Patent US3747913A successfully refreshed from Google Patents.
US3747913A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fluid spring shock absorbers
Assignee: Dowty Rotol Ltd
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Filing: 1971-08-02
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Granted: 1973-07-24
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Expires: 1991-08-02
Abstract
Abstract A shock absorbing and energy dissipating device suitable for an aircraft landing gear comprising: I. A CYLINDER; II. A PISTON ROD, OF SMALLER DIAMETER THAN THE INTERNAL DIAMETER OF THE CYLINDER, MOVABLE INTO AND OUT FROM THE CYLINDER THROUGH A SEAL AT ONE END OF THE CYLINDER, THE OTHER END OF THE CYLINDER, WHICH IS THE END INTENDED TO BE LOWERMOST IN USE, BEING CLOSED; III. A PISTON CARRIED BY THE PISTON ROD AND SEALINGLY ENGAGING THE CYLINDER; IV. A VOLUME OF LIQUID IN THE CYLINDER; V. MEANS FOR RESTRICTING FLOW OF LIQUID FROM ONE SIDE OF THE PISTON TO THE OTHER AS THE PISTON MOVES IN THE CYLINDER TOWARDS SAID OTHER END OF THE CYLINDER; VI. A CONTAINER, CONTAINING A VOLUME OF GAS IN DIRECT UNRESTRICTED COMMUNICATION WITH LIQUID AT THE SAID ONE END OF THE CYLINDER; AND VII. FLOW-PASSAGE MEANS ADAPTED TO PERMIT UNRESTRICTED FLOW OF FLUID FROM ONE SIDE OF THE PISTON TO THE OTHER WHEN THE DEVICE IS IN ITS FULLY-EXTENDED POSITION; VIII. THE LIQUID AND THE GAS BEING PRESSURIZED IN THE FULLY EXTENDED POSITION OF THE DEVICE TO A VALUE ADAPTED TO OVERCOME FRICTIONAL FORCE ASSOCIATED WITH THE DEVICE WHEN AN EXTERNAL LOAD THEREON IS REMOVED THEREBY TO EXTEND THE DEVICE TO ITS FULLY-EXTENDED POSITION; AND IX. THE VOLUME OCCUPIED BY GAS IN SUCH POSITION BEING LESS THAN THE VOLUME OF THE PISTON ROD INTRODUCED INTO THE CYLINDER BY MOVEMENT OF THE ROD FROM THE FULLY-EXTENDED POSITION TO THE FULLY-CONTRACTED POSITION.
Inventors
- 👤 R Savery
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 18:48
CPC Classifications
F; F16; F16F; F16F9/00; F16F9/06; F16F9/063; B; B64; B64C; B64C25/00; B64C25/32; B64C25/58; B64C25/60
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
133 words
A shock absorbing and energy dissipating device suitable for an aircraft landing gear comprising: i. a main container having a single aperture intended to be uppermost in use ii. a plunger movable into and out of the aperture in the main container iii. a seal at the said aperture to sealingly engage against the relatively movable surface of the plunger iv. a volume of liquid within the main container v. a second container containing gas at pressure vi. a restricted flow passage between the main container and the second container for restricting liquid flow between them vii. an unrestricted flow passage for unrestricted gas flow in a generally upward direction from substantially the whole volume of the main container to the second container open when the plunger is in its fully extended position.
Claim 2
Dependent Claim
133 words
A shock absorbing and energy dissipating device suitable for an aircraft landing gear comprising: i. a main container having a single aperture intended to be uppermost in use ii. a plunger movable into and out of the aperture in the main container iii. a seal at the said aperture to sealingly engage against the relatively movable surface of the plunger iv. a volume of liquid within the main container v. a second container containing gas at pressure vi. a restricted flow passage between the main container and the second container for restricting liquid flow between them vii. an unrestricted flow passage for unrestricted gas flow in a generally upward direction from substantially the whole volume of the main container to the second container open when the plunger is in its fully extended position.
Claim 3
Dependent Claim
25 words
A shock absorbing and energy dissipating device as claimed in claim 1 wherein the piston rod is hollow and part thereof forms the second container.
Claim 4
Dependent Claim
74 words
A shock-absoring and energy dissipating device as claimed in claim 2 wherein the piston rod has abutment means adapted to determine the outermost position of the piston rod at which the piston is spaced from the said seal, the piston rod between the piston and the seal having axially-spaced holes each connecting the hollow piston rod to the cylinder at least the hole nearer to the seal forming part of said unrestricted flow passage.
Claim 5
Dependent Claim
27 words
A shock absorbing and energy dissipating device as claimed in claim 1 including valve means responsive to movement of the plunger to close the said unrestricted passage.
Claim 6
Dependent Claim
56 words
A shock absorbing and energy dissipating device as cliamed in claim 4 wherein the unrestricted flow passage includes at least one hole through the piston, and the valve means comprises a valve member adapted to seat over the end of the hole when the piston rod moves at more than a predetermined speed into the cylinder.
Claim 7
Dependent Claim
34 words
A shock absorbing and energy dissipating device as claimed in claim 5 wherein the valve member has at least one flow-restricting orifice co-operable with the hole through the piston when seated over the hole.
Claim 8
Dependent Claim
49 words
A shock absorbing and energy dissipating device as claimed in claim 5 wherein the hole through the piston is co-operable with a second valve member adapted to seat over the other end of said hole when the piston rod moves at more than a predetermined speed into the cylinder.
Claim 9
Dependent Claim
33 words
A shock absorbing and energy dissipating device as claimed in claim 7 wherein the second valve member has at least one flow-restricting orifice co-operable with the hole through the piston when seated thereover.
Claim 10
Dependent Claim
75 words
A shock absorbing and energy dissipating device as claimed in claim 1 wherein the main container is a cylinder and the plunger is a piston rod, a piston being formed at the inner end of the piston rod to slidably engage within the cylinder, the second container being in unrestricted connection with the zone defined between the piston, the piston rod, the cylinder and the seal, said zone forming part of the unrestricted flow passage.
Claim 11
Dependent Claim
22 words
A shock absorbing and energy dissipating device as claimed in claim 1 wherein the second container is formed internally within the plunger.
Claim 12
Dependent Claim
56 words
A shock absorbing and energy dissipating device as claimed in clain 1, the dimensions of the plunger being such taht the total reduction in fluid volume within the device when the plunger fully enters the main container is greater thAn the volume of gas in the second container in the fully extended position of the plunger.
Claim 13
Dependent Claim
58 words
A shock absorbing and energy dissipating device as claimed in claim 1 wherein the total fluid volume in the fully-extended position of the device does not exceed five times the reduction of total fluid volume caused by entry of the piston rod into the cylinder during movement of the rod from the fully-extended position to the fully-contracted position.
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) | 1976-07-23 | 1977-01-22 | 1977-07-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-07-23 | 1981-01-22 | 1981-07-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-07-23 | 1985-01-22 | 1985-07-24 | $7700.00 | Window Closed / Lapsed |