Abstract:
A heat exchanger including a collecting tank and at least one flat tube row. The flat tubes have a discharge end secured to the collecting tank, a closed end, and a longitudinal separator dividing the tubes into oppositely-traversed channels, wherein at least a portion of one tube wall at the closed end and the separator associated with the tube wall portion are omitted. A closure piece closes the tubes where the tube wall portions are omitted. A partition in the collecting tank separates the inlet and outlet sides. Heat exchanger elements between the flat tubes are adapted to be traversed by a medium flowing outside the tubes. The first tube row may be connected with one end to one side of the collecting tank with a second tube row connected with its first end to another side of 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 is directed toward heat exchangers, and more particularly to vehicle coolant radiators.  
       BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE PRIOR ART  
       [0005]     A radiator for the cooling unit of an internal combustion engine of a vehicle is shown and described in DE 34 40 489 C2, and has a collecting tank divided into parts by a partition, with a series of flat tubes discharging on one end into the tank. The flat tubes are divided into oppositely traversed channels by a longitudinal separator, which terminates short of the other tube end, whereby there is flow connection between the channels in the other end of the flat tubes. Accordingly, it will be appreciated that flowing medium in one part of the collecting tank enters one channel on the tube one end, flows through that channel to the other end, then passes to the adjacent channel at that other end (where there is no channel separator), and then flows back in the opposite direction through the adjacent channel to the other part of the collecting tank. The longitudinal separator is formed as an inserted rod or as a bead in the wall of the flat tube, which was flattened a bit on the other end of the flat tube. Both the rod to be inserted and the part of the bead to be flattened are obstacles to a cost-effective manufacturing process.  
         [0006]     The present invention is directed toward overcoming one or more of the problems set forth above.  
       SUMMARY OF THE INVENTION  
       [0007]     According to one aspect of the present invention, a heat exchanger includes at least one collecting tank and at least one row of flat tubes. The flat tubes have a first end secured to the collecting tank to discharge therein, a closed second end, and at least one longitudinal separator in the tubes dividing the tubes into oppositely-traversed channels, wherein at least a portion of one tube wall at the closed second end and the separator associated with the tube wall portion are omitted. At least one closure piece closes the tubes where the portions of the one tube wall are omitted, and at least one partition in the collecting tank separates the inlet side from the outlet side. Heat exchanger elements are arranged between the flat tubes and adapted to be traversed by a medium flowing outside of the flat tubes.  
         [0008]     In one form of this aspect of the present invention, the heat exchanger is a vehicle coolant radiator.  
         [0009]     In another form of this aspect of the present invention, a common closure piece is provided for the second ends of a plurality of the tubes.  
         [0010]     In still another form of this aspect of the present invention, separate closure pieces are provided for each tube having a wall portion omitted.  
         [0011]     In yet another form of this aspect of the present invention, aligned portions of both side walls of each flat tube are omitted.  
         [0012]     According to another aspect of the present invention, a heat exchanger includes at least one collecting tank and at least two rows of flat tubes. The flat tubes have a first end secured to the collecting tank to discharge therein, a closed second end, and at least one longitudinal separator in the tubes dividing the tubes into oppositely-traversed channels. A first row of flat tubes is connected with one end to one side of the collecting tank and a second row of flat tubes is connected with its first end to another side of collecting tank. A partition in the collecting tank separates the inlet side from the outlet side; and heat exchanger elements are arranged between the flat tubes and adapted to be traversed by a medium flowing outside of the flat tubes.  
         [0013]     In one form of this aspect of the present invention, at least a portion of one tube wall at the closed second end and the separator associated with said tube wall portion are omitted, and at least one closure piece closes the tubes where the portions of the one tube wall are omitted.  
         [0014]     In another form of this aspect of the present invention, the heat exchanger is a vehicle coolant radiator.  
         [0015]     In still another form of this aspect of the present invention, the first and second rows of flat tubes lie in a common plane.  
         [0016]     In yet another form of this aspect of the present invention, the first and second rows of flat tubes are at an angle to each other.  
         [0017]     In another form of this aspect of the present invention, the flat tubes have different tube lengths (L).  
         [0018]     In still another form of this aspect of the present invention, the tube lengths (L) are different in both rows.  
         [0019]     In yet another form of this aspect of the present invention, the tube lengths (L) are the same in both rows.  
