EP3211192B1 - Internal combustion engine with spark ignited engine and method for operating such a combustion engine - Google Patents

Description

The invention relates to an internal combustion engine, preferably a chargeable internal combustion engine with a spark ignition internal combustion engine, with the features according to the preamble of claim 1. Furthermore, the invention relates to a method for operating an internal combustion engine, preferably a chargeable internal combustion engine with a spark-ignition internal combustion engine, with the features according to In combustion processes in an internal combustion engine, in particular a spark ignition internal combustion engine, preferably used as a traction engine of a vehicle, soot particles, which are separated from a arranged in the exhaust system of the internal combustion engine particulate filter, in particular gasoline particulate filter, while driving from the exhaust gas. So that the exhaust gas backpressure before the particulate filter does not rise too far, the particulate filter is regenerated continuously or periodically, that is, the soot loading of the particulate filter is reduced by providing reaction conditions for a thermal oxidation of the soot with oxygen. For this purpose, a sufficiently high temperature in the particle filter with simultaneous supply of oxygen in the exhaust gas is necessary.
Since modern spark-ignited internal combustion engines are operated regularly without excess oxygen - lambda equal to 1, stoichiometric - or have good efficiencies, a separate procedure for regeneration is required. If the internal combustion engine is a traction engine of a vehicle, this is achieved by means of a special driving cycle. For regeneration, a temperature of more than 500 degrees Celsius in the particulate filter is required, the representation of which represents a major challenge in particular in an arrangement of the particulate filter in a portion of the exhaust system in the underbody of the vehicle, so with a relatively large distance to the engine of the internal combustion engine.

To bring oxygen into the exhaust system of an internal combustion engine with a 3-way catalyst and an auxiliary catalyst, it is for example from the document US 4,192,141 For the purpose of exhaust gas purification, it is known to control the reduction and oxidation conditions by supplying secondary air, in each case upstream of the catalysts, to the exhaust gas in the exhaust system as a function of the operating conditions of the internal combustion engine.

In order to introduce oxygen into the exhaust system with a particle filter of a spark-ignited internal combustion engine which can be charged by means of an exhaust gas turbocharger, it is for example in the document DE 10 2011 118 337 A1 described to introduce a portion of the charge air immediately before the particulate filter. For this purpose, a switchable from the air charge line downstream of the compressor switchable air line is provided which opens downstream of the turbine and optionally downstream of catalyst elements in the exhaust system, so that at sufficient boost pressure in the charge air line, a portion of the charge air passes directly into the exhaust system. The current through the air line can be controlled variably, in particular be shut off, by means of a valve.

From the document DE 10 2013 001 319 A1 goes out to operate an internal combustion engine with an exhaust tray, a first secondary air line and a second secondary air line, wherein alternately starting from the same compressed air source either through the first secondary air line or through the second secondary air line of the exhaust system secondary air is supplied. The first secondary air duct opens at several points in an exhaust manifold, wherein in each case a point in an individual exhaust gas line downstream of a combustion chamber of the internal combustion engine and upstream of an exhaust gas collection chamber of the exhaust manifold is located. The second secondary air line also opens downstream of the first secondary air line into the exhaust manifold, possibly into an exhaust gas collecting chamber in the exhaust manifold. The provision of a further secondary air line here serves to increase the efficiency of the reaction of the secondary air with the unburned fuel in a catalyst.

Object of the present invention is to provide an exhaust system of an internal combustion engine with spark-ignition internal combustion engine at a plurality of desired locations with secondary air.

This object is achieved by an internal combustion engine with the features according to claim 1 and / or by a method having the features according to claim 7.

An internal combustion engine according to the invention comprises a spark-ignited internal combustion engine, in particular a spark-ignited internal combustion engine, a fresh gas train, an exhaust system with at least one first exhaust aftertreatment device and at least one second exhaust aftertreatment device, in particular a particulate filter which is disposed downstream of the first exhaust aftertreatment device. The internal combustion engine further comprises a secondary air line with a secondary air pump branching from the fresh gas train, the secondary air line having a first branch opening into the exhaust system upstream of the first exhaust aftertreatment device and a second branch downstream of the first exhaust aftertreatment device and upstream of the particulate filter the exhaust system opens.

The secondary air pump may be a variable speed controlled and / or regulated operated secondary air pump. The secondary air pump can be driven variable speed, for example by means of an electric motor. The electric motor is preferably controlled by a microcontroller, which is in active and / or signal connection to an engine control unit of the internal combustion engine according to the invention.

