Method for operating an internal combustion engine

Abstract

The invention relates to a method () for operating an internal combustion engine (), such as an internal combustion engine of a vehicle (), the engine () comprising an engine cylinder () at least partly defining a combustion chamber () and a reciprocating piston (), a number of inlet valves () in fluid communication with the combustion chamber and a number of exhaust valves () in fluid communication with the combustion chamber, wherein any one of the inlet valves and the outlet valves comprises at least one flow control valve. The method comprises the following steps: opening () at least one of the inlet valves and introducing the incoming fluid medium into the cylinder () of the engine by performing an intake stroke (S); compressing () the trapped incoming fluid medium in a first compression stroke (CS) of the cylinder (), while having the number of the inlet valves and the number of the exhaust valves in a closed state; injecting () a quantity of fuel into the cylinder () and combusting said injected fuel; performing () a first work stroke (WS) to produce power to a crank shaft of the engine, while controlling said flow control valve to partly exhaust burnt gases at the end of the work stroke; additionally compressing () remaining fluid medium in an additional compression stroke (CS) of the cylinder (), while having the number of the inlet valves and the number of the exhaust valves in a closed state; additionally injecting () an additional quantity of fuel into the cylinder (); additionally performing () an additional work stroke (WS) to produce power to the crank shaft of the engine, while controlling said flow control valve to partly exhaust burnt gases at the end of the additional work stroke; and opening () at least one of the exhaust valves and permitting partly burnt gases to expel from the cylinder via said at least one exhaust valve by performing an exhaust stroke (ES).