Honda Motor Co., Ltd.

Honda Giken Kogyo Kabushiki Kaisha

Yoshito Nakamura

Yasuo Shimizu

Shunichiro Sueyoshi

Koji Kobayashi

Tomohiro Hoshi

Nobuhiko Yoshimoto

Yuichi Fukuda

Mizuho Doi

Hitoshi Harada

Atsuhiko Yoneda

Yoshiki Noro

Yoshinobu Mukai

Shinzi Hironaka

Manabu Ikegaya

Kenichi Kirihara

A vehicle steering device includes: steering reaction force generation device having a steering wheel and a steering reaction force motor; steering reaction force motor resolver for detecting steering angle; turning device having a steering motor and capable of turning steered wheels, in a state being mechanically disconnected from the steering reaction force generation device; steering motor resolver for detecting turning angle; drive control section for performing drive control of the steering motor; and vehicle speed sensor for detecting the vehicle speed of vehicle. The drive control section performs drive control of the steering motor if vehicle speed exceeds vehicle speed threshold for the first time after ignition switch is turned on and if specific phase shift based on type and magnitude of phase shift occurs.

Vehicle steering device

For forming an annular magnetostrictive coat on an outer peripheral surface of a rotational shaft associated with a magnetostrictive torque sensor, a magnetostrictive-coat forming method comprises a step of fitting a cylindrical masking jig over the outer peripheral surface of the rotational shaft and securing the masking jig to the outer peripheral surface, a step of placing the rotational shaft in a plating tank to thereby form the magnetostrictive coat by plating on the outer peripheral surface, and a step of detaching the masking jig from the rotational shaft.

Magnetostrictive coat forming method, magnetostrictive torque sensor manufacturing method, and electric power steering apparatus employing the sensor

A magnetostrictive torque sensor includes first and second magnetostrictive films which are provided at a shaft and have different magnetic anisotropies; a first measurement coil and a second measurement coil which face the first magnetostrictive film; and a third measurement coil and a fourth measurement coil which face the second magnetostrictive film. A torque applied to the shaft is measured based on a variation in magnetic characteristics of the first and the second magnetostrictive films; and a failure of the magnetostrictive torque sensor is detected based on a first difference between output values from the first and the second measurement coils and a second difference between output values from the third and the fourth measurement coils. An electric steering system includes the magnetostrictive torque sensor for measuring a steering torque of the system; and an electric motor driven based on the measured magnetostrictive torque for steering the vehicle.

Magnetostrictive torque sensor system and electric steering system

For forming an annular magnetostrictive coat on an outer peripheral surface of a rotational shaft associated with a magnetostrictive torque sensor, a magnetostrictive coat forming method comprises a step of fitting a cylindrical masking jig over the outer peripheral surface of the rotational shaft and securing the masking jig to the outer peripheral surface, a step of placing the rotational shaft in a plating tank to thereby form the magnetostrictive coat by plating on the outer peripheral surface, and a step of detaching the masking jig from the rotational shaft.

Method for manufacturing a magnetostrictive torque sensor

Method for forming an annular magnetostrictive coat on an outer peripheral surface of a rotational shaft of magnetostrictive torque sensor

A magnetostriction-type torque sensorincludes a shaftformed of a magnetic material and provided with at least magnetostrictive filmsandexciting coils' and&#x2032; for exciting the magnetostrictive filmsandprovided on the shaftdetection coilsandfor detecting a change in a magnetic field; and yoke portionsrespectively provided around outer peripheries of the exciting coils&#x2032; and&#x2032; and the detection coilsandwherein a magnetic shield sectionformed of a magnetic material is provided around the outer peripheries of the yoke portions

Torque sensor

A rotational torque detection mechanism is provided, which includes a rotational shaft whose first end portion reaches outside the mechanism, a magnetostrictive membrane which is disposed on a surface of the rotational shaft and varies its magnetic permeability according to an amount and direction of rotational torque acting on the rotational shaft, an excitation circuit which is disposed to confront the rotational shaft so as to excite the magnetostrictive membrane and a detection circuit which is disposed to confront the rotational shaft so as to electrically detect a change of the magnetic permeability of the magnetostrictive membrane. In the rotational detection mechanism, the first end portion is adapted to be a free end and a second end portion of the rotational shaft is rotatably supported.

Rotational torque detection mechanism and power steering apparatus

An electric power steering apparatus, which has an electric motor incorporated in a steering system to provide steering power assist directly to the steering system to thereby reduce manual steering effort required by the driver, includes a steering torque differentiating section arranged to output a differential value of a component of the steering torque which is free from a near-dc component and a high frequency component, a motor control signal determining section for subtracting a value corresponding to the steering velocity from a value corresponding the steering torque and adding the value corresponding to the steering torque to a value corresponding to the differential value to thereby determine a motor control signal, and a motor drive section for driving the electric motor on the basis of the motor control signal. With this arrangement, the electric power steering apparatus can improve the response characteristics of the steering power assist system while preventing undue increase in the gain of the control system at low frequencies in the range of 2 to 4 Hz, for example.

Electric power steering apparatus

An electric power steering apparatus includes a steering assist torque control system in which a steering torque signal is input and a motor speed signal is output. The control system includes a main control value setting section having a gain KTT and setting a target assist torque value corresponding to the steering torque, a differential-value correction value setting section having a gain KTD and setting a differential-value correction value corresponding to a differential steering torque value, a motor having an inertial efficiency JM and a counter electromotive force (induced voltage) constant KE, a motor drive section incorporated in a controlled object and having a proportional gain KP, a steering speed correction value setting section having a gain KTR and setting a steering speed correction value corresponding to the motor speed signal. The ratio of the gain KTD to the gain KTT is set to satisfy the condition: KTD/KTT&gt;JM/{.alpha.(KP.multidot.KTR+KE)} where .alpha.=KT/(R+KP), R is the resistance (winding resistance) of the electric motor, and KT is the torque constant of the electric motor. With this arrangement, the phase of a gain of the steering assist torque control system is advanced, thereby improving the response characteristic to a level at least comparable to the manual steering mechanism.

In a control device for an electric actuator of a steering system of a vehicle, the amount of power assist provided by the electric actuator of the steering system is appropriately diminished when the steering wheel is turned more than appropriate under the given road condition so that the effort to turn the steering wheel may not be excessively reduced even on a slippery road surface. Thus, when the vehicle is steered more than appropriate for a given road condition, the steering effort is increased by reducing the power assist of the steering system, whereby the vehicle operator is prevented from excessively steering the vehicle. This increase in the steering effort occurs only when the vehicle operator attempts to increase the steering angle, and does not affect the tendency of the steering wheel to return to its neutral position.

Control device for an electric actuator of a steering system

An electrically operated power steering apparatus in a motor vehicle has a steering system for steering the motor vehicle, a steering torque detector for detecting a manual steering torque applied to the steering system, and an electric motor for generating an assistive torque to be transmitted as a steering assistive force to the steering system. An actual assistive torque detector detects an actual assistive steering torque which is actually transmitted from the electric motor to the steering system. A controller has at least a target assistive torque generator for generating a target value for an assistive torque to be generated by the electric motor depending on the manual steering torque detected by the steering torque detector, and generates a control signal based on the difference between the actual assistive steering torque detected by the actual assistive torque detector and the target value generated by the target assistive torque generator. The electric motor is energized by a motor driver based on the control signal from the controller.

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Wako, Japan

Yoshito Nakamura