US20090159247A1

US20090159247A1 - Tube assemblies and combo-coolers incorporating the same

Info

Publication number: US20090159247A1
Application number: US11/963,185
Authority: US
Inventors: Brian Kendall; Zaiqian Hu; Didier Smith
Original assignee: Valeo Inc
Current assignee: Valeo Inc
Priority date: 2007-12-21
Filing date: 2007-12-21
Publication date: 2009-06-25

Abstract

A tube assembly includes at least a first tube and a second tube. A separator is positioned between the first tube and the second tube. A layer including silicon and a fluxing agent is established on at least a portion of each of the first and second tubes, the layer.

Description

BACKGROUND

The present disclosure relates generally to tube assemblies and combo-coolers incorporating such tube assemblies.
Two goals for heat exchanger manufacturing often include forming a product that exhibits efficient transfer of heat, while maintaining a relatively simple manufacturing process. In the automotive industry, in particular, it has also become desirable to combine multiple functions into a single heat exchanger assembly. Combo-coolers and tri-coolers are examples of such assemblies, and each includes multiple coolers (non-limiting examples of which include oil coolers, condensers, etc.). In a combo- or tri-cooler, the tubes of each cooler are connected to the same pair of manifolds or end tanks. The coolers are often formed having a tube and fin structure, in part because of cost efficiency and ease of assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

Features and advantages of embodiments of the present disclosure will become apparent by reference to the following detailed description and drawings, in which like reference numerals correspond to the same or similar, though perhaps not identical, components. For the sake of brevity, reference numerals having a previously described function may or may not be described in connection with subsequent drawings in which they appear.

FIG. 1 is a schematic view of an embodiment of a tube assembly; and

FIG. 2 is a schematic view of an embodiment of a combo cooler incorporating an embodiment of the tube assembly.

