Patent application number | Description | Published |
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 |
20140298889 | APPARATUS FOR DETECTING VARIATION ABNORMALITY IN AIR-FUEL RATIO BETWEEN CYLINDERS - An apparatus for detecting a variation abnormality in an air-fuel ratio between cylinders according to the present invention is configured to calculate a value representing a change in an air-fuel ratio based on an output of an air-fuel ratio sensor that is provided in an exhaust passage in a predetermined operating state in which fuel is injected from a fuel injection valve, perform, to the calculated value, sensitivity correction in accordance with a sensitivity of the sensor based on the output of the sensor during fuel-cut operation and outside atmospheric pressure correction based on outside atmospheric pressure, and determine the presence or absence of a variation abnormality in an air-fuel ratio between cylinders by comparing the corrected value with a predetermined value. | 10-09-2014 |
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 |
20150114376 | INTER-CYLINDER AIR-FUEL RATIO VARIATION ABNORMALITY DETECTION APPARATUS - An apparatus according to the present invention includes a control apparatus configured to detect inter-cylinder air-fuel ratio variation abnormality based on a parameter correlated with the degree of a fluctuation in output from the air-fuel ratio sensor. The control apparatus is configured to execute a step of identifying two cylinders estimated to have a deviation of the air-fuel ratio based on an output waveform from the air-fuel ratio sensor during one engine cycle, a step of performing reducing control to reduce the deviation of the air-fuel ratio on each of the two cylinders, that is, a first cylinder and a second cylinder, to calculate first and second values of the parameter, respectively, and a step of identifying one of the two cylinders having the most significant deviation of the air-fuel ratio based on the first and second values. | 04-30-2015 |
20160069242 | ABNORMALITY DIAGNOSIS SYSTEM OF AIR-FUEL RATIO SENSOR - An air-fuel ratio sensor is provided in an exhaust passage of an internal combustion engine which can perform fuel cut control, and detects an air-fuel ratio of exhaust gas. The system calculates the response time of the air-fuel ratio sensor based on a changing output value of the air-fuel ratio sensor while performing or after fuel cut control, and compares the calculated response time and a threshold value to diagnose an abnormality. The abnormality diagnosis system is configured to correct the response time so that the response of the air-fuel ratio sensor is treated as becoming faster, the smaller the lean degree of the air-fuel ratio corresponding to the converged value of the air-fuel ratio sensor during fuel cut control; and diagnose an abnormality in the response of the air-fuel ratio sensor based on the corrected calculated response time and threshold value. | 03-10-2016 |