EP1630513B1 - Flat tube for heat exchanger, in particular for vehicles and method for producing the same - Google Patents

Description

The invention relates to a method for producing a flat tube according to claim 1. EP 1 060 808 discloses a method for producing a flat tube from a sheet-metal strip with inward embossments, so-called turbulators, and at least two chambers, wherein first a flat sheet metal strip is provided and fed to a tube forming machine, wherein the embossments are formed in one or more stages from the sheet metal strip, and wherein at the longitudinal edges of the sheet metal head radii are formed. 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 arranged on both sides turbulators do not touch each other, 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 accordingly thick-walled. This increases the weight and the material consumption.

Trained as a multi-chamber tubes flat tubes were known by a variety of documents, eg. B. by the DE 102 01 511 A1 and the DE 102 01 512 A1 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 pipes were by the EP 0 457 470 B1 known, wherein a flat tube with opposing, soldered together nubs, which are designed as tie rods to increase the internal pressure resistance, is disclosed. However, this does not form discrete flow channels. Another multi-chamber tube was through the EP 0 637 474 A1 known, wherein the individual chambers are divided by soldered together, extending in the longitudinal direction beads. As an alternative, flat tubes are disclosed which are reinforced by knob-like tie rods. By the EP 0 302 232 A1 and the DE 102 12 300 A1 The applicant has disclosed folded and brazed multi-chamber tubes and methods for producing a folded multi-chamber tube.

On the other hand, was by the DE 101 27 084 A1 the Applicant a flat tube for a heat exchanger, in particular a coolant radiator for motor vehicles known, the flat sides of the flat tube having inward manifestations, 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 arranged at an angle to each other - they form so-called winglet pairs. A similar flat tube was through the EP 1 061 319 B1 known, also suitable for a motor vehicle radiator.

It is an object of the present invention to provide a method for producing 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.

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 can have any shape, d. H. oblong or round or angular, d. H. be designed 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. To produce a so-called folding tube is used as a starting material, a flat strip, which preferably consists of aluminum and Lotplattiert on both sides; it is fed to a tube forming machine, which converts the flat strip into flat tubes in a continuous process. First, each folds are placed on the longitudinal edges, ie edges folded approximately at right angles. Thereafter, the turbulators are molded, in a single or multi-stage, preferably two-stage process, ie, first by prefetching a preform and then stamping a final mold. 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 at the longitudinal edges, and the tube is closed so that the beads and the head radii abut each other, the head radii being preferably merged into 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 web or webs, the turbulators are then formed in the flat band, 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 pressures in a coolant circuit. In addition, the heat transfer of the coolant is improved in the tube, 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 nicht erfindungsgemäßes 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

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

Fig. 6a - 6f

nicht erfindungsgemäße 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 non-inventive 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 a central web and a lateral 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

not inventive method steps for producing a folding tube according to Fig. 1 with turbulators,

Fig. 6a - 6f

non-inventive method steps for producing a web tube according to Fig. 2 with turbulators,

Fig. 7a - 7f

Process steps for producing a welded bead pipe according to Fig. 3 with turbulators,

Fig. 8a - 8f

Process steps for producing a welded bar 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 non-inventive flat tube, which is designed as a so-called folding tube with a arranged in the middle fold 2, softer the flat tube 1 divided 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 1c, 1d. 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 designed as impressions projecting into the interior of the flat tube and are formed by the prior art, in particular the DE 101 27 084 A1 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 pipe 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. Same parts are here with the same reference numbers as in Fig. 1 that is, 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 1c - in this area, the edges of the flat strip curved to radii overlap 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 Fig. 1 used. 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 1 a, 1 b are indicated by dashed lines 5 a, 5 b, 5 c, 5 d. A manufacture of the welded bead pipe 9 will be described below.

Fig. 4 shows a two-pipe 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 1c. Otherwise, the two-chamber tube 13 corresponds to those of the previous embodiments and carries the same reference numerals for the same parts. 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.

