Overall scheduling of a lean burn engine system
First Claim
1. A method for operating an engine in a plurality of modes, the method comprising:
- calculating a desired engine output;
determining whether the desired engine output is greater than a first available engine output that can be provided with less than all of the cylinders combusting air and fuel and remaining cylinders operating with air and substantially no injected fuel;
selecting a number of cylinders based on said determination; and
after said determination, indicating whether the desired engine output is greater than a second available engine output that can be provided with the selected combusting cylinders operating lean of stoichiometry.
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Accused Products
Abstract
A method is disclosed for controlling operation of an engine coupled to an exhaust treatment catalyst. Under predetermined conditions, the method operates an engine with a first group of cylinders combusting a lean air/fuel mixture and a second group of cylinders pumping air only (i.e., without fuel injection). In addition, the engine control method also provides the following features in combination with the above-described split air/lean mode: idle speed control, sensor diagnostics, air/fuel ratio control, adaptive learning, fuel vapor purging, catalyst temperature estimation, default operation, and exhaust gas and emission control device temperature control. In addition, the engine control method also changes to combusting in all cylinders under preselected operating conditions such as fuel vapor purging, manifold vacuum control, and purging of stored oxidants in an emission control device.
60 Citations
20 Claims
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1. A method for operating an engine in a plurality of modes, the method comprising:
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calculating a desired engine output; determining whether the desired engine output is greater than a first available engine output that can be provided with less than all of the cylinders combusting air and fuel and remaining cylinders operating with air and substantially no injected fuel; selecting a number of cylinders based on said determination; and after said determination, indicating whether the desired engine output is greater than a second available engine output that can be provided with the selected combusting cylinders operating lean of stoichiometry. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for controlling an engine having at least first and second groups of cylinders, the engine coupled to an emission control device, comprising:
allowing the engine to operate repeatedly in each of the following four modes; (1) operating the first group of cylinders with inducted air and substantially no injected fuel, and the second group of cylinders with a lean air-fuel mixture; (2) operating the first group of cylinders with inducted air and substantially no injected fuel, and the second group of cylinders with a substantially stoichiometric air-fuel mixture; (3) operating the first and the second group of cylinders with a lean air-fuel mixture; and (4) operating the first and the second group of cylinders with a substantially stoichiometric air-fuel mixtur. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method for controlling an engine having at least first and second groups of cylinders, the engine coupled to an emission control device, comprising:
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determining a desired engine output; allowing the engine to operate in each of the following four modes; (1) operating the first group of cylinders with inducted air and substantially no injected fuel, and the second group of cylinders with a lean air-fuel mixture; (2) operating the first group of cylinders with inducted air and substantially no injected fuel, and the second group of cylinders with a substantially stoichiometric air-fuel mixture; (3) operating the first and the second group of cylinders with a lean air-fuel mixture; and (4) operating the first and the second group of cylinders with a substantially stoichiometric or rich air-fuel mixture; selecting one of the four modes based on said desired engine output. - View Dependent Claims (19, 20)
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Specification