JPH0640962Y2 - Hydraulic control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a hydraulic circuit for rapidly discharging and slowly supplying pressure oil to one side of an actuator, and more particularly to a hydraulic control circuit for a cylinder of a die casting machine.

[Prior Art] A conventional hydraulic control circuit will be described with reference to FIG.
A poppet valve 31 that opens and closes the flow path by alternately applying pressure to a pair of opposed cylinder chambers 22, 23 is provided between the rod side of the actuator 19 and the tank 44A, and between the actuator 19 and the hydraulic power source 42. An on-off valve 46 is provided in the.

A 4-port switching valve 45 for switching the connection between the cylinder chambers 22 and 23, the hydraulic pressure source 42, and the tank 44B is provided in parallel with the opening / closing valve 46 between the poppet valve 31 and the hydraulic pressure source 42. The pilot line of the opening / closing valve 46 is connected to the cylinder chamber 23, and a throttle 47 for adjusting the flow rate discharged to the tank 44C in accordance with the pilot operation is inserted into the fluid path, and the cylinder port 23A is used to insert the cylinder. A slow return valve 48 is interposed in the pilot line connected to the chamber 23 so as to limit the flow only in the direction of discharge from the cylinder chamber 23 to the tank 44B.

When the switching valve 45 is in the illustrated state (de-energized), the on-off valve 46
Is closed because the pilot line communicates with the tank 44B, the pressure of the hydraulic pressure source 42 is applied from the cylinder port 22A to the cylinder chamber 22 of the pilot valve 31, and the cylinder chamber 23 receives the slow return valve 48 from the cylinder port 23A. , Switching valve 4
Since it communicates with the tank 44B via 5
Is lowered and the pilot valve 31 is fully opened. Therefore, the fluid discharged from the rod side of the actuator 19 passes through the poppet valve 31 and is discharged to the tank 44A, so that the actuator 19 moves leftward at high speed.

When the switching valve 45 is switched to the position opposite to that shown in the figure, the pressure oil from the hydraulic power source 42 enters the cylinder chamber 23 from the slow return valve 48 and the cylinder port 23A, and the cylinder chamber 22 becomes the cylinder port 22.
Since A communicates with the tank 44B via the switching valve 45, the piston portion 34 rises in the figure to close the poppet valve 31, and the opening / closing valve 46 is pushed open by the pilot line by the hydraulic pressure source 42 to open the actuator 19. Rightward movement is performed at a constant speed according to the supply amount of the hydraulic power source 42. At the rightward speed of the actuator 19, in order to adjust the opening degree of the opening / closing valve 46 so that the speed changes smoothly without a step during the transition from the start of the switching operation of the switching valve 45 until it becomes constant, the tank 44C is adjusted. The amount of oil returned to is adjusted by the opening of the throttle 47. Also,
At the rightward limit, the switching valve 45 is switched again to the position shown in the drawing to prepare for the leftward movement of the actuator 19.

[Problems to be Solved by the Invention] Supply and discharge of pressure oil to and from the rod side of the actuator 19 are controlled by a discharge-only poppet valve 31, a supply-specific open / close valve 46, and a switching valve 45 that controls these. Further actuator
When the switching valve 45 is operated to prepare for leftward movement in the rightward limit of 19 and the poppet valve 31 is opened at a normal speed, the high pressure oil enclosed in the rod side of the actuator 19 and the circuit communicating with it Is rapidly released and released to the tank 44A via the poppet valve 31 to cause a water hammer phenomenon.As a preventive measure, it is necessary to insert the slow return valve 48 and adjust the throttle 47 in relation to the on-off valve 46. In addition, there was a problem with many components.

[Means for Solving Problems] The other side of the actuator is selectively connected to a hydraulic pressure source such as an accumulator, is interposed in a flow path connecting one side of the accumulator and the tank, and is provided with a spring that normally closes to face each other. A one-side cylinder that connects a poppet valve that closes the flow path by alternately applying pressure to a pair of cylinder chambers and one side of the actuator and one of the cylinder chambers that closes the poppet valve when pressure is applied. A hydraulic control device including a port and a four-port switching valve that exclusively connects the other cylinder port connected to the other cylinder chamber to the hydraulic power source and the tank.

