Vibration isolation systems for advancing blade concept rotorcraft

Patent metadata

Field	Value
Publication number	US-11214362-B2
Application number	US-201916716264-A
Country	US
Kind code	B2
Filing date	Dec 16, 2019
Priority date	Mar 15, 2017
Publication date	Jan 4, 2022
Grant date	Jan 4, 2022

Abstract

An advancing blade concept rotorcraft includes an airframe and a pylon assembly subject to vibration. The pylon assembly includes a dual rotor system having coaxially disposed top and bottom rotor assemblies that counter rotate relative to one another. The advancing blade concept rotorcraft includes a vibration isolation system including at least one pylon link coupled to the airframe and the pylon assembly. The pylon link includes a Liquid Inertia Vibration Eliminator unit operable to reduce transmission of the pylon assembly vibration to the airframe. The advancing blade concept rotorcraft includes active force generators adjacent to the pylon assembly. The active force generators include a first active force generator producing a force in a first direction and a second active force generator producing a force in a second direction to counteract multidirectional oscillations of the pylon assembly, thereby reducing vibration of the advancing blade concept rotorcraft.

First claim

What is claimed is:

1. An advancing blade concept rotorcraft comprising:
an airframe;
a pylon assembly subject to vibration, the pylon assembly including a dual rotor system having coaxially disposed top and bottom rotor assemblies that counter rotate relative to one another;
a vibration isolation system including at least one pylon link coupled to the airframe and the pylon assembly, the at least one pylon link each including a Liquid Inertia Vibration Eliminator unit operable to reduce transmission of the pylon assembly vibration to the airframe; and
a plurality of active force generators adjacent to the pylon assembly, the plurality of active force generators including a first active force generator producing a force in a first direction and a second active force generator producing a force in a second direction different from the first direction to counteract multidirectional oscillations of the pylon assembly, thereby reducing vibration of the advancing blade concept rotorcraft.

2. The advancing blade concept rotorcraft as recited in claim 1 wherein the counter rotating rotor assemblies combine harmonics in the wakes of one another to emit a dual rotor system vibration frequency; and
wherein the Liquid Inertia Vibration Eliminator unit is tuned to cancel the dual rotor system vibration frequency originating from the dual rotor system.

3. The advancing blade concept rotorcraft as recited in claim 1 wherein the pylon assembly further comprises a transmission; and
wherein the at least one pylon link is coupled to the transmission.

4. The advancing blade concept rotorcraft as recited in claim 1 wherein the Liquid Inertia Vibration Eliminator unit is a passive Liquid Inertia Vibration Eliminator unit.

5. The advancing blade concept rotorcraft as recited in claim 1 wherein the Liquid Inertia Vibration Eliminator unit is an active Liquid Inertia Vibration Eliminator unit.

6. The advancing blade concept rotorcraft as recited in claim 1 wherein the Liquid Inertia Vibration Eliminator unit includes:
first and second fluid chambers;
a tuning passage providing fluid communication between the first and second fluid chambers;
a tuning fluid moveable between the first and second fluid chambers via the tuning passage to isolate the vibration of the pylon assembly; and
a housing and a piston disposed within the housing, the piston forming the tuning passage.

7. The advancing blade concept rotorcraft as recited in claim 6 wherein the piston is operable to move within the housing such that the tuning fluid moves between the first and second fluid chambers via the tuning passage in response to the vibration of the pylon assembly.

8. The advancing blade concept rotorcraft as recited in claim 6 wherein the at least one pylon link further comprises a first portion including a first end and a second portion including a second end; and
wherein the first portion of the at least one pylon link is coupled to one of the housing or the piston and the second portion of the at least one pylon link is coupled to the other of the housing or the piston.

9. The advancing blade concept rotorcraft as recited in claim 1 wherein the at least one pylon link further comprises at least one substantially horizontal pylon link and at least one substantially vertical pylon link.

10. The advancing blade concept rotorcraft as recited in claim 1 wherein the at least one pylon link comprises a plurality of pylon links each including a respective Liquid Inertia Vibration Eliminator unit;
wherein the pylon assembly is subject to vibration in a plurality of degrees of freedom including first and second degrees of freedom; and
wherein the plurality of pylon links include first and second pylon links, the first pylon link oriented to isolate vibration of the pylon assembly in the first degree of freedom, the second pylon link oriented to isolate vibration of the pylon assembly in the second degree of freedom.

11. The advancing blade concept rotorcraft as recited in claim 10 wherein the plurality of pylon links further comprise a plurality of substantially horizontal pylon links circumferentially disposed around the pylon assembly and a plurality of substantially vertical pylon links circumferentially disposed around the pylon assembly.

12. The advancing blade concept rotorcraft as recited in claim 11 wherein the plurality of vertical pylon links are circumferentially equidistant from one another.

13. The advancing blade concept rotorcraft as recited in claim 11 wherein the plurality of pylon links further comprise pairs of substantially horizontal pylon links and substantially vertical pylon links, each pair of horizontal and vertical pylon links forming an angle between 70 and 110 degrees.

14. The advancing blade concept rotorcraft as recited in claim 11 wherein at least one of the horizontal pylon links is angularly offset from a horizontal plane.

15. The advancing blade concept rotorcraft as recited in claim 1 wherein the at least one pylon link further comprises a torque restraint and fore/aft vibration isolation subsystem.

16. The advancing blade concept rotorcraft as recited in claim 1 wherein the plurality of active force generators are coupled to the airframe.

17. The advancing blade concept rotorcraft as recited in claim 1 wherein the plurality of active force generators include at least one rotary active force generator.

18. The advancing blade concept rotorcraft as recited in claim 1 wherein the first active force generator produces a force in a vertical direction, the second active force generator produces a force in a longitudinal direction and a third active force generator produces a force in a lateral direction to produce forces to counteract the multidirectional oscillations of the pylon assembly, thereby reducing vibration of the advancing blade concept rotorcraft.

19. The advancing blade concept rotorcraft as recited in claim 1 further comprising:
a pusher propeller having variable pitch blades configured to propel the advancing blade concept rotorcraft in a forward direction; and
a flight control system having a fly-by-wire architecture;
wherein the top and bottom rotor assemblies are rigid rotor assemblies;
wherein the top and bottom rotor assemblies are variable speed rotor assemblies; and
wherein the top and bottom rotor assemblies each include four rotor blades.

20. The advancing blade concept rotorcraft as recited in claim 1 further comprising a tailboom including a downward fin and a horizontal stabilizer.

Assignees

• Textron Innovations Inc

Inventors

• Foskey Christopher Edward
• Stamps Frank Bradley
• Smith Michael Reaugh

Classifications

• B64U10/13

  Flying platforms · CPC title

• B64C27/10

  arranged coaxially · CPC title

• B64C2027/002

  mounted between the rotor drive and the fuselage · CPC title

• B64C2027/8236

  including pusher propellers · CPC title

• B64C27/001 Primary

  Vibration damping devices · CPC title