Determining Source Fluidborne Noise Characteristics of Automotive Fluid Power Pumps

A new method, the “3 Pressures/ 2 Systems” method, is developed for determining source flow ripple and internal impedance of fluid power pumps. The method integrates exclusively an on-line measurement technique for the speed of sound in the fluid and a technique for eliminating flow disturbance effect on pressure sensors into the basic principle used in the existing “2 Pressures / 2 Systems” method. The new method has an inherent potential to yield results with higher accuracy and higher confidence. The high accuracy of the method is confirmed by the comparison of measured and predicted pressure ripple in a pump-pipe-valve system. Then, the method is applied to automotive fluid power pumps - power steering pumps. The measured results of source flow ripple and internal impedance are presented.