control relief valve 1 is activated; is a safety valve that operates when a high pressure that cannot be controlled by the pressure control spool valve 6, for example, a peak pressure when the cylinder is stopped, discharges the output of the variable discharge pump 1 to the tank 10.
pressure compensation valve).

Here, the pilot pressure of the remote control relief valve T is connected to the vent circuit of the safety valve 9.
This is to perform the sequential operation of operating the safety valve 9 after the valve 1 blows, and prevents the generation of high pressure due to a delay in the response of pressure control.

Further, the throttle 11 is a pilot spool valve 5 for flow rate control.
Alternatively, when the pressure control pilot spool valve 6 is switched to the right side and the control actuator 1a of the variable discharge amount pump 1 is connected to the tank, it is provided to prevent oil from returning to the tank due to pilot pressure. It will be done.

According to such a hydraulic control device, the operating speed of the cylinder 3 is determined by the flow rate setting by the throttle of the flow control valve 2, and this set flow rate, that is, the differential pressure ΔPl generated in the flow control valve 2
The flow rate control valve 5 switches to keep the flow rate constant and supplies control oil pressure to the control actuator 1a of the variable discharge rate pump 1 to vary the discharge rate.On the other hand, the pressure control that determines the operating force of the cylinder 3 When the supply pressure exceeds the set pressure set in the remote control relief valve 1 when the cylinder 3 is throttled or the cylinder 3 is stopped, the remote control relief valve 1 causes pilot pressure to flow into the tank 10 and into the throttle 8. A differential pressure ΔP2 is generated, and this differential pressure ΔP2
Pilot spool valve 6 for pressure control to keep the pressure constant.
is switched to supply control hydraulic pressure to the control actuator 1a of the variable discharge amount pump 1 to vary the discharge amount.

However, the above-mentioned hydraulic control device has various problems regarding the responsiveness of flow rate control and pressure control.

First, the problem with flow rate control is that because the throttle 11 is provided in the circuit that supplies control oil pressure from the pilot spool valve 5 for flow rate control to the control actuator 1a of the variable discharge amount pump 1, the flow of oil to the control actuator 1a is limited. This is bad and makes the responsiveness worse.

Furthermore, the variable discharge amount pump 1 can be varied within the range from zero discharge amount to the maximum discharge amount, but even if the throttle of the flow control valve 2 is opened from the state of zero discharge amount, the flow rate to the cylinder 3 remains the same as the discharge amount. The flow rate gradually increases from the zero state, and there is a large delay in increasing the flow rate when the flow rate control valve 2 is opened.

On the other hand, a problem with pressure control is that the control of the pressure control pylon spool valve 6 by the remote control relief valve 1 and throttle 8 is not based on the load pressure of the cylinder 3 but on the pump discharge pressure. The relief setting pressure must be set high, and the higher the relief setting pressure, the cut-off characteristic of the variable discharge amount pump 1 (characteristic that makes the discharge amount zero and makes the discharge pressure the circuit setting pressure).
becomes worse, and steep cant-off characteristics cannot be obtained.

In other words, when the cylinder end is reached, the pressure in each part becomes as shown in Fig. 2, and when the cylinder end is reached, the pump discharge pressure Pa and the load pressure (cylinder pressure) Pb, which is lower by JP than the pump discharge pressure Pa, are increased. At the same time, JPL also decreases, and Pc becomes smaller than the circuit setting pressure Pc.
- When the pump discharge pressure Pa reaches the relief setting pressure PS set as JP2), the remote control valve 7
blows and generates a differential pressure ΔP2 in the throttle 8, AP2-Pc-
At Ps, the pressure control pilot spool valve 6 is switched to the right side to throttle the discharge amount of the variable discharge amount pump 1, and the load pressure pb is maintained at the circuit setting pressure Pc with the discharge amount being zero.

The way to determine the IJ IJ-7 set pressure Ps to obtain the circuit set pressure Pc based on this cant-off characteristic is as follows: Ps=Pa
-ΔP2, for example, when the circuit setting pressure Pc = 150, '4/c
rlt, ΔP 2 = 5 Ky / crri, ΔP
If i = 10 Kl/crA, pump discharge pressure Pa = Pc + ΔP 1 = 160Ki.

Therefore, the relief setting pressure Ps is Ps=160-5=
It is given at 155Kg/cm.

On the other hand, when the load pressure pb is directly applied to the remote control relief valve T, the relief setting pressure Ps is Ps=Pb-ΔP2=1505=145KI! It will be A4.

Therefore, in the conventional circuit, the pressure control is delayed as the IJ I7-F set pressure Ps is higher, and a steep cant-off characteristic cannot be obtained.

