Experimental Evaluation of the U-Shape Cranktrain through Engine Tests

Targeting the current demands for engines with lower emissions, reduced fuel consumption, downsizing and higher peak combustion pressures, thyssenkrupp has developed a new cranktrain concept comprising an increased radial transition between journal and web that extends itself into the bearing’s load-carrying zone, creating a symmetrical U-shaped profile. The resulting non-straight bearing contour restricts the use of a standard bearing shell and led to the development of an integral bearing solution, where a copper based material was applied directly to the connecting rod big end bore. The so-called U-shape cranktrain was experimentally evaluated on a fired engine through a series of eight test steps with varied loads and speeds, being each step condition defined in a way that increased severity was applied to the connecting rod bearings as the test proceeded. The engine was disassembled after each step for analysis and measurement of the crankshaft and connecting rods. This work will present the result of 130 hours of engine tests accumulated during the eight steps as well as the analysis of the generated data, which will be used for further development of the U-Shape design.