GAS IMPERMEABLE TUBE JOINT AND METHOD OF FORMING SAME
A method of forming a gas impermeable joint in a fluid system includes: providing a tube having a metallic barrier layer disposed between an inner plastic layer and an outer plastic layer; forcing at least one of the inner plastic layer and the outer plastic layer into contact with a plastic surface of a component; and welding the at least one of the inner plastic layer and the outer plastic layer with the plastic surface to form the gas impermeable joint. The welding may include: spin welding, hot plate welding, vibration welding, and ultrasonic welding. The metallic barrier layer extends substantially to the component, thus improving the gas impermeability of the joint between the tube and the component.
This invention relates to the joining of tubes to other components in fluid systems. More specifically, this invention relates to gas impermeable tube joints and methods for forming gas impermeable tube joints in fluid systems.
In general, fluid systems serve to contain a fluid (e.g., a liquid, vapor, gas) as it is transported from one location to another. Fluid systems typically include a number of components interconnected by one or more tubes, which transport the fluid between the components. The components and tubes are connected together by joints, which allow the fluid to flow between the components and tubes while preventing leakage of the fluid from the system.
For certain fluid systems, it is important to prevent the infiltration or escape of the fluid in its gaseous state. One such fluid system, for example, is a fuel fill system in a motor vehicle, through which fuel is delivered to a storage tank. The escape of fuel vapor from fuel fill systems can be hazardous to the environment, and as a result, the U.S. Environmental Protection Agency prescribes limits to the amount of fuel vapor that may escape from the filler pipe. Another example of such a fluid system, is a radiant heating system found in homes and businesses. Often times hoses in a radiant heating system supply water or other heating fluid to heat exchangers located in floors, ceilings, roofs, and concrete or asphalt slabs. The hoses may be embedded in the surfaces to be heated. A significant problem with such hoses is that they are subject to gas infiltration and exfiltration. Oxygen is particularly troublesome because it is able to penetrate all known plastic films, at least to some small degree. Once oxygen has gained entry to such a heating system, it deteriorates the hoses and corrodes the pumping system. These are only a few examples of systems requiring gas impermeable tube joints and there are myriad fluid systems for which the prevention of the infiltration or escape of gas is critical to operation.
One way to reduce the infiltration or escape of gas in a fluid system is through the use of tubes having metallic barrier layers. For example, U.S. Pat. No. 6,074,717 to Little et al., describes a flexible hose that has an aluminum barrier layer for preventing ingestion of oxygen and other gasses. The aluminum barrier layer is securely bonded between two adhesion tubes which are vulcanized in place against the aluminum. The resulting tube is flexible and substantially gas impermeable. While such tubing is sufficiently gas impermeable to prevent the permeation of gas along the tube, the joints between tubes and components remain an area where the infiltration or escape of gas can occur.
Typically, the joints in such fluid systems are formed by sliding the tube over a projection on the component, and securing the tube in-place by way of a barb formed on the projection and/or a mechanical fastener (e.g., a hose clamp). Problematically, this method may allow for the permeation of gas through the joint connection. If the tube has a metallic layer, the permeation may be worse because of the relative inflexibility of the tube material and the resulting inability of the tube to form a tight fit with the projection.
Thus, there is a need for gas impermeable tube joints and methods for forming gas impermeable tube joints in fluid systems.
BRIEF SUMMARY OF THE INVENTIONThe above-described and other drawbacks and deficiencies of the prior art are overcome or alleviated by a method of forming a gas impermeable joint in a fluid system. The method includes: providing a tube having a metallic barrier layer disposed between an inner plastic layer and an outer plastic layer; forcing at least one of the inner plastic layer and the outer plastic layer into contact with a plastic surface of a component; and welding the at least one of the inner plastic layer and the outer plastic layer with the plastic surface to form the gas impermeable joint. The welding may include: spin welding, hot plate welding, vibration welding, and ultrasonic welding.
In one embodiment, the component includes a recess disposed therein, the recess being dimensioned to receive an end of the tube, and the plastic surface of the component being formed within the recess to contact at least one of the inner plastic layer and the outer plastic layer. In another embodiment, the component includes a cylindrical protrusion, the plastic surface being formed on either the outer circumference or the inner circumference of the cylindrical protrusion.
The thickness of the inner plastic layer and the outer plastic layer before welding is preferably greater than about 0.6 millimeters, and more preferably greater than about 1 millimeter. The thickness of the inner plastic layer and the outer plastic layer before welding may be between about 0.6 millimeters and 1.5 millimeters, and more preferably between about 1 millimeter and 1.2 millimeters.
