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Патент USA US3100526

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Aug. 13, 1963
‘ 3,100,521
Filed Feb. 3, 1958
5 Sheets-Sheet 1
f2 410/5 01571276»?
dl/677A/ A2 051/562 ,
BY zryw’gw
Aug. 13, 1963
Filed Feb. 3, 1958
3 Sheets-Sheet 2
5/6. 4/.
JUST/N 67. 05U6’EZ,
BY Z701 W170“
Aug. 13, 1963
Filed Feb. 5, 1958
5 Sheets-Sheet 3
[5/6. 5
\ .i
L/Z/STZN 0. 054/554
United States Patent 0
Patented Aug. 13, 1963
FIGURE 1 is 1a top view of components of a control
system embodying features of the present invention.
Justin A. Deubel, Milwaukee, Wis, assignor to General
Controls (30., Glendale, Calii, a corporation of Qali
Filed Feb. 3, 1958, Ser. No. 712,853
7 Claims. (Cl. 158-125)
This invention relates generally to control systems for
gas burning domestic appliances and particularly to control
systems for domestic gas burning clothes driers. The
FIGURE 2 is a schematic illustration of the electrical
A circuit in which the components shown in FIGURE 1 are
connected. 1
FIGURE 3 is an irregular sectional view of the com
bined electromagnetic valve and relay structure embodying
features of the present invention and shown also
URE 1.
FIGURE 4 is an end view of the structure shown in
FIGURE 5 illustrates a modi?ed system.
Referring principally to FIGURES 1 and 2, there is
shown at 10 a conventional gas burner of the type used
abandoned copendin-g application Serial No. 487,785,
?led February 14, 1955, and [assigned to the same assignee. 15 on, for example, domestic ‘gas driers, the burner 10‘ and
present application is a continuation-in-part of my now
other elements being mounted on a panel 13. Gas is ad
mitted to the burner [through an inlet pipe 11, a control
valve 12, and ian inlet ?tting 14. Valve 1'2 is a solenoid
these appliances safer in operation and more trouble
operated type valve and, in accordance with ‘an import
free. As the mass market for these appliances widens,
there is a growing incentive to lower the cost of both 20 ant aspect of the present invention, is a combined valve
and relay structure with the valve and relay having a com1
the electric and gas type driers so that the competitive
mon solenoid winding for operating simultaneously the
position of one type versus the other may be bettered.
valve portion of the structure as well as the relay switches.
This has been particularly true in the case of gas burning
Mounted adjacent burner 10 is a gas ?ame sensing or
driers and it has at least been suggested that this type of
drier has more of a burden in this respect because the 25 responsive switch assembly 16, comprising a dame detector
17 and two switch arms 16A. 168 (FIGURE 2)
domestic users are convinced, correctly or incorrectly,
actuated by detector 17. The particular form of the de
that gas appliances are more dangerous than electric ap
With increased use of domestic clothes driers of both the
gas and electric type has come increased pressure to make
pliances and because more complicated and expensive
tector 17, and the linkage through which it actuates switch
control components are needed to safely control a gas ap
pliance as compared to those necessary for control of an
arms 16A, 16B are considered to be well known in the art.
In the presence of a ?ame the detector 17 causes the switch
larms 16A, 16B to move into engagement with stationary
contact 160 and to move out of engagement with sta
electric appliance.
In the past, the problem of providing for, among
tionary contact 16D respectively to close electrical circuits
other things: (1) complete gas shut-off on pilot failure
which are normally open and to open norm-ally closed
in the case of liquid petroleum gas, (2) automatic or
manual reset of the pilot safety device after a pilot failure, 35 circuits respectively, as shown, in the absence of a flame.
Also mounted adjacent burner 10, but on the opposite
(3) an interlock, either mechanical or electrical, between
side ‘from assembly 16, is a spark ignition means 20, in
the safety pilot and the manual shut-o? device to prevent
cluding mounting bracket 21, spark plug 22 with elec
“short cycling,” and (4) an electric igniter for the gas
trodes 23, 24- and lead wire 25. Lead wire 25 connects
pilot which has a satisfactory service life, have proved
troublesome. Furthermore, erratic and undepiendable 40 the electrode 24 to the ungrounded terminal of the second
ary winding of an ignition transformer 26, the outer case
operation has resulted from frequent clogging of the pilot
of plug '22 and electrode 23 being grounded in conven
burner ports as a result of operation in the lint-contami
tional manner. Mounted just below transformer 26, as
nated atmosphere adjacent a clothes drier. Various at
viewed in FIGURE 1, is a resistance element. 27, the func
tempts to solve the problem by purging of lint by the
primary air introduced into the pilot burner have not been 45 tion of which will be described hereafter with reference
to the circuit shown in FIGURE 2.
entirely successful.
