| Patent application number | Description | Published |
|---|
| 20090037079 | Air-fuel ratio control apparatus and method for an internal combustion engine - When an internal combustion engine including a plurality of cylinders is operating steadily, an index value relating to an actual hydrogen content in exhaust gas downstream of a portion where exhaust passages from the cylinders merge, and upstream of a catalyst is detected. When an index value relating to the actual hydrogen content in the exhaust gas is larger than a determination index value relating to a hydrogen content corresponding to a permissible limit of air-fuel ratio variation, it is determined that there is abnormal air-fuel ratio variation between the cylinders. | 02-05-2009 |
| 20090211350 | APPARATUS AND METHOD FOR DETECTING ABNORMALITY OF INTER-CYLINDER AIR-FUEL RATIO DISPERSION IN MULTI-CYLINDER INTERNAL COMBUSTION ENGINE - An apparatus or a method for detecting an abnormality of inter-cylinder air-fuel ratio dispersion in a multi-cylinder internal combustion engine according to the invention is equipped with a catalytic element that purifies exhaust gas of hydrogen, a first air-fuel ratio sensor that detects an air-fuel ratio of exhaust gas that has not passed through the catalytic element, a second air-fuel ratio sensor that detects an air-fuel ratio of exhaust gas that has passed through the catalytic element, a device that detects an abnormality of inter-cylinder air-fuel ratio dispersion on the basis of a divergence state of a detected value of a second air-fuel ratio to a lean side from a detected value of a first air-fuel ratio, and a device that forcibly reduces fuel injection amounts in cylinders individually when an abnormality on dispersion is detected by the abnormality detector, detects a divergence state of the detected value of the second air-fuel ratio to the lean side from the detected value of the first air-fuel ratio at this time, and specifies as an abnormal cylinder that one of the cylinders in which a value indicating this divergence state has become smaller than at a time of detection of the abnormality of dispersion. | 08-27-2009 |
| 20090260347 | APPARATUS AND METHOD FOR DETECTING ABNORMAL AIR-FUEL RATIO VARIATION AMONG CYLINDERS OF MULTI-CYLINDER INTERNAL COMBUSTION ENGINE - An apparatus and a method for detecting abnormal air-fuel ratio variation among cylinders of a multi-cylinder internal combustion engine are provided. The apparatus includes: a catalyst that is provided in an exhaust passage of the multi-cylinder internal combustion engine; a catalyst temperature detection unit that detects a temperature of the catalyst; a catalyst temperature estimation unit that estimates a temperature of the catalyst based on an engine operating state; and an abnormality detection unit that determines whether abnormal air-fuel ratio variation among the cylinders has occurred based on the detected temperature of the catalyst and the estimated temperature of the catalyst. | 10-22-2009 |
| 20100211290 | ABNORMALITY DIAGNOSTIC DEVICE AND ABNORMALITY DIAGNOSTIC METHOD FOR MULTICYLINDER INTERNAL COMBUSTION ENGINE - A fuel injection amount from fuel injection valves is actively controlled and an input air-fuel ratio is caused forcibly to oscillate. A system from the fuel injection valves to the air-fuel ratio sensor is simulated by a first order delay system, and a gain and time constant are identified on the basis of the input air-fuel ratio relating to the model and an output air-fuel ratio obtained from the air-fuel ratio sensor. The presence of an air-fuel ratio abnormal variation is diagnosed on the basis of whether or not the identified values of the gain and the time constant are less than a first and second predetermined values respectively. | 08-19-2010 |
| 20110054761 | CYLINDER-TO-CYLINDER AIR/FUEL RATIO IMBALANCE DETERMINATION SYSTEM OF INTERNAL COMBUSTION ENGINE - A cylinder-to-cylinder air/fuel ratio imbalance determination system obtains an imbalance determination parameter that increases or decreases as a difference between the air/fuel ratios of different cylinders increases, based on output values of an air/fuel ratio sensor, and makes a cylinder-to-cylinder A/F imbalance determination, based on the result of comparison between the imbalance determination parameter and a threshold value for imbalance determination. The determination system changes the amount of fuel injected into one or more of the cylinders so as to create a forced imbalance condition in which the air/fuel ratio of a particular cylinder deviates from the air/fuel ratio of the remaining cylinders, and obtains an air/fuel ratio sensor evaluation parameter (e.g., rate of change ΔAF of the detected air/fuel ratio) in this condition. Then, the determination system determines whether the air/fuel ratio sensor is adequate for making a cylinder-to-cylinder A/F imbalance determination, by comparing the evaluation parameter with a reference parameter (an evaluation parameter obtained based on output values of a reference air/fuel ratio sensor in the same forced imbalance condition). | 03-03-2011 |
