In order to understand the major mechanisms that drive oil transport which may lead to oil consumption, a special experimental setup is developed by the Sloan Automotive Lab for visualizing the oil transport in the piston ring pack.
The research engine is modified from an inline-4 PSA production engine, with 3 cylinders deactivated and one fitted with an optical engine liner. The engine liner is modified such that an optical window can be press-fitted onto it. During engine operation, a laser beam is shot through the window into the piston ring pack, which excites the fluorescent dye mixed into the engine oil. The oil movement can thus be captured by a high-speed camera system for visualization purposes.
The engine control system is based on a field-programmable gate array (FPGA) system that includes National Instrument hardware and software. The FPGA system controls fuel injection and ignition, and data is collected by a Windows computer and cDAQ system. The FPGA triggers the high-speed camera, which allows the critical operation times to be synchronized.
The custom-made optical liner consists of a transparent sapphire window of 12mm width and 98.5mm length along the piston moving direction on the thrust side. The camera has two defined views: full view with 128×1024 resolution recording the whole optical window; magnified view with 1024×1024 resolution focusing on a 12mm×12mm area at a set position. Furthermore, both high-speed camera control and slow-speed camera control were applied to serve different purposes. High-speed mode can record as fast as 12500fps with a 1/16000s shutter speed, around 1 frame per crank angle at 2000rpm. Slow speed camera can capture one frame per cycle at a set crank angle (CA) position to capture the oil accumulation evolution over longer time scales.