Device for the aftertreatment of exhaust gases

Abstract

Device (1) for the aftertreatment of exhaust gases of an internal combustion engine with at least one electrical heating conductor (3) which is arranged in a plane (10) inside a flow path (9) bounded by a housing (2), wherein the at least one heating conductor (3) can be electrically contacted by means of at least one electrical feedthrough (11) through the housing (2), and the at least one heating conductor (3) is electrically connected to the at least one electrical feedthrough (11) inside the housing (2) by means of at least one conductor rail (5), characterized in that the at least one conductor rail (5) contacts the at least one electrical feedthrough (11) outside the plane (10) and the at least one heating conductor (3) in the plane (10) and radially offset.

Description

Technical field

[0001] The invention relates to a device for the aftertreatment of exhaust gases from an internal combustion engine with an electric heating conductor which is arranged inside a flow path bounded by a housing, wherein the heating conductor can be electrically contacted by means of an electrical feedthrough which is led through the housing, wherein the electrical feedthrough has an inner conductor which is led from inside the device through its outer housing wall, with an electrical insulating layer, and with a metallic sleeve in which the inner conductor and the electrical insulating layer surrounding the inner conductor are received. State of the art

[0002] Electrically heated catalysts are known in the prior art. These typically have at least one current-carrying conductor connected to a voltage source via an electrical contact. Since the catalysts are gas-tight, special electrical feedthroughs are used. These feedthroughs pass through the outer shell of the catalyst, which can form its housing, and establish an electrically conductive connection between the voltage source and the heating conductor inside.

[0003] The electrical bushing typically includes an electrical conductor embedded in a non-conductive material, such as a ceramic sleeve. This non-conductive material can, in turn, be surrounded by a metal sleeve, which can be permanently and mechanically resistantly bonded to the metallic casing of the catalyst using a joining technique. The electrical bushing, as known in the prior art, thus typically comprises a central conductor, such as a bolt, a ceramic insulating sleeve, and a metallic outer sleeve.

[0004] A disadvantage of the current feedthroughs known in the prior art is that the direct connection of the heating conductor to the central conductor imposes restrictions on possible designs, as the available installation space is regularly very limited. This applies particularly to heating devices located very close to the engine, especially in the engine compartment of a motor vehicle. This is a particular problem with regard to the electrical feedthrough, which is usually positioned as a surface normal on the housing, because the heating conductor may be at an unfavorable angle to the electrical feedthrough, thus preventing direct contact between the heating conductor and the central conductor. It is possible that the electrical feedthrough protrudes into the housing from a side facing away from a direct connection to the heating conductor.It is also possible that the electrical feedthrough protrudes into the housing in an unfavorable direction and / or offset. Description of the invention, problem, solution, advantages

[0005] Therefore, the object of the present invention is to provide a device that allows for an improved and, in particular, more flexible design with regard to the structural arrangement of the heating conductor and the electrical connection. The device should be particularly suitable for overcoming the aforementioned problems, especially in the case of an arrangement close to the motor, at least partially.

[0006] The problem with regard to the device is solved by a device having the features of claim 1.

[0007] One embodiment of the invention relates to a device for the aftertreatment of exhaust gases from an internal combustion engine with at least one electrical heating conductor, which is arranged in a plane inside a flow path bounded by a housing, wherein the heating conductor can be electrically contacted by means of an electrical feedthrough through the housing and the at least one heating conductor is electrically connected to the at least one electrical feedthrough inside the housing by means of at least one conductor rail, wherein the at least one conductor rail contacts the at least one electrical feedthrough outside the plane and the at least one heating conductor in the plane and radially offset.

[0008] The at least one electrical heating element can be located, for example, in a section of the exhaust system (close to the engine) that connects to an engine or internal combustion engine. Part of the exhaust system is formed by the housing, which contains a flow path for the exhaust gas. The housing can act as a flow deflector, allowing the exhaust gas to enter the housing laterally, be deflected by approximately 90°, and then exit along an outlet axis. The housing can consist of a cover and a pipe section, with both components potentially being separate or integrated into a semi-shell design. The electrical heating element is arranged in a plane perpendicular to the flow path or axis.The electrical heating conductor has a planar extension, particularly in the form of a disk with an axial length that is significantly smaller than its diameter. The electrical heating conductor preferably spans substantially the entire flow path and is, in particular, fixed to the housing or its pipe around its circumference. The electrical heating conductor is, in particular, designed as a honeycomb structure through which exhaust gas flows.

