FR3059975A1 - SELF-ADAPTIVE DEFLECTOR FOR MODIFYING THE AERODYNAMIC CHARACTERISTICS OF A MOTOR VEHICLE - Google Patents

Abstract

A system for modifying the aerodynamic characteristics of a motor vehicle comprising at least one flap (100) defining an inner surface and an outer surface of the flap, the flap (100) being configured to increase the vehicle's offset, being movable between at least a folded position in which the inner surface of the flap is placed against a trailing edge of the outer surface of the vehicle and an extended position as a function of an air pressure on the outer surface of the flap, characterized in that the system comprises active control means (110) for enabling or blocking a passage between the folded position and the unfolded position as a function of instantaneous information (120) relating to the dynamics of the vehicle.

Description

Holder (s): PEUGEOT CITROEN AUTOMOBILES SA Société anonyme.

Extension request (s)

Agent (s): PEUGEOT CITROEN AUTOMOBILES SA Public limited company.

SELF-ADAPTIVE DEFLECTOR FOR MODIFYING THE AERODYNAMIC CHARACTERISTICS OF A MOTOR VEHICLE.

FR 3 059 975 - A1

System for modifying the aerodynamic characteristics of a motor vehicle comprising at least one flap (100) defining an internal surface and an external surface of the flap, the flap (100) being configured to increase the downforce of the vehicle, by being movable between at least a folded position in which the internal surface of the flap is placed against a trailing edge of the external surface of the vehicle and a position deployed as a function of air pressure on the external surface of the flap, characterized in that the system comprises active control means (110) for enabling or blocking a passage between the folded position and the unfolded position as a function of instant information (120) relating to the dynamics of the vehicle.

100

SELF-ADAPTIVE DEFLECTOR FOR MODIFYING THE AERODYNAMIC CHARACTERISTICS OF A MOTOR VEHICLE The invention is part of the context of automobile aerodynamics, and aims to increase the support of the vehicle, that is to say, to search a gain in downforce, in order to improve grip on the ground to obtain better performance and improve vehicle safety.

The invention also fits into the context of biomechanics, that is to say that it is inspired by the mechanics of life, in this case the behavior of bird wings during the phases landing.

We know that some bird feathers have self-adaptive behavior depending on the angle of attack of the wing. Thus, during transient phases requiring a high angle of attack, secondary feathers are naturally raised with the depression generated on the upper surface, that is to say the upper part of the wing, and act as a deflector, which allows them to increase lift and avoid dropping out.

When a wing is in a flow subjected to different angles, a swirling zone exists on the upper surface of the wing starting from the trailing edge of the wing and gradually increasing towards the leading edge plus the tilt is great. This vortex area, called recirculation, has very low pressure. As a result, at high angles of inclination the wing stalls, that is to say that the lift force is no longer sufficient to maintain the wing at altitude, due to the extent of the recirculation on the wing. The feathers serve as a device to delay dropping out by self-adaptation. They rise due to a strong depression generated on the upper surface of the wing, opposing this recirculation.

It has been shown in the field of aeronautics that the effect of the use of a self-adapting deflector on an aircraft wing makes it possible to gain lift when the wing is strongly inclined. This application therefore proves to be essential for aeronautics with a view to increasing lift but it should be noted that the majority of studies observe a decrease in drag. Several parametric studies on this type of deflector have shown that at low angle of attack, the addition of a self-adapting deflector did little or no harm to lift and aerodynamic drag. For critical angles of attack, of the order of 10 ° to 20 °, the depression which rises along the upper surface causes the deflector to rise and provides lift gains of up to 20% and drag gains up to 50%.

Transposing the ideas developed in aeronautics to the automobile field, some authors have succeeded in reducing the drag of an Ahmed body to 25 °, which is the theoretical form of a vehicle, by using a self-adjusting deflector on the bezel. This shows the interest that this device can have for the automotive sector which seeks to reduce the drag of these vehicles.

Such mechanical deflectors are called in the English-language literature: "self activated movable flap", "self actuating flap", "self adaptive flap", "automatic movable deflector", or even "upper surface spoiler".

