WO2004076930A2

WO2004076930A2 - Device for transferring heat

Info

Publication number: WO2004076930A2
Application number: PCT/EP2004/001792
Authority: WO
Inventors: Ewald Fischer; Matthias Jung; Wolfgang Seewald; Werner Storz
Original assignee: Behr Gmbh & Co. Kg
Priority date: 2003-02-27
Filing date: 2004-02-24
Publication date: 2004-09-10
Also published as: EP1601915B1; DE502004002957D1; JP2006519352A; JP4555280B2; US20070163766A1; WO2004076930A3; ATE354769T1; DE20303139U1; EP1601915A2

Abstract

The invention relates to a device for transferring heat and especially an evaporator, especially for the air-conditioning system of a vehicle comprising at least one collecting tank comprising at least two collecting chambers.

Description

Heat transfer device

The invention relates to a device for heat transfer and, in particular, to an evaporator, in particular for a vehicle air-conditioning system, with at least one header tank, which has at least two header chambers. Although the invention is described below with reference to the evaporator of a vehicle air conditioning system, it should be pointed out that this purpose is not to be understood as limiting, but that the heat exchanger according to the invention can also be used in other air conditioning systems and the like.

Such heat transfer devices mentioned above are known from the prior art. From DE 198 26 881 A1 a heat exchanger is known which has a collecting box made of sheet metal, which is formed from a prepared circuit board. The collecting box is divided in the longitudinal direction into two chambers, the ends of two rows of flat tubes arranged one behind the other, through which the air to be cooled flows, are inserted into the bottom of the collecting box. The collecting chambers have side walls, the adjacent side walls of the two collecting chambers being aligned parallel to one another and lying directly against one another and being soldered there to one another and to the floor in order to ensure the tightness of the collecting box. A heat exchanger is known from DE 100 56 074 A1, in which the connection flanges are not arranged at the ends of the header tank as is usual, but on a longitudinal side section, as a result of which a simple construction can be achieved without additional components. In such a heat exchanger, too, the adjacent side walls of the two chambers are aligned parallel to one another in a planar manner and are soldered to one another and to the bottom of the header tank.

A disadvantage of the heat exchangers known in the prior art is that relatively narrow manufacturing tolerances have to be observed in order to keep the rejects low.

It is therefore the object of the present invention to provide a heat exchanger in which larger manufacturing tolerances are possible.

The object of the present invention is achieved by claim 1.

Preferred developments are the subject of the dependent claims.

A heat exchanger according to the present invention can be used in particular as an evaporator for a vehicle air conditioning system. The heat exchanger comprises at least one header box with at least two header chambers, essentially each header chamber being essentially delimited by a bottom device and an upper part device. The upper part device of a first collecting chamber comprises a first middle side wall, and the upper part device of the second collecting chamber comprises a second middle side wall.

The first middle side wall is arranged at least over a section adjacent to the second middle side wall.

At least over part of a height of the header tank, a lateral distance between the first middle side wall and the second middle side wall increases with the height above the floor device. The heat exchanger according to the invention has many advantages.

Characterized in that the collecting box has at least two collecting chambers, which are arranged at least over a portion next to each other, it is possible to provide a double-row evaporator, wherein the ^• through the evaporator passing air only in a first set of flat tubes and then in a second series of Flat tubes pass by.

Each collecting chamber is delimited by the bottom device and by an upper part device, here the term upper part device means the limitation of the collecting chamber above the bottom device. The upper part device can have one or two side walls and a top wall or also a continuously curved (eg semicircular) Wall or the like include.

Because the collecting chambers are arranged next to one another and the "middle" side walls, that is to say the right side wall of the left collecting chamber and the left side wall of the right collecting chamber, increase their lateral distance from the floor device, a gap which increases from the floor device is achieved ,

This results in a better flux transport and consequently a better activation of the solder in the gap and thus. the middle side walls and the floor equipment when the header box is soldered.

“Middle” side walls here mean the side walls lying next to one another (also “contact side walls” since these are almost or possibly partially in contact with one another) of the first and second collecting chambers. Accordingly, the outer side walls in a two-chamber collection box are the side walls outside, that is to say the side walls, next to which no collection chamber is arranged. If a collecting box has three collecting chambers, both side walls of the collecting chambers are so-called "middle" side walls in the middle, since a further collecting chamber is arranged adjacent to each. A gap to be narrowed towards the base device favors the flux transport towards the inside when soldering to the base device, especially in the warm-up phase. In the case of conventional, that is to say parallel, side walls, the distance between the parallel walls must be kept very precisely, since the distance influences the capillary effect.

