JPS591885B2 - Hydraulic circuit control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has one variable displacement pump, a plurality of actuators driven by the variable displacement pump, and respective open/close valves provided corresponding to each actuator. One of the actuators is selected, and the corresponding on-off valve is opened, and the selected actuator and the variable displacement pump are connected in a closed circuit, and depending on the operation amount and direction of the operation lever, the selected actuator is connected to the variable displacement pump. The present invention relates to a hydraulic circuit control device that controls the operating speed and operating direction of the selected actuator based on the discharge amount and discharge direction of a controlled variable displacement pump.

FIG. 1 is a dimensional diagram of a conventional hydraulic circuit control device.

In the figure, 1 is a variable displacement pump, 2 and 3 are hydraulic cylinders driven by pump 1, and 4°5 is hydraulic cylinder 2.
, 3, and 6 and 7 are on-off valves that selectively disconnect the oil passages between the pump 1 and the cylinders 2 and 3, and the on-off valves 6.7 are solenoid valves 6a, 7a, poppets 6b, 6c, 7b,
γC, shuttle valves 6d, 6e, 6f, 7d, 7
It is composed of e and γf.

8 and 9 are check valves, 10.11 is a flushing valve, 1
2 is a charge pump, 13 and 14 are IJ IJ-no valves,
15 is a tank, 16.17 is an operating lever for operating cylinders 2 and 3, respectively, and 19 is an operating lever 16.1.
By inputting the signal No. 7, the pump 1 discharge amount variable control device
This is a control circuit that outputs signals to the swash plate tilt angle control device 18 and the solenoid valves 6a and 7a.

In this hydraulic circuit control device, the on-off valves 6.7 are in a closed state (ie, poppets) 6b, 6c, and 7b.

7c is closed, when the operating lever 16 is operated, the cylinder 2 is selected by the signal from the operating lever 16, the solenoid valve 6a is switched, and the on-off valve 6 corresponding to the cylinder 2 is opened. The cylinder 2 and the pump 1 are connected in a closed circuit, and the discharge amount and discharge direction of the pump 1 are controlled by the amount and direction of operation of the control lever 16, and the operating speed and direction of the cylinder 2 are controlled by the pump. It is controlled by the discharge amount and discharge direction of 1.

In this case, since the solenoid valve 6a has an operation delay, even if the operating lever 16 is operated, the on-off valve 6 remains closed for a while, whereas the discharge amount of the pump 1 is reduced by the operating 1/bar 16. As the pressure increases in accordance with the amount of operation of Become.

When the on-off valve 6 opens in this state, the pump 1 and the cylinder 2 are suddenly connected, the pressure inside the cylinder 2 changes rapidly, and the cylinder 2 suddenly operates.

Unfortunately, when the cylinder 2 is attached to a hydraulic excavator or the like, the vehicle body shakes significantly and becomes inoperable for a while.

This invention was made to solve the above-mentioned problems, and provides a control device for a hydraulic circuit that prevents the actuator from suddenly operating due to confinement pressure generated in the pipeline when the actuator starts operating. The purpose is to

In order to achieve this objective, in the present invention, when the output signal of the operating lever that operates the selected actuator is no longer zero, the signal is delayed by the time when the on-off valve corresponding to the selected actuator opens, and the output signal is adjusted to a variable capacity. A dead time generating device is provided which outputs to the variable discharge amount control device of the pump.

FIG. 2 is a diagram showing a control device for a hydraulic circuit according to the present invention.

In this hydraulic circuit control device, a dead time generating device 20 is provided, and this dead time generating device 20 has the following functions:
When the operating lever 16.17 is operated from the neutral position to the operating position and the signal from the operating lever 16.17 is no longer zero, the swash plate tilt angle control device delays the signal by the time the on-off valves 6 and 7 open. Output to 18.

