DE102005006055B4 - heat exchangers - Google Patents

Abstract

Heat exchanger for heat exchange between two media with an outer heat jacket (1) and an inner heat jacket (2) arranged therein, wherein between the outer (1) and inner (2) heat jacket a first volume (3) for receiving and flowing through a first medium is formed and within the inner heat jacket (2) a second volume (4) for receiving and flowing through a second medium is formed, wherein the inner heat jacket (2) in the form of at least two pocket-shaped, mutually separate and mutually parallel chambers (6) for the second volume (4) which projects into the first volume (3), the second volume (4) being divided by a partition wall (5) extending over part of the length of each chamber (2) into two interconnected volume areas (Fig. 4a, 4b) is divided, so that they are flowed through in opposite directions with the second medium, and wherein the partition wall (5) through the entire width of the second vol (4) of the inner heat jacket (2) pulls.

Description

The invention relates to a heat exchanger, in particular an exhaust gas heat exchanger for a water-cooled internal combustion engine.

Internal combustion engines must increasingly meet stricter emission limits. These limit values can be achieved in terms of fuel efficiency if the exhaust gas recirculation (EGR) known in practice additionally receives cooling via an exhaust gas heat exchanger. By adding and cooling non-combustible exhaust gas components for cylinder filling, the combustion temperature and thus the NO _x content of the exhaust gas is reduced. During exhaust gas recirculation, part of the burned exhaust gas is taken from the exhaust manifold and returned to the intake manifold via a pipeline. There, the burned exhaust gas is supplied to the intake mixture.

State of the art

Heat exchangers for cooling exhaust gas recirculation gases (EGR) in internal combustion engines are known from the prior art. These can be made of stainless steel by welding or brazing or cast light metal in the sand casting, die-casting or lost foam process. The former heat exchangers are relatively expensive. The heat exchangers produced in the sand casting or lost foam process are also more expensive than those produced by the die casting process. Moreover, from a process engineering point of view, these are more critical with regard to residual dirt.

From the DE 20 2004 003 131 U1 For example, an exhaust gas heat exchanger for a water-cooled internal combustion engine is known. The heat exchanger consists of at least two or more main parts made of cast aluminum, which are put together cup-shaped and thus form the exhaust and water-side cavities for the heat exchange through the part walls with associated inlets and outlets for exhaust or cooling water. These are screwed together, clamped or glued by mutually mating flanges, which form a flange, into a unit. In the DE 36 33 236 C2 is disclosed in detail a heat exchanger in a heater for small rooms, which shows an enlargement of the exchanger surface and multiple deflections by corrugated side walls and partitions. In the DE 76 13 603 U the cross-sections of each gas and water-bearing areas by partition walls are coordinated so that increases the cross-section of the water area while it is smaller in the gas area. This complies with the different volumes of water or gas in the heat exchange process and enables a uniform heat exchange.

task

The invention is based on the technical problem of providing a heat exchanger of the type mentioned, which enables a performance increase in a cost effective manner and which also can be produced in the die casting process.

The invention solves this problem by providing a heat exchanger with the features of claim 1. For this purpose, a heat exchanger for heat exchange between two media is provided with an outer heat jacket and an inner heat jacket disposed therein, wherein between the outer and inner heat jacket a first volume for receiving and Flow through a first medium is formed and within the inner heat jacket, a second volume for receiving and flowing through a second medium is formed, wherein the second volume is divided by a not extending over the entire length of the second volume dividing wall into two interconnected volume areas such that these are flowed through in opposite directions with the second medium. According to the invention, a part of the inner heat jacket is shaped such that the second volume in the form of at least two pocket-shaped chambers arranged parallel to one another projects into the first volume.

Advantageously, the inner heat jacket is shaped such that the pocket-shaped formations are formed as individual, separate chambers.

In a further development of the invention according to claim 2, the partition wall is comb-like and comprises at least two prongs, wherein each of the teeth of the comb protrudes into each one of the chambers and thus divides each chamber into the respective volume areas.

In an advantageous development of the invention according to claim 3, the inner heat jacket is shaped such that each two adjacent chambers of the second volume are connected to each other via an acute-angled narrowing of the second volume.

