Supercharged internal combustion engine

A supercharged internal combustion engine comprising:

• a throttle valve for controlling an amount of intake air introduced into a combustion chamber of the engine;
• a supercharger for supercharging intake air;
• a recirculation passage for recirculating a portion of exhaust gases discharged from the engine into an intake system;
• a control valve for controlling an amount of the exhaust gases to be recirculated form the recirculation passage;
• a first control means for controlling an air-fuel ratio of a mixed fuel to make the air-fuel ratio a lean air-fuel ratio which is leaner than a stoichiometric air-fuel ratio when the supercharger exists in a supercharging region which causes pressure of the intake air to increase its temperature higher than ambient temperature;
• and
• a second control means for controlling the control valve so as to recirculate the exhaust gases into the intake system during a time of the lean air-fuel ratio in the supercharging region.

A supercharged internal combustion engine comprising:

• a throttle valve for controlling an amount of intake air introduced into a combustion chamber of the engine;
• a supercharger for supercharging intake air;
• a recirculation passage for recirculating a portion of exhaust gases discharged from the engine into an intake system;
• a control valve for controlling an amount of the exhaust gases to be recirculated from the recirculation passage;
• a first control means for controlling an air-fuel ratio of a mixed fuel to make the air-fuel ratio a lean air-fuel ratio which is leaner than a stoichiometric air-fuel ratio when the supercharger exists in a supercharging region where an intake pressure detecting degree of pressure;
• and
• a second control means for controlling the control valve so as to recirculate the exhaust gases into an intake system at the time of the lean air-fuel ratio in the supercharging region.

A supercharged internal combustion engine comprising:

• a supercharger for supercharging intake air;
• a recirculation passage for recirculating a portion of exhaust gases discharged from the engine into an intake system upstream of the supercharger;
• a control valve for controlling an amount of the exhaust gases to be recirculated from the recirculation passage;
• a first control means for controlling an air-fuel ratio of a mixed fuel to make the air-fuel ratio a lean air-fuel ratio which is leaner than a stoichiometric air-fuel ratio when the supercharger exists in a supercharging region which includes a maximum load condition;
• and
• a second control means for controlling the control valve so as to recirculate the exhaust gases into an intake system at the time of the lean air-fuel ratio in the supercharging region.

A supercharged internal combustion engine comprising:

• a supercharger for supercharging intake air;
• a recirculation passage for recirculating a portion of exhaust gases discharged from the engine into an intake system upstream of the supercharger;
• a control valve for controlling an amount of the exhaust gases to be recirculated from the recirculation passage;
• a first control means for controlling an air-fuel ratio of a mixed fuel to make the air-fuel ratio a lean air-fuel ratio which is leaner than a stoichiometric air-fuel ratio when the supercharger exists in a supercharging region where the supercharger can demonstrate a substantial supercharging effect that causes pressure of the intake air to increase its temperature higher than ambient temperature;
• and
• a second control means for controlling the control valve so as to recirculate the exhaust gases into an intake system at the time of the lean air-fuel ratio in the supercharging region.