Linear analysis of automotive hydro-mechanical mount with emphasis on decoupler characteristics

Abstract

A hydro-mechanical mount for an automotive engine can provide superior stiffness and damping characteristics which may vary with frequency and excitation amplitude. In order to better understand such a passive device, a linear time-invariant model with lumped mechanical and fluid elements is proposed and validated by comparing dynamic stiffness spectra predictions with experimental data over the frequency range 1–50 Hz. Special emphasis has been placed on the modeling of both free and fixed type decouplers. Most, if not all, of the prior models have been shown to be the special cases of the proposed four-degree-of-freedom system model. Several reduced or simplified forms of this model have been examined, and parametric design studies have been carried out. The performance of a typical hydro-mechanical mount has also been compared with the conventional rubber mount for the resonance control and vibration isolation characteristics. Inappropriateness of the low frequency model beyond 100 Hz is identified. Other limitations associated with the linear models are identified and future research issues have been discussed briefly.