DE102008006630A1 - Exhaust gas aftertreatment device for exhaust gas flow of diesel engine of motor vehicle, has temperature maintaining device assigned to auxiliary heater of combustion engine by valve arrangement - Google Patents

Abstract

The device (1) has a storage container (35) for storage of a liquid, and a temperature maintaining device (47) provided for maintaining temperature of a liquid. The temperature maintaining device is assigned to an auxiliary heater (49) of a combustion engine (11) by a valve arrangement (77). The temperature maintaining device for cooling of the liquid is assigned to an air conditioning installation circuit (51) of a motor vehicle (3). The auxiliary heater is uncoupled from the temperature maintaining device and/or the combustion engine by the valve arrangement.

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 gives the publication "Perspectives of Mobile SCR Technology" by Dr. Eberhard Jacob, 15th Aachen Colloquium Automotive and Engine Technology, 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. The unpublished application of the same applicant with the file number DE 10 2007 042 836.9 shows a device for exhaust aftertreatment of an exhaust gas stream of a motor vehicle by means of a liquid releasing ammonia, wherein a tempering device for cooling the liquid is associated with an air conditioning circuit of the motor vehicle.

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 an internal combustion engine of a motor vehicle by means of an ammonia-releasing liquid, with a reservoir for storing the liquid, wherein a tempering device for Tempering the liquid is provided, thereby solved that the temperature control device to a heater of the internal combustion engine assigned. The heater may be a fuel-powered one Zuheizgerät act, as for example for Parking heaters can be used. Advantageously, the heater on known manner a cooling circuit, preferably a small cooling circuit, the engine quickly heat up, for example, after a cold start to thereby on the one hand, the internal combustion engine of the motor vehicle on quickly to bring an operating temperature and on the other hand, a heating power to increase a cabin heating of the motor vehicle. Of the Heater has a heat exchanger for transfer of heat on the cooling circuit of the internal combustion engine on. Advantageously, by means of the assignment of the temperature control to the heater also stored in the reservoir Fluid faster to a desired target temperature to be heated. Can be advantageous compared to a Electric heater of the reservoir a multiple on heat output, for example up to 10 times, for heating of the reservoir are provided.

at an embodiment of the devices is provided that the tempering device for cooling the liquid associated with an air conditioning circuit of the motor vehicle. It is advantageous by means of the assignment to the air conditioning circuit additionally possible, the liquid as needed, for example, in the event of impending overheating, to cool. The ammonia-releasing liquid may be, for example have a eutectic solution of 32.5% urea in 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, be brought. This is also beneficial with other ammonia releasing fluids, 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 or SCR catalyst be enabled. Furthermore, by the optimal temperature control a formation of solid residues, for example caused by a delayed evaporation, best possible be prevented. Advantageously, it is possible, if one additional electric heater for temperature control of the liquid is provided for this required electrical energy save. Advantageously, by means of the assignment of a refrigerant of the air conditioning circuit heat and / or cold be transferred to the liquid. Advantageous This can, for example, overheat the liquid be avoided.

In a further embodiment of the device is provided that the Temperiervor direction by means of a valve assembly, the engine is assigned. Advantageously, by means of the valve arrangement, the temperature control device directly to the internal combustion engine, for example, the small cooling circuit, are assigned. Advantageously, the valve arrangement can be designed so that in this case the heater is bypassed. This state can be controlled, for example, after reaching the operating temperature of the internal combustion engine

at a further embodiment of the device provided that the heater by means of the valve assembly of the Tempering device and / or the internal combustion engine decoupled is. Advantageously, the heater, for example after reaching the operating temperature of the internal combustion engine and / or after reaching a desired temperature of the liquid not from a corresponding cooling medium be flowed through

at a further embodiment of the device provided that the temperature control device a second heat exchanger the air conditioning circuit is assigned. By means of the second heat exchanger The liquid may be advantageous for cooling heat be withdrawn.

at a further embodiment of the device provided that the second heat exchanger between a Evaporator and a compressor of the air conditioning circuit is switched. After the evaporator is advantageously the coolest temperature the air conditioning circuit, so that a particularly good cooling the liquid is possible. It is conceivable that second heat exchanger in series with the evaporator and the To switch compressor. However, it is also conceivable, the second heat exchanger switch into a bypass branch advantageous can a shut-off device, For example, a controllable valve, be provided to the second Heat exchanger as needed with a refrigerant of the air conditioning circuit. The control of a corresponding Volume flow of the bypass branch may depend on a required cooling capacity of the air conditioning system of the motor vehicle and / or for cooling the liquid of the storage container respectively.

