Corrugated fin and method for producing it

A corrugated fin, in particular for a heat exchanger, having a substantially corrugated design, having a plurality of fin surfaces, wherein adjoining fin surfaces are connected to one another by means of a fin arch in such a way that a medium can flow through an intermediate space between adjoining fin surfaces, wherein the fin surfaces are arranged at an angle with respect to one another perpendicularly with respect to a throughflow direction for the medium, wherein the fin surface has at least one bulge which protrudes out of the plane of the fin surface, wherein the extent of the bulge in a direction perpendicularly with respect to the air throughflow direction is smaller than the extent of the fin surface in said direction.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a corrugated fin and to a method for the production thereof and to a heat exchanger having such a corrugated fin.

Description of the Background Art

Corrugated fins are known in the conventional art for use in heat exchangers to improve the heat transfer. In this regard, corrugated fins are known, for example, for the air-side heat transfer, which are arranged substantially wave-shaped or zigzag-shaped folded back and forth between lateral sides of tubes, so that a medium can flow in the intermediate spaces of the fin. In this regard, corrugated fins have become known in which adjacent fin surfaces, connected to one another by means of a fin arch, are parallel to one another or are arranged at an acute angle to one another. In this regard, the fin arch can be an arch which is continuous in the flow direction of the medium and lies against a tube side surface or it can be formed as an offset arch, which is divided into intervals and is offset.

Such corrugated fins have become known, for example, from DE 602 03 721 T2, which corresponds to U.S. Pat. No. 6,546,774. In these corrugated fins with parallel fin surfaces, the possibility of introducing additional turbulence-generating elements in the side surfaces is limited, because the corrugated rollers would again destroy these during the rolling of the parallel side surfaces.

DE 10 2009 015 849 A1, which corresponds to U.S. Pat. No. 8,516,699, discloses a corrugated fin in which the side surfaces have dimples which extend up to the fin arch and deform it to form a wavy contour.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide a corrugated fin and a heat exchanger having a corrugated fin, both of which are improved compared with the conventional art and are nevertheless more simple to produce.

DE 10 2008 015 064 A1, which is incorporated herein by reference, discloses a corrugated fin with fin surfaces which are oriented perpendicular to one another and are deformed inwardly by deformations.

An exemplary embodiment provides a corrugated fin, particularly for a heat exchanger, with a substantially corrugated design, having a plurality of fin surfaces, whereby adjacent fin surfaces are connected to one another by means of a fin arch in such a way that a medium can flow through an intermediate space between adjacent fin surfaces, whereby the fin surfaces are arranged at an angle with respect to one another perpendicular to a throughflow direction for the medium, whereby a fin surface has at least one bulge which protrudes out of the plane of the fin surface, whereby the extent of the bulge in a direction perpendicular to the air throughflow direction is smaller than the extent of the fin surface in this direction. This means that the bulge in the direction perpendicular to the air throughflow direction does not protrude relative to a vertical line, defined by the end regions of the fin surface. The bulge therefore does not enter a spatial region which is defined by the fin arch and the space, defined for this purpose perpendicular to the air throughflow direction, or surface region.

In an embodiment, the bulge can be spaced apart from an end region of the fin surface, which is adjacent to a fin arch, or also from both end regions of the fin surface, said regions each adjacent to a fin arch. This achieves that the bulge does not enter a spatial region, defined by the fin arch and the space, defined for this purpose perpendicular to the air throughflow direction, or the surface region.

A plurality of bulges can be formed and arranged per fin surface, whereby the bulges of a fin surface protrude toward one side with respect to the plane of the fin surface. This promotes the transfer of heat between the fin and the flowing medium such as, for example, air.

A plurality of bulges can be formed and arranged per fin surface, whereby a first portion of bulges of a fin surface protrude toward a first side and a second portion of bulges toward a second side with respect to the plane of the fin surface. This also promotes the transfer of heat between the fin and a flowing medium.

The first portion of bulges can be formed spaced apart from the second portion of bulges or these touch one another or merge into one another. If the bulges are spaced apart, surface regions of the fin surface that separate the individual bulges from one another, are arranged between bulges. If the bulges merge into each other or touch each other, there are either no surface regions of the fin surface or only a boundary between the individual bulges.

