The present invention relates to an exhaust-gas recirculation cooler for an internal combustion engine system and to an internal combustion engine system having such an exhaust-gas recirculation cooler.

To increase the efficiency of internal combustion engines and/or to improve the environmental balance of internal combustion engines, it is known for some of the exhaust gas generated during operation of the internal combustion engine to be supplied to the internal combustion engine. In an associated internal combustion engine system, this customarily occurs by tapping some of the exhaust gas from an exhaust-gas system of the internal combustion engine. On account of the high temperature of the exhaust gas to be recirculated, it is desirable and/or necessary to cool the exhaust gas to be recirculated before it is recirculated to the internal combustion engine. For this purpose, use is made of exhaust-gas recirculation coolers which customarily have a heat exchanger with a housing. Exhaust gas on the one hand and coolant on the other hand flow through the housing and hence also through the heat exchanger, with the result that heat exchange occurs between the coolant and the exhaust gas during operation and the exhaust gas is cooled.

The object with which the present invention is concerned, for an exhaust-gas recirculation cooler of the type stated at the outset and for an internal combustion engine system having such an exhaust-gas recirculation cooler, is that of specifying improved or at least other embodiments which are distinguished in particular by a reduced installation space requirement and/or improved efficiency.

This object is achieved according to the invention by the subject matter of the independent claims. Advantageous embodiments form the subject matter of the dependent claims. The present invention is based on the general idea of providing, in an exhaust-gas recirculation cooler for an internal combustion engine system, the exhaust-gas recirculation cooler with at least one flange which serves for fluidically connecting the exhaust-gas recirculation cooler to the internal combustion engine system, and of providing the at least one flange with corresponding openings for the exhaust gas and for the coolant, wherein at least one of the associated openings is arranged in a housing of a heat exchanger of the exhaust-gas recirculation cooler on the side of the housing that faces the openings of the flange. It is thus possible in particular for constituent parts of the exhaust-gas recirculation cooler for the fluidic connection of the associated openings to be arranged in an installation space-saving manner and/or to be reduced. Thus, on the one hand, the overall installation space requirement of the exhaust-gas recirculation cooler is reduced and, on the other hand, the fluid paths are shortened, with the result that corresponding pressure losses and/or thermal losses are reduced. The reduction in said losses leads to an increased efficiency of the exhaust-gas recirculation cooler.

In accordance with the concept of the invention, the exhaust-gas recirculation cooler has the heat exchanger with the housing and at least one flange. An exhaust-gas path of exhaust gas and a coolant path of coolant lead, fluidically separated from one another, through the heat exchanger, with the result that, during operation, heat exchange occurs between exhaust gas and coolant and therefore cooling of the exhaust gas occurs. The at least one flange is spaced apart from the housing, in particular being separate from the housing. The at least one flange has two spaced-apart exhaust-gas openings through which the exhaust gas path leads. With preference, one of the exhaust gas openings of the at least one flange serves for supplying exhaust gas to the heat exchanger, and the other exhaust-gas opening serves to remove exhaust gas from the heat exchanger. The exhaust-gas openings of the flange, also referred to hereinbelow as flange exhaust-gas openings, are assigned associated exhaust-gas openings of the housing, which are also referred to hereinbelow as housing exhaust-gas openings. That is to say that the housing has an associated housing exhaust-gas opening for the respective flange exhaust-gas opening, the exhaust-gas path leading through the respective exhaust-gas opening. The at least one flange further has two coolant openings which are spaced apart from one another and from the flange exhaust-gas openings. With preference, one of the coolant openings of the at least one flange serves for supplying coolant to the heat exchanger, and the other coolant opening serves for removing coolant from the heat exchanger. The respective coolant opening of the flange, also referred to hereinbelow as flange coolant openings, is assigned an associated coolant opening on the housing, also referred to hereinbelow as housing coolant opening. That is to say that the housing has an associated housing coolant opening for the respective flange coolant opening. Here, the coolant path leads through the respective coolant opening. According to the invention, there is provision that at least one of the housing coolant openings is arranged on the side of the housing that faces the associated flange coolant opening.

The at least one flange of the exhaust-gas recirculation cooler advantageously also serves for mechanically mounting the exhaust-gas recirculation cooler on the internal combustion engine system. For this purpose, the at least one flange can have connection openings which are separate from the exhaust-gas openings and coolant openings.

