CA2394965C - Electronic detecting of flame loss by sensing power output from thermopile - Google Patents
Electronic detecting of flame loss by sensing power output from thermopile Download PDFInfo
- Publication number
- CA2394965C CA2394965C CA002394965A CA2394965A CA2394965C CA 2394965 C CA2394965 C CA 2394965C CA 002394965 A CA002394965 A CA 002394965A CA 2394965 A CA2394965 A CA 2394965A CA 2394965 C CA2394965 C CA 2394965C
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- Prior art keywords
- flame
- history
- electrical output
- microprocessor
- thermopile
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Classifications
-
- 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
- F23N5/10—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples
- F23N5/102—Systems for controlling combustion using devices responsive to thermal changes or to thermal expansion of a medium using thermocouples using electronic means
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2223/00—Signal processing; Details thereof
- F23N2223/06—Sampling
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F23—COMBUSTION APPARATUS; COMBUSTION PROCESSES
- F23N—REGULATING OR CONTROLLING COMBUSTION
- F23N2223/00—Signal processing; Details thereof
- F23N2223/08—Microprocessor; Microcomputer
Abstract
An apparatus for and method of rapidly detecting a flame out condition. A
thermopile receives heat energy from the flame and generates electrical power to enable operation of a microprocessor. This microprocessor periodically measures the output voltage of the thermopile at one second intervals. An average is taken of eight consecutive samples. A running history of eight averages is stored within a FIFO which serves as a history queue. This FIFO thus stores a digitized signature of the flame condition over the previous 64 seconds. Analysis by the microprocessor is able to make an early detection of the flame out condition by utilizing the current voltage measurements and the FIFO contents.
thermopile receives heat energy from the flame and generates electrical power to enable operation of a microprocessor. This microprocessor periodically measures the output voltage of the thermopile at one second intervals. An average is taken of eight consecutive samples. A running history of eight averages is stored within a FIFO which serves as a history queue. This FIFO thus stores a digitized signature of the flame condition over the previous 64 seconds. Analysis by the microprocessor is able to make an early detection of the flame out condition by utilizing the current voltage measurements and the FIFO contents.
Description
LLECTRONIC DETEanna nFinAME TAS3 BY STNsINGPOWER OUTPiIT
]MOM TgE OPILE
BACKGROUND OF THE INVENTION
1. &id ot'the Inveotion: The present invvention generally relates to systems for control of an appliance incolporating a flame and more particulariy relates to flame management systems.
S 2Dacription of the Drior 2 It is known in the art to employ vatious appGances for housshold and kWomW appdcatiom which utilin a fuel such as natural gas (i.e., methane), propane, or sims'!ar gaseous hydrocarbons. Typica>ly, such appliances have the primary heaa suppCcd by a main bunwr with a substarrcial presstuized gas input regulated via a main valve.
Ordiearity, the main burner consumes so much fuel and genarates so much heat that the main burner is ignited only as neassary. At otber times (e.g., the appliance is not used, etc.), the main valve is ciosed auinguisldng the mau- bunaer flame.
A aastomary approach to reigniting the main bumcr whenever needed is through the use of a piiot Iight. The pilot Gght is a second, much smaller burner, having a small prescurized gas input regulated via a pilot valve. In most installstions, the pilot light is intended to burn 1 S perpetually. Tlws, tunrning the maia vaive on provides fuet to the main burner whicb is quickly igated by the pdw light 9ame. Twning the main valve A eactingeushes the main burner, which can readily be reignited by the presence of the pilot light.
These fue(s, being toxic and highly flammable, are particularly dangerous in a gaseous state if released into the atnbient. Therefore, it is customary to provide certain safeiy features for msuriug that the pilot vaive and main valvc are never open when a flame is not present ptevertting rdease ofthe fitei arto the atmosplure. A standard approach uses a thermogenerative electricat device (e.g., thwmocouple, ttiecmopile, solar ceil, etc.) in ciose proximity to the properly opeauing flaune. Whenva the cotresponding flame is ptm+at, the thermocouple generates a aurent. A solenoid operated portion of the pilot valve and the main valve require the presence of a cnrent from the thermocouple to maintain the corresponding vaive in the open position.
Tlierefore, if no flame is present and the thermocouple(s) is cold and not generating curreat, neither the pilot vaJvv nor the main valve wi8 release any R-el. U.S. Patent No. 4,988,884, issued to Dunbar et al. shows a thermogenentive device thermally coupled to a Satne.
