Air guiding device for a motor vehicle

Air guiding device (12) of a motor vehicle has an air guiding element (13) extending in the region of a forward structure part (11) of the motor vehicle completely or partially over the width thereof. An actuating element (16) can displace the air guiding element (13) between an extended operating position in which the air guiding element (13) has an aerodynamic air guiding effect, and a retracted inoperative position in which the air guiding element (13) has substantially no aerodynamic air guiding effect. The air guiding element (13) is formed at least in certain portions from an elastically deformable sheet-like element (15) whose outer contour can be brought into shape in such a way that the sheet-like element (15) ensures laminar flow guidance.

CROSS REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 to German Patent Appl. No. 10 2014 104 156.9 filed on Mar. 26, 2014, the entire disclosure of which is incorporated herein by reference.

BACKGROUND

1. Field of the Invention

The invention relates to an air guiding device for a motor vehicle.

2. Description of the Related Art

DE 103 25 653 A1 discloses an air guiding device of a motor vehicle that has a spoiler lip extending in the region of a forward structure part of the motor vehicle completely or partially over the width of the forward structure part. A pneumatic actuating element can displace the spoiler lip between an extended operating position and a retracted inoperative position. In the extended operating position, the spoiler lip forms a downwardly directed extension of the forward structure part and acts as an aerodynamic air guiding device. In the retracted inoperative position, the spoiler lip is directed rearwardly and has substantially no aerodynamic air guiding effect.

Air guiding devices for a motor vehicle with a pneumatic actuating element for a spoiler lip also are known from DE 10 2011 111 456 A1 and DE 10 2006 060 672 A1.

DE 36 30 645 A1 discloses another air guiding device for a motor vehicle.

The object of the invention is to provide a novel air guiding device for a motor vehicle.

SUMMARY OF THE INVENTION

The invention relates to air guiding element formed at least in certain portions from an elastically deformable sheet-like element whose outer contour can be brought into shape in such a way that the sheet-like element serves for laminar flow guidance or the outer contour thereof ensures laminar flow guidance.

The air guiding device of the invention achieves laminar contact between the flow and the air guiding element in the extended operating position and hence allows particularly advantageous flow guidance. As a result, the effectiveness of aerodynamically acting geometrical features that are positioned behind the air guiding device, such as diffusers, can be improved.

At least one elastic tension band may act on the sheet-like element to achieve the desired contour in the operating position of the air guiding element. As a result, a particularly reliable and dimensionally secure geometry can be ensured.

The air guiding element may be formed by a spoiler lip and by the elastically deformable sheet-like element. In the operating position, the spoiler lip forms a downwardly directed extension of the forward structure part and is directed rearwardly in the inoperative position. The elastically deformable sheet-like element adjoins behind the spoiler lip and below the forward structure part in such a way that the elastically deformable sheet-like element acts with a front portion on a lower portion of the spoiler lip in the operating position and on rear portion of the spoiler lip in the inoperative position and with a rear portion on the forward structure part.

The elastically deformable sheet-like element ensures that, in the operating position, the flow downstream of the spoiler lip comes into laminar contact with the sheet-like element so that subassemblies, such as diffusers, positioned downstream of the air guiding device can be subjected to improved flow.

The at least one elastic tension band acts on the sheet-like element and can bring the sheet-like element into a shape where the front portion is curved convexly down and out and at the rear portion curved concavely up and in. Each elastic tension band acts on a central portion of the sheet-like element in which the curvature thereof changes. Thus, it is advantageously possible to transfer the elastic sheet-like element into the desired curvature and to hold it in the desired curvature.

The air guiding element may be formed completely by the elastically deformable sheet-like element. More particularly, the elastically deformable sheet-like element may act with a front portion on a front portion of the forward structure part and with a rear portion on a rear portion of the forward structure part. Thus, the desired shapes for laminar flow guidance may be achieved merely the elastically deformable sheet-like element and without a spoiler lip.

