EP0952418B1 - Multifunctional heat exchanger, particularly for motor vehicle - Google Patents

Description

The invention relates to a multi-function type heat exchanger, or even multifluid, particularly suitable motor vehicles.

It relates more particularly to a heat exchanger comprising a single bundle of tubes and fins, divided in at least two parts suitable for being traversed by different fluids, which are intended to be cooled by a common cooling medium sweeping the beam, and in which the ends of the tubes are received in manifold plates connected to manifold boxes.

We already know, in particular from DE 195 09 654, a heat exchanger of this type in which the ends bundle tubes are received, on one side in a plate manifold connected to two manifolds and, on one side opposite, in another collector plate connected to two other manifolds.

This known heat exchanger comprises a single bundle of tubes which is divided into two parts traversed respectively by two different fluids. To each part of the beam corresponds to an inlet manifold and a outlet manifold for fluid circulation at cool.

In the embodiment described in the document above, the two fluids are constituted respectively by a supply air flow and by a fuel flow which must be cooled by the same air flow which sweeps the beam.

This known heat exchanger cannot operate in a safe way that in case the two fluids to cool have near temperatures.

On the other hand, if the two fluids were to have temperatures very different, the tubes of the first part of the beam and tubes of the second part of the beam present different dilations of a nature to generate stresses at the ends of the tubes.

As these ends are received each time in the same manifold, these constraints could cause deformation, or even a rupture of this manifold.

This known heat exchanger cannot therefore be used when the two fluids to be cooled have temperatures very different, as is the case when one of the parts of the beam constitutes a cooling radiator of a heat engine and another part of the beam constitutes a cooling radiator, also called "cooler", engine charge air.

Indeed, the supercharging of a heat engine consists to supply it with compressed air and not directly atmospheric air, so as to increase the mass of oxygen available in combustion chambers. The compression of the air is accompanied by a sharp rise in temperature, which can reach values of 150 ° C, or more.

These values are much higher than those of the engine cooling ranging from ambient to engine start up to a range of about 80 to 100 ° C in normal diet.

FR 2 712 674 shows an exchanger traversed by two distinct fluids.

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

It aims in particular to provide a heat exchanger multifunctional likely to be traversed by fluids different, possibly at very different temperatures, and this without risk of damage to the beam due to differential expansion phenomena.

It aims in particular to provide a heat exchanger of this type which can be used to ensure both the motor vehicle engine cooling and the cooling of the charge air of said engine.

To this end, the invention provides a heat exchanger of the type defined in the introduction in which, at each end of the bundle, the ends of the tubes are connected to at least two separate collector plates, one separated from the other by a beam tube, called "inactive tube", and in which the two collector plates are assembled respectively to separate manifolds suitable for being crossed respectively by the fluids.

Thus, the heat exchanger of the invention comprises a single bundle of tubes and fins, but this bundle is divided into two parts so that the ends of the tubes belonging respectively to the two parties are received in two separate header plates, not in one single collecting plate as in the prior art.

These two separate collector plates are each time separated from each other by a tube of the beam, which one calls "tube inactive" because this tube is not traversed by any fluid and simply acts as a thermal barrier between the collector plates.

As a result, even if the two parts of the beam are traversed by fluids at very distant temperatures each other, there is no risk of deterioration occur from the fact that both sides have plates totally separate manifolds and manifolds.

In a preferred embodiment of the invention, the bundle is formed by an alternating stack of flat tubes and fins produced in the form of dividers wavy.

The aforementioned flat tubes are advantageously of the multi-channel type.

Collector plates and manifolds can be assembled together, either mechanically with interposition a seal, or again by brazing.

The invention applies very particularly to the case where the beam includes two parts suitable for being swept by a same flow of cooling air. Of course, this beam could include more than two parts, still swept by the same cooling air flow.

In a preferred application of the invention, a part of the beam constitutes a cooling radiator of a heat engine, and another part of the beam constitutes a radiator for cooling the air of supercharging of said engine.

In the following description, made only as example, reference is made to the accompanying drawing, in which the single figure represents a partial perspective view, with bursting, of a heat exchanger according to the invention.

The heat exchanger shown in the accompanying drawing includes a single beam 1 formed by an alternating stack flat tubes 2 and fins 3 formed by spacers wavy.

The tubes 2 are so-called "two-channel" tubes obtained by bending and brazing of a metal sheet, in particular at aluminum base. Each of the tubes internally defines two parallel channels 4 for the circulation of a fluid.

The fins 3 are usually formed from the same material metallic and these are connected by brazing to tubes 2.

The bundle tubes are identical to each other and are divided into a first series of tubes 2a intended to be traversed by a first fluid F1 and in a second series tubes 2b intended to be traversed by a second fluid F2.

In the example, the first fluid F1 consists of the coolant (usually water added antifreeze) of a heat engine, in particular of motor vehicle. The second fluid F2 consists of charge air from said heat engine.

It is recalled here that the supercharging of an engine thermal consists in supplying it with compressed air and not directly into atmospheric air, so as to increase the mass of oxygen available in the combustion chambers. The compression of the air is accompanied by a strong rise in temperature and it is therefore necessary to cool this air.

