| 摘要 |
PCT No. PCT/JP91/00024 Sec. 371 Date Sep. 1, 1992 Sec. 102(e) Date Sep. 1, 1992 PCT Filed Jan. 14, 1991 PCT Pub. No. WO92/12360 PCT Pub. Date Jul. 23, 1992.A planetary speed-up and -down gearing comprising an external gear having outer teeth (7A) defined by a trochoidal curve and an internal gear having outer pins (9) internally meshed with the outer teeth (7A) of the external gear and being eccentric with respect to the external gear, the external gear and the internal gear being meshed and rotated eccentrically and swingingly relative to each other, so that phases of the external gear and the internal gear are shifted by a difference in the number of teeth between both said gears for each of the eccentric and swinging rotations, to thereby take out, as an output, rotation corresponding to the above difference in phase. Factors such as the radius of a pitch circle of the outer pins (9), the eccentric amount between the external gear and the internal gear, the radius of each outer pin (9), the speed reduction ratio, and the difference in the number of teeth are given a predetermined relationship therebetween, thereby providing a planetary speed-up and -down gearing in which a relative slippage speed in the meshing is reduced and thus a noise level is reduced with the difference in the number of teeth being three or more. Also, by keeping the radius of each outer pin constant and also keeping the number of the outer pins constant, a planetary speed-up and -down gearing is provided in which the same outer pins can be shared by three or more external gears.
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