Motor vehicle with tailgate

Abstract

Exhaust system with at least one exhaust end pipe (1) which penetrates a rear apron (2) of a motor vehicle, the powertrain having a rear axle and the motor vehicle having an air guiding channel (4) in the rear region (3) which at least partially loads the at least one exhaust end pipe (1) with air (5) from the outside, wherein the rear axle has at least partially a rear axle cover (6) and the air entry opening (7) of the air guiding channel (4) is arranged behind the rear axle cover (6) in the driving direction of the motor vehicle. Based on the configuration of the motor vehicle according to the invention, the rear apron is protected from being loaded with hot exhaust gases.

Description

Technical Field

[0001] This invention relates to a motor vehicle. Background Technology

[0002] The rear area of ​​a motor vehicle equipped with an internal combustion engine contains components of the exhaust system, such as the rear muffler and exhaust terminal pipes. These components become very hot during operation and therefore require sufficient cooling, typically achieved through airflow. The diffuser in the rear area acts as an underbody shield, protecting the rear muffler from the airflow flowing beneath the vehicle. Cooling airflow to the rear muffler or exhaust terminal pipes can be facilitated, for example, through large openings in the diffuser within the rear muffler area. However, such openings for cooling the rear muffler or exhaust terminal pipes lose their potential for lift targets and drag coefficients. The efficiency of such cooling measures is generally low, resulting in temperatures in the exhaust system area often approaching below acceptable limits, even considering all optimization measures.

[0003] During driving, the vehicle's airflow creates low-pressure levels, particularly around the exhaust manifold and in the rear axle area. This can cause hot exhaust gases exiting the exhaust manifold to flow back into this low-pressure area under unfavorable conditions, such as in the tailgate and underbody protection, especially when the exhaust system has a visible exhaust manifold. This backflow results in additional, undesirable heat input in the rear area, specifically in the vehicle's tailgate.

[0004] An air steering device for influencing the tail vortex in the rear region of a motor vehicle is known from German utility model DE 297 21 562 U1. This air steering device, implemented as a channel, directs a portion of the air into the wake region behind the vehicle's rear, while another portion of the air flows rearward through a rear portion formed as a diffuser. The advantage in terms of drag coefficient comes from the reduction in the rear base surface, as the rear opening of the channel removes a portion of the rear base surface.

[0005] An air steering device in the rear region of a motor vehicle is known from German publication DE 199 61 316 A1. This air steering device directs air flowing beneath the vehicle's underside into an air collection housing. This air collection housing extends into an end-pipe orifice plate through which an exhaust end pipe is guided. The airflow introduced into the end-pipe orifice plate through the air collection housing pushes the exhaust backward and prevents exhaust backflow.

[0006] European Patent EP 2 834 138 B1 describes a diffuser with an air inlet for a rear muffler. The diffuser should completely cover the rear muffler and have an air inlet for cooling air behind it. A large opening is provided in the diffuser surface to accommodate the large structural height of the rear muffler. However, the diffuser loses its potential in terms of drag coefficient and lift targets due to this large opening. Cooling air should be driven primarily by pressure difference into the space surrounding the rear muffler covered by the diffuser. After absorbing waste heat from the rear muffler, the heated cooling air should flow forward below the diffuser shroud.

[0007] In DE 10 2015 108 509 A1, an air deflector is provided in the rear area of ​​a motor vehicle, which is intended to cool the rear muffler via an air inlet in the vehicle's underside. The air introduced there circulates around the rear muffler for cooling purposes and is directed upwards or directly to the surrounding environment at the rear of the vehicle, where a negative pressure exists.

[0008] US 6,435,298 B1 shows and describes a bottom structure for a motor vehicle that is spaced apart from the underside of a rear muffler disposed in the longitudinal direction, such that airflow can pass through the resulting intermediate space along the rearward path below the rear muffler. This airflow exits at the rear of the vehicle. This facilitates cooling of the underside of the rear muffler.

