US2501787A - Closure and contact for mercury switches - Google Patents

Description

March 28,-1950 IE. w. RICKMEYER CLosURE AND CONTACT FCR MERCURY SWITCHES v T 2 Sheets-Sheet l Filed Deo; 15, T945 WMM/'l Marcl 2S, 1950 E. w. RlcKMl-:YER

cLosURE AND CONTACT Foa MERCURY SWITCHES 2 Sheets-Sheet 2 Filed Deo. l5, l:L9-45 .8 7 .Z fofo Patented Mar. 28, 1950 CLGSURE AND1 CONTACT 'EORAMERCURY SWITCHES" Ernsti Walter Rickmeyer,l Berkeley,- Ill, assignon to leersernlilectrio Gompany, Bellwood, Ill., a. cernorationofflilinois Kppliczttionecember. 13, 19.45.Serial` No. 63.4;777"

provided With restrictedfopeni'ngs therein through'- Whicha conducting fluid! (mercury) maypass'.

2t Gla-ims;I (Cl. 200e-152').

j A: quantity' of mercury i'scontainecl` in one of v the chambers and under' certain conditions is adaptedv to'flowinto the second chamber through therestrictedipassagesin thepar-tition. An elec trical`- contact member projectsr into the shell through the open end thereof; andmeans"l are provided for hermetically sealingthis openiend oftheshell. Tliemercury bridges a gap between this first' contact member and a second'- contact so as toclose an electrical' circuit throughv the switch:` .Y The invention is concerned With-thefrst con tact memberf and the meansl for ner-meticaily sealing'tfieendof the'vswit'ch shell throughwhich this contact' projects.

K It'is anfobjectofthe invention to=provide-an effective arrangexnentl for sealing the endi ci? a rmercuryA switch shell of'this--typef-while ati-the 'same time providing a terminal' connection to thecontaot'member with a Very low eiectrical're` sistance'.L notherwords; the inventionlhas the diialf-pur-pose of? effectively sealing the. open. end of? theswitcli shell While `at thesame timeA praviding a low: resistanceA path tot the' mercury through this end ofthe shell. This isaccom:- plislfied very` eifectivelyv in a simple'and inexpene sive manner; and by means' that'k are readily. adaptable to mass production; methods.

` v"'Iflleiforegoingconstitute some"l of the principal objectsl off tideY present'. invention, and" others' will becomeapparent from areading ofthe following descrilzxtionV and' from the drawings,. ina which.

` Fig. 1 is a'vertical sectionaLviewtakenithrough acompl'etely: assembled z mercury: switch that eineu bodies one form; of; the;- present: invention;-

2t; is la: top, plan.y View of the: switch; shown im Figi. 12T Eig: 3: isi a, fragmentary verticali sectional: View correspcndingtoilig; 1i butshowingfa". diierent r embodiment of the invention;

' Fig. vhis a side elevational view. of'tiiefelectrical contact element shown inlFig. 3';

1 Fig.' 5 isa tcp plan"- viewfoffthef.elementshown iInFi'g.'Y 4.7.

2 6 iisf a vertical sectional" View takenthrougii' aucontactimemberrillustratng a slightly different form of? Contact element;

Fig: 'Fis-afbottom plan View of the device shown Fig. isv av fragmentary Vertical sectionall View corresponding to-A Fi'gz; but showing still anothen embodiment: ofvtheV inventiom: and

Fig. 9'? isaf. view. corresponding to Fig. 8, but showing' a diifrcntiembodiment ofstheinvention:

For. purposesr of' illustrationy specific' embodi ments offtl'ielinvention havezbeen selected; it be-y ing, recognizedi that? manyv different modifications Will occur to the man skilled in the art. Itisv in.- t'endedl that many of these` modications Vmay be made without departing from the scope ofthe invention.`

Referring tothe drawings', and particularly to Fig. 1`, the'invention is' shownnas applied to a men cury-switch, generally indicated at l5', andcomprisingv'a sWit-clrishell` lfthat` isl open at one end and is provided with' v an, annular.' shoulder IlA in;- termediate theA ends' of the'shell1 for supporting a cupellikef` time:L delay7 eleizfient i8; As shown,

