DE102021102847A1 - Exhaust gas cooling device for a motor vehicle and motor vehicle - Google Patents

Abstract

The invention relates to an exhaust gas cooling device (10) for a motor vehicle, having a cooling device (12) which is set up for exhaust gas and a cooling fluid (16) to flow through, as a result of which heat can be dissipated from the exhaust gas to the cooling fluid (16), and which has at least one exhaust gas duct (14), which is set up for the exhaust gas to flow through, which has a cooling area (20) around which the cooling fluid (16) flows and is cooled, and an uncooled inflow area (22) through which the exhaust gas flows into the exhaust gas duct (14), and with a heat protection device (26) which is designed to direct the exhaust gas without contact to the inflow area (22) and through the inflow area (22) into the cooling area (20) of the respective exhaust gas duct (14) respectively.

Description

The invention relates to an exhaust gas cooling device for a motor vehicle and a motor vehicle with an exhaust gas cooling device.

From the EP 1 444 474 B1 discloses an exhaust gas heat exchanger with a tube bundle through which exhaust gas can flow and a housing through which coolant can flow, the tube ends of the tube bundle being cohesively connected to tube sheets and the tube sheets being cohesively connected to the housing, and the housing having an expansion element. In the case of this exhaust gas heat exchanger, thermal stresses due to different expansions are to be reduced or avoided in order to avoid destruction of a tube-plate connection. For this purpose, a sealing element designed as a metal bellows is arranged on the housing, which covers and seals the expansion element. Furthermore, it is provided that the housing or a region of the housing has slots running transversely to the longitudinal direction of the tubes and in the circumferential direction of the housing as an expansion element. These slots each extend over only part of the circumference and partially overlap with axially offset slots in the circumferential direction.

The object of the present invention is to create a solution by means of which material stresses in a heat exchanger of an exhaust gas cooling device can be kept particularly low.

This object is achieved according to the invention by the subject matter of the independent patent claim. Further possible configurations of the invention are disclosed in the dependent claims, the description and the figures.

The invention relates to an exhaust gas cooling device for a motor vehicle, having a cooling device which is designed for exhaust gas and a cooling fluid to flow through. As a result, heat can be dissipated from the exhaust gas to the cooling fluid. The cooling device also has at least one exhaust gas duct through which the exhaust gas flows. This exhaust gas duct has a cooling area around which the cooling fluid flows and is cooled, and an uncooled inflow area, via which the exhaust gas flows into the exhaust gas duct. The cooling device is therefore a heat exchanger, by means of which the exhaust gas flowing through the heat exchanger can be cooled. The exhaust gas cooling device also includes a heat protection device, which is set up to guide the exhaust gas without contact to the inflow area and through the inflow area into the cooling area of the respective exhaust gas duct. The heat protection device thus enables the exhaust gas to be routed into the interior of the heat exchanger. This avoids the exhaust gas flow impinging directly on uncooled areas of the cooling device. The non-contact introduction of the exhaust gas through the inflow area into the cooling area of the respective exhaust gas duct allows material stresses in the cooling device to be kept particularly low. By avoiding hot exhaust gas impinging directly on uncooled areas of the cooling device, temperature differences of the material occurring in the cooling device can be kept particularly low. As a result, material stresses in the cooling device can in turn be kept particularly low, as a result of which a particularly long service life of the cooling device can be achieved.

In a further embodiment of the invention, it is provided that the heat protection device has a guide tube for each exhaust gas duct, which protrudes into the respective assigned exhaust gas duct of the cooling device and by means of which the exhaust gas can be guided into the cooling area. By means of the respective guide pipes, the exhaust gas can thus be guided without contact to the respective walls of the cooling device delimiting the exhaust gas duct in the inflow area, through the inflow area and into the cooling area of the cooling device. By means of the guide pipes, the exhaust gas can thus be guided without contact to the respective walls delimiting the exhaust gas ducts in the inflow area of the cooling device, past these walls and into the cooling area. In the cooling area, the exhaust gas can come into contact with the respective walls of the cooling area that delimit the exhaust gas duct. The guide tubes of the heat protection device provided for each exhaust gas duct thus make it possible for the exhaust gas to be prevented from impinging on uncooled areas of the cooling device.

