US20150068715A1

US20150068715A1 - Heat exchanger

Info

Publication number: US20150068715A1
Application number: US14/022,263
Authority: US
Inventors: Jon Raver
Original assignee: Ford Global Technologies LLC
Current assignee: Ford Global Technologies LLC
Priority date: 2013-09-10
Filing date: 2013-09-10
Publication date: 2015-03-12

Abstract

A method of manufacturing a heat exchanger and the heat exchanger made according to the method. The heat exchanger includes a pair of headers that define a plurality of slots. Each of the slots has a pair of nose ends that are disposed within the planar surface. Each of the slots have a first flange and second flange formed on opposite sides of the slots that extend between the pair of nose ends and are recessed into the header relative to the planar surface. One end of each of the tubes is assembled into one of the slots and is connected by a braze weld to the first flange, the second flange, and the nose ends.

Description

TECHNICAL FIELD

The present disclosure relates to heat exchangers, and in particular header plates of heat exchangers and related manufacturing methods.

BACKGROUND

Heat exchangers are used to remove heat from mechanical systems. For instance, radiators are used in automobiles to remove heat from the engines. Other types of heat exchangers include heater cores, condensers, evaporators and the like. A radiator consists of two opposing radiator tanks separated by a tube bundle and fins surrounding the tube bundle. As coolant is passed through an engine block, the coolant absorbs the heat from the engine. The hot coolant is then fed into a radiator tank and is circulated through the tube bundle. The heat from the coolant is transferred to the fins and transferred to ambient air. The coolant transfers heat as it travels to the opposite radiator tank, which is then fed back to the engine.
Each radiator tank may include a header plate that receives one end of the tubes in the tube bundle. The header plate defines openings for receiving the tubes. Header plates vary depending on how the tube receiving openings are created. One type of header plate type is a punched style header plate. The openings in a punched style header plate type are punched into the header plate with a punch that removes a slug from the header plate. The openings may have circular, oval or rectangular shapes. A problem with punched style header plates is that the tube walls have only limited contact with the punched edges of the header plates. This problem is magnified when the tubes are folded tubes. The folded tubes have a delta region that does not provide a surface that sits flush with the punched style header plate. This delta region can be difficult to seal with braze clad during the manufacturing process.
Another type of header plate type is a pierced style header plate. The openings in a pierced style header plate type are formed by piercing through the header plate to form an opening by cutting a slit in the material and forming the edges of slit apart. Unlike the punched style header plate, no slug is removed when piercing the header plate. A problem with pierce style header plates is that they have collars that may crack around the nose area. Cracked collars may be difficult to seal with braze clad during the manufacturing process.
The above problems and other problems are addressed by this disclosure as summarized below.

SUMMARY

One aspect of the present disclosure relates to a method of making a heat exchanger by punching a pair of spaced nose openings in a header and piercing a portion of the header between the nose openings. A first and a second flange are formed and are recessed into the header that extends between the pair of nose openings. A tube is attached to the header and brazed to the flanges.
Other aspects of the above method may also include cladding the header with a layer of brazing material before punching and piercing the header. The tube may be folded longitudinally to form a plurality of fluid channels in the tube. A delta region where the tube ends are folded may be filled with cladding material. The tube may be clad before folding the tube. The tube may be brazed to the second flange and the nose openings of the header.
Another aspect of the present disclosure relates to a method of making a heat exchanger that includes punching a pair of spaced nose openings in the header and piercing a portion of the header between the nose openings to form a first flange and a second flange that are recessed into the header and that extend between the pair of nose openings. The tube is cladded and folded to form a plurality of fluid channels in the tube. The tube is then assembled into the header and brazed to the header at the first flange, the second flange, and the nose openings of the header.
Yet another aspect of the present disclosure relates to a heat exchanger. The heat exchanger includes a plurality of tubes and a header having a planar surface and defining a plurality of slots. Each of the slots preferably has a pair of nose ends that lie within the planar surface. Each of the slots further has a first and a second flange formed on opposing sides of the slots that extend between the pair of nose ends. The slots are recessed into the header relative to the planar surface. One end of each of the tubes is assembled into one of the slots and is connected by a braze weld to the first flange, the second flange, and the ends.
The other aspects of the heat exchanger above include tubes that are folded longitudinally and a clad fill in a delta region where two sides of a tube are folded towards. The heat exchanger includes a layer of clad material covering the header, a first a second flange formed by piercing the header, or a pair of nose ends formed by punching nose ends through the header.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded perspective view of a heat exchanger showing the tanks and the header plates.

