Rotorcraft centrifugal force bearing

Patent metadata

Field	Value
Publication number	US-10864985-B2
Application number	US-201715659272-A
Country	US
Kind code	B2
Filing date	Jul 25, 2017
Priority date	Jul 25, 2017
Publication date	Dec 15, 2020
Grant date	Dec 15, 2020

Abstract

A centrifugal force (CF) bearing for a rotorcraft rotor assembly includes an inner-member, an outer-member, and an elastic member interposed between the inner- and outer-members. The inner-member includes a boss configured for location to and engagement with a yoke. The boss includes a tapered profile (e.g., conic) portion. A tapered recess region of the yoke includes a profile that is substantially matched to receive and contact the tapered profile of the boss. The CF bearing is configured for attachment to a grip of the rotor assembly. The boss is configured to communicate mechanical loads (e.g., centrifugal force, lateral shear, vertical shear) from the grip to the yoke during operation of the rotor assembly.

First claim

What is claimed is:

1. A device, comprising:
a centrifugal force (CF) bearing for a rotorcraft, the CF bearing comprising:
a first member configured for contacting engagement with an inner surface of a rotor grip;
a second member configured for engagement with a rotor yoke, and a third member, the third member interposed between the first member and the second member, wherein:
the second member comprises:
a rigid plate;
a first protruding feature that extends outward from a first surface of the rigid plate and in a direction toward the first member, the first protruding feature fitting within a recess in the third member and in contacting engagement with a surface of the third member that defines the recess;

a second protruding feature that extends outward from a second surface of the rigid plate and in a direction away from the third member;
the second protruding feature comprises a tapered profile with straight sidewalls, the taper extending linearly and continuously from the second surface of the rigid plate to the outermost end of the second protruding feature; and
wherein the rigid plate includes a first rigid extension at one end of the rigid plate and a second rigid extension at an opposite end of the rigid plate.

2. The device of claim 1 , wherein the second protruding feature comprises a conical boss.

3. The device of claim 2 , wherein:
the third member comprises an elastic material; and
the CF bearing is configured to communicate a mechanical load from the rotor grip through the conical boss to the rotor yoke.

4. The device of claim 3 , wherein the tapered profile is matched for positive engagement of the conical boss in a tapered recess of the rotor yoke.

5. The device of claim 3 , wherein:
the rotor grip is one of a main rotor grip, a tail rotor grip, a prop-rotor grip, a tandem rotor grip, or a coaxial rotor grip; and
the rotor yoke is a corresponding one of a main rotor yoke, a tail rotor yoke, a prop-rotor yoke, a tandem rotor yoke, or a coaxial rotor yoke.

6. The device of claim 1 , wherein:
the first member comprises at least one of steel or titanium;
the second member comprises 6Al-4V titanium; and
the third member comprises an elastomeric material.

7. The device of claim 1 , wherein the first rigid extension has a uniform thickness extending from the outermost periphery of the second member to an interface between the first rigid extension and the first protruding feature, the interface being offset from the outermost periphery of the second member, wherein the uniform thickness is measured between the first surface of the rigid plate and the second surface of the rigid plate.

8. The device of claim 1 , wherein the rigid plate has a first diameter at a widest point of the rigid plate and the second protruding feature has a second diameter at a widest point of the second protruding feature, the first diameter being greater than the second diameter.

9. A system, comprising:
a rotor assembly comprising:
a yoke coupled to a rotating mast and having a tapered recess;
a grip configured for attachment to a rotor blade, the grip extending through an opening in the yoke; and
a centrifugal force (CF) bearing, wherein:
the CF bearing comprises an inner-member, an outer-member, and an elastic member interposed between the inner-member and the outer-member;
the outer-member is attached to a portion of the grip;
the inner-member comprises a first surface and a second surface, the second surface opposing the first surface;
the first surface comprises a protrusion that extends in a direction toward the outer-member, the protrusion having a profile that is curvilinear;
the second surface comprises a planar external surface and a boss that protrudes from the planar external surface in a direction away from the elastic member; and
the boss has a profile that is continuously and linearly tapered from the planar external surface to an outermost end of the boss and further wherein the outermost periphery of the boss is radially displaced inward of the outermost periphery of the planar external surface, wherein the boss is disposed in and matches a profile of the tapered recess of the yoke.

10. The system of claim 9 , wherein the outer-member is attached to the grip with an outer-clamp.

11. The system of claim 10 , wherein the boss is located to the yoke by attachment of the inner-member to an inner-clamp, the inner clamp engaging with an outer surface of the yoke.

12. The system of claim 9 , wherein the continuously and linearly tapered profile is tapered in a direction away from the elastic member.

13. The system of claim 12 , wherein the continuously and linearly tapered profile is matched to a tapered profile of the tapered recess of the yoke.

14. The system of claim 9 , wherein:
the CF bearing is configured to communicate a mechanical load from the grip through the boss to the yoke; and
the elastic member is configured to communicate the mechanical load between the outer-member and the inner-member.

15. The system of claim 14 , wherein the mechanical load comprises at least one of centrifugal force, lateral shear, or vertical shear.

16. The system of claim 9 , wherein the rotor assembly is a main rotor assembly.

17. The system of claim 9 , wherein:
the outer-member comprises a first metal;
the elastic member comprises an elastomeric material; and
the inner-member comprises a second metal.

18. The system of claim 17 , wherein:
the first metal comprises steel or titanium;
the elastomeric material comprises vulcanized rubber; and
the second metal comprises 6Al-4V titanium.

19. A method, comprising:
operating a rotorcraft having a main rotor assembly and an articulated main rotor blade, by
receiving a pilot control input; and
in response to the pilot control input, changing a configuration of a main rotor assembly of the rotorcraft;
wherein the main rotor assembly of the rotorcraft comprises:
a grip that is attached to an articulated main rotor blade; and
a yoke that has a tapered recess, the tapered recess having a first diameter at the mouth of the tapered recess and a second diameter less than the first diameter at the bottom of the tapered recess, and an intermediate diameter along sidewalls of the tapered recess, the sidewalls being straight from the mouth of the tapered recess to the bottom of the tapered recess; and

mechanically communicating a mechanical load from the grip to the yoke through a centrifugal force (CF) bearing that is interposed between the grip and the yoke, wherein:
the CF bearing has an inner-member, an outer-member, and an elastic member interposed between the inner-member and the outer-member;
the outer-member is attached to the grip by a first clamp;
the inner-member is engaged to the yoke by a second clamp, and wherein the inner-member includes
a rigid plate having a first rigid extension at one end of the rigid plate and a second rigid extension at an opposite end of the rigid plate,
a protruding feature that extends outward from a first surface of the rigid plate, and
a boss that extends away from the elastic member and outward from a second surface of the rigid plate, the boss having a tapered profile that is matched to and disposed in the tapered recess of the yoke, the taper extending continuously and with a fixed slope from the second surface of the rigid plate to the outermost end of the boss.

20. The method of claim 19 , wherein the main rotor assembly further comprises
a plurality of grips attached to

Assignees

• Textron Innovations Inc

Inventors

• Mccullough John
• Wiinikka Mark Adam
• Ledbetter Matthew Curtis

Classifications

• B64C27/39 Primary

  with individually articulated blades, i.e. with flapping or drag hinges · CPC title

• B64C27/35

  having elastomeric joints · CPC title

• B64C27/48

  Root attachment to rotor head · CPC title