Electric power steering device

Abstract

Abstract PURPOSE:To make the change of a steering feel due to the car speed change smaller by a method wherein a torque is generated at a motor in proportion to a steering torque and yet the energizing of the motor is prohibited when the car speed exceeds a set value. CONSTITUTION:When the car speed detected by a car speed sensor SS is lower than a set car speed Vm set by the variable resistor in a comparator B15, a low level L is applied to the input terminal F of a logic control circuit B16. When steering is performed with a torque larger than the predetermined steering torque, the level of the input terminal A of B16 is set by torque sensors 8 and a pulse is applied to the input terminal B of B16 from a pulse-width modulation circuit B6. B16 controls switching transistors Q1-Q4 in response to the pulses in order to drive a servo-motor DM with a current in proportion to the steering torque. When the car speed reaches the set car speed Vm, a high level H is applied to the input terminal F of B16. Consequently, B16 prohibits the energizing of the motor DM, resulting in increasing the steering torque by the amount developed by the motor DM.

Inventors

• 👤 Akio Hashimoto
• 👤 昭夫 橋本

Bibliographic Details