Patent ID: 8291703
Filing Date: 2012-10-23
Classification: F01D,F02B,Y02T

Abstract:
1. A variable geometry turbine comprising a turbine wheel mounted within a housing for rotation about a turbine axis, a gas inlet chamber, a gas flow inlet passage downstream of the inlet chamber and upstream of said turbine wheel, the inlet passage being defined between a moveable first wall and a second wall, an actuator operable to control displacement of the first wall in order to vary the size of the gas flow inlet passage, a piston member associated with the first wall and received in a piston chamber defined by a piston chamber wall, the first wall being moveable as a result of displacement of the piston member in the piston chamber, a bypass passage defined in the housing and extending from a location in the turbine upstream of the inlet passage to the piston chamber where it penetrates the piston chamber wall, so that gas in the bypass passage is directed through the piston chamber wall into the piston chamber thus bypassing the inlet passage, the bypass passage being disposed such that gas introduced through the bypass passage pressurises the chamber so as to apply a force that urges the piston member in a direction that causes the first wall to move towards the second wall.