Exhaust heating element

Abstract

The invention relates to an exhaust gas heating element, an exhaust gas heating unit for an exhaust gas device of an internal combustion engine, comprising: a housing heat conductor element (12), comprising a housing (16) and an electric heat conductor (14) extending in the housing (16) and surrounded by an insulating material (18); and a heat transfer surface forming part (20) arranged on the outer side (16) of the housing and in heat transfer contact with the housing.

Description

[0001] This divisional application is a divisional application based on the Chinese invention patent application No. 202010068159.2, invention name “Exhaust Heating Element”, and application date January 21, 2020. Technical Field

[0002] The invention relates to an exhaust gas heating element for an exhaust gas system of an internal combustion engine. Background Art

[0003] The ever-tightening requirements regarding the emission of harmful substances from internal combustion engines require special measures, which are used to reduce the emission of harmful substances in cold components of the exhaust system, even during the start-up phase of the internal combustion engine. In such a start-up phase, in particular, the catalyst units provided in the exhaust system, such as three-way catalysts, oxidation catalysts or SCR catalysts, are at a temperature that is usually insufficient to trigger the catalytic reaction to be carried out therein. In order to cope with this problem, in order to increase the exhaust gas temperature and thus to achieve faster heating of such catalysts or also particle filters, for example, fuel injection can be carried out at a later time in diesel internal combustion engines or the ignition angle can be adjusted to a later time in Otto internal combustion engines, which, however, requires significant intervention in engine management. Summary of the invention

[0004] The object of the present invention is to provide an exhaust gas heating unit for an exhaust gas system of an internal combustion engine which allows efficient heating of system regions of the exhaust gas system, in particular during the starting phase of the internal combustion engine.

[0005] According to the invention, this object is achieved by an exhaust gas heating unit for an exhaust gas system of an internal combustion engine, the exhaust gas heating unit having:

[0006] - a housing heat conductor element comprising a housing and an electrical heat conductor extending in the housing and surrounded by an insulating material,

[0007] A heat transfer surface formation which is arranged on the outer side of the outer casing and is in heat transfer contact with the outer casing.

[0008] The use of such a high-temperature-resistant housing heat conductor element enables very high temperatures in the range of 600° C. to 800° C. to be provided on the housing of the housing heat conductor element and thereby also in the region of the heat transfer surface formation which is in heat transfer contact with the housing. The thermal energy provided can be utilized to heat system regions of the exhaust gas system, for example by transporting the thermal energy from the exhaust gas of a circulating exhaust gas heating unit to such system regions.

[0009] In order to achieve good heat transfer between the outer cover and the heat transfer surface shaped part while still maintaining a stable structure, it is proposed that the outer cover is constructed of a metal material, or / and the heat transfer surface shaped part is frictionally locked with the outer cover, preferably by press-fitting or shrink-fitting, or / and the material connection is preferably connected by welding or soldering.

[0010] The heat transfer surface shaping can have a heat transfer element which provides at least one heat transfer surface which surrounds the housing heat conductor element in a spiral winding manner, preferably substantially orthogonal to the outer peripheral wall of the housing. Due to this spiral winding configuration, a large surface is provided for thermal interaction with the exhaust gas of the circulating exhaust gas unit with a small number of components and thus a simple to implement design.

[0011] For good thermal interaction of the exhaust gas heating unit, it is proposed that the housing heat conductor element is at least partially designed to extend in a straight line or / and at least partially designed to extend in a helical manner or / and at least partially designed to extend in a meandering manner.

[0012] In an alternative configuration, the heat transfer surface shaped portion can have a plurality of plate-shaped heat transfer elements which are arranged at a distance from one another.

[0013] In order to keep the flow resistance low while nevertheless ensuring good heat transfer capabilities, it is proposed that the heat transfer elements are arranged essentially parallel to one another or / and that spacing elements contacting or / and connected to the heat transfer elements are arranged between at least two heat transfer elements, preferably between all heat transfer elements directly adjacent to one another.