The at least one flange of the exhaust-gas recirculation cooler can have any desired shape in principle. Advantageously, the at least one flange has a planar and/or flat shape. This allows simple mounting of the exhaust-gas recirculation cooler on the internal combustion engine system, on the one hand, and leads, on the other hand, to a reduced installation space requirement. The housing of the heat exchanger advantageously forms an outer lateral surface of the heat exchanger, preferably of the exhaust-gas recirculation cooler. It is thus possible in particular to produce the exhaust-gas recirculation cooler to be more compact and/or to shorten the coolant path, with the result that the efficiency of the exhaust-gas recirculation cooler is increased.

It is advantageous if the housing delimits the exhaust gas path and/or the coolant path.

In preferred embodiments, at least one of the flange coolant openings is fluidically connected to the associated housing coolant opening via a connection body. That is to say in particular that the flange coolant opening and the associated housing coolant opening do not directly adjoin one another. The coolant path thus leads through the connection body. Here, the connection body is arranged between the flange coolant opening and the associated housing coolant opening and is fixed to the housing and the flange. The connection body allows a simplified fluidic connection between the associated flange coolant opening and the associated housing coolant opening and is compact by virtue of the arrangement between the associated coolant openings.

It is advantageous if the respective flange coolant opening is fluidically connected to the associated housing coolant opening via an associated connection body. Moreover, the heat exchanger with the housing can be held on the corresponding internal exhaust engine via the connection body. That is, the connection body can also act as a bracket for holding the heat exchanger with the housing on the corresponding internal exhaust engine. In this way, vibration transfer between the internal exhaust engine and the heat exchanger is reduced and/or the total number of required components is reduced. The respective connection body can have any desired shape and/or size in principle.

In particular, it is conceivable for at least one of the connection bodies to be formed as a tubular body which extends substantially, preferably entirely, rectilinearly, that is to say without inclinations and/or bendings. This, too, leads to a compact design and/or an increased efficiency of the exhaust-gas recirculation cooler.

Embodiments which prove advantageous are those in which at least one of the connection bodies, advantageously the respective connection body, has a base with a base opening, a collar projecting from the base, and an open side surrounded by the collar and spaced apart from the base. The connection body is thus trough-shaped or formed in the manner of a trough. Here, the open side of the connection body covers the associated flange coolant opening, additionally being in particular in alignment therewith, whereas the base opening covers the associated housing coolant opening, in particular being in alignment therewith. Here, the open side advantageously bears against the flange, and the base bears against the housing. This allows a particularly compact design of the exhaust-gas recirculation cooler, on the one hand, and/or a simplified realization of a fluid-tight connection between the flange coolant opening and the associated housing coolant opening. The trough-shaped design of the connection body also allows the coolant to be introduced in a simplified manner into the housing and thus into the heat exchanger and/or to be removed in a simplified manner from the housing or the heat exchanger. Of course, a converse arrangement of the connection body is also conceivable in such a way that the open side covers the associated housing coolant opening, in particular being in alignment therewith, whereas the base bears against the flange, and the base opening covers the associated flange coolant opening, in particular being in alignment therewith. In principle, at least one of the flange coolant openings can be arranged in alignment with the associated housing coolant opening. It is thus possible to shorten the coolant path and/or to produce the associated connection body in a more compact manner.

It is also conceivable for at least one of the flange coolant openings and the associated housing coolant opening to be arranged facing one another but offset with respect to one another. This makes possible in particular an improved supply of the coolant to the heat exchanger or an improved removal of the coolant from the heat exchanger.

In principle, the exhaust-gas recirculation cooler can have a single flange which has all the exhaust-gas openings and coolant openings.

Preferred embodiments are those in which the exhaust-gas recirculation cooler has two flanges which are spaced apart from one another, wherein the respective flange has one of the flange coolant openings and/or one of the flange exhaust- gas openings, preferably one of the flange coolant openings and one of the flange exhaust-gas openings. This makes possible a simplified fluidic connection of the exhaust-gas recirculation cooler with the internal combustion engine system and/or a simplified mounting of the exhaust-gas recirculation cooler on the internal combustion engine system. Furthermore, it is possible in this way for the supply and the removal of coolant and exhaust gas to and from the heat exchanger to be better separated from one another, with the result that the exhaust-gas recirculation cooler can be mounted on the internal combustion engine system in a simplified manner.

The housing of the heat exchanger can have any desired shape in principle. Preferred embodiments are those in which the housing is parallelepipedal. This leads in turn to a compact design of the exhaust-gas recirculation cooler and/or allows a simple production of the exhaust-gas recirculation cooler. It is furthermore possible in this way for the fluidic connections between the exhaust-gas recirculation cooler and the remainder of the internal combustion engine system to be implemented in a simplified manner.

