Abstract: The most effective way for powerplant-mounting system to obtain excellent vibration isolation performance is to uncouple the multi-degree-of-freedom vibrations as much as possible. Based on the discussion of three uncoupling schemes for powerplant-mounting system under three different coordinates, I.e., crankshaft coordinate, torque-roll-axis coordinate and principal-mass-moment-of-inertia coordinate, the elastic uncoupling characteristics of the system are analyzed, and the best elastically uncoupling performance of the system with V-formed mounting pairs at the front and rear ends of the powerplant is predicted, which is that only two nonzero coupling stiffness are left. Then the lower limit for the principal stiffness ratio and the range of possible V-angle of V-formed mounting pair are revealed for elastic uncoupling between lateral and roll directions. Thus the design method for V-formed mounting pairs is further perfected. The concepts and methods presented here for design of elastically uncoupling mounting systems represent a significant progress in powerplant vibration isolation theory.

Key words: Automobile, Mounting system, Powerplant, Vibration uncoupling