On the other hand, as is clear from Fig. 2, when the cylinder end is reached, ΔP1 becomes smaller at the same time as the pressures of Pa and pb increase.
The flow rate control pilot spool valve 5 increases the discharge amount of the variable discharge amount pump 1 and rises toward the circuit set pressure Pc, and when the relief set pressure Ps or more is generated and a specified ΔP2 occurs, the pressure control pilot spool valve is closed. 6 is activated, and at this time, the discharge amount of the variable discharge amount pump 1 is conversely throttled.

That is, as the discharge amount is increased due to the decrease in ΔP1 in the process leading to cant-off, there is a delay in narrowing down the discharge amount by pressure control, and the cut-off characteristic deteriorates.

Furthermore, in the conventional device, an interblock 12 including a pilot stool valve 5 for flow rate control, a relief valve 1 for remote control, and a pilot spool valve 6 for pressure control is assembled into one unit and attached to the variable discharge amount pump 1 side. It has been assembled in advance, and there are multiple pilot piping lines shown in broken lines between it and other flow control valves 2 and safety valves 9.
The control of flow rate and pressure by each valve of block 12 is greatly influenced by the shape and dimensions of the pilot pipe, so
Because it is difficult to obtain a pre-scheduled pilot pressure, vibrations are likely to occur and the overall circuit lacks stability.To solve this problem, the design of the manifold block that mounts the hydraulic control device is complicated. There was a problem.

The present invention was made in view of the above problems, and an object of the present invention is to provide a hydraulic control device that improves control responsiveness in flow rate control and pressure control, and improves the stability of the entire circuit. do.

Hereinafter, the present invention will be explained based on the drawings.

FIG. 3 is a hydraulic circuit diagram showing an embodiment of the present invention.

First, to explain the configuration and operation, the variable discharge amount pump 13 used in the present invention can control its discharge amount to a predetermined discharge amount,
For example, it can be varied within a range of 10 liters or more,
``Even if the supply flow rate is reduced to 10 liters or less, the minimum discharge amount is kept at 10 liters so that it does not become zero discharge amount.

As a specific example of such a variable discharge amount pump 13, for example, if we take a vane pump as an example, even if the spool valve 18 switches the actuator 13a for controlling the discharge amount to the right side and communicates with the tank 10 to exhaust pressure. , control actuator 1
The control actuator 13a is controlled so that the piston 3a stops before returning to the zero discharge amount position (zero eccentricity position).
A stopper member is provided inside the cylinder.

That is, the variable discharge rate pump 13 operates as a fixed discharge rate pump when the flow rate supplied to the cylinder is 101 Jtorr or less, and when the flow rate exceeds 10 liters, it operates as a variable discharge rate pump by the operation of the control actuator 13a. have

Of course, such a variable discharge amount pump is not limited to a vane pump, but may be a piston pump, a gerotor pump, or the like having the same function.

Next, a 6-port flow control valve 14 having a switching valve structure is provided in the main conduit of the output line of the variable discharge amount pump, and a built-in variable throttle 15 sets the flow rate supplied to the cylinder load.

Of course, as shown in the conventional example of FIG. 1, a flow control valve without a switching structure may be used, or another switching structure, for example, a 4-port one, may be used.

The advantage of this switching structure is that if the throttle 15 is inserted directly into the main pipe, the flow rate is determined by gradually opening the throttle 15, whereas with the switching structure, the opening degree is determined in advance by the throttle 15, and the flow rate is determined by opening the throttle 15 in advance. By switching, the specified flow rate can be obtained immediately, and the response at the rise is improved.

A sequence valve 16 is provided in the main pipeline on the secondary side of the flow rate control valve 14, and opens the flow passage to the secondary side when the pressure on the primary side reaches the set operating pressure. For example, when starting the hydraulic actuator, the flow path is closed until the primary pressure of the sequence valve 16 rises to the set pressure, and the speed of oil flowing into the control actuator 13a is increased. We are trying to improve responsiveness at startup.

Such improvement in responsiveness also works in the same manner when the throttle 15 of the flow control valve 14 is opened to increase speed during low-load operation.

On the other hand, the flow rate control pilot spool valve 17 takes out one of its pilot pressures from the primary side of the flow rate control valve 140, and when the differential pressure ΔP□ is smaller than a predetermined value, the flow control pilot spool valve 17 takes out one side of the pilot pressure from the primary side of the flow rate control valve 140, and when the differential pressure ΔP□ is smaller than a predetermined value, the variable discharge amount pump 13 control actuator 13a, and when the differential pressure ΔP1 approaches a predetermined value, it switches to the right side for the first time and controls the discharge amount (increase amount) by interposing a throttle in the line connected to the control actuator 13a. In addition, the pilot pressure on the spring setting side is taken out from the secondary side of the variable throttle 15 when the flow control valve 15 is switched to the right side.

