WO2007054485A1 - The use of a reduction agent generating system, in particular as auxiliary heating - Google Patents

Abstract

The invention relates to a reduction agent generating system of an exhaust system of a motor vehicle, comprising a heat element, which generates heat that is necessary for operating the system. A heat coupling element (55) is provided, optionally conducting the heat or parts thereof to at least one device (59) of the motor vehicle that is not part of the system.

Description

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

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

State of the art

In automotive technology, devices for selective catalytic reduction (SCR) are known in order to remove nitrogen oxides (NO _x ) in oxygen-containing exhaust gases and to reduce 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 of the invention

Because of the reducing agent generating system of the present invention, existing components can be used cost-effectively and / or to increase a variety of uses in a dual function in which the heat element of the reducing agent generating system (hereinafter called system) is also used to conduct heat to at least one non-system device. For this purpose, a heat coupling element is provided, which selectively supplies the heat generated by means of the heat element either to the components which generate the reducing agent, or at least to a system-foreign device. It is also conceivable that the heat is delivered to both assemblies at the same time. Accordingly, the heating element is used for a further purpose, namely heating of system-external devices of the vehicle.

According to a development of the invention it is provided that the heat element is designed as a hot gas delivering heat element. The hot gas, which preferably originates from a burner, is therefore supplied via the heat coupling element of the system-foreign device, if this mode is desired. Accordingly, the word "selectable" mentioned in claim 1 means that a switchover possibility exists to supply the heat only when necessary by means of the heat coupling element of the system-foreign device.

Furthermore, it is advantageous if the heat coupling element has a gas flow path for the hot gas. Accordingly, when the supply of heat to the non-system device is desired, the hot gas is introduced into the gas flow path and thereby reaches the point of use.

In particular, an interior heating of a passenger compartment of the motor vehicle is considered as a system-external device. Additive- Lich or alternatively, it may be provided that the system-foreign device is an internal combustion engine of the motor vehicle. Consequently, the passenger compartment of the motor vehicle and / or the internal combustion engine of the motor vehicle can be heated with the heat of the heating element. This is particularly advantageous before the starting phase of the internal combustion engine, since a warm start of the engine, especially in winter, this considerably protects and can reduce the environmental impact and fuel consumption.

A development of the invention provides that the gas flow path of 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 selectively supplied to the auxiliary heating heat exchanger, whereby the cooling water of the motor vehicle is heated. This has the consequence that on the one hand, the internal combustion engine is heated and on the other hand, a heating heat exchanger can be operated, which is located in the cooling water circuit and therefore heat is provided for heating the passenger compartment. This increases the comfort of the occupants and the safety of the traffic, as the panes of the passenger compartment do not fog up, the driver does not have a prolonged reaction time at low temperatures and the driver does not have to wear thick clothing when driving.

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

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

Advantageous developments of the method emerge from the claims.

Furthermore, the invention relates to a motor vehicle with a reducing agent-generating system according to the preceding embodiments.

Finally, the invention relates to the use of a heat element of a reducing agent-generating system of a Abgas- anläge a motor vehicle for the purpose of heating at least one non-system device of the motor vehicle.

The invention will be explained in more detail below with reference to the drawings. Show it

Figure 1 is a schematic representation of the reducing agent-generating system

Figure 2 to Figure 5 are schematic representations of the reduction-generating system according to further embodiments of the invention.

FIG. 1 shows a reducing agent-generating system (RGS) 1 assigned to a vehicle, not shown, which has two inputs 3 and 5. 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 connected to a branch 11, which splits the path into two parts, namely in a standard way 13 and a parking heater 15th In Standardweg 13 is a shut-off 17, which is designed as a 2-2 valve. This is followed by another branch 19, at which the auxiliary heating path 15 again meets the standard route 13 after passing through a heat exchanger 37. This is followed by a catalytic component 21, which is linked to an ammonia generator unit 23, hereinafter referred to as AGC for Ammonia Generating Catalyst or simply as NH ₃ generator.

Furthermore, an exhaust system 25 is present, which is connected to an internal combustion engine 27 of the motor vehicle, which is connected to a diesel oxidation catalyst (DOC) 29. 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 to reduce them to nitrogen and water. As the reducing agent, ammonia generated by the ammonia generator unit (AGC) 23 is used. Between the DPF 31 and the SCR device 33, a junction 35 is provided which links the AGC 23 to the exhaust system 25 in the region between the diesel particulate filter 31 and the SCR device 33.

Following the parking heater path 15, the heat exchanger 37 is connected to the branch 11. This can be formed for example as a parking heater heat exchanger. Coming from this heat exchanger 37, a return 39 is provided, which is linked to the branch 19. There, the parking heater 15 again connects to the standard way 13. The heat exchanger 37 is connectable / connected to a cooling water circuit 41 of the motor vehicle.

