Multiple-channel conduit with separate wall elements

Abstract

A multiple channel tube and method of making such a tube. The preferred method includes providing a plurality of wall elements that are elongated in a longitudinal direction and that that have an elongated cross-section transversely to the longitudinal direction. The wall elements have opposite lateral sides disposed on opposite ends of an elongate axis of the cross-section. The wall elements are placed between first and second sheet members, and the opposite lateral sides of the wall elements are adhered to the sheet members to provide a plurality of channels defined between the adhered wall elements and the sheet members.

Description

FIELD OF THE INVENTION

The present invention relates to a multiple-channel conduit and a method of making such a conduit, such as a heat exchanger tube. More particularly, the present invention relates to a heat exchanger in which wall elements are adhered to a sheet to define channels.

BACKGROUND OF THE INVENTION

Heat exchanger tubes have traditionally been constructed by soldering or brazing crests of an undulating spacer sheet within a flattened tube, as described, for instance in U.S. Pat. No. 4,998,580. Discrete, hydraulic flow-paths are thus provided between the undulations of the spacer. This structure improves the heat conduction between the outside of the flattened tube and the fluid flowing therethrough.

U.S. Pat. No. 4,360,958 teaches another method of making a heat exchanger, in which a plurality of passageways are provided by inserting wires into a flattened tubular member. The wires are spaced and disposed in parallel from each other and have surfaces with a lower melting point than the tubular member. The surfaces of the wires are then heated to above their melting point to secure them to the tube.

Another teaching that uses wires is U.S. Pat. No. 2,396,522, in which square cross section rods or circular cross-section wires that are welded to walls. Depending on the materials used, the parts can be soldered or welded together. The side edges of the assemblies taught have angular features.

A new heat exchanger construction is needed that can simplify construction and reduce required material, and preferably allow use of high internal pressure. The present invention now provides a solution to this need.

SUMMARY OF THE INVENTION

The present invention is directed to a new multiple-channel conduit, such as a tube for use in heat exchange applications, and to a method of producing such a conduit. In the preferred embodiment, a plurality of wall elements are provided. The wall elements are preferably elongated in a longitudinal direction and have an elongated cross-section oriented transversely to the longitudinal direction. The wall elements also have opposite lateral sides that are disposed on opposite ends of an elongate axis of the cross-section. The wall elements are placed between first and second sheet members, and opposite sides of the wall elements are adhered to the sheet members to define a plurality of channels between the adhered wall elements and sheet members.

Preferably, the wall elements are adhered to the sheet members by melting a material, such as by melting the wall element or sheet material in a welding process, or by melting a separate material, such as in a brazing or soldering process. Most preferably, the opposite lateral sides of the wall elements are welded to the sheet members by applying an electrical current therebetween in an amount sufficient to melt a portion of the material of each sheet member. The preferred type of welding to be used is electrical-resistance welding.

The wall elements are preferably made by compressing and flattening one or more wires, such as by roll forming. A welding projection can be provided extending laterally at the opposite lateral sides of the wall elements in a configuration to promote welding to the sheet members.

The sheet members themselves can be part of the single sheet or can alternatively be made from separate sheets. This sheet can be bent around an interior space within which the wall elements are adhered to the sheet members. The lateral ends of the sheet are preferably adhered to each other such as by welding to enclose and define at least one of the channels in cooperation with at least one of the wall elements. The bent and adhered sheets preferably forms an exterior flattened tube.

The wall elements preferably have a lateral width measured between their lateral sides of less than about 10 mm, more preferably less than about 5 mm, and most preferably less than about 2 mm. At least one of the sheet members and/or wall elements has a thickness of less than about 0.5 mm. The wall elements and sheet members can be made of any suitable material, and a preferred material is copper, a copper alloy or steel.

The preferred tube is formed to provide a heat exchanger tube. In the preferred heat exchanger tube, the plurality of wall elements are preferably of separate construction from each other, but are connected by the sheet that surrounds the wall elements and to which they are adhered. Welds, or alternatively brazing or soldering joints, preferably adhere the wall elements to the sheet. In one embodiment, the tube extends along a serpentine pattern.

