US2593518A - Electrical fuel burner control system and apparatus therefor - Google Patents

Description

F- B. AUBERT April 22, 1952 Filed July 11, 1947 3 Sheets-Sheet 1 3 ATTORNEY aw i o R. 0 a m 2 l m w m U mm mm W. d \m 3 L VE vm p? M .QF Ow 1v V. B m@\e| 3 mm 2 5 h 5 2 m 4 2 E F 9 m WM U WN 4 fig d 3 r m @N A Y mm #5 om m9 g .Q Q 5m 0m cm A I" N\ E M BMM 8 Q em mm Mm F. B. AUBERT April 22, 1952 ELECTRICAL FUEL BURNER CONTROL SYSTEM AND APPARATUS THEREFOR 3 Sheets-Sheet 2 Filed July 11, 1947 wmu INVENTOR.

ATTORNEY F. B. AUBERT April 22, 1952 ELECTRICAL FUEL BURNER CONTROL SYSTEM AND APPARATUS THEREFOR 3 Sheets-Sheet 3 Filed July 11, 1947 INVENTOR.

BY W K M) ATTORNEY Patented Apr. 22, 1952 UNITED STATES PATENT OFFICE ELECTRICAL FUEL BURNER CONTROL SYSTEM ANDAPPARATUS THEREFOR 17 Claims. 1

This invention relates .to new and useful improvements in electrical fuel burner control systems and apparatus therefor.

An object of this invention is to provide a control system for fluid fuel burners having electrically operable fuel supply means and electrically controllable ignition means.

Another object of this invention is to provide a control system havin a means responsive to the occurrence of flame in the burner whereby the ignition means may he de-energized and enere gization of the fuel supply means continued.

Another object of this invention is to provide a safety means for a control system to de-energize the fuel supply means and ignition means upon failure of flame to occur in the burner within a predetermined time after initial energization of the system.

Another object is to provide a control device for automatically supervising the operation .of a fluid fuel burner.

Other objects of thisinvention will become apparent from time to time through the specification and claims as hereinafter stated.

This invention consists in the new and improved combination of parts and in their operative relationship to each other and in certain control devices therefor, all to be more fully described hereinafter and the novelty of which Will be particularly pointed outand distinctly claimed.

In the accompanying drawings to be taken as part of the specification there are clearly and fully illustrated several preferred embodiments of this invention in which drawings;

Figure 1 is -a diagrammatic representation of a fuel burner control system utilizing a thermostatic stack switch responsive to the occurrence of flame in the burner and operable tocontrol operation of the fuel supply meansgandtheignition means,

Fig. 2 is a diagrammatic'view of another form of burner controlsystem in which a photo-electric cell is positioned to be responsive to the occurrence of flame inthe burner and is operable. to control the activation of an electron tubein the system for controlling the ,fuel-supplymeans and ignition means for the burner and having electric timing means to delay functioningof the photoelectric cell'until-"the electron tube has had time to .become adequately heated,

Fig. 3 is adetail view, of the electric timing means portion of Fig. 2 in a partially operated position,

Fig. 4 is a detail .view of the electric timing means portion of Fig. 2 when the control system is in a fully operated position,

Fig. 5 is a detail view of the electric timing means portion of Fig.2 in safety operation,

Fig. 6 is a diagrammatic view of another form of a burner control system having 'a photoelectric cell and electron tube for controlling the operation of a fuel supply means and ignition means for the burner, having electric timing means to prevent functioning of the systemuntil the electron tube has had time tobecome adequately heated, and having safety means to deenergize the system and prevent further operation upon failure of flame to occur in the burner within a pre-determined time after initial ener gization of the system and having a safety stop member to prevent the safety means from returning to its initial position after operation,

Fig. '7 is a detail view of a section of the system shown in Fig. 6 including the safety means and is shown in an intermediate position of operation,

Fig. 8 is a detail view similar to Fig. 7 but shows the control system in fully operated position, and

Fig. 9 is another detail view similar to Figs. 7 and 8 showing the safety means in safety operatedv position.

Referring to the drawings by characters of reference, in the system shown in Fig. 1 there is a burner I having a fan or blower 2 and a fuel supply line 2 terminating in a nozzle. In the line 2 there is a pump l which is driven -by-a motor 3 which also drives the blower 2. Adjacent the nozzle there are ignition electrodes 4.

Electrical power from a main power source is supplied to electrical conductors 5 and 6 for energization of the system. The electrical conductors 5 and 6 are shown as leading to a connection or terminal board or panel I and connected-thereto by screws 8 and 9. The parts of the system are shown as beinginterconnected through the'connection panel 1. The elements of the'controlsystem to the right of the panel I in the drawing are sointerconnected and interrelated-in their operatlon that in commercial construction they-would probably be housed within a casing as an individual control device, the vconnections to the control device beingmade through the connection panel 1 as shown. From the connection points 8 and 9 on the panel 1, two electrical conductors i0 and H run to the primary ['2 of a transformer [Sand form a complete circuit therewith. From the secondary ['4 of the transformer l3 .a conductor l5 runs to a connection point 16 on the panel 1 from which another conductor I! leads to the fixed contact 18 of a room thermostator other control 3 switch I9. The thermostat I9 has a movable contact 29 carried by a thermo-sensitive bimetal strip or blade 2I which is connected by a conductor 22 to a connection point 23 on the panel 1. The thermostat I9 has a compensating, heater coil 24 which is connected by a conductor 25 from the blade 2| to a connection point 23 on the connection panel I. A conductor 21 leads from the connection point 23 to the coil 28 of a relay switch 29. The relay switch 29 has two fixed contacts 39 and BI and two movable contacts 32 and 33 cooperable respectively therewith and carried by pivoted contact arms 34 and 35 respectively, the switch contacts being held in open position initially by a spring 35. In the initial open position of the relay switch 29, the end portion 31 of the contact arm 35 engages and holds closed through an insulating abutment the pivoted contact-carrying arm 38 of a control switch 39. The control switch 39 has two fixed contacts 49 and M and has two movable contacts 42 and 43 cooperable respectively therewith and carried by the arm 38. A spring 44 is connected to the contact arm 38 urging it towards contact open position, the opening movement of the switch 39 being limited by the engagement of the arm 39 with a stop 45. The contact arm 39 has an electric insulating abutment 4B thereon which is engaged by a pivoted member 41 which is operable to continue to hold the switch 39 closed after releasing movement of the relay switch 29. The pivoted member 41 is urged towards its initial position in engagement with the abutment 45 by a spring 48 and is limited in its movement in this direction by a stop member 49. The upper portion 59 of the pivoted member 41 is engageable with the contact-carrying arm 5! of a switch 52, the contactcarrying arm 5I being of cantilever spring construction and tensioned toward contact closed position. The contact-carrying arm 5| carries the movable contact 53 which is initially in engagement with a fixed contact 54 of the switch 52. The arm 5I also carries a magnet armature 55 which is attracted by a permanent magnet 55 adjacent the fixed contact 54 which is operable to hold the contacts 53 and 54 tensioned against each other so that movement of the switch 52 will be with a snap action. A second relay switch 51 has a coil 58, a fixed contact 59 and a movable contact 69. The movable contact 59 of the relay switch 51 is carried by a contact-carrying arm BI and is urged towards open position by a spring 62. The contact-carrying arm 9I has an electric insulating abutment member 63 thereon which is engageable with the pivoted member 41 and operable to move the same out of holding engagement with abutment 49 upon closingv movement of the relay switch 51. A bimetal element 34 having an abutment member 65 of electric insulating material is engageable with and operable to move the pivoted member 41 off the abutment 49, the bimetal element 64 being energized for movement by an electric heating coil 95. The bimetal element 64 is also engageable with a flexible" stop member 61 which is'operable after heating and movement of the bimetal element 94 to prevent the same from returning to its initial position upon cooling. 'A reset member 68 having movement substantially longitudinal of the stop member 61 has a portion 69 operable upon movement to engage the stop member 61 to move or depress the same to permit the bimetal element 64 to return to its initial position. The reset member 68 also has a projecting portion 19 which is operable upon movement to engage and move the panel 1.

pivoted member 41 off the abutment 46 and open switch 52. A conductor 1I connects the coil 28 of the relay switch 29 with the contact arm 34 from which a conductor 12 runs to the fixed contact 54 of the switch 52. A conductor 13 leads from the movable contact 53 of the switch 52 to the connection point 14 on a conductor 15 completing a circuit to the secondary I4 of the transformer I3. A resistor 19 connects the connection point 25 on the panel 1 with a connection point 11 on the conductor 13. A resistor 13 and conductor 19 interconnect the fixed contact 39 of the relay switch 29 and a connection point 89 on the conductor 13 and function to complete a holding circuit for the relay switch 29 when the contacts 39 and 32 are closed. From the other fixed contact 3I of the relay switch 29 a conductor 8I leads to a contact point 92 on the conductor II. A conductor 33 leads from the relay contact arm 35 to the fixed contact 59 of the second relay switch 51. Another conductor 94 interconnects a connection point 85 on the conductor 83 and the contact arm 38 of the control switch 39. A conductor 86 leads from the fixed contact 4| of the switch 39 to a connection point 81 on the panel I, the circuit being completed by conductors 89 and 89 through the motor 3 to the ground conductor 5. The pivoted arm 9! of the second relay switch 51 is connected by a conductor 99 to the connection point 9! on the conductor 86. A conductor 92 runs from the fixed contact 49 of the switch 39 to a connection point 93 on the panel I, the circuit being completed by conductors 94 and 95 through the primary 96 of an ignition coil 91 to the ground conductor 5. A conductor 98 leads from a connection point 99 at the fixed contact 49 to the heater coil 63 of the bimetal element 34 which is in turn connected by a conductor I99 to a connection point IIlI on the ground conductor I0 from the transformer I2. A conductor I92 leads from the coil 59 of the relay switch 51 to a connection point I93 on the Another conductor I94 runs from the panel point I93 to the-fixed contact105 of a thermostatic stack switch I93. The thermostatic stack switch I95 has a movable contact 191 ccoperable with contact I95, the movable contact I91 being actuated by a thermostatic bimetal element I99 responsive to stack temperature. The circuit through the stack switch I06 is completed by a conductor I99 running from the movable contact I91 to a connection point I I9 on the conductor I1 to the thermostat I9. It should be noted that in this form of the invention as illustrated in the drawing in Fig. 1 the system is shown in its normal starting position prior to energization.

