Dynamic Analysis of a Variable Displacement Pump

The ability of a variable displacement pump to respond to a control signal is a critical factor in assessing the dynamic performance of the circuit in which the pump is located. The need for a comprehensive dynamic response model of the pump is necessary if new techniques for control are to be realized. This paper presents a mathematical model, based on fluid mechanics considerations, of a variable displacement pump modulated by a hydraulic control signal. Many of the coefficients in the model depend on the pump model. In this study, a Vickers No. PVB5 pump is used. The describing equations are complex, nonlinear, and comprehensive in the initial model. Some nonlinear terms are simplified using linear approximations without significantly affecting accuracy. The model is subjected to a simulated pressure control signal and the output of the swash plate rotary displacement compared to an experimentally generated displacement time trace. The model and the experimental results show a good correlation.