FR3069621A1 - VENTILATION DEVICE FOR MOTOR VEHICLE - Google Patents

Abstract

The invention relates to a ventilation device for generating an air flow in the direction of a motor vehicle heat exchanger, comprising tubes (3), each tube (3) being provided with at least one opening of ejection of an air flow (F) distinct from its ends (6), at least one of the tubes (3) being pivotally mounted between a closed position and an open position, the ventilation device (1) being configured for closed, to let more air in the open position than in the position minus an air manifold (5) comprising an orifice (9), one of the ends (6) of the steerable tube (3) being mounted in said receiving port to form a fluid connection (30) between said at least one manifold (5) and said tube (3), a sealing member (20), and a compression mechanism (40) of the sealing member (20).

Description

VENTILATION DEVICE FOR A MOTOR VEHICLE

The subject of the invention is a ventilation device for a motor vehicle.

The invention relates to the automotive field, and more particularly to the field of air circulation for cooling the engine and its equipment.

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 designated by the term " fins "or" dividers ". The fins increase the exchange surface between the tubes and the ambient air.

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

Such a ventilation device most often comprises a propeller fan, which has several drawbacks.

First, the assembly formed by the propeller fan and its motorization system occupies a large volume.

In addition, the distribution of air ventilated by the propeller, often placed in the center of the row of tubes, is not uniform over the entire surface of the heat exchanger. In particular, certain regions of the heat exchanger, such as the ends of the heat transfer tubes and the corners of the heat exchanger, are not or only slightly affected by the air flow ejected by the propeller.

Furthermore, when it is not necessary to start the ventilation device, in particular when the exchange of heat with the ambient air is sufficient to cool the heat transfer fluid, the blades of the propeller obstruct or "mask" the part the flow of ambient air to the tubes and the fins. This limits the heat exchange between the ambient air, on the one hand, and the tubes and fins, on the other.

Another disadvantage is that, when the outside temperature is low or even negative, the propeller fan blows cold air on the heat exchanger, which has the effect of slowing the temperature rise of the vehicle engine.

In addition, in this case, the friction of the engine is reduced less quickly, which increases the consumption of the vehicle and therefore the emission of carbon dioxide.

An object of the invention is to provide a ventilation device for heat exchanger which does not have at least some of the drawbacks of ventilation devices for known heat exchanger.

To this end, the subject of the invention is a ventilation device intended to generate an air flow towards a heat exchanger of a motor vehicle, comprising tubes, each tube being provided with at least one opening for ejection of a separate air flow from its ends, at least one of the tubes being mounted orientable between a closed position and an open position, the ventilation device being configured to allow more air to pass in the open position than in the closed position, at least one air manifold for distributing the air to at least part of the tubes, said at least one air manifold comprising an orifice for receiving one of the ends of one of the tubes , said end of said tube being mounted in said receiving orifice so as to form a fluid connection between said at least one manifold and said tube, and a sealing element for sealing said connection fluidics.

Thus, advantageously, the plurality of tubes from which air is ejected makes it possible to replace the conventional propeller placed in front of the circulation tubes of a heat-transfer fluid from the heat exchanger, without having the drawbacks mentioned above.

Indeed, for equal heat exchange capacities, the volume occupied by such a ventilation device is much less than a propeller ventilation device. In addition, the distribution of air ventilated by the tubes is easier to control and can be made more homogeneous.

In addition, thanks to the device according to the invention, the obstruction of the flow of air to the heat exchanger is limited. In fact, the tubes of the ventilation device can advantageously be arranged facing zones of weak heat exchange of the heat exchanger, called "dead zones", such as the front faces of the tubes through which the heat transfer fluid passes, which does not are not in contact with cooling fins. This is not possible with a conventional propeller.

Furthermore, the invention makes it possible to offset the air ejection means supplying the tubes of the ventilation device with air flow, at a distance from the row of tubes for circulation of heat-transfer fluid, which offers more freedom in the design of the heat exchanger.

In addition, the ventilation device according to the present invention provides a function for shutting off the air intake as well as a function for ventilating the exchangers in a compact space allowing better thermal management of a motor vehicle, since the grille is blowing.

Depending on the orientation of the tubes, the device makes it possible to adjust the air flow which arrives at the heat exchanger, thereby optimizing thermal management.

