DE10103584A1 - Heat exchanger with fins and flat tube block has four-sided frame with cross section including grooves and inner and outer longitudinal and transverse walls - Google Patents

Abstract

The heat exchanger has a four-sided frame (7), which has an open cross section including grooves and inner and outer longitudinal and transverse walls. Its cross section is open to the collection or diversion box (5) and can take a seal for the collection box. Such a frame is fitted at both ends of the fin and tube block.

Description

The invention relates to a heat exchanger for motor vehicles with a fin Flat tube block, consisting of flat tubes, in opposite collection - Or deflection boxes open and arranged with between the flat tubes Ribs, the ends of the flat tubes are expanded so that they at least have a separating cut that divides the ends of the flat tubes into two parts, the are bent so far that the long sides of the widened ends with each other are connected.

The invention further relates to a method for producing a heat exchanger for motor vehicles, the flat tubes of which are cut at both ends Turning are expanded; which with the interposition of ribs into one Ribbed tube block are assembled so that the long sides adjacent ends of the expanded flat tubes lie against each other; after that a four-sided frame around which one end of the flat tubes of the finned tube Blocks and the other four-sided frame around the other end of the flat tubes of the finned tube block, after which the heat exchanger in one Brötofen is brought.

The heat exchanger described corresponds to that previously unpublished Registration DE 100 19 268.8.

It has long been known to use the expanded ends of the finned tube block to put a frame that serves to attach the collecting box. This The state of the art can in principle, for example, DE-Gbm 15 19 203 or are taken from CH 378 353.

In connection with the so-called all-aluminum construction of the Heat exchangers for motor vehicles have been experiencing this state of the art for some time a renaissance. The requirement is behind the all-aluminum construction according to the purity of the material, the expenses for the Reduce recycling.

From a functional point of view, however, the use of collection boxes is over Plastic, which is inexpensive to manufacture by injection molding, is essential more advantageous. It will therefore continue to play a role in practice because a number of additional functions, such as the attachment of mounting elements, Connection pieces, measuring control elements etc. are much easier Have plastic collection boxes realized. With collection boxes from For these functions, aluminum requires significantly more individual parts  must first be manufactured and then attached to the collection box, these are usually soldered on.

Furthermore, there are still all-aluminum heat exchangers certain difficulties, the solder joint between the collector or Deflection boxes and the extended ends of the flat tubes to get tight. Problem areas that tend to leak are still where have adjacent flat tube ends edges, which are from manufacturing Reasons must have a radius - albeit a very small one.

In DE 195 43 986 A1, FIG. 10, it has already been proposed to solder a frame at the ends in the case of rectangularly drawn-in tube ends, in which plastic collecting boxes are fastened. The solution shown there seems to be somewhat problematic in terms of production technology because the prefabricated frame is fixed in its dimensions and the solder-plated pipe ends lose their solder plating during soldering, which means that the ends of the flat tubes after soldering have a smaller scope than before soldering. The slight differences on the individual tube add up in a tube-fin block, so that a gap is created between the frame and the tube-fin block that cannot be filled with solder. This creates tightness problems.

The object of the invention is the heat exchanger from the preamble to transform so that it can be equipped with plastic collection boxes can to achieve a very low overall weight. The Manufacturing process should lead to low manufacturing costs.

The solution according to the invention for the heat exchanger is that a four-sided frame, which has a gutter-like, inner and outer longitudinal and Having transverse walls and open towards the collection or deflection box Has cross-section for receiving a seal and for mechanical Attachment of the edge of the collecting or deflection box is suitable both ends of the finned flat tube block is arranged, at least the inner transverse walls are closer together than that in the direction of the width of the not yet soldered finned tube block Measure between the ends of the first and last flat tube so that the two Parts of at least some flat tube ends in the elastic range through the Cross walls are compressible.  

The manufacturing process sees in connection with the generic term according to the invention that when plugging the frame in the direction perpendicular to a prestressing force on the long sides of the flat tubes on the ends of the finned Pipe blocks are exercised covering the ends of at least some flat tubes compressing the elastic range.

The following is achieved by these features.

