motor vehicle

Abstract

Motor vehicle comprising a body with an underbody (12), an underbody panel (11), an internal combustion engine (13), and an exhaust aftertreatment system for treating the exhaust gas, which can be supplied to the exhaust aftertreatment system via at least one exhaust manifold (15). Adjoining the underbody panel (11) is at least one first air guide element (18), which is arranged adjacent to and laterally connected to a respective rear wheel (10), and which is designed to divert a portion of the air flowing along the underbody (11) and direct it upwards and longitudinally to the rear.A second air guide element (19) adjoins each first air guide element (18), which is configured to deflect the air flowing over the respective first air guide element in a transverse direction and to direct it towards the exhaust manifold (15) or one of the exhaust manifolds (15) and at least one catalyst (14), and wherein the air flowing around the at least one exhaust manifold (15) and the at least one catalyst (14) is directed downstream of the at least one exhaust manifold (15) and downstream of the at least one catalyst (14) through a cavity formed between the underbody (12) and the underbody paneling (11), in which a silencer (16) is arranged, so that the air flows around the silencer (16) and, after flowing around it, exits the cavity into the environment via at least one flow outlet opening.

Description

[0001] The invention relates to a motor vehicle.

[0002] A motor vehicle has a body. The main component of the body is the underbody, which forms the lower boundary of the vehicle. Underbody panels are attached to the underbody.

[0003] Motor vehicles still have an internal combustion engine and an exhaust aftertreatment system that treats the exhaust gas leaving the engine. The exhaust aftertreatment system may include a particulate filter and a catalytic converter. The exhaust gas leaving the engine is fed to the exhaust aftertreatment system via an exhaust manifold.

[0004] Due to increasingly stringent requirements for exhaust aftertreatment, exhaust aftertreatment systems are becoming increasingly complex; in particular, the back pressure that the exhaust aftertreatment system opposes to the exhaust flow is increasing. As a result, the temperatures of components within the exhaust aftertreatment system, such as the catalytic converter, are also rising.

[0005] However, in order to operate the catalytic converter of the exhaust aftertreatment system at a stoichiometric air-fuel ratio of lambda equal to 1 (λ=1), the exhaust gas temperature at the catalytic converter must not become too high. Otherwise, it may be necessary to enrich the air-fuel ratio, i.e., to select an air-fuel ratio of lambda less than 1 (λ<1), in order to provide cooling in the area of ​​the catalytic converter by means of fuel. This must be avoided, however, to comply with emissions regulations.

[0006] There is a need for a motor vehicle in which exhaust gas temperatures in the area of ​​the exhaust aftertreatment system can be reduced in order to avoid enriching the air-fuel ratio to a lambda value of less than 1.

[0007] DE 10 2011 005 924 A1 discloses a motor vehicle according to the preamble of claim 1.

[0008] DE 10 2014 223 332 A1, DE 10 2020 103 196 A1, DE 10 2014 217 802 A1 and DE 102 16 969 B4 disclose further state of the art.

[0009] The object of the invention is to create a corresponding motor vehicle. This object is achieved by a motor vehicle according to claim 1.

[0010] According to the invention, at least one first air guide element adjoins the underbody paneling. This first air guide element is arranged adjacent to each rear wheel and is laterally connected to the respective rear wheel. It is configured to divert a portion of the air flowing along the underbody and direct it upwards in the vertical direction of the vehicle and backwards in the longitudinal direction of the vehicle. Adjoining each first air guide element is a second air guide element, which is configured to redirect the air flowing over the first air guide element in the transverse direction of the vehicle and to direct it towards the exhaust manifold or one of the exhaust manifolds and at least one catalyst of the exhaust aftertreatment system.

[0011] Furthermore, according to the invention, the air flowing around the at least one exhaust manifold and the at least one catalyst is directed downstream of the at least one exhaust manifold and downstream of the at least one catalyst through a cavity formed between the underbody and the underbody paneling, in which a silencer of the exhaust aftertreatment device is arranged, so that the air also flows around the end silencer, wherein, after flowing around the silencer, the air then exits from this cavity into the environment via at least one flow outlet opening.

