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Патент USA US2127159

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Aug. 16, 1938.
Filed Aug. 27, 19155
- .
Patented Aug. 16, 1938
Edward Collins, 3rd, Philadelphia, Pa.
Application August 4'27 ,
5 Claims.
This invention relates to mercurial thermostats
used in connection with electric circuits.
The control of temperature in the use of many
things and processes is important in many in
the path of the mercury, as it is caused by the
pressure on the bulb to rise Within the stem
while maintained at a given temperature, which
directly iniiuences at’the same time, the mer
dustries, laboratory work and in various kinds of
researches. Such control with precision has
much to do with the kind of results obtained,
particularly where automatic constant control of
temperature is most desirable. To enumerate
cury within the said bulb and stem.
some of the instances where such control of tem
perature is an important factor, mention might
be made of crystal temperature control for radio
transmitters and kindred appliances, the rubber
industry, both natural and artificial, incubation,
15 milk sterilizers, the oil industry, air conditioning,
including heating and Ventilating, and humidity
control, warming cabinets, industrial baths rela
tive to processes of manufacture, baking, heat
treating of cereals for the trade, chemical proc
20 esses, germ culture, certain machinery, bearings,
the manufacture of paints, drugs., etc., automatic
iîre extinguishing apparatus and commercial
temperature control. In fact, a precision instru
ment for the automatic and constant control of
heat, that can be depended upon, becomes an
important factor as an .addition to equipment
used in any of the above instances mentioned and
in many more.
The main object of my invention, therefore, is
30 to provide a mercurial thermostat for electric
circuits, adapted for use as a contact making
thermometer where precision, as well .as constant
temperature control is highly desirable, having
the thermostat of simple construction, and prac
35 tical to manufacture, while at the same time
affording a delicate manual adjustment, within a
fraction of .a degree, to close or open an electric
circuit for regulating heat for whatsoever pur
pose desired.
In connection with this main object, I desire
thc said construction to include a mercury bulb
and stem, preferably similar to a thermometer,
except having the bulb of a spheroid shape,
capable of being slightly flattened in the direc
45 tion of the axis of that part of the tubular stem,
integral with the bulb, which is immediately ad
jacent to bulb, regardless of whether the remain
ing part of the stem continues straight or at an
angle to stem portion, adjacent the bulb.
1935, Serial No. 38,077
(Cl. 20G-141)
In connection with the thermostat, fulfilling
this main object, I desire to have means, manu
A further object is to pro-vide means for man
ually and delicately adjusting the pressure upon
the bulb of the thermostat, either adjacent the
casing of the thermostat, or by remote control,
having additional means to hold the adjustment 10
secure, once it is set.
In connection with the last named object, I
desire to provide a plurality of adjustments in
connection with the .adjusting means for chang
ing to a coarse or ñne adjustment, using the
' same operating means.
Another object of my invention is to provide a
thermostat construction, which, while fulfilling
any or all of the above named objects, will be
practical to manufacture in quantities, and while 20
providing a closely adjustable instrument, will
not be costly to make and will lend itself practi
cally along the lines of thermometer production,
in the making of the mercury ñlled glass stem
and bulb parts of the thermostat.
With these and other objects which will here
inafter appear, my invention resides in certain
construction of mercurial thermostats, two em
bodiments of which ,are illustrated in the draw
ing. The same is described, the functioning of ‘
the parts is explained, and what I claim is set
In the drawing,
Figure 1 is a front elevation of a thermostat
embodying my invention.
Figure 2 is a sectional, side elevation taken on
the line 2_2 of Figure 1.
Figure 3 is a rear perspective view of the upper
part of the thermostat shown in Figures 1 .and 2.
Figure 4 is a perspective View of the upper 40
part of the compressing lever, shown also in Fig
ures 1 and 2.
Figure 5 is a front elevation of another fo-rm
of thermostat, embodying my invention.
Figure 6 is a sectional side elevation, taken on
the line 6_6, of Figure 5, and here shown at
tached to a wall.
