US3598207A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dual mode shock strut
Assignee: Pneumo Dynamics Corp
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Filing: 1969-01-28
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Granted: 1971-08-10
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Expires: 1989-01-28
Abstract
Abstract Increase in static internal pressure in the strut after landing of the aircraft opens a bypass valve paralleling the standard flow area to provide a softer vertical load response for taxiing.
Inventors
- 👤 Erwin Horst Hartel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 05:45
CPC Classifications
F; F16; F16F; F16F9/00; F16F9/32; F16F9/50; F16F9/512; F16F9/5123
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
187 words
A dual mode shock strut for an aircraft having a relatively hard vertical load response for landing and a relatively soft vertical load response for taxiing, comprising outer and inner telescoping casings defining a pair of chambers containing pressurized air and hydraulic fluid, one of said casings including an orifice plate the orifice of which provides a primary path of communication between the chambers through which fluid is displaced in compression of the strut, the other of said casings carrying a metering pin which moves relatively through the orifice to control the flow area as the strut compresses under landing shock to provide said relatively hard vertical load response, means forming a secondary path of fluid communication between the chambers in parallel to said orifice, and bypass valve means for normally closing said secondary path and opening the same responsive to attainment in both said chambers of the higher internal pressure which exists in the compressed strut in its ground support of the aircraft, thereby to increase the effective area for flow of fluid between the chambers and provide the relatively soft vertical load response for taxiing.
Claim 2
Dependent Claim
187 words
A dual mode shock strut for an aircraft having a relatively hard vertical load response for landing and a relatively soft vertical load response for taxiing, comprising outer and inner telescoping casings defining a pair of chambers containing pressurized air and hydraulic fluid, one of said casings including an orifice plate the orifice of which provides a primary path of communication between the chambers through which fluid is displaced in compression of the strut, the other of said casings carrying a metering pin which moves relatively through the orifice to control the flow area as the strut compresses under landing shock to provide said relatively hard vertical load response, means forming a secondary path of fluid communication between the chambers in parallel to said orifice, and bypass valve means for normally closing said secondary path and opening the same responsive to attainment in both said chambers of the higher internal pressure which exists in the compressed strut in its ground support of the aircraft, thereby to increase the effective area for flow of fluid between the chambers and provide the relatively soft vertical load response for taxiing.
Claim 3
Dependent Claim
41 words
A shock strut as set forth in claim 1, wherein the bypass valve means includes means for exerting a closing force on the same in response to a differential of the internal pressure in said chambers during landing of the aircraft.
Claim 4
Dependent Claim
78 words
A shock strut as set forth in claim 2 wherein said metering pin is tubular and includes bypass ports forming said secondary path of fluid communication, said bypass valve means comprising a valve plunger having a plunger head slidable in said metering pin for blocking and unblocking said bypass ports, said plunger head having opposing sides respectively in communication with said chambers for developing a net force on said plunger head dependent upon relative pressures in said chambers.
Claim 5
Dependent Claim
50 words
A shock strut as set forth in claim 3 wherein said bypass valve means further includes a spring biasing said plunger head to the blocking position, and said sides of said plunger head are of different areas for developing a net force when the pressure in said chambers is equalized.
Claim 6
Dependent Claim
131 words
A dual mode shock absorber having different vertical load responses for landing and taxiing conditions of an aircraft, comprising inner and outer telescoping casings partly defining first and second chambers for hydraulic fluid, said inner casing including an orifice in communication with said chambers, said outer casing supporting a metering pin for movement through said orifice to control fluid flow therethrough, means forming a second path for fluid flow between said chambers, a valve operative to open and close said second path, first means urging said valve to a normally closed position, second means urging said valve to an open position, and third means urging said valve to the closed position, said second and third means providing variable forces dependent upon the relative pressure in said first and second chambers, respectively.
Claim 7
Dependent Claim
131 words
A dual mode shock absorber having different vertical load responses for landing and taxiing conditions of an aircraft, comprising inner and outer telescoping casings partly defining first and second chambers for hydraulic fluid, said inner casing including an orifice in communication with said chambers, said outer casing supporting a metering pin for movement through said orifice to control fluid flow therethrough, means forming a second path for fluid flow between said chambers, a valve operative to open and close said second path, first means urging said valve to a normally closed position, second means urging said valve to an open position, and third means urging said valve to the closed position, said second and third means providing variable forces dependent upon the relative pressure in said first and second chambers, respectively.
Claim 8
Dependent Claim
47 words
A shock absorber as set forth in claim 5 wherein said second and third means are responsive to fluid pressure in said first and second chambers respectively to develop a net force urging said valve to the open position when the pressures in said chambers are equal.
Claim 9
Dependent Claim
53 words
A shock absorber as set forth in claim 6 wherein said third means is operative to maintain said valve in the closed position during the landing condition of the aircraft when said casings are initially relatively telescoped and the pressure in said second chamber is higher than the pressure in said first chamber.
Claim 10
Dependent Claim
50 words
A shock absorber as set forth in claim 7 wherein said second and third means comprise a differential plunger head slidably mounted in said metering pin in operative relation to said second path forming means and said first means comprises a spring biasing said plunger head to the closed position.
Claim 11
Dependent Claim
70 words
A shock absorber as set forth in claim 8 wherein said metering pin comprises a closed end and an open end, the latter in communication with said second chamber, said second path forming means comprising bypass ports near said closed end, and further including a passage adjacent said closed end in communication with said first chamber for exposing one side of said plunger head to fluid in said first chamber.
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) | 1974-08-09 | 1975-02-08 | 1975-08-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-08-09 | 1979-02-08 | 1979-08-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-08-09 | 1983-02-08 | 1983-08-10 | $7700.00 | Window Closed / Lapsed |