US2491201A

US2491201A - Dual firing rate oil burner of the pressure atomizing type

Info

Publication number: US2491201A
Application number: US43826A
Authority: US
Inventors: Terrence C O'donnell; Joseph A Logan
Original assignee: Gilbert and Barker Manufacturing Co Inc
Current assignee: Gilbarco Inc
Priority date: 1948-08-12
Filing date: 1948-08-12
Publication date: 1949-12-13
Anticipated expiration: 1966-12-13

Description

Dec. 13, 1949 T. c. o'DoNNELL ErAL $91,201

DUAL FIRING RATE OIL' BURNER 0F THE PRESSURE ATOMIZING TYPE Filed Aug. 12. 1948 5 Sheets-Sheet l T v ATTOR EYS Dec., H3, 1949 T. c. 'DONNELL rAL 2,491,201

DUAL FIRING RATE OIL BURNER OF THE PRESSURE ATOMIZING TYPE 5 Sheets-Sheet 2 Filed Aug. l2. 1948 5 L uw T ML E NdA. M v WTHO man." dw A @.mmw.

Dec. 13, R949 r. c. ODNNELL ETAL 2,491,201

DUAL FIRING RATE OIL BURNER 0F THE PRESSURE ATOMIZING TYPE 5 Sheets-Shee't 3 Filed Aug. 12. 1948 A La.- w 1| l *m' N ffl/IIA w mil Dec. 13, 1949 T. c. o'DoNNELl. Er AL 2,491,201

' DUAL FIRING RATE OIL BURNER 0F THE PRESSURE ATOMIZING TYPE 5 Sheets-Sheet 4 Filed Aug` 12. 1948 Chiu@ f 22ml ATTORNEYS Dec. 13, 1949 T. c. 'DONNELL ErAL 2,491,201

DUAL FIRING RATE OIL BURNER 0F THE vPRESSURE ATOMIZING TYPE 5 Sheets-Sheet 5 Filed Aug. 12. 1948 N L 5 www T @man V9 H WOW dw N NN En mm T.

menudo. 1a, 1949 DUAL FIRING .RATE DIL PRESSURE ATOMIZING BURNER oF 'mit ma Terrence C. ODonnell, West Springfield, and- Joseph A. Logan, Gilbert &

Hadley, Mass., Barker Manufacturing Company,

orsto West Springfield, Mass., a corporation of Massachusetts Application August 12, 1

1 'rmsmvennon relates to en improved cual-nring-rate oil burner, .adapted for house heating service and of the type in which the two rates of now of atomizedoil are produced from a single pressure atomizing nozzle by varying the pressure of the oil fed to such nozzle.

The invention has for an object the provision in a pressure-atomizing burner of the general type disclosed in the Logan Patent No. 2,411,048, dated November 12, 1946, having within the burner structure a combustion chamber in which the greater part of the combustion occurs, of quickacting means for changing' the atomizing pressure to change the ring rate from a relatively low firing rate, lower than could be used with the same nozzle in an ordinary gun type burner, to a relatively high iiring rate, higher than would ordinarily be used with the same nozzle in the ordinary gun type burner, characterized in that an ample spread between the high and low ring rates can be hadvwith a smaller spread in atomizing pressures than could be had in an ordinary gun type burner; in that the maximum atomizing pressure is kept well within the limits of the capacity of the oil pumps usually used in g-un type oil burners, and in that a wide spread in ring rates may be had because the burner operation will not be limited by the size of the rebox in the heating apparatus since the combustion chamber is provided within the burner structure.

Assuming that the new burner is to be used for house heatingand that a differential of one half gallon per hour between the two ring rates is desired, and that the atomizing nozzle of the burner is, for example, one rated to give an oil burning rate of one gallon an hour at an atomizing pressure of about one hundred pounds per square inch, the way the burner of this invention operates is: the low iiring rate is obtained by lowering the atomizing pressure enough below the rated pressure of the nozzle to get an oil-burning rate of approximately .7 of a gallon per hour and the high rate is obtained by raising the atomizin'g pressure enough above the rated pressure of the nozzle to get an oil burning rate of approximately 1.2 gallon per hour. The difference between the rates is then a half a gallon an hour. Other things need to operate in the burner in relation to this dual rate operation. The oil rateneeds to be changed from one to another, 'as a. diierence A ber having a peripheral 94s, serial No. 43.326

s claims. Y (ci. 15s-.28) A .in the need for heatnoccurs. Asvsuch oil rate is' changed, the air rate needs to be changed to give an eicient air-oil ratio for burning and the way 'of changing the oil atomizing pressure to change the oil firing rate needs to be considered with relation to economy, simplicity, and the coordination of its action'with the action of the change in air rate all of which changes are preferably automatically controlled by thermostat action. One advantage aimed at is to provide a mode of operation which takes into account the desirability of making as few changes in construction of routine and available oil burner elements as will get the result in an inexpensive manner and utilize the mass-produced parts in the oil burner industry.

