Electricity: measuring and testing – Magnetic – Displacement
Reexamination Certificate
1998-12-01
2001-12-04
Metjahic, Safet (Department: 2862)
Electricity: measuring and testing
Magnetic
Displacement
C324S207200, C324S207250
Reexamination Certificate
active
06326780
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to magnetic position sensors and more particularly to magnetic field concentrators employed in a rotary magnetic sensor.
BACKGROUND OF THE INVENTION
For mechanisms having one portion that rotates relative to another, it is often necessary to know the precise relative rotational position between the two portions. There are many types of sensor arrangements that can accomplish such a task; however, many have drawbacks in that they are too large for a particular application, too expensive to design and fabricate, or require extensive calibration once assembled in the mechanism.
These types of sensors can be used, for example as throttle position sensors, fuel accumulators, transmission position sensors, steering angle sensors, and gear tooth sensors. Many other types of applications of course can also benefit from having rotational position sensing.
Also, of course, it is desirable that the sensor be as inexpensive and easy to fabricate and assemble as possible in order to minimize the cost of the sensor assembly.
Consequently, it is desirable to have a rotational position sensor that does not need calibration, or may need only minimal calibration, is small in size, cost effective, and still reliable.
SUMMARY OF THE INVENTION
In its embodiments, the present invention contemplates a magnetic rotary position sensor. The sensor includes means for producing a generally uniform magnetic field over a sensor region, and a mounting base having a center of relative rotation between the base and the magnetic field. A plurality of generally triangular shaped concentrators are generally uniformly spaced about the center of relative rotation within the predetermined area, with each of the concentrators spaced from adjacent concentrators to form gaps, and with the concentrators made of a magnetizable material. Also, a plurality of magnetic field sensors are mounted to the base and extend radially outward from the center of relative rotation, with each of the magnetic field sensors located in a different one of the gaps. The sensor also includes means for communicating signals through each of the magnetic field sensors.
Accordingly, an object of the present invention is to direct a generally uniform magnetic field across a rotary position sensor assembly such that the magnetic field strength appearing across each individual sensing element of the array is related to the direction of the magnetic field relative to that particular element.
An advantage of the present invention is that the magnetic flux is distributed by the concentrators in a controlled manner over multiple magnetic field sensing elements.
Another advantage of the present invention is that this sensor array can be used with various types and sizes of magnetic field sensing elements. While this invention will operate on large scale assemblies, it will also operate effectively on very small scale assemblies, including micro-scale sensors with the structure built up on a ceramic chip or on a silicon chip which may or may not also contain additional electronic components.
A further advantage of the present invention is that magnetic field direction and hence rotary sensor position can be determined by comparing the responses of the individual sensing elements in the array to each other, without the need for precise temperature and magnetic field calibration in the final assembly.
An additional advantage of the present invention is that the arrangement of the sensor array can be configured so as to make assembly and alignment of the array onto a chip easier.
Another advantage of the present invention is that different configurations of magnets, for producing a magnetic field on the sensor array, can be employed to allow for flexibility of design for the sensor assembly.
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Brinks Hofer Gilson & Lione
Jolly Anthony
Metjahic Safet
Oberholtzer Steven L.
Visteon Global Technologies Inc.
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