Hall effect contactless position sensor providing a direct propo

Details Hall effect contactless position sensor providing a direct propo Hall effect contactless position sensor providing a direct propo

1997-12-23

2000-05-09

Strecker, Gerard

Electricity: measuring and testing

Magnetic

Displacement

73DIG3, 32420726, G01B 714, G01B 702, G01D 514

Patent

active

060608803

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

1. Field of the Invention
The invention relates to a contactless position sensor using a Hall effect cell and a specific magnetic circuit making it possible to directly obtain an output signal, whose value varies linearly with the distance separating the sensor from a magnetic target positioned facing the latter.
Such a sensor can be used for any contactless distance measurement, provided that the target is made from a soft ferromagnetic material. Thus, said sensor is independent of the target size and can be used both when the latter is moving and when it is stationary. Therefore the position sensor according to the invention requires no modification of the target, whose position it is desirable to know.
2. Discussion of the Background
Numerous contactless position sensors exist, which are based on different physical principles, whereof in exemplified manner reference is made to optics, ultrasonics, eddy currents, etc.
The choice of a particular sensor is generally made as a function of the nature of the material constituting the target and taking account of the particular conditions under which the measurement has to take place, such as the dimensions of the target, its fixed or mobile nature, the available space, etc.
Numerous existing contactless position sensors are either space-consuming means or require a specific environment making them unsuitable for numerous applications (optical or ultrasonic sensors and the like), or are not very space consuming, but whose output signal must be subject to subsequent electronic processing in order to render it usable (eddy current sensors, etc.).


SUMMARY OF THE INVENTION

The invention specifically relates to a contactless position sensor, whose original design enables it to have reduced overall dimensions and to deliver output signals directly proportional to the distance separating the sensor from the target.
According to the invention, this result is obtained by means of a contactless position sensor using a Hall effect cell and a specific magnetic circuit constituted by a magnet and two pole pieces.
More specifically, the present invention proposes a Hall effect position sensor, characterized in that it comprises a magnet and a Hall effect cell juxtaposed between two pole pieces having, opposite the Hall effect cell relative to the magnet, active surfaces which can be placed at a distance e from a magnetic material target, so that a magnetic flux created by the target is channelled by the pole pieces and distributed on the one hand in the target and on the other, across the Hall effect cell and that the latter then directly delivers an output signal (Va-Vb) proportional to the distance e.
In a preferred embodiment of the invention, the magnet is a permanent magnet delivering a constant magnetic field Ha oriented in a given direction, the active surfaces of the pole pieces being placed in the extension of one another and are oriented parallel to said direction, the Hall effect cell being oriented so as to detect a magnetic induction B oriented parallel to said direction.
In the preferred embodiment of the invention, the pole pieces have two facing, parallel, planar faces, in contact with two opposite, planar parallel faces of the magnet and spaced by the same distance L with respect to the two opposite, planar, parallel faces of the Hall effect cell. The relation:


Sa+Sec/L<<Sent/2e
cross-sections of the magnet, the Hall effect cell and the air gap separating the active surfaces from the target.
Preferably, the active surfaces of the pole pieces have shapes complimentary of those of a surface facing the target. Thus, said active surfaces can be planar surfaces or cylindrical, concave surfaces, depending on whether the surface facing the target is itself planar or cylindrical.
According to particular arrangements and solely as examples, the sensor can have a circular or rectangular section in a plane parallel to the direction of the magnetic field delivered by the permanent magnet.


BRIEF DESCRIPTION OF THE DRAWINGS

The

REFERENCES:
patent: 3440527 (1969-04-01), Steingroever
patent: 3568180 (1971-03-01), Rosch
patent: 4229696 (1980-10-01), Gustafson
patent: 4897914 (1990-02-01), Loubier

Affiliated with

Also associated with

Rating

Hall effect contactless position sensor providing a direct propo does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Hall effect contactless position sensor providing a direct propo, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Hall effect contactless position sensor providing a direct propo will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1068479