Valve Train Dynamic Experiment And Model Study

Air exchange process of I.C. engine is controled by valve train, which has great influnce on engine performance. Valve train dynamic experiment and models are widely used in valve train study. By now, there are some limitations in valve train dynamic study, such as dynamic experiment standard, data processing methods, dynamic models' computed result coherence with experimental result, and adaptability of dynamic models to revolution.Aim of this paper is to study valve train dynamic experiment and data processing methods, compare the computed results with experimental result, analyze the adaptability of dynamic models to revolution and the coherence of results.Firstly, valve train test system (VTTS) was built in this project, which can take both valve train dynamic experiment and reliability experiment. Valve train dynamic characteristic can be tested by this system, with engine speed, temperature, lubricating condition in control. Valve acceleration is taken by piezoelectricity acceleration sensor, and valve displacement by eddy current displacement sensor.Secondly, data processing methods used in valve train dynamic experiment are analyzed in details. Least square fit method is used to eliminate drifting sign from piezoelectricity acceleration sensor. Data average, digital filter and wavelet metods were used to processing valve dynamic data. It shows that:â–  Least square fit method is better than digital filter used in eliminate acceleration sensor excursion.â–  Valve acceleration data suit to be exponential average, and linear average method can be used to processing valve displacement data.â–  Multi sensor data fusion method was used to get valve velocity data. Two kinds of valve velocity data were got from valve acceleration integral and displacement differential. Signal character in different time-frequency dormain is got by discreted wavelet transform. Based on the difference of frequency response of two sensors, the valve velocity signals were weighted added and reconstructed by wavelet. As the result, valve velocity without abnormal alteration is got.