DE102016115322A1 - Apparatus and method for regeneration of a particulate filter - Google Patents

Abstract

The invention relates to a device for regenerating a particulate filter in the exhaust passage of a turbocharged internal combustion engine, wherein a turbine of the turbocharger is arranged in an exhaust passage of the internal combustion engine and drives a compressor for supplying fresh air to the internal combustion engine, wherein an additional electric compressor is provided, which in addition to the compressor of Turbocharger compresses the fresh air of the internal combustion engine.

Description

The invention relates to a device and a method for the regeneration of a particulate filter in the exhaust passage of an internal combustion engine according to the preamble of the independent claims.

The current and increasingly stringent future exhaust gas legislation places high demands on engine raw emissions and the exhaust aftertreatment of internal combustion engines. Furthermore, the vehicle and engine manufacturers are required to reduce the consumption of internal combustion engines and the associated CO2 emissions. With the introduction of the next EU6 emissions legislation, a particle limit for gasoline engines has been laid down for the first time. This may mean that the use of a particulate filter is also necessary in motor vehicles with a gasoline engine. Over the life of the internal combustion engine, this particulate filter is loaded with ash and soot particles. Ash particles represent an inorganic and non-regenerable loading of the soot particle filter. The particulates stored in the particulate filter, which arise during operation of the gasoline engine can be oxidized at correspondingly high temperatures and excess oxygen in the exhaust channel and the particulate filter thus regenerated.

Methods for the regeneration of a particulate filter in the exhaust passage of a gasoline engine are known from the prior art, in which the gasoline engine is operated in a lean operation and thus there is an excess of oxygen in the exhaust gas passage. Furthermore, regeneration methods of the particulate filter are known in which secondary air is introduced by means of a secondary air pump in the exhaust passage of the internal combustion engine to provide a sufficient amount of oxygen for the regeneration of the particulate filter.

A disadvantage of the known solutions, however, is that they are associated with a high control engineering effort to simultaneously achieve the necessary for the regeneration temperature and an excess of oxygen in the exhaust duct. In addition, an additional secondary air pump increases the cost of the exhaust aftertreatment device.

The performance requirements of modern gasoline engines in terms of performance are steadily rising. In order to provide a high torque even at low speeds and low exhaust gas volumes of the internal combustion engine, the use of an electrically driven compressor (eBooster) offers. This electrically driven compressor supports the turbocharger during boost pressure build-up. Due to the fact that the eBooster does not have an additional exhaust gas turbine, the eBooster does not cause any additional exhaust backpressure.

From the DE 100 23 022 A1 an internal combustion engine with an exhaust gas turbocharger is known, wherein an additional compressor is connected in parallel or in series with the exhaust gas turbocharger, wherein the auxiliary compressor from the drive circuit of the engine can be driven independently, wherein the auxiliary compressor in addition to the exhaust gas turbocharger compressed air to overcome a so-called turbo lag. In addition, a secondary air line is provided, by means of the additional compressor air can be conveyed into the exhaust passage of the internal combustion engine to bring a catalyst in the exhaust duct to operating temperature faster in a cold start phase of the engine.

From the DE 102 31 107 A1 an internal combustion engine with an exhaust gas turbocharger is known, wherein the compressor of the exhaust gas turbocharger is driven by an electric motor except by the exhaust gas turbine. In this case, the speed of the compressor can be adjusted independently of the speed or power of the internal combustion engine and independently of the exhaust gas flow by the electric motor. The compressor is connected via a secondary air line to the exhaust passage of the internal combustion engine in order to support the heating of a catalyst can.

Moreover, from the DE 198 40 629 A1 an internal combustion engine for a motor vehicle with an exhaust gas turbocharger and a secondary air blower known. In this case, the secondary air pump is provided to inject fresh air upstream of a catalyst in the exhaust passage of the internal combustion engine and thus to support a heating of the catalyst. In addition, the secondary air pump can be used to assist the compressor of the turbocharger and to supply the internal combustion engine with compressed air.

The invention is based on the object to provide an apparatus and a method with which a simple and reliable regeneration of the particulate filter is possible in most operating conditions of an internal combustion engine with turbocharging.

