DE102015121580A1 - Double-walled exhaust manifold and exhaust manifold system - Google Patents

Abstract

The invention relates to a double-walled exhaust manifold part for an internal combustion engine, wherein an inner shell (4) and an outer shell (6) are formed of metal, wherein in the inner shell at least one interfering means (8) is provided to prevent self-resonance by exhaust pulsations. The invention also relates to an exhaust manifold system having such exhaust manifold parts.

Description

The invention relates to a double-walled exhaust manifold for an internal combustion engine, wherein an inner shell and an outer shell are formed from metal. The invention also relates to an exhaust manifold system having such exhaust manifold parts.

An exhaust manifold system with double-walled exhaust manifold parts is for example from DE 10 2014 103 804 A1 known. In this case, the double-walled exhaust manifold parts, also called LSI manifold parts, can each be formed from a sheet with a small wall thickness. The abbreviation "LSI" stands for "air gap isolated". As a result, a good insulation and associated low heat losses of the exhaust gas are ensured on the way to the catalyst. This in turn requires a rapid heating or achievement of the operating temperature of the catalyst at a cold engine start. In addition, due to low wall thicknesses exhaust manifold parts can be manufactured with low material costs. The supporting structure, ie the outer shell, remains cold and can therefore also be manufactured with significantly lower wall thicknesses.

The problem with such double-walled exhaust manifold parts, however, is that in the inner shell due to gas pulsations of the internal combustion engine, the exhaust gas flow in the region of the self-resonance of the inner shell can be excited, which can then lead to the destruction of the inner shell in the case of a high amplitude resonance. To address this problem, it is known to change the shape of the exhaust manifold so that the amplitude resonance curve is moved out of the critical range. This is achieved for example by material thickening of the inner shell. However, this again results in an increased cost of materials and contradicts the actual purpose of the LSI technique, since more energy is needed to heat the catalyst in a cold start again.

The object of the invention is therefore to provide a double-walled exhaust manifold or an exhaust manifold with at least one such exhaust manifold part, which solve the above problem in a simple and cost-effective manner.

This object is achieved in that at least one interfering means to prevent self-resonance is provided by exhaust pulsations in the inner shell. This makes it possible to prevent the occurrence of natural resonances and thus the structure of an amplitude resonance in principle. In a particularly advantageous manner, the interfering means is designed as a disturbing element penetrating at least the inner shell. As a result, the excitation of the amplitude resonance is effectively prevented with a relatively low cost of materials.

A particularly advantageous embodiment results from the fact that the Störorgan is designed as Zugankerorgan that penetrates the inner and outer shell and connects non-positively with each other. As a result, the Störorgan is thus additionally used as a connecting means of inner shell and outer shell. With regard to the penetration of inner and outer shell, the Störorgan can be welded sealed. It is then also particularly advantageous if the interfering element is rod-shaped or tubular.

In order to avoid obstruction of the exhaust gas flow, it is advantageous if the at least one interfering means is provided in relation to an exhaust gas flow in the inner shell in a dead water region of the exhaust gas flow.

Advantageously, the inner shell and the outer shell are formed from a sheet with a small wall thickness.

The invention is also solved by an exhaust manifold system having such a double-walled exhaust manifold.

The invention will be explained in more detail with reference to a drawing, in which case the single figure shows a perspective, partially sectioned view of a double-walled exhaust manifold part according to the invention.

The single FIGURE shows an inventive exhaust manifold 2 , which is part of a not shown exhaust manifold for an internal combustion engine. In order to lead exhaust gas from the internal combustion engine to a catalyst, not shown, is an inner shell 4 provided in a known manner according to the LSI technique of an outer shell 6 is surrounded. Both the inner shell 4 as well as the outer shell 6 are made of a sheet metal with a small wall thickness. This has for the inner shell 4 in particular the advantage that the heat losses of the exhaust gas on the way to the catalyst are extremely low and thus a rapid heating of the operating temperature of the catalyst after the engine cold start is ensured. A sufficient insulating effect is given due to the air gap. Due to the low heating of the outer shell 6 This can also be made with a small wall thickness, without the load capacity is limited.

Gas pulsations of the internal combustion engine can now the inner shell in the self-resonant range so that it can be destroyed due to the amplitude resonance. According to the invention it is now provided that a Störorgan as 8th executed Störmittel in a Totwasserbereich 10 behind a curvature in the inner shell 4 is provided. As a result, a self-resonance is effectively prevented. The sturgeon 8th is executed in the present embodiment as a tubular tie rod, which is the inner shell 4 and the outer shell 6 penetrates and connects non-positively. For this purpose and for sealing is the tie rod 8th both in the inner shell 4 as well as in the outer shell 6 shrink wrapped.

It should be clear that, depending on the design of the exhaust manifold system, several exhaust manifold parts according to the invention 2 can be provided. Also, the inventive design of the interfering means is not limited to a pipe or rod-shaped interfering organ. Other geometric shapes may also be provided to effectively prevent the build-up of self-resonance.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102014103804 A1 [0002]

Claims (7)

Double-walled exhaust manifold for an internal combustion engine, wherein an inner shell ( 4 ) and an outer shell ( 6 ) are formed of metal, characterized in that in the inner shell at least one interfering means ( 8th ) is provided to prevent self-resonance by exhaust gas pulsations. Double-walled exhaust manifold according to claim 1, characterized in that the interfering means ( 8th ) as an at least the inner shell ( 4 ) penetrating Störorgan is formed. Double-walled exhaust manifold according to claim 2, characterized in that the Störorgan ( 8th ) is formed as Zugankerorgan that the inner and outer shell ( 4 . 6 ) penetrates and frictionally connects with each other. Double-walled exhaust manifold according to claim 2 or 3, characterized in that the Störorgan ( 8th ) is rod-shaped or tubular. Double-walled exhaust manifold according to one of the preceding claims, characterized in that the interfering means ( 8th ) with respect to an exhaust gas flow in the inner shell ( 4 ) in a dead water area ( 10 ) of the exhaust gas flow is provided. Double-walled exhaust manifold according to one of the preceding claims, characterized in that the inner shell ( 4 ) and the outer shell ( 6 ) are formed from a sheet with a small wall thickness. Exhaust manifold system with at least one double-walled exhaust manifold ( 2 ) according to any one of the preceding claims.

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