Abstract:
A heat exchanger including a collecting tank having an outwardly extending flange around an edge, a tube plate having a connection edge, tubes having ends extending into openings in the tube plate, and an intermediate plate having an edge lying against the connection edge of the tube plate. The connection edges of the intermediate plate and the tube plate are both mechanically connected to the flange of the collecting tank. Pins in the corners of one of the tube plate and the intermediate plate secure the tube plate and intermediate plate together. The connection edge of the plates include protrusions bendable onto the edge flange of the collecting tank.

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 heat exchangers, and more particularly to heat exchangers having tubes secured to a tube plate connected along its edge to a collecting tank, and a method of producing such heat exchanger.  
       BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE PRIOR ART  
       [0005]     Heat exchangers having tubes and ribs forming a core, in which a first medium (e.g., coolant) flows through the tubes and a second medium (e.g., environmental air) passes over the ribs for heat exchange between the two media are well known. Also well known are the use of collecting tanks with such cores, where the collecting tanks are secured to the ends of the tubes to distribute medium flow to the tubes (at the inlet end) and collect medium from the tubes (at the outlet end).  
         [0006]     Such heat exchangers have been subjected to a variety of design alternatives intended to address a variety of concerns and issues. For example, minimizing materials is a desirable goal in the manufacture of most heat exchangers (e.g., to minimize costs), and is particularly so with vehicular heat exchangers where component weight is an important consideration. As another example, EP 1 273 864 A2 discloses a heat exchanger in which an intermediate plate is provided so that a heat exchanger with cooling grates of different depths may be made at a relatively low modification cost. However, it has been found that, in such structures, the reduction in materials (and related reduction in sheet thickness) can result in a heat exchanger in which the connection and holding forces may not be sufficient to withstand the increasing pressures and other loads to which the heat exchanger may be subjected.  
         [0007]     The present invention is directed toward overcoming one or more of the problems set forth above.  
       SUMMARY OF THE INVENTION  
       [0008]     In one aspect of the present invention, a heat exchanger is providing including a collecting tank having an outwardly extending flange around an edge, a tube plate having a connection edge, tubes having ends extending into openings in the tube plate, and an intermediate plate having an edge lying against the connection edge of the tube plate. The connection edges of the intermediate plate and the tube plate are both mechanically connected to the flange of the collecting tank.  
         [0009]     In one form of this aspect of the present invention, the intermediate plate lies in the tube plate.  
         [0010]     In another form of this aspect of the present invention, the tube plate lies in the intermediate plate.  
         [0011]     In still another form of this aspect of the present invention, pins are in the corners of one of the tube plate and the intermediate plate, and the pins secure the tube plate and intermediate plate together.  
         [0012]     In yet another form of this aspect of the present invention, the connection edge of the intermediate plate and the connection edge of the tube plate comprise of a plurality of protrusions bendable onto the edge flange of the collecting tank. In a further form, beads are provided in the protrusions.  
         [0013]     In a further form of this aspect of the present invention, indentations are provided in the connection edges of the intermediate plate and the tube plate, with the indentations generally parallel to the plane of tube plate deformable inward onto the tank flange to define a generally wave-like trend of the connection edges. In one further form, the indentations are congruent relative to each other on the connection edges. In another further form, the indentations are offset relative to each other on the connection edges.  
         [0014]     In another form of this aspect of the present invention, perforations are provided in the connection edges of at least one of the tube plate and the intermediate plate, and protrusions on the tank edge flange are received in the perforations.  
         [0015]     In another aspect of the present invention, a method of producing a heat exchanger is provided, including the steps of (a) assembling a heat exchanger core of the flat tubes and ribs, (b) mounting a tube plate and an intermediate plate on the ends of the flat tubes, (c) metallically joining the tubes, ribs, tube plate and intermediate plate into a unit, and (d) mechanically connecting a collecting tank to the tube plate and the intermediate plate by deforming both of the tube and intermediate plates.  
         [0016]     In one form of this aspect of the present invention, the tube plate and the intermediate plate are deformed simultaneously in the mechanically connecting step. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a perspective view of a partially produced heat exchanger according to the present invention;  
         [0018]      FIG. 2  is a perspective view of the tube plate of  FIG. 1 ;  
         [0019]      FIG. 3  is a perspective view of the intermediate plate of  FIG. 1 ;  
         [0020]      FIG. 4  is a perspective view similar to  FIG. 1 , but showing a collecting tank installed thereon;  
         [0021]      FIG. 5  is a side view of the assembly of  FIG. 4 ;  
         [0022]      FIG. 6  is a longitudinal cross-sectional view through the heat exchanger of  FIGS. 1-5 ;  
         [0023]      FIG. 7  is a perspective view of a portion of the assembly showing a detailed view of clamping of the plates and collecting tank;  
         [0024]      FIG. 8  is a perspective view illustrating the connection of a collecting tank to tube and intermediate plates according to a second embodiment of the present invention;  
         [0025]      FIG. 9  is a perspective view of a variation of the  FIG. 8  embodiment.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0026]     The present invention relates to a heat exchanger  20 , for example, a charge air cooler or a coolant radiator, situated in a vehicle. For simplicity of illustration, the collecting tank  22  on only one side of the heat exchanger  20  is illustrated, though it should be understood that the other side may be identical at least in terms of the design of interest here. As is understood by those skilled in the art, cooling air usually flows through heat exchanger ribs  26 , for example corrugated ribs, removing heat from the other medium which flows in tubes  28  via a collecting tank  22 . As is understood by those skilled in the art, the ribs  26  and tubes  28  may be advantageously assembled to form a heat exchanger core during assembly of the heat exchanger  20   
         [0027]     The heat exchanger  20  depicted in  FIG. 1  is situated, in principle, in the state in which it is present after leaving a soldering furnace. In this condition, the connection edge  30  on the intermediate plate  34  and the connection edge  40  on the tube plate  44  are already deformed. Initially, however, the edges  30  and  40  are almost vertical relative to the plane of tube plate  44 , whereby the collecting tank  22  may be positioned on the plates  34 ,  44  as described below, with the edges  30 ,  40  only acquiring the bent shape depicted in  FIG. 1  after positioning and mechanical connection of the collecting tank  22  (see  FIG. 4 ).  
