Design And Parameter Study On The Flow Controlling Element With Displacement-Spring-Force Feedback Principle

With the developing of hydraulic technology, efficient and energy-saving pump control system has gotten great availability. Pump control system is becoming the emphasis of hydraulic system development. The pump-controlled system with little energy wastage and heat can apply to the high and medium power adjustable-speed system . In addition, because the load stiffness is large and gain and damp ratio is relatively constant, the hydraulic elements should be considered as linear structure. As the power and control component, the dynamic characteristic of variable displacement pump is an important reference of pump control system's quality. How to enhance response speed and precision of variable displacement pump is important to improve performance of pump-controlled system. The utility of simulation technology greatly shorten the research and exploitation progress of new products. Computer dynamic simulation is very valuable when hydraulic system is designed, analyzed, and modified.The main work could be described as follows:1. Referring to the JB63 series radial piston variable displacement pump, a variable displacement mechanism of variable displacement pump which is developed on the basis of displacement-spring-force feedback principle is designed. The simulation model of variable displacement pump is set up in SIMULINK of MATLAB. It studies systematically the influence of variable displacement mechanism and variable displacement pump parameters to its characteristic dynamic responses, and summarizes the immanent law of the variable displacement mechanism of variable displacement pump system, and provides theoretical basis for the electro-hydraulic control of variable displacement pump.2. Large displacement bent axis variable displacement piston pump has been widely used in various industrial fields. The constant pressure and permanent power control which will produce energy losses in use is the typical control system styles. If a controlling principle can be adopted to change pump's displacement, it will not only improve the control characteristics, but also increase the efficiency of the system. But due to a long stroke of the variable displacement mechanism and the difficult implementation of electronic close loop control, a principle of pilot type with displacement-force feedback is proposed to control the pump. The application of the principle to the variable displacement mechanism is discussed, the control system mathematical model was built up and the influence of system structure parameters on the variable discharge system is analyzed in the paper.Simulation results show that the dynamic characteristic of electro-hydraulic proportion controlling variable displacement pump using this displacement-spring-force feedback principle controller is very good. It have more simple structure, low cost, convenient control characteristics comparing with the electric feedback, however, it showed lower control precision.