In practice, the pflot light is igdted infrequeatly such as at instsllation, loss of fuet supply, etc. Ignition is accomplished by mamwlly overriding the safety feature and holding the pilot valve open while the pilot ligla is lit using a match or piezo igniter. The manual ove:zide is hetd until the heat from the pilot Sattte is sufficient to cause the thernsocouple to generate enough cu:rEnt to a~ecgize the safety solenoid. T'he plot vah-e remains open as long as the thermocouple continues to generate sut5cient wrrent to actwte the pilot valve solenoid.
The safety thermoconple(s) can be replacad with a thetmopile(s) or other device for gwoeration of addiiionat electrical power. This additionat power may be desired for operating various indicators or for poweriag interfaces to equipment acternal to the appliaanoe. U.S. Patent No. 5,931,655, issued to Maher, Jr. and U.S. Patent No. 4,778,378, issued to Dolaick et al. show generation and usa e of such thernmally gmerated power. However, upon loss of Satrsc (e.g., from loss of fuel pressure), the thamocatpk(s) ceases generating edeaaicat current and the pilot valve and main valve are olosed. The delay from loss of tlame until closure of the valves depends upon a number of vatiahks. Of grqtest concene is the delay caused by heat energy retained in the appliance, including the the:mopile(s). That means that as the size and currrent generation ea~aty of the thetmopik(s) are it(cceased, the system delays are correspondingly increased.
]MOM TgE OPILE
BACKGROUND OF THE INVENTION
1. &id ot'the Inveotion: The present invvention generally relates to systems for control of an appliance incolporating a flame and more particulariy relates to flame management systems.
S 2Dacription of the Drior 2 It is known in the art to employ vatious appGances for housshold and kWomW appdcatiom which utilin a fuel such as natural gas (i.e., methane), propane, or sims'!ar gaseous hydrocarbons. Typica>ly, such appliances have the primary heaa suppCcd by a main bunwr with a substarrcial presstuized gas input regulated via a main valve.
Ordiearity, the main burner consumes so much fuel and genarates so much heat that the main burner is ignited only as neassary. At otber times (e.g., the appliance is not used, etc.), the main valve is ciosed auinguisldng the mau- bunaer flame.
A aastomary approach to reigniting the main bumcr whenever needed is through the use of a piiot Iight. The pilot Gght is a second, much smaller burner, having a small prescurized gas input regulated via a pilot valve. In most installstions, the pilot light is intended to burn 1 S perpetually. Tlws, tunrning the maia vaive on provides fuet to the main burner whicb is quickly igated by the pdw light 9ame. Twning the main valve A eactingeushes the main burner, which can readily be reignited by the presence of the pilot light.
These fue(s, being toxic and highly flammable, are particularly dangerous in a gaseous state if released into the atnbient. Therefore, it is customary to provide certain safeiy features for msuriug that the pilot vaive and main valvc are never open when a flame is not present ptevertting rdease ofthe fitei arto the atmosplure. A standard approach uses a thermogenerative electricat device (e.g., thwmocouple, ttiecmopile, solar ceil, etc.) in ciose proximity to the properly opeauing flaune. Whenva the cotresponding flame is ptm+at, the thermocouple generates a aurent. A solenoid operated portion of the pilot valve and the main valve require the presence of a cnrent from the thermocouple to maintain the corresponding vaive in the open position.
Tlierefore, if no flame is present and the thermocouple(s) is cold and not generating curreat, neither the pilot vaJvv nor the main valve wi8 release any R-el. U.S. Patent No. 4,988,884, issued to Dunbar et al. shows a thermogenentive device thermally coupled to a Satne.
In practice, the pflot light is igdted infrequeatly such as at instsllation, loss of fuet supply, etc. Ignition is accomplished by mamwlly overriding the safety feature and holding the pilot valve open while the pilot ligla is lit using a match or piezo igniter. The manual ove:zide is hetd until the heat from the pilot Sattte is sufficient to cause the thernsocouple to generate enough cu:rEnt to a~ecgize the safety solenoid. T'he plot vah-e remains open as long as the thermocouple continues to generate sut5cient wrrent to actwte the pilot valve solenoid.
