US2582334A - Thermostatic fuel control system - Google Patents

Description

Jan. 15, 1952 F. H. HUNTLEY 2,582,334

THERMOSTATIC FUEL CONTROL SYSTEM Filed Aug. 25, 1949 2 SHEETS-SHEET l Jan. 15, 1952 HUNTLEY 2,582,334

THERMOSTATIC FUEL CONTROL SYSTEM Filed Aug. 25, 1949 2 SHEETS-SHEET 2 I I E1. 5

I B f x2514 .arrak/m'rs Patented Jan. 15, 1952 THERMOS TATIC FUEL CONTROL SYSTEM Frederick H. Huntley, Lansing, Mich, assignor to Motor Wheel Corporation, Lansing, MiclL, a corporation of Michigan Application August 25, 1949, Serial No. 112,369

11 Claims.

This invention relates to an oil control device and more particularly to a control device for regulating the supply of liquid fuel to gravity fed oil burners such, for example, as a vaporizing type fuel oil burner.

In a vaporizing type fuel oil burner the oil is vaporized by the heat of the fiame preparatory to mixing with air and burning. If the burner is burning, say, for example, with only a low pilot flame and the fuel oil is then fed into the burner at too fast a rate, the heat generated by the low pilot flame will be insufficient to thoroughly vaporize all of the oil flowing into the burner and consequently the oil will tend to pool for a short period, the burner will run inefiiciently and the attainment of a high fire will be delayed. In other words, the flame or heat generated by the burner gets out of step temporarily with the increased rate of feed which results in inefficient operation of the burner.

It is an object of this invention to produce an oil control which will keep the rate of oil feed in step with the burner flame, that is, with the ability of the burner to properly vaporize the fuel preparatory to burning the same. Thus, thisinvention contemplates an oil control which will produce more efiicient combustion in a vaporizing type burner and particularly in those periods when the rate of oil feed into the burner is being accelerated or decelerated.

In the drawings:

Fig. 1 is an elevation partly in section show ing the oil control which is the subject of this invention. 1

Fig. 2 is a fragmentary section showing the position of the thermostatic control bars when the burner is burning at low clean fire.

Fig. 3 shows the position of these bars when the burner is burning at medium or intermediate fire.

Fig. 4 shows the position of these bars at high fire.

tween the two control bars.

Figs. 6 and 7 are slide and end elevations respectively showing a second modified form of connection between the control bars.

Figs. 8 and 9 are side and end elevations respectively showing a third form of connection between the control bars.

Referring more particularly to the drawings, there is shown a constant level oil control device comprising a main casing I having a liquid supply chamber therein to which liquid is supplied and maintained at a constant level by Fig. 5 shows a modified form of connection be- I mechanism not shown but well known in the art, see, for example, United States Letters Patent Nos. 2,068,138, 2,120,364, and 2,369,739.

Liquid-fuel is supplied to the main casing I through inlet 2 and flows out of casing I into the burner through outlet 3 which is controlled by valve 4. Valve 4 is controlled by pin 5. As pin 5 rises, valve 4 opens and admits more fuel from casing I to outlet 3, and as pin 5 islowered, valve 4 moves toward closed position and decreases the flow of fuel out of outlet 3.

The opening and closing of pin 5 is controlled by two motors generally designated 6. and I, Motors 6 and 1 each take the form of laminated thermostatic bimetal bars 8 and 9 respectively, anchored at one end upon support II] as at II and I2 respectively. Bar 8 is energized by electrical resistance heating coil I3 which is in heat exchange relation therewith and bimetal bar 9 is energized by electrical resistance heating coil I4 which is in heat exchange relation therewith.

Energy is supplied to heating elements I3 and I4 from a step down transformer I5. The secondary winding I6 of the step down transformer has one terminal connected by a conductor I1 and branch conductors I8 and I9 with one terminal of each of the heating elements I3 and I4 respectively. The other terminal of the secondary winding I6 is connected by a wire 20 to the,

movable contact leaf 2| of a room thermostat generally designated 22. The fixed contact 23 of the room thermostat is connected by a wire 24 to the other terminal of the heating element I4 of the heat motor I. The other terminal of heat ing element I3 of heat motor 6 can be connected to the other terminal of the secondary winding It by a wire 25. The fiow of current through wire 25 can be controlled by a conventional mechanism, such as a pilot selector switch or a thermostat positioned without the building being heated. By way of illustration, a pilot selector switch 26 is installed in line 25 and controls the flow of current therethrough.

