US2405243A - Oil burner - Google Patents

Description

Aug., @9 E46., L F. SPEARE OIL BURNER Filedqune 19, 1944 2 sheets-sheet 1 Emma-wm@ JPM #f1 ATTOR N E Y S Aug, 6? NM26, l LyFQsPEARE OIL BURNER Filed June 19., 1944 A 2 Sheets-Shawl*l 2 ...m Y ...y um

' ORNE Patented Aug. 6, 1946 v OIL BURNER Leolyn F. Spearc, Westfield, Mass., assigner to Gilbert & Barker Manufacturing Company, West Springfield, Mass., a corporation of Massachusetts Application June 19, 1944, Serial No. 540,957

2 Claims.

This invention relates to improvements in oil burners of the so-called gun type, such as are adapted for use in residential heating and are started and stopped many times each day during the heating season.

A gun type burner utilizes a so-called mechanical or pressure-atomizing nozzle, located near the outlet end of a tube, through which the air for combustion is supplied by a fan, usually driven by an electric motor. The oil is supplied by a pump, also driven by the motor. Oil is admitted under the control of a cut-ofi' valve to the nozzle only after it has been placed under a predetermined minimum pressure suiicient for atomization. This pump is positive in action. Furthermore, it usually has aV capacity in excess of normal requirements for combustion and excess oil is bypassed after a certain predetermined maximum pressure has been reached. The fan, howevenis not positive in action. Consequently, when the burner motor is started, the pump will place the oil under atomizing pressure before the fan has established flow of air at proper pressure and velocity at the outlet end of the air tube. Poor combustion results and the smoky llame deposits soot in the combustion chamber and passes of the boiler. On stopping of the burner motor, the air flow drops c-if rapidly and before the cut-off valve closes, the rate of flow of air at the nozzle is too low for the proper combustion.

This invention has for its general object the provision of means for improving combustion conditions during the starting and stopping intervals of operation of a burner of the class described. A

The' invention has for one particular object to provide in a burner of the class described, means whereby flow of air at the desired pressure and velocity is established at the burner nozzle at an earlier time in the starting period and sustained for a longer time in the stopping period than has heretofore been possible in an ordinary gun type burner.

According to this feature of the invention, a bypass is provided from the outlet of the fan together with a damper to control the by-pass and the damper is arranged to open when the air supplied to the tube attains the required pressure and velocity. The shutter or air valve associated either with the inlet or outlet of the fan is adjusted to admit to the tube all the air that is needed for combustion when the fan is revolving at some speed less than its normal full speed, say for example, three-quarters speed. The damper is set to open at the required static pressure.

Accordingly, when the burner motor is started, the fan produces the desired flow of air at an earlier time in the starting period than heretofore and, after the selected predetermined speed has been exceeded, the damper opens and bypasses excess air, maintaining the pressure and velocity of the air supplied to the tube constant. Also, during the stopping interval of the burner the flow of air is maintained for a longer interval. As the fan slows down, the damper moves toward closed position and the air flow to the combustion tube is maintained at the proper pressure and velocity for a substantial part of the stopping interval. By fixing the predetermined speed, at which the damper opens and'closes, to correspond with that at which the oil cut-'olf valve opens and closes, good combustion conditions can be had during the starting and stopping intervals. Y

As a desirable additional feature, the invention provides an oil control valve, such as an-electromagnetically operated valve, connected so as to open only when the damper in the air by-pass opens and to close coincidentally with the cutting off of current from the driving motor. This oil control valve insures that, on starting up the burner, oil cannot be admitted to the nozzle of the burner until air at properI pressure and velocity is being supplied to the burner nozzle and that, on stopping the burner, oil ow to the nozzle will be cut off before the pressure and velocity of the air supplied to the combustion tube decreases below the desired values.

The invention will be disclosed with reference to the accompanying drawings in which- Figs. 1 and 2 are small-scale side elevational and top plan views respectively of an oil burner embodying the invention; l

Fig. 3 is a fragmentary sectional plan view taken on the line 3 3 of Fig. 1 and drawn'to a larger scale;

Fig. 4 is a cross sectional view taken on the line 4 4 of Fig, 3;

Fig. 5 is a view taken similarly to Fig, 3 and showing a modication of the invention;

Fig. 6 is a cross sectional view taken on the line 6 6 of Fig. 5; and

Fig. 7 is a diagram showing electrical connections used with the form of burner shown in Fig. 5.

