DE102011056153B4 - Impact surface heat exchanger for arrangement in an exhaust system of a motor vehicle - Google Patents

Abstract

Heat exchanger (1) for arrangement in an exhaust system of a motor vehicle, wherein the heat exchanger (1) heat transfer of exhaust gas contained in an exhaust gas (9) to a cooling medium (6), wherein the exhaust gas (9) through a heating channel (2) and the cooling medium (6) flow through a cooling channel (3), characterized in that the heating channel (2) is subdivided into a feed chamber (7) and a discharge chamber (8), wherein the discharge chamber (8) is arranged on a heat exchanger wall (4) is and the heat exchanger wall (4) directly adjacent to the cooling channel (3) and the feed chamber (7) on the heat exchanger wall (4) opposite side of the discharge chamber (8) is arranged and wherein the discharge chamber (8) and the feed chamber (7 ) are at least partially parallel, wherein between the feed chamber (7) and the discharge chamber (8) openings (13) are arranged through which the exhaust gas (9) from the feed chamber (7) flows into the discharge chamber (8) and in the discharge chamber (8) substantially perpendicular to the heat exchanger wall (4) meets and / or bounces and then through the discharge chamber (8) can be discharged.

Description

The present invention relates to a heat exchanger for arrangement in an exhaust system of a motor vehicle according to the features in the preamble of patent claim 1.

In today's automotive industry, internal combustion engines are still provided as the main drive source. Here are two different combustion concepts significantly in use, on the one hand, the spark ignition gasoline engine, on the other hand, the self-ignited diesel engine. The internal combustion engines convert the chemical energy contained in a fuel into mechanical energy for propulsion as well as into thermal energy, which is generated during the combustion process and is dissipated via the engine and the exhaust gas. The combustion engines are limited by the idealized Carnot process in the conversion efficiency of the chemical energy into mechanical energy. Since about 40% of this is converted into mechanical energy, about 60% of the chemical energy contained in the fuel is dissipated as a loss.

In recent years, therefore, there have been various efforts to recover the heat energy contained in the exhaust gas accordingly and thereby further increase the efficiency of the combustion process with respect to the use of the energy in the motor vehicle. As a result, the consumption and the CO2 emissions of a particular motor vehicle is lowered.

For this purpose, various concepts for using the energy contained in the exhaust gas are known from the prior art. For example, it is possible by charging machines, in particular in the form of exhaust gas turbochargers, to further increase the efficiency of an internal combustion engine. It is also known to arrange thermoelectric generator units in the region of the exhaust line in order to convert with the help of the Seebeck effect the heat energy contained in the exhaust gas into electrical energy and to supply the motor vehicle electrical system or other consumers.

For example, is from the EP 1 679 480 A1 known to arrange thermoelectric generator units for generating electrical energy in a motor vehicle, being used as the heat source of the exhaust system and as a heat sink of the cooling water circuit of the motor vehicle. On the control options both in the exhaust system, as well as in the cooling water circuit, it is also possible to set the operating point of the thermoelectric generator units in each case so that they work as far as possible with an optimum.

Furthermore, the shows DE 31 03 197 A1 a heat exchanger for the operation of exhaust gases of piston engines, in particular for the heating of motor vehicles. In this heat exchanger, a fluid passage for the exhaust gas is used, wherein downstream of the inlet of this fluid channel, a baffle device is provided in the form of a nozzle arrangement whose nozzles guide the exhaust gas along the heat exchanger surface. Also the DE 10 2009 013 535 A1 shows a thermoelectric device for generating electrical energy from heat. This is characterized in particular by the fact that it is made possible in the interior of the device by a corresponding holding structure, to allow the flow through a hot and a cold medium over the largest possible thermal contact and thus to ensure a maximum heat transfer. The DE 10 2009 038 643 A1 further shows a heat exchanger, which consists of a plurality of tubes and thus makes it possible to deliver the heat of the exhaust gas to a supplied cooling water.

