Electric power steering device
First Claim
1. A motor driven power steering system for a vehicle comprising:
- an electric motor;
torque detecting means for detecting the steering torque applied to a steering shaft by a driver and producing a torque signal;
electronic control means operatively connected to said motor and said torque detecting means for generating pulses for controlling said motor;
wherein said electronic control means comprises;
polarity detecting means for detecting the direction in which the steering torque is applied to said steering shaft and producing a direction signal;
absolute value circuit means for detecting the magnitude of the steering torque and producing a magnitude signal;
function generating means for de-energizing said motor when said magnitude signal is less than a predetermined level;
pulse duration modulation means for controlling the energization of said motor by changing the pulse duration in response to said direction and magnitude signals; and
closed loop control means for feeding a signal corresponding to the output of said motor back to the input side of said pulse duration modulation means.
1 Assignment
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Accused Products
Abstract
An electric power steering device for vehicles comprises an electric motor connected to a steering shaft and serving as a servomotor for producing assisting steering power. Torque sensors are adapted to sense steering torque on the steering shaft. A vehicle speed detecting means is adapted to detect the actual vehicle speed. A controller is adapted to control the state of energization of the electric motor such that the output torque of the motor is changed in accordance with the change in the steering torque on the steering shaft and that the energization of the motor is stopped when the actual vehicle speed is increased beyond a predetermined threshold speed which is adjustable by a vehicle speed setting means such as a variable resistor.
58 Citations
8 Claims
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1. A motor driven power steering system for a vehicle comprising:
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an electric motor; torque detecting means for detecting the steering torque applied to a steering shaft by a driver and producing a torque signal; electronic control means operatively connected to said motor and said torque detecting means for generating pulses for controlling said motor;
wherein said electronic control means comprises;polarity detecting means for detecting the direction in which the steering torque is applied to said steering shaft and producing a direction signal; absolute value circuit means for detecting the magnitude of the steering torque and producing a magnitude signal; function generating means for de-energizing said motor when said magnitude signal is less than a predetermined level; pulse duration modulation means for controlling the energization of said motor by changing the pulse duration in response to said direction and magnitude signals; and closed loop control means for feeding a signal corresponding to the output of said motor back to the input side of said pulse duration modulation means. - View Dependent Claims (2, 3, 4, 5)
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6. A motor driven power steering system for a vehicle comprising:
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an electric motor; torque detecting means for detecting the steering torque applied to a steering shaft by a driver and producing a torque signal; electronic control means operatively connected to said motor and said torque detecting means for generating pulses for controlling said motor;
wherein said electronic control means comprises;polarity detecting means for detecting the direction of torque detected by said torque detecting means and producing a polarity signal; absolute value circuit means for detecting the magnitude of torque detected by said torque detecting means and producing an absolute signal; torque signal processing means for producing a steering torque signal when said absolute signal exceeds a predetermined level; pulse duration modulation means producing a pulse duration signal in response to said steering torque signal; logic control circuit means for producing a plurality of predetermined output signals in response to said polarity signal and said pulse duration signal; and motor drive circuit means for supplying load current to said electric motor in response to said output signals of said logic control circuit means. - View Dependent Claims (7, 8)
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Specification