DE102007042836A1 - Device for exhaust-gas aftertreatment of exhaust gas stream of motor vehicle by liquid releasing ammonia, has storage container for storage of liquid, and tempering unit is provided for tempering of liquid - Google Patents

Abstract

The device (1) has a storage container (35) for storage of a liquid (19). A tempering unit is provided for tempering of the liquid. The tempering unit is assigned to an air conditioning installation circuit of a motor vehicle (3) for cooling the liquid. The storage container is attached to a cooling circuit (31). The storage container is assigned to a heat exchanger (33) connected in the cooling circuit.

Description

The The invention relates to a device for exhaust gas aftertreatment Exhaust gas flow of a motor vehicle by means of an ammonia releasing Liquid, with a storage tank for storage the liquid.

In order to reduce NOx emissions from internal combustion engines, in particular diesel engines, from motor vehicles, it is known to use a so-called SCR catalytic converter (selective catalytic reduction or selective catalytic reduction) in an exhaust gas flow generated by the internal combustion engine. SCR catalysts convert existing NOx emissions into the exhaust stream in the presence of ammonia. In order to provide the necessary ammonia in the exhaust gas stream, it is known to incorporate into it an ammonia-releasing liquid, for example an aqueous urea solution. For example, to prevent freezing of this solution, it is known to heat them. An overview can be found in the publication "Perspectives of mobile SCR technology" by Dr. Eberhard Jacob, 15th Aachener Kolloquium Fahrzeug- und Motorentechnik, available at: http://www.emitec.com/download/library/de/061030_Aachen_SCR_deutsch final.pdf. Further, from the publication "Heating Concepts for AdBlue Tanks: Problems and Simulation" by Dr.-Ing. Habil. Stefan from the Wiesche, VDI Reports No. 1967, 2006, pages 895-906 as well as from he EP 1 698 769 A2 known to provide a powered with a return of engine cooling water coil.

Of the Invention is based on the object, an improved device to provide the exhaust aftertreatment, in particular an improved temperature allow the ammonia releasing liquid.

The Task is with a device for exhaust aftertreatment Exhaust gas flow of a motor vehicle by means of an ammonia-releasing liquid, with a storage container for storing the liquid, wherein a tempering device for tempering the liquid is provided, solved in that the temperature control for Cooling the liquid an air conditioning circuit is assigned to the motor vehicle. The ammonia releasing liquid For example, a eutectic solution of 32.5% urea in Have water whose freezing point is -11 ° C.

Advantageous can by means of an assignment to the cooling circuit, the liquid are heated, so that, for example, prevent freezing is. Advantageously, the heating of the liquid also to a desired temperature level at which a particularly good emission control results are brought. This is also advantageous with other ammonia-releasing liquids, for example, ammonium formate, denoxium-30, methanamide and / or ammonium carbamate possible. By means of tempering or heating The liquid can be an optimal release of ammonia for the reactant and product selective catalyst respectively SCR catalyst can be enabled. Furthermore, through the optimal tempering a formation of solid residues, for example, caused by a delayed evaporation, be prevented as best as possible. Advantageously, it is possible if an additional electric heater for temperature control of Liquid is provided for it needed to save electrical energy. Advantageously, by means of the assignment from a refrigerant of the air conditioning circuit heat and / or cold transferred to the liquid become. Advantageously, for example, overheating the liquid can be avoided.

at a preferred embodiment of the device provided that the reservoir the cooling circuit assigned. Advantageously, the entire reservoir and thus all the liquid in it be tempered.

at a further preferred embodiment of the device is provided that the reservoir into the cooling circuit associated first heat exchanger connected. Advantageous can heat over the first heat exchanger from a cooling liquid of the cooling circuit transferred to the reservoir and thus to the liquid become.

at a further preferred embodiment of the device It is envisaged that the tempering a in the air conditioning circuit having switched second heat exchanger. Advantageous can heat by means of the second heat exchanger and / or cold transferred to the liquid become.

at a further preferred embodiment of the device is provided that the second heat exchanger downstream of the reservoir and a metering device for dosing in the liquid is connected upstream of the exhaust stream. By means of the second heat exchanger can from the heated reservoir to the metering device flowing liquid to be cooled.

