US2662589A

US2662589A - Electrical control system for liquid fuel burners

Info

Publication number: US2662589A
Application number: US774825A
Authority: US
Inventors: Fred B Aubert
Original assignee: Individual
Current assignee: Individual
Priority date: 1947-09-18
Filing date: 1947-09-18
Publication date: 1953-12-15
Anticipated expiration: 1970-12-15

Description

Dec. 15, 1953 F. B. AUBERT 2,662,589

ELECTRICAL CONTROL SYSTEM FOR LIQUID FUEL BURNERS Filed Sept. 18, 1947 2 Sheets-Sheet l 28 ooocoooc finausea-- Ila INVENTOR.

A in) ATTORNEY Dec. 15, 1953 F U E 2,662,589

ELECTRICAL CONTROL SYSTEM FOR LIQUID FUEL BURNERS Filed Sept. 18, 1947 28 OOOOOOOO- 2 Sheets-Sheet 2 FIG.2

INVENTOR. 4 6

Patented Dec. 15, 1953 UNITED STATES PAT ELECTRICAL CONTROL SYSTEMFOR LIQUID FUEL BURNERS 9-Claims. 1

This invention relates to new and useful improvements in control systems for liquid fuel burners.

One of the objects of this invention is to provide an improved control system for liquid fuel burners.

Another object of this invention is to provide a control system for a liqui fuel burner having controllable fuel vaporization means.

Another object of this invention is to provide a control system for liquid fuel burners which is easily constructed. and assembled and inexpensive to manufacture.

Other objects of this invention will become apparent from time to time through the specification and claims as hereinafter recited.

In the accompanying drawings to be taken as a part of this specification, there are clearly and fully illustrated two preferred embodiments of this invention, in which drawings- Figure 1 is view in vertical cross-section of a pot type liquid fuel burner having a fuel vaporization'member and diagrammatically showing a control system therefore, and

Fig. 2 is a view of a burner and fuel vaporization member similar to that in Fig. 1 but having a different control system therefor.

Referring to the drawing by characters of'reference, in Fig. 1 there is shown a liquid fuel burner I having a pot 2 and arecessed fuel well portion 3. The pot 2 has a plurality of air supply holes 4 therein and is surrounded by an air supply jacket E having a cover member 6 and being supplied with air by a blower l. The

fuel well portion 3 opens upward. into the pot 2 through an aperture 3 in the lower wall 9.

There is a fuel vaporization member lil-positioned in the fuel well portion 3 and extending upwardly into the pot 2. The member It has an enlarged hollow end portion H and a smaller solid rod portion l2. In commercial construction the fuel well portion 3 and fuel vaporization member in would be cylindrical in shape although the burner would function with these members constructed in other shapes. A fuel supply conduit I3 opens into the lower side wall of the fuel well portion 3 through an aperture 14 for supplying fuel for combustion in the burner. The member H3 is operable upon heating to vaporize liquid fuel coming thereagainst for combustion and is of such a size relative to the fuel well portion 3 that a very small annular space is enclosed between the member It and fuel W811. portion 3 so thata large area of heating surface of the member 'Ifl'is provided for a small amount of fuel thereby increasing the efficiency of the transfer of heat for vaporizing fuel. Positioned inside the hollow end portion of the fuel vaporizing member if: for heating the fuel supplied to the fuel well portion 3 prior to combustion is an electrical resistance heater coil I-carried in an insulating member It. The rod portion [2 of the fuel vaporizing member I0. extendsupward through the pot 2 into the zone of combustion and is operable during combustion to conduct heat to the hollow end portion l I for the vaporization of fuel. The supply of fuel through the conduit E3 to the fuel well portion 3 is controlled by an electrically controllable valve ll such as a solenoid valve or a valve operated by. an electrically energizable heat motor. The ignition of fuel in the burner not 2 is accomplished by an electric spark ignition ifl such as a spark plug.

The-control system for the burner l is supplied with power from a'main power source I9 to the primary of a transformer 2!. From the secondary 22 of the transformer 2| a conductor 23 leads to the fixed contact 2d of a room thermostat 2-5. The thermostat 25 is of a conventional type having a fixed contact 24 and a movable contact 26 carried by a bimetallic blade 21. The room thermostat has an electric heater coil 28 which functions as a compensator for fluctuations in temperature to which the thermostat responds. The heater coil 28 is connected by a conductor-29 to a resistor 30 which is in turn connected to the transformer secondary 20 as at 31. From the bimetal blade 27 of the thermostat 25 a conductor 32 runs to the coil 33 of the relay switch 34. The relay switch as is a bi-pole switch having two

