Abstract: A flywheel includes a wheel ring and a hub ring fitted into the wheel ring. A hub ring main body of the hub ring pressure-contacts an inner periphery of the wheel ring while the flywheel is rotating. The pressure contact of the hub ring with the inner periphery of the wheel ring allows compressive stress applied to the wheel ring in a radial direction to cancel a portion of tensile stress acting in the wheel ring in the radial direction. As a result, the stress in the wheel ring in the radial direction decreases.

Abstract: An electric power steering system is provided which is capable of providing a favorable steering feeling without using compensation logics such as of inertia compensation and friction compensation. The electric power steering system includes road-noise suppression control means (213) for controlling a steering assist motor (9) in a manner to damp torque transmission in a higher frequency region representing road noises than a frequency region representing road information. A friction value of a steering mechanism (A) is decreased enough to allow the intrinsic vibrations of the steering mechanism (A) to appear. Rotor inertia of the steering assist motor (9) is set to a value small enough to allow the frequencies of the intrinsic vibrations to be present in the frequency region where the torque transmission is damped by the road-noise suppression control means (213).

Abstract: The invention provides a motor-driven power steering apparatus which can achieve a predetermined speed reduction ratio even in the case that the motor-driven power steering apparatus is constituted by a pair of spur gears or helical gears, and can secure a sufficient gear strength on the basis of a simple structure. In a motor-driven power steering apparatus in which a rotating torque of an electric motor (7) is transmitted to a steering shaft by a drive gear (6) provided in an output shaft of the electric motor (7) and a driven gear (5) provided in the steering shaft, and a speed reduction ratio is equal to or more than 3, the steering shaft and the output shaft of the electric motor (7) are arranged in almost parallel, a center distance between both the shafts is equal to or more than 35 mm and equal to or less than 90 mm, and the drive gear (6) is configured such that a number of teeth is equal to or more than 6 and equal to or less than 15, a module is equal to or more than 0.

Abstract: A reduction gear unit capable of reducing vibrations caused by gear rattle, while permitting some degree of backlash in a pair of gears, is provided. A reduction gear unit is so configured that a pinion shaft and a main gear shaft are disposed in parallel to each other, and a pinion 1 mounted on the pinion shaft and a main gear 2 mounted on the main gear shaft are arranged to mesh with each other, so as to transmit a rotation of the pinion shaft to the main gear shaft, and includes a housing 11 that encloses the pinion 1 and the main gear 2, where the housing 11 has an inner surface whose width, in a cross section perpendicular to an axial direction of the pinion shaft and the main gear shaft, perpendicular to an imaginary line that connects centers of the pinion shaft and the main gear shaft evenly increases from a pinion side toward a main gear side between ends of arcuate regions respectively enclosing the main gear and the pinion.

Abstract: A second housing is aligned with a first housing at a predetermined position using positioning means that determines the mounting position of the housing with respect to the first housing at the predetermined position; steering shaft supporting sections and output shaft supporting sections are provided in the first housing and the second housing respectively while the housings being mounted using screws or the like; the second housing is removed temporarily from the first housing; a steering shaft and an output shaft are supported using the steering shaft supporting sections and the output shaft supporting sections; and the second housing is aligned again with the first housing at the predetermined position using the positioning means and mounted.

Abstract: In an electric power steering system providing steering assist by applying a power of an electric motor to a steering mechanism via a reduction mechanism, the steering mechanism extending from a steering member to dirigible wheels, a grease (viscous material) is applied to a meshing engagement portion between teeth portions disposed on a motor-power transmission path extending from the electric motor to the steering mechanism via the reduction mechanism, the grease having a viscosity constant C satisfying 0.8 J?p?C where J denotes the inertia of the electric motor, and cop denotes the resonant angular frequency of the steering mechanism including the electric motor and the reduction mechanism. This provides for the prevention of the occurrence of rattling noises caused by a vibration system including the reduction mechanism and the electric motor and the degradation of the steering feeling.

Abstract: There are provided a high-order current distortion compensator which uses rotational position information on an electric motor and a target current value of the electric motor for deciding a compensation value for current high-order-component for canceling torque ripple caused by predetermined high-order components of a current flowing through the motor, and a correction portion which corrects the target current value by using the compensation value supplied from the high-order current distortion compensator. A feedback controller provides feedback control of the electric motor based on the target current value corrected by the correction portion. Thus is suppressed the torque ripple caused by the predetermined high-order components, whereby the degradation of steering feeling is reduced.

