EP1376043A2 - Heat exchanger with diffuser - Google Patents

Abstract

Engine cooling fluid flows through the heat exchanger to extract heat from the exhaust gas. The diffuser surrounds the rectangular-section tube (2) through which the exhaust gas flows and the tube has a wall (3) separating the exhaust gas from the cooling fluid. The tube has a lining dividing it into two channels (2a,2b). The channels are in contact along one of their broad sides (15) and contain baffles (26). The lining is supported by the inner surface (5) of the tube and is made of sections pinched together by pinched groove regions (6,7) in the tube.

Description

The invention relates to a heat exchanger with a diffuser to a medium in insert flat heat exchanger tubes, or with a collecting box to one Take up medium from the flat heat exchanger tubes and forward, wherein the diffuser or the collector box has a wall that extends along the ends of a stack of flat heat exchanger tubes and which is tightly connected to the ends by means of soldering.

Such a heat exchanger with a collecting tank is known, for example, from WO 00/75591, but also from a large number of other documents. The wall that extends along the ends of the heat exchanger tubes is undeformed there, i.e. straight through, and the end faces of the flat heat exchanger tubes, which consist of two tube halves, are slit a short distance in the connection area of the tube halves, so as to form a joint, in the wall of the collecting box is used to make the connection by means of soldering. It can be assumed that the tight connection of the wall to the ends of the stack of flat heat exchanger tubes will not be without difficulties, especially since the wall thickness of the heat exchanger tubes is significantly less than 1.0 mm. Furthermore, it does not appear to be provided there that the heat exchanger, which is prefabricated for soldering, can be pre-fixed by means of the collecting box. The prefixing, however, seems to be achievable with the solution from DE 197 22 097 A1, because there the two longitudinal walls of the header tank and the narrow walls of the heat exchanger tubes are deformed in a wave shape so that they correspond to one another. However, in the heat exchanger shown there, it is difficult to realize a tight connection of the wall of the header box at the joint areas between the heat exchanger tubes.
Other documents which show something similar are, for example, EP 775 884 A2 and EP 1 139 052 A2.
Other heat exchangers which have the features of the generic term are the so-called plate heat exchangers without housing. EP 0 992 756 A2 is mentioned in particular for this purpose. The difference between the heat exchangers described above and the housing-free plate heat exchangers is that in the former, corrugated fins or the like are arranged between the flat heat exchanger tubes, through which cooling air often flows freely, while in the plate heat exchangers the heat exchanger tubes are formed by means of deformed heat exchanger plates, so that are stacked together so that heat exchanger tubes for different media are directly adjacent to each other. In the latter document, the ends of the stack of heat exchanger tubes open into a tube sheet. At the edge of the tube sheet, the collecting box or the diffuser is attached all around with its wall.

The object of the invention is to provide a heat exchanger with a To develop a collection box or a diffuser, the wall of which is tightly sealed Ends of a stack of flat heat exchanger tubes and so should be trained to carry out the soldering process prepared stack can fix.

The solutions according to the invention are the subject of claim 1 or Claim 13.

The wall of the header or diffuser extends circumferentially around the entire circumference of the end of the stack of flat heat exchanger tubes and has elevations and / or depressions and / or slots. The ridges and / or slots correspond to protrusions on the periphery of the stack. The depressions correspond to furrows in the circumference of the stack, so that a tight connection between the circumference and the wall of the diffuser is ensured.
The surrounding wall also represents a pre-fixation of the stack because it can hold the entire stack together. The expenditure for auxiliary devices can thus be significantly reduced. The circumferential wall of the diffuser or the collecting box can be pushed so far over the end of the stack of flat heat exchanger tubes that there is a sufficiently large connection area between the wall and the tube ends. Thus, high quality solder connections can be expected.

Each elevation in the wall is a fold, with each fold receiving a protrusion that is the edge flange of the heat exchanger tubes consisting of two flat tube halves.
Each recess in the wall is an internally protruding nose which fills the joint between two heat exchanger tubes, which is a furrow on the circumference of the stack. However, a furrow should also be understood to mean a paragraph in the scope of the stack.

As an alternative to the fold, slots can be provided in the wall that are straight are dimensioned so that they take up a protrusion, the edge flange which is made up of two flat tube halves.

