FR3108304A1 - Vehicle equipped with a front inlet-vertical outlet air duct - Google Patents

Abstract

Vehicle equipped with a front inlet-vertical outlet air knife duct The invention relates to a vehicle equipped with an air knife duct (C). The air inlet (E) of the duct (C) faces the front of the vehicle and has a slot (FE) whose height (HE) is a dimension of a few centimeters in height. The outlet (S) of the duct (C) ejects air upwards following an outlet slit (FS) whose height (HS) is of a dimension of a few millimeters to 1 cm, in the order of 5 mm. . The air ejection speed is a function of the ratio of the area of the section of the air inlet slot (FE) divided by the area of the section of the ejection slot (FS) of the air. When the ejection slot (FS) is installed in the awning (AV) of a motor vehicle, this air ejection helps protect the windshield (PB) against rain. Figure to be published with the abstract: Fig. 1.

Description

Vehicle equipped with a front entry-vertical exit air gap duct

FIELD OF THE INVENTION TO WHICH THE INVENTION RELATES

The invention relates to a system for reducing the drag in particular of a land vehicle.

PRIOR ART

The aerodynamics of vehicles has always been the subject of optimization research, in particular the drag coefficient Cx and the value of the SCX reflecting the resistance to the advancement of the vehicle as a function of its frontal surface S.

During the 14-18 war, Constantin Chilowski seeks to influence the flow of air around a moving shell by a jet leaving perpendicular to the axis of the shell, in order to reduce the resistance that the shell air opposes projectiles.

In 2014, the structure of a flying car project is still evolving, with the use during cruise phases of the Chilowski effect consisting in projecting a thin jet of pressurized air, normal to the flow, on the nose and the leading edges, then covering most of the surface wetted by the Coandă effect.

In 2017, the patent FR1756685 proposed its application for a land vehicle.

In this patent, the source of the projected air is a compressed gas generator.

This solution appears difficult to implement with regard to the volume of gas to be generated and would produce nuisances on board the vehicle.

For example, propelling air at 200 m/s through a 5 mm slot 1 meter wide would represent 1,000 liters of air per second.

In addition, the aerodynamic gain is fragile insofar as the energy to be devoted to compress the air and to project it must be less than the energy saved by the drag reduction.

In fact, the efficiency of such a compressed gas generator is much lower than the 100% of a perfect machine. If this generator is driven by the engine, it is already necessary to take into account the efficiency of the heat engine much lower than 1 to be multiplied by the efficiency of the mechanical compressor also lower than 1. Similarly if the variant consists in using a turbo- compression activated by the exhaust gases of the internal combustion engine.

Furthermore, the flow of air ejected vertically is placed at the front of the front bumper and completely disturbs the flow of fresh air which must pass through the air intakes of the grille to reach the aerothermal front of the engine in order to ensure its cooling.

BRIEF DESCRIPTION OF THE INVENTION

The vehicle has a drag reduction system comprising an air gap duct, the air inlet of which faces the front of the vehicle and comprises an inlet slot with a dimension of a few centimeters in height and the outlet of which ejects air upwards following an exit slit of a few millimeters to 1 cm in height, the air ejection speed being a function of the ratio of the surface area of the section of the air inlet slot divided by the sectional area of the air outlet outlet slot.

The ratio of the cross-sectional area of the air inlet slot divided by the cross-sectional area of the air ejection outlet slot can be between 4 and 10.

The air ejection speed at the outlet can be between 150 meters per second and 250 meters per second.

As an alternative to a simpler fixed geometry, the height of the air inlet slot can be variable and controllable depending on the speed of the vehicle.

In particular, the vehicle may be a land motor vehicle.

In this case, the width of the air inlet slot is of the order of the width of the aerothermal front of the vehicle.

As for the width of the air ejection slot, it can be between the width of the aerothermal front of the vehicle and the width of the windshield.

The air intake can be arranged as a scoop on the bonnet, but the location of the air intake is preferably in the engine compartment.

When the air intake is located in the engine compartment and shares the air admitted by the grille, it is advantageous for the system to modulate the distribution of the air entering the engine compartment between the air intended to cool the engine and air intended to reduce aerodynamic drag.

In this case, the system input parameters are vehicle speed, outside air temperature and engine temperature.

It is preferable that the air is ejected at a height greater than the aerothermal front so as to avoid disturbing the cooling of the engine.

According to one embodiment, the air ejection slot and the front edge of the cover coincide.

According to another embodiment, the air ejection slot opens into the cowl of the vehicle at the base of the windshield.

