US20190242658A1

US20190242658A1 - Heat exchanger

Info

Publication number: US20190242658A1
Application number: US15/748,642
Authority: US
Inventors: Thomas SCHIEHLEN; Holger Schroth
Original assignee: Mahle International GmbH
Current assignee: Mahle International GmbH
Priority date: 2015-08-06
Filing date: 2016-08-02
Publication date: 2019-08-08
Also published as: EP3332206A1; WO2017021416A1; CN107850402A; EP3332206B1; DE102015215053A1

Abstract

A heat exchanger may include a plurality of tubes and a plurality of corrugated fins arranged between the plurality of tubes. The plurality of corrugated fins may have straight flanks and may define a plurality of corrugation troughs and a plurality of corrugation peaks each having a curve. According to one example, the curve of a corrugation peak may have a curved first segment and a linear second segment. According to another example, the curve of a corrugation peak may have a curved first segment and a curved second segment that is curved in the same direction as the curved first segment. A laminated adhesive layer may be disposed on an outer side of the plurality of tubes.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to International Application No. PCT/EP2016/068452 filed on Aug. 2, 2016, and to German Application No. DE 10 2015 215 053.4 filed on Aug. 6, 2015, the contents of each of which are hereby incorporated by reference in their entirety.

TECHNICAL FIELD

The present invention relates to a heat exchanger comprising tubes and corrugated fins arranged therebetween, which corrugated fins have straight flanks and have corrugation peaks and corrugation troughs each having a curve.

BACKGROUND

From DE 10 2006 035 209 A1 a generic heat exchanger comprising tubes and corrugated fins arranged therebetween is known, which have corrugation peaks and corrugation troughs and flanks arranged therebetween, wherein the flanks are equipped with cuts exposed from their planes. The flanks continue here via a bending edge into the corrugation peaks or respectively corrugation troughs, wherein these bending edges are configured in a weakened manner, so that the springback occurring on bending is reduced. Hereby, a heat exchange having improved efficiency is to be able to be provided.
From DE 201 18 511 U1 a heat exchanger network and a heat exchanger equipped therewith is known, wherein the heat exchanger network has a plurality of flat tubes, and plates, arranged between the flat tubes, in heat-conducting contact therewith, and wherein the heat-conducting contact is produced solely through reciprocal bracing of the flat tubes and plates. The plates are elastically deformable here in the direction of the bracing, whereby an installation effort is to be reduced.
In order to be able to achieve as high a performance as possible in heat exchangers, corrugated fins are inserted between individual tubes of such heat exchangers in a known manner, which corrugated fins are usually soldered to the tubes for improved heat transfer. Alternatively to a soldering, a bonded connection is known for fixing the corrugated fins to the tubes, wherein hitherto the adhesives used for this were loaded for example with heat-conducting particles of boron nitride or aluminium, in order to be able to improve the thermal conductivity of the adhesive. However, such heat-conducting particles have a disadvantageous influence on the price of the adhesive and its processing. It is likewise known to glue in a soldered network, wherein for this, however, two production methods must be combined, which likewise has a negative influence on the costs.
It is disadvantageous in the solder structures known from the prior art that these are designed to compensate for manufacturing tolerances which occur during assembly, via the tube geometry. However, this is not possible in a purely bonded heat exchanger and, for example with an extruded tube geometry. For this reason, for example corrugated fins are used, which can undertake such a compensation function.
The present invention is concerned with the problem of indicating for a heat exchanger of the generic type an improved or at least an alternative embodiment, which in particular overcomes the disadvantages known from the prior art.
This problem is solved according to the invention by the subject of the independent claim(s). Advantageous embodiments are the subject of the dependent claims.

