Tribological investigation of the new combustion chamber with wall-guided fuel injection in a diesel engine

Reducing pollutants and increasing thermal efficiency in internal combustion engines is possible by creating better air-fuel mixtures and optimizing the combustion process. In this context, a new combustion chamber providing directed fuel injection was used in a single cylinder diesel engine with a standard combustion chamber. Thus, it was aimed to investigate the tribological behavior of engines with different combustion chambers on long-term engine operation. In engine experiments using two different combustion chambers, the engine was operated at 100 h and partial load. The results of the study showed that changes in combustion chamber structure closely modify engine tribology under the same engine and operating conditions (compression ratio, spray angle and amount, speed, etc.). Looking at the cylinder surfaces examined under an optical microscope, the new combustion chamber showed abrasive wear lines with lower intensity than the standard combustion chamber, while SEM/EDX analysis of the piston ring surfaces showed a similar result. Especially when the analysis of the second ring used in the standard combustion chamber is examined, abrasion occurred in a wider area. Abrasive wear lines were found to be longer, especially in the first ring of the new combustion chamber. It is considered that combustion parameters and exhaust formation processes bring about load/temperature variations of engine lubricating oil and engine components in a chain reaction. This has been found to change the wear levels in engine components and could directly contribute to engine life.