Exhaust gas recirculation cooler

Abstract

The utility model relates to an exhaust gas recirculation cooler (8) for a motor vehicle (1), in particular for a passenger vehicle, which is provided with a heat transfer tube bundle assembly (27) through which exhaust gas (48) to be cooled can be guided, the heat transfer tube bundle assembly (27) is provided with a plurality of heat transfer tubes (34), and the heat transfer tubes (34) respectively surround inner tube spaces (39). Swirlers (45) for swirling exhaust gas (48) that can be conducted through the heat transfer tube bundle assembly (27) are molded onto the heat transfer tubes (34), which swirlers (45) project into the tube interior (39), which swirlers (45) each have an elongated geometry, and which swirlers (45) surround only partially around the heat transfer tubes (34) as viewed in the respective circumferential direction (44) of the heat transfer tubes (34).

Description

Technical Field

[0001] The utility model relates to an exhaust gas recirculation cooler for a motor vehicle, in particular for a passenger car. Background Art

[0002] In an internal combustion engine, the exhaust gas of the internal combustion engine can be guided back into the combustion cycle of the internal combustion engine from the exhaust system to reduce the emission of nitrogen oxides. To improve the efficiency of such exhaust gas recirculation, it is advantageous to cool the recirculated exhaust gas before it is supplied to the internal combustion engine. For this purpose, a so-called exhaust gas recirculation cooler can be used. The goal of such an exhaust gas recirculation cooler is to extract as much heat as possible from the exhaust gas.

[0003] The exhaust gas flow cooled by the exhaust gas recirculation cooler carries soot particles. If the exhaust gas recirculation cooler is used for a long time (usually over the entire service life of the vehicle), the soot particles are deposited in the heat transfer tubes of the exhaust gas recirculation cooler, and the cross-section of the heat transfer tubes is reduced. This change in cross-section in turn leads to a change in the flow velocity inside the heat transfer tubes, and thus affects the achieved cooling rate. In extreme cases, the deposition of soot particles can cause the heat transfer tubes to become blocked, at which point it becomes necessary to replace the entire exhaust gas recirculation cooler. Summary of the Utility Model

[0004] In this context, the object of the utility model is to provide an improved exhaust gas recirculation cooler.

[0005] Therefore, an exhaust gas recirculation cooler for a motor vehicle, in particular for a passenger car, is proposed. The exhaust gas recirculation cooler includes a heat transfer tube bundle assembly through which the exhaust gas to be cooled can be guided. The heat transfer tube bundle assembly has a plurality of heat transfer tubes, each of which surrounds a tube inner space. A vortex generator for agitating the exhaust gas that can be guided through the heat transfer tube bundle assembly is molded onto the heat transfer tube. The vortex generator extends into the tube inner space. The vortex generators each have an elongated geometry, and when observed along the respective circumferences of the heat transfer tubes, the vortex generators only partially surround the heat transfer tubes.

[0006] Due to the provision of the vortex generators, the exhaust gas flowing through the heat transfer tube bundle assembly generates vortices. On the one hand, this prevents the deposition of carbon black particles in the tube inner space, and on the other hand, it improves the heat transfer from the exhaust gas to the cooling medium flowing through the exhaust gas recirculation cooler. Thus, the vortex generators affect both the exhaust gas flowing through the tube inner space and the coolant flowing around the heat transfer tubes. In addition, since the vortex generators only partially surround the heat transfer tubes, the heat transfer tubes can be simply manufactured, for example, by deep drawing.

[0007] The exhaust gas recirculation cooler is preferably part of the exhaust system of an automotive internal combustion engine. An exhaust gas recirculation valve can be installed on the exhaust gas recirculation cooler, by means of which the exhaust gas recirculation cooler can be switched from a bypass mode or a by-pass mode to a cooling mode and vice versa. In the cooling mode, the exhaust gas is guided through the heat transfer tube bundle assembly, and the exhaust gas is cooled at this time. In the bypass mode, a bypass line guides the exhaust gas past the heat transfer tube bundle assembly. In this case, compared with the cooling mode, little or no heat is extracted from the exhaust gas.

[0008] The exhaust gas recirculation cooler preferably includes a tubular housing, which is closed at the end sides by a first cover plate and a second cover plate. The heat transfer tube bundle assembly is arranged between the first cover plate and the second cover plate. The heat transfer tube bundle assembly can be connected to the first cover plate and to the second cover plate. The above-mentioned cooling medium, in particular water, is guided through the housing in order to extract heat from the exhaust gas flowing through the heat transfer tube bundle assembly.

[0009] The heat transfer tube bundle assembly preferably has a serpentine geometry. Thereby, the path that the exhaust gas must travel through the exhaust gas recirculation cooler is increased, so that the residence time of the exhaust gas in the exhaust gas recirculation cooler is prolonged. Compared with the case where the exhaust gas is guided through the exhaust gas recirculation cooler on a direct path, for example through a bypass line, this makes it possible to extract more heat from the exhaust gas.

