JPS5824672Y2 - Actuator control device in hydraulic closed circuit - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an actuator control device in a hydraulic closed circuit for excavator turning and other hydraulic closed circuits.

As shown in FIG. 1, a conventional control device of this type connects a hydraulic motor or other hydraulic actuator a to which a load such as an excavator revolving body is connected and a reversible variable hydraulic pump b through pipes c and d. a hydraulic closed circuit e, and the hydraulic pump b
A hydraulic feedback device consisting of a piston f that controls the discharge amount and the discharge direction and a servo switching valve g that controls the action of the pilot pressure fluid on the piston f is provided, and the switching operation of the switching valve g is controlled by this. A formula is known in which the pressure of the pipe C9d is applied in opposite directions via the feedback circuits i and j, and the pressure of 1 is applied to a pilot circuit that is arbitrarily applied in the opposite direction.

According to this, for example, when fluid pressure is applied to the pilot circuit k, the servo switching valve g is switched to the position g', and the pressure of the fluid pressure source m is applied to the 1 side of the piston f, so that the fluid Hydraulic pump b, which had not been discharging fluid, starts discharging fluid into conduit C, and the pressure of conduit C is introduced into servo switching valve g through feedback circuit i to oppose the pressure in the pilot circuit. Therefore, when the pressure in the pipe line C becomes equal to the pressure in the pilot circuit, the switching valve g automatically returns to the neutral position, the piston f stops at the moving position, and the hydraulic pump b discharges fluid. Continuing, when the pressure in the conduit C becomes higher than the operating pressure of the switching valve g, the switching valve g moves to a position "g" to operate the piston f so that the discharge amount of the hydraulic pump b decreases; It is possible to control the pressure when the speed of the actuator a increases.

In this case, when the hydraulic motor b is decelerated, pressure is generated in the pipe d, which switches the servo switching valve g to the closed position via the feedback circuit j, and applies brake pressure in the closed circuit e. There are disadvantages that should never occur.

The present invention aims to eliminate such disadvantages, and the hydraulic actuator 1 and the reversible variable hydraulic pump 2 are connected by pipes 3 and 4 to form a hydraulic closed circuit 6, and the hydraulic pump 2 is , a hydraulic feedback device 9 consisting of a piston 7 that controls the discharge amount and direction of the piston 7 and a servo switching valve 8 that controls the action of the pilot pressure fluid on the piston 7 is provided, and the switching operation of the switching valve 8 is fed back to the piston 7. circuit 10
The pressures of the lines 3, 4 acting in opposite directions through 11 and the pilot circuit 12 optionally acting in opposite directions.
．． 13, each feedback circuit 10.11 has an opposite pilot circuit 12,1.
Pilot check valve 14, which is released by the pressure of 3.
It consists of 15 parts.

The piston 7 is connected to a swash plate or other device provided in the hydraulic pump 2 that changes the pump discharge amount and reverses the discharge direction. When the piston 7 slides, for example, to the left or right from the neutral position, the hydraulic pump 2 discharges fluid into the pipe line 3 or 4, and the larger the sliding distance, the greater the flow rate.

Reference numeral 16 indicates a pilot pressure source, and when the servo switching valve 8 is switched to its switching position (8a or 8b), the pressure source 16
pressure acts on one side of the piston 7 to actuate it.

17 and 18 are brake circuits.

To explain its operation, when fluid pressure is applied to the pilot circuit 12, the servo switching valve 8 switches to the switching position 8a, the pilot check valve 15 is simultaneously released, and the pressure of the fluid pressure source 16 operates the piston 7. Therefore, the hydraulic pump 2 discharges fluid into the conduit 3 to drive the actuator 1 such as a hydraulic motor.

Since the piston 7 continues to slide so that the switching valve 8 closes the circuit thereto, the discharge amount of the hydraulic pump 2 increases during that time.
The actuator 1 is accelerated, but the pressure in the line 3 to it acts on the servo switching valve 8 through the released pilot check valve 15 to counteract the pressure in the pilot circuit 12, thus causing the line 3 to The pressure in line 3 is the pilot circuit 1.
When the pressure reaches the pressure corresponding to No. 2, the servo switching valve 8 is pushed back to the neutral position to cut off the flow of pressure fluid into the piston 7.

Therefore, the hydraulic pump 2 continues to discharge a flow rate corresponding to the sliding distance of the piston 7, and drives the actuator 1 at a speed corresponding to the flow rate.

By appropriately changing the pressure in the pilot circuit 12, the pressure generated in the conduit 3 can be controlled and the acceleration of the actuator 1 can be changed.

If pressure is applied to the pilot valve 13, the switching valve 8 enters the position 8b and the pilot check valve 14 is released, and the hydraulic pump 2 discharges fluid into the pipe 4, but the switching valve 8 enters the position 8b and the pilot check valve 14 is released. The valve 8 is closed by the pressure of the conduit 4 and the circuit 13, as in the previous case.

When the actuator 1 is driven by the fluid discharged from the hydraulic pump 2 to the pipe line 3, in order to decelerate the actuator 1, the pressure fluid from the fluid pressure source 16 is applied to the piston 7 to reduce the discharge amount of the pump 2. To this end, the pressure in the pilot circuit 12 is reduced to act on the servo switching valve 8, and the throttle valve 8 is switched to the position 8b.

The pressure in the circuit 12 simultaneously acts on the pilot check valve 15 to open it.

Since the other pilot check valve 14 is in the closed state, the pressure in the pipe line 4 does not act on the switching valve 8, and the hydraulic pump 2
As the discharge amount decreases, the actuator 1 is decelerated.

Thus, according to the present invention, each feedback circuit 10.11 is released by the pressure of the pilot circuit 12.13 on the opposite side.

Since the pilot check valves 14 and 15 are provided, brake pressure can be automatically generated in the hydraulic closed circuit 6, which operates in forward and reverse directions, regardless of the operation control of the pump 2, which is convenient. Since only the circuit 6 is provided, the circuit 6 does not become complicated.

[Brief explanation of the drawing]

FIG. 1 is a diagram of a conventional control device, and FIG. 2 is a diagram of an embodiment of the device of the present invention. DESCRIPTION OF SYMBOLS 1...Hydraulic actuator, 2...Variable hydraulic pump, 3.4...Pipe line, 6...Hydraulic closed circuit, I...Piston, 8...Servo switching valve, 9... Hydraulic feedback device, 10.11... feedback circuit, 1
2.13...Pilot circuit, 14,15...Pilot check valve.

Claims (1)

[Scope of utility model registration request] A hydraulic actuator 1 and a reversible variable hydraulic pump 2 are connected through pipes 3 and 4 to form a hydraulic closed circuit 6, and the hydraulic pump 2 is equipped with a piston 7 for controlling its discharge amount and direction, and a pilot therefor. A hydraulic feedback device 9 consisting of a servo switching valve 8 for controlling the action of the pressure fluid is provided, and the switching operation of the switching valve 8 is connected to a feedback circuit 10.
The pressures of said lines 3, 4 acting in opposite directions via 11 and a pilot circuit 12, optionally acting in opposite directions.
13, each feedback circuit 10.11 has an opposite pilot circuit 12, 13.
Pilot check valve 14.1 released by the pressure of
Actuator control device in a hydraulic closed circuit.