EP0479012A1 - Heat exchanger - Google Patents

Abstract

2.1. In heat exchangers, in particular water-to-air cooling heat exchangers, it is known to arrange corrugated rib elements between flat tubes which end at a distance from the tube plates. This distance serves inter alia for the application of a silicone layer on the opposite tube plates after the hard/soft soldering process. 2.2. In the new heat exchanger (1a, 1b, 1c), spacers (14, 15, 30, 60) are provided in the gap region between the ends of the corrugated rib elements (9) and the tube plates in order to avoid widening the flat tubes (6). The novel heat exchanger is also able to withstand relatively high overpressure stresses of, e.g., approx. 4 bars. 2.3. Water-to-air cooling heat exchangers for motor vehicles. <IMAGE>

Description

The invention relates to a heat exchanger, in particular a water / air cooler for internal combustion engines, with a plurality of flat tubes which are arranged next to one another in at least one row and are sealed at both ends in tube sheets, and with corrugated fin elements which run between the side walls of adjacent flat tubes and which are fixed to the side walls end at a distance from the tube sheets.

In order to ensure the sealing of the flat tubes with respect to the tube sheets, it is known from DE-OS 26 24 879 to equip the tube sheets with elastic collar seals and to place end plates on the ends of the corrugated fin elements soldered to the side walls of adjacent tubes, on which sealing lips of the collar seals are used Plant can come. In contrast to heat exchangers of the type mentioned at the outset, the corrugated fin elements in this construction each extend as far as the tube sheets or their seals, without leaving a distance.

On the other hand, heat exchangers of the type mentioned provide (DE-GM 86 30 847) to allow the fins of a fin block to end at a distance from the tube sheets, so that a gap is formed between these ends of the fin elements and the tube sheets, through which a gap is formed just extend the pipes. As a result, the seams between the tubes and the tube sheets remain more easily accessible, so that an additional seal can be attached in the area of the tube sheets even after the radiator has been soldered. Leaving this gap open not only makes it possible to attach a seal, but also simplifies any need to remedy a leak in the area of the tube / tube sheet connections that may become necessary later.

When using flat tubes, under the influence of an increased load required for certain applications, e.g. high pressures in the coolant circuit and / or a high number of internal pressure changes, stability and / or tightness problems occur with such a heat exchanger, in particular if instead of a fin block constructed in the manner of a lamellae, individual corrugated fin elements are provided between the flat tubes and extend essentially parallel to the flat tubes. An increase in the material thickness of the individual components is unsuitable for certain applications, for reasons of weight alone, although it must also be taken into account that the required heat conduction function also severely limits the selection of the material. The thin-walled flat tubes are usually made of aluminum or a non-ferrous metal.

The invention has for its object to develop a heat exchanger of the type mentioned in a simple manner so that it can be operated reliably and trouble-free even with the use of flat tubes and corrugated fin elements under increased pressure requirements.

The object is achieved for a heat exchanger of the type mentioned in that in the gap area between the ends of the corrugated fin elements and the tube sheets an expansion of the flat tubes preventing support means are provided. It has been shown that this configuration effectively prevents expansion of the flat tubes caused by high excess pressure. This measure, which involves only little effort, is sufficient to keep the heat exchanger functional even at an overpressure of approx. 4 bar without the corrugated fin elements buckling due to an expansion of the flat tubes or loosening the hard or soft solder connection from the side walls of the Peel flat tubes or even leakages occur. It is not necessary that materials and wall thicknesses other than the usual are used for the flat tubes. This configuration is particularly advantageous if there is only a small number of corrugated fins between the flat tubes. It is known that for reasons of skill, a larger number of corrugated fins is used today than would be required for the heat transfer performance.

In an embodiment of the invention, the support means are assigned to each end region of the corrugated fin elements and are designed as spacers which run approximately parallel to the tube sheets and run between the side walls of adjacent flat tubes. The spacers secure the distance between the side walls of adjacent flat tubes in this area, so that the expansion of the flat tubes caused by an overpressure load is largely prevented. The spacers can rest against the side walls in the unloaded state of the flat tubes or can be arranged with little play. The latter allows a certain widening of the flat tubes, but this cannot lead to an impairment of the cooler structure.

In a further development of the invention, the end region of the corrugated fin elements, which is fixed on both sides on the side walls of adjacent flat tubes, is provided as a spacer, within which the individual corrugated fins are gathered and lie tightly against one another. This further development is associated with particularly low additional manufacturing outlay, since the gathering can already be integrated into the folding process for the corrugated fin elements. Due to the gathering, the closely spaced corrugated ribs have an increased height Stiffness that is sufficient to support the flat tube side walls.

