Actuating assembly for a thrust reverser of an aircraft engine
An actuating assembly for an aircraft engine thrust reverser includes a drive shaft bearing a master pinion; a ball screw bearing a slave pinion engaging with the master pinion; a nut capable of translating over the ball screw as a result of the rotation of the ball screw; an extension tube rigidly secured to the nut and a lock assembly to block the rotation of the drive shaft in a so-called direct jet position of the reverser. The extension tube includes, at its free end, a member for connecting to a portion of the reverser prior to being actuated. In particular, the lock assembly includes an abutment secured to the drive shaft, and a cotter moveable between a locking position and an unlocking position. The reduction ratio (R) between the slave and master pinions is even.
1. An actuating assembly for an aircraft engine thrust reverser, comprising:
a drive shaft bearing a master pinion;
a ball screw bearing a slave pinion engaging with said master pinion;
a nut translating over the ball screw as a result of the rotation thereof;
an extension tube secured to said nut, the extension tube comprising, at a free end thereof, an eyelet for connecting to a clevis of said reverser to be actuated; and
locking means for blocking a rotation of said drive shaft, capable of immobilizing said portion in a closed position of the reverser,
wherein said locking means comprise an abutment secured to said drive shaft, and a cotter movable between a locking position in which it prevents a rotation of said abutment, and an unlocking position in which it allows the rotation of said abutment,
wherein a reduction ratio (R) between said slave pinion and said master pinion is even, such that:
when said extension tube is in a fully retracted position and said eyelet is correctly oriented with respect to said clevis, said drive shaft and said abutment are in a reference position in which said abutment is in contact with said cotter in locked position, and
said abutment always reaches said reference position after a full or half rotation of said extension tube during maintenance operations.
2. The actuating assembly according to claim 1 , wherein the locking of said abutment by said cotter is effective including when the portion of said reverser to be actuated is set apart from a direct jet position by a predetermined distance (J).
3. The actuating assembly according to claim 2 , wherein said predetermined distance (J) is of the magnitude of 2 millimeters.
4. The actuating assembly according to claim 2 , wherein features of said actuating assembly are selected such that:
( J/P )* R <(1 −X ),
where: J is the predetermined distance;
P is a pitch of the ball screw;
R is the reduction ratio between said slave pinion and said master pinion; and
X is a positive real number within the interval [0, 1], representing a ratio between a cumulative circumferential length of said abutment and said cotter, and the length of the associated total circumference.
5. A thrust reverser for a turbojet engine, wherein it comprises at least an actuating assembly in accordance with claim 1 .
6. A nacelle for a turbojet engine, wherein it comprises a thrust reverser in accordance with claim 5 .