Patent Publication Number: US-6209629-B1

Title: Beaded plate 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 beaded plate and method of making same for a heat exchanger in a motor vehicle. 
     2. Description of the Related Art 
     It is known to provide plates for a heat exchanger such as an oil cooler in a motor vehicle. Typically, opposed plates carry a first fluid medium in contact with an interior thereof while a second fluid medium contacts an exterior thereof. Typically, the first fluid medium is oil and the second fluid medium is air. Where a temperature difference exists between the first and second fluid mediums, heat will be transferred between the two via heat conductive walls of the plates. 
     It is also known to provide corrugated fins or ribs sandwiched between pairs of plates of a heat exchanger such as an oil cooler that act as a turbulator to increase the fluid side heat transfer coefficient while having to accept an appreciable amount of fluid side pressure drop. One known method of making such a construction is to physically insert a corrugated fin into the space between the plates after the plates have been manufactured. This is an extremely difficult process since the corrugated fin to be inserted between the plates is extremely thin and subject to deformation during the insertion process. 
     It is also known to provide beaded plates for a heat exchanger in which beads define a plurality of passageways between the plates for movement of a fluid therethrough to increase the surface area of conductive material available for heat transfer to cause turbulence of the fluid carried between the plates. An example of such a heat exchanger is disclosed in U.S. Pat. No. 4,600,053. In this patent, each of the plates has a plurality of beads formed thereon with one plate having one distinct variety of beads and the other plate having another distinct variety of beads. The beads of the plates contact each other and are bonded together to force fluid to flow therearound. The beads are aligned in rows in which one row has an “A” pattern and the adjacent or next row has a “B” pattern in which the beads are aligned with spaces of the A pattern. The rows are repeated in an AB pattern in which the beads in the A rows are aligned longitudinally or downstream with each other and the beads in the B rows are aligned longitudinally or downstream with each other. 
     Although the above heat exchangers have worked well, it is desirable to eliminate the use of a turbulator between the plates of a heat exchanger. It is also desirable to provide beaded plates for a heat exchanger having a repeating row pattern of non-aligned beads. It is still desirable to provide beaded plates for a heat exchanger that offer less resistance to flow than equal-sized turbulated heat exchangers with comparable heat rejection. 
     SUMMARY OF THE INVENTION 
     Accordingly, the present invention is a beaded plate for a heat exchanger including a plate having a generally planar surface and a plurality of beads extending generally perpendicular to the surface of the plate. The beads are formed in a repeating pattern of non-aligned beads within a plurality of rows of the beads. 
     Also, the present invention is a method of making a beaded plate for a heat exchanger. The method includes the steps of providing a plate having a generally planar surface and forming a plurality of beads generally perpendicular to the surface of the plate in a repeating pattern of non-aligned beads within a plurality of rows of the beads. 
     One advantage of the present invention is that a beaded plate for a heat exchanger such as an oil cooler is provided for a motor vehicle for cooling liquid oil. Another advantage of the present invention is that the beaded plate eliminates the need for a separate turbulator between plates for a heat exchanger such as an oil cooler. Yet another advantage of the present invention is that the beaded plate has a repeating pattern of non-aligned beads within a number of rows of the beads. Still another advantage of the present invention is that the beaded plate offers less resistance to flow than equal-sized turbulated oil coolers with comparable heat rejection. A further advantage of the present invention is that a method of making a beaded plate for an oil cooler is provided which uses less material, parts and complexity for assembly. Yet a further advantage of the present invention is that the beaded plate more evenly distributes the enhanced heat transfer and mixing along the depth of the plate than occurs with more traditional alignments of rows and columns of beads. 
     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 fragmentary elevational view of a beaded plate, according to the present invention, illustrated in operational relationship with a heat exchanger for a motor vehicle. 
     FIG. 2 is a sectional view taken along line  2 — 2  of FIG.  1 . 
     FIG. 3 is a sectional view taken along line  3 — 3  of FIG.  2 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     Referring to the drawings and in particular FIG. 1, one embodiment of a heat exchanger  10 , according to the present invention, such as an oil cooler, evaporator or condenser, is shown for a motor vehicle (not shown). The heat exchanger  10  includes a plurality of generally parallel beaded plates  12 , according to the present invention, pairs of which are joined together in a face-to-face relationship to provide a channel  14  therebetween. The heat exchanger  10  also includes a plurality of convoluted or serpentine fins  16  attached an exterior of each of the beaded plates  12 . The fins  16  are disposed between each pair of the joined beaded plates  12  to form a stack. The fins  16  serve as a means for conducting heat away from the beaded plates  12  while providing additional surface area for convective heat transfer by air flowing over the heat exchanger  10 . The heat exchanger  10  further includes oppositely disposed first and second mounting plates  18  and  20  at ends of the stack. The mounting plates  18 , 20  fluidly communicate with flow headers, generally indicated at  21 , formed by bosses  22  on each of the beaded plates  12 . The heat exchanger  10  includes a fluid inlet  24  for conducting fluid into the heat exchanger  10  formed in the first mounting plate  18  and an outlet  26  for directing fluid out of the heat exchanger  10  formed in the second mounting plate  18 . It should be appreciated that, except for the beaded plates  12 , the heat exchanger  10  is conventional and known in the art. It should also be appreciated that the beaded plates  12  could be used for heat exchangers in other applications besides motor vehicles. 
