【作者】 孙少军；

【导师】 舒歌群；

【作者基本信息】 天津大学 ， 动力机械及工程， 2008， 博士

【摘要】 本文以重型车用发动机的振动和噪声问题为出发点,应用现代设计理论与方法对某直列四冲程六缸柴油机开展振动与噪声控制问题的理论和应用研究工作。采用理论与实验相结合的方法对内燃机表面振动与辐射噪声之间的关系进行了详细的研究,发展了表面振动速度法,得出了切合工程实际的通过表面振动预测发动机主要辐射噪声源对整机噪声声功率的贡献度和整机噪声声功率的定量关系表达式。对该柴油机的主要辐射噪声源及其对整机噪声声功率的贡献度以及整机的辐射噪声进行了预测,预测结果与实测结果基本吻合。采用声强测试方法对该柴油机进行了主要辐射噪声源的识别,并通过测试结果计算出了整机辐射噪声的声功率以及主要辐射噪声源对整机噪声声功率的贡献度,进一步明确了进行低噪声柴油机改进设计的目标。通过试验测试与分析的方法,研究了在不同的柴油机运行工况下,燃烧噪声及机械噪声对整机噪声声功率的贡献度,明确了在不同发动机转速与负荷下,燃烧噪声及机械噪声对整机噪声的贡献。将层次分析法和聚类分析法引入内燃机噪声源分析研究中,与试验相结合,创新性的分析研究了发动机工作转速范围内,噪声在1/3倍频程各中心频率下的贡献大小,各部件对重要频率段噪声贡献大小等,并定量给出权重指标值。采用实验模态分析与有限元分析相结合的方法对其结构动态特性进行了较为详细的研究,把握了该柴油机的振动特性和辐射噪声的主要原因,认识到了噪声能量主要集中于1/3倍频带中心频率为1000～2500 Hz的频带内。结合有限元和柔性多体动力学方法建立了该柴油机整机仿真模型,进行整机振动烈度和辐射噪声的模拟研究。分析了柴油机燃烧噪声、机械噪声产生的机理和影响因素,分别针对薄壳件的辐射噪声、燃烧噪声和机械噪声特点进行了有针对性的结构优化设计。在不增加柴油机生产工艺复杂性的基础上,最终取得了整机各测点振动下降2.0～8.8 m/s~2,辐射噪声额定工况A计权声压级平均降低2.5 ,怠速平均降低3.88的显著效果。更多还原

【Abstract】 Aiming at the problem of heavy duty vehicle engine vibration and noise, this thesis develops theoretical and application research on the vibration and noise control for a 6-cylinder, in-line, four-stroke diesel engine based on modern design theory and technique.Academic and testing method is used to research the connection between engine surface vibration and radiated noise. The surface vibration velocity testing method is developed to forecast the contribution of engine main radiated noise sources to engine whole sound power and engine sound power expression. The prediction of this diesel engine main noise sources and their contribution to engine sound power is carried out accords with experiment result. Sound intensity testing is done to identify engine main radiated noise sources. The contribution of engine sound power and noise sources are calculated from sound intensity test data. It shows the destination of low noise engine design.Contributions of combustion noise and mechanical noise to engine sound power on engine different operation condition are researched by testing. The influences of speed and load to contributions of combustion noise and mechanical noise to engine sound power are revealed. This paper also introduces analytic hierarchy process (AHP) and cluster analysis into engine noise source analysis. Based on test data, contributions and weight values of noise to 1/3 octave center frequency and engine main parts to key frequency band are analyzed in engine working speed range.Dynamic characteristics of engine block and crank shaft were obtained and investigated by experiment and FEA. The results from experiment and FEA revealed the reliability of the FEA model. The result shows the cause of engine vibration and surface radiated noise. Noise energy mainly focuses on 1000～2500 Hz in 1/3 octave band. Finite element method and flexible multi-body dynamics method are used to establish engine simulation model, calculate engine vibration intensity and radiated noise.Based on the investigation of diesel engine combustion noise and mechanical noise generation mechanismmain and influencing factors, the optimal designs are carried out to decrease engine radiated noise of thin-walled part, combustion noise and mechanical noise. Without adding complexity of engine production processing, the vibration of engine test points fall of 2.0～8.8 m/s~2 and engine sound pressure level fall of 2.5 dB ( A) on rating condition and 3.88 dB ( A) on idle condition.更多还原