In operation, this iorm of the invention functions as follows:

When electric current is supplied through the conductors 5, 6, I9 and I I to the primary I2 of the transformer I3 the system is energized subjectto control of the various switches and control mechanisms therein. The initial circuit for the thermostat I9 runs from the transformer secondary I4 through the conductors I5 and I1 to the fixed contact of the thermostat. Assuming that when this system is initially energized the space to be heated will be cold, the contact points I8 and 20 of the thermostat I9 will be closed completing the circuit through the conductors 22 and 21 to the relay coil 28 and thence by conductors 1| and 12 to the closed contacts 53 and 54 of the switch 52, returning by the conductors 13 and 15 to the transformer secondary I4. With this circuitclo'sed through'the thermostat I9, the coil 28 of the relay 29 is energized and will cause the contacts 32 and 33to close against the fixed contacts' 39 and 3|. The closing of the contact 32 against the contact 30 completes a circuit from therelaycoil 28 through the closed contacts 32,

and 30, the resistor 18, conductor 19 and conductors 13 and 15 to the transformer secondary I4. This last-named circuit is a holding circuit for the relay switch 29 and will hold the same closed so long as the transformer I3 remains energized and-the thermostat remains closed. The resistor 18 functions as a drop out resistor so that if the voltage supplied to the coil 28 should drop below a predetermined minimum value the voltage drop through the resistor 18 would be so great that there would not be sufiicien't current through the coil 28 to hold the switch 29closed. The conductor' 8I leads from the connection point 82 on the-hot conductor II to the contact 3| of the relay switch 29 and when the relay switch 29 is closed a circuit is completed through the contact arm-35 and the conductors 83 and 84 to the control switch 39. The control switch 39 functionsto control the energizationof the circuits through the motor 3 and the ignition coil 96 respectively by control of the contact points 43 and 42 respectively. It is seen then that when the system is initially energized the thermostat I9 closes causing'therelay'switch 29 to close establishing a holding circuit therethrough and energizing a circuit through the'motor 3 through the switch contacts 4| and 43 and the conductors 86, 8'8 and 89, and a, circuit through the ignition coil through the contacts 42 and 40 and conductors 92, 94 and 95. At the same time that the circuit through the ignition coil 96 is energized a branch circuit is completed through the conductor 98 to the heater coil 66 for the bimetal 64 and a conductor I98 leading to ground. If the system is functioning properly when the motor and ignition are energized there will be combustion and immediate occurrence of flame in the burner I. The occurrence of flame in the burner I will cause the thermostatic switch I96 to be heated thereby closing the contacts I05 and I01 and completing a circuit from the transformer secondary I4 through the conductors I5, I1, I99, I04, and I92 to the coil 58 of the second relay switch 51, which circuit is completed back to the transformer secondary by the conductor 15. The energization of the last-named circuit through therelay coil 58 will cause the switch contact 69 to close and by movement of the contact arm BI and'abutment 63 'willmove the pivoted member 41 clear of the abutment 46 thereby permitting the switch 39 to open, because the contact arm 35 of the relay switch 29 in closing moved free of engagement with the contact arm 38 of the switch 39 thus leaving the pivoted member 41 in primary control of the switch 39. The opening of the switch 39, by opening the contacts 42 and 43, causes the circuit through the motor 3 and the ignition coil 96 to be. de-energized, but the closing of the contacts 69 and 59 of'the second relay switch 51 establishes substantially simultaneously a second motor circuit (this second motor circuit running by conductor 8| to the closed contacts 3I and 33 of the relay switch 29, by the contact arm 35, the conductor '83, closed contacts 59 and 69 of the second relay switch 51, and the conductors 99, 86, 8B and 89 through the motor 3 to the ground wire 5, this second motor circuit by-passing the open switch39). It shouldbe noted that the movement-or the pivoted member 41 which permits switch 39'to open also opens switch 52. However, the opening of switch 52 at this point of operation does not affect the operation of the relay coil 28 which remains energized through the previously described holding circuit which includes relay switch contacts 30 and 32.

It is seen that in normal operation of this system the motor and ignition are'initially energized but upon recognition of flame by the stack switch 196, the relay switch 51 closes causing the switch 39 to open thereby de-energizing the motor and ignition circuits and energizing a second motor circuit for the maintenance of fuel for the operation of the burner.

If the contacts I and I01 of the stack switch 506 fail to close for any reason (e. g., a failure of flame in the burner) or if the second relay switch 51 should fail to function for any reason, the heating of the bimetal element 64 by the heating coil 66 will cause the abutment 65 to engage and move the pivoted member 41 off the abutment 46 and thus permit the switch 39 toopen to de-energize the motor and ignition circuits, the switch 52 being opened simultaneously by movement of the pivoted member 41. This actionof the bimetal element 64 is a safety feature of this system to prevent the supplying of fuel to the burner I if there is a failure of ignition in the burner or a failure of the flame recognition circuit. When the bimetal element 64 moves to its safety operated position it moves past the end of the flexible stop member 61 which slips into position behind the bimetal element 64 thereby preventing the same from returning to its initial position upon cooling. This last-named safety action causes the pivoted member 41 to hold open the switch 52 and thus functions to prevent immediate re-energization of the circuit by opening and subsequently closing the thermostat I9 until investigation has been made to attempt to determine why there has been a failure of the system to function. (Without this last-named safety feature, if the flame recognition circuit failed to function for any reason and the system was moved to safety position as heretofore described, the circuit could be re-established by opening and closin of the thermostat I9 whereupon the system would again begin its cycle of operation as heretofore described, continued cycling of fuel in this manner without ignition thereof would cause a dangerous flooding of the burner.) To reestablish the system after safety operation of the bimetal element 64, the thermostat I9 should be opened to tie-energize the holding circuit through the coil 28 of the relay switch 29 to permit the same to ope This opening of the relay switch 29 will cause the pivot arm portion 31 to engage the contact arm 38' and close the control switch 39.

The reset member 93 should then be pushed in so that'thearm 69 will engage the flexible stop member 61 to move the same downward to permit the bimetalelement 64 to return to its initial position andupon release of the reset member 69 the pivoted member 41 can return to its initial position, The arm 10 permitting the switch 52 to close. of the reset member 68 is operable upon movement to engage and move the pivoted member 41, this last-named action being an additional safety feature of the system so that the reset member 68 may not be held in actuated position so that the re-starting of the system after safety operation can be controlled from the thermostat alone. If the arm 19 was not employed and the reset member 68 were permanently in actuated position,-the flexiblestop member -61 would-never function and the bimetal element 64 would always return to its initial position upon cooling and the system could be re-started by opening and closing of the thermostat I9. The arm of the reset member 66 by its engagement and movement of the pivoted member 41. is operable to hold open the switch 52 and thus break the initial circuit for the relay coil 29 of the first relay switch 29.

In the form of the invention illustrated in Fig.

'2 there is a burner III having an air and fuel supply means I I2 driven by an electric motor H3 and having an electric spark ignition 5 I4. There is a main electric power source H5 leading to a main line switch II6 from which conductors H1 and H8 lead to connection points I I9 and I respectively on a connection panel I2I. As in the previous form-of the invention described the various electric circuits are shown connected through the connection panel I2I and in commercial construction the connection panel and all elements of the system to the right thereof on the drawing would be enclosed in a casing or housing as a control device for the system.

