EP3514365A1

EP3514365A1 - Device for cooling an exhaust gas recirculation (egr) flow of an internal combustion engine

Info

Publication number: EP3514365A1
Application number: EP18152001.6A
Authority: EP
Inventors: Domenico PETRONIO; Vincenzo PIETRAFESA
Original assignee: FCA Italy SpA
Current assignee: Stellantis Europe SpA
Priority date: 2018-01-17
Filing date: 2018-01-17
Publication date: 2019-07-24

Abstract

A device for cooling an exhaust gas recirculation (EGR) flow of an internal combustion engine comprises a body (2) with an inlet (3) and an outlet (4) for the EGR flow, defining a circuit for the EGR flow, and two heat exchanger modules (5, 6) for cooling the EGR flow, arranged in series or in parallel in the circuit. The device comprises a primary by-pass passage (16) arranged in parallel with both heat exchanger modules (5, 6) and a single valve element (19) pivotally connected within the body (2) around an articulation axis (20), to direct the EGR flow through both heat exchanger modules (5, 6), or through only one of the heat exchanger modules (5), or only through the primary by-pass passage (16). The valve element includes two door portions (19A, 19B) extending from the articulation axis and rigidly connected to each other.

Description

Field of the invention

The present invention relates to devices for cooling an exhaust gas recirculation (EGR) flow of an internal combustion engine, of the type comprising:

a body with an inlet and an outlet for the EGR flow, defining a circuit for the EGR flow from said inlet to said outlet,
two heat exchanger modules for cooling the EGR flow, arranged in series or in parallel in said circuit for the EGR flow,
a primary by-pass passage arranged in said circuit for the EGR flow in parallel with both heat exchanger modules,
valve means arranged within said body and configured to direct the EGR flow through both said heat-exchanger modules, or through only one of said heat-exchanger modules, or only through said primary by-pass passage.

Prior art

A device of the type indicated above is described and illustrated in document US 8 528 529 B2 . In this known device, the valve means include three valves that are controllable according to the operating conditions of the engine to vary the degree of cooling to which the EGR flow is subjected. In particular, the device is able to operate in a "full cooling" condition, in a "partial cooling" condition, or in a condition in which the cooling function is excluded.
The aforesaid known device, however, has the disadvantage of having a relatively complex and consequently expensive structure and also involves a relatively complex control of its operation.

Object of the invention

The object of the present invention is to provide a device of the type indicated at the beginning of the present description that is characterized by an extremely simple and reliable structure during operation.
A further object of the invention is to achieve the aforesaid objective through a device that can be controlled in a simple and efficient way to vary the degree of cooling to which the EGR flow must be subjected.

Summary of the invention

In view of achieving this object, the invention relates to a device for cooling an exhaust gas recirculation (EGR) flow having all the characteristics indicated at the beginning of the present description, and further characterized in that the aforesaid valve means are constituted by a single valve element, pivotally connected within the aforesaid body of the device around an articulation axis, and including two door portions extending from said articulation axis and rigidly connected to each other, said valve element being configured to have:

a first operating position, in which the EGR flow is conveyed through both said heat exchanger modules,
a second operating position, in which the EGR flow is conveyed through only one of said heat exchanger modules, and
a third operating position, in which the EGR flow is only conveyed through said primary by-pass passage.

Thanks to the arrangement described above, the device according to the invention is able to control the degree of cooling of the EGR flow in a simple and efficient manner.
In a first embodiment, the device according to the invention is further characterized in that:

the two heat exchanger modules each have a respective inlet and a respective outlet, and are connected in series in a U-shaped arrangement, the upstream heat exchanger module, with reference to the direction of the EGR flow, having the inlet communicating with the inlet of said body, and the downstream heat exchanger module, with reference to the direction of the EGR flow, having the outlet communicating with the outlet of said body,
the device also comprises a secondary by-pass passage, connected in parallel with the downstream heat exchanger module, and
said valve element is arranged in such a way that the first of said door portions is configured to selectively close the inlet of said upstream heat exchanger module or the inlet of the primary by-pass passage, while the second of said door portions is configured for closing or opening the outlet of the secondary by-pass passage, in such a way that:
in the first operating position of the valve element, the first door portion closes the inlet of the primary by-pass passage and the second door portion closes the outlet of the secondary by-pass passage,
in the second operating position of the valve element, the first door portion closes the inlet of the primary by-pass passage and the second door portion opens the outlet of the secondary by-pass passage, and
in the third operating position of the valve element, the first door portion closes the inlet of the upstream heat exchanger module and the second door portion opens the outlet of the secondary by-pass passage.

