Abstract:
A heat exchanger with multi-flow capabilities includes a pair of intermediate tanks located between a pair of header tanks. An open gap is provided between the two intermediate tanks. A first plurality of tubes extend between the header tanks. A second plurality of tubes extend between one of the header tanks and one of the intermediate tanks. A third plurality of tubes extend between the other header tank and the other intermediate tank. In a two flow system, the two intermediate tanks are in fluid communication through a flexible jumper tube. In a three flow system the two intermediate tanks are isolated from each other. The open gap between the intermediate tanks allows for the uneven heat expansion between the various fluid flows.

Description:
FIELD 
     The present disclosure relates to a heat exchanger. More particularly, the present disclosure relates to a multi-cooling heat exchanger for cooling two or more fluids while reducing the strain on the heat exchanger which occurs due to the different temperatures of the two or more fluids. 
     BACKGROUND 
     This section provides background information related to the present disclosure which is not necessarily prior art. 
     The conventional multi-cooling heat exchanger includes a core portion having a plurality of tubes, a header tank attached to both ends of the tubes, a plurality of fins disposed between adjacent tubes and an insert or side plate that provides stability to the heat exchanger. The header tanks are separated along their length to provide two or more separate cooling sections for the heat exchanger. A first fluid flows through the first section of the header tanks and tubes and a second fluid flows through the second section of the header tanks and tubes. Typical examples of the first fluid is refrigerant from an air conditioning system and a typical example for the second fluid is transmission oil. Both fluids are cooled as they pass through the plurality of tubes. 
     These multi-cooler heat exchangers develop a high amount of thermal strain. This is due to one of the fluids having a higher operating temperature than the other fluid. This temperature difference leads to a higher thermal expansion in the cooling section which cools the higher temperature fluid. Since both sections of the tubes are constrained by the header tanks, thermal strain occurs. 
     To alleviate this thermal strain, it is known to saw cut one or both of the header tanks to allow the higher temperature fluid section to expand freely and reduce the thermal strain. This method is effective but it adds labor and production time to the process. Another method for reducing this thermal strain is to make a saw cut in the insert or side plate. During cold weather operation, the plurality of tube expand due to increased temperature and the insert or side plate tends to heat up at a slower rate which causes a second source of thermal strain. The saw cut in the insert or side plate reduces this thermal strain but it still requires additional labor and production time. 
     SUMMARY 
     This section provides a general summary of the disclosure, and is not a comprehensive disclosure of its full scope or all of its features. 
     The present disclosure allows for the cooling of two or more fluids which flow in parallel through different sections of the plurality of tubes. The thermal strain is reduced in the present disclosure by providing intermediate tanks between the two header tanks. The two tanks are spaced from each other to define an open gap between them which allows for the difference in thermal expansion of the different sections of the heat exchanger. 
     Further areas of applicability will become apparent from the description provided herein. The description and specific examples in this summary are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure. 
    
    
     
       DRAWINGS 
       The drawings described herein are for illustrative purposes only of selected embodiments and not all possible implementations, and are not intended to limit the scope of the present disclosure. 
         FIG. 1  is a front view of a heat exchanger in accordance with the present disclosure; 
         FIG. 2  is a top view of the heat exchanger illustrated in  FIG. 1 ; 
         FIG. 3  is a front view of a heat exchanger in accordance with another embodiment of the present invention; 
         FIG. 4  is a front view of a heat exchanger in accordance with another embodiment of the present invention; 
         FIG. 5  is a front view of a heat exchanger in accordance with another embodiment of the present invention; 
         FIG. 6  is a front view of a heat exchanger in accordance with another embodiment of the present invention; 
         FIG. 7  is a front view of a heat exchanger in accordance with another embodiment of the present invention; 
         FIG. 8  is a front view of a heat exchanger in accordance with another embodiment of the present invention; 
         FIG. 9  is a front view of a heat exchanger in accordance with another embodiment of the present invention; and 
         FIGS. 10A-10C  illustrate the fluid passages in the tubes of the heat exchanger. 
     
    
    
     Corresponding reference numerals indicate corresponding parts throughout the several views of the drawings. 
