WO2011070259A1

WO2011070259A1 - Flexible aerodynamic device

Info

Publication number: WO2011070259A1
Application number: PCT/FR2010/052386
Authority: WO
Inventors: Patrick Perot; Philippe Perreux
Original assignee: Renault Sas
Priority date: 2009-12-10
Filing date: 2010-11-05
Publication date: 2011-06-16
Also published as: FR2953798B1; FR2953798A1; EP2509851B1; EP2509851A1

Abstract

The invention relates to an aerodynamic device which is intended to be installed at the front of a motor vehicle. Said motor vehicle comprises a chassis element (22) and a front apron (20) having a lower free edge (26) which is curved towards said chassis element and at a distance from said chassis element. Said aerodynamic device comprises a skirt (34) having a profiled upper part (32) that is able to be pressed against said lower free edge (26). Said aerodynamic device comprises a flexible retaining plate (36) which is integral with said profiled upper part (32) and which extends perpendicularly to said skirt in order to be connected to said chassis element (22) in a linking region (37) so as to keep said skirt (34) in line with said front apron (20). Said flexible retaining plate (36) is able to bend around said linking region (37) in order to enable said skirt (34) to move in a direction parallel to the generatrices of said skirt (34).

Description

Flexible aerodynamic device

The present invention relates to flexible aerodynamic devices for motor vehicles to reduce the lift of moving vehicles.

Motor vehicles in motion tend to lose their grip on the ground and especially on the roads as their speed increases. Indeed, as the speed increases the air tends in particular to rush under the vehicle and to print an upward vertical force that decreases the adhesion of the vehicle wheels on the ground. Such a phenomenon can lead to a loss of control of the vehicle and to a road exit. To reduce this lift, it has been imagined to reduce the ground clearance of the vehicle, that is to say, to minimize the distance between the chassis of the vehicle and the ground. However, such a reduction is possible only if the ground is perfectly smooth and if it does not present sudden variations of inclination. However, the motor vehicle is often required to cross obstacles, for example sidewalks or crevices of the ground, so that the ground clearance can not be reduced below a certain threshold.

It was then imagined to adjust a flexible skirt below the front bumper of motor vehicles so as, firstly reduce the amount of air able to rush under the vehicle and, secondly to allow the vehicle to ride on uneven ground. Indeed, thanks to its flexibility, as soon as the skirt meets an obstacle, it deforms to fade before him and then resumes its normal position as soon as the obstacle is crossed. Reference can be made to Japanese document JP2008307938, which discloses the implementation of such a flexible skirt under the front bumper of a motor vehicle.

However, the flexible skirt pivots easily when a substantially perpendicular stress is applied thereto, and this is the case when an obstacle is encountered on the ground, while the vehicle is moving in a substantially rectilinear path and parallel to the ground . On the other hand, when the skirt undergoes a stress substantially perpendicular to the chassis of the vehicle, this may be the case when the vehicle crosses a low sidewalk. speed, this constraint can be reflected in the shield and cause damage. Naturally, to answer this problem, the motor vehicle manufacturers have reinforced both the shield and the connection with the skirt. However, the costs of such reinforcement are significant.

Also, a problem that arises and that aims to solve the present invention is to provide an aerodynamic device including a skirt that not only allows to cross certain obstacles without causing damage to the front bumper of the vehicle, but also that can be produced at an advantageous cost.

In order to solve this problem, the present invention proposes a flexible aerodynamic device intended to be installed at the front of a motor vehicle. Said motor vehicle comprises a frame member and a shield mounted at the front of said motor vehicle substantially perpendicularly to said frame member, said shield having a lower free edge curved towards said frame member. Said lower free edge extends away from said frame member and said aerodynamic device comprises a skirt defining a cylindrical surface, said skirt having a profiled upper portion adapted to be applied against said lower free edge of said shield, while said skirt extends in the extension of said shield. Said skirt is adapted to be pivotally driven towards said frame member when it undergoes a stress substantially perpendicular to said skirt. According to the invention the aerodynamic device further comprises a flexible holding plate integral with said profiled upper portion of said skirt and extending substantially perpendicular to said skirt, said flexible holding plate being able to be connected to said frame member in a connecting zone so as to maintain said skirt in the extension of said shield. And, said flexible holding plate is able to bend around said connection zone to allow the movement of said skirt in a direction substantially parallel to the generatrices of said cylindrical surface of said skirt, of so as to allow the retraction of said skirt behind said shield when said skirt undergoes a stress substantially parallel to said generatrices.

