Sept. 10, 1946. E. G. MILLER ETAL 2,407,378 SWITCH Filed March 14, 1944 QM. \ mm\ ,ä f INÉNTORS W ¿I B TQRNEY Patented Sept. 10,» 194€ 2,407,378 UNITED STATES PATENT OFFICE 2,407,378 SWITCH Edward G. Miller and Ralph E. Engberg, New York, N. Y., assignors, by mesne assignments, to Allied Control Company, Inc., New York, N. Y., a corporation of New York Application March 14, -1944, Serial No. 5426,37’7 2 Claims. (Cl. 200-144) 1 2 This invention relates to switches and more especially to switches for use in electrical ap Fig. 2 is a view similar to Fig. l with the switch in closed condition, and Fig. 3 is a section on the line 3-3 of Fig. l. A box-like casing iû of insulating material is provided with a removable cover Ii attached to the casing by fasteners i2. In the bottom of the casing lil are two apertures I3 through each of which extends a threaded binding post Id having a head i5 co-nstituting a Contact. The binding post ifi is hermetically sealed in a glass bead i5 which in turn is hermetically sealed in the bore of a metal bush il'. The assembly just pliances for airplanes. As is well known, the pressure within an air plane varies to a considerable extent dependent upon the elevation at which the plane is flown. At certain pressures below normal surface level atmospheric pressure, sparking between contacts is materially increased. Thus, a switch which operates without appreciable sparking between its contacts at ground level will be characterized by considerable sparking between the contacts at elevations normally attained by airplanes. An object of this invention is a switch hav ing provision for satisfactorily suppressing arc ing between the contacts when the switch is carried by an airplane to high elevations. described is a commercial product obtainable on the open market. A metal member iîl has an aperture through which the binding post extends and a nut i9 threaded onto the end of the bolt iii holds the binding post with the bush il engaging the inner A further object of this invention is a switch surface oi the casing bottom and the member i3 which may safety be used in an atmosphere con taining explosive vapors or gases. 20 engaging the outer surface of the casing bot tom. A Sylphon bellows Eil of either metallic or A still further object of this invention is a non-metallic flexible material has one end her mounting for two relatively movable contacts oi' metically sealed to the bush il and its other end such nature that the atmosphere surrounding hermetically sealed to a metal plate 2l support the contacts is maintained of the same composi tion and at substantially uniform pressure. 25 ing a Contact 22. The flexible wall chamber thus formed may contain an arc suppressing atmos In one type of switch embodying the inven phere or may be evacuated to a degree sufñcient tion, a pair of relatively movable contacts are satisfactorily to suppress arcing. arranged within an air-tight ilexible wall cham A metal bridge member 23 contacts each of ber and a suitable gas, for example, air, nitro gen, etc., is provided within the container at pres 30 the plates 2| and is provided with a central depression 24 between which and the bottom of sure which will satisfactorily suppress arcing be the casing is arranged a spring 25. A pin 2S tween the contacts. Means are provided for ef is slidably mounted in a frame 2l with one end fecting relative movementI of the contacts toward engaging the portion 24 of the bridge 23 and with and away from each other. The chamber is so mounted in the switch that at atmospheric pres- ` the other end enlarged to form a head 28 en gageable with the frame 2l to limit downward sure it is under slight compression tending to movement of the pin. A leaf spring 29 is carried by a bracket 3b attached to the wall of the casing in by a screw 3| and engages the head 28. A cradle 32 is pivotally supported by a shaft sure of the atmosphere surrounding the contacts . 