JP7614263B2 - Heating elements for use in automotive exhaust aftertreatment systems - Google Patents

Description

The present invention relates to a heating element for use in an exhaust gas aftertreatment system of a motor vehicle, to an exhaust gas aftertreatment system including such a heating element, and to a motor vehicle using such a heating element or such an exhaust gas aftertreatment system.

Vehicles with internal combustion engines require exhaust gas aftertreatment in order to comply with legally established exhaust gas emissions. The components responsible for exhaust gas aftertreatment (especially the catalytic converter and the particle filter) reach their light-off temperature, if possible, immediately after the start of cooling, so that the aftertreatment of the emitted exhaust gases can begin immediately after starting. However, the heating of the exhaust gas aftertreatment components is typically achieved indirectly by the thermal energy present in the exhaust gas stream, which requires some time to heat up the components in question. However, in order to achieve even stricter exhaust gas limits in the future, future exhaust systems must be able to optimally treat the exhaust gases at any time, even immediately after a cold start.

To avoid engine operating points without active exhaust gas aftertreatment, such as after a cold start of the engine or below or above a defined ambient temperature, it is known to either transfer thermal energy generated from electrical energy to the exhaust gas stream (for subsequent heating of exhaust gas aftertreatment components) or to insert an electrically heatable body into the exhaust gas stream, which itself is provided with a catalytic coating, thereby causing self-heating exhaust gas aftertreatment components to self-heat (e.g. like a heated catalyst).

In this regard, it has been found to be particularly advantageous to use heating elements made from thermal conductors aligned relative to one another, with continuous gaps for insulation between adjacent thermal conductors.

However, unfortunately, areas of the heating element with gaps have a lower flow resistance compared to areas without gaps, and therefore flow preferentially passes through the gaps, resulting in a high percentage of the total flow being bypassed depending on the gap width, resulting in ineffective and insufficient heating of the exhaust gas aftertreatment components and/or ineffective and insufficient catalytic aftertreatment of the exhaust gas aftertreatment components.

The problem addressed by the present invention is therefore to at least partially remedy the above-mentioned disadvantages. In particular, the problem addressed by the present invention is to provide a heating element consisting of individual heat conductors with gaps extending between the heat conductors for use in exhaust gas aftertreatment systems of automobiles, which allows for rapid and effective heating of exhaust gas aftertreatment components and/or rapid and effective catalytic aftertreatment of the exhaust gas stream.

The above-mentioned object is achieved by a heating element having the features according to claim 1, an exhaust gas aftertreatment system having the features according to claim 9 and a vehicle having the features according to claim 10. Further features and details of the invention result from the subclaims, the description and the drawings. The technical features and details disclosed in relation to the heating element according to the invention naturally also apply in relation to the exhaust gas aftertreatment system according to the invention and the vehicle according to the invention and vice versa, so that reference is always made to each other or can be made to each other with regard to the disclosures relating to the individual aspects of the invention.

According to the present invention, there is provided a heating element for use in an exhaust gas aftertreatment system of an automobile. The heating element comprises a plurality of fluid-perfusable heat conductors for heating an exhaust gas stream or for catalytic aftertreatment of an exhaust gas stream, a plurality of gaps, the plurality of gaps being disposed between the heat conductors and having a perfusable cross-section for passing the exhaust gas stream, and ribs being disposed within the gaps to constrict the perfusable cross-section.

According to the invention, the presented heating element is therefore configured to allow rapid and effective heating and/or catalytic aftertreatment of the exhaust gas flow by being provided by a combination of a plurality of fluid-perfusable heat conductors and gaps arranged between the heat conductors and having a perfusable cross-section with gap ribs. In contrast to known heating elements for use in automotive exhaust gas aftertreatment systems, which consist of individual heat conductors with gaps extending between them, it is possible by the arrangement of the ribs (gap ribs) provided by the invention to reduce the perfusable cross-section in the gap so that the flow resistance in the gap is the same as the area outside the gap, so that the exhaust gas flow passing through the heating element passes evenly through the surface or volume of the heating element, thereby making it possible to achieve effective heating and/or catalytic aftertreatment of the exhaust gas flow.

The proposed heating element can be suitably used in vehicles having an internal combustion engine, such as, for example, a passenger car or truck driven by an internal combustion engine. However, it is also contemplated that the proposed heating element can be used in internal combustion engines, such as aircraft or ships. In the context of the present invention, a fluid-perfusable heat conductor is understood to be, in particular, a heat conductor through which a fluid, such as a gas or liquid, can flow, in particular in an exhaust gas flow. For this purpose, the heat conductor preferably has a lattice-like structure with recesses for passing a fluid. It is preferred to configure the heat conductor in the form of an electric heat conductor through which an electric current can pass by application of a voltage and generate heat via the flow of electric current. In addition, in the present case, the gap may be understood to be a crack-shaped or elongated opening or recess, which may preferably serve for the electrical insulation of two adjacent heat conductors. The perfusable cross section may then form, in particular, an opening surface or a recessed surface. In the context of the present invention, a rib for constricting the perfusable cross section may be understood to mean, in particular, a rod-like or bolt-like element or protrusion that narrows the fluid-perfusable cross section of the gap.