The ends on the broad sides of the flat heat exchanger tubes lie against one another and are connected, the joints (furrows) being the seams on the edge between two heat exchanger tubes.
Alternatively, there may also be a distance between the broad sides at the ends of the flat heat exchanger tubes.
In particular with regard to the pre-fixation, it is also advantageous if the wall of the diffuser or the header tank consists of two narrow walls and two wide walls and the wide walls have extensions which extend to the ends of end plates which cover and reinforce the stack of flat heat exchanger tubes. This training is available when the stack height is smaller than the large diameter of the flat heat exchanger tubes, which is useful in a special application for exhaust gas heat exchangers. Depending on the dimensions of the heat exchanger tubes and the stack height, the extensions could otherwise also be arranged on the narrow walls.
The extensions have a gradation and the end plates have tabs at the ends, which are bent after the preassembly of the heat exchanger in order to lie against the extensions and to hold the heat exchanger together.
A manufacturing advantage is when the diffuser is a part made by deep drawing.
Further features are the subject of the claims.
In particular, reference should be made to claims 13 to 16. Independent claim 13 relates to a heat exchanger that has at least one inlet or outlet in its diffuser. A heat exchanger with such a further developed diffuser allows additional simplifications in terms of manufacture and function. It can also be used with advantages where the restrictions on the installation side do not allow the inlets and outlets for the coolant to be fitted in projections of the flat tube halves.

Fig. 1

Schnitt l - l aus Fig. 3;

Fig. 2

perspektivische Ansicht des Wärmetauschers mit anzusetzenden Diffusoren;

Fig. 3

perspektivische Ansicht des Wärmetauschers mit angesetzten Diffusoren;

Fig. 4 und Fig. 5

Draufsichten auf einen Diffusor;

Fig. 6

perspektivische Ansicht auf einen Diffusor;

Die Fig. 7 bis 15 zeigen eine weitere erfinderische Gestaltung des Wärmetauschers mit einem Diffusor in mehreren perspektivischen Ansichten.
Im Ausführungsbeispiel ist ein aus einem Plattenstapel bestehender gehäuseloser Wärmetauscher gezeigt, dessen Platten wie im EP 0 992 756 A2 beschrieben ist, verformt und aufeinander gestapelt sind, wobei die Platten flache Wärmetauscherrohre 2 bilden. Bezüglich weiterer Einzelheiten dieser Bauweise wird auf das EP verwiesen, das an dieser Stelle als umfassend beschrieben gelten soll.
Es handelt sich um einen mittels Kühlflüssigkeit gekühlten Abgaswärmetauscher, der in nicht gezeigter Weise in das Abgasrückführungssystem eines Kraftfahrzeuges eingebunden ist. Mit den gleichen Vorteilen ist der Wärmetauscher als mittels Kühlflüssigkeit gekühlter Ladeluftkühler zu verwenden.
Gemäß den Fig. 2 und 3 besitzt der Abgaswärmetauscher Wärmetauscherrohre 2, die an den einen Enden 4 einen Diffusor 1 und an den anderen Enden 4 einen Sammelkasten 1 aufweisen. In Fig. 3 sollen die eingezeichneten Pfeile anzeigen, dass das Abgas oben in den Abgaswärmetauscher über den Diffusor 1 einströmt und unten über den Sammelkasten 1 ausströmt. Über den Einlassstutzen 20 strömt Kühlflüssigkeit in den Abgaswärmetauscher, die denselben nach erfolgtem Wärmeaustausch mit dem Abgas über den Auslassstutzen 21 wieder verlässt. Auf der gezeigten Oberseite und auf der nicht zu sehenden Unterseite des Abgaswärmetauschers ist jeweils eine Abschlussplatte 22 angeordnet worden, die den Abgaswärmetauscher verstärkt. An den gegenüberliegenden Enden der Abschlussplatten 22 sind beidseitig Laschen 23 hochgestellt worden. An den zwei gegenüberliegenden Breitseiten der Wand 3 des Diffusors 1 sind Verlängerungen 24 vorgesehen, die eine Abstufung 25 aufweisen. (Fig. 6) Wie die Fig. 2 zeigt, ragen die Verlängerungen 24 bis über die Enden der Abschlussplatte 22. Die Laschen 23 werden anschließend auf die Verlängerung 24 heruntergebogen, so dass der Stapel zum Löten vorfixiert ist.The invention is described below in one embodiment with reference to the accompanying drawings.
The figures show the following:

Fig. 1

Section l - l of Fig. 3;

Fig. 2

perspective view of the heat exchanger with diffusers to be attached;

Fig. 3

perspective view of the heat exchanger with attached diffusers;

4 and 5

Top views of a diffuser;

Fig. 6

perspective view of a diffuser;

