BRAZED HEAT EXCHANGER

Abstract

A heat exchanger from a stack of plate pairs having fins which are disposed between the plate pairs, and having ducts which vertically extend through the stack, for conveying in and/or conveying out a medium which flows through the plate pairs and which exchanges heat with another medium which flows through the fins, wherein the ducts are formed from openings in the plates and have moldings which extend around opening peripheries, and having a plate, having corresponding openings, which finishes off the stack, wherein a thermally decoupling element, which is inserted either in an integrated or a separate manner and which is incorporated into the vertical duct formation, is disposed between the finishing-off plate and the stack. Such a heat exchanger displays improved resilience to alternating temperature loadings.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to German Patent Application No. 10 2014 002801, filed Feb. 26, 2014, the entire contents of which are hereby incorporated by reference herein.

FIELD OF THE INVENTION

The invention relates to a brazed heat exchanger from a stack of plate pairs and fins which are disposed between the plate pairs, and having ducts which vertically extend through the stack, for conveying in and conveying out a medium which flows through the plate pairs and which exchanges heat with another medium which flows through the fins, wherein the ducts are formed from openings in the plates and have moldings which extend around the opening peripheries of said openings, and having a plate, having corresponding apertures, which finishes off the stack.

BACKGROUND

A brazed heat exchanger has been depicted in the older patent application having the file number DE 10 2013 015 179.1, FIGS. 3 and 8. In this heat exchanger, a further but thinner plate has been disposed directly below the finishing-off plate. In this thinner plate, openings having moldings which extend around the opening peripheries of said openings and which, by way of the abovementioned moldings are brazed, as is the entire heat exchanger, to the adjacent first plate of the first plate pair, are likewise located.

In the case of this heat exchanger, deficiencies with regard to the resilience to alternating temperature loadings due to operational reasons have been observed in the course of testing.

SUMMARY

The object of the invention consists in improving the brazed heat exchanger mentioned at the outset with regard to its resilience to alternating temperature loadings due to operational reasons.

It has been determined in the mentioned test that cracks or fractures mainly arise below the finishing-off plate, specifically toward the adjacent moldings.

On account of the provision according to one embodiment of the invention of a thermally decoupling element which is disposed between the finishing-off plate, around the corresponding opening of the latter and toward an adjacent molding, cracks or fractures which are induced by alternating temperature loadings due to operational reasons are eliminated or at least significantly reduced, as has been demonstrated by further testing undertaken in the meantime. The thermally decoupling element may be inserted as an individual part. The thermally decoupling element, however, may also be a specially transformed region of a further plate, that is to say be integrally configured with the mentioned further plate. The further plate is located below the finishing-off plate.

The thermally decoupling element is a flat, plate-like element, the contour of which approximately corresponds to the contour of a molding.

The inventors have established that by means of the thermally decoupling elements(s), variable expansions on account of thermal loadings in the finishing-off plate and in the adjacent plate of the plate pair can be largely compensated for, on account of which the effects described above arise.

The invention will be explained in the following with exemplary embodiments by means of the appended drawings. Further features and advantages of the invention emerge from this description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a preferred exemplary embodiment, in a view onto part of a heat exchanger.

FIG. 2 shows this exemplary embodiment in another view.

FIGS. 3 and 4 show a second exemplary embodiment.

FIGS. 5 and 6 show a third exemplary embodiment.

FIG. 7 shows a substantial part of another heat exchanger in which the invention has been implemented.

FIG. 8 shows the heat exchanger according to FIG. 1, 3 or 5, inserted into an intake pipe of an internal combustion engine that represents a housing.

DETAILED DESCRIPTION

The appended FIGS. 1 to 6 show practical views onto one of two sides, for example narrow sides, of the brazed heat exchanger. Visible are two vertical ducts 3 and 4, wherein these may be ducts 3, 4 for a medium, for example for a coolant, which flows within the plate pairs 10 and/or through the plate pairs 10.

It may be assumed here that the other side, for example narrow side, not shown, is configured in an identical manner. In this case two further vertically extending ducts 3, 4 are located on the other narrow side.

In order to clarify the aforementioned, FIG. 7 has been added. Otherwise, this figure does not show the matter proposed here, since the region having a plate 6 finishing off the stack 1 of plate pairs 10 and fins 2 is not illustrated in FIG. 7. The ducts may be two inflow ducts 3 and two outflow ducts 4. FIG. 7 shows a view into the interior of the uppermost plate pair 10. Ribs 9 are located in the plate pairs 10. The ribs 9 are smaller than the interior of the plate pairs. There are two peripheral ducts 90 which extend in the longitudinal direction of the plates. The one peripheral duct 90 is an inflow-side peripheral duct in which a concurrent flow is present. The other peripheral duct 90 is an outflow-side peripheral duct 90 in which a diverging flow toward the two outflow ducts 4 is present. This design leads to an effective counterflow in relation to another medium, as is to be indicated by the arrows, on account of which the efficiency of heat exchange is improved as a spin-off.

