Heat exchanger with internal slotted manifold

Abstract

A heat exchanger that includes a manifold tube having a plurality of spaced apart openings formed through its wall in flow communication with a flow passageway, and a plurality of stacked flat tube elements each including a first plate and a second plate defining a flow channel therebetween, the plates each being provided with an aperture therethrough, the apertures in the first and second plates being substantially in alignment with each other. The manifold tube is received through the apertures in the first and second plates of each of the flat tube elements with each of the spaced apart openings in flow communication with the flow channel of a respective one of the flat tube elements. During assembly, the wall of the manifold tube is radially enlarged so that an outer surface of the manifold tube engages an inner surface surrounding the aperture in each of the first and second plates to secure the flat tube elements to the manifold tube. Also provided is a stacked plate heat exchanger having a manifold tube with an error proofing hole for ensuring a baffle cup is in place in the manifold tube, and a stacked plate heat exchanger having a manifold tube and a port fixture having an annular flow way in communication with a flow passage in the manifold tube through a plurality of radially spaced openings through the manifold tube.

Description

BACKGROUND OF THE INVENTION

[0001] This invention relates to heat exchangers, and in particular to stacked plate heat exchangers using slotted manifold tubes.

[0002] Current heat exchangers for use in automobiles are well known and are generally of the flat plate type constructed with alternating and adjacent laterally extending fluid flow and air flow passages. Flat plate heat exchangers that use slotted manifold tubes are known, including for example the heat exchangers illustrated in U.S. Pat. No. 5,908,070 (Kato et al.) and U.S. Pat. No. 6,073,686 (Park et al.) in which the opposite ends of flat fluid flow tubes are inserted into slots provided in manifold tubes. Inserted plate type heat exchangers can be cumbersome to assemble, and be prone to leak or otherwise fail at higher fluid pressures.

[0003] Other types of slotted manifold heat exchangers, for example as shown in U.S. Pat. No. 5,560,425 (Sugawara et al.), have been proposed that use flat fluid flow tubes that have flanges for abutting against a portion of the manifold adjacent a corresponding slot in the manifold. Abutting plate type heat exchangers can also be cumbersome to assemble due to difficulties in maintaining manifold and plate alignment prior to brazing, and also may have failure concerns at higher fluid pressures.

[0004] Still a further type of slotted manifold heat exchange is illustrated in U.S. Pat. No. 3,605,882 (P. R. Smith et al.) in which the manifold is inserted through holes provided in the flat fluid flow tubes, with tube spacers being positioned on the manifold between adjacent flat tubes in order to secure the flat tubes in place. Such a configuration can be complex to assemble. Another slotted manifold heat exchanger can be seen in U.S. Pat. No. 2,511,084 (J. C. Shaw), in which the manifolds are also inserted through holes provided through core elements. In such a configuration, the core elements are secured together by bolts, independently of the manifolds.

[0005] Thus, there is a need for a slotted manifold heat exchanger that is easy to assemble and that is high pressure resistant. A heat exchanger and corresponding assembly method that require relatively little manufacturing adjustments or retooling to produce heat exchangers of varying length, width or height are also desirable.

SUMMARY OF THE INVENTION

[0006] According to one aspect of the invention, there is provided a heat exchanger that includes a manifold tube having a wall defining a flow passage therethrough and having a plurality of spaced apart openings formed through the wall in flow communication with the flow passageway, and a plurality of stacked flat tube elements each including a first plate and a second plate defining a flow channel therebetween, the plates each being provided with an aperture therethrough, the apertures in the first and second plates of each of the tube elements being substantially in alignment with each other. The manifold tube is received through the apertures in the first and second plates of each of the flat tube elements with each of the spaced apart openings in flow communication with the flow channel of a respective one of the flat tube elements. The wall of the manifold tube and the apertures are respectively sized that an outer surface of the manifold tube engages an inner surface surrounding the aperture in each of the first and second plates to secure the flat tube elements to the manifold tube, the flat tube elements being supported by the manifold tube. The openings formed through the manifold tube wall may vary in size along a length of the manifold tube.

[0007] According to another aspect of the invention, there is provided a method of assembling a stacked plate heat exchanger, including steps of (a) providing a manifold tube having a wall defining a flow passage therethrough and having a plurality of spaced apart openings formed through the wall in flow communication with the flow passageway; (b) providing a plurality of flat tube elements each including a first plate and a second plate defining a flow channel therebetween, the plates each being provided with an aperture therethrough, the apertures in the first and second plates of each of the flat tube elements being substantially in alignment with each other; (c) positioning the manifold tube through the apertures in the first and second plates of each of the flat tube elements with each of the spaced apart openings in flow communication with the flow channel of a respective one of the flat tube elements; and (d) radially expanding at least portions of the manifold tube such that manifold tube engages each of the first and second plates about the apertures thereof to secure the flat tube elements to the manifold tube. The heat exchanger may be brazed after expansion of the manifold tube.

[0008] According to another aspect of the invention there is provided is a heat exchanger comprising a manifold tube having a wall defining a fluid flow passage therethrough and a stack of flat tube elements connected to the manifold tube and each having a flow channel therethrough in fluid communication with the fluid flow passage. A baffle cup having a wall engages an inner surface of the manifold tube wall, the manifold tube wall having an error proofing hole formed therethrough at a location where the baffle cup wall is positioned, the hole being sized such that a visual check can be performed to ensure that the baffle cup is in place. The error proofing hole is sealably covered by the wall of the baffle cup.

[0009] According to still another aspect of the invention, there is provided a heat exchanger comprising a manifold tube having a wall defining a fluid flow passage therethrough, a stack of flat tube elements connected to the manifold tube and each having a flow channel therethrough in flow communication with the fluid flow passage, and a port fixture having a collar providing an annular flow way surrounding an annular area of the manifold tube wall having a plurality of radially spaced openings formed therethrough. The annular flow way is in flow communication with the fluid flow passage through the radially spaced openings, the port fixture having a connecting member extending from the collar and defining a fluid passageway in flow communication with the annular flow way.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Preferred embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which:

[0011] FIG. 1 is an elevational view of a preferred embodiment of a flat plate heat exchanger according to the present invention;

[0012] FIG. 2 is a perspective view of the heat exchanger of FIG. 1;

[0013] FIG. 3 is a partial sectional perspective view of the heat exchanger of FIG. 1;

[0014] FIG. 3A is a partial sectional elevational view showing an inlet port mounted to a manifold tube of the heat exchanger;

[0015] FIG. 4 is a plan view of a plate pair tube element of the heat exchanger of FIG. 1;

[0016] FIG. 5 is an exploded elevational view of a plate pair tube element;

[0017] FIG. 6 is a perspective view of a turbulizer of the plate pair tube element;

[0018] FIG. 7 is an elevational view of a manifold tube of the heat exchanger;

[0019] FIG. 8 is a plan view of the manifold tube;

[0020] FIG. 9 is a perspective view of a bracket for the heat exchanger according to one embodiment of the invention;

[0021] FIG. 10 is a schematic illustration of an assembly process for the heat exchanger;

[0022] FIG. 11 is a partial sectional perspective view of the heat exchanger of FIG. 1, showing a hydraulic bladder being used to expand a manifold tube;

[0023] FIGS. 12A and 12B illustrate, in elevational view, the use of a tapered pin mandrel to expand a manifold tube;

