DE20303139U1 - Device for heat transfer - Google Patents

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

03-B-035 26.02.03 G-I P/G R

BEHR GmbH & Co. KG Mauserstraße 3, 70469 Stuttgart

&igr;&ogr; Device for heat transfer

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 collecting box which has at least two collecting chambers. Although the invention is described below with reference to the evaporator of a vehicle air conditioning system, it should be noted that this intended use 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.

0 Such devices for heat transfer as mentioned above are known from the prior art. DE 198 26 881 A1 discloses a heat exchanger which has a collecting box made of sheet metal which is formed from a prepared circuit board. The collecting box is divided lengthwise into two chambers, with the ends of two rows of flat tubes arranged one behind the other being inserted into the base of the collecting box 5, through which the air to be cooled flows. The collecting chambers have side walls, with the adjacent side walls of the two collecting chambers being aligned parallel to one another and lying directly against one another and being soldered to one another and to the base in order to ensure that the collecting box is leak-tight.

G-IP/Gr-2-

A heat exchanger is known from DE 100 56 074 A1 in which the connection flanges are not arranged on the front ends of the collecting box as is usual, but on a long side section, which allows a simple structure without additional components. In such a heat exchanger, the adjacent side walls of the two chambers are aligned parallel to each other and are soldered to each other and to the bottom of the collecting box.

A disadvantage of the heat exchangers known in the state of the art is that relatively tight manufacturing tolerances must be maintained in order to keep the amount of waste to a minimum.

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 solved by claim 1. Preferred developments are the subject of the subclaims.

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 collecting box with at least two collecting chambers, each collecting chamber being essentially delimited by a base device and an upper part device. The upper part device of a first collecting chamber comprises a first central side wall, and the upper part device of the second collecting chamber comprises a second central side wall.

The first central side wall is disposed adjacent to the second central side wall over at least a portion.

At least over a portion of a height of the collecting box, a lateral distance of the first middle side wall from the second middle side wall increases with the height above the floor device.

03-B-035

26.02.03

G-I P/G r

-3-

The heat exchanger according to the invention has many advantages.

The fact that the collecting box has at least two collecting chambers which are arranged next to one another over at least a section makes it possible to provide a two-row evaporator, wherein the air passing through the evaporator first passes a first row of flat tubes and then a second row of flat tubes.

Each collection chamber is delimited by the base device and by an upper part device, whereby the term "upper part device" is understood here to mean the delimitation of the collection chamber above the base device. The upper part device can comprise one or two side walls and a ceiling wall or also a continuously curved (e.g. semi-circular) wall or the like.

By arranging the collection chambers next to each other and the "middle" side walls, i.e. the right side wall of the left collection chamber and the left side wall of the right collection chamber, increasing their lateral distance from the floor device, a gap that increases from the floor device is achieved.

This results in better flux transport and, as a result, better activation of the solder in the gap and thus on the central side walls and the base assembly when the header box is soldered.

The term "middle" side walls here refers to the side walls that are next to each other (also called "contact side walls" because they are almost or possibly partially in contact with each other) of the first and second collection chambers. Accordingly, the outer side walls of a two-chamber collection box are the outside side walls, i.e. the side walls next to which there is no collection chamber. If a collection box has three collection chambers, both side walls of the collection chambers in the middle are so-called "middle" side walls because there is another collection chamber next to each one.

-4-

03-B-035

26.02.03

G-IP/Gr

A gap that narrows towards the base device promotes the transport of flux during soldering towards the base device inwards, particularly during the warm-up phase. With conventional, i.e. parallel, side walls, the distance between the parallel walls must be maintained very precisely, as the distance influences the capillary effect.

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

The more favorable manufacturing tolerances can reduce the costs of the manufacturing process, while at the same time resulting in a lower scrap rate. Depending on the balance between the accuracy of the manufacturing tolerance and the costs of the manufacturing process, the scrap rate can be set low, or the scrap rate can be slightly higher than a possible minimum, although the more favorable manufacturing tolerances mean that the overall manufacturing costs are reduced.