Figure ’l is an elevation showing the front flat
side of the compressing lever with attachments,
which are shown also in Figures 5 and 6.
In the figures, considering Figures 1, 2, 3 and
ally adjusted to eXert a pressure upon the bulb,
4, the casing l0 is shown to have an open back
to sufficiently distort the same to cause the mer
cury to rise in the stem, to close a circuit be
and bottom portion l5.
tween two terminal wire ends, positioned Within
rod I6, near the top portion I4, is an L-lever I'l,
Il, integral with sides l2 and I3, top portion I4
Hinged upon the cross
having an upper portion I8, with ears I9, jour
naled upon the cross-rod I6, ñxed in the sides
I2 and I3. A stem seat 20, depends from the
upper portion I8, of the L-lever I1. Integral with
the portion I8, is the long arm 2l, which is posi
tioned adjacent to the back II. Fixed in the
bottom portion I5 is a bushing 22, in threaded
engagement with the screw 23, which has a cup
portion 24, and a knurled finger end 25. Be
tween the stem seat 28 and the cup portion 24,
of the screw 23, is the glass thermostatic element
26, having a bulb 21, flattened in the direction
of the axis of the element, and having a tubular
stem 28, between the bulb 21 and the stem seat
20. The bulb 21 and the tubular stem 28, are
in open communication, having mercury 29 nll
ing the bulb 21, and extending partly up the
channel 3D, of the stem 28. Considering partic
ularly the structure of the bulb end of the glass
thermostatic element 26, as shown in section, in
Figure 2, the central part of the upper cross wall
portion of the bulb 21, is also the lower solid glass
end of the channeled stem 28, and is therefore
inflexible within the Zone 39. Directly opposite
this upper cross wall portion, of the bulb, is the
lower cross wall portion, having its central part
inflexible, inasmuch as it is part of the lug 38,
thus leaving any flexible action of the bulb to be
had only from the thin, curved wall portions of
30 the bulb, outside of the upper and lower, central,
and inflexible wall portions of the bulb, which
are concentric with the axis of the stern 25.
Penetrating the wall of the stem 28 and enter
ing the channel 30, are the metal wires 3I and
35 32, connected respectively to the metal rings 33
and 34, bound on the outside of the stem 28.
Connected with the `rings 33 and 34 are the re
spective terminal pieces 35 and 36, with eyelet
ends 31. Where the thermostatic element 26
rests in the cup portion 24, of the screw 23, there
is a solid glass lug 38, integral with the bulb 21.
Considering this bulb 21, the Walls thereof, the
upper flattened portion has a zone 39, surround
ing the end of the stem 28, so that any end pres
45 sure coming from the stem 28 will tend to de
press the zone portion 39, of the bulb 21, and re
duce the size of the cavity of the bulb 21, hold
ing the mercury 29, causing the latter to rise in
the channel 30, of the stem 28.
Returning to the L-lever I1 and its long arm
2|, there is shown a screw 48, in threaded en
gagement with the upper bushing 4I, fixed in the
back II, of the casing I0. Midway of the height
of the casing IU, I have provided another bush
ing 42, threaded for engagement with the screw
40, when it is desired to change the screw 39,
from engagement with the bushing 4l, to engage
ment with the bushing 42, so that the .screw 48
can bear against a portion of the arm 2|, further
60 away from the journaled connection of the L-le
ver I1, with the rod I6, when one turn of the
screw 48 will cause considerably less angular
movement of the L-lever I1 than one turn of the
screw will cause, in conjunction with the upper
f- bushing 4I, with which the screw 4D is shown
engaged in Figure 2.
The permissible lower position of the screw 4i),
is shown in broken lines, at 48a. The screw 45
may have its outer end provided with the usual
finger piece, near the housing, or it may be pro
vided with a remote control device, as shown in
the upper parts of Figures 1 and 2, including a
fluted head 43, engaged by a pawl piece 44, hav
ing an elastic arm 45, fixed in a post 48, which
75 itself is fixed in the housing ID, so that we have
a pawl and ratchet connected with the screw 40,
for retaining the same in any angular position
it is put by adjustment.
