DE102016212007A1 - Control of an exhaust gas temperature - Google Patents

Abstract

A method is provided for controlling a temperature, particularly the temperature of a particulate filter and the exhaust gas, in an exhaust tract of an internal combustion engine, optionally by passing the exhaust gas flow through a turbine and / or bypass line of the turbine to adjust as required, e.g. if regeneration of the particulate filter is required to provide exhaust gas at different temperatures at the particulate filter. Furthermore, an arrangement for carrying out the method is provided.

Description

The invention relates to a method for controlling an exhaust gas temperature in an exhaust gas tract of an internal combustion engine.

Internal combustion engines produce soot particles during the combustion of fuel, especially when burning diesel fuel. Soot particles mainly consist of soot and unburned hydrocarbons. For purifying exhaust gas of an internal combustion engine filters are used, which reduce the amount of soot particles contained in the exhaust gas. The corresponding filters are therefore also referred to as particle filters. The soot particles collected in a particulate filter are removed by burning, whereby the particulate filter is regenerated. Regular regeneration of the filter is necessary as increasing soot loading results in high exhaust backpressure which hinders exhaust emissions.

However, the resulting from the burning of the soot particles temperatures can lead to thermal stress, so that too high temperatures should be avoided, which arise especially at too high soot loadings of the filter. Thermal stress can e.g. lead to cracks in the material of the filter, which lower its filtration efficiency.

During normal operation of the internal combustion engine, the exhaust gas temperature is often too low to allow for spontaneous filter regeneration. A temperature sufficient to start the regeneration is often made possible by late fuel injections into the internal combustion engine or by fuel injections into the exhaust tract. During regeneration, the temperature must be maintained by appropriate measures.

The task is to make fuel consumption efficient during regeneration.

This object is achieved by a method having the features of claim 1. Further advantageous embodiments and embodiments of the invention will become apparent from the dependent claims and claims, the figures and the embodiments.

• – S1) Erfassen der Abgastemperatur im laufenden Betrieb der Brennkraftmaschine, während dem das Kombinationsventil derart eingestellt ist, dass mindestens ein Teil des Abgases durch die erste Turbine geleitet wird,
• – S2) Ermitteln der Partikelbeladung des Partikelfilters,
• – S3) Einstellen des Kombinationsventils derart, dass ein größerer Prozentsatz des Abgases durch die Bypassleitung als durch die erste Turbine geleitet wird, wenn die Partikelbeladung des Partikelfilters eine Regeneration erforderlich macht,
• – S4) Einstellen des Kombinationsventils derart, dass ein größerer Prozentsatz des Abgases durch die erste Turbine als durch die Bypassleitung geleitet wird, wenn ein vorgegebener erster Schwellenwert der Temperatur am Partikelfilter überschritten wird.

A first aspect of the invention relates to a method for controlling an exhaust gas temperature in an arrangement with an internal combustion engine, an intake tract, an exhaust tract, at least a first turbine arranged in the exhaust tract, wherein the first turbine is coupled to a generator, wherein upstream of the first turbine first bypass line branches off the exhaust tract and downstream of the first turbine, the first bypass line opens into the exhaust tract, and wherein a combination valve is arranged in the region of the branch of the bypass line from the exhaust tract, which is formed, both the exhaust tract and the first bypass line for a flow through a fluid medium to release or lock in various degrees, a particulate filter, at least one temperature sensor and a control device,
with the steps:

• - S1) detecting the exhaust gas temperature during operation of the internal combustion engine, during which the combination valve is set such that at least a portion of the exhaust gas is passed through the first turbine,
• - S2) determining the particle load of the particulate filter,
• - S3) adjusting the combination valve such that a greater percentage of the exhaust gas is directed through the bypass line than through the first turbine when particulate loading of the particulate filter requires regeneration,
• - S4) adjusting the combination valve such that a greater percentage of the exhaust gas is passed through the first turbine than through the bypass line when a predetermined first threshold temperature of the particulate filter is exceeded.

