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1'5, 1-946. _’ =
' B, w. JONES f
' 7 . 2,409,492; f
THERMAL TIllE SEQUENCING CONTROL SYSTEM
I Filed ‘March 7, 1944
LI
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Inventor“: 'v.
Benjamin W. Jones,
byJv-WmW/M '
Has Attorney ~ '
2,409,492
UNITED STATES PATENT OFFICE.
Patented Oct. 15, 1946
2,409,492
THERMAL TIME SEQUENCING CONTROL
SYSTEM
Benjamin W. Jones, Schenectady, N. Y., assignor
to General Electric Company, a corporation of
New York
Application March 7, 1944, Serial No. 525,445
20 Claims. (Cl. 158-—28)
1
The invention relates to control systems, par
ticularly sequencing control systems for operat
ing ‘oil burners or other condition regulating de
vices requiring a sequential time and condition
responsive operation control.
One of the objects is to provide an improved
thermal time sequencing control system that is
capable of providing repeated timed starting op
2
der the control of a thermal timer only for a lim
ited initial period during the cooling time delay
‘thereof, and having the relay holding winding
.then energized in response to the occurrence of
a predetermined condition during the limited ef
fective pickup energizing period of the pickup
winding to supplement the partial energization of
the pickup winding that is controlled by the mas‘
ter switch. Such improved sequential relay en
ited cooling period under the automatic control 10 ergization control system is of particular advan
erations of a burner or other device during a lim
of a master controller responsive to a predeter
mined condition, such as temperature, pressure
or the like, and of automatically continuing op~
eration of the device only in case a resultant op
erating condition, such as combustion or the
like, is successfully established during one of the
tage for operating a burner since it enables a
thermal responsive control device that is heated
upon the successful establishment of combustion
by the burner, such, for example, as a thermo
electric generator, to energize the holding Wind
ing of the operation control relay and thereby
continue operation of the burner under the joint
limited cooling timed starting operations.
control of the master switch and the thermo
A particular object is to provide an improved
electric generator after the operation control
time and condition responsive sequencing control
system utilizing only the initial part of the cool 20 relay has been temporarily picked up during the
initial part of the cooling period of the thermal
ing time delay of an electrically heated thermal
timer to insure more accurate timing of each trial
timer.
operation interval since such cooling time is not
only independent of variable voltage conditions
Further objects and advantages of the present
invention will appear in the following description
of the accompanying drawing in which the single
?gure is a schematic circuit diagram of an auto
matic oil burner sequential control system em
bodying the improvements of the present inven
but also is influenced the least by any'normal .
ambient temperature variation.
‘Another object is to provide an improved
sequencing control system wherein repeated pe
riodic operations of a thermal timer alternately
energize a timer heater and an electroresponsive
operation control device in such a way as to
maintain the control device energized only dur
ing the initial part of the cooling period of the
thermal timer and to maintain both the heater
and the control device deenergized during the
subsequent part of the cooling period, and where
in a separate thermal lockout timer having a
relatively long time delay produces a safety lock
out only in case a predetermined condition is not
established during a limited number of repeated
timed energizations of, the operation control de
tion in a preferred form.
The oil burner It may be of any usual type
having a driving motor, indicated schematically
by the motor energizing winding l l, for operating
a blower l2 and an oil pump I3.
The blower l2
supplies air underpressure to the nozzle air tube
15 and the oil pump l3 supplies oil under pres
sure, when the electromagnetic oil ?ow control
valve I5 is energized, to the oil atomizing nozzle
H. An ignition transformer It! produces an ig
nition are between the electrodes H) to ignite the
atomized oil projected from the nozzle l1 and
thereby establish combustion in the combustion
vice.
chamber 2E1 of a furnace or other heating device.
A further object is to provide an electrorespon
sive control device having an incremental pick
Operation of the oil burner 10 is always under
up energization and an incremental holding en
ergization with a thermal timer for limting the
incremental pickup energization period thereof
and with an improved condition responsive en
the control of a master control switch 22 which
may be responsive to a condition dependent
upon the operation of the burner ll], such as
room temperature or the like.