[0014] At least one, preferably each, spacing element can substantially completely cover the heat transfer elements arranged on both sides thereof in the mutually opposite surface areas of the heat transfer elements. For a stable connection that nevertheless ensures good heat transfer, it is proposed that at least one, preferably each, spacing element is formed with a wavy structure and rests with the wave peak area on the heat transfer elements arranged on both sides thereof or / and is connected to the heat transfer elements. If at least one, preferably each, spacing element is permeable for exhaust gas, a good circulation of exhaust gas is ensured over all surface areas. For example, it can be provided that such spacing elements are formed as a wire mesh, as a perforated plate material or as a metal plate mesh (streckmetall).

[0015] In order to connect the sheathing heat conductor element to the plate-shaped heat transfer element, it is proposed that at least one, preferably a plurality of, sheathing heat conductor element receiving recesses for receiving at least one sheathing heat conductor element are provided in at least one, preferably each, heat transfer element.

[0016] In order to ensure efficient heat transfer from the outer cover heat conductor element to the plate-shaped heat transfer element, it can be further provided that in at least one, preferably each heat transfer element, at least one, preferably each outer cover heat conductor element receiving gap is open to the circumferential edge area of ​​the heat transfer element, or / and in at least one, preferably each heat transfer element, at least one, preferably multiple outer cover heat conductor element receiving gaps are respectively provided on the circumferential edge areas of the heat transfer elements opposite to each other or extending at an angle relative to each other, or / and at least one heat transfer element pair, preferably multiple heat transfer element pairs are provided, wherein the outer cover heat conductor element is positioned so as to be embedded in at least one outer cover heat conductor element receiving gap of each heat transfer element of the at least one heat transfer element pair.

[0017] In a particularly advantageous further development of the exhaust gas heating unit according to the invention, the heat transfer surfaces of the heat transfer surface formation can be provided at least in regions with a catalytic material. The exhaust gas heating unit is thus used not only for heating but also for directly using the heat provided therein to carry out a catalytic reaction.

[0018] For example, at least one, preferably each, heat transfer element of the heat transfer surface formation can be coated with a catalytically active material.

[0019] For a stable connection of such a coating to the heat transfer element, it is advantageous if the at least one heat transfer element is formed from an aluminum material, preferably an aluminum alloy, for example the FeCr alloy 1.4767.

[0020] In particular, if the exhaust gas heating unit is to function as a three-way catalytic converter or as a diesel oxidation catalytic converter, the catalytically active material may have:

[0021] - Platinum, or / and

[0022] - Palladium, or / and

[0023] -rhodium.

[0024] If the exhaust gas heating unit is to function as an SCR catalytic converter, the catalytically active material can have:

[0025] - iron-zeolite-materials, or / and

[0026] - copper-zeolite-materials, or / and

[0027] - Vanadium-oxide-materials.

[0028] The invention further relates to an exhaust gas system for an internal combustion engine having at least one exhaust gas heating element arranged in an exhaust gas flow duct and designed according to the invention.

[0029] In order to be able to efficiently utilize the heat provided in the exhaust gas heating unit and transferred to the exhaust gas in the exhaust gas system, the exhaust gas heating element is preferably arranged upstream of an exhaust gas treatment unit, in particular a catalytic converter unit or a particle filter unit, in the exhaust gas flow direction in the exhaust gas flow channel.

[0030] In particular, if the exhaust gas heating unit itself is catalytically designed, it is advantageous if the catalytic material and the catalyst unit are assigned to the same catalyst type. This means that if, for example, the exhaust gas heating unit is to function as a three-way catalytic converter and is coated or designed with a corresponding catalytic material for this purpose, the catalyst unit arranged downstream thereof is also of the type of a three-way catalytic converter. Thus, for example, an exhaust gas heating unit which is heated very quickly by the housing heat conductor element during the start-up phase can function as a catalytic converter even if the three-way catalytic converter following downstream is not yet catalytically active due to the low temperatures.

[0031] For even faster heating of the exhaust system, it is proposed that a hydrocarbon discharge arrangement for discharging hydrocarbons into the exhaust gas flow is assigned to at least one exhaust gas heating unit upstream of the exhaust gas heating unit. Hydrocarbons, i.e., gasoline or diesel, which react on the hot surfaces of the exhaust gas heating unit, release considerable heat in their reaction, which heats the exhaust gas flowing there in the environment of the exhaust gas heating unit and thus assists in the effective heating of system regions further downstream. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Next, the present invention will be described in detail with reference to the accompanying drawings.