FIG. 2 is a flowchart of an exemplary method of making a heat exchanger.

FIG. 3 is a fragmentary perspective view of a header plate with spaced nose openings separated by bridge portions.

FIG. 4 is a fragmentary perspective view of a header plate with spaced nose openings and pierced bridge portions.

FIG. 5 is a fragmentary perspective view of an exemplary folded tube for use with the heat exchanger of the present disclosure.

FIG. 6 is a fragmentary perspective view of the header plate attached to a tube bundle.

FIG. 7 is a top plan view of a folded tube attached to one of the header plate slots of FIG. 6.

FIG. 8 is a cross-section view taken along the line 8-8 in FIG. 7.

FIG. 9 is a cross-section view taken along the line 9-9 in FIG. 7.

FIG. 10 is a cross-section view taken along the line 10-10 in FIG. 7.

DETAILED DESCRIPTION

The illustrated embodiments are disclosed with reference to the drawings. However, it is to be understood that the disclosed embodiments are intended to be merely examples that may be embodied in various and alternative forms. The figures are not necessarily to scale and some features may be exaggerated or minimized to show details of particular components. The specific structural and functional details disclosed are not to be interpreted as limiting, but as a representative basis for teaching one skilled in the art how to practice the disclosed concepts.
Referring to FIG. 1, a heat exchanger 20 is illustrated as a radiator. The present disclosure is not limited to vehicles and is applicable to many forms of heat exchangers, such as air conditioners, oil coolers, and intercoolers. The heat exchanger 20 includes a top tank 22 and a bottom tank 24 that are separated by tubes 26 and fins 28. The top tank 22 includes a top header plate 30. Tubes 26 attach to the top header plate 30. The top tank 22 includes a fill port 32 and an inlet 34 to be connected to a liquid cooled mechanical system, such as an engine. The other ends of the tubes 26 are attached to a bottom header plate 36 that forms a part of the bottom tank 24. A cooling medium, such as a coolant, water, or air, is preferably circulated through the liquid cooled mechanical system, the tanks, and the tubes to cool the mechanical system.
FIG. 2 shows an example of a method of making a header plate, such as the top header plate 30 or the bottom header plate 36. The method 38 begins by providing a header plate at step 40. The header plate 30, 36 is covered by cladding material, such as brazing compounds including aluminum, copper, zinc, nickel, and combinations thereof at step 41. At step 42, header plate slots are made by punching spaced nose openings through the header plate leaving a bridge of material between the spaced nose openings. The bridge of material is pierced to provide a full length slot that extends between the two nose openings at step 44. Steps 42 and 44 are preferably repeated until the desired number of header plate slots are formed at step 46.
The tubes 26 are folded longitudinally in step 50. The folded tubes are arranged with the fins 28 to facilitate heat transfer. Both ends of the folded tubes are attached to the header plates at step 52. The folded tubes 26 are brazed to the header plates in step 53 such as by heating a filler metal above melting point and applying the filler material between the tubes and the header plates by capillary action.
Referring to FIG. 3, the step of creating nose openings is shown in detail. A header plate 54 is provided that has a planar surface. A first nose opening 56 is formed on the header plate 54 by punching a D-shaped hole through the planar surface. A second nose opening 58 is formed on the header plate 54 by punching a second D-shaped hole through the planar surface. The first nose opening 56 and the second nose opening 58 are separated by a first bridge of the header plate material 60. Nose openings 62 and 64 are also formed and separated by bridge of header plate material 66. Nose openings 68 and 70 are further formed and separated by bridge of header plate material 72. The nose openings may also be shaped as a circle or an oval. The pairs of punched nose openings are formed in the header plate preferably in a single punching operation.
Referring to FIG. 4, the header plate 54 is pierced to form flanges from the bridge of header plate materials 60, 66, and 72. The planar surfaces of the header plate portions surrounding the punched openings are raised as a result of piercing. Bridge of header plate material 60 is pierced to form first flange 74 and second flange 76. Bridge of header plate material 66 is pierced to form third flange 78 and fourth flange 80. Bridge of header plate material 72 is pierced to form fifth flange 82 and sixth flange 84.
The illustrated portion of a header plate 54 has three header plate slots. The first header plate slot 86 includes the first nose opening 56, the second nose opening 58, and the pierced opening surrounded by first flange 74 and second flange 76. The second header plate slot 88 includes the nose openings 62 and 64 and the pierced opening defined by the third flange 78 and the fourth flange 80. The third header plate slot 90 includes the nose openings 68 and 70 and the pierced opening defined by the fifth flange 82 and the sixth flange 84. After the desired number of header plate slots is formed on the header plate, the header plate may be covered with one or more layers of clad materials. Header plate 54 includes a combination of punched and pierced header plate slots.
