Patent ID: 8201540

Claim:
An internal combustion engine comprising a piston reciprocating in a cylinder; air inlet means communicating with the cylinder; exhaust means communicating with the cylinder; an indirect combustion chamber communicating with the cylinder comprising a near end and a far end in relation to the piston; a transfer orifice communicating with the cylinder and the combustion chamber at its near end; means to promote air movement within the combustion chamber in helical swirl motion having tangential velocity component around the combustion chamber and an axial velocity component along the combustion chamber, the axial velocity component being directed away from the near end and towards the far end; at least one fuel injector communicating with the combustion chamber; a controller to control the fuel injection process and spark ignition event; spark ignition means communicating with the combustion chamber at its far end; characterised in that the far end of the combustion chamber has a substantially concentric protrusion into the chamber facing the near end which forms an annular groove with the periphery of the combustion chamber the protrusion contains a hole for a spark plug which communicates with the said groove through an aperture allowing the spark to be exposed to the air fuel mixture rotating in the said groove to enable direct spark ignition of the mixture.