Internal-combustion engine control device and filter regeneration method

An internal-combustion engine control device for an internal-combustion engine fueled by gasoline and including a filter that traps particulate matter in exhaust gas

• the internal-combustion engine control device including a processor and a memory, the memory storing instructions which when executed by the processor, cause the processor to perform the steps of:
• determining whether regeneration of the filter is required based on deposition amount of trapped in the filter;
• when regeneration of the filter is required, performing fuel cut control to temporarily stop supply of fuel to the internal-combustion engine to burn the particulate matter trapped in the filter and repeating the fuel cut control while performing exhaust temperature control for increasing a temperature of the exhaust gas of the internal-combustion engine;
• decreasing a period of time for which a supply of fuel to the internal-combustion engine is stopped in the fuel cut control as a deposition amount of particulate matter in the filter increases when a temperature of the filter before the fuel cut control is constant and decreasing the period of time as the temperature of the filter before the fuel cut control increases when the deposition amount of the particulate matter in the filter is constant;
• and
• estimating the deposition amount based on information on a differential pressure before and after the filter such that the deposition amount estimated after first fuel cut control is greater than the deposition amount estimated before the first fuel cut control when the differential pressure is constant.

A filter regeneration method for regenerating a filter that is provided in an exhaust path of an internal-combustion engine fueled by gasoline and traps particulate matter in exhaust gas of the internal-combustion engine, the filter regeneration method comprising:

• determining whether regeneration of the filter is required based on deposition amount of particulate matter trapped in the filter;
• when regeneration of the filter is required, performing fuel cut control to temporarily stop supply of fuel to the internal-combustion engine to burn the particulate matter trapped in the filter and repeating the fuel cut control while performing exhaust temperature control for increasing a temperature of the exhaust gas of the internal-combustion engine;
• in the exhaust temperature control, controlling the temperature of the exhaust gas before the fuel cut control to match a target temperature set for each instance of the fuel cut control and gradually increasing the target temperature each time the fuel cut control is performed;
• and
• estimating the deposition amount based on information on a differential pressure before and after the filter such that the deposition amount estimated after first fuel cut control is greater than the deposition amount estimated before the first fuel cut control when the differential pressure is constant.