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. The ball screw mechanism has a screw shaft having a helical groove defined in an outer peripheral surface thereof and extending substantially parallel to the rack shaft, the screw shaft being receptive of the assistive torque generated by the motor, a nut having a helical groove defined in an inner peripheral surface thereof and disposed around the screw shaft, the nut being nonrotatably coupled to the rack shaft, and a plurality of balls disposed in and between the helical grooves of the screw shaft and the nut.
A steering system for a vehicle, the steering system includes a rack-independent actuator. The rack-independent actuator has component parts isolated from undesirable loads by two universal joints that isolate mechanical components of the actuator from transient loads that may be encountered by the rack or rack housing.
A power steering apparatus in which a motor for assisting steering force is mounted in such a manner that it is positioned substantially in parallel to a rack shaft of a rack-pinion type steering mechanism, and a planetary roller reduction device and a bevel gear connected directly thereto are mounted to the rotary shaft of the motor, coaxially with the motor. The speed of the turning force of the motor is reduced sufficiently and thus decelerated turning force is transmitted to the rack shaft, to permit compact disposing of the motor and the reduction device around the steering mechanism.
Power assistance mechanism for a rack and pinion steering gear assembly and an assembly which includes such mechanism includes a main rack and pinion steering gear 1 mounted on which is an auxiliary rack and pinion unit 9. The unit 9 includes an auxiliary rack bar 11, the rack of which engages with an auxiliary pinion in an auxiliary housing 10. The auxiliary pinion is rotatable by an electric motor 23 in the housing 10 to drive the auxiliary rack bar 11. The housing 10 is bolted through brackets 14 to the housing 2a of the main gear 1 while the auxiliary rack bar is coupled through a bracket 16 to the rack bar of the main gear 1. The electric motor 23 is controlled by a switch 27 in the steering input 7 to the pinion of the main steering gear 1 so that when the main rack bar is driven by rotation of the main pinion, the switch 27 is actuated to energize the electric motor and drive the auxiliary rack bar 11 in a sense appropriate to assist the displacement of the main rack bar.
The present invention relates to a hydraulic power steering system for automotive vehicles, having a steering gear with housing, steering shaft and steering rack, a hydraulic cylinder coupled to said steering rack, a pump and a steering valve, with all individual parts of the steering system forming a pre-assembly unit. This does not only permit a "just-in-time" delivery of the completely assembled, fluid-filled and tested system to the car maker, but also eases disassembly when the vehicle is junked. Thus, the power steering system according to this invention is inexpensive and can be recycled in an environment-friendly manner. The invention also includes a noise and vibration damping mounting arrangement. Still further, the invention includes an electric pump assembly.
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.