Referring to FIG. 5, a folded tube 92 is illustrated that is adapted for use with the heat exchanger of the present disclosure. The folded tube 92 may be made of a stamped sheet of metal having sides preferably folded towards its center 98 to create two symmetrical fluid flow paths or channels 94 and 96. In other embodiments, multiple folds may be made in the tubes to define multiple fluid flow paths. The folded tube 92 includes nose portions 93 and 95 on both sides of the folded tube 92. The nose portions 93 and 95 are separated by a belly portion 97 at the periphery of the folded tube 92 that is opposite the center 98 where the folded sides meet. The symmetrical fluid flow paths allow a fluid medium, such as liquid or air, to flow for efficient heat exchange. The folded tube 92 may alternatively be made as an extrusion having a longitudinal fold in the center. One or more layers of clad materials may be added to the folded tube 92 either before folding the tube or after folding the tube 92.
Referring to FIG. 6, several folded tubes 92 may be arranged in a pattern with several fins 28. The folded tubes 92 may alternatively have fins embedded with them. The previously described header plate 54 may then be assembled with the tubes 92 such that the ends of the tubes 92 are inserted into their respective slots 86, 88, or 90. As shown in FIG. 7, brazing material 100 is added between the surfaces of the header plate in contact with the folded tubes 92. The brazing material 100 fills a delta region 102 that is the area formed between the header plate and the crease at the center 98 of the folded tube 92. Referring to FIGS. 3, 4, and 7, the nose portions 93 and 95 occupy the punched nose openings 56 and 58 or 62 and 64 or 68 and 70. The belly portion 97 of the folded tube 92 is adjacent to the flange formed from piercing, such as flange 76, 80, or 84. The belly portion 97 directly contacts the braze material 100 that attaches the belly portion 97 to the flange 76, 80, or 84. The brazing material may be the same as the clad material in certain embodiments.
Referring to FIGS. 8-10, nose portions 93 and 95 of tube 92 occupy the punched nose openings formed from punching the header plate and are directly contacting the braze material 100 that attach the tube to the header plate. The center 98 of the tube 92 is in direct contact with the braze material 100 between the flange 76 and the tube 92. The delta region is filled with braze material 100 as previously shown in FIG. 7. The belly portion 97 directly contacts the braze material 100 that attaches the belly portion 97 to the flange 76 (FIG. 9). In FIG. 10, the center portion 98 and the belly portion 97 of the tube 92 are surrounded by and contact the braze material 100 that is sandwiched in between flange 76 and 74. Flange 76 and 74 may also be covered by braze material 100. In certain embodiments, the braze material and the clad material are made of a different materials. The tubes and the header plates may be covered by clad material where the braze materials and the clad materials are different. Braze material may be applied between the nose portions of the tubes and the nose openings and between the flanges and belly portion or the center portion of the tubes.
Punched style header plates that have header plate slots formed by punching holes on the header plates do not ensure direct contact between the tubes and either the header material or the clad material. The problem is magnified when the tubes being used are folded tubes. Tubes may detach from the header plates causing the heater exchange tanks including the header plate to leak. The folded tubes have a delta region that does not provide a surface that sits flush with the header plate. Pierced style header plates have been proposed to solve this problem. However, existing pierced style header plates that have header plate slots formed by piercing the header plates may have collars that crack, especially around the nose area. Cracked collars may be difficult to seal with braze clad during the manufacturing process.
The heat exchanger of the present disclosure includes header plates that ensure that the tubes have sufficient contact with the braze materials covering the header plates, regardless of whether the tubes are folded or not. The header plates have slots that are both punched and pierced. Thus, the header plates combine the beneficial aspects of punched and pierced header plates. The header plates have punched spaced nose openings and are less susceptible to cracking The nose openings are spaced apart by bridge material that is pierced so that the delta regions of the folded tubes can be filled with braze or clad materials when the tubes are attached to the header plate.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the disclosed apparatus and method. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the disclosure as claimed. The features of various implementing embodiments may be combined to form further embodiments of the disclosed concepts.

