EP1459027B1 - Heat exchanger, particularly for a motor vehicle - Google Patents

Abstract

The device has pipes carrying a first medium in heat exchange channels between containers and arranged in a flow of a second medium. An end piece contains a collection box with a housing and at least one collection chamber. The housing and a cover plate for at least one through channel have coaxial openings via which the collection chamber(s) communicates with the through channel(s). An independent claim is also included for the following: a coolant heat exchanger, especially for a motor vehicle air conditioning system.

Description

The invention relates to a heat exchanger with pipes and with an end piece, which has a tube plate consisting of plates.

Such a heat exchanger is for example in the EP 0 563 471 A1 described. The local heat exchanger is designed as a double-row flat tube evaporator, which is flowed through in two bends. Between the flat tubes are corrugated fins, which are covered by ambient air. The refrigerant flows through the seen in the main flow direction of the air rear row of flat tubes first from top to bottom and is then collected and deflected by a deflecting counter to the flow direction of the air, enters the first, ie front row of flat tubes and flows through them from bottom to top. In this design, the refrigerant is thus deflected "in the depth", ie counter to the flow direction of the air. As a result, the flow paths for the refrigerant each comprise two sections, each section corresponding to a tube length. The distribution and collection of the refrigerant is carried out by a collecting and distributing device, which is characterized by a plurality of stacked, formed with each other soldered plates. These are essentially a base plate, an overlying distributor plate with a longitudinally extending partition and a cover plate with inlet and outlet opening for the refrigerant. Similarly, the deflector arranged on the opposite side is constructed of individual plates. This results in a low overall height for this evaporator. In addition, optionally a so-called stop plate is provided, which is placed in each case on the bottom plate and forms a stop for the pipe ends. A disadvantage of this evaporator design is that the refrigerant is distributed unevenly on the individual tubes due to the over the entire width of the evaporator extending distribution or collection chamber. In addition, the double-row design requires increased installation costs.

One has for a similar evaporator in the EP 0 634 615 A1 proposed a so-called divider plate with individual openings for the distribution of the refrigerant to the individual tubes. As a result, a more uniform distribution of the refrigerant is achieved on the pipes, but this is achieved by an increased number of plates and thus higher material and assembly costs.

In the US 5,242,016 For example, an evaporator with a refrigerant distribution through channels in a plurality of plates is described, which also contribute to a more uniform distribution of the refrigerant to heat exchanger tubes. For this, however, a very large number of plates and a high production cost is necessary.

By the DE 100 20 763 A1 Another type of evaporator was known, which is intended for operation with CO ₂ as the refrigerant and in which a pressure-resistant collector housing is to be achieved in that a plurality of perforated plates stacked on each other and soldered together. This evaporator is single-row formed, with multi-chamber flat tubes, which are flowed through both upwards and downwards, which is made possible by a deflector located at the lower end of the tube. A disadvantage of this evaporator design is the high number of plates with relatively narrow channels, which means on the one hand additional weight and on the other hand involves the risk that the channels of the collector housing run during soldering, that are clogged by solder.

In the EP 1 221 580 A2 An evaporator for a fuel cell system is described which includes a header having a bottom plate and a cover plate attached thereto. Fuel passes through a connecting part in a fuel distribution chamber, from there into guide channels and through openings in the bottom plate in heat receiving ducts of the evaporator. In this fuel evaporator, the plates of the head are small in number, but very expensive in their production. In addition, the heat receiving channels are acted upon very unevenly with fuel depending on the pressure distribution in the fuel distributor chamber and in the guide channels.

The object of the invention is to provide a heat exchanger in which a simple and / or lightweight construction and optionally at the same time a uniform distribution of a medium to a plurality of flow paths and / or a pressure-stable construction of the heat exchanger can be realized.

This object is achieved by a heat exchanger with the features of claim 1.

According to this claim, a heat exchanger according to the invention has tubes which can be flowed through by a first medium and by a first medium second medium are flowed around, so that by walls of the tubes heat from the first to the second medium or vice versa is transferable. For this purpose, there are heat transfer channels in the tubes, through which the first medium can be conducted, wherein a single tube has either a heat transfer channel or as a so-called multi-chamber tube a plurality of adjacent heat transfer channels. The tubes may have a circular, an oval, a substantially rectangular or any other cross section. For example, the tubes are designed as flat tubes. For an increase in the heat transfer, optionally ribs, in particular corrugated fins, are arranged between the tubes, wherein the tubes and the ribs are in particular solderable to one another.

For the heat exchanger various uses are conceivable, for example as an evaporator of a refrigerant circuit, in particular an automotive air conditioning system. In this case, the first medium is a refrigerant, for example, R134a or R744, and the second medium is air, whereby heat is transferred from the air to the refrigerant. The heat exchanger is also suitable for other media, where appropriate, the heat is also transferable from the first to the second medium.

Optionally, at least two collection chambers are present, wherein the first medium can be conducted from a first to a second collection chamber. The first medium can be conducted along one or more flow paths, which optionally consist of several sections. A flow path section in the sense of the invention is to be understood as meaning one or more heat transfer channels which run from one side of the heat exchanger to an opposite side and are connected hydraulically in parallel to one another. The heat transfer channels of a flow path section are However, for example, arranged in a single tube, an arrangement of the heat transfer channels of a flow path section distributed over several tubes is likewise conceivable.

Furthermore, the heat exchanger has an end piece with a tube plate, which consists of adjacent plates, namely a bottom plate, a baffle plate and a cover plate. The bottom plate is connectable to ends of the tubes by the bottom plate, for example, has recesses into which the pipe ends are receivable. In the context of the invention, other types of connection between pipes and the bottom plate are conceivable, for example, by extensions at the edges of recesses in the bottom plate, so that the tubes are attachable to the extensions. Recesses in the deflection plate serve for the formation of passage channels and / or deflection channels, which can be closed fluid-tight with respect to an environment of the heat exchanger with a cover plate. Due to the plate structure of the tube plate a very pressure-stable construction of the tail and the entire heat exchanger is possible.

A first basic idea of the invention is to provide the end piece comprising the tubesheet with a collection box which has at least one collection chamber for the first medium in a housing. As a result, an optionally necessary anyway component is integrated into the tail and ensures a compact and therefore simple construction of the heat exchanger.

