Hitachi, Ltd.

Hitachi Car Engineering Co., Ltd.

Hitachi Automotive Engineering Co., Ltd.

Rogelio B Agustin

Toshio Ishii

Yutaka Takaku

Akihito Numata

Eisaku Fukuchi

Kazuya Kawano

Yuichi Kashimura

A diagnostic apparatus for exhaust gas clarification apparatus for internal combustion engine diagnoses the individual catalyst independently by an air/fuel ratio sensor mounted before and after the individual catalyst. The individual catalyst is diagnosed by estimating the correlation of the output signals from the air/fuel ratio sensors mounted before and after the individual catalyst. The individual diagnosis operation is performed at distinctive operation regions adequate for their corresponding diagnostic mode. A by-pass route is provided for by-passing the exhaust gas from the upstream catalyst, and a by-pass valve switches the exhaust gas flow into the upstream catalyst or into the by-pass routes. A cross-correlation function calculation valve based upon outputs from air/fuel ratio sensors permits diagnosis of degradation of the overall catalyst.

Diagnostic apparatus for exhaust gas clarification apparatus for

A diagnosing system of a catalytic converter in an internal combustion engine has a detecting unit to detect an operating state of the engine and an air/fuel ratio control unit to adjust a fuel injection amount so as to keep an air/fuel ratio of a mixture that is inhaled into the engine to a target value. The operating state of the engine is detected, whereby it is confirmed that the engine lies in a predetermined operating region to execute a catalyst diagnosis on the basis of the detected operating state. In each of a plurality of different catalyst diagnosis regions, the performance of the catalytic converter or the performance of the catalytic converter array is diagnosed on the basis of the output signal of the first exhaust gas component sensor arranged on the upstream side of the catalytic converter array and the output signal of the second exhaust gas component sensor arranged on the downstream side.

Diagnosing system and method of catalytic converter for controlling

A diagnostic apparatus for exhaust gas clarification apparatus for internal combustion engine is disclosed. The diagnostic apparatus can diagnoses the individual catalyst independently by means that an air/fuel ratio sensor is mounted before and after the individual catalyst, and that the individual catalyst is diagnosed by estimating the correlation of the output signals from the air/fuel ratio sensors mounted before and after the individual catalyst, and furthermore, that the individual diangosis operation is performed at distinctive operation regions adequate for their corresponding diagnostic mode.

A malfunction monitoring apparatus for a secondary air supply system of an internal combustion engine includes an air flow sensor for measuring the flow rate of an air flowing into an intake air path of the engine, a secondary air introducing path disposed in the intake air path on the downstream side of a measuring position of the air flow rate for taking in a part of the air through the intake air path as a secondary air, a secondary air supply device for supplying the secondary air to an exhaust gas path, and a control unit. The apparatus may further include a pressure sensor for detecting the internal pressure of an intake manifold. The control unit determines a secondary air flow rate from a difference between a first air flow rate measured by the air flow sensor when the secondary air is not being supplied from the secondary air introducing path to the exhaust gas path and a second air flow rate measured by the air flow sensor when the secondary air is being supplied, or a difference between an intake air flow rate of the engine determined on the basis of the internal pressure of the intake manifold detected by the pressure sensor and an air flow rate measured by the air flow sensor when the secondary air is being supplied. In the case where the determined secondary air flow rate is out of a predetermined allowable range, the secondary air supply device is judged as being abnormal.

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Hitachinaka, Japan

Rogelio B Agustin