US2431964A - Mercury switch - Google Patents

Description

Dec. 2, 1947.` EQWQRICKMEYER 2,431,954

MERCURY SWITCH Filed Oct. 11, 1945 ZPL 0W or@ TIME Patented Dec. 2, 1947 U 2,431.3-964,y MERCURY SWITCHI to 'Jeirson Electric ACompany-5,Bellvt"oo"cl', "Illll corporationof Illinois 1 Applications Octobrll, 1945, Serial No. 621,813

9 ,Y (Cl. ZOOLSOY i The present-.il inventiorn relates` tot.; mercuryt; switchesl of;=.i`the!:type Where 1a fswitch-zenvelopa-rf at leastiini iefect,fis.provided @with ,two 'chambers f adapted alternatively to receive and holdfia body ofi-"mercury: Oneofpthe chambers istprovided with .aztwo .electricalncorrt'act fmembers' insulated. fromz'each :other and electrically communicating;v with-the,interioruof;thevchamber. .The body of'. mercury ,while inizthisechamb'er bridges these two f membersh so asttoi. complete; the :electrical circuit through the. switch. f Upon proper: manipulation of the switchpthe. mercuryfislfcausedto move into i. the second chamberzso#as,tofbreak.theszconnecf tion` between the: "electrlcali ContactA members, therebyopening; the- Ycircuit through the -switchrf In ysomey types` 'of v(mercury switches' that' :haven beenrdeveloped,ithe two chambers are-separated byz-a wal-l for :partition f thatf. is :provided :with restricted passages, fori: otherfsuchy means,.;through which the mercurydlowsmin :passing from one chamber. in-tothe' 'other.;- Thefmercury is caused; Y

to l owe from one.V i chamber#v Sinto vthev other by centrifugal force:fresultingf=from rotating. or spine ning-4 themercury' switch.:`

The lswitch forming theffsubjechm'atter of the" presentinventionf entirelyeliminates-the use of.: the-,partition'and 'the-.orice; and provides a mer.- I cury switch thatf is :ideally vhsuited-i or centrifugal switches operated by slowlyffrotatingior spinning:` theswitch envelope `to. oreateth'e centrifugal force. Because iof theelow-frate'- of vvspin, however, thev centrifugalq forceV that :isravailable' is :such-:as ito. e. create "consider-able#problems -wliere-fthe1 :perfo--;l rated partition is used to.;t separate the` two chambers.

It is aan object of the; presentinvention :to pro` vide-a @mercury switch" thatis ideally suited fori low spin operation-and-1that "is relatively-ginex:A pensive andisimpleito manufacture and assemble. .f

The presentlsw-itch is well'-sulted for applica- 4,0:Y

tions where accurateaftiming: inafdelayed action: circuit is Arequi-red. The time\'delay-,character istics zof. this yswitch canbe pre-'determined withinA .f

veryy close limits The foregoin'g-fconstitutez.somero 4the `principal;y 45t objects and: advantages-ofthe present invention; p

others of iwhich AwillV become apparent fromirthe'E following description and the drawings, in which.:

Figa 1 is` a vertical sectionalfviewv through :a

completely.assembledmercury switch embodying-r 50;.

the:#presentsinventionyibut ,itis recognizedv that i many @variations :will :occur .toi/f the man skilled a in fthe-.art i and it .'is intended" vthat 1 these varia.- ation-s lmaybe emade without I departing: ',lfrom fthe: r' scopefof theinventionv.

Referring tofftheffdrawin'gs; f the; invention` is l' show-n in the-formof a mercurysswitch;genere: all-yindicate'd at. I 0,fthatfcomprises a switch :en-s velopefi I I; which lis.4 fdi-videdf into two-l chambersv t2 `andai 3 Tha-lower portion of the switch.' er1V velope I I hasz a freducedecross V-section,was` indi-l catedyA at Ill, to :provide-a shoulder 'I5 beneath: which. is mounted a'cond-uctingring rI 6 that makes, good electrical contactfwith'th'ewall of the switch:r envelope II.--. Boththe-switch envelope II andtheconducting: -ringl 6! are preferably madeof copper.