The free end of bimetal bar 8 is provided with an extension 21 fixed thereto in any conventional manner but preferably by riveting. The free end of bimetal arm 9 is provided with two exten sions 28 and 29 fixed thereto in any suitable manner but preferably by riveting. Extensions 21, 28 and 29 preferably are in the form of sheet metal stampings. A pin 30 is fixed at its upper end ,to extension 21 as at 3|. One wall of the housing 32 in which the heat motors 6 and I are mounted carries a fixed stop 33 upon which extension 21 rests when motor 6 is denergizecl The pin 3| projects through the bifurcated or forked end 34 of extension 28. A disc 35 is fixed to the lower end of pin 39. Disc 35 overlaps the arms of fork 34. An adjustable stop screw 31 is mounted in the top of casing 32 and arrests the upward movement or deflection of extension 27 and heat motor 6. A An adjustable screw 38] is; mounted on arm 21 andextends downwardly'towa'rd arm 28 on heat motor 1 for purposes described below. I

The operation of my device is as follows: As shown in Fig. 1, thermostatic switch 2| and switch 25 are both open so that heat motors 6 and I are deenergized. At this tiine'extension 29, which contacts pin'5,"has*depressed pin so that valve 4 is in low pilot position, that is, admitting just enough fuelfro'mrfuel chamber 89, through slot 8| in the end ofthe valve 4 and through outlet 3 to maintain a lowpilot flame in the burner. Valve 4 is biased toward open-position by acoil spring (not shown) 'ina conventional manner. The low'er end of pin 38 is outof Contact with arm 28 and' arrn 21"rests upon stop 3'3 and out of contact'with'pin'3l.

Heat'motors 6 and 1 each fiex upwardly about their anchors II and I2, respectively, upon a rise in temperature, such as occurs when current "flows through heating elements l3 and I4.

If switch'29is closed, then current flows from secondarywindiiig l6'-of the transformer through heating element laand heat motor 6 is deflected upwardly to the-position shown in Fig. 2 wherein the'arm 2'! abuts the lower end of stop screw 31 to therebyhold arm 2'! against any further upward movement. As arm 2'! moves upwardly it acts through disc 35 to pick up the forked end 35 of extension 28 and thereby flex heat motor -'l and extension 29 upwardly thereby caus ing pin-5 and valve 4 to"rise to low clean fire positionwherein'fuel'flows throughoutlet 3 into the'burner atabout twenty-fivepercent of the rateat-which it flowsthrough outlet 3 at high fire. Thus, to recapitulate, if thermostat 2'2'is'0pen and'notcalling for heat, then with switch 29open, 'valve 4 is'in low'pilot position and with-switch '26 closed, valve '4 is in low clean 'fire p'ositionso that'the burner is'gen erating-about twenty fivepercent (25%) of itsmaximurn heat output.

Whenever-thermostat 2 2 calls f o'r-"h'eat. switch '2 l is closed so that curre'nt "flows from the 'secondary e'oil l-ES through'heaterpofl 14 thereby causing heat motor" to? warp or 'fiexupwardly relieving pin 5' and 2 thereby causing "valve 4 (which is biased towa'rd open position bya spring (not shown) to open from its lower position to high fire position, Fig. 4. The lower position of valve 4 may be-low-pilot,-Fig.-1,'orl0W clean fire, Fig. 2, depending upon the'p'osition of the bimetal bar "8. When theburner goes-from low cleanfire, Fig. '2, to high-firefno delay in feeding the oil is necessary because the burner is hot enough to vaporize 'all the oil admitted to the burner.

If the burner is on low pilot and then goes from low pilot, Fig. 1,to high fire, Fig. 4, too rapidly, therate of vaporization of the oil will not keep step with the rate of admission of the oil into the burner and the burner'will tend to pool for'ashort period. "The net result is the position shown in Fig. 3 untilbimetal bar '9"strikesthe"lower end'of screw 38. .mits valve 4 to open to about thirty percent This per- (30%) of full feed position rapidly. Since bar 8, which is not energized, has considerable resilience, an added load is put on bar 9 and the bar 9 in passing from about thirty percent (30%) of maximum feedto full feed position, Fig. 4,

"is slowed'down dueto the resilience or resistance to flexing of bar "8.

