FR3067098B1 - VENTILATION DEVICE FOR GENERATING AN AIR FLOW THROUGH A HEAT EXCHANGER IN A MOTOR VEHICLE - Google Patents

Abstract

The present invention relates to a ventilation device (2) for generating an air flow (F1) through a heat exchanger (1) of a motor vehicle, the ventilation device (2) comprising a plurality of ducts (7) comprising each at least one air passage opening (16) of an air flow (F) passing through the corresponding conduit (7), the air passage opening being configured to eject the air flow substantially in the direction of the heat exchanger (2), a supply circuit (12) of the airflow ducts (7) to be directed to the heat exchanger (2), and at least one misting device (24) configured to generate droplets of a liquid in said airflow (F).

Description

VENTILATION DEVICE FOR GENERATING AN AIR FLOW THROUGH A VEHICLE HEAT EXCHANGER

AUTOMOBILE

The present invention relates to the field of ventilation devices, and more particularly to the field of ventilation devices for a motor vehicle cooling module.

Motor vehicles, whether combustion or electric, need to evacuate the calories generated by their operation and are therefore equipped with heat exchangers. A motor vehicle heat exchanger generally comprises tubes, in which a heat transfer fluid is intended to circulate, in particular a liquid such as water, and heat exchange elements connected to these tubes, often referred to as " fins "or" spacers ". The fins or spacers make it possible to increase the exchange surface between the tubes and the ambient air.

However, in order to further increase the heat exchange between the coolant and the ambient air, it is frequent that a ventilation device is used in addition, to generate or increase a flow of air directed to the tubes and the fins / spacers.

Such a ventilation device most often comprises a propeller fan, which has several disadvantages. First, the assembly formed by the propeller fan and its motorization system occupies a large volume. In addition, the distribution of the air vented by the propeller, often placed in the center of the row of tubes, is not homogeneous over the entire surface of the heat exchanger. In particular, some regions of the heat exchanger, such as the ends of the heat pipes and the corners of the heat exchanger, are not or only slightly reached by the air flow ejected by the propeller. Finally, when the start of the ventilation device is not necessary, especially when the heat exchange with the ambient air is sufficient to cool the coolant, the blades of the propeller and the nozzle that supports the propeller partially obstruct or "mask" the flow of ambient air to the tubes and fins. This limits the exchange of heat between the ambient air, on the one hand, and the tubes and fins, on the other hand.

An object of the invention is to provide a ventilation device for heat exchanger not having at least some of the disadvantages of known heat exchanger ventilation devices. For this purpose, the subject of the invention is a ventilation device intended to generate an air flow through a motor vehicle heat exchanger, the ventilation device comprising: a plurality of ducts each comprising at least one opening of passing an air flow through the corresponding duct, the air passage opening being configured to eject the airflow substantially in the direction of the heat exchanger, - a duct supply circuit in airflow, and - at least one misting device configured to generate droplets of a liquid in said air flow.

Thus, advantageously, the plurality of ducts from which air is ejected advantageously makes it possible to replace the conventional propeller arranged in front of the heat transfer fluid circulation tubes of the heat exchanger, without presenting the disadvantages mentioned above. .

Indeed, with equal heat exchange capacity, the volume occupied by such a ventilation device is much less than a propeller ventilation device. In addition, the distribution of air vented by the tubes is easier to control and can be made more homogeneous. Also, thanks to the device according to the invention, it limits the obstruction of the flow of air to the heat exchanger. Indeed, the ducts of the ventilation device can advantageously be arranged opposite areas of low heat exchange of the heat exchanger, called "dead zones", such as the end faces of the tubes through which the coolant, which does not are not in contact with cooling fins / inserts. This is not possible with a conventional propeller.

Furthermore, the invention makes it possible to deport the air propulsion means supplying air flow to the ducts of the ventilation device, at a distance from the row of heat transfer fluid circulation tubes, which offers greater freedom in the design of the heat exchanger.

The ducts of the ventilation device arranged in a row, have a higher mechanical strength than a propeller.

Finally, by generating liquid droplets in the airflow, misting is created in the airflow, lowering the temperature of the airflow upstream of the heat exchanger. Thus, the cooling of the heat exchanger is further improved.

Preferably, the ventilation device for a motor vehicle heat exchanger according to the invention comprises one or more of the following characteristics, taken alone or in combination: each opening is delimited by a pair of guide lips projecting from a wall of the corresponding conduit, each pair of guide lips being preferably configured to guide the flow of air, ejected through the opening, in a direction substantially perpendicular to a direction of elongation of the corresponding tube; - The guide lips are substantially planar and / or substantially parallel, the guide lips preferably extending mainly in a longitudinal direction of the tubes and a direction perpendicular to this longitudinal direction; each duct has a section comprising: a leading edge; a trailing edge opposite the leading edge and intended to be arranged opposite the heat exchanger; a first and a second profile; extending each between the leading edge and the trailing edge, said at least one opening of the conduit being on one of the first and second profiles, said at least one aperture preferably being in the vicinity of the leading edge said at least one opening being more preferably configured so that the flow of air passing through the conduit and ejected by said at least one opening flows along at least a portion of said one of the first and second profiles ; the device comprises at least one pair of tubes, the tubes of the pair of tubes being arranged so that their respective openings are facing one another / from each other; the tubes comprise at least one opening in the first profile and at least one opening in the second profile; the first profile and the second profile are symmetrical with respect to a plane passing through the leading edge and the trailing edge of the tube; the trailing edge is delimited by first and second converging walls; at least one tube comprises means for guiding the flow of air flowing in a passage section of the tube towards said at least one opening, the guide means preferably being deflectors, the deflectors being, preferably, coming from material with said at least one tube; the air flow supply circuit of the ducts comprises at least one air intake manifold, preferably two air intake manifolds, the ducts being connected to said manifold (s) ( s) air intake, including their ends; - The tube air flow supply circuit comprises a turbomachine, including a fan; the ducts are substantially rectilinear, parallel to each other and aligned so as to form a row of ducts; the misting device (s) open: in the vicinity of the orifice (s), in particular upstream or downstream of the orifice (s) relative to the direction of flow of the air flow; and / or in the intake manifold or manifolds, especially in the vicinity of duct inlets from the intake manifold or manifolds; and / or - in the ducts, in the vicinity of the openings and / or in a passage section of the flow of air in the ducts; - The misting device comprises one or more droplet generators and a hydraulic liquid supply circuit of the droplet generator (s); the hydraulic circuit comprises at least one portion extending in the plurality of ducts and / or in the air intake manifold or manifolds; or the hydraulic circuit is devoid of any portion extending in the plurality of ducts and / or in the intake manifold or manifolds; and the droplet generator or generators comprise at least one of: one or more high pressure nozzles; - one or nozzles at low pressures; - one or more impact nozzles; and / or - one or more ultrasonic nebulizers.

