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Патент USA US3026404

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March 20, 1962
3,026,394
J. E. JENNINGS
VACUUMIZED ELECTRIC SWITCH
Filed Nov. l0, 1959
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3,026,394
Unit@ States
Patented Mar. 20, 1962
2
1
Another object of the invention is the provision in a
3,026,394
switch of the character d-escribed of a detachable non
.
VACUUMIZED ELECTRIC SWEI‘CH
Jo Emmett Jennings, Sau Jose, Calif., assigner, by mesne
assignments, to Jennings Radio Manufacturing Cor
poration, San Jose, Calif., a corporation of Delaware
Filed Nov. 10, 1959, Ser. No. 852,058
6 Claims. (Cl. 20G-_144)
conductive bearing means for the movable electrode.
Other objects will be brought out in the following de
scription of the invention. l do not limit myself to the
showing made by said description and the drawings, since
My invention relates to vacuum switches and especially
to such switches of large diameter and very large capacity.
With reference to the drawing, the FIGURE is a half
sectional view of a switch embodying my invention, The
I may use variant forms of the invention within the scope
of the appended claims.
One of the principal objects of the invention is the pro 10 scale is approximately two-thirds actual size.
In broadly descriptive terms, the switch of my inven
vision of a vacuumized switch having an envelope large
enough to hold the heavyl conductive structure and con
tion and as illustrated in the drawing comprises a large
glass cylindrical shell closed at each end by a heavy cover
plate. Within the shell and cover plate at each end, a
With the development and use of'electric power, there 15 relatively >thin- two-part annular .copper membrane is
joined hermetically to the shell in a conventional metal
has been an increasing demand for larger and larger vac
to-glass seal.
’
'
num switches to handle the increasing current loads.
At the fixed contact end of the switch, the relatively
Expanding the diameter and capacity of vacuum switches
large central aperture of the two-part annular membrane
has been severely hampered by the inherent weakness of
the metal-to-glass or conventional Housekeeper’s seal. 20 is hermetically closed by a pair of concentrically arranged
and integrally united annular plates. The inner plate is
Any increase in size of a vacuumized shell or envelope
detachably secured to the overlying cover plate. A iixed
results in a directly proportional increase in total pressure
electrode extending into the glass shell-through and her
exerted by the atmosphere on all exposed surfaces of the
metically brazed to the inner periphery of the inner plate
envelope; and on an eight inch generally cylindrical evac
completes the seal at this end of the shell. VThus atmos
uated envelope, the pressure tending to crush in each end
pheric pressure on the ñxed contact end of the switch is
amounts `to more than 700 lbs. vThis is greatly in excess
imposed only on the exposed area of the membrane, while
of pressures which can be borne by switches having con
the major pressure as well as the weight of the ñxed con
ventional metal-to-glass unions or seals.
tact and its related concentric plate structure is borne by
In addition to stresses imposed by atmospheric pressure,
the conventional seal >must carry stresses imposed by the 30 the cover plate abutting the end of the glass shell.
At the other end of the shell, which constitutes the
Weight, sometimes considerable, of operative parts
mobile rcontact end of the switch, a similar annular me
mounted on the ends, and also, the impact shock of clos
tallic membrane is arranged in a mctal-to-gl-ass seal with
ing contacts and the outward jerk of the opening contacts.
-A primary object of my invention therefore is to pro 35 the shell. In this case however, the inner rim or" the
annular membrane is integrally united, through the me
.vide means whereby a large vacuumized nonconductive
dium of an annular plate and a collar, with the outer rim
cylindrical shell can be closedl hermetically at its ends,
of a metallic bellows which extends into the envelope
and possess strength amply sufñcient to »carry the heavy
and is hermetically closed 'across its inner end by an
loads imposed by its size.
operator stem. The mobile contact of the switch is fixed
Because of the excellence of the conventional metal-to
on the inner end of the stem within the vacuumized en
glass seal under ideal conditions of light loading, it also
- velope and in axial alignment with the'ñxed contact. The
lis an important object of my invention to utilize the metal
stem extends out of the open end of the bellows, for con
to-glass seal in cooperative relation'with a heavy load
nection to a solenoid or other operator.
bearing structure so that the metal-to-glass joint performs
Atmospheric pressure tends to close the mobile contact
its primary function of hermetic sealing, but is relieved
upon the aligned fixed contact to close the circuit through
of destructive pressures, torsions and other stresses, which
tacts required for carrying currents upto 10,000 amperes
or more.
