关键件加工精度对EGR提升阀密封性的影响

Effect of Machining Accuracy to Key Part on Leakage of EGR Poppet Valve

EGR阀的阀片密封性对发动机性能的动态响应有重要的影响。密封性不合格不仅影响发动机的动力性,而且会恶化发动机的排放。阀的关键零部件的加工对其密封性起重要作用。就阀杆、阀片、阀座的重要加工尺寸进行分析,讨论了其各自对密封性的影响以及对密封性的综合评价。结果显示,阀杆的圆柱度精度较高,对密封性影响较小,阀片的内孔径公差较大对密封影响较大,阀座与阀杆的同心度容易出现偏差,需要与阀片焊接后与阀杆的同轴度相匹配才能得到良好的密封;综合这几个因素,需要提高阀座的加工精度,采用机加工的阀片,可以大大提高阀片的密封性。

There is a big influence of leakage about EGR valve poppet on the dynamic response of engine performance. Bad leakage not only affects engine performance, but also worsens engine emissions. The machining process of key parts of the valve plays an important role in leakage. In this paper, the important machining dimensions of stem, valve and seat are analyzed, the influence of their respective leakage and the comprehensive evaluation are discussed. Results show that, the cylindricity of the valve stem gives a higher accuracy so has a smaller effect on leakage. Big tolerance of valve plates inner diameter gives a greater influence on the leakage, the concentricity of valve seat and valve stem has a big chance giving big tolerance, so needs to match the concentricity after welding the poppet and valve stem. In combination with these factors, it is necessary to improve the machining accuracy of the seat and use machined valve poppet to improve the sealing greatly.