[0024] FIG. 13 is a partial elevational view showing a manifold tube having slot openings in accordance with a further embodiment of the invention;

[0025] FIG. 14 is a partial elevational view showing a manifold tube having slot openings in accordance with still a further embodiment of the invention;

[0026] FIG. 15 is a partial elevational view showing a flat tube element mounted on a manifold tube in accordance with a further embodiment of the invention;

[0027] FIG. 16 is a partial elevational view showing a manifold tube having slot openings in accordance with a further embodiment of the invention;

[0028] FIG. 17 is a simplified elevational view showing a further embodiment of a heat exchanger in which a baffle cup is used to separate the manifold tubes;

[0029] FIG. 18 is a sectional perspective view of a baffle cup;

[0030] FIG. 19 is a partial elevational view showing an error proofing hole for the baffle cup;

[0031] FIG. 20 is a simplified elevational view of yet a further embodiment of a heat exchanger according to the present invention;

[0032] FIG. 21 is a plan view of the heat exchanger of FIG. 20;

[0033] FIG. 22 is a partial sectional perspective view of a heat exchanger according to another embodiment of the invention;

[0034] FIG. 23 is a plan view of a bracket of the heat exchanger of FIG. 22;

[0035] FIG. 24 is a plan view of a further bracket configuration;

[0036] FIG. 25 is a plan view of yet a further bracket configuration;

[0037] FIG. 26 is a sectional plan view of a further port fitting mounted on a tube manifold;

[0038] FIG. 27 is an elevational view of the further port fitting;

[0039] FIG. 28 is an elevational view of yet another port fitting;

[0040] FIGS. 29 and 30 are partial sectional perspective views of further flat tube element embodiments; and

[0041] FIG. 31 is a elevational view of still a further embodiment of a heat exchanger according to the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0042] The structure, operation, and method of assembly of the heat exchanger of the subject invention will now be described, with like reference numerals used throughout to refer to similar parts of different embodiments of the heat exchanger.

[0043] Referring to FIGS. 1, 2 and 3, a flat plate heat exchanger according to one preferred embodiment of the present is shown generally by reference numeral 10. The heat exchanger 10 is a single pass heat exchanger which may be used in an automotive application such as a transmission oil cooler or power steering fluid cooler, however the features of the present invention can be applied to a wide range of heat exchangers for different applications and the heat exchanger 10 of FIG. 1 is provided as just one example of a heat exchanger according to the present invention. The heat exchanger 10 includes a first manifold tube 12 and second manifold tube 14, which in the single pass configuration illustrated function as an intake manifold tube and an out take manifold tube respectively. A plurality of elongate flat tube elements 16 are arranged in parallel fashion on the manifold tubes 12,14. The flat tube elements 16 each include a first plate 18 and a second plate 20 sealed together to form a flow passage way 21 there between. Air passages 22 are located between adjacent flat tube elements 16, and corrugated fins 24 are located in air passages 22, fins 24 being in thermal contact with adjacent flat tube elements 16 for providing a high surface area for heat exchange between the fins 24 and air flowing through the air passages 22.

[0044] As best seen in FIG. 3, the manifold tube 12 includes a series of slots 42 that are longitudinally spaced along and extend through the cylindrical wall of the manifold tube 12. The slots 42 are arranged so that their length runs transverse to the longitudinal axis of the manifold tube 12. The flat tube elements 16 are each arranged along the manifold 12 so that each of the tube elements 16 is aligned with a respective one of the tube slots 42, and more particularly, so that the fluid passage 21 provided through each of the tube elements 16 is in flow communication with the passage 30 provided through the manifold tube 12 through the respective openings provided by manifold tube slots 42.

[0045] Similar slots are provided along the cylindrical wall of the out take manifold tube 14, and the out take ends of the flat tube elements 16 are arranged on the out take manifold 14 such that an out take end of each of the fluid passages 21 provided through the flat plate tube elements 16 communicates with the flow passage 34 provided through the out take manifold tube 14 by way of the slots provided along the out take manifold tube 14.

[0046] A fluid inlet port 26 is provided on the intake manifold tube 12 and a fluid outlet port 28 is provided on the out take manifold tube 14. The inlet and outlet ports 26, 28 are shown in arbitrary locations along their respective manifold tubes in FIGS. 1 to 3. The inlet port 26 defines a passage that is in flow communication with a fluid flow passage 30 provided through the interior of intake manifold tube 12 such that a fluid can flow through the inlet port 26 into the interior of the manifold tube 12 as illustrated by arrow 32 in FIG. 3. Similarly, the outlet port 28 defines a flow passage in communication with a flow passage 34 defined by an interior surface of the out take manifold tube 14. In the illustrated embodiment, end plates 36 and 38 without flow passages there through are provided as the first and last plate on the heat exchanger 10.

[0047] End caps 40, which are shown in exploded view in FIGS. 1 and 2, can conveniently be used to seal the ends of the intake and out take manifold tubes 12, 14. Brackets 43 may be positioned along the manifold tubes 12, 14 to permit the heat exchanger 10 to be secured in position.

[0048] Thus, during operation of the heat exchanger 10, the fluid to be cooled enters the heat exchanger 10 through the inlet port 26 and flows into the passage 30 in the intake manifold tube 12. From the intake manifold tube 12, the fluid is dispersed through slots 42 into the plurality of fluid passages 21 that are provided through the flat tube elements 16. The fluid exits the fluid passages 21 through corresponding slots provided on the out take manifold tube 14 to enter the fluid passage 34 provided by the out take manifold tube 14. As the fluid travels across the heat exchanger 10 through the fluid passages 21, its heat energy is drawn off by corrugated fins 24, which in turn are cooled by air flowing through the air passages 22. The cooled fluid leaves the out take manifold tube 14 through the outlet port 28.

[0049] An overview of the heat exchanger 10 having been provided, the details of the structure and fabrication of the elements of the heat exchanger 10 will now be discussed in greater detail with reference to the Figures.

[0050] As can be seen in FIGS. 1-3, the flat tube elements 16 each include openings at their opposite ends through which the manifold tubes 12 and 14 are internally received. With reference to FIGS. 4 and 5, which show a top plan view and an exploded elevational view, respectively, of a preferred embodiment of one of the flat tube elements 16, each of the first and second plates 18,20 includes a elongate substantially planar central portion 56. Inwardly offset flanges 58 are located along the longitudinal edges of the plates 18 and 20, forming longitudinal peripheral edges. End flanges 60 extend between the ends of longitudinal flanges 58, thus forming end edges on the plates 18, 20. Thus, flanges 58 and 60 collectively form a continuous inwardly offset edge portion that surrounds the planar central portion 56. When the plate pairs 18 and 20 are joined together, the offset longitudinal flanges 56 of one plate abut against the longitudinal flanges of the other plate, and similarly the end flanges 60 of plate abut against the end flanges 60 of the other plate. As will be explained in greater detail below, in one preferred embodiment the first and second plates 18, 20 are sealably connected along the longitudinal edges and end edges thereof through a brazing process. In some embodiments, soldering or adhesive bonding could be used.

[0051] The longitudinal flow passage 21 is defined between the central planar portions 58 of the first and second plates 18, 20. A turbulizer or turbulator 62 is, in a preferred embodiment, located within the fluid channel 21 that is formed between the planar portions 56. Greater detail of one possible turbulizer 62 configuration is shown in FIG. 6. The turbulizer 62 includes a series of undulations or convolutions formed therein to create turbulence in the fluid flow and in this way increase heat transfer in the heat exchanger. In some embodiments, turbulizers may not be used, or could be replaced by dimples, ribs or ripples formed on the plates 18,20.