A thermally timed safety switch is identi?ed by ref
An object of the present invention is to provide a spark
erence numeral 28 and is also mounted on panel 13.
ignition system for gas burning appliances, particularly
Safety switch 28 is of conventional type having 'a bimetal
clothes driers which eliminates the need for a pilot burner
contact ‘actuating arm 29 (FIGURE 2),. ‘an electric
and pilot safety devices, but provides all the safety features
thermal operator or heater 31 (FIGURE 2') for beating
heretofore associated only with systems using pilot burners
and their accompanying elaborate pilot safety devices.
the bimetal arm 29 to move such arm out of engagement
A further object is to provide a gas burning appliance
control which incorporates an ignition system having a
long, trouble-free service life.
A further object is to provide a gas burning appliance
control having spark ignition operable by means. of a
simpli?ed circuit interconnecting a simpli?ed group of con
with stationary contact 32. As is conventional with
this type of safety switch, after arm 29 has moved suf
?ciently as a result of beater 31 being energized ‘a pre
determined time, the switch 29, '32 is opened and the
arm 29 is latched there by latch 33 until manually reset.
trol components.
supported spring having its upper bent end engageable
The latch 33 is‘ illustrated in the form of .a cantilever
with the free end of arm 2?, and such upper end of the
Another important object of the present invention is to
spring latch may be moved manually away from the arm
provide a system of this character which incorporates a
29 to allow such arm 29 to move upwardly into engage
combined valve and relay structure.
ment with contact 32.
Another important object of the present invention is to
Referring now to FIGURES 3 .and 4, the valve 12 in
provide a combined valve and relay structure which is
65 cludes a valve body 34 having ‘an inlet 36 and ‘an outlet
particularly useful in control systems of this character.
37. p The valve body is mounted on the panel 13. With
The ‘features of the present invention which are believed
in the valve body there is a conventional valve seat 39
to be novel are set forth with particularity in the append
and a valve .disc 40 ‘and plunger ‘41 operated by the elec
ed claims. This invention itself, both as to its organiza
tromagnetic operator or solenoid coil 42. Coil 42 also
tion and manner of operation, together with further ob
jects and advantages thereof, may be best understood by 70 operates ‘an armature 413 which is pivoted ‘at 44 on the
generally U-shaped bracket 46. A switch actuating
reference to the following description taken in connection
member 47 is carried by the armature 43 and serves to
with the accompanying vdrawings in which:
de?ect the ?exible, contact-carrying blades 48 and 49
valve actuating rod 74 is preferably of non-magnetizable
downwardly when coil 42 is energized, as shown in
FIGURE 4. This de?ection of blades 48 and 49 serves
to close the normally open contacts ‘51A, 51B and to
material. The guide tube 65 is of non-magnetizable ma
terial such as brass.
When the coil 42 is energized the following events occur
in this order. The plunger 41 which is “?oatingly”
open the normally closed contacts 52A, 52B. ‘It is noted
that the switches 51A, 51B and 52A, 52B comprise ele
ments of a special single-pole doublethrow switch in
mounted is attracted and moves upwardly a limited dis
which switch 51A, 51B is closed before switch 52A, "52B ‘
is opened.
