WO2020084628A1

WO2020084628A1 - Exhaust gas cooler arrangement

Info

Publication number: WO2020084628A1
Application number: PCT/IN2018/050684
Authority: WO
Inventors: Bhushan DAHAKE; Gabriele Herbold; Bernd Krämer; Predrag Panic; Timm RÖSCHMANN
Original assignee: Mahle International GmbH; Mahle Behr India Pvt Ltd
Current assignee: Mahle International GmbH; Mahle Behr India Pvt Ltd
Priority date: 2018-10-23
Filing date: 2018-10-23
Publication date: 2020-04-30
Anticipated expiration: 2021-04-23
Also published as: DE112018008099T5

Abstract

The present invention relates to an exhaust gas cooler arrangement (3) for cooling exhaust gas of an internal combustion engine (2) which has a housing (13) in which a cooler (7) for cooling the exhaust gas is accommodated. A cost-effective and installation-space-saving design of the cooler arrangement (3) and more efficient cooling are achieved by means of an inlet diffuser (19) of the cooler arrangement (3) which is attached on the inlet side of the housing (13) and has a metallic inner wall (22) and an outer wall (23) which is made of plastic. The invention also relates to an internal combustion engine system (1) having an internal combustion engine (2) and such a cooler arrangement (3).

Description

TITLE : EXHAUST GAS COOLER ARRANGEMENT

The present invention relates to an exhaust gas cooler arrangement for cooling exhaust gas of an internal combustion engine, which has a housing and a cooler which is accommodated in the housing. The invention also relates to an internal combustion engine having such a cooler arrangement.

While an internal combustion engine is operating, exhaust gas is produced which leaves the internal combustion engine at high temperatures. For a large number of applications it is therefore desirable to cool the exhaust gas using a cooler. In particular when exhaust gas is recirculated to the internal combustion engine, such cooling is desired in order to prevent or reduce damage to subsequent components, that is to say components on the downstream side, of an associated internal combustion engine system and/or in order to increase the density of the exhaust gas. In a corresponding exhaust gas cooler arrangement, the cooler for cooling the exhaust gas is usually accommodated in a housing. During operation, the exhaust gas flows through the housing and is cooled by the cooler. Owing to the increased temperatures in the exhaust it is customary, in particular on the inlet side of the cooler arrangement, to manufacture the cooler arrangement from metallic components, that is to say components which are manufactured from metal or from an alloy, in order to bring about resistance to the hot exhaust gas. This results in cost-intensive manufacture and/or a design of the cooler arrangement which increases the weight. At the same time, only limited installation spaces are available to such a cooler arrangement. This is the case, in particular, when the cooler arrangement is used in a motor vehicle in which the cooler arrangement is to be configured in a way which is as efficient in terms of installation space as possible.

The present invention is therefore concerned with the object of specifying, for an exhaust gas cooler arrangement for cooling exhaust gas of an internal combustion engine and for an internal combustion engine system having such a cooler arrangement, improved embodiments, or at least different embodiments, which are distinguished, in particular, by more economical manufacture and/or increased efficiency.

This object is achieved according to the invention by means of the subject matter of the independent claims. Advantageous embodiments are the subject matter of the dependent claims. The present invention is based on the general concept of providing in an exhaust gas cooler arrangement, also referred to below in abbreviated form as cooler arrangement, a diffuser which carries the exhaust gas to a cooler and to manufacture said diffuser from an outer wall which is made of plastic and a metallic inner wall. The use of the diffuser to feed the exhaust gas to the cooler gives rise to advantageous guidance of the flow of the exhaust gas to the cooler, with the result that the exhaust gas is cooled more efficiently. The configuration of the diffuser with the outer wall which is made of plastic and the metallic inner wall gives rise to a cost-effective configuration of the diffuser with at the same time a high level of heat resistance.