A problem that arises in the arrangement of thermoelectric generators on or in an exhaust system is the efficiency of the heat transfer in longitudinally, transversely or kreuzangeströmten generator units. In particular, for the generation of high electrical energy flow rates, the required amounts of heat in the transient operation of the internal combustion engine in a motor vehicle can not always be provided beyond doubt.

Object of the present invention is therefore, starting from the prior art, to provide a heat exchanger for arrangement in an exhaust system of a motor vehicle, which extracts from the prior art known arrangements the exhaust gas a higher amount of heat.

The aforementioned object is achieved with a heat exchanger for arrangement in an exhaust system of a motor vehicle according to the features in claim 1.

Advantageous embodiments of the present invention are part of the dependent claims.

The heat exchanger according to the invention for arrangement in an exhaust system of a motor vehicle, wherein the heat exchanger allows heat transfer of the exhaust gas heat contained in an exhaust gas to a cooling medium, wherein the exhaust gas flow through a heating channel and the cooling medium through a cooling channel, characterized in that the heating channel in a Feed chamber and a discharge chamber is broken down, wherein the discharge chamber to a heat exchanger wall is arranged and the heat exchanger wall is directly adjacent to the cooling channel and the feed chamber is disposed on the heat exchanger wall opposite side of the discharge chamber and wherein the discharge chamber and the supply chamber at least partially parallel, wherein between the supply chamber and the discharge chamber openings are arranged through which the Exhaust gas from the supply chamber flows into the discharge chamber and in the discharge chamber substantially perpendicular to the heat exchanger wall and / or bounces and is then discharged through the discharge chamber.

The heat exchanger according to the invention is incorporated in particular in an exhaust system of a motor vehicle. He can do this in the context of the invention, a channel-shaped, a plate-shaped or even a cylindrical structure. It is characteristic that both the feed chamber, and the discharge chamber run parallel at least in sections and thus allow passage of the exhaust gas from the feed chamber into the discharge chamber. The exhaust gas thus passes through the exhaust tract of the internal combustion engine, which is in particular represented by a manifold, and is discharged via the exhaust gas line. The exhaust system usually has various exhaust aftertreatment units, such as catalysts or the like. The heat exchanger according to the invention is arranged in the region of the exhaust line and can in turn be arranged directly on the manifold or after the manifold or in the further course of the exhaust line. The exhaust gas is thus first supplied to the heat exchanger and passes through the heat exchanger in the heating channel. The heating channel of the heat exchanger itself may be elongated in tubular form, so that the heating channel forms part of the exhaust line or else be designed as a plate heat exchanger or in any other geometric shape. Likewise, the heat exchanger according to the invention can also be arranged in a bypass duct of the exhaust line. After flowing through the heating channel, the exhaust gas is discharged through the further exhaust gas line, so that it emerges according to a rear silencer accordingly in the environment.

According to the invention, the heating channel is divided into a feed chamber and a discharge chamber. Within the scope of the invention, the feed chamber and discharge chamber may also have a channel-shaped or other spatially geometrical configuration, for example as a cuboid shape or else as a rectangular shape or else as a cylindrical shape. Also, the supply chamber and discharge chamber may form hybrid forms of the aforementioned geometric embodiments. It is essential that the feed chamber and the discharge chamber extend at least in sections and / or also in sections in parallel.

In addition, openings are provided between the supply chamber and the discharge chamber through which the exhaust gas flows from the supply chamber into the discharge chamber. By virtue of this principle, the exhaust gas backpressure contained in the exhaust gas system or produced by the flow resistance is optimally utilized in order to increase the heat transfer from the exhaust gas to the heat exchanger wall.