tance after which the upper end of the loosely mounted
spring 80 engages the lock ring 82 on the actuating mem
ber 74, after which the spring 80 is compressed and causes
' The mechanical construction of the combination valve
the plunger 74 to move upwardly with the attached closure
' and relay is now described in connection with ‘FIGURES
member 40 against the action of the relatively heavy
coil compression spring 96 disposed between the mounting
1, 3 and 4. The valve body 34 having the seat 39 has
plate 60 and the spring seat 98. Spring 80‘ serves as a
securedthereto a base plate 60 ‘by machine screws 61
with a layer of gasket material ‘62, forming a seal, in
shock absorber, to absorb a hammer-like blow and thus
terposed therebetween. Such plate ‘60 has an inturned 15
the possibility of fracturing plunger 74. This
annular ?ange portion 60A within which the annular
spring 96 normally maintained the valve closed. It is
shading ring 64 of copper and plunger guide tube 65 are
noted that because of its length and rate, spring~80l exerts
affixed as, for example, by press ?tting, welding, brazing
no force at ‘all when plunger 41 is against ring 77, as
or the like. A sleeve 67, of shorter length than the
shown. When the solenoid 42 is energized, spring 80
guide tube 65, encircles the guide tube 65 near its lower 20 develops more force than spring ‘96; otherwise, the valve
would not open. Further continued upward movement
The coil 42 is wound on spool 68 which bears on the
of the plunger results until the apertured plate 97 abuts
lower portion 46A of the generally U-shaped bracket
the annular ?ange portion 60A. The ?eld created by
46, such portion 46A being retained between the coil
coil 42 causes motion of both the valve armature 41 ‘and
form and the mounting plate 60. The upper end of the 25 relay armature 43. Both of such motions is practically
guide tube 65 is closed by a cylindrical plug 70 which
simultaneous and which occurs ?rst is not considered
is soldered in tube '65. A shading ring 72, of copper, is
important. 'When the pivoted plate 43 is attracted, it
secured to the outside of such plug 70‘ to reduce A.C.
causes the switches ‘51A, 51B and 52A, 52B to be operated
humvwh-ich is otherwise produced when the coil is ener
in‘ that order.
gized. ‘The shading ring ‘64- accomplishes this same func 30
When subsequently the coil 42 is deenergized, the spring
tion for armature ‘97 af?xed to plunger 41. It is noted
96 causes the valve 40 to be returned to closed position
that shading ring’ 72 encircles a part of plug 70 to pro
relatively rapidly and the switches 52A, 52B ‘and 51A, 51B
vide a lagging iiux path ‘for a portion of the ilux and
to be operated in that order. '
prevents armature ‘43 ‘from chattering.
The circuit which integrates all of the above described
The plunger 41 is slidably mounted in its ‘guide tube 35 components is now described with reference to FIGURE
65, and in turn, has a valve actuating element 74 slid
2. The circuit is energized by an AC. source/100 which
ably mounted in it. The element 74 in the form of a
rod has a?ixed thereto a washer 75 which is embedded
in. the closure member 40' ‘and also carries a lock ring 77
for engagement with the plunger 41.
A coil spring 30 encircles the upper end of rod 74
and is retained loosely thereon between a lock ring 82
on rod 74, and the internal shoulder ‘41A of plunger 41.
The bracketmember 46 has the aforementioned base
is connected in series with tan on-oif switch “56, a thermo
stat 101 land the bimetallic switch comprising contact 32
and bimetallic strip 29. It is understood that the thermo
stat switch 191, sensitive to temperatures in the clothes
’ drier, is closed at low temperatures and is automatically
opened at higher temperatures.
The energizing circuit for the primary winding of igni
tion transformer 26 includes the following elements that
portion 46A and upstanding plate portions 46B and 45 are connected in series, namely, source 100, switch 56,
46C, each of which are provided with deformable lugs
thermostat ltil bimetallic switch 29, 32, switch 16B,_'1‘6D,
46E ‘for securing the insulating switch carrying plate 84.
resistance 27 and “the primary winding of transformer 26;
This plate has riveted thereto the switch terminals 86,
The switch 16B, 16D comprises an element of the ?ame
87 and 88. Switch'terminal 86 carries the leaf spring
switching means 16 which is illustrated in
49 which carries the contacts 51B and 52B. Terminal‘ 50 FIGURE 2 in its cold position.
87 carries the leaf spring 48‘ which carries the contact
The initial energizing circuit for the solenoid coil 42
5-1A.. Terminal 88 carries the ‘contact 52A. It is thus
comprises the following elements which are connected in
seen that the switch assembly (with the exception of its
series, namely, source 100, switch 56, thermostat 101,
actuating member 47) is carried on the single plate 84.
bimetal switch 29, 32, switch 16B, 16D, switch 52A, 52B,
The switch actuating member 47 of insulating material
heater 31 and coil 42. Switches 52A, 52B and 51A, 51B
extends ‘from a small bracket 93 mounted on the pivoted
armature plate 43. This bracket ‘93 has a downwardly
and outwardly extending portion 93A that is arranged
to abut against the bracket portion 46E which ‘acts as
a stop in ‘limiting pivotal movement of plate 43.