'
«
tend to cause failure.
-
Because of the high cost of electrical implements of
this character, another object of my invention is the pro
vision of a vacuumized envelope which can readily be 50
opened for replacement or repair, then resealed yand ex
the switch. The solenoid or other operator when ener
gized, pulls the mobile contact away from the iixed con
tact to open the circuit. The bellows permits both move
ments without break in the vacuum of the enclosing
envelope.
‘
haustedV for further service.
Another object of my invention is the provision of an
A dielectric bearing tube in which the stem is slidably
journaled is iixed within the open end of the bellows by
hermetic sealing structure for the ends of an evacuated
a detachable part of the cover plate at that end. Electro
non-conductive shell in which atmospheric pressure is 55 static shields or baiiics surround the inner end of the
utilized as `an aid to rigidly secure the ends in permanent
assembly.
stem and the bellows; and to insure that vaporized con
tact metal will not adhere to the inner surface of the
glass shell and thereby form a conductive path between
Since the cost of labor, measured in terms of the time
the end assemblies, a sputter shield is mounted on'one
required to produce a consumer product, is an important
factor in determining the cost of the item to consumers, 60 of the end assemblies so as to surround the contact ends
of the ñxed and movable contact electrodes.
another object of the invention is to provide a switch struc
The arrangement of parts and the membranes Iasso
ture in which fabrication and assembly of the parts is
ciated with the mobile electrode is such that in the event
susceptible -to mass production techniques.
a part within this end of the envelope must be replaced
Still another object of the invention is the provision of
a non-conductive sputter shield of novel design surround 65 or repaired, the membranes at this end may be cut to
ing the switch contacts to prevent accumulation of vapor
give access, and then rejoined and the envelope again ex
ized contact metal on the envelope wall.
A still further object is the provision of Ia vacuum
hausted for further use.
switch incorporating means for easily applying localized
heat to the switch electrodes within the envelope during
the degassing cycle in order to more effectively and rapidly
mediate its ends to give access to the parts, after which
degas the switch electrodes;
' In detail my switch comprises a cylindrical glass shell
'
'
The use of glass for the shell
also makes possible the division of the glass shell inter
the shell parts may be rejoined and the envelope
exhausted.
3
3,026,394
.2 around the inside edges of which at each end is in
on the outer periphery of the annular plate 43.
tegrally fused a glass apron or flare 3, extending in
wardly to a bead 4.
Shell and flare are preferably of
heavy Pyrex glass which, of various dielectric materials,
has the desired transparency, mechanical and dielectric
strength, and heat resistance.
Arranged around both upper and lower ends, is an
annular two-part copper membrane comprising an in
wardly extending outer flange 6, having a generally cylin
drical integral inner return flange section 7 heliarc
brazed thereon, the outer flange thinning down into the
bead 4 in a conventional metal-to-glass seal; and the
inner flange extending to the plane of the associated
The
inner periphery of plate 43 is` also provided with a flange
44, the edge of which is brazed to a contiguous flange
46 formed on the collar 47, which in turn is hermetically
brazed about the open outer end 48 of bellows 49, ar'
ranged coaxially around the stern and bearing 3l. As
shown, this assembly is supported against atmospheric
pressure tending to crush it inward by detachably se--V Y
curing the plate 43 to the overlying heavy cover plate 36
by means of cap screws 51, which, like the correspond-_ing cap screws 23 at the other end of the switch, extend
through the plate and engage hermetically brazed reiriÄ
forcing caps 52 on _the inner surface of plate 435
The inner end 53 of the‘bellows is closed by and
'shell end. At the fixed electrode end of the switch this
edge is integrally united by the heliarc weld 8 to the up 15 brazed to the hollow stem intermediate its ends,_ and
wardly extending outer peripheral flange 9 on annular
thus continues the hermetic closure at this end of the
copper plate 12, the inner periphery of which is pro~
shell
while permitting axial movement ofthe stern. It
vided with an upwardly extending flange 13 which is
will be apparent from the drawing that Vcylindrical flange
integrally united to a second annular copper mounting
7 is proportioned to surround _the bellows andprotects
vplate 14 concentrically arranged contiguous to the inner
it from bombardment by particles emanating from the
periphery of the annular plate 12. An outer peripheral
flange 16 on plate 14 is heliarc brazed tothe flange 13
contact points.
onV plate 12 to provide a hermetic seal capable of being
subsequently opened. The inner peripheral edge lof the
annular plate 14 snugly surrounds and is integrally and
hermetically brazed to a fixed copper electrode 17 which
extends into the envelope and terminates at -its inner end
in a relatively larger diameter tungsten contact point 18.
