Small-size harmonic reducer for robot

The utility model discloses a small-size harmonic reducer for a robot, which comprises a steel wheel, a flexible wheel sleeved on the steel wheel, a wave generator arranged on the flexible wheel, inner teeth arranged on the inner side of the steel wheel, outer teeth arranged on the outer side of the flexible wheel, the outer teeth and the inner teeth are in one-to-one correspondence, a mounting hole is arranged on the steel wheel, and the wave generator comprises an inner wheel. A through opening is formed in the inner wheel, when the flexible wheel rotates, the left side and the right side extrude inwards, and the upper side and the lower side protrude outwards, so that outer teeth on the flexible wheel make contact with inner teeth of the steel wheel, and rotation of the flexible wheel and the steel wheel can be effectively reduced. The steel ring on the inner wheel has extremely high rigidity, meanwhile, the steel balls can rotate on the inner wall of the steel ring, and stable rotation of the speed reduce