EP2020582A2 - Flat pipe for a heat exchanger - Google Patents

Abstract

Fold height and sheet thickness determine the tube width (b). Any departures of the bridging section dimensions, caused by tolerance and deformation, are accommodated by the fold height. A fold is formed from the first flat side (1a). Two folds are located adjacently and form a U-shaped gap between themselves. Bridging sections are bent from the second flat side (1b). At least one bridging section has double-layered construction and is turned over. One bridging section optionally has a fold (90[deg] ) at its terminal edge.

Description

The invention relates to a flat tube for a heat exchanger according to the preamble of claim 1.

Flat tubes for heat exchangers with at least one partition can be prepared by various methods, eg. B. by extrusion or by forming a sheet metal strip, which is closed longitudinally either by a weld or a solder seam. In soldered flat tubes, the solder seam is in the region of the partition, so that the tube is sealed on the one hand to the outside and on the other hand between the flow channels formed by the partition wall. As a solder solder plating is usually used, which is applied to the outside of the flat tube. A problem in the production of folded and brazed pipes with at least one partition wall is that the bandwidth of the metal strip to be formed is subject to tolerances, which can lead to different widths of the flat tube when forming a flat tube, for. B. if the partition is formed only by beveled at the edges of the metal strip webs. For the production of heat exchangers, however, a narrow tolerance tube width is required.

By the EP 0 302 232 A1 The applicant has been known a soldered flat tube with at least one partition, which by bevelled, to each other lying, with each other soldered webs is formed. The webs are bent over at the ends and lie on the inside of the flat tube, resulting in a dense and stable solder joint on the one hand to the outside and on the other hand also between the adjacent flow channels. Preferably, a solder plating is provided on the outside of the flat tube here.

By the US Pat. No. 5,875,668 a flat tube with a partition wall was known, which is formed by a fold and two bent webs. This creates a four-layer partition, the fold in the middle and the webs are arranged on both sides of the fold.

By the DE 198 750 510 A1 has been known a flat tube with a partition, which consists of a fold and a web, which are formed from the edge regions of the metal strip. The bridge rests on the side of the fold.

By the EP 1 213 555 B1 and the EP 1 521 050 B1 a flat tube was known with a partition, which is formed by two adjacent folds, whose ends are angled and rest on the inside of the flat tube. Both folds are made by reshaping the edge regions of the strip material from which the tube is formed.

It is an object of the present invention to design a flat tube of the type mentioned above such that tolerances (dimensional deviations) in the width of the strip material do not influence the width of the flat tube in the region of the partition wall as much as possible. It is also an object of the invention that the flat tube has a sufficient dimensional stability before the soldering process. Furthermore, the flat tube should offer the possibility that on its inside a corrosion-inhibiting coating can be applied.

The object of the invention is solved by the features of claim 1. According to the invention, it is provided that the measure of the seam height h and the sheet thickness d determine the dimension of the pipe width b and that tolerances and / or deformation-related dimensional deviations of the web dimension by the Fold height h to be recorded. Deviations of the ridge size, which result from tolerances of the bandwidth (the width of the sheet metal strip) or caused by the forming process, thus do not affect the pipe width b. The production of the seam with the seam height h is thus the starting point of the tube forming process, while the webs which are joined last are dimensioned such that they can not influence the pipe width. By forming at least one fold in conjunction with at least one web results after the forming process, a flat tube with improved inherent stability and stiffness, which prevents deformation by bending and / or torsion before the subsequent soldering or reduced.

According to a preferred embodiment, the fold or folds are formed from a first flat side of the flat tube, while the webs of the second, d. H. opposite side and the edge strip of the strip material are angled. Preferably, two folds are arranged side by side, which form a gap in which the webs are received. In this case, the webs may be single-layered or double-layered - in the latter case, they have an envelope. The webs are dimensioned so that there is always some air between the edge of the web and the inside of the flat pipe. H. a gap is left so that the ridge size can not influence the pipe width. Due to the double position of the bridge, d. H. Bridge with turn-up result for the partition six, seven or eight layers, whereby a high intrinsic stability is achieved.

