考虑非线性因素的燃烧室密封特性分析

Sealing Characteristics Analysis of Composition of Combustion Chamber System Considering Nonlinear Factors

以某V型高强化柴油机为研究对象，考虑气缸垫中基材的弹塑性变形特性、密封橡胶的超弹性特性及燃烧室各部件间的接触非线性因素，建立了燃烧室气缸垫密封特性有限元分析模型。借助有限元非线性求解方法，计算气缸垫密封凸纹和橡胶密封圈表面的接触压力，以此评价发动机动力强化后燃烧室的密封效果，同时探讨了气缸盖螺栓顸紧力与燃烧室密封特性的关联性，确定发动机动力强化后缸盖螺栓预紧力的优选范围。分析结果表明：强化后热一机耦合工况下，气缸垫密封凸纹上最小接触压力比强化前下降了13％，燃烧室密封效果降低；将缸盖螺栓预紧力控制在88～92kN范围内，可使燃烧室的密封性能达到强化前状态。

Based on aV type highly intensified diesel engine, the combustion chamber cylinder gasket sealing characteristics finite element model was established, considering the elastic-plastic deformation characteristics of cylinder gasket, the sealing rubber super elastic characteristics and the nonlinear contact factors between the components of the combustion chambers. With the help of the nonlinear finite element solution method, the contact pressures of the cylinder gasket sealing embossed surface and rubber sealing ring were calculated to evaluate the sealing effect of the combustion chamber for the intensified engine. Mean while, the correlation between the cylinder head bolt preload force and the combustion chamber sealing characteristics was studied to define the preload preferred range of cylinder head bolts for the intensified engine. The results demonstrate that the minimum contact pressure of the cylinder gasket sealing embossed surface is decreased by 13% under thermal-mechanical coupling conditions after intensification and the combustion chamber sealing effect is reduced than that before intensification. In order to improve the combustion chamber sealing performance, the cylinder head bolt preload force should be controlled within the range of 88～92 kN, that the combustion chamber sealing performance can reach the level before intensification.