33 journalled in the legs of a U-shaped member remains substantially constant. Each chamber 42 supported by the side walls of the housing may contain an arc inhibiting vapor, thereby li] and having its bight portion extending be minimizing arcing. Such a switch may also be tween the lower surface of the frame 2ï and the used in an atmosphere containing explosive gases or vapors a5 any arcing which may develop be 4.5 upper surface of the depression 24 in the bridge member 25, there being an aperture in said bight tween the contacts will be wholly retained within portion for the pin 25 to project through. The the chamber. relationship of the U member bight to the bellows Other objects, novel features and advantages members 2i) is such that when the bellows mem of this invention will become apparent from the maintain the maximum gap permissible between the two contacts. Thus, irrespective of the ele vation to which the switch is carried, the pres following specification and accompanying draw ing, wherein: bers are assembled in the switch at surface level atmospheric pressure the bellows 2i! are slightly Fig. 1 is a vertical section through one em compressed. A block of insulating material 34 likewise is pivotally supported by the shaft 33 bodiment of the invention, the switch being in open condition and parts thereof being shown in elevation; and is provided with an operating handle 35 ex 65 tending through an aperture 36 in the cover H. asevera It A plunger 4 extends through an aperture in tacts thereiore remains constant irrespective of the pressure surrounding the casing lil. Spark ing between the contacts is thus satisfactoriiy suppressed irrespective of the elevation at which the switch may be operated, Also, the switch the cradle 32 and is provided with a head 33 pivoted to the block ¿ill in a recess Z'lil provided in the block by means of a pin All. A spring 4l surrounds the plunger' Eil with one end abutting the head 3B and the other end abutting the end wall oi" the cradle. The cradle Si and the parts may be made use of in an atmosphere containing explosive mixture as any sparks that may be gen associated therewith directly overlie the spring 2S. erated upon opening- of the contacts are retained within the chamber, In Fig. 1, the parts are shown with the switch in its open condition. The spring .'¿ál rests against We claim: 1. A switch comprising a contact bridging mern~ the head 2d and the pin 2d together with the bridge ZS and contacts are held in elevated position by the spring and the expansive for-ee of the bellows Clockwise rotation of the block 3a by operation or” the handle lifts the pivot pin ¿lil to reverse the position of the plunger ‘il rela» tive to horizontal with the result that the cradle 32 is rocked countercloclrwise from the posi' ion The downwardly shown leftinend Fig.to or“l apply the to the spring pressure position is to thereupon shown the bead in iii . of the pin 2:5 thereby forcing the bridge and con» tacts downwardly against the action oit the spring 25 into engagement with the contacts it“ to close a circuit between the two binding posts lil. The switch remains closed so long as handlA Elli is lett its lï‘ig. 2 position.. counterclocirwise movement of he - _ , Upon the switch returns to the position In the event that the flexible che`I tains an arc»suppressing atmosphe pressure er higher or an inert g pheric example, pressure as nitrogen or higher. underAs substant an alte rnative, tho flexible chamber be ed to auch degree that ionizing thepoten residual Zal greater gas inthan the the chamber potential hasto be satisfactorily applied between suppressed the contacts under oroperating that arcing condim tions for which the device is designed. The con dition of the atmosphere surrounding the oon ber arranged for rectilinear movement, a stop, resilient means biasing said bridging member toe ward said stop7 a pivotally supported hollow .3) rocker, a reoiprocable pin havin-g one end en gaging bridging member, a leaf spring ñxed at one end and extending across the remaining end of said pin in position to be engaged by said rocker, an oscillating member within said rocker 20 coaxial therewith7 a stud pivoted at one end to oscillatable member and extending through f aperture in said rocker, a shoulder on said stud and a resilient member interposed between said shoulder rocker, pin being eiîective upon operation of :aid oscillatable member to move said bridgiîg me er away from said Stop. A switch according to claim l characterized by a pair oi' air»tight chambers each compris two rigid metal end members interconnected by a metal bellows member, means supporting said c* nibers with one end member of each chamber ai and the other end member capable ci :nove rnent toward and away from fixed end mein»n ber and arranged for engagement by said bridg ing member, a contact supported by each member ci" a chamber within said chamber with one Contact of each chamber insulated from its sup« porting member, and a conductor leading through each stationary end member to the Contact sup ported thereby. ED'WARD G. MILLER. RALPH E. ENGBERG.