Cranktrain Design Optimized for Reducing Weight and Friction Supported by Coupled CAE Tools

The OEMs are currently being faced with a variety of contradictions in terms of market demands and governmental regulations, which force them to develop concepts that assure high fuel economy, low exhaust emissions and high specific power. Because mechanical losses can account for up to 10% of the fuel energy used, the key to achieving these specific customer/government demands is to enhance the mechanical performance of the engine by decreasing friction and through the development of lightweight engine parts. Reaching these goals requires that each of these components be checked carefully to ensure that the designs are fully optimized. Numerous studies have shown that further optimization of the cranktrain parts is still possible, especially for the crankshaft. Advanced calculation approaches are the only means to completely exploit the potential development of the crankshaft and to ensure the component layout is within design limits. The purpose of this study is to illustrate a calculation procedure that highlights the borderline design of crankshafts under the consideration of the optimization objectives. The results show that even a production crankshaft contains enough durability potential to optimize its friction and weight, while resulting in minimal or no changes to the cranktrain and engine block.