Patent Application
20150330570
The present invention relates to vessels, for example, pressure containment vessels, which may be used to house components in a heating, ventilation, air conditioning and refrigeration (“HVACR”) system.
Pressure containment vessels are used in a variety of applications. In some high pressure applications, it is necessary to reinforce the outer walls of the pressure vessel.
Conventionally, the outer wall of the pressure vessel can be reinforced by wrapping the vessel with one or more layers of a rigid material (e.g., sheet metal) or by joining metal parts or segments to form an outer shell that surrounds the vessel. These techniques have some drawbacks, including, for example, difficulties with bending or forming the sheet metal around the vessel and difficulties caused by non-uniform material thicknesses which may make it difficult to closely surround the vessel with the reinforcement layer. Gaps between the reinforcement layer and the outer wall of the vessel are potential points of failure where the vessel may burst or crack. Additionally, such reinforcement techniques tend to be labor intensive.
As an alternative, the pressure vessel can be reinforced with a flexible or composite material, for example, a fiber reinforced material. This technique can add expense to the manufacturing process both in the form of costly materials and reduced manufacturing efficiency due to the general difficulty of working with such materials and increased time of assembly.
Another alternative for reinforcing pressure vessels is to increase the thickness of the outer wall of the vessel. This technique may not be suitable for some pressure vessels due to increased cost of raw materials and overall difficulties in working with thicker materials.
HVACR systems typically utilize pressure containment vessels (typically smaller-scale) that are spun from a copper tube. Such vessels can house various components of the system, such as check valves and/or filter/driers. Conventional HVACR systems use hydrofluorocarbon refrigerants that operate at pressures (e.g., less than about 200-300 psi) that are substantially below the burst pressure of a spun copper pressure containment vessel. In such systems, a spun copper pressure containment vessel is strong enough to provide adequate burst protection.
In recent years, there has been a push towards the use of refrigerants that are more environmentally friendly than conventional hydrofluorocarbon refrigerants. One such refrigerant is carbon dioxide. The use of carbon dioxide as a refrigerant requires the HVACR system to operate at significantly higher pressures (e.g., up to 1500 psi) as compared to the pressures in systems that use conventional hydrofluorocarbon refrigerants. To accommodate such refrigerants, the components of the system must be certified up to pressures in excess of 2100 psi. At such high pressures, larger-diameter components of the system, such as pressure containment vessels, can experience significantly higher hoop stresses than conventional HVACR systems were ever expected to tolerate.
Conventional reinforcement techniques may not be suitable for reinforcing pressure containment vessels in such systems. For example, along with other drawbacks, manufacturing costs may make it unreasonable or impractical to wrap the pressure containment vessel with one or more sheet metal or fiber-reinforced layers. Furthermore, as noted above, pressure containment vessels in HVACR systems typically are spun from a copper tube. While it may be possible to achieve necessary burst strengths by forming the containment vessel from thick-walled copper, such material may be difficult and/or expensive to obtain and also significantly more difficult to machine. Difficulties in machining, especially by spinning can lead to premature wear of tooling and decreased manufacturing productivity.
Additionally, a pressure containment vessel formed from a heavy-walled copper can be difficult to braze during installation of a HVACR system. When spun from heavy-walled copper, the ends of the pressure containment vessel, which form connections with the other components of the system, can be significantly thicker than conventional pressure containment vessels. The thick ends can function as heat sinks during the brazing process, making it difficult to form a reliable brazed connection. Furthermore, additional heat may be required to form the brazed connection. This can result in damage to the other components of the system, including, for example, components inside the pressure containment vessel.
The present invention provides pressure containment vessel having an improved burst strength that does not suffer from the same drawbacks of prior reinforcement techniques. The vessel described herein can withstand the higher pressures of alternative refrigerants used in HVACR systems and also can be manufactured in a cost-effective and efficient manner, for example, without welding or joining metal shell parts together to form an outer shell that surrounds the vessel.
According to one aspect, the present invention provides a vessel having a tubular body with a middle portion and a first tapered portion extending from a first end of the middle portion. The vessel has a monolithic reinforcement sleeve surrounding the tubular body. The reinforcement sleeve has a first tapered end portion adjacent to and surrounding at least part of the first tapered portion of the tubular member.
According to an embodiment, the tubular member includes a second tapered portion extending from a second end of the middle portion, and the monolithic reinforcement sleeve has a second tapered end portion adjacent to and surrounding at least part of the second tapered portion of the tubular member.
According to an embodiment, the first tapered end portion of the monolithic sleeve and the second tapered end portion of the monolithic sleeve are cold-formed. The tubular body may be a spun copper body. The tubular body may contain a HVACR component, such as a filter/drier or a check valve or may operate as a muffler for the system.
