Passive mounts/springs with negligible damping and low stiffness are highly effective in isolating vibration but have poor shock isolation characteristics. This and other contradictory traits of passive mounts, make the realization of an ideal, uncompromised isolation system unfeasible. To avoid an isolation system design based on a compromise among its conflicting requirements, a degree of real-time, on-demand adjustability should be built into the mounting system. Air springs/mounts, because of their inherent adjustability, are the best candidate for such adjustable isolation; other passive mounts, e.g. elastomeric, would require the introduction of an additional active element/actuator to work in parallel with the mount. In this proposed adjustable air mounting system, shock isolation can be enhanced without undermining the vibration isolation effectiveness by using an on-demand, active damping scheme which adds various levels of damping to an air mounted/suspension application, e.g., the cab in a truck, depending on the instantaneous urgency of shock isolation over vibration isolation. In addition, the proposed adjustable isolation scheme contains an on-demand, active stiffness control working in parallel with the active damping scheme. Depending on the operating conditions, the stiffness of the mount will be lowered to better its vibration isolation or increased to enhance its shock isolation. The active damping and stiffness control along with other on-demand adjustment tactics for an air isolation system are described, numerically examined, and experimentally demonstrated.
Potential Vibration Isolation Qualities of Suspensions with a Two-Step Stiffness Control in Oscillation Cycle
