EP2048345A2 - Heat exchanger, in particular for cooling exhaust gas - Google Patents

Abstract

The exchanger (1) has flow channels (2, 3) for flowing through with respective fluids. The flow channels are separated from each other by a separator (4) e.g. partition wall and/or partition wall section. A housing element (5) feeds the channels with one fluid. A leakage minimization expansion duct (6) is formed in sections between the separator and the housing element such that a leakage flow of the fluid is reduced between the channels, and longitudinal and/or transverse extensions of the separator and the housing element are held by the duct.

Description

The present invention relates to a heat exchanger, in particular for exhaust gas cooling, for an internal combustion engine of a motor vehicle with at least a first flow channel for flow through with a first fluid for cooling a second fluid, with at least one second flow channel for flow through the first fluid and at least one third flow channel to Flow through the first fluid, wherein the at least one second flow channel and the at least one third flow channel are separated by at least one separating element and at least one housing element for flow of the second flow channel and / or the third flow channel with the second fluid.

In internal combustion engines, such as diesel engines, exhaust gas is returned to the engine again to reduce emissions. In this case, a part of the combustion exhaust gas is removed behind the engine and fed back to the unburned air. This recirculated exhaust gas flow is cooled in a heat exchanger such as in an exhaust gas cooler. In this case, the lowest possible mixing temperatures between charge air and the recirculated exhaust gas should be achieved. The low mixing temperatures are required for a fuel-efficient and low-emission combustion process.

For example, during the cold start of the internal combustion engine, the cooling of the recirculated exhaust gas flow is a desired warm-up of the engine but contrary. In this case, the exhaust gas is to be mixed substantially uncooled the charge air to accelerate the heating of the engine. In internal combustion engines for passenger cars and / or for commercial vehicles, it is known that in the heat exchanger for exhaust gas cooling at least one path, in particular a bypass channel is provided, in which the exhaust gas is not cooled, but the cooling section is passed around. The exhaust gas is returned to the engine through the cooled and / or uncooled flow channel. For the control or regulation of the exhaust gas flow, a bypass valve or a bypass flap is required for this purpose.

The heat exchanger, in particular for exhaust gas cooling, can be designed, for example, as a U-flow heat exchanger. In this case, the inlet side and the outlet side are substantially identical in the heat exchanger. The exhaust gas in the device is passed substantially longitudinally along the first flow path through the radiator, is then deflected at the end and returned again substantially in the opposite direction to the entry point. The control device, in particular the bypass valve or the bypass flap, is arranged substantially on the inlet side.

Furthermore, a so-called I-flow arrangement of the heat exchanger for exhaust gas cooling is known. In this case, the flow channel for cooling the exhaust gas and the flow channel, arranged for the uncooled exhaust gas substantially parallel to each other. The exhaust gas enters the radiator on one side and exits the radiator on the other side.

The housing element, in which the control device, in particular the bypass flap or the bypass valve, are arranged, and the partition wall between adjacent flow channels have a gap. Due to manufacturing tolerances and to compensate for the thermal expansion of the components, the gap is known from the prior art. However, the gap leads to leaks, so that there is a leakage flow between the channels.

The object of the invention is to eliminate the disadvantages of the prior art, in particular to avoid an overflow of medium from one to the other channel, in particular to reduce at least significantly.

The object of the invention is solved by the features of claim 1.

The heat exchanger for exhaust gas cooling for an internal combustion engine of a motor vehicle has at least in sections between a separating element and a housing element at least one channel which is designed as Leckageminimierungsdehnungskanal such that the leakage current of the second fluid between the at least one second and the at least one third flow channel minimized and longitudinal - And / or transverse expansions of the separating element and / or the housing member are receivable by the channel.

The separating element is in particular a partition wall or a partition wall section.

Under "housing element" is in particular an inlet or outlet diffuser or a flange to understand.

In an advantageous development, second flow channels and / or at least one third flow channel are formed as tubes, which are accommodated in at least one tubesheet.

In an advantageous development of the invention, at least one housing element has at least one first partition wall section.

In a further advantageous development of the invention, the at least one first partition wall section has a first, in particular groove-shaped recess.

In an advantageous development of the invention, at least one second partition wall section is provided.

In a further advantageous embodiment, the first partition wall section and the second partition wall section engage in each other at least in sections.

In this way, a leakage flow between the second flow channels and at least one third flow channel is particularly advantageously minimized.

