Power plants – Internal combustion engine with treatment or handling of... – Methods
Patent
1997-04-22
1999-07-27
Denion, Thomas E.
Power plants
Internal combustion engine with treatment or handling of...
Methods
60276, 60277, F01N 300
Patent
active
059270683
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a method and an apparatus for monitoring the functioning of a catalytic converter.
BACKGROUND INFORMATION
A method and an apparatus for monitoring a catalytic converter are known from U.S. Pat. No. 5,182,907. A sensor is arranged in front of and behind the catalytic converter, in each instance, to detect the proportion of hydrocarbons in the exhaust gas. A defect of the catalytic converter is recognized on the basis of a comparison between the hydrocarbon content in front of and behind the catalytic converter. A disadvantage here is that two sensors are required.
The exhaust gases of self-ignition internal combustion engines tend to produce high NOx emissions, because of the fact that they are operated with a great excess of air. This occurs to an even greater degree in internal combustion engines with direct fuel injection into the combustion space. A reduction catalytic converter can be used to reduce these emissions. To reduce the NOx levels, additional fuel is metered in ahead of the catalytic converter, and this fuel is converted in the catalytic converter.
Furthermore, it is provided that in the case of diesel engines, the exhaust gas is subsequently treated by an oxidation catalytic converter. This makes it possible to clearly lower the hydrocarbon emissions (HC emissions). Such a method of procedure is described, for example, in German Patent No. 4441261.
In the United States, so-called On-Board-Diagnosis (OBD) is required. This means that certain components are constantly monitored, and defects, particularly a deterioration in the exhaust gas emission values of the engine, are reported to the driver. For the NOx catalytic converter, monitoring is required because of the amount of fuel that is metered in.
SUMMARY OF THE INVENTION
The present invention is based on the task of making available a diagnosis method and a diagnosis device which can diagnose a decrease in effect both for an oxidation catalytic converter and for a NOx catalytic converter, with little effort.
With the method of procedure according to the present invention, it is possible to recognize a decrease in effect of the catalytic converters, while they are in operation.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows an overall view of the internal combustion engine and the catalytic converter.
FIG. 2 shows a block schematic according to the present invention.
FIG. 3 shows a flow diagram of a first embodiment, according to the present invention.
FIG. 4 shows a block schematic according to the present invention.
FIG. 5 shows a flow diagram of a second embodiment of the diagnosis method according to the present invention.
DETAILED DESCRIPTION
In FIG. 1, an internal combustion engine 100 is shown schematically. This is preferably a self-ignition internal combustion engine. Fresh air is supplied to the internal combustion engine via an intake line 105, and the exhaust gases of the internal combustion engine are passed away via an exhaust gas line 110. A reduction catalytic converter 115 as well as an oxidation catalytic converter 120 are arranged in the exhaust gas line. It is particularly advantageous if the two catalytic converters form a structural entity.
A temperature sensor 125 detects the exhaust gas temperature T. By means of a metering device 130, an amount QD of fuel which is dependent on operating variables can be supplied to the exhaust gas. Furthermore, a hydrocarbon sensor 135 (HC sensor) is provided, which detects the proportion of uncombusted hydrocarbons (HC) in the exhaust gas. This sensor 135 yields a signal which corresponds to the proportion of hydrocarbons.
A speed of rotation sensor 140 detects the speed of rotation N of the internal combustion engine 100. A fuel metering unit 145 meters a pre-determined amount QK of fuel into the internal combustion engine 100.
A sensor 150 detects the amount QL of air taken in. A control unit 155 processes the signals which come from the sensors 125, 135, 140, and 150. The control unit 155 in turn acts on the fu
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Denion Thomas E.
Robert & Bosch GmbH
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