Research On The Pressure-flow Characteristic Of An Electro-hydraulic Proportional Load Sensing Pump

Along with the whole world's shortage of energy and the deterioration of environment day by day, people must enlarge the protection of ecological environment and implement the sustainable development. As main actuation and control modes, hydraulic technique must develop toward high efficiency and energy saving. Therefore, to improve the hydraulic system's efficiency from the power source, research on hydraulic pump must be done. The pressure and flow control characteristic of the electro-proportion load sensing pump which is remarkably efficient and energy-saving used in hydraulic systems is studied in this paper.The mathematical model of the electro-proportion load sensing pump is established, according to its working principle. The control block diagram and the transfer function have been acquired. Referring to the control theory knowledge, it is mainly analyzed how each parameter affects the load sensing pump's stability. This provide the following research with a good theory instruction.The development of virtual prototype technology makes the simulation research more precise. Virtual prototype technology is used, and first the variable piston pump's mechanism model is established in Pro/e, then import the model in ADAMS to obtain a dynamic model of the piston pump. Models of valves in the load sensing pump such as the proportion throttle valve, proportion pressure valve and control valve are developed in AMESim simulation software, and also the stroking mechanism. With the interface document of ADAMS and AMESim, the models AMESim and the ADAMS can join up. This kind of union simulation technique can use the respective superiority of many different softwares. And the simulation model established and the simulation result will be more accurate. Therefore, the union simulation technique develops very fast, and has been very popular in the research institute. In order to acquire accurate value of flow force on the valves, CFD software FLUENT is used to simulate the flow field in both throttle valve and control valve, and to calculate the relationship between the opening and flow force. Referring to the value of flow force in FLUENT, the flow force coefficient in AMESim can be adjusted to the accurate value.The influence of damping orifices and volumes to the control characteristic of load sensing pump is analyzed through the simulation. A good match of the damping orifices improves the dynamic and steady-state control characteristic. It is also studied that using proportional solenoid can decrease the bad influence of flow force to the whole pump, however, using proportional solenoid with displacement sensor can't do.It's very necessary to carry out experiments to verify the accuracy of simulation analysis. So at last some experiments about the damping orifices'influence are carried out. The results prove that the theoretical analysis above and the simulation research are correct and instructive. The improvement is advantageous to the pressure and flow control characteristic of the load sensing pump.