[0010] The first cover plate preferably has a plurality of first exhaust gas inlets, which are in fluid connection with the heat transfer tubes of the heat transfer tube bundle assembly. The second cover plate preferably has an exhaust gas collector, which is also in fluid connection with the heat transfer tubes. The first exhaust gas inlets are preferably arranged below the exhaust gas collector. Thereby, the exhaust gas recirculation cooler can have a more compact structure. The bypass line preferably extends directly from the first cover plate to the second cover plate, so that the exhaust gas travels through the exhaust gas recirculation cooler on as short a path as possible in the bypass mode.

[0011] The number of heat transfer tubes is arbitrary. For example, the heat transfer tubes can be arranged in a matrix or a pattern. In the present case, "matrix" or "pattern" in particular means that the heat transfer tubes are arranged side by side or stacked in rows or columns. For example, there are six columns with five rows of heat transfer tubes each. In the cooling mode, the exhaust gas flows through the inner space of the heat transfer tubes. The heat transfer tubes separate their respective inner spaces from the outer spaces. The cooling medium flows through the outer spaces. The outer spaces are surrounded by the housing and the cover plates of the exhaust gas recirculation cooler.

[0012] In a top view, the swirl generator in particular has an elongated, in particular rectangular, geometry. In the present case, an "elongated" or "extended" geometry should in particular refer to a geometry that includes a main extension direction, i.e., along this direction the geometry has its maximum geometric extension dimension. For example, such an elongated geometry can be rectangular, trapezoidal, triangular, oval or elliptical or similar shapes. However, in the present case, an "elongated geometry" preferably should not refer to a geometry that completely surrounds the respective circumferential direction of the heat transfer tube.

[0013] In the present context, a "swirl generator" in principle refers to a component or section of a heat transfer tube that is adapted to deflect a fluid, in the present case exhaust gas, and in particular to generate a swirl at this time. The swirl generator projects into the interior space of the tube such that the swirl generator can cause the exhaust gas flowing through the interior space of the tube to swirl. Here, the swirl generator narrows the flow cross-section of the interior space of the tube, and in the cooling mode, the exhaust gas flows through the flow cross-section.

[0014] In the present context, the "circumferential direction" should be understood as a direction oriented perpendicular to the longitudinal direction of the respective heat transfer tube. The longitudinal direction can be oriented from the first cover plate towards the second cover plate or vice versa. The longitudinal direction can be consistent with the flow direction of the exhaust gas flowing through the respective heat transfer tube in the cooling mode. However, this is not a mandatory requirement. The longitudinal direction preferably is consistent with the main extension direction of the respective heat transfer tube. In the present context, the "main extension direction" should refer to the direction in which the respective heat transfer tube has its maximum geometric extension dimension.

[0015] The circumferential direction can surround the respective heat transfer tube in a clockwise or counterclockwise direction. Thus, "circumferential / circumferentially" means along the circumferential direction. Thus, the heat transfer tube is circumferentially closed. The circumferential direction can surround the heat transfer tube along the outer surface of the respective heat transfer tube. The swirl generator in particular is only molded on a partial area of the heat transfer tube. In the present context, a "partial area" should mean that the swirl generator does not completely surround the heat transfer tube, but only partially surrounds the heat transfer tube. This can for example mean that the swirl generator is only provided on the bottom and on the top cover, but not on the side wall of the heat transfer tube.

[0016] One advantage of this arrangement of the swirl generator is that the flow velocity is lower on the side wall and higher along the bottom and the top cover. As a result, a stronger swirl also occurs.

[0017] "The swirl generator is only molded on a partial area of the heat transfer tube" in particular means that the swirl generator preferably does not completely surround the heat transfer tube in a spiral or ribbed manner. Each heat transfer tube can have any number of swirl generators. When viewed in the longitudinal direction of the heat transfer tube, the swirl generators in particular are spaced apart from each other and arranged parallel to each other. However, this is not a mandatory requirement.

[0018] According to one embodiment, the turbulator is configured to be molded onto a recess on the heat transfer tube on the outside.

[0019] The turbulator can in particular be molded onto the heat transfer tube by means of a deep drawing process. This enables the economical production of the heat transfer tube and thus also the economical production of the exhaust gas recirculation cooler.

[0020] According to another embodiment, the turbulator is arranged obliquely to the longitudinal direction of the heat transfer tube.

[0021] The longitudinal direction is in particular oriented from the first cover plate towards the second cover plate or vice versa. All heat transfer tubes in the heat transfer tube bundle assembly extend in the longitudinal direction. Thus, all heat transfer tubes preferably extend parallel to each other. The turbulator is inclined to the longitudinal direction at a certain inclination angle respectively. The inclination angle is for example 40° to 80°, preferably 50° to 70°, more preferably 60°. However, any other inclination angle can also be selected. All turbulators can have the same inclination angle. However, these turbulators can also have different inclination angles.

[0022] According to another embodiment, the turbulator has a rectangular geometry, and the edges of the rectangular geometry are preferably rounded.

[0023] In a plan view or a top view, the turbulator in particular has a rectangular geometry. However, as described above, the turbulator can also be oval, trapezoidal or triangular, or have any other elongated or stretched geometry.

[0024] According to another embodiment, a projection is molded onto the heat transfer tube, and the projection extends away from the inner space of the tube, so that the projection forms a cavity in fluid connection with the inner space of the tube, and the projection is preferably frustoconical.