In a second embodiment, the device according to the invention is further characterized in that:

the two heat exchanger modules each have a respective inlet and a respective outlet, and are connected in series in a U-shaped arrangement, the upstream heat exchanger module, with reference to the direction of the EGR flow, having the inlet communicating with the the inlet of said body, and the downstream heat exchanger module, with reference to the direction of the EGR flow, having the outlet communicating with the outlet of said body,
the device also comprises a secondary by-pass passage, connected in parallel with the upstream heat exchanger module, and
said valve element is arranged in such a way that:
- in the first operating position, it prevents the EGR flow from passing through the primary by-pass passage and through the secondary by-pass passage, and instead allows the EGR flow to pass through the upstream heat exchanger module and then through the downstream heat exchanger module,
- in the second operating position, the valve element prevents the EGR flow from passing through the primary by-pass passage and instead allows the EGR flow to pass through the secondary by-pass passage and then through the downstream heat exchanger module, and
- in the third operating position, the valve element prevents the EGR flow from passing through both said upstream heat exchanger module, and through the secondary by-pass passage, and only allows the EGR flow to pass through the primary by-pass passage.

According to another embodiment, the device according to the invention is further characterized in that:

the two heat exchanger modules each have a respective inlet and a respective outlet, and are connected in parallel, both heat exchanger modules having their respective inlets communicating with the inlet of said body and their respective outlets communicating with the outlet of said body, and
the valve element is arranged in such a way that:
- in the first operating position, it prevents the EGR flow from passing through the primary by-pass passage, and instead allows the EGR flow to pass through both heat exchanger modules,
- in the second operating position, the valve element prevents the EGR flow both from passing through the primary by-pass passage and from passing through one of said two heat exchanger modules, and
- in the third operating position, the valve element prevents the EGR flow from passing through both said heat exchanger modules, and only allows the EGR flow to pass through the primary by-pass passage.

Detailed description of some embodiments

Further characteristics and advantages of the invention will become apparent from the description that follows, with reference to the attached drawings, provided purely by way of non-limiting example, wherein:

Figures 1A, 1B are two schematic cross-sectional views showing two operating conditions of a device for cooling an exhaust gas recirculation (EGR) flow of an internal combustion engine, according to the prior art,
Figure 2 is a schematic cross-sectional view of another cooling device according to the prior art,
Figure 3 is a schematic cross-sectional view of another cooling device according to the prior art,
Figure 4 is a schematic cross-sectional view, on an enlarged scale, of the heat exchanger module forming part of the known device of Figure 3,
Figure 5 is a schematic cross-sectional view of another device according to the prior art, corresponding to Figure 3 of the document US 8 528 529 B2 ,
Figures 6A, 6B, 6C are schematic cross-sectional views that show a first embodiment of the device according to the invention in three different operating conditions, and
Figures 7, 8 and 9 are schematic cross-sectional views that show three additional embodiments of the device according to the invention.

