Abstract:
A plate heat exchanger including first and second sets of heat exchanger plates. The second set plates are alternately stacked with the first set plates to form flow channels therebetween. The first set plates have first projections protruding in one direction from the plane of the plates and second projections protruding in the opposite direction from the plane of the plate. The second set plates have third projections protruding in the one direction from the plane of the second set plates. The first projections are connected to adjacent second set plates and the second projections protrude into the space between at least two of the third projections. The second projections may be spaced from and not connected to the second set plates, with the height of the third projections from the second set plates being greater than the height of the first and second projections from opposite sides of the first set plates.

Description:
CROSS REFERENCE TO RELATED APPLICATION(S)  
       [0001]     Not applicable.  
       STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
       [0002]     Not applicable.  
       REFERENCE TO A MICROFICHE APPENDIX  
       [0003]     Not applicable.  
       TECHNICAL FIELD  
       [0004]     The present invention relates to a plate heat exchanger, and more particularly a plate heat exchanger having at least two types of heat exchanger plates stacked to form flow channels between them with projections protruding from the plane of the plate connected to the adjacent heat exchanger plate.  
       BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE PRIOR ART  
       [0005]     Plate heat exchangers having projections from the plates are known, for example, from FIG. 8 of EP 742 418 B1 (prescribed there as oil coolers). They are also known from numerous other publications for other types of applications, including DE 100 34 343C2, DE 201 19 565 U1 and U.S. Pat. No. 4,781,248.  
         [0006]     Internal inserts, as opposed to projections formed in the plates themselves, are also often used with plate heat exchangers. However, such inserts often can cause difficult to remove residues to remain in the flow channels, including, for example, fine metallic chips that form during production of the internal inserts. If such residues reach the oil loop, for example, they can lead to failure of the system. Despite this, however, better heat exchange efficiency can often be achieved with internal inserts over heat exchangers in which the plate bottoms are shaped. In addition, internal inserts often enjoy advantages over the mentioned shapes with respect to strength of the plate heat exchanger (especially its resistance to high internal pressures) since the inserts may be metallically connected over a relatively large area to the opposite plate bottoms of the heat exchanger plates.  
         [0007]     The present invention is directed toward overcoming one or more of the problems set forth above.  
       SUMMARY OF THE INVENTION  
       [0008]     According to one aspect of the present invention, a plate heat exchanger is provided including first and second sets of heat exchanger plates. The plates of the second set are alternately stacked with the plates of the first set of plates to form flow channels therebetween. The first set of heat exchanger plates have first projections protruding in one direction from the plane of the plates and second projections protruding in the opposite direction from the plane of the plate. The second set of heat exchanger plates have third projections protruding in the one direction from the plane of the plates of the second set. The first projections are connected to the adjacent heat exchanger plate of the second set and the second projections narrow the flow channel by protruding into the space between at least two of the third projections.  
         [0009]     In one form of this aspect of the present invention, the first projections are connected to adjacent heat exchanger plates by solder.  
         [0010]     In another form of this aspect of the present invention, the first and second projections have an identical form. In an alternate form of this aspect of the present invention, the first and second projections have different configurations from one another.  
         [0011]     In still another form of this aspect of the present invention, the number, configuration and arrangement of the first and second projections are selected to optimize heat exchanger strength and heat exchange efficiency.  
         [0012]     In yet another form of this aspect of the present invention, the plates of both sets are trough-like with a protruding edge and inserted one in the other to connect on the edge.  
         [0013]     According to another form of this aspect of the present invention, the second projections are spaced from and not connected to the plates of the second set of plates.  
         [0014]     According to yet another form of this aspect of the present invention, the second protrusions are connected to the adjacent heat exchanger plate of the first set.  
         [0015]     According to still another form of this aspect of the present invention, the first projections lie against the plane of the adjacent plate of the second set of heat exchanger plates.  
         [0016]     According to another form of this aspect of the present invention, the first and second projections have the same height (h), in opposite directions, from the plate from which they protrude. According to an alternate form, the first projections have a first height in one direction from the plate, and the second projections have a second height in the opposite direction from the plate, and the first and second heights are different.  
