Patent ID: 7497654

Claim:
A method for operating a variable nozzle device ( 1 ) for a turbocharger comprising a plurality of vanes ( 4 ) arranged in a nozzle ( 3 ) defined between an inner wall ( 11 ) and an outer wall ( 10 ), the vanes ( 4 ) forming nozzle passages, the method comprising the steps of: adjusting the nozzle passages by controllably adjusting the vanes ( 4 ), varying an axial clearance between the outer wall ( 10 ) and the vanes ( 4 ) by axially moving the outer wall ( 10 ) to and from the vanes ( 4 ), and increasing the axial clearance between the outer wall ( 10 ) and the vanes ( 4 ) as the operational rotational speed of the turbocharger increases, and decreasing the axial clearance between the outer wall ( 10 ) and the vanes ( 4 ) as an operational rotational speed of the turbocharger decreases, wherein the step of increasing the axial clearance between the outer wall ( 10 ) and the vanes ( 4 ) starts and/or stops either independently from or simultaneously with a step of pivoting the vanes ( 4 ) for enlarging the gas flow area of the annular nozzle ( 3 ), and/or the step of decreasing the axial clearance between the outer wall ( 10 ) and the vanes ( 4 ) starts and/or stops either independently from or simultaneously with a step of pivoting the vanes ( 4 ) for reducing the gas flow area of the annular nozzle ( 3 ).