In Figures 1A, 1B, the reference number 1 indicates - in its entirety - a conventional cooling device for the exhaust gas recirculation (EGR) flow of an internal combustion engine. The device 1 comprises a body 2 with an inlet connector 2A and an outlet connector 2B. The connectors 2A, 2B define an inlet 3 and an outlet 4 of a U-shaped path inside the device. This U-shaped path has its ends communicating with a chamber 7, in turn communicating with both the inlet 3 and the outlet 4. The U-shaped path has a forward portion that starts from the chamber 7 and a rearward portion that returns to the chamber 7. The forward portion passes through a first section 5 of a heat exchanger. The rearward portion passes through a second section 6 of the heat exchanger. Therefore, the recirculated gases that enter the device through the inlet 3 flow through the two sections 5, 6 of the heat exchanger in series, and then finally exit through the outlet 4.
Circulation of the EGR flow is controlled by a door valve 9, pivotally connected in 10 to the body of the device. The door valve 9 has a first operating position, illustrated in Figure 1A, in which it prevents direct communication between the inlet 3 and the outlet 4, so that the EGR flow is forced to flow through the first section 5 of the heat exchanger, and subsequently through section 6 of the heat exchanger, and then exit from the device through the outlet 4.
The door valve 9 has a second operating position, illustrated in Figure 1B, in which it obstructs the inlet of section 5 of the heat exchanger, so that the EGR flow passes directly from the inlet 3 to the outlet 4 without crossing sections 5, 6 of the heat exchanger.
In the known device described above, therefore, two different operating conditions can be obtained: a first operating condition (Figure 1A) in which the EGR flow passes through both sections 5, 6 of the heat exchanger, which cause the EGR flow to cool, and a second operating condition in which the EGR flow passes through neither of sections 5, 6, so that the cooling function is totally excluded.
Again, with reference to the known device of Figures 1A, 1B, sections 5, 6 of the heat exchanger are usually constituted by a body including a bundle of tubes, through which the EGR flow passes, and that are arranged in a chamber, through which a coolant flows, typically the coolant of the internal combustion engine. To this end, the heat exchanger is inserted into the part of the engine cooling circuit that is external to the engine.
Still with reference to the known arrangement, the door valve 9 is controlled by an actuator, for example, an electrically-operated actuator, which is - in turn - controlled by an electronic controller on the basis of signals indicative of the operating conditions of the engine, so as to enable or disable the cooling function of the EGR flow according to these operating conditions.
Figure 2 is a schematic cross-sectional view of another device according to the prior art. In this Figure, the common parts or those corresponding to those of Figures 1A and 1B are indicated by the same reference numbers. The main difference with respect to the known device of Figures 1A, 1B lies in the fact that in the case of Figure 2, the device has a configuration in line with the inlet 3 and the outlet 4 at opposite ends of the body 2. The body includes a duct 11 defining a by-pass passage 12, in parallel with a single heat exchanger 5. The door valve 9 is arranged adjacent to the inlet 3, and enables the EGR to flow selectively towards the heat exchanger 5 or towards the by-pass passage 12. The door valve 9 of the device of Figure 2 has a first operating position in which it completely obstructs the inlet of the by-pass passage 12, so as to enable the cooling function obtained by the passage of the flow in the exchanger 5, and a second operating position in which it obstructs access to the heat exchanger 5, so that the entire EGR flow passes into the by-pass passage 12 and the cooling function is excluded.
Figure 3 illustrates another device according to the prior art. In this Figure as well, the parts that are the same or corresponding to the preceding Figures are indicated by the same reference numbers.
The main difference with respect to the solution of Figure 2 lies in the fact that, in this case, a first door valve 9 is provided, which directs the EGR flow entering the device selectively towards the heat exchanger 5 or towards the by-pass passage 12, as well as a second door valve 13, pivotally connected in 14 to the body of the device, which is able to "obscure" a part of the bundle of tubes of the heat exchanger 5 with respect to the incoming EGR flow.
