Abstract: Hydraulic multi-actuator technology powered by a centralized energy source is widely adopted in engineering machineries, with the advantages of large output force and high power density. But the fatal drawback of this method is the low energy utilization efficiency. Especially for the compound action of the multiple actuators, it is difficult to find an effective solution to the excessive throttling losses caused by load difference. Therefore, a load difference equalization system through electro-hydraulic energy storage is proposed. The principle of the electro-hydraulic composite energy storage and regulation is used to control the non-driving chamber pressure of the actuators, so that the driving chamber pressure of each actuator remains equal. On the basis of the same set of hardware, the throttling losses caused by load difference are effectively reduced, and the gravitational potential energy of the working device is efficiently recovered. Firstly, the velocity and pressure control characteristics of the single actuator are tested. On this basis, the compound action characteristic of the multiple actuators of the proposed system is studied with the hydraulic excavator as the application object. Simulation and experimental results show that the proposed system has good trajectory tracking performance and pressure control characteristics. Additionally, compared with the electro-hydraulic flow matching system, the throttling losses and energy consumption of the proposed system are reduced by 75% and 12.7% respectively under the combined action of the boom and bucket. The energy recovery efficiency of the system is 30.3%. Meanwhile, the coordination of the multi-actuator compound operation is improved as well. The novel energy-saving scheme is also applicable to other engineering machinery with multiple actuators.

Key words: load difference equalization, energy recovery, energy saving, engineering machinery