OBJECTIVE AND SUBJECTIVE VIBRO-ACOUSTICS ASSESMENT FOR PUMPS OF VEHICULAR HYDRYAULIC POWER STEERING SYSTEMS

In this study the moan and whine noises of the pumps of the Hydraulic Power Steering systems are investigated experimentally through the measurements of the dynamic hydraulic pressure in the pump outlet installed in a test stand. The vibro-acoustic performance of the pumps is evaluated applying two objective metrics. One of them consisted of the pressure amplitude sum and the other identified the maximum amplitude, in the frequencies of interest (fundamental frequency and harmonics). The results of the dynamic pressure measurements of pumps installed in a test stand are compared with the subjective qualification of the same pumps installed in an actual vehicle by the grades given by trained listeners.