EP0505244B1 - Heat exchanger with tube bundle, more particularly for motor vehicle - Google Patents

Description

The invention relates to a heat exchanger of the type comprising a bundle of tubes arranged in at least one row and in which each tube has a body terminated by an end received in a collecting plate.

This collector plate, also called a "hole plate", is part of a water box which is mounted at one end of the bundle, the other end of this bundle most often being fitted with a similar water box.

Such heat exchangers are used in particular in motor vehicles with an internal combustion engine to constitute either an engine cooling radiator or a cabin heating radiator.

The tubes of the bundle are then traversed by a cooling fluid, generally brine, which circulates in a closed circuit and which is cooled by heat exchange with air passing through the exchanger.

Conventionally, the bundle tubes have a circular cross section, both at their body and at their ends.

However, to optimize the performance of heat exchangers of this type, and in particular to reduce the pressure losses undergone by the air passing through such an exchanger, tubes are also used, the body of which has a non-circular cross section, which is generally oblong, for example, flattened, oval, elliptical, etc.

Most often, the end of the tube has a cross section of a shape different from that of the body of the tube. It is generally less oblong than that of the body of the tube, even circular, and this to avoid a possible deformation of this end.

Indeed, as this sealing is often ensured by a compressed gasket between the end of the tube and a collar which surrounds the corresponding hole of the collector plate, the pressure exerted by the gasket would risk flattening the end of the tube .

Whatever the shape of the tubes used, and whatever the type of collector plate used, it must have a minimum of material, therefore a minimum spacing, between two adjacent holes to give it an appropriate mechanical strength and, in the case where the holes are provided with collars, for the production of these collets.

In addition, in document US-A-4,546,824, there is described a heat exchanger comprising a bundle of tubes able to be connected to a collector plate.

According to this document, the tubes have a body terminated by an end capable of being received in the collector plate, the ends being offset relative to the body.

As can be seen in the figures in this document, it is provided that the distance between the two ends of the two adjacent tubes is identical to that of the body of the tubes so as to be able to allow sufficient diametral widening of the end.

Under these conditions, it is difficult to optimize the center distances of the tubes, and this taking into account the dimensional constraints specific to the production of the heat exchanger, and in particular of its collector plate.

The object of the invention is in particular to overcome the drawbacks mentioned above.

It is, in particular, an object of the invention to improve the performance of heat exchangers of this type and to widen their possibilities of realization.

The invention proposes for this purpose a heat exchanger of the type defined in the introduction, in which at least two adjacent tubes of the bundle have a terminal center distance separating their respective ends which is different from a central center distance separating their respective bodies.

Because the terminal distance and the central distance have different values, whereas until now they had the same value, one can widen the possibilities of realization of the heat exchangers of this type and improve their performances.

In a first embodiment of the invention, the terminal center distance of the two adjacent tubes is greater than their central center distance.

Preferably, the two adjacent tubes in this case belong to two different rows of the bundle.

Thus, for a given center distance between two adjacent holes belonging to two different rows of the collector plate, and therefore corresponding to the terminal center distance defined above, the center distance of the tube bodies can be reduced, which makes it possible to reduce the width of the beam.

In this embodiment, the respective ends of the tubes of the bundle are advantageously each received individually in a hole in the collector plate, the latter having several rows of holes arranged so that the distance between two adjacent holes of two different rows corresponds at the terminal center distance of the tubes.

In another alternative embodiment of the invention, the terminal center distance of the two adjacent tubes is less than their central center distance.

It is thus possible to reduce the dimensions, in particular the width, of the collector plate.

In a first variant, the two adjacent tubes belong to two different rows of the bundle, which makes it possible to reduce the width of the collector plate. Advantageously, the tubes of the bundle are grouped by pairs of adjacent tubes, so that the respective ends of the two adjacent tubes of the same pair are received in the same hole of the collector plate, the latter comprising as many holes as pairs of tubes.

In another alternative embodiment, the two adjacent tubes belong to the same row of the bundle.

