Engine Noise Reduction by Using an Underplate

The skirt part of cylinder block is identified as the major noise source of an engine by vibration and acoustic intensity level measurement results.

In order to reduce the engine noise the underplate which was installed under oil pan rail to increase the stiffness of the skirt part was analyzed by Finite Element Analysis (FEA) and designed accordingly. The modal model of the cylinder block was obtained using Experimental Modal Analysis (EMA) method. The modal models of both substructure were assembled into a single modal model and it was used to determine the dynamic characteristics using a system analysis software.

Finally the underplate of optimal design was machined to a prototype which was later subjected under the validation test. Sound pressure level of the engine with the underplate at operation condition was reduced.