According to another aspect, the invention relates to a cooling module for a motor vehicle comprising a heat exchanger and a ventilation device as described above in all its combinations, the ventilation device being adapted to direct the flow of heat. air towards the heat exchanger. The invention will be better understood, and other objects, details, characteristics and advantages thereof will appear more clearly on reading the following explanatory description which will follow purely illustrative and non-limiting examples, with reference to the schematic drawings. attached. In these drawings: FIG. 1 is a perspective view of an example of a cooling module comprising a heat exchanger and a ventilation device; Figure 2 is a view similar to Figure 1, cut along the plane 11-11; Figure 3 is a perspective view of ventilation ducts of the ventilation device of Figure 1; Figures 4 to 6 illustrate, in broken view, variants of the ventilation device of Figure 1; Figures 7 to 9 illustrate schematically in cross section, ventilation ducts can be implemented in variants of the ventilation device of Figure 1; Figure 10 is a sectional view of a second example of a cooling module comprising a heat exchanger and a ventilation device; Figure 11 is a schematic sectional view of a ventilation duct implemented in the cooling module of Figure 10; Figure 12 is a view similar to Figure 11, illustrating alternative positioning of misting devices in the ventilation duct; Figures 13 and 14 are views similar to Figure 11, the cross section of other examples of ventilation ducts that can be implemented in a ventilation device; FIG. 15 is a perspective view of a cooling module with a ventilation device provided with ventilation ducts according to FIG. 14; and Figure 16 is a perspective view of a variant ventilation duct, integral with a heat transfer fluid circulation tube, which can be implemented in a cooling module.

In the remainder of the description, the elements that are identical or of identical function bear the same reference sign. For brevity of the present description, these elements are not described in detail in each embodiment. On the contrary, only the differences between the variant embodiments are described in detail.

FIG. 1 shows a first example of a cooling module 10 (or heat exchange module) intended to equip a motor vehicle for cooling an engine of the motor vehicle and / or its equipment. The cooling module 10 comprises a heat exchanger 1 and a ventilation device 2. The heat exchanger 1 comprises tubes 4 for circulating coolant (for example water, coolant or refrigerant) substantially rectilinear and extending in a longitudinal direction, parallel to each other and aligned so as to form a row of heat transfer fluid circulation tubes 4.

More particularly, each heat transfer fluid circulation tube 4 has a substantially oblong cross section, and is delimited by first and second plane walls 4a, 4b, which are connected to fins or heat exchange tabs. For reasons of clarity, the fins are not shown in Figures 1 and 2.

Conventionally, the heat transfer fluid circulation tubes 4 are connected on the one hand to a heat transfer fluid intake manifold 5 at a first end and, on the other hand, to a fluid evacuation manifold 6 coolant, at a second end, in order to circulate the heat transfer fluid in the tubes 4.

Moreover, the ventilation device 2 comprises a plurality of ducts 7, which in the same way as the heat transfer fluid circulation tubes 4, can be substantially straight, parallel to each other and aligned so as to form a row of tubes 7. In the following, the ducts 7 of the ventilation device 2 are called "ventilation tubes", as opposed to the tubes 4 of the heat exchanger 1, which they are called "heat transfer", because they allow the circulation of the coolant.

Preferably, and as can be seen in Figures 1 and 2, the heat pipes 4 and the ventilation tubes 7, are all parallel to each other. Thus, the rows of ventilation tubes 7 and heat-transfer tubes 4 are parallel. In addition, the ventilation tubes 7 are arranged so that each of them is opposite a heat-transfer tube 4.

The number of ventilation tubes 7 is adapted to the number of heat-transfer tubes 4. For example, for a conventional heat exchanger 1, the ventilation device 2 may comprise, for example, between eight and forty ventilation tubes 7, preferably between fifteen and thirty-six ventilation tubes 7 for a heat exchanger comprising between forty and seventy heat-transfer tubes 4.

Preferably, the front surface of the ventilation tubes 7 is less than 85% of the front surface occupied by the heat-transfer tubes 4. The frontal surface refers to the surface oriented substantially normal to the direction of a flow of heat. outside air passing through the ventilation device 2 and the heat exchanger 1, in operation of the motor vehicle.

Moreover, in order to limit the volume of the cooling module 10, while obtaining heat exchange performance similar to that of a propeller ventilation device, the row of ventilation tubes 7 is preferably arranged at a distance between 0 and 100 mm with respect to the row of heat-transfer tubes 4, more preferably at a distance of 0 mm, that is to say that the ventilation tubes 7 are then juxtaposed with the heat-transfer tubes 4 and substantially in contact with each other. of these, or at a distance greater than 10 mm and / or less than 50 mm.

Similarly, again to limit the volume occupied by the cooling module 10, the height of the row of ventilation tubes 7 (here the height here being the dimension corresponding to the direction in which the ventilation tubes 7 are aligned) is Preferably, for example, the height of the row of heat transfer tubes 4 being 431 mm, the height of the row of ventilation tubes 7 is substantially equal to or less than the height of the heat pipe row 4. at this value.

The ventilation device 2 further comprises a device for propelling a flow of air L, not visible in FIGS. 1 and 2. This device for propelling an air flow supplies the ventilation tubes 7 via a circuit the air supply circuit, as shown in Figures 1 and 2, comprises in particular two air intake manifolds 12 to which are connected the tubes of ventilation 7 via air supply inlets 14 located at each of their ends. The supply circuit may comprise, in addition to the air intake manifolds 12, the air propulsion device and / or ducts connecting or intended to connect the air propulsion device to the intake manifolds of the air intake device. air 12. The air propulsion device, for example one or more turbomachines, thus propels air through the intake manifolds 12, to the ventilation tubes 7. The air propulsion device can thus be remote, away from ventilation tubes 7.

