FR2777645A1 - Heat exchanger for a vehicle made from a bundle of thermoplastic tubes and end blocks - Google Patents

Abstract

Each end block has a collector (14) in the form of a plate with orifices (16) into which the ends of the tubes are sealed, and a fluid box (18) sealed by the collector to form an internal volume. At the end of each tube an insert (34) is fitted at least partly in the tube so the outside edge of the insert acts with the matching inside edge of the tube to stiffen it near its opening. The transverse section of the tube is oblong or elongated and the insert has a contour which matches this section and has transverse barriers inside it joining the two sides and acting as stiffeners. The insert is partially introduced into the tube, with the sticking out section connecting to the orifice in the collection plate. The tube and the insert, and the insert and the collector, are sealed together by gluing or welding. The sticking out part of the insert is inclined axially inwards to fit into the orifice in the collector. The part of the insert fitted into the tube is inclined axially inwards to fit into the tube. The whole of the insert is fitted into the tube and the tube wall is jammed between the insert and the orifice. The collector and the tube are sealed together by gluing or welding. Over part of its length between the insert and the opening, the tube has a flared section which fits into a flared section in the orifice. Fabrication process for making such an exchanger comprises: (a) Making a number of thermoplastic tubes; (b) introducing at least partially into the tubes an insert; and (c) assembling into a bundle and fixing them to end blocks which have a collector containing orifices to receive each tube. The insert is partially inserted into the tube and the rest is fixed to the collection plate by gluing or welding, or the insert is fitted right into the tube and the tube is jammed between the insert and the orifice and then welded or glued.

Description

A Heat exchanger in bonded thermoplastic material for vehicle

  The invention relates to the technology of heat exchangers

for motor vehicles.

  It applies to the different types of heat exchangers that can be encountered in a vehicle, such as radiator for heating the passenger compartment, cooling the engine or the charge air, or even the circuit condenser.

air conditioning.

  These exchangers consist of a bundle of tubes carrying out the heat exchange with the external environment. The bundle tubes are connected on both sides by two end blocks defining the path of circulation of the fluid in the tubes and making it possible to introduce the fluid

  into the exchanger and extract it.

  Each of the end blocks comprises a collecting plate or "plate with holes" into which the tubes of the bundle open, secured in a sealed manner to this plate at the place of their outlet. This plate, generally designated "collector", is associated with a closure cover or

  "fluid box" so that manifold and box are defined-

  feels a common volume into which all the ends of the bundle tubes open. This volume can possibly be subdivided by transverse partitions into distinct sub-volumes making it possible to define the circulation of the fluid in groups of particular tubes, opening into the same sub-volume. It is also by the boxes

  fluid that the fluid inlet and outlet are operated on.

  A heat exchanger therefore comprises various elements, which it

need to assemble together.

  The invention relates to the particular case where these elements are, in

  all or part of the plastic elements.

  In this case, the tubes of the exchanger can be advantageously

  ment made by extrusion, thermoforming, etc. and are assembled to the collector by bonding and / or welding ("bonding" here designating an assembly with addition of glue or with an adhesive already incorporated in the plastic material and "welding" designating an assembly of two parts by application of

  heat, ultrasound, etc. to thermoplastic material).

  It is known in particular to produce, by this technique, very flat tubes, which allow good heat exchange with the surrounding air due to their large unit area, without it being in particular necessary to

  provide cooling tubes between the tubes.

  However, due to this flattened shape and the flexibility of the plastic, the assembly of the tubes to the collector is sometimes made delicate, insofar as one must in particular ensure a perfectly sealed connection between

  tubes and manifold over the entire periphery of the tubes.

  The invention provides a particular structure of this type of heat exchanger, as well as a manufacturing process,

  to guarantee an excellent seal of the assembly

  wiring between the various tubes of thermoplastic material and the manifold of the end block, and this without significantly increasing the final cost of the exchanger or providing

  excessive complication in the manufacturing process.

  The heat exchanger of the invention is of the known type comprising a bundle of parallel tubes made of preformed thermoplastic material and two end blocks joining these tubes. Each end block comprises a plate-shaped manifold provided with orifices in which the ends of the bundle tubes engage in a sealed manner, and

  a fluid box tightly closed by the collection

  tor to define an interior volume with it.

  According to the invention, this exchanger comprises at each end of the tube an insert housed at least partially in the tube so that the peripheral outer surface of the insert cooperates with a homologous peripheral internal surface of the

  tube by stiffening the latter in the vicinity of its outlet.

  Very advantageously, the cross section of the tubes is oblong or elongated, while the insert has a homologous outline of this section and is provided in its internal region with transverse stiffening partitions

  joining the opposite sides of this outline.

  In a first embodiment, the insert is partial-

  introduced into the tube, its emerging part cooperating

  with the homologous orifice of the collector.

  Advantageously, in this case, the tube and the insert, as well as the insert and the manifold, are joined together and in a sealed manner by bonding or welding; moreover, in cross section the emerging part of the insert may have a portion of external peripheral surface inclined axially inwards which cooperates with a homologous inclined surface of the collector, as well as the part of the insert introduced into the tube. can also be tilted axially inwards and cooperate with

a homologous flare of the tube.

