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Патент USA US2109169

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Feb. 22, 1938.
2,109,169
0. S._FIELD
THERMAL OPERATED CIRCUIT CONTROLLING DEVICE
Filed Aug. 15, 1934
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INVENTOR _
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ATTORNEY
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2,109,169
Patented Feb. 22‘, 1938 -
UNITED STATES PATENT‘ OFFICE"
2,109,189
THERMAL OPERATED CIRCUIT CONTROL
‘
~
LING
DEVICE
'
Oscar S. Field, Rochester, N. Y., assignor to
General Railway Signal Company, Rochester,
N. Y.
Application August 15, 1934, Serial No. 739,981
1 Claims.
(Cl. 200-122)
'
This invention relates to circuit controlling
devices of the thermal element type.
resistance wire in the ‘usual way, one end of this
heating coil being soldered or welded to an an
' The heating and cooling of bi-metallic thermal
chor member 4 in the stem of the bulb B.
I
In the arrangement shown, two resilient con
tact members 5 and 6 are anchored at their lower
ployed to open or close contacts on a time inter-» ends in the stem of the bulb B, and are connected
together at the upper ends and to the bi-metallic
val basis. In the interests of economy and ef
?ciency, such thermal elements may be enclosed ~ strip 2 by a tie-piece or driver member‘ 1 of suit
in an evacuated or gas ?lled bulb, as disclosed able insulating material, such as mica. Station
ary contact members 8, 8', and ill of similar con 10
10 for example, in my Patent 2,035,426, granted
elements in response to the flow and interruption
of electric current may be advantageously em
March 24, 1936, on application, Ser. No. 634,019,
?led September 20, 1932.
In accordance with this invention, generally
speaking, it is proposed to provide for the ready
adjustment of the time 01' operation of such en
closed thermal elements by varying the rate at
which heat may be conducted or radiated from
the heating element, either by changing the
pressure of the gas in the enclosing bulb, or by
20 ' changing the area exposed to the external air of’
a heat conducting member extending into the
struction are anchored at their lower ends to en
gage the contact members 5 and 6.
These con- -
tact members may be made as a whole of suitable
contact material, such as a nickel alloy; or con
tact pieces may be attached to these members at 16
the points of contact. One end of the heating
coil 3 is connected to the contact member 5.
The arrangement .of ‘contacts illustrated is
merely typical; and‘the contact members may.
part apparent, and in part pointed out as the
be arranged to open or close contacts in the 20
heated or cooled condition of the thermal strip i.
The contact members and the anchor} member
4 for the heating coil are connected by wires to;
pins ii in an insulating base C, attached to the
glass bulb or container B in accordance with reg 25
description progresses.
ular practice.
' bulb into contact with the thermal element.
The various characteristic features, advan
tages, and attributes of the invention will be in
’
The accompanying drawing illustrates in. a
simplified and diagrammatic manner certain spe
clflc embodiments of the invention. Fig. 1 shows
30 the structureof an enclosed thermal element
having provision for adjusting the time of its
operation by varying the pressure of the gas iri
the enclosed bulb. Fig. 2 is a fragmentary view
illustrating the application of a heat conducting
part to an enclosed thermal element device for
varying its time of operation; and Fig. 3 is an
other fragmentary view illustrating a modi?ca
tion of the heat conducting part.
Referring to Fig. 1, the thermal device com
40 prises a bimetallic strip. lot the usual type and
construction, ‘such as brass and- “Invar" strips
fastened together. This member i is anchored at
its lower end in the stem oi a glass tube or bulb
B,'in the usual'way and in accordance with well-=
known practice. A similar bi-metallic strip 2 is
welded or otherwise rigidly fastened to the up
per end of strip I; and the two strips i and 2
are disposed in an opposing relation, so that they
will be deformed in opposite .directlons by a
change in the temperature of both, thereby main
.
r
In the embodiment of the invention illustrated
in Fig. 1, ‘a ?exible metallic diaphragm l2 of
bronze or other suitable material, preferably cor
rugated, is attached to the upper end of the glass 30
bulb B, the edgeof this diaphragm forming a
gas-tight seal with the glass. An adjusting nut
it in a bracket or stirrup i4 suitably secured to
the base C, is arranged to deform the diaphragm
l2. After the parts have been assembled in the
glass tube B and the tube is evacuated in ac
cordance with the usual practice, it is preferably
?lled with inert gas such as argon or nitrogen, to
a pressure conforming with the time character
istics desired.
'
strip 2. Consequently, the upper end of the two
strips is moved or displaced. This movement is 45
assumed to be to the left to open contacts 8-!
and 5-H, and to close contacts 5-8. The time
taken to raise the temperature of the strip l suf
?ciently to cause the necessary displacement to
operate these contacts seems to depend on the 50
taining the upper end of the two strips in sub- ‘ rate at which heat may be conducted or dissi
stantially the same position witli relation to the. pated, as well as the rate at which the heat is
lower end, so as to compensate for gradual supplied. Experiments indicate that the rate at
changes in ambient’ temperature.
