Internal combustion engine with a subsidiary combustion chamber

An internal combustion engine comprising:

• a cylinder block;
• a piston reciprocably movable in the cylinder block;
• a cylinder head fixed onto the cylinder block and having an intake valve;
• a main combustion chamber formed between the inner surface of the cylinder head and the top surface of the piston;
• a subsidiary combustion chamber disposed in the cylinder head and comprising restricted opening means, a first chamber located in the vicinity of the main combustion chamber and a second chamber located remote from the main combustion chamber, said first and second chambers being interconnected via said restricted opening means, and an ignition plug having an ignition gap located in the first chamber, said first chamber having at least two connecting passages communicating the first chamber and the main combustion chamber, one of said connecting passages being directed to an intake valve so that a part of an air-fuel mixture fed into the main combustion chamber through the intake valve is introduced into the first chamber when the engine is operating under a heavy load, said second chamber on one hand storing a residual gas introduced thereinto from the first chamber through said restricted opening means at the time of the compression stroke when the engine is operating under a light load, and on the other hand, receiving a combustible gas thereinto from the first chamber through said restricted opening means at the time of the compression stroke so that the combustible gas is ignited by the combustion gas in the first chamber when the engine is operating under a heavy load, said restricted opening means delaying a start of the combustion in the second chamber compared with the combustion in the first chamber when the engine is operating under a heavy load.