Patent ID: 8359846
Filing Date: 2013-01-29
Classification: F01N

Abstract:
1. An exhaust manifold comprising: a double collecting pipe that is formed of an inner pipe, including an upper half and a lower half, and an outer pipe, wherein the upper half and the lower half of the inner pipe form a collecting pipe portion and branch pipe portions that are bifurcated from the collecting pipe portion, the branch pipe portions being spaced apart from each other at an upstream end of the double-collecting pipe via a planar thin-walled portion, and the outer pipe covers an outer peripheral portion of the collecting pipe portion, outer peripheral portions of the branch pipe portions and an outer peripheral portion of the thin-walled portion; and an inner pipe retainer that is formed of a pair of semi-circular portions and a connecting portion, wherein the pair of semi-circular portions are respectively connected to outer peripheral portions of branched portions of the branch pipe portions and an inner peripheral portion of the outer pipe, the connecting portion connects the pair of semi-circular portions and abuts the planar thin-walled portion of the inner pipe at a middle section of the inner pipe retainer, and the inner pipe retainer is interposed between the inner pipe and the outer pipe and is connected to the inner pipe and the outer pipe so as to define a gap between the inner pipe and the outer pipe at a downstream end of the double collecting pipe and between the middle section of the inner pipe retainer and the outer pipe at the upstream end of the double collecting pipe, wherein exhaust gas exhausted from exhaust ports of a set of cylinders among a plurality of cylinders of an engine is introduced into the collecting pipe portion through the branch pipe portions, and the planar thin-walled portion of the upper half of the inner pipe abuts the planar thin-walled portion of the lower half of the inner pipe.