Investigation of Compressor Deposit in Turbocharger for Gasoline Engines (Part 1: Research on Deposit Formation Mechanism) 2023-01-0410

Contribution to carbon neutrality is one of the most important challenges for the automotive industry. As CO₂ emission has been reduced through electrification such as hybrid electric vehicle (HEV) and plug-in hybrid electric vehicle (PHEV), internal combustion engines (ICEs) equipped in those powertrain systems are still necessary for the foreseeable future, and continuous efforts to improve fuel efficiency are demanded.

To improve powertrain thermal efficiency, direct-injection turbocharged gasoline engines have been widely utilized in recent years. Super lean-burn combustion engine has been researched as a next generation of turbocharged gasoline engines. Further utilization of turbochargers is expected. Compared with turbocharged downsized gasoline engines available in the current market, much higher boost pressure must be utilized to realize the super lean-burn engines. As a result, compressor housing temperature will be very high compared with the current market one. Blow-by gas containing engine oil mist is always recirculated into intake air upstream of the turbocharger compressor in the boosting operation. Therefore, the possibility of deposit formation derived from the engine oil mist is increased.

It is very important to inhibit the deposit formation for the realization of more efficient turbocharged gasoline engines and the reduction of vehicle CO₂ emission. In this research, it is expected that solutions to inhibit the deposit formation will be found by clarification of the condition and the mechanism of this deposit formation in the turbocharged gasoline engines.