The safety thermoconple(s) can be replacad with a thetmopile(s) or other device for gwoeration of addiiionat electrical power. This additionat power may be desired for operating various indicators or for poweriag interfaces to equipment acternal to the appliaanoe. U.S. Patent No. 5,931,655, issued to Maher, Jr. and U.S. Patent No. 4,778,378, issued to Dolaick et al. show generation and usa e of such thernmally gmerated power. However, upon loss of Satrsc (e.g., from loss of fuel pressure), the thamocatpk(s) ceases generating edeaaicat current and the pilot valve and main valve are olosed. The delay from loss of tlame until closure of the valves depends upon a number of vatiahks. Of grqtest concene is the delay caused by heat energy retained in the appliance, including the the:mopile(s). That means that as the size and currrent generation ea~aty of the thetmopik(s) are it(cceased, the system delays are correspondingly increased.
2 SUMMARY OF THE INYEN?TON
'rhe present invention overcomes the disadvantages of the prior art by providing a method of and appacatus for providing an earlier indication of a flame out condition.
In accordance with the prefenred mode of the present invention, a thermopile is utiliied to provide sufficient current to power asnall ntiaroprocessor and a number of other elearical components.
One ofthe fiuictieons of the oprocessor is to enea.sure he output vohage of the thennopile and maintain a history of that voltage output. By cotnpating the instamaneous output vohage to the history, the nnuaoproc~sor can diagnose a 8ame out condition firom the voltage output signature mich eartier than electcical cunreat generation by the thetmopile actually ceases.
The prefwed embodiment employs a two stage low voltage DC-to-DC converter which converts the thermopile output to power the nticroprocessor and other elecxrical components.
Upon being powered up, the microprocossor sampl.es the thecmopne output voltage once every sewnd. Every eight seconds an average is calculated. A complete "history" includes eight averages of eight readings each, coveting the last 64 seconds. These readings are atranged in time througb storage in a FffO push down stack. ?hat means that as eich new average is calculated, it is entered into the location in the stack for the latest reading. All ptevious readings are shifted baeic one place in the stack. The 9" last reading is shifted out of the stack and thus ddeted.
The contents of the stack provide a signature of the output voltage versus time curve of the thennopile output. Using the algorlthms descn'bed below in deWl, the flame out condition car be detected mueh eadier thau complete loss ofthermopile output.
'rhe present invention overcomes the disadvantages of the prior art by providing a method of and appacatus for providing an earlier indication of a flame out condition.
In accordance with the prefenred mode of the present invention, a thermopile is utiliied to provide sufficient current to power asnall ntiaroprocessor and a number of other elearical components.
One ofthe fiuictieons of the oprocessor is to enea.sure he output vohage of the thennopile and maintain a history of that voltage output. By cotnpating the instamaneous output vohage to the history, the nnuaoproc~sor can diagnose a 8ame out condition firom the voltage output signature mich eartier than electcical cunreat generation by the thetmopile actually ceases.
The prefwed embodiment employs a two stage low voltage DC-to-DC converter which converts the thermopile output to power the nticroprocessor and other elecxrical components.
Upon being powered up, the microprocossor sampl.es the thecmopne output voltage once every sewnd. Every eight seconds an average is calculated. A complete "history" includes eight averages of eight readings each, coveting the last 64 seconds. These readings are atranged in time througb storage in a FffO push down stack. ?hat means that as eich new average is calculated, it is entered into the location in the stack for the latest reading. All ptevious readings are shifted baeic one place in the stack. The 9" last reading is shifted out of the stack and thus ddeted.
The contents of the stack provide a signature of the output voltage versus time curve of the thennopile output. Using the algorlthms descn'bed below in deWl, the flame out condition car be detected mueh eadier thau complete loss ofthermopile output.
3 The thermopile has a certain internal resistance. In the preferred mode ofpracticing the invention, the main valve shares power from the same thecmopile. When the main valve is turned on, the total thermopfle output current inaeases resulting in a lowered theainopile output voltage.
The microproce~ssor is notified of the mode change so that the algorithm can u.commodate the mode change without faisdy detecing a flame out condition.
The microproce~ssor is notified of the mode change so that the algorithm can u.commodate the mode change without faisdy detecing a flame out condition.
4 :...... ........,: :_:..,.... .... ~ ... .._. ,..... :.....,: .. :.,, ......
...... .. . ... . . . . ..,.