From the control panel I2I two conductors I22 and I23 lead to the primary I24 of a transformer I25. There are three secondary portions, I26, I21 and I28, for the transformer I25 from which run the various controlling circuits for the system. There is a thermostat I29 which'is responsive to the heat output of the burner III and is operable to control energization of the system. The thermostat I29 has a fixed contact I30 and a movable contact I'3I which is carried by a bimetal element I32. The thermostat I29 has a compensating resistor I33 connected in a shunt circuit from the bimetal element I32 which is operable to reduce hunting by the thermostat I29. There is a relay switch I34 having a coil I35 which is controlled by the thermostat I29 for controlling the system. The relay switch I34 has three pairs of contacts carried by two contactcarrying arms I56 and I31 and is held by a spring I39 so that two pairs of its contacts I39, I40 and MI, I42 are initially open and one pair of its contacts I43 and I44 are initially closed. An end portion I45 of the contact arm I36 having an insulating abutment engages and holds closed the contact arm I46 of a control switch I41 which is urged towards open position by a spring I48 and has its opening movement limited by a stop member I49. The contact arm I46 has a nonmetallic abutment portion I50 thereon against which is positioned a pivoted member I5I which is operable to control the operation of the switch I41 after the contact arm portion I45 of the relay switch I34 has moved away from engagement with the contact arm I46. The pivoted member I5I is urged towards its position of engagement with the abutment I56 by a spring I52 and is limited in its direction of movement by a stop member I53. The upper portion I54 of the pivoted member I5I is operable upon movement to engage and move the contact carrying arm I55 of a single pole double throw type switch I56 which has one pair of contacts I51 and I59 initially closed, and a second pair of contacts I59 and I60 initially open. The contact-carrying arm I55 of the switch I56 has positioned thereon a magnetic armature I6I which is cooperable with a permanent magnet I62 adjacent the contact I58 and which is operable to cause the switch I56 to move with a snap action. The contactcarrying arm I55 is of a cantilever construction, the contact I51 and I58 being urged by the spring 'force of the arm I55 towards an initially closed position. There is a second relay switch I63 having a coil I64 and a fixed contact I65 and movable contact I66. The movable contact I66 is carried by the pivoted contact-carrrying arm I61 and is urged towards open position by a spring I68. The contact-carrying arm I61 of the relay switch I63 has an insulating material abutment portion I69 thereon which is cooperable with the pivoted member I5I to cause movement thereof upon closing movement of the relay switch I63. A bimetal element I10 having an insulating material abutment portion HI and heating coil I12 therefor is cooperable with the pivoted member I5I upon heating and is operable to cause movement thereof. An electron tube I13 is connected in circuit with the relay switch I63 and is operable to control the same. The electron tube I13 is of a type having a control grid I14 which is controlled by a photo-electric cell I15 in circuit therewith. From the secondary portion I26 of the transformer I25 there is a conductor I16 leading to a reset switch I11 which is held by a spring I18 in a normally closed position. A conductor I19 leads from the reset switch I11 to a connection point I on the panel I2I from which another conductor I6I leads to the fixed contact I30 of the thermostat I29. A conductor I82 connects the bimetal element I32 of the thermostat I29 with the connection point I83 on the panel I2I which is connected by a conductor I84 to the coil I35 of the relay switch I34. The coil I35 of the relay I34 is connected toa conductor I85 which interconnects the fixed contact I42 of the relay switch I34 and the fixed contact I58 of the switch I56, there being a resistor I86 in series with the conductor I81 runs from the contact arm I55 of with the coil I35 and the fixed contact I42. The conductor I81 runs from the contact arm I55 of the switch I56 to a connection point I88 on a conductor I89 which interconnects the contact arm I31 of the relay switch I34 and the connection point I90 on the secondary portion I26 of the transformer I25. The compensating resistor I33 on the thermostat I29 is connected by a conductor I91 to aconnection point I92 on the panel I2I which is in turn connected by a resistor I93 to a connection point I94 on the conductor I81. The electron tube I13 has a cathode I95 which is heated by a cathode heater element I96. The cathode heater element I96 is energized by a circuit from the secondary portion I21 of the transe former I25 through conductors I91, I98 and I99. The secondary portions I21 and I28 are connected at'a connection point 200 to which is connected the conductor I98. From a connection point 20I on the conductor I98 a conductor 202 connects with the connection point I90 on the secondary portion I26 thus providing an operative interconnection of the three transformer secondary portions. The electron tube I13 has a shield grid 203 which is connected by conductors 204 and 205 and by a resistor 206 and capacitance 201 to ground at 206. The cathode heater coil I96 is connected to the shield grid 203 by conductors I99, 299, 205 and 204. The control grid I14 of the electron tube is connected by conductor 2I0 and a resistor 2 to the cathode 2I2 of the photo-electric cell I15. The photo-electric cell I15 has an anode 2I3 which is connected to ground at 2I4 by a conductor 2I5. The photoelectric cell I15 is housed in and surrounded by a casing or shield I15 which admits light only from the burner flame so that the cell I15 is solely responsive thereto. The conductor 2I0 which connects the photo-electric cell I to the control grid I14 has a shield 2I6 therearround to prevent capacitance between the conductor 2H] and the system. The conductor 2I1 connects the shield 2I6 to ground to prevent capacitance between the shield 2I6 and the system. A capacitance 2I6 is positioned between the conductor 2I0 and the secondary portion I26 so that the current on the control grid I14'will be out of phase with the current on the plate or anode 2 I9 of the electron tube I14 to such an extent that a very slight change of current upon the control grid I14 will render the electron tube I13 conductive, the capacitance 2I8 also functions to determine the charge or negative bias on the control grid I14. There is a resistor 220 and conductor 22I runnin from the anode 2I9 of the electron tube I 13 to the coil I64 of the relay switch I63 and another conductor 222 leading from the coil I64 to the secondary portion I28 of the transformer I25. A capacitance 223 is positioned between connection point 224 on the conductor 222 and the conductor 22!. Another capacitance 225 is positioned between the conduc tor 264 and the conductor 22I. The'capacitors and resistors positioned in the circuit around the electron tube function to reduce capacitance within the tube and to prevent radio interference. A conductor 225 runs from the cathode I95 of the electron tube I13 to the contact I44 of the relay switch I34 from whence another conductor 226 runs to the fixed contact I60 of the switch I56. A conductor 221 runs from the hot conductor I23 to the fixed contact I 43 of the relay switch I34. The contact arm I36 of the relay switch I34 is connected by a conductor 221 to the fixed contact I55 of the relay switch I63 and is connected at a connection point 228 to the contact arm I46 of the control switch I41. The control switch I 41 has two fixed contacts 229 and 230 and two movable contacts 23I and 232 respectively cooperable therewith which are carried by the contact arm I46. A conductor 233 runs from the fixed contact 229 of the switch I41 to a conductor 234 which connects through a connection point 235 on the connection panel I 2I to the primary coil 236 of the ignition transformer 231 and thence by a conductor 238 to the ground conductor II1. From the junction point 239 of the conductors 233 and 234 a conductors24ii runs to the heater coil I12 for the bimetal element I10, another conductor 24I completing'the circuit from the heater coil I12 to the ground conductor I32. From the fixed contact 233 of the switch 541 a conductor 242 connectswith aconductor 243 leading to the connection point 26-4 on the connection panel I2I from whence a conductor 245 leads to the motor II 3 and a conductor 249 completes the circuit to, the ground conductor II'i'. From the junction point 241 of the conductors 242 and 243 a conductor 243 connects with the contact arm I61 of the relay switch I 53.

In this system the position and operative relationship of parts are as shown in Fig. 2 before the system is energized. When the main switch II6 is closed. the circuit through the conductors II 1, I I8, I22 and I23 is completed through the transformer primary I24 thus preparing the system for operation. With the transformer I25 energized, a circuit is energized for the heater coil I 96 of the. electron tube I13 and the tube I13 begins to heat in preparation for controlling the system. When the thermostat I29 closes calling for heat, a circuit is 'ompletedfrom the 10 transformer secondary portion I26 through the conductor I 16, the reset switch I11, the conductors I19 and I8I, the closed contacts I30 and I3I of the theromstat I29, the conductors I82 and I84, the relay coil I35, the conductor I85, the closed contacts I51 and I 58 of the switch I56, the conductor I81, and the conductor I89 leading to the transformer secondary portion I26 at the connection point I90. This last-named circuit energizes the coil I35 of the relay switch I34 causing the contacts I39 and MI to close against the fixed contacts I40 and I42 respectively and the contacts I43 and I44 to open. When the contacts MI and I42 of the relay switch I34 are closed, the circuit through the coil I35 is then completed through the resistor I86 and the closed contacts I 4!, I42 to the conductor I89 leading to the transformer secondary portion.I26. This last-named circuit is a holding circuit for the relay coil I35 which will be energized at all times that the main switch Iii-3 is closed and the thermostat I23 is closed. Before the relay switch I34 closes there is a circuit running from the cathode I of the electron tube I13 through the conductor 225 the closed contacts I43 and I44 of the relay switch I34, the conductors I89 and 202, the secondary portion I28, the conductor 222, the relay coil I 64, the conductor 22I and the resistor 220, the circuit being completed to the anode 2I9 of the electron tube I13. This lastnamed circuit is operative as a safety means, the operation of which will be described at a later time. With the contacts I39 and I40 of the relay switch I34 closed, there is a circuit established from the hot conductor I23 through the conductor 226, the closed contacts I39 and I40 and the contact arm I36, and the conductor 221 to the contact arm I46 of the control switch I41. At the control switch I41 the aforementioned circuit divides and a portion of the same is completed through the conductors 242, 243 and 245 to the motor II3, the circuit being completed to the ground conductor II 1 by conductor 246. This last-named circuit functions to energize the motor II 3. Another portion of the circuit from the switch I41 runs from the contacts 229 and 23I through a conductor 233 to the connection point 239 where the circuit divides, a portion of the circuit being completed through conductors 234 and 236 through the ignition coil 236 to the ground conductor II1, and another portion of the circuit runs through the conductor 240 to the heater coil I12 for the bimetal element I10 and is completed through the conductor 24I to the ground conductor I22. These last-mentioned circuits energize the ignition elec trodes H4 for the burner III and the heater coil I12 for the bimetal element I10 respectively. When the relay switch I34 is closed and the contacts I43 and I 44 are open the aforementioned circuit from the cathode I95 of the electron tube I13 through the coil I64 of the relay switch I63 is broken. As the heater coil I12 heats the bimetal element I10 this element moves the abutment I1I against the pivoted member I5I causing the same to move. After a predetermined period of heating by the heater coil I12 the bimetal element I10 will cause the abutment I1I to move the pivoted member I5! until the upper portion I54 engages and moves the contact arm I 55 of the switch I 56. Thismovement of the pivoted member I5I will cause the contact arm fuel to be ignited at the burner the system functions normally, the fuel is ignited 11 pivoted member I i required to close the contact I59 and I60 of the switch I66 is so determined that the pivoted member I5I will not have moved clear of the abutment I50 of the switch I41 at this time. This position of movement of the bimetal element I10, the pivoted member I5I and the contact arm I55 is illustrated in Fig. 3 wherein the bimetal element I has moved the aforementioned parts to the position described thus closing the contacts I59 and I60 and thereby establishing a second circuit from the cathode of the electron tube I13. This second cathode circuit is operative through the conductors 225 and-.226, the closed contacts I59 and I60 of the switch I56, the conductors I81, I89 and 202, the secondary portion I28, the conductor 222, the relay coil I64, the conductor 22I and the resistor 220, the circuit terminating at the anode 2 I9.

