Method of learn-controlling air-fuel ratio for internal combustion engine
AssigneeToyota Jidosha Kabushiki Kaisha
InventorsToshimitsu Ito, Nobuyuki Kobayashi
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Abstract
In a method wherein a fuel injection time duration is allowed to perform a proportional-plus-integral action by the use of an air-fuel ratio feedback correction coefficient obtained from the output of an O.sub.2 sensor thereby to control an air-fuel ratio to a target air-fuel ratio, a correction value for allowing a mean value of the air-fuel ratio feedback correction coefficient to approach a predetermined value is varied every time the air-fuel ratio feedback correction coefficient skips a plurality of times, thereby to learn-control the air-fuel ratio of an air-fuel mixture to be a stoichiometric one.
Claims5
A method of learn-controlling an air-fuel ratio for an internal combustion engine, comprising the steps of:
- (a) obtaining a basic fuel injection time duration in accordance with an engine load and an engine speed;
- (b) obtaining an air-fuel ratio feedback correction coefficient for allowing a fuel injection time duration to perform a proportional-plus-integral action in accordance with an output signal from an oxygen sensor for detecting a residual oxygen concentration in an exhaust gas;
- (c) varying a correction value for allowing a mean value of said air-fuel ratio feedback correction coefficient to approach a predetermined value corresponding to a target air-fuel ratio, every time said air-fuel ratio feedback correction coefficient skips a plurality of times;
- and
- (d) controlling the air-fuel ratio in accordance with said basic fuel injection time duration, said air-fuel ratio feedback correction coefficient and said correction value.
A method of learn-controlling an air-fuel ratio for an internal combustion engine, comprising the steps of:
- (a) obtaining a basic fuel injection time duration TP in accordance with an engine load and an engine speed;
- (b) obtaining an air-fuel ratio feedback correction coefficient FAF for allowing a fuel injection time duration TAU to perform a proportional-plus-integral action in accordance with an output signal from an oxygen sensor for detecting a residual oxygen concentration in an exhaust gas;
- (c) varying, when a throttle valve is at fully closed position, a correction value TAUG for allowing a mean value FAFAV of said correction coefficient FAF to approach a predetermined value corresponding to a target air-fuel ratio, every time said correction coefficient FAF skips a plurality of times, and varying, when the throttle valve is open, a correction value KG for allowing a mean value FAFAV of said correction coefficient FAF to approach the predetermined value corresponding to the target air-fuel ratio, every time said correction coefficient FAF skips a plurality of times;
- and
- (d) calculating a fuel injection time duration TAU through the following equation, thereby to control the air-fuel ratio
- TAU=(TP+TAUG).multidot.KG.multidot.FAF.multidot.(1+F)+.tau..sub.v
- where, F represents a correction coefficient employed in a transient operation state of the engine and .tau..sub.v represents a non-effective injection time duration.
Dependencies are inferred from the claim text.