The actuating element may have air chambers and acts on a portion of the elastically deformable sheet-like element and on a fastening strip for the actuating element. Optionally, at least one elastic tension band may act on a portion of the sheet-like element that is situated behind the portion on which the actuating element acts. Thus, a particularly advantageous shaping for the elastically deformable sheet-like element in the extended operating position of the air guiding device is possible.

Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIGS. 1 and 2show a detail of a front portion10of a motor vehicle in the region of a forward structure part11that forms a front end of the front portion10of the motor vehicle.

An air guiding device12is positioned in the region of the forward structure part11and extends completely or partially over the width of the forward structure part11. The air guiding device12comprises an air guiding element13, which, in the embodiment ofFIGS. 1 and 2, is formed by a spoiler lip14and an elastically deformable sheet-like element15.

The air guiding element13can be displaced with the aid of an actuating element16between an extended operating position (seeFIG. 2) and a retracted inoperative position (seeFIG. 1). The air guiding element13has an aerodynamic air guiding effect in the extended operating position, but has substantially no aerodynamic air guiding effect in the retracted inoperative position.

The actuating element16ofFIGS. 1 and 2is a pneumatic actuating element with a plurality of air chambers17. More particularly, the pneumatic actuating element16of

FIGS. 1 and 2has five air chambers17arranged next to one another in a row. However, more or fewer air chambers17may be provided. The air chambers17of the actuating element16can be filled with air to transfer the air guiding device into the operating position shown inFIG. 2, while air can be let out of the air chambers17to transfer the air guiding device into the inoperative position shown inFIG. 1. The air chambers form a pneumatic actuator for displacing the air guiding element13, and the actuating element16is mounted by a fastening strip18on the forward structure part11.

In the operating position (seeFIG. 2), the spoiler lip14forms a downwardly directed extension of the forward structure part11and is directed substantially rearwardly in the inoperative position (seeFIG. 1).

The elastically deformable sheet-like element15of the air guiding element13adjoins below the forward structure part11behind the spoiler lip14.

A front portion19of the elastically deformable sheet-like element15acts on a portion20of the spoiler lip14that is in a lower position when the spoiler lip14is in the operating position and that is in a rear position when the spoiler lip14is in the inoperative position. A rear portion21of the elastically deformable sheet-like element15of the air guiding element13is secured via a fastening strip22on a rear portion23of the forward structure part11.

The elastically deformable sheet-like element15has an outer contour that provides laminar flow guidance in the extended operating position of the air guiding element13shown inFIG. 2. At least one elastic tension band24acts on the sheet-like element15to bring and hold the elastic sheet-like element15into the shape of the extended operating position shown inFIG. 2for achieving laminar flow guidance.

The tension band24has a first end that acts on a central portion25of the sheet-like element15of the air guiding element13and a second end on the fastening strip18for the actuating elements16. Provision is made for the negative pressure to draw the sheet-like element15down, and, if appropriate, the actuator16also can press down. The tension band or bands24locally limit the downward deflection to ensure the ideal contour even at high speeds (high negative pressure).

Accordingly, in the embodiment ofFIGS. 1 and 2, the air guiding element13of the air guiding device12comprises the spoiler lip14and the elastically deformable sheet-like element15. The spoiler lip14extends the forward structure part11down in the extended operating position.

The pneumatic actuating element16with the multiple air chambers17is used to displace the spoiler lip14between the retracted inoperative position ofFIG. 1and the extended operating position ofFIG. 2. The actuating element16is secured on the fastening strip18acts on the lower portion20of the spoiler lip14in the operating position, and on the rear portion20of the spoiler lip14in the inoperative position.

