Research On The Power Testing And Failure Diagnosis Of Engine Based On Virtual Instrument

The power testing and misfire failure diagnosis are both the emphases of engine testing and diagnosis technology. The existing power testing systems and testing methods can not meet the demand of internal engine testing in terms of efficiency, precise and cost. Meanwhile, there are also many disadvantages in the misfire failure diagnosis methods. So it is of great significance and practical value to research highly efficient and exact engine power testing system without disassembly.This research sets up a set of virtual engine testing system based on LabVIEW and carries out the experiment research using the 490BPG engine as the object. Moreover, it raises the new method that use the cylinder-top vibration signals to test the engine power which is based on the no-load power testing principle and adopts digital filter technology. Furthermore, it also researches the misfire failure diagnosis method with the Matlab wavelet tool box based on wavelet analysis theory. The main conclusions are as follows.1) This paper builds a set of engine testing system using LabVIEW virtual instrument. The system which consists of data acquiring system and power testing system can continuously acquire and store the rotate speed and vibration signals online in real time. Moreover, it can obtains the power-rotate speed performance curve and average power from rotate speed.2) In order to simplify the measurement process and to improve accuracy, it improves the engine no-load power testing method by decreasing the signal picking up period of rotate speed sensor and calculating the accelerating period with rotate speed.3) The engine power-rotate speed curve which obtained by the LabVIEW no-load power testing system, which adopts magnetoelectric rotate speed sensor, generally coincides with the engine exterior performance curve. The relative error of average power value is 1.94% compared the engine demarcated power value, So it meet the project applying accuracy.4) By digital filtering and spectrum analyzing the engine cylinder-top vibration signals obtained by the piezoelectricity accelerating speed sensor, it can be known that the engine rotate speed should obtained from the cylinder-top vibration signals. And after then it can obtain the engine power-rotate speed curve. The experiment shows that the...