.
In accordance with the present invention, the
ergizing means for providing the incremental
room thermostat 22 operates ?rst to provide a
holding energization therefor independently of I
the thermal timer when a predetermined condi
partial energization of the electroresponsive
burner control relay 36 and then, through the
tion is successfully established during the limited
pickup period of energization of the device.
agency of the periodic thermal timer 23, tem-'
porarily provides an eiiective pickup energiza
A more speci?c object is to provide an improved
sequential control system having a unidirectional
tion of relay 30 to start operation of the oil burn
er iii. and continue such operation only for a lim
current responsive operation control relay pro
vided with magnetically interrelated pickup and
holding windings and having the pickup winding
ited initial period during the cooling of the ther
mal timer 23 in case combustion is not estab
lished.
only partially energized under the control of a
A shown, the thermal timer 23 is provided with
master switch and then effectively energized un 60 a thermal responsive operation control member
2,409,492
4
24 of the bimetal type which is normally bi sed
when cool into attracted relation with the snap
action permanent magnet 23 so as to maintain
the timing heater circuit control contacts 25
?rmly in engagement during the predetermined
33 when power is supplied to the former from the
alternating current supply lines LI, L2, and to
the latter from the thermoelectric generator
A control lockout timing device 48 is provided,
period of heating of the bimetal member so re
and may be of the solder pot type, as shown, or
other suitable type that provides a relatively
quired to release the member 24 from the magnet
and thermally bias member 24 to close the alter
native circuit controlling contacts
The ther
long timing period compared to the heating and
cooling time of the periodic thermal timer 23.
As shown, the lookout timer 4-3 is provided with
mal timing element 24 operates with a snap ac
tion to open the contacts 28 and close the two
contacts 21 after the electric heater 23 is ener~
gized to provide a limited period of heating of the
a switch element 4| that is normally biased out
'of contact with the cooperating switch element
42 but is mechanically latched in contact there
with by engagement of element Iii with the teeth
of the ratchet wheel 43. The shaft M carrying
the ratchet wheel 43 is normally held stationary
by the solder 45 in the pot 45 as long as the solder
is solid. The electric heater 4? is provided for
heating the pct 35 to soften the solder sufficiently
to permit the ratchet wheel 43 to rotate and
20 thereby permit switch member ‘33 to disengage
the ratchet 43 in accordance with its bias and
thereby move out of contact with. switch ele~
ment d2.
thermal timing element 24. Since the thermal.
timing element 24 effects the deenergization of
the timer heater 28 by means of contacts 23, the
two contacts 2? can be maintained closed only
during a predetermined initial part of the cooling
predetermined
period, of the thermal
by the snap
responsive
actionelement
produced by
magnet 25 in opening contacts
and closing
contacts 27. As a result, both contacts 23 and
contacts 21 are maintained opened during the
subsequent cooling of the thermal timing member‘
24. When cool, member 24 then returns into at“
tractive relation with magnet 25 and recloscs con
tacts 26. Thus the thermal timer 23 constitut "
a periodic alternative circuit controllingr double
throw switch having a snap action magnet for
extending the heating period thereof and providing a unilateral thermal time delay movement
after an‘ initial limited period of cooling.
The electroresponsive control relay 3b is shown
as of a special double Winding type, having,r a
pickup
both in winding
magnetic3| attractive
and a holding
relation
winding
with the
biased
switch to
operating
operate plunger
the movable
33. The
switch
plunger
contact
33 3i‘!
Operation
When thermostat 22 closes its contacts, the re
lay pickup winding 3! is partially energized
through a circuit including conductor 53, contacts
Fri, 42, conductor Ell, relay winding 3i, conductor
5i, heater 4?, recti?er 33, and current limiting
resistor 39.