Fig. 4. shows the position of the control at high fire, that is, when valve 4 is'wide'open and the oil is being fed into the burner at its maxium rate.

Conversely, when switch'29 isopen and heating element'lil deenergized, the going from high fire (Fig. 4) to low pilot (Fig. 1) is accelerated when heating element M on bar 9 is deenergized. The added stiffness of bar 9, which 'r'etar'ds'bar 9 going up, accelerates it going down until the point is reached when the connectionbetween bar '8 and bar 9 is discontinued. This action'is very'desirable as its effect is to "prevent 'overrun'of room temperature which is a condition which is encountered in milder temperature days.

High fire position of the control, Fig. 4, is reached both when the'fire comes up from low K pilot position (Fig. 1) and from low clean fire position '(Fig. 2) but there is no limiting or retarding effect on theupward fiex-ingof bar 9 as the fire comesfrom low clean fire position shown in Fig. 2 to high fire shown in' Fig. 4 because switch 2 6 will be closed,heat motor l3 energized, bar 8 flexed upwardlyto its'top or high fireposition with screw 38 clear-of'bar 9 before heat motor 14 is energized'and bar 9 starts its upward travel from low clean fire tohigh fire position unrestrained by ba'rB. The stop '38 is adjustable so that the timing-of'the movement of bar 9 can be regulated. p

The modifiedform of control shown in Fig. 5 is identical with that shown in-Figs. 1'to'4 except that screw 3B'hasbeen'omitte'd and extension 40 (which corresponds to extension 28) on bar 9 has its outer 'en'dd'ividedinto" a forkhaving a'lower finger 4i and anupper finger 42 which straddle pin 39. Finger 4! contacts disc whenbar 8 is energized'and flexed upwardly thereby flexing bar 9 upwardly and permitting valve 4to rise to low clean fireiposition, as indicated-in Fig. 2. Finger"'42-takes the place of screw 33 and serves the samefunction. Hence, if bar 8 is not energized, then if bar 9 is energized, bar 9 will rise upwardly withoutrestr'aint fromlow pilot toabout thirty percent (30%) of full fire position whereupon finger"'42 contacts extension z'l and bar 8 now yieldably resists or 'r'es'tiains" further upward I flexing of 'bar B-andthus slows downthe rate of increase in the feedof-fuel into the burner in the same manner as previously desc'ribed with the principal form or this invention.

Figs. Gand 7 show'a second modified form of the connection between bars 8 and 9. The "end of extension*4-5 'on' arm -8 is bifurcated as at i 46 and turned downwardly and then inwardly as at 41. The end of extension 48 of'arm 9 is bifurcated as at 59 and then turned upwardly and inwardly'as at 5 l. A-1ostmotion "connection 52'in the form of a doubleflcross member is mounted upon the bifurcated ends 46 and 56. The ends 53-and 54 of the double cross connection 52 are positioned between the arms of the bifurcated ends 46 and 59 and project beyond extensions 45 and. 48 respectively and the cross bars 55 and 56 extend across the arms of the bifurcated ends.

Lost motion connection 52 cooperates-with the ends of arms 8 and 9 to perform the same function performed by stop screw 38 and pin in the principal form of this invention. As shown in Figs. 6 and 7, bars 8 and 9 are deenergized and valve"4 is in low pilot position. When bar 8 is energized by closing switch 26, then as bar 8 warpsupwardly bifurcated end 41 of extension 45 contacts crossbar and cross bar 56 contacts end 5| of extension 48 so that arm 8 acts through connector 52 to pick up arm 9 and permit valve 4 to open to low clean fire position, Fig. 2. The upward flexing of arm 8 is limited by stop 31. If bar 9 isenergized, then it warps or flexes upwardly causing inwardly turned end 5| to move upwardly away from cross bar 56 and cross bar 56 will now be picked up by extension 48 and bar 55 will move away from end 41 thus permitting valve 4 to openrapidly until cross bar 55 contacts the under face of arm 45 whereupon the inherent resilience of arm 8 now acts through bar 52 to retard the speed of arm 9 and thus slow down the rate of opening of valve 4 as it opens from about thirty percent (30%) of the full rate of fuel feed to the full or high fire rate of feed.

