Soft in-plane and stiff out-of-plane rotor system

Patent metadata

Field	Value
Publication number	US-9656747-B2
Application number	US-201313804832-A
Country	US
Kind code	B2
Filing date	Mar 14, 2013
Priority date	Mar 14, 2013
Publication date	May 23, 2017
Grant date	May 23, 2017

Abstract

A rotor assembly includes a yoke operably associated with a rotor blade. The yoke includes a first device and a second device that attach the rotor blade to the yoke. The first device is configured to allow transverse movement of the rotor blade about a chord axis and rotational movement about a pitch-change axis. The second device is configured to allow rotational movement of the rotor blade solely about the pitch-change axis. The method includes rotating rotor assembly about a first plane of rotation, while retaining a relatively stiff out-of-plane rotation and a relatively soft in-plane rotation during flight.

First claim

What is claimed is:

1. A rotor assembly, comprising:
a yoke operably associated with a rotor blade;
a first device and a second device, both the first device and the second device being configured to attach the rotor blade to the yoke;
a spindle attached to both the first device and the second device; and
a cuff attached directly to the spindle and configured to extend at least partially around the yoke;
wherein the rotor blade attaches to the yoke via the spindle and cuff;
wherein the first device is configured to allow transverse movement of the rotor blade about a chord axis and rotational movement about a pitch-change axis;
wherein the second device is configured to allow rotational movement of the rotor blade solely about the pitch-change axis.

2. The rotor assembly of claim 1 , wherein the first device and the second device create a stiff out-of-plane rotation and a soft in-plane rotation of the rotor assembly.

3. The rotor assembly of claim 1 , the yoke comprising:
an upper arm and a lower arm that form a space therebetween;
wherein the first device and the second device are positioned within the space.

4. The rotor assembly of claim 3 , further comprising:
a first elastomeric pad and a second elastomeric pad configured to secure the first device to the upper arm and the lower arm.

5. The rotor assembly of claim 4 , wherein the first device is a radial bearing disposed between the first elastomeric pad and the second elastomeric pad.

6. The rotor assembly of claim 1 , wherein the first device is elastically attached to the yoke.

7. The rotor assembly of claim 1 , wherein the first device is a lead/lag damper.

8. The rotor assembly of claim 1 , wherein the first device is aligned with the second device about the pitch-change axis.

9. The rotor assembly of claim 1 , wherein the second device is a centrifugal damper.

10. The rotor assembly of claim 1 , further comprising:
a pitch horn attached to the spindle.

11. An aircraft, comprising:
a rotor system, having:
a first rotor assembly comprising;
a yoke operably associated with a rotor blade;
a first device and a second device, both the first device and the second device being configured to attach the rotor blade to the yoke;
a spindle attached to both the first device and the second device; and
a cuff attached directly to the spindle and configured to extend at least partially around the yoke;
wherein the rotor blade attaches to the yoke via the spindle and cuff;
wherein the first device is configured to allow transverse movement of the rotor blade about a chord axis and rotational movement about a pitch-change axis;
wherein the second device is configured to allow rotational movement of the rotor blade solely about the pitch-change axis; and
wherein the first device and the second device create the stiff out-of-plane rotation and the soft in-plane rotation of the first rotor assembly;

a second rotor assembly coaxially aligned with the first rotor assembly;

wherein the first rotor assembly and the second rotor assembly are configured to remain relatively stiff in an out-of-plane rotation plane so as to avoid contact with each other; and
wherein the first rotor assembly and the second rotor assembly are configured to remain relatively soft in an in-plane rotation plane so as to allow compensation for in-plane loads during flight.

12. The aircraft of claim 11 , further comprising:
an engine for driving the rotor system;
a transmission;
a rotor mast rotatably coupled to the transmission and operably associated with the rotor system; and
a pivot system operably associated with the transmission and configured to pivot the transmission, thereby pivoting the rotor system during flight.

13. The aircraft of claim 12 , the pivot system comprising:
a driver; and
a link system operably associated with the driver and configured to pivot the transmission.

Assignees

• Bell Helicopter Textron Inc

Inventors

• Shundo Ken
• Yuce Mithat
• Stamps Frank B

Classifications

• B64C27/35

  having elastomeric joints · CPC title

• B64C27/48

  Root attachment to rotor head · CPC title

• B64C27/322

  Blade travel limiting devices, e.g. droop stops · CPC title

• B64C27/80 Primary

  for differential adjustment of blade pitch between two or more lifting rotors · CPC title

• B64C27/51

  Damping of blade movements · CPC title