But at the same time a periodic
heater energizing circuit is established from the
alternating current supply line L2 through the
thermostat 22, conductor 50, the solder pot switch
members 13!, 42, conductor 5|, relay contacts 34,
35, conductor 52, periodic heater 23, contacts 25,
the periodic thermal timer operatin member 24,
conductors
and 53, to the other alternating
current supply line Ll. In such periodic heater
energizing circuit, the relay contacts
and
tacts 35. Only when the pickup Winding 3| is cl‘ ell) the thermal timer contacts 26 must both be closed
fectively energized can plunger
operate con
to energize heater ‘28. thereby enabling the ther
tact 34 into engagement with the upper contacts
mal timer 23 to provide a partial cooling time de~
36. But the holding winding 32 can thereupon
lay interval subsequent to the cleenergization of
become effective to attract the plunger
with
the relay 30 and prior to the energization of
a. force tending to hold contact 33 in engagement
heater 28 in the periodic time cycle. V‘Jith peri
with contacts 36. As shown, the relay holding
odic heater 2% thus energized, a limited heating
winding 32 is connected to be energized directly
period for the periodic timer operating element
into engagement with the lower cooperating con
from a suitable thermoelectric generator 31 lo~
cated in the combustion chamber 23 so as to be
responsive to the establishment of combustion
therein due to operation of the oil burner H}.
The thermoelectric generator 31' inherently
generates a relatively feeble unidirectional cur~
rent. Consequently, the energizati-on of relay 513
must be specially controlled so that the '
Yale
unidirectional energlzation of holding winding 32
from generator 37 resulting from the establish
ment of combustion in chamber ‘26 can be utilized
effectively in maintaining the plunger wJ
"3 at~
tracted to hold contact 34 in engagement with
the contacts 36. To accomplish this in accord
ance with the present invention, the pickup wind
ing 3| is maintained partially energized with
unidirectional current through the current lim-iting. resistor 39 when thermostat 22 closes its
contacts so as to assist the holding winding 3“!
in maintaining the plunger 33 in the attracted
position after the establishment of combustion
in the chamber 29 during the initial cooling pe~
riod of timing element Ell. The pickup windi
3| is energized with unidirectional cunent
through the agency of the rectifier 3-3 in order
that the cncrgizations provided by both the pick
up Winding 3| and the holding winding 32 may
jointly and cumulatively magnetize the plunger
24 is initiated. This timer heating period con
tinues until the timing element 25 is heated suf
?ciently to overcome the attraction of the per
manent magnet 25 that holds contacts 25 in en~
gagement to extend the heating period and there-
by predetermine the initial cooling period during
which contacts 2? can be maintained closed by
element 24. Thereupon the member 25 operates
with a snap action to separate contact
and
close the two contacts 2?. The separation of
contact 25 deenergizes the periodic heater 23 and
thereby initiates the cooling of the thermal re
sponsive operating element it.
However. both
contacts 2-? are maintained closed for only the
initial limited period during the cooling of mem
tion
ber 24
of that
magnet
is predetermined
25 during the heating
by the holding
period.
The closing of the left-hand. contact 27 short
circuits the current limiting resistor 39 and there
by establishes an effective energization 0;? the
pickup winding 3| of the control relay 38, this
pickup effective energizing circuit extending
from line L2 'hrough the contacts of thermostat
22, conductor 59, the contacts 4|, 42 of the solder
pot timer d9, conductor 53, pickup winding El,
conductor 5'1’, the solder pot heater
recti?er
38, periodic timer contacts 27, conductors
and
54 to the other line Li. Upon the resulting ef~
2,409,492
5
6
fective energization of pickup winding 3 I, plunger
tion of the pickup winding 3| is removed. In each
case, the energization of holding winding 32 by
the thermoelectric generator 31 alone is insuffi
cient to maintain the contact 34in engagement
with contact 36 against the bias thereof to the
33 is picked up and moves contact 34 out of en
gagement with. contact 35 and into engagement
with contacts 36. The engagement of contact
3.4 with contacts 38 establishes an energizing cir- ,
cult for the operating winding I I of the oil burner
operating motor. this burner operating circuit
opposite position. Consequently, when thermo
stat 22 opens its contacts, or the alternating cur
rent voltage fails, relay 30 will disengage contact
34 from contact 36 and thereby deenergize the
relay 4!), conductor EI, contacts 34, 35, conductor 10 burner operating motor I I to stop combustion.
