BLADE PROVIDED WITH A DRAG DAMPER, AND A ROTOR PROVIDED WITH SUCH A BLADE

• US 20100247312A1
• Filed: 03/24/2010
• Published: 09/30/2010
• Est. Priority Date: 03/27/2009
• Status: Active Grant

• Current Assignee: Airbus Helicopters
• Original Assignee: Eurocopter
• Inventors: MAZET, Stéphane, METIVIER, Rémi, EBERHARD, Alain, GIRARD, Vincent
• Granted Patent: US 8,622,703 B2
• Time in Patent Office: Days
• US Class Current: 416/134.A
• CPC Class Codes: B64C 2027/4736 from composite materials
• CPC Class Codes: B64C 27/35 having elastomeric joints
• CPC Class Codes: B64C 27/51 Damping of blade movements

Abstract

The present invention relates to a rotorcraft blade (1) provided with at least one spar (3) and an outer covering (4), said blade (1) including a hollow sleeve (10) with a wall (11) that is provided at least with said outer covering (4) secured to said spar (3). The blade includes a rotary damper (20) provided with an inner tubular strength member (21) and an outer tubular strength member (22) that are coaxial and connected together by a ring (23) of viscoelastic material, said inner tubular strength member (21) being secured to said covering (4), and said outer tubular strength member (22) being provided with a fork (25) possessing first and second tines (26, 27) facing each other so as to be suitable for receiving a first ball joint (41) close to the pitch-variation axis (AX1) of said blade (1).

Claims

1. A rotorcraft blade (1) provided with at least one spar (3) and an outer covering (4), said blade (1) having a hollow sleeve (10) with a wall (11) that is at least provided with said outer covering (4) secured to said spar (3), wherein the blade includes a rotary damper (20) provided with an inner tubular strength member (21) and an outer tubular strength member (22) that are coaxial and that are connected together by a ring (23) of viscoelastic material, said inner tubular strength member (21) being secured to said covering (4) and said outer tubular strength member (22) being provided with a fork (25) possessing first and second facing tines (26, 27), said first and second tines (26, 27) including respective first and second bores (28′

, 28″

) centered on a connection axis (AR1) so as to be suitable for receiving a first ball joint (41) close to the pitch-variation axis (AX1) of said blade (1), a first distance (DIS1) separating the connection axis (AR1) from the pitch-variation axis (AX1) of the blade being less than or equal to 10% of the chord (CO) of the blade containing said connection axis (AR1).

2. A blade according to claim 1, wherein said connection axis (AR1) intersects said pitch-variation axis (AX1).

3. A blade according to claim 1, wherein a top face (21′

) of said inner tubular strength member (21) is secured to the covering (4).

4. A blade according to claim 1, wherein, at the root (5) of said blade (1), said spar (3) is subdivided into at least two bottom tapes (31) in the pressure side (1′

) of the blade (1) and at least two top tapes (32′

, 32″

) in the suction side (1″

) of blade (1), and said inner tubular strength member (21) of said rotary damper (20) is fastened to said covering (4) between first and second top tapes (32′

, 32″

).

5. A blade according to claim 1, wherein, at the root (5) of said blade (1), said sleeve (10) includes a notch (6) in its trailing edge (10′

) in order to be suitable for receiving a connecting rod (40) carrying said first ball joint (41) for fastening between the first and second tines (26, 27) of the fork (25) of the outer tubular strength member (22).

6. A rotorcraft main rotor (7) provided with a hub (50) suitable for receiving a plurality of blades (1), said hub (50) having firstly an inner portion (51) suitable for being secured to a rotor mast (60) and secondly one arm (52) per blade (1), each arm comprising in succession an inner zone (53) secured to said inner portion (51) and possessing a cell (54), and then a peripheral zone (55), wherein said blades (1) are blades according to claim 1, each fastened to a laminated spherical abutment (70) arranged in the cell (54) of an arm (52), each blade (1) including a rotary damper (20) provided with an inner tubular strength member (21) and an outer tubular strength member (22) coaxial therewith, the inner and outer tubular strength members being connected together by a ring (23) of viscoelastic material, said outer tubular strength member (22) being provided with a fork (25) provided with first and second tines (26, 27) having respective first and second bores (28) centered on a connection axis (AR1), said rotor (7) including one connecting rod (40) per blade (1), the connecting rod having first and second ball joints (41, 42) at its first and second ends (40′

, 40″

), said first ball joint (41) of a connecting rod (40) being fastened to the first and second tines of the fork (25) of the rotary damper (20) of the associated blade close to the pitch-variation axis (AX1) of said associated blade (1), while the second ball joint (42) of the connecting rod (40) is fastened to fastener means (56) of said hub (50) on the flapping axis (AX2) of said associated blade (1), a first distance (DIS1) separating the connection axis (AR1) from the pitch-variation axis (AX1) of a blade being less than or equal to 10% of the chord (CO) of said blade containing the associated connection axis (AR1).

7. A rotor according to claim 6, wherein each fastener means (56) comprises a U-shaped branch projecting transversely from the arm (52) of the hub (50) to which the associated blade (1) is fastened.

8. A rotor according to claim 6, wherein each laminated spherical abutment (70) comprises an outer radial strength member (71) and an inner radial strength member (72) connected together by a stack (73) of rigid metal caps and of elastomer layers, said inner radial strength member (72) being secured to the peripheral zone (55) of the arm (52) associated with the hub (50), and said spar (3) of a blade (1) is connected by pins to an outer radial strength member (71) of a laminated spherical abutment (70) so that the blade (1) is fastened to the hub (50).

9. A rotor according to claim 6, wherein each connecting rod (40) presents an acute angle (α

) of less than 60 degrees relative to the pitch-variation axis (AX1) of the associated blade (1).