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Патент USA US2411093

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Nov. 12, 1946.
-
R.‘ P. JAMESON
FIRE DETECTING THERMOSTAT
Filed Sept’. 13, 1944
2,411,093
Patented Nov. 12, 1946
2,411,093
UNITED STATES PTET OFFIQE
2,411,093
FIRE DETECTING THERMQSTAT
Ronald I’urvis Jameson, Christchurch,
New Zealand
Application September 13, 1944, Serial No. 553,932
In New Zealand September 16, 1943
10 Claims.
(Cl. 200—139)
1
This invention relates to improvements in ?re
detecting thermostats.
The object of the invention is to provide a
device that will be sensitive in detecting incipient
outbreaks of ?re under varying atmospheric con
ditions and that can be adjusted by means of a
calibrated device to function with any desired
at either end but so arranged as to- be insulated
from the regulator wheel or its spindle. The in
sulation of this actuating rod from the regulator
wheel or its spindle is to provide that the electric
current must pass through the bi-metallic coils
and thus determine that they are in electrical
continuity and form part of a circuit. ' Attached
minimum rapid rise of temperature.
According hereto, the heat detector is a bi-v
to another portion of the actuating rod is another
hi-metallic coil which is shielded from exposure
metallic strip coiled in a helix in such a manner 10 to the atmosphere by the casing of the device;
that it will rotate in one direction (for example,
the free end of such second coil forms an electric
clockwise) upon being heated, and so arranged as
contact. These coils, when subjected to heat,
to leave it open to the temperature of the atmos
rotate in opposite directions. The contact being
phere of the place where it is mounted. This
the free end of the shielded coil is normally set
coil is connected at one end to a rod which is
in engagement with a ?xed contact, thereby ion-free to rotate with the rotation of the coil as the
ing part of a normally closed circuit. The ten
temperature changes. Attached to this rod is
sion of the contact engagement is variable by
another bi-metallic coil wound in such a manner
adjustment made at the regulating wheel at
that it rotates in the opposite direction with its
tached to the exposed coil. In addition to the
free end acting as a movable electric contact, and 20 ?xed contact above referred to, another ?xed
so arranged that it is shielded from direct ex
contact on the opposite side of the movable con
posure to the atmosphere in order to prevent it
tact is provided to act as a normal open circuit.
from being immediately affected by any rapid
When subjected to slow heating, such as normal
rise in temperature, such as would be occasioned
increases in atmospheric temperature, the ex
by an outbreak of ?re.
posed coil rotates in an anti-clockwise direction
The free end of the second coil which is capable
and in doing so rotates the actuating rod and the
of acting as a contact is set between two ?xed
shielded coil which is attached to it, but as the
immovable contacts and so that it will make con
shielded coil is so arranged as to itself rotate in
tact with one or the other of these ?xed contacts
a clockwise direction, it neutralises the movement
in accordance with certain conditions of tem 30 of the exposed coil at the free end of the shielded
perature, as will be mentioned later. In its nor
coil and no movement of the movable contact
mal position, corresponding with the ordinary
takes place. The purpose of this arrangement
temperature of the room, it will be in engagement
is that the thermostat will adjust itself or com
with one of these contacts, but the arrangement
pensate during normal slow changes of atmos
is such that upon a rapid rise in temperature it
pheric temperature. When subjected to a rapid
will move from the contact and engage with the
rise of temperature, such as ?re, the exposed bi
other contact and so break and make two electric
metallic coil rotates in its anti-clockwise direction
circuits. When the heat of both bi-metallic coils
without a corresponding opposite rotation of the
again stabilizes, the coil-contact moves back to
shielded coil and thus the movable contact of the
its normal position.
In order that the device may be properly set,
shielded coil is caused to break away from en
gagement with its ?xed contact and breaks the
a regulator is provided by which the coils are
normally closed circuit. Further heating causes
rotated to such a position that the movable con
the movable contact to engage with the other
tact is brought under tension engagement with
?xed contact and so to close the normally open
its ?xed contact and the regulator is then secured 45 circuit. The regulator wheel is provided with
in position with ?xing screws. Such tension will
calibrated divisions by means of which the ten
‘be released from such contact only upon a prede
sion of the movable contact against the ?xed
termined minimum rapid rise of temperature, and
contac is adjustable for the purpose of deter
such rise of temperature continuing, the movable
mining or ?xing the minimum rise of temperature
contact will pass to the other ?xed contact.
50 which will free the movable contact from engage
In one form of the invention, the exposed bi
ment with its ?xed contact. Such divisions are
metallic coil is secured. by a screw or the like to
calibrated to provide easy means of visible ad
the spindle of the regulating wheel; the other
justment. of the thermostat and these calibrations
end of the exposed coil is secured by a screw to
also provide a ready means of checking adjust
an actuating rod free to rotate within bearings 55 merits.
