Exhaust gas purification apparatus for internal combustion engine and method thereof

An exhaust gas purification apparatus for an intemal combustion engine, comprising:

• a filter disposed in an exhaust passage arranged in fluid communication with the internal combustion engine, that traps particulate matter in exhaust gas in the exhaust passage;
• a three-way catalyst, carried on the filter;
• and
• control means for simultaneously performing regeneration of the filter to remove accumulated particulate matter and for purifying the three-way catalyst, by controlling at least one engine operating parameter related to combustion of the internal combustion engine, such that exhaust gas flowing out of the internal combustion engine has a lean air-fuel ratio and the exhaust gas flowing into the filter has a lean air-fuel ratio and the exhaust gas flowing out of the filter has a substantially stoichiometric air-fuel ratio;
• wherein the exhaust passage is shaped such that all of the exhaust gas always passes through the filter and the three-way catalyst before exiting from the exhaust passage.

An exhaust gas purification method for an exhaust gas purification apparatus for an internal combustion engine, wherein the exhaust gas purification apparatus comprises:

• a filter disposed in an exhaust passage arranged in fluid communication with the internal combustion engine, that traps particulate matter in exhaust gas in the exhaust passage,
• a three-way catalyst carried on the filter, and
• a control unit,
• wherein the exhaust passage is shaped such that all of the exhaust gas always passes through the filter and the three-way catalyst before exiting from the exhaust passage, the method comprising:
• simultaneously performing regeneration of the filter to remove accumulated particulate matter and purification of the three-way catalyst, by controlling at least one engine operating parameter related to combustion of the internal combustion engine, such that exhaust gas flowing out of the intemal combustion engine has a lean air-fuel ratio and the exhaust gas flowing into the filter has a lean air-fuel ratio and the exhaust gas flowing out of the filter has a substantially stoichiometric air-fuel ratio.

A control unit for an exhaust gas purification system, comprising:

• a sensor input;
• and
• a signal output;
• wherein the control unit is configured to simultaneously perform regeneration of a filter to remove accumulated particulate matter and to purify of a three-way catalyst, by controlling at least one engine operating parameter related to combustion of an internal combustion engine, such that exhaust gas flowing out of the internal combustion engine has a lean air-fuel ratio and the exhaust gas flowing into the filter has a lean air-fuel ratio and the exhaust gas flowing out of the filter has a substantially stoichiometric air-fuel ratio;
• wherein the exhaust gas purification system comprises an exhaust passage shaped such that all of the exhaust gas always passes through the filter and the three-way catalyst before exiting from the exhaust passage.