DE102006043086A1 - Use of a reducing agent-generating system, in particular as auxiliary heating - Google Patents

Abstract

The invention relates to a reducing agent-generating system of an exhaust system of a motor vehicle, with a heating element that generates heat necessary for the operation of the system. There is provided a heat coupling element (55) which selectively conducts the heat or a portion thereof to at least one non-system device (59) of the motor vehicle.

Description

The The invention relates to a reducing agent-generating system Exhaust system of a motor vehicle according to the preamble of the claim 1.

was standing of the technique

In automotive technology, selective catalytic reduction (SCR) devices are known for removing nitrogen oxides (NO _x ) in oxygen-containing exhaust gases and reducing them to nitrogen and water. As a reducing agent, ammonia (NH ₃ ) is preferably used for this purpose. For mobile applications, it is not advisable for safety reasons to carry large amounts of ammonia in the vehicle. Therefore, it is produced from uncritical substances by means of a reducing agent-generating system (RGS) on board, ie in the vehicle, and used for exhaust gas treatment. In order to generate the reducing agent from the mentioned uncritical substances, the use of heat is required. As a result, such a reducing agent-generating system has a heating element which provides the necessary heat for the operation of the system.

advantages the invention

by virtue of of the reducing agent-generating according to the invention Systems can be existing components cost-saving and / or to Magnification of a Use variety in the course of a dual function in which the heating element of the reducing agent-generating system (hereinafter called system) also used to heat to lead to at least one non-system device. This is a heat coupling element provided that selects the heat generated by the heat element selectable either supplies the components that generate the reducing agent, or at least one non-system facility. It is also conceivable that the heat delivered to both modules at the same time. The heating element is therefore for another purpose, namely used heating of non-system facilities of the vehicle.

To a development of the invention is provided that the heat element as a hot gas supplying heating element is trained. The hot gas, which preferably comes from a burner, is therefore on the Heat coupling element supplied to the non-system device, provided that mode required becomes. The mentioned in claim 1 Word "selectable" accordingly means that a switch possibility the heat exists only when needed by means of the heat coupling element to supply the non-system device.

Further it is advantageous if the heat coupling element a gas flow path for the hot gas. If the feeder from heat to non-system facility desired becomes, is accordingly the hot gas introduced into the gas flow path and thereby reaches the site of use.

When system-foreign device comes in particular an interior heating a passenger compartment of the motor vehicle into consideration. Additional or Alternatively, it can be provided that the system-foreign device an internal combustion engine of the motor vehicle. Consequently, can be with the heat of the heating element the passenger compartment of the motor vehicle and / or the internal combustion engine of the motor vehicle. This is especially before the startup phase the internal combustion engine advantageous because a warm start of the engine, especially in winter, this considerably protects and the environmental impact and can reduce fuel consumption.

A Development of the invention provides that the gas flow path the heat coupling element with a heat exchanger, in particular a stationary heating heat exchanger, a cooling water circuit of the motor vehicle is connectable. The heat of the heating element is selectable the auxiliary heating heat exchanger supplied causing the cooling water of the motor vehicle is heated. As a result, the One heats the internal combustion engine and on the other hand, a heating heat exchanger can be operated can, which is in the cooling water circuit is located and therefore heat is provided for heating the passenger compartment. This increases the temperature comfort of the occupants and the traffic safety, since the windows of the passenger compartment do not fog up, the driver no extended Reaction time at low temperatures and this while driving Do not wear thick clothes.

Further advantageous embodiments of the system will become apparent from the claims.

Further The invention relates to a method for operating a reducing agent-generating system an exhaust system of a motor vehicle, with a heating element, that for generates the heat necessary for the operation of the system, whereby the of the heating element generated heat or a portion thereof also for heating at least one non-system Device of the motor vehicle is used.

advantageous Further developments of the method emerge from the claims.

Further The invention relates to a motor vehicle with a reducing agent-generating System according to the preceding Versions.

