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Патент USA US2117021

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May 10, 1938.
Filed April 28, 1934
33 21
Patented May 10, 1938
Lester D. Cotea, Dayton, Minn, assignor to Min
neapolis-Honeywell Regulator Company, Min
neapolis, Minn., a corporation of Delaware
Application April 28, 1934, Serial No. 722.907
1 Claim. (Cl. 7158-—28)
description and theaccompanying single drawing
The present invention relates to improvements
in fuel burning systems and is particularly con
cerned with the provision 'of a fuel burning sys
tem in which the supply of fuel is increased after
combustion has been properly established.
The object of the present invention is the
provision of a fuel burning system including valve
. mechanism adapted to supply either a large or a
small amount of fuel to a burner, and to entirely
10 interrupt the supply of fuel thereto, together with
means for initially operating the valve mecha
nism in such manner as to cause the same to
supply a small amount of fuel to the burner
which, if successfully ignited, is thereafter in
15 creased to a larger supply.
In this manner, a
trial ignition period can be instituted without
delivering a large amount of fuel to the burner
and if this ignition period is successful in es
tablishing combustion, then the full desired sup
ply of fuel is‘ established thereby making it pos
sible to check the operation of the system with
out delivering a very large supply of fuel‘ to the
burner in the event ignition is not successful.
The inventionfurther includes the usual safety
25 mechanism by which the system is rendered in
which is a diagrammatic showing of one form of
the present invention.
Referring to the drawing, the valve mechanism
comprises a low capacity valve III which is cp- 5
erated by an eletromagnetic winding ll and a
high capacity valve I 2 which is operated by an
electromagnetic winding l3, the arrangement be
ing such that valves l0 and I2 are moved to open
position upon energization of their respective 10
electromagnetic windings l2 and I3. The fuel
supplied by the low capacity valve i2 is ignited
by an electrically operated ignition means l4.
Preferably, the system includes a burner motor
I 5 which serves to supply the combustion sup 15
porting vair and atomizes or mixes the fuel and
air in any of the manners now well-known in
the art.
The system is controlled by a main control in
dicated generally at I6 which is herein shown as 20
comprising a room thermostat which includes a
bimetallic coiled element I‘! having one of its
ends ?xed as indicated at l8. The other end of
bimetallic element l1 controls a contact blade l9
and a contact blade 20. When the room tem- 25
operative in case combustion is not successfully
falls, contact blade I9 ?rst engages a
established and the arrangement is such that the perature
contact 2| and upon further fall in the room tem
large supply of fuel cannot be furnished to the perature
contact blade
burner before the safety mechanism has checked vSimilarly, upon a room 20 engages a contact 22.
temperature rise, the con
30 the operation of the apparatus.
In the speci?c embodiment of the invention tact blade 20 ?rst disengages its contact 22 and 30
thereafter the contact blade l9 disengages ‘its
herein disclosed, the *valve mechanism’ comprises contact
a pair of valves one of which is preferably a low
The system further includes a thermal safety
capacity valve and the other of which is pref
35 erably a high capacity valve. The low capacity switch which comprises a switch 25 that is ther
valve is initially energized under the command mally operated and an electric heating element 26
of a main control device and, in the event the for operating the same. Such thermally operable
supply of fuel furnished by this low capacity valve switches are well-known in the art and the
is successfully ignited, then the high capacity thermal safety switch utilized in the present in
40 valve is energized and the low capacity valve is vention may well take the form shown in Fred
deenergized. The ignition means for igniting the erick S. Denison application Ser. No. 226,395 40
which was ?led October 15th, 1927.
fuel supply to the burner is controlled simul
The system of the present invention further
taneously with the low capacity valve in the pre
includes a combustion responsive switching mech
ferred form of the invention. Also, it is pref
45 erable to provide a burner motor which is ener anism which preferably takes the form of a, slip
friction stack switch generally indicated at 28.
gized the whole time that the system is in op
The stack switch 28 includes ?rst cold and hot
The system also is preferably arranged to give
a recycle upon a failure of ?ame or momentary
power failure.
slip friction mechanism, the arrangement being
Other objects of the invention will be found
such that switch arm 3| engages contact 29 in
in the'drawing, the following description and in
the appended claim.
