Abstract:
A gas/liquid heat exchanger includes a stack of abutting, substantially identical plates that are arranged in alternating fashion to define first and second flow channels. End plates are placed on the stack of the aforementioned plates. The core allows straight through flow of gas in the first fluid passageways which may be made relatively large and the use of a cooling liquid flow through the second coolant passageways for cooling the gas in the first coolant passageways.

Description:
FIELD OF THE INVENTION 
     This invention relates to heat exchangers, and more particularly, to heat exchangers adapted to exchange heat between a gas and a liquid as, for example, a water cooled charge air cooler or an exhaust gas heat exchanger as are used in vehicles to cool combustion air from a turbo charger or engine exhaust gas. 
     BACKGROUND OF THE INVENTION 
     Charge air coolers and exhaust gas heat exchangers are known to increase efficiency of operation of vehicles and/or reduce pollution. One such typical heat exchanger, specifically described as an exhaust gas heat exchanger, is disclosed in EP 677 715 A1 and employs shell like, heat exchanger plates that are employed in a heat exchanger where exhaust gas is cooled with cooling air. The flow channels for the exhaust formed by the shell-like heat exchanger plates are arranged in a pre-arranged spacing with cooling air passed through the spaces between adjacent plates. However, where cooling of the exhaust gas is achieved by a cooling liquid as, for example, engine coolant, then the flow channels for both the coolant and the exhaust gas are formed by means of plates that have rods or spacers between them to form the flow channels and are also enclosed by a housing, which forms the outer wall of the water cooling channels. This design, while effective, is costly to manufacture because a large number of individual parts of different configurations are required. 
     The present invention is directed to provide such a heat exchanger wherein the number of non-identical parts is minimized and the outer housing dispensed with. 
     SUMMARY OF THE INVENTION 
     It is the principal object of the invention to provide a new and improved gas/liquid heat exchanger. More specifically, it is an object of the invention to provide such a heat exchanger that is ideally suited for use as a charge air cooler or an exhaust gas heat exchanger. It is a further object of the invention to provide such a heat exchanger where the number of non-identical parts is minimized and the heat exchanger housing dispensed with. 
     A preferred embodiment of the invention contemplates a gas/liquid heat exchanger that includes a stack of abutting, substantially identical plates with there being first, second, third, fourth, . . . nth plates where “n” is an even integer of four or more. Each plate is a generally channel-shaped plate having a base with spaced sides and spaced ends extending between the spaced sides. Upstanding legs are located on the base with each leg extending along a corresponding side and being of equal height. Each leg terminates in a flange that is generally parallel to the base and each base includes a central section of raised height less than the height of the legs. The central section is spaced inwardly of the ends and the sides so as to be surrounded by a band of the base. The plates are stacked in the order 1, 2, 3, 4, . . . n in alternating fashion with the flanges on the first and second plates in abutment, the flanges on the third and fourth plates in abutment . . . and the flanges on the n-1 and the nth plates in abutment, and with the bands on the second and third plates in abutment . . . and the bands on the n-2 and n-1 plates in abutment. As a consequence, first flow channels exist between the first and second plates, the third and fourth plates, . . . and the n-1 and nth plates. Second flow channels exist between the central platforms of the second and third plates . . . and the n-2 and n-1 plates. Two side plates are provided, one on each of two opposite sides of the stack. First and second ports are located in the heat exchanger at opposite ends of the plates to be in fluid communication with the first flow channel and third and fourth parts are located in one or the other or both of the side plates and are in fluid communication with the second flow channels. 
     In one embodiment, there are a plurality of the central sections in each of the bases of the plates and each is surrounded by a band of the base. 
     A highly preferred embodiment contemplates the provision of dimples in the bases with the dimples in one base abutting the dimples in the base of one adjacent plate. 
     One embodiment of the invention contemplates that the substantially identical plates have spaced openings aligned with one another and with respective ones of the third and fourth ports. The substantially identical plates further include cup-shaped recesses in the platforms and opening oppositely of the central platform and surrounding the openings and sealed to one another. 
     The plates are sealed and bonded together at the flanges and at the bands. 
     One embodiment of the invention contemplates that there be fins in at least some of the flow channels and abutted to adjacent plates. 
     In one embodiment of the invention, the height of the legs is more than twice the height of the platform whereby the first flow channels are greater in size than the second flow channels. Preferably, fins are located in the first flow channels and are bonded to adjacent plates. 
    
    
     Other objects and advantages will become apparent from the following specification taken in connection with the accompanying drawings. 