at a further embodiment of the device provided that the tempering an electrically operable Has heating for heating the reservoir. By means of the electric heater can additionally warming the liquid of the reservoir. This can, for example, in a stationary state of the internal combustion engine take place, with the heater is turned off.

at a further embodiment of the device provided that the device on the tempering device acting central control unit for control and / or regulation a temperature of the stored in the reservoir Has liquid. The temperature can be controlled by means of a Control of at least one or more or all of the components the tempering take place.

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 another device for exhaust aftertreatment, wherein in contrast to the representation according to 1 the reservoir is associated with a heater 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 a pillar 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 initially the water evaporates, carried out a urea thermolysis and an 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 33 a storage container 35 for storing the liquid 19 assigned. Advantageously, the reservoir 35 by means of the internal combustion engine 11 of the motor 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 another device 100 for exhaust aftertreatment of the exhaust stream 7 of the motor vehicle 3 , The device 100 according to 2 has a tempering device 47 for temperature control in the reservoir 35 stored as well as in the supply line 37 and the return line 39 circulating liquid. The tempering device 47 has in particular the electric heater 41 , in contrast to the representation according to 1 the reservoir 35 directly assigned, a heater 49 of the internal combustion engine 11 and / or an air conditioning circuit 51 associated second heat exchanger 53 on. The air conditioning circuit 51 can be part of an air conditioner 55 for the realization of a cabin cooling of the motor vehicle 3 be. The air conditioning circuit 51 points next to the second heat exchanger 53 a compressor 57 , this downstream of a capacitor 59 , this downstream an expansion valve 61 and this downstream of an evaporator 63 on. The compressor 57 is the evaporator 63 downstream. Besides, the compressor is 57 by means of a bypass branch 65 the second heat exchanger 53 downstream. The air conditioning circuit can be traversed by a refrigerant that by means of the second heat exchanger 53 which is in the return line 39 withdrawing circulating liquid for cooling the same heat. This is the second heat exchanger 53 in the return line 39 switched, so it can be traversed by the liquid and the refrigerant. The drive is the compressor 57 the air conditioning 55 the internal combustion engine 11 assigned. For controlling the flow of the refrigerant through the bypass branch 65 and thus a cooling capacity of the second heat exchanger 53 can the evaporator 63 a valve 67 be downstream. The valve 67 branches in the direction of the compressor 57 and the second heat exchanger 53 and can convert a flow of refrigerant into controllable substreams towards the compressor 57 and heat exchangers 53 split.

The cooling circuit 31 of the internal combustion engine 11 is by means of a third heat exchanger 69 the heater 49 assigned. The first heat exchanger 33 of the storage container 35 is by means of a fourth heat exchanger 71 also the Zuheizer 49 assigned. About the heat exchangers 69 and 71 can the cooling circuit 31 of the internal combustion engine 11 and the reservoir 35 thermally coupled.

By means of a flow bypass line 73 and / or a return bypass line 75 can the first heat exchanger 33 of the storage container 35 directly to the cooling circuit 31 of the internal combustion engine 11 be assigned. By means of an optimal valve arrangement 77 can the cooling circuit 31 in the bypass lines 73 and 75 be branched. By means of the valve arrangement 77 it is possible to set any bypass partial flow, so that, for example, the third heat exchanger 69 only partially with a cooling medium of the cooling circuit of the 31 is flowed through, with a remaining part of the first heat exchanger 33 flows through. By means of the valve arrangement 77 it is also possible to use the cooling circuit 31 of the internal combustion engine 11 decouple completely so that the cooling medium is 100% through the third heat exchanger 69 flows. In this switching position of the valve assembly 77 results in a closed circuit between the first heat exchanger 33 and the fourth heat exchanger 71 , being inside the auxiliary heater 49 produced heat on the reservoir 35 is transferable. To drive this decoupled circuit, a pump shown in dashed lines 79 be provided. If the heater 49 itself has a heat exchanger function, for example, a heat transfer between the third heat exchanger 69 and the fourth heat exchanger 71 occur. Furthermore, it is conceivable that the heater 49 one the heat exchanger 69 and 71 connecting overflow line 81 having. The valve arrangement 77 may be connected in this case so that a flow of the cooling medium from the engine 11 coming first through the third heat exchanger 69 , through the overflow line 61 , through the heat exchanger 71 , through the first heat exchanger 33 and via the return bypass line 75 back to the combustion engine 11 results. The pump 79 is not necessary if a drive by means of a coolant pump of the internal combustion engine 11 he follows. Advantageously, by means of the auxiliary heater 49 the reservoir 35 as well as the internal combustion engine 11 equally heated.