As indicated in the drawing, the electrode 17 is pro
A horizontalY baffle or shield 54 sub=
stantially closing the inner end of cylindrical flange 7
provides additional protection for the bellows and helps
to disperse such particles toward thefixed end’ ofthe
shell. Particles that migrate toward the mobile end of
the switch are kept from reaching the bellows by the
substantially closed chamber within which it is enclosed.
As a further aid in controlling the movement within
the envelope of particles of contact metal, a spatter shield
vided with an axial bore 19 to accommodate a heating 30 56 is provided.
element during the degassing cycle. It has been found
that the application of high heat‘to they electrodes during
the degassing cycle helps to drive gas molecules from
The spatter shield is preferably fabri
cated from heat-resistant glassor other dielectric. In the
embodiment shown, the glass shield is fixed at one end to
the annular plates 12-14 at Ythe fixed electrode end of
' the electrode metal itself, so that such gas does not sub
the switch, by means of a metallic shell having a feathered
sequently escape into the evacuated envelope. The other 35 portion 57 joined to the shield in the conventional man
end of the fixed electrode extends out of the envelope
beyond the shell in a terminal portion 21 which may be
The other end of the shell constitutes an integral cy'd
ner.
connected to a source of power by any suitable means.
Overlying the end of the shell is a heavy end plate
22, to which the mounting plate 14 is tightly held by
p
lindrical portion 58 of smaller diameter and havin-g its
end remote from the shield integrally brazed to the inner «
and outer peripheries, respectively, of the annular plates
the cap screw 23. To thicken the plate at the point where
12 and 14. The end of the shield where it joins the shell _
the cap screws engage, interiorly threaded copper plated
portion
57 is relatively larger in diameter than its adjai
steel caps 24 are brazed on the interior of the plate 14.
cent Waist section, which is reduced in diameter as at 59
VMounting holes 26 are formed about the rim of the end
to form a restricted passage 61 through which the ñxed
plate; and for evacuation purposes a metal tubulation 45 electrode 17 must extend. Immediately below the waist
27, brazed in the mounting plate 14 extends through
section and approximately opposite the contacts 18-28,
the end plate as shown.
the shield is abruptly increased in diameter to provide
It Will be observed that this structure provides a her
a
large diameter chamber 62 surrounding the contacts.
metically tight end> for the shell entirely within it and
The lower free end 63 of the shield is reduced to about the
immediately below the end cover plate. So constructed 50 same diameter as the waist section 59, so that while fast
only a relatively small area including the metal-to-glass
traveling vaporized contact metal is permitted to be im
seal is subjected to unsupported atmospheric pressure. A
pelled
radially outwardly away from the contacts, the re
major portion of such stress is carried by the end plate,
stricted passage 161 and restricted end y63 of the shield
which in addition, supports the weight of the fixed con
effectively prevent migration of such particles in objec
tact, and receives the shock and thrust of the closing and
tionable
amounts beyond the confines of the chamber 62.
closed contacts.
It will thus be seen that condensation of the vaporized
At the other or lower end of the shell is the mobile
contact metal on the interior of the shield cannot result
contact 28 of tungsten mounted on the centrally bored
in
the formation of a conductive layer between opposed
copper electrode stem 29. The stem is slidably jour
and such condensation effectively prevents the
naled in a dielectric bearing tube 31, detachably fixed by 60 electrodes,
formation of such a layer on the interior surface of the
snap ring 32 on the bearing collar ‘3-3, which is detach
glass shell 2. It will also be apparent that the restricted
ably fixed by cap screws 34 on the detachable steel
open end 63 of shield 56 effectively cooperates with the
cover plate 36, which overlies the end of the shell in
closely adjacent baffle 5'4 and the cylindrical flange 7, to
abutting relation thereto. As with the fixed electrode,
the mobile electrode or stem extends outwardly beyond
the plate 36 in a terminal end 37 provided at its outer
end with a threaded bushing 38 integrally brazed in the
central bore for attachment of operating means, such as
a solenoid (not shown).
