US3276507A - Burner control system - Google Patents

Burner control system Download PDF

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Publication number
US3276507A
US3276507A US429480A US42948065A US3276507A US 3276507 A US3276507 A US 3276507A US 429480 A US429480 A US 429480A US 42948065 A US42948065 A US 42948065A US 3276507 A US3276507 A US 3276507A
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US
United States
Prior art keywords
burner
scr
relay
winding
lead
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US429480A
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English (en)
Inventor
Jr Raymond W Eldridge
Robert C Krump
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Emerson Electric Co
Original Assignee
Emerson Electric Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Emerson Electric Co filed Critical Emerson Electric Co
Priority to US429480A priority Critical patent/US3276507A/en
Priority to GB1535/66A priority patent/GB1079085A/en
Priority to NL6601111A priority patent/NL6601111A/xx
Priority to BE675782D priority patent/BE675782A/xx
Application granted granted Critical
Publication of US3276507A publication Critical patent/US3276507A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/20—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays
    • F23N5/203—Systems for controlling combustion with a time programme acting through electrical means, e.g. using time-delay relays using electronic means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23N—REGULATING OR CONTROLLING COMBUSTION
    • F23N5/00—Systems for controlling combustion
    • F23N5/02—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium
    • F23N5/08—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using light-sensitive elements
    • F23N5/082—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using light-sensitive elements using electronic means

