EXHAUST MANIFOLD OF AN INTERNAL COMBUSTION ENGINE

DESCRIPTION

The invention relates to an exhaust manifold of an internal combustion engine according to the precharacterizing clause of claim 1.

An exhaust manifold of this type is known from EP 1 426 557 A1.

A technical problem occurring in the case of exhaust manifolds of this type is thermal expansion which occurs both between the exhaust pipe bends themselves, but also between said pipe bends and a supply gas duct of the turbine housing of an exhaust-gas turbocharger connected to the exhaust manifold. This thermal expansion has to be compensated for in order to avoid damage. If the exhaust manifold is designed as a doubie- walied, air-gap-insulated (AGI) manifold, use is made as compensators therefor of interna! sliding fits which are not, however, gastight, since the pipe components forming the sliding fits are merely plugged one inside another, but are not welded in a gastight manner to one another. However, the leakages which occur as a result at the inner pipes of the AGI manifold smooth the exhaust pressure pulsations which are needed in the case of twin scroll applications for better utilization of power and therefore for increasing performance. Sliding fits at the connecting points result in the volume surrounding the pipe components and being formed by the outer, gastight casing being filled and emptied by the exhaust pressure pulsations.

The composition of the exhaust mixture in said outer volume changes, for example, with the degree of flushing of the cylinders with fresh air.

It is therefore the object of the present invention to provide an exhaust manifold of an internal combustion engine of the type specified in the preamble of claim 1 , making it possible, in particular if the manifold is designed as a single-walled sheet-metal manifold, to provide a structurally flexible, gastight configuration which can be produced cost effectively.

This object is achieved by the features of claim 1.

The following features in particular are included in the particular advantages of the solution according to the invention: gastight pipe connection; exhaust composition is not changed by mixing an additional 5 volume with gas. Better conditions for cylinder flushing as a result of increased valve overlapping; no efficiency losses as a result of internal leakage in the case of turbochargers with twin scroll applications; cost-neutral possibility of production in comparison to known i o sliding fit embodiments; no construction space losses for the outer shell which is required in the case of standard AGI manifolds, and therefore the solution according to the invention is virtually identical in terms of fit to single-wail manifolds; 15 - cost saving on account of omitting the outer shell; unrestricted use of the advantages of sheet-metal manifold embodiments in comparison to cast manifolds, such as, for example, short heating time of the catalytic converter and corresponding emission and power advantages.

20 Since it is customary in the case of sheet-metal manifolds according to current standards frequently to use pipes formed by interna! high pressure (IHP pipes), it is advantageously possible, by means of the integrated design of the compensator, to form the latter neutrally in terms of costs during the forming by internal high pressure.

25 The dependent claims contain advantageous developments of the invention. in this connection, in particular the provision of a supporting sleeve should be mentioned, said supporting sleeve being placed loosely into the region of the compensator before the welding of the pipe components and

30 preventing sagging transversely with respect to the axial direction of compensation by absorbing the bending forces which occur.

in a particularly preferred embodiment, it is possible to fix the supporting sleeve on one side, for which purpose, for example, welding is possible.

Furthermore, a turbine housing according to the invention, which constitutes a subject which can be treated independently, is defined in claims 15 and 16.

Further details, advantages and features of the present invention emerge from the description below of exemplary embodiments with reference to the drawing, in which: Figure 1 shows a perspective illustration of the essential parts of an AGI exhaust manifold with a turbine housing of an exhaust-gas turbocharger (prior art);

Figure 2 shows a perspective illustration of an exhaust manifold according to the invention; Figure s shows a sectional iilustration through a pipe connection between the exhaust manifold and a connecting pipe to the turbine housing in order to clearly show the compensator according to the invention which is integrated into the pipe connection;

Figure 4 shows a sectional illustration through a pipe connection between two exhaust pipe bends with the use of a second material layer.

Figure 1 shows a perspective view of an exhaust manifold 18 which is flange-mounted on an interna! combustion engine 20 (indicated by a chain-dotted line) and is connected to a turbine housing 17 of an exhaust- gas turbocharger (not illustrated in its entirety). The illustration of said parts suffices for the explanations below of the principles of the present invention, wherein it should be emphasized that the exhaust-gas turbocharger of course has all of the other customary design features, but which are not reproduced in figure 1 so as to simplify the illustration. According to the embodiment iliustrated in figure 1, the interna! combustion engine 20 has five exhaust pipe bends 1 which lead to associated T exhaust pipes 3 and are connected thereto, and open into a

collector component 4 which is likewise designed as a T exhaust pipe, as revealed in detail in the graphical illustration of figure 1.

