基于接触分析的气缸盖/气缸套密封性能研究

Study Sealing Performance between Cylinder Head and Cylinder Liner Based on Contact Analysis

针对某160型柴油机的单体缸盖-气缸垫-气缸套密封系统,建立了装配体的有限元模型。采用接触分析法,研究了发动机功率提升前后,在预紧加爆压工况下原紧固螺栓对气缸垫密封性能的影响,并对气缸垫密封面的变形状态进行了弹塑性分析,对结构的密封性能进行了评价。结果表明,发动机功率提升后气缸垫发生了塑性屈服,但轴向应力仍均为负值(即压应力),轴向变形量亦均为负值(即压变形),说明提升功率后发动机工作过程中气缸垫仍然密封良好。较以往将气缸密封垫假设为弹性体相比,采用摩擦接触边界条件进行塑性有限元分析,更能体现缸盖与气缸垫接触面的真实应力与变形状态,因此接触分析法是研究缸盖/缸套密封结构的一种较佳途径。

Aiming at the gasket sealing system between single gines,an elastic and plastic finite element model of the assembly combined with pretension force, the effect of initial joint bolts on cylinder head and cylinder liner of type 160 diesel enparts was built. On the conditions of peak fire pressure sealing performance of cylinder gaskets was studied with contact analysis method before and after the updating of engine＇ s power. The plastic distortion stage of gasket was analyzed, and the sealing performance of this structure was appraised. Results show that there is plastic yield deformation in the cylinder gasket after engine＇ s power was raised,but axial stress and axial deformation is still negative value, which indicates that the sealing performance of cylinder gasket is in good condition after engine＇ s power rose. Compared with the analysis method supposed the gasket as elastic solid before, the plastic finite elements analysis method with friction contact boundary condition can represent the real stress and strain status between contact surfaces of cylinder head and gasket. Accordingly the contact analysis method is a better way to research on the sealing structure between cylinder head and cylinder liner.