US3922955A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Fail-fixed servovalve
Assignee: General Electric Co
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Filing: 1974-01-29
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Granted: 1975-12-02
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Expires: 1994-01-29
Abstract
Abstract A fail-fixed servovalve includes a jet pipe for discharging a pressurized liquid wherein the jet pipe may be selectively signaled to deflect and unbalance the pressures at opposing ends of a spool which would otherwise remain centered within a sleeve by resilient means at opposing ends thereof. The spool includes a plurality of circumferentially relieved areas interspaced between a plurality of lands with interconnecting passages therebetween wherein a servopiston may be actuated to move by pressurized liquid selectively received from the sleeve and spool such that a sudden loss of either the deflecting signal or the pressurized liquid would operate to block the flow of liquid to the servopiston, locking it in place.
Inventors
- 👤 Howard Berdolt Kast
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 17:28
CPC Classifications
F; F15; F15B; F15B11/00; F15B11/08; F15B11/12; F15B11/127; F15B11/128; F15B13/00; F15B13/02; F15B13/04; F15B13/042; F15B13/043; F15B13/0436; Y; Y10; Y10T; Y10T137/00; Y10T137/8593; Y10T137/86493; Y10T137/86574; Y10T137/86582; Y10T137/8659; Y10T137/86598; Y10T137/8667; Y10T137/86694; Y10T137/86702
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
325 words
A servovalve comprising: a jet pipe for discharging a jet of pressurized liquid; deflecting means responsive to an input signal for deflecting the jet pipe in a direction determined by the input signal; a sleeve having a plurality of ports therethrough one of which receives an inlet flow of pressurized liquid; a spool translatably disposed within the sleeve and centered therein by resilient means at opposing ends thereof wherein the spool includes a plurality of circumferentially relieved areas interspaced between a plurality of cirCumferential lands and wherein selected relieved areas may be placed in flow communication with selected ports in the sleeve by translation of the spool; a pair of receiver passages in flow communication with opposite ends of the sleeve and disposed to accept an equal amount of liquid from the jet pipe when the jet pipe is in the nondeflected position and an unequal amount of liquid when the jet pipe is in the deflected position whereby an input signal to the deflecting means operates to deflect the jet pipe causing the receiver passages to receive unequal amounts of liquid and thereby unbalance the pressure at opposing ends of the spool to cause the spool to translate in the direction of lower pressure; a servopiston having a piston translatably disposed within a bore each side of which communicates with separate ports in the sleeve; passage means internal to the spool and interconnecting selected relieved areas for delivering a pulse of pressurized liquid to a first side of the piston and porting away pressurized liquid from the opposite side of the piston when the spool is translated in one direction and delivering a pulse of pressurized liquid to the opposite side of the piston and porting away pressurized liquid from the first side of the piston when the spool is translated in the opposite direction such that there is no fluid flow to the servopiston when the spool is fully translated in either direction.
Claim 2
Dependent Claim
325 words
A servovalve comprising: a jet pipe for discharging a jet of pressurized liquid; deflecting means responsive to an input signal for deflecting the jet pipe in a direction determined by the input signal; a sleeve having a plurality of ports therethrough one of which receives an inlet flow of pressurized liquid; a spool translatably disposed within the sleeve and centered therein by resilient means at opposing ends thereof wherein the spool includes a plurality of circumferentially relieved areas interspaced between a plurality of cirCumferential lands and wherein selected relieved areas may be placed in flow communication with selected ports in the sleeve by translation of the spool; a pair of receiver passages in flow communication with opposite ends of the sleeve and disposed to accept an equal amount of liquid from the jet pipe when the jet pipe is in the nondeflected position and an unequal amount of liquid when the jet pipe is in the deflected position whereby an input signal to the deflecting means operates to deflect the jet pipe causing the receiver passages to receive unequal amounts of liquid and thereby unbalance the pressure at opposing ends of the spool to cause the spool to translate in the direction of lower pressure; a servopiston having a piston translatably disposed within a bore each side of which communicates with separate ports in the sleeve; passage means internal to the spool and interconnecting selected relieved areas for delivering a pulse of pressurized liquid to a first side of the piston and porting away pressurized liquid from the opposite side of the piston when the spool is translated in one direction and delivering a pulse of pressurized liquid to the opposite side of the piston and porting away pressurized liquid from the first side of the piston when the spool is translated in the opposite direction such that there is no fluid flow to the servopiston when the spool is fully translated in either direction.
