Abstract:
A method for producing a heat exchanger for a motor vehicle, wherein the heat exchanger has reservoirs and a bundle of flow-through fluid conduits for guiding the flow between the reservoirs. The conduits are produced together as a bundle. A heat exchanger for a motor vehicle, especially a micro-channel cooler, can be produced by this method.

Description:
CROSS-REFERENCES TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of German Patent Application, Serial No. 10 2012 020 882.0, filed Oct. 24, 2012, pursuant to 35 U.S.C. 119(a)-(d), the content of which is incorporated herein by reference in its entirety as if fully set forth herein. 
       BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to a method for producing a heat exchanger for a motor vehicle, the heat exchanger having reservoirs and a bundle of flow-through fluid conduits for guiding a flow between the reservoirs, and a heat exchanger for a motor vehicle, especially a micro-channel cooler, produced by such method. 
         [0003]    It would be desirable and advantageous to provide an improved method for manufacturing a heat exchanger with a significantly improved performance and higher cooling capacity. It would also be desirable and advantageous to provide a heat exchanger with improved performance and enhanced cooling capacity. 
       SUMMARY OF THE INVENTION 
       [0004]    According to one aspect of the present invention, in a method for producing a heat exchanger for a motor vehicle, the heat exchanger includes a reservoir and bundle of flow-through fluid conduits for guiding a flow between the reservoirs, wherein the conduits are commonly produced as a bundle. 
         [0005]    According to another aspect of the invention, a heat exchanger for a motor vehicle can be produced with the aforedescribed method, in particular for use in a micro-channel cooler. The heat exchanger may be formed as a cross-flow, co-flow or counter-flow heat exchanger. Heat dissipation can be thereby be optimally configured depending on the application site. Primary-water and low-temperature-loop coolers can be integrated in the heat exchanger by separating different regions of the heat exchanger to save space. 
         [0006]    Thermal energy can be transferred in the heat exchanger from one medium to another medium. Both media may here be a gas, or one medium may be a gas and the other medium a liquid. Energy may also be transferred in the heat exchanger from a gaseous medium to a medium which is a gas/a liquid at a phase transition. Furthermore, both media flowing in the heat exchanger may be liquid. 
         [0007]    The two media can flow past each other in the heat exchanger so that heat is transferred between the media. In this case, one medium may be heated or cooled by the other medium. The media may be routed in the conduits guiding the flow side-by-side in opposite directions (counterflow) between the reservoirs. In the conduits guiding the flow, the media may be guided along each other between the reservoirs in the same direction (co-flow). In the conduits guiding the flow, the media may be guided along each other between the reservoirs in a cross-flow pattern. The temperatures of the two media may thus be equalized and thereafter lie between the respective initial temperatures of the different media. 
         [0008]    By increasing the surface area of the flow-through fluid conduits by arranging conduit bundles, the magnitude of the heat transfer between the media can be significantly increased. The cold medium can thus be strongly heated and the initially hot medium may be cooled as much as possible. The flow-through fluid conduits may be made of metal, enamel, plastic, glass or other materials, for example silicon carbide. Conduits made of copper or aluminum can combine good thermal conductivity with low weight. To increase the durability of the material, conduits made of steel, in particular stainless steel or cast iron may be used. To further increase the surface area of the cooling surfaces in the heat exchanger, fins, ribs or lamellae can be eliminated. Instead, the invention provides a bundle of flow-through fluid conduits for guiding the flow between the reservoirs. 
         [0009]    The conduits may include a plurality of thin-walled hollow profiles, such as tubes, with an inner diameter of less than 2 mm, in particular is less than 1 mm. The wall thickness of the conduit may be less than 1 mm, in particular less than 0.5 mm. 
         [0010]    The conduit bundle may include a plurality of hollow thin-walled profiles which are arranged in specific patterns, thereby increasing the surface area of the heat exchanger. The conduits may have a round cross-section. The cross section of each individual conduit may be non-circular, polygonal, elliptical, or may have other geometrical shapes. By the producing the conduits in form of a bundle, the conduits can be produced in the standard lengths, with standard diameter and/or standard wall thickness. A standard production process can significantly reduce the manufacturing costs. 
