The invention belongs to the technical field of speed reducers, and relates to a planetary
harmonic combined speed
reducer. A gear shaft, a planetary gear, a
planet carrier, a rigid wheel and a pin shaft form a one-stage planetary reduction
gear train, the rigid wheel is fixed, the gear shaft is used for being connected with external input equipment as an input part, and plays a role in a sun wheel at the same time, the planetary gear is meshed with a first inner gear ring of the rigid wheel and a gear part of the gear shaft at the same time so as to rotate around the pin shaft and rotates around the gear shaft at the same time, and the
planet carrier serves as an output part and transmits the output to a wave generator. The wave generator, a flexible wheel, the rigid wheel and a first bearing form a secondary
harmonic reduction
gear train, under the action of the wave generator, the flexible wheel is deformed forcibly, an outer gear ring is in meshed transmission with a second inner gear ring, and the first bearing is connected with external output equipment so as to output power. The first inner gear ring and the second inner gear ring are arranged on the rigid wheel, so that a planetary reduction
train and the
harmonic reduction
train share an inner gear, the number of parts is reduced, and the
reducer has the advantages of being simple and compact in structure, convenient to assemble, high in
speed reduction ratio, small in size, high in transmission precision and the like.