US20070023171A1

US20070023171A1 - Heat exchanger with separators and improved strength

Info

Publication number: US20070023171A1
Application number: US11/496,260
Authority: US
Inventors: Jay Lorentz; Seung-Kwan Chon; Thierry Camus
Original assignee: Valeo Inc
Current assignee: Valeo Inc
Priority date: 2005-07-29
Filing date: 2006-07-31
Publication date: 2007-02-01

Abstract

A heat exchanger with improved strength is provided. Strength improvement features on the heat exchanger separators provide for a more robust heat exchanger. Automotive applications, such as radiator and charge air cooler applications, with patterned strength improvement features, such as dimples, elevations, folds, depressions or deformations, or the like, are provided.

Description

This patent application claims priority of Provisional Application No. 60/703,915 filed Jul. 29, 2005

FIELD OF THE INVENTION

The present invention relates to heat exchangers, and, particularly heat exchangers useful in automotive applications.

BACKGROUND OF THE INVENTION

Heat exchangers use fins external to tubes or turbulators (internal to tubes) (collectively sometimes also called separators) as a way to increase surface area and therefore increase heat transfer. Fins have traditionally contained features to either improve heat transfer, e.g. louvers, or features to improve manufacturability, e.g. anti-fin drop embossments. An example of louvers added to a fin to improve heat transfer can be seen on JP8068598. An example of a manufacturing feature of a fin can be seen on JP2001212637.
All of the examples cited above either focus on improving the manufacturability, or improving the heat transfer of the heat exchanger by the use of specific designs.
As cost cutting measures continue on heat exchangers, specifically on automotive heat exchangers with tubes (sometimes referred to a fluid circulation canals), more specifically on automotive brazed tube-fin type heat exchangers, the thickness or “gage” of the metal used to create these fins has been continuously made smaller. Depending upon the thickness and the type of tube, this action may have lowered the strength of the fin to the point where the fin cannot provide proper support in order to survive the manufacturing process.

