Internal combustion engine

Claim 1

An internal combustion engine comprising: a cylinder block having a cylinder bore therein; a cylinder head secured to the cylinder block; a piston reciprocably disposed in the cylinder bore, said piston having a head with a flat upper surface; a main combustion chamber, to which only air is directly supplied, defined by the cylinder bore, said piston, and said cylinder head; an auxiliary combustion chamber, circular in cross-section, defined in the cylinder head above the main combustion chamber; an ignition plug having an electrode in said auxiliary combustion chamber; a fuel injection nozzle in said auxiliary combustion chamber; means defining a passage in the cylinder head for fluidly communicating the main combustion chamber and the auxiliary combustion chamber, said passage being disposed tangentially to the periphery of the auxiliary combustion chamber, extending at an angle of no more than 45° to the upper surface of the piston head, and having a cross-sectional area of 1 to 10% of the transverse cross-sectional area of the piston head, one end of said passage opening into said main combustion chamber and the other end thereof opening directly into one end of said auxiliary combustion chamber in a direction directly toward said ignition plug, said passage being in the form of a flat envelope in cross-section with flat sides and substantially semi-circular ends and having a major axis, parallel to the upper surface of the piston head, and a minor axis within the ratio of 1.5 to 3 in length; said fuel injection nozzle is positioned adjacent a portion of the auxiliary combustion chamber diametrically opposite said one end thereof; and said electrode is positioned between said passage and said fuel injection nozzle.