[0009] The at least one heating conductor positioned inside is electrically connected to at least one electrical feedthrough through the housing, in particular its cover, by means of at least one busbar. The feedthrough includes, in particular, an electrical connection which is guided, sealed, and insulated through the housing. The feedthrough is typically straight, in particular parallel to the axis of the housing. Specifically, the feedthrough is oriented perpendicular to the heating conductor or its plane of arrangement. It is possible that the feedthrough is located closer to the central axis of a pipe section of the housing in the cover than to the wall of the pipe section. Preferably, the feedthrough terminates near the housing / cover (i.e., further away from the central axis), in particular at an (axial) distance (upstream or in the direction of flow) to the heating conductor of at least 15 mm [millimeters], if necessary.with a distance in the range of 30 mm to 70 mm.

[0010] The cover can be a cast housing or a deep-drawn sheet metal part. It is possible that the pipe section is also a cast housing or a deep-drawn sheet metal part. It is possible that the cover and the pipe section are two components that are bonded together. It is also possible that the cover and the pipe section are manufactured from a single component.

[0011] The heating element is usually connected directly to the center conductor of the electrical bushing. No separate component is provided. To increase flexibility and allow for freer positioning of the electrical bushing and heating element within the housing, a busbar is used. This busbar is connected on one side to the center conductor of the electrical bushing and on the other side to the heating element. The first contact point of the busbar with the bushing lies outside the plane of the heating element, specifically at a predetermined distance upstream of it. The second contact point of the busbar with the heating element lies within the plane of the heating element, with a predetermined radial offset from the first contact point.

[0012] The busbar can establish an electrically conductive connection between the inner conductor and the heating conductor. The shape of the busbar can be adapted to the (especially central) positioning of the inner conductor / electrical bushing or the (especially more distant) electrical connection of the heating conductor. It is also possible for the busbar to have a shape or structure adapted to other or additional flow, temperature, and / or voltage parameters. For example, the busbar can be adapted to accommodate or compensate for (relative) movements of the heating conductor and / or the inner conductor (relative to each other or to the housing). The busbar can be adapted to accommodate or conduct different electrical currents.

[0013] The heating conductor can be attached to a planar support structure, and the at least one conductor rail can extend through the support structure. The planar support structure may not be a closed surface. The heating conductor can be held in the support structure with insulation. Preferably, the support structure has insulated support pins to which the heating conductor is attached.

[0014] In particular, the busbar is designed so that it projects out of the plane of the heating conductor. The inner conductor is axially spaced from the heating conductor and, in particular, arranged outside the plane, so that one end of the busbar projects towards the inner conductor and another end of the busbar projects towards the heating conductor.

[0015] The at least one busbar can be or include a bending element to compensate for axial, radial, and / or torsional relative movements of the at least one heating conductor with respect to the at least one electrical bushing. It is possible that the heating conductor and the inner conductor may undergo relative movements during operation. For example, mechanical, thermal, or other influences can exert forces on the inner conductor and / or the heating conductor, leading to such movement. In particular, axial, radial, and / or torsional forces act on the busbar during such relative movements. To absorb these forces without sustaining damage, the busbar can be or include a bending element.

[0016] The conductor rail can incorporate a bending element, for example, in the form of (local, exposed) arc-shaped sections that can accommodate relative movements. These arc-shaped sections can act as spring elements. It is possible for the relative movements of the conductor rail to be reversible. This allows the conductor rail to return to its original position without damage after a force has been applied and the movement has occurred.

[0017] The at least one conductor rail can (at least partially) encircle the at least one heating conductor or a section thereof. The conductor rail may have a fork-shaped or plug-shaped end that can encircle the heating conductor. This fork-shaped or plug-shaped end of the conductor rail can project into the plane of the conductor and encompass the heating conductor. A planar contact between the conductor rail and the heating conductor is particularly preferred in this way. This ensures that the current is transferred to the heating conductor over at least two surfaces, resulting in a more homogeneous current flow to the heating conductor. It also allows for a more robust connection between the conductor and the heating conductors.