In a further embodiment of the invention, the spacers are formed as teeth of support combs which are arranged essentially parallel to the tube sheets at the ends of the corrugated fin elements. This configuration has the advantage that the support means can also be added subsequently, i.e. after completion of an unsupported heat exchanger, attached or existing, unsupported heat exchangers can be easily retrofitted with these support means. Such support combs can be inserted from both sides between the flat tubes.

In a further embodiment of the invention, spacers are provided in the form of intermediate floors, which are each arranged parallel to the tube sheets at the ends of the corrugated fin elements. The intermediate floors can expediently have a shape corresponding to the tube sheets and can thus be manufactured in the operation already provided for the tube sheets.

In a further development of the invention, additional support means are provided approximately in the middle between the end support means. It has been shown that just an additional support in this area supports the effect of the end support means advantageous. Thus, the flat tubes cannot expand beyond a desired extent even in this area furthest from the stabilizing tube sheets, even if the stability of the corrugated fin elements alone is not sufficient to prevent the flat tubes from expanding in this area.

In a further development of the invention are provided for additional support of the heat exchanger against an expansion of the flat tubes with their legs outwardly facing side boundary parts, the narrow sides of which are bent in a C-shape. This design of the side boundary parts advantageously supports the formation of a square frame together with the tube sheets even further, the effect of the supporting means in the end regions of the corrugated fin elements that prevents the flat tubes from expanding. This is primarily because the side delimitation parts can absorb higher transverse forces than, for example, flat or U-shaped cross-section delimitation parts due to the C-shaped fold.

Preferred embodiments of the invention are shown in the drawings and are described below.

• Fig. 1 einen Wasser/Luft-Kühler für eine Brennkraftmaschine in einer Ansicht,
• Fig. 2 einen als Abstandshalter dienenden Zwischenboden für den Wasser/Luft-Kühler der Fig. 1,
• Fig. 3 einen alternativ zu dem Zwischenboden der Fig. 2 verwendbaren Abstützkamm,
• Fig. 4 einen Teil eines Wasser/Luft-Kühlers, ausgerüstet mit dem Abstützkamm der Fig. 3, in einer perspektivischen Teilansicht,
• Fig. 5 eine perspektivische Teilansicht eines Teils des Wasser/Luft-Kühlers der Fig. 4 von der gegenüberliegenden Seite her gesehen,
• Fig. 6 ein Ausschnitt aus einem weiteren Wasser/Luft-Kühler mit gerafften Wellrippenelementen in einer Ansicht ähnlich Fig. 1 und
• Fig. 7 einen Querschnitt durch ein Seitenbegrenzungsteil des Wasser/Luft-Kühler der Fig. 1.

Show it:

• 1 shows a water / air cooler for an internal combustion engine in a view,
• 2 is a spacer serving as a spacer for the water / air cooler of FIG. 1,
• 3 shows a supporting comb that can be used as an alternative to the intermediate floor of FIG. 2,
• 4 shows a part of a water / air cooler, equipped with the supporting comb of FIG. 3, in a perspective partial view,
• 5 is a partial perspective view of part of the water / air cooler of FIG. 4 seen from the opposite side,
• Fig. 6 shows a detail from another water / air cooler with gathered corrugated fin elements in a view similar to Fig. 1 and
• 7 shows a cross section through a side delimitation part of the water / air cooler of FIG. 1.

A water / air cooler (1a) shown in Fig. 1 has two opposite water boxes (2, 3), each having an opening (4, 5) for water supply and drainage. Between the water boxes (2, 3), flat tubes (6) are arranged side by side in a row, the larger side surfaces of the adjacent flat tubes running parallel to one another. In Fig. 1 only the narrow end face of the flat tubes (6) pointing in the direction of flow can be seen. The tube sheets (7, 8) enclosed by the water boxes (2, 3) have suitable openings in a known manner for the passage of the flat tubes (6). They are folded over at the ends and firmly attached to adjacent side walls of the water tanks (2, 3). Corrugated fin elements (9) are inserted between the larger side walls of adjacent flat tubes (6), which adjoin intermediate floors (14, 15) at both end regions, as shown in FIG. 2. A gap (12, 13) remains between these intermediate floors (14, 15) and the adjacent tube sheets (7, 8).

