Patent ID: 12196118

Below, forFIGS.1to3, the same reference numerals apply to the same structural elements and the same gaseous materials.

DETAILED DESCRIPTION OF THE DRAWINGS

FIG.1shows a schematic X-Y section (transversely relative to a longitudinal and vertical vehicle axis) through a rear region3of a motor vehicle having a drive train (which is not illustrated) and having an exhaust gas system (which is not illustrated in greater detail) with an exhaust gas end pipe1according to the prior art. The exhaust gas end pipe1is guided through an opening which has no reference numeral in the rear apron2of the motor vehicle. A hot exhaust gas which is discharged from the exhaust gas end pipe1is designated12.

As can be seen inFIG.1, the hot exhaust gas12forms in the rear region3of the motor vehicle an eddy which guides the hot exhaust gas12along the rear apron2. Some rear apron forms, as in the present embodiment, bring about, in combination with the geometric embodiment of the exhaust gas end pipe1, a return flow of the hot exhaust gas in and along the rear apron2. The hot exhaust gas12consequently in an unfavorable manner brings about a local increase of the rear apron temperature, which (without the counter-measure according to the invention) in an extreme case can lead to melting of the surface of the rear apron2.

FIG.2shows a schematic X-Z section (section through a longitudinal and vertical vehicle axis) through a rear region3of a motor vehicle according to the invention. An exhaust gas end pipe1, from which hot exhaust gas12flows out, is illustrated again. The exhaust gas end pipe1is guided through an opening which has no reference numeral in the rear apron2of the motor vehicle.

According to the invention, a rear axle (which is not illustrated) has at least partially a rear axle cover (RAC)6, wherein an air inlet opening7of an air guiding channel4is arranged in a travel direction of the motor vehicle behind the rear axle cover6. Above the rear axle cover6, a chassis component11, in this instance, for example, a shock absorber, is illustrated.

The air guiding channel4has a geodetically upper portion and a geodetically lower portion8. The geodetically lower portion8of the air guiding channel4is arranged with respect to a standing surface of the motor vehicle at the height of the rear axle cover6or lower. As a result of this arrangement, an acceleration of the flowing air counter to a travel direction of the motor vehicle behind the rear axle cover6is achieved, whereby the cool air flows or slides or is accelerated into the air guiding channel4. A flowing air5is illustrated schematically by means of arrows, wherein only a single arrow is given a reference numeral. This air5is conveyed further in the air guiding channel4and flows around the exhaust gas end pipe1at least partially and is subsequently at least partially discharged out of the rear apron2of the motor vehicle, wherein the air5is substantially discharged into the environment partially coaxially with respect to the exhaust gas end pipe1.

Preferably, the air inlet opening7of the air guiding channel4is spaced between 1 mm and 500 mm apart from the rear axle cover6. In this value range or spacing range, the effect according to the invention, the flowing through of the air guiding channel4, is particularly well developed.

Furthermore, the air inlet opening7of the air guiding channel4has a flow cross section between 100 mm2and 1,000,000 mm2. This is also a particularly preferred value range in which the effect according to the invention is particularly well developed. The air guiding channel4does not in this instance have to be constituted by a separate component, but can instead be formed by means of body structural elements and/or other structural elements.

In a development of the invention, in the region of the at least one exhaust gas end pipe1between the exhaust gas end pipe1and an inner rear region9a thermal insulation10is arranged. This prevents, on the one hand, overheating of the inner rear region9of the motor vehicle and further acts as a flow guiding element for selectively guiding the air in the air guiding channel4. The thermal insulation10may, for example, be constituted by a metal or plastics material sheet or a temperature-resistant foam.

Preferably, the rear axle cover6extends over at least one chassis component11, such as, for example, a shock absorber. This leads to the air inlet opening7of the air guiding channel4being arranged rather eccentrically in the direction of a side wall of the vehicle.

In a particularly preferred manner, the rear axle cover6is formed at the outer side, that is to say, in the direction of the ground surface, as a flow guiding element. The air in the region of the air inlet opening7is thereby accelerated so that a particularly large amount of cool air flows through the air guiding channel4.

In a particularly preferred manner, the rear axle cover6is constructed in a spherical or cylindrical manner in a downward direction. These embodiments ideally form a flow guiding element.

Furthermore, the air guiding channel4has a flow cross section which is round and/or oval and/or angular and/or can change in cross section. That is to say, the air guiding channel4can take on almost any cross section and any cross sectional form and consequently can be adapted in an ideal manner to the body form of the motor vehicle. The air guiding channel4is in this instance formed mainly by body elements and other structural elements.

FIG.3shows similarly toFIG.1an X-Y section through the rear region3of the motor vehicle according to the invention. The exhaust gas end pipe1and the rear apron2through which the exhaust gas end pipe extends are illustrated again. An inner rear region is designated9again. A discharged hot exhaust gas is designated12again. According to the invention, the fresh, cool air5is discharged substantially partially coaxially with respect to the exhaust gas end pipe1out of the rear apron2. As can be seen inFIG.3, in place of the hot exhaust gas12, the fresh, cool air forms, for example, an eddy or a partial fresh air jacket in the rear region3and thus keeps the hot exhaust gas12away from the surface of the rear apron2which according to the invention can no longer overheat.

The air inlet opening7of the air guiding channel4according to the invention thus taps cool, energy-rich underbody flow on the underbody of the motor vehicle downstream of the rear axle cover6and guides it to the at least one exhaust gas end pipe1. The cooling air5supplied flows in the region between the rear apron2and the exhaust gas end pipe1at least partially out of the vehicle rear3. On the one hand, a return flow of the exhaust gas12into the rear apron2is thereby prevented and, on the other hand, the return flow is displaced along the rear apron2(externally) and consequently away from the rear apron2. As a result of these two effects, the rear apron temperature can be significantly reduced so that a melting of the rear apron2is prevented according to the invention.

LIST OF REFERENCE NUMERALS

1. Exhaust gas end pipe2. Rear apron3. Rear region4. Air guiding channel5. Air6. Rear axle cover (RAC)7. Air inlet opening8. Lower portion9. Inner rear region10. Thermal insulation11. Chassis component12. Exhaust gas