EP0379701B1 - Heat exchanger - Google Patents

Description

The invention relates to a heat exchanger, in particular a refrigerant condenser, of the type specified in the preamble of claim 1. Such a heat exchanger is known from EP-A-0 255 313. In this condenser, which is part of the prior art, the ends of extruded flat tubes are guided into elongated slots in a tubular connection box and are soldered to the connection box. In such a production, the ends of the flat tubes must correspond exactly to the dimensions of the slots so that the tightness of the solder joint is achieved. The corrugated fins are provided with a solder layer in order to be soldered to the flat tubes which have no solder. In the known arrangement, it is necessary to have different connection boxes for different pipe cross sections manufacture, universal use of a uniform type of junction boxes for different pipe cross sections is therefore not possible.

US Pat. No. 3,689,972 describes a method by which, in a flat tube heat exchanger, after the tubes have been soldered into the terminal boxes, the terminal boxes are deformed to a desired cross-sectional shape. Since the soldering of flat tubes into corresponding slots in connection boxes is particularly problematic in the area of the parallel flat sides, it was proposed in EP-A-0 198 581 to provide the bottom of the connection boxes with bulges, which results in better soldering of the flat tubes the connection boxes should result.

Furthermore, it is known from US-A-3,857,151 to reshape the tube ends to a round cross section in a flat tube heat exchanger in order to fasten the tube without soldering in a tube sheet. For such a pipe / floor connection, however, it is necessary that there be a correspondingly long connecting surface between the pipe and floor in order to ensure the required strength and tightness. However, it has been found that solderless connections are not refrigerant-tight, so that solderless heat exchangers can only be used to a limited extent and are unsuitable for refrigeration circuits.

A heat exchanger suitable for refrigeration circuits is described in DE-A-36 22 953. This heat exchanger consists of flat tubes, the tube ends of which are widened compared to the central sections, the parallel sides of the ends of adjacent tubes lying against one another. This heat exchanger has none Junction boxes, because the adjacent pipe ends of the parallel flat tubes are connected to each other and thus take over the function of the junction boxes.

From FR-A-2 390 696 a heat exchanger is known which consists of a plurality of tubes with an elongated oval cross section, the ends of which protrude into end plates. The ends are formed into a circular cross-section and are located in corresponding flanges in the end plates, with the pipe ends and the flanges lying on one end in one plane. The ends of the pipes are welded to the flanges using a special welding device. For the manufacture of such a heat exchanger, a special welding device is required, with which the individual welded connections have to be made in succession.

It is therefore the object of the present invention to provide a heat exchanger of the type specified in the preamble of claim 1, in which a mechanically solid and fluid-tight, in particular refrigerant-tight connection of the tube and the bottom and a high strength of the flat tube is achieved and in which the corrugated fins can be soldered to the flat tubes without additional soldering.

This object is achieved in a heat exchanger of the type mentioned by the characterizing features of claim 1.

The main advantages of the invention are seen in particular in the fact that a high level of manufacturing reliability is achieved, since tolerances in the section with radial pressure are completely eliminated, and connection boxes with uniform connecting pieces or openings can be used due to the cross sections of the pipe ends, which are independent of the dimension of the flat pipe . Another advantage is that the flat tubes are extremely dimensionally stable and can also withstand extreme pressure loads both from the inside and from the outside, because the webs not only act as supports, but also as a tie rod between the parallel flat sides of the pipes.

The flat tubes are expediently designed as welded aluminum tubes, since on the one hand they meet the requirements with regard to their high strength and on the other hand with regard to the formability of the tube ends.

So that there is no lost installation space between the heat exchanger network and the connection boxes, it is advantageous that the round ends are integrally formed on the flat tubes without a transition area. However, a short transition area between the flat tube and the round tube ends can also be provided, in particular for reasons of flow or production technology. Both a tube with a flat cross-section, the ends of which have been formed into a circular or oval cross-section, can be assumed, but tubes with an originally round cross-section are also considered, which are compressed in the area between the ends to a flat tube cross-section with parallel side walls . In the case of circular tube ends, however, it is important that the support webs to be soldered are introduced into the tube before the deformation process of the tube or the tube ends, with oval expanded tube ends a subsequent insertion of the support webs is also possible.

To increase the strength in the area of the pipe / floor connection, it is proposed that the openings of the connection boxes be surrounded by connection pieces which are directed into the connection boxes or towards the corrugated fins. In this way there is a larger one Contact surface between pipe and floor, which leads in particular to an increase in mechanical strength.

