Rotor assembly for an aircraft capable of hovering and equipped with an improved constraint assembly
A constraint assembly for an aircraft, having a first member; a second member mounted to translate along and rotate about its own axis; and connecting means for connecting the first and second member, to prevent rotation of the second member about the axis with respect to the first member; the connecting means having a retaining arm, which projects outwards from one of the first and second member, and extends at a distance of other than zero from the axis; and an antirotation bracket, which projects from the other of the first and second member, extends at a distance of other than zero from the axis, and defines a through opening engaged in sliding manner by the retaining arm.
1. A rotor assembly ( 10 ) for an aircraft ( 1 ) capable of hovering, said rotor assembly ( 10 ) having an axis (A) and comprising:
a supporting member ( 8 ) coaxial with said axis (A);
a drive shaft ( 5 ) extending coaxially through said supporting member ( 8 ) and fitted to the supporting member ( 8 ) in an axially fixed position and so as to rotate about said axis (A);
a movable member ( 20 ) mounted so as to be able to translate along and rotate about said axis (A);
an oscillating-plate assembly ( 12 ), which is coaxial with said axis (A), is fitted to said movable member ( 20 ) to oscillate with respect to it about transverse axes substantially perpendicular to said axis (A), and in turn comprises a first annular member ( 13 ) angularly fixed to said movable member ( 20 ), and a second annular member ( 15 ) which rotates on said first annular member ( 13 ) together with said drive shaft ( 5 );
supporting and actuating means ( 23 ), which cooperate with said first annular member ( 13 ) to move said oscillating-plate assembly ( 12 ) and said movable member ( 20 ) jointly along said axis (A) with respect to said supporting member ( 8 ), and to oscillate said oscillating-plate assembly ( 12 ) about said transverse axes with respect to said movable member ( 20 ); and
connecting means ( 39 ) for connecting said supporting member ( 8 ) and said movable member ( 20 ), to prevent rotation of said movable member ( 20 ) about said axis (A) with respect to said supporting member ( 8 );
characterized in that said connecting means ( 39 ) comprise:
a retaining arm ( 41 ) projecting outwards from one ( 20 ) of said supporting member ( 8 ) and said movable member ( 20 ), and extending at a distance of other than zero from said axis (a); and
an antirotation bracket ( 42 ), which projects from the other ( 8 ) of said supporting member ( 8 ) and said movable member ( 20 ), extends at a distance of other than zero from said axis (A), and defines a through opening ( 43 ) engaged in sliding manner by said retaining arm ( 41 ).
2. A rotor assembly as claimed in claim 1 , wherein said retaining arm ( 41 ) fully extends in a longitudinal direction (B) sloping with respect to said axis (A), and slides inside said opening ( 43 ) in said antirotation bracket ( 42 ) in a movement parallel to said axis (A).
3. A rotor assembly as claimed in claim 2 , wherein said longitudinal direction (B) allows said retaining arm ( 41 ) to engage and disengage said opening ( 43 ) in said antirotation bracket ( 42 ).
4. A rotor assembly as claimed in claim 2 , wherein said retaining arm ( 41 ) engages said opening ( 43 ) in said antirotation bracket loosely in a direction parallel to said axis (A).
5. A rotor assembly as claimed in claim 1 , wherein said opening ( 43 ) has a prismatic profile.
6. A rotor assembly as claimed in claim 1 , wherein said antirotation bracket ( 42 ) is fixed to said supporting member ( 8 ); and said retaining arm ( 41 ) is fixed to said movable member ( 20 ).
7. A rotor assembly as claimed in claim 6 , wherein said retaining arm ( 41 ) is fixed rigidly to said movable member ( 20 ).
8. A rotor assembly as claimed in claim 1 , wherein said retaining arm ( 41 ) is covered with antifriction material.