Ignition Intensity Measurement And Ignition Equilibrium Analysis Of Magneto Based On Ultraviolet Detecting

Aviation magneto ignition system failure is a frequently occurred and dominant problem, which accounts for more than 2/3 of the total aviation piston engine failure. However, the method used for this failure diagnosis is simply depended on the visual inspections in the civil aviation maintenance field. Due to human factors, the visual inspections can not provide ignition intensity value and ignition equilibrium deviation value among the different spark plugs in the different cylinder of aviation piston engine, and also can not provide quantitative standard for the magneto maintenance. Therefore, ignition intensity measurement of aviation magneto ignition system is an urgent problem needed to be solved in the civil aviation maintenance field.The ultraviolet detecting technology is used to measure aviation magneto ignition intensity in this paper by comparing visual inspections, indirect voltage-current energy measurement, infrared detecting, and ultraviolet detecting. A 185-260nm wavelength, "solar-blind" ultraviolet sensor is selected as the key device in the ignition intensity measurement system. A hall sensor is used to measure rotate speed of aviation magneto. And a Data Acquisition (DAQ) card with 500Ksps sample rate is used to obtain output signals of the ultraviolet sensor and the hall sensor. In the software design, a virtual instrument is used to read, analyze and calculate the data acquired by the DAQ card. After the calculation, the virtual instrument displays and stores the results including the rotate speed and ignition intensity of each spark plug. The experimental results show that, the test error of the rotate speed is less than 0.34% at the rotate speed range of 0～3500 R.P.M. and the test error of the ignition intensity caused by data analysis is less than 0.13%.The test system measures the scanning full-speed range ignition intensity and the steady speed ignition intensity equilibrium of a normal magneto and another magneto waiting for maintenance in the field test. The results show that the inconspicuous and slight variation in distance between distributor rotor arm and distributor site causes 65 Pulse/Sec ignition intensity deviations. And the indistinguishable ignition intensity disequilibrium caused by high-voltage wire leakage can be detected directly in 200 Pulse/Sec. The test system can quantitatively measure the ignition intensity and ignition equilibrium and provides a quantitative diagnostic basis for the maintenance of aviation magneto ignition system in practice. Therefore, this technology fills the gaps in quantitative test for aviation magneto ignition systems diagnose. And it has a significant engineering application value.