In particular, this effect is assisted by the fact that the exhaust gas flowing into the discharge chamber strikes and / or bounces substantially perpendicularly onto the heat exchanger wall and can then be discharged through the discharge chamber. The exhaust gas impinging on the heat exchanger wall impinges on it in the form of free jets and is swirled there. On the heat exchanger wall itself, the exhaust gas is distributed in a star shape or from the point of impact in the circumferential direction. The star-shaped spreading or spreading is to be understood in the context of the invention as a radially symmetric spreading or as radially asymmetric spreading. Thus, in the radially asymmetric spreading in one direction more exhaust gas is spread in a star shape than in another direction. Likewise, in the context of the invention, a star-shaped distribution or spreading is also to be understood as a radially symmetrical, centrally offset spreading. As a result, for example, a limiting wall is achieved earlier, which may have relevance for the cooling performance, as increased temperatures occur on this wall. As a result, a particularly efficient heat transfer from the exhaust gas impinging on the heat exchanger wall to or into the heat exchanger wall, whereby the heat exchanger performance is further increased. The exhaust gas itself uses the resulting during the Gesamtabführvorganges the exhaust gas exhaust backpressure effectively. The introduced into the feed chamber exhaust gas passes through the feed chamber and enters thereby and / or at the end of the feed chamber in the discharge chamber. This is made possible by openings and / or by separating plates between the feed chamber and the discharge chamber. The exhaust gas which has flowed into the discharge chamber through the openings of the dividing wall and / or the perforated plates initially strikes the heat exchanger wall almost at a right angle. The exhaust gas thus bounces against the heat exchanger wall and is distributed in a star shape on the surface of the heat exchanger wall from the impact surface. This results in a particularly efficient heat input from the residual heat contained in the exhaust gas in the heat exchanger wall.

On the opposite side of the heat exchanger wall, a cooling channel is arranged, through which a cooling medium flows. In the simplest embodiment of the current invention can thus the exhaust gas are cooled and / or the cooling medium are heated. For example, this would be conceivable for cooling the exhaust gas, in particular in the exhaust gas recirculation or for faster heating of the cooling circuit, which in turn can then give off heat to, for example, an oil circuit of an internal combustion engine. Likewise, the cooling circuit with the heat extracted from the exhaust gas can be used for heating the vehicle interior.

In a preferred embodiment, at least one thermoelectric generator is arranged on and / or in the heat exchanger wall, which converts the temperature difference by means of the Seebeck effect into electrical energy. Preferably, the cooling channel is connected to the cooling circuit of the internal combustion engine.

In a particularly preferred embodiment, the heat exchanger wall is formed of a separating plate and / or at least partially formed as a thermoelectric generator or thermoelectric generators are at least partially disposed on the heat exchanger wall. In the context of the invention, the heat exchanger wall between the heating channel and the cooling channel can thus be formed by a separating plate, wherein the separating plate is a metal sheet, which has particularly good thermal conductivities. In particular, it is a metallic sheet. Preferably, heat exchanger fins are arranged on the heat exchanger wall in the cooling channel and / or the heating channel, here in particular in the discharge chamber. The heat exchanger fins increase the surface of the heat exchanger wall and thus allow better heat transfer from the respective medium, ie the heating medium and / or the cooling medium in the heat exchanger wall and thus to the respective opposite medium. The heat exchanger wall may be formed in the context of the invention as a curved and / or curved plate, so that increases over this the surface.

Furthermore, thermoelectric generators are particularly preferably coupled to the heat exchanger wall or the heat exchanger wall is designed as a thermoelectric generator. In connection with the heat exchanger according to the invention, it is thus possible always to extract an effective amount of heat from the exhaust gas in order thus to provide and / or maintain a corresponding temperature difference which realizes a constant generation of electrical energy by the Seebeck effect. The thermoelectric generators are preferably arranged on the cold side, that is to say in the region of the cooling channel, that are not in direct contact with the relatively excessively hot exhaust gas. It is thus also avoided that the highly corrosive fractions contained exhaust gas has a detrimental effect on the thermoelectric generator elements. As a result, a heat exchanger is provided which has a long service life with thermoelectric generators integrated therein.

Further preferably, the exhaust gas flowed into the discharge chamber is reflectable on one end side of the discharge chamber. This means in the context of the invention that the exhaust gas first flows into the feed chamber, from the feed chamber via openings in the discharge chamber and impinges on the heat exchanger wall. At one end side of the discharge chamber, the exhaust gas is reflected, so that it is centrally passed through a discharge line which leads from the discharge chamber into the further exhaust gas line. The reflection in turn does not adversely increase the exhaust backpressure so that exhaust gas is correspondingly removed further.

