JPH0777204A - Shock relaxing hydraulic circuit for hydraulic actuator - Google Patents

Abstract

PURPOSE:To provide a hydraulic circuit for relaxing oil pressure shock due to an abrupt pressure rise in a secondary-side line based on a sudden drop of load on the work of a hydraulic actuator. CONSTITUTION:A pressure regulating valve (cartridge valve 6) or a flow control valve for controlling back pressure is provided in a secondary-side line L2 of a hydraulic actuator 2, and an automatic closing circuit 8 for automatically closing the secondary-side line L2 at the time of abrupt pressure rise in the secondary-side line L2 due to sudden reduction of load on a work W of the hydraulic actuator 2 is provided in the secondary-side line L2. Further, a pressure reducing circuit 9 for switching the pressure of pressure oil in a primary-side line L1 to low pressure is provided in the primary-side line L1 of the hydraulic actuator 2.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shock mitigating hydraulic circuit for a hydraulic actuator that operates using hydraulic pressure as a drive source.

[0002]

2. Description of the Related Art A device for converting oil energy into mechanical energy is generally called a hydraulic actuator, and is roughly classified into a hydraulic motor that converts mechanical energy into torque by rotating motion and a hydraulic cylinder that converts force into linear force. FIG. 3 shows a conventional basic hydraulic circuit when a hydraulic cylinder is used as a hydraulic actuator. The hydraulic actuator 2 supplied with hydraulic oil by a hydraulic pump supplies mechanical energy to the work W. 3, relief valve 3 and the cartridge valve 5 and the solenoid valve (4-way valve) 4 and is connected to the primary side line L _1, the secondary side line L ₂ and the cartridge valve and the solenoid valve 7 Connected. 10 is an oil tank. During normal use, the solenoid A of the solenoid valve 7 is energized, the solenoid C of the solenoid valve 4 is de-energized, and as the piston 2a of the hydraulic actuator 2 advances, the pressure oil in the secondary side line L ₂ passes through the cartridge valve 6. Then, it is returned to the oil tank 10.

[0003]

In such a hydraulic circuit 100 for a conventional hydraulic actuator, the work W such as a stick-slip phenomenon is generated during the operation of the hydraulic actuator 2 (while the piston 2a is moving forward). Load on the secondary side L ₂
The pressure of the hydraulic oil rises rapidly, energy cannot be absorbed within the working pressure, and the speed of the piston 2a rapidly accelerates.
A hydraulic shock could occur. As a result, there were problems such as shortening the life of the machine and abnormally high noise.

[0004]

[Means for Solving the Problems] By solving the above problems,
To alleviate the hydraulic shock, in the hydraulic circuit of the present invention, the secondary line of the hydraulic actuator is provided with a pressure adjusting valve or a flow control valve for back pressure control, and the load on the work of the hydraulic actuator is suddenly reduced. The secondary line is provided with an automatic closing circuit that automatically closes the secondary line when the secondary line suddenly increases in pressure due to the A pressure reducing circuit for switching the pressure of the pressure oil in the line to a low pressure is provided.

[0005]

In the shock mitigating hydraulic circuit of the present invention, even if the load of the work is suddenly reduced and the pressure of the hydraulic oil on the secondary side line of the hydraulic actuator rises sharply, the automatic closing circuit provided on the secondary side line. The hydraulic oil return line of the secondary side line is controlled in flow rate to absorb the hydraulic shock and exert a damper function, and the hydraulic oil pressure of the primary side line of the hydraulic actuator is provided in the primary side line. The pressure reducing circuit works to switch from high pressure to low pressure to reduce the energy supplied to the hydraulic actuator.

[0006]

Embodiments of the present invention will now be described in detail with reference to the drawings. 1 and 2 relate to an embodiment of the present invention,
Fig. 1 is a shock-relief hydraulic circuit diagram of the hydraulic actuator,
FIG. 2 is a shock mitigating hydraulic circuit diagram of a hydraulic actuator showing another embodiment. As shown in FIG. 1, the shock mitigating hydraulic circuit 200 of the present invention includes a cartridge valve 5, a relief valve 3, and a relief valve 3 in a primary side line L ₁ of a hydraulic actuator 2.
In addition to the solenoid valve (4-way switching valve) 4, a pressure reducing circuit 9 is incorporated. The pressure reducing circuit 9 includes a 2-port switching valve 9a, a pressure adjusting valve 9b, and an oil tank 10, and the solenoid valve 9a is connected by pilot piping from an automatic closing circuit 8 described later. In the secondary line L ₂ of the hydraulic actuator 2,
An automatic closing circuit 8 is incorporated in addition to a cartridge valve 6 having a throttle for flow rate adjustment, a solenoid valve (four-way switching valve) 7, an oil tank 10. The automatic closing circuit 8 is a cartridge valve 8
a and solenoid valve (2-way switching valve) 8b and solenoid valve (4-way switching valve)
8c and the oil tank 10.