[0025] The projection preferably extends outward into the aforementioned outer space of the tube. These projections improve the heat transfer from the exhaust gas to the cooling medium. In addition, it can also have a positive effect on the exhaust gas flow in the inner space of the tube. In addition, the projection can also serve as a storage part for the carbon black deposits that occur. In addition, the heat transfer tube can be strengthened by means of the projection.

[0026] According to another embodiment, adjacent heat transfer tubes abut against each other with their projections.

[0027] This ensures that the heat transfer tubes are spaced apart from each other, so that the cooling medium can flow through between the heat transfer tubes. The heat exchange between the heat transfer tubes is additionally improved by the abutment of the heat transfer tubes on the projections.

[0028] According to another embodiment, the heat transfer tube is a flat tube, so that the heat transfer tube has a bottom, a top cover, a first side wall connecting the bottom and the top cover, and a second side wall connecting the bottom and the top cover respectively, and the swirl generator is only molded onto the bottom and / or onto the top cover.

[0029] The heat transfer tube especially has a rectangular geometry in cross-section. The rectangular geometry preferably has rounded edges. The bottom and the top cover extend parallel to each other and are spaced apart from each other. The first side wall and the second side wall are preferably rounded and can respectively have a C-shaped geometry in cross-section. These two side walls preferably do not have swirl generators. In other words, the side walls are without swirl generators or are swirl-generator-free. The aforementioned protrusions are preferably also only molded onto the bottom and / or onto the top cover. In the case where the swirl generators are molded onto both the bottom and the top cover, the swirl generators preferably tilt in the opposite or relative direction, so as to obtain a cross-shaped arrangement of the swirl generators. At this time, the swirl generators on the bottom and the swirl generators on the top cover preferably tilt equally with respect to the longitudinal direction, but especially have tilt angles with different plus and minus signs. In other words, the swirl generators on the bottom and the swirl generators on the top cover are preferably arranged crosswise or intersectingly.

[0030] According to another embodiment, the exhaust gas recirculation cooler has a plurality of heat transfer tube bundles and a plurality of turning caps, and the turning caps fluidly connect the heat transfer tube bundles to each other, and the heat transfer tube bundles extend parallel to each other.

[0031] Preferably, a first heat transfer tube bundle, a second heat transfer tube bundle, and a third heat transfer tube bundle are provided. These heat transfer tube bundles are preferably arranged one above the other, and at this time, the second heat transfer tube bundle is arranged between the first heat transfer tube bundle and the third heat transfer tube bundle. Each heat transfer tube bundle has a plurality of heat transfer tubes. For example, each heat transfer tube bundle can have thirty heat transfer tubes. The number of heat transfer tubes in each heat transfer tube bundle is preferably the same. The heat transfer tubes are arranged such that the above-described serpentine structure of the heat transfer tube bundle assembly is obtained.

[0032] According to another embodiment, the exhaust gas recirculation cooler has exactly three heat transfer tube bundles and exactly two turning caps, and at this time, exactly one turning cap respectively fluidly connects exactly two heat transfer tube bundles to each other.

[0033] Preferably, a first turning cap and a second turning cap are provided. The first turning cap fluidly connects the first heat transfer tube bundle and the second heat transfer tube bundle. The second turning cap fluidly connects the second heat transfer tube bundle and the third heat transfer tube bundle. The first heat transfer tube bundle is preferably fluidly connected to the first exhaust gas inlet described in front of the first cover plate. The third heat transfer tube bundle is preferably fluidly connected to the exhaust gas collector described in front of the second cover plate. All the heat transfer tubes of the first heat transfer tube bundle lead into the first turning cap, and the first turning cap distributes the exhaust gas to all the heat transfer tubes of the second heat transfer tube bundle at this time. All the heat transfer tubes of the second heat transfer tube bundle lead into the second turning cap, and the second turning cap distributes the exhaust gas evenly to the heat transfer tubes of the third heat transfer tube bundle at this time.

[0034] According to another embodiment, the heat transfer tube is made of a composite material, which includes a first material with a first thermal conductivity and a second material with a second thermal conductivity. The first thermal conductivity is greater than the second thermal conductivity. The first material is arranged facing away from the inner space of the tube, and the second material is arranged facing the inner space of the tube. The first material is preferably copper or brass, and the second material is preferably stainless steel.

[0035] Using a composite material improves heat transfer. The first material preferably faces the cooling medium, and at this time, the second material faces the exhaust gas. Thus, the first material faces the outer space of the tube, and at this time, the second material faces away from the outer space of the tube. To manufacture the heat transfer tube, the first material in the form of copper or brass can be connected to, for example, a stainless steel plate. In addition, the first material in the form of copper or brass can be applied to the second material in the form of a stainless steel plate in the form of a coating.

[0036] In this context, "a" is not necessarily to be understood as being limited to exactly one element. On the contrary, multiple elements can also be provided, such as two, three, or more elements. Each other counting word used here is not necessarily to be understood as having the following meaning, that is, there is a limitation to exactly the number of elements stated. On the contrary, as long as there is no contrary indication, numerical deviations may exist both upwards and downwards.

