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Патент USA US2132921

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Oct. 11, 1938.
Filed Dec. 6,’ 1935
3 Sheets-Sheet 1
.Z'nz/én $0219:
Wm M
. #2192791
Oct. 11, 1938.
P. s. BEAR
Filed Dec. 6, 1955
5 Sneets-Shéet 5
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Patented Oct. 11, 1938
Paul S. Bear, Elkhart, Ind., assignor, by mesne
assignments, to Bucklen-Bear Laboratories,
‘Inc., Elkhart, had, a corporation of Indiana
Application December 6, 1935, Serial No. 53,146
29 Claims. (Cl- 200—152) ‘
This invention relates 'to mercury switches and
the like.
The present application is a continuation in
part of the co-pending application of Herbert
5 E. Bucklen and myself, Serial No. 665,654, ?led
April 12, 1933, and my ‘copending application
Serial No. 745,842 ?led-September 28, 1934.
While I have elected to illustrate my invention
in a switch of the metalvshell type, there are
certain features of my invention which are not
limited to this particular type. Also, while the
preferred embodiment herein disclosed is a grav
ity-operated switch, the invention is not limited
to that particular mode of operation.
The gravityeoperated ‘switch, particularly of
the mercury type, has long been known. It is
attractive in theory because of the theoretical
ability to enclose the contacts and the traveling
conductor (mercury) in a complete enclosure,
20 where, theoretically, the conditions of operation
are maintained even though the exterior be sub
jected to adverse conditions.
Practical attain
ments fall far short of the ideal, as those skilled
. in the art well know.
With the theoretically ideal conditions which
appear to be possible, such a switch should be
capable of an inde?nitely long life, i. e. capable
I of ' operating perfectly for an inde?nitely great
number of operations for antinde?nitely long,
30 time.
Practice falls far short of this ideal, as
those skilled in the art well know.
Also, theoretically, there should be no limit
‘to the current-carrying ability of such a switch.
Again,_ practice falls far short of the ideal.
Another attractive featureof the enclosed mer
cury switch is that the making and breaking of
the circuit occurs within a complete enclosure,
so that the switch, theoretically, is safe to use
where, an open spark or are would be dangerous
words I teach herein howv to make a switch sub
stantially non-deteriorating from age or use.
One of the speci?c objects of the invention is
to increase the capacity or duty of enclosed mer
cury switches. By my invention, a marked in- 5 '
crease in current carrying ability of switches is
made possible. Also by my invention, a marked
increase in the amount of current that can be
made and broken is made possible.
_ ‘Another object of my invention is to increase 10
the life of a switch of the present type. By my,
invention, more operations of making and break
ing a given current are made possible.
Another object of this invention is to improve
the repeat performance of switches of the‘ present 15
type. By my invention the uniformity of opera
tion of switches of this class is greatly enhanced.‘
My invention makes possible more accurate con
trol of the exact’ instant that circuit is made or
broken and likewise of the exact angular position 20
at which. contact will be made or broken.
Another object of my invention is .to eliminate
irregular making and breaking or “stuttering"
of switches of this class. By my invention the
sharpness of make and break is improved and 25
. made permanent.
.A'further object of the present invention is to
decrease the cost of switches. By my invention,
the initial cost of a switch of a speci?ed capacity
is low and the life is long as compared to prior 30
switches. As a result, the overall cost to the
consumer is greatly reduced. -
Another object of the present invention is to
provide a switch of greater strength and rugged
ness, both from the standpoint of external in
jury and from destruction by internal operations.
In the switch of my invention, the exposed parts
are chie?y strong, metallic parts. The only exposed insulation is a tough, strong piece of ~?brous
insulation or the like. The switch is not injured 40
40 because of combustible or explosive materials in
in shipping, even though the amount of mercury
far short of theory, as it is’ not at all-unusual
for switches of the prior art to explode in opera
be large and the handling rough.v This saves both
in loss in the factory and ‘in transit, and lowers
proximity to the switch. Here, also, practice falls
tion and thereby, instead of providing a protec
tion, actually constituting a hazard as is known
to those skilled in the art.
The general object of the present invention is
to produce a mercury switch of the enclosed type
which will be superior in structure and perform
ance to known switches.
the cost of packing materially.
A further object is to provide a switch of 45
greater safety. By the use 015_ my invention,
much greater internal pressures are permissible
than with switches of the prior art. The switch
of my invention will yield under pressure in a
de?nite manner only. and hence is much safer 50
An important aspect of the present invention for the operator or attendant as well as for the
is the selection, preparation and coordination of adjacent machinery and materials.
A further object of my invention is the provi
materials and parts to render the working parts
of switch stable chemically, mechanically and sion of a switch which is capable of short time .
electrically even under severe duty. In other overload demands far in excess of what can be 55'
, ‘2,132,921
withstood by switches of the _ prior-7 art. My
switch will stand temporary overloads or a tem
porary. schedule of operations above normal with-'
out injury, which switches of the prior art could
not endure.
among which arez-freedom from a dry surface
_ ?lm which interferes with making contact with
the‘ ?xed electrodes and with making mercury to
mercury contact; high surface tension, ‘ winch
allows maximum height of the meniscus and
A further object of the present invention is to ' therefore greater cross-section of mercury when
provide‘ a switch of few simple rugged parts, the mercnry to mercury contact is formed; high con
assembly cost of which is low and readily capable
of being performed by hand or automatic ma-=
ductivity; and long life without change of the
above characteristics, even though subjected to
A further object of my invention is the provi
sion of improved suppcrting and sealing means
for the ceramic and the rear or insulated elec
' heavy duty and high temperature. As an insur—
ance of the initial purity‘ of thelmercury I pro
vide a fractional ?ll of anhydrous triethanola
mine which covers the surface of the mercury at
1.0 chinery.
. .trode.
A further object of my invention is the provi
sion of improved closure means for the open end
of the shell.
‘all times. If desired, an atmosphere of hydrogen
may be provided above the liquid, but this is not 15
essential. A vapor ?ll of triethanolamine is en
tirely satisfactory, since the triethanolamine ap
The switch of the present invention makes posé , pears to provide the necessary chemical protec
sible the employment of switches of the enclosed tion against ?lming, oxidation, or acid forming
20 mercury contactor type in ?elds and for services within the switch. it appears to unite with any 20
now closed to such switches because of their limi
free oxygen within the casing and thus protect
tation as now constructed.
the mercury from oxidation or‘ any other deteri
Now, in order to acquaint those ‘skilled in the oration in use.
art with the manner of constructing and operat-.,
Another important advantage attained by my
25 ing a speci?c iorm of the invention, I shall de _ present switch is the provision of a tough, elec 25
‘scribe in detail an embodiment thereof in the trically puncturable, mobile liquid ?lm that is
following speci?cation in conjunction with the present-over the interior surfaces of the switch
accompanying drawings.
I have provided _a switch in which the making
and breaking of contact is effected over the ce
ramic surface which spaces the two electrodes
envelope and over the mercury contactor. I have
found that an anhydrous alkaline ?lm is most
suitable for this purpose, since the alkalinity pre 30
serves the full surface tension of the mercury
apart. In this connection, I avoid any possibility - whereby the body of mercury will always stand
of pitting or, oxidizing of the adjacent metallic at its full meniscus height, approximately 3 milli
surfaces of the electrodes by providing for mer
meters, and‘ will not ?atten out, as is the case
35 cury-to-merciiry making and breaking of con .when in the presence of an acid. The ?lm acts as 35
tact between the electrodes.
- a lubricant for assisting movement of the mere
Ancther characteristic of my present switch cury- Further, the anhydrous characteristics of
which» materially improves its operating charac
the ?lm preserve the metal surfaces and mercury
teristics and accuracy of operation is the provi
against oxidation caused by moisture within the
40 sion of a construction wherein a stable body of ‘switch envelope, and against the deleterious ef 40
mercury‘ is retained in position adjacent said fects of any occluded gases. However, the ?lm is
sharp cutting edge and in contact with one of the most effective in assisting the operation of the
switch electrodes I have found that a certain switch by reason of its e?ect during making and‘
critical size of mercury globule is capable of re- ‘ breaking of the circuit between the two iaodies
45 taining individual stability throughout the entire
of mercury. The ?lm’covering the stationary or
working angie of operation of the switch. The stable body of mercury,- upon approach of the
length of the body of mercury that will have in
moving body,.merges with the ?lm' covering the
herent stability I have found to be of the order of moving body. This ?lm thereby extends between
twice the length of a meniscus curve, that is, con
the two'b'odies of mercury, and retards their ap
50 sidering a body of mercury having curved meniscii proach into contactgbuilding'up the cross-sec 50'
at opposite ends, the stability is determined by tional area of mercury at the contacting surface
these ends, since the intermediate ‘portion of the
mercury .gives no stability.’ The length of a
meniscus curve I de?ne as the longitudinal dis
55 tance from the point of curvature of the meniaus
by this resistance. Then, as the mass or inertia
of the moving body of mercury increases the pres
sure on the ?lm, tending to squeeze the ?hn out
from between the two bodies, the eiectrical poten 55
tial suddenly punctures the ?lm, and the mercury _
rushes into contacting engagement along a con
tact area that is considerably increased over the
length equal to twice this distance, _I retain the‘ res. that would normally be present. This pre
60 stabilizing characteristics of the meniscii-whiie at vents sputtering er frying of the contacting faces 60
the same time eliminating the unstable portions. ~ of the mercury and insures a sudden and complete
downwardly from the top surface of the mercury
_ to a plane tangent tn the. endof the body of the
mercury. By making the body of mercury ef a
Although stability will be retained with a body of
mercury of iess length, it will not give the desired
electrical conductivity for heavy loads, since‘ the
65 cross-sectional'area of mercury available for cur
rent carrying purposes will be smaller than is de
sirable. I have found the desired length for sta
bility to be not, more than 37;.
