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US 9,175,615 B2Granted
Method and system for engine control
AssigneeFord Global Technologies, LLC
InventorsEd Badillo, Samuel Guido, Ross Dykstra Pursifull, Dev Saberwal
Life of this patent
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Abstract
Methods and systems are provided for reducing exhaust temperatures during high engine load conditions in engine systems configured to operate with multiple fuels. Stoichiometric cylinder operation is provided via injection of a gaseous fuel such as CNG. In response to elevated exhaust temperatures, the cylinder is enriched by injecting a liquid fuel, such as gasoline, while maintaining the injection of CNG and while maintaining spark timing at MBT.
Claims19
A method for an engine, comprising:
- during high load conditions, when operating with a first gaseous fuel, in response to an elevated exhaust temperature, enriching the engine via injection of a second, liquid fuel while maintaining spark timing;
- wherein a larger degree of enrichment with the second liquid fuel is provided based on a widened flammability limit of the second fuel, and the elevated exhaust temperature, and wherein the operating includes combusting a mixture of the first and second fuels via spark ignition in the cylinder.
An engine method, comprising:
- port injecting a first amount of a first, gaseous fuel into an engine cylinder to provide a stoichiometric combustion air-fuel ratio;
- and
- in response to elevated exhaust temperatures, while maintaining injection of the first amount of the first fuel, and while maintaining spark timing, direct injecting a second amount of a second, liquid fuel into the cylinder to provide a richer than stoichiometry combustion air-fuel ratio, and combusting a mixture of the first and second fuels via spark ignition in the cylinder;
- and
- in response to reaching a threshold richer than stoichiometry combustion air-fuel ratio, maintaining injection of the first amount of first fuel and the second amount of second fuel, and addressing elevated exhaust temperatures using throttle adjustments.
2 more elements
An engine system, comprising:
- an engine cylinder;
- a first port injector configured to port inject a first, gaseous fuel into the cylinder;
- a second direct injector configured to direct inject a second, liquid fuel into the cylinder;
- a spark plug for igniting a fuel mixture in the cylinder;
- and
- a controller with computer readable instructions for:
- operating the cylinder at stoichiometry by injecting a variable ratio of the first fuel and the second fuel;
- and
- in response to elevated exhaust temperatures, enriching the cylinder by selectively increasing injection of the second fuel while maintaining injection of the first fuel and while also maintaining spark ignition timing at MBT, a larger enrichment provided based on a widened flammability limit of the second fuel and the elevated exhaust temperature and wherein the operating includes combusting a mixture of the first and second fuels via spark ignition in the cylinder.
6 more elements
Dependencies are inferred from the claim text.