An expedient embodiment of the subject matter of the invention is that the ends of the flat tubes are located in openings in the connection boxes and the section with radial pressure is produced by radially widening the ends in the region of the base. This expansion can be done using a mandrel. If the ends of the flat tubes are inserted over connection pieces at the bottom of the connection box, it is expedient that the radial pressure between the tube end and the base is generated by radially pressing the tube ends together.

In order to reduce the number or length of the soldered connections on the connection box, the connection box can be designed as a one-piece tube. In such an embodiment, the pipe forming the connection box can initially be open on its side diametrically opposite the pipe ends of the flat pipes, so that a tool for widening the pipe ends can be introduced into the ground. As soon as the press fit between the pipe ends and the bottom is created, the pipe forming the connection box is deformed in such a way that a closed pipe shape is formed, the seam of which is welded shut.

Another embodiment of the invention is that the connection boxes consist of two concentrically nested tubes, the outer tube having openings diametrically opposite the openings for receiving the tube ends of the flat tubes, which are covered by the inner tube. These opposite openings serve that a tool for Generation of radial pressure can be introduced. When the heat exchanger is soldered, the inner tube is soldered to the outer tube, so that the openings opposite the tube sheet are closed in a liquid-tight or refrigerant-tight manner.

A variant of the connection boxes is that they each comprise a base part and a cover part, which are soldered to one another at the connecting surfaces. With this configuration, a widening tool can first of all be introduced inexpensively into the pipe ends in order to generate the pressure, and then the cover part is placed on the base part. The cover part and the base part are soldered simultaneously with the soldering of the corrugated fins to the flat tubes and the tube ends in the base of the connection box. The cover parts and base parts preferably have overlapping and / or interlocking regions, as a result of which there is a large soldering area and thus a high mechanical strength.

To determine the direction of flow through the pipe system of the heat exchanger, for example in a zigzag shape, and to divide the flow with respect to different flow cross sections, it is expedient to arrange means for flow deflection in the connection boxes. These means for deflecting the flow can be formed, for example, by angled sections of the cover parts. With this design, the number of solder connections can be reduced to a minimum. If profile material is to be used for the cover parts, the means for deflecting the flow are between cover part sections inserted partitions formed.

Not only drawn, welded or soldered tubes come into consideration for the heat exchanger according to the invention, but the flat tubes can also consist of an extruded profile which has at least one support web between the parallel side walls over the entire, non-deformed length. Such extruded profiles offer a particularly high strength, but the effort required to produce a round tube end from an extruded flat tube is greater than with the other tube types.

Exemplary embodiments of the heat exchanger according to the invention are explained in more detail below with reference to the drawing.

• Fig. 1 einen Längschnitt durch einen Wärmetauscher,
• Fig. 2 einen Schnitt durch einen Anschlußkasten nach der Linie II-II in Fig. 1,
• Fig. 3 einen Schnitt durch einen Wärmetauscherblock nach der Linie III-III in Fig. 1,
• Fig. 4 einen Schnitt durch ein Wärmetauscherrohr mit den Anschlußkästen nach der Linie IV-IV in Fig 1,
• Fig. 5 einen Ausschnitt einer alternativen Ausführungsform zur Darstellung in Fig. 1,
• Fig. 6 einen Schnitt nach der Linie VI-VI in Fig. 5,
• Fig. 7 eine alternative Ausführungsform zu Fig. 6 in vergrößerter Darstellung,
• Fig. 8 einen Schnitt durch einen aus zwei konzentrischen Rohren bestehenden Anschlußkasten,
• Fig. 9 einen Schnitt durch einen längsnahtgeschweißten Anschlußkasten,
• Fig. 10 eine Ausführungsvariante zu Fig. 9,
• Fig. 11 - Fig. 16 verschiedene Ausführungen von Anschlußkästen, die aus Bodenteil und Deckelteil gebildet sind,
• Fig. 17 eine Ausführungsvariante zu Fig. 8,
• Fig. 18 eine vergrößerte Darstellung des Flachrohrendes im Boden.

The drawing shows:

• 1 shows a longitudinal section through a heat exchanger,
• 2 shows a section through a connection box along the line II-II in FIG. 1,
• 3 shows a section through a heat exchanger block along the line III-III in FIG. 1,
• 4 shows a section through a heat exchanger tube with the connection boxes along the line IV-IV in FIG. 1,
• 5 shows a section of an alternative embodiment for illustration in FIG. 1,
• 6 shows a section along the line VI-VI in FIG. 5,
• 7 shows an alternative embodiment to FIG. 6 in an enlarged view,
• 8 shows a section through a connection box consisting of two concentric tubes,
• 9 shows a section through a longitudinally welded connection box,
• 10 shows a variant of FIG. 9,
• 11 - FIG. 16 different versions of connection boxes which are formed from the base part and cover part,
• 17 shows a variant of FIG. 8,
• Fig. 18 is an enlarged view of the flat tube end in the bottom.