[0018] The electrical bushing can include the inner conductor, which is surrounded by an electrical insulation layer and (further outwards) a metallic sleeve. The electrical insulation layer can directly surround the inner conductor. Preferably, the electrical insulation layer extends around the inner conductor into and out of the housing of the device. Preferably, the inner conductor extends beyond the ends of the electrical insulation layer. Thus, the inner conductor can extend further into and out of the housing of the device than the electrical insulation layer. The metallic sleeve can connect the electrical bushing to the housing. The metallic sleeve can be the only direct connection between the electrical bushing and the housing. Preferably, the metallic sleeve is connected to the electrical insulation layer. This allows the housing to be electrically isolated from the inner conductor.

[0019] The inner conductor can be oriented perpendicular to the plane. In particular, the electrical bushing with the inner conductor can be attached to the housing in such a way that an extension of a central axis of the inner conductor would perpendicularly break the plane. Specifically, the housing is designed so that it projects beyond the plane and the inner conductor can be secured within the electrical bushing.

[0020] The busbar can be oriented horizontally to the plane of the connection area with the inner conductor. One end of the inner conductor can be placed on the busbar and connected there (by a material bond). Due to the horizontal orientation of the busbar, it can provide a contact surface for the inner conductor. In particular, the busbar can be designed in the connection area so that it is oriented perpendicular to the inner conductor.

[0021] Each inner conductor can be connected to one busbar. It is possible that each inner conductor is connected to one busbar and thus to one heating conductor.

[0022] It is possible for several inner conductors to be connected to a busbar containing multiple heating conductors. It is also possible for several inner conductors to be connected to a busbar containing a single heating conductor. Furthermore, it is possible for a single inner conductor to be connected to a busbar containing multiple heating conductors or multiple (spaced-apart) sections of the heating conductor.

[0023] It is possible that the busbar has a contact section in which the inner conductor is connected to the busbar. The busbar can be arranged perpendicular to the inner conductor in the contact section.

[0024] Preferably, the busbar in the contact area extends only in a radial direction relative to the inner conductor. The inner conductor may have a central axis. A radial direction may extend from the central axis. Preferably, the busbar in the contact area extends only in the radial direction. The busbar may have bends. The bends may have an angle of up to 230°, so that parts of the busbar overlap. Preferably, however, the busbar does not have such bends in the contact area. Particularly preferably, the busbar in the contact area has only bends with an angle of no more than 45°.

[0025] The connection to the heating conductor and / or the inner conductor can preferably be made by soldering, which is particularly advantageous because all elements can be connected together in one operation.

[0026] The busbar is preferably made of a temperature-resistant material that can withstand the currents and temperature ranges expected during operation without damage.

[0027] It is particularly advantageous if the busbar is spaced from other elements within the housing in such a way that no electrically conductive connection is formed. This is necessary to prevent the formation of an unwanted current path and potentially connecting the housing or other components to the voltage source. Therefore, a sufficiently large insulation gap must be maintained between the busbar and all other elements in the device.

[0028] It is also advantageous if the busbar is designed in such a way that currents of up to 300 amperes can flow through it without damage. The busbar must therefore have a sufficiently large cross-section so that the currents carried through it during operation do not overheat it.

[0029] A preferred embodiment is characterized in that the busbar is made of an electrically conductive material that can withstand temperatures up to approximately 1000 degrees Celsius without damage. Since temperatures up to approximately 1000 degrees Celsius are realistic in operation, the busbar must be sufficiently thick and made of a material suitable for this temperature range.

[0030] It is also preferable if the busbar has a cross-sectional distribution that minimizes thermal expansion due to temperature fluctuations. Because of the wide temperature ranges in which the busbar is used, changes in length due to temperature influence are to be expected and must be compensated for to prevent damage to the connection points between the busbar, heating conductor, and inner conductor.

[0031] In particular, if the conductor rail has a long extension, for example as a result of the positioning of the heating conductor relative to the inner conductor, larger changes in the length of the conductor rail can occur.

[0032] Furthermore, it is advantageous if the busbar is metallurgically bonded to the inner conductor and / or the heating conductor. Preferably, the busbar is soldered to the inner conductor and the heating conductor.

