US2496294A - Speed governing system for dirigible craft - Google Patents

Description

m N p n fumaba, Wp E295@ s. mmummn AQML SPEED GOVERNING SYSTEM FOR DIRIGI'BLE CRAFTS Filed Dec. 29 1944 ATTORN EY Patented Feb. 7, 1950 SPEED GOVERNING SYSTEM FOR DIRIGIBLE CRAFT Spencer Kellogg, 2nd, Glen Head, N. Y., assignor to The Sperry Corporation, a corporation of Delaware Application December 29,1944, Serial No. 570,408

15 Claims.

l This invention relates to a system for governing the speed of movement of dirigible craft such manifold 4 is made for the corresponding part of each of the engines 2 and 3. The prime movers as aircraft by controlling the prime mover or prime movers thereof. As particularly adapted to aircraft, the system is eifective to automatically maintain the craft at a substantially constant desired air speed whether the same is flying straight, yawing about a vertical axis, or tilting about either its pitch and/or roll axes.

According to the present invention, the throttle valve or other means for changing the condition of operation of the prime mover controlled by the system is operated by means controlled by the compared signals of a pick-nii positioned by a speed responsive device and a second pick-off controlled by the position of the throttle valve or other means. The signals are compared in a receiver whose output is zero when the signals are of opposite and equal amplitudes. When the signals are unbalanced the receiver is effective to produce an output that controls the move-A ment of the throttle valve in a directionto restore the signals to balance. Where more than one engine or prime mover is controlledby the system, the throttle position of the controlled throttle valve of the primary engine is employed to provide a base for a repeater control device that similarly positions the throttle valves of the other engines.

A further feature of the invention resides in inclusion in the system of means for damping the movements of the automatically operated engine controlling throttle valve. Means for damping the throttle valves of each of the engines are lncluded in a multi-engine controlling system.

Other novel features are hereinafter more par`" condition of operation of engines 2 and 3 respectively include carburetors 'I and` 8 and throttle valves 9 and I0. A showing similar to intake may be conventional gas engines. as employed to provide the motive power to move `dirigible craft such as aircraft.' The engines per se are not considered an element ofthe system and are consequently neither specifically shown in the draw-A ing or positively set forth in the claims of the application. l

As shown, the system includes a meter or device adapted to measure the speed of movement of the craft through the air. Such a device is depicted in the drawing as including a Ptot tube I I whose head-on pressurels dependent on the speed of travel of the craft plus the pressure at the night level of the craft anda Pitot-static tube I2 whose pressure is dependent only on the night level of the craft. Arrow I3 in the drawing indicates the direction of travel of a craft with the meter thereon. Tubes II and I2 connect with an airtight body I4 having a central diaphragm I5 therein so that the respective pressures supplied are in opposite sides of the diaphragm and determine its `position in the body I4. As shown in the present case, diaphragm I5` is operatively connected to a shaft I6 by means of reciprocating piece I1, and a linkage which includes rocker I8 and connected links I9 and 20. The meter illustrated is corrected for change in air density with altitude change by a closed bellows 2I which presses against one end of the rocker I8. Link I9 of the linkage is temperature sensitive so that the meter is corrected for variations in temperature conditions under which a craft having this instrument thereon may operate. A meter having these corrections may be termed a true air speed meter.

' Shaft I6 of the meter is positioned by the diaphragm I5 in the present instance through the flexible cable connection 22 which is secured to one end of the link 20. Coil `spring 23 for the shaft I6 maintains the cable taut. Shaft I6 moves in one direction when link 2li pulls the cable as reciprocating piece rises as viewed in the drawing due to a decrease in the air speed of the craft or to an increase on the static pressure head. The shaft moves in the opposite direction when permitted by the linkage by means of the spring 23.

` In the present instance, the shaft I6 of the device responsive to the speed of the craft controls a pick-olf indicated at 24 to produce a signal that amener corresponds to the crafts speed. As shown, pickoff 24 is a two phase Selsyn instrument whose wound rotor 25 is positioned by the shaft |6. The rotor of this electrical pick-oi is supplied with energy from a suitable source of alternating current designated at 26. The other part of the pick-off 24 is a stator 21 whose respective windings are electrically spaced by 180 degrees. The stator part of the twopart electrical pick-oit is rotatably mounted to move relative to the rotor thereof under control of a setting'knob 28 that is manually operable. designed to produce a linear signal output above or below a desired reference speeddetermined by the setting of knob 28. When the speed of the craft is above that desired by the reference, the voltage output or signal is..of .one polarity or phase while when below that desired is of the other polarity or phase. When the craft is moving at the desired speed, the'output or signalvfrom pick-oli 24 is zero. The signal of pick-off 24 is fed to a receiver hereinafter described by way of leads 29 and 30.

