FR2824595A1 - METHOD AND APPARATUS FOR COOLING EXHAUST GASES - Google Patents

Abstract

A method is described for cooling the exhaust gases of a motor vehicle in an exhaust gas heat exchanger (10) in which the exhaust gases (14) flow, in which the ambient air ( 18a) flowing into the area of the underbody of a vehicle during its movement is directed at an acute angle a advantageously between 20 and 70 degrees, and preferably between 35 and 550, relative to the direction of circulation of the gases of exhaust through the exhaust gas heat exchanger (10), in order to use the low temperature level of the inflowing air for the controlled elimination of the excessive thermal energy and for the cooling of the exhaust gases circulating exhaust and thus to adjust in particular as required the temperature of a catalyst device connected in series, such as for example a NOx storage catalyst.

Description

front (24) of the vehicle.

  The present invention relates to a process for the cooling of exhaust gases in automotive vehicles, in particular in automotive vehicles with a NOx accumulating catalyst / or another catalyst system. The invention relates in addition to equipment, in particular a heat changer for placing,

in the process of this process.

  GAS CALIFORGIES OF <chappemenL in general include an operaLal range opHimale lhermique relaLemementL limiLin in order to guarantee a purificaL conformation to the prescriptions of ga Exhaust conforms to the provisions, which Ge siLu for ca for 200 for example for caulul for ca eL 500 C. Below this range, the exhaust gas catalysts are not yet sufficiently active at the calalic level for fully functional glumes and to accumulate undesirable harmful subglances predisposed in the exhaust gas / or Lanstormer non harmful substances, LandiG that at the top of this beach, there first occurs an L @ G for the deactivation caused by an imporLanal lhermic alL6raLion, and even a deglrucLion of the calyzer due to the over-fall. a less serious conquest also eGL, for example, of the engines igniting by tincLionnanL spark in poor mode must often be exploited @ G with lambda = 1 of the lemp6raLures higher of exhaust gas, although the procAd of combuGLion still auororise LOW TUNING AGGOCID A LITTLE CAREURANL CONSUMPTION. ElanL gives that the lemp @ raLure of an eGL essenIllemenL dALermine dALermine by lempraLe of exhaust gases which LraversenL, conLr6l, eL in particular the limitation of the Lemp6raL of the ga of @ chappemenL by gAmE measures 1 / or targeted cooling of exhaust gases is therefore of paramount importance for the good

  operation of exhaust gas catalysts.

  In the current state of the art, methods are known for cooling the exhaust gases in the manifold area of exhaust systems in motor vehicles, in which cold air is supplied to the manifold by pressure. dynamic from the front area of the vehicle through an air line. The cold air supply can then be switched off by means of a flap. This technique is however only optimal for concepts where the collector is located at the front, in particular in motor vehicles.

transverse front.

  Exhaust systems are also known which allow increased elimination of heat in the underbody area by means of an enlargement of the area of the exhaust gas pipes, as for example

  example by forming multiple pipe installations.

  A disadvantage is, however, that the amount of heat dissipated from such a multi-pipe exhaust gas heat exchanger cannot be reduced if necessary, for example during a desulphating operation. To reduce the heat dissipated in such cases, it is known to circulate the flow of hot exhaust gases through a circulation pipe outside the multi-pipe heat exchanger or any other heat exchanger of the exhaust gases. exhaust installed and thus realize a possibility of switching the heat dissipation to the exhaust gas level. The exhaust gas valves required for this purpose are, however, extremely expensive, and of unknown operational safety over the life of the vehicle. Furthermore, heat dissipation cannot be entirely prevented, even with a switchable partitioning of the heat exchanger with respect to the underbody, since the air which escapes from the engine compartment, of a similar to that of a continuous flow heat exchanger, automatically produces a cooling effect of

the exhaust system.

  Document DE-OS-3437477 A1 describes a catalytic heat exchanger for cleaning the exhaust gases of internal combustion engines, constructed in the manner of a traditional reverse or transverse current heat exchanger, which not only allows a cooling, but also, if necessary, a heating of the catalyst coating. The heat exchanger consists of a block comprising a plurality of first circulation channels with a catalyst coating for the exhaust gases to be purified and a plurality of second circulation channels which extend transversely to these first circulation channels. circulation for a fluid heat-exchange substance, such as air or cooling water, which can be provided with electric changers for heating purposes. The circulation channels are arranged in alternating groups one above the other, each consisting of first and second circulation channels located in layers one next to the other, so that one good heat exchange is ensured. The thermal efficiency can also be controlled in a known manner by means of the quantity of substance.

  heat exchange circulating in the channels.

