Fuel injection system for a lean burn engine

摘要

According to the present invention, each of the cylinders of an engine is provided with a swirl port, which generates a swirl in the cylinder, and a conventional straight port. A swirl control valve is disposed in an inlet air passage connected to the straight port for blocking the flow of inlet air through the straight port. A fuel injection port is disposed in each of the swirl port and the straight port. The fuel injection port in the straight port is disposed at the position adjacent to the upper edge of the valve seat of the straight port inlet valve. When the swirl control valve blocks the inlet air passage leading to the straight port, fuel is injected from the fuel injection port of the straight port in the latter half of the intake stroke of the piston. The direction of fuel injection from the fuel injection port in the straight port is determined in such a manner that fuel is injected in the direction between the center axis of the cylinder and the center axis of the stem of the valve element of the inlet valve toward the opposite wall of the cylinder head or the upper part of the opposite wall of the cylinder.