Method for warm-up of catalyst of exhaust gas treatment device

An engine system comprising:

• an engine block having a plurality of combustion chambers;
• an intake manifold for supplying intake to the combustion chambers;
• an exhaust manifold for discharging exhaust from the combustion chambers;
• an exhaust gas treatment device including catalyst located in the engine exhaust path communicating with the exhaust manifold;
• an exhaust gas recirculation (EGR) system driven in response to an EGR command signal to recirculate exhaust to the engine intake path communicating with the intake manifold;
• an engine controller;
• and
• a computer readable storage medium having instructions stored thereon that are executable by the engine controller to perform a method of controlling the internal combustion engine for warm-up the catalyst, wherein the medium includes instructions for operating the engine controller to:
• generate a warm-up demand for heating the catalyst subject to constraint on stable combustion;
• determine a reduction in excess air ratio of the engine intake based on the warm-up demand;
• modify a desired value in excess air ratio by the reduction to provide a modified desired value in excess air ratio;
• modify a desired value in EGR rate based on the reduction to provide a modified desired value in EGR rate;
• and
• determine the EGR command signal based on the modified desired value in EGR rate.

An apparatus of controlling an internal combustion engine for warm-up of catalyst of an exhaust gas treatment device located in the engine exhaust path, the engine including an exhaust gas recirculation (EGR) system driven in response to an EGR command signal to recirculate exhaust to an engine intake, the apparatus comprising:

• a logic block that generates a warm-up demand for heating the catalyst subject to constraint on stable combustion;
• a reduction block that determines a reduction in excess air ratio of the engine intake based on the warm-up demand;
• an excess air ratio modifier block that modifies a desired value in excess air ratio by the reduction to provide a modified desired value in excess air ratio;
• an EGR rate modifier block that modifies a desired value in EGR rate based on the reduction to provide a modified desired value in EGR rate;
• and
• an EGR controller that determines the EGR command signal based on the modified desired value in EGR rate.

A computer readable storage medium having instructions stored thereon that are executable by a controller to perform a method of controlling an internal combustion engine for warm-up of catalyst of an exhaust gas treatment device located in the engine exhaust path, the engine including an exhaust gas recirculation (EGR) system driven in response to an EGR command signal to recirculate exhaust to an engine intake, the computer readable storage medium comprising:

• instructions for generating a warm-up demand for heating the catalyst subject to constraint on stable combustion;
• instructions for determining a reduction in excess air ratio of the engine intake based on the warm-up demand;
• instructions for modifying a desired value in excess air ratio by the reduction to provide a modified desired value in excess air ratio;
• instructions for modifying a desired value in EGR rate based on the reduction to provide a modified desired value in EGR rate;
• and
• instructions for determining the EGR command signal based on the modified desired value in EGR rate.

A computer readable storage medium having instructions stored thereon that are executable by a controller to perform a method of controlling an internal combustion engine for warm-up of catalyst of an exhaust gas treatment device located in the engine exhaust path, the engine including an exhaust gas recirculation (EGR) system driven in response to an EGR command signal to recirculate exhaust to an engine intake, the computer readable storage medium comprising:

• instructions for determining whether a need remains for warm-up of the catalyst;
• instructions for determining whether in-cylinder combustion environment allows for engine operation with reduced excess air ratio to increase the temperature of the catalyst;
• and
• instructions for generating a warm-up demand when the in-cylinder combustion environment allows for the engine operation under the presence of the need.

A computer readable storage medium having instructions stored thereon that are executable by a controller to perform a method of controlling an internal combustion engine for warm-up of catalyst of an exhaust gas treatment device located in the engine exhaust path, the engine including an exhaust gas recirculation (EGR) system driven in response to an EGR command signal to recirculate exhaust to an engine intake, the computer readable storage medium comprising:

• instructions for determining whether a need remains for warm-up of the catalyst;
• instructions for determining whether the engine has achieved self-sustained operation;
• instructions for increasing warm-up demand at a controlled rate after the engine has achieved self-sustained operation;
• and
• instructions for generating a warm-up demand under the presence of the need.