According to a second basic concept of the invention, flow path sections are connected to one another by means of deflection channels in the deflection plate. The interconnection of the flow path sections to one or more hydraulically parallel flow paths is then interpretable according to any requirements, by a single plate, namely the Baffle is configured according to the required flow path interconnection. Thus, the heat exchanger can be built flexibly for various applications due to its modular design.

According to another basic idea of the invention, a tube is introduced into the tubesheet up to a predetermined stop in order to achieve increased manufacturing reliability and thus simplified production. The stop is realized by a web between two recesses in the bottom plate, which is receivable in a recess in a pipe end, wherein the web is substantially as wide as the recess in the pipe end. Advantageously, the recess is slightly wider than the web to facilitate insertion of the tube into the bottom plate. The insertion depth of the tube is given by the height of the recess in the pipe end. Particularly advantageously, the recess is higher than the web, whereby the risk of unwanted clogging of one or more heat transfer channels is reduced by solder located on the bottom plate during a soldering process. The height difference is, for example, 1 mm or more, on the other hand, should be less than the thickness of the baffle, since the pipe otherwise abuts the cover plate. Advantageously, a height difference that is about half as large as the thickness of the baffle plate.

Another basic idea of the invention is to design a plurality of plates of the tubesheet in one piece in order to reduce the number of production and, if necessary, the cost of materials. Under certain circumstances, the tube plate then only consists of a plate in which the bottom plate, the baffle plate and the cover plate are integrated.

According to a further concept of the invention, the cost of materials for the tube plate and thus also for the heat exchanger is reduced by one or more, preferably all plates of the tubesheet additional Have recesses between passage and / or deflection channels, which are formed for example as openings or lateral indentations. Advantageously, the plates are severed between passage and / or deflection channels, whereby the plates may disintegrate into many small sub-plates. This allows a particularly lightweight construction, which has a positive effect on material costs and weight of the heat exchanger alike.

A simplified construction is made possible according to a further basic idea of the invention by U-shaped tubes, wherein the tubes are simply or repeatedly formed into an even simpler construction. As a result, in the region of the U-shaped deformation, two pipe-floor connections and optionally a deflection channel are saved. With the exclusive use of U-tubes, it is even possible to save an end piece, if on one side of the heat exchanger all deflections are realized by Rohrumformungen. In this case, the ends of each tube are connectable to the same bottom plate.

Another idea of the invention is to provide the heat exchanger with exactly one end piece, in which in particular a collecting box is integrated with two collecting chambers. This is possible except through the use of U-tubes through any conceivable hydraulic connection of pipes on a side opposite exactly one end of the heat exchanger, for example by placing suitably constructed caps on a plurality of, in particular two tubes.

Preferred embodiments of the heat exchanger according to the invention are the subject of the subordinate claims.

According to a preferred embodiment, an optionally integrated into the tail collecting tank with the cover plate is fluid-tight soldered or welded. According to another advantageous embodiment of the collecting box is integrally formed with the cover plate, whereby the production is simplified. A particularly lightweight design is achieved by a tubular design of the collecting tank according to a further embodiment of the invention. Particularly preferably, the cover plate on edges of openings on extensions which engage in openings of a housing of the collecting tank. Conversely, it is possible according to a further embodiment, to provide openings of the collection box housing with extensions which engage in openings of the cover plate. In both cases, the manufacturing safety is increased by an alignment of the mutually aligned openings in the cover plate and in the collection box housing.

According to a preferred embodiment, the passage openings, which are formed by the mutually aligned openings in the cover plate and in the collection box housing, have different flow cross-sections. As a result, an adaptation of the distribution of the first medium to the flow conditions in the associated collection chamber is made possible in a simple manner. In particular, a uniform distribution over a plurality of flow paths is desirable, but also a deliberately uneven distribution is conceivable, for example, at uneven mass flow of the second medium over an end face of the heat exchanger. Advantageously, the passage openings are arranged with different flow cross-sections upstream of the heat transfer channels, whereby the flow in the flow paths is particularly easily compensated. If throughflows are regulated by the flow paths on an inlet side for the first medium, the passage openings on the outlet side can be made larger, for example, with a flow cross section which corresponds to the flow cross section of the respective flow path. If the heat exchanger is used, for example, as an evaporator in a refrigerant circuit, the pressure conditions along the circuit are more advantageous for the performance of the heat exchanger, if flow cross sections are narrowed before heating the refrigerant, as in a narrowing of the flow cross sections after heating.

The flow cross-sections of the passage openings are adaptable according to an embodiment of a pressure distribution of the first medium within the respective collection chamber. In another embodiment, the flow cross sections can be adapted to a density distribution of the first medium within the respective collection chamber. For the purposes of the invention, the density of a medium is to be understood as the physical density in single-phase media, while in the case of multiphase media, for example in media which are partly liquid and partly gaseous, a density averaged over the volume in question is to be understood.

For similar reasons, the cross sectional areas of the first and second plenums are different from one another in a preferred embodiment. Particularly preferably, the cross-sectional areas of the collecting chambers can be adapted to the density ratios of the first medium in the chambers.

Further embodiments of the heat exchanger according to the invention relate to the interconnection of the flow path sections by means of deflection channels in the deflection plate.

According to an advantageous embodiment, flow path sections are connected to each other by a deflection channel, which are arranged side by side in the main flow direction of the second medium. One speaks then of a deflection in the width. This makes it possible to connect several or possibly all flow path sections within a row or within a row of pipes together to form a flow path. This leads to an at least partial serpentine construction of the heat exchanger. In another embodiment, the interconnected flow path sections are aligned in the main flow direction of the second medium. One speaks then of a deflection in the depth. This makes it possible to connect flow paths for the first medium parallel or antiparallel to the main flow direction of the second medium. This leads to an at least partial countercurrent construction of the heat exchanger.

According to a further embodiment, two flow path sections are interconnected within a tube by a deflection channel. This means that the first medium flows in one direction through the tube and flows back in the opposite direction through the same tube. By using pipes with many heat transfer channels so the total number of tubes and thus the manufacturing cost is reduced.

According to a preferred embodiment, the number of sections of at least one flow path is divisible by two. This means that a two-row arrangement of the flow path sections is easily interconnected by the first half of the sections of a flow path arranged in a first row and connected by deflections in the width, whereas the second half of the sections arranged in a second row and also through Deflections in width are interconnected, with the two Halves of the flow path are connected by a deflection in depth. This deflection in depth is done for example in a deflection of a baffle plate of a tube plate on the side opposite the collecting chambers of the heat exchanger. Particularly preferably, the number of sections of the flow path is divisible by four. This means that in a double-row arrangement of the flow path sections with the above-described interconnection, the deflection takes place in the depth on the side of the heat exchanger on which the collection chambers are located. As a result, only one baffle of the heat exchanger is to be configured when the heat exchanger is designed for given requirements, while other components are taken over unchanged.

