Patent Application
20200156715
The invention relates to the field of motor vehicles, and more particularly aerodynamic devices arranged at the front of a vehicle to reduce the aerodynamic drag generated by this vehicle travelling at high speed.
One of the means used for many years to improve the aerodynamic efficiency of vehicles consists in reducing the underbody space between the road and the vehicle.
Since the vehicle ground clearance must remain at a height compatible with the use requirements, a satisfactory result can be obtained by lowering an aerodynamic barrier acting as deflector at the front part of the vehicle, and preferably arranged in front of the wheels.
This deflector can therefore be lowered or raised depending on the driving conditions such as the vehicle speed or road condition.
Publication U.S. Pat. No. 7,775,582 provides an example of this type of device.
However, other constraints must also be taken into account to implement these deflectors. We may mention for example the size of the device in the raised position in a reduced space located at the front of the vehicle, the mechanical strength to oppose the air pressure when the vehicle is travelling at high speed, the protection of the device and the deformability of the device in case of head-on impact, the possibility of folding away the device very quickly when an unplanned obstacle appears on the road, and the ease of repair in case of damage.
Lastly, an additional constraint is due to the style requirements inherent to this part of the vehicle, in which the aerodynamic device is visible from the outside and is an integral part of the bodywork. The aerodynamic deflector therefore has curved shapes designed to preserve the continuity of shape and style with the lower part of the bumper.
Numerous publications have proposed to solve all or some of the above-mentioned constraints.
For example, publication U.S. Pat. No. 7,775,582 already mentioned proposes a rigid system actuated by cable, which is difficult to operate and relatively bulky. This device also represents an obstacle to the deformability of the front part in case of head-on impact.
Publication U.S. Pat. No. 8,677,817 describes an inflatable aerodynamic deflector of reduced size and total deformability. However, this device has low resistance to air pressure when the vehicle is travelling at high speed, and requires the installation of a compressed air source inside the vehicle.
The device described in publication U.S. Pat. No. 8,702,152 consists of a vertically movable aerodynamic deflector. It is difficult to protect this device against the hazards of the road and it cannot be disengaged easily. In addition, in case of head-on impact, its rigid structure located at the very front of the vehicle is easily damaged and obstructs the deformation of the front block towards the rear of the vehicle. Similar devices are proposed by publications U.S. Pat. No. 4,951,994 or U.S. Pat. No. 7,686,382.
Publication U.S. Pat. No. 7,686,383 proposes to deploy a plurality of curved flaps arranged in the extension of the lower part of the bumper. This device offers the advantage of following the curve of the bumper, but its highly complex implementation is relatively incompatible with the robustness and cost requirements imposed by car manufacturers.
Publication U.S. Pat. No. 8,887,845 provides for separating the aerodynamic barrier into three separate flaps pivoting on flexible and curved axes. This results in significant driving forces to compensate for the transmission losses.
The device described in publication U.S. Pat. No. 4,659,130 remains bulky and is difficult to fold away quickly if an obstacle is encountered on the road.
Although all these devices can reduce the amount of air flowing under the vehicle, none of them solves all the above-mentioned constraints.
The aerodynamic deflector according to the invention is characterised in that it comprises a deformable skin of which an upper strip is rigidly connected to the lower portion of a front bumper, and of which a lower strip is connected to a front edge of a rigid arch that can be moved by a manoeuvring device between a low position in which the deformable skin is deployed so as to divert the flow of air that presents under the vehicle when the vehicle advances, and a high position in which the deformable skin is folded away in a recess arranged behind the bumper.
Due to the flexibility of the skin and its ability to deform, the skin can now be folded away or deployed while avoiding the constraints related to the pronounced curve of the lower profile of the bumper, and deformable skin can be placed in front of the vehicle wheels across the entire width of the bumper. The deformable skin therefore comes in continuity of shape with the general shape of the front bumper and follows the lower curve of the bumper from one end of the bumper to the other.
As we will see below, this advantage also offers the possibility of proposing a compact and lightweight manoeuvring device allowing the deformable skin to fold away on itself and undergo controlled deformations, to enter the recess provided for this purpose behind the bumper, or to deploy completely to deflect the flow of air passing under the vehicle.
