Electricity: measuring and testing – Fault detecting in electric circuits and of electric components – Of individual circuit component or element
Reexamination Certificate
1999-06-15
2001-07-24
Brown, Glenn W. (Department: 2858)
Electricity: measuring and testing
Fault detecting in electric circuits and of electric components
Of individual circuit component or element
C324S525000, C324S557000, C324S720000, C324S096000, C361S103000, C361S106000
Reexamination Certificate
active
06265880
ABSTRACT:
STATEMENT OF GOVERNMENT INTEREST
The invention described herein may be manufactured and used by or for the Government for governmental purposes without the payment of any royalty thereon.
BACKGROUND OF THE INVENTION
The present invention relates to reducing the failure of a system that carries electrical, optical, or electromagnetic (as in waveguide) signals or that conveys fluids. In particular, it relates to failures of such a system that result from chafing of the conduits within it. Such a system may carry electrical power; fuel, refrigerant, other fluid; or optical and/or electromagnetic signals. Or the system may be hydraulic or pneumatic. Degradation or failure of such a system could also expose the systems around the conduit to adverse effects, as when a spark ignites the contents of a fuel container.
The outer surfaces of electrical, optical, and electromagnetic cables and cable bundles are frequently subject to wear caused by rubbing against external structures. If allowed to proceed, this wear can cause grounding, shorting, or breaking of the cable's internal structures (conductors or optical fibers). Hydraulic, pneumatic, and fuel or other fluid lines, pipes, and hoses are also susceptible to failure from chafing.
Each of these structures susceptible to chafing can be called a “conduit”. This application uses the term conduit for any structure that can fail from chafing, such as a cable, cable bundle, hydraulic hose or pipe, pneumatic hose or pipe, or fuel/fluid hose or pipe.
A conduit often fails before a system's operator knows that the conduit has a chafing problem. Currently nothing is in wide use to detect when a conduit experiences chafing and thus becomes subject to failure. The disclosure of U. S. Pat. No. 4,988,949 is limited to detecting chafing on electrical cables against an electrically grounded structure under constant monitoring. It teaches nothing about either periodic testing or detecting chafing on any conduits other than electrical cables, nor does it detect chafing against a non-electrically grounded structure.
Thus there exists a need for a simpler apparatus and method of detecting chafing on any conduit that is likely to chafe against a non-electrically grounded structure or that requires only periodic monitoring.
SUMMARY OF THE INVENTION
Therefore, one object of the present invention is to provide a mechanism to detect chafing.
Another object of the present invention is to provide a mechanism to detect chafing prior to any damage to the internal structure of a conduit or to systems in the vicinity of the conduit.
Briefly stated, the present invention provides apparatus and method to detect chafing in a conduit, thereby reducing the failure of any system which would be damaged or whose function would be impaired or degraded by abrasion of the conduit. Such a system may carry electrical power, fuel, other fluid, optical or electromechanical signals, or it may be hydraulic or pneumatic. Wear caused by rubbing against external structures is detected by wrapping the conduit with a sensing element (conductive wire or fiber optic cable, or a tube to hold fluid under pressure; such a tube may be wound around the conduit, or it may enclose it.) The sensing element is positioned so that chafing on the conduit breaks or punctures the sensing element well before the conduit fails. Measuring the end to end integrity of the sensing element or performing other tests on it determines whether it has failed, thereby indicating that the conduit's integrity will be compromised unless remedial measures are taken.
According to an embodiment of the invention, a method for detecting chafing of a conduit comprises the steps of: placing adjacent the conduit an effective length of a medium, the medium being capable of conducting a signal, the medium being located so that a chafing object cannot substantially abrade the conduit without causing substantial damage to the medium; determining if there is end-to-end integrity of the medium, whereby lack of the integrity implies chafing; and if at least one of the conduit and the chafing object has an outer surface comprising electrically conductive material and the medium is electrically conductive, a further step, prior to the step of determining, of electrically isolating the medium from any other conductor.
According to a feature of the invention, a method for detecting chafing of a conduit comprises the steps of: placing adjacent to the conduit an effective length of electrically conductive wire, the wire being held substantially against the conduit so that a chafing object cannot substantially abrade the conduit without causing substantial damage to the wire; determining if there is end-to-end integrity of the wire, whereby lack of the integrity implies chafing; and if at least one of the conduit and the chafing object has an outer surface comprising electrically conductive material, a further step, prior to the step of determining, of electrically isolating the wire from any other conductor.
According to another feature of the invention, apparatus to detect chafing in a conduit, comprises: a sensing element placed adjacent to the conduit so that a chafing object cannot substantially abrade the conduit without causing substantial damage to the sensing element; and means for determining end-to-end integrity of the sensing element.
These and many other objects and advantages of the present invention will be readily apparent to one skilled in the pertinent art from the following detailed description of a preferred embodiment of the invention and the related drawings, in which like reference numerals designate the same elements.
REFERENCES:
patent: 4301399 (1981-11-01), Miller et al.
patent: 4386231 (1983-05-01), Vokey
patent: 4891597 (1990-01-01), Asars
patent: 4918977 (1990-04-01), Takahashi et al.
patent: 4950957 (1990-08-01), Asars et al.
patent: 4988949 (1991-01-01), Boenning et al.
patent: 5218307 (1993-06-01), Hiller
patent: 5323117 (1994-06-01), Endoh et al.
patent: 5469066 (1995-11-01), Ito et al.
patent: 5541803 (1996-07-01), Pope, Jr. et al.
patent: 5841317 (1998-11-01), Watkins, Jr. et al.
patent: 5862030 (1999-01-01), Watkins, Jr. et al.
patent: 2062446A (1980-10-01), None
Tensolite; Tensolite announces availabilty of abrasion-sensing versions of patented Shortwatch Predictive Wire-Failure technology in Tufflite 2000 general purpose aircraft wire. News release, Aug. 9, 1999, 3 pages, St Augustine FL.
Born Frank H.
Harris Lamar R.
Stratton Roy F.
Brown Glenn W.
Burstyn Harold L.
Hamdan Wasseem H.
Mancini Joseph A.
The United States of America as represented by the Secretary of
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