DE102014226749A1 - Method and apparatus for testing a heating system in an SCR exhaust aftertreatment system - Google Patents

Abstract

A method and apparatus for testing a temperature sensor and an electric heater in an exhaust aftertreatment system of an internal combustion engine is proposed, wherein the exhaust aftertreatment system includes at least one reduction catalyst, a reductant reservoir for storing liquid reductant, a fill level sensor for determining the amount of reductant in the reductant reservoir, a reductant pump for conveying the reducing agent and a metering device for introducing the reducing agent into an exhaust pipe of the internal combustion engine. The temperature sensor and the electric heater are arranged inside the reducing agent reservoir. In an operating state of the internal combustion engine, in which frozen reducing agent is present in the reducing agent reservoir due to the prevailing temperatures, the heating device is switched on and checks whether the signal of the temperature sensor (T_RED) rises from a starting temperature (T_RED_ST) at the switch-on time (t0) of the heating device and during the heating process when reaching the freezing point (T_RED_G) of the reducing agent, the temperature (T_RED) of the reducing agent for a predetermined period of time (t2-t1) remains constant. The temperature sensor and the heating device are recognized as error-free if the temperature (T_RED) remains constant during the predetermined period of time (t2-t1) and then rises within a predetermined period of time (t3-t0) up to a predetermined desired value (T_RED_SOLL).

Description

The invention relates to a method and a device for checking a heating system in an SCR exhaust aftertreatment system of an internal combustion engine.

To reduce pollutants, in particular for the reduction of nitrogen oxides, various methods have been established in which reducing fluids (gases or liquids) are introduced into the exhaust system of an internal combustion engine.

For the reduction of nitrogen oxides, especially the SCR technology (selective catalytic reduction) has proven to be reduced in the oxygen-rich exhaust gas nitrogen oxides (NO _x ) using ammonia or a corresponding convertible to ammonia precursor selectively to nitrogen and water. Preference is given here to aqueous urea solutions. The urea solution is hydrolyzed by means of hydrolysis catalysts or directly on the SCR catalyst to ammonia and carbon dioxide. For this purpose, the urea solution is carried in one or more tanks and fed with a conveyor to a metering system, which introduces the urea solution before the hydrolysis or the SCR catalyst in the exhaust gas stream.

An aqueous urea solution having a urea content of 31.8-33.2 percent by weight, which is marketed under the trademark "AdBlue", has proven particularly suitable as a reducing agent. As with other reductant solutions, this urea solution also has the problem that it has a relatively low freezing point (-11.5 ° C) and frozen reductant can no longer be promoted to the catalyst. This has a failure of the exhaust aftertreatment system in particular in winter, which can lead to an inadmissibly high emissions of harmful exhaust gas components. In addition, the volume of the aqueous urea solution increases by about 10% during freezing. This can cause damage to the individual components of the SCR exhaust aftertreatment system.

For the uptake and proper operation of such an exhaust aftertreatment system, it is therefore necessary to equip in particular the tank with heating systems, which melt the frozen liquid in the tank and convert it into a liquid, that is flowable state of aggregation.

Systems are known from the prior art, to coat the liquid tanks in motor vehicles with heating foils or heating mats to thaw the liquid frozen in the tank. However, arranged outside of the tank wall heating foils or heating mats have only poor efficiencies, because a large part of the heat generated is not passed to the melting of the frozen liquid in the tank, but is discharged as power loss in the tank environment. Therefore, either an increase in the heating temperature and / or the on-time of the heating is required to heat the tank or at least the part of the tank from which the reducing agent is taken, so that the reducing agent is thawed and / or thawed sufficiently quickly and thus remains in a flowable state of aggregation ( EP 1 767 417 A1 . DE 10 2007 005 004 A1 ).

Moreover, it is known from the prior art, in addition to the tank, also to heat at least part of the reducing agent lines, the reducing agent pump, the reducing agent filter and / or the reducing agent injector ( DE 10 2008 061 471 A1 . WO 2006/90182 A1 . EP 2 133 527 A1 ).

In order to re-thaw frozen reducing agent or to delay or prevent freezing of the reducing agent, the heating of said components of the SCR exhaust aftertreatment system is usually only switched on when a temperature sensor installed in this system reaches a temperature value near or below the freezing point of the Indicating reducing agent. By means of the temperature sensor thus the need and the duration of the heating process are determined.

