WO2019229374A1 - Ventilation device for a motor vehicle - Google Patents

Abstract

The invention relates to a ventilation device designed to generate a flow of air in the direction of a heat exchanger (1) of a motor vehicle, comprising: - tubes (3), each tube being provided with at least one opening for the emission of an air flow (F) and said opening being distinct from the ends of the tube, all the tubes together delimiting a so-called air supply grill, and - an atomising system (20) which is configured to generate a mist of droplets in said air flow.

Description

 VENTILATION DEVICE FOR MOTOR VEHICLE

The invention relates to a ventilation device for a motor vehicle.

The invention relates to the field of the automobile, 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 referred to as " fins "or" spacers ". The fins 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.

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

In the first place, the assembly formed by the propeller fan and its motorization device 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. Furthermore, when the start of the ventilation device is not necessary, especially when the heat exchange with the ambient air is sufficient to cool the heat transfer fluid, the blades of the propeller obstruct or "mask" in part 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.

Moreover, in this case, the friction of the engine is reduced less rapidly, 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 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 towards a motor vehicle heat exchanger, comprising tubes, each tube being provided with at least one opening of ejection of an air flow distinct from its ends, the set of tubes defining a so-called blowing gate, and a nebulizing system configured to generate a mist of droplets in said air flow.

Thus, advantageously, the plurality of tubes from which air is ejected makes it possible to replace the conventional propeller disposed in front of the circulation tubes of a heat transfer fluid 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.

In addition, thanks to the device according to the invention, the obstruction of the flow of air to the heat exchanger. In fact, the tubes of the ventilation device can advantageously be arranged facing areas of low heat exchange of the heat exchanger, called "dead zones", such as the end faces of the tubes through which the heat transfer fluid, 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 deport the air ejection means supplying air flow to the tubes 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.

In addition, the nebulization system of the device improves the energy performance of the heat exchanger with which it is associated, in particular by preparing the air blown on the heat exchanger at an optimum temperature. According to another characteristic of the invention, the nebulization system comprises at least one liquid fluid reservoir and at least one piezoelectric element configured to emit acoustic waves through said reservoir.

According to another characteristic of the invention, the device comprises a perforated membrane associated with the piezoelectric element.

According to another characteristic of the invention, the device comprises a nebulization nozzle associated with a piezoelectric element configured to emit acoustic waves.

According to another characteristic of the invention, the device comprises at least one air distribution manifold to the tubes, said manifold comprising a fog passage orifice generated by the nebulization system.

According to another characteristic of the invention, the device comprises a turbomachine for moving the fog. According to another characteristic of the invention, the reservoir is placed against the collector and / or against a housing of the turbomachine of the ventilation device.

According to another characteristic of the invention, each tube has a section comprising a leading edge, a trailing edge, opposite to the leading edge, a first and a second profile, each extending between the leading edge. and the trailing edge, said at least one aperture of the tube being on one of the first and second profiles, said at least one aperture being configured such that an airflow exiting the aperture 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 relative to one another. 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 an exploded perspective view of a heat exchange module equipped with a ventilation device, a nebulization system having been omitted;

- Figure 2 illustrates a cross-sectional view of two tubes of Figure 1; FIG. 3 illustrates a perspective view of the ventilation device of FIG. 1 equipped with a nebulization system according to a first embodiment;

FIGS. 4 and 5 show views respectively in longitudinal section and in perspective of a detail of FIG. 3; FIG. 6 illustrates a perspective view of a ventilation device according to another embodiment;

- Figure 7 illustrates a perspective view of a ventilation device according to another embodiment; FIG. 8 illustrates the reservoir of FIG. 6; and

- Figure 9 illustrates a nebulization system according to an alternative embodiment.

Heat exchange module

The invention relates to 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 can be seen in FIG. 1, the ventilation device 1 and the heat exchanger 101 are positioned relatively to one another so that a flow of air set in motion by the ventilation device 1 supplies air. the heat exchanger, preferably for cooling the engine of the motor vehicle.