SUMMARY OF THE INVENTION

Adequate over all heat exchanger strength, and, in particular the contribution of fin strength, has often been an issue in prior art heat exchanger. Particularly in radiator, charge air cooler (CAC) and similar condition applications, the separator, and, especially, fin strength or lack there of, has caused a multitude of problems, particularly with the trend for thinner and thinner fin stock.
The present invention, in one of its aspects, reinforces the mechanical strength of the heat exchanger at or around the surfaces where heat exchange typically occurs. For example, the area of the fin or fins or turbulator or turbulators (fins and turbulators referred to collectively in the present application as ‘separators’) are reinforced to ameliorate the mechanical strength of the heat exchanger without increasing the amount of material at the area of reinforcement.
In various aspects of the present invention, the strength of the separator is increased without increasing material gage, and, therefore, without increasing cost. The preferred embodiments of the present invention, therefore, improve the strength of the separator, allowing for further gage reduction efforts to continue.
By improving the stiffness and strength of the separator through the use of various techniques, such as metal forming techniques, as opposed to adding mass or cross-sectional area to the separator, an improved heat exchanger with fins is provided, without added cost or weight. The present invention, in its various embodiments, provide for separator material or stock, a stock, as appropriate, for, either for production of fins or turbulators, and, particularly a separator stock originally flat or planar in orientation, that will be reinforced or folded to be able to support or resist compressive forces that would not be possible without such reinforcement or folding.
In an aspect of the present invention, folds, deformations, dimples, elevations, depressions, or the like (collectively referred to as strength improvement features) of generally a greater thickness or height than the separator material or stock, preferably of an overall thickness or height of 80 microns or less, or, in particular, fin material itself, in a specific pattern, have been found to increase overall separator, or, in particular, fin or separator strength.
In modern applications, such as folded tube type radiators, much higher compression, often in the order of 10 times higher compression than that needed for welded tube type radiators, is used in production.
In preferred embodiments of the present invention, metal is not added to the separator to improve strength characteristics. The present invention in its preferred embodiments, allows metal forming to improve the strength. By forming the appropriate structures rather than by using additional or added material, lower cost may be achieved while not sacrificing the strength and overall manufacturability of the heat exchanger.
Present invention preferred aspects also can be accomplished with little modification of tools necessary to produce either tubes or fins.
Separators and especially fins made from “separator stock”, often have louvers or thinner areas or even openings in the separator, particularly the fin, for various regions and reasons, including increasing heat exchange. Buy louver it is meant a feature or features on a separator where separator material is cut or punched or pierced or the like and pushed out or otherwise formed to create a surfaces that rises above the surrounding area on the separator to improve heat transfer characteristics. Though such louvers and the like have positive attributes in heat exchangers, as the “separator stock” and eventual gauge is reduced in thickness, such added fin or turbulator modification can lead to an even weaker structure of the fin or turbulator. In a preferred aspect of the present invention, a strength improvement feature, such as a deformation, (especially such as a dimple), is made so that, preferably, it is approximately parallel to the louver, and equal to or greater than the length of the louver measured in the same orientation. Preferably the strength improvement feature starts at the end of the louver and near the radius area of the tube where the fin with louver and tube is assembled in the heat exchanger.
More preferably, the length of the strength improvement feature is the same length or greater than the length of the opening of the louver of the fins.
Dimples, folds or deformations or the like, for example, in other aspects may be placed in such a manner as to form a U or V shape in a direction along the length of the separator stock used to make, a separator, as, for example, in FIG. 4 or 5. Though the U or V shape appears to be of different alignment in various angles, in various aspects of the present invention, the point or apex of the dimple is aligned so that the dimple is basically symmetrical, i.e. such that the dimple has segments or arms, appropriately of equal characteristics, on both sides of the point or apex.
