Motor Vehicle Having a Rear Apron

Abstract

An exhaust system has at least one exhaust tailpipe which is led through a rear apron of the motor vehicle. The drive train of the vehicle has a rear axle. An air duct is provided in a rear region, which air duct supplies exterior air to the at least one exhaust tailpipe at least in sections. The rear axle has at least one rear axle cover at least in sections. An air inlet opening of the air duct is arranged behind the rear axle cover in a travel direction of the motor vehicle. As a result of the design of the motor vehicle, the rear apron is protected from impingement by hot exhaust gases.

Claims

1.-9. (canceled)

10. A motor vehicle having a drive train and an exhaust gas system with at least one exhaust gas end pipe, comprising: a rear apron through which the at least one gas end pipe is guided; an air guiding channel in a rear region of the motor vehicle, the air guiding channel supplying exterior air to the at least one exhaust gas end pipe at least partially; a rear axle cover of a rear axle of the drive train, wherein an air inlet opening of the air guiding channel is arranged in a travel direction of the motor vehicle behind the rear axle cover.

11. The motor vehicle according to claim 10, wherein a geodetically lower portion of the air guiding channel is arranged with respect to a standing surface of the motor vehicle at a height of the rear axle cover or lower.

12. The motor vehicle according to claim 10, wherein the air inlet opening of the air guiding channel is spaced apart from the rear axle cover by between 1 mm and 500 mm.

13. The motor vehicle according to claim 10, wherein the air inlet opening of the air guiding channel has a flow cross section between 100 mm.sup.2 and 1,000,000 mm.sup.2.

14. The motor vehicle according to claim 10, further comprising: a thermal insulation arranged in a region of the at least one exhaust gas end pipe between the exhaust gas end pipe and an inner rear region of the motor vehicle.

15. The motor vehicle according to claim 10, wherein the rear axle cover extends over at least one chassis component.

16. The motor vehicle according to claim 10, wherein the rear axle cover has, at an outer side thereof, a form of a flow guiding element.

17. The motor vehicle according to claim 16, wherein the rear axle cover is formed spherically or cylindrically in a downward direction.

18. The motor vehicle according to claim 10, wherein the air guiding channel has a flow cross section which is round, oval, angular or which changes in cross section.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG. 1 is a schematic X-Y section through a rear region of a motor vehicle according to the prior art;

[0024] FIG. 2 is a schematic X-Z section through a rear region of a motor vehicle according to an embodiment of the invention; and

[0025] FIG. 3 is a schematic X-Y section through the rear region of the motor vehicle according to an embodiment of the invention.

[0026] Below, for FIGS. 1 to 3, the same reference numerals apply to the same structural elements and the same gaseous materials.

DETAILED DESCRIPTION OF THE DRAWINGS

[0027] FIG. 1 shows a schematic X-Y section (transversely relative to a longitudinal and vertical vehicle axis) through a rear region 3 of 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 pipe 1 according to the prior art. The exhaust gas end pipe 1 is guided through an opening which has no reference numeral in the rear apron 2 of the motor vehicle. A hot exhaust gas which is discharged from the exhaust gas end pipe 1 is designated 12.

[0028] As can be seen in FIG. 1, the hot exhaust gas 12 forms in the rear region 3 of the motor vehicle an eddy which guides the hot exhaust gas 12 along the rear apron 2. Some rear apron forms, as in the present embodiment, bring about, in combination with the geometric embodiment of the exhaust gas end pipe 1, a return flow of the hot exhaust gas in and along the rear apron 2. The hot exhaust gas 12 consequently 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 apron 2.

[0029] FIG. 2 shows a schematic X-Z section (section through a longitudinal and vertical vehicle axis) through a rear region 3 of a motor vehicle according to the invention. An exhaust gas end pipe 1, from which hot exhaust gas 12 flows out, is illustrated again. The exhaust gas end pipe 1 is guided through an opening which has no reference numeral in the rear apron 2 of the motor vehicle.

[0030] 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 opening 7 of an air guiding channel 4 is arranged in a travel direction of the motor vehicle behind the rear axle cover 6. Above the rear axle cover 6, a chassis component 11, in this instance, for example, a shock absorber, is illustrated.

