Electricity: conductors and insulators – Conduits – cables or conductors – Buoyant
Reexamination Certificate
2000-10-10
2002-07-30
Reichard, Dean A. (Department: 2831)
Electricity: conductors and insulators
Conduits, cables or conductors
Buoyant
C367S020000, C367S154000
Reexamination Certificate
active
06426464
ABSTRACT:
BACKGROUND OF THE INVENTION
(1) Field of the Invention
This invention relates to a cable sectional assembly which houses a series of concatenated electronic modules, and which allows for the assembly to flex without damaging the connections between the electronic modules and the wires, microwave signal coaxial cables or other forms of electrical hook-up media connecting the modules, and which has strong backbone and integral strength while nevertheless being sufficiently flexible for high flexture applcations.
(2) Description of the Prior Art
Notwithstanding the term “Prior Art” being used in the caption of this subsection, and as a legend in connection with
FIG. 1
, it is to be understood that the term is not intended to mean or imply that the inventors admit that any technology characterized as an unsuccessful attempt, or that the apparatus depicted in
FIG. 1
, constitutes a 35 USC §102 anticipation of the present invention.
Naval submarines are provided with radio reception while submerged through the facility of a buoyant cable antenna (BCA) system which consists of a multisectional cable which trails behind the submarine. A predetermined trailing portion of the multisectional cable is buoyant and floats on the surface, including the trailingmost section which is a cable section housing a single-conductor antenna element. As an improvement of the BCA system, a new capability was conceived of inserting a section of the cable line immediately inboard of the single-conductor antenna element section which houses a series of electronically concatenated electronic circuit modules. These modules provide radio electronics functions which enhance and/or augment the BCA system's radio electromagnetic wave pickup capablility.
Prior to the present invention the sections of the BCA line were of a form of construction having the core structure of the cable surrounded by a layer of polyethylene applied as a molten extrusion. However, because polyethylene requires high heat during the extrusion process, it was dismissed as a molding material for fear that electronics molded therein would be damaged by the extreme heat. Accordingly, a room temperature curing compound, namely polyurethane, was looked to for the molding compound.
U.S. Pat. No. 5,606,329 to Ramotowski et al, entitled “Buoyant Cable Antenna”, discloses a form of construction of a cable sectional assembly in which a radio electronics package is surrounded by a cured polyurethane and microballon composition.
One prior approach employed in an attempt to devise an operationally satisfactory cable sectional assembly for housing concatenated electronic modules employed hard polyurethane encapsulant being locally distributed around the circuit modules, with a softer an overmolding of a mixture of polyurethane and buoyant particulates distributed between the modules and around the hook-up media, as shown in the prior art
FIGS. 1 and 1A
. In this construction the polyurethane and buoyant particulate mixture was molded into direct contact with the items of hook-up media between modules. This approach was abandoned because it was found that assemblies fabricated in this way exhibit a plurality of problems which are basically related to the flexing of the wires, microwave coaxial cables, or other forms of electrical hook-up media potted within the mixture.
More specifically, during testing of a construction of cable sectional assembly fabricated in accordance with this prior approach to devise the assembly, problems arose as the cable was flexed around a 12-inch diameter mandrel which simulated the intended operational environment in which the assembly would be deployed and retrieved by a 12-inch power capstan. The continuity of the electronic modules and their hook-up media became intermittent, eventually forming an open circuit. It was discovered that the flexing of the cable sectional assembly had caused the connections of the hook-up media with the electronic modules to fracture at the soldered joints which formed the electrical coupling connection at the juncture between each end of a hook-up medium and a terminal of the adjacent electronic module. As may be seen in
FIG. 1A
, the hard polyurethane encapsulant and the molding of a mixture of polyurethane and buoyant particulates hold the electrical hook-up media in fixed relationship to the electronic modules as the cable sectional assembly is flexed. The junctures between the ends of the hook-up media and the terminals of the modules become stressed, causing fractures of the soldered connections along the length of the assembly.
While the following patents do include cable designs directed for underwater use as well as cable antennas, none of these patented constructions solve the defects discussed above.
U.S. Pat. No. 1,557,049 to Hammond, Jr. discloses a buoyant electrical antenna. The electrical antenna of Hammond includes an assembly which uses a rigid tubular member extending from an underwater device to the water surface. A single conductor running through the center of the rigid member is used which then extends into a flexible casing having a cylindrical shape with a cavity for encasing the single conductor. Insulating standoffs are used to maintain proper spacing of the single conductor relative to the outside wall of the cylindrical flexible member. The single conductor is insulated and obtains its buoyancy through the use of the flexible cylindrical member being filled with air.
U.S. Pat. No. 4,011,540 to Farr discloses a combined electret hydrophone and transmission line which comprises a plurality of coaxial cable segments coupled by electronic circuit modules, wherein the coaxial cable segments serve as seismic detectors, signal transmission, lines and power supply lines. The coaxial cables of Farr use polytetrafluoroethylene (“PTFE”) as an integral part thereof for the dielectric material between two conductors. Accordingly, the PTFE used is a part of the coaxial cable provided in Farr, but there is no cavity in which a coaxial cable can loosely fit and independently flex so as to avoid high stress occurring at points of Farr's coaxial cables' connections with the electronic circuit modules. Therefore, it is probable that in high flexibility applications, the cable of Farr would not maintain constant transmission capabilities since high stress points would develop and would thereby cut off transmission where the stress points lead to joint fracture. Further, the PTFE layer used in Farr is not firmly bonded at its outer surface to the remaining layer of the coaxial cable thereby causing a weaker assembly to be formed. Still further, Farr's cable assembly is constructed to have a neutral buoyancy, not a positive buoyancy.
U.S. Pat. No. 4,183,010 to Miller discloses a pressure compensating coaxial line hydrophone and method for detecting mechanical vibrations. The coaxial line includes a coaxial electric cable transducer which includes a combination of an electret with a polymer material having piezoelectric properties. The electret and polymer material are separate flexible materials radially stacked within the cable and preferably constitute a single material formed to have both electret and piezoelectric properties. One polymer which is useful as the piezoelectric material is polyvinylidene fluoride. Similar to Farr, Miller uses PTFE as a dielectric layer between two conductors and not as a protective cable conduit internal to a buoyant cable. In addition, the outer surface of the PTFE layer of Miller's invention is not etched so as to securely bond with surrounding materials. Again, Miller suffers from the defect in Farr in that flexing of the cable could lead to the formation of high stress points at the connection of the cables with electronic equipment. As a result, it appears that intermittencies in proper functioning of the coaxial line hydrophone would occur if the line were to be used in an operational environment involving severe flexing.
U.S. Pat. No. 4,336,537 to Strickland discloses a bi-directional underwater communication sys
Portofee Donald C.
Ramotowski Thomas S.
Spellman Charles D.
Lall Prithvi C.
McGowan Michael J.
Nino Adolfo
Oglo Michael F.
Reichard Dean A.
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