`this cup:` t8 comprises sintered` metal: particles totheuppenend tliereoffthatis supported on the. i

topedgeofthelcup L8.v Acopper ring 24, provided WitlfizaLangexZ, isadapted to pass throughthe open sid'ezofthe; cup:` I with.. the; flange1n251resting onY the topzedgeiof thehun. Anbei. washer: 26 is` disposed;v onu the-flange 25, and: the shoulder; Z3 off contact Amember".r 2l? rests" ony this berf- Washer 25. secondfberrwasher 2l surrounds the 1 up per: end". of? the.` contactmemberf 2|l and restson top` offtheishouldei 235; Theifshell It. is crimped over: at; 2&1 onta; thelastt4 mentioned: ber washer 255'; and isfpressed;rmlyagainst this Washer" so as; to. I eifectix'zely: s'eali thecontaci'f.l member 2-.11 into tl'ieopern endotheishell IE.

This contactsmemberr 2:! is: maud-,ofa material that: has' theapropertyfof.: readily conducting, elec:- tricalicurrent. Abosselikex portion: 29,` indicated inbrokenslirres; is; initiallyprovid'ed at the,y upper end: cfr the? coc'rtact members 2| f, .and ,a copper: ring 30 is adapted to Iit circumferentially anclfsnugly about3tliis1boss'-like projection. 29. This boss-like projection 29 is'tiienA riveted'V over` asN show-1rV at .Si tovforrn am attacking? means to ir-mly secure the copper ring 30 to the contact member 2l, and to insure good electrical conductivity between this copper ring 36 and the contact member. The copper ring 30 is provided with a terminal extension portion 32 to -which a lead wire may be attached. A second copper ring 33 may be mounted concentrically about the lower portion of the switch shell I6, as shown, and a second lead wire may be secured to this latter ring.

A body of mercury 34 is shown disposed in chamber I9 so that an electrical circuit from the electrical conductor 32 to the copper ring 33 is completed through the conducting member 2I, mercury I9, time delay cup I8, and iinally through the wall of the shell I6.

If the switch shell is spun about an axis that is disposed above the shell I6 so that under the influence of centrifugal force the mercury 34 is forced against the bottom wall of the cup I8, the mercury will pass through the restricted openings between the sintered metal particles and flow into the lower chamber ZIJ. A certain time delay is required to pass this mercury through the bottom wall of the cup into the lower chamber 20 due to the fact that air in the chamber 26 must be displaced, and this air must necessarily pass in a reverse direction through the restricted interstices between the metal particles into cham* ber I9. As soon as the mercury has passed into chamber 26 in a sufiicient amount to lower the mercury level in chamber I9 to a position below the lowermost contact portion 22 of contact member 2I, the electrical circuit through the switch has been broken.

The arrangement shown in Fig. l insures an effective seal of the open end of the switch shell I6. It is important that air be initially evacuated from the shell I6 and at all times be prevented from leaking into chamber I9 in order to prevent the occurrence of oxidation to thereby insure at all times good electrical contact between the mercury and the contact member 2 I.

Since the entire contact member 2I, as shown in Fig. l, is made of metal, it is essential that all parts of this contact member be velectrically insulated from the shell I6 and the time delay cup I8. As shown, the ber washers 26 and 21 serve to insulate the contact member and to space the shoulder 23 thereof from the walls of the shell I 6.

It may be desirable to provide a contact member that is mostly non-metallic and that in itself is non-conductive. In Fig. 3, such an arrangement is shown, where a contact member, generally shown at 35, comprises a plug or end closure portion 36 of Bakelite, or like non-conducting material, that is molded about a cup-like or cupshaped electrical conducting element 31. This plug 36 is provided with an annular shoulder 38 that corresponds with the shoulder 23, previously described. The manner of sealing this plug 36 in the open end of the cup shell is in accordance with that previously described in connection with the contact member 2I of the rst embodiment of the invention. The cup-like or cup-shaped contact element 31 per se is shown in Figs. 4 and 5, and comprises an upwardly opening cup-like or cupshaped portion 39 having an upstanding lead or electrical conducting member 46 forI securing thereto an electrical conductor. The-entire contact element 31may be made of copper or some other such material having high electrical conductivity.

As shown in Fig. 6, a similar arrangement to that shown in Fig. 3 may be utilized, but in this instance a conducting element 4I,may be em- 4 ployed where the lower portion. indicated at 42, constitutes a ring rather than a cup-like portion 39, as shown in Fig. 4.