         [0011]    With the method according to the invention, the number of conduits within the standard bundle may be matched to the engine size. The manufacturing cost can be reduced and the production time can be shortened. Other subsequent manufacturing steps may be eliminated, thus reducing costs. The conduits in the bundle can be sealed in a single process step, mechanically cleaned, and prepared together for connection to the respective reservoirs. The further treatment of the conduits and the preparation for use in motor vehicles can be made on all conduits in the bundle repeatably and simultaneously. In this way, sequential, time-consuming steps can be eliminated. 
         [0012]    The conduits can be manufactured by an extrusion process or by injection molding. In the extrusion process, the conduits can be continuous pressed in form of a bundle from a curable material under pressure out of a shaping die. In an explosive process, the wall thickness, the diameter of the conduit and the length of the conduit can be set as required. The conduits may be prepared by a cold extrusion process under relatively low pressures and at relatively low temperatures and low shear forces. The method can also produce bundle of flow-through fluid conduits as a hot-extrusion process under high pressures and at high temperatures. The conduit bundles may be produced using piston extruders and screw extruders. Conduit bundles having complex shapes may be made from a brittle and/or soft material using the extrusion process. 
         [0013]    Conduit bundles can be economically manufactured in a particularly efficient using injection molding. The quality of the mold determines the form and surface structure of the conduit bundle, Injection molding enables the production of precise mass-produced conduit bundles with high accuracy in a short time. The production of conduit bundles by an injection molding process can be economically useful especially for large numbers. Individual conduits of the bundle can be threaded and/or inserted into components having openings. 
         [0014]    The heat exchanger may include support plates for the conduits. The support plates can be manufactured by an injection molding together with the conduits and/or connected to the conduits. The support plates can space the conduits in the bundle apart with extreme accuracy. The conduit bundle can be additionally reinforced by at least one support plate. The method enables a tight fit of the backing plate to the individual conduits of the conduit bundle. Additional costly and labor-intensive processing steps subsequent to the introduction of the individual conduits in the openings of the support plate are not required. A subsequent labor-intensive adjustment and positioning of the support plate on the conduit bundle can be omitted. 
         [0015]    The conduits can be initially produced with the support plates with arbitrary lengths and subsequently be cut to size. The pipes can be produced at low cost in an automated manufacturing process. The conduit bundle can be produced together with the support plates as a standard component. Depending on the required length of conduits, the produced lengths can be shortened to the required size. The individual conduits can be aligned on the support plates in one production step. The support plates may have devices for anchoring the conduit bundle on the vehicle. 
         [0016]    The reservoirs and/or the support plates can be materially connected with the conduits for guiding the flow during or after the production of the conduit bundles. The material connection can be performed depending on the temperature of the medium and/or depending on the type of the material of the conduit by adhesive bonding, soldering, welding and/or molding. The reservoirs, in particular distribution boxes, can be bonded, brazed, welded or molded during or after the production process. The molding can be done directly or indirectly. The material connection may also be accomplished by injection. Depending on the temperature required to manufacture the conduit bundle, the conduits are further connected to the support plates and/or the reservoirs during or only after the manufacture of the conduits. 
         [0017]    The conduits may be produced by internal high-pressure forming (hydroforming) of a preformed semi-finished product. The hydroforming process can be used to form metallic hollow profiles into conduit bundles in a closed mold by way of internal pressure. The internal pressure can be introduced into the tool or in the conduits of the bundle, for example, by a water-oil emulsion. Hydroforming offers the greatest possible design freedom in the production of the conduit bundles. The conduit bundle can also be combined during production with the reservoir and/or the support plates. 
         [0018]    With this method, additional components can be eliminated, making the production of the conduit bundle very cost-effective. Additional installation and/or welding operations can be eliminated. The hydroforming process is suitable for the production of the conduit bundles, since the process is characterized by high accuracy and repeatability in the production of the components. The semi-finished products can be preformed as standard parts. Hydroforming of the semi-finished product and manufacture of the mold required for the production of the heat exchanger can be performed in a single manufacturing step. Additional joints between conduit bundles and the distribution boxes and/or the reservoirs and/or the support plates can be omitted. 