According to the invention, the exhaust system immediately downstream of a plurality of combustion chambers of the internal combustion engine on a plurality of partial exhaust gas lines, which are further merged downstream at least partially to at least one exhaust manifold, wherein the first branch of the secondary air line in divides a plurality of sub-branches and opens each sub-branch at a first outlet of the sub-branch in a partial exhaust gas line.

Preferably, the at least one exhaust treatment device is arranged downstream of the first outlet in the partial exhaust gas line.

According to a second aspect (not according to the invention), the exhaust system immediately downstream of a plurality of combustion chambers of the internal combustion engine comprises a plurality of partial exhaust lines which are further merged downstream to an exhaust manifold, wherein the first branch of the secondary air line at a first outlet of the first branch in the exhaust manifold opens.

According to a further embodiment, the secondary air line has at least one valve for forwarding a volume flow conveyed through the secondary air line through the first branch and / or through the second branch.

In each case, a valve is preferably arranged in the first branch and in the second branch.

In particular, the secondary air line branches off from the fresh gas line upstream of a compressor arranged in the fresh gas line. Alternatively, the secondary air line branches off the fresh gas line downstream of the compressor.

In particular, at least the particle filter is arranged downstream of a turbine arranged in the exhaust system in the exhaust system.

Preferably, the internal combustion engine is a rechargeable internal combustion engine with at least one compressor in the fresh gas line and at least one turbine in the exhaust system. Preferably, the secondary air line branches off in front of the compressor (upstream of the compressor). Preferably, the first branch opens upstream (-wärts) of the turbine in the exhaust system and the second branch downstream (-wärts) of the turbine in the exhaust system. Alternatively, or in addition, the internal combustion engine in certain embodiments also be rechargeable by means of a mechanical or electrical compressor. The exhaust system may also include a turbine of another assembly, for example for energy recovery.

In the context of the invention is also a method for operating an internal combustion engine with a spark-ignited internal combustion engine, in particular a spark ignited spark internal combustion engine, a fresh gas train, an exhaust system with at least a first exhaust aftertreatment device and at least a second exhaust aftertreatment device, in particular a particle filter which downstream (-wärts) the first exhaust aftertreatment device is arranged, and a secondary air line with a secondary air pump, which branches off from the fresh gas train. In the method of the present invention, secondary air is introduced into the exhaust system upstream of the first exhaust aftertreatment device, and secondary air is introduced downstream of the first exhaust aftertreatment device and upstream of the particulate filter into the exhaust system.

1. a) durch nur den ersten Zweig oder durch nur den zweiten Zweig schaltbar ist oder
2. b) durch den ersten Zweig und durch den zweiten Zweig in einstellbaren Anteilen regelbar ist.

According to one development of the method, the secondary air line has a first branch, which opens into the exhaust system upstream of the exhaust gas after-treatment device at a first outlet of the first branch, and a second branch, which downstream of the exhaust aftertreatment device and upstream of the particulate filter at a second outlet of the second branch the exhaust system opens, wherein the secondary air line has at least one valve, which is for forwarding a through the secondary air line funded volume flow

1. a) is switchable by only the first branch or by only the second branch, or
2. b) is adjustable in adjustable proportions by the first branch and by the second branch.

In particular, the method is suitable for operating the internal combustion engine proposed here.

The comments on the internal combustion engine can be used to further characterize the process and vice versa.

In the case of a rechargeable internal combustion engine, in particular with the structural features described above, the rechargeable internal combustion engine is charged by means of the compressor.

In particular, the secondary air duct branches into a first branch and a second branch at a branch point. The secondary air pump is located in the secondary air line between the branch of the fresh gas line and the branch point. The first and the second branch are preferably closed fluid-tight. In a first group of embodiments, there is a 3-way valve at the branch point, so that secondary air can pass from the branch through the first branch to the exhaust system or from the branch through the second branch to the exhaust system, depending on the valve position. In a second group of embodiments, in each case a 2-way valve, with which the respective branch of the secondary air line can be closed, is located in the first and in the second branch.

Preferably, each of the valves can also be operated in intermediate positions so that adjustable portions of the volume flow conveyed through the secondary air line can be conveyed through the first branch and through the second branch (ie also simultaneously).

The internal combustion engine is preferably operated in a gasoline process or an Otto-Miller process, in particular ignited spark-ignited. The sparks may be generated by laser light or, preferably, by electrical discharge. The internal combustion engine is preferably operated stoichiometrically. The internal combustion engine is preferably a reciprocating internal combustion engine. The internal combustion engine may have a direct injection of fuel into the combustion chambers of the internal combustion engine or via a port injection of fuel into a suction pipe, preferably at a plurality of points (MPI).

