Steering system is responsible for providing a precise directional control to the vehicle. The Hydraulic Power Assisted Steering (HPAS) system is commonly used in passenger cars and commercial vehicles due to low cost.
Power steering pump develops and delivers required pressure to provide assistance while steering. It reduces the effort required to steer the vehicle. Steering pump (generally vane type) is a critical part providing hydraulic pressure assistance to rack and pinion or gear box. Basically the hydraulic pump noise can be classified as ‘Moan Noise’ and ‘Whine Noise’. The noise generated by power steering pump pressure pulsation is termed as ‘Moan’ and ‘Whine’ based on operational induce frequency. As power train becomes quieter, it becomes more perceivable at typical engine operating speed range and gives impression of poor refinement and quality.
This abstract describes the experimental measurement technique to investigate, analyze and quantify the moan noise and elaborate on design of experiments along with its effect on steering system’s moan noise and performance. It also covers the comparative benchmark analysis of different power steering pump designs and its contribution in the moan noise. This research work has helped us to come out with new test method to assess different steering system noises at component, system and vehicle level. Measurements revealed a strong correlation between pump pressure pulsation and steering system moan noise.
The subject research work has resulted in elimination of moan noise to achieve better NVH performance in passenger car by optimizing the steering pump and steering line design.