The object is achieved by a device for exhaust aftertreatment of an internal combustion engine with an exhaust gas turbocharger having a arranged in an exhaust passage of the internal combustion engine, which in turn drives a arranged in a fresh air line of the engine compressor, and with an electrically driven auxiliary compressor, which is substantially independent of the load and the speed the internal combustion engine compressed fresh air in the fresh air line to the engine, and with a secondary air line which connects the auxiliary compressor with the exhaust passage of the internal combustion engine, wherein the secondary air line opens upstream of a particulate filter in the exhaust passage of the internal combustion engine. As a result, regeneration of the particle filter, that is to say oxidation of the soot particles retained in the particle filter, can take place without leaving stoichiometric operation of the internal combustion engine. In addition, an amount of oxygen necessary for the regeneration of the particulate filter can thus be introduced into the exhaust gas duct substantially independently of the rotational speed and the load of the internal combustion engine.

The features specified in the dependent claims advantageous developments and improvements of the independent claim specified device for exhaust aftertreatment of the internal combustion engine are possible.

In a preferred embodiment of the invention it is provided that in the exhaust passage in the flow direction of the exhaust gas of the internal combustion engine through the exhaust passage upstream of the particulate filter, a catalyst is arranged, wherein the secondary air line downstream of the catalyst and upstream of the particulate filter opens into the exhaust passage. As a result, the oxygen supplied to the exhaust duct via the secondary air duct can be used directly for the regeneration of the particulate filter and it eliminates a dead time in which otherwise the oxygen storage capacity of the catalyst is first exhausted when introducing the oxygen upstream of the catalyst.

In a further preferred embodiment of the invention, it is provided that in the secondary air line downstream of the auxiliary compressor and upstream of a junction of the secondary air line in the exhaust passage a shut-off for closing the secondary air line or for throttling a flow through the secondary air line is arranged. As a result, an undesired backflow of exhaust gas against the flow direction provided for the secondary air, in particular when the auxiliary compressor is switched off, can be avoided.

It is particularly preferred if the shut-off is designed as a throttle. A throttle is a simple and inexpensive component to control the flow of air from the booster compressor to the exhaust duct through the secondary air duct.

In a preferred embodiment of the invention, the fresh air line downstream of the compressor into a first channel and a second channel, wherein in the first channel, a throttle valve for controlling the air supply of the internal combustion engine and in the second channel of the additional compressor is arranged. A parallel guidance of the fresh air through a first and a second channel in the region of the additional compressor makes it possible for the fresh air to flow past the auxiliary compressor into the combustion chambers of the internal combustion engine and thus no additional flow resistance in the fresh air duct is created by the auxiliary compressor.

According to a preferred development of the invention, it is provided that the first channel and the second channel are connected downstream of the throttle valve and downstream of the auxiliary compressor by a third channel, wherein in the third channel another shut-off element, in particular a further throttle valve, for closing the third channel or for throttling a flow through the third channel is arranged. Through the third channel, a simple connection of the compressed by the additional compressor fresh air to the fresh air line is possible. Thus, compressed fresh air can be conveyed in parallel through the compressor and the additional compressor in the direction of the inlet of the internal combustion engine.

According to the invention, a method for the regeneration of a particulate filter in the exhaust duct of an internal combustion engine is proposed, wherein the fresh air is supplied to the air supply of the internal combustion engine by a compressor which is driven by a turbine of an exhaust gas turbocharger of the internal combustion engine, wherein an additional compressor is provided, which is electrically driven and in Essentially, regardless of a speed or load of the internal combustion engine, a compression of the fresh air allows, and wherein the fresh air compressed by the auxiliary compressor via a secondary air line connecting the additional compressor with the exhaust duct, is injected upstream of the particulate filter in the exhaust duct. The inventive method regeneration of the particulate filter is possible, in which the internal combustion engine is operated continuously with a stoichiometric combustion air ratio. Thus, there is also no increase in HC, CO and NOx emissions during regeneration since they are converted by the catalyst.

In a further improvement of the method, it is provided that a shut-off device in the secondary air line is only opened when a sufficient temperature in the exhaust gas channel is achieved for the regeneration of the particle filter. This avoids that the additional compressor secondary air in operating conditions in the Flue gas channel blown in, where this is not necessary or even harmful.

According to an advantageous further development of the method, provision is made for the amount of air in the regeneration of the particulate filter to be adjusted by the additional compressor or the shut-off valve in the secondary air line such that an exhaust gas air ratio λ _A of 1.05 to 1.3 is established in the exhaust gas channel upstream of the particulate filter , By means of a superstoichiometric exhaust gas, sufficient oxygen is available to oxidize the soot particles retained in the particle filter. In this case, an exhaust gas air ratio λ _A in a range of 1.05-1.3 is particularly favorable, since the risk that there will be an uncontrolled Rußabbrand on the particulate filter and an associated thermal damage to the particulate filter is low.

