US3663150A - Safety ignition control system - Google Patents

Safety ignition control system Download PDF

Info

Publication number
US3663150A
US3663150A US5439A US3663150DA US3663150A US 3663150 A US3663150 A US 3663150A US 5439 A US5439 A US 5439A US 3663150D A US3663150D A US 3663150DA US 3663150 A US3663150 A US 3663150A
Authority
US
United States
Prior art keywords
ignition
resistance
fuel
current
combustion
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
US5439A
Other languages
English (en)
Inventor
William H Hapgood
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.)
Raytheon Co
Original Assignee
Raytheon 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 Raytheon Co filed Critical Raytheon Co
Application granted granted Critical
Publication of US3663150A publication Critical patent/US3663150A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23Q—IGNITION; EXTINGUISHING-DEVICES
    • F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
    • F23Q7/22—Details
    • F23Q7/24—Safety arrangements
    • 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
    • F23N5/14—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermo-sensitive resistors
    • 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
    • F23N5/14—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermo-sensitive resistors
    • F23N5/146—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermo-sensitive resistors using electrical or electromechanical means
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23Q—IGNITION; EXTINGUISHING-DEVICES
    • F23Q1/00—Mechanical igniters
    • F23Q1/02—Mechanical igniters using friction or shock effects
    • F23Q1/06—Portable igniters
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
    • F23Q—IGNITION; EXTINGUISHING-DEVICES
    • F23Q7/00—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs
    • F23Q7/06—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs structurally associated with fluid-fuel burners
    • F23Q7/10—Incandescent ignition; Igniters using electrically-produced heat, e.g. lighters for cigarettes; Electrically-heated glowing plugs structurally associated with fluid-fuel burners for gaseous fuel, e.g. in welding appliances

