US3613504A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Jamproof and fail operational servo valve for aircraft flight control hydraulic systems
Assignee: Boeing Co
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Filing: 1970-01-19
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Granted: 1971-10-19
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Expires: 1990-01-19
Abstract
Abstract When the primary valve spool in an aircraft flight control servo valve jams or seizes, at any position within its stroke, the aircraft pilot is enabled not only to halt the resulting run away condition of the affected power ram in the flight control system but is also enabled quite readily to regain full operational control of the aircraft. This regaining of control is made possible through the manual operation of an intermediate auxiliary valve sleeve which will shift with the jammed primary valve spool and the coordinated operation of a primary valve shutoff means which completely nullifies the action of the jammed primary valve spool by closing a return passage for hydraulic fluid.
Inventors
- 👤 Hans G Krauss
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 04:38
CPC Classifications
B; B64; B64C; B64C13/00
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
305 words
A servo valve assembly for aircraft hydraulic flight controls comprising a valve casing having fluid inlet and return passage means and pressure and return ports communicating with said passage means, a secondary valve sleeve mounted for axial movement in said casing and also having pressure and return ports adapted to communicate with the ports of the casing, a primary valve spool mounted for longitudinal reciprocation in said secondary valve sleeve and having ports movable into covering and uncovering relationship with the pressure and return ports of the secondary sleeve and also having return passage means, a primary valve shutoff spool within said primary valve spool and operable to close the return passage means of the primary valve spool, a manual linkage operable by the pilot of the aircraft to shift the primary valve spool longitudinally in said secondary sleeve, linkage means connected with the secondary valve sleeve including a movable part engageable with said shutoff spool to shift the shutoff spool axially in the direction for covering the return passage means of the primary valve spool, resilient preloading means connected with the secondary sleeve and resisting movement of the secondary sleeve but yielding to allow such movement when the primary valve spool jams in the secondary sleeve and a sufficient force is applied to the secondary sleeve through the jammed primary spool and said manual linkage, a cylinder associated with the valve casing, a flight control actuator ram within said cylinder for reciprocation including a piston element dividing said cylinder into a pair of chambers, fluid passage means interconnecting said chambers with said casing inlet and return passage means, said actuator ram being connected to a fixed structural element of the aircraft, and an actuator link on said cylinder and movable therewith and adapted for connection with an aircraft flight control element having aerodynamic loading.
Claim 2
Dependent Claim
305 words
A servo valve assembly for aircraft hydraulic flight controls comprising a valve casing having fluid inlet and return passage means and pressure and return ports communicating with said passage means, a secondary valve sleeve mounted for axial movement in said casing and also having pressure and return ports adapted to communicate with the ports of the casing, a primary valve spool mounted for longitudinal reciprocation in said secondary valve sleeve and having ports movable into covering and uncovering relationship with the pressure and return ports of the secondary sleeve and also having return passage means, a primary valve shutoff spool within said primary valve spool and operable to close the return passage means of the primary valve spool, a manual linkage operable by the pilot of the aircraft to shift the primary valve spool longitudinally in said secondary sleeve, linkage means connected with the secondary valve sleeve including a movable part engageable with said shutoff spool to shift the shutoff spool axially in the direction for covering the return passage means of the primary valve spool, resilient preloading means connected with the secondary sleeve and resisting movement of the secondary sleeve but yielding to allow such movement when the primary valve spool jams in the secondary sleeve and a sufficient force is applied to the secondary sleeve through the jammed primary spool and said manual linkage, a cylinder associated with the valve casing, a flight control actuator ram within said cylinder for reciprocation including a piston element dividing said cylinder into a pair of chambers, fluid passage means interconnecting said chambers with said casing inlet and return passage means, said actuator ram being connected to a fixed structural element of the aircraft, and an actuator link on said cylinder and movable therewith and adapted for connection with an aircraft flight control element having aerodynamic loading.
Claim 3
Dependent Claim
47 words
The structure of claim 1, and automatically operable means to lock said primary valve shutoff spool in the position to close said return passage means of the primary valve spool after the shutoff spool have been shifted by the linkage means connected with the secondary valve sleeve.
Claim 4
Dependent Claim
39 words
The structure of claim 2, and a stationary valve sleeve within the valve casing in surrounding relationship to said secondary valve sleeve, said stationary sleeve having said pressure and return ports communicating with said inlet and return passage means.
Claim 5
Dependent Claim
158 words
A jamproof servo valve assembly for aircraft hydraulic flight controls comprising a valve casing having fluid inlet and return connections, a secondary valve sleeve mounted for reciprocation within said casing, resilient means resisting movement of the secondary valve sleeve, a primary valve spool having a bore and disposed within said secondary valve sleeve for reciprocation and being subject to jamming in said secondary sleeve, linkage means having a connection with said primary spool to shift the same axially within the secondary valve sleeve, a primary valve shutoff spool in the bore of said primary valve spool and being movable relative to the primary valve spool to close certain return flow passages in the primary valve spool, and means having a connection with the secondary valve sleeve and responding to movement of such sleeve when said primary spool is jammed therein to move said shutoff spool to a position closing said return flow passages of the primary valve spool.