At this point in the operation of the system, with the thermostat I29 closed and the circuits to the ignition and to the motor through the switch I41 energized, the closing of the contacts I59 and I60 of the switch I56 establishes a second cathode circuit rendering the system responsive to the occurrence of flame at the burner III. With the motor and ignition circuits energized, the next step in the normal sequence of operation of the system would be for the III. If

at the burner III and the occurrence of flame will cause the photo-electric cell I to become energized and drain a negative potential from the control grid I14 of the electron tube I13 thus rendering the electron tube I13 conductive. When the electron tube I13 is thus rendered conductive by the occurrence of flame at the burner III current will be able to flow through the electron tube thus completing the second cathode circuit and energizing the relay coil I64.

' Fig; 4. When the switch I41 is opened by the aforementioned movement of the pivoted member I5I the opening of the switch contacts 229 and 23I, 230 and 232 will de-energize the circuits to the motor II3, the ignition transformer 236, and the heater coil I12, these elements having been described heretofore as being in circuit with the switch I41. The closing of the relay switch I63 simultaneously with the opening of the switch I41 causes the establishment of a second circuit for the motor from the hot conductor I23 through the conductor 226, the closed contacts I39 and I40, the contact arm I36, the conductor 221 the closed contacts I65 and I66 of the relay switch I63, the contact arm I61, the conductor 248, and the conductors 243, 245 and 246 through the motor II3 to the ground conductor II1.

It is seen then that in normal operation when the system is energized and the thermostat I29 calls for heat, the relay switch I34 closes establishing a holding circuit for itself and energizes circuits for the motor II3, the ignition H4 and the heater coil I12 through the switch I41. The heater coil I12 then functions as a timer for moving the contact arm I5I to close the switch contacts I59 and I60 to establish a second circuit from the cathode, the length of time for this 12 operation being substantially that required for the heating of the electron tube I13. The occurrence of flame then at the burner III causes the activation of the electron tube I13 and completes the circuit through the relay switch I63 causing the same to close and thus de-energizing the motor, ignition, and heater coil circuits and substantially simultaneously energizing a second motor circuit. If, for any reason, the relay switch I63 fails to close at the time when the heater coil I12 and the bimetal element I10 have moved the pivoted member I5I and contact arm I55 to establish the aforementioned second circuit from the cathode, the heater element I12 will continue to cause the bimetal element I10 to move the pivoted member I5I. If the relay switch I63 then fails to close before the pivoted member I5I moves clear of the abutment I50 the switch I41 will be opened thus deenergizing the motor, ignition, and heater coil circuits. This last-mentioned operation is as shown in Fig. 5 and functions as a safety for the system in the event that the relay switch I63 fails to close. (The failure of flame at the burner III or the failure of the electron tube I13 to function are the principal causes of such safety operation but the safety operation would function as described should the relay switch I63 fail to close for any reason whatsoever.) When the bimetal element I10 has cooled and returned to its initial position after'the safety operation, the pivoted member I5I will not be able to return to its initial position because of its engagement with the edge of the abutment I50 of the switch I41. After such safety operation the system will not be able to function again until the relay switch I34 is permitted to open (the relay switch I34 being held closed by its holding circuit during safety operation). If the circuit through the coil I35 of the relay switch I34 is opened, either by opening the thermostat I29 or by opening the reset switch I11, the holding circuit for the coil I35 will be broken thus permitting the spring I38 to move the switch I34 to its initial open position. This opening movement of the relay switch I34 will cause the end portion I45 of the contact arm I36 to engage the contact arm I46 of the switch I41 causing the same to be closed since the spring I38 is stronger than the spring I48. Upon this closing of the switch I41 by the relay switch I34 the spring I52 will then be able to move the pivoted member I5I back into engagement with the abutment I50. This last sequence of operation places the system in its initial operating condition and renders the same operative upon closing of the thermostat I29 and the operation of the other units of the sys tem as heretofore described. If, while the system is energized and in its initial or off position, as shown in Fig. 2, the conductor 2I0 from the control grid I14 should become shorted giving a continuous and false indication of flame at the burner III, the first-named circuit from the cathode I through the closed contacts I43 and I44 of the relay switch I34 will function as a safety means to protect the system. If the described condition occurs, the electron tube I13 will become conductive permitting a completed circuit through the relay coil I64 and causing the relay switch I63 to close. The closing of the relay switch I63 will cause the pivoted member I5I to be moved, as previously described, thus opening the switch I41 and the switch contacts I51 and I58 of the switch I56. The opening of the switch I 41 will protect the system in that "as a. unit control device. "two conductors 258 and 251 lead to connection points 258 and 258 respectively. From the conheat output of the burner 249.

with a fixed contact 29!.

Inthe system shown in Fig. 6 there is a modifi cation of the form shown and described in Fig. 2 with certain safety features added and modification of the circuits for the adaptation of these safety features.

"There is a burner 249 having a fuel and air supply'blower 258 driven by a motor 25! and having an electric spark ignition 252.

