Abstract:
A heat exchanger according to some embodiments includes heat exchanger plates stacked one inside the other and each having a trough-shaped edge, flow ducts located between the heat exchanger plates for heat-exchanging media, feed ducts and discharge ducts, and an attachment plate having openings for feeding and discharging the media through the attachment plate. In some embodiments, a multipart attachment plate is provided, wherein a bottom heat exchanger plate lies on an attachment plate, and another overlying attachment plate has a cutout having an edge shaped to lie against the trough-shaped edge of the bottom heat exchanger plate.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
       [0001]     Priority is hereby claimed to German Patent App. No. 10 2006 022 445.0 filed on May 13, 2006, the entire contents of which are incorporated herein by reference.  
       BACKGROUND  
       [0002]     German patent application DE 10 2004 003 790 A1 discloses a heat exchanger/oil cooler with a relatively thick base plate which is hollowed out in a trough shape in complex processing steps. The heat exchanger is inserted into this hollow shape, and then soldered to the base plate. This measure serves to avoid fractures in edge regions of the bottom heat exchanger plate due to thermal and mechanical stresses.  
         [0003]     Furthermore, Japanese patent application JP 02-691155 discloses various options for strengthening the bottom plate of a heat exchanger. In addition to a stable base plate (such as that described above) provided with a trough shape in which a bottom heat exchanger plate is seated, strips are applied from the outside, and extend on the base plate and around the circumference of the bottom heat exchanger plate.  
         [0004]     The two publications described above show relatively complex designs for reinforcement of bottom heat exchanger plates against the formation of fractures.  
       SUMMARY  
       [0005]     Some embodiments of the present invention provide alternative, manufacturing-friendly solutions for heat exchangers having lower heat exchanger plates resistant to thermal and mechanical stresses.  
         [0006]     In some embodiments, a multipart heat exchanger attachment plate is provided, wherein a bottom heat exchanger plate lies on an attachment plate and an attachment plate which is arranged above it has a cutout having an edge shaped to lie against the trough-shaped edge of the bottom heat exchanger plate.  
         [0007]     In some embodiments, the edge of the cutout has a bending angle which corresponds to the angle of the trough-shaped edge of the bottom heat exchanger plate. The angle of the trough-shaped edge can be approximately 8 to 15°. The bending angle of the edge of the cutout can therefore exceed 90°, and in some embodiments is approximately 98 to 105°. The shaping of the edge can be made easier if the corners of the cutout are indented or cut out. In some embodiments, the attachment plate is embodied in three parts. In light of the design feature disclosed herein, it is possible to provide an attachment plate having an overall thickness no greater than that found in the prior art. Nevertheless, the thickness of each part of the attachment plate can be significantly greater than the thickness of the heat exchanger plates.  
         [0008]     Also in some embodiments, the top attachment plate can have the cutout, and the attachment plates which are arranged below it can be formed in such a way that they are suitable for receiving seals.  
         [0009]     Parts of the attachment plates can have marks so that they can be assembled more easily. Parts of the attachment plates can also have matching holes in order to be able to mount the heat exchanger.  
         [0010]     In some embodiments, a seal is clamped between a bent-over opening edge of one attachment plate and a planar opening edge of another attachment plate. The seal can be placed under a degree of pre-stress so that the seal does not drop out of its position in the course of mounting. These measures can improve the ease of heat exchanger mounting.  
         [0011]     In some embodiments, the cutout is smaller than the base surface of the heat exchanger plate before the shaping of the edge is carried out. The cutout and the base surface of the heat exchanger can, for example, be embodied as rectangles, with the four sides of the edge of the cutout running parallel to the four sides of the base surface.  
         [0012]     Further advantages and features of the present invention (e.g., reduced materials) will be apparent from the following description and accompanying drawings. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0013]     Various features of the present invention are described with reference to exemplary embodiments shown in  FIGS. 1-5 , wherein:  
         [0014]      FIG. 1  shows a section through the lower region of a heat exchanger;  
         [0015]      FIG. 2  shows a partial section through a heat exchanger of another exemplary embodiment;  
         [0016]      FIG. 3  shows a plan view of an attachment plate used in FIGS.  1  or  2 ;  
         [0017]      FIG. 4  shows another a plan view of the attachment plate of  FIG. 3 ; and  
         [0018]      FIG. 5  shows a view of the attachment plate opening shown in  FIG. 2 , viewed in the direction of the arrow in  FIG. 2 . 