Preferred embodiments are those in which the two housing coolant openings are arranged on that side of the housing which faces the associated flange coolant openings. It is particularly preferred if the two housing coolant openings are arranged on the same side of the housing. This leads to a particularly compact and simple design of the exhaust-gas recirculation cooler.

Particularly in the case of a parallelepipedal shape of the housing, it is preferred if the two housing coolant openings are arranged on the same side of the housing, this side also being referred to hereinbelow as lower side. The lower side is thus particularly that side of the housing which faces the two flange coolant openings.

By contrast, at least one of the housing exhaust-gas openings can be arranged on an end side of the housing that extends transversely or at an inclination to the lower side. Here, the end side can be open in order thus to form the corresponding housing exhaust-gas opening. It is particularly preferred if mutually opposite end sides of the housing are each provided with one of the housing exhaust-gas openings, in particular forming such a housing exhaust gas opening through an open design.

In principle, the housing can be produced in an integral and coherent manner, that is to say from the same coherent material. In particular, the housing can be produced from a strip or a metal sheet by forming and/or connection. It is also conceivable to form the housing from half-shells. Accordingly, the housing has two housing half-shells which are fixed to one another. It is particularly preferred here if one of the housing half-shells has the two housing coolant openings. A simple production of the exhaust-gas recirculation cooler is thus possible. The housing half-shell having the housing coolant openings thus in particular has the lower side of the housing and can therefore also be referred to as lower shell, and is fixed to the other housing half-shell, which can accordingly be referred to as upper shell.

Embodiments which have proved advantageous are those in which one of the housing half-shells has a step in which the other housing half-shell engages, in particular by a peripheral edge, and on which the other housing half-shell lies. Simple fixing of the housing half-shells is thus possible. In addition, leakages in the fixing region between the half-shells are thus prevented or at least reduced.

In principle, the different constituent parts of the exhaust-gas recirculation cooler can be connected to one another and/or fixed to one another in any desired manner. In particular, it is possible for the constituent parts of the exhaust-gas recirculation cooler, for example the housing, the at least one connection body and the at least one flange to be fixed to one another in an integrally bonded manner, in particular by brazing or welding.

In the case of the end-side arrangement of the at least one housing exhaust-gas opening, a diffusor-like fluidic connection, in particular a diffusor, can be provided between the housing exhaust-gas opening and the associated flange exhaust-gas opening. The diffusor can be produced in a shell design.

Alternatively, at least one of the diffusors can be a constituent part of the housing. In this case, at least one of the housing exhaust-gas openings is preferably formed in the diffusor. It is possible for at least one of the diffusor to be built by said housing half-shells.

In this case, a part, in particular a half, of the diffusor is part of the corresponding housing half-shell. This leads to an enhanced rigidity and a reduced weight of the exhaust gas cooler.

It will be understood that, in addition to the exhaust-gas recirculation cooler, an associated internal combustion engine system also belongs to the scope of this invention. In the internal combustion engine system, the exhaust-gas recirculation cooler is fluidically connected via the at least one flange to the internal combustion engine system, preferably being mounted thereon, in particular on the internal combustion engine, for example on an engine block of the internal combustion engine.

It is preferable if corresponding fluid lines for the exhaust gas and/or for the coolant lead through the engine block.

Further important features and advantages of the invention will emerge from the subclaims, from the drawings and from the associated description of the figures with reference to the drawings.

It goes without saying that the features which are mentioned above and those still to be explained below can be used not only in the respectively specified combination but also in other combinations or on their own, 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, with identical reference signs relating to identical or similar or functionally identical components.

In the drawings Figure 1 schematically shows a highly simplified, circuit diagram-like illustration of an internal combustion engine system with an exhaust- gas recirculation cooler,

Figure 2 schematically shows an isometric view of the exhaust-gas recirculation cooler,

Figure 3 schematically shows an exploded illustration of the exhaust-gas recirculation cooler,

Figure 4 schematically shows a section through the internal combustion engine system in the region of the exhaust-gas recirculation cooler,

Figure 5 schematically shows an isometric view of a connection body of the exhaust-gas recirculation cooler,

Figure 6 schematically shows an exploded illustration of a housing of the exhaust-gas recirculation cooler in another exemplary embodiment,

Figure 7 schematically shows a section through the exhaust-gas recirculation cooler from figure 6.

An internal combustion engine system 1, as is illustrated in a highly simplified manner and in the manner of a circuit diagram in figure 1 , has an internal combustion engine 2. The internal combustion engine system 1 also has a fresh- air system 3 by means of which the internal combustion engine is supplied with air which is burnt with a fuel during operation of the internal combustion engine 2.