SUMMARY

The present invention is based on the general idea of being able, on the one hand, of creating a heat exchanger which can be bonded, and on the other hand, however, of equipping it at a comparatively favourable cost and with corresponding tolerance compensation possibilities and with a high heat exchanger performance. The heat exchanger according to the invention has here, in a known manner, tubes and corrugated fins, arranged therebetween, with straight flanks and corrugation troughs and corrugation peaks having respectively a curve. The curve of a corrugation peak can be configured here alternatively in two embodiments according to the invention. In the two alternatives, the corrugation peaks are optimized to the effect that a minimum abutment is enforced by a spring effect, whereby an improved heat transmission capability and thereby a minimum system performance can be guaranteed. The shape of the corrugation peak of such a corrugated fin according to the invention is based here in bionic form on the shape of a human foot. Here, it is particularly advantageous that a pressure-stable fin or respectively flank of the corrugated fin is produced, which prevents a buckling under the application of pressure. Basically, the first alternative embodiment of a curve of a corrugation peak has a curved first segment and a linear second segment, wherein the second segment is twice as long as the first segment and wherein the two segments have an opposite slope of between 0.1 to 0.5%. This means that the curved first segment has a positive slope of +0.1 to +0.5%, whilst the linear second segment has a negative slope of −0.1 to −0.5%. The slope of the curved first segment is determined here between its start and end point. Through such a curve of the corrugation peaks of the corrugated fin, on the one hand a required tolerance compensation can be achieved, and on the other hand a flat abutting of the corrugated fin against the tubes, whereby a high thermal transfer and thereby a high performance of the heat exchanger can be achieved. The corrugation troughs are configured here of course in accordance with the corrugation peaks, only in reverse form, i.e. for example by a first and second segment standing upside down. The corrugation peak can therefore correspond to a mirrored corrugation trough or vice versa.
In the second alternative embodiment of the curve of a corrugation peak, the latter likewise has a curved first and a curved second segment which, however, in this case are equally long, wherein the first segment again continues via a maximum point into the second segment and wherein in the case of unloaded corrugated fins, a tolerance distance a remains between two adjacent corrugation peaks, which is dimensioned in such a way that it is pressed to zero in the state of installation in the heat exchanger, and thereby the corrugation peaks lie in contact with each other. The two segments are arranged here in mirror image to one another, in so far as the mirror axis runs through the maximum point. The horizontal tolerance distance a between two corrugation peaks or respectively between two corrugation troughs can therefore determine in a preset manner a possible vertical spring travel, because after exploiting this spring travel, two adjacent corrugation peaks or two corrugation troughs contact one another and thereby an extremely stable arch construction results. Hereby, on the one hand, a buckling of the individual flanks or respectively corrugated fins is prevented, and on the other hand a sufficient pressure-stable surface is created, in order to displace excess adhesive out from the gap between the corrugation peak or respectively the corrugation trough and the tube. This is important in particular for an optimum thermal transfer. The remaining adhesive layer is thereby reduced to a minimum with, at the same time, the guarantee of a freedom from bubbles.
In general, the following advantages can be achieved with the heat exchanger according to the invention:
compensation of manufacturing tolerances, which must be compensated in the assembly of the corrugated fin and tube system, whereby extremely thin adhesive layer thicknesses are able to be realized and thereby the performance of the heat exchanger can be increased,
enlargement of a contact surface of the corrugated fin on the tube and thereby an improved thermal transfer,
a spring effect through the compensation of the manufacturing tolerances in the assembly and producing of a uniform layer of adhesive in an exactly predefined region,
a pressure-stability of the corrugated fin without the risk of buckling, with equal material thickness,
lower costs with regard to energy and resources, and the possibility of connecting to one another corrugated fins and tubes of different materials, because the adhesive layer is electrically insulating and thereby prevents a contact corrosion,
considerable CO₂saving in production, through the omission of soldering furnaces and the energy required for this.
In a further advantageous embodiment of the solution according to the invention, an opposite slope of the first and of the second segment is approximately 0.3-0.4%. Hereby, a comparatively flat corrugation peak or respectively a comparatively flat corrugation trough can be created, which on the one hand enables a flat and thereby good heat-transferring connection to the tube, and on the other hand enables the desired tolerance compensation.
In a further advantageous embodiment of the solution according to the invention, an adhesive layer is applied on an outer side of the tubes, in particular by laminating: By means of such a laminating, the adhesive layer can thereby be applied in particular in the manner of an adhesive foil or an adhesive film, whereby the applying of the adhesive layer is not only economical, but in addition also of extremely high quality.
In a further advantageous embodiment of the solution according to the invention, the corrugated fins are formed from a material having good thermal conductivity, preferably aluminium, copper etc. Here, a material combination can also be considered, because the adhesive layer has an insulating effect and thereby a contact corrosion is prevented.
Expediently, the heat exchanger is configured as an evaporator, as an engine cooler, as a condenser, as a charge air cooler, as a chiller, as an oil cooler, as a heating body or as a PTC auxiliary heater. This non-exclusive list already suggests what a diverse field of use presents itself for the corrugated fins according to the invention, and also for the heat exchanger according to the invention.
Further important features and advantages of the invention will emerge from the subclaims, from the drawings and from the associated figure description with the aid of the drawings.
It shall be understood that the features mentioned above and to be explained further below are able to be used not only in the respectively indicated combination, but also in other combinations or in isolation, without departing from the scope of the present invention.
Preferred example embodiments of the invention are represented in the drawings and are further explained in the following description, wherein the same reference numbers refer to identical or similar or functionally identical components.