Definitions

  • ABSTRACT A control system for use in combination with any combustion Related Apphcafion new type heating device to provide a fail-safe safety ignition [63] Continuation-impart f S N 772,559, N 1 system.
  • Cl ..43l/66 P coefficient of electrical resistance are l 511 1111.0 ..F2311 5/14 in the Symm- The Current due to varying resistance of the [58] Field of Search ..43 1/75, 78, 66 Sensing means will develop from a high initial value to a lower average normal running current value upon satisfactory igni- 56] References Cited tion.
  • the system parameters are selected to automatically disconnect the fuel source in the event of a failure in the com- UNITED STATES PATENTS bustion cycle.
  • the circuit which includes the sensing means may also include a temperature indicating device.
  • a system for a simple, reliable and inexpensive fail-safe control system for thermally and electrically performing the flame sensing function in combustion type heating apparatus.
  • the system also incorporates appropriate flame igniting means.
  • the sensing means comprising an element having a high positive temperature coefficient of electrical resistance is combined with circuit interruption means and fuel supply disconnect means to provide the fail-safe system.
  • the material selected for the sensing preferably is molybdenum disilicide.
  • the resistivity of the sensing element at room temperature is low.
  • the resistance is substantially higher by a factor of approximately three to one to provide for substantially reduced current values.
  • Appropriate selection of the parameters of the sensing member will desirably provide a drop in current of approximately one-half to an average running current value when satisfactory combustion occurs and the sensing member temperature rises.
  • a circuit interruption means such as a circuit breaker having a predetermined minimum threshold value intermediate to the high initial current value and average normal running current values is interconnected with the fuel supply source and the sensing means. This circuit will provide for automatically disconnecting the fuel supply after a predetermined period of ignition failure by reason of the current value exceeding the predetermined circuit breaker minimum threshold value.
  • the igniter comprises an element of the same material as the sensor and may be connected in series with it or may be independently connected to a voltage source. Since the current through the sensor varies substantially with the temperature within the apparatus, the value of that current may be used to measure such temperature by connecting a current meter, calibrated to indicate temperature, in series with the sensor.
  • the safety ignition control system of the invention is substantially less expensive than prior art devices for similar purposes, without any sacrifice of its fail-safe properties.
  • the electrical circuit of the disclosed system is equally applicable to any type fuel source and all combustion type devices.
  • FIG. 1 is a vertical cross-sectional view of an illustrative combustion type device incorporating the structure of the present invention
  • FIG. 2 is an enlarged perspective view partially in section of an alternative embodiment of the sensor and igniter structure
  • FIG. 3 is a schematic circuit diagram of an illustrative embodiment of a system according to the present invention.
  • FIG. 4 is a graph of current versus time explaining the operation of the present invention.
  • FIG. 5 is a graph of the electrical resistivity versus temperature characteristics of a material for the sensing means.
  • FIG. 6 is a circuit diagram for the modification represented by FIG. 2.
  • FIG. 1 illustrates an exemplary embodiment of a combustion type heat exchanger device 10 for the heating of circulating fluids.
  • a helical conduit 11 is provided with an inlet connector 12 and an outlet connector 13 coupled to any conventional fluid source and utilization means.
  • the conduit structure is embedded in a matrix structure l4 composed of a plurality of discrete thermally conductive bodies suitably joined together by metallurgical processes to provide a self-supporting structure.
  • a central combustion chamber 15 is thus defined by the disclosed heat exchange device.
  • a top plate member 22 is suitably secured to the matrix structure 14 by nut and bolt means 23 to enclose one end of the combustion chamber.
  • a lower support plate member 16 has secured thereto a closure member 17 which has appended thereto and centrally positioned within the combustion chamber a multi-ported burner assembly 18.
  • the fuel for the burner assembly may be provided in the form of an air-gas mixture underpressure from a source coupled to conduit 19 suitably secured to the end closure member 17.
  • An outer wall enclosure member 20 surrounds the combustion heater and provides for the egress of the exhaust gases passing through the sintered matrix.
  • a vent 21 extends laterally from the outer wall member 20 and may be coupled to any convenient outlet for the egress of the combustion gases.
  • the sensing means 36 and ignition means 37 may comprise members of varying dimensions of a resistance material to be hereinafter specified.
  • the members are individually mounted on a ceramic base member 31 suitably secured to the end closure 17 so as to be exposed to the interior of combustion chamber 15.
  • the member 36 is provided with external connecting leads 32 and 34 and the member 37 is provided with external connecting leads 33 and 35.
  • the ignition and sensing means have been indicated in a unitary supporting structure it is well within the precepts of the invention to provide separate ignition and sensing members in any desired position within the combustion device.
  • the longer loop member 36 of larger cross-sectional area is utilized for performing of the sensing function and the shorter somewhat thinner loop member 37 serves as the igniter.
  • the electrical resistivity versus temperature parameter of the preferred material will now be enumerated.
  • the principal determining feature is that at low temperatures, illustratively from room temperature to for example l,000 F., a very low resistivity is provided with resultant high currents.
  • the resistivity rises sharply to yield much lower currents.
  • the normal operating temperature range is indicated by the dotted line 38 or 1,000 F. for the lower end and dotted line 39 for the high end of 2,500 F. From the slope of the curve 40 it will be noted that the resistivity parameter increases by a factor of substantially 3:1 from a value of 100 microhms per centimeter.
