US3222484A - Expansible vacuum envelope for electrical devices - Google Patents

Description

Dec. 7, 1965 J. E. JENNINGS EXPANSIBLE VACUUM ENVELOPE FOR ELECTRICAL DEVICES Filed June 1. 1961 m M WW5 mJ mg .JM mm United States Patent 3,222,484 EXPANSIBLE' VACUUM ENVELOPE FOR ELECTRICAL DEVICES Jo Emmett Jennings, SanJose, Calif., assignor, by mesne assignments, to Jennings Radio Manufacturing Corporation, San Jose, Calif., a corporation of Delaware Filed June 1, 1961, Ser. No. 114,098 8 Claims. (Cl. 200"1-44) This invention relates to electrical devices such as vacuum switches and vacuum capacitors for example, and the principal object of the invention is the provision in devices of these types of a lightweight vacuum envelope which is more easily manufactured that vacuum envelopes heretofore known.

Another object of the invention is to provide lightweight single pole vacuum-switches, several of which may be actuated by one armature to provide a multiple pole switch.

Still another object of the invention is to provide a vacuum switch of simple construction resulting in reduced frictional losses and-increased switch life.

A still further object of the invention. is the provision of an expansible envelope constructionfor vacuum devices such as switches and capacitors incorporating relatively movable electrodes so that expanson and contraction of the envelope effects relative movement of the electrodes.

Other objects and advantages of the invention will become apparent from the following description in which:

FIG. 1 is a side elevational view of a preferred form of the invention embodying a vacuum switch the envelope being partly broken away to show internal structure;

FIG. 2 is a fragmentary cross sectional view of the sidewall of a modified form of the envelope of FIG. 1; and

FIG. 3 is a fragmentary cross sectional view of the sidewall of still another modified form of the envelope of FIG. 1.

For clarity and facility of illustration and description, the invention is hereinafter described as embodied in a novel vacuum switch. It is to be understood, however, that the invention is not limited to the showing made by the said description and the drawing, since it may be embodied in variant forms within the scope of the appended claims.

In common with earlier types of vacuum switches, the vacuum switch embodying this invention includes a fixed contact and a mobile contact 11 (FIG. 1), and terminals 12, 13 respectivelyconnected for conducting electricity to said contacts. However, the evacuated envelope of this invention differs from the evacuated envelopes of earlier types of vacuum devices including vacuum switches in that it is expansible rather than rigid. Envelope 14 expands to allow contact 11 to be moved from a position engaging contact 10 to a position separated from said contact, that is, from the closed position of the switch to its open position. At least one section or portion of envelope 14 is formed from nonconducting material to insulate terminals 12, 13 from each other when contacts 10, 11 are not engaged. The following description of a form of this invention should not be deemed to restrict this invention to the particular form described.

In the preferred form of the invention shown in FIG. 1 an evacuated envelope is formed by a pair of opposed ends 16, 17 connected together by cylindrical sidewalls 14. The end 17 of envelope 14 is preferably of metal and is provided with the contact 11 which may conveniently be considered to be the mobile contact. Said mobile contact 11 may be brazed or otherwise fixedly secured to the inner side of end 17, and terminal 13,

preferably a threaded stud, may be brazed to the outer side of end 17.

The opposite end 16 of the envelope is provided with a central apertured boss 23 through which is received a shaft 25 hermetically sealed to end 16' at boss 23. Said shaft 25- may be threaded at its outer end as at 12 to form a terminal. The inner endof shaft 25' carries the fixed contact 10 which is preferably positioned so that atmospheric pressure acting on the ends 16, 17 causes the contacts 10, 11 to close as seen in FIG. 1. Sidewalls 14 are made expansible in a manner to be described so that ends 16, 17' may be urgedapart to open contacts 10 and 11 against the closing pressure of the atmosphere.

The expansible sidewalls 14' are formed by aplurality of similar cylindrical sections of ceramic material, said sections being indicated at 18. The annular surfaces of theouter sections 18 that connect with ends 16, 17 are metallized so thatsaid sections may be hermetically sealed as by brazing to said ends. In like manner the other an nular surfaces of said outer sections are metallized to permitthe same to be: hermetically brazed to expansible elements or bellows that are interposed between each adjacent pair of ceramic sections.

In FIG; 1 four such expansible elements are shown designated 20 and eachcomprising a pair of opposed annular flanges 21 connected together by an annular juncture 22. The expansible elements or bellows elements 20 may be formed from relatively thin copper sheet by spinning or maybe more conveniently formed by brazing the two opposed flanges together along their common juncture. It will be apparent that the juncture 22 provides a hinge permitting the flanges 21 to move relatively thereby permitting ends 16, 17 to move toward and away from each other to engage and disengage the contacts 10. 11. The more bellows elements that are used the greater will be the yieldability of the switch and the less will be the strains applied to said bellows elements.

