SAE International A Study Concerning Booming Noise of a Multi-link Type Variable Compression Ratio Engine 2009-01-0772

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.