As previously described, this end also is hermetically
sealed by an annular copper membrane 6~--7 lmaking a
metal-to-glass union with the bead 4, and extending radi
ally inwardly, where the outer edge of the flange 7 is
protect the bellows against rupture by flying particles.
An actuator for the switch, such as a solenoid (not
shown) is connected by a link 64 to the hollow copper
stem 29-37. The end of the link is threaded into the
brass bushing 38 brazed into the free end of the stem
70 as previously described. No means is provided for hold
ing the end cover plates against the ends of the shell, since
atmospheric pressure after vacuumization of the envelope
is amply sufficient to fix them rigidly in place.
' While the structure of my invention has been explained
integrally heliarc brazed as at 41 to the flange 42, formed 75 above without reference to sequence of assembly, such
3,026,394
6
objects of my invention. Essentially it is as follows:
The annular membranes 6-7 are -ñrst beaded, the
flares 3 attached, and then the flares are fused to corre
sponding edges of two separate halves of the unitary shell
shown. At the mobile electrode end the plate 43, bellows,
baffle and stem are integrally brazed as a unit, and as a
unit inserted through the flange 7 and heliarc brazed at
41 to fix this assembly to the associated half-shell. For
convenience, and to protect the parts, cover plate 316,
bearing 31 -and bearing collar 33 may be applied at this
time to complete this end of the switch.
To close the open upper end of the envelope, the brazed
.
with, said second conductive end cap assembly being in
serted through lthe other of said cylindrical flange assem
blies and having the outer periphery of its annular plate
sequence is of great importance
5 in realizing some ofthe
brazed to the outer end of the adjacent cylindrically ex
tending flange and a portion of the hollow open end stem
of the fixed electrode protruding outward from the shell
and a second annular cover plate received over said pro
truding hollow fixed electrode stem in abutting relation
against the adjacent end of the shell and attached to said
10 annular plate of the second end cap assembly, said second
fixed assembly of membrane 6_7, joined to the associated
half-shell, receives the previously assembled and integral
ly brazed annular plates 12, 14, electrode 17 and attached
conductive end cap assembly being readily removable `
from said adjacent flange assembly by breaking its brazed
connection therewith after removal of said second cover
plate, said hollow electrode stems having a bore of a size
to accommodate a heating element therein to be placed
adjacent the electrode portion of the stem to help drive
gas molecules from the electrode metal portions during
shield 56. Heliarc brazing as at 8 ñxes this assembly to
degassing of said envelope.
the associated half-shell, after which the cover plate 22
2. A vacuum switch according to claim 1 wherein said
may be attached. The two shell halves are now mounted
in a glass lathe and the abutted ends of the half-shells in 20 first conductive end cap assembly has an annulai- collar
tegrally joined to form the unitary glass shell 2 as shown.
Evacuation of the envelope thus formed completes the
switch.
fitting within said first annular plate and the end of the
bellows is brazed to said annular collar rather than to
said first annular plate, an elongated dielectric bearing
tube extending through said annular collar and bellows
size and capacity described, it is very desirable that they 25 and receiving axially therewithin said mobile electrode
stem for sliding movement, said first colver plate receiv
be so constructed that if need arise the envelope may be
ing at its center and having attached thereto an annular
opened and inner parts be repaired or replaced. This is
bearing collar which receives therewithin said bearing
accomplished by removing the lower cover plate 36 and
tube, means holding said bearing tube within said bear
opening the heliarc welded joint 41, whereupon the mo
bile contact assembly may be lifted out. If it is necessary 30 ing collar, an annular baille plate received over said mo
bile electrode stern and extending transverse thereto and
to remove the fixed contact assembly, the shell 2 is
attached thereto inward of the end of the bellows attach
opened at about its midpoint and the assembly removed
ment to said stem, said baffle plate having a diameter
through the thus opened end of the half-shell. After re
slightly less than the diameter of the adjacent cylindrical
pair and reclosing, the envelope is once more vacuumized
35 flange assembly and forming therewith a shield of said
and the switch is again ready for use.
bellows to prevent sputter from said electrodes from
I claim:
reaching said bellows.
