Exhaust manifold for engine

Abstract

An exhaust manifold for an engine includes a manifold body 7 having a plurality of branch pipes and a common collecting chamber integrally connected to the branch pipes and communicating with an exhaust emission control device is divided into an upper half and a lower half at a boundary face extending in a direction of arrangement of the branch pipes. The upper and lower halves are made of steel plates and welded to each other. In the exhaust manifold, a welding mating coupler is formed by outer edges of the upper and lower halves, and a welding stepped superposing coupler is formed by inner edges of the upper and lower halves. Thus, during welding, it is possible to limit the misalignment of the upper and lower halves in a direction along the boundary face and the misalignment of the upper and lower halves in a direction perpendicular to the boundary face by cooperation of the mating coupler and the stepped superposing coupler. In addition, because the stepped superposing coupler is used for coupling of inner edges of the upper and lower halves to each other, it is possible to ensure sufficient clearances between the adjacent branch pipes, and to easily conduct the operation of mounting of the exhaust manifold to the engine by utilizing the clearances.