' In the modified form shown in Figs. 8 and 9, arms 8 and 9 are provided with extensions 60 and -6l.' Abonnectingbar 62 is pivoted as at 63 in the downwardly turned ears 64 at the end of extension60. Extension 6! is provided with a pair of upwardly turned ears 65 each provided with elongated openings 66 into which extend shoulders 61'on the lower end of bar 62. -As shown in Figs. 8 and 9, both bars 8 and 9 are deenergized. When bar 8 is energized by closing switch 26, bar 8 warps upwardly and acts through bar 62, shoulders 6'! and the upper ends of slots 66 to pick up Ibar 9 and raise it to the low clean fire position, as illustrated in Fig. 2. If bar 8 is deenergized by opening switch 26 and bar 9 is energized by closing of switch 2|, then bar 9 will rise rapidly until shoulder 6'! on bar vI52 contacts the bottom of slots 66. This occurs when bar 9 and valve 4 reach a position of about thirty percent (30%) of the maximum rate of fuel feed. At about thirty percent (30%) of the full fire position arm 9 contacts the lower end of bar 62 and at this time bar 8, as in the other forms of the invention, acts through connector bar 62 to retard the rate of opening speed of bar 9 from about thirty per- ;cent (30%) to high fire position. v

I'claim: 1. In a control device adapted for regulating the supply of liquid fuel to a liquid fuel burner comprising a casing having a chamber for liquid fuel and an outlet from said chamber, a metering valve for regulating the flow of fuel through said outlet, a motor operable when energized to shift said metering valve from pilot to high fire position, means for yieldably resisting the action of said first motor and retarding the rate of movement of the valve in an opening direction under the influence of said first motor, and a second motor operable when energized to render said means ineffective to resist the action of the first motor.

2. In a control device adapted for regulating the supply of liquid fuel to a liquid fuel burner comprising a (Easing having a chamber for liquid fuel and an outlet from said chamber, a metering valve for regulating the flow of fuel through said outlet, a motor operable when energized to shift said metering valve from pilot to high fire position, resilient means for yieldably resisting the action of said first motor and retarding the rate of movement of the valve in an opening direction under the influence of said first motor after the first motor has opened the valve substantially beyond pilot fire position, and a second motor operable when energized to render said resilient means ineffective to resist the action of the first motor and to shift said valve to low clean fire position.

3. In a control device adapted for regulating the supply of liquid fuel to a liquid fuel burner comprising a casing having a chamber for liquid fuel and an outlet from said chamber, a metering valve for regulating flow through said outlet, a heat motor operable when energized to shift said valve from pilot to high fire position, a, second heat motor operable when energized for shifting said valve from low pilot to low clean fire position, said second heat motor operable when deenergized into operative contact with the first heat motor to yieldably resist the action of said first heat motor and retard the rate of movement of the valve in opening direction under the influence of the said first-heat motor after the valve has opened substantially from pilot fire position. 1

4. The control device claimed in claim 3 wherein said sec-ond heat motor when energized is ineffective to resist the action of said first heat motor as said first heat motor shifts said valve to high fire position.

5. The control device claimed in claim 4 wherein. each heat motor comprises a strip of laminated thermostatic metal and an electrical resistance element in heat exchange relation therewith, a lost motion connection between the first and second heat motors whereby the second heat motor when energized acts through said lost motion connection on the first heat motor to shift said valve to low clean fire position, said lost motion connection being such that when the first motor is energized it moves from low clean fire to high fire position without acting upon said secondheat motor, and a one way driving connection between said first heat motor and said second heat motor effective when said second heat motor is deenergized and the first heat motor is energized as the first heat motor moves from substantially beyond pilot fire position to high fire position whereby said second heat motor yieldably resists and retards the opening action of said first heat motor.

6. The control device claimed in claim 5 wherein said one way driving connection comprises an abutment carried by one of said heat motors and extending toward the other heat motor, a stop upon which the second heat motor rests when deenergized, the length of said abutment being less than the distance between the first and second heat motors when each are deenergized whereby the first heat motor when energized shifts said valve substantially beyond low pilot position before said abutment on the one motor contacts the other motor.

7. The control device claimed in claim 6 wherein said abutment takes the form of an adjustable set screw extending from said second heat motor toward said first heat motor.

