Research on Optimal Control of Excavator Negative Control System Based on Secondary Controllable Main Valve

In order to optimize the energy efficiency and action coordination of negative control excavators, a secondary control circuit of main valve is proposed, which sets an electric proportional pressure reducing valve between joystick-pilot valve and main valve, so that main valve opening can be adjusted twice according to the actual working conditions to meet system control requirements. This paper takes the swing-dipper system as the research object, and studies the overload action and compound action of swing motor and dipper cylinder. In order to reduce the overflow caused by overload, an on-demand flow control strategy is designed to match the pump-valve flow with the demand flow of actuators. In order to solve the problem of uncoordinated compound actions caused by load difference, a flow-ratio control strategy is designed to make the flow ratio of actuators equal to the stroke ratio of joysticks. The system performance test of a 37-ton excavator was carried out, and a simulation model of the swing-dipper system was built. Based on the test and model, the two control strategies were simulated, and the results indicate that, compared with the original hydraulic main valve, the proposed secondary controllable main valve and its control strategies can reduce the motor/pump overflow when the motor/cylinder is overloaded, and can adjust the actuator flow ratio when the excavator performs a compound action, thereby improving the energy saving and manipulation performance of the excavator.