EP1491837A2 - Plate heat exchanger without casing - Google Patents

Abstract

The motor vehicle exhaust gas heat exchanger has a flow switching valve (20) in one manifold (4,5). At least the main part of the gas stream passing through the cooled flat tube (3) or through at least one non-cooled flat tube is steerable via the valve. Separation between the cooled tubes and at least uncooled tube is through a closure for the channels in at least one of the plates (1,2).

Description

The invention relates to a heat exchanger in a housing-less plate construction, in which two deformed plates each form a flat tube, which are stacked, an inlet header box in the manner of a diffuser at one end of the stack of flat tubes and an outlet header box at the other end, for example for exhaust gas or charge air , which flows through the flat tubes and is thereby cooled by means of coolant which can be introduced and discharged via ducts extending into the stack, the ducts being formed by means of connected openings in the deformed plates and the ducts being between existing flow channels are hydraulically connected to the flat tubes.

This housing-free heat exchanger has already been described in the previously unpublished German application DE 102 29 083.0 and in the European application with the application number EP 03 007 724.2. Such heat exchangers are extremely compact and have very good functional properties.

The housing-free plate construction described above is also apparent from EP 992 756 B1 belonging to the applicant.

These heat exchangers are currently in high demand as exhaust gas heat exchangers because exhaust gas recirculation is increasingly being used to reduce emissions in motor vehicles. The recirculated exhaust gas has to be cooled in order to achieve high efficiency in the recirculation, in particular in order to achieve better filling levels. Of course, it is about the overall "motor vehicle with internal combustion engine" system and an overall significantly reduced energy balance. For this reason, many operating situations in the motor vehicle were analyzed many years ago and measures were taken to meet all operating situations. One of these measures is to bypass the exhaust gas heat exchanger in operating situations in which the cooling of the exhaust gas would be counterproductive. Such operating situations are, in particular, the extremely high fuel-consuming starting phases of the motor vehicle, in which the thermal energy of the exhaust gases is used, for example, directly for quickly warming up the engine to its optimum operating temperature. To circumvent the exhaust gas heat exchanger, solutions are usually provided, as are described, for example, in European patent applications / patents EP 916 837 and EP 987 427. There is a valve before the entry of the exhaust gases into the exhaust gas heat exchanger, with which the exhaust gas flow, if necessary, through the Exhaust gas heat exchanger or past it, directly into the return line. The bypass is integrated there in the valve. In the German applications DE 197 33 964 A1 or DE 199 06 401 A1, further solutions have been described which show how the return can also be done. In the former document, a bypass line and the exhaust gas heat exchanger are separated from each other, but both are apparently arranged in a common housing and in the latter the bypass line goes around the outside of the exhaust gas heat exchanger without both being surrounded by a housing. The exhaust gas heat exchangers themselves appear to be so-called tube bundle heat exchangers or spiral tube heat exchangers, that is to say, heat exchangers of completely different construction than those from the generic term. These exhaust gas heat exchangers do not appear to be particularly compact, that is to say they are space-saving.

In exhaust gas heat exchangers per se, that is to say those which were proposed decades ago and were used and are used in heating systems for motor vehicle cabins, bypassing the same with a bypass is generally also necessary, u. a. this is because the heating requirement is not permanently available. However, these exhaust gas heat exchangers also usually belong to the tube bundle type or the spiral tube type. These include exhaust gas heat exchangers, as can be found, for example, in EP 942 156 A1.

Other solutions with integrated bypasses, which, however, do not relate to heat exchangers in a housing-free plate construction and therefore often have to be produced by means of complex welding processes, have been described in DE 101 42 539 A1, DE 199 62 863 A1 and DE 195 40 683 A1.

In conclusion from the introduction to the description above, the object of the invention is to design heat exchangers in a housing-free plate construction with a possibility of bypassing, for example by means of exhaust gas or charge air, in such a way that the exemplary functional properties and the compactness are retained, and that they remain above all easy to manufacture.

