EP1630513A2 - Flat tube for heat exchanger, in particular for vehicles and method for producing the same - Google Patents

Abstract

The flat tube (1) is produced from one piece of strip. It has a turbulence creators (5a, 5b, 5c, 5d) stamped into it, facing inwards. The flat tube is in the form of a multi-chamber to one it has at least two chambers (3, 4), which are separated by a partition wall (2) formed from the single piece of strip from which the tube is made.

Description

The invention relates to a flat tube for a heat exchanger, in particular for motor vehicles according to the preamble of claim 1 and a method for producing a flat tube according to the preamble of claim 10.

It is known to produce flat tubes for heat exchangers from a sheet-metal strip, preferably from a double-side solder-plated aluminum strip in a continuous process on a corresponding pipe-making machine. After bending and forming the flat tube cross-section, the flat tube is closed by a welded or soldered longitudinal seam. Such flat tubes are z. B. used for coolant radiator in motor vehicles, the flat tubes are joined with corrugated ribs to form a block and soldered. In order to achieve the lowest possible air-side pressure drop, the flat tube cross-sections are formed as slim as possible, to increase the internal pressure resistance webs, folds or beads are provided which act as tie rods and divide the flat tube cross-section into chambers. Also known are flat tubes, which are not designed as multi-chamber tubes, but have a continuous cross-section, wherein to increase the heat transfer to the inside of the tube, ie, for. B. on the coolant side so-called turbulators or vortex generators are provided in the form of inwardly directed impressions. These turbulators on both sides touch each other not, but leave between them a distance, ie a clear channel height for a core flow; they do not act as tie rods. In order to achieve the necessary internal pressure resistance of such flat tubes, these tubes must be designed thick-walled accordingly. This increases the weight and the material consumption.

Trained as a multi-chamber tubes flat tubes were known by a variety of documents, eg. Example, by DE 102 01 511 A1 and DE 102 01 512 A1 of the applicant as welded multi-chamber tubes, in which the individual chambers are separated by a web, which is formed from the flat strip. On the narrow side, the pipes are closed by a longitudinal weld. Similar but modified multi-chamber tubes have been disclosed by EP 0 457 470 B1, whereby a flat tube with opposing studs soldered to each other, which are designed as tie rods to increase the internal pressure resistance, is also disclosed. However, this does not form discrete flow channels. Another multi-chamber tube was known from EP 0 637 474 A1, wherein the individual chambers are divided by brazed together, extending in the longitudinal direction beads. As an alternative, flat tubes are disclosed which are reinforced by knob-like tie rods. EP 0 302 232 A1 and DE 102 12 300 A1 of the Applicant have disclosed folded and brazed multi-chamber tubes and methods for producing a folded multi-chamber tube.

On the other hand, DE 101 27 084 A1 of the applicant has disclosed a flat tube for a heat exchanger, in particular a coolant radiator for motor vehicles, wherein the flat sides of the flat tube have inwardly directed forms, so-called vortex generators or turbulators. This achieves improved heat transfer of the coolant flowing through the flat tubes. However, these flat tubes are not designed as multi-chamber tubes and also have no tie rods, z. B. from each other soldered nubs. It is therefore necessary to form these tubes thick-walled in order to achieve the required internal pressure resistance. The turbulators are preferably formed as elongated impressions, which are arranged in rows transversely to the flow direction and in Angle to each other are arranged - they form so-called winglet pairs. A similar flat tube was known from EP 1 061 319 B1, also usable for a motor vehicle radiator.

It is an object of the present invention to provide a flat tube of the type mentioned, which on the one hand has a high internal pressure resistance and on the other hand, a high heat transfer on the tube inside. It is also an object of the invention to provide a method for producing such a flat tube.

This object is initially achieved by the features of claim 1. According to the invention it is provided that a flat tube equipped with turbulators is designed as a multi-chamber tube, d. H. Has at least two chambers which are separated from each other by a partition wall. Thus, the advantage is achieved that, on the one hand, an improved heat transfer takes place on the inside of the pipe and, on the other hand, an increased internal pressure rigidity, combined with a reduced material thickness (pipe wall thickness), is provided. The turbulators are preferably arranged on both flat sides of the flat tube in each chamber. The partitions may advantageously be formed as a web, fold or beads, and the flat tubes are advantageously longitudinal seam welded or soldered by means of a fold.