In a preferred development of the invention, the lateral distance between the first and second middle side walls or the contact side walls is essentially V-shaped. A continuous and strictly monotonically increasing distance profile is advantageous because 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 distribution device is arranged on at least one side wall. A stability device increases stability. A distribution or stability device can be provided on a middle or also on an outer side wall.

It is also possible that one or more distribution or stability devices are installed on one or both middle side walls

· ··· ·
· · • · · φ m 9&psgr; 03-β-035 · · * · ·· * fc w · · 26.02.03
G-IP/Gr -5-

and/or are arranged on one or more external side walls. The distribution or stability devices can be provided in the interior of the collection chambers and/or in the space outside or can extend inside and outside the collection chambers.

Preferably, a longitudinal direction on at least one distribution or stability device is aligned substantially perpendicular to the floor device, so that the distribution or stability device preferably extends approximately substantially perpendicular to the surface of the floor device.

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

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

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

5 In particular, but not only, recesses 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 collection chambers as a whole.

&bgr; ··

03-β-035

26.02.03

G-IP/Gr

-6-

Distribution devices facilitate the distribution of flux and solder.

This also results in an improved manufacturing process, as manufacturing tolerances can be reduced while maintaining or even reducing scrap rates.

Recesses on the outside of the middle side walls or the contact walls are advantageous because they ensure that a capillary gap is formed between the side walls or legs of the collecting chambers, which can also be large-area depending on the width of the recess. Such capillary gaps, i.e. both narrow and large-area ones, promote the transport of flux during soldering, so that a reliable soldered connection can be achieved between the side walls and the base device.

In typical flat-tube evaporators for automobile air conditioning systems, the height of the recesses can be between about 0.05 and 0.4 mm, while the width can be in the range between 0.05 mm and 8 or 10 mm or even more. It should be noted here that these figures only refer to a specific example. For these and 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 protrudes outwards, with at least one distribution or stability device preferably protruding outwards from a side wall of at least one collection chamber. Particularly preferably, at least one stability device protrudes outwards on one of the middle side walls or the contact side walls, so that at the location of a stability device the lateral distance (or gap) between the two middle side walls is reduced.

Preferably, at least one distribution or stability device is designed as a beading device, which is particularly preferably manufactured without cutting.

···· · * 26.02.03

G-IP/Gr-7-

Particularly preferably, a plurality of distribution or stability devices are provided, preferably distributed at equal distances over at least one section or the entire length of at least one collection chamber, wherein the stability devices can be arranged alternately on the outward-facing surfaces of the middle side wall of the first collection chamber and the middle side wall of the second collection chamber. It is also possible for all stability devices to be provided only on one middle side wall or on one collection chamber.

In a preferred development of the invention, a depth of a distribution or stability device increases with the distance from the base device. For example, the depth, i.e. the vertical distance from the external dimension of the stability device to the side surface, can be a third of the maximum depth near the base device. In the case of stability devices that protrude outwards, it is then the height relative to the side wall, while in the case of recessed devices, stability devices mean the depth of the recessed device relative to the side wall.

In a preferred development of the invention, a recess is provided in the base device in a contact area of the middle side walls with the base device, wherein this recess can be designed, for example, as a base bead in order to represent, for example, 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 because the special geometry of the flat tube with the reinforced radius allows a low flat tube weight with high strength. This results in a lighter tube and therefore a low overall weight. This also means lower overall costs can be achieved.

03-β-035

26.02.03

G-IP/Gr

-8th-

Preferably, the wall thickness of the flat tube in the area of the flanks is 10% or 20% or more less than in an area of the radius.

Preferably, the ratio of the wall thicknesses in the range of wall thickness in the radius to wall thickness on the flank is in a range of about 1.2 to 3 and particularly preferably in a range between about 1.4 and 2.

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

By reducing the wall thickness in the flank area, a considerable amount 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 in one piece.

In a preferred development of the invention, at least one upper part device or two upper part devices are manufactured in one piece with the base device. It is then possible to use a collecting box that comprises two collecting devices to produce the essentially entire collecting box in one piece from a prefabricated plate by bending, for example.

