Search Results

With growing demands for better fuel economy and reduced carbon emissions there is a need for smaller and more fuel efficient engines. At the same time, to improve passenger comfort there are also demands placed on improved vehicle quietness [1]. A Homogeneous Charge Compression Ignition (HCCI) system or a higher compression ratio system can be used to obtain better fuel economy but the enhanced combustion rate causes an increase in engine vibration in the medium to high frequency range [2, 3]. To ensure vehicle quietness, this issue of structure-borne noise that is transmitted from the engine mounts to the body must be addressed. In this paper a simple anti-vibration active mount system is introduced that can significantly reduce structure-borne noise at medium to high frequencies. This is achieved by adding mass to the insulator which leads to resonance at lower frequencies, in order to obtain double anti-vibration performance.

There was concern that a variable compression ratio engine fitted with a multi-link mechanism might produce louder booming noise due to the inertial forces caused by the lateral swing of the links. Accordingly, a relational expression between the inherent characteristics of the links was found to counterbalance those forces. As a result, it was found that a multi-link VCR engine designed on the basis of this link concept showed lower levels of horizontal excitation forces similar to the reduction of vertical forces. This suggests that, even without any add-on devices like a balance shaft, the engine can achieve the same level of booming noise performance as conventional engines. In addition, this new link concept obtained as a result of this study is expected to be effective in reducing higher-order interior noise as well.