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Патент USA US3064728

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Nov. 20, 1962
Filed Jan. 13, 1961
sa È
United States Éatent G 6 EC@
Patented Nov. 20, 1962
25 having a primary winding 27 and a secondary winding
Donald Lee Graves, Woburn, Mass., assigner to Elec
tronics Corporation of America, Cambridge, Mass., a
corporation of Massachusetts
Filed Jan. 13, 1961, Ser. No. 82,421
8 Claims. (Cl. 158-23)
This invention relates to an apparatus for the safe
automatic lighting of a fuel burner and for its safe shut
down in the event of either ignition or flame failure.
Fully automatic industrial furnaces burning oil or gas
employ either spark electrodes or a pilot burner to ignite
the main iburner. A pilot burner, if used, is ordinarily
ignited by spark electrodes. The heating period is initi
Terminal 21 is connected through the timer switches 31_,
33, and 35 to the timer motor 37 yback to ground. Termi
nal 21 is also connected through timer switch 39, the
starting interlock switch 41, the limit switches 43, and
timer switches 45, 47, and 49 through the main fuel Valve
51 to ground.
Starting interlock switch 41 must be
closed before the burner can be started. It is designed
to allow the fburner to start only when a given condition,
which must be met for starting purposes only, has lbeen
met. For instance, it may be a switch which opens when
the oil temperature falls îbelow a certain minimum level.
Or, in a burner having two independently controlled fuel
nozzles, with an igniting electrode near the r.first nozzle
only, it may Ábe a switch which is closed only when the
control. In order to put the burner into operation at
second nozzle is inoperative. The switch 41 may ‘be either
the beginning of each heating period, the ignition and
open or closed after operation has begun. The junction
fuel supply systems must be turned on in a proper se
53 of timer switches 45 and 47 is connected through the
quence. This is frequently accomplished by a program 20 llame relay switch `55 to a point 59 which itself is con
ming relay or an automatic timer which closes and opens
nected to the junction 60 of timer switches 47 and 49,
contacts in the control circuits at predetermined intervals.
to the ungrounded side 62 of the ignition circuit 61
The entire starting operation is known as the starting
through the time switch 63, and optionally to ground
cycle. On a typical burner, the iburner motor is first
through terminal 64 of an intermittent ignition or 0p
turned on. The ignition follows. If a pilot is used, the
tional burner motor connection 65. Junction 67 of the
pilot valve is opened at the same time. After a certain
limit switches 43 and of the timer switch 45 is con
interval, during which the ignition or pilot llame is estab
nected through thermal lock-out switch contacts 69 and
lished, the main fuel valve is opened. After another
71 to the ungrounded terminal 73 of transformer wind
interval, during which the main llame becomes estab
27, or through thermal lock-out switch contacts 69
lished, the ignition is turned olf, leaving the ‘burner in 30 ing
and 75 through the alarm 77 back to ground. The junc
normal running condition. When the space or vessel to
tion 79 of the starting interlock switch 41 and of the limit
be heated reaches the desired temperature, the contacts
switches 43 is connected through the control relay switch
of the thermostat open, shutting down the burner. When
81 to the control relay switch contact 83 and to the junc
the thermostat contacts close again, the starting cycle is
tion 85 of timer contacts 31 and 33. Junction S5 is~conrepeated. Because of the explosion hazard associated 35 nected to ground through the burner motor 87. The
with an industrial furnace of large capacity, a llame de
‘control relay switch comprising contact S3 is a single pole
tector is usually provided to shut down the burner in
double-throw switch which connects contact 83 either to
case of failure of the main llame or the pilot, in order to
contact 89 which is itself connected to terminal 21, or to
prevent the accumulation of unburned fuel in the com
contact 91 which is connected to the timer motor 37,.
bustion chamber.