`The-improved system also includes a second pick-oli `3| Awhich is shown in the present instance as of the same general character as pickoif 24. The Vrotor 32 of pick-off 3| however is operated by and kpositioned-in accordance with throttle valve' 'of engine asY these Velements are xedly 'mounted on la common shaft 33. The rotor winding of the pick-off is energized from A.V C. source 26. The phase wound stator 34 of this pickofi may also be rotatably mounted and set in position byamanually controllable knob 35. Knob `35 determines the base setting for the throttle valve Sat which the pick-'off 3| has a The pick-oit is primarily respective pick-offs or with signals from the pick offs that are 180 degrees out of phase and of equal amplitudes. The receiver in such event has no output. When signals are fed to the receiving circuit by the pick-offs that are not completely balanced across these respective resistors, the circuit provides an output signal that is fed by way of lead 44 to a phase sensitive amplifier 45 of conventional form whose output is directly fed to the "control winding 40 of the noted polyphase induction motor.v The throttle valve is moved by the motor as is the rotor of pick-oil' 3| in a direction that restores the receiving circuit for Vthepiclt-olf to a balanced condition with zero output. The receiver thus compares the .signals of the pickoffs in opposing relation and l.provides an output -when the amplitudes of the respective signals are unbalanced. The amplified resultant of the signals of the pick-offs de- Itermines thefdirection'of rotation of the throttle movingmotor which continues to move in the zero output. When to either side of this desired v base, either the throttle'is morefully opened or closed, the pick-'oil is eiective to 'produce an output signal whose phase is dependent on the direction that the throttle has'moved in from its desired `base setting and whose amplitude is dependent upon the extentof .the displacement.

The system further includes means connected to operate the throttle valve 6 or other means for changing the'conditions of operationof the prime mover. As hereinshown this means includes Worm'Wheel 35 fixedly'mounted on shaft 33, worm 36 and `shaft`3'i which may be driven by a .conventional polyphase induction motor of the squirrel-cage 'type whose short-circuited rotor isindicated at 38. Stator winding 39 of` this motor is continuously excited by connection with source "26. 4U oi this motor is energizedto control its 'direction of .operation will be hereinafter described.

In accordance with the teaching of the invention,the system includes receiving means for the outputs of the respective pick-os 24 and 3| which itself provides an output for the'throttle operating means that .is eiective tomove the valve in a directionto restore the signals of the pick-offs to equal and opposite amplitudes and a balanced condition. The receiver as shown is a circuit, one end of which is grounded7 that includes resistor 4| across which the voltage of pick-off 3| is impressed land Apotentiometer 42. across which the vvoltage of pick-off '24.is im-A pressed. The adjustable arm 43 of potentiometer 42 is manually settable to modify the ratio between the signals of the pick-oils to obtainan output y.from the receiver. With the resistance of .each of the branches of `the potentiometer. equal and equal .to resistance 4|, the system isl normally balanced with zero signals from the The manner in which windingY same direction unitl the phase of the voltage signal fed the windingis reversed.

In operationthe systemtends to maintain-the craft at a substantially constant predetermined airspeed as aA change in air speedis immediatelyv reflected in the air speed meter to reposition shaft |6 and therotor `25 ofpick-oi 124. This either increases or decreases `,the output signal of the pick-off andunbalances the signal receiv' ing circuit of thesystem. VIf `the signal of'pickoil 24 increases, the motor is driven .to reposition' the .throttle suiciently to'balance the increase in the receiver by the increasedsignal frompickl oli 3| which closes the throttle and .reduces the'. speed of the craft. Reverse relations occur when the signal ofthe pick-off 24 decreases due to slowing. downvof the speed ofthe craft.

The. system further includesmeans for dampin g .the .movements .of the .throttle operating means. As shown, this means may be in the form of anA. C. generator'having a movable.

armature546,mounted .on shaft 31. The .generator further includes a stator .havinga winding 41 continuously excited by energy supplied Afrom,

source 26. The output winding 48 of the generatorror alternatoris connected tothe phase sensitive. amplifier 45, the signal thereof being fed in opposition .to .the .output signal ofthe .receiver circuit so as to dampthe operations of the motor at all times and keep the speed thereof in direct proportion tothe magnitude .of the controlling signal Vfrom the receivercircuit. The alternator provides an A. C..signal.means .formaintaining thezspeed of throttle operatingmeans in proportion to the dutputfsignaly of the receivingmeans.

When the'improved systemis rutilized tocontrol a .plurality.of yprime movers,.further means are included to position the respective throttle valves thereof in. accordance with the `controlled position .ofthrottle 6 of engine l. In .theinstant showing three phase Selsyn instruments49, 50 and 5| .are vemployed in this connection. The

rotor V52 of j instrument 7.4.9 isfxedly mounted on.

shaft ,33..an'd`is supplied with energy from source 26. the .position .of throttle valve. 6controlling engine instrument .5|

52 and stator v55, a signal is produced in the rotor It is understood that `shaft 33 determinesl 53 which i`s`fed `to phase sensitive `.amplifier 58 and to the control winding 59 of a motor connected to move the throttle 9'of engine 2 in the same way as hereinbefore described in connection with engine l except that in this event the throttle is moved until the shaft thereof is repositioned so that no output is obtained from winding 53. Damping means is provided for throttle 9 in the form of an alternator as previously described whose output winding is indicated at 60. Corresponding parts for throttle ID are respectively indicated at 6I, 62 and 63. In order to account for engine differences so that the same may be properly synchronized, the stators of instruments. 5E and 5I are rotatably mounted so the same may be adjusted by manually settable knobs such as indicated at 64 and 65.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a speed governing system for dirigible craft having a prime mover with a controllable throttle valve; means connected to operate the valve, a speed measuring meter, a pick-off controlled by said meter to produce a signal when the craft is above or below a predetermined reference speed, a second pick-off operated by the throttle valve to produce a second signal corresponding to the displacement of the throttle valve of the prime mover from a predetermined position, and receiver means for said signals producing an output when the signals are other than of equal and opposite amplitudes for said valve operating means effective to move said valve in a direction that restores said rst and second signals to equal and opposite amplitudes.

