DE102016211726B4 - exhaust gas cooler - Google Patents

Abstract

Exhaust gas cooler (10) with at least one distributor (16) made of aluminum or an aluminum alloy, which is arranged between an exhaust gas supply line and a heat exchanger and is surrounded by a limited space (34) through which a cooling medium can be guided, the heat exchanger having numerous largely parallel Has tubes, in particular flat tubes, through which the exhaust gas can flow, and the tubes through which the exhaust gas can flow are integrated into at least one assembly, which is integrated by at least one plate (30, 26, 42), and at least one plate (30, 26, 42 ) is connected to a jacket (22) of the heat exchanger, in particular soldered, in such a way that an intermediate space (32) remains for the flow of the cooling medium.

Description

TECHNICAL AREA

The invention relates to an exhaust gas cooler.

In order to reduce the pollutant emissions from internal combustion engines, it is customary to recirculate the exhaust gas to a certain extent and to feed it to the combustion chamber together with the air/fuel mixture. Depending on the operating state of the engine, the exhaust gas to be returned must be cooled.

STATE OF THE ART

The U.S. 2008/0202724 A1 relates in this regard to an exhaust gas cooler made of unspecified material which, seen in the direction of flow, has an exhaust gas supply line, a distributor, parallel tubes connected thereto, a collector and an exhaust gas discharge line. At the junction between both the header and the distributor and the numerous parallel tubes, there is a supply line for coolant which flows around the parallel tubes, bounded by a jacket, and exits the heat exchanger at a point along the length of the tubes.

The DE 10 2009 028 487 A1 relates to an exhaust gas cooler which is at least partially made of extruded aluminum.

PRESENTATION OF THE INVENTION

Against this background, the invention is based on the object of creating an exhaust gas cooler which is improved with regard to the thermal load on the individual components and/or surrounding components.

This problem is solved by the exhaust gas cooler described in claim 1.

Accordingly, the exhaust gas cooler according to the invention has at least one distributor made of aluminum or an aluminum alloy, which is arranged between an exhaust gas supply line and a heat exchanger or exchanger and surrounded by a limited space through which a cooling medium can be guided. The use of aluminum or an aluminum alloy offers cost advantages over the use of steel and, due to the higher thermal conductivity of aluminum, better cooling performance. However, any components, especially those that take on structural tasks and therefore must not be significantly weakened, may only be exposed to heating to a limited extent.

In the exhaust gas cooler according to the invention with a distributor made of aluminum, it is therefore critical to keep the components that come into direct contact with the extremely hot exhaust gas within tolerable temperature ranges. This means maximum temperatures of around 200 to 250 °C, while the exhaust gas can be supplied at up to 800 °C.

According to the invention, excessive heating of the critical components on the inflow side is avoided in that the distributor is surrounded by a limited space through which a cooling medium can be guided. In other words, the distributor is cooled directly by a cooling medium, for example water, flowing around it. The component that delimits the space around the distributor can be referred to as the distributor jacket and can have at least one inlet for the cooling medium. As described in more detail below, the manifold shell may be connected to a generally cylindrical or prismatic shell that gives off numerous parallel tubes through which the exhaust gas flows. On the outlet side there is a jacket similar to that on the inflow side, which can be referred to as a collector jacket and contains at least one outlet for the cooling medium.

On the critical inflow side, the flow conditions are set in such a way that cooling of the critical distributor is first ensured before the cooling medium continues to flow into the area of the numerous parallel tubes. In this way, overheating of the distributor, which is critical with regard to temperature, can be avoided, and this advantageously applies equally to surrounding components.