Thus, a feature of the invention lies in the implementation of a skirt integral with the frame member through the holding plate and which is independent of the shield. In this way, when the skirt undergoes a vertical stress, or perpendicular to said frame member of the motor vehicle, and in a direction directed towards the shield, it does not undergo any effort because the skirt retracts precisely behind the shield, in a direction substantially parallel to the generatrices of the cylindrical surface of the skirt, while the flexible holding plate flexes. As will be explained in more detail in the following description, the skirt extends along the shield which itself extends over the entire width of the front portion of the vehicle. Also, the skirt is capable of retracting precisely in a determined part of the width while the other parts remain intact. Accordingly, the holding plate flexes substantially in an area corresponding to said determined portion of skirt. In addition, the holding plate is elastically deformable so that, when the vertical stresses on the skirt cease, the holding plate tends to return to its original shape and the skirt resume its position in the extension of the shield.

According to a particularly advantageous embodiment of the invention, and which allows the skirt to pivot, the aerodynamic device further comprises support members secured to said profiled upper skirt portion and which extend to the skirt. opposite said skirt, and said support members bear against said shield when said skirt and said support members are driven together pivotally to said frame member, while said flexible support plate flexed between said shaped upper portion of skirt and said connection zone. In this way, the skirt is not rotated either around the profiled upper part but at the level of the support members which makes it possible to obtain a greater radius of pivoting curvature of the skirt. Moreover, it is the holding plate which flexes between the profiled upper part and the connection zone when the skirt pivots. By therefore, the profiled upper part around which the skirt pivots in the devices of the prior art, is no longer mechanically solicited for the object of the present invention. It is indeed this profiled upper part that bears against the lower free edge of the shield to ensure airtightness and should be preserved.

In addition, preferably, said support members extend substantially parallel to said generatrices of the cylindrical surface of the skirt. The support members and the skirt then form a rigid assembly, so that, when the skirt is subjected to a perpendicular stress, it pivots with the supporting members which extends it, and when the skirt undergoes a stress substantially parallel to the generatrices, the skirt and the support members are driven in translation in a direction substantially coincident with the generatrices.

Advantageously, said support members comprise tabs terminated respectively by a free hook. And they are spaced step by step over the entire length of the aerodynamic device. In addition, the free hook is intended to bear on a bearing surface formed in the shield so as to lock the skirt in translation in a direction parallel to the generatrices, but oriented towards the ground. Thus, the skirt can pivot towards the frame member with the support member around the bearing surface where the free hook is engaged.

Furthermore, said flexible holding plate comprises a fastening edge opposite said profiled upper skirt portion and intended to be connected to said frame member in said connecting zone. Thus, when the skirt is driven in translation along its generatrices to be retracted behind the shield, the flexible holding plate in the fastening edge is engaged at the binding zone flexed flapping around this connection zone. On the other hand, when the skirt pivots with the support member, the holding plate undergoes stresses where the profiled upper part is driven towards the connection zone, which causes a deflection of the holding plate which then curves. approaching said frame member. Of course, the holding plate being deformable elastically, when the forces exerted on the skirt to rotate it cease, then the holding plate returns to its original shape and the skirt its position in the extension of the shield where the profiled upper portion is applied against the lower free edge of the shield.

According to a preferred embodiment of the invention, said attachment edge is raised relative to said flexible holding plate in a direction opposite to said skirt, so as to move the flexible support plate of the frame member to allow him an amplitude of movement in sufficient beat. Advantageously, the aerodynamic device comprises a lip which protrudes from said profiled upper part of said skirt in a direction opposite to said holding plate, and which is intended to be applied against the lower free edge of the shield so as to waterproof. In this way, the air flows along the shield and then the skirt without penetrating under the frame element between the shield and the skirt. The aerodynamic device is thus more efficient. Moreover, said lip is curved in a direction opposite to said skirt. In this way, it comes to apply perfectly against the inside of the lower free edge of the shield which itself is advantageously curved.

In addition, the aerodynamic device extends in an arc and has two parts symmetrical to each other with respect to a median plane so as to be applied over the entire width of the front bumper of the motor vehicle. Thus, the device extends in arc from a front wheel to the other front wheel, and limits the air intake under the vehicle between these two wheels.