     Referring to FIGS. 1 through 3, the beaded plate  12  extends longitudinally and is substantially planar or flat. The beaded plate  12  includes a raised boss  22  on each end having an aperture  27  extending therethrough. The bosses  22  are stacked together such that the apertures  27  are aligned to form the flow header  21  to allow parallel flow of fluid through the channels  14  of the beaded plates  12 . It should be appreciated that such flow headers  21  are conventional and known in the art. 
     The beaded plate  12  includes a surface  28  being generally planar and extending longitudinally and laterally. The beaded plate  12  also includes a plurality of beads  30  extending above and generally perpendicular to a plane of the surface  28  and spaced laterally from each other. The beads  30  are generally circular in shape and have a predetermined diameter such as three millimeters. The beads  30  have a side wall  32  extending at an angle to the surface  28  from a larger diameter to a smaller diameter that terminates in a generally planar end wall  34 . The end wall  34  forms a predetermined diameter such as 1.5 millimeters and has an aperture  36  extending therethrough. It should be appreciated that the beads  30  have a generally frusto-conical cross-sectional shape. 
     As illustrated in FIG. 2, the beads  30  are formed in a pattern  38  of a plurality of rows, at least three rows in the pattern  38 , preferably four rows A,B,C,D, in the pattern  38 , which is repeated. Each row A,B,C,D contains a plurality of, preferably a predetermined number of beads  30  in a range of two to eleven. The rows A,B,C,D of beads  30  are spaced longitudinally a predetermined distance such as approximately 2.45 millimeters. The beads  30  in the rows A,B,C,D are located laterally so that no bead  30  is directly downstream of another bead  30  within the pattern  38 . The beads  30  in the pattern  38  are non-aligned in the streamwise or longitudinal direction as indicated by the arrows  40 . The pattern  38  is repeated in the streamwise or longitudinal direction as indicated by the arrows  40 . It should be appreciated that a row A,B,C,D could contain all full beads  30  or full and half beads  30 . 
     The beaded plate  12  is made of a metal material such as aluminum or an alloy thereof and has a cladding on its inner and outer surfaces for brazing. In the embodiment illustrated, a pair of the beaded plates  12  is arranged such that the end walls  34  of the beads  30  contact each other to form a plurality of flow passages  42  in the channel  14  as illustrated in FIGS. 1 and 3. The beads  30  turbulate fluid flow through the channel  32 . It should be appreciated that the end walls  34  of the beads  30  are brazed to each other. It should also be appreciated that the entire heat exchanger  10  is brazed together as is known in the art. 
     Referring to FIGS. 1 through 3, a method of making the beaded plate  12 , according to the present invention, is shown. The method includes the step of providing a plate  12  having a generally planar surface  28 . The method includes the step of forming a plurality of beads  30  to extend above the surface  28  of the plate  12  in a repeating pattern  38  of non-aligned beads  30  within a plurality of rows A,B,C,D in the pattern  38  as illustrated in FIG.  2 . The step of forming is carried out by stamping the beads  30  in the plate  12  by conventional stamping processes. 
     Also, a method of making the heat exchanger  10 , according to the present invention, is shown. The method includes the step of contacting first and second beaded plates  12  with each other to form the channel  14  therebetween and contact opposed beads  30  with each other to form the fluid flow passages  42  as illustrated in FIGS. 1 and 3. The method includes the step of brazing a pair of the beaded plates  12  by heating the beaded plates  12  to a predetermined temperature to melt the brazing material to braze the bosses  22  and the beads  30  of the beaded plates  12  together. The pair of joined beaded plates  12  is then cooled to solidify the molten braze material to secure the bosses  22  together and the beads  30  together. The method includes the step of disposing fins  16  between joined pairs of the beaded plates  12  and brazing the fins  16  and beaded plates  12  together. The method includes the steps of connecting the first and second mounting plates  18  and  20  to the brazed fins  16  and beaded plates  12  to form the heat exchanger  10 . 
     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.