Motor vehicle having a front apron having duct-like air-guiding devices

A motor vehicle includes a body having a front apron, and an underbody. The body forms at least one left and one right front wheel house for receiving one front wheel each. The air-guiding devices have at least one left flow duct and at least one right flow duct. The at least one left flow duct opens in the underbody in front of the left wheel house. The at least one right flow duct opens in the underbody in front of the right wheel house. The respective exit opening is arranged in front of that region of the respective wheel house which is adjacent to the inner side, which faces the vehicle central plane, of the respective vehicle wheel in the straight-ahead position.

BACKGROUND AND SUMMARY OF THE INVENTION

Embodiments of the present invention relate to a motor vehicle, and in particular to a motor vehicle having a body having a front apron and an underbody, in which the body forms at least one left and one right front wheel house for receiving one front wheel each, and in which duct-like air-guiding devices are provided in the front apron, said air-guiding devices having an air inlet in the region of the front of the vehicle and an air outlet in the region of the underbody.

Various cooling air openings are provided in the front apron of modern motor vehicles. A lower cooling air inlet, openings for removed radiators and for brake cooling ducts are frequently located in the lower part of the front apron. In the region of the respective side of the vehicle to provide openings through which air is guided into the front outer edge of the respective wheel house in order to form a vertical air curtain laterally outside the front wheel. Such an air curtain deflects the relative wind past the front wheel and thereby reduces the air vortices in the region of the front wheel.

DE 32 45 410 A1 provides an air inlet opening of a flow duct in the front apron of a vehicle transversally over the width of the vehicle, the flow duct deflecting the entering air flow downward to the underbody in the region of the front apron and allowing the air to escape in a specific manner in the direction of travel. As a result, the intention, by means of the flat air jet, is for a type of spoiler to be formed in the region of the front apron, the spoiler deflecting the relative wind around the vehicle.

DE 10 2007 045 004 A1 presents and describes an air-guiding device in the form of a wheel spoiler which is arranged in front of the front wheel of a vehicle and is situated in the flow that shields the front wheel against the incident relative wind. The wheel spoiler is provided with one or more guiding fins which are intended to channel the flow in the region of the wheel and the wheel house in order thereby to minimize air vortices occurring at a wheel spoiler.

FR 2 858 796 A1 presents and describes an air-guiding device in the front of a vehicle, which air-guiding device comprises an air-guiding duct which extends from the front of the vehicle to shortly before the wheel house of the front wheel and, in a region directly in front of the wheel, opens downward in the direction of the carriageway. The mouth here is configured in such a manner that the exiting air in front of the wheel in the straight-ahead position exits at an angle to the perpendicular toward the carriageway and toward the outer side of the vehicle. As a result, the front wheel is intended to be protected against direct impinging of the relative wind against the wheel, and the vortices of the relative wind caused by the rotating vehicle wheel are intended to be reduced. A component of the vehicle, namely the front wheel, is therefore shielded here by the deflection of a partial flow of the relative wind impinging against the vehicle.

DE 10 2009 040 678 A1 discloses a wheel spoiler which extends on the underbody of the vehicle in front of a front wheel and a front wheel house in the transverse direction of the vehicle and which has an inner portion with a spoiler-lip separation edge not running rectilinearly, said portion extending in front of the inner free part of the wheel house, and therefore said portion is arranged substantially away from overlapping with an inner tire flank, as seen in the direction of flow. This spoiler lip with an uneven separation edge is intended to shield the region of the wheel house between the inner tire flank in the straight-ahead position of the wheel and the inner side of the wheel house against incident air. The ram lip which is formed by the wheel spoiler and has a non-rectilinear contour is intended to bring about a change in the flow, in particular by having an influence on the shearing layer, wherein the intention is to obtain a reduction in the inflow into the wheel house by means of local changes in the flow speed and the flow orientation at the non-rectilinear contour.

