Honda Motor Co., Ltd.

Tooru Sekiguchi

Seiji Watanabe

Michinori Tani

Atsuhiro Miyauchi

Takeshi Aoki

Hiroyuki Ando

Takashi Yanagiura

Soichiro Goto

Kazunori Kawamura

An air-fuel ratio control apparatus includes an air-fuel ratio detector, an oscillation signal generator, an air-fuel ratio oscillation device, a sum/difference frequency component intensity calculator, a decision parameter calculator, and an imbalance failure determination device. The sum/difference frequency component intensity calculator is configured to calculate, while the air-fuel ratio oscillation device is in operation, at least one of a component intensity of a difference frequency and a component intensity of a sum frequency. The decision parameter calculator is configured to calculate, according to at least one of the component intensity of the difference frequency and the component intensity of the sum frequency, a decision parameter to determine a degree of imbalance of an air-fuel ratio. The imbalance failure determination device is configured to determine an imbalance failure in which the degree of imbalance of the air-fuel ratio exceeds an allowable limit using the decision parameter.

Air-fuel ratio control apparatus for internal combustion engine and method for controlling air-fuel ratio

An air-fuel ratio control apparatus for an internal combustion engine includes an air-fuel ratio detector, a fuel amount controller, an operational state parameter acquiring device, an extractor, a failure determination device, a variation state parameter calculator, and a determination stopping device. The operational state parameter acquiring device is configured to acquire at least one operational state parameter. The failure determination device is configured to execute failure determination of determining a failure in an air-fuel ratio control system of the internal combustion engine based on a specific frequency component extracted by the extractor. The variation state parameter calculator is configured to calculate a variation state parameter. The determination stopping device is configured to stop the failure determination if the variation state parameter calculated by the variation state parameter calculator is equal to or larger than a predetermined threshold value.

Air-fuel ratio control apparatus for internal combustion engine

An air-fuel ratio control system for an internal combustion engine has a perturbation control which oscillates the air-fuel ratio with a first frequency. A first difference signal is generated indicative of a difference between a present value and a first past value from an air-fuel ratio sensor detected at a timing of a first specific period which is set to reduce a specific frequency component corresponding to a specific frequency different from the first frequency. A first frequency component is extracted. A second difference signal is generated indicative of a difference between a present value and a second past value detected at a timing of a second specific period which is set to reduce the first frequency component. The specific frequency component is extracted. A failure of the control system is determined by a relationship between intensities of the first frequency component and the specific frequency component.

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 abnormality determining apparatus includes an air-fuel ratio controller, an output change period parameter calculator, an output change amount extremum calculator, and an abnormality determining device. The abnormality determining device is configured to determine an abnormality of an air-fuel ratio sensor based on a relationship between an output change period parameter and an output change amount extremum.

Abnormality determining apparatus for air-fuel ratio sensor

An oscillation signal is generated to oscillate the air-fuel ratio with a set frequency which is different from a 0.5th-order frequency (half of the frequency corresponding to a rotational speed of the engine). Air-fuel ratio perturbation control is performed to oscillate the air-fuel ratio according to the oscillation signal. An intensity of the 0.5th-order frequency component and the set frequency component contained in the detected air-fuel ratio signal are calculated. A determination parameter applied to determining an imbalance degree of air-fuel ratios corresponding to the plurality of cylinders is calculated according to the two intensities and determines an imbalance failure that the imbalance degree of the air-fuel ratios exceeds an acceptable limit. A predicted imbalance value, indicative of a predicted value of the imbalance degree, is calculated, and an amplitude of the oscillation signal is set according to the predicted imbalance value.

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Wako, Japan

Tooru Sekiguchi