Continuous combination fin for a heat exchanger

Abstract: A continuous combination fin (22) for a heat exchanger (10) includes a base wall (24) having a first portion (26), a second portion (28) and a third portion (30) . The continuous combination fin (22) also includes a plurality of entrance louvers (32) in the first portion (26) extending outwardly at a predetermined angle in a first direction from the base wall (24). The continuous combination fin (22) includes a plurality of exit louvers (36) in the third portion (30) extending outwardly at a predetermined angle in a second direction from the base wall (24) reversed from the first direction. The continuous combination fin (22) further includes a plurality of drainage louvers (40) in one of the first portion (26) and the second portion (28) and the third portion (30) that are off-set relative to each other such that air flows through the entrance louvers (32) and exit louvers (36) and water drains through the drainage louvers (40).

Description: The present invention relates generally to heat exchangers for motor vehicles and, more specifically, to a continuous combination fin for a heat exchanger in a motor vehicle. It is known to provide a louvered fin for a heat exchanger such as an evaporator in a motor vehicle. An example of such a louvered fin is disclosed in U.S. Patent No. 5,738,168. The louvered fin typically is a corrugated fin having generally planar walls joined in a 'V' shape at crests. The louvered fin also has a plurality of louvers bent integrally out of the walls at an angle for the purpose of breaking up airflow over the fins and increasing heat transfer. Further, the louvered fin may have multiple louvers in which the louvers are divided into a pattern of alternating, adjacent sets of louvers to guide airflow in an attempt to induce turbulent flow therein. Commonly, two sets of louvers are used, an entrance set and an exit set separated from one another by a central portion. When air flows over the walls of the louvered fin, the airflow will engage the louvers of the entrance set and be deflected upwardly through the wall at the angle of the entrance set of louvers. Air in the deflected stream flows between a pair of adjacent central portions in two adjacent walls. The air is deflected back through the louvers of the exits set in the same way. It should be appreciated that the airflow has a generally shallow bell curve shape. Another known louvered fin for a heat exchanger such as an evaporator is disclosed in U.S. Patent No. 4,580,624. In this patent, groups of louvers are sloped alternately or in different combinations on the fin. It is also known to provide an off-set strip fin for a heat exchanger. An example of such a fin is disclosed in U.S. Patent No. 4,615,384. In this patent, the off-set strip fin has a wall with plurality of louvers separated by a fixed distance from the wall. The louvers are staggered, i. e. arranged alternately on an upper side and a lower side of the wall, so that each pair of louvers adjacent to each other give rise to an empty space for water discharge. Other examples of known fins for heat exchangers are disclosed in U.S. Patent No. 3,214,954 and Japanese Patent No. 10-141805. U.S. Patent No. 3,214,954 discloses a fin roll and Japanese Patent No. 10-141805 discloses a multistage fin. Although the above fins have worked for an evaporator, the louvered fin outperforms the off-set strip fin in heat transfer. On the other hand, the off-set strip fin outperforms the louvered fin in water shedding. Also, the turnaround rib is the weakest heat transfer area of the louvered fin. Therefore, there is a need in the art to provide a continuous combination fin for a heat exchanger that outperforms conventional fins in both heat transfer and water shedding. JP-58217195 discloses a fin which has two sets of louvers separated by a water discharge feature which allows condensed water to be discharged. According to the invention, there is provided a continuous combination fin for a heat exchanger comprising a base wall having a first portion, a second portion and a third portion, a plurality of entrance louvers and a plurality of first apertures in said first portion, the louvers extending outwardly at a predetermined angle in a first direction from the base wall, extending generally perpendicular to a longitudinal axis of the base wall and being spaced longitudinally therealong and the first apertures being disposed between a pair of adjacent entrance louvers, a plurality of exit louvers and a plurality of second apertures in said third portion, the louvers extending outwardly at a predetermined angle in a second direction from the base wall reversed from the first direction, extending generally perpendicular to the longitudinal axis of the base wall and spaced longitudinally therealong, and the second apertures being disposed between a pair of adjacent exit louvers, and a plurality of drainage louvers, characterized in that the drainage louvers extend in the second portion generally perpendicular to the longitudinal axis of the base wall, are spaced longitudinally therealong and are off-set vertically from