US2606256A - Mercury switch - Google Patents

Description

Aug- 5, -1952 N. slssENwlNE ETAL L 2,606,255

MERCURY SWITCH Filed oct. 5, 1949 L Qfm/ A @51j IN VEN TORJ /VORMAN Nr.rENwM/e .JACK FAn-KIN Arrom Patented ug. 5, 1952 2,606,256 MERCURY SWITCH Norman. Sissenwine, Takoma" Park; and JackV Ratzkin, Greenbelt, Md.

Application ootobor 5, 1949', soriai'Nofiisv'iz- (Grantedundor the aot of March- 3, 1883, as amonaoa April so, 192e; 370 o, G; 757) Claims.

The invention described herein, if patented, may be manufactured and used by or for the Government for governmental purposes, without the payment to us of any royalty thereon.

This application is a continuation-in-part of our copending application Serial No. 78,264-, led February 24, 1949, now abandoned, for a Mercury Switch. n

This invention relates toY mercury switches; and while illustrated in connection with a multipleI cam and primary circuit, such as commonly used in' ignition systems of internal combustion engines, is capable of general use. Y

An object of the invention resides intheprovision of al switch which will eliminate the possibility of pitting and corrosion such asv cause freduent replacement when tungsten breaker points areA used.

nother object of' the invention" consists in providing a swito'hsu'ohthat the tim-fhg is autornatically maintainedl and changes inv temperature have no deleterious'- effects.

A furtherV object of the invention resides in the provision of a switch in which the contactsl are inclosed and so arranged asto eliminate the possibility of arcing.

Another object of thev invention consists in providing a switch in which ther make or break is` caused by contacting.YY orseparating two charges of mercury.

A still further object of thel invention consists in providing an improved ignition system' for internal combustion enginea Other objects and advantages' of theh invention will beI apparent from the following description when taken in connection with the' accompanying. drawings, in which', o

.Figure 1 is a perspective view of the switch associatedr with a multiple operating cam.v

Figure 2 is a longitudinal sectional view through the switch.

Figure 3f is a transverse sectional View taken ort line 3^3 of Figure 2'; and

Figure' 4- is a vertical sectional view through a slightly modied construction of a switchin closedv position'.

Figure 5 is asimilar view showing a stillfurther modi'ed-form of switch;Y and- Figure 6 is a planview of one of-` the switches placedinanl otherw-isef conventional ignition lcir- Cuit? Referring toA the d"rawin'gsj`- in greater' detail, and particularly to Figures Ito 3`i1'i'c1usiv'e, the numeral l indicates a block ofy insulating'-iaterial, preferably formed' of glass or' sifil'ar I narteri'al' which Wlht bet Wtted by -iu1-..= .T3 block otmate'rial forms `the body of thesw bore 2, with whichv c'rnr'nunicates atran'sver extending annularl recess`- or pocket 3, mo clearly shown Figure 3 wher-ein one portiony of the pocket is shbwn asei'tendingf to av point adjacent the upper wall of the" body meiiib and providedwith a' filling opening 4.; p

Stlidably mounted 4with the borfe; 2V isv a pllii'figfr,` 5 formed of fiberor other insulating material and having a metal conductor 6 embedded' there'- in and extending axially thereof. The,fdiicitor E has Welded theretoV ord integrally' formed therewith intermediate" its' ends, a metal'. dis'o 1 having ,al diameter corresponding to' the dialne-` tor of thenher 4member 5', and hei''g expd at! thevvperiphery" thereof. Thel nietal c'dctrrli extends beyond the end of the plunger 5', as in"- dicated by the numeral 8, and is surroundedby one end' vof a coilv yspring 9,- which" engages" the plunger Eat'on'e' end and: is" seated upon tleina ner faceV of a bracket l0' at its otherA end.. 'Iflfs` bracket is of general U`1s`hape c'nstfru' fon and' is provided with outwardly-turned' flanges 'U means of which itrmayho secured toith' Body stationary portion l ofthe switch; The. to; is also prin/iden1 with a flange |2 which) bensoldered or otherwise electrically' conneV with one'terminal l3', ofthe primary' circuit in which; the switch-is mounted- AA oat Whisker connectedtotheiend` of conductor 6, and t bracket Ill,` Aservesf to' insure; a? ii'ow;y of elj t'zurrent-l through the circuit` when the; switi':l closed,

Disposed Within`- the annular pocket 3i ihthoy hodymomher l, tsja charge-of mrourymi andthe filling opening 4, through vvl'iicli' the` pocket is? rohag'edl with mercury may' he 'closed by aV Yscrew l5,y which also" frs an; ancho" forr the othertermi"nall It'1 of the-Yprinaryci iti An air space Il,vr is provided above tle surface of the mercury for expansionprb"`s,i annif/a'A vent l'is'also provided.. This chargent-me Fury ofcourse,l as clearly shown in-Figuresi 2l anif 3T; forms anV electrical connection betweerfterminal ItV and the disk 1, when thelatter isinvtlie'po sition indicated in these figures. The current will then flow through rod 6, cat whisker III', and bracket I to the other terminal I3, of the primary circuit. It will be noted that when the disk or contact 1, is moved to the right (Figure 2), against the pressure of spring 9, beyond the charge of mercury I4, the circuit will be broken.