[0012] In the motor vehicle according to the invention, a portion of the air flowing along the underbody is diverted and directed towards the at least one exhaust manifold and the at least one catalyst of the exhaust aftertreatment system, so that the exhaust gas temperature can ultimately be reduced.

[0013] The respective air guide element serves to divert the respective portion of the air flowing along the underbody. Downstream of the respective exhaust manifold and downstream of the at least one catalyst, the air flows through a cavity between the underbody and the underbody paneling, in which the silencer of the exhaust aftertreatment system, preferably designed as a rear silencer, is located. Subsequently, the air exits into the environment through at least one flow outlet opening. The invention makes it possible to effectively reduce the exhaust gas temperature, so that, particularly in the area of ​​a catalyst, the temperature can be lowered by approximately 20°C to 40°C. This eliminates the need to cool the catalyst with unburned fuel, thus allowing the air-fuel ratio to be maintained at a lambda value of 1 over a wider range of operating conditions.

[0014] Adjacent to the underbody paneling is at least one first air guide element, which is designed to divert a portion of the air flowing along the underbody and direct it upwards in the direction of the vehicle. Adjacent to each first air guide element is a second air guide element, which is designed to redirect the air flowing over the first air guide element laterally across the vehicle and towards the exhaust manifold or one of the exhaust manifolds and the at least one catalytic converter. The respective first air guide element then serves to divert the respective portion of the air flowing along the underbody, from which the diverted portion of the air is redirected via the respective second air guide element and directed towards the respective exhaust manifold(s) and the at least one catalytic converter.This allows the exhaust gas temperature to be reduced particularly effectively, thus eliminating the need to cool the catalyst via unburned fuel, and consequently the air-fuel ratio can be maintained at a lambda value of 1 across larger operating ranges.

[0015] The first air guide element is arranged adjacent to a rear wheel of the motor vehicle, with each first air guide element adjoining the respective rear wheel laterally. This is particularly preferred for diverting the air from the air flowing past the underbody paneling.

[0016] Preferably, the respective first air guide element transitions into the underbody paneling via a NACA opening. This is also particularly preferred for diverting the airflow. The use of NACA openings only slightly increases the vehicle's aerodynamic drag. Alternatively, instead of a NACA opening, the respective first air guide element can also transition into the underbody paneling via a diffuser.

[0017] The first air guide element is configured to direct a portion of the air flowing along the underbody upwards in the vertical direction of the vehicle and backwards in the longitudinal direction of the vehicle towards the respective subsequent second air guide element. This flow guidance for the portion of air diverted from the air flowing along the underbody is particularly preferred.

[0018] Preferably, the second air guide element also serves as a heat shield. This dual function of the second air guide element prevents components installed near the exhaust manifold and / or the exhaust aftertreatment system from being exposed to excessive heat. A separate heat shield is then unnecessary.

[0019] Preferably, the respective flow outlet opening in the rear area of ​​the vehicle, particularly in the rear area of ​​the underbody paneling, is located adjacent to the exhaust tailpipes of the exhaust aftertreatment system. This is particularly advantageous for guiding the flow of the portion of air that is diverted from the air flowing along the underbody, in order to discharge it back into the environment.

[0020] Preferably, the underbody paneling in the rear area of ​​the vehicle forms a diffuser. The invention is particularly advantageous when the underbody paneling in the rear area of ​​the vehicle is designed as a diffuser.

[0021] Preferred embodiments of the invention are described in the dependent claims and the following description. Exemplary embodiments of the invention are explained in more detail with reference to the drawing, without being limited thereto. The drawing shows: Fig. 1 a perspective view from below of a motor vehicle according to the invention, Fig. 2 a section of the motor vehicle according to the invention.

[0022] Fig. Figure 1 shows a perspective view of a motor vehicle from a low angle in the area of ​​a rear wheel 10. Also shown is an underbody panel 11 of the motor vehicle, which extends at least partially along the underbody 12 of the body of the motor vehicle.

