Internal combustion engine control device

An internal combustion engine control device that controls an internal combustion engine including a catalyst disposed in an exhaust pipe, a first exhaust gas sensor disposed on an upstream side of the catalyst, and a second exhaust gas sensor disposed on a downstream side of the catalyst, the internal combustion engine control device comprising:

• an oxygen storage ratio calculation unit which receives a catalytic reaction model having at least a detection value of the first exhaust gas sensor as an input and calculates an oxygen storage ratio of the catalyst;
• a statistical model calculation unit that uses a statistical model having the oxygen storage ratio as an input to predict a catalyst downstream exhaust gas concentration;
• and
• an air-fuel ratio correction amount calculation unit that receives a future catalyst downstream exhaust gas concentration calculated by the statistical model calculation unit and calculates an air-fuel ratio correction amount of an air-fuel mixture of the internal combustion engine, wherein
• a hysteresis term reflecting a characteristic in which a response speed of the output is different between when the input increases and when the input decreases is set to an input element of the statistical model,
• the hysteresis term includes a term defined by a first input parameter that takes both a positive value and a negative value, and a second input parameter defined by a product of an output parameter that takes a positive value and an absolute value of the first input parameter, and
• an air-fuel ratio is corrected in accordance with the air-fuel ratio correction amount to thereby increase a purification efficiency of the catalyst.