Two-piece header/manifold construction for a heat exchanger having flattened tubes

Abstract

A header/manifold construction (14) is adapted to receive a plurality of flattened tube ends (42) in a heat exchanger (10) having a plurality of flattened tubes (12). The header/manifold construction (14) includes first and second pieces (20, 22) extending along a longitudinal axis (24). The first piece (20) has a C-shaped transverse cross defined by an elongate opening (44) extending along the longitudinal axis (24), with a plurality of tube slots (40) spaced along the axis (24) opposite from the opening (44). The second piece (22) has a T-shaped transverse cross section with two side legs (48, 50) extending from opposite sides of a center leg (46), with the legs (46, 48, 50) being bonded to surfaces of the first piece (20).

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

Not Applicable.

FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not Applicable.

MICROFICHE/COPYRIGHT REFERENCE

Not Applicable.

FIELD OF THE INVENTION

This invention relates to heat exchangers and more particularly to header/manifold constructions for heat exchangers having a core formed from flattened tubes, and in more particular applications such heat exchangers that are used in high pressure systems, such as CO₂ refrigeration or air conditioning systems.

BACKGROUND OF THE INVENTION

There are many ways to design a heat exchanger such as a gas cooler or condenser for air conditioning systems for automotive or vehicular applications. The counter flow configuration or CF design relies on flowing refrigerant through multiple rows of tubes in a counterflow direction to the air flow passing through the core of the heat exchanger. Accordingly, the CF design requires tubes to be bent in a special manor or to use multiple header/manifolds to redirect the refrigerant flow through the multiple rows of tubes. These multiple header/manifolds and/or tube bends can add cost to the heat exchanger. Another alternative is the parallel flow configuration or PF design which typically has one row or slab of flattened microchannel extruded tubes extending between two header/manifolds. To enhance heat transfer, the refrigerant may be directed through multiple passes by using baffles in the header/manifolds.

While PF designs such as described above are often used for condensers in conventional R134a refrigerant systems, it is challenging to design a header/manifold to accommodate wide microchannel extruded tubes while withstanding the high operating pressures required for CO₂ or other transcritical refrigerant systems.

SUMMARY OF THE INVENTION

In accordance with one feature of the invention, a header/manifold construction is provided and is adapted to receive a plurality of flattened tube ends in a heat exchanger having a plurality of flattened tubes. The header/manifold construction includes first and second pieces extending along a longitudinal axis.

As one feature, the first piece has a transverse cross section defined by a tube receiving wall, a side wall spaced opposite from the tube receiving wall, and two nose walls that are spaced opposite from each other to connect the tube receiving wall and the side wall. The tube receiving wall has a plurality of tube slots spaced along the longitudinal axis to receive the tube ends, and the side wall is divided by an elongate opening extending along the longitudinal axis. The second piece has a transverse cross section defined by a center leg and a two side legs extending from opposite sides of the center leg. The center leg extends through the opening in the side wall and has an end surface bonded to an interior surface of the tube receiving wall, with the end surface being interrupted by a plurality of tube end clearance notches, each of the notches aligned with a corresponding one of the tube slots in the tube receiving wall. The two side legs are bonded to an exterior surface of the side wall on opposite sides of the opening.

In one feature, the first piece has a C-shaped transverse cross defined by an elongate opening extending along the longitudinal axis. The first piece has a plurality of tube slots spaced along the longitudinal axis opposite from the opening. The second piece has a T-shaped transverse cross section with two side legs extending from opposite sides of a center leg. The center leg extends through the elongate opening and has an end surface bonded to an interior surface of the first piece, with the end surface interrupted by a plurality of tube end clearance notches and each of the notches aligned with a corresponding one of the tube slots in the tube receiving wall. The two side legs are bonded to an exterior surface of the first piece on opposite sides of the opening.

According to one feature, the second piece has a mount flange extending away from the exterior surface of the side wall. As one further feature, the mount flange has an elongate slot extending along the longitudinal axis. As another further feature, the mount flange has a transverse opening extending therethrough.

In accordance with one feature, each of the tube end clearance notches is sized to provide a fluid flow gap between the center leg and a tube end received the corresponding one of the tube slots.

As one feature, the end surface of the center leg is further interrupted by a plurality of tabs, with each of the tabs extending through a tab receiving opening in the tube receiving wall and being deformed to engage the second piece with the first piece.

In one feature, the second piece is an extrusion.

According to one feature, at least one of the first and second pieces is braze clad.

In accordance with one feature, the first piece is braze clad.

In one feature, the first piece is a formed piece of braze clad sheet metal.

