Abstract: An electric power steering apparatus for a vehicle includes a rack shaft having a rack of gear teeth formed at one end portion thereof and an externally threaded screw formed at a portion thereof excluding the toothed one end portion, a pinion meshing with the rack, a ball-screw mechanism having a nut threadedly engaged with the screw via balls, and an electric motor having a hollow motor shaft extending around the rack shaft and connected to the nut such that an assist torque generated by the electric motor is transmitted from the motor shaft via the nut to the rack shaft. The nut is disposed between the rack and the electric motor. This arrangement ensures that the electric motor and the electric power steering apparatus can be assembled easily and efficiently.

Abstract: An electric power steering apparatus for a vehicle includes a rack shaft having a rack of gear teeth formed at one end portion thereof and an externally threaded screw formed at a portion thereof excluding the toothed one end portion, a pinion meshing with the rack, a ball-screw mechanism having a nut threadedly engaged with the screw via balls, and an electric motor having a hollow motor shaft extending around the rack shaft and connected to the nut such that an assist torque generated by the electric motor is transmitted from the motor shaft via the nut to the rack shaft. The nut is disposed between the rack and the electric motor. This arrangement ensures that the electric motor and the electric power steering apparatus can be assembled easily and efficiently.

Abstract: An electric power steering apparatus for applying an auxiliary torque generated in proportion to a steering torque, to a rack shaft to thereby reduce the steering torque. The rack shaft has at one end thereof rack teeth for meshing with a pinion. A rack guide mechanism is provided at the rack shaft one end oppositely from the rack teeth, for urging the rack shaft to the pinion. At the other end of the rack shaft, a screw portion and a ball screw mechanism are provided. A bush is provided for supporting an intermediate portion of the rack shaft to thereby restrict the bending of the intermediate portion beyond a predetermined value when an external force is applied to the rack shaft ends thereby bending the rack shaft intermediate portion. As a result, the vibration of the rack shaft and hence a steering wheel can be minimized.

Abstract: An electric motor used in an electric type power steering apparatus and the like, wherein a magnetic field unit outer casing 14 for encasing a magnetic field unit 7 comprising magnets 5 and an armature 6, is formed integral and concentric with a motor yoke 3, and a power supply unit outer casing 15 for encasing a commutator 22 and brushes 27 of a power supply unit 8, having a protruding portion 15a protruding from an axially concentric outer peripheral face thereof arranged eccentric to the magnetic field unit outer casing 14, is formed integral with the motor yoke 3. As a result, the influence of shock from the outside is suppressed, and accommodating space for the power supply unit ensured, so that long motor life is possible.

Abstract: An electrically operated power steering apparatus has a housing, a pinion rotatably supported in the housing, the pinion being adapted to be connected to a steering shaft, a rack shaft axially movably disposed in the housing and held in mesh with the pinion, an electric motor disposed coaxially around the rack in the housing, and a ball-and-nut mechanism disposed on the rack shaft in the housing for transmitting a torque produced by the electric motor as an axial displacement to the rack shaft. The electric motor has a stator fixedly mounted in the housing and a rotor rotatably supported in the housing by a pair of bearings mounted on respective opposite ends of the rotor, the ball-and-nut mechanism being coupled to the rotor. A rack guide is disposed in the housing behind the pinion remotely from the ball-and-nut mechanism and held in sliding contact with the rack shaft. The rack shaft is axially slidably supported in the housing by the ball-and-nut mechanism and the rack guide.

Abstract: An electrically assisted power steering system for a motor vehicle includes a housing, a shaft slidably supported in the housing, a ball-and-nut mechanism operatively mounted on the shaft, and an electric motor mounted in the housing for transmitting rotary force from the electric motor through the ball-and-nut mechanism to the shaft. The ball-and-nut mechanism including a nut assembly disposed around the shaft and having one end rockably and rotatably supported in the housing by a four-point contact bearing or an automatic aligning bearing, and a plurality of balls movably held between an opposite end of the nut assembly and a screw groove defined in the shaft.

Abstract: An electrically operated power steering apparatus having an electric motor for producing forces to assist in axially moving a rack shaft having rack teeth held in mesh with a pinion mounted on an end of a steering shaft with a steering wheel mounted thereon. The electric motor and the rack shaft are accommodated in a housing assembly which comprise a first housing and a second housing which are separate from and fastened to each other in an axial direction of the rack shaft. The second housing comprises a smaller-diameter portion, a medium-diameter portion, and a larger-diameter portion which are axially successively joined by tapered portions. The electric motor has a stator fixed to an inner surface of the larger-diameter portion and a rotor rotatably disposed around the rack shaft in the larger-diameter portion.

Abstract: A motor-driven power steering device includes an electric motor for generating assistive torque which is applied through a ball screw mechanism to a steering gear mechanism to reduce manual steering forces applied by the driver to steer a motor vehicle. The motor-driven power steering device comprises a rack-and-pinion steering gear mechanism for converting the rotation of a pinion shaft to axial movement of a rack shaft, an electric motor for generating assistive torque to be applied to the rack-and-pinion steering gear mechanism, and a ball screw mechanism for converting the assistive torque from the motor to the axial movement of the rack shaft.