Automotive Powerplant Isolation Strategies

Recently an increase in interest has occurred in automotive powerplant mounting. Evidence of this growth is the increase in the number of publications on the topic. The majority of this renewed interest has come from predicting and understanding the response of hydraulic engine mounts and the application of optimization techniques to the problem of powertrain vibration isolation, and occasionally to the combination of these two topics. However, it appears that these analytical techniques have been sufficiently developed and correlated to actual powertrain systems to have found widespread use by the automotive manufacturers. Subject to timing and packaging constraints, the more traditional mounting system design strategies are typically utilized. These strategies include natural frequency placement, torque axis mounting and elastic axis mounting. This paper presents a comprehensive review of these three strategies including a discussion of the assumptions associated with each method. In addition, the center of percussion mounting strategy, applicable to the isolation of transient inputs to the powertrain, is discussed in detail, including the technical basis for the theory.