DE3439891A1 - Exhaust emission control device - Google Patents

Abstract

The invention relates to an exhaust emission control device for internal combustion engines operated with leaded and/or unleaded fuel. Since in the current situation a transitional phase is to be anticipated in the case of motor vehicles, in which both leaded and unleaded fuel is used, this means a considerable shortening of the service life of conventional catalytic converters. In order to increase this service life of conventional catalytic converters, a device is created in which due to cross-section continuity as flow ducts become smaller or whether or not there are internal cross-connections the greatest possible inherent activation coupled with the smallest possible pressure loss, is achieved and in addition there is a multi-stage filtration effect for solid particles, in which clogging is largely prevented.

Description

Device for exhaust gas cleaning

The invention relates to a device for exhaust gas purification according to the preamble of claim 1.

In particular, the invention relates to a retrofit kit for Installation in vehicles that are not yet equipped with catalytic converters. the However, the device is also suitable for the eventual protection of existing catalytic converters.

Today, the ecological aspects force, especially in the transition phase, in which it is not yet ensured that all vehicles with catalytic converters and on the other hand leaded and unleaded gasoline in one still for the foreseeable future in parallel, take every precaution meet in order to be able to carry out an effective exhaust gas detoxification. As part of of this problem are currently basically three different problem areas to be taken into account.

According to the current state of the art, these are those with internal combustion engines operated vehicles which only run on leaded fuel according to DIN 51600 can be. Furthermore, these are motor vehicles that are now already unleaded Fuel can be operated, but not yet equipped with a catalytic converter are. These automobiles are normally currently running on leaded fuel operated. Furthermore, the entire problem area also includes the vehicles, although are equipped with a catalytic converter system with or without lambda probe control. These latter vehicles should run on unleaded fuel will. In a transition phase in which the offer on unleaded Fuel is relatively scarce, so should these last-named vehicles be operated with leaded fuel, as is particularly the case with cross-border Traffic is very likely still required over a long period of time.

To the exhaust gas cleaning in the aforementioned types of motor vehicle as soon as possible and to be able to perform effectively, it would be desirable to have an exhaust gas purifier to have both the protective function against downstream catalytic converters whose poisoning can take over, but also as a self-protecting one Catalyst is particularly suitable.

A device of the generic type or a corresponding method is already described in DE 31 46 004 A1.

A similar method can also be found in DE 31 49 960 A1. These known catalysts and processes are a step in the right direction Direction, which increases the service life of catalytic converters for leaded gasoline can be. This state of the art thus leads to one, albeit inadequate Protection of the catalysts used against poisoning substances such as lead and sulfur etc. The resulting extension of the service life for catalytic converters is sufficient however, it is still far from sufficient to guarantee an operating time with the greatest possible certainty of the catalytic converters for unleaded gasoline over a distance of approx. 80,000 to Guarantee 100,000 km.

The object of the invention is therefore to provide a device for exhaust gas purification to create an almost universal application with or without additional Catalytic converter, whereby above all the service life of a conventional catalytic converter, the one for reducing pollutants or eliminating them in exhaust gases from unleaded gasoline is determined, is significantly extended.

This object is achieved according to the invention by the features of the characterizing Part of claim 1 solved.

An essential core idea of the invention is to be seen in the fact that a combinatorial or synergetic effect with the device for exhaust gas cleaning is achieved by catalytically, chemically and physically acting components, wherein these individually one after the other or together during the activity of the device of operation with leaded fuel up to approximately the legally prescribed Service lives or operating kilometers of approx. 80,000 are particularly advantageous Effect is achieved by the continuity of the cross-section with decreasing size Flow channels and with or without internal cross connections with the least possible Pressure loss a maximum possible self-activation is achieved, and also a Multi-stage filtration effect for solid particles, e.g. soot, lead, etc., in the clogging is largely prevented.

The beneficial effect of the device, especially in catalytic-chemical Point of view, based above all Things on the interaction of metal oxides, preferably aluminum oxide and chromium oxide with a phosphate. The combinatorial The effect of the physical strengthening of self-activity is based on vortex shedding on transverse channels and the transitions of flow channels of different sizes, whereby however, the pressure loss compared to conventional monoliths is not or only insignificant increases.

