Patent ID: 7118507
Filing Date: 2006-10-10
Classification: F16H

Abstract:
1. An automatic reduction-ratio changing apparatus arranged between a rotary driving source and an actuator, for automatically switching a speed reduction ratio of a displaceable member of said actuator which is displaced reciprocally along an outward route and along a homeward route by a rotary driving force of said rotary driving source, said automatic reduction-ratio changing apparatus comprising: a planetary gear mechanism which has an input shaft connected to said rotary driving source and an output shaft connected to said actuator and which includes a sun gear, one or more planet gears, and an internal gear that are meshed with each other; a lock mechanism which stops rotation of said internal gear to lock said internal gear by rotating said internal gear having been rotated in the same direction of rotation as that of said sun gear to be rotated in a direction different from that of said sun gear when a load, which exceeds a preset predetermined torque, is applied from said actuator to said internal gear via said output shaft; and a lock release mechanism which automatically switches said speed reduction ratio transmitted from said output shaft to said displaceable member of said actuator by releasing said internal gear from a locked state by reversing said sun gear under a driving action of said rotary driving source when said displaceable member of said actuator switches from being displaced along said outward route to being displaced along said homeward route.