US2869633A

US2869633A - schaaf e

Info

Publication number: US2869633A
Authority: US
Publication date: 1959-01-20
Anticipated expiration: 1976-01-20

Description

Jan. 20, 1959 w. A. SCHAAF ET AL PILOTLESS IGNITIO N DEVICE AND SYSTEM FOR TH SAFE IGNITION OF GASES AND VAPORS N wf Filed July 18, 1955 INVENTOR5 WILLARD ARTHUR CHAA-F United States Patent O M PILOTLESS lGNITION DEVICE AND SYSTEM FOR THE SAF E IGNITION OF GASES AND VAPORS Willard Arthur Schaaf, Coloma, and Lewis Edward Simes II, Lawrence, Mich, assignors, by mesne assignments, to Whirlpool Corporation, a corporation of Delaware Application July 18, 1955, Serial No. 522,559

11 Claims. (Cl. 158--128) This invention relates to improvements in safety meth' ods and apparatus for the direct ignition of gas burners by an electric arc.

A principal object of our invention is to provide a simple and novel device and method for the safe ignition of gases and vapors in which no pilot burner is required.

Another object of our invention is to provide a novel form of electric igniter for igniting vapors and gases on normal line voltage.

Still another object of our invention is to provide a simple and efficient method and apparatus for the safe ignition of gas burners without the use of the usual pilot burner, in which the igniter consists in two arcing contacts normally engaging each other to complete an energizing circuit and moving apart to provide an arc by resistor heat generated upon energization of an energizing control circuit for the burner.

Still another object of our invention is to provide a simplified method and apparatus for igniting the gas flowing from a main gas burner so constructed and arranged as to obviate the necessity for the high igniter voltages heretofore required, and to effect a spark for igniting a burner by the moving apart of two arcing contacts, the energizing circuit for the arc of which is at normal line voltages.

A still further object of our invention is to provide an igniter for gas burners and the like in which the gas is ignited by an arc and in which the gas burner is supplied with gas under a safety control energizing circuit becoming energized by separation of the arcing contacts.

A still furtherobject of our invention is to provide an igniter circuit particularly adapted to ignite gas burners and the like in which the arcing contacts are carried on bimetal resistors and are normally in engagement with each other, to complete a circuit through the resistors and effect warping thereof to separate the contacts to attain an arc therebetween.

These and other objects of our invention will appear from time to time as the following specification proceeds and with reference to the accompanying drawings wherein:

Figure l is a diagrammatic view diagrammatically illustrating a form of ignition device and safety gas burner circuit constructed in accordance with our invention; and

Figure 2 is a view somewhat similar to Figure l and illustrating a modified form in which our invention may be embodied.

In Figure 1 of the drawings we have shown an electric igniter of a type which may be elfectively used for a gas burner 11 which may be for a gas heated clothes drier of a type in which the clothes are dried by tumbling and the circulation of heated air through a tumbling drum (not shown) as shown in Patent No. 2,635,354, which issued to Peter Eduard Geldhof and Harold E. Morrison on April 21, 1953, and not part of our present invention so not herein shown or described further.

The spark igniter 10 is shown as comprising two

arcing contacts

12 and 13 on bimetal resistor arms 15 and 16,

2,869,633 Patented Jan. 20, 1959 respectively, and normally engaged with each other and moving apart to effect an arc to ignite the burner 11 without the need for the usual pilot burner.

The igniter 10 may be located in a gas burner tube structure 14, upstream of the end of the burner itself, in a position where it is cooled by the gas stream after ignition takes place and burning occurs at the end of the burner tube structure.

The bimetal resistor arms 15 and 16 may be so constructed and may be made of such materials that the flow of current through said arms will cause heating of the arms, as by the resistor heat generated therein, effecting separation of the arms by warping to separate the

arcing contacts

12 and 13 to attain an are or spark.

