Abstract: A control device controls a valve timing changer to retard a phase of an exhaust valve camshaft with respect to a crankshaft such that the time of opening of an intake valve is earlier than the time of closing the exhaust valve after a top dead center, when a determiner determines that an engine is not in a warm-up stage in a low-load operation. The control device controls the valve timing changer to advance the phase of the exhaust valve camshaft with respect to the crankshaft such that the time of closing the exhaust valve is earlier than the time of opening of the intake valve after the top dead center, when the determiner determines that the engine is at the warm-up stage in the low-load operation.

Abstract: A control device controls a valve timing changer to retard a phase of an exhaust valve camshaft with respect to a crankshaft such that the time of opening of an intake valve is earlier than the time of closing the exhaust valve after a top dead center, when a determiner determines that an engine is not in a warm-up stage in a low-load operation. The control device controls the valve timing changer to advance the phase of the exhaust valve camshaft with respect to the crankshaft such that the time of closing the exhaust valve is earlier than the time of opening of the intake valve after the top dead center, when the determiner determines that the engine is at the warm-up stage in the low-load operation.

Abstract: A first gear set includes an input member that serves as a first gear and an inner ring that serves as a second gear. A first end of the inner ring is inclined with respect to the input member and is in mesh with the input member. The input member has a plurality of retention grooves that are formed in an input member body and a plurality of pins that are retained in the respective retention grooves and that respectively constitute teeth of the input member. The first end has a plurality of tooth grooves that are engageable with the pins. A resultant force of forces applied to each pin from the retention groove and the tooth groove urges the pin toward the retention groove.

Abstract: An oscillating gear device includes an axially fixed gear piece rotatable around a first axis and an axially oscillating gear piece that oscillates while being inclined with respect to the first axis. A plurality of pins held by one of the gear pieces engage with a plurality of tooth grooves of the other gear piece in engagement regions at a predetermined length in longitudinal directions of the pins. A formula rC0/rF0=ZC/ZF is satisfied, where rC0 is a distance between an arbitrary point on the central axis of the pin in a corresponding section corresponding to the engagement regions of the pin as viewed in the radial direction of the pin and the first axis, rF0 is a distance between the arbitrary point and the second axis, ZC is the number of pins of the one gear piece, and ZF is the number of tooth grooves of the other gear piece.