[0033] Figure 1 A perspective view showing a portion of an exhaust gas heating unit including a high temperature resistant hood heater;

[0034] Figure 2 Show Figure 1 A side view of an exhaust unit;

[0035] Figure 3 A diagram showing a schematic diagram of an exhaust gas device including an exhaust gas heating unit;

[0036] Figure 4 A view showing an exhaust gas heating unit in an exhaust gas channel as seen in the exhaust gas flow direction;

[0037] Figure 5 Another alternative arrangement of the exhaust gas heating unit is shown corresponding to Figure 4 's view;

[0038] Figure 6 A perspective view showing another alternative arrangement of an exhaust gas heating unit;

[0039] Figure 7 Another alternative arrangement of the exhaust gas heating unit is shown corresponding to Figure 4 's view;

[0040] Figure 8 An alternative design of an exhaust gas heating unit is shown;

[0041] Fig. 9 Show Figure 8 a portion of a plurality of plate-shaped heat transfer elements of an exhaust heating unit;

[0042] Fig.10 The heat transfer elements are shown in pairs. Fig. 9 's picture;

[0043] Fig.11 An alternatively designed heat transfer element is shown;

[0044] Fig.12 A layering of plate-like heat transfer elements comprising spacer elements arranged therebetween with a corrugated structure is shown;

[0045] Fig.13 Shown is a thermal conductor element in combination with an outer cover Fig.12 Heat transfer elements;

[0046] Fig.14 A portion of a heat transfer element coated with a catalytically active material is shown;

[0047] Fig.15 An exhaust gas system is shown which comprises an exhaust gas heating unit which is arranged upstream of a catalytic converter unit;

[0048] Fig.16 An exhaust system is shown which comprises an exhaust heating unit which is arranged in an exhaust pipe upstream of a catalytic converter unit;

[0049] Fig.17 An exhaust gas heating unit is shown including a hydrocarbon exhaust arrangement assigned thereto. DETAILED DESCRIPTION

[0050] Figure 1 and 2 An exhaust gas heating unit 10 for an exhaust gas system of an internal combustion engine is shown. The exhaust gas heating unit 10 has a housing heat conductor element 12, which is particularly resistant to high temperatures and includes a heat conductor 14 arranged in its core region. The heat conductor 14 can have one or more heating wires and is surrounded by an insulating material 18, for example a ceramic material, in an interior space surrounded by a housing 16.

[0051] A heat transfer surface shaped portion 20 is arranged on the outer surface 28 of the housing 16 constructed of a metal material, for example a steel material. In the illustrated design example, the heat transfer surface shaped portion 20 has a heat transfer element 22 which surrounds the housing heat conductor element 12 in a spiral winding manner and is connected to its outer surface 28. On two sides oriented substantially in the longitudinal extension direction of the housing heat conductor element 12, the heat transfer element 22 constructed in a spiral winding manner provides heat transfer surfaces 24, 26, which can be circulated by the exhaust gas and on which the heat received by the housing 16 can be transferred to the exhaust gas. Of course, heat transfer to the exhaust gas circulating around it also occurs in the region of the outer surface 28 of the housing 16.

[0052] The helically wound heat transfer element 22 is preferably connected to the outer surface 28 of the housing 16 in a material-locking manner, for example by welding or soldering. This can also be provided in addition or alternatively by press-fitting or shrink-fitting the heat transfer element 22 onto the housing 16.

[0053] By means of the spirally wound structure of the heat transfer element 22, a very large total area for the heat transfer surface is provided by a single component. It should be noted that a similar arrangement can also be achieved if a plurality of heat transfer elements of washer-like design are arranged at, for example, substantially uniform distances from one another on the outer circumference 28 of the housing 16. In this case, however, a plurality of individual heat transfer elements are provided, each of which must be fastened to the outer surface 28 of the housing 16.

[0054] Figure 3 The schematic diagram shows the design of an exhaust system 30 for an internal combustion engine 32. The exhaust system 30 has an exhaust duct 36 in a one-piece or multi-piece exhaust pipe 34. In the exhaust duct 36, an exhaust gas treatment unit 10 is arranged upstream of an exhaust gas treatment unit 38, for example a catalytic converter unit 40, which can have, for example, the exhaust gas treatment unit 10 described above. Figure 1 and 2 In the illustrated design example, the exhaust gas treatment unit 10 or its housing heat conductor element 12 is arranged upstream of the exhaust gas treatment unit in a substantially elongated or straight manner extending in the exhaust gas flow direction in the exhaust gas duct 36. At both longitudinal ends of the exhaust gas treatment unit 10, the exhaust gas treatment unit is in contact with electrical conductors 42, 44, via which the exhaust gas treatment unit 10 is connected to a power supply 46.