As one feature, the center leg is bonded to opposite side edges of the opening in the side wall.

According to one feature, the side legs are normal to the center leg.

In accordance with one feature, there is a port formed in the second piece, and the header/manifold construction further includes a fluid connection bonded in the port.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a partially broken, sectioned, perspective view of a heat exchanger including a header/manifold construction embodying the present invention;

FIG. 2 is an enlarged, partial section view taken from line 2-2 in FIG. 1;

FIG. 3 is a partial section view taken from line 3-3 in FIG. 2; and

FIGS. 4-8 are partial perspective views showing alternate forms for header/manifold constructions embodying the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

With reference to FIGS. 1 and 2, a PF type heat exchanger is shown in the form of a gas cooler 10 for use in a CO₂ refrigeration system. The heat exchanger 10 includes a plurality of flattened, microchannel extruded tubes 12 extending parallel to each other between a pair of header/manifolds 14 (only one shown), with fins 16 extending between the tubes and a fluid connection 18 extending from the header/manifold 14. While the fins 16 are shown as plate fins, it should be understood that other types of fins such as serpentine or corrugated fins may be desirable in many applications. Similarly, while microchannel extruded tubes 12 are shown, other forms of flattened tubes may be desirable in some applications. Preferably, all of the components of the heat exchanger 10 are formed from a suitable material, such as aluminum, steel, or copper, and are bonded together such as by brazing, and preferably in a single braze operation.

The header/manifold 14 is a multi-piece construction formed from two elongate pieces 20 and 22 that extend along a longitudinal axis 24, with an pair of end baffles 26 (only one shown in FIG. 1) provided to enclose a manifold space 28 within the header/manifold 14. Although not shown, it may be desirable in some applications to include additional baffles within the manifold space 28 to subdivide the space 28 into a plurality of flow manifolds for the multi-passing of the refrigerant through the banks of the tubes 12, as is known.

As best seen in FIG. 2, the piece 20 has a C-shaped transverse cross section defined by a tube receiving wall 30, a side wall 32 spaced opposite from the tube receiving wall 30, and two nose walls 34 that are spaced opposite from each other to connect the tube receiving wall 30 and the side wall 32. As best seen in FIGS. 1 and 3, the tube receiving wall 30 has a plurality of tube slots 40 spaced along the longitudinal axis 24 to receive ends 42 of the tubes 12. As best seen in FIGS. 1 and 2, the side wall 32 is divided in half by an elongate gap or opening 44 extending along the longitudinal axis over the entire length of the piece 20.

Preferably, the piece 20 is formed from a metal sheet, and in a highly preferred form from a piece of braze clad sheet metal, such as braze clad aluminum. In this regard, it is preferred that the tube slots 40 be pierced or punched while the sheet is flat. However, in some applications it may be desirable to pierce or punch the tube slots 40 after the sheet has been formed into the C-shape. While a sheet is preferred, it should be understood that it is possible to form the piece 20 in other ways, such as by extrusion or by molding.

As best seen in FIG. 1, the piece 22 has a T-shaped transverse cross section defined by a center leg 46 and a two side legs 48 and 50 extending from opposite sides of the center leg 46. The two side legs 48 and 50 are bonded (such as by brazing) to an exterior surface 52 of the side wall 32 on opposite sides of the opening 44. The center leg 46 extends through the opening 44 in the side wall 32 and has an end surface 54 bonded (such as by brazing) to an interior surface 56 of the tube receiving wall 32.

As best seen in FIG. 1, the end surface 54 is interrupted by a plurality of tube end clearance notches 58, with each of the notches 58 aligned with a corresponding one of the tube slots 40 in the tube receiving wall 30. Preferably, each of the notches 58 is sized to, provide a fluid flow gap 60 between the center leg 46 and the tube end 42 received in the corresponding tube slot 40 to allow the refrigerant to freely flow between both sides of the center leg 46. Preferably, the gap 60 extends around the top and sides of the tube end 42.

As best seen in FIG. 3, As another optional, but preferred feature, the end surface 54 is further interrupted by a plurality of tabs 62, with each of the tabs 62 extending through a tab receiving opening 64 in the tube receiving wall 30 and being deformed, such as by bending, or staking or swaging with a chisel-like tool, to engage the tab 62 to the wall 30 and thereby the pieces 20 and 22 together for a bonding operation, such as brazing. This is desirable because it can eliminate the need for a fixture or other means to hold the pieces 20 and 22 together so that a suitable bond joints are formed between all of the mating surfaces during brazing. While a tab 62 and corresponding opening 64 are shown between each of the tube slots 40, it should be understood that in some applications may be desirable to have fewer tabs 62 and openings 64 so that they are not provided between every tube slot 40.