Figure 4 shows schematically the bundle of tubes 51 of the heat exchanger 5, immersed in a chamber 50 through which the engine coolant flows. In the position of the door valve 13 that is illustrated in Figure 3, the two lower rows of the tubes 51 of the heat exchanger 5 (whose cross-sections are darkened in Figure 4) are not accessible to the EGR flow entering the device, so that, in this condition, the cooling function is partialized. The door valve 9 instead, similarly to that of the solution in Figure 2, enables the entry of the EGR flow into the heat exchanger 5, or the complete exclusion thereof, diverting the inlet flow entirely through the by-pass passage 12. The solution illustrated in Figures 3, 4 is able to obtain some form of regulation of the cooling of the EGR flow, but has the drawback of being relatively complex in structure and control, and of causing undesired thermal stresses of the structure, due to the different thermal fields to which the different areas of the heat exchanger are subjected.
Figure 5 illustrates a known device from the document US 8 528 529 B2 . In Figure 5 as well, the common parts or those corresponding to those of the preceding Figures are indicated by the same reference numbers. Therefore, in Figure 5 as well, the number 1 indicates - in its entirety - a cooling device, including a body 2 with connectors 2A, 2B that define an inlet 3 and an outlet 4 for the circuit through which the EGR flow passes. This circuit includes a primary by-pass duct 16, which causes direct communication of the inlet 3 with the outlet 4, and a substantially U-shaped path, parallel to the primary by-pass duct 16, in which an upstream heat exchanger module 5, with reference to the direction of the EGR flow, and a downstream heat exchanger module 6, are arranged. In parallel with the heat exchanger module 6, a secondary by-pass passage 17 is also provided, which in the illustrated device causes direct communication of an intermediate chamber 18, arranged between the outlet 5B of the module 5 and the inlet 6A of the module 6, with the primary by-pass passage 16. The known device also comprises valve means including three poppet valves 90, 91, 92. The valve 90 controls the communication between the inlet 3 and the primary by-pass passage 16. The valve 91 controls the communication between the secondary by-pass passage 17 and the primary by-pass passage 16. The valve 92 controls the communication between the outlet 6B of the heat exchanger module 6 and the primary by-pass passage 16.
When the poppet valves 90, 91, 92 are in the positions illustrated in Figure 5, the EGR flow only passes through the upstream heat exchanger module 5, before flowing towards the outlet 4, which corresponds to a condition of partial cooling of the EGR flow. If both valves 90, 91 are closed and the valve 92 is open, the EGR flow is forced to flow through both heat exchanger modules 5, 6, which corresponds to a "full cooling" operating condition. Finally, if the two valves 91, 92 are closed, while the valve 90 is open, the cooling function is excluded, since the entire EGR flow passes directly from the inlet 3 to the outlet 4 through the primary by-pass duct 16. The complicated structure and complex control of the solution illustrated in Figure 5 is evident.
Figures 6A, 6B, 6C are schematic cross-sectional views that illustrate three different operating conditions of a first embodiment of the device according to the invention. In these Figures as well, the parts common or corresponding to those of the preceding Figures are indicated by the same reference numbers.
Also the embodiment of Figures 6A, 6B, 6C, indicated - in its entirety - by reference 1, comprises a body 2 with an inlet connector 2A, defining an inlet 3, and an outlet connector 2B defining an outlet 4. In this embodiment, two heat exchanger modules 5, 6 are arranged within the body 2. In particular, the modules 5, 6 are arranged in series along a U-shaped path, in parallel with a primary by-pass passage 16 that creates direct communication of the inlet 3 with the outlet 4. Moreover, the circuit for the EGR flow provides a secondary by-pass passage 17 that creates direct communication of a chamber 18 interposed between the outlet 5B of the upstream module 5, with reference to the direction of the EGR flow, and the inlet 6A of the downstream module 6, with the primary by-pass passage 16.
In the case of the invention, the valve means of the device comprise a single valve element 19 pivotally connected to the body 2 around an articulation axis 20 and including two door portions 19A, 19B extending from the articulation axis 20 and rigidly connected together.