In an advantageous embodiment of the invention, the turbulators may have any shapes, ie be elongated or round or angular, ie knob-shaped or truncated pyramid, as is already known from the prior art. The turbulators extend into the interior of the pipe only so far that a clear channel height is maintained for an undisturbed core flow. This provides the advantage that on the one hand the heat transfer improves, but the pressure drop is not excessively increased. The turbulators are preferably arranged only on the flat areas of the longitudinal sides and preferably designed as so-called winglets, which represent an optimum between heat transfer and pressure drop.

The object of the invention is also solved by the features of claim 10 and the independent method claims 11 and 12. For the production of a so-called seaming tube, a flat strip is used as the starting material, which preferably consists of aluminum and is solder-plated on both sides; it is fed to a tube forming machine, which converts the flat strip into flat tubes in a continuous process. First, folds are placed on the longitudinal edges, d. H. Edges about folded at right angles. Thereafter, the turbulators are formed, in a single or multi-stage, preferably two-stage process, d. H. first by advancing a preform and then stamping a final shape. Distances are left between the turbulators, seen in the width direction, within which the band remains flat and thus can be bent to make head radii. Finally, the tube is closed and soldered in the area of the fold. The latter forms the partition for a two-chamber tube, acts as a tie rod and at the same time forms the longitudinal seam of the tube.

In a further advantageous embodiment of the invention, a two- or multi-chamber tube is produced, in which the partition or the partitions are formed by beads. Starting from a flat band, the turbulators are first formed again in the flat band, preferably in a two-stage process, and then beads are formed between the turbulators. Thereafter, head radii are formed on the longitudinal edges, and the tube is closed so that the beads and the head radii abut each other, wherein the head radii are preferably brought together in a butt joint, which is longitudinally welded. The beads solder - when soldering a heat exchanger block - and thus form tie rods and one or more dense partitions.

In a further advantageous embodiment of the invention, a folding tube is produced by a similar method, which in turn starts from a flat strip and initially forms at least one web which is formed in one or more forming steps out of the flat strip. On both sides of the bridge or the webs are then the turbulators in formed the ribbon, then head radii are formed on the longitudinal edges, which are finally combined to form a butt joint, which is preferably longitudinally welded. The bridge soldered to the opposite flat side.

According to a further advantageous embodiment of the invention, the head radii are shaped such that when closing the flat tube forms a lap joint or edge-side fold, which can be soldered. This eliminates the welding process.

In a further advantageous embodiment of the invention, the turbulators are produced in a continuous process, d. H. by rolling, wherein the flat strip is passed through a pair of rollers, which has the shape of the turbulators as a die and male.

According to a further advantageous embodiment of the invention, the flat tube is used for a motor vehicle heat exchanger, in particular a coolant radiator, which has a brazed block, which consists of flat tubes and corrugated fins. The flat soldered on both sides flat tube can be easily soldered to the corrugated ribs in a block. The high degree of slenderness of the flat tube ensures a low air-side pressure drop, on the other hand is given by the partitions in the form of webs, folds or beads the required internal pressure resistance, which is adapted to the prevailing in a coolant circuit pressures. In addition, the heat transfer of the coolant in the tube is improved, d. H. the cooling capacity of the radiator is increased without the pressure drop, d. H. the pump capacity increases considerably. This is a lighter and more powerful cooler for motor vehicles to produce.

