July 29, ,605,452 E. P. NEY ET AL. Filed March 4, STABILIZING SYSTEM USING AN AMPLIDYNE

Transcription

1 July 29, 1952 E. P. NEY ET AL STABILIZING SYSTEM USING AN AMPLIDYNE Filed March 4, BY

2 Patented July 29, 1952 UNITED STATES PATENT OFFICE STABLIZING SYSTEM USING AN AMPLHDYNE. 1. The present invention relates to a stabilization System which makes use of the amplidyne. More Specifically, it relates to apparatus in cluding an amplidyne whereby devices, such as gun turrets, installed on a rolling or pitching Support, a ship, for example, may be kept steady in direction. The stabilization system consists, essentially of a free gyroscope, an amplidyne, a control circuit for the same, a direct current notor and a gear train. The primary object of the invention is to sta bilize a gun director against roll, and pitch. An additional object is to provide a device whereby the operator may control the motion of the di rector by a simple movement of a joystick, in Stead of manually moving the entire stand, thus relieving the operator of manual labor and allow ing him to concentrate his efforts and attention On the more vital features of his work. A fur ther object is to provide means whereby auto matic tracking of the target is made possible. Other objects and many of the attendant ad Wantages of this invention will be appreciated readily as the same becomes understood by refer ence to the following detailed description, when considered in connection with the accompanying drawing, the single figure of which illustrates the circuits and electrical apparatus involved in a preferred embodiment thereof. The Stabilization signals originate in a gyro Scope, not shown, having two pickoff coils, Which are connected in series-opposition, or "bucking' relationship, to the conductors 2 and 3, which feed the output of said coils to the primary Winding of a transformer 5. It Will be understood that the pickoff coils are traversed by alternating magnetic flux and are connected to the gyroscope to be moved in their own plane While in Said flux, so as to vary the voltages induced therein, as they move to include more or less of said flux.. There is introduced into the circuit a damping signal, here shown as a signal for an induction generator 56 of the "Kollsman' type whose out Edward P. Ney, Minneapolis, Minn, Frank L. Hereford, Jr., Swarthirrmore, Pa., Walter D. Whitehead, Jr., Old Church, Va., and Alden R. Kuhlthau, Durham, N. H., assignors to the United States of America as represented by the Secretary of the Navy Application March 4, 1949, Serial No. 9, Claimis. (C ) put is connected to the terminals of the resistor T, Which acts as a voltage divider by reason of the movable contact 8, so that any desired portion of the said generator voltage may be put in series with the pickoff coils í and winding 4, however, in such direction as to oppose the residual output from the coils. This Kollsman generator 56 is driven by the motor 9 which operates the turret to be stabilized. The output winding fo of the transformer 5 is center-tapped, as shown, and connected through wires. If, f2 and 3 to the cathodes and grids of a duplex triode, here shown as the tube 4 which may be of type 6N7. A resistor 5 is interposed in lead 2, and may be of the order of 2,000 ohms. The anodes of the tube f4 are connected through Wires 6 and 7 to the ends of the center-tapped primary winding 8 of a transformer 26, the said center tap being connected to the positive end of the power supply through the wire 9. The power supply is relatively simple, and corn prises a transformer 2 energized from 110 volt mains, and having the customary Secondary windings to supply electricity to tube filaments and heaters, as well as the high Voltage energy for the anode circuits. The rectifier 22 suitably may be of the type 523. A choke 2) and a capac itor 23 complete the power supply, which need not be well-filtered, inasmuch as it is not used for the reproduction of Sound. The secondary winding 25 of the transforiner 26, is likewise center-tapped. The center tap is connected by a conductor 27 to the cathodes of a pair of tubes 28 and 39, indicated as type 6L6, through the resistor SS, here : 1,000 i Ohms, andi transformer winding 34. The outer terminals of the Winding 25 are connected through Wires 32 and 33 to the control grids of tubes 28 and 23. In one of these wires, for example wire 32, two resistors 35 and 36, each of the Order of 5,000 ohms, are connected in series as shown, for a purpose to be described later, The transformer 3 introduces into the com mon grid circuit of tubes 28 and 29, an alternat ing voltage of the order of magnitude of volts. This voltage increases or decreases, the Voltage applied to the respective grids of tubes 28 and 29 accordingly as the Voltage across the Secondary winding 25 of the interstage transformer 26 changes phase. This renders the current through the amplidyne fields 4 and 42 a phase-sensitive direct current. The Screen grids of the tubes 28 and 29, are connected by the wire 3 containing three re sistors in Series, here each of the order of 25,000 ohms. The middle resistor has a slider 34 coop erating therewith as shown and connected by wire 38 to the terminal 39 forming the center tap between two input windings of an amplidyne, mechanically driven by the shaft 72 of a con stant speed motor 73, and also to the wire 24 which leads to the positive conductor 9 of the power supply. The anodes of tubes 28 and 29 are connected to said terminal 39 through the respective fields 4d and 42 of the amplidyne,

