Patent Publication Number: US-6904965-B2

Title: Radiator with side flat tubes

Description:
CROSS REFERENCE TO RELATED APPLICATION(S) 
   Not applicable. 
   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
   Not applicable. 
   REFERENCE TO A MICROFICHE APPENDIX 
   Not applicable. 
   TECHNICAL FIELD 
   This invention relates to heat exchangers, and more specifically to radiators having a core formed of flat tubes and cooling fins. 
   BACKGROUND OF THE INVENTION AND TECHNICAL PROBLEMS POSED BY THE PRIOR ART 
   Heat exchangers such as radiators having one or more rows of flat tubes with cooling fins forming a core between two collecting tanks or headers are known, for example, from EP 693 617 B1 or DE 43 28 448 C2. Radiators are so-called cross-flow radiators, and are often used in passenger cars. Such radiators generally have soldered tubes and fins in the core, with the core commonly having side plates on opposite sides between the headers (i.e., with the side plates extending parallel to the longitudinal axis of the flat tubes). In aluminum cores, the side plates are generally also made from an aluminum sheet, which sheet may be variously deformed depending upon the design, and are generally soldered to the cooling fins on the outer sides of the core (i.e., the fins on the outer side of the end flat tubes). Such side plates not only protect the fins on the outer side, but reinforce the radiator by adding strength, and assist in mounting the radiator as desired (e.g., in a vehicle). Of course, the side plates also have an effect on the manufacturing cost of the radiator, and on the weight of the radiator. 
   Radiators are also known in which at least one lower or upper separated tube of a core functions as a vent tube or intake tube. However, such separated tubes are not fully available at least for operational heat exchange. DE 43 28 448 has proposed a core structure having a connection line lying on the bottom which includes part of the flat tubes of the core, where filling of the circuit is produced via this connection line. However, a check valve is required in that proposed core structure in order to separate the collecting tank on the pressure side from the collecting tank on the intake side to achieve uniform flow through all the flat tubes during operation. 
   In heavy vehicles and utility vehicles, a separately positioned hose line or the like is generally used to fill the cooling loop, with the hose line connected to the equalization vessel incorporated in the cooling loop. 
   The present invention is directed toward improving upon the above types of radiators. 
   SUMMARY OF THE INVENTION 
   In one aspect of the present invention, a vehicle radiator is provided including inlet and outlet headers, a soldered core having a plurality of coolant flat tubes joining the inlet header and the outlet header with cooling fins on opposite sides of the coolant flat tubes, and a multifunction flat tube on at least one side of the core. The multifunction flat tube has a greater section modulus than the coolant flat tubes, and is soldered to adjacent cooling fins and the inlet and outlet headers whereby the multifunction flat tube carries coolant from the inlet header to the outlet header. 
   In one form of this aspect of the invention, a second multifunction flat tube is provided on the opposite side of the core and soldered to adjacent cooling fins and the inlet and outlet headers, the second multifunction flat tube also having a greater section modulus than the coolant flat tubes. 
   In another form of this aspect of the invention, the radiator is a downdraft radiator with the inlet header on top and the outlet header on the bottom, and the inlet and outlet headers include openings receiving ends of the coolant and multifunction flat tubes. The opening receiving an end of the multifunction flat tube is larger than each of the plurality of openings receiving the coolant flat tubes. 
   In still another form of this aspect of the invention, the multifunction flat tube has substantially the same length “h” and depth “t” as the core. 
   In yet another form of this aspect of the invention, the multifunction flat tube is formed by one of soldering and welding. 
   In a further form of this aspect of the invention, the multifunction flat tube includes walls extending the depth of the core, and the tube walls are deformed along their length between the inlet and outlet headers to define separate coolant passages. 
   In still another form of this aspect of the invention, the multifunction flat tube includes flat walls extending the depth of the core, and an insert is provided between the flat walls of the multifunction flat tube whereby the insert defines coolant passages through the multifunction flat tube between the inlet and outlet headers. 
   In yet another form of this aspect of the invention, the multifunction flat tube includes flat walls extending the depth of the core with inward directed protrusions, the protrusions being connected to each other. 
   In a further form of this aspect of the invention, the inner flow resistance of the multifunction flat tube is substantially smaller than the inner flow resistance of the coolant flat tubes. 
   In still another form of this aspect of the invention, the multifunction flat tube has a wall thickness substantially greater than the wall thickness of the coolant flat tubes and a tube height substantially greater than the height of the coolant flat tubes. In one advantageous form, the multifunction flat tube wall thickness is at least two times the wall thickness of the coolant flat tubes, with the multifunction flat tube wall thickness being at least about 1.0 mm in a further form. In another advantageous form, the height of the multifunction flat tube is at least two times the height of the coolant flat tubes, with the multifunction flat tube being at least about 10 mm in a further form. 
