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In an internal combustion engine having a compressor in its induction system which has a compressor wheel rotatably mounted in an intake duct combustion air compressor, whereby the combustion air is compressed to an increased boost pressure, and an auxiliary duct which opens into the compressor inta

In an internal combustion engine having a compressor in its induction system which has a compressor wheel rotatably mounted in an intake duct combustion air compressor, whereby the combustion air is compressed to an increased boost pressure, and an auxiliary duct which opens into the compressor intake duct, an adjustable blocking element being arranged in the compressor intake duct upstream of the compressor wheel and an adjustable swirl device being arranged in an opening region of the auxiliary duct, and an NOx storage catalytic converter being disposed in the exhaust gas system, the blocking device and the swirl device are adjustable so as to generate an air fuel ratio with an excess of fuel, and, at the same time a propulsive swirl is applied to the compressor wheel when the blocking element is moved to a position in which air supply to the compressor intake duct is restricted.

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What is claimed is: 1. A method for operating an internal combustion engine having an air induction and an exhaust gas system, a compressor with a compressor housing and a compressor wheel (102) rotatably mounted in the compressor housing disposed in the induction system for compressing combustion

What is claimed is: 1. A method for operating an internal combustion engine having an air induction and an exhaust gas system, a compressor with a compressor housing and a compressor wheel (102) rotatably mounted in the compressor housing disposed in the induction system for compressing combustion air to an increased boost pressure, the compressor housing having an intake duct and an auxiliary duct (115) extending to the compressor intake duct (105) and being in communication therewith via an opening region (116) formed adjacent the compressor wheel (102), an adjustable blocking element (109) arranged in the compressor intake duct (105) upstream of the compressor wheel (102), an adjustable swirl device (114, 117) arranged in the opening region (116) of the auxiliary duct (115) into the compressor intake duct (105), and an NOx storage catalytic converter (12) arranged in the exhaust gas system, the swirl device (114, 117) being movable to a position in which combustion air is directed onto the compressor wheel so as to produce a propulsive swirl, and simultaneously the blocking element (109) being movable to a position in which the air supply to the compressor intake duct (105) is restricted in order to generate an air fuel ratio (λ) having a relative surplus of fuel, said method comprising the steps of restricting the air supply to the compressor wheel (102), and applying to the compressor wheel (102) simultaneously a propulsive swirl of combustion air while keeping the fuel supply at least approximately constant in order to reduce NOx emissions. 2. An internal combustion engine having an air induction and an exhaust gas system, a compressor with a compressor housing and a compressor wheel (102) rotatably mounted in the compressor housing disposed in the induction system for compressing combustion air to an increased boost pressure, the compressor housing having an intake duct and an auxiliary duct (115) extending to the compressor intake duct (105) and being in communication therewith via an opening region (116) formed adjacent the compressor wheel (102), an adjustable blocking element (109) arranged in the compressor intake duct (105) upstream of the compressor wheel (102), an adjustable swirl device (114, 117) arranged in the opening region (116) of the auxiliary duct (115) into the compressor intake duct (105), and an NOx storage catalytic converter (12) arranged in the exhaust gas system, the swirl device (114, 117) being movable to a position in which combustion air is directed onto the compressor wheel so as to produce a propulsive swirl, and simultaneously the blocking element (109) being movable to a position in which the air supply to the compressor intake duct (105) is restricted in order to generate an air fuel ratio (λ) having a relative surplus of fuel. 3. The internal combustion engine as claimed in claim 2, wherein the compressor (5) is part of an exhaust gas turbocharger (2) having an exhaust gas turbine (3) in the exhaust gas system (18), the compressor wheel (102) being coupled to the turbine wheel. 4. The internal combustion engine as claimed in claim 3, wherein the exhaust gas turbine (3) has a variable guide vane structure (4) in order to variably set the effective turbine inlet cross section. 5. The internal combustion engine as claimed in claim 3, wherein the NOx storage catalytic converter (12) is arranged downstream of the exhaust gas turbine (3). 6. The internal combustion engine as claimed in 2, wherein a slide sleeve (114) is axially movably supported in the intake duct (105) in spaced relationship form the intake duct wall so as to form the auxiliary duct therebetween and the blocking element (109) in the compressor (5) is movable so as to engage and move the slide sleeve (114) relative to the swirl device (117). 7. The internal combustion engine as claimed in claim 6, wherein the slide sleeve (114) is spring-loaded into one of its end positions and the blocking element (109) acts on the slide sleeve (114) counter to the spring direction. 8. The internal combustion engine as claimed in claim 6, wherein, in a first movement segment of the adjusting movement, only the blocking element (109) is displaced, and in a subsequent second movement segment, the slide sleeve (114, 117) is displaced by the blocking element (109). 9. The internal combustion engine as claimed in claim 6, wherein the adjusting movement of the blocking element (109) is an axial movement in the direction of the axis of the compressor wheel (102). 10. The internal combustion engine as claimed in claim 6, wherein the swirl device (117) comprises the axial slide sleeve (114) and a swirl grate (117) disposed in the area of the opening (116) of the auxiliary duct (115), the axial slide sleeve (114) being movable between an open position which unblocks the swirl grate (117) and a choking position which reduces the flow cross section through the swirl grate (117). 11. The internal combustion engine as claimed in claim 10, wherein the axial slide sleeve (114) includes an axial receiving opening (120) for receiving the swirl grate (117) in a choking position. 12. The internal combustion engine as claimed in claim 10, wherein the axial slide sleeve (114) is biased into its open position by a spring element (119). 13. The internal combustion engine as claimed in claim 10, wherein the axial slide sleeve (114) forms a stop for the blocking element (109), the blocking element (109) coming into contact with the axial slide sleeve (114) to close the inlet opening (107) to the compressor intake duct (105). 14. The internal combustion engine as claimed in claim 6, wherein the blocking element (109) comprises an axially displaceable blocking plunger in the compressor intake duct, the cross-section of an inlet opening (107) of the compressor intake duct (105) being variably adjustable between an open and a closed position by the blocking plunger (104).