7 to 15 show a further inventive design of the heat exchanger with a diffuser in several perspective views.
In the exemplary embodiment, a housing-free heat exchanger consisting of a plate stack is shown, the plates of which, as described in EP 0 992 756 A2, are deformed and stacked on top of one another, the plates forming flat heat exchanger tubes 2 . With regard to further details of this construction, reference is made to the EP, which is to be considered as being comprehensively described at this point.
It is an exhaust gas heat exchanger cooled by means of coolant, which is integrated in a manner not shown in the exhaust gas recirculation system of a motor vehicle. With the same advantages, the heat exchanger can be used as an intercooler cooled by coolant.
Referring to FIGS. 2 and 3, the exhaust gas heat exchanger the heat exchanger tubes 2 having at one ends 4 a diffuser 1 and at the other ends 4 a collecting tank 1 has. In FIG. 3, the arrows drawn in indicate that the exhaust gas flows into the exhaust gas heat exchanger at the top via the diffuser 1 and flows out at the bottom via the header box 1 . Cooling fluid flows into the exhaust gas heat exchanger via the inlet connector 20 , which coolant exits via the outlet connector 21 after the heat exchange with the exhaust gas has taken place. On the upper side shown and on the underside of the exhaust gas heat exchanger, which cannot be seen, an end plate 22 has been arranged, which reinforces the exhaust gas heat exchanger. Tabs 23 have been raised on both sides at the opposite ends of the end plates 22 . On the two opposite broad sides of the wall 3 of the diffuser 1 , extensions 24 are provided which have a gradation 25 . (FIG. 6) As FIG. 2 shows, the extensions 24 protrude beyond the ends of the end plate 22 . The tabs 23 are then bent down onto the extension 24 , so that the stack is pre-fixed for soldering.

In the exemplary embodiments shown, the stack consists only of two heat exchanger tubes 2 . The number of heat exchanger tubes 2 depends on the application and is therefore arbitrary. As shown in FIG. 1, an inner insert 26 is arranged in both heat exchanger tubes 2 in order to generate turbulence in the exhaust gas and thus to achieve an efficient heat exchange. The heat exchanger tubes 2 consist of two flat tube halves 2a and 2b . The flat tube halves 2a and 2b have an edge flange 12 and are connected to one another at this edge flange 12 . The edge flanges 12 form the projections 9 on the circumference of the stack. Since in this exemplary embodiment the heat exchanger tubes 2 are also connected to one another on their broad sides 15 , furrows 10 also occur in the periphery of the stack, which are present exactly in the seam area. Their size depends on the bending radius on the flat tube halves 2a , 2b . A smaller bending radius leads to smaller furrows 10 , although smaller bending radii are more difficult to implement. If the furrows 10 are too large, problems arise in soldering the wall 3 close to the circumference of the stack. For this reason, 3 recesses 8 (inwardly projecting lugs 13 ) are provided in the wall, which extend into the furrows 10 and essentially fill them and thus permit a tight solder connection at these points. If the flat tube halves 2a , 2b do not have, as shown and described, edge flanges 12 projecting outwards, which are projections 9 on the circumference of the stack, but are edge flanges 12 projecting into the tube interior, then such well-known edge flanges, not shown, lead also for the formation of furrows 10 in the circumference of the stack. Such furrows 10 , not shown, can also be closed by means of a corresponding arrangement of depressions 8 (lugs 13 ) in the wall 3 . In addition, cross-sectionally U-shaped flat tube halves 2a , 2b could be stacked one inside the other so that the legs of one flat tube half point upward and the legs of the other flat tube half point downward, as is shown and described in DE 39 04 250 C2, for example. With such a type of connection, shoulders are formed on the circumference of the stack, which should be regarded as equivalent to the furrows 10 and which can also be compensated for by means of corresponding depressions 8 in the wall 3 .

