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Патент USA US2411642

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NOV. 26,
c_ K_ STRQBEL
' 2,411,642
SAFETY CONTROL APPARATUS FOR FUEL BURNERS
Filed March 23, 1945
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Patented Nov‘. 2c, 1946 _
I
‘
2,411,642.”
um'rso s res PATENT ’ rrlc
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'
‘
2,411,642
ssrs'rv’cou'mos
* Business
APPARATUSFOR
,
iL‘harles K. Stro‘bei, Pittsburgh, Pa., assignor to
Robertshaw Thermostat Company, Youngwoou,
Pa, a corporation of Pennsylvania
‘ Application March 23, 1945, Serial No. 584,218
5 Claims. (Cl. 158-1171)
This invention relates to safety'control sys
tems for fuel burners and,‘mcre particularly, to
electrically operated controls'thereior.
Safety control systems of the electrically oper~
Other objects and advantages will become ap
parent from the following description taken in
connection with the accompanying drawing,
wherein is shown a. schematic view of a safety
ated type may be arranged to include a starting
control apparatus for a gaseous fuel burner em
period during which the circuit conditions are
bodying the invention.
'
‘
such that su?icieht current is supplied to the fuel
Referring more particularly to'the drawing, a,
controlling means to actuate it to a position in
main fuel burner is is supplied with gaseous fuel
which fuel is supplied to the burner. Thereafter,
by a main fuel pipe
The fuel supply in the
the normal running period is initiated and the iii pipe ‘52 is controlled by a main valve is which,
circuit conditions automatically reduce the cur
in this instance, is adapted; for manual operation
rent supplied to the iuel controlling means to
but which may be'arrariged for thermostatic op
holding value. The fuel controlling means does
'eration if desired. interposed in the fuel supply
not move from the fuel supply position providing
pipe ‘l 52 between the main valve ii.‘- and the burner
the burner is producing a ?ame. However, sub
is is an electromagnetic or solenoid gas valve ill‘
sequent extinguishiment of the burner
will
of any known type which may" be arranged,‘ as in
result in a prompt response of the circuit elem
this instance, to be opeuesi when current of sum
ments to further reduce the current
to
cient energizing- value s cplied to the solenoid
the fuel controlling means below the
H
and closed by gravity more. a reduction of the
value. This causes the fuel contra
3' me
to
current value thereto below holding value.
assume a position in which
"'
rely
the
A pilot burner it is provided for
burner is prevented.
main burner iii and is supplied wit
a
The means for cletei‘uii
WEE t
conduit
under control
2s connected
or the main
to thevalve
mai
be
controlling means remains i
ting position may taise the‘ i“
haul-181:. re“
> understood,
could be dispensed
however,v/i'thatv
sistance element locatecl'
burner flame and arranged
the
essential principles of
ihe
eluded for the purpose of
relation
‘I
and
at the main burner at"
various elements of the system in their relative
positions of 1186,
Electric current for the o"
controlling means is couuectec, '
presence or abse
scribed and claimed
my copeum ‘
Serial No, 436,032, filed February
Patent
protective
No. device
2,379,114;
is therefore
granted seem
to
ratus
the isprimary
suppliedofby
a trau
the '
event that the thermal ‘resistance
comes open-circuiteai.
prior L
able in such apparatus ‘
cutout was employed to internist the »
current
to terminate
cease,the
when
sushi,
main switch for the elect“
l 1,
transformer 23 may he is
merit.
of, an open
However,
circiut
this
in cutout
the thermal
was cosh
valve lil with suitable ' ‘
circuit to receive e"
'
closure of the main 3
if} is actuated to open
during the starting as
operate. Consequently,
prior disclosure to prcvi
The main switch of .
connected by a wire
out having a combined
secondary of the‘trausioE
avoid undesired int‘ i
minal of the main sv "
ing the startihga
by a Wire it to one te
an object of the present iriverr
‘
to
the ocerat’
e other terl
theofcoil
a control
32 is connectecl
relay by
wire s» to o -.e
tion A of a parallel mesh which is connected
the required protect
type described without
cutout.
the other terminal of
secondary of the trans»
former 2:3 by a wire
The main switch of valve
the safety features of the prior invention while
is and the operating coil
arethus in series
substituting the improved arrangement of this
circuit
One
branch
with
the
of
secondary
the
narallel
of
transformer
mesh
consists of a
invention
55
Another object of
i
" n is
retain all
2,411,642
3
the ?rst resistor 48 when the timing element is
thermal resistor 38 having a preselected tem
perature coei?cient of resistance and located in
proximity of the flame from the pilot burner I8.
closed.