   In yet another form of this aspect of the invention, the flat tubes extend generally vertically with the inlet header soldered to the upper ends of the flat tubes, and the radiator further includes a partition in the inlet header defining first and second chambers, the first chamber being above the multifunction flat tube and the second chamber being above the coolant flat tubes, and also includes a filling line between a coolant fill supply and the first chamber for adding coolant to the radiator. In a further form, the filling line slopes down from the coolant fill supply to the first chamber. 
   In another aspect of the present invention, a vehicle radiator is provided including inlet and outlet headers, a soldered core having a plurality of coolant flat tubes joining the inlet header and the outlet header with cooling fins on opposite sides of the coolant flat tubes, and a multifunction flat tube on at least one side of the core. The multifunction flat tube is soldered to adjacent cooling fins and the inlet and outlet headers whereby the multifunction flat tube carries coolant from the inlet header to the outlet header, and has an inner flow resistance which is substantially smaller than the inner flow resistance of the coolant flat tubes whereby more coolant flows through the multifunction flat tube than flows through an individual coolant flat tube per unit time to influence temperature distribution over the entire radiator. 
   In one form of this aspect of the invention, a second multifunction flat tube is provided on the opposite side of the core and soldered to adjacent cooling fins and the inlet and outlet headers. The second multifunction flat tube also has an inner flow resistance which is substantially smaller than the inner flow resistance of the coolant flat tubes whereby more coolant flows through the second multifunction flat tube than flows through an individual coolant flat tube per unit time to influence temperature distribution over the entire radiator. 
   In another form of this aspect of the invention, the radiator is a downdraft radiator with the inlet header on top and the outlet header on the bottom, and the inlet and outlet headers include openings receiving ends of the coolant and multifunction flat tubes. The opening receiving an end of the multifunction flat tube is larger than each of the plurality of openings receiving the coolant flat tubes. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is described in practical examples below. Reference is made to the accompanying drawing for this purpose. 
     In the drawings: 
       FIG. 1  is a face view of a first embodiment of a radiator incorporating the present invention, with the headers shown in cross-section; 
       FIG. 2  is a view similar to  FIG. 1 , showing a second embodiment according to the present invention in which the filling function is not provided; 
       FIG. 3  is a partial longitudinal section through a radiator in accordance with the  FIG. 1  embodiment, where only about half of the inlet header is shown; 
       FIG. 4  is a partial longitudinal section through a radiator in accordance with the  FIG. 2  embodiment; 
       FIGS. 5   a-c  illustrate an end of one multifunction flat tube which may be used in accordance with the present invention; 
       FIGS. 6   a-c  illustrate an end of another multifunction flat tube which may be used in accordance with the present invention; 
       FIGS. 7   a-b  illustrate an end of still another multifunction flat tube which may be used in accordance with the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   A radiator  10  incorporating elements of the present invention is shown in FIG.  1 . The illustrated radiator  10  may be used, for example, in heavy vehicles in order to cool the cooling liquid of the internal combustion engine, and is a so-called downdraft radiator in which the inlet collecting tank or header  12  is arranged on the top and the outlet collecting tank or header  14  on the bottom. The inlet header  12  has an inlet connector  20  and the outlet header  14  has a corresponding outlet connector  22  with which the radiator  10  together with an equalization vessel (not shown) and other corresponding elements may be incorporated in a cooling loop (not shown). 
   The radiator  10  includes a soldered core  26 , of a type which is generally known, including alternating arranged coolant flat tubes  30  and cooling ribs or fins  32 . In the illustrated radiator  10 , the flat tubes  30  may have a height (i.e., minor dimension between the fins  32  on opposite sides of the tubes  30 ) of only about 1.8 mm, and without inserts therein. Also, in the illustrated radiator  10 , the fins  32  are serpentine. 
   In accordance with the present invention, multifunction flat tubes  40  are provided on opposite sides of the core  26 , soldered to the fins  32  on the outer side of the last coolant flat tubes  30  to thereby provide for good heat transfer. 
   In accordance with the present invention, the multifunction flat tubes  40  also provide a rigid side to the core  26  to prevent outward expansion or bulging of the core  26 , whereby the side plates such as used with prior cores of this type may be omitted. The multifunction flat tubes  40  have a significantly higher section modulus Wx, Wy (see  FIG. 7   b ) than do the prior art side plates. As a result, the multifunction flat tubes  40  can be produced with walls formed of a significantly thinner sheet than such prior art side plates, without increasing the weight of the core  26  or reducing the stability of the core  26 , while still providing the required strength desired for suitable core stability. 