The arms 3.5 and 16 are normally energized through main line conductors 17 and 19, when a burner valve 20 controlling the supply of gas to the main gas burner 11 is off. The conductors 17 and 19 may be connected with a suitable source of power at normal household line voltages and provide an energizing circuit to the

arcing contacts

12 and 13 through the contacts of a timer switch 21, which may be of a conventional form operated by the usual timer motor (not shown). Engagement of the contacts of the timer switch 21 closes an energizing circuit from the conductor 17 to the conductor 19 through a safety thermostat 22, an adjustable thermostat 23 and a current limiting resistor 24, which is designed to act as a fuse to break the circuit in case of a short circuit for example across the igniter device leads.

The safety thermostat 22 and the adjustable thermostat 23 may be of forms well known to those skilled in the art so need not herein be shown or described further. The current limiting resistor may be provided to limit the current passing through the control circuit to the desired predetermined value, dependent upon the voltage of the circuit and the current required to effect a suflicient spark to ignite the main gas burner 11 and energize a solenoid 25 for the main gas burner valve 20, to open said valve and hold said valve open, as long as the burner 11 is ignited and the timer switch 21 is closed.

The bimetal arm 15 is shown as being connected with the current limiting resistor 24 as by a conductor 26. The bimetal arm 16 is shown as being connected with the conductor 19 as by conductor 27, a cold contact 29 of a flame detecting switch 3d, a switch arm 31 of said flame detecting switch, a conductor 32 connected with said switch arm and a normally closed time delay warp switch 33 opening by resistor heat in a time delay interval sufficient to prevent a dangerous accumulation of gas should the valve Zii be open and the burner 11 fail to ignite.

The flame detecting switch 38 may be a conventional form of thermally operated switch operated by a hot wire or a thermal bulb (not shown) adjacent the burner and containing a liquid, which moves the contact arm 31 from a position in engagement with the cold contact 29 into engagement with a hot contact 35 by the heat of the burner flame, as is usual with such switches.

The flame detecting switch 36 thus serves to cut the igniter 10 out of the circuit after ignition takes place and to break the entire circuit if the burner should fail to ignite, as will hereinafter more clearly appear as this specification proceeds.

The time delay warp switch 33 may also be of a conventional form and is herein shown as including a bimetal arm 36 normally engaging a stationary contact 37. A resistor 39 disposed adjacent the switch arm provides heat to open said switch after the

contacts

12 and 13 have been opened a sufficient time to normally ignite the burner 11, should the burner fail to ignite. The resistor 39 is connected in series with the solenoid coil 25 arcing

contacts

12 and 13 with each other.

,gization of the solenoid coil 25.

for the main burner valve'Ztl and is energized upon opening of the

arcing contacts

32 and 13 to warp the bimetal switch arm 36 out of engagement with the stationary contact 37 in a predetermined delayed time interval.

The solenoid coil 25 for the burner valve is shown as being connected in parallel with the bimetal resistor arms and to and the

arcing contacts

32 and 13 through a conductor 41 connected with the current limiting rcsistor 24, the conductor iii, the resistor 39 for the warp switch 33, a movable contact arm 4-3 of a relay 44, a stationary contact 45 of said relay and a conductor 4t? connected with the cold contact 29 of the flame detector switch 30.

When, however, the timer switch 2?; is closed and the

arcing contacts

12 and 13 are in their normally engaged position the energizing circuit through the solenoid coil 25 and coil 39 of the warp switch 33 will be substantially shorted out of the circuit by the arcing contacts 22. and 13, and no appreciable current will pass through the solenoid coil 25 for the main burner valve 2t? and the resistor or heater 39 for the warp switch 33.

The main burner valve 2! will thus remain closed when the arcing contacts and 13 are in engagement with each other and the switch arm 31 of the flame detector switch 39 is in engagement with the cold contact 29 thereof. The bimetal resistor arms 15 and to will then heat up quickly by resistor heat. This will effect rapid warping of said switch arms in directions to separate the contacts 12 and E3 and cause arcing between said contacts. The main gas burner valve, however, will remain closed during this arcing since the solenoid 25 has not been energized due to the short circuit across the

arcing contacts

12 and 13.

