Honda Motor Co., Ltd.

Soichiro Goto

Seiji Watanabe

Michinori Tani

Atsuhiro Miyauchi

Kenichi Maeda

Hiroyuki Ando

Takeshi Aoki

Tooru Sekiguchi

An air-fuel ratio control system for an internal combustion engine, which, at the resumption of air-fuel ratio feedback control, is capable of setting the initial value of an integral term of the feedback control to a value properly learned in preceding feedback control, thereby enabling improvement of control accuracy. To feedback-control the output value of an O2 sensor to a target value, a target air-fuel ratio is calculated. During the feedback control, when it is determined that a predetermined condition in which it is estimated that exhaust gas air-fuel ratio upstream of the catalyst is excellently reflected on an exhaust gas air-fuel ratio at a location midway or downstream of the catalyst is satisfied, an adaptive law input calculated immediately before interruption of the feedback control is updated and stored as the initial value of an integral term for the following execution of the feedback control.

Air-fuel ratio control system for internal combustion engine

An apparatus for controlling an air-fuel ratio of an internal-combustion engine includes an air-fuel ratio detector, a fluctuation signal generating device, an air-fuel ratio fluctuation device, a 0.5th-order frequency component strength calculator, a fluctuation frequency component strength calculator, a reference component strength calculator, and an imbalance fault determining device. The reference component strength calculator is configured to calculate strength of a reference component in accordance with strength of a first frequency component and strength of a second frequency component. The imbalance fault determining device is configured to make a determination of an imbalance fault in which air-fuel ratios of a plurality of cylinders vary beyond a tolerance limit on a basis of a relative relationship between strength of the 0.5th-order frequency component and the strength of the reference component.

Apparatus for controlling air-fuel ratio of internal-combustion engine

An air-fuel ratio control apparatus for an internal combustion engine includes an air-fuel ratio sensor having an output characteristic which is nonlinear with respect to the air-fuel ratio of exhaust gas. An output deviation converter is configured to convert an output deviation to a first predetermined value if an output value of the air-fuel ratio sensor is on a richer side of a predetermined target value and to a second predetermined value if the output value is on a leaner side of the target value. A control input calculator is configured to calculate a control input to feedback-control the output value of the air-fuel ratio sensor such that the output deviation converted by the output deviation converter is to be zero. An air-fuel ratio controller is configured to control the air-fuel ratio of exhaust gas using the control input calculated by the control input calculator.

Air-fuel ratio control apparatus for internal combustion engine

An air-fuel ratio control apparatus for an internal-combustion engine includes an air-fuel-ratio sensor, a control-input calculator, an air-fuel-ratio controller, and a gain calculator. The air-fuel-ratio sensor is disposed in an exhaust channel in the internal-combustion engine and is configured to detect an air-fuel ratio in exhaust gas. The control-input calculator is configured to calculate a control input in accordance with an output value of the air-fuel-ratio sensor. The air-fuel-ratio controller is configured to perform a feedback control using the control input such that the output value of the air-fuel-ratio sensor reaches a target value. The gain calculator is configured to calculate a gain in accordance with the output value when the output value is leaner than the target value. The gain is to be used in calculating the control input.

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Wako, Japan

Soichiro Goto