3 3. by way of terminals 43 and 44 and wires 45 and 46. Each field is shunted by a 0.25 m?. capacitor as shown at 47 and 48. The amplidyne is a highly specialized form of direct current generator, of the separately excited type. It has two pairs or sets of brushes, set 75 and ig being in the normal' commutation plane, the other brushes, 78 and 79, at right angles to said plane, in the electrical sense. The normal' set of brushes is short circuited by conductor 77, the other delivers the electrical output of the generator, which must of course be driven me chanically. The characteristic feature of Such a generator is that even a small external field will produce strong currents in the short circuited armature windings, thus setting up an intense flux due to the armature reaction. This flux is electrically at right angles to the field flux and is known as cross flux.' It becomes very intense when the brushes are short circuited because of the large currents that then flow in the armature WindingS. This cross-field in turn generates relatively great voltages between the brushes constituting the second set, which also constitute the output terminals of the generator. Thus a Small change in the field excitation input current causes a large change in the output of the generator. However, if it were attempted to draw current from these brushes, the cross-field thereby generated would : in turn oppose and annihilate the normal field. This is prevented by providing a suitably placed compensating field winding, traversed by the en tire output current, like the Series winding of a compounded generator. Due to the fact that the amplidyne is separately excited, the output of the machine is not self Sustaining, but is a function of said excitation, and ceases when the latter fails. When driven at a Substantially constant Speed, the amplidyne thus may be used to provide a relatively great response to a small input current applied to its field Wind ing. The power amplifications secured range from a few hundreds to Several tens of thousands, ac cording to the design of the machine. In the present case, the output of the two 6L6 tubes, 28 and 29, furnishes the variable energiza tion to field windings 4 and 42, and the ampli dyne generates, in response thereto, Sufficient power to operate the main turret motor 9. It will be understood that the polarity of the voltage generated by the amplidyne depends upon its field polarity and this in turn, through the electronic amplifier System, depends on the direction of shift of the pickoff coils,. Thus the gyroscope carrying Said pickoff coils controls the operation of the main turret motor 9, as to both the direction and the Speed of its ro tation. It will be noted that motor 9 is also a separately excited machine, hence reverses its direction of rotation when the Voltage applied to the armature changes its polarity. The output of the amplidyne 4C is connected, through its compensating winding 74, to the motor 9 to operate the latter, and the terminals 80 and 8 of the amplidyne are also connected, by means of conductors 52 and 53, to the corresponding ter minals and 5 leading ultimately to the grids of the tube 54. The motor 9, which has its field 5 Separately excited, as shown, drives the turret which is to be stabilized and also, through the mechanical connection indicated by the dashed line 55, operates the Kollsman induction generator 55. It Will be understood that the line 55 does not necessarily mean a single shaft, but in fact the Kollsman generator is reduced in speed in the ratio of 1:288 by Suitable gearing included in Said mechanical connection 55. An alternating cur rent is Supplied at low voltage to the input field 5 of the Kollsman generator, and the resulting al ternating output delivered from its terminals is fed to the terminals of the resistor T One of whose ends is connected to the wire 3, already described. Under the conditions stated, the voltage produced O by induction generator 55 will be proportional to the speed of motor 9, and its relative phase will be determined by the direction of rotation of Said motor. Through the wires 52 and 53 the voltage pro duced by amplidyne is led to the grids of tube 54, through the variable resistor 58 having the adjustable contact 59, and the capacitor 60 in Series. A Voltage dividing resistor 6 is bridged across the wires 52 and 53 and has an adjustable contact 62 thereon, connected to the cathodes of the tube 54, which preferably is a duplex triode although, of