Experimental investigation of power assisted steering pump noise for housing material change from cast iron to aluminium

Noise and vibration have an important influence on a customer's perception of vehicle quality. In this research, the major power-assisted steering pump noise propagation mechanism is determined. Noise and vibration comparison tests have been completed for subjectively good and bad cast-iron housed pumps, as well as for an aluminium housed pump. Decoupling tests for the steering rack disconnected from the engine cross member have also been conducted. The test results are discussed for evaluation of the housing material change from cast iron to aluminium, paying special attention to the key noise characteristics which distinguish 'bad pumps' from 'good pumps'.