EP1281923B1 - Flat tube for heat exchanger and process of fabricating the same - Google Patents

Abstract

An economically formed tube of rectangular or oval-like cross section and with a corrugated internal fin includes spaced, relatively long side wall sections joined at their ends by relatively short end wall sections. An integral fin within the tube has crests and valleys defining a plurality of flow paths within the tube and is formed of a corrugated section of a strip employed to form one of the side walls and at least part of both of the end walls.

Description

The invention relates to a flat tube for heat exchangers, which is hergstellt from a sheet metal strip, in particular from a solder coated aluminum sheet strip wherein the flat tube has a plurality of corrugations formed from the sheet, which form a corresponding plurality of flow channels in the finished flat tube in the longitudinal direction of the flat tube. In addition, the invention relates to heat exchangers having such flat tubes and manufacturing method for the flat tubes.

A flat tube of the type described is known from EP 646 231 B1, wherein the known flat tube is not provided specifically for "tube bottomless" heat exchanger. Rather, the flat tubes from EP 646 231 are not suitable, in the sense of the not yet published patent application DE 100 16 113.8 to be bent at the ends to form a Einströmtrichter.

From US 4,805,693 a further flat tube is known, which must be composed of three parts, which is to be regarded as rather expensive. In addition, the ends of this flat tube also can not be bent to form a Einströmtrichter, because that is the one flat side of the flat tube forming part, the part enclosing the other flat side or includes.

The flat tube known from EP 907 062 consists of two parts, but has no corrugations which form a multiplicity of flow channels in the interior of the flat tube. If such a tube for intercooler be used, there must be used an inner plate, resulting in an undesirable overhead. Similar disadvantages must the flat tube from the British Patent Publication No. 683 161, from 26.11. 1952, to be assigned. All in all, this field of technology was and still is characterized by many publications, probably because the pipes used are among the most important components of the heat exchangers.

The object of the invention is to further form a flat tube in the way that it is relatively inexpensive to produce and can be bent on the one hand at the ends, with the narrow sides of the bent flat tube ends favorably with the edges of collection or deflection of a tube bottomless Can connect heat exchanger, which should be equipped with such flat tubes and on the other hand but also for heat exchangers with tube plates should be advantageous.

The tubular bottomless heat exchanger is evident from claim 10 and the heat exchanger with tube plates has the features of claim 11. The manufacturing method is in a first variant subject of claim 12th A second variant is apparent from claim 13.

Because the flat tube consists of two parts, which are connected to each other at the narrow sides, each part forms one broad side of the flat tube and the corrugations are integrally formed on one part, so that the wave crests lie on the other part inside and because the joints of the two parts are arranged in the narrow sides within the cross section of the flat tube, the flat tube is particularly - but not exclusively - for heat exchangers without tube bottoms. At such flat tubes after joining (or previously) of the cooling network, consisting of each formed flat tubes with interposed corrugated fins, at the ends of the flat tubes forming a funnel inlet bend are attached to the part of the flat tube, which is not provided with the corrugations is. This part is essentially flat and therefore particularly suitable for being bent at the ends. The relatively large width of the narrow sides makes such flat tubes valuable especially for intercoolers. Also, because the inner plate, which is advantageous for intercooler tubes, was integrated with the flat tube according to the invention with the same. Furthermore, the relatively wide narrow sides and provided according to claim 2 approximately rectangular cross-section of the flat tubes provide very favorable seam preparations for the subsequently performed solder joint of the flat tube ends with the edges of the manifolds.

A further advantage is that at least one of the two parts which form a flat tube, have means which allow a pre-positioning of the flat tube halves to each other before soldering.

It should, however, be emphasized that the flat tubes according to the invention can also be used to advantage in heat exchangers which are not "tube-less", ie which have conventional and well-known tubesheets, in whose openings the ends of the flat tubes are soldered in. In such heat exchangers, the collection boxes are connected to the edge of the tubesheets.

The flat tube having the features of claim 4 has outwardly curved - ie convex - narrow sides and the joints of the flat tube halves are located in the middle between the broad sides or in the middle of the narrow sides. Such flat tubes can be more easily inserted into the corresponding openings of the tube sheets and soldered therein, because the soldering problems often present in the corner areas have been eliminated. Furthermore, flat tubes with convex narrow sides have better flow properties, since they are flown by the cooling air and cause less pressure loss there.