40 The timer switch 35 is shunted by the flame relay switch
Flame detectors are of various types and respond to
- ated by the closing of contacts in a thermostat or similar
such flame characteristics as llame conduction or radia
The llame detection portion of the fuel fburner con
tion. In order to provide a high degree of safety, the
trol apparatus comprises flame sensing means such as
operating condition of the llame detector and control cir
photocell 95 or flame rod 97. Serially connected re
cuit is generally checked prior to the starting cycle to 45 sistors
99 and 101 are connected in shunt with the photo
»determine whether or not `burner operation can he safely
cell 95. The anode 103 of photocell 95 is connected to
initiated. This is usually accomplished by applying to
the tap 105 on transformer winding 17 through a capaci
the control circuit a simulated flame signal which serves
tor 107. The junction 109 of resistors 99 and 101 is con
to operate the circuit in a normal manner. If the control
nected to the control grid 111 of triode 113. The cathode
circuit does not function properly on the simulated llame 50
115 of triode 113 is connected to ground, and its anode
signal, then the control apparatus is safely held in
117 is connected lto the terminal 119 of secondary wind
ing 15, the other terminal 121 of which is connected to
It is the principal object of this invention to obtain a
the control grid 123 of triode 125. The control grid 111
fuel burner control apparatus which offers a high degree
connected to ground through serially connected capaci
of safety and Versatility with a minimum number of 55 is
tor 127 and resistor 129. The control grid V123 is con
nected to ground through resistor 135 which is shunted
Other and incidental objects of this invention will be
‘by serially connected capacitor 131 and resistor 133.
apparent to those skilled in the art from a reading of
The cathode 137 of triode 125 is connected to ground, and
this specification and an inspection of the accompanying
the anode 139 of triode 125 is connected to the un
drawing in which:
switching members.
grounded terminal 141 of transformer winding 17 through
FIGURE 1 shows a circuit diagram of a fuel burner
the llame relay 143. The llame relay 143 is shunted by
control apparatus in accordance with this invention, and
a capacitor 145. The heaters 147 and 149 of triodes 113
FIGURE 2 is a time chart showing the sequence and
and 125 are supplied from the secondary winding 19 of
relative duration of the closing of the contacts of the timer
transformer 11.
used in the circuit of FIGURE 1.
65 l 'The junction 151 of capacitor 127 and resistor 129 is
Referring now to 'FIGURE l, there is shown a trans
connected through timer switch 153 and through the
former 11 having a primary Winding 13, and secondary
operating control switch 155 to the terminal 159 of trans
windings 15, 17 and 19. One terminal 21 of the primary
former winding 29. The junction 1‘61 of capacitor 131
winding 13 is connected to the ungrounded side of an
and resistor 133 is connected through contact 163 of the
A.C. power line, while the other terminal 23 of the 70 single-pole double-throw llame relay switch 165 and
primary winding 15 is connected to the grounded side of
through timer contact 167 to one terminal 169 of the con
the power line. There is also shown another transformer
trol relay 171. The other terminal 173 of control relay
171 is connected to the terminal 175 of transformer wind
ing 29. Terminal 173 is connected to ground through a
resistor 177. The junctionlSS of timer switches 153
and 1181 and of operating control switch 155 is con
nected to contact 185 of the flame relay switch 165. The
terminal 169 is connected to junction 183 through the
heater of thermal relay 179 and through timer switch 181.
' Operation
-The operation of the system shown in FIGURE'I
of tube 113 is negative, a current flows from tap 159 Vof
transformer 25 through capacitor 127 and the grid-cath
ode path yof tube 113 to ground back through resistor 177
to tapV 175 of secondary winding 29. In the alternate
half-cycle when the voltage at tap 159 is negative, and the
voltage at tap 119 is positive, tube 113 is held cutoff as a
result of the net voltage appearing across capacitor 127.
The charge that leaks off capacitor 127 during this alter
nate half-cycle through resistors 101 and 129 is negligi
ble. When tube 113 is held cutoff, tube 125 is permitted
will be described for an oil burner with an interrupted
gas pilot. llt will lbe assumed that a source of power,
to conduct, thereby energizing relay 143.
usually 120 volts, single phase A.-C. is present at input
ly energized by the power supplied by secondary winding
29 through t’ne resulting path comprising timer contact
terminals 21 and 23. It will also be assumed, initially,
thatthe system previously underwent a complete starting
cycle, that operating control switch 1'5'5 is open,'and that
timer 37 is in the starting position, as shown in FIGURE 2.