Further, the pilot pipe line for the pilot spool valve 11 for flow rate control is not provided with a restriction, and the control actuator 13
Since the throttle 17a is provided on the switching side (right side) that connects a to the tank, the control response when increasing the discharge amount by the control actuator 13a of the variable discharge amount pump 13 is fast.

In addition, the pressure control pilot spool valve 18 transfers the pilot pressure that was conventionally taken out from the primary side of the flow path control valve 14 to the main pipe to the cylinder load, which is the secondary side of the sequence valve 16. It is taken directly from.

That is, the pilot pressure taken out from the secondary side of the sequence valve 16 is supplied to one side of the spool valve 18, the pilot pressure on the spring setting side is taken out through the throttle 19, and the remote control relief valve 20 is connected to this pilot line. It shall be established.

By supplying pilot pressure to the pressure control pilot spool valve 1B in this manner, pressure control can be performed based on the supply pressure of the cylinder load without being affected by the differential pressure ΔP1 generated in the flow rate control valve 14, and variable discharge The cut-off characteristic of the volume pump 13 is such that the discharge rate is immediately reduced upon reaching the set pressure, thereby obtaining a sharp cut-off characteristic.

In addition, similar to the pilot stool valve 17 for flow rate control,
Only when the differential pressure ΔP2 approaches a predetermined value is a throttle provided in the valve interposed in the line connected to the control actuator 13a, thereby increasing the pressure response.

Further, a throttle 18a is provided on the right side of the pressure control pylon spool valve 18, which eliminates the need for a throttle in the pilot line of the control actuator 13a and improves the pump response.

Furthermore, a pressure valve 21 for cutting the peak pressure that occurs when the cylinder stops operating is also provided so as to bypass the main pipeline on the secondary side of the sequence valve 16 to the tank 10, and the pressure control is controlled by the pilot spool valve 18 for pressure control. The generation of peak pressure that occurs in a short period of time that cannot be fully responded to by the discharge amount control of the discharge amount pump 13 is suppressed by directly exhausting the hydraulic actuator supply pressure.

Further, this pressure valve 21 is connected to the variable discharge amount vane pump 13.
When the discharge amount reaches the minimum, it operates as a pressure setting valve.

On the other hand, regarding the pressure increase in the main pipeline on the primary side of the flow control valve 14, when the primary pressure exceeds a predetermined value with respect to the secondary pressure of the flow control valve 14, the main pipeline is connected to the tank 1.
A pressure compensating valve 22 that communicates with 0 is provided, and is separated from the hydraulic pressure supplied to the hydraulic actuator to suppress the pressure rise in the primary side main pipe to a predetermined pressure.

Further, this pressure compensation valve 22 is configured such that the flow rate set by the flow rate control valve 14 is the minimum discharge amount of the variable discharge amount pump 13, for example, 1.
It also serves to return the excess discharge amount to the tank 10 when the discharge amount is reduced to 0.01 Jtorr or less.

The hydraulic control device of the present invention having such a configuration and operation includes a flow control valve 14, a sequence valve 16, a pilot spool valve 17 for pressure control, and a flow control valve 17 for pressure control, which are included in the block 23 surrounded by a chain line Pilot spool valve 1
B, throttle 19, remote control relief valve 20
, the pressure valve 21 and the pressure compensation valve 22 are each incorporated into a single unit, and this hydraulic control unit is integrated into the hydraulic actuator side or the variable displacement pump side.

The advantage of unitizing the block 23 in this way is that the pilot line required between the block 23 and an external device is the pilot line 24 that supplies control hydraulic pressure to the control actuator 13a of the variable displacement pump 13. Since the other pilot pipes can all be built into the unit, the shape and dimensions of the pilot pipe are uniquely determined, and the pilot pipe 24 connected to the control actuator 13a has already been Since the oil flows through the pipe, the stability of the hydraulic control device is not affected even if the length or shape of the pipe changes.

Therefore, by unitizing the block 23, in addition to improving the control responsiveness described above, control stability can be significantly enhanced, and piping work during assembly is also facilitated.

As explained above, according to the hydraulic control device of the present invention, flow control (in the case of vane pumps, hydraulic pressure to the control actuator) controls the discharge amount of the variable discharge pump so that the flow rate is set by the flow control valve. Since the control hydraulic pressure (control that changes the amount of eccentricity depending on the supply) is supplied directly without going through a throttle, etc., the responsiveness of flow rate control is improved, and the variable discharge volume pump maintains a fixed discharge volume when the flow rate is below a predetermined flow rate. Since it operates as a pump, the low-speed operation of the cylinder can be stabilized and reliably achieved by the restriction of the flow rate control valve.Furthermore, since the variable discharge amount pump delivers a predetermined amount of discharge even when the cylinder is stopped, the flow rate when the load starts is reduced. The responsiveness of the control device can be improved.

