GB2498087A

GB2498087A - Exhaust gas guide element

Info

Publication number: GB2498087A
Application number: GB201223143A
Authority: GB
Inventors: Vijaya Rajagopal; Harshavardhan Srinivasaiah
Original assignee: Daimler AG
Current assignee: Mercedes Benz Group AG
Priority date: 2012-12-20
Filing date: 2012-12-20
Publication date: 2013-07-03
Also published as: GB201223143D0

Abstract

An exhaust gas guide element 16, for an exhaust gas system of a combustion engine, comprises a first exhaust pipe 18 which has a first length portion 22 through which exhaust gas of the combustion engine flows. The exhaust gas guide element also comprises a second exhaust pipe 20 which has a second length portion 24 which extends at an angle or perpendicularly to the first length portion, and through which exhaust gas flows. The second length portion is fluidically connected with the first exhaust pipe. The second exhaust pipe has a third length portion 26 which is fluidically connected to the second length portion, and extends parallel to the first length portion. The third length portion is received within the first length portion, and has a through opening 28 for the exhaust gas. The third length portion may be off0centre relative to the first length portion. The first and third length portions may have different cross-sectional shapes. The exhaust gas guide element is used to divide an exhaust gas flow into two separate flows.

Description

Exhaust Gas Guide Element for an Exhaust Gas System of a Combustion Engine The invention relates to an exhaust gas guide element for an exhaust gas system of a combustion engine according to the preamble of claim 1 Such exhaust gas guide elements for exhaust gas systems of combustion engines are well known for instance from the series production of motor vehicles. The exhaust gas guide element serves for guiding exhaust gas of the combustion engine and comprises a first exhaust pipe, which has a first length portion, through which exhaust gas can flow.

The exhaust gas guide element further comprises a second exhaust pipe, which has a second length portion, which extends at an angle or perpendicularly to the first length portion and through which exhaust gas can flow. The second length portion in this connection is fluidically connected to the first exhaust pipe.

It may be envisaged that the second length portion is fluidically connected to the first length portion. As a consequence of the fluidic connection exhaust gas flowing through the first exhaust pipe, in particular through the first length portion, can be branched off from the first exhaust pipe and supplied to the second length portion so that the exhaust gas flows both through the first and through the second exhaust pipes. In other words, the exhaust guide element divides into the two length portions extending at an angle or perpendicularly to each other in order to for instance guide the exhaust gas to corresponding spots of the exhaust system or to lead the exhaust gas from corresponding spots from the combustion machine away.

It has turned out that the common fluidic connection of the second length portion with the first length portion leads to a raised construction space requirement of the exhaust gas guide element and to an only insufficient distribution of the exhaust gas to the first exhaust pipe and the second exhaust pipe.

It therefore is the task of the present invention to further develop an exhaust gas guide I; element in such a way that the exhaust gas can be distributed across the exhaust pipes in a particularly construction space efficient way.

This task is solved by an exhaust gas guide element having the features of claim 1.

Advantageous embodiments with expedient and non-trivial further developments are indicated in the remaining claims.

In order to provide an exhaust gas guide element for an exhaust system of a combustion engine, in particular of a motor vehicle, according to the preamble of patent claim 1 in which exhaust gas guide element a particularly good distribution across the exhaust pipes can be realized in a particularly construction space efficient way, it is envisaged according to the present invention that the second exhaust pipe has a third length portion, which is fluidically connected with the second length portion and extends essentially in parallel to the first length portion, the third length portion being contained within the first length portion and having a flow through opening for the exhaust gas.

Preferably, the third length portion is arranged in the flow direction of the exhaust gas through the second exhaust pipe upstream of the second length portion, wherein the flow through opening is an inlet opening for the exhaust gas. In this way the exhaust gas can flow from the first exhaust pipe via the inlet opening into the second exhaust pipe and, to start with, into the third length portion, and can flow over from the third length portion into the second length portion. This realizes a particularly construction space efficient and simple and cost-efficient branching-off of the exhaust gas flowing through the first exhaust pipe to the second exhaust pipe, wherein the exhaust gas can be divided, i.e. distributed particularly well across the individual exhaust pipes.

In the exhaust gas guide element thus a pipe-in-pipe concept is devised, in which the second exhaust pipe at least partially, namely at least the third length portion of the second exhaust pipe, is contained within the first exhaust pipe, namely the first length portion of the first exhaust pipe. The branching-off of exhaust gas from the first exhaust pipe into the second exhaust pipe also allows for realizing a very good visual impression of the exhaust gas guide element.

Respective cross-sections of the exhaust pipes, in particular of the length portions, through which cross-sections corresponding exhaust gas can flow, in particular with regard to their respective shape may be correspondingly designed and for instance may differ in their design. As particularly advantageous it turned out to be, if respective cross-sections of the respective length portions, in particular of the first tength portion and the third length portion, through which cross-sections exhaust gas can flow, are adapted to an exhaust gas counter pressure prevailing in the respective associated exhaust pipe. In this way the distribution of the exhaust gas across the individual exhaust pipes can be adjusted particularly well. Thereby, it is for instance possible that an at least essentially equal quantity, i.e. by the at least essentially equal through flow volume andlor mass flow rate of the exhaust gas, flows through the exhaust pipes.

Further advantages, features, and details of the invention derive from the following description of preferred embodiments as well as from the drawing. The features and feature combinations previously mentioned in the description and the features and feature combinations mentioned in the following description of the figures andlor shown in the figures alone can be used not only in the respective indicated combination, but also in any other combination or taken atone, without leaving the scope of the present invention.

