Patent Publication Number: US-6216777-B1

Title: Manifold for a heat exchanger and method of making same

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to heat exchangers for motor vehicles and, more specifically, to a manifold and method of making same for a heat exchanger in a motor vehicle. 
     2. Description of the Related Art 
     It is known to provide a heat exchanger such as a condenser for an air conditioning system of a motor vehicle. The heat exchanger typically includes a plurality of U-shaped tubes having a fluid passing therethrough and a plurality of fins extending between the tubes. The number of U-shaped tubes depends on thermal capacity requirements of the heat exchanger. In order to connect these tubes together so that the fluid can flow through the tubes, manifolds are used having a series of openings corresponding to and mating with the ends of the tubes. The manifolds have an inlet port and an outlet port which circulate the fluid through the heat exchanger and then return the fluid to a remote location for subsequent recycling. 
     It is also known to fabricate manifolds as an extrusion using an extruding process. An example of such a method to make a manifold is disclosed in U.S. Pat. No. 5,190,101. In this patent, a manifold for a heat exchanger is fabricated by extruding a generally planar base member with a U-shaped channel disposed below a plane thereof and a pair of vertically depending walls projecting generally perpendicularly to the plane of the base member. The method includes forming a plurality of fluid conducting passageways in the base member and rolling the vertical depending walls toward a longitudinal center of the base member until the free ends of the walls are disposed in the channel of the base member to form fluid conduits. However, these extruded manifolds are relatively expensive to produce. 
     It is further known to fabricate manifolds as a stamping using a stamping process. An example of such a method to make a manifold is disclosed in U.S. Pat. No. 5,163,509. In this patent, a manifold assembly for a heat exchanger includes a first manifold and a second manifold. The first manifold has a first hollow conduit and a first plurality of apertures through the first conduit. The second manifold has a second hollow conduit and a second plurality of apertures through the second conduit. The manifold assembly includes at least one joining member between the first and second manifolds for joining the first manifold to the second manifold with the first conduit being side-by-side and adjacent the second conduit. The joining member includes a region of weakness for facilitating separation of the first and second manifolds. The manifold assembly is fabricated by stamping and bending a single elongate sheet metal strip. 
     Although the above manifolds have worked, they suffer from the disadvantage that the extruded manifolds are relatively costly to manufacture. Another disadvantage of the above manifolds is that the stamped manifolds have a portion extending above the plane of the fluid conduits. Yet another disadvantage of the above manifolds is that the stamped manifolds have a pair of seams that are brazed which may result in leakage of fluid if not brazed properly. Still another disadvantage of the above manifolds is that extruded manifolds have a U-shaped channel disposed below a plane of the base member, which is undesired. Therefore, there is a need in the art to provide a manifold for a heat exchanger of a motor vehicle that overcomes these disadvantages. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is a manifold for a heat exchanger including a base member having a plurality of tubular members for connection to tubes of a heat exchanger. The manifold also includes a plurality of folds disposed between the tubular members to form a channel above a plane of the base member. The manifold includes a first side member extending from a side edge of the base member and a second side member extending from another side of the base member and opposing the first side member. The free ends of the first side member and the second side member are disposed in the channel and secured in place between the folds to define a first fluid conduit and a second fluid conduit. 
     Also, the present invention is a method of making a manifold for a heat exchanger. The method includes the steps of providing a generally planar sheet having a base member with a plurality of tubular members for connection to tubes of a heat exchanger. The method also includes the step of folding the sheet and forming a plurality of folds between the tubular members to form a channel above a plane of the base member. The method includes the step of folding lateral side edges of the sheet to form a first side member and a second side member opposing each other. The method further includes the step of folding free ends of the first side member and the second side member toward each other and disposing the free ends in the channel to define a first fluid conduit and a second fluid conduit. 
     One advantage of the present invention is that a stamped manifold for a heat exchanger such as a condenser is provided for an air conditioning system of a motor vehicle for condensing liquid refrigerant. Another advantage of the present invention is that the manifold uses a sheet that is stamped, folded and brazed to make a manifold. Yet another advantage of the present invention is that the manifold is stamped and folded and is less costly and more economical to manufacture than an extruded manifold. 
     Other features and advantages of the present invention will be readily appreciated, as the same becomes better understood after reading the subsequent description taken in conjunction with the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a manifold, according to the present invention, illustrated in operational relationship with a heat exchanger. 
     FIG. 2 is a sectional view taken along line  2 — 2  of FIG.  1 . 
     FIGS. 3A through 3D illustrate steps of a method, according to the present invention, of making the manifold of FIG.  1 . 
     FIG. 4 is a partial fragmentary view of another embodiment, according to the present invention, of the manifold of FIGS. 1 and 2. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     Referring to the drawings and in particular FIG. 1, one embodiment of a heat exchanger  10 , such as a condenser for an air conditioning system (not shown), is shown for a motor vehicle (not shown). The heat exchanger  10  is of a tube and fin type and includes a plurality of U-shaped tubes  12  with a plurality of heat dissipative fins  14  extending between each of the tubes  12 . The heat exchanger  10  also includes a manifold, generally indicated at  16  and according to the present invention, matingly engaging generally cup-shaped free ends  17  of the tubes  12  and disposed at one end of the heat exchanger  10 . As illustrated, the manifold  16  is a double chambered manifold having a first fluid conduit  18  and a second fluid conduit  20 . The first fluid conduit  18  includes an inlet port  22  for receiving fluid therein and the second fluid conduit  20  includes an outlet port  24  for discharge of fluid therefrom. Fluid to be cooled (or heated) enters the manifold  16  through the inlet port  22  and is directed through the tubes  12  wherein the fluid is cooled by a secondary fluid, such as air, passing over the fins  14 . Baffles (not shown) in the manifold  16  direct the fluid through the tubes  12  wherein the fluid eventually discharges from outlet port  24 . The heat exchanger  10  may include end plates  26  to support the tubes  12  for the manifold  16 . It should be appreciated that, except for the manifold  16 , the heat exchanger  10  is conventional and known in the art. It should also be appreciated that the manifold  16  could be used for heat exchangers in other applications besides motor vehicles. 
