Method for Externally Controlled Availability of Lubricating Oil in Internal Combustion Engines

Reduced raw emissions from internal combustion engines (ICE) are a key requirement to reach future green-house-gas and pollutive emissions regulations. In parallel, to satisfy the need for increased engine efficiencies, the friction losses of ICEs gains attention. Measures to reduce parasitic drag inside the piston assembly such as reduced piston-ring pretension or thinner grade engine oils may increase oil ingress into the combustion chamber. The oil ingress is known to imply increased particle emissions directly counteracting the raw emission reduction target of engine development. To resolve this target conflict, the transport mechanisms of oil into the combustion chamber are the topic of current research. Specially developed research engines featuring a vertical optical window come with big potential to visualize the phenomena of the oil behavior inside the piston assembly group. Such ‘glass-liner’ engines play a pivotal role in identification and quantification of local and global phenomena and their correlating operating parameters. The objective of this study is to develop and investigate a novel approach facilitating active control over the amount of oil available in the piston group assembly under varying operating parameters. The mechanical incorporation into the engine relies on ports embedded into the cylinder wall. These ports facilitate accessing the ring-land areas to realize fluid flow out of the piston group assembly using either vacuum or compressed air. The system is investigated in both a ‘glass-liner’ as well as a thermodynamic engine. Optically, the amount of oil present at the piston surface as well as residual oil on the cylinder wall is evaluated. A reduction of up to 40 percent of the indicated LIF-intensity from the residual oil on the cylinder surface can be shown. Similar results from tailpipe measurements are also demonstrated.