Method and apparatus for measuring lean-burn engine emissions
First Claim
1. A method for controlling the operation of an internal combustion engine in a motor vehicle, wherein the engine generates exhaust gas including an exhaust gas constituent, and wherein exhaust gas is directed through an emissions control device before being exhausted to the atmosphere, the device storing a quantity of the exhaust gas constituent when the exhaust gas directed through the device is lean of stoichiometry and releasing a previously-stored amount of the exhaust gas constituent when the exhaust gas directed through the device is rich of stoichiometry, the method comprising:
- determining a first measure representative of a total amount of the first exhaust gas constituent exhausted to the atmosphere during a first engine operating period;
determining a second measure representing a distance traveled by the vehicle during the first engine operating period; and
calculating a third measure based on the first measure and the second measure;
comparing the third measure to a predetermined threshold, the predetermined threshold being periodically adjusted based upon an indication of vehicle activity; and
discontinuing lean engine operation when the third measure exceeds the predetermined threshold.
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Accused Products
Abstract
A method and apparatus for controlling the operation of a “lean-burn” internal combustion engine in cooperation with an exhaust gas purification system having an emissions control device capable of alternatively storing and releasing NOx when exposed to exhaust gases that are lean and rich of stoichiometry, respectively, optimizes vehicle fuel economy while complying with emissions standards by prohibiting lean engine operation only when tailpipe emissions, calculated in terms of grams of an exhaust gas constituent per vehicle mile traveled, exceeds a permissible threshold value. The threshold value is preferably itself periodically determined based upon a detected or determined level of vehicle activity, such that vehicle activity characterized by greater transient engine operation prescribes a relatively lower level of permissible vehicle emissions.
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Citations
26 Claims
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1. A method for controlling the operation of an internal combustion engine in a motor vehicle, wherein the engine generates exhaust gas including an exhaust gas constituent, and wherein exhaust gas is directed through an emissions control device before being exhausted to the atmosphere, the device storing a quantity of the exhaust gas constituent when the exhaust gas directed through the device is lean of stoichiometry and releasing a previously-stored amount of the exhaust gas constituent when the exhaust gas directed through the device is rich of stoichiometry, the method comprising:
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determining a first measure representative of a total amount of the first exhaust gas constituent exhausted to the atmosphere during a first engine operating period;
determining a second measure representing a distance traveled by the vehicle during the first engine operating period; and
calculating a third measure based on the first measure and the second measure;
comparing the third measure to a predetermined threshold, the predetermined threshold being periodically adjusted based upon an indication of vehicle activity; and
discontinuing lean engine operation when the third measure exceeds the predetermined threshold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for controlling the operation of an internal combustion engine in a motor vehicle, wherein the engine generates exhaust gas including an exhaust gas constituent, and wherein exhaust gas is directed through an emissions control device before being exhausted to the atmosphere, the device storing a quantity of the exhaust gas constituent when the exhaust gas directed through the device is lean of stoichiometry and releasing a previously-stored amount of the exhaust gas constituent when the exhaust gas directed through the device is rich of stoichiometry, the method comprising:
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determining a first measure representative of a total amount of the first exhaust gas constituent exhausted to the atmosphere during a first engine operating period;
determining a second measure representing a distance traveled by the vehicle during the first engine operating period, wherein determining the second measure includes detecting a value representative of instantaneous vehicle speed, the detected value representative of instantaneous vehicle speed is clipped at a predetermined, nonzero minimum value; and
calculating a third measure based on the first measure and the second measure. - View Dependent Claims (10)
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11. A method for controlling an internal combustion engine of a vehicle, the engine coupled to an emissions control device, the method comprising:
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determining an amount of emissions exiting from the device per unit of distance traveled by the vehicle, wherein determining includes detecting a value representative of instantaneous vehicle speed, the detected value being clipped at a predetermined, nonzero minimum value; and
adjusting an engine operating parameter responsive to the determination.
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- 12. A controller for controlling an engine operating in combination with an emissions control device that releasably stores a constituent of exhaust gas generated by the engine when the engine is operated lean, wherein the controller is arranged to determine a first measure representative of a total amount of the first exhaust gas constituent exhausted to the atmosphere during a first engine operating period, and wherein the controller is further arranged to determine a value representative of instantaneous vehicle speed that is clipped at a predetermined, nonzero minimum value, to determine a second measure representing a distance traveled by the vehicle during the first engine operating period based on the clipped value, and to calculate a third measure based on the first measure and the second measure.
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19. A processor-readable storage medium including processor-executable code for controlling an engine operating in combination with an emissions control device that releasably stores a constituent of exhaust gas generated by the engine when the engine is operated lean, wherein the storage medium includes:
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code for determining a first measure representative of a total amount of the first exhaust gas constituent exhausted to the atmosphere during a first engine operating period;
code for determining a value representative of instantaneous vehicle speed that is clipped at a predetermined, nonzero minimum value;
code for determining a second measure representing a distance traveled by the vehicle during the first engine operating period based on the determined value;
code for generating a third measure based on the first measure and the second measure;
code for comparing the third measure to a predetermined threshold, the predetermined threshold being periodically adjusted based upon an indication of vehicle activity; and
code for discontinuing lean engine operation when the third measure exceeds the predetermined threshold. - View Dependent Claims (20, 21, 22, 23, 24, 25)
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26. A processor-readable storage medium including processor-executable code for controlling an engine operating in combination with an emissions control device that releasably stores a constituent of exhaust gas generated by the engine when the engine is operated lean, wherein the storage medium includes:
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code for determining a first measure representative of a total amount of the first exhaust gas constituent exhausted to the atmosphere during a first engine operating period;
code for determining a value representative of instantaneous vehicle speed that is clipped at a predetermined, nonzero minimum value;
code for determining a second measure representing a distance traveled by the vehicle during the first engine operating period based on a detected instantaneous vehicle speed value on the determined value; and
code for generating a third measure based on the first measure and the second measure.
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Specification