The ventilation device 1 is disposed upstream of the heat exchanger 101 in Figure 1 (relative to a flow of air from outside the moving vehicle).

Nevertheless, the ventilation device may also be disposed 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 3 are substantially rectilinear, parallel to each other and aligned to form a row of tubes.

The ventilation device 1 also comprises an air supply device for an air flow F.

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

The air supply circuit 4 comprises in particular two air intake manifolds 5-1, 5-2 to which the ventilation tubes 3 are connected by means of air supply inlets located at each of their ends 6, 7. Advantageously, the supply circuit also comprises one or more turbomachines 26 for ejecting the air through the intake manifolds 5-1, 5-2, into the ventilation tubes 3.

In FIG. 3, a turbine engine 26 is arranged at the bottom of the ventilation device 1 in a housing 27. The two collectors 5-1, 5-2 are joined at the level of the turbomachine 26 so that the two collectors describe a shape of U.

Of course, the invention is not limited to this curved configuration of the collectors 5-1, 5-2.

It is entirely possible, for example, for each collector 5-1, 5-2 to be rectilinear, and for a respective turbomachine 26 to be dedicated to each collector, being placed at the foot of the associated collector 5-1, 5-2, as shown in Figures 6 and 7.

As more particularly visible in FIG. 2, each ventilation tube 3 comprises an opening 10 distinct from the ends 6, 7 for ejecting the air out of 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 50, a cross section comprising a free leading edge 1 1, a trailing edge 15 and first and second profiles 12, 14, each extending between the leading edge 11 and the trailing edge 15. The trailing edge 15 is preferably arranged opposite the heat exchanger.

The longitudinal wall 19 is delimited by an inner surface 16 and an outer surface 18.

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

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

As also visible in Figure 2, the openings 10 of the pair of tubes 3 shown are formed in the profiles 12 facing each other. Thus, the ventilation tubes 3 and their openings 10 are configured so that the flow of air F flowing in the ventilation tubes 3 is ejected through the opening 10 by flowing along each profile 12, substantially until at their trailing edges 52, by Coanda effect.

The flow of air F ejected from the tubes 3 accelerates another flow F 'in a direction of flow to the heat exchanger.

It should be noted that the transverse cross-sections of the tubes 3 are such that the profiles 12 extend in a direction away from the tubes 3 from the leading edges 11 to the trailing edges 15.

Nebulization system As can be seen in FIGS. 3 to 9, the ventilation device 1 comprises a nebulization system 20.

The system 20 generates a mist B of droplets in the air flow F to the tubes 3.

The fog allows efficient thermalization of the air F which blows over the entire surface of the heat exchanger 101, which improves the thermal efficiency of the heat exchanger. In particular, according to the difference in humidity between the air and the droplets, the air evaporates the droplets, which ensures its cooling (there is evaporation until the relative humidity of the air is 100 %).

The system 20 comprises a reservoir of liquid fluid, preferably water, referenced 21. In FIGS. 4 to 7, the reservoir 21 is installed against the housing 27 of the turbomachine 26 and the collector 5-1, which makes it possible to limit the size of the nebulization system 20.

As is apparent from these figures, the reservoir 21 has a shape adopting the local shapes of the housing 27 and the collector, which further reduces the size of the system 20.

In Figures 3 to 5, the reservoir is disposed in the curvature of the collector 5-1.

In Figure 7, the reservoir has a substantially annular section and around the housing 27, to fit in the maximum size of the collector 5-1.

As is also apparent from FIGS. 3 and 4, the tank 21 is pierced with a hole 22 for passing fog B.

Similarly, the collector 5-1 is pierced with a hole 8 for passing the mist B into the collector 5-1, where the mist is entrained in the tubes 3 and ejected through the orifices 10 to the heat exchanger.

The tank 21 comprises a circuit 23 for driving the fog B.

As illustrated in FIG. 4, the driving circuit 24 comprises a orifice 25 of the housing 27, an orifice 28 of the reservoir 21 opposite the orifice of the housing 27, and the orifice 22.

The openings of the housing and the tank allow a tapping of a part of the air flow F set in motion by the turbine engine enters the tank 21, which allows the fogging B out of the tank 21 into the manifold 5- 1.

