Abstract
PT fuel injector is one of the most important parts of modern diesel engine. To satisfy the requirements of the rapid and accurate test of PT fuel injector, the self-adaptive floating clamping mechanism was developed and used in the relevant bench. Its dynamic characteristics directly influence the test efficiency and accuracy. However, due to its special structure and complex oil pressure signal, related documents for evaluating dynamic characteristics of this mechanism are lack and some dynamic characteristics of this mechanism can’t be extracted and recognized effectively by traditional methods. Aiming at the problem above-mentioned, a new method based on Hilbert-Huang transform (HHT) is presented. Firstly, combining with the actual working process, the dynamic liquid pressure signal of the mechanism is acquired. By analyzing the pressure fluctuation during the whole working process in time domain, oil leakage and hydraulic shock in the clamping chamber are discovered. Secondly, owing to the nonlinearity and nonstationarity of pressure signal, empirical mode decomposition is used, and the signal is decomposed and reconstructed into forced vibration, free vibration and noise. By analyzing forced vibration in the time domain, machining error and installation error of cam are revealed. Finally, free vibration component is analyzed in time-frequency domain with HHT, the traits of free vibration in the time-frequency domain are revealed. Compared with traditional methods, Hilbert spectrum has higher time-frequency resolutions and higher credibility. The improved mechanism based on the above analyses can guarantee the test accuracy of injector injection. This new method based on the analyses of the pressure signal and combined with HHT can provide scientific basis for evaluation, design improvement of the mechanism, and give references for dynamic characteristics analysis of the hydraulic system in the interrelated fields.
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WANG Xinqing, born in 1963, is currently a professor at University of Science & Technology of Chinese People’s Liberation Army, China. He received his PhD degree from Tianjin University, China, in 1998. His research interests include mechanical-electronic engineering, fault diagnosis and signal processing.
LIANG Sheng, born in 1986, is currently a PhD candidate at University of Science & Technology of Chinese People’s Liberation Army, China. He received his bachelor degree from University of Science & Technology of Chinese People’s Liberation Arm, China, in 2006. His research interests include condition monition and fault diagnosis of the hydraulic system.
XIA Tian, born in 1983, is currently an engineer at Bureau of Navy Engineering Design & Research, China. He received his PhD degree from University of Science & Technology of Chinese People’s Liberation Army, China, in 2010. His research interests include machine design and signal processing.
WANG Dong, born in 1985, is currently a PhD candidate at University of Science & Technology of Chinese People’s Liberation Army, China. e]dyhkxywangdong@163.com
QIAN Shuhua, born in 1964, is currently an engineer at University of Science & Technology of Chinese People’s Liberation Army, China. She received her master degree from University of Science & Technology of Chinese People’s Liberation Army, China, in 2003. Her research interests include automatic control and computer measurement.
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Wang, X., Liang, S., Xia, T. et al. Floating clamping mechanism of PT fuel injector and its dynamic characteristics analysis. Chin. J. Mech. Eng. 25, 550–556 (2012). https://doi.org/10.3901/CJME.2012.03.550
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DOI: https://doi.org/10.3901/CJME.2012.03.550