BELT SPEED REDUCER FOR ELECTRIC POWER STEERING DEVICE AND ELECTRIC POWER STEERING DEVICE

摘要

A belt speed reducer for an electric power steering device, having a drive pulley with first helical teeth, a follower pulley with second helical teeth, and a drive belt with third helical teeth. A helix angle (beta) of each of the helical teeth and friction coefficient (mu) between the first or second helical teeth and the third helical teeth has a relationship of tanbeta < mu. In an electric power steering device, a backlash between meshing gears of a speed reducer is adjusted or tension of a belt of a speed reducer is adjusted.