The invention thus provides an improved structure and the method of manufacturing for a multiple-channel tube, the production of which can be easily scalable and not prone to wasting significant amounts of material.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective cross-sectional view of a wire used to form a wall element of a preferred embodiment of the invention;

FIG. 2 is a perspective cross-sectional view of the wire formed as a wall element;

FIG. 3 is a cross-sectional view of a lateral end of a wall element in contact with a sheet member for adhesion thereto;

FIG. 4 is a perspective cross-sectional view of a heat exchanger tube constructed according to the preferred embodiment of the invention;

FIG. 5 is a perspective cross-sectional view showing wall elements being adhered to a sheet in the production of a heat exchanger tube;

FIG. 6 is a perspective cutaway view of a plurality of heat exchanger tubes associated with a header;

FIG. 7 is a front view of a heat exchanger that includes a plurality of headers and associated heat exchanger tubes;

FIG. 8 is a side cross-sectional view of another embodiment of a heat exchanger;

FIGS. 9-11 are end views of alternative embodiments of tubes constructed according to the invention;

FIG. 12 is a cross-sectional view of a lateral end of an alternative embodiment of a wall element with a sheet member for adhesion thereto; and

FIG. 13 is a front view of an embodiment of a heat exchanger with a serpentine tube.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a plurality of wires 10 are preferably flattened, such as by rolling or other compression process, to form wall elements 12, as shown in FIG. 2. The wall elements 12 are preferably elongated in a longitudinal direction 14, typically corresponding to the axial direction of the wire 10. Additionally, the wall elements 12 preferably have a cross-section that is elongated transversely with respect to the longitudinal direction, in a lateral direction 16, with opposite lateral sides 18 disposed on opposite ends of an elongate lateral axis of the cross-section. The cross-section is preferably the cross-section of the entire wall element 12, but can alternatively be of a wall portion thereof that extends substantially between sheet portions that define a tube. The wall elements 12 are preferably of separate construction and can be positioned independently in a tube to be produced.

The wall elements 12 are preferably further prepared for a subsequent welding process. As shown in FIG. 3, the lateral sides 18 of the wall elements 12 are formed with a welding projection, which can include a nub 20 that runs longitudinally and projects laterally. The nub 20 is configured promote welding of the lateral wall element sides 18. Projection welding techniques, as known in the art can be employed at the lateral sides, which improve the quality of electrical-resistance welded joints in high-conductivity alloys because they concentrate the welding current where desired.

In the preferred embodiment, the wall elements 12 are adhered to an outer sheet 22 that surrounds the wall elements 12 to form an exterior tube 24, as shown in FIG. 4, which preferably has a flattened, oval profile. The adhered wall elements 12 divide the interior of the exterior tube 24 into a plurality of channels 26 through which a liquid can be flowed in an assembled heat exchanger.

The sheet defines two sheet portions or members 28,30. Preferably sheet member 28 is joined with one set of lateral sides 18 of the wall element, and sheet member 30 is joined with the set of lateral sides 18 on the opposite lateral side. Although the sheet members 28,30 are part of a unitary single sheet in the preferred embodiment, in an alternative embodiment, the exterior tube can be formed from one or more sheets that are joined together. In one embodiment, the first and second sheet members are joined together from separate sheet stock.

The wall elements 12 are preferably adhered to the sheet 22 by welding, although other processes can alternatively be employed, such as brazing or soldering. Preferably, electrical-resistance welding is used. The wall elements 12 can be welded to the sheet 22 sequentially or simultaneously.

Additionally, the wall elements 12 can first be welded to one of the sheet members 28 when the sheet 22 is in an open configuration shown in FIG. 5. The sheet 22 can then be folded around the adhered wall elements 12, and the wall elements 12 can be welded the other sheet member 30 in a subsequent operation. Most preferably, however, the wall elements 12 are adhered to both opposing sheet members 28,30 in a single operation, such as by using electrode rollers in opposite sides of the oval exterior tube 24.

The free edges 32 of the sheet members 28,30 are preferably sealed to each other, such as by welding, preferably electrical-resistance welding or high-frequency welding, or by another suitable process, such as brazing or soldering. The weld can be a high frequency weld to form a seal between the welded members. If the free edges 22 are to be welded, one or both of these can be formed with welding protrusions, for example with a configuration similar to the protrusions 20 shown in FIG. 3. In the assembled heat-exchanger tube 44 shown in FIG. 4, welds 34 are present between the wall members 12 and the sheet 22 and between the welded sheet edges 32, with the wall elements 12 forming walls dividing the channels 26 in the interior space of the tube 24. One of the channels 26 is sealed by the weld 34 between the sheet members 28,30. In an alternative embodiment, the free ends 32 can be disposed in another location along the exterior tube, including extending through one of the sheet members 28,30 or on one of the flat sides of the exterior tube.