According to a further, advantageous improvement of the method, it is provided that with a simultaneous request of fresh air compressed by the additional compressor for an additional fresh air supply of the internal combustion engine and of secondary air for the regeneration of the particulate filter, the fresh air supply for the internal combustion engine takes precedence over the provision of secondary air for the regeneration of the particulate filter has. By prioritizing the fresh air supply of the internal combustion engine before the secondary air supply, a higher torque and, associated therewith, an improved response and / or greater power of the internal combustion engine can be achieved. Since such an operating state, in particular a maximum acceleration, but only briefly stops, the regeneration of the particulate filter can be continued afterwards. In addition, such operation of the internal combustion engine increases the exhaust gas temperature, so that a sufficient exhaust gas temperature for the regeneration of the particulate filter is maintained.

Further preferred embodiments of the invention will become apparent from the remaining, mentioned in the dependent claims characteristics.

The various embodiments of the invention mentioned in this application are, unless otherwise stated in the individual case, advantageously combinable with each other.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

1 An embodiment of an inventive device for the regeneration of a particulate filter in the exhaust passage of an internal combustion engine; and

2 a flowchart for performing a method according to the invention for the regeneration of a particulate filter in the exhaust passage of an internal combustion engine.

1 shows an internal combustion engine 10 , the inlet side with a fresh air line 22 and exhaust side with an exhaust duct 12 connected is. In the exhaust duct 12 is in the flow direction of an exhaust gas of the internal combustion engine 10 downstream of an outlet 56 of the internal combustion engine 10 a turbine 14 an exhaust gas turbocharger 20 arranged. At the turbine 14 is a bypass with a waste gate 46 provided in a known manner a pressure reduction in the exhaust duct 12 to enable. In the flow direction further downstream in the exhaust duct 12 is a catalyst 16 , preferably a three-way catalyst. Further downstream is in the exhaust duct 12 a particle filter 18 arranged, which soot particles from the exhaust gas of the internal combustion engine 12 filter out and attach to its surface. In the exhaust duct 12 is downstream of the turbine 14 and upstream of the catalyst 16 a first lambda probe 48 provided to the internal combustion engine 10 to adjust to a stoichiometric combustion air ratio λ _E = 1 and an effective and efficient exhaust aftertreatment by the catalyst 16 to enable.

In the fresh air line 22 is a compressor 24 arranged, which through the turbine 14 the exhaust gas turbocharger 20 is driven and the internal combustion engine 10 thus supplied with pre-compressed air. In the flow direction of the fresh air downstream of the compressor 24 shares the fresh air pipe 22 in a first channel 40 and a second channel 42 , where in the first channel 40 a first throttle 38 for controlling the internal combustion engine 10 supplied fresh air is arranged. In the second channel 42 is an additional compressor 26 arranged, which is electrically driven and thus substantially independent of the speed and the load of the internal combustion engine 10 allows a compression of fresh air. The additional compressor 26 is via a secondary air line 28 with the exhaust duct 12 connected, wherein the secondary air line 28 at a junction 30 downstream of the catalyst 16 and upstream of the particulate filter 18 in the exhaust duct 12 empties. In the secondary air line 22 is a shut-off element 32 , preferably a throttle valve 34 , arranged, with the an air supply to the exhaust duct 12 can be opened or closed. The first channel 40 and the second channel 42 are downstream of the first throttle 38 and downstream of the auxiliary compressor 26 over a third channel 44 interconnected, wherein in the third channel 44 another shut-off element 36 , In particular, a further throttle valve, is provided.

In the exhaust duct 12 is downstream of the confluence 30 and upstream of the particulate filter 18 another oxygen sensor, in particular a further lambda probe 50 arranged to exhaust air ratio λ _A before entering the particulate filter 18 to investigate. The lambda probes 48 . 50 and the auxiliary compressor 26 are via signal lines 54 with a control unit 52 of the internal combustion engine 10 connected and can be electrically controlled via this.

In a normal operation < 100 > the internal combustion engine sucks 10 Fresh air through the fresh air line 22 which, through the compressor 22 the exhaust gas turbocharger 20 is compressed and the internal combustion engine 10 is supplied. It is about the first throttle 38 the internal combustion engine 10 regulated amount of air regulated. As long as there is no increased load requirement, the shut-off elements 32 . 36 closed.

