基于模态的发动机进气歧管结构布置与优化设计

Intake Manifold Structure Layout and Optimization Design based on Modal Analysis

某发动机为了满足更高的节油要求和排放要求,进气歧管材料由铝制改为复合塑料材质,并增加了EGR进气方式,歧管结构更改幅度较大,共提出3种设计优化方案(A、B和C方案)。发动机在高转速运行时,极易引起进气歧管共振,有导致歧管断裂的危险。为此,应用模态分析理论,对3种新结构塑料进气歧管方案的模态固有频率及歧管支架布置方案进行分析和比较。分析结果表明,只有方案C进气歧管+辅助支撑,其1阶模态固有频率为201 Hz,达到设计目标177 Hz要求。

In order to meet a better fuel economy and emissions requirements,the intake manifold material of an engine was changed from aluminum to composite plastic material,and the EGR intake mode was adopted,resulting in great change in the manifold design,so three optimized design schemes(A,B and C)were proposed.When engine runs at high speed,manifold resonance can easily be triggered,which is possible to cause manifold crack failure.Therefore,the analysis and comparison of the modal natural frequency of the three schemes and the layout schemes of manifold supports were carried out with the modal analysis theory.The results show that scheme C with manifold support has the first order modal natural frequency of201Hz9reaching the target of177Hz.