An electric power-steering device has a speed-reducing mechanism (17) for reducing the speed of an output shaft (16) of an electric motor (15). The speed-reducing mechanism (17) has an internal gear (39) engaged and rotated with the output shaft (16) and an external gear (40) with which the internal gear (39) internally meshes. A drive pulley (41) rotatable together with the external gear (40) and a driven pulley (42) provided so as to surround a steering shaft are connected by an endless belt (43). Speed reduction is obtained by the internal gear (39) and the external gear (40), and the speed-reducing mechanism (17) as a whole achieves a high reduction ratio without greatly reducing the diameter of the drive pulley (41).

Electric power-steering device

Steering shaft reaction torque is estimated by steering shaft reaction torque-estimating means, and reference road surface reaction torque is estimated by reference road surface reaction torque-estimating means. After that, the obtained steering shaft reaction torque and reference road surface reaction torque are weighted. Based on the weighted result, aimed steering reaction torque is set by aimed steering reaction torque-producing means. The width and inclination of a hysteresis of the aimed steering reaction torque are each adjusted so that steering feeling is easily improved.

Steering control device

The system and method described herein can be used to reduce the effects of periodic vibrations in an electric power steering (EPS) system for a vehicle, particularly, those that can lead to smooth road shake (SRS), torsional nibble, and/or other undesirable conditions. According to an exemplary embodiment, an electric motor is used to purposely generate counter-acting vibrations in the EPS system to cancel out the periodic vibrations generated by the wheel assemblies or corners.

Reducing The Effects Of Vibrations In An Electric Power Steering (EPS) System

Methods and systems are provided for suppression of steering wheel vibrations generated by periodic disturbances in a vehicle steering system. An exemplary method reducing steering wheel vibrations caused by periodic disturbances involves determining a gross torque attributable to the periodic disturbances in the steering system, identifying a desired amount of suppression of the vibrations at the steering wheel, determining an offset torque based on the gross torque and the desired amount of suppression, and generating a motor command signal in a manner that is influenced by the offset torque. The motor drive command signal is provided to an electric motor coupled the steering wheel and/or the vehicle tires, and the motor drive command signal influences the torque applied by the motor to assist steering of the vehicle tires by the steering wheel in a manner that attenuates the vibrations communicated to the steering wheel by the desired amount.

Methods, systems and apparatus for steering wheel vibration reduction in electric power steering systems

In a control method for an electric power steering apparatus having a steering member, a steering mechanism, and a motor for assisting steering, a steering torque applied to a steering wheel is detected, frequency analysis is performed on the detected torque, and a determination is made as to whether or not a torque component having a frequency equal to or higher than a predetermined value is included in the result of the frequency analysis. When such a torque component is included in the frequency analysis result, a predetermined rotary torque is generated in a single direction.

Electric power steering apparatus and method for controlling same

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 15 a , 15 b acting when a target control value of the electric motor 6 is generated based on an output from the torque sensor 3 ; and means 15 c 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.

Eletric power steering system

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.

Method for producing electric power steering apparatus

PROBLEM TO BE SOLVED: To provide a motor-driven power steering gear capable of stably maintaining vehicle behaviors even if a road condition or the like changes, while securing a good steering feeling. SOLUTION: A normal steering torque operation part 12 calculates steering torque which includes a yaw rate γ and a predetermined relation as a normal steering torque Th* based on a detected steering angle δs and a detected vehicle speed value Vs. A torque/current conversion element 16 calculates a motor current corresponding to a variation ▵T with the normal steering torque Th* and the detected steering torque value Ths as a current target value Im*. A current control part 20 calculates a voltage command value Vm* by a proportional integration control calculation based on the current target value Im* and a variation ▵I from the detected value Im of a motor current. The voltage corresponding to the voltage command value Vm* is applied to a motor 6, thus the voltage corresponding to the current target value Im* passes though the motor 6. The motor 6 produces an assist torque Tm so that the detected steering torque value Ths is almost equal to the normal steering torque Th*. COPYRIGHT: (C)2004,JPO

Motor-driven power steering gear

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 0.8 and equal to or less than 1.5, a tooth depth is equal to or less than 2.4 times of the module, and a pressure angle is equal to or more than 14.5 degrees and equal to or less than 30 degrees, and a torsion angle is equal to or more than 0 degrees and equal to or less than 40 degrees.

Motor-driven power steering apparatus

An electric power steering system for assisting steering by imparting the power of an electric motor through a reduction gear mechanism to a steering mechanism extending from a steering member to a steering wheel At the meshing part of gears on the motor power transmitting passage from the motor through the reduction gear mechanism to the steering mechanism, grease (viscous body) having viscosity constant C≥08Jωp is provided, where J is inertia of the motor and ωp is the resonance angular frequency of the steering mechanism including the motor and the reduction gear mechanism Thus, it is possible to suppress generation of rattling noise resulting from the vibration system including the reduction gear mechanism and the motor and lowering of steering feeling

Katsutoshi Nishizaki

Papers

Eletric power steering system

Method for producing electric power steering apparatus

Motor-driven power steering gear

Motor-driven power steering apparatus

Electric motor power steering system