Heating device for an exhaust system
First Claim
1. An exhaust system for an internal combustion engine, the exhaust system comprising:
- an exhaust line comprising an exhaust pipe with a pipe wall having an inner side defining an exhaust gas path for guiding an exhaust gas flow;
a reactant feed device connected to the exhaust pipe, said reactant feed device comprising an injector for introducing reactant into the exhaust gas flow and a mixer arranged in the exhaust pipe downstream of the injector;
an electric heating device for heating a length section of the exhaust pipe, the heating device comprising;
a heating coil, which winds several times around the exhaust pipe on an outer side of the pipe wall, in the length section, the heating coil comprising an electric conductor formed of a resistance heating material;
a heat-insulating cover, which envelops the exhaust pipe at least in the areas of the heating coil; and
an electric insulator arranged between the conductor and the outer side of the pipe wall, the heating device being arranged in an area of the mixer and in an area of the reactant feed device, the mixer comprising a cylindrical pipe body and a plurality of guide blades projecting from the cylindrical pipe body, which is in contact with the inner side of the pipe wall, wherein in an area of the mixer, the pipe wall has an axial interruption, which is bridged by the pipe body, wherein at least one of the heating coil is directly in contact with the pipe body in the area of the interruption and the heating coil has a higher winding density in an area of the pipe body than outside the area of the pipe body.
2 Assignments
0 Petitions
Accused Products
Abstract
An exhaust system (1) for an internal combustion engine has an exhaust line (2), which has at least one exhaust pipe (3) having a pipe wall (4) with an inner side (5) defining an exhaust gas path (6) guiding an exhaust gas flow (7) and an electric heating device (18) for heating at least one length section of the exhaust pipe (3). An efficient design is obtained if a heating coil (21) is wound several times around the exhaust pipe (3) on an outer side (22) of the pipe wall (4) in the respective length section and has an electric conductor (23) made of a resistance heating material. An electric insulator (24) is arranged between the conductor (23) and the outer side (22) of the pipe wall (4). A heat-insulating cover (25) envelops the exhaust pipe (3) at least in the area of the respective heating coil (21).
12 Citations
19 Claims
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1. An exhaust system for an internal combustion engine, the exhaust system comprising:
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an exhaust line comprising an exhaust pipe with a pipe wall having an inner side defining an exhaust gas path for guiding an exhaust gas flow; a reactant feed device connected to the exhaust pipe, said reactant feed device comprising an injector for introducing reactant into the exhaust gas flow and a mixer arranged in the exhaust pipe downstream of the injector; an electric heating device for heating a length section of the exhaust pipe, the heating device comprising; a heating coil, which winds several times around the exhaust pipe on an outer side of the pipe wall, in the length section, the heating coil comprising an electric conductor formed of a resistance heating material; a heat-insulating cover, which envelops the exhaust pipe at least in the areas of the heating coil; and an electric insulator arranged between the conductor and the outer side of the pipe wall, the heating device being arranged in an area of the mixer and in an area of the reactant feed device, the mixer comprising a cylindrical pipe body and a plurality of guide blades projecting from the cylindrical pipe body, which is in contact with the inner side of the pipe wall, wherein in an area of the mixer, the pipe wall has an axial interruption, which is bridged by the pipe body, wherein at least one of the heating coil is directly in contact with the pipe body in the area of the interruption and the heating coil has a higher winding density in an area of the pipe body than outside the area of the pipe body. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. An exhaust system in accordance with 9, wherein the pipe body is arranged in an interior of the pipe wall.
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11. An exhaust system in accordance with 10, wherein the pipe wall has an inner pipe wall surface, the pipe body comprising a first pipe body portion and a second pipe body portion, the first pipe portion engaging a first portion of the inner pipe wall surface and the second pipe body portion engaging a second portion of the inner pipe wall surface.
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12. An exhaust system in accordance with 11, wherein the pipe body comprises a third pipe body portion, the third pipe body portion extending between the first portion of the inner pipe wall surface and the second portion of the inner pipe wall surface, wherein the third pipe body portion does not contact the pipe wall.
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13. An exhaust system in accordance with 12, wherein the third pipe body portion is in direct contact with one or more of the electrically insulating filling and the electric insulator.
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14. An exhaust system for an internal combustion engine, the exhaust system comprising:
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an exhaust line comprising an exhaust pipe with a pipe wall having an inner side defining an exhaust gas path for guiding an exhaust gas flow, the pipe wall having a first pipe wall portion and a second pipe wall portion, the first pipe wall portion being located at a spaced location from the second pipe wall portion to define a gap between the first pipe wall portion and the second pipe wall portion, the first pipe wall portion comprising a first pipe wall portion inner surface, the second pipe wall portion comprising a second pipe wall portion inner surface; a reactant feed device connected to the exhaust pipe, the reactant feed device comprising an injector for introducing reactant into the exhaust gas flow and a mixer arranged in the exhaust pipe downstream of the injector; and an electric heating device for heating a length section of the exhaust pipe, the heating device comprising; a heating coil, which winds several times around the exhaust pipe on an outer side of the pipe wall, in the length section, the heating coil comprising an electric conductor formed of a resistance heating material; a heat-insulating cover, which envelops the exhaust pipe at least in the areas of the heating coil; an electric insulator arranged between the conductor and the outer side of the pipe wall, said heating device being arranged in an area of the mixer and in an area of the reactant feed device, the mixer comprising a cylindrical pipe body and a plurality of guide blades projecting from the cylindrical pipe body, the gap being located in an area of the mixer, the pipe body bridging the gap, said pipe body being in direct contact with the first pipe wall portion inner surface and the second pipe wall portion inner surface, wherein at least one of the heating coil is directly in contact with the pipe body in the area of the gap and the heating coil has a higher winding density in an area of the pipe body than outside the area of the pipe body.
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15. A method for operating an exhaust system for an internal combustion engine, the method comprising the steps of:
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providing the exhaust system with an exhaust line comprising an exhaust pipe having a pipe wall with an inner side defining an exhaust gas path for guiding an exhaust gas flow, the exhaust system further comprising an electric heating device for heating a length section of the exhaust pipe, which heating device comprises a heating coil wound several times around the exhaust pipe on an outer side of the pipe wall in the length section, the exhaust system further comprising a reactant feed device connected to the exhaust pipe, the reactant feed device comprising an injector for introducing reactant into the exhaust gas flow and a mixer arranged in the exhaust pipe downstream of the injector, the heating device being arranged in an area of the mixer and in an area of the reactant feed device, the mixer comprising a cylindrical pipe body and a plurality of guide blades projecting from the cylindrical pipe body, which is in contact with the inner side of the pipe wall, wherein in an area of the mixer, said pipe wall has an axial interruption, which is bridged by the pipe body, wherein at least one of the heating coil is directly in contact with the pipe body in the area of the interruption and the heating coil has a higher winding density in an area of the pipe body than outside the area of the pipe body; and controlling and/or regulating the energization of the heating coil such that at least one area in the exhaust pipe, which area is exposed to the risk of condensation of an evaporated liquid being entrained in the exhaust gas flow or to the risk of precipitation of a liquid introduced into the exhaust gas flow, is heated to above an evaporation temperature of the respective liquid. - View Dependent Claims (16, 17, 18, 19)
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Specification