In the context of the invention, inflow regions are preferably provided for further increasing the heat transfer at the heat exchanger wall, wherein an inflow region is characterized in that it delimits an area on the heat exchanger wall itself. Preferably, an inflow region is designed like a shell so that it receives as centrally as possible a free jet coming through the opening from the feed chamber and has a geometry which supports the vortexes propagating in a star shape from the impinging free jet.

Further preferably, a plurality of inflow regions are provided on the heat exchanger wall, wherein preferably an inflow region always opposes an opening between the feed chamber and the discharge chamber. The several inflow regions are in turn arranged on the heat exchanger wall in a checkerboard or honeycomb pattern. This means that an inflow region is correspondingly adjacent to at least one, preferably four or more inflow regions.

To further increase the efficiency of the heat transfer Einströmstutzen are further provided at the openings for targeted flow line, wherein the inflow are oriented in the direction of the inflow. An inflow is thus analogous to an inflow funnel or designed to a diffuser, so that it directs the flow line targeted and / or supported. The inflow nozzle ensures a targeted steering of the exhaust gas jet on the heat exchanger wall and promotes the turbulence propagating from the exhaust gas jet.

Furthermore, at least two openings and / or inflow nozzles and / or are preferred in the flow direction of the feed chamber Inflow areas arranged in succession cascaded. In the context of the invention, this means that a plurality of openings and / or inflow nozzles and / or inflow regions are arranged consecutively or subsequently or else cascaded over the parallel course between the feed chamber and the discharge chamber in the exhaust gas flow direction. Thus, through the opening in the supply chamber, which is first reached by the exhaust gas in the flow direction, a first part of the exhaust gas flows from the supply chamber into the discharge chamber. Through the opening, which is subsequently achieved in the flow direction, that is, as at least second flows according to another part of the exhaust gas into the discharge chamber. This can continue indefinitely, so that 10, 20 or even 50 openings are arranged successively between the feed chamber and the discharge chamber in the exhaust gas flow direction.

In the discharge chamber, this results in an inverse construction, so that the exhaust gas, which first flows in the exhaust gas flow direction from the feed chamber into the discharge chamber, is fed last from the discharge chamber to the further exhaust gas line. Consequently, the structure is to be seen so that the part of the exhaust gas, which is the last transferred from the feed chamber into the discharge chamber, is supplied according to the first further exhaust line.

However, the structure is also conceivable that it is similar to the countercurrent principle, so that the supply to the feed chamber and the discharge from the discharge chamber according to flow in parallel from one side into the heating channel. Accordingly, the part of the exhaust gas flowing through the first opening in the exhaust gas flow direction from the supply chamber into the discharge chamber would also be discharged from the discharge chamber as the first part again. The exhaust gas in the discharge chamber, in particular in the inflow regions, thus flows together and adds up and is accordingly discharged from the discharge chamber into the further exhaust gas line.

Separating webs are preferably arranged between the inflow passages, wherein the dividing webs delimit the inflow regions from one another. The delimitation of the inflow between each other by dividers is a particularly cost-effective alternative, wherein the dividers can be designed geometrically according to the desired turbulence, so that they additionally supportive for an increase in the heat transfer effect. Likewise, an enlargement of the surface of the heat exchanger wall takes place through the separating webs, so that an increased heat transfer is also promoted thereby.

Further particularly preferably, the separating webs are formed in the discharge chamber such that they undercut the inflow supports in the flow direction, so that the inflow nozzles project into the inflow region. This ensures that the exhaust gas flowing through the inflow port into the inflow region swirls correspondingly and then is discharged through the circumferential gap, which arises between the divider webs or the inflow region and the inflow port, in the discharge chamber and does not flow back into the supply chamber.

