Patent ID: 8176904

Claim:
An intake system for an internal combustion engine, comprising a first intake passage having an upstream end communicating with an intake duct and a downstream end communicating with an intake port of an engine cylinder, a first intake control valve provided in the first intake passage, a second intake passage having an upstream end communicating with the intake duct and a downstream end communicating with the intake port of the engine cylinder, a second intake control valve provided in the second intake passage and a control unit for controlling opening angles of the first and second intake control valves, wherein: the control unit is configured to start opening the second intake control valve when the first intake control valve has opened to an effective opening angle which depends on a rotational speed of the engine and is defined in a region where a change in the intake air flow rate of the first intake passage for a given change in the opening angle of the first intake control valve falls below a prescribed level.