In Fig. 1 the section through a heat exchanger 1 is shown, which comprises a plurality of parallel flat tubes 2 and corrugated fins 3 arranged between them. The flat tubes 2 have ends 2 * with a round cross section, which are formed directly on the flat tubes 2 without a transition region and are fastened in corresponding openings 4 of connection boxes 5. The connection boxes 5 are formed from a bottom part 6 and a cover part 7. In Fig. 1, the upper connection box 5 comprises two cover parts 7 *, 7 **, which together cover the entire bottom part 6. In this case, inwardly angled sections 8 of the cover parts 7 * and 7 ** form flow guiding means by which the distribution of the total fluid flow over a certain number of pipes connected in parallel is determined.

In the flat tubes 2 there are support webs 14 which are soldered to the inner wall of the flat tubes 2 and in this way give the flat tubes great stability both under pressure from the inside and under pressure from the outside. The upper cover part 7 * shown on the left in FIG. 1 has a fluid inlet 10 and the cover part 7 ** shown on the right has a fluid return 11. The cover parts 7, 7 * and 7 ** are soldered to the respective base parts 6 along the circumferential edge, with a large soldering area overlapping areas 12 are provided.

The bottom parts 6 have connecting pieces 9 directed into the connection box, which surround the openings 4. The tube ends 2 * are fastened in the base parts 6 in a liquid-tight or refrigerant-tight manner by radial expansion and additional soldering. In order to limit the lateral face of the heat exchanger 1 and to support the respective outer corrugated fins 3, side parts 13 are soldered on.

Fig. 2 shows a section along the line II-II in Fig. 1. From this illustration it can be seen that the connecting piece 9 and also the ends 2 * of the flat tubes 2 have a circular cross section. The cover parts 7 * and 7 ** are located within a peripheral edge 6 * of the base part 6, on the narrow sides of which the side parts 13 are fastened.

In Fig. 3 is a section along the line III-III in Fig. 1 is shown. From this illustration, one can see the elongated cross section of the flat tubes 2 with the support webs 14 located therein. The corrugated fins 3 are arranged between each two adjacent flat tubes 2 or between the respective outer flat tubes 2 and the side parts 13. The corrugated fins 3 are soldered to the flat surfaces of the flat tubes 2 and the side parts 13.

FIG. 4 shows the section along the line IV-IV in FIG. 1. This view shows the flat tube 2 in its long axis of the cross section with the round ends 2 * formed thereon. Located in the flat tube 2 there is a metallic insert that forms the support webs 14. The ends 2 * of the flat tubes 2 are located in the connecting piece 9 of the base parts 6, which together with the cover part 7 or 7 * form the lower or upper connection box 5. The fluid inlet 10 is located on the upper connection box 5.

FIG. 5 shows a section of a longitudinal section through a heat exchanger 1, which has a different construction of the connection box 5 compared to the embodiment in FIG. 1. The heat exchanger block is formed from parallel flat tubes 2 and corrugated fins 3 located between them, the ends 2 * of the flat tubes 2 being located in openings 16 in a base part 15. In this embodiment, the base part 15 is of flat shape and has angled side walls 15 * only on the two narrow sides.

The ends 2 * of the flat tubes 2 are initially held in the base part 15 by radial pressing as a result of radial expansion and later these joints are additionally soldered when the heat exchanger 1 is soldered. This will be discussed in more detail later in the description of FIG. 18.

The bottom part 15 forms, together with an arcuate profile piece 17, the connection box 5, which has an inserted partition wall 18 as a means for deflecting the flow. In this way it is very easy to divide the tube groups of the heat exchanger, since the partitions 18 are provided at any points and accordingly the partial lengths of the profile pieces 17 can be determined. On the side of the heat Exchanger 1 is the side part 13 which engages with an angled end 13 * over the upper edge of the cover part 17.

Fig. 6 shows a section along the line VI-VI in Fig. 5. From this view it can be seen that the cover part 17 consists of an arcuate profile piece which is placed on the bottom part 15. The bottom part 5 is provided along its long sides with an upwardly directed edge 15 **, through which an overlapping region 12 of the bottom part 15 and the cover part 17 results.