The ventilation tubes 7 comprise, as is more particularly visible in FIG. 3, an opening 16 intended to be arranged opposite the heat exchanger 1, and preferably so that the opening 16 of each tube of ventilation 7 is vis-à-vis a heat-transfer tube 4, as can be seen in Figures 1 and 2. Furthermore, the ventilation tubes 7 are configured so that the flow of air F flowing in the ventilation tubes 7, through a passage section of the ventilation tubes 7, is ejected through the opening 16. Thus, the openings 16 being arranged opposite the heat exchanger 1, the air flow F is ejected in the direction of the heat-transfer tubes 4 and / or the cooling fins arranged between the heat-transfer tubes 4.

As seen more particularly in Figure 3, except at their air intake inlet ends 14, which have a substantially circular cross section, the ventilation tubes 7 have a substantially oblong cross section, forming a passage section for the air flow F in the ventilation tubes 7. This substantially oblong cross section is interrupted by the opening 16. This form of the ventilation tubes 7 simplifies the manufacture of these ventilation tubes 7 and gives a good mechanical strength to the ventilation tubes 7. Ventilation tubes of this shape may for example be made by folding an aluminum foil, or by three-dimensional printing, in particular of a metallic material or a plastic material, but also by molding or overmolding.

To increase the flow of air F ejected to the heat exchanger 1, and as can be seen in Figure 3 in particular, the openings 16 consist of slots in the wall 17 of the ventilation tubes 7, s' extending in the direction of elongation of the ventilation tubes 7. This slot form allows to form a large air passage in the direction of the heat exchanger 1 without greatly reducing the mechanical strength of the ventilation tubes 7. Thus in order to obtain the largest possible air passage, the openings 16 extend over a large part of the length of the ventilation tubes 7, preferably at least 90% of this length.

In this case, given the orientation of the heat-transfer tubes 4, the ventilation tubes 7 and the openings 16, the air flow F is ejected substantially perpendicular to the direction of elongation of the ventilation tubes 7. and more particularly perpendicularly to the longitudinal direction of the ventilation tubes 7.

Each opening 16 may be delimited by guide lips 18 protruding from the wall 17 of the ventilation tube 7. Because they protrude from the wall 17 of each ventilation tube 7, the guide lips 18 make it possible to guide the air ejected through the opening 16 from the inside of the ventilation tube 7 towards the heat exchanger 1.

More particularly, the guide lips 18 may be configured to guide the flow of air ejected through the opening 16 so that it flows in a direction substantially perpendicular to the direction of elongation of the ventilation tubes 7 .

The guide lips 18 are preferably flat and substantially parallel. For example, the guide lips 18 are spaced from each other by a distance of about 5 mm and / or have a width, measured perpendicular to the elongation direction of the ventilation tubes 7, greater than 2 mm and / or less than 5 mm. The guide lips 18 extend preferably all along each opening 16, in the longitudinal direction of the ventilation tubes 7.

The guide lips 18 are preferably integral with a ventilation tube 7. The guide lips 18 are for example made by folding the wall 17 of the latter.

In order to facilitate the guiding of the air flow L coming from the supply inlets 14, which initially circulates in the direction of elongation of the ventilation tubes 7, towards the openings 16, at least one of the ventilation tubes 7 comprises means for guiding the flow of air flowing towards the opening 16. Such guiding means make it possible to facilitate the "turning" of the flow of air coming from the intake inlets 14 towards the opening 16 made in the wall 17 of the tube Preferably, all ventilation tubes 18 comprise such airflow guiding means 20. The guide means may in particular take the form of reliefs or deflectors, in particular integral with the ventilation tube 7 or reported in this ventilation tube 7.

The guide means 20 comprise, in the example of Figures 1 to 3, a plurality of deflectors 22. In this case, the deflectors 22 are integral with the ventilation tube 7. These deflectors 22 are preferably arranged regularly The deflectors 22 are preferably arranged close to the opening 16. More particularly, the deflectors 22 extend between the guide lips 18. More particularly, the deflectors 22 extend in the vicinity of the opening. a plane substantially normal to the direction of elongation of the aerodynamic tube 7 to guide the air in a direction perpendicular to the direction of elongation of the ventilation tubes 7.

Moreover, as can be seen in FIG. 4, the ventilation device 2 comprises a misting device 24 comprising here droplet generators 26, hereinafter referred to as misting devices 26, and a hydraulic circuit 28 for supplying liquid to the atomizers. 26. The hydraulic circuit 28 may comprise a source of liquid, not shown in Figure 4. Alternatively, the hydraulic circuit 28 consists of a set of conduits for connecting the foggers to the liquid source. A pump may be provided to circulate the liquid in the hydraulic circuit 28. The liquid source may be offset relative to the ventilation device 2. The liquid is for example water. In FIG. 4, the foggers 26 mist the water (ie generate water droplets) in the air stream L inside the air intake manifolds 12. This fogging makes it possible to lower the temperature of the air flow L, upstream of the heat exchanger 1, and thus to further improve the cooling capacity of the heat exchanger 1 by means of the ventilation device 2.

The droplets thus formed by misting have for example a diameter of between 1 and 1000 microns.

In practice, two variants of the misting device 24 are shown in FIG. 4: in the air intake manifold 12G, on the left in this FIG. 4, the misting device 24 comprises a plurality of misting devices 26 and a hydraulic circuit 28, extending over substantially the entire height of the air intake manifold 12G. There are preferably as many foggers 26 as ventilation tubes 7 in the ventilation device 2. In this case, the foggers 26 are preferably arranged vis-à-vis the ventilation tubes 7. The foggers 26 are preferably oriented towards the air intake inlets 14 of the ventilation tubes 7 so as to be able to spray the water directly into the ventilation tubes 7. The liquid supply of the hydraulic circuit 28 is made from one end, in particular a lower end, 12G air intake manifold; in the air intake manifold 12D, on the right in this figure 4, the misting device 24 comprises a single fogger 26, located in the air intake manifold 12D. Here, fogging tunic 26 is disposed at a longitudinal end of the air intake manifold 12D, here the lower end of the air intake manifold 12D. According to a variant not shown, fogging tunic is disposed at the upper end of the air intake manifold 12D. In both cases, the misting tunic is preferably adapted to mist water upstream, in the direction of flow of air F, of all the air intake inlets 14 of the ventilation tubes 7 or, at the very least, air intake inlets 14 of at least a portion of the ventilation tubes 7.

