Abstract: An electric power steering apparatus (1, 64) comprises a housing (10) for supporting a steer shaft (9) for axial slide movement, a speed reduction mechanism (23), and a motion converting mechanism (24, 76). The housing (10) includes a plurality of split housings (36, 37; 36, 37A, 70) connected to each other. The speed reduction mechanism (23) includes an output gear (22) surrounding the steer shaft (9). The motion converting mechanism (24, 76) includes a rotary sleeve (28) surrounding the steer shaft (9) and rotatable integrally with the output gear (22) and converts the rotation of the rotary sleeve (28) into axial movement of the steer shaft (9). The rotary sleeve (28) is rotatably supported by first and second bearings (30, 31) disposed on opposite sides of the output gear (22). The split housings (36, 37; 36, 37A, 70) include main split housings (37, 37A) rotatably supporting an input gear (21) and supporting the first and second bearings (30, 31).

Abstract: An electric power steering apparatus (1, 64) comprises a housing (10) for supporting a steer shaft (9) for axial slide movement, a speed reduction mechanism (23), and a motion converting mechanism (24, 76). The housing (10) includes a plurality of split housings (36, 37; 36, 37A, 70) connected to each other. The speed reduction mechanism (23) includes an output gear (22) surrounding the steer shaft (9). The motion converting mechanism (24, 76) includes a rotary sleeve (28) surrounding the steer shaft (9) and rotatable integrally with the output gear (22) and converts the rotation of the rotary sleeve (28) into axial movement of the steer shaft (9). The rotary sleeve (28) is rotatably supported by first and second bearings (30, 31) disposed on opposite sides of the output gear (22). The split housings (36, 37; 36, 37A, 70) include main split housings (37, 37A) rotatably supporting an input gear (21) and supporting the first and second bearings (30, 31).

Abstract: A nut member which is rotated by power transmission from a motor in a rack housing is supported by a thrust bearing fitted and fixed in a first housing having an integrally formed fixing section for fastening to a vehicle body so that the nut member cannot move in both directions along an axial direction. Thrust loads applied in both directions to the nut member with the conversion of rotation into movement of a steering shaft in an axial direction are carried by the first housing through the thrust bearing. The structure of the connection section of the first housing and second housing is simplified, and the housing is fixed in a stable manner to prevent deterioration in steering feeling.

Abstract: An electric power steering apparatus comprises a rack shaft movable in the axial direction. The rack shaft is meshed with a pinion rotated in response to the operation of a steering member. The rotation of the output shaft in an electric motor is decelerated by first and second gears which are meshed with each other. A motion conversion mechanism for converting the rotation of the second gear into the axial movement of the rack shaft comprises a rotating cylinder rotated in synchronization with the second gear and a screw shaft. The screw shaft is integrally provided coaxially with the rack shaft and is screwed into the rotating cylinder through a rolling member. A screw groove in the screw shaft and the teeth in the first gear are twisted in the same direction.

Abstract: An electric power steering apparatus comprises a speed reduction mechanism for decelerating the rotation of an output shaft in an electric motor for steering assist. The speed reduction mechanism comprises a driving gear connected to the output shaft in the electric motor and a driven gear meshed with the driving gear. One of respective tooth sections in the driving gear and the driven gear includes a tooth section formed of a material having a relatively low hardness, and the other tooth section includes a tooth section formed of a material having a relatively high hardness. The profile of the tooth section formed of the material having a relatively low hardness is shifted in the direction in which the thickness at the root of the teeth of the tooth section is increased. The profile of the tooth section formed of the material having a relatively high hardness is shifted in the direction in which the thickness at the root of the teeth of the tooth section is decreased.

Abstract: An electric power steering apparatus comprises a rack shaft movable in the axial direction. The rack shaft is meshed with a pinion rotated in response to the operation of a steering member. The rotation of the output shaft in an electric motor is decelerated by first and second gears which are meshed with each other. A motion conversion mechanism for converting the rotation of the second gear into the axial movement of the rack shaft comprises a rotating cylinder rotated in synchronization with the second gear and a screw shaft. The screw shaft is integrally provided coaxially with the rack shaft and is screwed into the rotating cylinder through a rolling member. A screw groove in the screw shaft and the teeth in the first gear are twisted in the same direction.

Abstract: An electric power steering apparatus comprises a speed reduction mechanism for decelerating the rotation of an output shaft in an electric motor for steering assist. The speed reduction mechanism comprises a driving gear connected to the output shaft in the electric motor and a driven gear meshed with the driving gear. One of respective tooth sections in the driving gear and the driven gear includes a tooth section formed of a material having a relatively low hardness, and the other tooth section includes a tooth section formed of a material having a relatively high hardness. The profile of the tooth section formed of the material having a relatively low hardness is shifted in the direction in which the thickness at the root of the teeth of the tooth section is increased. The profile of the tooth section formed of the material having a relatively high hardness is shifted in the direction in which the thickness at the root of the teeth of the tooth section is decreased.

Abstract: A nut member which is rotated by power transmission from a motor in a rack housing is supported by a thrust bearing fitted and fixed in a first housing having an integrally formed fixing section for fastening to a vehicle body so that the nut member cannot move in both directions along an axial direction. Thrust loads applied in both directions to the nut member with the conversion of rotation into movement of a steering shaft in an axial direction are carried by the first housing through the thrust bearing. The structure of the connection section of the first housing and second housing is simplified, and the housing is fixed in a stable manner to prevent deterioration in steering feeling.