Further preferably, the thermoelectric generators are coupled with liquid metal to the heat exchanger wall. This results in a particularly good thermal conductivity between the heat exchanger wall and thermoelectric generator. The liquid metal allows the compensation of possible geometric production fluctuations even during the coupling, so that a full-surface system between thermoelectric generator element and heat exchanger wall is given.

In the context of the invention, a pulsed flow is utilized in particular for the purpose of exploiting an optimum impact surface effect for cooling. Pulsed flow allows baffled cooling to increase efficiency by up to 20%. The pulsieirenden impact rays thereby increase the cooling efficiency compared to a stationary comparison configuration.

In particular, in the exhaust gas tract of an internal combustion engine there is a pulsating gas flow. This depends on the one from the respective operating point in which the internal combustion engine is currently located, on the other hand, however, it is also fundamentally dependent on the number of cylinders. For example, a 4-cylinder engine has a different pressure pulsation in the exhaust line than a 6-cylinder engine. Likewise, the pressure pulsation is different from each other by different manifold components even for engines with the same number of cylinders.

In the context of the invention, it therefore makes sense to use the pressure pulsation of the exhaust gas prevailing in the exhaust gas system of a motor vehicle to increase the efficiency of the baffled surface heat exchanger according to the invention. Thus, the baffled heat exchanger is preferably designed for the expected pressure pulsations such that compared to a stationary flow and / or a conventional dimensioning results in a further increase in efficiency and utilization of Druckpulsationseffekts. Significantly, the geometry of the feed chamber and / or discharge chamber of the heat exchanger is designed and / or dimensioned such that they are optimally adapted to a pressure pulsation frequency of the exhaust gas, in particular for an operating point spectrum.

However, the prevailing pressure pulsation is also dependent on the respective operating point of the internal combustion engine. Decisive for this are the factors speed and load. In the context of the invention, it is therefore conceivable to define a main operating point range in which the internal combustion engine is predominantly operated with high or highest probability. In stationary internal combustion engines, for example, the power generation, it is also possible to set an operating point.

Relevant frequencies for pulsating flow are preferably 0 Hz to 200 Hz in 4-cylinder engines in a speed range of about 6,000 U / min. 0 Hz to 300 Hz for 6-cylinder engines, also in a speed range of about 6,000 rpm. Preferably 0 Hz to 400 Hz in 8-cylinder engines at a speed of about 6,000 rev / min and also preferably 0 Hz to 600 Hz in 12-cylinder engines at a speed of about 6,000 rev / min.

The exhaust gas is supplied due to the speed / ignition timing combination pulsating with variation of the parameters frequency and pressure. As a result, caused by the pulsation vortex structures can be generated in the baffles, controlled and used targeted.

In the context of the invention, it is also possible to arrange the separating plate itself or else an additional perforated plate, with which then the volume flow or the mass flow rate of the exhaust gas from feed chamber to discharge chamber can be regulated accordingly. By deliberately moving the additional perforated plate to the separating plate, it is thus possible to change the opening cross-sections between the feed chamber and the discharge chamber, so that more or less of the exhaust gas from the feed chamber into the discharge chamber. This results in a control option for the exhaust gas heat exchanger according to the invention.

It is also possible within the scope of the invention to influence the impact point of the free jets of the exhaust gas jet on the impact point on the heat exchanger wall itself in their position by adjusting the separating plate itself or the additional perforated plate to the separating plate. Thus, for example, the free jet can impinge in a center of an inflow region or else decentralized in the inflow region, for example near a divider. It is also conceivable within the scope of the invention, by displacement of the additional perforated plate or the separating plate or by additional arrangement of guide elements, such as Strömungsleitfinnen, the free rays do not impinge perpendicular to the heat exchanger wall, but at an angle to it.

The aforementioned features can be combined with each other within the scope of the invention, with the resulting advantages. The scope of the invention is not thereby abandoned.