By initial puri?cation of the mercury in accord
ance with the method disclosed and claimed in my
copending application,‘ Serial No. 67,816,’ ?led 7
closure c-f contact through a relatively thick
section of mercury capabieof carrying the cur
rent with, a
resistance. The ?lm is'
su?iciently volatile so that a portion thereof va 65
porizes upon contact and dissipates heat readily _
- to all parts'of the switch. The vaporization also
effects a continuous purging of all internal sur
faces of the switch, and serves to prevent notation _
of scum or foreign particles on the adjacent con 70
, tacting portions of mercury.
March 9, 1936, I provide mercury which is ' Another advantage of this ?lm empioyed in
1 freed of injurious impurities to an extent not . combination with a stable body of mercury which
heretofore attained in the art. This mercury so stands above the sharp cutting edge is that it
75 puri?ed has a number of desirable characteristics. prevents arcing across this edge, thus preserving 75
‘the ceramic or refractory material forming the
spillway and cutting edge. The high meniscus
of contact of a mercury switch of the prior art;
and the presence of the liquid cooperate in the
protection of this edge.
Figure 14 is a diagram of the switch of Figure
13 breaking circuit;
Figure 15 is a longitudinal section of a modi?ed '
form of switch;
Figure 16 is a cross-section taken on line l6--l6
arating bodies of mercury upon breaking of con- ,
Figure 15;
tact therebetween, and acts as an arc extinguish
Figure 17 is a longitudinal section of a low
er for preventing drawing of an arc between the
relatively moving bodies as they snap away from angle modi?ed type of switch;
Figure 18 is a cross-section taken on line |8-l8 10
each other due to surface tension.
Figure 17 ; and
Prior types of switches employing mercury con
Figures 19 and 20, respectively, are fragmen
tactors have attempted to use alcohol as a liquid
?ll. However, alcohols and similar compounds of tary sectional views‘ showing two modi?cations
of the inner electrode of the switch of Figure 1'7.
this class cause mercury to separate into'?ne glob
Referring now in more detail to the drawings,
disadvantages arise with the use of oils, kerosene in Figure 1 I have disclosed a switch comprising
and the like. This is also true with water to a a drawn metal shell 5, forming the main portion
marked degree, althoughv I have‘ found that of the switch envelope. The shell may be formed
the addition of a slight amount of ammonia will of substantially pure iron, stainless steel, or other 20
ferrous material whichis not attacked by mer
20 overcome this characteristic by rendering the cury. The open end of the shell 5 receives the in
?ll alkaline. When mercury has been shaken up wardly extending ?ange 6 or a ceramic spacing
in contact with oils or the like it separates into member ‘I, which at its opposite end is provided
?ne globules and tends to remain in such condi
tion over long periods of time and di?lculty is with the ?ange 8 receiving the second electrode
shell or cap 9. This ceramic is preferably porce
25 encountered in getting them to reunite, usually lain. It may be wet process porcelain, isolantite,
necessitating centrifugal force or a solvent to or other, refractory insulation. If wet process
remove the oil or kerosene.
is used no glazing is necessary.
The high viscosity oftriethanolamine allows porcelain
the ?anges 6 and 8 the ceramic
the mercury to break up into globules, but they ‘I Intermediate
is provided with an axially extending tapered 30
bore III, which bore, at its small'end, is termi
due to the alkalinity of the ?lm. Such action is nated
by the ‘radially extending wall I2. The
ideal for mercury'switches, because if the mer ‘ bore II) is smooth. The dihedral or solid included
cury becomes broken up by jarring or . rough
is less than 90°. The corner 22 is sharp.
handling, the main body and the retained body angle
The shells 5 and 9 may be secured to the ceramic
35 will ‘have returned to their proper shapes in the ‘l in any suitable manner, as by cement, threads,
time required to mount the switch in a clip and v or in the manner disclosed in the previously
connect the conductors to an external circuit.
copending applications. The shells
Other objects and advantages of the present mentioned
5 and 9 may have ?anges welded thereto, and
construction willbe explained in conjunction with these ?anges clamped or beaded together in in
the following detailed description of my switch sulated relation. ‘Ears may be attached to the
which, taken in conjunction with the accom
shells and these cars held together by screws,
panying drawings, will disclose to those skilled rivets or the like, suitably insulated. The par
in the art the particular construction and opera
ticular manner of securing these members 5 and
tion of a preferred form of the present invention. 9 together in this embodiment may be widely
In the drawings:
vvaried within my invention. The shell 5 is pro
Figure l is a ‘sectional view through one form .vided
with a contact lug l3 suitably secured there
of the switch;
to at one end and receiving the conductor [4 at
Figure 2 is a transverse sectional view» taken the other end for connecting the shell to one
substantially on line 2--2 of Figure 1;
side of the circuit controlled by the switch. The
50%‘ Figure 3 is a sectional view of the switch of shell 9 is similarly provided with a lug l5 receiv
igure 1 with the application of an enclosing seal
ing the conductor 16 connected to the other side
the circuit.
Figure 4 is a transverse sectional view taken Vof The
housing is assembled and mechanically se
The ?lm also forms immediately over the sep
on line 4-4 of Figures;
Figure 5 is a view similar to Figure 3, showing
the switch in closed position;
Figure 6 is a diagrammatic view of a modi?ed
type of switch;
Figure 7 shows the switch of Figure 6 in
switch-closed position;
Figure 8 is a partial diagrammatic enlarged
view of the bodies of mercury at the instant prior
to contact;
Figure 9 is a diagrammatic illustration of the
determination of a stable body of mercury;
Figure 10 is a diagram illustrating the tend
ency of the two bodies of mercury to pile up ver
tically before breaking the intervening film and
Figure 11 is a similar diagram illustrating the
70 condition of the mercury at the instant of merg
ing the two bodies;
Figure 12-isa longitudinal sectional view of a
' commercial embodiment of our invention;
Figure 13 is a diagram illustrating the making
cured together, leaving only the ?lling opening
in boss 20.v
Su?ice it to say that I clean the inside surface
with triethanolamine before evacuation. Evacu
ation to remove oxygen is then carried to a fairly
high value. The interior may be washed with
hydrogen and again evacuated. ‘After ?nal
evacuation the desired amount of cleaned mer
cury is introdubed. Thereafter the desired
amount of liquid?ll is introduced, by a following
atmosphere of hydrogen or a hydrocarbon gas or 65
the like, and the envelope is sealed off.
The mercury employed in my switch is especi
ally-prepared for the service which it must per
form, by<the method disclosed and claimed in
my copending application, Serial No. 67,816 ?led
March 9, 1936; . Su?ice it to say that I charge a
relatively large amount of distilled, cleaned, and
neutralized mercury, (for example, 30 cc.) into
a closed chamber which is in reality a large mer
cury switch. That is to say, it comprises an iron 75
- shell electrically divided by a refractory-insulator . its stability due to the cohesion effect provided
like the structure shown in Figure 1. A charge by the surface tension at the de?ning edge of the
of triethanolamine su?icient to wash the inside - body, of mercury. In Figure 9 I have disclosed,
a body of mercury 25 lying on a ?at surface
26, and it will be noted that the end portions
large switcli. Then the large switch or treat
thereof assume de?nite meniscus curves indi
ing device is operated to make and break a rela
cated vat 21 and 28. The length of such a
tively heavy current. The agitation and wash
meniscus curve is considered to be the distance
ing in the presence of hydrogen and the electric from the point at which the curve initially starts
arc, together with the heating entailed by the from the top planar surface of the body of mer
._ passage of current, imparts certain characteris
cury, to a plane extending tangent to the end of
tics to the merucy which are of great importance the mercury, this distance being indicated by
in the performance of the switch.
a in Figure 9. The portion of mercury between '
of the shell and the mercury, and an atmosphere
of hydrogen, are introduced into the shell or
First, the mercury so treated has a very posi
tive and high meniscus. This isimportant in
several respects, namely, ?rst, in ‘the increased
cross-section of mercury to mercury contact in
making qircuit, second, the' greater snap in break
ing circuit, and third, the higher the meniscus
the less angle required to cause it to travel on
_ va supporting surface.
