Patent ID: 8516924

Claim:
A harmonic drive, having at least one air flow opening, the harmonic drive comprising: a circular rigid internal gear; a circular flexible external gear, disposed in the circular rigid internal gear, wherein the circular flexible external gear is a cup-shaped body, and the circular flexible external gear has a cup bottom end; a wave generator, having at least one through hole, and disposed in the circular flexible external gear; a cover, disposed in the circular flexible external gear, and disposed between the cup bottom end and the wave generator, wherein the cover and the wave generator form an air chamber together, and the through hole and the air flow opening are respectively in communication with the air chamber; and a fan blade, wherein the fan blade and the cover are respectively disposed at two opposite sides of the wave generator; wherein, when an external force drives the wave generator and the fan blade to operate, the wave generator forces the circular flexible external gear to perform elastic deformation to be partially engaged with the circular rigid internal gear, such that a part of the circular rigid internal gear engaged with the circular flexible external gear moves along an annular path, the through hole, the air chamber, and the air flow opening form an air flow channel, the fan blade rotates to generate an air flow, and the air flow flows through the air flow channel.