   The section modulus Wx, Wy of the multifunction flat tubes  40  is also significantly greater than the section modulus of individual coolant flat tubes  30 . Specifically, the multifunction flat tubes  40  are made from a sheet having a greater thickness “b” (see  FIG. 7   b ), and have a significantly greater height “d”, than the coolant flat tubes  30 . For example, the multifunction flat tube  40  may have a height “d” on the order of 10 mm, but in any case should have a height which is at least twice the height of the coolant flat tubes  30  (e.g., where the tubes  30  have a height of about 1.8 mm as previously indicated, the multifunction flat tubes  40  would have a height “d” of at least about 3.6 mm). The walls of the multifunction flat tubes  40  may similarly be advantageously formed with sheets having a thickness “b” which is significantly greater than the thickness of the walls of the coolant flat tubes  30  (e.g., a sheet thickness of about 1.0 mm for the multifunction flat tubes  40  versus a sheet thickness of about 0.1-0.4 mm for the coolant flat tubes  30 ). 
   The multifunction flat tubes  40  have generally the same depth “t” (see  FIG. 7   d ) and same length “h” (see axis “h” in  FIG. 1 ) as the coolant flat tubes  30 , so as to generally extend over the full sides of the core  26 . Where a core is formed having multiple tube rows, however, the depth “t” of the multifunction flat tubes would be correspondingly greater than the depth of the tubes given the greater core depth (i.e., the depth “t” would be the depth of the coolant flat tubes times the number of tubes plus the spacing between the tube rows). 
   Like the coolant flat tubes  30 , the multifunction flat tubes  40  are suitably connected to the inlet and outlet headers  12 ,  14  on their ends  42  so as to provide coolant flow paths between the headers  12 ,  14 . 
   Referring now specifically to the embodiment shown in  FIGS. 1 and 3 , a filling opening  50  is provided on the inlet header  12 , with the fill opening  50  connected to a supply of coolant and open to a filling line  54  suitably secured to the inside of a wall  56  of the inlet header  12 . The filling line  54  is sloped downward from the fill opening  50  toward the sides of the inlet header  12 , which is divided into a middle or central chamber  60  and two side chambers  62 ,  64  by generally vertical partitions  68  positioned between the multifunction flat tubes  40  and the adjacent, outermost coolant flat tubes  30 . Thus, the filling line  54  leads from the fill opening  50  to the two side chambers  62 ,  64 . 
   As described in greater detail in  FIGS. 5   a - 7   b  below, the multifunction flat tube  40  may advantageously be configured in a number of different ways whereby its inner flow resistance ensures circulation therethrough in a suitable period of time. Specifically, the multifunction flat tubes  40  may be advantageously configured to ensure that a filling function is provided whereby the requisite cooling liquid to be filled can be introduced into the cooling loop in an acceptable time. Filling may occur through a suitable equalization vessel connected to the fill opening  50 . In a compact design, the equalization vessel may be situated directly on the inlet header  12 . Air escaping upward during filling of the cooling loop passes through a radiator vent  70  integrated in the cover  72  of the fill opening  50  (see FIG.  3 ). 
   Moreover, since the multifunction flat tubes  40  are continuously traversed by coolant during operation and therefore participates in heat exchange, the particular multifunction flat tube design chosen may advantageously seek an optimum between providing a short fill time and providing the highest possible heat exchange rate of the multifunction flat tubes  40 . During cooling operation, a portion of the coolant continuously flows from the equalization vessel through the filling line  54  into the side chambers  62 ,  64  and through the multifunction flat tubes  40  so that these can make a contribution to cooling of the coolant, in which the heat is taken off via the cooling fins  32  traversed by cooling air. Specifically, with cores of this type according to the prior art, the temperature distribution ordinarily has a parabolic trend over the width of the radiator, with the maximum temperature line roughly in the center of the core and the outer lying flat tubes generally poorly traversed and hardly participating at all in heat exchange. In accordance with the present invention, the multifunction flat tubes  40  contribute to deliberate equalization of the temperature over the entire radiator  10 . 
     FIG. 2  illustrates a second embodiment of an advantageous radiator  10 ′ in accordance with the present invention. In the illustration, components essentially the same as components as in  FIG. 1  are given the same reference numerals, and similar but modified components are given the same reference number with a prime added. 