The device according to the invention may also comprise, taken alone or in combination, the following characteristics:
The invention will be better understood on reading the accompanying figures, which are given solely by way of example and not limiting in any way, in which:
In the remainder of the document, longitudinal direction means the direction X′OX going from the rear to the front of the vehicle, transverse direction means the direction Y′OY parallel to the wheel axes, and vertical direction means the direction Z′OZ perpendicular to the plane on which the vehicle moves.
The deformable skin 4 is connected by its upper strip 40 to the lower edge of the front bumper 31, and by its lower strip 41 to a rigid arch 2, shown on
In this low position, the lower strip 41 of the deformable skin and the rigid arch 2 are positioned at a relatively constant height from the ground.
The manoeuvring device 1 used to deploy or retract the deformable skin on which this description is based is shown in detail on
The rigid arch 2 has a front edge 21 to which the lower strip 41 of the deformable skin 4 is attached.
For purposes of impact resistance, vibratory rigidity and lightness, the rigid arch 2 may advantageously be made of a composite or thermoplastic material.
The rigid arch 2 is connected to the vehicle chassis by two rear connecting rods 11 and 12 and by one front connecting rod 13.
The front connecting rod 13 comprises a first end connected to the vehicle chassis by a first hinge 130 of axis dd′, and a second end connected to the rigid arch by a second hinge 131 of axis cc′.
The rear connecting rods 11 and 12 comprise a first end connected to the vehicle chassis by a first hinge, respectively 110 and 120, of axis aa′, and a second end connected to the rigid arch 2 by a second hinge, respectively 111 and 121, of axis bb′. The second hinges of the rear and front connecting rods are attached to the rigid arch 2 by base plates, respectively 112, 122 and 132.
The axes aa′, bb′, cc′ and dd′ are parallel to each other and to the transverse direction OY of the vehicle and arranged so that the projections A, B, C, D, of the axes aa′, bb′, cc′ and dd′ on a plane P perpendicular to said axes define the four vertices of a deformable right parallelogram. The axis aa′ is offset from the axis dd′, in the longitudinal direction towards the rear of the vehicle, by a non-zero constant distance d equal to the constant distance between the axes bb′ and cc′. The constant distance between the axes aa′ and bb′ or between the axes cc′ and dd′ is equal to h.
The number of front connecting rods and rear connecting rods is not limited to the number given in this description. Thus, it is quite possible to consider multiple combinations in which there are a single rear connecting rod and a single front connecting rod, or a single rear connecting rod and two front connecting rods or, for greater rigidity, two rear connecting rods and two front connecting rods. However, due to the pronounced curve of the rigid arch 2, the front connecting rods are preferably positioned near the centre of the rigid arch, defined here as being the line of intersection of the vehicle longitudinal plane of symmetry OXZ with the rigid arch, and arranged at equal distances from the two lateral ends of the rigid arch.
In all these configurations, the first ends of the rear connecting rods are connected to the vehicle chassis by first hinges of axis aa′, and the second ends of the rear connecting rods are connected to the rigid arch 2 by second hinges of axis bb′. Similarly, the first ends of the front connecting rods are connected to the vehicle chassis by first hinges of axis dd′, and the second ends of the front connecting rods are connected to the rigid arch 2 by second hinges of axis cc′.
In the device on which this description is based, the first ends of the rear connecting rods 11 and 12 are attached to an actuation shaft 10 of axis aa′ connected to the chassis by bearings 100 and 101, shown on
This arrangement, in which the actuation shaft is placed as far back as possible, allows better deformation of the front part of the vehicle in case of head-on impact. In addition, the actuator and the rear connecting rods, which are expensive to replace, are better protected by being located as far away as possible from the impact areas on the bumper.
The first hinge 130 of the front connecting rod can rotate freely about the axis dd′, and the second hinges, respectively 111, 121, 131 connecting the rear connecting rods and the front connecting rod to the rigid arch can rotate freely about their respective axes, bb′ and cc′.
By rotating a quarter turn about the axis aa′, the actuation shaft 10 pivots the rear connecting rods 11 and 12 and moves the rigid arch from the low position in which the connecting rods are substantially oriented along the vertical axis to the high position in which the connecting rods are substantially oriented along the longitudinal axis. During this movement, the rigid arch moves in translation from the front to the rear of the vehicle.