BRIEF DESCWPTTON OF TSE DRAWINGS
Other objects of the present invention and many of the attendant advantages of the present invention wip be readily appreciated as the same becomes better understood by reference to the S following detmled description when considered in conaadion with the accompanying drawings, in which like refercnce numerals designate like parts throughout the figures thereof and wherein:
FIG.1 is a graph showing the theemopile output voltage as a fiuiction of time;
Fig: 2 is a simplifted schmatic electrical diagtam of the present invention;
Tig. 3 is a graph, simiiar to Fig. 1, showing eortain key poiuts;
Fig. 4 is a schematic diagram showing operation of the memory which maintains the output voltage hiscory, FTg. 5 is a basic dagam of the key iaputs and outputs of the microprocessor, and F'ig. 6 is a detailed flow chart of the fvm ware of the prefetred mode of the present invention.
...... .. . ... . . . . ..,.
BRIEF DESCWPTTON OF TSE DRAWINGS
Other objects of the present invention and many of the attendant advantages of the present invention wip be readily appreciated as the same becomes better understood by reference to the S following detmled description when considered in conaadion with the accompanying drawings, in which like refercnce numerals designate like parts throughout the figures thereof and wherein:
FIG.1 is a graph showing the theemopile output voltage as a fiuiction of time;
Fig: 2 is a simplifted schmatic electrical diagtam of the present invention;
Tig. 3 is a graph, simiiar to Fig. 1, showing eortain key poiuts;
Fig. 4 is a schematic diagram showing operation of the memory which maintains the output voltage hiscory, FTg. 5 is a basic dagam of the key iaputs and outputs of the microprocessor, and F'ig. 6 is a detailed flow chart of the fvm ware of the prefetred mode of the present invention.
5 DETA,ILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. i is a diagram 10 showing the output voltage versus time of the thermop's1e of the preferred mode of the present inveation under various conditions. Shon}y after. flune on, point 12 is reac,hed whereat the tharmopile (not shown) begins generating a measurable voltage. The thamopile output is, of coum a function of the temmperatsue within the combustion chamber (actually, as readfly la,owA to those of sldll in the art, the output is a fitncEion of the temperacure differential betweea the poles, only one of which is thecmaUy coupled to the combustion chamber). The temperature of the combustiort chamber (and hence the thermopile output) cont'uuwes to rise over time until it reaches a rdativdy stable level having slight amplitude watiatiou such as the rellative nunimum at point 14.
The system of the preferred mode has more than one flame level of the main burner. Point 16 represents the rdatively stable levd of a second mode (with lower flame energy input and . )5 output). A mode change is accomplished eithet autotnatically by a thermostat calling for heat, or manually by acrion of the user (e.g., a button on a remote control device).
This mode change is comemuricated to the microproceasw as discussed in greater detail below to enable the mieroproeessor to Ofereruiate mode change from Aame out conditions.
Flame out oams at poau 18. Point 20 corresponds to a reduction in combustion chamber temperature at which the thamopNe ceaims to produce a measurabk output. As can be seen by the cauve of diagratn 10 from point 18 to point 20, a charactetistic signamre is present. In acaordanee with the pnesent inveoon, the microprocessor coniinuousiy and periodically measures
Fig. i is a diagram 10 showing the output voltage versus time of the thermop's1e of the preferred mode of the present inveation under various conditions. Shon}y after. flune on, point 12 is reac,hed whereat the tharmopile (not shown) begins generating a measurable voltage. The thamopile output is, of coum a function of the temmperatsue within the combustion chamber (actually, as readfly la,owA to those of sldll in the art, the output is a fitncEion of the temperacure differential betweea the poles, only one of which is thecmaUy coupled to the combustion chamber). The temperature of the combustiort chamber (and hence the thermopile output) cont'uuwes to rise over time until it reaches a rdativdy stable level having slight amplitude watiatiou such as the rellative nunimum at point 14.
The system of the preferred mode has more than one flame level of the main burner. Point 16 represents the rdatively stable levd of a second mode (with lower flame energy input and . )5 output). A mode change is accomplished eithet autotnatically by a thermostat calling for heat, or manually by acrion of the user (e.g., a button on a remote control device).
This mode change is comemuricated to the microproceasw as discussed in greater detail below to enable the mieroproeessor to Ofereruiate mode change from Aame out conditions.
Flame out oams at poau 18. Point 20 corresponds to a reduction in combustion chamber temperature at which the thamopNe ceaims to produce a measurabk output. As can be seen by the cauve of diagratn 10 from point 18 to point 20, a charactetistic signamre is present. In acaordanee with the pnesent inveoon, the microprocessor coniinuousiy and periodically measures
6 the thecmopile output such that this flame out signature can be detected well before point 20.