In addition, the fluid connection between the manifold and the tube or tubes being sealed by the sealing element, preferably at least in the open position of the tubes, the energy efficiency of the ventilation device is improved, since the leaks between the manifold and the tube (s) are limited or even completely eliminated.

According to another characteristic of the invention, the compression mechanism comprises a ring at the end of the orientable tube and provided with a lug projecting axially in a longitudinal direction from the at least one orientable tube.

According to another characteristic of the invention, the compression mechanism comprises a housing for receiving the ring of the orientable tube.

According to another characteristic of the invention, the housing for receiving the ring comprises a lip for inserting the lug.

According to another characteristic of the invention, the device comprises a part carrying a plurality of receiving housings, each receiving housing being provided with an insertion flange.

According to another characteristic of the invention, the sealing element is a seal of circular cross section.

According to another characteristic of the invention, the compression mechanism comprises at least one pin projecting axially out of an axis of rotation of the orientable tube.

According to another characteristic of the invention, the compression mechanism comprises at least two pins projecting axially out of the axis of rotation of the orientable tube, an angular distance between two adjacent pins corresponding to a stroke of the tube orientable from one open or closed positions to the other closed or open positions.

According to another characteristic of the invention, the compression mechanism comprises at least one cavity for receiving a pin.

According to another characteristic of the invention, the compression mechanism comprises a part carrying a plurality of cavities for receiving a pin.

According to another characteristic of the invention, the sealing element is a joint of oblong section.

According to another characteristic of the invention, the sealing element is disposed in the receiving orifice of said at least one collector.

According to another characteristic of the invention, the tubes are positioned relative to each other so as to block an air flow in the closed position, and so as to allow a flow of air to flow in the open position.

According to another characteristic of the invention, each tube has a section comprising a leading edge, a trailing edge, opposite the leading edge, a first and a second profile, each extending between the leading edge and the trailing edge, said at least one opening of the tube being on one of the first and second profiles, said at least one opening being configured so that a flow of air leaving the opening flows along at least a portion of said one of the first and second profiles.

The invention also relates to a heat exchange module for a motor vehicle, comprising a ventilation device as described above, and a heat exchanger, the ventilation device and the heat exchanger being positioned one relatively to the other so that a flow of air set in motion by the ventilation device supplies air to the heat exchanger.

Other characteristics and advantages of the invention will appear on reading the description which follows. This is purely illustrative and should be read in conjunction with the accompanying drawings in which:

- Figure 1 illustrates a perspective view of a heat exchange module equipped with a ventilation device according to the present invention;

- Figure 2 illustrates a cross-sectional view of two tubes of Figure 1;

- Figure 3 illustrates a perspective view of another embodiment of the ventilation device in a first position;

- Figure 4 illustrates a perspective view of the ventilation device of Figure 3 in a second position;

- Figure 5 illustrates an exploded view of a part of the ventilation device of Figure 1 according to a first embodiment of the invention;

- Figure 6 illustrates an exploded view of details of Figure 5;

- Figure 7 illustrates a perspective view of part of the ventilation device of Figure 5 in a first position;

- Figure 8 illustrates a perspective view of part of the ventilation device of Figure 5 in a second position;

- Figure 9 illustrates a perspective view of the ventilation device of Figure 1 according to a second embodiment of the invention;

- Figures 10a and 10b illustrate a view of a tube of Figure 9 from two separate perspectives;

- Figure 11 illustrates a perspective view of a detail of a part of a compression mechanism of the ventilation device of Figure 9; and

- Figure 12 illustrates a detailed perspective view of a drive rod of the ventilation device of Figure 9.

Heat exchange module

The subject of the invention is a ventilation device 1 for a motor vehicle.

The invention also relates to a heat exchange module 100, comprising the ventilation device 1 and a heat exchanger 101.

As shown in Figure 1, the ventilation device 1 and the heat exchanger 101 are positioned relative to each other so that a flow of air set in motion by the ventilation device 1 supplies air the heat exchanger, preferably to cool the engine of the motor vehicle.

The ventilation device 1 is arranged upstream of the heat exchanger 101 in FIG. 1 (relative to an air flow coming from outside the moving vehicle).

However, the ventilation device can also be arranged downstream of the heat exchanger 101.