In the first turbine, the heat of the exhaust gas is converted into mechanical energy, which in turn can be converted into electrical energy. The advantage of the method, especially for starting a regeneration, is that less fuel has to be expended to start the regeneration. Furthermore, advantageously, the time required for complete regeneration can be minimized.

Preferably, the combination valve is adjusted in step S3 so that a greater percentage of the exhaust gas is passed through the bypass line than through the first turbine, when a predetermined second threshold value is fallen below the temperature at the particulate filter. Advantageously, less additional energy must be expended in the form of fuel in order to bring the temperature of the particulate filter to a level that starts the regeneration of the particulate filter. It is particularly preferred if the combination valve is set to start the regeneration so that the entire exhaust gas flow is passed through the bypass line.

Furthermore, it is preferred if the temperature of the particulate filter is controlled during the regeneration such that when a predetermined threshold value is exceeded, the combination valve is set so that in step S4 of entire exhaust gas flow is passed through the first turbine. This advantageously avoids that the temperature of the particulate filter during regeneration reaches a level in which the material of the particulate filter is exposed to a thermal load, which leads to premature thermal aging of the material.

Preferably, the generator is coupled to a battery. In this way, electrical energy can advantageously be obtained in the method and the heat supply in the direction of a particle filter arranged downstream of the first turbine can be controlled.

Preferably, the battery is coupled to at least one compressor in the intake tract. In this way, the recovered electrical energy can be used advantageously for compressing the charge air for the internal combustion engine.

Preferably, the controller implements an intelligent algorithm for storing the energy in the battery that uses information that allows the prediction of a need for certain temperature control actions.

A second aspect of the invention relates to an arrangement adapted to carry out the method according to the invention, comprising an internal combustion engine, an intake tract, an exhaust tract, at least one first turbine arranged in the exhaust tract, the first turbine being coupled to a generator, upstream of the first turbine Turbine branches off a first bypass line from the exhaust tract and downstream of the first turbine, the first bypass line opens into the exhaust tract, and wherein a combination valve is disposed in the region of the branch of the first bypass line, which is formed, both the exhaust tract and the first bypass line for a flow Release or lock a fluid medium in various degrees, a particulate filter, at least one temperature sensor and a control device. The advantages of the arrangement correspond to those of the method according to the invention.

A third aspect of the invention relates to a motor vehicle with an inventive arrangement.

The invention will be explained in more detail with reference to FIGS. Show it

1 a schematic representation of an exemplary embodiment of an inventive arrangement.

2 a schematic representation of another exemplary embodiment of an inventive arrangement.

3 a flow diagram of an exemplary embodiment of a method according to the invention.

In 1 is an embodiment of an arrangement according to the invention 1 shown. The order 1 includes an internal combustion engine 2 , The internal combustion engine 2 is preferably a self-igniting internal combustion engine, but may also be spark ignited. The internal combustion engine 2 is schematically exemplary with three cylinders 2a Of course, it may also have only one, two, four or a larger number of cylinders.

The internal combustion engine 2 is with an intake tract 3 for supplying charge air and with an exhaust tract 4 connected to the discharge of exhaust gas. The order 1 has a first turbine 5 on. The first turbine 5 is with a generator 6 coupled to generate electrical power. The generator 6 is with a battery 7 coupled, which is adapted to store the generated electric current. The battery is equipped with an electrically operable first compressor 8th connected, so that by means of the first turbine 5 generated electrical energy for operating the first compressor 8th can be used.

Upstream of the first turbine 5 branches a first bypass line 9 from the exhaust tract 4 off, the downstream of the first turbine 5 again in the exhaust tract 4 empties. The first bypass line 9 is formed, at least part of the exhaust gas around the first turbine 5 to guide around. In the area of the branch is a combination valve 10 in the exhaust tract 4 arranged. The combination valve 10 is trained, both the exhaust tract 4 as well as the first bypass line 9 to release or block for a flow of exhaust gas in various degrees.

Downstream of the mouth of the first bypass line 9 in the exhaust tract 4 is a particle filter 11 arranged. The particle filter 11 is designed to filter particles, especially soot particles, from the exhaust gas stream.

