Patent ID: 7588120

Claim:
An electric power steering apparatus using a coated pulley, comprising: a pinion shaft coupled to a shaft of a steering wheel and having teeth formed on the pinion shaft; a rack shaft having teeth formed in one end thereof and a ball screw formed in the other end thereof, the teeth of the rack shaft being meshed with the teeth of the pinion shaft; a ball nut provided on the ball screw through a plurality of balls interposed between the ball nut and the ball screw; a first pulley coupled to the ball nut to cooperate therewith; a torque sensor for sensing a torque generated from the steering wheel; an electric motor for generating a steering assisting force according to a signal from the torque sensor; a second pulley installed to one end of the electric motor; a belt connecting the first pulley and the second pulley to each other to transmit the steering assisting force generated from the electric motor to the ball nut; and a coating layer formed on an outer surface of the first or second pulley, the coating layer having a composition ratio of molybdenum sulfide of 10 to 90 wt %, antimony trioxide of 5 to 10 wt %, antirust agent of 1 to 5 wt %, auxiliary lubricant of 1 to 5 wt % and organic adhesive of 1 to 3 wt % dispersed in a solvent of 1 to 10 wt %.