EP2242979B1 - Extruded tube for a heat exchanger - Google Patents

Description

The invention relates to an extruded tube for a heat exchanger according to the preamble of claim 1 and a heat exchanger with an extruded tube according to the invention and to a method for producing an extruded tube according to the invention.

US 3,596,495 A describes by extrusion and drawing manufacturable tubes for a heat exchanger, in which according to an embodiment, a plurality of chambers are separated by inner webs. In addition, the chambers are deformed by externally introduced dents both in the region of the side walls and in the region of the webs to produce turbulence of a fluid flowing through.

It is the object of the invention to provide an extruded tube for a heat exchanger, in which a particularly high heat transfer is achieved at a relatively low pressure drop across the extruded tubes.

This object is achieved according to the invention for an initially mentioned extrusion tube with the characterizing features of claim 1. Due to the controlled orientation of the bulges of the web, a targeted accurate shaping of the channel can be achieved not only in the vertical direction, but also in the transverse direction. In contrast, according to the aforementioned prior art in the transverse direction, only an uncontrolled narrowing of the channels was possible by randomly bulging the web with respect to the orientation.

In a preferred embodiment, it is provided that at least one of the channels of the extrusion tube in the longitudinal direction has a regular, wavy course with respect to the transverse direction. As a result, on the one hand, the turbulence and the heat transfer are increased and on the other constrictions are avoided, which can cause excessive pressure drop and possibly blocking by addition of fluid or substances precipitated from the fluid. Particularly preferred is a distance in the transverse direction between two adjacent webs substantially constant.

In the interest of a simple and reliable production at least one of the impressions an elongated shape, wherein a plurality of webs covered by the same indentation and bulged. The elongated imprint has an orientation angle to the transverse direction so that bulges of sidewalls and webs resulting from the same imprint are not at the same height in the longitudinal direction of the tube. Such an orientation angle is approximately between 0 ° and 45 °, preferably approximately between 20 ° and 45 °, and particularly preferably approximately between 28 ° and 42 °.

Alternatively or additionally, it can be provided that at least one of the indentations is essentially only in overlap with the at least one web. Another imprint can not be in overlap with a bridge. In this way, indentations for bulging the side walls and embossments for buckling the webs are spatially separated from each other separately placed, so that there is a particularly large design opportunity for the formation of the channels. Such an isolated embossment of a side wall may in particular have an orientation with respect to the transverse direction. An orientation angle of this impression relative to the transverse direction may advantageously be approximately between 0 ° and 45 °, preferably approximately between 25 ° and 45 °, and particularly preferably approximately between 30 ° and 40 °.

For particularly effective generation of turbulence, at least one of the indentations may be winglet-shaped. In an optimized form, the winglet-shaped embossment has a ratio of length to width of between 2 and 5, preferably between 2.3 and 4 and particularly preferably between 2.5 and 3.2. According to an advantageous variant, the winglet-shaped embossing has a ratio of length to width of between 1.2 and 5, preferably between 1.5 and 3 and particularly preferably between 1.8 and 2.5.

It has been shown that too long indentations can also lead to a planar deformation of the side walls or can cause the short side walls to buckle. As a result, the external dimension of the extruded tube is disadvantageously changed and the coolant flow is impaired, and the deformation of the extruded tube in the region of the indentation can cause the side wall to buckle and the block cross section to become blocked or reduced, and thus to increased pressure loss.

In general terms, it is provided that the orientations of at least some bulges of adjacent webs, which lie substantially at the same height in the longitudinal direction, are the same. This allows a substantially constant cross-section of the channel at least with respect to the transverse direction, so that the risk of blockages due to deposits, for example, when used for exhaust gas cooling, is low. Alternatively, it may also be provided according to requirements, however, that the orientations of at least some bulges of adjacent webs, which lie in the longitudinal direction substantially at the same height, are opposite. As a result, it is possible to design bottlenecks of the pipes in a controlled manner, by means of which particularly great turbulence can be generated. This can be advantageous if the risk of blockages due to deposits is low, for example in the case of intercoolers, coolant coolers, exhaust gas coolers for low-pressure EGR or high-pressure EGR coolers with moderate soot and / or HC emissions.

In an advantageous detailed design, a buckling of one of the side walls and a bulging of the web are provided alternately one behind the other in the longitudinal direction of a channel in order to produce a uniform turbulence in all spatial directions. In the longitudinal direction of a channel, a bulging of the web in a first orientation in the transverse direction, followed by a bulging of a first of the two side walls, following a bulging of the web in the respective other orientation and subsequent bulging of the respective other side wall is particularly advantageous. As a result, a screwed course of the channel is generated, which advantageously acts on the fluid flow with a swirl. Over the length of the extruded tube, a plurality of such sections may be provided with in particular different swirl direction.

A further advantageous embodiment provides to make the bulging of the webs and / or the channel walls alternately in opposite directions, so that there is an alternating acceleration and deceleration of the flow.

In a further embodiment, in the longitudinal direction of a channel, bulges of two webs delimiting the channel at the same height lie opposite each other and are directed toward one another, so that the channel width is reduced by the bulges. As a result, an acceleration of the flow can be achieved at this bottleneck. Alternatively or additionally, it is provided that bulges in the longitudinal direction of a channel two of the channel limiting webs lying at the same height, facing away from each other have bulges, so that the channel width is increased by the bulges. As a result, a slowdown of the flow can be achieved at this point. As previously noted, in a preferred embodiment, alternate broadening and narrowing of the channels may also be provided.

In an advantageous detailed design, it is provided that the bulge of the web is formed both by an impression of the first side and an at least partially overlapping impression of the second side. As a result, a particularly clear bulging of the web can be achieved with only a slight bulging of the side walls. In a first variant, the orientation of the bulge with respect to the embossed imprints is opposite. In an alternative or supplementary second variant, the orientation of the bulge is rectified with respect to the embossed impressions.

In a simple realization of an extrusion tube according to the invention, the controlled-oriented bulging of the web takes place by means of a stamping tool inclined relative to the side walls. As a result, during embossing, a transversely oriented force is exerted on the web, so that the direction of its bulging or buckling is predetermined. In an alternative or supplementary solution, the controlled-oriented bulging of the web takes place by means of an embossing tool acting off-center relative to the web. In particular, the embossing tool can be only about as wide as the web in the transverse direction and the deviation of the embossing center of the web center be relatively low, so that a controlled directed buckling of the web and on the other hand, the side wall adjacent to the web as little as possible in the High direction is dented.

In order to be able to define the extrusion tubes according to the invention simply and sealingly in a bottom of a heat exchanger, an end-side region of the extrusion tube is preferably not provided with bulges. One Distance of a pipe end to a first embossing is advantageously about between 2 mm and 15 mm, more preferably between about 4 mm and 8 mm. In an alternative embodiment example, a distance of a pipe end up to a first embossing is advantageously between approximately 4 mm and 20 mm, particularly preferably approximately between 6 mm and 12 mm.

In an advantageous embodiment of the invention, an extruded tube has a bent region, so that the heat exchanger may be, for example, a U-flow heat exchanger or is generally adapted by the bending of the tubes to a predetermined space. To avoid an excessive narrowing of the channel in which in the bent region there is expediently an at least reduced depth of the bulges present. Particularly preferably, no bulges are arranged at least in sections in the bent region.

In a preferred detailed design, the tube material consists of one of the group aluminum alloy, AlMn alloy, AlMg alloy and AlMgSi alloy. Such light metal alloys are particularly easy to extrude and deformable with the indentations according to the invention. It has been found that extruded tubes made of such alloys, even when used as an exhaust gas cooler, have good corrosion resistance to aggressive condensate.

With optimized geometry of the extrusion tubes, a depth of the impressions is less than about 75%, preferably less than about 45%, and more preferably less than about 30% of an inner tube diameter in the vertical direction.

Furthermore, it has been shown in experiments that in the longitudinal direction a distance between an embossing of the underside of the tube to a subsequent embossing of the tube top side is advantageously not more than 10 times, preferably not more than 6 times and particularly preferably not more than 3, 5 times an inner pipe diameter in the vertical direction is. In addition, an optimized execution has the property that in the In the longitudinal direction, a distance between an embossment for bulging a side wall to a subsequent embossment for bulging a web is not more than 8 times, preferably not more than 6 times and particularly preferably not more than 3 times an inner pipe diameter in the vertical direction is.

In the case of embossments extending across a plurality of webs in the transverse direction, a length of the embossing in the transverse direction is optimally approximately between 25% and 100%, preferably between 35% and 90% and particularly preferably between 45% and 80% of a width of the extruded tube in the transverse direction.