In one embodiment, the first and last flow path sections within one or more rows of tubes are not acted upon as hydraulically first sections of flow paths, since in the edge region of collection chambers, which are usually arranged along rows of tubes, the flow and / or pressure conditions of the first medium are unfavorable for loading of flow paths are.

According to an advantageous embodiment, two adjacent flow paths are mirror-symmetrical to each other. Particularly preferably, deflection channels communicate at least two flow paths. As a result, an additional compensation of the flow is effected within the flow paths. In the case of a mirror-symmetrical course of the flow paths communicating with one another, it is particularly easy to communicate the optionally adjacent deflection channels, for example by omitting a web which may otherwise be present between two deflection channels.

In a further preferred embodiment, a flow cross section of a flow path changes during its course. This is very easy to realize, for example, by connecting flow path sections with few heat transfer channels via correspondingly configured deflection channels with flow path sections with many heat transfer channels. An adaptation of the flow cross section of a flow path to a density of the first medium changing along the flow path is particularly preferred.

An embodiment is advantageous in which all sections of at least one flow path in the main flow direction of the second medium are aligned with one another. Particularly advantageously, all flow paths of the heat exchanger are formed in this manner, whereby a pure countercurrent construction of the heat exchanger in a simple manner, namely by appropriately configured deflection channels in a baffle is possible.

The heat exchanger may consist of flat tubes, which are flowed through by a liquid and / or vapor refrigerant, arranged between the flat tubes, acted upon by ambient air corrugated fins, a collecting and distributing device for the supply and discharge of the refrigerant, wherein the collecting and distributing device a plurality of stacked, perforated plates, whereby refrigerant channels are formed, wherein the ends of the flat tubes are held in receiving openings of a bottom plate and a deflector for deflecting the refrigerant in the direction of flow of ambient air, and wherein the heat exchanger consists of a series of flat tubes, wherein in each case a flat tube two parallel flow sections, which flows through one after the other and over the Deflection device are connected, wherein each flat tube end has a groove between the two flow sections in the middle of the flat tube end and that the bottom plate between the receiving openings webs, which correspond in their dimensions in height and width of the grooves and with the grooves each have a joint connection form.

The deflection can be formed by a further base plate with receiving openings and webs, which form a joint connection with the end-side groove of the flat tubes.

The deflection device may additionally have a channel plate with through slots and a closed cover plate.

The collecting and distributing means may include a channel plate having channel openings and lands between the channel openings, a cover plate having refrigerant entrance and exit openings and a refrigerant supply and a refrigerant discharge channel, which are arranged parallel to each other and in the longitudinal direction of the heat exchanger, wherein the bottom plate, the channel plate and the cover plate are arranged one above the other in such a way that the openings in the plates are aligned with the flat tube ends.

The refrigerant inlet openings may be formed as calibrated bores, wherein the diameter of the bores is in particular variable. Also preferably, the cover plate and the refrigerant supply and -abfuhrkanäle are integrally formed.

The heat exchanger, which can be used in particular as an evaporator for motor vehicle air conditioners is, may consist of flat tubes, which are flowed through by a liquid and / or vapor refrigerant, arranged between the flat tubes, acted upon by ambient air corrugated fins, a collecting and distributing device for the supply and the discharge of the refrigerant, wherein the collecting and distributing device a plurality of stacked, perforated plates, whereby refrigerant channels are formed, wherein the ends of the flat tubes are held in receiving openings of a bottom plate, and a deflection device for deflecting the refrigerant in the flow direction of the ambient air. The heat exchanger consists of a series of flat tubes, wherein in each case a flat tube two parallel flow sections, which are successively flowed through and connected via the deflection, and wherein the collecting and distributing device has a between refrigerant inlet and outlet arranged calibration device, which serves as a cover plate is formed with calibration openings for the refrigerant distribution. Preferably, the calibration openings are arranged on the refrigerant inlet side.

The calibration can have different flow cross sections. The flow cross sections of the calibration openings are preferably larger in the direction of the pressure drop of the refrigerant in the feed channel. Particularly preferably, the flow cross sections of the calibration openings are variable depending on the specific volume of the refrigerant or its vapor content.

The flat tubes can be designed as serpentine segments and the deflection device can be arranged in the collecting and distributing device.

The collecting and distributing device can be a channel plate with continuous channel openings for Deflection of the refrigerant and channel openings with webs, a cover plate with refrigerant inlet and outlet openings and a refrigerant supply and a refrigerant discharge channel have. The channel openings with webs are in each case arranged in alignment with the first flat tube end of the serpentine segment, whereas the through channel openings are arranged in alignment with the second flat tube end of the serpentine segment, wherein the refrigerant inlet and outlet openings are aligned with the channel openings and the continuous channel openings are covered by the cover plate , Preferably, the serpentine segments have two or three deflections in width.

The flat tubes can be designed as U-tubes, that is, each with a deflection (in width). Two U-tubes are particularly preferably connected in series on the refrigerant side, and two adjacent channel openings, which are assigned to a U-tube outlet and a U-tube inlet, are in refrigerant communication with each other through a transverse channel in the channel plate.

Preferably, the width b of the channel openings in the channel plate is greater than the width a of the receiving openings in the bottom plate. Also advantageously, the depth of the groove in the flat tube ends is greater than the thickness of the bottom plate.