In the exhaust tract 4 is a first temperature sensor 12a directly on the particle filter 11 arranged. Other temperature sensors 12b and 12c are upstream of the combination valve 10 or the first turbine 5 arranged. The temperature sensors 12a . 12b . 12c are with a control device 13 connected. The control device 13 is still with the combination valve 10 connected. The control device 13 is designed accordingly, namely measured temperature values from the temperature sensors 12a . 12b . 12c to receive, evaluate this and set the combination valve for controlling the exhaust gas temperature.

Compared to 1 is in the arrangement 1 according to 2 in addition a second turbine 14 in the exhaust tract 4 arranged, which is an exhaust gas turbine, which has a mechanical shaft directly with a second compressor 15 is coupled. The second turbine 2 has a second bypass line, also called wastegate line 16 to designate in which a wastegate valve 17 is arranged. Furthermore, in the exhaust system 4 downstream of the first turbine 5 an exhaust aftertreatment device 18 arranged.

In a method for controlling an exhaust gas temperature in the exhaust tract 4 the internal combustion engine 2 , and thus the regeneration of the particulate filter 11 , In a first step S1, the temperatures of the particulate filter and the exhaust gas temperature during operation of the internal combustion engine 2 detected. Here is the combination valve 10 set such that at least a portion of the exhaust gas through the first turbine 5 is directed. The temperature at the particle filter 11 is by means of the temperature sensor 12a and the temperature of the exhaust gas by means of the temperature sensors 12b and 12c recorded and sent to the controller 13 transmitted. The control device 13 evaluates the temperature signal and sends a control signal to the combination valve 10 ,

Parallel to the temperature measurements in a second step S2, there is a need for regeneration of the particulate filter 11 determined. A regeneration of the particulate filter 11 is necessary when loading the particulate filter 11 exceeds a permissible limit. The loading of the particulate filter, for example, by pressure measurements on the particulate filter 11 determined. For starting and during the regeneration, the entire exhaust gas flow through the bypass line can 9 be directed.

If a predetermined first threshold value W1 of the temperature is exceeded, which is a limit in relation to the tolerable heat load of the particulate filter 11 during a regeneration, in a third step S3, the combination valve 10 set such that a greater percentage of the exhaust gas through the first turbine 5 as through the bypass line 9 is directed. If necessary, the entire exhaust gas flow through the first turbine 5 be directed. In this case, a larger part of the exhaust gas to drive the first turbine 5 passed the generator 6 drives to generate electrical energy. The generated electrical energy gets in the battery 7 stored, for example, at a later date the compressor 8th drive.

If a predetermined second threshold value W2 of the temperature is exceeded, in a fourth step S4, the combination valve 10 set such that a greater percentage of the exhaust gas through the bypass line 9 as by the first turbine 5 is directed. The second threshold W2 represents a limit of the temperature above which hot exhaust gas is required to increase the fuel consumption used to raise the temperature at the particulate filter 11 for starting and maintaining a regeneration of the particulate filter 11 in the exhaust tract 4 is introduced to restrict.

Is the regeneration of the particulate filter 11 ends, the process is performed again from step S1.

With the arrangement according to 2 the procedure is carried out analogously. Here's the second turbine 14 is associated with a turbocharger, is to provide exhaust gas with the highest possible temperature, ie to start and support a regeneration of the particulate filter 11 , Exhaust gas at least partially through the Wastegateleitung 16 directed. Also, the exhaust aftertreatment device 18 is used in calculating the control of the exhaust gas around the turbines 5 and 14 considered, because the exhaust gas and heat to the exhaust aftertreatment device 18 emits.

