This work demonstrates a practical method for predicting vehicle-level automotive steering system NVH performance from component-level NVH measurements of hydraulic steering pumps. For this method, in-vehicle measurements were completed to quantify vehicle noise path characteristics, including steering system structure borne, fluid borne and airborne paths. At the component level, measurements of steering pump reaction forces, sound power and dynamic hydraulic pressure were also completed.
The vehicle-level measurement data was used to construct NVH transfer functions for the vehicle. These transfer functions were in turn combined with the pump component data measured on a test stand to create a prediction for steering pump order vehicle interior noise. The accuracy of these predicted values was assessed through comparison with actual vehicle interior noise measurements.
The results of this study yielded a useful and practical tool for predicting steering system vehicle noise from component-level data, as well as a contribution analysis of the relative importance of the three steering system noise paths. In particular, at engine idle speeds, the fluid borne noise path dominated vehicle steering system NVH to the degree that other noise paths (i.e. airborne and structure borne) could be disregarded. However, this assumption could not be made at higher engine speeds, where interior noise tended to be dominated by the airborne and structure borne transfer paths.