Abstract:
The invention relates to a manifold, of the type comprising a substantially flat plate ( 20 ) with holes ( 22 ) to accept tubes of a heat exchanger, and turned-up lateral edges ( 24 ) extending at an angle to said plate ( 20 ) and connected thereto by at least one curved portion in which ribs ( 52 ) are formed, the ribs each having a convexity extending substantially in the direction of extension of the lateral edges ( 24 ). The plate ( 20 ) comprises at least one additional rib ( 50 ) between at least some of said holes ( 22 ), which ribs each have a convexity extending substantially in the opposite direction to the direction in which the lateral edges ( 24 ) extend.

Description:
RELATED APPLICATIONS 
     This application claims priority to and all the advantages of International Patent Application No. PCT/EP2006/067960, filed on Oct. 31, 2006, which claims priority to French Application No. FR 0511181, filed on Nov. 2, 2005. 
     BACKGROUND OF THE INVENTION 
     The invention relates to the field of heat exchangers and deals more specifically with a manifold for a header tank, of the type comprising a substantially flat plate with openings to accept tubes of a heat exchanger, and turned-up lateral edges extending at an angle to said plate and connected thereto by at least one curved portion in which ribs are formed, the ribs each having a convexity extending substantially in the direction of extension of the lateral edges. 
     Manifolds such as this are used in particular in header tanks obtained by two-part manifold assembly, namely a manifold and a cover, the manifold usually being made of aluminum or aluminum-based alloy. 
     Header tanks such as this are used in heat exchangers and, in particular, in motor vehicle engine cooling radiators or radiators used as intercoolers. In such radiators, the coolant or the supercharging air flowing through the header tank and through the tubes is at a high pressure and at a temperature that may exceed 100° C. One of the chief difficulties when designing such header tanks is that of making the manifold suitably able to withstand pressure without using too great a thickness of material from which to make it. 
     Certain header tanks the design of which is aimed at solving this problem are already known, for example the one disclosed in US 2003 217838. In that document, the manifold has a substantially U-shaped cross section and its thickness is doubled by a fold of material where the branches of the U meet the bottom of this U. This type of design increases the amount of raw material used and occupies a great deal of space, and the fact that the manifold has to be brazed to itself at the folds prevents, among other things, the use of a corrosion-resistant coating within it. 
     FR 2 720 490 discloses a manifold plate that has openings in a substantially flat region that meets at least one curved region of cylindrical overall shape deviating from the plane of the flat region, in which the cylindrical shape is interrupted by a multitude of recessed zones. While it offers good yield strength, this type of manifold plate is nonetheless particularly ill-suited to the insertion of tubes. 
     The invention aims to improve the situation. 
     SUMMARY OF THE INVENTION 
     To that end, the invention proposes a manifold, of the type comprising a substantially flat plate with holes to accept tubes of a heat exchanger, and turned-up lateral edges extending at an angle to said plate and connected thereto by at least one curved portion in which ribs are formed, the ribs each having a convexity extending substantially in the direction of extension of the lateral edges, the plate further comprising additional ribs between at least some of said holes. Advantageously, the ribs of the plate each have a convexity extending substantially in the opposite direction to the direction in which the lateral edges extend. 
     In one embodiment, the ribs of the plate are positioned between each of the holes, and each hole is thus surrounded by two ribs the convexities of which form a guide for inserting a tube. 
     A manifold such as this is particularly attractive in that it offers good yield strength and ability to withstand pressure by virtue of the ribs produced, while at the same time offering the possibility of guiding the tubes in order to insert them. 
     In another embodiment, the lateral edges also have ribs, it being possible for the ribs of each lateral edge each to have a convexity extending in the directions of the opposite lateral edge. At least some of the ribs of the lateral edges may be positioned in the continuation of the ribs of the curved portion or, by contrast, may be positioned on the manifold in such a way that they alternate with the ribs of the curved portion. Advantageously, the ribs of the lateral edges extend over part of the lateral edges not including the end of these edges. 