In the case of an indentation limited only between two webs, their length in the transverse direction is approximately between 25% and 130%, preferably between 35% and 95% and particularly preferably between 45% and 75% of a width of the channel bounded by the webs transverse direction.

Generally advantageous for improving the heat transfer on at least one of the side walls from the outside a rib member is arranged, in particular by means of material connection. This may in particular be a surface soldering. To ensure the most uniform possible heat transfer between ribs and extrusion tubes, it is advantageous that a repeat unit of the indentations in the longitudinal direction and a repeat unit of ribs of the rib member are not integer multiples of each other. As a result, unfavorable regular overlaps of contact surfaces of the ribs can be avoided with embossed areas of the tube surface.

In order to further improve heat transfer, in an extrusion tube according to the invention, at least one half-leg may project from one of the side walls into one of the channels.

In an optimized embodiment, one is four times the ratio of the area of the flow-through cross-section to a through the first fluid wettable perimeter of defined hydraulic diameters in a range between 1.2 mm and 6 mm.

In particular, preferred ranges of the hydraulic diameter are between about 2 mm and about 5 mm, particularly preferably between 3.0 mm and 3.4 mm, particularly preferably between 3.1 mm and 3.3 mm and in particular about 3.2 mm.

In general, and in particular for designs of high-pressure heat exchangers, it has been found that the hydraulic diameter (ie) is advantageously between about 2.5 mm and 4 mm, particularly preferably between about 2.8 mm and 3.8 mm.

In general, and in particular for designs of low-pressure heat exchangers, it has been found that the hydraulic diameter (ie) is advantageously in a range between 2 mm and 3.5 mm, particularly preferably between 2.5 mm and 3.5 mm.

In order to optimize the weight and the amount of material, a ratio of the hydraulic diameter (dh) and a channel shell thickness (s) is advantageously in a range between 0.8 and 8, preferably in a range between 1.2 and 6 and particularly preferably in a range between 1,4 and 6. For the same interest, a ratio of a web thickness (d) and a channel shell thickness (s) is preferably below 1.0.

Generally, a ratio of a circumference of the extruded tube and the circumference wetted by the first fluid lies in a range between 0.1 and 0.9, in particular between 0.1 and 0.5, the latter range being particularly suitable for exhaust gas coolers.

In an optimized design of an embodiment, a ratio of a distance (e) between two in particular opposite and / or staggered partial webs to a height (b) of the pipe cross-section is in a range below 0.8, more preferably in a range between 0.3 and 0.7 is. A ratio of a distance (a3) a first partial web to a full web to a distance (a4) of a second partial web to the whole web is preferably in a range between 0.5 and 1.0, particularly preferably in a range between 0.6 and 0.8 in a corresponding design.

In general, to increase the service life and in particular when involving a fluid having corrosive properties, such as exhaust gas, it may be provided that at least one web and / or the channel jacket, preferably the channel jacket inner side, has a corrosion protection, preferably in the form of a galvanizing and / or a paint.

Depending on the requirements, a cross section of the extruded tube may advantageously be rectangular, oval or semi-oval, for example.

In a particularly suitable design of an extruded tube for use in a heat exchanger, a number of 2 to 20, preferably 5 to 15, more preferably 7 to 12, particularly preferably 8 to 11 and particularly preferably 9 webs are arranged side by side over a tube cross-section.

The object of the invention is also achieved according to claim 11 by a heat exchanger with an extruded tube according to the invention. In the extrusion tube, a first fluid is passed, which exchanges heat with a second fluid flowing around the tube outside. Such heat exchangers find widespread use, especially in motor vehicles, whereby optimization of the heat exchange performance due to the indentations according to the invention is particularly advantageous due to the high demands on weight and installation space.

In a preferred embodiment, the extruded tubes are circulated air. In an alternative embodiment, the extrusion tubes can also be flowed around by a cooling liquid, for example in the case of an indirect exhaust gas cooler of a motor vehicle.

The heat exchanger according to the invention may be an exhaust gas cooler for cooling a recirculated exhaust gas flow, but also a charge air cooler of an internal combustion engine, an oil cooler or a coolant radiator. Particularly preferably, these heat exchangers are each used in a motor vehicle.

The object of the invention is achieved by a manufacturing method for the extrusion tube by the features of claim 17. Advantageously, the extruded profiles are first formed in the manner of a continuous prismatic body by a known extrusion process and subsequently introduced the imprints. This can take place in a step immediately following the extrusion, in particular also when the profile is still warm, or else in a completely separated step on a cooled and / or interposed profile strand.

In an advantageous detailed design, the embossing is effected by means of an embossing roller. Alternatively or additionally, however, it can also be done by means of an embossing stamp.

In a preferred embodiment, a stamping subsequent step of separating the extruded tubes is provided by an endless or quasi-endless profile strand to optimize the manufacturing cost. This can be done for example by a sawing process. In a particularly advantageous detailed design, however, the separation takes place by a tearing off, in particular after a previous scoring. As a result, the occurrence of chips in the course of the separation can be largely avoided.

Further advantages and features of the invention will become apparent from the embodiments described below and from the dependent claims.

According to a preferred embodiment, the orientations of at least some bulges of adjacent webs, which lie in the longitudinal direction substantially at the same height, opposite, being preferred in the longitudinal direction of a channel a bulge of one of the side walls and a bulge of the web are provided alternately one behind the other, wherein preferably in the longitudinal direction of a channel initially a bulge of the web in a first orientation in the transverse direction, followed by a bulge of a first of the two side walls, below a bulging of the web in the respective other orientation and subsequent bulging of the respective other side wall, wherein preferably in the longitudinal direction of a channel bulges of the channel delimiting two webs lying at the same height, oppositely directed bulges have, so that the channel width is reduced by the bulges , wherein preferably in the longitudinal direction of a channel bulges of the channel delimiting two webs lying at the same height, directed away from each other buckling, so that the channel width is increased by the bulges, wherein preferably the Ausb eulung of the web is formed both by an impression of the first side and an at least partially overlapping imprint of the second side, wherein particularly preferably the orientation of the bulge with respect to the overlapping indentations is opposite or rectified.

According to a preferred embodiment, the controlled-oriented bulging of the web is effected by means of an embossing tool inclined relative to the side walls, wherein preferably the controlled-oriented bulging of the web takes place by means of an embossing tool engaging eccentrically relative to the web, preferably an end-side region of the extruded tube not provided with bulges is, wherein preferably a distance of a pipe end to a first embossing is approximately between 2 mm and 15 mm, in particular approximately between 4 mm and 8 mm.

According to a preferred embodiment, the extruded tube has a bent region, wherein preferably in the bent region an at least reduced depth of the bulges, preferably in the bent portion at least partially no bulges are arranged, wherein preferably the tube material from one of the group aluminum alloy, AlMn Alloy, AlMg alloy and AlMgSi alloy Preferably, wherein a depth of the impressions is less than about 75%, in particular less than about 45%, in particular less than about 30% of an inner tube diameter in the vertical direction, preferably in the longitudinal direction, a distance between an impression of a side wall to a subsequent impression of the other side wall is not more than 10 times, in particular not more than 6 times, in particular not more than 3.5 times an inner tube diameter in the vertical direction, wherein preferably in the longitudinal direction, a distance between an impression for buckling a side wall to a subsequent embossment for buckling a web is not more than 8 times, in particular not more than 6 times, in particular not more than 3 times an inner pipe diameter in the vertical direction, preferably a length of a several cross-web embossing in the transverse direction approximately between 25% and 100%, in particular between 35% and 90%, in particular between 45% and 80%, of a width of the extruded tube in the transverse direction, wherein preferably a length of an embossment arranged between two webs in the transverse direction is between approximately 25% and 130%, in particular between 35% and 95%, in particular between 45% and 75% of a width of the channel bounded by the webs in the transverse direction.

According to a preferred embodiment, a rib element is arranged on at least one of the side walls from the outside, in particular by means of a material-locking connection, preferably a repeat unit of the indentations in the longitudinal direction and a repeat unit of ribs of the rib element are not integer multiples of each other, wherein preferably at least one half-leg of a the side walls protrudes into one of the channels.

