WO1999067513A1

WO1999067513A1 - Improved catalyser housing

Info

Publication number: WO1999067513A1
Application number: PCT/NL1999/000368
Authority: WO
Inventors: Hermanus Gerhardus Grobbenhaar
Original assignee: Grand Prix Silencers B.V.
Priority date: 1998-06-23
Filing date: 1999-06-14
Publication date: 1999-12-29
Also published as: NL1009468C2; EP1090214A1; AU4294899A

Abstract

The invention relates to a catalytic converter unit received between a first and a second exhaust section of an exhaust of an internal combustion engine, comprising: a catalytic converter housing; a catalytic converter element arranged in the catalytic converter housing; a first connecting piece arranged between the first exhaust section and the catalytic converter housing; and a second connecting piece arranged between the second exhaust section and the catalytic converter housing, wherein at least the first exhaust section comprises at least two channels which are separated by a first separating element, and wherein the catalytic converter element is divided in longitudinal direction into a number of parts corresponding with the number of channels, which parts are separated by at least a second separating element aligned relative to the first separating element. These measures enable separated supply to the catalytic converter, also in the case of exhaust systems with separate channels for the supply of exhaust gases from different cylinders or different groups of cylinders. The use of such a separating element prevents destruction of the catalytic converter element in the case of possible temperature stresses. The partitions used with such separated channels could after all crush such a ceramic catalytic converter element.

Description

IMPROVED CATALYSER HOUSING

The present invention relates to a catalytic converter unit received between a first and a second exhaust section of an exhaust of an internal combustion engine, comprising a catalytic converter housing, a catalytic converter element arranged in the catalytic converter housing; a first connecting piece arranged between the first exhaust section and the catalytic converter housing; and a second connecting piece arranged between the second exhaust section and the catalytic converter housing. Such catalytic converter units are generally known. At present use is usually made of a metal as substrate for catalytic converter units, on which metal the catalytic materials are arranged. The substrate is provided with channels extending in longitudinal direction, on the inside of which said materials are arranged .

When attempting to increase the effectiveness of such catalytic converter units it is important that the temperatures of the combustion gases are as high as possible,- it is therefore important that the catalytic converter units are placed as close as possible to the engine. It is also important that the substrate can withstand high temperatures. Use is made for this purpose of a ceramic element. However, the ceramic material has the property that it is difficult to manufacture in di ensionally stable manner and that the material is brittle, breaks easily and has a different thermal coefficient of expansion than the metals commonly used in this art. The object of the present invention is therefore to provide such a catalytic converter unit, the construction of which is suitable for the use of catalytic converter substrates of ceramic material . This objective is achieved in that at least the first exhaust section comprises at least two channels which are separated by a first separating element, that the catalytic converter element is divided in the longitudinal direction into a number of parts corresponding with the number of channels, which parts are separated by at least a second separating element aligned relative to the first separating element.

These measures enable separated supply to the catalytic converter, also in the case of exhaust systems with separate channels for the supply of exhaust gases from different cylinders or different groups of cylinders. The use of such a separating element prevents destruction of the catalytic converter element in the case of possible temperature stresses. The partitions used with such separated channels could after all crush such a ceramic catalytic converter element.

Although, as stated above, the invention is mainly applicable in ceramic substrates of catalytic converters, it is not limited thereto; it is likewise applicable in other types of catalytic converter, for instance metal, or in the future perhaps plastic substrates .

As stated in claims 2 and 3 , this measure is possible in diverse configurations. The use of a gap between the first separating element and the second separating element results in improved protection of the catalytic converter in the case of possible temperature expansion. This advantage is enhanced further when the catalytic converter element is divided in transverse direction into at least two sections which are separated by an interspace and the first separating element connects onto the second separating element. The feature that the catalytic converter element and the catalytic converter housing are separated by a spacer element extending around the catalytic converter unit also provides protection for the catalytic converter unit if it should extend in radial direction. As stated, it is important that the catalytic converter unit be placed as close as possible to the engine in respect of the then higher temperature of the exhaust gases . When the engine is started the catalytic converter then becomes effective sooner. In respect of engine vibration it is important that rotation between the axis of the catalytic converter housing and the axis of at least the first exhaust section is possible on an axis extending transversely of one of these axes due to the connection between the first conical connecting piece and the catalytic converter housing, wherein the conical connecting piece connected sealingly to the outside of the catalytic converter housing and wherein a gap is formed between the edge of the catalytic converter housing and the conical connecting piece.

According to a particular embodiment hereof a shoulder is formed on the outside of the catalytic converter housing, wherein a sealing ring is arranged against the outside of the shoulder, and the first conical connecting piece rests against the sealing ring. This is structurally a particularly attractive embodiment. Said gap not only enables a rotation but also enables mutual axial displacement of the of the elements without destroying the catalytic converter housing.

