Loop yoke for proprotor systems

• US 10,518,867 B2
• Filed: 12/12/2016
• Issued: 12/31/2019
• Est. Priority Date: 12/12/2016
• Status: Active Grant

• Current Assignee: Textron Innovations Incorporated (Textron Inc)
• Original Assignee: Textron Innovations Incorporated (Textron Inc)
• Inventors: Parham, Jr., Thomas Clement, Choi, Jouyoung Jason, Miller, Gary, Stamps, Frank Bradley, Rauber, Richard Erler
• Primary Examiner(s): Green, Richard R.
• Assistant Examiner(s): Shur, Steven J
• Application Number:
  US15/375,356
• Publication Number:
  US 20180162518A1
• Time in Patent Office: 1,114 Days
• CPC Class Codes: B29C 70/30 Shaping by lay-up, i.e. applying fibres, tape or broadsheet on a mould, former or core; Shaping by spray-up, i.e. spraying of fibres on a mould, former or core
• CPC Class Codes: B29C 70/32 on a rotating mould, former or core
• CPC Class Codes: B29K 2105/0881 unidirectional
• CPC Class Codes: B29K 2307/04 Carbon
• CPC Class Codes: B29L 2031/3088 Helicopters
• CPC Class Codes: B64C 11/04 Blade mountings
• CPC Class Codes: B64C 11/06 for variable-pitch blades
• CPC Class Codes: B64C 27/00 Rotorcraft; Rotors peculiar thereto
• CPC Class Codes: B64C 27/33 having flexing arms
• CPC Class Codes: B64C 27/35 having elastomeric joints
• CPC Class Codes: B64C 27/51 Damping of blade movements
• CPC Class Codes: B64C 27/54 Mechanisms for controlling blade adjustment or movement relative to rotor head, e.g. lag-lead movement
• CPC Class Codes: B64C 29/00 Aircraft capable of landing or taking-off vertically, e.g. vertical take-off and landing [VTOL] aircraft rotorcraft B64C27/00
• CPC Class Codes: B64C 29/0033 the propellers being tiltable relative to the fuselage

Abstract

A yoke for providing a centrifugal force retention load path between a proprotor blade and a hub of a soft-in-plane proprotor system operable for use on a tiltrotor aircraft. The yoke includes a continuous loop having a longitudinal axis and first and second longitudinal sections extending between inboard and outboard arcuate sections. A flapping bearing receiving region is disposed at least partially within the inboard arcuate section to an interior of the continuous loop. A centrifugal force bearing receiving region is disposed at least partially within the outboard arcuate section to the interior of the continuous loop. The continuous loop is formed from a composite material having a plurality of double bias material plies and a plurality of unidirectional material plies such that the number of unidirectional material plies is greater than the number of double bias material plies.

Claims

1. A soft-in-plane proprotor system operable for use on a tiltrotor aircraft, the proprotor system comprising:

a hub;

a plurality of proprotor blades coupled to the hub such that each proprotor blade is operable to independently flap relative to the hub about a flapping axis, independently change pitch about a pitch change axis and independently oscillate in-plane about a lead-lag axis;

a plurality of loop yokes, each coupling one of the proprotor blades with the hub and each including;

a continuous loop having first and second longitudinal sections extending between inboard and outboard arcuate sections;

a flapping bearing receiving region disposed at least partially within the inboard arcuate section to an interior of the continuous loop; and

a centrifugal force bearing receiving region disposed at least partially within the outboard arcuate section to the interior of the continuous loop; and

a plurality of bearing assemblies, each disposed within one of the continuous loops and each including;

a flapping bearing received by the flapping bearing receiving region of the respective continuous loop and coupled to the hub;

a lead-lag damper coupled to the hub;

a centrifugal force bearing received by the centrifugal force bearing receiving region of the respective continuous loop; and

a blade anchor positioned between the lead-lag damper and the centrifugal force bearing, the blade anchor coupled to the respective proprotor blade between the lead-lag damper and the centrifugal force bearing such that the respective lead-lag axis is disposed within the respective proprotor blade;

wherein, each of the continuous loops comprises a composite material having a plurality of double bias material plies and a plurality of unidirectional material plies; and

wherein, the number of unidirectional material plies is greater than the number of double bias material plies.

2. The proprotor system as recited in claim 1 wherein the composite material of each of the continuous loops further comprises at least two of the unidirectional material plies interposed between the double bias material plies.

3. The proprotor system as recited in claim 1 wherein the composite material of each of the continuous loops further comprises a ratio of unidirectional material plies to double bias material plies between about 2 to 1 and about 6 to 1.

