EP2746561A1

EP2746561A1 - Conduit for a heat exchanger of an internal combustion engine EGR system

Info

Publication number: EP2746561A1
Application number: EP20120382528
Authority: EP
Inventors: Carlos Manuel CASTAÑO GONZÁLEZ
Original assignee: BorgWarner Inc
Current assignee: BorgWarner Inc
Priority date: 2012-12-24
Filing date: 2012-12-24
Publication date: 2014-06-25
Also published as: WO2014102227A1

Abstract

The present invention relates to a conduit for a heat exchanger of an internal combustion engine EGR (Exhaust Gas Recirculation) system. This conduit is particularly designed to withstand thermal fatigue due to stresses generated by expansion, primarily of the inner elements of the conduit intended for improving heat transfer, due to being embedded in resistant elements for fixing the ends of said conduits.

The invention uses resistant elements with a through hole allowing the passage of the cooling fluid therethrough to prevent these resistant elements from being subjected to an expansion such as that shown by the elements which are arranged inside the conduit. In addition to reducing thermal fatigue, this conduit allows solving problems associated with bubble formation at points where the boiling temperature is reached and particularly problems associated with essentially planar and horizontally arranged conduit configurations. In such configurations, the existence of through holes facilitates the passage of the bubbles that may be formed, preventing such bubbles from being lodged at one point which also facilitates thermal fatigue. Another object of this invention is the heat exchanger built using conduits with a through hole.

Description

Object of the Invention

The present invention relates to a conduit for a heat exchanger of an internal combustion engine EGR (Exhaust Gas Recirculation) system. This conduit is particularly designed for solving various technical problems which include withstanding internal pressure when the section is a non-circular section, or withstanding thermal fatigue due to the stresses generated by expansion, primarily of the inner elements of the conduit intended for improving heat transfer, due to being embedded in resistant elements for fixing the ends of said conduits.
The invention uses resistant elements with a through hole allowing the passage of the cooling fluid therethrough to prevent these resistant elements from being subjected to an expansion such as that shown by the elements which are arranged inside the conduit.
In addition to the preceding technical problems such as reducing thermal fatigue, this conduit allows solving problems associated with bubble formation and accumulation at points where the boiling temperature is reached and particularly problems associated with essentially planar and horizontally arranged conduit configurations. In such configurations, the existence of through holes facilitates the passage of the bubbles that may be formed, preventing such bubbles from being lodged at one point, which also facilitates thermal fatigue.
Another technical problem solved by the invention when it is part of a heat exchanger is that it allows modifying coolant liquid flow distribution given that the passage therethrough is possible.
Another object of this invention is a heat exchanger built using conduits with a through hole.

