针对内燃机噪声识别问题，建立了数学模型并编制了相应的程序，在程序中加入作用全局阈值的小波变换降噪程序，保证程序的抗干扰性后，实现了燃烧噪声和机械噪声的频谱分离和A计权声功率级计算。以某CG125型摩托车发动机为例，通过构造包含不同干扰噪声的理论算例仿真识别，验证了程序的准确性和实用性。识别结果表明：分离前后的燃烧噪声和机械噪声的频谱吻合良好，A计权声功率级误差均小于0.6 dB。

To identify internal combustion engine (IC engine) noise, a mathematical model is established, and the corresponding program is developed. By introducing global thresholds to decrease noise in the wavelet transforms program, the anti-interference of the program can be guaranteed, the spectrums of the combustion noise and mechanical noise are separated, and their A-weighted sound power levels are figured out. Taking a CG125 style motorcycle engine for an example, theoretical examples that include different interferential noises are constructed to simulate the identification and to validate the accuracy and practicability of the program. Results of the identification show that the spectrums of the combustion noise and mechanical noise before and after separation are agreed well; errors of A-weighted sound power level are all less than 0.6 dB.

重庆市自然科学基金资助项目(CSTC 2006 BA7013)