Advantageously, one or more of the following dimensions apply to the heat exchanger: Width: 200 to 360 mm, in particular. 260 to 315 mm Height: 180 to 280 mm, in particular. 200 to 250 mm Depth: 30 to 80 mm, preferably 35 to 65 mm Volume: 0.003 to 0.006 m3, in particular. 0.0046 m3 Number of tubes per refrigerant path: 1 to 8, preferably 2 to 4 Diameter of the heat transfer channels: 0.6 to 2 mm, in particular 1 to 1.4 mm Center distance of the heat transfer channels in the depth direction: 1 to 5 mm, preferably 2 mm Transverse division: 6 to 12 mm, in particular 10 mm Tube height: 1 to 2.5 mm, in particular 1.4 to 1.8 mm End face SF in the main flow direction of the second medium: 0.04 to 0.1 m ² , esp. 0.045 to 0.07 m ² Free flow cross section BF for the second medium: 0.03 to 0.06 m ² , in particular 0.053 m ² Ratio BF / SF: 0.5 to 0.9, especially 0.75 Heat transfer surface: 3 to 8 m ² , in particular 4 to 6 m ² Lamella density in corrugated ribs: 400 to 1000 m ^-1 , in particular 650 m ^-1 Channel height: 4 to 10 mm, in particular 6 to 8 mm Slats slot length: 4 to 10 mm, in particular 6.6 mm Slats slot height: 0.2 to 0.4 mm, in particular 0.26 mm Thickness of the bottom plate: 1 to 3 mm, especially 1.5 or 2 or 2.5 mm Thickness of the baffle plate: 2.5 to 6 mm, especially 3 or 3.5 or 4 mm Thickness of the cover plate: 1 to 3 mm, especially 1.5 or 2 or 2.5 mm Collecting box diameter: 4 to 10 mm, in particular 6 to 8 mm Housing wall thickness of a collecting tank: 1 to 3 mm, in particular 1.5 to 2 mm

Fig. 1

einen Parallelstromverdampfer in Explosivdarstellung,

Fig. 2

einen Verdampfer mit Serpentinensegment (Umlenkung in der Breite),

Fig. 3

einen Verdampfer mit U-Rohren,

Fig. 4

einen Schnitt IV-IV durch Verdampfer gemäß Fig. 3,

Fig. 5

einen Schnitt V-V durch Verdampfer gemäß Fig. 3,

Fig. 6

einen Verdampfer mit hintereinandergeschalteten U-Rohren (Umlenkung in der Breite),

Fig. 7

einen Wärmeübertrager in Querschnittsdarstellung,

Fig. 8

einen Wärmeübertrager in einer Teilansicht,

Fig. 9

einen Wärmeübertrager in einer Teilansicht,

Fig. 10

eine Umlenkplatte,

Fig. 11

einen Rohrboden in einer Teilansicht,

Fig. 12

einen Rohrboden in Explosivdarstellung,

Fig. 13

einen Rohrboden in Querschnittsdarstellung,

Fig. 14

einen Rohrboden in Längsschnittsdarstellung,

Fig. 15

einen Rohrboden,

Fig. 16

einen Rohrboden in Querschnittsdarstellung,

Fig. 17

einen Wärmeübertrager in einer Teilansicht,

Fig. 18

einen Rohrboden in Querschnittsdarstellung,

Fig. 19

einen Rohrboden,

Fig. 20

einen Rohrboden,

Fig. 21

einen Rohrboden,

Fig. 22

einen Rohrboden,

Fig. 23

einen Rohrboden,

Fig. 24

einen Wärmeübertrager in einer Teilansicht und

Fig. 25

einen Rohrboden in einer Teilansicht.

The invention will be explained in more detail by means of embodiments with reference to the drawings. Show it:

Fig. 1

a parallel flow evaporator in explosive representation,

Fig. 2

an evaporator with serpentine segment (deflection in the width),

Fig. 3

an evaporator with U-tubes,

Fig. 4

a section IV-IV by evaporator according to Fig. 3 .

Fig. 5

a section VV by evaporator according to Fig. 3 .

Fig. 6

an evaporator with U-tubes connected in series (deflection in the width),

Fig. 7

a heat exchanger in cross-sectional view,

Fig. 8

a heat exchanger in a partial view,

Fig. 9

a heat exchanger in a partial view,

Fig. 10

a baffle,

Fig. 11

a tube plate in a partial view,

Fig. 12

a tube sheet in an exploded view,

Fig. 13

a tube plate in cross-sectional view,

Fig. 14

a tube plate in longitudinal section,

Fig. 15

a tube sheet,

Fig. 16

a tube plate in cross-sectional view,

Fig. 17

a heat exchanger in a partial view,

Fig. 18

a tube plate in cross-sectional view,

Fig. 19

a tube sheet,

Fig. 20

a tube sheet,

Fig. 21

a tube sheet,

Fig. 22

a tube sheet,

Fig. 23

a tube sheet,

Fig. 24

a heat exchanger in a partial view and

Fig. 25

a tube sheet in a partial view.

Fig. 1 shows as the first embodiment, an evaporator for an operated with CO ₂ as a refrigerant automotive air conditioning system, in an exploded view. This evaporator 1 is designed as a single-row flat tube evaporator and has a plurality of flat tubes, of which only two flat tubes 2, 3 are shown. These flat tubes 2, 3 are formed as extruded multi-chamber flat tubes, which have a plurality of flow channels 4. All flat tubes 2, 3 have the same length I and the same depth t. At each tube end 2a, 2b, a groove 5, 6 symmetrical to the central axis 2c in the flat tube 2 is incorporated. Between the individual flat tubes 2, 3 are corrugated fins 7, which are acted upon by ambient air in the direction of the arrow L. The corrugated fins 7 are continuous in the depth direction, but can also be interrupted, for example, in the middle of the depth t, to ensure a better condensate drain and / or thermal separation.

In the drawing above the flat tubes 2, 3, a bottom plate 8 is shown, in which a first row of slot-shaped openings 9a - 9f and a second row of just such openings 10a - 10f are arranged. The openings 9a and 10a, 9b and 10b, etc. lie in the direction of the depth (air flow direction L) one behind the other and leave between each webs 11a, 11b - 11 f. With regard to their width in the depth direction, these webs 11a-11f correspond to the width of the cutout 5 of the pipe ends 2a. The number of openings 9a-9f or 10a-10f corresponds to the number of flat tubes 2, 3.

In the drawing above the bottom plate 8, a so-called baffle 12 is shown, in which two rows of openings 13a - 13f and 14a - 14f (partially hidden) are arranged. The arrangement of the apertures 13a-f and 14a-f corresponds to the arrangement of the apertures 9a-9f or 10a-10f, but the apertures 13a-f and 14a-f are larger in their width b and depth than the corresponding dimensions of the apertures 9a - 9f or 10a - 10f, each having only a width of a, which corresponds to the thickness of the flat tubes 2, 3. Between the openings 13a, 14a, 13b, 14b - 13f u. 14f are each webs 15a - 15f left. With regard to their dimensions in the depth direction, these webs 15a-15f are smaller than the corresponding dimensions of the webs 11a-11f of the bottom plate 8.