The presence of the deformation or dimple or fold or the like increases the strength of the separator. Aspects of the present invention are applicable on brazed or non-brazed radiators.
The distribution of dimples increases the strength and/or rigidity of the fin or turbulator, even in cases where a loss of rigidity would normally occur due to use of thinner material fin or turbulator stock. Aspects of the present invention, where n is the number of rows of tubes, there are at least n strengthening features, and, preferably, 2n or 2n+1 or 2n−1 strength improvement features in each individual separator as viewed in cross section (for example, in FIG. 11) through a plurality of fins, to provide increased strength for fin and turbulators for heat exchangers.
As a basic example, an orientation of V or U (cap shape) along an axis in series of two or three, preferably a series of three (three zones of deformations, or, especially dimples) provide increased strength for fin and turbulators for heat exchangers, and, especially, radiators, and charge air coolers (CAC). By multiplying the effect by two or three per row of tube, (providing at least 2 or 3 V s or U s dimples per unit) the strength of the unity is increased.
Aspects of the present invention augment the mechanical inertia of the fin or turbulator. In various aspects of the present invention, separator stock is stretched or otherwise distorted to form a material thinner than that of the rest of the fin, i.e. there is a localized area of decreased thickness. This localized area can be folded or plied to form a deformation or dimple, with material thickness in the localized area not thicker than the overall stock material thickness, it protrudes or is elevated at the localized area to provide for a heightened area on the fin or separator which provide increased stress resistance even with decreased fin material thickness. Preferably, the strength improvement feature or features are of a thickness of 80μ or less.
In embodiments wherein the separator stock is produced in one single line, the ‘arms’ or ‘branches’ of the V or U shaped deformations or dimples follow along the axis of the tube. The tube is, therefore, reinforced by the V or U on the modified (dimple reinforced) fin (by in the form of a u or v it is meant that the dimple, fold, deformation or the like have arms or branches off of an apex or highest point, or either side of that apex or higher point).
In aspects of the present invention, a plurality of separators is provided. By separator assembly is meant a plurality of individual separators formed along the length of the separator material. Each individual strengthening feature forms a column, either internal or external to the tube, to provide support for the tube.
The present invention, in its various aspects, may function is various types of exchangers, including single or multiple tubes, single or multiple end tank, single or multi-pass heat exchangers, etc., regardless of the thickness of the area of surface of exchange of the heat exchanger or the size of the area of the heat exchange surface. Also, the present invention, in various aspects, functions regardless of the thickness of the heat exchanger core or other related elements.
The present invention, by providing for a formed surface, without relative increase in amount of material used in the fin or separator, provides for adequate heat exchange properties at the area of heat exchange at or around the fin or separator, particularly in the core of the heat exchanger, while providing for a relatively higher strength of the heat exchanger, and, in particular, the heat exchanger core assembly.
The present invention, in various aspects, can have exchangers with cores with two or more rows of tubes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates an overall view of a tube-fin heat exchanger of the prior art.
FIG. 2 shows a face view of the heat exchanger of FIG. 1.
FIG. 3 is a section view of the heat exchanger of FIG. 1.
FIG. 4 illustrates a face and section view of an embodiment of the present invention illustrating fin design, in accordance with an aspect of the present invention.
FIG. 5 shows a section view of an embodiment of the present invention illustrating a shaped fin design, in accordance with an aspect of the present invention.
FIGS. 6 and 7 illustrate a section view of a prior art fin design.
FIGS. 8, 9 and 10 illustrate a schematic view of an embodiment of the present invention, useful in charge air coolers, illustrating features of fin design, in accordance with an aspect of the present invention.
FIGS. 11 and 12 show a schematic view of an embodiment of the present invention, useful in charge air coolers, illustrating features of fin design, in accordance with an aspect of the present invention.
FIG. 13 is a schematic view of an embodiment of the present invention, useful in charge air coolers, with a core using turbulators and a fin design, in accordance with an aspect of the present invention.