i The plate 43 is normally biased so that these elements
93A, 46B are in engagement by the prestressed coil ten
are illustrated in the normal positions they assume when
the solenoid 42 is de-energized; and these switches, ‘as is
seen from the description of vFIGURE 4, comprise essen
tially a single-pole double-throw switch in which, upon
energization of coil 42, the switch 51A, ‘51B is closed
before switch 52A, 52B is opened. It is noted that the
switch contact ‘51A is connected to the movable swtich
clement 16B and also to one terminal of the bimetal strip
apertured portion of plate 43 and the other one of its 65 29. Switch contacts 51B and 52B are each connected
ends hooked around one of the fastening lugs 46E. The
to one terminal of the heater ‘31 and also to the movable
sion‘ spring 96 having one of its ends hooked into an
plate 43 is conveniently retained in pivoted relationship
on bracket portion l46A by spaced extensions of such
switch contact 16A.
plunger 41, plug 70, plate 43, U-shaped bracket 46 in
cluding 46A and mounting plate 60, and the apertured
circuit with heat-responsive switch v‘16B, 16D and that
plate 97’- a?ixed‘ on the lower end of plunger 41.
its normally open relay switch 51A, 51B and that the
The switch comprising elements 16A and 16C is con
bracket portion passing through spaced open-ended slatted
nected in’ parallel with the heater 31 for purposes of short
portions of plate 43.
70 circuiting the same in the “hot” condition of switch 16‘.
The ‘following elements are of magnetizab-le material
It will be observed from the following detailed descrip
so .as to achieve the desired magnetic attract-ion; namely,
tion that the ignition means 26 is connected in a ?rst series
the solenoid 42 is connected in a second series circuit with
other normally closed relay switch ‘52A, ‘52B intercon
nects junction points in these two series circuits; and that
since the switch 168, 16D is open and thus there cannot
be a current ?owing either in winding ‘42 or the primary
these two series circuits are separate branches of a parallel
winding of ignition transformer 26. This is likewise true
circuit energized from source r100‘. Speci?cally, such ?rst
should the on-oif switch 56 be momentarily opened and
series circuit, is. parallel branch, extends from bimetal 5 then closed.
element 29 through switch 16B, 161), resistance 27 to the
Thus, if at the end of a cycle of the burner the
primary winding of the ignition transformer 26; such sec
?ame detector 17 should fail to turn to its. cold position,
switch 16B, 16D remains in open position and will pre
ond series circuit, i.e. second parallel |bnanch, extends from
the same bimetal element 29 through normally open relay
vent the start ofv a new “on” cycle. Switch 16B, 16D
switch 51A, 51B through switch element 52B, and through
thus provides a check, at the end of each “on” cycle, as
to the proper functioning of the ?ame responsive switch
heater 31 to the solenoid coil 42; and the normally closed
ing means 16. From this it will also be observed that
relay switch 52A, 52B interconnects junction points in
if in the midst of a normal “on” cycle the control circuit
these two series or branch circuits, the junction point in
should be momentarily de-energized as, for example, by
such ?rst series circuit being the interconnection between
stationary contact 16]) and resistance 27 and the junction 15 momentarily opening ‘and then closing switch 56, such
reclosure of switch 56 will not cause gas to flow without
point in such second series circuit being the switch element
ignition because winding 42 can initially only be ener
‘523. Further, these two series or ‘branch circuits are
gized through switch 163, 16D and switch 52A, 52B.
energized from ‘source 100 having one of its terminal
The interlock provided by switch 51A, 51B assures that
connected directly to a terminal of the primary winding of
ignition transformer ‘26 and to \a terminal of the solenoid 20 gas cannot be ‘admitted to burner 10 until the ?ame
switch 16 has assumed its cold position and switch 16B,
coil 42, the other terminal of source 100 being connected
16D connected the igniter in the energizing: circuit.
to the aforementioned bimetal element 29 through switch
Also, if the switch 52A should ?ail to close after the
56, thermostat 101 ‘and bimetal contact 32.
end of the heating cycle, the start of a new “on” cycle
The operation of the circuit shown in FIGURE 2 is
essentially as follows. Assuming that the drier has been 25 is prevented, i.e., gas is prevented-from ?owing since
the energizing circuit for coil 42, which includes switch
out of operation for a considerable length of time and
52A, is open.
is cold, the thermostat 101 is closed. At this time when
Further, if there is malfunctioning of the ?ame de
the on-o? switch 56 is closed, both the primary winding
tector 17 during the initial portion of the “on” cycle
of transformer 26 and the solenoid coil 42 are energized.