The solution according to the invention takes place in a heat exchanger corresponding to the preamble either with the characterizing features of claim 1 or with the characterizing features of claim 2. According to the second variant, a changeover valve is provided in one of the header boxes is arranged, with which at least the major part of the exhaust gas flow to be recirculated can be steered either through a plurality of cooled flat tubes of the stack or through at least one uncooled flat tube, an insulation plate being arranged between the cooled and the at least one uncooled flat tube, which has a deformed plate of the at least one uncooled flat tube and is connected to a deformed plate of a cooled flat tube. According to the first independent solution to the problem, the insulation plate can be dispensed with, in that, according to the invention, a changeover valve is arranged in one of the collecting tanks, by means of which at least the majority of the exhaust gas flow to be returned can be directed either through a plurality of cooled flat tubes of the stack or through at least one uncooled flat tube, wherein a separation between the cooled flat tubes and the at least one uncooled flat tube is provided by the closure of the openings forming the channels in at least one of the adjacent deformed plates.

Both proposed solutions additionally have a non-flowed-through space. This space is provided with the insulation plate between this plate and an adjacent deformed plate, and in the case without an insulation plate, the space is preferably formed between two deformed plates.

Both proposed solutions solve the task independently, because they aim for a manufacturing-friendly and compact heat exchanger in a housing-free plate construction.

However, both proposed solutions can also be implemented together on one and the same heat exchanger. In any case, claims 1 and 2 should be understood in such a way that an insulation plate can be provided according to claim 2 and in addition the openings can be closed according to claim 1, for example not punched out. In addition, the closure can also be produced by inserting closure plates into the openings.

Although the provision of an uncooled flat tube for the purpose of bypassing the heat exchanger in heat exchangers with a housing is part of the prior art, it was not obvious to transfer this idea to housing-free plate heat exchangers, because it was not to be expected that this measure would also be done with simple means housing-less plate heat exchangers is feasible without having to give up their undeniable advantages.

Each of the deformed plates is provided with a circumferential shape, as has already been shown and described in EP 992 756 B1, to which reference is expressly made here without having to repeat all details here. In addition, the EP with the application no. 03 007 724.2, where certain features of the diffuser are shown and described. Two deformed plates are put together to form a flat tube and the flat tubes are put together to form a stack. Two deformed plates come together with their peripheral shape and enclose a space that represents a flow channel for a preferably liquid coolant. This design is described in more detail in the European patent mentioned.

It is advantageous if the cooled and the uncooled flat tubes are assembled from the same deformed plates. However, there is still the possibility of forming the at least one uncooled flat tube from other deformed plates. For example, the uncooled flat tube can have a larger cross section than a cooled flat tube.

In the proposed solution, which requires an insulation plate, it is advantageous if the insulation plate has an end which projects beyond the stack and which interacts with the changeover valve, in particular with the flap of the changeover valve.

The wall of the header box, in which the changeover valve is located, has two opposite openings in which the changeover valve can be mounted after the heat exchanger has been soldered. It is particularly advantageous of the proposed solutions that the entire exhaust gas heat exchanger, for example, can still be connected or manufactured in a single soldering operation, in spite of the integrated changeover valve. The individual parts of the exhaust gas heat exchanger are held together by the header boxes pushed over the ends of the flat tubes. Elaborate welding operations, such as are necessary with state-of-the-art heat exchangers, are totally avoided. For further features, reference is made to the dependent claims.

Fig. 1

perspektivische Explosionsdarstellung des Wärmetauschers;

Fig. 2

Draufsicht auf einen Wärmetauscher;

Fig. 3

Querschnitt durch einen Wärmetauscher;

Fig. 4

Alternative zur in Fig. 3 gezeigten Lösung;

Fig. 5

Längsschnitt durch einen Wärmetauscher mit Isolationsplatte;

Fig. 6

Längsschnitt durch einen Wärmetauscher ohne Isolationsplatte;

The invention is described below in an exemplary embodiment. This description may give rise to additional features and advantages that may later prove to be particularly important.

Fig. 1

perspective exploded view of the heat exchanger;

Fig. 2

Top view of a heat exchanger;

Fig. 3

Cross section through a heat exchanger;

Fig. 4

Alternative to the solution shown in FIG. 3;

Fig. 5

Longitudinal section through a heat exchanger with an insulation plate;

Fig. 6

Longitudinal section through a heat exchanger without an insulation plate;

In the exemplary embodiment shown, it is an exhaust gas heat exchanger for a motor vehicle that is cooled by means of coolant of the internal combustion engine.

