Method and system for pre-ignition control
AssigneeFord Global Technologies, LLC
InventorsChris Paul Glugla, Paul Charles Mingo, Robert Sarow Baskins, Sue Kay Wagers
Life of this patent
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Abstract
Methods and systems are provided for addressing pre-ignition that may be induced in response to actions taken to mitigate a cylinder misfire. An amount of engine load limiting applied may be adjusted to reduce the likelihood pre-ignition while also addressing component over-temperature issues. By limiting an engine load while shutting off fuel in a misfiring cylinder, and while combusting a lean air-fuel mixture in the remaining cylinders, pre-ignition induced by the misfire-mitigating lean combustion conditions can be reduced.
Claims19
A method of controlling an engine for preventing pre-ignition, comprising:
- operating a cylinder to pump air without injected fuel while another cylinder combusts a lean air-fuel mixture;
- and limiting an amount of intake air charge directed into the cylinders to be less than a threshold, the limiting increased as a degree of leanness of the air-fuel mixture increases.
A method of controlling an engine for preventing pre-ignition, comprising:
- in response to a misfire event:
- shutting off fuel to a first cylinder;
- operating a second cylinder with an air-to-fuel ratio leaner than stoichiometry;
- and limiting an amount of intake air charge directed into the second cylinder to be less than a threshold, the limiting increased as a degree of leanness of the air-fuel mixture increases.
A method of controlling an engine for preventing pre-ignition comprising:
- operating the engine in a first mode with all cylinders combusting at stoichiometry and with intake airflow adjusted to limit engine load to a first load limit;
- operating the engine in a second mode with a first number of cylinders pumping air without injected fuel, a second number of cylinders operating at an air-fuel ratio leaner than stoichiometry, and with intake airflow adjusted to limit engine load to a second load limit more restrictive than the first load limit at higher engine speeds, the first and second load limits based at least on engine speed;
- and
- operating the engine in a third mode with all cylinders combusting and at least one cylinder operating at an air-fuel ratio richer than stoichiometry, and with intake airflow adjusted to limit engine load to a third load limit more restrictive than the second load limit at lower engine speeds.
Dependencies are inferred from the claim text.