Ventilation device

As shown in the figures, the ventilation device 1 comprises a plurality of tubes 3.

The tubes are advantageously made of plastic material, or doped plastic, or metallic material.

Preferably, the tubes 3 are substantially rectilinear, mutually parallel and aligned so as to form one or more rows of tubes.

The set of tubes 3 constitutes a fan grille 8.

In the illustrated embodiments, the tubes 3 are distributed in two rows 8-1 and 8-2.

The ventilation device 1 also comprises a device for supplying air with an air flow F.

This device feeds the ventilation tubes 3 via an air supply circuit 4.

The air supply circuit 4 notably comprises two air intake manifolds 5 to which the ventilation tubes 3 are connected by means of air supply inlets located at each of their ends 6.

As can be seen in the figures, the two manifolds 5 extend parallel to each other, orthogonally to a longitudinal direction L along which the tubes 3 extend.

Each manifold 5 comprises a plurality of orifices 9.

Each orifice 9 is shaped to receive one of the ends 6 of the tubes 3.

Each end 6 of the tubes 3 is inserted into one of the receiving orifices 9 so as to form a fluid connection 30 between the manifold 5 and the tube 3.

Advantageously, the supply circuit also comprises one or more turbomachines 31 (illustrated in FIG. 9), for example a turbomachine arranged at the foot of each manifold, for ejecting the air through the intake manifolds 5, as far as the ventilation tubes 3 via the fluid connections 30.

The invention is now more particularly described in relation to FIG. 2.

As shown in FIG. 2, each ventilation tube 3 includes an opening 10 separate from the ends 6, for ejecting air from the tube 3.

Preferably, the openings 10 are intended to be arranged facing the heat exchanger.

As can be seen in FIG. 2, each tube 3 comprises a longitudinal wall 19, a cross section of which includes a free leading edge 11, a trailing edge 15 and a first and a second profile 12, 14, each extending between the leading edge 11 and trailing edge 15.

The trailing edge 15 is preferably arranged opposite the heat exchanger.

The longitudinal wall 19 is delimited by an internal surface 16 and an external surface 18.

Each opening 10 is made in the longitudinal wall 19 of the tube 3, preferably in one or the other of the profiles 12, 14.

In FIG. 2, each opening 10 is positioned close to the leading edge 11.

As also visible in Figure 2, the openings 10 of the pair of tubes 3 illustrated are formed in the profiles 12 facing each other.

Thus, the ventilation tubes 3 and their openings 10 are configured so that the air flow F circulating in the ventilation tubes 3 is ejected through the opening 10 by flowing along each profile 12, substantially up to at their trailing edges 52, by Coanda effect.

The flow of air F ejected from the tubes 3 makes it possible to accelerate another flow F ’in a direction of flow towards the heat exchanger.

Note that the cross sections of the tubes 3 are such that the profiles 12 extend in a direction of separation of the tubes 3 from the leading edges 11 to the trailing edges 15.

Orientable mounted tubes

At least one of the ventilation tubes 3 is mounted orientable, preferably pivoting.

In the illustrated embodiment, all the tubes 3 are pivotally mounted.

As shown in the figures, the tubes 3 are pivotally mounted between a closed position (Figure 3) and an open position (Figure 4), the closed position leaving a space between two adjacent tubes 3 less than a space between two adjacent tubes 3 in the open position.

In other words, the quantity of air circulating through the blowing grille 8 is greater in the open position than in the closed position.

In the illustrated embodiment, the tubes 3 are positioned relative to each other so as to block an air flow in the closed position, and so as to allow a flow of air to flow in the open position.

Of course, the invention is not limited to this configuration, and it is quite conceivable to provide a multitude of positions according to which more or less air passes through the tubes.

Thus, the ventilation device 1 has a function for shutting off the air inlet and a function for ventilating the exchangers in a compact space allowing better thermal management of a motor vehicle, since the grid is blower.

According to the orientation of the tubes, the device 1 makes it possible to adjust the air flow which arrives at the heat exchanger, which also makes it possible to optimize the efficiency of the heat exchanger.

Preferably, in the open position, the grid 8 blows air towards the heat exchanger 100 while in the closed position the grid 8 does not blow air.