The thermal resistor 38 is preferably in the form ,
of a coil of Wire of material having normally a
relatively low resistance and a positive tempera
ture cocflicient of resistance. While being ther
mally responsive to the passage of current there
through the thermal resistor 38 is primarily re
sponsive to the heat of the ?ame of the pilot
burner 18. It will be apparent that other types
of temperature responsive, flame sensitive ele
ments or so-called ballast resistors could be sub-‘
stituted for the thermally responsive resistor dis
closed herein. The branch consisting of the
_
parent, therefore, that in addition to opening and
closing the parallel circuit for the cutout 48, the
timing element 88 will simultaneously open and
close the circuit of the igniter 88. Should the
igniter 88 become. burnt‘out or otherwise dam
1.0
aged 50 that an open circuit occurs therein, then
means provided herein may be operated man
ually to complete the circuit of the igniter. This
vmeans takes the form of a manually operated
switch 18 which is normally held open by a spring
18 and is connected in parallel circuit with the
igniter 88. The connection may be traced by way
thermal resistor 38 is connected at one end by a
of a Wire 88 connected at one end to the wire 12
and at the other end to one terminal of the switch
wire 40 to the junction A and at the other end
by a wire 42 to the opposite junction B of the
parallel mesh.
'
The second constant resistor serves to adjust
the current value to the igniter 88. It is ap
18, and by a wire 82 extending‘from the other
.
terminal of the switch '_|8 to ‘the wire 10. A
The other branch of the parallel mesh consists 20
suitable constant resistor 84 may be included in
of an operating coil 44 for the electromagnetic
the wire 88 in series with the switch 18 to com
valve 16, a ?rst constant resistor 48 and a cutout
pensate for the loss of the resistance value of
48. These elements are connected in series cir
the igniter 88 should it become open-circuited.
cuit in the other branch by a wire 50 connecting
The operating coil 44 of the electromagnetic
25
one terminal of the coil 44 to wire 38 at junction
valve I8 is ‘arranged to be shortécircuited for a
A‘, a wire 52 connecting the opposite terminal of
predetermined period of time during the initial
coil 44 to one end of the resistor 48, a wire 54
or starting period in order to permit the igniter
connecting the opposite end of the resistor 48 to
88 to produce a flame at the pilot burner l8 be
one terminal of the cutout 48, and a wire 58 con
30 fore the main burner i8 is suppliedwith fuel.
necting the opposite terminal of the cutout 48
The short-circuit for the coil 44 is established
to wire 42 at junction B of the parallel mesh.
by switching means in the form of a second tim
As previously indicated herein, the cutout 48
is of the simple renewable type and will operate
to interrupt the 'flow of current to the coil 44
ing element 88 in the control relay 30. As in
the case of the timing element 88 the second tim
ing element 88 may be of the mercury tube type
and arranged to open from its initially closed‘
position after a predetermined time delay follow
ing energization of the coil 32 but after a delay
of the electromagnetic valve I8 upon the oc
currence of an open circuit in'th'e thermal re
sistor 38. As will appear hereinafter, no time
delay or other special construction is required
in connection with the cutout 48 due to the cir
cuit arrangements of this invention. The ?rst
constant resistor 48 serves to adjust the current
value to the cutout'48 so that during the starting
period of. only six seconds. ~ Preferably, both the
40 timing elements 80 and 88 close instantaneouly
, period it is less than the steady operating value
of the current supplied thereto and is of suitable
resistance value for this purpose. It is apparent
that during the starting period of the burner if
current of su?icient value to actuate the electro
magnetic valve l8 to open position is supplied to
the coil 44 thereof, then the cutout 48 which is
in series circuit with the coil 44 would also re
ceive sufiiciently large current to cause it to op
erate and open the circuit of the electromagnetic
valve I8. Means are provided in this invention
to prevent this undesired operation of the cutout ;
48 as will now be described.