Background of the Invention

Exchangers of EGR systems installed in an internal combustion engine are exchangers intended for cooling the gas coming from the combustion of the mixture of a combustion agent and fuel for its partial reintroduction into the intake, reducing the oxygen content in the mixture.
Combustion gases are at very high temperatures, typically of the order of 600-800°C, and are cooled using a coolant liquid which is usually the engine cooling liquid with temperatures of about 90°C.
Heat exchangers suitable for cooling the EGR exhaust gases are formed by groups of conduits located inside a shell. The shell is closed at two ends and has an inlet and an outlet for the passage of the coolant liquid covering the outer surface of the conduits. The conduits are primarily fixed at their ends to resistant elements for closing the ends of the shell by embedding the perimetral area of the conduit in said resistant element for closing the shell.
The objective of the heat exchanger is to transfer heat from the EGR gas to the coolant liquid to reduce its temperature. The way to improve heat transfer between the gas and the coolant liquid is by means of incorporating fins and elements with a large surface area, for example fins, which increase the heat transfer from the gas to said element, and these elements with a large surface area in turn transfer heat to the inner surface of the conduit. This surface is externally cooled by the coolant liquid dissipating the transferred heat.
Elements which increase the contact surface area and are located inside the conduit are subjected to very high temperature gradients. If a common conduit configuration with a very flattened section is considered, the element which increases the contact surface area is a structural element connecting the two walls of the conduit between two nearby points. In this small gap, the points of the structural element contacting the wall are at temperatures close to the temperature of the coolant liquid, whereas the points located in the center are at the temperature of the EGR gas. _The central area being at the temperature of the gas results in a significant expansion which tends to occur from inside the cooling conduit.
As mentioned, the conduits are fixed at their end by means of an embedment on the outside thereof. This embedment prevents expansion of the conduit, and the structural element for closing the shell is sufficiently covered by the coolant liquid so as to not experience significant expansions. If the element which increases the contact surface area arranged inside the conduit is close to the embedment of the end of the conduit, its expansion causes the conduit to expand from the inside generating significant stresses due to the embedment close to the conduit which in turn prevents that expansion. These stresses result in the premature failure of the exchanger due to thermal fatigue.
A second problem for some heat exchangers of EGR systems is the existence of vapor bubbles anchored in places that cannot be removed by circulating the coolant liquid.
This is the case of heat exchangers which use inner conduits with a very flattened section and which, due to space restrictions, must have horizontally oriented conduits. When a point reaching the boiling temperature appears inside these exchangers and a bubble is formed, the bubble tends to circulate due to coolant liquid convection and at the same time move upwards due to flotation forces. Nevertheless, the horizontal arrangement of the inner conduits means that the tendency of the bubble to float places said bubble or bubbles below one of the conduits and that the bubble does not move from that point or that area. When the bubble has no way out or when the convection of the coolant liquid is low, places below one or more conduits where the gas bubbles accumulate at a high temperature appear. As a result, the area with vapor bubble accumulation is no longer suitably cooled.
A third problem with conduits having a non-circular section such as those referred to as hybrid conduits, for example conduits having an oval-shaped section, is that the internal pressure generates forces which tend to force an expansion which the walls of the conduit cannot withstand. If the section is a non-circular section, the thin planar plates cannot withstand this expansion force and result in conduit deformation.
A fourth problem of the state of the art in heat exchangers is the lack of design freedom in establishing the coolant liquid flow when the section of the conduits is large. Conduits with a wide flattened section behave like a large plate preventing passage therethrough, making correct cooling of some parts of the exchanger difficult.
The present invention particularly solves the first and second problems because it has resistant elements with a through hole allowing the passage of the coolant liquid therethrough, preventing expansions which generate stresses in the embedment of the conduit, and additionally, the bubbles which may appear on one side of the conduit do not accumulate on that side because they can pass from one side to another through the through holes.
The invention likewise solves the third problem in those cases in which the conduit has a non-circular section, for example a flattened section, where the arrangement of the resistant elements, for example along the length connecting opposite points, gives rise to a reinforcement allowing the conduit to withstand high internal pressures without causing deformation.
The invention also solves the fourth problem according to embodiments of the invention when the resistant elements with a through hole are used as a means for the passage of the main coolant liquid flow in a direction transverse to the group of conduits.
The foregoing and other additional problems are solved by means of the claimed invention as well as by means of different particular embodiments.

Description of the Invention

The invention consists of a conduit particularly envisaged for a heat exchanger of an internal combustion engine EGR system where the heat exchanger allows heat exchange between a first fluid, preferably an EGR gas to be cooled, intended for circulating inside the conduit, and a second fluid, preferably a coolant liquid, intended for circulating on the outside of said conduit without the two fluids contacting one another.
The conduit extends substantially according to a longitudinal direction X-X' between an inlet and an outlet and has an inner section S, extending in a plane perpendicular to the longitudinal direction X-X' where:

the conduit formed, among others, by a limiting wall between the inside and the outside thereof is traversed by one or more extending structural elements connecting two different points of the limiting wall of the conduit where these structural elements have a through hole such that they allow the passage of the second fluid through said structural element for its cooling.

