TECHNICAL FIELD OF THE INVENTION
The present invention relates to the field of heat exchangers. More specifically, the present invention relates to a fin pack having multiple rows of interconnected fins and a method for producing a heat exchanger having such a fin pack.
BACKGROUND OF THE INVENTION
A heat exchanger is a device which transfers the heat of one substance to another, for example, from a warm or hot surface to a cold or cooler one. Heat exchangers are widely used in industrial processing plants, power plants, air conditioning, vehicles, and the like as evaporators, condensers, and radiators. In a simple form, a heat exchanger includes one or more passages through which a fluid flows while exchanging heat with the environment surrounding the passages.
One typical heat exchanger entails a tube-and-fin type design that includes a number of fluid filled tubes thermally communicating with fins. The fins enhance the ability of the heat exchanger to transfer heat from the fluid in the tubes to the environment, or vice versa. Design variations include the manner in which the fluid passage is constructed and the type of fin used. For example, the passage may be composed of a number of discrete parallel tubes, joined, typically by brazing, to and between a pair of headers. The fins may be provided in the form of panels having apertures through which the tubes are inserted, or in the form of fin rows that can be positioned between adjacent pairs of tubes.
Referring to FIGS. 1-2, FIG. 1 shows a front view of an exemplary prior art tube-and-fin type heat exchanger 20 and FIG. 2 shows a partial perspective view of an exemplary prior art heat exchanger core 22 of heat exchanger 20. Heat exchanger core 22 includes a number of discrete parallel flat core tubes 24 coupled between first and second headers 26 and 28, respectively. Inlet and outlet tubes 30 and 32, respectively, are connected to first and second headers 26 and 28, for the passage of a fluid, such as a refrigerant.
Discrete fin rows 34 are positioned between adjacent pairs of core tubes 24. Each of fin rows 34 is manufactured separately and installed individually between core tubes 24. The separate manufacturing and individual installation increases cycle time and reduces manufacturing efficiency.
Conventionally, a heat exchanger, such as heat exchanger 20, is manufactured by joining tubes 24, fin rows 34, and headers 26 and 28, and other associated components using a brazing operation. Unfortunately, the discrete fin rows 34 can “drop” away from core tubes 24 during the braze cycle. This “drop” is shown in FIG. 2, in which a first row 36 of fin rows 34 is shown as sagging and partially detached from one of core tubes 24 following brazing. In addition, fin rows 34 can be misaligned during assembly causing a short fin-to-header condition (as shown in FIG. 2), fin pitches can be inconsistent, fin rows can lean, and fins can be gapped or separated from core tubes 24.
All of these problems can lead to adverse consequences in terms of both performance and appearance of a heat exchanger. Thus, what is needed is an improved fin row design and improvements in methodology for joining the core tubes and fins of a heat exchanger.
SUMMARY OF THE INVENTION
Accordingly, it is an advantage of the present invention that a fin pack for a heat exchanger is provided that includes multiple rows of interconnected fins.
It is another advantage of the present invention that a fin pack and production method are provided that enable concurrent installation of multiple fin rows with core tubes of a heat exchanger.
Another advantage of the present invention is that a fin pack and heat exchanger production method are provided that result in improved appearance of a heat exchanger, a reduction in dropped and misaligned fins, and a reduction in defective parts.
Yet another advantage of the present invention is that a fin pack and heat exchanger production method are provided that yield efficient manufacture process time.
The above and other advantages of the present invention are carried out in one form by a fin pack for a heat exchanger. The fin pack includes a first row of fins and a second row of fins adjacent to and arranged substantially parallel with the first row of fins. A tabular portion extends between and interconnects the first and second row of fins. The tabular portion defines a channel between the first and second row of fins configured for insertion of a core tube of the heat exchanger.
The above and other advantages of the present invention are carried out in another form by a method of assembling a heat exchanger. The method calls for forming a fin pack having multiple rows of fins, wherein adjacent pairs of the multiple rows of fins are interconnected by tabular portions, the tabular portions defining channels between each of the rows of fins. One each of multiple core tubes are inserted in each of the channels to form a heat exchanger core. Opposing ends of the core tubes of the heat exchanger core are connected to first and second headers, and the heat exchanger core with the first and second headers is brazed to form the heat exchanger.
The above and other advantages of the present invention are carried out in yet another form by a heat exchanger. The heat exchanger includes a first header, a second header, and multiple flat core tubes arranged spaced apart from one another and connected between the first and second headers. The heat exchanger further includes a fin pack having multiple rows of fins and multiple tabular portions such that pairs of adjacent ones of said multiple rows are interconnected by the tabular portions. The tabular portions define channels between each of the rows of fins, the core tubes are seated in the channels, and one each of the rows of fins is disposed between pairs of the core tubes.