According to another aspect, the present invention provides a vessel with a tubular body having a middle portion and a pair of transitional sections extending from opposite ends of the middle portion. The transitional sections terminate at respective ends of the tubular body and have a cross-sectional area that is less than the cross-sectional area of the middle portion. The vessel has a sleeve closely surrounding the tubular body. The sleeve has a middle portion adjacent to the middle portion of the tubular body and a pair of end portions adjacent the transitional sections of the tubular body.
According to another aspect, the present invention provides a component for an HVAC system. The component has a shell having a cylindrical portion extending between respective end portions, an inlet at a first one of the end portions and an outlet at a second one of the end portions. The component includes a HVAC component inside the shell and a monolithic sleeve. The monolithic sleeve has a cylindrical portion that surrounds the cylindrical portion of the shell and a pair of respective cold formed end portions at least partially surrounding the respective end portions of the shell.
According to another aspect, the present invention provides a method of forming a component for an HVAC system. The method includes forming a tubular body with a central portion and a pair of tapered end portions extending from opposite ends of the central portion and reinforcing the tubular member by telescoping a monolithic tubular sleeve over the tubular body and reducing the diameter of respective end portions of the sleeve, the end portions of the sleeve being adjacent to respective tapered portions of the tubular body.
Embodiments of this invention will now be described in further detail with reference to the accompanying drawings, in which:
Referring initially to
The system 100 is charged with a refrigerant. The refrigerant may be a refrigerant that operates at a high pressure and/or an environmentally-friendly refrigerant. In one embodiment, the refrigerant is carbon dioxide (also referred to as R744). As noted above, systems that the use carbon dioxide refrigerant operate at significantly higher pressures than systems that use conventional hydrofluorocarbon refrigerants. Many conventional components of a HVACR system can withstand the higher operating pressures of alternative refrigerants, however, certain components of the system that have larger cross-sectional areas (such as a compressor or a pressure containment vessel 102, etc.) can be subject to very high hoop stresses from such refrigerants.
The pressure containment vessel 102 of
The tubular body 202 has a middle portion 206 which may be generally cylindrical in shape. Although other tubular shapes are possible, shapes having a circular cross-section tend to be able to withstand greater internal pressures due to the even distribution of forces.
Extending from either end of the middle portion 206 are transitional sections 208 and 210 which terminate at respective end portions 212 and 214 of the tubular body 202. One or both of the transitional sections may be tapered from the generally wider middle portion 206 to generally narrower end portions 212 and 214. As shown best in the cross-sectional view of
The tubular body 202 can be in the form of a shell and may be formed by a spinning process during which a length of tube is formed into the transitional sections 208 and 210. The metal tube may be a thin-walled tube and may, for example, have a thickness of less than about 0.035 inches. In one embodiment, the tubular member if formed from a copper tube having a 0.10 inch wall. The outer wall of the tubular body 202 may be thicker at the end portions 212 and 214 than at the middle portion 206. This may be the result of forming the tubular body 202 with the spinning process.
At either end of the tubular body are sockets 216 and 218. The sockets 216 and 218 can provide an inlet and an outlet, respectively, for a flow of fluid through the vessel. The sockets 216 and 218 can be coupled to respective extension members 220 and 222 for coupling the vessel to other component(s) of the system. For example, as shown in
One or both of the extension members 220 and 222 can have flared openings 224 and 226 that are suitable for brazing. For example, the one or both of the openings can be configured for forming a brazed connection with copper tubing that is commonly used in HVACR systems. In one embodiment, the extension members are formed from copper, which may be particularly useful when the vessel is installed as part of an HVACR system because the can eliminate the need for special brazing knowledge, materials, and skills for the user/installer. The flared openings 224 and 226 can define respective openings to the inside of the vessel. Fluid may flow into the vessel via one of the openings (e.g., opening 224) and out of the vessel via the other opening (e.g., opening 226).
Adjacent to and surrounding at least part of the tubular body 202 is the sleeve 204. The sleeve 204 can have a similar shape to the tubular member 202. The sleeve 204 may have a middle portion 240 adjacent to the middle portion 206 of the tubular body 202 and respective end portions 242 and 244 adjacent to and surrounding at least part of the transition portions 206 of the tubular body. One or both of the end portions 242 and 244 can be tapered such that the cross-sectional area of the sleeve 204 at the end portions 242 and 244 is less than the cross-sectional area of the sleeve 204 at the middle portion 240. The sleeve may be substantially the same length as the tubular member, or may be shorter than the tubular member. As shown in the embodiment of
The tubular body 202 and sleeve 204 can be assembled by telescoping the sleeve 204 over the tubular body 202 and reducing the diameter of the end portion(s) 242 and 244 of the sleeve that are adjacent to the tapered portion(s) 208 and 210 of the tubular body. In one embodiment, the end portion(s) of the sleeve are cold formed to the desired shape. For example, the end portion(s) can be cold formed by pressing the end portion axially until the end portion(s) of the sleeve closely match the shape of the transitional portion(s) of the tubular member.