With a heat exchanger according to the invention, the manufacturing tolerances to be complied with are smaller, since the distance of the gap changes continuously over the height and thus, even with less precise manufacturing tolerances at a suitable distance, there is a gap size which has a positive capillary effect.

The more favorable manufacturing tolerances can lower the costs for the manufacturing process, which also results in a lower reject rate. Depending on the coordination between the accuracy of the manufacturing tolerance and the costs for the manufacturing process, the reject rate can be chosen to be low, or the reject rate is somewhat higher than a possible minimum, although the manufacturing costs decrease overall due to the more favorable manufacturing tolerances.

In a preferred development of the invention, the lateral distance between the first and the second middle side wall or the contact side walls is essentially V-shaped. A continuous and strictly monotonously increasing distance curve is advantageous, since this always results in a suitable lateral distance essentially independent of the manufacturing tolerances.

In a further preferred development of the invention, at least one stability device or a distribution device is arranged on at least one side wall. A stability device increases stability. A distribution or a stability device can be provided on a central or also on an outer side wall.

It is also possible for one or more distribution or stability devices to be located on one or both of the middle side walls and / or are arranged on one or more outer side walls. The distribution or stability devices can be provided in the interior of the collecting chambers and / or in the room outside or extend inside and outside the collecting chambers.

A longitudinal direction on at least one distribution or stability device is preferably oriented essentially perpendicular to the floor device, so that the distribution or stability device preferably extends approximately perpendicular to the surface of the floor device.

In a preferred development, at least one distribution or stability device is designed as a depression device and can be shaped, for example, as a channel device or notch or the like.

It is possible for the depression device to be a depression in the outer surface of a side wall of a collecting chamber, which extends, for example, from the floor device to a certain height above the floor device. The deepening device can, for example, be V-shaped or U-shaped, the width of the U, ie the width between the legs of the U, being many times greater than the depth of the U.

For example, ratios of depression width to depression height of 1:10 to 100: 1 are possible, the range preferably being from about 1: 5 to 80: 1. In the case of notch-like recesses, a ratio in the range of 1: 1 is preferred, while in particular in the case of groove-like recesses, considerably larger values are also possible.

In particular, but not only, indentation devices or stability devices produced by non-cutting manufacturing processes in general increase the stability in the lateral direction of the side walls and thus of the collecting chambers as a whole. Distributors facilitate the distribution of the flux and solder.

This also results in an improved manufacturing process, since the manufacturing tolerances can be reduced with a constant or even lower reject rate.

Recessing devices on the outer sides of the central side walls or the contact walls are advantageous, since this ensures that a capillary gap is formed between the side walls or legs of the collecting chambers, which can also be formed over a large area, depending on the width of the depression device. Capillary gaps of this type, that is to say both narrow and large areas, promote the flux transport when soldering, so that a reliable solder connection between the side walls and the base device can be achieved.

In typical flat tube evaporators for automotive air conditioning systems, the height of the depressions can be between approximately 0.05 and 0.4 mm, the width in the range between 0.05 mm and 8 or 10 mm or even more. It should be pointed out here that these figures refer only to one specific example. With such and also with other flat tube evaporators or evaporators in general, both smaller and larger dimensions are possible.

In a further preferred development of the invention, at least one distribution device or at least one stability device projects outwards, preferably at least one distribution or stability device projecting outwards from a side wall of at least one collection chamber. Particularly preferably, at least one stability device projects outwards on one of the middle side walls or the contact side walls, so that the lateral distance (or gap) between the two middle side walls is reduced at the location of a stability device.

At least one distribution or stability device is preferably designed as a bead device, which is particularly preferably manufactured without cutting. Particularly preferably, a plurality of distribution or stability devices are preferably distributed in an evenly spaced manner over at least one section or over the entire length of at least one collection chamber. see, wherein the stability devices can be arranged alternately on the outwardly facing surfaces of the middle side wall of the first collecting chamber and the middle side wall of the second collecting chamber. It is also possible that all stability devices are only provided on a central side wall or on a collecting chamber.

