GEARING WITHOUT BACKLASH FOR ELECTRIC POWER STEERING

摘要

A steering gear system for an electric power steering system includes a motor, a gearing mechanism driven by the motor, a drive gear in mechanical communication with the gearing mechanism, a ball nut driven by the drive gear, and a rack laterally positioned through the ball nut and configured to translate the ball nut upon rotation thereof. The gearing mechanism includes a pinion and a sub-pinion in mechanical communication with each other held together but urged apart by a resilient member disposed therebetween. The pinion is urged away from a rotor shaft of the motor by at least one spring to compensate for angular motion of the pinion on the rotor shaft. Helical gear threads disposed on the pinion and sub-pinion are configured to engage corresponding threads on the drive gear. The resilient member forces the flanks of the threads on the pinion and the sub-pinion to remain in contact with corresponding threads on the drive gear regardless of the direction of rotation of the pinion/sub-pinion assembly.