The fins define free spaces between the tubes for the circulation of a cooling air flow F3 which is common to all tubes in the bundle.

The bundle 10 comprises a particular tube 2i, called "tube inactive ", which separates tubes 2a from tubes 2b. This tube inactive 2i constitutes a thermal barrier which separates a first part P1 of the bundle consisting of tubes 2a and associated fins and a second part P2 of the beam consisting of tubes 2b and associated fins.

Indeed, the fluid F1 and the fluid F2 can have very different temperatures, likely to cause constraints in the beam. For example, the temperature F1 fluid (coolant) can vary from the ambient value up to about 100 ° C, while the fluid F2 (charge air) can reach temperatures of the order of 150 ° C or more, which leads to differential expansion phenomena between tubes 2a and the tubes 2b.

The tubes 2a have ends 5a, also called "feet of tubes ", received in openings of a collector plate 6, also called "collector", which is assembled in a box collector 7. The assembly constituted by the collector plate 6 and the manifold 7 defines a volume serving as inlet (or outlet) compartment for fluid F1.

The collector plate 6 has a peripheral edge 8 delimiting a gutter in which is received a ledge device 9 of the manifold 7, with interposition a seal 10. The edge 8 of the collector plate 6 is crenellated and folded against the rim 9 of the box manifold 16 to form folded legs 11.

The tubes 2b have respective ends 5b received in openings of another manifold plate 12 which is separate from the collector plate 6 and separated from this last through the inactive tube 2i.

Similarly, the collector plate 12 is assembled to another manifold 13. The manifold 12 includes a peripheral edge 14 delimiting a peripheral gutter in which is received a peripheral edge 15 of the box manifold 13 with interposition of a seal 16.

The collecting plate 12 and the collecting box 13 define together a volume serving as an entry compartment (or outlet) for fluid F2.

As a result, the assembly formed by the collector plate 6 and the manifold 7, on the one hand, and the assembly formed by the collecting plate 12 and the collecting box 13, on the other hand, are completely separate, although they are connect to the same bundle of tubes.

Consequently, if the tubes 2a and the tubes 2b are traversed by fluids having very different temperatures, and therefore subject to differential expansion phenomena important, this does not entail any constraints in terms of manifolds and manifolds.

Thus, the invention makes it possible to overcome these phenomena differential expansion while retaining the advantage to use a single bundle made up of all identical tubes. Since the exchanger includes boxes different collectors, it is possible to train these last from different materials. For example, the manifold 7 can be made of plastic and the manifold 13 in metallic material.

The figure in the drawing shows only one end of the beam. The latter has an opposite end which is equipped with two other similar collector plates and also two other similar manifolds.

Of course, the invention is not limited to the form of embodiment described previously by way of example.

Thus, it will be understood that the assembly between a plate manifold and a manifold can be made no only mechanically, i.e. with interposition a seal as described above, but also by soldering.

In addition, the heat exchanger of the invention may include more than two parts so as to be crossed by more of two different fluids. In such a case, provision should be made at least two inactive tubes separating at least three series different from bundle tubes.

Also, the invention is not limited to the particular case a heat exchanger comprising a part forming engine cooling radiator and a other part forming charge air cooler of this engine.

Claims (7)

1. Heat exchanger comprising a single bundle (1) of tubes (2a, 2b, 2i) and fins (3) split into at least two parts (P1, P2) separated by a tube (2i) of the bundle, known as the "inactive tube", and which can have flowing through them different fluids (F1, F2) which are intended to be cooled by a common cooling medium (F3) sweeping across the bundle, and in which the ends of the tubes are housed in manifold plates connected to manifold boxes,
   characterized in that, at each end of the bundle (1), the ends (5a, 5b) of the tubes (2a, 2b) are connected to at least two distinct manifold plates (6, 12) which are separated from one another by the inactive tube (2i) of the bundle, in that the inactive tube (2i) of the bundle is identical to the other tubes (2a, 2b) of the bundle, and in that the two manifold plates (6, 12) are assembled each to distinct manifold boxes (7, 13) through which the respective fluids (F1, F2) can pass.
2. Heat exchanger according to Claim 1, characterized in that the bundle (1) is formed of an alternating stack of flat tubes (2a, 2b, 2i) and of fins (3) which fins are produced in the form of corrugated inserts.
3. Heat exchanger according to Claim 2, characterized in that the flat tubes (2a, 2b, 2i) are multi-bore.
4. Heat exchanger according to one of Claims 1 to 3, characterized in that the manifold plates (6, 12) and the manifold boxes (7, 13) are mechanically assembled with the insertion of a seal (10, 16).
5. Heat exchanger according to one of Claims 1 to 3, characterized in that the manifold plates (6, 12) and the manifold boxes (7, 13) are assembled by brazing.
6. Heat exchanger according to one of Claims 1 to 5, characterized in that the bundle (1) comprises two parts (P1, P2) which can be swept by one and the same stream of cooling air (F3).
7. Heat exchanger according to one of Claims 1 to 6, characterized in that part (P1) of the bundle (1) constitutes a combustion engine cooling radiator and in that another part (P2) of the bundle (1) constitutes an intercooler for cooling the engine supercharging air.

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