Normal Starting Cycle
Transformer 11 is energized by the power supplied to
input terminals 21 and 23, thereby providing power for
When relay 143 is energized, relay 171 is simultaneous
167 and contact 185 of relay switch 165 and operating .
control switch 155. When relay 171 is energized, burner
motor 87 is energized through contact 89 of relay switch
83. Timer motor 37 is also energized through contact
89 of relay switch 83 and timer switches 33 and 35.Y The
20 starting interlock switch 41 and timer contactV 39 are also
shunted simultaneously by switches S1 and 83 of relay
filaments 147 and 149 which are connected to winding
1‘9. ' Transformer 25 is simultaneously energized through
' As the timer cycle progresses, timer contact 39 opens
'timer contact 39, starting interlock switch 41, limit
and timer contact 31 closes simultaneously after threeY
switches 43, and the thermal lock-out switch 69, the op 25 seconds of timer rotation. The circuit is not affected at
eration of which will be described hereinafter. The
this time. After ñve seconds of timer rotation, timer
’131.-C. voltage appearing at tap 105 of winding 17 is cou
contact 153 opens, removing the checking signal from
pled to the yllame detecting circuit through the capacitor
the detection circuit which was applied thereto during the
107. The flame detecting circuit comprises either -the
ñrst ñve seconds of timer rotation. At the same time,
flame rod 97 or the photocell 95 which is used to detect 30 timer contact 181 closes providing a current path through '
Visually the main llame. The unidirectional current
the parallel combination of heater 179 of the thermal ~
>which ñows through capacitor 107 as a result of the recti
lock-out switch 69 and closed contacts 185 and 167. The
fying elements in the ñame detecting circuit serves to pro
-charge on vcapacitor 127 leaks off through resistors 101
uduce a net negative charge on the plate of capacitor 107
and 129 subsequent to the opening of contact 153. This
`connected to llame rod 97. The voltage appearing-across 35 discharge time constant is chosen so that after about one
’the capacitor 107, then, is referred to the grid and cath
second, a ysufficient amount of charge -has leaked olf ca
ods of tube 113 through isolating resistor 99 and through
pacitor 127 to permit tube 113 to conduct, thereby cutting
'off tube 125 and de-energizing relay 143. However,
The grid 111 of tube 113 is biased negatively with re
before relay 143 is deenergized and, infact, after >six
spect to the cathode 115 and this bias voltage, developed 40 seconds of timer rotation, timer contact 167 opens, there
nthe portion of secondary winding 17.
'when a'ñanie is detected or when a checking signal is
by removing the 'shunt current path around heater .179.
applied, is ~sufficient to Vdrive tube 113 to cutoff. When
Heater 179 thus conducts current andïbegins to heat up. '
'tube`11`3 is biased to cutoff and is non-conducting, no bias
After nine seconds of time rotation, timer contact v35
voltage is 'developed across resistor 135 and tube 125 is
opens but does not interrupt power applied to timer motor
thus able to conduct. Capacitor 145, which »is connected 45 37 since contact 35 is shorted by relay switch 93. Y Con
in shunt with relay 143, stores sufficient energy during
tact 35 recloses after twelve -seconds of timer rotation
the half cycles when tube 125 is conducting to keep relay
and thus precludes subsequent interruption of power to
143 energized during the half cycle when tube 125 is not
timer motor 37 by the opening of switch 93. ?At the,vv
conducting. vIn this manner, a bias voltage developed
same time, timer contact 63 closes'but does not affect the
across capacitor -107 by the ñame detector drives tube 113 50 circuit. Timer contact 45 closes after 15 seconds/¿lof
to cutoff .and Vthus allows tube 125 to conduct and ener
time rotation and’thu's energizes the ignition circuit;t 61
lg'ize relay'1'43.