Abstract: An erroneous assembling preventing tool for a universal joint prevents a shaft from being fixed to a cylindrical section of a yoke main body of the universal joint by fastening a bolt in a state where the shaft is not inserted into a normal position of an axial direction of the cylindrical section. The erroneous assembling preventing tool comprises a fixing section fixed to the yoke main body, a prevention section arranged between first and second tabs of the yoke main body, and a driving section for driving a prevention section. The prevention section is displaceable to a prevention position at which an end of the bolt can be prevented from being inserted through a screw hole of the second tab of the yoke and a prevention release position. The driving section displaces the prevention section to the prevention release position when it is pressed by an end of the shaft inserted into the normal position of the axial direction of the cylindrical section.

Abstract: A second housing is aligned with a first housing at a predetermined position using positioning means that determines the mounting position of the housing with respect to the first housing at the predetermined position; steering shaft supporting sections and output shaft supporting sections are provided in the first housing and the second housing respectively while the housings being mounted using screws or the like; the second housing is removed temporarily from the first housing; a steering shaft and an output shaft are supported using the steering shaft supporting sections and the output shaft supporting sections; and the second housing is aligned again with the first housing at the predetermined position using the positioning means and mounted.

Abstract: An electric power steering assembly includes an electric motor, a reduction mechanism for reducing the speed of an output rotation of the electric motor, and a reduction-mechanism housing accommodating therein the reduction mechanism. The electric motor includes: an output shaft rotatably supported by the reduction-mechanism housing, a motor housing formed integrally with the reduction-mechanism housing, a rotor, and a stator assembly accommodated in an annular space defined between the rotor and the motor housing. When the stator assembly is assembled in the annular space via an opening at an end portion of the motor housing, a guided portion on an outside circumference of a stator yoke is guided by a guide portion on an inside circumference of the motor housing.

Abstract: An electric power steering system is provided which is capable of providing a favorable steering feeling without using compensation logics such as of inertia compensation and friction compensation. The electric power steering system includes road-noise suppression control means (213) for controlling a steering assist motor (9) in a manner to damp torque transmission in a higher frequency region representing road noises than a frequency region representing road information. A friction value of a steering mechanism (A) is decreased enough to allow the intrinsic vibrations of the steering mechanism (A) to appear. Rotor inertia of the steering assist motor (9) is set to a value small enough to allow the frequencies of the intrinsic vibrations to be present in the frequency region where the torque transmission is damped by the road-noise suppression control means (213).

Abstract: The invention provides a motor-driven power steering apparatus which can achieve a predetermined speed reduction ratio even in the case that the motor-driven power steering apparatus is constituted by a pair of spur gears or helical gears, and can secure a sufficient gear strength on the basis of a simple structure. In a motor-driven power steering apparatus in which a rotating torque of an electric motor (7) is transmitted to a steering shaft by a drive gear (6) provided in an output shaft of the electric motor (7) and a driven gear (5) provided in the steering shaft, and a speed reduction ratio is equal to or more than 3, the steering shaft and the output shaft of the electric motor (7) are arranged in almost parallel, a center distance between both the shafts is equal to or more than 35 mm and equal to or less than 90 mm, and the drive gear (6) is configured such that a number of teeth is equal to or more than 6 and equal to or less than 15, a module is equal to or more than 0.

Abstract: In a current control system for a cylindrical permanent magnet synchronous motor as the drive source of an electric power steering apparatus, proportional gain Kdp and integral gain Kdi of a d-axis current PI control portion 126 are respectively set to K1·Ld and K1·Rd on the basis of d-axis inductance Ld and d-axis resistance Rd of the motor. Further, proportional gain Kqp and integral gain Kqi of a q-axis current PI control portion 128 are respectively set to K2·Lq and K2·Rq on the basis of q-axis inductance Lq and q-axis resistance Rq of the motor (K1 and K2 are optional coefficients). In this case, both of the d-axis resistance Rd and the q-axis resistance Rq have values resulting from adding the external resistance R? including wiring resistance to the internal resistance R of the motor.

