Patent application number | Description | Published |
20110271665 | AIR-FUEL RATIO IMBALANCE AMONG CYLINDERS DETERMINING APPARATUS FOR AN INTERNAL COMBUSTION ENGINE - An air-fuel ratio imbalance among cylinders determining apparatus (a determining apparatus) according to an aspect of the present invention, obtains a parameter X for imbalance determination which becomes larger as a variation of an air-fuel ratio of an exhaust gas passing through a position at which the air-fuel ratio sensor is disposed becomes larger, based on an output value Vabyfs of an air-fuel ratio sensor | 11-10-2011 |
20120029792 | FUEL INJECTION AMOUNT CONTROL SYSTEM AND FUEL INJECTION AMOUNT CONTROL DEVICE FOR MULTI-CYLINDER INTERNAL COMBUSTION ENGINE - A fuel injection amount control system corrects the amount of fuel injected from each fuel injection valve in a feedback manner, based on an output value of an upstream air-fuel ratio sensor, so that the air-fuel ratio of exhaust gas flowing into a three-way catalyst coincides with a target air-fuel ratio. Also, the control system performs a high-pass filtering operation on the output value of the upstream air-fuel ratio sensor, so as to obtain a post-high-pass-filtering output value by removing a component that varies with variations in the center air-fuel ratio of the engine, from the output value of the upstream air-fuel ratio sensor. Then, the control system acquires an air-fuel ratio imbalance index value that increases as the degree of ununiformity in the air-fuel ratio among cylinders is larger, based on the post-high-pass-filtering output value. | 02-02-2012 |
20120185156 | APPARATUS FOR DETERMINING AN AIR-FUEL RATIO IMBALANCE AMONG CYLINDERS OF AN INTERNAL COMBUSTION ENGINE - An apparatus for determining an air-fuel ratio imbalance among cylinders based on an output value of an air-fuel ratio sensor, an imbalance determination parameter which becomes larger or smaller as a difference among air-fuel ratios becomes larger, and performs determining an air-fuel ratio imbalance among cylinders based on a result of a comparison between the imbalance determination parameter and a imbalance determination threshold. The determining apparatus calculates a purge correction coefficient which compensates for a change in the air-fuel ratio due to an evaporated fuel gas which is generated in a fuel tank, while the evaporated fuel gas is being introduced into an intake passage, and corrects a fuel injection amount with the purge correction coefficient FPG. | 07-19-2012 |
20120209498 | AIR-FUEL-RATIO IMBALANCE DETERMINATION APPARATUS FOR INTERNAL COMBUSTION ENGINE - An inter-cylinder air-fuel-ratio imbalance determination apparatus includes an air-fuel-ratio sensor in an exhaust passage of an engine. The air-fuel-ratio sensor functions as a limiting-current-type wide range air-fuel-ratio sensor when a voltage is applied, and functions as a concentration-cell-type oxygen concentration sensor when no voltage is applied. The determination apparatus causes the air-fuel-ratio sensor to function as the limiting-current-type wide range air-fuel-ratio sensor, and executes air-fuel ratio feedback control on the basis of the output value of the air-fuel-ratio sensor. When an imbalance determination parameter is obtained, the determination apparatus causes the air-fuel-ratio sensor to function as the concentration-cell-type oxygen concentration sensor, and obtains, as the imbalance determination parameter, a value corresponding to the differentiated value of the output value of the air-fuel-ratio sensor. The determination apparatus determines an inter-cylinder air-fuel-ratio imbalance state, when the absolute value of the imbalance determination parameter is greater than an imbalance determination threshold value. | 08-16-2012 |
20120232773 | INTER-CYLINDER AIR-FUEL RATIO IMBALANCE DETERMINATION APPARATUS FOR AN INTERNAL COMBUSTION ENGINE - An inter-cylinder air-fuel ratio imbalance determination apparatus (determination apparatus) according to the present invention obtains, based on the output value of the air-fuel ratio sensor | 09-13-2012 |