Second, the treated mercury appears to have a
skin that protects it from oxidation, even if ex
posed for some time to atmosphere. This skin
appears to be a thin ?lm of' triethanolamine.
This ?lm lubricates the mercury and, makes
gravity travel easier, also-lowering the angle re
quired to cause it to travel.
Third, the switch containing mercury so
30 treated runs cooler on a test run than will a like
switch with the mercury cleaned only as known
by the prior art.
Fourth, the interior of the. switch remains
cleaner and operation is sharper and at a lower
angle, both because of the permanent character
of the cleaned parts and for the reasons above
Fifth, the life of the switch on destructive tests,
using mercury cleaned as per my method, is
vastly increased.
these end portions, indicated at b in Figure 9,
is unstable, and is not subjected to the cohesion 15
effect which imparts stability to the end portions
21 and 28.
By thus eliminating the portion of mercury
within the space b, I provide a stableglobule
of- mercury comprising the portions 21 and 2,8‘ 20
which are joined to form a. globule that pos
sesses inherent stability in all operating positions of the switch. I have found that by dis
posing two vertical end walls a distance apart .
equal to- 2a in Figure 9, the entire top surface 25
of the included body of mercury, nomatter how
deep, will provide the maximum height of menis
cus above the points of end tangency, i. e., con
tact with the vertical end walls, and a high
degree ‘of stability for any required motion or 30
inclination utilized in operating the switch. This
is of great importance in securing the desired
uniformity of response which is termed ‘.‘repeat
performance". The body of mercury I8 is pref
erably held in this manner, the spacing between 35
the radial wall l2 and the end portion 23 of the
shell 9 being such as ‘to produce a globule of
mercury which is of the order of the length ,of
two meniscus curves, which is approximately
equivalent to a’; of an inch.
‘ .
The amount of mercury employed in my switch
While I have shown in Figures 1 to 5 the length
is proportioned to be ample to form the desired of the body of mercury was greater than the
conducting link between, shells 5 and 9. In a" ' dimension stated, these drawings are not to scale
.35 ampere switch‘I employ about 6 cc. of mer
and are illustrative only. Figures 6 to 9 and 12
cury. The liquid ?ll in that size switch is about are approximately to scale-in this respect, and
1/2 cc. of triethanolamine. The shells 5 and 9 »
illustrate more nearly the dimensions of. the
, and the ceramic ‘I are sov porportioned as to give
stable body of ‘mercury.
the desired cross-section of mercury for [conduc
This globule of mercury l8 possesses an inher
tivity. The shell 5 retains, back of shoulder l2, ent stability throughouttherange of operating
50 a sufiicient body of mercury to provide adequate
inclination of the switch,.s,uch that it does not
contact conductivity with the shell and to pro
tend to run down the spillway surface‘ [0, ‘nor 50
‘ vide a substantially stable body of mercury back does it overhang this spillway surface upon
of shoulder 22 standing at maximum meniscus breaking of the circuit between the bodies of
height. The shell 5 should be long enough to mercury
I‘! and III. In the normal open position
provide the free runway room to let the parted
body of mercury travel endwise without piling up. of the switch, the body of mercury l8 stands 65
By the provision of the radially extending wall - meniscus high above the de?ning shoulder 22,
l2, there is provided an acute angle shoulder or producing a globule of mercury which has a_
relatively large surface available for contact by
edge, indicated at '22 between the tapered pas
the approaching edge of the body of mercury
60 sageway l0 and‘thewall [2, which prcvidesa
I‘! when the'switch is moved toward switch closed
sharp._cutting edge over which the mercury isv position.
parted for breaking of contact, and over which
the mercury contacts during contacting engage
By‘suitable spacing of the end wall portion 23
of the shell 9 with respect to this radially ex
tending ,wall l2 of the ceramic 1, I provide for
introducing a. stable body of mercury into the
bottom part of annular recess de?ned by the wall
70 l2 and the end wall portion 23 of the shell 9.
shoulder 22, with the tapered spillway l0 extend
ing‘directly from this edge downwardly to the
other electrode, I produce a. switch, which has
the decidedly'advantageous feature of "repeat
performance". ‘By this I mean that the switch,
opens the circuit at a certain angle of inclina- I
tion during successive switch opening movements,
likewise closes the circuit at a certain pre
This stable body of mercury‘should, formoptimum and
determined angle of inclination during successive
conditions, be of the order of the length of two
mercury, which curves are
.determined as illustrated in Figure 9.
75 I have found that a body of mercury retains
- vmeniscus curves of
switch'closing movement, even under‘ wide vari
ation or the rate of tilting.
This insures that _
any control circuit connected ‘to the switch will
be operated at the same point or angular posi 75
tion of the switch at all times, and, conse - the shelf formed by surface E. Then, as further
quently, a switch which is adapted to cut in tilting occurs, this small body of mercury may
a circuit at a predetermined point will always run o?! the shelf and in doing so may momen
out in the circuit at this same point, depending tarily reestablish the circuit, causing mis-opera
upon the differential range covered with respect tion. If the motion of tilting is more rapid, the 5
to the operating angle of the switch. By the rupture of the mercury may occur further back
provision of the sloping surface extending di
than ridge E. There is no de?nite predictable
rectly from the shoulder at 22 downwardly into action. Hence, when the circuit is again to be
the other electrode, the weight of the overhanging established, the angular position at which the
10 portion of mercury as the switch moves toward two bodies of mercury meet is not accurately 10
open switch position insures that severance of de?nable, as it will vary.
the two bodies of mercury will occur at this shoul
Figure 13 shows the di?iculty encountered in
der, which is the point of smallest cross-sectional closing circuit under these conditions. If the
area, thus insuring that the globule of mercury advancing body of mercury H is caused to move
15, 18 will remain the same after each successive
switch opening operation. This is also e?ected
by reason of the inherent stability of this globule
of mercury as determined by the spacing between
the radial wall I! andthe end wall 23 of the
20 shell 9.
Thus, a switch constructed in this manner is
capable of producing repeat operation at the same
angle of inclination, whether'tiltlng be rapid or
very slow, and in which the circuit closing and
circuit opening contacts are all made at a cer
tain predetermined point in the switch, with
no possibility of overhang or sputtering, and no
possibility of additional small particles of mer
cury running down the inclined surface due to
‘so breaking of the circuit somewhere along this
surface, which might cause a ?ickering opera
tion. This, in effect, produces a switch‘ which
has a very positive and reliable action, and is
accurate in operation with respect to predeter
35 mined response to either temperature, humidity,
or other conditions, or for use with mechanical
or electro-mechanical movements of calibrated
instruments -and the like.
For accurate repeat performance the mercury
40 must be broken in such a manner as to leave
a de?nite, uniform and stable retained body at
each operation. For this purpose the conical sur
face It should directly intersect the surface of
the wall l2, which is preferably, but not neces
45 sarily, a plane at right angles to the axis of the
bore III. The angle of the incline formed by
the surface of bore III with the horizontal axis
thereof is low enough to hold the mercury there
upon by the surface tension of the mercury, so
as to give it a de?nite snap action on breaking,
and thereafter a de?nite travel'or run substan
tially as a free body. This angle may be of the
order of between 1 to 12 ‘and 1 to 20.
In Flames 13 and 14 I have illustrated the
manner in which contact is made and broken
when the inclined surface A of the ceramic B
does not intersect the wall C which defines one
side of the mercury pocket but leads to and inter
sects a cylindrical wall D that intersects surface
C. In this construction, tilting of the switch as
indicated by the arrow in Figure 14 causes the
mercury to be attenuated between the mercury
pocket and the inclined wall. The point of great
est attenuation is on the line E, which is the
junction of surfaces A and D. But this point
of maximum attenuation is not so sharp and de
cisive as desired, and breaking of the body of
mercury may occur anywhere along the surface
I)_, with a piece of mercury resting upon the sur
forward slowly, a part J may run over the ridge 15
E and momentarily close the circuit and then
part at the ridge'E and open circuit until the
_main body H closes the gap and again closes the
circuit. Also, if the body retained in the pocket
has a small overhanging portion lying on surface 20
E the angular position at which closure will occur
will vary and sharp, accurate operation of the
switch cannot be assured.