However, it may in contrast also be assumed that the two ducts 3 and 4, shown in FIGS. 1 to 6, are the only vertical ducts of the heat exchanger for the mentioned medium, wherein the one duct would be an inflow duct 3 and the other duct would be an outflow duct 4. The arrows in FIG. 2 are intended to indicate this. In the longitudinal direction of the heat exchanger, the medium covers an outward and an inward path. In this case, a throughflow of the heat exchanger would be present in the crossflow.

The ducts 3, 4 are formed from openings 5 in the plates 10a, 10b, having moldings 51 which extend around the opening peripheries 50 of said openings 5.

Visible are also the already mentioned fins 2 which are disposed between the plate pairs 10. Another medium, which exchanges heat with the first mentioned medium, flows through the fins 2. The other medium may be hot air (or an exhaust emission) which is to be cooled.

The temperature differences for operational reasons between the air and the coolant are enormous and stress the brazed heat exchanger to the point of material fractures which typically lead to the breakdown of the heat exchanger.

In order to improve the resilience of the heat exchanger to such loadings, the measure shown in FIGS. 1 and 2 has proven particularly effective.

As shown by the mentioned figures, this measure is thermally decoupling elements 7 which are separately inserted as an individual part and which are incorporated into the vertical duct formation 3, 4. As can be seen, each duct 3, 4, has been assigned a separate element 7. There thus may be either two or four such elements 7 per heat exchanger.

The term “thermally decoupling” used here refers exclusively to thermal influences due to operational reasons on the heat exchanger and/or on its decoupling, not to the brazing-technological production of said heat exchanger, which likewise takes place under thermal influences, as is known. With regard to the brazing-technological production, reference may be made to the prior art, such that no further explanations are required in this respect.

The insertion of the elements 7 takes place between the uppermost plate lying on the stack, in the exemplary embodiment a cover plate 6, and the upper plate of the first plate pair 10. More specifically, the elements 7 are inserted between the uppermost plate 6 and the moldings 51 which extend around the opening peripheries of the uppermost plate 10a of the first plate pair 10. In respect of their extent, the elements 7 are also only slightly larger than the moldings 51, as shown by FIGS. 1 and 2. The contour of the moldings approximately corresponds to the contour of the element 7, which is to mean that the contours are similar with regard to shape and size. However, the thicknesses vary.

The particular effectiveness of this preferred embodiment may lie in that the elements 7 are provided with at least one fold 73 which, after the production or configuration thereof, leads to a doubling. A second fold (not shown) at the opposite end would lead to a trebling of the thickness. It should also be identifiable that the elements 7 are initially punched from a sheet metal having two openings. After production of the fold 73 (bending by 180°), the two openings lie approximately on top of one another. As can also be seen, the upper opening of the elements 7 is slightly larger or designed in a somewhat different manner than the lower opening. Said opening provides a transition from (in the exemplary embodiment) approximately flat-oval openings and/or approximately flat-oval moldings 51 of the opening peripheries to approximately round apertures 60 in the uppermost plate 6. Accordingly, round connectors for the coolant are located in the round apertures 60 of the uppermost plate 6 (FIG. 4).

On account of the elongate or flat-oval openings in the plates 10a, 10b there is inter alia also an advantageous flexibility in relation to the arrangement of the round connectors. The arrangement of the connectors depends on the circumstances of the installation space. This flexibility is not limited by the provision of the elements 7, since the possibility for modifying the design of the elements 7 exists, that is to say for designing said elements 7 so as to be different, as can be seen from FIG. 2.

In other exemplary embodiments (not shown), the elements 7 are all configured so as to be identical, which is definitely more cost effective in relation to their production.

In the exemplary embodiment according to FIGS. 3 and 4, the fold 73 and/or the doubling of the element 7 produced by the fold 73 has been dispensed with. The element 7 has furthermore been configured in one part for two adjacent ducts 3 and 4. It is also significantly thicker than in the exemplary embodiment according to FIGS. 1 and 2. As can furthermore be seen from FIG. 4, the element 7 has at least in part been provided with a peripheral chamfer 77. The brazing surface can be somewhat enlarged in this manner, but the main objective is presumably to improve the desired positioning of the fin 2, which lies below the cover plate 6, in the course of the pre-assembly of the heat exchanger.

In contrast to what has been described above, in the exemplary embodiment according to FIGS. 5 and 6 a further plate 11, which is substantially thinner than the cover plate 6, has been disposed below the cover plate 6. The elements 7, likewise in contrast to what has been mentioned above, have been configured in an integral manner with the thinner further plate 11, that is to say as one piece. In conformance with FIGS. 1 and 2, an element 7 has also here been assigned to each duct 3, 4. A further conformance with the embodiments described above consists in that a doubling is also achieved with these elements 7 by means of a fold 73. On account of the one-piece design, initially the further plate 11, having corresponding projections and the two openings from which the elements 7 have to be configured by producing the fold 73, will have to be cut out, wherein the projections are laid inward and wherein the two openings are brought into congruence. By means of FIG. 6, this procedure can be particularly clearly traced. The dimension of the further plate 11, with respect to length and width, otherwise corresponds to that of the cover plate 6.

