Vibration Control of Engine Roll and Bounce Using Hydraulic Engine Mounts

This paper shows the optimum design method for hydraulic engine mounts. Engine mounts have been developed recently to significantly reduce the vibration in car bodies caused by engines. The resonance peaks of conventional engine-mounting systems can not be suppressed sufficiently. Hydraulic engine mounts are able to suppress the resonance peaks by using the fluid reaction effect of the fluid enclosed in the mounts. The design was recently modified by trial and error experiments. Due to lack of information on a suitable design, the ability of this design has not been effectively demonstrated. In this paper, after the mount is analyzed, its optimum design formula is obtained in a simple and useful manner, similar to the design equation for dynamic absorbers. This design formula is applied for designing two hydraulic engine mounts to control engine vibrations in the roll and bounce modes. The effectiveness of the formula is confirmed theoretically and experimentally.