[0009] A motor vehicle having a bottom guard located in the rear region is known from an unpublished German patent application (DE 10 2020 103 196.3, from which this invention originates). The bottom guard is positioned below a rear-mounted muffler of the exhaust system. The rear-mounted muffler is equipped with at least one exhaust outlet and at least one exhaust end pipe extending from the rear muffler to the rear of the vehicle. The bottom guard is equipped with at least one air inlet through which air flowing under the vehicle is guided to a region above the bottom guard. The at least one exhaust outlet is equipped with at least one exhaust end pipe perforation plate, which at least partially surrounds the at least one exhaust end pipe and forms an airflow channel between the exhaust end pipe and the exhaust end pipe perforation plate. This airflow channel is open towards the region above the bottom guard and towards the rear of the vehicle. In this configuration, the airflow channel forms an air outlet exiting from the region above the bottom guard. Summary of the Invention

[0010] The objective of this invention is to design this type of motor vehicle to ensure adequate cooling of the vehicle's tailgate in the area of ​​the exhaust pipe.

[0011] The task is solved by the feature of the present invention, namely, the rear axle has at least partially a rear axle cover and an air inlet opening for an air guide channel is provided behind the rear axle cover in the direction of travel of the vehicle.

[0012] The air guide channel according to the invention intercepts the cold, high-energy (kinetic) underflow of the vehicle (downstream of the Rear Axle Cover (RAC)) through its air inlet opening and directs this underflow toward the at least one exhaust end pipe. The delivered cooling air flows into the rear of the vehicle in the area between the tailgate and the at least one exhaust end pipe. Thus, exhaust backflow into the tailgate is prevented on the one hand, and on the other hand, the backflow is directed away from the tailgate along its surface (externally). Through these two effects, the tailgate temperature is significantly reduced, thereby reliably preventing tailgate overheating. In this case, the air guide channel does not necessarily have to be a separate component, but can be formed by body elements and other structural elements.

[0013] Based on a specific embodiment of a motor vehicle configuration, wherein the section of the air guide channel that is geodetically located below the vehicle's vertical surface is positioned at or below the height of the rear axle cover, a cold, high-energy underflow is guided into the air guide channel.

[0014] According to one specific embodiment, the distance between the air inlet opening of the air guide channel and the rear axle cover is between 1 mm and 500 mm, which is a particularly preferred range, within which the cooling function of the rear bumper according to the invention is very good.

[0015] According to one specific embodiment, the air inlet opening of the air guide channel has a diameter of 100 mm. 2 With 1000000mm 2 The flow cross-section between these points is also a particularly preferred range, in which the cooling of the rear baffle according to the invention works very well.

[0016] According to one specific embodiment, a heat insulation portion is provided in the region of the at least one exhaust end pipe between the exhaust end pipe and the interior rear region to advantageously prevent overheating of the rear region of the vehicle interior. Additionally, the heat insulation portion also serves as a flow guiding element to selectively direct air toward the rear of the vehicle. The heat insulation portion may be, for example, made of a metal plate, a plastic plate, or a heat-resistant foam material.

[0017] According to one particular embodiment, the rear axle cover extends over at least one chassis component, which is a particularly preferred variation. The chassis component is understood, for example, as a shock absorber. This results in the air intake openings of the air guide channels being positioned more precisely off-center, i.e., towards the sidewall of the vehicle.

[0018] Particularly preferably, the rear axle cover is configured as a flow guiding element on the outer side, i.e. downward, according to one specific embodiment, thereby further enhancing the effect according to the invention, i.e., the flowing air is accelerated into the area of ​​the air inlet opening of the air guiding channel and the air guiding channel is improved for the flow of cooling air.

[0019] The rear axle cover is preferably spherical, cylindrical, or downwardly shaped according to one specific embodiment, which is a preferred embodiment of the flow guiding element.

[0020] The air guide channel, according to one specific embodiment, has a circular or elliptical or angular or variable flow cross-section, indicating that the air guide channel can accept almost any geometry. As already mentioned, the air guide channel is not necessarily a single component, but can be formed from body elements and / or additional components. Attached Figure Description

[0021] The invention will now be briefly explained with reference to the three accompanying drawings.

[0022] Figure 1 An XY-section is schematically shown through the rear region of a motor vehicle according to the prior art.

[0023] Figure 2 An XZ-section is schematically shown passing through the rear region of a motor vehicle according to the invention.

[0024] Figure 3 An XY-section is schematically shown passing through the rear region of a motor vehicle according to the invention. Detailed Implementation

[0025] Next, for Figures 1 to 3 In general, the same reference numerals apply to the same structural elements and the same gaseous substances.

