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Патент USA US2132920

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Oct. 1l, 1938.
P. s'. BEAR Er'AL '
‘ ' `2,132,920
Filed Aug. 5, A1935
- 2 Sheets-sheet 1v
Oct. ll, 1938.
P. s. BEAR Er AL
Filed Aug. 5, 1935
2 Sheets-Sheet 2
Patented Oct. 11, 1938
swrron y
Paul S. iìear and Herbert EÍ Bucklen, Elkhart,
Ind., assignors to Bucklen-Bear Laboratories,
Inc., Elkhart, Ind., a corporation of Indiana
Application `August 5, 1935, Serial No. 34,682
(Cl. 20o-_152)
26 Claims.
Our invention is concerned primarily with
switches of the mercury contactor type, and par
ticularly with switches having a metallic switch
envelope in place of the glass type envelope for
5 merly employed. which has sealed-in metallic
electrodes, although certain features of the pres
ent invention are applicable to such glass en
velope switches.
The specific embodiments herein disclosed ,are
l0 heavy duty switches suitable for a heavy schedule
of switching- of power current. While our inven
tion is especially useful for heavy duty switches,
certain phases of the invention are equally ap
plicable to light duty or small capacity switches.
In mercury switches of the glass envelope type,
the envelope is either evacuated or provided with
a filling of hydrogen, neon, or a similar gas,
usually under pressure. There are distinct dis
advantages in both types of glass envelope
20 switches, since the inability to dissipate heat re
sults in excessive temperature of the inleads'A
with resultant leakage about the seal. Such leak
age admits oxygen to the interior of the envelorîe,
resulting in rapid deterioration of the switch. or
25 explosion of the hydrogen filling.
to permit inñltration of air, causing oxidation of
the inner surfaces of the shells.
ì Attempts have been made to fill suchswitches
with hydrogen gas, but hydrogen gas is very dif
ficult to retain. Hydrogen will leak through pores 5
that will not pass other gases. It has also been
attempted to employ liquid ñlls in such switches,
but thus far no commercially practicable liquid
fill switches have appeared on the market or
been available. We have found that liquid iilled 10
switches prior `to our present invention would
almost invariably explode upon continued inter
"rupting operation at their rating, or upon over
Our present invention contemplates a mercury 15
switch of the sealed envelope type, in which the
interior of the- switch envelope is cleaned
thoroughly prior to assembly, and kept clean dur
ing operation. In the preferred form of our in
vention we employ a cup-shaped metallic shell 20
which has a ceramic insert sealed in one end
thereof and having an electrode carried thereby,_
the shell itself serving'as the second electrode.
In order 'to reduce the localization of heat
generated by the arcing produced during opening 25
The chief disadvantage of glass envelope ' and closing of the switch as much as possible, we
switches of the mercury type is that there is a .4 provide a switch construction in which this gen
considerable difference in the coeilicients, of
thermal expansion of the glass and of the' me-.
eration of heat takes place away from the metallic
switch parts. 'I'his greatly reduces the tendency
30 tallic electrodes. vThis results in a definite limi
tation of the size of the electrode that can -be
for pitting and oxidation of the metal. This con- 30
struction also secures the beneficial action oi’
employed, directly limiting the current carrying
capacity of the switch, since heating of the elec
a mercury to mercury making and breaking of
the contact. Also, our present construction re
moves this generation of heat as far as possible
from the point of sealing of the ceramic insert 35
trode produces severe strains in the glass sur
35 rounding its point of entrance into the switch, and
in most cases results in loosening of the seal or
into the open end of the shell, serving to protect
cracking of-the envelope, both of which results
this seal from the heat.
are disastrous to the life of the switch.
This has induced a tendency to use _metallic
1 40 shell type mercury switches, but such construc
tions present other disadvantages limiting their
use. With a metallic envelope type of switch,
there is diiiiculty in keeping the parts free of im
purities, and surface oxidation particularly, dur
45 ing the assembling process. Impurities tend to
foul the mercury as_well as the contact sur
faces, and tend to increase the contact resist
ance. Also, where a thin metal section is em
ployed, the thermal capacity is low andthe rate
50 of heat transmission is 'limited thereby. In such
constructions the heat generated by a rapid suc
cession of makingand breaking of relatively high
currents cannot be readily dissipated,»causing
uneven heating up of the parts and tending to
65 break the seals about the electrodes. This tends
_ One of the primary objects of our present in
vention is the use of a liquid iill which is limited
in volume with respect to the vapor space in 40
the switch envelope. This limited liquid ñll to
vapor relation is of distinct advantage in con
nection with several phases of this type of switch
construction. In the first place, the liquid iill
which dwe preferably employ is a slightly viscous 45
liquid having a relatively high boiling point. The
preferred liquid is triethanolamine. We may
utilize a mixture of castor oil and alcohol. We do
not wish to be limited to the above named liquids
as others may be employed but the foregoing 50
appear to 'ne-suitable for this purpose.
Only a limited quantity of such liquid is em
ployed, the major portion of the interior ofthe
switch envelope being employed as a vapor cham
ber. Upon slight heating of the liquid iill by 55
the making and breaking of contact within the
switch, the liquid starts to boil, and the vapor
ramic shell type switches; and
modified form of electrode and stud.
respect to the _volume of the chamber produces the
beneficial action, that the liquid fill upon boiling
v10 and subsequent condensation acts as a highly
chamber lbecomes filled with vapor which con
denses on the defining surfaces of the envelope
and runs back as' a liquid into the main body of
The use of alimited amountr of liquid lill with
Figure 8 is a sectional view through a modified
type of metal shell switch;
Figures 9 and 10 are similar views through ce
Figure 11 is a fragmentary section through a
Referring now in detail to’the drawings, in
Figure 1 we have provided _a substantially cup- '
shaped metallic shell I0, having an outwardly
flared open end portion I2 adapted to receive the
effective medium for dissipating heat generated ceramic insert I3, preferably porcelain of the wet
at a localized 'point in the switch uniformly to ' process type; which insert is provided with an
all parts ofthe envelope, whereby the heat is outwardly flaring tapered spillway -or runway I4
rapidly conducted away from the arcing point and extending into the shell I0 toward the closed end
dissipated throughout the switch. This prevents thereof. The shell I0 is preferably a drawn sheet
the temperature at the heat generating point from metal member formed of iron or stainless steel
rising above the boiling point so long as `there is I or alloy of iron.
liquid in >contact with the heated part.
