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Publication numberUS2941193 A
Publication typeGrant
Publication dateJun 14, 1960
Filing dateJul 16, 1956
Priority dateJul 16, 1956
Publication numberUS 2941193 A, US 2941193A, US-A-2941193, US2941193 A, US2941193A
InventorsPatton Henry W
Original AssigneeCollins Radio Co
Export CitationBiBTeX, EndNote, RefMan
External Links: USPTO, USPTO Assignment, Espacenet
Autopilot monitor system
US 2941193 A
Abstract  available in
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Claims  available in
Description  (OCR text may contain errors)

June 14, 1960 H. w. PATTON 2,941,193

AuToPILoT MONITOR SYSTEM Filed July 1s, 195e 9 ,N E s a@ m q s Illu lEllhll-uwll l o 's 2 5l r si D q BIL E Q b *z i9 'n q III| u o &

f u) E g Ll INVENTOR.

S HENRY W PnTroN www@ A Tro RNsvs AUTOPILO'I MONTIOR SYSTEM Henry W. Patton, Cedar Rapids, Iowa, assignor to Collins Radio Company, Cedar Rapids, Iowa, a corporation of Iowa Y v Filed July 16, 1956, Ser. No. 597,955

This invention relates to alarm circuits, and more particularly to an electronic alarm circuit for adaptation with automatic pilot systems.

This current produces a directional torque with the greater' torque being applied to the capstan by the clutch with the greater current flowing through it. In an aircraft automatic pilot system a malfunction in the control unit or in the operation of these clutches can result in tragic consequences to the aircraft. This invention provides an alarm circuit which will indicatev malfunctioning in the circuit used to control the capstan, yet be'rclatively in sensitive to normal maneuvering.

This invention provides an alarm circuit which will be actuated vwhen the current flowing in'one of the two clutches is of a predetermined value for a specified time interval. This current may be in one direction only,l due to a large sustained signal, or it may result from a sustained differential signal, causing differences in the currents in the related clutches. These current differences cause the alarm system of this invention to operate. n

' This invention also provides for normal increase in the average current iiow through the clutches, which occurs when there is an increase in the roughness of the weather.

This invention also provides for large momentary command signals which will cause large currents to ow momentarily but will not necessarily of themselves operate the alarm circuit. The alarm circuit of this invention will operate only with a large and relatively prolonged command voltage or current being applied in a single direction.

It is a feature of this invention that the currents flowing through the clutch coils determine the functioning of the alarm circuit. It is a further feature of this invention that only true malfunctioning of the automatic pilot system will operate the alarm circuit, while full clutch currents of a transient nature will not actuate the alarm.

It is an object of this invention to provide an alarm circuit for use in an automatic pilot system which will be responsive to malfunctionings of the automatic pilot system. It is a further object of this invention to provide an alarm circuit where the currents in two clutches are compared and where only a predetermined differential effect for a predetermined length of time will operate the alarm circuit. It is a still further object of this invention to provide an alarm circuit which does not respond to the current flow in the clutch coils caused by strong or large command signals when these signals are of normal The control for United States Patent 2,941,193 Patented June 14, 1960 ICC duration. It is another object of this invention to-provide an economical alarm circuit for use with automatic pilot systems which may be combined to permit independent operation of any single axis alarm without interfering with the alarms and operations associated with the remaining axes.

These and other objects of this invention will becomel apparent when the following description is read in con-- junction with the drawings, in which Figure 1 is a schematic diagram of one embodiment of this invention;

Figure 2'is a schematic diagram of this invention 'as'. applied to aithree-axis control system; and

Figure 3 is a view of one embodiment of a clutch. mechanism and gearing used to control the rotation of.' the capstan.

Referring now to Figure 3, the continuously running motor 8 turns. the gears connected to the clutches 7. The currents flowing through the coils in the clutches 7 deter# mine the direction of rotation and the velocity of rota-- tion of the gear 9. Gear 9 then rotates capstan 10 in. conformity with the signals from the clutches 7. Rotation of the capstan 10 provides the final mechanical control signals which are delivered to the various airplane controls, such as the elevator, aileron, and rudder.

Figure l is a detailed schematic of one embodiment of' this invention. The control signals are generated and fed to amplifier 5 as input signals. These input signals are amplified in amplifier 5 and then applied to the coils 6. of the clutches 7. The signals fed to the clutch coils. will cause a current to fiow in one of the coils 6 throughA one half of the filament of tube 11 to ground. Tube 11" is depicted as a double diode which may be replaced by two individual diodes. If an excessively large amount of current flows through either of the clutch coils 6 for an extended period of time, one half of the filament of tube 11 will heat to the' emissive point and will cause conduction in this half of the tube. Whenever conduction occurs on either side of tube 11, a current ilows through the coil 4 of neutral center differential relay 12. This current will actually flow through one half of coil 4 of the relay 12 for each clutch action, i.e., right or left or uptor down. The current results from the application of the alternating current voltage from source 18 to the plate circuit of tube 11 which may include gas-filled tubes 16 and parallel connected resistors 17. When a differential or net magnetic pull is created by currents flowing in either side of relay 12, the contact arm will close the contacts 13 thereby initiating an alarm. The contacts and contact arm are designated by the numeral 13 in Figure l. The swinging of the contact arm will operate the alarm through the indicator 14 from the power source 15.

