Floating Clamping Mechanism of PT Fuel Injector and Its Dynamic Characteristics Analysis

• Published in: Chinese journal of mechanical engineering 2012-05, Vol.25 (3), p.550-556
• Main Authors: Wang, Xinqing, Liang, Sheng, Xia, Tian, Wang, Dong, Qian, Shuhua
• Format: Article
• Language: English
• Subjects: Clamping; Decomposition; Diesel engines; Dynamic characteristics; Electrical Machines and Networks; Electronics and Microelectronics; Empirical analysis; Engineering; Engineering Thermodynamics; Floating structures; Forced vibration; Free vibration; Frequency domain analysis; Fuel injection; Heat and Mass Transfer; Hilbert transformation; Hilbert谱; Hydraulic equipment; Hydraulic shock; Injectors; Instrumentation; Machines; Machining; Manufacturing; Mechanical Engineering; Power Electronics; Processes; PT喷油器; Signal processing; Theoretical and Applied Mechanics; Time domain analysis; Variations; Vibration analysis; 动态特性分析; 压力信号; 时频域分析; 浮动夹紧机构; 经验模式分解; 自由振动
• ISSN: 1000-9345; 2192-8258
• DOI: 10.3901/CJME.2012.03.550

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.