The exhaust gas heat exchanger is constructed in a housing-free plate construction. The flat tubes 3 of the exhaust gas heat exchanger consist of deformed plates 1, 2 . The deformed plates 1, 2 have a circumferential shape 80 . Two deformed plates 1, 2 each form a flat tube 3, for which purpose one of the plates 1 or 2 is rotated through 180 ° about its longitudinal axis and is assembled with the other plate to form a flat tube 3 "edge 102 on edge 102" . The flat tubes 3 are then stacked one on top of the other, the formation 80 on the plate 1 or 2 of the one flat tube 3 coming into contact with the formation 80 on the plate 1 or 2 of the adjacent flat tube 3 . Only two cooled flat tubes 3 and only one uncooled flat tube 3 were shown in the exemplary embodiments. It is expedient to provide the cooled flat tubes 3 with an inner insert 99 , as is indicated in FIG. 3. It is clear that the number of flat tubes 3 is chosen, for example, according to the respective performance requirements. At one end of the stack of flat tubes 3 , a collecting box 4 is arranged in the manner of a diffuser. At the other end a collecting box 5 , not shown, is provided. Both collecting boxes 4, 5 can be identical, except for the differences caused by the changeover valve 20 , which are explained further below. The exhaust gas flows through the flat tubes 3 and is thereby cooled by means of the cooling liquid which can be introduced and discharged via channels 10 extending into the stack. The channels 10 are formed by means of connected openings 11 in the deformed plates 1, 2 . To connect the openings 11 , pull-throughs 81 that can be produced by shaping are arranged around each opening 11 in the exemplary embodiment. The connection of the passages 81 results in the channels 10 which pass vertically through the heat exchanger. (Fig. 3, 4) At the same time there is between the flat tubes 3 , within those already mentioned circumferential formation 80 , each a flow channel 12 , each of the flow channels 12 being hydraulically connected to the channels 10 . 1, dashed arrows have been drawn in, which indicate the exhaust gas, wherein the exhaust gas at the collecting box 4 shown can either be introduced or discharged. Therefore arrows with the opposite flow direction were drawn. The arrows with solid lines are intended to indicate the path of the coolant, which in the exemplary embodiment is introduced at the inlet connection 40 , penetrates into the duct 10 there, not shown in FIG. 1, is distributed over the flow ducts 12 , in order to form in the duct 10 shown collect and leave the heat exchanger via the outlet connection 50 after the heat has been exchanged with the exhaust gas.

Arranged in the collecting box 4 is a changeover valve 20 with which at least the predominant portion of the exhaust gas flow to be recirculated can be directed either through a plurality of cooled flat tubes 3 of the stack or through at least one uncooled flat tube 3 . An insulation plate 30 is arranged between the cooled and the at least one uncooled flat tube 3 . The essentially flat insulation plate 30 is connected on one side to a deformed plate 1 of the at least one uncooled flat tube 3 and on the other side to a deformed plate 2 of the adjacent cooled flat tube 3 . Specifically, the connection mentioned looks such that the insulation plate 30 bears against and is connected to the peripheral shape 80 of the two deformed plates 1, 2 . Therefore, within the space surrounded by the circumferential shape 80 between the insulation plate 30 and the deformed plates 1, 2, a non-flow-through space 101 remains which has thermally insulating properties. (FIG. 3) The circumferential shape 80 is approximately U-shaped in cross section, as best shown in FIGS. 3 and 4.