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully with reference to the accompanying drawings. Referring now to  FIGS. 1 and 2 , a heat exchanger  10  in accordance with the present disclosure is illustrated. Heat exchanger  10  comprises a first plurality of tubes  12 , a second plurality of tubes  14 , a third plurality of tubes  16 , a first plurality of fins  18 , a second plurality of fins  20 , a third plurality of fins  22 , a first side plate  24 , a second side plate  26 , a third side plate  28 , a first header tank  30 , a second header tank  32 , a first intermediate tank  34 , a second intermediate tank  36  and one or more flexible jumper tubes  38 . 
     Each of the first, second and third plurality of tubes  12 ,  14 ,  16  are arranged in parallel to each other and each tube is flat so that the direction of the air flow (perpendicular to the page in  FIG. 1 ) coincides with the longer portion of the flat tube. The flat surfaces of the first, second and third plurality of tubes  12 ,  14 ,  16  are coupled with the first, second and third plurality of fins  18 ,  20 ,  22  as illustrated in  FIG. 1 . Each of the first, second and third plurality of tubes define one or more internal passages through which fluid flows. The shape of each internal passage can be rectangular, round, oval, star shaped or any other shape. Also, the shape of the passages in the first, second and third plurality of tubes can be different from each other. As illustrated in  FIGS. 10A-10C , tubes  12  have a circular shape, tubes  14  have a rectangular shape and tubes  16  have a star shape. The plurality of fins  18 ,  20 ,  22  increase the transfer area with the air to promote the heat exchange between the fluid within the plurality of tubes  12 ,  14 ,  16  and the air. The substantially rectangular heat exchanging unit including the plurality of tubes  12 ,  14 ,  16  and the plurality of fins  18 ,  20  and  22  is hereinafter referred to as core portion  40 . 
     First and second header tanks  30  and  32  extend in the stacking direction of the plurality of tubes  12 ,  14 ,  16  and the plurality of fins  18 ,  20 ,  22  perpendicular to the length of the plurality of tubes  12 ,  14 ,  16 . First header tank  30  includes a first inlet  42 , a first outlet  44  and a second outlet  46 . A first internal baffle (not shown) separates first inlet  42  from first outlet  44  and a second baffle (not shown) separates first inlet  42  from second outlet  46 . Second header tank  32  includes a second inlet  48 . A third internal baffle separates second inlet  48  from the lower portion of second header tank  32 . First and second intermediate tanks  34  and  36  are disposed adjacent each other as shown in  FIGS. 1 and 2 . An open gap  56  extends entirely between first intermediate tank  34  and second intermediate tank  36  to allow for the expansion of the second and the third plurality of tubes  14 ,  16  with respect to the first plurality of tubes  12  as discussed below. The one or more flexible jumper tubes  38  extend between first intermediate tank  34  and second intermediate tank  36  to channel fluid flow between intermediate tanks  34  and  36 . 
     First side plate  24  extends along the lower end of the first plurality of fins  18 . Second side plate  26  extends along the upper end of the second plurality of fins  20 . Third side plate  28  extends along the upper end of the third plurality of fins  22 . First, second and third side plates  24 ,  26  and  28  provide support for core portion  40 . 
     The first plurality of tubes  12  are in fluid communication with first and second header tanks  30  and  32 . The second plurality of tubes  14  are in fluid communication with first header tank  30  and first intermediate tank  34 . The third plurality of tubes  16  are in fluid communication with the second intermediate tank  36  and the second header tank  32 . As discussed above, first intermediate tank  34  is in fluid communication with second intermediate tank  36  through the one or more flexible jumper tubes  38  illustrated in  FIGS. 1 and 2  as a tubular coil. 
     Thus, heat exchanger  10  defines two heat exchanging sections which have different fluids flowing through the sections. In the lower section, a first fluid is introduced into first inlet  42  into first header tank  30 . The first fluid flows from first header tank  30  through a portion of the first plurality of tubes  12  to second header tank  32  where the first fluid makes a turn and returns to first header tank  30  through the other portion of the first plurality of tubes  12  and leaves first header tank  30  through first outlet  44 . In the upper section, a second fluid, different from the first fluid, is introduced into second inlet  48  into second header tank  32 . The second fluid flows from second header tank  32  through the second plurality of tubes  14  and into first intermediate tank  34 , through the one or more flexible jumper tubes  38  into second intermediate tank  36 . The second fluid flows from second intermediate tank  36  through the third plurality of tubes  16  and into first header tank  30  and leaves first header tank  30  through second outlet  46 . 