FIG. 5 illustrates two other variants of the misting device 24, substantially identical to the variants of FIG. 4. The main difference is that, in FIG. 5, the liquid supply of the hydraulic circuit 28 is substantially from the side the air intake manifold 12D, 12G, in particular substantially from the middle of this intake manifold 12D, 12G. In addition, according to the example shown in the collector 12D, right in this figure 5, the mist 26 is disposed substantially in the middle of the collector 12D. The fogger 26 is advantageously oriented substantially in the direction of the air flow F at the inlet into the air intake manifold 12D. Indeed, in this case, the mist water is advantageously driven by the air flow F to the openings 16 of the different ventilation tubes 7.

The configurations of the devices of FIG. 4 (left) and 5 require that a part of the hydraulic circuit 28 and / or the foggers 26 extend into the air passage in the intake manifold 12, provided for the passage of the On the other hand, FIG. 6 shows two variants of the misting device 24, in which the hydraulic circuit 28 extends outside the air intake manifold 12G, 12D. On the other hand, the foggers 26, in this case nozzles, are fixed on the air intake manifolds 12G, 12D so as to be able to spray water inside the air intake manifold 12G , 12D. In this FIG. 6 again, the configuration of the left part comprises as many foggers 26 as there are ventilation tubes 7, whereas the configuration on the right comprises a single fogger 26, located upstream, relative to the direction of the air flow F, of all the ventilation tubes 7. These variants make it possible to less disturb the air flow F in the intake manifolds 12G, 12D.

It is understood that in practice, the intake air manifold 12D, on the right, and the air intake manifold 12G, on the left, can be equipped with the same type of misting device 24. FIGS. 6 have variants on their left and right, to limit the number of figures to present.

Alternatively, also, the misting device 24 may comprise a hydraulic circuit 28 extending in part inside or outside the ventilation tubes 7, into the ventilation tubes 7 where the fogger 26 are arranged. FIGS. 7 to 9 thus illustrate variants of the cross-section of the ventilation tubes 7, ventilation tubes 7 in which a portion of the hydraulic circuit 28 and the foggers 26 are each installed. In this case, preferably, the Misting 24 comprises several foggers 26 by ventilation tube 7. In particular, each fogger 26 may be arranged between two successive deflectors 22 or between the intake inlet 14 and the deflector 22 closest to the intake inlet 14. More preferably, each fogger 26 is oriented substantially in the direction of the opening 16, in a direction perpendicular to the longitudinal direction of the ventilation tube 7 in which it is installed.

Advantageously, each air intake manifold 12G, 12D of FIGS. 4 to 6 is devoid of any other opening than: the orifices into which the ventilation tubes 7 open, mouths intended to be in fluid communication with a or several turbomachines for supplying air flow to the air intake manifold considered, and - passages necessary for the misting device to mist water in the air intake manifold considered.

In particular, each air intake manifold 12G, 12D preferably has no opening oriented towards the heat exchanger 1, which in this case would make it possible to eject a part of the flow of air flowing through the collector. of air 12G, 12D, directly towards the heat exchanger 1, without traversing at least a portion of a ventilation tube 7. Thus, all the air flow created by the turbine engine or turbomachines traversing the 12G collectors, 12D, is preferably distributed between substantially all the ventilation tubes 7. This allows a more homogeneous distribution of this air flow.

In FIG. 7, the ventilation tube 7 has a section of substantially elliptical shape whose small axis corresponds to the height h of the ventilation tubes 7 and the major axis to the width of the ventilation tubes 7. For example, the minor axis h of the ellipse has a length of about 11 mm.

In the examples of Figures 8 and 9, the cross section of the ventilation tubes 7 is substantially circular, interrupted by the opening 16. For example, the diameter of the circle interrupted by the opening 16 is about 11 mm.

In addition, the guide lips 18 extend partly inside the ventilation tubes 7. Preferably, the guide lips 18 extend inside the ventilation tubes 7 over half of their width. as shown in Figures 8 and 9. For example, the guide lips 18 having a width of 4 mm, the portion extending inside the ventilation tube 7 has a width of 2 mm.

In the example illustrated in FIG. 9, for each guide lip 18, an obstruction wall 30 connects the end 18e of the guide lip 18, inside the ventilation tubes 7, to the internal surface 32 of the wall 17 of the ventilation tube 7. This makes it possible to limit the phenomenon of recirculation of the air in the space between the guide lip 18 and the inner surface 32 of the wall 17 of the ventilation tube 7.

In the example illustrated in FIG. 9 again, the obstruction wall 30 is flat and extends perpendicularly to the guide lip 18. The volume V contained between the obstruction wall 30 and the wall 17 of the ventilation tube 7 can be full.

FIGS. 10 and 11 illustrate another example of ventilation tubes 7 called aerodynamic tubes 7 in the following.

An aerodynamic tube 7, as illustrated in FIG. 11 for example, has on at least one portion, preferably over substantially its entire length, a transverse section 48 comprising a leading edge 50, a trailing edge 52 opposite to the leading edge 50 and, here, disposed opposite the heat transfer tubes 4, and a first and a second profiles 54, 56, each extending between the leading edge 50 and the trailing edge 52. The edge of Attack 50 is for example defined as the point at the front of the section 48 of the aerodynamic tube 7 where the radius of curvature of the cross section 48 is minimal. The front of the cross section 48 of the aerodynamic tube 7 can be defined as the portion of the section 48 of the aerodynamic tube which is opposite-that is to say which is not in front of - Of the heat exchanger 1. Similarly, the trailing edge 52 may be defined as the point at the rear of the section 48 of the aerodynamic tube 7 where the radius of curvature of the section is minimal. The rear of the section 48 of the aerodynamic tube 7 can be defined for example as the portion of the section 48 of the aerodynamic tube 7 which is opposite the heat exchanger 1.

The distance c between the leading edge 50 and the trailing edge 52 is for example between 50 mm and 70 mm. This distance is here measured in a direction perpendicular to the alignment direction of the row of aerodynamic tubes 7 and to the longitudinal direction of the aerodynamic tubes 7.

In the example of Figure 11, the leading edge 50 is free. In this figure also, the leading edge 50 is defined on a parabolic portion of the cross section 48 of the aerodynamic tube 7.