When -tube 113 is not biased to cutoiî, a current flows
during positive half cycles from tap `119 of transformer
11 through tube »113 back to tap 121k of transformer V11
through lthe -parallel paths of resistor 135 and serially
Yconnected-resistor 133 and capacitor 131. The direction
t of >currentflow is such as to produce a voltage drop across
'through ‘contacts 47 Vand ‘63, which ignition circuit in
cludes the ignition transformer and the pilot fuel vs'i'alve.
>With the burner motor `87 _and the ignition circuit 61Y in
55 the energized state, a pilot ñame is established.
The pilot llame that -is initiated causes a unidirectional
ícurrent to ñow through capacitor 107 from tap 105 of
'secondary winding 17.V As previously described, tube 113
resistor 135, Vwhich is negative at the ‘grid of tube 125
is cut olf and tube >125 conducts, thereby energizing relay
_and positive’atthe cathode. This bias voltage appears at 60 V143. After 25 seconds of timer rotation, contact167
Y the same time that the plate of tube 125 is positive and'is
thus suñicient to drive tube 125 to cutoff. `Conventional
polarity transformer markings are shown on the windings
of transformers llvand 25. It is therefore vevident that
recloses, completing through contact Y185 of relay-switch
>165 a shunt path around the lock-out switch heater 17,9
which thus stops heating. At the »same time, -contact 47
:opens and contact 49 closes. Since >relay 143 is ener
relay k143 is Vde-energized whenever tube 113 is in the 65 îgized, the main fuel valve 51 is then energized vfrom the
conducting state.
Upon need for burner operation, operating control
switch «155 is closed either Ymanually or by means of a
power lines through timer contacts 45 and 49 and switch
55. The'ignition circuit 61, however, `remains energized
whenrcontact 47 opens because of the shunt pathpro
vided by relay switch 55. The main-ilameis thus estab
-thermostatic control. For checking purposes, a flame
signalis ."simulated.' This occurs whenever operating 70 Vlished and is detected by the Vñame detecting element -95
control l'switch 155 and timer contact 153 are closed. The
secondary windings of Ytransformers 11 and 25 are -so
If the conduction of tube 125 reduces to theY point
rrelated in phase that tap 159 of transformer 25 is positive
where relay 143 is de-energized after 25 seconds of timer
-when tap 119 of transformer 1/1 is negative; Whenthe
rotation, i.e., when flame-is required to be detected, »then
voltage. 31125311.59 is positive-_and the'voltageon plate 117 75 tube'125 Vwill beheld in the non-conductive state. InV
describing the safety feature of the present invention that
is apparent at this time, it should be pointed out that
operating control 155, timer contacts 167 and 181 are
closed, that timer contact 153 is open, and that contact
185 is connected to switch 165. If flame signal ceases or
diminishes sufficiently to let tube 113 conduct, and the
conduction of tube 125 reduces to the point where relay
143 will not be energized, switch 165 will break from
contact 185 and connect to contact 163. On the half
Operation fOr Oil Burner With Interrupted Spark Ignition
The ignition circuit 61 and main fuel valve 51 are con
nected as shown and a jumper connecting terminal 50 and
terminal 64 is provided. The operation of the circuit is
the same as described for the normal starting cycle until
after 15 seconds of timer rotation. Contact 45 closes,
completing a circuit from terminal 67 to i-gnition circuit
61 through contact 47 and contact 63 and completing a
from terminal 67 to the main fuel valve 51 through
cycles where the voltage applied to plate 139 and the volt 10
contact 47 and the jumper between terminals 5t) and 64.
age at tap 175 are negative, a current tlows through the
With burner motor 87, ignition circuit 61, and main fuel
heater 179 and through timer contact 167 to the junc
valve 51, now all energized, a flame is established. When
tion 161 of resistor 133 and capacitor 131. Current ñow
the main flame is sensed, the signal thus developed causes
during this half-cycle is such as to produce a voltage across
tube 125 to conduct, thereby energizing relay 143. Con
capacitor 131 that is of proper polarity to bias tube 125
tact 167 closes after 25 seconds of timer rotation, thus
negatively. Thus, when the plate voltage of tube 125 be
providing a shunt current path around heater 179’ through
comes positive in successive half-cycle, the tube will have
contact 135 of switch 165, which heater thus stops heating.
