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Accurate powerplant inertia information is important for noise, vibration, and harshness (NVH) simulation and analysis of vehicle dynamics, both for engine mount systems in isolation and as part of vehicle system models. Because of the amount of effort involved in experimentally testing for the inertia properties of an automotive powerplant, typical practice is to test a single build variation of that powerplant. This inertia property information is then used to approximate the powerplant inertia properties of the other build conditions. This paper evaluates the effect of powerplant build options on powerplant inertia properties. An analytical approach is used, where powerplants are assembled analytically from a database of component inertia information, and the powerplant inertia properties determined. Powerplant inertia property results for a set of four cylinder, in-line powerplants, with different build options, are presented.

Serpentine belt system has been widely used during past years to drive automotive accessories like power steering, alternator, and A/C compressor from a crankshaft pulley. Instead of using multiple belt drives, the serpentine belt system uses a multi-rib flat belt, which wraps around several idlers and accessory pulleys. This design requires the use of a tensioning device to maintain adequate belt tension for preventing slip. Crankshaft torsional vibrations can lead to excessive rotational vibrations in poorly designed accessory systems. This can lead to undesirable noise and excessive slip, which can hamper the belt and bearing life. The value of these rotational frequencies and system response is of utmost interest to the accessory drive designer. While it is not practical to shift these rotational frequencies out of the operating range of an engine, a belt layout with these frequencies at non-dwell engine speed is highly desirable.