  The object of the present invention is to provide a simple, flexible and efficient method for cooling exhaust gases, which is not only characterized by higher cooling performance than traditional methods, but which also allows suitable heat dissipation. requirements for optimal control or adjustment of the gas temperature

  exhaust and, thereby, the temperature of the catalyst.

  Consequently, it also aims to provide a

  device for implementing this process.

  This object is achieved according to the invention in that the flowing ambient air is directed into a heat exchanger cooled by air through which the exhaust gases pass at an acute angle preferably comprised between approximately 20 and, in particular between approximately 35 and 55, with respect to the direction of circulation of the exhaust gases or to the longitudinal direction through the exhaust heat exchanger, so as to thus use the low temperature level of the air flowing in such a way as optimal as possible for the elimination of excessive thermal energy and for cooling as required by the exhaust gases. Due to the inclination chosen according to the invention of the cooling channels with respect to the longitudinal direction, naturally a substantially better air circulation is obtained in the exhaust gas heat exchanger, with a cooling performance of even greater despite a determined fraction of parallel flows in heat transfer, than a purely angled arrangement

  rights according to the current state of the art.

  In this context, the ambient air is preferably directed in the direction of the underbody area of the vehicle through the exhaust gas heat exchanger. An exhaust gas heat exchanger is preferably used comprising several exhaust and cooling gas channels arranged one next to the other alternately tranevereally to the direction of circulation of the exhaust gases, the channels cooling system each comprising in particular several individual channels arranged one behind the other in the direction of circulation of the exhaust gases. These exhaust and cooling gas channels are formed by the installation in layers of flat or corrugated sheets, the strips of the exhaust or cooling gas channels being preferably provided with recesses or thickenings in order to increase turbulence. Preferably, the exhaust outlet side of the exhaust heat exchanger is also used as the air outlet while the cooling channels are closed in the front surface or the inlet side of the exhaust pipes. exhaust gas hit by exhaust gas to minimize as much as possible

heat exchange on this side.

  In order to improve the behavior of inflow and circulation of air, the air flow is moreover preferably controlled by an air guiding device projecting from the edge, if necessary produced in a switchable manner, in particularly from baffle plates, towards the exhaust gas heat exchanger, which is preferably inclined at an angle approximately identical to that of the exhaust gas channels with respect to the longitudinal axis of the exhaust heat exchanger exhaust gas and protrudes beyond the edge of the exhaust gas heat exchanger in the direction of exhaust gas flow increasing on the air inlet side and

  decreasing on the air outlet side.

  In order to maximize efficiency and increase cooling capacity, the flow of cold air through the exhaust gas heat exchanger is preferably controlled by a controller. For the control, use is therefore made in particular of at least one first device with air flaps or lamellae at the air inlet and / or on the air outlet side, which is arranged at a determined distance and according to a inclination determined with respect to the exhaust gas heat exchanger in order to be able to conduct as large a flow of cold air as possible against the exhaust gas heat exchanger, and if necessary also against other parts of the auxiliary exhaust system. In order to improve the inflow behavior, the inclination is then chosen in particular in the opposite direction to the cooling channels. The open position of the air shutter or louvered device is preferably used as

rest position.

  For the control of the air flow, the improvement of the inflow behavior and the increase of the ground clearance, the distance and / or the inclination of the device with air flaps or slats, minus one, can be adjusted if necessary in relation to the exhaust gas heat exchanger. In order to ensure optimum ground clearance in critical driving situations, this modification is preferably carried out by means of a simple height adjustment at the rear junction point.

  of an air shutter or lamellar support.

  In addition or as a variant to the solution described according to the invention of air shutters or slats, the flow of cold air towards the exhaust gas heat exchanger can also be adjusted or modified as required by a precise air supply by means of an air duct and the removal of heat can then be controlled, for example, by modifying the air supply by means of a simple flap device of air. The air intake is then preferably carried out from the highest dynamic pressure zone in the region of the front end of a vehicle concerned, for example below a bumper, with the possibility other areas of the exhaust system, such as, for example, a catalytic converter mounted afterwards, are also cooled, if necessary, except

  the exhaust gas heat exchanger.

