Tubing is used to transport variety of fluids in various applications. Despite decades of research, there remains an unmet need for tubing that is resistant to chemically aggressive fluids, capable of withstanding vibration, pressures, and temperatures found in automobile and aircraft engines, and cost-effective.
One aspect of the invention provides a tube including a PTFE tube and a jacket circumferentially surrounding the PTFE tube. The jacket is formed from a plurality of plaits of fiberglass lace. The fiberglass lace includes PTFE.
This aspect of the invention can include a variety of embodiments. The jacket can be a braided jacket. The jacket can be sintered to the PTFE tube. The fiberglass lace can be formed from a plurality of strands of PTFE-coated fiberglass. Each of the plurality of plaits can be coated with PTFE after braiding.
The plurality of plaits can lie substantially flat with respect to longitudinal axis of the tube.
One or more of the plaits can include one or more reinforcing strands. The one or more reinforcing strands can be aramids. The one or more reinforcing strands can be para-aramids. The one or more reinforcing strands can be aromatic polyesters. One or more of the plaits can have a ratio of fiberglass strands to reinforcing strands between 1:1 and 20:1. One or more of the plaits can have a ratio of fiberglass strands to reinforcing strands of 7:1.
The PTFE tube can have an orientation index between 0.9 and 1.0.
An innermost portion of the PTFE tube can be conductive. An innermost 10% of the PTFE tube can contain between about 0.5% to about 2.5% conductive particles by weight. The innermost 10% of the PTFE tube can contain between about 1.5% conductive particles by weight.
The fiberglass lace can include conductive particles. The tube can be dipped in a dispersion of conductive particles.
The conductive particles can be carbon black.
The fiberglass can be S-Glass. The fiberglass can be E-Glass.
Another aspect of the invention provides a method of producing a tube. The method includes: providing a PTFE tube and forming a jacket by circumferentially wrapping a plurality of plaits of fiberglass lace around the PTFE tube. The fiberglass lace includes PTFE.
This aspect of the invention can have a variety of embodiments. The forming step can include braiding the plurality of plaits around the PTFE tube. The fiberglass lace can be formed from a plurality of strands of PTFE-coated fiberglass. Each of the plurality of plaits can be coated with PTFE after braiding.
The PTFE tube can be formed by extrusion. The PTFE tube can be formed by vertical extrusion.
The method can further include sintering the tube to bond the PTFE tube to the braided jacket. The sintering step can include introducing the tube into an oven so that the tube is heated to between about 700° F. and about 725° F. The tube can be exposed to the oven for a sufficient period of time to hold the tube at a temperature between about 700° F. and about 725° F. for about 3 minutes.
The method can further include dipping the tube in a dispersion of conductive particles.
Another aspect of the invention provides a tube prepared by any of the methods described herein.
Another aspect of the invention provides a method of using a tube. The method includes: providing a tube as described herein and coupling one or more ends of the tube to one or more devices.
For a fuller understanding of the nature and desired objects of the present invention, reference is made to the following detailed description taken in conjunction with the accompanying drawing FIGS. wherein like reference characters denote corresponding parts throughout the several views and wherein:
The instant invention is most clearly understood with reference to the following definitions:
As used herein, the singular form “a, ” “an,” and “the” include plural references unless the context clearly dictates otherwise.
Unless specifically stated or obvious from context, as used herein, the term “about” is understood as within a range of normal tolerance in the art, for example within 2 standard deviations of the mean. “About” can be understood as within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise clear from context, all numerical values provided herein are modified by the term about.
As used herein, the terms “comprises,” “comprising,” “containing,” “having,” and the like can have the meaning ascribed to them under U.S. patent law and can mean “includes,” “including,” and the like.
Unless specifically stated or obvious from context, the term “or,” as used herein, is understood to be inclusive.