In a further preferred embodiment of the device, it is provided that the second heat exchanger is an expansion valve downstream of the air conditioning circuit.

By the relaxation of the guided in the air conditioning circuit Refrigerant, the downstream second heat exchanger and thus cooling the liquid flowing therein become.

at a further preferred embodiment of the device is provided that the cooling circuit one of the first Heat exchanger upstream has additional heating. through The additional heater may additionally be in the direction of the first Heat exchanger, guided in the cooling circuit Coolant additionally heated become.

at a further preferred embodiment of the device is provided that the reservoir an electrical Additional heating is connected downstream. Advantageously, the of the reservoir flowing in the direction of the metering liquid additionally heated electrically.

The Task is also with a motor vehicle with a solved before device for exhaust aftertreatment.

Further Advantages, features and details emerge from the following Description, in which with reference to the drawing an embodiment is described in detail. Same, similar and / or functionally identical parts are provided with the same reference numerals.

It demonstrate:

1 a schematic view of an exhaust system of a motor vehicle with a device for the exhaust aftertreatment of a guided in the exhaust system exhaust stream; and

2 a detailed view of in 1 shown device for exhaust aftertreatment, coupled with a cooling circuit and an air conditioning circuit of the motor vehicle.

1 shows a device 1 a motor vehicle 3 with an exhaust system 5 , In the exhaust system 5 is a means of the device 1 aftertreatable exhaust gas stream 7 guided. The flow direction of the exhaust gas flow 7 is by means of an arrow 9 indicated.

The exhaust system 5 is an internal combustion engine 11 downstream of the exhaust stream 7 generated. By means of a combustion engine 11 downstream diesel particulate filter 13 which may advantageously have a coating may be in the exhaust stream 7 existing particles, such as soot particles, are filtered out. The diesel particulate filter 13 is a temperature sensor 15 for measuring a temperature of the exhaust system 5 guided exhaust gas flow 7 downstream. Downstream of the temperature sensor 15 is one in the exhaust system 5 or in the exhaust gas stream 7 opening metering valve 17 for dosing an ammonia-releasing liquid 19 arranged. The liquid may be, for example, an aqueous solution containing urea, for example a eutectic solution of 32.5% urea in water. After metering in the liquid 19 can this, a corresponding means of the temperature sensor 15 assuming determined temperature, release ammonia. To a very uniform evaporation and / or distribution of the liquid or mixing of the liquid with the exhaust stream 7 to allow, is the metering valve 17 a mixer 21 , For example, a static mixer, downstream. The by means of the metering valve 17 and the mixer 21 produced mixture can be a downstream SCR catalyst 23 supplied, for example, an SCR catalyst based on iron zeolite and / or with other catalytically active substances. By means of the implementation of the liquid 19 can the exhaust gas flow 7 H ₂ O, NH ₃ and HNCO molecules are added, it is possible that the SCR catalyst 23 is designed for a two-stage formation of ammonia, wherein first evaporates the water, carried out a urea thermolysis and isocyanic acid hydrolysis. By means of the so in the exhaust stream 7 introduced ammonia can in the exhaust gas stream 7 NOx emissions are reduced or disproportionated to nitrogen.

The by means of the SCR catalyst 23 post-treated exhaust gas flow 7 is downstream on a sensor 25 for measuring a NOx and / or NH ₃ concentration of the exhaust gas stream 7 past. Downstream of the SCR catalyst 23 indicates the exhaust system 5 a downstream barrier catalyst 27 on. The barrier catalyst 27 serves to possibly convert excess amounts of ammonia and thus to prevent unwanted ammonia slip, which can be accepted that it again arise in small quantities NOx emissions. Furthermore, it is conceivable that the blocking catalyst 27 has a certain storage capacity for ammonia. The barrier catalyst 27 is a conventional silencer 29 downstream. Downstream of the muffler 29 the exhaust system opens 5 towards the environment.