In a further development of the invention according to claim 4, the partition is held in the constriction or the constrictions.

According to a development of the invention according to claim 5 are on the inner wall of the acute-angled constriction of the inner heat jacket contact points in the form of grooves for receiving and holding the partition provided so that the partition comes into contact with the inner heat jacket at these contact points.

In an advantageous embodiment of the invention according to claim 6, the farthest in the acute-angled constriction end of the partition wall is bent and jammed in the acute-angled constriction.

In a preferred embodiment of the invention according to claim 7, the partition wall within the acute-angled constriction on a curved surface which comes in at least two points with the inside of the acute-angled constriction in touch.

In a particularly preferred embodiment of the invention according to claim 8, the first volume between the outer and the inner heat jacket by means of a common sealing surface is lockable.

In an advantageous development of the invention according to claim 9, the second volume between the inner heat jacket and a flange final lid is lockable.

According to a further developed according to claim 10 heat exchanger, the outer heat jacket on at least one inlet and at least one outlet opening for the first medium.

In an alternative development of the invention according to claim 11, the lid closing off the flange has at least one inlet opening and at least one outlet opening for the second medium.

According to a development of the invention according to claim 12, the heat jackets, the lid and / or the partition of the heat exchanger in the die-casting process can be produced.

According to a further developed according to claim 13 heat exchanger, the inner and outer heat jacket, the cover and the partition independently of one another selectively metal, sheet metal and / or plastic.

According to a further advantageous embodiment of the invention according to claim 14, the heat exchanger is designed as an exhaust gas heat exchanger of a liquid-cooled internal combustion engine.

In this, according to claim 15, the first medium is a liquid coolant and the second medium is the exhaust gas of this internal combustion engine.

Further features, advantages and advantageous embodiments of the invention will become apparent from the dependent claims, as well as from the following description of the invention with reference to the accompanying drawings. In the following, the invention will be explained by way of example on an exhaust gas heat exchanger, the explanations being analogous to a general heat exchanger transferable. In a very simplified schematic way:

1 a longitudinal section through the exhaust gas heat exchanger according to the invention,

2a a longitudinal section through an exhaust passage of the exhaust gas heat exchanger according to the invention, in which the partition is held in a groove,

2 B a longitudinal section through an alternative exhaust passage of the exhaust gas heat exchanger according to the invention, in which the partition wall is bent at the end,

2c a longitudinal section through an alternative exhaust passage of the exhaust gas heat exchanger according to the invention, in which the partition wall is corrugated,

3a a longitudinal section through a coolant passage of the exhaust gas heat exchanger according to the invention, in which the partition wall is held in a groove,

3b a longitudinal section through an alternative coolant channel of the exhaust gas heat exchanger according to the invention, in which the partition wall is bent at the end,

3c a longitudinal section through an alternative coolant channel of the exhaust gas heat exchanger according to the invention, in which the partition wall is corrugated,

4a a view of the flange of the exhaust gas heat exchanger,

4b a cross section through the exhaust gas heat exchanger according to the invention directly behind the flange,

5 a schematic diagram of a flow-through exhaust gas heat exchanger,

6 a schematic diagram of a bypassed exhaust gas heat exchanger.

1 shows a longitudinal section through the heat exchanger according to the invention in the form of an exhaust gas heat exchanger. The exhaust gas heat exchanger has an outer heat jacket 1 and an inner heat jacket disposed therein 2 on. Between outer and inner heat jacket 1 . 2 is a first volume 3 for intake and flow a liquid coolant and within the inner heat jacket 2 a second volume 4 formed for receiving and flowing through the exhaust gas to be cooled, wherein the inner volume 4 by a partition not shown here in two interconnected volume areas 4a and 4b is divided. Both warmers 1 . 2 are by means of a common sealing surface, which is arranged perpendicular to the flow direction, lockable. The sealing surface has a flange 14 on the outer heat jacket 1 and a flange 11 on the inner heat jacket 2 on, wherein the lower flange surface of the inner heat jacket 2 on the upper flange surface of the outer heat jacket 1 to come to rest. The sealing of this flange-like connection against the environment, which is the first volume 3 includes for receiving and flowing through a liquid coolant, by means of sheet metal bead (s) 13 ' , Elastomeric seal 13 , Gluing, jamming and / or screwing. Furthermore, the exhaust gas heat exchanger with its the bottom or the rear wall 1'' the outer heat jacket 1 connectable to a flange of the exhaust gas recirculation line (not shown) such that they extend in the first and second volumes 3 . 4 located media, coolant and exhaust gas, are sealed to the environment that there may be no unwanted leakage or mixing of the two media. The two volumes 3 . 4 will be referred to as exhaust gas 4 and coolant channels 3 designated. In the 1 embodiment shown has three substantially parallel to each other, pocket-shaped exhaust gas channels 4 on. However, there are embodiments with a different number of pockets 6 possible.

