US2670421A - Roll type mercury switch - Google Patents

Description

Feb. 23, 1954 E, R, COUTANT ROLL TYPE MERCURY SWITCH 4 Sheets-Sheet 1 Filed March 29, 1952 l' H- Illini Inventor: Edward' H. Cout nt,

His Attor- Feb 23, 1954 E. R. com-ANT ROLL TYPE MERCURY SWITCH 4 Sheets-Sheet 2 Filed March 29, 1952 Inventor:

Edward F?. Coyt, His Attor ad.

Feb. 23, 1954 E'. R. COUTANT ROLL TYPE MERCURY SWITCH Filed March 29, 1952 4 Sheets-Sheet 3 Fg Inventor: Edward F2 ou a f' 'rl I f',

l-S Attor-n Feb. 23, 1954 E. R. couTANT ROLL TYPE MERCURY SWITCH 4 Sheets-Sheet 4 Filed March 29, 1952 Inventor:

Rl U

Patented Feb. 23, 1954 ROLL MERCURY SWITCH Edward It. contant, Stratford, conn., asssg'nor to General' Electric- Company, a corporation of NewYork Application Manch 29, 1952, Serial No. 2579-,294

V5' Claims.

This invention relates toelectric switches and particular to a new roll type mercury button switch.

By mercury button switchA` is meant that type of electrical switching devicecontaining. a mercury button rotatable to-an on or oit position.` conventionally a' mercury button comprises, aV pair of. r-netallicl shells, separated.1 by an insulating barrier. having a passageway therein.V When the meta-1 shells and, barrier are, rotated to. a, predetermined position, mercury stored between each shell; and the barrier. passes'through the passage- Way in the barrierto, establish electrical contact betweeny the shells and thereby act as a switching. device;V

In mercury buttonswitching devices ofr ay usual type, the mercury button-.isy nested. in a yoke having an operating finger extending through an. aperture in the; switch face plate.. The finger is movable to: rotate the button to anon andv ofE position where itisheld; by a detent ar.- ranglement.

i In these: switches, electrica-lY contact for con necting the switch in an electrical circuit is madegeneral'liy between the button. shells.- andf external pressure. contactsat the side of the, metalf shell with the pressure: contacts being locatect approxiw mately at` the geornetrioJ axis of. rotation of the shell. Such an contact arrangement within a, switch: of normal household` sizey limits the` spring pressure. that. can. be used t'he area ofr contact, and hence, the loadcarrying. capacity of the switch.

One. of. theI ohectives4 in: the; switch artis to increasethefloadcarryingf capacity ofv mercury lout-` toni switchesk and; one approach to:- this end: is` to increasefthe area. of contactiandfthe. contact. pres sur@betweenv ther button shellsvand external pressure; contactsfor a mercuryibutton.

. It is. an object or. this' invention therefore to provide a mercury button switch hav-ing am im` proved. contact arrangement, for engaging the mercury buttonv thereby to increase its load car-- vying capacity;

Itis: a. further objectfot this invention to pro vide a mercury button. switchI having. roll type trigger and improved:- contact.v arrangement;y Itis:I ai further objectJ of this invention to proa vide an improved. mercury button switchhaving, an integralhousing and faceplate:

It. ia a stillv further object. of this invention. to

provide.h a mercury switch. having; an integral` Further objects and' advantages of this inverte'4 tin Will bec'm apparent and the' invention will be more olea'ry understood' from the following de; scri'ption,l referring to the accompanying ii'ra'vv* ing, and the features of,v novelty which charactriz this invention will be' p'oiiit'ed out With particularty in the clfainis annexed t6 and' fri'n a part of thisspeeiiieation. Y

In the drawings; Fig; I is' a rear'- elevation of a three-way mercury button" Switch; Prat/ing'r an iri tegral race' pl`ate;"1ig. Zis a side'eievatiioriin seic= tion taken' along th'e1ine=2-2 of Fig; 1; Fig. 34 is a top view partly in section taken alongthe line 3--3' of 2; Fig. 4 S a' front elevation (reduced scarsi of the combination faceplateanti ron type switch shown in Fig; 1*; Fie. 5 is; anex-vv ploded; perspective view or the combination face plate and switch shown in Fig. 1; Fig. 64 is rear' ei'ev'ation of a second embodiment of thisjifiven@ tion wherein theVA face pi'ate andi the switch are separable Fig. is' a s'ideelevation partly in` secf tion' talien through the plane 1LT ofFig. 6'; Fig. 3f a` top 'view partlyinvsection' along* the line 8 8 of' Fig; 7:; Fig; 9 is a front elevation (reduced in sc'ale of the switch' shown in Fig. 6;L while Yii"ig'..l10` is' anexploitedi perspective' view' (enlarged s""c`:a'l\=i`)"`Y of the switch shownA in Figs; 6-'91 It` tobe noted that thesev figures' are not' al'l'dto the saine scale; but they have been eniarged or contracted as deemed"y necessary to pointjout as clearly as pfosfsihle'the' operating principles and' features'of this' invention.

