Patent ID: 7938100

Claim:
A variable valve device arranged to change a displacement of an intake valve in an engine, comprising: a control shaft arranged to change the displacement of the intake valve by operating a mechanism arranged to drive the intake valve; a motor arranged to rotate the control shaft; a motor driver arranged to drive the motor according to a speed of the engine and an opening degree of an accelerator; a control shaft sensor arranged to detect an actual rotation angle of the control shaft; a control shaft rotation angle estimator arranged to calculate a rotation angle of the motor and to calculate an estimated rotation angle of the control shaft based on the calculated rotation angle; a control shaft sensor failure detector arranged to determine whether or not the control shaft sensor is operating normally; and a combustion state adjuster arranged to control at least one of a fuel injection amount, fuel injection timing, and ignition timing of the engine based on the actual rotation angle detected by the control shaft sensor if the control shaft sensor failure detector determines that the control shaft sensor is operating normally and based on the estimated rotation angle calculated by the control shaft rotation angle estimator if the control shaft sensor failure detector determines that the control shaft sensor is not operating normally.