In accordance with the inventive concept, the cooler arrangement has a housing in which the cooler is accommodated. The cooler serves to cool exhaust gas which passes and/or flows through the cooler during operation. For this purpose, the housing has an inlet opening for letting exhaust gas into the housing and an outlet opening for letting exhaust gas out of the housing. The diffuser serves to feed exhaust gas to the inlet opening and therefore the cooler. Accordingly, the diffuser will be also referred to below as the inlet diffuser. The inlet diffuser is arranged on the inlet side of the housing and has a diffuser outlet and a diffuser inlet which is spaced apart from the diffuser outlet. The exhaust gas flows through the diffuser inlet into the diffuser and leaves it through the diffuser outlet. Accordingly, the diffuser outlet is fluidically connected to the inlet opening of the housing. According to the invention, the metallic inner wall of the inlet diffuser extends between the diffuser inlet and the diffuser outlet, in particular from the diffuser inlet as far as the diffuser outlet, and bounds a flow path of the exhaust gas through the inlet diffuser. That is to say during operation the inner wall is subjected to the exhaust gas. For this purpose, the inner wall is preferably embodied in a closed fashion such that it encloses the flow path. The outer wall which is manufactured from plastic is arranged on the side of the inner wall facing away from the flow path, with the result that the inner wall protects the outer wall against the exhaust gas. In this context, the inner wall surrounds the outer wall, preferably in a closed fashion along the flow path.

The term“metallic” is to be understood here as meaning manufactured from metal or from a metal alloy, in particular from steel. That is to say the inner wall of the inlet diffuser is manufactured from a metal or a metal alloy, for example from steel. Embodiments in which a gap, preferably an air gap, is provided at least in certain sections between the inner wall and the outer wall are to be considered advantageous. As a result, transmission of heat between the inner wall and the outer wall is reduced, with the result that the outer wall is subjected to relatively low temperatures. The outer wall can therefore be manufactured from fewer heat-resistant plastics and therefore more cost- effectively. The gap advantageously extends along the flow path and in the circumferential direction of the inlet diffuser, wherein the gap can be embodied in a closed fashion in the circumferential direction.

The direction information used here relates to the extent of the inlet diffuser. That is to say the terms radial and in the circumferential direction are to be understood with respect to the extent of the inlet diffuser. If the inlet diffuser therefore extends axially, it is to be understood that radially and in the circumferential direction with respect to this axial direction are meant.

The gap can have in principle any desired dimensions.

Embodiments in which a height of the gap which extends between the inner wall and the outer wall, also referred to below as gap height, is between 0.05 mm and 1.2 mm, in particular is 1.0 mm, have proven advantageous. This ensures sufficiently high thermal protection of the outer wall, wherein the inner diffuser is simultaneously efficient in terms of installation space.

Embodiments are preferred in which the gap is provided only in the region of the diffuser inlet. This is to say the outer wall is spaced apart from the inner wall in order to form the gap in the region of the diffuser inlet. In the The gap height can decrease here toward the diffuser outlet. The decreasing of the gap height can be, in particular continuous here. In particular, the outer wall is connected to the inner wall without a gap in the region of the diffuser outlet. In this context, use is made of the knowledge that the temperature of the exhaust gas decreases toward the diffuser outlet, with the result that a decreasing gap height toward the diffuser outlet is sufficient for the thermal protection of the outer wall. In addition, mechanical stabilization of the inlet diffuser is thus brought about in the region of the diffuser outlet.

The housing of the cooler arrangement can in principle be manufactured from any desired material. In advantageous embodiments, the housing is manufactured from plastic. The housing can therefore be manufactured in a cost-effective fashion and/or with reduced weight.

The housing which is manufactured from plastic also permits a simplified connection between the housing and the outer wall, wherein embodiments are preferred in which the outer wall is attached to the housing in a materially joined fashion. The outer wall is advantageously soldered to the housing. It is also conceivable to weld the outer wall to the housing. The outer wall of the inlet diffuser therefore forms part of the housing.

It is advantageous if the inner wall of the inlet diffuser is attached to the cooler, in particular in a materially joined fashion. It is conceivable to solder or to weld the inner wall to the cooler.

Embodiments in which the outer wall surrounds the inlet opening but is spaced apart radially therefrom are advantageous. In contrast, the inner wall is arranged in such a way that it encloses the inlet opening and adjoins the inlet opening radially. A design of the cooler arrangement which is efficient in terms of installation space is therefore implemented, the flow cross section of the diffuser outlet and of the inlet opening being maximized in said cooler arrangement.

The inner wall and/or the outer wall can each have any desired wall thicknesses which can vary along the extent of the inlet diffuser.