[0037] Other possible embodiments of the exhaust gas recirculation cooler also include combinations of features or embodiments not explicitly mentioned in the foregoing or below for the embodiments. Here, a person skilled in the art can also add individual aspects to the corresponding basic form of the exhaust gas recirculation cooler as improvements or supplements. Description of the Drawings

[0038] Other advantageous design solutions and aspects of the exhaust gas recirculation cooler are the subject matter of the dependent claims and the embodiments described below of the exhaust gas recirculation cooler. In addition, the exhaust gas recirculation cooler is described in detail with reference to the accompanying drawings according to a preferred embodiment.

[0039] Figure 1Schematic side view showing an embodiment of a motor vehicle;

[0040] Figure 2 Shows for according to Figure 1 Schematic perspective view of an embodiment of an exhaust gas recirculation cooler for a motor vehicle;

[0041] Figure 3 Shows according to Figure 2 Another schematic perspective view of the exhaust gas recirculation cooler;

[0042] Figure 4 Shows according to Figure 2 Another schematic perspective view of the exhaust gas recirculation cooler;

[0043] Figure 5 Shows for according to Figure 2 Schematic perspective view of a heat transfer tube bundle assembly of an exhaust gas recirculation cooler;

[0044] Figure 6 Shows for according to Figure 5 Schematic top view of an embodiment of a heat transfer tube of a heat transfer tube bundle assembly;

[0045] Figure 7 Shows according to Figure 6 Schematic perspective sectional view of the heat transfer tube;

[0046] Figure 8 Shows according to Figure 6 Another schematic perspective sectional view of the heat transfer tube;

[0047] Figure 9 Shows according to Figure 2 Schematic side view of the exhaust gas recirculation cooler; and

[0048] Figure 10 Shows according to Figure 2 Another schematic side view of the exhaust gas recirculation cooler. Detailed Description

[0049] In the figures, unless otherwise stated, identical or functionally identical elements are provided with the same reference numerals.

[0050] Figure 1 Schematic side view showing an embodiment of a motor vehicle 1. The motor vehicle 1 is in particular a passenger car. The motor vehicle 1 can also be a commercial vehicle, such as a truck, a combine harvester or a construction machine. In addition, the motor vehicle 1 can also be a military vehicle. However, in the following, it is assumed that the motor vehicle 1 is a passenger car.

[0051] The motor vehicle 1 includes a body 2 that encloses the passenger compartment or the interior 3 of the motor vehicle. The driver and passengers can stay in the interior 3 of the motor vehicle. The body 2 separates the surrounding environment 4 of the motor vehicle 1 from the interior 3 of the motor vehicle. The interior 3 of the motor vehicle can be accessed via a door.

[0052] The motor vehicle 1 includes a chassis having a plurality of wheels 5, 6. The number of wheels 5, 6 is in principle arbitrary. The motor vehicle 1 preferably has four wheels 5, 6. However, the motor vehicle 1 can also have six wheels 5, 6. The wheels 5, 6 are part of the chassis of the motor vehicle 1. It is possible that only two wheels 5, 6 are driven. However, it is also possible that all wheels 5, 6 are driven. In this case, the motor vehicle 1 is an all-wheel drive vehicle.

[0053] The motor vehicle 1 includes an internal combustion engine or an internal combustion engine 7. The internal combustion engine 7 can be a gasoline engine. However, the internal combustion engine 7 can also be a diesel engine. The motor vehicle 1 can be driven only by the internal combustion engine 7. However, the motor vehicle 1 can also be a hybrid vehicle. In this case, in addition to the internal combustion engine 7, the motor vehicle 1 also has at least one electric motor.

[0054] Figure 2 A schematic perspective view showing an embodiment of the exhaust gas recirculation cooler 8 for the internal combustion engine 7 is shown. Figure 3 Another schematic perspective view of the exhaust gas recirculation cooler 8 is shown. Figure 4 Another schematic perspective view of the exhaust gas recirculation cooler 8 is shown. Reference is made simultaneously below to Figures 2 to 4 .

[0055] An exhaust system is provided for the internal combustion engine 7. The exhaust gas recirculation cooler 8 can be part of the exhaust system. By means of the exhaust gas recirculation cooler 8, exhaust gas can be extracted from the exhaust system in the form of so-called exhaust gas recirculation, cooled and supplied again to the internal combustion engine 7. In this exhaust gas recirculation, the exhaust gas is returned to the combustion cycle of the internal combustion engine 7. The exhaust gas recirculation is used to reduce nitrogen oxide emissions. If it is a gasoline engine, the exhaust gas recirculation cooler 8 is also used to reduce fuel consumption.

[0056] The exhaust gas recirculation cooler 8 includes a housing 9. The housing 9 can be tubular. The housing 9 has in particular a rectangular geometry in cross-section. The housing 9 includes two side walls 10 that are opposite each other, and only one of these side walls is shown in Figure 2 In addition, the housing 9 also includes a bottom 11 and a top cover 12 that is opposite the bottom 11. The side walls 10, the bottom 11 and / or the top cover 12 can be reinforced by means of hemming 13, and only one of these hemmings is shown in Figure 2Reference numerals are marked. Mounting elements 14, 15 can be provided on the bottom 11 and on the top cover 12, by means of which the exhaust gas recirculation cooler 8 can be mounted on the motor vehicle 1. In addition, an exhaust port 16 is also mounted on the top cover 12. Optionally, there may also be Figure 2 a second exhaust port not shown in the figure, which can be used for exhausting gas or for auxiliary circulation.