Fig. 1

ein als Falzrohr ausgebildetes Flachrohr (Zweikammerrohr) mit mittlerem Falz,

Fig. 2

ein als Falzrohr ausgebildetes Flachrohr (Zweikammerrohr) mit mittlerem Steg und seitlichem Falz,

Fig. 3

ein als geschweißtes Sickenrohr ausgebildetes Flachrohr (Zweikammerrohr),

Fig. 4

ein als geschweißtes Stegrohr ausgebildetes Flachrohr (Zweikammerrohr),

Fig. 5a - 5f

Verfahrensschritte zur Herstellung eines Falzrohres gemäß Fig. 1 mit Turbulatoren,

Fig. 6a - 6f

Verfahrensschritte zur Herstellung eines Stegrohres gemäß Fig. 2 mit Turbulatoren,

Fig. 7a - 7f

Verfahrensschritte zur Herstellung eines geschweißtes Sickenrohres gemäß Fig. 3 mit Turbulatoren,

Fig. 8a - 8f

Verfahrensschritte zur Herstellung eines geschweißtes Stegrohres gemäß Fig. 4 mit Turbulatoren,

Fig. 9

ein Walzenpaar zur Einformung von Turbulatoren in ein Flachband,

Fig. 10

einen Ausschnitt eines Flachrohres mit als winglets ausgebildeten Turbulatoren,

Fig. 11

einen Ausschnitt eines Flachrohres mit als Pyramidenstumpf ausgebildeten Turbulatoren und

Fig. 12

einen Ausschnitt eines Flachrohres mit kegelstumpfförmigen Turbulatoren (Noppen).

Embodiments of the invention are illustrated in the drawings and will be explained in more detail below. Show it

Fig. 1

a flat tube (two-chamber tube) with a middle fold formed as a folding tube,

Fig. 2

a flat tube designed as folding tube (two-chamber tube) with middle bridge and side fold,

Fig. 3

a flat tube designed as a welded bead tube (two-chamber tube),

Fig. 4

a flat tube designed as a welded bar tube (two-chamber tube),

Fig. 5a - 5f

Method steps for producing a folding tube according to FIG. 1 with turbulators,

Fig. 6a - 6f

Method steps for producing a web tube according to FIG. 2 with turbulators,

Fig. 7a - 7f

Process steps for producing a welded bead tube according to FIG. 3 with turbulators,

Fig. 8a - 8f

Method steps for producing a welded bar tube according to FIG. 4 with turbulators,

Fig. 9

a pair of rollers for forming turbulators in a flat band,

Fig. 10

a section of a flat tube with trained as winglets turbulators,

Fig. 11

a section of a flat tube with designed as a truncated pyramid turbulators and

Fig. 12

a section of a flat tube with frustoconical turbulators (nubs).

Fig. 1 shows a schematic representation of a cross section through a flat tube, which is designed as a so-called folding tube with a fold 2 arranged in the middle, which divides the flat tube 1 into two chambers 3, 4. The cross section of the flat tube 1 is composed of two flat sides 1a, 1b and two rounded narrow sides 1 c, 1 d together. In the two chambers 3, 4 dashed contours 5a, 5b, 5c, 5d are shown by turbulators. Between each turbulators 5 a, 5 c and 5 b, 5 d, a clear channel height h is left, which is free of turbulators. The turbulators 5a, 5b, 5c, 5d are vortex generators, which are formed as projecting into the interior of the flat tube indentations and through the prior art, in particular the DE 101 27 084 A1 of the applicant, known per se. The folding tube 1 is preferably made of a double-sided solder-plated aluminum sheet, a so-called flat strip or tube tape and soldered in the region of the middle fold 2. A method of manufacturing the folding tube 1 will be described below.

FIG. 2 shows a two-chamber tube designed as a folding tube 6 with a central partition wall 7, which is designed as a web. Identical parts are here designated by the same reference numbers as in FIG. 1, ie the flat sides 1a, 1b and the rounded narrow sides 1c, 1d; as well as the chambers 3, 4 and the dashed lines contours 5a, 5b, 5c, 5d for the turbulators, which extend within a chamber 3, 4 over a width b, which is part of the flat sides 1a, 1b. The section b ends so on the one hand in front of the central web 7 and on the other hand before the rounding of the narrow sides 1c, 1d. The folding tube 2 is closed by a fold 8, which is arranged in the region of the narrow side 1 c - in this area, the edges of the flat band curved to form radii and form the solderable fold 8. The production of the folding tube 6 will be explained below.