20130073184 | INTER-CYLINDER AIR-FUEL RATIO IMBALANCE DETERMINING APPARATUS FOR INTERNAL COMBUSTION ENGINE - An inter-cylinder air-fuel ratio imbalance determining apparatus for an internal combustion engine includes an air-fuel ratio sensor; fuel injection valves; an instructed fuel injection amount control unit; and an imbalance determination unit configured: to acquire a time-differential-value corresponding value that is an amount of change per predetermined time in an output value of the sensor or a detected air-fuel ratio represented by the output value; to acquire a positive gradient corresponding value based on a positive value of the time-differential-value corresponding value; to acquire a negative gradient corresponding value based on a negative value of the time-differential-value corresponding value; to determine an imbalance determination threshold based on a magnitude of a ratio of the negative gradient corresponding value to the positive gradient corresponding value; and to determine whether inter-cylinder air-fuel ratio imbalance has occurred by comparing a magnitude of the negative gradient corresponding value with the imbalance determination threshold. | 03-21-2013 |
20130253802 | INTER-CYLINDER AIR-FUEL RATIO IMBALANCE DETECTION APPARATUS FOR INTERNAL COMBUSTION ENGINE - An air-fuel ratio imbalance detection apparatus includes an air-fuel ratio sensor that is arranged in an exhaust passage of an internal combustion engine and that includes an electrode and a diffusion layer provided on the electrode; an estimating unit configured to estimate or detect an output variation amount that is an amount of variation in an output of the air-fuel ratio sensor due to an influence of a pressure pulsation of exhaust gas from the internal combustion engine; and a determination unit configured to determine whether there is an air-fuel ratio imbalance among cylinders of the internal combustion engine, on the basis of the output variation amount and a determination value based on the output of the air-fuel ratio sensor. | 09-26-2013 |
20140156205 | INTER-CYLINDER AIR-FUEL RATIO VARIATION ABNORMALITY DETECTION APPARATUS FOR MULTICYLINDER INTERNAL COMBUSTION ENGINE - A first parameter correlated with a degree of a variation in the output from the air-fuel ratio sensor is calculated. A possible range of a second parameter representing a degree of a variation in air-fuel ratio among the cylinders is determined based on the first parameter. The first parameter is calculated with an air-fuel ratio of a predetermined cylinder forcibly changed. A difference between the unchanged first parameter and the forcibly changed first parameter is determined. A first characteristic representing a relation between the second parameter and the difference is determined based on the possible range of the second parameter and the difference. One of the determination value and the first parameter calculated before the forced change is corrected based on inclination of the determined first characteristic. | 06-05-2014 |
20140283801 | INTER-CYLINDER AIR-FUEL RATIO VARIATION ABNORMALITY DETECTION APPARATUS FOR MULTICYLINDER INTERNAL COMBUSTION ENGINE - A first parameter correlated with a degree of fluctuation of output from an air-fuel ratio sensor is calculated, and whether or not the calculated first parameter has a value between a predetermined primary determination upper-limit value α1H and a primary determination lower-limit value is determined. Such forced active control as reduces an air-fuel ratio shift in one of the cylinders which is subjected to a most significant air-fuel ratio shift is performed when the calculated first parameter is determined to have a value between the predetermined primary determination upper-limit value and the primary determination lower-limit value. A first parameter is calculated while the forced active control is in execution. The calculated first parameter is compared with a predetermined secondary determination value to determine whether or not variation abnormality is present. | 09-25-2014 |
20140309907 | INTER-CYLINDER AIR-FUEL RATIO VARIATION ABNORMALITY DETECTION APPARATUS - When two abnormal cylinders are causing variation abnormality, these abnormal cylinders are identified. A parameter correlated with a degree of fluctuation of output from an air-fuel ratio sensor installed in an exhaust passage common to a plurality of cylinders is calculated. Based on the calculated parameter, inter-cylinder air-fuel ratio variation abnormality is detected. The following steps are carried out: (A) a step of forcibly changing amounts of fuel injected for two of the plurality of cylinders and calculating the parameter, (B) a step of changing the two cylinders to other two cylinders and repeating the step (A), and (C) a step of identifying two cylinders causing variation abnormality based on a plurality of the parameters calculated in the steps (A) and (B). | 10-16-2014 |