Aircraft seat

1. An aircraft seat comprising at least one actuator configured to generate movement and at least one movement transmission device, the transmission device comprising:

a support;

a frame that is fixed relative to the support, said frame being provided with an immobilizing portion,

a drive shaft driven by the actuator to rotate about an axis of rotation,

a gear wheel provided with coupling teeth having inclined side walls, said gear wheel being freely rotatable relative to the drive shaft;

a sleeve slidably mounted on the drive shaft and integral in rotation with the drive shaft, the sleeve comprising a complementary immobilizing portion configured to couple with the immobilizing portion of the frame as well as coupling teeth having inclined side walls configured to couple with the coupling teeth of the gear wheel; and

an elastic member configured to push the sleeve along an axial direction towards the gear wheel to couple the sleeve to the gear wheel; the elastic member having a stiffness; the stiffness of the elastic member and the inclination of the side walls of the coupling teeth of the gear wheel and of the coupling teeth of the sleeve being chosen such that, when a torque greater than a threshold torque is applied to the gear wheel, the sleeve slides on the drive shaft from a driving position in which the sleeve is coupled to the gear wheel, to an immobilizing position in which the immobilizing portion of the frame is coupled to the complementary immobilizing portion of the sleeve.

2. The aircraft seat according to claim 1 , wherein the side walls of the coupling teeth of the sleeve form an angle of between 8° and 30° relative to the axis of rotation, and wherein the elastic member has a stiffness of between 2 daN/mm and 15 daN/mm.

3. The aircraft seat according to claim 1 , wherein the immobilizing portion comprises grooves extending over a first circular arc, and wherein the complementary immobilizing portion comprises projections extending over a second circular arc, the second circular arc being smaller than the first circular arc.

4. The aircraft seat according to claim 3 , wherein a height of the coupling teeth of the gear wheel and/or a height of the coupling teeth of the sleeve is greater than a height of the projections of the immobilizing portion and/or a height of the projections of the complementary immobilizing portion.

5. The aircraft seat according to claim 1 , wherein a first end of the frame comprises a counterbore, and wherein the sleeve comprises a housing arranged facing the counterbore of the frame; and wherein the elastic member is arranged around the drive shaft and housed partly in the counterbore of the sleeve and partly in the housing of the sleeve.

6. The aircraft seat according to claim 1 , wherein an internal face of the sleeve and an external face of the drive shaft comprise a slide connection extending along the direction of the axis of rotation.

7. The aircraft seat according to claim 6 , wherein one of the internal face of the sleeve and the external face of the drive shaft comprises a groove extending along the direction of the axis of rotation, and the other comprises a recess and a pin that is housed in the recess and configured to slide in the groove.

8. The aircraft seat according to claim 1 , wherein the transmission device comprises a first stop arranged on the drive shaft, and a second stop arranged on the drive shaft at a predefined distance from the first stop, wherein the gear wheel, the sleeve, the elastic member, and the frame are fitted onto the drive shaft between the first stop and the second stop.

9. The aircraft seat according to claim 8 , wherein the first stop comprises a peripheral groove formed on the outer face of the drive shaft, and a stop ring embedded in the peripheral groove.