Exhaust gas after-treatment arrangement and method for operating such an arrangement

Abstract

Exhaust gas after-treatment arrangement and method for operating an exhaust gas after-treatment arrangement

The invention relates to an exhaust gas after-treatment arrangement having an exhaust line 1 and at least one exhaust gas after-treatment device 2, which has a honeycomb body 5 forming a flow surface for the exhaust gas. The honeycomb body 5 is a hollow cylinder having a central channel 7, wherein the one movable element 9, 15 is arranged in such a way that the movable element can be moved between two end positions, wherein in the first end position a larger cross section of the channel 7 is exposed than in the second end position.

Claims

1-20. (canceled)

21. An exhaust gas after-treatment assembly comprising: an exhaust line (1); and at least a first exhaust gas after-treatment device (2) having a honeycomb body (5) forming a flow surface for the exhaust gas, wherein the honeycomb body (5) is a hollow cylinder having a central channel (7) having an inlet (7), a movable dement (9, 15) is arranged such that the movable element (9, 15) is movable between first and second end positions, wherein when the movable element (9, 15) is in the first end position a larger cross section of the channel (7) is exposed than when the movable element (9, 15) is in the second end position.

22. The exhaust gas after-treatment assembly as claimed in claim 21, wherein the first end position exposes at least 75% of the channel cross section.

23. The exhaust gas after-treatment assembly as claimed in claim 22, wherein the second end position closes at least 75% of the channel cross section.

24. The exhaust gas after-treatment assembly as claimed in claim 21, wherein the first end position exposes at least 75% of the channel cross section.

25. The exhaust gas after-treatment assembly as claimed in claim 21, wherein the movable element (9) is movable in a rotary manner.

26. The exhaust gas after-treatment assembly as claimed in claim 25, wherein the movable element is a rotatable flap (9).

27. The exhaust gas after-treatment assembly as claimed in claim 24, wherein the movable element (15) is movable in translation.

28. The exhaust gas after-treatment assembly as claimed in claim 27, wherein the movable element is a slide (15).

29. The exhaust gas after-treatment assembly as claimed in claim 27, wherein the movable element is a rigid slide (15).

30. The exhaust gas after-treatment assembly as claimed in claim 27, wherein the movable element is a flexible slide.

31. The exhaust gas after-treatment assembly as claimed is claim 27, wherein the movable element comprises a plurality of movable blades.

32. The exhaust gas after-treatment assembly as claimed in claim 21, wherein the movable element (9, 15) is held and/or guided in the honeycomb body (5).

33. The exhaust gas after-treatment assembly as claimed in claim 31, wherein the movable element (9, 15) is held and/or guided in the exhaust line (1).

34. The exhaust gas after-treatment assembly as claimed in claim 21, wherein the movable element (9, 15) is arranged in a region of the inlet (8) of the channel (7) in the flow direction.

35. The exhaust gas after-treatment assembly as claimed in claim 33, wherein the movable element (9, 15) is arranged in the region of an outlet (13) of the channel (7) in the flow direction.

36. The exhaust gas after-treatment assembly as claimed in claim 21, further comprising an electric motor (11) configured to drive the movable element (9, 15).

37. The exhaust gas after-treatment assembly as claimed in claim 21, further comprising a connecting rod (16) that is subjected to pressure and a spring force and is connected to the movable element (9, 15).

38. The exhaust gas after-treatment assembly as claimed in claim 21, further comprising a second exhaust gas after-treatment device arranged downstream of the first exhaust gas after-treatment device.

39. A method for operating an exhaust gas after-treatment assembly as claimed in claim 21, comprising: moving the movable element toward the second end position in the case of low exhaust gas flows; and moving the movable element toward the first end position in the case of higher exhaust gas flows.

40. The method as claimed in claim 29, wherein the movable element is movable into intermediate positions between the first and second end positions.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The invention will be explained in more detail by way of a plurality of exemplary embodiments. In the figures:

[0029] FIG. 1 is a schematic illustration of an exhaust gas after-treatment arrangement;

[0030] FIG. 2 shows the exhaust gas after-treatment arrangement according to FIG. 1 in a different operating state;

[0031] FIG. 3 shows further arrangements of the movable element; and

[0032] FIGS. 4-7 show further embodiments of the movable element.

DETAILED DESCRIPTION OF THE PRESENTLY PREFERRED EMBODIMENTS

[0033] FIG. 1 shows a section of an exhaust line 1 in which a catalytic converter acting as an exhaust gas after-treatment device 2 is arranged. Another exhaust gas after-treatment device 3, which is likewise configured as a catalytic converter, is arranged downstream of catalytic converter 2. Catalytic converter 2 has a casing 4, which surrounds a honeycomb body 5. The honeycomb body 5 is formed by a plurality of sheet metal layers, which form a catalyst matrix 6 and is a flow surface for the exhaust gas, wherein a catalytic reaction takes place in the exhaust gas as it flows through the catalyst matrix 6. Along its longitudinal axis, the honeycomb body 5 has a central channel 7, through which exhaust gas can flow, bypassing the catalyst matrix 6. The main flow direction of the exhaust gas is indicated by an arrow. Situated at the inlet 8 of the channel 7 is a movable element 9, which blocks the inlet 8 in the illustration shown. The movable element is a flap 9, which is secured on a shaft 10. The shaft 10 is connected to the electric motor 11 acting as a drive, allowing the flap 9 to be rotated by activation of the electric motor 11. In the position shown, the flap 9 is in the second end position. The inflowing exhaust gas is directed almost completely onto the catalyst matrix 6 and flows through the catalyst matrix 6. The flap 9 is moved into this end position at low exhaust gas mass flows, at which the catalyst matrix 6 is sufficiently large to ensure that the exhaust gas flowing through builds up almost no disruptive backpressure.