     Referring to FIGS. 1 and 2, the manifold  16  extends longitudinally. The manifold  16  includes a base member  28  being generally planar and extending laterally. The manifold  16  also includes a plurality of tubular members  30  extending generally perpendicular to the base member  28 . The tubular members  30  have a generally circular cross-sectional shape with a fluid passageway  32  extending therethrough and fluidly communicating with the first fluid conduit  18  and the second fluid conduit  20 . The tubular members  30  and base member  28  are integral, unitary and formed as one-piece from a metal material such as aluminum. It should be appreciated that the tubular members  30  are secured to the tubes  12  by suitable means such as brazing. 
     The manifold  16  also includes a first side member  34  along one side of the base member  28 . The first side member  34  is generally arcuate in cross-sectional shape. The manifold  16  includes a second side member  36  along the other side of the base member  28  and opposing the first side member  34 . The second side member  36  is generally arcuate in cross-sectional shape. The first and second side members  34  and  36  and the base member  28  are integral, unitary and formed as one piece from a metal material such as aluminum. It should be appreciated that the first side member  34  and second side member  36  may have any suitable cross-sectional shape. 
     The manifold  16  includes at least one, preferably a plurality of folds  38  extending from the base member  28  between a pair of laterally spaced tubular members  30  to form a channel  40 . In the embodiment illustrated, two folds  38  are spaced laterally and extend generally perpendicular to and above a plane of the base member  28 . Each of the folds  38  extends longitudinally and has a first portion  42  and a second portion  44 . Each fold  38  is formed by folding the base member  28  to form the first portion  42  and back on itself to form the second portion  44  to obtain a predetermined fold height. In the embodiment illustrated, the predetermined fold height is approximately 5.5 mm. The folds  38  and base member  28  are integral, unitary and formed as one-piece from a metal material such as aluminum. It should be appreciated that the channel  40  is disposed above the plane of the base member  28 . 
     After the folds  38  are formed, the free ends of the first side member  34  and second side member  36  are disposed in the channel  40  to form the first fluid conduit  18  and second fluid conduit  20 , respectively. The manifold  16  has its inner and outer surfaces coated with a known brazing material. As a result, the brazing material flows between the base member  28 , folds  38 , first side member  34  and second side member  36  by capillary flow action to braze the first side member  34  and second side member  36  and base member  28  together in the channel  40 . 
     Referring to FIGS. 3A through 3D, a method, according to the present invention, of the making the manifold  16  is shown. The method includes the step of providing a generally planar sheet  50  of elongate, deformable material such as aluminum coated with a braze material. The method includes the step of forming the sheet  50  into a base member  28  with tubular members  30  and having the first side member  34  and second side member  36  along a longitudinal length thereof as illustrated in FIG.  3 A. The sheet  50  is provided as a stamping. The method includes the step of folding the sheet  50  between the tubular members  30  to form the folds  38  with the first portion  42  and the second portion  44  to a predetermined fold height above a plane of the base member  28  as illustrated in FIG.  3 B. The method includes the step of flanging the lateral outer edges of the sheet  50  to form the first side member  34  and second side member  36  as illustrated in FIG.  3 C. The method also includes the step of folding or rolling the first side member  34  and second side member  36  toward one another until their free ends are disposed in and meet in the channel  40  to form the first fluid conduit  18  and second fluid conduit  20  as illustrated in FIG.  3 D. The free ends of the first side member  34  and second side member  36  are locked or secured in place between the folds  38 . The method includes the step of forming ends of the fluid conduits  18  and  20  and assembling adapters into drilled holes in the first and second side members  32  and  34  to form the inlet  22  and outlet  24 . The method includes the step of brazing the manifold  16  by heating the manifold  16  to a predetermined temperature to melt the brazing material to braze the base member  28 , folds  38 , first side member  34  and second side member  36  together and cooling the manifold  16  to solidify the molten braze material to secure the base member  28 , folds  38 , first side member  34  and second side member  36  together. 
     Referring to FIG. 4, another embodiment  116 , according to the present invention, of the manifold  16  is shown. Like parts of the manifold  16  have like reference numerals increased by one hundred (100). In this embodiment, the free ends of the first side member  134  and second side member  136  have side margins or edges  152  and  154 , respectively, of a thickness less than a thickness of a remainder thereof. The side edges  152  and  154  are disposed in the channel  140 . The side edges  152  and  154  allow the channel  140  to have a width less than the width of the remainder or original thickness of both side members  134  and  136 . The side edges  152  and  154  may be formed by laterally compressing the folds  138  after the side members  134  and  136  are disposed therebetween. 
     Accordingly, the manifold  16  is a cost reduction over current manifolds that are made from a dual extruded tube with tubular members back extruded. The manifold  16  has a sheet with extruded tubular members or risers and is folded and brazed to make the manifold. 
     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 of the present invention 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.