The prestressing of the pipe ends by their compression in the elastic Area causes the melting of the Solder plating is easily compensated for. Process reliability when soldering significantly improved.

The heat exchanger described in the preamble, the so-called belongs to the "tube sheetless" genus, which therefore has no tube sheets and therefore has a low weight and low use of materials According to the invention, quite simply with collecting or deflection boxes made of plastic be equipped, which also weigh significantly less than such Have aluminum. This makes the total weight of the heat exchanger significantly reduced. In addition, the possibility was created that, exactly as with plastic collection or deflection boxes that are used for heat exchangers Pipe trays are provided, the same in future also for heat exchangers without Tube sheets are to be used. At such known collection or Deflection boxes are equipped with a variety of additional functions Invention has now been transferred to heat exchangers without tube sheets are. These additional functions are known in the art by means of injection molding Collection or deflection boxes realized. The heat exchanger according to the invention has, compared to those that have aluminum collection boxes, a slightly larger space requirement due to the frame, however compared with the usual heat exchangers with tube sheets and header boxes Plastic was also reduced in space because, according to the invention, the Frame can rest directly on the pipe ends.

Heat exchangers which have the features of claim 2 or 3 to 6, also lead to improved solder connections in terms of tightness because the means, like elevations on the inner longitudinal walls of the gutter-like Frame, or the projections on the upper longitudinal edge of the longitudinal walls exactly were arranged where the leakage problems in the prior art  occur, namely at the joints between the long sides of the flat tubes, more precisely, where the long sides merge with the narrow sides. As an alternative to the elevations, the inner edge can be on the upper longitudinal edge Longitudinal walls also a continuous, inward, slight Turn are provided. The radii in the transition area from the Long sides to the narrow sides of the flat tubes do not necessarily have to be that way be made small as before, so that there are further advantages in terms of production technology result. Materials (especially aluminum) can be used that do not have particularly good forming properties and that is why are cheaper.

The four-sided frame can be made from a U-shaped profile a frame is bent and welded at the seam. With that you can achieve significant material savings.

Alternatively, the four-sided frame can also be produced by deep drawing become, whereby a higher dimensional accuracy can be realized. That falls Inner part of the frame as waste, which is the case with the variant mentioned first is to avoid.

Other features are part of the claims.

Furthermore arise Features and effects from the following description of Embodiments that are essential for the present invention when in doubt could be.

Show it:

Fig. 1 cut perspective partial view of the heat exchanger;

Fig. 2 is an exploded view of Fig. 1;

Fig. 3 is partial side view of the first embodiment in Figures 1 and 2.

Fig. 4 section AA of Fig. 3;

Fig. 5 section BB of Fig. 3;

Fig. 6 detail "X" from Fig. 4;

Fig. 7 detail "Y" of Fig. 5;

Fig. 8 section CC of Figure 4, the first variant.

FIG. 9 section CC from FIG. 4, second variant;

Fig. 10 perspective view of a frame;

Fig. 11 to Fig 10 - according to another manufacturing method.

Fig. 12 is similar to Figure 1 but with additional elevations.

Fig. 13 is similar to Figure 2, also having elevations.

Fig. 14 modification of the third embodiment;

Fig. 15, the frame of the third embodiment;

Fig. 16 of the frame with a further modification;

Fig. 17 detail E of Figure 1 with other surveys.