This gives rise to exhaust gas, which is removed with the aid of an exhaust-gas system 4 of the internal combustion engine system 1. In order to be able to recirculate the exhaust gas of the internal combustion engine 2, the internal combustion engine system 1 has an exhaust-gas recirculation line 5 which fluidically connects the exhaust-gas system 4 to the fresh-air system 3. Here, an exhaust-gas path 6 of the exhaust gas extends through the exhaust-gas recirculation line 5. To cool the exhaust gas provided for recirculation, there is provided an exhaust-gas recirculation cooler 7 through which the exhaust-gas path 6 and a coolant path 8 of a coolant, fluidically separated from the exhaust-gas path 6, leads, with the result that heat exchange between the exhaust gas and the coolant occurs during operation and the exhaust gas is cooled.

Figures 2 and 3 show the exhaust-gas recirculation cooler 7, with figure 2 showing an isometric view and figure 3 showing an exploded illustration of the exhaust-gas recirculation cooler 7.

The exhaust-gas recirculation cooler 7 has a heat exchanger 9 for cooling exhaust gas, with a section through the internal combustion engine system 1 in the region of the heat exchanger 9 being visible in figure 4.

The heat exchanger 9 has a housing 10 through which the exhaust gas path 6 and the coolant path 8 extend so as to be fluidically separated from one another. In the example shown, the heat exchanger 9 has a tube bundle 11 , which has a plurality of spaced-apart tube bodies 12, wherein figure 3 shows only one of the tube bodies 12. Here, the exhaust-gas path 6 leads through the tube bodies 12, whereas the coolant path 8 extends between the tube bodies 12, with the result that the tube bodies 12 allows a fluidically separated heat exchange between the exhaust gas and the coolant. As can be gathered particularly from figure 4, a ribbed structure 13 for increasing the heat-transferring area and/or for generating turbulence can be arranged within the respective tube body 12 of the tube bundle 11. The exhaust-gas recirculation cooler 7 further has at least one flange 14 which is spaced apart from the heat exchanger 9, in particular from the housing 10, with two such flanges 14 being provided in the example shown, said flanges 14 being spaced apart from one another and being arranged substantially in the same plane. The respective flange 14 has a flange exhaust-gas opening 15 and a flange coolant opening 16 spaced apart from the flange exhaust-gas opening 15. Here, the exhaust-gas path 6 leads through the respective flange exhaust-gas opening 15, whereas the coolant path 8 leads through the respective flange coolant opening 16. In the example shown, one of the flange exhaust-gas openings 15 serves to supply exhaust gas to the heat exchanger 9, and the other flange exhaust-gas opening 15 serves to remove exhaust gas from the heat exchanger 9. One of the flange coolant openings 16 serves for supplying the coolant to the heat exchanger 9, whereas the other flange coolant opening 16 serves to remove the coolant from the heat exchanger 9. For the respective flange exhaust-gas opening 15, the housing 10 of the heat exchanger 9 has an associated exhaust gas opening 17, also referred to hereinbelow as housing exhaust-gas opening 17. The housing 10 of the heat exchanger 9 further has, for the respective flange coolant opening 16, an associated coolant opening 18, which is also referred to hereinbelow as housing coolant opening 18 (see also figure 6). As can be gathered from figures 2 to 4, at least one of the housing coolant openings 18 is arranged on the side of the housing 10 that faces the associated flange coolant opening 16. In the example shown, the two housing coolant openings 18 are arranged on that side of the housing 10 which faces the associated flange coolant opening 16. Since the two flanges 14 and the associated flange coolant opening 16 are arranged on the same side of the housing 10 in the example shown, the two housing coolant openings 16 are thus also arranged on the same or common side 19 of the housing 10.

In the example shown, the housing 10 has a substantially parallelepipedal design. Here, the two housing coolant openings 18 are arranged on, in particular formed in, the common side 19 of the housing 10, also referred to hereinbelow as lower side 19. By contrast, the housing exhaust-gas openings 17 are arranged on end sides 20 of the housing which extend transversely to the lower side 19 and which form the longitudinal end sides of the parallelepipedal housing shown. In the example shown, the end sides 20 are completely open and thus each form one of the housing exhaust-gas openings 17. As can be gathered from figure 3, for example, the end sides 20 can have arranged thereon a respective grid-shaped tube-receiving structure 21 in which the tube bodies 12 of the tube bundle 11 are received. On the side of the respective tube-receiving structure 21 that faces away from the tube bundle 11 there is provided a diffusor 22 which is separate from the housing and which fluidically connects one of the housing exhaust-gas openings 17 to the associated flange exhaust-gas opening 15, with the result that the exhaust-gas path 16 extends through the respective diffusor 22. On the side of the respective flange 14 that faces away from the heat exchanger 9 there can be provided a seal 23, in particular a sealing flange 24.