Advantageously, the tubes of the bundle are grouped by pairs of adjacent tubes, so that the respective ends of two tubes of the same pair are received in the same hole of the collector plate, the latter comprising as many holes as pairs of tubes.

This variant is particularly interesting because it makes it possible to reduce the length dimension of the collector plate.

In the various embodiments mentioned above, the bodies of the tubes of the bundle preferably have a cross section of generally oblong shape, while their ends have a cross section of less oblong shape, or even circular.

Of course, the invention could also be applied to heat exchangers in which the tubes have a circular section both at their body and at their ends.

In all the variants of the invention, the tubes can be assembled to the collector plate or plates by means of assembly techniques known per se, for example by means of a seal, by brazing, gluing, expansion, etc.

• la figure 1 est une vue partielle en coupe transversale d'un échangeur de chaleur selon une première forme de réalisation de l'invention;
• la figure 2 est une vue partielle en coupe transversale d'un échangeur de chaleur selon une seconde forme de réalisation de l'invention;
• la figure 3 est une vue schématique de dessus d'une presse destinée à mettre en forme les extrémités des tubes de l'échangeur de chaleur de la figure 2;
• la figure 4 est une vue partielle en coupe transversale d'un échangeur de chaleur analogue à celui de la figure 2;
• la figure 5 est une vue partielle en coupe transversale d'un échangeur de chaleur suivant une autre variante de réalisation;
• la figure 6 est une vue partielle en coupe suivant la ligne VI-VI de la figure 5;
• la figure 7 est une vue partielle en coupe suivant la ligne VII-VII de la figure 8 montrant un autre échangeur de chaleur selon l'invention;
• la figure 8 est une vue en coupe suivant la ligne VIII-VIII de la figure 7; et
• la figure 9 est une vue partielle en coupe transversale d'un échangeur de chaleur suivant une autre forme de réalisation.

In the description which follows, given only by way of example, reference is made to the appended drawings, in which:

• Figure 1 is a partial cross-sectional view of a heat exchanger according to a first embodiment of the invention;
• Figure 2 is a partial cross-sectional view of a heat exchanger according to a second embodiment of the invention;
• Figure 3 is a schematic top view of a press for shaping the ends of the tubes of the heat exchanger of Figure 2;
• Figure 4 is a partial cross-sectional view of a heat exchanger similar to that of Figure 2;
• Figure 5 is a partial cross-sectional view of a heat exchanger according to another alternative embodiment;
• Figure 6 is a partial sectional view along line VI-VI of Figure 5;
• Figure 7 is a partial sectional view along line VII-VII of Figure 8 showing another heat exchanger according to the invention;
• Figure 8 is a sectional view along line VIII-VIII of Figure 7; and
• Figure 9 is a partial cross-sectional view of a heat exchanger according to another embodiment.

We first refer to Figure 1 which shows a heat exchanger comprising a bundle consisting of a multiplicity of tubes 10 arranged in two rows and which shows two adjacent tubes belonging respectively to these two rows.

Each tube 10 has a body 12 having a non-circular cross section S1 which, in the example, is substantially elliptical. The body 12 is terminated by an end 14 which has been deformed to have a cross section S2 of non-circular shape and which, in the example, is substantially elliptical. Section S2 is less elongated than section S1, the long axis of the ellipse of section S2 being shorter than the long axis of the ellipse of section S1, while the small axis of section S2 is longer than the minor axis of section S1.

The body 12 and the end 14 of each tube 10 have a common generator 16 oriented towards the outside of the bundle.

It follows that the respective bodies 12 of two adjacent tubes 10 belonging to the two different rows are separated from each other by a central center distance A, while their respective ends 14 are separated from each other by a terminal center distance A ′ which is greater than A.

The bundle of the heat exchanger further comprises a multiplicity of fins 18 which extend parallel to each other and which each provide two rows of holes to allow passage to the bodies 12 of the tubes 10.

