Mitsubishi Jidosha Kogyo Kabushiki Kaisha

Mitsubishi Denki Kabushiki Kaisha

Kazutoshi Noma

Hitoshi Kamura

Toru Hashimoto

Takuya Matsumoto

Yoichi Kadota

Atsuyoshi Kojima

Yasuhisa Yoshida

Koichi Namiki

A fuel control system for a cylinder injection type internal combustion engine which allows the fuel injection mode to make transition from a compression-stroke injection mode for realizing a high air-fuel ratio to the suction-stroke injection mode for realizing a low air-fuel ratio while ensuring stable combustion state without need for additional provision of any especial devices. The system includes an intake air flow sensor for detecting an intake air flow, a crank angle sensor for detecting rotation speed or rpm of the engine and a crank angle, a fuel injector for injecting fuel directly into each of cylinders of the engine, an exhaust gas recirculation system for regulating quantity of exhaust gas recirculated from an exhaust passageway to an intake passageway of the engine, and an electronic control unit for arithmetically determining control quantities for the fuel injector and the exhaust gas recirculation system, respectively, on the basis of detection information derived from the outputs of the intake air flow sensor and the crank angle sensor, respectively. When the fuel injection mode of the internal combustion engine is changed over from the compression-stroke fuel injection mode to the suction-stroke fuel injection mode, the electronic control unit starts to control the exhaust gas recirculation in precedence to any other control required for the suction-stroke fuel injection mode.

Fuel control method and system for cylinder injection type internal

A method for determining a failure of an exhaust gas recalculation (EGR) apparatus in which a failure of the EGR apparatus is determined by determining whether a difference between an intake manifold pressure developed when an EGR valve is open and that developed when the EGR valve is closed falls within a specified range, the EGR valve being temporarily opened and closed while failure determination is being implemented. The failure determination is aborted so as to prevent erroneous determination, if a variation of the engine speed exceeds a specified value during the failure determination, or if a variation of the opening degree of an idling speed control (ISC) valve, disposed in a bypass passage installed in an intake passage of an engine in a manner bypassing a throttle valve, exceeds a specified value during the failure determination, or if a fuel control mode changes during the failure determination. Alternatively, to prevent erroneous determination, an intake manifold pressure difference is corrected in accordance with a variation of the engine speed or a variation of the ISC valve opening degree during the failure determination, or the ISC valve opening degree is fixed during the failure determination.

Method for determining a failure of an EGR apparatus

An alr-fuel ratio controller for-an internal-combustion engine is provided with front and rear O.sub.2 sensors respectively installed in the exhaust system on the upstream and downstream sides of an exhaust gas purifier. The controller corrects the air-fuel ratio in accordance with the result of the comparison between a detected value of the front O.sub.2 sensor and a first reference value, to thereby control the alr-fuel ratio to a desired value, and also corrects a value of a parameter related preferably to at least one of a correction amount or a correcting timing for the air-fuel ratio correction, e.g., the first reference value, in accordance with the deviation between a detected value of the rear O.sub.2 sensor and a second reference value. When the deviation is large in magnitude, the parameter value is corrected at a larger correction degree than that used when the deviation magnitude is small, to thereby nonlinearly correct the parameter value in accordance with the magnitude of the deviation, whereby optimized correction of the parameter value is achieved so as to prevent the degeneration of the exhaust gas performance caused by the deterioration of the front and rear O.sub.2 sensors or catalyst concerned.

Air-fuel ratio controller for an internal combustion engine

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Kusatsu, Japan

Kazutoshi Noma