Finally, concerns the invention the use of a heat element of a reducing agent-generating System of an exhaust system of a motor vehicle also for the purpose the warming at least a non-system device of the motor vehicle.

The The invention will be explained in more detail below with reference to the drawings. It demonstrate

1 a schematic representation of the reducing agent-generating system

2 to 5 schematic representations of the reducing agent-generating system according to further embodiments of the invention.

1 shows a reducing agent-generating system (RGS) assigned to a vehicle (not shown) 1 , the two entrances 3 and 5 having. These belong to a nitric oxide generator unit, which can be realized by a thermal plasma, in particular with a so-called plasmatron 7 with an integrated heating element 9 , which is designed as a starting burner. A plasmatron is a plasma generating system whose plasma zone is superimposed by a gas flow and is used scientifically or technically outside of a plasma generation unit. The plasmatron 7 has an output. This is with a turnoff 11 which divides the path into two parts, namely a standard path 13 and a parking heater 15 ,

In the standard way 13 there is a shut-off element 17 , which is designed as a 2-2 valve. This is followed by another turnoff 19 at the parking heater 15 after passing through a heat exchanger 37 back to the standard way 13 meets. This is followed by a catalytic component 21 connected to an ammonia generator unit 23 , hereinafter referred to as AGC for Ammonia Generating Catalyst or simply referred to as NH ₃ generator.

Furthermore, an exhaust system 25 present to an internal combustion engine 27 vehicle connected to a Diesel Oxidation Catalyst (DOC) 29 connected is. This is followed by a diesel particulate filter (DPF) 31 and an SCR device 33 , which is used to remove nitrogen oxides in oxygen-containing exhaust gases and reduce them to nitrogen and water. The reducing agent used is ammonia produced by the ammonia generator unit (AGC). 23 is produced. Between the DPF 31 and the SCR facility 33 is a junction 35 provided the AGC 23 with the exhaust system 25 in the area between the diesel particulate filter 31 and the SCR facility 33 connected.

Follow the parking heater path 15 so is the turn off 11 the heat exchanger 37 connected. This can be formed for example as a parking heater heat exchanger. From this heat exchanger 37 Coming is a return 39 provided with the branch 19 is linked. There the parking heater closes 15 back to the standard way 13 at. The heat exchanger 37 is with a cooling water circuit 41 connectable / connected the motor vehicle.

With the internal combustion engine running 27 is used in the operation of the reducing agent generating system (RGS) 1 Diesel fuel and air / exhaust gas at the entrances 3 . 5 fed. In the plasmatron 7 with integrated heating element 9 Nitrogen oxides are generated in a lean phase. The gas mixture is heated. After the exit, the heated gas mixture, the so-called hot gas, hits the branch 11 and then in the standard way 13 on the shut-off 17 , In standard operation, the shut-off element 17 open. The hot gas is passed through the catalytic component 21 directed. This is during a fatty phase in the area of the plasmatron 7 Metered fuel to a hydrogen and CO-containing gas mixture. Thereafter, the hot gas through the AGC 23 where to operate the SCR facility 33 necessary ammonia is generated. The catalytic component 21 requires to operate a temperature of 250 ° C-800 ° C, preferably 650 ° C, while operating the AGC 23 a temperature of 150 ° C-350 ° C, preferably 250 ° C is necessary. The heat required for this supplies the heat element 9 heated hot gas. The ammonia is over the confluence 35 in the exhaust system 25 and in the SCR facility 33 used for the exhaust gas treatment.

