Abstract: A system for blow-by gas return to the combustion chamber of an engine according to the present invention including an oil separator with an inlet communicating with an outlet through a diffusion chamber and a filter element; said oil separator communicating with the crankcase of the engine through a breather and an inlet pipe, and also communicates with the intake manifold of the engine through an outlet pipe, so as to separate the oil from the blow-by gas almost completely. The oil separator and the inlet and outlet pipes are disposed in a space directly over the cylinder head of the engine and the intake manifold, so as to prevent ice accumulation therein by the radiation and convection of engine heat thereon.

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.

Abstract: An apparatus for the return of crankcase vapors into a combustion chamber of an internal combustion engine, and for separating lubricating oil mist in the crankcase vapors. Some of the lubricating oil mist being removed primarily with a breather device and the residual oil mist being separated secondarily with an oil-bath type air cleaner, by directing the vapors into the air cleaner through a vapor passage.