The manufacturing method according to the invention provides in a first variant that the flat tube is assembled from two parts, wherein previously on one part of a band edge, the corrugations are formed and the other edge of the band is folded over to form the narrow side of the later flat tube, then the corrugations are applied to the later inside of a broad side of the flat tube, wherein a second fold is generated in the sheet metal strip, which forms the other narrow side of the later flat tube, then both folds are erected and formed the joints, then the other part of the band edges reshaped so that there are created with the joints corresponding surfaces and means that hold the two parts in position before soldering.

A second advantageous variant provides that the flat tube is assembled from two parts, whereby previously parts of the corrugation are formed on the two band edges of one part, that thereafter both parts of the corrugation are applied to the later inner side of one broad side, wherein two folds be produced in the metal strip, that the folds formed to the later narrow sides of the flat tube and the joints are formed, then the other broadside having another part of the flat tube at the band edges is formed so that there are provided with the joints corresponding surfaces and means, holding the two parts in position before soldering.

The aforementioned method leads to a flat tube whose band edges are arranged relatively far to a narrow side. The second method results in a flat tube in which the band edges lie within the corrugation.

In the following, the invention will be described in exemplary embodiments, reference being made to the accompanying drawings. From this description, other possibly significant features and effects arise.

• Fig. 1 eine Variante des Flachrohres;
• Fig. 2 zweite Variante des Flachrohres;
• Fig. 3 dritte Variante des Flachrohres;
• Fig. 4 Perspektivische Ansicht auf einen rohrbodenlosen Wärmetauscher;
• Fig. 5 Perspektivische Ansicht auf das Flachrohr;
• Fig. 6 Seitenansicht auf den Wärmetauscher;
• Fig. 7 Schnitt A - A aus Fig. 6;
• Fig. 8 Schnitt B - B aus Fig. 6;
• Fig. 9 Einzelheit "X" aus Fig. 7;
• Fig.10 eine vierte Variante des Flachrohres;
• Fig.11 die Herstellungsfolge eines Flachrohrteiles;
• Fig.12 Einzelheit "Y" aus Fig. 11;
• Fig.13 Einzelheit "Z" aus Fig. 11;
• Fig.14 eine andere Herstellungsfolge;

The figures show folgerides:

• Fig. 1 shows a variant of the flat tube;
• Fig. 2 second variant of the flat tube;
• Fig. 3 third variant of the flat tube;
• Fig. 4 Perspective view of a tube bottomless heat exchanger;
• Fig. 5 Perspective view of the flat tube;
• Fig. 6 side view of the heat exchanger;
• Fig. 7 section A - A of Fig. 6;
• Fig. 8 section B - B of Fig. 6;
• Fig. 9 detail "X" of Fig. 7;
• 10 shows a fourth variant of the flat tube;
• 11 shows the production sequence of a flat tube part;
• Fig.12 Detail "Y" of Fig. 11;
• Fig.13 detail "Z" of Fig. 11;
• Fig. 14 shows another production sequence;

The flat tube 1 shown in detail in FIGS. 1 to 3 and in FIG. 10 is made of solder-coated sheet metal strip of small thickness (about 0.15-0.20 mm) made of aluminum. 1 and 2 show only a portion of the cross section 10 of the flat tube 1, while the variant in Fig. 3 shows the entire flat tube cross-section. The cross section 10 is limited by the broad sides 3 and the narrow sides 2 . The flat tube 1 consists in all variants of the parts 1a and 1b. Both parts 1a and 1b are produced separately on systems equipped with sets of rollers, wherein the roller sets are designed such that the forming operations take place gradually and at the end the two parts 1a and 1b are present. This has not been shown in detail with respect to the flat tubes in FIGS. 1 to 3, but in FIG. 3 the two band edges have been designated 50 in the part 1a . In the embodiments shown, they are located exactly in the middle of the broad side 3 , but they could also be arranged off-center, as shown in FIGS. 11 to 13, which are described below. Thus, it can be seen from FIG. 3 and from FIG. 14 that first the corrugations 4 are formed on both band edges 50 and then, step by step, the folding takes place, then that the different end shapes of the parts 1a and 1b shown in Figs. 1 to 3 arise. In each case a part 1a plus a part 1b , the finished flat tube 1, which is shown in Figs. 1 to 3 on the left edge of the picture. The corrugations 4 on the part 1a result in the finished flat tube, the flow channels 5. The wave peaks 14 of the part 1a are inside the broad side 3 of the part 1b fitting to be soldered after assembly. In FIGS. 1 and 2, in principle identical parts 1a were used, which differ only in their dimensions. The parts 1b differ in that in FIG. 1 the band edges 50 have a simple fold 25 , whereas in FIG. 2 the band edges 50 have been U-shaped. At the U - shaped band edges 50 , two legs 21 are present, which are connected by a connection 22 . The connections 22 are double-walled in FIGS. 1 and 2 on both parts 1a and 1b and form the narrow side 2. This has created a very good stability of the flat tube 1 in this area, which, for example, when the heat exchanger is used in the motor vehicle against Rockfall or against other mechanical effects is very appropriate. For example, in the part 1a with the double-walled narrow sides 2 (FIGS. 1 and 2), first in a first step, the corrugation 4 is rolled into the band edges 50 . Thereafter, the corrugations 4 are placed vertically by two folds are mounted in the sheet metal strip, the already formed in the finished part 1a inwardly (in the flat tube 1 in) end of the joint 20 . Subsequently, the folding takes place, wherein the double-walled narrow side 2 is prepared. The corrugations 4 are already on the broad side 3 . Thereafter, the left and right double-walled band edges (the expectant narrow sides 2 or connections 22 ) are folded and that first the fold on the joints 20 and finally the fold to the broadside 3. In the part 1a with a simple wall in the narrow sides 2 (Fig. 3), the corrugations 4 are also rolled first and then the corrugations 4 are placed vertically by two bends are mounted in the sheet metal strip. These bends already represent the edges to the broad side 3. Thereafter, the edge 20 belonging to the joint 20 is created in the narrow side 2 , whereupon the corrugations 4 are again placed vertically to finally create the second, inner edge of the joint 20 and the corrugations 4 to create the broadside 3 . On the plants mentioned above, the described manufacturing steps merge.

