Nissan Motor Company Limited

Kaname Naganuma

Hiroyuki Itoyama

Hirofumi Tsuchida

Akira Tayama

Toshikazu Shiino

An upstream catalyst ( ) which stores oxygen in exhaust gas and releases the stored oxygen for oxidizing a reducing agent component contained in the exhaust gas, and a downstream catalyst ( ) which stores nitrogen oxides in the exhaust gas and releases the stored nitrogen oxides by reducing the stored nitrogen oxides by the reducing agent component contained in the exhaust gas, are provided in an exhaust passage ( ) of an engine ( ). When the storage amount of nitrogen oxides of the downstream catalyst ( ) reaches a predetermined value, additional fuel is injected from a fuel injector ( ) after combustion, and stored oxygen in the upstream catalyst ( ) is released by the reducing agent components in the additional fuel. After release of oxygen, the supply of the additional fuel is stopped and the supply of the main fuel is increased.

Engine exhaust emission control

An integrated internal combustion engine control system in combination with an automotive emission control system, comprises an exhaust-gas recirculation valve (EGR valve) employed in an EGR system. A target EGR amount is calculated as a function of an intake-air flow rate measured by an air-flow meter and a target EGR rate based on engine operating conditions such as engine speed and engine load. The opening of the EGR valve is adjusted by a command from a control unit so that the target EGR amount is attained. The target EGR rate is preferably calculated depending on an intake pressure as well as the engine speed and the engine load. In combination with the above-mentioned EGR control, a throttle valve disposed in the induction system is effectively controlled in response to an actual valve lift of the EGR valve and a differential pressure between an exhaust pressure and the intake pressure. A fuel-injection amount is accurately controlled in consideration of a variation of an excess-air factor. To compensate a phase lag a predetermined advance processing is made to a signal from a typical air-flow meter, and then the advance-processed signal is effectively signal-processed to invert a reverse-flow component in the output signal.

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Yokosuka, Japan

Kaname Naganuma