[Operation] When the switching valve 15 is at the illustrated position, the poppet valve 1 is fully opened to receive the fluid discharged from the actuator 19,
Since it is discharged to the tank 14A, the actuator 19 moves leftward at high speed.

When the switching valve 15 is switched to the position opposite to that shown in the figure, the elastic pressure of the spring 6 starts the operation of closing the poppet 3 and the pressure of the fluid supplied from the hydraulic pressure source 12 acts on the cylinder chamber 6, and at the same time the hydraulic pressure source 12 Pressure oil flows into the one side 20 of the actuator 19 and flows out into the tank 14A until the poppet valve 1 is closed. Therefore, when the actuator 19 moves to the right, the speed becomes slow and the poppet valve 1 is completely closed. Actuator
19 goes to the right at a speed according to the amount of oil supplied from the hydraulic power source 12. Switch the switching valve 15 to the position shown in the right-most limit Poppet valve 1
The actuator 19 is opened to prepare for leftward movement, but prior to the opening of the poppet valve 1, the switching valve 15 gradually stores the high pressure oil trapped in the one side 20 of the actuator 19 and the accompanying pipelines in the tank 14A. To the so-called decompression effect and does not cause the water hammer phenomenon.

[Embodiment] An embodiment of the present invention will be described in detail with reference to FIG.
19 is an actuator corresponding to the injection cylinder of the die casting machine, one side 20 of which communicates with the tank 44A and the other side 21
Is selectively connected to a hydraulic pressure source such as an accumulator and a tank (not shown), and is supplied with fluid from the hydraulic pressure source to move leftward at high speed. Upon receiving the supply, the other side 21 is opened to a tank (not shown) and the right side is moved. Reference numeral 1 denotes a poppet valve provided between the rod side of the actuator 19 and the tank 14A. A poppet 3 having a seat surface 11 at the front end and a piston portion 4 at the rear end is slidably inserted into the main body 2, and the piston portion The poppet 3 is repressed by a spring 6 from the back of the poppet 4 to the valve seat 10 formed in the main body 2.
The seat surface (11) is seated and the flow path extending in front of and behind the valve seat (10) is blocked. The cylinder 5 provided in the main body 2 of the poppet valve 1 is divided into two parts by the piston part 4, and the cylinder chambers are arranged opposite to each other.
22 and 23 are communicated with the switching valve 15. The switching valve 15 is provided between the hydraulic pressure source 12 and one side 20 of the actuator 19, and the cylinder chambers 22 and 23 are communicated with the hydraulic pressure source 12 or the tank 14B by the operation of the switching valve 15, and the poppet 3 is shown in the figure. The poppet valve 1 is opened and closed by moving it up and down.

[Effect] The fluid supply to one side of the actuator is controlled only by the poppet valve and the switching valve that controls the opening and closing of the poppet valve, and when switching to discharge, the switching valve is contained in the circuit prior to the opening of the poppet valve. The water hammer phenomenon does not occur because the pressure being applied is gradually lowered.

Therefore, the installation and adjustment of the slow return valve can be omitted, and the opening / closing valve 46 and its associated throttle valve in the prior art can be omitted.
Since 47 is not required, it is effective in reducing equipment costs.

[Brief description of drawings]

FIG. 1 is a hydraulic circuit diagram partially illustrating a cross section for explaining the present invention, and FIG. 2 is a hydraulic circuit diagram partially illustrating a conventional example and partially including a cross section. 1 ... Poppet valve, 2 ... Main body, 3 ... Poppet, 4 ... Piston part, 5 ... Cylinder, 6 ... Spring, 10 ... Valve seat, 11 ... Seat surface,
12 ... hydraulic power source, 14A, 14B, 14C ... tank, 15 ... switching valve, 19
… Actuators, 22, 23… Cylinder chambers, 22A, 22B… Cylinder ports.

Claims (1)

[Scope of utility model registration request] 1. A pair of opposed cylinders that are selectively connected to a hydraulic source such as an accumulator on the other side of the actuator, are provided in a flow path connecting one side of the actuator and a tank, and are provided with springs that are normally closed. A one-side cylinder that connects a poppet valve that closes the flow path by alternately applying pressure to the chamber and one side of the actuator and one of the cylinder chambers that closes the poppet valve when pressure is applied. A hydraulic control device comprising a port and a four-port switching valve that exclusively connects the other cylinder port connected to the other of the cylinder chambers to a hydraulic power source and a tank.