course, two separate triodies could be used if desired. An independent power Supply is provided for tube 54, as an ungrounded circuit is required. This is provided by the transformer 63 energized from the mains, and feeding center-tapped high Voltage from a Secondary Winding to the rectifier tube 64, here a 6X5. The filament or heater may be energized from an appropriate secondary wind ing on transformer 63 or on transformer 2 i, as preferred. The smoothing means for the rectified voltage consists Of the resistor 65, here 0 ohms, and two capacitors 66 and 67, each suitably being 15 mf. The high voltage direct current ouput has its negative terminal connected to the cathodes of tube 54 through the wire 68, while the positive terminal is connected to the anode circuit between the resistors 35 and 36, by means of Wire 69, which has a variable resistance 7 of the order of,000 ohms With the adjustable contact 70, in Series therein. The operation is as follows: Iet it be assumed that pickoff coils, are Shifted by the gyroscope, out of the neutral posi tion say, into the position illustrated, by reason of tilting of the gun director, due to pitch or roll of the ship. This shift of the coils f, will cause the lower one to have in an increased voltage in duced therein by the A. C. field, whereas the op posing voltage induced in the upper one is corre SpOndingly decreased. There now is an alternating voltage between conductors 2 and 3, equal to the difference of the two voltages just mentioned, and having a phase relationship or polarity always determined by Whichever pickoff coil voltage is the greater. In addition there is also the damping voltage be tween conductor 3 and the slider 8, which always opposes the Voltage differential of the pickoff Coils, regardless of its direction. This will be dis CUISSed later. The Voltage differential, thus decreased by the damping voltage, is applied to coil 4 of trans former 5, and duly amplified by the electronic tubes 4, 28 and 29 and the circuits associated therewith, with the final result that field 4 or 42 of the amplidyne receives a unidirectional ex citation from one or other of tubes 28 and 29, de pending upon the relative polarity of the A. C. Voltage applied to coil 4, and of a value propor tional to said voltage. This excitation will cause the amplidyne to generate a much increased D. C. voltage of a rel ative polarity corresponding to that of the orig

4 S inal differential pickoff signal, and of a relative magnitude, likewise corresponding to that of the signal input of coil 4. ; Inasmuch as the output of the amplidyne 4C, delivered from its terminals 80 and 8?, supplies the power to drive the turret motor 9, which is responsive to polarity, said motor 9 will operate in the proper direction to restore the turretto its desired stabilized condition, and at a speed com mensurate with the extent of the error from such condition. ' '',,? The Kolisman damping generator 56 mean while is providing a damping voltage proportional to the Speed of the turret motor 9, and always of Such polarity as to oppose the pickoff differential Voltage. This prevents overrunning, as the volt age fed to the motor 9 will begin to decrease be fore the said motor has finished its proper re sponse, So that the effect of mechanical inertia, is thus compensated. The power supplies, based on tubes 22 and 64 respectively, are or may be conventional and need no further explanation. The electronic tube 54 and is associated cir cuit have the purpose of preventing hunting. It Will be noted that the grids of this tube are con nected to the conductors 52 and 53 which lead to the motor 9. The capacitor 69 in the circuit pre vents any current flow through resistors 58 and 6. So long as the D. C. voltage between conductors 52 and 53 remains constant, but permits transient flow Whenever Said voltage varies. The resultant grid voltage fluctuations will produce correspond ing anode current pulses through resistors 35 and 36 which in turn produce varying voltage drops therein, that are fed to the control grid of tube 28. Due to the tremendous amplification between the pickoff coils,, and the output of the ampli dyne 49, instability would result at the normal Zero setting of the pickoff coils, in response to slight parasitic disturbances. Such instability, which would otherwise cause hunting, is offset by the compensating voltage pulses of the control grid of tube 28. Only one of the output, tubes need be thus compensated, thus simplifying the circuit. In order to prevent any disturbance of the nor mal bias of the said control grid, however, the tube 54 is of the dual type, and the respective anode currents thereof flow in opposite direc tions through the resistors 35 and 36, to eliminate the Voltage drops due to normal anode currents in tube 54. Adjustments are provided by the sliders 59 and 62, the former controlling the sen sitivity of the circuit, the latter serving to bal ance out any inherent differences in the two triodies constituting the tube 54. It will now be understood that by means of the apparatus described herein, any disturbances of the normally level position of the gun-director Support will in mediately produce a signal from the free-gyro pickoff coils, which, after amplifi cation, restores the support to its normal position by actuating the turret motor. Usually the Whole System is provided in duplicate units, one unit correcting for roll, the other for pitch, but in other respects being substantially identical With one another. Obviously many modifica tions and Variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described. 