  In order to achieve optimum cooling, the air shutters or slats of the air shutter devices or slats are preferably controlled selectively as required, individually or in groups, by means of a control device. shutters provided for this purpose. The adjustment is carried out in particular continuously, but a switching between two extreme positions or between several intermediate positions can also be carried out. The control is then carried out as necessary according to the conditions of use of an internal combustion engine and / or of a vehicle catalyst device, the driving speed and / or the acceleration of the vehicle and / or the temperature of the catalyst and / or of the characteristic or control data of possible measurements of heating of the catalyst being also used as control parameters, so that, in conjunction with appropriate measurements at the level of the engine, an optimal temperature of the exhaust gas and catalyst is permanently guaranteed. In the method of cooling the exhaust gases according to the invention, the elimination of heat is therefore carried out in a switchable manner at the level of cold air, and not as in the current state of the art at the level of the gases 'exhaust, so that eliminates the problems described above of the known methods related to heat removal impossible to reduce when necessary or to the exhaust flaps. Due to the displacement of the exhaust gas cooling in the area of the underbody of the vehicle, the method according to the invention is also substantially more flexible and more versatile than cooling carried out according to the technique.

  traditional in the collector area.

  Due to the deposition of a suitable catalyst coating on the surfaces of the exhaust gas heat exchanger which come into contact with the exhaust gases, this can also be used simultaneously as a catalyst, in particular as NOX accumulation catalyst, and the short distance between the catalyst coating and the cold air flow and the resulting good thermal contact allow extremely efficient temperature control for the catalyst temperature, with a response time or only a minimal delay if the cooling parameters are changed. An exhaust gas heat exchanger suitable for carrying out this method of cooling the exhaust gases according to the invention comprises exhaust and cooling gas channels, the cooling channels extending according to the invention. The invention at an acute angle preferably between about 20 and 70, and in particular between about 35 and 55, with respect to the exhaust gas channels which generally extend transversely in the longitudinal direction. Several exhaust and cooling gas channels are also arranged alternately one next to the other transversely to the direction of circulation of the exhaust gases, the exhaust gas channels preferably each comprising a plurality individual channels arranged one behind the other in the direction of circulation of the exhaust gases. In a preferred embodiment, the exhaust and cooling gas channels are formed by the installation of flat and corrugated sheets, where the lamellae can be provided with recesses or thickenings in order to increase turbulence. The openings of the cooling channels are then preferably closed on the inlet side of the exhaust gases from the exhaust heat exchanger, while the outlet side of the exhaust gases is formed simultaneously as the outlet of the exhaust gases. ' cold air. The exhaust gas heat exchanger preferably comprises at least one device for guiding cold air projecting from the contour, such as for example guide plates which are preferably inclined at approximately the same angle as the cooling channels with respect to the exhaust gas channels in order to improve the behavior of inflow and circulation of air. The cold air guiding device, which can also be produced in a switchable manner, if necessary, preferably projects around the contour of the exhaust gas heat exchanger in the direction of circulation of the exhaust gases. increasing on the cold air inlet side, while it decreases protruding from the edge on the side of

cold air outlet.

  In a particular embodiment, the surface on the exhaust side of the cooling channels can also comprise a suitable catalyst coating of known type, such as for example a traditional three-way coating, an oxidation coating or a coating. of NOX accumulation catalyst, so that the exhaust gas heat exchanger according to the invention also has at the same time properties of

corresponding catalyst.

  An exhaust installation for implementing the method according to the invention described comprises a catalyst device, in particular a NOX accumulation catalyst, an exhaust gas heat exchanger of the type described mounted upstream and a device control to control the inflow of air to

  the exhaust gas heat exchanger.

  The control device here preferably comprises at least one first device with continuously adjustable air shutters, and in particular however at least one shutter device with lamellas adjustable in height and / or in inclination arranged in position adjacent to the exchanger. of exhaust gas heat at a determined distance and at a determined angle, for the production of a tranevereal or oblique inflow as strong as possible, the slats of which can be selectively controlled

  individually or in groups as needed.

  As a variant or in addition, the control device may also include a diair duct chimney which can be controlled continuously by a second device with air shutters or with slats, for a controlled supply of cold air, the inlet of which is preferably arranged in the zone of highest dynamic pressure in the front end zone of a vehicle concerned, by

example below a bumper.