1. A vacuum switch constructed for ease of assembly
3. A vacuum switch according to claim 2 wherein said
and repair comprising a vacuumized envelope including
second conductive end cap includes a cylindrical metal
a dielectric shell having annular inturned ends and first
and second conductive end caps hermetically sealing op 40 sleeve attached at one end of the annular plate thereof and
extending inwardly in the shell and in spaced relation
posite ends of the shell, each of said end caps including
within the adjacent cylindrical flange assembly and a
a cylindrical flange assembly comprising a cylindrical in
cylindrical dielectric shield attached to the other end of
wardly extending ñange and an outwardly extending cy
said metal sleeve and extending freely about said electrode
lindrical flange integral hermetically at its inner end with
lthe inner end of said ñrst mentioned flange and its outer 45 portions to prevent sputter therefrom reaching said sur
rounding shell.
end hermetically joined to an associated in turned end
4. A vacuum switch according to claim 3 wherein said
of the shell whereby the cylindrical flanges lie within the
Because of the high cost of making a switch of the great
confines of the shell at the ends thereof, said first con
ductive end cap comprising in part an assembly of an an
nular plate, a bellows attached at one end to the inner.
annular opening of the end plate, a hollow elongated
mobile `electrode stem extending through said annular
plate and attached intermediate its ends to the other end
electrode portion contact at a contact locus within the
shell and wherein said cylindrical dielectric shield is
provided with a radially constricted shield section axially
spaced from the electrode contact locus and radially
distended shield section opposite the contact locus.
5. A vacuum switch according to claim 4 wherein said
cylindrical dielectric shield has a second radially con
of the bellows and having an electrode portion at the
stricted shield section axially -spaced inward from the first
inner end thereof, said first conductive end cap assembly
contricted portion and axially spaced beyond said con
being inserted through one of said cylindrical flange as
tact locus from ‘said first radially constricted section of the
semblies and having the outer periphery of the annular
shield whereby the contact locus is substantially encom
plate brazed to the outer end of the cylindrical inwardly
passed by the dielectric shield.
extending flange with a portion of the hollow open end 60
6. A vacuum switch according to claim 4 wherein said
stem of the electrode protruding outward from the shell,
second conductive end cap has the `annular plate there
a ñrst annular cover plate received over said protruding
of comprising an inner and an outer coaxially arranged
hollow stem in abutting relation against the adjacent end
annular plate portion each having axially extending an
of the shell and attached to said annular plate, said first
nular
flanges thereon in abutting relation, said abutting
conductive end cap in said part assembly being readily 65 flanges being connected by brazing, the outer of said
removable from said flange assembly by breaking its
»annular plate portion having an outer peripherial annular
brazed connection therewith after removal of said first
flange brazed to said surrounding cylindrical flange as
cover plate, said second conductive end cap comprising
sembly Iand wherein said cylindrical metal sleeve is con
in part an assembly of an annular plate and a hollow elon 70 nected to the second end cap assembly at the juncture
gated fìxed electrode stem extending through said annu
of said first and second annular plate portions by brazing
lar plate in axial alignment with said mobile electrode
thereby permitting ease of manufacturing assembly and
stem and brazed to the last mentioned annular plate inter
disassembly for repair.
mediate its ends and having an electrode portion at its
inner end adjacent the mobile electrode for contact there 75
(References on following page)
3,026,394C
8
References Cited in the íìle of this patent
UNITED STATES PATENTS
' 1,784,302
Y 2,740,915
2,794,101
2,863,027
2,864,998
Míllikan et a1. ________ __ Dec. 9, 1930
Jennings ______________ __ Apr. 3, 1956
Jennings ______________ __ M-ay 28, 1957
Jennings _____________ __ Dec. 2, 1958
Lee _______________ __`_ Dec. 16, 1958
2,900,476
2,920,169
Jennings ______ __’________ Jan;y 5, 1960
407,725
Germany _____________ __ Jan. 2, 1925
287,843
355,535
787,846
Great Britain __________ __ Aug. 2, 1928
Great Britain _________ __ Aug. 27, 1931
Reece _______________ __ Aug. 18, 1959
FOREIGN PATENTS'
5
_
Great Britain _________ __ Dec. 18, 1957
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