Nissan Motor Company Limited

Rie Takatsuto

Hiroshi Katoh

Masato Kobayashi

Hideaki Kobayashi

A diagnostic apparatus for an internal combustion engine. An exhaust purification section includes an exhaust purifier disposed in an exhaust passage of the internal combustion engine, for purifying an exhaust emission, and a purifier activation section configured to control engine operating parameters of the internal combustion engine to promote activation of the exhaust purifier during the internal combustion engine being cold. The diagnostic apparatus is configured to determine a state of the exhaust purifier, to determine a total purifier out emission quantity as a quantity of the exhaust emission exiting the exhaust purifier during the internal combustion engine being cold, in accordance with the state of the exhaust purifier, and to determine normality of the exhaust purification section in accordance with the total purifier out emission quantity.

Diagnostic apparatus for internal combustion engine

A diagnostic apparatus for an internal combustion engine is disclosed herein. In one embodiment, the diagnostic apparatus comprises a catalytic converter and a controller. The catalytic converter is disposed in an exhaust passage of an engine and treats an exhaust gas component in the exhaust gas. The controller is adapted to perform a number of functions. More specifically, the controller is adapted to operate the engine with an engine control parameter to increase catalyst temperature of the catalytic converter during a cold engine condition. The controller is further adapted to calculate a temperature factor indicative to temperature increase of the catalyst based on the engine control parameter. The controller is further adapted to estimate the amount of the exhaust gas component flowing out of the catalytic converter based on the temperature factor. Finally, in one embodiment, the controller is adapted to determine malfunction of the engine operation to increase catalyst temperature of the catalytic converter based on the amount of exhaust gas component flowing out of the catalytic converter. A diagnostic method is also disclosed.

Diagnostic apparatus and diagnostic method for an internal combustion engine

An air/fuel ratio sensor () and a three-way catalytic converter (A) having an oxygen storage function are provided in an exhaust passage () of an internal combustion engine (). A controller () runs the engine () under the alternating application of a stoichiometric air/fuel ratio and a rich air/fuel ratio, and a diagnosis of deterioration in the air/fuel ratio sensor () is performed on the basis of the amplitude of variation in the air/fuel ratio detected by the air/fuel ratio sensor (). By executing the diagnosis only immediately after a fuel cut, the amount of oxygen stored in the three-way catalytic converter (A) at the start point of the diagnosis is equal to the maximum amount. When the rich air/fuel ratio is applied, the converter (A) releases the stored oxygen to maintain the exhaust gas purification performance of the converter ().

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Yokohama, Japan

Rie Takatsuto