Sealing

As particularly visible in FIGS. 5 to 11, the ventilation device 1 comprises at least one sealing element 20 and an associated mechanism 40 for compressing the sealing element 20.

In the illustrated embodiments, each sealing element 20 is a seal.

The compression mechanism 40 associated with each seal 20 makes it possible to seal the fluid connection 30, preferably in the open position of the tubes, as will be detailed.

As shown in the figures, each seal has a section whose shape corresponds to a section of the orifice 9, one section of which corresponds to a section of the associated end 6.

First embodiment

The invention is now described with reference to Figures 5 to 8.

According to this embodiment, each tube 3 has a circular section.

As seen particularly in FIG. 5, each seal 20 is placed in one of the orifices 9 of the manifold 5.

Each end 6 of the tube associated 3 with each orifice 9 comprises a ring 50 provided with at least one lug 51 projecting axially in the longitudinal direction L of the tube 3.

In the illustrated embodiment, the ring 50 is provided with two diametrically opposite lugs 51.

As can be seen particularly in FIGS. 7 and 8, the ring 50 has a first height H1 in the portions without lug 51 and a second height H2, greater than the first height H1, in the portions with lug 51.

The compression mechanism 40 also comprises a part 52 intended to cooperate with the lugs 51.

The part 52 comprises a column 53 hollowed out from several housings 54 for receiving the ring 50.

Each housing 54 comprises a curved portion 55 on which the ring 50 of the associated tube 3 rests.

The diameter of the curved portion 55 corresponds to the diameter of the circular tube 3.

The curved portion 55 is advantageously a semicircle.

Each housing 54 comprises a curved portion 56 adjacent to the curved portion 55 and extending between two ends 57.

The curved portion 56 has a smaller diameter than the curved portion 55, so that the housing 54 describes a shoulder 58 between the two curved portions 55 and 56, as visible in FIG. 5.

Each end 57 includes an insertion rim of an associated lug 51, referenced 58.

Each flange 58 has a height slightly less than the sum of the height H2 and the height H of the seal 20.

As shown in FIGS. 7 and 8, one of the seals 20 is installed in the periphery of the associated orifice 9, opposite the ring 50 of the end 6.

In the closed position, illustrated in FIG. 7, the lug 51 is located outside of the flange 58.

In this position, the seal 20 is arranged at a distance from the ring 50.

In other words, there is an axial clearance between the seal 20 and the ring 50.

In the open position, illustrated in FIG. 8, the lug 50 is located in the flange 58.

In this position, the ring 50 compresses the seal 20 against the manifold 5.

The operation of the ventilation device according to the first embodiment will now be described.

In the closed position, preferably, the turbomachines are stopped; no air is blown.

To activate the ventilation device 1, the turbomachines are put into operation.

The tubes 3 are pivoted around the longitudinal direction L from the closed position to the open position.

During pivoting, due to the axial play between the seal 20 and the ring 50, the tube 3 pivots freely, without mechanical resistance, as long as the lug 51 is at a distance from the flange 58.

Then, when the lug 51 enters the rim 58, the ring 50 is pressed against the seal 20 which is then compressed against the manifold 5, as already described.

In this position, there is no more play and sealing is ensured.

It is noted that it is preferable for the actuator to be powerful enough to ensure the pivoting of the tubes 3, including at the end of the travel, when the mechanical resistance becomes significant due to friction of the tube 3 on the manifold 5 via the pins 51 .

Second embodiment

The invention is now described with reference to Figures 9 to 12.

As shown in Figures 9, 10a and 10b, each tube 3 has an oblong section.

This oblong shape ensures better distribution of the air flow from the manifold to the tubes.

In addition, with an equal cross-section between a disc and an oblong hole, the oblong hole allows a denser stacking of the ejector tubes.

Each seal 20 has an also oblong shape.

Likewise, each orifice 9 of the manifold 5 has an oblong shape.

The tube 3 illustrated in FIGS. 10a and 10b comprises a body 60 extending between two opposite short edges 61, 62 and two opposite long edges 63, 64.

The short edge 61 corresponds to the open end 6 of the tube 3 and includes the air inlet 65 into the tube 3 via the associated orifice 9 of the manifold 5.

The inlet 65 of the short edge 61 is oblong, shaped to press the seal 20 against the manifold 5 by means of the compression mechanism 40, described later.