The insert I3 is provided with an annular disc
Another beneficial action secured by the use of or ring member I5 of iron, stainless steel or alloy
a relatively large vapor space in the envelope of iron forming an electrode, which member is 20
compared to the amount of liquid ñll employed providedl with a threaded stud I6, also of iron,
resides in the limitation of the vapor pressure stainless steel or alloy of iron, extending out
which can be generated by converting all of it to wardly through a tapered opening formed sub
a vapor.
' f
stantially coaxially of the spillway I4 and extend
Still another beneficial action secured by this ing outwardly of the ceramic insert I3. The stud 25
limitation ofthe liquid fill resides in the reduction I6 is secured in position to hold the electrode I5
of resistance to movement of mercury contactor, in proper position by means of al washer member
since it does not have to displace any appreciable
I1 and nut I8 threaded thereon and bearing
quantity of liquid during its movement into and , against a suitable resilient conical gasket or pack
ing member I9, which is compressed axially in 30
30 out of lcontacting engagement. The use of a liquid
ñll of this type is also advantageous in that as
order to expand it radially. This gasket or pack
the pressure builds up inside the envelope, due to ' ing member I9 preferably is formed of natural
the heat of the arc, the arc value is thereby re
duced by the increased pressure, preventing the
35 formation of any appreciable’ arcs during rapid
operation of the switch.
or artificial rubber or like impervious expansible
material, or any other suitable material. A suit
able recess permitting llateral expansion at the
outer'end of the conical-packing member 49 may
The particular characteristics and advantagesl >b_e provided forkeeping the rubber undercom
of liquid fills as to their action on the metallic
surfaces and the like are fully disclosed in our
40 copending application, Serial No. 745,842, filed
September 28, 1934.
Another feature of the present invention 'is the
simplified, compact and eflicient switch structure
which we employ in connection with the concept
45 of limiting the liquid fillÁ to vapor relation. The
structure which we herein disclose is designed to
,utilize the advantages of the limited liquid fill but
obviously many, if not all, of the advantages may
be realized in other structures or types of struc
tures, though generally less in degree.
Other objects and advantages of the present
invention will appear more fully from the follow
pression without completely filling -the available
space. . This allows the washer 41 to rest against
the ceramic I3. Alternately, the. washer 41 may 40
rest solely upon the end of the rubber gasket 49. ‘
A conductor 20 is soldered or otherwise suitably
secured to'the outwardly extending end of the
stud I6.
The electrode I5 is disposed within a substan
tially cylindrical recess 22 formed at the rear
end of the outwardly flaring spillway I4, the re
cess 22 providing 'a retaining ring or groove
adapted to carry a small body of mercury 23
therein which is in engagement with the elec 50
trode I5, and which is adapted to .have contact
ing engagement with a second body of mercury
ing detailed description, which, taken in oonnec- _ 24 upon tiltingof the switch to move the body of
- mercury 24 up the inclined spillway I into con
tion with the accompanying drawings, will dis
55 lclose to those skilled in the art the particular con
struction and operation of a preferred embodi
ment of our present invention.
In the drawings:
22 lprovides a lshoulder, the vedge of _which is
Figure 1 is a vertical sectional view .through one
form of switch `embodying the principles of the
present invention, the switch hereshown being
a‘low angle switch;
AFigure 2 is a view similar to Figure 1, through a
modiñed type of switch, this switch being a high
angle switch;
Figure 3 shows the ,switch of Figure 2 in the
other of its operating positions;
tact with the body of mercury 23.
'I‘he junction of the spillway I4 with the recess
sharp and includes a solid angle of 'less than 90°
whereby accurate repeat perfomance is secured.
In assembling the component> parts of the 60
switch, the insert I3, is secured in the :flared end
I2 of the shell I0 by means `of a sealing gasket
25, which may be formed of natural or synthetic
rubber or other suitable material, and which is
compressed partly axially and partly radially and 65
laterally of the tapered surfaces 26 and 21 of
the insert when the insert is moved into position
Figure 4 is a sectional view taken‘substantially y' within the end of the shell I0.
on line 4-.4 of Figure- 2, showing the internal
A suitable me
tallic retaining ring 21' of frusto-conical section
70 construction of th'e switch;
is carried »by the outer end of the insert, and the 70
Figure 5 is a detailed view of a modified type of outwardly defining edge of the flared portion I2
insulating sleeve embodied-in the switch shown in of the shell III-is spun inwardly over the longi
tudinally extending end of the gasket 25 and
Figures 6 and 7 are corresponding views of 'ring 21', as shown- at 28, vto compress and dis
75 still further modified types of insulating sleeve;
place the gasket into final position to seal the 76
Figure 2;
with the relatively cool walls _throughout the re
insert within the shell. The spun-over edge 28
serves to prevent displacement of the insert I3
outwardly of the shell i0 by internal pressure.
mainder of the switch envelope, is condensed,
and runs back down the side wall of the envelope
A slight expansion space for the lend of the rub
into 'the main body of liquid iill. _ This ebullìtion
ber gasket 25 should be allowed near or at ring 21’.
of the liquid fill and the subsequent condensa
' The shell I0 forms the second electrode for the ' tion of the vapor, due to the use of a definitely
switch, having secured thereto a conductor 29
which may besoldered or otherwise suitably se
cured to the external surface of the shell l0, as
10 indicated at 3B.
In the assembly of the switch structure shown'in Figure 1, the closed and rounded end 32 of
the shell I0 is provided with a threaded‘inward
ly extending portion receiving the closing screw
15 or sealing plug 33. When the insert, with its
y electrode fixed in position, is sealed within the
open end of the shell, the shell is tipped upward
ly with the end 32 thereof disposed at the top
of the switch, and the mercury 23 and 24, of a
20 predetermined amount, is placed in the switch
envelope through the opening closed by the plug
33. A suitable quantity of liquid ñll, indicated at
35, is then forced into the interior of the shell I0,
the interior of the shell beingfirst evacuated to
25 produce a relatively high vacuum therein, and
being washed in any suitable manner to drive
out any occluded gases or the like. Before the
liquid fill has been introduced, and with a vac
uum in the chamber, the chamber may be filled,
30 preferably under a slight pressure, with any suit-‘
limited quantity of ñll, prevents any excessively
high rupturing pressures within the envelope,
even if all of the liquid vaporizes.