The internal combustion engine 11 can by means of a cooling circuit 31 be cooled. The cooling circuit 31 is via a first heat exchanger a reservoir 35 for storing the liquid 19 assigned. Advantageously, the reservoir 35 by means of the internal combustion engine 11 of the force vehicle 3 generated waste heat to be tempered or heated.

The storage tank 35 may be a conveyor for conveying the liquid 19 have or upstream of this and is via a flow line 37 and a return line 39 the metering valve 17 assigned. Downstream of the reservoir 35 can the flow line 37 an additional electric heater 41 for additional heating of the liquid 19 exhibit. This can, for example, during a warm-up phase of the internal combustion engine 11 make sense.

By means of control lines 43 is the device 1 for the aftertreatment of the exhaust system 5 guided exhaust gas flow 7 a central control unit 45 , For example, an engine control unit of the internal combustion engine 11 , assigned. The control unit 45 may have suitable control and regulating algorithms, for example, to regulate a so-called feed ratio. Under feed ratio can in relation to a raw NOx emission of the exhaust stream 7 Relative or necessary injection quantity of the liquid 19 be understood. From an optimal feed ratio can at the highest possible rate of conversion in the exhaust stream 7 contained NOx emissions and a minimum, the SCR catalyst 23 leaving unreacted residual amount of ammonia (minimal ammonia slip).

2 shows a detail view of in 1 shown device 1 for the aftertreatment of an exhaust gas stream 7 a motor vehicle 3 , In difference is the device 1 in addition an air conditioning circuit 47 of the motor vehicle 3 assigned. The air conditioning circuit 47 has a second heat exchanger 49 on, with the assignment of the air conditioning circuit 47 by means of the second heat exchanger 49 he follows. This is the second heat exchanger 49 in the supply line 37 connected. The second heat exchanger 49 can be used for cooling in the flow line 37 guided liquid 19 serve. This is the second heat exchanger 49 an expansion valve 51 of the air conditioning circuit 47 downstream. The second heat exchanger 49 So can as an additional evaporator of the air conditioning circuit 47 Act. Optionally, the expansion valve 51 be controllable, so that the cooling is independent of the operation of the rest of the air conditioning circuit 47 can be done.

The rest of the air conditioning circuit 47 has the usual components, a compressor 53 , a capacitor 55 , Another, optionally also controllable expansion valve 57 and a downstream of this evaporator 59 on. The expansion valve 51 and the downstream second heat exchanger 49 are connected in parallel to the further expansion valve 57 and the evaporator 59 , Advantageously, by means of the air conditioning circuit 47 or of the second heat exchanger 49 of the air conditioning circuit 47 one possibly by means of the first heat exchanger 33 transferred too high temperature of the liquid 19 in the supply line 37 , ie before reaching the metering valve 17 to be cooled again.

The first heat exchanger 33 can be in a small cooling circuit 61 the cooling circuit 31 of the internal combustion engine 3 be switched. For this purpose, it is conceivable, the small cooling circuit 61 around the first heat exchanger 33 having parallel branch 63 to complete. The parallel branch 63 can one by means of a regulator 65 controlled control valve 67 exhibit. To control a reservoir 35 by means of the first heat exchanger 33 supplied amount of heat or for adjusting a temperature of the reservoir 35 can the regulator 65 a temperature sensor 69 be assigned. It is possible, for example, by means of the regulator 65 and the control valve 67 upon reaching a limit temperature the parallel branch 63 of the small cooling circuit 61 of the cooling circuit 31 of the internal combustion engine 11 shut off, so that no further heat transfer occurs.