Fig. 7 shows an enlarged version of an embodiment of Fig. 6. In this embodiment, the cover part 17 is V-shaped (in this case upside down) and the upward edges 15 ** along the long side of the bottom part 15 arranged at an angle to the longitudinal axis of the base part 15, which is adapted to the V-shape of the cover part 17. This design of base part 15 and cover part 17 results in a positive connection, which additionally creates an overlapping area 12 with a corresponding soldering surface.

8 shows a section through a connection box 5 with an end 2 ** of a flat tube 2 fastened therein. The connection box 5 consists of two concentric pipes, an outer pipe 19 having openings 20 for receiving the pipe ends 2 * and diametrically opposite further openings 21. The openings 21 are provided so that a tool for generating a radial pressure between the pipe end 2 * and the outer tube 19 is inserted. After this step, an inner tube 22 is arranged concentrically in the outer tube 19 so that the openings 21 are covered. When the heat exchanger is soldered, the ends 2 * of the flat tubes 2 and the inner tube 22 are soldered to the outer tube 19, which results in a fluid-tight connection.

Fig. 9 shows an embodiment of the connection box 5 with a one-piece tube 23. This tube 23 is initially open in the manufacture of the heat exchanger on its upper side, the gap in the lateral surface of the tube 23 being sufficient to provide a tool for generating the radial pressure between to insert the pipe end 2 * and a connecting piece 24 of the connection box 5. After the radial pressure has been produced, the jacket parts of the tube 23 are deformed in such a way that they form a closed shape and finally the seam 25 is welded shut.

In Fig. 10 an embodiment of the connection box 5 is shown, in which this consists of a one-piece tube 26 with outwardly directed connection piece 27. An end 2 ** with a round cross-section of a flat tube 2 is inserted over the connecting piece 27 and is pressed against the connecting piece 27 by the force acting radially inwards.

11 to 14 show different variants of junction boxes 5, which essentially correspond to FIG. 6 with regard to the two-part design. The variations relate to the cross-sectional shape of the connection boxes, each consisting of a base part 15 and a cover part 17 exist. The bottom parts have outwardly directed connecting pieces 28 which surround the openings 4 for receiving pipe ends. The designs according to FIGS. 12 and 13 have particularly large overlapping areas 12 between the base part 15 and the cover part 17. The design of the connection boxes 5 in FIGS. 11 to 14 enables the use of deep-drawn parts, which is favorable in view of the manufacturing costs.

15 shows a connection box 5, in which a bottom part 29 has wall parts 30 directed upwards along the entire peripheral edge, the upper edge 31 of which engages in a groove-shaped depression 32 of a cover part 33. This shape ensures high mechanical strength and a large soldering area. For pressure stability, the cover part 33 has a curvature 34.

16 shows a connection box 5 with an end 2 * of a flat tube 2 fastened therein, in which a cover part, viewed in cross section, has the shape of a circular section which is larger than a semicircle. In this cover part 35 there is a base part 36, which is designed as a flat plate with outwardly directed connecting pieces and is soldered to the cover part 35 at its lateral edges. When assembling this unit, the procedure is such that the base part 36, which is already provided with the flat tubes 2, is introduced into the cover part 35 in the region in which the cover part 35 has its greatest clear width, and then the cover part 35, in FIG. 16 seen, is moved upwards, so that the lateral edges of the bottom part 36 come to rest on the inner wall of the cover part 35.

Fig. 17 shows an embodiment variant of Fig. 8, the difference being that the connection box 5 consists of square tubes, namely an outer tube 37 and an inner tube 38, the outer tube 37, the openings 20 for receiving the pipe ends 2 * and the diametrically opposite openings 21 for carrying out a tool.

Fig. 18 shows an enlarged view of the connection arrangement of the bottom part 15 and the pipe end 2 * in Fig. 5. Before inserting the pipe end 2 * into the opening 16 in the bottom part 15, the pipe end 2 * has an outer dimension that is slightly less than that Opening 16. This allows the pipe end 2 * to be easily inserted into opening 16. With the help of a tool 39, for example in the form of a mandrel, the pipe end 2 * is expanded radially, so that there is a secure contact in the opening 16 against the base part 15. The tool 39 is preferably shaped in such a way that the area of the pipe end 2 * located within the connection box is given an oversize in relation to the opening 16 in the base part 15. When the heat exchanger is soldered, a cohesive connection takes place along the entire contact surface of the pipe end 2 * and the base part 15 and solder meniscuses 40 are formed to the side of the base part 15.

