Patent Application
20080303515
1. Field of the Invention
The present invention relates to a position sensor, and, more particularly, to a rotatable linear position sensor.
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. This 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 electrical signal due to a physical change in position of a wiping contact on an electrical 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 either using a linear 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 contacting parts. The wiping contact and the resistive element can cause a drift in the electrical signal, which induces errors and may lead to ultimate failure of the device.
Magnetic velocity sensors are generally a non-contact type of sensor and consist of a magnetic field sensing device, which is usually stationary, and a magnet 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, displaying, recording and/or control purposes.
What is needed in the art is a linear position sensor that is substantially unaffected by a rotation of a component.
The present invention provides a linear position sensor that is insensitive to the rotation of portions thereof.
The invention comprises, in one form thereof, a position sensor including at least one magnet producing a magnetic field, at least one magnetic flux sensing device sensing the magnetic field, and a ferrous sleeve. The ferrous sleeve being rotatable about a longitudinal axis of the magnet. The magnetic field detected by the magnetic flux sensing device being substantially unaffected by rotation of the ferrous sleeve relative to the magnet.
An advantage of the present invention is that the magnet can be rotatable about a longitudinal axis yet the sensor can sense the linear longitudinal position of the magnet.
Another advantage of the present invention is that in addition to the rotation of the magnet, the sleeve that somewhat encompasses the magnet can be rotatable relative to the magnet without affecting the linear position detection thereof.
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 an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:
Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates a preferred embodiment of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner.
Referring now to the drawings, and more particularly to
Sleeve 12 is movable in a longitudinal direction, and is movable relative to the magnet 14 and magnetic flux sensor 16 as illustrated in three different views shown in
Now, additionally referring to
Now, additionally referring to
There is also contemplated that multiple magnetic flux sensing devices 16 or 116 may be positioned at other points along the travel of sleeve 12 or magnet 114. The electronic circuitry connected to magnetic flux sensing device 16 or 116 to convey signals therefrom are also contemplated in the embodiment of the present invention.
While this invention has been described with respect to preferred embodiments, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.