Electric power for the system is supplied from a main power source 253 and is controlled by a switch 254. As was described in the previous forms of "this invention the circuits are shown as being connectedithrough a connection panel 255 and in commercial construction all of the elements :shown to the right of the connection panel would be. assembled within a casing or other enclosure From the switch 254 nection points 258 and 259 the circuit is con pleted' through the primary 288 of a transformer 28! by. conductors 282 and 283. The transformer 26! has three secondary portions 264, 285 and 266'from which run the circuitsfor the energization of the system. A thermostat 281 is connected i 268, 269 and 218 and is operable to control the operation of the system by its response to the The thermostat 251 has a fixed contact 21! and a movable contact 212 carried by a bimetal element 213 from which is connected a resistor 214 which is operable to compensate the thermostat for irregular variations in temperature. The contacts 21! and 212 and the compensating resistor 214 are con- The thermostat 261 is energized by a circuit running from the "secondary portion 284 of the transformer 28! which is connected by a conductor 218 to a connection point 218 on the connection panel 255. From the connection point 288 on the connection panel 255 a conductor 219 runs to a relay coil 288 of a relay switch 28!. The relay switch 28! has two pivoted contact-carrying arms 282 and 283 which carry the movable contacts 284, 285 and 288, the contacts 284 and 285 being carried by the contact arm 282. The contacts 288 and 285' are engageable'with the fixed contacts 231 and'288 respectively, which are carried by flexible supporting members 289 and 298. The contact 288 carried by the'contact arm 283 is engageable The switch contacts 281 and 284 are initially closed and the contacts 285, 288, 286 and 29! are initially open, the switch'being held in this initial position by a spring 292. The flexible contact arm 289 is inherently flexed towards a stop member 293 towards which it will move upon closing movement of the switch 28!. The flexible contact arm 288 is likewise tensioned against the stop member 294. When the relay switch 28! is closed, the contact-carrying arms 282 and 283 move downward under the attraction of the relay coil 288 member 293 is so positioned that the contact 288 will" not "break away from the contact 281 until contact has been made between the'contacts 285 and 288'which movement continues until the. contacts 288 and 29! are closed andthe flexible contact arm 298 is tensioned away from the stop member 294. Upon opening movement. of the relay switch 28! a similar action takes place in that the contact 288 will not break from thecontact 29! until contact has been made between the contacts 284 and 281. The pivoted contact-carrying arm 282 of the relay switch 28! has an electrically insulated end portion 295 which is engageable with the contact carrying arm 2980f a switch 291 when the relay switch 28! is in its initial open position. The contact-carrying arm 298 is urged by a spring 298 towards an open position but is limited in this movement by a stop member 288.. The contact arm 296 carries two contacts 388 and 38! thereon which. are engageable with fixed contacts 382 and 383 respectively. The contact arm 299 has a non-metallic abutment member 384 thereon which is engageable by a pivoted member 385 which ls'operable to hold the switch 291 closed when the pivoted arm portion 295 of the relay switch 29! is not in engagement therewith. The pivoted member 385 is held in its position of engagement with the abutment member 385 by a spring 386 and is limited in this direction of movement by a stop member 381. The upper portion 388 of the pivoted member 385 is engageable with the contact carrying arm 389 of a switch 3!8. The switch 3!8 has a fixed contact 3!! and a movable con tact 3!2 carried by the contact arm 389, the contact arm 389 being ofa cantilever construction and urging the contacts 3! and 3!2 towards engagement, The contact arm 389 carries a magnetic armature 3!3 which is cooperable with a permanent magnet 3M adjacent the fixed contact 3i! and is operable to cause the switch 3!!! to open and to close with a snap action; A second relay switch 3i5 has two pivoted contact carrying arms 3l5 and 3!1, the pivoted contact arm 3!1 having an electrically insulated abutment portion 3!8 thereon which is operable upon movement to engage and move the pivoted memher 385. The relay switch 3!5 has a coil 3!!! which is operable on energization to move the contact arms 358 and 3! 1, the same being held in an open position by a spring 328. The relay switch 3!?! has two movable contacts 32! and 322 which are carried by the pivoted contact arms 3!5 and 3H respectively, and two fixed contacts 323 and 828 which are carried by two flexible supporting members 325 and 328. The relay switch 3!5 is operable upon closing movement to cause the abutment member 3! 8 to engage'and move the pivoted member 385 clear of the abutment 384 thus permitting the switch 291 to open and simultaneously by engagement of the upper portion 388 with the contact arm 389 to cause the switch'3l8 to open. The fixed contacts 323 and 324 of the relay switch 3l5 are so positioned in relation to the movable contacts 32! and 322 that when the relay switch 3!5 closes the contacts 322 and 324 will engage prior to the opening of the switch 3!!) and the relay switch M5 and will have an overtravel movement due to the flexibility of the flexible contact arms 325 bimetal element 321 has a flexible stop member 339 engageable therewith which is operable to prevent the same from returning to its initial position upon cooling after having performed its safety function. A reset member 33! has an arm portion 332 engageable with the flexible stop member 339 upon movement and is operable to move the same to permit the bimetal element 321 to return to its initial position upon cooling. The reset member 33! also has an arm portion 333 which is operable upon movement to engage and move the pivoted member 395 to open the switch 3!!) and to hold the same open so long as the reset member 33! is in its operated position. The reset member 33! also has a side arm or projecting portion 334 which is engageable upon movement with the operating arm 335 of a reset switch 333 and is operable to open and to hold open the same while .in operated position. In circuit between the switch 3H} and the relay switch 28! is an electric timing switch 331 which operates to delay the functioning of the relay switch 28! for a predetermined time. The timing switch 331 has a fixed contact 333 and a movable contact 339, the movable contact 339 being carried by a bimetal element 348. Through the switch 331 runs a resistor 34! which is operable to cause a sufiicient voltage drop therethrough to prevent operation of the relay switch 29! so long as the resistor 34! is functioning. The bimetal element 349 of the timing switch 331 is responsive to the heat generated by the resistor 34! and is operable after a predetermined period of heating to warp so that the contacts 338 and 339 will close and establish a shunt circuit through the bimetal element 349 which has a very low resistance compared to the resistor 34!. The relay switch 3!5 has an electron tube 342 in circuit therewith, said electron tube being operable to control energization of the relay coil 313. The electron tube 342 is of the controllable grid type having a control grid 343 which is controlled by a. photo-electric cell 344 which is responsive to the occurrence of flame at the burner 249. From the relay coil 28!] of the relay switch 28! there is a conductor 345 leading to the reset switch 338 which is in turn connected by a conductor 346 to the pivoted contact arm 282 of the relay switch 28!. From the flexible contact arm 289 of the relay switch 28! there is a conductor 341 leading to the timing switch 331 from whence a conductor 349 leads to the contact arm 399 of the switch 3H3. From the fixed contact 3!! of the switch 3|9 a conductor 349 runs to the contact arm 3H of the relay switch 3 !5. From a connection point 359 on the conductor 349 another conductor 35! leads to a connection point 352 on a conductor 353 which together with a drop-out" resistor 354 interconnects the flexible contact arm 299 of the relay switch 28! and a conductor 355 leading to the transformer secondary portion 264. The transformer secondary portions 265 and 256 are connected at connection point 356 and are together connected to the conductor 355 at a connection point 351 by which an operative interconnection of the three secondary portions is obtained. From the connection point 358 on the hot? conductor 252 a conductor 359 runs to the contact arm 283 of the relay switch 28!. From the fixed contact 29! of the relay switch 28! a conductor 369 runs to the contact arm 293 of the switch 291, a branch conductor 35! running from a connection point 362 of the conductor 333 to the flexible contact arm 325 of the relay switch 3!5. From the fixed contact 393 of the switch 291 the conductor 363 runs to the connection point 364 on the connection panel 255, from whence a conductor 365 runs to the motor 25! which is in turn connected by conductor 366 to the ground conductor 251. From the fixed contact 392 a conductor 361 runs to the connection point 368 on the connection panel 255 to which is connected-the primary 369 of the ignition transformer 319 which is in turn connected to the ground conductor 251 by a conductor 31!. A branch conductor 312 runs from the connection point 313 on the conductor 361 to the heater coil 328 of the bimetal element 321 from whence a conductor 314 runs to the ground conductor 263. The electron tube 342 has a cathode 315 which is heated by a cathode heater coil 316. The electron tube 342 has a screen grid 311 and an anode 918. The cathode heater coil 316 is connected by a conductor 319 to thetransformer secondary portion 265 and is connected to the conductor 355 at a connection point 399, the circuit from the conductor-355 being completed back to the transformer secondary portion 255 by a conductor 38! interconnecting the connection points 356 and 351 thus completing the cathode heater circuit. The circuit from the compensating resistor of the thermostat 251 is completed from the connection panel at point 299 by a conductor 382 having a resistor 383 therein to a connection point 384 on the conductor 355. From the cathode 315 of the electron tube 342 a conductor 385 runs to the flexible contact supporting member 326 of the relay switch 32' 5. A conductor 386 runs from a connection point 381 on the conductor 395 to the contact arm 399 of the switch 3H3. From the transformer secondary portion 266 a conductor 388 runs to a connection point 389 from whence another conductor 39!] runs to the coil 3!9 of the relay switch 3!5. From the coil 3!9 of the relay switch 3l5 the conductor 39! runs to a connection point 392 from whence a resistor 393 completes the connection to the anode 318 of the electron tube 342. A capacitance 394 is positioned between the connection point 395 on the conductor 39! and the connection point 389 at the juncture of the conductors 388 and 396. At the connection point 392 a capacitance 396 is connected which is in turn connected by a conductor 39'! to a capacitance 398 at a point 399, the capacitance 398 being grounded as at 469. A conductor 49! runs from the heater filament connection point 386 of the electron tube 342 to a point 492 which joins a lead from the screen grid 311 and a conductor 483 from the connection point 399 of the capacitances 396 and 398, a resistor 494 completing the connection from the point 492 to ground at 499. From the control grid 343 of the electron tube 342 a conductor 495 having a resistor 496 therein leads to the cathode 401 of the photo-electric cell 344. The conductor 405 and resistor 496 are shielded to prevent capacitance between the conductor 495 and the system. The photo-electric cell 344 has an anode 498 from whence a conductor 409 runs to ground as at 4H]; another conductor 4! runs from the shield M2 and joins the ground conductor 499 at a connection point 4!3. There is a conductor 4H4 running from the connection point M5 on the conductor 495 to a capacitance H6 which is connected to the transformer secondary portion 234 at a connection point 4 1.

The operative relationship of the various parts of the system as is shown in Fig. 6 corresponds to the initial condition of the system prior to energization. When the main power switch 254 17 is closed the transformer 261 is energized and the system is ready to function subject to the various controls therein. The electron tube cathode heater coil 316 is energized by the transformer secondary portion 265 as soon as current is supplied to the transformer primary 260 and the electron tube 342 then begins to heat in preparation for its functioning later on. When the thermostat 261 closes calling for heat a circuit is completed from the transformer secondary portion 254 through the conductors 218 and 215, 4'

the closed contacts 211 and 212 of the thermostat 261, and the conductors 216 and 219 to the relay coil 280. From the relay coil 280 the ,cirr cuit continues through the conductor 345, the reset switch 336, the conductor 346, the closed contacts 284 and 281, the conductor 341, the resistor 341 of the timer switch 331, the couductor 348, the closed contacts 311 and 312 of the switch 310, the conductors 351 and 353, and the conductor 355 terminating back at the transformer secondary portion 264. This last-named circuit as described is completed through the relay coil 230 but the voltage drop through the resistor 341 is so great that there is not sufficient current through the relay coil 280 to cause the relay switch 231 to close. While this great voltage drop is taking place through the resistor 341, the same is heating and transmitting heat to the bimetal element 340 so that after a predeter- F,