  Other features, characteristics and advantages of the present invention result not only from the

  claims appended, individually and / or in

  combination, but also of the description below

  of preferred embodiments of the invention in conjunction with the corresponding drawings. In the drawings, in which similar elements are designated by the same references, in a schematic representation: FIG. 1a shows a longitudinal section of an exhaust gas heat exchanger according to the invention seen from the right side; FIG. 1B shows a cross-sectional view of heat according to the figure seen from the front; FIG. 2 shows the embodiment according to FIG. 1 with guide plates for the cold air and devices with louvered shutters which can be actuated to control the flow of cold air as required and to improve the performance of cooling; and FIG. 3 shows the embodiment according to FIG. 2 with an air inlet directed by means of an air duct chimney which can be controlled in order

  optimize cooling performance.

  FIG. 1a shows an exhaust gas heat exchanger 10 with a front side for the entry of the exhaust gases 10a (represented on the left in the drawing), a rear side in opposition to the exit for the exhaust gases 10b and several parallel exhaust gas channels 12 which extend transversely in a longitudinal direction between these two sides 10a and 10b for the exhaust gases from an internal combustion engine (not shown), in particular a direct injection engine, of a motor vehicle (also not shown). The hot exhaust gases which flow, symbolized for the sake of clarity by an arrow 14, therefore penetrate from the front into the exhaust gas heat exchanger 10 via the inlet side of the exhaust gases. exhaust 10a, they pass through it in a longitudinal direction through the exhaust gas channels 12, where they are cooled as required in accordance with the explanations below by thermal contact with cold air, and they then exit at a temperature level duly lowered as required through the rear exhaust gas outlet side 10b. From this moment, they can be led to a subsequent NOX accumulation catalyst (not shown) and / or to another catalyst device for purifying the exhaust gases.

according to regulations.

  The exhaust gas channels 12 are provided on their surface which comes into contact with the exhaust gases with a coating of NOX accumulation catalyst, so that the exhaust gas heat exchanger 10 makes simultaneously functions as a NOX accumulation catalyst. However, it is also possible to deposit only, for example, a simple oxidation coating, such as palladium and / or platinum, or a three-way catalyst coating, such as palladium and / or platinum and / or rhodium, which provides the exhaust gas heat exchanger 10 with corresponding catalyst properties. Of course, the exhaust gas heat exchanger 10 can however also be produced only as a simple heat exchanger

  without additional catalyst properties.

  A plurality of transverse cooling channels 16 extend at an acute angle of about 50 relative to the longitudinal direction or to the direction of flow of the exhaust gases obliquely from bottom to top through the heat exchanger exhaust gas 10. On the inlet side of the exhaust gas 10a, the openings of these cooling channels 16 are closed, however, so that the exchange of cold air with the environment is essentially limited to the sides lower and upper lOc

  and l0d from the exhaust gas heat exchanger 10.

  Due to the cooling channels 16 inclined towards the rear, the lower side lOc acts as an inlet for the cold air, while the upper side lOd acts as an outlet for the cooling air. The outlet side of the exhaust gases 10c is also designed as an outlet for cooling air since the cooling channels 16 which open into it are not closed. It therefore acts simultaneously as an output for

  exhaust gases and cooling air.

  Ambient air flowing mainly from the underbody area during movement, symbolized for the sake of clarity by an arrow 18a, therefore flows into the lower side or the cold air inlet side lOc of the heat exchanger exhaust gas heat 10 in the rear-angled cooling channels 16, through which it is led obliquely from bottom to top through the exhaust gas heat exchanger 10 to the rear, where it absorbs, due to thermal contact with the adjacent exhaust gas channels 12, thermal energy from the exhaust gases which circulate therein and therefore cools them accordingly. The air thus reheated emerges slightly backwards from its entry point, substantially on the upper side or the cold air outlet side lOd of the exhaust gas heat exchanger 10 ( with regard to the small protrusions on the outlet side of the exhaust gas 10b of the cold air which circulates in the exhaust gas heat exchanger 10, reference is made here to the

  description for Figure 2), which is symbolized

  by an arrow 18b. At its outlet, it mixes with ambient air circulating in the exhaust gas heat exchanger 10 and thus transfers the energy again

  thermal extraction of exhaust gases from the environment.

  In the transverse section of the exhaust gas heat exchanger 10 seen in the direction of circulation of the exhaust gases shown in FIG. 1b, it can be seen that exhaust and cooling gas channels 12 and 16 are arranged side by side alternately in the tranevereale direction. The six exhaust gas channels 12 shown, which each extend over the entire height of the exhaust gas heat exchanger 10, are each delimited by the installation of two spaced layers of metal sheets planar, while the seven adjacent cooling channels 16 consist of interleaved layers of corrugated sheets, which in each case form a plurality of individual channels arranged one behind the other. In order to increase turbulence and optimize heat transfer, the slats are also provided

  sinking or thickening.