As described in the section dedicated to the state of the art, the conduits of a heat exchanger (particularly those of an EGR system) fixed by means of an embedment at the end thereof experience thermal fatigue due to the expansion of the inner elements which are located close to the embedment and are subjected to expansion. The conduit of the invention has a resistant element connecting two points of the conduit but it does not experience expansion in such a way that it causes thermal fatigue because this resistant element has a through hole through which the coolant liquid passes, putting any of the points thereof at a temperature close to the temperature of the coolant liquid even in the central areas according to the direction in which the resistant element connecting the two different points of the conduit extends.
This resistant element also allows the conduit to withstand higher internal pressures especially when the conduit uses configurations with a flattened transverse section and when the resistant elements connect points between flattened walls located in opposition.

The one or more structural elements are positioned such that they modify the inner section of the conduit without completely closing the conduit.

When the conduit is installed in the heat exchanger, it continues to perform its function as a heat transfer element for transferring heat from the first fluid to the second fluid since the structural elements do not prevent the passage of the first fluid therethrough even though they can modify the inner section.

the one or more structural elements are positioned such that they allow heat exchange between the first fluid intended for circulating inside the conduit and the second fluid intended for circulating inside the through hole of the structural element.

Likewise, the resistant elements must be positioned such that the main function of the conduit is not hindered. Various ways for positioning the structural elements which even allow coexistence with heat exchange elements such as fins, like those used in the state of the art but without causing thermal fatigue especially in the embedment, are considered in the embodiments of the invention.
Another object of the invention is the heat exchanger of an EGR system which uses these conduits therein, as well as the vehicle incorporating an EGR system which in turn has said exchanger.

Description of the Drawings

These and other features and advantages of the invention will be more clearly seen from the following detailed description of a preferred embodiment given only by way of illustrative and non-limiting example in reference to the attached drawings.
Figure 1 shows the inside of a floating core heat exchanger designed for an EGR system which uses an inner conduit configuration among those configurations known in the state of the art. The inside of the heat exchanger is observed since the outer shell has been removed.
This same figure shows an enlarged detail of the embedment of the end of a conduit which has been partially sectioned to observe the inside thereof.
In all cases, the embodiment shown in the figures shows a floating core configuration; nevertheless, heat exchangers formed from the conduits of the invention are not limited to this configuration, also being able to be a monoblock configuration.
Figure 2 shows a heat exchanger containing conduits according to an embodiment of the invention. A line is indicated in this figure corresponding to a plane of section A-A' depicted in the following figure.
This same figure shows a detail of the section of one of the conduits according to a transverse plane P.

Figure 3 shows the conduit sectioned according to plane A-A' indicated in the preceding figure where the arrangement and configuration both of the structural elements with a through hole and of a part with fins extending longitudinally according to a sinusoidal configuration to increase heat transfer can be observed in this section.
Figure 4 shows the same example as in Figures 2 and 3 where the inside of the exchanger is shown in perspective view and with a partial section to show the inside of two of the conduits as well as of the space between said conduits.
Figure 5 shows the same embodiment in a perspective view and with a different viewing angle, without applying a partial section of the conduits thereof.
Figure 6 shows three conduits according to one embodiment, two conduits comprising resistant elements in one region of the conduit and cooling fins in another region of the conduit are shown in the rear part of the figure. A conduit with the same configuration but in exploded perspective view to show its components is shown in the front part of the same figure.
Figure 7 shows an embodiment configuring the resistant elements with a through hole by means of stamping and subsequent welding processes.
Figure 8 shows a heat exchanger comprising conduits according to an embodiment with resistant elements with a through hole distributed such that they define a coolant liquid flow therethrough which is forced to follow a zigzag path.
Figure 9 shows another example of a heat exchanger comprising conduits according to an embodiment with resistant elements with a through hole distributed such that they define a coolant liquid flow therethrough which is forced to follow a path mainly transverse to the path of the gas to be cooled.