Detecting flame out before loss ofthennopile output provides available electrical energy for orderly shut down functidiiis.
Fig. 2 is a vey basic electrical diagnm 22 of the power circuitry of the present invention.
Thermopile 24 is structuredin accordance with the prior art. Resistor 26 represeats the internal resistance of thaaropile 24.
PBot valve 28 has a solenoid (not separately shown) which holds the pilot valve closed whenever sufficient cLww flows through the circuit. Similady, the internal solenoid (also not separately shown) of main valve 32 holds the main valve closed whenever sufficient current flows ttmugh the assocaated circuit.
DC-to-DC conversion faaft 36 convots the rdatively low voltsge output of thermopile 24 to a sufficiently large voltage to power the electrornc control ccarc,uitry, includ'mg the ndcroprocessor. In accordance with the prefetred mode of the present invention. DC-to-DC
conversion facility 36 consists of two DC-to-DC converters. The first converter operates at the extremelyr low tbermopite output voltages expenenced duzing combustion chantber warm up to genetate a higha voltage to start the high-effiaenc.y. secord DC-to-DC
comerter (see also Fig.
1). The other DC-to-DC convener, once started, can keep converting at much lower input voltage and generate much more power from the limited themopile output for the system during normal operation.
F'~g,. 3 is diagram 10 (see also Fig. 1) showing cectain additional points of interest c.oecerning the presait invention. In accordance witb the preferred mode, point 38 represents the point at which IJC-to-DC conversion facility 36 (see also Fig. 2) begins produang usefol electrical power. The above identified co-pending patent application descn'bes the DC-to-DC
converter in additional detail.
Detecting flame out before loss ofthennopile output provides available electrical energy for orderly shut down functidiiis.
Fig. 2 is a vey basic electrical diagnm 22 of the power circuitry of the present invention.
Thermopile 24 is structuredin accordance with the prior art. Resistor 26 represeats the internal resistance of thaaropile 24.
PBot valve 28 has a solenoid (not separately shown) which holds the pilot valve closed whenever sufficient cLww flows through the circuit. Similady, the internal solenoid (also not separately shown) of main valve 32 holds the main valve closed whenever sufficient current flows ttmugh the assocaated circuit.
DC-to-DC conversion faaft 36 convots the rdatively low voltsge output of thermopile 24 to a sufficiently large voltage to power the electrornc control ccarc,uitry, includ'mg the ndcroprocessor. In accordance with the prefetred mode of the present invention. DC-to-DC
conversion facility 36 consists of two DC-to-DC converters. The first converter operates at the extremelyr low tbermopite output voltages expenenced duzing combustion chantber warm up to genetate a higha voltage to start the high-effiaenc.y. secord DC-to-DC
comerter (see also Fig.
1). The other DC-to-DC convener, once started, can keep converting at much lower input voltage and generate much more power from the limited themopile output for the system during normal operation.
F'~g,. 3 is diagram 10 (see also Fig. 1) showing cectain additional points of interest c.oecerning the presait invention. In accordance witb the preferred mode, point 38 represents the point at which IJC-to-DC conversion facility 36 (see also Fig. 2) begins produang usefol electrical power. The above identified co-pending patent application descn'bes the DC-to-DC
converter in additional detail.
7 The output of the DC-to-DC converta begins to power the microprocessor such that it is fully operational at point 40. The time between points 40 and 42 is utilized by the microprocessor to inicialize for fall operation. This initialization includes setting various status registers and establishing certain initial conditions. Upon attaining fnll operation at point 42, the microprocessor begins to sample the therrnopile output voltage as described below.
The thermopile output voltage value is converted to a ten bit digital quantity and satnpled by the microprocessor once per second. The points in range 44 show how these samples can be used to desenbe the signature of the thermopile output voltage versus time profile.
Fig. 4 is a functional diagram of the memory which stores the samples of thermopile output voltage received by the microprocessor. This memory is arranged as an eight cell current queue and an eiglrt cell history queue as shown. Each ten bit sample is presented along path 52.
These samples are taken once per second and stored in succeeding cells represented by arrow 50.
The current queue stores eaight ten bit values. When all eight have been received representing the samples taken over an eight second petiod of time, the mathetnatical average of these eight samples is computed and transferred via path 54 to the history queue.
