Patent ID: 7261085

Claim:
An arrangement for controlling combustion in a combustion engine, the combustion engine comprising: a combustion chamber; a movable piston in the combustion chamber and movable in the chamber for compressing a fuel mixture in the combustion chamber so that self-ignition of the fuel mixture takes place; a crankshaft driven to rotate by movements of the piston; an inlet valve to the combustion chamber and an exhaust valve from the combustion chamber; a control unit operable for controlling the self-ignition of the fuel mixture to an optimum crankshaft angle (cad iopt ) of the crankshaft within a load range (L tot ) of the engine, wherein the load range (L tot ) can be divided into at least two subranges (L I , L II ); the control unit being operable for controlling the self-ignition of the fuel mixture towards an optimum crankshaft angle (cad iopt ) within a first subrange (L I ), the control unit being operable to perform by a strategy (I) which supplies a variable amount of hot exhaust gases to or to be retained in the combustion chamber, and within a second subrange (L II ), and the control unit being operable to perform by another strategy (II) which varies the effective compression ratio (c) in the cylinder.