Patent ID: 8608440

Claim:
A system controlling blade pitch of a propeller of a turboshaft engine for an aircraft, comprising: a substantially annular first track configured to be connected to at least one propeller blade, and of which its rotation is configured to provide for setting of incidence of the blade, the first track including at least one notch delimited by two surfaces; a second substantially annular track, concentric to the first track; an actuating member that actuates the first track, substantially annular, arranged between the first and second tracks and concentric to the second tracks, the actuating member including at least one recessed angular portion delimited by two surfaces at a distance from one another; and at least one locking member provided between the first and second tracks, housed in the recessed angular portion of the actuating member, and in the notch of the first track, the locking member to occupy, during operation of the turboshaft engine: a normal over-center position, in contact with the second track by being arranged between the two surfaces of the actuating member, at a distance from the actuating member, and in contact with the notch, wherein aerodynamic force exerted on the blade of the propeller in rotation generates a torque of a given direction on the first track by causing a first contact force, on the locking member, of that of two surfaces of the notch located farthest upstream in a given direction of the torque, and generating a reaction force of the second track on the locking member, the first contact force and the reaction force providing an over-centering of the first and second tracks, rendering the second tracks integral in rotation; and a release position, wherein the locking member is in contact with the surface of the notch farthest upstream, and also with one of the two surfaces of the actuating member, the release position being provided by application of an actuating torque on the actuating member, of a value making it possible to exert, on the locking member with the surface concerned, a second bearing force that is sufficient to render null the reaction force of the second track on the locking member, and as such break the over-centering, the release position authorizing displacement in rotation, in relation to the second track, according to the direction of the actuating torque, of a unit comprising the first track, the locking member, and the actuating member.