We preferably employ triethanolamine as the
liquid ñll, this liquid having a relatively high
boiling point and having the characteristic of
maintaining the switch surfacesclean and free
from foreign materials. If desired, however, a
mixture of castor oil and alcohol may- be em 15
ployed, the castor oil being employed in the form
commercially known as “_Ricinine”. Any’liquid
of this class which is anhydrous, alkaline in re
action, possesses arc extinguishing character
istics and has about the same viscosity and boil
ing point, may be employed.
It will also be apparent that the generation of
heat at this acute breaking angle will be trans
mitted directly to the liquid ñll, and by reason of
the vaporization of this liquid fill will be'dissi 25
pated substantially uniformly throughout the `en
tire switch envelope, whereby the entire surface
of the metallic shell I0 can be used for heat con
duction away from-the point of generation of `
heat, whereby the heat will be rapidly dissipated 80
to the surrounding atmosphere. Thus the lim
able gas which is substantially inert or non
cor-rosive with respect to the metal and with re- ' ited liquid ñll performs three important functions
spect to the liquid ñll. This may be neon, argon,
nitrogen, carbon monoxide, hydrogen helium, or
35 the like. The amount of liquid fill 35 which is
inserted is predetermined with respect to the vol
in a switch of this type, namely, a maintenance
of a relatively low pressure, less than the ruptur
ing or leakage pressure caused by its ebullìtion due 85
to the heat generated by arcing of the mercury
ume of the interior of the switch envelope. In
a preferred embodiment of the invention the
quantity of liquid fill for a switch envelope hav
4.0 ing approximately a 21 cc. volume comprising
about 0.5 cc. of liquid iill, which, together with
the mercury and the like, provides for approx
to mercury contact; secondly, its use as a heat l.
45 the internal volumeof the switch chamber is 21
cc. and approximately 7 cc. of ‘mercury is employ
the arcing time, or the length of the arc, de 45
creases. By maintaining the volume of liquid fill
transferring medium for dissipating the localized
heat generated by thearc within the switch to all
points of the switch envelope; and thirdly, the 40
reduction of the arcing time due to the increased
pressure within the switch envelopeV caused by
evaporation of the fill, whereby upon increased
imately 13.5 cc. of vapor space within the cham
ber. In a preferred embodiment of our switch, -rapidity of operation the pressure increases and
ed as a contactor.
The liquid ñll may run any
employed relatively small with respect to the vol
where from 1/2 cc. to 1 cc., leaving a vapor space
ume of the vapor space indicated at 35, it occupy
of approximately 64% of the total volume of the
We have shown the liquid as
exaggerated in amount in the drawings, for the
sake of illustration. In practice, the liquid has a
tendency to spread and wet all of the inside sur
face of the container. The liquid- _film is shown '
ing only about 3% of this volume, it is apparent
that high internal pressures within the switch 50
envelope will not be developed even though all,
or substantially all, of the liquid ñll be vaporized.'
Thus by the limited liquid fill both hot spots
which are particularly destructive of glass en
velope switches and high' pressures which are de 55
50 switch chamber.
55 as of an exaggerated thickness, for purposes of
When the connection tothe opening into which
the closure plug 33 extends is removed, a por-v
tion of this gas escapes, providing a vapor space
60 above the liquid ñll 35. The closure plug 33 is
then immediately screwed into place and the en
tire external surface of the switch envelope and
the ceramic insert may be coated with a coating
of “Bakelite”, cellulose aetate, or the like.
65 .It will be noted, in this embodiment of the in
vention, that the making and breaking of con
‘ tact occurs at the acute angle formed between
structive of all forms of switches are avoided or
greatly reduced.
It is to be observed that our system of internal
circulation of the liquid flll is unique. The liquid
forms a viscous film in contact with the internal 60
surfaces and particularly with the mercury, which
is always subject to heat generation by both the
flow of current through it and by the arc produced
at either making or breaking of the circuit.
This film of liquid is vaporized locally, i. e., at
the point where heat is generated. The vapor
tends to fill the entire vapor space and selectively
the sloping spillway I4 and the side wall defining ‘ flows to the coldest region because it is there most ` '
the cylindrical recess 22. Thus, the heat gen
70 erated is generated at a point removed from the
metal itself, and inasmuch as the liquid fill
surrounds, or at least wets, this particular point
of making and breaking of Contact, the liquid
fill is heated to’ an extent such that a portion of
75 it vaporizes. This vapor then comes into contact
rapidly condensed. ‘By the employment of a liq
uid the boiling point of which is at a substan
tially higher temperature than that of the sur
rounding air, i. e., by providing a substantial tem
perature differential, the heat of vaporization
which is given óñ by the vapor in condensing on
the inside surfaces is readily dissipated.
' 4
2, 1312,920
_The condensed liquid, being viscous, runs back
slowly, and thereby tends to give oif heat in ex
cess of the heat of vaporization, i. e., a substantial
part of the heat of the liquid. Thus the viscosity
rends to regulate the rate of circulation of the
iiquid back to the point of heat generation by
gravity. The liquid of the thin layer or ñlm is
- thus elevated by heat, i. e., vaporization, and de
livered to the point'where it liqueñes and returns
Thus there is an internal circulation
of the liquid in the switch. This action is highly
z advantageous, and is particularly useful in heavy
duty metal' shell switches.
There is a peculiarly useful feature in the con
15 stitution of the liquid flll as above disclosed. The
10 by gravity.
high boiling point, viscosity, and the limitation of
amount provide an ideal coordination of features,
' for Anot only is the heat easily dissipated, but the
rise of pressure is also limited.