Detailed Description of the Invention

Figure 1 shows the inside of a heat exchanger designed for an EGR system incorporating a configuration known in the state of the art. The inside can be observed because the outer shell housing the coolant liquid intended for externally covering a group of conduits (1) is not shown. These conduits (1) form a bundle, a term which could be used to refer to the group of conduits arranged inside the heat exchanger which show one and the same orientation and which are spaced from one another. Particularly, the conduits (1) shown in Figure 1 are oriented according to the direction X-X' which in turn defines a longitudinal direction.
Each of the conduits (1) is fixed at its ends by means of a transverse resistant element, in this particular case a first baffle (2) and a second baffle (3). The first baffle (2) depicted in the figure to the left is the one corresponding to the end of the conduits (1) through which the hot gas enters, and the second baffle (3) arranged at the opposite end is the one corresponding to the exit of the gases once cooled. This second baffle (3) has a perimetral gasket along its perimeter serving for the leak-tight closure with the shell which is not shown because it has been removed to observe the inside of the heat exchanger. This particular configuration corresponds to a floating core exchanger. Nevertheless, the invention is not limited to such exchangers and it is possible to use monoblock exchangers.
The same Figure 1 shows a sectioned detail of one of the conduits (1), the one located in the upper part of the figure according to the orientation chosen for the graphical depiction. The main drawing shows a partial sectioning and the sectioning of the detail shows the parts corresponding to the sections of the material with crosshatching.
Particularly, the first baffle (2) with a perforation (2.1) through which the end (1.1) of the conduit (1) passes is observed, said end (1.1) being housed and embedded therein. The forces exerted by the first baffle (2) on the outer perimeter of the conduit (1) in the event of an expansion of the conduit (1) since the perforation (2.1) where the conduit is housed opposes said expansion are indicated by means of two arrows arranged on the side of the first baffle (2).
A deflector (4) existing in this embodiment which internally increases the exchange surface area is observed in the detail of the conduit in the area to the right. This deflector (4) extends from an area close to the embedment of the end (1.1) of the conduit (1) to an area close to the opposite end of the same conduit (1).
In an operating mode, this deflector (4) is subjected to significant temperature gradients since the upper and lower supports are directly contacting the wall of the conduit (1) which is externally covered by the coolant liquid, and it is internally contacting the gas which just entered the conduit and is at a very high temperature. This high temperature especially in the central area gives rise to expansions exerting a force against the inner wall of the conduit (1) such as those shown with two arrows that are shown with a tendency to be separated from one another.
The two groups of opposing forces, the expansion force due to the temperature of the deflector (4) and the embedment force, give rise to significant stresses favoring conduit fatigue and breakage in this area.
To solve this problem the invention incorporates structural elements (5) with a through hole.
Figure 2 shows a first embodiment of the invention where the structural elements (5) are placed in the area close to the embedment of the first baffle (2). The inner deflector (4), not shown in this figure, does not reach the proximities of the first baffle (2) to make space for the structural elements (5).
This is not the only possible distribution of the structural elements (5) in the conduit (1). Another embodiment also has deflectors in the region where the structural elements (5) are located. A possible method of manufacture consists of configuring the deflector elements (4) by means of a bent plate forming fins and passing the perforations which allow the passage of each structural element (5) through both the walls of the conduit (1) and the plate, giving rise to the inner deflector (4).
The view of Figure 2 also shows a transverse plane P and the section (S) of one of the conduits (1) according to plane P. This section is essentially planar. In this embodiment, the structural elements (5) with a through hole are tube segments connecting two different points of the conduit (1), in this particular case a point of the lower wall and another point of the upper wall. Given that each of the structural elements (5) has a through hole, it is possible for the coolant liquid flow to cross the conduits (1) transversely.
The first problem solved by the structural elements (5) when they are located close to the baffle (2) is the absence of significant stresses in the embedment of the conduit (1) in said first baffle (2) without forgoing heat exchange at the inlet of the conduit (1) or the structural reinforcement as a result. The structural element (5) is a structural reinforcement that does not experience significant expansions since coolant liquid passes therethrough (5) such that even the mid-plane area of the conduit is cooled.
A second problem solved by the presence of the structural elements (5) with a through hole is that it prevents bubble accumulation, which bubbles can be produced at hot points when conduits (1) are arranged horizontally as shown. Even though conduits (1) with an essentially elongated section (S) tend to be oriented vertically to prevent bubble accumulation when bubbles are produced, this is not always possible. In these cases, the conduit (1) of the invention allows the passage therethrough due to the through hole of the structural elements (5).
