Optimization of Negative Crankcase Pressure Mechanism to Minimize Oil Pumping into Combustion chamber and Ensure Particulate Number Compliance in Euro VI Emission for Naturally Aspirated Gas Engine.

Emissions regulations, such as Euro VI, drives the Automotive industry to innovate continuously in Engine development. One significant challenge is the engine oil pumping from the crankcase into the combustion chamber, where it participates in combustion, which contributes to increased Particulate Numbers and fails to meet Euro VI emission compliance. This issue is most noticeable during engine idling and motoring conditions. During this time, a higher negative pressure difference develops between the intake manifold, which is acting above the combustion chamber and the engine crankcase. Within the crankcase, engine oil is present along with aerosols carried in the blow-by gas. This pressure difference causes oil passes through piston rings during suction stroke and valve stem seals in Naturally Aspirated Gas engines. The impact of the pressure difference between the intake manifold and crankcase was studied by varying the crankcase pressure through crankcase ventilation system. The results confirm that oil entry into the combustion chamber, contributing to combustion, occurs primarily through the piston rings, contributing to increase in Particulate Number. To address this issue, it becomes necessary to introduce a mechanism that optimizes negative crankcase pressure across varying engine operating conditions. By reducing the pressure difference between the intake manifold and crankcase, this mechanism prevents oil entering the combustion chamber, thereby minimizing Particulate Number emissions and ensuring Euro VI compliance. This study focuses on the development and implementation of a negative crankcase pressure control system via the crankcase ventilation system. Through targeted optimization, it provides an effective way to control oil pumping into the combustion chamber, thereby enhancing emission control and advancing the development of cleaner Naturally Aspirated Gas engines.