The heating caused by closure and opening of
the circuit by such a switch is excessive because 25
of the unnecessary attenuation and unnecessary
arcing produced by the device.
The switch shown in Figures 3, 4 and 5 is simi
lar to the switch shown in Figure 1, except for
the application of asealing coating indicated at 30
29, formed of a‘ suitable compound, such as
"Bakelite”, cellulose acetate or the like, which
completely encloses the switch envelope and seals
the same.
This provides a more or less resilient
coating capable of absorbing impacts and the 35
like, preventing damage to the interior of the
switch due to dropping of the switch or the like,
and in addition provides an insulating surface
which may be attractively ?nished for advertis
ing purposes or-the like. The characteristics of 40
a relatively stable body of mercury I 8 and a sharp
cutting edge on the insulating surface over which
contact is made and broken is embodied in this
switch, and no further description thereof is be
lie'ved necessary. The construction and mode of .45
operation is essentially the same as that of Fig
ure 1.
With respect to the switch shown diagram
matically in Figures 6 and 7, this switch provides
a drawn steel shell or the like indicated at 30, 50
which at its open end is joined in any desired
manner to a ccaxially extending ceramic insert
or the like indicated at 32, which ceramic is closed
at its open end by a second steel electrode or
other suitable electrode such as ‘a cap or plate 33. 55
The electrodes 30 and 33 are connected to any
suitable source of current supply. It is obvious
- that the electrode 33 need not be of the partic
ular diameter shown, nor be formed as a disc,
‘within the purview of the present invention. It 60
maybe set into the ceramic or it may be in the
form of ,a. cup, as shown in Figs. 10 and 11,
abuttingthe end of the ceramic to de?ne the‘
mercury pocket.
The body of mercury indicated at 34 is trapped 65
between the substantially radially extending wall
35 terminating the tapered spillway surface 36
which extends longitudinally of the ceramic 32,
and the spaced wall or surface of the electrode
70 face D in unstable position and condition. Also, 33. The spacing between the walls 33 and 35 70
depending upon the speed of tilting, the point is of the order of J; of an inch, and insures that
of breaking will vary and no two operations of the body of mercury trapped therebetween in the
breaking are alike. If the break is slow, rupture, annular groove de?ned by these-walls and by the
of the mercury will tend to occur on‘ the ridge extending flange portion 31 of the ceramic will
inherent stability tending to retain "
or line E, leaving a small body of mercury on '
within; the groove throughout the entire operat— .I employ the same in‘ anhydrous £12311 and sub‘
ing angle of the switch. The pocket may be of
stantially chemically pure. ‘I am a vised that di
less length than that?indicated, but ithen the; and mono ethanolamines are included, even
though the material is sold'as chemically pure
trieithanolamine. I intend, therefore, to include
maximum-height of the mercury will not be at
This construction insures that the same quan
' 'tity of mercury will iremain in'the 'groove or
mono- di- and trietlianolamine.
. In a hydrogen ?lled switch, oxides'are reduced
pocket {at all .times, and thus the same angle of
by action of the gas, and the dust-formed thereby
tilting will invariably cause the body of mercury
lies; over the surface of the mercury.
38, whichis in contact with the electrode 30, to
dust is not a conductor, any appreciable amount 10
If thisinto
with the
the length
body ofofmercury
two menis
cus curves, aspreviously pointed out, the body
of mercury will be unstablei and upon switch
15 opening movement, either rapid or slow, more or
less mercury, respectively, may leave the groove
34 and run down the, surface 36.' In such case,
upon reclosing of the switch, a greater or smaller
angle of inclination may be necessary, depending
20 upon the volume of mercury trapped against ihe
electrode 35. Thus the switch will not open and
close the circuit invariably in response to a cere
Asf'this -
of it will prevent good clean mercury 'eontact. By
introducing clean mercury (exide free) treated as
aforesaid into an envelopetj‘rliat has been cleaned
of everything but the atmosphere, then by evacua
tion removing’ mos; of this atmosphere, there is 15
left a slight amount of oxygen. By action of the
triethanolaliniine in the presence of an arc, this
‘oxygen is combined with :triethanol‘amine; and
forms an alcohol, which is in a gaseous form and
the triethanolaminle is changed toward a di 20
ethanolamine'. . This prevents the deposit of any
dust or granular, noncondncting material on the
surface of the mercury, eaving substantially a_
tain inclination, as is desired?for repeat perform
ance, and consequently the switch cannot be used chemically cleansjurface. ,
The liquid which I employ provides arelatively 25
25 for accurate control, purposes. By the provision
of a surface which slopes immediately from the tough ?lngi enclosing the bodies of mercury and
sharp cutting edge de?ned by the junction of the .also lying *over the internal surfaces of the switch,
surfaces 35 and 36, no tendency of the mercury to but is vaporized upon su?icient heating so that
the-vapors thereof are capable of transmitting
break anywhere along this surface will be pro
and dissipating heat generated by arcing between
30 vided,ssinceithe thinnest section of mercury, dur
ing switch opening movement, will always be at the two bodies of *mercury to all portions'of the
this shoulder, and consequently the rnercurywill switch envelope, thereby'iltransmitting the heat
break at this point before any possibility of its away from the point of heat generation and keep
breaking at any otherpoint is presented. ‘Thus I ing the switch of substantially uniform tempera
35 the making and breaking of circuit will always ture andgérelativeiy cool. In addition,'th'e liquid occur over this shoulder, and since the volume of possessesarc extinguishingcharacteristics and in
mercury ,3; remains substantially the, same at all the formr'of a'?lm is electrically puncturable in
times, it will maintain a certain constant surface Eirder that the potential’across the two bddies of
area which can be contacted by the approaching mercury will puncture the ?lm to; allow the-con
tacting of these two bodies of mercury for com
40 edge of the mercury 38, and which will be en
gaged by the approaching‘ edge ofgthe mercury
35 only upon a predetermined inclination of the
switch. For this reason the switch. gives positive
repeat performance, .and thus can be employed
45 under the most sensitive conditions met with in
calibrated’ instruments, and other mechanical
pleting the circuit.
As a result of my ~investigation, I have .found
that triethanolafrnine seijves admirably for this
purpose,;being an anhydrous alkaline liquid which
increases or promotes the surface tension char-"I 45
acteristi'cs of themercury, facilitates movement of
unercury' upon metallic surfaces, and because of
In Figure 8 I have shown diagrammatically the jits absorptive characteristics with respect to
manner in which an .increased surface. cgntact' 'fwater. The combination of hydrogen and oxygen'
‘ and electigeimechanical motions.
Qwithin the switch during arcing ‘may form a cer— 50
50 between the two bodies of mercury may be at
'tain amount of water which would be injurious
tained iniorder to insure a sufilcientcross-sec
tional area of mercury for earring heavy cur--v vto the metallic surfaces within the ‘switch. This
rents required by certain :circuits which may be
controlled by the present Virtype of switch.
I have found ethat cetain insulating liquids
possess characteristics which render them highly
desirable for use in switches of this character.‘
desirable characteristic is that they preserve,
combination of'lthe oxygen with the liquid is es=
pecially advantageous in that vduring ?lling of
the switch there may beoccluded gases contain 55
ing oxygen within the switch envelope which are
not removed by evacuation, and which w'culd have
a deleterious effect upon the interior of the switch
to a large extent, the surface tension of the mer- j if permitted to act upon the ferrous surfaces, or
the mercury.
60 cury in order that it may stand at its full Yrnem's
_ cus height. These liquids are peéuliarly'effective
I‘ have also found‘ that triethanolamine is es
pecially adapted for myf purpose in that it is read
envelope to facilitate meivement of the mercury ily puncturable when placed under pressure be
therealong, and
also cieansing and maintain 'tween:two approaching bodies of mercury, and
upon, the contact between these bodies of mer 65
65 ing clean the internal surfaces of the switch to
' keep them free from scum, foreign particles and g cury, any arcing or sparking therebetween wiil
the like, which are ?oated or absorbed into ‘this _i serve to volatilize the ?lm and dissipatei the heat
in lubricatingthe internal surface of the switch
’ of the arc to all portions of the switchfenvelcpe.
H I have employed ethyl alcohol, castor Tl, glyc
70 :erine, and triethanolamine for' this purpose.
?nd that alcohol, castor oil and glycerine have
cerain characteristics rendering them advanta
geous for use ina mercury switch, but they allow
formation of gi’pbules which are di?icult to re
75 unite. I have found triethanolamine preferable.
