DE102016211726A1 - exhaust gas cooler - Google Patents

Abstract

An exhaust gas cooler (10) has at least one distributor (16) 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.

Description

TECHNICAL AREA

The invention relates to an exhaust gas cooler.

In order to reduce the pollutant emissions of internal combustion engines, it is common to recirculate the exhaust gas to some extent and supply it to the combustion chamber together with the air / fuel mixture. Depending on the operating condition of the engine, the exhaust gas to be recirculated must be cooled in this case.

STATE OF THE ART

The US 2008/0202724 A1 in this respect relates to an exhaust gas cooler from unspecified material, which, seen in the flow direction, an exhaust gas supply line, a distributor, adjoining parallel pipes, a collector and an exhaust gas outlet. At the juncture between both the header and the manifold and the numerous parallel tubes, there is provided a coolant supply line which bypasses the parallel tubes defined by a jacket and leaves the heat exchanger at a location 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 has for its object to provide an exhaust gas cooler, which is improved in terms of thermal stress on the individual components and / or surrounding components.

The solution to this problem is achieved by the exhaust gas cooler described in claim 1.

Accordingly, the exhaust gas cooler according to the invention comprises at least one distributor made of aluminum or an aluminum alloy, which is arranged between an exhaust gas feed line and a heat exchanger or transformer and surrounded by a limited space through which a cooling medium can be guided. The use of aluminum or an aluminum alloy offers cost benefits over the use of steel, as well as better cooling performance due to the higher thermal conductivity of aluminum. In this case, however, any components, in particular those that take on structural tasks and must therefore not be appreciably weakened, may only be exposed to a limited extent to heating.

Thus, in the exhaust gas cooler according to the invention with an aluminum manifold, which is to be understood as aluminum and aluminum alloy in the following, it is critical to keep the components directly in contact with the extremely hot exhaust in compatible temperature ranges. This means maximum temperatures of about 200 to 250 ° C, while the exhaust gas can be fed up to 800 ° C.

According to the invention, an 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 immediately by flowing around it by a cooling medium, for example water. The component which delimits the space around the distributor can be referred to as a distributor jacket and can have at least one inlet for the cooling medium. As described in more detail below, the distributor shell may be connected to a substantially cylindrical or prismatic shell which emits numerous parallel tubes through which the exhaust gas flows. On the outlet side there is a similar jacket as on the inflow side, which can be referred to as a collector shell and contains at least one outlet for the cooling medium.

On the critical inflow side, the flow conditions are adjusted so that first cooling of the critical distributor is ensured before the cooling medium continues to flow into the region of the numerous parallel tubes. Thus, overheating of the temperature critical manifold can be avoided, and this advantageously applies equally to surrounding components.

Alternatively or additionally, the solution of the above object by an exhaust gas cooler, which may be designed as described above and at least one mounting 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. Also, such an inflow-side mounting flange is temperature-critical and is cooled by the inventive measure in an advantageous manner. Since the flange is typically located outside the exhaust gas supply line and the distributor casing, according to the invention, for example, an extensive contact surface between the fastening flange and the distributor casing ensures that sufficient heat dissipation takes place. As a result, the cooling effect can be extended as a result of the flow through the limited space with cooling medium on the adjoining mounting flange, so that this is sufficiently cooled and, moreover, an undesirable heat transfer to surrounding components can be limited. This is especially true for the preferred embodiment in which the mounting flange is made of aluminum or an aluminum alloy. However, the advantages mentioned can also be used when the mounting flange made of a different material, such. B. steel or a suitable plastic is executed. In the case of using steel for any components of the cooler according to the invention, such. As 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 inventive measure the particularly hot exhaust gas can be already cooled in the manifold by the measure. Namely, if the hot exhaust gas directly strikes a particularly large heat transfer surface which is present in the "core" of the exhaust gas cooler adjacent to the distributor, there is the risk that the surrounding coolant will start to boil here. Such critical temperatures in the region of the core of the exhaust gas cooler can be advantageously avoided by the measure according to the invention.

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

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

It is preferable for the attachment flange to be substantially disc-shaped, and for a distributor shell surrounding the limited space to have a disc-shaped portion at least partially in contact with the attachment flange. The disc-shaped mounting flange may have a certain thickness, for example a few millimeters up to 2 cm, to be able to form bores for screwing in fastening screws along its thickness. The outline of the mounting flange is arbitrary, but may for example be substantially elliptical, so that in the region of the short axis of the ellipse surrounds the exhaust gas supply, and at the ends of the long axis of the ellipse space for the formation of the mounting holes described is available. The disk-shaped section of the distributor casing can effectively be an "axial cover" which surrounds the exhaust gas supply line in the radial direction and defines the limited space in the axial direction.