In the drawing above the baffle 12, a so-called cover plate 16 is shown, which has a first row of refrigerant inlet openings 17a-17f and a second row of refrigerant outlet openings 18a-18f. These openings 17a - 17f u. 18a-18f are preferably formed as circular bores and adapted in terms of their diameter to the desired refrigerant distribution or flow rate.

Finally, in the drawing above the cover plate 16, a collecting box 19 with a housing and in each case a collecting chamber 20, 21 for the supply and the discharge of the refrigerant. The collection box has openings 22a-f and 23a-f for both collection chambers on its underside, shown in dashed lines, which correspond in terms of position and size to the openings 17a-f and 18a-f.

In the drawing below the flat tubes 2, 3, a further bottom plate 24 is shown, which has two rows of slot-shaped openings 25a-f and 26a-f analogous to the first bottom plate 8. Also located between the apertures 25a and 26a to 25f and 26f are webs 27a-f (partially concealed), these webs, with respect to their width in the depth direction, corresponding to the width of the recess 6 in the end of the flat tube 2. In the drawing below the second bottom plate 24, a further baffle plate 28 is shown, the continuous deflection channels 29a - 29f has. These deflection channels 29a-f extend over the entire depth t of the flat tubes 2, 3.

Finally, in the drawing below, a cover plate 30 is shown which has no openings, but closes the deflection channels 29a-29f with respect to the surroundings of the heat exchanger.

The above-described constituent parts of the evaporator 1 are mounted as follows: On the flat tube ends 2a, etc., the bottom plate 8 is placed, so that the webs 11a - 11f come to lie in the recesses 5 of the flat tube ends. About the bottom plate 8 then the baffle 12, the cover plate 16 and the collection box 19 with the collection chambers 20, 21 are stacked. In an analogous manner, the lower bottom plate 24 is on the Flat tube ends 2b pushed so that the webs 27a - 27f come to lie in the recesses 6; Thereafter, the channel plate 28 and the cover plate 29 are added. After the evaporator 1 is thus joined together, it is soldered in a soldering furnace to form a solid block. During the soldering process, the plates are held by a positive or non-positive tension in their position to each other. But it is also possible to first mount the tail of base plate, baffle and cover plate and then connect with flat tubes.

The course of the refrigerant flow is shown by way of example with reference to a series of arrows V1-V5 on the front side of the evaporator, through the deflection arrow U in the deflection channel 29c and the arrows R1, R2 and R3 on the rear side of the evaporator 1. The refrigerant, in this case CO ₂ , thus flows through the evaporator initially on the front side from top to bottom, specifically in the front section 2 d of the flat tube 2, in the lower, consisting of the plates 24, 28, 30 tube plate in depth deflected and flows on the back of the evaporator 1, ie in the rear flow section 2e of the flat tube 2 from bottom to top, corresponding to the arrows R1, R2 and R3 to the collection chamber 21st

Fig. 2 shows a further embodiment of the invention, namely an evaporator 40, in which the aforementioned flat tubes are formed as serpentine segments 41. Such a serpentine segment 41 consists of four flat tube legs 42, 43, 44 u. 45, which are interconnected by three Umlenkbögen 46, 47, 48. Between the individual Flachrohrschenkeln 42 - 45 corrugated fins 49 are arranged. The other parts of the evaporator are also shown in an exploded view, ie a bottom plate 50, a baffle 51, a cover plate 52 and collecting chambers 53, 54 for a refrigerant supply or removal. The bottom plate 50 has a front row of slit-shaped openings 55a, 55b u. 55c, behind which there is a second row (partially hidden) of corresponding openings. Between two rows of openings in turn webs 56a, 56b u. Leave 56c, with recesses 57 u. 58 in the ends 42a u. 45a of the serpentine segment 41 correspond. These flat tube ends are thus inserted through the openings in the bottom plate, wherein the webs come to lie in the recesses. Above the bottom plate 50 follows the baffle 51, which has a aligned with the opening 55a of the bottom plate 50 opening 59a. In the depth direction behind the opening 59a is located (partially hidden) a corresponding opening, which is separated by a ridge 60a of the opening 59a. This web 60a is in turn smaller than the recess 58 of the flat tube leg 42. Adjacent to the opening 59a and at a distance corresponding to that of the flat tube ends 42a-45a, a deflection channel 61 is arranged which extends over the entire depth of the flat tube leg 45. Adjacent to the deflection channel 61 then follows an opening 59b, which corresponds in size to the opening 59a. It corresponds to the next Flachrohrserpentinensegment, which is not shown here. Above the baffle 51 is the cover plate 52, in the front row two refrigerant supply openings 62, 63 and in the rear row two refrigerant outlets 64 u. 65 has. The latter correspond in terms of size and location with the dashed lines in the collection chambers 53, 54 openings (without reference number).

The refrigerant flow path is illustrated by arrows: First, the refrigerant leaves the collection chamber 53 via the arrow E1, then follows the arrows E2, E3, E4 and enters the front flow section of the flat tube leg 42 and flows through the entire serpentine segment 41 on its front side and enters E6 from the last leg 45, enters the deflection channel 61, where it is deflected in the depth according to the arrow U, and then, following the arrow R1, to flow through the back of the serpentine segment, ie in the opposite direction, as on the front. Finally, this refrigerant flow passes via the arrow R2, ie through the opening 64 into the collecting chamber 54.

By this construction, therefore, a deflection of the refrigerant in the width of the evaporator, i. scored transversely to the main flow direction of the air, first in the drawing from right to left on the front, and then from left to right on the back. As already mentioned above, one or more serpentine segment sections (not shown) adjoin the serpentine segment section 41 shown in the drawing.

In Fig. 2 only one serpentine segment section 41 arranged on the right is shown. Contrary to the above description, the next following this serpentine segment portion 41 can also be traversed in the opposite direction in the width, ie in the drawing from left to right or from outside to inside. In view of the end face of the evaporator, this would therefore flow symmetrically from the outside to the inside on the front side; in the middle, both refrigerant flows - combined in a common deflection channel, which then functions as a mixing chamber - can be deflected in depth and again on the rear side flow from the inside to the outside.

Fig. 3 shows a further embodiment of the invention, namely an evaporator 70, the flat tubes of individual U-tubes 71 a, 71 b, 71 c, etc. are formed. It is thus a serpentine segment section with a deflection and two legs 72 u. 73. The not visible in the drawing ends of the flat tube legs 72 u. 73 are analogously, ie as described above, fixed in a bottom plate 74 with corresponding receptacles. Arranged above the base plate 74 is a deflection plate 75, which alternately has two slit-shaped openings 76, 77 lying one behind the other in the depth direction, leaving a web 78 and a deflecting channel 79 extending in the depth direction. The cover plate - analogous to the embodiments described above - is omitted in this illustration.