According to another preferred embodiment the first or the second separating element is provided on its edges at the side of the other separating element with a thickened portion which mutually separates the channels in a position of the catalytic converter housing relative to the exhaust section which varies from the normal position.

It will be apparent that this provides for situations in which rotation of the diverse components results and wherein the channels are nevertheless mutually separated. The embodiment wherein the catalytic converter housing is seam-folded at its ends around the spacer element also results in an attractive, robust construction. The present invention will be elucidated hereinbelow with reference to the annexed drawings, in which: figure 1 shows a cross-sectional view in lengthwise direction of a first embodiment of the inven ion; figure 2 shows a cross-sectional view along the line II-II of figure 1; figure 3 is a longitudinal section of a second embodiment of the invention; figure 4 shows a detail view of the embodiment shown in figure 3 in a different position; figure 5 is a longitudinal section of a third embodiment of the present invention; figure 6 shows a view corresponding with figure 5 of a fourth embodiment of the present invention; figure 7 shows a longitudinal section of a fifth embodiment of the present invention,- and figure 8 is a longitudinal section of a sixth embodiment of the present invention. Shown in figure 1 is a catalytic converter unit designated in its entirety with 1 and placed between a first exhaust section 2 and a second exhaust section 3. The catalytic converter unit is formed by a substrate 4, manufactured from for instance a ceramic material, in which are formed channels extending in longitudinal direction which are not shown in the drawing.

The substrate is divided into a first section 5 and a second section 6 which are separated by a separating element in the form of a plate 7. A catalytic converter housing 8 in the form of a sleeve is arranged around catalytic converter substrate 4.

Because catalytic converter housing 8 has a larger diameter than exhaust sections 2,3, a first, in this case conical, connecting piece 9 is arranged between first exhaust section 2 and catalytic converter housing 8 and a second conical connecting piece 10 is arranged between second exhaust section 3 and catalytic converter housing 8. In the present case the conical connecting pieces are formed by conically deformed parts of the exhaust sections; it is possible to use other constructions for this purpose. Connection between catalytic converter housing 8 and both conical connecting pieces 9,10 takes place by means of a weld connection, as shown in the present figure, but it is also possible to make use of other types of connection, for instance a folded seam connection.

Arranged in first exhaust section 2 is a partition 11 whereby first exhaust section 2 is divided into two channels 12, 13. Supplied to these channels are flows originating from the cylinders, the ignition times of which are far removed from each other so as to prevent feedback of the gas flows . Separating plate 7 is arranged in the catalytic converter in order to also maintain this separation of the gas flows in the catalytic converter. It is of course quite possible to have partition 11 continue as far as the actual catalytic converter substrate 4, although this has the drawback that the ceramic catalytic converter substrate could quickly be destroyed in the case of possible mutual movement .

In some cases it is also important to maintain such a separation of gas flows after they have passed through the catalytic converter. For this purpose the separating plate 7 is extended on the side of the second exhaust section, to which it connects in a partition 14 arranged therein. This is however not important in all cases .

Figure 3 shows an embodiment wherein a mutual movement of the catalytic converter housing relative to both exhaust sections 2,3 is possible. For this purpose a shoulder 15 is formed on both sides of housing 8 in the form of a folded seam, wherein a sealing ring 16 is arranged on the outer side of each of the shoulders. At the location of this shoulder 15 and this sealing ring 16 the first conical connecting piece 9 has a convex shape so that a good seal is obtained in diverse angular positions of first connecting piece 2 relative to catalytic converter unit 1. It is pointed out here that it is not necessary for the housing to extend as far as the convex conical part of first connecting piece 9; a gap 17 is left here. A similar construction is arranged on the other side of the catalytic converter unit.

In order to also ensure the separation between the gas flows as the angular position changes, the end of partition 11 is in this case provided with a thickened portion 18. As shown in figure 4, this thickened portion results in a good separation of the gas flows. This thickened portion can be formed by for instance a folded seam or an element fixed thereto in a different manner. Figure 5 shows a third embodiment wherein, in order to compensate longitudinal expansion problems of the substrate of the catalytic converter, the substrate is divided in transverse direction into two sections so that, together with the other division, the catalytic converter is divided into four sections. Both sections are separated in longitudinal direction by an interspace 19. This space is available for absorbing expansion in longitudinal direction.

The substrate is further divided into two short sections by the division in transverse direction. This facilitates application by means of vapour deposition of the materials performing the catalytic function.

The embodiment of figure 6 also provides a somewhat resilient suspension of the sections of the catalytic converter substrate, in that the latter is received integrally in a spacer 20 taking for instance the form of a mat which is wrapped round the components of the catalytic converter. This mat is placed first in housing 8, whereafter the ends of the housing are seam- folded around spacer 20. This construction otherwise corresponds with the third embodiment. It is possible and attractive to manufacture the mat from a ceramic web; it is however also possible to apply other materials such as glass fibre. A spacer 20 can also be applied in an embodiment wherein a mutual rotation is not taken into account. This is shown in figure 7.