60, the motor winding I I, and thence through
When thermostat 22 again closes its contact,
conductors 58 and 54 to the other supply line LI.
the timer 23 again operates after a heating pe- '
The oil valve I6 is simultaneously energized in
riod to close its contacts 21, thereby short circuit
parallel circuit with the motor winding II.
ing the current limiting resistor 39 to effectively
Likewise, the primary winding of the ignition 15 energize the pickup winding 3I of relay 39 and
transformer I8 is energized in parallel circuit
start operation of the burner In. Now let us as
with the motor winding I I through the right
sume that for some unknown reason combustion
hand contact 21 of the periodic thermal timer
is not successfully established within the ensuing
23 during the initial limited cooling period of the
initial part of the cooling period of the thermal
timing element 24.
20 timer 23. In this case, the periodic timing mem
Thus the motor II starts operation of both the
ber 24 will, after the initial cooling period, dis
extending from line L2 through the contacts of
the thermostat 22, the contacts of the solder pot
blower I2 and the oil pump I3 to discharge a com
bustible oil and air mixture from the burner noz
engage contact 21 and thus terminate the effec
tive energization of the relay pickup winding 3|.
zle I5. At the same time, transformer I8 estab
Relay 30 at once responds in accordance with it's
lishes an are between the electrodes I9 to ignite 25 bias to reclose contacts 35, and at the end of the
the mixture. Under these conditions, combus
tion should normally be established in the cham
ber 20 within the limited period provided by the
cooling of the thermal timing element 24 prior
to the opening of contacts 21.
subsequent cooling period of the timer 33 con
tacts 26 will be reclosed to again establish the
winding 32.
ber 24. During this initial cooling period burner
energizing circuit for the timer heater 28; There
upon heater 28 again heats the periodic timing
element 24 for the heating period required to ef
Assuming that combustion is successfully es
fect snap action thereof to disengage contacts 26
tablished, thermoelectric generator 31 will be
and re-engage contacts 21. Again the pickup
come heated in responseto the establishment of
winding 3I of relay 30 becomes effectively ener
combustion, and thereupon supply a unidirec
gized while heater 28 is deenergized to provide
tional energizing current to the relay holding 35 another limited initial cooling period of the mem
Consequently, before the timing
member 24 has cooled su?iciently to begin the re
turn movement to its biased position in which it
is shown and thereby open both contacts 2?, the
unidirectional energization of holding winding 32
I0 is again operated to attempt to establish com
bustion. In case combustion still is not success
fully established, the periodic timer 23, after the
40 subsequent cooling period is completed, may re
normally becomes effective to assist the continued
peat the alternate energization of heater 28 dur
partial unidirectional ‘energization of the pickup
ing the heating time of element 24 and the ef
winding 3I provided under the control of thermo
fective energization of pickup winding 3| during
stat 22 by means of the energization limiting re
the initial cooling time of element 24. During
sistor 39. The joint magnetizing action of hold~ "A Li each subsequent cooling time delay period both
ing winding 32 and the partial energization of
heater 28 and winding 3| are maintained deen
pickup winding 3I is required to hold plunger
ergized by the timing element 24. This enables
33 in its attracted position and thereby maintain
the subsequent part of the cooling period, as well
contact 34 in engagement with contact 36 inde
as the entire heating period of the thermal timer,
pendently of the control of timer 23 during and 50 to be utilized for timing the interval between the
after the subsequent part of the cooling period
successive attempts to establish combustion.
thereof. In this way, the oil burner operating
However, during each alternate eifective ener
motor II is maintained in operation to continue
gization of the pickup winding 3|, the lockout
combustion in the furnace chamber 20 under the
heater 4‘! also is effectively energized to supply
joint control of both the thermal electric gen
- heat to the solder pot 46. After a limited number
erator 3'! and the master thermostat 22 and also
of repeated energizations of the lookout heater
responsive to voltage failure of the supply lines
41, sufficient heat will be accumulated by the sol
LI,L2.