In an advantageous development of the invention, the second partition wall section has a second, in particular groove-shaped, recess.

In an advantageous development of the invention, the at least one first partition wall section and / or the at least one second partition wall section are formed substantially s-shaped.

In an advantageous embodiment of the invention, the second partition wall portion is integrally connected to the separating element.

In an advantageous embodiment of the invention, the separating element is at least partially formed as a second partition wall section.

In an advantageous development of the invention, the at least one third flow channel is designed as a bypass channel for avoiding the heat exchanger between the second medium and the first medium.

In this way, it is particularly advantageous for second medium, for example exhaust gas, to flow uncooled through the heat exchanger.

In an advantageous development, it is provided that at least one control element for bypass and / or exhaust gas recirculation control is arranged adjacent, in particular on the upstream side, of the first partition wall section. In this way, exhaust gas can be cooled by the heat exchanger and / or flow uncooled.

In an advantageous embodiment of the invention, the heat exchanger is designed as an I-flow heat exchanger. It is in a particularly advantageous manner on the one hand, the entry into the heat exchanger and on the other substantially opposite side of the outlet of the heat exchanger.

In another embodiment of the invention, the heat exchanger is designed as a U-flow heat exchanger. In this way, a bottom can be saved particularly advantageously and the inlet and the outlet can be arranged in the heat exchanger on the same side.

Further advantageous embodiments of the invention will become apparent from the dependent claims and from the drawing. The subject matters of the dependent claims relate to the heat exchanger according to the invention, in particular for exhaust gas cooling for an internal combustion engine.

Figur 1a:

einen Abgaswärmetauscher im I-Flow mit einem Kanal, der als Leckageminimierungsdehnungskanal ausgebildet ist;

Figur 1b:

einen Abgaswärmetauscher im U-Flow mit einem Leckageminimierungsdehnungskanal;

Fibur 2a:

einen Ausschnitt des Abgaswärmetauschers der Figuren 1 a oder 1b;

Figur 2b:

eine Vergrößerung des Ausschnitts der Figur 2a mit Darstellung der Wärmedehnung des zweiten Trennwandabschnitts;

Figur 3:

ein zweites Ausführungsbeispiel des Leckageminimierungsdehnungskanals;

Figur 4:

ein drittes Ausführungsbeispiel des Leckageminimierungsdehnungskanals.

Embodiments of the invention are illustrated in the drawings and will be explained in more detail below, with a limitation of the invention is not intended to take place. Show it

FIG. 1a

an exhaust gas heat exchanger in the I-flow with a channel, which is designed as a leakage minimization expansion channel;

FIG. 1b

an exhaust gas heat exchanger in the U-flow with a leakage minimization expansion duct;

Fibur 2a:

a section of the exhaust gas heat exchanger of FIGS. 1 a or 1b;

FIG. 2b:

an enlargement of the section of the FIG. 2a showing the thermal expansion of the second partition wall section;

FIG. 3:

a second embodiment of the leakage minimization expansion channel;

FIG. 4:

A third embodiment of the leakage minimization expansion channel.

FIG. 1a shows an exhaust gas heat exchanger 1 in the I-flow with a leakage minimization expansion channel. 6

The heat exchanger 1 is referred to below as the exhaust gas heat exchanger 1. Furthermore, in other embodiments, the heat exchanger 1 may be a coolant radiator for engine cooling and / or a charge air cooler for intercooling and / or an oil cooler for oil cooling such as for transmission oil cooling and / or a condenser of an air conditioner or a gas cooler of an air conditioner or a battery cooler for cooling of batteries.

The exhaust gas heat exchanger 1 has an unspecified designated housing. The housing has at least one housing wall 13 and two housing elements 5. The housing elements 5 are designed, for example, as flange housing elements or inlet and / or outlet diffusers. The housing member 5 is cooled in another embodiment, not shown.

The exhaust gas heat exchanger 1 further has two tube sheets 11 which serve to receive the first flow channels 2, in particular the tubes 7 and / or the at least one third flow channel 3, in particular of the tube 7. The tubes 7 are materially connected to the tubesheets 11 such as by welding, soldering, gluing, etc. and / or positively connected such as by folding, crimping or crimping.

The tubesheets 11 have openings for receiving the second flow channels 2 and the at least one third flow channel, in particular of the tubes.