suiiicient negative bias voltage between grid 123 and
the same time, contact 47 opens and contact 49 closes
cathode 137 to maintain tube 125 cut-olf. By this process,
but this does not affect the circuit operation at this time
relay 143 is prevented from being energized if it assumes
because of the shunt path provided by relay switch 55.
a de-energized position during any part of the burner
35 seconds, contact 63 opens, thus de-energizing
starting cycle after contact 167 closes at 25 seconds of
ignition circuit 61. The operation of the circuit is sub
timer rotation.
stantially the same as the operation described for the
The pilot flame is extinguished after 35 seconds of timer
starting cycle after contact 33 opens at 45 seconds
rotation as a result of timer contact 63 opening. How
ever, relay 143 is maintained in the energized state as a
of timer rotation.
Operation Following POwer Interruption During Normal
result of the continued detection of the main flame. After
Starting Cycle
45 seconds of timer operation timer contact 33 opens and
de-energizes timer motor 37. There is no further switch
If power is interrupted prior to the opening of contact
ing action until the operation control switch 155 opens as 30 39 at a time three seconds after the start, normal sequence
a result of information provided by the temperature of
of operation proceeds when the power is resumed. How
the headed space or vessel.
ever, if power is interrupted after three seconds of timer
rotation when contact 39 opens and contact 31 closes,
Normal Shutdown
When the heat demand is satisñed the operating control 35 relay 171 cannot be re-energized when power is resumed
because of contact 39 and switch 81 both being open.
switch 155 is opened either manually or by the thermo
burner motor 87 will be re-energized through contact
static control. This de-energizes relay 171. The circuit
31 and timer motor 37 will also be re-energized through
through contact 89 and switch 81 is broken and connection
contact 31 and contact 91 of switch 83 when power is
to contact 91 is thus made. The burner motor S7 remains
energized through contact 31. The main fuel valve 51 and 40 resumed. Both motors will remain energized until con
tact 31 opens at time 60 seconds and no other loads will
the optional burner motor connection 65 are de-energized
by the opening of relay switch 81, and the timer motor 37
is re-energized through timer contact 31 and contact 91
of relay switch 83. No effect is produced upon the cir~
be energized during this period because of the afore
mentioned open state of both contact 39 and switch 81.
Operation for False Flame Signal During Checking Period
cuit when timer contacts 45 and 49 open and contact 47 45
The operation of the circuit progresses as a normal start
closes after ñfty seconds of timer rotation. Also, no effect
ing cycle up through the opening of contact 153 at time
is produced on the circuit when contacts 153 and 33 close
and contact 181 opens after 55 seconds of timer rotation.
live seconds after starting. Although the checking signal
is then removed, relay 143 remains energized because of
‘After sixty seconds of timer rotation, contact 31 opens and
real or simulated signal at that time. Contact 167 opens
de~energizes the burner motor and timer motor. At the 50 at time six seconds and current flows through heater 179
same time, contact 39 closes but has no eiîect at this time.
which subsequently begins to warm up. Contact 35 opens
rThe timer now has made one complete revolution and
at time nine seconds and the timer motor is thus de-ener
is again in the starting position. When the starting inter
gized because switch 93 is also open. After about one
lockiswitch 41, limit switches 43, and operating control
minute, the heated bimetallic element of the lockout switch
switch 155 are again actuated simultaneously, a repeat of 55 69 detiects from contact 71, thereby de-energizing trans
the cycle just described will result.
former 25 which thus de-energizes relay 171. Blower
Several other modes of operation are possible using the
motor 87 remains energized through contact 31 and timer
circuit of the present invention for various combinations
motor 37 is re-energized through contact 31 and contact
of main flame fuel and igniting means. By way of ex
60 91. Both motors now remain energized until contact 31
ample, and to demonstrate the versatility of the present
opens at time 60 seconds. No other loads will be ener
invention, operation of the circuit for a few of the possible
gized during this period because both contact 39 and
fuel and ignition means combinations will be described
switch 81 are open. When contact 39 closes at time 60
seconds, power is again applied through contact 39, start
Operation for Gas Burner With Intermittent Gas Pilot 65 ing interlock switch 41 and limit switches 43 to junction 67.