DETAILED DESCRIPTION

It is desirable to configure combo- and tri-coolers including air conditioning condensers and oil coolers to maximize the heat transfer of the fluids with different properties and operating conditions. In order to achieve this, the tubes of the condenser portion are often configured differently from the tubes of the oil cooler portion (e.g., the oil cooler tubes are much larger than the condenser tubes). Furthermore, separators (e.g., fins) including a base material with clad layers thereon have been used to separate the various tubes. The present inventors believe that the difference in tube geometry, creates a rigidity gradient in which the structure is more rigid near the oil cooler tube(s) and less rigid near the condenser tube(s). It is further believed that this rigidity gradient causes the condenser tube(s) and adjacent separators to be relatively weak and susceptible to bending and/or deformation, for example, when exposed to brazing temperatures. At brazing temperatures, the clad may also become liquid, thereby reducing the thickness of the separator and decreasing its strength. It is believed that this decrease in thickness and strength increases the rigidity gradient and thus the potential for deformation.
Embodiments of the tube assembly disclosed herein advantageously include a layer established on each of the tubes. It is believed that the addition of these layers enable the clad layer to be eliminated from the separator (i.e., from between the tubes), thereby substantially avoiding reduction of thickness and strength of the separator, eliminating the need to remove lubricants from between the tubes, and increasing the strength of the tube assembly and combo-cooler in which it is incorporated.
Referring now to FIG. 1, an embodiment of the tube assembly 10 is disclosed. The tube assembly 10 generally includes at least a first tube 12 and a second tube 14 and a separator 16 positioned therebetween.
The first and second tubes 12, 14 may be formed of any suitable material, including copper and copper alloys, aluminum and various aluminum alloys. Additionally, the tubes 12, 14 may be formed of a variety of materials including plastics, metals, carbon, graphite, other formable materials, or the like, or combinations thereof. More specific non-limiting examples of suitable tube 12, 14 materials include a metal selected from copper, copper alloys, low carbon steel, stainless steel, aluminum alloys, titanium alloys, magnesium alloys, or the like, or combinations thereof.
Furthermore, the tubes 12, 14 may have any suitable configuration, including a substantially oblong or oval shape. Formation of tubes 12, 14 may be accomplished using several different techniques. As non-limiting examples, the tubes 12, 14 may be drawn, rolled, cast, or otherwise formed.
In one embodiment of the tube assembly 10, one of the tubes 12, 14 (or plurality of tubes) is an oil cooler tube, and another of the tubes 14, 12 (or plurality of tubes) is a condenser tube. Such tubes may be particularly desirable when using the tube assembly 10 in a combo- or tri-cooler 100, as shown in FIG. 2.
The tubes 12, 14 may have the same or different internal configurations for defining fluid passages therein. The tubes 12, 14 may also have the same or different external configurations defining one or more outer peripheral surfaces. It is contemplated that the internal configurations and/or external configurations may vary along the length of the tubes 12, 14. Furthermore, the internal configuration of the tubes 12, 14 may be the same or different from the external configuration. Non-limiting examples of internal and external configurations includes grooves, ridges, bosses, or other like structures integrated along some or all of the tube 12, 14 length for assisting in heat transfer and/or for adding strength to the structure
The internal configurations may also generate turbulence within the fluid, or otherwise control the nature of the flow of fluid therethrough. In other embodiments, the internal configuration of the tubes 12, 14 may be smooth, planar, grooved, ridged, contoured (e.g., including several patterned ridges), ribbed (i.e., including several protrusions), dimpled (e.g., including several depressions) or the like.
In still other embodiments, the tubes 12, 14 may include one or more internal inserts, which are fabricated separately from the tubes 12, 14 and are assembled therein. It is contemplated that inserts may be formed in a variety of configurations and shapes for insertion into the fluid passages or portions of fluid passages. As a non-limiting example, the inserts may be members (e.g., straight or contoured members) with complex or simple configurations. Alternatively, inserts may be coils, springs or the like.
The fluid passages of the tubes 12, 14 may have any suitable configuration, including square, rectangular, circular, elliptical, irregular, or the like. The fluid passages of the tubes 12, 14 may also include one or more partitions, fins or the like. Furthermore, the fluid passage(s) of one tube 12 may be different than the fluid passage(s) of another tube 14 in the assembly 10.
The tubes 12, 14 may also have the same or different hydraulic diameters, widths and/or lengths. In some instances, some of the tubes 12, 14 may have different hydraulic diameters. The hydraulic diameter is generally configured to obtain maximum effectiveness of the exchanger element. As used herein, the hydraulic diameter (D_H) is determined according to the following equation:
D _H=4A _P /P _w
wherein
A_p=wetted cross-sectional area of the passageway of a tube; and
P_w=wetted perimeter of the tube.
Each of the variables (P_wand A_p) for the hydraulic diameter (D_H) are determinable for a tube 12, 14 according to standard geometric and engineering principles and will depend, at least in part, upon the configuration of a particular tube 12, 14 and the aforementioned variables for that tube 12, 14 (i.e., the number of partitions, the number of portions, the size of the portions, the size of the fluid passages, or combination thereof).
Heat transfer and pressure drop for a fluid flowing through the tubes can be determined for a range of hydraulic diameters using sensors such as pressure gauges, temperature sensors or the like.
Each of the tubes 12, 14 has a layer 18 established thereon. Each of the layers 18 includes at least silicon and a fluxing agent. The silicon is generally in the form of powder. It is believed that the presence of silicon in the layers 18 advantageously enables clad layers to be eliminated from the separator 16 without compromising the ability to braze the tubes 12, 14 to the separator 16.
The fluxing agent is generally one that is configured for brazing aluminum or other metal components (e.g., the tubes 12, 14 and the separator 16) together. A non-limiting example of such a fluxing agent is commercially available under the tradename NOCOLOK®, from Solvay Fluor, located in Hannover, Germany. Another suitable fluxing agent is a flux containing zinc. It is believed that a fluxing agent containing zinc advantageously provides enhanced protection against tube corrosion.
A binder may also be added to the layers 18. A non-limiting example of such a binder includes a synthetic resin, such as that described in U.S. Pat. No. 6,800,345.
The layer 18 composition is generally formed by mixing predetermined amounts of the silicon, the fluxing agent and the binder. It is to be understood that the amounts may vary as is desired and may depend, at least in part, on the desirable properties for the layer 18.
Once the composition/mixture is formed, the composition/mixture is established on the exterior of each of the tubes 12, 14 to form layers 18. Any suitable deposition technique may be used to establish the composition/mixture on the tubes 12, 14. Non-limiting examples of such deposition techniques include, but are not limited to coating processes, roller coating processes, spraying processes, or the like.
The tubes 12, 14 having the layer 18 thereon may also be exposed to drying processes and/or sizing processes, as is desired.
The layer 18 is generally established to cover the entire exterior of each tube 12, 14. It is to be understood, however, that predetermined portions of the tube 12, 14 exterior may also be covered with the layer 18. As a non-limiting example, flat portions of the tube(s) 12, 14 may be covered with the layer 18, while rounded or curved portions of the tube(s) 12, 14 remain uncovered.
After the tubes 12, 14 are covered with respective layers 18, the separator 16 is established between the covered tubes 12, 14. The separator 16 and tubes 12, 14 may be brazed together. One non-limiting example of such a brazing technique is controlled atmosphere brazing. It is believed that the layers 18 may act as a brazing alloy for attaching the components. The layers 18 are heated and melted (e.g., in an oven or furnace, and often under a controlled atmosphere). Upon cooling, the layers 18 form a metallurgical bond with the components, thereby attaching the components together. As such, the layers 18 provide a means for bonding respective tubes 12, 14 to adjacent separators 16.
The separator 16 may be formed of any suitable material. A non-limiting example of such a material is an aluminum alloy. Examples of such aluminum alloys include, but are not limited to AA 1000 series alloys and AA 5000 series alloys. It is to be understood that any other material that is compatible with brazing conditions may be used.
In an embodiment, the separator 16 includes a plurality of fins (as shown in FIG. 1). In the tube assemblies 10 disclosed herein, the separator 16 does not include any clad layers. It is believed that without such clad layers, the manufacturing process is simplified in that lubricants used to form such clad layers no longer need to be removed after clad layer formation. It is believed that the layers 18 increase the strength of the separator 16, and the overall tube assembly 10.
Referring now to FIG. 2, an embodiment of a combo-cooler 100 is depicted. Generally, the combo-cooler 100 includes first and second end tanks 20, 20′, a first plurality 22 of tubes 12 having layer 18 thereon, and a second plurality 24 of tubes 14 having layer 18 thereon are fluidly attached to each of the ends tanks 20, 20′. In this non-limiting embodiment, the first plurality 22 of tubes 12 forms an oil cooler, and the second plurality 24 of tubes 14 forms the condenser. It is to be understood that other desirable coolers may also be formed in the combo-cooler 100.
The separator 16 (without clad layers) is positioned between each of the tubes 12, 14. As shown in FIG. 2, each of the end tanks 20, 20′ generally includes an inlet 26, an outlet 28 and baffles 30, 30′. One of the inlets 26 and one of the outlets 28 services the first plurality 22 of tubes 12, and another of the inlets 26 and outlets 28 services the second plurality 24 of tubes 14. Baffles 30 in each of the end tanks 20, 20′ separate the respective pluralities 22, 24 (and coolers) from each other. It is to be understood that additional baffles 30′ may be positioned within one or both end tanks 20, 20′ to direct the flow of fluid within a particular plurality 22,24 of tubes 12, 14.
The respective inlet 26 and outlets 28 are separated by the baffles 30. It is to be understood that all inlets 26, outlets 28 and baffles 30 may be included on one of the end tanks 20, 20′.
While a combo- or tri-cooler 100 is shown in FIG. 2, it is to be understood that the tube assembly 10 disclosed herein may be implemented into a single heat exchanger (not shown).
While several embodiments have been described in detail, it will be apparent to those skilled in the art that the disclosed embodiments may be modified. Therefore, the foregoing description is to be considered exemplary rather than limiting.

