Turbocharger bypass system

Abstract

A turbocharger bypass system and method for minimizing the occurrence of oil seepage from the bearing housing into the compressor housing as a result of a pressure differential across the bearing housing and the compressor housing. A bypass system with a pressure dependent check valve is connected to the inlet air passage of a turbocharged engine. When the pressure in the inlet air passage drops to below atmosphere or a predetermined level of depression, the check valve opens to allow a flow of atmospheric air into the inlet air passage, thus minimizing or eliminating the pressure differential generated as a result of a vacuum in the inlet air passage during motoring conditions, or when an exhaust valve downstream of the turbocharger is closed, such as during engine braking. The bypass system is applicable to both single stage and dual stage turbocharged internal combustion engines.

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