A delayed release of the injection of the reducing agent due to a false signal of the temperature sensor or too slow heating due to a too low heat output of the heater have a direct influence on the emission behavior of the internal combustion engine. Therefore, diagnostic routines must be provided for both the temperature sensor and the heater.

So far, the temperature sensor has been checked for implausible values, ie, too low or too high temperature values or physically impossible temperature values. Alternatively or additionally, a plausibility check can take place with the values of other temperature sensors, for example the values of a coolant temperature or the values of an ambient temperature sensor. With the first method, only values outside the permissible temperature range can be detected as faulty. In the second method also large deviations must be tolerated because due to the low temperature dynamics in the SCR exhaust aftertreatment system in the error-free State large differences to the values of the comparison, other temperature sensors are possible.

In particular, if the reducing agent tank is protected by means of thermal insulation in order to keep the heat loss low, this means that the temperature fluctuations are relatively low and very sluggish. This makes it difficult to diagnose the temperature sensor, since the signal change is very low. In particular, a so-called "hanging temperature sensor" can only be determined with difficulty. In this context, a "hanging temperature sensor" is understood to be a temperature sensor whose signal (measured value) does not change or changes only very slightly over a relatively long period of time or shows only slight dynamics with regard to its output measured value.

The object of the invention is therefore to provide a simple and improved method and an apparatus for diagnosing a temperature sensor arranged in the reducing agent reservoir and a heating device of an SCR exhaust aftertreatment system of an internal combustion engine present in the reducing agent reservoir.

This object is solved by the subject matters of the independent claims. Preferred developments are specified in the dependent claims.

The invention is characterized by a method and an apparatus for checking a temperature sensor and an electric heater in an exhaust aftertreatment system of an internal combustion engine, wherein the exhaust aftertreatment system at least one reduction catalyst, a reducing agent reservoir for storing liquid reducing agent, a level sensor for determining the amount of reducing agent in the reducing agent tank, a reducing agent pump for conveying the reducing agent and a metering device for introducing the reducing agent into an exhaust pipe of the internal combustion engine. The temperature sensor and the electric heater are arranged inside the reducing agent reservoir. In an operating state of the internal combustion engine in which frozen reducing agent is present in the reducing agent reservoir due to the prevailing temperatures, the heating device is switched on and checks whether the signal of the temperature sensor rises from a starting temperature at the time of switching on the heater and during the heating process when reaching the freezing point of the reducing agent Temperature of the reducing agent remains constant for a predetermined period of time. The temperature sensor and the heating device are recognized as error-free if the temperature remains constant during the predetermined period of time and then rises within a predetermined period of time up to a predetermined desired value.

The invention is based on the finding that in the transition from a solid state of matter, i. Frozen reducing agent to the liquid state of the state of fusion heat is necessary, so that in the region of the freezing point of the reducing agent despite continuous heating of the reducing agent, a section of constant temperature of the reducing agent, also referred to as plateau sets. This property is exploited in the method and the device according to the invention in order to check on the functioning thereof a temperature sensor installed in the reducing agent tank and the heating means for the reducing agent arranged in the reducing agent tank.

By evaluating the characteristic expression of the temperature signal in the region of the freezing point thus errors of the temperature sensor and the heater can be detected from each other in a simple manner.

With the method and the device according to the invention can be detected on a too low heat output of the heater or incorrect information about the amount of reducing agent in the reducing agent reservoir, when the time during which the signal of the temperature sensor in the freezing point of the reducing agent to a constant Value remains longer than the predetermined period of time.

This predetermined period of time can be easily determined from the amount of reducing agent in the reducing agent reservoir and the nominal heating power of the heater. For this purpose, the signal of an already existing level sensor is used in or on the reducing agent reservoir, while the nominal heating power of the heater is predetermined and thus known.

Advantageously, the predetermined period is stored in a map of a data memory of the exhaust aftertreatment system controlling and regulating dosing control device.

If the exhaust aftertreatment system has a return line for the reducing agent to the reducing agent reservoir, with the aid of the reducing agent pump with the dosing device kept closed, a circulation of the Reducing agent can be achieved, which allows a good mixing of the medium and thus leads to a significant expression of the plateau.