Further advantages, features, characteristics and aspects of the present invention will become apparent from the following description. Preferred embodiments are shown in the schematic figures. These are for easy understanding of the invention. Show it:

1 a cross-sectional view of a heat exchanger according to the invention with a thermoelectric generator,

2 a cross-sectional view of a heat exchanger according to the invention with thermoelectric generator and inflow areas,

2a a cross-sectional view according to 2 with movable additional perforated plate

3 a schematic process sequence in the arrangement of an inventive baffled heat exchanger in an exhaust line of an internal combustion engine,

4 an embodiment of the heat exchanger wall with honeycomb inflow and

5a to c variants of the exhaust gas heat exchanger with displaceable separating plate.

In the figures, the same reference numerals are used for the same or similar components, even if a repeated description is omitted for reasons of simplicity.

1 shows a heat exchanger according to the invention 1 for arrangement in an exhaust line, not shown, of a motor vehicle. The heat exchanger 1 has a heating channel 2 and a cooling channel 3 on. The heating channel 2 and the cooling channel 3 are through a heat exchanger wall 4 separated from each other. In the embodiment shown here is in the heat exchanger wall 4 a thermoelectric generator 5 integrated, the resulting temperature difference .DELTA.T between the heating channel 2 and the cooling channel 3 converted into electrical energy with the help of the Seebeck effect. Through the cooling channel 3 a cooling medium flows 6 that can be, for example, from the cooling circuit of the internal combustion engine.

According to the invention, the heating channel 2 again divided into two sections or areas, on the one hand a feed chamber 7 , on the other a discharge chamber 8th , The exhaust 9 enters the feed chamber 7 a, wherein at the feed chamber 7 this an entrance area 10 is formed, to which the exhaust line not shown here is connected. The exhaust gas flows in the exhaust gas flow direction 11 to an end 12 the feed chamber 7 and again enters through openings 13 from the feed chamber 7 in the discharge chamber 8th , The openings are in a separating plate 14 between feed chamber 7 and discharge chamber 8th introduced, wherein the separating plate 14 as a perforated plate, corrugated sheet metal or zigzag sheet that follows a sawtooth profile can be formed.

After the passage of the exhaust gas 9 through the openings 13 bounce the guided through the openings free rays 15 the exhaust gas on the heat exchanger wall 4 , From a point of impact 16 from the exhaust jets spread star-shaped in the interior 17 the discharge chamber 8th , At one end 18 the discharge chamber 8th the exhaust jets are reflected and thus centrally into an outlet channel 19 transferred and the other, not shown here, exhaust gas fed.

2 shows a basically analogous construction to the heat exchanger 1 out 1 , wherein the heat exchanger 1 a heating channel 2 and a cooling channel 3 and in the heat exchanger wall 4 a thermoelectric generator 5 is integrated. Through the cooling channel 3 also flows a cooling medium 6 and the heating channel 2 is in a feed chamber 7 and a discharge chamber 8th assigned.

Unlike the heat exchanger 1 out 1 are the feed chamber 7 and the discharge chamber 8th not bounded so that there is no end area. That through the heating channel 2 flowing exhaust gas 9 thus occurs in an entry area 10 in and in exit channel 19 out again. The embodiment according to 2 thus increases only slightly the exhaust back pressure and uses the existing pressure conditions to by means of the impact of the heat transfer between the heating channel 2 and cooling channel 3 to improve.

Furthermore, the heating channel 2 according to 2 additional inflow pipe 20 on that in the openings 13 between feed chamber 7 and discharge chamber 8th are arranged. The inflow nozzles 20 direct that from the feed chamber 7 in the discharge chamber 8th flowing exhaust gas 9 accordingly in an inflow area 21 ,

The inflow area 21 is one on the heat exchanger wall 4 delimited area. For separation are on the heat exchanger wall 4 Stege 22 arranged, which delimit or delimit the respective inflow areas. The inflow nozzles 20 are arranged so that they directly on a point of impact 16 in the middle of the inflow area 21 are oriented. From the inflow from the exhaust gas collects 9 in the discharge chamber 8th and becomes the exit channel 19 fed.

2a shows the same view according to 2 , in addition, below the Zufürhkammer 7 a perforated plate 23 is arranged. The perforated plate 23 itself again has perforated plate openings 24 on, whereby by a translatory movement 25 of the perforated sheet 23 the perforated plate openings 24 in the direction of the translatory movement 25 be moved, causing the free-rays 15 in their point of impact 16 in the inflow area 21 let move.