The inner and outer heat jacket 1 . 2 , the lid and the partition 5 can independently of one another optionally contain metal, sheet metal and / or plastic. The exhaust gas heat exchanger can thus be represented in a hybrid construction. Preferably, the exhaust gas heat exchanger is produced by die casting and thus enables a process-technically safe and cost-effective design with regard to residual dirt. However, an embodiment of the heat exchanger in stainless steel or light metal, which was produced by means of sand casting, lost foam method or sheet metal deep-drawing process, is also possible.

Furthermore, the exhaust gas 4 and coolant channels 3 acting volumes to increase the heat transfer surface carried out advantageously bag-like.

It is also advantageous that the draft of the exhaust and coolant side can be similar, so that the principle of constant wall thickness can be implemented. The minimum material thickness during casting is preferably ≥ 3 mm. The efficiency of the exhaust gas heat exchanger can be favorably increased by increasing the number, length and height of the pockets 6 varied or fixed.

This is advantageously between the middle of the three pocket-shaped exhaust gas channels shown 4 and the back wall 1'' the outer heat jacket 1 a seal 7 provided, which ensures that the coolant as large an inner area of the inner heat jacket 2 flows around and the immediate flow of coolant between the inlet and outlet ports (not shown separately) is hindered. This ensures a high heat exchange between the exhaust gas and the coolant.

For the sake of clarity, the same reference numbers will be used hereinafter for functionally identical or equivalent components, in so far as the above description also applies 1 directed.

2a shows a longitudinal section through an exhaust passage of the exhaust gas heat exchanger according to the invention along the in 1 shown dashed line A. The internal volume 4 is through a partition 5 in two volume ranges 4a . 4b divided. It is important that the partition does not reach the back wall 2 '' of the inner heat jacket 2 goes through, so that the two resulting volume areas 4a . 4b are still connected. Through the partition 5 is the exhaust gas, which in a first volume range 4a the exhaust duct flows in, forced to the partition wall 5 flow around in another volume area 4b , The arrows symbolize the flow direction of the exhaust gas. The exhaust gas flows over the further volume range 4b in the not shown EGR return line.

3a shows a longitudinal section through a coolant channel 3 of the heat exchanger according to the invention along the in 1 shown dashed line B. This section extends between two adjacent pocket-shaped exhaust ducts 4 and essentially shows the course of the coolant channel 3 , The inner heat jacket 2 is opposite at this point 2a formed inwardly and consists primarily of an acute angled wall assembly, the exhaust gas volume 4 at this point severely narrows, while the cooling water volume 3 here is greatly expanded. This narrowing 4 ' connects two adjacent exhaust ducts 4 with each other and has at its acute-angled end a groove 12 for receiving and holding the partition 5 on. In 3a is also an inlet port 9 for the coolant shown. Instead of the groove 12 can the partition 5 also at her furthest in the constriction 4 ' protruding end bent or folded and in the narrowing 4 ' be stuck, like in 3b shown. Another alternative to mounting the partition 5 in the narrowing 4 ' is in 3c shown; Here, the partition wall is wave-shaped and can at least two points with the inner heat jacket 2 on the inside of the narrowing 4 ' come into contact and thus in the constriction 4 ' be fixed, and here too the farthest into the narrowing 4 ' protruding end of the partition 5 bent over or in a groove 12 can be held. The bent or corrugated version of the partition 5 is also in 2 B respectively. 2c shown. Furthermore, from the synopsis of 1 . 2a -C and 3a -C can be seen that the partition 5 through the entire second volume 4 of the inner heat jacket 2 pulls and thus all in 1 shown pocket-shaped exhaust channels 4 in a respective upper and lower volume range 4a . 4b divided.