In all the illustrated embodiments, the parts forming the junction boxes 5 and the flat tubes are made of solder-plated material, the Flat tubes 2 are solder-plated on both sides because of the support webs 14 located therein. Even with the components that form the connection boxes 5, it is advisable to use solder-plated material on both sides in some design variants, in particular in the embodiments according to FIGS. 1 to 8, 12 and 15 to 18. Although in FIG. 2 the pipe ends 2 * are included are shown in a circular cross section, an oval shape of the connecting piece or openings and pipe ends is of course also possible.

Claims (19)

1. A heat exchanger, particularly a refrigerant condenser with a plurality of parallel flat tubes (2) and undulating fins (3) disposed between the flat tubes (2), the ends (2*) of the flat tubes (2) being connected to corresponding apertures in the tube plate (6, 15) of manifolds (5) consisting of solder-plated material and are soldered to the manifolds, characterised in that the flat tubes (2) likewise consist of a material which is solder-plated on both sides and in that there are in the flat tubes (2) bracing webs (14) which are, by means of the solder, connected to the flat tubes (2) by self-substance joints, and in that the ends (2*, 2**) have a circular cross-section and in that at the ends (2*, 2**) of the flat tubes (2), in the region of the tube plate (6, 15) of the manifolds (5) there is a portion which is a radial press fit between tube end (2*, 2**) and tube plate (6, 15).
2. A heat exchanger according to claim 1, characterised in that the flat tubes (2) are welded aluminium tubes.
3. A heat exchanger according to one of claims 1 or 2, characterised in that on the flat tubes (2) the round ends (2*, 2**) are integrally formed with no transition zone.
4. A heat exchanger according to one of claims 1 or 2, characterised in that a short transition zone is provided between the flat tube (2) and the round end (2*).
5. A heat exchanger according to claim 1, characterised in that there are around the apertures (4) in the manifolds (5) connecting unions (9, 24, 27, 28) which are directed into the manifolds (5) or at the undulating fins (3).
6. A heat exchanger according to claim 1 or 5, characterised in that the ends (2*) of the flat tubes (2) are disposed in apertures (4, 16) in the manifolds (85) and in that the portion with the radial press fit is formed in the region of the tube plate by a radial widening out of the ends (2*).
7. A heat exchanger according to claim 5, characterised in that the connecting unions (27) are fitted into the ends (2**) of the flat tubes and in that the radial press fit between tube end and tube plate is created by radial compression of the tube ends.
8. A heat exchanger according to one of the preceding claims, characterised in that the manifolds (5) consist of aluminium solder plated on both sides.
9. A heat exchanger according to one of the preceding claims, characterised in that the manifolds are constructed as a one-piece tube (23, 26).
10. A heat exchanger according to claim 9, characterised in that the tube (23) has a welded seam (25) on its side which is diametrically opposite the tube ends (2*).
11. A heat exchanger according to one of claims 6 to 7, characterised in that the manifolds (5) consist of two tubes (19, 22; 37, 38) fitted into each other concentrically, the outer tube (19, 37) having apertures (21) diametrically opposite the apertures for receiving the tube ends (2*) and in that the apertures (21) are masked by the inner tube (22, 38).
12. A heat exchanger according to one of claims 1 to 8, characterised in that the manifolds (5) have in each case a plate part (6, 15, 29, 36) and a cover part (7, 7*, 7**, 17, 33, 35) which are soldered to one another at the connecting surfaces.
13. A heat exchanger according to claim 12, characterised in that cover parts (7, 7*, 7**,, 17, 33) and plate parts (6, 15, 29) have overlapping and/or interengaging portions (12 or 31 and 32).
14. A heat exchanger according to one of the preceding claims, characterised in that flow deflecting means (8, 18) are disposed in the manifolds (5).
15. A heat exchanger according to claim 14, characterised in that the flow deflecting means are formed by angled-over portions (8) of the cover parts (7*, 7**).
16. A heat exchanger according to claim 14, characterised in that the flow deflecting means are formed by separators (18) inserted between cover portions (17).
17. A heat exchanger according to one of claims 1 to 4, characterised in that the flat tubes (2) are at their ends (2*, 2**) re-shaped into a circular or oval cross-section.
18. A heat exchanger according to one of claims 1 to 4, characterised in that the flat tubes (2) consist of a tube of circular or oval cross-section and which, in the region between the ends (2*, 2**), are pressed together so that their cross-section becomes that of a flat tube having parallel side walls.
19. A heat exchanger according to claim 17, characterised in that the flat tubes (2) consist of an extruded profile section which has over its total non-shaped length at least one bracing web (14) between the parallel side walls.

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