The invention will be disclosed with reference to the accompanying drawings, in which Fig. 1 is a side elevational view of an oil burner embodying the invention;

Fig; 2 is a front elevational view of the burner with parts broken away to show the air control shutter of the fan together with the-manual ad' justing means and the automatic actuating meansfor the shutter;

Fig. 3 is a sectional elevational view taken on the line 3-3 of Fig. 2;

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

Fig. 5 is a diagrammatical view of the oil supply system of the burner;

Fig. 6 is a sectional 5-6 of Fig. 3;

Fig. 7 is a wiring diagram of the electrical controls for the burner;

planview taken on the line Fig. 8 is a fragmentary sectional elevationalv view showing a' diierent form vof combustion chamber; and

Fig. 9 is a cross sectional view taken on the line 9--9 of Fig. 8.

Referring to these drawings, the burner includes within its structure a combustion chamber I (Fig. 3). This is formed by a tubular memwall 2 which is cylindrical, an inner end wall 3, which as shown is of frusta-,conical form, 'and an open outer end 4. In the peripheral wall 2 of the combustion chamber, there are a plurality of air inlet openings, which may as shown consist of a circular series of slots i, each opening into the chamber, as shown in Fig.

4, substantially tangentially to the inner surface .est

o! wall 2. These slots provide for the admission of air in whirling stream extending from one end to the other of the chamber I. There may also be a circular series 'oi similar air inlet openings 5 in the part-conical portion of the inner end wall 3. `Supported centrally from the inner end wall 3 (Fig. 3) is a tubular support 1, bearing on its outer end a nozzle 3, which is of the oil-pressure-atomizing type and is adapted to be connected at its inner end to a supply of oil under pressure. This nozzle is located near the inner end and coaxially of the combustion chamber and is adapted to emit a spray of atomized oil generally forwardly of the combustion chamber toward the open outlet end 4 thereof. A pair of ignition electrodes 3 (Fig. 4) also extend through and are insulated from the inner wall 3 with their inner ends properly located to ignite the spray emitted from nozzle 8.

The combustion-chamber-forming member described is telescoped into the outer end of an air supply tube I0, herein shown as cylindrical in form. The imperforate peripheral wall of tube I Ii is radially spaced from the peripheral wall 2, forming between them an air jacket II, which surrounds the entire combustion chamber I and with which the

air admission openings

5 and 3 communicate. The outer end of tube Ill is in turned to engage the peripheral wall 2 near its outer end and thereby close the outer end of the air Jacket' lI. The inner end of tube I0 is connected to receive air from a suitable fan.

The air supply fan is shown at I2 (Figs. 2 and 3) and it is mounted in a housing I3, formed in a casting I4, suitably supported, as from the iloor by a pedestal I5. In the lower part of casting I4 is a cylindrical passage I6 (Fig. 3) into the rear end of which fan I2 discharges. To the forward end of passage I6, the inner end of tube. I0 is secured, as indicated. The rear end of passage I6 is normally closed, as by a cover I1, secured by screws I8 (Fig. 6) so as to be easily removable to gain access to the interior of passage I6, when required. The air inlet to fan I2 is a circular Opening I9 (Fig. 2) formed in one end wall of its housing I3. Connected with and extending outwardly from this end wall are two laterally-spaced side bars 20, one of which is shown in full in Fig. 2 and both of which are indicated by dotted lines in Fig. 1. These bars 23 at their outer ends are connected with and support a circular ilange 2|. An air inlet control shutter 22 (Fig. 2) is movable toward and away from opening I9to vary the effective area of the air inlet to fan I2. This shutter has a screw thread engagement with a screw 23, which has near each end a smooth cylindrical portion. These cylindrical portions are slidably, -as well as rotatably, mounted one in a bearing 23', formed in the end wall having the fan inlet I3, and the other in a bearing 24, formed in the flange 2I. On screw 23 is a shoulder 25 adapted to abut the adjacent end face of bearing 23 and limit the inner axial sliding movement of the screw 23 and thereby determine the position of the shutter for low ring rate operation. Such position is variable and may be adjusted by rotating screw 23 and thus moving the shutter 22 toward or away from the air inlet opening I3. A rod 23, ilxed at one end to ilange 2I, extends in parallel 'and underlying relation. with screw 23, is slidably engaged with shutter 22, and serves to prevent the latter from rotating when the screw is turned. A screw 21 is threaded into dangle 2I adjacent screw 23 and is adapted to be engaged by a circumferentially grooved collar 2l,

4 tlxed on screw 23, for the purpose of limiting the axially outward movement of screw 23. The collar, when engaged with screw 21, determines the high tiring rate position of shutter-22. Buch position is variable and may be adjusted by turning screw 21.

The shutter may be automatically bel tween its high and low nring rate positions by means of a lever 23, the upper end of which is engaged in the groove of collar 23. This lever is received near its lower end in a vertical slot 33 in a block 3I, which is secured by screws 32 to one side wall of the casting I4. 'I'he lever 23 is fulcrumed on a pin 33 ilxed in said block. Also formed in this block is a cylinder 34, containing a piston 35, the rod 35 of which is pivotally connected at its outer end to the lower end of the lever 23. The outer end of cylinder 34 is closed by an annular plug 31 which slidably engages rod 35. Between this plug and the piston is a spring 38, which tends to force the piston inwardly in its cylinder and thereby yieldingly hold the shutter 22 in the`high firing rate position illustrated. When oil under pressure is admitted to the inner end of cylinder 34, by means to be described, the piston will be moved outwardly, actuating lever 29 to move the shutter 22 into its low ring rate position.