In a preferred development of the invention, a depth of a distribution or stability device increases with the distance from the floor device. For example, the depth, that is to say the vertical distance from the outer dimension of the stability device to the side surface, in the vicinity of the floor device can be one third of the maximum depth. In the case of stabilization devices projecting outwards, it is then the height relative to the side wall, while in the case of depression devices, the depth of the depression device relative to the sidewall is meant as stability devices.

In a preferred development of the invention, a depression is provided in the bottom device in a contact area of the middle side walls with the bottom device, this depression being able to be designed, for example, as a bottom bead, for example to represent a guide for the ends of the side walls.

In a further preferred development of the invention, at least one flat tube has a smaller wall thickness in the region of a flank than in a region of the curve or radius.

This development is very advantageous, since the special tube geometry on the flat tube with the increased radius means that a low flat tube weight with high strength can be achieved. This results in a lighter pipe and thus a lower overall weight. As a result, lower overall costs can also be achieved. The wall thickness of the flat tube is preferably 10% or 20% or more less in the region of the flanks than in a region of the radius.

The ratio of the wall thicknesses in the range from wall thickness in the radius to wall thickness on the flank is preferably in a range from approximately 1.2 to 3 and particularly preferably in a range between approximately 1.4 and 2.

In one embodiment of the invention, the wall thickness of the flat tube in the region of the flanks can be approximately 0.2 to 0.4 and preferably 0.3 mm at least at one point. Especially in this embodiment, the wall thickness of the flat tube in the radius area is between 0.4 and 0.7 mm and preferably about 0.5 to 0.6 mm in at least one place.

By reducing the wall thickness in the area of the flanks, a considerable part of the weight of the flat tubes is saved overall.

In a preferred development of the invention, at least one upper part device is manufactured in one piece, so that the middle and the outer side wall and the upper ceiling wall of the upper part device are made in one piece.

In a preferred development of the invention, at least one top part device or two top part devices are made in one piece with the bottom device. It is then possible to use a collecting box, which comprises two collecting devices, to produce the essentially entire collecting box in one piece from a prefabricated circuit board, for example by bending.

In order to accomplish the subdivision of the collecting box into at least two chamber devices, it is possible to design the collecting box in one piece in such a way that the side elements adjoining the bottom element are curved in the direction of the bottom element, and are finally connected to one another and to the bottom element.

For this purpose, it is necessary to permanently connect the side elements to one another and to the base element, for example by soldering. That's the way it is z. B. known to execute the side elements such that they run substantially perpendicular to the bottom element, and can therefore be soldered to one another and to the bottom element.

The base device can be prepared in such a way that it has the desired dimensions or also the required openings or cutouts for the connection to the side or top part devices. Since the collecting box can be brought into its final shape before the final soldering, the device is also very strong before the soldering.

In a preferred development of the invention, at least one connection opening of the heat transfer is arranged on a longitudinal side section of the collecting tank, it also being possible for a connection opening to be arranged on a front side of a collecting tank or for both connection openings to be arranged on the front side or on one or both long sides of the Collection box are provided.

In a preferred development of the invention, the collecting tank is connected to two rows of heat transfer tubes arranged one behind the other. It is also possible that three or more rows of heat transfer pipes are connected to the header box. A collecting chamber is preferably provided for each row of heat transmission tubes, but it is also possible that a collecting chamber is provided for, for example, two (or three or more) rows of tubes of heat transmission tubes.

In a preferred development, at least one side wall is provided with at least one tab device or the like, which is inserted into recesses in the base devices. The insertion point can be caulked. The caulking point can also be punched in the guide bead after the collector has been formed. Caulking the insertion point before loosening offers the advantage of a firm connection of the parts to be soldered. A cover plate is preferably arranged on at least one and particularly preferably on both ends of the collecting chambers.

Furthermore, it is preferred that a guide bead is provided for the partition wall, so that the partition wall cannot tilt substantially and there is an improved contact of the partition wall with the collector due to the U-shaped border. A U-shaped border or bead in the area of the contact surfaces of the side walls or legs also results in larger soldering areas.

