Toyota Jidosha Kabushiki Kaisha

Keiko Okamoto

Yuya Yoshikawa

Hiroaki Tsuji

Takeo Ogiso

An abnormality detection apparatus includes: an air/fuel ratio control portion that performs a control of fluctuating the air/fuel ratio between rich and lean states; a data acquisition portion that acquires, as data for detecting abnormality, a parameter that corresponds to responsiveness during change of output of the A/F sensor between rich and lean peaks during the control; a straight line setting portion that sets a straight line that represents a tendency of change of the parameter relative to change in intake air amount of the engine based on the data acquired by performing acquisition of the data a plurality of times; and an abnormality determination portion that determines the presence/absence of abnormality of the A/F sensor based on comparison between the gradient of the set straight line and an abnormality criterion value.

Abnormality detection apparatus and abnormality detection method for air/fuel ratio sensor

An abnormality detection apparatus includes: an air/fuel ratio control portion that performs a control of fluctuating the air/fuel ratio; a data acquisition portion that acquires, as data for detecting abnormality, a responsiveness parameter while output of the air/fuel ratio sensor changes between rich and lean peaks during the control; an abnormality determination portion that determines presence/absence of abnormality of the sensor by using the data; and a distribution width determination portion that finds a distribution width of the data acquired by performing a plurality of acquisitions of the data, in an increase/decrease direction of the data. On the basis of comparison between the distribution width and an abnormality criterion value, the abnormality determination portion determines that the sensor has abnormality if the distribution width is less than the criterion value, and determines that the sensor does not have abnormality if the distribution width is not less than the criterion value.

An abnormality detection apparatus includes: an air/fuel ratio control portion that controls of fluctuating the air/fuel ratio; a data acquisition portion that acquires a responsiveness parameter during change of output of the sensor between rich and lean peaks; and a abnormality determination portion that when the number of acquisitions reaches or exceeds a first set number, the presence/absence of sensor abnormality based on the average value and the criterion-value is determined, if the average value is not in a pending region; however, if the average value is in the pending region, the data acquisition is performed until the number of acquisitions performed during a large-amount-of-intake-air state of the engine reaches a second set number, and the presence/absence of sensor abnormality based on the average value of the data acquired by the second set number of acquisitions and the criterion-value is determined.

An apparatus includes: an control portion that controls fluctuating the air/fuel ratio; a data acquisition portion that acquires a responsiveness parameter during change of output of the sensor between a rich peak to a lean peak; and a determination portion that determines presence/absence of abnormality of the sensor based on an abnormality criterion value and a data average. When the number of the acquired data becomes equal to or greater than a first number, if the number of the acquired data during a large intake-air-amount of an engine is greater than or equal to a second number, the determination portion determines the presence/absence of abnormality, or if the number of the acquired data during the large intake-air-amount is less than the second number, the determination portion does not determines that, but acquires the data until the number of the acquired data during the large intake-air-amount reaches the second number.

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Toyota, Japan

Keiko Okamoto