According to the power source driving the main distribution valve, the basic types of operation control system of hydraulic excavator can be divided into mechanical lever type, hydraulic type, pneumatic type and electrical type. The hydraulic system of the hydraulic excavator has large flow and high pressure, and the driving force of the valve core of the main distribution valve is large. In order to reduce the labor intensity of operators and facilitate reasonable layout, hydraulic, pneumatic and electrical operation control systems are mostly used. This page mainly introduces the hydraulic control system.
The hydraulic control of hydraulic excavator depends on the oil pressure to promote the action of the valve core of the main distribution valve. Its oil circuit can be independent or led out from the main oil circuit system. At present, there are three types of hydraulic control: mechanical feedback follow-up, integrated control valve and main distribution valve and pilot control. The latter is mostly used, which is divided into pressure generation type and pressure reducing valve type.
Pressure generating pilot valve operation is a kind of remote operation. When the pilot valve spool is pulled, the oil output from the pump enters the right side of the pilot valve and pushes the spool of the main distribution valve to the left. In this operation mode, the outlet pressure of the pilot valve is controlled by the movement of the valve core and the throttling area. Because the pilot valve spool stroke maintains an approximate proportional relationship with the main distribution valve spool stroke, it has good handling performance.
The pressure reducing valve pilot valve controls the movement of the valve core of the main distribution valve, which is also indirectly controlled by hydraulic first guidance. The difference is that the pressure reducing pilot valve is adopted. When the handle of the pilot valve is pulled, the pressure oil from the operating pump first enters the pilot valve, and then pushes the slide valve of the main distribution valve to move left or right to control the operation of the hydraulic motor.
