Linear electro-mechanical actuator

1. A linear electro-mechanical actuator, comprising:

a containment structure ( 2 );

a pusher ( 8 ) designed to translate relative to the containment structure ( 2 ) in such a way that it at least partly comes out of the containment structure ( 2 ) during actuator ( 1 ) operation;

a nut ( 5 ) located in the containment structure ( 2 ) and able to rotate about an axis (X) driven by a driving force;

a screw shaft ( 6 ) inserted in the nut ( 5 ) and connected to the pusher ( 8 ), said screw shaft ( 6 ) being interconnected with the nut ( 5 ) by means of a helical recirculating ball coupling in such a way that a rotation of the nut ( 5 ) causes a translation of the screw shaft ( 6 ) along said axis (X);

an anti-rotation mechanism ( 9 ) acting on the screw shaft ( 6 ) to prevent the screw shaft ( 6 ) from rotating about said axis (X);

wherein said screw shaft ( 6 ) comprises a cavity ( 7 ) positioned about the axis (X) and wherein said anti-rotation mechanism ( 9 ) comprises a guide unit ( 10 ) fixed to the containment structure ( 2 ) and inserted in said cavity ( 7 ) in the screw shaft ( 6 ), said guide unit ( 10 ) being coupled in a non-rotational fashion to the screw shaft ( 6 );

wherein said guide unit ( 10 ) is coupled in a non-rotational fashion to the screw shaft ( 6 ) by means of a recirculating ball coupling (R) designed to allow a translation of the screw shaft ( 6 ) relative to the guide unit ( 10 ) along the axis (X), and wherein the recirculating ball coupling (R) extends on a closed path comprising a first stretch (R 1 ) parallel with the axis (X) and interposed between the guide unit ( 9 ) and the screw shaft ( 6 ), for forming a sliding coupling between the guide unit ( 9 ) and the screw shaft ( 6 ), and a second stretch (R 2 ) made inside the guide unit ( 9 ) for the recirculation of the balls, and a pair of third stretches (R 3 ) connecting the first and second stretches (R 1 , R 2 ),

characterised in that the guide unit ( 10 ) comprises:

a first portion ( 10 a ) fixed to the containment structure ( 2 );

a second portion ( 10 b ) removably connected to the first portion ( 10 a ) and comprising longitudinal outer grooves ( 12 ), forming said first stretch (R 1 ) of the closed path, and inner channels ( 13 ) for recirculation of the balls forming the second stretch (R 2 ) of the closed path; and

a third portion ( 10 c ) removably fixed to the second portion ( 10 b );

and wherein the first and third portions ( 10 a , 10 c ) comprise, on a respective interface with the second portion ( 10 b ), diverter elements ( 14 ) for conveying the balls between each inner channel ( 13 ) and a respective longitudinal outer groove ( 12 ).

2. The actuator according to claim 1 , wherein the containment structure ( 2 ) comprises a supporting flange ( 11 ) positioned transversally to the axis (X) and wherein the guide unit ( 10 ) is fixed cantilever-style to the supporting flange ( 11 ).

3. The actuator according to claim 1 , wherein the first portion ( 10 a ) of the guide unit ( 10 ) has substantially cylindrical extension and, in at least one operating configuration of the actuator ( 1 ), is inserted in the cavity ( 7 ) in the screw shaft ( 6 ).

4. The actuator according to claim 1 , wherein the guide unit ( 10 ) extends along an axis coinciding with the axis (X) of rotation of the nut ( 5 ).

5. The actuator according to claim 1 , also comprising an electric motor comprising a stator ( 3 ) fixed to the containment structure ( 2 ) and a rotor ( 4 ) fixed to the nut ( 5 ); the recirculating ball coupling (R) being positioned axially along the axis (X) of the nut ( 5 ) in a position enclosed within an axial dimension of the stator ( 3 ), preferably centred relative to the stator ( 3 ).

6. The actuator according to claim 1 , wherein the outside of the screw shaft ( 6 ) comprises a helical groove ( 6 a ) for connection with the nut ( 5 ), and wherein, in at least one operating configuration, said recirculating ball coupling (R) comprises a longitudinal dimension, along the axis (X), which is partly superposed by a longitudinal extension of the helical groove ( 6 a ).

7. The actuator according to claim 1 , wherein the inside of the screw shaft ( 6 ) comprises a plurality of longitudinal grooves ( 15 ) whose length, along the axis (X) of the nut ( 5 ), is greater than a corresponding length of the second portion ( 10 b ) of the guide unit ( 10 ).

8. The actuator according to claim 2 , wherein the guide unit ( 10 ) extends along an axis coinciding with the axis (X) of rotation of the nut ( 5 ).

9. The actuator according to claim 3 , wherein the guide unit ( 10 ) extends along an axis coinciding with the axis (X) of rotation of the nut ( 5 ).