Claims

1. A tube assembly, comprising:

at least a first tube and a second tube;

a separator positioned between the first tube and the second tube; and

a layer established on at least a portion of each of the first and second tubes, the layer including silicon and a fluxing agent.

2. The tube assembly as defined in claim 1 wherein the separator does not include a clad layer thereon.

3. The tube assembly as defined in claim 1 wherein each of the layers further includes a binder.

4. The tube assembly as defined in claim 1 wherein the separator is formed of an aluminum alloy that is compatible with brazing.

5. The tube assembly as defined in claim 1 wherein the fluxing agent is configured for brazing aluminum components.

6. The tube assembly as defined in claim 1 wherein the silicon is in the form of a powder.

7. The tube assembly as defined in claim 1 wherein the fluxing agent contains zinc.

8. The tube assembly as defined in claim 1 wherein the first tube is one of a condenser tube and an oil cooler tube, and wherein the second tube is an other of the condenser tube and the oil cooler tube.

9. The tube assembly as defined in claim 1 wherein the first tube is different from the second tube.

10. A method for increasing strength of a tube assembly, the method comprising:

establishing a layer, including silicon and a fluxing agent, on at least a portion of an exterior surface of each of a first tube and a second tube; and

positioning a separator between the first tube having the layer thereon and the second tube having the layer thereon.

11. The method as defined in claim 10 wherein the method does not include establishing a clad layer on the separator.

12. The method as defined in claim 10 wherein prior to establishing the layer, the method further comprises forming a mixture including the silicon, the fluxing agent, and a binder; and wherein establishing the layer includes depositing the mixture on the exterior surface of each of the first tube and the second tube.

13. The method as defined in claim 12 wherein depositing is accomplished via a coating process, a roll coating process, or a spraying process.

14. The method as defined in claim 10 wherein the separator is formed of an aluminum alloy that is compatible with brazing.

15. The method as defined in claim 10 wherein the fluxing agent is configured for brazing aluminum components or contains zinc.

16. A combo-cooler, comprising:

first end tank;

a second end tank;

a first plurality of tubes in fluid communication with the first and second end tanks;

a second plurality of tubes in fluid communication with the first and second send tanks;

a layer established on at least a portion of each of the first and second plurality of tubes, each layer including silicon and a fluxing agent; and

a separator positioned between each of the tubes.

17. The combo-cooler as defined in claim 16 wherein the separator does not include a clad layer thereon.

18. The combo-cooler as defined in claim 16 wherein each of the layers further includes a binder.

19. The combo-cooler as defined in claim 16 wherein the separator is formed of an aluminum alloy that is compatible with brazing.

20. The combo-cooler as defined in claim 16 wherein the fluxing agent is configured for brazing aluminum components or contains zinc.

21. The combo-cooler as defined in claim 16 wherein the silicon is in the form of a powder.

22. The combo-cooler as defined in claim 16 wherein the first plurality of tubes is one of a condenser tube and an oil cooler tube, and wherein the second plurality of tubes is an other of the condenser tube and the oil cooler tube.

23. The combo-cooler as defined in claim 16 wherein the first plurality of tubes is different from the second plurality of tubes.