The invention discloses a motor
assembly for lifting a seat. The motor
assembly comprises a motor, a reduction box body, a worm, a mounting bracket, a duplicate gear, a movable bracket, a mobile gear, an output gear
assembly and a reduction box cover, wherein the reduction box cover is fixedly connected with the mounting bracket and the reduction box body, so as to enable the duplicate gear, the mobile gear, the movable bracket and a part, except for an output gear, of the output gear assembly to be sealed in an assembly chamber which is formed by the internal surface of the reduction box cover and the internal surfaces of the reduction box body; the motor drives a wormgear in the duplicate gear to rotate through the worm, the wormgear drives a movable bracket
drive shaft, which is integrated with the wormgear, to eccentrically rotate, the movable bracket is driven to do up-and-down movement in a
radial plane and drives the mobile gear to do elliptical-trajectory motion during up-and-down movement, the output gear assembly is driven to rotate through enabling the mobile gear to be engaged with an inner gear ring in the output gear assembly, the output gear engaged with a fan-shaped gear plate, and the fan-shaped gear plate is driven to rotate through engaged transmission so as to adjust the height of the seat.