LIST OF REFERENCE NUMBERS

1

 arrangement

2

 Internal combustion engine

2a

 cylinder

3

 intake system

4

 exhaust tract

5

 first turbine

6

 generator

7

 battery

8th

 first compressor

9

 first bypass line

10

 combination valve

11

 particulate Filter

12

 temperature sensor

13

 control device

14

 second turbine

15

 second compressor

16

 second bypass line

17

 Wastegate valve

18

 exhaust treatment device

Claims (9)

Method for controlling an exhaust gas temperature in an arrangement ( 1 ) with an internal combustion engine ( 2 ), an intake tract ( 3 ), an exhaust tract ( 4 ) at least one first in the exhaust tract ( 4 ) arranged first turbine ( 5 ), wherein the first turbine with a generator ( 6 ), upstream of the first turbine ( 5 ) a first bypass line ( 9 ) from the exhaust tract ( 4 ) branches off and downstream of the first turbine ( 5 ) the first bypass line ( 9 ) back into the exhaust tract ( 4 ), and wherein a combination valve ( 10 ) in the region of the branch of the first bypass line ( 9 ) from the exhaust tract ( 4 ) is arranged, which is formed, both the exhaust gas tract ( 4 ) as well as the first bypass line ( 9 ) for a flow of a fluid medium to release or lock in different degrees, a particulate filter ( 11 ), at least one temperature sensor ( 12a ) and a control device ( 13 ), with the steps: - S1) Detecting the exhaust gas temperature during operation of the internal combustion engine ( 2 ), during which the combination valve ( 10 ) is set such that at least a portion of the exhaust gas through the first turbine ( 5 ), S2) determining the particle load of the particulate filter ( 11 ), - S3) Setting the combination valve ( 10 ) such that a larger percentage of the exhaust gas through the bypass line ( 9 ) than through the first turbine ( 5 ) is passed when the particle load of the particulate filter ( 11 ) requires regeneration, - S4) setting the combination valve ( 10 ) such that a larger percentage of the exhaust gas through the first turbine ( 5 ) than through the bypass line ( 9 ), when a predetermined first threshold value of the temperature at the particulate filter ( 11 ) is exceeded. Method according to claim 1, wherein the combination valve ( 10 ) is set in step S3 so that a larger percentage of the exhaust gas through the bypass line ( 9 ) than through the first turbine ( 5 ) is passed when a predetermined second threshold of the temperature at the particulate filter ( 11 ) is fallen below. Method according to claim 2, wherein the combination valve ( 10 ) is set to start the regeneration of the particulate filter so that the entire exhaust gas flow through the bypass line ( 9 ). Method according to one of the preceding claims, wherein the temperature of the particulate filter ( 11 ) is controlled during the regeneration such that when a predetermined threshold value is exceeded, the combination valve ( 10 ) is set so that in step S4 the entire exhaust gas flow through the first turbine ( 5 ). Method according to one of the preceding claims, wherein the generator ( 6 ) with a battery ( 7 ) is coupled. Method according to one of the preceding claims, wherein the battery ( 7 ) with at least one compressor ( 8th ) in the intake tract ( 3 ) is coupled. Method according to one of the preceding claims, wherein in the control device ( 13 ) an intelligent algorithm for storing the energy in the battery ( 7 ) implementing information that allows the prediction of a need for certain temperature control actions Arrangement ( 1 ) configured to carry out a method according to any one of claims 1-7, comprising an internal combustion engine ( 2 ), an intake tract ( 3 ), an exhaust tract ( 4 ), at least one first in the exhaust tract ( 4 ) arranged first turbine ( 5 ), the first turbine ( 5 ) with a generator ( 6 ), upstream of the first turbine ( 5 ) a bypass line ( 9 ) from the exhaust tract ( 4 ) branches off and downstream of the first turbine ( 5 ) the bypass line ( 9 ) again in the exhaust tract ( 4 ), and wherein a combination valve ( 10 ) in the region of the branch of the first bypass line ( 9 ) from the exhaust tract ( 4 ) is arranged, which is formed, both the exhaust gas tract ( 4 ) as well as the first bypass line ( 9 ) for a flow of a fluid medium in different degrees to release or lock a particle filter ( 11 ), at least one temperature sensor ( 12a ) and a control device ( 13 ). Motor vehicle with an arrangement according to claim 8.

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