Figure 6A shows the valve element 19 in a first operating position thereof, corresponding to the "full cooling" operating condition. In this position, the door portion 19A closes the inlet of the primary by-pass passage 16, while the door portion 19B closes the outlet of the secondary by-pass passage 17. In this condition, therefore, the EGR flow entering the device is forced to firstly flow entirely through the upstream heat exchanger module 5, and from there into the intermediate chamber 18 and then into the downstream heat exchanger module 6, then to exit from the device through the outlet 4.
Figure 6B shows the valve element 19 in a second operating position thereof, corresponding to the "partial cooling" operating condition. In this position, the door portion 19A closes the inlet of the primary by-pass passage 16, while the door portion 19B opens the outlet of the secondary by-pass passage 17. In this condition, therefore, the entire EGR flow entering the device passes through the upstream heat exchanger module 5 to then flow, at least mainly, through the secondary by-pass passage 17, given the lower resistance to flow offered by this passage with respect to the downstream heat exchanger module 6. Therefore, in this operating condition, at least a predominat part of the EGR flow only passes through the upstream heat exchanger module 5, and then flows directly to the outlet 4 passing through the secondary by-pass passage 17.
Figure 6C shows the valve element 19 in a third operating position, corresponding to the condition in which the cooling function is totally excluded. In this position, the door portion 19A closes the inlet of the upstream heat exchanger module 5, so that the entire EGR flow passes directly from the inlet 3 to the outlet 4 of the device. It can be seen that, in this position, the door portion 19B leaves the bypass passage outlet 17 open, but this is irrelevant for the correct operation of the device in this condition, since the EGR flow is naturally induced to flow towards the outlet 4.
Still with reference to Figure 6A, in this Figure, the following are shown in a purely schematic way: an electric motor M arranged to control the operating position of the valve element 19, and an electronic controller E, which controls the electric motor M according to signals S1, S2, S3, etc. that are indicative of parameters that define the operating conditions of the internal combustion engine. These parameters may include, for example, the temperature of the engine coolant, the temperature of the engine exhaust gases, the engine rotation speed, the engine load, etc. Of course, the electronic controller E controls the electric motor M according to techniques well known to those skilled in the art, also on the basis of a signal indicative of the operating position of the valve element 19, or of the electric motor M, or of any other element interposed in the transmission between the motor M and the valve element 19. These implementation aspects can be applied to all the embodiments of the invention, which are described and illustrated hereinafter.
Figure 7 illustrates a second embodiment of the device according to the invention. This embodiment is substantially similar to that of Figures 6A, 6B, 6C, except for an inversion of the inlet 3 and the outlet 4.
In Figure 7, a first operating position of the valve element 19 is marked with a continuous line, corresponding to the "full cooling" operating condition. In this position, the valve element 19, with its two door portions 19A, 19B prevents the EGR flow from passing through the primary by-pass passage 16 and through the secondary by-pass passage 17, and instead allows the EGR flow to pass through the upstream heat exchanger module 5 and then through the downstream heat exchanger module 6. In this condition, a baffle 21 of an inner wall of the device is configured to discourage a flow of gas towards the secondary by-pass duct 17, instead favoring the passage of the entire EGR flow through the downstream exchanger module 6.
Still with reference to Figure 7, a second operating position of the valve element 19 is marked with a dashed line, corresponding to the "partial cooling" operating condition. In this position, the valve element 19 prevents the EGR flow from passing through the primary by-pass passage 16, and instead allows the EGR flow to pass through the secondary by-pass passage 17 and then through the downstream heat exchanger module 6.
Still with reference to Figure 7, a third operating position of the valve element 19, corresponding to the total exclusion of the cooling function, is illustrated with a dashed and dotted line. In this operating position, the valve element 19 prevents the EGR flow from passing both through the upstream heat exchanger module 5 and through the secondary by-pass passage 17, and only allows the EGR flow to pass through the primary by-pass passage 16, so that it flows directly from the inlet 3 to the outlet 4.