While other methods of adhering the wall elements 12 to the sheet 22 can be used, the preferred methods involve melting a material to effect the joining or fusing. While welding is preferred, most preferably the welding is accomplished by applying an electrical current between the portions to be welded. The preferred welds are seam welds, which can be made with wheel or roller electrodes, as known in the art. The seam welds 34 that are produced preferably seal the channels 26 from each other and from the exterior of the tube 24. Overlapping weld locations can be produced to provide a substantially continuous weld line.

The wall elements 12 and sheet 22 can be formed of the same material. In a preferred embodiment, a thin, high strength, brass material is used for the sheet 22, such as SM2385, and copper or a copper alloy is used for the wall elements 12, such as C12200. Aluminum, steel, their alloys, and other metals are other suitable materials. While materials with good heat conductivity are preferably used, in certain embodiments, such as in which heat exchanging properties are not critical, other materials can be employed, including plastics. Different welding and adhesion methods can be used to adhere plastic parts.

The preferred lateral width 36 of the adhered wall elements 12 is less than about 10 mm, more preferably less than about 5 mm, and most preferably less than about 2 mm or 1.5 mm. A preferred embodiment has a lateral width 36 of around 1 mm. Preferably, the lateral width 36 is at least about 0.3 mm, and more preferably at least about 0.4 or 0.6 mm. The thicknesses 38 of the sheet 22 and the wall elements 12 are preferably less than about 0.5 mm, more preferably less than about 0.3 mm, and most preferably less than about 2 mm. A typical thickness 38 is around 0.15 mm, and is preferably at least about 0.05 mm, and more preferably at least about 0.1 mm.

The inventive heat exchanger tubes are preferably assembled in a radiator or other heat exchanger, such as in a refrigerant condenser or evaporator, oil cooler, a charge-air cooler or other heat exchange device. The tubes can be used in cooling or heating applications, in which heat is conducted into or out from the cooling fluid that flows through the channels 26.

The number and locations of the wall elements 12 in the tube 24 can be varied and selected to provide channels 26 of different or the same sizes as each other. The lateral widths 36 of the wall elements 12 can also be varied as well. While the preferred embodiment has an elongated cross-section tube 24 with substantially flat side walls 42, other shapes can be obtained. Similarly, while the wall elements 12 are preferably substantially straight and have generally smooth and relatively flat surfaces, other curved configurations can also be used. The spacing between the wall numbers 12 can be decreased to withstand higher internal pressures, or increased to reduce production cost when atmospheric or low internal pressures are used in the assembled heat exchanger.

The invention thus provides a low cost manufacturing process that can be scalable, such as by increasing or reducing the number of wall elements 12. In particular, if high speed welding is used to join the wall elements and sheet members, substantially no additional or wasted material is needed or produced to manufacture the tubes in the preferred embodiment. To facilitate attaching and sealing, such as by brazing, soldering, or welding, in the subsequent assembly of an inventive heat exchanger tube in a radiator or other heat exchanger structure, as shown in FIG. 6, a smooth exterior surface can be provided on the outside of the assembled heat-exchanger tube, preferably without sharp bends.

In the embodiment of FIG. 6, a plurality of tubes 44 are brazed to a round tube header 46. The tubes 44 are inserted into elongated slots 48 in the curved sidewall of the header 46 and brazed or otherwise adhered thereto. The exterior surface of the tubes 44 are thus preferably substantially smooth, preferably rounded, and preferably also substantially free of small concavities, nooks, or other features that would hinder extensive sealing around the exterior thereof where the tubes 4 meet the header 46. Thus, any seams, such as between the ends 32 of the sheet members 28,30, are substantially smooth, so as to reduce or eliminate gaps in the seal between the tubes 44 and the header 46. These seals 50 and the wall elements 12 that are fixed to the sheet members 28,30 better allow the flow of refrigerant under pressure if desired. The seals 50 thus preferably can withstand elevated internal pressures as used in pressure flow heat exchangers, and the wall elements 12 preferably resist or prevent outward bowing of the sheet members 28,30 due to the pressurized refrigerant flowing through the tubes 44. Preferably, the tubes 44 can withstand at least about 500 psi, and more preferably at least about 600 psi. A preferred embodiment uses coolant at about 650 psi. By placing the wall elements 12 closer together, for instance, an embodiment can withstand internal coolant pressures of above about 1500 psi or 2000 psi.

Although the header 46 shown is generally cylindrical, other shapes can also be employed, such as headers with a D-shaped cross-section. Additionally, serpentine fins 48 can be joined to the tubes 44, and are preferably joined with pairs of adjacent tubes 44, in thermal conducing association therewith to improve heat exchange with the medium flowing over the exterior of the heat exchanger.

