Patent Publication Number: US-4651821-A

Title: Heat exchanger with tubes and fins and tube-plates

Description:
This application is a continuation of application Ser. No. 312,844, filed 10/19/81, now abandoned. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates to the manufacture of heat exchangers and to a novel and particular heat exchanger. 
     The manufacture of heat exchangers which are particularly usable for cooling engines conventionally uses tubes of circular section which are engaged into bundles of fins into which they are then inflated. In some known embodiments, the tube-plates ae then set in place on the ends of the tubes which protrude beyond the fins, so that subsequent inflation provides the mutual fixation of the tubes and tube-plates. 
     In order to insure a good tight fit, a flexible gasket is most often interposed between the outer wall of the tubes and collars formed on the tube-plates. Headers are thereafter fixed by means of tongs or clips or by crimping on the tube-plates. 
     The hereabovementioned embodiment gives relative satisfaction but is costly since it requires two inflating operations of the tubes, and successive manipulations since, in addition to the successive inflations of the tubes, the crimping or other fastening of the headers on the tube-plates has to be carried out subsequently. 
     In another known embodiment, the tubes are inflated simultaneously in tube-plates and a bundle of fins, and then tie rods are interposed between the tube-plates so that the distance between said tube-plates remains constant even after a prolonged usage, viz. after a large number of expansion and contraction cycles of tubes. 
     Another known embodiment involves inflating the tubes in a bundle of fins and then in forcibly inserting tube-plates provided with resilient sockets onto the protruding ends of the tubes. In this last embodiment, the tube-plate can comprise a separate insert header or may be formed by the wall of a hollow body forming both a header and a tube plate. 
     This last embodiment is the most simple but it can happen sometimes that the tube-plates are displaced relative to the tubes of the core since they are held simply by friction of the resilient sockets against the wall of the tube ends. 
     SUMMARY OF THE INVENTION 
     The present invention has for its object to remedy this disadvantage without making the manufacture more complex. 
     According to the invention, the heat exchanger is of the type comprising a tubular core with tubes engaged into perforations of fins, the tubes being designed for being tightly connected to tube-plates by means of deformable gaskets and, is characterized in that the tube-plates comprise resilient interlocking means cooperating with mating portions of the core. 
     Various further features of the invention will become more apparent from the following detailed description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Embodiments of the invention are shown by way of non limiting examples in the accompanying drawings, wherein: 
     FIG. 1 is diagrammatic elevation view, partly in section, of a heat exchanger made according to the invention; 
     FIG. 2 is a partial cross-section of a heat exchanger, similar to that of FIG. 1, illustrating a particular feature; 
     FIGS. 3-5 are partial cross-sectional elevation views similar to FIG. 2 illustrating various alternative embodiments. 
    