The heat exchanger 1 shown is an air-cooled charge air cooler or a coolant cooler for motor vehicles. The cooling air passes through the ribs 3 arranged between the flat tubes 2 and cools the charge air or the coolant flowing in the flat tubes 2 . The ribs 3 - tube 2 - block and the frame 7 of the heat exchanger 1 consist of solder-plated aluminum sheet. The collecting box 5 is made of plastic as an injection molded product. The ends 4 of the flat tubes 2 are widened in that a cut 20 is first made in their narrow sides 14 , after which the two tube parts are bent outwards. This was described in detail in the applicant's previously unpublished patent application DE 100 19 268.8, to which reference is hereby expressly made. Figs. 1 and 2 show only one end of the heat exchanger 1. It goes without saying that an identical or similar collecting or deflecting box 5 is arranged at the other end of the heat exchanger, or at the other end 4 of the flat tubes 2 , which, exactly as shown, is mechanically fastened in the frame 7 . The finned 3 -tube 2 -block is assembled as shown. The longitudinal sides 6 form a connecting surface at the ends 4 of adjacent flat tubes 2 . After assembly, the channel-like frames 7 are pushed onto both ends of the ribs 3 - flat tube 2 - block, so that they hold the entire block together. Since the distance A between the transverse sides 19 of the frame 7 is slightly smaller than the dimension B measured in the direction of the block width ( FIG. 5) between the longitudinal sides 6 of the first and last flat tube in the block, at least some of the flat tube ends 4 become through the pushed-on frame 7 biased, that is, they are compressed in the direction of the block width in the elastic range. A force is exerted on the ends 4 of the tube-fin block in the direction of the arrows P ( FIG. 2). In order to make it easier to slide the frame 7 on, it is advantageous if the inner transverse sides 19 are provided with a slight inclination inwards. This has been shown in principle in the sketch belonging to FIG. 16 in a section through the transverse side 19 . The frame 7 is pushed in the direction of the arrow P, the lower radius on the frame 7 also being advantageous in order to facilitate the attachment of the frame 7 . There is also no reason not to equip the inner longitudinal sides 12 of the frame 7 with a slight inclination inwards. However, it should be emphasized that the inclination is not absolutely necessary because the application of the pretensioning force to the tube-fin block and thus the compression in the elastic range can also be carried out by means of the device which is known to be required for the plugging process.

It is also understood that the frame 7 with its inner longitudinal and transverse walls 12 ; 19 ( FIG. 10) are pushed so far over the ends 4 of the flat tubes 2 that the separating cut 20 or the bending area in the flat tube ends 4 is completely covered, as can be seen in particular from FIGS . 3, 4 and 5 , In this state, the block is soldered together in the soldering furnace. The inner longitudinal walls 12 of the frame 7 are also firmly and tightly connected to the narrow sides 14 of the flat tube ends 4 , as are the inner transverse sides 19 to the long sides 6 of the flat tubes 2 arranged outside in the block. Alternatively, the end of a side part 21 can also be located between the inner transverse sides 19 and the mentioned longitudinal sides 6 , as is described further below.

It is also apparent from FIGS. 4 and 5 that are present in the flat tubes 2 of this embodiment, the inner inserts 25. This measure is intended in particular for charge air coolers.

After the soldering process, the collecting boxes 5 made of plastic can be attached. For this purpose, the seal 11 ( FIG. 2) is first inserted into the channel-like frame 7 . Then the collecting box 5 is added with its edge 10 and by bending the tabs 18 on the outer longitudinal and transverse walls 16 , 17 of the frame 7 , the collecting box 5 is held firmly and tightly in the frame 7 . In other designs, not shown, the seal 11 has been injection molded directly onto the edge 10 of the collecting tank 5 . Furthermore, no tabs 18 were used for the mechanical fastening of the collecting box 5 . Instead, the outer longitudinal and transverse walls 16 , 17 were deformed in a wave-like manner. Both measures have long been state of the art in heat exchangers with tube sheets. They are also suitable in the present context.

The heat exchangers 1 have side parts 21 . In FIGS. 8 and 9 are two different constructions of the mounting of the side members 21 shown regard. In FIG. 8, the side part 21 terminates at the bottom of the channel-like frame 7 and is soldered there. The inner transverse wall 19 of the frame 7 is soldered to the longitudinal side 6 of the end 4 of the outermost flat tube 2 . In Fig. 9, however, the side part 21 has a bevelled edge 22 and extends with its bent end between the transverse wall 19 of the frame 7 and the aforementioned longitudinal side 6 of the flat tube 2.

In FIG. 10, all elements have been provided with the reference numerals which have been used above with regard to the frame 7 . The frame 7 was produced by deep drawing from a sheet metal blank. The area enclosed by the frame 7 falls as waste. A U-profile semifinished product was selected as the starting material for the frame shown in FIG. 11, which, as shown, was bent and welded in the seam 15 . Cutouts were previously made in the outer longitudinal and transverse walls 16 , 17 to produce the tabs 18 .

