Independent Metering Control Characteristic Analysis And Expermental Research Of Excavator Electric-hydraulic Control System

The hydraulic system is widely used in the fields of aerospace,ship,mobile vehicle and steel industry because of its large power output ratio,fast response,high control precision and remote control.At the same time,the integration of the hydraulic system and electronic control technology promoted the electro-hydraulic control system application rapid growth.However,the hydraulic system is a kind of transmission with high energy consumption in exchange for good handing control performance,and its application is increasingly challenged by other transmission technologies(such as electrical transmission and mechanical transmission).As a preprquisite,to meet the performance requirements,achieving energy saving control has become one of the focal areas of the hydraulic field.The conventional valve control hydraulic system often uses a sliding spool with multiple metering orifices to control inlet and outlet oil way of the hydraulic actuators.If the meter-in flow rate is regulated,the meter-out flow rate is changing simultaneously,As a result that the loss of metering is coming.So it results in higher energy consumption and lower efficiency.The technology of independent metering control of the inlet and outlet technology can achieve both the flow rate control and pressure control,thus it can avoid the repeated metering losses of the conventional valve control hydraulic system.According to the limitation of the metering control of the conventional valve control hydraulic system,this paper proposed a valve control system solution with both excellent control characteristics and low energy consumption.In this paper,the key issues of energy saving performance,pressure compensation performance,motion control performance are studied in detail for the independent metering control system.Based on the opening manners of the tranditional four-way hydraulic system,seven typical opening manners of independent metering system are proposed,and the static characteristic is analyzed.Using the state-space equation,the dynamic characteristic simulation model has been built.And the optimal opening manner of independent metering system is obtained by the dynamic analysis.Based on the mechanical-hydraulic pressure compensation principle of the load sensing system,as for the meter-in and meter-out orifices of the independent metering system can be independently regulated,the meter-in pressure compensation method and the meter-out pressure compensation method are studied.Based on the calculated equations of the pump pressure,the optimal manner of the meter-in pressure compensation system and meter-out pressure compensation system is explored,and the static characteristics are analyzed.Based on the upstream compensation principle and downstream compensation principle,the simulation models of independent metering valve system with upstream compensation and load sensing system are built.The energy saving performance of the independent metering valve system with upstream compensation is studied by the analysis of the two systems with load lifting conditions.As the existence of the dead zone of the proportional valve,the double direction equivalent compensaction method of dead zone is proposed,and the pressure signals is filtering by the inertia element adaptive filter,and the feedforward and feedback compound control strategy with region segmentation of expert PID is proposed for improving the linear control characteristic of independent metering control system.Based on the proposed solution of independent metering valve control system,the 6T excavator is taken as the research object.The single actuator motion and multiple actuators motion have been researched by experimental research,the theoretical analysis and experimental results show that the the energy savings of independent metering system in the boom,arm and bucket single motions have been increased 39.5%,36.6% and 32.3% respectively compared with the existing system;the energy savings of independent metering system in the compound motion of boom and bucket,the compound motion of boom and arm,the compound motion of arm and bucket,the compound motion of boom,arm and bucket have been increased 20.2%,25.6%,27.8% and 20.8% respectively.