US Patent 10502126 Adjustable-trim centrifugal compressor for a turbocharger

A centrifugal compressor for a turbocharger includes an inlet-adjustment mechanism in an air inlet for the compressor, operable to move between an open position and a closed position in the air inlet. The inlet-adjustment mechanism includes a plurality of vanes formed as ring segments and disposed about the air inlet and each movable circumferentially and radially inwardly through a slot in the air inlet wall so as to form an orifice of reduced diameter relative to a nominal diameter of the inlet. Movement of the inlet-adjustment mechanism from the open position to the closed position is effective to shift the compressor's surge line to lower flow rates.