  • a material exemplary of the desired characteristics is a composition of a minimum of percent molybdenum disilicide with approximately 10 percent of metallic and ceramic binder additions to provide an electrical resistance element.
  • a material is available as Kanthal Super" and provides the wide span of desired electrical resistivity parameters over the temperature range.
  • the length and cross-sectional area of the respective sensing and ignition members of the applicable material are preferably selected in connection with the control circuit of the invention now to be described.
  • FIG. 3 a schematic of an electrical control circuit is shown having a source of electrical potential coupled by means of terminals 41 and 42 to a low voltage transformer 43 to provide, illustratively, volts which may be either direct or alternating current. In the case of direct current, an appropriate rectifier would be used to convert the alternating current to direct current.
  • the applicable combustion type device is indicated generally by the numeral 44 and may be of the heat transfer module type described above.
  • a solenoid 46 under the control of the sensor member 36 is used to control a fuel supply valve 47.
  • the igniter member 37 may be connected directly across the secondary of the transformer 43.
  • the control circuit further incorporates a circuit breaker 45 to provide for circuit interruption in the event that an abnormal current condition prevails after a predetermined time delay.
  • a standard circuit breaker which may be used in this circuit is one which includes a heater 54 and switch contacts 55 in series with the solenoid 46 and the sensor member 36, the switch contacts 55 being adapted to open if and when the heating effect of the heater 54 exceeds a predetermined value.
  • the igniter loop 37 is designed to pass a relatively large initial surge of current, which may be, for example, 10 amperes. Thereupon, the igniter loop will immediately glow so as to provide ignition energy to fuel supplied through the fuel valve 47. During the ignition cycle the current may drop to approximately 5 amperes, while maintaining the igniter loop at proper igniting temperature.
  • the sensor loop 36 Upon energization of transformer 43, the sensor loop 36 is also designed to pass a relatively large initial surge of current which prior to actual ignition may stabilize at a value of about 5 amperes. This large surge supplied to the solenoid 46 assures that the solenoid will open the fuel valve 47 to supply fuel to the burner 18.
  • the sensor loop 36 is designed to be longer and thicker than the igniter loop 37 and, therefore, its temperature is not raised to the extent which occurs in the igniter loop 37, but rather remains at a comparatively low level until raised by the heat generated by the burning fuel. As a result, the resistance of the sensor loop 37 remains low until such burning takes place. Upon ignition the heat from the burning fuel will elevate the temperature of the sensor loop member at the high or 2,500 F.
  • the fuel valve actuator 46 in the exemplary circuit is selected to have a pull-in current value of about 5 amperes.
  • the drop-out current value will desirably be less than 2% amperes or the average normal running current value as an additional safety feature.
  • the circuit breaker with the aforementioned 10 second delay will have, illustratively, a predetermined threshold value intermediate to the average normal.
  • the operation is diagrammatically illustrated with the initial cold current surge indicated by the portion 48 of the current versus time curve.
  • start point 49 which in the illustrative embodiment was 5 amperes
  • ignition within the combustion chamber will result by reason of the glowing of the igniter loop member 37.
  • Successful ignition will result in a current drop to a value indicated by the portion 50 of the curve of approximately one-half the initial value or 2% amperes.
  • This latter portion represents the average normal running current in a normalized control circuit after ignition and the heating of the sensor loop member 36 to the high resistivity parameter.
  • the circuit breaker which is set to break the circuit at illustratively 3 amperes, as indicated by the dotted line 52, will automatically function.
  • the breaking of the circuit by reason of the continued high initial current will disconnect the fuel source from the combustion device 44.
  • the drop-out current value for the solenoid 46 is indicated by dotted line 53 at less than 2% amperes.
  • any other appropriate type of igniter may be used, such as, for example, a spark igniter.
  • the igniter loop of the same type of material as the sensor loop there two elements may be combined in an arrangement as shown in FIGS. 2 and 6.
  • FIG. 2 the loops 36 and 37 are connected in series internally within the base 81 and the combined structure is provided with only two external leads 32 and 33.
  • the series combined sensor-ignitor, as shown in FIG. 6, is substituted for the sensor-ignitor of FIG. 3 and the separate circuit for the igniter loop 37 in FIG. 3 is omitted.
  • the length and thickness dimensions of the loop 36 are so much greater than those of loop 36 that during the preignition period, the loop 36 remains at a comparatively low temperature, while the loop 37 is heated to ignition temperature.
  • the length and thickness dimensions of loop 36 may each be double those of loop 36. Under such conditions, the influence of the loop 37 will predominate for ignition while that of the loop 36 will predominate to control the circuit breaker 45.
  • the advantage of the preferred embodiment of FIGS. 1 and 3 is that the ignition loop 37 is always energized to supply ignition energy, even when the circuit breaker has opened.
  • the positioning of the sensing and igniter means will vary.
  • the predetermined drop in the average normal running current upon the heating of the sensor loop member is the determining parameter in the selection of the respective dimensions of the electrical resistance elements having the desired positive coefficient of resistivity versus temperature properties.
  • the sensor loop member dimensions will be a multiple of the igniter member length determined by the average normal running current.
  • the primary feature is that the resistance valve be sufficiently high at the combustion temperature to make the circuit operative and the parameters of the circuit breaker means as well as the fuel supply control means will be accordingly determined.