With the invention, it is advantageously possible to introduce secondary air as required to a plurality, in particular to two desired locations in the exhaust system. Advantageous, in particular with regard to the necessary construction space and / or costs, is that only one secondary air pump is used together, which is thus used for both branches of the secondary air line.

Located downstream of the first orifice (first outlet) is a first exhaust treatment device (the exhaust aftertreatment device), the introduced secondary air may be utilized for exothermic reaction with exhaust constituents so that the first exhaust treatment device may be heated. For example, in a specific embodiment, a first catalyst stage, in particular a 3-way catalyst, can be heated in this way. Located downstream of the first orifice is a second exhaust treatment device (the particulate filter) having a storage function for certain exhaust constituents, the introduced secondary air may be utilized for exothermic reaction with the particular exhaust constituents such that the second exhaust treatment device may be discharged or regenerated. For example, in this way, in a specific embodiment, an Otto particle filter can be regenerated.

The internal combustion engine according to the invention preferably has a control unit which is designed such that a fuel-air ratio and / or one or more ignition angles and / or one or more injection times of the spark-ignition internal combustion engine can be controlled or regulated by these. Preferably, the control or regulation is carried out such that in the exhaust system after the admixing of the charge air via the secondary air line, a stoichiometric air-fuel ratio is achieved.

In contrast to a self-igniting internal combustion engine, in particular a diesel engine, in a rechargeable internal combustion engine according to the invention the intake manifold pressure / boost pressure, in particular to compensate for the poorer efficiency in the regeneration, and / or increases an air mass flow in the intake manifold. In addition, the exhaust gas mass flow is increased by the introduced via the secondary air line part of the charge air. In a self-igniting internal combustion engine, the boost pressure and the air mass flow are lowered in the regeneration phase.

In a preferred embodiment of the method according to the invention, the internal combustion engine, in particular during the regeneration of the particulate filter, operated at an operating point with partial load and / or with a substoichiometric fuel-air ratio.

It is particularly useful in the method according to the invention, the temperature in the exhaust system on the particulate filter to a value greater than 500 degrees Celsius, especially 560 degrees Celsius, and less than 1100 degrees Celsius, preferably greater than 580 degrees Celsius and less than 1000 degrees Celsius, to increase. The temperature of the exhaust system can be controlled, optionally regulated. The control or regulation can be carried out by the engine control unit. It may be based on a model of the temperature in the exhaust system and / or one or more measurements at various locations in the exhaust system.

Furthermore or alternatively, it is preferred in the method according to the invention to adjust one or more ignition angles and / or one or more injection times, compared to the operation at the same operating point without secondary air supply, to retard. In other words, one or more firing angles and / or one or more injection timings may be retarded compared to operation at the same operating point without secondary air supply.

Particularly advantageous and expedient in supercharged internal combustion engines according to the invention is, in the method according to the invention, to increase a boost pressure and / or an air mass flow to the spark-ignited internal combustion engine. In this way, the efficiency of the compressor can be optimized.

Fig. 1:

eine Darstellung einer ersten erfindungsgemäßen Ausführungsform einer Brennkraftmaschine;

Fig. 2:

eine Darstellung einer zweiten nicht erfindungsgemäßen Ausgestaltung einer Brennkraftmaschine.

The internal combustion engine according to the invention may be an internal combustion engine operated with gasoline as fuel. Alternatively, the internal combustion engine according to the invention may be an internal combustion engine operated with gas, preferably methane gas or CNG, as a fuel. In one group of embodiments, it is a bivalent, in particular alternately, operable with the fuels gasoline and gas internal combustion engine. In a bivalent internal combustion engine is prefers the gasoline injected directly into the combustion chambers and blown the gas in several places in the intake manifold (MPI injection).
The internal combustion engine according to the invention is preferably part of a drive unit of a vehicle, in particular of a trackless land vehicle. In particular, it may be the only drive source or else part of a hybrid drive, for example in combination with one or more electric machines. Preferably, the vehicle is a passenger car or a commercial vehicle, wherein a particulate filter is arranged in an underbody of the vehicle. The particulate filter is preferably in other words remote from the engine, that is not in the engine compartment, especially not on the engine, arranged, but z. B. at a distance of at least 75 cm [centimeters] to the combustion chambers of the internal combustion engine. One of the advantages of arranging the particulate filter in the underbody is to achieve the lowest possible exhaust back pressure for the internal combustion engine. In addition, more space is available for the particulate filter. This can be used for a larger package in comparison to the installation between the underbody and combustion chambers of the internal combustion engine, so a close-coupled installation. By adapting to a larger space and a lower volume flow advantageously in particle filter can be achieved. For a particle filter remote from the engine, the invention makes it possible to provide the oxygen concentration for its regeneration.
The invention and the technical environment will be explained in more detail with reference to FIGS. The figures show particularly preferred embodiments, to which the invention is not limited. In particular, it should be noted that the figures and in particular the illustrated proportions are only schematic. Like reference numerals designate like objects. Show it:

Fig. 1:

a representation of a first embodiment of an internal combustion engine according to the invention;

Fig. 2:

an illustration of a second non-inventive embodiment of an internal combustion engine.

The FIG. 1 shows a first embodiment of an internal combustion engine 1, which can be charged by means of a turbocharger consisting of an exhaust gas turbine 19 and a compressor 18 Aufladegruppe (exhaust gas turbocharger). A non-chargeable internal combustion engine 1, a suction engine, can, except for the then missing Aufladegruppe the same topology as in FIG. 1 have shown. The internal combustion engine 1 in this embodiment is a traction machine of a trackless land vehicle and thus integrated into the land vehicle.

The in the FIG. 1 illustrated embodiment has a spark-ignition of electrical discharges spark-ignited internal combustion engine 1, which operates with a gasoline combustion process or Otto-Miller combustion process. The internal combustion engine 2 is a reciprocating piston engine with, for example, four cylindrical combustion chambers 11. The spark-ignited internal combustion engine 2 is supplied with air through a fresh gas line 3. From the air first non-gaseous impurities are separated in an air filter 34 (Lufi). The air is compressed by means of a compressor 18 of the turbocharger charge group. It passes a throttle valve 24 and enters a suction tube. Here in the FIG. 1 not shown in the drawing, such an embodiment, a charge air cooler, in particular a suction pipe integrated intercooler, have.

From the combustion chambers 11 exhaust gas is discharged into the exhaust system 4, first in an exhaust manifold. The exhaust manifold has individual (partial) exhaust pipes 12, which extend from the individual exhaust valves of the four combustion chambers 11 to a (exhaust) manifold 13. In other words, the exhaust manifold combines the effluent exhaust gas over individual floods to a total exhaust gas flow. The exhaust gas is first conducted in the exhaust system 4 via a turbine 19 of the turbocharger charge group, which drives the compressor 18. The expanded exhaust gas passes downstream of the turbine 19 into a first exhaust aftertreatment device 5, a catalyst, in particular a three-way catalyst KAT. The first exhaust aftertreatment device 5 may be located close to the engine, in particular on the engine or in the engine compartment, so that the heat from the burns in the Combustion chambers 11 can be used for heating the first exhaust aftertreatment device 5.

Downstream of the first exhaust aftertreatment device 5 is a second exhaust aftertreatment device 6 with a storage function, specifically preferred for soot particles, in particular an Ottopartikelfilter 6 OPF. In this embodiment, the second exhaust aftertreatment device is disposed in the underbody of the land vehicle. After passage of the Ottopartikelfilters 6, the exhaust gas enters the environment of the internal combustion engine. 1

According to the invention has in the FIG. 1 shown embodiment via a secondary air line 7, which branches off upstream of the compressor 18 and downstream of the air filter 34 from the fresh gas line 3. The secondary air line 7 has a secondary air pump 8, whose impeller promotes air through the secondary air line 7 to the exhaust system 4. Downstream of the secondary air pump 8, the secondary air duct 7 branches off into a first branch 9 and into a second branch 10. The first branch 9 opens into the exhaust system 4 upstream of the turbine 19, while the second branch 10 flows downstream of the first exhaust aftertreatment device 5 and upstream of the second exhaust aftertreatment device 6 opens into the exhaust system 4.

In the rechargeable internal combustion engine 1, the first branch 9 of the secondary air line 7 can open or end in an exhaust manifold of the exhaust system 4 at one or more discharge points (first outlets 15). Particularly preferably, the exhaust manifold is integrated in the cylinder head. If it is a cooled at certain operating points of the internal combustion engine 1 exhaust manifold, it is advantageous in the context of the invention, when introducing secondary air into the exhaust system 4 to reduce the cooling of the exhaust gas or omit altogether. One advantage of an exothermic reaction as far upstream in the exhaust system 4 is, inter alia, that the risk of uncontrolled combustion of the particular rich exhaust gas in sensitive components of the exhaust system 4, such as catalysts, reduced, preferably avoided. In connection with turbines 19 in the exhaust system 4 additional exhaust enthalpy for the turbine 19 can be provided in an advantageous manner.

