Research On Fault Diagnosis And Health Assessment Of Injector In Common Rail System

Injector is the key component of common rail system,which is responsible for fuel injection,and has a deep impact on the performance of diesel engine.The operating environment of fuel injector is complex,it is easy to fault and cause economic loss.When the injector fails,the waveform and frequency of pressure signal will be changed.It can be seen that the pressure signal of common rail system is directly related to the working state of fuel injector,so the pressure signal has obvious advantages in fault diagnosis and health assessment of fuel injector.However,the components of pressure signal are complex.How to extract features from the components closely related to injector fault is the key to reduce the redundancy of feature information and improve the accuracy of fault diagnosis and health assessmentFirstly,a fault diagnosis method based on common rail pressure is proposed,which extracts the waveform features and wavelet energy features of common rail pressure signal,and combines the features with neural network to diagnose the fault location and type of injector.The results show that the method has high accuracy.Then,the condition assessment based on the inlet pressure of the injector is proposed.The water hammer pressure in the inlet pressure is related to the state,and the injection quantity is also related to the state.EMD decomposition and mutual information value calculation are used to extract the characteristics of water hammer pressure wave.A new eigenvector is constructed based on the injection quantity.The Euclidean distance of feature vector is calculated to get the performance degradation curve based on the fault degree.Finally,according to Weibull distribution and injector life,get the relationship between reliability and time,and the statistical results of injector reliability,get the relationship between reliability and health status,finally get the life prediction model of injector.In the research of fault diagnosis and health assessment of fuel injector,this paper not only realizes fault identification and fault location,but also obtains the current state of fuel injector and predicts its remaining life,which provides effective guidance for the maintenance of fuel injector.