6 What is claimed is: 1. In a damping device for-a-stabilizing system, º comprising, a direct current drive motor-a gen o erator for energizingº said motor, a circuitº con necting the terminals of said motor and includ sing, in series, a variable resistor, a capacitor and a voltage-dividing resistor having an ad - justable contact, a pair of triode sections, said sections having their cathodes connected to each other and to said adjustable contact, and having their respective grids connected to the terminals of said voltage-dividing resistor, a center-tapped resistor having its terminals connected to the respective anodes of said pair of triode sections, a source of electricity having a negative terminal connected to said cathodes and having a positive terminal connected to the center tap of Said last-named resistor to supply anode power to Said triode sections, and a circuit introducing the voltage between the terminals of said last-named resistor into the field of said generator to control the output of said generator to Said notor. 2. In a damping device for a stabilizing System, comprising, a direct current drive motor, an amplidyne generator for energizing Such motor, a circuit connecting the terminals of said motor and including, in series, a variable resistor, a capacitor and a voltage-dividing resistor having an adjustable contact, a pair of triode Sections, said sections having their cathodes connected to each other and to said adjustable contact, and having their respective grids connected to the terminals of said voltage-dividing resistor, a center-tapped resistor having its terminals connected to the respective anodes of Said pair of triode sections, a source of electricity having a negative terminal connected to said cathodes and having a positive terminal connected to the center tap of said last-named resistor to Supply anode power to said triode sections, and a circuit introducing the voltage between the terminals of said last-named resistor into the field of Said amplidyne generator to control the output of said amplidyne generator to Said motor. 3. A stabilization system for a movable element, comprising, a free gyroscope to provide an alter nating current signal whenever the element dewi ates from its desired condition, Said signal being phased to correspond to the sense of said devia tion, means for providing a voltage opposing said signal, means for amplifying Said signal and deriving therefrom a correspondingly po larized unidirectional current, an amplidyne, said amplidyne having its field excited by Said current to generate a voltage of a relative polarity corresponding to that of said signal from Said pickoff coil and of a magnitude corresponding to the signal input, a direct current motor ener gized by said amplidyne and operatively mechani cally connected with the element to be stabilized, said motor being responsive to polarity so as to be operated in the proper direction to restore the element to its desired stabilized condition at a speed commensurate with the extent of error from such condition, means assisting in pre Wenting hunting of the motor, said means in cluding a circuit connecting the terminals of said motor and having, in series, a variable re Sistor, a capacitor and a voltage-dividing re sistor having an adjustable contact, a pair of triode Sections, Said sections having their cath Odes connected to each other and to Said ad justable contact, and having their respective grids connected to the terminals of said Woltage dividing resistor, a center-tapped resistor having

5 7 its terminals connected to the respective anodes of said pair of triode Sections, a Source of elec tricity having a negative terminal connected to said cathode and having a positive terminal con nected to the center tap of said last-mentioned resistor to supply anode power to said triode sections, and a circuit introducing the Voltage be tween the terminals of said last-mentioned re sistor into the stabilization system to constitute a component of the control thereof. EDWARD P. NEY. FRANK L. HEREFORD, JR. WALTER, D. WHITEHEAD, JR. ALDEN ER. KUHLTHAU. s 0. S 8 REFERENCES CITED The following references are of record in the file of this patent: Number Re. 16,667 1,679,354 2,115,086 2,432,302 2,478,3 2,481,5 UNITED STATES PATENTS Name Date Hewlett et al July 5, 1927 Fairchild et al. --- Aug. 7, 1928 Riggs Apr. 26, 1938 Fisher Dec. 9, 1947 McCoy Aug. 9, 1949 White Sept. 13, 1949