Patent ID: 7191054

Claim:
A fail-safe control apparatus for an internal combustion engine, comprising: a plurality of variable valve characteristic mechanisms which vary different operating characteristics of an intake valve; and a control unit that controls said plurality of variable valve characteristic mechanisms, wherein said control unit: detects whether or not there is a failure with respect to said plurality of variable valve characteristic mechanisms; when it is detected that any of the variable valve characteristic mechanisms fails in varying an operating characteristic of the intake valve, sets a limit for advancing the opening timing of the intake that (a) is on the retarded side of an advance limit of a range in which the intake valve does not interfere with its associated piston, and (b) maintains a remaining burned gas amount, which exists at the time when another valve operating characteristic is varied by a normally operable one of the plurality of variable valve characteristic mechanisms, at a reference value or less that substantially prevents deterioration of combustion stability; and controls the operating characteristics of the intake valve, while limiting the opening timing of the intake valve by said set limit for advancing the opening timing of the intake valve, by way of the normally operating variable valve characteristic mechanism.