On the other hand, since the sequence valve provided on the secondary side of the flow control valve prevents the pump pressure from falling below a certain pressure, the flow response is improved even under low load.

Furthermore, the pilot pressure for pressure control is transferred to the secondary side of the flow control valve,
In other words, since the pressure is taken directly from the supply pressure to the cylinder load, it is possible to sharpen the cant-off characteristics of a variable displacement pump using pressure control. , the overshoot of the peak pressure that occurs in the cylinder is reduced, and damage to the cylinder is reliably prevented.

Furthermore, by incorporating the above-mentioned joint venture into one unit, the shape and dimensions of the pilot pipe for the joint venture can be uniquely determined without changing according to the equipment used, and therefore appropriate It is also possible to supply pilot pressure, thereby significantly improving control stability.

[Brief explanation of the drawings] Fig. 1 is a hydraulic circuit diagram showing an example of a conventional hydraulic control device, Fig. 2 is a graph showing the pressure at each part when the cylinder end is reached, and Fig. 3 is a hydraulic circuit diagram showing an example of a conventional hydraulic control device. FIG. 1 is a hydraulic circuit diagram showing an embodiment of the invention. 1.13...Variable discharge amount pump, 2,14...
...Flow control valve, 3...Cylinder, 4...
... Directional switching valve, 5.17 ... Pyront spool valve for flow control, 6.18 ... Pilot spool valve for pressure control, 7.20 ... Relief valve for remote control, 8.11,19...
・Dispersion, 9.22...Pressure compensation valve, 10...
...Tank, 12,23...Block, 16
... Sequence valve, 21 ... Pressure valve,
24... Pilot pipe line, 15... Variable throttle.

Claims (1)

[Claims] 1. In a hydraulic control device that controls the operating speed and operating force of a load such as a hydraulic actuator by adjusting supply oil pressure and flow rate, the discharge amount is varied within a range where the supply flow rate is equal to or higher than a predetermined value, and the supply flow rate is a variable discharge rate pump that maintains a constant discharge rate when is less than or equal to the predetermined value; a flow rate control valve that is provided in the main line of the variable discharge rate pump and that variably sets the flow rate supplied to the hydraulic actuator; A sequence valve is provided on the secondary side of the valve and opens the flow path to the load when the pump discharge pressure exceeds a set pressure, and the flow rate is controlled based on the pilot pressure taken out from the secondary side of the flow control valve. When the differential pressure across the control valve is above a certain value, the control actuator of the pump is switched to a position where the pressure is communicated with the tank to throttle the discharge amount, and when the differential pressure across the control valve is below the certain value, control hydraulic pressure is supplied to the control actuator of the pump. and switch to a position to increase the discharge amount, and furthermore, when the control actuator of the pump is communicated with the tank, the flow rate is equipped with an orifice that narrows down the pilot pressure so as not to obstruct the return of oil to the tank of the control hydraulic pressure by the pilot pressure. A control pilot spool valve, a restriction provided in a pilot pipe taken out from the main pipe which is the secondary side of the sequence valve, and a tank when the pilot pressure supplied through the restriction exceeds the relief set pressure. a remote control relief valve that communicates with the throttle to generate a differential pressure for pressure control at the throttle, and throttles the discharge amount of the pump when the differential pressure generated across the throttle is equal to or higher than a certain value; a pressure control pilot spool valve that supplies control hydraulic pressure to the control actuator of the pump to increase the discharge amount when the load is stopped and maintains the load supply pressure at a predetermined circuit setting pressure when the load is stopped; inputting the discharge pressure of the pump; a pressure compensation valve that operates to discharge pressure when the discharge pressure is a predetermined value or more; and a pressure compensation valve that communicates with the tank when the load supply pressure exceeds a predetermined value that exceeds the relief setting pressure while the remote control relief valve is in operation. A hydraulic control device comprising: a pressure valve for discharging surplus oil from a load; 2. Each of the flow rate control valve, flow rate control pilot spool valve, remote control relief valve, pressure control pilot spool valve, pressure compensation valve, and pressure valve and their pilot pipes are incorporated into one horn unit. Hydraulic control device according to claim 1, characterized in that it has all its features. 3. The hydraulic control device according to claim 2, wherein the unit is provided on a variable discharge amount pump side or a cylinder load side.