The FIGS. 5a to 5f show individual, non-inventive method steps for producing a seaming tube with a central web, as in Fig. 1 is shown. 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. Fig. 5a shows a flat belt 16, which - after a first process step - at its longitudinal edges perpendicularly erected folds 17, 18, which is carried out by the machine, not shown by single or multi-stage roll forming. In a next process step, shown in Fig. 5b , Vorformen 19 are preferred by turbulators in a first stage, ie formed from the flat strip 16. In a second stage, shown in Fig. 5c , Formed 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. Due to the two-stage deformation process for the manufacture of the turbulators 20 results in the desired shape of the turbulators without it a substantial change in the material thickness of the flat strip 16 comes. The turbulators 20 are distributed across 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 Fig. 5d - Be bent to so-called head radii 23, 24. 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 bottom of the tube to be manufactured is arranged. Fig. 5f shows finally 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. soldered in the production of a block, not shown, for a heat exchanger and is therefore sealed. At the same time, the fold 17, 18 acts as a tie rod. The turbulators 20, which are in the flat areas of the pipe wall are embossed, 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, not inventive steps the production of a folding tube, as shown in Fig. 2 is shown, ie with a laterally arranged in the region of the narrow side fold. Fig. 6a shows a flat strip 26 after a first process 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 be done in several stages. Fig. 6b shows the flat strip 26 after a further process step in which - also in several stages - at both longitudinal edges head radii 28, 29 were formed. In a next process step - shown in Fig. 6c - Turbulators are preferred, that is, 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 process step - shown in Fig. 6d - The final shape of the turbulators 31 is produced by counter-stamping. In a next process 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 beading tube, as in Fig. 3 is shown. The starting material is again a ribbon 34, from which in a first process step - shown in Fig. 7a Preform 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 process step, namely the counter-stamping, which brings the turbulators 36 in its final shape. The next step in the process is to form two beads 37, 38 in the flat strip 34 symmetrically to the center line m, which in Fig. 7c are shown. 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. Fig. 7f shows the closed bead tube 42. Both tube halves are brought together so that the head radii 39, 40 butt together and form a butt joint, which is closed with a longitudinal weld 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 in Fig. 4 is shown. Starting material is again a flat band 44, in which first a web 45, preferably formed in several stages - 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 drawing. Subsequently, the turbulators 47 are brought into their final shape by countermolding. Fig. 8d shows the forming of head radii 48, 49 on the edge sides of the flat band 44th Fig. 8e shows the process step "tube closing", wherein in the region of the center line m a radius 50 is bent into the flat band 44. Fig. 8f shows the finished web tube 51, which is closed by a weld 52 in the region of the butt-headed head radii 48, 49. The web 45 does not contact the opposite side of the tube 51, since this flat side is still crowned. It is leveled later, then contacted the web 45 with its web back the opposite side and is soldered to this.

Fig. 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 section of a pipe belt 56, in which turbulators 57, 58 after the top to Fig. 9 are formed described method. 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 above DE 101 27 084 A1 the applicant is known. 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 belt 59 with a turbulator 60, which is formed in the shape of a truncated pyramid and is formed from the pipe band 59. An adjacent section BB shows the profile of the turbulator 60.

Fig. 12 shows a section of a pipe belt 61 with a further embodiment of a turbulator 62, which is frusto-conical. 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 (17)

1. A method for the production of a flat tube from a sheet metal band, with inward-looking impressions (36, 47), so-called turbulators, and at least two chambers (3, 4) which are respectively divided by a separating wall (37/38, 45) formed from the sheet metal band, wherein

   a) first, a flat sheet metal band is provided and supplied to a tube forming machine,

   b) the separating wall is formed as web, fold or bead from the sheet metal band in one or more steps,

   c) the impressions are formed from the sheet metal band in one or more steps,

   d) head radiuses are formed on the longitudinal edges of the sheet metal band, and

   e) a cross-section of the flat tube is closed by forming a rounded narrow side,

   wherein step d) is performed subsequently to step c).
2. The method according to claim 1, characterised in that step b) is performed before step c).
3. The method according to claim 1, characterised in that step b) is performed subsequently to step c).
4. The method according to claim 3, characterised in that step b) is performed before step d).
5. The method according to one of the preceding claims, characterised in that one or more webs are formed as separating wall.
6. The method according to one of claims 1 to 4, characterised in that one or more folds are formed as separating wall.
7. The method according to one of claims 1 to 4, characterised in that one or more beads are formed as separating wall.
8. The method according to one of the preceding claims, characterised in that the impressions are formed from the sheet metal band on both sides of the separating wall.
9. The method according to one of the preceding claims, characterised in that a rounded narrow side is formed on the cross-section of the flat tube.
10. The method according to one of the preceding claims, characterised in that the head radiuses (48, 49; 39, 40) are joined to a butt joint and in that the flat tube (51, 42) is closed by a longitudinal welding seam (52, 43) in the region of the butt joint.
11. The method according to one of claims 1 to 9, characterised in that the head radiuses (28, 29) are joined to an overlapping fold (28/29) and in that the flat tube (33) is soldered in the region of the overlapping fold (28/29) and the separating wall (27).
12. The method according to one of the preceding claims, characterised in that the impressions are produced by rolling the flat band (53).
13. The method according to one of the preceding claims, characterised in that the impressions are first brought forward and then counter-punched.
14. The method according to one of the preceding claims, characterised in that the impressions are formed on both flat sides (1a, 1b) of the flat tube, wherein a clear height h is left between them for each flow channel.
15. The method according to one of the preceding claims, characterised in that the impressions are formed in a longitudinal (57, 58) or angular (60) or round (62) way.
16. The method according to one of the preceding claims, characterised in that the impressions are formed distributed all over the flat region of each chamber (3, 4).
17. The method according to one of the preceding claims, characterised in that the impressions are formed and arranged as so-called winglets (57, 58).

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