such that, for any reason whatsoever, the switch 16A,
Such primary winding of transformer 26 and winding
16C is not closed, then the heater 31 will become suf
42 are at this time energized through a circuit which in
?ciently heated to cause the switch 29, 32 to open and
cludes source 100‘, switch 56, thermostat 101, switch 29,
be maintained in latched position by the latch 33. In
32, switch 16B, 16D, the primary winding being ener
this case, manual openation of the latch 33, i.e., reset
gized through current limiting resistance 27, and the
coil 42 being energized through switch 52A, 52B and 35 means, is required before either the solenoid 42 or spark
plug 20 may again be energized.
heater 31. At this stage a gas igniting spark exists at
Also, if the switch 16B, 16D should not return to
the spark plug 22 for igniting the gas which now ?ows
its closed position after a heating cycle, gas Will be pre
as a result of the coil 42 being energized. When coil 42
vented from ?owing, as indicated previously, due to the
is energized, the switch 51A, 51B is closed before switch
fact that the energizing circuit for coil 42, which includes
52A, 52B is opened and such switch 51A, 51B remains
the switch 16B, 16D, is open.
closed so that the winding 42 remains continuously ener
The switch elements 16A, v16B are mechanically inter
gized without such energizing current passing through
locked so as to assume simultaneous operation of the
switch 16B, 16D. In other words, energization of the
same and to assure their relative positions ”one with re
coil 42 at this particular time is independent of the hot
or cold condition of the heat responsive switching means 45 spect to the other and associated stationary contacts so
that, for example, should switch 16A, 160 be closed to
16, and gas continues to ?ow. Should there be no igni
short circuit heater 31, the switch 16B, 161D is assured
tion of such gas for a predetermined time interval, the
of being open to prevent energization of solenoid 42.
heater 31 becomes suf?ciently heated so as to cause the
If during a heating cycle, there be a ?ame failure,
bimetallic strip 29 to deflect downwardly in FIGURE 2
and to open the switch 29, 32. Should this condition oc 50 the switch ‘16 returns to its position as shown in FIG
URE 2, in which case, switch 16A, 16C is open to re
cur, the bimetallic strip is latched in its circuit opening
move the short circuit across heater 31 to, in turn, cause
position by the‘latch 33; and such switch 29, 32 may not
the switch 29, 32 in the main energizing circuit to open
return to its closed position until the safety switch 28
and thus the fuel solenoid 42 is deenergized and the flow
is manually reset by manual operation of the latch 33.
55 of fuel to the burner is stopped.
Assuming, however, that gas ignition has been success
In the modi?ed arrangement shown in FIGURE 5,
fully ‘accomplished within such predetermined time in
the dryer motor 102 which rotates the conventional drum
terval, the flame detector 17 is heated and switching
of a dryer is energized through switch 105 and normally
means 16 is operated and consequently switch 16A, 16C
is closed and switch 16B, 16B is opened. Closing of 60 closed limit switch 156 when the knob 106 of the con
ventional motor driven timer :107 is moved from its
switch 16A, 16C results in short-circuiting of the heater
“zero” time position to a presettable time. The switch
31; and opening of switch 16B, 16D breaks the energiz
156 is of conventional construction for the conven
ing circuit for the primary winding of ignition trans‘
tional purpose of de-energizing the dryer circuit when
former 26.
excessive temperatures are produced in the dryer and is
After the drier has reached a predetermined tempena- ,
mounted in the dryer in a conventional position where
ture established by the condition of thermostat 101, thej_
switch in such thermostat 101 opens, thereby opening ‘ excessive temperatures might possibly result, all in ac
cordance with prior art teachings. After the elapse of
the energizing circuit for the solenoid winding 4-2; and
such presettable time interval, the switch 105 as well as
when such winding 42 is tie-energized the switches 51A,
51B and 52A, 5213 return to their positions shown in 70 the other timer operated switch 108 is allowed to return
to their open positions. The ‘connection between the
FIGURE 2, and the ?ame detecting means is no longer
timer 107 and its switches 105 and 103 is indicated by
being heated. In the event that the thermostat switch
the dotted lines 109 and 110. The circuit shown in
101 is closed while the heat responsive switching means
FIG. 5 is now described under the conditions existing
16 is still in its hot condition, there is neither a ?ow
when switches 105 and 108 are closed.
