Control methods and control apparatuses of internal-combustion engines

摘要

An internal-combustion engine (10) has a turbo supercharger (30). A control apparatus (50) calculates a fuel flow rate based on an injection quantity of fuel in the engine (10) and a number of revolutions of the engine (10). The control apparatus (50) calculates an upstream side pressure and temperature on an upstream side of a turbine impeller (36A) and a turbine flow rate. The control apparatus (50) calculates an upper limit threshold value of an opening degree level of a variable nozzle (33) of the turbo supercharger (30) such that a turbine pressure ratio is equal to or less than a predetermined ratio on a basis of the turbine flow rate and a pressure ratio-turbine flow rate characteristic. The pressure ratio-turbine flow rate characteristic is pre-stored information indicating a relationship between the turbine pressure ratio, the turbine flow rate, and the opening degree level of the variable nozzle (33). The control apparatus (50) controls an opening degree of the variable nozzle (33) so as to be an opening degree equal to or less than the upper limit threshold value.