Research On A Novel Pilot Control Mechanism Of Variable Displacement Axial Piston Pump

This paper took pressure and electric flow control axial piston pump as researching object. Through depth analysis of its working principle, mathematical model of pressure control system was established. The transfer function was analyzed on frequency domain, the result of which revealed the fact that the phase margin of constant pressure control is small, so a targeted solution with bypass leakage to enhance the pressure stability of small displacement working condition was proposed. In addition, with flow force theory and FLUENT simulation, the remarkable result of reducing flow force with oblique orifice restrictor was show on this paper. Finally, the solution was validated by AMESIM simulation and experimental test.The main contents of this paper are as follows:In chapter one, the classification and working principle of control progress of the variable displacement pump was introduced, through comparing the development of variable displacement axial piston pump and control characteristics at home and abroad institutions, the necessity of this research was pointed out.In chapter two, the mathematical model of the system was built up. The unbalanced load torque formula of the swash plate was derived by force analysis and appropriate methods was proposed to compensate it, which would be helpful to accumulate theoretical foundation for high speed and pressure pump design and optimization.In chapter three, the transfer function of the system was analyzed on frequency domain, the result of which revealed the fact that the phase margin of constant pressure control is small, so a targeted solution with bypass leakage to enhance the pressure stability at small displacement working condition was proposed, It would provide a good solution for axial piston pump with pressure control to adapt the periodic operation of small flow and pressure retain after rapid journey. As to the steady flow force interference to electric proportional displacement control, this chapter showed the quantitative effect of reducing flow force with the help of oblique orifice restrictor by FLUENT simulation and study on flow force theory, which was meaningful for proper choose of the proportional electromagnet, improvement of the forerunner level structure and the energy conservation and emissions reduction, etc.In chapter four, the pressure stability at small displacement of the axial piston pump and the preparatory scheme was validated and optimized by AMESIM simulation and experimental test.In chapter five, the experiment platform was built up to provide an experimental basis for the hydraulic pump to test performance, innovate structure and optimize performance. The remarkable result of pressure stability improvement at small displacement of the pump was showed through flow step dynamic characteristics experiment of the regulator valve.In chapter six, the main work of this paper was summarized and the subsequent research direction was pointed out.