The history queue includes eight ten bit celis which are arranged as a FIFO
with the older averages being shifted in the direction of arrow 56. Thus, the history queue can store eight different averages representing a period of 64 seconds. As is explained in more detait below, it is the history queue which stores the digitized signature of the flame condition over that 64 seconds.
Portion 58 of the history queue contains the "old" average as described below.
The thermopile output voltage value is converted to a ten bit digital quantity and satnpled by the microprocessor once per second. The points in range 44 show how these samples can be used to desenbe the signature of the thermopile output voltage versus time profile.
Fig. 4 is a functional diagram of the memory which stores the samples of thermopile output voltage received by the microprocessor. This memory is arranged as an eight cell current queue and an eiglrt cell history queue as shown. Each ten bit sample is presented along path 52.
These samples are taken once per second and stored in succeeding cells represented by arrow 50.
The current queue stores eaight ten bit values. When all eight have been received representing the samples taken over an eight second petiod of time, the mathetnatical average of these eight samples is computed and transferred via path 54 to the history queue.
The history queue includes eight ten bit celis which are arranged as a FIFO
with the older averages being shifted in the direction of arrow 56. Thus, the history queue can store eight different averages representing a period of 64 seconds. As is explained in more detait below, it is the history queue which stores the digitized signature of the flame condition over that 64 seconds.
Portion 58 of the history queue contains the "old" average as described below.
8 Fig. 5 is a simplified diagram of microprocessor 60. In the preferred mode, rnicroprocessor 60 is an 8-bit AVR model AT90LS8535 microprocessor available from ATMEI.*
It is a high perfOrmance low power, restricted insuuction set Ci.c., RISC) microprocessor. In the prefeczed raode, microprocessor is clocked at one megabertz to save power, even though the selected device may be clocked at up to four megahertz.
The two primary inputs to microprocessor 60 are the thermopile output voltage received via iaput 62 and the manual mode change information received via input 64. The thermopile output voltage is input otxx per second. The mode change infornation. on the other hand, is received aperiodically in response to manual action by the user.
F'~ 6 is a flowchart 72 of the fiim ware of the preseut inveetion which operates in microprocessor 60. At first start up Vtp% is initialized to 100%, and entry counter is set to zero.
A"wake up" clOck intetYUpts microprocessor 60 at one second intervals causing the program to :tart at element 74. Element 76 first deterntines whether there is a status change concerning the main fud valve. As explained in teferencs to Fig. 1 point 16, such a status change imrolves a different thermopile load and therefore a different thermopile apparart output voltage. The progmm toust be notified via path 64 (see also F'ig. 5) of such status charVes to prCVent a false indication of flame out. It should be noted that the one second wake up inmval is quick enough to accoaanodate the status c6ange. If a main valve status change has oeuured, element 78 resets the erury counter. Element 80 fiUs the current queue with aA zeroes to start the analysis over again at the nr-v input vohage. After that, control is given to eknment 90 for exit.
If elemeet 76. has not detected a main valve status change, control is given to element 84 to secure the wrraM therinopile output voltage value in the eight entry a,rrent quene. Element 88 detemines ifthe history queue has a complete history (i.e., eight averages which represent 64 seconds of Vtp vahms). If tbe history queue does not ye.t have eig6t entries, ekment 92 increments the counter. Control is given to element 94 which deterntines whether the current queue is full (i.e., eigbt entries). If no, coetrol is given to elemart 96 for exit.
It is a high perfOrmance low power, restricted insuuction set Ci.c., RISC) microprocessor. In the prefeczed raode, microprocessor is clocked at one megabertz to save power, even though the selected device may be clocked at up to four megahertz.
The two primary inputs to microprocessor 60 are the thermopile output voltage received via iaput 62 and the manual mode change information received via input 64. The thermopile output voltage is input otxx per second. The mode change infornation. on the other hand, is received aperiodically in response to manual action by the user.
F'~ 6 is a flowchart 72 of the fiim ware of the preseut inveetion which operates in microprocessor 60. At first start up Vtp% is initialized to 100%, and entry counter is set to zero.
A"wake up" clOck intetYUpts microprocessor 60 at one second intervals causing the program to :tart at element 74. Element 76 first deterntines whether there is a status change concerning the main fud valve. As explained in teferencs to Fig. 1 point 16, such a status change imrolves a different thermopile load and therefore a different thermopile apparart output voltage. The progmm toust be notified via path 64 (see also F'ig. 5) of such status charVes to prCVent a false indication of flame out. It should be noted that the one second wake up inmval is quick enough to accoaanodate the status c6ange. If a main valve status change has oeuured, element 78 resets the erury counter. Element 80 fiUs the current queue with aA zeroes to start the analysis over again at the nr-v input vohage. After that, control is given to eknment 90 for exit.