  Through the cooling channels 16 inclined obliquely towards the rear at an acute angle relative to the longitudinal direction of the exhaust gas heat exchanger 10 according to the invention, the penetration of the ambient air 18a flowing substantially from the longitudinal direction, is largely favored over traditional exhaust heat exchangers with their arrangement at right angles to the cooling channels, so that a cold air efficiency is obtained all the more important, which naturally in turn generates significantly better cooling performance than in the current state of the art. A further improvement in these cooling performances can be achieved with the embodiment according to the invention shown in FIG. 2, which includes an additional guide device 24 for the circulation of cold air and an additional control device 26 for the flow of cold air 18a, which allows continuous control according to

  cooling performance needs.

  Figure 2 shows the exhaust gas heat exchanger 10 according to Figure 1 as part of an exhaust system 20, which is traditionally installed in the underbody area of a motor vehicle only represented by the outline 22 of a thermal protection plate, and which comprises a NOX accumulation catalyst (not shown) and / or another catalyst device mounted in series on the exhaust gas heat exchanger 10 The front side or the inlet side of the exhaust gases 10a of the exhaust gas heat exchanger 10, closed for the inflow of cold air, is additionally protected against the influx of ambient air 18a by the exhaust system 20 which extends to the obviously larger dimensions of the exhaust gas heat exchanger 10, so that the heat exchange with the exhaust gases 14 which circulate is minimized on this side of the exhaust gas heat exchanger 10. On the rear side or the exhaust side of the exhaust gas 10b, on the other hand, the open cooling channels 16 which terminate there emerge in the installation exhaust 20, so that the cooling air 18b exiting at this location mixes with the exhaust gases by directly cooling the exhaust gases 14 which exit from the exhaust gas channels also emerging at this location and is directed , joined thereto, through the exhaust installation 20 of the catalyst device mounted in succession. According to the invention, in order to improve the penetration and circulation behavior of air and thus optimize the elimination of heat, the exhaust gas heat exchanger 10 is provided with a plurality of sheets of guide 24, projecting one behind the other at an equal distance in the direction of circulation of the exhaust gases, which are each installed on the side opposite the flow of exhaust gases from the cooling channels on the outer side of the exhaust gas heat exchanger 10 and extend parallel to the cooling channels 16 transversely thereto. The guide plates 24 are inclined at approximately the same angle of approximately 50 as the cooling channels 16 relative to the longitudinal direction of the exhaust gas heat exchanger 10, so that, during movement, the ambient air 18a which flows mainly in the longitudinal direction is captured and directed obliquely from the bottom upwards along the exhaust gas heat exchanger 10, which naturally causes a corresponding cooling of the heat exchanger exhaust gas 10 and exhaust gas 14 flowing therein. For a better capture and direction of the flowing air 18a, the guide plates 24 or deflectors are made so that at the start, they do not protrude, then they protrude increasingly on the edge of the exhaust gas heat exchanger 10 in the direction of circulation of the exhaust gases on the lower side or the cold air inlet side 10C, while they protrude decreasingly, and finally do not no longer protrude in a certain end area, on the upper side or the side of

cold air outlet lOd.

  Below and above the exhaust gas heat exchanger 10 is arranged in each case a lamellar shutter 26a and 26b, which comprises a plurality of individual lamellas 28a and 28b which can be controlled individually and adjusted continuously and which extend over the entire length and width of the exhaust gas heat exchanger 10. With a view to improving its operation, the lamellar flaps 26a, 26b are inclined in the opposite direction to the baffle plates 24 relative to the longitudinal axis of the exhaust gas heat exchanger 10 or horizontally. In order to appropriately modify the inflow behavior and guarantee optimal ground clearance in critical driving situations, the louvered shutter 26a is made in adjustable height, and therefore also in inclination, at the junction point. rear of a slat support (not shown). Correspondingly, the upper louvered shutter 26b can also be produced.

  adjustable in height and tilt.