In addition, the ?lm prevents; a relatively thin
sliver of ‘mercury running ovef the sharp cutting
edge and producing an arc with the stable body
of mercury, which arcs would tend to break down
and destroy this cutting edge. By the provision
of the ?lm, all arcs are kept away from the ce
ramic‘ edge, and by reason of the relatively large
surface areas which merge upon puncturing of
the stable body of mercury 58. The electrode 55
the ?lm, substantially no arcing takes place, and
has a stem 59 the .outer end of which is threaded
to receive nut 50. A suitable body of mercury
62 is adapted to travel into and out of engage-.
ment with the stationary body 58 to make and
the contact is made over a surface su?iciently
removed from the sharp cutting edge so as not to
damage this edge.
Referring to Figures 8, 10 and 11, the edge of the
advancing body 38 as shown in Figure 8 ap
proaches the adjacent surface of the stable body
- 34. This stable body 34 is but slightly distorted
'10 by gravity and standswell above the breaking
edge 22. Thetough film of triethanolamine 42
or other ‘similar liquid adheres to the surface of
' the mercury and is not easily pushed aside or
squeezed out. If no potential to break the ?lmv
15 is applied the ?lm will continue to hold as the
two edges of the adjacent bodies of mercury ?at
teri each other, as indicated in exaggerated form
in Figure 10, squeezing the ?lm between them as
indicated at 39. The moment the ?lm is broken
20 the two bodies of mercury promptly merge, as in
dicated at 40, and thereupon the two bodies equal
ize and the surface of the mercury then levels
itself as indicated in Figure '7. It is to be ob
served that the electrode 33 shown in Figures 10
25 and 11 is in the form of a cup for de?ning with
the ceramic 32 the retaining pocket or groove for
the body 34. Such an arrangement of electrode
33 provides greater area of contact between the
body of mercury 34 and electrode 33.
Even when normal potential is applied the
tendency is for the ?lm to hold the two mercury
bodies apart, each with ‘a high meniscus, until
the ?lm punctures and allows the two bodies to
merge, with ample conductivity. The tough alka
35 line ?lm provided by the triethanolamine, which,
even in the presence of oxygen and the electric arc
remains alkaline and protects the metal parts, and
saves the sharp edge of the ceramic from injury
by the arc, is an important feature. The heat dis
.40 sipating character and the pressure limiting char
acter of the limited liquid ?ll is of importance.
In Figure 12 I have illustrated, on a slightly en
larged scale, a form of heavy current switch suit
able for heavy duty. This switch is rated at 35
45 amperes and will stand, on a resistance load, more
thanv double the rated amperage inde?nitely
without undue temperature rise. On a lamp load
(tungsten lamps) the initial rush of current is
7' about 100 times running load.
Motor loads draw
about 3 to 5 times normal load. The standard
break circuit as the switch is tilted alternately
one way, then the other. v The-ceramic 49 has an
outer cylindrical portion 53 of substantially less
diameter than the inside diameter of the enlarged
portion 41 of shell 45. The left hand or for 10
ward end of the ceramic has a tapered'shoulder 54
extending to a blunt taper at 63 which is sub
stantially parallel to the conical portion 48 of the
The ceramic 49 and the electrode 55 are en 15
closed in a soft, tough cup or envelope 64 of
rubber or a synthetic rubber substitute, having a
cylindrical portion 65, a ?ange 66, and a bottom or
back 51. This bottom or back 51 is perforated to
pass or receive the stem 59. A plate of insulation, 20
58, preferably formed of “Micarta” or canvas im
with a synthetic resin such as
“Bakelite" overlies the bottom or back 61 of the
rubber cup 64. This washer or plate 68 is rela-.
tively stiff but is also tough and will gradually 25
deform under excessive pressure and heat, but will
not shatter. It fits quite snugly in the bore of the
enlarged portion 41 of the shell. It is backed up
by a steel retaining ring 59 having an internal
diameter less than the diameter of the electrode 30
55, whereby it overhangs the periphery of the
electrode when compressed into position. The
edge of the shell as at 10 is beaded over the ring
to compress "the rubber cup or envelope 64.
pressure of the plate 68 is transmitted directly to 35
the back or bottom of the rubber cup.
This does
two things; ?rst, it forces the electrode 55 against
the ceramic‘ 49, pushing it against the ?ange 66,
which ?ange is compressed between the tapered
shoulder 54 of the ceramic and the tapered wall 40
49 of the housing. Second, the pressure tends to
flow the rubber into ?rm engagement with the
cylindrical surface 53 of the ceramic and the con- ‘
taining wall of enlargement 41. The rubber is
like a viscous liquid, substantially incompressible 45
and tending, under pressure, to flow into any
cavity. As a result the assembly is liquid and gas
tight, even under great internal pressures running
as high as_1000 lbs. per square inch.
The nut 50 and the washer under it are prefer; ' 50
test of a 10 ampere switch made with a glass
ably drawn against the insulating plate 69, fur
envelope and having spaced, solid electrodes, is a
ther holding the parts together in more rigid
load of two 200 watt lamps at 115 volts ?ashed
30 times a minute to destruction. My switch
55 sustains the ?ashing test, 115 volts, 30 ?ashes per
minute, of a lamp load consisting of 5600 watts
fashion, particularly serving, by the stiffness of
the electrode 55, to keep the plate 58 from bulging
(in 200 watt lamps) without failure or undue tem~ 1
perature rise.
The switch is provided with a two-diameter
60 tubular iron shell 45 having the smaller closed
tubular portion 46, theenlarged diameter por
tion 41, and the joining conical portion 48. The
shell and electrode are made preferably of sub
stantially pureiron. The shell may be made by
65 drawing or spinning, or it may be built'up by weld
ing, or in any preferred manner. A ceramic 49
of . generally tubular form-has a conical bore 50
terminating in a sharpannular shoulder 54. A
counterbore of cylindrical form terminating in
70 the radially extending annular shoulder v52 is
‘formed in the right hand end of the ceramic’ as
viewed‘in Figure 12. The iron electrode 55 hasa
short cylindrical extension 55 which extends into
the counterbore to. define the back wall of the
75 mercury retaining groove or pocket 51 containing
out at the center. If desired, the stem 59 may 55
be made hollow so as to permit beading the edges
over the washer to serve as a ?xed assembly before
or after insertion of the assembly into the en
larged-part 41. In that event the hollow bore of
the stem may be threaded for the insertion of a
clamping stud for a terminal or a terminal lug
may be clamped under the beaded edge of the
stem. If desired, an insulating ?anged ring may
underlie the ring 59 to interpose a barrier between
the central terminal and the shell or the ring 59.
. The interior of the shell is provided with a
limited supply of triethanolamine. For a 35
ampere switch having an internal volume of the
order of 21 cc. I provide a'mercury body of the
order of 7 cc. and triethanolamine of the order 70
of 1/2 cc. The mercury that is employed is ?rst
treated as described in copending application,
Serial No. 67,816, aforesaid.
The operation of the switch shown in Figure 12
is substantially as described in connection with
Figures 6 to 11. The throat of the bore 58 is large
because of the offsetting of the ceramic ‘in the,
enlarged portion of the shell. The angle of the
conical bore is made very low because of the
may be as low as 3° to 5°.v The deslderaturn is to
any crack or joint in the ceramic or between the
electrode and the ceramic is completely sealed
determine the point; of break on the edge 5l-so as
to secure accurate repeat performance. This re
' The backing plate 68 of “Micarta”, impregnated
freedom of travel of the mercury.
This angle
against leakage electrically and mechanically.
_ canvas, or the like, bears against the rear or
The surface of bore 50 need not be a true cone, ‘bottom wall 61 of the rubber envelope 65. A
quires an angle under 90°.
the cup may, if desired, be divided but there is a
distinct virtue in having a substantially imper
forate envelope about the ceramic and the elec
trOde-in this and the other modi?cations so that
but should be a surface of revolution so that the
switch may be utilized in any angular position.
A tapered surface at 58 on the spillway is desired
for the accelerating effect on making and break
-15 ing. A substantially true cone is preferable, as
I ?nd that the action of approach and retreat is
thereby made substantially uniform and more ac
curate repeat performance under various speeds of
tilting is secured. The housing provides free
20 runway for the traveling body of mercury 62.
It is therefore believed apparent that I have
provided a switch possessing-the characteristic
steel ring 69 ?ts inside the enlarged shell portion
41 and is in turn engaged-by the spun rim 16. The
ring 69 and plate 68 are solidly pressed against
therubber envelope to put the same under ?rm
pressure and then the rim'is spun over as at 10. 15
The electrode 14 has a sleeve projecting through
the disc portion 61 of the rubber envelope 65 and
the safety disc 68. This disc 68 is tough and will
gradually deform under heat and pressure pro
viding a highly desirable safety feature.