2,411,093
4
3
A fusible link forming part of the normal closed
circuit is inserted to limit the compensation to
a predetermined temperature and to provide in
increase of temperature such as would be occa
sioned by ?re regardless of atmospheric tempera
ture at the time of such ?re.
'
When the thermostat is subjected to a rapid
temperature rise, such as ?re, the exposed bi
metallic coil ! alone is immediately affected and
aid of the accompanying drawing, wherein
rotates in its anti-clockwise direction, without a
Figure 1 is a plan view with the end covers 8
corresponding opposite rotation of the shielded
and i9 removed.
coil 4, and thus the movable contact 5 is caused
Figure 2 is a section on the line A—-A in Fig
10 to break away from engagement with the contact
ure 1.
Figure 3 is a sectional elevation of the ap
9 and to engage with the contact it.
>
paratus.
With all changes of temperature, whether nor
Figure 4 is an end View from line 3-13 on Fig
mal or abnormal, the rod 2 is caused to rotate
Within its bearings, thus keeping them free from
ure 3, with the end cover l9 removed.
Figure 5 is an inverted plan of Figure l, and
15 sluggish action at all times, which might be the
tendency were they constantly at rest as a result
Figure 6 is a section on the line C‘—C in Fig
ure 5.
of accumulated dust or the eifects of corrosive
Referring now to the drawing, the thermostat
fumes or the like.
.
comprises a bi-metallic strip I coiled in a helix
The screw 1 provides a means of adjusting the
in such a manner that it will rotate in an anti~ 20 bearing so that there is “float” or side play for
clockwise direction upon being heated and so
the rod 2 and the pointed ends of the same are
mounted as to leave it exposed to the tempera
“resting” on the slopes of their respective bear
dependent means of giving an alarm.
The invention will now ‘be described with the
ture of the atmosphere where the thermostat is
mounted. This coil is connected at one end by
ings, thus providing the minimum of frictional
resistance to free movement when the rod is ro
a screw 3 to a rod 2 which is free to rotate within 25 tating. The adjustable bearing 6 provides means
bearings ‘i and I 2a with the rotation of the coil
as the temperature changes. Attached to the
rod 2 is another bi-metallic coil 4 wound in such
of centralising the rod 2 within the hole through
the casing at 213 and ensures that the said hole
can be of the necessary minimum diameter to
a marmer that on being subjected to heat it
‘prevent friction against the rod 2 and/or pene
rotates in a clockwise direction, i. e., in the oppo 30 tration of dust or insect life into the interior
site direction to that of the coil l, with its free
chamber in which the coil £5 and the contacts
end 5 acting as an electric contact, and so ar
are housed.
ranged that it is shielded by the walls of the
The adjusting disc is provided with calibrated
chamber as from direct exposure to the atmos
divisions by means of which the tension of the
phere in order to prevent the coil 4 from being 35 movable contact 5 against the ?xed contact 9 is
immediately affected by any rapid rise in tem
adjustable for the purpose of providing predeter
perature, such as would be occasioned by an out
mination of the degree of minimum rapid rise in
break of ?re. This compensating effect makes
temperature necessary to free the contact 5 from
the device give an alarm on a rapid rise in tem
engagement with the contact 9. Such divisions
perature, but prevents it from giving an alarm in 40 are calibrated to provide easy means of visible
normal slow changes in atmospheric temperature.
adjustment of the thermostat without resort to
The free end of the second bi-metallic coil
trial and error methods of adjustment, and also
which acts as a movable contact is set between
to provide a ready means of checking adjustment.
two ?xed immovable contacts 9 and I8 and so
that it will make contact with one or other of
these ?xed contacts in accordance with certain
conditions of temperature, as will be mentioned
later. In its normal position corresponding to
ordinary atmospheric conditions, it will be in
engagement with the contact 9 under tension
according to the position of the adjusting wheel
l5, which is of insulating material, the casing I6
being also of insulating material. When the
thermostat is subjected to a rapid increase of
temperature, the coil I, which is exposed, rotates
in an anti-clockwise direction causing the rod 2
and the coil 4 to rotate in the same direction and
the contact 5 to release its tension against the '
contact 9 and break away from engagement
therewith, thus opening a normally closed electric
circuit. Further rapid heating causes the contact
5 to move over to engagement with the contact
A fusible link i6 connected at one end to a ter
minal plate 23 and at the other end to a spindle
14, forms part of the electrical circuit which can
be traced as follows: From the terminal plate 9a
to the ?xed contact 9, movable contact 5, bi-metal
coil 4, rod 2 to the screw 3, bi-metal coil I, screw
I 3, rod I d, fuse l8, terminal plate 23. The pur
pose of this fusible link inserted within the circuit
is to provide a predetermined maximum tempera
ture at which the above described circuit will
break regardless of whether the rise in tempera
ture is slow or fast, the fuse It? being composed
of two parts of spring metal joined together with
fusible metal and so mounted that upon fusion
one part springs away from the other and makes
a distinct separation and so gives an alarm.