[0052] With reference to FIG. 4, an opening 44 is provided through one end of the flat tube element 16 for receiving the intake manifold tube 12, and a second spaced-apart opening 46 is located at the other end of the flat tube element 16 for receiving the out take manifold tube 14. With reference to FIG. 5, the opening 44 is provided by aligned apertures 48 that are pierced through the first and second plates 18, 20, and similarly, opening 46 is provided by aligned apertures 50 that are pierced through opposite ends of the plates 18, 20. The apertures 48 and 50 are pierced through end portions of the outwardly offset planar portions 56 such that when the flat tube elements are assembled, the openings 44 and 46 are both in flow communication with the fluid passage 21 that is defined between the plates 18, 20. As best seen in FIG. 3A and 4, the apertures 44,46 are, in a preferred embodiment, arranged such that an annular portion 23 of the flow channel 21 extends around the circumferences of the manifold tubes.

[0053] A peripheral flange 64 defines an inner circumference of each of the apertures 48. The flange 64 extends outward (i.e. away from the flow channel) from the outer surface of the central planer portion 56. The peripheral flanges 64 are integrally formed on their respective plates, and provide an overlap joint between the flat tube elements 16 and the respective manifold tubes 12,14, as can best be seen in FIG. 3A.

[0054] In a preferred embodiment, the plates 18, 20, are roll formed to form the central planar portion 56 and longitudinal flanges 58, after which the roll formed raw plate is lanced at a desired length and peripheral end flanges 60 are end formed. The apertures 48 and 50 are formed by piercing and subsequently extruding the peripheral flange 64. As shown in FIG. 4, the longitudinal flanges 58 can extend further into the centre of the plates 18, 20 near the apertures 48, 50 to form shoulders 59 to abut against each other to support the plates 18,20 near the openings 44,46, but still provide the annular flow path 23 around the outer facing portions of the manifold tubes. Shoulders 59 provide increased strength around the apertures 48,50.

[0055] The use of roll formed plates conveniently allows plates of varying lengths to be made with minimal assembly line changes required. Plates 18,20 could also be formed using other techniques, including for example, stamping, however such alternatives may not be as flexible as roll forming for permitting changes in plate length.

[0056] FIG. 7 shows an elevational view of a preferred embodiment of the intake manifold tube 12, which is basically a cylindrical wall having manifold tube slots 42 spaced along a length thereof. In one preferred embodiment, an inlet opening 68 is provided for the inlet port 26. An outwardly extending flange 70, which in the illustrated embodiment is annular, is optionally provided at one end of the manifold tube 12 in order to provide a stop for the end plate 36 or 38 during assembly of the heat exchanger. The slots 42 are preferably formed by using a die punch with internal die support, or a saw, however it would be appreciated that other slot forming methods could be used, for example, saw cutting, milling, piercing, laser cutting, or lancing.

[0057] With reference to FIG. 8, an outer diameter of the manifold tube 12 is illustrated as having a dimension D1. Prior to assembly of the heat exchanger 10, the outer diameter D1 is less than an inner diameter D2 (see FIG. 4) of the opening 44 through the plate pair 16, in order to allow the plate pair 16 to be slidably mounted on the manifold 12. The out take manifold tube 14 is basically identical to the intake manifold tube 12, and has an outer diameter D1 that, prior to assembly, is less than an inner diameter D2 of the opening 46 through each of the flat tube element 16 so that the plate pair elements can be mounted thereon.

[0058] With reference to FIG. 3A, in a preferred embodiment, the inlet port 26 includes a cylindrical collar 98 through which the intake manifold tube 12 can pass. A cylindrical connecting wall 100 defining an inlet passage extends transversely from the collar 98. Conveniently, the collar 98 can be supported by the peripheral flanges 64 of opposing flat tube elements as illustrated in FIG. 3A in such a manner that it can be pivoted to a desired position during heat exchanger assembly prior to manifold tube expansion. In the illustrated embodiment of FIGS. 1 to 3, the outlet port 28 is identical to and mounted in the same manner as the inlet port 26.

[0059] FIG. 9 shows in greater detail a mounting bracket 43 according to one embodiment of the invention for use on the intake or out take manifold tube 12,14 side of the heat exchanger 10. Each mounting bracket 43 has first clip part 146 including spaced-apart C-shaped clips 148, 149, each of which defines respective contacting surfaces 150, and a central portion or spacer member 152 extends between and connects the clips 148,149. A second clip part 154, has spaced apart C-shaped clips 156,157. Each clip 156,157 defines a respective contacting surface 158. A central portion or spacer member 160 extends between and connects the clips 156,157. The C-shaped clips 148, 149 are dimensioned to receive one flat tube element 16, and the C-shaped clips 156, 157 a second flat tube element 16. Preferably, the C-shaped clips are dimensioned to frictionally engage their respective flat tube element with sufficient force to hold the bracket in place until brazing occurs.

[0060] The inlet and outlet ports 26, 28 and brackets 43 as described above are only one example of several different inlet and outlet port and bracket configurations that can be used with the present invention, and examples of further alternatives will be provided further below. Alternative manifold tube and flat tube element configurations to those described above can be used as well, and examples of further alternatives will also be provided below. But first, a description of the elements of a preferred embodiment of the heat exchanger 10 having been provided, assembly of the elements to form the heat exchanger 10 will now be described.

[0061] With reference to the schematic flowchart of FIG. 10, as indicated by brace 92, in one preferred assembly method a core heat exchanger stack (indicated by reference numeral 108 in FIG. 11) is assembled from end plates 36,38, first and second plates 16, 18, turbulizers 62 and fins 24. In particular, the end plate 38 is positioned (step 90-1) and a fin 24 placed along it (step 90-2), after which a first plate 16 is added (step 90-3), followed by a turbulizer 62 (step 90-4), followed by a second plate 18 (step 90-5) such that the first and second plates 16,18 define fluid flow channel 21 therebetween in which the turbulizer 62 is positioned. As indicated in FIG. 10 by line 94, building up the core stack through the method sequence of adding a fin 24, a first plate 16, a turbulizer, and a second plate 18 continues until the core stack reaches a predetermined height (which, in the example shown in FIGS. 1-3, includes five plate pairs), after which a final fin 24 is added and the core stack topped off with end plate 36 (step 90-6). As the core stack 108 is being assembled, all the core stack components are aligned as illustrated in FIGS. 1 to 3, with plate apertures 48 substantially aligned and plate apertures 50 substantially aligned. End plates 38 and 36 also have corresponding apertures provided there through.

[0062] Preferably, fittings, namely the inlet and outlet ports 26,28 and brackets 43 are then positioned on the core stack 108 as required (step 90-7). Once the fittings and brackets are added to the core stack, the manifold tubes 12 and 14 are slidably inserted through the corresponding aligned apertures in the assembled core stack (step 90-8). The annular flanges 70 on the ends of the manifold tubes 12 and 14 act as stop members to assist in positioning the manifold tubes. Preferably, the core stack 108 is then compressed (step 90-9) until the slots 42 in the manifold tubes 12 and 14 are each aligned with a respective flow channel 21 through a corresponding flat tube element 16.