In Fig. 8, a somewhat different form of the invention is shown. In this instance, a plug 43 is employed together with a cup-like element 44 that completely encloses a downwardly project. ing boss 45 forming part of the plug 43. In this instance, the lower portion of the conducting element 44 is in the form of a cup 46 that is relatively deep and is flared as at 41. This ared portion 41 is contained within the body of the plug 43, as was the case with the plug 35 shown in Fig. 3. This plug 43, together with its downwardly extending boss portion 45, may be made of Bakelite, and, again, is provided with an outwardly extending annular flange or shoulder portion 48. This shoulder portion 48 is adapted to be supported on the time delay cup I 8 in the mercury switch shell I6. In this case, however, a. seal is eiected by an irregularly shaped copper ring element 49 that passes between the wall of the shell I6 and the side and lower faces of the annular shoulder 48. This sealing ring 49 has a. downwardly extending flange 50 that projects into the time delay cup I8, and also is provided with an upwardly extending flange portion 5I that is crimped inwardly upon the top surface of the shoulder 48. The upper edge 28 of the shell Il, in this instance, is crimped over onto the ring ange 5I and then this last named ange is curved backwardly against the crimped over portion 28 of the shell. In this manner, the open end of the shell I6 is effectively sealed. In this embodiment of the invention, the walls of the cup 46 are exposed to the interior of chamber I9, and are subject to be contacted by the mercury in this chamber throughout substantially the entire depth of this cup portion 46. Thus, in this form of the invention, a longer contact between the mercury and the contact element 44 can be effected than in the case of the embodiment shown. for example, in Fig. 3.

Fig. 9 illustrates still another embodiment of the invention. In this instance, the contact member, generally shown at 55, comprises a. metallic contact element, generally indicated at 56, that is supported by an insulating portion 51 of Bakelite or like material. This contact portion 56 is provided with a lower end portion 58 having an upwardly extending portion 59 of less diameter. The insulating portion may be molded circumferentially by the upstanding portion 59 of the contact member, and is provided with an annular shoulder 60 that serves in the same manner as the previously disclosed shoulders 23, 3l, and 48, for example. In this embodiment of the invention, the central portion 59 of the contact member 56 initially projects above the insulating portion 51, as indicated in broken lines at 6I, and a copper ring 62 is mounted over this projecting portion. This ring 62 is firmly held against the top of the insulating portion 51 by riveting over the upstanding portion 6I, as shown at '63. Good electrical conductivity again is provided between the ring 62 and the contact portion 56.

As in the case of the embodiment shown in Fig. l, the copper ring 24 with its outwardly extending flange 25 is provided at the open end of the time delay cup I8, the flange 25 resting on the top edge of the cup I8. A gasket 64 is inserted between the shoulder 60 and the shell I 6 and flange 25 of ring 24. This gasket 64 is provided with an upper portion 65 that is bent over onto the top surface of the shoulder GII.

and then the open edge 28 of the shell I6 is crimped over against this portion 65 of the gasket with sui'cient pressure to eiectively seal the open end of the shell.

The ring 62 corresponds with ring 30 in the embodiment shown in Fig. 1 and serves as one terminal connection to the mercury switch. A second ring 33 is provided, as before, to serve as the second terminal connection to the switch.

In this form of the invention, an electrical circuit through the switch is completed so long as the mercury is in engagement With the exposed surfaces of the lower portion 58 of contact element 56.

I claim:

1. A contact member for use in an open shell of the type described comprising an open cupshaped contact portion, an upstanding elongated conductor attached to the side Wall of the cup, a closure portion in said cup-shaped portion and projecting thereabove, said closure portion ncludlng an annular shoulder projecting laterally beyond the outer limits of the cup-shaped portion, the conductor passing through the closure portion and connecting the cup-shaped portion with means adjacent to the top of the closure portion for attaching thereto an electrical conductor.

2. In a mercury switch, a shell having an open end, an annular shoulder in the shell adjacent to the open end thereof, a Contact member including an end closure portion for the shell, and electrical conducting means projecting through the contact member into the shell interior, said contact member including an upwardly opening cupshaped member of electrical conducting material having outside surfaces exposed to the interior 0f the shell, and mercury in the shell for conducting an electrical current from outside the shell to the cup-shaped portion.

ERNST WALTER RICKMEYER.

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

UNITED STATES PATENTS Number Name Date 2,251,011 Bear July 29, 1941 2,265,681 Bear et al. Dec. 9, 1941 2,297,924 Trautman et al. Oct. 6, 1942 2,414,836 Rickmeyer Jan. 28, 1947

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