Abstract: A sensor for detecting oxygen concentration in exhaust gas or an air-fuel ratio provided with a solid electrolyte body, an exhaust gas side electrode being disposed on one side of the solid electrolyte body and being in contact with the exhaust gas, an atmosphere side electrode being disposed on the other side of the solid electrolyte body and being in contact with the atmosphere, and an electric circuit applying a reference voltage between these electrodes is arranged in an engine exhaust passage. The sensor for detecting the oxygen concentration in the exhaust gas or the air-fuel ratio has a characteristic in which an output current continues to increase without having a limiting current region when the voltage applied between the electrodes is increased while the air-fuel ratio is constant. The air-fuel ratio is controlled based on the output current of the sensor for detecting the oxygen concentration in the exhaust gas or the air-fuel ratio.

Abstract: A sensor characteristic correction device is configured to detect a characteristic of a first sensor arranged upstream of a catalyst 6 in an exhaust passage 4 of an internal combustion engine 2, and a characteristic of a second sensor that is an air-fuel sensor 12 arranged downstream of the catalyst 6, to calculate a first air-fuel ratio based on the characteristic of the first sensor, and calculates a second air-fuel ratio based on the characteristic of the second sensor, to detect, when the catalyst 6 is in an inactive state after start-up of the internal combustion engine 2, a difference between the first characteristic and the second characteristic or a difference between the first air-fuel ratio and the second air-fuel ratio, and to correct the responsiveness of the first or the second sensor in accordance with the difference.

Abstract: In an exhaust path of an internal combustion engine, a catalyst, a first air-fuel ratio sensor installed upstream thereof, and a second air-fuel ratio sensor installed downward thereof are disposed. An air-fuel ratio of the engine is controlled to a rich air-fuel ratio or a lean air-fuel ratio. In a state that is determined as a state where the catalyst stores oxygen to an upper limit after the air-fuel ratio is switched to the lean air-fuel ratio from the rich air-fuel ratio, or a state where the catalyst releases oxygen to a lower limit after the air-fuel ratio is switched to the rich air-fuel ratio from the lean air-fuel ratio, a first output from the first air-fuel ratio sensor, and a second output from the second air-fuel ratio sensor are detected and based on a difference therebetween the output of the first air-fuel ratio sensor is corrected.

Abstract: A control system having an exhaust gas sensor having a solid electrolyte layer, a first electrode layer arranged on one surface of the solid electrolyte layer and exposed to exhaust gas through a diffusion-controlling layer and/or trap layer, and a second electrode layer arranged on the other surface of the solid electrolyte layer, wherein the solid electrolyte layer comprises a self-healing ceramic material and/or the diffusion-controlling layer and/or trap layer comprise a self-healing ceramic material; and a voltage applying device; wherein periodically and/or when it is judged that the layer comprising the self-healing ceramic material is damaged, regeneration treatment comprising changing the voltage applied between the first electrode layer and the second electrode layer by the voltage applying device is performed so that the amount of oxygen flowing through the layer comprising the self-healing ceramic material is larger than normal.

Abstract: A catalyst deterioration determination system for determining deterioration of an exhaust gas purification catalyst having a capability of storing oxygen determines deterioration of the exhaust gas purification catalyst on the basis of its oxygen storage capacity. The system includes an oxygen concentration sensor provided downstream of the catalyst and having characteristics by which as rich gas components in exhaust gas increase, the oxygen concentration sensor outputs a measurement value of the oxygen concentration corresponding to a richer air-fuel ratio. When determining deterioration, the system performs a rich shift mode in which the exhaust gas air-fuel ratio is shifted from a lean air-fuel ratio to a rich air-fuel ratio and a lean shift mode in which the exhaust gas air-fuel ratio is shifted from a rich air-fuel ratio to a lean air-fuel ratio by exhaust gas air-fuel ratio control means, based on the measurement value of the oxygen concentration sensor.

