Basic research on the vibration and noise of internal combustion engines. (Vibration analysis and prediction of actual responses on the whole structure)

The purpose of the study described in this paper is to analyze and predict the vibration responses of an internal combustion engine (ICE). Firstly, all substructures of the ICE are modelled by the finite-element method, and their dynamic characteristics obtained by a component mode synthesis method (CMS) or by a multiple component mode synthesis method (MCMS) are checked by comparison with experimental results. Secondly, the dynamic characteristics of the whole system synthesized by MCMS are compared with experimental results to verify the accuracy of analytical results and the proprieties of the adopted connecting conditions. Thirdly, a computational prediction of the vibration characteristics, when the supplementary parts for reducing the vibration response level are added to the bottom of the cylinder block of the original engine, is carried out and also compared with experimental results. In addition, the overall level of the force at intake/outtake valve setting points is experimentally estimated in the frequency domain for the purpose of application as a factor of excitation forces in the engine during operation. Then, by using the FE model and the estimated valve-driving forces, the forced vibration analysis is carried out with MCMS. It is shown that the result corresponds well with the experimentally obtained results.