[0031] The air guiding channel 4 has a geodetically upper portion and a geodetically lower portion 8. The geodetically lower portion 8 of the air guiding channel 4 is arranged with respect to a standing surface of the motor vehicle at the height of the rear axle cover 6 or 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 cover 6 is achieved, whereby the cool air flows or slides or is accelerated into the air guiding channel 4. A flowing air 5 is illustrated schematically by means of arrows, wherein only a single arrow is given a reference numeral. This air 5 is conveyed further in the air guiding channel 4 and flows around the exhaust gas end pipe 1 at least partially and is subsequently at least partially discharged out of the rear apron 2 of the motor vehicle, wherein the air 5 is substantially discharged into the environment partially coaxially with respect to the exhaust gas end pipe 1.

[0032] Preferably, the air inlet opening 7 of the air guiding channel 4 is spaced between 1 mm and 500 mm apart from the rear axle cover 6. In this value range or spacing range, the effect according to the invention, the flowing through of the air guiding channel 4, is particularly well developed.

[0033] Furthermore, the air inlet opening 7 of the air guiding channel 4 has a flow cross section between 100 mm.sup.2 and 1,000,000 mm.sup.2. This is also a particularly preferred value range in which the effect according to the invention is particularly well developed. The air guiding channel 4 does 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.

[0034] In a development of the invention, in the region of the at least one exhaust gas end pipe 1 between the exhaust gas end pipe 1 and an inner rear region 9 a thermal insulation 10 is arranged. This prevents, on the one hand, overheating of the inner rear region 9 of the motor vehicle and further acts as a flow guiding element for selectively guiding the air in the air guiding channel 4. The thermal insulation 10 may, for example, be constituted by a metal or plastics material sheet or a temperature-resistant foam.

[0035] Preferably, the rear axle cover 6 extends over at least one chassis component 11, such as, for example, a shock absorber. This leads to the air inlet opening 7 of the air guiding channel 4 being arranged rather eccentrically in the direction of a side wall of the vehicle.

[0036] In a particularly preferred manner, the rear axle cover 6 is 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 opening 7 is thereby accelerated so that a particularly large amount of cool air flows through the air guiding channel 4.

[0037] In a particularly preferred manner, the rear axle cover 6 is constructed in a spherical or cylindrical manner in a downward direction. These embodiments ideally form a flow guiding element.

[0038] Furthermore, the air guiding channel 4 has 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 channel 4 can 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 channel 4 is in this instance formed mainly by body elements and other structural elements.

[0039] FIG. 3 shows similarly to FIG. 1 an X-Y section through the rear region 3 of the motor vehicle according to the invention. The exhaust gas end pipe 1 and the rear apron 2 through which the exhaust gas end pipe extends are illustrated again. An inner rear region is designated 9 again. A discharged hot exhaust gas is designated 12 again. According to the invention, the fresh, cool air 5 is discharged substantially partially coaxially with respect to the exhaust gas end pipe 1 out of the rear apron 2. As can be seen in FIG. 3, in place of the hot exhaust gas 12, the fresh, cool air forms, for example, an eddy or a partial fresh air jacket in the rear region 3 and thus keeps the hot exhaust gas 12 away from the surface of the rear apron 2 which according to the invention can no longer overheat.

[0040] The air inlet opening 7 of the air guiding channel 4 according to the invention thus taps cool, energy-rich underbody flow on the underbody of the motor vehicle downstream of the rear axle cover 6 and guides it to the at least one exhaust gas end pipe 1. The cooling air 5 supplied flows in the region between the rear apron 2 and the exhaust gas end pipe 1 at least partially out of the vehicle rear 3. On the one hand, a return flow of the exhaust gas 12 into the rear apron 2 is thereby prevented and, on the other hand, the return flow is displaced along the rear apron 2 (externally) and consequently away from the rear apron 2. As a result of these two effects, the rear apron temperature can be significantly reduced so that a melting of the rear apron 2 is prevented according to the invention.

LIST OF REFERENCE NUMERALS

[0041] 1. Exhaust gas end pipe [0042] 2. Rear apron [0043] 3. Rear region [0044] 4. Air guiding channel [0045] 5. Air [0046] 6. Rear axle cover (RAC) [0047] 7. Air inlet opening [0048] 8. Lower portion [0049] 9. Inner rear region [0050] 10. Thermal insulation [0051] 11. Chassis component [0052] 12. Exhaust gas