Abstract: An electric power steering assembly includes an electric motor, a reduction mechanism for reducing the speed of an output rotation of the electric motor, and a reduction-mechanism housing accommodating therein the reduction mechanism. The electric motor includes: an output shaft rotatably supported by the reduction-mechanism housing, a motor housing formed integrally with the reduction-mechanism housing, a rotor, and a stator assembly accommodated in an annular space defined between the rotor and the motor housing. When the stator assembly is assembled in the annular space via an opening at an end portion of the motor housing, a guided portion on an outside circumference of a stator yoke is guided by a guide portion on an inside circumference of the motor housing.

Abstract: An electric power steering system causing an electric motor 6 to generate a steering assist force according to a steering torque, includes: a torque sensor 3 for detecting the steering torque; phase compensation means 15a, 15b acting when a target control value of the electric motor 6 is generated based on an output from the torque sensor 3; and means 15c for varying the characteristic of the phase compensation means depending upon whether a steering mode is steer with driving or steer without driving, whereby a loadless steering feeling due to phase lag is not encountered during driving even if vibrations during steer without driving are suppressed by a phase compensator.

Abstract: In an electric power steering system providing steering assist by applying a power of an electric motor to a steering mechanism via a reduction mechanism, the steering mechanism extending from a steering member to dirigible wheels, a grease (viscous material) is applied to a meshing engagement portion between teeth portions disposed on a motor-power transmission path extending from the electric motor to the steering mechanism via the reduction mechanism, the grease having a viscosity constant C satisfying 0.8 J?p?C where J denotes the inertia of the electric motor, and cop denotes the resonant angular frequency of the steering mechanism including the electric motor and the reduction mechanism. This provides for the prevention of the occurrence of rattling noises caused by a vibration system including the reduction mechanism and the electric motor and the degradation of the steering feeling.

Abstract: An electric power steering system includes: an electric motor 6 for generating a steering assist force; a torque sensor 3 for detecting a steering torque; means 10 for generating a control target value for the electric motor 6 according to the detected steering torque; and means 28 for providing a non-interactive control of the electric motor. The system further includes a filter 12 which acts in the process of generating the control target value for the electric motor based on the steering toque. The filter 12 includes: a phase compensator 13 for decreasing a resonant peak gain of the system; and an LPF 12 for decreasing a second peak at a higher frequency than that of the resonant peak. The system is not degraded in the characteristics thereof even though the system provides a non-interactive control for ensuring followability of motor control.

Abstract: There are provided a high-order current distortion compensator which uses rotational position information on an electric motor and a target current value of the electric motor for deciding a compensation value for current high-order-component for canceling torque ripple caused by predetermined high-order components of a current flowing through the motor, and a correction portion which corrects the target current value by using the compensation value supplied from the high-order current distortion compensator. A feedback controller provides feedback control of the electric motor based on the target current value corrected by the correction portion. Thus is suppressed the torque ripple caused by the predetermined high-order components, whereby the degradation of steering feeling is reduced.

Abstract: A reduction gear unit capable of reducing vibrations caused by gear rattle, while permitting some degree of backlash in a pair of gears, is provided. A reduction gear unit is so configured that a pinion shaft and a main gear shaft are disposed in parallel to each other, and a pinion 1 mounted on the pinion shaft and a main gear 2 mounted on the main gear shaft are arranged to mesh with each other, so as to transmit a rotation of the pinion shaft to the main gear shaft, and includes a housing 11 that encloses the pinion 1 and the main gear 2, where the housing 11 has an inner surface whose width, in a cross section perpendicular to an axial direction of the pinion shaft and the main gear shaft, perpendicular to an imaginary line that connects centers of the pinion shaft and the main gear shaft evenly increases from a pinion side toward a main gear side between ends of arcuate regions respectively enclosing the main gear and the pinion.

Abstract: An erroneous assembling preventing tool for a universal joint prevents a shaft from being fixed to a cylindrical section of a yoke main body of the universal joint by fastening a bolt in a state where the shaft is not inserted into a normal position of an axial direction of the cylindrical section. The erroneous assembling preventing tool comprises a fixing section fixed to the yoke main body, a prevention section arranged between first and second tabs of the yoke main body, and a driving section for driving a prevention section. The prevention section is displaceable to a prevention position at which an end of the bolt can be prevented from being inserted through a screw hole of the second tab of the yoke and a prevention release position. The driving section displaces the prevention section to the prevention release position when it is pressed by an end of the shaft inserted into the normal position of the axial direction of the cylindrical section.