According to another preferred embodiment, at least one of the webs may have an end-side bevel, which rests on the flat tube. This also results in an increase in stability.

According to a further preferred embodiment, a partition wall is provided which comprises only one fold and two webs arranged next to the fold. The webs may be single or double-layered, ie formed with an envelope, wherein the single-layer web can in turn be folded at the ends. This also makes a flat tube with a high inherent stability against deformation reached. The partition may thus comprise four, five or six layers.

According to a further preferred embodiment, a three-layer partition is provided, which is constructed only of a fold and a web, wherein both the fold and the web are formed by forming the edge strips of the strip material. Preferably, the web is enclosed by the fold, so that there is a tight soldering within the fold. For the sealing of the adjacent flow channels an internal plating is necessary so that the fold can also solder to the inside of the flat tube. Also in this solution, the advantage is achieved that the web height in conjunction with the sheet metal strip thickness determines the width of the tube and the ridge size remains without influence.

After forming the flat tubes are soldered - this is preferably a Lotplattierung on: the side of the strip material provided, which forms the outside of the flat tube. Thus, all contact mating solder the partition in the areas where at least one side is solder plated. In most embodiments of the invention, solder plating on the outside is sufficient to achieve a fluid tight connection in the partition wall area both outwardly and between the adjacent flow channels. Since no internal plating is necessary in this case, a protective plating or a corrosion-inhibiting coating can instead be made, which is advantageous for certain fluids, in particular coolants. The protective cladding is not solderable.

Preferably, the metal strip is made of an aluminum material or an aluminum alloy, which may be provided with a commercially available Lotplattierung, preferably on the outside, if necessary, also on the inside.

• Fig. 1 ein erfindungsgemäßes Flachrohr mit Trennwand,
• Fig. 1a den Trennwandbereich gemäß Fig. 1 in vergrößerter Darstellung
• Fig. 2 ein zweites Ausführungsbeispiel der Erfindung für ein Flachrohr,
• Fig. 2a den Trennwandbereich gemäß Fig. 2 in vergrößerter Darstellung,
• Fig. 3 ein drittes Ausführungsbeispiel der Erfindung für ein Flachrohr,
• Fig. 3a den Trennwandbereich gemäß Fig. 3 in vergrößerter Darstellung,
• Fig. 4 eine Darstellung des Umformprozesses für das Flachrohr,
• Fig. 5 ein viertes Ausführungsbeispiel der Erfindung für ein Flachrohr,
• Fig. 5a den Trennwandbereich gemäß Fig. 5 in vergrößerter Darstellung,
• Fig. 6 ein fünftes Ausführungsbeispiel der Erfindung für ein Flachrohr,
• Fig. 6a den Trennwandbereich gemäß Fig. 6 in vergrößerter Darstellung,
• Fig. 7 ein sechstes Ausführungsbeispiel der Erfindung für ein Flachrohr,
• Fig. 7a den Trennwandbereich gemäß Fig. 7 in vergrößerter Darstellung,
• Fig. 8 ein siebtes Ausführungsbeispiel der Erfindung für ein Flachrohr,
• Fig. 8a den Trennwandbereich gemäß Fig. 8 in vergrößerter Darstellung und
• Fig. 9 einen Rohrrippenblock in einer Draufsicht mit dem erfindungsgemäßen Flachrohr.

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

• Fig. 1 a flat tube according to the invention with a dividing wall,
• Fig. 1a the partition wall area according to Fig. 1 in an enlarged view
• Fig. 2 A second embodiment of the invention for a flat tube,
• Fig. 2a the partition wall area according to Fig. 2 in an enlarged view,
• Fig. 3 A third embodiment of the invention for a flat tube,
• Fig. 3a the partition wall area according to Fig. 3 in an enlarged view,
• Fig. 4 a representation of the forming process for the flat tube,
• Fig. 5 A fourth embodiment of the invention for a flat tube,
• Fig. 5a the partition wall area according to Fig. 5 in an enlarged view,
• Fig. 6 A fifth embodiment of the invention for a flat tube,
• Fig. 6a the partition wall area according to Fig. 6 in an enlarged view,
• Fig. 7 A sixth embodiment of the invention for a flat tube,
• Fig. 7a the partition wall area according to Fig. 7 in an enlarged view,
• Fig. 8 a seventh embodiment of the invention for a flat tube,
• Fig. 8a the partition wall area according to Fig. 8 in an enlarged view and
• Fig. 9 a tube fin block in a plan view with the flat tube according to the invention.