When the internal combustion engine 27 is running, diesel fuel and air / exhaust gas are fed to the inputs 3, 5 during operation of the reducing agent-generating system (RGS). In Plasmatron 7 with integrated heat element 9 nitrogen oxides are generated in a lean phase. The gas mixture is heated. After the exit meets the heated gas mixture, the so-called hot gas, on the branch 11 and then in the standard way 13 on the shut-off 17. The standard operation, the shut-off element 17 is open. The hot gas is passed through the catalytic component 21. This converts fuel metered into the area of the plasmatron 7 during a fatty phase into a hydrogen and CO-containing gas mixture. Thereafter, the hot gas is passed through the AGC 23 where the ammonia necessary to operate the SCR device 33 is generated. The catalytic component 21 required for operating a temperature of 250 ⁰ C - 800 ⁰ C, preferably 650 ° C, while the operation of the AGC 23 at a temperature of 150 ⁰ C - 350 ° C, preferably 250 ° C is necessary. The heat required for this supplies the heated by the heating element 9 hot gas. The ammonia is passed via the junction 35 in the exhaust system 25 and used in the SCR device 33 for the exhaust gas treatment.

Before starting the engine 27, the RGS 1 is not needed in the above manner. According to the invention, however, the still put into operation heat element 9 can be used, ie the heat element 9 provides hot gas. The heat of the hot gas can be used in particular for non-use of the RGS 1 for heating system-external devices 59 of the motor vehicle, namely the internal combustion engine 27 and / or a passenger compartment of the motor vehicle, which is not shown in FIG. For this purpose, a heat coupling element 55, which diverts the heat into a usable form for this purpose, is used. This includes according to Figure 1, the branch 11, an inlet 57 of the parking heater 15, the heat exchanger 37, the return 39, the junction 19 and the shut-off 17. When the shut-off element 17 is closed, the hot gas via the guide 57 in the heat exchanger 37 headed. In the heat exchanger 37, a heat exchange with the cooling water of a cooling water circuit 41 of the internal combustion engine 27 takes place. The heat exchanger 37 forms in particular a stationary heating heat exchanger, ie he serves the heating of non-system devices 59 of the particular non-moving motor vehicle. The heated cooling water is used for heating (preheating) of the internal combustion engine 27. 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 returned to the RGS 1, namely via the return 39 into the branch 19, and finally enters the exhaust system of the internal combustion engine 27. Accordingly, the heat coupling element 55 has a gas flow path 61 for the hot gas.

The core of the invention is accordingly to use the starting burner of the RGS 1 as a heater. As a result, for example, the internal combustion engine 27 preheated and / or the passenger compartment of the motor vehicle can be preheated. Accordingly, if the start burner of the RGS 1 (ammonia generator) is not needed, ie in particular before a start of the internal combustion engine, then this 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 standard route 13), NH ₃ is prepared from the starting materials NO and H ₂ . NO is generated in a lean phase (in air or exhaust mode with λ> 1) in a Plasmatron 7 in air. These nitrogen oxides then flow through the catalytic partial oxidation state (cPOx) and are in the downstream of the catalytic unit (NH ₃ - Producer). In a second phase of operation subsequent to the lean phase, the fat phase (0.33 <λ <1), liquid fuel is metered into an evaporation and mixture-forming zone in the area of the plasmatron 7 and in the cPOx stage (catalytic partial oxidation). converted to a Hb 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 this case, in the temperature range between 150 ⁰ C and 450 ⁰ C, the catalysts of titanium dioxide (TiO 2) and vanadium pentoxide (V2O5) to set the nitrogen oxides with the produced ammonia 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 NH3 requirement, the parking heater 15 is no longer used, but the standard way 13, so that the system can be operated again as NH3 generator. It is also a mixed operation conceivable, so both NH ₃ production and the heating system-independent devices 59th

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

FIG. 3 also largely corresponds to the arrangement in FIG. 1, so that a detailed description is dispensed with. It is again true that the reference numerals correspond to those of the description of Figure 1. One difference is that the branch 11 is provided after the catalytic component 21. This is followed, as in Figure 1 in Standardweg 13 a shut-off 17 and then the branch 19, where the auxiliary heating path 15 again meets the standard path 13. In this case, the catalytic component 21 is flowed through in any case (ie also in the auxiliary heating mode) by the hot gas and is operable. This also results in a strong reduction of HC and CO emissions.

FIG. 4 likewise largely resembles FIG. 1. Here too, the reference numbers of the description of FIG. 1 correspond to those of FIG. 4. A difference from FIG. 1 is that in the auxiliary heating path 15 the hot gas no longer enters the standard path 13 after passing through the heat exchanger 37 is returned before the ammonia generator unit 23, but is introduced directly into the exhaust system 25 in front of the SCR device 33. In this case, two valves 45 and 47 (in particular two 2-2 valves) are provided. The valve 45 is located between the AGC 23 and the confluence 35 in the standard path 13. The valve 47 is provided in the stationary heating path 15 between the heat exchanger 37 and a junction 43 which is located in the exhaust system 25 in front of the SCR device 33. Depending on the setting of the valves 45 and 47, the hot gas can be conducted either through the standard path 13 and / or through the auxiliary heating path 15.

