Patent ID: 8677967

Claim:
An intake manifold having a surge tank connected to an air intake passage for air to be supplied to an internal combustion engine, the intake manifold comprising: a gas introduction section communicated to the air intake passage or the surge tank for introducing gas containing fuel component to the surge tank; and a negative pressure feed passage communicated to a portion of the air intake passage or the surge tank which portion is upstream of the gas introduction section in the movement direction of the air and configured to feed a negative pressure inside the surge tank to an outside; wherein the negative pressure feed passage is connected to the air intake passage or the surge tank via an expansion chamber having a larger cross-sectional area than the cross-sectional area of the negative pressure feed passage; wherein the expansion chamber includes a first opening communicated to the negative pressure feed passage and a second opening communicated to at least one of the air intake passage and the surge tank; and wherein the second opening is provided with an opening area greater than that of the first opening.