However, since lockout switch 69 is not connected to
The ignition circuit 61 is connected as shown. A pilot
contact 71, transformer 25 cannot be energized. There
valve control is connected in the position of block 65.
can be no further burner operation until lockout switch 69
The sequence of operation is the same as in the normal
is manually reactuated to its normal position.
operating sequence with the exception that pilot valve 70
Operation for Flame Failure or Loss of Detection
control 65 is not de-energized after 35 seconds of timer
After Contact 47 Opens
rotation, but rather remains energized for as long as
the main fuel valve 51 is energized. A failure of the
The operation of the circuit is the same as the operation
main ñame will not de-energize the fuel valve 51 if the
for the normal starting cycle until the main flame is
pilot ñame remains burning and detected.
75 established and is detected by the photocell. However, if
including the first switch of said flame relay -in the ener
gizedlstate and a second timer switch to energize said con
trol relay, means including the iirst switch of said control
relay in its energized state and a third timer switch to
energize said timer motor, means responsive to the opera-V
tion of said timer motor to open said second timer switch,
means including the second switch of said control relay
insufii'cient llame signal is developed as a result of loss of
ñame or other factors, relay 143 becomes dez-energized.
There can be no Afurther power applied to ignition circuit
61 and main fuel valve 51 because both >contact 47 and
switch 55 are open. Heater 179 begins to heat up because
contact 185 no longer provides a shunt current path.
Lockout will occur about one minute after contact 185 is
opened, thereby causing relay 171 to become cle-energized.
Timer motor 37 will then become re-energized through
for maintaining said control relay in its energized state,
switch 69 is manually reactuated to its normal position.
Therefore, the circuit of thepresent invention provides
state for maintaining said timer motor in its energized
state, and means including a fourth timer switch responsive
many safety features which are readily apparent to those
skilled in the art. Some of the safety features provided
to the further operation of said timer motor to actuate said
ignition means.
means responsive to `the operation of said timer motor to
contact 31 and switch contact 91, and Will advance through 10 remove said checking signal and deenergize said ñame
relay, means responsive to the further operation of said
the cycle until both timer motor 37 and blower motor 87
timer motor to open said third timer switch, means includ
are de-energized by the opening of contact 31 at time 60
ing the second switch of -said flame relay in its deenergized
seconds. When lockout occurs, alarm 77 is energized until
2. A programming apparatus according to claim l in
cluding means responsive to the further operation of said
tion which is not affected by normal variations of line 20 timer motor to deenergize said timer motor.
3. A programming apparatus according to claim 2
voltageor ambient temperature. ,
yfurther comprising means including a ñfth timer switch
(2) A check, prior to ignition period, of the ability of
and the lirst switch of said control relay in its deenergized
the iiame responsive relay to pull in with signal and` to
state to energize again said timer motor and reset it toits
drop out when there is no signal. This check is eiîective
starting position.
whether or not the ampliiier is operating at the time burner
4. A programming apparatus according to claim 3
operation is called for and cannot be adventitiously
further comprising means including the second ‘switch of
-said control relay in its deenergized state to .prevent ener
(3) A lockout in the event a'false signal is prolonged
gization of said ignition means and main fuel valve while
for a minute or more during safety check to avoid danger
of initiating another firing cycle,
30 said timer is resetting.
5. A programming apparatus according to claim 3 Vand
(4) An optional pre-purge period to clear the furnace
further comprising a thermally actuated lockout device
of unburned gases,
comprising a heating element serially connected with said
(5) A post-purge period to sustain combustion air while
control relay and a lockout switch actuated thereby, a
a slow-operating gas Valve is closing,
(6) Non-recycling of the operation following ignition, 35 sixth timer switch andthe first switch of said'ñame relay
(1) A precise ignition trial period of a short, safe dura
in its energized state being'serially connected to provide
ñame, o_r component failure, and
(7) A cut-off of the flame-responsive relay current
an electrical path shunting said heating element.