the base wall a distance therefrom, to form drainage apertures intermediate the first and third portions and disposed below the drainage louvers such that air flows through the entrance louvers, through the drainage louvers and through the exit louvers and water drains through the drainage apertures. The invention will now be further described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an elevational view of a continuous combination fin, according to the present invention, illustrated in operational relationship with a heat exchanger. Figure 2 is an enlarged perspective view of the continuous combination fin of Figure 1. Figure 3 is an elevational view of the continuous combination fin of Figure 1. Figure 4 is a sectional view taken along line 4-4 of Figure 3. Figure 5 is a view similar to Figure 4 of another embodiment, according to the present invention of the continuous combination fin of Figure 1. Figure 6 is a view similar to Figure 4 of yet another embodiment, according to the present invention of the continuous combination fin of Figure 1. Figure 7 is a view similar to Figure 4 of still another embodiment, according to the present invention of the continuous combination fin of Figure 1. Figure 8 is a view similar to Figure 4 of a further embodiment, according to the present invention of the continuous combination fin of Figure 1. Figure 9 is a view similar to Figure 4 of a continuous combination fin. Figure 10 is a view similar to Figure 4 of a still further embodiment, according to the present invention of the continuous combination fin of Figure 1. Figure 11 is a graph of transient water retention for the continuous combination fin of Figure 5 versus a baseline fin. Figure 12 is a graph of evaporator performance comparison for the continuous combination fin of Figures 7 through 10. DESCRIPTION OF THE PREFERRED EMBODIMENT(S) Referring to the drawings and in particular Figure 1, one embodiment of a heat exchanger 10, such as an evaporator, is shown for a motor vehicle (not shown). The heat exchanger 10 includes a plurality of generally parallel and U-shaped plates or tubes 12 and a header 14 connected to one end of the tubes 12. The heat exchanger 10 includes a fluid inlet 16 for conducting cooling fluid into the heat exchanger 10 formed in the header 14 and an outlet 18 for directing fluid out of the heat exchanger 10 formed in the header 14. The heat exchanger 10 also includes a plurality of convoluted or serpentine continuous combination fins, generally indicated at 22 and according to the present invention, attached an exterior of each of the tubes 12. The continuous combination fins 22 are disposed between each of the tubes 12. The continuous combination fins 22 serve as a means for conducting heat away from the tubes 12 while providing additional surface area for convective heat transfer by air flowing over the heat exchanger 10. It should be appreciated that, except for the continuous combination fins 22, the heat exchanger 10 is conventional and known in the art. It should also be appreciated that the continuous combination fins 22 could be used for heat exchangers in other applications besides motor vehicles. Referring to Figures 2 through 4, the continuous combination fin 22 includes at least one, preferably a plurality of base walls 24 joined to one another in generally 'V' shaped corrugations. Each base wall 24 is generally planar and rectangular shape. Each base wall 24 extends longitudinally to form a first portion 26, second portion 28 and third portion 30. The base wall 24 is made of a metal material such as aluminum or an alloy thereof. The continuous combination fin 22 also includes a plurality of first or entrance louvers 32 in the first portion 26 extending outwardly at a relatively large or predetermined louver angle such as forty-three degrees (43°) in a first direction from the base wall 24. The entrance louvers 32 are generally planar and rectangular in shape. The entrance louvers 32 extend laterally or generally perpendicular to a longitudinal axis of the base wall 24. The entrance louvers 32 are pierced and bent out of the base wall 24 to form apertures 34 for air to flow therebetween. The entrance louvers 32 are spaced longitudinally at a relatively small or predetermined louver pitch such as 0.8 millimeters (mm) to 1.0 mm to enhance heat transfer. The continuous combination fin 22 includes a plurality of second or exit louvers 36 in the third portion 30 extending outwardly at a relatively large or predetermined louver angle such as forty-three degrees (43°) in a second direction reversed from or opposite the first direction. The exit louvers 36 are generally planar and rectangular in shape. The exit louvers 36 extend laterally or generally perpendicular to the longitudinal axis of the base wall 24. The exit louvers 36 are pierced and bent out of the base wall 24 to form apertures 38 for air to flow therebetween. The exit louvers 36 are spaced longitudinally at a relatively small or predetermined louver pitch such as 0.8 millimeters (mm) to 1.0 mm to enhance heat transfer. It should be appreciated that the louvers 32 and 36 enhance heat transfer