The tubular body 202 and the sleeve 204 may be sized such that the sleeve 204 forms a slip fit with the tubular body leaving little to no space between the tubular body and the surrounding sleeve. For example, the inner diameter of the sleeve may be slightly larger than the outer diameter of the tubular member. In this manner, the tubular member 202 and the sleeve are closely fit to one another. When the tubular member is subjected to high internal pressures, the outer walls of the tubular member will be constrained from expansion by the sleeve. This increases the strength of the vessel and the hoop stress that the vessel can withstand. When the inside of the tubular member is pressurized, the tubular member may expand in the radial direction, however, the extent to which the tubular member can expand is constrained by the sleeve, thereby preventing a failure (such as a blowout) of the tubular member.
When assembled, the sleeve 204 closely surrounds the tubular body 202 thereby increasing the effective strength of the vessel such that the vessel can withstand higher internal pressures, e.g., the pressures associated with the use of alternative refrigerants. The phrase “closely surrounds” is intended to mean that the two components are touching or in such close proximity to one another that there is at most a small or insignificant gap between the components. By closely surrounding the tubular body, the sleeve can constrain the radial expansion of the tubular member when the tubular body is subjected to internal pressure. In one embodiment, the gap between the sleeve and the tubular component is less than about 0.25 inches. In another embodiment, the gap is less than about 0.1 inches. In another embodiment, the gap is less than 0.05 inches. In another embodiment, the sleeve and the tubular body are touching one another.
The sleeve 204 can be a monolithic sleeve. As used herein, “monolithic” means a substantially uniform as a whole. The monolithic sleeve may be formed from a tubular member, such as a metal tube, including but not limited to a welded tube or a seamless tube. The metal tube may be drawn or extruded to size. A wide variety of materials may be used for the monolithic structure (aluminum, copper, carbon steel, stainless steel, brass, etc).
Inside of the tubular body 202 may be any of a number of HVACR components, such as a filter-drier, desicant (such as beaded or molded core), check valve, strainer (such as a screen mesh strainer), noise attenuating baffles or muffler, and the like.
An embodiment of a pressure containment vessel 300 containing a filter-drier assembly is shown in
As shown in
Fluid can flow into the filter-drier via opening 324 and into the inside 350 of the tubular member 302. The fluid then passes though the baffle 354. The baffle 354 may keep loose desiccant contained during assembly and/or handling of the vessel, for example, by an end customer. The baffle also keeps the desiccant from churning due to refrigerant flow which may shorten the life of the product by attrition. The fluid then passes through the sieve 356, which may be a molecular sieve which removes moisture from the refrigerant by adsorption. From the sieve, the fluid passes through the screen assembly 358, which may capture harmful particulate contaminates in the refrigerant. From the screen assembly, the fluid exits the vessel 300 via the second opening 326.
Another embodiment of a pressure containment vessel 400 containing a HVACR component is shown in
The vessel 400 includes a tubular member 402 and a sleeve 404. The inside 450 of the tubular member 402 includes a check valve assembly 460. The check valve assembly 460 of
Another embodiment of a pressure containment vessel 500 is shown in
The vessel 500 includes a tubular member 502, a sleeve 504, and at least one intermediate layer 505. The intermediate layer 505 may be formed from a dielectric material. The dielectric material may be a flexible material. In one embodiment, the dielectric material is polyvinylchloride (PVC), and may, for example, be PVC heat shrink tubing. Other suitable materials may be used. The intermediate layer 505 can fill any extra space or gap between the tubular member 502 and the sleeve 504. Although shown only with respect to one embodiment, it should be appreciated that an intermediate layer can be added to any embodiment of the vessel.
Forming the vessel from two dissimilar metals can form a galvanic cell that will accelerate corrosion. The intermediate layer 505 can be formed from a dielectric material that electrically insulates the tubular member 502 from the sleeve 504. Additionally or alternatively, the sleeve in this or other embodiments may be anodized or otherwise treated to passivate the surface reduce potential corrosion.
Although the principles, embodiments and operation of the present invention have been described in detail herein, this is not to be construed as being limited to the particular illustrative forms disclosed. They will thus become apparent to those skilled in the art that various modifications of the embodiments herein can be made without departing from the spirit or scope of the invention.
This application claims the benefit of U.S. Provisional Application No. 61/636,758 filed Apr. 23, 2012, which is hereby incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2013/021679 | 1/16/2013 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 61636758 | Apr 2012 | US |
