US2443595A - Deviation correcting means for magnetic devices - Google Patents

Description

June 22, 1948. F. D. BRADDON DEVIATION CORRECTNG MEANS FOR MAGNETIC DEVICES Filed Jan. 22, 1943 3 Sheets-Sheet 1 INVENTOR FIG. 2.

FREDERICK D. BRADDON jMLw/M HIS TTQRNEY l June 22, 1948.

F. D. BRADDON 2,443,595 Y `DEVIATION CORRECTING MEANS FOR MAGNETIC DEVICES Filed Jan. 22. 194s FIG. 3.

/l/lll/lllllllllllllllll 3 Sheets-Sheet l22 lllllllll/llllllllllll,

liminnr INVEN'TOR FREDERICK D. BRADDON ul'le 22,1948. F Q BRADDQN 2,443,595

DEVIATION CORRECTING MEANS FOR MAGNETIC DEVICES Filed Jan. 22, 1943 3 Sheets-Sheet 3 MAGNETIC DEVICE FIXED DEVIATION EFFECTS TEMPORARY DEVIATION t EFFECTS l RADIO RECEIVER TEMPORARY DEVIATIONy EFFECTS 2 ELECTRIC PILOT .IvENToR FREDERICK D. BRADDON Patented June 22, 1948 DEVIATION CORRECTING MEANS FOR MAGNETIC DEVICES vFrederick D. Braddon, Babylon, N. Y., asslgnor to The Sperry Corporation, a corporation of Delaware Application January z2, uns, serial No. 473,264

(ci. '3s-225)` 3 Claims.

A further object of the invention is to facilitate ready adjustment of the deviation correcting means for a magnetic compass of the type which may or may not be located at a remote position on the dirigible craft in which it is employed.

One of the features of the invention resides in the provision of coil means situated in the vicinity of the sensitive element of the magnetic device from which a controllable resultant corrective iiux eld may be obtained.

Another feature of the invention consists in provision of circuit means for controlling the respective deviation correcting coils for the xed source of local effects and each of the individual temporary and transient sources of such eiects.

A still further feature resides in the provision for making the circuit means correcting the compass for deviation due to a temporary local deviation causing attraction automatically eiiec tive.

Other objects, features and structural details of the invention will be apparent' from the following description when read in relation to the acompanying drawings, wherein Fig. l is a perspective view of a dirigible craft such as an airplane showing a magnetic compass system in which the present invention is incorporated.

Fig. 2 is a detail view, partly in vertical cross section showing one of the magnetic devices in which the present inventive concepts may be included.

Fig. 3 is a side elevation, with the casing in vertical section, showing the invention adapted for use in a repeater compass controlling type of magnetic compass.

ment of the magnetic compass may be sta.-4

Fig. 7 is a further circuit diagramshowing a practical adaptation of the invention in a craft oi' the character noted in Fig. 1 in which the controls for the respective deviation effects are situated in a single corrector panel.

In the form of the invention shown in Fig. 3, the magnetic compass instrument is oi the direct reading type that may be located on the instrument board panel l0 of a 'dirigible craft or airplane il, Fig. l.. This instrument is generally similar in character to the type ci magnetic compass shown and described in U. S. Letters Patent No. 2,300,404, issued November 3, 1042, to L. F. Carter and W. Anscott, with the remote reading features of the therein disclosed instrument eliminated. This instrument as shown in Fig. 2 includes a'casing i2 in the front owhich is a window i3 through which a side reading compass card ifi is visible to an observer. Card i@ is read in connection with a suitable vertical ex tending lnbber line provided in the present-construction by the forward portion o a bent rod it. The sensitive element of the magnetic compass is provided by two spaced permanent magnets, one of which is indicated at it, the same being responsive to the horizontal component of the earths magnetic eld. The magnets are spaced in parallel relation by means of suitable mounting pieces il contained in the body oi' the compass card providing casing i8. Card casing I8 is mounted for pivotal movementv about a vertical axis by means of shaft I Q which is supported in suitable upper and lower jewel posts in a vertical frame 2l). The rearward ends of the rod l5 are ilxed to the frame 20. It will be understood that the magnets i6, card housing Il with the side reading compass card thereon and the shaft i9 move as a unit with respect to the frame 20.