fixed contacts

35 and 36 and two-movable contacts at and 38 carried by contact arms 39 and respectively, contact arms 39 and ii] beingconnected to each other for joint movement by a connecting member at of an electric insulating material. From the relay coil 33 a conductor fizruns to a connection point 43 on a conductor 44 which interconnects the fixed contact 35 and the fixed contact d5 of a thermostatic switch 4E. The thermostatic switch 45 has three fixed contacts '45. ll and 38 and three

movable contacts

49, 59 and 5!. The movable contact 69 is carried by a contact arm 52 and the movable contacts so and El are carried by a contact arm 53. The

contacts

45 and 49, 418 and Si are initially closed and the contacts 47 and 50 are initially open so that movement of the thermostatic switch 46 will open the closed contacts and close the open contacts. The

contact arms

52 and 53 are connected each to each by an actuating member 54 of an insulating material which is in turn connected to and actuated by a bimetallic blade 55. From the contact arm 52 of the switch 46 the conductor 56 connects with a conductor 51 which runs from the relay switch contact arm 39 to the connection point 3| on the transformer secondary 22. From the main power source l9 and connected in parallel with the transformer primary 29 a circuit runs by

conductors

58 and 59 to the electric motor 69 which drives the blower the circuit being completed by conductors GI and 62 back to the main power source l9. This last-mentioned circuit through the blower motor 69 is such that the blower I will be operating at all times that the system is energized. From a connection point 63 at the junction of

conductors

58 and 59 in the blower motor circuit, a conductor 64 runs to the fixed contact 36 of the relay switch 34. From the contact arm 49 of the relay switch 34

conductors

65 and 66 run to the movable contact arm 53 of the thermostatic switch 46. From the fixed contact 48 of the thermostatic switch 46 a conductor 6'! runs to a conductor 66 which is in turn connected to an electrical resistance heater l5, the circuit being completed by a conductor 69 which joins the conductor 62 at a connection point 10 thus completing the circuit back to the main power source IS. A conductor l! runs from a connection point 12 at the juncture of conductors 6'1 and 68 to the primary 13 of an ignition transformer 14. The circuit through the ignition transformer 14 is completed back to the main power source H! by conductors i5 and 19 which connect with the conductor 69 at a connection point 17. The conductor 15 leads to the fixed contact 16 of a thermostatic switch 19, the contacts of the switch 19 being open so that the circuit through the ignition transformer '14 is broken. The thermostatic switch 19 has a fixed contact 18 and a movable contact 39 which is carried by a contact arm ill from which runs the conductor 16. The switch 19 is actuated by a bimetallic blade 82 having an actuating member 83 of an insulating material connected to the contact arm 8| for movement thereof. From the fixed contact 41 of the thermostatic switch 46 a conductor 84 runs to the electrically controllable valve H which is connected by a conductor to a connection point 86 on the conductor 16, the circuit being completed by conductors I6, 69, and 62 back to the main power source. There is a conductor 86 which runs from a connection point 81 at the junction of

conductors

65 and 66 to a terminal point 88 which is connected to the movable contact arm 89 of a gas tube warp switch 90. The gas tube war switch 99 is of the conventional type having a fixed contact 9| and a movable contact 92 which is carried by a contact arm 89 of a bimetallic thermostatic material and having an ionizing member 93 which functions to heat the gas within the tube to cause the contact arm 89 to warp closing the contacts 9| and 92. The fixed contact 9| of the gas tube warp switch 99 is connected by the conductor 94 to a connection point 95 on the conductor 84 at the valve ll. The ignition transformer secondary 96 is connected by a conductor 91 to the spark electrode 98 of the spark ignition in the pot 2. The ignition transformer secondary 96 is also connected to a pair of inductive coils 99 and I00 which are grounded as at NH. The coil I00 is connected by the capacitor I92 to a connection point |03 on the conductor 91 leading to the ignition electrode 98.

A. The coil 99 is connected to the ionizing electrode 93 in the gas tube warp switch and is operable to actuate the same.