The aerodynamic tube 7 illustrated in FIG. 11 also comprises at least one opening 16 for ejecting a stream of air passing through the aerodynamic tube 7, outside the aerodynamic tube 7 and the air intake manifold 12, in particular substantially in the direction of the heat exchanger 1. The opening or each opening 16 is for example a slot in an outer wall 17 of the aerodynamic tube 7, the slot or slots 16 extending for example in the direction of elongation of the tube aerodynamic 7 in which they are made. The total length of the opening 16 or the openings may be greater than 90% of the length of the aerodynamic tube 7. Each opening 16 is distinct from the ends of the aerodynamic tube 7, through which the aerodynamic tube 7 opens into an air collector 12. Each opening 16 is also outside the air collector 12. The slit shape makes it possible to form a large air passage 58 in the direction of the heat exchanger 1 without greatly reducing the mechanical strength aerodynamic tubes 7.

In the following only describes an opening 16 being understood that each opening 16 of the aerodynamic tube 7 may be identical to the opening 16 described. The opening 16 is for example disposed near the leading edge 50. In the example of Figure 11, the opening 16 is on the first profile 54. In this example, the second profile 56 is devoid of opening 16. The opening 16 in the first profile 54 is configured so that the flow of air ejected through the opening 16 flows along at least a portion of the first profile 54.

As illustrated in FIG. 10, the aerodynamic tubes 7 of the ventilation device 2 can be alternately oriented with the first profile 54 or the second profile 56 facing upwards of this FIG. 10. Thus, alternatively, two neighboring aerodynamic tubes 7 are such that their first profiles 54 are vis-à-vis or, conversely, their second profiles 56 are vis-à-vis. The distance between two aerodynamic tubes 7 neighbors whose second profiles 56 are vis-à-vis may be less than the distance between two aerodynamic tubes 7 neighbors whose first profiles 54 are vis-à-vis. The distance between the center of the geometrical section of a first aerodynamic tube 7 and the center of the geometrical section of a second aerodynamic tube 7, such that the first profile 54 of the first aerodynamic tube 7 is opposite the first profile 54 of the second aerodynamic tube 7, measured in the alignment direction of the aerodynamic tubes 7 is for example greater than or equal to 15 mm, preferably greater than or equal to 20 mm, and / or less than or equal to 30 mm, preferably less than or equal to 25 mm.

For each pair of aerodynamic tubes 7 whose openings 16 are in facing relation, the air flows F ejected by these openings 16 thus create an air passage 58 in which a part, called induced air I, of the ambient air A is driven by suction. It should be noted here that the flow of air ejected by the openings 16 runs along at least part of the first profile 54 of the aerodynamic tube 7, for example by Coanda effect, as illustrated for example in FIG. 10. Taking advantage of this phenomenon it is possible, thanks to the entrainment of the ambient air A in the created air passage 58, to obtain a flow of air sent to the heat-transfer tubes 4 identical to that generated by a propeller fan while consuming less energy.

Indeed, the flow of air sent to the row of heat transfer tubes 4 is the sum of the air flow F ejected by the slots 16 and the induced air I. Thus, it is possible to implement a turbomachine of reduced power compared to a conventional fan propeller, generally implemented in the context of such a heat exchange module.

A first profile 54 having a Coanda surface also makes it possible not to have to orient the openings 16 directly towards the heat-transfer tubes 4, and thus to limit the size of the aerodynamic tubes 7. It is thus possible to maintain a passage section more important between the aerodynamic tubes 7, which promotes the formation of a greater induced air flow. The opening 16 is, in Figure 11, delimited by lips 18a, 18b. The distance e between the lips 18a, 18b, which defines the height of the opening 16, may for example be greater than or equal to 0.3 mm, preferably greater than or equal to 0.5 mm, more preferably greater than or equal to 0.7 mm and / or less than 2 mm, preferably less than or equal to 1.5 mm, more preferably less than 0.9 mm, more preferably less than or equal to 0.7 mm. The height of the slot is the size of this slot in the direction perpendicular to its length.

The lower the height of the slot 16, the greater the speed of the air flow ejected by this slot. A high speed of ejected airflow results in a high dynamic pressure. This dynamic pressure is then converted into static pressure in the mixing zone of the air flow ejected by the slot 16 and the induced air flow. This static pressure makes it possible to overcome the pressure losses due to the presence of the heat exchanger downstream of the ventilation device, in order to ensure a suitable flow of air through the heat exchanger. These pressure losses due to the heat exchanger vary in particular as a function of the heat pipe pitch and the pitch of the fins of the heat exchanger, as well as the number of heat exchangers that can be superimposed in the heat exchanger. heat exchange module. Indeed, the heat exchange module may comprise one or more heat exchangers of which one, several or all the exchangers can be cooled by the ventilation device. However, a slot height too low induces high pressure losses in the ventilation device, which involves using an air propulsion device or several oversized (s). This can lead to additional cost and / or create a space incompatible with the space available in the vicinity of the heat exchange module in the motor vehicle.

In particular, the heat exchanger 1 forming a resistance to the flow of air flowing therethrough, causing a pressure drop of said air flow, the height of the opening or openings 16 of the ventilation tubes 7 of the device ventilation 2 can be chosen according to said pressure drop caused by the heat exchanger 1.

The outer (or outer) lip 18a is constituted, as illustrated in FIG. 11, from the extension of the wall of the aerodynamic tube 7 defining the leading edge 50. The inner (or inner) lip 18b is constituted by a curved portion 62 of the first profile 54. An end 64 of the inner lip 18b may extend, as illustrated in FIG. 11, in the direction of the second profile 56, beyond a plane P normal to the free end of the outer lip 18a. In other words, the end 64 of the inner lip 18b can extend, in the direction of the leading edge 50, beyond the plane P normal to the free end of the outer lip 18a. The end 64 can then contribute to directing the flow of air flowing in the aerodynamic tube 7 towards the opening 16. The opening 16 of the aerodynamic tube 7 can be configured so that a flow of air flowing in this tube aerodynamic 7 is ejected by this opening 16, flowing along the first profile 54 substantially to the trailing edge 52 of the aerodynamic tube 7. The flow of air flow along the first profile 54 may result from the Coanda effect. It is recalled that the Coanda effect is an aerodynamic phenomenon that results in the fact that a fluid flowing along a surface at a short distance from it tends to outcrop or even hang on it.