4. The proprotor system as recited in claim 1 wherein the composite material of each of the continuous loops further comprises a ratio of unidirectional material plies to double bias material plies between about 3 to 1 and about 5 to 1.

5. The proprotor system as recited in claim 1 wherein the composite material of each of the continuous loops further comprises a ratio of unidirectional material plies to double bias material plies of about 4 to 1.

6. The proprotor system as recited in claim 1 wherein the double bias material plies of the composite material of each of the continuous loops further comprise double bias carbon fiber fabric.

7. The proprotor system as recited in claim 1 wherein the double bias material plies of the composite material of each of the continuous loops further comprise double bias carbon fiber fabric with plus and minus 45 degree orientation relative to a longitudinal axis of the respective continuous loop.

8. The proprotor system as recited in claim 1 wherein the unidirectional material plies of the composite material of each of the continuous loops further comprise unidirectional carbon fiber fabric.

9. The proprotor system as recited in claim 1 wherein the unidirectional material plies of the composite material of each of the continuous loops further comprise unidirectional carbon fiber fabric with 0 degree orientation parallel to a longitudinal axis of the respective continuous loop.

10. The proprotor system as recited in claim 1 wherein the first and second longitudinal sections of each of the continuous loops are generally parallel to one another.

11. The proprotor system as recited in claim 1 wherein the first and second longitudinal sections of each of the continuous loops are tapered between the inboard arcuate section and the outboard arcuate section.

12. A tiltrotor aircraft, comprising:

a fuselage;

a wing extending from the fuselage;

at least one drive system supported by at least one of the fuselage and the wing; and

at least one soft-in-plane proprotor system coupled to the drive system, the proprotor system including;

a hub;

a plurality of proprotor blades coupled to the hub such that each proprotor blade is operable to independently flap relative to the hub about a flapping axis, independently change pitch about a pitch change axis and independently oscillate in-plane about a lead-lag axis;

a plurality of loop yokes, each coupling one of the proprotor blades with the hub and each including;

a continuous loop having first and second longitudinal sections extending between inboard and outboard arcuate sections;

a flapping bearing receiving region disposed at least partially within the inboard arcuate section to an interior of the continuous loop; and

a centrifugal force bearing receiving region disposed at least partially within the outboard arcuate section to the interior of the continuous loop; and

a plurality of bearing assemblies, each disposed within one of the continuous loops and each including;

a flapping bearing received by the flapping bearing receiving region of the respective continuous loop and coupled to the hub;

a lead-lag damper coupled to the hub;

a centrifugal force bearing received by the centrifugal force bearing receiving region of the respective continuous loop; and

a blade anchor positioned between the lead-lag damper and the centrifugal force bearing, the blade anchor coupled to the respective proprotor blade between the lead-lag damper and the centrifugal force bearing such that the respective lead-lag axis is disposed within the respective proprotor blade;

wherein, each of the continuous loops comprises a composite material having a plurality of double bias material plies and a plurality of unidirectional material plies; and

wherein, the number of unidirectional material plies is greater than the number of double bias material plies.

13. The tiltrotor aircraft as recited in claim 12 wherein the composite material of each of the continuous loops further comprises at least two of the unidirectional material plies interposed between the double bias material plies.

14. The tiltrotor aircraft as recited in claim 12 wherein the composite material of each of the continuous loops further comprises a ratio of unidirectional material plies to double bias material plies between about 2 to 1 and about 6 to 1.

15. The tiltrotor aircraft as recited in claim 12 wherein the composite material of each of the continuous loops further comprises a ratio of unidirectional material plies to double bias material plies between about 3 to 1 and about 5 to 1.

16. The tiltrotor aircraft as recited in claim 12 wherein the composite material of each of the continuous loops further comprises a ratio of unidirectional material plies to double bias material plies of about 4 to 1.

17. The tiltrotor aircraft as recited in claim 12 wherein the double bias material plies of the composite material of each of the continuous loops further comprise double bias carbon fiber fabric.

18. The tiltrotor aircraft as recited in claim 12 wherein the double bias material plies of the composite material of each of the continuous loops further comprise double bias carbon fiber fabric with plus and minus 45 degree orientation relative to a longitudinal axis of the respective continuous loop.

19. The tiltrotor aircraft as recited in claim 12 wherein the unidirectional material plies of the composite material of each of the continuous loops further comprise unidirectional carbon fiber fabric.

20. The tiltrotor aircraft as recited in claim 12 wherein the unidirectional material plies of the composite material of each of the continuous loops further comprise unidirectional carbon fiber fabric with 0 degree orientation parallel to a longitudinal axis of the respective continuous loop.