Abnormality diagnosing system for air/fuel ratio feedback control system

An air/fuel ratio controller comprising:

• an air/fuel ratio sensor for generating a signal representative of a detected air/fuel ratio of an internal combustion engine;
• air/fuel ratio correction coefficient generating means for generating an air/fuel ratio correction coefficient according to a difference between the detected air/fuel ratio and a target air/fuel ratio;
• air/fuel ratio control means for controlling an amount of fuel to be supplied to the engine using the air/fuel ratio correction coefficient set by the air/fuel ratio correction coefficient generating means;
• sensor diagnostic means for checking an abnormality of the air/fuel ratio sensor based on behavior of the detected air/fuel ratio and behavior of the air/fuel ratio correction coefficient,
• first amplitude calculating means for calculating an amplitude of the air/fuel ratio detected by the air/fuel ratio sensor;
• and
• second amplitude calculating means for calculating an amplitude of the air/fuel ratio correction coefficient set by the air/fuel ratio correction coefficient generating means;
• wherein the sensor diagnostic means is for checking for an abnormality of the air/fuel ratio sensor based on a comparison between the amplitude of the air/fuel ratio calculated by the first amplitude calculating means and the amplitude of the air/fuel ratio correction coefficient calculated by the second amplitude calculating means.

An air/fuel ratio controller comprising:

• an air/fuel ratio sensor for generating a signal representative of a detected air/fuel ratio of an internal combustion engine;
• air/fuel ratio correction coefficient generating means for generating an air/fuel ratio correction coefficient according to a difference between the detected air/fuel ratio and a target air/fuel ratio;
• air/fuel ratio control means for controlling an amount of fuel to be supplied to the engine using the air/fuel ratio correction coefficient set bv the air/fuel ratio correction coefficient generating means;
• sensor diagnostic means for checking an abnormality of the air/fuel ratio sensor based on behavior of the detected air/fuel ratio and behavior of the air/fuel ratio correction coefficient,
• phase difference calculating means for calculating a phase difference between a phase of the air/fuel ratio detected by the air/fuel ratio sensor and a phase of the air/fuel ratio correction coefficient set by the air/fuel ratio correction coefficient generating means;
• wherein the sensor diagnostic means is for checking for abnormality of the air/fuel ratio sensor based on the phase difference calculated by the phase difference calculating means.

An air/fuel ratio controller comprising:

• an air/fuel ratio sensor for generating a signal representative of a detected air/fuel ratio of an internal combustion engine;
• air/fuel ratio correction coefficient generating means for generating an air/fuel ratio correction coefficient according to a difference between the detected air/fuel ratio and a target air/fuel ratio;
• air/fuel ratio control means for controlling an amount of fuel to be supplied to the engine using the air/fuel ratio correction coefficient set bv the air/fuel ratio correction coefficient generating means;
• sensor diagnostic means for checking an abnormality of the air/fuel ratio sensor based on behavior of the detected air/fuel ratio and behavior of the air/fuel ratio correction coefficient,
• first difference accumulating means for accumulating differences between the air/fuel ratio detected by the air/fuel ratio sensor and the target air/fuel ratio;
• and
• second difference accumulating means for accumulating differences between the air/fuel ratio correction coefficient set by the air/fuel ratio correction coefficient generating means and a reference value of the air/fuel ratio correction coefficient;
• wherein the sensor diagnostic means is for checking for an abnormality of the air/fuel ratio sensor based on comparison between differences accumulated by the first difference accumulating means and differences accumulated by the second difference accumulating means.

An air/fuel ratio controller comprising:

• an air/fuel ratio sensor for generating a signal representative of a detected air/fuel ratio of an internal combustion engine;
• air/fuel ratio correction coefficient generating means for generating an air/fuel ratio correction coefficient according to a difference between the detected air/fuel ratio and a target air/fuel ratio;
• air/fuel ratio control means for controlling an amount of fuel to be supplied to the engine using the air/fuel ratio correction coefficient set bv the air/fuel ratio correction coefficient generating means;
• sensor diagnostic means for checking an abnormality of the air/fuel ratio sensor based on behavior of the detected air/fuel ratio and behavior of the air/fuel ratio correction coefficient,
• air/fuel ratio change calculating means for calculating a change rate of the detected air/fuel ratio;
• and
• correction coefficient change calculating means for calculating a change rate of the air/fuel ratio correction coefficient;
• wherein the sensor diagnostic means includes abnormality diagnosing means for diagnosing an abnormality of the air/fuel ratio sensor based on the air/fuel ratio change rate and the correction coefficient change rate.

An air/fuel ratio controller comprising:

• an air/fuel ratio sensor for generating a signal representative of a detected air/fuel ratio of an internal combustion engine;
• air/fuel ratio correction coefficient generating means for generating an air/fuel ratio correction coefficient according to a difference between the detected air/fuel ratio and a target air/fuel ratio;
• air/fuel ratio control means for controlling an amount of fuel to be supplied to the engine using the air/fuel ratio correction coefficient set by the air/fuel ratio correction coefficient generating means;
• sensor diagnostic means for checking an abnormality of the air/fuel ratio sensor based on behavior of the detected air/fuel ratio and behavior of the air/fuel ratio correction coefficient,
• first element calculating means for calculating a first abnormality deciding element based on the detected air/fuel ratio;
• and
• second element calculating means for calculating a second abnormality deciding element based on the air/fuel ratio correction coefficient;
• wherein the sensor diagnostic means includes abnormalilty diagnosing means for diagnosing an abnormality of the air/fuel ratio feedback control system in accordance with a plurality of normality/abnormality deciding regions, as individually defined by at least one threshold value, by correlating the first and second abnormality deciding elements with the normality/abnormality deciding regions.

An air/fuel ratio controller comprising:

• an air/fuel ratio sensor which can vary its output linearly when detecting an air/fuel ratio in an internal combustion engine;
• air/fuel ratio correction coefficient generating means for generating an air/fuel ratio correction coefficient in accordance with a difference between the air/fuel ratio detected by the air/fuel ratio sensor and a target air/fuel ratio;
• air/fuel ratio control means for controlling amount of fuel to be supplied to the engine by using the air/fuel ratio correction coefficient set by the air/fuel ratio correction coefficient generating means;
• air/fuel ratio period calculating means for calculating an oscillation period of the air/fuel ratio detected by the air/fuel ratio sensor;
• and
• sensor diagnostic means for checking for an abnormality of the air/fuel ratio sensor based on the oscillation period of the air/fuel ratio.

An air/fuel ratio controller comprising:

• an air/fuel ratio sensor which can vary its output linearly when detecting an air/fuel ratio in an internal combustion engine;
• air/fuel ratio correction coefficient generating means for generating an air/fuel ratio correction coefficient in accordance with a difference between the air/fuel ratio detected by the air/fuel ratio sensor and a target air/fuel ratio;
• air/fuel ratio control means for controlling an amount of fuel to be supplied to the engine by using the air/fuel ratio correction coefficient set by the air/fuel ratio correction coefficient generating means;
• correction coefficient period calculating means for calculating an oscillation period of the air/fuel ratio correction coefficient set by the air/fuel ratio correction coefficient generating means;
• and
• sensor diagnostic means for checking for an abnormality of the air/fuel ratio sensor based on the oscillation period of the air/fuel ratio correction coefficient.