Method and system for pre-ignition control
First Claim
1. A method of operating an engine, comprising,in response to an indication of pre-ignition in a cylinder,operating the cylinder with a first air to injected fuel ratio richer than stoichiometry for a first number of combustion events;
- andafter the first number of combustion events has elapsed, operating the cylinder with a second air to injected fuel ratio leaner than stoichiometry for a second number of combustion events.
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Accused Products
Abstract
Methods and systems are provided for mitigating engine pre-ignition based on a feed-forward likelihood of pre-ignition and feedback from a pre-ignition event. In response to an indication of pre-ignition, a cylinder may be enriched while an engine load is limited. The enrichment may be followed by an enleanment to restore exhaust catalyst feed-gas oxygen levels. The mitigating steps may be adjusted based on engine operating conditions, a pre-ignition count, as well as the nature of the pre-ignition.
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Citations
19 Claims
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1. A method of operating an engine, comprising,
in response to an indication of pre-ignition in a cylinder, operating the cylinder with a first air to injected fuel ratio richer than stoichiometry for a first number of combustion events; - and
after the first number of combustion events has elapsed, operating the cylinder with a second air to injected fuel ratio leaner than stoichiometry for a second number of combustion events. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A method of operating an engine, comprising,
limiting an engine load based on a likelihood of pre-ignition; - and
in response to an occurrence of pre-ignition in a cylinder, operating the cylinder with a first air-to-fuel ratio richer than stoichiometry for a first duration; transitioning the cylinder from the first air-to-fuel ratio to a second air-to-fuel ratio leaner than stoichiometry for a second duration, one or more of the second air-to-fuel ratio and second duration based on the first air-fuel-ratio and/or first duration; and further limiting the engine load, wherein basing the second air-to-fuel ratio and second duration on the first air-fuel-ratio and/or first duration includes increasing a degree of leanness of the second air-to-fuel ratio and increasing the second duration as a degree of richness of the first air-to-fuel ratio and/or the first duration increases. - View Dependent Claims (15, 16, 17, 18)
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19. A method of operating an engine, comprising,
limiting an engine load based on a likelihood of pre-ignition; - and
in response to an occurrence of pre-ignition in a cylinder, operating the cylinder with a first air-to-fuel ratio richer than stoichiometry for a first duration; transitioning the cylinder from the first air-to-fuel ratio to a second air-to-fuel ratio leaner than stoichiometry for a second duration, one or more of the second air-to-fuel ratio and second duration based on the first air-fuel-ratio and/or first duration; further limiting the engine load; and
transitioning the cylinder from the second air-to-fuel ratio to a third air-to-fuel ratio at stoichiometry.
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Specification