         [0017]     According to yet another form of this aspect of the present invention, height (H) of the third projections from the second set plates is greater than the height (h) of the first and second projections from opposite sides of the first set plates.  
         [0018]     According to still another form of this aspect of the present invention, all of the plates of the first and second sets have at least four openings forming four channels through the stacked plates, two of the channels serving for feed or discharge of oil and the other two for feed or discharge of a coolant. In further forms, annular deformations are provided around the openings for selectively defining and blocking passages between the plate opening channels and the flow channels formed between the plates, and/or deflecting deformations are provided only partially around the plate openings of at least two of the plate opening channels to deflect the oil and/or coolant.  
         [0019]     According to yet another form of this aspect of the present invention, the flow channels in which the first projections protrude are provided for coolant and the other flow channels into which the second projections protrude are provided for oil. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0020]      FIG. 1  is a perspective view of a plate heat exchanger according to the present invention;  
         [0021]      FIG. 2  is one type of heat exchanger plate according to the present invention, as viewed from above;  
         [0022]      FIG. 3  is detail A from  FIG. 2 ;  
         [0023]      FIG. 4  is detail similar to  FIG. 3  for differently configured projections;  
         [0024]      FIG. 5  is the heat exchanger plate of  FIG. 2  as seen from below;  
         [0025]      FIG. 6  is detail B from  FIG. 5 ;  
         [0026]      FIG. 7  is a cross-section through stacked plates of a plate heat exchanger according to the present invention;  
         [0027]      FIG. 8  is a cross-section through another location of the plate heat exchanger;  
         [0028]      FIG. 9  is a cross-section along line  9 - 9  of  FIG. 7 ;  
         [0029]      FIG. 10  is an enlarged cross-section of stacked plates of a heat exchanger according to the present invention;  
         [0030]      FIG. 11  is an enlarged cross-section similar to  FIG. 10  but of a different plate configuration;  
         [0031]      FIG. 12  is a perspective view from above of a heat exchanger plate of the type shown in  FIG. 11 ; and  
         [0032]      FIG. 13  is a cut out portion of  FIG. 1 , showing the passages as formed through the stacked plates. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0033]      FIG. 1  illustrates a housingless plate heat exchanger  20  incorporating the present invention as may be used, for example, for cooling and/or temperature control of transmission oil by means of the engine coolant in a vehicle.  
         [0034]     The heat exchanger  20  includes stacked heat exchanger plates  22 ,  24  having four openings  26 - 29  that form four channels  30 - 33  in the plate heat exchanger, which serve to supply or discharge oil and coolant.  
         [0035]     The elements of the plate heat exchanger may advantageously be made from aluminum sheet having an expedient solder coating, and the heat exchanger plates  22 ,  24  may be advantageously produced from aluminum sheet with a sheet thickness of about 0.3 mm by means of suitable sheet deformation methods.  
         [0036]     The heat exchanger plates  22 ,  24  are designed trough-like with a continuous raised edge  36  therearound, with the stacked plates  22 ,  24  sealed around the raised edges  36  and the plate heat exchanger  20  sealed on the top by a cover plate  38  and on the bottom by a base plate  40 . The connections for the two heat exchange media may be provided in the base plate  40 , which may also function to fasten the plate heat exchanger to another element (e.g., by holes  41 ). Knobs  42  may also be provided on the base plate  40  to assist in positioning the stack of heat exchanger plates  22 ,  24  on base plate  40 .  
         [0037]     The cover plate  38  is illustrated in  FIG. 1  with cut away corners  44  to show the four channels  30 - 33 , which are covered by the cover plate  38 . Depending on the requirements of the system with which the heat exchanger  20  is used, the connections for both media that participate in heat exchange can also occur through the cover plate  38 , or other connection configurations can also be used with the present invention as will be understood by those skilled in the art.  
         [0038]      FIGS. 2 and 5  show one of the heat exchanger plates  22 . The other heat exchanger plate  24  is shown in  FIG. 12 . Both heat exchanger plates  22 ,  24  have an annular deformation  50  at the four openings  26 - 29 . In accordance with the present invention, the two types of heat exchanger plates  22 ,  24  differ with respect to the shapes or projections or protrusions from the plane  52  of the plate bottom  54 .  