In this embodiment the catalytic converter substrate is divided into only two sections which as in the first and second embodiment are separated by a separating plate 7 around which is wrapped a spacer 20. The thus created unit is placed in housing 8.

Finally, figure 8 shows an embodiment which corresponds with the third embodiment shown in figure 5, but wherein use is made of exhaust pipes with a double C- configuration, such as can for instance be applied in engines with five cylinders or a multiple thereof. Use is made herein of an internal channel and two C-shaped external channels. The separation between the external channels mutually and between the external channels and the internal channel is formed by a separating element 21. A corresponding separating element 22 is arranged in the catalytic converter substrate. Here also a thickened portion 23 is arranged, the function of which corresponds with that of thickened portion 18 in figure 5. In respect of the different shape of the separating element, the thickened portion is herein embodied in the form of a ring.

It will be apparent that, subject to the number of cylinders, any geometry can be applied.

It will be apparent that the diverse embodiments can be mutually combined.

In the embodiments according to figures 3, 4, 5, 6 and 8 the end surfaces of the catalytic converter elements have in each case a convex shape. This convex shape has the result that the channels in the middle of the catalytic converter - as seen in cross-section - are longer than at the periphery. The channels hereby have a greater gas flow resistance in the middle than along the edge .

This effect forms at least a partial compensation for the fact that the density of the gas flow in the middle of the pipes is greater than at the edges. There thus results a more uniform distribution of the gas flow over the cross-section of the catalytic converter element .

It is otherwise possible to give the end surfaces a concave form. A reverse effect is then obtained. This can also be used to adapt the distribution of the gas flow.

With a combination of a concave and convex end wall the path length is balanced out again, so that the influence is neutral. The effects of the end surfaces can thus be used to influence the density of the gas flow.

Claims

1. Catalytic converter unit received between a first and a second exhaust section of an exhaust of an internal combustion engine, comprising:

- a catalytic converter housing;

- a catalytic converter element arranged in the catalytic converter housing; - a first connecting piece arranged between the first exhaust section and the catalytic converter housing; and

- a second connecting piece arranged between the second exhaust section and the catalytic converter housing, characterized in that at least the first exhaust section comprises at least two channels which are separated by a first separating element, the catalytic converter element is divided in longitudinal direction into a number of parts corresponding with the number of channels, which parts are separated by at least a second separating element aligned relative to the first separating element.

2. Catalytic converter unit as claimed in claim

1, characterized in that the first exhaust section comprises two channels of substantially equal cross- section, that the first separating element comprises a partition and that the second separating element comprises a plate separating two substantially identical parts of the catalytic converter element .

3. Catalytic converter unit as claimed in claim 1, characterized in that the first exhaust section comprises an internal channel and two external channels of substantially C-shaped cross-section, wherein the cross-section of the C-shaped channels substantially equals double the cross-section of the internal channel, that the second separating element has a corresponding cross-section and that the catalytic converter is divided into corresponding parts.

4. Catalytic converter unit as claimed in claim 1, 2 or 3 , characterized in that a narrow gap is situated between the first separating element and the second separating element .

5. Catalytic converter unit as claimed in claim 1, 2 or 3, characterized in that the catalytic converter element is divided in transverse direction into at least two sections separated by an interspace and that the first separating element connects onto the second separating element .

6. Catalytic converter unit as claimed in any of the foregoing claims, characterized in that the catalytic converter element and the catalytic converter housing are separated by a spacer element extending around the catalytic converter unit.

7. Catalytic converter unit as claimed in claim 6, characterized in that the spacer element comprises a mat.

8. Catalytic converter unit as claimed in any of the foregoing claims, characterized in that rotation between the axis of the catalytic converter housing and the axis of at least the first exhaust section is possible on an axis extending transversely of one of these axes due to the connection between the first conical connecting piece and the catalytic converter housing, wherein the conical connecting piece on the outside of the catalytic converter housing is connected sealingly to the outside of the catalytic converter housing and wherein a gap is formed between the edge of the catalytic converter housing and the conical connecting piece.

9. Catalytic converter unit as claimed in claim 8, characterized in that a shoulder is formed on the outside of the catalytic converter housing, a sealing ring is arranged against the outside of the shoulder, wherein the first conical connecting piece rests against the sealing ring.

10. Catalytic converter unit as claimed in claim 8 or 9 , characterized in that the first or the second separating element is provided on its edges at the side of the other separating element with a thickened portion which mutually separates the channels in a position of the catalytic converter housing relative to the exhaust section which varies from the normal position.

11. Catalytic converter unit as claimed in claim 10, characterized in that the catalytic converter housing is seam-folded at its ends around the spacer element .