The mercury switch shown in Figure 4 is substantially the same as that described above, except that the metal conductor I9 which corresponds to the conductorV 6 of the previously described form is provided with a metal disk 20, which is of lesser diameter than the disk lI, of Figures 1 to 3 inclusive, and is therefore of less diameter than the plunger 5. Consequently, in this modified construction, an annular pocket 2I is formed in the plunger and this pocket is filled with mercury, as clearly indicated in these two figures. This construction of switch has all of the advantages of that shown in Figures l to 3, but has the additional advantage that it presents less resistance due to the molecular cohesion of the two bodies of mercury. Also, there is no wear on the contacting elements, and there is no coeiiicientv of thermal expansion to be contended with in a construction wherein the contacts are formed of two bodies of mercury.

The mercury switch shown in Figure is substantially identical with that shown in Figure 4,

except that in lieu of the metal conductor I9, a

tubular cavity I9 is provided in the plunger 5, and has extending therefrom a plurality of radial passages I9" communicating with the annular channel 2l. The tubular cavity, radial passages and annular channel are lled with mercury, and the mercury in the annular channel serves as a contact in cooperating with the mercury in the annular pocket 3. After the mercury is placed in the cavity I9 etc., the same may be sealed by a screw plug cat Whisker I0' serves to conduct the current from the plug 20 to the bracket I0.

With this particular construction of switch in which the column of mercury is substituted for the solid metal conductor I9danger of injury tothe plug 5, by reason of unequal expansion of the parts due to temperature changes, is eliminated.

The mercury switches as described above, and as `heretofore indicated, are mounted in primary circuits generally indicated by the numeral 22, and provided with a storage battery 23, condenser 24, and an induction coil 25, which latter is associated with a secondary circuit 26 in which the distributor and spark plugs of an internal combustion engine may be connected. The plunger i, is intermittently reciprocated to open and closed position by a rotatably mounted multiple cam 21, provided with 6 lobes in the present instance for use in a 6-cylinder internal combustion engine, the plunger being held in operative contact with the cam by means of the spring 9. In this connection, it is to be noted thatA when the plunger 5 is in engagement with the dwell portions of the rotary cam Z'I, the contact disk I or mercury 2I is in contact with the mercury charge I4, and when the high portions or lobes ofthe cam engage the plunger, the latter is moved to the right (Figure 2) so as to break the primary circuit and induce a high potential in the secondary circuit 26. Y

This particular construction of an annular contact such as the metal disk 1, cooperating with the annularly arranged charge Vof mercury, or a plurality of mercury contacts, has many advan- The tages, not only in an ignition device such as illustrated herein, but also in electrical switches generally. Changes in temperature will have no effect on the operation of the switch because the charge of mercury fills the contact space at all times; also the contacts are entirely inclosed and thus eliminate arcing. Moreover, accurate timing is automatically maintained at all times because the switch is caused to open at the exact instant that the left hand edge of the disk I or the mercury rings 2| or 2| leave the right hand edge of the annular charge 3 of mercury. Furthermore, by means of lthis arrangement the use of breaker points and the resultant pitting, disarrangement of timing, and replacement of the points, are avoided. Additionally, the switches shown in Figures 4 and 5, by reason of the contact being formed of two charges of mercury. will provide lessened resistance for the reason mentioned above, and will obviate any possibility of wear on the contacts, since the mercury charges are automatically maintained at full capacity. Also there can be no possibility of binding between the movable parts, inasmuch as the contacting elements are formed of pockets of liquid metal.

The term mercury employed herein and in the claims to designate the liquid conductor is to be construed as including any electrical conductor which is liquid at normal temperatures.

In accordance with the patent statutes, We have described what we now deem to be the preferred form of construction, but since various minor changes may be made in structural details without departing from the spirit of the invention, it is intended that all such variations be included within the scope of the appended claims.

We claim:

1. In a mercury switch a. stationary portion, a reciprocable portion associated therewith, one of said portions provided with an annular mercury-receiving pocket, an annular metal contact connected with the other portion for contacting the mercury in said pocket, and electrical conductors connected with said pocket and said annular contact respectively.

2. A mercury switch comprising a stationary portion of insulating material provided with a bore opening into an annular mercury-receiving pocket, av plunger formed of insulating material reciprocably mounted in the bore, said plunger provided with a longitudinal mercury-receiving cavity and an external annular groove communicating therewith.

3. A mercury switch comprising a stationary portion of insulating material provided with a bore opening into an annular mercury-receiving pocket, a plunger formed of insulating material reciprocably mounted in the bore, said plunger provided with a longitudinal mercury-receiving cavity, and an external annular groove communicating therewith, and electrical conductors associated with said pocket and said cavity.

4. A mercury switch comprising a stationary portion of insulating material provided with a bore opening into an annular mercury-receiving pocket, said stationary portion provided with an air space and a venting passage connecting said pocket with the atmosphere, a plunger formed of insulating material reciprocably mounted in the bore, and an annular contact carried by the plunger for coacti'on with the mercury in said pocket, and a conductor disposed axially of the plunger vand connected with said annular contact.

5. A mercury switch comprising a stationary 5 portion of insulating material provided with a bore opening into an annular mercury-receiving pocket, a plunger formed of insulating material reciprocably mounted in the bore, an annular contact on said plunger for coaction with the 5 mercury in said pocket, and a conductor mounted axially of the plunger and connected to said annular contact.

NORMAN SISSENWIN E. JACK RATZKIN.

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

6 UNITED STATES PA'IENTS Number Name Date Harper Nov. 26, 1895 Hutton Apr. 7, 1903 McLean Dec. 29,l 1903 Freese June 7, 1904 Crist et al. Oct. 8, 1912 Sigman Dec. 4, 1934 Paris Feb. 10, 1948

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