The corrugated fin elements (9) are each soldered to the side walls of the flat tubes (6) and serve primarily for heat transport between the fluid flowing through the flat tubes (6) and the air flowing between the flat tubes (6). In addition, the corrugated fin elements (9) also have a certain stiffening function. The side closure of the water / air cooler (1a) forms a side limiting part (10, 11) with high bending strength.

The water / air cooler (1a) is usually assembled by inserting the flat tubes into the openings in the tube sheets (7, 8) and inserting the corrugated fin elements (9) between the flat tubes (6). Then the Fixing the flat tubes (6) to the tube sheets (7, 8) and the corrugated fin elements (9) to the side walls of the flat tubes (6) by a brazing process. In order to prevent tightness problems, especially in the area of the flat tube bushings through the tube sheets (7, 8), a seal is then assigned to the tube sheets. The area of the tube sheets (7, 8) should therefore still be accessible without major difficulties after the brazing process, which is why the corrugated fin elements (9) end at a distance from the tube sheets (7, 8) and each leave the gap (12, 13) there.

At very high overpressures in the flat tubes, as is desired in modern vehicle radiators, there can be strong transverse forces in the area of the ends of the corrugated fin elements (9), which can lead to an expansion of the thin-walled flat tube side walls in the area of the gaps (12, 13) , because it is not prevented by corrugated fin elements running between the side walls. The intermediate floors (14, 15), the shape of which can be seen in FIG. 2, are therefore inserted in the region of the ends of the corrugated fin elements (9) as supporting means. They essentially have the shape of a rail, in which parallel, slot-like openings (20) are arranged, the shape of which corresponds to the cross section of the flat tubes (6) and are guided through the latter. The shape of the intermediate plates (14, 15) therefore essentially corresponds to that of the tube plates (7, 8), so that the intermediate plates (14, 15) can preferably be produced by the same working process as the tube plates (7, 8). The intermediate floors (14, 15) are attached to the ends of the corrugated fin elements (9) and in each case delimit the gaps (12, 13) running parallel to the facing tube sheet (7, 8).

The areas (21) between the openings (20) form spacers which limit the distance between facing side walls of adjacent flat tubes to a certain value and thereby prevent the flat tubes (6) from widening too much under high overpressure loads.

It has been shown that the arrangement of additional support means in the area of the ends of the corrugated fin elements (9) is very effective with regard to the highest possible overpressure resistance. The simple way of equipping with support means, here with the intermediate floors (14, 15), in the area of the ends of the corrugated fin elements (9) makes pressure loads in the cooler of over 4 bar possible before the expansion of the flat tubes damages the function, such as leaks or detachment of the braze joints occurs.

In a further embodiment of a water / air cooler (1 b) shown in FIG. 4, a support comb (30) shown in FIG. 3 serves as such a support means, which in the area of the gaps (12, 13) at the ends of the Corrugated fin elements (9) is attached. Otherwise, this water / air cooler (1 b) corresponds in structure to that of the water / air cooler (1 a) shown in FIG. 4, the inclusion of the flat tubes (6) in the tube sheet (7) can be seen. 4 shows the side of the water / air cooler (1b) along which the end face (33) of the supporting comb (30) runs, FIG. 5 shows a section of the opposite side of this water / air cooler ( 1b). 5 therefore shows the individual teeth (31) of the supporting comb (30) which run between the side walls of adjacent flat tubes (6) and which can also be rounded at their free ends, which is not shown in the drawing. Such a rounding of the free ends facilitates the insertion of the comb and prevents damage to the pipes. The gaps (32) between the teeth (31) of the support comb (30) of FIG. 3 correspond in their width approximately to the distance between adjacent flat tube outer walls. The support combs (30) located at both ends of the corrugated fin elements (9) are each inserted with a press fit. They do not need to be soldered. If necessary, it can of course also be provided to choose the width of the openings (32) somewhat larger than the outer spacing of the side walls of a flat tube (6) and to fix the support combs (30) in a different way, in order to thereby expand the flat tubes within one to allow the width of the openings (32) of a certain area. The teeth (31) in turn serve according to the areas (21) of the intermediate floors (14, 15) as spacers between mutually facing side walls (6a, 6b) of adjacent flat tubes. The use of support combs (30) as a support means has the further advantage that this can also be done after the assembled flat tubes (6) and the tube sheets (7, 8) have been soldered. Existing heat exchangers can also be easily retrofitted with the support combs (30) and thus made usable for higher pressure loads. It is also possible to provide two support combs in both columns (12, 13), the prongs of which can be inserted into the spaces between the flat tubes from the opposite sides of the cooler.