Claims

What is claimed is:

1. A method of making a heat exchanger comprising:

punching a pair of spaced nose openings in a header;

piercing a portion of the header between the nose openings to form a first flange and a second flange that are recessed into the header and that extend between the pair of nose openings;

attaching a tube to the header; and

brazing the tube to the first flange and the second flange.

2. The method of claim 1 further comprising:

cladding the header with a layer of brazing material before punching and piercing the header.

3. The method of claim 1 further comprising:

folding the tube longitudinally to form a plurality of fluid channels in the tube.

4. The method of claim 3 wherein the tube includes ends that are folded towards a delta region, and further comprising filling the delta region with brazing material.

5. The method of claim 3 further comprising cladding the tube before folding the tube.

6. The method of claim 1 further comprising brazing the tube to the second flange and the nose openings of the header.

7. A method of making a heat exchanger comprising:

cladding a header with a first layer of braze;

punching a pair of spaced nose openings in the header;

cladding a tube with a second layer of braze;

folding the tube to form a plurality of fluid channels in the tube;

assembling the tube into the header; and

brazing the tube to the first flange, the second flange, and the pair of nose openings on the header.

8. The method of claim 7, wherein the tube includes sides folded towards a delta region, the method further comprising filling the delta region with clad material.

9. The method of claim 8, further comprising brazing the clad material to the first flange.

10. The method of claim 8, wherein the tube includes a belly portion opposite the delta region and further comprising brazing the belly portion to the second flange.

11. A heat exchanger comprising:

a plurality of tubes; and

a header having a planar surface and defining a plurality of slots, wherein each of the slots include a pair of nose ends that are disposed within the planar surface, wherein each of the slots have a first flange and second flange formed on opposite sides of the slots that extend between the pair of nose ends and are recessed into the header relative to the planar surface, wherein one end of each of the tubes is assembled into one of the slots and is connected by a braze weld to the first flange, the second flange, and the nose ends.

12. The heat exchanger of claim 11, wherein the tubes are folded longitudinally.

13. The heat exchanger of claim 11, wherein the tubes have sides folded towards a delta region and further comprising a clad material in the delta region.

14. The heat exchanger of claim 11, further comprising a layer of clad material covering the header.