BRIEF DESCRIPTION OF THE DRAWINGS
A more complete understanding of the present invention may be derived by referring to the detailed description and claims when considered in connection with the Figures, wherein like reference numbers refer to similar items throughout the Figures, and:
FIG. 1 shows a front view of an exemplary prior art tube-and-fin type heat exchanger;
FIG. 2 shows a partial perspective view of an exemplary prior art heat exchanger core of the heat exchanger of FIG. 1;
FIG. 3 shows a front view of a heat exchanger in accordance with an embodiment of the present invention;
FIG. 4 shows a perspective view of a fin pack for the heat exchanger in accordance with the present invention;
FIG. 5 shows a flowchart of a heat exchanger production process in accordance with another embodiment of the present invention;
FIG. 6 shows a perspective view of a coil of sheet material utilized in connection with fabrication of a fin pack of the heat exchanger of FIG. 3;
FIG. 7 shows a top view of a portion of the sheet material pierced to form slots;
FIG. 8 shows a top view of the sheet material of FIG. 7 with louvers stamped thereon;
FIG. 9 shows a top view of the sheet material with a first fold pattern superimposed thereon;
FIG. 10 shows an end view of the folded sheet material;
FIG. 11 shows a top view of the sheet material with a second fold pattern superimposed thereon;
FIG. 12 shows a front schematic view of core tubes of the heat exchanger being installed in the fin pack; and
FIG. 13 shows a partial front schematic view of core tubes of the heat exchanger installed in a fin pack in accordance with another embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
FIG. 3 shows a front view of a heat exchanger 40 in accordance with an embodiment of the present invention. Heat exchanger 40 includes a heat exchanger core 42 disposed between first and second headers 44 and 46, respectively. Inlet and outlet tubes 48 and 50, respectively, are connected to first and second headers 44 and 46, for the passage of a fluid, such as a refrigerant. Side plates 52 span between first and second headers 44 and 46, respectively, to form an upper and lower boundary of heat exchanger core 42.
Heat exchanger core 42 includes a number of discrete parallel flat core tubes 54 coupled between first and second headers 44 and 46. In accordance with the present invention, heat exchanger core 42 further includes a fin pack 56 having multiple substantially parallel rows 58 of fins 60, with each of rows 58 being corrugated and having a continuous series of fins 60. Adjacent rows 58 of fins 60 are interconnected with first tabular portions 62 shown overlying core tubes 54 and alternating with adjacent rows 58 of fins 60 that are interconnected with second tabular portions 64, shown underlying core tubes 54. Rows 58 are interconnected by first and second tabular portions 62 and 64, respectively, to form a single fin pack 56 of multiple rows 58 of fins 60, as opposed to the discrete fin rows 34 (FIG. 1) of the prior art. As will be discussed in greater detail below, the inclusion of fin pack 56 that includes multiple rows 58 of fins 60 allows for the concurrent installation of multiple rows 58 of fins 60 with multiple core tubes 54, thereby significantly reducing cycle time, increasing manufacturing efficiency, and producing a more consistent product with less manufacturing defects.
It should be noted that core tubes 54 are not typically provided in an actual heat exchanger with cross-hatched markings. Rather, core tubes 54 are shown in FIG. 3 with cross-hatching to more clearly distinguish tubes 54 from first and second tabular portions 62 and 64 that overlie and underlie tubes 54.
FIG. 4 shows a perspective view of a fin pack 56 for heat exchanger 40 (FIG. 3) in accordance with the present invention. Fin pack 56 is shown with several less rows 58, fins 60, first tabular portions 62, and second tabular portions 64 for simplicity of illustration. However, it should be understood that fin pack 56 can have as few as two rows 58 of fins 60, or any number of rows 58 and fins 60 desired for producing heat exchanger core 42 (FIG. 3). In addition, heat exchanger core 42 may be formed from a single fin pack 56, or from several smaller fin packs 56.
Each of fins 60 within rows 58 exhibits an upper edge 66 and a lower edge 68. First pairs 70 of rows 58 are interconnected by first tabular portion 62 at upper edge 66 of each of fins 60. Second pairs 72 (of which only one is shown) of rows 58 are interconnected by second tabular portion 64 at lower edge 68 of each of fins 60. Second pairs 72 of rows 58 alternate with first pairs 70 of rows 58 so that first tabular portions 62 located at upper edge 66 likewise alternate with second tabular portions 64 at lower edge 68.