In operation this form of the invention functions as follows:

When current is supplied to the system as from the main power source |9 the transformer 2| is energized for operation and the blower motor 60 is energized by the circuit through the

conductors

58, 59, 6| and 62. At this point in the operation the blower is turned on and is supplying air to the space enclosed by the jacket 5 and the burner pot 2 to support combustion in the burner. When the room thermostat 25 closes calling for heat, a circuit is completed from the transformer secondary 22 by conductor 23, the

closed contacts

24 and 26 of the thermostat 25, and the conductor 32 to the relay coil 33. The circuit through the relay coil 33 is completed for initial operation through the

conductors

42 and 44, the

closed contacts

45 and 49 of the thermostatic switch 45 and the conductors 56 and 51 leading back to the transformer secondary 22. When the relay coil 33 is thus energized the movable contacts 31 and 38 close against the fixed

contacts

35 and 36 respectively. When

contacts

35 and 31 of the relay switch 34 are closed a holding circuit for the relay coil 33 is established through the

closed contacts

35 and 31 and the conductor 57 leading back to the transformer secondary 22. When the relay contacts 36 and 38 are closed a circuit is completed by

conductors

58 and 34, the closed contacts 36 and 38, the

conductors

65 and 66, the

closed contacts

43 and 5| of the thermostatic switch 46, and the conductors 6'! and 68 through the electrical resistance heater |5 in the hollow end portion of the fuel vaporization member II], the circuit being completed back to the main power source by

conductors

69 and 62. It is thus seen that when the room thermostat 25 closes calling for heat and energizing the relay switch 34 a circuit is completed through the electrical resistance heater I5 for heating the fuel vaporization member He.

The thermostatic switch 19 is positioned adjacent the fuel well portion 3 and is responsive to the temperature of the hollow end portion H of the fuel vaporization member H; which is heated by the electrical resistance heater i5. When the temperature of the fuel vaporization member ID and end portion reaches a predetermined level, such as that required for vaporization of fuel for initial operation, the bimetal blade 82 will move the contact 89 of the thermostatic switch 19 into engagement with the fixed contact 18. The closing of the contacts and E8 of the thermostatic switch 19 completes a branch circuit from the connection point E2 of the resistance heater circuit by way of conductor H to the ignition transformer primary 13 which is connected by conductor 15, the closed. contacts 8|] and I8, and the conductor 76 to the connection point 11 on the conductor 69 leading back to the main power source. Upon energization of the ignition transformer T4, the spark ignition I8 in the burner pot 2 will begin to function and is operable to ignite fuel vapors with which it comes in contact. Simultaneously with the occurrence of sparks in the burner pot 2 the inductive coils 99 and IE0 will operate through the ionizing electrode 93 to heat the gas tube warp switch 90 thereby to close the contacts 9| and 92. When the contacts 9| and 92 of the gas tube warp switch 99 are closed a branch circuit is established through the fuel control valve H by way of conductors 65' and 86 leading from the relay switch 3'4 to the gas tube warp switch 90 and conductor 94 leading from the warp switch 9D to the valve I7; the circuit from the valve II being completed by

conductors

85, 15, 69 and 62 back to the main power source. At this point in the operation of the system the electric heater I5 is energized for the vaporization of fuel, the ignition I8 is energized and the fuel control valve if is opened to permit the supply of fuel to the fuel well portion 3. When the fuel supplied to the fuel well portion 3 comes in contact with the fuel vaporization member I!) at its end portion II the fuel is vaporized and these vapors rise into the burner pot 2 to be ignited by the ignition I8. After ignition of the fuel and the occurrence'of continued combustion in the burner pot 2 the rod portion I2 of the fuel vaporization member It! is heated to a temperature considerably above that at the hollow end portion I I and heat therefrom is conducted down the member It to the hollow end portion II thereby raising the temperature of that portion above that maintained by the resistance heater I5. switch I is positioned adjacent the fuel well portion 3 and is responsive to the higher temperature of the hollow end portion H of the fuel vaporization member I8 when heated by the occurrence of combustion in the burner pot 2. When the hollow end portion I I of the fuel vaporization member I!) reaches a sufficient predetermined temperature above that required for response by the switch E9, the thermostatic switch 46 will move opening the

closed contacts

58 and 45, 4B and 5! and closing the open contacts ll and 5B. When the contacts 49 and d5 of the thermostatic switch 46 are op'enedthe circuit for initial energization of the relay coil 33 is broken but the coil 33 continues to be energized'by the aforementioned holding circuit. When the closed contacts 48 and 5I- are opened the circuit through the resistance heater I5 and the ignition transformer M is broken thus de-energizing the resistance heateri5 and ignition I8 permitting the warp switch contacts 9| and 9 2 to open. The opening of the gas tube warp switch contacts 9! and 92 breaks the circuit through the fuel control valve H but the closing of the contacts d-I and 58 of thethermostatic switch tiesta'blishes a second circuit therethrough. With theclosing of the contacts 4'! and 50 a new circuit is established for energization of the fuel control valve I by way of conductor 84 leading from the fixed contact '41 of the thermostatic switch 56 to the control valve I1 which circuit is completed as before, the new fuel valve control circuit merely bypassing the warp switch 90.