As also appears from Figures 10a and 10b, the tube 3 has three axes to ensure the movement of the tube 3 between the open and closed positions.

A first axis 66 is disposed in the short edge 61 and forms a vertex between the short edge 61 and the long edge 63.

The first axis 66 is adjacent to the inlet 65 of the tube 3.

The first axis 66 comprises a rod projecting axially along the longitudinal direction L towards the manifold 5.

A second axis 68 is carried by the short edge 62 and forms a vertex between the short edge 62 and the long edge 63.

The second axis 68 comprises a rod projecting axially along the longitudinal direction L towards a part 70 of the compression mechanism, described below.

Thus, the first two axes 66, 68 are substantially aligned with the long edge 63 along the longitudinal direction L.

As shown in FIGS. 10a and 10b, the compression mechanism of the seal comprises three pins 71 projecting axially from the second axis 68.

The angular distance between two adjacent pins 71 is chosen to correspond to a stroke of the tube 3 from one of the open or closed positions of the tubes to the other of the closed or open positions of the tubes.

In the embodiment illustrated in FIGS. 8 to 12, two adjacent pins 71 are angularly separated by an angle on the order of 60 °.

A third axis 72 is carried by the short edge 62, preferably in the middle of the short edge 62.

The third axis 72 is intended to cooperate with a drive rod 73, described later.

The third axis 72 comprises a rod projecting axially along a longitudinal direction parallel to the direction L, towards the part 70.

As already indicated, the compression mechanism 40 comprises the part 70 intended to cooperate with the pins 71.

As shown in FIG. 11, the part 70 comprises a plurality of housings 74.

Each housing 74 is shaped to receive the second axis 68 of the associated tube 3.

Each housing 74 includes three cavities 75 for inserting one of the pins 71 of the second axis 68.

Two adjacent cavities 75 are angularly spaced from one another in a similar fashion to the spacing between the two pins 71 with which they cooperate.

Thus, in the embodiment illustrated in FIG. 11, two adjacent cavities 75 are angularly separated by an angle on the order of 60 °.

The part 70 comprises a first part 76 in the form of a column and comprising the housings 74 arranged one under the other.

The part 70 also includes a second elongated part 77 parallel to the first part 78.

The first part 76 and the second part 77 are connected to each other by two joining parts 78.

The space 79 delimited between the parts 76, 77 and the two parts 78 is free, so that the drive rod 73 can move in the space 79.

In the closed position, each pin 71 is located outside the cavities 75.

In this position, the seal 20 is arranged at a distance from the short edge 61 of the tube 3.

In other words, there is an axial clearance between the seal 20 and the tube 3.

In the open position, each pin 71 is located in one of the cavities 75.

In this position, the short edge 61 compresses the seal 20 against the manifold 5.

As can be seen in FIG. 12, the drive rod 73 comprises a bar 80 which is substantially rectilinear.

The connecting rod 73 also comprises a plurality of control elements 81, each control element 81 being shaped to cooperate respectively with the third axis 72 of one of the tubes 3, respectively.

In the embodiment of FIG. 12, each control element 81 has a generally cylindrical shape.

A slot allows the passage of the bar 80, the bar 80 dividing the cylinder into two portions, 82 and 83.

The portion 82 is intended to accommodate the second axis 68 of one of the tubes 3 of the row 8-1 while the portion 83 is intended to accommodate the second axis 68 of one of the tubes 3 of the adjacent row 8- 2.

An opening 84 of the portion 82 and an opening 85 of the portion 83 allow the insertion of the second associated pin 68.

The tubes 3 of two adjacent rows are integral in movement with the drive rod 73, one of the second axes 68 being positioned in one of the portions 82, 83.

The ventilation device 1 also comprises an actuator 86 for setting in motion the drive rod 73.

The operation of the ventilation device according to the second embodiment will now be described.

In the closed position, preferably, the turbomachines are stopped; no air is blown.

To activate the ventilation device 1, the turbomachines are put into operation.

The tubes 3 are pivoted around the longitudinal direction L from the closed position to the open position.

To do this, the actuator 86 prints a vertical translational movement to the drive rod 73.

