Engine having a plurality of intake ports for each cylinder

摘要

The engine has first and second intake ports (11, 12) for each cylinder (3) and these intake ports (11, 12) extend generally parallel to each other. The cylinder (3) defines a combustion chamber. The first intake port (11) opens to the combustion chamber (3) at its exit opening (15) and a first swirl (S1) is generated from the first intake port (11). The second intake port (12) opens to the combustion chamber (3) at its exit opening (26) and a second swirl (S2) is generated from the second intake port (12). The first and second swirls (S1, S2) become a collective swirl (S) in the combustion chamber (3). The collective swirl (S) flows or rotates along an inner peripheral wall of the cylinder (3). The first intake port exit opening (15) is downstream of the second intake port exit opening (26) in terms of a rotating direction of the collective swirl (S). The second intake port (12) has a recess (14) near its downstream end to reverse an air flow in the second intake port (12) such that the second swirl (S2) is directed to a tangential direction of the combustion chamber (3). The first intake port (11) has a projection (13a) such that the first swirl (S1) is entirely directed to a tangential direction of the combustion chamber (3) whereby the first and second swirl (S1, S2) do not conflict in the combustion chamber (3). <IMAGE>