2. A system as claimed in claim 1, including means for damping the movements of said valve operating means 3. A system as claimed in claim 1, in which said rst named pick-off includes two relatively movable parts and manually settable means for positioning one of said parts.

4. A system as claimed in claim 1, in which said second pick-olf includes two relatively movable parts and manually settable means for positioning one of said parts.

5. A system as claimed in claim 1, in which said receiver means includes settable means for modifying the ratio of the signals of the rst and second pick-oils to obtain an output therefrom.

6. 1n an aircraft prime mover controlling system, the combination of, means for changing the condition of operation of the prime mover, a device for measuring the air speed of the craft, a pick-off operated by said device to produce a signal when the craft is above or below a predetermined reference speed, a second pick-off controlled by said operation changing means of the prime mover producing a signal corresponding to the displacement thereof from a predetermined position, a receiver for the signals of the respective pick-offs comparing the same in opposing relation and providing an output when the amplitudes of the respective signals are unbalanced, and means responsive to the output of said receiver for operating the prime mover conditioning means to restore the signals of said pick-offs to a balanced condition and thereby automatically control the air speed of the craft. 1 f '1. A system as claimed in claim 6, in'which said pick-offs are electrical, the signalsare A. C. voltages andthe output from the receiver is zero when the voltage signals are compared degrees out of 'phase and Sof equal amplitudes.

8. A system as claimed in claim 6, in which said pick-offs are electrical, the signals are voltages and said receiver includesa potentiometer settable to modify the ratio of the rst and second pick-offs to obtain an output therefrom.

9. A system as claimed in claim 6, in which said operation changing means for the prime mover is an electric motor, said system further including electrical means for damping the operation o said motor.

10. A system as claimed in claim 6, in which said first pick-off includes two relatively movable electrical parts and manually settable means for positioning one of said parts.

11. A system as claimed in claim 6, in which said second pick-olf includes two relatively movable electrical parts and manually settable means for `positioning one of said parts.

12. A system as claimed in claim 6, in which said air speed measuring device is compensated for pressure and temperature changes.

13. The combination of a dirigible craft engine throttle, means connected to operate said throttle to control the conditions of operation of the engine, a device responsive to the speed of movement of the craft, means for producing an A. C. signal controlled by said device when the craft is above or below a predetermined reference speed, means for producing a second A. C. signal corresponding to the displacement in position of said throttle from a predetermined base, and receiving means for said respective signal producing means providing an output for controlling said throttle operating means when the signals are other than 180 degrees out of phase and of equal amplitudes.

14. The combination of a dirigible craft engine throttle, means connected to operate said throttle to control the conditions of operation of the engine, a device responsive to the speed of movement of the craft, means for producing an A. C. signal controlled by Said device when the craft is above or below a predetermined reference speed, means for producing a second A. C.. signal corresponding to the displacement in position of said throttle from a predetermined base, receiving means for said respective signal producing means providing an output for controlling said throttle operating means when the signals are other than 180 degrees out of phase and of equal amplitudes, and means for providing a third A. C. signal for maintaining the speed of operation of said throttle operating means in proportion to the output signal of said receiving means.

15. The combination of, craft speed controlling means having a positionable element, a meter for measuring craft speed, a pick-off controlled by said meter to produce a signal when the craft is above or below a predetermined reference speed, a second pick-off operated by said positionable element to produce a second signal corresponding to the displacement of the element from a predetermined position, means for moving said positionable element, and receiver means for said signals producing an output when the signals are other than of equal and opposite i? i :amplitudes forupemting saidzmovlng means fto .'IJNIIIEDJBTATES PATENTS move said elementhin g. dir'ectinnha'a'estores Number Name lmate the Signals -Of Salti '.plCk-OS t0 n balanced 1,418,131 Curtiss ;May\'30 1922 @Onditm w A u Y 1,978,863 :Gregg etal. oen-30,1934 SPENCER 'KELLGGG 2ND- 5 l21113,'6'13 .sias sept.-1o,1935 y "2,159,142 Fshel May 23, 1939 REFERENCES CITED I2,160,194 Bates May 3o, 1939 n 2,191,250 Fisch-e1 Feb. 2n, 1940 The. followmg refelences are of .record inthe 12,273,022 ,Craneietal Feb. 17' 1942 me 'OHMS patent: 1 :2,311,642 crane et a1 Feb; 2s, '1943

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