A length 74 of each of first and second tabular portions 62 and 64, respectively, and a height 76 of fins 60 defines channels 78 between each of rows 58 of fins 60. In a preferred embodiment, height 76 of fins 60 is substantially equivalent to a height 80 of core tubes 54 (one shown in ghost form). Channels 78 extend along an entire length of rows 58. In addition, each of fins 60 includes a substantially flat contact portion 84 that forms an inner wall of one of channels 78. In accordance with the present invention, one each of core tubes 54 is inserted into and largely fills one each of channels 78. In particular, the width of each of channels 78, defined by length 74 of first and second tabular portions 62 and 64 is approximately equivalent to a width 86 of each of core tubes 54, so that flat contact portion 84 of fins 60 abuts an external peripheral wall 88 of each of core tubes 54. This abutment of flat contact portion 84 with wall 88 of each of core tubes 54 can enhance heat transfer efficiency between core tubes 54 and fin pack 56.
Fin pack 56 that includes multiple rows 58 of fins 60 interconnected by first and second tabular portions 62 and 64 yields a rigid and consistent structure, both in appearance and performance. This structure is coupled with core tubes 54, subsequently attached to headers 44 and 46, and can then be brazed as a single unit. Accordingly, improvements are achieved in terms of greater efficiency in manufacture process time and in a reduction in the amount of defective parts and their commensurate waste.
FIG. 5 shows a flowchart of a heat exchanger production process 90 in accordance with another embodiment of the present invention. Process 90 provides generalized methodology of the operations involved in the manufacture of heat exchanger 40 having fin pack 56. In addition, process 90 includes a fin pack fabrication subprocess 92 detailing the operations involved in the manufacture of fin pack 56. The operations described in process 90 may take place in a single manufacturing facility in a serial operation. Alternatively, fin pack fabrication subprocess 92 may occur in a separate facility for producing fin packs 56. Those fin packs 56 may then be assembled into heat exchangers 40 in an assembly facility. Those skilled in the art will recognize that there are other conventional operations pertaining to the manufacture and assembly of heat exchanger 40. These conventional operations are not described herein for brevity.
Heat exchanger production process 90 begins with fin pack fabrication subprocess 92. Referring to FIG. 6, FIG. 6 shows a perspective view of a coil 94 of sheet material 96 utilized in connection with fabrication of fin pack 56 (FIG. 4) of heat exchanger 40 (FIG. 3). Sheet material 96 may be any of a number of materials that are conventionally used to form sheet metal, such as, aluminum, brass, copper, cold rolled steel, mild steel, tin, nickel, titanium, and the like. More particularly, sheet material 96 is formed from those conventional sheet metals that are typically utilized to form fins for heat exchangers.
Referring back to FIG. 5, at an operation 98 of fin pack fabrication method section 92, coil 94 is passed through the appropriate machinery used for unrolling and cutting coil 94 into the appropriate size and shape to produce fin pack 56. In addition, slots are cut into cut sheet material.
Referring now to FIG. 7 in connection with operation 98, FIG. 7 shows a top view of a portion 100 of sheet material 96 cut or pierced to form slots 102. Slots 102 may be formed utilizing conventional sheet metal fabrication equipment such as a punch or a laser. Slots 102 are formed into rows 104 having a first slot pattern 106 alternating with rows 106 having a second slot pattern 108. Each of slots 102 exhibits a base 110 and a side 112, and rows 104 and 106 of slots 102 are arranged with each side 112 parallel to a longitudinal dimension 114 of portion 100 of sheet material 96.
With reference back to FIG. 5, following operation 98 of fin pack fabrication subprocess 92, an operation 116 may be performed. At operation 100, sheet material 96 may optionally be stamped to form louvers. Referring now to FIG. 8 in connection with operation 116, FIG. 8 shows a top view of portion 100 of sheet material 96 with louvers 118 stamped thereon. Heat exchangers, such as heat exchanger 40 (FIG. 3), with louvered fins 60 (FIG. 3) are used widely in the automotive air-conditioning industry. The dominant thermal resistance in compact heat exchangers occurs on the airside, and fins are used to reduce this thermal resistance and improve overall performance of the heat exchanger. Louvers 118 on fins 60 create interrupted surfaces to generate complex airflow patterns that can increase the performance of the heat exchanger.
Referring back to FIG. 5, following operation 116 of fin pack fabrication subprocess 92, an operation 120 may be performed. At operation 120, the sheet material is bent longitudinally to form corrugated fins 60 (FIG. 4) of fin pack 56 (FIG. 4).
Referring to FIGS. 9-10 in connection with operation 120, FIG. 9 shows a top view of portion 100 of sheet material 96 with a first fold pattern 122 superimposed thereon, and FIG. 10 shows an end view of the folded portion 100 of sheet material 96. Portion 100 of sheet material 96 is shown without louvers 118 (FIG. 8) for clarity of illustration.