In order to heat the exhaust gas flow as quickly and effectively as possible, it may be advantageously provided in the present case that the heat conductor comprises fluid-permeable channels for passing the exhaust gas flow, the heat conductor preferably comprising a lattice structure with the fluid-permeable channels arranged in the lattice structure. Effective heating or catalytic post-treatment may occur via contact of the particles of the exhaust gas flow with the lattice structure.

As part of the effective contraction of the perfusable cross section of the presented gap, it is advantageous if the ribs are arranged on the outside of the heat conductor in the gap, the ribs being preferably arranged in the gap perpendicular to the main orientation axis of the gap, and the ribs arranged on two heat conductors arranged adjacent to each other in the gap are arranged at least partially opposite each other. The ribs can be arranged on the outer wall of the heat conductor, the outer wall directly abutting the gap. A vertical arrangement in the context of the present invention can also be understood to mean a substantially vertical arrangement, preferably with a smaller deviation from the ideally vertical arrangement, for example <5°, preferably <3°, in particular <1°.

Alternatively, as part of the effective reduction of the perfusable cross section of the presented gap, it is also advantageously provided that the ribs are arranged on the outside of the heat conductors in the gap, the ribs being preferably arranged in the gap perpendicular to the main orientation axis of the gap, and the ribs arranged on two heat conductors arranged adjacent to each other in the gap are arranged at least partially offset from each other. In this case, the ribs are preferably arranged and configured relative to each other such that the heat conductors arranged adjacent to each other do not come into contact with each other in order not to create an undesirable short circuit when a voltage is applied to the heating element.

Furthermore, as part of the effective contraction of the perfusable cross-section, it may be advantageous when the ribs have a wedge-like structure, the ribs being arranged at least partially opposite one another in the gap, and the oppositely arranged ribs (or ribs arranged adjacent to one another in an offset manner) being arranged one behind the other in an offset manner. Such an arrangement can, for example, create flow paths that guide the flow of exhaust gas past the current heat conductor in a targeted manner.

With regard to the avoidance of short circuits between two heat conductors arranged adjacent to one another, it may advantageously be further provided that the ribs are at least partially formed from a non-conductive material, the ribs preferably being formed from plastic or ceramic.

Alternatively, as part of a stable and compact arrangement, it may be advantageous if the ribs are materially uniform with the thermal conductor, and preferably are integrally formed therewith. Thus, in the context of such a design, the ribs may be made from a conductive material, such as a metallic material.

To ensure direct catalytic post-treatment of the exhaust gas stream via the proposed heating element itself, it is further contemplated that the heat conductor comprises a catalytically effective coating for catalytic post-treatment of the exhaust gas stream.

The subject of the invention is also an exhaust gas aftertreatment system according to the invention for use in a motor vehicle. The exhaust gas aftertreatment system according to the invention comprises at least one heating element as described above, a conduit system for directing the exhaust gas flow, and exhaust gas aftertreatment components such as at least one catalyst for the aftertreatment of the exhaust gas flow and one exhaust gas particle filter. The exhaust gas aftertreatment system according to the invention therefore offers the same advantages as described above for the heating element according to the invention. As part of an effective exhaust gas aftertreatment, it can be advantageously provided that at least two of the presented heating elements arranged parallel to one another, two conduit systems arranged parallel to one another for guiding the exhaust gas flow, and two exhaust gas aftertreatment components arranged parallel to one another (in each case at least one catalyst and one exhaust gas particle filter) are arranged in the exhaust gas aftertreatment system.

A further subject of the invention is a motor vehicle having a heating element as described above and preferably having an exhaust gas aftertreatment system as described above. The motor vehicle according to the invention therefore has the same advantages as have already been broadly described for the heating element according to the invention and the exhaust gas aftertreatment system according to the invention.

Further advantages, features and details of the invention arise from the following specification, in which exemplary embodiments of the invention are described in detail with reference to the drawings. The features mentioned in the claims and in the specification may be essential to the invention individually or in any combination.

1 is a plan view of a heating element according to the invention for use in an exhaust gas aftertreatment system of a motor vehicle according to a first embodiment; FIG. 2 is a cross-sectional view of a heating element according to the invention for use in an exhaust gas aftertreatment system of a motor vehicle according to FIG. 1, without the indication of a rib provided in the gap according to the invention; 2 is a half-sectional view of a heating element according to the invention for use in an exhaust gas aftertreatment system of a motor vehicle according to FIG. 1 with indication of a rib provided in the gap according to the invention; FIG. 1 is an exhaust gas aftertreatment system according to the invention for use in a motor vehicle.

Figure 1 shows a plan view of a heating element 2 according to the present invention for use in an exhaust gas aftertreatment system 1 of a motor vehicle according to a first embodiment.

