Patent ID: 7985157
Filing Date: 2011-07-26
Classification: G03B

Abstract:
1. A decelerating device, comprising: a fixed shaft; a tube, disposed around the fixed shaft and adapted to rotate about the fixed shaft, wherein the tube has a plurality of internal teeth; a first transmission element, having a fixed portion fixed at the fixed shaft and at least one first planetary gear revolvably disposed at the fixed portion, wherein the internal teeth of the tube are geared to the first planetary gear; and a driven element, having a wheel, a first sun gear fixed at the wheel and a plurality of first balls, wherein the first sun gear and the wheel are revolvably disposed at the fixed shaft and in the tube, the first planetary gear is adapted to drive the first sun gear, the wheel has a plurality of holes, each of the holes extends from an outer surface of the wheel facing the tube to the interior of the wheel to form a first cavity, and the first balls are disposed in the holes respectively; when the tube rotates along a first rotational direction, the driven element rotates along a second rotational direction opposite to the first rotational direction and each of the first balls is located in the corresponding first cavity; when the tube rotates above a specific rotational speed along the second rotational direction, the driven element rotates along the first rotational direction and each of the first balls is exposed outside the outer surface of the wheel and rubs against the tube.