Briefly thisx invention compri'sesy an arraneement involving the nesting of' a mercurybutton'L arolltype switch arm and; theuse of bottoni contacts' for" 'engaging the peripheral; surfaceor nient useclry merelyv as? an example: tof illust-rater` more clearly the eperatinggprinciples andfieatures ot thisr inventionv andi that it is not s@ cilepicteoly as: ay limitation onither scope of'thisinvenltion. A

'Ihefbody Zfmay be: madeitromi one: ofAV the Vpheif nolicv or urea resins or any other suitable insu* lating material approved for such use, and it is shaped to form a face plate II integral with switch housing I2. The switch housing is shaped to i'lt into an outlet box of conventional form and the face plate II is provided with suitable bores I3 for accommodating mounting screws for positioning the combination face plate and switch on an outlet or switch box.

The mercury buttons 3, 4 are of a conventional type as described, for example, in U. S. Patent 2,101,092 assigned to the same assignee as that of the present invention; but brieiiy each mercury button comprises (see Fig. 5) a pair of shells I4 and I5 made of some electrical conducting material, a glass ring i6 to form a seal while insulating the shells from one another, and a ceramic barrier (not shown) within the shells. The barrier has a passageway therein parallel to the geometric axis of rotation of the buttons and a pool of mercury is stored between each of the shells and the barrier sc that when the barrier is rotated to a predetermined position, the mercury enters the passageway and establishes electrical contact between the shell.

The spring contacts 5, 6 and 'I are a fundamental element of this invention in that they present something new in the mercury button art. Specically, the contacts or elements 5, 6 and I are made of any resilient electrical conducting material and they are constructed to establish an external pressure contact respectively between the peripheries of shells I4 and I5 of each mercury button and an external electric circuit. For example, in the illustrated embcdiment (Figs. l and 3) the strip 5 contacts the shell I4 of mercury button 3, the strip 6 contacts both the shell I5 of the mercury button 3 and the shell i5 of mercury button 4, while strip I contacts the shell I4 of mercury button 4.

The mercury buttons are inversely arranged so that when they are rotated to one position, electrical contact is established between two of the strips, for example strips 5 and 6, and broken between the other two strips, for example strips 6 and '1. When rotated to a second position, contact is broken between the strips 5, E and established between strips 6, l. For either switching action, the mercury runs out of the passageways in the barrier in one of the buttons and into the passageway of the barrier in the second button.

Each of the contacts 5, 5 and 'I as shown more particularly in Fig. 5 is made from resilient electrical conducting material, for example, Phosphor bronze, and formed to have a binding screw plate Il' or other wire connecting means at one end and a curved pressure contacting portion or bow I8 approximately midway of its length to engage the peripheral rim of one of the shells of the mercury buttons.

The housing portion I2 of the switch is slotted to accommodate the binding screw plate II. For example, nests I9, 2l) and 2l are slotted into the housing l2 to accommodate the binding screw plate I'I of the strips 5, 6 and 'I respectively. The housing is further provided with recesses as at 22 to receive the free end of the center contacts 6, thereby to provide a sturdy support for the contact to assure the pressure engagement with the peripheries of shells I5 of the adjacent buttons 3, 4. Shoulders 23 and 23a are also provided for the free ends of 'strips 'I and 5 respectively. With this structure both ends of each of the spring strips 5, 6 and 1 are supported to aiord a pressure contact between the strips and the mercury buttons.

A trigger 24 of insulating material is provided for the operation of the mercury button switch. The trigger is substantially semi-cylindrical and hollowed out at its center to provide clearance grooves 25, 2B to accommodate the glass seals I6 of the 4buttons 3 and 4 respectively. The trigger, in turn, is provided at each end with flange-like shoulders 21 having a stop 28 positioned thereon. A boss 29 complementary to shoulders 21 is positioned on each side of the housing I2 to support the shoulders and thereby guide the rotation of trigger 24. To limit the rotation of trigger 24, a slot 30 is notched in bosses 29 to provide limits for engaging the stop 28 to control the rotation of trigger 24.

.After the trigger 24 has been assembled into the switch housing with the buttons 3, 4 resting in the clearance grooves 25, 2B, then the spring contacts 5, 8, I are positioned to overlie the respective shells while the binding screw plates Il are positioned in their respective nests I9, 2U and 2|, whereupon a back plate 3|, made of any suitable insulating material, is attached to the back of the housing I2 and fastened in place by means of the screws 32.