Definitions

  • This invention relates to automatic control systems for fluid fuel burners which include-des safety means operative to permit the supply of fuel to the burner when there is combustion flame and to cut olf such supply in event cornbustion fla-me is not established or having been estab-lished is extinguished, and which safety means includes a photoconductive device and a solid state switching device.
  • the primary object of the invention is to provide a generally new and improved safety control system for fluid fuel burners incorporating instantly responsive, combustion lia-me detecting means and solid state switching means in a novel arrangement which provides -a particularly simple, economical, and reliable construction.
  • the single ligure of the drawing is a diagrammatic illustration of a control system for a conventional, pressure-type oil burner.
  • the primary elements of the system include an oil burner having a driving motor 12, a space thermostat 14, a motor relay having a winding 16 with two sets of normally open contacts 18 and 20, a normally closed thermal time switch 22 (safety switch) including an electrical resistance heater 24, a light sensitive element 26, a silicon-controlled rectifier 28 (SCR) having a control electrode 25 and a control network comprising the light sensitive cell 26, a control resistor 30 with sliding contact 32, and a xed major voltage dropping resistor 34, a spark igniter comprising electrodes 36 and a step-up transformer 38, a voltage step-down, power supply transformer 40 having a primary winding 44 and a secondary winding 42, and a pair of power supply leads 46 for connection to a suitable source of A.C. power.
  • a normally closed thermal time switch 22 safety switch
  • safety switch including an electrical resistance heater 24, a light sensitive element 26, a silicon-controlled rectifier 28 (SCR) having a control electrode 25 and a control network comprising the light sensitive cell 26, a control resistor 30
  • the oil burner 10 includes the usual blower and fuel pump which, when driven by motor 12, supply atomized oil and combustion air to the burner nozzle where it is ignited by arcing across spark electrodes 36.
  • the motor 12 and igniter transformer 38 are connected in parallel across the' power supply leads 46 and through normally open motor relay contacts 18, when closed, by leads 48, 50, 52, 54, and 56. The motor 12 and igniter 38 a-re therefore energized simultaneously when relay contacts 18 are closed.
  • the light sensitive element 26 is of the semiconductor type having an extremely high electrical resistance in the absence of light and becoming considerably less resistive when impinged by the light of burner flame.
  • the positioning of light sensitive element 26 so as to be responsive to burner ame and yet be shielded from ambient light is preferably that shown and ldescribed in United States Letters Patent, No. 3,079,982, issued March 15, 1963, to Bernardus J. Staring.
  • the resistors 30 and 34 are series connected across the SCR 28, and the SCR control electrode 25 is connected to the left side of transformer secondary winding 42 through a lead 74, a lead 76, and slider contact 32, a portion of the control resistor 30, the major voltage dropping resistor 34, a lead 60, thermostat 14, and a lead 58.
  • the light sensitive cell 26 and a portion of control resistor 30 are connected in parallel between the SCR control electrode 25 and the cathode side of the SCR by the lead 74 and by lead 76 and slider 32 and by leads 78, 80, and 82.
  • the resistance between the SCR control electrode 25 and the left side of transformer secondary 42 due to resistor 34 and a portion of resistor 30 is such that suiicient or just slightly more than sufficient voltage is applied to the SCR control electrode during the 4conductive half cycle of the SCR and upon closure of thermostat 1-4 to effect conduction of the SCR under conditions of no flame ⁇ at the burner 10 when the resistance of light sensitive element 26 is very high.
  • the resistance of element 26 decreases and the voltage drop thereacross which then occurs is such that the voltage applied to the SCR control electrode falls below that which will effect conduction of the SCR.
  • the motor relay winding 16 is also connected ⁇ across a lefthand portion A of the transformer secondary winding 42 by a circuit branch extending from a point B at the junction of leads 60-62 and comprising the lead ⁇ 62, the safety switch 22, lead 64, motor relay Winding 16, lead 66, a lead 84, relay contacts 20, and a lead 86 connected to the transformer secondary winding 42 at an intermediate point therealong.
  • the motor relay winding 16 and secondary winding 42 are so constructed, and the connection of lead 86 with winding 42 is so positioned therealong, that the half wave energization of relay winding 16 as effected by its connection across the entire secondary winding 42 through SCR 28 is sufficient to effect the closing of relay contacts 18 and 20, while, on the other hand, the full wave, A.C. energization of winding 16 as effected by its connection across the portion A of transformer secondary 42 is insuicient to cause the operation of the relay from open to closed contact position, but is sufficient to hold the relay in closed contact position once it is in closed contact position.
  • thermostat 14 Under normal operating conditions, the closure of thermostat 14 upon call for burner operation effects halfwave energization of relay winding 16 through safety switch 22, safety switch heater 24, and SCR 28 across the entire secondary winding 42 to cause the closing of contacts 18 and 20.
  • the resistance of light sensitive element 26 under these conditions of no flame is very high, and a firing signal is therefore applied to SCR 28 each conducing half cycle.
  • the closing of relay contacts 18 completes the circuit across power supply leads 46 thereby energizing burner motor 12 and igniter 38, whereupon fuel and air are supplied to the burner and ignited.
  • the closing of relay contacts 20 completes the circuit branch connecting the relay winding 16 through the safety switch 22 (but not through the safety switch heater 24) across the lefthand portion A of transformer secondary winding 42.
  • the safety switch heater 24 will warp the bimetal contact blade of the safety switch 22 ⁇ and effect opening of the safety switch contacts, thereby breaking both the circuit connecting relay winding 16 across the entire secondary winding 42 and the branch circuit connecting it across the portion A of secondary winding 42. Under these conditions operation of the burner and igniter are cut olf, as Well as energization of the safety ⁇ switch heater 24 land conduction through SCR 28.
  • a spring latching device 88 is provided which is operative to retain safety switch 22 in an open position when it is warped open so that manual resetting of the safety switch is required to kre-start the system.
  • the safety switch will open, the safety switch heater 24 being in series with the SCR 28. If SCR 28 malfunctions in a manner so as to fail to conduct when it should, or if light sensitive element 26 malfunctions or is inadvertently exposed to ambient light so as to prevent the application of a signal voltage to the SCR gate, the system will fail safely inasmuch as, under these conditions, relay winding 16 will not be energized suflciently to close contacts 18-20.
  • the relay winding 16 will be required to be energized through the safety switch heater 24 upon recurrence of the power supply, in order to again close contacts 18-20, so that continued operation of the burner motor is always contingent upon successful ignition within the predetermined trial period.
  • the purpose of the slider contact 32 on control resistor 30 is to permit optimum calibration of the SCR gate network for light conditions of the particular installation and to compensate for variations in the Iresistivity of light sensitive element 26.
  • the power supply voltage step-down transformer 40 may be dispensed with if a lower voltage than the available power supply is not required or desired.
  • the leads 58 and 72 are connected to the respectively adjacent leads 46, and the branch circuit lead 86 is connected tothe righthand lead 46 through a. suitable impedance.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Regulation And Control Of Combustion (AREA)
  • Control Of Combustion (AREA)
US429480A 1965-02-01 1965-02-01 Burner control system Expired - Lifetime US3276507A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US429480A US3276507A (en) 1965-02-01 1965-02-01 Burner control system
GB1535/66A GB1079085A (en) 1965-02-01 1966-01-12 Burner control system
NL6601111A NL6601111A (enrdf_load_html_response) 1965-02-01 1966-01-28
BE675782D BE675782A (enrdf_load_html_response) 1965-02-01 1966-01-31

