Improvement of Damping Characteristics of Hydrostatically Driven Hydraulic Excavator

This paper presents a system concept of a hydro-statically driven hydraulic excavator. In this system, pumps and actuators are connected each other. Then, the speed of actuators is controlled by operation of pump delivering flow rate. Herein, a hydraulic excavator has 7 actuators and 4 pumps, and the connection/disconnection of each pump and actuator is controlled by 3×4 directional control valves. Microcomputers execute the following controls : maximum pressure limiting, pump absorption power control for prevention of engine stall, transient vibration damping, maximum acceleration limiting and resolved motion rate control of the excavator's arm. Furthermore, this paper shows method for improvement of damping characteristics of the hydrostatically driven hydraulic excavator. This method does not necessarily create additional energy loss because it is controlled by operation of the pump delivering the flow rate.