Further advantageous embodiments of the method and the device will become apparent in connection with the description of a preferred embodiment.

The invention will be explained in more detail with reference to the drawing. Show it:

1 a block diagram of an internal combustion engine with associated SCR exhaust aftertreatment system, in which the diagnostic method according to the invention is used, and

2 a diagram with different temperature curves to illustrate the diagnostic procedure.

In 1 is very simplified in the form of a block diagram shown an at least temporarily operated with excess air internal combustion engine with an associated exhaust aftertreatment system. Only those parts are shown, which are necessary for the understanding of the invention. In particular, has been dispensed with the representation of the fuel circuit. In this embodiment, as a combustion engine, a diesel internal combustion engine is shown, and as a reducing agent for after-treatment of the exhaust gas, aqueous urea solution is used. The inventive method is also applicable to other types of internal combustion engines, which are at least partially operated with excess air and use as a reducing agent liquids that tend to freeze at low ambient temperatures.

The internal combustion engine 1 is via a suction line 2 supplied to the necessary air for combustion. An injection system, which can be designed, for example, as a high-pressure accumulator injection system (common rail) with injection valves, the fuel KST directly into the cylinders of the internal combustion engine 1 inject is with the reference numeral 3 designated. The exhaust gas of the internal combustion engine 1 flows over an exhaust pipe 4 to an exhaust aftertreatment system 5 and from this via a silencer, not shown, into the open.

For controlling and regulating the internal combustion engine 1 is a known electronic control device 6 , also referred to as engine control or electronic control unit, ECU, via a bus system shown here only schematically 7 , which includes data and control lines, with the internal combustion engine 1 connected. About this bus system 7 Among other things, signals from sensors such as load sensor, speed sensor and temperature sensors for intake air, charge air and coolant, as well as signals for actuators (eg injectors, actuators) between the internal combustion engine 1 and the controller 6 transfer.

The exhaust aftertreatment system 5 has a reduction catalyst (SCR catalyst) 8th on, which includes a plurality of series-connected, unspecified catalyst units. Downstream and / or upstream of the reduction catalyst 8th may additionally be arranged in each case an oxidation catalyst (not shown).

Furthermore, a dosing control unit 9 (DCU, dosing control unit), a reducing agent reservoir 11 , a dosing unit to be described later 10 and a metering device 15 in the form of an injector, for introducing reducing agent 19 upstream of the reduction catalyst 8th in the exhaust pipe 4 intended.

The reducing agent 19 , preferably aqueous urea solution, is in the reductant reservoir 11 stored and, if necessary, the metering device 15 fed. For this purpose, the metering unit 10 an electrically controllable reducing agent pump 101 on the suction side via a reducing agent filter 102 with a sampling line 25 which is in the reducing agent reservoir 11 protrudes and the pressure side with a supply line 16 with the dosing device 15 connected is.

On or in the reducing agent reservoir 11 is a sensor 14 for detecting the level of the reducing agent 19 in the reducing agent reservoir 11 intended. The signal of this sensor 14 is the dosing control unit 9 fed.

The reducing agent reservoir 11 has an electric heater 12 on. This heater 12 For example, it can be in the form of a heating mat, heating foil, heating plate, heating element, heating coil or heating coil and serves for melting frozen reducing agent 19 within the reductant reservoir 11 , At the heater 12 or at least in the immediate vicinity of the heater 12 and in the flow direction of the reducing agent 19 seen before the sampling line 25 is a temperature sensor 13 provided, the signal also the dosing control unit 9 is supplied. Inside the housing of the dosing unit 10 branches at the pressure-side connection of the reducing agent pump 101 from the supply line 16 a return line 104 which back into the reductant reservoir 11 leads. With the help of one, also within the case of the dosing 10 arranged, electrical shut-off valve 105 can the return line 104 be shut off or released.

The reducing agent filter 102 , as well as at least parts of the sampling line 25 , the feed line 16 and the return line 104 have electric heaters 106 . 26 . 24 . 27 on. These may include, for example, a heating coil or a heated line or hose section. This can ensure that reducing agent 19 , which turns off after stopping the internal combustion engine 1 and deactivated reducing agent pump 11 still in the components, not freeze or can be thawed quickly after the restart. This is especially important for systems in which when stopping the internal combustion engine 1 no empty suction of the line branches takes place because, for example, a reducing agent pump 101 is used, which does not allow reverse rotation.

