Honda Motor Co., Ltd.

Hiroki Sagami

Hiroaki Horii

Kyoji Hamamoto

Fumihiro Morishita

Shinji Hironaka

Takuji Wada

Yoshinobu Mukai

Takashi Kuribayashi

Yoshitake Sakai

Yuki Shiga

An electric power steering device provides an appropriate power assist from the motor even when torque sensors have failed and the steering torque is no longer detected. If an error is detected in a torque sensor, the motor is driven based on the rotor rotation angle detected by a resolver and assist characteristics. When the absolute value of the rotor turning angle velocity calculated based on the rotor rotation angle falls to or below a prescribed value, a process is started for reducing the current driving the motor, and if the state in which the absolute value of the rotor turning angle velocity has fallen to or below the prescribed value continues over a prescribed length of time, the process for reducing the current is interrupted and, because an assist current was flowing at said time of interruption, an appropriate power assist can be given during a steering retention period.

Electric power steering device

Disclosed is an idle stop control device capable of relieving reaction force (kickback) of a handle occurring at idle stop controlled by the control of the idle stop control device. Specifically, an EPSECU () detects the rotational speed of an electric motor by detecting the rotational angle (&#x3b8;) of the electric motor using a resolver (), and at the same time, detects the steering torque using a torque sensor (). Subsequently, the EPSECU determines whether or not the rotational speed of the electric motor and the steering torque are inside an idle stop transition area (P) by referring to a table () stored in a memory () in advance. When either or both of the rotational speed of the electric motor and the steering torque are outside the idle stop transition area (P), a signal requesting the prohibition of idle stop transition is output to an idle stop control device () via a cable (). Upon receiving the signal requesting the prohibition of idle stop transition, the idle stop control device () prohibits the control of transition to idle stop even when conditions for idle stop are met.

Idle stop control device

Disclosed is an electric power steering device capable of applying a prescribed steering assist force to a steering assembly, even when a torque sensor is out of order and the electric power steering device is in a state of being unable to sense steering torque by the torque sensor. Using an angle of rotation of a rotating element, which is detected by a resolver that serves as a rotating element angle of rotation sensing unit of a motor, a steering angle and a steering angular velocity are estimated, and a prescribed steering assist force is applied to a steering assembly by the motor, on the basis of an estimated steering angle and/or an estimated steering angular velocity.

An electric power steering apparatus detects, as an abnormal phase, a phase other than a combination of phases whose interphase voltage is of nearly zero volts if a q-axis current is equal to or smaller than a first threshold value though a q-axis voltage is being applied. Alternatively, the electric power steering apparatus calculates a base electric angle at which the q-axis current is equal to or smaller than a third threshold value though the q-axis voltage is being applied, and determines an abnormal phase based on the base electric angle.

Electric power steering apparatus

An electric motor is driven with high output at the time of low-speed running, and a steering at a high resolution is enabled at the time of fast-speed running. An electric power steering device causes the electric motor to generate auxiliary torque in accordance with the largeness of steering wheel torque by the steering operation of a wheel made by a driver and reduces the steering wheel torque to the driver. A control device drives, based on a vehicle-speed signal (Vs) from a speed sensor, the electric motor with high output at the time of low-speed running, and enables steering at a high resolution at the time of fast-speed running without increasing an electric-motor output.

Growing community of inventors

Utsunomiya, Japan

Hiroki Sagami