US2906841A - Three-phase vacuum switch - Google Patents

Description

Sept. 29, 1959 J. E. JENNINGS THREE-PHASE VACUUM SWITCH 2 Sheets-$heet 1 Filed Jan. s, 1956 3n n I 755255074 r. I m

I /N VE N TOF? L/O EMMETT JENNINGS 16/1, AT TOPNE Y Sept. 29, 1959 J. E. JENNINGS mass-mm VACUUM swI'rcH 2 Sheets-Sheet 2 Filed Jan. 3, 1956 bis ATTORNEY United States Patent THREE-PHASE VACUUM SWITCH Jo Emmett Jennings, San Jose, Calif., assignor to Jennings Radio Manufacturing Corporation, San Jose, Calif., a corporation of California Application January 3, 1956, Serial No. 556,943

9 Claims. (Cl. 200-144) My invention relates to vacuum switches having multiple contacts enclosed within a vacuumized envelope and adaptable for separate or simultaneous operation.

One of the objects of my invention is the provision of a 3-phase switch in which the three pairs of contact points are arranged within a single vacuumized chamber.

Another object is the provision of a multiple contact vacuum switch of such rugged construction as to be highly resistant to physical injury from external forces.

Another object is the provision of a multiple contact vacuum switch in which each fixed contact rod is concentrically supported in a ceramic tube which constitutes part of the switch housing and also a shield for the deposit and controlled dispersal of vaporized metal emanating from the contacts.

Another object of my invention is the provision of a vacuum switch structure in which the degassing temperature may be substantially raised with corresponding benefits in improvement of the vacuum.

Another object of my invention is the provision in a vacuum switch of an improved housing structure and shield for the contact rods.

Still another object of the invention is the provision of a vacuum switch in which the ratio of contact area to the inside area of the envelope is very small so that a long operating life is assured.

Other objects of the invention together with the foregoing will be set forth in the following description of my invention. I do not limit myself to the showing made by the said description as I may adopt variant embodiments of my invention within the scope ofthe appended claims.

Referring to the drawings:

Fig. 1 is a vertical sectional view of a 3-phase vacuum switch embodying my invention. The plane of section is indicated by the line 1-1 of Fig. 2.

Fig. 2 is an end view of my switch taken from the position indicated by the numeral 2 in Fig. 1.

Fig. 3 is a fragmentary view of the left hand end of a switch such as shown in Fig. 1, but with a dielectric connection between the movable contacts to enable their simultaneous operation.

In broad terms my vacuum switch comprises a generally cylindrical steel housing designed to withstand the high pressure of substantially complete evacuation; and having a plurality of pairs of aligned and oppositely disposed ceramic tubes extending from inside the main housing through its circular ends. Each tube terminates in a hermetically closed or sealed end cap; and each is also fixedly mounted in and hermetically sealed to the circular housing wall through which it extends. Within the main housing, the aligned ends of each pair of tubes are spaced apart, the gap being nearer to one end of the main housing than to the other. In each pair of aligned housing tubes, a mated pair of fixed and movable contact rods are concentrically supported on the end caps of the housing tubes; and operating means is provided to close and open a circuit through each mated pair at a point spaced equally from the main housing end walls and to one side of the gap between the aligned tubes, so that one of the tubes of each pair forms a cylindrical shield about the contact points. The gap permits dispersal of vaporized metal from the contact points into the large chamber within the main housing.

In the operation of my switch metal is vaporized at the contact points. The metallic deposit from this vapor Within the tubular shield is mainly adjacent its open end and is negligible adjacent its capped end. Vapor emerging from the open end of the shield is directed by a battle against the metallic wall of the main housing and any deposit thereon is innocuous. There is therefore no build-up of a metallic conducting film within the vacuumized chamber of my switch, and which could cause shorting and failure.

In the embodiment of my invention shown herein, three pairs of aligned contact rods are shown. One rod of each pair is fixed within the envelope or housing and the pairs are spaced apart. Means are provided for movably mounting one of the contact rods of each pair; and these movable contact rods may be connected if desired for simultaneous operation to close or open all circuits through my switch at the same time.

This mounting of a plurality of switches within a single vacuumized housing effects an important saving in space and weight over separate mounting of the switches, besides giving a more rugged structure at lower costs. It also simplifies assembly and speeds the labor of making connections.

By the use of stainless steel in the housing and the elimination of glass, the bake-out temperature can be considerably increased, perhaps as much as 400 to 500 F. Since degassing of metals is a function of time and temperature, I am able to achieve a higher degree of degassing and cleaner internal parts by using a temperature of about 1250 F.