The drawing shows in: Fig. I part of a schematic perspective view of a combustion engine for a motor vehicle, comprising an exhaust gas system, which has an exhaust gas guide element with a first exhaust pipe, a second exhaust pipe, wherein the exhaust pipes have two length portions, which extend perpendicularly to each other and through which exhaust gas can flow, the two length portions being fluidically interconnected in such a way that one of the exhaust pipes is partially contained within the other exhaust pipe; Fig. 2 a schematic and perspective view of the exhaust gas guide element; Fig. 3 part of a schematic cross-sectional view of the exhaust gas guide element; Fig. 4 part of a further schematic cross-sectional view of the exhaust gas guide element according to a second embodiment; Fig. 5 a schematic and perspective view of the exhaust gas guide element according to a third embodiment, wherein one of the exhaust pipes is represented in a way to be transparent; and Fig. B part of a further schematic and perspective cross-sectional view of the exhaust gas guide element according to a fourth embodiment.

Fig-1 in a schematic perspective view shows a combustion engine 10 for a motor vehicle, for instance a utility vehicle. The combustion engine 10 has an exhaust gas system referred to as a whole as 12, which serves for discharging exhaust gas produced in combustion chambers of the combustion engine 10 from the combustion engine 10.

For this purpose the exhaust gas system 12 comprises an exhaust pipe system 14 with an exhaust gas guide element 16 shown also in Figs. 3 and 4. As can be seen particularly well from Fig. 2, the exhaust gas guide element 16 comprises a first exhaust pipe 16 and a second exhaust pipe 20. The first exhaust pipe 18 has a first length portion 22, through which exhaust gas of the combustion engine 10 can flow, with an at least essentially circular cross-section. The second exhaust pipe 20 has a second length portion 24 with an at least essentially circular crass-section, with the second length portion 24 extending at least essentially perpendiculthly to the first length portion 22. In this setup exhaust gas from the combustion engine 10 can flow also through the second length portion 24. For this purpose the second length portion 24 is fluidically connected with the first exhaust pipe 18 in a way that is still to be explained so that exhaust gas flowing through the first exhaust pipe 18 can be branched off tram the first exhaust pipe 18 and be fed into the second length portion 24.

In order to branch off exhaust gas the first exhaust pipe 18 and supply it to the second length portion 24, the second exhaust pipe 20 has a third length portion 26! which can be discerned from Fig. 3 and through which exhaust gas can flow and which is fluidically connected with the second length portion 24. In this connection the third length portion 26 is contained within the first length portion 22 and extends at least essentially in parallel to the first length portion 22. Further, the third length portion 26 has a flow through opening 28 for the exhaust gas. Further, the third length portion 26 in the flow direction of the exhaust gas is arranged upstream of the second length portion 24 and via an at least essentially arch-like, i.e. curved transition area, fluidically connected with the second ength portion 24.

The exhaust gas released from the combustion chambers of the combustion engine 10 initially flows into the first length portion 22 and passes through part of the first length portion 22. Subsequently, part of the exhaust gas flowing through the first length portion 22 can enter via the flow through opening 28, which is an inlet opening, into the third length portion 26 and thus into the second exhaust pipe 20. As the third length portion 26 is spaced apart from the first length portion 22 in the radial direction, the first exhaust pipe 18 in the area of the third length portion 26 has an at least essentially circular cross-section 30, through which another part of the exhaust gas can flow. This means that the one part of the exhaust gas is branched off into the second exhaust pipe 20, whilst the other part of the exhaust gas flows further through the first exhaust pipe 18. Thereby, the other part of the exhaust gas can flow over from the first length portion 22 into an adjacent fourth length portion 32 of the first exhaust pipe 18, wherein the fourth length portion 32 is fluidically connected with the first length portion 22 and extends at an angle relative to the first length portion 22.

By this branching-off a particularly advantageous distribution of the exhaust gas streams across the exhaust pipes 18, 20 can be realized in a construction space efficient way. The exhaust pipes 18, 20 are for instance made from a metallic material and welded together.

Further, the spot at which the third length portion 26 is contained within the first length portion 22 can be varied. Moreover, a variation of the geometry of the respective cross-sections, through which exhaust gas can flow, is possible.

As can be seen from Fig. 3, the third length portion 26 is contained at least essentially coaxially within the first length portion 22 so that a uniform gap in the circumferential direction of the third length portion 26 is produced between the third length portion 26 and the first length portion 22.

As can be seen from Fig. 4, also an off-centre arrangement of the third length portion 26 relative to the first length portion 22 is possible.

From Fig. 5 it can be gathered that the first length portion 22 at least in a partial area 34 of its longitudinal extension, within which first length portion 22 the third length portion 26 is contained, is widened in comparison with further partial areas adjacent to partial area 34 of the first length portion 22. Moreover, the third length portion 26 has a shape that differs from a circular shape.

Fig. B illustrates a further possibility of an off-centre arrangement of the third length portion 26 relative to the first length portion 22.

The arrangement of the third length portion 26 relative to the first length portion 22 as well as the respective shape of the corresponding cross-sections of the exhaust pipes 18, 20, and in particular of the length portions 22, 26, through which cross-sections exhaust gas can flow, are preferably adapted to an exhaust gas counter pressure prevailing in the respective associated exhaust pipe 18, 20. In this way for instance an at east essentially even distribution of the exhaust gas across the exhaust pipes 18, 20 can be realized.

In the exhaust gas guide element 16 thus a pipe-in-pipe concept is devised, in which the exhaust gas guide element 16 and correspondingly the exhaust gas stream divides between the length portions 22, 24, wherein in this branching a very good distribution of the exhaust gas can be achieved. Moreover, the exhaust gas guide element 16 conveys a very good visual impression and allows for the representation of a particularly good acoustic behaviour of the exhaust gas system 12.