         [0020]     In another form of this aspect of the present invention, flow through the flat tubes occurs in the opposite direction in all rows of flat tubes. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0021]      FIG. 1  is a perspective view of a heat exchanger incorporating the present invention;  
         [0022]      FIG. 2  is a perspective view of a heat exchanger incorporating the present invention with two rows of flat tubes at an angle relative to each other;  
         [0023]      FIG. 3  is a perspective view of a heat exchanger incorporating the present invention with two rows of flat tubes lying in a plane;  
         [0024]      FIG. 4  is a perspective, partially broken away view of flat tubes ends with a closure piece incorporating the present invention;  
         [0025]      FIG. 5  is a perspective, partially broken away view of a first alternate of flat tubes ends with closure piece incorporating the present invention;  
         [0026]      FIG. 6  is a perspective, partially broken away view of a second alternate of a flat tubes end incorporating the present invention;  
         [0027]      FIG. 7  is a perspective, partially broken away view of a third alternate of a flat tubes end with a closure piece incorporating the present invention;  
         [0028]      FIG. 8  is a perspective, partially broken away view of a multiport flat tube end with a closure piece incorporating the present invention.  
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0029]     The Figures illustrate different variants of air-cooled coolant radiators which may be advantageously produced completely from aluminum. The coolant, according to the arrows C (see, e.g.,  FIG. 1 , flows through flat tubes  10 . Cooling air flows across the flat tubes  10  through heat exchanger elements (corrugated ribs)  12  between and in heat-conducting connection with the flat tubes  10  (the corrugated ribs  12  are not shown in  FIG. 1  but are indicated in  FIG. 4 ) as indicated by arrow A in  FIG. 1 .  
         [0030]     The heat exchanger according to  FIG. 1  includes a collecting tank  20  with a partition  22  (indicated by a dashed line) separating the collecting tank  20  into an inlet side  24  and an outlet side  26 . A collecting tank inlet  30  is on the inlet side  24  and a collecting tank outlet  32  is on the outlet side  26 .  
         [0031]     It should be appreciated that it would be within the scope of the present invention for there to be, for example, two directly adjacent or connected collecting tanks (with, e.g., an inlet tank and an outlet tank). Further, it would be within the scope of the invention, depending upon the requirements of a particular application, to include more than one partition in the collecting tank(s).  
         [0032]     A single row of flat tubes  10  with corrugated ribs  12  is shown in  FIG. 1 . The flat tubes  10  are connected with one end  40  tightly to the collecting tank  20  so that the coolant can flow as described. The flat tubes  10  each have a longitudinal separator  46  (indicated by a dashed line in  FIGS. 1-3 ) which divides the flat tubes  10  into two oppositely traversed channels  50  and  52 . The partition  22  in the collecting tank  20  is positioned to be aligned with the position of the longitudinal separator  46  so that opposite flow is established between the channels  50 ,  52 .  
         [0033]     The flat tubes  10  can, for example, be advantageously produced from an endless sheet of metal which is shaped and soldered or welded, where the longitudinal separator  46  is formed by the longitudinal edges of the sheet metal, where the longitudinal edges are in contact roughly in the center of the flat tube and there form the longitudinal separator  46 . It should be appreciated, however that advantages of the present invention could be obtained with a variety manufacturing methods used to form the basic tubes, including manufacturing of flat tubes in which several channels per flow direction and several longitudinal separators are provided.  
         [0034]     Advantageous formation of the other tube ends  54  (remote from the collecting tank  20 ) is shown in  FIGS. 4-8 , where a cut-out  60  is formed in at least one of the broad flat walls  64  of the flat tubes  10 . The longitudinal separator  46  is also removed in the region of the cut-out  60  and a closure piece  70  closes the cut-out  60  that end of the tube  10 , and as a result the channels  50 ,  52  are not separated in that area and the coolant can pass from the one channel  50  to the other channel  52  for return flow as previously described.  
         [0035]     Manufacture of tubes  10  according to this aspect of the invention can be advantageously accomplished by first forming tubes stock, either continuously or at desired lengths, then cutting tubes from the tube stock to the desired length, including forming cut-outs  60  at one end  54  such as described herein, then adding the closure piece(s)  70  while assembling the tubes  10  with the collecting tank  20 .  
         [0036]     The advantageous cut-out  60  according to the present invention may be formed in a variety of ways and configurations.  
         [0037]     The cut-out  60  in the embodiment illustrated in  FIG. 4  is a semicircular shape extending through both broad walls  64  of the flat tubes  10 . A single closure piece  70  is provided for all the flat tube ends  54 , with the illustrated closure piece  70  being advantageously formed as a single deformed sheet strip whose width corresponds to that of flat tubes  10 , with the sheet strip having a meandering configuration with a plurality of bevelings which correspond to the spacings of the individual flat tubes  10  and the depth of cut-out  60 . Directed embossings (not shown) may also be advantageously provided at the flat tube ends  54  whereby each embossing fits into the end  54  of the flat tube  10  in order to improve tightness of the connection there.  