20 ` - In the construction ci the porcelain insulator
I3 it is advisable to construct the same of two
parts joined together because of the 'diñìculty
otherwise encountered in producing the sharp an
nular shoulder and the annular recess 22. The
25 joint between the two parts is made preferably at
a point along the length of the recess 22 where
the gasket or seal 25 will prevent any possible
leakage of the joint from communicating with the
outside; Thus an imperfect joint between the
two porcelain parts does not destroy the useful
ness of the switch. The parts may be produced
and ñred and then cemented together or they may
and the head end of the stud 45. A second body
of mercury 5.4 forming the rest of the liquid fdl
is carried withirrthe shell 40 about> the outer
surface of the ceramic sleeve 44, the two bodies of
mercury being adapted `to have contacting en
gagement beyond the outer end of the ceramic
Asleeve 44 when the switch is tilted about its longi
tudinal axis. The insert 43 is secured within the
open end of the shell 42 in the same manner as
described in connection with Figure 1, there being 10
a suitable resilient gasket 55 and clamping ring
55’ interposed therebetween, the outer edge 56
of the shell being spun over the rear portion of
the gasket and about the outer surface of the ring
to retain the insert in cushioned sealed engage 15
ment within the end of the shell 40 substantially.
A second conductor 51 is secured at 58 to the
external surface ofthe Vshell 40, whereby control
of the circuit through the conductors 55 and 51 is
provided by movement of the bodies of mercury 20
53 and 54 within the switch. 'I'he closure plug 59 ~
corresponds, to the closure plug 33 of Figure 1,
and is employed in the same manner.
A suitable liquid fill 60 is introduced into the
interior of the switch’envelope, and is so propor 25
tioned with respect to the vapor space 62 that ‘
free ebullition of the ñll is provided for washingV
the'internal surfaces of the shell 40, the sleeve 44
and the-tubular electrode 45, as well as the mer
cury itself. This vapor space 62 also provides for 30
free transmission of the heat generated at the
outer end of the sleeve 44 due to rnaking and
be joined before firing if desired.
breaking of contact thereover between the bodies
The electrode I5_it will be observed
adapted , of mercury 53 and 54, to ali parts of the switch
35 to engage the mercury both on its axially facing envelope, whereby no loeaiized points of heat
or end surface and on its radially facing or side generation are allowed to build up.
surface. This radial bearingJr or contact reduces
In the operation of the switch shown in Figures
the contact resistance between the electrcde..and ‘ 2 and 3, when the switch _is in the position shown
the mercury with minimum amount of mercury in Figure
the circuit is broken between the
in the recess 22 while preserving the desired re
bodies of mercury 53 and 54, which are in respec 40
tive engagement with the electrodes 45 and 40.
Considering now Figures 2 to 4, inclusive, the ' Upon tilting of the switch in a counterclockwise
peat performance.
switch shown-in this embodiment of the invention
comprises a drawn metallic shell 40 of iron, stain
’ less steel or suitaole iron alloy, having the flared
directionabout its longitudinal axis, as shown in'
Figure 3, the twofbodies of mercury 53 and ,54
both move forwardly with respect to the end of 45
end 42 adapted to receive a ceramic insert 43 of v the sleeve 44, »and come into engagement about
porcelain or the like, the insert 43 having a for
wardly extending substantially cylindrical sleeve
portion44, which sleeve portion is adapted to re
50 ceive a tubular sleeve electrode 45 which may beof drawn sheet metal ofthe same material'as the
shell 40 and which electrode is carried by the
headed end of a shank 46 extending outwardly
through the rear end of the insert 43. The sleeve
lss 45 and the shank 46 are secured in fixed position
with respect to the insert 43 by means of the
washer 41 and nut 4e threading over the extend
` ing end of the stud ë‘ô, there being a suitable lre
silient conical rubber bushing or gasket 49 inter
60 posed about the stud and compressed ,and ex
pan-ded within the defining wedge-shaped open
ing in the insert through which the stud extends
by endwise pressure of washer 41. A suitable
electrical conductor 50 is soldered or otherwise
65 secured tc the outwardly extending end of the.
stud 46. The sleeve 45 may be made of iron or
stainless steel or the'like with a copper stud,46
the defining edge of this’ sleeve, thereby closing
lcontact between the electrodes 45 and 4l). It will
be noted that the point at which contact is rnade
and broken `is about the defining edge c-f the
ceramic sleeve 44, spaced away from the ceramic
43 and from t-he inner> surface of the shell 40.
This provides for generation of heat at a point
removed from the electrode seal 49, and from the '
ceramic seal 55.
In addition, it removes the point of generation
of heat away from any of the metal surfaces of
the electrode 45 or electrode 40, and consequently
provides for free action of the liquid fill 60
dis- '
»sipating this heat to all parts of the -switch enve 60
lope, and preventing building up of localized
heated spots. Also, due to the definite relation
of ‘the sleeve 44 withv respect to the shell 40, a
positive opening and closing of contact at the
same points of inclination is assured, thus giving 65
“repeat” performance, that is, the opening and '
closing oi the switch at the same angular posi
brazed to the end ivall thereof, as shown as a
tions -for successive operations of the switch.
modification in Flgure ,11.
Referring now to Figure 5, we provide a ceramic
sleeve 44", which may correspond to the ceramic "
It will be noted that Ithe cuter end of the tubu
lar sleeve electrode 45, indicated at 52, is dis
sleeve 44 of Figures 2 to 4, inclusive, but which is
posed inwardly of the end of the ceramic s‘ieeve
_44, and that a body of vmercury 53 forming part
tending end of the sleeve 44', which‘is provided
' 'of the mercury fill is carried within this sleeve in
75 engagement with the inner surface of the sleeve
not as great in longitudinal extent. To the ex
with the, annular shoulder 65, we secure a modi
fledtype of breaking edge, which is shown as a 75
'substantially cylindrical sleeve 86 having an in
wardly extending tapered portion 61 at the outer
end thereof, the sleeve 86 being provided with ex
tending cylindrical iia'nge portion 68 extending
about the shoulder 65, the sleeve-66 being secured
ing provided with an outwardly flaring recess 95
receiving the compressible sealing gasket 96 for
sealing the shank of they electrode with respect
to the insert.' As here shown, the washer 93 rests
against the end of gasket 95 only.