Claim 3
Dependent Claim
169 words
The servovalve of claim 1 wherein the spool includes: a first centrally relieved area for receiving the inlet flow of pressurized liquid, second and third relieved areas each of which is adjacent on opposing end of the centrally relieved area and spaced apart therefrom by first and second respective lands wherein the second and third relieved areas are in flow communication with the centrally relieved area by a first internal spool passageway, fourth and fifth relieved areas adjacent the second relieved area and spaced apart therefrom by a third land with a fourth land interspaced between the fourth and fifth relieved areas wherein flow communication is established between the fourth and fifth relieved areas by a second internal spool passageway, and sixth and seventh relieved areas adjacent the third relieved area and spaced apart therefrom by a fifth land with a sixth land interspaced between the sixth and seventh relieved areas wherein flow communication is established between the sixth and seventh relieved areas by a third internal spool passageway.
Claim 4
Dependent Claim
280 words
The servovalve of claim 2 wherein the sleeve includes: a first port in flow communication with the space between the centrally relieved area and the sleeve for receiving the inlet flow of pressurized liquid; a second port spaced axially apart from the first port and in flow communication with one side of the servopiston wherein translation of the spool toward one end of the sleeve and back again operates to establish momentary flow communication between the second port and the space between the second relieved area and sleeve while translation of the spool in the opposing direction toward the other end of the sleeve and back again operates to establish momentary flow communication between the second port and the space between the fourth relieved area and sleeve; a third port spaced axially apart from the first and second ports in flow communication with the other side of the servopiston wherein translation of the spool toward one end of the sleeve and back again operates to establish momentary flow communication between the third port and the space between the third relieved area and sleeve while translation of the spool in the opposing direction toward the other end of the sleeve and back again operates to establish momentary flow communication between the third port and the space between the sixth relieved area and sleeve; a fourth outlet port spaced axially apart from the first, second, and third ports and in flow communication with the space between the fifth reLieved area and sleeve, and a fifth outlet port spaced axially apart from the first, second, third and fourth ports and in flow communication with the space between the seventh relieved area and sleeve.
Claim 5
Dependent Claim
51 words
The servovalve of claim 3 wherein the resilient means are springs disposed at opposing ends of the spool and the deflecting means is a torque motor having an armature secured to the jet pipe so as to exert a bending moment thereon when differential current is applied to the torque motor.
Claim 6
Dependent Claim
119 words
The servovalve of claim 1 wherein the input signal to the deflecting means is switched at a frequency exceeding the frequency response time of the servovalve such that the spool assumes a position within the sleeve offset from the central position, but not abutting either end of the sleeve wherein a continuous flow of liquid is conducted to one side of the servopiston while a continuous flow of liquid is ported away from the other side of the servopiston so as to impart a continuous movement to the servopiston, the velocity of the servopiston being an analog representation of the magnitude of the input signal applied to the deflecting means multiplied by the actual time the signal is applied.
Claim 7
Dependent Claim
146 words
The servovalve of claim 1 wherein the return to zero of the input signal to the deflecting means causes the jet pipe to return to the central position so that the receiver passages again receive equal amounts of liquid and balance the pressure at opposing ends of the spool such that the spool is returned by the resilient means to the center position within the sleeve during which time a second pulse of pressurized liquid is ported to the same side of the piston previously pulsed which side is once again brought into momentary flow communication with the pressurized liquid entering the sleeve by an internal spool passageway while at the same time a pulse of high pressure liquid is again ported away from the opposing side of the piston by another internal spool passageway thus moving the piston a second discreet distance within the bore.
Claim 8
Dependent Claim
71 words
The servovalve of claim 2 wherein the servopiston remains fail-fixed in the event that the signal to the deflecting means remains at its full deflected position causing the spool to remain at an end position within the sleeve; said servopiston remaining locked in position due to the alignment of the spool lands which block the flow of liquid to and from the servopiston where the spool is in the end 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) | 1978-12-01 | 1979-06-02 | 1979-12-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-01 | 1983-06-02 | 1983-12-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-01 | 1987-06-02 | 1987-12-02 | $7700.00 | Window Closed / Lapsed |