Simplified system for controlling propeller blade pitch in an aircraft turboshaft engine

1. 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.

2. A system for controlling according to claim 1 , further comprising means for elastic return coupled to the actuating member, and making it possible, when the actuating member is not subjected to the actuating torque, to displace in rotation the actuating member relatively to the first track, to bring back the locking member into the normal over-center position.

3. A system for controlling according to claim 1 , wherein the first track is arranged exteriorly in relation to the second track.

4. A system for controlling according to claim 1 , wherein the second track is arranged exteriorly in relation to the first track.

5. A system for controlling according to claim 1 , further comprising an actuating motor controlling in rotation the actuating member.

6. A system for controlling according to claim 1 , wherein the locking member includes a roller, and the surfaces with which it cooperates are substantially flat surfaces.

7. A system for controlling according to claim 1 , wherein the locking member includes a ball, and the surfaces with which it cooperates are substantially spherical surfaces.

8. A system for controlling according to claim 1 , comprising plural locking members angularly spaced from one another around the axis of the first and second tracks, each housed in its own recessed angular portion of the member for actuating, and in its own notch of the first track.

9. A system for controlling according to claim 1 , to control a single blade of the propeller of the turboshaft engine.

10. A system for controlling according to claim 1 , to simultaneously control a plurality of blades of the propeller of the turboshaft engine.

11. A system for controlling according to claim 10 , further comprising a sliding member configured to cooperate with the blades such that its displacement leads the blades to come closer/move away from the minimum incidence position, the sliding member being controlled by rotating means of control making it possible to transform their rotating movement into a sliding movement of the member, the rotating means of control being integral in rotation with the first track.

12. A method for controlling a system for controlling propeller blade pitch in a turboshaft engine according to claim 1 , wherein when a setting of the incidence is required, a suitable actuating torque is applied to the member for actuating.

13. A propeller for an aircraft turboshaft engine comprising at least one system for controlling the blade pitch according to claim 1 .

14. A propeller according to claim 13 , further comprising a propeller rotor configured to rotate around a longitudinal axis of the propeller in relation to a stator, and carrying blades,

the propeller further comprising the system for controlling the pitch of the blades, making it possible to displace the blades between a minimum incidence position and a maximum incidence position,

the system for controlling the pitch comprising a sliding member according to the longitudinal axis, cooperating with the blades such that its displacement drives the blades to come closer/move away from their minimum incidence position, the sliding member being controlled by rotating means for actuating making it possible to transform their rotating movement around the longitudinal axis into a sliding movement of the member according to the same axis, the rotating means for control being integral in rotation with the first track and the second track being integral in rotation with a drive shaft carrying the propeller rotor,

the system for controlling the pitch further comprising an actuating motor to apply the rotating movement to the rotating means for actuating, by being connected to the member for actuating.

15. A propeller according to claim 14 , wherein the rotating means for actuating comprises a ball screw.

16. A propeller according to claim 14 , wherein the sliding member comprises a sliding cone cooperating with an off-centered finger of each of the blades being associated with it.

17. A turbomachine for an aircraft comprising at least one propeller according to claim 13 .