The fan I2 has its hub 33 xed to the shaft 40 of an electric motor 4I, which is secured to that end wall of the fan housing which lies opposite the air inlet I3. This motor also drives the pump'for supplying oil to nozzle 8. This pump, in the present case, is combined with a illter and pressure regulating valve, these elements being respectively located in the

casingparts

42, 43 and 44 (Fig. 1). These casing parts are all connected to and supported by a hub 45 (Fig. 2) which lits into a hole in flange 2| and is suitably fixed therein as indicated. 'Ihe drive shaft 46 of the pump passes through hub 45 and is ilxed to the driven element 41 of a centrifugal clutch, the driving element 43 of which is connected by a ilexible coupling 43 to the hub 33 of fan I2. The shutter 22 has a central opening to freely receive the clutch element 41. This clutch may be like that of U. S. Logan Patent No. 1,985,934, dated January 1, 1935, and is used for the purposes fully set forth therein. 'I'he arrangement provides for starting the pump after the fan, and only afterrthe latter has attained high speed, and for stopping the pump before the fan, and while the latter is still revolving at high speed.

The oil supply system in its entirety is shown in Fig. 5 together with the means by which the ring rate of nomle 3 may be changed by varying the pressure at which the ou is fed to the nozzle 3. 'I'he pump in this case consists of a pair of intermeshing gears 55, both of which are housed in the casing part 42 and one ot which is xed on the described shaft 45. The intake of the pump is connected by a diagonal passage 5I to a chamber 52, formed in the upper part of the hollow casing part 43. In the lower part of the latter is a filter chamber 53, containing illters 54. The lower end of chamber 53 is connected to a pipe 55, adapted to connect with an oil supply tank (not shown). Oil is drawn up through pipe into chamber 53, passes through the nlters 54 and thence into chamber 52, from which it ows by passage 5I to the pump. The latter forces oil outwardly through a passage 55 into a lower chamber 51 formed in the hollow casing part 44. In chamber 51 is a cut-oi valve 53, mounted on the lower end of a cylindrical member 53, which is ilxed to and depends from interior of member 8| above the seat valve 58. The upper and flanged end of belas'emi 6 l on from-chamber u t6 manche space mund the lower and closed end of a bellows 88. The member I8 is slidable in a tubular member 8|, which upstands from the base of chamber 81. Radial holes 82 in member 8| below member 58, enable oil to ilow from c amber 51 into the of cut-oi! lows 80 is held against an annular shoulder 58 by a spring 84, acting between the cover 55 and a washer 88, bearing on the flange of the beilows. Within the bellows and acting between theclosed end thereof and a spring seat 81, which is adjustable by a screw 88 in'cover 55, is a spring 88. -When the pressure of the pumped oil reaches a predetermined value, say for example 45 pounds per square inch. the bellows 80 will rise upwardly enough to allow oil to i'iow out of chamber 51 through radial holes into the outlet passage 1 0, which is connected by a pipe 1| to the nozzle support 1 and thus to nozzle 8.

The bellows 50 also controls a by-pass valve consisting of the cylindrical member 58, the tubular member 8| and a recess 12 in one side of member 58. This recess 12 is initially covered by the inner wall of member 8| as shown. However, when the pressure o i the pumped oil reaches another and higher predetermined pressure, say for example 50 pounds per square inch. the bellows 80 will have risen far enough to lift the recess 12 above the upper end of member 5|. Then some of the oil in chamber 51 will enter recess 12 and pass by way of a connecting passage 18 in member 58 into the interior of bellows 60 and thence into an upper chamber 14 formed in casing part 44. Oil iiows from chamber 14 through a passage 15 into a by-pass chamber 16 formed in a casing part 11 located between the parts 48 and 44. The by-pass chamber 16 is connected by a pipe 18 to the inlet of a two-way valve 18. This valve, shown diagrammatically in Fig. 5, has a liquid-receiving chamber, which is formed within a tube 80 of non-magnetic material and which is closed at opposite ends except for outlet passages 8| and 82. A valve 88, of magnetic material and located inside tube 80, is held by a spring 84 -against one end seat to close the outlet 82. A

solenoid 85 encompasses tube 80 and is operable, when energized, to move valve 88 against spring 84 into engagement with its other seat to close the outlet 8| and at the same time open outlet 82. I'he latter is connected by a pipe 88 to suction pipe 55. Thus, when the solenoid 85 is euergized, by means to be later'described, the liquid flowing past the by-pass valve 12 may flow,

without restriction, by way of pipe 18, tube 80,

passage 82, and

pipes

85 and 55 back to the suction side of the pump. The by-pass valve 12 will -then determine the maximum pressure of the oil that is supplied to nome 8 and the cut-off valve 58 will determine the minimum pressure. The f maximum pressure, thus determined is for the low firing rate of the burner.

