Patent ID: 7930888

Claim:
A method of operating a turbocharger in an internal combustion engine having a variable geometry turbine and a compressor driven by said turbine, a substantially annular turbine inlet passageway defined between a substantially radial face of a first wall and a facing second wall of the housing, a substantially annular array of turbine vanes extending across said inlet passageway and defining vane surfaces, turbine vane passages being defined between the vanes for directing exhaust gas flow between adjacent vane surfaces towards the turbine wheel, each of said vanes being fixed to said first wall, a respective opening for receiving the each of said vanes being provided in the second wall, and at least one of the turbine vanes having at least one recess formed in a vane surface, the method comprising: stopping a fuel supply to an internal combustion engine when in an engine braking mode; moving a first and second wall of the variable geometry turbine relative to one another to reduce a size of the turbine inlet passageway; and substantially aligning the at least one recess formed in the vane surface of the variable geometry turbine with the opening in the second wall for receiving a vane of the first wall so as to provide exhaust gas leakage flow path.