Frame 20 and consequently the sensitive eiebilized by Vmeans of a suitable gyro vertical instrument as generally indicated at 22. In the manner shown morel in detail in the hereinbefore mentioned patent, the frame 20 is universally mounted by means of a bifurcated mem- Figs. 4 and 5 are circuit diagrams illustrating the electrical connections for the lelements constituting one form of the improved. magnetic compass correcting means. l l

Fig 6 is a view similar to Fig. 3 showing the invention adapted i'or use with the sensitive element of a' iiux valve typeof magnetic compass, and

ber 23 that extends from and is :fixed to the gimbal ring of the gyro vertical. The extending arms of the member 23 have inwardly dis- -posed trunnions, one of which is noted at 2l that journal in suitable bearings 25 in the oppositely disposed legs of the frame 20. 'Iilt of the i'rame 20 about the thus deilned athwartship axis of horizontal support of the frame with reference tothe craft is controlled by link 26. Similarly dicular relation.

the fore and aft horizontal axis of universal support of the frame is provided by the bifurcated extension member 22 of the gimball ring of the gyro vertical instrument. The rotor bearing case and gimbal ring ofthe gyro vertical instrument are respectively indicated at 21 and 2l. The gyro instrument is of conventional iorm and is employed herein to maintain the sensitive element of the illustrated magnetic compass in a 'horizontal plane with reference to the earth's surface.

The deviation correcting means shown in Fig.

2 consists of a plurality of coils that are mounted within the casing or compass housing I2 with the y axes thereof arranged in fixed mutually perpen- In the form of the invention shown, coils of the Helmholtz" type are em-A ployed. The coil arranged in coaxial relation with the fore and aft axis of universal support of compassframe 20 is indicated at III. The coil at right angles to the same is provided by two spaced parallel coils 3|, only one of which is shown. Coils 3i are coaxial, in this instance. with the athwartship axis of universal mounting of the compass frame 20. lis shown, the coils may be connected to the inner wall of the casing or housing i2.

The coils of the correcting means are positioned adjacent the magnetic device or compass. and the respective axes thereof are arranged in spaced angular relation to one another in a horizontal plane, such relationship preferably y being as shown in the drawing.

In the form of the invention shown in Fig. 3, the magnetic compass is adapted for connection with a repeater compass which it controls, the sensitive element of the combination being located at a remote position on craft il such as at the'end of the wing of the same. The housing or casing of this instrument is indicated at 33 in Figs. 1 and 3. '.lhere may be one or a plurality of repeater compasses, one of the same be- -ing indicated at 34 on the instrument board panel I0 of the craft. A cable connection Il is shown linking the controller and controlled instrument which are described in detail in regard to the remote control features ot the aforementioned application. With reference to Fig. 3, the sensitive element of the magnetic compass shown therein comprises a bar magnet 0I which is mounted on the upwardly extending shaft 31 of the rotor of a selsyn" type transmitter whose .casing is indicated at Il. The transmitter and bar It are pendulously supported .within the housing Il by means of the gimbal ring 39 which also mounts the same for universal movement, the arrangement normally maintaining bar n in horizontal position. The compensating or correcting means provided in this instance include spaced pairs of coils oi -the Helmholtz type that are arranged sub` stantially coaxial with the bar, as viewed in Fig. 3, about its fore and aft axis of universal support. Paired coils Il', only one of which ,is shown, are similar to coils 3i previously described. In this form of the invention a further pair of coils 4i may be employed, the same being coaxial with shaft 31, as viewed in Fig. 3, and being also mounted within the housing or casing Il in a iixed location on the inner wall of the housing.

