METHOD FOR PRODUCING A HEAT EXCHANGER AND HEAT EXCHANGER

Abstract

A method for producing a heat exchanger having tubes, which may be fixed on longitudinal ends in associated openings of a tube plate of a collector, may first include applying an adhesive layer to an outside of each tube by lamination of one of an adhesive layer and an adhesive film. The method may then include inserting each tube with a longitudinal end side tube wall portion into a respective one of the associated openings on the tube plate, wherein the tube wall portion may be bent over in such a manner that it is placed against non-parallel walls of the respective one of the associated openings. The method may further include heating the adhesive layer for adhesive bonding of the tube wall portion of each tube to the non-parallel walls of the respective one of the associated openings.

Claims

1. A method for producing a heat exchanger having tubes, which are fixed on longitudinal end sides in associated openings of a tube plate of a collector, comprising: applying an adhesive layer to an outer side of each tube by lamination of one of an adhesive sheet and an adhesive film; inserting each tubes with a longitudinal end side tube wall portion into a respective one of the associated openings on the tube plate, wherein the tube wall portion is bent over in such a manner that the tube wall portion is placed against non-parallel walls of the respective one of the associated openings; and heating the adhesive layer for adhesive bonding of the tube wall portion of each tube to the non-parallel walls of the respective one of the associated openings.

2. The method as claimed in claim 1, wherein the adhesive layer is heated to a temperature of between 80 C. and 400 C.

3. The method as claimed in claim 1, wherein the adhesive layer is heated for less than 10 minutes.

4. The method as claimed in claim 1, wherein, during the adhesive bonding, the tube wall portion of each tube is pressed against the non-parallel walls of the respective one of the associated openings with a contact pressure of between 0.1 N/mm.sup.2 and 0.7 N/mm.sup.2.

5. The method as claimed in claim 4, wherein at least one of: the contact pressure is produced by an expanding mandrel being pushed into one of the respective tube or the tube wall portion thereof; and the tube wall portion of each tube is deformed by the expanding mandrel being pushed into one of the respective tube or the tube wall portion thereof.

6. The method as claimed in claim 5, wherein the expanding mandrel is additionally used for heating the adhesive layer.

7. The method as claimed in claim 1, wherein at least one of: the adhesive layer is heated in a furnace; and the adhesive layer is cooled after heating the adhesive layer.

8. The method as claimed in claim 1, wherein the adhesive layer is applied with a layer thickness of between 5 m and 500 m.

9. The method as claimed in claim 1, further comprising adhesively bonding a fin structure to an outer side of the tube via the adhesive layer.

10. A heat exchanger comprising tubes each of which is fixed on a longitudinal end side thereof in an associated opening of a tube plate of a collector, said heat exchanger being produced by: applying an adhesive layer to an outer side of each tube by lamination of one of an adhesive sheet and an adhesive film; inserting each tube with a longitudinal end side tube wall portion into the associated opening on the tube plate, wherein the tube wall portion is bent over in such a manner that the tube wall portion is placed against non-parallel walls of the associated opening; and heating the adhesive layer for adhesive bonding of the tube wall portion of each tube to the non-parallel walls of the associated opening.

11. The heat exchanger as claimed in claim 10, wherein the adhesive layer has a layer thickness of between 5 m and 500 m.

12. The heat exchanger as claimed in claim 10, wherein the tubes and the tube plate are produced from different materials.

13. The method as claimed in claim 2, wherein the adhesive layer is heated for less than 10 minutes.

14. The method as claimed in claim 2, wherein, during the adhesive bonding, the tube wall portion of each tube is pressed against the non-parallel walls of the respective one of the associated openings with a contact pressure of between 0.1 N/mm.sup.2 and 0.7 N/mm.sup.2.

15. The method as claimed in claim 14, wherein at least one of: the contact pressure is produced by an expanding mandrel being pushed into one of the respective tube or the tube wall portion thereof; and the tube wall portion of each tube is deformed by the expanding mandrel being pushed into one of the respective tube or the tube wall portion thereof.

16. The method as claimed in claim 15, wherein the expanding mandrel is additionally used for heating the adhesive layer.

17. The method as claimed in claim 2, wherein at least one of: the adhesive layer is heated in a furnace; and the adhesive layer is cooled after heating the adhesive layer.

18. The method as claimed in claim 2, wherein the adhesive layer is applied with a layer thickness of between 5 m and 500 m.

19. The method as claimed in claim 2, further comprising adhesively bonding a fin structure to an outer side of the tube via the adhesive layer.

20. A method for producing a heat exchanger having tubes, each of which is fixed on a longitudinal end side in an associated opening of a tube plate of a collector, comprising: applying an adhesive layer to an outer side of each tube by lamination of one of an adhesive sheet and an adhesive film; inserting each tube with a longitudinal end side tube wall portion into the associated opening on the tube plate, wherein the tube wall portion is bent over in such a manner that the tube wall portion is placed against non-parallel walls of the associated opening; and heating the adhesive layer for adhesive bonding of the tube wall portion of each tube to the non-parallel walls of the associated opening; pressing the tube wall portion of each tube against the non-parallel walls of the associated opening during the adhesive bonding with a contact pressure produced by an expanding mandrel being pushed into the tube or tube wall portion; and deforming the tube wall portion of each tube by the expanding mandrel being pushed into one of the tube or the tube wall portion.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In the drawings, in each case schematically:

[0033] FIG. 1 shows a sectional illustration through a heat exchanger according to the invention in the region of a tube inserted into a tube plate,

[0034] FIG. 2 shows an illustration as in FIG. 1, but with a slightly modified embodiment.