The vortex structures move away from the base of the vehicle with the use of a self-adapting deflector. There is an attenuation of the longitudinal vortices with a deflector downstream of Ahmed's body. It would be this attenuation and the increase in pressure on the telescope that are mainly responsible for the decrease in drag.

The dimensioning of these deflectors, their position as well as the materials used are parameters which strongly influence the lift and the drag.

According to document US5374098, roof flaps are used to avoid the total loss of grip when the vehicle is in rotation. It is proposed to position two deflectors on the roof which are raised when the vacuum generated during the rotation phase becomes significant. These deflectors add aerodynamic support to the vehicle. This technology aims to improve driver safety when the driver has lost control of the vehicle.

But we are faced with a difficulty in using these systems in a concrete context of driving, where various driving assistance systems or driving monitoring exist, without integrating the possibility that the vehicle can carry shutters resembling self-adapting deflectors.

To solve this problem, a system for modifying the aerodynamic characteristics of a motor vehicle is proposed, comprising at least one flap defining an internal surface and an external surface of the flap, the flap being configured to increase the downforce of the vehicle, by being movable between at least one folded position in which the internal surface of the flap is placed against a trailing edge of the external surface of the vehicle and a deployed position as a function of air pressure on the external surface of the flap.

The system notably comprises an active control means to allow or block a passage between the folded position and the unfolded position as a function of instant information relating to the dynamics of the vehicle.

Optional and advantageous characteristics are stated as follows:

- the instant information is a numerical value and the control means allows or blocks the passage between the folded position and the unfolded position according to the comparison of a predetermined threshold and the instant information;

- the control means allows or blocks the passage between the folded position and the unfolded position by means of an electromagnetic, mechanical or hydraulic actuator;

- The instantaneous information relating to the vehicle dynamics includes brake control information, information relating to an anti-lock brake system, information relating to a programmed electrostabilizer system, relative information to an electrically controlled brake system, information relating to a hill start assist system, information relating to a braking boost system in an emergency, information relating to a regulation of the engine torque at deceleration, information relating to an automatic adaptation of the speed control, information relating to a collision anticipation system, information relating to a vehicle ride height, vehicle speed information, or a measurement of drag or vehicle lift;

- The control means is configured to allow passage into the deployed position in a vehicle skid situation, in an emergency braking situation or in a simple braking situation;

- the flap is installed on a roof, a spoiler, a window, a rear view mirror, or a side of the vehicle;

- the flap lifts in the direction of the air flow or in the opposite direction of the air flow when the vehicle moves forward;

- the flap comprises slots of square or beveled shape;

- The system further comprises a holding system which clamps below a maximum value the angle of deployment of the flap in the deployed position.

The invention also relates to a motor vehicle comprising a system for modifying the aerodynamic characteristics, in which instant information relating to the dynamics of the vehicle is provided by means of active control to assist the driving of the vehicle.

The invention will be better understood, and other objects, characteristics, details and advantages thereof will appear more clearly in the explanatory description which follows, made with reference to the appended drawings given solely by way of example illustrating a embodiment of the invention and in which:

- Figure 1 is a schematic view of an embodiment of the invention;

- Figure 2 is a view of a first embodiment of the invention;

- Figure 3 is a view of a second embodiment of the invention;

- Figure 4 is a view of a fourth embodiment of the invention;

- Figure 5 is a view of a variant of the mode of Figure 4;

- Figure 6 is a view of a fifth embodiment of the invention;

- Figure 7 is a view of a sixth embodiment of the invention;

- Figure 8 is a view of the embodiment of Figure 7, after opening the shutter;

- Figure 9 is a view of a seventh embodiment of the invention.

Referring to Figure 1, the invention consists of a self-adapting deflector 100 consisting of a flap defining an internal surface and an external surface of the flap, the flap being configured to increase the downforce of the vehicle, by being mobile between at least one folded position in which the internal surface of the flap is placed against a trailing edge of the external surface of the vehicle and a deployed position. The passage from one of the positions to the other is done according to an air pressure on the external surface of the shutter.