It is then possible to use the cover as the upper face of the duct, which means that the duct partly runs along the cover.

This contributes to the sound insulation of the engine compartment towards the outside of the vehicle.

This also makes it possible to contribute to compliance with the standard impacting the head of a pedestrian on the bonnet.

In addition, the fact that the air projection at the exit of the ejection slot is positioned in the cowl of the vehicle at the base of the windshield contributes to the protection of the windshield against the rain.

Other characteristics and advantages of the invention will appear on reading the detailed description which follows for the understanding of which reference is made to the appended drawings.

shows according to the invention a duct with a fixed geometry of an air gap whose air inlet faces the front of the vehicle and the outlet ejects air upwards.

shows according to the invention a duct of an air gap whose air inlet faces the front of the vehicle with a height that can be adjusted by a controllable flap and the outlet ejects air upwards.

shows a conventional motor vehicle in a front three-quarter perspective view.

shows a conventional motor vehicle from a side view, showing the interior of the engine compartment.

specifically shows the engine compartment of a conventional motor vehicle.

shows an example of the installation of the duct with the air inlet in a scoop on the hood.

shows an example of installation in front of the duct with the air inlet in the engine compartment.

shows an example of the installation of the duct with the air intake in the engine compartment and whose ejection slot coincides with the front cutout of the bonnet.

shows in perspective a vehicle in the example of the previous installation of the duct with the air inlet in the engine compartment and whose ejection slot coincides with the front cutout of the bonnet.

shows an example of the layout of the duct with the air intake in the engine compartment and the ejection slot in the cowl.

DETAILED DESCRIPTION OF THE INVENTION

The vehicle (V) has a drag reduction system (S) comprising a conduit (C) for an air gap.

The air inlet (E) of the duct facing the front of the vehicle has a slot (FE) whose height (HE) is a few centimeters high.

The outlet (S) of the duct (C) ejects air upwards following an outlet slot (FS) whose height (HS) is of a dimension of a few millimeters to 1 cm, in order of magnitude 5 mm .

The air ejection velocity is a function of the ratio of the cross-sectional area of the air inlet slot (FE) divided by the cross-sectional area of the ejection slot (FS). air.

The ratio of the area of the section of the air inlet slot (FE) divided by the area of the section of the outlet air ejection slot (FS) can be between 4 and 10.

The air ejection speed at the outlet can be between 150 meters per second and 250 meters per second.

By way of example, the height (HE) of the air inlet (E) can be 3 cm, which represents a ratio of 6 for an ejection slot (FS) with a height (HS) of 5mm.

If the speed of the vehicle is 90 km/h or 25 m/s, this gives multiplied by 6, 150 m/s.

If the speed of the vehicle is 120 km/h or 33.33 m/s, this gives multiplied by 6, 200 m/s.

If the speed of the vehicle is 150 km/h or 41.66 m/s, this gives multiplied by 6, 250 m/s.

Figure 1 shows one embodiment of the conduit which is a fixed geometry.

The duct (C) in this case comprises an air inlet (E), a fitting (R) which changes the direction of the air flow and an air ejection outlet (S).

The air inlet (E) is in this embodiment a prism with trapezoidal bases whose initial height, for example 3 centimeters, gradually decreases to 5 mm over about ten centimeters.

The fitting (R) has the shape of an elbow to modify the 90° orientation of the incoming air flow captured frontally and exiting vertically.

The air outlet (S) thus allows the air to be projected upwards.

Of course, the slots (FE) and (FS) represented with flat rectangular sections can in practice be curved according to the volumes of the vehicle, in particular the curvature of the front face (FA), the curvature of the bonnet (CA) and the curvature of the windshield (PB), none of these parts being generally flat.

The distance between the upper duct wall and the lower duct wall can be maintained by studs or thin vertical partitions offering little resistance to airflow.

As an alternative to a simpler fixed geometry, the height (HE) of the air inlet slot (FE) can be variable and controllable as a function of vehicle speed (V).

This is shown in Figure 2. By way of example, the underside of the air inlet prism (E) is in fact a mobile flap (VM) pivoting around an axis (A).

The height (HE) of the air inlet slot (FE) then becomes controllable by a controllable movable flap (VM).

Conventionally, it may be a motorization of the mobile shutter (VM) by stepper motor, similar to that of the heating/air conditioning group shutters or the active grille shutters.

Then the ratio that has become controllable makes it possible to manage, depending on the speed of the vehicle (V), the air ejection speed which must remain subsonic to maintain the speed acceleration effect.