The control relay 38 embodies switching means
upon deenergization of the coil 32, it being noted,
' however, that it is not essential that the timing
element 80 have an instantaneous closing action
as long as it assumes ‘a closed position before
reopening of the timing element 88. Thus, where
such ‘a short time delay as six seconds in estab
lished for the timing element 88, then the timing
element 60 would almost necessarily have an in
stantaneous action also. A wire 88 connected.
one electrode of the timing element 88 to wire 48
and a wire 90 connects the other electrode to
the common wire 84.
‘The circuit from junction B of the parallel mesh
to the transformer secondary is completed by a
wire 92 connecting one end of a variable resistor
94 to junction B and a wire 98 connecting the
other'end of the resistor 94 to the wire 28. The
including a timing element 80 which is initially
variable resistor is similar to the thermal re
closed and has a speci?ed time delay of eighteen
sistor 38 in having a positive temperature coe?l
seconds before opening. Any suitably type of 60 cient of resistance and normal low resistance but‘
timing element may be used and, in this instance,
is responsive only to the heating effect of the
the mercury tube arrangement well known to
current flow therein. The resistor accelerates
those skilled in the art is preferred. One elec
the closing of the electromagnetic valve i8 as
trode of the timing element 88 is connected by
disclosed in Patent No. 2,366,774 and is termed
a wire 82 and a common wire 84 of the relay to
a valve control resistor.
the wire 52.
The operation of the device is as follows:
Manual or thermostatic closing of the main.
The other electrode of the timing
element 88 is connected by a wire 10 to one end
of an electric resistance igniter 88 for the pilot
burner. the opposite end of which is connected
by a wire'12 to one end of a second constant re
sistor 88. The opposite end of the second resistor
88 is connected by a wire 14 to junction B of the
parallel mesh. Thus, timing element 80, igniter
'
switch of valve I4 e?ects opening of this valve,
as described, and permits fuel to ?ow in the main
fuel pipe‘ 12 as far as the electromagnetic valve
I8 which is initially closed. Electric energy from
the transformer 24 is conducted from the second
ary thereof by the wire 38 to junction A of the '
parallel mesh and by the wire 28, main switch
88 and resistor 88 are in series circuit and jointly
establish a parallel circuit with cutout ‘a and 75 of valve I4, wire 28, wire 98, valve control resistor
53,411,6d2
84 and wire 32 to junction B of the parallel
mesh. Although the operating coil 32 of the con—
provided by the cutout 118 is required only dur
trol relay 3!) is energized by the connection of
one terminal thereof to the junction A by wire
while they thermal resistor 38 is controlling the
electromagnetic valve i6, and the parallel cir-v
34 and the opposite terminal to the main switch
by wire 28, the delay periods of the timing ele
ments 6B and 86 maintain the circuits which
they are connected closed. Consequently, the
coil M of the electromagnetic valve i6 remains
short-circuited for six seconds by the shorter time
delay element 85 and no fuel is supplied to the
main burner to during the starting period.
The ignitei' til is energized through the circuit
from transformer secondary, wire as, main switch
of valve l5, wire 96, valve control resistor 94;
wire M, junction B, wire '14, second resistor 68‘
ing the running period oi’ the burner, that is,
cuit or shunt provided for the cutout 48 during
the starting period does not interfere with its
essential function.
The circuit arrangement described and shown
herein permits considerable variation in the value
' 10 of the respective resistances without detracting
from the desired operating characteristics.
Moreover, while the preferred arrangement of
parts has been illustrated and described it will‘
be apparent that the apparatus is not limited to
this particular embodiment but various changes
may be made within the scope of the appended
claims.