This is also evident in 4a and 4b to recognize. 4b shows a cross section through the exhaust gas heat exchanger according to the invention directly behind the flange 11 (as in 4a shown). In the outer heat jacket 1 is the inner heat jacket 2 whose folded structure is the pocket-shaped exhaust gas channels 4 forms. The partition 5 divides each of the exhaust channels into an upper and a lower volume range 4a . 4b , The dashed lines A and B correspond to the same lines in FIG 1 and show the location of in 2a and 3a shown cutting planes. 4b also shows a possible arrangement of the coolant inlet and outlet openings 9 respectively. 10 , However, these openings can also bottom, top, side or in the flange 11 be integrated. Furthermore, here again the seal 7 between the middle of the shown exhaust ducts 4 the respective volume ranges 4a . 4b and the inner wall 1'' the outer heat jacket 1 to see.

4a shows a view on the flange 11 , made in one piece from the inner heat jacket 2 formed and in the assembled state via the seal, not shown here 13 . 13 ' with the outer heat jacket not separately shown 1 connected and thus the volume 3 the coolant channel (not shown) completes. The flange has not shown inlet and outlet openings for the exhaust gas.

In a further variant of the heat exchanger according to the invention is the inner heat jacket 2 shaped such that the pocket-shaped formations are formed as individual, separate chambers. In this case, a section would be taken along the dashed line B in FIG 1 no rejuvenation 4 ' but a substantially rectilinear course of the inner heat jacket 2 show that together with the outer heat jacket 1 in this area B a continuous first volume 3 forms, which separates the respective adjacent chambers from each other. Here, the partition 5 be comb-like and comprise at least two prongs, each of the teeth of the comb protrudes into each one of the chambers and thus each chamber into the respective volume areas 4a . 4b divided. In this embodiment, the inner heat jacket 2 , similar to in 3b and 3c shown opposite the flange 11 be offset to the interior of the heat exchanger. It is also conceivable, instead of a comb-shaped partition 5 to provide a partition replacing configuration of individual separate partition wall parts, wherein each of these partition wall parts a corresponding chamber in the respective volume areas 4a . 4b divided.

• – den äußeren topfförmigen Wärmemantel 1,
• – den inneren, mehrere Taschen und den Flansch bildenden Wärmemantel 2,
• – die Trennwand 5 und
• – den Deckel.

The exhaust gas heat exchanger according to the invention thus has four separate parts:

• - The outer pot-shaped heat jacket 1 .
• - The inner, several pockets and the flange forming heat jacket 2 .
• - the partition 5 and
• - the lid.

Although the composite heat exchanger has a complex structure, each of the four individual parts is relatively simple in structure and is therefore preferably inexpensive to produce by die-casting.

For the operation of an internal combustion engine, both states with cooled and uncooled exhaust gas recirculation are important.

In 5 the cooled exhaust gas recirculation is shown. The arrows symbolize the flow direction of the exhaust gas. A portion of the burned exhaust gas is taken from the exhaust manifold, not shown, and via an exhaust gas recirculation line 16 to the exhaust gas heat exchanger 15 guided, which via a flange-like connection 17 at the exhaust gas recirculation line 16 is appropriate. With open bypass flap 18 The exhaust gas flows through the exhaust gas heat exchanger 15 U-shaped and leaves it in the direction of arrow on the exhaust gas recirculation line 16 towards the intake manifold (not shown separately). There, the burned exhaust gas is supplied to the intake mixture.