As the

arcing contacts

12 and 13 separate by warping of the bimetal resistor arms 15 and in effected by resister heat, said arcing contacts will move apart to a point where the circuit through the conductor 26 to the conductor 27 and main line conductor 19 will be broken. Current will then flow through the conductor d1 and solenoid coil 25 and through the resistor 39, switch arm 43 of relay 44, contact 1-5, contact 29 of the flame detector switch 3%, contact arm 31, conductor 32 and warp switch 33 to the conductor 1? Energization of the solenoid 25 will open the main burner valve 2t? to supply gas to the burner 11 and will also effect the actuation of the relay 44. This will move the movable contact arm out of engagement with the contact 45 into engagement with a stationary contact 47. The solenoid coil 25 will then be held energized through the contact arm 43, contact -ll, a conductor 49 and the warp switch 33 connected with the conductor 19.

As the valve 2 opens, the bimetal resistor arms 15 and 16 will have cooled rapidly and sufllciently to engage the During this short period of contact of said arcing contacts, the coil 25 and heater coil 39 will again be shorted out of the circuit for a very brief interval only. The valve 2%, however, and relay 44 do not instantaneously close, and the valve 2t) will remain open for the very short period the

contacts

12 and 13 are closed prior to ignition of the burner 11. Resistor heat will then quickly warp said arms to move the contacts 12 and t3 apart and effect an arc to ignite the gas issuing from the valve 29 so that combustion takes place at the burner 1%..

The relay 44 may be a well known form of relay or switch operated upon energization of the solenoid coil 25 and may preferably be operated by an armature 5% of the solenoid, which opens the main burner valve 2 upon energization of the solenoid 25. The relay 4-4 may also include a switch arm 51 connected to operate with the switch arm 43. The switch arm is herein shown as being connected in the conductor 4% and as being movable from the solid line position shown in Figure l to the dotted line position shown in this figure, upon enerin this position, the

switch arm 51 engages a stationary contact 53. The contact 53 is connected with the hot contact 35 of the flame detector switch 30 through a conductor 54.

Thus upon energization of the solenoid coil 25 and opening of the main burner valve 21), the switch arm 51 will move into engagement with the stationary contact 53 to partially complete a holding circuit to the solenoid coil 25 up to the hot contact-35 of the flame detector switch 30'. The switch arm 43 will also move into engagement with the contact 47, as previously described.

The relay 44 thus initially connects the cold contact 29 of the flame detector switch 30 in series with the solenoid 25 to energize said solenoid upon the initial separation of the

contacts

12 and 13, and thus to open the valve 26 to supply gas to the burner 11. The relay 44, upon energization of the solenoid 25 then operates to connect the solenoid 25 directly in series with the warp switch 33 and its heater resistor 39, as the burner is ignited, and to by-pass the resistor 39 upon movement of the flame detector switch to close a circuit through its hot contact 35 by the heat of the burner flame. The relay 44 thus assures that the solenoid 25 will either be in series with the resistor 39 for opening the warp switch 33 or with the hot contact 35 of the flame detector switch 39, to assure opening of the circuit to the solenoid 25 and the deenergizing of said solenoid either upon failure of the burner to ignite, failure of the gas supply causing the burner to go out, or in cases where the energizing circuit may be deenergized and current may be turned back on again.

As gas passing from the burner valve 2% is ignited by the spark attained by separation of the

arcing contacts

12 and 13, the heat of the burner flame will efiect movement of the switch arm 31 of the flame detector switch 3i) out of engagement with the stationaly contact 29 into engagement with the hot contact 35 of said flame detector switch. At this time the switch arm 51 will be in engagement with the stationary contact 53 and the switch arm 43 will be in engagement with the stationary contact 47. The circuit through the

arcing contacts

12 and 13 will also be broken and said arcing contacts will come into engagement with each other and stay in this engaged position since they are positioned in and cooled by the gas stream. The main burner valve 20 will then be held open through the switch arm 51, contact 53, conductor 54, hot contact 35 of the flame detector switch 30, contact arm 31 of said flame detector switch and the warp switch 33.

In this condition of operation of the burner circuit,-the resistor 39 for the warp switch 33 will be by-passed and the warp switch 33 will remain in its closed position to maintain the solenoid coil 25 energized and the burner valve 2t) open as long asthe burner is lit and the circuit is energized.