According to several embodiments, the conduit (1) has a substantially elongated section, for example oval- or rectangular-shaped, and particularly, the conduit has a plate shape limited between two laterally limited wall portions. In these embodiments, the structural elements (5) connecting both wall portions, preferably between points in opposition, are of special interest. In this case, the invention can be carried out using a distribution of the structural elements (5) distributed longitudinally along the direction X-X' (distribution different from that shown in Figure 2), the section (S) being flattened as that shown in Figure 2 for example. If the pressure in the conduit is high, a conduit (1) with the flattened section (S) experiences deformations in the form of expansion mainly on the planar faces. The use of structural elements (5) distributed along the length of the conduit (1) prevents this expansion and allows the conduit (1) to accept greater internal pressures. This solution of distributing the structural elements (5) along the entire length increases the degree of turbulence and can be used without deflectors (4). Nevertheless, it is also possible to have inner deflectors (4).
In the embodiment shown in Figure 2, the structural elements (5) have coinciding through holes such that the passage of coolant liquid flow through the entire bundle of conduits (1) is possible. Any bubble formed on the outer surface of a conduit has an escape route through the holes of the structural elements (5).
This same Figure 2 indicates the plane of section A-A' which allows defining the section shown in Figure 3. Figure 3 shows the inside of the sectioned conduit (1) where it is possible to observe the distribution of the structural elements (5) at the beginning of the end (1.1) where the inlet of the hot gas is located.
According to different embodiments, the structural elements (5) are distributed according to the longitudinal direction (X-X'), distributed substantially in one or more planes (P₁, P₂, P₃) perpendicular to the longitudinal direction (X-X'), or in both. Figure 3 shows a preferred distribution where the distribution is in a staggered manner.
According to other embodiments, the conduit (1) contains an area free of structural elements (5) with a through hole. In the example shown in Figure 3, it is observed that the structural elements (5) are located close to the inlet whereas the rest of the conduit has a deflector (4) covering the rest of the conduit (1).
In this embodiment, the structural element or each of the structural elements (5) are positioned exclusively in an area close to the inlet of the conduit (1) to prevent thermal fatigue at this hot end, preferably in the first or second half of the conduit, or in the first segment of the inlet corresponding to 40%, or to 30%, or to 20%, or to 15%, or to 10% or to 5% of the length of the conduit (5).
According to other embodiments, this distribution of structural elements (5) could also be arranged at the outlet of the conduit (1) for example to facilitate the passage of bubbles at this end.
According to an already described example, the structural elements (5) are distributed along the entire length. In this case, two options are possible, either the deflectors (4) are absent or they are incorporated to improve heat transfer.
In the segment free of structural elements (5) with a through hole, the conduit (1) can have one or more deflectors (4) for the first fluid, for example fins or projections, preferably connected to the wall of the conduit (1) or to integral parts of said wall. The example of Figure 3 shows a deflector (4) formed by a bent aluminum sheet forming longitudinally oriented fins, which sheet is in turn shown as corrugated according to this same longitudinal direction.
The deflector (4) shown in Figure 3 is manufactured by folding sheet metal in a single part which is fixed inside the conduit (1) by means of drawing a plurality of points (1.2) partially penetrating the inside of the conduit (1) for fixing the deflector (4).
Figure 4 shows a perspective view of the inside of an exchanger comprising three conduits (1) according to embodiments of the invention. The partial section of the two conduits (1) located in the upper planes allows observing the staggered arrangement of the structural elements (5) with a through hole at the inlet of the conduits and the presence of the deflector (4) extending to the proximities of the outlet of the conduit (1) spaced slightly from these structural elements (5).
Possible second fluid flow lines having a preferred passage between coinciding through holes and also from or towards the space defined between consecutively located conduits (1) are shown by means of dotted lines with arrows.
This same perspective shows in the section of the first baffle (2) a dotted arrow with the direction of the embedment force. In this example, given that the structural elements (5) are cooled, this embedment force is minimized because the cooled structural elements (5) will expand much less than an inner element such as a deflector (4) without direct cooling.
The attachment between the structural elements (5) and the conduit (1) assures the leak-tightness such that there is no communication between the first fluid and the second fluid. Examples of attachments are crimping, snap-fitting, gluing or by means of welding.
In the embodiments shown in the figures, the structural elements (5) are connected with the walls of the conduit (1) at the level of the inlets and/or outlet thereof such that one or both ends of the structural elements (5) protrude by a specific length to establish the inlet or outlet of the through hole in an area away from the outer surface of the conduit (1) to be cooled. This spacing reduces the temperature of the liquid passing through the through hole, improving the cooling inside the hole. Distances suitable for this spacing can be of the order of the thermal boundary layer located on the surface of the conduit (1). In some embodiments, this distance is between 1/10 and 1/3 of the diameter characteristic of the through hole.