FIG. 6 shows another embodiment of a water / air cooler (1c) which can be subjected to high excess pressure. In this case, coolers (1c) which are otherwise identical to the water / air coolers (1 a, 1 b) described above are used instead of intermediate floors (14, 15) or support combs (30) as support means end regions (60) of the corrugated fin elements (9) themselves. In the end regions (60) the individual corrugated fins are gathered and lie essentially close to one another, so that they are used for the side walls of the Flat tubes (6) receive a substantially increased support effect compared to the other areas of the corrugated fin elements (9). The gathering is preferably already integrated in the manufacturing process for the corrugated fin elements (9), in that the folding process for the workpiece on which the corrugated fin elements (9) are based is varied accordingly such that the individual corrugated fins come to lie close together in the end regions.

In this embodiment, therefore, no separate support means need to be made.

While, as explained above, the arrangement of support means in the end regions of the corrugated fin elements (9) is of the greatest importance for increasing the load resistance of the heat exchangers, the stiffening effect can be further advantageously supported by simple additional measures.

One possibility is a special shaping of the side delimitation parts (10, 11), which is shown in cross section for the side part (10) in FIG. 7. The side parts (10, 11) are shaped in a C-shape, the base side (72) running parallel to the flat tube side walls and adjoining the outermost corrugated fin element in such a way that the two legs (70, 71) each point outwards. In contrast to a conventional U-shape of the side parts (10, 11), the ends of the legs (70, 71) are folded over again at right angles and thus run approximately parallel to the base side (72). It turns out that this bending of the ends of the legs (70, 71), which can be done with little effort, has a very positive effect with regard to a further increase in the overpressure strength for such heat exchangers.

Furthermore, it has been shown that, if necessary, it is also advantageous to use a support means, as is already provided in the above-described manner in the end regions of the corrugated fin elements (9), also in the region of the central axis (16) shown in FIG. Air cooler (1 a, 1 b, 1 c) to be provided. This is because, in addition to the end regions of the corrugated fin elements (9) which are particularly sensitive to overpressure due to the gaps (12, 13), this central region (16) is also sensitive to stress since, taking into account a comparatively low stiffening effect of the thin-walled corrugated fin elements (9), it is the greatest distance from one of the stabilizing ones Has tube plates (7, 8). Of course, the insertion of a support comb (30) of the type shown in FIG. 3 along the central axis (16) is particularly simple here. The spacers which are also used in the gaps (12, 13) can be provided here as support means.

Further variants are conceivable, the arrangement of the support means in the region of the ends of the corrugated fin elements (9) ending at a distance from the tube sheets (7, 8) being important, without the flat tubes (6) extending their length over a larger section additionally need to be reinforced or stiffened on the inside or outside, whereby the heat exchanger can nevertheless withstand pressure loads of over 4 bar.

Claims (7)

1. Heat exchanger, in particular water / air cooler for internal combustion engines, with a plurality of tubes arranged next to one another in at least one row and with both ends sealed in tube sheets and with rib elements running between the adjacent tubes and ending at a distance from the tube sheets that the tubes are designed as flat tubes and the fin elements are corrugated fin elements, and that in the gap area between the ends of the corrugated fin elements (9) and the tube sheets (7, 8) support means (14, 15, 30,) preventing the flat tubes (6) from widening 60) are provided. 2. Heat exchanger according to claim 1, characterized in that the supporting means are assigned to each end region of the corrugated fin elements (9) and are formed as spacers which run approximately parallel to the tube sheets (7, 8) and which have adjacent flat tubes between the side walls (6a, 6b) (6) run. 3. Heat exchanger according to claim 2, characterized in that as a spacer each on the side walls (6a, 6b) adjacent flat tubes (6) on both sides fixed end region (60) of the corrugated fin elements (9) is provided, and that in this end region (60) the individual corrugated ribs are gathered and lie close together. 4. Heat exchanger according to claim 2, characterized in that the spacers are designed as teeth (31) in each case at least one support comb (30) which can be inserted transversely to the tube axes. 5. Heat exchanger according to claim 2, characterized in that intermediate floors (14, 15) are provided as spacers which Have slot-like openings (20) for the passage of the flat tubes (6) and rest with their areas (21) running between the openings (20) on the flat tubes. 6. Heat exchanger according to one of claims 1 to 5, characterized in that further support means are arranged approximately in the middle between the tube sheets (7, 8). 7. Heat exchanger according to one of claims 1 to 6, characterized by with its side walls of the corrugated fin elements (9) facing outward, by bending the narrow sides having a C-shaped cross section having side boundary parts (10, 11).

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