Abstract: This invention relates to an air-fuel ratio control device of an internal combustion engine, and an object of the invention is to provide an air-fuel ratio control device of an internal combustion engine that is capable of suppressing a deterioration in the controllability of air-fuel ratio feedback control after restarting an engine. FIG. 6 illustrates an elapsed time after engine startup, and output values of a front A/F sensor 16 and a rear A/F sensor 18. As shown in FIG. 6, the output values of the front A/F sensor 16 and rear A/F sensor 18 become equal from a time T3 onwards. Hence, by switching to normal air-fuel ratio feedback control at the time T3, highly accurate air-fuel ratio feedback control that is in accordance with the actual situation is enabled.

Abstract: An oxygen amount (an oxygen storage amount OSA) stored by metal cerium during a storage cycle is obtained based on an output value of an A/F sensor in a time period immediately before an exhaust air-fuel ratio (a downstream side A/F) detected by the A/F sensor shifts to a lean region, and degradation relating to OSC of the three-way catalyst is detected. In the storage cycle, a target air-fuel ratio is set so that an air-fuel ratio of exhaust emission flowing into an S/C changes from rich to lean. Therefore, the downstream side A/F shifts from stoichiometry to the lean region at a time after reaching stoichiometry. When the three-way catalyst degrades, the downstream side A/F shifts to the lean region from stoichiometry at a time. Therefore, the calculated oxygen storage amount OSA becomes extremely smaller as compared with that at a normal time.

Abstract: A correction device for an air/fuel ratio sensor in the present invention, the sensor issuing an output according to an air/fuel ratio and installed on the downstream from catalyst of the exhaust passage, has air/fuel ratio control means for controlling an air/fuel ratio of an exhaust gas on the upstream side from a catalyst to switch between a rich air/fuel ratio which is richer and a lean air/fuel ratio which is leaner than a stoichiometric air/fuel ratio. Moreover, correction means for correcting an output of the sensor in accordance with a difference between the output of the sensor during a predetermined period during air/fuel ratio control by the air/fuel ratio control means, and a reference output corresponding to a stoichiometric air/fuel ratio, is provided.

Abstract: A sensor characteristic correction device is configured to detect a characteristic of a first sensor arranged upstream of a catalyst 6 in an exhaust passage 4 of an internal combustion engine 2, and a characteristic of a second sensor that is an air-fuel sensor 12 arranged downstream of the catalyst 6, to calculate a first air-fuel ratio based on the characteristic of the first sensor, and calculates a second air-fuel ratio based on the characteristic of the second sensor, to detect, when the catalyst 6 is in an inactive state after start-up of the internal combustion engine 2, a difference between the first characteristic and the second characteristic or a difference between the first air-fuel ratio and the second air-fuel ratio, and to correct the responsiveness of the first or the second sensor in accordance with the difference.

Abstract: In this invention, an EMF oxygen sensor is subjected to an activation process applying unidirectional voltage between an atmosphere electrode and an exhaust electrode thereof. A control device controlling the oxygen sensor in which a voltage was applied with the atmosphere electrode being positive, additionally applies unidirectional voltage between the electrodes to make the atmosphere electrode positive, for example, when the oxygen sensor was used under an environment in which the air-fuel ratio of the internal combustion engine was rich relative to the theoretical air-fuel ratio. Conversely, A control device controlling the oxygen sensor in which a voltage was applied to make the atmosphere electrode negative, additionally applies unidirectional voltage between the electrodes to make the atmosphere electrode negative, for example, when the oxygen sensor was used under an environment in which the air-fuel ratio was lean relative to the theoretical air-fuel ratio.

Abstract: An internal combustion engine control device and a control method therefore in which feedback control is performed such that a detected air-fuel ratio of exhaust gas detected on the basis of a critical electric current flowing in a solid electrolyte layer of an air-fuel ratio sensor when an air-fuel ratio detection voltage is applied between an exhaust-side electrode layer and an atmosphere-side electrode layer of the sensor matches a stoichiometric air-fuel ratio. When a parameter acquired as an imbalance determination parameter is larger than an imbalance determination threshold, an air-fuel ratio inter-cylinder imbalance state is determined to have occurred.