Passive Engine Mounts-Some Directions for Further Development

A car engine suspension system has to comply with numerous constraints, sometimes controversial, thus making engine mounts design and optimization an extremely difficult task. Active mounts, although having important advantages, are still more expensive and less reliable. The paper shows that there is substantial room for improvements in passive engine mounts, if some concepts proven in vibration isolators for other applications are utilized. These concepts include: use of specific non-linear characteristics to obtain constant natural frequency in a broad weight-load range as well as to make captive variable stiffness mounts; use of materials with high internal damping as well as materials with highly amplitude-dependent damping and stiffness; use of mounts combining two resilient elements with intermediate mass or spring-connected damper; and utilizing benefits of small-size mounts.