  In a second embodiment, the insert is fully introduced into the tube, the wall of the tube then being clamped between the outer surface of the insert and a surface

  interior homologous to the manifold orifice.

  Advantageously, in this case, the collector and the tube are joined together and in a sealed manner by bonding or welding; moreover, the tube may have, in a region of its length situated between the insert and the outlet of the tube, a flared part cooperating with a homologous flare

of the manifold orifice.

  The invention also relates to a method for producing a heat exchanger of the above type, comprising the steps consisting in: a) producing a plurality of tubes of material

  preformed thermoplastic; b) introduce at least partial-

  ment in the tubes, at each of their ends, an insert stiffening these tubes in the vicinity of their outlets; and c) assembling the various tubes in bundles and joining them by end blocks each comprising a collector made of thermoplastic material in the form of a plate joining between

  they the corresponding ends of the bundle tubes.

  In the case of the aforementioned first embodiment, in step b) the insert is partially introduced into the tube, its emerging part cooperating with the homologous orifice of the manifold, and step c) of assembly is carried out by gluing or welding tubes to inserts, and inserts to

collector.

  In the case of the second embodiment mentioned above, in step b) the insert is completely introduced into the tube beyond the outlet of the latter, and step c) of assembly is carried out by flaring the part free protruding from the tube against a homologous flare of the manifold orifice,

  then bonding or welding the tubes to the collector.

  Other characteristics and advantages of the invention

  will appear on reading the detailed description below

  below of exemplary embodiments, with reference to the appended drawings.

  FIG. 1 is a general perspective view of a sample

  plastic heat absorber from which some of the elements of the tube bundle have been removed to leave

  show the manifold holes.

  Figure 2 is a perspective view of one of the tubes of the heat exchanger of Figure 1 with its inserts

  end, according to a first embodiment of the invention

  tion. Figure 3 is a detail showing, in section through a vertical plane, the assembly of the ends of the tubes to the manifold

with interposition of inserts.

  FIG. 4 is a partial view, in section and in perspective.

  ve, of a second embodiment of the invention.

  Figures 5 and 6 are details showing, in section through a vertical plane, the assembly of the end of the tube to the manifold, respectively before and after flaring of the

  free part of the tube located beyond the insert.

  FIG. 1 illustrates the general structure of a heat exchanger for a motor vehicle, with a bundle of parallel tubes 10. These tubes are joined on each side by end blocks 12 defining internal volumes communicating with the tubes 10 so to impose a predetermined fluid circulation configuration in

the heat exchanger.

  Each end block 12 comprises, in a manner known per se, a plate 14 or "manifold" provided with orifices 16 receiving the ends of the tubes 10 of the bundle, plate with which is associated a container-shaped element or " fluid box "defining with the manifold one or more volumes into which the bundle tubes open. The end blocks also ensure the inlet and outlet of the fluid to be cooled, by means of corresponding conduits 20 communicating with the internal volume of

the fluid box 18.

  The invention relates to the particular case where the tubes 10 are made of a thermoplastic material, for example by extrusion and / or thermoforming. It is known to obtain by this technique tubes of very flat shape, therefore with a very large exchange surface for each tube, which possibly eliminates the presence of fins

between adjacent tubes.

  The manifold 14 and the fluid box 18 can also be made of such a thermoplastic material, which allows easy assembly by gluing and / or welding, according to

  techniques in themselves known.

  The thermoplastic material considered is for example a polyamide 6-6, a material which lends itself easily to all the usual techniques of extrusion, forming, etc., for example to allow the realization of the tube from a

extruded film.

  The assembly of parts of this material can be obtained

  easily and safely, especially in terms of water

  chewiness, by the various known techniques of welding (heat sealing, ultrasonic welding) and / or bonding (with the addition of external adhesive or, advantageously, with an adhesive already incorporated into the material and which can be expressed

  by heating and pressurizing the parts).

  These very flat tubes, the section of which can present typical-

  ment a length / width ratio of the order of 20/1, are however easily subject to flattening under low stress, due to this shape and the nature of the material. In particular, at the time of assembly, even slight deformation of the tubes can have the effect of poor attachment to the manifold plate, with for

  obvious consequence of a leak in this place.

  To remedy this drawback, the invention proposes, as illustrated in FIG. 2, to associate the tube 10 with each of its

  ends 22 an insert, hereinafter referred to as "in-

  serves ", housed at each end of the tube and allowing to stiffen the latter in particular at the place where it will be connected

  to the manifold of the end block.

  In the first embodiment, illustrated in FIGS. 2 and 3, the insert 24 also serves as an intermediate part between the end 22 of the tube 10 and the orifice 16 of the manifold 14, the connection of the different parts being ensured by bonding, respectively from the insert to the tube and from the manifold to the insert. At the time of manufacture, after obtaining the tube 10, the latter is provided at each of its ends with an insert 24, for example by fitting with tight fit of a portion 26 with inclined wall of the insert in a flare counterpart of the end 22 of the tube, up to the stop

  the end 22 against a shoulder 28 of the insert.