DETAILED DESCRIPTION OF ASPECTS OF THE INVENTION

In various aspects of the present invention, a strengthened heat exchanger without the addition of increased material that increases weight and or has manufacturability issue is provided. A mechanically strengthened heat exchanger means that the heat exchanger can withstand increase pressure conditions in spite of relatively thinner fins or separators due to the fact that the formed fins or separators provide additional mechanical support. An increased number of thermal or pressure cycles, for example, could be supported in testing of a radiator comprising a strength improvement feature comprising a modification or formation of a fin or turbulator (“separator”) in accordance with an aspect of the present invention. Thermic performance and air distribution conditions are conserved, while ameliorating overall strength of the heat exchanger.
In various aspects of the present invention, a heat exchanger having at least one tube; at least one tank; at least one row of tubes; at least one separator formed from an uniform thickness separator stock; and at least one strength improvement feature on the at least one separator, is provided. The mechanical strength of the heat exchanger in these aspects is reinforced.
In aspects of the present invention, at least one louver and at least one strength improvement feature on the separator are provided. In other aspects of the present invention, separators having a plurality of strength improvement features are provided, the strength improvement features having a thickness of less than or equal to 80 microns.
In various aspects of the present invention, the strength improvement feature is a dimple, elevation, fold, depression or deformation, or the like. In various embodiments, the strength improvement feature is a dimple, elevation, fold, depression, deformation or the like, and is in the form of a U or V, and wherein the strength improvement feature has a point or apex. Also, in various embodiments, the dimple, elevation, fold, depression, deformation or the like is formed from material of a thickness less than that of the separator stock. Also, the dimple, fold, deformation or the like is formed from material of a thickness greater than or equal to that of the separator stock.
As described herein, separators can be turbulators or fins. In various aspects of the present invention, the at least one separator is a fin. Also, in aspects of the invention, having a plurality of fins, the at least one fin has at least one louver. In other aspects, the strength improvement feature is the same or greater in length than the louver of the at least one fin. In aspects of the present invention, the heat exchanger is a radiator having a separator assembly comprising a plurality of separators and at least one strengthening feature on each separator. In various aspects, the radiator is a folded tube type radiator and orientation of the plurality of strength improvement features within a separator assembly align or point in generally the same direction. In aspects of the present invention, wherein a plurality of fins have strength improvement features, the fins can have strength improvement features are located near or at the center of the fin and at the outer edge of the fin to increase resistance to compression. In aspects where the heat exchanger has a plurality of tubes and the separators are situated along a centerline in the plurality of tubes.
Various aspects of the present invention allow for heat exchangers that are oil coolers, condensers, radiators or charge air coolers. The heat exchangers can also be brazed heat exchangers, such as brazed radiators or brazed charge air coolers.
Referring to the Figures is shown a fin design with deformations, and fins. By providing one or more strength improvement features in a hereinafter called separators assembly, separator can be aligned or point in generally the same direction, for example like a column and strength and support of heat exchanger core tubes, such as radiator tubes, is achieved. The entire heat exchanger is, therefore, strengthened or thereby made more solid or resistant. In various examples, tubes are strengthened by fold in fin or turbulator in specific area. Folds can be single, U or V shaped, in series multiple, and/or have alternating areas of deformations, folds or dimples, in various aspects of the present invention.
Referring to FIG. 1 is shown an overall view of a prior art heat exchanger having at least one tube (2), tank (1) and at least one fin (3). Also shown are headers (4).
Referring to FIGS. 2 and 3 are shown are cross sections of part of a heat exchanger core with fins (23,33) that have louvers (24, 34) added to improve heat transfer. Tube (22) adjacent to fin (23) are also shown.
Referring to FIG. 4 is shown a cross section view of part of the heat exchanger, in particular the part of the core comprising tube (42) and separator which is a fin (43). Strength improvement feature (46) is a dimple on fin, with additional strength improvement feature (45) added in the center of the fin in accordance with an aspect of the present invention. Strength improvement feature, at the outer edge of the fin (43) increases the stiffness of the fin when in compression.
Referring to FIG. 5, strength improvement features (55, 56) are shown with features 55 a and 55 b in a V and double V (VV, Vv, Vv, etc.) shape respectively. Features 56 a and 56 b show strength improvement features in a U or double U shape.
Referring to FIGS. 6 and 7 is shown schematic views of other aspects and configurations related to the heat exchanger without a strength improvement feature in its design. In FIG. 6, fin (67) and tubes (61, 62) are shown, with axis S-S illustrated and shown in expanded view in FIG. 7. Tube (71) is shown, and fin (77) has louvers (76). Fin axis (FA) and tube axis A-A, are illustrated, with tubes (71, 72).
Referring to FIGS. 8, 9 and 10 is shown arrangements in a heat exchanger of fins symmetrical around centerline (1) in a band of starting material or stock with a specified width or length (2), in accordance with various aspects of the present invention. The symmetry is limited to two zones, (A, B) separated with a V shaped structure or other such structure (88) to separate into two zones. The core has two rows of tubes (91, 92) (101, 102) with fin (107) having a total of three strength improvement features (106), symmetrical around the centerline C and near the axes of tubes (A-A, B-B, C-C).
Referring to FIGS. 11 and 12 is shown, in one of the aspects of the present invention, an exchange surface reinforced mechanically by redistributing the strengtheners in a way to create at least three zones (C, D and E for example). In the example of charge air cooler (CAC) design, the CAC tube air side view is shown with a fin design for a heat exchanger core with separators having N strength improvement features, symmetrical around the axis or centerline of the fin, rather near the axis of N tubes, is illustrated, reinforcing mechanically the exchange surfaces.
The areas formed by the separators can be situated along a centerline (124) in every row of tubes or of fluid circulation canals (115). Specific strength improvement features (112, 113, 114) are shown.
FIG. 12 also illustrate with tubes (T1, T2, T3, T4 . . . TN) and tube axis (T1-T1, T2-T2, T3-T3, T-T 4, . . . T-TN) illustrated. Strength improvement features (126) are shown and the condition of N−1 features (127) is also illustrated when positioned out of line with the axes of the tubes.
Referring to FIG. 13, is shown a turbulator (138) with repeating pattern of segments, which can be characterized as one set of patterns, and the total length being divided up alongside the flank (166) of every tube (fluid circulation canal (135)) fluid. Further, referring to FIG. 13 is shown a heat exchanger related design using turbulators (138), for example, in a charge air cooler. Fin (137) with strength improvement features (136) is located adjacent to tube (135) with turbulator (138) also strengthened at line of feature.
N strength improvement features (136) are added, symmetrical or not around the axis of the turbulator and situated along the side of the tube in order to increase the stiffness of the turbulator when in compression and for better mechanical reinforcement. N varies based on tube length and desired level of rigidity. T side is side of tube.
Unless stated otherwise, dimensions and geometries of the various structures depicted herein are not intended to be restrictive of the invention, and other dimensions or geometries are possible. Plural structural components can be provided by a single integrated structure. Alternatively, a single integrated structure might be divided into separate plural components. In addition, while a feature of the present invention may have been described in the context of only one of the illustrated embodiments, such feature may be combined with one or more other features of other embodiments, for any given application. It will also be appreciated from the above that the fabrication of the unique structures herein and the operation thereof also constitute methods in accordance with the present invention.
The preferred embodiment of the present invention has been disclosed. A person of ordinary skill in the art would realize however, that certain modifications would come within the teachings of this invention. Therefore, the following claims should be studied to determine the true scope and content of the invention.