According to a preferred embodiment, a hydraulic diameter defined as four times the ratio of the area of the flow-through cross-section to a periphery wettable by the first fluid is in a range between 1.2 mm and 6 mm, wherein the hydraulic diameter is preferably between approximately 2 mm and about 5 mm, in particular between 3.0 mm and 3.4 mm, in particular between 3.1 mm and 3.3 mm, in particular about 3.2 mm, wherein preferably the hydraulic diameter between about 2.5 mm and 4 mm, in particular between about 2.8 mm and 3.8 mm, in particular for a high pressure heat exchanger, preferably the hydraulic diameter is in a range between 2 mm and 3.5 mm, in particular between 2.5 mm and 3.5 mm, in particular for a low-pressure heat exchanger, preferably a ratio of the hydraulic diameter and a channel sheath thickness in a range between 0.8 and 9, in particular in a range between 1.2 and 6, in particular in a range between 1.4 and 6, wherein preferably a ratio of a web thickness and a channel coat thickness is less than 1.0, wherein preferably a ratio of an outer circumference of the extrusion tube and the wettable by the first fluid circumference in a range between 0.1 and 0.9, in particular between 0.1 and 0.5, wherein preferably a ratio of a distance s between two, in particular opposite and / or mutually offset partial webs to a height of the tube cross section in a range below 0.8, in particular in a range between 0.3 and 0.7, wherein preferably a ratio of a distance of a first Partial web to a full web to a distance of a second part of the web to the whole web, in a range between 0.5 and 1.0, in particular in a range between 0.6 and 0.8.

According to a preferred embodiment, at least one web and / or the channel jacket, preferably the channel jacket inner side, a corrosion protection, preferably in the form of a galvanization and / or a lacquer, wherein preferably a cross section of the extruded tube is rectangular, oval or semi-oval, preferably a Number of 2 to 20, in particular 5 to 15, in particular 7 to 12, in particular 8 to 11, in particular 9 webs are arranged side by side over a pipe cross-section.

According to a preferred embodiment, the extruded tubes of the heat exchanger are circulated air, wherein preferably the extruded tubes are flowed around by a cooling liquid, wherein preferably the heat exchanger Exhaust gas cooler for cooling a recirculated exhaust gas flow, a charge air cooler, an oil cooler or a coolant radiator is.

According to a preferred embodiment of the method, the embossing is effected by means of an embossing roll, wherein preferably the embossing is effected by means of a stamping die, wherein preferably the embossing is followed by a step of separating the extruded tubes from an endless or quasi-endless profile strand, wherein preferably the separation by a sawing process or by a tear-off, in particular after a previous scoring takes place.

Fig. 1

zeigt eine schematische Darstellung eines Strangpressrohrs zur Definition der einzelnen Raumachsen.

Fig. 2

zeigt ein erstes Ausführungsbeispiel eines erfindungsgemäßen Strangpressrohrs mit insgesamt neun Abwandlungen 2.1 bis 2.9.

Fig. 3

zeigt eine Darstellung von Prägevorgängen zur Herstellung eines Strangpressrohrs nach Fig. 2.

Fig. 4

zeigt eine räumlich Darstellung eines Strangpressrohrs nach dem ersten Ausführungsbeispiel.

Fig. 5

zeigt einen Ausschnitt aus dem Strangpressrohr nach Fig. 4.

Fig. 6

zeigt ein Strangpressrohr mit zehn Abwandlungen 6.1 bis 6.10.

Fig. 6a

zeigt weitere Abwandlungen 6.11 bis 6.15 des Strangpressrohrs.

Fig. 7

zeigt räumliche Ansichten zweier Prägewalzen zur Herstellung eines Strangpressrohrs.

Fig. 8

zeigt eine auf Messungen und Rechnungen beruhende Darstellung einer bevorzugten Wahl eines hydraulischen Durchmessers in Bezug auf das Verhältnis aus dem durch das erste Fluid benetzbaren Umfang und einem äußeren Umfang des Strangpressrohrs.

Fig. 9A und 9B

zeigen zwei Abwandlungen einer bevorzugten Ausführungsform eines Querschnitts eines Strangpressrohrs mit stranggepresstem Kanalmantel und mit dem Kanalmantel stranggepressten Stegen.

Fig. 10A und Fig. 10B

zeigen zwei Abwandlungen einer weiteren Ausführungsform wie in Fig. 9A und Fig. 9B mit Teilstegen.

Fig. 11A und Fig. 11B

zeigen zwei Abwandlungen einer weiteren Ausführungsform wie in Fig. 9A und Fig. 9B mit Teilstegen.

Fig. 12

zeigt eine weitere Ausführungsform eines Querschnitts eines Strangpressrohrs mit Teilstegen.

Fig. 13

zeigt eine weitere Ausführungsform eines Querschnitts eines Strangpressrohrs mit Teilstegen.

Hereinafter, several preferred embodiments of the invention will be described and explained in more detail with reference to the accompanying drawings.

Fig. 1

shows a schematic representation of an extrusion tube for defining the individual spatial axes.

Fig. 2

shows a first embodiment of an extrusion tube according to the invention with a total of nine modifications 2.1 to 2.9.

Fig. 3

shows a representation of embossing processes for producing an extruded tube after Fig. 2 ,

Fig. 4

shows a spatial representation of an extrusion tube according to the first embodiment.

Fig. 5

shows a section of the extrusion tube after Fig. 4 ,

Fig. 6

shows an extrusion tube with ten modifications 6.1 to 6.10.

Fig. 6a

shows further modifications 6.11 to 6.15 of the extruded tube.

Fig. 7

shows spatial views of two embossing rolls for producing an extruded tube.

Fig. 8

shows a measurement and calculations based on a preferred choice of a hydraulic diameter with respect to the ratio of the wettable by the first fluid circumference and an outer circumference of the extruded tube.

Figs. 9A and 9B

show two modifications of a preferred embodiment of a cross section of an extruded tube with extruded channel jacket and extruded with the channel jacket extruded webs.

10A and 10B

show two modifications of another embodiment as in Figs. 9A and 9B with partial webs.

FIGS. 11A and 11B

show two modifications of another embodiment as in Figs. 9A and 9B with partial webs.

Fig. 12

shows a further embodiment of a cross section of an extrusion tube with partial webs.

Fig. 13

shows a further embodiment of a cross section of an extrusion tube with partial webs.

As shown Fig. 1 The invention relates to extruded tubes which extend at least in sections in a longitudinal direction designated z. The extruded tubes have an elongated extension transversely to the longitudinal direction, wherein they are in particular formed as flat tubes. A transverse direction in the sense of claim 1 is in Fig. 1 referred to as y-direction, wherein the (long) side walls 1, 2 of the extruded tube extend substantially in this direction. A high direction is in Fig. 1 denoted by x and extends perpendicular to the longitudinal direction and the transverse direction. The side walls 1, 2 do not necessarily have to extend straight in cross-section but can also run in a curved manner and in this sense are oriented only "substantially" in the transverse direction or "at least approximately parallel".

The side walls 1, 2 are connected to each other via shorter, curved, substantially in the vertical direction extending narrow sides 3, 4 to form a closed flat tube.

Within the flat tube, the side walls are connected via a plurality of continuous webs 5, 79, 89 with separation of separate channels 6. In addition to these continuous webs or full webs 5, 79, 89 may optionally (see, for example Fig. 4 or FIGS. 10A to 11B ) also partial webs 5 ', 79', 89 'are provided, which protrude in the manner of fins to increase the contact area between the channel wall and fluid in the channels 6.

To optimize the turbulence of the fluid flowing through the extrusion tubes are provided with indentations 7, are formed by the longitudinal direction with respect to local bulges, which protrude into the channels 6 and influence the fluid flow. These may be bulges of the side walls 1, 2, which protrude correspondingly in the vertical direction or even buckling or buckling of the continuous webs 5, 79, 89, which protrude accordingly in the transverse direction. Such bulges of the webs are achieved in that an impression is made at least partially covering the neck region of the web on the side wall.

• Zum einen kann ein Prägestempel 8 (siehe Fig. 3) oder auch eine Prägewalze 9' (siehe Fig. 7) eine geneigte Prägekante 8a, 10' aufweisen. In Fig. 3 ist unter A eine einfache Prägung eines Strangpressrohrs mittels einer einen Großteil des Strangpressrohrs in Querrichtung überdeckenden, glatten und
• nicht geneigten Prägekante gezeigt, mittels der die Stege 5 unkontrolliert nach links oder nach rechts ausgebeult werden. Unter B ist die Prägekante dagegen mit einem Winkel Alpha von wenigen Grad, typisch nicht mehr als zehn Grad, relativ zu der Seitenfläche 1 versehen. Hierdurch werden sämtliche der Stege 5 im Beispiel B kontrolliert nach rechts ausgebeult, da die Kräfte beim Prägen im Bereich der Ansätze der Stege asymmetrisch angreifen.