The ends 14 of the tubes 10 are received in a collector plate 20 which, in the example, is a metal plate comprising a core 22 of generally rectangular shape in which are arranged two rows of holes 24 each having a cross section of shape adapted to that of the end 14 of a tube 10. Each of the holes 24 is surrounded by a collar 26 turned towards the side of the fins 18.

The core 22 is surrounded, over its entire perimeter, by a folded edge 28 forming a groove and terminated by foldable legs 30. The seal between the ends 14 of the tubes and the holes 24 of the collector plate 20 is ensured by a seal 32 which comprises a core 34 of generally rectangular shape adapted to the shape of the core 22 of the collector plate 20. The core 34 has two rows of holes each surrounded by a compressible collar 36 suitable for being compressed between a hole 24 in the collector plate and the end 14 of the tube 10 received in the corresponding hole. The core 34 of the joint 32 is bordered, over its entire perimeter, by a bead 38 capable of being placed in the peripheral groove delimited by the folded edge 28 of the collector plate 20.

The heat exchanger further comprises a wall 40 of a water box comprising an open face of generally rectangular shape limited by a flange 42 capable of being introduced into the groove of the collecting plate 20 by compressing the bead 38 of the gasket. tightness under the action of the clamping lugs 30.

In the embodiment of FIG. 1, the collector plate 20 comprises, between two adjacent holes 24 of two different rows, a bridge of material 44 which, for reasons of mechanical resistance of the collector plate, and for producing collars 26 , cannot go below a minimum value. It follows that the center distance of the holes 24 of the collector plate, which corresponds to the terminal center distance A ′ mentioned above, cannot fall below a minimum value. Thus, thanks to the invention, for a center distance A ′ of minimum value, it is possible to produce a beam whose central center distance A is less than the terminal center distance A ′. This makes it possible to optimize the dimensions of the heat exchanger bundle for given dimensions of the collector plate or of the bundle.

At the other end of the bundle, the tubes 10 may have deformed ends similar to those of the ends 14 to receive a similar collecting plate provided with a water box wall. As a variant, the tubes 10 can be joined two by two by elbows, which avoids the presence of a second water box.

Reference is now made to FIG. 2 which shows another heat exchanger comprising, as in the case of FIG. 1, two rows of tubes 10 each of which has a body 12 of cross section S1 and one end 14 of cross section S2.

As in the case of FIG. 1, each of the tubes 10 comprises a generator 16 common to the body 12 and to the end 14. However, in the case of FIG. 2, the generators 16 of two adjacent tubes are arranged on the interior side of the beam, that is to say close to each other.

The heat exchanger of FIG. 2 comprises a collecting plate 46 comprising a core 48 of generally rectangular shape which provides a single row of holes 50 each of which has an oblong cross section suitable for simultaneously receiving the respective ends 14 of two adjacent tubes 10 belonging to two rows of the bundle. Each of the holes 50 is surrounded by a collar 52 turned towards the side of the fins 18.

The core 48 of the collector plate comprises, over its entire periphery, a folded edge 54 terminated by folding legs 56.

On the core 48 of the collector plate is applied a seal 58 of generally rectangular shape bordered by a peripheral bead 60 suitable for being received in the groove of the collector plate 46. The seal 58 comprises two rows of holes suitable for receive the ends 14 of the tubes 10. These holes are grouped in pairs, each pair of holes being surrounded by a collar 62 having substantially the shape of an 8 and suitable for being introduced into a collar 52 to seal between this collar and the two ends 14 received in this collar. The collar 62 has, in its middle, a material bridge 64 in the intermediate region between two adjacent tubes.

The material bridge 64 which forms part of the seal 58 has a narrower width than that of the material bridge 44 forming part of the collecting plate 20 of the heat exchanger of FIG. 1.

Given the small width of the material bridge 64 and the fact that the terminal center distance A ′ is less than the central center distance A, it is possible to produce a water box whose overall width is smaller than that of the water box of figure 1.