In addition, said skirt, said profiled upper portion, said flexible holding plate, said support members and said lip are advantageously molded together in one piece. This makes it possible to obtain an aerodynamic device at a very advantageous cost.

Other features and advantages of the invention will emerge on reading the following description of a particular embodiment of the invention, given by way of indication but not limitation, with reference to the accompanying drawings in which: - Figure 1 is a schematic perspective view of an aerodynamic device according to the invention;

FIG. 2 is a diagrammatic cross-sectional view of the aerodynamic device represented in FIG. 1 along plane 11-1 and associated with other elements of a motor vehicle;

3 is a schematic cross-sectional view of the aerodynamic device shown in FIG. 1 along the plane associated with the other elements of the motor vehicle; and,

- Figure 4 is a schematic cross-sectional view of an aerodynamic device according to the invention according to another embodiment.

Figure 1 shows in perspective an aerodynamic device 10 according to the invention intended to be installed in the front of a motor vehicle under the shield of the vehicle. The shield usually designates a large bumper that is intended to protect the body of the vehicle shocks occurring at low speeds. The shield is contoured and extends over the full width of the body, at the front of the vehicle so as to promote the best possible flow of air when the vehicle is moving.

The aerodynamic device 10 is adapted to be connected to the shield as will be explained below, and it extends in an arc between two opposite ends 12, 14. Moreover, it has two opposite parts 16, 18 symmetrical l one from the other with respect to a median plane P.

Referring to Figure 2, in which the aerodynamic device 10 seen in cross section is arranged with elements of a motor vehicle. These elements comprise a shield 20 having a free front surface 21 and a frame member 22 having a bottom wall 24. The shield 20 extends substantially perpendicularly to the frame member 22. Also, in the rolling situation of the vehicle, the air flows to the free front surface 21 of the shield 20.

The shield 20 has a lower free edge 26 curved towards the frame member 22. In addition, according to the embodiment shown in FIG. 2, it consists of two superposed profiled elements, the upper one 28, the other lower 30. These two profiled elements 28, 30 present respectively a lower flange 29 and an upper flange 31 curved flat and supported on one another. These flanges 29, 31 extend substantially to the right of the lower free edge 26 curved towards the frame member.

Regarding the aerodynamic device 10 in straight section, it is shown here in solid lines in its rest position, and in broken lines in an active position. It comprises an inverted T-shaped upper part 32 and a skirt 34. The inverted T-shaped upper part 32 has on the one hand a return 33 with respect to the skirt 34, oriented towards the lower free edge 26 and corresponding to the T bar, and secondly a rib 35 oriented away from the skirt 34, substantially offset towards the lower free edge 26 and corresponding to the leg of T. The skirt 34 defines a cylindrical surface Se which appears clearly on 1, and which is defined by generatrices G. In Figure 2, the aerodynamic device 10 further comprises a flexible holding plate 36 which extends substantially perpendicular to the skirt 34 and opposite the return 33. And opposite the holding plate 36, it further comprises a lip 38 which protrudes from the profiled upper portion 32 in the extension of the return 33 and is curved in a direction opposite to the skirt 34 . In C In this rest position, the lip 38 bears against the inner surface of the curved lower free edge 26 of the shield 20. On the opposite side, the holding plate 36 has a fixing edge 39 raised with respect to the middle plane of the plate. 36. The holding plate 36 is connected to the fixing edge 39 via a connecting edge 41. This connecting edge forms an angle close to 120 ° with both the holding plate 36 and the fixing edge 39. The fixing edge 39 is installed in a fixed position against the bottom wall 24 of the frame member. 22 in a connection zone 37.

In addition, the aerodynamic device 10 has a support member 40 consisting of a tab terminated by a hook 42, which extends from the profiled upper portion 32 parallel to the generatrices G and in a direction opposite to the skirt 34. The lug of the support member 40 extends for example over a length greater than the length of the skirt 34 in the direction of its generatrices, for example one and a half times greater as shown in FIG. Figure 2. In addition, the leg of the support member which extends substantially in the extension of the skirt 34 is with it a relatively rigid assembly in the direction of generators G and little subject to buckling. It will be observed in FIG. 1 that the lugs of the support members 40 are spaced substantially regularly from each other on the aerodynamic device 10 from one opposite end 12 to the other opposite end 14. The hook 42 has a shoulder 44 oriented towards the profiled upper part 32 and able to bear against the lower rim 29 of the upper profiled element 28.