, The elasticity of the rubber envelope is useful
in this connection as it will retaina seal of insu
of repeat performance, provided by'the retention
lation though the safety disc and its electrode be
outwardly displaced. It is to be noted in this con
electrode, and the provision of a sharp‘ cutting‘ nection that the electrode disc 14 is of a diameter 25
edge over which the other body of mercury makes ' not much less than that of the inner diameter of
and breaks contact with the retained body or ring 69.
mercury. In addition, by the provision of the
The stem 59 may be constructed as described in
liquid ?lm, I insure that a sufficiently large‘sure connection with Figure 12. ‘I have shown a nut
'30 face area of contact will be provided to reduce the 68 and washer on stem 59. Thisnut and washer 30
resistance through the mercury for carrying rela
may be employed to draw the electrode 14 and
safety disc 68 toward each other upon opposite
‘tively heavy currents.
In Figures 15 and 16 I have illustrated a modi
sides of rubber disc 61 to' ensure a ?uid-tight
?ed form of my invention. This switch is simi
joint about stem 59. Although it is intended that
35 lar to the switch shown in Figure 12 but has a sufficient pressure be placed upon the rubber en 35
modi?ed form of-ceramic and mounting therefor. ~velope when the ?ange ‘I0 is beaded over to ac
The throat ‘I3 is smaller as is suitable for a switch complish a seal both about stem 59 and also at the
of lower amperage. The length of the enlarged ' joint. between the electrode ‘I4: and ceramic 15.
portion of --the_ shelliis reduced in this form of The electrode 14 may be constructed as shown in
service because the ceramic ‘i5 is extended into Figure 12 if desired.
the bore of the'main‘ shell portion 46. ' The for
The inside of the switch is cleaned, evacuated
ward end-left end in Figure 15-of the ceramic and ?lled as described in connection with Figure
of a stable globule of mercury in contact with one
15 terminates in a square end face 16 of less
radial thickness than the height of the meniscus
45 of mercury 62. Obviously the edgemight be
brought down to a thinner section but I have
found this to be less desirable because of the
resultant weakness and consequent tendency to
fracturehboth in manufacture and in use. The
length of the spillway 58 in my switches is made
great enough to-insure complete disconnection
.i.‘e., an adequate gap for voltage to be impressed.
I prefer to make this distance generous, both for
v the factor of safety in voltage and also to pro
12 with a suitable amount of cleaned and pre
pared mercury and a small amount of ,triethanol
amine or like anhydrous viscous alkaline liquid. 45
Hydrogen gas orcarbon monoxide or even city
gas or any ?xed hydrocarbon gas rich in hydrogen
may be employed to ?ll the envelope.
The operation of‘the switch shown in Figure
15 is substantially the same as that shown in 50
. Figure 12.
It is to be observed however that.the mercury
62 must climb above the shoulder 16 before it
?ows up the spillway 5!! on the ceramic in the
action of closing and on opening the mercury 62
runs off into the shell beyond the shoulder 16.
Obviously the shell might be contracted in di
ameter beyond the shoulder 16 but this would re
vide an adequate runway to accelerate the run,
of the movable body of mercury 62. I also aim
to make the body of mercury v62 ample in length
for two reasons, ?rst to provide a large area of
contact with the shell 46 when the two bodies of ' duce the width of the mercury body 62 and reduce
mercury 62 and 58 are united, and second'tov ‘the area of contact with shell 46.
to avoid the possibility of too ‘greatly reducing the
In Figures 17 and 18 I have shown a modi?ed
contact in the event‘that the switch is ‘thrown form of switch when the ‘two bodies of mercury
further than necessary to close the circuit. , ' V
811V and 82 are separated by a~tubular portion 83
The ceramic 15 has a tapered shoulder‘ 11 be ,of the ceramic 84. The ceramic 84 has an en
tween the front portion of reduced diameter and larged head portion 85 provided with shoulder 86.
‘the rear portion. The electrode 14 is received in
Within the bore of the tubular ceramic is dis
a counterbore in the rear of the‘ceramic and posed the hollow electrode shell 81. which is a
rests against a shoulder ‘I8. The annular recess closed end cylinder ?tting closely in the bore. A
between annular shoulder 52 and the electrode 14 stem 59, which may be of copper or the like. is
welded, brazed or otherwise ?xed to the outside 70
70 retains the stable body of mercury 58 as de
scribed above, particularly in connection with wall of the bottom portion 88. (See Figure 19.)
Figures 8 to 12. The ceramic ‘l5 and electrode 14' A ?ange either in the shape of a separate ring 89
attached by welding, brazing or the like. or in
are held in the soft rubber ‘(natural or arti?cial)
cup 65 which has the cylindrical portion 64, the the shape of a folded ?ange 90 as shown in Figure
75 ?ange 66, and the back or bottom 61, Obviously _ 20‘ is‘received in a counterbore in the rear end of
the ceramic to locate the electrode tube or cup 81 the inner surface of conical wall 48. The tend
in the bore of the ceramic. The ball surface 92 ency of this construction is to cause a relative
of the bore serves as the breaking surface or gap slippage of the porcelain insulator 49 with respect
between the two mercury to mercury contacts. to rubber ?ange 66 when the device is assembled.
The forward end of the tube 83 is preferably and the bead or ?ange ‘i8 is rolled over to com
chamfered off to provide a sharp circular cutting press the parts. This results in a compression
edge 93 for parting the mercury bodies when they stress not only on the tapered surface 54 but also
are merged. The main portion 94 of the envelope ' the cylindrical surface 53, as the rubber is quite
or shell which is preferably made of pure iron soft and is easily distorted or deformed, particu
10 contains a body of mercury 80 which has a menis
cus 95 at the end of the bore 92 rising up to
form a substantially stable, i. e., completely curved
top or meniscus portion so that a substantially
stable form is maintained for all angles required
15 for operation of the switch.
The enlarged portion 85 of the ceramic is en
cased in the soft rubber (natural or arti?cial)
cup or envelope 65 having the cylindrical portion
64, the ?ange 66 and the bottom or disc portion
A “Micarta”—canvas impregnated with a
larly by slight amounts, although it is tough and 10
resilient. The entire external periphery of the
ceramic insert in Figure 12 and likewise the por-'
tions con?ned within the enlarged portion of the
shell in Figure 15 or 17 or any like switch may
e made conical if desired. Likewise the enlarged 15
shell portion need not be cylindrical, but may be
made conical to conform to a similar shape of the
While I have indicated that the free space in .
the envelope may be ?lled with hydrogen or other 20
synthetic condensation product such as “Bake- ' reducing gas, or alternatively with an inert gas
lite”-disc 68 overlies the rubber ‘disc 61 and is
pressed against the same to put the rubber under
compression and is held by the steel retaining
‘ring and ?ange ‘Ill.
The shell has an enlarged portion 96 which has
the forward shoulder 91 formed by beading in the
junction of the main portion 94 and the enlarged
ceramic retaining portion 96. Obviously the main
portion 94 may be of the same diameter as the
portion 96 .but a larger quantity of mercury will
be required unless the ceramic is thickened along
the portion 83.
The preparation for ?lling and the ?lling are as
such as vhelium, argon, etc., I wish to point out
that, ?rst, a gas ?lling of the envelope is not
necessary. I may provide only a ?lling of etha
nolamine vapor at less than atmospheric pres 25
sure, _as disclosed in ‘my copending application,
Serial No. 745,842. Second, the liquid appears to
make the use of hydrogen or the like unnecessary.
The ethanolamine as herein disclosed has many
‘useful properties in this connection. It appears 30
to have the ability to dissolve such slight coatings
of dioxide of iron and of mercury as might result
from any residual oxygen in the parts or in the
vapor space. Thereby it renders hydrogen un
It appears to have valuable sealing 35
described in connection with Figure‘ 12. A limited ‘ necessary.
quantity of triethanolamine or equivalent liquid
is employed.
The operation is as follows: Assume the switch
is substantially level as shown. Sufficient down
40 ward tilt of the left hand end to start the mercury
body 82 moving results in travel into engage
ment with the meniscus 95 which rises slightly
due to the ?ow of some of the body 89 to the left.
The two bodies thus advance to meet each other.
properties in conjunction with the rubber gaskets,
and it appears to seal off any pores or minute
openings in the shell or its cooperating parts.
The use of a stable body of 'mercury is especially
desirable in that a body of this size will retain its 40
form, within limits, regardless of position; that is
to say, a globule of less than twice meniscus curve
size will remain unchanged in form even when
moving down a polished vertical surface. In glass
envelope switches it is impossible to use a stable 45
tains the meniscus of both bodies of mercury -body of mercury of 3%" dimension, since the end
high and is squeezed between them until it is of the glass tube is too close to the point of arc.
either forced out or punctured electrically.- The This proximate arc causes the glass to spall and
two bodies then merge and connect the electrode break. The present metallic envelope can take
50 81 and the shell 94. The cooling of the mercury this arcing and not be damaged or changed.