In FIG. 1 the juncture 22 that connects the opposed flanges 21 is formed to provide a relatively large radius thereby tending to reduce localized stresses. However the bellows elements may be formed as indicated in FIG. 2 wherein the juncture 32 is formed to a radius no greater than half the nominal distance between the opposed flanges 31. If the amount of deflection to which each bellows element is subjected is not very much greater, the somewhat simpler construction of FIG. 2 may be resorted to.

In order to effect a relatively greater flexibility, additional folds may be formed in the metal sheet from which the bellows element is made. For example, in FIG. 3, there is provided an additional fold of material so that in addition to the pair of opposed flanges 35 that are secured to the adjacent surfaces of the ceramic sections 18 a central fold is formed to provide an additional pair of flanges 36 connected together by juncture 38 and connected to the two secured flanges 35 by junctures 37, 39.

It will be apparent that the particular spacing between contacts 10, 11 may be adjusted by moving contact 10 with shaft 25 before the latter is sealed to end 16 so that when the envelope is evacuated contacts 10, 11 are engaged with the desired amount of force. Such evacuation may be achieved through a tubulation such as indicated at 24 in FIG. 1.

The above described structure is not only simple and rugged but lends itself to relatively fast assembly thus effecting a considerable saving in manpower. Conventional shielding devices may, of course, be carried by the ends 16, 17 to prevent deposit of vaporized metal on the ceramic sections if desired.

The specific description herein given of the preferred forms of the invention should not be taken as restrictive of the invention as it will be apparent that various modifications in design may be resorted to without departing from the scope of the invention as defined in the following claims.

I claim:

1. An hermetically tight hollow envelope comprising a composite sidewall including a plurality of axially spaced tubular ceramic sections and an expansible tubular metallic member interposed between each two adjacent tubular ceramic sections, a metallic bond hermetically interposed between the coaxially aligned ceramic sections and each associated expansible metallic member, and rigid endwalls closing opposite ends of the composite sidewall.

2. The combination according to claim 1, further including electric contact means and terminal means carried by each of said endwalls, whereby relative movement of said endwalls engages and disengages said contacts.

3. The combination according to claim 1, wherein each of said expansible tubular metallic members is comprised of relatively thin metal folded upon itself to provide a pair of opposed flanges, the outer peripheral edge portions of said flanges being bonded to said tubular ceramic sections.

4. The combination according to claim 3, wherein said expansible tubular metallic members are folded to pro vide a plurality of spaced apart folds.

5. A vacuum switch comprising: an expansible evacuated envelope, said envelope being formed by a composite sidewall including a plurality of spaced axially aligned electrically insulating tubular sections and an expansible tubular section interposed between, coaxial with, and hermetically bonded to each two adjacent insulating tubular sections to permit relative axial movement between said insulating tubular sections, and rigid endwalls closing opposite ends of the composite sidewall, each endwall carrying an electric contact whereby relative movement of said endwalls engages and disengages said contacts.

6. The combination according to claim 5, wherein said electrically insulating tubular sections are of a ceramic material and each said expansible tubular section is comprised of relatively thin metal folded upon itself to provide a pair of opposed flanges.

7. The combination according to claim 6, wherein each said expansible tubular section extends radially inwardly from said insulating tubular sections, the outer peripheral edges of said flanges being bonded to said insulating tubular sections.

8. The combination according to claim 7, wherein each endwall further includes terminal means electrically connected to its respective electric contact.

References Cited by the Examiner UNITED STATES PATENTS 1,836,654 12/1931 Dorn et al. 200144 1,905,751 4/1933 Rankin 200144 2,326,074 8/1943 Slepian 200144 FOREIGN PATENTS 638,489 2/ 1928 France.

663,422 8/ 1938 Germany.

245,185 7/ 1947 Switzerland.

BERNARD A. GILHEANY, Primary Examiner.

MAX L. LEVY, ROBERT K. SCHAEFER, Examiners.

Claims (1)

1. 5. A VACUUM SWITCH COMPRISING: AN EXPANSIBLE EVACUATED ENVELOPE, SAID ENVELOPE BEING FORMED BY A COMPOSITE SIDEWALL INCLUDING A PLURALITY OF SPACED AXIALLY ALIGNED ELECTRICALLY INSULATING TUBULAR SECTIONS AND AN EXPANSIBLE TUBULAR SECTION INTERPOSED BETWEEN, COAXIAL WITH, AND HERMETICALLY BONDED TO EACH TWO ADJACENT INSULATING TUBULAR SECTIONS TO PERMIT RELATIVE AXIAL MOVEMENT BETWEEN SAID INSULATING TUBULAR SECTIONS, AND RIGID ENDWALLS CLOSING OPPOSITE ENDS OF THE COMPOSITE SIDEWALL, EACH ENDWALL CARRYING AN ELECTRIC CONTACT WHEREBY RELATIVE MOVEMENT OF SAID ENDWALLS ENGAGES AND DISENGAGES SAID CONTACTS.

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