der pot 46 to soften the solder therein and per
In case for any reason combustion should fail,
mit the ratchet wheel 43 to turn and thereby dis
the output of thermoelectric generator 31 will 60 engage the lockout switch member 4| from the
quickly decrease so that holding winding 32 is
stationary contact 42. This serves to stop all
no longer effectively energized. Under this con
further operation of the burner control system
dition the partial energization of pickup wind"
until the solder pot has cooled and switch mem_
ing 3I alone is not sufficient to magnetically hold
ber M has been manually reset. In this way the
65
the plunger 33 in the attracted position. Hence
improved control system of the present invention
the control relay 38 will respond to open the en
provides repeated attempts to establish combus
ergizing circuit of the burner operating motor I I
tion by operation of the periodic thermal timer
and thereby prevent continued supply of the com~
23 before the lookout thermal timer 4!] will re
bustible vmixture to the combustion chamber
spond to lock out the control.
when combustion fails 'while the thermostat 22 is
What I claim as new and desire to secure by
calling for operation of the burner.
Letters Patent of the United States is:v
If at any time during successful operation of
1. In combination, a pair of heaters, energizing
the burner either the thermostat 22 becomes sat
circuit means including a selective electrorespon
is?ed and opens its contacts or the alternating
sive control device therefor having means ‘biased
current voltage fails, then the partial energiza 75 for energizing one of said heaters while said de
2,409,492
7
8
vice is energized below a predetermined value and
operable to energize the other of said heaters
while said device is energized above said value, a
snap action thermal time switching element
heated by said one heater and connected for de~
energizing said one heater after a heating time
delay and temporarily energizing said device
ther energization of said heaters and said device
control device, energizing control means therefor
including a thermal time delay control element
having a heater under the joint control of said
above said value during the initial part of the
device and said element for operating said ele
under control of said master switch in the con
tinued absence of said condition,
5. In a control system, an electroresponsive
ensuing cooling time delay, and means responsive
ment to deenergize said heater and thereupon
to an operating condition of the other of said 10 temporarily energize said device only during an
heaters for maintaining said device energized
initial part of the cooling period of said time
above said value independently of said time
delay element, and automatic means including a
switching element during and alter the subse~
burner having a ?ame responsive means rendered
quent part of said cooling time delay to maintain
effective under the control of said device during
said other heater energized.
said temporary energization thereof for main
2. In combination, an electric heater, a com
taining said control device energized during and
after the subsequent part of said cooling period.
bustion heater, energizing circuit means for alter
nately operating said heaters including a snap
action thermal time delay switching element
6.121 a control system, an clectroresponsive
control device having energizing circuit means,
energization control means therefor including
means for limiting the energization of said device,
a heating and cooling time control element hav
heated by said electric heater and connected for ‘
deenergizing said electric heater after a heating
time delay and having electrical means tern
porarily controlled thereby during the initial part
of the ensuing cooling time delay period for oper
ing a heate ' under the joint control of said device
and said element for operating said element to
temporarily energize said heater to heat said ele
ment only while said energization limiting means
is effective and to temporarily render said en
ergization limiting means ineffective only during
the ensuing cooling period of said element, and
separate energizing means rendered effective
under the control of said device during said cool
ing period for supplementing the limited ener
gization of said control device after said cooling
period and thereby maintaining said device en
ergized under the joint control of said energiza
tion control means and said separate energizing
ating said combustion heater, and means respon
sive to an operating condition of said combustion
heater for controlling said electrical means to
continue operation of said combustion heater dur~
ing the subsequent part of said cooling time delay
period and after said cooling period.
3. In combination, an electrically operated com~
bustion heater and a pair of electric heaters hav—
ing energizing circuit means, sequential energiza
tion control means therefor including a snap
action thermal time delay switching element
heated by one of said electric heaters and having
electrical means controlled thereby for alternately
deenergizing said one heater after a heating time
means.
