Patent ID: 6920854

Claim:
A variable valve actuation (VVA) apparatus for an internal combustion engine, comprising: an intake camshaft which drives an intake valve; an exhaust camshaft which drives an exhaust valve; an intake-side phase alteration device arranged at one end of the intake camshaft, the intake-side phase alteration device changing a relative rotation phase between a crankshaft and the intake camshaft; an exhaust-side phase alteration device arranged at one end of the exhaust camshaft, the exhaust-side phase alteration device changing a relative rotation phase between the crankshaft and the exhaust camshaft; a drive-input rotator provided to the intake-side phase alteration device, the drive-input rotator receiving a torque of the crankshaft; an intake-side transmission rotator provided to the intake-side phase alteration device, the intake-side transmission rotator being disposed closer to the intake camshaft than the drive-input rotator, the intake-side transmission rotator being smaller in outer diameter than the drive-input rotator, the intake-side transmission rotator rotating together with the drive-input rotator; an exhaust-side transmission rotator which receives a torque of the intake-side transmission rotator, the exhaust-side transmission rotator being the same in outer diameter as the intake-side transmission rotator; a reduced-diameter portion arranged between the exhaust-side phase alteration device and the exhaust-side transmission rotator; and a biasing member which biases the exhaust camshaft to an advance direction with respect to the crankshaft, the biasing member having a reduced diameter when a phase of the exhaust-side phase alteration device is changed from its phase at engine start.