Patent ID: 8037684

Claim:
A variable-flow turbocharger comprising: a turbine housing defining a turbine chamber having an internal diameter; a turbine wheel mounted within the turbine chamber for rotation about an axis; an inlet passageway for introducing exhaust gas into the turbine chamber; an outlet passageway for discharging the exhaust gas from the turbine chamber; wherein the turbine chamber is defined collectively by an outer wall and an inner wall, wherein the outer wall and the inner wall are overlapping with the outer wall located radially outward of the inner wall, and an open space is defined between a radially outer surface of the inner wall and a radially inner surface of the outer wall, the open space being in fluid communication with the outlet passageway; at least the inner wall being axially movable relative to the turbine wheel from a closed position to an open position; wherein in the closed position of the inner wall, the internal diameter of the turbine chamber at an outlet side of the turbine wheel is defined by the inner wall such that the turbine chamber has a relatively small internal diameter at the outlet side of the turbine wheel, and wherein the inner wall in the closed position engages a portion of the outer wall so as to close off the open space and prevent exhaust gas from flowing through the open space; and wherein in the open position of the inner wall, an axial spacing of the inner wall from the turbine wheel is increased such that the internal diameter of the turbine chamber at the outlet side of the turbine wheel is defined by the outer wall and is thereby increased, and wherein the inner wall in the open position uncovers the open space such that exhaust gas that has passed through the turbine wheel flows through the open space to the outlet passageway.