Planetary gear transmission system

摘要

A planetary gear transmission gear system comprises a main planetary gear train composed of a main sun gear, a main ring gear, and main planet gears. The main sun gear is driven by an input rotary shaft to rotate. A sub planetary gear train is included to have a sub sun gear, a sub ring gear, and sub planet gears, and has a different gear ratio from the main planetary gear train. The sub sun gear is connected to rotate together with the main sun gear. A common carrier supporting the main and sub planet gears is rotatable about a common center axis and is drivingly connected to rotate an output shaft. A lock mechanism releasably fixes the main ring gear in order to allow the main planet gears to rotate about the center axis as the main sun gear rotates with the main ring gear fixed. A one-way clutch is connected to permit the sub ring gear to rotate in a first direction and to prohibit the sub ring gear from rotating in a second direction opposite to the first direction. The first direction is selected to be a direction in which the sub ring gear is permitted to rotate while the carrier rotates with the main ring gear fixed by the lock mechanism such that the sub ring gear is locked in the second direction after the main ring gear is released, thereby permitting the carrier to continue rotating at a speed reduction ratio different than when the main ring gear is fixed.