Use of Binaural Measurement and Analysis Techniques in the Establishment of Steering Pump Design Tolerances for Noise, Vibration and Harshness Performance

The objective of the present work was to establish a correlation between steering pump cam ring profile location and steering system performance for noise, vibration and harshness (NVH). Once this correlation was established, the secondary objective was to determine acceptable cam profile position tolerances from the standpoint of NVH performance. These objectives were accomplished through the use of binaural measurement and jury evaluation of vehicle interior noise.

Cam rings were manufactured for this study with profiles shifted a predetermined distance away from the nominal position. These cams were built into steering pumps and these pumps were in turn installed in a vehicle. Vehicle interior noise and pump housing vibration measurements were made to quantify the steering system noise performance associated with each cam ring. The interior noise recordings were played back for a jury comprised of engineers familiar with steering system noise. This jury then subjectively evaluated steering system noise for each steering system. These subjective evaluations were used along with objective measurements to fully quantify steering pump cam ring NVH performance.

A clear correlation between the steering pump cam ring profile location and subjective appraisal of steering system noise is demonstrated. Specifically, the further from the nominal position the cam profile is shifted, the less acceptable the noise performance of the steering system becomes. These analyses were used to satisfy the secondary objective of the present work; i.e. establishment of steering pump cam ring profile location tolerances.