Electrical power assisted steering assemblies
First Claim
1. An electric power assisted system comprising a steering assembly, an electric motor which includes a rotor, and a gearbox, said electric motor being operatively connected to said steering assembly through said gearbox to apply an assistance torque to said steering assembly, and further comprising a motor position sensor adapted to produce an output indicative of angular position of said motor rotor, said output undergoing a plurality of transitions as said rotor rotates, a counter adapted to generate a count signal indicative of said transitions in said output of said motor position sensor whereby said count signal is indicative of angular position of said rotor relative to an arbitrary zero position, a steering position sensor having an output which comprises at least one position index signal indicative of a known angular position of a portion of said steering assembly, and a reset means adapted to reset the output of said counter whenever said portion of said steering assembly is at said known angular position by monitoring said index signal.
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Accused Products
Abstract
In an electric power assisted steering system, the output signal from a motor position sensor (9) comprising a number of Hall effect devices (A,B,C) or the like is combined with an index signal from a sensor (108) connected to the steering column shaft (1) or the rack (6) or a yaw sensor or other angular position dependent device to produce an accurate measure of steering angle relative to the straight ahead position. In a preferred arrangement, transitions in the Hall effect sensor output are used to drive a counter (106) which is reset whenever the index signal is produced to ensure it does not drift out over a period of time. Most conveniently, the index signal corresponds to the steering gear straight ahead position.
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Citations
14 Claims
- 1. An electric power assisted system comprising a steering assembly, an electric motor which includes a rotor, and a gearbox, said electric motor being operatively connected to said steering assembly through said gearbox to apply an assistance torque to said steering assembly, and further comprising a motor position sensor adapted to produce an output indicative of angular position of said motor rotor, said output undergoing a plurality of transitions as said rotor rotates, a counter adapted to generate a count signal indicative of said transitions in said output of said motor position sensor whereby said count signal is indicative of angular position of said rotor relative to an arbitrary zero position, a steering position sensor having an output which comprises at least one position index signal indicative of a known angular position of a portion of said steering assembly, and a reset means adapted to reset the output of said counter whenever said portion of said steering assembly is at said known angular position by monitoring said index signal.
Specification