The details of one or more embodiments of the invention are set forth in the accompanying drawings and the description below. Other features, objects and advantages of the invention will be apparent from the description and drawings, and from the claims.
BRIEF DESCRIPTION OF THE DRAWINGSThe invention will be more fully understood from the following detailed description taken in conjunction with the accompanying drawings wherein like elements are numbered alike, and in which:
Referring to
The inner and outer plastic layers 20, 22 of the tube 14 may be formed from any thermoplastic material. For example, the inner and outer plastic layers 20, 22 may be formed from polyethylene, polypropylene, acetals, nylons, fluoropolymers, rubbers, and combinations, composites, or multiple layers of any of the foregoing. The metallic layer 18 may be formed from any metal in sufficient quantity to prevent permeation of gas into or out of the system 10. Preferably, the metallic layer 14 is formed from a malleable metal such as aluminum, steel, tin, copper, brass, or combinations or alloys formed from one or more of the foregoing.
One example of a tube 14 that may be used with the present invention is described in U.S. Pat. No. 6,074,717, which is incorporated by reference herein in its entirety. The '717 patent describes a tube wherein the inner plastic layer 20 is formed by a first tube, the metallic barrier 18 is formed by an aluminum foil bonded exteriorly about the first tube, and the outer plastic layer 22 is formed by a second tube bonded exteriorly about the aluminum foil. The aluminum foil may be between about 0.0005 and 0.030 inches thick. The first tube and the second tube (i.e., inner and outer plastic layers 20, 22) each comprise about 20 percent by weight of ethylene propylene diene polymethylene (EPDM) rubber and from about 2 to 9 percent by weight of polybutadiene-maleic anhydride adduct resin. The formulation preferably includes about 2-8 percent by weight of active peroxide as a curing agent. The peroxide cure is performed in any conventional manner at a temperature of about 325° F., and provides a strong bond between the aluminum metallic barrier layer 18 and the inner and outer layers 20, 22. Suitable conventional black and non-black filler ingredients, and paraffinic or naphthenic plasticizers may be added to the mixture as desired. In addition, one or more reinforcement layers (not shown) may be added to the outer surface of the outer plastic layer 22. The reinforcement layer may be fabricated from, for example, rayon, polyester, polyvinyl acetate, wire, aramid, or any other suitable material. The reinforcement layer may also include a cover selected from any of numerous thermosetting elastomeric compounds such as natural rubber, styrene butadiene, polychloroprene, acrylonitrile butadiene, chlorosulfonated monomer, or chlorinated polyehtelene. Where the outer plastic layer 22 is used to form the weld, a portion of the reinforcement layer will be removed to expose the outer plastic layer 22 for welding.
Referring to
The component 16 may be molded from a plastic material such that one or more of the surfaces 32, 34 form the one or more plastic surfaces to which the tube is welded. Alternatively, the plastic surfaces 32 and/or 34 may be formed by inserts secured to the component 16.
The recess 30 has a depth “d”, which is the effective depth of the weld. As a result, the depth “d” of the recess may be used to control the strength of the joint 12 (
The width “w” of the recess, as well as the outside diameter of the inner protrusion 26 and the inside diameter of the outer protrusion 28, may be selected in relation to the dimensions of the tube 14 to determine which of the surfaces 32, 34 and layers 20, 22 form the weld. For example, these various dimensions may be selected such that the inner plastic layer 20 contacts the outer surface 32 of the inner protrusion 26, and the outer plastic layer 22 contacts the inner surface 34 of the outer protrusion 28, as shown in
In
Each of the arrangements in
The shoulder 82 may be of various shapes. For example, the shoulder 82 and the outer protrusion 28 may include opposing recesses 84 formed therein, as shown in
The present invention uses the metallic barrier layer 18 of a tube 14 to improve the gas impermeability of the joint 12 between the tube 14 and a component 16. Advantageously, because the weld is formed with the outer and/or inner plastic layers 20, 22 of the tube 14, the metallic barrier layer 18 extends substantially to the component 16, thus improving the gas impermeability of the joint 12 between the tube 14 and the component 16. The joint 12 is also lightweight and corrosion resistant.
A number of embodiments of the present invention have been described. Nevertheless, it will be understood that various modifications may be made without departing from the spirit and scope of the invention. Accordingly, other embodiments are within the scope of the following claims.
