Power plants – Internal combustion engine with treatment or handling of... – Methods
Patent
1989-05-11
1990-05-22
Hart, Douglas
Power plants
Internal combustion engine with treatment or handling of...
Methods
60299, 60313, 60276, F01N 328
Patent
active
049266349
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method for producing a homogeneous exhaust gas mixture in an exhaust system in accordance with the introductory part of claim 1 and to apparatus for the practice of the method.
To be able to conform to the emissions standards with regard to the composition of exhaust gases, it is necessary to regulate the composition of the fuel-air mixture such that, insofar as possible, a stoichiometric mixture will be present in all ranges of operation. This is attempted by so-called lambda control, in which the oxygen content in the exhaust is measured with a lambda probe. In internal combustion engines having two banks of cylinders, especially so-called V-engines, it is necessary for reasons of space, among other things, to provide two catalysts, each taking half of the total exhaust stream. To avoid the cost of two lambda probes and the corresponding controls, in a known exhaust system (MTZ 46 (1985) P. 305) a cross connection is provided between the exhaust pipes which runs each from one cylinder bank to a catalyst. The lambda probe is disposed in this cross connection. The cross connection is said to achieve a sufficient mixing of the exhaust streams from the two cylinder banks and to assure correct control by the lambda probe. It has been found in practice, however, that with a cross connection of this kind a homogeneous exhaust mixture cannot be produced, though it is essential for complete detoxification in the two catalysts.
It is the purpose of the invention to create a method which will assure that the exhaust fed to the two catalysts will have a largely identical composition, without the need for any measures which would undesirably increase the back pressure in the exhaust system.
This purpose is accomplished in accordance with the invention by the features specified in the specific part of claim 1.
In the proposal according to the invention, dividing the exhaust stream from each cylinder bank into two parts and bringing a portion of the one exhaust stream together with a portion of the other exhaust stream brings it about that exhaust streams of identical composition and also of identical volume are carried to the two catalysts. The lambda probe can then be disposed in one of the two pipes leading to the catalysts.
Apparatus for the practice of the method are described in the subordinate claims.
A number of embodiments of the invention are described below in conjunction with the drawings, wherein:
FIG. 1 is a diagrammatic representation of an exhaust system for a V-6 internal combustion engine in a first embodiment,
FIG. 2 is a diagrammatic representation of an exhaust system for a V-6 internal combustion engine in a second embodiment,
FIG. 3 is a section taken along line 3--3 in FIG. 2,
FIG. 4 is a section taken along line 4--4 in FIG. 2,
FIG. 5 is a diagrammatic cross section taken through an additional embodiment of a mixing chamber,
FIG. 6 is a section taken along line 6--6 in FIG. 5,
FIG. 7 is a section taken along line 7--7 in FIG. 5,
FIG. 8 is a section taken along line 8--8 in FIG. 5,
FIG. 9 is a diagrammatic cross section taken through a third embodiment of the mixing chamber,
FIG. 10 is a section taken along line 10--10 in FIG. 9,
FIG. 11 is a section taken along line 11--11 in FIG. 9, and
FIG. 12 is a section taken along line 12--12 in FIG. 9.
The internal combustion engine 1 represented diagrammatically in FIG. 1 has two cylinder banks 2 and 3 whose exhaust pipes 4, 5 and 6, and 7, 8 and 9, respectively, are combined in exhaust manifolds 10 and 11, respectively. Each manifold 10 and 11 is connected to a divergent wye coupling 12 and 13, respectively, from which two connecting pipes 14, 15, and 16, 17, respectively run. Connecting pipe 15 is connected to a convergent wye coupling 18 into which the branch pipe 17 runs. In the same manner the connecting pipe 16 is connected to a convergent wye coupling 19 into which the connecting pipe 14 runs. An exhaust pipe 20 runs from the convergent wye 15 [18] to a first reactor 21 and a second exhaust pipe 22 runs from the second
REFERENCES:
patent: 3943710 (1976-03-01), Lange
patent: 4305249 (1981-12-01), Schmid
Bathelt Hartmut
Damm Gunter
Hoffmann Henning
Kromer Gunter
Nowitzki Friedhelm
Audi AG
Hart Douglas
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