Hydraulic Fluid-Borne Noise Measurement and Simulation for Off-Highway Equipment

High pressure hydraulic systems are widely used in off-highway applications, such as agricultural and construction machines. Flow ripple generated by pump or motor combined with resonant behavior from hydraulic circuits often lead to very high pressure ripple levels. Large pressure ripple in the hydraulic circuit can cause audible hydraulic whine noise, which results in both overall noise level increase and sound quality degradation. To aid in designing quieter hydraulic systems, a fluid-borne noise test bench was built to characterize both active and passive hydraulic components. The test bench is based on frequency-domain transfer matrix approach. It can be used to measure flow ripple and impedance of hydraulic pump or motor, as well as transfer matrix of passive components such as hydraulic hoses or attenuators. Measured flow ripple is an effective noise predictor for hydraulic-intensive machines, thus can be used to rank and compare pumps or motors from different suppliers. The measured characteristics of components can be imported to the lumped parameter modeling tool to simulate and optimize the fluid-borne noise behavior of the entire hydraulic circuit. This paper presents a few examples of active and passive components testing and simulation.