Design And Test Analysis Of Ultrasonic Dynamic Oil Film Thickness Testing Bench For Marine Diesel Engine Piston Ring

Diesel engine works in high temperature and high pressure environment for a long time,in which the piston assembly and cylinder wall are important friction pairs,the lubrication performance between them plays a key role in ensuring the reliability of diesel engine operation and prolonging the service life of diesel engine,etc.However,due to the complex operation of diesel engines,most of the research is limited to the theory and calibration of ultrasonic measurement technology,and there are few studies on the suitable diesel engine cylinder dynamic oil film thickness test bench and its practical application in dynamic measurement of diesel engines.Therefore,this article will oil film thickness between piston ring and cylinder wall as object of measurement,according to the ultrasonic detection method of oil film thickness in the piston ring dynamic oil film thickness in the application demand of test rig design and test analysis,to obtain a set of dynamic simulation of diesel engine piston ring oil film work environment of the oil film thickness ultrasonic test rig,Thus,the research on dynamic oil film thickness measurement of diesel engine piston ring by ultrasonic wave is promoted.Firstly,by deducing the relationship between oil film thickness and ultrasonic reflection coefficient,the direct representation forms of resonance model,spring model and phase shift model in their respective applicable oil film thickness range are obtained.And centering on the dynamic oil film thickness measurement environment of diesel engine piston ring and the application requirements of ultrasonic oil film thickness measurement technology,The appropriate measurement model is selected from the three to write the test data processing software and confirm the overall design scheme.Then,according to the application environment of oil film thickness ultrasonic measurement technology and the working characteristics of diesel engine cylinder and piston ring,the diesel engine piston ring dynamic oil film thickness ultrasonic testing platform are designed,and through analyzing the shortcomings of traditional signal acquisition strategy,a set of optimization scheme is put forward,and its reliability is verified.Finally,based on the built diesel engine piston ring dynamic oil film thickness ultrasonic testing platform,the precision analysis of the measurement and acquisition system and diesel engine piston ring dynamic oil film thickness measurement are carried out experimental research.The static calibration experiment of oil film thickness in the range of 1-15 μm was carried out by using the amplitude method of spring model.The relative error between the measurement results and the calibration thickness is small,and the maximum error exists at 13.4 μm,and the difference between the maximum and minimum is 1.85 μm.It is proved that the spring model amplitude method is feasible and accurate in the dynamic measurement of piston ring oil film thickness.Then,with the reflection signal of cylinder wall-air interface as the reference signal,the dynamic oil film thickness measurement experiment of diesel engine piston ring in the range of 10-100r/min speed change was carried out.The results preliminically verified the establishment of the simulation test platform for ultrasonic measurement of diesel engine cylinder oil film thickness.The application of ultrasonic oil film thickness detection method and piston ring dynamic oil film thickness detection is feasible,which improves the experimental basis and reference significance for further study of diesel engine piston assembly oil film thickness measurement under combustion conditions.