My multiple pole switch design increases the amount of evacuated area to several times the area found in an evacuated single pole switch, thus materially increasing the life expectancy of the implement. The ratio of con tact area of the contactpoints to the inside area of the envelope subject to deposit of metal is'very small.

Where safety is a paramount factor in the switching of heavy currents, my design lends itself readily to connections with lead shielded high potential conductors by means of the conventional wiped joint connections and insulation.

In greater detail and with specific reference to the embodiment in the drawings, my switch comprises a cylindrical metallic main housing formed of two like parts 2 and 3, in the opposite circular ends 4 and 5 of which, are seal-mounted three pairs of aligned or mated dielectric tubes 7 and 8, preferably ceramic. The two conductive cup-shaped main housing parts are identical and are welded at their rims to the annular mounting flange 9, by which the switch is mounted in its supporting panel. The housing is preferably stainless steel or nickel and ribs 11 are formed in the ends to provide stiffening against atmospheric pressure which follows vacuumization of the housing achieved through tubulation 12.

The tubes 7 and 8 are aligned in pairs spaced equally around each end of the housing; and are seal-mounted in the housing ends over openings therein, by vacuum tight seals, comprising in each case a copper or nickel metal annulus 13 of C-shaped radial section, integrally united, as by brazing, on one rim 14 to the metallized annular bead 15 formed integrally on the ceramic tube, and on the other rim 16 integrally united to the adjacent surface of the housing end. This union permits small relative changes between the parts due to their different coeflicients of expansion. Thus each ceramic tube exsh sthm sh and issealed n the end Wall o th in housing, and terminates within the housing, but with a gap 17 between the inner ends of each mated pair. .91 c he tub s .8 xtends. .tuuher int the ma n h ushs than s al n d. matei'l, and theretqre lon e o. th the. p betweeuthe nne ends f. the al gned tub s li Wel to. ne de of the entral p he be ween he ho s n nd i The outer end of each tube is closed hermetically y a. co e c s r p te or n c p 1.8. s a ed. to. t e tube by the copper or nickel annulus 12. The free end QE- e ch r mic tube .7 is: closed hermetica y y a rne cl s plat r end. can 21, sealed. to. the tube by t e annul sethat each ceramic tube pr v d a; dielectric extension of the conductive main housing,

the vacuumized chambercxtending throughout the whole ho sing including. thejtubes.' It will be. noted that in addition to the inherent mechanical rigidity imparted. to the structure by the integral union of the seal. 13, evacuation of the. housing. and tubes. gives additionalv rigidity to the, mounting of. the. tubes. Reductio'n of pressure within the housing results in the. tubes being. pressed inwardly by atmospheric, pressure. This considerable inward pressure is carried, by the annular. bead 15. tightly abutting the inherently strong. and. rigid ends 4. and. 5 of the main housing. .The seals 13 are thus not subjected to undue mechanical stresses, and long. life is. assured.

Conductors terminating in. tungsten contact points meeting midway between the housing, ends, are. mounted on the closure plates of each tube. On. one side (right of Fig. l) the points 26 are fixed. On. theopposite side FhQLPQ l 2.7-.a em v b1e- Contact points 26, of tungsten, are secured in. heavy copper contact, rods 28, integrally united asby brazing with and rigidly supported, on the closure plate. 18. On the outside face of. the, closure platethe rod extends as studZQ to provide a connecting lead.

, Tungsten contact points 27 are fixed in heavy copper rods 31 brazedto theend 33.0f-thecopper. bellows,34, the further end of which is brazed. to the. closure. plate 21 and t the long. bearing tube. 36, integrally connected to the closure plate. The assembly. of. contact. rod, bellows, bearing. tube, closure plate and ceramic tube is concentric about thelongaxis of.- the ceramic tube 7, and in axialv alignment. with the matedfconcentric assemblyoflpai ts. on the. opposite end. of the main hous- 1 21 a Means, are provided. for. moving. the. mobile contact point, .7.. into. andout. oiengagement with the fixed 'contact point 26 ,to close or open the. circuit controlled by these contacts. Brazed to the inside of the bellows end and slidablyfittingin the bearing .tube isthe steeLactuath aft}? by. which the.mobilecontactpointlT may be pulledaway from thefixed contact. point 26.to open the circuit, or allowed. t o engageftherewith to close. the circuit. Itwill bellnder stood oicoursethatsince the chamber within thehousing and, ceramic extensions thereof is vacuurnized, atmospheric pressurewithin the bellows, maintained through the bearing bore in the. bearing tube 36, tends to keep the contact pointsf26. and.27.engaged. An llitable operator, such .as one actuatedlby a solenoid 01g zfnrrnay be connected to the threadedend38of the s a t.

