Apparatus and method for heating a device for exhaust gas after-treatment

Abstract

An apparatus for heating an exhaust gas after-treatment unit in a vehicle has, as a drive source, both a combustion engine and an electric motor. The apparatus includes: a honeycomb body configured for exhaust gas to flow therethrough, the honeycomb body having a hollow, through which hollow the exhaust gas flows; and at least one electric heating element arranged in the hollow so as to heat the honeycomb body. The honeycomb body includes a plurality of metal foils stacked one on top of the other, which metal foils form between them a plurality of flow channels, through which a flow can pass along an axial direction, wherein the hollow of the honeycomb body extends in a radial direction, in which the at least one heating element is accommodated.

Claims

1. An apparatus for heating an exhaust gas after-treatment unit in a vehicle having, as a drive source, both a combustion engine and an electric motor, the apparatus comprising: a honeycomb body (5) configured for exhaust gas to flow therethrough, the honeycomb body (5) comprises: a plurality of metal foils stacked one on top of the other, which metal foils form between them a plurality of flow channels, through which a flow can pass along an axial direction; and a hollow (6) that extends radially through a first portion of the plurality of metal foils stacked one on top of the other; and at least one electric heating element (1, 7) arranged in the hollow (6) so as to heat the honeycomb body (5), wherein the hollow (6) of the honeycomb body (5) extends in a radial direction, in which the at least one heating element (1, 7) is accommodated, wherein a second portion of the plurality of metal foils stacked one on top of the other are not interrupted by the hollow.

2. The apparatus as claimed in claim 1, wherein the heating element (1, 7) is operable at a system voltage of 12 volts up to a maximum of 48 volts.

3. The apparatus as claimed in claim 1, wherein the heating element (1, 7) is operable at a system voltage above an onboard voltage in a vehicle operated with only a combustion engine.

4. The apparatus as claimed in claim 1, further comprising a shell (8) surrounding the honeycomb body (5), wherein, when viewed from the outside to the inside of the apparatus in the radial direction, the heating element (1, 7) has: a first region (2) in contact with the shell (8), a thermal insulating region (3), and a heating zone (4).

5. The apparatus as claimed in claim 1, further comprising an electrically heatable heating disk arranged ahead of the honeycomb body (5) in a flow direction of the exhaust gas.

6. The apparatus as claimed in claim 5, wherein the heating element (1, 7) in the honeycomb body (5) and the heating disk are heatable independently of one another.

7. The apparatus as claimed in claim 1, wherein the first portion of the plurality of metal foils stacked one on top of the other are deformed at least where they contact the at least one electric heating element (1, 7).

8. The apparatus as claimed in claim 7, wherein the first portion of the plurality of metal foils stacked one on top of the other are deformed in a direction of insertion of the at least at least one electric heating element (1, 7).

9. A method for heating the exhaust gas after-treatment unit, using the apparatus as claimed in claim 5, the method comprising heating the exhaust gas after-treatment unit by at least two different heating methods, wherein the respective heating method is selected according to the respective drive source being used to produce propulsion of the vehicle.

10. The method as claimed in claim 9, wherein, when the combustion engine is used as the drive source, the exhaust gas after-treatment unit is heated by the heating disk positioned ahead of the honeycomb body (5), wherein the exhaust gas stream flowing through the heating disk is heated by the heating disk, and the heated exhaust gas stream subsequently heats the honeycomb body (5).

11. The method as claimed in claim 10, wherein, when the electric motor is being used as the drive source, the exhaust gas after-treatment unit is heated by the heating element (1, 7) arranged in the hollow (6) of the honeycomb body (5).

12. The method as claimed in claim 11, wherein the heating element (1, 7) is heated with a voltage of approximately 230 volts or more, thereby achieving a power output of up to 300 watts, at current intensities of 1 to 1.5 amps.

13. The method as claimed in claim 11, wherein the heating of the honeycomb body (5) by the heating element (1, 7) takes place continuously for as long as the combustion engine is not being operated.

14. The method as claimed in claim 13, further comprising providing a controller configured to monitor the vehicle, which, the controller being further configured to, depending on the respectively active drive source and the instantaneous driving situation, produce a prediction of the type of drive selected in the future, wherein, in the event of an expected use of the combustion engine as the drive source, the heating of the honeycomb body (5) by the heating element (1, 7) is started.

15. The method as claimed as claimed in claim 13, further comprising preheating the heating element, wherein the preheating can be started by a timer or by an external control element, based on values acquired by a monitoring unit.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be explained in detail in the following on the basis of exemplary embodiments with reference to the drawings, in which:

(2) FIG. 1 shows a schematic sectional illustration through a heating element; and

(3) FIG. 2 shows a schematic sectional illustration through a honeycomb body having a heating element.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

(4) FIG. 1 shows a schematic sectional illustration through a heating element 1. The heating element 1 is divided into three regions. The “cold” end 2, which forms the mounting region of the heating element 1. By this region 2, the heating element 1 can be secured on the shell of a honeycomb body and thus positioned in a hollow of the honeycomb body.

(5) Below this, region 3 illustrates a thermal insulating region, which produces thermal insulation between the heating region 4, illustrated below it, and the mounting region 2. The heating region 4 may also be referred to as a heating zone.

(6) The entire heating element 1 is of pin-shaped design and can preferably be inserted into a honeycomb body in a radial direction. The thermal insulating region 3 reduces the heat released by the heating element 1 toward the mounting region 2, thereby simultaneously also reducing the heat losses toward the mounting region 2 and furthermore toward the outside of the honeycomb body. All the heat produced in the heating region 4 can therefore advantageously be released to the honeycomb structure of the honeycomb body, thereby achieving more effective heating overall.

(7) The heating element 1 has an electric conductor 9, which is passed through the mounting region 2 and the thermal insulating region 3 into the heating region 4 through a channel-type structure 10 in the interior of the heating element 1. The electric conductor 9 is electrically insulated from the mounting region 2 and the thermal insulating region 3.

(8) FIG. 2 shows a section through a honeycomb body 5 produced from stacked metal foils. In this case, the metal foils have holes which, in the fully assembled state, i.e., when the foil stack has been wound up to form the honeycomb body 5, are in line with one another and thus form the hollow 6 extending in the radial direction through the honeycomb body. The heating element 7 is inserted from the outside into this hollow 6.

(9) Just as in the case of the heating element shown in FIG. 1, the heating element 7 has three regions, wherein, in particular, the mounting region, by which the heating element is secured on the shell 8 of the honeycomb body 5, is separated from the heating region by thermal insulation. The appropriate heating of the honeycomb body 5 is thereby achieved with the smallest possible heat losses.

(10) The exemplary embodiments in FIGS. 1 and 2 are in particular not of a limiting nature, and serve for illustrating the concept of the invention.

(11) Although exemplary embodiments have been discussed in the above description, it should be noted that numerous modifications are possible. Furthermore, it should be noted that the exemplary embodiments are merely examples which are not intended to limit the scope of protection, the applications and the structure in any way. Rather, a person skilled in the art will take from the above description a guideline for implementation of at least one exemplary embodiment, wherein various modifications may be made, in particular with regard to the function and arrangement of the described components, without departing from the scope of protection as can be gathered from the claims and equivalent feature combinations.