wire 12, igniter 555, wire
tirning element 60,
wires so and 9R3, timing element 86, wire88,
I claim:
‘ junction A, and wire 85 ‘back to the transformer
1. A safety control system for fuel burners hav
24. During this starting period, the fuel flow—
ing from the "pilot burner i3 is ignited by the
igniter 65 but this period is too short for the
thermal resistor 38 to become appreciably heated
by the pilot burner flame and increase its rela
ing a source of electrical energy, comprising elec
trically operable means movable between posi
tions for controlling the supply of fuel to a fuel
burner, a thermal resistor having a preselected
temperature coefficient of resistance located in
tivelylovv resistance. At the end of the shorter
time delay period the timing element lit opens
and removes the short-circuit from the operat
ing coil lid of the electromagnetic valve l6 and
this valve is actuated to open position. it will be
observed that the coil Q4 thus receives current
proximity of the burner so as to be heated by‘
the ?ame produced by the burner and connected
in parallel circuit with said controlling means for
varying the energy value supplied thereto upon
variations in the resistance of said thermal re
sistor due to the presence or absence of said
flame, current responsive lmeans in said circuit
and operative for causing movement of said con
controlling means to a position in which said
fuel supply is prevented upon the occurrence of
an open circuit in said thermal resistor, and
‘means electrically connected to said current re
sponsive means and effective for preventing op
eration thereof for a predetermined period dur
ing which said thermal resistor has time to be
come heated, said last means including a timing
element operable upon expiration of said period
for rendering said last means ineffective.
of su?lcient value to cause opening of the elec
tromagnetic valve l5 although the parallel circuit
established by the thermal resistor 38 across junc
tions A and B of the parallel mesh still exists.
Such forced pick-up of the electromagnetic valve
16 is due to the combined resistance values of
. the valve control resistor 9t, second resistor 68
and igniter lid being low enough for such pick--up
to occur. Consequently, fuel then flows through
the fuel pipe l2 to the main burner it! where it
is ignited by the pilot burner l8.
‘
Upon the expiration of the longer time delay
period of the timing element 60 which, as stated,
may be eighteen seconds, the circuit of the ig
niter 66 is discontinued causing deenergization
2. A safety control system for fuel burners hav- .
ing a source of electrical energy, comprising elec
~ trically operable means for controlling the sup
ply of fuel to a burner and being actuable to a
thereof. In addition, the parallel circuit is re
moved from the cutout E8 and first resistor 46
fuel supplying position when energy of sufficient
by this opening operation of the timing element
value is supplied thereto and being movable to a
60. The total circuit resistance is thus increased
su?lciently to reduce the value of the current to
the operating coil 4d of the electromagnetic
valve i6 and cause this valve to close, unless the
thermal resistor 38 is heated by the flame from
the pilot burner i8 and its resistance increased
sui?ciently to compensate for this increase in to
tal circuit resistance. if at any time during the
operation of the apparatus the flame of the pilot
burner l 8 becomes extinguished, then the thermal
position for preventing said fuel supply when
energy of insu?lcient value is supplied thereto,
resistor 38 will cool and its resistance be de
creased sumciently to render the value of the
current to the valve coil-44 insumcient to main
tain the electromagnetic valve it in open posi
- tion, whereupon this valve will close to terminate
the supply of fuel to the main burner to.
a thermal resistor having a preselected tempera
ture coei?cient of resistance located in proximity
of the burner so as to be heated by the flame
produced by the burner and connected in a par
allel circuit with said controlling means for vary
ing the energy value supplied thereto upon varia
tions in the resistance of said thermal resistor
due to the presence or absence of said flame,
current responsive means in said circuit and oper
tin
ative for causing movement of said controlling
means from fuel supplying to fuel supply pre
venting position upon the occurrence of an open
circuit in said thermal resistor, and means elec
trically connected to said current responsive
It is apparent that the temperature‘ condition
' means and‘ effective for preventing operation
of the thermal resistor
does not in?uence the
actuation of the electromagnetic valve l8 to open
thereof for a predetermined period during which
said thermal resistor has time to become heated,
position, but does control the holding and ‘re
said last means including a timing element oper
lease of the valve. Should this thermal resistor
38 become open-circulted and. discontinue its
branch of the parallel mesh, then the provision
of the cutout
which would consequently re
ceivecurrent of operating value, serves to open
the circuit of the operating coil 13-5 in the other
said last means ine?ective and increasing the to
tal circuit resistance to cause energy of said in
su?icient value to be supplied to said controlling
means unless said thermal resistor has varied due
branch of the mesh. Hence, this safety feature
3. A safety control system for fuel burners hav~
able upon expiration of said period for rendering '
to the presence of the burner ?ame.
-
-
.