The circuit shown in Fig. 4 may be employed in the forms of the invention illustrated in both Figs. 2 and 3. As shown, a current source is lgenerally indicated at 42 which may be a battery,

the same providing a means for supplying the respective coils with energy from a common source. To control the polarity of .the coils, a common lead 43 is connected to a center tap position on the battery 42. Coil I0 or paired. series-connected coils 20' may be energized from the source by way of lead 44 and potentiometer 41. 8imilarly,supply leads 45 and 4l are respectively provided for the series-connected coils Il or Ii and for coils 4i. The energy supplied these respective coils is controlled by potentiometers 4l and 4l. The polarity and current in the reversible circuits thus provided may be ascertained by employing a suitable ammeter in the respective leads 44, 45 and 44. Such ammeters are respectively indicated at 15. 16 and 11. By adjusting the position of the variable arm of the potentiometers to either side oi a balanced central position, the energy supplied the individual coils is controlled in such a manner as to obtain a resultant ilux ileld from the vcombined coils that is effective to correct the sensitive element of the magnetic compass in this instance against any deviation thereof due to fixed deviation causing eilects. In accordance with the terminology employed herein, local ilxed deviation causing effects in the craft or airplane may be considered to be a resultant defleeting magnetic ileld due to the combined effect of al1 of the magnetic field radiating or attracting bodies tixedly incorporated in the structure of the craft. The same or a similar separate circuit may be employed for correcting a magnetic device of this character against deviation due to temporary sources of attraction such as may be considered to be caused by releasable objects on the craft such as bombs or torpedoes. The potentiometers 41, 4l, 4l provide a means for regulating the ilelds of the individual coils employed to obtain a resultant corrective flux ileld compensating the sensitive element of the magnetic compass against deviation thereof due to the resultant -of such local and/or transient fixed deviation from a re'lnotfv.- position is one of the primary advantages of the present invention. In the normal operation of a given craft, the potentiometers 41, 48 or ,41. 4l and 4l may be adjusted as required upon change of the temporary source of local attraction if the circuit is utilized in this connection. I'he invention also contemplates the utilization of the improved deviation correcting means for also correcting the magnetic compass for transient deviation causing local eil'ects such as resulting from a radio transmitter or receiver,special electrical equipment. or other mitter 50 is employed for illustrative purposes in this connection.

The magnetic device responsive to the hori-V zontal component of the earths magnetic ileld employed in connection with the form oi the invention shown in Fig. l6 is an earth inductor compass of the ilux valve type such as specifically shown and described in the copending application of Orland E. Esval, Robert S. Curry, Caesar F. Fragola and Lennox F. Beach, Serial No. 414,422 filed October 10, 1941,v for Flux valve compass system, which became Patent No. 2,383,461, issued August 28, 1945. The sensitivey element of the ux valve generally designated at 52 is pendulously supported within a housing 3l on a universal mounting provided by the gimbal ring 54, the output coils of the valve being situated in a horizontal plane withreference to the earth. Housing 33' is positioned as shown in Fig. 1 at a remote location from the repeater compass 3| which is controlled thereby, it being understood that the output of the valve is fed by way of cable 35 to the repeater compass. The exciting its and output coils of the ux valve are respectively indicated at 55 and 56. The correcting coil means 61, 58 and 59, 6D. A controllable circuit means similar to that previously described is provided for regulating the flow of energy to the coils 59 and B0, Fig. 5, to correct the output of the ilux valve for change thereof due to local xed and temporary deviation causing effects. As shown in Fig. 5, a second or auxiliary circuit means 'is provided to correct the output of the valve for deviation thereof due to operation of the radio transmitter 56 or other transient local deviation causing attraction which itself' may be energized when a switch 68 in series with the battery 42 is closed. The second circuit means includes, in thisinstance, the common lead 43, with the further leads 63 and 64 and potentiometers 65 and 66, respectively. It will be understood that the resultant field set up by the electromagnetsinuences the sensitive element of the iiux valve so that the output thereof is changed or corrected. A number of separate circuits, similar to the described second circuit, for each of the transient sources of deviation causing disturbances in the craft may be employed as hereinafter more particularly described. 'I'he compass or magnetic device is thus compensated for the described type of disturbances through the single correcting means. Once adjustment of the potentiometers 65 and 6 6 for a' particular or number of particular disturbing transient causes of deviation of the magnetic compass has been made, no further regulation may be needed and the circuits are automatically effective to obtain the needed correction from the compensating means upon closure of the switch to the particular or number of particular deviation causing electrical instruments.