Embodiments in which a wall thickness of the inner wall decreases toward the diffuser inlet are advantageous. In this context, use is made of the knowledge that the exhaust gas temperature decreases toward the diffuser outlet and increases toward the diffuser inlet, with the result that with the wall thickness which decreases toward the diffuser inlet, in particular in combination with the gap, it is possible to bring about improved compensation of deformations of the inner wall which may be of thermal origin.

The cooler arrangement preferably has a flange with which the cooler arrangement can be connected to the associated internal combustion engine or an exhaust system. The flange is advantageously attached to the inlet diffuser and surrounds the inlet diffuser in the region of the diffuser inlet. That is to say the inlet diffuser penetrates the flange. In this context, the outer wall is arranged between the flange and the inner wall. It is also advantageous if the outer wall is connected to the flange in a materially joined fashion, in particular by means of soldering.

Embodiments in which a plurality, preferably all, of the materially joined connections of the cooler arrangement are manufactured together are advantageous. That is to say, in particular, a plurality, preferably all, of the components of the cooler arrangement which are to be soldered to one another are soldered together. The same applies to components which are to be welded to one another.

In order to solder the components of the cooler arrangement which are to be soldered to one another, a soldering agent, in particular a nickel paste, is advantageously used. This permits a reliable and stable soldered connection between the components.

Of course, apart from the cooler arrangement, the scope of this invention also includes an internal combustion engine system having such a cooler arrangement and an internal combustion engine wherein the internal combustion engine system can be part of a motor vehicle.

The internal combustion engine system can have, apart from the internal combustion engine and the cooler arrangement, a fresh air system for feeding fresh air or a fresh air mixture to the internal combustion engine, and an exhaust system for carrying away exhaust gas from the internal combustion engine.

The cooler arrangement can be used to cool exhaust gas to be recirculated from the internal combustion engine. Accordingly, the cooler arrangement is advantageously a component of an exhaust gas recirculation device which feeds exhaust gas originating from the internal combustion engine to the internal combustion engine, in particular via the fresh air system.

The cooler of the cooler arrangement can in principle be configured in any desired way. The cooler is advantageously configured in such a way that exhaust gas can flow through it and it therefore cools the exhaust gas. It is conceivable, in particular, to provide a cooler which has pipes, in particular flat pipes, wherein, during operation exhaust gas flows through the pipes and a cooling fluid, for example air, flows around the pipes, so that an exchange of heat takes place between the cooling fluid and the exhaust gas, in order to cool this. The cooling fluid can also flow through the pipes and exhaust gas can flow around them. Further important features and advantages of the invention can be found in the dependent claims, the drawings and the associated description of the figures with reference to the drawings.

Of course, the features which are specified above and will be explained below can be used not only in the respectively specified combination but also in other combinations or alone without departing from the scope of the present invention.

Preferred exemplary embodiments of the invention are illustrated in the drawings and will be explained in more detail in the following description, wherein identical reference symbols relate to identical or similar or functionally identical components.

In the figures, in each case schematically:

Fig. 1 shows a highly simplified, circuit-diagram-like illustration of an internal combustion engine system having an exhaust gas cooler arrangement,

Fig. 2 shows an isometric view of the cooler arrangement, and

Fig. 3 shows a longitudinal section through the cooler arrangement. An internal combustion engine system 1 , as illustrated in highly simplified form and in the manner of a circuit diagram in figure 1 , has an internal combustion engine 2 in which exhaust gas is produced during operation. The internal combustion engine system 1 additionally has an exhaust gas cooler arrangement 3, also referred to below for short as cooler arrangement 3, for cooling the exhaust gas of the internal combustion engine 2.

In the example shown, the cooler arrangement 3 is part of an exhaust gas recirculation device 4 with which the exhaust gas is recirculated to the internal combustion engine 2. For this purpose, the exhaust gas recirculation device 4 branches off from an exhaust system 5 of the internal combustion engine system 1 which serves to carry away the exhaust gas which is produced in the internal combustion engine 2, and opens into a fresh air system 6 with which fresh air is fed to the internal combustion engine 2. It is also conceivable that the exhaust gas recirculation device 4 for branching off exhaust gas is connected directly to the internal combustion engine 2.

