Non-oriented direct coupled gear tooth sensor using a Hall cell
First Claim
1. A direct coupled gear tooth sensor to sense the presence or absence of gear teeth or similar ferrous objects as they rotate past a sensor, independent of the angular orientation of said sensor to said gear teeth, comprising:
- a single permanent magnet;
a substantially planar Hall cell integrated circuit package having opposed first and second planar surfaces, said package being positioned adjacent to one polar end of said magnet such that the flux lines from said magnet have essentially no component perpendicular to the plane of said Hall cell in the absence of said teeth;
means to steer and concentrate the flux lines of said magnet perpendicular to the plane of said Hall cell when said flux lines are modulated by the presence of a ferrous gear tooth or similar ferrous object, said means comprising first and second soft iron flux concentrators appended to said one planar end of said magnet, said concentrators being arranged adjacent respective opposed planar surfaces of said package and off center from each other.
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Accused Products
Abstract
A non-oriented direct coupled sensor for gear teeth or similarly shaped discontinuities of a ferrous magnetic or magnetic target uses a single magnet and a direct coupled Hall cell integrated circuit to detect the presence or absence of gear teeth. The sensor incorporates techniques for flux steering and flux reversals independent of the orientation of the sensor to the target to overcome the operate or release point of a Hall switch, latch or other device. The use of spaced apart, offset flux concentrators provides a sensitive device with favorable tolerances in temperature and air gap.
123 Citations
11 Claims
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1. A direct coupled gear tooth sensor to sense the presence or absence of gear teeth or similar ferrous objects as they rotate past a sensor, independent of the angular orientation of said sensor to said gear teeth, comprising:
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a single permanent magnet; a substantially planar Hall cell integrated circuit package having opposed first and second planar surfaces, said package being positioned adjacent to one polar end of said magnet such that the flux lines from said magnet have essentially no component perpendicular to the plane of said Hall cell in the absence of said teeth; means to steer and concentrate the flux lines of said magnet perpendicular to the plane of said Hall cell when said flux lines are modulated by the presence of a ferrous gear tooth or similar ferrous object, said means comprising first and second soft iron flux concentrators appended to said one planar end of said magnet, said concentrators being arranged adjacent respective opposed planar surfaces of said package and off center from each other. - View Dependent Claims (2, 3, 4, 6, 7, 8, 9, 10, 11)
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5. The sensor of claim 5 wherein said Hall cell is located substantially in the center of said package, said first flux concentrator has one end even with the center line of said Hall cell package, and said second flux concentrator likewise has one end even with the center line of said Hall cell package.
Specification