[0063] The manifold tubes 12 and 14 are each then internally expanded to increase their respective outer circumferences so that they each securely engage an inner circumference of the apertures 48 and 50, respectively, of each of the plates 18 and 20 thereby effectively locking the plate pairs 16 in place (step 90-10). As mentioned above, prior to expansion, the manifold tubes 12 and 14 each have a respective outer diameter D1 (FIG. 8) that is less that an inner diameter D2 (FIG. 4) of the corresponding plate apertures 48 and 50, in order to facilitate assembly of the heat exchanger. During expansion, at least the portions of the manifold tube walls adjacent the plate apertures 48 and 50 are enlarged such that the enlarged diameter exceeds the inner diameter D2 of the apertures. Thus after expansion, the enlarged manifold tubes 12 and 14 each engage substantially the entire circumference of the plate apertures 48 and 50, respectively (in the preferred embodiment that is shown in the drawings, an overlap joint is formed between each of annular flange 64 and the manifold tubes that it surrounds), preventing any further movement of the plates 16,18 relative to the enlarged manifold tubes 12 and 14.

[0064] With reference to FIG. 11, in one preferred embodiment a hydraulic bladder 102 is placed inside each of the manifold tubes 12 and 14, and expanded by pumping hydraulic fluid through an inlet 106 to radially enlarge the manifold tubes in a substantially uniform manner along their entire lengths through radial pressure applied uniformly throughout the manifold tubes in the direction indicated by arrows 104. The use of a uniform radial pressure along the length of the manifold tubes decreases any axial loading during the expansion process. Axial loading is generally not desired, especially in longer manifold tubes, as it can result in deformation that is exacerbated by the slotted nature of the manifold tubes.

[0065] It will be appreciated that alternative expansion methods can also be used. For example, in shorter manifold tubes where axial loading is not as great a concern, a tapered pin mandrel can be used to expand the manifold tubes. FIGS. 12A and 12B show pre-expansion and post-expansion, respectively, views illustrating the use of a stepped tapered pin mandrel 106 to radially expand the manifold tube 14 in the vicinity of each of the slots 42 to achieve locally pronounced expansion at the points along the manifold tube 14 where the flat tube elements (not shown in FIGS. 12A and 12B) are engaged by the manifold tube. If desired, in embodiments in which a hydraulic bladder is used to effect expansion, bands could be provided around the bladder to localize expansion at the points along the manifold tubes in the manner shown in FIG. 12B.

[0066] With reference again to FIG. 10, subsequent to manifold tube expansion, end caps 40 are placed on the manifold tubes 12 and 14, for example by a swage or press-fit operation (step 90-11), after which the entire heat exchanger 10 assembly is sent to a brazing oven (step 90-12). At least the first and second plates 18, 20 of the heat exchanger are preferably braze clad such that in the brazing oven, the flat tube elements are sealaby brazed along their respective edges, the peripheral flanges 64 about the plate apertures 48, 50 are sealably brazed about their entire circumferences to the manifold tubes 12,14, respectively, the end caps 40 are sealably brazed in place, and the fins 24 and end plates 36,38 are all secured by brazing.

[0067] Compression of the core stack 108 (step 90-9) prior to radial expansion of the manifold tubes is performed in the preferred assembly method to compensate for shrinkage of the core stack that occurs during brazing. In some heat exchanger configurations, if the flat tube elements are locked in place by expansion of the manifold tubes without pre-compression of the core stack, then the centre area of the core stack may bow inwards due to shrinkage in the brazing oven. Preferably, compression of the core stack is applied preferentially to the core plate stack 108 in the areas closer to the manifold tubes 12,14, where the greatest resistance to compression will generally be experienced.

[0068] The core plate stack 108 could be assembled using methods differing from that shown in FIG. 10. For example, in an alternative preferred embodiment, the manifold tubes 12,14 are loaded into a fixture, and the core plate stack 108 built up by sliding the plates onto the manifold tubes one at a time, or in groups, along with alternating fins and turbulizers, rather than assembling the entire core plate stack 108 and then inserting the manifold tubes as described above in respect of FIG. 10.

[0069] The configuration of the present invention provides a heat exchanger with a relatively high burst strength as the slotted manifold tubes 12,14 are supported internally within the apertures of each of the plates 18,20. Such configuration also provides a relatively strong joint between each of the flat tube elements and each of the manifold tubes. Assembly is uncomplicated as the use of expanded manifold tubes to secure the plates 18,20 in place prior to brazing reduces the need for any additional spacers or collars to be mounted on the manifold tubes to hold the plates in position.

[0070] With relatively few assembly line changes, the heat exchanger configuration and assembly method of the present invention can be used to produce a number of variations of the heat exchanger. For example, heat exchangers of different heights can be produced by using longer or shorter manifold tubes (for taller and shorter heat exchangers, respectively) and a corresponding increased or decreased number of flat tube elements and fins. Heat exchangers of different lengths (as measured from manifold tube to manifold tube in the illustrated embodiment) can be produced by roll forming longer or shorter first and second plates 18, 20, and longer or shorter end plates 36,38, and using longer or length-wise shorter fins 24. Heat exchangers of different widths can be produced by roll forming wider or narrower first and second plates 18, 20, and wider and narrower end plates 36,38, and using wider or narrower fins. If desired, larger or smaller diameter tube manifolds can be used with corresponding changes being made to the apertures pierced through the plates 18,20. The spacing between flat tube elements 16 can be changed by changing the spacing of the manifold slots 42 along the tube manifolds 12,14, and using higher or lower fins 24. It will thus be appreciated that features of the present invention can be used in the production of heat exchangers having varied length, width and height, without significant assembly line tooling changes.

[0071] The present invention also provides flexibility in fitting and bracket placement. The location of inlet and outlet ports 26, 28, can be varied relatively easily by using manifold tubes with inlet and outlet openings 68 in a different location, and then adding the inlet and/or outlet ports 26, 28 to the core stack 108 at a location corresponding to the different inlet and/or outlet openings. In practice the positions of the fittings in this invention can easily be adjusted to suit heat exchanger flow distribution constraints or to correspond to preferred fluid supply connector locations. One or both of the manifold tubes 12,14 could also be configured without side inlets or outlets, and instead have an inlet or outlet, respectively, at a manifold tube end rather than an end cap 40.

[0072] Some examples of alternative preferred embodiments of the present invention will now be described.

[0073] It will be appreciated that in some embodiments, the slots 42 may be replaced by openings of a different configuration, for example circular or oval, or each individual slot 42 could be replaced with a plurality of openings. By way of example, FIG. 13 shows a manifold tube 14 having radial rows of circular openings 172 and radial rows of square openings 174 in place of slots 42. Such openings may be radially located about part of or the entire circumference of the manifold tube.