In this context, it is provided in particular that the heat protection device has a collection area which is set up to collect exhaust gas flowing into the exhaust gas cooling device and to distribute it to the at least one guide tube, in particular to distribute it to the several guide tubes assigned to the respective exhaust gas ducts. The collection area enables the exhaust gas to be distributed evenly over the respective guide pipes, which in turn means that the exhaust gas can be evenly distributed over the respective exhaust gas ducts of the cooling device. As a result, the exhaust gas can be cooled particularly uniformly and particularly efficiently by means of the cooling device. white Furthermore, a particularly uniform temperature distribution can be achieved in the cooling device, as a result of which material stresses in the cooling device can be kept particularly low.

In a further embodiment of the invention, it is provided that the heat protection device is arranged so that it is not in direct contact with the cooling device. This means that there is no direct contact between the heat protection device and the cooling device. Thus, the heat protection device is consistently spaced apart from the cooling device. Because there is no direct contact between the heat protection device and the cooling device, direct heat conduction from the heat protection device to the cooling device is prevented. As a result, local heating of the cooling device due to contact with the heat protection device can be avoided. Due to the contact-free arrangement of the heat protection device with respect to the cooling device, the cooling device can be thermally insulated relative to the heat protection device via air.

In a further embodiment of the invention, it is provided that the heat protection device is set up to conduct the exhaust gas past a front side of the cooling device. Thus, the heat protection device is configured to prevent the exhaust gas from entering directly onto the front side of the cooling device. The front side of the cooling device is arranged at the front in particular in the direction of flow and is therefore passed first by the exhaust gas flowing into the cooling device. In particular, the front side can be part of the uncooled inflow area, as a result of which major material stresses could occur in the cooling device if hot exhaust gases hit the front side of the cooling device directly. In order to avoid these material stresses in the cooling device, the heat protection device directs the exhaust gas past the front side of the cooling device. For this purpose, the heat protection device can cover the front side of the cooling device in the direction of flow of the exhaust gas at least in regions, in particular completely. The front side of the cooling device can have an opening for each exhaust gas duct, through which the respective exhaust gas duct opens into the environment. A guide tube of the heat protection device can be inserted into each of the openings, as a result of which the exhaust gas can be guided into the cooling area without direct contact with the inflow area by means of the heat protection device. By directing the exhaust gas past the front side of the cooling device by means of the heat protection device, temperature differences between the front side of the cooling device and the cooling area of the cooling device can be kept particularly low, which in turn means that material stresses in the cooling device can be kept particularly low.

In a further embodiment of the invention, an inlet funnel is provided, via which the exhaust gas can flow into the exhaust gas cooling device, to which the cooling device is connected in the direction of flow and which encloses the heat protection device. The exhaust gas can thus be guided to the heat protection device and the cooling device by means of the inlet funnel. In particular, the inlet funnel is provided to guide the exhaust gas flowing into the exhaust gas cooling device into the collection area of the heat protection device. Flowing past the heat protection device and/or the cooling device can thus be at least essentially prevented by means of the inlet funnel. It is thus possible to prevent the exhaust gas from flowing through the exhaust gas cooling device without the exhaust gas being cooled.

In this context, it is provided in particular that the cooling device and the heat protection device are each materially connected to the inlet funnel in areas spaced apart from one another. This means that both the heat protection device and the cooling device each have a material connection with the inlet funnel. As a result, the cooling device and the heat protection device can be positioned without contact relative to one another via the inlet funnel. The inlet funnel thus holds the heat protection device and the cooling device in a position relative to one another in which there is no direct contact between the heat protection device and the cooling device. Both the heat protection device and the cooling device are held particularly securely on the inlet funnel via the integral connection.

Provision can also be made here for the cooling device and/or the heat protection device to be soldered to the inlet funnel. The soldered connection is a materially bonded connection that is particularly easy to provide and particularly stable.

