Development Of The Internal Combustion Engine Vibration Test System And The Experimental Study On Vibration Characteristics Of RCCI

When the engine is working, there always be a severe vibration with it. Noise and vibration reduction has attracted more and more attention in the internal combustion engine research in recent years. Internal combustion engine vibration is closely related to its cylinder combustion, it directly reflects the working condition of the internal combustion engine. Vibration testing is more economical compared with in-cylinder pressure testing, and the layout and installation of the vibration testing system is more convenient, so it has an important significance and practical value to research engine combustion with vibration measurement and analysis.This paper introduced a self-developed vibration measurement and analysis system based on LabVIEW. This system is used to study the combustion process by vibration of the engine. The system can achieve online vibration data acquisition, real-time curve display and data storage. So it can not only be used to study the engine vibration but also do engine monitoring. In addition, with the help of off-line analysis function, we can do time domain analysis, frequency domain analysis and time-frequency analysis for the engine vibration to study the combustion process. Meanwhile, fault diagnosis can be achieved by vibration signal analysis.RCCI is a new type of combustion, compared with conventional combustion, it has a distinct advantage in heat rate improvement, NOX and soot emissions reduction. In this paper, we innovatively use the self-developed test system to study the vibration of the RCCI engine compared with its in-cylinder pressure. In the RCCI mode, the amplitude of the vibration signal in low and medium frequency increased with the increasing of the PFI duration at high load, while at low load, it reduced when the PFI duration increased. At the same time, with the amount of injected gasoline increasing, there is a trend to have combustion knocking. Finally, the system was used to do fault diagnosis for the diesel engine valve clearance. It shows that when the valve clearance increases, only the amplitude of high frequency signal has significantly increased, there is little change in low and medium frequency signal.