[0023] The body of the motor vehicle, namely the underbody 12, is made in particular of a metallic material. The underbody paneling 11 is preferably made of a plastic.

[0024] The motor vehicle also has an internal combustion engine 13, which in the illustrated embodiment is installed in the rear area of ​​the motor vehicle, i.e., it is designed as a rear engine.

[0025] Such a motor vehicle with an internal combustion engine 13 also has an exhaust aftertreatment system, which serves in particular to clean the exhaust gas leaving the internal combustion engine 13. Components of such an exhaust aftertreatment system typically include a catalytic converter and / or a particulate filter. Fig. Figure 1 shows a catalyst 14.

[0026] The exhaust gas leaving the combustion engine 13 can be fed to the exhaust aftertreatment system, in the illustrated embodiment the catalyst 14, via at least one exhaust manifold 15. The exhaust gas guided from the combustion engine 13 towards the exhaust aftertreatment system via the at least one exhaust manifold 15 flows downstream of the catalyst 14 and a preferably present particulate filter (not shown) through a silencer, wherein Fig. Figure 2 shows a silencer 16 designed as a muffler. From the muffler 16, the exhaust gas flows into the environment via exhaust tailpipes 17.

[0027] In the motor vehicle according to the invention, a portion of the air flowing along the underbody 11 can be diverted and redirected via at least one air guide element 18, 19.

[0028] In the preferred embodiment shown, a portion of the air flowing along the underbody 11 is diverted from the air flowing along the underbody 11 via at least one first air guide element 18 and directed upwards in the upward direction of the motor vehicle, in accordance with Fig. 1 on the one hand upwards in the vertical direction of the motor vehicle and on the other hand to the rear in the longitudinal direction of the motor vehicle.

[0029] In the illustrated, preferred embodiment, a second air guide element 19 is connected to each first air guide element 18 in the direction of flow of the diverted air L. This second air guide element 19 is configured to redirect the air L flowing upwards and backwards over the first air guide element in the transverse direction of the vehicle and to direct it towards the respective exhaust manifold(s) 15, so that this air L flows around the exhaust manifold 15. The air L flowing around the exhaust manifold 15 cools the exhaust manifold(s) 15 and thus the exhaust gas flowing through the exhaust manifold 15.

[0030] In this way, a lower exhaust gas temperature can be ensured in the area of ​​the catalyst 14 and preferably the particulate filter, so that it is possible to do without enriching the air-fuel ratio to a lambda value less than 1.

[0031] In the illustrated embodiment, the air L deflected by the respective second air guide element 19 can also be directed towards the at least one catalyst 14 in order to flow around the catalyst 14. Furthermore, in the illustrated embodiment, the air L directed by the respective second air guide element 19 towards the exhaust manifold 15 and flowing around the exhaust manifold 15 can also flow around the catalyst 14 in the direction of flow.

[0032] According to Fig. 1 The respective first air guide element 18 and the respective second air guide element 19 are arranged adjacent to a respective rear wheel 10 of the motor vehicle in a transverse direction inside the motor vehicle 10.

[0033] The respective first air guide element 18 transitions into the underbody panel 11 via a flow opening, which is preferably designed as a NACA opening. This is particularly preferred with regard to the aerodynamic drag of the vehicle.

[0034] The air L, directed towards the at least one exhaust manifold 15 and flowing around the outside of the exhaust manifold 15 and / or the at least one catalyst 14, flows, in the direction of air flow, downstream of the respective exhaust manifold 15 and downstream of the at least one catalyst 14, through a cavity formed between the underbody 12 and the underbody panel 11, in which the rear silencer 16 is arranged, so that the air L also flows around the rear silencer 16. From this cavity, the air L exits into the environment via a flow outlet opening 20, which in the illustrated embodiment is provided in the rear area of ​​the vehicle.