The back plate 3l thus presses the free ends' of the contact strips down upon the respective abutments 23, 2'2, and 23a tensioning the bowed portions I8 or the several contact strips against the peripheral contact surfaces of the buttons. Thus, not only is a large contact surface areaA established, but also each contact is maintained under greater spring pressure than has been possible with prior art constructions. It will also be noted that in assembly of the switch, the contact strips, being the last elements to be placed in the housing, are never deformed away from the buttons and hence the contact pressure is uniform for all switches, thereby giving assurance that the contact pressure in the manufactured article will be of the value intended by the designer.

With this structure, it can be seen that the assembled switch may be installed in an outlet box with simplicity; that is, the binding screws 8, 9, I0 are at the top and bottom of housing I2 where they are easily accessible for wiring, and the housing I2 and face plate I I may be installed in one operation by passing screws through bores I3 in the face plate to engage an outlet box. Y

The front view shown in Fig. 4 illustrates a button or iinger rest 33 in the rotary trigger 24 to facilitate its operation. In one embodiment of this invention, luminous material such as a luminous tape may be placed over the outer periphery of the button so that the switch can be seen in the dark. Of course, some plastic surface coating might be put over the luminous material to protect it. f

The embodiment as shown in Figs. 6 throug l0 is substantially similar to that shown in Figs. l to 5 with the exception that in Figs. 6 through i0, a single pole switch is shown and the construction uses a separable face plate.

In the embodiment illustrated in Figs. 6 through 10, a housing 36 is providedwith face plate 3l and a backing plate 38. A rotary trig-v` ger 39 similar to that shown as 24 in Fig.,5, is provided with a hollow center for receiving a mercury button 3; that is, the center of the rotarytrigger 39 is hollowed out and bearing-like recep tacles 40 are provided at each inner axial end to accommodate the button shells I4 and I5 :maar

a suitable stop (not shcwnu ia provided the rotary. trigger 3a 'ta prevent relative movement between the. trigger 'andi the button when` thev twy have. beenA assembled. The: housing 3'6, like the: housing I2, is; provided with a bearing-like support or protrusion 4I for accommod'ating complementary ange-like mem bers. 4Z extending from either axial end of the rotary trigger 38.- The: flange-like members 42 have a stop 43 adapted to move withinthe limits of aJ gap.` 44 in protrusionsf 4iI1 to limit the rotation. of the trigger' 3i).v The lengthl ofv the gap is defined by shoulders 45, 46" which, are engageable with stop 43.

To assemble the switch, mercury button It is inserted into the. hollow rotary trigger 39i which, in, turn, is placed into the housing 38 witlr the stop 43 extending through` the slot 4`4=. Then spring contacts:` 41 and 48 which are similar to the spring contacts 5, 6 are inserted so that their binding screw plates 49, 5I!Y slide into-'registering nestsv 5I' and 5-2' respectivelyin housing 35. To provide for the interengagement between. the spring contacts 41., 48, and button shells I4', I5, the spring contacts, are bowed, as at. 53', to conform to the periphery of the shells I4 and' I5.

lt should be noted in this instance that the strips 41, 48 in addition to being supported at one end by the nests 5I and 52 are supported at their opposite ends by shoulders 54, 55 respectively so that the bow 53 is suspended for bias toward the shells I4, I5.

The backing plate 38 is provided with a barrel-like bulge 56 which conforms with the contour of button 3. When backing plate 38 is inserted in place and secured by screws 51, it presses springing contacts 41, 48 into engagement with shells I4, I5 of button 3 and holds the other elements of the button in assembled relationship.

Thus, as in the preceding modifications, with both ends of the spring contacts supported and with the back plate holding the spring contact ends in position, the bowed portions of the contacts will bear firmly against the button contact shell surfaces so that a desired degree of contact pressure can be achieved and maintained.

Also, because of the construction permitting assembly of a device from the back, no undesirable deformation of the contact strips will occur during assembly.

Housing 36, like conventional switches, is provided with a mounting bracket 58 having clearance bores 59 through which screws 60 may pass to secure the mounting bracket 58 and switch housing 36 to a switch box 6I. After the switch has been mounted in the box, a cover or face plate 31 may be attached to the bracket 58 and hence to the switch by means of some suitable screws 62.

