发动机结构及参数对缸孔变形的影响

Influence of engine structure and parameters on bore distortion

以某无缸套柴油机为研究对象,建立机体-缸垫-缸盖一体化有限元计算模型,采用傅里叶变换研究发动机各结构参数对缸孔变形的影响。研究结果表明:减少机体上水孔和清砂孔数量,可以有效降低缸孔变形;机体设计时应控制上水孔和清砂孔的截面积尽可能小,且要尽量远离缸孔;螺栓的布置对缸孔变形有一定的影响,而且4颗螺栓对4阶缸孔变形最为敏感,设计时应使螺栓的跨距尽量均匀;在缸垫密封满足要求的情况下,可以通过降低最外侧2个缸的螺栓轴力来减小2阶缸孔变形;增大缸心距可以改善机体刚度分布,有效降低缸孔变形。

The cylinder block of a jacket-free diesel engine is studied,the thermo-mechanical coupling finite element model is established,and the influence of structural parameters to the bore distortion are studied by using Fourier series.It is found that reducing the number of upper water hole and sand hole can effectively reduce the bore distortion.The smaller sectional area of the hole and away from the hole,the less bore distortion.The arrangement of bolts has a certain influence on the bore distortion,especially the four bolts are the most sensitive to the fourth-order bore distortion.So the span of bolts should be considered as uniform as possible in the design.When the gasket seal meets the requirements,the bore distortion of the second order can be reduced by decreasing the bolt force on both sides of the cylinder.Improving the stiffness distribution by increasing the cylinder center distance can effectively reduce the bore distortion.