The bulges can have a round or elongated and/or oval contour.

Bulges with an elongated and/or oval contour can have a longitudinal axis, which is arranged at an angle to the throughflow direction.

The angle for all bulges can be the same. This means that the orientation of the bulges in air throughflow direction of at least one fin surface or all fin surfaces is the same.

In an embodiment, the angle for adjacent bulges can be different. Thus, it can be achieved that alternating bulges have different angles. It can be advantageous in this case that each second bulge has the same angle.

In an embodiment, the angle for adjacent bulges can be symmetric relative to a vertical line when viewed in regard to the air direction. This means that, for example, an angle of the first bulge is 45° and the angle of the adjacent bulge is 135°. The angles of the two bulges then add up to 180°.

The bulge can be formed as a corrugated embossing on one or on opposite fin surfaces.

The corrugated embossings on opposite fin surfaces can be formed projecting in the same direction.

The corrugated embossing can extend along the fin surface in the flow direction.

In an embodiment, the corrugated embossing can modulate the fin surface perpendicular to the flow direction.

Also, an arcuate embossing, which surrounds the corrugated embossing above and/or below, can be provided above and/or below the corrugated embossing.

The arcuate embossings can form a band running parallel to the corrugated embossing.

Further, the bulge depth of the corrugated embossings and/or the arcuate embossings can be formed constant or variable over the height of the fin.

In an embodiment, the bulge out of the trapezoidal fin surface in the region of the trapezoid base can be smaller than a bulge in the region of the trapezoid top.

In an embodiment, a bulge into the trapezoidal fin surface in the region of the trapezoid base can be greater than a bulge in the region of the trapezoid top.

The bulge height can be between 60% and 95% of the fin height H, preferably 80%.

Further, a counter-bulge can be formed in at least one or in each trough and/or peak of the corrugated embossing.

In an embodiment, an object a heat exchanger is provided having fluid channels with side surfaces of the fluid channels, with spatial regions between adjacent side surfaces, whereby a top corrugated fin is arranged between adjacent side surfaces such that it lies against one of the side surfaces by means of opposite fin arches.

In an embodiment, a method is provided for producing a corrugated fin, in which bulges proceeding from a band are embossed in the band with a set of rollers and then the flat band is shaped into a corrugated fin by means of a set of rollers.

DETAILED DESCRIPTION

FIG. 1shows a tube1, which is designed as a fluid channel of a heat exchanger, whereby the tube has two wide side surfaces2,3and two narrow side surfaces4,5, which lie opposite to each other and define an interior space6, which is suitable for throughflow for a medium. A corrugated fin7, formed by fin surfaces8,9, each of which is connected together by fin arches10, is arranged in the interior of tube1. In this case, fin arches10each lie against a side surface2,3of the tube. Fin arches10can preferably be soldered to the side surfaces. They can also be applied merely mechanically.

In a further exemplary embodiment, corrugated fin7can also be arranged between two tubes, whereby fin arches10are each in contact with a side surface of an adjacent tube or connected thereto.

FIG. 2shows a section of a corrugated fin11in section, whereby the corrugated fin has fin surfaces12and fin arches13connecting fin surfaces12, whereby fin surfaces12are inclined in a plane perpendicular to the air flow direction. In this case, the air flow direction in the case of corrugated fin11according toFIG. 2is substantially perpendicular to the plane of the sheet ofFIG. 2. Bulges14, which bulge out of the plane of fin surface12, are provided in fin surfaces12. As can be seen, two adjacent fin surfaces12together with fin arch13form an approximately trapezoidal spatial region, which is available for throughflow of a medium. In this regard, bulges14can protrude into this spatial region proceeding from the plane of fin surface12.

In the exemplary embodiment ofFIG. 2, fin arch13has a width B, the height of the fin from a fin arch to an opposite fin arch is H, the height of the projection in the plane of the side surface is designated by A, and the distance of two fin arches corresponds to twice the value of L, whereby inFIG. 2only the value of L is shown as the distance of two opposite fin arches, in the plane perpendicular to the air throughflow direction. The values for a fin are, for example, L=2 to 3 mm, preferably 2.5 mm, H=6 to 8 mm, preferably 7 mm, A=4 to 7 mm, preferably 5.4 mm, B=0.8 to 2 mm, preferably 1.3 mm, and the fin thickness is approximately 0.08 to 0.15 mm, preferably 0.12 mm.

