Air/fuel control system and method
First Claim
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1. A fuel error and purge flow estimation method for an engine having an exhaust gas sensor, said method comprising the steps of:
- modulating a purge flow entering the engine with a predetermined modulation scheme;
calculating a fueling difference in response to a difference between a desired air/fuel ratio and a measured exhaust air/fuel ratio; and
simultaneously mapping said fueling difference to a fueling error and to an estimated purge flow based on said modulation scheme and a change in engine operating conditions to appropriately assign said fueling difference to said fueling error and said estimated purge flow.
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Abstract
An air/ratio control system and method for an internal combustion engine coupled to a fuel vapor recovery system simultaneously maps a difference between a desired air/fuel ratio and a measured air/fuel ratio to fueling errors and a purge vapor flow. This system and method maximizes the ability to purge the vapor recovery system while maintaining the ability to diagnose fuel errors.
12 Citations
17 Claims
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1. A fuel error and purge flow estimation method for an engine having an exhaust gas sensor, said method comprising the steps of:
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modulating a purge flow entering the engine with a predetermined modulation scheme; calculating a fueling difference in response to a difference between a desired air/fuel ratio and a measured exhaust air/fuel ratio; and simultaneously mapping said fueling difference to a fueling error and to an estimated purge flow based on said modulation scheme and a change in engine operating conditions to appropriately assign said fueling difference to said fueling error and said estimated purge flow. - View Dependent Claims (2, 3, 4, 5, 6)
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7. An air/fuel ratio control method for an engine having an exhaust gas sensor and a vapor recovery system, said method comprising the steps of:
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modulating a purge flow entering the engine with a predetermined modulation scheme; calculating a fueling difference in response to a difference between a desired air/fuel ratio and a measured exhaust air/fuel ratio; simultaneously mapping said fueling difference to a fueling error and to an estimated purge flow based on said modulation scheme and a change in engine operating conditions to appropriately assign said fueling difference to said fueling error and said estimated purge flow; creating a desired fuel quantity to deliver to the engine in response to an inducted fresh air charge quantity; and adjusting said desired fuel quantity by removing said fueling error from said desired fuel quantity. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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14. An air/fuel ratio control system for an internal combustion engine coupled to an a vapor recovery system, said system comprising:
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an exhaust sensor for indicating an air/fuel ratio of exhaust gas exiting the engine; a fuel delivery system for delivering fuel into the engine; a control valve for controlling a purge flow entering the engine; a controller for modulating a purge flow entering the engine with a predetermined modulation scheme, calculating a fueling difference in response to a difference between a desired air/fuel ratio and said indicated exhaust air/fuel ratio, simultaneously mapping said fueling difference to a fueling error and to an estimated purge flow based on said modulation scheme and a change in engine operating conditions to appropriately assign said fueling difference to said fueling error and said estimated purge flow, creating a desired fuel quantity to delivery to the engine in response to an inducted fresh air charge quantity, adjusting said desired fuel quantity by removing said fueling error from said desired fuel quantity, and creating an actuation signal to cause said fuel delivery system to delivery said adjusted desired fuel quantity to the engine. - View Dependent Claims (15, 16, 17)
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Specification