[0057] The housing 9 is closed at the end sides by a first cover plate 17 and a second cover plate 18. An exhaust gas recirculation valve (not shown) is mounted on the first cover plate 17. The housing 9 can be brazed or welded to the cover plates 17, 18. The first cover plate 17 includes a plurality of first exhaust gas inlets 19, and among the first exhaust gas inlets, only one first exhaust gas inlet is marked with a reference numeral in Figure 2 and 4 respectively. The first exhaust gas inlets 19 can have a rectangular geometry. In addition, there are a plurality of second exhaust gas inlets 20 on the first cover plate, and among these second exhaust gas inlets, only one second exhaust gas inlet is marked with a reference numeral in Figure 2 and 4 respectively. The second exhaust gas inlets 20 can have a circular geometry. In the Figures 2 to 4 orientation, the second exhaust gas inlets 20 are located above the first exhaust gas inlets 19. In addition, the first cover plate 17 also has two cooling medium inlets 21, 22.

[0058] The second cover plate 18 has an exhaust gas collector 23, which can be configured as a truncated pyramid. The exhaust gas outlet pipe 24 is mounted on the exhaust gas collector 23 by means of a mounting flange 25. In addition, a connecting pipe 26 is also mounted on the exhaust gas collector 23. In the Figures 2 to 4 orientation, the exhaust gas collector 23 is arranged above the first exhaust gas inlets 19.

[0059] A heat transfer tube bundle assembly 27 is arranged inside the housing 9. The task of the heat transfer tube bundle assembly 27 will be described below. The heat transfer tube bundle assembly 27 is fluidly connected to the first exhaust gas inlets 19 and to the exhaust gas collector 23. This especially means that, by means of the heat transfer tube bundle assembly 27, the exhaust gas can be guided from the first exhaust gas inlets 19 of the first cover plate 17 to the exhaust gas collector 23 of the second cover plate 18. At this time, the exhaust gas collector 23 has a serpentine geometry in order to make the path of the exhaust gas from the first exhaust gas inlets 19 to the exhaust gas collector 23 as long as possible.

[0060] In addition, a plurality of bypass pipes or bypass lines 28 are also arranged inside the housing 9. For example, five such bypass lines 28 are provided. The bypass lines 28 are in Figure 3 and 4above the heat transfer tube bundle assembly 27 in the orientation. The bypass line 28 extends between the first cover plate and the second cover plate 18, and at this time the bypass line 28 extends straight. These bypass lines 28 can each have a circular cross-section. The bypass line 28 is fluidly connected to the second exhaust gas inlet 20. In addition, the bypass line 28 is also fluidly connected to the exhaust gas collector 23.

[0061] Figure 5 Shows a schematic perspective view of an embodiment of the heat transfer tube bundle assembly 27 as described above.

[0062] The heat transfer tube bundle assembly 27 has a plurality of heat transfer tube bundles 29, 30, 31. Preferably, exactly three heat transfer tube bundles 29, 30, 31 are provided, and these heat transfer tube bundles are arranged in a stacked manner within the housing 9. In particular, a first heat transfer tube bundle 29, a second heat transfer tube bundle 30, and a third heat transfer tube bundle 31 are provided. At this time, the second heat transfer tube bundle 30 is arranged between the first heat transfer tube bundle 29 and the third heat transfer tube bundle 31.

[0063] The first heat transfer tube bundle 29 is fluidly connected to the first exhaust gas inlet 19 of the first cover plate 17. The third heat transfer tube bundle 31 is fluidly connected to the exhaust gas collector 23 of the second cover plate 18. During the operation of the exhaust gas recirculation cooler 8, the exhaust gas flows into the first heat transfer tube bundle 29 through the first exhaust gas inlet 19, flows through the second heat transfer tube bundle 30 and the third heat transfer tube bundle 31, and then enters the exhaust gas collector 23.

[0064] In addition to the heat transfer tube bundles 29, 30, 31, the heat transfer tube bundle assembly 27 also has a plurality of turning caps 32, 33, and the turning caps fluidly connect the heat transfer tube bundles 29, 30, 31 to each other. Particularly preferably, exactly two such turning caps 32, 33 are provided. The heat transfer tube bundle assembly 27 has a first turning cap 32 and a second turning cap 33. The first turning cap 32 connects the first heat transfer tube bundle 29 to the second heat transfer tube bundle 30. The second turning cap 33 connects the second heat transfer tube bundle 30 to the third heat transfer tube bundle 31.

[0065] Each heat transfer tube bundle 29, 30, 31 includes a plurality of heat transfer tubes 34, and here, in Figure 5 only one heat transfer tube 34 in the first heat transfer tube bundle 29 is labeled with a reference numeral. For example, the heat transfer tube bundles 29, 30, 31 can have thirty such heat transfer tubes 34. However, the number of heat transfer tubes in each heat transfer tube bundle 29, 30, 31 is arbitrary. For each heat transfer tube bundle 29, 30, 31, these heat transfer tubes 34 can be arranged in a matrix or pattern. In the current case, "matrix" or "pattern" should in particular mean that the heat transfer tubes 34 can be arranged in rows and columns. For example, for each heat transfer tube bundle 29, 30, 31, six columns of such heat transfer tubes 34 with five rows each are provided.

