Research The Influence Of Cylinder-piston Lubrication On IC Engine Vibration

Cylinder-piston system is one of the most important friction pairs in internal combustion(IC) engine. The lubrication of cylinder-piston has a great affect on engine body vibration. In most of the past, due to the limit in theory and computer capacity, the lubrication and vibration have been researched separately. In this dissertation, the mechanism of the body vibration signals is elaborated, and the influence of cylinder-piston lubrication on IC engine body vibration is researched by simulation and experiment.The dynamics behavior of IC engine piston and theory of cylinder-piston lubrication are introduced, the mechanism of body vibration signal forming is elaborated as well. The hydrodynamic lubrication and the asperity contact are lead into multi-body dynamic simulation. By building a virtual prototype of single-cylinder IC engine, and a united simulation focused on cylinder-piston system, crankshaft system and oil lubrication, the data of piston lateral displacement, piston angle around the piston pin, the least oil film thickness ratio and piston force on cylinder are systematically obtained. The results indicate that the lubrication of cylinder-piston has a great effect on the force between piston and cylinder. Under the state of asperity contact, decreasing the roughness of cylinder-piston can improve the lubrication between cylinder and piston, and then the impact force between piston and cylinder reduced significantly.For researching the diesel engine body vibration signals, the data acquisition and analysis for vibration signals should be mentioned inevitability. In this dissertation, using graphical programming software Lab VIEW, a complete system for vibration signal testing and analysis is successfully explored. This system use queued state machine as design pattern, which integrated the advantages of state machine structure, event structure and producer/consumer structure, designed the uniform framework of the system module and the apparatus interface, achieved testing and analysis for non-stationary signal, and proved to be practical and availability by applications.In engineering, the surface with regular concave can improve the lubrication and anti-wear effect effectively. In this study, the typical morphology of surface with regular concave is selected, and then the regular concave is designed and machined. Using time domain, frequency main, time-frequency main, discreet wavelet and wavelet packet analysis signal processing means, the changes of IC engine body vibration signals produced by cylinder-piston lubrication improving are studied. It indicated that the high frequency of engine body vibration signals can be decreased by improving cylinder-piston lubrication. Meanwhile, it also shows that using time-frequency method and wavelet packet energy features vector of non-stationary signal analysis is valid.In a word, a virtual prototype of single-cylinder IC engine with tribological behavior is built, and an IC engine vibration signal testing and analysis system is explored, this plants a good base for developing and improving the study on the effect between Cylinder-Piston lubrication and IC engine body vibration.