In summary, via the second heat exchanger 49 who is in the supply line 37 is arranged, a cooling of the liquid 19 respectively. Additionally or alternatively, it is conceivable for cooling the storage container 35 the second heat exchanger 49 to assign this directly. The cooling power required for cooling can advantageously by means of an already existing air conditioning or air conditioning circuit 47 of the motor vehicle 3 respectively.

A heating of the reservoir 35 can over the into the cooler cycle 31 switched first heat exchanger 33 take place, by means of the internal combustion engine 11 heated coolant and / or by means of an additional heater 71 of the small cooling circuit 61 heated coolant done. Advantageously, the heating by means of the first heat exchanger 33 in addition to a possibly existing electric heater 41 respectively.

It is advantageous, for example by means of the control unit 45 , a regulation of the cooling and heating or temperature control of the liquid 19 possible in a desired temperature window.

1

contraption

3

motor vehicle

5

exhaust system

7

exhaust gas flow

9

arrow

11

internal combustion engine

13

Diesel Particulate Filter

15

temperature sensor

17

metering valve

19

ammonia releasing fluid

21

mixer

23

SCR catalyst

25

sensor

27

blocking catalytic converter

29

silencer

31

Cooling circuit

33

first heat exchangers

35

reservoir

37

supply line

39

Return line

41

heater

43

control lines

45

central control unit

47

Air conditioning circuit

49

second heat exchangers

51

expansion valve

53

compressor

55

capacitor

57

expansion valve

59

Evaporator

61

smaller Cooling circuit

63

parallel branch

65

regulator

67

control valve

69

temperature sensor

71

additional heating

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 1698769 A2 [0002]

Cited non-patent literature

• - http://www.emitec.com/download/library/de/061030_Aachen_SCR_englisch final.pdf. [0002]
• - "Heating Concepts for AdBlue Tanks: Problems and Simulation" by Dr.-Ing. Habil. Stefan from the Wiesche, VDI Reports No. 1967, 2006, pages 895-906 [0002]

Claims (10)

Contraption ( 1 ) for the exhaust aftertreatment of an exhaust gas stream ( 7 ) of a motor vehicle ( 3 ) by means of an ammonia-releasing liquid ( 19 ), with a storage container ( 35 ) for storing the liquid ( 19 ), wherein a tempering device for tempering the liquid ( 19 ) is provided, characterized in that the temperature control device for cooling the liquid ( 19 ) an air conditioning circuit ( 47 ) of the motor vehicle ( 3 ) assigned. Device according to one of the preceding claims, characterized in that the storage container ( 35 ) the cooling circuit ( 31 ) assigned. Device according to one of the preceding claims, characterized in that the storage container ( 35 ) one in the cooling circuit ( 31 ) connected first heat exchanger ( 33 ) assigned. Device according to one of the preceding claims, characterized in that the tempering a in the air conditioning circuit ( 47 ) connected second heat exchanger ( 49 ) having. Device according to the preceding claim, characterized in that the second heat exchanger ( 49 ) the reservoir ( 35 ) and a dosing device ( 17 ) for dosing the liquid ( 19 ) in the exhaust stream ( 7 ) is connected upstream. Device according to one of claims 4 or 5, characterized in that the second heat exchanger ( 49 ) an expansion valve ( 51 ) of the air conditioning circuit ( 47 ) is connected downstream. Device according to one of claims 3 to 6, characterized in that the cooling circuit ( 31 ) a the first heat exchanger ( 33 ) upstream auxiliary heating ( 71 ) having. Device according to one of the preceding claims, characterized in that the storage container ( 35 ) an electric heater ( 41 ) is connected downstream. Device according to one of the preceding claims, characterized in that the temperature control device for heating the liquid ( 19 ) a cooling circuit ( 31 ) of the motor vehicle ( 3 ) assigned. Motor vehicle ( 3 ) with a device ( 1 ) for the exhaust aftertreatment of an exhaust gas stream ( 7 ) according to any one of the preceding claims.