ROTORCRAFT VIBRATION ISOLATION SYSTEMS

• US 20150308534A1
• Filed: 04/23/2014
• Published: 10/29/2015
• Est. Priority Date: 04/23/2014
• Status: Active Grant

• Current Assignee: Bell Helicopter Textron Incorporated (Textron Inc)
• Original Assignee: Bell Helicopter Textron Incorporated (Textron Inc)
• Inventors: Smith, Michael, Stamps, Frank Bradley, Lee, Taeoh, Heverly, David E. II
• Granted Patent: US 9,551,393 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: B64C 2027/002 mounted between the rotor drive and the fuselage
• CPC Class Codes: B64C 27/001 Vibration damping devices
• CPC Class Codes: F16F 7/1034 of movement of a liquid

Abstract

A rotorcraft vibration isolation system includes a plurality of liquid inertia vibration elimination (LIVE) units mounted on a first rotorcraft surface, an accumulator mounted on a second rotorcraft surface at a location that is remote from locations of the plurality of LIVE units, and a fluid passage to connect the accumulator to the plurality of LIVE units in parallel. The fluid passage has sufficient length to traverse between the location of the accumulator and each location of each LIVE unit. During rotorcraft operation, the second rotorcraft surface experiences lesser periodic vibration than the first rotorcraft surface.

Claims

1. A rotorcraft vibration isolation system comprising:

a plurality of liquid inertia vibration elimination (LIVE) units mounted on a first rotorcraft surface;

an accumulator mounted on a second rotorcraft surface at a location that is remote from locations of the plurality of LIVE units, wherein, during rotorcraft operation, the second rotorcraft surface experiences lesser periodic vibration than the first rotorcraft surface; and

a fluid passage to connect the accumulator to the plurality of LIVE units in parallel, the fluid passage having sufficient length to traverse between the location of the accumulator and each location of each LIVE unit.

2. The system of claim 1, wherein the accumulator is configured to provide positive pressure to the plurality of LIVE units throughout a range of rotorcraft operating temperatures.

3. The system of claim 1, wherein the fluid passage includes a plurality of tubing sections, each tubing section connecting the accumulator and a respective LIVE unit and wherein the fluid passage includes either flexible or hard tubing.

4. The system of claim 1, wherein each tubing section includes a respective valve.

5. The system of claim 4, wherein the valve is a pressure sensitive valve or a unidirectional valve, and wherein the valve is positioned nearer to the LIVE unit than the accumulator in the tubing section.

6. The system of claim 1, wherein a distance between the location of the accumulator and the locations of the plurality of LIVE units is at least six inches.

7. The system of claim 1, wherein the first rotorcraft surface includes a rotorcraft transmission and the second rotorcraft surface includes a rotorcraft fuselage.

8. The system of claim 1, wherein each LIVE unit includes tuned fluid mass to generate pressure oscillation, and wherein the accumulator is a passive accumulator configured to compensate the pressure oscillation in each LIVE unit.

9. A rotorcraft comprising:

a first rotorcraft surface;

a second rotorcraft surface which, during rotorcraft operation, experiences lesser periodic vibration than the first rotorcraft surface; and

a rotorcraft vibration isolation system comprising;

one or more liquid inertia vibration elimination (LIVE) units mounted on the first rotorcraft surface;

an accumulator mounted on the second rotorcraft surface at a location that is remote from locations of the one or more LIVE units; and

a fluid passage to connect the accumulator to the one or more LIVE units in parallel, the fluid passage having sufficient length to traverse between the location of the accumulator and each location of each LIVE unit.

10. The rotorcraft of claim 9, wherein the accumulator is configured to provide positive pressure to the one or more LIVE units throughout a range of rotorcraft operating temperatures.

11. The rotorcraft of claim 9, wherein the fluid passage includes either flexible or hard tubing.

12. The rotorcraft of claim 11, wherein the fluid passage includes a plurality of tubing sections, each tubing section connecting the accumulator and a respective LIVE unit and wherein the fluid passage includes either flexible or hard tubing.

13. The rotorcraft of claim 12, wherein each tubing section includes a valve positioned immediately adjacent the LIVE unit.

14. The rotorcraft of claim 9, wherein a distance between the location of the accumulator and the locations of the one or more LIVE units is at least six inches.

15. The rotorcraft of claim 9, wherein the first rotorcraft surface includes a rotorcraft transmission and the second rotorcraft surface includes a rotorcraft fuselage.

16. The rotorcraft of claim 9, wherein each LIVE unit includes tuned fluid mass to generate pressure oscillation, and wherein the accumulator is a passive accumulator configured to compensate the pressure oscillation in each LIVE unit.

17. A method for isolating periodic vibration in a system, the method comprising:

mounting a plurality of liquid inertia vibration elimination (LIVE) units on a first surface of a system;

mounting an accumulator on a second surface of the system at a location that is remote from locations of the plurality of LIVE units, wherein, during operation of the system, the second surface experiences lesser periodic vibration than the first surface; and

connecting the accumulator and the plurality of LIVE units in parallel using a fluid passage having sufficient length to traverse between the location of the accumulator and each location of each LIVE unit.

18. The method of claim 17, further comprising providing positive pressure to the plurality of LIVE units using the accumulator throughout a range of operating temperatures of the system.

19. The method of claim 17, wherein the system is a rotorcraft, and wherein the first surface includes a rotorcraft transmission and the second rotorcraft surface includes a rotorcraft fuselage.

20. The method of claim 17, wherein a distance between the location of the accumulator and the locations of the one or more LIVE units is at least six inches.