In order to achieve the division 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 base element are curved in the direction of the base element and are finally connected to one another and to the base element.

For this purpose, it is necessary to permanently connect the side elements to each other and to the base element, for example by soldering.

03-B-035

26.02.03

G-IP/Gr

&zgr;. For example, it is known to design the side elements in such a way that they run essentially perpendicular to the base element and can therefore be soldered to one another and to the base element over a large area.

The base assembly can be prepared in such a way that it has the desired dimensions or the required openings or recesses for connecting to the side or top assembly. Since the collecting box can be brought into its final shape before the final soldering, the assembly is already very strong before soldering.

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

In a preferred development of the invention, the collecting box is connected to two rows of heat transfer pipes arranged one behind the other. It is also possible for three or more rows of heat transfer pipes to be connected to the collecting box. Preferably, a collecting chamber is provided for each row of heat transfer pipes, but it is also possible for a collecting chamber to be provided for each, for example, two (or three or more) rows of heat transfer pipes.

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 &ogr; firm connection of the parts to be soldered.

·"·'· · &idigr;&idigr; '. . I ; '. 03-β-035

*··"..· 26.02.03

G-IP/Gr-10-

Preferably, a cover plate is 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 essentially tilt and the U-shaped surround results in improved contact between the partition wall and the collector. A U-shaped surround or bead in the area of the contact surfaces of the side walls or legs also results in larger soldering surfaces.

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 range between 0.15 and 0.23 mm, while at the lower end on the floor device it is between 0.05 and 0.11 mm.

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

0 Gaps that are too small or too large in conventional heat exchangers hinder the flux transport, especially during the warm-up phase, so that tighter manufacturing tolerances must be maintained or a larger amount of rejects must be accepted.

Further advantages and possible applications of the invention are described below with reference to the drawings, in which:

Figure 1 is a perspective view of a heat exchanger according to the invention according to a first preferred embodiment;

G-IP/Gr-11-

Figure 2 is a partial view of the collecting box from the embodiment according to Figure 1;

Figure 3 is a partial view of an upper part of the collecting box according to Figure 2; Figure 4 is a sectional view of the collecting box according to Figure 1; Figure 5 is detail A from Figure 2;

Figure 6 is a schematic side view of part of the collecting box of the heat exchanger according to Figure 1;

Figure 7 is a schematic representation of a second embodiment of a collecting box;

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

Figure 9 is a part of a sectional view A-A of the collecting box according to Figure 8;

Figure 10 shows a flat tube according to the invention in section; and Figure 11 shows a further embodiment of a flat tube according to the invention.

Heat exchanger in side view.

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

0 The heat exchanger shown in perspective in Figure 1 comprises an upper collecting box 2, a lower collecting box 11 with heat transfer tubes 9 arranged between them.

G-IP/Gr-12-

The upper collecting box 2 comprises a first collecting chamber 3 and a second collecting chamber 4 parallel thereto, the front sides 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 long side 8 of the first collecting box 3.

At this point, however, it should be noted that the inlet and outlet can not only be provided on a longitudinal side 8 of one or both collection chamber(s) of the collection box 3, but that it is also possible for the inlet to be provided on a longitudinal side of the first collection box and the outlet on a longitudinal side of the second collection box.

It is also possible for the inlet and outlet to be provided on the front sides of one or both collection chambers, as shown in the embodiment according to Figure 11, in which the inlet and outlet are provided on the front sides of the two collection chambers of the collection box.

The detail shown enlarged in Figure 2 shows the bottom 12 of the collecting box 2 and an upper part 13 of the first collecting chamber 3.

The upper part 13 of the first collecting chamber 3 is manufactured here in the embodiment 0 as one piece with the base 12 of the collecting box. The second upper part 23 can also be manufactured as one piece with the base 12.

The upper part 13 of the first collection 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 collection box 2.

By bending a side edge area of the base 12, the upper part 13 is created with the outer side wall 14, the middle side wall and the upper side wall 16, whereby the transition between the individual wall areas is fluid. The "middle" side wall 15 located in the middle of the base 12 is formed by the end of the one-piece component.