Otherwise, there would be a sonic neck effect which would be harmful insofar as the resistance to the advancement of the front air intake would increase without the ejection speed limited to the speed of sound increasing and therefore without additional reduction of the trainee.

In particular, the vehicle (V) can be a conventional land motor vehicle as shown synthetically in perspective in Figure 3 and in side view in Figure 4 with an enlarged view of the engine compartment (CM) in Figure 5.

Most commonly, these are vehicles with internal combustion engines (M), knowing that there are also hybrid or all-electric versions.

The control electronics of the system (S) in its controllable version can of course be produced by a dedicated electronic box, but in modern vehicles it is more appropriate for this to be part of the functions of the engine control box or a box central cabin such as an intelligent service box.

In Figure 3, the windshield (BP) is noted in particular, as well as its width (LP) essentially at its base with a typical dimension between 1m30 and 1m40.

Depending on the model, the bonnet (CA) may be shown with its bonnet line (LC) which is the front edge of the bonnet, at the height of the lights. The hood (CA) can be made shorter with a hood line (LC) higher and closer to the windshield (PB). On other models, the bonnet (CA) can on the contrary be more imposing and embed the grille, the bonnet line (LC) then descending to the front bumper.

Air inlets (EA) arranged on the front face (FA) cool the engine. Their number and shapes contribute to the visual appearance of the grille, which often contributes to the visual identity of the car brand independently of its technical function.

Figure 4 shows a land vehicle with combustion engine in side view with internal view of the engine compartment (CM), zoomed in figure 5.

This engine compartment (CM) is the space comprised longitudinally between the front face (FA) and the apron (T), and in height between the lower ground clearance limit which can be materialized by a shoe or an aerodynamic fairing and the cover (CA).

Conventionally, the engine compartment (CM) includes the engine (M) represented without accessories to be completed, in particular with its air intake line, its exhaust line and a gearbox to make the complete powertrain. .

It also comprises for its cooling an aerothermal facade comprising a radiator (RA) and a fan (VE).

This aerothermal facade has a width (LF) of the order of 80 cm to 1 meter and is placed behind the grille.

Fresh outside air arrives frontally at the radiator via the air inlet spaces (EA) in the grille of the vehicle (V).

As for the cowl (A), it represents a different space to house the windscreen wiper mechanisms and to be used for the air intake of the air conditioning unit.

FIG. 6 illustrates a first embodiment of the system (S) for reducing the drag of the vehicle (V).

In this first embodiment, the air intake of the air inlet (E) is outside the hood, scoop similarly to some engine intake air intakes of competition models .

The air inlet (E) can thus be arranged as a scoop on the hood (CA) but in a preferred manner, the location of the air inlet (E) is in the engine compartment (CM).

FIG. 7 illustrates a second embodiment of the drag reduction system (S) of the vehicle (V) in which the air intake (E) is located in the engine compartment (CM) at the front of the vehicle ( V).

In this case, the width (LE) of the air inlet slot (FE) is of the order of the width (LF) of the aerothermal front of the vehicle (V) to make maximum use of the available width, around '1 meter.

As shown, the system (S) has a dedicated air intake (E), separate from the air intakes (EA) of the grille to the engine.

When, on the other hand, the air intake (E) is located in the engine compartment (CM) and shares the air admitted by the grille, it is advantageous for the system (S) to modulate the distribution of the air entering the the engine compartment (CM) between the air intended to cool the engine (M) and the air intended to reduce aerodynamic drag.

This distribution can be modulated by a dedicated mobile shutter (VM).

In this case, the system input parameters are the vehicle speed (V), the outside air temperature and the engine temperature (M).

In particular, engine cooling is preferred when the vehicle (V) is stationary in traffic jams in town during the heat wave.

On the contrary, the aerodynamics of the vehicle (V) are favored when the vehicle is driven at high speed in cool weather.

It is preferable that the air is ejected at a height greater than the aerothermal front so as to avoid disturbing the cooling of the motor (M).

Figure 8 illustrates a third embodiment in which the air ejection slot (FS) and the front edge (LC) of the cover (CA) coincide. This has the advantage of not creating an additional air ejection line on the bonnet (CA).

The clearance usually left between the front face (FA) and the front of the cover (CA) is already a few millimeters and allows the air ejection outlet slot (FS) to be positioned in the same location.

Figure 9 illustrates the consequences on the vehicle (V) of the displacement of the line (LC) of the bonnet (CA) intentionally from a technical point of view, independently of the design.

