A speed reducer according to one aspect of the present disclosure includes an input rotating body, a speed reducing mechanism unit, and a tubular case. The speed reducer is rotatable when acted upon by power fed from a drive device. The speed reducing mechanism unit reduces a speed of rotation of the input rotating body. The tubular case covers an outer surface of the speed reducing mechanism unit and rotates when acted upon by speed-reduced power from the speed reducing mechanism unit. An output arm is formed integrally with the tubular case, the output arm extending radially outward from an outer peripheral surface of the tubular case and configured to transmit a manipulating force to an outside.

A linear electric actuator for steering systems includes: a casing, an electric motor, housed in the casing, which is provided with a stator and a hollow rotor internally concentric to the stator, a holder nut internally fixed to the rotor, and a stem having a thread coupled to the holder nut. The stem includes a first portion provided with a surface treatment, which projects outside the casing, and a second portion without said surface treatment, which is contained inside the casing and in which the thread is obtained.

An electric power steering apparatus is provided, including a casing; a steering shaft, disposed in the casing in an axially reciprocal manner and extending from two ends of the casing, and the body thereof having a rack portion and a screw portion; a planetary roller nut, assembled in the casing and screwed to the screw portion; a motor, controlled by the ECU, disposed in the casing, and having an external rotor, and the external rotor being coupled to the planetary roller nut to drive the motor to rotate, further driving the steering shaft to reciprocate in the casing; a first waterproof ring, provided between the planetary roller nut and the casing, and a second waterproof ring, placed between the planetary roller nut and the hollow stator of the motor, thus forming an airtight and waterproof efficacy for the motor to prevent the motor from losing power.

A utility vehicle steering system includes a steering gear for transmitting a manual torque from a steering wheel to a steering drop arm. An electric motor provides an auxiliary torque for the steering boost, which is provided exclusively electrically over the entire operating range of the steering system. An input shaft and an output shaft have axes of rotation that are skewed with respect to each other. A first gear device couples the input shaft to the output shaft. A second gear device has the electric motor connected to the input side and has at least one speed-reduction gear stage in the form of a coaxial gear with a high transmission ratio. The output side of the second gear device is coupled to the output shaft and its speed reduction gear stage, a coaxial gear with a high transmission ratio, is coaxial with the output shaft.

A steering device according to one embodiment includes: an input device including an input shaft to which rotation associated with operation is transmitted, and a transmission shaft that is disposed orthogonal to the input shaft and rotates in conjunction with the input shaft; a reducer receiving a rotational drive force from the input device and outputting a rotational force about a rotational axis with a reduced rotational speed and an increased torque; a motor providing a rotational auxiliary force to the reducer in a direction that augments the rotational driving force; and an output arm coupled to the reducer and rotating about the rotational axis in a predetermined angular range by the rotational force outputted by the reducer. The input device is disposed on one side of the reducer. The motor is disposed adjacent to a direction orthogonal to the transmission shaft and on the one side of the reducer.

Provided is an electric actuator (1), including: a motor part (A); and a motion conversion mechanism part (B). The motion conversion mechanism part (B) includes: a screw shaft (33); a nut member (32); and a planetary gear speed reducer (10) configured to reduce a speed of rotation of the rotor (24) and output the rotation. The screw shaft (33) is configured to advance toward one side in an axial direction or retreat toward another side in the axial direction in accordance with a rotation direction of the nut member (32), and the nut member (32) is arranged on an inner periphery of the rotor (24), and is coupled to a planetary gear carrier (43), which is an output member of the planetary gear speed reducer (10), so as to be capable of transmitting torque.

Provided is a steering system including a low-cost rolling bearing with high supporting rigidity wherein generation of rattling noise during operation is prevented. A steering system includes a housing, a steered shaft, a ball screw device, a motor, a drive force transmission mechanism, and a bearing device. A ball nut portion is formed in a first range, and the bearing device supports a nut on the housing in a second range. The bearing device includes an outer ring, a first inner ring portion formed as a part of the nut in the second range, a second inner ring fitted to the outer peripheral surface of the nut in the second range, a plurality of bearing balls, and an enlarged diameter portion formed as a part of the nut in the second range.

A belt drive has a drive gear, an output gear, a tensioning gear, and at least two belts. Each belt partly loops the drive gear and the output gear, and a strand of each belt partly loops the tensioning gear. A strand of a first belt loops the tensioning gear in one circumferential direction. This strand extends from the drive gear to the output gear. A strand of a second belt loops the tensioning gear in the other circumferential direction. This strand extends from the drive gear to the output gear. This belt drive achieves a large looping angle for the drive gear and the output gear, and correspondingly, a large transmission power. Additionally, the effect of the other belt enables a belt self-tensioning function which is independent of the rotational direction. Guiding the belts in this manner enables omission of an additional mounting of the tensioning gear.

According to the embodiments of the present invention, the overall size reduction allows installation space to be advantageously secured, reduction in noise generated during operation improves the comfort of the driver, and the strength and stability of the connective structure between parts can be increased and power transmission can be more effective.

Implementations of a steering system may include: an arm configured to couple with a tie rod, the arm coupled through a journal bearing; a thrust bearing coupled to the journal bearing and to a nut; a screw rotatably coupled to an inverted planetary roller screw, the screw coupled with the nut; a rotor coupled to the nut and to a housing, the housing configured to be fixedly coupled to a frame; and a stator coupled to the housing and around the rotor and the inverted planetary roller screw where the stator is electrically coupled to a power source.