Claims
- 1. A vibration isolator comprising:
a housing defining a fluid chamber; a fluid disposed within the fluid chamber; a piston resiliently disposed within the housing; a means for resiliently coupling the piston to the housing; a tuning mass operably associated with the piston; and an active tuning element operably associated with the piston for selectively altering the dynamic characteristics of the vibration isolator.
- 2. The vibration isolator according to claim 1, wherein the piston serves as the tuning mass.
- 3. The vibration isolator according to claim 1, wherein the piston divides the fluid chamber into two volumes and a port passes through the piston such that the two volumes are in fluid communication.
- 4. The vibration isolator according to claim 3, wherein the port passes axially through the piston.
- 5. The vibration isolator according to claim 3, wherein the port is configured to eliminate large mean pressure shifts between the two volumes.
- 6. The vibration isolator according to claim 3, wherein the tuning mass is a rigid body slidingly disposed within the port.
- 7. The vibration isolation system according to claim 6, wherein the rigid body is a tungsten rod.
- 8. The vibration isolation system according to claim 6, wherein the tuning fluid is a silicone oil.
- 9. The vibration isolation system according to claim 3, wherein the tuning mass is a tuning fluid.
- 10. The vibration isolation system according to claim 9, wherein the tuning fluid is an organic fluid having non-corrosive properties, low viscosity, and high density.
- 11. The vibration isolator according to claim 1, wherein the housing is coupled to an isolated object.
- 12. The vibration isolator according to claim 1, wherein the piston is coupled to an isolated object.
- 13. The vibration isolator according to claim 1, wherein the active tuning element comprises:
an actuation piston for selectively actuating the fluid; an actuator coupled to the actuation piston; and a control system for controlling the actuation of the actuator.
- 14. The vibration isolator according to claim 13, wherein the actuator is a piezoceramic material.
- 15. The vibration isolator according to claim 13, wherein the actuator is a magnetostrictive material.
- 16. The vibration isolator according to claim 13, wherein the actuator is electromagnetic.
- 17. The vibration isolator according to claim 13, wherein the actuator is a pneumatic actuator.
- 18. The vibration isolator according to claim 13, wherein the actuator is a hydraulic actuator.
- 19. The vibration isolator according to claim 6, further comprising:
a plurality of bypass valves operably associated with the piston to prevent overtravel of the tuning mass during large changes in loads.
- 20. The vibration isolator according to claim 1, wherein the active tuning element comprises:
a first set of three active tuning elements operating in a generally axial direction upon a first concave plate member, such that the forces of the first set of three active tuning elements are balanced; and a second set of three active tuning elements operating in an opposing generally axial direction upon a second concave plate member, such that the forces of the second set of three active tuning elements are balanced; wherein the piston is configured with convex surfaces to matingly coupled with the first concave plate member and the second concave plate member, such that the balanced forces from the first and second sets of three active tuning elements are transferred to the piston.
- 21. The vibration isolator according to claim 1, further comprising:
a means for preventing non-axial movement of the active tuning element.
- 22. The vibration isolator according to claim 21, wherein the means for preventing non-axial movement of the active tuning element comprises:
a flexure disposed between the housing and the active tuning element.
- 23. The vibration isolator according to claim 21, wherein the means for preventing non-axial movement of the active tuning element comprises:
hemispherical end caps disposed on each end of the active tuning element; receivers coupled to the piston and the housing, the receivers being configured to matingly receive the hemispherical end caps; and an elastomeric material disposed between the hemispherical end caps and the receivers for absorbing moments generated by the active tuning element.
- 24. The vibration isolator according to claim 1, further comprising:
a first mode of operation wherein the vibration isolator further comprises:
a tubular shaft configured for installation into the port passing through the piston, the first tubular shaft defining a tuning port through which the fluid passes from one volume of the fluid chamber to the other; and a second mode of operation wherein the vibration isolator further comprises:
a tubular shaft configured for installation into the port passing through the piston, the second tubular shaft defining a tuning port through which the fluid passes from one volume of the fluid chamber to the other; and a rigid body tuning mass disposed within the tubular shaft; wherein the first mode of operation is interchangeable with the second mode of operation.
- 25. The vibration isolator according to claim 1, wherein the means for resiliently coupling the piston to the housing comprises:
an elastomer coupled to the piston and the housing.
- 26. The vibration isolator according to claim 1, wherein the means for resiliently coupling the piston to the housing is a frequency step change assembly comprising:
an annular outer member adapted for coupling to the housing; an annular inner member adapted for coupling to the piston; an intermediate member disposed between the outer member and the inner member; a first annular elastomeric member disposed between the outer member and the intermediate member, the first annular elastomeric member having a first radius; a second annular elastomeric member disposed between the inner member and the intermediate member, the second annular elastomeric member having a second radius; a switching mechanism for switching between:
a first frequency mode in which the outer member, the first elastomeric member, and the intermediate member are coupled together such that the effective piston radius is the first radius and the vibration isolator operates at a first isolation frequency; and a second frequency mode in which the inner member, the second elastomeric member, and the intermediate member are coupled together such that the effective piston radius is the second radius and the vibration isolator operates at a second isolation frequency.
- 27. The vibration isolator according to claim 26, wherein the first isolation frequency is about 16.6 Hertz, and the second isolation frequency is about 19.9 Hertz.
- 28. A vibration isolation system comprising:
an aircraft comprising:
a fuselage; a wing member; a propulsion system carried by the aircraft; and a vibration isolator disposed between the fuselage and the wing member, the vibration isolator comprising:
a housing defining a fluid chamber; a tuning mass disposed within the fluid chamber; a piston resiliently disposed within the housing, the piston dividing the fluid chamber into two volumes; a means for resiliently coupling the piston to the housing; a port passing through the piston such that the two volumes are in fluid communication; and an active tuning element operably associated with at least one of the volumes for selectively altering the dynamic characteristics of the vibration isolator; whereby oscillatory forces generated by the propulsion system are isolated.
- 29. The vibration isolation system according to claim 28, wherein the tuning mass is a rigid body slidingly disposed within the port.
- 30. The vibration isolation system according to claim 29, wherein the rigid body is a tungsten rod.
- 31. The vibration isolation system according to claim 28, wherein the tuning mass is a tuning fluid.
- 32. The vibration isolation system according to claim 31, wherein the tuning fluid is an organic fluid having non-corrosive properties, low viscosity, and high density.
- 33. The vibration isolation system according to claim 28, wherein the aircraft is a helicopter.
- 34. The vibration isolation system according to claim 28, wherein the aircraft is a tilt rotor aircraft.
- 35. The vibration isolation system according to claim 28, wherein the aircraft is a quad tilt rotor aircraft.
- 36. The vibration isolation system according to claim 28, wherein the active tuning element is operably located between the wing member and the tuning mass.
- 37. The vibration isolation system according to claim 28, wherein the active tuning element is operably located between the fuselage and the tuning mass.
Parent Case Info
[0001] This application claims the benefit of U.S. Provisional Application No. 60/235,656, filed Sep. 26, 2000, titled “Method and Apparatus for Improved Vibration Isolation.”
Provisional Applications (1)
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Number |
Date |
Country |
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60235656 |
Sep 2000 |
US |