Abstract: An intake manifold includes a manifold case having an intake passage. A valve is arranged in the intake passage. The valve is rotatable about its proximal end so as to partly close the intake passage. When the valve partly closes the intake passage, a clearance is formed between a wall surface defining the intake passage and a distal end of the valve. The clearance connects a section of the intake passage upstream of the valve and a section of the intake passage downstream of the valve to each other. When the valve partly closes the intake passage, each of side edges of the valve comes in surface-to-surface contact with a portion of the intake passage wall surface that faces the side edge of the valve, thereby airtightly sealing the spaces between the side edges of the valve and the wall surface of the intake passage.

Abstract: An intake manifold includes a manifold case having an intake passage. A valve is arranged in the intake passage. The valve is rotatable about its proximal end so as to partly close the intake passage. When the valve partly closes the intake passage, a clearance is formed between a wall surface defining the intake passage and a distal end of the valve. The clearance connects a section of the intake passage upstream of the valve and a section of the intake passage downstream of the valve to each other. When the valve partly closes the intake passage, each of side edges of the valve comes in surface-to-surface contact with a portion of the intake passage wall surface that faces the side edge of the valve, thereby airtightly sealing the spaces between the side edges of the valve and the wall surface of the intake passage.

Abstract: An integrated valve device for an intake manifold includes a casing having intake passages each connected to an intake port of an internal combustion engine and a through hole extending perpendicular to the intake passages. A valve shaft is received in the through hole. The valve shaft includes valve portions. Each valve portion is arranged to correspond to one of the intake passages. The valve portions are switchable between a first position, where each valve portion fully opens the corresponding intake passage, and a second position, where each valve portion partly blocks the corresponding intake passage. A recess may be formed in a wall defining each intake passage. In this case, when in the first position, each valve portion is entirely accommodated in the corresponding recess. When in the second position, each valve portion projects from the corresponding recess.