8. In a control device adapted for regulating arsenal,

ifrom 110w pilot to lowclean fire position, a stop against which said "second heat motor rests when cdeenergized, a bar carried by the second heat motor and having a projection underlying the 'firstxheett motor, saidzprojection contactingthe underside of said first heat motor to'flex the TfirstJheat motorin valve opening direction when thesecond heat motor is energized and .fiexes in valve opening direction, and an abutment carried by the second heat motor and projecting toward'saidfirst heat motor, said abutment engaging vsaid firstheat motor after thefirst heat .motor has moved substantially from low pilot position when the secondheat motor is deenergized and thefirst motor is energized.

, 9. In a control-device adapted for regulating the -supply of liquid fuel to a liquid fuel burner :comprising a casing having a chamber for liquid -.Iuel andanoutlet from said chamber, a metering valve for regulating thefiow of fuel through said outlet, first and second heat motors each'comprising a warpable laminated thermostatic metal strip and an electric resistance element in heat exchange relation therewith, said first heat motor operable when energizedto shift said valve from pilot to high fire position, said second heat motor operable when energized for shifting said valve from low pilot to low clean fire position, a stop against which said second heat motor rests when deenergized, said first heat motor having two projections on its free end, a bar fixed on the second heat motor, the lower end of said bar contacting the underside of said first projection when the second heat motor is energized and .the first heat motor is deenergized to flex the first heat -motor to low clean fire position, the second projection on said first heat motor when the latter is energized contacting the deenergized second heat motor whereby the deenergized second heat motor yieldably resists opening movement of the first heat motor after the first heat motor has moved substantially beyond low pilot position.

10. In a control device adapted for regulating =the-supply of liquidfuel to a liquid fuel burner comprising a casing having a chamber for liquid fuel and an outlet from said chamber, a metering valve for regulating the fiow of fuel through said outlet, firstand second heat motors each comprising: a 'warpa'bl'e laminated thermostaticrmetal strip and an electric resistance :elementiinsheat exchange relation therewithgsaidfirst heatmotor operable when energized :to shift said valvejifrom 'pilot itOLhlgh fire rpositionpsaid :second heatimotor operable when energized for "shifting :said :valve from ilOW pilot :to low :clean 5 fire position, :a :stop against'whichrsaid: secondheat motor; rests when deenergized, a driving connector pivotedato the endsof the one-of saidiheatrmotorsuandrhaving ;aprojection whichslidabl-y engages :a. slotted: ear

in-:theend oftherother heat motor whereby when fthe first heat'motorzis 'energized'the'ideenergized secondheat motor acts :through the connector .to.:-yieldab1y resist opening movement of the first --motor and whereby when'the second motor 11s :energized 1 and the first motor deenergizedsaid second motor: acts through-said connector .to flex the first=motor -tolow clean fire position.

.11. E'Ina control device adapted-for regulating 'the supply-of .liquid fuel .to a liquid fuel burner comprising acaSing'haV-ing a chamber forliquid fuel and an outlet from-said chamber a metering 'valve for regulatingthe flow-of fuelthrough said out-let, first and'second heatmotors each-comprisingawarpable laminated thermostatic metal strip and an electrioresistance element in-heat exchange relation therewith, said first-heat motor operable-when energized toshift-saidvalve from pilot to high fireposition, said secondheat motor .operable -when energized forshifting said valve fromlow pilot-to lowclean fire-pQsitiom-a stop against which said second heat motor rests when deenergizedthe free ends of each of said motors being of a bifurcated U form, lawconnector in theform of adouble cross :extending between the bifurcated .ends of said heat motors .and having thelupperhand. lower cross. members. positioned respectively within the U-shapedends of said motors with a'lost-motionbetween the U ends-and vthe cross bars whereby when the ,first motor is energized and thesecondmotor deenergizedthe second motor yieldablylresists opening movementof the first motor after the firstlmotor has moved-substantially beyond low fire vposition and whereby whenthe first motor is deenergized andsaidsecond motor is energized said second motor 'fiexes ,said first motor to low clean fire position.

FREDERICK HSHUNTLEY.

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

UNITED STATES PATENTS Number Name Date 2,369,739 Johnson 'Feb.' 20,1945 2,416,766 Miller Mar. "4,1947

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