Power assisted steering system for a motor vehicle and control means therefor
First Claim
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1. A power assisted steering system for a motor vehicle having at least one steerable road wheel, the system comprising:
- a steering shaft manually rotatable by a driver of the vehicle;
a steering mechanism to convert rotation of the steering shaft into steering movement of the or each steerable road wheel;
an electric motor having a rotor and a wound stator encircling the rotator;
a torque sensor to provide a signal indicative of the torque difference between the torque applied to the steering shaft by a driver of the vehicle rotating the steering shaft and the assistance torque applied by the electric motor to the steering shaft andcontrol means to supply a control signal to the electric motor in response to the signal received from the torque sensor wherein the electric motor is a brushless electric motor having a number of permanent magnets connected to part of the steering shaft for rotation therewith to form the rotor, each of the permanent magnets connected to a part of the steering shaft by being press fitted into a respective recess in the steering shaft.
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Abstract
A power assisted steering system which utilizes a brushless electric motor having a rotor and a wound stator. The rotor is directly connected to the steering shaft 12 rotated by a driver of the vehicle, and is formed by a number of permanent magnets secured in respective recesses on the steering shaft. The controller 17 associated with the steering system is arranged to switch off the motor 15 above a pre-determined vehicle speed.
27 Citations
5 Claims
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1. A power assisted steering system for a motor vehicle having at least one steerable road wheel, the system comprising:
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a steering shaft manually rotatable by a driver of the vehicle; a steering mechanism to convert rotation of the steering shaft into steering movement of the or each steerable road wheel; an electric motor having a rotor and a wound stator encircling the rotator; a torque sensor to provide a signal indicative of the torque difference between the torque applied to the steering shaft by a driver of the vehicle rotating the steering shaft and the assistance torque applied by the electric motor to the steering shaft and control means to supply a control signal to the electric motor in response to the signal received from the torque sensor wherein the electric motor is a brushless electric motor having a number of permanent magnets connected to part of the steering shaft for rotation therewith to form the rotor, each of the permanent magnets connected to a part of the steering shaft by being press fitted into a respective recess in the steering shaft. - View Dependent Claims (2, 3, 4, 5)
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Specification