US 7,530,784 B2
Device for controlling variable-pitch vanes in a turbomachine
Francois Pierre Georges Maurice Ribassin, Villabe (France); and Dominique Raulin, Avon (France)
Assigned to SNECMA, Paris (France)
Filed on Feb. 01, 2006, as Appl. No. 11/344,207.
Claims priority of application No. 05 01922 (FR), filed on Feb. 25, 2005.
Prior Publication US 2006/0285969 A1, Dec. 21, 2006
Int. Cl. F03B 3/18 (2006.01)
U.S. Cl. 415—160 12 Claims
OG exemplary drawing
 
1. A device for controlling variable-pitch vanes in a turbomachine, the device comprising a control ring mounted to turn about the casing of the turbomachine and connected by rods to the variable-pitch vanes, each rod having at one end a radial finger for assembly in the control ring, and at its other end an orifice for assembly on a drive square formed at the end of a cylindrical pin of the vane, which pin is pivotally guided in a cylindrical passage of the casing, wherein, for the cylindrical pin of the vane having an axis that is inclined relative to the axis of the radial finger of the rod, the assembly orifice in the rod presents a dimension in the longitudinal direction of the rod that is greater than the corresponding dimension of the drive square, and co-operates therewith in said longitudinal direction to determine a clearance that varies over the height of the drive square and of the assembly orifice between a value that is sufficient to allow the assembly orifice to be engaged on the drive square by moving the rod parallel to the axis of its radial finger, and a value that is very small or almost zero when the rod is in place on the drive square, said clearance being maintained during operation of the turbomachine, wherein said clearance extends at least along said longitudinal direction so that a portion of said clearance is within a plane containing said radial finger and said pin of the vane, wherein said drive square and said orifice of the rod have respective faces that contact each other and that transmit drive from the rod directly to the vane during normal operation of said device, wherein the drive is transmitted entirely and directly from the rod to the vane by said faces of said drive square and of said orifice of the rod that contact each other.