柴油机加速振动信号的阶比双谱特征提取

针对发动机加速过程振动信号的非平稳性和混有大量噪声的特点，提出计算阶比跟踪和双谱相结合的方法，将振动信号按等角度间隔进行软件重采样，得到阶域内的平稳信号，再进行双谱分析，通过仿真信号验证了该方法优于传统双谱。为了充分利用阶比双谱图中的信息，提出双谱特征阶比面的概念，通过比较阶比平面内的累加能量来反映不同工况的变化。诊断实例表明，该方法能有效提取柴油机曲轴轴承的故障特征。

Feature extraction for accelerating vibration signal of a diesel engine based on order bi-spectrum estimation

For the non-stationary and color noise characteristics of accelerating vibration signal from diesel engine , a method based on computed order tracking (COT) and bi-spectrum is proposed. The unstable signal is re-sampled at constant angular interval and the stabilized signal is obtained at the order area, then to analyze by bi-spectrum method. The simulation shows that the order bi-spectrum analysis is superior to the conventional bi-spectrum. To utilize the information from order bi-spectrum results fully , the novel concept—bi-spectrum characteristic order plane is put forward . Different working conditions of engine can be reflected by comparing the accumulated energy within order plane. Experimental results indicate that this method can extract feature of accelerating vibration signal effectively.