Exhaust gas recirculation distribution variation sensing device

An exhaust gas recirculation distribution variation sensing device for a multi-cylinder internal combustion engine having a plurality of cylinders and a plurality of injectors respectively provided to the cylinders, the internal combustion engine being structured to distribute recirculated exhaust gas, which is recirculated from an exhaust system to an intake system, to the respective cylinders, the exhaust gas recirculation distribution variation sensing device comprising:

• a torque sensing means for sensing instantaneous torque caused with combustion of fuel injected from the injector or a physical quantity relevant to the instantaneous torque for each cylinder;
• an injection quantity sensing means for sensing an actual injection quantity of the injected fuel or a physical quantity relevant to the injection quantity for each cylinder;
• and
• an exhaust gas recirculation distribution variation calculating means for calculating an exhaust gas recirculation distribution variation as distribution variation of the recirculated gas to the respective cylinders based on a variation in the torque sensing value of the torque sensing means among the cylinders and a variation in the injection quantity sensing value of the injection quantity sensing means among the cylinders,
• wherein the internal combustion engine has an exhaust gas recirculation valve for regulating a quantity of the recirculated exhaust gas, the exhaust gas recirculation distribution variation sensing device further comprising:
• a small injection controlling means for performing small injections sequentially in the respective cylinders for injecting a small quantity of fuel from each injector regardless of manipulation, which is performed by a driver to operate the internal combustion engine, in a state where the exhaust gas recirculation valve is fully closed;
• a cylinder characteristic variation calculating means for calculating a cylinder characteristic variation as a variation in a cylinder characteristic among the cylinders based on a variation in an actual injection quantity of the small injection or a physical quantity relevant to the injection quantity among the cylinders and a variation in an increase amount of output torque caused in connection with the small injection or a physical quantity relevant to the increase amount among the cylinders;
• and
• an exhaust gas recirculation distribution variation correcting means for correcting the exhaust gas recirculation distribution variation by subtracting the cylinder characteristic variation from the exhaust gas recirculation distribution variation.

A method of sensing exhaust gas recirculation distribution variation for a multi-cylinder internal combustion engine having a plurality of cylinders and a plurality of injectors respectively provided to the cylinders, the internal combustion engine being structured to distribute recirculated exhaust gas, which is recirculated from an exhaust system to an intake system, to the respective cylinders, the method comprising:

• sensing instantaneous torque caused with combustion of fuel injected from the injector or a physical quantity relevant to the instantaneous torque for each cylinder;
• sensing an actual injection quantity of the injected fuel or a physical quantity relevant to the injection quantity for each cylinder;
• and
• calculating an exhaust gas recirculation distribution variation based on a variation in the torque sensing value among the cylinders and a variation in the injection quantity sensing value among the cylinders, wherein the exhaust gas recirculation distribution is a variation among inflow quantities of the recirculated exhaust gas flowing into the respective cylinders at the time when the recirculated exhaust gas is lead from an intake passage of the engine and flows into the respective cylinders.