SUMMARY OF THE INVENTION

One of the objects of the embodiments of the present invention is to design a motor vehicle of the type in question in such a manner that the aerodynamics of the motor vehicle in the region of the wheel house are further improved in order to reduce the air resistance of the vehicle.

This and other objects are achieved by a motor vehicle of the type in question, in which the air-guiding devices have at least one left flow duct and at least one right flow duct, in which the at least one left flow duct opens in the underbody in front of the left wheel house and the at least one right flow duct opens in the underbody in front of the right wheel house, and in which the respective exit opening forming the air outlet is designed in such a manner that the air flowing through the flow duct exits counter to the direction of travel with a direction component downward. The respective exit opening is arranged in front of that region of the respective wheel house which is adjacent to the inner side, which faces the vehicle central plane, of the respective vehicle wheel in the straight-ahead position.

In accordance with the inventive motor vehicle, the particular position of the respective exit opening cause the channeled air emerging from the exit opening of the flow duct to deflect the relative wind air flowing freely along under the underbody of the vehicle in front of that part of the wheel house which is adjacent to the inner side of the wheel downward, i.e. toward the carriageway. This gives rise under that free part of the wheel house which is not taken up by the vehicle wheel in the straight-ahead position to a horizontal air curtain which reduces vortices of the relative wind flowing along under the vehicle in the wheel house, in particular at the wheel suspension and steering components, and thus reduces the flow resistance of the motor vehicle. An additional reduction in the flow resistance is provided by the air entry openings of the flow duct, said air entry openings forming the air inlet, since air entry openings reduce the vehicle end surface.

In stark contrast to existing motor vehicles that use wheel spoilers, in the inventive motor vehicle a partial flow is introduced into the underbody flow (virtual discharge), wherein the discharged partial flow brings about a deflection of the underbody flow and therefore a shielding or a “virtual sealing” of the open part of the wheel house. In addition, by means of a corresponding configuration of the duct, the partial flow flowing through the duct can be accelerated, which results in turn in an acceleration of the underbody flow at the duct outlet. Therefore, in stark contrast to existing motor vehicles, in the inventive motor vehicle no component located in the flow is shielded; instead, the flow passes over an opening present in the vehicle underbody and said opening is virtually closed off or “virtually sealed”.

Advantageously, the position of the respective exit opening and the extent thereof in the transverse direction of the vehicle may be dimensioned in such a manner that the exit opening takes up or overlaps the distance from the inner side, which faces toward the vehicle center plane, of the respective vehicle wheel in the straight-ahead position as far as the inner side of the wheel house, the inner side facing the respective vehicle wheel, i.e. the entire width of that free part of the wheel house which is not taken up by the vehicle wheel in the straight-ahead position. The extent of the exit opening in the transverse direction of the vehicle is therefore not smaller here than the width of the free part of the wheel house. By this means, that free part of the wheel house which is adjacent to the inner side of the wheel is reliably shielded over its entire width with the horizontal air curtain, and vortices of the vehicle underflow are thus substantially suppressed in the free part of the wheel house.

Additionally, the respective exit opening may have an exit cross section provided, at least on one longitudinal side, with a contour differing from a straight line. This contour differing from the straight line can be of stepped, zigzag-shaped or wavy design or is provided with convex bulges lying laterally against one another.

Alternatively or in addition, the respective exit opening may be of rectangular design in outline and is preferably arranged at a right angle to the vehicle central plane. However, it is also possible for the respective exit opening to be of curved or sickle-shaped design in outline, wherein its curvature preferably substantially corresponds to the curvature of the front edge of the wheel house, as viewed in outline, or is approximate to said curvature. It is also possible for only the rear edge of the exit opening, which edge is adjacent to the wheel house, to be of curved or sickle-shaped design and for it to be matched to the curvature of the front edge of the wheel house.

Advantageously, at least one vortex-generating element may be provided upstream of the exit opening in the respective flow duct. Said vortex-generating element can be, for example, a triangular vortex generator or in region of the flow duct upstream of the exit opening that is designed as a countersunk inlet.