   With the  FIG. 2  embodiment, the inlet header  12 ′ has a single chamber open to all of the flat tubes  30 ,  40 , whereby a separate filling function is not provided. Nonetheless, advantageous equalization of temperature distribution over the entire radiator  10 ′ in accordance with the present invention is achieved, as is the provision of a stable core  26 . Further, while the side plates of the prior art may advantageously be omitted in accordance with the present invention, cooling equalization may nonetheless be provided even with such side plates. Specifically, given the greater cross-sectional size of, and lower flow resistance through, the multifunction flat tubes  40  as compared to the coolant flat tubes  30 , a larger stream flows through the multifunction flat tube  40  than through each individual coolant flat tube  30  as indicated by the arrows  74  marked in the inlet header  12 ′ in FIG.  2 . 
   It should also be understood that the inner flow resistance in both multifunction flat tubes  40  do not necessarily need to be equally large, and it would be within the scope of the present invention, and even advantageous in certain designs, to provide unequal flow resistance in the multifunction flat tubes  40  so that the flow amounts in the two multifunction flat tubes  40  may be different. Moreover, provision of only one multifunction flat tube on one side of the core may also advantageously benefit from the present invention in certain designs. 
   It should thus be appreciated that multifunction flat tubes  40  such as described above may be used not only to improve performance, but may also be used to reduce temperature differences across the core which can lead to stress cracking. 
     FIG. 4  illustrates one suitable connection between the flat tubes  30 ,  40  and the headers  12 ,  14 . Specifically, openings  78  are present in the tube ends  80  which are received in collars  82  in the header plate  84  (whereby the plate  84  defines the tube ends of the core). The collars  82  are tapered toward the core. This connection provides a high quality, leak proof solder connection between the flat tubes  30 ,  40  and heater plate  84 . It should be understood, however, that still other connections between the flat tubes  30 ,  40  and the headers  12 ,  14  could also be advantageously used in connection with the present invention. 
   The header plate  84  may include a continuous groove  86  with a seal  88  arranged in the groove  86 , whereby the headers  12 ,  14  may be formed by firmly and tightly mechanically joining the edge of the header plate  84  to the edge a plastic housing  90  (see FIG.  4 ). As with the  FIG. 2  embodiment, no filling function is provided in the inlet header  12 ′ illustrated in  FIG. 4   
     FIGS. 5   a-c  disclose one embodiment of a multifunction flat tube  40   a  which may be advantageously used with the present invention. The multifunction flat tube  40   a  advantageously has a bead  92  or similar deformation on its ends  42 . This bead  92  serves as a stop of the multifunction flat tube  40   a  during assembly of the core (i.e., during assembly of the flat tubes  30 ,  40  the fins  32  with the header plates  84 , which are assembled before performing the soldering process). A suitable insert  94  may also be provided in the multifunction flat tube  40   a , with the insert  94  suitably secured therein (as by soldering to the long side walls of the tube  40   a ) to further enhance the stability of the multifunction flat tubes  40   a  (and thereby the stability of the core  26 ) as well as providing coolant flow passages providing enhanced heat transfer with the coolant flowing through such tubes  40   a.    
     FIGS. 6   a-c  illustrate another multifunction flat tube  40   b  which may be advantageously used with the present invention. The tube  40   b  may be formed of a bent sheet of material suitably sealed, as by soldering or welding, along a longitudinal joint. As illustrated, the tube  40   b  also includes an insert  94  such as shown in the embodiment of  FIGS. 5   a-c.    
     FIGS. 7   a-b  illustrate yet another multifunction flat tube  40   c  which may be advantageously used with the present invention. In this embodiment, the long side walls  96  of the tube  40   c  include inwardly directed protrusions  98  which are suitably connected to the opposite side wall  96  (e.g., by soldering to a similar protrusion  98 ). 
   Still other multifunction flat tube designs using these and/or other features could be advantageously used within the scope of the invention. For example, longitudinally extending inwardly directed protrusions could be soldered together (similarly to the longitudinally spaced protrusions  98  of the  FIGS. 7   a-b  embodiment) so as to define separate parallel flow paths through such a tube. 
   It should thus be appreciated that radiators incorporating the present invention may benefit from one or more of the various benefits provided thereby. A filling function can be provided to assist in achieving proper operation of the radiator. Also, a single core design may be used for radiators with or without a filling function. Further, a stable core may be provided without significantly impacting the weight or size of the radiator, whereby the side plates required in the prior art may be omitted. Still further, the ability to assemble the multifunction flat tubes  40  together with the coolant flat tubes  30 , without requiring assembly of such side plates, provides manufacturing advantages. Moreover, performance of the radiator may be improved by achieving a more uniform temperature distribution over the entire radiator core dues to the side regions of the radiator being heated more quickly as a result of the multifunction flat tubes. 
   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.