FIG. 7 shows an assembled heat exchanger 52 with a plurality of tubes 44 affixed in fluid association with headers 46 to provide a four-pass flat-tube condenser or evaporator. The fins 48 can be placed near the longitudinal ends of the tubes 44 or substantially along the tubes 44 entire longitudinal length. An extra set of fins 48 can be associated with the tubes 44 at the lateral sides of the heat exchanger and can be additionally supported by members, such as support tubes or plates 100 which can be provided without a fluid so much as to the header 46 or other prism carrying the refrigerant. The headers are divided internally by walls 54 to direct the refrigerant flowing therethrough in a plurality of passes, such as the four passes provided in the embodiment shown. Sequentially, a first pass is made between the headers 46 through tubes 56, a second pass is made through tubes 58, a third pass is made through tubes 60, and a fourth pass is made through tubes 62. The refrigerant is fed into header 46 before the first pass through inlet tube 64, and the refrigerant is outlet from the header 46 after the fourth pass through outlet tube 66. The inlet and outlet tubes are also adhered to the header 46, preferably be welding, and alternatively be brazing or soldering or another suitable method.

As shown in FIG. 8, an alternative embodiment of a header 68 is D-shaped, and formed of a curved portion 70 and is fixed and sealed by a suitable method of adhesion, including welding, brazing, and soldering, to a U-shaped member 72. The tubes 44 have two wall elements 12 with a longitudinal length 74 that is shorter than the longitudinal length 76 of the sheet members, preferably with longitudinal portions 78 at the longitudinal ends of the tubes 44 free of the wall elements 12.

FIGS. 9-11 show alternative constructions of the inventive tubes. The tube 80 of FIG. 9 has wall elements 12 positioned at the front and back ends of the tube 80. These wall elements 12 thus can be exposed at the front and back sides, and preferably seal the outer channels 82. Sheet members 84 are substantially flat. Tube 86 of FIG. 10 has sheet members 88 of separate construction that are welded or otherwise adhered and sealed at both front and back sides, at which the opposing sheet members 88 are preferably curved to form the outermost channels 90. The embodiment 92 of FIG. 11 has one flat sheet member 94 that is welded or otherwise adhered and sealed to a sheet member 96 with lateral sheet ends, which will become the front and back sides of the tube, that are curved to join the flat sheet member 94.

The preferred elongated cross-section of the wall elements, generally taken obliquely to the longitudinal direction, has an aspect ratio of at least about 1.2 of lateral length, in direction 16 corresponding to the front to back axis of the assembled tube, to shorter width, in direction 98 corresponding to the front to back axis of the assembled tube, as shown in FIG. 2. More preferably, the aspect ratio is at least about 1.5, and most preferably at least about 1.75. Certain embodiments can have a much higher aspect ratio, such as shown in FIG. 4, of above about 5 or more.

The aspect ratio of the tube cross-section itself is preferably greater than about 2, more preferably greater than about 5, and most preferably greater than about 10, and preferably less than about 30, and more preferably than about 20. The cross-section and the tube major and minor diameters are preferably measured on the outside of the tube 44.

Referring to FIG. 13, an embodiment of a heat exchanger 102 includes a tube 44 that is bent in a serpentine manner, with bends 104 and preferably straight portions 108. Fins 106 are in thermal conductive association with the serpentine portions of the tube 44. The serpentine portions 108 and 104 can be made from a single tube 44, or a series of tubes. The radius 110 of the bends 104 is preferably less than about 3 times the size of the tube cross-section that is parallel to the radius, which is preferably the small cross-sectional diameter of the tube 44, measured along the minor axis of the tube cross-section. In one embodiment, the bend 104 has a radius that is about 2.8 times the cross-sectional diameter parallel therewith, which is preferably the minor or major diameter of the cross-section. Another embodiment has a radius that is up to about 4 times and more preferably up to about five of 10 times the cross-sectional width parallel to the radius. In one embodiment, the fin height or tube pitch 112 between the preferably generally parallel tube portions 108 is between about 8 and 9 mm; the tube cross-section small diameter is between about 1 mm and 2 mm, and more preferably about 1.3 mm; the tube cross-section large diameter is between about 10 mm and 20 mm, and most preferably around 16 mm; and the bend radius 110 is from about 3 mm to about 4 mm, more preferably to about 8 mm or 10 m, and in one embodiment is about 4.9 mm, and in another is about 3.75 mm.