of gas nor an ignitingspark at spark plug 22. This is so 75
When switch 108 is initially closed, the primary wind
switch 129, 132 is opened, thus requiring manual re
ing 126A of the ignition transformer 126 is energized
to produce a fuel igniting spark at ignition plug 120,
such winding 126A being energized from source 1111,
152A, 152B (like switch 52A, 5213 in FIGURE 2) opens
closure of switch 108. During the time that switch 116B,
Switch 129, 132 opens upon malfunctioning of the sys
tem’ under,’ for example, the‘ following conditions:
switch 1156, switch 108 and the normally closed switches
Should there be ?ow of unignited fuel from the pilot
1116B, =‘116D and 129, :132. The switch 116B, 116D
burner 139A or should there be insufficient ?ow of ig
as well as the switch 116A, 1160 are operated by the
nited fuel from the same burner 139A, the switch 116B,
?ame sensing element 117 which may comprise a heat
116D will not open and the heater 131 is heated su?i
sensitive ?ame rod, like the ?ame rod 117 in FIGURE 2,
ciently to open the safety switch 129, 132. In such case
as indicated by the dotted lines 112. The switch 129,
a 132, like the switch 29, 32 in FIGURE 2 is a safety 10 the heater 131 is heated by current ?owing through a
series circuit which includes source 111, switch 156,
switch which is opened only after the associated heater
switch 108, switch 116B, 116D and heater 131. The
131 is heated for a predetermined time interval. The
same result is obtained should the ?ame rod 117 become
relationship between the heating element 131 and the
inoperative under normal pilot burner conditions; i.e.,
bimetallic switch element 129 is represented by the dotted
line 114. Also, at this time, the “A” fuel valve sole 15 should the ?ame rod fail to open switch 116D.
It will be seen from this that proper functioning of the
noid winding 142 is energized from source ‘111 through
?ame rod 117 is checked at the beginning of each dry
switch 156, switch 1108, switch 1116B, 116D, relay switch
ing operation and if there is failure, all gas will be cut
152A, ‘152B and switch 129, 132 so as to open the
off and manual resetting is required.
fuel valve 39, 40, such winding 142 (like winding 42
in FIGURE 2) comprising the operating winding for 20 In case of power failure of short duration, occasioned
by opening and closing of the line switch represented by
solenoid-type fuel valve 39, 40 which controls the ?ow
the switch 108 or the switch 156, for example, during ‘a
of fuel to pilot burner 139A; and this relationship is indi
heating cycle, the pilot solenoid 142 and main ‘burner
cated by the dotted line 142A. When the winding 142
solenoid 139B rare deenergized to prevent fuel ?ow. Upon
is thus energized, the normally closed relay switch 152A, 152B is opened, the normally open, relay switch 151A, 25 initial reclosure of switch 108 or switch 156,’ neither sole
noid 142, nor solenoid 1393 will be energized since some
151B is closed and the third relay switch; namely, relay
time is, required for the ?ame rod 117 to cool to su?i‘oient
switch 152C, which is normally open, is closed as is
degree to allow switch 116B, 116D to return to closed
indicated by the dotted lines that interconnect these
position. Switch 116B, 116D upon reclo‘sing institutes a
switches with the winding 142. Switch 151A, 151B (like
switch 51A, MB in FIGURE 2) closes before switch 30 new cycle of events as described above in connection with
so as to assure an energizing circuit for winding 142,
116D is returning towards closed position, under these
subsequently, after the heat responsive switch 1163,
conditions, the dryer motor is rotating since it is assumed
that the timer switch 105 remains closed.
M61) is opened. Closure of such third relay switch 152C
It will be observed also that safety switch 129‘, 132 will
conditions an'energizing circuit for the “B” fuel valve 35
be opened in the event of failure of the relay switch 152A,
solenoid winding 13913 which controls the ?ow of fuel
152B to be properly operated, since if it remains in closed
to the main burner 139. At this stage, the gas ?owing
position with solenoid 142 energizedya heat circuit for the
from the pilot burner 139A, which has been ignited by
heater 131 is established through switches 151A, 151B
the spark produced by the plug 120 burns and heats
the ?ame rod 117' and after it has been heated to a suffi 110 and 152B, 152A; and if switch 152A, 152B fails to return
to closed position, the solenoid 142 will not become ener
ciently high degree, i.e., after some time, its associated
gized and thus heater 131 will be heated suf?‘ciently
normally closed switch 116B, 116D opens and switch
through switch 116B, \116D to cause safety switch 129,
1116A, 116C closes. Opening of switch 116B, 116D
132 to open.
serves. to deenergize the ignition transformer 126; and,
The valves included in the system shown in FIGURE 5
closure of switch 116A, 116C further conditions the en
and having the solenoid windings 1:42 and 1393 are con
ergizing circuit for main burner solenoid winding 139B.
sidered to be constructed both mechanically and mag
In fact, in the cold condition of the dryer, closure of
netically essentially as shown in FIGURE 3.
switch 116A causes the winding 139B to be energized
It will be observed that the arrangement shown in FIG
through a circuit that includes: switch 156, switch 1108,
switch '116A, 1160, switch 152C and thermostatic ele 50 URE 5 may be used without the manual reset latch 133.