Further, a ram lip or a displacer which protrudes downward from the underbody may be provided on or in front of the front edge of the respective exit opening. Said optional ram lip in front of the exit opening of the duct facilitates the discharge of the partial flow conducted through the duct by a local negative pressure being produced at the duct outlet by the provision of the ram lip or of the displacer.

Advantageously, the upper wall of the flow duct can be of concave, convex or concave-convex design in the region of the respective exit opening.

Alternatively or in addition, the upper wall of the flow duct can also have a concavely, convexly or concavely-convexly curved profile over the course of the flow duct.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1is a greatly simplified illustration of the front left side of a motor vehicle in a perspective view. The motor vehicle comprises a body1having a front apron2and an underbody3(FIG. 3). The body1in a conventional manner forms a left wheel house10for receiving a left front wheel12. Although only the left front side of the motor vehicle is illustrated inFIG. 1, the explanations in this regard also apply, of course, to the right side of the vehicle which is constructed mirror-symmetrically with respect thereto.

Duct-like air-guiding devices4are provided in the front apron2, said air-guiding devices each having an air inlet40in the region of the front of the vehicle for some of the relative wind W impinging on the front apron2, and having an air outlet42(FIG. 3) in the region of the underbody. Although only the left air-guiding device4is shown inFIG. 1, a correspondingly configured air-guiding device is also provided mirror-symmetrically with respect thereto on the right side.

FIG. 2, which reproduces a simplified horizontal section through the front apron2of the vehicle shown inFIG. 1, shows the profile of the left flow duct44of the air-guiding device4. The flow duct44runs from the air inlet40in the front apron2through the front apron2toward the front region of the underbody3in which the air outlet42of the left flow duct44is formed by a corresponding exit opening43in the underbody3. Said air outlet42is located in the underbody just before the front edge10′ of the wheel house10, as seen in the direction of travel F.

As can readily be seen inFIG. 2, the exit opening43, which forms the air outlet42, of the left flow duct44lies, as viewed in the transverse direction of the vehicle, adjacent to the inner side12′, which faces toward the vehicle central plane M, of the left front vehicle wheel12in a straight-ahead position. The exit opening43extends in the transverse direction of the vehicle, i.e. perpendicularly to the vehicle central plane M, over the entire width of that free part of the wheel house10which is not taken up by the vehicle wheel12in the straight-ahead position, i.e. from the inner side12′ of the front vehicle wheel12in the straight-ahead position as far as the inner side, which faces toward the vehicle wheel12, of the wheel house10, or slightly beyond the latter, as can be seen inFIG. 2. The air flowing out of the exit opening43is therefore not conducted onto the front vehicle wheel12, but rather is conducted laterally next to the front vehicle wheel12, specifically next to the inner side12′ of the vehicle wheel12, as is explained in more detail further below.

FIG. 3shows a side view of the front part of the motor vehicle which is partially illustrated inFIG. 1, wherein the front apron2is cut open in the region of the flow duct44. It can readily be seen in this figure that the flow duct44of the duct-like air-guiding device4runs from the air inlet40obliquely downward to the air outlet42which is formed by the exit opening43in the underbody3, until just in front of the front edge10′ of the wheel house10.