Before the start of the internal combustion engine 27 becomes the RGS 1 Not required in the above manner. According to the invention, however, the still put into operation heat element 9 use, ie the heat element 9 supplies hot gas. The heat of the hot gas can in particular when not using the RGS 1 for heating systems outside the system 59 of the motor vehicle, namely the internal combustion engine 27 and / or a passenger compartment of the motor vehicle, which in the 1 not shown, are used. For this purpose, a heat coupling element 55 , which diverts the heat into a usable form for this purpose. This includes according to 1 the turnoff 11 , an introduction 57 of the parking heater 15 , the heat exchanger 37 , the repatriation 39 , the diversion 19 and the shut-off element 17 , Will the shut-off element 17 closed, the hot gas is over the lead 57 in the heat exchanger 37 directed. In the heat exchanger 37 finds a heat exchange with the cooling water of a cooling water circuit 41 the internal combustion engine 27 instead of. The heat shear 37 forms in particular a parking heater, ie it is used for heating of non-system facilities 59 of the particular non-moving motor vehicle. The heated cooling water is used for heating (preheating) of the internal combustion engine 27 used. Furthermore, in the cooling water circuit 41 a heating heat exchanger may be provided, which uses the heat of the cooling water for heating the passenger compartment. The hot gas is then added to the RGS 1 returned, namely on repatriation 39 in the turnoff 19 , And finally enters the exhaust system of the internal combustion engine 27 , Accordingly, the heat coupling element 55 a gas flow path 61 for the hot gas on.

The core of the invention is accordingly, the starting burner of the RGS 1 to use as a heater. As a result, for example, the internal combustion engine 27 preheated and / or the passenger compartment of the motor vehicle to be preheated. Accordingly, if the starting burner of the RGS 1 (Ammonia generator) is not needed, so in particular before a start of the internal combustion engine, it is available for the new, inventive purpose. The auxiliary heater is used, among other things, the temperature comfort of the occupants. However, it also serves road safety, as it does not fogged windows and does not lead to a prolonged reaction time of the driver due to low temperatures. This also does not need unnecessarily thick clothing. The possible by the invention warm start of the engine, especially in winter protects the components and can (with a correspondingly low-emission auxiliary heater) reduce the environmental impact and fuel consumption. Furthermore, the resale value of the vehicle is increased by the auxiliary heater.

In normal operation of the RGS (using the standard path 13 ) NH ₃ is prepared from the educts NO and H ₂ . NO is in a lean phase (in air or exhaust mode with λ> 1) in a Plasmatron 7 generated in air. These nitrogen oxides then flow through the catalytic partial oxidation stage (cPOx) and in the downstream subsequent catalytic unit (NH ₃ - producers) are stored. In a subsequent to the lean phase, the second phase of operation, the fat phase (0.33 <λ <1), is in the range of Plasmatrons 7 liquid fuel is metered into an evaporation and mixture-forming zone and converted in the cPOx stage (Catalytic Partial Oxidation) to a H ₂ and CO-containing gas mixture, which then converts the stored nitrogen oxides to ammonia at the NH ₃ generator. This gaseous ammonia produced in a secondary line is then metered into the full flow of the exhaust line before the SCR catalyst. Since the SCR catalyst has an NH ₃ storage capacity, it is possible to continuously achieve the reduction of the nitrogen oxides by means of an SCR process in the exhaust gas full flow, even via a discontinuous process for producing ammonia. In the temperature range between 150 ° C and 450 ° C, the catalysts of titanium dioxide (TiO ₂ ) and vanadium pentoxide (V ₂ O ₅ ) convert the nitrogen oxides with the ammonia produced at a high rate.

The invention is accordingly based on the fact that hot combustion gases of the starting burner are used in the auxiliary heating mode. In the case of NH ₃ demand, the auxiliary heating path becomes 15 no longer used, but the standard way 13 so that the system can be operated again as NH ₃ generator. It is also a mixed operation conceivable, so both NH ₃ production as well as the heating systems of other systems 59 ,

The embodiment of 2 is essentially the same as the 1 , The reference numbers of 2 correspond to those of 1 so that a detailed description is omitted. The object of 2 differs only in that instead of a 2-2 valve, a linear valve as a shut-off 17 is used, which allows only a partial flow of the hot gas through the heat exchanger 37 to conduct and thus the temperature of the catalytic component 21 (cPOx stage) through the other partial flow of the hot gas. This can greatly reduce the HC and CO emissions of the entire burner exhaust gas after reaching a light-off temperature.