A description of the manufacturing sequence for the parts 1b seems to be dispensable because of its simplicity.
In all of FIGS. 1 to 3, as the means 40 which holds the parts 1a and 1b in position before soldering, a bent edge 41 is provided on the part 1b . This edge 41 engages over the one leg 21 of the "U" on the part 1a, and thus can perform its intended purpose, as shown in FIGS. 1 to 3 to see. It depends mainly on the proper positioning transversely to the longitudinal axis of the flat tube 1 , which is ensured by the edge 41 . It will be understood that a like-acting rim 41 or an equivalent embodiment could also be (or alone) on the part 1a , as it was provided in an embodiment not shown. In the embodiment of FIG. 3, no double wall thickness was provided in the narrow sides 2 . The question of which design of the flat tube 1 one decides will be decided inter alia by the conditions of use of the heat exchanger.
In the left-hand illustration of FIG. 3, the middle of the narrow sides 2 has been marked and designated 30 . It is advantageous, but not necessary, for the joints 20 formed by the edges of the parts 1a and 1b to be located outside this center 30 . In particular, the joints 20 should be closer to the substantially smooth part 1b . This is advantageous in the use of such flat tubes 1 described below in tube-bottomless heat exchangers. It is also essential that the joints 20 are within the area encompassed by the narrow sides 2 and the broad sides 3 cross-section 10 of the flat tube 1 . As a result, there are substantially smooth narrow sides 2 , which later, after joining the existing of flat tubes 1 and corrugated fins 12 cooling network, allow an ideal solder joint of the ends of the narrow sides 2 with the Verbindungsrändem 15 of the manifolds 14 .

4 to 9 of the described flat tubes 1 having tubular bottomless heat exchanger was shown, which will be explained below. In further details, such a heat exchanger has been described in the not yet published above-mentioned application DE 100 16 113.8, which should be considered as published at this point in case of need. As can best be seen from the perspective view in FIG. 4, the heat exchanger consists of the cooling network, the two header boxes 14 and preferably also of side panels 60.