[0034] In the illustration shown in FIG. 2, the flap 9 has been rotated through 90 by the electric motor 11 and thus moved into the first end position, as a result of which the maximum possible cross section of the channel 7 is exposed. The flap 9 adopts this alignment at maximum exhaust gas mass flows. Some of the exhaust gas can flow unhindered through the honeycomb body 5 via the channel 7 in a kind of bypass. Only that portion of the exhaust gas flow which flows radially outward in the exhaust line 1 impinges upon the catalyst matrix 6 and flows through the catalyst matrix 6. That portion of the exhaust gas, which flows through the channel 7 and is not subject to after-treatment impinges downstream upon a second catalytic converter 3, which does not have a bypass channel, with the result that the entire exhaust gas flow must flow through the catalyst matrix for after-treatment. Owing to the almost unhindered flow through the channel 7, this portion of the exhaust gas flow releases little heat to the honeycomb body 5. As a result, the exhaust gas contains significantly more heat than if it had flowed through the catalyst matrix 6. The heat carried further along in this way is released at the second catalytic converter 3 by this exhaust gas flow. As a result, the second catalytic converter 3 warms up more quickly and the catalytic reaction tor exhaust gas after-treatment starts more quickly.

[0035] FIG. 3 shows a further arrangement of the movable element 9 in the honeycomb body 5, in which no additional installation space is required for the exhaust gas after-treatment arrangement 12 according to the invention as compared with a conventional honeycomb body 5.

[0036] In the case of the arrangement of the movable element 9 in FIG. 4, this element is arranged at the outlet 13 of the channel 7. The mounting for the movable element 9 is situated in the exhaust line 1, which has a separate section 14 in this region. In the illustration shown, the channel 7 is closed, although closed should not be taken to involve gastight sealing. The low leakage rates are negligible but, in return, allow significantly simpler and thus economical arrangement of the exhaust gas after-treatment device 2 relative to the movable element 9. As in FIG. 1, the element 9 adopts this alignment at low exhaust gas mass flows. In this case, a large part of the exhaust gas initially flows into the channel 7 before the exhaust gas, which then flows in behind is directed into the catalyst matrix 6. Owing to its dwell time in the channel 7, the exhaust gas in the channel 7 brings about significantly quicker heating up of the honeycomb body 5.

[0037] FIG. 5 shows the honeycomb body 5 with a rigid slide 15. The slide 15 is connected to an electric motor 11 by a connecting rod 16. The electric motor 11 drives the rod 16, thus allowing the slide 15 to be moved perpendicularly to the longitudinal axis of the honeycomb body 5 through the translational movement of the slide. In the illustration shown, the slide 15 is in the first end position and exposes 80% of the cross section of the channel 7.

[0038] FIGS. 6 and 7 show further embodiments, wherein, in FIG. 6, the movable element 9 is connected to a pivoting arm 17, which can be pivoted about a pivoting axis 18. The pivoting axis 18 is connected as a shaft 10 to a drive 11. In order to influence the channel cross section and hence the gas flow as little as possible, the pivoting axis 18 is arranged on the wall of the exhaust line 1 and thus outside the main flow. To close the channel 7, the movable element s has a closure plug 19 in the form of a spherical cup. which is connected to the pivoting arm 17. In order to keep the effect on the flow cross section small, it is conceivable to enlarge the cross section of the exhaust line 1 such that the enlargement 20 at least partially accommodates the movable element 9 that can be pivoted away from the catalytic converter 2.

[0039] The movable element 9 in FIG. 7 likewise has a closure plug 19 in the form of a spherical cup, which closes the channel 7. In the region of the movable element, the exhaust line is curved, and therefore the slide 21, which is connected to the closure plug 19 in a manner that allows it to move in translation, is passed to the outside through the exhaust line if it is arranged as an extension of the axis of rotation of the catalytic converter 2. The slide 21 is moved by a drive (not shown), which is situated outside the exhaust line 1.

[0040] Thus, while there have been shown and described and pointed out fundamental novel features of the invention as applied to a preferred embodiment thereof, it will be understood that various omissions and substitutions and changes in the form and details of the devices illustrated, and in their operation, may be made by those skilled in the art without departing from the spirit of the invention. For example, it is expressly intended that all combinations of those elements and/or method steps which perform substantially the same function in substantially the same way to achieve the same results are within the scope of the invention. Moreover, it should be recognized that structures and/or elements and/or method steps shown and/or described in connection with any disclosed form or embodiment of the invention may be incorporated in any other disclosed or described or suggested form or embodiment as a general matter of design choice. It is the intention, therefore, to be limited only as indicated by the scope of the claims appended hereto.