Composite cable assembly with neutral buoyancy
09885848 ยท 2018-02-06
Assignee
Inventors
Cpc classification
F16L1/14
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
Y10T428/2933
GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
F16L1/24
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
International classification
G02B6/50
PHYSICS
F16L1/24
MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
G02B6/44
PHYSICS
Abstract
An Above Bottom Fiber (ABF) cable includes an elongated fiber cable having microspheres adhered to the ABF by an adhesive lightly coated to the outer surface of the ABF. The elongated fiber cable is negatively buoyant while the microspheres and adhesives are positively buoyant, resulting in the ABF cable being controllably buoyant in a fluid environment. Anchor lines with optional anchor weights are attached to the fiber cable periodically to prevent the fiber cable from drifting. The microspheres detach slowly from the fiber cable resulting in the ABF cable sinking. All components of the ABF cable are biodegradable.
Claims
1. An elongated cable assembly adapted for use in a water environment having an upper boundary and a lower boundary, comprising: an elongated cable having a naturally negative buoyance in a water environment, the elongated cable having an outer surface; micro particles having a positive buoyancy attached to the outer surface of the elongated cable; the quantity of the micro particles per unit length of the elongated cable being chosen such that the assembly is neutrally or positively buoyant at a suspension depth in the water environment; and wherein a micro particle is defined as a particle having a maximum dimension of about 250 microns.
2. An elongated cable assembly in accordance with claim 1, wherein the micro particles are microspheres.
3. An elongated cable assembly in accordance with claim 2, wherein the microspheres comprises a ceramic powder.
4. An elongated cable assembly in accordance with claim 1, wherein the micro particles are coated on the outer surface of the elongated cable by an adhesive, the micro particles being in direct contact with the adhesive.
5. An elongated cable assembly in accordance with claim 4, wherein the adhesive has a positive buoyancy.
6. An elongated cable assembly in accordance with claim 4, wherein the adhesive is organic.
7. An elongated cable assembly in accordance with claim 4, wherein the adhesive is petroleum jelly.
8. An elongated cable assembly in accordance with claim 4, wherein the suspension depth is controlled by controlling the size of the micro particles, type of the adhesive, and type of the elongated cable.
9. An elongated cable assembly in accordance with claim 1, further comprising anchor lines periodically attached along the elongated cable to keep the elongated cable anchored from drifting off in the water environment.
10. An elongated cable assembly in accordance with claim 9, further comprising one or more anchor weights attached to an end of at least some of the anchor lines.
11. An elongated cable assembly in accordance with claim 10, wherein the anchor weights are degradable.
12. An elongated cable assembly in accordance with claim 9, wherein the anchor lines are degradable.
13. An elongated cable assembly in accordance with claim 1, wherein the micro particles detach from the surface of the elongated cable after a period of time resulting in the cable assembly sinking to the lower boundary of the water environment at a sink rate.
14. An elongated cable assembly in accordance with claim 13, wherein the sink rate is controlled by controlling the size of the micro particles and type of the attachment.
15. An elongated cable assembly in accordance with claim 1, wherein the elongated cable is a raw optical fiber.
16. An elongated cable assembly in accordance with claim 1, further comprising an adhesive attached to and in contact with the outer surface of the elongated cable, wherein the micro particles are attached to the outer surface of the elongated cable by being in direct contact with the adhesive.
17. An elongated cable assembly in accordance with claim 16, wherein the micro particles are microspheres.
18. An elongated cable assembly in accordance with claim 16, wherein the adhesive is petroleum jelly.
19. A method of suspending an elongated cable assembly in a water environment, comprising the steps of: providing an elongated cable having a negative buoyancy; attaching a quantity of positively buoyant micro particles per unit length to the elongated cable such that the elongated cable assembly has a neutral or positive composite buoyancy; wherein a micro particle is defined as a particle having a maximum dimension of about 250 microns.
20. A method of claim 19, wherein the attaching step comprises attaching with an adhesive having a positive buoyancy.
21. A method of claim 20, further comprising the step of the micro particles detaching from the surface of the elongated cable resulting in the cable assembly sinking to the lower boundary of the water environment at a sink rate.
22. A method of claim 21, wherein the sink rate is controlled by controlling the size of the micro particles, type of the adhesive, and type of the elongated cable.
23. A method of claim 20, wherein the elongated cable and the adhesive are degradable.
24. A method of claim 19, further comprising the steps of providing anchor lines and attaching the anchor lines to the elongated cable.
25. A method of claim 24, wherein the anchor lines have a negative buoyancy such that the elongated cable assembly has a controllably composite buoyancy.