     A manifold such as this is further strengthened by the presence of the ribs on the lateral edges. Positioning the ribs of the lateral edges in the continuation of or, on the other hand, alternating with, the ribs of the curved portion allows better control over the way in which the manifold deforms. Furthermore, positioning the convexity of the ribs toward the opposite lateral edge, that is to say toward the inside of the header tank when this tank is mounted, allows for a space saving. Finally, the limited extent of the ribs of the lateral edges means that a cover can be positioned inside the edges of the manifold, to which it can then be attached using known methods. 
     In one embodiment, the manifold has a substantially U-shaped cross section the branches of which U form the lateral edges. The manifold can also be made of aluminum or aluminum alloy. 
     The invention also relates to a header tank which comprises a manifold that has the features quoted hereinabove, and a cover to close the manifold. 
     In one embodiment, the manifold and the cover both have a substantially U-shaped cross section. The branches of this U form the respective lateral edges for the two pieces of manifold assembly, the cover being able to be brazed to at least a part of the lateral edges of the manifold, near the end of these edges. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other features and advantages of the invention will become better apparent from reading the following description given by way of non-limiting illustration and taken from examples based on the drawings in which: 
         FIG. 1  is a partial side view of a heat exchanger comprising a header tank according to the invention; 
         FIG. 2  is a view in section, on a larger scale, of the header tank on II-II of  FIG. 1 ; 
         FIG. 3  is a view in part section on III-III of  FIG. 2 , taken at one end of the header tank; 
         FIG. 4  is a partial perspective view showing the ribs of the manifold; and 
         FIG. 5  is a partial perspective view of an alternative form of  FIG. 4 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Reference is made first of all to  FIG. 1  which shows a heat exchanger  10  comprising a header tank  12  according to the invention, into which the ends of the tubes  14  of a heat exchanger bundle open. The tubes  14  are parallel flat tubes between which are positioned corrugated inserts  16  that form heat exchange fins. The heat exchanger  10  comprises an opposite header tank (not depicted) analogous to the header tank  12 . 
     The exchanger  10  finds a particular application in motor vehicles and is designed to be produced by brazing in a single operation while at the same time offering good ability to withstand pressure and a high yield strength. 
     As can be seen in the sectioned view of  FIG. 2 , the header tank  12  is made up of two metal components nested one inside the other intended to be assembled by brazing. The header tank  12  comprises a manifold  18  produced in the form of a metal element (for example made of aluminum or an aluminum alloy) with a U-shaped profile having a bottom wall or plate  20  equipped with holes  22  for the insertion of tubes  14 . The manifold also has two lateral walls or lateral edges  24  connected to the plate  20 . The lateral walls  24  of the manifold  18  that form the two branches of the U are of identical heights, although it is possible for the height to vary relative to the bottom wall  20 . The plate  20  is generally flat and the same is true of the lateral edges  24 . These meet the plate  20  at an angle of about 90°. This angle could be different. The plate  20  is connected to the lateral edges  24  via curved portions  26 . 
     As can be seen in  FIG. 1  and also in  FIG. 3 , the lateral edges  24  have a variable height near the end of the manifold  18 . In particular, the lateral edges  24  of the manifold have two curved portions  28  each of which extends as far as the plate  20 . 
     The header tank  12  comprises another piece, namely a cover  30  made in the form of a metal element (for example of aluminum or an aluminum alloy) with a U-shaped profile having a bottom wall  32  extending in a plane parallel to the plane in which the plate  20  extends, and two lateral walls  34  connected to the bottom wall  32 . The lateral edges  34  of the cover are generally flat and make an angle of about 90° with the bottom wall  32 . As depicted in  FIG. 2 , the lateral walls  34  of the cover  30  that form the two branches of the U may be of identical heights. 
     The cover  30  is nested inside the manifold  18  in such a way that their respective U-shaped profiles face in the same direction, that is to say away from the tubes  14  of the heat exchanger bundle. 
     The result of this is that the lateral walls  34  of the cover  30  come into contact, via their outside, with part of the lateral edges  24  of the manifold  18 , on the inside of the latter ( FIG. 2 ). 