This is so since heater 131 remains energized so‘ long as
ment 160A and thermostatic switch 160 which. is oper
switch 116B, 116D is closed. Such switch will‘ serve to
ated by the thermostatic element 160A. The gas issuing
hold the switch 129, 132 open until electric power is
from the main burner 139is ignited by the ?ame from
removed in the event of ignition or ?ame failure condi
the pilot burner 139A and the dryer chamber is thus
tions. With this arrangement, the drier, under ?ame fail
heated. Should the temperature in the dryer chamber
ure or ignition failure conditions, completes its normal
exceed a predetermined temperature established by the
drying time cycle without the burners coming on. Power
setting of thermostatic element 16A, switch 169 is then
is subsequently turned off by the motorized switches i105
opened to deenergize winding 139B and thus cut off the
and 198 :and when such switches are automatically opened
?ow of fuel to the main burner 139. Should, thereafter,
the temperature in- the dryer chamber fall below said 60 after the timed cycle, the warp switch 129, 132 is reset
automatically during the power “off” time and thus is
predetermined temperature, switch ‘160 is reclosed and
ready for a new start when power is restored upon manual
fuel again is allowed to ?ow from the main burner 13-9
operation of knob 106. It will be observed that in the
for ignition by the pilot burner ‘139A. After an elapse
arrangement shown in FIGURE 5, the heater 1131 is con
of time established by the setting of the motor driven
timer 107, the switches 105 and 108 open and the system 65 nected in parallel with the warp switch 129', 132 and in the
~ event of the heater i131 burning out, the warp switch
is deenergized; i.e., all ?ow of fuel is interrupted in
‘action provided by the bimetal element 129 is not effected.
cluding that to the pilot valve operating solenoid 142.
In the arrangement shown in FIGURE 2, the heater
It will be observed from the foregoing that opening
is wired in series with the combination relay ‘and valve
of the safety switch 129, 132, for any reason, will “shut 70 and in the event the heater burns out, the valve will not
down” the system since, in such case the pilot solenoid
be energized and hence the system fails safe.
142 and the ignition transformer 126 are deenergized.
While the particular embodiments of the present in
This safety switch v129, 132 comprises the bimetal ele
vention have been shown and described, it will be obvious
ment 129 which is heated by the resistor 131 and which
to those skilled in the art that changesv and modi?cations
is latched in open position by the latch 133 when the 75 may be made without departing ?ronr this invention in
its broader aspects and, therefore, the aim in the appended
sponsive switch; a heating element for operating said
claims is to cover all such changes and modi?cations as
fall within the true spirit and scope of this invention.
I claim:
1. A control system for a gas-‘burning appliance, a main
burner, a spark igniter for the main burner, a valve con
trolling the ?ow of gas to said burner, tan electromag
switch; ?ame actuated switching means including a ?rst
normally closed switch and a second normally open
switch; said second switch being connected in shunt with
said heating element; igniting means; fuel control means
serially connected with said heating element; a single-pole
double-throw switch operated when said fuel control
netically operated switching mechanism and an electro
means is energized; said single-pole double-throw switch
magnetic operator which operates said valve and said
having a movable contact connected serially with said
switching mechanism, I3. ?ame responsive switch mecha 10 heating element and said fuel control means; a ?rst contact
nism having a ?rst switch closed only in the absence of
of said single-pole double-throw switch being connected
?ame at said burner and 1a second switch closed only on
both to one terminal of said ?rst normally closed switch
the presence of ?ame i211 said burner, a safety switch hav
and- also to one terminal of said igniting means; the other
ing a thermal operator adapted to move said safety switch
terminal of said ?rst normally closed switch being con
from closed to open position 1a predetermined time after 15 nected to one terminal of said heat responsive switch; a
energization of the thermal operator, a circuit network
second contact of said single-pole double-throw switch
comprising said safety switch and said ?rst switch con
being connected directly to said one terminal of said heat
nected in series with each other and with two parallel cir
responsive switch; the other terminal of said heat re~
cuit branches, one of said branches connecting in series
ponsive switch being connectible to one terminal of a
the thermal operator for said safety switch and the op 20 source of energizing current; the other terminal of said
erator for said valve, the other branch including said spark
igniting means being connected to the other terminal of
igniter, control switch means connecting said circuit net
said energizing source; and said movable contact of said
work across a source of power, said second switch serving
single-pole double-throw switch being connected to said
other terminal of said energizing source through said heat
at the burner before said predetermined time has elapsed, 25 ing element and said fuel control means.