Fixe-d to the screw head ¿I3 is a flexible shalt
ll'I, terminating in a finger piece 48.
This shaft
¿l? may be any length desired and
as a
flexible shaft to turn the screw ¿lll from a dis
tance. For a safety stop, I provide a pin 5.9, fixed
in the head 43, positioned, and long enough, to
come against the post 45, to prevent any excessive ,
turning of the screw M3, which would tend to
evert too much pressure upon the bulb 21.
Considering now the modiiìed form of my in
vention, shown in Figures 5, 6 and 7, there is a
casing 50, having an open back 5I, sides
top portion 53. Fixed to the casing 58, by spot
welding or otherwise, is a bracket 55., having legs
55 and 55 with out-turned portions 51, through
which pass screws 58, into a wall 59.
Fixed to
the inside of the back 5I, are collars 88 and 6I,
which support the hollow stem 82, of ‘the glass
tl'iermostatic element 53. This stem 82 is shown
to be bent at 54, where the vertical portion 55,
and the horizontal portion. 88, merge. The por
tion 58 passes through a large hole 61, in the
back 5I, oi” the casing 58, and through a smaller
in the plate 58, attached within the
bracket 54.
Seated against the lips of the hole 58, in the
plate 59, is the flattened bulb 1li, integral with ‘
the stem 82. The bulb 1€) has within it mercury
1|, which passes part way into and up the chan
nel 12, of the stem 82. The bulb
and stein E2
are preferably made of suitable glass. Extend
ing from the bulb 18, centrally, to the rear, is
the solid glass lug 13, which is seated in the pock
et 14, of the fiat lever 15. This lever 15 is hinged
with the eye 16, of the bolt 11, which passes
through a slot 18, in the leg 55, of the bracket 54.
The slot 18 extends lengthwise of the leg 55 for 40
adjusting the position of the bolt 11, with respect
to positioning the lever 15, relative to the lug 13.
The bolt 'I1 is secured to the leg 55 by nuts 19.
Journaled in the lower end 89, of the lever 15,
is the screw 8l, having a washer 82a, fixed there 45
to. The screw 8l is threaded with the plate 59,
the bracket 54, and thel casing 58. rI‘he outer
end of the screw 8l has a head 82, with longi
tudinal teeth 83, forming a ratchet with the
spring pawl piece 84, fixed in the post 85, which 50
is fixed in the bracket 54 and the casing 50.
Part of a flexible shaft 36, similar' to that illus
trated in Figures l, 2 and 3, is shown fixed to the
head 82.
Considering the electric terminals of the in 55
strument shown in Figures 5 and 6, the wire ends
81 and 88 positioned within the channel 12, are
connected through the wall of the stem 82 with
the metal rings 89 and 96) respectively. which
are bound around the stem 62. Connected with
the rings 89 and 9U are the respectiveA terminal
pieces 9! and 92 having eyelets 93.
In operation, assume that the bulb 21, of the
thermostat shown in Figures l and 2, is either
immersed in a liquid or surrounded by a gas or
air, as the case may be, and that the tempera
ture of the medium thus surrounding the bulb
21 is the same as that at which it is desired to
check and hold the heat, elfectîng the object or
process to be governed, assuming there to be 70
present, at such object or along with the appli
ances for carrying out a pro-cess, an electrical
controlling device, in circuit with the terminals
at 3l and 32, which will operate, as desired, to
effect a temperature control, upon the closing of
a circuit. Then, while at this given tempera
ture, the screw 40 is turned to bear against the
arm 2|, of the L-lever I1, causing it to turn
about the cross-pin IB and bear down at the
stem seat 2B, so that the tubular stem 28 is
caused to move slightly downward, in the direc
tion of its axis, and depress the zone portion 39,
of the upper wall of the glass bulb 21, and cause
the mercury 29 to rise in the stem channel 30,
passing the wire end 32 and contacting the wire
end 3i, closing the circuit.
