Patent ID: 8511289

Claim:
An intake manifold comprising: a surge tank chamber; a plurality of branch passages; a gas tank chamber capable of introducing a gas and distributing the gas into the plurality of branch passages, wherein the gas is to be refluxed to an engine; and a first manifold piece, a second manifold piece, and a third manifold piece made of resin and welded together to jointly form a circumferential wall defining therein the surge tank chamber; wherein: the first manifold piece is positioned between the second manifold piece and the third manifold piece; the circumferential wall of the surge tank chamber includes a side wall including a first boundary plane between the first manifold piece and the second manifold piece welded together and a second boundary plane between the first manifold piece and the third manifold piece welded together; and the side wall has a double wall structure including an inner wall and an outer wall defining therebetween a communication passage communicating with the surge tank chamber.