According to other embodiments, the connection between the structural elements (5) and the walls of the conduit (1) is flush for example to facilitate the passage of bubbles through the conduits (1). Another reason for using flush configurations is that the methods of manufacture based on braze welding require a prior expansion step of the resistant element in the perimetral area which is contacting the perforation (1.3) of the conduit (1) and this step is carried out more efficiently with this configuration.
According to other embodiments, one or more structural elements (5) have a bevel at the inlet and/or outlet thereof, preferably integral with the wall of the conduit (1) or after the outer surface of the wall of the conduit (1).
Figure 5 shows a perspective view of the inside of the same exchanger in a different position for observing the outlet (1.1) of the conduits (1) through the second baffle (3). Figure 6 shows an exploded view where the structural elements (5) formed from tubes with a circular section which are inserted in perforations (1.3) of the conduit (1) are observed.
This same Figure 6 shows a sectioned view of the partially inserted deflector (4) in order to observe its square wave-shaped structure with a corrugated configuration according to the longitudinal direction.
Figure 7 shows another method of obtaining resistant elements (5) by means of sheet metal stamping techniques. The conduit is configured for example by means of two half portions which are attached along the side edges. Each of these two half portions is a sheet metal bent at its side edges to give rise to the side closure of the conduit (1) by means of welding, crimping or any method of attachment which generates a leak-tight attachment. Deformation is carried out in each place where a structural element (5) is to be incorporated by drawing a region in a tubular shape. It is possible to generate the perforation located in the center of the deformed region in this same stamping or drawing operation. The result is a wall, for example a slightly oblique converging wall, with a perforation at the bottom. In the opposite half portion in Figure 7, this same repeated deformed region is shown. Since they coincide with one another, the welding of the edges of the coinciding perforations establishes a tubular segment in the form of a through hole connecting both sides of the conduit (1).
Another alternative method of obtaining the structural element (5) combines a half portion such as that shown in Figure 7 and a perforation in the sheet metal of the other half portion. In this case, the welding of the perforation of the deformed region is carried out between the edge of said perforation of the deformed region and the edge of a coinciding perforation in the second half portion.
These conduits (1), which allow the passage therethrough by means of the through holes of the structural elements (5), can also define second fluid flow paths. The passage of the second fluid is not only justified for cooling the structural elements (5) or for allowing the passage of bubbles, but they also allow defining the configuration of the main second fluid flow.
Figure 8 shows an embodiment of a heat exchanger where, from the inlet (6.2) of the second fluid to the outlet (6.1) of the second fluid, there is a plurality of conduits (1) forming a battery or bundle which in turn define spaces between the conduits (1).
The complete or partial side closure of the spaces existing between conduits (1) forces the flow to pass mainly through the through holes of the structural elements (5). In the embodiment shown, the position of groups of structural elements (5) has been alternated at alternating end portions. The alternation requires the flow to change the circulation direction as indicated by means of arrows with dotted lines following a zigzag path in order to pass from one space between the conduits (1) to another.
A particular way of closing the group of conduits (1) laterally, preferably when the conduits have an elongated section, is by having a pair of plates with a leak-tight attachment with each of the side ends of the elongated section of the conduits (1). This attachment is preferably carried out using a configuration of the sides of the conduits with a straight segment to favor the attachment. Therefore, it is possible to prevent the use of an outer shell, and the passage of the second fluid is limited to the space between conduits (1).
According to this configuration, the conduits (1) are distributed according to a stack, and the conduits arranged at the ends can act as a closure if they do not incorporate structural elements (5) with a through hole. Therefore, also according to another embodiment, at least one face or part of a face of the conduit or conduits (1) forms part of the outer wall of the shell (6).
Concerning the section of the structural elements (5), said section can be round, square, elongated, rectangular or oval, among others, and if there is more than one conduit, these conduits can combine different sections.
Figure 9 shows another embodiment in which the structural elements (5) define a transverse second fluid flow with respect to the path of the first fluid. In this embodiment, the inlet (6.2) of the second fluid has a small chamber for distributing the flow passing transversely through each conduit (1) through a plurality of structural elements (5) with a through hole distributed along the length of the conduit (1). An outlet manifold collects the flow heading towards the outlet (6.1).
In this embodiment, if the conduits (1) with an elongated section are in a horizontal position, a bubble formed in the exchanger due to having reached the vapor phase at one point can move up through any of the through holes of the structural elements (5), preventing it from being retained. According to the orientation shown in this Figure 9, the first fluid passes horizontally from left to right, and the second fluid passes vertically from bottom to top as shown by the arrows with a dotted line.