[0066] The heat transfer tubes 34 of the first heat transfer tube bundle 29 are fluidly connected to the first exhaust gas inlet 19 of the first cover plate 17. The heat transfer tubes 34 of the third heat transfer tube bundle 31 are fluidly connected to the exhaust gas collector 23 of the second cover plate 18. The second heat transfer tube bundle 30 is fluidly connected to the heat transfer tube bundles 29 and 31 by means of deflection caps 32 and 33. The heat transfer tubes 34 extend in the direction from the first cover plate 17 towards the second cover plate 18 respectively. Here, all the heat transfer tubes 34 of all the heat transfer tube bundles 29, 30, and 31 extend parallel to each other.

[0067] Figure 6 A schematic top view showing an embodiment of the heat transfer tube 34 as described above. Figure 7 A schematic perspective cross-sectional view showing the heat transfer tube 34. Figure 8 A schematic perspective cross-sectional view showing another heat transfer tube 34. At the same time, refer to the following Figures 6 to 8 .

[0068] The heat transfer tube 34 is a flat tube. The heat transfer tube 34 has, in particular, a geometric shape of a rounded rectangle in cross-section. The heat transfer tube 34 has a bottom 35, a top cover 36 disposed opposite to the bottom 35, a first side wall 37, and a second side wall 38 disposed opposite to the first side wall 37. The side walls 37 and 38 are arcuate. The side walls 37 and 38 may have a C-shaped geometry in cross-section. The side walls 37 and 38 connect the bottom 35 to the top cover 36.

[0069] The bottom 35, the top cover 36, and the two side walls 37 and 38 enclose an inner tube space 39 through which the exhaust gas flows. The bottom 35, the top cover 36, and the two side walls 37 and 38 separate the inner tube space 39 from the outer tube space 40. Spacers 41 and 42 may be mounted on the side walls 37 and 38, and the heat transfer tubes 34 may abut against each other at the spacers, and the heat transfer tubes 34 of the heat transfer tube bundles 29, 30, and 31 may be kept spaced apart from each other by means of the spacers.

[0070] The heat transfer tube 34 includes a longitudinal direction 43. The longitudinal direction 43 is oriented in the direction from the first cover plate 17 towards the second cover plate 18 or vice versa. The longitudinal direction 43 may be consistent with the flow direction of the exhaust gas through the heat transfer tube 34. However, this is not a mandatory requirement. The longitudinal direction 43 is consistent with the main extension direction of the heat transfer tube 34. In the present case, the "main extension direction" should be understood as the following direction, in which the heat transfer tube 34 has its maximum geometric extension dimension.

[0071] In addition, the heat transfer tube 34 is also provided with a circumferential direction. The circumferential direction 44 extends along the periphery of the heat transfer tube 34. The circumferential direction 44 is oriented perpendicular to the longitudinal direction 43. The circumferential direction 44 can surround the heat transfer tube 34 in a clockwise or counterclockwise direction. Therefore, "circumferential" means along the circumferential direction 44. Thus, the heat transfer tube 34 is circumferentially closed. The circumferential direction 44 can surround the heat transfer tube along the outer surface of the heat transfer tube 34.

[0072] A plurality of swirlers 45 are molded onto the heat transfer tube 34 to cause the exhaust gas guided through the heat transfer tube bundle assembly 27 to generate swirls. The swirlers 45 are preferably provided only on the bottom 35 and on the top cover 36. The side walls 37, 38 do not have the swirlers 45. This especially means that, when observed along the circumferential direction 44, the swirlers 45 do not completely surround the heat transfer tube 34. Thus, the swirlers 45 are molded only onto a partial area of the heat transfer tube 34. In the present case, the "partial area" should be understood as that the swirlers 45 are molded only onto the bottom 35 and the top cover 36, and not onto the side walls 37, 38. The swirlers 45 can be molded onto the heat transfer tube 34 by means of a deep drawing method.

[0073] In the top view according to Figure 6 , the swirlers 45 have an elongated, especially rectangular, geometry with rounded edges. In the present case, the "elongated" geometry should especially be understood as a geometry that includes a main extension direction, that is, a direction along which the geometry has its maximum geometric extension dimension. For example, such an elongated geometry can be rectangular, trapezoidal, triangular, oval, elliptical or of a similar shape.

[0074] The swirlers 45 are configured as recesses molded onto the outer side of the heat transfer tube 34. The swirlers 45 especially project into the tube inner space 39. The swirlers 45 are oriented at an inclination angle α with respect to the longitudinal direction 43. The inclination angle α is, for example, from 40° to 80°, preferably from 50° to 70°, more preferably 60°. However, any other inclination angle α can also be selected. All the swirlers 45 can have the same inclination angle α. However, each of the swirlers 45 can also have a different inclination angle α.

[0075] Here, the swirlers 45 on the bottom 35 and the swirlers 45 on the top cover 36 are preferably inclined in the opposite direction with respect to the longitudinal direction 43. This especially means that the swirlers 45 on the bottom 35 and the swirlers 45 on the top cover 36 are inclined with respect to the longitudinal direction 43 at an equal inclination angle α, but the signs of the inclination angle α of the swirlers 45 on the bottom 35 and the inclination angle α of the swirlers 45 on the top cover 36 are different from each other. In other words, the swirlers 45 on the bottom 35 and the swirlers 45 on the top cover 36 are arranged in a crossed or intersecting manner.

