Variable swirl intake apparatus for engine

Claim 1

In a variable swirl intake apparatus for an engine, comprising: an intake port formed in a cylinder head of the engine and including an entrance portion extending from a side surface of said cylinder head, and a swirl chamber which communicates with said entrance portion and is formed to provide a swirl to an air flow introduced from said entrance portion, said swirl chamber having an opening opened to a lower surface of said cylinder head and communicating with a cylinder chamber; a valve seat formed in the lower surface of said cylinder head along the peripheral edge of the opening of the swirl chamber; and an intake valve for opening and closing said opening of the swirl chamber in association with said valve seat; said opening of the swirl chamber having a center thereof located eccentrically with respect to the center of the cylinder chamber, and first and second regions which are defined by a line extending through the center of the opening and the center of the cylinder chamber, said intake port being arranged so that, of the air flowing into said cylinder chamber from said swirl chamber through a gap formed between said valve seat and said intake valve, the part flowing from the first region of said opening generates, within said cylinder chamber, a forward swirl of air circulating in one direction around the axis of said cylinder chamber and the part flowing from the second region of said opening generates, within said cylinder chamber, a reverse swirl of air circulating in the opposite direction around the axis of said cylinder chamber, the improvement which comprises: a swirl control path formed in the cylinder head, for introducing air into said cylinder chamber, said swirl control path having a first end located near said valve seat and being open to said second region of said opening, and a second end located above said entrance portion and being open to the side surface of said cylinder head, and that portion of said swirl control path, which extends from the second end to the approximate middle part of the path, being located above said intake port, and that portion of said swirl control path, which extends from the middle part to the first end, extending downward and being slightly inclined to the axis of said cylinder chamber so that the air flowing from the first end of said swirl control path into said cylinder chamber swirls in said opposite direction to thereby control the strength of the forward swirl within said cylinder chamber; and control means provided within said swirl control path, for controlling the amount of the air flowing into said swirl control path.