Combustion space of a piston driven internal combustion engine

Claim 1

A combustion space of a reciprocating piston internal combustion engine having piston means and cylinder head means for delimiting a combustion space, said combustion space being located in part within the piston means and in part within the cylinder head means, recess means centrally disposed in an end surface of said piston means and an upwardly arched wall in said cylinder head means together forming a substantially axially symmetrical combustion space, said upwardly arched wall including an inlet valve and an exhaust valve and means for causing ignition, said piston means with said recess means and said cylinder head means cooperating to form an endless vortex flow from an outer potential flow and an inner concentric rotary flow in the combustion space by dimensioning and coordination to the inlet valve and exhaust valve, the axes of the inlet valve and the exhaust valve each being disposed at an acute angle to the piston axis, the means for ignition including at least two spark plugs with ignition electrodes protruding into the combustion space, one of said at least two spark plugs being disposed on an opposite side of a plane passing through the axes of the intake and exhaust valves from another of said at least two spark plugs, and ignition electrodes of said opposed spark plugs being disposed at different distances from the piston axis such that when the middle diameter of a mixing zone of high fuel concentration formed between the rotary flow and the potential flow increases with decreasing engine rotational speed the mixing zone moves such that one of the opposed ignition electrodes is in the mixing zone and when the middle diameter of the mixing zone decreases, another of the opposed ignition electrodes is in the mixing zone.