Patent ID: 7475577

Claim:
An electric steering lock system comprising: a casing mounted to a steering column; a locking member slidably supported in the casing between a position for engaging the casing with a steering shaft and a position for disengaging the casing from the steering shaft; a rotation member for operating the locking member to slide in response to rotation thereof; an electric motor; and a planetary gear mechanism for reducing the rotation speed of the electric motor and transmitting the rotation speed to the rotation member, wherein the planetary gear mechanism includes: a first sun gear coaxially coupled to an output shaft of the electric motor in a relatively non-rotatable manner; a plurality of first planetary gears meshed with the first sun gear; a ring gear which is fixed to the casing and has inner teeth to be meshed with the first planetary gears; a first carrier for rotatably supporting the plurality of the first planetary gears; a second sun gear disposed coaxially with the first sun gear and coupled to the first carrier in a relatively non-rotatable manner; a plurality of second planetary gears meshed with the second sun gear and the inner teeth; a second carrier which rotatably supports the second planetary gears and is coupled to one end of the rotation member in a relatively non-rotatable manner; and a coaxial shaft whose opposite ends are coaxially coupled to the first sun gear and the rotation member respectively in a relatively rotatable manner, the first carrier and the second sun gear being supported on the coaxial shaft in a relatively rotatable manner, and wherein the first sun gear encompasses adjoining ends of the output shaft and coaxial shaft.