A predetermined body of mercury 91 is dis
posed on the iioor of the switch envelope, and
edge formed by the tapered surface 61 is con
siderably wider in extent, that is, is radially `it will be noted that the lower surface of the .
f tothe sleeve` 44' by cementing.~ The breaking
thickened toprovide for slow motion operation
10 of the switch, whereby the .two bodies of mercury
53 and 54 will not come together with as great a
rapidity as provided merely by the sleeve 44.
Optionally this edge may be cut back, as shown
in Figure '1, to increase the acuteness of the
breaking angle.
electrode head 89 is positioned substantially at
the lower edge of the head approximately .015” io
lower‘than 'the meniscus height of the mercury
91, 4whereby the mercury' will make contact be- '
tween the shell 80 and the electrode 89 Without
ñrst engaging the ceramic 84. The floor of the
envelope is thus maintained level and no'uphill 16
rolling of the mercury is necessary.
The in
- In Figure 6 we show a still further modified
-form of breaking edge, comprising a sleeve' mem- _ eluded angle of operation of such a switch can
ber 10, having a suitable recess Íportion 12 for
receiving the end of the stub porcelain sleeve
20 44', and having a double rounded outwardly ex
tending defining edge 13, which provides a spill
_ over or snap operation of vthe switch; due to the
fact that the two bodies of mercury snap over
the rounded portion of thè-edge 13 and come into
engagement in a direction substantially normal
to their original direction of movement. This
provides for engagement ofthe mercury at an
be maintained within 1/¿°. The interior of the
envelope is provided with a partial fillingA of tri
ethanolamine, or a similar liquid having equiv 20
alentproperties, as indicated at 98, in the man
ner _described in connection Awith previous em
bodiments of the invention.
Figures 9 and 10 are directed to a switch of
the ceramic shell type, and disclose switches of
the same general construction as indicated by
corresponding reference numerals. Thus we pro
vide a ceramic cup-shaped shell |00 having an
accelerated speed of engagement, which pro
duces a sufficient impact to completely close annular _externally thickened portion |02 adja 'so
30 the circuit without any frying or sputtering be ~cent its open end.A The closed end of the shell
|00 is adapted to receive an electrode button |03
tween the advancing edges of mercury as the having
a shank portion |04 extending through
switch should be> slowly tilted. It isl to be ob
the shell and sealed with respect to the shell
served that. in the forms shown in Figures 2 to by the tapered gasket |05 which is axially com
7, both bodies of mercury have movementtoward l pressed'into sealing position by the nut |06 en 35
35 and away from eachother, with the resultant
gaging the outer end of the shank |04.
double speed of engagement and separation.
At its opposite end, the shell |00 receives the
In the embodiment of the invention shown in closure cap |01 having the annular clamping por
Figure 7, we provide a still further modified type tion |08 provided with a spun-over edge |09 en
. . of breaking edge comprising the sleeve 15 having
40 the cutaway annular ring portion -16 for cement
ing the same to the end of the stub shaft 44', and
provided with an externally chamfered acute
angle breaking edge 11, cut back from the inner
defining periphery of the sleeve 15. This edgev
45 forms a definite and positive point of separat
ing the mercury, whether moved rapidly or rela
.tively slowly, and thereby permits repeat per
formance, i. e., the feature of making and break
ing contact at the same angle'at all times. This
50 feature we believe to be unique in this sleeve
type of switch. The present switch requires to
- be held in no particular angular position about
its axis, since it is symmetrical with respect to its
longitudinal axis.
In Figure 8 we have provided a switch requiring
gaging the frusto-conical washer ||0 for com
pressing the resilient gasket ||2 into tight seal
ing engagement with the external tapered sur
faces of the portion |02 of the shell. Welded, or
otherwise suitably secured to the inner surface
of the cap member |01, is a tubular sleeve mem l45
ber I I3 having a relatively snug fit in the interior
of the shell |00 and being closed at its opposite
end across the inner face'of the cap member |01.
A suitable filler opening is formed in the mem
bers |01 and II3, and is closed by the iiller plug 50
Referring 'now speciñcally to Figure 9, a body
of mercury ||5 is disposed within the envelope
comprising shell'l00 and sleeve H3, and upon
tilting of the envelope the mercury is adapted to 55
move toward and away from the electrode button
only a small operating angle. In this construc
|03, which is preferably formed of stainless steel’
tion the metal shell 80 is provided with the usual ' or
other metal not wet by the mercury. This
filler opening 82 and sealing plug 83. At its open
contact'- between the sleeve ||3 _and
end the shell 80 receives the ceramic insert 84 button |03, and controls the circuit through the
60 cushioned in sealed engagement within the shell two flexible leads ILS and ||1 electrically con
by means of the annular tapered compressible
gasket 85 and the frusto-conical ring 86 which nected- to the button and the sleeve. Suitable
is pressed longitudinally against the gasket by the liquid iill is introduced into the envelope, as in
dicated at ||8, to take care of heat dissipation
spun-over edge 81 of the shell 8|).`
the like.
In Figure 10 we have modiñed the construction
a second electrode stud 88, having an inner hemi
` spherical head portion 89, preferably formed of ` to produce va switch having a larger operating
a non-wetting metal, such as stainless steel, pro
jecting outwardly of a central boss 90 formed'on
70 the insert. The surface of the insert adjacent
the boss 90 is annularly recessed, as at 92, to posi
tion the head 89 of the second-electrode inwardly
-\ of adjacent portions of the insert.
'I'he stud 88
is secured in position by a washer 83 and nut
75 94 engaging the outer end thereof, the insert be
angle and having mercury-to-mercury making
and breaking contact. The button |03 ‘of this
vembodiment is provided with a` substantially 70
hemispherical cup member -|20 held in the closed
end ofthe shell |00 by the electrode |03. An an
nular insulating ring |22, having an'internal
frusto-conical spillway surface |23, is inserted
into position with the small end of> the spillway
adjacent the> cup |20, whereby a small body of? larged open end, a ceramic insert in the open
mercury |24 is trapped on the inner surfaceoi’ end of said shell, ,resilient sealing means com
the cup behind the vertical edge |25 of the ring .pressed radially between said insert and the in
|22. 'I'he ring |22 is cemented or otherwise terior of said enlarged opened end, a ceramic
suitably secured in position.
