The invention discloses a
cycloid planetary transmission gear based on line-surface conjugation, and relates to a
cycloid planetary transmission gear which comprises a
cycloid pin wheel planetary transmission meshed pair. A smooth
curve line inverted L (2) is selected on a gear surface of a gear in the meshed pair, the main normal vector direction is consistent with the normal direction of the gear surface, and the
curve line inverted L (2) and the gear surface of another gear in the meshed pair form line-surface conjugation mesh; the gear surface of the gear is a tubular meshed surface which is a sphere family enveloping surface sigma (3) of which the sphere center moves along an
equidistant line inverted L (3); the
equidistant line inverted L (3) is a smooth
curve line which has a distance of r from the main normal vector direction; the spherical
radius of spheres in the sphere family is the distance r between the
equidistant line inverted L (3) and the smooth curve inverted L (2), and the r is less than the minimum curvature
radius of the meshed section of the original gear surface. According to the invention, through changing the cycloid planetary transmission into the line-surface conjugation meshed pair, the meshed process is in the mode of
point contact, the
transmission ratio is great, the rigidity is good, the structure is compact, the transmission accuracy is high, the mesh can be approximately to pure rolling, the sliding ratio can be reduced greatly, thus the efficiency is improved greatly, the service life is improved, the manufacturing is simple, and the accuracy is high.