The combination of, for example, a V-shaped gap between the inner side walls of the two collecting chambers and further distribution or stability devices in the form of protruding beads or depressions results in the possibility of a larger tolerance field, so that in a specific example the gap distance at the open end of the V- Gap can vary by up to 50% and can move between 0.15 and 0.23 mm, while at the lower end of the bottom device it lies between 0.05 and 0.11 mm.

The stability devices ensure that there is always a sufficient capillary gap for flux transport, regardless of manufacturing-related shape deviations.

Gaps that are too small or too large in conventional heat exchangers hinder the flux transport, especially in the warm-up phase, so that tighter manufacturing tolerances have to be observed or a larger scrap is accepted.

Further advantages and possible applications of the invention are described below with reference to the drawings. In it show:

Figure 1 is a perspective view of a heat exchanger according to the invention according to a first preferred embodiment; FIG. 2 shows a partial view of the collecting box from the exemplary embodiment according to FIG. 1;

Figure 3 is a partial view of an upper part of the header box of Figure 2;

Figure 4 shows the collecting box of Figure 1 in section;

Figure 5 shows the detail A from Figure 2;

Figure 6 is a schematic side view of part of the header of the heat exchanger of Figure 1;

FIG. 7 shows a schematic illustration of a second exemplary embodiment of a collecting box;

Figure 8 is a schematic side view of a third embodiment of a header of a heat exchanger;

FIG. 9 shows part of a sectioned top view A-A of the collecting box according to FIG. 8;

Figure 10 shows a flat tube according to the invention in section; and

Figure 11 shows another embodiment of an inventive

_^ Heat exchanger in side view.

A first exemplary embodiment of the heat exchanger according to the invention, which is designed as an evaporator for a vehicle air conditioning system, is now illustrated with reference to FIGS. 1 to 7.

The heat exchanger shown in perspective in FIG. 1 comprises an upper header box 2, a lower header box 11 with heat transfer tubes 9 arranged therebetween. The upper collecting box 2 comprises a first collecting chamber 3 and a second collecting chamber 4 parallel to it, the end faces of which are closed with covers 5 ^• . The inlet 6 and the outlet 7 for the cooling medium to be evaporated are provided on a longitudinal side 8 of the first header tank 3.

At this point, however, it should be pointed out that the inlet and outlet can not only be provided on one long side 8 of one or both collecting chambers (ri) of the collecting box 3, but that it is also possible for the inlet to be provided on a long side of the first collecting box and the drain on one long side of the second collecting tank.

Likewise, it is also possible for the inlet and outlet to be provided on the end faces of one or both collecting chambers, as is illustrated in the exemplary embodiment according to FIG. 11, with the inlet and outlet being provided on the end sides of the two collecting chambers of the collecting box.

In the detail shown enlarged in FIG. 2, the bottom 12 of the collecting box 2 and an upper part 13 of the first collecting chamber 3 are shown.

In the exemplary embodiment, the upper part 13 of the first collecting chamber 3 is made in one piece with the bottom 12 of the collecting box. The second upper part 23 can also be made in one piece with the base 12.

The upper part 13 of the first collecting chamber 3 comprises an outer side wall 14, an upper wall 16 and a middle side wall 15, which in the exemplary embodiment is arranged approximately in the middle of the collecting box 2.

The upper part 13 with the outer side wall 14, the middle side wall 15 and the upper side wall 16 is formed by bending over a lateral edge area of the base 12, the transition between the individual wall areas being fluid. The "middle" side wall 15 lying in the middle of the base 12 is thereby separated by the end of the one-piece component. forms. By using bending aids 100, 100 ', such as preferably beads or embossments, the material can be bent more easily and with better control at the points to be bent. It is expedient for the bending aid element to reduce the wall thickness, so that the bending process can be carried out more easily at this point. According to the invention, the bending aid element can be introduced into the wall inside the collecting box and / or outside the collecting box.

FIG. 2 shows that the bottom device and the top part device are made from one part, at least at locations in which the bottom device and the top part device and / or the top part device and a side wall (see FIG. 4) adjoin one another, bending aid elements 100, 100 ', 101, 101 'are provided. The bending aids are areas with reduced wall thickness, such as preferably one or a plurality of lines and / or points.

The reduction in wall thickness of the bending aid elements is preferably in the range from 10% to 50% compared to the normal wall thickness. It is particularly expedient if the reduction is in the range from 20% to 40% compared to the normal wall thickness.

