EXPERIMENTAL STUDY ABOUT THE EFFECT OF POWERTRAIN MOUNTING SYSTEM ON VEHICLE INTERIOR NOISE

The effect of bracket and mount on the interior noise of a passenger car was studied by experiment systematically under an accelerated condition, taking the modal frequency of an engine side bracket and the dynamic stiffness of mount as variables. First, brackets with high, medium and low modal frequencies were designed and trial-manufactured, then the contrast experiment was carried out. The results indicate that:the overall level of interior noise is determined mostly by low-band noise, secondly by medium-band noise, and the contribution of high-band noise can be ignored. The effect of brackets on interior noise is caused by resonance-induced medium-band noise. Thusly, high frequency brackets with first-order modal frequency greater than 700 Hz can refine medium-band noise effectively. Secondly, the contrast experiment results between hydraulic mount and the one without fluid indicate that mount stiffness can affect low-band noise and therefor determine the overall level of interior noise. On the basis of above researches, the combination scheme was implemented with high frequency brackets and right up-side down hydraulic mount. Then low-band and medium-band noise are refined, and the above conclusions can be validated.