First fold pattern 122 includes first fold lines 124 having a dash-dot pattern and second fold lines 126 having a dash pattern, as shown in FIG. 9. Sheet material 96 is bent parallel to longitudinal dimension 114 at each of sides 112 of slots 102. Accordingly, first and second fold lines 124 and 126 are aligned and co-located with sides 112 of slots 102.
It should be noted that sheet material 96 is not actually provided with first and second fold lines 124 and 126. Rather, lines 124 and 126 are shown in FIG. 9 to clearly demarcate locations at which sheet material 96 is to be folded and to distinguish a direction of the fold. In this example, first fold lines 124 represent those folds of sheet material 96 that are directed “downwardly,” i.e., into the drawing page. Second fold lines 126 represent those folds of sheet material 96 that are directed “upwardly,” i.e., out of the drawing page.
With the exception of the two outermost first fold lines 124, each of the fold lines occur in alternating pairs of first fold lines 124 and second fold lines 126. Bending portion 100 of sheet material 96 in accordance with first fold pattern 122 yields the continuous series of corrugated fins 60 having flat contact portions 84 that form an inner wall of one of channels 78 (FIG. 4) of fin pack 56 (FIG. 4).
Returning to FIG. 5, following the bending operation of operation 120, fin pack fabrication subprocess 92 continues with an operation 128. At operation 128, sheet material 96 is subsequently bent transversely to form interconnected rows 58 (FIG. 4) of fins 60 (FIG. 4) separated by channels 78 (FIG. 4).
With reference to FIG. 11 in connection with operation 128, FIG. 11 shows a top view of sheet material 96 with a second fold pattern 130 superimposed thereon. It should be noted that FIG. 11 shows portion 100 of sheet material 96 in its flat state, without having first been folded as shown in FIG. 10, in order to clearly distinguish second fold pattern 130. However, in actual practice, sheet material 96 will have first been folded longitudinally in accordance with first fold pattern 122 (FIG. 9), followed by being folded transversely in accordance with second fold pattern 130.
Second fold pattern 130 includes third fold lines 132 having a dash pattern and fourth fold lines 134 having a dash-dot pattern. Sheet material 96 is bent transversely, i.e., perpendicular to longitudinal dimension 114 at each of bases 110 of slots 102. Accordingly, third and fourth fold lines 132 and 134 are aligned and co-located with bases 110 of slots 102.
Again, sheet material 96 need not be provided with third and fourth fold lines 132 and 134. Rather, lines 132 and 134 are shown in FIG. 12 to clearly demarcate locations at which sheet material 96 is to be folded and to distinguish a direction of the fold. In this example, third fold lines 132 can represent those folds of sheet material 96 that are directed “downwardly,” i.e., into the drawing page. Fourth fold lines 134 can represent those folds of sheet material 96 that are directed “upwardly,” i.e., out of the drawing page.
Each of the fold lines occur in alternating pairs of third fold lines 132 and fourth fold lines 134. Bending portion 100 of sheet material 96 in accordance with second fold pattern 130, after sheet material 96 has first been bent in accordance with first fold pattern 122 (FIG. 9) yields the multiple rows 58 (FIG. 4) of fins 60 interconnected by first and second tabular portions 62 and 64, respectively. More specifically, first tabular portions 62 are formed between slots 102 of rows 104 and second tabular portions 64 are formed between slots 102 of rows 106.
Returning to FIG. 5, following the bending operation of operation 128, fabrication of fin pack 56 is complete and fin pack 56 has the appearance of that shown in FIG. 4. Those skilled in the art will recognize that other conventional work processes may be performed such as cleaning and degreasing, applying flux or braze paste, and the like to actually finalize the fabrication of fin pack 56.
Following manufacture of fin pack 56 through the execution of fin pack fabrication subprocess 92, heat exchanger production process 90 continues with a number of operations that describe an efficient process for the assembly of heat exchanger 40 utilizing fin pack 56. Process 90 continues with an operation 136. At operation 136, a subset of core tubes 54 are arranged on a surface.
Referring to FIGS. 5 and 12, FIG. 12 shows a front schematic view of core tubes 54 of heat exchanger 40 (FIG. 3) being installed in fin pack 56. FIG. 12 is not intended to be a realistic portrait of the assembly of core tubes 54 with fin pack 56. Rather, FIG. 12 enables visualization of the concurrent installation of multiple core tubes 54 with fin pack 56. As shown, a subset 138 of, e.g., approximately half, of core tubes 54 utilized with fin pack 56 are arranged on a surface 140. More specifically, core tubes 54 are placed on an edge with a lower side, or width 86, facing surface 140. Surface 140 need not be a substantially flat surface, but may include holding structures and/or placement structures for temporarily retaining core tubes 54 in position.