BRIEF DESCRIPTION OF THE DRAWINGS

There are shown here, respectively diagrammatically

FIG. 1 a sectional illustration through a heat exchanger according to the invention with corrugated fins according to a first alternative embodiment,

FIG. 2 a detail illustration of the corrugated fin according to the first alternative embodiment,

FIG. 3 an illustration as in FIG. 1, but with corrugated fins according to a second alternative embodiment,

FIG. 4 a detail illustration of the corrugated fins according to the second alternative embodiment.

DETAILED DESCRIPTION

According to FIGS. 1 and 3, a heat exchanger 1 according to the invention, which can be configured for example as an evaporator, as an engine cooler, as a condenser, as a charge air cooler, as a chiller, as an oil cooler, as a heating body or as a PTC auxiliary heater, has tubes 2 and corrugated fins 3 arranged therebetween, with straight flanks 4 and corrugation troughs 6 and corrugation peaks 7 respectively having a curve 5 (cf. also FIGS. 2 and 4). The corrugated fins 3 are bonded to the tubes 2 here via an adhesive layer 8. In order to now be able to achieve as optimum a thermal transfer as possible between the corrugated fins 3 and the tubes 2 and, at the same time, to achieve a possible compensation of manufacturing tolerances, the curve 5 of a corrugation peak 6 is configured in accordance with the invention according to two alternative embodiments:
In the first alternative embodiment of the curve 5 according to the invention, the latter has a curved first segment 9 and a linear second segment 10, wherein the linear second segment 10 is twice as long as the first segment 9. The length specified for this refers here to an extent along a centre axis 12. The curved first segment 9 has here a slope of 0.1-0.5%, preferably between +0.3 and +0.4%, whilst the linear second segment 10 has an opposite slope hereto of −0.1 to −0.5%, preferably of −0.3 to −0.4%. The height of the curve 5 up to the transition into the respective flanks 4 is designated here according to FIGS. 2 and 4 by m. The slope of the curved first segment 9 is determined here between its start and end point, wherein S=m/L applies for the slope.
Observing the second alternative embodiment of the corrugated fin 3 according to the invention, its curve 5 of a corrugation peak 6 (cf. FIG. 4) has a curved first segment 9 and a second segment 10 curved in the same direction, which have the same length L (along the centre axis 12) and accordingly are configured to be of equal length. In the case of an unloaded corrugated fin 3, a tolerance distance a remains between two adjacent corrugation peaks 4, which tolerance distance is dimensioned in such a way that it goes to zero in the state of installation in the heat exchanger 1 and thereby the corrugation peaks 6 lie in contact with each other.
The difference between the corrugation peaks 6 and the corrugation troughs 7 can be seen merely in a mirroring with respect to the centre axis 12, so that the corrugation peaks 6 correspond to the corrugation troughs 7.
The adhesive layer 8 is applied here on the outer side of the tubes 2, for example by laminating, whereby such an adhesive layer 8, for example in the manner of an adhesive film or an adhesive foil, can be applied not only at a favourable cost, but also with a small layer thickness and in a reliable manner. In the region of their corrugation peaks 6 and their corrugation troughs 7, the individual corrugated fins 3 are bonded here to the respectively adjacent tubes, wherein the corrugated fins 3 preferably lie flat against the tubes 2 in the region of their corrugation peaks 6 and of their corrugation troughs 7, and thereby enable a good thermal transfer.
The corrugated fins 3 according to the invention are formed here preferably from aluminium and thereby from a material having good thermal conductivity. Purely theoretically, by a bonding of the corrugated fins 3 to the tubes 2 a combination of different materials is also conceivable, so that the corrugated fins 3 can be formed from a different material to the tubes 2, without the risk of a contact corrosion existing.
With the corrugated fins 3 shaped according to the invention, manufacturing tolerances which occur in the assembly of the system 3 and tube 2, can be compensated particularly easily, whereby air inclusions and higher adhesive layer thicknesses, which have an insulating effect and thereby cause a reduced performance of the bonded heat exchanger 1, can be prevented. Through the bionic embodiment of the curves 5, an increase to the contact surface on the tube 2 can also be achieved, whereby a likewise improved thermal transfer is able to be achieved.
The embodiment of the corrugated fins 3 illustrated according to FIG. 2 can of course also be configured symmetrically here and not asymmetrically as in the illustrated example.
The spring effect which is able to be achieved with the corrugated fin 3 according to the invention therefore allows manufacturing tolerances to be compensated comparatively simply, even in the case of small layer thicknesses. Through the moving of the individual corrugation peaks 6 or respectively corrugation troughs 7 against one another, in the corrugated fin 3 according to FIGS. 3 and 4 in addition a particularly stable system can be created, in which an undesired buckling of the flanks 4 can be reliably prevented. Through the bonding of the heat exchanger 1 according to the invention, moreover, considerable cost advantages can be achieved, in particular as regards the resources which are used and as regards the energy which is used, in particular with regard to a soldering process, whereby a CO₂balance can be distinctly improved.
Such a heat exchanger 1 can be used for example in an internal combustion engine 11.