In summation, it is seen that when the thermostat closes calling for heat the relay switch l'i l is energized thus establishing a circuit through the resistance heater I5 to heat the fuel vaporization member II) for vaporization of fuel in the fuel well portion 3. Upon attainment of a predetermined temperature by the end portion II of the fuel vaporization member It, the thermostatic switch I9 closes completing the circuit through the ignition transformer It at which time'sparks occur in the burner and. the ionizing electrode 93 is energized andthe warp switch 96 is thus causedto close thereby'establishinga circuit. through the fuel supply control valve. H to permit the flow of fuel to the fuelwell portion .3. When fuel flows into the fuel well portion 13 and is vaporized by contact with the vaporization member I19, the'fuel vaporsrise into the humor The thermostatic pot 2 where they are mixed with air supplied-by the blower I and ignited by the ignition I 8. Upon the occurrence of combustion in the burner pot 2 the rod portion I2 is heated by the flames in the burner pot and this heat is conducted to the hollow end portion II causing the temperature of the same to rise above that produced by the electrical resistance heater I5. Upon attainment of a second and higher predetermined temperature by the hollow endportion II of the fuelvapor-ization member Ii] the thermostatic switch 45 is actuated causing the circuit to be broken through the resistance heater I 5 and ignition transformer I l and establishing a new circuit for energization of the fuel supply control valve I'I. At this point in the operation the heat for the fuel vaporization member If] is supplied by combustion in the burner pot 2 and the resistance heater I5 no longer being needed is de-energized. Correspondingly, the ignition i8 is de-energized. When the temperature of the space being heatedrises sufficiently to satisfy the thermostat 25, the same will open thus de-energizing the relay switch 34 and breaking the circuit to the fuel supply control valve I'I shutting off the supply of fuel and permitting the system to return to its original initial condition upon cooling of the fuel vapor-ization member II! and the thermostatic switches 4'6 and 79. Upon a subsequent calling for heat by the thermostat 25 the system will again function as heretofore described.

In the form of the invention shown in Fig. 2 the burner and fuel vaporization member and any of the parts of the control system therefor which are of similar construction to that shown in the form of the invention previously described and all parts common to both forms of the invention will bear common reference characters.

There is a burner I having a pot 2 Witha fuel well portion 3 opening into the lower wall 9 thereof. The pot 2 has a plurality of holes Atheroin for the supply of combustion air and is surrounded by an air jacket 5 having a cover member 6. The air jacket 5 in thisform of the invention is of slightly different construction from that shown in the previous form in that the jacketed air space also encloses the lower wall 9 of the burner pot '2 and there are a plurality of air supply holes 5* in the lower wall 9 for the supply of combustion air underneath. As in the previous form of the invention there is a blower l for supplying combustion air to the jacketed space enclosed by the jacket 5 and burner pot 21 There is a fuel vaporization member It having an enlarged hollow end portion II and a smaller solid rod portion I2 for vaporization of fuel supplied to the fuel well portion 3. There is a fuel supply conduit it which supplies fuel to the fuel well portion 3 through aperture It in the lower outside wall portion thereof. The fuel vaporization member it has an electrical re:- sistance heater I5 carried by a cylindrical insulating member It which is positioned inside. the hollow-end portion II thereof. The supply of fuel to the fuel well portion .3 is controlled by an electrically controllable valve I1 and the ignition of fuel in the burner pot 2 is accomplished by electrical spark ignition 38. There is an annular collar member IE4 which fits over the rod portion I2 of the fuel vaporization member Iii and restricts the flow of fuel vapor into the burner pot 2 by providing a very narrow annular space for the discharge of fuel vapors for ignition from the fuel well portion 3. The collar member Iii-i also functions to heat fuel vapors coming into the burner pot 2 to cause additional vaporization of any liquid particles entrained with the fuel vapors entering the pot. Electric current for the energization of the control system for this form of the invention is supplied from a main power source I9 to the primary 20 of a transformer 2I. From the secondary 22 of the transformer 2! a conductor 23 runs to the fixed contact 24 of a room thermostat 25. The room thermostat 25 is of conventional construction having a fixed contact 24 and a movable contact 25 carried by a thermostatic bimetal blade 21. There is a compensating heater coil 28 for the thermostat 25 which is connected to the blade 2? and is in turn connected by a conductor 23 and resistor 39 to a connection point 3I on the transformer secondary 22. From the bimetal blade 2! of the thermostat 25 a conductor 32 runs to the coil 33 of a relay switch 3 The relay switch 34 has two pairs of fixed

contacts

35 and 35 and two pairs of movable contacts 3'! and 38. The movable contacts 3! and 38 are carried by

