基于发动机质心广义力识别的故障诊断方法研究

At present most of the engine fault diagnosis are specific to a particular type of failure. The mapping relationship between features of analysis object and faults is not clear, thus the extracted features have poor universality, which leads to the slow development of engine fault diagnosis. So far, there is not a mature diagnosis system for practical application. The generalized force at the center of gravity of engine is considered to be a new analysis object for engine fault diagnosis. By theoretical analysis, the combination of the finite element and multi-body dynamics modeling and simulation and experimental study, the fault feature library is built. Thus the clear mapping relationship between the analysis object feature and the fault is achieved. Since the exact identification of the generalized force is the precondition for accuracy engine fault diagnosis, the interpolation method for discrete spectrum is deeply studied to improve the correction accuracy of harmonic signal corrupted by noise and the commonality of method. Then the improved interpolation method of discrete spectrum is applied to the engine generalized force identification. The engine elastic modal is carefully studied to decrease its affections on the identification of the generalized force. And the generalized force identification method is accurately confirmed by experiment.. Through the study of the project, the new engine fault diagnosis method will be proposed, and the accuracy generalized force at the center of gravity of engine identification method is achieved. Eventually, the complete test and analysis theory and method for engine vibration design and monitoring protection is developed.

目前发动机的故障诊断大多只针对某一特定类型的故障，且分析对象的特征与故障的映射关系不明确，提取的特征通用性不好，导致发动机故障诊断发展缓慢，没有一套成熟的诊断系统可进行实际应用。本课题拟将质心广义力作为汽车发动机故障诊断新的分析对象，通过理论分析、有限元与多体动力学联合建模、试验研究等方法建立发动机质心广义力故障特征库，实现发动机故障诊断分析对象的特征与故障的明确映射关系。提出离散频谱比值校正改进方法，并利用改进后的离散频谱比值校正方法提高发动机质心广义力的识别精度，消除或减小发动机弹性体模态对质心广义力识别精度的影响，实现发动机质心广义力的精确识别，并进行精确的试验验证，为质心广义力识别精度提供有力证据。. 通过课题的研究将为发动机故障诊断方法开辟新的途径，从理论上得出发动机质心广义力精确识别方法，形成发动机振动设计和监测维护一套完整的测试分析理论与方法。

研究了影响发动机质心广义力识别精度的影响因素，同时分析了该方法误差产生的原因，并提出了相应的避免措施，引入改进后的离散频谱比值校正法提高识别精度，对发动机质心广义力识别方法进行了试验验证，为质心广义力识别精度提供了证据。采用理论分析、有限元和多体动力学联合仿真建立了发动机仿真模型。通过大量仿真和实验提取了发动机失火、气门间隙过大、活塞敲缸、凸轮轴承脱落等典型故障质心广义力信号特征，建立了发动机质心广义力故障特征库，实现了利用发动机质心广义力进行故障诊断的方法。这些成果改善了发动机分析对象的特征与故障的映射关系不明确问题，故障特征通用性较好，对于完善发动机故障诊断方法具有重要的理论意义和实用价值。. 在国内外刊物一共发表论文3篇，SCI、EI共同收录国际杂志2篇，国内核心杂志1篇。申请并受理发明专利2件。