Noncontacting position sensor for an automotive steering system
First Claim
1. In a motor vehicle steering system in which steering is achieved via linear displacement of a rack mechanism with respect to a housing member along a longitudinal axis, apparatus for detecting the position of the rack mechanism as a measure of the steering angle, comprising:
- sensor means including first and second magnetoresistor elements secured to said housing member in proximity the rack mechanism on an axis transverse to said longitudinal axis;
means defining a surface feature on the rack mechanism adjacent said magnetoresistor elements and on an axis diagonal to said longitudinal axis for the rack mechanism and the sensor means in relation to the displacement of said rack mechanism; and
means for developing an indication of rack position in relation to the consequent differential resistances of said magnetoresistor elements.
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Accused Products
Abstract
A noncontacting automotive steering angle sensor involving the application of a two element magnetoresistive sensor to an otherwise conventional rack and pinion steering system. The rack is directly coupled to the steerable wheels, and the sensor is integrally mounted in a spring-loaded rack contacting mechanism (contact shoe) used to maintain a meshing engagement between the pinion and the rack. A variable permeability surface is formed on the surface of the rack along the travel path of the sensor such that axial movement of the rack differentially varies the magnetic flux density detected by each element of the sensor. A detector circuit comprising a bridge or simple voltage divider responsive to the differential resistances of the sensor elements develops an electrical signal indicative of the rack position.
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Citations
6 Claims
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1. In a motor vehicle steering system in which steering is achieved via linear displacement of a rack mechanism with respect to a housing member along a longitudinal axis, apparatus for detecting the position of the rack mechanism as a measure of the steering angle, comprising:
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sensor means including first and second magnetoresistor elements secured to said housing member in proximity the rack mechanism on an axis transverse to said longitudinal axis; means defining a surface feature on the rack mechanism adjacent said magnetoresistor elements and on an axis diagonal to said longitudinal axis for the rack mechanism and the sensor means in relation to the displacement of said rack mechanism; and means for developing an indication of rack position in relation to the consequent differential resistances of said magnetoresistor elements. - View Dependent Claims (2, 3, 4, 5)
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6. In a motor vehicle steering system including a rack member linearly displaceable within a housing member along a longitudinal axis to effect vehicle steering, a pinion gear drivingly engaged with said rack mechanism to control its displacement, and a contact member secured to said housing member opposite said pinion gear and resiliently contacting said rack mechanism for maintaining the engagement between said pinion gear and rack mechanism, apparatus for detecting the position of the rack mechanism as a measure of the steering angle, comprising:
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sensor means including first and second magnetoresistor elements mounted in a central cavity of said contact member, the magnetoresistor elements being disposed in proximity to the rack mechanism on an axis transverse to said longitudinal axis; means including a ferromagnetic bar member secured to said rack mechanism for linear displacement therewith and received within a channel formed in said contact member between said rack mechanism and said magnetoresistor elements, the bar member having a groove formed therein substantially along an axis diagonal to said longitudinal axis to define first and second differential are ferromagnetic surfaces magnetically coupled to said sensor means through said first and second magnetoresistor elements; and means for developing an indication of rack position in relation to the consequent differential resistances of said magnetoresistor elements.
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Specification