Diesel CB18 High Pressure Pump Diagnosis Based On Fuzzy Theory

With CNIV emission standard implementation,the demand of CR system for commercial vehicle market significantly increases,meanwhile the maintenance and diagnosis stress of CR system are also increasing.For low cost and rapid diagnosis of CR is the development direction for the market.In this paper,CB18 as a new generation of CR pump whose structure is described in detail,and the failure mode of CB18 has been carried on with analysis and classification that failure reasons are most concentrated in the HPA,OFV,Mprop and VP.How to quickly determine the four types of components of fault failure is the key of the research,through the test bench to simulate start working condition and load conditions of the pump and extract the corresponding waveform,after selecting the high pressure and low pressure waveform corresponding 5 characteristic parameters such as maximum pressure amplitude in high pressure output,pressure rise width in output waveform,high pressure output waveform continue width,maximum pressure amplitude in low pressure waveform and pressure amplitude mean square error.Difference analysis has been implemented via comparison between standard mode pressure waves and failure mode pressure waves afterwards,then,it has been found out that the way to judge the failure of all key components by characteristic parameters is feasible and effective.Finally,the fault pump bench test is operated and the failure modes of CB18 are clearly identified by the method of maximum membership degree classification with fuzzy theory and hamming distance.The research significance of this paper is to determine the wave of fault pump via fuzzy recognition in order to locate the fault components w/o pump disassembly,to shorten the time of diagnosis effectively,to reduce the maintenance cost significantly by changing the failure components only,to play the guiding role when the automatic diagnosis equipment will be developed based on fuzzy pattern recognition.