As can be seen in FIG. 3, the end of the middle side wall 15 has tabs 18 which protrude beyond the end of the middle side wall 15 and are inserted into corresponding recesses 19 in the bottom region of the collecting box during manufacture. There, the tabs 18 are preferably caulked to the base 12, so that the upper part 13 and the central side wall 15 are firmly seated to the base element 12. This ensures good and permanent soldering of the individual elements to one another, since no parts can move against one another during the soldering process. This is also shown enlarged in FIG. 5.

In the bottom 12 of the collecting tank 2, pipe receptacles 17 are provided for the flat pipes 9 to be connected. In an end region of the first collecting chamber 3 and the second collecting chamber 4, overflow openings 21 are provided in the middle side walls 15 and 25, which overflow the refrigerant from the first collecting chamber 3 to the second collecting chamber 4 or, depending on the embodiment, in the reverse direction, to enable.

FIG. 4 shows a side view of the sectioned collecting box 2, in which tabs 18 are inserted into recesses 19 in the base 12 in the contact area with the central side walls 15 and 25 and caulked there in order to facilitate soldering. Overall, the collecting box 2 has a height 69.

FIG. 6 shows a schematic side view, not to scale, of the contact area of the middle side wall 15 and the middle side wall 25 with the bottom 12 of the collecting tank 2. While a lateral distance 33 is provided at the point of contact with the floor 12, there is a lateral distance 32 of the central side walls at a height distance 29 from the floor 12.

In the exemplary embodiment, a distance of 0.1 mm is provided for the distance 33, and at a height 29 of approximately 10 mm, the distance 32 is approximately 0.3 mm, so that the opening angle between the middle walls 15 and 25 is approximately 1 ° is. The V-shaped gap 22 enables reliable capillary action when soldering.

At a height 29 above the floor device 12 there is a kink 10 in the first collecting chamber 10 and a kink 20 in the second collecting chamber 4, as can also be seen in the not so schematic drawing according to FIG. While the outer side walls 14 and 24 merge into ceiling walls 16 and 26 without a recognizable transition point, in the exemplary embodiment the middle side walls 15 and 25 are clearly offset from the ceiling walls 16 and 26 at the kink 10 and 20, respectively. FIG. 7 shows a further exemplary embodiment of a collecting tank 2, in which the same parts are provided with the same reference symbols. This collecting box 2 also comprises a first collecting chamber 3 and a second collecting chamber 4, each of which comprises middle side walls 15 and 25, respectively.

In this embodiment, a bead 31 or a plurality of beads 31 are provided in the V-shaped gap 22, which are arranged at regular intervals along the length of the collecting tank 2.

The individual beads 31 can, for example, only be provided on the outside of the middle side wall 25, but it is preferred that they are provided alternately on the outside of the middle wall 15 and the middle wall 25. Due to technical production conditions, the beads can, however, only be provided on an outer side of a central side wall (15 or 25).

The outer shape of the bead 31 is also substantially V-shaped, so that it has a smaller depth in the region of the bottom 12, ie. H. has a smaller distance from the outside of the wall than in the upper area at the distance 29 at the height of the kink point 20. The dimensions of the bead 31 can be adapted to the gap 22 such that the depth in the bottom area is approximately 0.1 mm and is approximately 0.3 mm in height 29 above floor 12. The height 59 of the bead does not have to, but can match the height 29 of the break points 10, 20.

However, other dimensions are also possible, so that these figures are only to be understood as examples. In particular, it is possible for the dimensions of the bead to be a certain percentage smaller than the dimensions 32 and 33, respectively, which define the intended spacing of the side walls 15 and 25. Then the beads guarantee a minimum distance.

In addition to the exemplary embodiment according to FIGS. 1 to 6, in the exemplary embodiment according to FIG. 7 there is in the contact area of the side walls 15 and 25 with the bottom 12, a depression 30 with a depth 34 of the exemplary embodiment 0.1 mm is provided. The depression 30 facilitates the manufacture of the collecting tank 2, since the ends of the side walls 15 and 25 are guided into the depression 30 before soldering, and this results in a lateral hold.

The beads 31 create large capillary gaps which allow the flux and the solder to be distributed well. Furthermore, the beads 31 fulfill the function of a spacer between the outer sides of the middle side walls 15 and 25. It is reliably ensured that the distance is not too small to ensure a reliable soldered connection.