[0055] In particular, during the start-up phase of the internal combustion engine 32, in which the exhaust gas system 10, in particular also the catalytic converter unit 40, is cold and thus a catalytic reaction cannot be initiated therein, the exhaust gas treatment unit 10 can be excited by applying a voltage, so that the outer heat conductor element 12 and also the heat transfer surface shaped part 20 are heated. The exhaust gas coming into contact with the heat transfer surfaces 24, 26 or the outer surface 28 receives heat and transports it to the catalytic converter unit 40, so that at still relatively low exhaust gas temperatures or with the aid of heat energy already conveyed in the exhaust gas, a relatively rapid heating of the catalytic converter unit 40 is ensured and thus a relatively rapid reaching of a temperature at which a catalytic reaction can be initiated.

[0056] Figures 4 to 7 Different spatial arrangements of such an exhaust gas treatment unit 10 are shown in the exhaust gas duct 36. Thus, for example Figure 4 The configuration of the housing heat conductor element 12, which is wound essentially in a plane orthogonal to the exhaust gas flow direction A, in particular in the manner of a double helix, is shown, and includes a heat transfer surface shaped portion 20 arranged on the outer circumference 28 of the housing heat conductor element. The two ends 48, 50 of the housing heat conductor element 12, which are exposed outside the exhaust pipe for electrical contacting, are located in the same length region of the exhaust pipe 34 and can therefore be electrically connected to the power source 46 in a simple manner.

[0057] Figure 5 An arrangement is shown in which the housing heat conductor element 12 is again wound in a single helix in a plane that is substantially orthogonal to the exhaust gas flow direction A. The heat conductor 14 provided in the housing heat conductor element 12 has two heating wires in this embodiment, which extend side by side and merge into one another at an end 50 of the housing heat conductor element 12 that is located in the central region, so that the two heating wires can be contacted at the end 48 of the housing heat conductor element 12 that is located outside the exhaust gas pipe 34.

[0058] Figure 6 An arrangement is shown in which the housing heat conductor elements 12 are arranged in two helical winding arrangements one behind the other. Thus, the two ends 48, 50 to be electrically contacted can be guided through the exhaust pipe 34 at a distance, for example in the exhaust gas flow direction A, which also corresponds approximately to the distance between the two helical winding areas, each of which is essentially in one plane.

[0059] Figure 7A configuration is shown in which the exhaust gas heating unit 10 is arranged in an exhaust gas pipe 34 or an exhaust gas-conducting housing having a flat, approximately rectangular cross section. The housing heat conductor element 12 is arranged in a meandering manner and has meander sections 52 extending approximately parallel to each other and each extending substantially straight, which are connected by corresponding bending regions 54 of the housing heat conductor element 12. In this way, the structure of the exhaust gas heating unit 10 can be easily adapted to the circumferential contour of the exhaust gas pipe 34 or the housing that receives it, which also contributes to the fact that the heat transfer surface shaped portion 20 is arranged on the outer surface 28 of the housing heat conductor element 12 in a spirally wound manner or in the form of a plurality of washers and can therefore be easily adapted to the curved or bent configuration of the housing heat conductor element 12.

[0060] Figure 8 An alternative design of the exhaust gas heating unit 10 is shown, in which the outer shell heat conductor element 12 is in contact with a plurality of plate-shaped heat transfer elements 56 of the heat transfer surface forming part 20 which are arranged substantially parallel to each other. Figure 8 As shown in , such a design can also be easily adapted to various circumferential contours of the exhaust pipe 34 or the housing that receives the exhaust gas heating unit 10 .

