Connection Element Arranged Between a Housing and an Exhaust Pipe

Abstract

A connecting element between a housing and an exhaust pipe, particularly a cone, is characterized in that the connecting element is provided at its interior with at least one guide surface capable of pulsing the exhaust gas flow into rotation.

Description

The invention relates to a connecting element between a housing and an exhaust pipe, particularly a cone.

In exhaust systems, particularly for motor vehicles, one such connecting element serves to adapt a large flow cross section, such as in the interior of a housing, to a smaller flow cross section such as in an exhaust pipe. Generally expressed, the connecting element acts like a funnel. The housing concerned may be, for instance, a silencer, a housing for a catalyst or a housing for a filter.

In modern exhaust systems it is necessary to inject a medium into the exhaust gas flow to produce certain reactions. For example, upstream of a Diesel particle filter, fuel may be injected so that the particles retained in the filter are subjected to controlled combustion. In an SCR system it may also be provided for that urea is injected to infuse ammonia as a means for reducing the nitrous oxides in the exhaust gas, it being generally a requirement that the injected medium is evenly distributed in the exhaust gas flow for a uniform effect.

Various attempts have been made to distribute the injected medium uniformly in the exhaust gas. For example, deflectors may be sited directly upstream or downstream of the location in the exhaust pipe at which the medium is injected so that the exhaust gas is swirled to ensure a good distribution of the injected medium. However, engineering deflectors in the interior of the exhaust pipe is a problem both as regards the complications in siting them and as regards strength considerations.

The object of the invention is to achieve a good distribution of the injected medium in the exhaust gas flow with minimum complication and high reliability.

For this purpose it is provided for in accordance with the invention that the connecting element is provided at its interior with at least one guide surface capable of pulsing the exhaust gas flow into rotation. The gist of the invention is to swirl the exhaust gas flow as soon as it leaves a housing sited upstream from the location at which the medium is injected, resulting in good swirling and thus a good distribution of the medium in the exhaust gas flow. The connecting element between the housing and the exhaust pipe is particularly suitable for this purpose since it is relatively expansive so that it is now much easier, than in a narrow exhaust pipe, to correspondingly engineer swirling the exhaust gas flow.

The guide surface with which the exhaust gas flow is pulsed into rotation may be provided at least one deflector attached to the connecting element or, preferably, by plastic deformation of the wall sections of the connecting element. This aspect is particularly of advantage since no additional components need to be attached in thus simplifying production, whilst eliminating the risk of components becoming detached from the connecting element and damaging other components of the exhaust system.

Preferably the guide surface is formed by at least one helicoidal path impressed in the wall of the connecting element. Plastic deformation of the wall of the swirler surface area in this way is achievable with few complications.

Advantageous aspects of the invention read from the sub-claims.

The invention will now be described by way of a preferred embodiment as shown in the attached sole drawing depicting diagrammatically a section through a housing, a connecting element and an attached exhaust pipe.

Shown in the sole FIGURE is a housing 10, in the interior of which a substrate 12 is arranged, the function of which is immaterial to understanding the invention. Instead of the substrate 12 the housing 10 could also enclose a silencer.

The housing 10 has a through flow of exhaust gas in the direction of the arrow P. Viewed in the direction of flow the housing 10 is connected downstream by a connecting element 14 having the main function of reducing the flow cross section for the exhaust gas from that of the housing 10 to that of a exhaust pipe 16 attached downstream to the connecting element 14.

In the exhaust pipe 16 downstream of the connecting element 14 is an injector 18 by means of which a medium such as fuel or urea can be injected into the interior of the exhaust pipe 16 and thus into the exhaust gas flow.

The connecting element 14 in the embodiment as shown is configured two-shelled, i.e. it comprising an outer shell 20 connected via two flanges 22, 24 to the exhaust pipe 16 and housing 10 respectively. Located within the outer shell 20 is an inner shell 26 shaped so that a helical pathway 28 is formed circumferentially. The helical pathway 28 comprises a helicoidal guide or swirler surface 30 which is oriented more or less radial to the main direction of flow of the exhaust gas. Since the swirler surface 30 is oriented at an angle to the main direction of flow of the exhaust gas it pulses the exhaust gas flow into rotation, resulting in a particularly good admixture of the medium injected by the injector 18 and the exhaust gas flow.

Since at least the inner shell 26 of the connecting element 14 is made of sheet metal, the swirler surface 30 can be simply shaped by plastic deformation of the inner shell 26, particularly by deep drawing. It will readily be appreciated that the flow response is set by suitably selecting the pitch of the helical pathway 28. Thus, instead of a single helical pathway a multiple helical pathway may be employed which with a correspondingly larger pitch presents itself in the form of a plurality of separate swirler surfaces 30 covering a circumferential range of less than 360°.

In an aspect different to that as shown, the connecting element may also be configured as a single-shell element, the wall of the connecting element being sufficiently rugged despite the impressed swirler surface areas. The fact that the swirler surface is visible to the outside in a single-shell connecting element is of no detriment to the wanted function.

LIST OF REFERENCE NUMERALS

• • 10 housing
  • 12 substrate
  • 14 connecting section
  • 16 exhaust pipe
  • 18 injector
  • 20 outer shell
  • 22 flange
  • 24 flange
  • 26 inner shell
  • 28 helical pathway
  • 30 swirler surface area

Claims

1.-8. (canceled)

9. A connecting element between a housing and an exhaust pipe, the connecting element having at its interior at least one guide surface formed by plastic deformed wall sections of the connecting element capable of pulsing the exhaust gas flow into rotation.

10. The connecting element of claim 9, wherein the guide surface, as viewed in the direction of exhaust gas flow, is oriented at an angle.

11. The connecting element of claim 10, wherein the guide surface is formed helicoidal.

12. The connecting element of claim 9, wherein the guide surface is formed by at least one helical pathway.

13. The connecting element of claim 12, wherein the guide surface is oriented radially.

14. The connecting element of claim 9, wherein the connecting element is configured multi-walled.

15. The connecting element of claim 9, wherein the connecting element is configured as a cone.