FIG. 3shows an arrangement of a fin20in roller gap21of a rolling machine with two rollers22,23, whereby it can be seen that fin arch24is connected to fin surface25, which is provided with a projection26. It can also be seen that the substantially corrugated contour of the fin in a plane perpendicular to the throughflow direction is already created by the rolling.

InFIG. 4, a further rolling machine30can be seen with rollers31and32, which have regions33and34interlocking comb-like, whereby corrugated fin35is taken up with its fin surfaces36in this roller setup. In this case, fin arches37are arranged in the head region of comb-like elements33,34in order to form the structure of the corrugated fin, whereby fin surfaces36with bulges38are arranged between the comb-like elements, whereby the bulges of comb-like elements33,34are spaced apart, so that they are not damaged or destroyed while the fin is being formed.

FIG. 5shows a corrugated fin40with fin arches41and fin surfaces42and bulges43of fin surfaces42. It can be seen in this case that spatial region44defined by the width of fin arch41is kept clear by bulges43. The detail inFIG. 5ashows this once again in an enlargement. Here, bulge43is created in fin surface42such that it does not protrude beyond line45in order to enter the spatial region of fin arch41, which is defined by width44. This is achieved in that bulge43is not provided in the lower or upper end region of fin surface46, but begins spaced apart from the fin arch from the transitional region or end region of the fin surface. Region46thus serves as a gap to achieve that bulge43does not enter the region designated by44.

FIG. 6shows a corrugated fin50with fin surfaces51, which run substantially along an air flow direction according to arrow P, whereby fin surfaces51are arranged in a V-shaped or trapezoidal fashion angled to one another. Fin surfaces51are connected together by fin arches52in such a way that two fin surfaces51are always connected together at an end via a fin arch52, whereby fin surfaces51are typically connected at both ends via a fin arch52to another fin surface51. Projections53,54, which are curved outward or inward substantially in the manner of a circle or spherical shell, are provided in fin surfaces51. In this regard, projections53and54are curved in an opposite direction, so that the elements are curved alternating relative to one another. It can be seen that projection53and projection55of two opposite fin surfaces are arranged such that the projection is oriented in the opposite direction, so that they point away from one another. Adjacent projections54and56, whereby projection56cannot be seen inFIG. 6, are curved inwardly toward one another, however, so that they enter the spatial region that exists between the two adjacent fin surfaces51.

As can be seen inFIG. 6, projections53,54and55,56alternate in the lengthwise direction of the fin surfaces, whereby the structure of the embossing is the same in every second fin surface.

FIG. 7shows a further exemplary embodiment of a fin of the invention, in which the projections of fin60along a fin surface61are always formed alternatingly, so that projections62are embossed toward one side and projections63lying therebetween are embossed in the opposite direction.

In the adjacent fin surface64, curvature65is embossed in the same direction as curvature62, so that the curvatures with the same distance from the front edge always point in the same direction when viewed in the air flow direction. Alternating orientations of the curvatures at the same height always point in the same direction and no curvatures of adjacent fin surfaces are present that point toward or away from one another, but always point in the same direction.

FIG. 8shows projections which are formed elongated or oval. To this end, a series of projections73, which in the top region74are curved outward and in the bottom region75are curved inward, is introduced in fin70in fin surface71or72. This means that the projections are formed S-shaped, whereby the S in the area of its center line cuts the plane of the fin surface and in the top region faces outward and in the bottom region faces inward, so that two projections are produced, which are connected by a straight boundary surface. In contrast, the projections ofFIG. 6 or 7are arranged and formed separately from one another, whereby a planar region of the fin surface surrounds such a curved region and two projections are separated from one another. In the exemplary embodiment ofFIG. 8, the indicated S-shaped embossings are also separated from one another by a planar region of the fin surface, whereby the S-shaped embossings can also be defined as two embossings with a straight line-like connection.FIG. 8ashows a section through a projection74,75, which is formed S-shaped relative to fin surface71.