Also 3 corresponds in many parts of the arrangement in 1 so that a detailed description is omitted. Again, the reference numbers are those of the description 1 correspond. One difference is that the diversion 11 after the catalytic component 21 is provided. It follows as in 1 in the standard way 13 a shut-off element 17 and then the turnoff 19 at the parking heater 15 back to the standard way 13 meets. In this case, the catalytic component becomes 21 in any case (including in the auxiliary heating operation) flows through the hot gas and is operational. This also results in a strong reduction of HC and CO emissions.

4 is also similar in many parts 1 , Again, the reference numerals correspond to the description of 1 those of 4 , A difference too 1 is that in the parking heater 15 the hot gas after passing through the heat exchanger 37 not in the standard way 13 in front of the ammonia producer unit 23 is returned, but directly into the exhaust system 25 before the SCR facility 33 is introduced. There are two valves 45 and 47 (especially two 2-2 valves) provided. The valve 45 is located between the AGC 23 and the confluence 35 in the standard way 13 , The valve 47 is in the parking heater path 15 between the heat exchanger 37 and a junction 43 provided, which is located in the exhaust system 25 before the SCR facility 33 located. Depending on the setting of the valves 45 and 47 can the hot gas either through the standard route 13 and / or by the parking heater path 15 be directed.

In 5 is another possible arrangement of the invention to see. Again, the reference numerals used correspond to those of the description of 1 so that a detailed description is omitted. Notwithstanding here is a valve not shown in detail 49 that is between the catalytic component 21 and the AGC 23 is arranged. From the valve 49 In addition, a connection 51 to the exhaust system 25 (between internal combustion engine 27 and catalyst 29 ) and the return 39 of the parking heater 15 is also with the valve 49 coupled. The valve 49 can be designed as a 4-4 valve, wherein intermediate positions may be possible, as is possible for example in a linear valve. Depending on the settings, which are referred to below as settings a, b, c, d, setting a will become the default path 13 run through. With setting b is the catalytic component 21 about the connection 51 with the exhaust system 25 coupled. The hot gas in this case is directly above the catalytic component 21 and the connection 51 in the exhaust system 25 directed. With setting c is over the connection 51 the exhaust system 25 with the AGC 23 connected. The exhaust gas gets out of the engine 27 about the connection 51 into the AGC 23 directed. With setting d becomes the parking heater 15 pass through, wherein the hot gas in this arrangement around the catalytic component 21 is routed around and at the valve 49 in the standard way 13 meets. According to the above statements, in position a, the system is operated as a NH ₃ generator. In position b, the use of the RGS 1 in a prolonged fat phase with H ₂ / CO generation for the regeneration of the diesel particulate filter 31 (DPF regeneration) used. In setting c, the use of the engine exhaust gas to heat up the AGC 23 allows. Finally, at setting d, the burner exhaust gas is passed over the auxiliary heating heat exchanger. Depending on the design of said valve, the burner exhaust gas via the AGC 23 and take an optional small diesel particulate filter or direct it via the gas path into the main exhaust tract in front of the diesel particulate filter.

In addition to the described embodiments of the invention, within the RGS 1 a particle filter can be installed, which makes it possible to filter the particles from the burner exhaust gas. The cleaning or regeneration of the particulate filter, which then in the RGS 1 is provided by the hot gas, which is the standard way 13 is achieved. The particle filter also filters the particles that are in the fat phase in standard operation of the RGS 1 be formed.

Furthermore, the heat element 9 be operated so that it at the AGC 23 to a reduction of nitrogen oxides (NO _x ) comes. This can be achieved by two ways. For one, the heat element 9 (Burner) can be operated with an optimal fuel-air mixture (λ = 1) and thereby the AGC can greatly reduce the NO _x , CO and HC emissions via a 3-way functionality. On the other hand, the burner can be operated for the most part lean and the AGC stores the nitrogen oxides. To regenerate the memory then the burner (heat element 9 ) are briefly operated fat (λ <1).

