US1784348A - Latitude adjustment for gyrocompasses - Google Patents

Description

Dec. 9, 1930. R. E. GILLMOR ET AL I A, 1,734,348

LATITUDE ADJUSTMENT FOR GYROCCMPASSES Filed June' 21, 1928 2 Sheets-Sheet l INVEN ramszzzaldffijimn. fi amfflegmefi 1930- r R. E. GILLMOR ET AL ,348

LATITUDE ADJUSTMENT FOR GYROCOMPASSES Filed June 21, 1928 2 Shets-Sheec 2 I/V VE N T055 1% imic/ffiz llno/r p i drzez'mz.

Patented Dec. 9, 193% UNITED STATES PATENT OFFICE BEGINALD F'. GILLMOB, OF WASHINGTON, DISTRICT OF COLUMBIA, AND RICHARD DEIMEL, 0F HGBOKEN, NEVI JERSEY, ASSIGNORS, BY MESNE ASSIGNMENTS, TO SEER-RY GYROSCOPE COMPANY, INC., 0F BBOOKLYN,-NEW1YORK, A CORPGRATIQN or new Yon]:

Application filed June 2 1,

This invention relates to improvements in gyroscopic compasses, especially of the liquid controlled type wherein a liquid, such as mercury, contained in pair of connected vessels on opposite sides of the gyroscope, is utilized as the gravitational factor. In order to keep the period ofthe' compass con stant in different latitudes,it is the practice to vary the gravitational factor and it has been the practice in the liquid controlled type of compasses to effect this by alteringthe capacity of the connected vessels, or more accurately stated, to alter the capacity of the co-nnected portions of the vessels (see patent to Harrison and Bawlings, No. 1,362,940, dated December 21, 1920, and patent to Reginald E. Gillmor, 1,709,395, dated April '16, 1929).

Certain objections have arisen in practice to this method of varying the gravitational factor because it is necessary after the partition has been moved, in the form shown in the Gillmor patent, for instance, to make sure that the mercury between the vessels is equalized before the auxiliary. connecting valve is closed. This is a-ditiicult procedure at, sea when the ship is rolling, because one can never be certain when the mercury has leveled itself. The object of the present in vention is to devise a method of'varying the effective gravitational moment of the liquld without the necessity of a subsequent leveling operat-ion. We have found after a number of experiments that the efiective gravitational torque of the liquid is substantially independent of the depth of the liquid present but is primarily dependent on the area of the free surface of the liquid and its specific gravity.

Accordingly, we propose to vary the free surface of the liquid to alter the gravitational factor without disturbing the capacity of the connected portions of the vessels. 2

Referring to the drawings in which several preferred forms of the invention are disclosed,

Fig. 1 is an elevation, partly in section, of a gyroscopic compass showing'our invention applied thereto. I i

Fig. 2 is a section at rightangles'to Fig;

LATITUDE ADJUSTMENTFOR GYROCOMPASSES 1928. Serial No. 287,215.

1 of the'sensitive element of the compass showing a modified form of the invention.

. Fig. 3 is a similar. view of a still further modification.

Fig. i is a section on line 44 of Fig. 3.

Fig. 5 is a view similar to Figs. 2 and 3, showing a still further modification.

Fig. 6 is a detailed end elevation of the outside of the vessel of Fig. 1, showing the Ineansfor maintaining the center of gravity of the gravitational element.

Fig. .7 is a sectional view of a mercury container showing a modified method of maintaining the center of gravity fixed by varying the level of the mercury.

Fig. 8 is a view of a modified method of shifting the weight for this same purpose,

Fig. 9 is a sectional view of the mercury container showing an automatic method of shifting the weight as the wedge is shifted for this purpose. 1

In Fig. 1 there is illustrated an ordinary form of liquid controlled gyro compass hav ing the gyroscope proper 1, vertical ring 2, and follow-up element or phantom 3. On said phantom is pivoted at 4 the framework 4, which supports, the vessels 5 adapted to contain the liquid for imparting the gravitational moment, the whole constituting what may be termed the gravitational element or ballistic. Said'vessels are shown as con-. nected by restricted tube or tubes 66, and the frame work is connected to the bottom of the'gyro compass by'the usual eccentric arm 7 whereby both meridian seeking anddamping properties are imparted to the gyro-' scope. To vary the gravitational factor we mount within each of vessels 5 a movable member 8 which operates to vary the freev surface of the mercury 9. In the form'shown in Fig. 1, the member, is in the form of a ,ver-

tically movable wedge having a tapering lower surface 10 adapted to engage the free surface of the mercury and to be lowered thereinto. It will be seen that as the wedgeis lowered into the mercury the free surface of the mercury will be gradually lessened and therebythe operative gravitational factor of the, compass decreased. For raising and lowering the wedge, we have shown which may beread in connection with a latitude' scale'12. Said stem is threaded in. a rotatable thumb piece 13 which may beturned to 'raise and lower the wedge. .It will be understood that there is a. like wedge 1n the vessel on the opposite side of the compass.

' The raising and lowering of the wedge,

however, changes slightly the center of p i is occasioned in the center of gravity within ity of the whole ballistic or gravitational element comprising the mounting 4: and the boxes 5 and connected zonta l axis 4-4 of the gravitation a]. element and able compensating weight'14-(-Fig :6) which is shown as raised and lowered by a cam rotatably mounted on't-he side of the vessel time on'the scale 12. I v.

