基于声发射和小波分析的活塞环-缸套系统的摩擦润滑状态研究

Using acoustic emission (AE) technology on-line monitoring of friction lubrication status. The wavelet multi-resolution analysis technique is used to suppress the large amplitude acoustic emission AE signal caused by the valve switching and combustion oscillation, and the acoustic emission signal caused by viscous friction is extracted by the threshold noise reduction method. Then use the wavelet envelope analysis to calculate the average value of the amplitude of the acoustic emission signal in the middle of the stroke as an index to evaluate the lubrication state of the piston ring-cylinder liner system. The test results show that the acoustic emission signal in the middle of the stroke can effectively characterize the frictional lubrication state of the piston ring-cylinder liner, and can distinguish the effect of different types of oil on the lubrication status of the system through the acoustic emission indication standard. Among them, the amplitude of the acoustic emission signal increases slightly with the increase of the load, and increases with the increase of the rotational speed. The research results fully prove the effectiveness of acoustic emission monitoring technology in the on-line monitoring of the friction lubrication state of the piston ring-cylinder liner.

利用声发射(AE)技术对摩擦润滑状态进行在线监测。采用小波多分辨率分析技术抑制由阀门开关和燃烧震荡引起的大幅值声发射AE信号,并采用阈值降噪的方法提取出由粘滞摩擦力引起的声发射信号。然后运用小波包络分析计算冲程中部的声发射信号幅值的平均值作为评价活塞环-缸套系统润滑状态的指标。试验结果显示:冲程中部的声发射信号能够有效地表征活塞环-缸套的摩擦润滑状态,并能够通过声发射指示标准区分不同类型的油品对系统润滑状态的影响。其中,声发射信号的幅值随着载荷的增大而小幅增大,且随着转速的增大而明显增大。研究结果充分证明了声发射监测技术在活塞环-缸套摩擦润滑状态在线监测的有效性。