[0061] For efficient heat transfer between the outer cover heat conductor element 12 and the heat transfer element 56, the outer cover heat conductor element 12 is designed to be wound in a meandering manner and has the characteristics already mentioned in reference. Figure 7 The meandering section 52 and the curved area 54 connecting the meandering section. In particular, the meandering section 52 is configured, as in Fig. 9 As shown in FIG. 1 , housing heat conductor element receiving gaps 58 are formed in the plate-shaped heat transfer element 56. These housing heat conductor element receiving gaps are open toward the heat transfer element peripheral edge region 60 and have a semicircular configuration adapted to the, for example, circular outer peripheral contour of the housing 16. The housing heat conductor element 12 can be fitted into these housing heat conductor element receiving gaps 58, for example, under a press fit, or / and can be connected to the respective heat transfer element 56 by material locking, for example, by soldering or welding.

[0062] In order to increase the stability of the exhaust gas heating unit 10 constructed in this way, the plate-shaped heat transfer elements 56 can be connected to each other and also to the exhaust gas pipe 34 or housing accommodating them via brackets (not shown in the figures).

[0063] Fig.10An arrangement is shown in which two such plate-shaped heating elements 56 are arranged opposite one another and thus provide a heat transfer element pair 62. Here, the housing heat conductor element receiving recesses 58 formed in the heat transfer elements 56 of the heat transfer element pair 62 are arranged opposite one another, so that the two heat transfer elements 56 of the respective heat transfer element pair 62 together substantially completely surround the housing 16 of the housing heat conductor element 12 approximately in the same length region.

[0064] The heat transfer elements 56 are arranged in pairs to increase the overall surface area available for heat transfer. Since the heat transfer elements 56 of the corresponding heat transfer element pairs 62 are substantially not offset from each other in the longitudinal extension direction of the outer cover heat conductor element 12, the flow resistance of the exhaust gas flowing around the exhaust gas heating element 10 configured in this way is kept low. It should be noted that, in particular, when strong eddies are to be generated in the exhaust gas flow, the heat transfer elements 56 of the corresponding heat transfer element pairs 62 can also be offset from each other in the longitudinal extension direction of the heat conductor element 12 guided past the heat transfer elements.

[0065] Fig.11 A heat transfer element 56 is shown, wherein corresponding housing heat conductor element receiving recesses 58 are formed in mutually opposite heat transfer element circumferential edge regions 60, 64. It is thus possible to arrange at least one housing heat conductor element 12 on both sides of the heat transfer element 56, for example on the upstream and downstream sides, and to connect them rigidly.

[0066] Fig.12 An arrangement is shown in which a spacer element 66 of wavy structure is arranged between heat transfer elements 56 arranged substantially parallel to one another. This results in a stable overall structure, wherein the spacer element 66 can be connected to the heat transfer element 56 arranged adjacent thereto in the wave crest region 68, for example by welding or brazing or adhesive bonding. These spacer elements 66, which are preferably also made of metallic material, increase the overall surface available for heat transfer and substantially completely cover the heat transfer elements 56 arranged on both sides thereof. Where the housing heat conductor element receiving recess 58 is provided in the heat transfer element, the respective spacer element 66 can be set back from the corresponding circumferential edge region of the adjacent heat transfer element 56 in order to provide a simple to implement structure.

[0067] In order to avoid the generation of flow blind spots or areas that are difficult to flow into, the spacer element 66 can be configured so that it can be flowed through by exhaust gas. For example, the spacer element can be provided by a wire mesh or a perforated plate or a metal plate mesh and thus has many openings that enable the passage of exhaust gas.

[0068] Such a connection of heat transfer surface element 56 can also be supported on the exhaust pipe or on a housing supporting the exhaust pipe by means of retaining elements (not shown), so that vibrations occurring during driving operation do not lead to position changes of the exhaust gas heating unit constructed in this way in the exhaust pipe or the housing.

[0069] Fig.14 A section of a heat transfer element 70, for example, of plate-like design, is shown, which is coated at least partially with a catalytic material 72 on its outer surface, over which exhaust gas can flow. For a stable connection of such a catalytic material, it is advantageous to provide such a heat transfer element 70 from aluminum or an aluminum alloy with a high aluminum content. Usually, when applying such a catalytic material 72, the metal surface is first covered with a porous oxide ceramic coating, known as a washcoat, with a large inner surface. The catalytic material is then applied to this coating, for example in a so-called dipping process.