In this case, for example, when the operating lever 16 is operated from the neutral position, the signal is immediately transmitted to the solenoid valve 6a, but the signal from the operating lever 16 is transmitted to the swash plate tilting angle control device 18 after a predetermined time. Therefore, after the solenoid valve 6a is switched and the on-off valve 6 is opened, the discharge amount of the pump 1 increases.

Therefore, no confinement pressure is generated within the conduit 23, and the pressure in the hydraulic cylinder 2 does not change suddenly.

FIG. 3 is a diagram showing another hydraulic circuit control device according to the present invention.

In the figure, 18a is a displacement meter that detects the tilt angle of the swash plate of the pump 1, 18b is a swash plate driving piston, 18c to 18f are electromagnetic valves, and 21 is a hydraulic pump.When the electromagnetic valves 18c and 18d are switched, the piston 18b is Move to the right and select solenoid valve 1
8e.

When 18f is switched, the piston 18b moves to the left in the drawing, and when solenoid valves 1sa and 18e are switched, the piston 18b is locked.

Then, the swash plate of the pump 1 is operated by the piston 18b, and the discharge amount and discharge direction of the pump 1 are controlled.

22 is a control device including a dead time generator; 22a is a multiplexer that sequentially switches and inputs analog signals from the operating levers 16 and 17 and the displacement meter 18a; and 22b is an A/D converter that converts the analog signals from the multiplexer 22a into digital signals. D converter, multiplexer 22a and A/D
The converter 22b constitutes an input circuit.

22c is a memory circuit that stores the dead time generation procedure, the priority determination procedure for the cylinders 2 and 3, the switching procedure for the on-off valves 6 and 7, the discharge amount of the pump 1, the discharge direction control procedure, etc.;
An output circuit 22e for controlling the d-swash plate tilting angle control device 18 and the on-off valves 6 and 7 reads out the procedure stored in the memory circuit 22c, decodes it, and uses the signal from the A/D converter 22b. This is a control circuit that controls the output circuit 22d.

Next, the operation will be explained with reference to the flowchart shown in FIG.

First, the signals from the operating levers 16 and 17 are sent to the multiplexer 2.
2a, A/D converter 22bf reading, then operation lever 1
6. Determine whether both signals in 17 are zero.

When the signals from the operating levers 16 and 17 are both zero, the displacement meter 18a detects the swash plate tilt angle of the pump 1, and the swash plate tilt angle is zero degrees, that is, the discharge amount of the pump 1 is zero. When it is determined whether or not, and the discharge amount of pump 1 is zero,
A signal for closing the on-off valves 6 and 7 and a signal for maintaining the discharge amount of the pump 1 at zero are output from the output circuit 22d, and the process returns to the beginning.

If the tilt angle of the swash plate of the pump 1 is not zero at A, the output circuit 2 outputs a signal that makes the tilt angle of the swash plate of the pump 1 zero.
Output from 2d and return to the beginning.

If it is determined that the operation signal is still being output from either of the operation levers 16 and 17 at B, cylinders 2,
After determining the priority of step 3 and the signal values of the operating levers 16 and 17 and selecting the actuator, the previous operating lever 16 is selected.
．． 17 Both signals are not zero, and the actuator selected by C is the same as the actuator selected last time. When the selected actuator is the same as the previously selected actuator, the discharge amount of the pump 1 is controlled in accordance with the signal from the operating lever 16 or 17, and the process returns to the beginning.

If it is determined in D that the signals of both the previous operating levers 16 and 17 are zero, or that the actuator selected in C is different from the actuator selected last time, the swash plate tilt angle of the pump 1 is zero degrees. If the swash plate tilt angle is not zero degrees, the output circuit 22d sets the swash plate tilt angle of the pump 1 to zero degrees to make the discharge amount of the pump 1 zero, and returns to the beginning.

When it is determined that the swash plate tilt angle of the pump 1 is 0 degrees in step E, a switching signal is output from the output circuit 22d to the on-off valve 6 or on-off valve 7 to switch the on-off valve 6 or on-off valve 7, and then It is determined whether the dead time has passed or not, and if the dead time has not passed, a signal is outputted from the output circuit 22d to maintain the tilt angle of the swash plate of the pump 1 at zero degrees, and the process returns to the beginning.

