Dynamic Measurement Of Valve Train System And Analysis Of Vibration Under The Operation State Of Diesel Engine

The valve train system is an important part of the diesel engine,which controls the ventilation process of the engine,and whether its design is reasonable will directly determine the power,economy,reliability,emission level and vibration noise level of the diesel engine,which plays a vital role in the comprehensive performance of the diesel engine.Through the dynamic test of valve train system,we can study the kinematics,dynamics,vibration noise and other related characteristics of valve train system,so as to provide important data support and experimental basis for the optimal design of valve train system,as well as the dynamics of valve train system and the theoretical research of damping and noise reduction,so it has important theoretical significance and engineering practice value.At present,most of the dynamic research of valve train system stays at the stage of bench experiment and numerical simulation,and it is less possible to realize the dynamic on-line measurement of valve train system under the actual operation State of diesel engine,the processing and data representation methods of related dynamic characteristic parameters are not systematic,at the same time,The analysis of valve vibration and other related research is also rarely published in literature.Under the actual operation State of diesel engine,the dynamic characteristics of the valve train system are affected by thermal expansion and other components of diesel engine,so that the dynamic characteristics of the valve train system obtained by the simulation test bench can not fully reflect the dynamic reality of the valve train system under the actual operation State of the diesel engine.Taking a single-cylinder marine diesel engine as the research object,this paper carries out an on-line measurement of the dynamic characteristics of the valve train system under the actual operation State of the engine,and obtains the dynamic characteristics of the valve train system of the engine by measuring it.The kinematics state,dynamic state,and vibration state of the valve train system under the actual operation State of the engine are analyzed and studied by means of the relevant data processing method.Firstly,this paper designs a set of on-line measurement system of valve train system dynamics,through the laser displacement sensor,eddy current displacement sensor,piezoelectric acceleration sensor,metal strain gauge and other sensors and related installation tooling,realizes the on-line measurement of the dynamic parameters of a highpower marine diesel engine valve train system,and specifically measures the valve lift,dynamic parameters such as valve clearance,valve acceleration and valve train system strain.Then,according to the characteristics of each dynamic measurement data of the valve train system,the experimental data processing methods such as data filtering,digital filtering,cyclic averaging,frequency domain analysis and data fusion of the experimental data are completed.Through the appropriate data processing methods,as well as the relevant representation methods and evaluation indicators,the data processing of various measurement data is carried out,the kinematics and dynamics characteristics of the accurate valve train system are obtained,and the valve flight,valve reverse jump and the stress of the valve train system of the valve train system are analyzed in detail.Finally,the analytical study of valve vibration is carried out,and the specific source and corresponding composition of valve vibration are analyzed concretely.In the process of analysis,the advantages and disadvantages of various statistical methods(empirical modal decomposition EMD)and multiple time-frequency joint analysis methods(short-time Fourier transform STFT,continuous wavelet transform CWT)are compared and studied.The continuous wavelet transform CWT with the best analytic effect is used to decompose the acceleration data of the exhaust gate with the propulsion characteristic 100% load condition,and the composition signal of the valve acceleration is analyzed in detail.The experimental method of experimental verification of the analytic results is put forward.