Turbocharger with wastegate

Abstract

This invention relates to an actuator assembly for a turbocharger pressure control valve assembly and a method of assembling a pressure control assembly of a turbocharger. The assembly comprises an actuator coupled to an actuator rod which in use is coupled to the valve assembly to control the position thereof. The actuator rod comprises an elongate member at least a portion of which is flexible. The actuator rod may be a resilient member which may be substantially straight when unstressed. In use the actuator rod may extend in a substantially straight line between the actuator and the valve assembly.

Having thus described the invention, what is novel and desired to be secrued by Letters Patent of the United States is:  
     
         1 . An actuator assembly for a turbocharger pressure control valve assembly, the actuator assembly comprising an actuator coupled to an actuator rod which in use is coupled to the valve assembly to control the position thereof, wherein the actuator rod comprises an elongate member at least a portion of which is flexible.  
     
     
         2 . An actuator assembly according to  claim 1 , wherein the actuator rod is a resilient member.  
     
     
         3 . An actuator assembly according to  claim 2 , wherein the actuator rod is substantially straight when unstressed.  
     
     
         4 . An actuator assembly according to  claim 1 , wherein in use the actuator rod extends in a substantially straight line between the actuator and the valve assembly.  
     
     
         5 . An actuator assembly according to  claim 1 , wherein the actuator rod comprises a sleeveless cable.  
     
     
         6 . An actuator assembly according to  claim 5 , wherein the actuator rod comprises a multi-strand cable.  
     
     
         7 . An actuator assembly according to  claim 1 , wherein the actuator is a pneumatic actuator.  
     
     
         8 . An actuator assembly according to  claim 7 , wherein the pneumatic actuator comprises a spring loaded diaphragm or sliding seal housed within a pressure chamber, said diaphragm or seal being attached to a first end of the actuator rod.  
     
     
         9 . An actuator assembly according to  claim 8 , wherein said pressure chamber is provided with a guide formation adapted to direct force exerted by the actuator rod on the diaphragm/sliding seal along the direction of movement thereof.  
     
     
         10 . An actuator assembly according to  claim 9 , wherein said guide comprises a boss surrounding an opening through which the actuator rod extends into the pressure chamber.  
     
     
         11 . An actuator assembly according to  claim 10 , wherein the actuator comprises a sliding seal mounted within said pressure chamber, and said sliding seal is provided with guide means to resist any forces tending to pull the sliding seal of its intended direction of movement.  
     
     
         12 . A turbocharger comprising a compressor driven by an exhaust gas turbine wheel, said turbine wheel being rotatable within a housing having an inlet for exhaust gas and an outlet downstream of said turbine wheel, said turbine housing having a passageway that extends from said inlet to said outlet, thus bypassing said turbine wheel, said turbocharger further comprising a valve assembly displaceable between a position blocking flow through said bypass passageway and another position permitting flow, an actuator, and an actuator rod connected between said actuator and said valve assembly to displace said valve assembly, said actuator rod being elongate and at least a portion of said actuator rod being flexible.  
     
     
         13 . A turbocharger according to  claim 13 , wherein the end of the actuating rod remote from said actuator is secured to a lever arm extending from the valve assembly by way of which the valve is operated.  
     
     
         14 . A turbocharger according to  claim 13 , wherein said end of the actuator rod is secured to said lever arm such that there is no relative movement between the rod and lever arm at the point of connection.  
     
     
         15 . A turbocharger according to  claim 14 , wherein the actuator rod is clamped, crimped welded or bonded to said lever arm which is adapted accordingly.  
     
     
         16 . A turbocharger, according to  claim 15 , wherein the actuator rod comprises an elongate flexible member.  
     
     
         17 . A turbocharger, according to  claim 16 , wherein the actuator rod comprises a multi-strand cable.  
     
     
         18 . A method of assembling a pressure control assembly of a turbocharger, the turbocharger comprising a turbine housing and a compressor, the pressure control assembly comprising a valve assembly mounted within the turbine housing, a pneumatic actuator mounted to the turbocharger to receive pressurised air from the compressor or an external air supply, a flexible actuator rod extending from the pneumatic actuator, and a lever arm extending from the valve assembly and the turbine housing and linking the actuator rod to the valve assembly, the method comprising: 
 assembling the valve assembly and lever arm on the turbine housing;    assembling the pneumatic actuator and actuator rod as a sub-assembly;    mounting the pneumatic actuator/actuating rod sub-assembly to the turbocharger; and    securing the end of the actuator rod remote from the pneumatic actuator to the lever arm.    
     
     
         19 . A method according to  claim 18 , wherein the actuator rod is secured to the lever arm by one of clamping, crimping, welding or bonding.  
     
     
         20 . A method according to  claim 19 , wherein prior to securing the actuator rod to the lever arm, the valve assembly is held in a closed position by appropriate clamping of the lever arm and said pneumatic actuator is pressurised to a predetermined pressure, thereby to determine the minimum pressure at which said valve will in use begin to open.