The heat exchanger has a cover plate 60 and a base plate 70 , which are also deformed and have a somewhat larger sheet thickness than the deformed heat exchanger plates 1 and 2, in order to provide additional stability. Furthermore, the base plate 70 and the cover plate 60 were assigned a holding or fastening function for the changeover valve 20 and for the actuating element 21 of the changeover valve 20 . For this purpose, the base plate 70 and the cover plate 60 are each provided with a projection 90. The switching valve 20 and the actuating element 21 are mounted on the projections 90 by means of a holder 91 . (Fig. 1)

For the purpose of assembling the changeover valve 20 - after soldering the exhaust gas heat exchanger - two opposite openings 15, 16 have been provided in the wall 14 of the collecting tank 4 . In these openings 15, 16 , as shown in FIG. 1, bearing bushes 17, 18 are inserted and fastened for a rotatable shaft 19 , on which the flap 22 of the changeover valve 20 is located. Furthermore, a functional element 23 cooperating with the flap 22 was inserted into the collecting box 4 in order to support the action of the flap 22 . The type of interaction can be seen from FIG. 5. From Fig. 5 it can also be seen that, in the variant which provides an insulation plate 30 for the separation between the cooled and the uncooled flat tubes 3 , the end 31 of the insulation plate 30 has been extended, this extended end 31 also with the flap 22 cooperates. It is advantageous not to design the flap 22 too large because rattling noises or other functional disadvantages caused by the flow of the exhaust gas can occur. The flap 22 can be made smaller by the interaction with the end 31 of the insulation plate 30 and with the functional element 23 , as can be seen from FIG. 5.

The already mentioned diffuser 4 also has in its wall 14 formations 103 (FIG. 1) which are intended to accommodate two edges 102 (FIG. 4) at the end of the deformed plates 1, 2 of a flat tube 3 . As a result, the entire stack of flat tubes 3 is held together and soldering in a single operation without additional auxiliary devices is made possible. Further details on this have been described in EP Application No. 03 007 724.2.

FIG. 3 is a cross section through both channels 10 for the cooling liquid through an exhaust gas heat exchanger of the type shown in FIG. 1. 4 is only intended to illustrate the difference between the two solutions described. 4, the separation of the cooling liquid from the uncooled flat tube 3 was created in that the openings 11 in the deformed plate 1 and / or 2 were provided with a closure 100 . The closure can either be done by inserting an insert (not shown) into the corresponding passage 81, which surrounds the opening 11 , or by not opening the openings 11 in this deformed plate 1 and / or 2 . In the variant shown in FIG. 4, the insulation plate 30 can therefore be dispensed with, although the same is shown in FIG. 4.

The crossed-out reference symbol 30 is intended to indicate that the insulation plate 30 can be omitted, but does not necessarily have to be omitted, because the functionality is also retained with the insulation plate 30 . The space 101 through which there is no flow is larger in this solution than in the previously described first solution.

FIG. 6 is a longitudinal section through a heat exchanger of the type according to FIG. 4, that is to say a heat exchanger in which the separation between the cooled and the uncooled flat tubes 3 has been realized by closure 100 of the openings 11 . In contrast to the exemplary embodiment described above from FIGS. 1 and 3, no insulation plate 30 is necessary there. Depending on the selected valve construction 20 , a partition 32 or the like can be provided in the collecting box 4 in order to support the valve function. This partition wall 32 is functionally equivalent to the protruding end 31 of the insulation plate 30 from FIGS. 1 and 5.

Only exemplary embodiments were shown in which the cooled and uncooled flat tubes 3 - that is to say all the flat tubes 3 - consist of the same deformed plates 1, 2 , which has manufacturing advantages. Nevertheless, it can be expedient to produce the uncooled flat tubes 3 from plates other than the cooled flat tubes 3 , which is permitted by the proposed solutions, which is why the solutions according to the invention also provide a certain flexibility in design.

Claims (13)