DETAILED DESCRIPTION

[0035] According to FIGS. 1 and 2, a heat exchanger 1 according to the invention has a plurality of tubes 2, of which only a single one is shown in each figure. The tube 2 here is fixed on the longitudinal end side in an associated opening 3 of a tube plate 4 of a collector 5. According to the invention, an adhesive layer 6 is now applied to an outer side of the tube 2 by lamination of an adhesive sheet 7 or of an adhesive film 8. The tube 2 is inserted here with a longitudinal end side tube wall portion 9 in the associated opening 3 on the tube plate 4, wherein the tube wall portion 9 of the tube 2 is bent over in such a manner that said tube wall portion is positioned against non-parallel walls 10 of the associated opening 3. The adhesive layer 6 is heated for adhesive bonding of the tube wall portions 9 to the walls 10 of the openings 3. The openings 3, mentioned here in the plural, result from the fact that only one cutout of the tube plate 4 with a single opening 3 is shown according to FIGS. 1 and 2.

[0036] The adhesive layer 6 here has a layer thickness d of between 5 m and 500 m and is therefore applied extremely thinly here, as a result of which effective electrical insulation is indeed firstly provided. The electrical insulation is of great advantage here in particular in respect of galvanic corrosion, since it opens up the possibility here of forming the tube 2 or the tubes 2 from a different metal than the tube plate 4. If the material selected for the tube 2 has an entirely different coefficient of thermal expansion than the tube plate 4, the layer thickness d of the adhesive layer 6 can be increased and therefore relative movability can be permitted.

[0037] The heat exchanger 1 can be realized in virtually any embodiment, for example as an evaporator, as an engine radiator, as a condenser, as a chiller, as a charge air cooler, as an oil cooler, as a heating element, as a PTC auxiliary heater, as a finned-tube heat exchanger, etc.

[0038] The heat exchanger 1 according to the invention is produced by the previously described and mentioned adhesive layer 6 first of all being applied to an outer side of the tubes 2 by lamination of an adhesive sheet 7 or an adhesive film 8. The tubes 2 are subsequently inserted with a longitudinal end side tube wall portion 9 into a respectively associated opening 3 on the tube plate 4, wherein the tube wall portion 9 of the tube 2 is bent over, for example is expanded or bent at right angles, in such a manner that said tube wall portion is positioned against non-parallel walls 10 of the associated opening 3. If this has taken place, the adhesive layer 6 is heated, specifically customarily to a temperature of between 80 C. and 400 C., for adhesively bonding the tube wall portions 9 to the walls 10 of the openings 3.

[0039] The adhesive layer 6 is heated here for a comparatively short time, in particular for less than 10 minutes, customarily for merely 2-3 minutes, wherein a significant advantage in respect of a cycle time is possible in comparison to previous brazing. In order to be able to achieve as stable a connection and also adhesive bonding of the tube wall portions 9 to the walls 10 of the openings 3 as possible, the tube wall portions 9 are pressed during the adhesive bonding against the associated walls 10 of the openings 3 with a contact pressure of between 0.1 N/mm.sup.2 and 0.7 N/mm.sup.2. Said contact pressure can be produced, for example if the tube wall portion 9 is expanded, by means of an expanding mandrel 11 (cf. FIG. 2) which is pushed into the respective tube 2 or the respective tube wall portion 9 to be expanded. Said expanding mandrel 11 can be equipped with a heating device and can thereby be additionally used for heating the adhesive layer 6. In general, the adhesive layer 6 can, of course, also be heated and therefore activated in a furnace into which the heat exchanger 1 is completely placed.

[0040] Looking further at FIGS. 1 and 2, it is possible to see that a fin structure 12, for example corrugated fins, is adhesively bonded to an outer side of the tube 2 via the adhesive layer 6, wherein said fin structure 12 is intended to bring about an increased heat transmission surface and therefore an improved transfer of heat.

[0041] In order to be able to further reduce the cycle time for producing the heat exchanger 1 according to the invention, it can also be provided that the adhesive layer 6 is cooled after the adhesive bonding and therefore the curing time is reduced.

[0042] With the production method according to the invention and in particular the adhesive layer 6 which is applied according to the invention by lamination, processing of the adhesive can be significantly simplified since machines (pumps, nozzles, valves) which have to be cleaned in a correspondingly complicated manner after the adhesive bonding are no longer required. By means of a comparatively rapid curing time of the adhesive layer 6 of, for example, merely 1-20 minutes, which can advantageously be assisted by, for example, the heatable expanding mandrel 11, the cycle time can also be significantly reduced and, in addition, a high degree of automation achieved. In comparison to brazing, the walls 10 of the openings 3 do not have to be previously degreased by means of PER, as a result of which environmentally hazardous solvents, PER, are no longer required.

[0043] With the method according to the invention and the heat exchanger 1 according to the invention, the following advantages can be achieved: [0044] an adhesive layer which is dry to the touch, no low-viscosity adhesive system, [0045] increased strength at the adhesive bond between tube portion 9 and wall 10 of the opening 3, with simultaneous flexibility of the adhesive because of its material characteristics, dissipation of stress concentrations which arise at the connection in the event of different temperature levels and otherwise lead to premature failure of the connection, [0046] omission of a complicated and expensive surface pretreatment, [0047] possible alignment of the tube 2 relative to the tube plate 4 during and even, under some circumstances, after the adhesive bonding, [0048] prevention of galvanic corrosion by the electrically non-conductive adhesive layer 6, [0049] omission of cleaning for eliminating fluxing agent residues, [0050] omission of expensive brazing, [0051] lower outlay on resources by means of very thin adhesive layers 6, [0052] a combination of a wide variety of materials is possible, [0053] bypassing expensive aluminum alloy which have been required up to now for the brazing.