Alternatively or additionally, the above-mentioned task is solved by an exhaust gas cooler, which can be designed as described above and has at least one fastening flange, preferably made of aluminum or an aluminum alloy, which is thermally conductively connected to a limited space through which a cooling medium can be guided. Such an inflow-side fastening flange is also temperature-critical and is advantageously cooled by the measure according to the invention. Since the flange is typically located outside of the exhaust gas feed line and the distributor jacket, it is ensured according to the invention, for example by an extensive contact surface between the fastening flange and the distributor jacket, that adequate heat dissipation takes place. As a result, the cooling effect due to the flow of cooling medium through the limited space on the adjacent fasteners expansion flange so that it is adequately cooled and, moreover, unwanted heat transfer to surrounding components can be restricted. This applies in particular to that preferred embodiment in which the fastening flange is made of aluminum or an aluminum alloy. However, the above advantages can also be used when the mounting flange is made of a different material, such as. B. steel or a suitable plastic. In the case of using steel for any components of the cooler according to the invention, such as. B. the distributor and / or the mounting flange, steel as a material offers the advantage of a larger cooling surface. In this context, it should also be considered that the measure according to the invention allows the exhaust gas, which is particularly hot at this point, to be already cooled in the distributor. If the hot exhaust gas directly hits a particularly large heat-transferring surface in the "core" of the exhaust gas cooler that is connected to the distributor, there is a risk that the surrounding coolant will start to boil here. Such critical temperatures in the area of the core of the exhaust gas cooler can advantageously be avoided by the measure according to the invention.

With regard to the directions of flow in the heat exchanger, it should be mentioned that this can be designed as a countercurrent or cocurrent heat exchanger. Furthermore, a combination of both types is possible, for example by providing at least one outflow or inflow for a cooling medium along its longitudinal extent, and accordingly at least one inflow or outflow is located in the region of each end.

As already mentioned, it has proven to be advantageous for the heat exchanger to provide numerous largely parallel tubes, in particular flat tubes, through which the exhaust gas can flow. Several tubes can be integrated in a “stacked” manner into a single component, for example an extruded one. However, it is also conceivable to design the tubes with a round or oval cross section, which can also have the indentations described below. In addition, both the tubes with the last-described cross-section and the previously mentioned flat tubes can have turbulence-generating elements on the gas side and/or a turbulence-generating geometry in the form of, for example, indentations and/or indentations. Individual tubes or a combination of several tubes can be designed as an extruded profile. Likewise, numerous parallel flow paths for the exhaust gas to be cooled can be formed by an assembly whose components can be soldered to one another, for example. A distributor and/or collector, numerous parallel metal sheets with possibly corrugated fins arranged between them in order to delimit individual flow channels from one another, and two half-shells enclosing the plates and fins can be provided as components of such an assembly.

For the handling within the framework of the assembly of the exhaust gas cooler according to the invention, it offers advantages that the pipes through which the exhaust gas can flow are integrated into at least one module.

The use of at least one plate is particularly advantageous for this purpose, since this is a particularly simple component with which the flow of the cooling medium can also be adjusted from the limited space around the distributor into the area with the numerous pipes through which exhaust gas flows.

Preferred developments of the exhaust gas cooler according to the invention are described in the further claims.

It is preferred for the mounting flange to be substantially disc-shaped and a manifold shell surrounding the confined space to have a disc-shaped portion at least partially in contact with the mounting flange. The disk-shaped fastening flange can have a certain thickness, for example a few millimeters up to 2 cm, in order to be able to form bores along its thickness for screwing in fastening screws. The outline of the mounting flange can be chosen as desired, but can be largely elliptical, for example, so that it surrounds the exhaust gas feed line in the area of the short axis of the ellipse, and space is available at the ends of the long axis of the ellipse for the formation of the mounting holes described. The disk-shaped section of the distributor shell can be an “axial cover” so to speak, which surrounds the exhaust gas feed line in the radial direction and defines the limited space in the axial direction.

In the first simulations, it has proven to be particularly advantageous to provide the supply of cooling medium largely exclusively in the area of the distributor. In other words, the coolant first flows around the distributor before it can continue to flow into the area of the numerous parallel tubes. This ensures particularly reliable cooling of the critical distributor. In other words, the coolant in the area that the numerous having parallel tubes, only after having previously flowed through the limited space around the manifold. With regard to the measure described above, as well as in particular for the features of claims 6 and 10 to 12, it should be emphasized that these also develop their advantages independently of the material of the distributor and are therefore also to be regarded as the subject of the present application independently of this material.

Indentations are preferably provided on at least one tube and on at least one outside thereof, particularly preferably on all tubes and on at least two outsides, in order to increase the heat transfer surface. The indentations can, for example, be circular, to a certain extent designed as small "hills" on the inside of the tube, but they can also be rectangular or square, as "pyramids" in the broadest sense on the inside, or with a longitudinal extension, possibly arc-shaped, thus as (arc-shaped) Ribs may be provided on the inside. In this context it should be mentioned that one or more of the tubes mentioned herein or "stacked" arrangements of the modules described below as extruded or -cast profiles according to the filed on the same day by the applicant entitled "Extruded profile and method for its manufacture". Registration is described. In particular, an exhaust gas cooler with one or more of the extruded profiles described there with all of the features described there in any combination and in all embodiments is to be regarded as the subject matter of the present application.

