Method for operating an internal combustion engine

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 operable between a bottom dead center and a top dead center, a number of inlet valves in fluid communication with the combustion chamber and configured to regulate the supply of an incoming fluid medium to the combustion chamber and a number of exhaust valves in fluid communication with the combustion chamber and configured to regulate the evacuation of exhaust gases from the combustion chamber, wherein any one of the inlet valves and the outlet valves comprises at least one flow control valve adapted to regulate the flow of a fluid medium passing through the flow control valve, characterized by the method comprising 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;
• compressing the trapped incoming fluid medium in a first compression stroke 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, resulting in burnt gases and remaining fuel medium;
• performing a first work stroke to produce power to a crank shaft of the engine, while controlling said flow control valve to partially exhaust the burnt gases at the end of the work stroke, thereby reducing the pressure in the cylinder, resulting in an exhausted first portion of the burnt gases and a remaining second portion of the burnt gases;
• compressing the remaining fluid medium in an additional compression stroke of the cylinder, while having the number of the inlet valves and the number of the exhaust valves in a closed state;
• injecting an additional quantity of fuel into the cylinder, resulting in a mixture of the additional quantity of fuel, the remaining fluid medium, and the remaining second portion of the burnt gases;
• combusting the mixture of the additional quantity of fuel, the remaining fluid medium, and the remaining second portion of the burnt gases;
• performing an additional work stroke to produce power to the crank shaft of the engine, while controlling said flow control valve to partially exhaust burnt gases due to combustion of the mixture at the end of the additional work stroke, thereby reducing the pressure in the cylinder;
• repeating the steps of additionally compressing remaining fluid medium in an additional compression stroke 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, and additionally performing an additional work stroke to produce power to the crank shaft of the engine, while controlling the flow control valve to partly exhaust burnt gases at the end of the additional work stroke, thereby reducing the pressure in the cylinder, until the quantity of the remaining fluid medium in the cylinder is below a threshold value;
• 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.