It can be seen inFIG. 8that the projections of adjacent fin surfaces are formed with an opposite curvature; this means that projections74, which point away from the adjacent fin surface, find their counterpart in the adjacent fin surface and these projections there also point away from the first fin surface. Projections75, those of the first fin surface pointing toward the adjacent fin surface, find their counterpart in the adjacent fin surface such that the related embossing also points to the first fin surface.

Adjacent projections along the extension of fin surface71are oriented parallel to one another and formed with the same orientation of the projections. This means that all projections in the top region are curved outward and the [curvatures] in the bottom region inward.

FIG. 9shows a further exemplary embodiment in which projections81of fin surfaces82of fin80in adjacent fin surfaces82,83are embossed in a different direction in such a way that projections embossed in first fin surface82in the top region point outward and the embossing in adjacent fin surface81in the top region point inward, therefore toward adjacent fin surface81, whereas in first fin surface81the projections are arranged in the top region, which point away from second fin surface81. Accordingly, the opposite applies to the bottom regions, so that in the bottom region the projections of first fin surface81point toward second fin surface81, whereby the projections of second fin surface81point away from the first fin surface. Along a fin surface81, the adjacent projections are again formed identically in the same direction, whereby the projections are formed oval and elongated and oriented substantially perpendicular to the air flow.

FIGS. 10 to 13show exemplary embodiments of corrugated fins with oval embossings, whereby inFIGS. 10 and 11the embossings are arranged at an angle, when viewed relative to the air flow direction L, whereby the angle of the orientation of the embossings is the same in each case.

A corrugated fin90with fin surfaces91,92can be seen inFIG. 10, whereby embossings93,94are provided. Embossings93of side surface92is curved counter to the direction to side surface91and projection94is curved in the direction to side surface91. Projection95of side surface91, in contrast, is curved in the direction to side surface92, and the adjacent projection96(which cannot be seen) is curved in the direction so that it points away from fin surface92. This means that the projections that are arranged as the next ones from the front edge all point toward the left, the second projections, when viewed in the air flow direction, all point toward the right, and the third projections then again point to the left, etc.

InFIG. 11projections101are arranged in fin100, which are embossed alternating in relation to projections102, and are embossed at an angle of approximately 45° to the air flow direction L. The projections of adjacent fin surfaces are embossed oppositely, which means that adjacent embossings on adjacent fin surfaces are embossed either toward or away from one another. Projection103is therefore embossed oppositely to projection101. The embossing104(not shown) which is adjacent to [projection]103is oriented toward embossing102, so that both embossings102and104are embossed toward one another.

FIGS. 12 and 13, in contrast toFIGS. 10 and 11, show projections in corrugated fins which are oriented relative to one another at a different angle to the air flow direction. In this case, the first projections are embossed which are arranged at an angle of approximately 45° to the air flow direction, whereby adjacent projections are embossed at an angle of approximately 135° to the air flow direction. The direction of the embossing corresponds to the directions inFIGS. 10 and 11, which means that inFIG. 12fins110in side surface111have a projection112that is oriented away from fin surface113, whereby adjacent projection114is embossed toward fin surface113. Projection115of fin surface113is embossed toward fin surface111, whereby the adjacent projection116(not shown) of fin surface113is oriented away from fin surface111.

Instead of an angle of 45° or 135°, other complementary angles can also be provided., It is expedient in this case, if the sum of the angles corresponds to 180°, when the angles of two adjacent projections are added.

FIG. 13shows a corrugated fin120, in which adjacent projections121,122are arranged alternating in their curvature direction, whereby adjacent projections of adjacent fin surfaces are also embossed in the opposite direction. This means that projection123of fin surface124is curved away from fin surface125, whereas projection121is also curved away from fin surface124. Adjacent projections122and125, which are arranged on fin surface124next to projection123, in contrast, are curved toward one another. In the illustrations ofFIGS. 10 to 13, adjacent projections are embossed alternating in a fin surface, whereby inFIGS. 12 and 13the angles of the orientation of the longitudinal axis of the projections are shown at a different angle.

FIG. 14shows schematically a view of a corrugated fin200with two adjacent fin surfaces201,202. In this case, projections203,204can be seen on both adjacent fin surfaces201,202, which are embossed at an angle205to one another. Advantageously, projections203,204are embossed so that the projections of adjacent fin surfaces are arranged and oriented crosswise. Here, angle205can be approximately 90°. However, other angles different therefrom can also be provided such as, for example, 120°.