The center leg 46 may also include a baffle slot 66 for receiving the end baffle 26 and holding the baffle 26 in its desired location during the brazing operation.

Preferably, the piece 22 is an extrusion, with the notches 58 and tabs 62 (if provided) being formed by a suitable technique, such as machining or die cutting, after the T-shaped cross section is extruded. However, it should be understood that in some applications it may be desirable to form the piece 22 using another suitable technique, such as by machining from a piece of bar stock or by molding.

Preferably, the piece 20 is clad with a suitable braze material, and the pieces 20, 22, and 26 of the header/manifold 14 and the tube ends 42 are brazed together in a single oven braze operation at the same time as the other components of the heat exchanger 10 are brazed together. In this regard, it is preferred that the clearance between mating parts, such as, for example, the tube slots 40 and the tube ends 42, and the tabs 62 and the openings 64, be designed such that a suitable sealed braze joint is formed between the mating parts. Further in this regard, it is preferred that the clearance between the opening 44 and the center leg 46 be such that a braze joint be formed between the center leg 46 and opposite side edges 70 of the opening 44. However, in some applications this may not be desired and/or required. While braze cladding is preferred on the piece 20, it should be understood that in some applications the braze material may be applied to the components of the header/manifold 14 in other suitable forms, such as by cladding some of the other components or by applying the braze material to the components after assembly.

FIG. 1 shows an option wherein an opening 72 has been formed in the pieces 20 and 22 to receive the fluid connection or cylindrical tube 18, which in the illustrated embodiment includes a fluid connection mount block 74. It can be seen in FIG. 1 that the diameter of the fluid connection 18 is such that fluid flow paths 76 (only one shown) are provided on either side of the center leg 46. As with the other mating parts, it is preferred that the clearances between the opening 72 and the fluid connection 18 be such that a suitable sealed bond joint is formed.

FIGS. 4 and 5 show two possible alternatives wherein the piece 22 includes a mount flange 80 extending away from the exterior surface 52 opposite from the center leg 46. The mount flange 80 may extend along the axis 24 over the entire length of the piece 22, or may extend over only one or more selected portions of the length. FIG. 4 shows an option wherein the flange 80 is of sufficient width to accommodate an elongate mount slot 82 in the flange 80 extending along the axis 24. FIG. 5 shows an option wherein a transverse opening 84 is provided in the flange 80 for receiving a mount bracket, bolt, or stud, rivet or other type of fastener. While two options are shown, it should be appreciated that the flange 80 can be modified in other ways to accommodate other mounting structures.

FIG. 6 shows yet another embodiment wherein the outer ends/edges 84 and 86, respectively, of the legs 48 and 50 have been modified so that the exposed portion of the piece 22 acts as the male part of a dovetail type connection with a dovetail slot 90 of a mating component or mount piece 92 that can be slid onto the exposed portion of the piece 22 in the axial direction to engage the male dovetail with the female dovetail slot 92.

FIG. 7 shows an alternate embodiment wherein a dovetail slot 94 is formed in the legs 48 and 50 to mate with the male dovetail that would be provided on a mating component, such as a mount piece. In this embodiment, the dovetail rails can be deformed to lock the mating component in its proper location.

FIG. 8 shows a further alternative wherein a pair of flanges or feet 96 and 98, respectively, have been provided on the legs 48 and 50 to define a mount receiving groove 100 that can receive a mating flange of a mount component, with the flanges 96 and 98 being deformed to lock the part in the proper location.

It should be appreciated that the mating shapes of the two pieces can allow for a cost effective construction of the header/manifold 14, with the bonding of the legs 46 and 48 to the surfaces 56 and 52, respectively, allowing for the structure of the piece 22 to support the structure of the piece 34, and particularly the walls 30 and 32, so that the header/manifold can withstand the high pressure associated with CO₂ and other transcritical refrigeration systems.

Claims

1. A header/manifold construction adapted to receive a plurality of flattened tube ends in a heat exchanger having a plurality of flattened tubes; the header/manifold construction comprising:

a first piece extending along a longitudinal axis and having a transverse cross section defined by a tube receiving wall, a side wall spaced opposite from the tube receiving wall, and two nose walls that are spaced opposite from each other to connect the tube receiving wall and the side wall, the tube receiving wall having a plurality of tube slots spaced along the longitudinal axis to receive the tube ends, the side wall being divided by an elongate opening extending along the longitudinal axis; and

a second piece extending along the longitudinal axis, the second piece having a transverse cross section defined by a center leg and a two side legs extending from opposite sides of the center leg; the center leg extending through the opening in the side wall and having an end surface bonded to an interior surface of the tube receiving wall, the end surface interrupted by a plurality of tube end clearance notches, each of the notches aligned with a corresponding one of the tube slots in the tube receiving wall, the two side legs bonded to an exterior surface of the side wall on opposite sides of the opening.