In the exemplary embodiment according to FIGS. 8 and 9, stability devices designed as channels 35 are provided. The grooves 35 have a depth 36, which in the exemplary embodiment is 0.1 mm. Analogously to the exemplary embodiment with the beads 31 according to FIG. 7, in the exemplary embodiment with the channel-like depressions 35 according to FIGS. 8 and 9, the depth of the channels can change with the distance from the bottom 12 of the collecting tank.

In this exemplary embodiment, too, the surface profiling that is created by the channels 35 gives the upper part (s) 13 or 23 of the two collecting chambers 3, 4 stability.

The grooves 35 fulfill the function of distributing flux and solder, so that a secure connection of the side walls 15 and 25 to the floor 12 is made possible.

As in the previous exemplary embodiment, a depression 30 is provided in the contact area of the middle side walls 15 and 25 and the bottom 12.

FIG. 9 shows a sectional top view AA from FIG. 8. The groove-shaped depressions 35 can be seen in FIG. 9 from the top view. In this exemplary embodiment, the groove-shaped depressions 35 are arranged on both middle side walls 15 and 25.

In this exemplary embodiment, the channels were created by compressing the material during the bending process for the production of molds, so that the depressions shown result on each of the outer sides of the central side surfaces.

A plurality of depressions are provided, which here are also at the same distance 61 from one another in the middle side walls. The depressions on the side wall 15 are laterally displaced relative to the depressions on the side wall 25 by an amount 62 which preferably corresponds to half the distance 61.

Also in the exemplary embodiment according to FIGS. 8 and 9, the distance 33 in the region of contact of the side walls with the floor, the distance between the two side walls from each other is approximately one third of the distance at the height 29 of the break points 10 and 20.

FIG. 10 shows a flat tube 40 for a heat exchanger for one of the exemplary embodiments.

The flat tube has external dimensions perpendicular to the flow direction of a refrigerant with a length 41 of 30 mm and a width 42 of

3 mm. However, other dimensions are also possible. In the area of the radius or the curves 43, the wall thickness has a dimension 44 of 0.55 mm, while in the area of the flanks 49 there is a significantly smaller wall thickness 45 of 0.3 mm.

The flat tube is divided across the width into a number of 8 flow chambers, the middle 6 having an inner width of 3.2 mm. The partitions 46 have a width 47 of 0.3 mm. Due to the considerably different wall thicknesses from the radius area to the flank area, a significantly lower overall weight of the flat tube is achieved overall, since there is a relatively large wall thickness in the area of the radii 43, while such a wall thickness is not required in the area of the flanks.

FIG. 11 shows a side view of a heat exchanger 60, which likewise comprises header boxes 2 and 11.

With partitions 50 and 51, the collecting tanks 2 and 11 are divided into a plurality of longitudinal sections, so that there is a meandering flow path of the evaporation medium over the heat exchanger 60.

In this exemplary embodiment, the connections 6 and 7 are provided for inlet and outlet on the end faces of the collecting tank 2 at the collecting chambers 3 and 4.

With regard to the further design of the heat exchanger and in particular the design and the flow conditions of the header tanks and the rest of the heat exchanger, reference is made to DE 19 82 688 A1 by the applicant and in particular column 1, line 1 to column 6, line 16 in connection with the Figures 1 to 6 referenced, the disclosure content is included here.

Likewise, further details of the heat exchanger can also be implemented according to the applicant's DE 100 56 074 A1, as described there in column 1, line 1 to column 8, line 22 with reference to FIGS. 1 to 5, the content of which is also shown in the disclosure content of this application is included.

Claims

Expectations

1. Heat exchanger (1), in particular evaporator for a vehicle air conditioning system, with at least one collecting box (2) with at least two collecting chambers (3, 4), essentially each collecting chamber (3,

4) is essentially delimited by a bottom device (12) and an upper part device (13), the upper part device (13) of a first collecting chamber (3) comprising a first middle side wall (15) and the upper part device (23) of a second collecting chamber ( 4) comprises a second central side wall (25), wherein the base device and the upper part device are made from one part, wherein bending auxiliary elements are provided at least at points in which the base device and the upper part device and / or the upper part device and a side wall adjoin one another.