To do this, here the maximum distance H between the first 54 and the second 56 profiles, measured according to an alignment direction of the aerodynamic tubes 7, is downstream of the opening 16. The maximum distance H can be greater than 10 mm, preferably greater than 11 mm and / or less than 20 mm, preferably less than 15 mm. Here, by way of example, the maximum distance H is substantially equal to 11.5 mm. A height H too low can cause significant pressure losses in the aerodynamic tube 7 which could require to implement a turbomachine more powerful and therefore more voluminous. For the same value of the distance between the aerodynamic tubes 7, measured according to the alignment direction of the aerodynamic tubes, or for the same pitch of the aerodynamic tubes 7, a too large height H limits the section of passage between the aerodynamic tubes for the aerodynamic tubes. induced air flow. The total air flow directed to the heat exchanger can then be reduced as well.

The first profile 54 comprises here a curved portion 62 whose apex 65 defines the point of the first profile 54 corresponding to the maximum distance H. The curved portion 62 may be arranged partly downstream of the opening 16 in the ejection direction of the air flow. In particular, a portion of the domed portion 62 may be contiguous with the inner lip 18b delimiting the opening 40.

Downstream of the convex portion 62 in the direction of ejection of said air flow through the opening 16, the first profile 54 of the aerodynamic tube 7 of the example of Figure 11 comprises a first portion 66 substantially straight. The second profile 56 comprises, in the example illustrated in FIG. 11, a substantially rectilinear portion 60, extending preferably over a majority of the length of the second profile 56. In the example of FIG. 11, the length L of the first rectilinear part 66, measured in a direction perpendicular to the longitudinal direction of the aerodynamic tube 7 and the alignment direction of the row of aerodynamic tubes, may be greater than or equal to 20 mm, preferably greater than or equal to 30 mm, and / or less than or equal to 60 mm. A relatively large length of this first rectilinear part is desired in particular for guiding the flow of air ejected from the opening 16. The length of this first rectilinear part is however limited because of the corresponding size of the ventilation device and its consequences on the packaging of the ventilation device or the heat exchange module.

In this case, the first rectilinear portion 66 of the first profile 54 and the straight portion 60 of the second profile 56 may form a non-flat angle Θ. The angle Θ thus formed may in particular be greater than or equal to 5 °, and / or less than or equal to 20 °, more preferably substantially equal to 10 °. This angle of the first rectilinear portion 66 with respect to the rectilinear part 60 of the second profile 56 makes it possible to accentuate the expansion of the total air flow. An angle Θ too great, however, may prevent the realization of the Coanda effect, so that the flow of air ejected through the opening 16 may not follow the first profile 54 and, therefore, not to be oriented correctly towards the heat exchanger 1.

The first profile 54 may further comprise, as illustrated in FIG. 11, a second rectilinear part 52a, downstream of the first straight part 66, in the direction of ejection of the air flow, the second rectilinear part 52a extending substantially parallel to the straight portion 60 of the second profile 56. The first profile 54 may also include a third straight portion 70, downstream of the second straight portion 52a of the first profile 54. The third rectilinear portion 70 may form a non-flat angle with the straight portion 60 of the second profile 56. The third rectilinear portion 70 may extend, as illustrated, substantially to a rounded edge connecting the third rectilinear portion 70 of the first profile 54 and to the straight portion 60 of the second profile 56. The rounded edge may define the trailing edge 52 of the cross section of the aerodynamic tube 7.

The straight portion 60 of the second profile 56 extends in the example of Figure 11 over the majority of the length c of the cross section. This length c is measured in a direction perpendicular to the longitudinal direction of the aerodynamic tubes 7 and to the alignment direction of the row of the aerodynamic tubes 7. This direction corresponds, in the example of FIG. 11, substantially to the direction of the flow of the induced air flow. In this embodiment, the length c of the cross section (or width of the aerodynamic tube 7) may be greater than or equal to 50 mm and / or less than or equal to 80 mm, preferably substantially equal to 60 mm. Indeed, the inventors have found that a relatively large length of the cross section of the aerodynamic tube makes it possible to more effectively guide the flow of air ejected through the opening 16 and the induced air flow, which mixes with this flow of air ejected. However, too great a length of the cross section of the aerodynamic tube 7 poses a problem of packaging of the ventilation device 2. In particular, the size of the heat exchange module can then be too large compared to the place that is available in the motor vehicle in which it is intended to be mounted. The packaging of the heat exchange module or the ventilation device can also be problematic in this case.

Moreover, as illustrated in FIG. 11, the second rectilinear portion 52a of the first profile 54 and the portion 52b of the rectilinear portion 60 of the second profile 56 that faces it are parallel. For example, the distance f between this second rectilinear part 52a and the portion 52b of the rectilinear portion 60 of the second profile 56 may be greater than or equal to 1 mm and / or less than or equal to 10 mm, preferably less than or equal to 5 mm. mm.

FIG. 11 further illustrates that the cross section (or geometrical section) of the aerodynamic tube 7 delimits a passage section S for the flow of air passing through the aerodynamic tube 7. This passage section S is here defined by the walls of the aerodynamic tube 7 and the segment extending in the alignment direction of the aerodynamic tubes 7 between the second profile 56 and the end 64 of the inner lip 18b.

This passage section S may have an area greater than or equal to 150 mm 2, preferably greater than or equal to 200 mm 2, and / or less than or equal to 700 mm 2, preferably less than or equal to 650 mm 2. A passage section S of the air flow in the relatively large aerodynamic tube 7 makes it possible to limit the pressure losses which would have the consequence of having to oversize the turbomachine used to obtain an air flow ejected by the opening 16 desired. . However, a large passage section induces a large size of the aerodynamic tube 7. Thus, with fixed pitch aerodynamic tubes, a larger passage section may affect the passage section of the induced air flow between the aerodynamic tubes 7 , thus not making it possible to obtain a satisfactory total flow of air directed towards the heat-transfer tubes 4.

In this first embodiment still, as can be seen in FIG. 10, so as to block as little as possible the flow of air towards the heat-transfer tubes 4 and the fins 8, the ventilation device 2 is advantageously arranged so that each aerodynamic tube 7 is vis-à-vis the front face 4f connecting the first 4a and second 4b planar walls of a heat pipe 4 corresponding.

As shown more particularly in Figure 10, the trailing edge 52 of each aerodynamic tube 7 is included in the volume defined by the first 4a and second 4b planar walls of the heat pipe 4 corresponding. Preferably, the second rectilinear portion 52a of the first profile 54 and the rectilinear portion 60 of the second profile 56 are respectively contained in the same plane (indicated in dotted lines in this FIG. 10) that the first plane wall 4a and the second plane wall 4b of the heat pipe 4 corresponding.