' To secure the relatively high rate of flow of oil vto nozzle 8, a second by-pass valve 81 is provided in a chamber 88 formed in a casing 88. The described outlet 8| of valve 18 is connected by a pipe 80 to chamber 88. Valve 81 is mounted on the lower end of a cylindrical member 8|, fixed to and depending from the lower and closed end of a bellows 82, which is held in place in casing 88 in the same way as the bellows 80 and which is forced downwardly by an adjustable spring 88 to hold the valve 81 toits seat. Member 8| is vertically slidable in a tube 84, which has radial openings 85 above the seat of valve 81 to allow 88, which is connected by a controls an outletpassage pipe 81 to lsuction to open at a much valve 81. This valve pipe 55. Valve 81 is adjusted higher pressure than the first bil-Dass valvl1 say us' for example 150 pounds per square inch.` when the solenoid valve 88 is positioned as shown, the second by-pass mum pressure of oil fed to nozzle to secure the highrate of ilow. l

As the rate of now of oil fromnozzle 8 is varied, the rate of flow of the air for combustion must be spring 88, acting through lever 28, tends to hold the air shutter 22 in position for the higher rate of air flow. The piston 85 is moved by oil pressure into position for the lower rate of air flow. This is accomplishedunder the control of a second solenoid valve 88, similar to valve 18. The solenoid 88 moves a valve |00 of magnetic material, located within a non-magnetic tube |0I. away from one end seat and into engagement with the other. A spring |02 normally holds valve |00 in the illustrated position, in which it closes an vinlet passage |08, which is connected by a pipe |04 to the nozzle supply pipe 1|. The

move valve |00 to closeY inlet |03 and open the passage |06, which is connected by a pipe |01 to suction pipe 55. Thus, oil will be drawn out of cylinder 84 to enable piston 85 to be moved back by spring 88 into its illustrated position.

The combined pump', filter, cut-oft' valve and first by-pass valve are shown in Fig. 5 reversely from Fig. l, as if taken on'the line 5-5 of Fig. 2.

Fig. 5 is to a considerable extent diagrammatical and does not show all the parts in their actual locations. Fig. l, however, locates all the parts,

including the pipe connections, as they actually are in the burner. The valve casing 88 is secured by screws |08 to the wall of air passage near the rear end thereof. The

solenoid valves

18 and 88 are mounted in the block 3| below the cylinder 84. These vvalves are standard articles available in themarket and they are shown only diagrammatically herein but this will suillce for an understanding of their functions. The oil pipe 1| extends through a recess in the cover i1 into the rear end of the air passage 46 and thence forwardly in the latter and tube |0 (Fig. 3) to connect with the rear end of the tubular support 1 for nozzle 8.

Referring now to some of the details of the exemplary burner, the combustion chamber l (Fig. 6) is supported at its forward and outlet end 4 by having its peripheral wall 2 rest on the nturned annular flange |08 of air tube |0. Suitably fixed in hubs formed on the rear side of inner end wall 8 are two laterally-spaced rods H0, which extend rearwardly in air passage I6 and terminate spark electrodes 8 are mounted in insulators ||8,

valve 81 will control the maxiproportionately varied. As described, the

7 which in turn are adiustably secured in the support ||2. The ignition transformer ||4, indicated in part in Fig. 6. is suitably xed to an outer wall of passage I8 with its high tension terminals I| extending into such passage-(see also Fig. 3) and being connected by wires I I9 to the electrodes 9. When the cover |1 is removed. the ends III of rods I|0 may be drawn toward each other out of their respective holes and then the rods may be pulled rearwardly in the air passage Il carrying with them the combustion chamber with nozzle 9 and electrodes 9in assembled relation thereon for inspection, adjustment or repair. The air shutter 22 sheet metal cover I I1 engaging at one end with the periphery of ange 2| and at the other end with the periphery of a flange I I9 on fan housing I3 and is suitably secured to such flanges (Fig. 1). The cover I l1 has a plurality of air inlet openings ||9 therethrough.

A typical form of control system for a househeating oil burner is shown diagrammatically in Fig. 7. A room thermostat switch |20 is connected in series with the secondary |2| of a step-down transformer and the coil |22 of a relay by means of Wires |23, |24 and |25. The primary |26 of this transformer is respectively connected by wires |21 and |29 to the supply wires |29 and |30, which lead from a suitable source of electricity, such as a 115 volt A. C. circuit. The relay coil |22 is adapted when energized to close a switch |3|, one terminal of which is connected by a wire |32 to supply wire |29 and the other terminal of which is connected by wires |33 and |34 to one terminal of motor 4|. The other terminal of the latter is connected by a wire |35 to the other supply wire |30. The primary |36 of ignition transformer |I4 is connected by wires |'31 and |39 to Wires |34 and |35, respectively. The secondary |39 of transformer ||4 is connected by the described wires IIB to electrodes 9. When switch |3 closes on a call for heat, it starts the burner` motor 4I and energizes the ignition transformer ||4 to produce sparks between the electrodes 9. Such is a simplilied and conventional illustration of the usual control for a house-heating burner. The diagram omits the various safety devices, which are usually used in conjunction with such a burner to stop it on failure of combustion and in the event of various other emergencies. It is understood that any or all such usual safety devices may be used in the present control system but, since these devices are old and 4well known, they have been omitted to avoid needless complications in the disclosure.