[0070] By applying the catalytic material 72 to one or more heat transfer elements 70, it is possible to very quickly bring the heat transfer element 70 or the catalytic coating 72 to a temperature at which a catalytic reaction can take place when exhaust gas flows around it, even during the start phase of the internal combustion engine. This makes it possible to provide a catalytic effect in the exhaust system almost without any time delay and thus also to significantly reduce the pollutant emissions immediately after the start of the internal combustion engine.

[0071] Such a coating comprising a catalytically active material can be provided independently of the design of the heat transfer surface shaped part. Figure 1-13 In the configuration shown in FIG. 1 , one or more of the heat transfer elements are covered on at least one side, but preferably completely, with a catalytically active material.

[0072] The catalytic material 72 is selected depending on what type of catalytic effect is to be provided in this way. If, for example, the exhaust gas heating unit 10 is to function as a three-way catalytic converter, the catalytic material can contain platinum, palladium, rhodium or a mixture thereof. Structural promoters that improve the heat resistance of the catalytic material 72 can also be arranged in the coating. If the effect of a diesel oxidation catalyst is to be achieved, it is advantageous to use platinum and palladium as the main components of the catalytic material 72. Mixed oxides can also be used. If the effect of an SCR catalyst is to be achieved, it is advantageous to provide the catalytic material with an iron-zeolite material, a copper-zeolite material or a vanadium-oxide material, for example a vanadium-pentoxide.

[0073] The catalytic converter effect can then be utilized in a particularly effective manner if Fig.15As described, such an exhaust gas heating unit 10 provided with a catalytically active material is arranged, for example, in a catalyst housing 74 upstream of the catalyst unit 40 arranged therein. It should be noted that in a typical design, the catalyst unit 40 can have, for example, a monolith 76 formed or covered with a catalytically active material, which can be held in the catalyst housing 74 by a fiber mat 78 surrounding it.

[0074] In such a configuration, it is preferably provided that the catalytically active material 72 provided on the exhaust gas heating unit 10 and the catalyst unit 40 provide the same type of catalytic reaction. Figure 3 After the start of the internal combustion engine 32 described in the figure, the exhaust gas heating unit 10 together with the catalytically active material 72 arranged thereon is brought to the temperature required for carrying out the catalytic reaction very quickly by electrical excitation and thus functions as a catalyst, even before the catalyst unit 40 reaches the temperature required for this. The catalyst unit 40 is heated on the one hand by the exhaust gas also ejected by the internal combustion engine 32 during the start phase and on the other hand by the exhaust gas circulating around the exhaust gas heating unit 10 and thus is also brought to a sufficiently high temperature very quickly in order to also carry out the catalytic reaction therein. If this temperature is reached, the excitation of the outer housing heat conductor element 12 of the exhaust gas unit 10 can be terminated. This can be detected by providing a temperature signal, or a defined time interval can be provided, at which the exhaust gas heating unit 10 is excited during the start phase of the internal combustion engine 32.

[0075] Fig.16 A design is shown in which the exhaust gas heating unit 10 is not arranged in the catalyst housing 74 upstream of the catalyst unit 40, but in the exhaust pipe 34 connected to the end upstream of the catalyst housing. Such an arrangement can be advantageous, for example, in the case where the exhaust gas heating unit 10 is to have a Figure 1 and 2 The elongated configuration shown in FIG.

[0076] Fig.17An exhaust system 30 is shown, in which a hydrocarbon discharge arrangement 80 is arranged in an exhaust heating unit 10, which is also provided with a catalytically active material 72, for example. The hydrocarbon discharge arrangement can inject hydrocarbons, that is, for example, fuel used for operating the internal combustion engine 32, into the exhaust gas flow in the direction of the exhaust unit 10 in the manner of an injector. The hydrocarbons react on the hot surfaces of the exhaust heating unit 10, so that the conversion of the hydrocarbons releases reaction heat, which can be additionally transferred to the exhaust gas flowing in the direction of the catalytic converter unit 40 that follows downstream. Such a design is particularly advantageous if the catalytic converter unit 40 is designed as an SCR catalytic converter, on which a selective catalytic reduction is carried out by converting a reducing agent, that is, for example, a urea / water solution, injected by a reducing agent discharge arrangement (not shown). The particle filter used as the exhaust gas treatment unit 38 can also be regenerated independently of the operation of the internal combustion engine 12 by injecting hydrocarbons.

