车用气门室罩盖噪音优化的参数化分析

Parametric Analysis of Noises Optimization for Vehicle Valve Cover

摘要: 为减小车用气门室罩盖振动噪音，本文通过联合声学波动方程、振动力学、有限元法，建立了罩盖振动噪音的声–固耦合有限元本构模型，用此模型进行了15组参数化对比实验，研究了罩盖的厚度、弹性模量、密度等参数变化对噪音的影响，发现：在本研究参数范围内，罩盖的噪音介于55~120 dB之间，其中3阶噪音最大；噪音具有厚度、模量、密度效应，即增加厚度、弹性模量可有效降低各阶噪音，而密度反之，且三种效应均具有初期较强但后期逐步弱化的总体趋势；厚度1.5~2.5 mm、模量5000~9000 MPa、密度1.0~2.5 × 10⁻⁹ t/mm³区间能以较高效率将噪音降至80 dB以下，是此罩盖较为理想的噪音优化参数区间。

Abstract: In order to decrease vibration noises of vehicle valve cover, a coupled acoustics-structural FEM constitutive model for vibration noises of valve cover is developed by combining acoustic wave equation, mechanics of vibration, and FEM. The influence of parameter variation from thickness, Young’s modulus, and density of valve cover on noises is studied after 15 sets of parametric comparative experiments are carried out by this proposed model. It reveals that noises of valve cover are between 55 and 120 dB in the parameter zone of this research. The third order noise is maximal among the previous 5 order noises. There are effects of thickness, Young’s modulus, and density of valve cover on noises. Specifically, all order noises are descending efficiently with the ascending of thickness, Young’s modulus, but opposite completely for density cases. Moreover, the general tendency for all three kinds of effect is more predominant in the initial stage, but degenerated then. A promising parameter optimization domain to reduce noises of valve cover more efficiently to 80 dB below is probed, i.e. 1.5 - 2.5 mm for thickness, 5000 - 9000 MPa for Young’s modulus, and 1.0~2.5 × 10⁻⁹ t/mm³ for density.