Patent ID: 8118007

Claim:
An air intake device for an engine comprising: (a) a housing, in which an air-intake passage connected to an intake port of the engine is formed; (b) a shaft rotatably supported by the housing; and (c) a U-shaped rotary valve having connecting portions connected to the shaft and reciprocating in a rotational direction for changing an opening area of the air-intake passage, wherein the housing has an air duct, which surrounds an outer periphery of the air-intake passage and extends from an upstream side to a downstream side of intake air flow so that the air duct passes through an inside space defined by the U-shaped rotary valve, wherein the rotary valve has a pair of side plates extending outwardly from the connecting portions in a radial direction of the shaft, so that the side plates are separated from each other at an axial distance in parallel to the shaft and opposed to each other in an axial direction of the shaft, wherein the rotary valve further has a valve plate connected to each free end of the side plates, which is on an opposite side to the connecting portion, wherein the valve plate faces to a downstream end of the air duct via a gap between the valve plate and the air duct, when the rotary valve is moved to its valve closed position, and wherein the side plates cover opened areas of the gap in a lateral direction in parallel to the axial direction of the shaft, when the rotary valve is in its valve closed position.