Thus, in the rest position of the aerodynamic device 10, the skirt 34 is held in the extension of the shield 20 in a relatively tight manner thanks to the lip 28 which matches the shape of the inner surface of the lower free edge 26. Also, the skirt 34 is an aerodynamic wall that is intended to extend in the vicinity of the ground surface when the vehicle is supported on the ground and on its four wheels. Thanks to this aerodynamic wall the coefficient of penetration into the air of the moving vehicle, in correspondence with the Scx, is improved and consequently, the fuel consumption of the vehicle decreases. Therefore, the CO _{2 release} of the vehicle is less at equal speed.

Furthermore, the aerodynamic device 10 is made in one piece of plastic material, for example by means of an injection press. The chosen polymeric material is elastically deformable.

With this feature, the skirt 34 is pivotable when it undergoes a perpendicular stress oriented from the front to the rear of the vehicle. This is particularly the case when in rolling situation, an asperity is present on the ground. The skirt 34 thus undergoes a local stress substantially perpendicular to itself according to the arrow F. Also, when such a stress appears, the skirt 34 tends to pivot with the leg of the support member 40 which prolongs it in turn. closer to the frame member 22. The hook 42 indeed bears against the lower rim 29 and the lug of the support member 40 pivots with the skirt 34 which it rigidly extends, and this, around the hook 42. In doing so, the profiled upper portion 32 is driven to the connection zone 37 so that the holding plate 36 is bent towards the frame member 22 between the fixing edge 39 which is held in a fixed position and precisely the profiled upper portion 32. holding 36 flexes elastically, so that when the obstacle or roughness is crossed, the skirt 34 returns to its original position.

It will first be observed that the impact on the skirt 34 may occur over a more or less wide area and for example at a level located between two legs of consecutive support members 40, as illustrated in FIG. 1. Also, the skirt 34 then pivots, in the manner as indicated above, while the hooks 42 of the two consecutive tabs 40 are biased. Then, when the holding plate 36 flexes, this deflection occurs over a certain width of holding plate 36, located opposite the impact on the skirt 34. Moreover, the width of the deflection, where the holding plate 36 is curved, is substantially greater than the width of the impact zone on the skirt 34.

Note also that the radius of curvature corresponding to the movement of the free end of the skirt 34 during its pivoting is greater than that which would have the free end of a skirt which would pivot at the level of the profiled upper portion 32, as is the case for aerodynamic devices according to the prior art.

Referring now to Figure 3 showing the aerodynamic device in straight section, no longer at the leg of a support member 40, but precisely between two legs of support members 40 as shown in FIG. Figure 1 and in addition. In addition, this Figure illustrates a different mode of operation of the flexible aerodynamic device according to the invention compared to that which is exposed with regard to Figure 2.

Thus, we find in this Figure all the elements already described with reference to Figure 2 except the leg of the support member 40. The rest position of the aerodynamic device 10 is similar to that of the device shown in Figure 2 On the other hand, it is represented in broken lines in a different position where the skirt 34 has been driven into translation along an upward vertical direction, corresponding to the direction of the generatrices G.

Indeed, when the motor vehicle is for example parked on a sidewalk and it rolls to leave this parking position, when crossing the sidewalk, the skirt 34 is likely to undergo an upward vertical stress, where the lower edge of the skirt 34 falls back on the edge of the sidewalk. In this case, the skirt is driven in translation behind the shield 20 while the holding plate 36 bent towards the frame member 22 and the lip 38 leaves the inner surface of the lower free edge 26 on which it is based to be driven to the upper rim 31 of the lower profile member 30. Thus, the holding plate 36 tends to pivot about the connection area 37 and be driven towards the frame member 22. The width of the support plate 37 36, between the profiled upper portion 32 and the connecting edge 41 is greater than the length of the skirt 34, for example two times greater, so that the pivoting of the holding plate 36, leads to an average stroke of the skirt 34 substantially rectilinear. Moreover, the holding plate 36 tends to pivot around the connecting edge 41.