FIGS. 15 to 18show a further exemplary embodiment of a corrugated fin300of the invention, in which on opposite fin surfaces301a corrugated embossing302is provided running along the fin surface. Corrugated embossing302modulates the fin surface perpendicular to the air throughflow direction. Above and below the corrugated embossing302arcuate embossings303,304are provided, which surround the corrugated embossing above and below and form a band that runs parallel to the corrugated embossing.

Corrugated embossing302thereby forms bulges305,306that extend transverse to the air throughflow direction in alternating directions.

The bulges in the same embossing direction are arranged every 7 mm to 20 mm, preferably 10 mm, so that a related periodicity is produced. As a result, the medium, such as air, is conducted in wavy lines through the fin. Thus, the bulges point alternatingly in opposite directions.

Arcuate embossings303,304above and below corrugated embossings302are also executed with this periodicity.

The bulge depth of corrugated embossings302and arcuate embossings303,304is variable and not constant over the height of the fins, as can be seen inFIG. 17.

Bulge303,304out of the trapezoidal surface of the fins is smaller in the region of trapezoid base304than in the region of trapezoid top303, but at most so large that the free passage h is 0.5 mm to 1.5 mm, preferably 0.8 mm.

The embossing having a different depth is used for minimizing a bypass in the frustum region.

A bulging into the trapezoidal surface is greater in the region of trapezoid base303′ than in the region of trapezoid top304′, but at most so large that the free passage h is 0.5 mm to 1.5 mm, preferably 0.8 mm.

The different depth of the embossing is used for minimizing a bypass in the frustum region.

The bulge height i is preferably between 60% and 95% of the fin height H, preferably 80%.

FIGS. 19 and 20show a further exemplary embodiment of a corrugated fin400of the invention, in which on opposite fin surfaces401a corrugated embossing402is provided, which runs along the fin surface. Corrugated embossing402modulates the fin surface perpendicular to the air throughflow direction. Above and below the corrugated embossing402arcuate embossings403,404are provided, which surround the corrugated embossing above and below and form a band that runs parallel to the corrugated embossing. Corrugated embossing302thereby forms bulges405,406, which extend transverse to the air throughflow direction in alternating directions.

The medium is conveyed in a wavy manner in the flow direction by corrugated embossing402with bulges403,404, whereby in each trough and peak of bulges405,406a counter-bulge407is formed, which increases the turbulence in the channel and thereby the heat transfer.

Counter-bulge407is embossed into the depth between 10% and 60% of the original bulge405,406, preferably approximately 40%.

FIGS. 21 to 24show a further exemplary embodiment of a corrugated fin500of the invention, in which on opposite fin surfaces501oval embossings502are provided, which are arranged spaced apart along the fin surface. Oval embossings502modulate the fin surface perpendicular to the air throughflow direction. Embossing502thereby forms bulges which extend transverse to the air throughflow direction in alternating directions.

The oval embossings thus form bulges, which project alternatingly into the trapezoid base-shaped cross section of fin500and out of the trapezoid base-shaped cross section of fin500.

The oval embossings form elongated oval bulges, whose longitudinal direction is inclined at an angle of 0°<α<90°, preferably 35°<α<70°, to the flow direction. The oval embossings have a narrow end region, which has a more circular shape and a further narrow end region, which is rather acute.

The bulge depth and width along the bulge shape of the embossing are not constant relative to surface501; seeFIG. 23. The bulge out of the trapezoidal shape is smaller in the region of trapezoid base503than in the region of trapezoid top504, but at most so large that the free passage h is 0.5 mm to 1.5 mm, preferably 0.8 mm. The embossing having a different depth is used for minimizing a bypass in the frustum region.

The bulge into the trapezoidal shape is smaller in the region of trapezoid top505than in the region of trapezoid base506, but at most so large that the free passage h is 0.5 mm to 1.5 mm, preferably 0.8 mm. The embossing having a different depth is used for minimizing a bypass in the frustum region.

Bulge height k corresponds to between 60% and 95% of fin height I, preferably 80%.