The operation of the shock mitigating hydraulic circuit 200 of FIG. 1 constructed as above will be described. First, during normal use, the solenoid A of the solenoid valve 7 and the solenoid B of the solenoid valve 8c are excited, and the solenoid C of the solenoid valve 4 is de-excited.
The hydraulic pump 1 is driven to supply hydraulic oil to the primary side line L _1, and the piston 2a of the hydraulic actuator 2 moves forward to apply mechanical energy to the work W. At this time, most of the hydraulic oil in the secondary side line L ₂ flows to the cartridge valve 8 a and is returned to the tank 10, and a small amount of hydraulic oil in a part is returned to the oil tank 10 via the cartridge valve 6. on the other hand,
When the load of the work W is suddenly reduced during the operation of the hydraulic actuator 2 and the pressure of the hydraulic oil in the secondary side line L ₂ is rapidly increased, the pilot line L _{3 connected} to the solenoid valve 8b of the automatic closing circuit 8 of the hydraulic oil is bought out the urging force of the compression spring of the solenoid valve 8b closes the electromagnetic valve 8b flowing to the electromagnetic valve 8b, the results of cartridge valve 8a is closed, hydraulic fluid in the secondary-side line L ₂ is Since only the cartridge valve 6 whose flow rate is controlled can return to the oil tank 10 and the flow rate is controlled, the movement of the piston 2a that rapidly advances is absorbed, and the shock is absorbed. At the same time, the hydraulic oil flows to the pilot line L ₄ connected to the solenoid valve 9a of the pressure reducing circuit 9 described above, the solenoid valve 9a changes from the closed state to the communication state, and the action of the pressure adjusting valve 9b set to the low pressure acts. As a result, the hydraulic oil in the primary side line L ₁ is also reduced in pressure, and the sudden acceleration of the piston 2a in an emergency is alleviated.

As described above, the load on the work W is suddenly increased.
Can reduce the hydraulic shock due to
In addition to the circuit shown in Fig. 1, the shock absorbing hydraulic circuit shown in Fig. 2 is used.
A similar operation can be performed in the path 300.
Only the parts of the embodiment of FIG. 2 different from those of FIG. 1 will be described.
Next line L₁ Then, abolish cartridge valve 5 and release
Change the valve 3 to the balance piston type relief valve 3A,
Secondary line L₂ Then, let the cartridge valve 6 be the flow control valve.
(Throttle valve) In addition to 6A, automatic closing circuit 8 configuration
As shown in the figure, turn off the sequence valve 8A and the direction switching valve 8B.
It is a combination of the replacement operation valve 8C and the solenoid valve 8D.
is there. Also in the circuit of FIG. 2, the solenoid A,
B is excited (solenoid C is not excited) and piston 2a
With the advance of the secondary line L₂ Hydraulic fluid is a directional valve
It is returned to the oil tank 10 via 8B. In case of emergency
Pressure oil flows to the pilot pipe of the sequence valve 8A.
Pilot line L_Four And pilot line L _Five Pressure
The two-port switching valve 9a of the pressure reducing circuit 9 is brought into a communicating state with oil.
In addition to shutting off the switching operation valve 8C, the directional switching valve 8
The B return line to the oil tank 10 is shut off. According to
And the secondary line L in an emergency₂ The return line of the flow rate adjustment
Only the valve 6A is provided to reduce hydraulic shock. On the other hand, 1
Next line L₁ 2 port switching valve 9a is a pilot line
L_Four The pilot pressure oil supplied from the
Therefore, the same pressure as the pressure adjusting valve 9b set to low pressure is not
The balance piston type relief valve 3A also changes the set pressure.
Primary line L₁ The operating pressure of is converted to low pressure.

As described above, in the shock mitigating hydraulic circuit of FIGS. 1 and 2, even if the pressure of the hydraulic oil in the secondary side line L ₂ of the hydraulic actuator 2 suddenly rises, the automatic closing circuit 8 or The decompression circuit 9 operates to mitigate a sudden hydraulic shock and avoid an adverse effect on the machine, and an efficient back pressure control of the hydraulic actuator is performed.

[0010]

As described above, in the present invention,
Since the hydraulic shock in the emergency of the hydraulic actuator is automatically avoided and energy is absorbed / relaxed, the machine is protected and the generation of noise is suppressed, so that the life of the equipment is prolonged and the operability and maintenance are improved. improves.

[Brief description of drawings]

FIG. 1 is a shock mitigating hydraulic circuit diagram of a hydraulic actuator showing one embodiment of the present invention.

FIG. 2 is a shock mitigation hydraulic circuit diagram of a hydraulic actuator showing another embodiment of the present invention.

FIG. 3 is a hydraulic circuit diagram of a conventional hydraulic actuator.

[Explanation of symbols]

1 Oil Pump 2 Hydraulic Actuator 2a Piston 3 Relief Valve 3A Balance Piston Relief Valve 4 Solenoid Valve (4 Way Switching Valve) 5 Cartridge Valve 6 Cartridge Valve 6A Flow Control Valve 7 Solenoid Valve (4 Way Switching Valve) 8 Automatic Closing Circuit 8a Cartridge valve 8b 2-port switching valve 8c Solenoid valve (4-way switching valve) 8A Sequence valve 8B Directional switching valve 8C Switching operation valve 8D Solenoid valve (4-way switching valve) 9 Pressure reducing circuit 9a 2-port switching valve 9b Pressure adjustment valve 10 Oil tank A solenoid B solenoid C solenoid L ₁ 1 primary line L ₂ 2 primary line L ₃ pilot line L ₄ pilot line L ₅ pilot line

Claims (1)

[Claims] 1. A secondary side line of a hydraulic actuator is provided with a pressure adjusting valve or a flow rate control valve for controlling back pressure, and a sudden pressure of the secondary side line is caused by a sudden load reduction of a work of the hydraulic actuator. An automatic closing circuit that automatically closes the secondary side line when rising is provided in the secondary side line, and the primary side line of the hydraulic actuator is depressurized to switch the pressure oil pressure of the primary side line to a low pressure. A shock absorbing hydraulic circuit for a hydraulic actuator that has a circuit.