This effect can be achieved particularly efficiently in that the assembly is connected, in particular soldered, to a jacket around the numerous tubes in such a way that spaces remain for the flow of the cooling medium.

For the flow of the cooling medium in the heat exchanger, which has the numerous parallel tubes, it has also proven to be advantageous to provide at least one means of flow deflection and/or deflection, such as a baffle plate, to ensure that the cooling medium remains there for a sufficiently long time Ensure cooling medium in this area. This achieves adequate heat absorption by the cooling medium and correspondingly adequate cooling of the exhaust gas.

As mentioned, a collector for the exhaust gas that has flowed through the numerous tubes is preferably provided downstream of the heat exchanger, the collector being connected to an exhaust gas discharge line. In order to standardize the components involved, it is preferred for this collector to be of substantially the same design as the manifold.

Similarly, it is preferred for a collector jacket, which can be provided around the collector, so that the space around the collector can also be flowed through by cooling medium, that it is essentially identical to the distributor jacket.

The positive effects according to the invention in terms of costs and heat dissipation can be achieved to a particular extent and can also be combined with an advantageous weight saving if the jacket is wrapped around the numerous parallel tubes and/or the distributor jacket and/or the collector and/or or the collector jacket and/or the numerous parallel tubes, and/or a downstream fastening flange and/or at least one plate, and preferably the entire exhaust gas cooler are made of aluminum or an aluminum alloy. The jacket in particular, but also one or more of the other components mentioned, can also be made of a suitable plastic. In this case, a core of the cooler made of metal, which essentially has the other components mentioned above, can be sealed to form a plastic jacket by means of seals.

character list

• 1 eine Schnittansicht des erfindungsgemäßen Abgaskühlers in einer ersten Ausführungsform;
• 2 eine Querschnittsansicht der ersten Ausführungsform; und
• 3 eine Längsschnittansicht einer zweiten Ausführungsform des erfindungsgemäßen Kühlers.

Preferred exemplary embodiments of the invention are explained in more detail below with reference to the drawings. Show it:

• 1 a sectional view of the exhaust gas cooler according to the invention in a first embodiment;
• 2 a cross-sectional view of the first embodiment; and
• 3 a longitudinal sectional view of a second embodiment of the cooler according to the invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

the inside 1 The exhaust gas cooler 10 shown initially has on its inflow side (in 1 left) has a mounting flange 12 with which the exhaust gas cooler 10 can be connected to an exhaust gas pipe (not shown). For this are in 1 In the upper and lower area, fastening openings 14 can be seen, which give the fastening flange an elongated (according to 1 with a longitudinal extension from top to bottom) or in white test sense give elliptical shape. In the area of the short axis of the ellipse, the mounting flange 12 is slightly wider (in 1 the direction largely perpendicular to the plane of the drawing) as the approximately central opening that allows an exhaust gas supply. In the vicinity of the ends of the long axis of the ellipse, the attachment openings 14 are provided, and the areas between the ends of the long and short axes of the ellipse may be made substantially straight, unlike the actual geometric shape of an ellipse.

As in 1 As can be seen, the mounting flange 12 has a thickness (in 1 measured from left to right) of a few millimeters or 1 to 2 centimeters. In this case, the thickness is preferably essentially constant over the entire extent of the fastening flange 12 .

Both an essentially cylindrical "collar" of an (exhaust gas) distributor 16 and of a distributor jacket 18 extend through the preferably circular opening approximately in the middle of the fastening flange 12. The distributor 16 opens essentially in a funnel shape, starting from the described collar, in order to enable a distribution of the supplied exhaust gas to numerous parallel pipes which are connected to this in the direction of flow. The distributor jacket 18 essentially surrounds the distributor 16 and thereby defines a limited space 34 with an inflow 20 for cooling medium, in particular cooling water. A substantially radially extending area, previously referred to as disk-shaped, which can also be referred to as flange-like, and is in extensive, planar contact with the fastening flange 12 , adjoins the collar of the distributor jacket 18 . As explained in more detail below, the flow through the space 34 between the distributor 16 and the distributor jacket 18 not only allows the distributor 16 to be cooled, but also the adjacent fastening flange 12 Excessive heat transfer to a flange (not shown) of the exhaust gas supply pipe, which is attached to the mounting flange 12, can be avoided.

