Retractable vane diffuser for compressors

Abstract

A retractable vane diffuser system ( 36 ) for a compressor stage ( 12 ) of a turbocharger with selectively retractable vanes ( 38 ). The retractable vane diffuser system ( 36 ) includes a retractable vane ( 38 ) or a set of vanes ( 40 ) that can extend into a flow path ( 34 ) of a diffuser ( 18 ) to help control airflow and change the operating characteristics of the compressor stage ( 12 ), such as improving surge margin or improving peak stage efficiency. The vanes ( 38 ) can retract preferably with a vane ring ( 44 ) into a cavity ( 42 ) of a wall ( 30 or 32 ) of the diffuser ( 18 ) when operation as a vaneless diffuser is desired to maximize flow, such as to slow onset of diffuser stall or surge. The retractable vane diffuser system ( 36 ) combines superior pressure ratio, efficiency, and lower mass air flow operating characteristics of a diffuser having vanes with higher mass airflow capacity of a vaneless diffuser.

What is claimed: 
     
         1 . A turbocharger having a compressor impeller ( 14 ) and a turbine wheel connected by a rotating shaft, the improvement comprising a retractable vane diffuser system ( 36 ) including:
 a diffuser ( 18 ) defined by a hub wall ( 30 ) and a shroud wall ( 32 ) forming a flow path ( 34 ) for air as it leaves the compressor impeller ( 14 ); and   a vane ( 38 ) retractable into the hub wall ( 30 ) or the shroud wall ( 32 ).   
     
     
         2 . The turbocharger of  claim 1  wherein operational stability at low mass airflows is improved by controlling airflow. 
     
     
         3 . The turbocharger of  claim 1  wherein the vane ( 38 ) is one of a plurality of vanes. 
     
     
         4 . The turbocharger of  claim 1  further comprising a set of vanes ( 40 ) on a vane ring ( 44 ), the set of vanes ( 40 ) retractable into each of the hub wall ( 30 ) and the shroud wall ( 32 ). 
     
     
         5 . The turbocharger of  claim 1  wherein the vane ( 38 ) is separate from adjacent vanes. 
     
     
         6 . The turbocharger of  claim 5  wherein the vane ( 38 ) can be retracted while adjacent vanes are extended. 
     
     
         7 . The turbocharger of  claim 1  further comprising a vane ring ( 44 ) in a cavity ( 42 ) of the shroud wall ( 32 ) of the diffuser ( 18 ), the vane ring ( 44 ) including a plurality of vanes ( 38 ) retractable into the shroud wall ( 32 ). 
     
     
         8 . The turbocharger of  claim 1  wherein activation of the retractable vane diffuser system ( 36 ) is caused by mass airflow, wherein lower mass airflow causes the vane ( 38 ) to extend into the flow path ( 34 ), and wherein higher mass airflow causes the vane ( 38 ) to retract. 
     
     
         9 . The turbocharger of  claim 1  wherein activation of the retractable vane diffuser system ( 36 ) is caused by acceleration or deceleration of the turbocharger, wherein rapid acceleration or deceleration causes the vane ( 38 ) to extend into the flow path ( 34 ), and wherein the vane ( 38 ) is retracted at steady high speed. 
     
     
         10 . The turbocharger of  claim 1  wherein a single actuator controls the retractable vane diffuser system ( 36 ) and a set of Variable Turbine Geometry (VTG) vanes, wherein the single actuator causes the vane ( 38 ) to extend into the flow path ( 34 ) when the VTG vanes are in a closed position, and wherein the single actuator is operably connected to the turbine wheel. 
     
     
         11 . A turbocharger for an internal combustion engine comprising a compressor impeller ( 14 ) and a turbine wheel connected by a rotating shaft, the compressor impeller ( 14 ) operably connected and adjacent to a retractable vane diffuser system ( 36 ) with vanes ( 38 ) that fully retract into a wall ( 30  or  32 ) of a diffuser ( 18 ) and selectively extend from the wall ( 30  or  32 ) of the diffuser ( 18 ) into a flow path ( 34 ) of the diffuser ( 18 ). 
     
     
         12 . The turbocharger of  claim 11  wherein activation of the retractable vane diffuser system ( 36 ) is driven by mass airflow wherein lower mass airflow causes the vanes ( 38 ) to extend into the flow path ( 34 ) and higher mass airflow causes the vanes ( 38 ) to retract. 
     
     
         13 . The turbocharger of  claim 11  wherein activation of the retractable vane diffuser system ( 36 ) is caused by acceleration or deceleration of the turbocharger, wherein rapid acceleration or deceleration causes the vanes ( 38 ) to extend into the flow path ( 34 ), and wherein the vanes ( 38 ) are retracted when acceleration is slower. 
     
     
         14 . The turbocharger of  claim 11  including a movable vane ring ( 44 ) in a cavity ( 42 ) of the wall ( 30  or  32 ) of the diffuser ( 18 ). 
     
     
         15 . The turbocharger of  claim 11  including a movable vane ring ( 44 ) in each wall ( 30  and  32 ) of the diffuser ( 18 ) wherein alternating vanes ( 38 ) can be retracted or extended.