The

solenoids

95 and 99 may be controlled in connection with such a control system in the following manner.- These solenoids are connected in parallel to wires |40 and I'4I. Wire |40 connects with one terminal of a tiring-rate control switch |42, the other terminal of which is connected by a wire |43 to wire |33. The wire |4I is connected to supply wire |30. Whenever, the switch |42 is closed, the

solenoids

95 and 99 will be connected so as to be energized when th'e switch |3| closes to start the motor 4| and the solenoid valves 93 and` |00 will then be operated to provide for the lower oil pressure and smaller air inlet opening required for operation at the low firing rate. If switch |42 is open, the solenoids will not be energized, when the burner starts, and the valves-93 and |09 will remain positioned as shown for the higher oil pres- (Fig. 2) and its adjusting means are usually enclosed by a part-cylindrical sure and larger air inlet opening needed for operation at the high firing rate. The switch |42 may be operated manually or automatically as desired. It may be, and desirably is, a thermostat switch, responsive to the temperature at some location, where the temperature will be indicative of the need for low or high nring rate operation. It may, for example, be responsive to outdoor temperature.

In Figs. 8 and 9. there is shown another form of combustion chamber. 'I'his chamber, designated |45, like the chamber is formed within a cylindrical .wall |43. having a frusto-conical inner wall |41 at one end and being open at the other end. As in the nrst described construction, most of the air for combustion is introduced through the peripheral wall 49 around the spray of atomized oil emitted from the nozzle 9 but the air-admission openings, in this case, are radiallydirected and in the form of many small and closely-spaced perforations |49 distributed over the entire area of wall |45. Similar air admission openings |49 are provided in end wall |41. The nozzle 9, in this case, is located inside a tubular shield |50, fixed to the end wall |41 and having on its inner end an inturned frusta-conical iiange I5I with a central opening through which the oil spray emitted from nozzle 8 enters the combustion chamber in a direction generally lengthwise thereof. The tube |50 is spaced from the nozzle support 1 leaving a passage for air to dow into the combustion chamber, such air being deflected by flange |5|' inwardly to meet the oil spray and entering with the latter through the central opening. The ignition electrodes 9 extend through and are insulated from the end wall |41 and their inner ends are properly positioned to ignite the combustible mixture. 'Ihe insulators |I3 for electrodes 9 are mounted in a support |52 ilxed to tube |50. This combustion chamber |45 is telescoped into an air supply tube |53, as before, forming an annular air jacket |54 around the combustion chamber. This jacket communicates at its inner end with the air passage |9 from fan I2 and at its outer end is closed by an annular ring |55, fixed to tube |53 and supporting the outer end of the combustion chamber. The inner end of the latter may be supported by a plurality of pins |59 (Fig. 9).

In the air jacket |54 is a baille, consisting of an annular ring |51 having its'inner periphery slidably engaged with the outer periphery of wall |49 and its outer periphery slidably engaged with the inner periphery of tube |53. In this baille are a plurality of air openings |59. The position of this bafe in the air jacket may be adjusted by means of a screw |59, rotatably mounted at its outer end in a ring |55 and at its inner end in a lug |60, fixed to tube |53. The screw has a threaded engagement with baille |51 to move the latter longitudinally of jacket I 54, when the screw is turned, and this may be done by a knurled knob IGI, xed to the inner end of the screw and projecting through a slot in tube |53 so that it may be actuated from outside the leftter. 'I'his baille enables the size of the :lets of air, .which issue through some of the perforations |43, to be varied with respect toilets of air which issue through other perforations |49. The perforations |49, which are located to the right of baille |51. receive air only by way of the bame openings |59. the aggregate area of which is substantially less than that of Jacket |54. Because of the restriction of air flow by baille |51,

einer I the air issuing from the perforations |40, which arelocatedtotherightofthebafile,willbeats less rate and pressure than the air issuing from the perforations |48 which are located tothe left of the baille The baile 181, if not needed in any particular case, can be rendered inoperative by moving it to the front end of jacket |04 until it abuts ring |00.

'I'he operation of the case the switch |42, is moved to the proper position for the tiring rate desired. As shown, this is done automatically by the thermostat element of the switch but obviously the switch may be manually operated, if desired. Assuming that the switch |42 is open as shown, the burner will, when started, operate at the high tiring rate because neither the solenoid 85nor the solenoid 08 will be energized, when the burner motor switch l3| closes on a demand for heat, evidenced by the closing of room thermostat switch |20. When switch |3| closes, the motor 4| starts. driving with it the fan l2 and, after the motor and fan have acquired considerable speed, the clutch 41, 48 will engage to drive the oil pump 80. Air flow through tube A before oil flow from the nomle 8. The air will be supplied at the high rate because the air shutter 22 will be held by spring 30 in the high rate position shown in Fig. 2. Also the cylinder 34 is connected, as shown in Fig. 5, by pipe |05, tube |0|, passage |08 and pipe |01 to the