With the help of the return line 104 and open recirculation valve 105 is when the reducing agent pump is switched on 101 and closed metering device 15 a recirculation flow of reducing agent 19 achieved, whereby a good mixing takes place and temperature differences within the reducing agent reservoir 11 be avoided.

Furthermore, within the housing of the dosing unit 10 at the pressure-side connection of the reducing agent pump 101 a sensor device 103 provided, which information about the pressure and the temperature of the reducing agent 19 to the dosing control unit 9 supplies.

The dosing control unit 9 preferably comprises a computing unit (processor) 28 that with a program memory 29 and a value memory (data memory) 30 is coupled. In the program memory 29 and the value memory 30 are stored programs or values necessary for the operation of the SCR exhaust aftertreatment system 5 are necessary.

The dosing control unit 9 is for mutual data transfer via an electric bus system 17 with the control device 6 connected. About the bus system 17 are the for calculating the amount of reducing agent to be dosed 19 relevant operating parameters of the internal combustion engine 1 , such as speed, intake air mass, injected fuel mass, exhaust gas mass flow, operating temperature, charge air temperature, start of injection, etc. the dosing control unit 9 to hand over.

Based on these parameters, the pressure in the supply line 16 and measured values for the exhaust gas temperature and the NO _x content are calculated by the dosing control unit 9 in a known manner, the amount of reducing agent to be injected 19 and outputs a corresponding electrical signal to the metering device 15 from. Through the injection into the exhaust pipe 4 The aqueous urea solution is hydrolyzed and mixed. In the catalyst units of the reduction catalyst 8th the catalytic reduction of the NO _x in the exhaust gas to N ₂ and H ₂ O.

The dosing control unit 9 controls and / or regulates the electric heater 12 in the reducing agent reservoir 10 and the electric heaters 24 . 26 . 27 in or on the lines 16 . 25 . 104 , Furthermore, in the program memory 29 of the dosing control unit 9 by software a function to check the temperature sensor 13 in the reducing agent reservoir 11 and the heater disposed therein 12 implemented as they are based on 2 will be explained in more detail.

The dosing device 15 for introducing the reducing agent 19 in the exhaust pipe 4 can be realized in an advantageous manner as a conventional, with respect to the choice of materials slightly modified, driven by a solenoid low-pressure gasoline injection valve, for example, in one with a wall of the exhaust pipe 4 firmly connected valve receiving device is releasably attached.

In a simpler embodiment of the metering device 15 this may be provided in the form of a nozzle and the metering of the reducing agent 19 takes place solely by driving the reducing agent pump 11 by appropriate signals of Dosiersteuergerätes 9 ,

In this embodiment, the control device 6 and the dosing control unit 9 shown and described as separate components. This has the advantage that the SCR exhaust aftertreatment system 5 can also be retrofitted into existing vehicle concepts. But it is also possible, the functionality of the Dosiersteuergeräts 9 in the control device 6 the internal combustion engine 1 to integrate, resulting in a compact and cost-effective solution for the exhaust aftertreatment system 5 results.

Based on the diagrams in 2 becomes the method of checking the temperature sensor 13 and the heater 12 explained in more detail.

The diagnostic procedure is only performed when in the reductant reservoir 11 frozen reducing agent 19 is present.

In the upper part of the 2 is the electrical drive signal for within the reducing agent reservoir 11 arranged heating device 12 shown. The high level 1 is representative of an activated heating device 12 and the low level 0 is representative of an off heater 12 ,

In the lower part of the 2 different signal curves are shown, wherein on the abscissa the time t and on the ordinate the temperature T_RED of the reducing agent 19 is applied. In addition, selected temperature values are entered on the ordinate. The reference character T_RED_ST is the temperature of the reducing agent 19 at the start of the diagnosis, with T_RED_G the freezing temperature of the reducing agent 19 and with T_RED_SOLL a setpoint for the temperature of the reducing agent 19 characterized. In the case of a commercially available aqueous urea solution (eutectic 32.5% solution), which is sold under the brand name "Adblue", the freezing temperature T_RED_G is -11.5 ° C. In addition, on the right side of the diagram, an area for one due to the heating effect of the heater 13 minimally expected temperature increase ΔT_RED_MIN drawn.