It will be understood that the correcting means may also be utilized in connection with a compass of the rotary earth inductor type. Also, the compensating coils, ii desired, may be constructed for direct mounting on the pendulous portion of the compass instrument shown in Figs. 3 and 6 or on the stabilized frame 20 of the instrument vshown in Fig. 2 with equal effectiveness.

rector panel II situated at the instrument board panel of the craft. In this instance, three sources of transient deviation causing effects are illustrated, the same being radio transmitter Il, radio receiver!! and electric pilot 83. The control panel Il includes ammeters and and a number of paired potentiometers with common lead 88. The pair of potentiometers l1 and 8B are employed to correct the compass against deviation due to xed deviation effects. Once the settingof these potentiometers is made the same will remain ilxed. superimposed on the xed correcting signal are further signals resulting from five other circuits in this instance, two of which compensate the compass for errors due to temporary deviation causing effects. These last circuits are controlled by the respective paired potentiometers Sii-96 and Si--Sl It for example, a separate deviation correcting circuit is provided for each of the temporary causes ot deviation, when a change occurs and the cause of deviation is no longer present, the proper circuit is restored to a balanced condition by adjustment of the potentiometers. This alters the supply of current to the coil or correcting means to recorrect the compass for the resulting change in the fixed and temporary deviation causing effects.

The other individual currents provide additional control whereby the supply of energyV tothe individual coils is regulated to correct the devicel Iagainst deviation 'due to transient locai deviation causing effects. 'Paired potentiometers 93--94 control the iiow of current to the coils when the electric pilot @il is rendered eiective by closure of the switch 65. A further similar control circuit is provided for the radio receiver 82 which includes switch @t and the paired potentiometers SS-iil. Potentiometers-Ql--t are -provided for the control circuit rendered effective by closure of the switch 68 for the radio Vtrans- .mi-tter 56.

The operation of the circ-uit illustrated in Fig. 7 should be understood from the following -brie description thereof. It will be noted thatthe battery lili is connected, under normal operating conditions, across the potentiometers @l through 92 and therefore that the setting of these potentiometers continuously controls the magnitude and direction of the resultant eld produced by the magnetic device 66.' The voltages derived trom these potentiometers control the magnetic device to correct for xed or continuously existing deviation effects. Assuming, however, that the switch 96 is closed, placing the radio receiver I2 in operation, the battery will then be connected across the potentiometers SQ Iand it therebyV impressing la voltage across both potentiometers. This circuit m'ay be traced from one side of the battery |01 through conductor |02, switch 96, and conductor |03 to the common connection |04 between potentiometers 99 and H10. The other ends of these potentiometers are both connected to conductor m5 which, in turn, -is connected to the other side of battery IUI. The vwipers of these potentiometers are adjusted to pick ofi a voltage therefrom of the correct magnitude Vand polarity sense, when applied to the magnetic device I0, as'lto vary the magnitude or the direction, or both, of the ileld produced by the magnetic device, and this change will necessarily be of a fixed, 4predetermined value only,