_
2,411,642
,ing‘a source of electrical energy, comprising elec
trically operable means for controlling the sup
ply of fuel to a burner and being actuable to a
in series circuit with said controlling means for
causing movement thereof from fuel supplying to
fuel supply preventing position upon the occur
rence of an open circuit in said thermal resistor,
said current responsive means being short-cir
value is supplied thereto and being movable to a
cuited by said timing element and igniter for said
position for preventing said fuel supply when
predetermined period, and means cooperable with
energy of insufficient value is supplied thereto,
said current responsive means for establishing a
a thermal resistor having a preselected tempera
second circuit for said controlling means upon
ture coef?cient of resistance located in proximity
of the burner so as to be heated by the flame 10 operation of said timing element to discontinue
said short-circuit and increase the total circuit
produced by the burner and connected in a par
resistance to cause energy of said insu?lcient ‘
allel circuit with said controlling means for vary
value to be supplied to said controlling means
ing the energy value supplied thereto upon varia
unless said thermal resistor has varied due to the
tions in the resistance of said thermal resistor
due to the presence or absence of said ?ame, cur 15 presence of the burner ?ame.
_ 5. A safety control and ignition system for fuel
rent responsive means in series circuit with said
burners having a source of electrical energy, com
controlling means and operable for causing move
prising a parallel mesh circuit connected to said
ment thereof from fuel supplying to fuel supply
source, a thermal resistor in one branch of said
preventing position upon the occurrence of an
open circuit in said thermal resistor, and means 20 mesh having a preselected temperature coefiicient
of resistance and located in proximity of a burner
electrically connected to said current responsive
?ame for varying in resistance due to the presq
means for short-circuiting the same for a pre
ence or absence of said flame, electrically oper
determined period during which said thermal re
able means in another branch of said mesh for
sistor has time to become heated, said last means
including a timing element operable upon ex 25 controlling the burner fuel supply and being
actuable to a fuel supplying position when energy
piration of said period for discontinuing the said
of sumcient value is supplied to said controlling
short-circuit and increasing the total circuit re
means and being movable to a position for pre
sistance to cause energy of said insu?icient value
venting said fuel supply when energy of insu?l
to be supplied to said controlling means unless
said thermal resistor has varied due to the pres 30 cient value is supplied thereto, a cutout operative
to open saidother branch and cause movement
ence of the burner ?ame.
of said controlling means from fuel supply to fuel
4. A safety control and ignition system for fuel
' fuel supplying position when energy of sufficient
supply preventing position upon the occurrence
burners having a source of electrical energy, com
of an open circuit in said one branch, a ?rst '
prising electrically operable means for control
ling the supply of fuel to a burner and being 35 resistor in said other branch for adjusting 'the
energy value to said cutout, an electric igniter
actuable to a fuel supplying position when energy
adapted when energized to ignite the fuel and
of sufficient value is supplied thereto and being
cause the same to produce a, ?ame at the burner,
movable to a position for preventing said fuel
a second resistor for adjusting the energy value
supply when energy of insuf?cient value is sup
plied thereto, an electric igniter adapted when 40 to said ‘igniter, and a control device having a
timing element for connecting said igniter and
energized to ignite the fuel and cause the same ,
second resistor in parallel circuit with said cutout
to produce a ?ame at the burner, means estab
and ?rst resistor for a predetermined period in
lishing a ?rst circuit for supplying energy of said
which said thermal resistor has time to become
sufficient value from the source to said control
heated and cause the supply of energy to said
ling means and including said controlling means,
other branch to decrease to a value insu?icient to
said igniter, and a control device having a timing
operate said cutout, said timing ‘element being I
element operable after a predetermined period
operable upon expiration of said period for elecfor electrically disconnecting said igniter from
selected temperature coe?icient of resistance
tically discounting said igniter and said second
resistor and thereby increasing the total circuit
located in proximity of the burner so as to be
resistance to causeenergy of said insu?lcient "
said circuit, a thermal resistor having a pre
heated by the ?ame produced by the burner and‘
electrically connected in parallel with said ?rst
circuit for varying the energy value supplied to
value to be supplied to said controlling means
unless said thermal resistor has increased in
resistance due to the presence of said burner
said controlling means upon variations in the
?ame.
. resistance of said resistor due to'the presence or
absence of said ?ame, current responsive means
'
CHARLES K. STROBEL.
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