In 6 the uncooled exhaust gas recirculation (bypass operation) is shown. The arrows in turn symbolize the flow direction of the exhaust gas. The bypass flap 18 closes in the position shown, the inlet opening of the exhaust gas heat exchanger 15 , The exhaust gas taken from the exhaust manifold is via the exhaust gas recirculation line 16 returned directly to the intake manifold, without the exhaust gas heat exchanger 15 to flow through there to supply the burned uncooled exhaust gas to the intake mixture.

Claims (15)

Heat exchanger for heat exchange between two media with an outer heat jacket ( 1 ) and an inner heat jacket arranged therein ( 2 ), whereby between outer ( 1 ) and inner ( 2 ) Heat jacket a first volume ( 3 ) is designed to receive and flow through a first medium and within the inner heat jacket ( 2 ) a second volume ( 4 ) is designed for receiving and flowing through a second medium, wherein the inner heat jacket ( 2 ) in the form of at least two pocket-shaped, mutually separated and mutually parallel chambers ( 6 ) for the second volume ( 4 ) formed in the first volume ( 3 protrude), wherein the second volume ( 4 ), over part of the length of each chamber ( 6 ) extending partition ( 5 ) into two interconnected volume areas ( 4a . 4b ) is divided, so that they are flowed through in opposite directions with the second medium, and wherein the partition wall ( 5 ) through the entire width of the second volume ( 4 ) of the inner heat jacket ( 2 ) pulls. Heat exchanger according to claim 1, characterized in that the partition ( 5 ) is comb-like and comprises at least two prongs, each of the prongs of the comb in each one of the chambers ( 6 ) and thus each chamber ( 6 ) into the respective volume areas ( 4a . 4b ). Heat exchanger according to claim 1, characterized in that the inner heat jacket ( 2 ) is shaped such that in each case two adjacent formations of the second volume ( 4 ) via an acute-angled narrowing ( 4 ' ) of the second volume ( 4 ) are interconnected. Heat exchanger according to claim 3, characterized in that the partition wall ( 5 ) in the narrowing or constrictions ( 4 ' ) is held. Heat exchanger according to claim 4, characterized in that on the inner wall of the acute-angled constrictions ( 4 ' ) of the inner heat jacket ( 2 ) Contact points ( 8th ) in the form of grooves ( 12 ) for receiving and holding the partition ( 5 ) are provided so that the partition ( 5 ) at these contact points ( 8th ) with the inner heat jacket ( 2 ) comes into contact. Heat exchanger according to claim 4, characterized in that the furthest in the acute-angled constriction ( 4 ' ) projecting end of the partition ( 5 ) bent in the acute-angled constriction ( 4 ' ) is jammed. Heat exchanger according to claim 4, characterized in that the partition ( 5 ) within the acute-angled narrowing ( 4 ' ) has a curved surface which at at least two points with the inside of the acute-angled constriction ( 4 ' ) comes into contact. Heat exchanger according to one of the preceding claims, characterized in that the first volume ( 3 ) between the outer ( 1 ) and the inner ( 2 ) Heat jacket by means of a common sealing surface is lockable. Heat exchanger according to one of the preceding claims, characterized in that the second volume ( 4 ) between the inner heat jacket ( 2 ) and a flange ( 11 ) final lid is lockable. Heat exchanger according to one of the preceding claims, characterized in that the outer heat jacket ( 1 ) at least one inlet ( 9 ) and at least one outlet opening ( 10 ) for the first medium. Heat exchanger according to claim 9 or 10, characterized in that the flange ( 11 ) closing lid has at least one inlet opening and at least one outlet opening for the second medium. Heat exchanger according to one of the preceding claims, characterized in that the heat jackets ( 1 . 2 ), the lid and / or the partition ( 5 ) of the exhaust gas heat exchanger in the die-casting process can be produced. Heat exchanger according to one of claims 1 to 11, characterized in that the inner and outer heat jacket ( 1 . 2 ), the lid and the partition ( 5 ) independently of one another optionally contain metal, sheet metal and / or plastic. Heat exchanger according to one of the preceding claims, characterized in that the heat exchanger is designed as an exhaust gas heat exchanger of a liquid-cooled internal combustion engine. Heat exchanger according to claim 14, characterized in that the first medium is a liquid coolant and the second medium is the exhaust gas of the internal combustion engine.

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