In the section from the heat exchanger according to FIG. 4 , only one side part 60 and a collecting box 14 can be seen. At the lower end of the cooling network, not shown, is the second collection box and the left side of the cooling network, not shown, the other side part is arranged. It is also perfectly clear that there must be an inlet and outlet at the collecting boxes 14 at a functioning heat exchanger, so that a heat-exchanging means, in this case the cooling liquid of an internal combustion engine not shown, can flow through the heat exchanger. The other heat exchanging means is the cooling air flowing through the corrugated fins 12 . If the parts 1a and 1b of the flat tube 1 shown again in FIG. 5 have been produced, the joining together of the cooling network consisting of the corrugated fins 12 and the flat tubes 1 can take place. In this case, a part 1a and a part 1b each form a flat tube 1 . After assembly of the cooling network takes place in a suitable device, not shown, the attachment of the bend 80 at the ends of the parts 1b. It should be noted that this deflection 80 can be mounted even before the assembling of the cooling network, or the two parts 1a and 1b to the flat tube 1 at the ends of the parts 1b. The bend 80 is made in each case so that the broad side 3 of the bent portion 1b on the broad side 3 of the adjacent flat tube 1, and indeed, always on the broad side 3 of the part 1a of the adjacent flat tube 1 so rests that there is an excellent solder joint between the broadsides 3 is possible. Subsequently, the side parts 60 are added and the collecting boxes 14 are pushed with their Verbindungsrändem 15 on the narrow sides 2 of the flat tubes 1 arranged in series. Subsequently, the heat exchanger is manufactured in a single soldering operation, because all parts are made of aluminum sheet, which is suitably solder coated. Fig. 6 shows a partial side view of the heat exchanger described above. FIG. 7 shows a section through the same, which was placed exactly at the lower end of the connecting edges 15 , or just below the turns 80. The corrugated ribs 12 arranged between the broad sides 3 of adjacent flat tubes 1 were not drawn here. From Fig. 9 it can be seen that flat tubes 1 were used for the heat exchanger, which have been shown in Fig. 3 and already described in front. Even if these flat tubes 1 no double wall thickness own in their narrow sides 2 , they have there, by the arrangement of the joints 20 in the narrow sides 2 , a sufficient stability.

Fig. 10 shows a flat tube 1 which is better suited for heat exchangers having tubesheets. The narrow sides 2 of this flat tube 1 are rounded, so that the inflowing cooling air flow can flow through the heat exchanger advantageously with less pressure loss. This flat tube 1 also has a double wall in the region of the narrow sides 2 . The shocks 20 are located exactly on the middle 30 between the two broad sides. 3

From FIGS. 11-13, one of the two manufacturing processes emerges, namely the deformation of the part 1a. The production of the relatively simply deformed part 1b results, for example, from FIG. 2. The production of the part 1a will now be described. 11 shows from top to bottom a total of 7 representations which illustrate the individual steps. The steps can be partly parallel but also consecutive. It begins with the formation of the corrugation 4 on the right edge of the band 50 . At the left edge of the band 50 , a fold 70 is attached. (Fig. 12) Thereafter, according to the (from the top) 3rd and 4th illustration, the corrugation 4 is applied to the inside of one broad side 3 . In this case, the bend in the sheet metal strip takes place in such a way that the fold 71 according to FIG. 13 is produced. The narrow sides 2 are formed by setting up the folds 70 and 71 . At these folds 70, 71 , the webs 20 are formed, at which the two parts 1a and 1b are later connected by means of soldering. In this manufacturing method, the band edges 50 on the finished part 1a are relatively close to one of the narrow sides 2, as can be seen from FIG. 11.

FIG. 14 (4 individual hand sketches) shows the alternative production in which the two band edges 50 are present within the corrugation 4 at the end. In Fig. 14, the band edges 50 abut each other approximately in the middle of the broad side 3 . First, the parts of the corrugation 4 are formed on both band edges 50 . Thereafter, according to the arrows, both parts of the corrugation 4 are folded inwards. The folds 70, 71 are created . The double-walled narrow sides 2 are already prepared, as can be seen from the illustration. Subsequently, in the left and right double-walled sections only two folds must be attached, leading to the narrow sides 2 and the abutment surfaces 20 . It can be seen that this is not the whole Narrow side 2, but only a substantial part thereof, which is represented by the connection 22 of the two legs 21 of the "U".

Claims (14)

