| Since the diesel locomotive is the major traction power for the railway transportation in the altitude and western China as well as the important national strategic reserve resource, the development of engine which is the traction power of locomotive is absolutely critical. As one of the key moving parts of the engine, piston is the heart of the engine and its reliability and lifetime directly decide engine? reliability and lifetime.The thesis analyzes the technical status of medium speed locomotive engine at home and abroad and the development trendy of piston. The mature and reliable steel crown and aluminum skirt piston is used for detailed design and 3D model is built. 3D piston calculation analysis model is built and the boundary conditions and fixation load is added by the theoretic study of 3D piston limit temperature distribution and stress field. The temperature field distribution is analyzed. Stress distribution and deformation is also analyzed under the assembly load, gas load and inertia load. Fatigue performance for the piston under the normal temperature and high temperature is studied. And the static and dynamic safety factor of the piston top, inner cooling side, ring groove and piston pin bore is evaluated by Smith diagram. The optimization proposal of the R12V280 ZJ type of diesel engine piston is raised by the 3D FEA calculation and fatigue lifetime evaluation.The optimized piston is conducted with temperature field measurement analysis and the real thermal load condition is mastered and the correctness of the temperature field calculation is verified and the analysis model is corrected. The piston together with the engine has passed the UIC test, reliability test, thermal impact test, over speed and overload test and got the good result and without any crack or severe wear. The successful development of the R12V280 ZJ type of diesel engine piston has provided the theoretic and test base and good reference for the similar type of the product. |
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