Direct-injection diesel engine

Claim 1

A direct-injection diesel engine comprising a cylinder block having a plurality of cylinders in which a piston is slidably received in each cylinder, a cylinder head connected to an upper surface of the cylinder block, a plurality of fuel injector nozzles mounted in the cylinder head with at least one said nozzle to directly inject a fuel into a combustion chamber defined between each said piston and the cylinder head,, first and second independent intake ports provided in the cylinder head for introducing an intake gas into each said combustion chamber, a single exhaust port provided in the cylinder head for each combustion chamber, an intake controller mounted in each second intake port for bringing the second intake port into a controlled state in a region of low speed operation of the engine and into a normal state in a region of high speed operation of the engine, wherein each of said first and second intake ports are formed helically in the same direction to produce swirls in the same direction in intake gases introduced respectively through the intake ports into each combustion chamber and wherein downstream openings of the first and second intake ports are disposed in locations of substantially point symmetry with respect to the fuel injector nozzle position in each combustion chamber whereby a swirl in the intake gases is produced in both low and high speed operation of the engine, and a downstream opening of the exhaust port disposed adjacent one of the first and second intake ports in each combustion chamber in a direction of arrangement of the plurality of cylinders.