Fuel injection type internal combustion engine

Claim 1

In an internal combustion engine comprising: a cylinder block having a cylinder bore therein; a piston reciprocally movable in said cylinder bore and having a flat top face; a cylinder head having a circular inner wall portion covering the cylinder bore and comprising a flat portion substantially parallel to the top face of the piston and a recessed portion which is arranged adjacent to the periphery of said inner wall and has a circumferential wall and a top wall, said flat portion being arranged at a position close to the flat top face of said piston when the latter is positioned at top dead center for forming a squish area therebetween, said piston and said circular inner wall portion of said cylinder head forming a combustion chamber therebetween; an intake valve arranged on said flat portion and having a valve head which has a front face exposed to said combustion chamber, the front face of said valve head being approximately coplanar with said flat portion; an exhaust valve arranged on the top wall of said recessed portion and having a valve head; a groove formed in said flat portion and extending from the valve head of said intake valve to said recessed portion, said groove having an approximately uniform depth which is slightly larger than the clearance between said flat portion and the flat top face of said piston when the latter is positioned at top dead center; a depression formed in said groove adjacent to and opening into said recessed portion, said depression having a flat inner wall which is inclined downwardly and slightly towards said recessed portion with respect to a plane parallel to the axis of the cylinder bore and passing through the centers of said intake and exhaust valve heads; a spark plug arranged in a bore in said inclined wall of the depression in said groove and having a spark gap located approximately on the axis of the cylinder bore, so that the flame propagation distances to the most remote surfaces of the circumferential walls of the recessed portion are minimized; and an intake passage formed in said cylinder head and connected to said combustion chamber via said intake valve, said cylinder head having a portion which is located between said recessed portion and said intake passage, and which portion has a wall portion defining part of said intake passage; the improvement wherein a fuel injector is arranged in said intake passage and has a nozzle which is directed to said wall portion.