To determine an actual temperature of the liquid in the reservoir 35 this can be a temperature sensor 83 be assigned. The means of the temperature sensor 83 detectable temperature can be from the central control unit 45 be read out. For simplicity, in 2 except for a control line between the temperature sensor 83 and the central control unit 45 no further control lines provided. The central control unit 45 can the tempering 47 the device 1 to control, for example, a temperature control of the reservoir 35 as well as in the lines 37 and 39 to realize circulating liquid.

The electric heater 41 is an electrical energy source 85 , For example, a vehicle battery of the motor vehicle 3 , assigned. To a circulation of the liquid in the supply line 37 and the return line 39 to supply the metering valve 17 To maintain, the supply line indicates 37 a conveyor 87 or a pump.

In summary, via the second heat exchanger 53 which is in the return line 39 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 53 to assign this directly. The cooling power required for cooling can advantageously by means of an already existing air conditioning or air conditioning circuit 51 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 the auxiliary heater 49 of the cooling circuit 31 , In particular a small cooling circuit, heated coolant take place. 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

tempering

49

Heaters

51

Air conditioning circuit

53

heat exchangers

55

air conditioning

57

compressor

59

capacitor

61

expansion valve

63

Evaporator

65

bypass branch

67

Valve

69

third heat exchangers

71

fourth heat exchangers

73

Forward-bypass line

75

Return-bypass line

77

valve assembly

79

pump

81

overflow

83

temperature sensor

85

electrical energy

100

contraption

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]
• - DE 102007042836 [0002]

Cited non-patent literature

• - "Perspectives of Mobile SCR Technology" by Dr. Eberhard Jacob, 15th Aachen Colloquium Automotive and Engine Technology, available at: 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 (9)

Contraption ( 1 ) for the exhaust aftertreatment of an exhaust gas stream ( 7 ) of an internal combustion engine ( 11 ) of a motor vehicle ( 3 ) by means of an ammonia-releasing liquid, with a storage container ( 35 ) for storing the liquid, wherein a tempering device ( 47 ) is provided for controlling the temperature of the liquid, characterized in that the temperature control device ( 47 ) a heater ( 49 ) of the internal combustion engine ( 11 ) assigned. Apparatus according to claim 1, characterized in that the temperature control device ( 47 ) for cooling the liquid an air conditioning circuit ( 51 ) of the motor vehicle ( 3 ) assigned. Device according to one of the preceding claims, characterized in that the temperature control device ( 47 ) by means of a valve arrangement ( 77 ) the heater ( 49 ) is assigned or assigned. Device according to the preceding claim, characterized in that the heater ( 49 ) by means of the valve arrangement ( 77 ) of the temperature control device ( 47 ) and / or the internal combustion engine ( 11 ) can be decoupled. Device according to one of the preceding claims, characterized in that the temperature control device ( 47 ) a second heat exchanger ( 53 ) of the air conditioning circuit ( 51 ) assigned. Device according to the preceding claim, characterized in that the second heat exchanger ( 53 ) between an evaporator ( 63 ) and a compressor ( 57 ) of the air conditioning circuit ( 51 ) is switched. Device according to one of the preceding claims, characterized in that tempering device ( 47 ) an electrically operable heater ( 41 ) for heating the storage container ( 35 ) having. Device according to one of the preceding claims, characterized by a temperature control device ( 47 ) acting central control unit ( 45 ) for controlling and / or regulating a temperature of the in the reservoir ( 35 ) stored liquid. Motor vehicle ( 3 ) with a device ( 1 ) for the exhaust aftertreatment of an exhaust gas stream ( 7 ) of an internal combustion engine ( 11 ) of the motor vehicle ( 3 ) according to any one of the preceding claims.