  In order to increase the ground clearance, one of the two flap shutters 26a or 26b can however possibly be omitted. In addition, the exhaust gas heat exchanger according to the invention can also for this purpose be mounted in rotation by 90 and the louvered flaps 26 can be arranged laterally to the exhaust gas heat exchanger 10 , so that the cold air no longer circulates in it obliquely from bottom to top, but rather at a determined angle in the horizontal direction. If necessary, additional air or louvered shutters 26 or of another embodiment can also be used and suitably arranged to achieve a sufficient inflow 18a into the exhaust gas heat exchanger 10 or a

  partitioning appropriate to the needs against this influx.

  In addition to the lamellar flaps 26 (or where appropriate, as an alternative to them), at least one other comparable lamellar flap 26 or any air flap device can also be arranged adjacent to the storage catalyst. NOX (not shown) or other catalyst device and used for precise control of air circulation for cooling

  additional direct from the catalyst as required.

  Figure 2 shows the open or default open position of the two louvered flaps 26, in which the different louvers 28 of the louvered flaps 26 are all fully open so that the ambient air flowing in the longitudinal direction, again symbolized by an arrow 18a, is capped by the slats 28a in the oblique position of the lower louvered flap 26a and modified in its direction of circulation so that it is directed obliquely from bottom to top through the air channels cold 16 by cooling the exhaust gases 14 which circulate in the exhaust gas channels 12, before finally exiting on the upper side or the air outlet side lOd of the exhaust gas heat exchanger 10. A part of the relatively cold ambient air Ib which flows is however also directed upwards, substantially parallel to the baffle plates 24 along the external side of the heat exchanger. exhaust gas hauler 10, which causes additional substantial cooling of the exhaust gas heat exchanger 10 and the exhaust gases 14 which circulate therein and terminate there, in conjunction with the cooling effect already described due to the circulation of cold air, to the reduction or at least the desired limitation of the temperature of the exhaust gases, and therefore

  also the temperature of the catalyst.

  Depending on the conditions of use of the assistant internal combustion engine (not shown) of the motor vehicle, such as for example the driving speed and / or the acceleration of the vehicle, and / or the conditions of use of the mounted catalyst device in series, such as for example the temperature of the catalyst or the characteristic or control data of possible measurements of heating of the catalyst, the louvered shutters 26 are fully or partially closed in order to reduce the cooling, to reduce the air resistance or to weaken the noise emissions by means of a selective control of the different slats 28 or of different groups of slats by means of an assistant shutter control device (not shown). The control is carried out continuously, but switching between two extreme positions and / or switching between specific additional intermediate positions is also possible. In the event of complete closure (not shown) of the louvered shutters 26, the inflowing air which strikes the louvered shutters 26 is essentially completely directed next to the exhaust gas heat exchanger 10 and cooling corresponding of the exhaust gas heat exchanger is thus avoided

  under specified conditions of use.

  An additional increase in cooling performance can be obtained with the embodiment according to the invention illustrated in FIG. 3, in which the air 18a used for cooling is directed by an additional air duct chimney 30 on the lower louvered shutter 26a. The inlet 32 of the air duct chimney 30 is then in the area of highest dynamic pressure in the front end area 34 below a bumper of the vehicle. It is provided with a continuously adjustable switching flap 36 for the precise continuous control of the air flow. In addition, the outline of a front wheel 38 is also shown. The air duct chimney 30 can be used not only as a supplement, as in the illustrated case, but also as an alternative to the simple solution to

  air or louvered shutters as shown in Figure 2.

  The inventive idea has been explained above by way of example with reference to a particular embodiment of an exhaust gas heat exchanger 10 according to the invention and of a device for controlling or guiding the cold air 16, 24 or 26, 30, 36 for the precise control of the behavior of inflow, penetration and circulation of cold air. Of course, exhaust gas heat exchangers 10 of another embodiment comprising cooling channels 16 and / or cold air guiding devices 24 made or otherwise inclined can also be used for the implementation of the method according to the invention. In order to optimize the process, suitable control devices 26, 30, 36 of another embodiment can of course also be produced for the precise control of the inflow behavior. As already mentioned, a catalyst device of the exhaust system 20 connected in series can for example also be cooled directly by means of ambient air and the cooling performance, and therefore also the temperature of the catalyst, can thus be controlled as required by means of control or guiding cold air ad] anointed corresponding.

