Swivel device for vehicle seat

A swivel device for a vehicle seat, the swivel device comprising:

• a rotary part including a ring gear and a first pinion gear connected to a first motor and configured to engage with the ring gear;
• and
• a locking device configured to restrict a rotation of the rotary part when an external force is applied to the rotary part when the rotary part is in a stopped state,
• wherein the rotary part further comprises a first mounting bracket on which the ring gear is mounted,
• wherein the locking device comprises:
• a brake housing disposed on an upper portion of the first mounting bracket;
• a brake drum coupled in the brake housing and having guide grooves into which lock pins are to be inserted, the guide grooves being disposed in at least one of an inner-diameter portion and an outer-diameter portion of the brake drum;
• and
• a pulley having a gear portion defined on an outer-diameter portion thereof, the pulley having protrusions configured to be inserted into the guide grooves and defined on one surface of the pulley directed toward the guide grooves, and
• wherein the lock pins are disposed in the guide grooves, and two of the lock pins are disposed at two opposite sides of a protrusion with the protrusion being interposed there between.