         [0028]     After insertion of a suitable seal (not shown) and mounting of the collecting tank  22 , both the parts (tabs) of the edge  30  of the intermediate plate  34  and the parts of the tube plate edge  40  may be advantageously deformed in a machine tool so that, in this practical example, they are bent downward onto the outwardly projecting flange or bulge  50  around the edge of the collecting tank  22 , so that the edges  30 ,  40  of both the intermediate plate  34  and the tube plate  44  together serve to hold the collecting tank  22  thereon. Bending deformation of both plates  34 ,  44  may advantageously be accomplished simultaneously.  
         [0029]     In the depicted practical example, the intermediate plate  34  lies in tube plate  44 , with the edge  54  of intermediate plate  34  lying inside the connection edge  40  of tube plate  44 , and may be advantageously soldered therein. It should be appreciated that the components may advantageously be aluminum such as is generally known in the art.  
         [0030]     The depicted intermediate plate  34  has two transverse struts  60 . The struts  60 , and are positioned so as to each lie between two tube openings  64  in the tube plate  44 . The struts  60  may be advantageously soldered to the tube plate  44  between tube openings  64 .  
         [0031]      FIG. 2  shows a tube plate  44  as used in the illustrated practical example, and  FIG. 3  shows an intermediate plate  34  from the same perspective. Since, as already mentioned, the intermediate plate  34  lies in the tube plate  44  in this practical example, the tabs on the connection edge  40  of tube plate  44  are somewhat longer than the tabs on the connection edge  30  of intermediate plate  34 , as can easily be seen from a comparison of  FIGS. 2 and 3 , whereby both sets of tabs may readily clamp onto the flange  50  of the collecting tank  22 . Further, the numbers, size and arrangement of tabs on both edges  40 ,  30  may be different, as also can easily be seen from a comparison of  FIGS. 2 and 3 .  
         [0032]     The tabs on both edges  40 ,  30  lie one above the other in the depicted practical example, as can be clearly seen from  FIGS. 1 and 4 .  
         [0033]     It should therefore be appreciated that there is latitude in terms of different configurations for such tabs for different practical examples. For example, it can be advantageous to deform the tabs successively rather than simultaneously (e.g., initially the tabs of the tube plate  44  may be deformed (preferably in one working step), and then the tabs of intermediate plate  34  (also in one working step), or vice versa, with the tabs of the intermediate plate  34  first deformed and then the tabs of the tube plate  44 .  
         [0034]     Additional aspects of the present invention are depicted in  FIG. 6 . For example, it is apparent from the longitudinal section through the heat exchanger  20  that the tube openings  64  in the tube plate  44  are equipped with particularly long passages  66  reduced in thickness, which are directed toward ribs  26 . The ends of the tubes  28  are soldered to the passages of  66  and do not extend beyond the internal tube plate surface. This design is favorable because the pressure loss is kept low on this account.  
         [0035]      FIGS. 2 and 7  show pins  70  in the corners of the tube plate  44 , which pins  70  serve to pre-fasten the intermediate plate  34  to the tube plate. Beads  74  can be formed in the tabs to improve rigidity and holding properties. Perforations  78  are also provided in the intermediate plate  34  into which protrusions  80  molded on the edge bulge  50  of the collecting tank  22  engage in order to secure the collecting tank  22  before its mechanical connection by the tabs, and also to force it firmly onto the seal (not shown).  
         [0036]      FIGS. 8 and 9  show different variants with a corrugated trend on the connection edges  40  and  30 . The sections deformed on the edge bulge  50  of the collecting tank  22  in  FIG. 9  are divided (see reference number  88 ) perpendicular above the indentations  84  of the connection edges. In both Figures, the trend of the corrugations (indentations  84 ) on the connection edge of intermediate plate  34  is congruent with the trend of the corrugations on the connection edge of tube plate  44 .  
         [0037]     It should thus be appreciated that the disclosed invention provides an excellent compromise between low material use and an increase in connection strength. The intermediate plate  34  is an additional component, but one of relatively limited weight, since only a frame-like part is involved. Because of the “doubled” connection (by which is meant both a connection in which protruding tabs or similar parts of the edge of the tube plate and similar parts of the intermediate plate lie one above the other, and also those in which the mentioned parts lie next to each other), a way to further reduce sheet thickness of the tube plate  44  has been demonstrated in which the connection and holding forces are guaranteed despite the limited sheet thickness of the tube plate  44 . Heat exchangers  20  can also be provided in which the protrusion of the tube plate  44  beyond the periphery of the tubes  28  is relatively small. A compact arrangement of the heat exchanger, for example in a heat exchanger module, is therefore possible, in which several heat exchangers can be arranged one against the other.  
         [0038]     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.