Air-fuel ratio feedback control apparatus of internal combustion engine and method thereof
AssigneeUnisia Jecs Corporation
InventorsKoji Takahashi, Shigeo Ohkuma, Hajime Hosoya, Hidekazu Yoshizawa
Life of this patent
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Abstract
In a sliding mode control for restraining an air-fuel ratio state on a switching line set on a phase plane shown by a deviation between an actual air-fuel ratio and a target air fuel ratio, and a differential value of the deviation, an inclination of the switching line is made small, when the smaller an intake air quantity is, the longer a detection delay time of the air-fuel ratio is.
Claims18
An air-fuel ratio feedback control apparatus for controlling an air-fuel ratio of a combustion mixture in an internal combustion engine to a target air-fuel ratio, comprising:
- an air-fuel ratio sensor for detecting said air-fuel ratio;
- a fuel injection valve for injecting fuel into said internal combustion engine;
- and
- a control unit for feedback controlling a fuel injection quantity of said fuel injection valve so that an actual air-fuel ratio detected by said air-fuel ratio sensor is in conformity with a target air-fuel ratio, by a sliding mode control for restraining an air-fuel ratio state on a switching line set on a phase plane shown by a deviation between said actual air-fuel ratio detected by said air-fuel ratio sensor and said target air fuel ratio and a differential value of said deviation,
- wherein said control unit changes an inclination of said switching line in accordance with a change in dead time of said feedback control based upon engine operating conditions.
An air fuel ratio feedback control apparatus for controlling an air-fuel ratio of a combustion mixture in an internal combustion engine to a target air-fuel ratio, comprising:
- a deviation computing unit for computing a deviation between an actual air-fuel ratio and the target air-fuel ratio;
- a differential value computing unit for computing a differential value of said deviation;
- a nonlinear portion computing unit for computing a nonlinear portion, using said deviation and a differential value of deviation when an inclination is K and a switching function is S, as
- S=K×(deviation−predetermined value)+differential value of deviation, and
- nonlinear portion=nonlinear portion gain×S/|S|;
- a linear portion computing unit for computing a linear portion using said deviation, as
- linear portion=linear portion gain×deviation;
- a feedback correction coefficient computing unit for computing a feedback correction coefficient for correcting a fuel injection quantity into said engine based upon said nonlinear portion and said linear portion;
- a basic value computing unit for computing a basic value K1 of said inclination K based upon an engine intake air quantity;
- a transitional correction term computing unit for computing a transient correction factor K2 based upon a differential value of said intake air quantity;
- and
- an inclination computing unit for computing said inclination K based upon said basic value K1 and said transient correction term K2.
An air fuel ratio feedback control apparatus for controlling an air-fuel ratio of a combustion mixture in an internal combustion engine to a target air-fuel ratio, comprising:
- a deviation computing unit for computing a deviation between an actual air-fuel ratio and the target air-fuel ratio;
- a differential value computing unit for computing a differential value of said deviation;
- a nonlinear portion computing unit for computing a nonlinear portion, using said deviation and a differential value of deviation when an inclination is K and a switching function is S, as
- S=K×(deviation−predetermined value)+differential value of deviation, and
- nonlinear portion=nonlinear portion gain×S/|S|;
- a linear portion computing unit for computing a linear portion using said deviation, as
- linear portion=linear portion gain×deviation;
- a feedback correction coefficient computing unit for computing a feedback correction coefficient for correcting a fuel injection quantity into said engine based upon said nonlinear portion and said linear portion;
- a basic value computing unit for computing a basic value K1 of said inclination K based upon an engine rotation speed;
- a transitional correction term computing unit for computing a transient correction factor K2 based upon a differential value of said engine rotation speed;
- and
- an inclination computing unit for computing said inclination K based upon said basic value K1 and said transient correction term K2.
An air fuel ratio feedback control method for controlling an air-fuel ratio of a combustion mixture in an internal combustion engine to a target air-fuel ratio, comprising the steps:
- changing an inclination of a switching line set on a phase plane shown by a deviation between said actual air-fuel ratio detected by said air-fuel ratio sensor and said target air fuel ratio and a differential value of said deviation in accordance with a change in dead time of a feedback control based upon engine operating conditions;
- and
- feedback controlling an actual air-fuel ratio to the target air-fuel ratio by a sliding mode control for restraining an air-fuel ratio state on said switching line.
Dependencies are inferred from the claim text.