The flow of the refrigerant is according to the arrows, i. the refrigerant enters at E in the front flow section of the U-tube 71 a, initially flows down, is deflected down, then flows upwards and enters the deflection channel 79, where it is deflected according to the arrow U, then flows on the Back down, is deflected there and then flows back up to pass through the arrow A through the opening 77. The supply and discharge of the refrigerant will be described with reference to the following figure, corresponding to the sections IV - IV and V - V.

Fig. 4 shows a section along the line IV - IV through the evaporator according to Fig. 3 in an enlarged view and supplemented by a cover plate 80 and a collection box 81 and a collection box 82. The remaining parts are denoted by the same reference numerals as in Fig. 3 referred to, ie the baffle 75, the bottom plate 74 and the flat tube leg 71c. The baffle 75 has two apertures 76c and 77c which are separated by the web 78c. In the cover plate 80, a refrigerant inlet opening 83 is provided, which is arranged with an aligned refrigerant opening 84 in the collecting box 81. Similarly, on the side of the header tank 82, a refrigerant discharge opening 85 in the cover plate 80 and an aligned refrigerant opening 86 in the header box 82 are provided arranged. The collection boxes 81, 82 are sealed and pressure-tight soldered to the cover plate 80, as well as the other parts 80, 75, 74 and 71 c.

Fig. 5 shows a further section along the line V - V in Fig. 3 , ie through the deflection channel 79d. Like parts are again denoted by the same reference numerals. It can be seen that the refrigerant, represented by the arrows, is deflected in the left flat tube section from bottom to top flowing in the deflection channel 79d to the right and in the right or rear portion of the flat tube leg 71 c passes to flow there from top to bottom ,

This construction of the evaporator according to Fig. 3 . 4 and 5 with simple U-tubes therefore allows a simple deflection in width and depth.

Fig. 6 shows as a further embodiment of the invention, an evaporator 90, which in turn is constructed of U-tubes 91 a, 91 b, 91 c, etc. The ends of the U-tube legs are again - which is not shown in the drawing - received in a bottom plate 92, over which a baffle plate 93 is located. The baffle plate 93 has a configuration of openings, in which in each case after two U-tubes, so z. B. 91 a and 91 b, repeated a pattern. In the following, this pattern is described, beginning in the drawing at the top left: There are two successively arranged in the depth direction openings 94 and 95, in the width direction close the openings 96 and 97 and 98 and 99, wherein the openings 96 and 98th in the width direction via a transverse channel 101 and the apertures 97 and 99 via a transverse channel 100 are in refrigerant communication, so that there are two H-shaped openings. The H-shaped openings adjacent a continuous deflection channel 102 is arranged. Thereafter, the pattern of breakthroughs 94 just described is repeated. 102. Through this configuration of breakthroughs, it is possible to connect two U-shaped refrigerant pipes on the refrigerant side one behind the other, so here the U-tubes 91 a and 91 b. The refrigerant flow is represented by arrows: The refrigerant enters at A in the front part of the left leg of the U-tube 91 a and flows down, is deflected, flows back up and is in the baffle 93 via the transverse channel 101, ie following the arrow B in the next U-tube 91 b deflected. There it flows down, is deflected, flows back up and enters the deflection channel 102, where it, following the arrow C, deflected in depth and then flows through the rear part of the two flat tube legs 91b and 91a, to finally at D again withdraw. The cover plate and the refrigerant supply and removal and here for a better representation of the refrigerant flow omitted. By this series connection of two U-tubes on the one hand, a triple deflection in the width is possible, on the other hand, each U-tube leg is received in the bottom plate, so that there is a pressure-stable design. Of course, according to this pattern, a four- or multiple deflection in width can be realized, for which only U-shaped flat tubes are needed. The upper deflection thus takes place in each case in the channel plate 93.

In Fig. 1 are collection chambers 20 and 21 and in Fig. 4 Collecting boxes 81 and 82 for the supply and discharge of refrigerant shown. According to one embodiment of the invention, it is possible, in particular on the respective refrigerant inlet side, a distribution device according to the DE 33 11 579 A1 , ie a coiled profile body, or according to the DE 31 36 374 A1 the applicant, a so-called slide body, use, so that a uniform refrigerant distribution and thus a uniform temperature distribution is achieved at the evaporator. It may be advantageous if in each case several, for example, four adjacent refrigerant inlet openings supplied via a common chamber become; This makes it possible that in a profile body with, for example, five channels four times five equal to 20 refrigerant inlet breakthroughs can be supplied with refrigerant. For this purpose, the (initially) axially parallel extending (five) channels are each coiled behind a group of refrigerant inlet openings (by about 72 °), so that the adjacent chamber comes into connection with the next group of refrigerant inlet openings.

Fig. 7 shows a cross section of a heat exchanger 110 with an end piece 120, which has a bottom plate 130, a baffle 140, a cover plate 150 and manifolds 160, 170. A tube 180 is received in two openings 190, 200 in the bottom plate 130, wherein a recess 210 in one end of the tube 180 rests against a web 220 of the bottom plate 130. The recess 210 is slightly higher than the web 220, so that the pipe end protrudes slightly beyond the bottom plate 130. Heat transfer channels (not shown) in the pipe 180 communicate with passages 230, 240 in the baffle plate 140. The passages 230, 240 are again via recesses 250, 260 in the cover plate 150 and recesses 270, 280 in the housings 290, 300 of the headers 160, 170 connected to collection chambers 310, 320. For improved manufacturing safety, the edges of the recesses 250, 260 are provided with extensions 330, 340, which engage in the recesses 270, 280, whereby an orientation of the headers 160, 170 with respect to the cover plate 150 is accomplished such that the recesses 250th or 260 in the cover plate 150 with the recesses 270 and 280 in the collection box housings 290, 300 are aligned.