    
     DETAILED DESCRIPTIONS OF THE INVENTION 
     Referring now to the drawings, the heat exchanger of FIG. 1 comprises a core made of tubes 1 of a circular cross-section engaged into collars 2a of fins 2. Once the tubes are engaged into the fins, the tubes are inflated so that they exert a permanent pressure inside the collars, thereby providing on the one hand the mechanical connection between the tubes and the fins and enhancing on the other hand the heat conductivity between these members. 
     In the embodiment shown in FIG. 1, there is placed on either side of the bundle of fins 2, a form of fin 3 herein-after called &#34;false collector&#34; formed with collars 3a in which the tubes 1 are also inflated, so that the false collector 3 is fixed to the tubes in the same way as the rest of the fins. 
     The tube-plates, designated at 4 and 4a, are made of a moulded material, for example a synthetic material, and they are formed with tube passages 5 into which are placed resilient sockets 6 defining a holding flange 7 for bearing against the inner face of the tube-plate 4. It is advantageous, as shown in the drawings, that the sockets 6 are formed from a continuous plate 8 extending on the side of the tube-plate turned towards the core. The tube-plate is provided in various positions and in particular at its ends with protruding studs 9 which are resiliently deformable and comprise burrs or a holding ring 10 formed in register with openings 3b of the false collectors 3. In order to be resiliently deformable, the studs 9 are for example slit in their longitudinal direction as shown by notch 11. 
     Each tube-plate 4, 4a is rigidly and tightly fixed to a header 12, 12a. In the example shown, the headers 12, 12a are connected to the tube-plates 4, 4a via a gasket and one or several tongs or clips 14. Other modes of fixation can be used amongst those known in the art. In particular when the tube-plates and the headers are made of a synthetic material, it is possible to connect them by ultrasonic or vibration welding, or by gluing. 
     FIG. 2 shows another embodiment in which each tube-plate and header sub-assembly is substituted by a hollow body 15 forming a tube-plate 15a and a header 15b. This hollow body is open at one end for its removal from the mould and said open end contains a cover 16 which can define a fitting 17 for connecting the header to a feeding pipe or, on the contrary, to a discharge pipe of the circulation fluid. 
     In the following disclosure, when the description refers to a tube-plate and header, either of the embodiments described with reference to FIG. 1 or to FIG. 2 are to be considered indifferently. 
     In order to make the heat exchanger, as described hereabove, one proceeds as follows: 
     The tubes 1 are engaged into a bundle of fins 2 and into the false collectors 3 placed on either side of the fin bundle. The tubes 1 are then inflated and thereby rigidly connected to the fins and to the false collectors. On the other hand, the sub-assemblies formed by the tube-plates 4, 4a and their headers 12, 12a or by the hollow bodies 15 are prepared. The tube-plates 4, 4a or the parts 15a which are used instead are then provided with the sockets 6 with collars 7, and these sub-assemblies are inserted onto the protruding ends of the tubes 1 until the studs 9 are interlocked into the openings 3b provided to this effect in the tube-plates. 
     When referring to the embodiment of FIG. 1, one would not depart from the scope of the invention by first putting in position the tube-plates 4, 4a so that the studs 9 are interlocked into the openings 3b, and then assembling on said tube-plates 4, 4a the headers 12, 12a. 
     FIG. 3 illustrates an alternative embodiment according to which the false collectors 3 are formed on two at least of their sides with upright edges 18 comprising openings 19 mating with protruding edges 20 formed by each tube-plate 4, 4a, said protruding edges 20 being oblique in order to define ramps 21 the most narrow portion of which is standing back relative to the inner wall of the upright edges 18. The other portions of the heat exchanger are similar to those described hereabove. 
     When the tube-plate-header subassemblies are prepared with the sockets 6 in position, these subassemblies are forcibly driven onto the ends of the tubes 1 until the protruding edges 20 are interlocked into the openings 19. 
     FIG. 4 shows another alternative embodiment according to which a number of tubes 1a of the core are shorter than the tubes 1 and are placed in the fins 2 opposite the studs 9 protruding from the tube-plates 4. The tubes 1a are formed in their walls with latching openings 22 into which are interlocked the burrs 10 of the deformable studs 9. This embodiment permits the false collectors 3 described hereabove to be omitted, the tubes 1a forming moreover tie rods between the two heat exchanger tube-plates. The tubes 1a have perferably in cross-section the same diameter as the tubes 1, but they can have, without departing from the scope of the invention, a different diameter and even, possibly, a cross-section which is not a circular shape. 
     FIG. 5 illustrates still another alternative embodiment according which the tube-plates 4, 4a comprise, on their side turned towards the fins 2, studs 23 formed on a portion at least of their lateral surface with teeth 24. 
     Openings 25 having a shape mating with that of the studs 23 are cut out in the fins 2, these openings not comprising collars. The shape in cross-section of the studs 23 as well as that of the openings 25 can be as desired, for example circular, but they can also be polygonal if it is desired that the tube-plate-header subassemblies can be put in place only in a single position relative to the core, viz. that the openings and studs serve then as means to prevent positioning errors, such a feature being provided either by the shape or by the disposition of the studs. It is also advantageous that the shape of the teeth is chosen such that the introduction is carried-out without great effort, viz. that the anterior face of the teeth is inclined, while the extraction is made difficult, and even impossible, by virtue of the fact that the rear face of the teeth is plane or reversed relative to the inclination of the anterior face. 
     The arrangement described hereabove with reference to FIG. 5 also facilitates the use of a core which does not include false collectors and in which the studs with their teeth 24 can be used as bracing elements for the fins if said studs are designed for being engaged over a substantial height, even up to half of the height of the core. 
     The invention is not limited to the embodiments shown and described in detail and various modifications can be carried out without departing from the scope of the invention. For example, the fixation means of the heat exchanger to a frame or chassis, for example the body of a vehicle, can be indifferently provided on the headers 12, 12a, the tube-plates 4, 4a or on side flanges attached either to the fins, the tube-plates or the headers, or even to the false collectors when such false collectors are provided.