Investigation Of Differential Load Sensing Servo Valve Control System

One of the promising technique for the energy saving of the electrohydraulic servo control system is the application of load sensing control. Preliminary theoretical and practical application of that load-sensing technical mainly concerns the single-directional cylinder. However, 4-way servo valve can not be used in two-way drive load sensitive servo system while double-acting hydraulic were widely used in the large-scale application of engineering practice,because the system is only able to load sensitive components of the hydraulic capacity of a cavity pressure "sensitive"; hydrostatic transmission system from load control of sensitive dual-role-cylinder, by reversing valve or spindle valve switching control is not feasible, because the servo positioning in the process of reversing valve or valve spindle switching, the load-min regulation will cause pressure fluctuations so that the servo system of quality deterioration, will result in serious system instability. Load sensing dual role of the hydraulic system control components of the implementation of such limitations, has been seriously restricted in the electro-hydraulic servo control system applications.Therefore, this thesis presents P-Q valve control differential load sensing servo system solution, the key control component P-Q valve is particularly emphasized.The contents of thesis are as follows:In chapter one,the relevant research literatures are at first summarized.Then the purposes and contents of the thesis are briefly described.In chapter two,the working principle of the P-Q valve control differential load sensing servo system is introduced briefly,then the static mathematical model is built up and static analysis and working position are discussed by means of the simulation to the model.In chapter three,a mathematic modeling of the P-Q valve differential load sensing servo system is established by considering linear and nonlinear factors of the valve,the simulations are carried out to obtain the stability of the system and the dynamic response to the step signals.In chapter four, experiment and experimental equipments of the P-Q valve differential load sensing servo system is introduced,experiments for static and dynamic characteristics of speed were done.The experiment results show that double-acting control of single-directional cylinder could be realized well by differential load sensing servo system,which have a stable speed response and quick dynamic response time. And the energy could be saved in the application on load sensing technology.In chapter five,a summary and a prospect to the research work in the thesis are put forward as the conclusion.