Description
BRIEF DESCRIPTION OF THE DRAWINGS
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DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(16) The present invention provides a composite assembly adapted for use in a fluid environment, where an elongated element, such as an optical fiber, having a first buoyancy in a fluid environment and a supplemental filament having second buoyancy different from the first buoyance are connected to one another along their lengths so as to form a composite assembly with a composite buoyancy that is functionally neutral in the fluid environment, allowing the composite assembly to be suspended between an upper and lower boundary of the fluid environment. Such a composite assembly may include an elongated element that is a communication or signal carrying element, such as a raw optical fiber or a jacketed cable having at least one optical fiber surrounded by a jacket. This elongated element, on its own, may have a negative buoyancy in the fluid environment. A supplemental filament, such as a thread, may, on its own, have a positive buoyancy on the fluid environment. The elongated element and the supplemental filament are connected to one another along their lengths, such as by at least partially coiling the supplemental filament around the outer surface of the elongated element. By selecting a quantity of the supplemental filament per unit length of the elongated element, a composite assembly may be formed that is generally neutrally buoyant in the fluid environment.
(17) As will be clear to those of skill in the art, the buoyancy of an element depends on the fluid environment. For example, salt water in the ocean is significantly denser than fresh water. The buoyancy of an element will depend both on its density as compared to the fluid environment and the amount of air that may be entrapped by an element. An element or assembly may be referred to herein as generally neutrally buoyant or functionally neutrally buoyant when that element or assembly may be suspended in the fluid environment between an upper and lower boundary of the fluid environment and the element or assembly will remain between the upper and lower boundaries for more than a trivial period of time. An assembly may be considered to be suspended between the upper and lower boundaries even where a disconnected portion of a supplemental filament extends to the upper or lower boundary. As known to those of skill in the art, the density of water, such as sea water, varies depending on location, depth, and other factors, and may change over time at a given location.
(18) Referring now to
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(21) Referring now to
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(23) According to a further aspect of the present invention, the composite assembly may include more than one supplemental filament. For example, a first supplemental filament may have a positive buoyance while a second supplemental filament has negative buoyancy. Alternatively, both supplemental filaments may have a positive buoyancy or both may have a negative buoyancy. As one example, an optical fiber, having a negative buoyancy in a fluid environment, may have a first supplemental filament connected thereto with the first supplemental filament having a positive buoyancy. The quantity of filament per unit length of optical fiber may be chosen such so that the combination has a buoyancy close to neutral buoyancy in the fluid environment. A second supplemental filament may be connected to the elongated element so as to fine tune the overall buoyancy. For example, if the combination of the elongated element and first supplemental filament is slightly negative, the second filament may add enough buoyancy so as to provide an overall neutral buoyancy. Alternatively, if the elongated element and first supplemental filament have a combined slightly positive buoyancy, the second filament may have a negative buoyancy such that the overall assembly has a neutral buoyancy.
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(28) A composite assembly in accordance with the present invention may take a variety of forms. In some embodiments, the elongated element is a communication or signal carrying element such as an optical fiber cable. However, the present invention also contemplates other types of elongated elements wherein functionally neutral buoyancy is desirable. Examples include other types of elongated communication carrying elements such as wires and cables.
(29) In embodiments of the present invention wherein the elongated element is an optical fiber cable, this optical fiber cable may be either a raw fiber or a jacketed cable having at least one optical fiber surrounded by the jacket. The use of raw fiber is advantageous for some embodiments in that this fiber is less expensive and bulky than jacketed or other types of cables. As known to those with skill in the art, optical fiber typically consists of a core and a cladding with the interface between the core and cladding providing a reflective barrier for containing the optical signal. In some types of optical fiber, the core and cladding are both formed of glass. A coating or jacket may be provided over the cladding to provide some protection. As used herein, a raw optical fiber may mean an optical core, an optical core with cladding, or an optical core, cladding and jacket wherein the jacket is applied directly to the cladding.
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(31) In the description above, a jacketed cable was discussed, as one example of an elongated element for use with the present invention. As used herein, such a jacketed cable means a cable with at least one raw optical fiber, such as in
(32) A supplemental filament used with the present invention may have a positive or negative buoyancy, depending on the buoyancy of the elongated element being supported in a fluid environment and whether the supplemental filament is a first or second supplemental filament. In one example, the supplemental filament is a positively buoyant thread. One example is a polypropylene thread formed of a plurality of tightly wound finer fibers. Such a thread is shown at 100 in
(33) As discussed above, the present invention allows an elongated element to be suspended between an upper and lower boundary of a fluid environment. It should be understood that an elongated element, as this term is used herein, means an element that is very long, such as extending for multiple miles between a ship and a communication site. Such an elongated element may have a width, thickness or diameter that is very small relative to its overall length. Preferably the elongated element has a consistent diameter and construction along its length. An elongated filament for use with the present invention also has a width, thickness or diameter that is very small relative to its overall length. While the elongated element and filament are both illustrated as having a circular cross-section, other cross-sectional shapes may also be used.