mined time the bimetal element 340 will warp to such an extent that the contacts 338 and 339 of the timer switch 331 will close thus establishing a shunt circuit of lower resistance through the bimetal element 340 so that the relay coil 283 is able to function and close the relay switch 281. When the relay switch 281 closes, the contacts 284 and 281 are broken apart and the contacts 285, 288, 286 and 291 respectively are closed. The closing of the contacts 285 and 288 establish a holding circuit for the relay coil 280 which is completed through the closed contacts 285 and 288, the resistor 354 and the conductors 353 and 355 terminating at the transformer secondary portion 264. The resistor 354 which is connected in series with the relay coil 280 in the holding circuit for the relay switch 281 is of a suflicient re: sistance to cause a voltage drop therethrough which will render the relay coil 2 80 inoperative or cause the relay switch 281 to open should the v voltage in the circuit drop below a predetermined minimiun value. The closing of the holding circuit for the relay coil 280 and the opening of the contacts 284 and 281 cause the circuit through the timer switch 331 to be broken and the holding circuit to be independent of the circuit through the timer switch 331. At the time the system is first energized and prior to the closing of the thermostat 261 and the relay switch 261 there is a circuit established from the cathode 315 of the electron tube 342 through the conductors 385 and 386, the closed contacts 311 and 312 of the switch 310, the conductors 351, 353, 355 and 381, the transformer secondary portion 266, the conductors 3.88 and 390 to the relay coil 319 of the relay switch 315, the circuit being completed by the conductors 391 and resistor 393 leading back to the anode 318 of the electron tube 342. Since this circuit operates through the closed contacts of .the switch 310 and (as will be explained later) since the switch 310 will be opened upon activation of the electron tube 342, this circuit functions as a fsafety for the system in the event that the control grid of the electron tube 3.42 should become shor ed 18 giving a false indication of flame while the system is in an off position. When the contacts 286 and 291 of the relay switch 281 are closed a circuit is completed from the hot conductor 262 through the conductor 359, the closed contacts 286 and 291 and the conductor 360 to the switch 291. Through the closed contacts 301 and 303 of the switch 291 a circuit is completed through the motor 251 by the conductors 363, 355 and 366. Through the closed contacts 300 and 302 of the switch 291 the circuit is completed through the ignition coil primary 369 by the conductors 361 and 311, a branch circuit running from connection point 313 on conductor 361 over the conductors 312 and 314 through the heater coil 328 of the bimetal element 321. It is seen then that upon energization of the system the primary of the transformer 261 is energized thus energizing a circuit for the heater coil 316 of the electron tube 342. When the thermostat 261 closes the circuit is completed through the coil 280 of the relay switch 281, but due to the voltage drop through the timer switch 331 the relay switch 281 is not able to function. After a predetermined time the timer switch 331 establishing a shunt circuit around the high resistor therein permitting the relay switch 281 to close, the aforementioned predetermined time for operation of the timer switch 331 being at least that required for the heating of the electron tube 342. When the relay switch 281 is closed a holding circuit is established for the relay coil 280 and circuits are energized through the control switch 231 to the motor, the ignition and the heater element of the bimetal element 321. At this point in the operation the system is ready to function subject to the occurrence of flame at the burner 249. If upon the aforementioned energization of the circuits through the motor and the ignition, the system should function normally and flame occur in the burner 249 the photo-electric cell 344 will function to drain a negative potential from the control grid 343 of the electron tube 342 thus permitting the passage of electric current therethrough. The photo-electric cell 344 is housed in a casing 344 to shield it from response to extraneous light rays not emitted from the burner flame. Upon the electron tube 342 becoming conductive the aforementioned circuit from the cathode of the electron tube through the coil 319 of the relay switch 315 is completed and the relay switch 31 5 will close. The closing of the relay switch 315 will cause the contact arm 31! to move the abutment member 318 against the pivoted member 305 moving the same free of the abutment 304 permitting the switch 291 to open and simultaneously engage the contact arm 309 of the switch 310 with the Upper portion 308 of the pivoted member 305 causing the switch 310 to open. As was described heretofore the fixed contacts 323 and 324 of the relay switch 315 are mounted upon flexible supporting members 325 and 326 so that the movable contacts 321 and 322 upon closing movement may contact the fixed contacts before the switch 310 is open. (This step in the operation ofthe system is illustrated in Fig. 7. The contacts of the relay switch 315 are shown closed and the switch 310 has not yet opened.) The flexibility of the fixed contacts permits the movable contacts of the relay switch 315 to have a predetermined amount ,of overtravel during which overtravel the pivoted member 305 is moved .clear,of'the abutment 304 to permit the 19 switch 291 to open and the switch 310 is opened by engagement of the upper portion 308 of the pivoted member 305 with the contact-carrying arm 309. This step of the operation is shown in Fig. 8 in which the movable contact arms 316 and 311 have moved past their point of engagement with the fixed contacts and the switches 291 and 310 are opened.) At this point, with the switch 291 open and the relay switch 315 closed, a second circuit is established for the motor and a second circuit is established for holding closed the relay switch 315. The second motor circuit runs from the hot conductor 232 through the conductor 359, the closed contacts 286 and 291 of the relay'switch 281, the conductors 330 and 361, the closed contacts 321 and 323 of the relay switch 315, the conductors 383 and 363 to the connection panel 255 and thence by conductors 365 and 366 through the motor 251 to the ground conductor 251. The second cathode circuitfor holding the relay switch 315 closed runs from the cathode 315 of the electron tube 342 by conductor 385 to the flexible contact arm 326 of the relay switch 3 I 5, through the closed contacts 322 and 324, the conductors 351, 353, 355 and 381, the transformer secondary portion 266, the conductors 388 and 3911 to the relay coil 319, the circuit being completed by conductor 391 and resistor 393 to the anode 318 of the electron tube 342. As was pointed out in the mechanical operation of the relay switch 315 against the pivoted member 305, these circuits through the contacts of the relay switch 315 are established before the switches 291 or 310 are opened thus providing a continuous circuit independent of the opening of the switches 310 and 291. The opening of the switch 291 de-energizes the first-named circuit to the motor 251, the re-establishment of which has already been described, and the circuit to .the ignition transformer 310 and the heater coil 328 for the bimetal element 321. It is seen then that in the normal sequence of operation of this system upon energization and upon calling for heat by the thermostat 261, the relay switch 281 is closed after a predetermined delay caused by the time switch 331 to permit the electron tube 342 to heat, the closing of the relay switch 281 being operable to energize the circuits to the motor 251, the ignition transformer 310, and the heater coil 328 for the bimetal element 321. The occurrence of flame then at the burner 249 will cause the electron tube 342 to become conductive thus completing the circuit through the relay switch 315 causing the same to close thus opening the circuits for the motor, the ignition, the heater coil and the electron tube, a second circuit for the motor and for the electron tube be.- ing established simultaneously with the opening of the aforementioned circuits. When the system is energized, the thermostat 281 is calling for heat and the relay switch 281 is closed. If the relay switch 315 should fail to close for any reason (e. g. failure of flame at the burner, failure of the electron tube 342, or a break in the relay circuit) the heater coil 328 for the bimetal element 321 will continue to heat, to operate as a safety means for moving the bimetal element 321 into engagement with the pivoted member 305 to move the same clear of the abutment "304 to permit the switch 291 to open and simultaneously to open the switch 310. At this point in the safety operation the system is in substantially the same condition as that shown in the form of the invention of Fig. 2 in that the switches 291 and 310 are open and the relay switch 281 is closed by its holding circuit. The system at this point is in a lock-out position from which position the system cannot function until the switches 231 and 310 are closed. In this form of the invention, however, there is a flexible stop member 330 which is engageable with the bimetal element 321 upon operation thereof to prevent the same from returning to its initial position after safety operation so that the system may not be operated again after safety operation until a check has been made to determine the cause of the failure. With the bimetal element 321 locked by the stop member 330 in its operated position the pivoted member 305 cannot return to its initial position and so even though the circuit through the thermostat 261 might be opened permitting the relay switch 281 to return to its initial position and closing the switch 291 by engagement of the pivoted contact arm portion 295 with the contact arm 295 the pivoted member 385 would still hold open the switch 310 thus preventing reenergization of the relay coil 280 until the bimetal element 32'! is permitted to return to its initial position, When the reset member 331 is pushed into engagement with the stop member 330, the stop member 330 is moved clear of engagement with the bimetal element 321 and the same is permitted to return to its initial position.

As an additional safety feature the reset arm portion 333 is engageable with the pivoted member 3015 so that the reset member 331 may not be lodged into operated position and the stop member 330 thereby rendered ineffective. (If the reset member 331 should be held in operated position the reset arm portion 333 acting through the pivoted member 305 will function to hold the switch 310 open thus preventing operation of the system.) -The projecting arm portion 334 of the reset member 331 is cooperable upon movement to engage the reset switch 336 to open the same simultaneously with the resetting of the bimetal element 321 thereby breaking the circuit through the relay coil 280 independently of the thermostat 231. The described step in the sequence of operation of the system in which the bimetal element 321 has moved the pivoted member 305 to safety position is clearly illustrated in Fig. 9. In operation if the fuel should fail to ignite in the burner 249 upon initial operation of the system the bimetal element 321 will move to safety position thus locking the system as described until the reset member has been operated. If, upon initial operation, the fuel should ignite at the burner 249 and the system function normally as heretofore described, but during the operation the flame, for some reason, should go out the electron tube 342 would then be blocked for passage of current therethrough thus causing the relay switch 315 to open to de-energize the motor circuit to prevent further supply of fuel to the burner 249. At this point in the operation since the bimetal element 321 has not moved to safety position and the switches 291 and 310 are open the thermostat 261 must be opened or the reset member moved to open the reset switch to break the holding circuit through the relay coil 280 to permit the relay switch 231 to return to its initial position to close the switch 291 and permit the pivoted member 305 to return to its initial position and the switch 310 to close. The relay switch 281 is able to close the switch 291 because the spring 282 is stronger than the spring 298. After the circuit has been opened through the thermostat 231 and the relay switch 28! a subsequent closing of the contacts of the thermostat 261 will cause the system to function as though it were being started initially, that is, the system will go through its normal cycle of operation and should the fuel fail to ignite at the burner 249 the bimetal element'32l will move to safety position as described heretofore.