An example of a cooler arrangement 1 is illustrated in figures 2 and 3, wherein figure 2 shows an isometric view of the cooler arrangement 3, and figure 3 shows a longitudinal section through the cooler arrangement 3. In order to cool the exhaust gas, the cooler arrangement 3 has a cooler 7 which has a pipe bundle 8 with a plurality of pipes 9, flat pipes 10 in the example shown. A flow path 1 1 of the exhaust gas leads through the pipes 9 of the cooler 7. The pipes 9 are arranged in a flow path 12 of a cooling fluid, referred to below as cooling fluid flow path 12, in such a way that the cooling fluid flows around the pipes 9 fluidically separated from the flow path 1 1 of the exhaust gas. The cooling fluid can be coolant or air. The cooler 7 is accommodated in a housing 13 of the cooler arrangement 3, which housing 13 can be manufactured from plastic. The housing 13 is illustrated only partially in figures 2 and 3, specifically only in the region of an inlet opening 14 of the housing 13 and of an outlet opening 15 for letting exhaust gas out of the housing 13, through which outlet opening 15 the flow path 1 1 of the exhaust gas respectively leads. Arranged in the inlet opening 14 is a first receptacle plate 16 of the cooler 7 in which the pipes 9 are accommodated at the ends in such a way that the exhaust gas flows into the pipes 9 through the inlet opening 14. Arranged in the outlet opening 14 is a second receptacle plate 17 in which the other ends of the pipes 9 are accommodated in such a way that exhaust gas which flows out of the pipes 9 flows through the outlet opening 15 and leaves the housing 13. On the outlet side of the housing 13, the cooler arrangement 13 has a nozzle 18, referred to below as outlet nozzle 18, which is manufactured from plastic and fluidically connected to the outlet opening 15. The outlet nozzle 18 is connected in a materially joined fashion, in particular soldered, to the housing 13.

On the inlet side of the housing 13, the cooler arrangement 3 has a diffuser 19, also referred to below as inlet diffuser 19, which is fluidically connected to the inlet opening 14 via a diffuser outlet 20. The inlet diffuser 19 has a diffuser inlet 21 which is spaced apart from the diffuser outlet 20, wherein the inlet diffuser 19 extends between the diffuser inlet 21 and the diffuser outlet 20. In this context, an axial extent of the inlet diffuser 19 is assumed below. The flow path 1 1 of the exhaust gas leads through the diffuser inlet 21 and the diffuser outlet 20 as well as through the outlet nozzle 18.

The inlet diffuser 19 has an inner wall 22 which is manufactured from a metal or a metal alloy and extends from the diffuser inlet 21 to the diffuser outlet 20, and is embodied in a closed fashion in the circumferential direction 24 and bounds the flow path 1 1 of the exhaust gas in the inlet diffuser 19 such that the inner wall 22 enters into direct contact with the exhaust gas when exhaust gas flows through the inlet diffuser 19. The inlet diffuser 19 also has an outer wall 23 which is arranged on the side of the inner wall 22 facing away from the flow path 1 1 , is manufactured from plastic and extends from the diffuser inlet 21 to the diffuser outlet 20 and encloses the inner wall 22 in a closed fashion in the circumferential direction 24. The inner wall 22 and the outer wall 23 are each embodied in the form of a diffusers here. A gap 25, in particular an air gap 26, is formed between the inner wall 22 and the outer wall 23, wherein a height 27 of the gap 25, running between inner wall 22 and outer wall 23, decreases in the direction of the diffuser outlet 22 in the example shown, in such a way that the outer wall 23 bears without a gap against the inner wall 22 in the region of the diffuser outlet 20. The height 27 of the gap 25 is therefore greatest in the region of the diffuser inlet 21. In this context, the height 27 in the region of the diffuser inlet 21 is between 0.5 mm and 1.2 mm, and is, in particular, 1 .0 mm. It is also apparent that a wall thickness 28 of the inner wall 22 decreases toward the diffuser inlet 21 and increases toward the diffuser outlet 20.

The inlet diffuser 23 is introduced into a flange 20 on the inlet side, in such a way that the flange 29 encloses the diffuser inlet 21 in the circumferential direction 24. The outer wall 23 is arranged between the flange 29 and the inner wall 22. By means of the flange 29, the cooler arrangement 3 can be integrated fluidically and mechanically into the exhaust gas recirculation device 4 or can be connected to the internal combustion engine 2.