7. In a control system, an electroresponsive
device having a control member biased to one
delay and temporarily energizing said combustion
heater and the other of said electric heaters dur
ing the initial part of the ensuing cooling time
delay and maintaining said pair of electric heaters
deenergized during the subsequent part of said
cooling time delay, means responsive to an oper
ating condition of said combustion heater for con
trolling said electrical means to maintain said
combustion heater energized independently of
said time delay element, and thermal means
40 control position and operable to another control
position upon a predetermined energization of
said device, energizing circuit means for par
g:
tially energizing said device, a snap action ther
mal time delay switching element connected for
temporarily effecting said predetermined ener
gization of said device during the cooling of said
element, an electric heater for said element hav
ing an energizing circuit controlled jointly by
cumulatively responsive _to predetermined re
said control member and said switching element
peated energizations of said third heater for ter 50 to energize said heater to heat said element only
minating the repeated sequential cnergization of
while said control device is partially energized,
said three heaters in the continued absence of
said element having means for deenergizing said
said condition.
heater upon a predetermined heating of said ele
4. In combination, three heaters having ener
ment, and automatic energizing means rendered
gizing circuit means, a master control switch 55 effective during said temporary predetermined
therefor having an electroresponsive control
energization of said control device for supple
transfer device interconnected therewith for al
menting said partial energization of said device
ternately energizing a pair of said heaters, a snap
to maintain said control member in said other
action thermal time delay switching element
control position under the joint control of said
heated by one of said pair of heaters and inter~
connected for alternately deenergizing said one
heater after a heating time delay and temporarily
e?’ectively energizing said device and the third
one of said heaters only during the initial part of
partial energizing means and said automatic en
ergizing means.
8. In a control system, an electroresponsive
control device having two complementary ener
gizing windings provided with energizing circuits,
the ensuing cooling time delay and maintaining 65 energizing control means therefor responsive to
said first and third heaters effectively deenergized
one condition and including means for limiting
during the subsequent part of said cooling time
the energization of one of said windings, a snap
delay, means responsive to an operating condition
action thermal time delay switching element cOn~
of the other of said pair of heaters for maintain
nected for temporarily rendering said limiting
ing said control transfer device effectively en 70 means ineffective during the cooling of said ele
ergized independently of said time delay switch
ment, an electric heater for said element hav
ing element, and control lockout means respon—
ing an energizing circuit controlled jointly by
sive to a predetermined repeated energization of
said control device and said element to energize
said third heater during the initial part of suc
said heater only While said limiting means is
cessive cooling time delays for terminating fur 75 e?ective, said element having means for cleaner-
2,409,492 .
10
9
gizlng said heater upona predetermined heating
ofv said element, and means responsive to the
occurrence of a second predetermined condition
during said cooling period for energizing the
other of said windings to maintain said device
eluding a recti?er and an energization limiting
means, ‘a thermal time delay switching element
having an electric heater energized under the
control of said element for operating said ele
ment to render said limiting means ineffective
energized under the joint control of both said
only during the initial part of the cooling period
condition responsive means.
of said element, said element having means for
deenergizing said heater upon a predetermined
heating of said element, and a thermoelectric
7 9. In a control system, energizing circuit means
including an electroresponsive control device hav
ing complementary energizing windings, energize
ing control means for one of said windings in
cluding a unidirectional current supply means
having means for limiting the current supplied
thereby, a thermal timing element having a heat
er energized under the control of said element
for operating said element to deenergize said
heater upon a predetermined heating of said ele~
generator having a, combustion heater operated
under the control of said switching device during
said initial part of said cooling period for main
taining the other winding of said electromagnet
energized with unidirectional current to continue
operation of said combustion heater during the
subsequent part of said cooling period and after
said period.
13. In combination with energizing circuit
ment and temporarily render said current limit
means, a combustion heater having an alternat
ing means ineffective only during the initial part
of the cooling period of said timing element, and 20 ing current driving motor and igniter, a pair of
temperature responsive unidirectional energizing
electric heaters, a master switch having an elec
means normally rendered effective during said
temporary energization of said device for main
taining the other of said complementary windings
troresponsive relay controlled thereby and con
nected for alternately energizing said combustion
heater driving motor and one of said pair of elec
energized during and after the subsequent part 25 tric heaters, a snap action time delay switching
element heated by said one electric heater and
of said cooling period.