By suitable measures it is achieved that the orientation of the bulge of the web in the transverse direction is predetermined in a controlled manner and is not arbitrary or random. In order to achieve this, two different paths can be taken during the production of the embossments:

• On the one hand, an embossing stamp 8 (see Fig. 3 ) or an embossing roller 9 '(see Fig. 7 ) have an inclined embossing edge 8a, 10 '. In Fig. 3 under A is a simple embossing of an extruded tube by means of a much of the extrusion tube in the transverse direction overlapping, smooth and
• not inclined embossing edge shown by means of the webs 5 uncontrollably bulging to the left or to the right. By contrast, under B, the embossing edge is provided with an angle alpha of a few degrees, typically not more than ten degrees, relative to the side surface 1. As a result, all of the webs 5 in example B are controlled to the right, since the forces during embossing in the area of the extensions of the webs attack asymmetrically.

On the other hand, a check of the buckling direction can also be achieved for punctiform impressions. For this purpose in the example C is the Fig. 3 a serrated embossing edge 8b shown only with small local projections or punctiform attacks on the extrusion tube. The points of attack are essentially located over the webs 5, but slightly eccentric to it. This also buckling of the webs 5 is achieved in a predetermined orientation with respect to the transverse direction. The direction of the bulging of the webs 5 would also be in the example C to the right, since the embossing points each attack slightly to the left of the center of the webs 5.

An alternative to embossing stamps 8 alternative or complementary possibility of a substantially point-like embossment with local projections over the in Fig. 7 shown embossing roll 9 with point-like local projections 10 given. The likewise in Fig. 7 In contrast, embossing roller 9 'shown has elongate projections 10', which extend over at least an entire channel width or over the substantially entire width of the extruded profile. With such a roller 9 ', for example, embodiments such as those in Fig. 4 be prepared, with the local projections of the embossing roll 9 versions as in Fig. 6 and Fig. 6a can be produced. In principle, however, the two types of projections 10, 10 'can also be provided together on the same embossing roller.

In the present case, a first embodiment is essentially according to Fig. 2 and a second extrusion tube Fig. 6 each shown with several modifications. According to the first embodiment Fig. 2 it is impressions of the first type with smooth, inclined embossing edges, each overlap more than one web 5 of the extruded tube at the same time and thus at the same time bulge the side walls between the webs inwards. Suitably, the embossing edges or indentations are arranged at an orientation angle relative to the transverse direction. As a result, by the same indentation conditional bulges of adjacent webs are offset in the longitudinal direction to each other, so that in a simple manner a wave-like modulation of the channels 6 is achieved in the transverse direction largely constant distance of the channel walls. Such an orientation angle is in typical embodiment about 35 ° and is given in the examples 2.3 to 2.9 respectively. Such impressions with an angle to the transverse direction course are particularly well suited, with a surface soldered on the extruded tube cooling fin (not shown) to be combined, since unfavorable coverage of embossments and ribs is avoided, resulting in areas of poor heat dissipation.

In general, in the examples 2.1 to 2.9 impressions from the upper side as solid lines and not visible in the plan view indentations from the bottom are shown as dashed lines. The controlled buckling direction of the webs is shown as a directional arrow within the indentations.

The impressions are expediently made in both side surfaces 1, 2. These opposite impressions can overlap (eg Fig. 2 Ex. 2.2, 2.4) or alternatively arranged offset in an alternating manner (eg 2.1, 2.3). The orientation angles of the impressions can vary and, in particular, alternate as in Examples 2.5, 2.8 and 2.9. It can be provided over the width of the extruded tube also several transversely shorter embossments with varying orientation angles, see for example Examples 3.6 to 3.9.

In some of the examples described, for example in case 2.1, 2.3 or also 2.7, the bulging directions of the webs are made by impressions from above opposite those in the longitudinal direction alternately from below impressions to achieve the highest possible turbulence generation at moderate pressure loss increase.

In the extrusion tube after Fig. 6 These are largely local impressions of the second type. Unlike the first case after Fig. 2 In this case, an embossing is not made over the entire width of the pipe, but limited only locally. This has the advantage that the buckling of the pipe webs and the constriction of the channel height in the vertical direction can be done separately in succession. This results in an additional design flexibility, which is very helpful especially with regard to the generation of a swirling flow in the channels. In this way even more complex 3-dimensional vortex and flow states can be generated than in the first case.

Advantageously, the indentations in the longitudinal direction are alternately mounted in the form that in the flow longitudinal direction after an expression of the pipe webs an expression of the pipe wall takes place and then again an expression of the pipe webs etc. The manifestations may additionally be applied alternately on both side walls 1, 2 and in particular in the form that in the longitudinal direction after buckling of a web 5 in one direction by an indentation 7 on the upper side wall 1 an impression of the lower side wall 2 takes place, in the longitudinal direction below the buckling of a web 5 in the other orientation direction by an impression 7 on the lower side wall 2 and longitudinally following an impression 7 of the upper side wall 1. Thereafter cyclically repeats the expression of the webs by buckling a ridge 5 in the first direction by an impression on the upper side wall 1 etc .. Any a Other combinations and sequences of impressions in the flow direction is also conceivable, see exemplary representations 6.1 to 6.17 in Fig. 6 and 6a , In the illustrations, those indentations that bulge due to spatial coverage of a web 5, each have a directional arrow. A deviation from the central position is not shown in the drawings for reasons of clarity. In principle, only a small controlled deviation of the embossing punch from the center position over a web 5 is required in order to predetermine the bulging direction of the web.

In order to achieve as strong and uniform bulging of the webs, these can be bagged on both sides of the top and bottom, as in Fig. 6a , Example 6.11 to 6.13 shown. In this case, impressions of the side walls acting on the webs are in each case at least partially overlapping, so that the web is bulged at the same location starting from both side walls. The direction of the bulge with respect to the overlapping indentations can be rectified (see about 6.11 and 6.13) or also directed in opposite directions (see 6.12).

Due to the nature of the pipe webs and the pipe walls, on the one hand there is a reduction of the hydraulic diameter and thus an increase in the performance of the pipes in terms of heat transfer, on the other hand also to a directed flow deflection both in the y-z plane and in the x-z plane

Fig. 6 shows advantageous impressions example of a pipe with three intermediate webs 5. In a solid line in each case the impression of the upper side wall 1, in dashed line the impression of the lower side wall 2 is shown. An arrow shows the direction of the ridge buckling. Depending on the requirements, the indentations in the x-, y-, and z-directions can be round, oval, oval oblong rectangular or even in another form. The impressions are made alternately as described above. The deformation of the sewer pipe wall at one point can be carried out by one or even two characteristics per channel (see, for example, Examples 6.4, 6.5, 6.9 and 6.10). However, in special cases, especially with very wide channels, this can also be done by more than two impressions in one place.

In Fig. 6.3 are impressions of the side walls 1, 2 shown between the webs 5, which are aligned at a defined orientation angle to the transverse direction. The orientation angle of the indentation with respect to one of the axes z and y in the present case is approximately between 30 ° and 40 °. There are any other combinations between deflection and Einprägranghenfolge beyond the illustrated variants also conceivable.

The examples 6.4, 6.5, 6.9 and 6.10 show variants with winglet-like, ie oblong and preferably angled embossed impressions between the webs 5. Depending on the requirements beyond the illustrated embodiments, any combination of winglets to each other both in position and orientation to each other as well Direction of the bars conceivable. For the embossments in the form of winglets, it has been found that an orientation angle of the embossment with respect to one of the axes z and y is particularly preferably between about 28 ° and 42 °. In order to increase the turbulence still further, it can also be provided, in particular for very wide channels, in addition to the illustrated variants, to impress more than just one winglet per channel in the transverse direction.

The shape of the winglets is chosen so that the ratio of their length to their width is a multiple, in particular about 1.8 times to 2.5 times or about 2.5 times to 3.2 times.

Impressions between the webs 5 in winglet shape over simpler embossed impressions have the advantage that with this type of flow control even higher heat transfer performance can be achieved because the flow undergoes an even more directed deflection with a much higher turbulence.

For both embodiments according to Fig. 2 and Fig. 6 applies that when using very heavily contaminated fluids such as exhaust gas of an internal combustion engine with the narrowing of the channels 6, the risk of blocking by addition of components from the gas phase, in particular soot and / or unburned hydrocarbons grows. Therefore, in this case, the bulges of the webs 5 are designed so that they always bulge in the transverse direction in the same orientation, so that the free channel spacing between adjacent webs 5 does not or only slightly changes. In the longitudinal direction, the webs thus have a parallel waveform with respect to each other with respect to the transverse direction.

