Internal combustion engine with an auxiliary combustion chamber

Claim 1

An internal combustion engine comprising: a cylinder having a cylinder block and a cylinder head fixed onto said cylinder block; a piston reciprocally movable in said cylinder block; a main combustion chamber formed between a top surface of said piston and an inner surface of said cylinder head; an intake valve movably mounted on the cylinder head for leading a combustible mixture into the main combustion chamber; an exhaust valve movably mounted on the cylinder head for discharging an exhaust gas into the atmosphere; means to supply fuel directly only to said main combustion chamber, said cylinder head having therein an auxiliary combustion chamber extending symmetrically about an axis, said auxiliary combustion chamber having a circumferential inner wall including a raised annular portion defining a restricted opening interconnecting and of smaller diameter than a substantially spherically shaped first portion of said auxiliary combustion chamber located near the main combustion chamber and a second portion of said auxiliary combustion chamber located further from the main combustion chamber than the first portion, wherein said restricted opening is the only opening in said second portion of said auxiliary combustion chamber, the volume of said first portion of said auxiliary chamber is smaller than the volume of said second portion of said auxiliary chamber, the ratio of the diameter of said annular portion to the diameter of said second portion of said auxiliary chamber is less than 0.8, and the diameter of the second portion of the auxiliary chamber is greater than the axial length of said second portion, a single passage means connecting the main combustion chamber and the auxiliary combustion chamber through the circumferential wall of said first portion of said auxiliary chamber, the inner end of said passage means being substantially tangentially disposed relative to the circumferential wall of said first portion of said auxiliary chamber and extending to the main combustion chamber so as to create a swirling motion of a combustible mixture in the first and second portions of said auxiliary combustion chamber, and a spark plug having a spark gap located in the vicinity of said symmetrical axis and the second portion of said auxiliary combustion chamber, said restricted opening allowing the flow of a combustion gas from said second portion to said first portion, both of which portions are of greater diameter than the restricted opening, said combustion gas being collected in the vicinity of said symmetrical axis after said combustible mixture is ignited, while said restricted opening prevents outflow of unburned mixture from said second portion to said first portion, said unburned mixture being collected on the peripheral region in said second portion removed from said symmetrical axis due to the centrifugal force caused by said swirling motion of said combustible mixture, and wherein said single passage means has an opening which is directed in a circumferential direction with respect to the inner wall of said main combustion chamber.