Claims

1. A heat exchanger, comprising:

a plurality of tubes and a plurality of corrugated fins arranged therebetween, the plurality of corrugated fins having straight flanks and defining a plurality of corrugation troughs and a plurality of corrugation peaks each having a curve, wherein:

the curve of at least one corrugation peak has a curved first segment and a linear second segment, wherein the second segment is at least twice as long as the first segment, and the first segment and the second segment have an opposite slope of 0.1 to 0.5; or

the curve of at least one corrugation peak has a curved first segment and an equally long second segment curved in a direction the same as the first segment, wherein a tolerance distance is provided between two adjacent corrugation peaks when the plurality of corrugated fins are unloaded, and upon being loaded the tolerance distance reduces to zero in in an installed state such that the plurality of corrugation peaks lie in contact with one another; and

a laminated adhesive layer disposed on an outer side of the plurality of tubes.

2. The heat exchanger according to claim 1, wherein the plurality of corrugation troughs correspond to a reversed configuration of the at least one corrugation peak.

3. The heat exchanger according to claim 1, wherein the plurality of corrugated fins are bonded to the plurality of tubes in a region of the plurality of corrugation peaks and the plurality of corrugation troughs.

4. The heat exchanger according to claim 1, wherein the curve of the at least one corrugation peak has the curved first segment and the linear second segment, and wherein the opposite slope of the first segment and the second segment is 0.3-0.4.

5. The heat exchanger according to claim 1, wherein the heat exchanger is configured as an evaporator, as an engine cooler, as a condenser, as a charge air cooler, as a chiller, as an oil cooler, as a heating body or as a PTC auxiliary heater.

6. The heat exchanger according to claim 1, wherein the plurality of corrugated fins are composed of an aluminium material.

7. The heat exchanger according to claim 1, wherein the plurality of corrugated fins lie flat against the plurality of tubes in a region of the plurality of corrugation peaks and the plurality of corrugation troughs.