Ranges provided herein are understood to be shorthand for all of the values within the range. For example, a range of 1 to 50 is understood to include any number, combination of numbers, or sub-range from the group consisting of 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, or 50, as well as all intervening decimal values between the aforementioned integers such as, for example, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, and 1.9. With respect to sub-ranges, “nested sub-ranges” that extend from either end point of the range are specifically contemplated. For example, a nested sub-range of an exemplary range of 1 to 50 may comprise 1 to 10, 1 to 20, 1 to 30, and 1 to 40 in one direction, or 50 to 40, 50 to 30, 50 to 20, and 50 to 10 in the other direction.
Referring now to
Inner tube 102 can be composed of a polymer, for example, a fluoropolymer such as polytetrafluoroethylene (PTFE). In some embodiments, the inner tube is completely or partially conductive. For example, an innermost portion of the inner tube 102 (i.e., the inner surface adjacent to a longitudinal axis of the inner tube 102) can be conductive. The thickness of this innermost portion can be defined as a percentage of the thickness of the inner tube 102 can, for example, an innermost 5%, 10%, 15%, 20%, 25%, and the like. Inner tube 102 or a portion thereof can be rendered conductive by the incorporation of metal particles (e.g., copper, aluminum, gold, silver, nickel, and the like), carbon black, carbon fibers, or other conductive additives.
Referring to
The conductivity of the innermost region 206 can be controlled by varying the amount of conductive particles added to the polymer. In some embodiments, the innermost region 206 contains between about 0.5% and about 2.5% conductive particles by weight, between about 1.5% and about 2.5% conductive particles by weight, and the like.
The inner tube can, in some embodiments, have a high orientation index, which is a measure of the degree of orientation of the PTFE chains in the longitudinal direction versus that of the transverse direction. An orientation index of zero (0) means that the PTFE chains are randomly oriented. An orientation index of one (1) means that all of the PTFE chains are oriented in the longitudinal direction.
The inner tube 102 can be completely formed and/or cured before the jacket 104 is applied over the inner tube 102.
Jacket 104 can be formed from a plurality of plaits 106 of fiberglass lace. The fiberglass lace, in turn, can incorporate PTFE. Suitable fiberglass lace is available under the A-A-52083 (Type IV) specification from a variety of sources including Breyden Products, Inc. of Columbia City, Ind.; Western Filament, Inc. of Grand Junction, Colo.; and W.F. Lake Corp. of Glens Falls, N.Y.
In some embodiments, the underlying fiberglass strands include of E-glass or S-glass. E-glass and S-glass are widely available from a variety of source. Generally speaking, E-glass is understood to refer to alumina-calcium-borosilicate glasses used as a general purpose reinforcement where strength and high electrical resistivity are desired, while S-glass is understood to refer to magnesium aluminosilicate glasses used for textile substrates or reinforcement in composite structural applications that require high strength, modulus, and durability under conditions of extreme temperature or corrosive environments. A variety of other types of fiberglass can be used including AR-glass, C-glass, D-glass, E-CR-glass, R-glass, and the like.
In some embodiments, the jacket 104 is braided as depicted in
PTFE can be incorporated into the plaits 106 in a variety of manners. In one embodiments, each plait 106 is formed from a plurality of fiberglass strands, each of which individually coated with PTFE prior to braiding. In another embodiment, the braided plait 106 is dipped in PTFE to coat the braided plait 106.
Each plait 106 can have a substantially rectangular cross-section. That is, each plait 106 can have a width substantially greater than a height. In such an embodiment, the plaits 106 can be arranged in the braided jacket such that the wider side of the plaits 106 contacted inner tube 102. Such an arrangement minimizes the thickness of braided jacket 104 and provides more structural support to inner tube 102.
Each plait 106 can be formed from a plurality of individual strands of fiberglass. For example, each plait 106 can be formed from between 5 and 19 strands.