suction pipe

5,5 of the pump, thus supplementing the action of spring 38 in holding shutter 22v in the high rate position. Oil will be supplied by the means shown in Fig. 5. The cut-oil valve 58 will open, when the minimum oil pressure has been attained, and oil will flow through conduit 1| and support 1 to nozzle 8. As the pressure of the pumped oil increases, by-pass valve 12 will open allowing some of the pumped oil to iiow by way of passage 13 hollow .bellows 60, chamber 14, passage 15, chamber 18, pipe 18, tube 00. passage 0| and pipe 80 into the chamber 08 of the second by-pass valve 01, which will not open until the maximum pressure needed for high nring rate operation has been established. The second by-pass valve then opens to allow excess oil to pass through pipe 01 to pipe 55 and thus to the suction side of the pump. The oil spray from nozzle 8 (Fig. 3) is emitted into the combustion chamber and there mixed with air, some entering through thc slots I in the inner end wall 3 of the combustion chamber but the larger part entering through the slots in the peripheral wall 2 of the chamber. The combustible mixture is ignited by a spark produced between the electrodes 8 and burns to a large extent within the limits of the combustion chamber. The iiame does not extend very far beyond the open outer end 4 ofthe chamber, say for a distance about equal to one `quarter of the length of the combustion chamber. This distance that the flame extends from the open end of the chamber is so short that it is unnecessary to build a combustion chamber in the heating apparatus, which is to be fired by the burner. as is necessary in the case of the ordinary gun-type burner. It might be desirable to place a refractory brick in front of the nozzle against the wall toward which Y the flame is directed. but nothing more would be required in the ordinary installation. The burner will ordinarily continue to operate at the high rate until the demand for heat is satisfied. when the motor 4| (Fig. '1) is 'stopped and the ignition invention will next be' described. The :tiring rate control device, in this lo and Jacket will be started l0 switch |0|, caused by tne opening of the room thermostat switch |28.

Assuming now that the switch |42 is set for low iiring rate operation. when the switcn |3| 5 closes on a demand ror heat irom tne burner,

the motor 4| will be started and tne igmtion transformer ||4 energized as beiore, but in addition, botn solenoids an and sa will be energized because switch |e2 is now closed. Thus, when the burner starts, the valves 83 and Illu. will be vmoved by the solenoids 85 and 8s into their extreme right hand positions. The outlets 8| and |08, which were formerly open for the high ilring rate operation, will now be closed and the 1'5 previously-closed passages 82 and |03 will be opened. The cut-off valve 58 will open at the minimum pressure, as before, and allow flow of oil to nozzle 8 and, after the pressure increases slightly, the first by-pass valve 12- will open and allow some ofthe pumped oil to flow directly back toward the suction side of the pump. Such oil flows by way of passage 13, bellows 60, chamber 14, passage 15, chamber 18 and pipe 18 into tube 80, -as before, but this oil now has to leave through the outlet 82, which is connected by pipe 85 to the suction pipe 55 of the pump. Oil is thus supplied to nozzle 8 at the low pressure for low ring rate operation. At the same time that oil iiows to nozzle 8, some oil is admitted through pipe |04 and passage |03 into the tube |0| and passes out through pipe |05 to cylinder 34, forcing piston to the right and causing air shutter 22 to be moved into its low rate position. The combustible mixture is ignited, as before, and op- 35 eration of the burner at the low ring rate ordinarily continues until the demand for heat is satisfied, when switch |3| opens to stop motor I, 4| and deenergize the ignitiol'ii"y transformer ||4 and the

solenoids

85 and 89.

A change from one firing rate to another can occur while the burner is operating. The firing rate control switch |42 can move from open to closed position or vice versa, whenever desired, or whenever the demand, which inuences the 45 thermostat switch |42, changes. A change from one firing rate to another can occur without any interruption in the flow of oil to nozzle 8. Oil is supplied to the nozzle as soon as the cut-oi! valve 58 opens and, so long as the minimum preslo sure is maintained, this valve will remain open and allow oil to reach the nozzle. If the burner is operating at the low ring rate and a change to the high iiring rate is made, the valves 83 and |00, which were previously heldin their right hand positions by the energized

solenoids

85 and 89, are moved back by springs 84 and |02, respectively, into their illustrated positions. Valve 83 now directs the oil, which is by-passed from the rst by-pass valve 12, into passage 8| and 6|) pipe 90 and thence into the chamber 88 of the .i second by-pass valve 81. The oil pressure will now increase until the high ring rate pressure is attained, when valve 81 will open, as before described to maintain such pressure constant.

88 But the oil flow to the nozzle 8 is not cut-of! during the transition from the low to the high firing rate. The oil supplied to nozzle 8 gradually ini creases in pressure. The valve |00 will now connect cylinder 34 by way of pipe |05, tube |0|,

passage |08 and pipe |01 to the suction pipe 55 of the p p. The spring 38 will now move air shutter 2 into its high rate position.

Assume now that a change from high iiring rate operation back to low firing rate operation is transformer I |4 is deenergized4 by the opening of 1l desired. The tiring rate control switch |42 will Ill close. causing the

solenoids

85 and 98 to be energized, drawing valves I3 andl |00 into their extreme right hand positions. Valve 83 will then cut oiT the flow of oil which is by-passed by valve I2 to the second by-pass valve 81 and direct such by-passed oil through outlet 82 and pipe 86 directly into the suction pipe 55. The oil supplied to nozzle 8 will rapidly decrease in pressure until it reaches that for which the rst by-pass valve is set. 'Ihe valve |00 enables the cylinder 34 to be supplied with oil under pressure to cause air shutter 22 to be moved into its low iiring rate position. The transition from high to low oil pressure does not interrupt the ow to nozzle 8.