[0074] In a further preferred embodiment of the invention, the sizes of the slots 42 along one or both of the manifold tubes 12, 14 are varied along the length thereof. For example, with reference to FIG. 14, in such further preferred embodiment, the opening defined by the slot 42 designated by S2 is larger than the opening defined by the slot 42 designated by S1. The larger size of slot 42-S2 may be the result of slot 42-S2 having a greater height than slot 42-S1 (slot height being parallel to the longitudinal axis of the manifold tube 14), or may be the result of slot 42-S2 having a greater length than slot 42-S1 (slot length being transverse to the longitudinal axis of the manifold tube), or may be a result of both of these factors. In embodiments where a plurality of openings are used in the place of a single slot, the same effect can be achieved by using more openings to communicate with the flow channels of flat tube elements where a larger opening area is desired. Varying the size of the slot openings along the manifold tubes may be used to improve flow distribution through the heat exchanger 10. In the embodiment of FIG. 14, the slot openings become progressively larger from the bottom to the top of the manifold tube 14. In some embodiments, the slots may be grouped with slot size increasing progressively for groups of slots, with for example a group of three longitudinally adjacent slots having the same size, and then the next three slots having a different size and so on. The size of the respective slot openings through the intake and out take manifold tubes 12, 14 in flow communication with the inside channel through a given flat tube element 16 need not be identical in all applications, however slot to slot centre spacing on the two manifold tubes should be substantially identical to maintain proper plate pair spacing throughout the core stack 108.

[0075] The height of slots 42 is limited to less that the distance between the plates 18 and 20. Larger slot heights can be used if the spacing between the plates 18 and 20 is increased in the area around the manifold tubes. By way of example, FIG. 15 shows an embodiment of the invention in which the spacing between first and second plates 18 and 20 of tube element 16 is increased in an annular area 110 surrounding the manifold tube 14 to accommodate a slot 42 having a height greater than the flow channel defined by planar portions 56.

[0076] The slots 42 along the manifold tubes 12,14 may, in some embodiments of the present invention, be directed in some other manner than inward towards the centre of the heat exchanger. For example, FIG. 16 shows an out take tube manifold 14 in which the slots 42 face the ends 60 of the plates making up flat tube elements 16, rather than facing towards the centre of the heat exchanger. Such a configuration forces the fluid flowing through the flat tube elements 16 into the ends of such elements.

[0077] In some embodiments of the invention, spacing of the slots 42, and the corresponding spacing of the flat tube elements 16 may be varied along the length of the manifold. For example, with reference to FIG. 7, spacing H1 could be different than spacing H2.

[0078] Another embodiment of a heat exchanger according to the present invention is shown in a simplified view indicated by reference number 111 in FIG. 17. The heat exchanger 111 is similar in construction and operation to the heat exchanger 10 as described above except for the differences noted below. As with heat exchanger 10, the heat exchanger 111 includes a stack of alternating fins 24 and flat tube elements 16 that extend between a first manifold tube 12′ and a second manifold tube 14′. The manifold tubes 12′ and 14′ each have spaced apart slots along their respective lengths that connect flow passages inside the manifold tubes 12′ and 14′ with flow channels in the flat tube elements 16. However, cup baffles 112 are sealably secured inside each of the manifold tubes 12′ and 14′, effectively turning the heat exchanger into two separate heat exchangers, as identified by reference numbers 114 and 116, for two different fluids. In the illustrated embodiment of the heat exchanger 111, as indicated by arrow 118, a first fluid flows into the portion of the manifold tube 12′ above the cup baffle 112. The first fluid then flows through slots in the upper portion of manifold tube 12′, through corresponding plate pair flow tubes 16, and subsequently into the out take manifold tube 14′, and then out of the manifold tube 14′ as indicated by arrow 120. As indicated by arrow 122, a second fluid flows into the portion of the manifold tube 12′ below the cup baffle 112. The second fluid then flows through slots in the lower portion of manifold tube 12′, through corresponding plate pair flow tubes 16, and subsequently into the out take manifold tube 14′, and then out of the manifold tube 14′ as indicated by arrow 124. In such embodiment, the first and second fluids are kept separated in the heat exchanger 111. Various features could be varied between the two sub-heat exchangers 114, 116 depending on the desired treatment for the first and second fluids. For example, higher flat tube element 16 spacing could be used for one sub-heat exchanger than the other and/or larger manifold slots could be used in one sub-heat exchanger than in the other.

[0079] In some configurations a baffle cup 112 having a calibrated opening therethrough may be located in either one or both of the intake or out take manifold tubes 12′ and 14′ to control fluid flow therein. In some embodiments, baffle cups may divide only one of the manifold tubes 12′, 14′, and only a single fluid be used in the heart exchanger, which then assumes a double pass configuration. For example, a baffle cup 112 could be used only in the first manifold tube 12′ to divide it in two chambers as indicated in FIG. 17, the baffle cup 112 in second manifold tube 14′ omitted, and the second manifold tube 14′ capped with no outlet or inlet ports provided therein. In such configuration, fluid would flow into the portion of first manifold tube 12′ above the baffle cup 112 as indicated by arrow 118, through the upper three flat tube elements 16 shown in FIG. 17 and into the second manifold tube 14′, then into the three lower flat tube elements 16, and back into the first manifold tube 12′ below the baffle cup 112, and out of the manifold tube 12′ in the opposite direction of arrow 122. From this example, it will be appreciated that further baffle cups could be used to configure the heat exchanger as a multi-pass exchanger.

[0080] The baffle cups 112 can each be stamped from a brazing sheet, and will typically be installed after manifold tube expansion has been carried out. An example of one possible configuration of a baffle cup 112 is shown in greater detail in FIG. 18, in which the baffle cup 112 includes a circular disc like member 113 having an cylindrical wall 115 formed about its outer peripheral edge. Wall 115 provides an overlap joint with the wall of the manifold tube 12′ or 14′ in which the baffle cup 112 is inserted. Preferably the baffle cup is sized so that the circumference of the outer surface of wall 115 is small enough to slidably fit into the expanded manifold tube 12′ or 14′, but large enough to frictionally engage the inner surface of the wall of the manifold tube 12′ or 14′ so that the baffle cup 112 does not move unintentionally prior to brazing once positioned in place. In one embodiment, the baffle cup 113 is inserted into its respective manifold tube using a rod fixture of calibrated length to correctly position the baffle cup. In a preferred embodiment of the invention, an error proofing hole 117 is provided through the wall of the manifold tubes 12′, 14′ in alignment with the location where the baffle cup 12 should be positioned once installed. As seen in FIG. 19, the error proofing hole 117 is positioned to align with and be covered by the baffle cup wall 115 when the baffle cup is mounted in the manifold tube 12′, 14′. The error proofing hole 117 provides for a visual check to ensure the baffle cup is in place as an operator can look into the hole to ensure that it is blocked by wall 115. The error proofing hole 117 also provides a functional check as a test fluid fed into the manifold tube will leak out of the hole if the baffle cup 112 is not sealably in place. It will be appreciated that the baffle 112 and error proofing hole 117 combination could be used for flat plate tube heat exchanger configurations other than the expanded manifold tube configuration of the present invention.