Then, B-F etc. are repeated, and when it is determined that the dead time has passed at F, the discharge amount of the pump 1 is controlled according to the amount of operation of the operating lever 16 or 17.

Next, the operation will be explained over time with reference to FIG.

Initially, when the output of the operating lever 16.17 is zero, in order to keep the cylinders 2 and 3 stopped, the on-off valve 6.7, ie, poppet 6b.

6c, 7b, and 7c are closed, and the discharge amount of the pump 1 is zero.

At time t1, the operating lever 16 is operated, and the operating lever 16
At the same time as the output signal is output, an input signal is input to the solenoid valve 6a of the on-off valve 6, but since there is a delay in the operation of the solenoid valve 6a, popets 6b and 6c begin to open at time t2, and at time t3. Poppets) 6b and 6c are fully open.

Waiting for this delay in operation of the on-off valve 6, the discharge amount of the pump 1 starts to increase at time t4 when the on-off valve 6 has finished opening completely, and at time t5 the discharge amount of the pump 1 increases to the operating lever 1.
The value corresponds to the operation amount of 6.

After this, when the operating lever 16 is returned to the neutral position at time t6, the discharge amount of the pump 1 begins to decrease at the same time, and at the time t
At 7, the discharge amount of the pump 1 becomes zero and the input signal to the solenoid valve 6a of the on-off valve 6 is cut off.

Then, due to the delay in the operation of the solenoid valve 6a, at time t8 poppets 6b and 6c begin to close, and at time t9 poppets 6b
, 6c are completely closed.

Furthermore, when the output signal of the operating lever 17 is output at time tto, the same operation as described above is performed.

Note that the control device 22 in the above embodiment may be configured by a microcomputer.

Further, in the above embodiment, the case of electrical control has been described, but other control, such as hydraulic control, may be used.

Further, in the above embodiment, the flow is looped several times to create dead time depending on the execution time, but a dead time routine may be created and the dead time may be spent there.

As explained above, in the hydraulic circuit control device according to the present invention, the discharge amount of the variable displacement pump increases after the opening/closing valve is opened, so that no confining pressure is generated. The actuator does not operate suddenly when the on-off valve is opened.

In this way, the effects of this invention are remarkable.

[Brief explanation of the drawing]

Figure 1 shows a conventional hydraulic circuit control device; Figure 2;
3 is a diagram showing a hydraulic circuit control device according to the present invention, FIG. 4 is a flowchart for explaining the operation of the hydraulic circuit control device shown in FIG. 3, and FIG. It is a graph which explains the operation of the control device of the hydraulic circuit shown. 1... Variable displacement pump, 2, 3... Hydraulic cylinder,
6.7...Opening/closing valve, 6a, ? a... Solenoid valve, 16.
17... Operation lever, 18... Swash plate tilting angle control device, 2001, Dead time generator, 22... Control device,
22a...Multiplexer, 22b...A/D converter, 22c...Storage circuit, 22d...Output circuit, 2
2e...control circuit.

Claims (1)

[Claims] It has 11 variable displacement pumps, a plurality of actuators driven by the pumps, and each on-off valve provided corresponding to each actuator, and one of the actuators is activated in response to a signal from the operating lever. At the same time, one corresponding on-off valve is opened and the selected actuator and the variable displacement pump are connected in a closed circuit, and the variable displacement pump controlled by the operation amount and operation direction of the operation lever is activated. In a hydraulic control device of a hydraulic circuit that controls the operating speed and operating direction of the selected actuator based on the discharge amount and discharge direction, when the output signal of the operating lever that operates the selected actuator is no longer zero, the signal A control device for a hydraulic circuit, comprising a dead time generating device that delays the opening time of an on-off valve corresponding to the selected actuator and outputs the delayed output to the variable discharge amount control device of the variable displacement pump.