[0076] Furthermore, a plurality of protrusions 46 are molded onto the heat transfer tubes 34, which extend from the heat transfer tubes 34 into the tube outer space 40. The protrusions 46 form cavities that are fluidically connected to the tube inner space 39. The protrusions 46 are especially arranged only on the bottom 35 and the top cover 36. Within the corresponding heat transfer tube bundles 29, 30, 31, the heat transfer tubes 34 abut against each other at the protrusions 46.

[0077] The projections 46 are truncated cone-shaped or conical. The projections 46 serve to improve heat transfer, influence the exhaust gas flow and serve as a reservoir for the soot deposits that occur. In addition, the projections 46 serve to reinforce the heat transfer tube 34. In contrast to the vortex finders 45, the projections 46 do not extend into the tube interior 39, but into the tube exterior 40. As a result, the vortex finders 45 and the projections 46 are oriented in opposite directions.

[0078] The heat transfer tube 34 is preferably made of a composite material. Such a composite material may include a first material having a first thermal conductivity and a second material having a second thermal conductivity. Here, the first thermal conductivity is greater than the second thermal conductivity, the first material is disposed away from the tube inner space 39 and thus toward the tube outer space 40, and the second material is disposed toward the tube inner space 39 and thus away from the tube outer space 40.

[0079] As the first material, copper is used, for example. In this case, the second material may be stainless steel. Furthermore, brass may be used as the first material and stainless steel may be used as the second material. Copper or brass is connected to a stainless steel plate or applied to a stainless steel plate in the form of a coating to form the heat transfer tube 34. The use of such a composite material improves heat transfer.

[0080] Figure 9 and 10 The exhaust gas recirculation cooler 8 is shown in side view. Figure 9 and 10 .

[0081] Figure 9 The exhaust gas recirculation cooler 8 is shown in bypass mode or bypass mode Z1, whereas Figure 10 FIG. 2 shows the exhaust gas recirculation cooler 8 in cooling mode Z2. By means of the exhaust gas recirculation valve described above, the exhaust gas recirculation cooler 8 can be switched back and forth between bypass mode Z1 and cooling mode Z2. In operation of the exhaust gas recirculation cooler 8, the exhaust gas recirculation cooler 8 is cooled via the coolant inlet 21, 22. Figure 9 and 10 The cooling medium 47 indicated by the dashed arrow in FIG. 4 is supplied to the exhaust gas recirculation cooler. The cooling medium 47 flows through the outer tube space 40 surrounding the heat transfer tube bundle assembly 27 and the bypass line 28 and leaves the shell 9 through the discharge port 16.

[0082] In the bypass mode Z1, the exhaust gas recirculation valve is switched so that the exhaust gas 48 of the internal combustion engine 7 flows directly from the first cover plate 17 to the second cover plate 18 only through the bypass line 28. Since the bypass line 28 leads directly from the first cover plate 17 to the second cover plate 18, the exhaust gas 48 is guided through the housing 9 on the shortest possible path, so that the cooling medium 47 can only extract very little heat from the exhaust gas 48.

[0083] In cooling mode Z2, the exhaust gas recirculation valve is switched so that the exhaust gas 48 does not flow through the bypass line 28, but flows through the heat transfer tube bundle assembly 27. At this time, the exhaust gas 48 is distributed to each heat transfer tube 34, and the exhaust gas is turned multiple times within the housing 9. Since the heat transfer tube bundle assembly 27 has a plurality of heat transfer tubes 34, and the heat transfer tubes 34 include the vortex finders 45 as described above, the surface for conducting heat from the heat transfer tube bundle assembly 27 is large compared to the bypass line 28, so that a lot of heat is extracted from the exhaust gas 48 in cooling mode Z2. As a result, the exhaust gas 48 is cooled in cooling mode Z2.

[0084] Due to the vortex finder 45, the exhaust gas 48 vortexes in the heat transfer tube 34, so that carbon black deposits are not formed on the inside of the heat transfer tube 34 or at least the carbon black deposits are reduced. This avoids or at least delays the clogging of the tube space 39 by carbon black. In addition, the protrusions 46 can also be used as a reservoir for carbon black deposits that may be formed. In addition, the protrusions 46 also improve the heat transfer between the heat transfer tubes 34 and keep the heat transfer tubes 34 spaced apart so that the cooling medium 47 can flow through these heat transfer tubes 34 and thus can surround and flush the heat transfer tubes.

[0085] Although the invention has been described with reference to a few embodiments, it can be modified in many ways.