According to the invention the flap activates automatically thanks to the vacuum generated on the vehicle and lifts to act as a deflector. In this way, the air flow re-attaches to the deflector and allows, depending on the position, size and configuration of the deflector, to obtain an aerodynamic gain in terms of downforce, and an increase in the vehicle grip support to the ground, which improves safety. The deflector 100 can be replaced by self-adapting multi-deflectors.

According to the invention, the self-adapting deflector 100 is deployed as a function of the flow, the speed of the vehicle, the skidding of the vehicle, during emergency braking or braking. simple. This is authorized by a clamping or release means 110 which receives instantaneous information relating to the dynamics of the vehicle from an active control system 200.

The active control system 200 can be connected to a vehicle system such as the brake pedal, the ABS anti-lock brake system, the ESP programmed electrostabilizer system, the ECB electrically controlled brake system. , the HAC hill start assist system, the BAS emergency braking boost system, MSR deceleration of engine torque, ACC automatic speed control adaptation system, PCS collision anticipation system, a vehicle body height control system, a vehicle speed measurement system, or vehicle drag or lift measurement system, or any other type of system providing information on the actual situation of the vehicle.

For example, the active control system 200 is a body height sensor which makes it possible to prejudge the attitude of the vehicle, with a view to using the deflector 100 during a precise phase such as simple braking, emergency braking, or a skid condition, to increase the aerodynamic support, that is to say the downforce, of the vehicle and thus reinforce safety.

The control system 200 can be connected to the speed of the vehicle or to the aerodynamic state of the vehicle, assessed by one or the other of physical values such as the measurement of drag SCx, the measurement of lift SCz , or the pressure coefficient.

The instantaneous information obtained is in some of these cases a numerical value, and it can be compared with a predetermined threshold to know if the passage between the two positions is enabled or blocked.

The deflector 100 can be fixed by gluing or welding on a part of the vehicle known to be low pressure, such as, for example, the roof, a side edge, or the base of the vehicle.

The deflector 100 can be held by hinges, as shown in Figure 2 where we view a flap 1 on a rear spoiler of a motor vehicle. The self-adjusting deflector is placed on the spoiler of a vehicle fixed by hinges.

It can also be embedded directly in an element of the vehicle such as the end of the roof or the spoiler, as is the case in FIGS. 3 and 4, where we can see deflectors 2 and 3 fixed or else embedded on / in the spoiler. In Figure 3, the self-adapting deflector is flexible and fixed without hinge on the spoiler. In Figure 4, we see a self-adapting deflector 3 fixed, or integrated, directly on the bezel or on the end of the roof for two and a half and three-body vehicles. The deflector can be fixed with or without a hinge.

The deflector 100 can be fixed or integrated into the rear window of the vehicle. For this it is preferably composed of a transparent material, such as acrylic, polyvinylidene fluoride PVDF, or plexiglass.

The deflector 100 can be fixed or integrated on any other zone of the vehicle, such as the roof, the spoiler, the window, a rear-view mirror, a side part of the vehicle, if it is subject to a surface at a flow low pressure which allows the activation of the deflector.

The deflector 100 must have at least one degree of freedom. It can be lifted in the direction of flow, as in Figures 2 to 4 and 7 and 8 or in the opposite direction of flow as in Figures 6 and 9, which have reverse self-adjusting deflectors.

The deflector 100 must be an essentially passive element, the pivoting of which is triggered by the low pressure flow.

The deflector 100 can be made non-activatable by the clamping or release means 110, in which case the deflector 100 is forced to remain pressed against the vehicle. The deflector 100 can, conversely, be made activatable from a threshold value of information held by the control element 120.

The self-adaptive capacity of the deflector, that is to say its ability to deploy, can thus be restrained and activated if necessary by a control system. The latter may use, in the clamping or release means 110, a magnet, a mechanical means, or even a hydraulic means.

This control assembly comprising the control element 120 and the clamping or release means 110 keeps the deflector pressed against the vehicle, which has the consequence that the vehicle is in a configuration which optimizes aerodynamic drag, and releases it when its intervention is deemed necessary, during braking for example to increase the support, that is to say the downforce, or even in a skid situation to break the asymmetry of the flow and increase the aerodynamic support of the vehicle.