Is now based on the current operating state in a step < 110 > a boost pressure request is provided which shows the current performance level of the compressor 22 the exhaust gas turbocharger 20 exceeds, is in a step < 120 > the additional compressor 26 activated and the shut-off 36 , which is preferably designed as a second throttle, opened. Thus, additional charge air through the auxiliary compressor 26 to be provided. In this case, the amount of additional charge air through the additional compressor 26 supplied power to be regulated. Here is the shut-off 32 , in particular a third throttle valve 34 , in the secondary air line 28 still closed, so no exhaust gas from the exhaust duct 12 through the secondary air line 28 towards an inlet 58 of the internal combustion engine 10 can flow.

Is in a process step < 130 > determines that the particulate filter 18 has reached a loading state in which a regeneration is necessary, which by a differential pressure measurement over the particulate filter 18 or one in the controller 52 stored loading model can be done, so in a step < 140 > an exhaust gas temperature in the area of the particle filter 18 determined. If this temperature is above a regeneration temperature of the particulate filter 18 , a regeneration of the particulate filter can be initiated. Otherwise, in a method step < 150 Measures for heating the exhaust gas, for example, an adjustment of the ignition angle of the internal combustion engine in the direction "late" initiated until the regeneration temperature of at least 550 ° C, preferably of at least 600 ° C is reached. In this case, the exhaust gas temperature by a temperature sensor on the exhaust duct 12 or be determined by a calculation model.

Is a load of the particulate filter 18 before, in which regeneration is necessary and is an exhaust gas temperature in the region of the particulate filter 18 reached above the regeneration temperature, then the shut-off 32 , in particular the third throttle 34 in one step < 160 > preferably completely open and the shut-off element 36 , so the second throttle, closed. By means of the second lambda probe 50 the oxygen content in the exhaust gas can be determined and the performance of the additional compressor 26 at stoichiometric operation of the internal combustion engine 10 be adjusted. Alternatively, the amount of air supplied via the secondary air line can also be achieved by a position of the shut-off element 32 be controlled or regulated. With increasing loading of the particulate filter 18 the maximum must be via the secondary air line 28 the particle filter 18 supplied amount of oxygen to be limited depending on the exhaust gas temperature to thermal damage of the particulate filter 18 to avoid by uncontrolled Rußabbrand. Is the particle filter 18 completely regenerated, the internal combustion engine becomes 10 in one step < 170 > Operated again in normal operation and the shut-off elements 32 and 36 closed again.

This behavior may be in a map in the controller 52 are stored and the desired amount of oxygen for the regeneration of the particulate filter 18 about the performance of the electric auxiliary compressor 26 be managed. Is now additionally during the regeneration of the particulate filter 18 a boost pressure requirement to the additional compressor 26 , so the second throttle valve or the shut-off 36 be opened to the compressor 24 the exhaust gas turbocharger 20 to assist during the boost pressure build-up. To control the desired oxygen concentration in the exhaust duct 12 upstream of the particulate filter 18 can the air mass flow through the secondary air line 28 by means of the third throttle 34 be adjusted. If the desired boost pressure can not be provided, the third throttle valve will be activated 34 closed and the regeneration of the particulate filter 18 interrupted or canceled. The method for regeneration of the particulate filter is in 2 shown in a flow chart.

When installing a suitable radiator, the secondary air line 28 with controlled opening of the second throttle 36 and the third throttle 34 also be used as exhaust gas recirculation line.

LIST OF REFERENCE NUMBERS

10

internal combustion engine

12

exhaust duct

14

turbine

16

catalyst

18

particulate Filter

20

turbocharger

22

Fresh air line

24

compressor

26

auxiliary compressor

28

Secondary air line

30

junction

32

shut-off

34

(third) throttle

36

(second) throttle

38

(first) throttle

40

first channel

42

second channel

44

third channel

46

Wastegate

48

first lambda probe

50

second lambda probe

52

control unit

54

signal line

56

outlet

58

inlet

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

• DE 10023022 A1 [0006]
• DE 10231107 A1 [0007]
• DE 19840629 A1 [0008]

Claims (10)

