Excavator is an earth moving machine that uses a bucket to excavate materials that are higher or lower than the bearing surface, and loads them into a transport vehicle or discharges them to a stockyard. There are many types of hydraulic systems for excavators, which can be classified according to different aspects. Center system and closed center system can be separated from multi-channel valve.
Open center system means that when the valve rod of the change-over valve is in the middle position, the hydraulic oil discharged by the hydraulic pump directly flows back to the oil tank through the middle oil passage of the change-over valve. When the valve rod is reversed, the intermediate oil passage begins to close, and the pressure of the working oil passage gradually increases until the load pressure is overcome to drive the actuator.
Closed center system means that when the reversing valve stem is in the middle position, the hydraulic pump only provides the flow required for internal leakage under the maximum pressure of the system. When the valve rod is reversed, the hydraulic pump only provides the flow required by the system, eliminating the inherent bypass oil return loss of the open center system.
After comparing and analyzing the speed regulation performance, the compound operation performance of the actuator acting at the same time, the degree of freedom of selecting the oil supply flow of each valve rod, energy saving and productivity, dynamic performance and so on. It can be seen that the closed center load sensitive pressure compensation is a new hydraulic system developed to make the hydraulic system better meet the complex working conditions of excavators.