Fig. 1 shows a flat tube 1, which is made by forming a metal strip 2 and two chambers or flow channels 3, 4, which are separated by a multi-layer partition 5 from each other. The flat tube 1 has a first, lower flat side (also called a flat side) 1a and a second, upper flat side 1b, which are connected to each other at the end by rounded narrow sides 1c, 1d. The flat tube 1 has a depth t and a width b. The flat tube 1 is preferably used in a heat exchanger use and is the front side, flows from the narrow side 1c or 1d of air and flows through a liquid coolant. The partition wall 5 must therefore separate the flow channels 3, 4 tightly from each other, in particular, when the flow direction in the flow channels 3, 4 extends in opposite directions. The sheet-metal strip 2 is made of an aluminum material and preferably provided on one side with a Lotplattierung. After the forming process, the flat tube 1 is soldered so that it is sealed to the outside and inside (between the adjacent flow channels 3, 4).

Fig. 1a shows an enlarged view of the region of the partition wall 5, which is formed by six layers of the sheet-metal strip 2. The thickness of the sheet metal strip is denoted by d. From the lower flat side 1 a two folds 6, 7 are formed, which leave a gap 8 of the width e between them. Within the gap 8, two webs 9, 10 are added, which are angled perpendicularly from the edge strips of the sheet metal strip. The sheet-metal strip 2 has on one side a Lotplattierung, not shown, which forms the outside of the flat tube 1. Thus, solder surfaces 11, 12, 13 result between the folds 6, 7 and between the webs 9, 10. Thus, a tightness of the flat tube 1 is ensured to the outside. For a tightness between the adjacent flow channels 3, 4, the end edges of the webs 9, 10 are soldered to the bottom of the gap 8, which can be done by capillary action of the solder present on the outside. However, it is also possible to provide both sides of the sheet metal strip 2 with a Lotplattierung - then all contact surfaces of the six-layer partition 5 are soldered together. The two folds 6, 7 each have a height f, which together with the sheet metal strip thickness d gives the dimension b for the tube width. The webs 9, 10 have a web height s, which is smaller than the seam height f even at the most unfavorable tolerance deviation. This results after the joining of the tube between the end edges of the webs 9, 10 and the bottom of the gap 8, a gap a, ie the webs 9, 10 do not abut with their end edges on the bottom of the gap 8. This ensures that the pipe width b only depends on the seam height f and the sheet metal strip thickness d.

Fig. 2 shows a second embodiment of the invention for a flat tube 20 with a modified partition 21, which in Fig. 2a is enlarged. The partition wall 21 is formed six layers, ie six layers of the sheet metal strip are adjacent to each other and are soldered together. In contrast to the previous embodiment, the webs 22, 23 are formed in two layers, ie they each have an envelope 22a, 23a. From the lower flat side 21 a two folds 24, 25 are formed, which leave a gap 26 between them, which receives the double-layered webs 22, 23. The additional two layers results in an increased intrinsic stability the tube already in unsoldered condition. A solder plating, not shown, is provided on the outside of the flat tube 20, resulting in a soldering of the webs 22, 23 both together and on the contact surfaces with the two folds 24, 25 results. This sealing is achieved inwards and outwards. If necessary, in this embodiment, therefore, a corrosion-inhibiting layer or a Schutzplattierung (which is not soldering) are applied.

Fig. 3 shows a third embodiment of the invention for a flat tube 30 with a modified partition wall 31, which increases in Fig. 3a is shown. The partition is formed seven layers and has two folds 32, 33, a single-layer web 34 and a two-layer web 35 within the folds 32, 33. The partition wall 31 is thus formed asymmetrically. A Lotplattierung on the outside of the flat tube 30 is sufficient for a sufficient seal to the outside and inside, so that here also a Schutzplattierung on the inside can be made if necessary.

