基于小波包分解的发动机机体振动信号影响规律

董一鸣¹，胡玉平^1*，田小青²，李萌³，纪少波^1,4

1.山东大学核科学与能源动力学院，山东 济南  250061；2.滨州职业学院，山东 滨州  256603；

3.山东省交通科学研究院，山东 济南  250102；4.上海交通大学动力机械与工程教育部重点实验室，上海  200240

摘要：为了探明柴油机机体振动信号的频谱特性，利用试验方法及信号分析技术，改变柴油机转速、转矩、机油温度等运行状态参数和配缸间隙，实测缸内燃烧压力及机体振动加速度信号；通过小波包分解方法将机体振动加速度信号分解为16频段，得到各频带的能量，与缸内燃烧压力信号进行对比分析，研究不同因素作用下，小波包各频带能量的变化规律，确定对燃烧状态及活塞敲击状态敏感的频段。结果表明：随转速升高，活塞往复惯性力增大，当转速由1 000 r/min增大到1 600 r/min时，频段16能量增大3.55倍；随转矩增大，各频段的能量都呈增加的趋势；随机油温度升高，多数频段能量变化趋势不明显，但15、16频段的能量仍呈增加趋势；随配缸间隙增大，频段6、7、8、10、15、16的能量显著增加。

关键词：机体振动信号；小波包分解；运行工况；配缸间隙

The influence laws of block vibration signal based on wavelet packet decomposition

DONG Yiming¹, HU Yuping^1*, TIAN Xiaoqing², LI Meng³, JI Shaobo^1,4

1.School of Nuclear Science, Energy and Power Engineering, Shandong University, Jinan 250061, China;

2. Binzhou Vocational College, Binzhou 256603, China; 3. Shandong Transportation Research Institute, Jinan 250102, China;

4. Key Laboratory for Power Machinery and Engineering, Ministry of Education, Shanghai Jiao Tong University, Shanghai 200240, China

Abstract: To investigate the spectral characteristics of the vibration signals of a diesel engine block, the experimental method and signal analysis technology are used. By changing the operating state parameters such as diesel engine speed, torque and oil temperature and the cylinder clearance, the combustion pressure in the cylinder and the vibration acceleration signal of the body are measured. The vibration acceleration signals are decomposed into 16 frequency bands using wavelet packet decomposition (WPD), and the energy distribution of each band is compared with the cylinder pressure signals. The study identifies the variation patterns of wavelet packet energy distribution under different influencing factors and determines the frequency bands sensitive to combustion state and piston slap. The results indicate that: As engine speed increases, the reciprocating inertia force of the piston rises. When the speed increases from 1 000 r/min to 1 600 r/min, the energy of frequency band 16 increases by 3.55 times. With increasing torque, the energy of all frequency bands shows an upward trend. As oil temperature rises, most frequency bands exhibit no significant energy variation, but bands 15 and 16 still demonstrate an increasing trend. With larger piston-to-cylinder clearance, the energy of bands 6, 7, 8, 10, 15, and 16 increases significantly.

Keywords: engine block vibration signal; wavelet packet decomposition; operating condition; piston-liner clearance