The self-adapting capacity of the deflector can be released or restrained depending on the state of the vehicle, but the deflector remains passive because it requires no energy input to deploy.

The deflector 100 may be a set of independent elements or may be in one piece with slots having a length which can range from 0.1% to 99% of the length of the deflector and a square or bevelled shape. This is seen in Figure 5, where there is shown a self-adapting deflector 4 fixed with or without hinge and having slots ranging from 0.1% to 100% of the length of the deflector.

As mentioned above, we can set up a multi-deflector: instead of having a single deflector over the entire length of the wing it is cut into small sections independent of each other. The result of these multi-deflectors is significantly different, the behavior of the lift as a function of the angle according to the position changes compared to the use of a simple deflector. The gain in lift is for the most part, depending on the configuration, better than with a simple deflector.

The deflector can be flexible or rigid, preferably light, for example less than 5 kg.

The deflector may be made of metal, such as aluminum, or a thin steel, of plastic, such as acrylic, plexiglass, or polyvinylidene fluoride PVDF, or of a composite material, such as fiberglass, or carbon fiber.

The deflector can be smooth, rough, porous, honeycomb, waterproof.

The deflector material can be reinforced using a rigid structure.

The dimensions of the deflector are of the order of 1 mm to 1000 mm in length in the direction of flow, 1% to 110% of the width of the vehicle for the span, and preferably more than 75%. , and 0.001 mm to 30 mm thick, preferably less than 2 mm.

The following parameters are proposed in particular: a position between 50% of the wing chord and the trailing edge, a size of at least 30% of the wing chord, a width of 80 % of the wing chord, materials offering a compromise between rigidity, thickness and density. A shape in small shears does not degrade the lift at low angles of attack.

The use of the self-adaptive multi-deflector or of a coating of the hairy coating type are alternatives which also make it possible to obtain an aerodynamic gain on the system studied. A deflector is positioned on an area of the vehicle prone to depression, generally in the range of -0.05 to -1.5 in dimensionless pressure coefficient. This zone can be for example the roof, the spoiler, the window, the lateral parts of the vehicle.

During passive or semi-active activation of such a deflector, the downforce, that is to say the aerodynamic support, increases in particular when the vehicle is in braking attitude. Wind tunnel measurements show gains equivalent to a 50 kg load on the rear axle.

The deflector 100 can remain pressed against the vehicle at low speeds, typically less than 60 km / h.

The deflector 100 is raised when the depression which is exerted on the deflector is sufficient to compensate for its weight.

When the deflector 100 is raised, the flow re-attaches along the deflector, any recirculations can be thus eliminated and the intensity of any longitudinal vortices reduced.

The self-adapting deflector 100 can make it possible to reduce the aerodynamic drag but above all makes it possible to reduce the lift, that is to say to increase the aerodynamic support, of the vehicle.

The deflector 100 may have a holding system which limits its angle of freedom to 90 °. This is shown in Figure 6, which shows the flange 6 which maintains the angle of freedom of the self-adjusting deflector within a limited range.

The deflector 100 can replace or act as an aerodynamic spoiler.

In Figures 7 and 8 there is shown the activation of a self-adapting deflector 7 embedded in a spoiler. In FIG. 7, the deflector is pressed against the vehicle, the drag is optimized. In Figure 8, the aerodynamic support is optimized, the deflector is left free and lifts when the speed is high and a depression tends to form above its surface.

In Figure 9, the deflector 100 is, as in Figures 7 and 8, embedded in the spoiler, but it is here reversed, as in Figure 6. It is equipped with a holding system 10 which clamps the angle freedom of the self-adjusting deflector, as in figure 6.

The deflector is illustrated essentially on the spoiler. The deflector can nevertheless be placed on various external surfaces of the vehicle, to exploit all the existing vacuum zones, including the entire roof, the bezel, the side parts, the base of the vehicle, the mirrors.

The interests of the invention are the gain in support, that is to say in downforce, for any type of attitude, a gain in grip and therefore better road holding, better stability during a braking attitude. , especially during emergency braking, which improves safety. The invention allows better stability of the vehicle when it is in a skid.