Fig. 4 shows two process steps of the forming process for the above-mentioned flat tube, in particular the embodiment according to Fig. 2 , The output stage of the method is an endless flat sheet metal strip 40 which has outer edge strips 40a, 40b and a width c. The sheet-metal strip 40 is a semi-finished product, which is unwound from a coil (not shown) and fed to a pipe forming machine, not shown. The width c is subject to certain manufacturing tolerances, ie the nominal size may vary up or down. These deviations must be compensated during the forming of the sheet metal strip. This happens as described above. The flat sheet metal strip 40 is formed in various stages in the tube forming machine to a finished flat tube, wherein in Fig. 4 (bottom) an essential stage in the form of an already partially formed sheet metal strip 40 'is shown. In its central region, two spaced, forming a distance folds 41, 42 are formed, which have a defined (calibrated) height f. The sheet-metal strip 40 'is bent over a length t', which corresponds approximately to the depth t of the finished tube, and the edge strips 40a, 40b are bent to double-layered webs 43, 44 and turned over.

In other process steps, not shown, the established band sections are bent with the webs 43, 44 corresponding to the two arrows P1, P2 inward until the double-layered webs 43, 44 engage between the two folds 41, 42 and thus according to the Fig. 2a are accurately positioned. The width of the finished tube then corresponds - as stated above - the sum of seam height f and tape thickness d. Preferably, the sheet metal strip 40 on the outside of the tube forming side on a Lotplattierung. After this forming process, the flat tube due to the inventive design of the partition and the forming process has a high intrinsic stability, especially against bending and torsion. Subsequent to the forming process, the endless manufactured flat tube is cut to length and completed with ribs, not shown, to a flat-tube heat exchanger, also not shown. Thereafter, the soldering process for the entire heat exchanger. From this it is clear that the flat tube after the forming process and before the soldering process is subjected to various other production stages in which it must retain its shape, which is ensured by the increased intrinsic and dimensional stability.

Fig. 5 shows a fourth embodiment of the invention for a flat tube 50 with a modified partition 51, which in Fig. 5a is shown enlarged. The partition 51 represents a development of the embodiment according to Fig. 3a it has two spaced-apart folds 52, 53 and a double-layered web 54 and a single-layer web 55, which has a fold 55a in the direction of the double-layered web 54 at its end. The double-layer web 54 rests on the folded portion 55a, which in turn rests on the inside of the flat tube. Again, preferably a Lotplattierung on the outside and, if necessary, a Schutzplattierung provided on the inside.

Fig. 6 shows a fifth embodiment of the invention for a flat tube 60 with a partition 61, which increases in Fig. 6a is shown. The partition 61 is five-ply and comprises a fold 62, a double-ply Bridge 63 and a single-layer, inwardly beveled web 64. Again, a Lotplattierung on the outside enough for a tightness to the outside and inward, ie a Schutzplattierung on the inside is possible. In contrast to the previous embodiments, therefore, only one fold 62 is provided, on which the two webs 63, 64 create from one side.

Fig. 7 shows a sixth embodiment of the invention for a flat tube 70 with a partition 71, which increases in Fig. 7a is shown. The partition wall 71 constitutes a modification of the embodiment Fig. 6a It is also five-ply and is formed by a fold 72, a two-ply web 73 and a single-layer web 74 with a fold 74a, which rests on the inside of the flat tube 70. The fold 74a is remote from the partition 71.

Fig. 8 shows a seventh embodiment of the invention for a flat tube 80 with a simplified partition 81, which increases in Fig. 8a is shown. The flat tube 80 has a lower flat side 80a and an upper continuous flat side 80b. The partition wall 81 is formed in three layers and comprises a fold 82 and a single-layer web 83, which is arranged between the two layers 82a, 82b of the fold 82. In order to achieve a seal inwards and outwards, here is a mutual Lotplattierung attached. The height of the fold 82 is again indicated by f, the height of the ridge 83 by s and the width of the tube by b. Between the end edge of the web 83 and the inner arc of the fold, in turn, a gap a is left, so that the tube width is uniquely determined by the pre-stamped fold 82.