[0026] Figure 1 The diagram schematically shows an XY-section (transverse to the vehicle's longitudinal and vertical axes) passing through the rear region 3 of a motor vehicle according to the prior art, which has a powertrain (not shown) and an exhaust system with an exhaust end pipe 1 (not shown in more detail). The exhaust end pipe 1 is guided through an unnumbered opening in the rear bumper 2 of the motor vehicle. The hot exhaust gas discharged from the exhaust end pipe 1 is numbered 12.

[0027] As in Figure 1 As can be seen, the hot exhaust 12 forms a vortex in the rear region 3 of the vehicle, which guides the hot exhaust 12 along the rear bumper 2. As in the current embodiment, some rear bumper shapes, in combination with the geometry of the exhaust end pipe 1, result in hot exhaust in the rear bumper 2 and flowing back along it. The hot exhaust 12 thus adversely causes localized increases in the temperature of the rear bumper, which (in the absence of a corresponding measure according to the invention) can, in extreme cases, lead to melting of the surface of the rear bumper 2.

[0028] Figure 2 An XZ-section (a section passing through the longitudinal and vertical axes of the vehicle) is schematically shown through the rear region 3 of the motor vehicle according to the invention. An exhaust end pipe 1 is also shown, from which hot exhaust gas 12 flows. This exhaust end pipe 1 is guided through an unnumbered opening in the rear bumper 2 of the motor vehicle.

[0029] According to the present invention, the rear axle (not shown) at least partially has a rear axle cover 6 (rear axle cover, RAC), wherein an air inlet opening 7 for an air guide passage 4 is provided behind the rear axle cover 6 in the direction of vehicle travel. A chassis component 11 is shown above the rear axle cover 6, which in the present embodiment is, for example, a shock absorber.

[0030] The air guide channel 4 has a geodetically upper section and a geodetically lower section 8. The geodetically lower section 8 of the air guide channel 4 is positioned at or below the height of the rear axle cover 6 with respect to the upright surface of the vehicle. This arrangement allows the flowing air to be accelerated behind the rear axle cover 6 in the opposite direction to the vehicle's direction of travel; thus, cool air is either guided or accelerated into the air guide channel 4. The flowing air 5 is schematically shown by arrows, with only one arrow numbered. The air 5 continues to be delivered in the air guide channel 4 and flows at least partially around the exhaust end pipe 1 and is then at least partially discharged from the rear tailgate 2 of the vehicle, wherein the air 5 is discharged largely coaxially with the exhaust end pipe 11 into the surrounding environment.

[0031] Preferably, the distance between the air inlet opening 7 of the air guide channel 4 and the rear axle cover 6 is between 1 mm and 500 mm. The effects according to the invention (through-flow air guide channel 4) are particularly well demonstrated within this size or distance range.

[0032] In addition, the air inlet opening 7 of the air guide channel 4 has a diameter of 100mm. 2 With 1000000mm 2The flow cross-section between [the components]. This is also a particularly preferred size range, in which the effects according to the invention are particularly well exhibited. In this case, the air guide channel 4 does not necessarily have to be presented by a separate component, but can be formed by vehicle body structural elements and / or other structural elements.

[0033] In an extended embodiment of the invention, a heat insulation portion 10 is provided between the exhaust end pipe 1 and the internal tail region 9 in the region of the at least one exhaust end pipe 1. This prevents the rear region 9 inside the vehicle from overheating and also serves as a flow guiding element to selectively guide air in the air guiding channel 4. The heat insulation portion 10 may be made of, for example, a metal plate, a plastic plate, or a heat-resistant foam material.

[0034] Preferably, the rear axle cover 6 extends over at least one chassis component 11 (e.g., a shock absorber). This causes the air inlet opening 7 of the air guide channel 4 to be positioned more precisely off-center in the direction of the vehicle sidewall.

[0035] Particularly preferably, the rear axle cover 6 is configured as a flow guiding element on its outer side, i.e., in the direction toward the earth's surface. This design accelerates the air in the area of ​​the air inlet opening 7, causing a particularly large amount of cool air to flow through the air guiding channel 4.

[0036] Particularly preferably, the rear axle cover 6 is shaped downwards in a spherical or cylindrical form. This embodiment ideally forms the flow guiding element.

[0037] Furthermore, the air guide channel 4 has a circular and / or elliptical and / or angular and / or variable flow cross-section. This indicates that the air guide channel 4 can accept almost any cross-section and any cross-sectional shape, and therefore can ideally adapt to the body shape of a motor vehicle. In this case, the air guide channel 4 is mainly formed by body elements and other structural elements.

