Patent ID: 7010914

Claim:
A method for controlling boost pressure to prevent compressor surge in a turbocharged Diesel engine during temporary operation in one of a stoichiometric or richer combustion mode, comprising: defining the surge limits of a compressor of said turbocharger; reducing the flow of intake air during said temporary operation in one of a stoichiometric or richer combustion mode to provide exhaust gases that are substantially free of excess oxygen; determining the intake air pressure ratio between an inlet and an outlet of said compressor during said temporary operation in one of a stoichiometric or richer combustion mode; passing controlled amounts of intake air discharged from said compressor outlet to one of an ambient environment and an exhaust gas conduit positioned downstream of a regenerable exhaust gas aftertreatment device, said controlled amounts of intake air passed to one of an ambient environment and an exhaust gas conduit being sufficient to lower the pressure of the intake air discharged from said compressor outlet and prevent compressor surge during said temporary operation in a stoichiometric or richer combustion mode.