         [0038]     In the embodiment shown in  FIG. 5 , the cut-out is provided in only one broad side  64  of the flat tube ends  54 , with the flat tubes  10  being arranged so that two cut-outs  60   a  are always opposite each other. Such cut-outs  60   a  can be advantageously closed with a roughly U-shaped closure piece  70   a  inserted in the spacing between two flat tube ends  54 . The cut-outs  60   a  are designed there so that a connector is still included in the broad side  64  that has the cut-out  60 , right on the end  54  of flat tube  10 .  
         [0039]     Other embodiments are shown in  FIGS. 6-8 , in which both broad sides  64  of each flat tube  10  are cut out and each flat tube end  54  has assigned its own closure piece  70 ′, which is shaped accordingly.  
         [0040]      FIG. 8  shows the tube end  54  of a multichamber flat tube  10  with a plurality of channels  50   a ,  52   a  defined thereby (and advantageously produced, for example, by an extrusion method), with the cut-out  60   b  according to another embodiment of the present invention advantageously roughly triangular and a width bridging connector left on the end  54  there as well.  
         [0041]     Two heat exchangers are shown in  FIGS. 2 and 3  with flat tubes  10  and flat tube ends  54  are formed as described. It should be appreciated from these figures, and the rest of the disclosure, that a different configuration of flat tube ends  54  could be provided within the scope of the present invention  
         [0042]     Moreover,  FIGS. 2 and 3  show heat exchangers having two rows of flat tubes  10  connected with one end  40  to opposite sides  20   a ,  20   b  of the collecting tank  20  so that the already-described flow of the heat transfer agent (as indicated by the arrows) is established in conjunction with the partition  22  in collecting tank  20 . The tube lengths L increase continuously in those rows so that, in two diagonally opposite corner regions of the heat exchanger, the longest flat tubes  10  are provided and in the other two corner regions the shortest flat tubes  10  are present, as both figures show. As a result, heat exchangers according to this feature of the present invention may be readily manufactured with a front surface having a configuration deviating from the usual rectangle or square. For example, a front surface configuration can be achieved in which the round or U-shape of the opening fits into a fan hood. As a result, it is possible to provide heat exchangers which can be more simply adapted to different space requirements such as may be encountered in different vehicles.  
         [0043]     The difference between  FIGS. 2 and 3  is that the  FIG. 2  heat exchanger has a collecting tank  20  with a roughly triangular cross-section (rather than rectangular) so that the two rows of flat tubes  10  and the heat exchanger elements  12  are at a corresponding angle to each other (in  FIG. 3 , by contrast, both rows lie in a common plane). Depending on the space requirements, for example, beneath the hood of a particular vehicle, such shape may allow for better utilization of the space.  
         [0044]     Moreover, it should be appreciated that while the formation of the tubes by use of cut-outs  60  such as previously described could be advantageously used with heat exchangers such as shown in  FIGS. 2-3 , advantages of the  FIGS. 2-3  structure (with tube rows extending from two sides of the collecting tank  20 ) could still be achieved by alternatively closing the other tube ends  54  by simply turning back the ends, squeezing them broadly and then tightly soldering them later.  
         [0045]     It should also be appreciated that these are only practical examples intended to illustrate that different forms of the heat exchanger are possible by the simple expedient of providing different tube lengths L, and variants having a heat exchanger shape that differs significantly from  FIGS. 2 and 3  could also fall within the scope of the present invention. Moreover, continuous increase or decrease of the tube lengths is not required, as it would be possible in the scope of the present invention to provide tubes in the same row which are longer and then shorter, and in which the amount of increase or decrease from tube to tube need not be identical, as shown in  FIGS. 2 and 3 .  
         [0046]     It should further be appreciated that the tubes requiring passage between the channels  50 ,  52  at the outer end  54  may be relatively simply and efficiently produced by use of cut-outs  60  as described. For example, production of cut-outs is simpler than flattening of the bead such as was done in the prior art. This is especially true when the flat tubes are extremely flat (free width 1 mm or less), as often used, for example, with vehicle engine radiators. Moreover, production of the cut-outs  60  can be readily and efficiently accomplished simultaneously with cutting off lengths of the endlessly produced flat tubes.  
         [0047]     Moreover, it should be appreciated that heat exchangers according to the invention promises excellent heat exchange efficiency, because heat exchange according to the cross-counterflow principle is provided. That is, the coolant flows in a channel  50  within the flat tubes  10  and flows back in a parallel channel  52  of the flat tube  10  in counter-current, and cooling air flows across the flat tubes  10  between them and through the heat exchange elements (corrugated ribs)  12 .  
         [0048]     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.