In a further embodiment of the invention, it is provided that the heat protection device is provided by a heat protection plate. In this case, the heat protection device can in particular be provided continuously from a single material, as a result of which the risk of corrosion of the heat protection device can be kept particularly low. For particularly high mechanical stability, the heat protection device can in particular be designed in one piece. Alternatively, the heat protection device can be designed in several parts. Due to the non-contact arrangement of the heat protection In relation to the cooling device, the heat protection device can heat up at least essentially uniformly due to the exhaust gas flowing through the heat protection device, with the heat protection device not being cooled by the cooling device. As a result, the heat protection device can only have particularly small temperature differences, which in turn means that material stresses in the heat protection device can be kept particularly low. As a result of the particularly low material stresses in the heat protection device, the heat protection device can have a particularly long service life.

The invention also relates to a motor vehicle with an exhaust gas cooling device, as has already been described in connection with the exhaust gas cooling device according to the invention. The exhaust gas cooling device can in particular be set up to receive and cool exhaust gas from an internal combustion engine of the motor vehicle. The cooled exhaust gas can be made available by the exhaust gas cooling device for recirculation into the internal combustion engine of the motor vehicle. Advantages and advantageous developments of the exhaust gas cooling device according to the invention are to be regarded as advantages and advantageous developments of the motor vehicle according to the invention and vice versa.

Further features of the invention can result from the claims, the figures and the description of the figures. The features and feature combinations mentioned above in the description and the features and feature combinations shown below in the description of the figures and/or in the figures alone can be used not only in the combination specified in each case, but also in other combinations or on their own, without going beyond the scope of the invention to leave.

• 1 eine schematische Schnittansicht einer Abgaskühleinrichtung für ein Kraftfahrzeug, mit einer an einem Einlasstrichter befestigten Kühleinrichtung, mittels welcher die Abgaskühleinrichtung durchströmendes Abgas gekühlt werden kann, sowie mit einer Hitzeschutzeinrichtung, welche an dem Einlasstrichter befestigt und kontaktfrei zu der Kühleinrichtung angeordnet ist und mittels welcher das Abgas kontaktfrei zu der Kühleinrichtung durch einen Einströmbereich der Kühleinrichtung hindurch in einen Kühlbereich der Kühleinrichtung führbar ist; und
• 2a und 2b eine schematische Perspektivansicht der Hitzeschutzeinrichtung sowie eine schematische Perspektivansicht der Kühleinrichtung, mit mehreren von dem Abgas durchströmbaren Abgasführungskanälen, wobei sich durch den Kühlbereich der Kühleinrichtung hindurch erstreckende Abgasführungskanäle mittels eines durch die Kühleinrichtung strömenden Kühlfluids kühlbar sind.

The drawing shows in:

• 1 a schematic sectional view of an exhaust gas cooling device for a motor vehicle, with a cooling device attached to an inlet funnel, by means of which the exhaust gas flowing through the exhaust gas cooling device can be cooled, and with a heat protection device, which is attached to the inlet funnel and arranged without contact with the cooling device and by means of which the exhaust gas is contact-free can be guided to the cooling device through an inflow area of the cooling device and into a cooling area of the cooling device; and
• 2a and 2 B a schematic perspective view of the heat protection device and a schematic perspective view of the cooling device, with a plurality of exhaust gas ducts through which the exhaust gas can flow, wherein exhaust gas ducts extending through the cooling region of the cooling device can be cooled by means of a cooling fluid flowing through the cooling device.

In the figures, identical and functionally identical elements are provided with the same reference symbols.

In 1 an exhaust gas cooling device 10 is shown in part, which can be used in a motor vehicle. The exhaust gas cooling device 10 is configured to receive and cool exhaust gas from an internal combustion engine of a motor vehicle. The cooled exhaust gas can be made available by means of the exhaust gas cooling device 10 for recirculation into the internal combustion engine.