The device advantageously consists of a heat-resistant one ceramic or metallic material, the device itself with catalytic effective materials can be coated or contains such materials. This reduces the temperature resistance of the device for exhaust gas purification the hot exhaust gases from internal combustion engines passed through them. It is particularly advantageous that by combining the self-activation with a catalytically active material an increased cleaning effect is achieved and also the service life when operating with leaded fuel compared to before known method is increased several times. In the simplest possible way the device by winding or laminating reticulated or spliced fabrics Threads, esp.

special plastics, e.g. polyethylene, polypropylene will. The device according to the invention can be designed in this way in terms of form and function that they are also suitable as a retrofit device for every type of vehicle is. Especially in the transition phase, in which also with the operation by means of leaded fuel must be expected, it is particularly useful to protect this device to use built-in lambda sensors in the motor vehicle, so that their full Functionality with regard to the pollutant reduction of the actual Catalyst remains.

When coating or otherwise integrating catalytic Active materials in the device can be the well known catalyst materials can be used, the device itself additionally or functionally independent suitable as a single unit for converting pollutants such as NOX, CO, CH or SO, n m is.

The device is advantageously constructed in block form, e.g. in the form of a replacement cartridge, as it is e.g.

is known in oil filters. The housing housing the device is therefore designed so that it is easy either longitudinally or radially Direction can be opened in order to exchange the device according to the invention to enable.

It is also possible to functionally function the device itself in several to subdivide bodies connected in series, with different effective cross-sections the flow channels can be provided in the longitudinal direction as well as in the transverse direction. Depending on the material used, the formation of the flow channels, for example, can alone in the longitudinal direction, i.e. in the flow direction of the exhaust gases, with a corresponding Sufficient porosity of the material used.

To prevent particle adsorption or the absorption of pollutants or To improve their conversion, an additional air supply can be added to those of the Exhaust gases built into the device according to the invention to be traversed route be. Appropriately, this is done in the manner of a ring channel, which in the individual Body or between the body can be guided, with a temperature control and temperature limit, if necessary, also for the downstream actual Catalyst can be provided. For optimal flow to and around the flow channels the device is suitably at the inlet duct of the exhaust gases in this device a flow divider is provided. The flow divider is expediently aerodynamic designed in the manner of an ellipsoid, the inflow cross-section being kept slightly larger is considered to be the cross section of the flow divider adjacent to the essential device. The device is also in connection with exhaust gas recirculation for reducing nitrogen oxides Can be used as an oxidation catalyst or to protect an existing catalyst system.

The invention is explained below using a schematic exemplary embodiment explained in more detail. The only drawing shows a device that is in an interchangeable housing is introduced, the overall device in Flow direction the exhaust is cut.

The device 1 for exhaust gas cleaning consists of different ones in the example Flow channels 2, the approximately continuous cross connections in the radial direction exhibit. On the other hand, a part of the device is exemplarily in the outflow area shown solely with flow channels 7 running in the longitudinal direction, which are dependent the full function of the porosity and the material used of the device able to fulfill.

In the example, the device 1 is inserted into the housing 3 in such a way that that a temperature-resistant, ceramic fabric 8 on the cylindrical outer jacket is provided. This fabric 8 has both a sealing function with respect to the inner wall of the housing as well as a compensation function with regard to dimensional differences, so that the device can be inserted into the housing with a relatively precise fit.

Since the housing is designed with a quick release system 4, can also allow easy replacement of the device. The quick release system is roughly in the manner of the other part of the housing at least partially overlapping Cylinder area designed. In this cylinder area are flange-like radially external projections are provided, which can be tensioned in the circumferential direction, for example Clamping ring can be set radially and axially.

Similar to the known catalytic converter housings for reducing pollutants in exhaust gases, the housing of the device is roughly rotationally symmetrical, with a conical enlargement or reduction on the inflow side as well as on the outflow side is provided for the transition into the connected exhaust pipe. The real one Device 1 sits in the area with the maximum radial diameter.

Provided an additional air supply to reduce the pollutants is intended, this becomes radial in the manner of a circumferential region of the device circumferential ring channel allows. From this ring channel go radially to the axis individual channels of the device.

The outer ring channel stands above an increase in volume of the housing with a bulge to the outside and corresponding connecting pieces 5 in connection. In the cylindrical jacket area of the device, a permanently elastic Bracket 6 may be provided, which for example consists of a wire mesh. Likewise can a seal made of ceramic fabric can be integrated in addition or as an alternative be built in.

In the inflow area of the device lsc advantageously a Flow divider 9 is provided for a uniform application of the downstream Device 1 provides The manufacture of the device according to the invention can preferably take place in such a way that plastic nets of different thread thicknesses are wound or stacked on top of each other to the desired final size and Final shape after slurrying with a mixture of the appropriate components and subsequent drying of the same. During the hardening and firing process the flow channels themselves then arise.