[0081] The heat exchanger of the present invention could be divided into separate sub-heat exchangers using configurations other than the baffle cup divided configuration shown in FIG. 17. In this regard, FIGS. 20 and 21 illustrate yet another embodiment of a heat exchanger 126 of the present invention. The heat exchanger 126 is similar to the heat exchanger 10 described above, except for the differences noted below. Like the heat exchanger 10, the heat exchanger 126 includes a stack of alternating flat tube elements 16(1)-16(4) and fins 24. However, the heat exchanger includes a pair of intake manifold tubes 12A and 12B, and a pair of out take manifold tubes 14A and 14B. As illustrated in FIG. 21, the manifold tubes 12A, 12B, 14A and 14B are each internally received through openings provided through each of the flat tube elements 16(1)-16(4). The intake manifold tubes 12A and 12B are slotted so that neither intake manifold tube is in flow communication with the same flow channel 21 through the same flat tube element, and similarly the out take manifold tubes 14A and 14B are slotted so that neither out take manifold tube is in flow communication with the same flow channel 21 through the same flat tube element. For example, in the illustrated embodiment, the first intake manifold 12A receives a first fluid through an inlet port as indicated by arrow 128. The first intake manifold 12A has slots in communication with the flow channels through flat tube elements 16(1) and 16(3), but does not include slots along the portions of its length that pass through flat tube elements 16(2) or 16(4). Similarly the first out take manifold tube 14A has slots in communication with the flow channels through flat tube elements 16(1) and 16(3), but does not include slots along the portions of its length that pass through flat tube elements 16(2) or 16(4), such that the first fluid passes from the first intake tube manifold 12A through flat tube elements 16(1) and 16(3) to the first out take manifold 14A, and out of the heat exchanger through an outlet port as indicated by arrow 134.

[0082] Each of the second intake manifold tube 12B and the second out take manifold tube 14B have manifold slots 42 in communication with the flow channels through flat tube elements 16(2) and 16(4), but not with alternating flat tube elements 16(1) and 16(3). Thus, a second fluid can flow into the second intake manifold tube 12B as indicated by arrow 130, through the flat tube elements 16(2) and 16(4) into second out take tube manifold 14B, and then out of the heat exchanger as indicated by arrow 132. As best seen in FIG. 21, the inner manifold tubes 12B and 14B preferably have smaller diameters than the outer manifold tubes 12A and 14A in order to facilitate flow of the first fluid by the inner manifolds as indicated by arrows 136 and 138. Conveniently, the manifold slots 42 on the inner manifold tubes 12B and 14B can be outwardly directed (i.e. towards the outer manifold tubes 12A and 14A) in order to force the second fluid to travel closer to the outer ends of the heat exchanger.

[0083] As noted above, the heat exchanger configuration of the present invention permits different fittings and brackets to be used. In this regard, FIG. 22 illustrates yet another embodiment of a heat exchanger 178 of the present invention. The heat exchanger 178 is similar to the heat exchanger 10 described above, except that inlet and outlet ports 26 and 28 are replaced by differently configured inlet and outlet ports 182 (inlet port not shown in FIG. 22), and brackets 43 have been replaced by differently configured mounting brackets 180.

[0084] The bracket 180 includes an L-shaped mounting plate 184 that is connected to a cylindrical wall forming a closed collar 186 that is sized to receive wall of a manifold tube 12 or 14 therein. FIG. 23 shows a plan view of the bracket 180 having closed collar 186. Other bracket configurations can be used in which an open snap-on style collar is used. For example FIG. 24 shows a further bracket 188 having a hook shaped open collar 190 for engaging the manifold tube between two flat tube elements, and FIG. 25 shows a bracket 192 having a Y-shaped open collar having opposed semi-circular portions 194 for engaging the manifold tube. The hook shaped collar 190 and collar portions 194 are preferably braze clad and appropriately dimensioned and sufficiently resilient so that the brackets 188, 192 can be snapped on the manifold tube at a desired location and will stay in place until brazing. Alternatively, the collar 190 and collar portions 194 could be crimped to secure them in place.

[0085] Turning again to FIG. 22, as indicated above, an alternative port fitting 182 is shown mounted to the manifold tube 14. The port fitting 182, which can function as either an inlet or outlet port, is shown in sectional plan view and elevational view, respectively, in FIGS. 26 and 27. Fitting 182 includes an annular collar 200 for receiving the manifold tube 12 or 14. The collar 200 includes a cylindrical wall 202 that is capped on opposite ends thereof by disk-like end plates 204 and 206, each of which has a circular opening 208 therethrough for receiving the manifold tube 12 or 14. The inner surfaces of the cylindrical wall 202 and end plates 204,206 collectively define an internal cavity 210 through which the manifold 12 or 14 passes. The internal cavity 210 has diameter, transverse to the longitudinal axis of tube manifold 12,14, that, is greater than the diameter of the tube manifold 12, 14 such that an annular flow passage 212 is defined between the tube manifold 12,14 and the inner surface of wall 202. A cylindrical connecting member 214 extends radially from the outer surface of the collar wall 202, and the connecting member 214 defines an fluid flow passage 216 that is in flow communication, through an opening 218 provided in the wall 202, with the annular flow passage 212. A frustal-conical flange is provided at an extending end of the connecting member 216 for internally engaging a connector hose or like flow passage connected to the connecting member 216.

[0086] The port fitting 182 is intended to be used in conjunction with a manifold tube 12,14 having a plurality of radially spaced flow openings 222 provided therethrough which are each in flow communication with the annular passage 212. The port fitting and manifold tube combination of FIGS. 22, 26 and 27 permits fluid to be forced into or drawn from multiple locations about the radius of the manifold tube, providing improved flow management in some heat exchanger applications. The annular collar 200 preferably has a height that corresponds to the spacing between two flat tube elements 16 so that it can fit between adjacent tube elements as shown in FIG. 22.

[0087] FIG. 28 shows a further embodiment of a port fitting, indicated generally by reference 224, that is similar to port fitting 182 except that it is a banjo-type fitting adapted for use at the end of a manifold tube 12,14. In such configuration, an opening 208 for receiving the tube manifold 12 or 14 is only provided at an one end plate (plate 204 in the FIG. 28), and the other end plate (end plate 206 in FIG. 28) is sealed and acts as a stop for engaging an end of the manifold tube 12,14. In banjo-type fitting, openings 22 could be spaced apart from the end of the manifold tube as shown in FIG. 28, or could be notches formed about the radius of the bottom of the tube.

[0088] In some embodiments where the fitting 182 is to be used between two adjacent flat tube elements 16 that each encircle the manifold tubes, integral top plates 204 and 206 may be omitted from the collar 200, and functionally replaced by the facing surfaces of the two adjacent flat tube elements 16.

[0089] In some embodiments, the collar 200 and passage 212 may extend only partially around the manifold tube. In some embodiments, the collar 200 could be secured in place prior to brazing by radial expansion of the manifold tube. In some embodiments, the collar could be formed from a non-metal such as a polymer material and secured by epoxy or other adhesive. It will be appreciated that the collar fitting and manifold tube combination of FIGS. 26 and 27 could be used in heat exchangers having a variety of different configurations, including for example conventional stacked plate exchangers in which the plate ends are received within the manifold tubes.

[0090] The flat tube elements 16 have been described as comprising two separate opposing plates 18, 20 that are joined together by brazing along their respective edges. It will be appreciated that flat tube elements in which the opposing plates are formed in another manner can be used in the present invention. By way of example, FIGS. 29 and 30 illustrate partial sectional perspective views of two further flat tube elements 16A and 16B, respectively, each of which defines a flow channel 21. The first and second plates 18 and 20 of flat tube element 16A are preferably roll formed longitudinally together as a single sheet with longitudinal flanges 252 and 254 provided along opposite side edges thereof. Apertures 48, 50 for the manifold tubes (not shown in FIG. 21) are then pierced through each of the plates 18, 20, and the flange about the apertures extruded, after which the plates 18, 20 are folded together about a common longitudinal edge 250 until the flanges 252 and 254 contact each other. With respect to the flat tube element 16B, in such configuration the edges 256, 258 joining the first and second plates 18, 20 are seamless.