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevation of a heat exchanger made according to the invention with parts broken away for clarity; 
     FIG. 2 is a fragmentary sectional view taken approximately along the line  2 — 2 - in FIG. 1; 
     FIG. 3 is a fragmentary, sectional view taken approximately along the line  3 — 3  in FIG. 1; 
     FIG. 4 is a fragmentary, sectional view taken approximately along the line  4 — 4  in FIG. 1; 
     FIG. 5 is a side elevation of the heat exchanger illustrated in FIG. 1 taken at 90° to the view of FIG. 1; 
     FIG. 6 is a sectional view taken approximately along the line  6 — 6  in FIG. 1; 
     FIG. 7 is a plan view of the heat exchanger shown in FIG. 1; 
     FIG. 8 is a view similar to FIG. 1 but of a modified embodiment of the heat exchanger; 
     FIG. 9 is a sectional view taken approximately along the line  9 — 9  in FIG. 8; 
     FIG. 10 is a side elevation of still another modified embodiment of the heat exchanger; 
     FIG. 11 is a sectional view taken approximately along the line  11 — 11  in FIG. 10; and 
     FIG. 12 is a fragmentary, sectional view taken approximately along the line  12 — 12  in FIG.  10 . 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A gas/liquid heat exchanger made according to the invention, and particularly suited for use as an exhaust gas heat exchanger is illustrated in the drawings. With reference to FIG. 1, it is seen to include an elongated heat exchanger core, generally designated  10 , and as seen in FIG. 5, is made up of a stack of identical plates  12 . While FIG. 5 shows there to be eight such plates  12 , it is to be understood that any plurality of plates  12  may be utilized. For example, the heat exchanger may be made up with as few as two plates although generally, it will have four or more. The number of the plates  12  will typically be an even integer equal to “n”, i.e., two, four, six, eight, etc. 
     As seen in FIG. 4, each of the plates  12  is generally in the form of an elongated channel having a base  14  flanked by side legs  16 . Each of the side legs  16  terminates in an outwardly directed flange  18  which is generally parallel to the base  14 . 
     The base  14  of each of the channel-shaped plates  12  is provided with a platform  20  located between the legs  16  on the sides of each channel and intermediate the ends  22  of the associated plates. The platform  20 , in the embodiment illustrated in FIG. 1, are spaced from the legs  16  by a band  24  of the base  14  and the arrangement is further such that in the usual embodiment, the height of each platform  20  relative to the surrounding band  24  is substantially less than half the height of the legs  16 . In all cases, the height of the platform  20  will be less than the height of the legs  16 . 
     As best seen in FIG. 3, the plates  12  are stacked in alternating fashion such that bands  24  of adjacent plates  12  are in contact with each other as are the flanges  18 . By alternating fashion, it is meant that the bases  14  of two adjacent plates  12  face each other to define first flow passages  28  while the platforms  20  also face each other to form second flow passages  30 . As somewhat schematically shown in FIG. 4, the flow passages  28  may be provided with undulating inserts  32  which contact and are bonded to, as by brazing, the bases  14  of adjacent plates. 
     More specifically, the flanges  18  of the first and second plates are in abutment as are the flanges on the third and fourth plates all the way up through the flanges on the n-1 and nth plates. At the same time, the bands  24  on the second and third plates are in abutment, and, if more than four plates are employed, the bands on the fourth and the fifth plates are in abutment up to the point where the bands on the n-2 and n-1 plates are also in abutment. Typically, the flanges  18  are sealed together as are the bands  14  as, for example, by a brazing assembly process. Consequently, each pair of the plates will define one of the first flow passages  28  and one of the second flow passages  30 . 
     As illustrated in the drawings, the flow passages  30  are considerably narrower than the flow passages  28  and are suited for receipt of a cooling liquid. The larger cross-section of the flow passages  28  make them suitable for receipt of a gas such as charge air or exhaust gas. Adjacent opposite ends  24  of the plates  12 , each of the platforms  20  include an edge  34  with the two edges  34  extending in opposite directions. That is, for the vertical orientation of the core  10  shown in FIG. 1, the lower bend  34  extends to the left while the upper bend  34  extends to the right to maintain identity of the plates  12 . The bends  34  extend to respective inlet and outlet ports  36 ,  38  which, as seen in FIGS. 5 and 6, include hose receiving nipples  40  and  42  respectively. At this location, each of the plates  12  includes an aperture  44  in the platform with the apertures  44  and each of the plates  12  being aligned with one another and being aligned with the port  36 . In addition, each of the apertures  44  is located in a cup-shaped stamping  46  that extends from the surface of the platform  20  a distance sufficient to be in the same plane as the corresponding flanges  18 . Thus, the bottoms of the cup-shaped recesses will be in contact with one another and may be sealed to one another during the assembly process, as by brazing. At the same time, a conduit for the ingress and exit of the coolant to and from the second flow paths  30  is provided by this structure. Flow is generally indicated by arrows  50  in FIG.  6 . 
