US3888436A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Airplane landing gear shock absorber
Assignee: Boeing Co
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Filing: 1974-04-01
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Granted: 1975-06-10
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Expires: 1994-04-01
Abstract
Abstract An aircraft landing gear shock absorbing strut of the telescopic pneumatic/hydraulic type having a two stage pneumatic spring, with one stage only functioning during the absorption of landing impact, and both stages functioning during taxiing. The strut includes improved means for controlling its damping characteristics such that its motion during the initial landing impact and subsequent rebound is heavily damped, but motion during taxi is damped to a lesser degree providing a more comfortable ride while taxiing.
Inventors
- 👤 Francis Sealey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 05:52
CPC Classifications
B; B64; B64C; B64C25/00; B64C25/32; B64C25/58; B64C25/60
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
318 words
A shock absorbing strut comprising: an outer and an inner cylinder, each having a closed end and open end, the cylinders being telescopically engaged at their open ends; a first piston assembly fitting internally in said inner cylinder, closely fitting the interior wall of said inner cylinder, and supported by means of a tube member from the closed end of said outer cylinder; and a second piston assembly attached to the inner wall of said inner cylinder and closely fitting the exterior wall of said tube member; wherein said strut is internally divided into three annular volumes; the first annular volume being bounded by the inner walls of the inner and outer cylinders, the outer wall of the tube member, the closed end of the outer cylinder and the first piston; the second annular volume being bounded by the inner wall of the inner cylinder, the outer wall of the tube member, and the first and second pistons; and the third annular volume including as boundaries the inner wall of the inner cylinder, the outer wall of the tube member, the second piston and the closed end of the inner cylinder; a plurality of orifice means such that a Portion of hydraulic fluid is forced through said orifice means during a compressive motion of said strut, thus dissipating energy through viscous friction; means for storing a portion of said energy by compression of a first volume of gas, said gas tending to expand said strut; means for dissipating a portion of said stored energy through viscous friction during expansion of said strut; means for storing addition energy by compression of a second volume of gas having a pre-determined initial volume; and means for reducing the viscous frictional forces opposing compression and expansion of said strut which means begin to function when said second volume of gas is compressed to a volume smaller than its said predetermined initial volume.
Claim 2
Dependent Claim
318 words
A shock absorbing strut comprising: an outer and an inner cylinder, each having a closed end and open end, the cylinders being telescopically engaged at their open ends; a first piston assembly fitting internally in said inner cylinder, closely fitting the interior wall of said inner cylinder, and supported by means of a tube member from the closed end of said outer cylinder; and a second piston assembly attached to the inner wall of said inner cylinder and closely fitting the exterior wall of said tube member; wherein said strut is internally divided into three annular volumes; the first annular volume being bounded by the inner walls of the inner and outer cylinders, the outer wall of the tube member, the closed end of the outer cylinder and the first piston; the second annular volume being bounded by the inner wall of the inner cylinder, the outer wall of the tube member, and the first and second pistons; and the third annular volume including as boundaries the inner wall of the inner cylinder, the outer wall of the tube member, the second piston and the closed end of the inner cylinder; a plurality of orifice means such that a Portion of hydraulic fluid is forced through said orifice means during a compressive motion of said strut, thus dissipating energy through viscous friction; means for storing a portion of said energy by compression of a first volume of gas, said gas tending to expand said strut; means for dissipating a portion of said stored energy through viscous friction during expansion of said strut; means for storing addition energy by compression of a second volume of gas having a pre-determined initial volume; and means for reducing the viscous frictional forces opposing compression and expansion of said strut which means begin to function when said second volume of gas is compressed to a volume smaller than its said predetermined initial volume.
Claim 3
Dependent Claim
74 words
The shock absorbing strut of claim 1 wherein said plurality of orifice means comprises: a plurality of orifices in the walls of said tube member permitting communication between the volumes located inside and outside of said tube member; and an orifice and check valve assembly in said first piston permitting restricted flow of hydraulic fluid in the direction of the open end of said outer cylinder but preventing significant flow in the opposite direction.
Claim 4
Dependent Claim
65 words
The shock absorbing strut of claim 1 wherein said plurality of orifice means comprises an orifice at the end of said tube member opposite the closed end of said outer cylinder cooperating with a metering pin mounted to the closed end of said inner cylinder so as to form a restricted passage between said metering pin and said orifice through which hydraulic fluid may pass.
Claim 5
Dependent Claim
48 words
The shock absorbing strut of claim 1 wherein said means for storing a portion of said energy comprises a volume of gas contained with the said first annular volume, said volume of gas being compressible by a compression of said strut but resiliently opposing compression of said strut.
Claim 6
Dependent Claim
89 words
The shock absorbing strut of claim 1 wherein the said means for dissipating a portion of said stored energy during expansion of said strut comprises means for containing a hydraulic fluid; a plurality of orifice means and a check valve assembly which permits restricted flow of hydraulic fluid in one direction during an expansion of said strut but prevents flow in the opposite direction, such that upon an expansion of said strut a portion of said hydraulic fluid is forced through said orifice thus dissipating energy through viscous friction.
Claim 7
Dependent Claim
66 words
The shock absorbing strut of claim 1 wherein said means for dissipating energy during expansion of said strut comprises an orifice in said second piston providing communication between said second and third annular volumes and a check valve assembly permitting restricted flow of hydraulic fluid through said orifice from said second annular volume into said third annular volume but preventing significant flow in the opposite direction.
Claim 8
Dependent Claim
83 words
The shock absorbing strut of claim 1 wherein said means for storing additional energy comprises a closed cylindrical chamber containing a free-floating piston, hydraulic fluid and a volume of gas, and having a port means in one end providing communication between said cylindrical chamber and said third annular volume such that an increase in pressure of hydraulic fluid within said third annular volume is transmitted to a portion of one side of said free-floating piston urging it to compress said volume of gas.
Claim 9
Dependent Claim
142 words
The shock absorbing strut of claim 1 wherein said means for reducing viscous frictional forces comprises a fluid-filled hollow cylindrical projection extending into said cylindrical chamber from one end thereof, a boss centrally located on the face of said free-floating piston such that it can seal the open end of said cylindrical projection, a plurality of taxi ports providing communication between the volume within said cylindrical projection and said third annular volume, and a plurality of taxi bleed ports through the walls of said cylindrical projection such that when said boss is seated and the strut iS being compressed, the buildup of hydraulic force on said free-floating piston is delayed by the restrictive effect of said taxi bleed ports, but when the force is sufficient to unseat it, pressure and fluid may pass through the taxi ports directly into said cylindrical chamber.
References Cited (Backward Citations)
US2735674A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-06-09 | 1978-12-09 | 1979-06-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-06-09 | 1982-12-09 | 1983-06-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-06-09 | 1986-12-09 | 1987-06-10 | $7700.00 | Window Closed / Lapsed |