Fig. 3 shows a so-called bead tube 9 formed two-chamber tube, which is welded in the region of a narrow side 1c by a longitudinal seam 10. Again, the same reference numerals as in Fig. 1 are used for the same parts. In the two flat sides 1a, 1b beads 11, 12 are formed, which form a partition by soldering and divide the tube into two chambers 3, 4. The turbulators formed as impressions in the flat sides 1a, 1b are indicated by dashed lines 5a, 5b, 5c, 5d. A manufacture of the welded bead pipe 9 will be described below.

FIG. 4 shows a two-chamber tube designed as a welded bar tube 13, which has a central web 14 and a weld seam 15 indicated in the region of the narrow side 1 c. Otherwise, the two-chamber tube 13 corresponds to those of the previous embodiments and contributes for same parts the same reference numbers. A method of manufacturing the welded bar tube 13 will be explained below.

Deviating from the illustrated embodiments, which show two-chamber tubes, flat tubes are also possible with a plurality of partitions formed as a fold, web and / or beads, d. H. with more than two chambers.

FIGS. 5a to 5f show individual method steps for producing a middle web seaming seam, as shown in FIG. The starting material for the production of the finished flat tube is a flat strip made of aluminum, which is solder-plated on both sides and is continuously fed to a machine, not shown, for tube production. 5a shows a flat strip 16 which, after a first method step, has folds 17, 18 set up at right angles at its longitudinal edges, which takes place by single-stage or multi-stage roll forming by the machine (not shown). In a next process step. shown in Fig. 5b, preforms 19 are preferred by turbulators in a first stage, ie formed from the flat strip 16. In a second stage, shown in Fig. 5c, takes place by countermolding the shapes of the final shape of the turbulators 20, which are shown in the drawing as rectangles - compared to the slightly rounder preform 19. By the two-stage deformation process for the manufacture of the turbulators 20 results the desired shape of the turbulators, without there being a significant change in the material thickness of the flat strip 16. The turbulators 20 are distributed over the width of the flat strip 16, ie from fold 17 to fold 18 in groups between which distances are left, in particular flat areas 21, 22, which in the subsequent method step - shown in Fig. 5d - to so-called head radii 23, 24 are bent. The latter form the rounded narrow sides of the flat tube. Fig. 5e shows the flat band 16 with almost finished bent head radii 23, 24, between which the continuous underside of the tube to be manufactured is arranged. Fig. 5f finally shows the finished, closed folding tube 25, in which the two folds 17, 18 come to lie parallel to each other and in the middle. The folding tube 25 will later, z. B. in the manufacture of a block, not shown for a Heat exchanger soldered and is therefore tight. At the same time, the fold 17, 18 acts as a tie rod. The turbulators 20, which are embossed in the flat areas of the pipe wall, project into the free flow cross-sections and thus act as a vortex generator to increase the heat transfer.

FIGS. 6a to 6f show in individual process steps the production of a folding tube, as shown in FIG. 2, ie with a fold arranged laterally in the region of the narrow side. 6a shows a flat strip 26 after a first method step in which a web 27 has been formed, ie the flat strip 26 is formed in the region of the web 27, which can take place in several stages. FIG. 6b shows the flat strip 26 after a further method step, in which - also in several stages - head radii 28, 29 have been formed on both longitudinal edges. In a next method step - shown in Fig. 6c - turbulators are preferred, ie it is a preform 30, which is formed nub-shaped or conical, produced in a first deformation stage. In the process, flat areas are left at the locations where radii are later bent for the narrow side of the pipe. This is the case here in the area of a center line m. In a further method step - shown in Fig. 6d - the final shape of the turbulators 31 is produced by counter-stamping. In a next method step - shown in Fig. 6e - the flat strip 26 is closed to a tube, that is bent in the region of the center line m to a radius 32, which forms the later narrow side of the tube. Fig. 6f shows the finished, ie closed web tube 33, in which the two head radii 28, 29 overlap over a range of about 180 degrees, which is soldered later. Thus, the flat tube 33 is sealed and obtained by the soldering of the web 27 with the opposite side and a tie rod. The turbulators 31 protrude inwards into the two flow channels of the two-chamber tube 33.

