基于六西格玛的发动机性能一致性控制

Consistency control of engine performance based on six sigma

为提高发动机性能一致性,以某4缸涡轮增压的汽油机为研究对象,研究发动机概念设计阶段的发动机性能六西格玛设计和批量生产阶段的发动机性能散差六西格玛流程改进,识别和控制影响发动机生产一致性的关键要素。在概念设计阶段,应用Boost软件建立一维仿真模型,确定控制因子及水平,对气道进行稳健性设计,对压缩比进行容差分析,确保优化方案实现发动机设计目标;在产品量产阶段,识别出曲轴正时偏差和发动机功率修正系数不匹配是导致影响发动机性能一致性较差的原因。采取将飞轮螺栓孔、龙门支架传感器孔位置度均降至±0.15,及优化发动机功率修正系数等改进措施,并对改进前的发动机进行试验对比验证。试验结果表明,改进措施可使80%的发动机样机性能散差控制在±2%内。

In order to improve the engine performance consistency,this paper takes the power development and performance consistency control of a turbocharged engine as the research object,and studies the application of design for six sigma in engine conceptual design and six sigma process improvement in production consistency control.In the conceptual design phase,Boost software is used to establish a one-dimensional simulation model,determine control factors and levels,perform robustness design on the airway,and perform tolerance analysis on the compression ratio to ensure that the optimization scheme meets the engine design goals;During the mass production stage of the product,it is identified that the crankshaft timing deviation and the inapplicability of the engine power correction coefficient is the reason that affected the poor consistency of engine performance.Improvement measures such as reducing the positional accuracy of flywheel bolt holes and gantry bracket sensor holes to±0.15,and optimizing the engine power correction coefficient have been taken.Experimental verification shows that the improvement measures can control the performance deviation of 80%of engine prototypes within±2%.