It is desirableto protectthe relatively. delicate bellows from the high velocity, metallic particles projectedby F 1 1, Z9; n tefore mount a metallicshield plate 91 mob le rod 32 near its free end. The shield platenray beflat or dishedand extends past the adjacent flm he fl'hmic. tubes. sothatdirectaccess to the bellows is blocked. A flat or slightlydishedshield platetends to a direct 'a substantial, portion of the. vaporized metal produced by the arctowarda selectedarea on hawed: .Q 1ain ,housingcylindrical :wall; and thus to a sensible deggee, concentrate the depQS t i thi harmless area.

It .will be understood that my switch in the embodiment illustrated in Fig. 1 includes three pairs of aligned contacts and associated devices, each pair identical to the pair just described; and each pair independently operable to control the circuit therethrough. Means are provided however fo Operating all three pairs together if simultaneous control 'of the circuits is desired.

Referring to Fig. 3, each of the actuating shafts 37 is rigidly fixed in a dielectric disc 42 by nut 43 on one side and connecting lead or stud {$4 on the other. The disk is suitably beaded. and ribbedas shown for stiliness; and is provided at its center with a threaded stud 46 by which the disc may be connected to a suitable operator for simultaneous control of all three circuits.

Iclaim: l. A vacuum switch comprising a vacuumized conductive housing, a pair of aligned dielectric tubes disposed on opposite endsot the housing. and hermetically sealed thereto, a closure plate hermetically. closing. the

free end/of one of said tubes, a contact rod. rigidly fixed on said closure plate and extending concentrically through the tube into. the housing, a second. closure plate hermetically closing the free end: ofthe second'tube and including a slide bearing. concentric with the tube, a bellows enclosing. the inner end of the. bearing and hermetically. sealed to the second closure plate, an actuating. shaft slidably extending through the bearing and rigidly fixed. at its inner endlto. the. bellows, and a second contact rod rigidly fixed on the end. of the bellows and extending. concentrically through said second tube into the housing.

2. A vacuum switch as specified in claim 1 in which a shield plate is disposed on the second contact rod between. itscontact end and the edge of theassociated dielectric tube.

3. A vacuum switch as specified in claim 1' in which the vacuumized conductive housing is a hollow steel cylinder closedbyparallel end plates, and three said pairs of aligned dielectric tube assemblies are evenly spaced circuinferentially on the housing ends.

4. A vacuum switch as specified in claim '1' in which the conductive housing comprises a pair of like cylindrical steel cups integrally united attheir'rims to a common 'steel 'annulus constituting a mounting flange.

5. A- vacuum switchas specified'in claim 1 in Which the proportions of the parts are such that the contact 'points lie substantially equidistant from the ends of the housing;

6. A vacuum switch as specified in claim 1 in which the end of each dielectric tube opposite its free end extends into the housing.

7. A vacuum switch as specifiedinclaim 1 in which each dielectric tube is provided with an annular bead abutting the adjacent housing end, and; the tube beyond the bead exten'ds into the housing. l

8. A vacuum'swi-tch as specified in claim 3 in which a dielectric disk rigidly connects the three slidable shafts for simultaneous operation of the three movable contacts.

9. A vacuum switch comprising a vacuumized conductive housing, apair of-aligneddielectric tubes disposed on opposite ends ofthe housing-andhermetically sealed thereto, a'closure plate hermetically closing the free end of one ofsaid'tubes, a contact rod'rigidly fixed on said closure plate and extending concentrically through the tube into the housing, a second closure plate hermetically closing the free end of the second tube andincluding a slide bearing concentric with the tube, a bellows; enclosing the inner end of thebearing and herrnetically sealed to the secondclosure plate, an actuating shaft slidably extending through the bearing and rigidly fixedat its inner end to the bellows, and a second contact rodrigidly fixed'on the end of the bellows and extending concentrically through said second tube into the housing, at least one of said dielectric tubes extending into References Cited in the file of this patent UNITED STATES PATENTS Rankin May 16, 1939 Millikan et a1. Dec. 9, 1930 Prince July 14, 1931 Kopeliowitsch Nov. 1 4, 1933 6 Sorensen Sept. 4, 1934 Perrymen et al. Nov. 28, 1939 Schwennesen June 15, 1948 Atkinson June 26, 1951 Jennings Apr. 3, 1956 FOREIGN PATENTS Germany Mar. 3, 1941 France Nov. 17, 1941

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