(34) Referring again to
(35) The present invention further provides a disposable composite cable assembly adapted for use as an Above Bottom Fiber (ABF) in a fluid environment, such as an undersea communication transport. The disposable composite cable assembly includes an elongated element, such as a raw glass fiber which is negatively buoyant, covered with low-density materials with positive buoyancy. The low-density materials may be micro elements such as microspheres or non-micro materials such as Styrofoam balls.
(36) The low-density materials 122 may be mixed into a grease/gel-like substance 120, such as petroleum jelly, to cover the fiber 110. Alternatively, the fiber 110 may be lightly coated with weak adhesives 120 such as petroleum jelly and then covered with the low-density materials 122 such as flour-like microspheres, as shown in
(37) The low-density materials are positively buoyant. The floating low-density materials cause the coated fiber to float. The coating of the microspheres and the weak adhesives is inert to the fiber, and therefore does not change the surface chemistry of the fiber. Additionally, for certain embodiments, all of the components of the composite cable assembly are individually approved as environmentally-acceptable, including the low-density materials, the weak adhesives, and the fibers, thereby simplifying and lowering the cost of the process to change buoyancy.
(38) The elongated element may be raw fibers or cables. Cables refer to coated or jacketed fibers. The present invention may be utilized with a fiber of any diameter, ranging from 10 microns to several centimeters. A single mode raw fiber is about 250 microns in diameter. The smallest fiber may be about 10-20 microns in diameter. A plastic fiber may be about 600 microns in diameter. The size of the microspheres is comparable to the fiber or cable which the microspheres are attached to. The microspheres range mostly from 10 to 100 microns, with a maximum at 250 microns, preferably 20-60 microns in diameter. The sizes of the microspheres are larger for larger fibers or cables.
(39) In one embodiment, the fiber diameter is about 250 microns, while the microsphere diameter is about 150 microns. The microspheres may be 3M ceramic microspheres or Hy-Tech ThermaCels ceramic paint additives or microspheres which reside in toothpaste as a cleaning agent, as well as other microspheres.
(40) As shown in
(41) The ABF design of the present invention results in all components except for the low-density materials such as the microspheres sinking to the bottom after use. As wave motion and biologics interact with the fiber, the microspheres will detach and float to the surface. When some percentage of the microspheres release, the entire system will become negatively buoyant and all elements will sink to the bottom. Raw fiber optic near the bottom as well as fine biodegradable cotton is broken apart by biologics and currents that move the fiber over coral and sharp rocks. Since the raw fiber is nearly 100% pure silicon, it essentially breaks down into sand. Slowly dissolving/corroding anchor weights hold the fiber in place during the period before they completely dissolve. Adhesive selection can be organic and can dissolve.
(42) The suspension depth and the sink rate of the ABF before the components start to sink to the bottom and dissolve can be controlled by using different types of the adhesives or different size of the microspheres. The weight of the fiber, anchor lines and the optional anchor weights are factors too. For example, for a fiber with a diameter of less than 250 microns, there are less than 4 in.sup.3 and less than 4 ounces of fiber per mile, less than 0.5 in.sup.3 and less than 0.2 ounces of petroleum jelly is needed to attach less than 0.5 in.sup.3 and less than 0.2 ounces of ceramic microspheres to the fiber which is necessary to keep the assembly float. Much less cotton thread than the fiber is needed. For example, for a mile of fiber, less than 0.5 in.sup.3 and less than 0.3 ounces of cotton 1 lb test thread as well as optional corroding weights of less than 0.2 in.sup.3 and less than 0.3 ounces may be used. Only the fiber is continuous. The ceramic microspheres as well as adhesives may be coated to the fiber surface continuously or periodically.
(43) Other than being disposable, certain embodiments of the above bottom fiber of the present invention provides additional benefits such as its low cost, reliability, low SWaP, high gbps throughput and rapid replaceability.
(44) As will be clear to those with skill in the art, the herein illustrated and described embodiments of the present invention may be altered in various ways without departing from the scope or teaching of the present invention. It is the following claims, including all equivalents, which define the scope of the present invention.