If, however, the burner 11 should go out as by a gas failure, the flame detector switch 361 will cool and the contact arm 31 thereof will move out of engagement with the hot contact 35 of said flame detector switch into engagement with the cold contact 2% of said switch. The arcing

contacts

12 and 13 being closed, the solenoid coil 25 and resistor 39 will again be shorted out of the circuit for a very short interval until the arcing contacts open. The valve 20 will not close immediately, and the relay 44 will not operate immediately as before discussed to disengage the switch arm 51 from the contact 53 and to engage the switch arm 43 with the con tact 45, but the continued current passing through warp switch heater coil 39 will cause the warp switch 33 to open to break the entire circuit shutting oif all operation until later manually reset.

It should here be noted that when the resistor 39, operating the warp switch 33, becomes shorted out of the circuit, that the solenoid 25 will then be energized through the hot contact 35 of the flame detector switch 30 and will then be protected by said flame detector I aasaess switch, the contact arm 31 of which opens the circuit through the. hot contact 35 should .the current be turned off, or should there be a failure in the gas supply, and immediately places the resistor 39 in the circuit in series with the solenoid 25 to open the warp switch 33 and deenergize the solenoid 25, in case the burner should be out for any reason. The energizing circuit to the solenoid 25 is, therefore, always a series circuit through the timer 21, safety thermostat 22, adjustable thermostat 23, current limiting resistor 24, resistor 39, cold contact 29 of the flame detector switch 30, contact arm 31 and warp switch 33, prior to ignition of the burner and through the hot contact 35 of the flame detector switch andwarp switch 33 upon ignition of the burner, the warp switch 33 serving to deenergize the solenoid 25 whenever the movable contact arm 31 is out of engagement. with the hot contact 35 of the flame detector switch.

The flame detector switch 30 further cuts the igniter out of the circuit after ignition takes place and also serves to by-pass or shunt the resistor 39 out of the circuit after ignition has taken place, to avoid deenergizing the solenoid when the burner 11 is lit, and immediately places the resistor 39 in the circuit to open the warp switch 33 should the burner go out. The flame detector switch thus conditions the entire circuit to be deenergized, if no ignition should take place after suitable time delay or if the burner should go out as by the failure of the gas supply or by the turning off of the energizing circuit and then turning it back on again. In the modified form of our invention illustrated in Figure 2 the timer switch, safety thermostat, adjustable thermostat, igniter and flame detector switch are similar to those shown in Figure l. The same part numbers will,therefore, be applied to these similar parts as were applied to the form of our invention illustrated in Figure 1. In the modification of our invention shown in Figure 2, we have eliminated the relay switch arm 51 and the stationary contact 53 and instead have provided a warp switch having two resistor heater windings 61 and 62, which may be wound one within the other and insulated from eachother, or may be of any other arrangement desired. The resistor winding 61 is connected with a solenoid coil 63 for the solenoid for operating the main burner valve 20, through a switch arm 64 and stationary contact 65 of a relay 66, operated upon energization of the solenoid coil 63. The resistor 61 is also connected with the conductor 27 through a conductor 67. The resistor 62 is connected with a stationary contact 69 of the relay 66 and with the conductor 32 connected from the movable switch arm 31 of the flame detectorswitch to the conductor 19 through the time delay warp switch 60.

Thus when the timer switch 21 is closed an energizing circuit is completed through the bimetal resistor arms 15 and 16 and the arcing

contacts

12 and 13 thereof. In this condition of operation, a short circuit is established around the solenoid coil 63 and resistor 61 and no appreciable amount of current will pass through said solenoid coil and resistor, as in the form of our invention illustrated in Figure 1.