     If the temperature of the second fluid is higher than the temperature of the first fluid the differences in the thermal expansion of the plurality of tubes  12 ,  14 ,  16  is compensated for by open gap  56  which reduces and/or eliminates the thermal strain which could occur due to the differences in thermal expansion of the plurality of tubes  12 ,  14 ,  16 . The one or more flexible jumper tubes  38  permit the movement between first intermediate tank  34  and second intermediate tank  36 . 
     Referring now to  FIG. 3 , a heat exchanger  60  in accordance with another embodiment of the present disclosure is illustrated. Heat exchanger  60  is the same as heat exchanger  10  except that the one or more flexible jumper tubes  38  have been replaced by one or more rubber jumper hoses  68  which are in fluid communication with first and second intermediate tanks  34  and  36 . The above description of heat exchanger  10  applies to heat exchanger  60  also. 
     Referring now to  FIG. 4 , a heat exchanger  70  in accordance with another embodiment of the present disclosure is illustrated. Heat exchanger  70  is the same as heat exchanger  10  except that the one or more flexible jumper tubes  38  have been replaced by jumper tube assembly  78  which is in fluid communication with first and second intermediate tanks  34  and  36 . Jumper tube assembly  78  includes a plurality of tubes  80  each of which are connected to another tube  80  or to first and second intermediate tanks  34  and  36  through a plurality of rotating quick connectors  82 . The above description of heat exchanger  10  applies to heat exchanger  70 . 
     Referring now to  FIG. 5 , a heat exchanger  90  in accordance with another embodiment of the present disclosure is illustrated. Heat exchanger  90  is the same as heat exchanger  10  except that the one or more flexible jumper tubes  38  have been replaced by one or more generally U-shaped jumper tubes  98  which are in fluid communication with first and second intermediate tanks  34  and  36 . The above description of heat exchanger  10  applies to heat exchanger  90 . 
     Referring now to  FIG. 6 , a heat exchanger  110  in accordance with the present disclosure is illustrated. Heat exchanger  110  comprises the first plurality of tubes  12 , the second plurality of tubes  14 , the third plurality of tubes  16 , the first plurality of fins  18 , the second plurality of fins  20 , the third plurality of fins  22 , the first side plate  24 , the second side plate  26 , the third side plate  28 , a first header tank  130 , a second header tank  132 , the first intermediate tank  34  and the second intermediate tank  36 . 
     Each of the first, second and third plurality of tubes  12 ,  14 ,  16  are arranged in parallel to each other and each tube is flat so that the direction of the air flow (perpendicular to the page in  FIG. 1 ) coincides with the longer portion of the flat tube. The flat surface of the first, second and third plurality of tubes  12 ,  14 ,  16  are coupled with the first, second and third plurality of fins  18 ,  20 ,  22  as illustrated in  FIG. 6 . The plurality of fins  18 ,  20 ,  22  increase the transfer area with the air to promote the heat exchange between the fluid within the plurality of tubes  12 ,  14 ,  16  and the air. The substantially rectangular heat exchanging unit including the plurality of tubes  12 ,  14 ,  16  and the plurality of fins  18 ,  20  and  22  is hereinafter referred to as core portion  40 . 
     First and second header tanks  130  and  132  extend in the stacking direction of the plurality of tubes  12 ,  14 ,  16  and the plurality of fins  18 ,  20 ,  22  perpendicular to the length of the plurality of tubes  12 ,  14 ,  16 . First header tank  130  includes first inlet  42 ; first outlet  44 , second outlet  46 , and second inlet  48 . A first internal baffle (not shown) separates first inlet  42  from first outlet  44 , a second baffle (not shown) separates first inlet  42  from second outlet  46  and a third internal baffle separates second outlet  46  from second inlet  48 . Second header tank  132  includes a third inlet  50  and a third outlet  52 . An internal baffle (not shown) separates third inlet  50  from third outlet  52 . First and second intermediate tanks  34  and  36  are disposed adjacent each other as shown in  FIGS. 1 and 2 . Open gap  56  extends entirely between first intermediate tank  34  and second intermediate tank  36  to allow for the expansion of the second and third plurality of tubes  14 ,  16  with respect to the first plurality of tubes  12  as discussed below. There is no fluid flow between first intermediate tank  34  and second intermediate tank  36 . 