Depending on the application, however, it may also be advantageous to exhibit the webs 5 in such a way that the orientation of the bulges of adjacent webs 5 are exactly opposite each other in order to narrow the channel 6 alternately as much as possible and then to expand again as much as possible. An example of such an arrangement is in Fig. 6a , Example 6.13. By this alternate narrowing and extension of the channel cross-section, an additional performance increase for deposition-critical applications such as charge air cooler, coolant radiator, oil cooler or exhaust gas cooler for low-pressure EGR applications or high-pressure EGR applications with moderate soot and / or HC emissions is possible. Depending on requirements always consider the appropriate compromise with a pressure drop resulting from the turbulences and constrictions.

In Fig. 6a Examples 6.14 and 6.15 illustrate another possibility of having both the side wall and the web / the limiting webs buckling with only one indentation in that the stamp, in addition to the channel width, also has a part or more of that of the adjacent one Footbridges covered. In addition to the in Fig. 6.14 and 6.15 Variants shown are all conceivable combinations of ridge buckling for Kanaleinprägungsrichtung conceivable here.

For a dimensional accuracy of the outer dimensions of the extruded tube, it is advantageous to not bulge the final narrow sides 3, 4 by indentations. In this case, however, takes place in the two laterally outer channels only a wave-shaped bulge of the arranged closer to the tube center web, while the outer wall remains undeformed. Depending on the application, it is therefore advantageous to provide the outer channels with a larger or smaller flow cross-section, in the first case, the risk of blocking the gas channel by the strong reduction of the distance between the web 5 and outer narrow side 3, 4 in the To minimize buckling, or in the second case also in the outer channel 6 to achieve a similar high turbulence as in the inner channels. If no special requirements are placed on the outer dimensions of the extruded tube, it may of course be expedient also to provide the narrow sides 3, 4 with indentations and to bulge in the transverse direction.

• Zum Fügen der Strangpressrohre in einen Rohrboden ist es vorteilhaft, die Ausprägungen in den Endbereichen nicht zu prägen, damit ein definiertes Einbringen der Strangpressrohre mit umlaufend konstanten Spalt in den Boden möglich ist und somit eine gute Fügung der Strangpressrohr-Boden-Verbindung gewährleistet ist. Ein weiterer Grund besteht darin, dass ein definiertes Aufweiten der Strangpressrohre zur Fixierung von Strangpressrohr und Boden über eine gemeinsame Anlagefläche möglich bleibt.

For joining the extruded tubes into a floor and for the design of the pipe ends:

• For joining the extruded tubes in a tube sheet, it is advantageous not to emboss the shapes in the end regions, so that a defined introduction of the extruded tubes with circumferentially constant gap in the ground is possible and thus a good joining of the extruded tube-ground connection is guaranteed. Another reason is that a defined Expansion of the extruded tubes for fixing of extruded tube and floor remains possible via a common contact surface.

The required distance of the profile end to the first embossing is particularly dependent on the depth of the impressions. The distance is to be selected so that in the area of the joint no or only a very small deformation of the original pipe geometry occurs. In typical cases of heat exchangers dimensioned for use in motor vehicles, this means a distance between 2-15mm, especially 4-8mm. In special cases, however, this measure can also go beyond these distances.

• Ein großer Vorteil der Strangpressrohr-Wärmetauscher gegenüber anderen Tauscherrohren, z.B. Edelstahl-Rohren, ist die sehr große Designflexiblilität, insbesondere durch die Möglichkeit, die Strangpressrohre zu biegen.

For bending the stamped extruded tubes:

• A major advantage of the extruded tube heat exchangers over other exchanger tubes, eg stainless steel tubes, is the very great design flexibility, in particular the possibility of bending the extruded tubes.

For bending the extruded tubes, it is particularly advantageous if indentations are dispensed with in the region of the bend in order to prevent excessive deformation and possibly even closure of individual channels. Alternatively, in the bending region, the embossing depth can only be reduced or, for example, only one embossing of the webs or only a constriction of the channel walls can be provided. In the manufacturing process, first the embossing of the tubes and then the bending into the desired shape.

• Die Herstellung der Einprägungen kann vorteilhaft auf zwei alternative oder auch kumulative Arten erfolgen:
  • 1) Das Strangpressrohr wird mittels mindestens einer Werkzeugwalze geprägt. In Fig. 7 ist eine solche Walze 9 beispielhaft abgebildet. Vorteilhaft werden mindestens zwei gegenläufige Werkzeugwalzen verwendet, durch welche in einem Arbeitsgang sowohl die obere Seitenwand 1 als auch die untere Seitenwand 2 geprägt werden.
  • 2) Das Strangpressrohr wird über einen Stempelsatz bzw. diverse Einzel-Prägestempel geprägt.

For the method of preparation:

• The impressions may advantageously be produced in two alternative or cumulative ways:
  • 1) The extrusion tube is embossed by means of at least one tool roll. In Fig. 7 Such a roller 9 is shown by way of example. Advantageously, at least two counter-rotating tool rolls are used, by which both the upper side wall 1 and the lower side wall 2 are embossed in one operation.
  • 2) The extrusion tube is stamped on a stamp set or various single dies.

For both types of production, the embossment can be produced both in one stage and in several stages via a plurality of embossing rollers or sets of punches provided one after the other in the direction of production.

In order to prevent bending of the extruded tubes during the manufacturing process, the extrusion tube is held by means of at least one holding function before and / or after the embossing stage in position. A lateral roller guide ensures that the extrusion tube does not shift in the transverse direction during the stamping process. If the deflection of the extruded tube can only be partially prevented by means of this holding function, this can be corrected by means of a subsequent working step by stretching or recalibrating the extruded tube via a further set of rollers or a press.

The production of embossing by means of rolling has the advantage that the process can be carried out with continuous feed of the extruded tube, while for the production by means of stamp sets usually a clocking of the feed is necessary.

1. a) Der Abstand der Einprägungen ist so groß, dass eine Trennung der Strangpressrohre möglich ist.
2. b) An der Trennstelle werden die Prägungen ausgesetzt.

In order to be able to optimally add the extruded tubes to the soil later, it is important that there are no characteristics and / or a change in cross section of the extruded tube in the region of the profile separation. This can be achieved in several ways:

1. a) The distance of the impressions is so large that a separation of the extruded tubes is possible.
2. b) The imprints are exposed at the separation point.

The latter can be provided for the embossing by means of rollers, for example by a corresponding geometry of the embossing roller. In this case, the roll circumference always corresponds to an integer multiple of the later profile length. Another way to provide a sufficiently wide sawing or joining area is to perform the delivery of the rollers variable, so that depending on the delivery of the rolls either imprints are formed or not.

A further advantage of production by means of rollers is that different profile variants can be produced by exchanging the rollers in a very simple way with the same production line.

In addition to an exchange of the embossing rolls, it is alternatively also possible to work with only one embossing roll into which the embossing embossments are introduced in such a way that they are interchangeable. In this case, work is done with a base roll in which variable embossing sets can be used. Alternatively, it is also conceivable to draw on a base roll without or with a few forms an additional filler, which occupies the desired embossing arrangement. In both cases, working with only one roller body.

For the embossing of the extrusion press by means of stamp sets, if necessary, the stamps in the sawing and joining area must be completely or partially exposed to obtain a large sawing area, so that no or only very weak embossments are produced.

1. 1) Die Strangpressrohre werden entweder
   • in abzüglich der fertigungsbedingten Streckung beim Prägevorgang vorkonfektionierter Länge oder
   • als Stangenmaterial mit einem Vielfachen der späteren Rohrlänge, oder
   • besonders vorteilhaft als Endlosmaterial in Spulenform für den Prägevorgang bereitgestellt.
2. 2) Prägen der Strangpressrohre mittels Walzen oder Stempelsatz
3. 3) Korrektur eventuell auftretender Verbiegung mittels Streckung und/oder Kalibierwalzen -/presse
4. 4) Eventuell Trennung der Strangpressrohre
5. 5) Eventuell Biegen der Strangpressrohre
6. 6) Reinigung der Strangpressrohre.

The production process for the stamped extruded tubes is thus as follows:

1. 1) The extrusion tubes are either
   • in minus the production-related stretch during the embossing process of prefabricated length or
   • as a rod material with a multiple of the later pipe length, or
   • particularly advantageous as endless material in coil form for the embossing process provided.
2. 2) Embossing of the extruded tubes by means of rollers or stamp set
3. 3) Correction possibly occurring by means of stretching and / or calibra - / press
4. 4) Possibly separation of the extruded tubes
5. 5) If necessary, bend the extruded tubes
6. 6) Cleaning the extruded tubes.

