Annular catalytic converter

Abstract

An annular catalytic converter, having a first, tubular flow path, having a diverting region and having a second, annular flow path, wherein the tubular flow path is formed by an inner pipe, wherein the annular flow path is formed between the inner pipe and an outer pipe surrounding the inner pipe, and the diverting region is of pot-shaped form for the purposes of diverting the exhaust-gas flow from the tubular flow path into the annular flow path, wherein the inner pipe and/or the outer pipe has a conical cross section that widens or narrows along the flow direction of the exhaust gas.

Claims

1. An annular catalytic converter, comprising: an inner pipe; an outer pipe, the inner pipe and the outer pipe are the same length; a tubular flow path formed by the inner pipe; an annular flow path formed between the inner pipe and the outer pipe, and surrounding the inner pipe; and a diverting region for diverting exhaust-gas flow from the tubular flow path into the annular flow path, the diverting region having pot-shaped form; a first cross-sectional area at the gas inlet side of the tubular flow path; a second cross-sectional area at the gas outlet side of the annular flow path; a third cross-sectional area at the gas outlet side of the tubular flow path; and a fourth cross-sectional area at the gas inlet side of the annular flow path; wherein each of the inner pipe and the outer pipe are conically-shaped, which widen or narrow along the flow direction of the exhaust gas, such that the tubular flow path widens conically from its gas inlet side to its gas outlet side by a first angle, and the annular flow path narrows conically from its gas inlet side to its gas outlet side by a second angle.

2. The annular catalytic converter of claim 1, the inner pipe further comprising a cross section that widens conically in the flow direction of the exhaust gas and the outer pipe.

3. The annular catalytic converter of claim 1, the outer pipe further comprising a cross section that narrows in the flow direction of the exhaust gas.

4. The annular catalytic converter of claim 1, wherein at least one of the inner pipe or the outer pipe has an oval or an elliptical cross section.

5. The annular catalytic converter of claim 1, wherein a size ratio of the annular catalytic converter is defined by the formula $\tan \left(2\right)=\frac{\sqrt{D{2}^2-D{1}^2+(D1+{\left(L*\tan \left(1\right)\right)}^2}-D2}{L}.$

6. The annular catalytic converter of claim 1, further comprising at least one matrix having a metallic honeycomb body arranged in the annular flow path, wherein the matrix has a cross-sectional profile that follows the cross-sectional profile of the annular flow path.

7. The annular catalytic converter of claim 6, the metallic honeycomb body further comprising: a multiplicity of metallic foils which are stacked one on top of the other and which are wound up to form the honeycomb body, at least a portion of the multiplicity of metallic foils are corrugated; wherein the conicity of the metallic honeycomb body and thus of the matrix along its flow direction are influenced through variation of the corrugation height and of the corrugation density between the gas inlet side and the gas outlet side of the matrix.

8. The annular catalytic converter of claim 6, wherein an optimized incident flow onto the at least one matrix arranged in the annular flow path is achieved by an inner wall of the diverting region in conjunction with a guide element on the inner pipe.

9. The annular catalytic converter of claim 1, the diverting region further comprising a cooling device.

10. The annular catalytic converter of claim 9, the cooling device further comprising a double-walled section, which is flowed through by a coolant, of the diverting region.

11. The annular catalytic converter of claim 1, the inner pipe further comprising: at least one guide element located at the gas outlet side of the tubular flow path and at the gas inlet side of the annular flow path; wherein the exhaust-gas flow flowing through the annular catalytic converter is diverted by the at least one guide element.

12. The annular catalytic converter of claim 11, the at least one guide element further comprising a bead-like bend of a free end of the inner pipe radially outward and into the annular flow path.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be discussed in more detail below on the basis of exemplary embodiments with reference to the drawings. In the drawings:

(2) FIG. 1 shows a schematic view of the inner pipe and of the outer pipe of an annular catalytic converter for the purposes of illustrating the different cross-sectional areas and angles;

(3) FIG. 2 shows a schematic sectional view through the annular catalytic converter, wherein the diverting region is of double-walled design and is flowed through by a coolant; and

(4) FIG. 3 shows a detail view of the diverting region and of the guide element formed on the inner pipe.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

(5) The following description of the preferred embodiment(s) is merely exemplary in nature and is in no way intended to limit the invention, its application, or uses.