     First side plate  24  extends along the lower end of the first plurality of fins  18 . Second side plate  26  extends along the upper end of the second plurality of fins  20 . Third side plate  28  extends along the upper end of the third plurality of fins  22 . First, second and third side plates  24 ,  26  and  28  provide support for core portion  40 . 
     The first plurality of tubes  12  are in fluid communication with first and second header tanks  130  and  132 . The second plurality of tubes  14  are in fluid communication with first header tank  130  and first intermediate tank  34 . The third plurality of tubes  16  are in fluid communication with the second intermediate tank  36  and the second header tank  132 . As discussed above, first intermediate tank  34  is not in fluid communication with second intermediate tank  36 . 
     Thus, heat exchanger  10  defines three heat exchanging sections which have different fluids flowing through the sections. In the lower section, a first fluid is introduced into first inlet  42  into first header tank  130 . The first fluid flows from first header tank  130  through a portion of the first plurality of tubes  12  to second header tank  132  where the first fluid makes a U-turn and returns to first header tank  130  through the other portion of the first plurality of tubes  12  and leaves first header tank  130  through first outlet  44 . In one of the upper sections, a second fluid, different from the first fluid, is introduced into second inlet  48  into first header tank  130 . The second fluid flows from first header tank  130  through a portion of the second plurality of tubes  14  and into first intermediate tank  34  where the second fluid makes a U-turn and returns to first header tank  130  through the other portion of the second plurality of tubes  14  and leaves first header tank  130  through second outlet  46 . In the other of the upper sections, a third fluid, different than the first and second fluids, is introduced into third inlet  50  into second header tank  132 . The third fluid flows from second header tank  132  through a portion of the third plurality of tubes  16  and into second intermediate tank  36  where the third fluid makes a U-turn and returns to the second header tank  132  through the other portion of the third plurality of tubes  16  and leaves second header tank  132  through third outlet  52 . 
     If the temperature of the second fluid and/or the third fluid is higher than the temperature of the first fluid the differences in the thermal expansion of the plurality of tubes  12 ,  14 ,  16  is compensated for by open gap  56  which reduces and/or eliminates the thermal strain which could occur due to the differences in thermal expansion of the plurality of tubes  12 ,  14 ,  16 . 
     Referring now to  FIG. 7 , a heat exchanger  140  in accordance with the present disclosure is illustrated. Heat exchanger  140  is the same as heat exchanger  110  except that the pitch of the second plurality of fins  20  is different than the pitch of the first and third plurality of fins  18  and  22 . While only the pitch of the second plurality of fins  18  is illustrated as being different, each of the first, second and third plurality of fins  18 ,  20  and  22  could have different pitches. The above description of heat exchanger  110  applies to heat exchanger  140  also. 
     Referring now to  FIG. 8 , a heat exchanger  150  in accordance with the present disclosure is illustrated. Heat exchanger  150  is the same as heat exchanger  110  except that the length of the second plurality of tubes  14  and the second plurality of fins  20  is different than the length of the third plurality of tubes  16  and the third plurality of fins  22 . In addition, the thickness of the second plurality of tubes  14  is different than the thickness of the third plurality of tubes  16 . The above description of heat exchanger  110  applies to heat exchanger  150  also. 
     Referring now to  FIG. 9 , a heat exchanger  160  in accordance with the present disclosure is illustrated. Heat exchanger  160  is the same as heat exchanger  110  except that the pitch of the second plurality of tubes  14  is different than the pitch of the third plurality of tubes  16 . In addition, the thickness of the second plurality of tubes  14  is different than the thickness of the third plurality of tubes  16 . The above description of heat exchanger  110  applies to heat exchanger  160  also. 
     The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.