2. Heat exchanger according to claim 1, characterized in that the bending auxiliary elements are areas with reduced wall thickness, such as preferably individual or a plurality of lines and / or points.

3. Heat exchanger according to claim 1 or 2, characterized in that the bending auxiliary elements are introduced by impressions.

4. Heat exchanger according to claim 1, 2 or 3, characterized in that the bending auxiliary elements have a wall thickness reduction in the range of 10% to 50% compared to the normal wall thickness.

5. Heat exchanger according to claim 1, 2 or 3, characterized in that the bending auxiliary elements have a wall thickness reduction in the range of 20% to 40% compared to the normal wall thickness.

6. Heat exchanger according to one of the preceding claims, characterized in that the first central side wall (15) is arranged at least over a section adjacent to the second central side wall (25), with over at least part of a height (69) of the Collection box (2) a lateral distance of the first middle side wall (15) from the second middle side wall (25) increases with the height above the floor device (12) or remains the same.

7. Heat exchanger according to claim 6, characterized in that the gap (22) between the first and second central side walls (15; 25) is essentially V-shaped.

8. Heat exchanger according to claim 6 or 7, characterized in that at least one stability device is arranged on at least one side wall (14, 15; 24, 25) in order to increase the stability.

9. Heat exchanger according to claim 8, characterized in that a longitudinal direction of at least one stability device (31, 35) is aligned essentially perpendicular to the base device (12).

10.Heat exchanger according to at least one of claims 8 or 9, characterized in that at least one stability device (35) is designed as a recess device (35).

11. Heat exchanger according to at least one of claims 8 to 10, characterized in that at least one stability device (35) is essentially shaped as a channel device (35).

12. Heat exchanger according to at least one of claims 8 to 11, characterized in that at least one stability device (35) is essentially shaped as a notch (35).

13. Heat exchanger according to at least one of claims 8 to 12, characterized in that at least one stability device (31) projects outwards.

14. Heat exchanger according to claim 13, characterized in that at least one stability device (31, 35) is designed as a (31) beading device.

5. Heat exchanger according to at least one of claims 8 to 14, characterized in that a depth (36) of at least one stability device (31, 35) increases with a distance (29) from the bottom device (21).

16. Heat exchanger according to at least one of the preceding claims, characterized in that a ^bottom recess (30) is arranged in a contact area of the middle side walls (15, 25) with the bottom device (12).

17. Heat exchanger according to at least one of the preceding claims, characterized in that at least one flat tube (40) has a smaller wall thickness (42, 45) in the area of a flank (49) than in an area of a radius (43).

18. Heat exchanger according to claim 17, characterized in that at least one flat tube (40) in the area of the flanks (49) has a wall thickness (45) that is at least 20% smaller than in an area of the

Radius.

19. Heat exchanger according to at least one of claims 17 and 18, characterized in that at least one flat tube (40) in the area of the flanks (49) has a wall thickness of approximately 0.3 mm at at least one point.

20. Heat exchanger according to at least one of claims 17 to 19, characterized in that at least one flat tube (40) in the area of a radius (43) has a wall thickness (44) of approximately 0.5 mm at at least one point.

21.Heat exchanger according to at least one of the preceding claims, characterized in that at least one upper part device (13, 23) is made in one piece.

22. Heat exchanger according to at least one of the preceding claims, characterized in that at least one upper part device (13, 23) is made in one piece with the base device (12).

23. Heat exchanger according to at least one of the preceding claims, characterized in that at least one connection opening (6,

7) is arranged on a longitudinal side section (8) of the collecting box (2).

24. Heat exchanger according to at least one of the preceding claims, characterized in that the collecting box (2) is connected to two rows of heat transfer tubes (9) arranged one behind the other.

25. Heat exchanger according to at least one of the preceding claims, characterized in that the base device (12) is formed from a prepared circuit board.

26. Heat exchanger according to at least one of the preceding claims, characterized in that at least one side wall (14, 15, 24, 25) is provided with at least one tab (19) which is inserted into a recess (21) in the base device.

27. Heat exchanger according to at least one of the preceding claims, characterized in that an end cover (5) is arranged on at least one front end (38) of at least one collecting chamber (3, 4).

28. Heat exchanger according to at least one of the preceding claims, characterized in that at least one connection opening (6, 7) is arranged on a front end (38) of at least one collecting chamber (3, 4) of the collecting box (2).