         [0039]     Heat exchanger plate  22  is of special significance here. It has first projections  50  and second projections  62  that protrude in the opposite direction from the plane of the plate  52 . Roughly square or rectangular second projections  62  extend upward from the plane of the plate  52  in  FIG. 2  and roughly circular first projections  60  can be seen, which protrude downward from the plane of the plate  52  or from the plate bottom  54 . Since  FIG. 5  shows a heat exchanger plate  22  of the same type, but viewed from the bottom, the direction of the projections  60 ,  62  is opposite of that described in  FIG. 2  accordingly. This also applies for  FIG. 6 , which only shows an enlarged cut-out B from  FIG. 5 .  
         [0040]     The rectangular projections  62  have a gradation  68 , which is readily apparent from the enlarged depiction in  FIG. 11 . The gradation  68  increases the rigidity, increases the surface, and therefore contributes to increased heat exchange efficiency. As further shown in  FIGS. 7, 8  and  11 , the projections  62  constrict flow channels  72 . The configuration of the individual projections  60 ,  62  and that of projections  76  on the other heat exchanger plates  24  (see  FIGS. 7-8  and  10 - 12 ) may be selected according to the particular design purpose by one skilled in the art. For example, a variant is shown in  FIG. 4  in which all the first and second projections  60 ,  62  are circular. The projections  76  on the heat exchanger plates  24  all point in one direction (i.e., downward in the orientation of  FIGS. 7 and 8 ). The height H of the projections  76  as illustrated is advantageously greater than the height h of the projections  60  or  62 . The heights H, h determine the spacing between the plate bottoms  54  and the height of the flow channels  72  and  78  whereby, in the illustrated embodiment, one set of flow channels  72  (e.g., for oil) have a greater height H than the height h of the other flow channels  78  (e.g., for coolant). It should be appreciated, therefore, that selection of the height of the projections may readily allow different size flow channels  72 ,  78  for easy adaptation of the present invention for different applications and heat exchange media.  
         [0041]     In the depicted practical examples, the height h of the projections  60  and  62  is identical, but it should be appreciated that this is not essential to the present invention. The height h of the projections  62  in an undepicted practical example could be identical to the height H of the projections  76 , in which case the projections  62  would lie against the heat exchanger plate  24  and could be connected to it.  
         [0042]     Positioning of the individual projections  60 ,  62  in the illustrated embodiment may advantageously be in different alternating rows  80 ,  82  viewed in the longitudinal direction  84  of the plate  22 . For example, as illustrated, rows  80  that are formed only from square projections  62  and alternating rows  82  include alternating circular projections  60  and square projections  62 . The rows  80 ,  82  may advantageously be arranged as mirror images of each other relative to the center  86  of the heat exchanger plate  22 . It should be understood, however, that a different sequence and arrangement of projections  60  and  62  could also be chosen within the scope of the present invention, with optimization of the arrangement occurring by achievement of minimal pressure loss with simultaneously high heat exchange efficiency. It should further be understood that the form of the projections  60 ,  62  and  76  (e.g., round or oval, square or rectangular, elongated arc-like, with or without gradation  68 , or with more than one gradation  68 ) can also be varied from those shown in the Figures within the scope of the present invention.  
         [0043]     A number of circular projections  60  may be concentrated in the plate bottom  54  in the region  90  between openings  26 ,  27  and  28 ,  29 , as illustrated in  FIG. 2 , which circular projections  60  are connected to the plate bottoms  54  of adjacent heat exchanger plates  24  to provide particularly high internal pressure stability in the region  90  between the openings  26 - 29 . It should be understood, however, that the projections  60  could also be advantageously connected to projections (not shown) in the plate bottom  54  of an adjacent heat exchanger plate  24 .  