Claims (49)

REVENDI CATIONS   1. A method of cooling the exhaust gases of a motor vehicle in an air-cooled exhaust gas heat exchanger (10) in which the exhaust gases circulate, characterized in that the ambient ambient air (18a) is directed at an acute angle to the direction of air flow of the exhaust gases through the gas heat exchanger exhaust (10).   2. Method according to claim 1, characterized in that   that the angle is between 20 and 70.   3. Method according to claim 2, characterized in that   that the angle is between 35 and 55.   4. Method according to one of the preceding claims,   characterized in that the blowing air (18a) is directed in the direction of the underbody area of the vehicle (22) through the gas heat exchanger exhaust (10).   5. Method according to any one of the claims   above, characterized in that an exhaust gas heat exchanger (10) comprising several exhaust and cooling gas channels (respectively 12 and 16) arranged side by side alternately and transversely to the direction of gas flow exhaust is used.   6. Method according to claim 5, characterized in that the cooling channels (16) each comprise several individual channels arranged one behind the other   in the direction of exhaust flow.   7. Method according to claim 6, characterized in that the exhaust and cooling gas channels (12 and 16) are formed by the installation of layers of flat and corrugated sheets (respectively 12a and 12b).   8. Method according to claim 7, characterized in that the strips of the exhaust gas channels and / or cooling (respectively 12 and / or 16) are provided with recesses or thickenings in order to increase turbulence.   9. Method according to any of the claims   previous, characterized in that the exhaust gas outlet side (lOc) of the gas heat exchanger   exhaust (10) is used as the air outlet.   10. Method according to any of the claims   previous, characterized in that the air circulation and / or the air penetration in the exhaust gas heat exchanger (10) are controlled by at least one protruding air guide device (24) on the   edge on the exhaust gas heat exchanger (10).   11. Method according to claim 10, characterized in that the air guiding device (24), at least one in number, projects increasingly in the direction of circulation of the exhaust gases on the side d air inlet (lOc) and decreasingly on the air outlet side (lOd) relative to the edge of the heat exchanger exhaust gas heat (10).   12. Method according to one of claims 10 and 11,   characterized in that baffle sheets are used   as at least one air guiding device (24).   13. Method according to any one of the claims   above, characterized in that the flow of circulating air (18a) into the exhaust gas heat exchanger (10) is controlled by a command (26, 30, 36).   14. Method according to claim 13, characterized in that at least one first device with air deflector flaps or lamellae (26a, 26b) on the air inlet side and / or on the air outlet side air (lOc and lOd respectively) is used as a control device (26, 30, 36), which is arranged at a determined distance and at a determined inclination relative to the heat exchanger exhaust gas (10).   15. Method according to claim 14, characterized in that the open position of the first shutter device   air or slats (26) is chosen as the rest position.   16. Method according to claim 15, characterized in   that the first at least one air shutter or flap device (26) is inclined in direction   opposite of the cooling channels (16).   17. Method according to one of claims 14 to 16,   characterized in that the distance and / or the inclination of the first at least one air shutter or slat device (26) can be changed if necessary relative to the heat exchanger of gas exhaust (10).   18. Method according to claim 17, characterized in that the distance and / or the inclination of the first air shutter device or lamellae (26), at least one in number, are adjusted at the rear articulation point a   corresponding support for louvered shutters.   19. Method according to any one of the claims   previous, characterized in that the inflow of ambient air (18a) to the exhaust gas heat exchanger (10) is controlled by a suitable air supply by means of at least one duct chimney air (30).   20. The method of claim 19, characterized in that the air intake takes place through the air duct chimney (30) at least one, from the dynamic pressure zone to the front end (34) of the vehicle.   21. Method according to one of claims 19 and 20,   characterized in that the air flow through the air duct (30), at least one in number, is controlled by a second air shutter device or slats (36).   22. Method according to one of claims 14 to 21,   characterized in that the settings of the shutter devices   air or slats (26, 36) are continuously controlled.   23. Method according to one of claims 14 to 22,   characterized in that the air flaps or slats (28) of the air flap or slat devices (26, 36) are selectively controlled individually or in groups.   24. Method according to one of claims 13 to 23,   characterized in that the control is carried out as a function of the conditions of use of an internal combustion engine and / or of a vehicle catalyst device, the driving speed and / or the acceleration of the vehicle and / or the temperature of the catalyst and / or the characteristic or control data of possible catalyst heating measurements being used as control parameters.   