[0035] In the illustrated embodiment, the respective flow outlet opening 20 is located in the rear area of ​​the motor vehicle, preferably in the rear area of ​​the underbody paneling 11, adjacent to the exhaust tailpipes 17.

[0036] The underbody panel 11 preferably forms a diffuser, with diffuser blades 21 preferably running below the flow outlet opening 20.

[0037] Preferably, at least one air guide element, in the illustrated embodiment the respective second air guide element 19, also serves as a heat shield. This prevents components installed in the area of ​​the respective exhaust manifold 15 from being exposed to excessively high temperatures from the exhaust gas. This is preferred to avoid the need for a separate heat shield.

[0038] The invention makes it possible to reduce the exhaust gas temperature in the area of ​​the respective exhaust manifold 15 and thus also downstream of the respective exhaust manifold 15 in the area of ​​a catalyst 14. This ultimately eliminates the need to enrich the air-fuel mixture to a lambda value of less than 1. Furthermore, this results in less aging of the exhaust aftertreatment system, enabling it to provide optimal exhaust aftertreatment over a longer period.

[0039] Although the embodiment with the at least one first air guide element 18 and the at least one second air guide element 19 is preferred, a single air guide element can also be used to direct the respective diverted air L to the at least one exhaust manifold 15 and / or the at least one catalyst 14.

[0040] The invention was granted with reference to Fig. 1 and Fig.2 describes the invention for a motor vehicle with a rear engine. However, the invention can also be used in a motor vehicle with a mid-engine as well as in a motor vehicle with a front engine. In such motor vehicles, the respective air guide element and / or the respective opening through which the respective air guide element transitions into the underbody paneling and / or the respective flow outlet opening through which the air exits into the environment, can be positioned at a different location, particularly in the longitudinal direction of the motor vehicle.

Claims

[1] motor vehicle, with a body having an underbody (12), with an underbody panel (11) attacking the underbody (12), with an internal combustion engine (13), with an exhaust aftertreatment device for the aftertreatment of the exhaust gas leaving the combustion engine (13), which can be supplied to the exhaust aftertreatment device via at least one exhaust manifold (15), characterized by , that at least one first air guide element (18) adjoins the underbody paneling (11), which is arranged adjacent to a respective rear wheel (10), which connects laterally to the respective rear wheel (10), and which is designed to divert a portion of the air flowing along the underbody (11) and direct it upwards in the vertical direction of the motor vehicle and to the rear in the longitudinal direction of the motor vehicle, a respective second air guide element (19) adjoins the respective first air guide element (18), which is designed to redirect the air flowing over the respective first air guide element (18) in a transverse direction of the motor vehicle and to direct it towards the exhaust manifold (15) or one of the exhaust manifolds (15) and at least one catalyst (14) of the exhaust aftertreatment device, the air flowing around the at least one exhaust manifold (15) and the at least one catalyst (14) is directed downstream of the at least one exhaust manifold (15) and downstream of the at least one catalyst (14) through a cavity formed between the underbody (12) and the underbody paneling (11), in which a silencer (16) of the exhaust aftertreatment device is arranged, so that the air also flows around the silencer (16), and wherein the air, after flowing around the silencer (16), exits this cavity into the environment via at least one flow outlet opening (20). [2] Motor vehicle according to claim 1, characterized by , that the respective first air guide element (18) transitions into the underbody paneling (11) via a NACA opening. [3] Motor vehicle according to claim 1 or 2, characterized by , that the respective second air guide element (19) also serves as a heat shielding plate. [4] Motor vehicle according to any one of claims 1 to 3, characterized by , that the respective flow outlet opening (20) in the rear area of ​​the motor vehicle is designed adjacent to exhaust tailpipes (17) of the exhaust aftertreatment device. [5] Motor vehicle according to claim 4, characterized by , that the respective flow outlet opening (20) is formed in the rear area of ​​the underbody paneling (11). [6] Motor vehicle according to any one of claims 1 to 5, characterized by , that the underbody paneling (11) forms a diffuser in the rear area of ​​the motor vehicle.

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