.If we designate by L the width of the body 12 along its largest dimension (that is to say the major axis of the elliptical section S1) and by L ′ the largest dimension of the end 14 (c ' i.e. the major axis of the elliptical section S2), and if we denote by e the difference between the centers A and A ′, we have the relation: $\text{L ′ / 2 + e = L / 2}$

.

Reference is now made to FIG. 3 which represents a tool 66 intended to conform the ends of the tubes of the bundle. This tool comprises a fixed central jaw 68 comprising, on two opposite sides, a series of half-impressions 70 whose shape corresponds to that of a half-ellipse of section S2. The tool further comprises two movable jaws 72 each of which is provided with half-impressions 70 similar to those of the central jaw 68. The half-impressions 70 of the central jaw 68 and of the lateral jaws 72 are separated two by two from a center distance E which corresponds to the center distance of the tubes within a row of the beam.

The ends 14 of the tubes 10 of the bundle have, before deformation, a cross section S1 identical to that of the body of the tube. By bringing the two lateral jaws 72 towards each other on either side of the central jaw 66, as indicated by the arrows F, the ends of the tubes are simultaneously deformed to arrive at the final section S2.

Referring now to Figure 4 which is a variant of the embodiment of Figure 2. In this figure, the elements common to those of Figure 2 are designated by the same reference numerals.

.Unlike the heat exchanger of Figure 2, each of the tubes 10 does not have a generator common to both its body 12 and its end 14. This means that we can have the relationship $\text{L ′ / 2 + e> L / 2}$

.

In the embodiment of Figures 5 and 6 to which we now refer, the heat exchanger comprises two rows of tubes 10 each of which comprises a body 12 having a non-circular cross section S1 which, in the example, is limited by two parallel edges 74 and two semi-circular edges 76 to form a so-called "flat" tube. Body 12 extends by a deformed end 14 having a non-circular cross section S2 which, in the example, is limited by two parallel edges 78, a flat inside edge 80 and a semicircular outside edge 82. The section S2 has a shorter length than section S1, but a larger width (Figures 5 and 6). The tubes 10 are grouped in pairs, so that the respective ends 14 of a pair of tubes are received in the same hole 50 of a collecting plate 46 similar to those of FIGS. 2 and 4. However, in this embodiment , the hole 50 is bordered by a collar 52 which extends from the side of the water box. Between two adjacent pairs of tubes 10 are disposed spacers 84 serving as cooling fins.

As in the case of FIGS. 2 and 4, the collecting plate 46 is surrounded by a folded edge 54 provided with foldable tabs 56 to receive the bead 42 of a wall of a water box 40. However, in this embodiment, it a simple seal 86 is provided which comes to rest in the bottom of the groove of the collector plate.

In the embodiment of FIGS. 5 and 6, the tubes 10 are plated by means of an easily fusible alloy, which makes it possible to braze each pair of ends 14 inside a hole 50 with the formation of a solder joint 88. The spacers 84 are also brazed between the pairs of adjacent tubes.

It should be noted that, in the embodiment of FIGS. 5 and 6, the terminal center distance A 'is also less than the central center distance A. However, this embodiment allows the width of the box to be further reduced. water because the two tubes of the same pair are in contact over their entire length.

We now refer to Figures 7 and 8 which show another heat exchanger comprising two rows of tubes 10. In this embodiment, the tubes are grouped in pairs within the same row. In the example, the body 12 of each tube has a non-circular cross section of substantially elliptical shape. On the other hand, the end 14 of each tube has a circular cross section.

The two ends 14 of a pair of tubes forming part of the same row are received in the same elongated hole 90 forming part of a collecting plate formed through the rectangular core 92 of a collecting plate 94 provided , around its periphery, with a folded edge 96. Each hole 90 has a characteristic shape obtained by the intersection of two circles, as shown in FIG. 7.