25. Method according to any of the claims   previous, characterized in that the exhaust gas heat exchanger (10) is also used as an exhaust gas catalyst due to the deposition of a suitable catalyst coating on the surfaces which   come into contact with the exhaust gases.   26. Exhaust gas heat exchanger (10) for motor vehicles comprising exhaust and cooling gas channels, characterized in that the cooling channels (16) extend at an acute angle to the channels exhaust gas (12). 27. Exhaust gas heat exchanger (10) according to claim 26, characterized in that the angle is between 20 and 70.   28. Exhaust gas heat exchanger (10) according to claim 27, characterized in that the angle is between 35 and 55.   29. Exhaust gas heat exchanger (10)   according to one of claims 25 to 28, characterized in   that the cooling channels (16) extend to the oblique from the bottom to the top.   30. Exhaust gas heat exchanger (10)   according to one of claims 26 to 29, characterized in that   that the exhaust and cooling gas channels (respectively 12 and 16) are arranged side by side alternately transversely to the direction of exhaust gas circulation.   31. Exhaust gas heat exchanger (10)   according to one of claims 26 to 30, characterized in that   that the cooling channels (16) comprise several individual channels arranged one behind the other   in the direction of exhaust flow.   32. Exhaust gas heat exchanger (10)   according to one of claims 26 to 31, characterized in that   that the exhaust and cooling gas channels (respectively 12 and 16) are formed by   the installation of layers of flat and corrugated sheets.   33. Exhaust gas heat exchanger (10) according to claim 32, characterized in that the strips of the exhaust gas channels and / or cooling (respectively 12 and 16) are provided with recesses or thickenings to increase turbulence. 34. Exhaust gas heat exchanger (10)   according to one of claims 26 to 33, characterized in that   that the exhaust gas outlet side (10b) of the exhaust gas heat exchanger (10) is also designed as a cooling air outlet 35. Exhaust gas heat exchanger (10)   according to one of claims 26 to 34, characterized by at   minus a protruding cold air guide device on the edge (24).   36. Exhaust gas heat exchanger (10) according to claim 35, characterized in that the cold air guiding device projecting on the edge (24), at least one in number, protrudes on the edge of the exhaust gas heat exchanger (10) in the direction of flow of the exhaust gas to an increasing extent on the cold air inlet side (lOc) and decreasing on the outlet side cold air (lOd). 37. Exhaust gas heat exchanger (10)   according to one of claims 35 or 36, characterized in   that the cold air guide device (24), at least one in number, includes deflecting sheets for cold air. 38. Exhaust gas heat exchanger (10) according to claim 37, characterized in that the deflecting sheets for cold air (24) are inclined at the same angle as the cooling channels (16) by   relative to the exhaust gas channels (12).   39. Exhaust gas heat exchanger (10)   according to one of claims 26 to 38, characterized in that   that the exhaust side surface of the exhaust gas channels (12) includes a catalyst coating. 40. Exhaust installation for motor vehicles comprising: - a catalyst device; - an exhaust gas heat exchanger (10)   mounted upstream according to one of claims 26 to 39; and   - a control device (26, 30, 36) for controlling the flow of air (18a) towards the heat exchanger exhaust gas (10).   41. Exhaust installation according to claim 40, characterized in that the device for   catalyst includes a NOX accumulation catalyst.   42. Exhaust installation according to one of   claims 40 and 41, characterized in that the   control device (26, 30, 36) comprises at least a first air shutter or lamella device (26) arranged in position adjacent to the gas heat exchanger exhaust (lo).   43. Exhaust installation according to claim 42, characterized in that the first air shutter or lamella device (26), at least one in number, is inclined in the opposite direction of the cooling channels (16) of the gas heat exchanger exhaust (10).   44. Exhaust installation according to one of   claims 42 and 43, characterized in that the distance   and / or the inclination of the air shutter device or slats (26), at least one in number, relative to the exhaust gas heat exchanger (10), can be settled.   45. Exhaust installation according to one of   claims 40 to 44, characterized in that the   control device (26, 30, 36) comprises at least one air duct chimney (30) for the precise arrival cold air.   46. Exhaust installation according to claim 45, characterized in that the inlet (32) of the air duct chimney (30) is arranged in the dynamic pressure zone at the front end (34) of a motor vehicle.   47. Exhaust installation according to one of   claims 45 and 46, characterized in that the chimney   air duct (30) comprises a second device with air flaps or slats (36) for controlling the air circulation.   48. Exhaust installation according to one of   claims 42 to 47, characterized in that the   air flaps or lamella (26, 36) are adjustable in conLinn.   49. Installation of a 4-stage exhaust system, one of the claims 42 48, characteristic in that the air flaps or slats (28) of the air flap arrangements on slats (26, 36) can be controlled.