In the working process of excavator, the potential energy of the arm is converted into heat by valve throttle, which results in great energy loss. If the lost energy can be recovered, it can not only reduce the cost of excavator, but also save energy and protect the environment.
In order to recover the potential energy wasted in the working process of hydraulic excavator, many studies have been carried out at home and abroad. The method of recovering and utilizing the potential energy of the moving arm can be summed up into the following five types. First, the accumulator is directly recycled, and the oil when the arm drops is introduced into the hydraulic accumulator through the control valve, and the potential energy of the arm is converted into hydraulic energy. The recovered energy can be used to drive the cooling system or other auxiliary devices. Second, the potential energy when the arm drops is converted into electric energy by hydraulic motor-generator and stored in super capacitor or battery, which is mainly used in hybrid excavator. The third is closed pump controlled hydraulic cylinder circuit, accumulator or super capacitor to recover potential energy. Fourth, on the basis of the original control circuit, the potential energy of hydraulic transformer and accumulator is increased, or directly utilized. Fifth, the principle of liquid gas energy storage is used to directly balance the weight of the working device.
Through the analysis of the existing potential energy recovery methods, it can be seen that the energy transfer chain is short and the conversion efficiency is high. However, the existing practical applications are to add a hydraulic energy storage cylinder to balance the arm weight in the dual hydraulic cylinder drive arm loop. For small machines with single hydraulic cylinder driving arm, it is difficult to arrange additional hydraulic balance cylinder due to space limitation. Therefore, the three hydraulic cylinders combined with accumulators are used to form the circuit principle of the integration of hydraulic energy storage and driving of the arm, and the potential energy of the arm is directly recovered and reused efficiently. This method is suitable for both single hydraulic cylinder driven minicomputer and double hydraulic cylinder driven large machine. The advantage is that there is no need to change the original excavator arm structure, and the potential energy and hydraulic energy are directly converted, and the regeneration efficiency is high.