Method and apparatus for enhancing fuel economy of a lean burn internal combustion engine
First Claim
1. 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 distance effectively traveled by a vehicle during a first engine operating period, wherein the distance is based upon an accumulation of the greater of an instantaneous vehicle speed and a minimum predetermined vehicle speed.
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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
30 Claims
- 1. 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 distance effectively traveled by a vehicle during a first engine operating period, wherein the distance is based upon an accumulation of the greater of an instantaneous vehicle speed and a minimum predetermined vehicle speed.
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15. 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 distance effectively traveled by a vehicle during a first engine operating period, wherein the distance is based upon an accumulation of the greater of an instantaneous vehicle speed and a minimum predetermined vehicle speed. - View Dependent Claims (16, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
determining a total amount of the exhaust gas constituent exhausted to the atmosphere during the first engine operating period;
calculating an evaluative measure based on the total amount and the distance effectively traveled; and
prohibiting a lean engine operating condition when the evaluative measure exceeds a predetermined threshold.
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25. The method of claim 24, wherein determining the total amount includes periodically determining an instantaneous amount of the exhaust gas constituent being exhausted to the atmosphere, and accumulating the instantaneous amounts during the first engine operating period.
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26. The method of claim 25, wherein the instantaneous amount is based upon an output signal generated by a sensor positioned downstream of the device.
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27. The method of claim 25, wherein the instantaneous amount is determined as a function of instantaneous engine operating conditions and an instantaneous device storage efficiency.
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28. The method of claim 24, wherein the predetermined threshold is periodically adjusted based upon an indication of vehicle activity.
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29. The method of claim 28, including determining the indication of vehicle activity based on vehicle power.
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30. The method of claim 28, including determining the indication of vehicle activity based on engine power.
Specification