[0038] like Figure 1 , Figure 3 An XY-section is shown passing through the rear region 3 of the vehicle according to the invention. Also shown is the exhaust end pipe 1 and the rear baffle 2 through which the exhaust end pipe 1 passes. The interior rear region is further designated 9. The exhausted hot exhaust is further designated 12. According to the invention, fresh, cold air 5 is largely locally and coaxially with the exhaust end pipe 1 discharged from the rear baffle 2. (As in...) Figure 3 As can be seen, fresh, cold air 5 now replaces the hot exhaust 12, for example, forming vortices or localized fresh air jackets in the tail region 3, and thus prevents the hot exhaust 12 from contacting the surface of the rear baffle 2, which, according to the invention, will no longer overheat.

[0039] According to the invention, the air inlet opening 7 of the air guide channel 4 intercepts a cold, high-energy bottom flow at the bottom of the vehicle, downstream of the rear axle cover 6 (downstream of the rear axle cap (RAC),) and directs this bottom flow toward the at least one exhaust end pipe 1. The delivered cooling air 5 flows out at least partially from the rear of the vehicle 3 in the area between the rear bumper 2 and the exhaust end pipe 1. This prevents the exhaust 12 from flowing back into the rear bumper 2 on the one hand, and on the other hand, causes the backflow to move along the rear bumper 2 (outside) and thus away from the rear bumper 2. Through these two effects, the temperature of the rear bumper can be significantly reduced, thus preventing the rear bumper 2 from melting according to the invention.

[0040] List of reference numerals

[0041] 1. Exhaust end pipe

[0042] 2. Rear bumper

[0043] 3. Tail area

[0044] 4. Air guiding channel

[0045] 5. Air

[0046] 6. Rear axle cover

[0047] 7. Air enters the opening

[0048] 8. The section below

[0049] 9. The internal tail area

[0050] 10. Insulation section

[0051] 11 Chassis Components

[0052] 12 Exhaust

Claims

1. A motor vehicle having a powertrain and an exhaust system, the exhaust system having at least one exhaust end pipe (1) guided through a rear tailgate (2) of the motor vehicle, the powertrain having a rear axle and the motor vehicle having an air guide passage (4) in a rear region (3) that at least partially loads air (5) onto the at least one exhaust end pipe (1) from the outside, characterized in that, The rear axle has at least a partial rear axle cover (6) and the air inlet (7) of the air guide channel (4) is located behind the rear axle cover (6) in the direction of travel of the vehicle. The air inlet (7) of the air guide channel (4) intercepts the cold, high-energy bottom airflow downstream of the rear axle cover (6) at the bottom of the vehicle and guides the bottom airflow toward the at least one exhaust end pipe (1). The cold air (5) is discharged from the rear baffle (2) partially and coaxially with the exhaust end pipe (1), so that a vortex or a local fresh air jacket is formed in the rear region (3), and thus prevents the hot exhaust (12) from contacting the surface of the rear baffle (2).

2. The motor vehicle according to claim 1, characterized in that, The section (8) of the air guide channel (4) located below the rear axle cover (6) with respect to the vertical surface of the vehicle is positioned at or below the height of the rear axle cover (6).

3. The motor vehicle according to claim 1 or 2, characterized in that, The distance between the air inlet (7) of the air guide channel (4) and the rear axle cover (6) is between 1 mm and 500 mm.

4. The motor vehicle according to claim 1 or 2, characterized in that, The air inlet (7) of the air guide channel (4) has a 100mm opening. 2 With 1000000mm 2 The flow cross section between them.

5. The motor vehicle according to claim 1 or 2, characterized in that, A heat insulation portion (10) is provided between the exhaust end pipe (1) and the internal tail region (9) in the region of the at least one exhaust end pipe (1).

6. The motor vehicle according to claim 1 or 2, characterized in that, The rear axle cover (6) extends over at least one chassis component (11).

7. The motor vehicle according to claim 1 or 2, characterized in that, The rear axle cover (6) is configured as a flow guide element on the outer side.

8. The motor vehicle according to claim 1 or 2, characterized in that, The rear axle cover (6) is shaped downwards in a spherical or cylindrical manner.

9. The motor vehicle according to claim 1 or 2, characterized in that, The air guide channel (4) has a circular or elliptical or angular or variable flow cross-section.

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