The sleeve ||3 and cap member |01 are as.
sleeve extending longitudinally inwardly from
said insert and of a diameter substantially less
sembled' `in position in the manner- previously than the internal diameter of said shell, a tubu
described, and the body of mercury .||5 is intro
lar electrode Áwithin said sleeve and abutting
duced into the switch envelope. In the operation .against the insert at the insert end of said sleeve.
10 of the switch to close the circuit, the 'mercury
an extension of- the electrode supportingV said 10
||5 moves to the left, up the surface |23, and electrode in position and extending outwardly
then, due to its accelerated movement up the .centrally of said insert, compression seals of
converging surface, rushes into contact with the> yielding material for sealing the ceramic radially.
mercury |24, closing'the circuit through the
within the open end of said shell and sealing said
electrode with respect to said shell, a body of 15
vmercury moves down the diverging surface with mercury'in said shell and adapted to make and
increased momentum, until finally the gravita
break contact between said electrode and shell
tional pull'overcomes the cohesion between the over the extending edge of said sleeve member,
bodies |24` and ||5, and themercury is parted and an anhydrous alkaline liquid fill in said.
20 over the sharp edge between surfaces |23 and -shell for dissipating heat
from said edge to all
|25, whereby the surface tension snaps the ?ad
parts of said shell.`
jacent contiguous edges into receded position.
'2. A switch of the metallic envelope type com
Thus a substantially snap action type of switch ` prising a >tubular cup-shaped metallic shell hav
is produced.
ing an enlarged open end, a ceramic insert clos
„ It will be noted that in both Figures 9 and 10
ing the open end of said shell, an annular rub
the actual making and breaking of `the circuit ber gasket compressed between -the external an 25
occurs at a point removed from the gaskets ||2, nular surface of said insert and the exterior
whereby the'gaskets are disposed at the relatively surface of the open end of said shell, an integral
switch. Upon opposite tilting of lthe switch, the
cylindrical sleeve extending longitudinally from
'It is of paramount importance that the rela - said insert into said shell, an annular electrode
tion of the volumeY of liquid ñll to the `volume of surface engaging the interior of said sleeve inter
the vapor? chamber> be accurately controlled in mediate the ends thereof, a stud securing said
order that proper limitation of pressure during
in said sleeve and extending outwardly
heating be obtained. The liquidñlm provides electrode
through said insert, a rubber gasket about said
35 for cleansing of the internal surfaces of the lstud and compressed against said insert, an
switch envelope and keeping them clean. .The integral flange'on said insert surrounding said 35
vapor produced by boiling, and its condensation, stud and extending axially outwardly beyond the
provides for rapid dissipation of heat from a end of said shell, and a body o_f mercury vfor
~localized point of heat generation in order that bridging said shell and electrode about the inner
overheating of any particularportion of the end of said sleeve upon tilting of said switch.
cool portion of the switch.
switch will be prevented. It is apparent,- how
ever, that this ratio or relationshipbetween thesetwo factors may be varied, depending upon the
_type of switch which is employed, the currentV
which it is required to control, vand other similar
factors which must be considered. Therefore,
while we have disclosed a particular ratio of ap
proximately 3% of liquid 'fill inI the vapor space,
we do not intend to limit the invention to ex
actly this particular percentage, since it is ob
vious that the >proportions can be regulated or
3. A switch of the metallic envelope type com 40
prising a tubular cup-shaped metallic shell hav
ing an enlarged open end, a ceramic insert clos
ing thevopen end of said shell, a rubber gasket
compressed between the external annular sur
face of said insert and the inner surface of the ,
open end of said shell, an integral sleeve extend
ing longitudinally from said insert into said
shell, an electrode within said sleeve Iextending
to a point adjacent the open end thereof, a stud 50
varied as desired to meet certain specified con- . securing said electrode in said sleeve and ex
tending outwardly through said insert, a rubber
One primary concept vinvolved in this phase of
the present disclosure is to reduce _the amount of
liquid fill to the point that when the entire liquid
ñll is vaporized the pressure of the vapor will
then not exceed the strength of the shell or con
tainer of the switch. 'I'his medium, i. e., a con
densing vapor, is a highly eiiicient means for
transferring heat. .'I'he parts are so proportioned
that on rated maximum duty the liquid will not
all be vaporized, but> suiiicient vaporization oc
curs to carry off the necessary amount of lieat
to keep the temperature Within safe limits. If
rated maximum is exceededy the pressure may
rise, but never to the point of breaking orde
stroying the container.
gasket about said stud and compressed -radially
against said insert, insulating ñange means on
said insert surrounding said stud axially out 55
wardly of the-end of said shell, a body of mer
cury for bridging said shell and electrode, and
means for making and breaking contact between
said shell and electrode over the open end «of
>fi. A mercury switch of lthe closed metallic en
velope type> comprising a liquid fill consisting of
an anhydrous alkaline liquid of low vapor pres
sure and having a substantially constant vis 85
cosity within the temperature range‘to which it
is subject and being inert with respect to'the '
mercury in-said switch, said liquid rlll compris
We donot intend to be limited to the speciñc" ing`
approximately 3% of the volume of the
details shown and-described, nor to the propor
switch envelope.
tions or sizes shown, as mòdiñcations of our in
ventiony will be obvious to'thosef skilled in the art.
We claim:
1. In combination, in a switch of the class de
scribed, a cup-shaped metal shell having an en
5. In a mercury switch having a switch en
velope, _an anhydro
alkaline liquid ñll therein
above the mercury i said envelope, the volume
of said ñll being such that complete vaporizatio /
thereof will not produce a pressure/sumcieí to 75
rupture said envelope and associated parts of
said switch.
6. In a mercury switch, a metallic cup-shaped
shell, a ceramic insert in the open end thereof,
lcompressible’gasket means between said shell
vand insert, an electrode carried on the inner
surface of said insert and having an outwardly
extending shank, gasket means about said shank
and compressible against said insert, a- body of
mercury in said shell of such quantity that the
meniscus height thereof is substantially equal to
the radial distance between the inher surface of
said shell and the peripheral surface of saidl elec
trode, and a vaporizingpartial liquid iill in said
15 shell for dissipating heat therein during rapid
operation of said switch, said gasket means be
of substantially not more than a ñlm in contact
with the mercury at the point of greatest heat
generation, said film being locally vaporized andl
the vapor carrying the heat to the envelope to
equalize the same.