As soon, however, as the circuit across the arcing

contacts

12 and 13 is broken by Warping of the bimetal resistor arms 15 and 16, the solenoid coil 63 will be energized. This will also operate the relay 66 and move the switch arm 64 thereof out of engagement with the stationary contact 65 into engagement with the stationary contact 69. The solenoid coil 63 will then be maintained energized through the switch arm 64, stationary contact 69, resistor coil 62, conductor 70 and warp switch 64 Upon ignition of the burner, the solenoid coil 63 is held energized through the switch arm 64 and stationary contact 69 and a conductor 71 connected with the hot contact 35 of the flame detector switch 30. When the flame detector switch is in its hot position the heater coil 62 is shorted out of the energizing circuit.

In this form of our invention like the form of our. invention illustrated in Figure 1, the solenoid 63 for the-v burner valve 20 is energized in series through the warp switch 60 and the cold contact 29 and is maintained energized through the hot contact 35 of the flame detector switch 30 when the gas issuing from the burner 11 has ignited. The solenoid 63 also is in series with the resistor 61 for the time delay warp switch 60 as the burner valve is initially open, and is in series with the resistor 62 upon opening of the burner valve and conditioning of the circuit for ignition of the burner, and remains in series with this resistor until ignition of the burner and the generation of sufiicient heat to engage the switch arm 31 with the stationary contact 35. A protecting circuit is thus maintained, which assures the shutting off of the gas supply should the burner fail to ignite, or if the gas sup ply should be turned oil, or if the circuit should be deenergized and then be turned back on again.

While we have herein shown and described several" forms in which our invention may be carried out, it will be understood that various modifications and variations thereof may be effected without departing from the spirit and scope of the novel concepts of the invention.

We claim as our invention:

1. In a safety gas burner ignition system including a gas burner, a gas burner valve on the supply side of said burner, a solenoid energizable to open said valve, an energizing circuit for said solenoid, and a parallel energizing. circuit having two normally engaged arcing contacts in the gas stream through said gas burner, bimetal means for separating said contacts, to effect an are, said contacts being connected across the energizing circuit and shorting. said solenoid out of the energizing circuit when in their normally engaged position and separating by heating said bimetal means by the heat of the short circuit to efiect an arc and effect the energization of said solenoid to open said burner valve.

2. In a safety gas burner ignition system including a gas burner, a gas burner valve on the supply side of said burner, a solenoid energizable to open said valve, a solenoid energizing circuit, a parallel igniter energizing circuit having at least one bimetal resistor arm connected therein and two normally engaged arcing contacts, one being carried by said resistor arm, said contacts separating upon warping of said bimetal resistor arm by resistor heat to effect an arc, said arcing contacts shorting said solenoid out of the energizing circuit when in their normally engaged position and separating to eifect an arc and the energization of said solenoid to open said burner valve, upon the energization of said bimetal resistor'arm to heat and warp the same.

3. In a safety gas burner ignition system including a; gas burner, a gas valve on the supply side of said burner,

a solenoid for opening said valve, a solenoid energizing:

circuit, a parallel igniter energizing circuit having two normally engaging arcing contacts therein, maintaining said solenoid energizing circuit deenergized when said contacts are engaged and opening by resistor heat created in said igniter energizing circuit to effect an arc and the energization of said solenoid energizing circuit, and a relay having a switch arm and a stationary contact and operating upon energization of said solenoid energizing circuit to engage said switch arm with said stationary contact and hold said solenoid energized as long as the burner is ignited.

4. In a safety gas burner ignition system including a gas burner, a gas valve on the supply side of said burner, a solenoid for opening said valve, a solenoid energizing circuit, a parallel igniter energizing circuit having two normally engaging arcing contacts therein connected.

across said energizing circuit, maintaining said solenoid energizing circuit deenergized when said contacts are enarranged to operate upon energization of said solenoid energizingfcircuit to-engage said switch armlwithi said stationary conta'ct and holdsaid solenoid'energized as lohg-as the burner is ignited, a 1 time: delay switch" opening-"both' of said energizing circuit means'in said solenoid energizingcircuit or operating said time delay switch, after a' predetermined time delay interval should the burner fail to ignite, and a flame detecting switch movable by the heat of the burner flame into position to hold solenoid energized and by-passing said means for operating said tim e delay switches-long as the burner is ignited.