The systems as shown are applicable especially to the control of gun or rotary types" of liquid fuel burners having a blower and means for supplying fuel in a fine spray to the burner. These systems, however, would also be adaptable to the control of pot type liquid fuel burners wherein an electric blower supplies a forced draft of air to the burner or where the supply of fuel to the burner is controlled by an electric valve such as a solenoid valve. It would also be possible to adapt these control systems to the burning of solid fuel in a finely divided state wherein a powdered fuel and air mixture would be supplied to the burner by a blower which could be controlled by the system. It should therefore be evident that although the systems have been described as specifically applicable to gun type oil burners, it is not intended that this invention shall be so limited.

Having thus described the invent-ion, what is claimed and is desired to be secured by Letters Patent of the United States is:

1.111 a control device, a circuit including a switch, a relay switch operable to control energization of said circuit, a second circuit including a third switch, said third switch being initially closed, a pivoted member engaging and holding closed said first-named switch, said pivoted member being operable upon predetermined movement to permit said firstmamed switch to open and to open said third switch, electric timing means operable after a predetermined time as safety means to move said pivoted member through said predetermined movement, and means including a second relay switch arm operable to engage said pivoted member and to move the same to open said first-named and said third switches.

2. In a control device, a circuit including a switch, a relay switch operable to control energization of said circuit, a second circuit including a third switch, said third switch being initially closed, a pivoted member engaging and holding closed said first-named switch, said pivoted member being operable upon predetermined movement to permit said first-named switch to open and to open said third switch, a third circuit connected in parallel with said first-named circuit, a second relay switch having contacts in said third circuit, said second relay switch having a contact carrying pivoted member operable upon movement to close said contacts in said third circuit and also to engage and move said first-named pivoted member through said predetermined movement thereby to open said first-named and said third switches.

3. In a control device, a circuit including a switch, a relay switch operable to control energization of said circuit, a second circuit including a third switch, said third switch being initially closed, a pivoted member engaging and holding closed said first-named switch, said pivoted member being operable upon predetermined movement topermit said first-named switch to open and to open said third switch, a bimetal element, an electric-heating coil for'said bimetal "element, said bimetal element being operable upon heating for a predetermined time to move said pivoted member through said predetermined movement thereby to open said first-named and said third switches for safety operations, a second relay switch having a pivoted member operable upon closing movement to engage and move said first-named pivoted member through said predetermined movement thereby to open said firstnamed and said third switches.

4. In a control device, afirst circuit and a second circuit, a switch having two pairs of contacts for controlling said circuits, a relay switch having a pair of contacts in said first and said second circuits and operable to control energization of said circuits, at third circuit, a second relay switch having a pair of contacts in and controlling said third circuit, said second relay switch being normally open, a fourth circuit including a fourth switch, a pivoted memberengaging and holding closed said first-named switch, said pivoted member being operable upon a predetermined movement to permit said first-named switch to open and to open said fourth switch, said second relay switch having a pivoted contact-carrying arm engageable with and operable to move said pivoted member, said second relay switch being operable upon closing movement to move said pivoted member so that said first-named switch and said fourth switch may open thus de-energizing said first, said second, and said fourth circuits and energizing said third circuit, and safety means operable to move said pivoted member to open said first-named switch upon failure of said second relay switch to close.

5. In a control device, a first circuit and a sec ond circuit, a switch for controlling said circuits, a relay switch operable to control energization of said circuits, a third circuit connected in parallel with said first circuit, a second relay switch for controlling said third circuit, said second relay switch being normally open, a fourth circuit including a fourth switch, a pivoted member engaging and holding closed said first-named switch, said pivoted member eing operable upon a predetermined movement to permit said firstnamed switch to open and to open said fourth switch, said second relay switch having a pivoted contact-carrying arm engageable with and operable to move said pivoted member, said second relay switch being operable upon closing movement to move said pivoted member so that said first-named switch and said fourth switch may open thus de-energizing said first, said second, and said fourth circuits and energizing said third circuit, a bimetal element, an electric heating coil and circuit for said bimetal element, said bimetal element being operable upon heating to move said pivoted member, and said heating coil and bimetal element being operable as timing means and as safety by moving said pivoted member and thereby opening said first-named switch upon failure of said second relay switch to function within apredetermined time.

6. In a control device, a first circuit and a second circuit, a switch having two pairs of contacts for controlling said circuits, a relay switch having a pair of contacts in said first and said second circuits and operable to control energization of said circuits, a transformer, a third circuit from said transformer including a third switch and operable to energize said relay switch, a fourth circuit, a second relay switch having a pair of contacts in and cont-rolling said fourth circuit, said second relay switch being normally open, a holding circuit for said first-named relay 23 switch operable upon closing of said first-named relay switch to hold the same closed independent- 1y of said third circuit, a pivoted member engaging and holding closed said first named switch, said pivoted member being operable upon a predetermined movement to permit said firstnamed switch to open and to open said third switch, said second relay switch having a pivoted contact-carrying arm engageable with and operable to move said pivoted member, said second relay switch being operable upon closing movement to move said pivoted member so that said first-named switch and said third switch may open thus de-energizing said first, said second, and said third circuits and energizing said fourth circuit, and safety means operable to move said pivoted member to open said first-named switch upon failure of said second relay switch to close.

7. In a control device, a circuit including a control switch, a second circuit in parallel with said first-named circuit and including a second control switch, said second switch including an arm operable upon closing movement to open said first-named switch, means for controlling the energization of said first-named circuit, means for controlling said control means, safety means operable to open said first-named switch upon failure of said second switch to function, stop means operable to prevent said safety means from returning to its initial state after functioning, a reset mechanism operable upon movement to move said stop means to permit said safety means to return to its initial state, and said reset mechanism being furtheroperable to actuate said second-named control means to prevent energization of said first-named circuit.

8. In a control device for controlling a burner motor and electric ignition means, a motor circuit and an ignition circuit, a switch operable to control said circuits, a relay switch for controlling energization of said circuits, a third switch for controlling energization of said relay switch, a second motor circuit, a second relay switch for controlling said second motor circuit, a pivoted member engaging and holding closed said firstnamed switch, said pivoted member being operable upon movement to permit said first-named switch to open and to open said third switch, a holding circuit for said first-named relay switch operable to hold the same closed upon opening of said third switch, said second relay switch being operable upon closing movement to move said pivoted member thereby opening said first-named and said third switches, a bimetal element operable to move against said pivoted member upon heating, an electric heating coil for said bimetal element, said heating coil and said bimetal element being operable as safety means to move said pivoted member to open said first-named and said third switches upon failure of said second relay switch to close within a predetermined time, a flexible stop member operable to (prevent said bimetal element from returning to its initial position upon cooling, a reset member operable upon movement to engage and move said stop memberthereby to permit said bimetal element to return to its initial position, and said reset member being further operable upon movement to engage and move said pivoted member.

9. In a control device, a circuit including a switch, a relay switch operable to control energization of said circuit, a second circuit including a third switch, said third switch being initially closed, a pivoted member engaging and holding closed said first-named switch, said pivoted mom-- her being operable upon predetermined movement to permit said first-named switch to open and to open said third switch, a third circuit connected in parallel with said first-named circuit, a second relay switch having contacts in said third circuit, an electron tube in circuit with and controlling said second relay switch, and said second relay switch having a contact carrying pivoted member operable upon movement to close said contacts in said third circuit and also to engage and move said first-named pivoted member through said predetermined movement thereby to open said first-named and said third switches.

10. In a control device, a circuit including a switch, a relay switch operable to control energization of said circuit, a second circuit including a third switch, said third switch being initially closed, a pivoted member engaging and holding closed said first-named switch, said pivoted member being operable upon predetermined movement to permit said first-named switch to open and to. open said third switch, a third circuit connected in parallel with said first-named circuit, a second relay switch having contacts in said third circuit, an electron tube in circuit with and controlling said second relay switch, said second relay switch having a contact carrying pivoted member operable upon movement to close said contacts in said third circuit and also to engage and move said first-named pivoted member through said predetermined movement thereby to open said first-named and said third switches, a bimetal element, an electric heating coil for said bimetal element, and said bimetal element being operable after heating for a predetermined time to move said pivoted member the distance necessary to open said first-named switch.