The distributor casing 18 extends from the above-mentioned flange-like area essentially cylindrically or, in the example shown, as more precisely in FIG 2 to recognize, prismatic with rounded corners with a rounded transition to the flange-like area. Adjoining the distributor jacket 18 is a jacket 22 which is equally cylindrical or prismatic in shape and surrounds the area of the numerous parallel tubes. In the example shown, this jacket 22, which can also be referred to as a shell or housing, has an outlet 24 for coolant. At the end of the numerous tubes, viewed in the direction of flow, a plate 26 is arranged, which at this end delimits the space through which the coolant flows. For this purpose, in the embodiment shown, the plate 26 is bent or beveled counter to the direction of flow in order to ensure a fluid-tight connection to the casing 22, for example by soldering. In the embodiment shown, downstream of the described plate 26, also connected to it in a suitable manner, for example by soldering, there is an (exhaust gas) collector 28, in which the individual exhaust gas flows from the numerous pipes for discharge (in 1 to the right) are collected.

On the (in 1 left) inflow side, a plate 30 can also be seen, which is bent counter to the direction of flow and, in the example shown, is connected to the distributor jacket 18 on only three sides, for example soldered.

This is supplementary in 2 recognizable. Due to the position of the cross section shown approximately at the connection point between the mentioned components, the distributor jacket 18, the plate 30 and the distributor 16 can be seen from the outside inwards. For the plate 30 results from 2 Furthermore, that these on three sides, according to 2 is connected to the distributor jacket 18 on the left, right and above, so that coolant that enters the space 34 (cf. 1 ) between the distributor 16 and the distributor shell 18 can only flow through the gap 32 in the lower region into the region of the numerous parallel tubes. This ensures sufficient retention of the coolant in the limited space in 1 indicated at 34, provided to cool the manifold 16 and/or the mounting flange 12 adjacent to the manifold shell 18.

In 2 It can also be seen that in the embodiment shown the numerous parallel tubes are "stacked" in four configurations in the example shown. In the case shown, these four (parallel) modules can be formed, for example, by extrusion, so that the entire “stack” of flat tubes can be produced efficiently. In 2 it can also be seen how indentations 36 formed on the outside (cf. 1 ) extend inwards as a “hill” to increase the heat-transfer area. As mentioned above, the circular indentations can have other shapes. Due to the numerous and, as can be seen, staggered indentations with regard to the individual rows or "columns", in a (not shown provided) sectional view of the walls of the tubes a kind of wavy shape.

With reference to 1 it should be added that one or more flow deflections or deflections 38 can be provided, which are referred to below as baffles and, in the illustrated example, ensure a substantially (lying) S-shaped flow in the vicinity of the numerous parallel tubes. In particular, the in 1 indicated baffles 38 are located adjacent to and between the "stacks" of tubes to provide the flow of the described shape throughout the spaces between the "stacks". As also in 1 As can be seen, the cooling medium flows through the inflow 20 into the limited space 34 and, as mentioned, first cools the distributor 16 and the fastening flange 12 there. Through the intermediate space 32 (cf. 2 ) the cooling medium continues to flow into the vicinity of the numerous parallel tubes. The space in which the coolant can move is limited on the outside by the jacket 22, and the baffles 38, as mentioned, ensure a meandering flow in a certain way, which ensures that the coolant remains for a sufficiently long time in the vicinity of the parallel tubes and ensure sufficient heat absorption. At the downstream end, the coolant exits the space between the shell 22 and the multiple parallel tubes through the drain 24. The cooled exhaust gas after exiting the multiple parallel tubes is collected by the collector 28 and routed from there. To the embodiment of 1 and 2 it should be noted that exhaust gas and coolant flow essentially in the same direction, but this can also be reversed. Furthermore, at the downstream end (with respect to the exhaust gas) there may be a second inflow (substantially instead of the outflow 24 shown) and one or more outflows may be provided along the extension of the parallel tubes, particularly in a central region. Furthermore, any inflows and outflows can also occur in places other than in 1 to be recognizable, for example on the underside and/or the sides (according to 2 left or right). In this case, in order to achieve the desired flow of the coolant, the baffles 38 are adjusted in a suitable manner.

