蒙特卡洛法在共轨系统可靠性分析中的应用

Application of Monte Carlo method in reliability analysis for common rail injection system

为了在共轨系统自主研发过程中实现结构可靠性的量化分析,采用蒙特卡洛法对建立的1种"泄漏-限流"失效模型进行计算研究.此失效模型涉及共轨系统的限流器、循环喷油量、动态回油量以及控制活塞偶件和油嘴针阀偶件的余隙泄漏.模型中的变量参数取自试验检测统计值.将蒙特卡洛法的直接抽样法、重要抽样法的计算精度和应用可行性等进行了对比分析.结果表明:采用重要抽样法得到"泄漏-限流"失效率的计算结果为7.97×10-5;限流器临界值、油嘴针阀偶件工作间隙和控制活塞偶件工作间隙对此失效率的影响较大;油嘴针阀偶件工作间隙的标准差对此失效率的敏感性较大,约为控制活塞偶件对应量的3.1倍;蒙特卡洛重要抽样法适用于共轨系统的结构可靠性计算分析,此应用简便且有效.

To realize quantitative analysis of structural reliability in the process of common rail injection system（ CRS） development,a ″leakage-shutting″ failure model was established,and a structural reliability investigation was demonstrated based on Monte Carlo（ MC） method. The model related to the fuel delivery limitation in restrictor and the fuel distribution in common rail injector,and the latter included fuel injection,fuel dynamic leakage and fuel clearance leakage of command-piston matching parts and nozzle needle matching parts. The parameters of random variables in model were obtained by statistical result of product sampling test. The calculation precision and feasibility of MC direct sampling method were compared with those of MC important sampling method. The results show that the calculation result of failure rate is 7. 97 × 10- 5by MC important sampling method. The failure rate is mainly influenced by several variables of limitation value of restrictor and working clearances of the two pairs of matching parts.The failure rate sensitiveness to working clearance standard deviation of nozzle needle matching parts is3. 1 times than that of command-piston matching parts. MC important sampling method is appropriate for CRS reliability analysis.