To prevent an unable or insufficient state in the drive control of a gear caused by a loss of backlash caused by the expansion of a gear at a high temperature by transferring the drive of an actuator to a variable valve train without using a deceleration region where the backlash of a reduction gear is narrow at a high temperature.
The variable valve device includes: a variable valve train which can vary a lift amount of an intake valve of an internal combustion engine; an actuator which drives the variable valve train; a reduction gear which decelerates the drive of the actuator and transmits the decelerated drive to the variable valve train; a control device which controls the drive of the actuator; and a temperature estimating means which estimates the temperature of the variable valve train. The backlash of the reduction gear is narrower in a deceleration region where a lift amount is decreased than in a deceleration region where the lift amount is increased. The control device controls the drive of the actuator in such a manner that the reduction gear transmits the drive of the actuator to the variable valve train by using only the deceleration region where the lift amount is increased when the estimated temperature of the variable valve train is equal to or higher than a predetermined temperature.
EMORI MITSURU
IDE HIROHITO
TAKAMIYA HIDEJI
NISHINO MASAYOSHI
