Patent Application
20150276104
This document pertains generally, but not by way of limitation, to high pressure metal-metal joints and related methods of joining metal tubing.
Heating, Ventilation and Air Conditioning (“HVAC”) systems typically include metal tubing for communicating hot and cold water or refrigerants through the HVAC system. In particular, metal tubing is coiled with the heat exchangers of the HVAC system to facilitate maximum heat transfer between fluids or gases contained within the tubing and surrounding air or fluids while minimizing the overall footprint of the heat exchanger. The tubing conventionally comprises a plurality of copper tubing sections that are joined together to define a continuous fluid path. As the fluids or gases within the tubing are often under high pressures and/or relatively high or low temperatures, the joints between the tubing sections are brazed together to provide a joint capable of withstanding the necessary pressures and temperatures.
The use of aluminum tubing sections in place of copper tubing sections has recently increased. Similarly, copper tubing sections, in particular heat exchanger coils, of existing HVAC systems are frequently replaced with aluminum tubing sections during maintenance or repair. While copper have superior heat conductivity properties, aluminum is less expensive than copper providing a lighter and more cost effective material option. Similarly, unlike copper, aluminum does not develop formicary corrosion, which can cause leakage in the coils. In addition, aluminum can be more easily machined and shaped into configurations that compensate for or overcome the weaker heat conductive properties of aluminum. For example, aluminum can be shaped into micro-channel coils that have higher heat conductivity than conventionally shaped aluminum coils.
However, aluminum-aluminum connections or aluminum-copper connections can be more difficult to correctly braze than copper-copper connections. As the solidus temperature of aluminum is substantially lower than that of copper, the risk of over overheating the aluminum connection and accordingly weakening the connection is substantially higher. In addition, the lower solidus temperature of aluminum limits the filler materials or fluxes that can be used in the brazing of aluminum connections. With certain fluxes, the temperature difference between the liquidus temperature of the flux and the solidus temperature of the aluminum is relatively small providing a very small ideal temperature window for brazing aluminum connections. Similarly, unlike the phosphorus-containing filler materials used for brazing copper connections, the fluxes used to braze aluminum connections can leave a residue following brazing that can cause corrosion or otherwise weaken the brazed connection.
Accordingly, substantial care can be needed for brazing aluminum-aluminum and aluminum-copper connections, slowing the production of the aluminum components as well as increasing the cost. In addition, the high level of skill required as well as the unique equipment required to properly braze aluminum connections makes field installation of new HVAC systems or maintenance of existing HVAC systems particularly tedious.
The present inventors have recognized, among other things, that a problem to be solved can include efficiently forming secure joints between metal tubing sections that are capable of withstanding high pressures. In an example, the present subject matter can provide a solution to this problem such as by adhering a male end of a first tubing section within a female end of a second tubing section with an adhesive. A clamp can be tightened over the overlapping tubing section between the first and second tubing sections to reinforce the joint between the first and second tubing sections. The combination of the adhesive and clamp can provide a secure joint between the first and second tubing sections capable of withstanding pressures equal to and even surpassing brazed joints. A joint secured by the combination of adhesive and clamp has been found to surprisingly withstand pressures that burst the tubing section itself. In addition, as the adhesive and clamp can be installed with minimal tools and expertise, tubing sections having difficult to braze materials, such as aluminum, can be joined with an equivalent or superior joint in less time and with less difficulty.
In an example, a method for joining disparate tubing sections can include providing a first tubing section including a male end and providing a second tubing section including a female end. The method can also include applying an adhesive compound to at least one of an exterior surface of the male end of the first tubing section and an interior surface of the female end of the second tubing section. The method can also include inserting the male end of the first tubing section into the female end of the second tubing section to form an overlapping tubing section, wherein the adhesive compound is compressed between the male end of the first tubing section and the female end of the tubing section. The method can also include positioning a clamp over the female end such that the clamp is positioned within the overlapping tubing section when the male end of the first tubing section is inserted into the female end of the second tubing section. Finally, the method can include tightening the clamp to apply an inward circumferential force to the overlapping tubing section.
In an example, a system for joining disparate tubing sections can include a first tubing section including a male end; a tubing section including a female end; and a clamp. The male end of the first tubing section can be configured to be inserted into the female end of the second tubing section to form an overlapping tubing section. An adhesive compound can be applied to at least one of an exterior surface of the male end of the first tubing section and an interior surface of the female end of the second tubing section. The clamp can be positioned over the female end such that the clamp is positioned within the overlapping tubing section when the male end of the first tubing section is inserted into the female end of the second tubing section. The clamp can be tightened to apply an inward circumferential force to the overlapping tubing section.
This overview is intended to provide an overview of subject matter of the present patent application. It is not intended to provide an exclusive or exhaustive explanation of the present subject matter. The detailed description is included to provide further information about the present patent application.
In the drawings, which are not necessarily drawn to scale, like numerals may describe similar components in different views. Like numerals including different letter suffixes may represent different instances of similar components. The drawings illustrate generally, by way of example, but not by way of limitation, various embodiments discussed in the present document.
In an example, the present subject matter relates to a tubular joint 20 formed by inserting a male end 28 of a first tubing section 24 into a female end 32 of a second tubing section 24. An adhesive compound 36 is applied to the overlapping tubing section and a clamp 26 is used to apply an inward circumferential force to the overlapping tubing section. The clamping of the clamp 26 over the adhesively joined overlapping tubing section was found to provide superior joint than either adhering the joint with an adhesive compound or clamping the joint alone. In particular, the clamping reinforces the adhesive compound such that leaks are less likely at pressures nearing the burst pressure of the joint when adhered together with adhesive compounds. A similar advantage is that the clamp 26 can be positioned and tightened by rotating a nut 41 on a threaded screw 40, or vice versa, to draw the end portions 42 of the clamp 26 together. This arrangement allows the clamp 26 to be positioned and tightened without the aid of specialized tools or advanced training The simplicity of the installation increases the amount of the installation of an HVAC system that can be performed on site rather than at the factory.