I am aware that certain modi?cations of the‘
in contact with the shell 94 both by direct con
45 The limited liquid ?ll of ‘triethanola'mine main
tact and by the limited liquid ?ll is highly effec
Upon tilting in the opposite direction a part of
55 the merged body of mercury begins to retreat into
the bore 92 and inside the tubular electrode 81
until a point is reached where the tension of the
invention herein disclosed will at once be ap
parent to those skilled in the art, and'I do not
intend to limit my invention to the specific em
bodiments herein shown and described, nor to the 55
speci?c details shown and described, except as
recited in the appended claims, and I intend to
body of mercury over the sharp annular edge 93
claim the invention as broadly as it is novel over
produces a break. Then the body 82 retreats over
the prior art.
I claim:
1. In. a metallic envelope type of mercury
60 the bare part 92 of the bore thereby breaking the
circuit. The break is sharp and decisive. The re
maining meniscus 95 at the end of the tube 83 is
stable and does not dribble. Excellent repeat
It is to be observed that in the switch of Figure
switch, a pair of electrodes, one of said electrodes
being disc-shaped, a ceramic having a spillway
surface between said electrodes, said ceramic en
tirely supporting and de?ning with said one of 65
said electrodes a retaining groove of a width not
exceeding 315", a body of mercury in said groove
in contact with said-oneelectrode, and an acutely
angled cutting edge between said body of mercury 70
and said spillway surface.
2. A mercury switch comprising a pair of elec
trodes, one of said electrodes comprising a cylin
drical metallic shell, 9. ceramic ?xed in said shell
75 12 the wall 54 has a lower degree of taper than
adj acent the open end of said shell and supporting 75
performance is secured.
The switch operates at a very small angle and
produces a rapid make and a rapid break due to
the movement of both bodies of mercury. Heavy
current can be carried by suitably proportioning
of the parts. The size of the bore 92 with con
sequent control of the cross section of the con
' necting mercury governs the current carrying
ability of the switch.
- 1CE "j
and'spacing said other electrode within said open portion, a ceramic having a conical bore termi
end of said shell, said ceramic de?ning with said . nating in a sharp acute-angle annular shoulder,
other electrode an annular gg'oove of axial extent a disc-like electrede spaced from the shoulder
v such as to retain a body of mercury that will be and closing the. adjacent end of the ceramic and
pocket, said electrode having’ ‘axial
5 . inherently stable-within vthe operating angle of de?ning
said switch, and a sharp cutting edge formed by and radial abutting engagement ‘with said ce
said ceramic and terminating an inclined runway ramic, a retained body of mercury in said pocket,
between said stable body of mercury and a second a rubber-‘cup enclosing said ceramic and the
rear face of said electrode-andjholding them
body ofv mercury carried 'by ‘said shell. _ . I .
3-,. In a metallic envelope typefof mercury within said enlarged portion, and a planar in
switch, a pair of metallic electrodes; one of said sulating closure plate for said enlarged portion
electrodes‘comprising a circular disc, an annular
A mercury
housing. switch of the metal envelope type
spacing insert of ceramic material between said of’7.the
electrodes and having a tapered'spillway surface having refractory therein, and sealing means
15 therebetween, said insert having an acute angle .in said envelope; for axially and radially com
T ,
pressing‘ and ?oatably supporting said frefrac- ‘f
tory therein.
. edge at the smallrend of said spillway surface
and de?ning with said one of said electrodes an
annular radially extending groove, said insert en
tirely supporting. and spacing said. electrode
20 within said other electrode, a body of mercury
8. A_ mercury switchof the metal envelope type ’
having a ‘refractory and an electrode forming ’
with said refractory a iiecess spaced from said 20
envelope, elastic compressible sealing means
stability throughout the operating range of move holding said refrac‘ory and electrode in position
with respect to said envelope, and a» planar rigid"
ment of said switch, and a second body of mer
cury in contact with said other electrode and compression disc engaging the radial face of saidi
in said groove of 'a size such that} it retains its
-25 capable or movement up and down said spillway
surface into and out of contact with said stable
body of mercury, said edge and the stabijdty of
said one body of mercury insuring junction and
9. _ A mercury switch of the metal envelope type
having a ceramic insert provided with‘ an axial
passage theretln‘ough, an electrode closing the
severanceofsaid bodies at thejisame angular -.outer end of said passage; and; resilient sealing
means supporting said5 elecfrode in axial abut
30 inclinations or said switch during: successive op
ting engagement with said insert to position and
erations of said switch.
" ',
4. A mercury switch comprising a cylindrical radially and axially cushion said insert within
the envelope of said switch.
metallic shell having an open end, a ceramic dis
10. in a switch of the class described, a tubu;
posed coaxially a; said shell at said open end and
35 having afradially inwardly inclined spillway sur 1 lar metallic shell closed at one end and having 35
,face leading from the interior of said shell, in ’ an enlarged opening'at the other, and a rigid
electrode supported by and insulated frcm said, . disc of insulation closing the open end, the mar
gin of the open end being ?anged over the edge
shell by the outer end of said ceramic and de
of the disc, an electrode extending through said
?ning with the small endroi said'surface an an
disc, a tubular ceramic supporting the electrode 40
' nular groove having anaxial extent not-substan
in one end thereof, and a body'i'of mercury in the
» tially exceeding the length of two meniscus curves .
of mercury, bodies of mercury in said shell and
11. i’I‘he combination of claim 10 with a rubber
said groove, said body orimercury in said groove seal
between the shell and the ceramic having
being» inherently stable ,and rising radially in-g
radialiy inwardly extending portions at opposite
wardly 5.)! said ceramic above the edge de?ning;
,the inner end orsaid spillway surface, said other: . >
ends of said ceramic. "
12. 'The combination of claim 10 with a rubber
'body of mercury moving on said spillwagisurface - envelope
embracing the outside surface of the '4
into‘ and .out or contact with'said stable bod};v ceramic and the rear face of said electrode for
of mercury, and an acutely angiedcutting edge; sealing the ceramic téj. ihe'electrode.
50' terminating the ‘spillway side lot ‘said groove, ,
whereby said‘other body of'inerclll'y successively end'tubular 's'netallic shell having a main bore 5°
moves into andaiut of contact ‘at said edge.
and having ‘an extension of enlarged diameter
5. A mercuryiswitch comprising two electrodes openiat its end, a closure_of insulation for said
spaced; apart by a ceramic member having an open
end, a ceramic having a- tapered conical
axiallysextending tapered passage theret'hrough, bore disposed
in said extension and having-the
,the larger endggot said- passage terminating in
larger end or its conical boife substantially the
_ 'one of said electrodes, the'other- of said elec-_ same size as the main bore ofithe shell to provide
trodes comprising a disc or a'fdiameter smaller 5 a passageway for mercury} which passageway
than the external diameter‘ or said insert, and provides a maximum width-of mercury at the
the smaller end of said passage terminating in an most constricted party of said bore, a body of to
acute angle ‘de?ned by a radially outwardly ex
~ tending-wall de?ning, with said other‘ electrode,
an annularggoove or an axial length not ex-i
mercury in the shell, a pocket for mercury being
provided‘ beyond the most cons'ricted part of j'the
bore of the ceramic, and an electrode extending
ceeding seven izhirty-seconds of an inch, a body throughsaid closure and projecting
contact 65
of mercury standing meniscus height above said with the mercury in said pocket, said‘ electrode
edge in said groove, and asecond body or mer being of smaller diameter than said extension
cury movable through said passage for contact
and said ceramic having an annular ?ange be
ing said ?rst bodyot merourygthe axial extent of‘ tween said extensi'cn and the peripheryv of said
s'aid‘g'roove; causing the volume of mercury re
tained therein to remain the same after each
opening of the switch.e
14.‘In ccmbination, in a-' mercury switch, a‘.
bushing of refractory insulation having an inter- .
- " ‘6. In combination, a] ferrous .shell having a . nai; annular shoulder de?ning a wall of a mer
tubular contacting portion, a traveling body :of
merciary in ccntact therewith, an enlarged per
76 tion
forming 1a continuation or said Econtacting
cury retaining pocket, a tapered bcre extending
from said shoulderto provide an insulating run
way for mercury, a tubularrlmetal' shell provided/7‘
, 2,132,921
insert surface supported solely by said insert for
closing the outer end of said bore, a cup-shaped
compressible gasket enveloping a‘ portion of the
with an enlarged sealing portion having axially
spaced inwardly extending shoulders for holding
the bushing against endwise displacement rela
1 tive to the shell, an'electrode having a face there
annular surface of said insert and the outer radial '
. shell, the bushing and the electrode, and means
ber compressed axially against the radial face of
said gasket;
of forming a wall of said mercury pocket, a body surface of said electrode to ?ll said gap and en
of rubber forming a three-way seal between the , close said electrode,'and a rigid planar disc mem
for con?ning said body of rubber under" com
15. An insulating body for- use in a mercury
21. A metallic mercury switchv comprising a
metallic cup-shaped shell having an enlarged
switch comprising a generally tubular body of .
open end, a ceramic insert in said end having an
external annular surface of smaller diameter than
said end to provide an annular gap therebetween,
an electrode supported solely by said insert and
pered intermediate portion, and'a sharply ta
having axial and radial seating engagement‘
15 pered end portion, the bore ofsaid body com
prising a conical portion with its largest diameter thereagainst, said insert forming an annular
adjacent said sharply tapered end portion, the ?ange about the periphery of said electrode, and
conical bore having a throat terminating in a ' a resilient cup having a cylindrical ?ange ?lling
said gap and having an integral planar base en
sharp annular shoulder de?ned by a substantial
closing the end face of said ceramic ?ange and 20
the rear face of said electrode.
ing edge for mercury.