The exhaust gas cooling device 10 comprises a cooling device 12 designed as a heat exchanger, which in 2 B is shown separately in perspective. The cooling device 12 can also be referred to as a so-called cooling cassette. The cooling device 12 has a plurality of exhaust gas ducts 14 through which exhaust gas can be guided through the cooling device 12 . Furthermore, the cooling device 12 has cooling channels 18 through which a cooling fluid 16 can flow, in which the cooling fluid 16 can flow within the cooling device 12 . The cooling fluid 16 can be used to absorb heat from the exhaust gas flowing through the exhaust gas ducts 14 , as a result of which the exhaust gas can be cooled. The cooling device 12 has a cooling area 20 cooled by the cooling fluid 16 and an uncooled inflow area 22 . In particular, a front side 24 of the cooling device 12 is located in the inflow area 22 and is therefore not directly cooled by the cooling fluid 16 .

In order to prevent hot exhaust gas from directly impinging on the front side 24 and/or other parts of the inflow area 22, whereby temperature differences of a material of the cooling device 12 occurring in the cooling device 12 can be kept particularly low, the exhaust gas cooling device 10 comprises in addition to the cooling device 12 a Heat protection device 26. The heat protection device 26 is in 2a shown separately in a schematic perspective view. In the present case, the heat protection device 26 is provided by a heat protection plate. Here, the heat protection device 26 is provided from a single material. In particular, the heat protection device 26 is formed in one piece. The heat protection device 26 is set up to guide the exhaust gas through the inflow area 22 and without contact to the inflow area 22 into the cooling area 20 of the cooling device 12 . Thus, by means of of the heat protection device 26, the exhaust gas flowing into the exhaust gas cooling device 10 is guided through the inflow area 22 of the cooling device 12, direct contact between the exhaust gas and surfaces of the cooling device 12 in the inflow area 22 being avoided. As a result, large temperature differences and, as a result, material stresses of the cooling device 12 between the inflow area 22 and the cooling area 20 can be at least essentially avoided.

In order to be able to guide the exhaust gas through sections of the exhaust gas ducts 14 of the cooling device 12 assigned to the inflow area 22, the heat protection device 26 has a guide tube 28 for each exhaust gas duct 14, which is inserted into the respective assigned exhaust gas duct 14. The respective guide tubes 28 are not in direct contact with the respective walls delimiting the exhaust gas ducts 14, as a result of which the guide tubes 28 are thermally insulated from the section of the exhaust gas duct 14 assigned to the inflow area 22 by air. The exhaust gas can be conducted via the guide pipes 28 past the front side 24 of the cooling device 12 into sections of the exhaust gas ducts 14 assigned to the cooling area 20 . In this way, a direct impingement of the exhaust gas on the front side 24 of the cooling device 12 can be avoided. The heat protection device 26 has, as in 1 can be recognized particularly well, furthermore a collecting area 30 in which exhaust gas received from the heat protection device 26 can be collected. The exhaust gas collected in the collection area 30 is then distributed to the guide tubes 28 . As a result, the exhaust gas flowing into the heat protection device 26 can be evenly distributed over all the guide tubes 28 of the heat protection device 26 . In order to avoid direct thermal conduction from the heat protection device 26 to the cooling device 12, in particular to the inflow area 22 of the cooling device 12, the heat protection device 26 is not in direct contact with the cooling device 12.

The exhaust gas cooling device 10 comprises an inlet funnel 32 for positioning and holding the heat protection device 26 relative to the cooling device 12. By means of the inlet funnel 32, the exhaust gas can be guided into the collecting area 30 of the heat protection device 26 and, on the other hand, the heat protection device 26 can be moved in its position relative to the Cooling device 12 fixed. In the present case, both the cooling device 12 and the heat protection device 26 are each materially connected to the inlet funnel 32, in this case soldered. All connection points of the heat protection device 26 on the inlet funnel 32 are at a distance from all connection points of the cooling device 12 with the inlet funnel 32 . As a result, heat conduction from the heat protection device 26 via the inlet funnel 32 to the cooling device 12 can be kept particularly low. The exhaust gas can flow into the exhaust gas cooling device 10 via the inlet funnel 32 . The cooling device 12 adjoins the inlet funnel 32 in the direction of flow 34 . Furthermore, it is provided here that the inlet funnel 32 encloses the heat protection device 26 starting from the direction of flow 34 on the outer circumference.

