Aerodynamically constructed covering part for the underside of a motor vehicle

At least one vent hole is provided on an aerodynamically constructed covering part for the underside of a motor vehicle. A partial flow of the cold fresh air flows through the vent hole between the covering part and the roadway and is guided to a space which is situated above and accommodates assemblies and/or chassis parts. At least one suction device is provided on the covering part for carrying away the heated air situated in the space disposed above in the direction of the roadway.

BACKGROUND AND SUMMARY OF THE INVENTION

This application claims the priority of German Application No.: 103 41 642.0 filed Sep. 10, 2003, the disclosure of which is expressly incorporated by reference herein.

The invention relates to an aerodynamically constructed covering part for the underside of a motor vehicle, particularly a passenger car. The covering part has a vent hole through which a partial flow of the cold fresh air flowing through between the covering part and the roadway during the driving operation is guided to a space which is situated above and accommodates assemblies and/or chassis parts, such as the engine compartment and/or transmission space or the like. The partial flow cools the assemblies and/or chassis parts situated there.

Increasingly, the aerodynamic optimization of vehicles takes place at the underside of the vehicle. Here, it is endeavored to implement an underbody having a smooth-surface covering. However, these coverings have the disadvantage that covered areas heat up more intensely. The reason is the insufficient exchange between, on one hand, heated air in the engine compartment and transmission space and, on the other hand, fresh cooling air. The known vent holes permit the targeted feeding of cold fresh air.

A problem arises, however, when already heated outgoing air mixes with the fresh air provided for the cooling, or when incoming and outgoing air conduction devices have a faulty design or do not exist. Furthermore, the aerodynamic advantages of a smooth underbody are considerably impaired by conventional venting concepts.

From German Patent Document DE-AS 1 286 917, a passenger car is known which is equipped with an aerodynamically constructed covering part on its underside. A grille in the form of several slots is provided below the engine on the covering part for venting the engine compartment.

In this arrangement, during the driving operation, a partial flow of the cold fresh air guided through between the covering part and the roadway is conducted through the slots to the engine situated above.

However, German Patent Document DE-AS 1 286 917 does not contain any information as to how the air heated by the engine is discharged from the engine compartment.

It is an object of the invention to further develop an aerodynamically constructed covering part for the underside of a motor vehicle according to the initially mentioned type such that, when the aerodynamic potential of a smooth underbody is utilized, simultaneously the air flowing through the engine compartment and the transmission space is fed and carried away in a targeted and therefore efficient manner.

According to certain preferred embodiments of the invention, this object is achieved by providing an aerodynamically constructed covering part for the underside of a motor vehicle, particularly a passenger car. At least one vent hole is provided on the covering part, through which a partial flow of cold fresh air flowing through between the covering part and the roadway during the driving operation is guided to a space which is situated above and accommodates assemblies and/or chassis parts, such as the engine compartment and/or transmission space or the like. The partial flow cools the assemblies and/or chassis parts situated there, and at least one suction device is provided on the covering part for carrying away the heated air situated in the space disposed above in the direction of the roadway. The at least one suction device being arranged at a distance from the vent hole.

Other advantageous features of Preferred embodiments of the invention are described herein and the claims.

Important advantages achieved by means of the invention are that, as a result of the arrangement of at least one suction device on the covering part, the air circulating through the engine compartment and transmission space is divided in a defined manner into a cooling incoming-air conduction and an outgoing-air conduction carrying away the heated air. As a result of the spatially offset arrangement of the at least one suction device with respect to the vent hole, it is achieved that only cold fresh air is fed to the engine compartment and transmission space, whereas the heated air flows out laterally beside the vent hole and then flows along the underside of the vehicle and is carried away toward the rear.

The suction effect is created in certain preferred embodiments of the invention by aerodynamically optimized suction gills, which form a vacuum zone at the covering part. Viewed in the longitudinal direction of the vehicle, the transversely extending suction gills are arranged in a spaced manner behind one another and are set against the air flow guided through between the roadway and the covering part. The suction gills extend from the covering part downward in the direction of the roadway and have a blade-shaped cross-section. The shape and the position of the suction gills are adapted to the respective cooling task and have the advantage that the aerodynamic coefficients are impaired only insignificantly.

An embodiment of the invention is illustrated in the drawing and will be explained in detail in the following.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG. 1illustrates a motor vehicle1formed by a passenger car, whose underside3extending adjacent to a roadway2is provided with an aerodynamically constructed covering part4. The covering part4, which is preferably made of a plastic material or of a light metal, has a smooth surface in the direction of the roadway2and is held in position in a known manner on the vehicle body situated above it. It preferably covers the entire vehicle underside and may be constructed in one or more parts. The illustrated motor vehicle1is equipped with a mid-engine or a rear engine.

A space6which accommodates assemblies and/or chassis parts extends in the rear area5of the motor vehicle1above the covering part4. In the embodiment shown, an engine7and an adjoining transmission8are arranged in the space6.

So that, in the case of a complete underbody covering, certain assemblies and/or chassis parts situated above the covering part are sufficiently cooled in the driving operation, at least one vent hole9is arranged on the covering part4, through which vent hole9a partial flow B of the cold fresh air A guided through between the roadway2and the covering part4is branched off upward into the space6. In the embodiment shown, the vent hole9extends on both sides of a longitudinal center plane C-C of the vehicle and has a width D.

At the forward and rearward end of the vent hole9, which is approximately rectangular in the top view, upward-oriented curved guide sections10,11are constructed on the covering part4or on an attachment part, by means of which guide sections10,11the partial flow B of the cold fresh air A is guided upward to the underside of the transmission8. The partial air flow B flows along the transmission underside12, cools this surface in the process, and heats up as a result. The heated air flows upward at the transmission end13and flows toward the front on the top side14of the transmission and on the top side15of the engine. At the forward upper end16of the engine7, the air is deflected again and flows between the engine7and an adjoining, transversely extending upright partition wall17in the downward direction (FIGS. 2 and 3).

By means of the at least one suction device18according to the invention provided on the covering part4, the air on the forward lower end of the engine7is deflected in the direction of the suction device18. In this case, the air flows past the outlet manifolds of the exhaust system and heats up intensively. As a result of the suction effect of the suction device18, the hot air is now transported from the engine compartment6to the outside, flows along the underside of the vehicle and is carried away toward the rear.

If cooling fresh air is additionally fed to the engine compartment6through another vehicle-body-side vent hole19, the cooling air follows the illustrated flow direction and intensifies the cooling effect around the engine7. In the embodiment shown, the transmission8is arranged behind the engine7. However, the function is ensured also when the arrangement is reversed.

According to the invention, the at least one suction device18provided at the covering part4is formed by several suction gills20which, viewed in the longitudinal direction of the vehicle, are arranged behind one another. The suction gills20are set against the air flow A flowing through between the covering part4and the roadway2and extend from the covering part4slightly downward in the direction of the roadway2(FIG. 4). Transversely extending air passage openings21extend between the individual suction gills20. In the embodiment shown, two laterally arranged suction devices18are provided which extend on both sides of the central vent hole9and each have a width E. However, there is also the possibility of arranging the suction device18in a central area and to arrange the vent holes9in a laterally exterior area of the covering part4. In the embodiment shown, viewed in the driving direction F, the forward end of the suction device18is situated in front of the vent hole9, whereas the rearward end of the suction devices18approximately coincides with the rearward end of the vent hole. However, this situation may also be different.