11.'In a heavy duty mercury switch of the
metal-envelope type comprising a metal shell
and an insulated electrode sealed together and
insulated from each other, a body of substantially
pure mercury for making and breaking connec 10
tion between the shell and the electrode, said
shell being beaded over the insulation of the
electrode to provide a closed envelope capable
of withstanding high internal pressures and tem
peratures substantially in excess of boiling water, 15
and a small quantity of anhydrous _triethanol
ing so shaped as- to relieve excessive internal
amine forming a iilm of liquid in contact‘with
pressures in said shell but preventing entrance
the mercury and being vaporized locally by the
heat of the current to transfer heat from the
r `
point of vaporization to cooler parts of the en 20
shell, an insulator, and an electrode deñning an, velope, where it is condensed.
12. 'Ina mercury switch, a metallic cup-shaped
envelope which consists chieñy in 'a metal heat
conducting wall and which is of great strength shell, an insert closingone end of said shell, a
to resist internal pressure, a body of substantially body of mercury in said shell, an electrode car
ried at the inner end- of_said insert and radially 25
pure mercury adapted to make and to break con
tact between the metal shell and the electrode, spaced from said shell a distance substantiallyv
and a thin film of a viscous anhydrous alkaline equal to the meniscus height of said mercury,
liquid of high boiling point which is in contact said insert having an annular recess in the radial
with the mercury and which is vaporized at the inner face thereof about said electrode of a curva
of heat generationv and condensed upon ture corresponding to the curvature of the ap 30
so. point
the metal walls of the envelope to dissipate heat proaching edge of said mercury, and a shank
and equalize the temperature of the parts of on said electrode extending outwardly through
the switch, the amount of liquid in saidenvelope said insert. .
-13. In a mercury switch, a ceramic cup-shaped'
being so ‘low-that excessive pressure is avoided
by vaporization of the liquid as fast as it flows envelope having an open end and having an en
larged annular wall portion about said end, an
to the point of heat generation.
8. In a mercury switch of the sealed envelope electrode sealed in the opposite end of said en
velope, a second tubular sleeve electrodev ex
type having iron electrodes and a body of sub
tending into the open end of said envelope and
stantially pure mercury for making andV4 break
ing circuit betweenl the electrodes, a limited fill _terminating within said envelope iat a point
of triethanolamine providing not substantially spaced from said electrode, a retaining flange
of air thereinto.
more than a thin film which is adapted to be
> vaporized locally by the action of makingl or
breaking the circuit, the vapor thereof engaging
the walls and there being condensed.
9. In a mercury switch, a tubular ferrous en
for said second electrode embracing the enlarged
wall portion of said envelope, and resilient seal
ing means compressed between said flange and
said enlarged wall portion.
14. In combination, a pair of cup-shaped mem
velope, a plug of insulation closing said envelope, bers disposed in telescoping relation- with the
the end of said envelope >beingl beaded over a open ends thereof in overlapped relation to form@v
portion of the plug -«'“to retain said plug- -against aA switch envelope, annular sealing means sur-i
internal pressure, a central electrode extending rounding an end-of one of said members', means 50
50 -through and sealed to said plug and _having a carried by the other member for radially com
head upon the inside thereof preventing the ex pressing said sealing means into sealing engage
pulsion of the electrode by internal pressure, a ment to form a sealed switch chamber, a body
of mercury in said chamber,- one of said mem
body of substantially pure mercury in the en
for connecting and disconnecting the shell bers being> metallic and the other being formed of 55
sa A velope
and electrode, and a small quantity only of refractory insulating material, and an electrode
ethanolamine in said envelope and in contact carried within said chamber by said insulating
member and spaced from the other member; said
with the mercury, said ethanolamine being pres
ent -in less than 5% of the free internal volume mercury bridging between said electrode and said
other member upon tilting of the switch chamber. 60
of the envelope and being capable of being va
15. In combination, a cup-shaped ceramic
porized locally by operation of said switch under
member, a cup-shaped metallic member fitting
load in making and breaking the- circuit.
into and- extending toward the closed end of
10. In a mercury switch, a tubular ferrous en
' velope, a plug of insulation closing said envelope, said ceramic member, electrode means carried
within the closed end of said ceramic member, 65
65 the end of said envelope being beaded over a por
an insulating ring within said ceramic member
tion of the plug to retain said plug against in
ternal pressure, a central electrode extending between >¢said electrode means and the inner end
1 through and sealed to said plug and having a vof said metallic member forming ~an inclined
raceway therebetween, and ñuid conducting
head upon »the inside thereof preventing the ex
pulsion'of the electrode by internal pressure, a means for eiîecting connection between said 70
body of substantially pure mercury in the en-_ metallic Amember and said electrode means over
velope for connecting and disconnecting the shell said raceway upon tilting of said switch.
16.7In combination, an elongated cup-shaped
and electrode, and a small quantity of an anhy
-drous alkaline liquid of a boiling point in excess ceramic member having an open end, a -tubular
75 of that of water, said liquid forming a thin layer electrode sleeve sealed in the open end ofwsaid/
member, electrode means carried within said
type, a cup-shaped metal shell forming one elec
‘ member at the closed end thereof and spaced
trode and having an enlarged open end, a re
from the inner ende ef saidi electrode sleeve by
an annular wall portion of Ysaid ceramic mem
ber, and a body of mercury in contact with said
electrode sleeve and movable into contact with
fractory insert in said open end having an axially .
tapered- bore opening into the interior of said
envelope, Yan annular resilient gasket interposed
between the external annular surface of said in
said electrode means upon tilting of said ceramic - sert and the adjacent internal surface of the en
larged end of said` shell, said shell having its de
i’ining edge forced radially inwardly to eifect ra
dial and axial compression of said gasket, an
electrode carried within said bore and having its
periphery spacedzfrom the annular defining sur
face of the smali end of-said bere, a body of
-. 1f?. In a metallic envelope mercuryVV switch hav
10 ing two vbodies of mercury adapted to makeand
break contact over an'insulating surface by rela
tive movement therebetween, a film of an anhy
drous alkaline liquid' over said bodies of mercury,
said ñlm serving toi maintain maximum surface
mercury retained in said bore in contact Ywith a .
