Patent ID: 8695337

Claim:
A variable geometry turbocharger, comprising a turbine housing, a bearing housing and a compressor housing; a shaft supported in the bearing housing and coupling a turbine within the turbine housing and a compressor within the compressor housing; a turbine inlet volute, and at least one side wall of an annular turbine inlet passage, defined by the turbine housing; a circular interface surface, defined by respective mating surfaces of the turbine housing and the bearing housing, and having a radially peripheral annular portion arranged at a first axial location; a variable geometry turbine mechanism including an axially slidable cylinder arranged to vary the cross sectional area of the annular turbine inlet passage; a piston ring disposed against an outer surface of the axially slidable cylinder and located within an annular groove at a radially inboard end of the circular interface surface, the piston ring arranged at a second axial location different from the first axial location; and an annular spacing element located between the piston ring and the bearing housing and disposed axially adjacent to the piston ring, the annular spacing element and the turbine housing defining the annular groove.