10. In a control system, energizing circuit
means including an electroresponsive device hav
ing complementary energizing windings, energiz
ing control means for one of said‘ windings in
cluding unidirectional current supply means hav
ing means for limiting the current supplied there
by, a thermal time delay switching element hav
ing an electric heater energized under the joint
control of said device and said element for oP- '
having a normally closed movable contact for
deenergizing said one electric heater after a heat
ing time delay and a pair of normally open mov
able contacts, one having a recti?er intercon
nected therewith for jointly energizing said'relay
and the other of said electric heaters with unidi
rectional current and the other for energizing
said igniter to start operation of said combustion >
heater during the initial part of the ensuing cool- ‘
ing time delay period of said switching element, a
thermoelectric generator heated upon establish
ment of combustion by said combustion heater
of the cooling period of said element, said elee
during said initial part of said period for main
ment having means for deenergizing said heater
upon a predetermined heating of said element, 40 taining said relay energized during the subse
quent part of said period and after said period
and thermoelectric generating means having a
_ and automatic lockout means cumulatively re
combustion heater started into operation under
sponsive to a predetermined repeated energiza
the control of said device during said temporary
tion of said other electric heater for preventing
energization of said one winding for maintaining
the other of said complementary windings ener 45 further energization of said heaters and said re
lay under control of said master switch in the
gized to continue operation of said combustion
continued absence of combustion by said com
heater during the subsequent part of said cooling
bustion heater.
'
period and after said cooling period.
14. A control system having, in combination,
ll. In a control system, energizing circuit
crating said element to render said current limit
ingjmeans ineffective only during the initial part
means including an electroresponsive control de
vice having'complementary energizing windings,
energizing means for one of said windings‘ in
cluding a recti?er having means for limiting the
50 an electroresponsive control device having ener
gization limiting means and cumulative energiz
ing means. for separately controlling operation
thereof, an electric heater having energizing cir
cuit means under the control of said device, cir
current recti?ed thereby, a thermal timing ele
ment having an electric heater provided with an 65 cuit means including a thermal timing control
element heated by said heater and having snap
energizing circuit under the control of said ele
action means for holding said element in one po
ment for periodically operating said element to
sition to produce snap action movement of said
render said current limiting means ineffective
element from said one position to deenergize said
temporarily during the initial part of each cool
ing period of said element, said element having 60 heater and to another position for rendering
said energization limiting means ineffective and
means for deenergizing said heater upon a pre
thereby effect atemporary operation of said de
determined heating of said element, and a ther
vice only during. the initial cooling of said ele
moelectric generator having a combustion heater
ment, condition producing means normally ren
operated under control of said device during each
deredeflective upon operation of said device, and
temporary energization thereof by said recti?er
condition responsive means for rendering said
for maintaining the other of said complementary
cumulative energizing means effective to operate
windings energized to continue operation of said
said device to maintain said condition producing
combustion heater when combustion is established
means effective during and after the subsequent
during the initial part of one of said cooling pe
70 cooling of said element.
15. A control system having in combination a
12. In a control system, energizing circuit
movable control member, means biasing said
means including a switching device having an op
member to move from one control position to
erating electromagnet provided with complemen
another control position, a pair of electromag
tary energizing windings, unidirectional energiz~
ing control means for one of said windings in 75 netic means for jointly holding said member in
riods.
v
-
'
11
2,409,492
said one position upon a predetermined energiza
tion of each of said means, circuit means includ
ing a condition responsive device for providing
said predetermined energization of one of said
electromagnetic means, circuit means including a
condition responsive device normally rendered ef
fective upon operation of said control member to
said one position for providing said predeter
mined energizaticn of the other of said electro
12
means for holding said element in said one posi
tion until after a predetermined heating of said
element, an electric heater having a circuit en
ergized under the joint control of said device
when ineffectively energized and said element in
said one position for biasing said control element
for snap action movement from said one position
to deenergize said heater and to said other posi
tion for temporarily effectively energizing said
magnetic means, and circuit means including a IS device during the initial part of the cooling time
snap action thermal timing device having an
in ,rval of said element predetermined by said
electric heater energized upon said predetermined
holding means, said element having circuit con
energization of said one electromagnetic means
trolling means for maintaining both said heater
under the joint control of said timing device and
deenergized and said device ineffectively ener
said control member in said other position for
gized during the subsequent part of said cooling
operating said timing device to deenergize said
heater and provide a temporarily increased en
ergization of said one electromagnetic means to
operate said control member from said one con
time interval of said element, condition produc
‘ng means for normally establishing a second con
dition under the control of said device upon ef
fective energization thereof, and circuit means
trol position to said other control position during 20 including a second condition responsive means
the cooling of said timing device.