The sequence of these steps is chosen so that they can be very easily interlinked to create a very simple and cost-effectively executable production line.

For separation of the extruded tubes:

The separation is preferably carried out by means of a saw running along with the embossing process, but can also take place in a separate sawing process following the embossing process. Alternatively, the separation of the extruded tubes can also be done by scoring and then tearing off the tubes. This has the advantage that no chips arise and no additional Säschmmiermittel is needed. As a result, depending on the application, it may be possible to completely or partially dispense with a subsequent cleaning step.

To the material:

In principle, the stamped extruded tubes can be produced with any extrudable material. Advantageous for the desired application of heat exchangers, such as exhaust gas coolers, oil coolers, coolant coolers and intercoolers, are all extrudable aluminum alloys, in particular Al alloys, in particular AlMn alloys, AlMg alloys and AlMgSi alloys.

Silizium:

Si<1% insbesondere Si<0.6%, im Besonderen Si<0.15%

Eisen:

Fe<1.2% insbesondere Fe<0.7%, im Besonderen Fe<0.35%

Kupfer:

Cu<0.5% insbesondere Cu<0.2%, im Besonderen Cu<0.1 %

Chrom

Cr<0.5%, insbesondere 0.05%<Cr<0.25%, im Besonderen 0.1%<Cr<0.25%

Magnesium

0.02%<Mg<0.5%, insbesondere 0.05%<Mg<0.3%

Zink

Zn<0.5%, insbesondere 0.05%<Zn<0.3%

Titan

Ti<0.5%, insbesondere 0.05%<Ti<0.25%

If the extruded tube is in a corrosion-critical application, eg as a gas-conveying extruder tube of an exhaust gas cooler or a low-pressure charge air cooler, corrosion tests have shown that that a particularly high corrosion resistance can be achieved by reducing impurities in the extruded material in the following proportions by mass:

Silicon:

Si <1%, in particular Si <0.6%, in particular Si <0.15%

Iron:

Fe <1.2%, in particular Fe <0.7%, in particular Fe <0.35%

Copper:

Cu <0.5%, in particular Cu <0.2%, in particular Cu <0.1%

chrome

Cr <0.5%, in particular 0.05% <Cr <0.25%, in particular 0.1% <Cr <0.25%

magnesium

0.02% <Mg <0.5%, in particular 0.05% <Mg <0.3%

zinc

Zn <0.5%, in particular 0.05% <Zn <0.3%

titanium

Ti <0.5%, in particular 0.05% <Ti <0.25%

A particularly high corrosion resistance of these extruded tubes can generally be achieved if the particle sizes measured in the extrusion direction are <250 μm, in particular <100 μm, in particular <50 μm.

To imprint depth:

The depth of the impression depends very much on the application. However, it has been shown that, particularly from the viewpoint of material thinning and the pressure loss generated by the indentation, an indentation depth of less than 75% of the clear tube height b, in particular less than 45%, in particular less than 30%, has proven to be advantageous.

To the distance of the impressions:

1. 1) In Längsrichtung bezogen auf Prägungen der einen Seitenwand 1 zu denen der anderen Seitenwand 2 zwischen dem 0-fachen und dem 10-fachen der lichten Rohrhöhe b, insbesondere zwischen dem 0-fachen und dem 6-fachen der lichten Rohrhöhe b, im Besonderen zwischen dem 0-fachen und dem 3,5-fachen der lichten Rohrhöhe b.
2. 2) In Längsrichtung bezogen auf Prägungen welche der Reduzierung der Kanalhöhe dienen zu Prägungen welche dem Ausbeulen der Stege dienen auf einer der Seitenwände zwischen dem 0-fachen und dem 8-fachen der lichten Rohrhöhe b, insbesondere zwischen dem 0-fachen und dem 6-fachen der lichten Rohrhöhe b, im Besonderen zwischen dem 0-fachen und dem 3-fachen der lichten Rohrhöhe b.

The distance between the impressions to each other is also very much dependent on the application. However, a particularly advantageous range could also be found for this:

1. 1) In the longitudinal direction based on embossments of a side wall 1 to those of the other side wall 2 between 0 times and 10 times the clear tube height b, in particular between 0 times and 6 times the clear tube height b, in particular between 0 and 3.5 times the clear tube height b.
2. 2) In the longitudinal direction with respect to embossings which reduce the channel height are used for embossing which serve the bulging of the webs on one of the side walls between 0 and 8 times the clear tube height b, in particular between 0-fold and 6 times the clear tube height b, in particular between 0 and 3 times the clear tube height b.

Length of imprints:

• Die Länge der Einprägung sollte für den Fall des Ausführungsbeispiels nach Fig. 2 zwischen 100% und 25% der Rohrbreite, insbesondere zwischen 90% und 35%, im Besonderen im Bereich zwischen 80% und 45% der Rohrbreite betragen.
• Die Länge der Einprägung sollte für den Fall des Ausführungsbeispiels nach Fig. 6 zwischen 130% und 25% der Kanalbreite, insbesondere zwischen 90% und 35%, im Besonderen im Bereich von 75% und 45% der Kanalbreite liegen.
• Die Länge der Einprägung liegt bei einem nicht gezeigten Ausführungsbeispiel zwischen 325% und 25% der Kanalbreite, insbesondere zwischen 250% und 35%, im Besonderen im Bereich von 215% und 45% der Kanalbreite.

The length of the impressions is also heavily dependent on the application. For this, however, a particularly advantageous range could be found, which is related to the tube width or channel width:

• The length of the impression should be in the case of the embodiment after Fig. 2 between 100% and 25% of the pipe width, in particular between 90% and 35%, in particular in the range between 80% and 45% of the pipe width.
• The length of the impression should be in the case of the embodiment after Fig. 6 between 130% and 25% of the channel width, in particular between 90% and 35%, in particular in the range of 75% and 45% of the channel width.
• The length of the embossment is in an embodiment not shown between 325% and 25% of the channel width, in particular between 250% and 35%, in particular in the range of 215% and 45% of the channel width.

For soldering on an external rib, eg for coolant radiator, intercooler: If an additional outer rib is applied to the embossed extruded tube, for instance in a crossflow cooler, care must be taken to ensure that the indentations in the transverse direction are not aligned, but slightly offset in order to ensure the best possible soldering of the outer rib. For this purpose, in particular in the Fig. 2.3-2.9 and Fig. 6.6 - 6.10 illustrated arrangements of impressions. For the in Fig. 6.6 - 6.10 illustrated arrangements of embossments are the distances of the same impressions in adjacent channels in the longitudinal direction advantageously designed so that they are not an integral multiple of the rib density, but either smaller or larger, particularly advantageous in the range k / 3 to n / 3 of the rib density, for k = 1,4,7,10, .. and n = 2,5,8,11, ..., so that the best possible soldering of the outer rib results.

• Als besonders bevorzugt zur Realisierung des Konzepts der Erfindung hat sich ein hydraulischer Durchmesser in einem Bereich zwischen 2 mm und 5 mm erwiesen. Die Größe dieses Bereiches realisiert - wie anhand von Fig. 8 im Einzelnen erläutert - in besonders vorteilhafter Weise eine Abwägung zwischen der Tendenz einen möglichst guten Wärmeübergang bei einem Strangpressrohr zu realisieren einerseits und der Tendenz andererseits einen Druckverlust zu reduzieren, bzw. einen akzeptablen Druckverlust bei gleichwohl gutem Wärmeübergang zu realisieren. In diesem Zusammenhang erweist sich ein hydraulischer Durchmesser im Bereich zwischen 3 mm und 3,4 mm, insbesondere zwischen 3,1 mm und 3,3 mm als weiter besonders bevorzugt. Es hat sich insbesondere in Bezug auf den letztgenannten Bereich eines hydraulischen Durchmessers zwischen 3,1 mm und 3,3 mm gezeigt, dass ein hydraulischer Durchmesser bei etwa 3,2 mm besonders zweckmäßig ist. Zwar lässt sich auch in dem genannten Bereich eine Verschmutzung des Strangpressrohrs bzw. des Wärmetauscherrohres, grundsätzlich nicht vermeiden, doch haben Versuche ergeben, dass sich in diesem Bereich eine Verschmutzung derart stabilisiert, dass auch eine Leistungsabnahme bei einem vergleichsweise geringen Niveau gehalten wird. Während in Bereichen des hydraulischen Durchmessers außerhalb der zuvor genannten Bereiche zu erwarten ist, dass ein Strangpressrohr unter Zunahme des Druckverlustes zunehmend verschmutzt je länger er betrieben wird, ist bei den zuvor genannten, bevorzugten Bereichen eines hydraulischen Durchmessers nachgewiesener Maßen davon auszugehen, dass sich ein Druckverlust auf vergleichsweise niedrigem Niveau stabilisiert. Eine etwaige suboptimale Wärmeübertragungsleistung eines Wärmeüberträgers wird nicht weiter reduziert bei weiterem Betrieb des Wärmetauschers. Bei außerhalb der zuvor genannten Bereiche eines hydraulischen Durchmessers kommt es dagegen bei weiterem Betrieb des Strömungskanals zu einer überproportionalen Zunahme des Druckverlust und schließlich im schlimmsten Fall zu einer Verblockung der Kanäle.

