Device for controlling the pitch of fan blades of a turboprop

Abstract

The invention relates to a device for controlling the pitch of fan blades of a turboprop. The device includes at least at least one set of adjustable pitch fan blades secured to rotate with a rotary ring centered on a longitudinal axis and mechanically connected to a turbine rotor. Each blade of the set is coupled for pitch-adjustment purposes with a synchronization ring centered on the longitudinal axis, the synchronization ring being suitable for pivoting about the longitudinal axis relative to the rotary ring under drive from actuators carried by the rotary ring and each having a respective axis extending in a direction that is substantially tangential to the synchronization ring.

1 . A device for controlling the pitch of fan blades of a turboprop having at least one set of adjustable pitch fan blades, said set being constrained to rotate with a rotary ring centered on a longitudinal axis and being mechanically connected to a turbine rotor, wherein each blade of the set is coupled, for pitch-adjustment purposes, to a synchronization ring centered on the longitudinal axis, said synchronization ring being suitable for pivoting about the longitudinal axis relative to the rotary ring under drive from actuators, each comprising a cylindrical tube fastened to the rotary ring and having a rigid rod suitable for sliding therein, the rod extending in a direction that is substantially tangential to the synchronization ring and having its free end fastened to the synchronization ring. 
   
   
       2 . A device according to  claim 1 , further including means for providing longitudinal and radial guidance to the synchronization ring relative to the rotary ring. 
   
   
       3 . A device according  claim 2 , having a plurality of wheel means carried by the rotary ring and co-operating with running tracks formed on the synchronization ring so as to provide it with longitudinal and radial guidance relative to the rotary ring. 
   
   
       4 . A device according  claim 3 , wherein the outside surface of the synchronization ring has two parallel running tracks extending in a circumferential direction and separated by a projecting rib, the wheel means each comprising two wheels rotatable about respective axes parallel to the longitudinal axis and each co-operating with a running track. 
   
   
       5 . A device according  claim 1 , wherein each blade is mounted on the rotary ring by means of a support suitable for pivoting about a radial axis and connected to the synchronization ring via a drive controlling rod. 
   
   
       6 . A device according  claim 1 , wherein each actuator is fastened to the rotary ring by means of lugs having respective axes that coincide and that are parallel to the longitudinal axis. 
   
   
       7 . A device according  claim 1 , wherein the rotary ring presents a polygonal shape and is provided with openings in which the actuators are mounted. 
   
   
       8 . A device according  claim 1 , wherein the set has ten fan blades, the synchronization ring being suitable for pivoting under drive from five actuators. 
   
   
       9 . A two-propeller turboprop comprising a turbine having two contrarotating rotors and two sets of adjustable-pitch fan blades constrained to rotate with two rotary rings connected to respective ones of the rotors, the pitch of the fan blades of at least one of the sets being controlled by a device according to  claim 1 .