(6) FIG. 1 shows a schematic view of the inner pipe 2, which is surrounded by the outer pipe 2. The two pipes 1 and 2 are oriented concentrically around the central axis 3. The cross-sectional area D1 is shown at the gas inlet side of the inner pipe 1, whereas the cross-sectional area D3 is illustrated at the gas outlet side of the inner pipe 1. The cross-sectional area D4 or the differential area A2 between the cross-sectional areas D3 and D4 is shown at the gas inlet side of the annular flow path which is formed between the inner pipe 1 and the outer pipe 2. The differential area A1 between the cross-sectional areas D1 and D2 is shown at the gas outlet side of the annular flow path.

(7) The inner pipe 1 widens from the gas inlet side to the gas outlet side by the angle 1 with respect to the central axis 3. The outer pipe widens from its gas outlet side to its gas inlet side by the angle 2 with respect to the central axis.

(8) The throughflow sequence is from the gas inlet side of the inner pipe 1 to the gas outlet side of the inner pipe 1, where, in the diverting region not shown in FIG. 1, the exhaust gas is diverted into the gas inlet side of the outer pipe 2 or of the annular flow path. From there, the exhaust gas flows to the gas outlet side of the annular flow path or of the outer pipe 2.

(9) The pipes 1, 2 have a length L which, in the exemplary embodiment in FIG. 1, is identical for both pipes 1, 2.

(10) A variation of the angles 1 and 2 leads to different geometries for the tubular flow path and the annular flow path. In an embodiment, the annular flow path may have a cross section that remains constant along the flow direction, or a varying cross section.

(11) FIG. 2 shows a view of the gas outlet side of the tubular flow path, and the diverting region 4 adjoining the gas outlet side. The diverting region 4 is formed by a pot-shaped wall 5, which serves as a baffle wall for the inflowing exhaust gas and which ultimately serves to divert the exhaust gas outward in a radial direction and ultimately into the annular flow path.

(12) As may be seen from the arrows in FIG. 2, the main flow direction in the tubular flow path is opposite to the main flow direction in the annular flow path.

(13) Also shown is a second wall 6, which follows the profile of the inner wall 5 and which thus forms a region 7 through which flow may pass, for example a channel or some other closed volume through which flow may pass. This may be flowed through by a coolant, and thermal energy is thus dissipated from the exhaust gas via the inner wall 5.

(14) The free end of the inner pipe 1 furthermore has a bead-like bend radially outward and into the annular flow path. This generates the guide element 10, which is intended to improve the exhaust-gas flow in the volume 9 enclosed by the diverting region 4. The guide element 10 is configured to be of fully encircling form in a radial direction.

(15) FIG. 3 shows a detail view of the diverting region 4 and the size ratios of the inner wall 5 and the guide element 10 in relation to the diameter D of the tubular flow path at its gas outlet. A diverting region 4 and a guide element 10 which have dimensions within the magnitudes specified in the table below generate the most homogeneous flow possible at the gas inlet of the annular flow path or of the catalytically active matrix 8.

(16) TABLE-US-00001 0.0153 R1/D 3.450 0.0153 R2/D 3.461 0.0076 R3/D 3.461 0.0076 R4/D 3.461 0.0153 R5/D 3.461 0.0153 R6/D 3.461 1.100 D7/D 3.461 0.0153 L1/D 3.384 0.0076 L2/D 3.384 0.0153 L3/D 3.384 0.0153 L4/D 3.438 0.0153 L5/D 3.438 0.0000 L6/D 3.469 0.0153 L7/D 3.4446 0.0153 L8/D 3.450 0.0153 L9/D 4.230 0.0460 L10/D 3.461 0.0460 L11/D 3.461 0.0460 L12/D 3.461 0.0153 L13/D 3.461 0.0153 L14/D 3.461 0.0153 L15/D 3.461

(17) Here, the free end of the inner pipe is bent outward and does not come back into contact with the outer side of the inner pipe. Here, the reference designations L1 to L15 each denote lengths of individual sections. The reference designations R1 to R6 denote different radii of the components. The reference designation D denotes the diameter of the inner pipe at its gas outlet side and the reference designation D7 denotes the diameter of the outer pipe at its gas inlet side.

(18) The different features of the individual exemplary embodiments may also be combined with one another. The exemplary embodiments in FIGS. 1 to 3 are not of a limiting nature and serve for illustrating the concept of the invention.

(19) The description of the invention is merely exemplary in nature and, thus, variations that do not depart from the gist of the invention are intended to be within the scope of the invention. Such variations are not to be regarded as a departure from the spirit and scope of the invention.