     In many cases it is desirable that strengthening for the flow passages  30  be provided. This can be accomplished by using a symmetrical pattern of dimples  52  in each of the plates, which dimples are located in the platforms  20  on the bases  14  and extend oppositely of the cup-shaped formations  46 . As seen in FIG. 6, the dimples  52  align with and abut one another and may be bonded to one another during the assembly process, as by brazing. 
     As can be seen in FIG. 2, the plates  12  define the flow passages  28 , both above and below the opposite bends  34  with platforms  20 . A suitable fixture  60  is then secured to the ends  22  of the plates  12  to be connected, as by a hose clamp to conduit  62 . The conduit  62  conveys the gas with which heat is to be exchanged to and from the first flow passages  28 . It will be observed from FIG. 2 that at locations above the bends  34  in the case of the upper part of the core  10  as viewed in FIG. 1, dead spaces  64  exist at the locations that formerly defined the second flow passages  30  but for the presence of the bends  34 . 
     With reference to FIGS. 5,  6  and  7 , on each side of the stack of the plates  12  there is located an end plate  68 . The end plates  68  serve as boundaries to coolant flow in the second flow passages  30  on opposite sides of the stack of the plates  12 . The end plates  68  are preferably identical with one another but will not be identical to the plates  12 . 
     A modified embodiment is illustrated in FIGS. 8 and 9. Where like components are employed, like reference numerals will be utilized. A core  10  is formed of a stack of identical plates  100  of generally rectangular configuration. The plates  100  are again channel-shaped as best seen in FIG.  9  and include a base  102  provided with legs  104  extending down opposite sides thereof. The legs  104  again terminate in flanges  106  which abut one another in the same sequence mentioned previously. In the case of the embodiment illustrated in FIGS. 8 and 9, each base  102  is provided with a plurality of platforms  108 , in the illustrated embodiment, six in number. The platforms  108 , in turn, are surrounded by a band  110  of the base and the bands  108  of certain of the plates  100  are in abutment in the same sequence mentioned previously. 
     Disposed between adjacent ones of the platforms  106  is a symmetrical pattern of dimples  112  which, as seen in FIG. 9, extend oppositely from the associated plate of the platforms  106  thereon to be in abutment with dimples  112  on adjacent plates. Diagonally opposite inlet and outlet ports  36 ,  38  are included and fluid flow is in the direction of arrows  114 . 
     Each of the plates  100  includes an opening  116  with the openings  116  and the plates being aligned with one another and with appropriate one of the inlet  36  or outlet  38 . The openings are surrounded by cup-shaped elements  36  corresponding to those previously described whose bottoms abut one another and are sealed to one another. 
     Hose connectors  40 ,  42  (only the former is shown) are also provided as are end plates  68 . 
     The plate ends  120 , at locations exterior of the band  110  of the base  102  receive fixtures  122  for connection to the gas circuit whose gas is to exchange heat coolant flowed into the inlet  36  and out of the outlet  38 . 
     In this embodiment, it will be appreciated that the platforms  108  may be stepped as shown at  124 ,  126  to induce turbulence and thereby avoid the need of the undulating inserts  32 . As with the first embodiment, coolant flow paths are defined by the space between adjacent platforms and shown at  130  in FIG.  9 . These constitute the second coolant flow paths. And again, as in the case of the first embodiment, the first coolant flow path is defined by spaces  132  between the bases  102  of adjacent ones of the plates  100 . 
     A third embodiment is illustrated in FIGS. 10-12, inclusive, and combines features of both the embodiments heretofore described. Again, identical reference numerals will be utilized for identical components. 
     It will immediately be recognized that the embodiment of FIGS. 10-12 is quite similar to the embodiment illustrated in FIGS. 8 and 9. In this case, however, in order to avoid any restriction on the flow of gas posed by the presence of the cup-shaped elements  46 , the plates  100  have extensions  140  to each side of the basic rectangular configuration of the plates  100 . That is, the ports  36 ,  38  to the second coolant flow passages  130  are located out of rectangular envelope in the extensions  140 . 
     From the foregoing, it will be appreciated that three embodiments of the invention have been described which provide substantial advantages over the prior art. For example, no housing for the heat exchanger core is required, the housing being formed out of the core or heat exchanger plates themselves together with end plates. Moreover, all of the heat exchanger plates may be identical to one another minimizing the number of separate parts required. Similarly, the end plates may be of identical construction to again minimize the number of different parts required. In fact, only four different parts are required, namely, heat exchanger plates, end plates, hose nipples and inserts if used. At the same time, capacity of a given heat exchanger may be greatly increased or considerably reduced simply by selecting the appropriate number of heat exchanger plates to be employed. 
     The plates may be formed of aluminum and brazed together to achieve the seals between the flanges and the seals between the bands of the bases of each of the channel-shaped plates as well as the cup-shaped recesses. The plates are readily formed of aluminum sheet by conventional stamping or other forming processes.