The-chambereIS that is-shownfinFiglas disi-. posed` :inf: the -lo,vverA part" lof the switch envelope: II is. completely -illed with-.a zslugil'lY of matee"v rial thaty is. providedfwithfa multiplicityof in-^` terstices orevoids?- This-slug Il mayl comprise sintered 'nickel or iron-particles: These particlesA are :smal-lv `.in .size;fand thevspaces between ad-ja-I: cent :particlesprovide "the necessary voids for receilvingV mercuryiromfthex upper :hollow chamber The lupper@ end or fthef'switch' envelope I I'V is' provided lwith .insulating members I8 and I9,r'over2f whichthewupperdedge of. the Aenvelope walliis: turned asiat 20.#Y Between thefinsulating..menrv ber/1 Seanct-the slugfd 'If isfa zcopper ring 42 Iii that; properlyfspaces -the insulating member I8"ffrom" the slug I1 and maintains the chamberIZ Ziree.k for accommodating .a bodyv of mercury, indicated at-22.. An electrically :conducting memberf23`` projectsy through zthe'insulating members il 8` yandi I QA `and 4into the' body: ori pooly =of mercury 22;1in: the .chamber '.'I 2. 0n top of the insulatingv mem"-v b-er .I 3-l and surrounding the :contact member=23 f is.-a---metal-ering.24,f-on topafofv which is mountedan electrically conducting ring25- that forms onei.. endet a conductor e261 The/contact `member123 isturned'foverfat itstupp'erend;asat2l,^so as to 1 hold the-ringsr24f-and725=rmly ini place' Thi's electricalwconductor a2$v--formszione `vcontact 'toll the. mercury'fsvvitchgaran'd Va Vse'condele'ctrical con-l l ductor (notfshown'). yis connect-ediv toetheucondufct# ing fringiI 6.-'.

UnderA normal conditions; a the mercury 2 2A comu plet-ely' frills chamber I 2.*ofwtl1eZ switch envelope; f

Fig. 3 .isa fdiagramvindicating `the: relationship-;55a` as shown' in fFigf..;1.r Thex-snteredfmetal4 slugv I l# is so organized and arranged that under normal conditions it is capable of supporting the mercury 22 in the chamber I2. By spinning the mercury switch Ii), or accelerating it in a direction so as to cause the mercury 22 to be forced against the Slug I'I as a result of centrifugal force, the mercury, given sufficient time, will flow from chamber I2 into the voids between the metal particles of the sintered slug II, thereby gradually emptying the chamber I2 to an extent suiicient to lower the mercury level below the contact member 23. Thus, the electrical circuit through the mercury switch, which initially passes from the contact member 23 through the body of mercury 22 and thence through the copper ring 2I and the wall II of the mercury switch I to the conducting ring IG, is broken.

At the beginning of the operation, which forces the mercury from chamber I2 into the voids in the slug I'I, the rate of flow of the mercury is relatively fast, because there is relatively free ow of air or gas throughout the voids, resulting in a rather rapid displacement of this gas. As the interstices between the metal particles are filled by the mercury, however, the flow of gas that is to be displaced is materially restricted, so that the rate of flow of mercury into the slug II is retarded. This relationship between the percentage of flow of the mercury from chamber I2 into the voids of the slug I1 and time is diagrammatically shown in Fig, 3 by the curve A. The start of mercury iiow is indicated on this diagram at the top of the curve shown at point 23, and it will be noted that during a relatively short time thereafter a rather large percent of the mercury flows into the lower chamber. The curve commences to flatten out at a point indicated at 29 so that the rate of flow decreases as the voids in the slug Il become lled with mercury.

It is thus seen that a time delay switch has been provided without the use of a wall or partition between the two chambers in the switch envelope and without the use of an orice that is the only means of restricting the flow of the mercury.

When the slug II is produced, it must provide ample voids within its body to accommodate or absorb the mercury that is initially contained in the upper chamber I2. Thi's, the volume of the slug I'I is much greater than the volume of the space that is provided in chamber I2. The time delay in breaking the electrical circuit, of course, is dependent entirely upon the rate of flow of the mercury 22 from chamber I2 into the voids in the slug Il, As soon as the mercury level in the chamber I2 is lowered to a position below the contact member 23, the circuit through the switch is broken.

