Abstract: Control device of an internal combustion engine that determines whether or not to perform sensor element heating control of an air-fuel ratio sensor with high accuracy based on the mass of condensed water in an exhaust pipe. The control device computes the rate of change of condensed water mass in an exhaust pipe based on the saturated water vapor pressure and the water vapor partial pressure of exhaust gas, and computes the rate of change of evaporation mass in the exhaust pipe based on the amount of heat which the condensed water receives in the exhaust pipe. The control device updates the mass of condensed water based on the rate of change of condensed water mass and the rate of change of evaporation mass, and determines whether or not to perform heating control by a heating controlling unit based on the updated mass of condensed water.

Abstract: Control device of an internal combustion engine that determines whether or not to perform sensor element heating control of an air-fuel ratio sensor with high accuracy based on the mass of condensed water in an exhaust pipe. The control device computes the rate of change of condensed water mass in an exhaust pipe based on the saturated water vapor pressure and the water vapor partial pressure of exhaust gas, and computes the rate of change of evaporation mass in the exhaust pipe based on the amount of heat which the condensed water receives in the exhaust pipe. The control device updates the mass of condensed water based on the rate of change of condensed water mass and the rate of change of evaporation mass, and determines whether or not to perform heating control by a heating controlling unit based on the updated mass of condensed water.

Abstract: Disclosed is a diagnostic control apparatus for internal combustion engines capable of accurately diagnosing the presence and extent of air/fuel ratio variations in engine cylinders, even when the system has no part for detecting the air/fuel ratio in each cylinder. The diagnostic control apparatus measures the time required for the crankshaft to rotate to a specified angle for each cylinder; and based on this measured, required time, derives the 0.5 order component as the rotation fluctuation component for each two rotations of the crankshaft per each cylinder or the 1.0 order component as the rotation fluctuation component for each single rotation of the crankshaft; and also counts the number of times the 0.5 order component or 1.0 order component deviates from the preset range in the period set for each cylinder, and diagnoses an error in the output or in the air/fuel ratio for a particular cylinder when that count value exceeds a specified value.

Abstract: Disclosed is a diagnostic control apparatus for internal combustion engines capable of accurately diagnosing the presence and extent of air/fuel ratio variations in engine cylinders, even when the system has no part for detecting the air/fuel ratio in each cylinder. The diagnostic control apparatus measures the time required for the crankshaft to rotate to a specified angle for each cylinder; and based on this measured, required time, derives the 0.5 order component as the rotation fluctuation component for each two rotations of the crankshaft per each cylinder or the 1.0 order component as the rotation fluctuation component for each single rotation of the crankshaft; and also counts the number of times the 0.5 order component or 1.0 order component deviates from the preset range in the period set for each cylinder, and diagnoses an error in the output or in the air/fuel ratio for a particular cylinder when that count value exceeds a specified value.