A HELICALLY-SHAPED INTAKE PORT OF AN INTERNAL-COMBUSTION ENGINE

摘要

An engine comprising an intake port which has a separating wall projecting downwardly from the upper wall of the intake port. The separating wall defines a helical portion, an inlet passage portion tangentially connected to the helical portion, and a bypass passage interconnecting the inlet passage portion and the helical portion. The intake port has a bottom wall having a transverse width which is approximately equal to the diameter of the valve head of the intake valve. The opposed peripheral edges of the bottom wall are located on the extensions of the tanget lines of the outer periphery of the valve head of the intake valve. A rotary valve is arranged in the bypass passage and is actuated by a vacuum-operated diaphragm apparatus. The rotary valve is opened when the amount of air fed into the cylinder of the engine is increased beyond a predetermined value.