InFIG. 3Awhich corresponds toFIG. 3, the profile of the flow caused by the relative wind W through the flow duct44and along under the underbody3of the vehicle can be seen. The relative wind flow W impinging on the front apron2is divided at corresponding front edges20,22of the front apron2above and below the air inlet40, and therefore some of the relative wind which is not deflected upward or to the side by the front apron2is conducted through the flow duct44. This duct flow, denoted by W1, of the relative wind exits downward again through the exit opening43, which forms the air outlet42, of the flow duct44on the underbody3along the direction of travel F with a direction component caused by the flow duct44running obliquely rearward and downward and impinges there against the underflow W2produced by the relative wind W under the underbody3of the vehicle. In the region shortly before the wheel house10, in which the duct flow W1impinges against the underflow W2in a manner directed obliquely rearward and downward, the underflow W2is deflected downward by the duct flow W1in the direction of the carriageway surface S. This is symbolized by the two right vertical arrow columns inFIG. 3A. This deflection of the underflow in the direction of the carriageway surface S prevents substantial parts of the underflow W2from being sucked into the wheel house by the negative pressure formed in the wheel house10in front of the front vehicle wheel12in the direction of travel and swirling in said wheel house. The duct flow W1exiting from the flow duct44therefore deflects the underflow W2downward in the direction of the carriageway surface S and therefore past the negative pressure field U formed in the wheel house in front of the front wheel. As a result, the vortices of the underflow W2in the wheel house10are significantly reduced and therefore the flow losses are reduced in this region, as a result of which the air resistance of the motor vehicle is likewise reduced.

FIGS. 4 to 7show alternative cross-section forms of the exit opening43to the rectangular embodiment of the exit opening43that is illustrated inFIG. 2.

InFIG. 4, the contour43A of the exit opening is provided at its front edge in the direction of travel F with a central, step-like enlargement45of the exit cross section.

InFIG. 5, the contour43B of the exit opening is provided on its front edge in the direction of travel F with convex bulges45′ which lie next to one another and locally constrict the exit cross section.

FIG. 6illustrates a variant of the exit opening43with a differing contour43C in which the front edge, in the direction of travel F, of the exit opening43is designed as a zigzag-shaped edge45″.

FIG. 7shows a further alternative of the exit opening43with a curved contour43D which is of curved design in outline, wherein the curvature of the contour43D, in particular in the region of the rear edge43D′ of the exit opening43, substantially corresponds to the curvature of the front edge10′ of the wheel house10, i.e. runs parallel to the curved front edge10′ of the wheel house10. By this means, an optimal design of the horizontal air curtain below the wheel house10is achieved.

FIGS. 8 to 11correspond to the partially sectioned view ofFIG. 3and show different duct geometries.

The duct geometry of the flow duct44ofFIG. 8substantially corresponds to that inFIG. 3, wherein the exit opening43is, however, slightly larger than in the example ofFIG. 3. The flow duct44K1is somewhat constricted in cross section in its central portion and thereby forms a venturi tube in which the duct flow is accelerated. The flow duct44K1runs substantially with a rectilinear duct axis from the air inlet40obliquely rearward and downward to the exit opening43.

The flow duct44K2illustrated inFIG. 9runs substantially parallel without the constriction typical of a venturi tube and, in its rear region just in front of the exit opening43, has a significantly downwardly directed curvature.

The duct geometry, which is shown inFIG. 10, of the flow duct44K3runs from the air inlet40to the exit opening43in a narrower downwardly directed curve than in the example ofFIG. 9, wherein the exit opening43lies significantly in front of the front edge10′ of the wheel house10. The distance of the rear edge43′ of the exit opening43from the front edge10′ of the wheel house10corresponds here approximately to the width (as measured in the direction of travel) of the exit opening43.

FIG. 11illustrates a further duct geometry of the flow duct44K4, in which the flow duct44K4runs from the air inlet40inclined obliquely rearward and downward approximately at an angle of 45° to the exit opening43and is greatly constricted here. The duct geometry therefore corresponds approximately to the front part of a venturi tube as far as the neck, but without having the diffuser typical of a venturi tube. In this duct configuration, the exit opening43lies even further forward than in the example ofFIG. 10and is located approximately at half the distance between the air inlet40and the front edge10′ of the wheel house10. At the air outlet formed by the exit opening43, this duct geometry delivers a greatly accelerated, obliquely rearwardly and downwardly directed duct flow which, because of its accelerated flow speed, exerts a great displacement effect on the underflow.

FIGS. 12 to 14show, using the example of the duct geometry ofFIG. 8, the provision of different outlet geometries of the respective flow duct44in the region of the exit opening43.