As can be seen from FIG. 1, the heating element 2 comprises a number of fluid-perfusable heat conductors 4 for heating the exhaust gas flow or for catalytic post-treatment of the exhaust gas flow, and a number of gaps 6 arranged between the heat conductors 4 with a perfusable cross section for passing the exhaust gas flow (starting from the fluid inlet side FE), with ribs 8 arranged in the gaps 6 to constrict the perfusable cross section, as shown enlarged on the right side of FIG. 1.

As can be seen in the enlarged area on the left side of FIG. 1, the heat conductor 4 includes fluid-permeable channels 10 for the passage of the exhaust gas flow, and the heat conductor 4 has a grid-like structure with the fluid-permeable channels 10 arranged in the grid-like structure.

As can be seen from the close-up on the right side of FIG. 1, the ribs 8 are arranged on the exterior of the thermal conductors 4 within the gaps 6, in this case perpendicular to the main orientation axis L of the gaps 6, and the ribs 8 arranged on the two thermal conductors 4 arranged adjacent to each other within the gaps 6 are arranged at least partially opposite each other.

However, it is alternatively possible for the ribs 8 arranged on two heat conductors 4 arranged adjacent to each other in the gap 6 to be arranged at least partially offset from each other.

Figure 2 shows a cross-sectional view of a heating element 2 according to the invention for use in an automotive exhaust gas aftertreatment system 1 according to Figure 1, without showing the rib 8 provided in the gap 6 according to the invention.

As can be seen in FIG. 2, the exhaust gas flow can pass through the presented heating element 2 from the fluid inlet side FE to the fluid outlet side FA.

Figure 3 shows a half cross-sectional view of a heating element 2 according to the invention for use in an automotive exhaust gas aftertreatment system 1 according to Figure 1 with the indication of a rib 8 provided in the gap 6 according to the invention.

As can be seen from FIG. 3, according to the representation from FIG. 3, the ribs 8 have a wedge-shaped structure, and the ribs 8 arranged opposite each other are arranged in an offset manner, next to each other, as well as behind each other.

The ribs 8 may be at least partially formed from a non-conductive material, such as, for example, from plastic or ceramic.

Similarly, the ribs 8 may be materially uniform with the thermal conductor 4, may be integrally formed with the thermal conductor 4, or the ribs 8 may be formed from a metallic material.

The heat conductor 4 may also be provided with a catalytically active coating for catalytic aftertreatment of the exhaust gas stream.

Figure 4 shows an exhaust gas aftertreatment system 1 according to the present invention for use in an internal combustion engine 18 of a motor vehicle.

As can be seen from FIG. 4, the exhaust gas aftertreatment system 1 comprises first and second heating elements 2 arranged parallel to one another, first and second conduit systems 12 arranged parallel to one another for directing the exhaust gas flow, and first and second exhaust gas aftertreatment components 14 for the aftertreatment of the exhaust gas flow (e.g., in each case one catalyst and one exhaust gas particle filter).

The above description of the embodiments illustrates the invention only in the context of examples. Naturally, the individual features of the embodiments may be freely combined with one another, where this is technically meaningful, without departing from the scope of the invention.

Claims (6)

A heating element (2) for use in an exhaust gas aftertreatment system (1) of a motor vehicle, comprising:
- a plurality of fluid-perfused heat conductors (4) for heating the exhaust gas stream or for catalytic aftertreatment of the exhaust gas stream,
a plurality of gaps (6) arranged between said heat conductors (4) and having a perfusable cross section for passing said exhaust gas flow, and ribs (8) arranged in said gaps (6) for constricting said perfusable cross section ,
the heat conductor (4) comprises fluid-permeable channels (10) for the passage of the exhaust gas flow, the heat conductor (4) having a grid-like structure including fluid-permeable channels (10) arranged in a grid-like structure,
The heating element (2), characterized in that the ribs (8) are arranged on the exterior of the heat conductors (4) within the gap (6), the ribs (8) are arranged in the gap (6) perpendicular to the main orientation axis (L) of the gap (6), and the ribs (8) arranged on two heat conductors (4) arranged adjacent to each other in the gap (6) are arranged without facing each other . 2. Heating element (2) according to claim 1, characterized in that the ribs (8) are at least partially made of a non-conductive material, the ribs (8) being made of plastic or ceramic. 2. Heating element (2) according to claim 1, characterized in that the ribs (8) are made of the same material as the heat conductor (4) and are formed integrally therewith. The heating element (2) according to claim 1, characterized in that the heat conductor (4) is provided with a catalytically active coating for catalytic aftertreatment of the exhaust gas stream. An exhaust gas aftertreatment system (1) for use in a motor vehicle, comprising:
- at least one heating element (2) according to claim 1,
- a conduit system (12) for directing the exhaust gas flow,
an exhaust gas aftertreatment component (14) for the aftertreatment of an exhaust gas stream. A motor vehicle equipped with an exhaust gas aftertreatment system (1) according to claim 5 .