SPEED REDUCER OF AN ELECTRIC POWER ASSIST STEERING SYSTEM AND AN ELECTRIC POWER ASSIST STEERING SYSTEM USING THE SAME CAPABLE OF ABSORBING VIBRATION AND NOISE CAUSED BY FRICTION AND ABRASION OF A WORM SHAFT AND A WORM WHEEL

摘要

PURPOSE: A speed reducer of an electric power assist steering system and an electric power assist steering system using the same are provided to reduce rattle noise caused by an increase in backlash due to friction and abrasion of a worm and a work wheel, or, an impact transferred through a wheel and a steering shaft from a road surface, and to increase the steering feel of a driver by reducing the notch feeling and rotational resistance of a worm shaft and a worm shaft bearing. ;CONSTITUTION: A speed reducer(300) of an electric power assist steering system comprises: a worm shaft bearing(257) coupled to two ends of a worm shaft(254) to support the rotation of the worm shaft to absorb vibration and noise caused by friction and abrasion when a worm shaft and a worm wheel(156) are run; a gear housing receiving a gear mechanism including the worm shaft, the worm shaft bearing and the worm wheel; a bearing support(310) supporting axially the worm shaft bearing coupled to an end of a connection of a motor shaft(305) of the worm shaft of the worm shaft bearing; and a damper(320) supported to a plug bolt(210) coupled to the gear housing to apply axial elastic force to the bearing support.;COPYRIGHT KIPO 2011