Claims (23)

Reducing agent-generating system of an exhaust system of a motor vehicle, comprising a heat element which generates heat necessary for the operation of the system, characterized by a heat coupling element ( 55 ), which selects the heat or a portion thereof to at least one non-system device ( 59 ) of the motor vehicle. System according to claim 1, characterized in that the heating element is a heating element delivering hot gas ( 9 ) is trained. System according to one of the preceding claims, characterized in that the heat coupling element ( 55 ) a gas flow path ( 61 ) for the hot gas. System according to one of the preceding claims, characterized in that the non-system device ( 59 ) is an interior heating of a passenger compartment of the motor vehicle. System according to one of the preceding claims, characterized in that the non-system device ( 59 ) an internal combustion engine ( 27 ) of the motor vehicle. System according to one of the preceding claims, characterized in that the gas flow path ( 61 ) of the heat coupling element ( 55 ) with a heat exchanger ( 37 ), in particular a stationary heating heat exchanger, a cooling water circuit ( 41 ) of the motor vehicle is connectable. System according to one of the preceding claims, characterized in that the cooling water circuit ( 41 ) has a heating heat exchanger for heating the passenger compartment. System according to one of the preceding claims, characterized in that in the gas flow path ( 61 ) at least one shut-off element ( 17 ) is arranged. System according to one of the preceding claims, characterized in that the shut-off element ( 17 ) a metered adjustable shut-off element ( 17 ). System according to one of the preceding claims, characterized in that the heat element ( 9 ) is designed as a starting burner which generates the heat necessary for the operation of the system, in particular in the starting phase of the internal combustion engine. System according to one of the preceding claims, characterized in that it is a thermal plasma generating unit, preferably a plasmatron ( 7 ), a catalytic component ( 21 ) and an ammonia generator unit ( 23 ) having. System according to one of the preceding claims, characterized in that the hot gas or a portion thereof between the Plasmatron ( 7 ) and the catalytic component ( 21 ) for the supply to the non-system facility ( 59 ) is decoupled. System according to one of the preceding claims, characterized in that the hot gas or a portion thereof between the catalytic component ( 21 ) and the ammonia generator unit ( 23 ) for the supply to the non-system facility ( 59 ) is decoupled. System according to one of the preceding claims, characterized in that the heat exchanger ( 37 ) incoming hot gas into the system by means of a return ( 39 ) is returned. System according to one of the preceding claims, characterized in that the heat exchanger ( 37 ) Hot gas is fed into the exhaust system of the motor vehicle. Method for operating a reducing agent generating System of an exhaust system of a motor vehicle, with a heating element, that for the Operation of the system necessary heat generated, characterized in that the of the heat element generated heat or a proportion of it also to heat at least one non-system Device of the motor vehicle is used. Method according to claim 16, characterized in that that the heat generated or a portion thereof for the operation of a parking heater is used. Method according to one of the preceding claims, characterized in that the auxiliary heater is a passenger compartment and / or an internal combustion engine of the motor vehicle heats. Method according to one of the preceding claims, characterized characterized in that the heat of the heating element or a portion thereof, successive in time, either for generating the Reducing agent or for heating purposes of the non-system device is being used. Method according to one of the preceding claims, characterized characterized in that the heat of the heating element or a portion thereof at the same time for generating the Redukti onsmittels and is used for heating purposes of the non-system device. Method according to one of the preceding claims, characterized characterized in that the heat element generated heat especially before the starting phase of the internal combustion engine as heating the Internal combustion engine and / or as heating of the passenger compartment of the motor vehicle is being used. Motor vehicle with a reducing agent generating System according to one or more of the preceding claims. Use of a heat element of a reducing agent also generating system of an exhaust system of a motor vehicle for the purpose of heating at least one non-system device of the motor vehicle.