Claims

1. A heat exchanger for automotive applications having:

at least one tube;

at least one tank;

at least one row of tubes;

at least one separator formed from an uniform thickness separator stock;

at least one strength improvement feature on the at least one separator;

wherein the mechanical strength of the heat exchanger is reinforced.

2. The heat exchanger of claim 1, having at least one louver and at least one strength improvement features on the separator.

3. The heat exchanger of claim 1, having a plurality of strength improvement features, the strength improvement features having a thickness of less than or equal to 80 microns.

4. The heat exchanger of claim 1, wherein the heat exchanger is a radiator having a separator assembly comprising a plurality of separators and at least one strengthening feature on each separator.

5. The heat exchanger of claim 2, wherein the strength improvement feature is a dimple, elevation, fold, depression or deformation, or the like.

6. The heat exchanger of claim 3, wherein the strength improvement feature is a dimple, elevation, fold, depression, deformation or the like, and is in the form of a U or V, and wherein the strength improvement feature has a point or apex.

7. The heat exchanger of claim 3, wherein the at least one separator is a fin.

8. The heat exchanger of claim 4, wherein the radiator is a folded tube type radiator and orientation of the plurality of strength improvement features within a separator assembly align or point in generally the same direction.

9. The heat exchanger of claim 4, wherein the heat exchanger has a plurality of tubes and the separators are situated along a centerline in the plurality of tubes.

10. The heat exchanger of claim 5, wherein the dimple, elevation, fold, depression, deformation or the like is formed from material of a thickness less than that of the separator stock.

11. The heat exchanger of claim 6, wherein the radiator is a folded tube type radiator and orientation of the plurality of strength improvement features within a separator assembly align or point in generally the same direction.

12. The heat exchanger of claim 5, wherein the dimple, fold, deformation or the like is formed from material of a thickness greater than or equal to that of the separator stock.

13. The heat exchanger of claim 7, having a plurality of fins, wherein the at least one fin has at least one louver.

14. The heat exchanger of claim 13, wherein the strength improvement feature is the same or greater in length than the length of the louver of the at least one fin when measured in the same direction as the strength improvement feature.

15. The heat exchanger of claim 3, wherein the separator is a turbulator.

16. The heat exchanger of claim 15, wherein a plurality of fins have strength improvement features, and wherein the fins having strength improvement features are located near or at the center of the fin and at the outer edge of the fin to increase resistance to compression.

17. The heat exchanger of claim 3, wherein the heat exchanger is an oil cooler, condenser, radiator or charge air cooler.

18. The heat exchanger of claim 6, wherein the heat exchanger is an oil cooler, condenser, radiator or charge air cooler.

19. The heat exchanger of claim 14, wherein the heat exchanger is a brazed charge air cooler.

20. The heat exchanger of claim 17, wherein the heat exchanger is a brazed radiator.