The second axes 68 being fitted into the cylinders of the connecting rod, each of the tubes 3 pivots by their first, second and third axes, towards the open position.

During pivoting, due to the axial clearance between the seal 20 and the short edge 61, the tube 3 pivots freely, without mechanical resistance, as long as the pins 71 are at a distance from the cavities 75.

Thus, thanks to the compression mechanism of the ventilation device 1 according to the present invention, it is possible to seal the fluidic connections when the ventilation device blows air while avoiding any friction during the pivoting of the tubes. between the open and closed positions.

The invention has been illustrated according to various embodiments, which, of course, are not limiting.

In particular, the tubes are not necessarily profiled to allow a coanda effect.

It is added that the embodiments are combinable insofar as they are not incompatible.

Claims (15)

1. Ventilation device intended to generate an air flow towards a heat exchanger of a motor vehicle, comprising: tubes (3), each tube (3) being provided with at least one ejection opening (10) of an air flow (F) distinct from its ends (6), at least one of the tubes (3) being mounted orientable between a closed position and an open position, the ventilation device (1) being configured to allow more air to pass in the open position than in the closed position, - at least one air manifold (5) for distributing air to at least part of the tubes (3), said at least one air manifold (5) comprising an orifice (9) for receiving one ends (6) of said at least one orientable tube, - said end (6) of said at least one orientable tube (3) being mounted in said receiving orifice (9) so as to form a fluid connection (30) between said at least one manifold (5) and said tube (3) , - a sealing element (20) for sealing said fluid connection (30), and - a compression mechanism (40) of the sealing element (20). 2. Ventilation device according to the preceding claim, wherein the compression mechanism (40) comprises a ring (50) of the end (6) of the orientable tube (3) and provided with a lug (51) projecting axially in a longitudinal direction of the at least one orientable tube (3). 3. Ventilation device according to the preceding claim, wherein the compression mechanism (40) comprises a housing (54) for receiving the ring (50) of the orientable tube (3). 4. Ventilation device according to the preceding claim, wherein the housing (54) for receiving the ring (50) comprises a flange (58) for inserting the lug (51). 5. Ventilation device according to one of claims 3 or 4, comprising a part (52) carrying a plurality of receiving housings (54), each receiving housing (54) being provided with an insertion flange (58 ). 6. Ventilation device according to one of the preceding claims, in which the sealing element (20) is a seal of circular cross section. 7. Ventilation device according to claim 1, in which the compression mechanism (40) comprises at least one pin (71) projecting axially out of an axis of rotation (68) of the orientable tube (3). 8. Ventilation device according to the preceding claim, wherein the compression mechanism (40) comprises at least two pins (71) projecting axially out of the axis of rotation (68) of the orientable tube (3), an angular distance between two adjacent pins (71) corresponding to a stroke of the orientable tube (3) from one of the open or closed positions to the other of the closed or open positions. 9. Ventilation device according to claim 7, in which the compression mechanism (40) comprises at least one cavity (75) for receiving a pin (71). 10. Ventilation device according to the preceding claim, wherein the compression mechanism (40) comprises a part (70) carrying a plurality of cavities (75) for receiving a pin (71). 11. Ventilation device according to one of claims 7 to 10, in which the sealing element (20) is a joint of oblong section. 12. Ventilation device according to one of the preceding claims, in which the sealing element (20) is arranged in the receiving orifice (9) of said at least one manifold (5). 13. Ventilation device according to one of the preceding claims, in which the tubes (3) are positioned relative to one another so as to block an air flow in the closed position, and so as to allow a flow of air in open position. 14. Ventilation device according to one of the preceding claims, in which each tube (3) has a section comprising: - a leading edge (11), - a trailing edge (15), opposite the leading edge (11), - a first and a second profiles (12, 14), each extending between the leading edge (11) and the trailing edge (15), said at least one opening (10) of the tube (3) being on one of the first and second profiles (12, 14), said at least one opening (10) being configured so that a flow of air leaving the opening (10) flows along at least a portion of said one of the first and second profiles (12, 14). 15. Heat exchange module for a motor vehicle, comprising a ventilation device according to one of the preceding claims, and a heat exchanger, the ventilation device and the heat exchanger being positioned one relative to the 'other so that an air flow set in motion by the ventilation device supplies air to the heat exchanger.