ior maintaining said device effectively energized
16. A control system having in combination an
jointly with said ?rst condition responsive ener
electroresponsive control device having a con
gization control means upon the continuance of
trol member biased to move to a predetermined
said second condition during and after said sub
position upon only a partial energization of said 25 sequent part of said cooling time interval of said
device and having energizing circuit means in
element.
cluding control means for partially energizing
19. A sequential condition timing control sys
said device, circuit means including a thermal
em having, in combination, an electroresponsive
timing element for temporarily providing addi
control device having energizing circuit means
tional energization of said device to move said 30 including a ?rst condition responsive energiza
control member to another position while said
tic-n control means for inei‘r‘ectively energizing
element is cooling, a heater for
element hav
said device and energization control element for
ing energizing circuit means energized only when
temporarily eff ictively energizing said device dur~
saiddevice is partially energized and said element
ing the initial. cooling of said element and pro
a
Cl
is cool, said element having means for deener
g a subsequent cooling time delay there
gizing said heater after said element is heated to
,
a heater for said element having a circuit
a predetermined temperature, and means includ
energized under the joint control of said device
ing condition responsive means normally ren
and said timing control element only When said
dered effective during said temporary additional
device is inefiectively energized and said element
cnergization of said device for maintaining a sub 40 is cool whereby said heater is maintained deen
sequent additional energization of said device to
ergized during said subsequent cooling time de
maintain said member in said other position un
lay of said element independently of the con
der the joint control of said control means and
trol of said control device, condition producing
said condition responsive means.
means for normally establishing a second condi—
17. A control system having in combination 45 tion upon eiiective energization of said device,
alternating current circuit means including an
and circuit means including a second condition
electroresponsive switching device biased to a
responsive means for maintaining said device ef
predetermined position, circuit means including
a recti?er and a snap action thermal responsive
fectively energized jointly with said ?rst condi
tion responsive means during said subsequent
cooling time delay and thereafter to maintain
said condition producing means effective and said
heater deenergized independently of the control
of said timing element.
switching element movable upon a predetermined
heating thereof for temporarily providing a pre
determined direct current energization of said de
vice to effect operation thereof to another posi
tion only during the initial part of the interval
20. In combination, an electric control device
said element iscooling, a heater for said element
an electric heater having interconnected se
having energizing circuit means energized under
lective energizing circuit means including a ther
the control of said device in said predetermined
mal time delay double throw switch heated by
position and deenergized upon said predeter
electric heater under the joint control of said
mined heating of said element, and means in
device and switch and having a snap action
cluding thermoelectric generating means normal 60 means for holding said switch to extend the heat
13/ rendered effective upon said temporary pre
ing period thereof and thereby thermally bias
determined direct current energization of said
said switch to deenergize said heater and tem
device for providing a cumulative direct current
porarily effectively energize said control device
energizaticn of said device to maintain said de
during the initial part of the cooling time delay
vice in said other position during and after the
interval of said switch, condition producing
subsequent part of said interval.
~
means normally rendered effective under control
18. A- sequential condition timing control sys
of said device upon said effective energization
tem having, in combination, an electroresponsive
control device having energizing circuit means
including a ?rst condition responsive energize
tion control means for ineffectively energizing
said device and a thermal timing,r energization
control element biased when heated to move from
one control position to another control position
for effectively energizing said device. snap action
thereof, and condition responsive means having
connections for maintaining said device effective
ly energized upon continued effective operation
of said condition producing means during and
after the subsequent part of said cooling time
delay intervals.
BENJANIIN W. JONES.
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