         [0044]     The described two types of trough-like heat exchanger plates  22 ,  24  are stacked one in the other alternately so that the flow channels  72  for oil and flow channels  78  for coolant are produced between the heat exchanger plates  22  and  24  (see  FIGS. 7 and 8 ). The oil flow channels  72  are hydraulically connected to an oil inlet channel  30  and an oil outlet channel  33  and the coolant flow channels  78  are accordingly connected to the other (coolant) inlet channel  31  and the other (coolant) outlet channel  32 .  
         [0045]     The arrows in  FIGS. 9, 10  and  11  represent possible flow directions of the two media, with the dashed arrows showing the coolant and the solid arrows showing the oil. It should be appreciated that the projections  62  protrude into a space  92  between two projections  76  and produce turbulence  94  there (see  FIG. 11 ).  
         [0046]      FIG. 9  shows a horizontal section through a part of an oil flow channel  72  of an alternate embodiment having a different arrangement of projections  60 ,  62 ,  76 . The cut passes through the projections  62  of one heat exchanger plate  22  and through the projections  76  on the other heat exchanger plate  24  (the projections  60  on the heat exchanger plate  22  appear uncut and represent a circular ring or ellipse). Turbulence  94  for the flowing oil is produced in the regions around the projections  62 , and the oil can flow linearly  96  between the projections  76  and  62 . The spacings  98  may advantageously be chosen as small as possible so that the oil undergoes the most efficient possible heat exchange with the coolant. As is apparent in  FIG. 2 , the spacing  98  can also be entirely omitted so that effective swirling (turbulence  94 ) of the oil occurs.  
         [0047]     A top view of the second type of heat exchanger plate  24  is shown in  FIG. 12 , wherein the projections  76  are regularly arranged and protrude downward from the plane of the plate  52  of the heat exchanger plate  24 . The arrangement of projections  60 ,  62  and  76  of both heat exchanger plates  22  and  24  should ideally be adapted to each other in order to guarantee optimal functioning of the heat exchanger.  
         [0048]     As can be seen from  FIGS. 2 and 12 , both types of heat exchanger plates  22 ,  24  have a partial deformation  50  at the openings  26  and  29  and an oppositely-directed annular deformation  100 . Such annular deformations  100  are also situated on the other openings  27  and  28 . Passages  102  between the supply and discharge channels  30 - 33  and the flow channels  72 ,  78  are suitably located around the channels  30 - 33 , with the partial deformations  50  serving to produce flow deflection in those corner areas of the plate heat exchanger to help ensure that the entire surface of the heat exchanger plates participate in heat exchange. This type of deformation of the heat exchanger plate on the edge of the openings was already described in the still unpublished application DE 103 48 803.0, the disclosure of which is hereby incorporated by reference. With the present application, however, only two of the four openings  26 ,  29  are provided with the partial deformations  50 . Other configuration possibilities of the partial deformation  50  can be found in DE 103 48 803.0.  
         [0049]     In accordance with the present invention, a plate heat exchanger  20  may be adapted to provide suitable strength and heat exchange efficiency for a stipulated application without having to provide internal inserts in the flow channels. As a result, good results can be achieved both in terms of internal pressure stability and heat exchange efficiency, without the contamination drawbacks potentially present when internal inserts are used.  
         [0050]     By appropriate positioning and configuration of the projections  60 ,  62 ,  76 , internal pressure stability may be achieved by the connected projections  60 ,  76  and improved heat exchange efficiency may be achieved by the projections  60 ,  62 ,  76  as well (with the projections increasing the heat-exchanging surfaces and increasing the flow rate of the medium by constricting the channel so that the mentioned improvement in heat exchange efficiency is achieved). The increase in surface available for heat exchange is achieved, for example, in the flow channel  72  by the projections  62 .  
         [0051]     Further, it should be appreciated that the elimination of inserts/turbulence plates according to the present invention allows the heat exchanger  20  to be produced more favorably in an automated process. Only two different types of heat exchanger plates need be stacked, one on the other, to provide for simplification and cost reduction in manufacturing.  
         [0052]     Still other aspects, objects, and advantages of the present invention can be obtained from a study of the specification, the drawings, and the appended claims. It should be understood, however, that the present invention could be used in alternate forms where less than all of the objects and advantages of the present invention and preferred embodiment as described above would be obtained.