As explained, figure 1 merely shows an exemplary embodiment of an exhaust manifold, and therefore it is self-evident to a person skilled in the art that other types of exhaust manifold, in particular matched to the particular internal combustion engine, are also possible.

The exhaust manifoid 18 illustrated in figure 1 corresponds to that of EP 1 426 557 A1 belonging to the applicant of the present application, and therefore the content of EP 1 426 557 A1 is hereby incorporated in its entirety, by reference to this application, in the content of disclosure of the present application, since a compensator according to the invention, to be described below, can also be used in the case of this exhaust manifold.

Figure 1 shows in particular that the exhaust manifold 18 is connected to the collector component 4 via a supply gas duct 21. The supply gas duct 21 is connected in terms of flow to a rotor space 15 of the turbine housing 7, with the rotor space 15 accommodating the turbine rotor

(not illustrated specifically in figure 1 ).

Figure 2 shows the single-walled exhaust manifold according to the invention with pipe bends 1 together with compensators 19' and the turbine housing 17.

The use of the at least one compensator 19' in at least one pipe bend 1 is provided in this case. After all of the pipe bends 1 have been brought together, the arrangement of an additional compensator 19" in a connecting conduit 27 to the turbine housing 17 is possible, but not necessary. in order to compensate for the thermal expansions, the exhaust manifoid according to the invention has a compensator 19' which is illustrated in detail in the sectional illustration of figure 3.

For this purpose, figure 3 shows a pipe portion 4' of the pipe component 4 together with the compensator 19' which is designed as an integral component of said pipe component 4'.

As the sectional illustration of figure 3 shows, the compensator 19' is designed as a compensator bellows 22 which, in the case of the example,

comprises four bellows parts 22a-22d. it goes without saying that the number of bellows parts can be varied depending on the application in order to be able to correspondingly compensate for thermal expansions which differ under some circumstances from case to case. As emerges from figure 3, the compensator 19' is an axial compensator which, in the case of the example, compensates for distortions between the pipe portion 4' and the supply gas duct 21. it should be mentioned that, in terms of principle, such a compensator 19' can likewise be used between the other pipe connection portions of the exhaust manifold 18. The particular advantage of the integrated design of the compensator 19' is that it is now possible, according to the embodiment illustrated in figure 3, to weid the pipe portion 4' and the supply gas duct 21 to each other in a gastight manner, for which purpose a welded pipe joint 25 is provided. in order, furthermore, to prevent sagging transversely with respect to the axial extent of the arrangement illustrated in figure 3, said particularly preferred embodiment furthermore has a supporting sieeve 23 which, as shown in figure 3, is arranged within the pipe connection in the region of the compensator 19'. Said supporting sleeve can be placed loosely into the arrangement during the course of the assembly and, if the need arises, can be fixed, for example at the welding point 24, to the pipe portion 4', with an inner sliding fit being produced at the point marked by the reference number 26.

Although, in the case of the particularly preferred embodiment illustrated in figure 3, a compensator bellows is illustrated as the compensator structure, other compensator structures are in principle also conceivable if they permit a gastight connection between the pipe components which are connected to one another.

Although, according to the particularly preferred embodiment of figure 3, the compensator 19' is an integral component of the pipe portion 4', it is also conceivable in principle to design the compensator 19' as an integral component of the supply gas duct 21.

It is also possible in principle to design the compensator 19' as a separate component which is an integral part of an intermediate pipe component which is then connected in a gastight manner at one of its ends to the exhaust manifold 18, such as, for example, the pipe portion 4", and at the other end to the supply gas duct 21 of the turbine housing 17.

Figure 4 shows, in the form of a sectional image, the use of a plurality of material layers in the region of the compensator 19'. During the formation of the expansion bellows geometry in the high pressure forming operation, further material layers (such as, for example, a second material layer 28), which were placed loosely onto the inner pipe, are connected fixedly to one another by the forming operation and can therefore absorb increased forces. in addition to the above written disclosure of the invention, reference is hereby explicitly made to the graphical illustration thereof in the figures.

List of reference numbers

1 Exhaust pipe bend

2 Input flange 3 T exhaust pipe

4 Collector component 4' Pipe portion

5 Bypass duct

6 Left spiral half 7 Right spiral half

8 Outlet duct

9 Outlet flange

10 Throttle plate

11 Throttle lever 12 Outlet sheet

13 Terminating sheet

14 Bearing housing flange

15 Rotor space

16 Lower cover 17 Turbine housing

18 Exhaust manifold

19 Welded seam between 6 and 7 19' Compensator

20 Internal combustion engine 21 Supply gas duct

22 Compensator bellows

22a-22d Expansion bellows portions

23 Supporting sleeve

24 Welding point 25 Pipe weid

26 Inner sliding fit

27 Connecting conduit

28 Second material layer