said network being adapted upon closure of said control
5. A system as set forth in claim 4 in which said single
switch to initially energize said valve operator, the spark
pole double-throw switch is of the make before break
igniter, and said safety switch operator ‘and, upon the
appearance of ?ame at said burner, to tdeenergize said
6. In a control system of the character described for
igniter and to retain said valve operator energized, and
controlling the ?ow of gas to a burner, ‘a gas igniting
circuit means including said ?rst switch ‘for preventing said
means for igniting gas at said burner, a normally closed
main valve from re-opening upon momentary lde-ener-giza
head responsive switch which is opened by heat developed
tion of said valve operator while said ?ame responsive
by the burner, said switch and igniting means being con
switching mechanism remains in hot condition, said circuit
nected in a ?rst series circuit, a solenoid valve including a
means including a normally closed switch of said electro
coil for controlling the ?ow of gas to said burner, said
magnetically operated switching mechanism which con
' valve ‘being opened when said coil is energized, a pair of
trols energization of said valve operator and a normally
relay switches actuated upon energization of said coil, one
open switch of said electromagnetically operated switch
of said pair of relay switches being normally open and
mechanism shunting said ?rst switch and said last named
actuated to closed position when said coil is energized, a
normally closed switch.
40 second series circuit which includes said one relay switch
2. A control system for gas burning apparatus com
and said coil connected in series, said heat responsive
to deenergize said thermal operator when a ?ame appears
prising: an energizing source ?ame responsive means in~
switch being connected to said igniting means at a ?rst
junction point, said one relay switch being connected to
said coil at a second junction point, the other of said pair
mally closed switch, each of which is operated in response
to heat from the ?ame; fuel control means including an 45 of relay switches being normally closed and serving to nor
cluding a ?rst normally open switch and a second nor
operator therefor; a third normally open switch and a ,
mally interconnect said ?rst junction point to means con
fourth normally closed switch, said third and fourth
switches comprising single-pole double-throw switching
necting said second junction point, said ?rst and second
switch; said second series circuit including serially said
source, said ?fth, second and fourth switches, said safety
switch is opened.
series circuits in parallel with each other to form two
means and being operated upon actuation of said fuel con
parallel branches, and an energizing source connected to
trol means by said operator; safety switching means in 50 each of said branches to produce a current ?ow through
cluding a normally closed ?fth switch which has associated
said igniting means in the normal position of said heat
responsive switch and to produce a current ?ow through
therewith an actuator for actuating said ?fth switch; ignit
said coil alternately through said one and the other relay
ing means; current limiting means; a ?rst series circuit
including serially said ?fth switch, said second switch, said
current limiting means and said igniting means; a second 55
7. A system as set forth in claim 6 in which said pair
series circuit connectible in parallel with said current
of relay switches are of the make before break type in
limiting means and said igniting means by said fourth
which said one switch is closed before said other relay
switch actuator and said operator; said first switch being 60
connected in shunt with said actuator; and said third
switch being effective to connect said operator directly to
said safety switch through said ‘actuator such that said
second serial circuit may be energized with current ?owing
through said safety switch regardless of the condition of 65
said second switch.
3. A system as set forth in claim 2 in which said single
pole double-throw switch is of the make before break type
in which said third switch is closed before said fourth
switch is opened.
4. In a system of the character described, a heat re
References Cited in the ?le of this patent
Shivers ______________ __ Mar. 26, 1929
Kaufmann ___________ __ Feb. 26, 1946
Ogden _______________ __ Aug. 20, 1946
Nycum et al. _________ __ Nov. 13, 1951
Caparone ____________ __ Aug. 19, 1952
Duebel ______________ __ Ian. 10,
Morrison ____________ __ July 23,
Pinckaers ____________ __ June 17,
Flagg ________________ __ Jan. 27,
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