Modelling and experimental validation of the displacement of a check valve in a hydraulic piston pump

A variety of methods have previously been applied to modelling hydraulic check valves. While the theoretical framework has been established, robust experimental validation of check valve models is lacking. When present, validation methods typically rely on measurements of pressure differential or flow rates, from which check valve dynamics are inferred. In this paper, a lumped parameter model is constructed for a disc style check valve used to control the inlet and outlet flow of a piston pump. Pressure, spring, contact, stiction, and flow forces are investigated to determine which have a significant effect on the check valve dynamics. An experimental pump circuit is constructed and an acrylic sight glass is installed on the check valve manifolds. A method of directly measuring the check valve position during operation using a Laser Triangulation Sensor (LTS) is developed by applying Snell's law to the air-acrylic and acrylic-oil interfaces and calculating laser refraction to obtain a relationship between valve position and LTS voltage output. Modelled valve position and flow rates are compared to experimental data for three sets of operating conditions – baseline, high speed, and high pressure. In all three cases, modelled inlet and delivery valve displacement closely agree with experimental measurements. Error between predicted and measured flow rates is less than 3% for all cases.