Vibration dampening for horizontal stabilizers

Patent metadata

Field	Value
Publication number	US-9828084-B2
Application number	US-201514705863-A
Country	US
Kind code	B2
Filing date	May 6, 2015
Priority date	May 6, 2015
Publication date	Nov 28, 2017
Grant date	Nov 28, 2017

Abstract

Systems and methods provide for the mitigation of vibrational forces acting on a horizontal stabilizer of an aircraft. According to one aspect, a damper is coupled to a front portion of a horizontal stabilizer to dampen vibrations in a first degree of freedom, with another damper coupled to a mounting point of the horizontal stabilizer to dampen vibrations in a second degree of freedom. The dampers may be passive, operating independently to mitigate vibrational forces, or active, applying a mitigating force to the horizontal stabilizer based on real-time or estimated vibration states.

First claim

What is claimed is:

1. A vibration dampening system for a horizontal stabilizer of an aircraft, the system comprising:
a first damper coupled to a front portion of the horizontal stabilizer at a first location, the first damper configured to dampen a vibrational force in a first degree of freedom; and
a second damper coupled to the horizontal stabilizer proximate to a mounting point of the horizontal stabilizer at a second location different than the first location, the second damper configured to dampen the vibrational force in a second degree of freedom;
wherein each of the first damper and the second damper is independently mechanically coupled to the horizontal stabilizer.

2. The vibration dampening system of claim 1 , wherein the mounting point comprises a pivot point.

3. The vibration dampening system of claim 2 , wherein the pivot point comprises a first pivot point around a pitch axis of the horizontal stabilizer, and wherein the vibration dampening system further comprises a third damper coupled to the horizontal stabilizer proximate to a second pivot point around the pitch axis of the horizontal stabilizer, the third damper configured to dampen the vibrational force in the second degree of freedom.

4. The vibration dampening system of claim 2 , wherein at least one of the first damper and the second damper comprises a passive damper.

5. The vibration dampening system of claim 4 , wherein the passive damper comprises a visco-elastic damper.

6. The vibration dampening system of claim 5 , wherein the visco-elastic damper comprises two springs, a first spring configured to mitigate vibrations according to a first frequency, and a second spring configured to mitigate vibrations according to a second frequency.

7. The vibration dampening system of claim 6 , wherein one of the first and second frequencies is selected based on a frequency of a disturbance in an exit airflow from a ducted fan engine.

8. The vibration dampening system of claim 6 , wherein the two springs are concentrically arranged within the visco-elastic damper.

9. The vibration dampening system of claim 8 , wherein the first spring abuts a fixed bottom damper wall at a first end and a moveable top damper wall at a second end, the moveable top damper wall connected to a damper piston within a viscous fluid chamber such that linear translation of the damper piston is resisted upon by viscous fluid within the viscous fluid chamber while compressing the first spring, and
wherein the second spring is positioned within the first spring and abuts a top surface of the viscous fluid chamber at a first inner spring end and the moveable top damper wall at a second inner spring end.

10. The vibration dampening system of claim 6 , wherein the two springs are separated from one another.

11. The vibration dampening system of claim 2 , wherein the first degree of freedom comprises a fore-aft direction substantially parallel to a longitudinal axis of the aircraft and wherein the second degree of freedom comprises an up-down direction substantially normal to the longitudinal axis of the aircraft.

12. The vibration dampening system of claim 2 , wherein the first degree of freedom comprises a fore-aft direction substantially parallel to a longitudinal axis of the aircraft and wherein the second degree of freedom comprises an angular direction with respect to the longitudinal axis of the aircraft.

13. The vibration dampening system of claim 2 , further comprising a bank of parallel dampers coupled to the horizontal stabilizer proximate to the pivot point of the horizontal stabilizer, wherein the bank of parallel dampers comprises the second damper and a third damper, the second damper configured to dampen the vibrational force in the second degree of freedom within a first frequency and the third damper configured to dampen the vibrational force in the second degree of freedom within a second frequency.

14. The vibration dampening system of claim 2 , wherein at least one of the first damper and the second damper comprises an active damper.

15. The vibration dampening system of claim 14 , wherein the active damper comprises an electric linear actuator, and wherein the vibration dampening system further comprises:
a vibration dampening computer operative to determine an actuator command to mitigate a vibration frequency associated with the horizontal stabilizer, and to provide the actuator command to the electric linear actuator for execution by the electric linear actuator.

16. The vibration dampening system of claim 15 , the system further comprising:
a plurality of accelerometers or position sensors configured to measure a real-time vibration state associated with the horizontal stabilizer and to provide the real-time vibration state to the vibration dampening computer,
wherein determining the actuator command to mitigate the vibration frequency comprises determining the actuator command to mitigate the real-time vibration state measured by the plurality of accelerometers or position sensors.

17. The vibration dampening system of claim 15 , wherein determining the actuator command to mitigate the vibration frequency comprises:
receiving one or more aircraft parameters corresponding to a current state of the aircraft or an aircraft system;
determining an estimated vibration state associated with the horizontal stabilizer based on the one or more aircraft parameters; and
determining the actuator command to mitigate the estimated vibration state.

18. The vibration dampening system of claim 17 , wherein the one or more aircraft parameters comprise:
one or more of an engine setting, a flight characteristic, an aircraft characteristic, a flight control setting, and an ambient parameter.

19. The vibration dampening system of claim 15 , the system further comprising:
a plurality of accelerometers or position sensors configured to measure a real-time vibration state associated with the horizontal stabilizers and to provide the real-time vibration state to the vibration dampening computer,
wherein determining the actuator command to mitigate the vibration frequency comprises:
receiving one or more aircraft parameters corresponding to a current state of the aircraft or an aircraft system;
determining an estimated vibration state associated with the horizontal stabilizer based on the one or more aircraft parameters;
determining the actuator command to mitigate the estimated vibration state;
providing instructions from the vibration dampening computer to the electric linear actuator to move the horizontal stabilizer according to the actuator command determined to mitigate the estimated vibration state;
receiving the real-time vibration state measured by the plurality of accelerometers or position sensors;
determining a corrective actuator command based on the real-time vibration state; and
providing the corrective actuator command to the electric linear actuator.

20. The vibration dampening system of claim 14 , wherein the active damper comprises a visco-elastic damper having a variable coefficient dampening element, and wherein the vibration dampening system further comprises:
a vibration dampening computer operative to determine a pressure command for the variable coefficient dampening element to mitigate a vibration frequency associated with the horizontal stabilizer, and to actuate a variable flow valve in a fluid accumulator circuit according to the pressure command to manage a dampening coefficient within the variable coefficient dampening element to m

Assignees

• Boeing Co

Inventors

• Golshany Sina Sam
• Erickson Todd W
• Tretow Paul R
• Huntly David M

Classifications

• B64C1/26

  Attaching the wing or tail units or stabilising surfaces · CPC title

• F16F2228/066

  Variable stiffness · CPC title

• F16F2230/18

  Control arrangements · CPC title

• F16F15/002

  characterised by the control method or circuitry (control of mechanical oscillations per se G05D19/00) · CPC title

• B64C5/02 Primary

  Tailplanes · CPC title