The second flow channels 2, in particular the tubes 7, have turbulence-generating elements such as winglets or other forms with any shape, which are introduced directly into the tubes 7. In another embodiment, the turbulence-generating elements are inserted into the tubes 7 by means of, for example, turbulence-generating plates.

The housing element 5 and / or the tubesheets 11 are formed from a material, in particular from a sheet material, such as stainless steel or gray cast iron, or from aluminum or from another metal casting. The housing wall 13 is formed for example of a metal such as stainless steel or of another steel or plastic or fiber composite material. Between the second flow channels 2 and the at least one third flow channel 3, a separating element, in particular a partition, is arranged with a second partition wall section 9.

In another embodiment, the exhaust gas heat exchanger 1 has at least one diffuser, in particular an inlet and / or outlet diffuser. Furthermore, a housing is provided for receiving the first flow channels 2, which are each formed between two adjacent disks and / or the at least one third flow channel 3, which is formed between two adjacent disks. The discs are the at least one diffuser and / or to the housing cohesively such as by welding, soldering, gluing, etc. and / or positively connected, such as by folding, crimping or crimping.

The second flow channels 2, which are formed between two adjacent disks, have turbulence-generating elements, such as, for example, turbulence inserts and / or turbulence-generating elements, which are formed, for example, from the disks or other forms of any shape. In another embodiment, the turbulence-generating elements are arranged by means of, for example, turbulence-generating plates between the discs.

The housing element 5 and / or the diffusers are made of a material, in particular of a sheet metal material, such as stainless steel or made of cast iron or of aluminum or of another metal casting. The housing wall 13 is formed for example of a metal such as stainless steel or of another steel or plastic or fiber composite material. Between the second flow channels 2 and the at least one third flow channel 3, a separating element, in particular a partition, is arranged with a second partition wall section 9.

The housing element 5 has a first partition wall section 8. The first partition wall section 8 has a first recess 21, which is formed, for example, as a groove such as a rectangular groove. In another embodiment, the first recess 21 has a substantially triangular or polygonal or trapezoidal and / or at least partially radius or elliptical cross-sectional area.

The second partition wall section is arranged at least in sections in the first recess 21. The width of the first recess 21 is greater than the width of the second partition wall section. In the illustrated embodiment, the second partition wall portion is arranged substantially parallel to the first recess 21. In another embodiment, the second partition wall portion 9 is substantially at an angle of 0 ° to 90 °, in particular from 0 ° to 70 °, in particular from 0 ° to 45 °, in particular from 0 ° to 30 °, in particular from 0 ° to 15 °, in particular from 0 ° to 5 °. Adjacent to the first partition wall section 8, a control element 12, in particular a bypass flap or a bypass valve is arranged. The control element 12 assumes a first bypass position BS, in which the entire inflowing exhaust gas which flows into the heat exchanger 1 via the heat exchanger inlet 15 is directed in the direction of the bypass direction BR into the third flow channel 3 and flows through it. In a second position of the control element 12, which is shown in dashed lines KS flows in the direction KR through the second flow channels 2, in particular the tubes 7. In this position, the exhaust gas is cooled in the tubes 7. In a further third position, the control element 12 assumes a position between the bypass position BS and the radiator position KS. In In this position, exhaust gas flows both through the second flow channels 2 and through the at least one third flow channel 3.

The channel 6 is designed in particular as a labyrinthine sealing and expansion channel. Thus, the thermal expansion of the first separating element 4 and / or the first partition wall section 8 can be absorbed by the channel and a leakage flow from the first space section 23 to the second space section 24 and from the second space section 24 to the first space section 23 can be minimized. The exhaust gas flows through the bypass channel 10 and the tubes 7 in the direction of the exhaust gas flow direction ASR.

FIG. 1b shows the exhaust gas heat exchanger 18 in U-flow with the leakage minimization stretch channel 6. The same features are provided with the same reference numerals as in the previous figures.