In the variant of FIG. 8, the tank 21 comprises a turbomachine 26 'dedicated to driving the fog B out of the tank 21 in the manifold 5-1. According to this variant, no tapping is necessary at the reservoir.

The reservoir is also identical to that of the first variant.

Piezoelectric element

As can be seen from the figures, the nebulizing system 20 also comprises at least one piezoelectric element 30 configured to emit acoustic waves through said reservoir.

For example, the device 1 comprises up to twenty piezoelectric elements, distributed in one or more reservoirs 21, as a function of the flow of water supplied by each, the total flow of water generally being between 1 and 5 ml / s.

Preferably, the vibration frequency of the piezoelectric element is between 1 and 3 MHz, which gives droplets of average diameter 5 to 20 μm.

These droplets, of small dimensions, are easily evaporated by the flow of air.

According to another variant, the vibration frequency of the piezoelectric element is between 20 and 100 kHz, which generates droplets of diameter of the order of 100 miti.

According to an embodiment illustrated in the figure, the nebulization system comprises a nozzle 40, one end of which is a perforated membrane 41. The water is extruded through the perforated membrane to form the droplets of the mist B. The size of the drops depends the size of the orifices of the grid. The flow depends only on the vibration frequency of the piezoelectric element.

The nozzle 40 forms a concentrator of vibratory waves emitted by the piezoelectric element.

As can be seen in FIG. 9, the nebulizing system 20 also comprises a hydraulic circuit 42 for conveying water into the nozzle 40.

The hydraulic circuit 42 comprises a pump 43 for moving water between the reservoir 20 and the nozzle 41.

Advantages

As already apparent from the description, the configurations according to the present invention can effectively cool the air for cooling the heat exchanger. In the case where all the droplets are not evaporated, they will stick to the wall of the exchangers. This will increase the performance of the exchanger, by drawing the energy of the coolant by evaporation of the water film. Finally, in the case where several exchangers are placed in series in the cooling module, the benefits of the misting are found for each exchanger (including temperature drop on each exchanger).

It is added that the embodiments are combinable to the extent that they are not incompatible.

Claims

A ventilation device for generating a flow of air towards a heat exchanger (1) of a motor vehicle, the ventilation device comprising: tubes (3), each tube being provided with at least one opening ejecting (10) an air flow (F) distinct from its ends (6, 7), the set of tubes defining a so-called blowing gate, and a fogging system configured to generate a fog of droplets in said air stream (F). 2. Ventilation device according to the preceding claim, wherein the nebulizing system (20) comprises at least one reservoir (21) of liquid fluid and at least one piezoelectric element (30) configured to emit acoustic waves through said reservoir ( 21). 3. Ventilation device according to the preceding claim, comprising a perforated membrane (41) associated with the piezoelectric element (30). 4. Ventilation device according to claim 1, comprising a nebulizing nozzle (40) associated with a piezoelectric element (30) configured to emit acoustic waves. Ventilation device according to one of the preceding claims, comprising at least one collector (5-1, 5-2) for distributing air to the tubes (3), said manifold comprising a fog passage (8) generated by the nebulizing system (20). 6. Device according to one of the preceding claims, comprising a turbomachine (26) for moving the fog. 7. Ventilation device according to the preceding claim, wherein the reservoir (21) is pressed against the collector (5-1, 5-2) and / or housing (27) of the turbomachine (26) of the ventilation device (1). 8. Ventilation device according to one of the preceding claims, wherein each tube (3) has a section comprising:  a leading edge (1 1),  a trailing edge (15) opposed to the leading edge (1 1),  first and second profiles (12, 14), each extending between the leading edge (11) and the trailing edge (15),  said at least one aperture (10) of the tube (3) being on one of the first and second profiles (12, 14), said at least one aperture (10) being configured so that a flow of air exiting from the opening (10) flows along at least a portion of said one of the first and second profiles (12, 14). 9. 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 another so that a flow of air set in motion by the ventilation device supplies air to the heat exchanger.