FIG. 8 shows that the heat exchanger is disposed in a housing 8, on the one side of which the other medium flows in, flows through the fins 2 of the heat exchanger, and flows out of the housing 8 on the opposite other side of said housing 8, to which end the housing displays corresponding inflow and outflow openings 81, 82.

The heat exchanger is sealed toward the housing 8, in order to suppress bypasses for the other medium.

The medium flowing through the plate pairs 10 and the medium flowing through the fins 2 run either approximately in the direction of counterflow or in the direction of crossflow.

The heat exchanger is inserted into the housing 8 through an insertion opening 83 and, with a projecting, encircling periphery of the finishing-off plate 6, is preferably welded into place on a periphery of the insertion opening 83.

Claims

1. A brazed heat exchanger comprising: a stack of plate pairs;fins that are disposed between the plate pairs;ducts that vertically extend through the stack of plate pairs, the ducts are formed from openings in the plate pairs and moldings that are connected to one another and extend around opening peripheries of the openings, the ducts configured to convey in or convey out a first medium that flows though the plate pairs and that exchanges heat with a second medium that flows through the fins;a plate having apertures that correspond to the openings in the plate pairs, the plate finishes off the stack of plate pairs; anda thermally decoupling element is disposed between the plate and the stack of plate pairs, the thermally decoupling element is incorporated into a formation of at least one of the ducts and a contour of the thermally decoupling element approximately corresponds to a contour of the moldings.

2. The brazed heat exchanger according to claim 1, wherein the thermally decoupling element is disposed around the apertures of the plate and toward an adjacent molding.

3. The brazed heat exchanger according to claim 1, wherein the thermally decoupling element includes at least two openings and a bend that is configured in such a manner that, after production of the bend, the two openings form a single opening which communicates with a corresponding aperture of the plate.

4. The brazed heat exchanger according to claim 1, wherein each aperture in the plate is assigned a separately inserted thermally decoupling element.

5. The brazed heat exchanger according to claim 1, wherein the thermally decoupling element is configured in one part and with two openings that are disposed beside one another for two adjacent ducts.

6. The brazed heat exchanger according to claim 5, wherein the thermally decoupling element is substantially planar.

7. The brazed heat exchanger according to claim 1, wherein at least one support foot is disposed on the thermally decoupling element.

8. The brazed heat exchanger according to claim 7, wherein positioning aids are disposed on the thermally decoupling element.

9. The brazed heat exchanger according to claim 1, wherein the heat exchanger is disposed in a housing having a first side, a second side opposite the first side, and an end, wherein the second medium flows in the first side, through the fins, and out from the housing on the second side of the housing.

10. The brazed heat exchanger according to claim 9, wherein the end of the housing includes inflow and outflow openings.

11. The brazed heat exchanger according to claim 9, wherein the heat exchanger is sealed toward the housing in order to suppress bypasses for the second medium.

12. The brazed heat exchanger according to claim 1, wherein the first medium flowing through the plate pairs and the second medium flowing through the fins lie approximately in the direction of counterflow.

13. The brazed heat exchange according to claim 1, wherein the first medium flowing through the plate pairs and the second medium flowing through the fins lie approximately in the direction of crossflow.

14. The brazed heat exchanger according to claim 1, wherein the heat exchanger is inserted into a housing through an insertion opening and, with a projecting, encircling periphery of the plate welded into place on a periphery of the insertion opening.

15. A brazed heat exchanger comprising: a stack of plate pairs;fins that are disposed between the plate pairs;ducts that vertically extend through the stack of plate pairs, the ducts are formed from openings in the plate pairs and moldings that are connected to one another and extend around opening peripheries of the openings, the ducts configured to convey in or convey out a first medium that flows though the plate pairs and that exchanges heat with a second medium that flows through the fins;a first plate having apertures that correspond to the openings in the plate pairs, the first plate finishes off the stack of plate pairs; anda second plate disposed between the first plate and the stack of plate pairs; anda thermally decoupling element that is integrally configured with the second plate and is incorporated into the formation of at least one of the ducts,wherein the thermally decoupling element lies against the second plate and is connected to the second plate by way of a fold.

16. The brazed heat exchanger of claim 15, wherein the thermally decoupling element displays a contour that approximately corresponds to a contour of the adjacent molding.

17. The brazed heat exchanger of claim 15, wherein the thermally decoupling element in the course of its production, initially protrudes beyond a circumference of the second plate, wherein the thermally decoupling element is subsequently bent inward and is laid against the second plate.

18. The brazed heat exchanger of claim 15, wherein at least one support foot is disposed on the thermally decoupling element.

19. The brazed heat exchanger of claim 18, wherein positioning aids are disposed on the thermally decoupling element.

20. The brazed heat exchanger of claim 15, wherein the heat exchanger is disposed in a housing having a first side, a second side opposite the first side, and an end, wherein the second medium flows in the first side, through the fins, and out from the housing on the second side of the housing.