Engine air-fuel ratio controller and control method
AssigneeNissan Motor Co., Ltd.
InventorRitsuo Sato
Life of this patent
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Abstract
When an engine (1) is in an idle state and the engine rotation speed exceeds a predetermined value, fuel supply is stopped. In this state, fuel supply is resumed when there is a shift to a non-idle state or when the engine rotation speed falls below a predetermined value. The oxygen adsorption amount of a three-way catalyst during the time period when fuel supply is stopped, is calculated. The air-fuel ratio is made richer according to the oxygen adsorption amount of the three-way catalyst when fuel supply is resumed. By limiting the richness of the air-fuel ratio at this time, fluctuations of engine output torque in the idle running state are suppressed.
Claims18
An air-fuel ratio controller for use with an engine which performs combustion of a mixture of fuel injected from a fuel injector and air aspirated from an intake passage, wherein exhaust gas produced by combustion is purified by a catalytic converter comprising a three-way catalyst, said controller comprising:
- a sensor for detecting whether or not said engine is running in an idle state,
- a sensor for detecting a rotation speed of said engine, and
- a microprocessor programmed to:
- stop fuel injection from the fuel injector when the engine is in the idle state and the engine rotation speed exceeds a predetermined fuel cut permitted rotation speed,
- calculate an oxygen amount adsorbed on said three-way catalyst while said injection has stopped,
- increase the amount of fuel injected from said fuel injector when said fuel injection is resumed, by an increase amount according to said adsorbed oxygen amount, and
- limit said increase amount to a predetermined limiting value.
An air-fuel ratio controller for use with an engine which performs combustion of a mixture of fuel injected from a fuel injector and air aspirated from an intake passage, wherein exhaust gas produced by combustion is purified by a catalytic converter comprising a three-way catalyst, said controller comprising:
- means for detecting whether or not said engine is running in an idle state,
- means for detecting a rotation speed of said engine, and
- means for stopping fuel injection from the fuel injector when the engine is in the idle state and the engine rotation speed exceeds a predetermined fuel cut permitted rotation speed,
- means for calculating an oxygen amount adsorbed on said three-way catalyst while said injection has stopped,
- means for increasing the amount of fuel injected from said fuel injector when said fuel injection is resumed, by an increase amount according to said adsorbed oxygen amount, and
- means for limiting said increase amount to a predetermined limiting value.
An air-fuel ratio control method of an engine which performs combustion of a mixture of fuel injected from a fuel injector and air aspirated from an intake passage, wherein exhaust gas produced by combustion is purified by an catalytic converter comprising a three-way catalyst, said method comprising:
- detecting whether or not said engine is running in an idle state,
- detecting a rotation speed of said engine,
- stopping fuel injection from the fuel injector when the engine is in the idle state and the engine rotation speed exceeds a predetermined fuel cut permitted rotation speed,
- calculating an oxygen amount adsorbed on said three-way catalyst while said injection has stopped,
- increasing the amount of fuel injected from said fuel injector when said fuel injection is resumed, by an increase amount according to said adsorbed oxygen amount, and
- limiting said increase amount to a predetermined limiting value.
Dependencies are inferred from the claim text.