In the example shown, the respective housing coolant opening 18 is fluidically connected to the associated flange coolant opening 16 with the aid of a connection body 25 which is separate from the housing 10, the connection bodies 25 in the example shown being identically formed. One of the connection bodies 25 is illustrated separately in figure 5. The connection body 25 is accordingly of trough shaped design and has an open side 26, a projecting collar 27 surrounding the open side 26, and a base 28 with a base opening 29, said base being spaced apart from the open side 26 and adjoining the collar 27. The base opening 29 extends only over part of the base 28 and is smaller than the open side 26. On the side of the collar 27 that faces away from the base 28, the connection body 25 additionally has a peripheral shoulder 30 which projects substantially parallel to the base 28. Figures 2 to 5, when viewed together, show that the respective connection body 25 bears flat on the associated flange 14 by way of the shoulder 30 in such a way that the open side 26 covers the flange coolant opening 16 and is spaced apart from the flange exhaust-gas opening 15. In addition, the base 28 bears flat against the housing 10, in particular against the lower side 19, in such a way that the base opening 29 covers and is thus aligned with the associated housing coolant opening 18. Here, the respective flange coolant opening 16 and the associated housing coolant opening 18 are arranged so as to be offset with respect to one another.

The constituent parts of the exhaust-gas recirculation cooler 7 which are separate from one another can be connected to one another or fixed to one another in an integrally bonded manner. In particular, these constituent parts are brazed to one another. The respective flange 14 and the associated connection body 25 and also the respective connection body 25 and the housing 10 are advantageously fixed to one another in an integrally bonded manner, in particular by brazing.

As can be gathered in particular from figures 2 and 3, the housing 10 of the heat exchanger 9 is produced in one piece or integrally. By contrast, the respective diffusor 22 in the example shown in figures 2 to 4 is designed in the form of half shells and thus has a lower diffusor half-shell 31 and an upper diffusor half-shell 32. The respective lower diffusor half-shell 31 has a diffusor stub 33 which forms a plug connection with a flange exhaust-gas stub 34 of the associated flange exhaust-gas opening 15, the flange exhaust-gas stub 34 surrounding the flange exhaust-gas opening 16 and projecting therefrom in the direction of the associated diffusor 22.

Figures 6 and 7 show another exemplary embodiment of the exhaust-gas recirculation cooler 7, with figure 6 showing only an exploded illustration of the housing 10 of the heat exchanger 9. Figure 7 shows a section through the exhaust-gas recirculation cooler 7.

This exemplary embodiment differs from the exemplary embodiment shown in figures 2 to 4 in that the housing 10 has two housing half-shells 35, 36, namely a lower housing half-shell 35, which has the housing coolant openings 18 and therefore also the lower side 19, and an upper housing half-shell 36. In the example shown, the diffusors 22 are constituent parts of the housing 10 and are formed by the housing half-shells 35, 36, with the result that the respective housing exhaust-gas opening 15 is arranged in the region of the diffusor 22, in particular surrounded by the associated diffusor stub 33. The housing exhaust-gas openings 17 can thus also, as shown, be arranged on the lower side 19 of the housing 10.

One of the housing half-shells 35, 36, in the example shown the lower housing half-shell 35, can have at least one step 37. Figure 7 here shows a section through the exhaust-gas recirculation cooler 7 in the region of two of the steps 37, which can be arranged along the tube-receiving structure 21. Here, the other housing half-shell 35, 36, that is to say in the present case the upper housing half-shell 36, engages in the respective step 37 and bears against the step 37.

As can be gathered in particular from figure 4, the respective flange 14 also serves for mechanically mounting the exhaust-gas recirculation cooler 7 in the internal combustion engine system 1, in particular on an engine block 38 of the internal combustion engine 2. Here, fluid lines 39 can lead through the engine block 38, with only one such line 39 being visible in figure 4. The fluid lines 39 are provided for the exhaust gas or for the coolant, with the fluid line 39 visible in figure 4 serving to supply coolant to the exhaust-gas recirculation cooler 7. Therefore, the coolant path extends through the fluid line 39 visible in figure 4.

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