As described above, a slow rise in temperature,
such as a normal rise in atmospheric tempera
ture, will cause the bi-metal coil 4 to rotate in a
I 0, closing a normally open electric circuit. When
contrary direction to the bi-metal coil l and thus
the temperature of both coils again stabilises, the
neutralise the movement of the coil 1 so that no
contact 5 moves back to engagement with the 65 movement of the contact 5 takes place and the
contact 9.
fusible link is provided to detect an abnormal slow
If the thermostat is subjected to a slow rise
rise of temperature before a dangerous tempera
in temperature, such as normal atmospheric
ture is reached, such as might be occasioned by a
changes, both the exposed bi-metal coil and the
smouldering ?re.
shielded bi-metal coil are affected thereby and 70
After the device is assembled, the thermostat
both rotate, but as the shielded coil rotates in an
opposite direction (clockwise) no movement of
the contact 5 takes place, and in this manner the
must ?rst be set at zero position, i. e., when the
contact 5 engages with the ?xed contact 9 without
tension. When the contacts are at this position,
the adjusting wheel I 5 on the rod Hl'is turned
thermostat compensates to slow changes of tem
perature and remains equally sensitive to a rapid 75 until the arrow pointers 22 (indicating zero posi
2,411,093
5
6
tion) are in line with the bottom of the projec
tions 25 on the wall of the casing, and in this
ature the free end of the second coil will break
away from engagement with said normally closed
position the adjusting wheel is secured to the
circuit contact and engage with said normally
rod M by a screw {5a. The thermostat is now
open circuit contact and thereby give an alarm
ready for adjustment.
O1 of ?re.
The calibrated divisions 2! on the adjusting
2. A ?re detecting thermostat, comprising a
wheel correspond to and measure the extent of
rotatable rod, a bi»metallic ?re-detector coil
rotation of the lei-metal coil I for a given number
?xed at one end and secured to said rod at the
of degrees of heat applied to the said coil.
other end in such a manner as to rotate the rod
When the adjusting wheel is set at zero posi 10 in one direction on being subjected to» heat, a
tion, as described, any rotation of the adjusting
second bi-metallic coil rotatable with the rod
wheel rotates contact 5 in the same direction.
For the purposes of detecting a rapid rise in
and having a free end constituting a moving con
tact, such second bi-metallic coil being arranged
temperature, the adjusting wheel is rotated in
so as to rotate itself upon being subjected to
the direction in which the moving contact 5 is 15 heat but in an opposite direction to the ?rst men
brought into tension engagement with the con
tioned coil.
tact 5 and then looked at the desired position
3. A ?re detecting thermostat as claimed in
by the screw 65!). For example, if it is desired
to set the thermostat so that the contact 5 will
break away from the contact 9 when it is sub
jected to a minimum rapid rise in temperature
of say twenty degrees, the adjusting wheel is
turned (in the direction of the contact 9) so that
the arrow positions are, say, four divisions away
claim 1, provided with an adjusting wheel, a sec
ond rod connecting the ?rst mentioned coil to
said adjusting wheel, such adjusting wheel be
ing capable of being rotated and thereby to r0
tate the ?rst mentioned coil, and then secured
in position for the purpose of adjusting and de
termining the sensitivity or" the device to a rapid
rise of temperature, the second mentioned rod
and wheel being insulated from the ?rst men
from zero position and locked in that position.
It will be readily understood that the actual
rise in temperature required to operate the ther
tioned rod in order to ensure that the electric
mostat at any predetermined setting is deter
current will be carried through the coils.
mined by the speed of the rise in temperature,
4. A ?re detecting thermostat as claimed in
this being due to the compensating effect of the 30 claim 1, provided with an adjusting wheel, a sec
coil 4 and, therefore, a minimum rapid rise in
ond rod connecting the ?rst mentioned coil to
temperature is emphasized. The greater the
said adjusting wheel, such adjusting wheel be
speed of the rise in temperature, the lower the
ing capable of being rotated and thereby to ro~
operating temperature within the minimum rise
tate the ?rst mentioned coil, and then secured
35 in position for the purpose of adjusting and de
of temperature determined by the setting.
