Patent ID: 9354191
Filing Date: 2016-05-31
CPC Classification: G01N

Claim Text:
1. An oxygen sensor controlling apparatus that controls an oxygen sensor that includes: a detection element made of a solid electrolyte and having a pair of electrodes; and a heater configured to heat the detection element, in which the oxygen sensor has a characteristic that a sensor output with respect to an air-fuel ratio is changed between a rich state and a lean state with a theoretical air-fuel ratio being a boundary in response to an oxygen concentration in an exhaust gas of an internal-combustion engine, the oxygen sensor controlling apparatus comprising: a controller configured to: obtain a degradation index that indicates a value according to a degree of degradation of the detection element; obtain the sensor output from the oxygen sensor; detect an internal resistance of the detection element by causing a temporary change with respect to one of a voltage between the electrodes of the detection element and an electric current that flows between the electrodes; successively obtain a target resistance value corresponding to the internal resistance using the degradation index and a first sensor output that is a value of the sensor output obtained at a time before or after a period when the temporary change occurs; and feedback-control energization of the heater so that the internal resistance becomes the target resistance value, wherein the controller is further configured to: obtain a reference resistance value corresponding to the degradation index; and correct the reference resistance value using a correction function that uses the first sensor output as a variable, to obtain the target resistance value, and wherein the correction function is a composite function of: a first correction function that regulates a case where the first sensor output is on a lean side with reference to a predetermined threshold output, with respect to the air-fuel ratio; and a second correction function that regulates a case where the first sensor output is on a rich side with reference to the predetermined threshold output, with respect to the air-fuel ratio.