         [0019]    The pipes can be produced together with the reservoirs in the same hydroforming process. This allows a particularly economical and resource-saving production method. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
         [0020]    Other features and advantages of the present invention will be more readily apparent upon reading the following description of currently preferred exemplified embodiments of the invention with reference to the accompanying drawing, in which: 
           [0021]      FIG. 1  shows a cooler with a heat exchanger according to the present invention, 
           [0022]      FIG. 2  shows a detail A of the heat exchanger from  FIG. 1 , 
           [0023]      FIG. 3  shows a cooler with a heat exchanger in a front view, 
           [0024]      FIG. 4  shows a section B-B through the cooler with heat exchanger according to  FIG. 3 , and 
           [0025]      FIG. 5  shows a detailed section C of  FIG. 4 . 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0026]    Throughout all the figures, same or corresponding elements may generally be indicated by same reference numerals. These depicted embodiments are to be understood as illustrative of the invention and not as limiting in any way. It should also be understood that the figures are not necessarily to scale and that the embodiments are sometimes illustrated by graphic symbols, phantom conduits, diagrammatic representations and fragmentary views. In certain instances, details which are not necessary for an understanding of the present invention or which render other details difficult to perceive may have been omitted. 
         [0027]    Turning now to the drawing, and in particular to  FIG. 1 , there is shown a view of the interior of a motor vehicle cooler housing  100 ,  115  in which a heat exchanger  7  is arranged. The cooler  115  shown in  FIG. 1  is designed as a micro-channel cooler  115  and has a plurality of conduits  111  combined in a bundle  109 . A housing  101  includes a circumferential side wall  102  and a back  103  and an (unillustrated) cover  104 . A flange  105  for connecting a supply conduit for supplying a medium is arranged on the top of the housing  101 . A flange  106  for connecting a discharge conduit for discharging a medium is provided on the bottom of the housing  101  on the side of the supply flange  105 . Connection devices  117  for attaching the housing  101  to the vehicle are provided on the side wall  102  of the housing  101  opposite the flanges  105 ,  106 . Respective reservoirs  108  for receiving the medium, which communicate with each other through the conduit bundles  109 ,  111 , are arranged on the top and the bottom of the housing  101 . 
         [0028]    In  FIG. 1 , three support plates  110  aligned substantially parallel with the reservoirs  108  extend inside the housing  101 . The support plates  110  are stacked vertically and affixed to the side walls  102  inside the housing  101 . The two reservoirs  108  are interconnected by a bundle  109  of flow-through fluid conduits  111  for guiding the flow. 
         [0029]      FIG. 2  shows an enlarged detail A of the heat exchanger  7  of the housing interior  101  of the cooler  115 , especially a micro-channel cooler  115 . The conduits  111  of the bundle  109  extend approximately perpendicular to the support plates  110  and the side walls  102  of the housing  101 . The conduits  111  are arranged in spaced-apart parallel rows in the interior of the cooler housing  101 ,  115 . The reservoirs  108  have retracted walls  114  in the region of the cover  104  and a bottom  116  of the housing  101 , which each border two rows of conduits  111 ;  113 . The flow-through fluid conduits  111  of the bundle  109  connect the reservoirs  108  and are bordered by the support plates  110  for stabilization. 
         [0030]      FIG. 3  shows a side view of the micro-channel cooler  115  with the housing  101  and the side walls  102  of the heat exchanger  107 . Reservoirs  108  are shown in the region of the cover  104  and the bottom  116 . The support plates  110  extend between the side walls  102  of the housing  101  and are pierced by the conduits  111  of the radiator  115 . In  FIG. 3 , the conduits  111  of the bundle  109  connecting the two reservoirs  108  are arranged in parallel rows. A respective supply and discharge flange  105 ;  106  are each depicted in the region of a housing side wall  101 ,  102 . 
         [0031]      FIG. 4  shows the cooler illustrated in  FIG. 3  in a lateral section (B-B). The supply flange  105  shown in a sectional view on the top side in the region of the reservoir  108 . Opposite the supply flange  105 , on the bottom side of the side wall  102 , the discharge flange  106  can be seen in the region of the lower reservoir  108 . The conduits  111  extend approximately at right angles to the support plates  110  and connect the two reservoirs  108  for guiding the flow. 
         [0032]      FIG. 5  shows in a detail from  FIG. 4  the mutually parallel conduits  111  of the bundle  109 , each having two rows of conduits  111 ,  113  bordered by the walls  114 . 
         [0033]    While the invention has been illustrated and described in connection with currently preferred embodiments shown and described in detail, it is not intended to be limited to the details shown since various modifications and structural changes may be made without departing in any way from the spirit and scope of the present invention. The embodiments were chosen and described in order to explain the principles of the invention and practical application to thereby enable a person skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. 
         [0034]    What is claimed as new and desired to be protected by Letters Patent is set forth in the appended claims and includes equivalents of the elements recited therein: