Patent ID: 6438956
Filing Date: 2002-08-27
Classification: F01N,F02B,F02D,Y02T

Abstract:
Method of operating an internal-combustion engine of the Otto type, comprising:discharging exhaust gases from a plurality of cylinders of the engine for driving a turbocompressor which has an exhaust-gas driven turbine for supercharging the engine, wherein at low load, running the engine with a stoichometric air-fuel mixture ratio, and at high load, running the engine with a lean air-fuel mixture ratio during supercharging, the fuel quantity being kept at a level corresponding to stoichiometric conditions at normal charging pressure, the method further comprising: increasing the charging pressure above the normal charging pressure in a single stage until the stoichometric air-fuel mixture ratio increases to the lean air-fuel mixture ratio of at least 19:1 while maintaining the fuel quantity level during a shift to the lean air-fuel mixture; and dividing an exhaust-gas discharge pulse from the cylinders such that a first part of the exhaust-gas discharge pulse is conducted to the turbine of the turbocompressor while a subsequent part of the same exhaust-gas discharge pulse is conducted past the turbine of the turbocompressor.