switches comprising contacts 29 and 30 and a
switch arm 3| that is operated through suitable
For a better understanding of the invention,
reference may be had to the following detailed
the absence of combustion and engages contact
30 upon the establishment of combustion. The
arrangement is such that switch arm 3| engages
contact 30 prior to disengaging contact 29 upon
establishment of combustion but does not en
cold electrodes 33 and the bridging mercury 21
of mercury switch 32 and wire 1| at which point
disengaging contact 36 upon cessation of com
the circuit branches, one part going by way of
bustion. The stack switch 26 further includes‘ wire 12, ignition means l4 and wire 13 to line
second cold and hot switches comprised by a mer
46, whereas the other portion goes -by way of
cury switch 32 having a pair of cold electrodes wire 14, electromagnetic winding H of low ca
33 and a pair of hot electrodes 34 adapted to be pacity valve l6, wire 15, and wire 16 to line 46.
bridged by a body of mercury 21. Stack switch
In this manner, upon a call for heat by the
mechanisms of this general character are well
thermostat IS, the burner motor I5 is en
known in the art and the one diagrammatically room
ergized and a small supply of fuel is furnished 10
illustrated herein may well take the general form
10 shown in Figs. 2 and 3 of Frederick S. Denison to the burner which should be ignited by the
ignition means l4. In the event ignition is not
gage contact 29 until a delayed interval after
application Ser. No. 697,687, ?led November 11th,
The room thermostat l1 and the stack switch
28 cooperate in the control of a relay 35 which
comprises a relay coil 36 that attracts an arma
ture 31 when energized.
An armature 31 con
trols switch arms 38, 39 and 46 to move the same
into engagement with respective contacts 4|, 42
20 and 43 upon energization of relay coil 36.
High voltage electrical power is furnished to
the system by line wires 45 and 46. Low voltage
electrical power is furnished by a step-down
transformer 41 having a low voltage secondary
25 48 and a high‘voltage primary 49 which is con
nected to line wires 45 and 46 by wires 56 and 5|.
successfully established within a predetermined
timed period, the heating element 26 will cause
opening of safety switch 25 whereupon the system 15
will be rendered inoperative until manual inter
vention. On the other hand, if combustion is
successfully established within this period, switch
arm 3| will move into engagement with contact 20
36 and thereafter will disengage contact 29.
Likewise, mercury switch 32 will tilt to its oppo
site position wherein the hot electrodes 34 are
bridged by the mercury 21 thereof.
Engagement of switch arm 3| with contact 36
immediately establishes a maintaining circuit for 25
relay coil 36 which maintaining circuit opera
The remaining circuit connections will be de
scribed under the heading “Operation”.
With the parts in the position shown, the
room temperature is above the desired value and
the relay coil 36 is deenergized. The cold switches
comprising switch arm 3| and contact 29 and
35 the electrodes 33 of mercury switch 32 are both
closed and the combustion responsive hot switches
' comprised by arm 3| and contact 36 and the
electrodes 34 of mercury switch 32 are both
opened indicating that there has been a decrease
40 in the temperature of combustion. Low and high
capacity valves l6 and |2 are both closed and
the ignition means |4 and‘burner motor l5 are
both deenergized.
When the room temperature drops so as to
bring contact blades l9 and 26 sequentially into
engagement with their contacts 2| and 22, an
energizing circuit for the relay coil 36 and heat
ing element 26 is established as follows: second
ary 48, wire 55, safety switch 25, wire 56, contact
50 2|, contact blades l9 and 26, contact 22, wire
51, wire 58, switch arm 3|, cold contact 29, wire
59, heating element 26, wire 66, wire 6|, relay
coil 36 and wire 62_to the other side of second
ary 48.
Energization of relay coil 36 , moves
55 switch arms 38, 39 and 46 into engagement with
their respective contacts 4|, 42 and 43. Engage
ment of switch arm 39 with its contact 42 es
tablishes a holding circuit for relay coil 36 and
heating element 26 as follows: secondary 48,
wire 55, safety switch 25, wire56, contact 2|,
contact blade |9, bimetallic element l1, wire 63,
contact 42, switch arm‘ 39, wire 64, wire 58,
switch arm 3|, contact 29, wire 59, heating ele
ment 26, wire 66, wire 6|, relay coil 36 and wire
~65 62 to the other side or secondary 48.