FIGS. 7a to 7f show, in several process steps, the production of a welded bead tube, as shown in FIG. Starting material in turn is a flat band 34, from which in a first method step - shown in Fig. 7a - preforms 35 of the turbulators are made, in four groups, between which, symmetrical to a center line m, leave clearances with flat areas of the flat belt 34 are. FIG. 7b shows the flat strip after the next method step, namely the counterstamping, which brings the turbulators 36 into their final shape. The next method step is to form two beads 37, 38 in the flat strip 34 symmetrically to the center line m, which are shown in FIG. 7c. Subsequently, as the next method step, the forming of head radii 39, 40 on the edge sides of the flat strip 34, which are placed in a quarter circle. Fig. 7e shows the closing of the tube, wherein in the region of the center line m a radius 41 is bent. 7f shows the closed bead tube 42. Both tube halves are brought together so that the head radii 39, 40 butt against each other and form a butt joint, which is closed by a longitudinal weld seam 43. The two beads 37, 38 are directly opposite each other, but do not touch each other in the drawing. The beading combs are later contacted during leveling and soldering of the bead pipes.

FIGS. 8a to 8f show, in individual process steps, the production of a welded bar tube, as shown in FIG. The starting material in turn is a flat band 44, in which first a web 45, preferably in several stages is formed - shown in Fig. 8a. In this case, the web 45 is arranged eccentrically to the center line m and in the middle of half the bandwidth. Fig. 8b shows preforms 46 for the turbulators made by overriding. Subsequently, the turbulators 47 are brought into their final shape by countermolding. FIG. 8d shows the shaping of head radii 48, 49 on the edge sides of the flat strip 44. FIG. 8e shows the "pipe closing" step, wherein a radius 50 is bent into the flat strip 44 in the region of the center line m. FIG. 8f shows the finished web tube 51, which is closed by a weld seam 52 in the region of the head blanks 48, 49 which are guided towards each other in a blunt manner. The web 45 does not contact the opposite side of the tube 51 yet, since this flat side is still spherical. It is leveled later, then contacted the web 45 with its web back the opposite side and is soldered to this.

9 shows the manufacturing process for embossing turbulators. A pipe belt 53 is fed to a pair of rollers 54, 55 and, after passing through the pair of rollers, receives the desired embossing of the turbulators. For this purpose, the upper roller 54 distributed on the circumference arranged projections (male) 54a, while the lower roller 55 corresponding depressions (matrices) 55a, also distributed over the circumference. The pipe band 53 is thus pressed by the elevations 54a in the recesses 55a.

FIG. 10 shows a detail of a pipe band 56 into which turbulators 57, 58 are formed according to the method described above with reference to FIG. 9. Both turbulators 57, 58 are formed as elongated shapes and V-shaped to each other, they form a so-called winglet pair, as is known from the aforementioned DE 101 27 084 A1 of the Applicant. The flow direction of the flow medium within the flat tube, that is, for example, a coolant is represented by an arrow S. A laterally arranged section AA shows the inwardly (into the tube interior) directed, approximately trapezoidal profile of the winglets 57, 58th

FIG. 11 shows a further section of a pipe band 59 with a turbulator 60, which has the shape of a truncated pyramid and is shaped out of the pipe band 59. An adjacent section BB shows the profile of the turbulator 60.

FIG. 12 shows a detail of a pipe band 61 with a further embodiment for a turbulator 62 which is of frusto-conical shape. A section CC shows the profile of the turbulator 62.

The flat tubes described above are preferably used for heat exchangers in motor vehicles, in particular coolant radiator. The latter have a soldered block, which consists of flat tubes and arranged between them corrugated fins. The flat tubes are thus flowed through by the coolant of a cooling circuit of an internal combustion engine of the motor vehicle, while the corrugated fins of ambient air be overflowed. The joining of flat tubes and corrugated ribs to a block is carried out by a so-called Kassettierprozess, in which the flat tubes are compressed by a suitable clamping device together with the corrugated fins to block size. In this case, there is also a leveling of the previously spherically formed flat sides of the flat tubes, so that folds, webs or beads come into contact with the opposite side and thus can solder.