2. The header/manifold construction of claim 1 wherein the second piece has a mount flange extending away from the exterior surface of the side wall.

3. The header/manifold construction of claim 2 wherein the mount flange has an elongate slot extending along the longitudinal axis.

4. The header/manifold construction of claim 2 wherein the mount flange has a transverse opening extending therethrough.

5. The header/manifold construction of claim 1 wherein each of the tube end clearance notches is sized to provide a fluid flow gap between the center leg and a tube end received in the corresponding one of the tube slots.

6. The header/manifold construction of claim 1 wherein the end surface of the center leg is further interrupted by a plurality of tabs, each of the tabs extending through a tab receiving opening in the tube receiving wall, each of the tabs being deformed to engage the second piece with the first piece.

7. The header/manifold construction of claim 1 wherein the second piece is an extrusion.

8. The header/manifold construction of claim 1 wherein at least one of the first and second pieces is braze clad.

9. The header/manifold construction of claim 1 wherein the first piece is braze clad.

10. The header/manifold construction of claim 1 wherein the first piece is a formed piece of braze clad sheet metal.

11. The header/manifold construction of claim 1 wherein the center leg is bonded to opposite side edges of the opening in the side wall.

12. The header/manifold construction of claim 1 wherein the side legs are normal to the center leg.

13. The header/manifold construction of claim 1 wherein there is a port formed in the second piece, and further comprising a fluid connection bonded in said port.

14. The header/manifold construction of claim 1 wherein the side legs are configured to define a dovetail rail.

15. The header/manifold construction of claim 1 wherein the side legs are configured to define a dovetail slot.

16. The header/manifold construction of claim 1 wherein the side legs include a pair of flanges defining a longitudinal channel.

17. A header/manifold construction adapted to receive a plurality of flattened tube ends in a heat exchanger having a plurality of flattened tubes; the header/manifold construction comprising:

a first piece extending along a longitudinal axis and having a C-shaped transverse cross defined by an elongate opening extending along the longitudinal axis, the first piece having a plurality of tube slots space spaced along the longitudinal axis opposite from the opening;

a second piece extending along the longitudinal axis, the second piece having a T-shaped transverse cross section with two side legs extending from opposite sides of a center leg, the center leg extending through the elongate opening and having an end surface bonded to an interior surface of the first piece, the end surface interrupted by a plurality of tube end clearance notches, each of the notches aligned with a corresponding one of the tube slots in the tube receiving wall, the two side legs bonded to an exterior surface of the first piece on opposite sides of the opening.

18. The header/manifold construction of claim 17 wherein the second piece has a mount flange extending away from the exterior surface of the side wall.

19. The header/manifold construction of claim 18 wherein the mount flange has an elongate slot extending along the longitudinal axis.

20. The header/manifold construction of claim 18 wherein the mount flange has a transverse opening extending therethrough.

21. The header/manifold construction of claim 17 wherein each of the tube end clearance notches is sized to provide a fluid flow gap between the center leg and a tube end received in the corresponding one of the tube slots.

22. The header/manifold construction of claim 17 wherein the end surface of the center leg is further interrupted by a plurality of tabs, each of the tabs extending through a tab receiving opening in the tube receiving wall, each of the tabs being deformed to engage the second piece with the first piece.

23. The header/manifold construction of claim 17 wherein the second piece is an extrusion.

24. The header/manifold construction of claim 17 wherein at least one of the first and second pieces is braze clad.

25. The header/manifold construction of claim 17 wherein the first piece is braze clad.

26. The header/manifold construction of claim 17 wherein the first piece is a formed piece of braze clad sheet metal.

27. The header/manifold construction of claim 17 wherein the center leg is bonded to opposite side edges of the opening in the side wall.

28. The header/manifold construction of claim 17 wherein the side legs are normal to the center leg.

29. The header/manifold construction of claim 17 wherein there is a port formed in the second piece, and further comprising a fluid connection bonded in said port.

30. The header/manifold construction of claim 17 wherein the side legs are configured to define a dovetail rail.

31. The header/manifold construction of claim 17 wherein the side legs are configured to define a dovetail slot.

32. The header/manifold construction of claim 17 wherein the side legs include a pair of flanges defining a longitudinal channel.