Engagement of‘ switch arm 46 with contact
43 establishes, energizing circuits for burner
motor |5, ignition means l4 and low capacity
valve I6. The energizing circuit for burner
motor I5 is as follows: line 45, wire 65, contact
43, switch arm 46, wire 66, wire 61, burner motor
l5, and wire 68 toline 46. The energizing cir
cuits for ignition means l4 and low capacity
valve W are as follows: line 45, wire 65, contact
43, switch arm 46, wire 66, wire 69, wire 16,
tively deenergizes heating element 26 by estab
lishing a shunt therearound. This maintaining
circuit is as follows: secondary 48, wire 55, safety
switch 25, wire 56, contact 2|, contact blade
l9, bimetallic element |1, wire 63, contact 42,
switch arm 39, wire 64, wire 56, switch arm 3|,
contact 36, wire 19, switch arm 38, contact 4|,
wire 86, wire 6|, relay coil 36 and wire 62 to 35
the other side of secondary 46. Then as soon as
switch arm 3| disengages contact 29, the original
energizing and holding circuits for relay coil 36
and heating element 26 are interrupted. Move
ment of mercury switch 32 to its hot position 40
opens the circuit between cold electrodes 33 to
interrupt the energizing circuits for ignition
means l4 and low capacity ‘valve l6. Closure
of the circuit through hot electrodes 34 of mer
cury switch 32 however establishes an energiz
ing circuit for high capacity valve |2 which is
as follows: line 45, wire 65, contact 43, switch
arm 46, wire 66, wire 69, wire 86, hot electrodes
34 and the mercury 21 of mercury switch 32,
wire 83, electromagnetic winding l3 of high ca 60
pacity valve 12, wire 64, and wire 16 to line 46.
The system is now in normal operation, com
bustion having been established and resulting in
an increase in the supply of fuel.
When the room temperature begins to rise so 55
as to move contact blade 26 from engagement
with contact 22, relay coil 36 will be maintained
energized either by the previously described hold
ing circuit or by the maintaining circuit. How
ever, when the room temperature rises sufliciently
to additionally move contact blade l9 from en
gagement with contact 2|, then the maintaining
circuit will be interrupted, as will be the hold
ing'circuit if switch arm 3| has not as yet dis
engaged contact 29, and the relay coil 36 will be
deenergized. This relay. coil cannot thereafter
be again energized until such time as the room
temperature falls sufficiently to bring both con
tact blades I9 and 26 into engagement with their
respective contacts 2| and 22 and until switch 70
arm 3| disengages contact 36 and'engages con
tact 29.
In the event there should be a failure in the .
supply of electrical power while the system is in
operation, relay coil 36 will be deenergized and
cannot be again energized upon resumption of
power unless the stack temperature has de
creased sufficiently to move switch arm 3| from'
engagement with contact 30 and into engage
ment with contact 29. Also, at this time, both
blades I9 and 20 of the room thermostat l6 must
be in engagement with their contacts 2| and 22
in order to reenergize relay coil 36. In the event
there should be a failure of ?ame during normal
operation, switch arm 3| will ?rst disengage con
tact 30 whereupon relay coil 36 will be deener
gized after which, upon engagement of switch
all of the other usual features such as a recycle
upon power failure or ?ame failure, together with
control of the ignition means.
by those skilled in the art and I therefore intend
to be limited .only by the scope of the appended
I claim:
From the foregoing description, it will be ob-v
served that the present invention provides a trial
ignition period in which a relatively small amount
of fuel is supplied. If ignition is not established,
25 the system is shut down without very ‘much fuel
having been delivered to the. burner or combus
tion chamber. In the event'combustion is suc
cessfully established, the supply of fuel is in
creased to the desired amount. In this manner,
30 if the system is not operating properly a much
smaller amount of fuel is supplied to the burner
before the system is rendered inoperative by the
safety mechanism.
In combination, a room thermostat, a thermal
‘safety switch including an electric heating ele
arm 3| with contact 29 and if the room thermo
It will be apparent that many changes in the
speci?c arrangement shown herein can be made 6
ment, a relay coil, a control switch and a load
stat switches are both closed, relay coil 36 and
15 heating element 26 will again be energized to es
tablish anew trial ignition period. If combus
tion is not successfully reestablished at this time
the system will be rendered inoperative by the
safety switch and remain so until manual inter
It will also be noted that the invention provides
switch closed thereby when energized, ?rst cold
and hot combustion responsiveswitches overlap 15
pingly controlled upon a rise in the temperature
of combustion, an energizing circuit for said re
lay coil and heating element in series including
said room thermostat, safety switch and ?rst cold
combustion responsive switch, a holding circuit 20
for said relay coil including said room thermo
stat, ?rst hot combustion responsive switch, and
said‘ control switch, a. burner motor, ignition
means, ‘a low capacity fuel valve, second hot and
cold combustion responsive switches, circuit con 25
nections controlled by said load switch and sec
and cold switch for energizing said low capacity
.valve and said ignition means, an energizing cir
cuit for said burner motor controlled, by said
load switch, a high capacity fuel valve, and an 30
energizing circuit therefor controlled by said load
switch and said second hot switch.
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