For advantageous embodiments of the unembossed cross sections of the extruded tubes:

• As particularly preferred for realizing the concept of the invention, a hydraulic diameter has been found in a range between 2 mm and 5 mm. The size of this area realized - as based on Fig. 8 explained in detail - in a particularly advantageous manner, a balance between the tendency to achieve the best possible heat transfer in an extrusion tube on the one hand and the tendency on the other hand to reduce pressure loss, or to realize an acceptable pressure drop at the same time good heat transfer. In this context, a hydraulic diameter in the range between 3 mm and 3.4 mm, in particular between 3.1 mm and 3.3 mm turns out to be particularly preferred. In particular, with respect to the latter range of hydraulic diameters between 3.1 mm and 3.3 mm, it has been found that a hydraulic diameter of about 3.2 mm is particularly useful. Although contamination of the extruded tube or of the heat exchanger tube in principle can not be avoided even in the stated range, experiments have shown that contamination in this region is stabilized in such a way that a decrease in output is maintained at a comparatively low level. While in areas of hydraulic diameter outside the previously It is to be expected that an extrusion tube becomes increasingly polluted as the pressure loss increases, the longer it is operated, it can be assumed that a pressure loss stabilizes at a comparatively low level in the abovementioned preferred ranges of a hydraulic diameter. Any suboptimal heat transfer performance of a heat exchanger will not be further reduced upon further operation of the heat exchanger. In the case of outside of the aforementioned ranges of a hydraulic diameter, on the other hand, with continued operation of the flow channel, there is a disproportionate increase in the pressure loss and, in the worst case, a blockage of the channels.

An extrusion tube according to the concept of the invention can be used advantageously both in the context of high-pressure exhaust gas recirculation and in the context of low-pressure exhaust gas recirculation. Furthermore, an application for a charge air cooling or coolant cooling is possible. In all, in particular those mentioned or similar, applications, an increase in the number of webs to improve the heat transfer according to the concept of the invention is avoided by the hydraulic diameter is selected in a range between 1.2 mm and 6 mm. However, tests have shown that a choice of a range for the hydraulic diameter optimized with regard to a low-pressure exhaust gas recirculation, high-pressure exhaust gas recirculation or intercooling can be designed differently. In high-pressure exhaust gas recirculation, it has been found that both the increase in pressure loss and the increasing risk of blocking or fouling of a channel by soot particles or the like are comparatively critical. For a high-pressure heat exchanger, a range of a hydraulic diameter between 2.5 mm and 4 mm, in particular between 2.8 mm and 3.8 mm has proven to be particularly advantageous.

In the case of a low-pressure exhaust gas recirculation concept, no or only very little soot is introduced, so that in this case it is also advantageously possible to work with a smaller hydraulic diameter than with high-pressure EGR coolers. For a low pressure heat exchanger has a Area of a hydraulic diameter between 2 mm and 3.5 mm, in particular between 2.5 mm and 3.5 mm proved to be particularly advantageous.

It has proven to be particularly advantageous, in particular for increasing corrosion resistance, to choose a ratio of a web thickness and a channel jacket thickness below the value 1.0. In other words, to increase the corrosion resistance, it is advantageous to provide the channel jacket with a thicker wall than a web. This is particularly advantageous with regard to the execution of an extruded tube, in which at least the channel jacket is manufactured based on an aluminum material.

In addition, it has proven to be fundamentally relevant to optimize a channel casing thickness such that corrosion resistance on the one hand, in particular in the case of an extruded tube based on an aluminum material, is ensured to a sufficient extent and, on the other hand, to provide a sufficient number of extruded tubes in the available installation space of a heat exchanger. In general, a space for a heat exchanger in a motor is comparatively limited, so that it is fundamentally within the scope of an improvement to provide as many extruded tubes in a heat exchanger available and thus not to design a Kanalmantelstärke too thick. According to a particularly preferred embodiment of the invention, a ratio of the hydraulic diameter and a channel shell thickness in a range between 0.8 and 9 has proven to be particularly advantageous. This area has proved to be particularly useful, especially in an extruded tube based on an aluminum material, in particular in an extruded tube in which at least the channel jacket is based on an aluminum material. Also advantageous is a range between 1.2 and 6.0, in particular a range between 1.4 and 6 with regard to the design of the channel casing thickness (space requirement, corrosion resistance) and the hydraulic diameter (heat transfer, pressure loss). The concept of the invention and / or one or more of the aforementioned developments, alone or in combination, proves to be particularly advantageous for dimensions of an extruded tube which is a ratio of an outer circumference of the extruding tube and the circumference wettable by the first fluid in a range between zero , 1 and 0.9, in particular between 0.1 and 0.5 for exhaust gas cooler realize. The investigations on the subject have shown that within the scope of the dimensions mentioned, the behavior of an extruded tube is particularly advantageous in view of the above-described problem.

Particularly expedient in terms of manufacturing aspects and the above-mentioned problem is an extruded tube proves in the pipe cross section a web is arranged as a whole web at one end and the other end on the channel jacket inside. In particular, a pipe cross-section may only have full webs. Advantageously, a whole web is continuous, without openings, executed between a first channel jacket inner side and a second channel jacket inner side. As an example Figs. 9A and 9B explained, can thereby realize an extrusion tube with a hydraulic diameter according to the concept of the invention.

In addition, an extruded tube has proved to be advantageous in which a web is arranged as a partial web in the tube cross-section only one end of the channel inside and the other freely protrudes into the interior. As exemplified by 10A and 10B such as FIGS. 11A and 11B explained, can be realized on the basis of an extruded flow channel in a particularly advantageous manner, a hydraulic diameter according to the concept of the invention.

It has been found that advantageously two partial webs can be arranged with end faces lying opposite one another. Alternatively or in combination with the above-mentioned arrangement of partial webs, two partial webs may be arranged with mutually laterally offset end faces. Preferably, a partial web and a whole web are alternately arranged next to one another.

It has proven to be particularly advantageous to make dimensions and arrangements of the partial webs as follows. According to a particularly preferred embodiment, a ratio of a distance between two part-standing, in particular two opposite partial webs and / or two mutually offset partial webs, to a height of the pipe cross section in a range below 0.8, preferably in a range of 0.3 and 0.7. Preferably, a ratio of a distance of a first partial web to a full web to a distance of a second partial web to the full web, in a range between 0.5 and 1.0, preferably in a range between 0.6 and 0.8.

Fig. 8 represents the ratio of the volume wetted by a fluid, such as exhaust gas, and an outer circumference of the extruding tube as a function of the hydraulic diameter. A preferred ratio results from the hatched areas of a preferred hydraulic diameter of 2 mm to 5 mm, in particular 2, explained above , 8 mm to 3.8 mm. Out Fig. 8 It can be seen that said ratio should be in the range between 0.1 and 0.5 in order to achieve improved degrees of exchange and pressure loss. Fig. 8 is an example of an in 10B specified profile of an extrusion tube at-exemplified. A comparable tendency can be observed even in the case of the further constructive embodiments of a flow-through cross-section described below in more detail in the case of an extruded tube. So shows Fig. 8 the explained ratio for different web distances a, including the Fig. 10B , (present for two examples a = 2 mm and a = 5 mm) and for different values of a ratio of a distance between two opposing partial webs to a height of the tube cross-section, which is designated herein k. The ratio k should be as in Fig. 8 represented by arrows, in a range below 0.8, preferably in a range between 0.3 and 0.7. In the present case, the ratio k of a distance e between two opposing partial webs to a height b of the pipe cross-section increases from 0.25 to 0.75 in the direction of the arrow. This analysis applies both to an exhaust gas cooler in the context of a high-pressure design in an exhaust gas recirculation system and to an exhaust gas cooler in the context of a low-pressure design in an exhaust gas recirculation system.