On the core 92 of the collector plate is disposed a seal 98 having a core 100 of generally rectangular shape suitable for being applied to the core 92 of the collector plate. The core 100 is surrounded by a bead 102 capable of bearing in the peripheral groove of the collector plate and forming a seal with the peripheral bead 42 of a wall 40 of the water box. The core 100 of the seal provides circular holes corresponding to the ends 14 of the bundle tubes. The holes made through the joint are grouped in pairs and surrounded by a collar 104 having the general shape of an 8. Each collar 104 is thus introduced into a hole 90 of the collector plate by enclosing the two ends 14 of the tubes d 'the same pair.

Thus, within the same pair of tubes, the terminal center distance B ′ of the ends 14 is less than the central center distance B of the bodies of the tubes. This makes it possible to have the ends of circular tubes while reducing the overall length of the water box since the collector plate has bridges of material 106 between the pairs of tubes in a row, and not between the tubes of a row as in the previous embodiments.

In the embodiment of FIG. 9, to which reference is now made, the tubes 10 have, as in the case of the Figure 2, a center distance A ′ less than the center distance A. In addition, each tube 10 has a generator 16, common to the body 12 and to the end 14, which is on the inside of the beam.

In this embodiment, the heat exchanger comprises a collector plate 108 of plastic material in which holes 110 are formed, each surrounded by a collar 112 directed towards the side of the fins 18 of the bundle.

Each of the collars 112 is provided with an annular groove 114 of a shape adapted to that of the end 14 of a tube in order to be able to accommodate said end. The latter is glued into the groove 114 by means of an appropriate adhesive 116, for example of the two-component type.

On the periphery of the collector plate 108 is also glued the peripheral bead 42 of a wall 40 of the water box, also made of plastic.

Although the invention has been described with reference to heat exchangers comprising tubes of non-circular cross section, it could also apply to such tubes.

Claims (10)

1. A heat exchanger comprising a bundle of tubes (10) arranged in at least one row, and in which each tube (10) has a body (12) terminated by an end portion (14) which is received in a header plate (20; 46; 94), characterised in that at least two adjacent tubes (10) of the bundle define a terminal pitch distance (A'; B') which separates their respective end portions and which is different from a central pitch distance (A; B) separating their respective bodies.
2. A heat exchanger according to Claim 1, characterised in that the terminal pitch distance (A') of the two adjacent tubes (10) is greater than their central pitch distance (A).
3. A heat exchanger according to Claim 2, characterised in that the two adjacent tubes (10) defining the terminal pitch distance (A') and central pitch distance (A) are in two different rows of the bundle.
4. A heat exchanger according to Claim 2 or Claim 3, characterised in that the respective end portions (14) of the two tubes (10) of the bundle are each received individually in a hole (24) in the header plate (20), with the latter having a plurality of rows of holes (24) which are arranged in such a way that the pitch distance separating two adjacent holes in two different rows corresponds to the terminal pitch distance (A') of the tubes.
5. A heat exchanger according to Claim 1, characterised in that the terminal pitch distance (A'; B') of the two adjacent tubes (10) is smaller than their central pitch distance (A; B).
6. A heat exchanger according to Claim 5, characterised in that the two adjacent tubes (10) defining the terminal pitch distance (A') and central pitch distance (A) are in two different rows of the bundle.
7. A heat exchanger according to Claim 6, characterised in that the tubes of the bundle are grouped in pairs of adjacent tubes, and in that the respective end portions of the two adjacent tubes in a common pair are received in a common hole (50) in the header plate (46), the latter having the same number of holes as there are pairs of tubes.
8. A heat exchanger according to Claim 5, characterised in that the two adjacent tubes defining the terminal pitch distance (B') and central pitch distance (B) are part of the same row in the bundle.
9. A heat exchanger according to Claim 8, characterised in that the tubes (10) in the bundle are grouped in pairs of adjacent tubes, and in that the respective end portions (14) of the two tubes in a common pair are received in a common hole (90) in the header plate (94), the latter having the same number of holes as there are pairs of tubes.
10. A heat exchanger according to one of Claims 1 to 9, characterised in that the bodies (12) of the tubes (10) in the bundle have a generally oblong transverse cross section, while their end portions (14) have a less oblong transverse cross section, which may even be circular.

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