【作者】 刘鹏；

【导师】 司景萍；

【作者基本信息】 内蒙古工业大学 ， 动力机械及工程， 2006， 硕士

【摘要】 在发动机各种类型故障中与气门间隙异常相关的故障占了很大比例,所以针对此类型故障的诊断具有重要意义。本文以DA462型发动机为研究对象,对于基于振动分析的气门间隙异常故障诊断进行了分析和研究。在本论文中,以发动机结构及运转特性等分析为基础,确定了燃烧激励、活塞敲击激励、惯性力激励、气门落座冲击和气门开启节流冲击为发动机的主要激励源,并且分析了发动机振动的传播路径;结合本课题的研究内容,合理的选择了燃烧激励响应和排气门开闭激励响应作为故障特征信号;通过详细地研究振动信号分析方法,采用了时域分析和频域分析相结合的信号分析方法。在分析了现代振动测试技术的基础上,成功的搭建了一套实用的振动信号测试系统,通过实验,验证了该系统能够准确的获得故障特征信号。采用双排不进的气门间隙调整法将气门间隙调整为0.15mm、0.25mm、0.35mm和0.45mm,其中0.15mm为正常间隙,用其它的数值模拟气门间隙异常。通过本课题搭建的测试系统测得不同转速和不同间隙下的振动信号,总结出发动机转速对故障特征信号的影响情况,以及不同间隙对故障特征信号的影响程度;通过理论分析确定故障特征信号的频带,再观察这个频带随间隙调整的变化状况,这样通过对实测故障信号和正常信号的对比分析,提出了一种行之有效的内燃机故障诊断方法。通过对DA462型发动机的实验验证,证明了本课题提出的基于振动分析的气门间隙异常的故障诊断方法,具有简单、准确和实用性强的特点。更多还原

【Abstract】 Abnormal fault of Internal Combustion Engine valves clearance have the very big percent in various type of Internal Combustion Engine faults, so it has important meaning to make diagnosis of this kind fault. This paper take the DA 462 type engine as research object, putting forward diagnosis method based on vibration analysis according to abnormal state of valves clearance.In this paper, author take analysis such as the Internal Combustion Engine structure and the operation characteristic as the foundation, making sure that the combustion excitation ,the piston slap excitation, the inertia force encourage, the valve falling impact and throttle impact when valve opens act as main excitation source, and analyze the propagation path of engine vibration. Combining this subject study, choose response of the combustion excitation and exhaust valve excitation as fault characteristic signal. Through studying the method of analyzing vibration signal in details, adopt the method of signal analysis combining the time domain analysis together with the frequency domain analysis. Basing on the analysis of modern vibrate measuring and testing techniques, built a set of practical vibration signal measuring and testing system successfully. Through the experiment, verify that this system can get fault characteristic signal accurately. Adopt the method of“shuang pai bu jin”to adjust the valve clearance data which are 0.15 mm,0.25 mm,0.35 mm and 0.45 mm. Among those data, normal clearance is 0.15mm, using the other data to simulate abnormal state of valve clearance. Using the measuring and testing system that was built for my subject, we can get the vibration signal in condition of different rotation speed and valve clearance, making conclusion that different rotation speed and valve clearance influence on the degree of the characteristic signal. The frequency band of the fault characteristic signal through the theories analysis is taken certainly, in next step observing range of frequency band’s variation when we adjust clearance data, then we can judge the size of the valve clearance in the light of time domain and frequency domain’s wave figure of fault characteristic signal .更多还原