Inlet-adjustment mechanism for turbocharger compressor, having sealing means preventing recirculation and/or oil migration into the mechanism

A turbocharger, comprising:

• a turbine housing and a turbine wheel mounted in the turbine housing and connected to a rotatable shaft for rotation therewith, the turbine housing receiving exhaust gas and supplying the exhaust gas to the turbine wheel;
• a centrifugal compressor assembly comprising a compressor housing and a compressor wheel mounted in the compressor housing and connected to the rotatable shaft for rotation therewith, the compressor housing having an air inlet wall defining an air inlet for leading air generally axially into the compressor wheel, the air inlet wall defining an annular space surrounding the air inlet and open to the air inlet at a radially inner end of the annular space;
• and
• a compressor inlet-adjustment mechanism disposed in the annular space of the air inlet wall and movable between an open position and a closed position, the inlet-adjustment mechanism comprising a plurality of blades disposed between an upstream wall surface and a downstream wall surface within the annular space, the blades collectively circumscribing an orifice, an upstream surface of each blade opposing the upstream wall surface and a downstream surface of each blade opposing the downstream wall surface, the blades being movable inwardly from the annular space into the air inlet when the blades are in the closed position so as to cause the orifice to have a reduced diameter relative to a nominal diameter of the inlet;
• and
• at least one of an upstream blade seal formed between the upstream wall surface and an upstream sealing surface defined by each blade when the blades are moved inwardly to the closed position, and a downstream blade seal formed between the downstream wall surface and a downstream sealing surface defined by each blade when the blades are moved inwardly to the closed position.