Figure 10 illustrates a fourth and final embodiment in which the air ejection outlet slot (FS) opens into the cowl (A) of the vehicle (V) at the base of the windshield (PB).

It is then possible to use the cover (CA) as the upper face of the duct (C) at its connection (R), which means that the duct (C) partly runs along the cover (CA).

This contributes to the sound insulation of the engine compartment (CM) towards the outside of the vehicle (V).

This also makes it possible to contribute to compliance with the standard impact of a pedestrian's head on the bonnet (CA) in the event of a frontal collision with a pedestrian.

Furthermore, the fact that the air projection at the exit of the ejection slot is positioned in the cowl of the vehicle at the base of the windscreen can contribute to the protection of the windscreen against the rain.

Indeed, in the event of rain, the speed of the raindrops is generally less than 10 m/s and therefore an air flow projected at more than 150 m/s will carry the raindrops upwards thereby sparing partly the windshield (BP).

In this configuration, the width (LS) of the exit slot (FS) will be close to the width (LP) of the windshield (BP).

For example, it is advisable to increase the height (HE) of the entrance slot (FE) from 3 to 4 centimeters to obtain the same multiplication ratios of the order of 6 for a height (HS) 5 mm despite a width (LS) of 133 cm compared to a width (LE) of 1 meter.

All of the embodiments of the system (S) can always be sophisticated by controlling at least one mobile shutter (VM).

A first control parameter is the vehicle speed (V).

On the one hand, the speed of the vehicle which is that of the inlet speed of the air gap conditions the opening of a flap (VM) to obtain at a given speed the same air outlet speed projected or a setpoint depending on the speed of the vehicle (V).

On the other hand, the speed of the vehicle also intervenes in the interest of the aerodynamic optimization itself of the vehicle which is low in town at less than 50 km/h and high on the motorway at 130 km/h or even more depending on countries.

In addition, in town at less than 50 km/h, you may wish to limit or inhibit the system, for example depending on possible noise pollution.

Moreover, the climatic conditions can be taken into account to modulate or inhibit the system (S) according to the meteorology. This can be done by taking into account whether or not the wipers are activated. For the most sophisticated vehicles, data can be taken from the rain sensor when it exists and from the outside temperature to modulate or inhibit the system (S) in the presence of rain or snow.

In terms of industrial application, the drag reduction system according to the invention relates in particular to motor vehicles (V) with a thermal engine (M).

The present invention is in no way limited to the embodiments described and represented, but those skilled in the art will be able to add any variant to it in accordance with their spirit for a range of technical solutions in different fields.

Claims (10)

Vehicle (V) characterized in that it has a system (S) comprising a duct (C) of an air gap whose air inlet (E) faces the front of the vehicle ( V) and comprises a slit (FE) with a dimension (HE) of a few centimeters in height and that its outlet (S) ejects air upwards following a slit (FS) of a few millimeters to 1 cm in height (HS), the air ejection speed being a function of the ratio of the area of the section of the air inlet slot (FE) divided by the area of the section of the outlet slot (FS) d ejection of air. Vehicle (V) according to Claim 1, characterized in that the ratio of the area of the section of the inlet slot (FE) divided by the area of the section of the outlet slot (FS) for ejecting the air can be between 4 and 10. Vehicle (V) according to any one of Claims 1 to 2, characterized in that the air ejection speed at the outlet can be between 150 meters per second and 250 meters per second. Vehicle (V) according to any one of Claims 1 to 3, characterized in that the height (HE) of the air inlet slot (FE) is variable and controllable as a function of the speed of the vehicle (V) . Vehicle (V) according to any one of Claims 1 to 4, characterized in that the vehicle (V) is a land motor vehicle. Vehicle (V) according to Claim 5, characterized in that the installation of the air intake (E) is positioned at the front in the engine compartment (CM). Vehicle (V) according to any one of Claims 5 to 6, characterized in that the air is ejected into the cowl (AV). Vehicle (V) according to Claim 7, characterized in that the duct (C) partly runs along the hood (CA) participating in the sound insulation of the engine compartment (CM) towards the outside of the vehicle (V). Vehicle (V) according to Claim 7, characterized in that the duct (C) partly runs along the bonnet (CA) contributing to compliance with the standard impact on the head of a pedestrian on the bonnet (CA). Vehicle (V) according to Claim 7, characterized in that the projection of air at the exit from the ejection slot (FS) participates in the protection of the windscreen (PB) against the rain.