11. In a control device for controlling a burner motor and electric ignition means, a motor circuit and an ignition circuit, a switch having two pairs of contacts and operable to control said circuits, a relay switch operable to control energization of said circuits, a third switch operable to control said relay switch, a second motor circuit in parallel with said first motor circuit, a second relay switch having contacts in and controlling said second motor circuit, said second relay switch being normally open, an electron tube in circuit with the coil of said second relay switch and operable to control its operation, a pivoted member engaging and holding closed said firstnamed switch, said pivoted member being operable upon a predetermined movement to permit said first-named switch to open, said second relay switch having a [pivoted contact-carrying arm which is operable upon closing movement to energize said second motor circuit and to engage and move said pivoted member to open said firstnamed switch, said second relay switch being operable upon activation of said electron tube to close thus moving said pivoted member to open said first-named switch thereby de-energizing said motor and ignition circuits and energizing said second motor circuit, and safety means for de-energizing said motor and ignition circuits upon failure of said electron tube to function.

12. In a control device for controlling a burner motor-and electric ignition means, a motor circuit and an ignition circuit, a switch having two pairs of contacts and operable to control said circuits, a relay switch operable to control energization of said circuits, a third switch operable to control said relay switch, a second motor circuit in parallel with said first motor circuit. a

second relay switch having contacts in and controlling said second motor circuit, said second relay switch being normally open, an electron tube in circuit with the coil of said second relay switch and operable to control its operation, a pivoted member engaging and holding closed said first-named switch, said pivoted member being operable upon a predetermined movement to permit said first-named switch to open, said second relay switch having a pivoted contactcarrying arm which is operable upon closing movement to energize said second motor circuit and to engage and move said pivoted member to open said first named switch, said second relay switch being operable upon activation of said electron tube to close thus moving said pivoted member to open said first named switch thereby pie-energizing said motor and ignition circuits and energizing said second motor circuit, a bimetal element, an electric heating coil for said bimetal element, and said bimetal element being operable upon predetermined heating as a safety means to move said pivoted member to open said first-named switch to deenergize said motor and ignition circuits upon failure of said electron tube to function within a predetermined time.

13. In a control device for controlling a burner motor and electric ignition means, a motor circuit and an ignition circuit, a switch having two pairs of contacts and operable to control said circuits, a relay switch operable to control energization of said circuits, a third switch operable to control said relay switch, a second motor circuit, a second relay switch for controlling said second motor circuit, said second relay switch being normally open, an electron tube in circuit with the coil of said second relay switch and operable to control its operation, timing means operable to prevent energization of said firstnamed relay switch until sufficient time has passed for said electron tube to become adequately heated, a pivoted member engaging andholding closed said first-named switch, said pivoted member being operable upon a predetermined movement to permit said first-named switch to open, said second relay switch having a pivoted contact-carrying arm which is operable upon movement to engage and move said pivoted member, said second relay switch being operable upon activation of said electron tube to close thus moving said pivoted member so that said first-named switch may open thereby deenergizing said motor and ignition circuits and energizing said second motor circuit, a bimetal element, an electric heating coil for said bimetal element, said bimetal element being operable upon heating to move said pivoted member, and said bimetal element being further operable as a safety means to open said first-named switch to de-energize said motor and ignition circuits upon failure of said electron tube to function within a predetermined time.

14. In a control device for controlling a burner motor and electric ignition means, a motor circuit and an ignition circuit, a switch having two pairs of contacts and operable to control said circuits, a relay switch operable to control energization of said circuits, a third switch operable to control said relay switch, a second motor circuit, a second relay switch for controlling said second motor circuit, said second relay switch being normally open, an electron tube in circuit with the coil of said second relay switch and operable to control its operation, timing means operable to prevent energization of said first-named relay switch until sufiicient time has passed for said electron tube to become adequately heated, a pivoted member engaging and holding closed said first-named switch, said pivoted member being operable upon a predetermined movement to permit said firstnamed switch to open, said second relay switch having a pivoted contact-carrying arm which is operable upon movement to engage and move said pivoted member, said second relay switch being operable upon activation of said electron tube to close thus moving said pivoted member so that said first-named switch may open thereby de-energizing said motor and ignition circuits and energizing said second motor circuit, a bimetal element, an electric heating coil for said bimetal element, said bimetal element being operable upon heating to move said pivoted member, said bimetal element being further operable as a safety means to open said first-named switch to de-energize said motor and ignition circuits upon failure of said electron tube to function within a predetermined time, a flexible stop member operable to prevent said bimetal element from returning to its initial position upon cooling, a reset member engageable with said stop member upon movement and operable to move said stop member to permit said bimetal element to return to its initial position, and said reset member being further operable to engage and move said pivoted member to open said third switch thereby to prevent operation of said control device so long as said reset member is in operated position.

15. In a control device for controlling a burner motor and electric ignition means, a motor circuit and an ignition circuit, a switch having two pairs of contacts and operable to control said circuits, a relay switch operable to control energization of said circuits, a third switch operable to control said relay switch, a second motor circuit, a second relay switch for controlling said second motor circuit, said second relay switch being normally open, an electron tube in circuit with the coil of said second relay switch and operable to control its operation, an electrical resistor operable to cause a sufiicient voltage drop therethrough to prevent functioning of said first-named relay switch, a thermostatic switch responsive to the heat output of said resistor and operable to close a shunt circuit of less resistance than said resistor after a predetermined exposure to the heat of said resistor, said predetermined exposure being of the same duration as the heating time for said electron tube, a pivoted member engaging and holding closed said first-named switch, said pivoted member being operable upon a predetermined movement to permit said first-named switch to open, said second rela switch having a pivoted contact-carrying arm which is operable upon movement to engage and move said pivoted member, said second relay switch being operable upon activation of said electron tube to close thus moving said pivoted member so that said first-named switch may open thereby de-energizing said motor and ignition circuits and energizing said second motor circuit, a bimetal element, an electric heating coil for said bimetal element, said bimetal element being operable upon heating to move said pivoted member, said bimetal element being further operable as a safety means to open said first-named switch to de-energize said motor and ignition circuits upon failure of said electron tube to function within a predetermined time, a flexible stop member operable to prevent said bimetal element from returning to its initial position upon cooling, a reset member engageable with said stop member upon movement and operable to move said stop member to permit said bimetal element to return to its initial position, and said reset member being further operable to engage and move said pivoted member to open said third switch thereby to prevent operation of said control device so long assaid reset member is in operated position 16. In a control device for controlling a burner motor and electric ignition means, a motor circuit and an ignition circuit, a switch having two pairs of contacts and operable to control said circuits, a relay switch having a plurality of contacts and operable to control energization of said circuits, a second motor circuit, a second relay switch for controlling said second motor circuit, said second relay switch being initially open, an electron tube in circuit with and-controlling said second relay switch; a fourth switch having two pairs of contacts, one pair of which are initially closed and one pair initially open; said last-named closed contacts being in circuit with the coils of said first named and said second relay switches, said last-named open contacts being in circuit with the coil of said second relay switch, a pivoted member engaging and holding closed said first switch, said pivoted member being operable upon partial movement to engage said fourth switch to open the closed contacts and to close the open contacts thereof and upon full movement to permit said first switch to open, said second relay switch being engageable with said pivoted member on closing movement, and said second relay switch being responsive to the activation of said electron tube and upon closing movement being operable to move said pivoted member to open said first switch thereby de-energizin said ignition circuit and said first-named motor circuit and energizing said second motor circuit.

17. In a control device for controlling a burner motor and electric ignition means, a motor circuit and an ignition circuit, a switch having two pairs of contacts and operable to control said circuits, a relay switch having a plurality of contacts and operable to control energization of said circuits, a second motor circuit, a second relay switch for controlling said second motor circuit, said second relay switch being initially open, an electron tube in circuit with and controlling said second relay switch; a fourth switch having two pairs of contacts, one pair of which are initially closed and one pair initially open; said last-named closedcontacts being in circuit with the coils of said first-named and said second relay switches, said last-named open contacts being in circuit with the coil of said second relay switch, a pivoted member engaging and holding closed said first switch, said pivoted member being operable upon partial movement to engage said fourth switch to open the closed contacts and to close the open contacts thereof and upon full movement to permit said first switch to open, said second relay switch being engageable with said pivoted member on closing movement, said second relay switch being responsive tothe activation of said electron tube and upon closing movement being operable to move said pivoted member to open said first switch thereby de-energizing said ignition circuit and said first-named motor circuit and energizing said second motor circuit, a bimetal element, an electric heating coil for said bimetal element, said bimetal element being operable to move upon heating to engage and move said pivoted member, said bimetal element and heating coil being operable as a timing means for actuating said fourth switch to break and to subsequently re-establish the circuit through said second relay switch thereby delaying the operation of said second relay switch until sufiicient time has passed for said electron tube to become adequately heated, and said bimetal element being further operable as a safety means to move said pivoted member to open said first switch and de-energize said motor and ignition circuits upon failure of activation of said electron tube within a predetermined time.

FRED B. AUBERT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,953,425 Miller Apr. 3, 1934 2,138,244 Raney Nov. 29, 1938 2,185,317 Schmieding Jan. 2, 1940 2,274,384 Scanlan Feb. 24, 1942 2,345,399 Jones Mar. 28, 1944 2,346,308 Isserstedt Apr. 11, 1944 2,351,622 Malone June 20,1944 2,384,372 Eaton Sept. 4, 1945 2,446,029 Tramontini July 27, 1948

Images