Characteristics of Lubricants on Auto-ignition under Controllable Active Thermo-Atmosphere 2016-01-0889

Downsizing gasoline direct injection engine with turbo boost technology is the main trend for gasoline engine. However, with engine downsizing and ever increasing of power output, a new abnormal phenomenon, known as pre-ignition or super knock, occurs in turbocharged engines. Pre-ignition will cause very high in-cylinder pressure and high oscillations. In some circumstances, one cycle of severe pre-ignition may damage the piston or spark plug, which has a severe influence on engine performance and service life. So pre-ignition has raised lots of attention in both industry and academic society. More and more studies reveal that the auto-ignition of lubricants is the potential source for pre-ignition. The auto-ignition characteristics of different lubricants are studied. This paper focuses on the ignition delay of different lubricants in Controllable Active Thermo-Atmosphere (CATA) combustion system. In this study, many tests were conducted in the CATA combustion system .The result of tests shows that with the increase of the temperature, the ignition delay of the oil decrease obviously. And the results of tests show that with the increase of the kinematic viscosity, the ignition delay increase. But with the increase of the calcium content, the ignition delay decrease drastically. And the evaporation loss has almost no influence on the ignition delay of the oil.

Different lubricants have different auto-ignition characteristics, which may influence the pre-ignition frequency in gasoline engine. The Controllable Active Thermo-Atmosphere (CATA) is proved to be an effective facility to study the auto-ignition characteristics of lubricants.