Claims
1. A method of forming a gas impermeable joint in a fuel fill system, the method comprising:
- providing a tube having a metallic barrier layer disposed between an inner plastic layer and an outer plastic layer, the tube and the layers each having a circumference, the outer plastic layer including a shoulder protruding radially outward around at least a portion of its circumference;
- forcing at least one of the inner plastic layer and the outer plastic layer into contact with a plastic surface of a funnel portion of the fuel fill system, the funnel portion including an outer protrusion portion surrounding a cylindrical recess, the recess being dimensioned to receive an end of the tube, the plastic surface of the funnel portion being formed within the recess to contact the at least one of the inner plastic layer and the outer plastic layer, the plastic surface of the funnel portion also being formed on the outer protrusion portion to contact the shoulder of the outer plastic layer;
- causing at least one of the inner plastic layer and the outer plastic layer to contact the plastic surface formed within the recess;
- causing the shoulder of the outer plastic layer to contact the plastic surface formed on the outer protrusion portion, and
- welding at least one of the at least one of the inner plastic layer and the outer plastic layer and the shoulder of the outer plastic layer with the plastic surface to form the gas impermeable joint.
2. (canceled)
3. (canceled)
4. The method of claim 1, wherein the plastic surface is formed on an outer circumference of the outer protrusion.
5. The method of claim 1, the plastic surface is formed on an inner circumference of the outer protrusion.
6. The method of claim 1, wherein the thickness of the at least one of the inner plastic layer and the outer plastic layer before welding is greater than about 0.6 millimeters.
7. The method of claim 6, wherein the thickness of the at least one of the inner plastic layer and the outer plastic layer before welding is greater than about 1 millimeter.
8. The method of claim 1, wherein the thickness of the at least one of the inner plastic layer and the outer plastic layer before welding is between about 0.6 millimeters to about 0.3 millimeters.
9. The method of claim 1, wherein the thickness of the at least one of the inner plastic layer and the outer plastic layer before welding is between about 1 millimeters to about 3 millimeters,
10. The method of claim 1, wherein the inner plastic layer is formed by a first tube, the metallic barrier is formed by an aluminum foil bonded exteriorly about the first tube, and the outer plastic layer is formed by a second tube bonded exteriorly about the aluminum foil; the first tube and the second tube each comprising about 20 percent by weight of EPDM rubber and from about 2 to 9 percent by weight of polybutadiene-maleic anhydride adduct resin.
11. The method of claim 1, wherein the tube includes a reinforcement layer bonded exteriorly about the outer plastic layer.
12. A fuel fill system comprising:
- a tube having a metallic barrier layer disposed between an inner plastic layer and an outer plastic layer, the tube and the layers each having a circumference, the outer plastic layer including a shoulder protruding radially outward around at least a portion of its circumference; and
- a funnel portion in fluid communication with the tube via a joint, the funnel portion including an outer protrusion portion surrounding a cylindrical recess, the recess being dimensioned to receive an end of the tube, a plastic surface of the funnel portion being formed within the recess to contact the at least one of the inner plastic layer and the outer plastic layer, the plastic surface of the funnel portion also being formed on the outer protrusion portion to contact the shoulder of the outer plastic layer, wherein at least one of the inner plastic layer and the outer plastic layer includes a spin weld between it and the plastic surface of the funnel portion to form the joint.
13. (canceled)
14. (canceled)
15. The system of claim 12, wherein the plastic surface is formed on an outer circumference of the outer protrusion.
16. The system of claim 12, wherein the plastic surface is formed on an inner circumference of the outer protrusion.
17. The system of claim 12, wherein the thickness of the at least one of the inner plastic layer and the outer plastic layer before welding is greater than about 0.6 millimeters.
18. The system of claim 17, wherein the thickness of the at least one of the inner plastic layer and the outer plastic layer before welding is greater than about 1 millimeter.
19. The system of claim 12, wherein the thickness of the at least one of the inner plastic layer and the outer plastic layer before welding is between about 0.6 millimeters to about 3 millimeters.
20. The system of claim 19, wherein the thickness of the at least one of the inner plastic layer and the outer plastic layer before welding is between about 1 millimeters to about 3 millimeters.
21. The system of claim 12, wherein the inner plastic layer is formed by a first tube, the metallic barrier is formed by an aluminum foil bonded exteriorly about the first tube, and the outer plastic layer is formed by a second tube bonded exteriorly about the aluminum foil; the first tube and the second tube each comprising about 20 percent by weight of EPDM rubber and from about 2 to 9 percent by weight of polybutadiene-maleic anhydride adduct resin.
22. The system of claim 12, wherein the tube includes a reinforcement layer bonded exteriorly about the outer plastic layer.
Type: Application
Filed: Dec 10, 2003
Publication Date: Jun 16, 2005
Inventors: John Mobley (Lexington, TN), Michael Thurston (Lexington, TN), Christopher Smith (Lexington, TN)
Application Number: 10/732,841