ADJUSTABLE-TRIM CENTRIFUGAL COMPRESSOR, AND TURBOCHARGER HAVING SAME

摘要

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 an axially elongated ring. In the open position, the radially outer surface of the ring is spaced from a tapering inner surface of the air inlet so that air can flow in an annular passage between the tapering surface and the ring. In the closed position, the ring abuts the tapering surface to close off the annular passage, whereby the effective inlet diameter is then defined by the inner diameter of the ring at its trailing edge. 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.

主权项

1. 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 wheel having blades and defining an inducer portion, the compressor housing defining an air inlet for leading air generally axially into the compressor wheel, the compressor housing further defining a volute for receiving compressed air discharged generally radially outwardly from the compressor wheel, the air inlet having a an inner surface a portion of which comprises a sliding surface that extends for an axial length along a downstream direction, followed by a shroud surface that is adjacent to outer tips of the blades of the compressor wheel; a compressor inlet-adjustment mechanism disposed in the air inlet of the compressor housing and movable between an open position and a closed position, the inlet-adjustment mechanism comprising an axially elongated ring whose inner surface becomes smaller in diameter in the downstream direction toward the compressor wheel, the ring terminating at a trailing edge, the inner diameter of the ring at the trailing edge being smaller than an inner diameter of the shroud surface of the compressor housing at the inducer portion of the compressor wheel, wherein the ring is arranged so that when the inlet-adjustment mechanism is in the open position the trailing edge of the ring is axially spaced relatively farther upstream from the inducer portion such that an effective diameter of the air inlet at the inducer portion is determined by the shroud surface, and wherein the trailing edge of the ring in the closed position is axially spaced relatively closer to the inducer portion of the compressor wheel such that the effective diameter of the air inlet at the inducer portion is determined by the inner diameter of the ring at the trailing edge.