Heat exchanger in a housing-free plate construction, in each of which two deformed plates (1, 2) form a flat tube (3) which are stacked, with an inlet header box (4) in the manner of a diffuser at one end of the stack of flat tubes (3) and at the other end there is an outlet header (5), for example for exhaust gas or charge air, which flows through the flat tubes (3) and is thereby cooled by means of coolant which can be introduced and discharged via channels (10) extending into the stack , the channels (10) being formed by means of connected openings (11) in the deformed plates (1, 2) and the channels (10) being hydraulically connected to flow channels (12) present between the flat tubes (3),
characterized in that
A changeover valve (20) is arranged in one of the collecting boxes (4, 5), with which at least the majority of the gas flow to be conducted through the flat tubes either through a plurality of cooled flat tubes (3) of the stack or through at least one uncooled flat tube (3 ) is steerable, whereby a separation between the cooled flat tubes (3) and the at least one uncooled flat tube is provided by a closure (100) of the openings (11) forming the channels (10) in at least one of the adjacent deformed plates (1, 2) and a non-flow-through space (101) is present between the deformed plates (1, 2, 60). Heat exchanger in a housing-free plate construction, in each of which two deformed plates (1, 2) form a flat tube (3) which are stacked, with an inlet header box (4) in the manner of a diffuser at one end of the stack of flat tubes (3) and at the other end there is an outlet header (5), for example for exhaust gas or charge air, which flows through the flat tubes (3) and is thereby cooled by means of coolant which can be introduced and discharged via channels (10) extending into the stack , the channels (10) being formed by means of connected openings (11) in the deformed plates (1, 2) and the channels (10) being hydraulically connected to flow channels (12) present between the flat tubes (3),
characterized in that
A changeover valve (20) is arranged in one of the collecting boxes (4, 5), with which at least the majority of the gas flow to be conducted through the flat tubes (3) either through a plurality of cooled flat tubes (3) of the stack or through at least one uncooled one Flat tube (3) is steerable, a separation between the cooled and the at least one uncooled flat tube (3) being provided by means of an insulation plate (30) which is connected to a deformed plate (1, 2) of the at least one uncooled flat tube (3) and is connected to the adjacent deformed plate (1, 2) of a cooled flat tube (3), a space (101) not flowed through remaining between the insulation plate (30) and the deformed plate (1, 2). Heat exchanger according to claim 1 or 2, characterized in that the cooled and uncooled flat tube (s) (3) have essentially the same configuration or are formed from the same plates (1, 2). Heat exchanger according to claim 1 or 2, characterized in that the at least one uncooled flat tube (3) has a larger cross section than one of the cooled flat tubes (3). Heat exchanger according to the preceding claims, characterized in that the deformed plates (1, 2) have a circumferential shape (80) with which two adjacent plates (1, 2) are connected to each other, one inside the circumferential shape (80) Space is available, which is one of the flow channels (12) for the coolant, preferably for liquid, in the cooled flat tubes (3). Heat exchanger, in particular according to claim 2, 3 and 5, characterized in that the insulation plate (30) is essentially a flat plate, on one side with the peripheral shape (80) of a deformed plate (1, 2) and on the other Side is connected to the circumferential deformation (80) of the next deformed plate (1, 2), the non-flow-through space (101) being formed between the insulation plate (30) and the uncooled flat tube (3). Heat exchanger, in particular according to claims 2 and 6, characterized in that the non-flow-through space (101) within the peripheral shape (80) and the insulation plate (30) has thermally insulating properties. Heat exchanger according to claims 2, 6 and 7, characterized in that the insulation plate (30) projects beyond the end of the stack, and that the projecting end (31) of the insulation flap (30) interacts with the changeover valve (20). Heat exchanger according to one of the preceding claims, characterized in that an inner insert (99) is arranged in the cooled flat tubes (3). Heat exchanger, in particular according to claims 1, 2 or 5, characterized in that the space (101) within the peripheral formation (80) between the plates (1, 2) at the level of the separation between cooled and uncooled flat tubes (3) thermally has insulating properties. Heat exchanger according to one of the preceding claims, characterized in that the changeover valve (20) is a flap valve known per se, the flap axis of which is arranged approximately at the level of the end (31) of the insulation plate (30) or of the separation and runs approximately parallel to it . Heat exchanger according to one of the preceding claims, characterized in that the flap (22) together with the end of the insulation plate (30) can either close the cooled or the at least one uncooled flat tube (3). Heat exchanger according to one or more of the preceding claims, characterized in that the collecting box (4 or 5) in which the changeover valve (20) is located, in its wall running around the entire end of the stack of compartment tubes (3) and pre-fixing the stack ( 14) has two mounting openings (15, 16) on opposite sides of the wall (14), the changeover valve (20) being mountable in the mounting openings (14, 15) after the exhaust gas heat exchanger has been soldered.

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