JPS591884B2 - Hydraulic circuit control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has one variable displacement pump and a plurality of actuators driven by the variable displacement pump, and one of the actuators is controlled by each on-off valve provided corresponding to each actuator. and the variable displacement pump are selectively connected in a closed circuit, and the operating speed and operating direction of one actuator connected to the variable displacement pump are controlled by the discharge amount and discharge direction of the variable displacement pump, The present invention relates to a hydraulic circuit control device that switches the closed circuit connection from one actuator of the variable displacement pump to the other actuator by opening and closing each on-off valve.

FIG. 1 is a diagram showing 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 cut off communication between the oil passages between the pump 1 and the cylinders 2 and 3, and the on-off valves 6 and 1 are solenoid valves 6a and γa.

Poppet sb, 6csγb, 7c, shuttle valve 6a,
One of the cylinders 2.3 and the pump 1 are selectively connected in a closed circuit by opening and closing the on-off valves 6 and 1 consisting of 6e, 6t, 7d, 7e and H.

8 and 9 are check valves, 10° and 11 are flushing valves, 1
2 is a charge pump, 13.14 is a relief valve, 15 is a tank, 16°1γ is an operation lever for operating the cylinders 2 and 3, respectively, and 19 is a signal input from the operation levers 16 and 17 to operate the pump 1. This is a control circuit that outputs the swash plate tilt angle control device 18 and the electromagnetic valves 6a and 7aK signals.

In this hydraulic circuit control device, for example, the on-off valve 6
is open and the on-off valve γ is closed (that is, popetsu) 6b, 6c
7b and 7c are closed, the operating speed and operating direction of the cylinder 2 are controlled by the discharge amount and discharge direction of the pump 1.

In this state, when the operating lever 17 is moved from the neutral position to the operating position, if cylinder 3 has priority over cylinder 2, then
First, a signal is issued from the control circuit 19 to make the discharge amount of the pump 1 zero, and then a cut signal of the solenoid valve 6a and a large signal of the solenoid valve 1a are output simultaneously, and the cylinder 2 of the pump 1 is turned off to the cylinder 3 of the pump 1.
Closed circuit connection switching is performed.

However, because there is a delay in the operation of the solenoid valves 6a and poppets 6b and 6c, the on-off valve 7 is closed before the on-off valve 6 is closed.
starts to open, the hydraulic circuit on the cylinder 2 side and the hydraulic circuit on the cylinder 3 side are connected, and if the loads 4 and 5 are unbalanced, the cylinders 2 and 3 will suddenly operate.

For this reason, when the cylinders 2 and 3 are attached to a hydraulic excavator or the like, the vehicle body shakes significantly and becomes inoperable for a while.

In addition, in order to solve the above-mentioned problem, two on-off valves should be replaced with one.
The round part of the spool can be shaped so that when one on-off valve closes, the other on-off valve opens. However, if there are three or more actuators, , separate on-off valves must be provided.

This invention was made to solve the above-mentioned problem, and when switching the closed circuit connection of the other actuator to the variable displacement pump, one actuator and the other actuator are connected, and the actuator suddenly changes. The object of the present invention is to provide a control device for a hydraulic circuit that does not operate.

In order to achieve this objective, in the present invention, when switching the closed circuit connection of the other actuator to the variable displacement pump, the signal for opening the on-off valve of the other actuator is delayed by the time when the on-off valve of one actuator closes. A dead time generator is installed to output the dead time.

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 generation circuit 20 is provided, and for example, when the operating lever 1γ is operated from the neutral position to the operating position with the on-off valve 6 open and the on-off valve 7 closed, If cylinder 3 has priority over cylinder 2, the cut signal of solenoid valve 6a is output at the same time as operation lever 17 is operated, and the large signal of solenoid valve 7a is output after operation lever 17 is operated and on-off valve 6 is closed. Output is delayed.

Therefore, since the on-off valve 7 is opened after the on-off valve 6 is closed, the cylinders 2 and 3 are not connected, and even if the loads 4 and 5 are unbalanced,
join.