8. An internal combustion engine, comprising: a heat exchanger including:

a plurality of tubes;

a plurality of corrugated fins arranged between the plurality of tubes, the plurality of corrugated fins having straight flanks and defining a plurality of corrugation troughs and a plurality of corrugation peaks;

a laminated adhesive layer disposed on an outer side of the plurality of tubes; and

wherein the plurality of corrugated peaks and the plurality of corrugated troughs each have a curve, and wherein:

the curve of at least one corrugation peak has a curved first segment and a linear second segment, wherein the linear second segment is at least twice as long as the curved first segment, and the curved first segment and the linear second segment have an opposite slope of 0.1 to 0.5; or

the curve of at least one corrugation peak has a curved first segment and an equally long second segment curved in a direction the same as the curved first segment, wherein a tolerance distance is provided between two adjacent corrugation peaks when the plurality of corrugated fins are unloaded, and upon being loaded the tolerance distance reduces to zero when the heat exchanger is in an installed state such that the plurality of corrugation peaks lie in contact with one another.

9. The internal combustion engine according to claim 8, wherein the plurality of corrugated fins are bonded to the plurality of tubes in a region of the plurality of corrugation peaks and the plurality of corrugation troughs.

10. The internal combustion engine according to claim 8, wherein the curve has the curved first segment and the linear second segment, and wherein the opposite slope of the first segment and the second segment is 0.3-0.4.

11. The internal combustion engine according to claim 8, wherein the heat exchanger is configured as an evaporator, as an engine cooler, as a condenser, as a charge air cooler, as a chiller, as an oil cooler, as a heating body or as a PTC auxiliary heater.

12. The internal combustion engine according to claim 8, wherein the plurality of corrugated fins are composed of an aluminium material.

13. The internal combustion engine according to claim 8, wherein the plurality of corrugated fins lie flat against the plurality of tubes in a region of the plurality of corrugation peaks and the plurality of corrugation troughs.

14. The internal combustion engine according to claim 8, wherein the plurality of corrugation troughs correspond to a reversed configuration of the at least one corrugation peak.

15. The internal combustion engine according to claim 8, wherein the curve of each one of the plurality of corrugation peaks has the curved first segment and the curved second segment, and wherein the plurality of corrugated fins are composed of an aluminium material.

16. The heat exchanger according to claim 1, wherein the curve of each one of the plurality of corrugation peaks has the curved first segment and the linear second segment, and wherein the plurality of corrugated fins are coupled to the plurality of tubes in a region of at least one of the plurality of corrugation peaks and the plurality of corrugation troughs.

17. The heat exchanger according to claim 1, wherein the curve of each one of the plurality of corrugation peaks has the curved first segment and the curved second segment, and wherein the plurality of corrugated fins are coupled to the plurality of tubes in a region of at least one of the plurality of corrugation peaks and the plurality of corrugation troughs.

18. The heat exchanger according to claim 2, wherein the plurality of corrugated fins are bonded to the plurality of tubes in a region of the plurality of corrugation peaks and the plurality of corrugation troughs.

19. The heat exchanger according to claim 2, wherein the curve of the at least one corrugated peak has the curved first segment and the linear second segment, and wherein the opposite slope of the first segment and the second segment is 0.3-0.4.

20. A heat exchanger, comprising:

a plurality of tubes;

a laminated adhesive layer disposed on an outer side of the plurality of tubes;

the curve of each corrugation peak of the plurality of corrugation peaks has a curved first segment and a linear second segment, wherein the linear second segment is at least twice as long as the curved first segment, and the curved first segment and the linear second segment have an opposite slope of 0.1 to 0.5; or

the curve of each corrugation peak of the plurality of corrugation peaks has a curved first segment and an equally long second segment curved in a direction the same as the curved first segment, wherein a tolerance distance is provided between two adjacent corrugation peaks when the plurality of corrugated fins are unloaded, and upon being loaded the tolerance distance reduces to zero in an installed state such that the plurality of corrugation peaks lie in contact with one another; and

wherein the plurality of corrugated fins are secured via a bonded connection to the plurality of tubes in a region of the plurality of corrugation peaks and the plurality of corrugation troughs.