张伟龙1,2，邬忠永1,2，丁保安1,2，郭彬1,2，李秀山1,2
（1.内燃机可靠性国家重点实验室，山东 潍坊 261061；2.潍柴动力股份有限公司，山东
潍坊 261061）
摘要：为了改进汽车的振动和噪声性能，针对某牵引车在中高转速段内噪声大的现象，对薄壁件噪声产生机理和特性进行分析，提出了解决问题的诊断思路。通过NVH试验及LMS Test.lab声诊断方法，确定噪声源主要为隔热罩辐射噪声，表现为多个频率下的窄频噪声，隔热罩存在某固有频率下共振和结构阻尼太小导致受到激励时辐射噪声较大。通过改变隔热罩材料和优化结构阻尼减少隔热罩辐射噪声，经过试验验证，整车噪声中隔热罩辐射噪声降低7~8 dB(A)，噪声贡献率由62.7%降低为20.2%，优化后整车噪声降低3~4dB（A），不仅降低了噪声值，而且提升了声品质。
关键词： Test.lab；隔热罩；辐射噪声；NVH
Abstract: To improve the vibration and the noise performance of vehicle,
for example, the high noise in the middle and high speed of certain tractor,
the mechanism and characteristics of thin - walled parts noise are analyzed,
this paper presents a diagnosis method to solve this problem. Through NVH Test
and acoustic diagnostic method of the LMS Test.lab, determines that the noise
source is mainly the radiation noise of heat shield. It manifests as narrow
frequency noise in multiple frequency. The radiation noise is greater when
stimulated, the main reason is that the heat shield has the resonance of an
inherent frequency and structure damping is too small. By changing the heat
shield material and optimizing the structural damping to reduce the radiation
noise of the heat shield, the test verified that the radiation noise of heat
shield is reduced by 7~8 dB(A) for vehicle noise contribution and The noise
contribution rate was decreased from 62.7% to 20.2%. After optimization, the
vehicle noise is reduced by 3~4dB (A),It not only reduced noise value, but also
improved sound quality.
Key words: test.lab;heat shield;radiation noise;NVH
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