Figure 8 illustrates another embodiment of the device according to the invention. In this embodiment, the two heat exchanger modules 5, 6 are connected in parallel in the forward portion of a U-shaped arrangement. The two inlets of the modules 5, 6, indicated by the references 5A, 6A, both communicate with the inlet 3 of the device. The two outlets of the two modules 5, 6, indicated by the references 5B, 6B both communicate with an intermediate chamber 18 which, in turn, communicates - through a rearward passage 180 of the U-shaped circuit - with the outlet 4 of the device.
In Figure 8, a first operating position of the valve element 19 is illustrated with a continuous line, corresponding to the "full cooling" operating condition. In this operating position, the valve element 19 prevents the EGR flow from passing through the primary by-pass passage 16, and instead allows the EGR flow to pass through both heat exchanger modules 5, 6. Therefore, in this condition, the EGR flow passes from the inlet 3, through both heat exchanger modules 5, 6, into the intermediate chamber 18 and from there it returns to the outlet 4 through the rearward passage 180.
In Figure 8, a second operating position of the valve element 19 is illustrated with a dashed line, corresponding to the "partial cooling" operating condition. In this operating position, the valve element 19 prevents the EGR flow both from passing through the primary by-pass passage 16, and from passing through both heat exchanger modules 5, 6. Therefore, in this condition, the EGR flow entering the device passes only through the heat exchanger module 5 and then flows through the intermediate chamber 18 and the rearward passage 180 into the outlet 4. In this condition, a baffle 21 of the part of the body 2 that separates the modules 5 and 6 tends to prevent a passage of the flow through the module 6.
Still with reference to Figure 8, a third operating position of the valve element 19, corresponding to the exclusion condition of the cooling function, is illustrated with a dashed and dotted line. In this position, the valve element 19 prevents the EGR flow from passing through both heat exchanger modules 5, 6, and only allows the EGR flow to pass through the primary by-pass passage 16. Therefore, in this condition, the EGR flow entering the device flows directly to the outlet without undergoing any cooling.
Figure 9 of the attached drawings shows another embodiment of the device according to the invention, which is entirely similar both structurally and functionally to the embodiment of Figure 8, except for the fact that it presents an in-line arrangement, with the inlet 3 and the outlet 4 arranged at two opposite ends of the body 2 of the device. In this case, the intermediate chamber 18 is in direct communication with the outlet 4. The rearward passage 180 is not provided, while the primary by-pass passage 16 is constructively implemented by means of a duct 160 that extends in parallel with the part of the body 2 of the device in which the two modules 5, 6 are arranged. Otherwise, the structure and operation of the device, and, in particular, the different operating positions of the valve element 19, are identical to what has been described and illustrated above for the embodiment of Figure 8.
As is clear from the above description, a fundamental concept common to all the embodiments of the present invention lies in the fact that the different operating conditions of the device ("full cooling", "partial cooling", and "no cooling") are controlled by means of a single valve element pivotally connected within the body of the device around an articulation axis and including two door portions extending from the articulation axis and rigidly connected to each other.
It should also be noted that in all the embodiments of the device according to the invention described in the present description (Figures 6A to 9), the two heat exchanger modules 5, 6 can be structurally equal or different (e.g. in relation to their dimensions such as length, cross-section, diameter of the tubes 51, etc.). Likewise, in all the embodiments described herein, the two heat exchanger modules 5, 6 can be inserted into the same cooling circuit or into two separate cooling circuits, e.g. containing cooling fluids with different characteristics and/or at different temperatures.
Of course, without prejudice to the principle of the invention, the details of construction and the embodiments may vary widely with respect to those described and illustrated purely by way of example, without departing from the scope of the present invention, as defined by the attached claims.