In FIG. 7, the area between the adjacent longitudinal sides 6 of adjacent flat tube ends 4 , in which there are often problems with tight solder connections, is designated by P. In order to achieve significant improvements there, the explanations according to FIGS. 12 to 16 are proposed. FIGS. 12 and 13 differ from Figs. 1 and 2 only in that the trough-like frame 7 are arranged projections 13 at the longitudinal edges of the inner longitudinal walls 12. The other reference numbers have therefore not been used. The projections 13 are located where two longitudinal sides 6 of adjacent flat tube ends 4 are connected. They were bent inwards and thus cover point P ( FIG. 7).

Fig. 14 shows a detail, in which the projections 13 are formed in contrast, as the vertical studs or the like on the inside of the longitudinal walls 12 of the frame 7. (see also Fig. 10)

In Fig. 15, the projections 13 have been replaced by a bent, continuous edge 23 on the inner longitudinal sides 12 of the frame 7 , which is cheaper in terms of tools.

Fig. 16 shows the frame 7 shown in FIGS. 12 and 13 as a single part. The associated sketch illustrates in a cutout how the frame 7 is attached to the ends 4 of the tube-fin block. The separated parts 2 a, 2 b of the flat tube ends 4 are pressed together in the elastic region. The inner transverse walls 19 have a slight inclination inwards, so that the pretensioning force is transmitted when plugged on. This process is usually carried out using special devices.

A further idea was realized in FIG. 17, which is particularly useful for somewhat longer frames 7 in order to maintain their dimensional stability. For this purpose, 12 transverse webs 24 were provided between the inner longitudinal walls, which are retained from the cutout in frames 7 produced by deep-drawing.

Claims (16)