3 shows a flowchart that explains the schematic sequence of the resulting pressure pulsation and the interaction with a baffled heat exchanger. In 3a is a 4-cylinder internal combustion engine shown, which burns according to the 4-stroke principle fuel and produces exhaust gas. Depending on the ignition timing and the four strokes of each cylinder exhaust emission of the cylinders 1, 2, 3 and 4 is chronologically chronologically in a predetermined order. This is in 3b shown. This in turn results in the 3c illustrated pressure / time diagram, in each case the pressure at discharge of the exhaust gas from a respective cylinder for a period increases and then in turn falls. By way of example, the ignition timing of a 4-cylinder in-line engine with the ignition timing 1-3-4-2 is shown here. This is to be regarded as an endless process and additionally dependent on the load and the speed with respect to frequency and amplitude of the pressure / time diagram. This creates a pressure pulsation of the individual gas streams in the exhaust system, which together represent the total exhaust gas flow.

In 3d is that in the feed chamber 7 the heat exchanger according to the invention 1 incoming exhaust gas 9 shown, then from the feed chamber 7 in the discharge chamber 8th enters and bounces on the heat exchanger wall 4 encounters. This is followed by the exhaust gas 9 from the discharge chamber 8th further dissipated. By optimized geometric design of both the feed chamber 7 as well as the discharge chamber 8th is possible, the heat exchanger 1 optimal to the pressure pulsation of the exhaust gas 9 adapt.

4 further shows a variant of the heat exchanger wall 4 in honeycomb structure, with individual dividers 14 have a corresponding hexagonal, honeycomb-shaped arrangement to each other. Such a geometric configuration of the dividers 14 , So a honeycomb structure of the inflow 21 , has proven to be particularly advantageous for the heat transfer taking advantage of the pressure pulsation effect.

Also shown is a perforated plate 23 , which is arranged about a pivot point rotatably above the honeycomb structure. The perforated plate 23 again has perforated plate openings 24 on, which then moves the free-rays 15 upon execution of the rotational movement D within the inflow regions 21 cause. It is also conceivable with the in 4 shown perforated plate 23 translatory movements 25 to perform horizontally and / or vertically on the image plane.

5a to c show various embodiments, in which case not an additional perforated plate is arranged, but the separating plate 14 itself with a translatory displacement movement 25 opposite the inflow area 21 is displaceable.

The inflow area 21 according to 5a) is limited on the left and right image plane side by a bridge 22 , The free jet 15 enters the heat exchanger wall at a substantially vertical angle 4 in a point of impact 16 on. Thereafter, the rays are removed on the left and right sides.

In 5b is the divider 14 in contrast to 5a translational shifted, which is why the impact point 16 moved to the right on the Bilebene.

In 5c another illustration is shown in which the openings 13 of the separating plate 14 have an angle β, whereby the free jet 15 is directed so that it at an impact angle α to the point of impact 16 within the inflow area 21 impacts.

LIST OF REFERENCE NUMBERS

1

heat exchangers

2

heating duct

3

cooling channel

4

heat exchanger wall

5

thermoelectric generator

6

cooling medium

7

feeding chamber

8th

discharge chamber

9

exhaust

10

entry area

11

Exhaust gas flow direction

12

End to 7

13

openings

14

Divider

15

free jets

16

point of impact

17

Interior too 8th

18

End to 8th

19

outlet channel

20

Einströmstutzen

21

inflow

22

Stege

23

perforated sheet

24

Perforated plate openings

25

translational movement

.DELTA.T

temperature difference

D

rotary motion

α

angle of impact

β

Angle to 13

Claims (14)