Claims

A device for cooling an exhaust gas recirculation (EGR) flow of an internal combustion engine, comprising:
- a body (2) with an inlet (3) and an outlet (4) for the EGR flow, defining a circuit for the EGR flow from said inlet to said outlet,

- two heat exchanger modules (5, 6) for cooling the EGR flow, arranged in series or in parallel in said circuit for the EGR flow,

- a primary by-pass passage (16) arranged in said circuit for the EGR flow in parallel with both heat exchanger modules (5, 6),

- valve means (19) arranged within said body (2) and configured to direct the EGR flow through both said heat exchanger modules (5, 6), or through only one of said heat exchanger modules (5), or only through said primary by-pass passage (16),
characterized in that said valve means consist of a single valve element (19) pivotally connected within said body of said device around an articulation axis (20) and including two door portions (19A, 19B) extending from said articulation axis and rigidly connected to each other, said valve element being configured to have:
- a first operating position, wherein the EGR flow is conveyed through both said heat exchanger modules (5, 6),

- a second operating position, wherein the EGR flow is conveyed through only one of said heat exchanger modules (5), and

- a third operating position, wherein the EGR flow is only conveyed through said primary by-pass passage (16).
A device according to claim 1, wherein:
- the two heat exchanger modules (5, 6) each have a respective inlet (5A, 6A) and a respective outlet (5B, 6B) and are connected in series in a U-shaped arrangement, the upstream heat exchanger module (5), with reference to the direction of the EGR flow, having the inlet (5A) communicating with the the inlet (3) of said body, and the downstream heat exchanger module (6), with reference to the direction of the EGR flow, having the outlet (6B) communicating with the outlet (4) of said body,

- the device also comprises a secondary by-pass passage (17), connected in parallel with the downstream heat exchanger module (6), and

- said valve element is arranged in such a way that the first of said door portions (19A) is configured to selectively close the inlet of said upstream heat exchanger module or the inlet of the primary by-pass passage, and the second of said door portions (19B) is configured for closing or opening the outlet of the secondary by-pass passage, in such a way that:

- in the first operating position of the valve element (19), the first door portion (19A) closes the inlet of the primary by-pass passage (16) and the second door portion (19B) closes the outlet of the secondary by-pass passage (17),

- in the second operating position of the valve element (19), the first door portion (19A) closes the inlet of the primary by-pass passage (16) and the second door portion (19B) opens the outlet of the secondary by-pass passage (17), and

- in the third operating position of the valve element (19), the first door portion (19A) closes the inlet of the upstream heat exchanger module (5).
A device according to claim 1, wherein:
- the two heat exchanger modules (5, 6) each have a respective inlet (5A, 6A) a respective outlet (5B, 6B) and are connected in series in a U-shaped arrangement, the upstream heat exchanger module (5), with reference to the direction of the EGR flow, having the inlet (5A) communicating with the the inlet (3) of said body, and the downstream heat exchanger module (6), with reference to the direction of the EGR flow, having the outlet (6B) communicating with the outlet (4) of said body,

- the device also comprises a secondary by-pass passage (17), connected in parallel with the upstream heat exchanger module, and

- said valve element (19) is arranged in such a way that:
- in the first operating position, it prevents the EGR flow from passing through the primary by-pass passage (16) and through the secondary by-pass passage (17), and instead allows the EGR flow to pass through the upstream heat exchanger module (5) and then through the downstream heat exchanger module (6),

- in the second operating position, the valve element (19) prevents the EGR flow from passing through the primary by-pass passage (16) and instead allows the EGR flow to pass through the secondary by-pass passage (17) and then through the downstream heat exchanger module (6), and

- in the third operating position, the valve element (19) prevents the EGR flow from passing through both said upstream heat exchanger module (5) and the secondary by-pass passage (17), and only allows the EGR flow to pass through the primary by-pass passage (16).
A device according to claim 1, wherein:
- the two heat exchanger modules (5, 6) each have a respective inlet (5A, 6A) and a respective outlet (5B, 6B) and are connected in parallel, both heat exchanger modules having their respective inlets (5A, 6A) communicating with the inlet (3) of said body and the respective outlets (5B, 6B) communicating with the outlet (4) of said body, and

- the valve element (19) is arranged in such a way that:
- in the first operating position, it prevents the EGR flow from passing through the primary by-pass passage (16), and instead allows the EGR flow to pass through both heat exchanger modules (5, 6),

- in the second operating position, the valve element (19) prevents the EGR flow both from passing through the primary by-pass passage (16) and from passing through one of said two heat exchanger modules (6), and

- in the third operating position, the valve element (19) prevents the EGR flow from passing through both said heat exchanger modules (5, 6), and only allows the EGR flow to pass through the primary by-pass passage (16).
A device according to claim 4, wherein the inlet (3) and the outlet (4) of the body (2) of the device are at the ends of a U-shaped arrangement.
A device according to claim 4, wherein the inlet (3) and the outlet (4) of the body (2) of the device are at two opposite ends of an in-line arrangement.