Fig. 8 shows a development of the heat exchanger Fig. 6 , The configuration of deflection channels also has a pattern in the heat exchanger 410, which repeats after every two U-tubes 420, and that a flow path through the heat exchanger 410 equivalent. Here, however, two adjacent flow paths are arranged mirror-symmetrically to each other. This means that either the passageways 430, 440 of a flow path 450 next to the passageways 460, 470 of an adjacent flow path 480 or a deflection channel 490 of a flow path 500 next to a deflection channel 510 of an adjacent flow path 520 comes to rest. In the latter case, it is possible to connect the adjacent deflection channels 530, 540 with a connecting channel 545, so that a mixture and a flow compensation between the flow paths involved 550, 560 is realized. This is particularly effective in a region of the edge of the heat exchanger, since there, where appropriate, the flow conditions are otherwise particularly unfavorable for the performance of a heat exchanger. In other areas of the heat exchanger, a mixture of the first medium by means of a connecting channel between two adjacent deflection channels is also possible. The flow paths 450, 480, 485, 500, 520, 550, 560 each consist of eight sections, whereas the flow path 445 consists of only four sections to reduce a pressure drop along the flow path 445, also due to the unfavorable flow conditions in the peripheral areas of one heat exchanger. In this case, mixing with the adjacent flow path 450 is also appropriate.

Fig. 9 11 shows another example of a connection pattern of flow path sections of a heat exchanger 610. Here, the flow path sections 620 on the inlet side 630 of the heat exchanger 610 have a smaller flow cross section than the flow path sections 640 on the exit side 650. For example, if the heat exchanger 610 is used as an evaporator, this asymmetry serves for a Adapting the flow cross-sections to the density of the first medium along the flow paths 660.

Fig. 10 shows another example of a wiring pattern of flow path portions of a heat exchanger 710, accomplished by a configuration of passage and Umlenkkanälen a baffle 720. Here, the flow paths 730 and 740 are respectively aligned so that an inlet and an outlet of the first medium, given by passages 750, 760 and 770, 780, as far as possible from edges 790 and 800 of the heat exchanger 710 are arranged.

Fig. 11 FIG. 12 shows another example of a wiring pattern of flow path portions of a heat exchanger 810 accomplished by a configuration of the bypass and bypass passages 812, 814 of a baffle 820. Here, the flow path sections are in the order 1 (down) - 2 (up) - 3 (down) - 4 (up) - 5 (down) - 6 (up) etc. interconnected with each other.

Fig. 12 shows a tube sheet 1010 with a cover plate 1020 and a plate 1030, which is formed by a one-piece design of a baffle plate with a bottom plate. The cover plate 1020 has recesses 1040 for connection to two collection chambers, while in the plate 1030 passageways 1050 of the baffle plate and below it narrower tube receptacles 1060 can be seen in the bottom plate.

FIGS. 13 and 14 show the tubesheet Fig. 12 in a cross section or in a longitudinal section, in each case in the installed state with a tube 1070th

Fig. 15 shows a similar tube sheet 1110, the cover plate 1120 has no recesses. In the baffle and the bottom plate comprehensive deflection plate 1130 deflection channels 1140 are arranged for a deflection in depth.

Fig. 16 shows a further possibility of the embodiment of a two-part tube sheet 1210. Here, the baffle plate is integrally formed with the cover plate, whereby a plate 1220 is formed. The plate has a deflection channel 1230 for a deflection in the depth, which is given by a curvature. The bottom plate 1240 is also curved, so that the 1260 received in the recess 1250 of the bottom plate 1240 tube 1260 is held firm and thus more pressure stable. The tube 1260 abuts the edge 1270, 1280 of the Umlenkkanals 1230, since the curvature in the plate 1220 is not as wide as the curvature in the plate 1240th

Fig. 17 shows a heat exchanger 1310 in pure countercurrent construction. The pure countercurrent design is characterized in that deflections take place only in depth, but not in width. It does not matter from how many sections the flow paths exist. The flow paths may for example consist of four sections, in each case then three deflections in depth are necessary. The heat exchanger 1310 has flow paths 1320, each with a deflection in the depth and thus with two flow path sections, which are aligned with each other in the main flow direction of the second medium on. The upper end piece 1330 has a tube plate 1340 and two collection boxes not shown for clarity. The tube plate consists of a bottom plate 1350, a baffle 1360, which serves in this case only a passage of the first medium, and a cover plate 1370 with openings 1380 for connection to the collecting boxes. The lower end piece 1390 consists of only one plate 1400, in which a bottom plate, a baffle plate and a cover plate is integrated. The construction of the plate 1400 will be described with reference to the following FIGS. 18 and 19 explained.

Fig. 18 shows a cross section and Fig. 19 a broken oblique view of the plate 1400 from Fig. 17 , A tube 1410 is received in a recess 1420, which also serves as a deflection channel for the first medium, wherein the deflection channel is closed to the outside through the area 1430 of the plate 1400. By a taper, the recess 1420 edges 1440, 1450, which serve the pipe 1410 as a stop. In this way, a one-piece tube sheet is given with a very simple construction and high pressure stability. The tube 1410 serves to represent two sections (downwards 1460 and upwards 1470) of a flow path.

Fig. 20 shows a similarly constructed tube sheet 1800, which is also constructed in one piece and on the Umlenkkanäle 1820 and the pipe stops 1830 addition openings 1810 in the region of the cover plate to be connectable to one or two headers.

In summary, the invention allows a heat exchanger, which consists of a series of tubes (for the realization of heat transfer channels), two plates (the tubesheets) and two tubes (the collection boxes). This is an extremely simple and also pressure-stable construction of the heat exchanger feasible.

The FIGS. 21 to 24 show exemplary embodiments of a tube sheet with little material and thus associated with low material costs and low weight.

The tube sheet 2010 in Fig. 21 has between the pipe receiving recesses 2020 with the pipe stop edges 2030 for material savings as openings 2040 formed recesses. For the same reason, in the tube sheet 2110 in FIG Fig. 22 when lateral indentations 2120 formed recesses provided. The tubesheet 2210 in FIGS. 23 and 24 is completely severed between the 2220 pipe receiving cutouts. In this case, the tubes 2230 may be stabilized only by the corrugated fins 2240.

Fig. 25 FIG. 14 shows another example of a wiring pattern of flow path portions of a heat exchanger 2310 accomplished by a configuration of passage and deflection passages 2320, 2330 of a baffle 2340. Here, the flow path sections are in order 1 (down) - 2 (up) - 3 (down) - 4 (up) - 5 (down) - 6 (up) interconnected. It is possible to provide a tube for each flow path section. However, a tube preferably contains two or more flow path sections, for example the flow path sections 1, 4 and 5 or the flow path sections 2, 3 and 6. In this embodiment, flat tubes are particularly well suited for this purpose. Any further interconnection patterns of flow path sections are also conceivable over the ones shown.