In the case of first simulations, it has proved to be particularly advantageous to provide the supply of cooling medium largely exclusively in the region of the distributor. In other words, the cooling medium first flows around the distributor before it can continue to flow into the area of the numerous parallel tubes. This ensures a particularly reliable cooling of the critical distributor. In other words, the coolant can only get into the area having the numerous parallel tubes after having previously passed through the limited space around the manifold. To the measure described above, as well as in particular for the features of claims 6 and 10 to 12 stressed that they also develop their advantages regardless of the material of the distributor and thus are to be regarded as independent of this material as subject of the present application.

As already mentioned, it has proved 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 "stacked" into a single, for example, extruded component. However, it is also conceivable to carry out the tubes with a round or oval cross-section, which may equally well have the recesses described below. In addition, both the pipes with the last-described cross-section, as well as the above-mentioned flat tubes on the gas side turbulence generating elements and / or a turbulence generating geometry, in the form of, for example depressions and / or indentations. Individual tubes or a combination of several tubes can be designed as 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 together, for example. As components of such an assembly, a manifold and / or collector, numerous parallel plates arranged therebetween, optionally wave-shaped fins to separate individual flow channels from each other, as well as two plates and fins enclosing half-shells can be provided.

Preferably, depressions are provided on at least one tube and on at least one outer side thereof, particularly preferably on all tubes and on at least two outer sides, in order to increase the heat transfer area. The depressions can, for example, circular, in a sense as a small "hill" on the However, they can also be rectangular or square, as in the broadest sense "pyramids" on the inside, or possibly with a longitudinal extent arcuate, thus be provided as (arcuate) ribs on the inside. In this regard, it should be noted that one or more of the herein-mentioned tubes or "stacked" assemblies of the modules described below are extruded or cast profiles as filed on the same day by the Applicant entitled "Extruded profile and method of making the same" Application is described. In particular, an exhaust gas cooler with one or more of the extruded profiles described therein with all the features described therein in any combination and in all embodiments is to be regarded as an object of the present application.

For handling in the context of assembly of the exhaust gas cooler according to the invention, it offers advantages if the pipes through which the exhaust gas can flow are integrated into at least one subassembly.

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

This effect can be achieved particularly efficiently by the assembly being connected, in particular soldered, to a shell around the numerous tubes such that gaps for the flow of the cooling medium remain.

For the flow of the cooling medium in the heat exchanger having the numerous parallel tubes, it has also proven to be advantageous to provide at least one means for Strömungsab- and / or deflection, such as a baffle to a sufficiently long whereabouts of Ensure cooling medium in this area. As a result, an adequate heat absorption by the cooling medium and a correspondingly adequate cooling of the exhaust gas is achieved.

As mentioned, downstream of the heat exchanger, there is preferably provided a collector for the exhaust gas which has passed through the numerous tubes, the collector being connected to an exhaust gas outlet. In order to unify the components involved, it is preferred for this collector to be designed substantially in unison with the manifold.

Similarly, for a collector shell, which may be provided around the collector so that the space around the collector of cooling medium can be flowed through, it is preferred that it be substantially identical to the distributor jacket.

The positive and cost-effective effects according to the invention can thus be achieved to a particular extent and, in addition, combined with an advantageous weight saving when the jacket around the numerous parallel tubes and / or the distributor jacket, and / or the collector and / or or the collector shell and / or the numerous parallel tubes, and / or a downstream flange and / or at least one plate, and preferably the entire exhaust gas cooler made of aluminum or an aluminum alloy. In particular, the jacket, 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 metal cooler, which has substantially the above-mentioned other components, can be sealed to a plastic jacket by means of seals.

BRIEF DESCRIPTION OF THE DRAWINGS

Hereinafter, preferred embodiments of the invention will be explained in more detail 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 in 1 illustrated exhaust gas cooler 10 points first at its inflow side (in 1 left) a mounting flange 12 on, with the exhaust gas cooler 10 can be connected to a (not shown) exhaust pipe. These are in 1 in the upper and lower area mounting holes 14 to recognize the mounting flange an elongated (in accordance with 1 with a longitudinal extension from top to bottom) or give in the broadest sense elliptical shape. In the area of the short axis of the ellipse is the mounting flange 12 slightly wider (in 1 the direction largely perpendicular to the drawing plane) than the approximately central opening, which allows an exhaust gas supply. Near the ends of the long axis of the ellipse are the mounting holes 14 provided, and the areas between the ends of the long and the short axis of the ellipse, unlike the actual geometric shape of an ellipse, be made largely straight.