The upper wall46of the flow duct44can have an upwardly directed concave bulge46A2in the region of the exit opening43, as is illustrated inFIG. 12, or a downwardly directed convex bulge46A3as is illustrated inFIG. 13. Alternatively, the upper wall46of the flow duct44can also have a combination of the configurations according toFIGS. 12 and 13in the region of the exit opening43and can therefore form a concave-convex profile46A4, as illustrated inFIG. 14, wherein the convex part is provided behind the concave part in the direction of travel F. The modifications of the outlet geometry of the duct44that are illustrated inFIGS. 12 to 14can be provided, of course, not only for the duct geometry44K1ofFIG. 8, but also for the duct geometries shown inFIGS. 9 to 11.

Irrespective of the configuration of the duct geometry and of the outlet geometry, the front edge43″ of the respective exit opening43can be provided with a ram lip5which protrudes downward, as is illustrated inFIG. 15. Instead of the ram lip5, a displacer6which protrudes downward from the underbody3, as illustrated inFIG. 16, can alternatively also be provided. The ram lip5or the displacer can also be provided in front of the front edge43″ in the direction of travel.

FIG. 17shows a further modified configuration of the flow duct44in a view corresponding toFIG. 2in which a depression44′ of the flow duct44is provided in front of the front edge43″ of the outlet opening43, said depression starting from the center of the duct and expanding to the sides of the flow duct44and leading to the outlet opening43and being designed in the manner of an NACA countersunk inlet.FIG. 17Ashows that this configuration of the flow duct44with the duct depression44′ leads to the production of the two vortices which are located laterally next to each other and rotate in opposite directions and exit through the exit opening43and impinge against the underflow W2. It can be seen inFIG. 17BandFIG. 17Cthat the profile of the flow duct44and the contour thereof in the center of the duct corresponds to the duct contour of the flow ducts described up to now, for example to the embodiment ofFIG. 8, while the flow duct has a lower height toward the side edges and extends abruptly downward. The resulting different flow conditions in the center of the duct and at the edge of the duct ensure the swirling of the duct flow that is shown inFIG. 17A.

FIG. 18shows another modified configuration of the flow duct44in a view corresponding toFIG. 2in which a depression44″ of the flow duct44is provided in front of the obliquely running front edge43″′ of the outlet opening43, said depression44″ being positioned on one side of the flow duct44and extending to the other side of the flow duct44and leading to the outlet opening43and being designed similarly to a NACA countersunk inlet.FIG. 18Ashows that this configuration of the flow duct44with the duct depression44″ which is asymmetric with respect to the center of the duct leads to the production of a vortex which exits through the exit opening43and impinges against the underflow W2.

FIG. 19shows yet another modified configuration of the flow duct44in a view corresponding toFIG. 2, wherein a vortex-generating element7is provided in the flow duct44in front of the front edge43″ of the outlet opening43, as seen in the direction of travel F. As illustrated inFIG. 19, said vortex-generating element7can be an interfering body which is rectangular in cross section or can be of curved cross-sectional design. In the example ofFIG. 19, the vortex-generating element7is at an oblique angle, for example of approximately 45°, to the front edge43″ of the exit opening43of rectangular configuration.FIG. 19Ashows the vortex generated by the vortex-generating element7.

FIG. 19Bshows, in a vertical section, the arrangement of the vortex-generating element7on the lower duct wall just in front of the exit opening43.FIG. 19Bfurthermore shows an upper vortex-generating element7′ as an alternative or in addition to the lower vortex-generating element7provided on the lower duct wall, said upper vortex-generating element7′ being provided on the upper duct wall in the region of the exit opening43and extending into the flow duct.

The embodiments of the invention are not restricted to the above exemplary embodiment which serves merely to generally explain the core concept of the invention. On the contrary, within the scope of protection the device according to the invention may also take on different embodiments than those described above. The device here may have features in particular which constitute a combination of the respective individual features of the claims.

Reference signs in the claims, the description and the drawings serve merely for better understanding of the embodiment of the invention and are not intended to restrict the scope of protection.