Position sensor

Details Position sensor Position sensor

2002-01-16

2004-06-22

Strecker, Gerard R. (Department: 2862)

Electricity: measuring and testing

Magnetic

Displacement

C324S207240, C324S207250

Reexamination Certificate

active

06753680

ABSTRACT:

BACKGROUND OF THE INVENTION
1. Field of the Invention.
The present invention relates to electromagnetic sensor assemblies, and, more particularly, to electromagnetic position sensor assemblies.
2. Description of the Related Art.
Electronic devices are an increasing part of everyday life and they are presently integrated in a large number of products, including products traditionally thought of as mechanical in nature, such as automobiles. To bridge the gap between mechanical movement and electronic control it is necessary to successfully integrate electronic and mechanical components. The gap is normally bridged by using devices such as sensors and actuators.
Position sensors are used to electronically monitor the position or movement of a mechanical component. The position sensor produces data that may be expressed as an electrical signal that varies as the position of the mechanical component changes. Position sensors are an important part of innumerable products, providing the opportunity for intelligent control of a mechanical device.
Various contact type sensors are known. For example, potentiometers are used which detect a change in an electrical signal due to the physical change in position of a wiping contact on a resistive element. Rotational position movement can be detected by coupling a shaft of a potentiometer to the shaft of a rotating mechanical component. Linear movement can be detected using either a liner potentiometer or a rotating potentiometer that is coupled to a linear moving component using pulleys and a string or a belt to translate a linear motion to rotational motion. A problem with this type of sensor is the physical wearing of the rotating part, the wiping contact and the resistive element cause a drift in the electrical signal and lead to ultimate failure of the device.
Magnetic position sensors are generally a non-contact type of sensor and consist of a magnetic field sensing device which is usually stationary and a magnet that is attached to a moving component. As the magnet approaches the sensing device the magnetic field of the magnet is detected and the sensing device generates an electrical signal that is then used for counting, display, recording and/or control purposes. A problem with such sensors is that they depend on movement of the magnet and they are not able to provide information as to the static position of a mechanical component.
Other magnetic position sensors provide an indication of the displacement of the mechanical component by using a magnetic field sensing device which reports the intensity of a magnetic field from a magnet which is positioned on the mechanical component. The magnet is positioned and the magnetic field sensing device is located relative to the magnet in such a fashion as to cause the magnetic field to vary in the magnetic field sensing device as the magnet moves. A magnetic field sensing device may detect a static magnetic field from the magnet and report the field strength as a representation of the position of the mechanical component.
A magnetic positional sensor developed by the inventor, patented as U.S. Pat. No. 5,818,223, entitled “ROTARY POSITION SENSOR WITH CIRCULAR MAGNET”, discloses a Hall effect device disposed within a cylindrically shaped magnet. The magnet having a magnetic field that varies from a north pole to a south pole as detected along a circular face of the magnet. The cylindrical magnet is mounted to a rotatable mechanical component and a Hall effect device is positioned inside the cylindrical magnet with an air gap therearound. The Hall effect device has flux concentrators mounted thereto. The magnetic field produced by the cylindrical magnet is detected by the Hall effect device which in response thereto produces an electrical response representative of the magnet and hence the mechanical component's angular position.
A problem with such sensors is that they require large magnets.
Another problem with rotating sensors is that they require a stationary and a movable portion within a single assembly.
What is needed in the art is a compact modular position sensor which will provide static and moving position information using smaller magnets.
SUMMARY OF THE INVENTION
This invention relates to a position sensor which senses the linear or radial position of a mounted device. The sensor includes at least one elongated ferrous plate and a pair of magnets at spaced locations along the plate. An electronic signal generating device responsive to the flux density of the magnets along the plate is provided between the magnets with the plate being movable relative to the signal generating device.
Accordingly, it is an object of this invention to provide a position sensor which is of economic construction and which may sense the position of a mounted device either in a lateral orientation or a radial orientation.
It is another object of this invention to provide a position sensor which is for sensing the position of a mounted device and which allows a substantial relative movement between the mounted device and the sensor components.
A further objective of this invention is to provide a position sensor which utilized a Hall effect integrated circuit with the ability to sense either linear or radial movement.
Other objects of this invention will become apparent upon reading the following description.
BRIEF DESCRIPTION OF THE DRAWINGS
The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of embodiments of the invention taken in conjunction with the accompanying drawings, wherein:
FIG. 1
is a side view of one embodiment of this invention;
FIG. 2
is a sectionalized end view of the embodiment of
FIG. 1
;
FIG. 3
is illustrative of three views of the embodiment of
FIG. 1
showing the Hall effect device in three different operative positions;
FIG. 4
is a graph showing in the horizontal axis the position of the Hall effect device relative to the ferrous plates and in the vertical axis the magnetic field strength that is sensed by the hall effect integrated in circuit relative to the positions shown in
FIG. 3
;
FIG. 5
is a graph showing in the horizontal axis the linear position of the Hall effect integrated circuit and in the vertical axis the output signal strength of the Hall effect device relative to the position as shown in
FIG. 3
;
FIG. 6
is a side view in sectionalized form of another embodiment of this invention;
FIG. 7
is a sectionalized end view of the embodiment of
FIG. 6
;
FIG. 8
is a side view of a third embodiment of this invention;
FIG. 9
is a sectionalized end view of the embodiment of
FIG. 8
;
FIG. 10
is a graph showing in the horizontal axis the position of the Hall effect device in
FIG. 8
relative to the ferrous plates of that figure and in the vertical axis the output signal strength of the Hall device relative to three positions of the Hall device;
FIG. 11
is a top view of another embodiment of this invention showing parallel curved plates;
FIG. 12
is a side view in form of the embodiment of
FIG. 11
;
FIG. 13
is a partial top view of still another embodiment of this invention showing curved plates;
FIG. 14
is a side view in sectionalized form of the embodiment of
FIG. 13
;
FIG. 15
is a partial top view of another embodiment of this invention showing curved plates and indicating the direction of rotation of the plates relative to the Hall effect device;
FIG. 16
is a side view in sectionalized form of the embodiment of
FIG. 15
;
FIG. 17
is a partial top view of another embodiment similar to the embodiment of
FIG. 15
but showing two Hall effect devices;
FIG. 18
is a side view in sectionalized form of the embodiment of
FIG. 17
;
FIG. 19
is a partial top view of another embodiment of this invention showing opposed circular plates in which the direction of rotation of the plates and magnets relative to the Hall effect device is shown;
FIG. 20
is a side view in sectionalized form of the emb

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