Preferred dimensions of the flat tubes according to the invention for a coolant radiator are tube depths between 20 and 50 mm, preferably 40 mm, tube widths between 1.5 and 2 mm and wall thicknesses between 0.15 and 0.35 mm, preferably between 0.2 and 0.25 mm ,

Claims (18)

Flat tube for a heat exchanger, in particular for motor vehicles, manufacturable from a one-piece sheet metal strip, with inwardly directed embossments, so-called turbulators, characterized in that the flat tube (1, 6, 9, 13) as a multi-chamber tube, ie with at least two chambers (3 , 4) is formed, which in each case by a formed from the sheet metal strip partition (2, 7, 11/12, 14) are divided. Flat tube according to claim 1, characterized in that the flat tube (1, 6) has a brazed longitudinal seam in the form of a fold (2, 8). Flat tube according to claim 1, characterized in that the flat tube (9, 13) has a welded longitudinal seam (10, 15), preferably on the narrow side (1c). Flat tube according to claim 1, 2 or 3, characterized in that the partition wall as a web (14) and / or as a fold (2) is formed. Flat tube according to claim 1, 2 or 3, characterized in that the partition wall is formed by beads (11, 12). Flat tube according to one of claims 1 to 5, characterized in that the turbulators (5a, 5b, 5c, 5d) on both flat sides (1a, 1b) of the chambers (3, 4) are arranged and between them a clear channel height h for each flow channel left. Flat tube according to claim 6, characterized in that the turbulators are elongate (57, 58) or angular (60) or round (62). Flat tube according to claim 6 or 7, characterized in that the turbulators (5a, 5b, 5c, 5d) are distributed over the entire flat area of each chamber (3, 4). Flat tube according to claim 6, 7 or 8, characterized in that the turbulators are designed and arranged as so-called winglets (57, 58). Method for producing a flat tube according to at least one of Claims 1 to 9, characterized a) that initially a flat strip (16) is provided and fed to a tube forming machine, b) that folds (17, 18) are set up on both sides of the flat strip (16), c) the turbulators (20) are formed from the flat strip (16) in one or more stages, the turbulators (20) being arranged in groups and leaving spacings (21, 22) for head radii between the groups in the width direction, d) that the flat strip (16) in the region of the distances (21, 22) bent and the head radii (23, 24) are formed and e) that the flat tube cross-section is closed by parallel bending of the flat sides. Method for producing a flat tube according to at least one of Claims 1 to 9, characterized a) that a flat strip (26, 44) is fed to a tube forming machine, b) that at least one web (27, 45) is formed in one or more stages from the flat strip (26, 44), c) that on each side of the web (27, 45) the turbulators (31, 47) are formed in one or more stages from the flat strip (26, 44), d) that at the longitudinal edges of the flat strip (26, 44) head radii (28, 29; 48, 49) are formed and e) that the flat tube cross-section to form a rounded narrow side (32, 50) is closed. Method for producing a flat tube according to at least one of Claims 1 to 9, in particular 3 and 5, characterized in that a) that a flat belt (34) is fed to a tube forming machine, b) that the turbulators (36) are formed in one or more stages, c) that corrugations (37, 38) are formed between the turbulators (36), d) that on the longitudinal sides of the flat strip (34) head radii (39, 40) are integrally formed and e) that the flat tube cross-section is closed. A method according to claim 11 or 12, characterized in that the head radii (48, 49, 39, 40) are brought together in a butt joint and that the flat tube (51, 42) is closed in the region of the butt joint by a longitudinal weld seam (52, 43) , A method according to claim 11, characterized in that the head radii (28, 29) are brought together to form an overlapping fold (28129) and that the flat tube (33) is brazed in the region of the overlap fold (28/29) and of the at least one web (27) , Method according to one of claims 10 to 14, characterized in that the turbulators are produced by rolling the flat strip (53). Method according to one of claims 10 to 15, characterized in that the turbulators are initially preferred and then counter-stamped. Use of a flat tube according to at least one of the preceding claims in a heat exchanger with a brazed block, consisting of flat tubes and corrugated fins, in particular a coolant radiator for motor vehicles. Heat exchanger, in particular for motor vehicles, with pipes and at least one collecting box into which the pipes open, characterized in that at least one pipe according to one of claims 1 to 9 and / or produced by a method according to one of claims 10 to 16.

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