· 26 02

G-I P/G r -13-

By using bending aids 100, 100', such as preferably beads or indentations, the material can be bent more easily and with better control at the points to be bent. It is expedient if the bending aid reduces the wall thickness so that the bending process can be carried out more easily at this point. According to the invention, the bending aid can be introduced into the wall inside the collecting box and/or outside the collecting box.

Figure 2 shows that the base device and the upper part device are made from one part, with bending aid elements 100, 100', 101, 101' being provided at least at locations where the base device and the upper part device and/or the upper part device and a side wall (see Figure 4) adjoin one another. The bending aid elements are areas with reduced wall thickness, such as preferably individual or a plurality of lines and/or points.

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

&ogr; As can be seen in Figure 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 base area 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 middle side wall 15 are firmly seated with 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 Figure 5.

In the bottom 12 of the collecting box 2, pipe receptacles 17 are provided for the flat pipes 9 to be connected.

··· 26.02.03

G-IP/Gr

-14-

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, respectively, which allow the coolant to flow from the first collecting chamber 3 to the second collecting chamber 4 or, depending on the embodiment, in the opposite direction.

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

Figure 6 shows a schematic, not to scale side view of the contact area of the middle side wall 15 and the middle side wall 25 with the base 12 of the collecting tank 2. While a lateral distance 33 is provided at the contact point with the base 12, a lateral distance 32 of the middle side walls is present at a height distance 29 from the base 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 is approximately 0.3 mm, so that the opening angle between the middle walls 15 and 25 is approximately 1°. The V-shaped gap 22 enables a reliable capillary effect during soldering.

At a height 29 above the floor device 12, a kink point 10 is provided in the first collecting chamber 10 and a kink point 20 is provided in the second collecting chamber 4, as can also be seen in the not so schematic drawing according to Figure 4. While the outer side walls 14 or merge into the ceiling walls 16 or 26 without a recognizable transition point, in the exemplary embodiment the middle side walls 15 or 25 are clearly separated from the ceiling walls 16 or 26 at the kink point 10 or 20.

·

·" 26.02.03

G-IP/Gr-15-

Figure 7 shows a further embodiment of a collecting box 2, in which the same parts are provided with the same reference numerals. This collecting box 2 also comprises a first collecting chamber 3 and a second collecting chamber 4, which each comprise central side walls 15 and 25, respectively.

In this embodiment, a bead 31 or several beads 31 are provided in the V-shaped gap 22, which are regularly arranged at certain intervals over the length of the collecting box 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 manufacturing conditions, the beads can also be provided only on one outside of a middle side wall (15 or 25).

The external shape of the bead 31 is also essentially V-shaped, so that in the area of the base 12 it has a smaller depth, i.e. a smaller distance from the outside of the wall, than in the upper area at the distance 29 at the height of the bending point 20. The dimensions of the bead 31 can be adapted to the gap 22 such that the depth in the base area is approximately 0.1 mm and at the height 29 above the base 12 approximately 0.3 mm. The height 59 of the bead does not have to, but can, correspond to the height 29 of the bending points 10, 20.

However, other dimensions are also possible, so these figures are only examples. In particular, it is possible that the 5 dimensions of the bead are a certain percentage smaller than the dimensions 32 or 33, which define the intended distance between the side walls 15 and 25. In this case, the beads guarantee a minimum distance.

In addition to the embodiment according to Figures 1 to 6, in the embodiment according to Figure 7 in the contact area of the side walls 15 and

·* ·· ·· **·' 26.02.03

G-IP/Gr-16-

25 with the base 12, a recess 30 with a depth 34 of 0.1 mm in the embodiment is provided. The recess 30 facilitates the manufacture of the collecting box 2, since the ends of the side walls 15 and 25 are guided into the recess 30 before soldering, thus providing lateral support.

The beads 31 create large capillary gaps that allow the flux and solder to be distributed well. The beads 31 also serve as a spacer between the outer sides of the middle side walls 15 and 25. This reliably ensures that the distance is not too small to ensure a reliable solder connection.

