An electric power steering system. One example includes a steering control, a steering shaft connected to the steering control, a steering rack, a sensor configured to detect an operating parameter of the steering rack or an electric motor, and an electronic controller. In one example, the electronic controller is configured to receive data indicative of the operating parameter from the sensor, compare the data to a known characteristic curve, the known characteristic curve indicating potential damage to a component of the electric power steering system, and when the data matches the known characteristic curve, output an indication to a user that potential damage has occurred to the component of the electric power steering system.

A steering apparatus includes a turning shaft movable in the vehicle widthwise direction, a pinion shaft meshed with the turning shaft, a first housing that retains therein the turning shaft and the pinion shaft, a ball screw that transmits drive force generated by a drive source to the turning shaft, and a second housing that retains therein the ball screw. A retaining portion capable of storing water is provided at an inner circumferential surface of the second housing. A lower end surface of the retaining portion is located below at least a lower end surface of the ball screw. A first end portion of the retaining portion in the axial direction of the turning shaft is located between a belt member that links the ball screw with the drive source and a rack end stopper at the drive-source side.

An electric rotating machine has a first end frame and a second end frame for firmly supporting a stator between them in an axial direction of the electric rotating machine. An electronic control portion is mounted to a rear side of the first end frame. Multiple through-holes are formed at a radial-outer periphery of the second end frame. Each of multiple through-bolts is inserted into the respective through-holes from a side of the second end frame and screwed into the first end frame, to thereby firmly connect the first and the second end frames to each other.

An electric power steering device includes: an electric motor; a rack shaft configured to move axially; a conversion unit configured to convert rotational driving force of the moto into movement of the rack shaft; a first housing configured to cover a part of an outer surface of the rack shaft and including a first leg portion fixed to a vehicle; a second housing configured to cover a part of the outer surface of the rack shaft and including a fourth connecting portion covering the conversion unit and a second leg portion fixed to the vehicle; and an intermediate housing disposed between the first and second housings and configured to cover a part of the outer surface of the rack shaft 3 and including a motor support portion supporting the motor.

A steering device includes a steering rod that includes two ball screw parts, the steering rod being configured to steer a steerable wheel by moving linearly, two ball nuts respectively fastened to the two ball screw parts, two motors each configured to generate a drive force, two transmission mechanisms each including a toothed belt, the two transmission mechanisms being configured to transmit the drive force of each one of the two motors to a corresponding one of the ball nuts, two detectors configured to respectively detect rotation angles of the two motors, and a controller configured to control each of the two motors. The controller is configured to detect tooth jumping of the belts using the rotation angles of the two motors that are detected by the two detectors.

A rack housing and a reduction drive housing accommodate a ball screw mechanism and a reduction drive. Within the rack housing and the reduction drive housing, a gap is provided between the left end of a nut and the rack housing, and a gap is provided between the right end of the nut and the rack housing. A groove serving as a communication path in communication with the gaps on both axial sides of the nut is provided in the outer circumferential surface of the nut. The groove is provided so as to avoid a recirculation path provided in the nut. The groove is provided axially and rectilinearly from the end of the nut that is located on the side opposite to a flange, to the flange and is provided along the flange.

A production method of a ball screw device is provided. The ball screw device includes a ball screw portion, a ball nut, rolling balls, and a retainer. The production method of the ball screw device includes: a first preparation step of preparing a nut subassembly as a standard product; a second preparation step of preparing the ball screw portion in plurality by types as ranked products; a measuring step of measuring a relative displacement in a thrust direction between the standard product and each ranked product; a determination step of determining whether the displacement meets a displacement specification; a replacing step of, if the displacement does not meet the specification, replacing the ranked product with another ranked product; and an assembling step of, if the displacement meets the specification, assembling the standard product and the ranked product into the ball screw device.

Provided is a water detection system and an electric power steering apparatus capable of preventing or reducing complication of an apparatus with respect to a water detection system including a water detection element and a determination circuit positioned separately from each other. The water detection system includes a transmission-side unit provided in an apparatus mounted on a vehicle of the electric power steering apparatus and including a water detection element, and a reception-side unit spaced apart from the transmission-side unit and including a determination circuit. The transmission-side unit wirelessly transmits an output signal of the water detection element, and the reception-side unit receives the output signal wirelessly transmitted from the transmission-side unit.

A ball screw device and a steering system that include a retainer having more uniform stiffness are provided. Between a rack shaft and a ball screw nut, a cylindrical retainer having a plurality of retainer grooves that retain balls in a rollable manner is provided. Each retainer groove has two short inner surfaces that intersect the extending direction of the retainer groove and two long inner surfaces that intersect these short inner surfaces and extend along the extending direction of the retainer groove. In each of interior-angle portions where the short inner surfaces and the long inner surfaces intersect, a corner round surface is formed. The radius of the corner round surface is set to be smaller than one half of the width of the retainer groove.

A ball screw mechanism that allows a reduction in contact and friction between a retainer and a nut is provided. In a ball screw mechanism, a nut is threadedly engaged with a screw groove of a rack shaft through balls retained in a retainer groove of a retainer, and an axial force is applied to the rack shaft in accordance with rotation of the nut. The nut includes a uniform diameter portion having a uniform inside diameter and enlarged diameter portions each having an inside diameter larger than that of the uniform diameter portion. The enlarged diameter portions are provided at opposite axial ends of a region on an inner circumferential surface of the nut. The region faces the retainer groove and retainer ends adjoining to opposite axial ends of the retainer groove.