Thus, the skirt 34 retracts behind the shield 20 during the crossing of the obstacle or the sidewalk, and then as soon as the vehicle finds a relatively flat surface, the skirt 34 returns to its position corresponding to the rest position of the aerodynamic device, since the holding plate 36 has elastically deformed beforehand. Thus, when the vehicle returns to a usual rolling situation, the skirt 34 plays its role of aerodynamic wall.

It will be observed that the skirt 34 retracts vertically without causing damage to the shield 20 unlike the aerodynamic device according to the prior art.

According to another embodiment of the invention shown in FIG. 4, on which are found elements identical to those of the previous implementation mode with the same reference assigned a prime sign: "'" the device aerodynamic 10 'has two distinct parts; a skirt 34 'made of a more flexible material than a holding plate 36'. The skirt 34 'is L-shaped and thus has a fastening back 50 applied against the holding plate 36' on which it is riveted by means of a rivet "pop" 52.

Unlike the previous embodiment, the aerodynamic device 10 'does not include a support member of the aforementioned type. On the other hand, the skirt 34 'is made for example of a polyurethane-type plastic material, and consequently when it is struck by an obstacle in a perpendicular direction, it is deformed and tends to bend towards the holding plate 36 .

In addition, as in the previous embodiment, the skirt 34 'retracts vertically during the crossing of the sidewalk and then returns to its position corresponding to the rest position through the holding plate 36' which s is elastically deformed beforehand.

Claims

1. A flexible aerodynamic device (10) for installation at the front of a motor vehicle, said motor vehicle comprising a frame member (22) and a shield (20) mounted in front of said motor vehicle substantially perpendicularly to said motor vehicle member. frame, said shield having a lower free edge (26) curved toward said frame member, said lower free edge extending away from said frame member, said aerodynamic device (10) including a skirt (34) defining a cylindrical surface, said skirt having a profiled upper portion (32) adapted to be applied against said lower free edge (26) of said shield (20), while said skirt (34) extends in the extension of said shield, said skirt (34) being adapted to be pivotally driven to said frame member (22) when stressed substantially perpendicular to said skirt (34);

characterized in that it further comprises a flexible holding plate (36) integral with said profiled upper portion (32) of said skirt (34) and which extends substantially perpendicular to said skirt, said holding plate (36) flexible being adapted to be connected to said frame member (22) in a connecting zone (37) so as to maintain said skirt (34) in the extension of said shield (20);

and in that said flexible holding plate (36) is able to flex around said connection zone (37) to allow the movement of said skirt (34) in a direction substantially parallel to the generatrices G of said cylindrical surface of said skirt (34), so as to allow the retraction of said skirt (34) behind said shield (20) when said skirt (34) undergoes a stress substantially parallel to said generatrices G.

2. aerodynamic device according to claim 1, characterized in that it further comprises support members (40) integral with said profiled upper portion (32) skirt and which extend opposite said skirt ( 34), and in that said support members (40) bear against said shield (20) when said skirt (34) and said support members (40) are pivotally driven together to said frame member (22). ), while flexible holding plate (36) flexed between said profiled upper skirt portion and said connecting region (37).

3. Aerodynamic device according to claim 2, characterized in that said support members (40) extend substantially parallel to said generatrices G.

4. An aerodynamic device according to claim 2 or 3, characterized in that said support members (40) comprise tabs respectively terminated by a free hook (42).

Aerodynamic device according to any one of claims 1 to 4, characterized in that said flexible holding plate (36) comprises a fastening edge (39) opposite said profiled upper portion (32) of skirt and intended to be connected to said frame member (22) in said connection area (37).

Aerodynamic device according to claim 5, characterized in that said fixing edge (39) is raised relative to said flexible holding plate (36) in a direction opposite to said skirt (34).

Aerodynamic device according to any one of claims 1 to 6, characterized in that it comprises a lip (38) projecting from said profiled upper portion (32) of said skirt (34) in a direction opposite said holding plate (36).

8. aerodynamic device according to claim 7, characterized in that said lip (38) is curved in a direction opposite to said skirt (34).

9. Aerodynamic device according to any one of claims 1 to 8, characterized in that it extends in an arc and has two parts (16, 18) symmetrical to each other with respect to a median plane P .

Aerodynamic device according to any one of claims 1 to 9, characterized in that said skirt (34), said profiled upper portion (32), said flexible holding plate (36), said support members (40). and said lip (38) is molded together in one piece.