In the embodiment according to Figures 8 and 9, stability devices designed as grooves 35 are provided. The grooves 35 have a depth 36, which in the embodiment is 0.1 mm. Analogous to the embodiment with the beads 31 according to Figure 7, the depth of the grooves can also change with the distance from the base 12 of the collecting tank in the embodiment with the groove-like depressions 35 according to Figures 8 and 9.

Also in this embodiment, the surface profiling created by the grooves 35 provides stability to the upper part(s) 13 or 23 of the two collecting chambers 3, 4.

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

5 As in the previous embodiment, a recess 30 is provided in the contact area of the middle side walls 15 and 25 and the base 12.

Figure 9 shows a sectional view A-A of Figure 8.

·% . : &iacgr; \ . : &idigr; ·. 03-β-035

.S *,.'%,· %.'· „,· 02/26/03

G-IP/Gr -17-

In Figure 9, the channel-shaped depressions 35 can be seen from above. In this embodiment, the channel-shaped depressions 35 are arranged on both middle side walls 15 and 25.

In this embodiment, the grooves were created by compressing the material during the bending process to produce the mold, so that the depressions shown are created on each of the outer sides of the middle side surfaces.

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

Also in the embodiment according to Figures 8 and 9, the distance 33 in the contact area 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 bending points 10 and 20.

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

The flat tube has external dimensions perpendicular to the flow direction 0 of a coolant of 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 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.

5 The flat tube is divided across its width into a number of 8 flow chambers, the middle 6 having an internal width of 3.2 mm. The partitions 46 have a width 47 of 0.3 mm.

: &ogr;&bgr;&bgr;&idigr;)3

^# 26*02.03

G-IP/Gr-18-

Due to the considerably different wall thicknesses from radius area to flank area, a significantly lower total 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.

Figure 11 shows a side view of a heat exchanger 60, which also comprises collecting boxes 2 and 11.

The collecting boxes 2 and 11 are divided into several longitudinal sections by partition walls 50 and 51, so that a meandering flow path &iacgr;&ogr; of the evaporation medium over the heat exchanger 60 is created.

In this embodiment, the connections 6 and 7 for inlet and outlet are provided on the front sides of the collecting box 2 at the collecting chambers 3 and 4.

With regard to the further design of the heat exchanger and in particular the design and flow conditions of the collecting boxes and the rest of the heat exchanger, reference is made to the applicant's DE 19 82 688 A1 and in particular column 1, line 1, to column 6, line 16 in conjunction with figures 1 to 6, the disclosure content of which is included here.

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

Claims (28)

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 ), wherein essentially each collecting chamber ( 3 , 4 ) is essentially delimited by a base device ( 12 ) and an upper part device ( 13 ), wherein the upper part device ( 13 ) of a first collecting chamber ( 3 ) comprises a first central 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 aid elements are provided at least at locations 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 aid 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 aid elements are introduced by embossing. 4. Heat exchanger according to claim 1, 2 or 3, characterized in that the bending aid 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 aid 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 middle side wall ( 15 ) is arranged adjacent to the second middle side wall ( 25 ) over at least a portion, wherein over at least a portion of a height ( 69 ) of the collecting tank ( 2 ) a lateral distance of the first middle side wall (15) from the second middle side wall ( 25 ) increases with the height above the base device ( 12 ) or remains the same. 7. Heat exchanger according to claim 6, characterized in that the gap ( 22 ) between the first and the second middle side wall ( 15 ; 25 ) is substantially 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 substantially 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. 15. 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 base 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 region 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 region of a flank ( 49 ) than in a region of a radius ( 43 ). 18. Heat exchanger according to claim 17, characterized in that at least one flat tube ( 40 ) in the region of the flanks ( 49 ) has a wall thickness ( 45 ) which is at least 20% smaller than in a region 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 region of the flanks ( 49 ) has a wall thickness of approximately 0.3 mm at least at 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 region 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 manufactured 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 manufactured 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 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 ) of the base device. 27. Heat exchanger according to at least one of the preceding claims, characterized in that a 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 at a front end ( 38 ) of at least one collecting chamber ( 3 , 4 ) of the collecting box ( 2 ).