In addition, elevations 6 are provided in the wall, which are designed as folds 11 . The dimensions of the folds 11 are such that one of the above-mentioned projections 9 or one of the outwardly projecting edge flanges 12 fits into a fold 11 and a tight solder connection is thus also created there. The folds 11 can also be designed as slots 7 in the wall 3 , which represent an equivalent solution. The depth of the slots 7 in the wall 3 depends on how far the diffuser 1 is pushed onto the ends 4 of the heat exchanger tubes 2 . In Fig. 1, a slot 7 was indicated at the bottom right. The slot 7 does not have to represent an elevation 6 , as shown, because it could also be present in the undeformed wall 3 and fulfill its purpose. Of course, slots 7 and folds 11 could also be combined as desired. The slots 7 or elevations 6 or depressions 8 are located in the wall sections of the diffuser 1 , which extend along the two narrow sides of the flat heat exchanger tubes 2 . The broad sides of the diffuser 1 , just like the broad sides of the flat heat exchanger tubes 2 , are flat.
In another exemplary embodiment, in the case of a plate heat exchanger, there is a distance between the broad sides 15 of the flat heat exchanger tubes 2 , as was indicated by reference number 27 in FIG. 2 for better understanding. There, the depressions 8 in the wall 3 are unnecessary because there are no furrows 10 to be sealed on the circumference. The distance 27 mentioned corresponds approximately to the height of the flow channels for the cooling liquid, not shown here, which are also closed in terms of flow technology by the deformation of the flat tube halves 2a , 2b, not shown here. Again, reference is made to EP 0 992 756 A2.
FIG. 7 shows a side view and FIG. 8 shows the top view of a further developed heat exchanger. This heat exchanger also has a diffuser 1 , in which the wall 3 extends all around the entire circumference of the end of the stack and has elevations 6 , which correspond to projections 9 on the circumference of the stack, in order to provide a tight connection between the circumference and the wall 3 to ensure, wherein the wall 3 has at least one inlet 20 or an outlet 21 for the other medium, which flows between the heat exchanger tubes 2 .

The wall 3 can - but need not necessarily - also have depressions 8 which correspond to furrows 10 on the circumference of the stack. This will depend on how sharp the flat tube halves 2a , 2b are formed and whether the furrows 10 formed are so large that they have to be filled with the depressions 8 in order to be able to carry out a quality-appropriate soldering process. The wall 3 has a circumferential extension 30 , in which the inlet 20 or the outlet 21 is arranged. The two flat tube halves 2a , 2b forming the heat exchanger tubes 2 are deformed in the region of the peripheral extension 30 in such a way that a hydraulic connection is created between the peripheral extension 30 and the flow channels 40 arranged between the heat exchanger tubes 2 for the other medium. This other medium is the coolant. The inlet 20 or the outlet 21 can be arranged at any desired points on the circumference in the circumference widening 30 , which gives rise to design freedoms in this regard which must be attributed to the invention. In the embodiments shown, the inlet 20 or the outlet 21 have a round cross section and a drawn edge 80 (FIG. 9) around the opening in order to be able to attach a suitable connecting piece there. Other designs have an approximately rectangular cross-sectional shape. The present invention is also to be understood in such a way that the heat exchanger can be flowed through in a U-shape, the inlet 20 and the outlet 21 being located on one and the same diffuser 1 .
In the embodiments shown, the depressions 8 already mentioned are only provided on one side of the circumferential extension 30 , specifically on the side which points to the inlet or the outlet for the exhaust gas. With regard to the opposite side, it can be seen from FIG. 10 that a locally sharp-edged formation 50 on the flat tube halves 2a , 2b has provided for a very small furrow 10 , as a result of which a depression 8 on this side of the circumferential extension 30 is unnecessary. The sharp-edged design 50 also allows the bending edges, designated 70 , in the wall 3 of the diffuser 1 to be soldered to the outer edges of the stack of heat exchanger tubes 2 in accordance with the quality. The problem areas from the point of view of the soldering technique are often located in these edges 70 .
The elevations 6 in the wall 3 are interrupted in the area of the circumferential extension 30 . What is to be understood by this can be clearly seen from FIG. 7 but also from FIGS. 9 and 11-13, where the elevations 6 are provided on the left and right of the circumferential extension 30 , in each case by the edge flange 11 of the two Flat tube halves 2a , 2b formed projection 9 .

10, because this further development of the diffuser 1 requires or permits a different configuration of the flat tube halves 2a , 2b , which can be seen from this FIG. 10, which offers a view into the interior of the heat exchanger because there - in contrast to Fig. 9 - the diffuser 1 has been omitted. FIG. 10 shows that the two flat tube halves 2a , 2b in the end region, which is surrounded by the wall 3 of the diffuser 1 , are shaped such that a hydraulic connection to the flow channels 40 between the heat exchanger tubes 2 is achieved. The flow channels 40 have been realized by the special shaping of the flat tube halves 2a , 2b , as can also be seen from FIG. 14, which shows a section in the longitudinal direction of the heat exchanger in the region of the diffuser 1 . A relatively wide transverse bead 60 in the flat tube halves offers excellent soldered connections, both between the inside of the wall 3 of the diffuser 1 and between the individual flat tube halves 2a and 2b . The remaining figures speak for themselves, which is why further explanations seem to be unnecessary. 11-13 show the diffuser 1 as an individual part from different angles. FIG. 15, which also shows a longitudinal section through the heat exchanger in the area of the diffuser 1 , differs from FIG. 14 in that only a single heat exchanger tube 2 has been drawn in, as a result of which other details are better visible. The number of heat exchanger tubes 2 depends on the application, as already mentioned in the introduction. Restrictions are not discernible, and if they were, they were not intended.