The value for the minimum expected temperature increase ΔT_RED_MIN depends on the starting temperature T_RED_ST, the level of the reducing agent 19 in the reducing agent reservoir 11 and the heating power of the heater 13 in the data store 30 of the dosing control unit 9 stored.

Checking the temperature sensor 13 and the heater 12 begins at a time t0 at which the heater 12 is turned on. The temperature T_RED of the reducing agent 19 is at this time t0 well below its freezing point T_RED G and is designated T_RED_ST. For a faultless temperature sensor 13 and faultless heater 12 results in a time course of the reducing agent temperature T_RED during the heating, as indicated by a characteristic KL1 in the 2 is drawn.

With constant supply of heat, the reducing agent heats up 19 continuously and the temperature T_RED initially increases relatively strongly until a time t1 and then remains constant when the freezing temperature T_RED_G is reached for a time t2-t1, ie despite the continued activation of the heating device 12 If the temperature T_RED does not continue to increase, it remains at this temperature due to the necessary heat of fusion in the region of the freezing point T_RED_G, so that a plateau occurs. The of the heater 12 supplied energy is needed to the reducing agent 19 from the solid to the liquid state. In the process, binding forces between molecules or atoms are overcome without increasing their kinetic energy and thus their temperature. The heat of fusion for as a reducing agent 19 Preferably used, aqueous urea solution having a urea content of 31.8-33.2 weight percent is 270J / g.

Depending on the installation position of the temperature sensor 13 in relation to the heater 12 and depending on the length of the heating path between the reducing agent reservoir 11 and temperature sensor 13 For example, the position of the plateau may be slightly offset from the freezing point T_RED_G.

From the time t2 is liquid reducing agent 19 before and the temperature T_RED rises due to the heat input again until it reaches a predetermined setpoint T_RED_SOLL at a time t3.

A good mixing of the reducing agent 19 is necessary to obtain a clear expression of this plateau. To ensure this is done with the return valve open 105 , switched-on reducing agent pump 101 and closed metering device 15 the reducing agent 19 via the return line 104 again the reducing agent reservoir 11 fed. This can temperature differences within the reducing agent reservoir 11 be avoided.

The temporal length of the plateau is dependent on the amount of heat supplied, which by the output heating power of the heater 12 is determined and of the in the reducing agent tank 11 existing amount of reducing agent 19 , The heating power for a properly functioning heater 12 is known (nominal heating power), the amount of in the reducing agent reservoir 11 existing reducing agent 19 is from the signal of the level sensor 14 derived. From these two sizes, the length of the plateau can be calculated.

Increases when thawing the reducing agent 19 the temperature T_RED of the reducing agent 19 Although on, but there is no formation of a plateau, or is the plateau not in the range of the freezing point T_RED_G, so is a defective temperature sensor 13 closed. Such a temperature profile is in the lower half of 2 marked with a characteristic KL2.

Increases when thawing the reducing agent 19 the temperature T_RED of the reducing agent 19 A plateau also occurs in the region of the freezing point T_RED_G, but the plateau length gives way From the calculated length, the heating power is not sufficient and it is due to a too weak heater or an incorrect signal of the level sensor 14 closed. As from the characteristic KL3 in 2 As can be seen, the plateau is significantly longer than in a faultless system (characteristic KL1).

Shows the signal of the temperature sensor 13 after switching on the heater 12 At time t3 no change whatsoever, ie the temperature T_RED persists even after expiration of the period of time t3-t0 at the starting temperature T_RED_ST, then a hanging temperature sensor or a total failure of the heating device is activated 12 recognized. Such a case is in the 2 marked with the characteristic KL4.