The gains in lift are maximum for a position close to the trailing edge, a length of between 10% and 40% of length of rope, materials rigid enough not to deform, light enough to be able to lift, by example of a surface density of less than 2.7 kg / m ² , and a part that is thin enough not to create a setback which would have aerodynamic repercussions. Thus, the thickness is preferably less than 2 mm.

There is also a potential gain in drag for any type of attitude, whether it is high, normal, suitable for performance and consumption, suitable for braking, implying a gain in carbon dioxide emission.

There is also an advantage in terms of vehicle silhouette style because the self-adapting deflector can replace visible and marked aerodynamic appendages. The system can be invisible at low speeds by being perfectly integrated into the original silhouette of the vehicle. This offers a distinctive character and therefore an advantage in attractiveness, in particular to allow hatchback silhouettes and half desired by the style.

The system is easy to integrate into existing elements, such as a spoiler, and it has the advantage of being essentially passive, since there is not, for example, a motorized system which would be heavy , fragile and expensive. The system is generally inexpensive, and lighter.

In the long term, the invention has an advantage in increasing aerodynamic support, by reducing lift, without penalizing drag, which makes it possible to improve the stability of the vehicle, and reduce drag and therefore decrease fuel consumption.

Claims (10)

1. A system for modifying the aerodynamic characteristics of a motor vehicle comprising at least one flap (100) defining an internal surface and an external surface of the flap, the flap (100) being configured to increase the downforce of the vehicle, by being mobile, depending on an air pressure on the external surface of the flap, at least one folded position in which the internal surface of the flap is placed against a trailing edge of the external surface of the vehicle and a deployed position, characterized in that that the system comprises an active control means (110) to allow or block a passage between the folded position and the unfolded position according to instant information (120) relating to the dynamics of the vehicle. 2. System for modifying the aerodynamic characteristics according to claim 1, characterized in that the instant information (120) is a numerical value and the control means (110) allows or blocks the passage between the folded position and the unfolded position in function of the comparison of a predetermined threshold and instant information. 3. System for modifying aerodynamic characteristics according to claim 1 or claim 2, characterized in that the control means (110) allows or blocks the passage between the folded position and the unfolded position by means of an electromagnetic actuator , mechanical or hydraulic. 4. System for modifying aerodynamic characteristics according to one of claims 1 to 3, characterized in that the instant information (120) relating to the dynamics of the vehicle comprises brake control information, information relating to a system of anti-lock brakes, information relating to a programmed electrostabilizer system, information relating to an electrically controlled brake system, information relating to a hill start assist system, information relating to a braking system amplification of braking in an emergency, information relating to a regulation of the engine torque during deceleration, information relating to an automatic adaptation of speed control, information relating to a collision anticipation system, relative information at vehicle height, vehicle speed information, or trail measurement born or lift of the vehicle. 5. System for modifying the aerodynamic characteristics according to one of claims 1 to 4, characterized in that the control means (110) is configured to allow passage into the deployed position in a vehicle skid situation, in a braking situation d 'emergency or simple braking situation. 6. System for modifying the aerodynamic characteristics according to one of claims 1 to 5, characterized in that the flap (110) is installed on a roof, a spoiler, a window, a rear view mirror, or a side of the vehicle. 7. System for modifying the aerodynamic characteristics according to one of claims 1 to 6, characterized in that the flap (110) lifts in the direction of the air flow or in the opposite direction to the flow of air when the vehicle is moving forward. 8. System for modifying aerodynamic characteristics according to one of claims 1 to 7, characterized in that the flap (110) comprises slots of square or bevelled shape. 9. System for modifying the aerodynamic characteristics according to one of claims 1 to 8, characterized in that it further comprises a holding system (6, 10) which clamps below a maximum value the angle of deployment of the shutter in the deployed position. 10. Motor vehicle comprising a system for modifying the aerodynamic characteristics according to one of claims 1 to 9, characterized in that instant information (120) relating to the vehicle dynamics is provided by active control means (110) for assist in driving the vehicle. ^ i ^ .7