compressed therebetween upon relative movement
portion of the face and periphery of said elec
trode, and a second body of mercury in said shell
adapted to makeY and break contact with said
of Leaid mercury and to assist its; move
is `tension
ment. the films on said`bodies of‘mercury being
toward each other to increase the head of mer
ñrst body of mercury at a. point spaced from said _
cury at the-contacting surfaces, andethe potential
across s_aid bodies of mercurypuncturing said
ñlm to produce instantaneous enlarged surface
contact between said bodies for reducing the re
ing a substantially cup-shaped switch chamber
22. In a metallic envelope mercury switch hav 20
defined by metaliic walls and closed at one end by
, sistance to passage of current through said con
a refractpry ceramic insulator carrying a metallici
electrode, said chamber having a liquid cgntactorY
_ 18. In surfaces.
a mercury switch, a cup-shaped metallic '
25 tacting
envelope having an lenlarged open end, a ceramic
insert in said open end having an external an
nular shoulder, resilient sealing means between
-sald enlarged vend of Ysaid envelope and saidV
movable upon tilting of said switch to make and .25
break contact between said envelope and said
electrode, the method of maintaining the switch
cool during operation at its rated capacity which
comprises providing a limited flll of an anhydrous
shoulder, said enlargedend having its defining
alkaline liquid which clings to and-moves with 80
edge pressed radially inwardly axially outwardly _ said contacter, eand has .a boiling point below
of said shoulder to lock _said insert in sealed'posi
the temperature vto which flow -oi! normal rated '
tion therein, said ¿insert having a tubular'` sleeve current-¿tends to heat said conductor, vaporizingVV
extendingaxiallyï’iinto Vsaid envelope in spaced ' said liquid fill at vthe point of said contact bei
relation thereto, a tubular electrode within said tween .said envelope and said- electrode by the
sleeve terminating adjacent the inner endthereof
and having a shank portion vextending outwardly
through said insert, anda body Y'of mercury in
saidenvelope for bridging between said electrode
and envelope and makingV and breaking contac ~
over the defining edge of ?said sleeve.
19. Means for dissipating heatv from the*A point
of generation thereof in a sealed metallic en
velope mercury switch having a ceramic insert
heat generated in said contacter, providing un
restricted movement of said vapor into contact
with said metallic walis to dissipate said heat
therefrom and to condense said vapor, and pro
viding for freeë return of said condensate into
contact with said contactor.
v 23. A. switch comprising a first cup-shapedr
_member having a central axially projecting tubuê
lar portionv secured to the base thereofi and de
45 in one er?el thereof Vcarrying an electrode and hav
y ing a body of mercury therein adapted to make
flning therewith an annular groove, a second 45
and break contact betweengsaid envelope and
electrode’Y over an internal surface of said‘insert,
comprising an anhydrous alkaline -liquidi-lll of"
50 small volume compared to the internal volume of
-said switch and adapted ¿to ‘adhere to the mer
cury, said ñll having a?relatively high boiling
in said groove, an electrode carried at the closed
point whereby upon arcing at said surface saidl
cup-shapedV member having its open ,end sealed
end of ~said second member, and iiuid contact
ing means for bridging between saidl electrode
and said tubular portion upon tilting o1' said 50»
24. _A ceramic insert for a mercury switch coni;
prisinga cylindrical portion andan enlarged head , i
fill vaporizes and'passes to cooler portions of said ë portion having a tapered external surface cori
55 `'Witch where it is condensed and flows by gravityS verging toward the cylindrical portion, said in 55
back to the point of heat generation. Í
- _
sert having imperforate sidewalls and having
20. Means forfdissipating heat from the point a conical tapered runway terminating in a sharp
of generation thereof in a sealed metallic envelope Y
mercury switch having a ceramic (insert in one
60 end thereof carrying anî electrode `and having a
body of mercury therein adapted to make and
peripheral edge defined by a radially extending
-groove terminating theÈ conical runway.
' 25. In combination in a mercury switch, a
bushing of reîractorylfinsulation having imper
break contact between said envelope and elecf forate side walls and having a peripheral shoul- Y '
trode over an internal surface ofsaid insert, com- ’ der deñning aY wall of a mercury retaining pocket
prisingr an anhydrous alkaline liquid fill of smalilf
volume âcompared to the internal volume of said* and a bore extending in one direction'from said 65
switch 'and adapted to. adhere to the mercury, shoulder and forming a runway for mercury, said
¿said fill: having a relatively high boiling point? bushing having a substantiaiiy cylindrical por-v
-whereby upon `arcing at said ïsurface ?said ñll tion extending in the apposite direction from said
vaporize’s and passes' to cooler portions of said .shoulder to form a part of said mercury retain
70 switch whereit is condensed and flows by gravity ing pocket, alrtubular metal shell having Ian en->
larged sealingportion having spaced inwardly
back to the point of heat generation, said vapori
zation producing an increased pressure in said extending shoulders for holding the bushing
switch tending to minimize arcing during making l against endwise displacement in either direction
and breaking of contact.
è relative to the shell, and a resilient annular body ’
21. In a mercury switch of the heavy duty
of insulation disposed between the shell and saidv
bushing and being held in compression uponv the
external peripheral wail of the bushing whereby
¿i the bushing is also placed under compression.
26. The combination of claim 25 with an elec¿5 trede carried by the bushing, said electrode hav-
bushing, a resilient deformable sealing b?hing
surrounding said stem within said refractory
bushing, and ineens for holding said sealing bush
ing in compression to seal the electrode tothe re
Iractory bushing.
ing a disc-shaped portion closing~ of! said cylin-
drical portion and forming a wall of said pocket
and having a stem portion extending outside said
Patentl No. 2,152,920.
october 11, 1958.
It is hereby certified that error appears in the printed. specifi-cation
of the above numbered patent requiring correction‘as follows z Page 6 , second
column, line 27 , claim 2, for the word "exterior" >read interior; and that
’ the said Letters Patent should be read with this correction thereinrthat
the same may conform to.the record ofthe case in' the Patent Office.
_ ‘Signed and. sealed' this 29th day of November, A. D. 1958;
Henry Van Arsdal e
Acting` Commissioner of Í’dtents.
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