Patent ID: 9353677
Filing Date: 2016-05-31
CPC Classification: F02B,F02D,Y02T

Claim Text:
1. A control method of an internal-combustion engine having a turbo supercharger with a variable nozzle capable of adjusting a flow velocity of gas exhausted to a turbine impeller, and an opening degree adjustment device configured to adjust an opening degree of the variable nozzle, the method executed by a control apparatus comprising the steps of: determining a fuel flow rate according to an injection command signal sent to an injector for injecting fuel in the internal-combustion engine and a number of revolutions of the internal-combustion engine according to a detection signal from an internal-combustion engine revolution number detection device; determining an upstream side pressure on an upstream side of the turbine impeller; determining an upstream side temperature on the upstream side of the turbine impeller; determining a turbine flow rate of gas flowing toward the turbine impeller; determining an upper limit threshold value of an opening degree level of the variable nozzle such that a turbine pressure ratio is equal to or less than a predetermined ratio according to the turbine flow rate and a pressure ratio•turbine flow rate characteristic, wherein the turbine pressure ratio is a ratio of the upstream side pressure to a downstream side pressure of the turbine impeller, wherein 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; controlling an opening degree of the variable nozzle to be the opening degree level equal to or less than the upper limit threshold value, wherein the control apparatus determines the upstream side pressure according to an intake air flow rate received in the internal-combustion engine, the fuel flow rate, and an atmospheric pressure, wherein the control apparatus determines the upstream side temperature according to an injection quantity, the intake air flow rate, and the fuel flow rate and wherein the control apparatus determines the turbine flow rate according to the fuel flow rate, the intake air flow rate, the upstream side pressure, and the upstream side temperature.