' If desired, a means may be. provided to au-' 5 by means such as the graduated thumb piece 16. The weight is shown as provided with a downwardly-extending stem 17 having a roller 18 hearing on said cam. When adjustin the wedge, therefore, for change inlatitu e, the operator also f adjusts the' camql5 so that-the latitude graduations 16 on the disc 16 -read the same as the latitude graduatomatically shift theweight when the'wedge is adjusted vertically; shown inFig. 9. In this-figure the stem 11 ofthe wedge 8is provided witha disc 20 which engages a cam surface 21 of a plunger 22: Th opposite end of said'plunger engages oneend of the bellcrank lever 23 having at; the outer end thereof aweigl t fii'. It will readily'be seen that as the wedge is lowered frorn'th full line'to'the dotted line position that" the weight 24 will be 'raised' from the full to the dottedline position without further adjustment. By such means the center of gravity can be maintained approximately in the desired location.

'Sitill another form of adjusting the auxil i'ary'mass vertically is shown in Fig; 8 wherei in -a cam 15 rotatable in a horizontal plane 7 is shown for raising and lowering the weight 14;. Said cam is shown as mounted ontop Y of box and" may berotated by thumb piece 31, havingpinion 32 on the shaft therewhich engages teeth on the'a-nnular segof, meat 33-securedto the cam.

' Iii-case,'however, it is desired to maintain the"'center of gravity in 'exactl theprop'er position without the necessity oradjusting weights by cams or the like, the form of the inventionshown in Fig.2 may be employed.

In this figure themain'mercury' vessels are shown at 5'-5" with the usual connecting tube 6. In eachvessel is shown any suitable form of vertical movable wedge 8. In addiarts includingrthe, mercuryJ This is undesirable as we prefer to keep the center of gravity on the hOIlroscopea We, therefore, provide in" addition a means such as a'vertically shift-1 this purpose.

One such means is tion, we have shown auxiliary mercu vessels 2525{ which are not connected, ut in which are "provided similar but inverted wedges Qt -26. The wedges 8 and 26 of the 7 adjacent vessels are supported on a lever 27 the bracket 29. v 7 Instead of raising and lowering a weight on the system, we may provide auxiliary means for varying, the interior capacity of the "liquid'containers and'the'reby adjust the height of. the mercurywiththe raising and lowering of the" wedge." Such'a means is shown inFig. 7 wherein a set .screw'34, provided ith' a knurled head 35,*is provided for liqIuid level. I s

: nstead of raising and lowering a wedge to vary the free surface we may move a member" across the surface of the mercury for this Saidscrew is shown as threaded in the sideof each vessel well below the shown as slidably mounted in a'n'extension 37 i from each box, the plates, being mounted so that aportionof the same lies below the normal level ofithe mercury but with the top of theplateilying above such level. Byturning' thepinion 38 the plate may be advanced more or lessjacross the" surface of the mercury to lessen the free surface thereof and by With drawing the plate completely within its hous ingthe entiresurface of the mercury may be exposed. In addition to varying thes'urface' of the mercury, it should be observed that this method also varies the effective lever arm of the mercury, since the plate first covers the surface" of the mercury farthest from the center of support 44 of the gyroscope 1. This form of the-invention also shows the set armsystem'alonefor changes in gravitational moment. Such a form isshown in Fi' s. 3 and 4 wherein a plate 36 is mounted entirely within themercury container on a threaded its shaft 40; 1*Byi'otatingtheshaft the plate is 7 moved toward the center of the yroscope which variesthe position of the e ective'or free surface of the mercury and lessens the effective lever arm of the free surface therebv varying the gravitational factor. The center of. gravit'yofthesystem in this instance remains u'ncliaiigedwith respect to the horizontal "a xis i-4', so'that' compensating Weight claim and desire to secure by Letters Patent has the apparatus shown is only illustrative and that the invention can be carried out by other means. Also, while it is designed to use the various features and elements in the combination and relations described, some ofthese may be altered and others omitted Without interfering with the more general results outlined, and the invention extends to such use.

Having described our invention, what we 1. In a liquid-controlled gyro compass, means for varying the gravitational factor comprising a member adapted to engage the free surface of the liquid, and means for moving said member to different positions with respect to said surface to alter the free surface thereof.

2. In a liquid-controlled gyro compass, means for varying the gravitational factor comprising a member adapted to engage the free surface of the liquid, means for moving said member to different positions with re spect to said surface to alter the free surface thereof, and adjustable means for keeping the center of gravity of the system unchanged. q

3. In a liquid-controlled gyro compass, the

combination with the liquid containers, of a wedge-likev member movably mounted above the normal liquid level, and means for adjusting the height of said wedge in accordance with the latitude to vary the free surface of the liquid. 7 l. In a liquid controlled gyro compass, the combination with the liquid containers, of a wedge-like member movably mounted above the normal liquid level, a. vertically movable mass, means for adjusting the height of said we dge in accordance with the latitude to vary the free surface of the liquid, and means for adjusting said mass to keep the center of gravity from shifting vertically.

5. In a liquid controlled gyro compass, the combinationwith the liquid containers, of a wedge-like member movably mounted above the normal liquid level, a vertically adjustable mass, and a common means for adjusting the height of said wedge in accordance with the latitude to vary the free surface of the liquid and for adjusting said mass to keep thecenter of gravity from shifting vertically.

6. In a liquid controlled gyro compass, the combination with the liquid containers, means for varying the gravitational factor comprising a member adapted to engage the free surface of the liquid, means for moving said member to different positions with respect to said surface, and a means for adjusting the interior capacity of said containers to change the liquid level to compensate for the change in the center of gravity occasioned by the adjustment of said member.

In testimony whereof we have aflixed our signatures.

" REGINALD E. GILLMOR.

RICHARD F. DEIMEL.

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