contact arms

39 and 49 respectively which are connected each to each by an insulating member M for joint movement thereof. The relay coil 33 is connected by a conductor 42 to a con nection point 43 on a conductor M which runs from the fixed relay contact 35 to a connection point I65 on a conductor Int leading to a movable contact arm I01 of a thermostatic switch I08. The thermostatic switch I50 is carried by a bracket member I99 which is mounted on the lower wall III) of the air jacket 5 The air jacket 5 has an aperture HI for the insertion of the helical bimetal actuating member I52 of the thermostatic switch I08 into the jacketed air space surrounding the burner pot 2. The thermostatic switch I98 has two contact arms H3 and I! which are fixed to and actuated by a rod member II4 which is in turn operated by the helical bimetal element II2. In the thermostatic switch I58 there are three fixed contacts i iii) and Ill and three movable contacts H8, H9 and I20. The contacts H8 and H5, H9 and IIS are initially closed and the contacts Ill and I20 initially open so that movement of the thermostatic switch Iil8 will cause the two pairs of closed contacts to open and the one pair of open contacts to close. From the fixed contact IIS of the switch I08 a conductor 56 runs to the connection point on a conductor 57 which interconnects the relay switch arm 39 and the connection point 3| on the transformer secondary 22. From the main power source I9 and connected in parallel circuit with the transformer primary 2B is a conductor I2I which runs to the fixed. contact 35 of the relay switch 34. The relay switch arm 40 is connected by conductor I22 to the movable contact Ili! of the thermostatic switch I08 and a conductor I23 connects the fixed contact H of the thermostatic switch its to the connection point i2 i to which is connected the electrical resistance heater I5 which is in turn connected back to the main power source by a conductor I25. From the connection point I24 in the resistance heater a conductor i2 5 runs to the primary '!3 of an ignition transformer i l. The ignition transformer primary i3 is connected by a conductor I27 to one of the fixed contacts I28 of a thermostatic switch :29. The thermostatic switch I has two fixed contacts I28 and I and two movable contacts |3I and I32, the movable contacts being carried. by contact arm I33. The thermostatic switch I29 is actuated by a bimetallic blade I34 which operates through the insulating member I35 to move the contact arm I33. From the fixed contact I30 of the thermostatic switch I29 a conductor I36 runs to the motor 56 of the blower 1 which is connected to the main power source by a conductor I31. The contact arm I33 of the thermostatic switch I29 is connected to the main power source by a con ductor I38. On the conductor 23 from the transformer secondary 22 there is a connection point I39 from which runs a conductor I40 to the electrically controllable fuel valve I1. The fuel valve I1 is connected at a connection point I4I to a conductor I42 which leads to the fixed contact II! of the thermostatic switch I08. From the connection point MI at the fuel valve I! there is a conductor I43 which leads to the fixed contact SI of a gas tube warp switch 90. The gas tube warp switch has a bimetal blade member 89 on which is carried a movable contact 92 which cooperates with the fixed contact GI. The warp switch 98 has an ionizing electrode t3 which is connected to an induction coil 99. The bimetal contact arm 89 of the warp switch 99 is connected through its supporting member to the conductor I44 which leads to the connection point I05 where it joins the conductor I08 leading to the contact arm I0! of the thermostatic switch I08. The ignition transformer secondary S6 is connected at one end by a conductor 9'! to an ignition electrode 98. From the other end of the ignition transformer secondary 96 is connected a pair of induction coils 99 and I00 which are grounded as at IOI. The induction coil I00 is connected by a capacitance I02 to a connection point I83 on the conductor 91 leading to the ignition electrode 98.

In operation this form of the invention functions as follows:

When current is supplied from the main power source I9 the transformer 2| is energized for the control of the system. When the room thermostat 25 closes the circuit is completed from the transformer secondary 22 through the conductor 23, the

closed thermostat contacts

24 and 26, and the conductor 32 to the relay coil 33. This circuit through the relay coil 33 is completed by

conductors

42, 44, and I06, the closed contacts H6 and H9 of the thermostatic switch I08, and the conductors 56 and 51 back to the connection point 3! on the transformer secondary 22. The circuit through relay coil 33 will cause the relay switch 34 to close. Upon closing 01' the relay contacts 35 and 31 a holding circuit for the relay coil 33 is established through the