The present invention has been described in part by the example of an evaporator. It is noted, however, that the heat exchanger according to the invention is also suitable for other uses.

Claims (34)

1. Heat exchanger, in particular for a motor vehicle, having tubes (2) through which a first medium can flow in heat-exchange passages and around which a second medium can flow, it being possibly for the first medium to be passed from a first collection chamber (20) to a second collection chamber (21), and having at least one end piece, which comprises a tube plate made up of individual plates bearing against one another, ends of the tubes (2) being connected to a base plate (8) of the tube plate, and at least one through-passage (13a) being formed by a cutout in a diverter plate (12) of the tube plate, which through-passage can be closed off in a fluid-tight manner with respect to an environment surrounding the heat exchanger by means of a cover plate (16), characterized in that the end piece comprises a collection box (19) having a housing and at least one collection chamber (20), the housing and the cover plate (16) having apertures (17a, 22a) which are aligned with one another and through which the at least one collection chamber (20) is in communication with the at least one through-passage (13a).
2. Heat exchanger as claimed in claim 1, characterized in that the collection box (160) is welded or brazed to the cover plate (150).
3. Heat exchanger as claimed in claim 1 or 2, characterized in that the collection box is formed integrally with the cover plate.
4. Heat exchanger as claimed in one of claims 1 to 3, characterized in that the collection box (160) is of tubular design.
5. Heat exchanger as claimed in one of claims 1 to 4, characterized in that the cover plate (150), at edges of apertures (250), has extensions (330) which engage in apertures (270) in the collection box housing (290).
6. Heat exchanger as claimed in one of claims 1 to 5, characterized in that the housing of the collection box, at the edges of apertures, has extensions which engage in apertures in the cover plate.
7. Heat exchanger as claimed in one of claims 1 to 6, characterized in that the through-openings, which are respectively formed by two aligned apertures, have different cross sections of flow.
8. Heat exchanger as claimed in claim 7, characterized in that the through-openings with different cross sections of flow are arranged upstream of the heat-exchange passages.
9. Heat exchanger as claimed in claim 7 or 8, characterized in that the cross sections of flow of the through-openings increase in the direction of a decreasing pressure of the first medium inside the collection chamber in a region of the through-openings while the heat exchanger is operating.
10. Heat exchanger as claimed in one of claims 7 to 9, characterized in that the cross sections of flow of the through-openings increase in the direction of a decreasing density of the first medium within the collection chamber in a region of the through-openings while the heat exchanger is operating.
11. Heat exchanger as claimed in one of claims 1 to 10, characterized in that a cross-sectional area of the first collection chamber is larger or smaller than a cross-sectional area of the second collection chamber.
12. Heat exchanger as claimed in claim 11, characterized in that a ratio of the cross-sectional areas of the collection chambers is approximately equal to the reciprocal of a ratio of the densities of the first medium within the collection chambers while the heat exchanger is operating.
13. Heat exchanger as claimed in one of the preceding claims, characterized in that at least one diverter passage (61), formed by a cutout in the diverter plate (51), connects the heat-exchange passages of two flow-path sections through which the first medium can flow in succession to one another, in particular on the basis of predetermined criteria.
14. Heat exchanger as claimed in claim 13, characterized in that the two flow-path sections which are connected to one another are arranged laterally next to one another in a main direction of flow of the second medium.
15. Heat exchanger as claimed in claim 13, characterized in that the two flow-path sections which are connected to one another are aligned with one another in a main direction of flow of the second medium.
16. Heat exchanger as claimed in one of claims 13 to 15, characterized in that the two flow-path sections which are connected to one another are arranged in a single tube.
17. Heat exchanger as claimed in one of claims 13 to 16, characterized in that the number of sections of at least one flow path can be divided by two, in particular, by four.
18. Heat exchanger as claimed in one of claims 13 to 17, characterized in that for each flow path hydraulically the first section is arranged in a tube which, within a row of tubes, is adjoined by tubes on two opposite sides.
19. Heat exchanger as claimed in one of claims 13 to 18, characterized in that two adjacent flow paths run mirror-symmetrically with respect to one another.
20. Heat exchanger as claimed in one of claims 13 to 19, characterized in that diverter passages of at least two flow paths communicate with one another.
21. Heat exchanger as claimed in one of claims 13 to 20, characterized in that a cross section of flow of a flow path changes from one section to a hydraulically succeeding section.
22. Heat exchanger as claimed in claim 21, characterized in that the cross section of flow of the flow path increases in the direction of a decreasing density of the first medium within the flow path while the heat exchanger is operating.
23. Heat exchanger as claimed in one of claims 13 to 22, characterized in that all sections of at least one flow path are aligned with one another in the main direction of flow of the second medium.
24. Heat exchanger as claimed in one of the preceding claims, characterized in that a tube has a cutout at a tube end and the tube plate has a tube-receiving part with a web, the cutout and the web being of similar width and in particular similar height.
25. Heat exchanger as claimed in claim 24, characterized in that the height of the cutout is greater than that of the web.
26. Heat exchanger as claimed in one of the preceding claims, characterized in that the diverter plate is formed integrally with the base plate and/or with the cover plate.
27. Heat exchanger as claimed in one of the preceding claims, characterized in that the base plate, the diverter plate and/or the cover plate are fully separated in regions between through-passages and/or diverter passages and/or have cutouts in the form of apertures or notches.
28. Heat exchanger as claimed in one of the preceding claims, characterized in that a tube is deformed approximately into a U shape one or more times.
29. Heat exchanger as claimed in claim 28, characterized in that the ends of the at least one deformed tube can be connected to the same base plate.
30. Heat exchanger as claimed in one of the preceding claims, characterized in that the heat exchanger has precisely one end piece with a tube plate comprising individual plates bearing against one another.
31. Heat exchanger as claimed in one of the preceding claims, characterized in that the diverter plate is welded or brazed to the base plate and/or to the cover plate.
32. Heat exchanger as claimed in one of the preceding claims, characterized in that the base plate, the diverter plate and/or the cover plate has, at an edge of at least one aperture, an extension which engages into an aperture in an adjacent plate.
33. Heat exchanger as claimed in one of the preceding claims, characterized in that the tubes are welded or brazed to the base plate.
34. Heat exchanger as claimed in one of the preceding claims, characterized in that the tubes are formed as flat tubes, in particular with corrugated fins between them.

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