Koyo Seiko Company, Ltd.

Ken Fukuda

Hirofumi Matsuoka

Yasuji Noritou

An electric power steering apparatus comprises broken point characteristics determining means for determining a value of a steering torque signal corresponding to a broken point of a broken line function on the basis of a vehicle speed signal from a vehicle speed sensor, a broken line function circuit for determining the broken line function in accordance with the broken point determining signal determined by the broken point characteristics determining means and outputting an analog signal corresponding to the broken line function, and means for determining a target value of a motor current to drive an electric motor for assisting steering on the basis of the analog signal.

Electric power steering apparatus

A switching element for controlling electric power to be supplied to a motor for generating steering assistance power, and a circuit which outputs a control signal to the switching element according to a driving condition are incorporated in an insulating casing. The insulating casing is attached to a housing of a power steering device. An elastic heat-conducting insulating sheet lies between the switching element and the housing. The switching element is pressed against the housing via the sheet.

Power steering device

An electric power steering apparatus comprising a broken-line function circuit for outputting a predetermined analog broken-line function signal on the basis of a torque detection signal, a gain circuit for giving a predetermined gain to the broken-line function signal, a polarity inverting circuit for inverting the polarity of the broken-line function signal, a first attenuating means for attenuating the torque detection signal at a predetermined rate, a second attenuating means for attenuating an output signal of said polarity inverting circuit at a predetermined rate, an addition circuit for adding a signal from the first attenuating, a signal from the second attenuating means and an output signal of the gain circuit, and outputting the addition value as a target value of a motor current, and a differential amplifying circuit for calculating a difference between the target value and the motor current detected by a detecting circuit for the purpose of feedback control, wherein a steering force assisting motor is driven on the basis of an output signal from the differential amplifying circuit.

A power steering apparatus for use in association with an electric motor, includes a switch circuit driven by a PWM wave signal which switches between one polarity and the other of the voltage developed across a motor-driving current detecting resistance synchronously with the PWM wave signal so as to detect the magnitude and direction of the motor-driving current, thereby controlling a duty cycle of the PWM wave signal in accordance with the detected motor-driving current. Thus, the motor steering touch and feeling is enhanced.

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Kashiwara, Japan

Ken Fukuda