Patent ID: 8407940

Claim:
A vehicle door driving apparatus, comprising: a drive mechanism secured inside a vehicle door, wherein the drive mechanism opens and closes a door opening formed in a vehicle body, the drive mechanism including a motor and a drum, wherein the drum is rotated by the motor; and a rope member wound about the drum and coupled to the vehicle body, wherein the vehicle door is opened and closed as rotation of the drum is converted to force applied to the vehicle body via the rope member, wherein the drum is arranged inside the vehicle door such that the drum at least partially overlaps with a space having a dimension in the lateral direction of the vehicle defined by an outer shape of the motor, the drive mechanism including: a first small-diameter gear portion coupled to a rotary shaft of the motor to rotate integrally with the rotary shaft; a transmission gear, which is freely rotational about an axis extending in the lateral direction of the vehicle, the transmission gear including a first large-diameter gear portion, which is meshed with the first small-diameter gear portion and forms a gear pair with intersecting axes or a hypoid gear together with the first small-diameter gear portion, and a second small-diameter gear portion, which is arranged on an opposite side of the first large-diameter gear portion in the axial direction of the transmission gear; a sun gear, which is freely rotational about an axis extending in the lateral direction of the vehicle, the sun gear including a second large-diameter gear portion, which is meshed with the second small-diameter gear portion, and a sun gear portion, which is arranged on the same side of the second large-diameter gear portion as the rotary shaft; a ring gear arranged coaxially with the sun gear and radially outward of the sun gear portion, the ring gear serving as a fixed shaft; and a carrier including a planet gear meshed with the sun gear portion and the ring gear, and the carrier being coupled to the drum to rotate integrally with the drum.