Claims

A conduit (1) for a heat exchanger of an internal combustion engine EGR system, the heat exchanger allowing heat exchange between a first fluid, preferably an EGR gas to be cooled, intended for circulating inside the conduit (1), and a second fluid, preferably a coolant liquid, intended for circulating on the outside of said conduit (2) without the two fluids contacting one another,
where the conduit (1) extends substantially according to a longitudinal direction (X-X') between an inlet and an outlet and has an inner section (S), extending in a plane (P) perpendicular to the longitudinal direction (X-X');
characterized in that
- the conduit (1) formed, among others, by a limiting wall between the inside and the outside thereof is traversed by one or more extending structural elements (5) connecting two different points of the limiting wall of the conduit (1) where these structural elements (5) have a through hole such that they allow the passage of the second fluid through said structural element (5) for its cooling,

- the one or more structural elements (5) are positioned such that they modify the inner section (S) of the conduit without completely closing the conduit (1); and,

- the one or more structural elements (5) are positioned such that they allow heat exchange between the first fluid intended for circulating inside the conduit (1) and the second fluid intended for circulating inside the through hole of the structural element.
The conduit (1) according to claim 1, characterized in that the different points of the limiting wall of the conduit connecting the structural element are points arranged in opposition according to the inner section (S) of the conduit (1).
The conduit (1) according to claim 1 or 2, characterized in that it contains a plurality of structural elements (5) distributed according to the longitudinal direction (X-X'), substantially distributed in one or more planes (P) perpendicular to the longitudinal direction (X-X'), or in both, where the structural elements (5) are preferably positioned in a staggered manner to cause turbulence in the first fluid.
The conduit (1) according to any of the preceding claims, characterized in that it contains an area free of structural elements (5) with a through hole, the structural element or each of the structural elements being positioned exclusively in an area close to the inlet or to the outlet of the conduit (1), preferably in the first or second half portion of the conduit, or in the first segment of the outlet or of the inlet corresponding to 40%, or to 30%, or to 20%, or to 15%, or to 10% or to 5% of the length of the conduit (5).
The conduit (1) according to any of the preceding claims, characterized in that it contains one or more deflectors (4) for the first fluid, different from the structural element or elements (5), for example fins, projections, preferably connected to the wall of the conduit (1) or to integral parts of said wall, the deflector or deflectors (4) preferably being located in an area of the conduit (1) free of structural elements (5) with a through hole.
The conduit (1) according to any of claims 1 to 5, characterized in that it contains one or more deflectors (4) for the first fluid, different from the structural element or elements (5), for example fins, projections, preferably connected to the wall of the conduit (1) or to integral parts of said wall, the deflector or deflectors (4) being in an area where there are structural elements (5).
The conduit (1) according to any of the preceding claims, characterized in that the section of the conduit (1) is substantially elongated, for example oval- or rectangular-shaped, and particularly, the conduit has a plate shape limited between two essentially planar wall portions in opposition and connected by two side edges according to the longitudinal direction, where the structural element or elements (5) with a hole connect both wall portions.
The conduit (1) according to claim 7, characterized in that the structural elements (5) are distributed along the length of the conduit (1) to prevent the deformation of said conduit (1) by expansion.
The conduit (1) according to any of the preceding claims, characterized in that one or more structural elements (5) are connected to the walls of the conduit (1) by means of an attachment, preferably an integral attachment, such as for example by means of welding, by means of crimping, by snap-fitting, by gluing or in an integral manner with the wall of the conduit (1).
The conduit (1) according to any of claims 1 to 8, characterized in that the structural elements (5) are obtained by stamping or drawing sheet metal with a perforation of the bottom of the drawn region, preferably by means of two half portions, where the drawing is either:
- in both half portions with the subsequent attachment of the edges of the perforations of the drawings

