Honda Giken Kogyo Kabushiki Kaisha

Shinzi Hironaka

Yoshinobu Mukai

Yoshiki Noro

Yasuo Shimizu

Takao Kurosawa

Nobuo Sugitani

Mitsunori Kawashima

Osamu Tsurumiya

Shigeru Yamawaki

Yoshito Nakamura

Akio Kobayashi

Susumu Ohta

Shigieru Yamawaki

A current detecting apparatus comprises a determining unit which determines whether the electric potential of a first node or a second node is in a predetermined range. When the condition that the electric potential is not in the predetermined range continues longer than the predetermined period of time, the determining signal indicating the damage occurrence is outputted. Accordingly, the damage of the constituting elements can exactly be determined with the relatively simple configuration in a short time.

Current detecting apparatus and electric motor control apparatus

Control unit in an electric power steering apparatus includes a motor drive inhibition section for inhibiting output of a motor control signal on the basis of at least a steering torque signal supplied from a steering torque sensor. The control unit also includes a zero-value setting section for, when drive inhibition signals are output by the motor drive inhibition section, setting a target motor current signal to a zero value irrespective of a value of the steering torque signal, and an inhibition cancellation section for cancelling the drive inhibition signals when an offset between the target motor current signal and the detected motor current signal becomes zero after the target motor current signal is set to the zero value by the zero-value setting section. With this arrangement, instructions can be communicated bidirectionally from the motor drive inhibition section to a main power steering control where an anomaly has occurred and from the main power steering control to the inhibition cancellation section, so that the inhibition of the motor drive can be canceled promptly.

Electric power steering apparatus

In a motor drive apparatus, a motor drive circuit includes an H bridge circuit composed of four field effect transistors or FETs, and resistors each having electrical resistance sufficiently higher than that of each of the FETs which would be presented when the FET has an ON-state trouble. These resistors are connected in parallel to the respective FETs. To perform a ON-state trouble detecting test on the individual FETs, an OFF signal is fed to all the FETs. If all the EFTS are free of the ON-state trouble, electric potential, representing a result of higher potential of a battery being divided by the resistors, appears at two input terminals of an electric motor connected to the motor drive circuit. If two of the FETs, having their drains connected to a higher-potential electrode of the battery, have the ON-state trouble, the higher potential of the battery appears at the two terminals of the electric motor. If the other two FETs, having their sources connected to a lower-potential or ground electrode of the battery, have the ON-state trouble, the lower or ground potential of the battery appears at the two terminals of the electric motor. These potential appearing at the motor terminals is detected via respective potential detectors.

Motor drive apparatus

An electric power steering apparatus includes a judgment unit which passes a judgment that a condition, in which an offset signal indicative of the offset between a target current signal and a motor current signal, or a drive control signal used for controlling an electric motor is greater than a threshold, has continued for an allowable time. Based on this judgment, a forced drive control unit forcibly drives the electric motor. A fault judgment unit monitors the motor current in all times and judges a current detecting unit to be at fault if the motor current does not vary even though the electric motor is drive forcibly. Thus, even when a failure in the current detecting unit occurs during movement of a motor vehicle, such failure can reliably be detected. Additionally, since the judgment is performed after the electric motor is driven forcibly, misjudgment does not occur even when the judgement at the judgment unit results from continuous application of abrupt manual steering operation.

An electric power steering device for directly applying the power of an electric motor as an auxiliary steering power to a steering system to lower a steering force required of the driver, wherein a current detecting element in a motor current detecting unit is connected in series with the motor, and a drive control unit is operable to always drive, by a PWM signal, that side of switching elements of a bridge circuit to which the motor is connected. With this construction, a high-frequency pulse noise generated upon the PWM driving of the the switching element is absorbed by an inductance in the motor and hence a high-frequency pulse noise detected by the current detecting element can be controlled at an extremely small level. Thus, the electric power steering device can prevent generation of abnormal noises from the motor and oscillation or hunting of the steering system and provide stable steering characteristics.

Electric power steering device

In a controller of an electric power steering apparatus for use with an automotive vehicle, a regenerating condition determining section determines whether or not a motor of the vehicle is in a regenerating condition, and a regeneration control signal generating section generates a regeneration control signal to control the regenerating condition of the motor. A switching section selects between the motor control signal and the regeneration control signal in accordance with a result of determination by the regenerating condition determining section. With this arrangement, a motor current including a regenerative current that is caused to flow in the motor in response to a vehicle driver effecting during-stoppage steering maneuvering and then releasing a steering wheel can be controlled independently of a feedback loop of the controller. The regeneration control signal generating section generates a pulse-width-modulated signal of duty cycle corresponding to the offset between a target current and a motor current flowing in the motor. The regenerating condition determining section determines that the motor is in the regenerating condition if the signs of the target current and motor current control signals do not comport with each other and the direction of the steering torque signal and the rotational direction of the motor are opposite to each other.

An electric power steering apparatus, which provides a steering assist of an electric motor directly to a vehicle steering system to reduce necessary steering power to be applied by a vehicle driver, is provided with a control unit which includes a proportion-coefficient and integration-coefficient setting section for, on the basis of a velocity of the vehicle detected by a velocity sensor, setting sensitivity of a proportioning element and integration gain of an integrating element in such a manner that they take greater values during high-velocity running of the vehicle than during low-velocity running of vehicle. This prevents occurrence of unwanted noises and vibrations during low-velocity running of the vehicle and also enhances steering response during high-velocity running of the vehicle, thus always providing an optimum steering feeling in changing running conditions of the vehicle. The control unit may further include a compensation section provided between an offset calculation section and a proportional and integral control section for, on the basis of the velocity detected by the velocity sensor, modifying the offset signal in such a manner that the offset signal takes a greater value during high-velocity running of the vehicle than during low-velocity running of vehicle.

This invention is an electric power steering apparatus for applying the power of an electric motor to a steering system to reduce the steering torque, comprising a steering torque detection means, steering rotating speed detection means, a differential operation means, an electric motor control signal determination means, and an electric motor drive means. The apparatus detects the steering torque and steering rotating speed of the steering system to generate as an electric motor control signal a control quantity obtained by damping the value corresponding to the steering rotating speed from the value corresponding to the steering torque and then adding to the result a steering torque differential value in order to drive the electric motor based on this electric motor control signal, thereby enabling a steering assist torque corresponding to a change in the steering torque to be obtained even when a steering operation with a sudden increase in the steering torque is performed and thus enabling a responsive steering assist torque to be generated to improve the steering feeling.

An electrically operated power steering apparatus basically has a steering torque sensor, a steering rotational speed sensor, and preferably a vehicle sensor. A controller outputs a motor control signal based on a steering torque, a steering rotational speed, and a vehicle speed which are detected by the steering torque sensor, the steering rotational speed sensor, and the vehicle sensor, respectively. The motor control signal is applied to control a motor driver to output a motor drive signal which energizes an electric motor to produce an assistive steering force or a braking force. The electrically operated power steering apparatus is effective to improve steering and returning characteristics of a steering system, and give the steering system a stable steering capability.

Electrically operated power steering apparatus for assisting manual

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

Shinzi Hironaka