1. Heat exchanger for motor vehicles with a finned flat tube block, consisting of flat tubes ( 2 ) which open into opposite collecting or deflection boxes ( 5 ) and with fins ( 3 ) arranged between the flat tubes ( 2 ), the ends ( 4 ) of the flat tubes ( 2 ) are expanded in such a way that they have at least one separating cut ( 20 ) which divides the ends ( 4 ) of the flat tubes ( 2 ) into two parts ( 2 a; 2 b), which are bent so far that the Long sides ( 6 ) of the widened ends ( 4 ) can be connected to one another by means of soldering, characterized in that a four-sided frame ( 7 ) which has a channel-like, inner and outer longitudinal and transverse walls ( 12 , 19 , 16 , 17 ) and for Collection or deflection box ( 5 ) towards, has an open cross section, which is suitable for receiving a seal ( 11 ) and for mechanically fastening the edge ( 10 ) of the collection or deflection box ( 5 ), at both ends 4 of the ribbed flat tube Arranged blocks et, whereby at least the inner transverse walls ( 19 ) have a smaller distance (A) from each other than the dimension (B) lying in the direction of the width of the not yet soldered finned tube block between the ends ( 4 ) of the first and last flat tube ( 2 ) or such a distance (A) that the two parts ( 2 a; 2 b) at least some flat tube ends 4 can be compressed in the elastic region by the transverse walls ( 19 ). 2. Heat exchanger according to claim 1, characterized in that the inner, with the circumference of the expanded pipe ends ( 4 ) connected longitudinal walls ( 12 ) of the frame ( 7 ) have means ( 13 , 23 ) suitable for leaks in the solder joint between the longitudinal walls ( 12 ) and to suppress the narrow sides ( 14 ) of the flat tubes ( 2 ). 3. Heat exchanger according to claim 2, characterized in that the means consist of spaced on the longitudinal walls ( 12 ) inwardly directed elevations ( 13 ); the distances coincide with the distances between the adjacent longitudinal sides ( 6 ) of adjacent flat tube ends ( 4 ), so that the elevations ( 13 ) with the joints ( 26 ) of two longitudinal sides ( 6 ) of adjacent flat tube ends ( 4 ) where the longitudinal sides ( 6 ) go to the narrow sides ( 14 ), correspond to counter the leak in this area. 4. Heat exchanger according to claim 2, characterized in that the means consist of projections arranged on the upper longitudinal edges of the longitudinal walls ( 12 ), which are bent inwards in order to counter the leaks. 5. Heat exchanger according to claim 2, characterized in that the means consist of a short, inward bend ( 23 ) of the upper longitudinal edge of the longitudinal walls ( 12 ). 6. Heat exchanger according to claim 2, characterized in that the means a Combination of the agents from claims 3, 4 and 5. 7. Heat exchanger according to claim 1 or 2, characterized in that the channel-like frame ( 7 ) is a part produced by deep drawing from a sheet metal blank. 8. Heat exchanger according to claim 1 or 2, characterized in that the channel-like frame ( 7 ) is made from a U-profile which is bent into a frame ( 7 ) and welded at the interface ( 15 ). 9. Heat exchanger according to claim 1 or 2, characterized in that the channel-like frame ( 7 ) is composed of several parts, the inner longitudinal and transverse walls ( 12 , 19 ) on the one hand and the outer longitudinal and transverse walls ( 16 , 17 ) belong to the other part. 10. Heat exchanger according to one of claims 1 to 9, characterized in that the frame ( 7 ) for mechanical fastening in its outer longitudinal and transverse walls ( 16 ; 17 ) has tabs ( 18 ) or other configurations which are suitable by deformation, to keep the edge ( 10 ) of the collection or deflection boxes ( 5 ) tight and tight. 11. Heat exchanger according to one of the preceding claims, characterized in that the seal ( 11 ) on the edge ( 10 ) of the collecting or deflecting box ( 5 ) is injection molded, or is used as an individual part in the channel-like frame ( 7 ). 12. Heat exchanger according to one of the preceding claims, characterized in that the inner ( 12 , 19 ) and the outer longitudinal and transverse walls ( 16 ; 17 ) of the channel-like frame ( 7 ) have the same or a different height, at least the inside transverse walls ( 19 ) have an inclination towards the tube-rib block. 13. Heat exchanger according to one of the preceding claims, characterized in that the heat exchanger ( 1 ) has side parts ( 21 ) and that the ends of the side parts ( 21 ) either end at the bottom of the frame ( 7 ), the transverse side ( 19 ) directly with the Long side ( 6 ) of the outermost flat tube end ( 4 ) is connected, or that the ends of the side parts ( 21 ) between the inner transverse side ( 19 ) of the frame ( 7 ) and the long side ( 6 ) of the outermost flat tube end ( 4 ) are arranged, wherein the distance (A) between the transverse sides ( 19 ) takes into account the thickness of the side parts ( 21 ). 14. A method for producing a heat exchanger ( 1 ) for motor vehicles, the flat tubes ( 2 ) are expanded at both ends ( 4 ) by means of cutting and bending; which are assembled with the interposition of fins ( 3 ) to form a fin-tube block, so that the longitudinal sides ( 6 ) of adjacent ends ( 4 ) of the expanded flat tubes ( 2 ) abut one another; then a four-sided, channel-like frame ( 7 ) is placed around one end of the flat tubes ( 2 ) of the finned tube block and the other four-sided frame ( 7 ) around the other end of the flat tubes ( 2 ) of the finned tube block, After which the heat exchanger ( 1 ) is brought into a soldering furnace, characterized in that when the frame ( 7 ) is put on by the frame ( 7 ) itself, a pretensioning force on the ends in the direction perpendicular to the longitudinal sides ( 6 ) of the flat tubes ( 2 ) ( 4 ) of the finned tube block is exerted, which compresses the ends ( 4 ) of at least some flat tubes ( 2 ) in the elastic region.

• -

15. The method according to claim 14, characterized in that the mechanical connection by bending tabs ( 18 ) on the outer longitudinal and transverse walls ( 16 ; 17 ) of the frame ( 7 ) on the edge ( 10 ) of the collecting or deflecting box ( 5 ) or by laterally pressing the outer longitudinal and transverse walls ( 16 ; 17 ) of the frame ( 7 ) onto the edge ( 10 ) of the collecting or deflecting box ( 5 ). 16. The method according to claim 14 or 15, characterized in that the frame ( 7 ) is formed from a sheet metal blank or from a U-profile by means of bending and welding in the seam ( 15 ).