The outer wall 23 is connected in a materially joined fashion, in particular soldered, to the housing 13. In the example shown this is done by means of a radially protruding annular section 30, closed in the circumferential direction, of the outer wall 23, which annular section 30 encloses the inlet opening 14 and is spaced apart radially from the inlet opening 20. The annular section 30 lies on the housing 13 over a surface area. The outer wall 23 is also connected in a materially joined fashion, in particular soldered, to the flange 29. The inner wall 22 is connected in a materially joined fashion, in particular soldered, to the cooler 7, in particular to the first receptacle plate 16. The outlet nozzle 18 is connected in a materially joined fashion, in particular soldered, to the housing 13, and has for this purpose an annular connecting section 31 which surrounds the outlet opening 15 in the circumferential direction 24, is spaced apart therefrom radially and bears on the housing 13 over a surface area. The materially joined connections, in particular soldered connections are advantageously soldered in a common method, in particular, a common soldering process, wherein a soldering agent (not shown) can be used for this purpose.

Claims

We claim

1 . An exhaust gas cooler arrangement (3) for cooling exhaust gas of an internal combustion engine (2),

- having a housing (13), in which a cooler (7) for cooling the exhaust gas is accommodated and which has an inlet opening (14) for letting exhaust gas into the housing (13) and an outlet opening (15) for letting exhaust gas out of the housing (13),

- having an inlet diffuser (19) which is attached on the inlet side of the housing (13) and has a diffuser outlet (20) which is fluidically connected to the inlet opening (14), and a diffuser inlet (21 ), spaced apart from the diffuser outlet (20), for letting exhaust gas into the inlet diffuser (3),

- wherein the inlet diffuser (19) has a metallic inner wall (22) which

extends between the diffuser inlet (21 ) and the diffuser outlet (20) and bounds a flow path (1 1 ) of exhaust gas through the inlet diffuser (19), and an outer wall (23) which is made of plastic and which surrounds the inner wall (22) on the side facing away from the flow path (1 1 ).

2. The cooler arrangement as claimed in claim 1 ,

characterized in that

a gap (25) is provided at least in certain sections between the inner wall (22) and the outer wall (23).

3. The cooler arrangement as claimed in claim 2,

characterized in that

a height (27) of the gap (25) which extends between the inner wall (22) and the outer wall (23) is between 0.05 mm and 1.2 mm.

4. The cooler arrangement as claimed in claim 2 or 3,

characterized

- in that the outer wall (23) is spaced apart from the inner wall (22) in order to form the gap (25) in the region of the diffuser inlet (21 ), and

- in that the outer wall (23) and the inner wall (22) are connected to one another without a gap in the region of the diffuser outlet (20).

5. The cooler arrangement as claimed in one of claims 1 to 4,

characterized in that

the housing (13) is manufactured from plastic.

6. The cooler arrangement as claimed in claim 5,

characterized in that

in that the outer wall (23) is attached to the housing (13) in a materially joined fashion.

7. The cooler arrangement as claimed in one of claims 1 to 6,

characterized in that

the outer wall (23) surrounds the inlet opening (14) and is spaced apart from the inlet opening (14).

8. The cooler arrangement as claimed in one of claims 1 to 7,

characterized in that

the inner wall (22) surrounds the inlet opening (14) adjoins the inlet opening (14).

9. The cooler arrangement as claimed in one of claims 1 to 8,

characterized in that

a wall thickness (28) of the inner wall (22) decreases toward the diffuser inlet (21 ).

10. The cooler arrangement as claimed in one of claims 1 to 9, characterized

- in that the cooler arrangement (3) has a flange (29) which is attached to the inlet diffuser (19) and surrounds the diffuser inlet (21 ), and

- in that the outer wall (23) is arranged between the flange (29) and the inner wall (22).

1 1. An internal combustion engine system (1 ) having an internal

combustion engine (2), a fresh air system (6) for feeding fresh air to the internal combustion engine (2) and an exhaust system (5) for carrying away exhaust gas from the internal combustion engine (2) and having an exhaust gas recirculation device (4) for recirculating exhaust gas to the internal combustion engine (2), wherein the exhaust gas recirculation system (4) has an exhaust gas cooler arrangement (3) as claimed in one of the preceding claims.