The lower
55 strip i is heated by a coil or ?lament I of suitable
40
When electric current is supplied to the heat
ing coil 3, the temperature of the lower bi-metal
lic strip i is raised relative to that of the upper
which the heat is dissipated ‘from the thermal
strip l is due to a large extent to conduction 55
2
2,109,169
through ‘the gas in the tum; and it has been
found, that by varying the pressure of this gas,
the rate of dissipation of the heat may be ma
terially changed so as to increase or decrease
within certain limits the time required to operate
the contacts for the same heating current. Ac~
cordingly, this invention contemplates the prom
vision of the diaphragm i2, or equivalent means,
by which the pressure of gas within the tube can
W be readily varied after the device has been as
sembled, for the purpose of adjusting the oper
ating time of thermal operated circuit controllers,
either to give the same time for a group of like
'15
devices in spite of manufacturing variations, or
to adjust the same device for different operating
times for different applications.
Fig. 2 illustrates another construction in which
a heat conducting member i5 is welded or other
wise suitably iastenedto the lower iii-metallic
strip i, anciis sealed in the glass bulb B with
its outer end exposed to the atmosphere. It is
contemplated that after assembly and test or the
device, the area of the member to exposed to the
external air may be changed by cutting it ed to
v25 diilerent lengths; and in this way'the rate of
disnpation 01' heat irom the strip i may be var»
led to obtain the desired adjustment in operat
ing time. This construction may be used with
evacuated bulbs, as well as gas ?lled bulbs.
Fig. 3 illustrates a. modi?cation in the struc
ture of the heat dissipating member 951, whichis
bent or shaped at its outer end tor the attach»
ment by a screw or the like of radiating disc or
piece M2, the size and area of which can be se
lected to give the desired exposure and radia
tion to the atmosphere.
The speci?c embodiments of the invention
shown are merely illustrative; and various adap
3. A thermally operated circuit controller com
prising a bi-metallic strip within an enclosing
bulb, means for supplyingheat to said strip, heat
conducting means connected to said strip and
extending outside oi’ said bulb, said heat con
ducting means being adapted to have its exposed
area changed to vary the rate oi‘ dissipation of
heat from said strip.
‘
4. A thermally operated circuit controller com
prising two bhmetallic strips mechanically con 10
nected and disposed to be deformed in opposite
directions by a change in'the temperature of
looth, means for heating one of said strips in
dependently oi the other, contacts operated by
the deformation 0! said heated strip, a gas-tight 15
bulb enclosing said strips and said contacts, and
means changeable after assembly of the device,
for varying the rate of dissipation oi" heat from
the heated strip, said means for heating said
strips being electrical heating means having con 20
nections extending outside of said bulb, whereby
the time required to operate said contacts after
application of current to said heating means can
lie-regulated and be substantially constant irre
spective of ambient temperatures.
5. A thermal circuit controlling devicecom
prising, a bi-metallic strip, means for heating
the strip, a closed ?exible gas ?lled chamber en
closing the strip, and meansaccessible from the
outside oi’ the chamber for varying the size of 30
the chamber and thus veil '13 the pressure of
the gas therein, whereby to change the rate of
dissipation 01' heat Irons the bi~metallic strip.
6. A thermal circuit controlling device com
prising, a lei-metallic strip, means for heating
the strip, a closed ?exible gas ?lled chamber en
closing the strip, a closed rigid casing enclosing
the chamber, and means accessible from the
tstions, modi?cations, and additions may be made ' outside oi the casingj for varying the size of the
to the speci?c constructions shown and de
chamber and thus varying the pressure of the
scribed, without departing vfrom the invention. has therein, whereby v"to change the rate of dis 40
‘What I claim is:—
'
slpation 0! heat from the bl-nietallic strip.
l. A thermally operated circuit controlling de»
‘l’. A thermally operated circuit controller com
vice comprising a lei-metallic thermal element prising a iii-metallic strip within an enclosing
in an enclosing bulb, means for heating said ele
hulls, means for supplying heat to said strip, heat
ment, contacts operated ‘by deformation of said conducting means connected to said strip and
element, and means for varying the rate oi’ dis~ extending outside of said bulb, said heat con
sipation of heat from said element.
.
ducting means having receiving and fastening
2. A thermally operated circuit controliins ole
means thereon for holding heat radiating mem
vice of the character described, comprising it lol
hers oi various radiating capacities, whereby to'
metallic strip enclosed in E?hw?il‘id tube, and vary the rate of dissipation oi’ heat by said strip. 50
means adapted to be adjusted after assembly oi’
the device for varying the pressure of the has
i'J?CAR S. FIELD.
in said- tube, and thereby change the rate of iii-i
slpation oi’ heat irom said bi=metallic strip.
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