Heat exchanger ( 1 ) for arrangement in an exhaust system of a motor vehicle, wherein the heat exchanger ( 1 ) a heat transfer in an exhaust gas ( 9 ) contained exhaust heat to a cooling medium ( 6 ), the exhaust gas ( 9 ) through a heating channel ( 2 ) and the cooling medium ( 6 ) through a cooling channel ( 3 ), characterized in that the heating channel ( 2 ) in a feed chamber ( 7 ) and a discharge chamber ( 8th ), wherein the discharge chamber ( 8th ) on a heat exchanger wall ( 4 ) is arranged and the heat exchanger wall ( 4 ) directly to the cooling channel ( 3 ) and the feed chamber ( 7 ) on the heat exchanger wall ( 4 ) opposite side of the discharge chamber ( 8th ) and wherein the discharge chamber ( 8th ) and the feed chamber ( 7 ) run parallel at least in sections, wherein between the feed chamber ( 7 ) and the discharge chamber ( 8th ) Openings ( 13 ) are arranged, through which the exhaust gas ( 9 ) from the feed chamber ( 7 ) into the discharge chamber ( 8th ) flows and in the discharge chamber ( 8th ) substantially perpendicular to the heat exchanger wall ( 4 ) hits and / or bounces and then through the discharge chamber ( 8th ) is dissipatable. Heat exchanger according to claim 1, characterized in that the heat exchanger wall ( 4 ) from a separating plate ( 14 ) is formed and / or that the heat exchanger wall ( 4 ) at least partially as a thermoelectric generator ( 5 ) is formed or at least partially on the heat exchanger wall ( 4 ) Thermoelectric generators ( 5 ) are arranged. Heat exchanger according to claim 1 or 2, characterized in that on the heat exchanger wall ( 4 ) in the cooling channel ( 3 ) and / or the discharge chamber ( 8th ) Heat exchanger ribs are arranged. Heat exchanger according to one of claims 1 to 3, characterized in that in the discharge chamber ( 8th ) exhaust gas ( 9 ) is reflective on one end side of the discharge channel. Heat exchanger according to one of claims 1 to 4, characterized in that the discharge chamber ( 8th ) Inflow areas ( 21 ), wherein the inflow regions ( 21 ) an area on the heat exchanger wall ( 4 ). Heat exchanger according to claim 5, characterized in that from an opening ( 13 ) from an inflow ( 20 ) in the direction of the inflow area ( 21 ) is oriented. Heat exchanger according to one of the preceding claims, characterized in that in the flow direction of the feed chamber ( 7 ) at least two openings ( 13 ) and / or inflow ( 20 ) and / or inflow regions ( 21 ) are arranged sequentially cascaded. Heat exchanger according to one of claims 5 to 7, characterized in that between the inflow ( 21 ) Dividers ( 22 ) are arranged, wherein the separating webs ( 22 ) the inflow areas ( 21 ). Heat exchanger according to claim 8, characterized in that the inflow ( 20 ) the dividers ( 22 ) undercut in the flow direction, so that the inflow ( 20 ) into the inflow area ( 21 ) protrudes. Heat exchanger according to one of the preceding claims, characterized in that the exhaust gas ( 9 ) from all inflow areas ( 21 ) from the discharge chamber ( 8th ) in a central outlet channel ( 19 ) is dissipatable. Heat exchanger according to one of claims 2 to 10, characterized in that the thermoelectric generator ( 5 ) with liquid metal to the heat exchanger wall ( 4 ) is coupled. Heat exchanger according to one of the preceding claims, characterized in that as cooling medium ( 6 ) Coolant of the engine cooling circuit is available. Heat exchanger according to one of claims 5 to 12, characterized in that the geometry of the feed chamber ( 7 ) and / or discharge chamber ( 8th ) and / or inflow ( 20 ) and / or inflow area ( 21 ) is designed and / or dimensioned such that it is connected to a pressure pulsation frequency of the exhaust gas ( 9 ) are adjusted. Heat exchanger according to one of claims 2 to 13, characterized in that the separating plate ( 14 ) is designed to be displaceable and / or that the separating plate ( 14 ) a perforated plate ( 23 ), wherein the perforated plate ( 23 ) to the separating plate ( 14 ) is relatively displaceable.

Images