6. A programming apparatus according to claim 5
wherein said heating element is energized upon 'the open
gizing the main fuel valve without ignition Abeingpresent
40 ing of said shunt path, and wherein the energization of
during lock-out procedure.
said heating element beyond aV predetermined time 'inter-val
. It should be noted also »that-several circuit simplifica
causes the lockout switch actuated thereby to deenergize
tions are provided by the system design of the presentin
-said control relay.
vention. For example, the location of starting interlock
7. A programming apparatus according -to claim V`6
circuits permits starting andre-'setting switches 39 and 31
following a tiame failure to avoidvpossibility of re-ener
to be combined as a single-pole double-throw switch. The 45 further comprising a seventh timer switch connected in
series with'said heating element.
8. A programming apparatus for a fuel -burner-having _,f
electrically actuated ignition means and a mainfuel'valvej
circuit arrangement also permits a two-pole control relay
171 with one single-throw and one double-throw contact
’to initiate burner motor operation, to initiate timer 'motor
operation, to provide a maintaining circuit around the
starting interlock circuit, and to interrupt power applied
Vsaid programming apparatus comprising: an -operatin-'g
to ignition and fuel valve Vloads and to its own actuator
burner operation, a timer having a motor and a plurality 4 ¿
vwhen such action is required. This permits economical
»relay design and circuit design since oneïside of the control
of switches controlled thereby, ñame sensing means, a
ñame relay connectedto the output of said flame sensing
control switch to be actuated upon the need for fu'elj
relay contacts are electrically common toeach other, -
thereby permitting simpliñed wiring.
We claim:
means and having an energized state indicative 4'of the
55 presence of flame and a deenergized state indica 've of the
absence of flame, said flame relay having'an actuator and
1. A programming apparatus for a fuel burner having
electrically actuated ignition means and a main fuel valve,
said programming apparatus comprising: Van operating
iirst and second switchescontrolled therebyf'a control
, relay having an energized state indicative of the need for
fuel burner 'operation and a deenergized state indicative
` control switch to be actuated'upon the need for `fuel burner 60
of no need Vfor fuel burner operation, said control relay
operation, a timer having a motor and a plurality of
switches controlled thereby, flame sensing means, a ñarne
relay connected tothe output of said-flame sensing means
having an actuator and lirst and second switchesfcontrolled
thereby, means including said operating control switch and
and having an energized state indicative of the presence . . a first timer switch to generate a checking signal to simu
of flame and a deenergized state indicative of the absence 65 late the presence of ilame and thereby cause-the energiza- v
tion of said ñame relay, means including the first switch
of llame, said flame relay having an actuator and first and
-second switches controlled thereby, a control relay having
an energized state indicative of the need for fuel burner
operation arid a deenergized state indicative of no need
forf-fuel `4burner operation, said ’control relay having an
actuator and iìrstïand second'switches- controlled thereby,
means including'a switch responsive to the- need for fuel
.burnereoperation’and a first timer switch to generate a
checkingsignal to .simulate the presence of 'flame and »
sof said lñame relay VAin the >energized vstate and a'second
timer switch to energizesaid control relay, means includ-y
.ing the ñrst switch of said control relay in its energized
state and a Vthird timer switch to ,energize said timer
motor, means responsive tothe operation of'said 'timer
motor to open said second timer switch, means including
the second switch of said control relay `for maintaining
said control relay in its energized state, meansY responsive
thereby causeV the energization of said flame relay, means 75 to the operation of ysaid timer motor to remove said check
ing signal and deenergize said flame relay, means responsive to the further operation of said timer motor to open
said third timer switch, means including the second switch
of said flame relay in its deenergized state for maintaining
said timer motor in its energized state, and means inelud- 5
ing a fourth timer switch responsive to the further opera-tion of said timer motor to actuate said ignition means.
References Cited in the ñle of this patent
2 616 490
Wilson et al ____________ __ Nov. 4, 1952
Marshall et a1
June 5 1956
Graves et a1 """"""" " Jan 3’ 1961
' """""""" "'
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