Patent ID: 7287373
Filing Date: 2007-10-30
Classification: F01N,F02B,Y02T

Abstract:
1. An exhaust pipe collecting structure for a multi-cylinder engine unit having multiple cylinders, in which exhaust pipes extend from at least four cylinders of the multiple cylinders and are collected into one exhaust passage at a location downstream in a flow of exhaust gases, the structure comprising: an exhaust manifold formed in one unitary, integrally cast piece and having an upstream end portion which is connected to the cylinders and including a plurality of exhaust passages corresponding to exhaust ports of the cylinders, respectively; a connecting tube formed in one unitary, integrally cast piece and connected to a downstream end of the exhaust manifold, the connecting tube including a plurality of connecting exhaust passages communicating with the plurality of exhaust passages of the exhaust manifold and being merged into the one exhaust passage at a location inside the connecting tube, the connecting tube being separably connected to the exhaust manifold by a fastening device; wherein at least a downstream end portion of the exhaust manifold includes the exhaust passages which are arranged in two lines and forms an integral tube; and wherein a casting parting plane in casting of the exhaust manifold is provided between the two lines of the exhaust passages.