FIG. 5 shows a further possible arrangement of the invention. Again, the reference numerals used here correspond to those of the description of FIG. 1, so that a detailed description is given. is omitted. Notwithstanding here is a valve 49, not shown in detail, which is arranged between the catalytic component 21 and the AGC 23. From the valve 49, a connection 51 additionally goes to the exhaust system 25 (between the internal combustion engine 27 and the catalytic converter 29) and the return 39 of the auxiliary heating system 15 is likewise coupled to the valve 49. The valve 49 may be formed as a 4-4 valve, wherein intermediate positions may be possible, as is possible for example in a linear valve. Depending on the setting, which are referred to below as settings a, b, c, d, the default path 13 is run through with setting a. With setting b, the catalytic component 21 is coupled to the exhaust system 25 via the connection 51. The hot gas is in this case passed directly via the catalytic component 21 and the connection 51 into the exhaust system 25. With setting c, the exhaust system 25 is connected to the AGC 23 via the connection 51. The exhaust gas is conducted from the engine 27 via the connection 51 into the AGC 23. With setting d, the auxiliary heating path 15 is traversed, wherein the hot gas is conducted around the catalytic component 21 in this arrangement and impinges on the standard path 13 at the valve 49. According to the above embodiments _ß Generating Sets is operated in a position the system as NH. 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) is used. In setting c, it is possible to use the engine exhaust to heat the AGC 23. Finally, at setting d, the burner exhaust gas is passed over the auxiliary heating heat exchanger. Depending on the design of the valve mentioned above, the burner exhaust gas can be taken via the AGC 23 and an optional small diesel particulate filter or can be routed directly via the gas path to 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 particulate filter can be installed, which it allows to filter the particles from the burner exhaust gas. The cleaning or regeneration of the particulate filter, which is then provided in the RGS 1, can be achieved by the hot gas which is conducted via the standard route 13. The particle filter also filters the particles that are formed in the fat phase in standard operation of the RGS 1.

Furthermore, the heating element 9 can be operated in such a way that the nitrogen oxides (NO _x ) are reduced at the AGC 23. This can be achieved by two ways. On the one hand, the heat element 9 (burner) can be operated with an optimum fuel-air mixture (λ = 1), and the AGC can greatly reduce the NO _x , CO and HC emissions via a 3-way functionality. On the other hand, most of the burner can be run lean and the AGC stores the nitrogen oxides. To regenerate the memory, the burner (heat element 9) must then be briefly operated in fat (λ <1).

Claims

R. 312912patents claims A reductant generating system of an exhaust system of a motor vehicle, comprising a heat element that generates heat necessary for operation of the system, characterized by a heat coupling element (55) that selectively conducts heat or a portion thereof to at least one non-system device (59) of the motor vehicle , 2. System according to claim 1, characterized in that the heat element is designed as a hot gas supplying heat element (9). 3. System according to one of the preceding claims, characterized in that the heat coupling element (55) has a gas flow path (61) for the hot gas. 4. System according to any 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. 5. System according to any one of the preceding claims, characterized in that the non-system device (59) is an internal combustion engine (27) of the motor vehicle. 6. System according to any 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. 7. System according to any one of the preceding claims, characterized in that the cooling water circuit (41) has a heating heat exchanger for heating the passenger compartment. 8. System according to any one of the preceding claims, characterized in that in the gas flow path (61) at least one shut-off element (17) is arranged. 9. System according to any one of the preceding claims, characterized in that the shut-off element (17) is a metered adjustable shut-off element (17). 10. System according to any 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. 11. System according to any one of the preceding claims, characterized in that it comprises a thermal plasma generating unit, preferably a plasmatron (7), a catalytic component (21) and an ammonia generator unit (23). 12. System according to any 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 device (59) is coupled out. 13. 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 Producer unit (23) for feeding to the non-system device (59) is coupled out. 14. System according to any one of the preceding claims, characterized in that the hot gas from the heat exchanger (37) coming back into the system by means of a return (39) is returned. 15. System according to any one of the preceding claims, characterized in that the from the heat exchanger (37) coming hot gas is fed into the exhaust system of the motor vehicle. 16. A method for operating a reducing agent generating system of an exhaust system of a motor vehicle, with a Heat element that generates necessary for the operation of the system heat, characterized in that the heat generated by the heat element or a portion thereof is also used to heat at least one non-system device of the motor vehicle. 17. The method according to claim 16, characterized in that the heat generated or a portion thereof is used for the operation of a heater. 18. The method according to any one of the preceding claims, characterized in that the auxiliary heater heats a passenger compartment and / or an internal combustion engine of the motor vehicle. 19. The method according to any one of the preceding claims, characterized in that the heat of the heat element or a portion thereof in succession time either to Generating the reducing agent or is used for heating purposes of the non-system device. 20. The method according to any one of the preceding claims, character- ized in that the heat of the heat element or a portion thereof is used simultaneously for generating the reducing agent and for heating purposes of the non-system device. 21. The method according to any one of the preceding claims, characterized in that the heat generated by the heat element is used in particular before the start phase of the internal combustion engine as heating of the internal combustion engine and / or as heating of the passenger compartment of the motor vehicle. 22 motor vehicle with a reducing agent generating system according to one or more of the preceding claims. 23. Use of a heat element of a reducing agent 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.