  • a working parameter in the design of such circuits may be the one-half current valve described herein for the minimum running current.
  • a combustion control system comprising a. a burner
  • a resistance member comprising a material having a high positive temperature coefficient of electrical resistance disposed to be heated by the combustion of said fuel in said burner whereby said resistance of said member is substantially changed when heated by the combustion of said fuel for a predetermined time;
  • control means responsive to the magnitude of current flow through said resistance member for shutting ofi the supply of fuel from said supply means to said burner a predetermined time after said fuel is first supplied to said burner during which there is no combustion in said burner.
  • a system as specified in claim 1 in which a. there is provided ignition means for supplying ignition energy to the supplied fuel during an ignition period, and
  • said control means is responsive to the persistence of the magnitude of said resistance at a value below a predetermined value for a predetermined period of timeafter the beginning of said ignition period.
  • a combustion control system comprising:
  • a resistance member comprising a material having a high positive temperature coefficient of electrical resistance disposed to be heated by the combustion of said fuel in said burner;
  • time delay control means responsive to the magnitude of the resistance of said resistance member for controlling the supply of fuel through said supply means, comprising ignition means for supplying ignition energy to the supplied fuel during an ignition period, said control means being responsive to the persistence of the magnitude of said resistance at a value below a predetermined period of time after the beginning of said ignition period, a time delay relay having a current responsive device in series with a source of voltage and said resistance member, said current responsive device being operative to open a pair of contacts when a current above a predetermined value has passed through said current responsive device for a predetermined time, and a fuel control valve operable by a current responsive device in series with said contacts and a voltage source.
  • a means for ignition and sensing of combustion within said apparatus comprising:
  • serially connected members disposed in communication with the region of combustion within said apparatus;
  • one of said members being dimensioned to provide a low electrical resistivity at the low temperature end of the operating range of the apparatus and serving as the igniter means;
  • an electrical control circuit interconnecting said fuel source and said ignition and sensing means to disconnect said fuel source a predetermined period of time after connection of said fuel source in the event of failure of said sensing means to achieve a predetermined high temperature and high electrical resistivity characteristics during said predetermined period of time with a resultant high current in the circuit in excess of a threshold value.
  • said resistance material comprises principally molybdenum disilicide.
  • a means for ignition and sensing of combustion within said apparatus comprising:
  • serially connected members of a resistance material having a high positive temperature coefiicient of electrical resistance disposed in communication with the region of combustion within said apparatus;
  • one of said members being dimensioned to provide a low electrical resistivity at the low temperature end of the operating range of the apparatus and serving as the igniter means;
  • the other of said members being dimensioned to provide a high electrical resistivity at the high temperature end of the operating range of the apparatus and serving as the sensing means;
  • an electrical time delay control circuit interconnected with the fuel source and said ignition and sensing means to disconnect said fuel source in the event of failure of said sensing means to achieve a predetermined high temperature and high electrical resistivity characteristics after a predetermined period of time with a resultant high current in the circuit in excess of a threshold value;
  • said circuit having an initial high current value resulting in ignition of combustion and a lower average normal running current value resulting from heating of the sensing means by the said electrical control circuit;
  • said circuit interruption means having a threshold value to break the circuit should such a current value be prevalent after a predetermined period of time.
  • a safety ignition control system for combustion type heating apparatus having a source of fuel comprising:
  • said ignition member being of a reduced cross-sectional area and length relative to said sensing member to provide for a low resistance to current at the low temperature end of the operating range of the apparatus;
  • an electrical time delay control circuit interconnecting said igniter and sensing members and said fuel source including:
  • circuit interruption means having a predetermined minimum current threshold value
  • electrically actuated means to disconnect said fuel source; positive temperature coefficient of electrical resistance said circuit having an initial high current value passing so1edisposed to be subjected to an ambient temperature;
  • said circuit further having a lower average normal running c. means responsive to the magnitude of the resistance of current value determined by the heating of the Sensing said resistance member for discontinuing said current member by the generated combustion heat;
  • circuit interruption means being adapted to break the circuit upon failure of combustion and continuance of the circuit current value above the minimum threshold value 10 for a predetermined period of time.
  • a safety ignition control system according to claim 10, wherein the cross-sectional area and length of said ignition member are approximately one-half of the sensing member similar dimensions.
  • a temperature responsive device comprising:
  • a resistance member comprising a material having a high through said resistance member a predetermined time after said current is first supplied to said resistance member.
  • a device as specified in claim 13 in which said temperature indicating means comprises a current responsive device in series with said resistance member and a source of voltage.

