Mitsubishi Denki Kabushiki Kaisha

Koji Terauchi

Mitsuharu Morishita

Shinichi Kohge

Tadayuki Hara

A motor-driven power steering system for a vehicle preventing transmission of operating noises of the motor to the interior of the passenger compartment of the vehicle and for suppressing the generation of radio wave noises: a speed sensor for detecting the travelling speed of the vehicle; a torque sensor mounted on a steering shaft for detecting turning force imparted to the steering wheel by an operator, a first pinion operatively connected with the steering shaft and adapted to be driven by the steering wheel through the intermediary of the steering shaft, a rack operatively connected through tie rods with a pair of steerable road wheels and having a first rack tooth portion and a second rack tooth portion formed thereon, a second pinion being in meshing engagement with the second rack tooth portion on the rack, a motor operatively connected with the second pinion for power assisting the steering motion of the rack induced by the operator a first electromagnetic clutch interposed between the motor and the second pinion for transmitting power therebetween substantially in proportion to the intensity of current supplied thereto, a second clutch interposed between the motor and the second pinion for selectively establishing or disconnecting the operative connection between the motor and the second pinion, and a control unit adapted to receive output signals from the speed sensor and the torque sensor for controlling the operations of the motor, the first clutch and the second clutch.

Motor-driven power steering system for a vehicle

A motor-driven power steering system for a vehicle wherein vehicle speed and operator-induced steering torque are detected for the control of power-assisting steering operation; a vehicle-speed sensor for detecting the vehicle speed to generate an output signal representative of the detected vehicle speed; a motor connected to be energized by a battery to transmit a force to the steerable road wheels for power assisting steering motion caused by the operator through the steering wheel; a first electromagnetic sliding clutch for controlling the power-assisting force transmitted from the motor to the steerable road wheels; a second electromagnetic switching clutch connected to be switched off for interrupting the transmission of the power-assisting force from the motor toward the steerable road wheels when the vehicle speed increases above a prescribed level, and switched on for transmission of the power-steering force therebetween when the vehicle speed decreases below the prescribed level; and a control unit connected to receive output signals from the torque sensor and the vehicle-speed sensor for controlling respective running and switching operations of the motor and the first sliding clutch in such a manner that the power-assisting force transmitted from the motor to the steerable road wheels through the first sliding clutch is gradually decreased before the second switching clutch is switched off, and gradually increased after the second switching clutch is switched on.

Growing community of inventors

Akashi, Japan

Koji Terauchi