Multi-objective Optimization Research On Operating Performance Of Piston Assembly

The optimization of engine NVH is very important in enhancing the comfort of automobiles. Piston is one of the most important moving parts in engine. Current research shows that piston performance not only has a great impact on dynamic performance, fuel economy and emission performance, but also plays an important role in engine NVH performance. Therefore, to study piston dynamics and optimize its performance has essential meaning. This paper studied piston assembly components for research. Piston and rings dynamics model was established, and remarkable results were achieved in the research of piston secondary motion, blow-by, oil consumption and piston slap.The numerical analysis model of piston secondary motion was established. Based on dynamic model of piston and rod, finite element model and lubrication model, simulation analysis of piston was researched comprehensively. The secondary motion, contact force, kinetic energy and friction loss were analyzed. Based on this analysis, structure of piston was optimized and the optimization design improved the motion of piston effectively.The working state of piston rings was researched. Piston ring numerical analysis model was established. This model consisted of dynamic model, gas flow model, lubrication model and oil consumption model. Taking ring motion, lubrication, blow-by and oil consumption as targets, detailed analysis was carried out.Based on piston ring dynamic model, multi-objective orthogonal design and comprehensive evaluation method, the effects of ring end gap structural parameters on blow-by and oil consumption were detailed analyzed. Then structural parameters of piston ring end gap were optimized and remarkable results were achieved in controlling blow-by and oil consumption.By loading piston slap force on finite element model of engine, piston slap model was established. Analysis about engine block vibration caused by piston slap was carried out. Then the accuracy of the finite element model was verified by free model test, and the reliability of piston slap model was verified by motoring test. Finally, the impact of cylinder radial clearance on engine block vibration was analyzed and current plan was evaluated..