IDENTIFICATION OF FLUID-POWER COMPONENT BEHAVIOR USING DYNAMIC FLOW-RATE MEASUREMENT

An identification concept is developed utilizing direct measurement of the transient flowrate and pressure to determine the dynamic characte ristics of fluid power components. The fundamental experimental approa ch is discussed and applied to a range of sizes of a bladder-type accu mulator and also to a single-stage pressure relief valve. The gas char ging characteristic of the accumulator was determined for three differ ent sizes and during dynamic operation. It is shown how the nitrogen g as index of compression varies during operation and a relationship bet ween the index and instantaneous flowrate is proposed. Measurements ob tained with the pressure relief valve were used to identify its dynami c impedance in the frequency domain via time series analysis and trans formation. The predictions are compared with a linearized mathematical model showing good correlation over a wide frequency band. A particul ar feature was found to be the use of the impedance magnitude-frequenc y asymptotes for validation of the steady state pressure-flowrate char acteristic.