     The cover  30  further comprises two end regions  36  ( FIG. 3 ) each of which is curved toward the plate  20  of the manifold  18 . In each of these end portions, the bottom wall  32  of the cover has a curved portion  38  ending in a rim  40  capable of pressing against the plate  20  of the manifold  18 . The rim  40  is itself connected to a bent part  42  of each lateral edge of the cover to close the header tank  12 . 
     Large surface areas with good surface contact that are highly suitable for brazing can thus be brazed together. The manifold  18  is advantageously produced by bending a metal sheet such that it can be given a U-shaped profile, the holes  22  intended for the insertion of the tubes  14  preferably being produced in the metal component after bending. 
     The cover  30  for its part is advantageously produced by pressing, the end portions of the cover also being produced during this pressing operation. 
     To strengthen this header tank, ribs are made in the manifold  18 .  FIG. 4  is a perspective part view of the header tank  12  providing a better illustration of how the ribs are distributed. 
     Prior to bending, the manifold  18  is pressed to form three distinct types of rib in the plate  20 , the lateral edges  24  and the curved portions  26 . 
     Ribs  50  are first of all produced between each of the holes  22 . The ribs  50  extend over the entire width of the plate  20  between the curved portions  26  and the lateral edges  24 . The ribs  50  thus extend uniformly over the length of the manifold  18 . 
     The ribs  50  have a substantially V-shaped cross section and are produced toward the outside of the tank  12 . The ribs  50  thus have a convexity extending substantially in the opposite direction to the direction in which the lateral edges extend. 
     The ribs  50  thus form projections surrounding the holes  22 . Each pair of ribs  50  surrounding a given hole  22  forms a guide for the insertion of the tubes  14 , each by way of one branch of the V of which it is formed. 
     Other types of cross section for the ribs  50  are conceivable, so as to allow even better insertion of the tubes  14  while at the same time providing the manifold  18  with optimum rigidity. 
     Ribs  52  are produced in the curved portions  26 . Like the ribs  50 , the ribs  52  extend in the direction of the width of the plate  20  and are each positioned facing a rib  50  in the continuation thereof. 
     The ribs  52  are produced toward the inside of the tank  12 . The ribs  52  thus have a convexity extending substantially in the direction in which the lateral edges  24  extend. A region  54  allows each rib  50  to be connected to the rib  52  which is its continuation and which departs in substantially the opposite direction. 
     The ribs  52  allow for a substantial improvement in the ability to withstand pressure and in the yield strength. This aspect is all the more critical because, traditionally, the portions  26  have constituted significant weak points in header tanks of the type that the tank  12  represents. 
     Finally, ribs  56  are produced in the lateral edges  24 . Like the ribs  50  and  52 , the ribs  56  extend in the direction of the width of the plate  20  and are each positioned facing a rib  52 , in the continuation thereof. 
     The ribs  56  are also produced toward the inside of the tank  12 . The ribs  56  thus have a convexity extending substantially in the direction of the opposite lateral edge. The ribs  56  extend over most of the lateral edges  24 , up to a chosen distance away from the end of the edges  24  that will allow the cover  30  to be housed and brazed into the manifold  18 . 
     In the example described here, the ribs  50 ,  52  and  56  are not only in the continuation of one another but are also continuous. These ribs thus form a rib which extends over the entire width of the manifold  18 , from a position close to the end of one lateral edge to another position close to the end of the opposite lateral edge, passing via the plate. Furthermore, while all the holes  22  depicted are flanked by ribs  50 ,  52  and  56 , the invention does not exclude the situation whereby the holes  22  at the ends of the plate  20  are flanked by just one rib  50 ,  52  or  56 , or none at all. 
     In another embodiment depicted in  FIG. 5 , the ribs  50  and  52  are unchanged in their constitution and layout. By contrast, the ribs  56  are offset, and each positioned facing a hole  22 , that is to say such that they alternate with a rib  52 . 
     The invention is not restricted to heat exchangers the header tanks of which are made of aluminum or aluminum alloy. It may in particular be applied to header tanks with the plate and the cover made of plastic, ribs then being produced for example at the groove in the manifold plate and between the holes that this comprises. 
     Furthermore, a person skilled in the art will be able to conceive of all the alternative forms that arise out of studying the claims that follow.