- or the drawing is in one half portion and in the other half portion there is only a perforation;
where in either case the half portions are attached to one another to form the conduit (1).
The conduit according to any of the preceding claims, characterized in that one or more structural elements (5) are connected with the walls of the conduit (1) at the level of the inlets and/or outlets thereof such that one or both ends of the structural elements (5) are either flush with the outer surface of the conduit (1) or protrude by a specific length to establish the inlet or outlet of the through hole in an area away from the outer surface of the conduit (1) to be cooled.
A heat exchanger for an internal combustion engine EGR system characterized in that it comprises a conduit (1) according to any of the preceding claims or a battery formed by a bundle of conduits (1) according to any of the preceding claims, where the conduits (1) preferably extend in a manner substantially parallel to one another according to the longitudinal direction (X-X').
The heat exchanger according to claim 9, characterized in that it contains a shell (6) housing the battery of conduits (1), the inside of the conduits (1) collectively forming the passage for the first fluid, preferably the gas to be cooled, between an inlet of the exchanger for the first fluid and an outlet of the exchanger for the first fluid; and where the spaces between the shell and the battery of conduits (1), the spaces arranged between the conduits (1) themselves, and the through holes of the structural elements (5) collectively form the passage for the second fluid, preferably the coolant liquid, between an inlet (6.2) of the exchanger for the second fluid and an outlet (6.1) of the exchanger for the second fluid.
The heat exchanger according to claim 12 or 13, characterized in that the battery of conduits (1) is positioned such that for the second fluid to go from the inlet (6.2) of the exchanger to the outlet (6.1) of the exchanger when in use, it is forced to pass through at least one through hole of a structural element of one or more conduits (1), preferably all of them, forming the battery.
The heat exchanger according to any of claims 12 to 14, characterized in that the conduits (1) contact or are connected to, by one or both edges, the inner surface of the shell (6), preferably in a leak-tight manner, to prevent the passage of the second fluid between the conduit (1) and the shell (6), forcing the passage of the flow through the at least one.
The heat exchanger according to any of claims 12 to 15, characterized in that the battery is formed by an alternation of conduits (1) with an area free of structural elements (5) with a through hole close to the inlet of the first fluid and of conduits (1) with an area free of structural elements (5) with a through hole close to the outlet of the first fluid so that the passage for the second fluid has a zigzag shape in the passage thereof through consecutive conduits (1).
The heat exchanger according to any of claims 12 to 15, characterized in that the battery is formed with at least a stack of conduits (1) with a plurality of structural elements (5) with a through hole distributed along the length of each conduit (1) to establish a second fluid flow essentially transverse to the path of the first fluid flow.
An EGR system for an internal combustion engine characterized in that it comprises an exchanger according to any of claims 12-17.
A vehicle comprising a heat exchanger according to any of claims 12 to 17 or comprising an EGR system according to claim 18.