The operator carefully observes the instant at
which the circuit is thus closed, and he stops
turning the screw 4Q, at that instant.
The screw
4t may be turned either by directly turning the
head 43, or by using the flexible shaft 41, by
turning it at the finger piece 48, as at a point of
remote control.
In order to hold the screw 4U
at the point where the operator stops turning
the same, the pawl member 44 will engage the
teeth of the head
yet permit the turning of
the screw 4l), manually either way. Unscrewing
the screw 4@ causes the mercury in the stem 28
to recede downward, breaking the circuit.
In the event that it is desired to effect a more
delicate adjustment, by means of the same screw
the screw 49, with its connections, is changed
from engagement with the bushing 4I, to engage
ment with the bushing 42, to occupy the position
so as to bear against the arm 2|, at a point
further away from the pin I5, upon which the
L-lever l1, swings. In this latter case, one turn
part of the stem immediately adjacent the bulb.
Where pressure upon the bulb 21 is brought from
the remote upper end of the stem 28, and is
brought upon the bulb 21 by the stem itself,
pressure upon the bulb 10 is exerted directly
upon the bulb between the plate 69, directly in
contact with the bulb 10, and the lever 15 in
pressing contact with the lug 13, integral with the
bulb 10. This pressure is produced by means of
the drawing eiTect exerted by unscrewing the 10
screw 8i upon the lever 15, the screw being turned
manually by a flexible shaft 86, connected with
tho head 83, and held where adjusted by the
ratchet means including the pawl member 84. As
a matter of precaution against excessive turning 15
of either the head 83, or the head 43 of the
form shown in Figures 1 and 2, I provide the
respective projecting pins 81 and 49, which are
adapted to stop against the respective posts 85
and 4l.
In this application we are primarily concerned
with the thermostatic construction herein illus
trated and described as embodying my invention
and while no specific electrical governing device
for immediate connection with the thing or proc 25
ess requiring heat control, is shown, it will be
readily understood by those skilled in the art of
thermostats, how to make any specific applica
tions of my invention for precision temperature
control, particularly where such precise control
of temperature is to be constant in connection
With the electrical governing device used in the
several instances mentioned above and many
of the screw llt, will cause much less downward
movement of the stem 28, and therefore a less or
slower rise of the mercury within the channel 30.
If desired, ratchet means, having parts similar
use of said thermostat embodying my invention,
to 44, ¿i5 and 46, can be provided also about the>
bushing ¿2, to function with the head 43, when
the screw 4@ engages the bushing 42. Once the
thermostat has been set to close a circuit at the
temperature desired, then as soon as this tem
perature falls, the mercury column will auto
matically fall, opening the circuit which will stay
open, until the temperature is caused to rise
45 again and send the mercury back up the channel
Si), to again close the circuit at the temperature,
While I have above referred to an individual 35
it is possible to use a plurality of such instru
ments for temperature control, by having the
instruments, each set for closing a circuit at
a different temperature, in connection with proc 40
esses or objects, where a succession of various
temperatures is desired to be had, each for a
given period of time, using a timing device to
deñnitely measure the time of duration of the
control of each thermostat, or for this same 45
purpose, instead of using a plurality of such mer
at which it had been set.
curial thermometers, we can have more than
Next, having the thermostat positioned Where
it will be eiîected, simultaneously, by the same
two spaced terminals along the line of the mer
cury channel, in which case the bulb adjustment
would only be possible as eiîecting the lower two 50
of said terminals, as the spacing of the remain
ing termials within the said channel would be
Inasmuch as other modifications than` those
shown and described can be made, without de 55
parting from the spirit and scope of my inven
tion, I wish to include all forms of structure,
which come within the purview of the following
degree of heat, which eiîects the object or process
under consideration, the functioning of the ther
mostat will automatically close the circuit, at the
desired temperature, or open the circuit below
said temperature for which it has been set, to
govern the operation of the electrical device with
which it is> in circuit, and which directly causes
a rise or fall in temperature at the said object,
whose temperature it is desired to govern, or in
connection with the process being carried out
chemically or otherwise.
