Engine control to achieve rapid catalyst warm-up
AssigneeFord Motor Company
InventorsDaniel L. Meyer, Douglas R. Hamburg, Philip W. Husak, Steven R. Whittier
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Abstract
A system and method to control the ignition timing of engine (28) are used to rapidly warm a catalytic converter (52). A controller (8) calculates (402) hydrocarbon efficiency of the converter (52) from a ratio of the integrals of hydrocarbon sensors respectively positioned downstream (48) and upstream (46) of the converter (52). The controller retards ignition timing to a value retarded from nominal ignition timing (416, 426) when the calculated hydrocarbon efficiency is less than a desired efficiency (418).
Claims9
A control method for an internal combustion engine having its exhaust coupled to a catalytic converter, comprising the steps of:
- providing an indication of hydrocarbons downstream of said converter;
- calculating hydrocarbon efficiency of said converter from said hydrocarbon indication;
- providing an indication of low catalytic converter efficiency;
- and
- retarding ignition timing to a value retarded from nominal ignition timing during said indication of low catalytic converter efficiency and advancing said ignition timing back towards said nominal timing when said calculated hydrocarbon efficiency reaches a desired efficiency.
A control method for an internal combustion engine having its exhaust coupled to a catalytic converter, comprising the steps of:
- providing an indication of hydrocarbons downstream of said converter;
- calculating hydrocarbon efficiency of said converter from said hydrocarbon indication wherein said step of calculating converter efficiency is further responsive to an indication of hydrocarbons upstream of the converter;
- and
- retarding ignition timing to a value retarded from nominal ignition timing when said calculated hydrocarbon efficiency is less than a desired efficiency.
A control method for an internal combustion engine having its exhaust coupled to a catalytic converter, comprising the steps of:
- providing an indication of hydrocarbons downstream of said converter;
- calculating hydrocarbon efficiency of said converter from said hydrocarbon indication wherein said step of calculating converter efficiency is further responsive to an indication of hydrocarbons upstream of the converter and wherein said step of calculating converter efficiency further comprises a step of calculating a ratio of an integral of said downstream hydrocarbon indication to an integral of said upstream hydrocarbon indication;
- and
- retarding ignition timing to a value retarded from nominal ignition timing when said calculated hydrocarbon efficiency is less than a desired efficiency.
A control method for an internal combustion engine having its exhaust coupled to a catalytic converter, comprising the steps of:
- providing an indication of hydrocarbons downstream of said converter;
- calculating hydrocarbon efficiency of said converter from said hydrocarbon indication;
- retarding ignition timing to a value retarded from nominal ignition timing when said calculated hydrocarbon efficiency is less than a desired efficiency;
- offsetting a mixture of air and fuel inducted into the engine by a predetermined amount in a lean direction to shift engine exhaust gas mixture towards an air/fuel ratio lean of stoichiometry by a preselected amount;
- correcting said predetermined air/fuel mixture offset by a correction value so that said exhaust gas mixture is shifted more closely to said lean offset from stoichiometry;
- adjusting said inducted air/fuel mixture in response to a feedback variable derived by integrating an output of an exhaust gas oxygen sensor to maintain said exhaust gas mixture at said preselected offset from stoichiometry during said period;
- and
- adaptively learning said correction value by comparing said feedback variable to a reference value.
A control system for an internal combustion engine having its exhaust coupled to a catalytic converter, comprising:
- a first and a second hydrocarbon sensor respectively positioned upstream and downstream of the converter;
- a controller calculating hydrocarbon efficiency of the converter from output signals from said first and said second hydrocarbon sensors;
- said controller retarding ignition timing to a value retarded from nominal ignition timing when said calculated hydrocarbon efficiency is less than a desired efficiency;
- and
- said controller offsetting a fuel command for delivering fuel to the engine by a predetermined amount in a lean direction during a period after engine start to shift engine exhaust gas mixture towards a preselected air/fuel ratio lean of stoichiometry by a preselected amount.
Dependencies are inferred from the claim text.