Electric power assisted steering systems
First Claim
1. Electric power assisted steering system comprising:
- a steering shaft operatively connected at a first end to a handwheel and at its other end operatively connected to at least one roadwheel, an electric motor having a rotor, a gearbox operatively connecting said steering shaft to said rotor, said gearbox having a non-integer reduction gear ratio, a first sensor adapted to produce an output dependent on the angular position of said steering shaft;
a second sensor adapted to produce an output dependent on the angular position of said rotor, and processing means adapted to process both output signals to produce an angular position signal indicative of the angular position of said steering shaft over a range of greater than one complete revolution.
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Accused Products
Abstract
An electric power assisted steering system is disclosed which comprises a steering shaft connected at one end to the handwheel and at its other end to at least one roadwheel, while an electric motor is connected to the steering a gearbox having a non-integer reduction gear ratio. Two sensors are also provided with one sensing the angular position of the motor rotor and the other sensing the angular position of the steering shaft. The presence of the non-integer gear ratio produces a beat frequency between the output of the two sensors from which an unambiguous measurement of the angular position of the steering shaft over a range of greater than one complete revolution can be made. The sensors may comprise either absolute position sensors or index-type sensors.
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Citations
15 Claims
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1. Electric power assisted steering system comprising:
- a steering shaft operatively connected at a first end to a handwheel and at its other end operatively connected to at least one roadwheel, an electric motor having a rotor, a gearbox operatively connecting said steering shaft to said rotor, said gearbox having a non-integer reduction gear ratio, a first sensor adapted to produce an output dependent on the angular position of said steering shaft;
a second sensor adapted to produce an output dependent on the angular position of said rotor, and processing means adapted to process both output signals to produce an angular position signal indicative of the angular position of said steering shaft over a range of greater than one complete revolution. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
- a steering shaft operatively connected at a first end to a handwheel and at its other end operatively connected to at least one roadwheel, an electric motor having a rotor, a gearbox operatively connecting said steering shaft to said rotor, said gearbox having a non-integer reduction gear ratio, a first sensor adapted to produce an output dependent on the angular position of said steering shaft;
Specification