closed contacts

35 and 31 and the conductor 51 to the transformer secondary 22 which is independent of the circuit through the contacts of the thermostatic switch I08. When the relay contacts 36 and 38 are closed a circuit is com-- pleted from the main power source through the conductor I2I, the closed relay contacts 36 and 38, the conductor I22, the closed thermostatic switch contacts H5 and H8, and the conductor I275 to the electrical resistance heater I5 which is connected back to the main power source by the conductor I25. It is thus seen that when the room thermostat 25 closes calling for heat the relay switch 34 is energized and closed and a holding circuit is established therefor. With the closing of the relay switch 34 the circuit is established from the main power source through the thermostatic switch I08 for the energization of the electrical resistance heater I5 which begins to heat the hollow end portion II of the fuel vaporization member I0. The thermostatic 9 switch I29 is positioned adjacent the fuel well portion 3 and is responsive to the temperature of the hollow end portion II of the fuel vaporization member I0. When the hollow end portion II of the member I reaches sufficient temperature the thermostatic switch I29 will move closing the contacts I28 and I31, I30 and I32 respectively thus establishing a circuit from the connection point I24 of the electric heater circuit by way of the conductor I26 to the ignition primary I3 and thence by conductor I 21, the closed contacts I28 and I 3|, and conductor I38 leading back to the main power source I9. A circuit is also completed from the main power source I9 by conductor I3I to the blower motor 60 which is connected by conductor I38, the closed contacts I30 and I32, and conductor I 38 Thus it is seen that when the electrical resistance heater I5 has heated the member ill to a sufiicient temperature to close the thermostatic switch I29 circuits are established energizing the ignition transformer I4 and the blower motor 60 in preparation for the supplying of fuel to the burner. As Was described in the previous form of the invention when the ignition transformer I4 is energized and sparks occur in the spark ignition I8 the gas tube warp switch 90 is activated causing the contacts 9| and 92 to close. With the closing of the

contacts

91 and 92 of the gas tube warp switch 90 a circuit is completed from the transformer secondary 22 by way of conductors 23 and I49 to the fuel valve I"! which isin turn connected by conductor I43 to "the fixed contact 9| of the warp switch 90.

From the warp switch 90 the circuit is completed back to the transformer secondary 22 by conductors I44 and I06, the closed contacts H6 and H9 of the thermostatic switch we and conductors 55 and 51. At this point in the operation the "electrical resistance heater I5 has heated the fuel vaporization member I0 to a sufficient temperature to vaporize fuel coming in contact therewith, the spark ignition I8 is functioning causing the occurrence of sparks in the burner pot 2 and the activation of the warp switch 90 has caused the circuit to the fuel valve I! to be completed to open the same for the supply of fuel to the fuel well portion 3. When the fuel entering the fuel well portion 3 comes in contact with the vaporization member I0 it is vaporized and rises upward to the burner pot '2 where it mixes with the air supplied from the blower I and is ignited by the spark ignition I8. After ignition of the fuel vapors in the burner pot 2 the temperature of theair at the jacketed air space around the burner pot will rise above a predetermined value at which time the bimetal element II2 will cause the thermostatic switch I08 to move. Upon movement of the contact arms of the thermostatic switch I08 the contacts H6 and I I9 are opened thus breaking the ignition circuit through the relay coil 33 which is however maintained by the holding circuit heretofore described and the opening of the contacts I I5 and H8 will break the circuit through the heater coil I5 and the ignition transformer I4. When the contacts I and II"I of the thermostatic switch I08 are closed a second circuit is established for the energization of the fuel valve IT. This second fuel valve circuit runs from the transformer secondary 22 by way of conductors 23 and I40 to the valve I.'I

=and'by conductor I42, the closed contacts II! and I 20 of the thermostatic switchI'OB, the conductors I06 and 44, the closed contacts and 10 31 of the relay switch 34, and the conductor 51, the circuit terminating back at the transformer secondary 22.

In summation, it is seen that when the thermostat 25 closes calling for heat the relay switch 34 is energized and closed thereby energizing the heater coil !5. When the temperature of the fuel vaporization member I0 reaches a sufficient predetermined value the thermostatic switch I29 closes energizing the circuits through the blower motor and the ignition transformer primary I3 thereby preparing the system for the ignition of fuel. Upon the occurrence of sparks at the spark ignition IS in the burner not 2 the gas tube warp switch is activated thus completing the circuit for the energization of the fuel control valve I1 whereupon fuel is admitted to the fuel well portion 3. When the fuel admitted to the fuel well portion 3 is vaporized and ignited in the pot 2 the temperature of the jacketed air space surrounding the pot will rise causing the thermostatic switch I08 to open the contacts controlling the circuits to the heater coil I5 and the ignition transformer primary I3 thereby de-energizing the same and closing a circuit for continued energization of the fuel control valve. During combustion, as in the other form of the invention, heat for the vaporization of fuel entering the fuel Well portion 3 at the hollow end portion of the vaporization member I0 is supplied by conduction from the rod portion I 2 in the zone of combustion.