It will be evident that the single pole switch arrangement of Figs. 6-10 may be used in the integral housing and face plate construction of Figs. 1-5, and conversely that the three-way switch of Figs. 1-5 may be constructed to have a separable face plate as in Figs. 6-10. Other modications of this invention will occur to those skilled in the art and it is desired to be understood, therefore, that this invention is not to be limited to the particular embodiments disclosed but rather is it intended to cover all modifications which are within the true spirit and scope of this invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l.y A mercury switch comprising an intimal face plate and body member made or' insulatmg materiali a rotary trigger forV operating the switch, al mercury buttonhaving a. pair or' cupshaped shell? terminals separated byv an vi'nsi-rIa-tfing barrier, means adapting said rotary trigger to house said mercury button whiie permitting portions et' the peripheralwall'; of saidf mercury button shells; tobe exposed, means rotatably supporting said rotary trigger in said housing', said trigger suppprting means: including" bushing-like projections on. each end' of said trigger* and comapl'em'entary bearing surfaces: in saidy housing for engaging said; trigger projections, stopmeans positiened on said trigger tof be engageable with predetermined shoulders in. said housihgxior limiti-ng therotati'on of said. .rotary trigger with respect: to said housing, elongated strip spring-toontaet meansfor engaging the. peripheral. surface of said buttons, means securing oneA end of said spring Contact means. in said'. housing', abutment meansA supporting the opposite end of caen of said spring contact means, a bow in the center of each of saidspring contact means: for engaging the peripheral surfaces. of said mercury contact buttons and a back cover for said housing to hold the parts in assembled relationships and said cover when assembled being positioned to press against said one end of eachspring.v contact means for causing the latter to exert spring pressure against the button surfaces.

2. A three-way mercury switch comprising a housing made of insulating material, a rotary trigger made of insulating material, a pair of mercury buttons, said trigger having means for supporting said mercury buttons in juxtaposition, each of said buttons having a pair of cupshaped shells forming switch terminals, separate spring contact strips for engaging the outer shells of each of said buttons, spring contact strips for engaging adjacent shells of said buttons, terminal means positioned at one end of each of said strips for connecting the same in an electrical circuit, said trigger having bushings extending axially from each end, said housing having bearing-like supports for engaging said trigger bushings, cooperating stop means on said trigger and housing for limiting the rotation of said ro-V tary trigger in said housing, said spring contact strips each having a bowed portion centrally thereof shaped to engage the peripheral surfaces of said mercury buttons, means securing one end of said contact strips to said housing, a backing plate made of insulating material for closing said housing and for holding said switch elements in assembled relationship and said cover when assembled being positioned to press against the free end of each of said contact strips for causing the latter to exert spring pressure against the button surfaces.

3. A mercury button switch comprising a hollow insulating casing having a front opening and an open back, a hollow trigger element journaled for limited rotation in said casing and having a portion accessible through said front opening, a mercury button switch element disposed within said trigger element for rotation therewith and having a pair of contact shells with cylindrical surfaces separated by an apertured insulating barrier, an elongated spring contact strip having an intermediate portion adapted to engage a peripheral contact surface of said switch element, means securing one end of said strip to said casing, an abutment in said casing adapted to support the free end of said strip, and a back cover for said housing adapted to press the` free end of said strip against said abutment and thereby to urge said intermediate portion into pressure contact with said switch element surface.

4. A mercury button switch comprising a hollow insulating casing having a front opening and an open back, a hollow trigger element journaled for limited rotation in said casing and having a portion accessible through said front opening, a pair of mercury button switch elements disposed side by side within said trigger element for rotation therewith and each having a pair of Contact shells with cylindrical surfaces separated by an apertured insulating barrier, a plurality of elongated spring contact strips having intermediate portions adapted to engage the peripheral contact surfaces of said switch elements, means securing one end of each of said strips to said casing,V abutments in said casing adapted to support the free ends of said strips and a back cover for said housing adapted to press the free ends of said strips against said abutments and thereby to urge said intermediate portions into pressure contact with said switch element surfaces.

5; A mercury button switch comprising a hollow insulating casing having a front opening and an open back, a hollow trigger, element journaled for limited rotation in said casing and having a portion accessible through said `iront wall aperture, a mercury button switch element disposed within said trigger element for rotation therewith and having a pair of contact shells with cylindrical surfaces separated by an insulating barrier, elongated spring contact strips having intermediate bowed portions shaped to conform to the peripheral contact surfaces of said switch element, means securing one end of each of said strips to said casing, abutments in said casing adapted to support the free ends of said strips, and a back cover for said housing adapted to press the free ends of said strips against said abutments and thereby to urge said bowed portions into pressure contact with said switch element surfaces. v

EDWARD R. COUTANT.

References cited in the fue of this patent' UNITED STATES PATENTS Number Name Date 2,142,153 Sambleson Jan. 3, 1939 2,434,065 Courtney Jan. 6, 1948 2,575,318 Mattern Nov. 13, 1951 2,578,494 Wiggins Dec. 11, 1951

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