Intake system with double intake ports for internal combustion engine

Abstract

The present invention relates to an intake system with double intake ports for internal combustion engine, involving two intake ports for each cylinder chamber of the engine, one of the two intake ports being a pure helical port which introduces suction air with helical flow, but without straightway flow, into the cylinder chamber, and another intake port being partially helical port which introduces suction air with helical flow and straightway flow into the cylinder chamber, the outlets of the two intake ports being preferably located in nearer side of the center of the cylinder chamber, and side by side in a parallel direction with the axis of cam shaft; and preferably the pure helical intake port being suspended in lower speed range by pausing device having pause valve which is preferably consisted of suction valve; and the length of suction passage being preferably varied in accordance with the variation of speed ranges.