During the assembly operation, the slug I'I is rst inserted through the upper open end of the switch envelope II. The sleeve or ring I2 of copper is set on top of the slug I'I so as to space properly this slug from the lower end of the contact member 23. The end closure for the envelope II is then completed with the electrical contact member 23 sealed in place.

This Contact member 23, as shown. is relatively short, though its length in its relationship with the chamber I 2 and the slug I'I will depend entirely on the intended use of the mercury switch and the time delay that is required. For a switch having relatively short time delay characteristics, the contact member 23 will be relatively short for given conditions of centrifugal operation, For high spin switches-that is, mercury switches that are operated in such a manner that the body 4 of mercury 22 produces a relatively great force against the slug II-the contact 23 will be relatively longer in order to provide a time delay in the breaking of the circuit through the switch. The displacement of gas in the voids or pores of the slugs II is caused by pressure of the mercury over the entire surface of the slug Il,

It is apparent from an examination of Fig. 3 that it is possible to select certain portions of the curve A for the limits of the switch operation. In other words, a switch can be adapted to function only over a fraction of the curve A by initially filling a certain percentage of the voids in the slug II. If this is done, the operation of the switch will commence at a lower position on curve A than the initial point indicated at 28.

Though sintered metal has been mentioned as the material from which the slug I'I may be made, it is recognized that this material may comprise a porous ceramic, or other materials which will provide the necessary porosity and yet will normally support the mercury in chamber I2 until the necessary centrifugal force is produced.

I claim:

l. A mercury switch comprising a switch envelope, a porous plug in the envelope adjacent to one end thereof, the opposite end of the envelope being substantially hollow, a body of mercury in the hollow portion of the envelope, and an electrode adapted to contact the mercury in the hollow portion of the envelope, the plug being adapted to absorb suilicient mercury to move the niercury out of contact with the electrode.

2. A mercury switch comprising a switch envelope, a porous plug substantially filling at least a portion of the envelope, a body of mercury in the envelope adjacent to the plug, and an electrode adapted to contact the mercury in the hollow portion of the envelope, the porous plug being adapted to absorb suflicient mercury to move the mercury out of contact with the electrode.

3. A mercury switch comprising a switch envelope, a porous plug substantially filling approximately half the envelope, a body of mercury in the other half of the envelope, and an electrode adapted to contact the mercury in said'other half of the envelope, the plug being adapted to absorb sufficient mercury to mcve the mercury out of contact with the electrode.

4. A mercury switch comprising a switch envelope, a porous plug in the envelope, and a body of mercury in the envelope adjacent to the plug, the plug being adapted to absorb a substantial amount of the mercury.

5. A mercury switch comprising a switch envelope, a porous plug in the envelope adjacent to one end thereof, means spacing the plug from the opposite end of the envelope, and a body of mercury in the space remaining in said envelope, the plug being adapted to absorb at least the major portion of the mercury. v

6. A mercury switch comprising a switch envelope, a sintered metal plug in the envelope adjacent to one end and spaced from the opposite end of the envelope, the said space being adapted to hold a body of mercury, and the plug being adapted to absorb at least a portion of the mercury.

7. A mercury switch comprising a switch envelope, a plug in the envelope and provided with multitudinous interstices, and a body of mercury in the envelope, a portion of which is adapted to enter and be held in the interstices.

8. A mercury switch comprising a switch envelope provided with a chamber therein, an electrode projecting into the chamber, a porous plug in the envelope adjacent to the chamber and spaced from the electrode, and a body of mercury in the envelope adjacent to the electrode and adapted to emerse at least a portion of the electrode, the plug being adapted to absorb at least enough of the mercury to move the mercury level in the chamber out of contact with the electrode.

9. A mercury switch comprising a switch envelope, an electrode projecting into the envelope, a sintered metal mass in the envelope spaced from the electrode, and a body of mercury in the envelope adjacent to the electrode and adapted to emerse at least a portion of the electrode, the sintered metal mass being adapted to absorb at least some of the mercury.

ERNST WALTER RICKMEYER.

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