INTAKE MANIFOLD FOR MULTI-CYLINDER INTERNAL COMBUSTION ENGINE

摘要

An intake manifold (M) for a multi-cylinder internal combustion engine has a collection section (10) for forming an intake collection chamber (11) and also has a branch section (20) for forming an intake branch path (22). The collection section (10) is formed by joining first and second spaces (11a, 11b), which form the intake collection chamber (11), to first and second cases (A, B).Corners (31a, 31b) are formed integrally with the first and second cases (A, B). In the second case (B) is placed a flow straightening section (40) extending across the inside of the first and second cases (A, B) and covering the inner surfaces (31a1, 31b1) of the corners (31a, 31b). The flow straightening section (40) has a guidance surface (44) for more smoothly guiding intake air than the inner surfaces (31a1, 31b1). The flow straightening section (40) and the corners (31a, 31b) together form a rear space (47) communicated with the intake collection chamber (11). The construction smoothens the flow of intake air in the intake collection chamber to improve volumetric efficiency irrespective of the shape of the corners of the intake manifold having a split structure, and in addition, the construction suppresses a pressure variation in the intake collection chamber by utilizing the rear space formed by the flow straightening section.