     
    
     DETAILED DESCRIPTION  
       [0019]      FIG. 1  shows a lower region of a heat exchanger  1 , which is presented by way of example only as an oil cooler. The illustrated heat exchanger  1  is composed of a number of trough-shaped heat exchanger plates  10  which are stacked one inside the other. The heat exchanger plates  10  bear against one another at their outer edges  11  to form the heat exchanger  1 , which is sealed by soldering or brazing. Alternating flow ducts  5  for two mediums flowing through the heat exchanger  1  are defined between the heat exchanger plates  10 , which are shaped to define the flow ducts  5 . In the flow ducts  5  it is possible, as is shown here, to provide turbulence inserts  6  for improved heat exchange, or to provide other elements or structure (not shown) for generating turbulence. In operation, media passes through the openings  21  in a part  3  of an attachment plate, and flows into and out of the heat exchanger  1  through feed ducts  22  and discharge ducts  20  (see arrows in  FIG. 1 ). The media can also flow into and out of the heat exchanger  1  through connectors (not shown) so that four openings  21  are provided in the part  3  of the attachment plate if both media are conducted through the attachment plate  3 . It should be noted that it is also possible to provide any other type of heat exchanger attached to a housing or engine block in a similar way. For example, it is possible to use screwed connections  30  passing through one or more attachment plates  3  (see  FIG. 1 ) for the attachment process.  
         [0020]     The number and positions of openings  21  in the attachment plate  3  are adapted according to requirements of the heat exchanger.  
         [0021]     A higher likelihood of fractures often exists at the edge  11  of the bottom-most heat exchanger plate  10  due to thermal and mechanical stresses of the heat exchanger  1  during its use in a motor vehicle (for example). In order to avoid this, a cutout  26  is punched into an attachment plate  2  during its manufacture, and the edge  25  of the cutout  26  is bent over subsequently or simultaneously. The edge  25  of the cutout  26  can be bent in such a way that its end  27  covers to a greater or lesser extent approximately half of the edge  11  of the bottom-most heat exchanger plate  10 , and bears directly against it. A bending radius for the edge  25  of approximately 98 to 105° can be produced, since the edge  11  of each heat exchanger plate  10  is bent outward away from a vertical orientation by approximately 8 to 15°. This reinforcement configuration at the bottom-most heat exchanger plate  10  (in region A of  FIG. 1 ) can avoid stress fractures. At the same time, in this way it is possible to reduce the consumption of material without reducing the ability of the heat exchanger and heat exchanger mounting structure to withstand stress. In fact, the ability to withstand such stress can even be improved which achieving this material savings.  
         [0022]      FIG. 2  shows another exemplary embodiment of the heat exchanger  1 . Here, a three-part attachment plate is used, and includes parts  2 ,  3 , and  4 . Parts  2  and  3  can define seal receptacles at the openings  21 , such as are described, for example, in patent application number DE 10 2006 005 084). With reference also to  FIG. 5 , in order to clamp the seal  41  tightly so that it does not drop out while the oil cooler  1  is being mounted, the opening  21  in the part  3  of the attachment plate can be, on the one hand, formed here in a corrugated shape, and on the other hand the opening  21  in the part  2  can be shaped to at least partially receive the seal  41  (e.g., by a nested relationship with the seal  41  and/or by a rolled shape  40  in which the seal  41  is received). In some embodiments, significant advantage can be obtained through the combination of the secured or retained seal  41  (e.g., by means of the particular shape  40  of the attachment plate) and reinforcement of the edge  11  of the bottom-most heat exchanger plate  10  by the bent-over edge  25  of the cutout  26  of the attachment plate part  4 .  
         [0023]     The individual parts  2 ,  3 ,  4  of the attachment plate can be manufactured from sheet metal plates of equal thickness or from sheet metal plates of different thicknesses. Overall, all the attachment plates  2 ,  3 ,  4  together can have a smaller thickness D in the region underneath the heat exchanger  1  compared to structures in the prior art, and in the rest of the region B can be equally thick (if desired). The parts  2  or  4  of the attachment plate can have a greater thickness than conventional heat exchanger plates in order to bring about particularly advantageous reinforcement. After bending over the edge  25  of the attachment plate  4 , it may also be advantageous to improve the bearing of the edge  25  of the attachment plate cutout  26  against the edge  11  of the heat exchanger plate  10  in the bend  28  by post-processing, such as by notching or other operations.  
         [0024]      FIG. 3  shows a plan view of the part  2  or  4  of either attachment plate shown in  FIGS. 1 and 2 . Part  2  or  4  of the attachment plate can have the appearance shown in  FIG. 3  after the cutout  26  has been punched or made in any other manner. In order to avoid fractures in the corners  52  of the cutout  26  during shaping of the edge  25 , the corners  52  can each be provided with an indent, notch, cut, or corner cutout  50  (collectively referred to herein as a “cutout”). When the edge  25  is bent over or deep drawn in some embodiments, a region  51  can be produced at the corners  52  of the cutout  26 , at which region  51  an edge  25  of the cutout  26  does not bear on the edge  11  of the bottom heat exchanger plate  10  (see  FIG. 4 ). However, depending on the requirements of the heat exchanger or environment, it is also possible to dispense with the cutouts  50 , whereby a smaller material thickness can be obtained at the corners  52  than at the side edges  53  (not shown). Holes  30  can be formed in all the parts  2 ,  3 ,  4  of the attachment plate to serve as engine block or housing attachment locations for the completely soldered heat exchanger  1 .  
         [0025]     In some embodiments, all the parts  2 ,  3 ,  4  of the attachment plate have marks in order to facilitate the mounting process.