The pressure compensated variable displacement pump is widely used as a power supply in hydraulic systems. Although this variable displacement pump is efficient from the viewpoint of low energy loss compared to a fixed displacement pump with a relief valve, load control characteristics are degenerated when used in a servo control of load position or velocity, because the pump dynamics influences on load control dynamics. Thus, the knowledge of dynamic properties of this pump is important for the evaluation of hydraulic servo systems. In this thesis the following studies have been accomplished.
Firstly, the exact nonlinear 4-th order model to represent the pump dynamics has been derived, and the values of model parameters have been determined for a given pump by simple expriments and parameter identification technique.
Secondly, the nonlinear characteristics of the pump dynamics have been investigated by comparison of the response of pump outlet pressure, and these responses have been obtained through experiments and computer simulation performed for various sizes of the step input.
Lastly, the influences of parameter variation on the pump dynamics have been investigated by computer simulations for the 4-th order model.
Based upon these research, the pump dynamics found to be highly nonlinear for operating conditions and input variation sizes, and the degree of influence of each parameter was explained in some details.