If elemeet 76. has not detected a main valve status change, control is given to element 84 to secure the wrraM therinopile output voltage value in the eight entry a,rrent quene. Element 88 detemines ifthe history queue has a complete history (i.e., eight averages which represent 64 seconds of Vtp vahms). If tbe history queue does not ye.t have eig6t entries, ekment 92 increments the counter. Control is given to element 94 which deterntines whether the current queue is full (i.e., eigbt entries). If no, coetrol is given to elemart 96 for exit.
9 If the history queue has a complete history (i.e., eight avenges representing non-zero entries over a 64 second period) or the cwrent queue is full (i.e.. eigld non=zero entries), control is given to dement 98 for calculation of the aurrent rutming average. The use of this nuuiing average smooths the responses to compensate for the small variations always present (see point 14 of Fig. 1). Element 100 detetmines whether the current queue rolls over. If yes, control is given to elemeat 102 to deterntine whether it is the first time the wtreat queue rolls over. If yes, element 112 sets all of history queue entries to the running average tanes a percacuage (Vtrp%) and coatrol is reauaed to ekomm 110 for Ardw processing. If element 102 determietes it is not the 8 entry after start up or a mode change, control is given to element 104 which determines whether the history queue is full. If no, control is given to elennatt 106 to detesmine if the new nuuing average is less than the old average. If not, element 108 takes one half of the sum of the mnrnng average and the old average and lOls the history queue with the result.
If dement 104 finds that the history queue is fuq or finds the cunm running average to be lcss than the old average, element 114 calculates the old average and elanent 116 updates the historical queue.
CoQtrol is then given to eletneent 110 for furtber processing.
Element 1] 0 calculatas the voltage percentage which equals the old average divided by the ruming average, and the resub is clamped to 1001@ -= 143%. Control is then given to element IS
118 to detecmine if the. percxntage is equal to 143. If no, a shut down condition is not detected and the procedure exits at eleenent 122. If yes, a shut down corAtion is detected and element 120 perfom the shut down funcxions before exiting at element 122.
Iiaving thus described the preferred embodiments of the present invention, those of skill in the art will be readily able to adapt the teachings found herein to yet other embodiments within the scope of the claims hereto attached.
If dement 104 finds that the history queue is fuq or finds the cunm running average to be lcss than the old average, element 114 calculates the old average and elanent 116 updates the historical queue.
CoQtrol is then given to eletneent 110 for furtber processing.
Element 1] 0 calculatas the voltage percentage which equals the old average divided by the ruming average, and the resub is clamped to 1001@ -= 143%. Control is then given to element IS
118 to detecmine if the. percxntage is equal to 143. If no, a shut down condition is not detected and the procedure exits at eleenent 122. If yes, a shut down corAtion is detected and element 120 perfom the shut down funcxions before exiting at element 122.
Iiaving thus described the preferred embodiments of the present invention, those of skill in the art will be readily able to adapt the teachings found herein to yet other embodiments within the scope of the claims hereto attached.
Claims (8)
1. An apparatus comprising:
a. a flame;
b. a device thermally coupled to said flame which generates an electrical output in response to heat received from said flame;
c. an electrical circuit responsively coupled to said electrical output which provides early detection of a flame out condition by sampling said electrical output;
d. wherein said electrical circuit further comprises a microprocessor; and e. wherein said microprocessor is powered by said electrical output.
a. a flame;
b. a device thermally coupled to said flame which generates an electrical output in response to heat received from said flame;
c. an electrical circuit responsively coupled to said electrical output which provides early detection of a flame out condition by sampling said electrical output;
d. wherein said electrical circuit further comprises a microprocessor; and e. wherein said microprocessor is powered by said electrical output.
2. An apparatus according to claim 1 wherein said microprocessor utilizes said sampling of said electrical output to produce a history of said electrical output which provides early detection of said flame out condition by comparing said sampling of said electrical output with said history of said electrical output.