Fig. 9 shows an application example of the flat tube according to the invention, here the flat tube 1 according to the embodiment according to Fig. 1, 1a , The flat tubes 1 are joined with corrugated fins 90 to a single-row heat exchanger block 91. The flat tubes 1 have due to the partition wall 5 on two flow channels 3, 4, which are flowed through in the same or opposite directions by a heat transfer medium, here preferably by a coolant. The ribs 90 are overflowed by air. The heat exchanger can preferably be used as a coolant radiator or radiator for a motor vehicle. The ends of the flat tubes 1 are connected by soldering to tube sheets, not shown. It is advantageous that the flat tubes have as smooth outer sides, so that there is a dense soldering. Preferably, the entire heat exchanger, z. B. a so-called Ganzaluminiumwärmeübertrager soldered in one operation in a soldering furnace, not shown.

According to a preferred embodiment, the flat tube according to the invention described above has the following dimensions: The width b of the flat tube, optionally including the Lotplattierung, is in a range of 0.5 to 10 mm, preferably in the range of 0.8 to 4 mm. The thickness d of the sheet metal strip is in a range of 0.08 to 2 mm, preferably in a range of 0.1 to 0.6 mm. The depth t of the flat tube is in a range of 6 to 100 mm, preferably in a range of 10 to 50 mm.

In the above embodiments, only one partition wall was shown, ie. H. the flat tube is designed as a two-chamber tube. However, other partition walls are possible, the z. B. can be produced by further folds, as disclosed in the aforementioned prior art.

Claims (13)

Flat tube for a heat exchanger, producible by forming and soldering a sheet metal strip (2, 40) with a thickness (d) and outer edge strips (40a, 40b), wherein the flat tube (1) has a first and a second flat side (1a, 1b) ), a pipe width (b) and a multi-layered partition (5) which forms adjacent flow channels (3, 4), wherein at least two layers of the partition wall as a fold with a seam height (f) and at least one layer as from one of the two Edge strips (40a, 40b) angled web with the web height (s) are formed, characterized in that the measure of the rebate height (h) and the sheet thickness (d) determine the dimension of the tube width (b) and that dimensional and dimensional deformations caused by the Stegmaßes (s) are absorbed by the rebate height (h). Flat tube according to claim 1, characterized in that the at least one fold (6, 7; 24, 25; 32, 33; 52, 53; 62, 72) is formed from the first flat side (1a). Flat tube according to claim 2, characterized in that two folds (6, 7; 24, 25; 32, 33; 41, 42; 52, 53) are arranged side by side and form a U-shaped gap (8, 26) between them. Flat tube according to Claim 1, 2 or 3, characterized in that the webs (9, 10; 22, 23; 34, 35; 43, 44; 54, 55; 63, 64; 73, 74) extend from the second flat side (9, 10; 1 b) are angled. Flat tube according to claim 1, 2, 3 or 4, characterized in that at least one web (22, 23; 34, 43, 44; 54, 63; 73) is double-layered and has an envelope (22a, 23a). Flat tube according to one of the preceding claims, characterized in that a web (55, 64, 74) has a bent end (55a, 64a, 74a). Flat tube according to claim 3, 4 or 5, characterized in that two webs (9, 10, 22, 23, 34, 35, 43, 44, 54, 55) are received in the U-shaped gap (8, 26). Flat tube according to claim 1, characterized in that the partition wall (81) is formed in three layers and has a fold (82, 82a, 82b) and a web (83), wherein the fold (82) and the web (83) by forming the Edge strips (40a, 40b) are formed. Flat tube according to claim 8, characterized in that the web (83) from the fold (82, 82a, 82b) is included. Flat tube according to one of claims 1 to 9, characterized in that the sheet-metal strip (1, 40) preferably made of an aluminum alloy, a Lotbeschichtung, preferably a Lotplattierung. Flat tube according to claim 10, characterized in that the solder coating on the outside (1a, 1 b) of the flax (1) forming side of the sheet-metal strip (2) is arranged. Flat tube according to claim 10, characterized in that the sheet-metal strip (40) has a solder coating on both sides. Flat tube according to claim 11, characterized in that on the inside of the flat tube, a corrosion-inhibiting coating, in particular a protective cladding is provided.

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