Electricity: magnetically operated switches – magnets – and electr – Magnets and electromagnets – Magnet structure or material
Reexamination Certificate
2000-04-11
2001-10-16
Barrera, Ramon M. (Department: 2832)
Electricity: magnetically operated switches, magnets, and electr
Magnets and electromagnets
Magnet structure or material
C335S302000, C335S306000, C324S326000
Reexamination Certificate
active
06304163
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention pertains to providing locatable identification of non-metallic secreted objects and continuous lines and more particularly to providing and to locating non-metallic objects, such as buried plastic pipe so that they can easily be located and their path traced without disturbing the objects.
2. Description of the Related Art
In general, identification of buried non-metallic objects, such as duct pipe and fiber optic transmission lines, include magnetic lines located helically around non-metallic ducts to identify non-metallic objects buried beneath the surface. Almost all provide for an elongated magnetic device that is magnetized transverse to its length. The following patents represent the state of the art in providing magnetic type of identification for buried objects or transmission lines.
U.S. Pat. No. 5,006,806, titled “Methods and Apparatus Employing Permanent Magnets for Marking, Locating, Tracing and Identifying Hidden Objects Such as Buried Fiber Optic Cables”, issued to John B. Rippingale, et al. relates to providing elongated permanent magnet identifier devices having magnetic fields that may be detected at a distance from the objects. In one embodiment the identifier device comprises an elongated strip magnetized in the direction of its width and formed into a long pitch helix, producing a characteristic “magnetic field signature” that enhances detection and identification of the object, as by a portable gradiometer that is moved over the surface of the earth along a line generally parallel to the length of the object. This embodiment may provide a magnetic field that diminishes as the square of the distance from the identifier device (rather than the usual cube of the distance,) thereby enabling detection at substantial distances. In a second embodiment, distinctive magnetic field signatures are produced by arrays of spaced permanent magnets, the fields of which add and subtract to provide resultant magnetic fields with both peaks and valleys along a line generally parallel to the length of the object.
U.S. Pat. No. 5,051,034, titled “Magnetically Detectable Plastic Pipe,” issued to William G. Goodman, relates to a magnetically detectable plastic pipe, such as polyethylene, polyvinyl, etc., for underground use that includes a hollow tubular plastic pipe having particles of magnetic material embedded in plastic and secured integrally with the wall of the pipe. The magnetic particles are of iron oxide or barium ferrite and of a size, shape, distribution and proportion such that the plastic pipe may be easily detected by magnetic detection apparatus on the surface when the plastic pipe is buried at a selected depth under the ground. The magnetic particles are uniformly distributed throughout the thickness and uniformly distributed around the entire circumference of the plastic pipe, or the magnetic particles may be distributed in discrete portions of the plastic pipe, as for example, a uniform outer layer of the pipe, or in stripes or strips extending along the pipe. The particles may be extruded with the plastic in forming the pipe, whether uniformly dispersed or in discrete regions, or the pipe may be formed of plastic free of the magnetic particles and the magnetic particles provided in a layer separately adhered to the wall of the pipe. The magnetic strips or magnetic portions of the plastic pipe may have selected areas or portions magnetized to encode information readable from the surface of the ground above the buried pipe or in inventorying pipe on the surface.
U.S. Pat. No. 5,321,361, titled “Apparatus and Method for Directing Magnetically Detectable Plastic Pipe and Other Sources of Magnetic Fields From a Distance Using a Vertically Aligned Gradiometer on a Horizontal Support,” issued to William G. Goodman, relates to an apparatus for manipulation by an operator or user for detecting magnetically detectable plastic pipe and other sources of magnetic fields from a distance. This apparatus has a horizontally oriented support member with a handle extending at an acute angle therefrom. A magnetic field gradiometer comprising a hollow non-magnetic tube with two flux gate magnetometers therein is supported at the distal end of the support member a substantial distance ahead of the operator in a substantially vertical position. The support member includes a microprocessor operatively connected through a differential amplifier to the gradiometer for processing signals therefrom. An electronic read out module is supported on the handle spaced from the gradiometer and operable to receive signals from the microprocessor and convert them into an audible or visual display to be sensed by the operator or user. The size and weight distribution of the apparatus and the angles at which the components are assembled assure that when the apparatus is hand held by the handle the gradiometer is balanced in a vertical position at a substantial distance ahead of the operator or user. An alternate embodiment, a magnetic field mapper, is illustrated having a plurality of gradiometers supported in parallel on supporting wheels and having the visual and audio display in the form of a laptop or notebook type computer supported on the handle for the wheeled apparatus. A hand held embodiment of the mapper is also discussed.
SUMMARY OF THE INVENTION
The present invention provides a method and apparatus for polarizing ceramic ferrite with an approximate radial pattern in a non-conductive pipe. The method includes providing two oppositely polarized magnets, each having an arcuate shaped side facing each other to form a generally circular opening. A permanent magnet is suspended within the generally circular opening so that the permanent magnet does not come in contact with the two oppositely polarized magnets. In this manner an annular space is formed between the generally circular opening and the suspended permanent magnet. A non-conductive pipe is passed through the annular space. The apparatus for polarizing ceramic ferrite in a non-conductive pipe includes two oppositely polarized magnets, each having an arcuate shaped side facing each other to form a generally circular opening. A permanent magnet is placed within the generally circular opening so that the permanent magnet does not come in contact with the two oppositely polarized magnets thus forming an annular space therebetween. A centering device associated with the permanent magnet is provided to permit non-conductive pipe to pass through the annular space with the permanent magnet within the non-conductive pipe.
An apparatus for centering a permanent magnet between two oppositely polarized fixed magnets is also disclosed. This apparatus includes a hinge extending from one side of each of the two fixed magnets. An arm is connected to the hinge at one end, this arm having a first biasing member pushing the arm away from the fixed magnet. A spacer device is connected to another end of the arm. The spacer device is in contact with the permanent magnet to position the permanent magnet with respect to the fixed magnets. The spacer device has a second biasing member pushing the spacer from the arm. A second hinge extends from another side of each of the two fixed magnets. A spacer arm is connected to the second hinge. The spacer arm has a first end for positioning the permanent magnet with respect to the fixed magnets. The spacer arm has a third biasing member pushing a second end of the spacer arm from the fixed magnet to which the hinge is attached.
A magnetically identified non-conductive pipe is produced using the method and apparatus for polarizing ceramic ferrite in a non-conductive pipe. The non-metallic pipe contains a predetermined percentage by weight of a ceramic ferrite. The ceramic ferrite is polarized radially in the pipe. The radial polarization has a maximum north pole and a maximum south pole. The poles wind around the exterior of the pipe, periodically concluding a complete revolution.
REFERENCES:
patent: 4764743 (1988-08-01), Leupold et al.
pa
Barrera Ramon M.
Shubert Roland H.
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