3. An apparatus according to claim 2 wherein said history is stored within a history queue.
4. A method of early prediction of a flame out condition in a system employing a flame comprising: a. generating an electrical output in response to heat received from said flame; b. sampling said electrical output to determine an amplitude; c.
continuing to sample said electrical output to produce an amplitude history; d. comparing a current sample to said history; and e. assuming a flame out condition when said comparing step suggests a flame out.
continuing to sample said electrical output to produce an amplitude history; d. comparing a current sample to said history; and e. assuming a flame out condition when said comparing step suggests a flame out.
5. A method according to claim 4 wherein said amplitude history contains samples which are a plurality of seconds apart.
6. A method according to claim 5 wherein said amplitude history contains a plurality of samples taken once every second.
7. A method according to claim 6 wherein said plurality of samples taken within a single second further comprises eight.
8. A method according to claim 7 wherein said plurality of seconds further comprises eight seconds.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US09/448,000 US6478573B1 (en) | 1999-11-23 | 1999-11-23 | Electronic detecting of flame loss by sensing power output from thermopile |
| US09/448,000 | 1999-11-23 | ||
| PCT/US2000/032003 WO2001038793A1 (en) | 1999-11-23 | 2000-11-22 | Electronic detecting of flame loss by sensing power output from thermopile |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2394965A1 CA2394965A1 (en) | 2001-05-31 |
| CA2394965C true CA2394965C (en) | 2009-08-25 |
Family
ID=23778619
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002394965A Expired - Lifetime CA2394965C (en) | 1999-11-23 | 2000-11-22 | Electronic detecting of flame loss by sensing power output from thermopile |
Country Status (3)
| Country | Link |
|---|---|
| US (1) | US6478573B1 (en) |
| CA (1) | CA2394965C (en) |
| WO (1) | WO2001038793A1 (en) |
Families Citing this family (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US8333584B2 (en) * | 2005-10-28 | 2012-12-18 | Beckett Gas, Inc. | Burner control |
| US7726876B2 (en) | 2007-03-14 | 2010-06-01 | Entegris, Inc. | System and method for non-intrusive thermal monitor |
| CN101809376B (en) * | 2007-08-28 | 2013-05-22 | Aos控股公司 | Storage-type water heater having tank condition monitoring features |
| US20110277706A1 (en) * | 2010-05-13 | 2011-11-17 | Arnold J Eric | Gas-fired heating device having a thermopile |
| US8457835B2 (en) * | 2011-04-08 | 2013-06-04 | General Electric Company | System and method for use in evaluating an operation of a combustion machine |
| US9752990B2 (en) | 2013-09-30 | 2017-09-05 | Honeywell International Inc. | Low-powered system for driving a fuel control mechanism |
| US10208954B2 (en) | 2013-01-11 | 2019-02-19 | Ademco Inc. | Method and system for controlling an ignition sequence for an intermittent flame-powered pilot combustion system |
| US9494320B2 (en) | 2013-01-11 | 2016-11-15 | Honeywell International Inc. | Method and system for starting an intermittent flame-powered pilot combustion system |
| US11236930B2 (en) | 2018-05-01 | 2022-02-01 | Ademco Inc. | Method and system for controlling an intermittent pilot water heater system |
| US11656000B2 (en) | 2019-08-14 | 2023-05-23 | Ademco Inc. | Burner control system |
| US11739982B2 (en) | 2019-08-14 | 2023-08-29 | Ademco Inc. | Control system for an intermittent pilot water heater |
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| US3301307A (en) * | 1963-11-12 | 1967-01-31 | Ngk Insulators Ltd | Device for detecting the configuration of a burning flame |
| US3877002A (en) * | 1973-05-25 | 1975-04-08 | Omni Spectra Inc | Intrusion detecting system |
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| US4639717A (en) * | 1985-07-15 | 1987-01-27 | Electronics Corporation Of America | Method and apparatus for monitoring flame condition |
| US4696639A (en) * | 1986-11-06 | 1987-09-29 | Honeywell Inc. | Self-energizing burner control system for a fuel burner |
| US4778378A (en) | 1986-12-03 | 1988-10-18 | Quantum Group, Inc. | Self-powered intermittent ignition and control system for gas combustion appliances |
| JPS63161314A (en) * | 1986-12-23 | 1988-07-05 | Haaman:Kk | Incomplete combustion detecting apparatus for burner |
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-
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- 2000-11-22 CA CA002394965A patent/CA2394965C/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| WO2001038793A1 (en) | 2001-05-31 |
| CA2394965A1 (en) | 2001-05-31 |
| US6478573B1 (en) | 2002-11-12 |
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