22. A metallic mercury switch comprising a I
16. The insulating body of claim 15 character
‘metallic cup-shaped shell having anenlarged
ized further by a substantially cylindrical coun
refractory insulation comprising a substantially
cylindrical peripheral portion, a gradually ta~
terbore extending from said annular surface to v open end, a ceramic insert in said end having an
' external annular surface of smaller diameter than 25
the end of the body.
17. For use in a mercury switch, an insulator said end to provide an annular gap therebetween,
having a conical internal surface extending from
one end and terminating at its most restricted
portion in a sharp shoulder de?ned by a substan
an‘ electrode supported solely by said insert and
having axial and radial seating engagement
therewith, said insert forming an annular ?ange
about the periphery of said electrode, said elec 30
trode terminating within the axial limits of said
tially radially extending surface, an electrode dis
posed endwise in axial alinement with said body
and in engagement therewith, said electrode and
35 said body "de?ning between them, an annular
integral planar base enclosing the end face of said 35
and electrode assembly comprising the combina
tion of a tubular body of refractory insulation
insert and having a stud extending rearwardly
therefrom, and resilient gasket means having a
cylindrical ?ange ?lling said gap and having an
ceramic ?ange and the rear face of said electrode
groove for retaining a body of mercury in'contact
with the electrode,‘ the electrode having a stem
portion, and an envelope of elastic insulation
embracing the external surface of the body and of
40 the electrode to seal the joint between said body
and said electrode.
18. For use in a mercury switch, an insulator
and electrode assembly comprising the combina
tion of a tubular body ‘of refractory insulation
45 having a conical internal surface extending from
one end and terminating at its most restricted
portion in a sharp shoulder de?ned by a substan
and ?tting closely about said stud.
23. A mercury switch comprising a metallic
cup-shaped envelope having an enlarged‘ end, a
ceramic in said end having an axial bore, an elec 40
trode having radial and axial seating engagement
in the outer end of said ceramic and having its
periphery spaced from said envelope by said ce
ramic, resilient sealing means engaging said ce
ramic and electrode, a disc-like rigid insulating 45
gasket for axially compressing said sealing means
and an annular compression ring engaging said
tially radially extending surface, and an electrode ' gasket and having an internal diameter such that
disposed endwise in axial alinement with saidv _ it overhangs the periphery of said electrode.
24. A mercury switch comprising a metallic 50
body and in engagement therewith, said electrode
and said body de?ning between them, an annular cup-shaped envelope having an enlarged open.
groove for retaining a body of mercury in contact end, a ceramic in said end, a disc-shaped elec
with the electrode, said body of insulation having trode having radial and-axial seating engagement
a tubular extension beyond the most restricted in the outer end of said ceramic and having its
periphery spaced from said envelope by said 65
portion, and the electrode comprising a disc ?t
ting within the tubular extension and having a ceramic, resilient insulating compressible gasket
means of high dielectric strength for cushioning
?ange overhanging the end of said extension.
19. In combination, a metallic switch envelope s‘aid ceramic axially in said L envelope, a rigid
having an enlarged open end, a ceramic insert in planar insulating disc for axially compressing
said enlarged end, said insert having an axial. said gasket means, and a. metallic compression
K bore, an electrode carried by and insulated ‘from
said'enlarged end by said insert, a resilient cup
receiving said insert and said electrode and pro_-_
viding an external annular and radial seal there
for, and a rigid insulating disc within the open
end of said envelope for compressing said cup in
sealing engagement between said enlarged end
and said ceramic and, electrode.
20. In .a metallic envelope type of mercury
switch including a cup-shaped metallic shell hav
ing an enlarged open end,ia ceramic insert in said
end having an external annular surface of smaller
diameter than said end to'provide an annular gap
ring engaging the outer face of said disc and hav
ing an internal diameter such that it extends
radially inwardly beyond the periphery of said
25. A mercury switch comprising a cup-shaped
metallic envelope of two diameters joined by a
frusto-conical section, a ceramic insert having an
external frusto-conical surface and an internal
frusto-conical surface, both said surfaces termi
nating at one end of said insert to form a circular 70
edge of substantially the same diameter as the
smallest internal diameter of said envelope and
disposed adjacent thereto, an electrode carried by
therebetweenand having an axial bore, a disc said insert at the smaller end of said internal
75 shaped electrode of smaller diameter than said surface, mercury in said envelope and a
mercury in contact with said electrode during
normal operation of said switch, and resilient
' means sealing the passage between said frusto
conical surface of said envelope and the external
5 surface of said insert.
recess comprising a‘ frusto-conical raceway open
ing into said'envelope and terminating within ,
said bushing in a radial shoulder, an electrode
supported entirely by said bushing and spaced
axially outwardly of said shoulder, an internal 5 _
26'. A mercury switch comprising a metallic
annular'wall in said bushing extending axially
between said shoulder‘an'd-said last-named elec
trode and lying radially outwardly thereof, a body
switch envelope having a cup-shaped body por
tion and?an enlarged cylindrical open end joined
to said body portion by a frusto-conical section, Y of mercury in the groove forward of said internal
10 a ceramic insert in the enlarged end of said en
wall and extending radially inwardly beyond the 10
velope [having opposed external and internal de?ning edge between said raceway and said
frusto-conical surfaces terminating at the small ' shoulder, a second body of mercury in continuous
end of said frusto-conical section'of said envelope, ‘ contact with said envelope and freely movable
awelectrode disc supported entirely by said insert through said raceway and only partially ?lling
15 and vspaced from the small end of the internal the cross section of said raceway and said shoul- 15
frusto-conical surface of said insert, and axially‘
" compressed sealing means radially compressing a
portion of said insert and sealing the passage'be
tween said shell and the external surface of said
20 insert.
27.v For a mercury switch, a ceramic insert and'
terminal structure comprising a cylindrical por
tion and a head portion, a tapered recess extend
der in switch closed position.‘
29. In a mercury switch, a sealed switch en
velop'e comprising, a metallic cup-shaped shell
having a ceramic insert vsecured within the ‘open
end'thereof, an axially extending frusto-conical 20
recess in said insert within said-shell, an elec
trode spacedfrom the smaller end of said recess,
an annular groove formed by a radially extending
ing axially into the insert, an enlargement at they wall at the small end of said recess and an en
larged annular axially extending wall. disposed 25
25 small end of the tapered recess, the vjunction
' forming-a sharp annular shoulder, said insert I radially outwardly about said electrode, said elec
having imperforate side walls, an axially dis
posed electrode extending into the enlargement,‘
‘ and a stable body of mercury adapted‘ to be
30 trapped in the enlargement by said shoulder ‘and
standing above the edge of said “shoulder.”
28. A switch comprising a cup-shaped metallic
envelope having an enlarged openend, a‘ ceramic
bushing resiliently cushioned and sealed in said
35 end and having an‘ axially extending recess, said
trode having a terminal extending axially out
wardly of said insert externally of the open end.
of said shell, a body ‘of mercury retained in a por-_
tion of said groove in contact with said electrode, 30
and a second body of mercury in'said shoulder
movable into and out of engagement with said
?rst body of mercury upon tilting of said en
' velope, ‘
2,132,921.——Paul 8'. Bear, Elkhart, Ind. SWITCH. Patent dated October 11, 1938.
IIDiScIaimer ?led April 2, 1940, by the assignee, Bucklen-Bear Laboratories,
Hereby enters this disclaimer to claims 8 and 9 in said speci?cation.
[Ojicial Gazette April 30, 1940.]
2,132,92L-Paul 8'. Bear, Elkhart, Ind. SWITCH. Patent dated October 11, 1938.
by e assignee, Bucklen-Bear Labora
Inc. ?led November 22, 1940,
Hereby enters this disclaimer to claim 29 in said speci?cation.
[O?icial Gazette January 14, 1.941.]
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