'5.- In a safety gas burner ignition system including a gas burner, a gas valve on the supply side of said burner, a solenoid for opening said valve,"a solenoid energizing circuit, a parallel igniter'ener'gizing circuit having two normally'engaged arcing-contacts and a bimetal resistor for-each of said :ar'cing'contacts and arranged to separate said arcingcontacts by resistor-heat, said arcing contacts maintaining said solenoid energizing circuit deenergized when e'ngaged,and a rela'y' having a movable switch arm and a stationarycontact in said solenoid energizing circuit and moving said switch arm upon energization of said solenoid energizing circuitfeltected by the separation of said arcing contacts, to engage said stationary contact and hold said solenoid energizing circuit energized.

6'. In a safetygas burner ignition system including a gas burner, a gas valve on the supply side ofsaid burner, a solenoid for opening said valve when energized, a solenoid energizing circuit, a parallel igniter energizing circuit having two normally engaged arcing contacts therein maintaining said solenoidenergizing circuit deenergized when engaged, two bimetal resistor arms in said igniter energizing circuit, each having an arcing contact thereon and separating said' contacts by resistor heat to effect an arc and the energization of said solenoid energizing circuit, a flame detector switch having a first contact in said igniter energizing circuit and having a second contact connected with said solenoid energizing circuit, and a switch arm movable from'a' position in engagement with said first contact into engagement with said second contact by the heat generated by the burner flame for holding said solenoid energizing circuit energized.

7. In a safety gas burner'ignition system including a gas burner, a gas valve on the supply side of said burner, a; solenoid for opening said valve when energized, a solenoid energizing circuit, a parallel energizing circuit having two normally engaged arcing contacts therein maintaining said solenoid energizing circuit deenergized when engaged, two bimetal resistor arms in said igniter energizing circuit, each having an arcing contact thereon and separating said contacts by resistor heat to effect an arc and the 'energization of said solenoid energizing circuit, a flamedetcctor switch having a contact in said igniter energizing circuit and having a second contact in said second solenoid energizing circuit, and a movable switch'armmovable from a position in engagement with said first contact into engagement with said second contact by the heat generated by the burner flame for holding said solenoid energizing circuit energized, a time delay warp switch opening both of said energizing circuits after apredetermined time delay interval upon failure of said burner to 'ignite, and having a heater coil in said solenoid energizing circuit connectedin series with'said solenoid and a bimetal switch arm opening by the heat of said heater coil to deenergize both of said circuits should the burner fail to ignite.

8. in a safety'gas burner ignition system including a gas burner, a gas valve on the supply side of said burner, a'solenoid for opening said valve when energized, a solenoid ehergizing'circuit, a parallel igniter energizing circuit including two bimetal resistor arms each having an areing contact thereon, said contacts being normally engaged and separating ,by resistorheat to effectan arc and theqenergization of, said solenoid energizing circuit,

sess? a flame detector switch having a first contact on said igniterenergizing circuit and having a second contact- 3- connected in said' solenoid energizing circuit and a switch. armirnovable from a position in;engagenientwithsaidx first contact into engagement with said second contact; by the heat generated by the burner flame 'for holding said solenoid energizing circuit energized, a time delays warp switch openingboth said energizing circuits after a: predetermined time delayv interval upon.'failure of said burner to ignite and having a heater coil in said solenoid energizing circuit connected in series Withsaid solenoid and a bimetal switch arm opening by the heat of said heater coil to decnergize said circuits should the burner;

fail to ignite, and a relay having a movable switch; arm

connecting said heater coil with said first contact ofsaid;

flame detector switch and movable tofldisconnectjsaidzz heater coil and solenoid-from said first contact of Isaid flame detector switch, and connect said solenoid' and, heater coil in the energizing circuit independently oftsaid flame detector switch upon energization ofsaid solenoid,,;' said heater coil opening said warp switch after a predetermined time delay interval to deenergize both said enera.

gizing circuits, upon failure of the burner to ignite.v

9. in a safety gas burner ignition system including a when engaged, two bimetal resistor arms in saidigniter energizing circuit, each having an arcing contact thereon and separating said contacts by resistor heat toeflect an i are and the energization of said solenoid energizinggcirs cuit, a flame detector switch having a first contact insaid; igniter energizing circuit, a second contact in saidisolenoid.