Referring now to the operation of the modiiied
form oi mercurial thermostat shown in Figures
5 and 6, a pressure upon the bulb 10, in the
direction of the axis of that part 66 of the bulb
stem 62, will cause the mercury to rise in the
channel 12, to close a circuit between the terminal
wire ends 81 and 8S, in a similar way to that de
scribed above in connection with the terminal
wire ends Si and 32, of the thermostat, shown
in Figures 1 and 2 and for similar purposes.
While a rise of mercury in either channel 30 or
12 can be caused by pressure upon the respective
bulbs 21 and 10, there is a difference in which
these bulbs are compressed, although each is
compressed in the direction of the axis of that
I claim:
l. A mercurial thermostat for use in closing an
electric circuit, said thermostat including a cas
ing, a mercury thermometer, a bent stem' to said
thermometer, a channel running longitudinally
within said bent stem, mercury within said bulb 65
and said channel, terminal means in said circuit
entering said channel in spaced relation from the
outside, holding means for securing said ther
mometer to said casing, said bulb being flattened
in the direction of the axis of that part of said 70
stem immediately adjacent said stem, a lug ex
tension on said bulb opposite to and in line with
the last mentioned part of said stem, a bracket
attached to said casing positioned near said bulb,
a leg to said bracket extending at an angle to
said casing, a slot in said leg, extending longi
tudinally of the same, a bolt through said slot
secured adjustably by nuts to said leg, a lever
pivoted to said bolt and positioned to be across
said lug and in contact therewith, a seat for said
bulb having a hole therein through which said
stem part next to said bulb passes said seat being
connected with said casing, and means for ad
justab-ly forcing said lever against said lug, to
10 compress said bulb against said seat, to force said
mercury up said channel to close the circuit be~
tween said spaced terminal means.
2. A niercurial thermostat made in accordance
with claim 1, having in addition retaining means
15 for retaining the adjusted compression of said
3. In a mercury thermostat including a cas
ing, a thermometer having a stem, a bend in said
stem, with a longitudinal mercury channel to
20 said stem, and a mercury bulb, electric terminals
ending in spaced relation in said stem channel, a
seat for said bulb on said casing, positioned oppo~
site the termination of said stein at said bulb, and
means for adjustably forcing said stem, in the
25 direction of its length to compress said bulb be
tween said stem and said seat to cause said rise
in said channel to close a circuit between said
4. In a thermostat having a housing, a ther
mostatic mercurial element of glass including a
mercury bulb, with an integral lug on one side,
and a tubular stem on the opposite side, of said
bulb, terminal wire ends within the mercury chan
nel of said stem, with electrical terminal means
connected with said wire ends, and having said
stem bent, a bulb compressing means, comprising,
a IiXed seat for said bulb, said stern passing
through said seat, a pivcîing element on said
housing, a lever pivoted upon said element and
bearing midway or its length, against said lug,
and means for adjustably forcing said lever to
bear against said lug to compress said bulb to
cause said mercury to rise in said channel to close
a circuit between said Wire ends.
5. A mercurial thermostat for use in closing an
electric circuit, said thermostat including a cas
ing, a mercury thermometer mounted on said
casing, a stem to said thermometer, a hollow bulb
at one end of said stem, a channel ruiming longi
tudinally Within said stem, communicating with
the interior of said bulb, mercury within said
channel and said bulb, terminal means in said
circuit, entering said channel :in spaced relation,
through said stern from the outside, a globular 20
wall forming said bulb, a solid portion to said
globular wall formed by the merging of said stem
with said bulb, a pressure receiving portion to
said globular wall, positioned opposite to said
solid portion, a iiexible portion to said globular
wall comprising the remaining part of globular
Wall between said solid. portion and said pres
sure receiving portion or said wall, and adjust
able means for pressing against said pressure
receiving portion, in the direction oi said solid 30
portion to cause said mercury to rise mechanically
in said stem,
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