The mounting flange 12 may be (laser) cut or stamped from a suitably thick sheet of aluminum or aluminum alloy. The distributor 16 and/or the collector 28 and/or the distributor casing 18 and/or the collector casing 40 and/or the at least one plate 26, 30, 42 can be deep-drawn from the materials mentioned. However, for all individual parts of the exhaust gas cooler 10 according to the invention that are made of aluminum, it is also possible to produce them by casting.

In the 3 The second embodiment shown in longitudinal section differs from the first embodiment only in the area of (in 3 right) outlet side and with regard to the guide plate 38, which in this embodiment is the only one provided approximately in the middle of the longitudinal extent of the parallel tubes and the coolant inlet 20 and outlet 24 opposite. On the outlet side, however, it can be seen that the collector 28 largely corresponds to the inlet-side distributor 16 and the collector casing 40 largely corresponds to the distributor casing 18 . This applies equally to the outlet-side plate 42 and an outlet-side fastening flange 44. Thus, between collector 28 and collector jacket 40 is also only in accordance with FIG 3 lower area a fluid passage. As a result, the necessary individual parts can be standardized in an advantageous manner and the overall manufacturing effort for the exhaust gas cooler 10 according to the invention can be reduced. It goes without saying that all the features and modifications described above and below can also be applied to the first embodiment.

Claims (11)

Exhaust gas cooler (10) with at least one distributor (16) made of aluminum or an aluminum alloy, which is arranged between an exhaust gas feed line and a heat exchanger and is surrounded by a limited space (34) through which a cooling medium can be guided, wherein the heat exchanger has numerous largely parallel tubes, in particular flat tubes, through which the exhaust gas can flow, and the pipes through which the exhaust gas can flow are integrated into at least one assembly, which is integrated by at least one plate (30, 26, 42), and at least one plate (30, 26, 42) is connected, in particular soldered, to a jacket (22) of the heat exchanger in such a way that an intermediate space (32) remains for the flow of the cooling medium. exhaust gas cooler after claim 1 , With at least one fastening flange (12) preferably made of aluminum or an aluminum alloy, which is thermally conductively connected to a boundary of a space (34) through which a cooling medium can be guided. Exhaust gas cooler (10) with at least one fastening flange (12), preferably made of aluminum or an aluminum alloy, which is thermally conductively connected to a boundary of a space (34). through which a cooling medium can be guided, the heat exchanger having numerous largely parallel tubes, in particular flat tubes, through which the exhaust gas can flow, and the tubes through which the exhaust gas can flow are integrated into at least one assembly group, which is formed by at least one plate (30, 26, 42) is integrated, and at least one plate (30, 26, 42) is connected, in particular soldered, to a jacket (22) of the heat exchanger in such a way that an intermediate space (32) remains for the flow of the cooling medium. exhaust gas cooler after claim 2 , characterized in that the fastening flange (12) is largely disc-shaped and a distributor casing (18) delimiting the space (34) has a largely disc-shaped section which is at least partially in planar contact with the fastening flange (12). Exhaust gas cooler according to one of the preceding claims, characterized in that the supply of cooling medium takes place largely exclusively in the region of the distributor (16). Exhaust gas cooler according to one of the preceding claims, characterized in that the tubes have numerous indentations (36) on their outsides. Exhaust gas cooler according to one of the preceding claims, characterized in that at least one guide plate (38) is provided in the heat exchanger. An exhaust gas cooler as claimed in any one of the preceding claims, further comprising a header (28) downstream of the heat exchanger shaped substantially conformably with the manifold (16). Exhaust gas cooler according to one of the preceding claims, characterized in that the confined space (34) is surrounded by a distributor jacket (18) which is substantially identical to a collector jacket (40) which surrounds a collector-side confined space around the collector (28). . Exhaust gas cooler according to one of the preceding claims, characterized in that the jacket (22) and / or the collector (28), and / or the distributor and / or the distributor jacket (18) and / or the collector jacket (40) and / or the parallel tubes and/or a downstream attachment flange and/or at least one plate (30, 26, 42) made of aluminum or an aluminum alloy. Exhaust gas cooler according to one of the preceding claims, characterized in that it is made entirely of aluminum or an aluminum alloy.

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