In contrast to FIG. 1a rejects the FIG. 1b only one tube bottom 11. Furthermore, the third flow channels are not formed as a bypass channel. The housing element 5 has the heat exchanger outlet 16. The bypass channel is arranged and formed in the housing element 5. The exhaust gas flows in the position KS in the second flow channels, flows through them, is deflected in the deflection element 14 and flows through the third flow channels back toward the heat exchanger outlet 16th

In another embodiment, only a diffuser is provided, and a housing member 5 for receiving the discs. Furthermore, the third flow channels are not formed as a bypass channel. The housing element 5 has the heat exchanger outlet 16. The bypass channel is arranged and formed in the housing element 5. The exhaust gas flows in the position KS in the second flow channels, which are formed between adjacent disks, flows through them, is deflected in the deflecting element 14 and flows through the third flow channels, which are formed between adjacent disks, back toward the heat exchanger outlet 16th

FIG. 2a shows a section of the exhaust gas heat exchanger 1. The same features are provided with the same reference numerals. The enlargement of the FIG. 2a is in FIG. 2b and shows a deformed due to thermal expansion second partition wall portion 19th

The first recess 21 absorbs this thermal expansion or deformation, which can take place as transverse and / or longitudinal expansion.

FIG. 3 shows a second embodiment of the Leckageminimierungsentehnungskanals 6. Here, the partition member 4 and in particular the second partition wall portion 9 is formed substantially S-shaped such that the second partition wall portion 9 forms a second recess 22 into which the first partition wall portion 8 engages at least in sections. In this way, the leakage minimization expansion passage 6 is formed.

FIG. 4 shows a further third embodiment of the leakage minimization stretch channel 6. The same features are provided with the same reference numerals as in the previous figures.

In this case, the second partition wall section 9 is integrally attached to the separating element 4, for example, welded, soldered or glued and / or form-fitting, for example riveted or screwed.

The features of the various embodiments can be combined with each other. The invention can also be used for other than the areas shown.

Claims (15)

Heat exchanger, in particular for exhaust gas cooling, for an internal combustion engine of a motor vehicle
including
at least a first flow channel (1) for flowing through with a first fluid for cooling a second fluid,
at least one second flow channel (2) for flowing through the second fluid and at least one third flow channel (3) for flowing through the second fluid, wherein the at least one second flow channel (2) and the at least one third flow channel (3) through at least one separating element (4) are separated from each other,
at least one housing element (5) for the flow of the second flow channel (2) and / or the third flow channel (3) with a second fluid.
characterized in that
at least in sections, between the separating element (4) and the at least one housing element (5), at least one channel (6) is designed as a leakage minimizing expansion channel (6) such that the leakage flow of second fluid between the at least one second and the at least one third flow channel (6) 2, 3) minimized and longitudinal and / or transverse strains of the separating element (4) and / or the housing element (5) of the channel (6) are receivable. Heat exchanger according to claim 1, characterized in that second flow channels (2) and / or at least one third flow channel (3) are formed between adjacent disks. Heat exchanger according to claim 1, characterized in that second flow channels (2) and / or at least one third flow channel (3) as tubes (7) are formed, which are accommodated in at least one tube plate (11). Heat exchanger according to one of the preceding claims, characterized in that the at least one housing element (5) has at least one first partition wall section (8). Heat exchanger according to claim 4, characterized in that the at least one first partition wall section (8) has a first, in particular groove-shaped, recess (21). Heat exchanger according to one of the preceding claims, characterized in that at least one second partition wall portion (9) is provided. Heat exchanger according to claim 6, characterized in that the first partition wall section (8) and the second partition wall section (9) at least partially intermesh. Heat exchanger according to claim 6 or 7, characterized in that the second partition wall section (9) has a second, in particular groove-shaped, recess (22). Heat exchanger according to one of claims 6 to 8, characterized in that the at least one first partition wall portion (8) and / or the at least one second partition wall portion (9) are formed substantially s-shaped. Heat exchanger according to one of claims 6 to 9, characterized in that the second partition wall portion (9) is integrally connected to the separating element (4). Heat exchanger according to one of claims 6 to 10, characterized in that the separating element (4) is at least partially formed as a second partition wall portion (9). Heat exchanger according to one of the preceding claims, characterized in that the at least one third flow channel (3) as a bypass channel (10) to avoid the heat exchange between the second medium and the first medium is formed. Heat exchanger according to one of claims 4 to 12, characterized in that adjacent, in particular upstream side or downstream, of the first partition wall portion (8) at least one control element (12) for bypass and / or exhaust gas recirculation control is arranged. Heat exchanger according to one of the preceding claims, characterized in that the heat exchanger (1) is designed as an I-flow heat exchanger. Heat exchanger according to one of claims 1 to 14, characterized in that the heat exchanger (18) is designed as a U-flow heat exchanger.

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