| 摘要 |
In a differential planetary gear apparatus according to the present invention, a first shaft (25) and a second shaft (26) are rotatably supported in a casing (20). A sun gear (36) is fixed to the first shaft (25). A fixed internal gear (24) located in the casing (20) is arranged concentric with the sun gear (36). A rotary internal gear (34) connected to the second shaft (26) is arranged coaxially with the fixed internal gear (24), and has the difference M in the number of the teeth with respect to the number of the teeth of the fixed, internal gear (24). N (M NOTEQUAL N, N NOTEQUAL 1) planet gears (37) which revolve around the sun gear (36), are disposed at an equal intervals circumferentially. Each planet gear (37) has a first portion (C), engaged with the fixed internal gear (24), and a second portion (D), engaged with the rotary internal gear (34). Either one of the first and second portions (C and D) of planet gear (37) is engaged with the sun gear (36). When the number of planet gears (37) is designated circumferentially by i = 1, 2, ..., N, the phase of the teeth of the first portion (C) of the i-th planet gear (37) is shifted in period of {(i-1)M}/N with respect to that of the teeth of the second portion (D). Thus, the phase of the teeth of the first portion (C) can be shifted in response to the phase of the spaces of the fixed internal gear (24). Thus, if at least one of the internal gears (34) satisfies the assembling condition, the number of the teeth of the other internal gear (24) can be freely selected, irrespective of the number of the planet gears (37). In other words, the number of teeth of the internal gears (24 and 34) and the speed ratio can be freely selected, irrespective of the number of planet gears (37). |
