改进小波阈值函数降低发动机冷试噪声测试仿真

徐卓¹，王辉²，杨晓峰²，吴凡¹，闫伟^1*

1.山东大学能源与动力工程学院，山东 济南  250014;

2.潍柴动力股份有限公司，山东 潍坊  261061

摘要：为在发动机冷试测试过程中得到较为精准的传递信号，在分析总结小波降噪的文献资料基础上，构造一种对发动机冷试测试过程中的故障诊断信号进行降噪处理的改进小波阈值函数，使用MATLAB进行降噪模拟仿真对比分析，并对冷试的柴油机缸盖高速振动信号加噪后进行仿真验证。结果表明：本文中提出的基于改进小波阈值函数的降噪方法效果较好；MATLAB仿真试验中，经改进的小波阈值函数处理后的信号信噪比为26.941 3，均方根误差为0.525 8；在柴油机降噪仿真试验中，经改进的小波阈值函数处理后的信号信噪比为3.086 8，均方根误差为2.288 1。改进小波阈值函数降噪方法对柴油机冷试振动信号具有较好的降噪效果。

关键词：小波降噪；阈值函数；冷试测试；故障诊断；发动机

Simulation of reducing signal noise of engine cold test based on improved wavelet threshold function

XU Zhuo¹, WANG Hui², YANG Xiaofeng², WU Fan¹, YAN Wei^1*

1.School of Energy and Power Engineering, Shandong University, Jinan 250014, China;

2.Weichai Power Co., Ltd., Weifang 261061, China

Abstract：In order to obtain a more accurate signal transmission in the process of engine cold test, this paper proposes a wavelet improved threshold function to reduce the noise of fault diagnosis signals in the process of engine cold test on the basis of analyzing and summarizing the literature of wavelet noise reduction, and uses MATLAB to simulate and compare the noise reduction, and selects the high-speed cylinder head vibration signal noise of diesel engine cold test for simulation verification. The results show that the noise reduction method based on wavelet improved threshold function performs quite well. In the MATLAB simulation test, the signal-to-noise ratio of the improved threshold function is 26.941 3 and the root mean square error is 0.525 8, and in the diesel engine noise reduction simulation test, the signal-to-noise ratio of the improved threshold function is 3.086 8 and the root mean square error is 2.288 1. This noise reduction method has a better effect on the cold test vibration signal of diesel engine.

Keywords: wavelet noise reduction; threshold function; cold test; fault diagnosis; engine