Claim 6
Dependent Claim
158 words
A jamproof servo valve assembly for aircraft hydraulic flight controls comprising a valve casing having fluid inlet and return connections, a secondary valve sleeve mounted for reciprocation within said casing, resilient means resisting movement of the secondary valve sleeve, a primary valve spool having a bore and disposed within said secondary valve sleeve for reciprocation and being subject to jamming in said secondary sleeve, linkage means having a connection with said primary spool to shift the same axially within the secondary valve sleeve, a primary valve shutoff spool in the bore of said primary valve spool and being movable relative to the primary valve spool to close certain return flow passages in the primary valve spool, and means having a connection with the secondary valve sleeve and responding to movement of such sleeve when said primary spool is jammed therein to move said shutoff spool to a position closing said return flow passages of the primary valve spool.
Claim 7
Dependent Claim
39 words
The structure of claim 4, and means connected with said shutoff spool to lock the same relative to said primary valve spool following movement of the shutoff spool by said means having a connection with the secondary valve sleeve.
Claim 8
Dependent Claim
57 words
The structure of claim 4, and a flight control actuator including a cylinder and ram associated with said valve assembly, and fluid passage means interconnecting end portions of the actuator cylinder with passage means of the valve casing, whereby fluid may be selectively ported into one end of the cylinder and returned from the other end thereof.
Claim 9
Dependent Claim
177 words
The structure of claim 4, and said valve casing having fluid pressure and return port means adapted to communicate with said fluid inlet and return connections, said secondary valve sleeve having porting means thereon shiftable into active and inactive relationship with the fluid pressure and return port means of the casing and also having additional pressure and return port means adapted to register with the corresponding port means of the valve casing, spaced lands on the primary valve spool movable into covering and uncovering relation with the pressure and return port means of the secondary valve sleeve, said primary spool having its own fluid return passage means adapted to communicate with the pressure and return port means of the secondary valve sleeve, and said casing and secondary valve sleeve each having narrow ports which register prior to movement of the secondary sleeve in the casing in response to a movement of the primary valve spool jammed in the secondary sleeve, the narrow port of the casing being in direct communication with said inlet connection of the casing.
Claim 10
Dependent Claim
233 words
A jamproof servo valve assembly for controlling a power actuator in a hydraulic aircraft flight control system, said servo valve assembly comprising a casing having fluid inlet and return connections and fluid passages leading to and from chambers of an actuator cylinder, a secondary valve sleeve within the casing and being normally held stationary relative to the casing but adapted to move axially under a predetermined force applied thereto, a primary valve spool mounted for axial movement within the secondary valve sleeve and being operable to port fluid to and from said actuator cylinder chambers under normal servo valve operating conditions, said primary spool capable of jamming within the secondary valve sleeve in a valve neutral position therein or in any position off of neutral along the total stroke of the primary valve sleeve, movement of the jammed primary valve spool forcing the secondary valve sleeve to move and to take over the control function of the primary spool in porting fluid to and from said chambers, said primary valve spool having return fluid passage means leading to said return connection, and an element movable with respect to the primary valve spool to close the return fluid passage means of the primary valve spool responsive to movement of the secondary valve sleeve in one direction with the primary spool jammed therein, whereby the primary valve spool is then functionally isolated from the system.
Claim 11
Dependent Claim
233 words
A jamproof servo valve assembly for controlling a power actuator in a hydraulic aircraft flight control system, said servo valve assembly comprising a casing having fluid inlet and return connections and fluid passages leading to and from chambers of an actuator cylinder, a secondary valve sleeve within the casing and being normally held stationary relative to the casing but adapted to move axially under a predetermined force applied thereto, a primary valve spool mounted for axial movement within the secondary valve sleeve and being operable to port fluid to and from said actuator cylinder chambers under normal servo valve operating conditions, said primary spool capable of jamming within the secondary valve sleeve in a valve neutral position therein or in any position off of neutral along the total stroke of the primary valve sleeve, movement of the jammed primary valve spool forcing the secondary valve sleeve to move and to take over the control function of the primary spool in porting fluid to and from said chambers, said primary valve spool having return fluid passage means leading to said return connection, and an element movable with respect to the primary valve spool to close the return fluid passage means of the primary valve spool responsive to movement of the secondary valve sleeve in one direction with the primary spool jammed therein, whereby the primary valve spool is then functionally isolated from the system.
Claim 12
Dependent Claim
119 words
The structure of claim 8, and said element movable with respect to the primary valve spool comprises another spool within a bore of the primary valve spool, and a mechanical linkage to move thE last-named spool and having a connection with the secondary valve sleeve and allowing the secondary valve sleeve and primary valve spool to move for a certain distance within the casing without effecting movement of the spool within the bore of the primary spool, a part of said linkage engaging and causing movement of the last-named spool relative to the primary spool after further movement of the primary spool with the secondary sleeve to cause closing of the return fluid passage means of the primary spool.
Claim 13
Dependent Claim
32 words
The structure of claim 9, and yielding means to automatically lock said spool in the bore of the primary valve spool in its moved position responsive to the operation of said linkage.
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) | 1974-10-18 | 1975-04-19 | 1975-10-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-18 | 1979-04-19 | 1979-10-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-18 | 1983-04-19 | 1983-10-19 | $7700.00 | Window Closed / Lapsed |