[0086] Reference numerals list

[0087] 1Motor Vehicle

[0088] 2 Body

[0089] 3Interior of motor vehicle

[0090] 4 Surrounding environment

[0091] 5 wheels

[0092] 6 wheels

[0093] 7 Internal combustion engine

[0094] 8 Exhaust Gas Recirculation Cooler

[0095] 9 Shell

[0096] 10 Sidewall

[0097] 11 Bottom

[0098] 12 Top Cover

[0099] 13 Hem

[0100] 14 Mounting Element

[0101] 15 Mounting Element

[0102] 16 Discharge Port

[0103] 17 Cover Plate

[0104] 18 Cover Plate

[0105] 19 Exhaust Gas Inlet

[0106] 20 Exhaust Gas Inlet

[0107] 21 Coolant Inlet

[0108] 22 Coolant Inlet

[0109] 23 Exhaust Gas Collector

[0110] 24 Exhaust Gas Duct

[0111] 25 Mounting Flange

[0112] 26 Connecting Pipe

[0113] 27 Heat Transfer Tube Bundle Assembly

[0114] 28 Bypass Pipeline

[0115] 29 Heat Transfer Tube Bundle

[0116] 30 Heat Transfer Tube Bundle

[0117] 31 Heat Transfer Tube Bundle

[0118] 32 Deflector Cap

[0119] 33 Deflector Cap

[0120] 34 Heat Transfer Tube

[0121] 35 Bottom

[0122] 36 Top Cover

[0123] 37 Side Wall

[0124] 38 Side Wall

[0125] 39 Space Inside the Tube

[0126] 40 Space Outside the Tube

[0127] 41 Spacer

[0128] 42 Spacer

[0129] 43 Vertical direction

[0130] 44 Weekly

[0131] 45 vortex generator

[0132] 46 bulge

[0133] 47 Cooling medium

[0134] 48 Exhaust

[0135] Z1 Bypass Mode

[0136] Z2 Cooling Mode

[0137] αTilt angle.

Claims

1. An exhaust gas recirculation cooler, the exhaust gas recirculation cooler being used in a motor vehicle (1) and having a heat transfer tube bundle assembly (27), through which exhaust gas (48) to be cooled can be guided, the heat transfer tube bundle assembly (27) having a plurality of heat transfer tubes (34), the heat transfer tubes (34) respectively surrounding a tube inner space (39), a vortex finder (45) for generating a vortex in the exhaust gas (48) guided through the heat transfer tube bundle assembly (27) being molded onto the heat transfer tube (34), the vortex finder (45) extending into the tube inner space (39), the vortex finders (45) respectively having an elongated geometric shape, and when viewed along the respective circumferential direction (44) of the heat transfer tube (34), the vortex finders (45) only partially surround the heat transfer tube (34).

2. The exhaust gas recirculation cooler according to claim 1, characterized in that: The vortex finder (45) is configured as a recess molded onto the outside of the heat transfer tube (34).

3. The exhaust gas recirculation cooler according to claim 1 or 2, characterized in that: The vortex finder (45) is arranged obliquely to the longitudinal direction (43) of the heat transfer tube (34).

4. The exhaust gas recirculation cooler according to claim 1 or 2, characterized in that: The vortex finder (45) has a rectangular geometry.

5. The exhaust gas recirculation cooler according to claim 4, characterized in that: The edges of the rectangular geometry are rounded.

6. The exhaust gas recirculation cooler according to claim 1 or 2, characterized in that: Protrusions (46) are molded onto the heat transfer tube (34), the protrusions extending away from the tube interior space (39) so that the protrusions (46) form cavities in fluid connection with the tube interior space (39).

7. The exhaust gas recirculation cooler according to claim 6, characterized in that: The protrusion (46) is truncated cone-shaped.

8. The exhaust gas recirculation cooler according to claim 6, characterized in that: Adjacent heat transfer tubes (34) are in contact with each other with their protrusions (46).

9. The exhaust gas recirculation cooler according to claim 1 or 2, characterized in that: The heat transfer tube (34) is a flat tube, so that the heat transfer tube (34) has a bottom (35), a top cover (36), a first side wall (37) connecting the bottom (35) and the top cover (36), and a second side wall (38) connecting the bottom (35) and the top cover (36), and the vortex finder (45) is only molded onto the bottom (35) and / or molded onto the top cover (36).

10. The exhaust gas recirculation cooler according to claim 1 or 2, characterized in that: The heat transfer tube bundle assembly (27) comprises a plurality of heat transfer tube bundles (29, 30, 31) and a plurality of turning caps (32, 33), wherein the turning caps fluidically connect the heat transfer tube bundles (29, 30, 31) to each other, and the heat transfer tube bundles (29, 30, 31) extend in parallel to each other.

11. The exhaust gas recirculation cooler according to claim 10, characterized in that There are exactly three heat transfer tube bundles (29, 30, 31) and exactly two turning caps (32, 33), and exactly one turning cap (32, 33) in each case fluidically connects exactly two heat transfer tube bundles (29, 30, 31) to each other.

12. The exhaust gas recirculation cooler according to claim 1 or 2, characterized in that: The heat transfer tube (34) is made of a composite material, the composite material comprising a first material having a first thermal conductivity and a second material having a second thermal conductivity, the first thermal conductivity being greater than the second thermal conductivity, the first material being arranged away from the space (39) in the tube, and the second material being arranged towards the space (39) in the tube.

13. The exhaust gas recirculation cooler according to claim 12, characterized in that The first material is copper or brass, and the second material is stainless steel.

14. The exhaust gas recirculation cooler according to claim 1 or 2, characterized in that: The motor vehicle is a passenger car.

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