What is claimed and is desired to be obtained by Letters Patent of the United States is:

1. In a control system for a liquid fuel burner an electrically controllable valve for controlling the supply of fuel to said burner, heating means for vaporizing fuel in said burner prior to ignition thereof and including electrical heating means therefor, an electric spark ignition for said burner, means responsive to the generation of a predetermined temperature by said electrical heating means and operable to cause the energization of said ignition, means responsive to the occurrence of ignition sparks in said burner and operable to open said fuel supply control valve, means responsive to the occurrence of a predetermined temperature in said burner and operable to de-energize said ignition and said electrical heating means and to maintain said fuel supply control valve, relay switch means controlling energization of said system, a room thermostat controlling operation of said relay switch means, and said last-named responsive means including switch means opened by response to said predetermined temperature to prevent the initial energization of said relay switch means while said burner is hot.

2. In a control system for a liquid fuel burner, an electrically controllable valve for controlling the supply of fuel to said burner, a massive metallic member operable upon, heating to vaporize fuel in said burner, an electrical resistance heater for said metallic member, electrically operable air supply means for said burner, an electric spark ignition for said burner, a circuit for said ignition, a thermostatic switch in said ignition circuit operable in response to the generation of a predetermined temperature by said heater to energize said ignition circuit, means including automatic switch means responsive to the occurrence of sparks in said burner and operable to energize said electrically controllable valve for opening movement thereof, a second thermostatic switch responsive to the occurrence of a predetermined temperature in said burner and operable to denergize said ignition and said heater and to continue energization of said fuel supply control valve to hold the same open, means including a room thermostat for controlling ener gization of said system, and said last named thermostatic switch including switch contacts in series with said thermostat and operable to prevent initial energization of said system by said thermostat when the temperature in said burner is above a predetermined value.

3. A pot-type liquid fuel burner having a jacketed air space for supplying air to said burner and having a control system therefor comprising a controllable electric blower for supplying air to said jacketed air space, an electrically controllable valve for controlling the supply of fuel to the pot of said burner, a massive metallic member positioned in the pot of said burner and operable upon heating to vaporize fuel conducted thereagainst, an electrical resistance heater for said metallic member, an electric spark ignition for said burner, circuits for said ignition and said blower, a thermostatic switch closable in response to the generation of a predetermined temperature by said heater to energize said ignition and said blower circuits, means including automatic switch means responsive to the occurrence of ignition sparks in said burner and operable to energize said electrically control-- lable valve for opening movement thereof, a second thermostatic switch positioned in said jacketed air space and responsive to the occur rence of a predetermined temperature in said burner and operable to deenergize said ignition and said heater and to continue energization of said fuel supply control valve to hold the same open, means including a room thermostat for controlling energization of said system, and said last named thermostatic switch including switch contacts in series with said thermostat and operable to prevent initial energization of said system by said thermostat when the temperature in said burner is above a predetermined value.

4. A control system for a liquid fuel burner having a jacketed air space for supplying air to said burner comprising a burner pot having a fuel well portion, a controllable electric blower for supplying air to said jacketed air space, an electrically controllable valve for controlling the supply of fuel to said fuel well portion, a massive metallic member positioned in said fuel well portion and extending upward through said pot and operable upon heating to vaporize fuel supplied to said fuel well portion, an electrical resistance heater for said metallic member, an electric spark ignition for said burner, circuits for said ignition and said blower, a thermostatic switch positioned adjacent said fuel well portion and closable in response to the generation of a predetermined temperature by said heater to energize said ignition and said blower circuits, means including an automatic switch responsive to. the occurrence of electrical ignition sparks in said burner and operable to energize said electrically controllable valve for opening movement thereof, a second thermostatic switch positioned in said jacketed air space and responsive to the occur rence of a predetermined temperature in said burner and operable to de-energize said ignition and said heater and to continue energization of said fuel supply control valve to hold the same open, relay switch means controlling energizetion of said system, a room thermostat controlling energization of said relay switch means,

and said last-named thermostatic switch including switch contacts in series with said room thermostat and operable to prevent initial energization of said relay switch means while the temperature of said burner is above said predetermined temperature.