Claims (16)

Heat exchanger with a diffuser (1) to introduce a medium into flat heat exchanger tubes (2) or with a collecting box to take up and convey a medium out of the flat heat exchanger tubes (2), the diffuser (1) having a wall (3) which extends along the ends (4) of a stack of flat heat exchanger tubes (2) and whose inside (5) is tightly connected to the ends (4) by means of soldering,
characterized in that
the wall (3) extends all the way around the entire circumference of the end of the stack and has depressions (8) and / or slots (7) and / or elevations (6) such that the depressions (8) with grooves (10) in the circumference of the stack correspond, and that the elevations (6) and / or slots (7) correspond to projections (9) on the circumference of the stack in order to ensure a tight connection between the circumference and the wall (3). Heat exchanger according to claim 1, characterized in that each elevation (6) in the wall (3) is a fold (11), each fold (11) receiving a projection (9) therein from which the edge flange (12) is made two flat tube halves (2a, 2b) existing heat exchanger tubes (2). Heat exchanger according to claim 1, characterized in that each recess (8) in the wall (3) is an inwardly projecting nose (13) which is the groove between the two heat exchanger tubes (2) and which represents a furrow (10) on the circumference of the stack ) fills out. Heat exchanger according to claim 1, characterized in that each slot (14) in the wall (3) is dimensioned so that it receives a projection (9) which the edge flange (12) of the two flat tube halves (2a, 2b) Heat exchanger tubes (2). Heat exchanger according to claims 1 to 4, characterized in that the ends (4) on the broad sides (15) of the flat heat exchanger tubes (2) abut each other and are to be connected, the joints (10) (furrows) the edge seams between two Are heat exchanger tubes (2). Heat exchanger according to the preceding claims, characterized in that the elevations (6) and / or depressions (8) and / or slots (7) are arranged in the wall sections of the wall (3) which extend along the narrow sides of the flat heat exchanger tubes (2 ) extend. Heat exchanger according to claims 1 to 4 or 6, characterized in that; that a gap (27) is present between the broad sides (15) at the ends (4) of the flat heat exchanger tubes (2). Heat exchanger according to one of the preceding claims, characterized in that the wall (3) of the diffuser (1) or the collecting tank has two narrow walls and two wide walls, that preferably the wide walls have extensions (24) which extend to the ends of end plates (22 ) which cover and reinforce the stack of flat heat exchanger tubes (2). Heat exchanger according to claim 8, characterized in that the extensions (24) have a step (25). Heat exchanger according to claims 8 and 9, characterized in that the end plates (22) have tabs (23) at the ends, which are bent after the preassembly of the heat exchanger in order to rest on the extensions (24). Heat exchanger according to the preceding claims, characterized in that the diffuser (1) is a part produced by deep drawing. Heat exchanger according to one of the preceding claims, characterized in that it is used as a liquid-cooled exhaust gas heat exchanger in exhaust gas recirculation systems of motor vehicles or as an intercooler. Heat exchanger with a diffuser (1) to introduce a medium into flat heat exchanger tubes (2) or with a collecting box to take up and convey a medium out of the flat heat exchanger tubes (2), the diffuser (1) having a wall (3) which extends along the ends (4) of a stack of flat heat exchanger tubes (2) and whose inside (5) is tightly connected to the ends (4) by means of soldering,
characterized in that
the wall (3) extends circumferentially around the entire circumference of the end of the stack and has elevations (6) and / or slots (7) which correspond to projections (9) on the circumference of the stack in order to provide a tight connection between the circumference and to ensure the wall (3), the wall (3) having at least one inlet (20) and / or an outlet (21) for the other medium which flows between the heat exchanger tubes (2). Heat exchanger according to claim 13, characterized in that the wall (3) has depressions (8) which correspond to furrows (10) on the circumference of the stack. Heat exchanger according to claim 13, characterized in that the wall (3) has a circumferential extension (30) in which the inlet (20) and / or the outlet (21) is arranged, and in that the two forming a heat exchanger tube (2) Flat tube halves (2a, 2b) in the area covered by the peripheral extension (30) are deformed such that a hydraulic connection between the peripheral extension (30) and the flow channels (27, 40) arranged between the heat exchanger tubes (2) for the other medium is created. Heat exchanger according to one of claims 13 - 15, characterized in that the elevations (6) and / or slots (7) in the wall (3) are interrupted in the region of the peripheral extension (30).

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