Single Pumper Semi-Active Fluid Mount

Abstract

Passive fluid mounts have been in use in the automotive and aerospace applications for the purpose of cabin noise and vibration reduction since 1940s. Cabin noise and vibration isolation is provided at a frequency coined “notch frequency”. The design location of the notch frequency depends on the application, but with most applications, it is designed to coincide with the longest period of constant speed. To obtain greater cabin noise and vibration reduction at any desired frequency, the notch frequency needs to be as close to that desired frequency as possible. Unfortunately, due to tolerances on all the fluid mount dimensions, material property variations, and variation in elastomer molding processes, the notch frequency never ends up at the right location on the first manufacturing pass. Since none of the passive fluid mount parameters are controllable, the only way to tune the mount is to redesign the mount by changing fluid, changing inertia track length or diameter, or changing rubber stiffness. This trial and error manufacturing process is very costly. To reduce the fluid mount notch frequency tuning cycle time, a new fluid mount design is proposed. In this paper, the new design concept, and its mathematical model and simulation results will be presented.