5. A control system for a liquid fuel burner comprising a burner pot having a fuel well portion, a constantly running electric blower for supplying air to said pot, an electrically controllable valve for controlling the supply of fuel to said fuel well portion, a massive metallic member positioned in said fuel well portion and extending upward through said pot, an electrical resistance heater for said metallic member, said metallic member being heated initially by said heater and subsequently by flame in said pot and being operable upon said heating to vaporize fuel in said fuel well portion, an electric spark ignition for said burner, an electric circuit for said ignition, a thermostatic switch positioned adjacent said fuel well portion and closable in response to the generation of a predetermined temperature by said heater to energize said ignition, circuit means including automatic switch means responsive to the occurrence of electrical ignition sparks in said burner and operable to energize said electrically controllable valve for opening movement thereof, a second thermostatic switch positioned adjacent said fuel well portion and responsive to the temperature of said metallic member when heated by the occurrence of flame in said pot and operable to deenergize said ignition and said heater and to continue energization of said fuel supply control valve to hold the same open, relay switch means controlling energization of said system, a room thermostat controlling energization of said relay switch means, and said last named thermostatic switch including switch contacts in series with said room thermostat and controlling energization of said relay switch means.

6. In a liquid fuel burner and control system therefor, a vaporizing pot, electrically controlled means for supplying fuel to said pot, a metallic member positioned in said pot and extending upward into the zone of combustion and operable upon heating to vaporize fuel entering said pot, electrical means operable upon energization to heat said metallic member for initial operation, said metallic member being subsequently heated by flame after the occurrence of the same in said pot, means responsive to the heat of flame in said pot and operable to de-energize said electrical heating means, means including a room thermostat for controlling energization of said system, and said last-named responsive means including switch means connected in series with said thermostat and operable to prevent initial energization of said system by said thermostat so that said fuel supply means may not be energized while the temperature of said burner pot is in excess of a predetermined value.

'7. A liquid fuel burner having a. vaporizing pot, a fuel well opening upwardly into said pot, a metallic member having an enlarged hollow end portion and a solid rod end portion for conducting heat to said hollow end portion, said enlarged hollow end portion being positioned in said fuel well and forming with the walls of said fuel well an annular space of small cross section, said solid rod end portion extending upwardly through said pot into the zone of combustion, said metallic member being operable upon heating to vaporize fuel in said annular space, an

electrical resistance heater in said hollow end portion and operable upon energization to heat the same for initial operation, said hollow end portion being heated by conduction of heat from said solid rod portion after the occurrence of combustion in said pot, means responsive to the heat of combustion in said pot and operable to de-energize said electrical resistance heater, an electrically operated valve controlling the supply of fuel to said burner, electric circuit means for controlling said valve, means including a room thermostat controlling energization of said electric circuit means, and said responsive means including switch means connected in series with said room thermostat and operable to prevent initial energization of said electric circuit means by said room thermostat when the temperature of said burner pot is in excess of a predetermined value.

8. In a control system for a liquid fuel burner, electrically operated means for controlling the supply of fuel to said burner, a fuel vaporizing member having an electric heating coil and operable to vaporize fuel prior to ignition thereof, an electric spark ignition in said burner and having an energizing transformer; electric circuits for said fuel supply means, said electric heating coil, and said transformer; a thermostatic switch in said transformer circuit and operable to energize said ignition in response to heat of said heating coil, means in said fuel supply circuit responsive to the occurrence of sparks in said burner and operable to actuate said fuel supply means, a single pole double throw switch having a pair of initially closed contacts in a portion common to said ignition transformer circuit and said heating coil circuit, a second circuit for said fuel supply means independent of said spark responsive means, said last-named switch having a pair of initially open contacts in said second fuel supply circuit; thermostatic means responsive to the heat of combustion in said burner and operable to move said last-named switch to deenergize said ignition and said heating coil circuits, and to energize said second fuel supply means circuit; a relay switch having a pair of initially open contacts in series with the movable pole of said last-named switch, an energizing circuit for the coil of said relay switch, a room thermostat in said relay coil circuit, an initially closed switch in said relay coil energizing circuit and operated by said combustion responsive thermostatic means, and circuit means including a switch closed upon energization of said relay coil to shunt said last named switch.

9. In a control system for a liquid fuel burner, means for controlling the supply of fuel to said burner, means for vaporizing fuel in said burner prior to ignition thereof and including electrical energization means therefor, electrical means for igniting fuel in said burner, means responsive to the heating of said fuel vaporization means and operable to control the energization of said fuel supply controlling means, means responsive to the heat output of said burner and operable to de-energize said ignition means and said fuel vaporization means, a relay switch having a coil and circuit therefor and having contacts controlling energization of said system, a room thermostat controlling energization of said relay coil, switch means in said relay coil circuit and opened by said last-named responsive means to prevent initial energization of said system by operation of said thermostat while said burner is above a predetermined temperature, and said relay switch having contacts connected in parallel with said last named switch means to provide a holding circuit for said relay coil during normal operation of said burner.

FRED B. AU'BERT.

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