[0033] Furthermore, it is advantageous if the heating conductor is formed by a honeycomb structure, with the conductor rail engaging in one or more of the flow channels of the honeycomb structure. The honeycomb structure forming the heating conductor has a plurality of flow channels through which the exhaust gas can flow along a main flow direction. In an advantageous embodiment, the conductor rail can have elements that engage in individual flow channels and are metallurgically bonded to the heating conductor. It must be ensured that the contact area of ​​the conductor rail to the heating conductor is sufficiently large to withstand the currents occurring during operation without damage.

[0034] It is also advantageous if the conductor rail has an end area facing the heating conductor, wherein the end area has at least two finger-like sections that at least partially encompass the heating conductor.

[0035] The conductor rail preferably has at least two finger-like areas that are positioned against the outer surfaces of the heating conductor and are bonded to it there. These finger-like areas grip the heating conductor like pincers. In this way, the current is transferred to the heating conductor at at least two surfaces, resulting in a more homogeneous current input and transfer to the heating conductor.

[0036] Advantageous embodiments of the present invention are described in the dependent claims and in the following description of the figures. Brief description of the drawings

[0037] The invention will now be explained in detail using exemplary embodiments and with reference to the drawings. The drawings show: Fig. 1 shows a view of an electrical feedthrough through a housing of an exhaust system with an electrical heating conductor, wherein the electrical conductor of the feedthrough is connected to the heating conductor by means of a busbar; Fig. 2 shows a sketch of a busbar for connecting the electrical conductor of a feedthrough to a heating conductor; Fig. 3 shows an alternative embodiment of a busbar in a housing of an exhaust system; Fig. 4 shows an alternative embodiment of a busbar with an axial outlet in a housing of an exhaust system; Fig. 5 shows an alternative embodiment of a busbar with a radial outlet in a housing of an exhaust system; and Fig. 6 shows an alternative embodiment of a busbar with a radially offset outlet in a housing of an exhaust system. Preferred embodiment of the invention

[0038] The Figure 1Figure 1 shows a device for exhaust gas aftertreatment 1, wherein a heating conductor 3 in the form of a honeycomb structure is arranged in a housing 2. An electrical feedthrough 11 is guided through the housing 2, which has an inner conductor 4 enclosed by an insulating layer 6.

[0039] The inner conductor 4 is connected inside the housing 2 to a busbar 5. The busbar 5 is connected on one side to the inner conductor 4 and on the other side to the heating conductor 3.

[0040] As in Figure 1As can be seen, the heating conductor 3 is positioned significantly away from the inner conductor 4. Additionally, the inner conductor 4 is positioned relative to the heating conductor 3 such that it forms a surface normal to the heating conductor 3. In embodiments known in the prior art, the inner conductor is typically positioned so that it meets a side surface of the heating conductor, with the connection of the inner conductor to the heating conductor being made via a contact on the outer circumference of the heating conductor. This results in very limited degrees of freedom for the arrangement of the individual elements.

[0041] In the case of the invention Figure 1The heating conductor 3 can be oriented arbitrarily relative to the inner conductor 4, since the gap between the two elements is bridged by the busbar 5. This significantly increases the degrees of freedom available for positioning the individual components and, in particular, makes it possible to arrange the electrical feedthrough at an advantageous location on the housing.

[0042] It can be seen how the busbar 5 projects into a plane 10 in which the heating conductor 3 is arranged. The busbar 5 is attached to the inner conductor 4, which projects through a metallic sleeve 15 of the electrical bushing 11 into a housing 2. The inner conductor 4 is surrounded by an insulating layer 6, which is in contact with and attached to the metallic sleeve 15.

[0043] Figure 2Figure 1 shows an alternative configuration of the heating conductor 5, in which the inner conductor 4, the insulation layer 6, and the heating conductor 3 are also indicated. Here, too, the inner conductor 4 acts as a surface normal to the cross-sectional area of ​​the heating conductor 3. The busbar 5 again serves as a connecting element between the two elements. The angled design of the busbar allows for a connection to the circumferential surface of the heating conductor 3, even though the inner conductor 4 is at a right angle to this circumferential surface.

[0044] In Figure 2 It can also be seen that misalignments between the inner conductor 4 and the heating conductor 3 can be easily compensated for by changing the geometry of the busbar 5. The arc-shaped section 8 forms a compensation area that can, in particular, compensate for thermal expansion of the busbar due to temperature fluctuations.