whereby to correct ior the deviation error otherwise caused by the radio receiver on the magnetic compass. The wiper oi' potentiometer l0 is connected to conductor I which .through ammeter I4 is connected with one coil o! the magnetic device 80, and the wiper of potentiometer |00 is connected through conductor |01 in a similar manner to another coil of the magnetic device. The common return lead 80 from lthe magnetic device is connected with jumper |00 which is connected between preferably the mid-points of the two potenticmeters 99 and |00. It should be evident from the foregoing that the circuit oi Fig. 7, so iar as it relates to one of the devices providingl .temporary deviation eilects, is quiteY similar to the circuit illustrated in Fig. 5. Adjustment of the wipers of these potentiometers will determine the polarity sense of the voltages applied to the coils embodied in the magnetic device, and also the magnitudes thereof. Further, it will be observed that the switch 96 functions as a common means for connecting and disconnecting the battery with the potentiometers 99 and |00 with on-oi control of the temporary deviation-causing apparatus. By operating the various switches 60, 95 and 95, the respective poten-tiomete'rs associated therewith lwill be rendered operative and inoperative to control the magnetic iield developed by .the magnetic device 00.

It is to be understood that the term "magnetic compass as employed in the appended claims isintended to include all devices which are sensitive to an external magnetic field such. for example, as compasses comprising ileld-sensitive magnetic needles or those ofthe flux valve type which provide a'signal voltage output as an` indication of the direction of an external tleld relative thereto. Y

Since many changes could be made in the above construction and many apparently widely dii'-v ferent embodiments of this invention could .be made without departing from the scope thereof, it is intended .that all matter contained in the above descriptionor shown inthe accompanying drawings shall be interpreted as illustrative an not in a limiting sense. Y

What is claimed is:

1. In a system for correcting for' deviation ef` fects of a magnetic compass, the combination Vwith an intermittently operable deviation-causeV ing apparatus and a magnetic compass mounted in subjective relation thereto, of a plurality jof relatively angularly disposed coils mounted in cooperable relation to said compass, means for providing a continuous and controlled energization of said coils to thereby provide a magnetic ileld of a nrst predetermined intensity and direction to compensate the compass for local'xed deviation-causing effects, `means for additionally controlling the current flow respectively in all of said coils to subject said compass to a eid of a second xed and predetermined value in magnitude and direction substantially equal and with an intermittently operable deviationcausing apparatus and a magnetic compass mounted in subjective relation thereto, of means comprising three coils having their axes arranged in mutually perpendicular relationship and in cooperable relation to said compass. means for providing a continuous and controlled energization of said coils to thereby provide, a magnetic ileld of a ilrst predeterminedintensity and direction to compensate the compass for local fixed deviation-causing efiects, means for additionally controlling the current ow respectively in all of said coils to subject said compass'to a eld of a second fixed and predetermined value in magnitude and direction substantially equal and opposite to the combined magnetic eil'ect of said apparatus and the local relatively anguiarly disposed coils mounted in cooperable relation to said compass, means for providing a continuous and controlled energization of said coils to thereby provide a magnetic iield of a iirst predetermined intensity and di rection to compensate the compass for local xed deviation-causing eii'ects, means for additionally controlling the current iiow respectively in all of said coils to subject said compass to a ileid of a second fixed and predetermined value in magnitude and direction substantially equal and opposite to the combined magnetic effect of said apparatus andthe local fixed deviation-causing effects on said compass, and a common means for controlling the operation of said apparatus and the operation of said means for additionally controlling the current ow respectively in all of the coils whereby simultaneously to change the value of the magnetic iield developed by said coils from one value to another when said apparatus is turned on and off.

FREDERICK D. BRADDON.

REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS VNumber Name Date 41,839 Gisborne et al. Mar. 3, 1864 1,596,639 Vion Aug. 17, 1926 1,892,826 Bettison et al. Jan. 3, 1933 2,053,154 La Pierre Sept. 1, 1936 2,300,404 Carter et al Nov. 3, 1942 2,324,718 Noxon July 201943 FOREIGN PATENTS Number UCountry Date 13,752 "Great Britain 1896 356,844 Germany 1922 666,594 Germany 1938 OTHER REFERENCES Knotts Catalog of Scientific Instruments (1921).

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