As in 1 to recognize, has the mounting flange 12 a thickness (in 1 measured from left to right) of a few millimeters or 1 to 2 centimeters. Here, the thickness is preferably over the entire extent of the mounting flange 12 essentially consistent.

Through the preferably circular opening approximately in the middle of the mounting flange 12 extends both a substantially cylindrical "collar" of an (exhaust) manifold 16 as well as a distribution jacket 18 , The distributor 16 opens in a substantially funnel-shaped manner from the described collar, in order to allow a distribution of the supplied exhaust gas to numerous parallel tubes, which follow in the flow direction thereto. The distribution jacket 18 essentially surrounds the distributor 16 and thereby defines a limited space 34 with a tributary 20 for cooling medium, in particular cooling water. On the collar of the distribution jacket 18 is followed by a substantially radially extending, previously designated as disk-shaped area, which can also be referred to as a flange, and extensively in surface contact with the mounting flange 12 stands. As explained in more detail below, thereby allowing the flow through the room 34 between the distributor 16 and the distribution jacket 18 not just the cooling of the distributor 16 , but also the adjacent mounting flange 12 , As a result, the said components can be efficiently cooled, and it can also be avoided excessive heat transfer to a (not shown) flange of the exhaust gas supply line, which on the mounting flange 12 is attached.

The distribution jacket 18 extends from the above-mentioned flange-like area substantially cylindrical or, in the example shown, as more fully in 2 recognizable, prismatic with rounded corners with a rounded transition to the flange-like area. To the distribution jacket 18 closes a coat 22 which is equally cylindrical or prismatic 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, a drain 24 for coolant on. At the end of the numerous pipes, seen in the direction of flow, is a plate 26 arranged, which limits the flowed through by the coolant space at this end. This is the plate 26 bent or folded in the embodiment shown opposite to the flow direction to a fluid-tight connection with the jacket 22 , for example by soldering. In the embodiment shown, downstream of the described plate 26 , also suitably, for example by soldering, associated therewith, an (exhaust) collector 28 present in which the single exhaust gas flows from the numerous pipes for discharge (in 1 to the right).

On the (in 1 left) upstream side, is also a plate 30 recognizable, which is folded against the flow direction and in the example shown on only three sides with the distributor shell 18 connected, for example, is soldered.

This is supplementary in 2 recognizable. Due to the position of the cross section shown approximately at the junction between said components, are from outside to inside of the distributor shell 18 , the plate 30 and the distributor 16 to recognize. For the plate 30 turns out 2 furthermore, that this on three sides, according to 2 left, right and above with the distribution jacket 18 connected so that coolant enters the room 34 (see. 1 ) between the distributor 16 and the distribution jacket 18 is fed, only through the gap 32 in the lower part can flow into the area of numerous parallel tubes. In this way, a sufficient fate of the coolant in the limited space, in 1 With 34 designated, ensured to the distributor 16 and / or the distributor shell 18 adjacent mounting flange 12 to cool.

In 2 It will also be appreciated that in the embodiment shown, the numerous parallel tubes in the example shown are "stacked" in four arrangements. These in the case shown four (parallel) modules can be formed for example by extrusion, so that the entire "stack" of flat tubes can be efficiently produced. In 2 It can also be seen how wells formed on the outside 36 (see. 1 ) extend inward as a "hill" to increase the heat transmitting area. As mentioned above, the circular recesses may have other shapes. Due to the numerous and, as can be seen, with respect to the individual rows or "columns" arranged recesses results in a (not shown) sectional view of the walls of the tubes a certain extent wavy shape.

With reference to 1 be added that one or more Strömungsab- or deflections 38 may be provided, which are hereinafter referred to as baffles and in the shown to provide for a substantially (horizontal) S-shaped flow in the vicinity of the numerous parallel tubes. In particular, the in 1 indicated baffles 58 next to and between the "stacks" of pipes to provide in the spaces between the "stacks" everywhere for the flow with the described shape. Like also in 1 recognizable, namely, the cooling medium flows through the inflow 20 in the limited space 34 and cools there, as mentioned, first the distributor 16 and the mounting flange 12 , Through the gap 32 (see. 2 ), the cooling medium continues to flow into the vicinity of the numerous parallel tubes. The space in which the coolant can move is out through the shell 22 limited, and the baffles 38 ensure, as mentioned, by a somewhat meandering flow, which ensures a sufficiently long fate of the cooling medium in the vicinity of the parallel tubes and sufficient heat absorption. At the downstream end, the coolant leaves the space between the jacket 22 and the numerous parallel pipes through the drain 24 , The cooled exhaust gas is released from the numerous parallel tubes through the collector 28 collected and forwarded from there. To the embodiment of 1 and 2 It should be noted that exhaust gas and coolant flow in substantially the same direction, but this can also be reversed. Further, at the downstream end (with respect to the exhaust gas), there may be a second inflow (substantially in lieu of the drain shown 24 ), and one or more drains may be provided along the extent of the parallel tubes, particularly in a central region. Furthermore, any inflows and outflows can also be in other places than in 1 be provided to recognize, for example, on the bottom and / or sides (according to 2 left or right). In order to achieve the desired flow of the coolant, in this case, the baffles 38 adapted as appropriate.

