US3887296A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Vibration absorbing systems
Assignee: Westland Group PLC
•
Filing: 1973-10-23
•
Granted: 1975-06-03
•
Expires: 1993-10-23
Abstract
Abstract A vibration system for a rotary wing aircraft includes at least three vibration absorbers mounted symmetrically about the vertical axis of rotation of the rotors for rotation in a plane generally perpendicular to that axis. Each absorber includes a housing having an aperture formed therein which extends generally parallel to the axis of rotation. The aperture is defined in part by an outboard hollowed surface which faces the axis of rotation, a spherical ball being retained by centrifugal force in contact with that surface. The hollowed surface has a first radius in a first plane perpendicular to the plane of rotation so that forces of a specific frequency in that plane are cancelled or reduced and a second radius in a second plane parallel to the plane of rotation so that forces of a different frequency in the second plane are cancelled or reduced.
Inventors
- 👤 Noel Mills
- 👤 David Ernest Hall Balmford
- 👤 James Edwin Saunders
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 02:18
CPC Classifications
F; F16; F16F; F16F15/00; F16F15/10; F16F15/14; B; B64; B64C; B64C27/00; B64C27/001; Y; Y10; Y10S; Y10S416/00; Y10S416/50
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
208 words
In a rotary wing aircraft having a main rotor system including a rotor hub and a plurality of rotor blades extending radially therefrom, a vibration absorbing system including at least three vibration absorbers mounted symmetrically about a generally vertical axis of rotation of the rotor system for rotation in a plane generally perpendicular to the rotational axis, each vibration absorber including a housing having an aperture formed therein which extends in a direction generally parallel with the axis of rotation, the aperture being defined in part by an outboard hollowed surface disposed with the concave portion thereof facing the axis of rotation, a spherical ball retained in the aperture so that during rotation of the rotor system the ball is retained in contact with the hollowed surface by centrifugal force, said hollowed surface having a first radius in a first plane generally perpendicular to the plane of rotation so that during operation the absorber cancels or reduces a vibration force of a particular frequency in said first plane, and a second and different radius in a second plane generally coincident or parallel with the plane of rotation so that during operation the absorber simultaneously cancels or reduces a vibration force of a different frequency in said second plane.
Claim 2
Dependent Claim
208 words
In a rotary wing aircraft having a main rotor system including a rotor hub and a plurality of rotor blades extending radially therefrom, a vibration absorbing system including at least three vibration absorbers mounted symmetrically about a generally vertical axis of rotation of the rotor system for rotation in a plane generally perpendicular to the rotational axis, each vibration absorber including a housing having an aperture formed therein which extends in a direction generally parallel with the axis of rotation, the aperture being defined in part by an outboard hollowed surface disposed with the concave portion thereof facing the axis of rotation, a spherical ball retained in the aperture so that during rotation of the rotor system the ball is retained in contact with the hollowed surface by centrifugal force, said hollowed surface having a first radius in a first plane generally perpendicular to the plane of rotation so that during operation the absorber cancels or reduces a vibration force of a particular frequency in said first plane, and a second and different radius in a second plane generally coincident or parallel with the plane of rotation so that during operation the absorber simultaneously cancels or reduces a vibration force of a different frequency in said second plane.
Claim 3
Dependent Claim
208 words
In a rotary wing aircraft having a main rotor system including a rotor hub and a plurality of rotor blades extending radially therefrom, a vibration absorbing system including at least three vibration absorbers mounted symmetrically about a generally vertical axis of rotation of the rotor system for rotation in a plane generally perpendicular to the rotational axis, each vibration absorber including a housing having an aperture formed therein which extends in a direction generally parallel with the axis of rotation, the aperture being defined in part by an outboard hollowed surface disposed with the concave portion thereof facing the axis of rotation, a spherical ball retained in the aperture so that during rotation of the rotor system the ball is retained in contact with the hollowed surface by centrifugal force, said hollowed surface having a first radius in a first plane generally perpendicular to the plane of rotation so that during operation the absorber cancels or reduces a vibration force of a particular frequency in said first plane, and a second and different radius in a second plane generally coincident or parallel with the plane of rotation so that during operation the absorber simultaneously cancels or reduces a vibration force of a different frequency in said second plane.
Claim 4
Dependent Claim
208 words
In a rotary wing aircraft having a main rotor system including a rotor hub and a plurality of rotor blades extending radially therefrom, a vibration absorbing system including at least three vibration absorbers mounted symmetrically about a generally vertical axis of rotation of the rotor system for rotation in a plane generally perpendicular to the rotational axis, each vibration absorber including a housing having an aperture formed therein which extends in a direction generally parallel with the axis of rotation, the aperture being defined in part by an outboard hollowed surface disposed with the concave portion thereof facing the axis of rotation, a spherical ball retained in the aperture so that during rotation of the rotor system the ball is retained in contact with the hollowed surface by centrifugal force, said hollowed surface having a first radius in a first plane generally perpendicular to the plane of rotation so that during operation the absorber cancels or reduces a vibration force of a particular frequency in said first plane, and a second and different radius in a second plane generally coincident or parallel with the plane of rotation so that during operation the absorber simultaneously cancels or reduces a vibration force of a different frequency in said second plane.
Claim 5
Dependent Claim
20 words
A system as claimed in claim 1, wherein each absorber is located at the end of a radially extending arm.
Claim 6
Dependent Claim
44 words
A system as claimed in claim 2, wherein opposed inner and outer flanged portions are provided on the housing of each absorber, the inner flanges being connected to the ends of the arm and the outer flanges providing attachment for a main rotor blade.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-02 | 1978-12-02 | 1979-06-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-02 | 1982-12-02 | 1983-06-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-02 | 1986-12-02 | 1987-06-03 | $7700.00 | Window Closed / Lapsed |