The bend portions can be made without wall segments, but preferably include the wall segments. Other constructions of wall segments or other internal supports for the pressure-supporting tube walls or other internal channel dividers can alternatively be used. The preferred material is copper or a copper alloy for tubes 44 of heat exchanger 102, although other suitable materials may be used.

While illustrative embodiments of the invention are disclosed herein, it will be appreciated that numerous modifications and other embodiments may be devised by those skilled in the art. For example, welding projections or other structures to promote welding can additionally be provided on the sheet to improve welding to the wall elements. These welding projections on the sheet can be used in conjunction with or instead of, the welding projections on the lateral sides of the wall elements. Additionally, certain embodiments of the wall elements can be made without welding projections, such as shown in FIG. 12. Although some embodiments use sealed wall elements to prevent the flow across the tube internal channels, others permit such flow. Therefore, it will be understood that the appended claims are intended to cover all such modifications and embodiments that come within the spirit and scope of the present invention.

Claims

1. A method of producing a multiple-channel conduit, comprising: providing a plurality of wall elements that are elongated in a longitudinal direction and that have an elongated cross-section transversely to the longitudinal direction, the wall elements having opposite lateral sides disposed on opposite ends of an elongate axis of the cross-section; and adhering the opposite lateral sides of the wall elements to first and second sheet members such that the wall elements are disposed therebetween and defines a plurality of channels between the adhered wall elements and sheet members.

2. The method of claim 1, wherein the elongated cross-section has an aspect ration of at least about 1.2.

3. The method of claim 1, wherein the elongated cross-section has an aspect ratio of at least about 1.5.

4. The method of claim 1, further comprising melting a material to adhere the opposite lateral sides to the sheet members.

5. The method of claim 4, wherein the opposite lateral sides are adhered to the sheet members by welding, brazing, or soldering.

6. The method of claim 4, wherein the opposite lateral sides are welded to the sheet members by applying an electrical current therebetween in an amount sufficient to melt a portion of the material of each sheet members.

7. The method of claim 6, wherein the opposite lateral sides are electrical-resistance welded to the sheet members.

8. The method of claim 1, further comprising compressing wire to form the wall elements.

9. The method of claim 8, wherein the wire is compressed by roll forming.

10. The method of claim 1, wherein the plurality of wall elements are formed with a welding projection extending laterally at the opposite lateral sides and configured promote welding to the sheet members.

11. The method of claim 1, wherein the sheet members are part of a single sheet.

12. The method of claim 11, further comprising bending the sheet around an interior space, wherein the wall elements are adhered to the sheet members within the interior space.

13. The method of claim 12, further comprising adhering lateral ends of the single sheet to enclose and define one of the channels.

14. The method of claim 1, wherein the wall elements have a lateral width between the lateral sides of less than about 10 mm.

15. The method of claim 14, wherein at least one of the sheet members has a sheet thickness of less than about 0.5 mm.

16. The method of claim 1, wherein the wall elements and sheet members are made of copper or a copper alloy.

17. The method of claim 1, wherein the conduit is formed to provide a heat exchanger.

18. The method of claim 1, wherein the exterior of the sheet members adhered to the wall elements is substantially smooth to facilitate sealing to a header.

19. The method of claim 1, further comprising bending at least a portion of the assembled conduit with the wall elements disposed at least along bent portion.

20. A multiple channel heat exchanger, comprising: a plurality of wall elements that are separate from each other and are elongated in a longitudinal direction and that that have an elongated cross-section transversely to the longitudinal direction, the wall elements having opposite lateral sides disposed on opposite ends of an elongate axis of the cross-section; and a sheet surrounding the wall elements; wherein the opposite lateral sides of the wall elements are adhered to the sheet to provide a plurality of channels defined between the adhered wall elements and the sheet members.

21. The heat exchanger of claim 20, further comprising a weld adhering the lateral sides of the wall elements to the sheet.

22. The heat exchanger of claim 20, further comprising a brazing or solder joint adhering the wall elements to the sheet.

23. The heat exchanger of claim 20, wherein the wall elements have a lateral width between the lateral sides of less than about 10 mm.

24. The heat exchanger of claim 20, wherein the wall elements have a lateral width between the lateral sides of less than about 5 mm.

25. A multiple-channel conduit, comprising a tube that comprises comprising: a cross-section with a major and a minor diameter; bend portions that are bent about a radius with a parallel dimension of the cross-section being parallel to said radius; and channel partitions that define channels within the tube, wherein the partitions are provided in the bend portions

26. The conduit of claim 25, wherein the radius is less than about 10 times the parallel dimension, and the conduit is configured along a serpentine pattern.