[0045] Fig. 2 It also shows a distance 19, over which the busbar 5 extends from the heating conductor 3 to the inner conductor 4. The distance 19 ranges from one end of the inner conductor 4 to the middle of the heating conductor 3. Furthermore, in Fig. 2 An offset 20 is shown. The offset 20 extends from a central axis of the inner conductor 4 to an outer side of the heating conductor 3.

[0046] Fig. 3Figure 1 shows another alternative embodiment of a busbar 5, in which it has finger-like sections 7 at the end region facing the heating conductor 3. The finger-like sections 7 rest against two circumferential surfaces of the heating conductor 3 and are metallurgically bonded to the heating conductor 3 at this point. It is also possible for plug-shaped ends of the busbar 5 to enclose and contact the heating conductor 3 at more than two points. The contact area between the heating conductor 3 and the busbar 5 is increased by the double-sided or multi-sided arrangement of the finger-like sections 7, thus ensuring that the currents occurring during operation can be transmitted safely and without damage.

[0047] It can be seen how the busbar 5 projects into a plane 10 in which the heating conductor 3 is arranged. The busbar 5 is attached to the inner conductor 4, which projects through a metallic sleeve 15 of the electrical bushing 11 into a housing 2. The inner conductor 4 is surrounded by an insulating layer 6, which is in contact with and attached to the metallic sleeve 15. The heating conductor 3 is held on a support structure 26 by support pins 24. The heating conductor 3 is attached to the support structure 26 in an insulated manner. The support pins 24 are encased in insulation 25, to which the heating conductor is held.

[0048] Also in Fig. 3 to recognize how a flow path 9 (or exhaust gas path) runs through the housing 2. The exhaust gas flow initially flows through the heating conductor 3 in level 10, and is then directed through a main catalyst 16 located outside level 10.

[0049] The housing 2 is divided into two parts. It comprises a cover 17 and a pipe section 18. The electrical feedthrough 11 is located in the cover 17. The cover also has an inlet 22 for the exhaust gas. The pipe section 18 connects seamlessly to the cover 17. The main catalyst 16 is located in the pipe section 18 behind the level 10 containing the heating element 3. The main catalyst 16 is positioned recessed within the pipe section 18 and is fixed to the pipe section 18 by means of a circumferential retaining structure 21.

[0050] Finally, it shows Fig. 3Different movements that the inner conductor 4 can transmit to the busbar 5. Thus, the inner conductor 4 can transmit axial movements 12, radial movements 13, and / or torsional movements 14 simultaneously or individually to the busbar 5. It is also possible for the movements described above to be transmitted from the heating conductor 3 to the busbar 5. In particular, the busbar 5 is designed to absorb these movements and the associated forces without sustaining damage and to return to its original position after the force has been applied.

[0051] An alternative design of a conductor rail 5 shows Fig. 4. Fig. 4 has a similar housing 2 as in Fig. 3a flow path 9 is guided perpendicularly to the heating conductor 3 into the housing 2 and then through the heating conductor 3. The inner conductor 4 of the electrical feedthrough is arranged such that the busbar 5 projects straight downwards. The busbar 5 is designed as an extension of the inner conductor 4. The busbar 5 also has an arc-shaped section 8. In particular, the alternative embodiment differs in Figure 4 in terms of its design in Figure 3 that the conductor rail 5, apart from the arc-shaped section 8, has no axial offset along a central axis of the inner conductor 4. In contrast, the design of the conductor rail 5 in Figure 3 an axial offset.

[0052] An alternative design of a conductor rail 5 shows Fig. 5. Fig. 5 has a similar housing 2 as in Fig. 3 and Fig. 4a flow path 9 is guided perpendicularly to the heating conductor 3 into the housing 2 and then through the heating conductor 3. The inner conductor 4 of the electrical feedthrough is arranged such that the busbar 5 projects vertically downwards from the inner conductor 4. Connection to a heating conductor 3 is thus made perpendicular to the inner conductor 4. The inner conductor 4 may have a central axis that intersects a central axis of the heating conductor 3. The busbar 5 also has an arc-shaped section 8. In particular, Fig. 5 A configuration of the conductor rail 5 without axial offset, apart from the arc-shaped section 8. The inner conductor 4 projects into the housing 2 to such an extent that the conductor rail 5 extends downwards in a straight line. However, it is also possible that the conductor rail 5 is configured as shown in Fig. 3 exhibits an axial offset.