In particular, the distance f between the second rectilinear portion 52a of the first profile 54 and the portion 52b of the rectilinear portion 60 of the second profile 56 facing it is substantially equal to the distance separating the first wall 4a and the second wall 4b. heat transfer tube 4 vis-à-vis which the aerodynamic tube 7 is disposed. For example, this distance f is greater than or equal to 1 mm and / or less than or equal to 10 mm, preferably less than or equal to 5 mm.

In other embodiments not shown, the distance f between the second rectilinear portion 52a of the first profile 42 and the portion 52b of the rectilinear portion 60 of the second profile 56, which faces it, may however be less than the distance separating the first wall 4a and the second wall 4b of the heat transfer tube vis-à-vis the aerodynamic tube 7 is disposed.

However, as illustrated in FIG. 12, each ventilation tube 7 can be provided with misting devices 26 for misting a liquid in the flow of air F passing through the ventilation tube 7. These misting devices 26 are fed by a hydraulic circuit 28 of liquid supply, partially visible in this figure.

As illustrated in this figure, the foggers 26 may be oriented substantially below, in Figure 12, the end 64 of the second lip 18b. The foggers 26 are arranged for example at the top 65 of the curved portion 62 of the first profile 54 of the section of the tube 7.

Alternatively, the foggers 26 may in particular be arranged: substantially in the center of the section 48 of the ventilation tube 7, the foggers 26 being oriented to mist fluid towards the leading edge 50; in the vicinity of the trailing edge 52, in particular substantially between the first trailing edge wall 52a and the second trailing edge wall 52b, the misting devices 26 being oriented to mist fluid towards the leading edge 50; in the vicinity of the leading edge 50, in particular between the leading edge 50 and the end 64 of the second lip 18b, the misting devices 26 then being oriented in the direction of the opening 16; and / or under the curved portion 62 of the first profile 54, the misters 26 being oriented in a direction just below the end 64 of the second lip 18b. According to the example of FIGS. 10 to 12, the shape of the section 48 of the ventilation tubes 7, in particular the first profile 54 and even more precisely the second lip 18b and the curved portion 62 of the first profile 54, makes it possible to guide the flow of air F leaving the opening 16, by Coanda effect, so as to direct the air flow F substantially towards the heat transfer tubes 4 of the heat exchanger 1. This air flow F creates a suction phenomenon of a part of the ambient air A forming an induced flux I. In addition, the air flow F, containing a misted liquid, especially water, is cooled. Thus, the total air flow arriving on the heat-transfer tubes 4 and / or the fins 8 separating them, is cooler than in the absence of misting, thus improving the heat exchange capacities of the fins 8 and / or heat pipes 4 with the flow of air with which they are in contact. Other examples of forms of ventilation tubes are now described with reference to FIGS. 13 to 15. In the examples illustrated by these figures, as in the preceding examples, the ventilation tubes 7 extend in a substantially rectilinear manner, parallel between they, the tubes 7 can be aligned to form a row.

However, the cross section 48 of the ventilation tubes 7 comprises, in the case of these examples, a first profile 481 and a second profile 482, between the leading edge 50 and the trailing edge 52, which are symmetrical with respect to the DC plane connecting the leading edge 50 and the trailing edge 52. The distance c between the leading edge 50 and the trailing edge 52 is for example greater than 20 mm, preferably greater than 50 mm, and / or less than 80 mm, preferably less than 70 mm.

Each of the profiles 48i, 482 is provided with an opening 16. These openings 16 are similar to those of the example of FIGS. 10 to 12.

The symmetry of the profiles 481, 482 with respect to the plane CC passing through the leading edge 50 and the trailing edge 52 of the ventilation tube 7 makes it possible to limit the obstruction to the flow of air, between the ventilation device 2 and the heat-transfer tubes 4, while creating more air passages in the volume available in front of the heat-transfer tubes 4. In other words, as shown diagrammatically in FIG. 15, an air passage 58 conveying the ambient air A is created between each pair of 7 neighboring ventilation tubes. In contrast, in the example of Figure 10, an air passage is created between a pair of ventilation tubes 7 neighbors, out of two. For the rest, the operation of the cooling module comprising a ventilation device provided with ventilation tubes 7 as illustrated in FIGS. 13 and 14 is identical to the operation of the cooling module illustrated in FIG. 10. The airflow contacting the heat pipes 4 and / or the cooling fins 8 is however more important when the ventilation tubes 7 are as illustrated in Figures 13 and 14.

In the example of FIG. 13, the two profiles 481, 482 of the ventilation tube 7 converge towards the trailing edge 52 so that the distance separating the two profiles 481, 482 decreases strictly towards the trailing edge 52. Preferably, the two profiles 481, 482 each form an angle of between 5 and 20 ° with the plane CC of symmetry of the section 48.

As a result, contrary to the example of FIGS. 10 to 12, the section 48 does not include a portion delimited by first and second parallel opposed planar walls such as the first 52a and second 52b trailing edge walls. This has the advantage of limiting the drag along the section 48 of the ventilation tube 7.

For example, the maximum distance H between the two profiles 481, 482 is greater than 5 mm, preferably greater than 10 mm, and / or less than 30 mm, preferably less than 20 mm. In the illustrated example, this distance becomes zero at the trailing edge 52.

On the other hand, in the example of FIG. 14, the trailing edge 52 of each ventilation tube 7 comprises a trailing edge portion 68 delimited by first 52a and second 52b parallel plane trailing edge walls. However, these first 52a and second 52b flat trailing edge walls each extend, on the opposite side to the leading edge 50, by two convergent walls 70 so that the distance separating these walls 70 decreases strictly in the direction of the trailing edge 52. This makes it possible to limit the drag of the cross section 48 of the ventilation tube 7. In this example also, the maximum distance H between the two profiles 481, 482 may be greater than 5 mm, preferably greater than 10 mm, and or less than 30 mm, preferably less than 20 mm.

Finally, FIG. 16 illustrates a ventilation tube 7 of the ventilation device 2, integral with a heat-transfer tube 4 of the heat exchanger 1. In other words, the ventilation tube 7 and the associated heat-transfer tube 4 only form one and the same room. In what follows, however, the distinction between these two categories of tubes is maintained for the sake of comprehension.

Here, each ventilation tube 7 is connected to a heat-transfer tube 4 by a substantially planar connecting wall 72 extending from the trailing edge 52 of the ventilation tube 7. The connecting wall 72 preferably extends in a plane connecting the leading edge 50 to the trailing edge 52, this in order to limit as much as possible the disturbances of the flow of air from the opening 16, along the profiles 48i, 482.

