Diagnostics of fuel equipment, gas-distribution valves train mechanism and cylinder lubrication nozzles of modern two-stroke engines

Abstract

The application of a vibration sensor with an in-cylinder pressure sensor extends the capabilities of internal combustion engines and compressor diagnostics for various types of plants and installations, such as marine diesel engines, refrigeration piston compressors, aircraft engines. The fuel injection equipment malfunctions as valve as valve train system malfunctions could be detected from the experimental indicated diagrams P(V), P(deg) of the engine cylinder operating process as it is known. The main indicators are the following: the shape of the diagram and the parameters of working cycle – the maximum combustion pressure Pmax, the compression pressure Pcomp, mean indicated pressure IMEP, etc. However, it should be considered that different types of malfunctions could have the same reflection on the indicated diagram. For instance, the late fuel injection and the fuel-injection equipment wear could have almost similar effects on the indicated diagram and main diagnostic parameters. Another example is the low compression pressure Pcomp, which could be caused by the cylinder or compression rings wear and by the exhaust valves wrong timing or valve leakage.  It should also be mentioned that many types of malfunctions at their early stages are very difficult to detect and clarify based solely on the indicated diagrams analysis. The detection of such malfunctions usually requires the direct measurements of the fuel injection pressure and injector’s needle lift diagrams with accurate valve timing measurements. However, mentioned measurements could be performed under laboratory conditions and are difficult to apply under engine operating conditions. The vibration sensor application could be a reasonable alternative to the direct measurements, as it allows the determination of the injector’s needle lift-off and landing timing, high-pressure fuel pump cut-off and discharge timing, the preheated heavy fuel circulation start/stop timing as well as gas-distribution valves opening and closing timing, the oscillation frequency, and amplitude from the refrigeration system piston compressor valve operation and the cylinder oil injector timing. The vibration sensor has a magnetic basement that allows its easy mounting on the engine parts. All this information could be directly measured during engines and compressor trials by the vibration sensor applied in the advanced diagnostic systems.