[0053] An alternative design of a conductor rail shows Fig. 6. Fig. 6 The housing has a configuration in which the heating conductor 3 is arranged transversely to the flow path 9. The inner conductor 4 projects transversely to the heating conductor 3 into the housing 2 at the level of the heating conductor 3. The configuration in Fig. 6 differs in particular from the design in Fig. 5 The inner conductor 4 is not arranged at a height offset within the housing 2. The inner conductor 4 is arranged relative to the busbar 5 such that the busbar 5 is perpendicular to the inner conductor 4 along a circumferential direction of the heating conductor 3. Thus, the busbar 5 does not bridge a height offset parallel to a central axis of the heating conductor 3, but only an offset along the circumference of the heating conductor 3. Furthermore, the busbar 5 does not have an arc-shaped section 8.

[0054] The examples of implementation of Figures 1 to 6In particular, they do not have a restrictive character and serve to clarify the inventive idea. Reference symbol list

[0055] 1 Exhaust aftertreatment device 2 Housing 3 Heating element 4 Inner conductor 5 Current conductor rail 6 Insulation layer 7 Finger-like sections 8 Arc-shaped section 9 Flow path 10 Plane 11 Electrical feedthrough 12 Axial movement 13 Radial movement 14 Torsional movement 15 Metallic sleeve 16 Main catalyst 17 Cover 18 Pipe section 19 Distance 20 Offset 21 Retaining structure 22 Inlet 23 Contact section 24 Support pin 25 Insulation 26 Support structure

Claims

1. Device (1) for the aftertreatment of exhaust gases of an internal combustion engine with at least one electrical heating conductor (3) which is arranged in a plane (10) inside a flow path (9) bounded by a housing (2), wherein the at least one heating conductor (3) can be electrically contacted by means of at least one electrical feedthrough (11) through the housing (2), and the at least one heating conductor (3) is electrically connected to the at least one electrical feedthrough (11) inside the housing (2) by means of at least one busbar (5), characterized by the fact that which contacts at least one conductor rail (5), at least one electrical feedthrough (11) outside the plane (10) and at least one heating conductor (3) in the plane (10) and radially offset.

2. Device (1) for the aftertreatment of exhaust gases of an internal combustion engine according to claim 1, wherein the at least one conductor rail (5) is or comprises a bending element for compensating axial (12), radial (13) and / or torsional (14) relative movements of the at least one heating conductor (3) with respect to the at least one electrical feedthrough.

3. Device (1) for the aftertreatment of exhaust gases of an internal combustion engine according to one of the preceding claims, wherein the at least one conductor rail surrounds the at least one heating conductor (3).

4. Device (1) for the aftertreatment of exhaust gases of an internal combustion engine according to one of the preceding claims, wherein the at least one electrical heating conductor (3) is attached to a planar support structure (26) and the at least one conductor rail (5) extends through the support structure (26).

5. Device (1) for the aftertreatment of exhaust gases of an internal combustion engine according to one of the preceding claims, wherein the electrical feedthrough has an inner conductor (4) which is surrounded by an electrical insulating layer (6) and a metallic sleeve (15).

6. Device (1) according to one of the preceding claims, wherein the inner conductor (4) is aligned perpendicular to the plane (10).

7. Device (1) according to one of the preceding claims, wherein the conductor rail (5) is aligned parallel to the plane (10) in a connection area with the inner conductor (4).

8. Device (1) according to one of the preceding claims, wherein each inner conductor (4) has a conductor rail (5).

9. Device (1) according to one of the preceding claims, wherein the conductor rail (5) has a contact section (23) in which the inner conductor (4) is connected to the conductor rail (5), wherein the conductor rail (5) extends in the contact section (23) only in a radial direction relative to the inner conductor (4).

10. Device (1) according to one of the preceding claims, wherein the conductor rail (5) has a cross-sectional distribution which reduces longitudinal expansions due to temperature fluctuations.

11. Device (1) according to one of the preceding claims, wherein the heating conductor (3) is formed by a honeycomb body, wherein the current conductor (5) engages in one or more of the flow channels of the honeycomb body.

Images