[0091] Although the heat exchanger 10 has been shown in its preferred embodiment as including a flange 64 about the apertures 48, 50 in first and second plates 18, 20, in some applications a flangeless aperture may suffice, in which case a somewhat weaker butt joint rather than an overlap joint would be formed between the plates 18, 20 and each of the manifold tubes 12, 14. Furthermore, in some embodiments, the annular flow path 23 may not be present about the entire circumference of the manifold tubes.

[0092] The heat exchangers of the present invention as described above have each included corrugated fins 24 located between adjacent flat tube elements 16. In some embodiments, such fins may be omitted, or replaced with ribs or other protrusions formed on the flat tube elements 16. In embodiments where the fins are omitted, spacing between the adjacent flat tube elements 16 may be provided by enlarged bosses around the apertures, such as the enlarged annular area 110 as shown in FIG. 15. In some fin-less embodiments, removable spacers may be positioned between adjacent tube elements 16 to support them during assembly.

[0093] Another embodiment of a heat exchanger according to the present invention is shown in a simplified view indicated by reference number 270 in FIG. 31. The heat exchanger 270 is similar in construction and operation to the heat exchanger 10 as described above except for the differences noted below. In heat exchanger 10, the manifold tubes 21 and 14 are connected by a bypass tube 272 through which fluid can flow directly from one manifold tube to the other, bypassing the core stack 108. A calibrated baffle 274 or other flow control means such as a thermostatically actuated valve can be located in the bypass tube 272 to control flow therethrough. The tubes 12, 14, and 272 may be integrally formed as a single U-shaped unit.

[0094] In some embodiments, only a single expanded manifold tube may be used, with the second manifold having a different configuration, such as, for example, the cup configuration shown in U.S. Pat. No. 5,634,518 issued Jun. 3, 1997.

[0095] The above description has anticipated that the heat exchanger components are made out of metal. However, other materials such as plastics or other polymers could be used in some applications for all or some of the heat exchanger components. In a polymer embodiment, manifold tubes may be thermally expanded rather than or in addition to being pressure expanded. Alternatively, the manifold tube may not be expanded, but a friction fit between the flat plate tube element and the manifold tubes used in combination with bonding effected, for example, thermally, ultrasonically, or through the use a bonding agent or adhesive.

[0096] The heat exchanger of the present invention can be adapted for a number of different applications for use, among other things, in automobiles, recreational vehicles, and fuel cell thermal management systems. In addition to the transmission oil and power steering fluid cooling applications mentioned above in respect of heat exchanger 10, the present invention can be adapted for use in, among other things, engine oil cooling, hydraulic fluid cooling (which requires high pressure strength) and air conditioning applications (for both evaporator and condenser applications). Selective variable manifold tube slot size and positioning can be particularly helpful in evaporator applications where flow distribution sensitivity is high.

[0097] It will also be apparent to those skilled in the art that in light of the foregoing disclosure, many other alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined in the following claims.

Claims

1. A heat exchanger comprising:

a manifold tube having a wall defining a flow passage therethrough and having a plurality of longitudinally spaced apart openings formed through the wall in flow communication with the flow passageway; and

a plurality of flat tube elements located along a longitudinal axis of the manifold tube, each including a first plate and a second plate defining a flow channel therebetween, the plates each being provided with an aperture therethrough, the apertures in the first and second plates of each of the tube elements being substantially in alignment with each other, the manifold tube being received through the apertures in the first and second plates of each of the flat tube elements with each of the spaced apart openings in flow communication with the flow channel of a respective one of the flat tube elements;

the wall of the manifold tube and the apertures being respectively sized that an outer surface of the manifold tube engages an inner surface surrounding the aperture in each of the first and second plates to secure the flat tube elements to the manifold tube, the flat tube elements being supported by the manifold tube.

2. The heat exchanger of claim 1 wherein the manifold tube is radially expanded at least along portions thereof where the outer surface engages the first and second plates of the flat tube elements.

3. The heat exchanger according to claim 1 wherein the inner surface of the aperture in the first and second plates that is engaged by the wall of the manifold tube is defined by an integral peripheral flange extending outward from the plate such that an overlap joint is formed between the wall and the peripheral flange, and the wall is brazed to the peripheral flange of each of the plates to seal a juncture therebetween.

4. The heat exchanger according to claim 1 wherein the first and second plates each have a substantially planar elongate central portion surrounded by a planar edge portion inwardly offset from and parallel to the planar central portion, the first and second plates of each flat tube element being joined together with the planar central portions spaced apart from each other to define the flow channel and the offset edge portion of the first plate abutting against the offset edge portion of the second plate.

5. The heat exchanger or claim 1 wherein, in at least some of the flat tube elements, the first plates and second plates are identical to each other.

6. The heat exchanger according to claim 1 wherein the flat tube elements are spaced apart from each other defining lateral passageways therebetween, and including fins located in the lateral passageways and in thermal contact with the flat tube elements.

7. The heat exchanger of claim 1 wherein the spaced apart openings include openings of more than one size.

8. The heat exchanger of claim 1 wherein the spaced apart openings are progressively larger along a length of the manifold tube.

9. The heat exchanger of claim 1 including at least one flat tube element having a flow channel that is in flow communication with the flow passage of the manifold tube through a plurality of radially spaced openings formed through the manifold tube wall.

10. The heat exchanger of claim 1 wherein the flat tube elements are spaced apart from each other and the spacing distance between the flat tube elements varies along the manifold tube.

11. The heat exchanger of claim 1 wherein the flow passage through the manifold tube is divided into first and second flow chambers with some of the flat tube elements being in flow communication with the first chamber and others of the flat tube elements being in flow communication with the second flow chamber.

12. The heat exchanger of claim 11 wherein a baffle cup located within the manifold tube divides the manifold tube into the first and second flow chambers, the baffle cup having a cylindrical wall having an outer surface in engagement with an inner surface of the manifold tube wall.

13. The heat exchanger of claim 12 wherein an error proofing opening is provided through the manifold tube wall at a location where the wall of the baffle cup overlaps the manifold tube wall, the error proofing opening being sized to permit visual confirmation of the presence of the wall of the baffle cup.

14. The heat exchanger of claim 1 including a mounting bracket having a collar engaging the manifold tube between two adjacent flat tube elements.

15. The heat exchanger of claim 1 wherein at least some of the flat tube elements include first and second plates having portions that are spaced further apart from each other closer to the manifold tube than further from the manifold tube to define a higher flow channel, relative to the longitudinal axis of the manifold tube, nearer the manifold tube than further from the manifold tube.

16. The heat exchanger of claim 1 including a port fixture mounted to the manifold tube, the port fixture defining a flow passageway that is in flow communication, through a port opening in the manifold, with the flow passage through the manifold tube, the port fixture including a collar surrounding an annular area of the manifold tube.

17. The heat exchanger of claim 16 wherein the collar of the port fixture defines an annular fluid flow way about the annular area of the manifold tube, the annular area having a plurality of radially spaced openings through which the annular fluid flow way is in flow communication with the flow passage through the manifold tube.

18. The heat exchanger of claim 17 wherein the collar is located between two adjacent flat tube elements.

19. The heat exchanger of claim 17 wherein the port fixture is a banjo-type fitting and the collar engages an end of the manifold tube.

20. The heat exchanger of claim 1 wherein the outer surface of the manifold tube engages substantially an entire circumference of the inner surface of the aperture in each of the plates in a butt-joint fashion.

