| With the increasing concerns of automotive interior noise, it is necessary to further understanding of power steering moan, which becomes very annoying during parking operations when the car is stationary and the steering wheel is fully turned. Recent research [Smith et al. (1995); Takeuchi and Adachi (1995); Longmore and Johnston (1994); and Phillips (1996)] has shown that this kind of noise is generated by the power steering pump.; In this study, a comprehensive system model is developed and is the first such model to integrate all the system components (steering wheel, column, pump, rack and pinion unit, and transmission line) in effort to predict power steering pump-induced noise and vibration. Experiments were conducted to verify the system model. Overall good agreement was obtained between experimental data and simulation predictions.; To incorporate the dynamic characteristics of system components, empirical and mathematical models are employed. A method using experimentally determined transfer matrix coefficients to optimally estimate the complex sound speed in hydraulic hose sections is developed. Good results were obtained for several hoses at frequencies below 1000 Hz. Also a model for the rotary valve and power cylinder that uses experimentally determined point impedances to estimate the flow characteristics in the rotary valve is developed. Experimental testing showed that the direction (forward or reverse) of a coaxial tuning cable in a hose section has little effect on the transmission loss, and that mean flow in the transmission line can be ignored in the analysis.; This study provides a systematic approach to investigate the power steering noise and vibration created by the pump excitation. The mathematical models presented can also be applied to the analysis of noise in other hydraulic systems, such as those used in air conditioners and power plants. |
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