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In an example, the outer surface 30 of the male end 28 can be textured to provide improved engagement of the adhesive compound 36 and to the inner surface 34 of the female end 32. In certain examples, the inner surface 34 of the female end 32 is alternatively or can also be textured to improve engagement of the adhesive compound 36 and to the outer surface 30 of the male end 28. In an example, the outer surface 30 of the male end 28 and the inner surface 34 of the female end 32 can be treated or cleaned to improve engagement of the adhesive compound 36 to the outer surface 30 of the male end 28 and the inner surface 34 of the female end 32. In an example, the outer surface 30 of the male end 28 includes at least one protrusion for engaging a corresponding notch in the inner surface 34 of the female end 32 to improve retention of the first tubing section 22 to the second tubing section 24. In a configuration, the inner surface 34 of the female end 32 alternatively or also includes at least one protrusion for engaging a corresponding notch in the outer surface 30 of the male end 28.
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In operation, the threaded screw 40 or the threaded nut 41 is rotatable in a first direction to draw the end portions 42 together and reduce an inner diameter of the bendable leaf 38. As depicted in
As depicted in FIGS. 4 and 12-13, in an example, the inner surface 44 includes a smooth surface. In this configuration, the inner surface 44 of the clamp 26 uniformly applies the inward circumferential force. In an example, the inner surface 44 includes a ribbed surface. In this configuration, the tightening the clamp 26 to apply the inward circumferential force crimps the female end 32 further reinforcing the joint between the first tubing section 22 and the second tubing section 24.
In an example, the first tubing section 22 and the second tubing section 24 include a metal, including, but not limited to aluminum, brass, copper, stainless steel, steel, alloys thereof and combinations thereof. In an example, the clamp 26 includes a rigid material, including, but not limited to aluminum, steel, nylon, polyvinyl chloride, high density polyethylene, low density polyethylene and other rigid materials. In certain examples, the clamp 26 is anodized or coated to prevent corrosion between the female end 32 of the second tubing section 24 and the inner surface 44 of the clamp 26.
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In an example, an HVAC system can be fitted with at least one tubular joint 20 including a first tubing section 22 having a male end 28 and a second tubing section 24 having a female end 32, in which the male end 28 of the first tubing section 22 is inserted into the female end 32 to form an overlapping tubing section. Prior to insertion, an adhesive compound 36 is applied to an outer surface 30 of the male end 28 and/or an inner surface 34 of the female end 32. A clamp 26 configured to be positioned over the overlapping tubing section can be tightened to apply an inward circumferential force to the overlapping tubing section to secure the first tubing section 22 to the second tubing section 24. The tubular joint 20 is configured to withstand high pressures of gases and fluids used in HVAC systems. The combination of adhesive compound 36 and the clamp 26 reduce the likelihood of the tubular joint 20 bursting or leaking.
Each of these non-limiting examples can stand on its own, or can be combined in any permutation or combination with any one or more of the other examples.
The above detailed description includes references to the accompanying drawings, which form a part of the detailed description. The drawings show, by way of illustration, specific embodiments can be practiced. These embodiments are also referred to herein as “examples.” Such examples can include elements in addition to those shown or described. However, the present inventors also contemplate examples in which only those elements shown or described are provided. Moreover, the present inventors also contemplate examples using any combination or permutation of those elements shown or described (or one or more aspects thereof), either with respect to a particular example (or one or more aspects thereof), or with respect to other examples (or one or more aspects thereof) shown or described herein.
In the event of inconsistent usages between this document and any documents so incorporated by reference, the usage in this document controls.
In this document, the terms “a” or “an” are used, as is common in patent documents, to include one or more than one, independent of any other instances or usages of “at least one” or “one or more.” In this document, the term “or” is used to refer to a nonexclusive or, such that “A or B” includes “A but not B,” “B but not A,” and “A and B,” unless otherwise indicated. In this document, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Also, in the following claims, the terms “including” and “comprising” are open-ended, that is, a system, device, article, composition, formulation, or process that includes elements in addition to those listed after such a term in a claim are still deemed to fall within the scope of that claim. Moreover, in the following claims, the terms “first,” “second,” and “third,” etc. are used merely as labels, and are not intended to impose numerical requirements on their objects.
The above description is intended to be illustrative, and not restrictive. For example, the above-described examples (or one or more aspects thereof) may be used in combination with each other. Other embodiments can be used, such as by one of ordinary skill in the art upon reviewing the above description. The Abstract is provided to comply with 37 C.F.R. §1.72(b), to allow the reader to quickly ascertain the nature of the technical disclosure. It is submitted with the understanding that it will not be used to interpret or limit the scope or meaning of the claims. Also, in the above Detailed Description, various features may be grouped together to streamline the disclosure. This should not be interpreted as intending that an unclaimed disclosed feature is essential to any claim. Rather, inventive subject matter may lie in less than all features of a particular disclosed embodiment. Thus, the following claims are hereby incorporated into the Detailed Description as examples or embodiments, with each claim standing on its own as a separate embodiment, and it is contemplated that such embodiments can be combined with each other in various combinations or permutations. The scope of the described subject matter should be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.