The operation of the burner shown in Figs. 8 and 9, is the same as that described except that the air is introduced into the combustion chamber |45 by way of a large number of perforations |48 and |49 in the peripheral wall |46 and inner end wall |41, respectively. The air is fed through these walls in jets which are directed radially of the combustion chamber from a large number of angular positions closely spaced all around the entire circular extent of the spray and also closely spaced along the length of the spray. 'Ihe jets through the peripheral wall |46 are at right angles to the axis of the spray while those through the end wall |4'Ivare at an acute angle to such axis and have a component acting in a forwardly direction along the spray.

In the case of the Fig. 3 arrangement, the air is introduced through the peripheral wall 2 of the combustion chamber in whirling streams which surround the spray and to a considerable extent keep it from impinging on the wall of the combustion chamber and in any event keep such' wall within reasonable temperature lmits.- In the Fig. 8 arrangement, the radial iets of air have a similar eilect. In each case, the eiort is to restrain the flame, as much as possible, from impinging on the walls `oi the combustion chamber and to keep such walls relatively cool. In each case also, there is a lcontrolled distribution of the air-along most of the length of the llame, which results in better carburetion than could be had by the ordinary method of blowing the air from the open mouth of an air supply tube in a direction generally lengthwise along an oil spray produced by an atomizing nozzle located in such mouth. Particularly, where the nozzle is operated at a pressure much less than its rated pressure, the ordinary method of feeding air more or less lengthwise along the oil spray will not result in good carburetion because there is not emcient atomization of the oil and a full spray is not produced. It is necessary to compensate for the ineicient atomization of the oil'and this can be done with either of the combustion chambers shown. The llame is ted with air by Jets or streams entering through the peripheral wall of the combustion chamber and providing a well distributed feed of air along a substantial length of the llame within the chamber. Except for the described distribution of air to the combustion chamber, etlicient combustion could not be had when the nozzle is operated at much less than its rated pressure.

Assume as one speciiic example that the nozzle usedisratedtoproduceaiiowotatomized oil at the rate of one gallon per hour when operated at a pressure of 100 pounds. By the use of a combustion chamber of the general type described and the special air feed through the walls of such chamber, the nozzle can be operated at one half ofits rated pressur .orpoundatosecurea half gallon range l2 low ring rate of about .'I gallon per hour. Then by increasing the oil pressure to say 150 pounds,

a high rate of ilow of about 1.2 gallons per hourV can be produced. There is, it will be seen, a good range in theiiring rates available from a. standard one-gallon per hour nozzle. The example describedis conservative. It is possible to reduce the cil pressure to about 25 pounds mr square inch and secure a low firing rate of onehalf gallon per hour from this one particular size 01' nozzle. This will increase the firing range to .7 gallon. Generally the half-gallon range in firing rates suiiices for a nozzle of the one gallon per hour ji-ating. This particular size o1' nozzle is the smallest that is ordinarily thought feasible to use except under special conditions. It does not.y when used in the conventional way, enable a low enough rate of oil ow for the low iiring rate. It might perhaps be operated in the conventionalway at a pressure slightly under pounds per square inch but the diil'erence in rate oi flow produced would not be appreciable.

For 'any given rangeof ilring ratesdesired, the range of oil pressures necessary to produce the change in such rates from a nozzle of any given characteristics, increases rapidly as the low tiring 4rate is increased. The ilow from an oriilce of any given size varies approximately in proportion tothe square vroot oi the pressures used. In the example given, one-half gallon range is had from a nozzle rated to produce a iiow of one gallon per hour when operated at 100 pounds, by varying the pressure from 50 to 150 pounds per square inch-a pressure range of 100 pounds per square inch. It was shown that a pressure range of 225 pounds persquare inch is necessary to get the same range in iiring rates if the lowtiring rate is o ne gallon per hour. If the low ring rate islo'wered to one half gallon per hour by using oil pressure or about 25 pounds per square inch, the high ring rate can be one gallon per hour and the high pressure 100 pounds per square inch. Here, the range in oil pressures is only 'i5 pounds per square inch. This lastnamed example probably represents the lowest limit feasible. Itillustrates theA point that the lower the low ring rate, the less is the increase in pressure necessary to get the high ring rate with any given range in iiring rates. Starting at 25 pounds per square inch pressure, the prespounds per square inch for the in ilring rates; if the low pressure is 0 poundsv per square inch, the pressure range will be 100-pounds per square inch, and if the low pressure is 100. pounds per square inch, the pressure range is V pounds per square inch for the s'ame firing range.