Referring to these drawings; the invention isy shown, by way of illustrative example,- in connection with a so-called gun-type oil burner of well known form. The combustion tube is shown at l (Figs. 1 and 2), fixed to the outlet end 2 of a fan housing 3, in which is rotatably mounted a fan 4, driven by an electric motor 5. As shown, the

3 outlet 2 is square in cross section and it is connected to the cylindrical tube I by a sec-tion 2', which changes from square to circular cross Section. The parts I, 2 and 2 provide an air-supply is shown at 8.. The outlet of the pump is connected by piping 9 to the nozzle support I0-and thus to nozzle 6. Interposed inthis;V piping is a unit II containing a cut-oi?v valve and' a by-pass valve of usual or any suitable form. The cut-ofi valve closes the outlet to the oil has reached a predetermined minimum to the fan and thus also driven by motor 5. The suction pipe for the pump.l

the burner nozzle Iiuntil pressure and the by-pass valve subsequentlyby- Y passes oil by way of a pipe I2, to any lsuitable point,` such as vthe tank or the suction sideof pump 1, whenever the oil reaches a predetermined maximum pressure.

The adjustment for varying the volume of air enteringtube I from the fan may be elected in any suitable way and on the discharge as well as on the intake side of the fan. In this particular case, the adjustment i onthe intake side. Fixed to one side of theifan housing is a casing i3 affording a chamber I4v in communication with the inlet side of the fan. Openings I5 provide for communication of the chamber I4 with the atmosphere. A Valve or damper I6 is mounted for adjustment axially of shaft 'I' on which it is slidable, and controls the amount of air tha-t can enterchamber I4 by way of openings I5 to. the fan. As shown, theY hub ofthe damper is threaded on a screwy I1, having its outerI end. rotatably mounted in theend of casing i3 and itsrinner end similarlymounted in a .lugA I1', depending from the top of the casing I3'.` The screw is heldagainst axial movement, as indicated in Fig; 3.

The oilis ignited by spark electrodes I8, mounted, in insulators I9, in a member- 2t which also supports the member It*Y and nozzle @from tube I1.

This invention provides fora second and venting outlet for the air-supply conduit. Conveniently, this venting outlet may connect with the intake sidev of the fan, thereby providing a bypassbut this is not essential. is constructed toprovide a chamber 2l 'above the outlet 2 and an opening 22' by meansV of which communication between the outlet 2 and chamber 2l may be established'.v The chamber 2l is'connectedloyY a tube 23Y to the inlet chamber- I4v at a location between the fan inlet and they innermost position which damper IS is likely to assume. Controlling the openingY 22 is a valve or damper 24 mounted on a pivot 25 located ofi centerl as shown.. A removable cover 26 provides-access to the chamber 23. Fixed to the damper is an arm 21 on which is adjustably mounted aweight 28, tending-to hold the damper-- closed. Ailug 29 on one end of the damper cooperates with the base wall of" chamberl 2 Il as a stop toprevent counter-v clockwise movement (as viewed irl-Fig. 4s) beyond the closedv position shown.

The damper-or air inlet valve I6 is adjusted to admit all the air that is required, for combustion while the ian is revolving at some. predetermined speed less than itsv normal and full speed, such for example as three-quarters speed. The-weight 28 is adjusted so that the damper 24rwill openl after the desired predeterminedY static pressure-- of the air in the combustion tube has beenvat- The ian housing` ,-1

- up the necessary oil pressure,

flow decreases at all'. The

tained. When the fan is revolving at full speed it would supply air at a greater rate of flow than is needed except for the by-pass valve or damper 24 which opens as much as is required to maintain the pressure and velocity of the air in tube I substantially constant at the desired values. In .this-way, it is insured vthat air,` will be flowing through the tube I past the burner nozzle at the desired rate after the motor reaches the selected predetermined speed and thereafter during the remainder of the starting interval, as well as during the normal running interval and during the initialA part of the stopping interval. According to former practice, maximum air flow was not reached until the'fan attained full speed. With the present invention maximum air ow is secured when` the fan reaches '75% of its normal speed and, of course, an even lower speed may be selected, if desired. The object is to get full air flow at or about the time that the oil cut-off valveopens and allows nozzle 6 to emit a spray of atomized oil. The particular speed at which damper 24 opens is a matter of choice, and may be-variedas is necessary or desired.