Cylinders 2 and 3 do not operate 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 drive piston, 18c to 18f are electromagnetic valves, and 21 is a hydraulic pump, including electromagnetic valves 18c and 1s.
When ti is switched, the piston 18b moves to the right in the paper,
When the solenoid valves 18e and 18f are switched, the piston 18b moves to the left in the drawing, and when the solenoid valves 18d 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, 17 and the displacement meter 18a; and 22b is an A/R 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.;
d is an output circuit for controlling the swash plate tilt angle control device 18 and the on-off valves 6 and 7; 22e reads out and decodes the procedure stored in the memory circuit 22c, and outputs a 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 Read the XA/D converter 22bf, then select the actuator based on the priority of the actuator and the output signal values of the control levers 16 and 17. Then, check whether the actuator selected at A is the same as the previously selected actuator. If it is determined that they are the same, the tilt angle of the swash plate of the pump 1 can be changed to the operation lever 16 or the operation lever 1.
Return to the beginning as the value corresponding to the output of 7.

In addition, when it is determined in B that the actuator selected in A is different from the previous actuator, it is first determined whether the swash plate tilt angle of the pump 1 is 0 degrees, and if the swash plate tilt angle is not 0 degrees, the pump 1 After setting the swash plate tilt angle to 0 degrees, return to the beginning.

When it is determined that the swash plate tilt angle of the pump 1 is 0 degrees in step C, the on-off valves 6 and 1 are closed, and then it is determined whether or not the dead time has passed, and it is determined that the dead time has not passed. Sometimes, the output circuit 22 outputs a signal that keeps the on-off valves 6 and 1 closed.
Output from d and return to the beginning.

Then, after repeating steps A to D, etc., when it is determined that the dead time has passed at step D, the on-off valve 6 or the on-off valve 1 is opened.

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

When cylinder 2 is operating and cylinder 3 is not operating, the output of operating lever 16 is not zero, the output of operating lever 1γ is zero, and the discharge amount of pump 1 is equal to operating lever 1.
6b and 6c are open, and the input of the solenoid valve 6a is not zero, and the input of the solenoid valve 6a is open.
The input is zero, and poppets 7b and 7c are closed.

In this state, when the operating lever 17 is moved from the neutral position to the operating position at time t1, the cylinder 3 is moved to the cylinder 2
If the priority is higher, the discharge amount of the pump 1 starts to decrease, and when the discharge amount of the pump 1 becomes zero at time t2, the input to the solenoid valve 6a becomes zero.

Then, due to the delay in the operation of the solenoid valve 6a, the sockets 6b and 6c begin to close at time t3, and at time t4, the sockets 6b and 6c begin to close.
6c is completely closed.

In order to wait for this delay in the operation of the on-off valve 6, a large signal is input to the solenoid valve 1a at time t when the on-off valve 6 is completely closed, and poppets 7b and 7c begin to open at time t6.

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, when switching the closed circuit connection of the other actuator to the variable displacement pump, after the on-off valve of one actuator is closed, the on-off valve of the other actuator is closed. Since the on-off valve of the actuator is open and null, there is no connection between one actuator and the other.
Even if the loads on both actuators are unbalanced, the actuators will not operate suddenly.

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

[Brief explanation of drawings]

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,
6.1...Opening/closing valve, 5a, γa...Solenoid valve, 16゜1
γ...operation lever, 18...swash plate tilt angle control device,
20... Dead time generator, 22... Control device, 2
2a... multiplexer, 22b... A/D converter,
22c...Storage circuit, 22d...Output circuit, 22e
...Control circuit.

Claims (1)

[Claims] It has 11 variable displacement pumps and a plurality of actuators and actors driven by the same, and one of the actuators and the variable displacement pump are selected by each on-off valve provided corresponding to each actuator. The operating speed and operating direction of one actuator connected to the variable displacement pump are controlled by the discharge amount and discharge direction of the variable displacement pump, and one actuator of the variable displacement pump is connected in a closed circuit to the variable displacement pump. In a hydraulic circuit control device that switches the closed circuit connection from one actuator to the other actuator by opening and closing each on-off valve, when switching the closed circuit connection of the other actuator to the variable displacement pump, the on-off valve of the other actuator is switched. 1. A control device for a hydraulic circuit, comprising a dead time generator that outputs an open signal after delaying the closing time of an on-off valve of one actuator.