The following will be FIGS. 9A to 11B exemplary constructive embodiments of a cross section of different preferred extrusion tubes described. It should nevertheless be clear that modifications thereof as well as any combination of features of the concretely described in the figures embodiments are possible and yet a hydraulic diameter in the range between 1.5 mm and 6 mm, preferably between 2 mm and 5 mm, preferably between 2.8 mm and 3.8 mm can be achieved. In particular, in the embodiments shown in the following figures, a modification is shown, in which a channel shell thickness and a web thickness d are the same and a further modification is shown in which a ratio of a web thickness d and a channel shell thickness s below 1, 0 mm. Accordingly, the wall thicknesses of partial webs or similar dimensions, depending on the purpose to be achieved, vary and adapt.

Figs. 9A and 9B show two modifications of an extrusion tube 61, 61 ', wherein the modifications differ in that the shell thickness s in the in Fig. 9B shown extrusion tube 61 'is thicker than a web thickness d, while this in the in Fig. 9A shown extrusion tube 61 are substantially equal. In addition, the same reference numerals are used for the same features.

The flow channel 61, 61 'is formed as a total extruded profile, ie as an extruded channel casing together with the extruded webs. The flow channel 61, 61 'accordingly has a channel jacket 63 with an interior 67 surrounded by a channel jacket inner side 65, which in the present case is designed to heat-exchange the first fluid in the form of an exhaust gas. Furthermore, the flow channel 61, 61 'in the present case has a number of five webs 69 arranged in the inner space 67 on the channel casing inner side 65, which webs are formed together with the channel casing 63, 63' as an integral extruded profile. A web 69 extends completely parallel to a flow channel axis perpendicular to the plane of the drawing, along the flow path formed in the housing of a heat exchanger, uninterruptedly. Of the shown durchströmbare cross-section transverse to the flow channel axis is designed to guide the exhaust gas in the interior 67. The design is based on the hydraulic diameter ie, for the present extrusion tube 61, 61 'with reference to the distances a, b in the lower right in Fig. 9B is specified. The hydraulic diameter is given as four times the ratio of the area of the flow-through cross-section to a wettable by the exhaust gas perimeter. The area of the flow-through cross section is presently a multiple of the product of a and b. The wettable circumference here is also the multiple of twice the sum of a and b. a indicates the width of the free cross section of a flow line 74 subdivided by the webs 69 in the flow channel, and b indicates the free height of the streamline 74 in the present case.

In this flow channel 63, 63 'as well as in the following flow channels explained in more detail, a wall thickness s in the range between 0.2 mm and 2 mm, for corrosion-critical applications preferably in the range between 0.5 mm and 1.4 mm, for corrosion-critical applications preferably in the range between 0.3 mm and 0.8 mm. A height b of a flow thread 74 or a height of the inner space 67 in the present case is in the range between 2.5 mm and 10 mm, preferably in the range between 4.5 mm and 7.5 mm. A width a of a channel 74 in the transverse direction is in the range between 3 mm and 10 mm, preferably in the range between 4 mm and 6 mm.

10A.2 and 10B.2 show two further modifications of a particularly preferred embodiment of an extrusion tube 71, 71 ', which - as explained above - differ only in the wall thickness of the channel jacket 73, 73' relative to the wall thickness of a web 79. The flow channel 71, 71 'also has the webs 79 in the form of full webs and next to them alternately to the full webs 79 arranged partial webs 79'. The extrusion tube 71, 71 'is in turn formed entirely as an extruded profile, wherein a channel 74 is again formed by the distance between two full webs 79. The hydraulic diameter of the permeable cross section at the in 10A and 10B shown extrusion tubes 71,

71 'is below Fig. 10B specified. In the present case two partial webs 79 'are arranged with opposite end faces 76.

In Fig. 11A.2 and Fig. 11B.2 two further modifications 81, 81 'of a particularly preferred embodiment of an extrusion tube 81, 81' are shown, in which two partial webs 89 'are arranged with end faces 86 offset laterally from one another. A hydraulic diameter ie for the profile shown again results from the below Fig. 10B shown formula, where a1 is replaced by a4.

A ratio of a distance a3 of a first partial web 89 'to a full web 89 to a distance a4 of a second partial web 89' to the whole web 89 is in a range between 0.5 mm and 1.0 mm, preferably in a range between 0.6 mm and 0.8 mm. In principle, the distance e between two opposite partial webs 79 'and / or between two mutually offset partial webs 89' to a height b of the tube cross-section in a range below 0.8 mm, in particular in a range between 0.3 mm and 0.7 mm.

Each of the in FIGS. 9A to 11B shown preferred extruded tubes according to the invention with indentations and bulges according to the illustrated embodiments provided to optimize the turbulence and the heat transfer and the pressure drop in the concrete application.

In particular for the in 10A, 10B . 11A and 11B Extruded profiles shown in addition to the described procedure for embossing the pipe wall and the pipe webs, an embodiment with exclusive buckling of the solid and semi-webs is advantageous. Due to the large number of webs and / or the length of the half-webs an impression of the pipe wall can lead to a blocking of the flow channel by contacting or almost touching half-webs. Therefore, it depends on the distance e, in particular for the in 10A, 10B and 11A, 11B Profiles shown often cheaper, only the webs and and half-bridges by targeted impressions in the vicinity of the web approaches to buckle and the Pipe walls only as little as possible. This is especially true for e <1 / 3b.

FIGS. 12 and 13 show each other versions 91, 101 of cross sections of not bulged extruded tubes. There are in each case partial webs 92, 102 which extend transversely into the channels 6, starting from the webs 5. In the example below Fig. 12 the partial webs are each arranged at the same height and in the example according to Fig. 13 at different heights.

The pictures after FIGS. 12 and 13 are true to scale, so that they can be taken from certain dimensions of the drawn dimensions.

It is understood that the individual features of the various embodiments can be combined depending on the requirements.

Claims (12)

1. An extruded tube for a heat exchanger, comprising two at least approximately parallel outer side walls (1, 2), which extend in a longitudinal direction (z) and a transverse direction (y) of the extruded tube and are connected by means of two outer narrow sides (3, 4) in a vertical direction (x) of the extruded tube, whereby at least two continuous webs (5) extend between the side walls (1, 2) in the longitudinal direction (z) and in the vertical direction (x) and separate at least three channels (6) of the extruded tube, and whereby at least one of the outer side walls (1, 2) has impressions (7), by means of which both bulges of the side walls (1, 2), said bulges projecting into the channels (6), and bulges of the webs (5), said bulges extending substantially in the transverse direction (y), are formed, characterized in that the bulges of at least one of the at least two webs (5) has a controlled orientation relative to the transverse direction (y), whereby at least one of the impressions (7) has an elongate form, whereby a plurality of webs (5) are coincident with and bulged by the same impression (7), and the elongate impression (7) has an orientation angle to the transverse direction (y), whereby the orientation angle is approximately between 0° and 45°, in particular approximately between 20° and 45°, in particular approximately between 28° and 42°.
2. The extruded tube according to claim 1, characterized in that at least one of the channels (6) of the extruded tube in the longitudinal direction (x) has a regular, wave-shaped course in regard to the transverse direction (y).
3. The extruded tube according to any one of the preceding claims, characterized in that a distance in the transverse direction (y) between two neighboring webs (5) is substantially constant.
4. The extruded tube according to any one of the preceding claims, characterized in that at least one of the impressions (7) coincides substantially only with the at least one web (5).
5. The extruded tube according to any one of the preceding claims, characterized in that at least one of the impressions (7) does not coincide with a web (5).
6. The extruded tube according to claim 5, characterized in that the impression (7) has an orientation opposite to the transverse direction (y).
7. The extruded tube according to claim 6, characterized in that an orientation angle of the impression (7) relative to the transverse direction (y) is approximately between 0° and 45°, particularly approximately between 25° and 45°, particularly approximately between 30° and 40°.
8. The extruded tube according to any one of the preceding claims, characterized in that at least one of the impressions (7) is made winglet-shaped, such as elongated [winglets].
9. The extruded tube according to claim 7, characterized in that the winglet-shaped impression (7) has a length-to-width ratio of between 1.2 and 5, preferably between 2 and 5, especially preferably between 2.5 and 3.2, or preferably between 1.5 and 3, especially preferably between 1.8 and 2.5.
10. The extruded tube according to any one of the preceding claims, characterized in that the orientations of at least some bulges of neighboring webs (5), which are substantially at the same height in the longitudinal direction, are the same.
11. A heat exchanger for a motor vehicle, comprising an extruded tube according to any one of the preceding claims.
12. A method for producing an extruded tube according to any one of claims 1 through 11, comprising the steps

    - production of the extruded tube by an extrusion process, and subsequently

    - impression of the impressions in the side walls (1, 2).

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