MULTI-STAGE TURBOCHARGING SYSTEM WITH THERMAL BYPASS

摘要

A two-stage turbocharging system with a high pressure (HP) turbine and a low pressure (LP) turbine, the HP turbine having an inlet and an outlet and the LP turbine having an inlet and an outlet, as well as E-HP exhaust piping adapted for fluidly connecting an engine to said HP turbine inlet, HP-LP exhaust piping fluidly connecting said HP turbine outlet to said LP turbine inlet, LP-A exhaust piping fluidly connecting said LP turbine outlet to an aftertreatment device, and branched bypass piping having an inlet and first and second branches, each branch having an outlet, with the inlet being fluidly connected to the E-HP exhaust piping, with the first branch outlet being fluidity connected to the LP turbine inlet, with the second branch outlet being fluidly connected to the aftertreatment device, and with an R2S valve in said first branch and a warm-up valve in said second branch. By opening of the valve, exhaust gas can bypass both the HP and LP turbines and flow to the catalytic converter. In a preferred embodiment of the invention, the R2S valve and the warm-up valve are integrated into a single exhaust flow control unit.