Patent ID: 8070425
Filing Date: 2011-12-06
Classification: F01D,F02C,F05D

Abstract:
1. A turbocharger comprising: a compressor wheel affixed to one end of a shaft; a center housing containing a bearing assembly for the shaft; a turbine wheel affixed to an opposite end of the shaft and disposed in a bore of a turbine housing coupled to one side of the center housing, the turbine housing defining a chamber surrounding the turbine wheel, and a turbine nozzle being defined between fixed axially spaced first and second walls such that exhaust gas flows from the chamber through the turbine nozzle into the turbine wheel; a sliding piston disposed in the bore of the turbine housing such that the piston is axially slidable between a closed position and an open position, the piston having an end that is spaced from the first wall by a relatively small distance in the closed position of the piston and by a relatively large distance in the open position of the piston, an open axial extent of the nozzle being defined between the first wall and the end of the piston; a set of circumferentially spaced first vanes mounted on the first wall and each projecting in one axial direction toward the second wall and terminating at a tip; a set of circumferentially spaced second vanes mounted on the end of the piston and each projecting in an opposite axial direction toward the first wall and terminating at a tip; the first vanes being circumferentially staggered relative to the second vanes and overlapping the second vanes at least when the piston is closed and partially open; a pair of first leakage dams for every first vane, formed as projections from the end of the piston in a direction generally toward the first wall and having axial lengths substantially smaller than the first vanes, each said pair being positioned such that the tip of the respective first vane is between the two first leakage dams when the piston is fully closed; and a pair of second leakage dams for every second vane, formed as projections from the first wall in a direction generally toward the second wall and having axial lengths substantially smaller than the second vanes, each said pair being positioned such that the tip of the respective second vane is between the two second leakage dams when the piston is fully closed.