Patent ID: 7628580

Claim:
A variable geometry turbine comprising: a turbine housing defining a turbine chamber within which a turbine wheel is mounted for rotation about a turbine axis; the turbine chamber having a radially extending annular inlet defined between facing annular side walls of the turbine housing, the annular inlet having an axial width defined between said annular side walls; an annular array of swing vanes mounted within the inlet, each vane having an axial length extending across the inlet between chordal vane edges lying adjacent respective annular side walls of the annular inlet, and a chordal length defined between leading and trailing vane edges extending across the inlet upstream and downstream respectively having regard to direction of flow through the turbine; means for pivoting each vane about a respective pivot axis extending across the inlet to adjust the effective cross-section area of the annular inlet, each vane being pivotable between a first position in which the area of the inlet is a minimum and a second position in which the area of the inlet is a maximum; wherein at least one of said annular side walls is configured so that clearance between said side wall and at least a portion of the adjacent chordal edge of each vane varies in a predetermined manner as the vane moves between positions intermediate said first and second vane positions; wherein at least one of the annular side walls is configured so that the axial width of the annular inlet increases from a minimum width to a maximum width with decreasing radius; and wherein the variation in axial width of the annular inlet begins at a radius smaller than the radial position of the trailing edge of each vane when in said first position.