The front connecting rod is moved by the displacement of the rear connecting rods and the rigid arch. The parallelogram formed by the front and rear connecting rods deforms about the fixed axes aa′ and dd′. Points B and C move in the plane P to B′ and C′.
We see that during this movement, the plane formed by the axis bb′ and cc′, which can be assimilated to the plane of the rigid arch 2, remains substantially parallel to the plane formed by the ground on which the vehicle travels.
In the device on which the description of the invention is based, the actuation shaft is a rotating shaft of axis aa′ driving in rotation the rear connecting rods 11 and 12. We see that it is also possible to position the actuation shaft on the axis dd′ to drive the front connecting rod. Or to rotate one of the connecting rods using a secondary shaft moving along a substantially linear path.
In all the above-mentioned arrangements, care must be taken to ensure that the actuator, or more generally the means for driving in rotation the front and rear connecting rods, can be disengaged under the effect of an abnormal mechanical stress. When the vehicle is moving and the rigid arch is placed in the low position, the vehicle ground clearance is lowered, and the rigid arch could in fact hit an obstacle placed on the road. The integrity of the rigid arch, the deformable skin, and more generally of the connecting rods forming the manoeuvring device, must therefore be preserved.
Thus, the actuator 5 comprises a torque limiter whose threshold is adjusted so that, when the vehicle is moving and the rigid arch hits an obstacle, the actuator is disengaged and the rigid arch moves from the low position to the high position by moving from the front to the rear, under the effect of the momentum acquired during the impact between said rigid arch 2 and said obstacle. The lighter the rigid arch the smaller the momentum and the lower the damage due to the impact between the rigid arch and the obstacle.
Advantageously, the manoeuvring device may comprise additional drive elements for transmitting the driving force generated by the actuation axis 10 to the front connecting rod 13 so as to avoid transmitting excessive forces in the rods.
The manoeuvring device 1 comprises a return connecting rod 15 parallel to a plane passing through the axes aa′ and dd′, which is connected by one of its ends to the front connecting rod 13 by a hinge 150 of axis ff′ parallel to the axis aa′, and by its other end to a secondary driving connecting rod 14 by a hinge 141 of axis ee′ parallel to the axis aa′. The secondary driving connecting rod 14 is parallel to the front connecting rod 13, and comprises another end 140 attached to the actuation shaft 10.
The projection of axes aa′, ee′, ff′ and dd′ on the plane P forms the four vertices A, E, F, D of a deformable parallelogram. The constant distance between the axes aa′ and ee′ or between the axes dd′ and ff′ is equal to h′, and the constant distance between the axes ee′ and ff′, which is the same as that between the axes aa′ and dd′, is equal to d. When the manoeuvring device is moving, the points E and F move to E′ and F′.
The secondary driving connecting rod 14 and the return connecting rod 15 thus transmit some of the torque from the actuation shaft 10 to the front connecting rod 13, so as to reduce the transmission forces in the hinges located between the rear connecting rods 111 and 121 and the rigid arch 2, and avoid the irreversible deformation of the parallelogram formed by the axes aa′, bb′, cc′ and dd′.
Obviously, when the actuation shaft is arranged on the axis dd′ to which the first hinges of the front connecting rods are attached, the secondary driving connecting rod is then connected to the front actuation shaft and the return connecting rod to a rear connecting rod.
The rear connecting rods 11 and 12 and the front connecting rod are arranged in the high position.
Configured in this way, the aerodynamic deflector can meet most of the design constraints mentioned in the introduction to this description.
In particular, it offers sufficient resistance to the aerodynamic force exerted on the skin in the low deployed position, a possibility of folding away quickly when an unplanned obstacle appears on the road, reduced size in the high folded position, and ease of repair in case of head-on impact. Lastly, the deformable skin may have an outer profile in perfect continuity of shape and style with the vehicle bumper so that it can be deployed over a substantially constant height across the entire width of the vehicle, and in particular in front of the wheels.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1663000 | Dec 2016 | FR | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/FR2017/053485 | 12/11/2017 | WO | 00 |