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US429480A US3276507A (en) 1965-02-01 1965-02-01 Burner control system

Publications (1)

Publication Number Publication Date
US3276507A true US3276507A (en) 1966-10-04

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ID=23703438

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Application Number Title Priority Date Filing Date
US429480A Expired - Lifetime US3276507A (en) 1965-02-01 1965-02-01 Burner control system

Country Status (4)

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US (1) US3276507A (enrdf_load_html_response)
BE (1) BE675782A (enrdf_load_html_response)
GB (1) GB1079085A (enrdf_load_html_response)
NL (1) NL6601111A (enrdf_load_html_response)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3335781A (en) * 1966-04-11 1967-08-15 Emerson Electric Co Burner control system
US3364972A (en) * 1966-01-17 1968-01-23 Itt Combustion control system
US3367387A (en) * 1965-04-13 1968-02-06 Hitachi Ltd Combustion control device for fuel burners
US3380796A (en) * 1967-02-03 1968-04-30 Honeywell Inc Fuel burner control apparatus
US3393039A (en) * 1966-05-11 1968-07-16 Emerson Electric Co Burner control system
US3453063A (en) * 1967-10-05 1969-07-01 Penn Controls Fluid fuel burner control utilizing slaved silicon controlled rectifiers
US3480374A (en) * 1967-07-07 1969-11-25 Tappan Co The Spark ignition system
US3488132A (en) * 1967-12-28 1970-01-06 Controls Co Of America Ignition and fuel control circuit

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2080580A (en) * 1935-12-02 1937-05-18 Penn Electric Switch Company Burner control circuit protection system
US2086823A (en) * 1936-08-03 1937-07-13 Penn Electric Switch Co Control system for fuel burners
US3086147A (en) * 1960-06-06 1963-04-16 Penn Controls Flame detector circuit
US3174528A (en) * 1965-03-23 Staring burner control system

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3174528A (en) * 1965-03-23 Staring burner control system
US2080580A (en) * 1935-12-02 1937-05-18 Penn Electric Switch Company Burner control circuit protection system
US2086823A (en) * 1936-08-03 1937-07-13 Penn Electric Switch Co Control system for fuel burners
US3086147A (en) * 1960-06-06 1963-04-16 Penn Controls Flame detector circuit

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3367387A (en) * 1965-04-13 1968-02-06 Hitachi Ltd Combustion control device for fuel burners
US3364972A (en) * 1966-01-17 1968-01-23 Itt Combustion control system
US3335781A (en) * 1966-04-11 1967-08-15 Emerson Electric Co Burner control system
US3393039A (en) * 1966-05-11 1968-07-16 Emerson Electric Co Burner control system
US3380796A (en) * 1967-02-03 1968-04-30 Honeywell Inc Fuel burner control apparatus
US3480374A (en) * 1967-07-07 1969-11-25 Tappan Co The Spark ignition system
US3453063A (en) * 1967-10-05 1969-07-01 Penn Controls Fluid fuel burner control utilizing slaved silicon controlled rectifiers
US3488132A (en) * 1967-12-28 1970-01-06 Controls Co Of America Ignition and fuel control circuit

Also Published As

Publication number Publication date
BE675782A (enrdf_load_html_response) 1966-08-01
GB1079085A (en) 1967-08-09
NL6601111A (enrdf_load_html_response) 1966-08-02

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