In the present first embodiment, the exhaust system 4 immediately downstream of a plurality of combustion chambers 11 of the internal combustion engine 2, a plurality of partial exhaust gas lines 12, which are further merged downstream to an exhaust manifold 13, wherein the first branch 9 of the secondary air duct 7 is divided into a plurality of sub-branches 14 and each partial branch 14 opens at a first outlet 15 of the partial branch 14 into a partial exhaust gas line 12.

Both in the first branch 9 and in the second branch 10 of the secondary air line 7 is in each case a secondary air valve (valve 16). The respective secondary air valve 16 can be opened or closed, so that the fluid connection can be interrupted or produced in the exhaust system 4.

In the FIG. 1 a series of along the fresh gas line 3 and the exhaust system 4 arranged measuring sensors or in the secondary air line 7 is shown. These are in signal and / or control and / or operative connection (not shown in the drawing) with an engine control unit 22. Based on a selection or all measured by the measuring sensors variables operating conditions, operating state parameters or operating conditions of the internal combustion engine 1 can be diagnosed. All or a selection of the measured variables can furthermore be used for the control and / or regulation of the internal combustion engine 1 or of assemblies / parts of the internal combustion engine 1. In particular, measured variables for the control and / or regulation of the regeneration of the second exhaust gas aftertreatment device 6, in particular of the Otto particle filter 6, can be used.

In Frischgasstrang 3 is downstream of the compressor 18 and upstream of the throttle valve 24, a first combined pressure and temperature sensor 23. Downstream of the throttle valve 24 and upstream of the combustion chambers 11 is a second combined pressure and temperature sensor 25 in the fresh gas line 3. In the exhaust system downstream of the mouth (first outlets 15) of the first branch 9 of the secondary air duct 7 and upstream of the turbine 19 is a pressure sensor (third sensor 26), a so-called p3 sensor. Downstream of turbine 19 and upstream first exhaust aftertreatment device 5 is a first linear lambda probe 27 in the exhaust system 4. Downstream of the mouth (second outlet 21) of the second branch 10 of the secondary air line 7 and upstream of the second exhaust aftertreatment device 6, in particular the Ottopartikelfilters 6, there is a second linear lambda Probe 28 and a (first) temperature sensor 29 (T _v OPF). Downstream of the second exhaust aftertreatment device 6, in particular of the Otto particle filter 6, there are a jump lambda probe (third lambda probe 30) and a (second) temperature sensor 31 (T _n OPF) in the exhaust system 4.
For the specific case that the second exhaust aftertreatment device 6 is a (Otto) particulate filter 6, the pressure difference / pressure drop p _rel to OPF is measured between a point upstream of the Ottopartikelfilters 6 and another point downstream of the Ottopartikelfilters 6. For this purpose, a differential pressure sensor Δp _OPF sensor (fourth sensor 32) is used. On the basis of the measured via the particulate filter 6 pressure difference can be decided in particular whether a regeneration of the gasoline particulate filter 6 is necessary, and a regeneration are initiated.
In the secondary air line 7 is located downstream of the secondary air pump 8 and upstream of the branch point in the first and second branches 9, 10, a pressure sensor (fifth sensor 33).

Fig. 2 shows a representation of a second non-inventive embodiment of an internal combustion engine 1. The comments on Fig. 1 will be referred. Here too, the secondary air line 7 has two valves 16 for the forwarding of a volume flow 17 conveyed through the secondary air line 7 through the first branch 9 and / or through the second branch 10. Here, the secondary air line 7 branches off the fresh gas line 3 downstream of the compressor 18. The first branch 9 opens here at a single first outlet 15 into the exhaust manifold 13. The partial exhaust gas lines 12 are merged upstream of the first outlet 15 to an exhaust manifold 13. Secondary air 20 is conveyed into the exhaust system 4 upstream of the particulate filter 6 and downstream of the exhaust gas treatment unit 5 via the second branch 10.