During normal fiight in smooth air the clutch currents ilowing through the filament halves are approximately equal and are normally small. Consequently, there is little or no heating of the filament and little tube conduction occurs which would cause operation of the alarm circuitry. In rough air, false operation of the alarm circuit is prevented by the combination of the inverse thermal time delay action of the tube filaments and the differential action of relay 12. While larger average clutch command signals will cause greater current ow through the filament halves, the heating eifect averaged over several seconds tends to equalize. This equalization means that the same heating occurs in both filaments, which results in equal plate currents through the tube halves. With equal plate currents through the tube halves no differential action of coil 4 of relay 12 will occur, and undesired tripping of the alarm is prevented.

Figure 2 indicates a system for connecting a combina- Ytion of vthree of the control circuits of this invention together with one alarm indicator, and applying them to a single three-axis automatic pilot system. The clutch signals are `applied -to and Aoperate on c ach of the tubes 2,1, 22;, and I23yexac't'ly as they operated on tube `11 in the above description. One voi the tubes, 21, is rudder controlled; Aanother tube, 22, is for the aileron 'control circuit; and the lastY tube, 23, is for the elevator control circuit. It is to be noted that 'the alarm circuit is con nected to the cathodes of all three tubes so 'that- Yone alarm circuit may show faults in any of the chosen command circuits. i f The .gaseous tubes 16 are optional,` and are used in the plate circuits of the tubes Il paralleled by the load resistors 17' to .provide quick or snap action when 'the current flow iti/)the .plate circuit attainsa certa-in fvalue of..potential. This results ina sudden increase of-cirrents inthe -cathode circuit due to the conduction of the tubes v I1. This increase in current flow beyond the danger point reduces the hesitation and false operation of diifer'eritial relay n1-2. VThus,lwh`en the command signal is clearly erroneous, the ionization of tube 16 permits the quick soundingk of the alarm circuit of this invention.

Although this Ainvention has been described with respec't to `a particular embodiment thereof, it is not to be so. limited, as changes and -modiiications may be -m-ade therein which are within the full Iintended scope ofthe invention as defined by the appended claims.

What is claimed is: l I ur l. ln an aircraft autopilot system of the type including directional control signals, anY amplifier for-amplifying saidcont'rol signals and clutch means including clutch driving coils and monitor means for controlling the ontput from `a drive motor which positions the night surfaces of 'said-aircraft in response to said control signals; a^rnalfunetionrnonitoring system comprising electron discharge means including. at least two plates, two cathodes and two heater elements, each of saidV clutch driving coils individually serially connected through one of said heater elements to said control signals, a differential current-sensing means, said cathodes connected to opposite ends of said differential current-sensing means, a source of electromotive force vhaving one side connected to said plates andthe other side connected to thev center of said current-sensing means,l switch meansl responsive to differential current fl'o'w in said differential current-sensing means, an kalarrnfdevice and a: source of ,power connected to said alarm device by. said switching means when a differential current flows 1in said differential current-sensing means. r2. In an aircraft autopilot system of the type including directional control signals, an amplifier for amplifying said control signals, and clutch means including clutch driving coils and monitor means for controlling the output from a drive motor which positions the flight surfaces of said aircraft in response to said control signals; a malfunction monitoring system comprising an electron discharge device having at least two plates, two cathodes and two heater elements, said driving coils individually serially connected through said heater elements to said control signals, a differential current-sensing means comprising a center-tapped coil, said cathodes Vconnected to opposite ends of said differential current-'sensing means, a source of electromotive force having one vside'co'rir'ie'iited to said plates and the other side connected to' the center tap of `said coil, lswitcl1 means responsive to differential current flow in said differential entrent-sensing means, an alarm device and a source of power connected to said alarm device by said switching means for providing warning signalsA when 5a Vdifferential current flows `in -said differential current-'sensing means sufficient of value' to ac tuate said switch means.

V3. vInan aircraft autopilot system of the type including directional vcontrol signals, Aan amplier Afor amplifying said control signals,- fand clutch means including Vclutch driving coils and monitor means for controlling the outputffrom a motor means which controls the flight of said aircraft in 'response to said control signals; a malfunction monitoring system comprising an electron discharge'edev-ice having at least two plates', two cathodes ,and two heater elements, said clutch driving -coi-ls individually serially connected through said heater elements to `said control signais, a differential current-sensing means conn prising a center-tapped coil, said cathodes connected to opposite ends of said differential current-sensing means, fa source of. `electomotiv'e force having one side connected to Yeaeh"of1saicl .pla-tes through identical circuits comprising Ya-resistarnze and a fgaslled electron discharge device connected in parallel,` switch means responsive to apre` determined value of differential current -ow Yin said differential current-sensing means, an alarm devicel anda source of power connected toy saidV alarm device by `said switch-ing means forpi'oviding warning signals when'l a prescribed' 'differential current is owing in said: differential current=sensing means'.

References Cited in the -file of this .patent ''tni STATES PATENTS

Patent Citations
Cited PatentFiling datePublication dateApplicantTitle
US2662207 *Jan 7, 1949Dec 8, 1953Bendix Aviat CorpAutomatic steering system with displacement limiting means
GB671912A * Title not available
Referenced by
Citing PatentFiling datePublication dateApplicantTitle
US3054097 *Dec 30, 1958Sep 11, 1962Textron Electronics IncClipping indicator
US3988713 *Mar 5, 1975Oct 26, 1976Sundstrand Data Control, Inc.Aircraft ground proximity warning instrument
Classifications
U.S. Classification244/194, 318/565, 318/489
International ClassificationG05D1/00
Cooperative ClassificationG05D1/0055
European ClassificationG05D1/00D