The front end19of the elastic sheet-like element15of the air guiding element13also acts on the portion20of the spoiler lip14that is at a lower position in the extended operating position of the spoiler lip14and that is at a rear position in the inoperative position of the spoiler lip14. As a result, when extending the spoiler lip14into the operating position ofFIG. 2, the elastic sheet-like element15is stretched. The elastic tension band24acts on a central portion25of the sheet-like element15and cooperates with the actuating element16on the same portion of the fastening strip18to bring the sheet-like element15into a shape of defined curvature and to hold this shape so that the outer contour of the sheet-like element15functions for laminar flow guidance.

As shown inFIGS. 1 and 2, the forward structure panel11and the portion20of the spoiler lip14each are assigned a magnetic element26or27to hold the spoiler lip14in a defined position on the forward structure part11in the retracted inoperative position shown inFIG. 1.

FIGS. 3 and 4show a detail of an alternative front portion30of a motor vehicle in the region of a forward structure part31. The region of the forward structure part31of the motor vehicle again has an air guiding element33of an air guiding device32that extends completely or partially over the width of the forward structure part31. However, the air guiding element33ofFIGS. 3 and 4does not comprise a spoiler lip. Rather, the air guiding element33ofFIGS. 3 and 4is formed completely by an elastically deformable sheet-element35. The elastically deformable sheet-like element35is below the forward structure part31and acts with a front portion39on a front portion of the forward structure part31and with a rear portion41, via a fastening strip42, on a rear portion43of the forward structure part31.

The air guiding element33of the air guiding device32ofFIGS. 3 and 4is formed completely by the elastically deformable sheet-like element35, and can be displaced with the aid of an actuating element36between the retracted inoperative position ofFIG. 3and the extended operating position ofFIG. 4. The actuating element36once again is configured as a pneumatic actuating element with air cushions37that can be filled with air or emptied dependent on the desired displacement direction. A fastening strip38fastens the actuating element36to the forward structure part31.

InFIGS. 3 and 4, the actuating element36has three air cushions37that are positioned next to one another in a row. The actuating element36acts on a portion34of the elastically deformable sheet-like element35and on the fastening strip38. The portion34of the sheet-like element35on which the actuating element36acts is positioned between the portions39,42of the sheet-like element35.

At least one elastic tension band44acts on a portion40of the elastic sheet-like element35, as shown inFIG. 4. The tension band44brings the elastically deformable sheet-like element35into the shape shown inFIG. 4when in the extended operating position and holds that shape so that an outer contour achieves laminar flow guidance. The portion40of the elastic sheet-like element35on which the tension band44acts is between the portion34on which the actuating element36acts and the rear portion42of the sheet-like element35.

The tension band44acts with a first end on the portion40of the elastic sheet-like element35and with an opposite second end on the fastening strip38of the actuating element36. Thus, tension band44and actuating element36act on opposite portions of the fastening strip38.

The elastic sheet-like element35ofFIG. 4is held in the extended operating position via a further elastic tension band45to achieve the defined shape for laminar flow guidance. The further elastic tension band45acts with a first end together with the actuating element36on the portion34of the sheet-like element35. The further tension band45acts with an opposite second end on the fastening strip38of the actuating element36, namely together with the actuating element36on the same portion of the fastening strip38.

In the extended operating position ofFIG. 4, the elastic sheet-like element35is contoured or curved convexly out or down at a front portion and concavely in or up in the rear portion. In the extended operating position, the air guiding element33also provides a protection from damage in the event of a bottoming-out of the motor vehicle.

Magnetic elements46,47are provided to hold the air guiding element33in a defined position on the forward structure part31in the retracted inoperative position ofFIG. 3.

Common to both exemplary embodiments is that the air guiding element13or33has an elastically deformable sheet-like element15or35that is brought into a defined shape by at least one elastic tension band24or44,45in the extended operating position of the air guiding element13or33so that the outer contour of the elastic sheet-like element15or35serves for laminar flow guidance. An aerodynamically active component, such as a diffusor, positioned downstream of the air guiding device12or32thus can be subjected to improved flow.