energizing circuit and a switch arm movable from aspqsi tion in engagement with said first contact ,into engage:

ment with said second contact by the heat generated-by.-v

the burner flame, and a relay operable upon energization of said solenoid energizing circuit and having first and, second switch arms said solenoid energizing ,c1rcu1t,i. means for moving the first switch arm to connect said solenoid energizing circuit to be energized ,throughsaid second contact of said flame detector switch upon ignition,

of the burner, and means for moving thesecond switch arm to disconnect said solenoid and'heater coil from said first contact of said flame detector switch and connect said solenoid and heater coil directly in the energize ing circuit and by-passing said first contact of said flame:

detector switch, to hold said solenoid energized for; a predetermined time delay burner.

interval sufiicientto ignite said 10. in a safety ignition system including a gas burner,

a gas valve on the supply side of said burner a solenoid energizing circuit, a solenoid in saidsolenoid energizing,

circuit operable to open said valve when energized,;a'j parallel igniterenergizing circuit having two normally;

engaged arcing contacts therein and at least onejbiyj metal resistor having one of said arcing contacts thereon.

and warping to separate said arcing contacts by; resistor heat, said arcing contacts substantially shorting out s aid,

solenoid energizing circuit, when engaged, a relay having a movable switch arm connected in said solenoid ener:

gizing circuit and having first and second stationary contacts, the first stationary contact connecting said'sole-q noid energizing circuitwith said paralleligniter'enen, gizing circuit to effect the shorting 'out of vsaid solenoid energizing circuit when said arcing contacts are, engaged',:.-

a time delay warp switch for deenergizing both of :said

energizing circuits after predetermined time delay in tervals upon failure of the burner to ignite, said. first stationary contact of said relay having a.heater;coil-.r connected thereto and to said parallel igniter energizing circuit for initially supplying heat to open said ,warpi; switch, and said second stationary;-,contact of saidrelay;

having a heater connected thereto for supplying heat to open said warp switch upon operation of said relay to engage said switch arm with said second stationary contact.

11. In a safety gas burner ignition system including a gas burner, a gas valve on the supply side of said burner, a solenoid for opening said valve, a solenoid energizing circuit, a parallel igniter energizing circuit having two normally engaged arcing contacts and a bimetal resistor for each of said arcing contacts and separating said arcing contacts by resistor heat, a flame detector switch having a cold and a hot contact and a movable switch arm movable from a position in engagement with said cold contact into engagement with said hot contact by the heat of the burner flame, and a time delay warp switch, said parallel igniter energizing circuit including said bimetal resistors, said arcing contacts, the cold contact of said flame detector switch and said warp switch, a relay operated upon energization of said solenoid energizing circuit and having a movable switch arm in said solenoid energizing circuit and first and second stationary contacts engaged thereby, a heater coil for said Warp switch connected between said first stationary contact and with said parallel igniter energizing circuit, a heater coil connected witl: said second stationary contact and by-passing said first heater coil upon energization of said solenoid and movement of said switch arm into engagement with said second stationary contact, to eflect opening of said warp switch upon failure of the burner to ignite, and a conductor connected from said second stationary contact to said hot contact of said flame detector switch and by-passing said second igniter coil and holding said solenoid energizing circuit and solenoid energized through said second stationary contact of said relay as long as the burner is ignited.

References Cited in the file of this patent UNITED STATES PATENTS 346,430 Cutten July 27, 1886 761,379 Heany May 31, 1904 1,189,994 Obermeyer July 4, 1916 2,076,418 Smith Apr. 6, 1937 2,275,279 Beam Mar. 3, 1942 2,380,640 Eskin July 31, 1945 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2 ,869 ,633 January 20, 1959 Willard Arthur Schaaf Gt a1.

It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 10, line 10, for "igniter" read heater e Signed and sealed this 9th day of June 1959.

(SEAL) Attest:

KARL H, AXLINE ROBERT C. WATSON Attesting Oflicer Commissioner of Patents