  The tubes fitted with their respective inserts are then mounted one by one, or by subassemblies, on the common manifold 14. The insert advantageously comprises an inclined end 30 introduced into a housing of homologous shape of the opening 16 of the manifold 14 The assembled assembly is then heated to weld and / or glue the various parts, thus achieving their mechanical connection and ensuring their tightness. To reinforce the stiffening effect of the insert, it can be provided with parallel transverse partitions 32 (FIG. 2) defining channels parallel to the direction of circulation of the fluid (therefore only slightly disturbing the flow of the latter from a mechanical point of view

  fluids) and providing excellent structural rigidity

  real part with a minimum of material.

  Figures 4 to 6 illustrate a second embodiment in which the insert, here referenced 34, is fully introduced into the tube 10, unlike the embodiment of Figures 2 and 3 o the insert 24 was only partially introduced into the tube and presented a part

emerging connected to the collector.

  In this configuration, the insert, which always provides rigidity at the end of the tube, defines a free part 36 at the end of the tube (Figure 5). The ends of the tubes are then introduced into the openings 16 of the manifold 14, then the free parts 36 are deformed so as to flare them and come to press them against an inclined homologous wall 38 of the opening of the manifold (as illustrated in on the Figure 6), to allow a connection

  direct from the tube to the collector by gluing and / or welding.

  Here again, the insert 34 advantageously comprises transverse partitions 42 (FIG. 4) similar to the partitions 32 of

  insert 24 of the first embodiment.

  Finally, in one or the other embodiment, to optimize the heat exchange, the assembly of the tubes to the manifold can be done with a slight offset in the direction of the largest dimension of the sections of the tubes, as illustrated Figure 4 o this offset has a pitch of the order of half the width of the channel defined by two successive transverse partitions 42, in a direction perpendicular to the

plan of these partitions.

Claims (12)

Claims   1. Motor vehicle heat exchanger, compressor   nant a bundle of parallel tubes (10) of preformed thermoplastic material and two end blocks (12) joining these tubes, each end block comprising a manifold (14) in the form of a plate provided with orifices (16) in which seal the ends of the bundle tubes, and a fluid box (18) sealed by the collector to define an internal volume therewith, characterized in that it comprises at each end of the tube at least one insert (24; 34)   partially in the tube so that the outer surface   peripheral peripheral of the insert cooperates with a homologous peripheral internal surface of the tube by stiffening this   last in the vicinity of its outlet.   2. Heat exchanger according to claim 1, character-   risé in that the cross section of the tubes is oblong or elongated and that the insert (24; 34) has a contour homologous to this section and is provided in its internal region with transverse partitions (32; 42)   stiffening joining the opposite sides of this contour.   3. Heat exchanger according to one of claims 1 and   2, characterized in that the insert (24) is partially introduced into the tube, its emerging part (30) cooperating   with the homologous orifice (16) of the manifold (14).   4. Heat exchanger according to claim 3, character-   risé in that the tube (10) and the insert (24), as well as the insert (24) and the manifold (14), are integral   together and tightly by bonding or welding.   5. Heat exchanger according to one of claims 3 and   4, characterized in that the emerging part (30) of the insert has an outer peripheral surface portion inclined axially inwards which cooperates with a   homologous inclined surface of the collector.   6. Heat exchanger according to one of claims 3 to   , characterized in that the part (26) of the intro insert   pick in the tube has a portion of peripheral surface   that exterior inclined axially inwards which cooperates with a homologous flaring (22) of the tube.   7. Heat exchanger according to one of claims 1 and   2, characterized in that the insert (34) is completely inserted into the tube, the wall of the tube then being clamped between the outer surface of the insert and a surface   interior homologous to the orifice (16) of the manifold (14).   8. Heat exchanger according to claim 7, character-   risé in that the collector (14) and the tube (10) are joined together and tightly by gluing or welding.   9. Heat exchanger according to one of claims 7 and   8, characterized in that the tube has, in a region of its length situated between the insert and the outlet of the tube, a flared part (40) cooperating with a homologous flaring of the manifold orifice.   10. A method of manufacturing a heat exchanger, characterized in that it comprises the steps consisting in:   a) making a plurality of tubes (10) of thermo-material   preformed plastic, b) at least partially introducing into the tubes, at each of their ends, an insert (24; 34) stiffening these tubes in the vicinity of their outlets, and c) assembling the various tubes in bundles and bringing them together   by end blocks (12) each comprising a collection   tor (14) of thermoplastic material in the form of a plate joining together the corresponding ends of the beam tubes.   11. Method according to claim 10, characterized in that, in step b), the insert (24) is partially introduced into the tube (10) its emerging part (30) cooperating with it the homologous orifice (16 ) of the manifold (14), and the assembly step c) is carried out by gluing or welding the tubes   to the inserts, and inserts to the collector.   12. Method according to claim 10, characterized in that, in step b), the insert (34) is completely introduced into the tube (10) beyond the outlet of the latter, and step c) assembly is carried out by flaring the free projecting part (40) of the tube against a homologous flare of the orifice (16) of the manifold (14), then gluing or welding the tubes to the collector.