For detected errors of the temperature sensor 13 or the heater 12 An entry is made in a fault memory within the dosing control unit 9 or within the controller 6 the internal combustion engine 1 , In addition, when an error occurs, a corresponding signaling by means of an error display device to the driver of the internal combustion engine 1 driven vehicle done.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

2

suction

3

injection

4

exhaust pipe

5

aftertreatment system

6

Control device, engine control unit, (ECU, electronic control unit)

7

bus system

8th

Reduction catalyst, SCR catalyst

9

Dosing control unit, (DCU, dosing control unit)

10

dosing

101

electric reducing agent pump

102

Reductant filter

103

sensor device

104

Return line

105

Recirculation valve

106

Heating device of the reducing agent filter

11

Reducing agent reservoir

12

Heating device of the reducing agent reservoir

13

Temperature sensor in the reducing agent reservoir

14

level sensor

15

Dosing device, injector

16

feed

17

bus system

19

reducing agent

24

Heating device of the supply line

25

withdrawal line

26

Heating device of the sampling line

27

Heating device of the return line

28

Arithmetic unit, processor

29

program memory

30

Data memory, value memory

KST

fuel

F_KEY

 Function for the diagnosis of the temperature sensor and the heater in the reducing agent reservoir

KL1-KL4

curve

t

Time

t0-t3

timings

T_RED

 Temperature of the reducing agent

T_RED_ST

 Temperature of the reducing agent at the start of the diagnosis

T_RED_G

 Freezing point of the reducing agent

ΔT_RED_MIN

minimally expected increase in the temperature of the reducing agent

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• EP 1767417 A1 [0006]
• DE 102007005004 A1 [0006]
• DE 102008061471 A1 [0007]
• WO 2006/90182 A1 [0007]
• EP 2133527 A1 [0007]

Claims (6)

Method for checking a temperature sensor ( 13 ) and an electric heater ( 12 ) in an exhaust aftertreatment system ( 5 ) an internal combustion engine ( 1 ), wherein - the exhaust aftertreatment system ( 5 ) at least one reduction catalyst ( 8th ), a reducing agent reservoir ( 11 ) for storing liquid reducing agent ( 19 ), a level sensor ( 14 ) for determining the amount of reducing agent ( 19 ) in the reducing agent tank ( 11 ), a reducing agent pump ( 101 ) for conveying the reducing agent ( 19 ) and a metering device ( 15 ) for introducing the reducing agent ( 19 ) in an exhaust pipe ( 4 ) of the internal combustion engine ( 1 ), - the temperature sensor ( 13 ) and the electric heater ( 12 ) within the reducing agent storage tank ( 11 ) are arranged, characterized by the following steps: a) in an operating state of the internal combustion engine ( 1 ), in which, due to the prevailing temperatures, frozen reducing agent ( 19 ) in the reducing agent reservoir ( 11 ), the heating device ( 12 ) is switched on, b) it is checked whether the signal of the temperature sensor ( 13 ) starting from a starting temperature (T_RED_ST) at the switch-on time (t0) of the heating device ( 12 ) and during the heating process when the freezing point (T_RED_G) of the reducing agent ( 19 ) the temperature (T_RED) of the reducing agent ( 19 ) remains constant for a predetermined period of time (t2-t1), c) the temperature sensor ( 13 ) and the heater ( 12 ) are recognized as being error-free if the temperature (T_RED) remains constant during the predetermined period of time (t2-t1) and then rises within a predetermined period of time (t3-t0) up to a predetermined desired value (T_RED_SOLL). A method according to claim 1, characterized in that on too low heating power of the heater ( 12 ) or incorrect information about the amount of reducing agent ( 19 ) in the reducing agent reservoir ( 11 ) is detected when the period of time during which the signal of the temperature sensor ( 13 ) in the region of the freezing point (T_RED_G) of the reducing agent 819) remains at a constant value, is longer than the predetermined period of time (t2-t1). Method according to claim 1 or 2, characterized in that the period of time (t2-t1) is determined from the amount of reducing agent ( 19 ) in the reducing agent reservoir ( 11 ) and the nominal heating power of the heater ( 12 ). Method according to Claim 3, characterized in that the predetermined time period (t2-t1) in a characteristic field of a data memory ( 30 ) of the exhaust aftertreatment system ( 5 ) controlling and regulating dosing control device ( 9 ) is stored. Method according to one of the preceding claims, characterized in that during the heating of the reducing agent ( 19 ) with the reducing agent pump switched on ( 101 ) and closed metering device ( 15 ) a circulation of the reducing agent ( 19 ) via a return line ( 104 ) into the reducing agent reservoir ( 11 ) is carried out. Device for checking a temperature sensor ( 13 ) and an electric heater ( 12 ) in an exhaust aftertreatment system ( 5 ) of an internal combustion engine, characterized in that the device is designed and arranged such that the method according to any one of claims 1-5 executable.

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