In order to simplify the shape, and to reinforce the mechanical strength of the part formed by the ventilation tube 7 and the heat-transfer tube 4, the connecting wall 72 preferably extends in a plane parallel to the flat walls 4a, 4b of the tube coolant 4.

In the same way as in the case of the preceding examples, the ventilation tube 7 of FIG. 16, connected to the heat-transfer tube 4, can be obtained by folding, for example, by an aluminum foil, or by printing in three dimensions, in particular a metal material or a plastic material but also by molding or overmolding.

In this case also, the ventilation tube 7 may be equipped with a misting device 26 and a hydraulic circuit 28 for supplying the misting device 26, as the case may be. The misting device 24 thus formed is not shown in FIG. 16, for the purpose of legibility of this figure.

In the case where the ventilation tubes 7 are in one piece with a heat-transfer tube 4 corresponding, the intake manifold 5, on the one hand, and the fluid discharge manifold 6, on the other hand, can advantageously be made in one piece, each with an air intake manifold 12. For example, the air intake manifolds 12 may be integral with the fluid intake manifold 5 or the manifold 6. Again, the operation of the cooling module comprising such monolithic ventilation tubes 7 and heat transfer tubes 4 is substantially identical to the operating mode of the cooling module illustrated in FIG. 10, the flow of However, air in contact with the heat-transfer tubes 4 and / or the cooling fins 8 is more important in this case than in that illustrated in FIG. 10. The invention is not limited to the embodiments of FIG. sented and other embodiments apparent to those skilled in the art. In particular, any combination of the embodiments described above and their variants may be considered.

For example, in the examples described above, the foggers are nozzles. It can especially be high pressure nozzles. A high pressure nozzle consists of an orifice in a tube. Such a nozzle requires a high pressure of the liquid to be misted, upstream of the nozzle.

Alternatively, the foggers are nozzles at low pressures. A nozzle at low pressures consists of a hole in a tube, around which a flow of air is provided. The air flow makes it possible to entrain the liquid to be misted in the form of droplets. The air flow around the orifice makes it possible to overcome a too high liquid pressure upstream of the nozzle.

According to another variant, the foggers are impact nozzles. An impact nozzle consists of a tip on which liquid is sprayed with sufficient pressure to allow the formation of droplets.

Finally, the foggers can also be ultrasonic nebulizers. An ultrasonic nebulizer is a plate that is vibrated at an ultrasonic frequency to form liquid droplets. Such an ultrasonic nebulizer, by its size, is a priori more suitable for misting the liquid in the air intake manifolds, rather than in the ventilation tubes.

Moreover, in the examples presented above, the liquid is misted in the air flow F, upstream of the orifice 16 in the ventilation tube 7. However, according to a variant not shown, this misting of the liquid in the air flow F occurs downstream of the orifice 16 and, consequently, outside the ventilation tube 7. In this case, the misting device may open downstream of the orifice 16, in the direction flow of airflow F.

Claims (10)

A ventilation device (2) for generating a flow of air (F1) through a heat exchanger (1) of a motor vehicle, the ventilation device (2) comprising: a plurality of ducts (7) each comprising at least one opening (16) for passage of an air flow (F) passing through the corresponding duct (7), the air passage opening being configured so as to eject the airflow substantially in the direction of the heat exchanger (1), a supply circuit (12) of the airflow ducts (7), and at least one misting device (24) configured to generate droplets of a liquid in said air flow (F). 2. Ventilation device according to claim 1, wherein each opening (16) is delimited by a pair of guide lips (18) projecting from a wall (17) of the conduit (7) corresponding, each pair of guide lips (18a, 18b) being preferably configured to guide the flow of air (F), ejected through the opening (16), in a direction substantially perpendicular to a direction of extension of the duct (7) corresponding. Ventilation device according to claim 1, wherein each duct (7) has a section comprising: a leading edge (50), a trailing edge (52), opposite to the leading edge (50) and intended to disposed opposite the heat exchanger (2), first and second profiles (48i, 482, 54, 56), each extending between the leading edge (50) and the trailing edge ( 52), said at least one opening (16) of the duct (7) being on one of the first and second profiles (481; 482; 54), said at least one opening (16) being preferably in the vicinity of the leading edge (50), said at least one opening (16) being, more preferably, configured so that the air flow (F) passing through the conduit (7) and ejected by said at least one opening (16) flows along at least a portion of said one of the first and second profiles (481, 482; 54). 4. Ventilation device according to any one of the preceding claims, wherein the air flow supply circuit of the ducts (7) comprises at least one air intake manifold (12), preferably two collectors. air intake (12), the ducts (7) being connected to (s) said (s) air intake manifold (s) (12), in particular at their ends. 5. Ventilation device according to any one of the preceding claims, wherein the ducts (7) are substantially rectilinear, parallel to each other and aligned to form a row of ducts. 6. Ventilation device according to any one of the preceding claims, wherein the fogging device (s) (24) open: in the vicinity of the opening or openings (16), in particular upstream or downstream of the opening or openings ( 16) with respect to the flow direction of the air flow (F); and / or in the intake manifold (s) (12), especially in the vicinity of entries (14) of the ducts (7) from the intake manifold (s) (12); and / or in the ducts (7), in the vicinity of the openings (16) and / or in a passage section of the air flow (F) in the ducts (7). Ventilation device according to any one of the preceding claims, wherein the misting device (24) comprises one or more droplet generators (26) and a hydraulic circuit (28) for supplying the liquid or generators of droplets (26). 8. Ventilation device according to the preceding claim, wherein: the hydraulic circuit (28) comprises at least one portion extending in the plurality of ducts (7) and / or in the air intake manifold or heads ( 12); or the hydraulic circuit (28) is devoid of any portion extending into the plurality of conduits (7) and / or the intake manifold (12). 9. Ventilation device according to claim 7 or 8, wherein the one or more droplet generators (26) comprise at least one of: one or more high pressure nozzles; one or more nozzles at low pressures; one or more impact nozzles; and / or one or more ultrasonic nebulizers. 10. Cooling module (10) for a motor vehicle comprising a heat exchanger (1) and a ventilation device (2) according to any one of the preceding claims, the ventilation device (2) being adapted to direct the flow of heat. air (F) towards the heat exchanger (1).