Method of protecting a catalytic converter
AssigneeRobert Bosch GmbH
InventorsMichael Baeuerle, Klaus Ries-Mueller
Life of this patent
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Abstract
The invention is directed to a method for protecting a catalytic converter in the exhaust gas of an internal combustion engine in a starting operation of the engine. An index is formed for the quantity of an air/fuel mixture which will first react exothermally in the catalytic converter downstream of the engine. The index is compared to a predetermined threshold value and fuel metering is cut off when the threshold value is exceeded.
Claims6
A method for protecting a catalytic converter in the exhaust gas of an internal combustion engine in a starting operation of said engine, the method comprising the steps of:
- forming a first index (MZU) for the quantity of an air/fuel mixture which has been metered to said engine and which first reacts exothermally in said catalytic converter downstream of said engine;
- recognizing combustions by summing the amounts of the differences between neighboring maxima and minima of the trace of engine speed (rpm) over a camshaft revolution;
- comparing said amounts to an operating-point dependent threshold value;
- deeming combustions as started when said operating-point dependent threshold value is exceeded;
- forming a second index (MV) for an air/fuel quantity which had been combusted;
- forming a third index (dM) as a difference of said first and second indices (MZU-MV);
- comparing said third index (dM) to a predetermined threshold value;
- and,
- cutting off the metering of fuel when said threshold value is exceeded.
A method for protecting a catalytic converter in the exhaust gas of an internal combustion engine in a starting operation of said engine, the method comprising the steps of:
- forming a first index (MZU) for the quantity of an air/fuel mixture which has been metered to said engine and which first reacts exothermally in said catalytic converter downstream of said engine;
- determining said first index as the air/fuel quantity which has been metered from the beginning of said starting operation up to the onset of combustions;
- forming a second index (MV) for an air/fuel quantity which had been combusted;
- forming said second index (MV) by determining the number of combustions which have actually taken place since the beginning of said starting operation;
- evaluating the difference between the maximum and the minimum of the trace of the engine speed between two ignitions;
- counting as a combustion when said difference exceeds a predetermined threshold;
- forming a third index (dM) as a difference of said first and second indices (MZU-MV);
- comparing said third index (dM) to a predetermined threshold value;
- and,
- cutting off the metering of fuel when said threshold value is exceeded.
A method for protecting a catalytic converter in the exhaust gas of an internal combustion engine in a starting operation of said engine, the method comprising the steps of:
- forming an index for the quantity of an air/fuel mixture which first reacts exothermally in said catalytic converter downstream of said engine;
- comparing said index to a predetermined threshold value;
- said index being a first index (dM) and forming a second index (MZU) for an air/fuel mixture quantity which has been metered to said engine since the beginning of said starting operation;
- forming a third index (MV) for an air/fuel quantity which had been combusted since the beginning of said starting operation;
- forming said first index (dM) as a difference of said second and third indices (MZU-MV);
- forming said third index (MV) by determining the number of combustions which have actually taken place since the beginning of said starting operation;
- evaluating the difference between the maximum and the minimum of the trace of the engine speed between two ignitions;
- counting as a combustion when said difference exceeds a predetermined threshold;
- the threshold value being dependent upon operating parameters of said engine;
- and,
- cutting off the metering of fuel when said threshold value is exceeded.
Dependencies are inferred from the claim text.