Landscapes

  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Combustion (AREA)
  • Regulation And Control Of Combustion (AREA)
US5439A 1970-01-23 1970-01-23 Safety ignition control system Expired - Lifetime US3663150A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US543970A 1970-01-23 1970-01-23

Publications (1)

Publication Number Publication Date
US3663150A true US3663150A (en) 1972-05-16

Family

ID=21715870

Family Applications (1)

Application Number Title Priority Date Filing Date
US5439A Expired - Lifetime US3663150A (en) 1970-01-23 1970-01-23 Safety ignition control system

Country Status (8)

Country Link
US (1) US3663150A (fr)
JP (1) JPS496843B1 (fr)
BE (1) BE761446A (fr)
CH (1) CH524787A (fr)
FR (1) FR2075280A5 (fr)
GB (1) GB1330800A (fr)
IE (1) IE35354B1 (fr)
NL (1) NL7016752A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4171772A (en) * 1972-11-16 1979-10-23 Amana Refrigeration, Inc. Package heat exchanger system for heating and cooling
US5240406A (en) * 1990-12-28 1993-08-31 Ichiro Kanesaka Gas heater
US5617721A (en) * 1995-08-14 1997-04-08 General Motors Corporation Exhaust catalyst preheater with flame igniter and sensor element
US5704775A (en) * 1996-03-28 1998-01-06 Gilbert; Paul A. Auxiliary igniter and control for a furnace

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3393038A (en) * 1965-11-08 1968-07-16 Texas Instruments Inc Ignition systems
US3445172A (en) * 1967-08-02 1969-05-20 American Gas Ass Fail-safe system
US3488133A (en) * 1969-01-09 1970-01-06 Tappan Co The Protected hot wire ignition system

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3393038A (en) * 1965-11-08 1968-07-16 Texas Instruments Inc Ignition systems
US3445172A (en) * 1967-08-02 1969-05-20 American Gas Ass Fail-safe system
US3488133A (en) * 1969-01-09 1970-01-06 Tappan Co The Protected hot wire ignition system

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4171772A (en) * 1972-11-16 1979-10-23 Amana Refrigeration, Inc. Package heat exchanger system for heating and cooling
US5240406A (en) * 1990-12-28 1993-08-31 Ichiro Kanesaka Gas heater
US5617721A (en) * 1995-08-14 1997-04-08 General Motors Corporation Exhaust catalyst preheater with flame igniter and sensor element
US5704775A (en) * 1996-03-28 1998-01-06 Gilbert; Paul A. Auxiliary igniter and control for a furnace

Also Published As

Publication number Publication date
IE35354B1 (en) 1976-01-21
NL7016752A (fr) 1971-07-27
CH524787A (de) 1972-06-30
FR2075280A5 (fr) 1971-10-08
DE2102835A1 (de) 1971-09-16
BE761446A (fr) 1971-06-16
DE2102835B2 (de) 1973-02-01
JPS496843B1 (fr) 1974-02-16
GB1330800A (en) 1973-09-19

Similar Documents

Publication Publication Date Title
US4638789A (en) Safety apparatus for combustion device
US4125357A (en) Control and monitoring system for gas burners
US2327690A (en) Control apparatus
CA1180789A (fr) Commande d'excitation pour fil incandescent d'allumage du gaz
US4325689A (en) Automatic reset control for direct spark ignition systems
US3488131A (en) Electronic spark ignitor control for fuel burner
US3238992A (en) Solid-state control system
US4106889A (en) Burner ignition system
US3871814A (en) Electric ignition system
US3663150A (en) Safety ignition control system
US3488133A (en) Protected hot wire ignition system
US3384439A (en) Pulsed spark gas ignition and flame monitoring system
CA1083248A (fr) Systeme de commande de bruleur a interrupteur primaire de securite
US4089632A (en) Fuel control safety apparatus
US3399948A (en) Solid state ignition circuit for fuel bruners
US3276507A (en) Burner control system
US2449538A (en) Control apparatus
US3495925A (en) Combination igniter and temperature sensor
US3512909A (en) Electric ignition system
CA1123934A (fr) Circuit de controle pour un demarrage sur
US4167389A (en) Oil burner primary control for interrupted ignition system
US3609072A (en) Electric igniter system
US3059693A (en) Control system
US4406612A (en) Oil burner primary control for interrupted ignition system
US4099906A (en) Hot surface fuel ignition system