The invention enables an ilring rate, lower than can be normally had with a pressure atomizin'g nozzle in a gun type burner; it provides for the change in ring rates by changing the pressure of the oil fed to the atomizing= nozzle and with a smaller spread in oil pressure than could be had from a pressure atomizing nozzle in a conventional gun type oil burner it'l keeps the maximum oil pressure within the limits of the capacity of the oil pumps usually used in gun type oil burners; and it provides, within the burner structure, a combustion chamber in which the greater part of the combustion occurs, so that the wide spread in tiring be had because the burner operation win not be limited by limitations of size of the s paratus for regulating the pressure of the oil supto said conduit and nozzle to set such apparatus to predetermirie a pressure for the oil supply to the nozzle substantially lower than the pressure for which its atomizing efficiently is predetermined, another valve-setting means interlocked with said first valve-setting means to alternately and only alternately set such apparatus to predetermine a pressure for the oil supply to the nozzle substantially higher than the pressure for which its atomizing eiciency is predetermined, whereby the regulating apparatus may be set for a firing rate lower or higher than said iirst-named rate, an air supplyjan, an air tube of the gun-burner type connected to receive the air from the fan, an adjustable shutter for the fan to determine the rate at which air is supplied to said tube, a second tube forming within it a combustion chamber and mounted in spaced coaxial relation in the air tube forming between it and the air tube a jacket, a closure for the forward end of the jacket, the rear end being open to receive air from the fan, the rear end of the second plied by the pump valve-setting means tube being partially closed and its front end be ing open, the peripheral wall of the second tube having openings therein for air to enter the coinbustion chamber from said jacket, said nozzle being positioned in the rear end of the combustion chamber to emit oil forwardly toward its open front end to mix with air supplied through the openings in the peripheral wall of the combustion chamber to compensate for lowered eiliciency of atomization at the low iiring rate, a power operated device to move said shutter to one predetermined position to secure a relatively low rate of air flow and provide for an eiiicient airoil burning ratio for the low pressure setting of said valve regulating meansv and to another predetermined position to secure a relatively high rate of air flow and provide for an efcient airoil burning ratio for the high oil pressure supply setting of said valve regulating means, and means interlocking said power device and said pressure-regulating valvev apparatus to cause the shutter to be moved to said low rate or high rate position whensaid apparatus is respectively set for said low or high pressur 2. In an oil pressure atomizing burner of the kind having an oil pressure atomizing nozzle, adjacent ignition means, power mechanism to pump oil through the nozzle at a predetermined constant pressure according toA adjustment, a power fan to supply air at a predetermined constant rate according to adjustment, and an air tube to direct air from its supply to meet the oil from its supply, the combination of a tube spaced within the air tube and forming a combustion chamber, the nozzle and the ignition means being positioned at the rear portion of the combustion chamber to project atomized oil lengthwise thereof, the forward end of the combustion chamber being open adjacent the forward end of the airvtube' and the space between said tubes being closed of! at such forward end while its rear end is open to receive air from the fan. shielding walls at the rear end oi' the combustion, chamber to direct air\ from the fan for the most part to the space between the tubes, and thence tangentlally through slotted openings into the combustion chamber to meet the atomized oil along its length in the form of a forwardly pressed whirling layer of the air-supply, adjustable pressure-regulating valve means for regulating the pressure of the oil supplied by the pump to said nozzle and thus the pressure at which oil is atomized, quick-acting power-operated means for changing the adjustment of said valve means from one constant predetermined rate to a substantially different one to change the oil burning rate of the burner from a relatively low rate to a relatively high rate of substantial dierence due solely to the change in the amount of the atomizing pressure, and interlocked operating means between the pressure changing means and said air supply shutter to cause the latter to take a position to correspond with a change in atomizing pressure.

3. In an voil pressure atomizing burner of the gun type for domestic heating and of the kind having a motor-operated air-supply fan and oilsupply pump, an air tube connected to receive air from the fan, an atomizing nozzle, a conduit connecting the pump and nozzle, and ignition means adjacent the nozzle for igniting the air and oil mixture, such as is generally adapted for operation at a single firing rate due to a predetermined size of nozzle which is rated lfor a predetermined pressure for atomizing oil to give -such iiring rate, the combination of additional elements for and some rearrangements of the elements of such a burner to convert it to a dual rate burner, comprising an automatic pressureregulating-valve mechanism for regulating the pressure of oil supplied by the oil pump to said atomizing nozzle, such mechanism having a hand-operable precision-adjustable device to predetermine a relative low pressure operation for such regulating valve mechanism and a second and similar precision device to predetermine a relative high pressure operation for such valve mechanism, quick-acting power means to set such mechanism in condition to automatically regulate the pressure of the oil as pumped for the low or the high pressure delivery to the nozzle, a shutter mechanism for the fan to determine a high or low rate of air supply for the burner operation, the latter mechanism also having two hand-operable precision-adjustable devices, one for its low air rate and one for its high air rate, said shutter mechanism having means to set it for one or the other of said air rates, such lastnamed means being actuated by and interlocked with the aforesaid quick-acting power means-so thatthe shutter is set for the high or low rate of air supply when said mechanism is respectively set for high or low pressur and means to compensate for the lack of atomizing efliciency of said rated nozzle when operated at a lower oil pressure than the nozzle rating, said last-named means comprising a combustion-chamber-forming inner tube built within said air tube in spaced and coaxial relation, saidv nozzle and said adjacent ignition means being positioned at the rear end of such combustion chamber, said inner tube forming the combustion chamber having air feed openings adapted to feedy the air to the oil in a whirling sheet extending around the com- REFERENCES CITED The following references are 111e of this patent:

of record in the Number 18 UNITED STATES PATENTS Name Date Powers May 27, 1924 Scheifele Dec. 25, 1934 Senmnger Apr. 9, 1946 Logan Nov. 12, 1946 Logan et al Mar. 15, 1949