The mounting flange 12 can be cut or stamped from a correspondingly thick aluminum or aluminum alloy sheet (laser). The distributor and / or the collector and / or the distributor casing and / or the collector casing and / or the at least one plate may be deep drawn from the said materials. For all individual parts made of aluminum of the exhaust gas cooler according to the invention, however, it is also possible to produce them by casting.

In the 3 shown in longitudinal section second embodiment differs from the first embodiment only in the area of (in 3 right) outlet side and with respect to the baffle 38 , which in this embodiment is the only one approximately in the middle of the longitudinal extent of the parallel tubes and the coolant supply. 20 and drain 24 is provided opposite. On the exhaust side, however, it can be seen that the collector 28 largely coincident with the inlet side manifold 16 , and the collector's coat 40 largely coincident with the distribution jacket 18 is designed. This applies equally to the outlet side plate 42 and an outlet side mounting flange 44 , Thus, is located between collectors 28 and collector's coat 40 also only in accordance with the 3 lower area a fluid passage. As a result, the necessary items can be standardized in an advantageous manner, and the manufacturing cost of the exhaust gas cooler according to the invention 10 be reduced. It is understood that all the features and modifications described above and below are also applicable to the first embodiment.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2008/0202724 A1 [0003]
• DE 102009028487 A1 [0004]

Claims (14)

Exhaust gas cooler ( 10 ) with at least one distributor ( 16 ) of aluminum or an aluminum alloy, which is arranged between an exhaust gas feed line and a heat exchanger and of a limited space ( 34 ) is surrounded, through which a cooling medium is feasible. Exhaust gas cooler, in particular according to claim 1, with at least one mounting flange ( 12 ) preferably made of aluminum or an aluminum alloy, the heat-conducting with a limitation ( 18 ) of a room ( 34 ) is connected, through which a cooling medium is feasible. Exhaust cooler according to claim 2, characterized in that the mounting flange ( 12 ) is largely disc-shaped and the space ( 34 ) limiting distribution jacket ( 18 ) has a largely disc-shaped portion which at least partially with the mounting flange ( 12 ) is in surface contact. Exhaust gas cooler according to one of the preceding claims; characterized in that the supply of cooling medium substantially exclusively in the region of the distributor ( 16 ) he follows. Exhaust gas cooler according to one of the preceding claims, characterized in that the heat exchanger has numerous largely parallel tubes, in particular flat tubes, which can be flowed through by the exhaust gas. Exhaust gas cooler according to claim 5, characterized in that the tubes on their outsides numerous depressions ( 36 ) exhibit. Exhaust cooler according to claim 5 or 6, characterized in that the flow-through of the exhaust pipes are integrated into at least one assembly. Exhaust cooler according to claim 7, characterized in that at least one assembly by at least one plate ( 30 . 26 . 42 ) is integrated. Exhaust gas cooler according to claim 8, characterized in that at least one plate ( 30 . 26 . 42 ) with a coat ( 22 ) of the heat exchanger is connected in such a way, in particular soldered, that a gap ( 32 ) remains for the flow of the cooling medium. Exhaust gas cooler according to one of the preceding claims, characterized in that in the heat exchanger at least one guide plate ( 38 ) is provided. Exhaust gas cooler according to one of the preceding claims, further comprising a collector ( 28 ) downstream of the heat exchanger, which is substantially coincident with the distributor ( 16 ) is designed. Exhaust gas cooler according to one of the preceding claims, characterized in that the limited space ( 34 ) of a distribution jacket ( 18 ), which is essentially identical to a collector shell ( 40 ), which is a collector-side limited space around the collector ( 28 ) surrounds. 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 distribution jacket ( 18 ) and / or the collector coat ( 40 ) and / or the parallel tubes and / or a downstream flange and / or at least one plate ( 20 . 26 . 42 ) are made of aluminum or an aluminum alloy. Exhaust 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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