One or more reinforcing strands can be incorporated one or more of the plaits 106. For example, one or more aramid, para-aramid, or aromatic polyester strands can be braided along with the fiberglass strands. Suitable aramids and para-aramids are sold under the KEVLAR® brand by E. I. du Pont de Nemours and Company of Wilmington, Del., under the TECHNORA® brand by Teijin Limited of Osaka, Japan, and under the TWARON® brand by Teijin Aramid B. V. of Arnhem, The Netherlands. Suitable aromatic polyesters are available under the VECTRAN® and VECTRAN® EX brands from Kuraray America, Inc. of Fort Mill, S.C. The ratio of fiberglass strands to reinforcing strands can, for example, be between 1:1 and 20:1.
The jacket 104 can be conductive. For example, the jacket 104 can include a plurality of conductive particles such as metal particles (e.g., copper, aluminum, gold, silver, nickel, and the like), carbon black, carbon fibers, or other conductive additives. Such particles can be present in the individual strands of fiberglass, applied to the fiberglass plaits 106, and/or applied to the jacket 104 after formation. For example, any of the strands, plaits 106, or jacket 104 can be dipped in a dispersion of conductive particles, which are then retained.
The jacket 104 can be sintered to the inner tube 102 to provide structural stability that prevents the inner tube 102 from collapsing, deforming, or bursting as will be discussed in greater detail below.
Referring now to
In step S302, a PTFE tube is provided. The PTFE tube can be fabricated or can be obtained from a variety of sources. In some embodiments, the PTFE tube is formed by extrusion. Advantageously, PTFE tubes can be formed by vertical extrusion, in which the tube is extruded downward through a die (instead of the usual horizontal extrusion) in order to produce a tube with a high orientation index as discussed herein. Suitable vertically-extruded PTFE tubes are available from Titeflex Corporation of Springfield, Mass. Alternatively, the PTFE tube can be annealed (e.g., while hanging vertically) to increase the orientation index. This annealing step can be performed prior to the braiding step.
In step S304, a jacket is circumferentially wrapped around the PTFE tube. In some embodiments, the jacket is a braided. In other embodiments the jacket is helically wrapped. The jacket can be formed from a plurality of plaits of fiberglass lace using standard braiding and rope making techniques and equipment. As discussed above, the fiberglass lace can include PTFE and/or one or more reinforcing strands.
In step S306, the assembled tube is optionally exposed to a dispersion of conductive particles to impart a conductive property on the jacket.
In step S308, the assembled tube is optionally sintered to bond the PTFE tube to the braided jacket. The sintering step can include introducing the tube into an oven so that the tube is heated to between about 700° F. and about 725° F. The speed, length, and/or temperature of the oven can be controlled so that the tube is held at this temperature from between about 2 minutes and about 4 minutes (e.g., about 3 minutes).
Referring now to
In step S402, a tube is provided. The tube can be of the types described
herein.
In step S404, one or more fittings can be coupled with one or more ends of the tube. The fittings can, for example, be of conventional types used in the automotive and aerospace industries.
In step S406, one or more ends of the tube are coupled to one or more devices. For example, a first end of a tube can be connected to a fuel source (e.g., a fuel tank or a fuel pump) while a second end of the tube is connected to a fuel sink (e.g., a fuel pump, a carburetor, or a fuel injector). In another example, a first end of the tube can be connected to a braking master cylinder and a second end of the tube can be connected to a braking slave cylinder. In still another example, a first end of the tube can be connected to an engine and a second end of the tube can be connected to a radiator.
Referring now to
While certain embodiments according to the invention have been described, the invention is not limited to just the described embodiments. Various changes and/or modifications can be made to any of the described embodiments without departing from the spirit or scope of the invention. Also, various combinations of elements, steps, features, and/or aspects of the described embodiments are possible and contemplated even if such combinations are not expressly identified herein.
The entire contents of all patents, published patent applications, and other references cited herein are hereby expressly incorporated herein in their entireties by reference.
This application claims priority to U.S. Provisional Patent Application Ser. Nos. 61/642,172 and 61/642,181, both filed on May 3, 2012. The entire contents of each of these applications is hereby incorporated by reference herein.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US2012/046053 | 7/10/2012 | WO | 00 | 8/28/2015 |
Number | Date | Country | |
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61642181 | May 2012 | US | |
61642172 | May 2012 | US |