It is essential that the flow channels are connected to one another are, but nevertheless a continuous, straight flow course prevails.

The filtration effect is achieved in the device by that different particle sizes in the narrowing flow channels and Cross connections are intercepted, but still a blockage during the operating time is largely avoided.

With the possibility of using the device for exhaust gas cleaning with each to coat or catalytically active material, preferably with noble metals otherwise integrating these in it is a use as a reduction, oxidation or three-way catalyst. Without a precious metal coating, the device can to protect an existing catalyst to reduce pollutants or one Lambda probe against negative impairment through e.g. lead-containing exhaust gases in Art poisoning. The placement of the device is preferred in a housing with a quick release fastener offers the advantage of an inexpensive exchange in case of renewal.

The device can consist of a body which has several functions are assigned at the same time.

You can also create a system of individual for the respective purpose Have bodies functionally connected in series, which in the overall effect take over the full function of the device.

When using the device as an oxidation catalyst an additional exhaust gas recirculation favor the nitrogen oxide removal while the catalytic combustion of CO and CH is favored by additional air supply will. A temperature control that is possible at the same time can protect against overheating serve or also cause the device in more favorable temperature ranges is driven.

The device according to the invention is therefore suitable both for initial equipment of motor vehicles equipped with internal combustion engines, as well as for retrofitting the same. The particular advantage of the device is that it can be used universally both when driving with leaded and unleaded gasoline, especially with downstream catalytic converters whose service life is significantly longer than that previously known Tool life range is also increased.

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Claims (15)

Claims device for exhaust gas purification for with leaded and / or unleaded fuel internal combustion engines, thereby it is not noted that a cross-sectional continuity with decreasing Flow channels, (2,7) and, if necessary, internal cross connections are provided, with the lowest possible pressure loss, the highest possible self-activation of the Device is achievable, and that a multi-stage filter for solid particles, e.g. soot, lead, etc., in which clogging can be largely prevented is. 2. Apparatus according to claim 1, characterized in that g e k e n n z e i c h n e t that the device is made of heat-resistant ceramic or metallic material consists. 3. Apparatus according to claim 1 or 2, characterized in that g e k e n n z e i c h n e t that a coating with catalytically active materials, material mixtures or compositions is provided and / or that the device catalytically these contains effective materials. 44 Device according to one of claims 1 to 3, characterized ge ken n I don't show that it also contains organic compounds. 5. Device according to one of claims 1 to 4, characterized in that that it is connected upstream of a catalytic converter as an exhaust gas cleaner. 6. Device according to one of claims 1 to 5, characterized g e k e n It is noted that the flow channels (2,7) are wound or laminated by means of winding can be produced by networks. 7. Device according to one of claims 1 to 6, characterized g e k e n n z e i c h n e t that an interchangeable container as a housing (3) for receiving the device is provided. 8. Device according to one of claims 1 to 7, characterized g e k e n It is not indicated that they are made up of one or more series-connected Body is built up. 9. Device according to one of claims 1 to 8, characterized in that that an annular channel (5) as an additional air feed in or in front of the body or bodies the device with or without automatic temperature control and temperature limitation, is provided. 10. Device according to one of claims 1 to 9, characterized g e k e It is noted that a flow divider (9) in the entry area in front of the bodies is provided. 11. Device according to one of claims 1 to 10, characterized g e k e It is not noted that the coatings are all on a single body (multi-stage catalyst) are arranged. 12. Device according to one of claims 1 to 11, characterized g e k e n n z e i c h n e t that in each case a corresponding one for a given function Coating (oxidation catalyst) is provided. 13. Device according to one of claims 1 to 12, characterized g e k e n n n e i n e t that they can be used by appropriate catalytic coating Implementation of NOx, CO, CnHm, SO2 is suitable and these coatings are all on a body (multifunction catalyst) or that individual coatings for each a function (oxidation catalyst) are applied. 14. Device according to one of claims 1 to 13, characterized g e k e n n z e i c h n e t, that they consist of one body or of several Bodies can be built one behind the other and a body can be several or several Bodies each have the same or a different coating. 15. Use of a device according to one of claims 1 to 14 to extend the service life of exhaust gas cleaning catalytic converters charged with leaded fuel, in particular as a retrofit device and / or to protect one in motor vehicles built-in lambda probe and / or for the implementation of NOx, CO, CnHm, 502 due to the corresponding catalytic coating of the device.