21. The heat exchanger of claim 1 including a further manifold tube having a wall defining a flow passage therethrough and having a plurality of spaced apart openings formed through the wall in flow communication with the flow passageway, each of the plurality of first and second plates being provided with a further aperture therethrough, the manifold tube being received through the further apertures in the first and second plates of each of the flat tube elements with each of the spaced apart openings through the further manifold tube in flow communication with the flow channel of a respective one of the flat tube elements, the wall of the further manifold tube and the further apertures being respectively sized that an outer surface of the further manifold tube engages an inner surface surrounding the further aperture in each of the first and second plates to secure the flat tube elements to the further manifold tube, the flat tube elements being supported by the manifold tube and the further manifold tube;

the heat exchanger further including a inlet port in flow communication with the flow passage through the manifold tube, and an outlet port in flow communication with the flow passage through the further manifold tube.

22. The heat exchanger of claim 21 wherein the manifold openings though the manifold tube and the further manifold tube are inwardly oriented towards each other.

23. The heat exchanger of claim 21 wherein the manifold openings through the manifold tube and the further manifold tube are outwardly oriented away from each other.

24. The heat exchanger of claim 21 wherein the manifold tubes are joined together by a bypass manifold tube.

25. The heat exchanger of claim 24 wherein the bypass manifold tube includes fluid flow control means for controlling the flow of fluid therethrough.

26. The heat exchanger of claim 21 further including:

third and fourth elongate spaced-apart manifold tubes each having a wall defining a flow passage therethrough and having a plurality of longitudinally spaced apart manifold openings formed through the wall in flow communication with the flow passageway;

the first and second plates of the flat tube elements each having aligned third and fourth apertures therethrough receiving the third and fourth manifold tubes respectively,

a plurality of further flat tube elements including a first plate and a second plate defining a flow channel therebetween, the plates of the further flat tube elements each being provided with respectively aligned first, second third and fourth apertures therethrough receiving the manifold tube, the further manifold tube and the third and fourth manifold tubes respectively, the flow channel of each of the further flat tube elements being in communication at a first portion thereof with the flow passage of the third manifold tube through a respective one of the manifold openings in the third manifold tube and at a second portion thereof with the flow passage of the fourth manifold tube through a respective one of the manifold openings in the fourth manifold tube;

the wall of the third manifold tube being enlarged at least along portions thereof such that an outer surface of the third manifold tube engages an inner surface surrounding the third aperture in each of the first and second plates of the further flat tube element to secure the further flat tube elements to the third manifold tube, the wall of the fourth manifold tube being enlarged at least along portions thereof such that an outer surface of the fourth manifold tube engages an inner surface surrounding the fourth aperture in each of the first and second plates of the further flat tube element to secure the further flat tube elements to the fourth manifold tube,

the flat tube elements and further flat tube elements being interspersed adjacent each other.

27. The heat exchanger of claim 1 wherein the manifold tubes and flat tube elements are formed from polymers.

28. A method of assembling a stacked plate heat exchanger, comprising:

(a) providing a manifold tube having a wall defining a flow passage therethrough and having a plurality of longitudinally spaced apart openings formed through the wall along a length thereof in flow communication with the flow passageway;

(b) providing a plurality of flat tube elements each including a first plate and a second plate defining a flow channel therebetween, the plates each being provided with an aperture therethrough, the apertures in the first and second plates of each of the flat tube elements being substantially in alignment with each other;

(c) positioning the-manifold tube-through the apertures in the first and second plates of each of the flat tube elements with each of the spaced apart openings in flow communication with the flow channel of a respective one of the flat tube elements; and

(d) radially expanding at least portions of the manifold tube such that manifold tube engages each of the first and second plates about the apertures thereof to secure the flat tube elements to the manifold tube.

29. The method of claim 28 wherein the flat tube elements are braze clad, and further including, subsequent to expansion step (d), applying heat to the manifold tube and flat tube elements to seal a joint between each of the first and second plates and the manifold tube.

30. The method of claim 28 wherein step (b) includes providing an integral peripheral flange around the apertures of the first and second plates, the peripheral flange of each aperture defining a circumference that is engaged by the radially expanded manifold tube.

31. The method of claim 28 wherein the manifold tube is radially expanded substantially uniformly along substantially an entire length thereof.

32. The method of claim 28 wherein the manifold tube is selectively radially expanded in a vicinity of each of the flat tube elements.

33. The method of claim 28 wherein the manifold tube is radially expanded using a hydraulic bladder.

34. The method of claim 28 including providing fins between and in thermal contact with adjacent flat tube elements.

35. The method of claim 34 including assembling a core stack by aligning stacked alternating flat tube elements and fins to a desired height with the apertures in alignment and subsequently inserting the manifold tube through the aligned apertures.

36. The method of claim 34 including assembling a core stack by building up flat tube elements on the manifold tube.

37. The method of claim 34 including compressing a core stack comprising the flat tube elements and the fins prior to radially expanding the manifold tube.

38. The method of claim 28 wherein said step (b) of providing a plurality of flat tube elements includes roll forming substantially identical first and second plates each with a central planer portion having longitudinal edge flanges provided along both longitudinal side edges thereof for joining the first and second plates together; cutting the roll formed first and second plates at a desired length and forming ends thereon, and piercing the apertures through the first and second plates.

39. A heat exchanger comprising a manifold tube having a wall defining a fluid flow passage therethrough; a stack of flat tube elements connected to the manifold tube and each having a flow channel therethrough in fluid communication with the fluid flow passage; and a baffle cup having a wall engaging an inner surface of the manifold tube wall, the manifold tube wall having an error proofing hole formed therethrough at a location where the baffle cup wall is positioned, the hole being sized such that a visual check can be performed to ensure that the baffle cup is in place, the error proofing hole being sealably covered by the wall of the baffle cup.

40. A heat exchanger comprising a manifold tube having a wall defining a fluid flow passage therethrough; a stack of flat tube elements connected to the manifold tube and each having a flow channel therethrough in flow communication with the fluid flow passage; and a port fixture having a collar providing a flow way surrounding at least a portion of the manifold tube wall having a plurality of spaced openings formed therethrough, the flow way being in flow communication with the fluid flow passage through the spaced openings, the port fixture having a connecting member extending from the collar and defining a fluid passageway in flow communication with the flow way.

41. The heat exchanger according to claim 40 wherein the collar includes an annular wall having a first end wall formed at one end thereof and a second end wall formed at an opposite end thereof, the first and second end walls each having an opening therethrough through which the manifold tube passes, the annular wall and first and second end walls defining the flow way.

42. The heat exchanger according to claim 40 wherein the port fixture is a banjo-type fitting, and the collar includes an annular wall having a first end wall formed at one end thereof and a second end wall formed at an opposite end thereof, the first end wall having an opening therethrough through which the manifold tube passes, an end of the manifold tube being positioned within the collar, the annular wall and first and second end walls defining the flow way.

43. The heat exchanger according to claim 40 wherein the manifold tube passes internally through openings provided through the flat tube elements and the collar of the port fixture includes an annular wall having a first end that is sealably engaged by an annular portion of one of the flat tube elements surrounding the manifold tube, and a second end that is sealably engaged by an annular portion of a further one of the flat tube elements surrounding the manifold tube, the annular wall and said annular portions defining the flow way.