Turbocharger with magnetic brake

Abstract

Turbochargers are disclosed that have a braking system to brake the rotation of an electrically conductive compressor wheel within the turbocharger. The brake system includes the electrically conductive compressor wheel, which is connected to a turbine by a common shaft, one or more electromagnets positioned proximate to the compressor wheel, and a control circuit electrically coupled to the one or more electromagnets to turn the one or more electromagnets on or off to provide braking action to the compressor wheel. Systems including such a turbocharger and methods utilizing such turbochargers are also included herein.

What is claimed is: 
     
         1 . A turbocharger comprising:
 an electrically conductive compressor wheel connected to a turbine by a common shaft;   one or more electromagnets positioned proximate to the compressor wheel; and   a control circuit electrically coupled to the one or more electromagnets to turn the one or more electromagnets on or off to provide braking action to the compressor wheel.   
     
     
         2 . The turbocharger of  claim 1 , wherein the control circuit is electrically coupled to an engine control unit and receives a signal therefrom to control the braking of the compressor wheel in coordination with at least one engine function to avoid a surge of the compressor wheel or over revving of the turbine. 
     
     
         3 . The turbocharger of  claim 1 , wherein the one or more electromagnets are positioned between an ambient air inlet and a side of the compressor wheel facing the ambient air inlet. 
     
     
         4 . The turbocharger of  claim 3 , wherein the one or more electromagnets are positioned more proximal to an edge of the compressor wheel defining the compressor wheel's outer diameter than a bore defining the compressor wheel's inner diameter. 
     
     
         5 . The turbocharger of  claim 1 , wherein the one or more electromagnets is a plurality of electromagnets mounted equally distant from one another in a concentric arrangement about a central longitudinal axis of the turbocharger. 
     
     
         6 . The turbocharger of  claim 1 , wherein the one or more electromagnets are embedded in a surface of a housing enclosing the compressor wheel. 
     
     
         7 . The turbocharger of  claim 1 , further comprising a wastegate operatively connected in a fluid flowpath leading to an exhaust inlet in fluid communication with the turbine. 
     
     
         8 . A method for controlling the rotational speed of a turbocharger, the method comprising:
 providing a turbocharger having an electrically conductive compressor wheel connected to a turbine by a common shaft and a braking system comprising one or more electromagnets positioned proximate to the compressor wheel and a control circuit electrically coupled to the one or more electromagnets to turn the one or more electromagnets on or off to provide braking action to the compressor wheel;   operating the control circuit to allow electric current to flow to the one or more electromagnets to create a magnetic field to slow the rotations of the compressor wheel.   
     
     
         9 . The method of  claim 8 , further comprising:
 operating the control circuit to stop the flow of electric current to the one or more electromagnets.   
     
     
         10 . The method of  claim 8 , wherein the one or more electromagnets are positioned between an ambient air inlet and a side of the compressor wheel facing the ambient air inlet. 
     
     
         11 . The method of  claim 8 , wherein the one or more electromagnets are positioned more proximal to an edge of the compressor wheel defining the compressor wheel's outer diameter than a bore defining the compressor wheel's inner diameter. 
     
     
         12 . The method of  claim 8 , wherein the one or more electromagnets is a plurality of electromagnets mounted equally distant from one another in a concentric arrangement about a central longitudinal axis of the turbocharger. 
     
     
         13 . The method of  claim 8 , wherein the one or more electromagnets are embedded in a surface of a housing enclosing the compressor wheel. 
     
     
         14 . The method of  claim 8 , wherein the turbocharger is part of an engine system having an engine control unit electrically coupled to the control unit, and the method further comprises;
 sending signals from the engine control unit to the control circuit to activate or de-activate the one or more electromagnets in coordination with at least one engine function.   
     
     
         15 . The method of  claim 8 , further comprising a wastegate operatively connected in a fluid flowpath leading to an exhaust inlet in fluid communication with the turbine.