performance. The continuous combination fin 22 further includes a plurality of third or drainage louvers 40 in the second portion 28 extending outwardly and generally parallel to the base wall 24. The drainage louvers 40 are generally planar and rectangular in shape. The drainage louvers 40 extend laterally or generally perpendicular to the longitudinal axis of the base wall 24. The drainage louvers 40 are pierced and off-set out of the base wall 24 a distance therefrom to form apertures 42 for fluid such as water to drain therebetween. The drainage louvers 40 may be staggered or arranged alternately on both sides of the base wall 24. It should be appreciated that the drainage louvers 40 are off-set relative to each other. It should also be appreciated that the off-set drainage louvers 40 enhance water shedding/drainage. The continuous combination fin 22 includes a central turnaround rib 44 in the second portion 28 between a first set of drainage louvers 40 adjacent the entrance louvers 32 and a second set of drainage louvers 36 adjacent the exit louvers 36. The continuous combination fin 22 is formed as a monolithic structure being integral, unitary and one-piece. In operation of the continuous combination fin 22, air flows between the base walls 24 as indicated by the arrows in Figure 4. The air engages the entrance louvers 32 and is deflected through the apertures 34 in the first portion 26 of the base wall 24. The deflected air is impacted by air flowing straight between the base walls 24. The air flows generally parallel between a pair of second portions 28 in two adjacent base walls 24. The air flows past the drainage louvers 40 and the turn-around rib 44 where heat transfer is the weakest and water in the air condenses such that the condensed water drains through the apertures 42 in the second portion 28 of the base wall 24. The air engages the exit louvers 36 and is deflected through the apertures 38 in the third portion 30 of the base wall 24. It should be appreciated that the airflow has a shape similar to a shallow flat bell curve. Referring to Figure 5, another embodiment, according to the present invention, of the continuous combination fin 10 is shown. Like parts of the continuous combination fin 10 have like reference numerals increased by one hundred (100). In this embodiment, the continuous combination fin 110 has the drainage louvers 140 formed from the base wall 124 disposed above and below a plane of the base wall 124. It should be appreciated that the continuous combination fin 110 is symmetrical about a centerline C. Referring to Figure 6, yet another embodiment, according to the present invention, of the continuous combination fin 10 is shown. Like parts of the continuous combination fin 10 have like reference numerals increased by two hundred (200). In this embodiment, the continuous combination fin 210 has the drainage louvers 240 disposed above and below the base wall 224 with portions of the base wall 224 therebetween. It should be appreciated that the continuous combination fin 210 is symmetrical about a centerline C. Referring to Figure 7, still another embodiment, according to the present invention, of the continuous combination fin 10 is shown. Like parts of the continuous combination fin 10 have like reference numerals increased by three hundred (300). In this embodiment, the continuous combination fin 310 has exit louvers 336 disposed between the entrance louvers 332 and the drainage louvers 340. The drainage louvers 340 are disposed above and below the base wall 324 with portions of the base wall 324 therebetween. It should be appreciated that the continuous combination fin 310 is symmetrical about a centerline C. Referring to Figure 8, a further embodiment, according to the present invention, of the continuous combination fin 10 is shown. Like parts of the continuous combination fin 10 have like reference numerals increased by four hundred (100). In this embodiment, the continuous combination fin 410 has the drainage louvers 440 formed from the base wall 424 disposed above and below a plane of the base wall 424. It should be appreciated that the continuous combination fin 410 is symmetrical about a centerline C. Referring to Figure 9, like parts of the continuous combination fin 10 have like reference numerals increased by five hundred (500). The continuous combination fin 510 has a first plurality of drainage louvers 540 separated by a generally V-shaped divider 550 by a second plurality of drainage louvers 540'. The drainage louvers 540 and 540' are disposed above and below the base wall 524 with portions of the base wall 524 therebetween. The drainage louvers 540 and 540' are disposed before the entrance louvers 532 and after the exit louvers (not shown). It should be appreciated the continuous combination fin 510 is symmetrical about a centerline C. Referring to Figure 10, a still further embodiment, according to the present invention, of the continuous combination fin 10 is shown. Like parts of the continuous combination fin 10 have like reference numerals increased by six hundred (600). In this embodiment, the continuous combination fin 610 has the drainage louvers 