Abstract: The present invention is an operation control method on the basis of an ion current in an internal combustion engine, the method comprising a step of detecting the ion current generated within a combustion chamber 30 so as to control an operating state of the internal combustion engine 100 on the basis of a state of the detected ion current, wherein a control at an engine start point in time on the basis of the state of the ion current is stopped for predetermined cycles just after the engine start.

Abstract: In a method for determining an air fuel ratio of an internal combustion engine on the basis of an ion current, for detecting an ion current generated per ignition within a combustion chamber of the internal combustion engine, the method measures a generation period in which the ion current is greater than a determination value set as long as the ion current is generated, computes a divisor for computing a rate of fluctuation of the generation period of the ion current on the basis of a plurality of measured generation periods, computes the rate of fluctuation of the generation period of the ion current by weighing in a direction of increasing the computed divisor, and determines that an air fuel ratio is excessively high in the case that the calculated rate of fluctuation is equal to or more than a predetermined value.

Abstract: The present invention is an operation control method on the basis of an ion current in an internal combustion engine, the method comprising a step of detecting the ion current generated within a combustion chamber 30 so as to control an operating state of the internal combustion engine 100 on the basis of a state of the detected ion current, wherein a control at an engine start point in time on the basis of the state of the ion current is stopped for predetermined cycles just after the engine start.

Abstract: The invention relates of a method for determining a combustion state of an internal combustion engine, for detecting an ion current generated within a combustion chamber of the internal combustion engine, including the steps of measuring a characteristic value of the ion current detected during a period that the ion current is generated and a generation period in which the ion current is generated, and determining a combustion state on the basis of a relation between the characteristic value and the generation period with respect to an elapsed time from an ignition, and the method comprises determining that the combustion state is normal, by setting a determination reference to be larger with respect to the characteristic value and shorter with respect to the generation period, in the case that the elapsed time from the ignition is short, and determining that the combustion is normal, by setting the determination reference to be smaller with respect to the characteristic value and longer with respect to the g

Abstract: A diagnosis device for an exhaust gas recycling device diagnoses whether or not an exhaust gas recycling device is operating normally; the temperature of an exhaust gas recycling passage is detected by a temperature detection means, a decision is made by an exhaust gas recycling operating region detection means whether or not the operating region is such as to carry out exhaust gas recycling, when a decision is made that the operating region is such as to carry out exhaust gas recycling a counter is incremented and when otherwise is decremented, and a decision that the exhaust gas recycling is not being carried out normally, that is that the exhaust gas recycling device has failed, is made when the count value of this counter is at least a certain value and the temperature of the exhaust gas recycling passage is not more than a certain value.