As an added feature of reiinement` to. secure and insure closer coordination between proper oil flow and airflow, a valve S is interposed in the oil piping 9 between the cut-oir valve and nozzle 6 and is suitably arranged to prevent flow of oil to nozzle B until the proper flow of air has been established duringthe starting interval of operation of the burner and before the air flow drops below the desired rate during the stopping interval of operation of the burner. The valve may for example, be al solenoid valveopening only when the solenoid is energized and remaining open for so longas `the solenoid remains energized. The damper 24 may serve, as indicated, to move a mercury tube switch 3I from openl to closed position as the damperopens and from closedto open position as the damper closes. The electric circuits are indicated in Fig. 7. The burner vmotor 5 and the ignition means 40 are connected in parallel in a circuit including the wires'35 andv 3S. The room thermostat switch 32y is interposed between the wires Skand 3B'. The wires 34 and 35 are adaptedv for connection to a suitable source of electricity. The solenoidr valve S0 is in a seriesl circuit which comprises the Wires 31, 38 and 39 and is shunted across the wires 3:5 and 36. The room thermostat switch starts and stops theburner motor in the usual way. Energization of the burner motor will start thepump and fan-but, irrespective of when the pump builds there will. be no.r emission of oil fromnozzle S unless and until flow or" air at the proper pressure and velocity,v and thus at the proper rate, has been established in tube I. Then, and then only, will damper 2.4' open. The closing of switch 3l and the opening of oilvalve Sil-is conditioned on the opening of damper 24;- When the burner motor is deenergized, the oil valve 30 will immediately close and cut 01T- therflow of oil to the nozzle before the air continuance of air flow afterroilY flow is-an advantage becauseofy the scavengingeffect.

The control of the oil howy by means cuor'- dinated withA the byi-pass Valve 24. may beraccom plish'ed': in any other suiiableway.` and neednot necessarily. be conned tothe use of a solenoid valve locatedn as shown. The important. thingv is to prevent the oil from issuing. from the. nozzle except-at vsuchtimestas air at. properpressure Y andvelocityis availableat the outlet of tube I1.

It will thus be seen that the invention provides for the improvement of combustion conditions during the starting and stopping intervals of operation of a burner of the type described. With the use of the oil valve, the desired results may be insured so that combustion cannot occur except when there is both a proper ow of air and a proper ow of oil. The burner may be adjusted for a higher CO2 reading, and thus for materially increased efficiency, when the improvements of this invention are used.

It should also be noted that the coordinated control of oil and air offers insurance against operation of the burner under any conditions which cause less than the normal supply of air. If the air openings I5 become stuled up with dirt, lint or anything else, or if for any other reason, air at the desired rate cannot be supplied to the combustion tube, then the oil valve 3l) will remain closed and prevent combustion.

I claim:

1. In an oil burner, a casing providing a fan housing having intake and discharge openings and a conduit communicating at one end with said discharge opening and having an outlet at its other end, a fan in said housing between said openings, an oil-atomizing nozzle in said conduit, an oil pump connected to supply oil to said nozzle, a motor for driving the fan and pump, said conduit having a second and venting outlet located between the fan and nozzle, a valve for the second outlet for opening and closing the same, and a valve for one of said openings adjustable to vary inow of air to said conduit and adjusted to admit all the air required for combustion when the fan is revolving at a predetermined speed less than its normal speed and the rst-named valve is closed, said first-named valve closing and opening automatically accordingly as the fan revolves below or above said predetermined speed respectively.

2. In an oil burner, a casing providing a fan housing having intake and discharge openings and a conduit communicating at one end with said discharge opening and having an outlet at its other end, a fan in said housing between said openings, an oil-atomizing nozzle in said conduit, an oil pump connected to supply oil to said nozzle, a motor for driving the fan and pump, said conduit having a second and venting outlet located between the fan and nozzle, a valve for the second outlet for opening and closing the same, a valve for one of said openings adjustable to vary iniiow of air to said conduit and adjusted to admit all the air required for combustion when the fan is revolving at a predetermined speed less than its normal speed and the first-named valve is closed, and adjustable means for holding the rst-named valve closed until the air reaches a predetermined pressure.

LEOLYN F. SPEARE.

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