[0077] In another embodiment, hydrocarbons transported in the exhaust gas flow can also be provided in that the exhaust gas flow is ejected in a targeted manner from the internal combustion engine 32. For this purpose, it can be ensured, for example, by correspondingly adjusting the ignition angle or by late fuel injection, that only a portion of the fuel is ignited in the combustion taking place in the internal combustion engine 32, while a portion of the fuel is ejected unburned and provided for conversion at the exhaust gas heating unit 10 and / or the exhaust gas treatment unit 38.

Claims

1. An exhaust gas system for an internal combustion engine, comprising at least one exhaust gas heating unit (10) arranged in an exhaust gas flow channel (36) through which exhaust gas can flow in an exhaust gas flow direction (A), wherein: The exhaust gas heating unit (10) comprises: a housing heat conductor element (12), comprising a housing (16) and an electrical heat conductor (14) extending in the housing (16) and surrounded by an insulating material (18), the housing heat conductor element (12) being designed in the manner of a double helix and extending at least partially in a helical manner in a plane orthogonal to the exhaust gas flow direction (A), A heat transfer surface formation (20) arranged on the outer side of the housing (16) and in heat transfer contact with the housing, wherein the heat transfer surface formation (20) has at least one heat transfer element (22) which surrounds the housing heat conductor element (12) in a helical winding manner.

2. The exhaust device according to claim 1, characterized in that The outer cover (16) is constructed of a metal material, and / or the heat transfer surface shaping portion (20) is connected to the outer cover (16) by friction locking or / and material locking.

3. The exhaust device according to claim 2, characterized in that The heat transfer surface forming portion (20) is connected to the outer cover (16) by press-fitting and / or by welding or brazing.

4. The exhaust device according to claim 1 or 2, characterized in that: The heat transfer element (22) provides a heat transfer surface (24, 26) perpendicular to the peripheral wall of the housing.

5. The exhaust device according to claim 4, characterized in that The sheath heat conductor element (12) is at least partially designed to extend in a straight line or / and the sheath heat conductor element (12) is at least partially designed to be spirally wound or / and the sheath heat conductor element (12) is at least partially designed to extend in a meandering manner.

6. The exhaust device according to claim 1 or 2, characterized in that: The heat transfer surface of the heat transfer surface shaped part (20) is provided at least partially with a catalytically active material (72).

7. The exhaust device according to claim 6, characterized in that At least one heat transfer element (70) of the heat transfer surface formation is coated with a catalytically active material (72).

8. The exhaust device according to claim 7, characterized in that Each heat transfer element (70) of the heat transfer surface formation is coated with a catalytic material (72).

9. The exhaust device according to claim 7, characterized in that The at least one heat transfer element (70) is formed from an aluminum material.

10. The exhaust device according to claim 9, characterized in that The at least one heat transfer element (70) is formed from an aluminum alloy.

11. The exhaust device according to claim 6, characterized in that The catalytic material (72) has: - Platinum, or / and - palladium, or / and -rhodium.

12. The exhaust device according to claim 6, characterized in that The catalytic material (72) has: - iron-zeolite-materials, or / and - copper-zeolite-materials, or / and - Vanadium-oxide-materials.

13. The exhaust device according to claim 1 or 2, characterized in that: The exhaust gas heating unit (10) is arranged upstream of the exhaust gas treatment unit (38) in the exhaust gas flow channel (36) along the exhaust gas flow direction (A).

14. The exhaust device according to claim 13, characterized in that The exhaust gas heating unit (10) is arranged upstream of the catalytic converter unit (40) or the particle filter unit in the exhaust gas flow channel (36) in the exhaust gas flow direction (A).

15. The exhaust device according to claim 14, characterized in that The heat transfer surface of the heat transfer surface shaped part (20) is provided at least in regions with a catalytically active material (72), and the catalytically active material (72) and the catalyst unit (40) are assigned to the same catalyst type.

16. The exhaust device according to claim 1 or 2, characterized in that: A hydrocarbon discharge arrangement (80) for discharging hydrocarbons into an exhaust gas flow is assigned to at least one exhaust gas heating unit (10) upstream of the exhaust gas heating unit (10).

17. The exhaust device according to claim 2, characterized in that The heat transfer surface forming portion (20) is connected to the outer cover (16) by heat press fitting.

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