640 formed from the base wall 624 disposed above and below a plane of the base wall 624. The drainage louvers 640 extend longitudinally a distance greater than a distance of the entrance louvers 632. It should be appreciated that the continuous combination fin 610 is symmetrical about a centerline C. Referring to Figure 11, a graph 700 of transient water retention for the continuous combination fin 110 of Figure 5 is shown. The graph 700 has time (in seconds) on an x-axis 710 and water retained (in grams) on a y-axis 720. The graph 700 has a curve 730 of transient water retention (no airflow) for a baseline fin (not shown), which is a conventional louvered fin and a curve 740 of transient water retention of the continuous combination fin 110. As illustrated, the continuous combination fin 110 retains less water over time than the baseline fin. Referring to Figure 12, a graph 800 of evaporator performance comparison for the continuous combination fins 210, 310, and 410 is shown. The graph 800 has fin configurations 210, 310 and 410 on an x-axis 810 and percent improvement on a y-axis 820. The evaporator performance comparison was carried out using a calorimeter test at 250 cfm for the continuous combination fins versus conventional louvered fins. As illustrated, the continuous combination fin 410 performed the best while all continuous combination fins 210,310,410 performed better than conventional louvered fins. The present invention has been described in an illustrative manner. It is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations are possible in light of the above teachings. Therefore, within the scope of the appended claims, the present invention may be practiced other than as specifically described. An advantage of the present invention is that the continuous combination fin provides two types of louvers to obtain the best performance of both the louvered fin and off-set strip fin. Still another advantage of the present invention is that the continuous combination fin provides a relatively large louver angle and a relatively small louver pitch. A further advantage of the present invention is that the continuous combination fin provides a flexible fin roll that can have a family of three or more different combinations.

Claims: A continuous combination fin for a heat exchanger comprising a base wall (24) having a first portion (26), a second portion (28) and a third portion (30), a plurality of entrance louvers (32) and a plurality of first apertures (34) in said first portion (26), the louvers extending outwardly at a predetermined angle in a first direction from the base wall (24), extending generally perpendicular to a longitudinal axis of the base wall and being spaced longitudinally therealong and the first apertures being disposed between a pair of adjacent entrance louvers, a plurality of exit louvers (36) and a plurality of second apertures (38) in said third portion (30), the louvers extending outwardly at a predetermined angle in a second direction from the base wall (24) reversed from the first direction, extending generally perpendicular to the longitudinal axis of the base wall and spaced longitudinally therealong, and the second apertures being disposed between a pair of adjacent exit louvers, and a plurality of drainage louvers (40), characterized in that the drainage louvers (40) extend in the second portion generally perpendicular to the longitudinal axis of the base wall (24), are spaced longitudinally therealong and are off-set vertically from the base wall a distance therefrom, to form drainage apertures (42) intermediate the first and third portions and disposed below the drainage louvers (40) such that air flows through the entrance louvers (34), through the drainage louvers and through the exit louvers (36) and water drains through the drainage apertures (42). A continuous combination fin as claimed in Claim 1, wherein said base wall (24) is generally planar and rectangular in shape. A continuous combination fin as claimed in Claim 1 or Claim 2, wherein each of the entrance louvers (32) is formed from the base wall at said predetermined angle to form said first apertures (34). A continuous combination fin as claimed in any preceding claim wherein each of the exit louvers (36) are formed from the base wall (24) at said predetermined angle to form said second apertures (38). A continuous combination fin as claimed in any preceding claim, including a plurality of base walls (24) joined to one another in generally V shaped corrugations. A continuous combination fin as claimed in any preceding claim, wherein the base wall (24), the entrance louvers (32), the exit louvers (36) and the drainage louvers (40) are integral, unitary and formed as one-piece. A continuous combination fin as claimed in any preceding claim, wherein the base wall is made of a metal material.

Inventors: ABDULNOUR RAMEZ S, HU SHYR-ING, MEHRABAN HENRY, ZHANG CHAO ABRAHAM, ABDULNOUR, RAMEZ S., HU, SHYR-ING, MEHRABAN, HENRY, ZHANG, CHAO ABRAHAM
Applicants: VISTEON GLOBAL TECH INC, VISTEON GLOBAL TECHNOLOGIES, INC.
Application year: 2000
Main classification: F28F1
IPC codes: F25B39, F28F1, F28F3