Device for exhaust aftertreatment of an internal combustion engine ( 10 ) with an exhaust gas turbocharger ( 20 ), with a turbine ( 14 ) of the exhaust gas turbocharger ( 20 ), which in an exhaust duct ( 12 ) of the internal combustion engine ( 10 ) and with one in a fresh air line ( 22 ) of the internal combustion engine ( 10 ) arranged compressors ( 24 ), with an electrically driven auxiliary compressor ( 26 ), which is independent of the exhaust gas turbocharger ( 20 ) Fresh air in the fresh air line ( 22 ) to the internal combustion engine ( 10 ) and with a secondary air line ( 28 ), which the additional compressor ( 26 ) with the exhaust duct ( 12 ) of the internal combustion engine ( 10 ), characterized in that the secondary air duct ( 28 ) upstream of a particulate filter ( 18 ) in the exhaust duct ( 12 ) of the internal combustion engine ( 10 ). Device for exhaust gas aftertreatment according to claim 1, characterized in that in the exhaust gas duct ( 12 ) in the flow direction of an exhaust gas of the internal combustion engine ( 10 ) through the exhaust duct ( 12 ) upstream of the particulate filter ( 18 ) a catalyst ( 16 ), wherein the secondary air line ( 28 ) downstream of the catalyst ( 16 ) and upstream of the particulate filter ( 18 ) in the exhaust duct ( 12 ) opens. Device for exhaust gas aftertreatment according to claim 1 or 2, characterized in that in the secondary air line ( 28 ) downstream of the auxiliary compressor ( 26 ) and upstream of a junction ( 30 ) of the secondary air line ( 28 ) in the exhaust duct ( 12 ) a shut-off element ( 32 ) for closing the secondary air line ( 28 ) or for throttling a flow through the secondary air line ( 28 ) is arranged. Aftertreatment device according to claim 3, characterized in that the shut-off element ( 32 ) a throttle valve ( 34 ). Device for exhaust aftertreatment according to one of claims 1 to 4, characterized in that the fresh air line ( 22 ) downstream of the compressor ( 24 ) into a first channel ( 40 ) and a second channel ( 42 ), where in the first channel ( 40 ) a throttle valve ( 38 ) for controlling the air supply of the internal combustion engine ( 10 ) and in the second channel ( 42 ) the auxiliary compressor ( 26 ) is arranged. Aftertreatment device according to claim 5, characterized in that the first channel ( 40 ) and the second channel ( 42 ) downstream of the throttle valve ( 38 ) and downstream of the auxiliary compressor ( 26 ) through a third channel ( 44 ), whereby in the third channel ( 44 ) another shut-off element ( 36 ) for closing the third channel ( 44 ) or to restrict a flow through the third channel ( 44 ) is arranged. Process for the regeneration of a particulate filter ( 18 ) in the exhaust duct ( 12 ) of an internal combustion engine ( 10 ), wherein the fresh air to the air supply of the internal combustion engine ( 10 ) by a compressor ( 24 ) provided by a turbine ( 14 ) of an exhaust gas turbocharger ( 20 ) of the internal combustion engine ( 10 ), and wherein an additional compressor ( 26 ) is provided, which is electrically driven and substantially independent of a speed or load of the internal combustion engine ( 10 ) allows a compression of the fresh air, characterized in that the of the auxiliary compressor ( 26 ) compressed fresh air via a secondary air line ( 26 ), which the additional compressor ( 26 ) with the exhaust duct ( 12 ), upstream of the particulate filter ( 18 ) in the exhaust duct ( 12 ) is blown. Method according to claim 7, characterized in that a shut-off device ( 32 ) in the secondary air line ( 38 ) is opened when, for the regeneration of the particulate filter ( 18 ) a sufficient temperature in the exhaust duct ( 12 ) is achieved. A method according to claim 7 or 8, characterized in that the amount of air in the regeneration of the particulate filter ( 18 ) by the additional compressor ( 26 ) or the shut-off valve ( 32 ) is adjusted so that in the exhaust duct ( 12 ) upstream of the particulate filter ( 18 ), an exhaust air ratio λ _A of 1.05 to 1.3 is set. Method according to one of claims 7 to 9, characterized in that at a simultaneous request by the auxiliary compressor ( 26 ) compressed fresh air for an additional fresh air supply of the internal combustion engine ( 10 ) and secondary air for the regeneration of the particulate filter ( 18 ) the fresh air supply for the internal combustion engine ( 10 ) Takes precedence over the provision of secondary air for the regeneration of the particulate filter ( 12 ) Has.

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