Intake system for direct fuel injection diesel engine

Abstract

An intake system for a direct fuel injection diesel engine is disclosed which has a cylinder block with a cylinder slidingly receiving a piston. A cylinder head is mounted on the cylinder block, and a fuel injector is adapted to directly inject fuel into a combustion chamber formed between the lower side of the cylinder head and the upper side of the piston, wherein the cylinder head has first and second intake passages which are independent of each other and which are adapted to introduce air into the combustion chamber. The first intake passage is oriented substantially tangentially to the combustion chamber and substantially orthogonally to the axis of the cylinder, and has a helical end portion opening into the combustion chamber to form a swirl of air flowing therethrough. The second intake passage is oriented such that the end portion thereof, adjacent the combustion chamber, is closer to the central axis of the cylinder than the end portion of the first intake passage adjacent the combustion chamber. The second intake passage is provided with an intake controller which prevents air from flowing in the second intake passage at low engine speeds but allows air to flow in the second intake passage at high engine speeds.