LIST OF REFERENCE NUMBERS

1

Internal combustion engine

2

internal combustion engine

3

Fresh gas line

4

exhaust system

5

exhaust aftertreatment device

6

particulate Filter

7

Secondary air line

8th

Secondary air pump

9

first branch

10

second branch

11

combustion chamber

12

Part exhaust pipe

13

Exhaust manifold

14

subbranch

15

first outlet

16

Valve

17

flow

18

compressor

19

turbine

20

secondary air

21

second outlet

22

Engine control unit

23

first sensor

24

throttle

25

second sensor

26

third sensor

27

first lambda probe

28

second lambda probe

29

first temperature sensor

30

third lambda probe

31

second temperature sensor

32

fourth sensor

33

fifth sensor

34

air filter

Claims (8)

1. Internal combustion engine (1) having an applied-ignition combustion motor (2), having a fresh-gas tract (3), having an exhaust-gas system (4) with at least one exhaust-gas aftertreatment device (5) and at least one particle filter (6) arranged downstream of the exhaust-gas aftertreatment device (5), and having a secondary air line (7) with a secondary air pump (8), which secondary air line branches off from the fresh-gas tract (3), wherein the secondary air line (7) has a first branch (9), which opens into the exhaust-gas system (4) upstream of the exhaust-gas aftertreatment device (5), and has a second branch (10), which opens into the exhaust-gas system (4) downstream of the exhaust-gas aftertreatment device (5) and upstream of the particle filter (6), wherein the exhaust-gas system (4) has, directly downstream of a multiplicity of combustion chambers (11) of the combustion motor (2), a multiplicity of partial exhaust lines (12) which, further downstream, are at least partially merged to form at least one collective exhaust-gas line (13), characterized in that the first branch (9) of the secondary air line (7) splits into multiple partial branches (14), and each partial branch (14) opens, at a first outlet (15) of the partial branch (14), into a partial exhaust line (12) .
2. Internal combustion engine (1) according to Patent Claim 1, wherein the at least one exhaust-gas aftertreatment device (5) is arranged in the partial exhaust line (12) downstream of the first outlet (15) .
3. Internal combustion engine (1) according to one of the preceding patent claims, wherein the secondary air line (7) has at least one valve (16) for conducting a volume flow (17) conveyed through the secondary air line (7) onwards through the first branch (9) and/or through the second branch (10).
4. Internal combustion engine (1) according to Patent Claim 3, wherein in each case one valve (16) is arranged in the first branch (9) and in the second branch (10).
5. Internal combustion engine (1) according to one of the preceding patent claims, wherein the secondary air line (7) branches off from the fresh-gas tract (3) upstream of a compressor (18) arranged in the fresh-gas tract (3).
6. Internal combustion engine (1) according to one of the preceding patent claims, wherein at least the particle filter (6) is arranged in the exhaust-gas system (4) downstream of a turbine (19) arranged in the exhaust-gas system (4).
7. Method for operating an internal combustion engine (1) having an applied-ignition combustion motor (2), having a fresh-gas tract (3), having an exhaust-gas system (4) with at least one exhaust-gas aftertreatment device (5) and at least one particle filter (6) arranged downstream of the exhaust-gas aftertreatment device (5), and having a secondary air line (7) with a secondary air pump (8), which secondary air line branches off from the fresh-gas tract (3), in which method secondary air (20) is introduced into the exhaust-gas system (4) upstream of the exhaust-gas aftertreatment device (5), and secondary air (20) is introduced into the exhaust-gas system (4) downstream of the exhaust-gas aftertreatment device (5) and upstream of the particle filter (6); wherein the secondary air line (7) has a first branch (9), which opens into the exhaust-gas system (4) upstream of the exhaust-gas aftertreatment device (5), and has a second branch (10), which opens into the exhaust-gas system (4) downstream of the exhaust-gas aftertreatment device (5) and upstream of the particle filter (6) at a second outlet (21) of the second branch (10); wherein the exhaust-gas system (4) has, directly downstream of a multiplicity of combustion chambers (11) of the combustion motor (2), a multiplicity of partial exhaust lines (12) which, further downstream, are at least partially merged to form at least one collective exhaust-gas line (13), characterized in that the first branch (9) of the secondary air line (7) splits into multiple partial branches (14), and each partial branch (14) opens, at a first outlet (15) of the partial branch (14), into a partial exhaust line (12).
8. Method according to Patent Claim 7, wherein the secondary air line (7) has at least one valve (16) which

   a) is switchable so as to conduct a volume flow conveyed through the secondary air line (7) onward through only the first branch (9) or through only the second branch (10), or

   b) is controllable so as to conduct a volume flow conveyed through the secondary air line (7) onward through the first branch (9) and through the second branch (10) in adjustable fractions.

Images