With continued reference to FIGS. 5 and 12, following operation 136, an operation 142 is performed. At operation 142, fin pack 56 is installed onto subset 138 of core tubes 54 by seating core tubes into those of channels 78 in which first tabular portions 62 are positioned along upper edge 66 between pairs 70 of rows 58 of fins 60. In other words, fin pack 56 is lowered onto subset 138 of core tubes 54, as represented by downwardly directed arrows, labeled “A.”
Next, an operation 144 is performed. At operation 144, a remaining subset 146 of core tubes 54 is inserted into remaining channels 78 having second tabular portion 64 along lower edge 68 between pairs 72 of rows 58 of fins 60 to form heat exchanger core 42 (FIG. 3). Subset 146 of core tubes 54 may be held on edge by a pick and place system, or manipulator, that can hold multiple core tubes 54 and install those multiple core tubes 54 at the same time. In effect, subset 146 of core tubes 54 is lowered onto fin pack 56, as represented by downwardly directed arrows, labeled “B.”
In the instance in which fin pack 56 includes only two rows 58 of fins 60, both of operations 142 and 144 need not occur. Rather, all core tubes 54 may be installed at one time, with either one or more two row fin packs 56 being lowered onto all of the required core tubes 58 or all of core tubes 54 being lowered onto the one or more two row fin packs 56.
Referring back to FIG. 5, following operation 144, an operation 148 is performed. At operation 148, heat exchanger core 42 is connected to first and second headers 44 and 46, respectively (FIG. 3). The alternating connecting tab structure of first and second tabular portions 62 and 64 enables fin pack 56 to lock with core tubes 54 during assembly, thereby eliminating the possibility of dropped fins and providing for better control of fin edges. The connection of heat exchanger core 42 with headers 44 and 46 further locks fin pack and core tubes 54 together resulting in a rigid structure that is subsequently brazed at an operation 150 of process 90. Following operation 150, process 90 exits.
FIG. 13 shows a partial front schematic view of core tubes 54 of heat exchanger 40 (FIG. 3) installed in a fin pack 152 in accordance with another embodiment of the present invention. Fin pack 152 is similar to fin pack 56 and includes multiple rows of a continuous series of corrugated fins 60. Adjacent rows of fins 60 are interconnected along upper edges 66 by first tabular portions 154 alternating with adjacent rows of fins 60 that are interconnected along lower edges 68 by second tabular portions 156 to form a single fin pack 152 of multiple rows of fins.
In accordance with the embodiment shown in FIG. 13, first and second tabular portions 154 and 156 exhibit an outwardly arcuate, or arched, shape 158. Arcuate shape 158 of tabular portions 154 and 156 corresponds with a shape of core tubes 54. That is, each of core tubes 54 has rounded sides 160 extending in a widthwise direction. Methodology to produce arcuate shape 158 of first and second tabular portions 154 and 156 entails, for example, bending, rolling, or stretching sheet material 96 (FIG. 6) in the course of executing fin pack fabrication subprocess 92 (FIG. 5).
Arcuate shape 158 of tabular portions 154 and 156 enables tabular portions 154 and 156 to wrap around sides 160 of core tubes 54 so that closer contact is made between core tubes 54 and tabular portions 154 and 156. This closer contact can result in greater rigidity of the heat exchanger core, in enhanced heat transfer efficiency, and facilitate laminar flow of air around rounded sides 160 of core tubes 52 and tabular portions 154 and 156.
In summary, the present invention teaches of a fin pack that includes multiple rows of continuous corrugated fins interconnected by tabular portions. The multiple rows of fins are spaced apart by channels in which core tubes of a heat exchanger can be inserted. A production method yields the fabrication of a fin pack having multiple interconnected rows of fins using one coil of sheet material. The production method further enables the concurrent installation of multiple core tubes into the channels between the multiple rows of fins to form a heat exchanger core. The fin pack of the present invention results in improved appearance of a heat exchanger, a reduction in dropped and misaligned fins, and a reduction in defective parts and waste relative to prior art designs. In addition, the production methodology enables concurrent installation of multiple fin rows with core tubes of a heat exchanger resulting in an improved appearance of the heat exchanger and cost savings in terms of a more efficient manufacture process time.
Although the preferred embodiments of the invention have been illustrated and described in detail, it will be readily apparent to those skilled in the art that various modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.
Patent Application
20090145587