In the exhaust gas cooling device 10 , thermally most highly stressed points in an inlet area of the exhaust gas cooling device 10 are decoupled by preventing exhaust gas from impinging directly on the front side 24 of the cooling device 12 . A direct flow of the main cracks on the front side 24 of the cooling device 12 can thus be prevented. This decoupling is achieved by providing the heat protection device 26 , which is in contact with the inlet funnel 32 , which is particularly hot during operation, and is arranged without contact with the cooling device 12 . The configuration of flow-guiding outlet points, in this case the provision of the guide pipes 28 of the heat protection device 26, enables exhaust gas to enter the exhaust gas ducts 14 of the cooling device 12 in a defined manner 12 introduced, in which a coolant flow sufficient for a removal of this heat flow is available. The cooling device 12 can be soldered or connected in some other way to the inlet funnel 32 in areas of the cooling device 12 that the cooling fluid 16 does not flow directly around, in particular in the inflow area 22. In particular, connection points of the cooling device 12 to the inlet funnel 32 are at a particularly large distance to connection points of the heat protection device 26 with the inlet funnel 32 . As a result, high temperature gradients based on thermal conduction to the cooling device 12 from the heat protection device 26 can be avoided. The greatest possible tightness of the connection between the heat protection device 26 and the inlet funnel 32 makes it possible, at least essentially, to prevent parasitic heat flows which can reach the cooling device 12 .

Overall, the invention shows how a heat shield can be used in an exhaust gas recirculation cooler.

Reference List

10

exhaust gas cooling device

12

cooling device

14

exhaust duct

16

cooling fluid

18

cooling channel

20

cooling area

22

inflow area

24

front

26

heat protection device

28

guide tube

30

collection area

32

inlet funnel

34

flow direction

QUOTES INCLUDED IN DESCRIPTION

This list of documents cited by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Patent Literature Cited

• EP 1444474 B1 [0002]

Claims (10)

Exhaust gas cooling device (10) for a motor vehicle, with a cooling device (12) which is set up for exhaust gas and a cooling fluid (16) to flow through, as a result of which heat can be dissipated from the exhaust gas to the cooling fluid (16), and which has at least one Has exhaust gas duct (14), which is set up to be flowed through by the exhaust gas, which has a cooling area (20) around which the cooling fluid (16) flows and is cooled, and an uncooled inflow area (22), via which the exhaust gas enters the exhaust gas duct ( 14) flows in, and with a heat protection device (26) which is set up to guide the exhaust gas without contact to the inflow area (22) and through the inflow area (22) into the cooling area (20) of the respective exhaust gas duct (14). Exhaust gas cooling device (10) after claim 1 , characterized in that the heat protection device (26) has a guide tube (28) for each exhaust gas duct (14), which projects into the respective associated exhaust gas duct (14) of the cooling device (12) and by means of which the exhaust gas can be guided into the cooling area (20). is. Exhaust gas cooling device (10) after claim 2 , characterized in that the heat protection device (26) has a collecting area (30) which is set up to collect the exhaust gas flowing into the exhaust gas cooling device (10) and to distribute it to the at least one guide tube (28). Exhaust gas cooling device (10) according to one of the preceding claims, characterized in that the heat protection device (26) is arranged so that it is not in direct contact with the cooling device (12). Exhaust gas cooling device (10) according to one of the preceding claims, characterized in that the heat protection device (26) is set up to conduct the exhaust gas past a front side (24) of the cooling device (12). Exhaust gas cooling device (10) according to one of the preceding claims, characterized in that an inlet funnel (32) is provided, via which the exhaust gas can flow into the exhaust gas cooling device (10), to which the cooling device (12) is connected in the direction of flow (34) and which the heat protection device (26) encloses. Exhaust gas cooling device (10) after claim 6 , characterized in that the cooling device (12) and the heat protection device (26) are each materially connected to the inlet funnel (32) at mutually spaced regions. Exhaust gas cooling device (10) after claim 7 , characterized in that the cooling device (12) and/or the heat protection device (26) are soldered to the inlet funnel (32). Exhaust gas cooling device (10) according to one of the preceding claims, characterized in that the heat protection device (26) is provided by a heat protection plate. Motor vehicle with an exhaust gas cooling device (10) according to one of the preceding claims.

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