By insulating the rod 2 from the rod lit with
termining the sensitivity of the device to a rapid
an insulating piece 12 (Figure 3), both coils are
rise of temperature, the second rod and wheel
caused to carry all electric current from the
being insulated from the ?rst mentioned rod in
terminal plate 25 to the contact 9 and this, be
order to ensure that theelectric current will be
ing part of a closed circuit, causes both coils to 40 carried through the coils, and means for making
be under automatic continuity test so that should
visible measured adjustments for ?xing a min
either coil break as a result of corrosion or other
imum limit to the rapid rise of temperature at
cause, an alarm is given.
which the apparatus will function.
The ring 25 is used to secure the bi-metal coil
5. A fire detecting thermostat as claimed in
I to the actuating rod 2 by means of the screw
claim 2, provided with an adjusting Wheel, a sec
3, while another ring 26 is used to secure the bi
ond rod connecting the ?rst mentioned coil to
metal coil l to the spindle M, and in both cases
said adjusting wheel, such adjusting wheel be
to complete and maintain the electrical circuit
ing capable of being rotated and thereby to re
by means of the bi-metal coil i.
tate the ?rst mentioned coil, and then secured
A grub screw 2'5 secures the bush 26 to the 50 in position for the purpose of adjusting and de
spindle M, while securing screws 23 are shown
termining the sensitivity of the device to a rapid
at various points and a screw 29 or rivet connects
rise of temperature, the second rod and wheel
the bi-metal coil Ll to the actuating rod 2. Stand
being insulated from the ?rst mentioned rod in
ard terminal connections are shown at 33. The
order to ensure that the electric current will be
coil I is protected over its length by protection
carried through the coils, and means for making
rods 32 mounted in brackets or the like 3!, whilst
visible measured adjustments for ?xing a min
the end covers 8 and iii are secured to the pro
imum limit to the rapid rise of temperature at
tection rod brackets 3! through the casing it
which the apparatus ‘will function, and having
of insulating material by screws 33, such end cov
means for ?xing a maximum limit of tempera
ers 8 and it‘ also being of insulating material.
What I claim is:
l. A ?re detecting thermostat comprising a
ture beyond which limit the apparatus will not
compensate.
support having conical recesses, a rod, a ?rst
bi-metaliic coil open to the atmosphere and
tending to rotate the rod in one direction on
being subjected to heat, an enclosure, a second
bi-metallic coil encased from the atmosphere
Within said enclosure and tending to rotate said
rod in the opposite direction on being subjected
to heat, a normally closed circuit contact nor
mally engaged by the free end of the second coil,
a normally opened circuit contact, both ends of
the rod being conical and mounted in said coni
cal recesses so that on the movement of the ?rst
mentioned coil by a sudden increase of temper
6. A ?re detecting thermostat as claimed in
claim 2, provided with an adjusting wheel, a sec
ond rod connec ing the ?rst mentioned coil to
said adjusting wheel, such adjusting Wheel be
ing capable of being rotated and thereby to ro
tate the ?rst mentioned coil, and then secured
in position for the purpose of adjusting and de
termining the sensitivity or" the device to a rapid
rise of temperature, the second rod and. wheel
being insulatedfrom the ?rst mentioned rod in
order to ensure that the electric current will be
carried through the coils, means for making vis
ible adjustments for ?xing a minimum limit to
75 the rapid rise of temperature at which the ap
2,411,093
7
8
paratus will function, means for ?xing a max
imum limit of temperature beyond which limit
paratus will function, means for ?xing a max
the apparatus will not compensate, bearings for
the ?rst rod, and means for adjusting the bear
ings and securing the alignment of the ?rst rod
thereon.
7. A ?re detecting thermostat as claimed in
claim 2, provided with an adjusting wheel, a sec
imum limit of temperature beyond which limit
the apparatus will not compensate, bearings for
the ?rst rod, means for adjusting the bearings
and securing the alignment of the ?rst rod
thereon, and the coils forming part of the cir
cuit.
8. A ?re detecting thermostat as claimed in
claim 2, the coils being under automatic electrical
ond‘rod connecting the ?rst mentioned coil to
said adjusting 'wheel, such adjusting wheel be 10 test by reason of the insulating arrangement.
9. A ?re detecting thermostat as claimed in
ing capable of being rotated and thereby to ro
claim 2, in which the adjustment is made by ro
tate the ?rst mentioned coil, and then secured
tating the coil.
in position for the purpose of adjusting and de
10. A ?re detecting thermostat as claimed in
termining the sensitivity of the device to a rapid
rise of temperature, the second rod and wheel 15 claim 1, means for adjusting the sensitivity of the
device by setting the tension of the contacts in
being insulated from the ?rst mentioned rod in
order to ensure that the electric current will be
the normally closed circuit, by means of a cali- ‘
brated device.
carried through the coils, means for making vis
RONALD PURVIS JAMESON.
ible adjustments for ?xing a minimum limit to
the rapid rise of temperature at which the ap 20
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