1. Flat tube for heat exchangers, which is produced from a sheet-metal strip, in particular from a solder-coated sheet-aluminium strip, the flat tube (1) which has two narrow sides (2) and two wide sides (3) possessing a multiplicity of corrugations (4) which are shaped from the sheet metal and form, in the finished flat tube (1), a corresponding multiplicity of flow ducts (5) in the longitudinal direction of the flat tube (1), characterized in that the flat tube (1) consists of two parts (1a and 1b) which are connected to one another on the narrow sides (2), each part (1a and 1b) in each case forming a wide side (3) of the flat tube (1), and the corrugations (4) being integrally formed on one part (1a), so that their wave crests (14) bear on the inside against the wide side (3) of the other part (1b), and in that the joints (20) of the two parts (1a, 1b) are arranged in the narrow sides (2) and within the cross section (10) of the flat tube (1) and have means (40) which hold the two parts (1a, 1b) in position before soldering.
2. Flat tube according to Claim 1, characterized in that the joints (20) are arranged outside the middle (30) of the narrow sides (2) and the cross section of the flat tubes (1) is approximately rectangular.
3. Flat tube according to Claims 1 and 2, characterized in that the joints (20) run nearer to that wide side (3) of the flat tube (1) which is formed by the part (1b) on which no corrugations (4) are located.
4. Flat tube according to Claim 1, characterized in that the joints (20) are arranged in the middle (30) between the wide sides (3), and the narrow sides (2) have a convex (outwardly curved) configuration.
5. Flat tube according to one of the preceding claims, characterized in that the narrow sides (2) of the flat tube (1) possess a double wall thickness.
6. Flat tube according to one of Claims 1 to 4, characterized in that the narrow sides (2) possess a single wall thickness.
7. Flat tube according to one of the preceding claims, characterized in that the joints (20) are formed by edges, formed in a U-shaped manner, of the parts (1a and 1b), the said edges bearing with a leg (21) of the "U" one against the other, so that the connection (22) of the legs (21) forms the respective narrow side (2).
8. Flat tube according to one of Claims 1 to 6, characterized in that the joints (20) are formed by edges, formed in a U-shaped manner, on one part (1a) and from folded edges (25) on the other part (1b).
9. Flat tube according to Claim 7 or 8, characterized in that the means (40) for positioning the two parts (1a, 1b) consist in the leg of the "U" on one of the parts (1b) being longer than the other leg of the "U" on the other part (1a) or in that the fold (25) at the edges of the part (1b) is longer than the leg (21) of the "U" on the other part (1a) and the inwardly projecting edge (41) present as a result is bent round, in order to achieve a prefixing of the two parts (1a and 1b).
10. Heat exchanger without a tube bottom, consisting of flat tubes (1) formed from two parts (1a and 1b) and of corrugated ribs (12) arranged between them, the flat tubes (1) connecting two opposite headers (14) in such a way that at least one of the parts (1a, 1b) of the flat tubes (1) is bent round at the ends, in order to bear with its wide side (3) against the wide side (3) of the adjacent flat tube (1), the ends being bordered on the narrow sides (2) of the flat tubes (1) by the connecting edges (15) of the headers (14), the flat tubes (1) being designed according to at least one of Claims 1-3 and/or 5-9, characterized in that the bent-round part of the flat tube (1) is the part (1b) on which no corrugations (4) are integrally formed.
11. Heat exchanger with tube bottoms which have orifices in which the opposite ends of the flat tubes (1) are soldered, the edge of the tube bottoms being surrounded by the connecting edges of the headers, characterized in that the flat tubes (1) are designed according to Claim 1 or Claims 1 and 4.
12. Method for the production of a flat tube for heat exchangers which has the features of Claim 1 and is produced on plants equipped with roller sets, characterized in that the flat tube (1) is assembled from two parts (1a, 1b), the corrugation (4) previously being integrally formed on one part (1a) at one strip edge (50), and the other strip edge (50) being folded round (70) in order to form one narrow side (2) of the subsequent flat tube (1), the corrugation (4) is laid onto the subsequent inside of one wide side (3) of the flat tube (1), a second fold (71) in the sheet-metal strip being produced, which forms the other narrow side (2) of the subsequent flat tube (1), thereafter the two folds (70, 71) are straightened up and the joints (20) are integrally formed, and then the other part (1b) having the other wide side (3) of the flat tube (1) is formed at the strip edges (50) in such a way as to produce there faces and means (40) which match with the joints (20) and hold the two parts (1a, 1b) in position before soldering.
13. Method for the production of a flat tube for heat exchangers which has the features of Claim 1 and is produced on plants equipped with roller sets, characterized in that the flat tube (1) is assembled from two parts (1a, 1b), parts of the corrugation (4) being integrally formed previously at the two strip edges (50) of one part (1a), in that, thereafter, the two parts of the corrugation (4) are laid onto the subsequent inside of one wide side (3), two folds (70, 71) being produced in the sheet-metal strip, in that the folds (70, 71) are formed into the subsequent narrow sides (2) of the flat tube (1) and the joints (20) are integrally formed, and then the other part (1b), having the other wide side (3), of the flat tube (1) is formed at the strip edges (50) in such a way as to produce there faces and means (40) which match with the joints (20) and hold the two parts (1a, 1b) in position before soldering.
14. Method according to Claim 13, characterized in that each of the parts of the corrugation (4) amounts to approximately half of the entire corrugation (4), so that the strip edges (50) are assembled approximately in the middle of the wide side (3).

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