Hydraulic Engine Mount for Shock Isolation at Acceleration on the FWD Cars

Front wheel drive cars (FWD) with transversely mounted engine have presented several problem areas due mainly to its inherent dynamics, among which idle car shake and shock at acceleration are the conflicting problems in designing engine mounts. And this aspect is generally given higher priority in determining detailed specifications.

When the mounts are tuned to minimize idle car shake, they tend to enlarge the shock at acceleration causing a problem. Conventional all rubber engine mounts seem to have their limitations to solve this conflicting problems.

In this paper in order to reduce the shock at acceleration, it is shown analytically that the non linearity of spring rate characteristics of the mount must be lower, and/or damping rate higher. And hydraulic engine mount can have lower dynamic stiffness at small deflection and higher damping rate at large deflection together. An advanced bush type hydraulic roll mount is developed to improve the shock isolation.