US2347842A - Oil burner and system - Google Patents

Description

May 2, 1944.

c. L. RAYFIELD 2,347,842

OIL BURNER AND SYSTEM Filed Sept. 27, 1939 4 She etsS1 1eet l CHARZES' L. RA man y 1944- c. L. RAYFIELD OIL BURNER AND SYSTEM Filed se t. 27, 1939 s A m s VE 0F I CHARLES L. RAYF/ELO y 1944- c. L. RAYFIELD 2,347,842

OIL BURNER AND SYSTEM Filed Sept. 27, 1939 4 Sheets-Sheet 4 CHARLES L. RA YF/ELD Patented May 2, 1944 UNITED STATES PATENT OFFICE 2,347,842 011. BURNER AND SYSTEM Charles L. Hayfield, Chicago, Ill., assignor, by mesne assignments, to C. L. Rayfield Company, Chicago, 111., a corporation of Illinois Application September 27, 1939, Serial No. 296,718

Claims.

The present invention relates in general to improved means for the burning of oil for heating purposes and amongst other things is primarily concerned with improvements in such apparatus to the end that the less expensive, more viscous oils containing a greater number of heat units may be efficiently utilized for heating purposes.

Heretofore, oil burners for domestic heating, such as utilized for the heating of homes, apartment buildings, and the like, have been limited almost entirely to the use of the more highly refined and lighter oils which not only contain a less number of heat units, but are more expensive than the heavier and more viscous oils.

This limitation has resulted to a large extent from the apparent inability of manufacturers to heretofore build suitable apparatus for eflicient- 1y burning the heavier grades of oil, which could be assembled into a compact unit suitable for domestic installations. Where attempts were made to use the heavier oils, the installed apparatus usually entailed a complicated arrangement of piping between widely spaced parts of the apparatus and required considerable space for installation, all of which was objectionable and unsightly, especially in cases where the spaces containing the burner apparatus were to be utilized for game and play rooms, and the like.

More specifically, most oil burners are arranged to burn the so-called "Light oil No. 3, and it has heretofore been difiicult to provide satisfac tory apparatus for domestic heating which could be efficiently utilized to burn oils as heavy as the so-called No. 5 or "No. 6.

Having the foregoing in mind, the present invention contemplates as a primary object the provision of an improved oil burner and system which will efliciently and economically burn the heavier, more viscous oils.

A further object of the invention is to provide an improved oil burner and system embodying improved means for pre-heating the oil.

A further object of the invention is to provide an improved oil burner and system wherein air may be mixed with the oil under pressure to form a compressible mixture, before the mixture is atomized in the burner nozzle the apparatus being so arranged that th amount of air may be automatically controlled.

A still further object is to provide improved means in an oil burner and system ior'carbureting the oil by the induction of air thereinto before it reaches the burner nozzle It is likewise a further object of the herein described invention to provide an improved oil burner and system having novel pumping mechanism in which the oil may be pre-heated and mixed with air. I

A further object of the invention is to provide improved means in an oil burner and system for purging and flushing the oil nozzle, when the burner is shut down.

Another object of the invention is to provide an improved relief arrangement in the oil path of the burner, whereby oil may .be returned to a source of supply, whenever the burner nozzle becomes clogged.

A still further object of the herein described invention is to provide an improved oil burner in which metered quantities of oil are burned, and anysurplus pumped oil is automatically by passed back to a supply source.

Yet another object is to provide an improved oil burner and system for the burning of relatively heavy, viscous grades of oil, wherein the apparatus is equipped with improved control means for delaying starting of the burner until the oil has been pro-heated to a pretermined temperature.

Other objects and features of the invention will more fully appear from the following detailed description taken in connection with the accompanying drawings, which illustrate a single embodiment thereof, and in which:

Figure 1 is a plan view of oil burner apparatus embodying the features of the present invention;

Figure 2 is a longitudinal sectional view taken through the pumping part of the apparatus to show the details of the construction thereof, taken substantially on line 11-11 of Figure 1;

Figure 3 is a detailed view, partly in section, showing the valving arrangement of the pumping parts, taken substantially on line IIIIH of Figure 2-;

Figure 4 is a view looking into the housing for certain of the control equipment mounted on the burner, the cover of the housing being removed to show the control elements therein;

Figure 5 is an enlarged fragmentary sectional view showing the details of construction of the bleeder valve as utilized in the present invention, taken substantially on line VV of Figure 1;

Figure 6 is an enlarged fragmentary sectional 'view' of the carburetor construction utilized in the present invention, taken substantially on line VI-VI of Figure 1; and

Figure 7 is a schematic view of the oil burner and diagrammaticallydisclosing the piping systerns for oil and air, and also diagrammatically showing the control equipment and the electrical connections thereof.

As shown on the drawings:

From a consideration of the apparatus illustrated in Figure 1 of the drawings, it will be apparent that the oil burner and system of the present invention provides a compact unit assembly which may be readily applied to already installed or existing furnaces and boilers for heating purposes.

Burner apparatus in general As shown in Figure 1, the burner unit comprises in general an air blower A, ;fue l pumping mechanism B, and a main driving motor for actuating the blower and pumping mechanism.

The blower A is of conventional construction and comprises a main housing portion III for enclosing the blower blades orimpeller (not shown) which is connected to the driving shaft of the motor. This housing terminates at one end in a tubular extension II which forms an air inlet to the center of the housing Ill, the extension being circumferentially provided with a plurality of spaced air inlet openings 12. Control of the inlet openings .I2 isaccomplished by ,means of a slide plate I3 which is suitably supported on the outersurface of the extension .l,| forsliding movement thereover. This plate ,is provided with spaced openings I4 which are adapted to cooperate with the-openings I2 and adjust the effective air inlet openings so as to vary the amount of inlet air taken in by the blower.

The housing In is provided with a tubular extension |5 on its forward side, this extension defining an air nozzle for supplying the ,main combustion air to a fuel atomizing nozzle I6 mounted therein, as shown in Figure .7.

Returning again :to Figure .1, the pumpin mechanism :B'comprises arotarytype of pump I] for the pumping of oil only, and a secondpuinp l8 of the reciprocable type for the pumping of air and -oil for a purpose which will hereafter be more fully explained.

The rotary pump I1 is provided with a .suit- .able pipe connection fitting I9 at its inlet, and a suitable pipe connection fitting at itsoutlet.

The reciprocating pump i8, as more specifically shown in Figure 2, comprises ;a housing or casing 2| which serves at one side as a suppo t for the rotary pump housing structure 22 which encloses the rotary pumprotor23, this rotor bein mounted at one .end of a shaft .24 which also serves as the shaft for the pumpi elements of the reciprocating pump. Ifhe shaft 2, and the opposite wall of the housing .2I ,iromjthat to which the rotary pump housing is secured is provided with a suitable shaft bearing ;25 that is secured to the pump housingby means of ,suitable bolts '26.

The top wall of the housing=2| is providedwith an opening 21 for receivingthe vlowermost'end of acylinder defining block28 having-a peripheral flanged portion 29 for-receiving'holding down screws or bolts 3Bby means of which the block is secured to thethousing 2|.

The block 28 defines a pair of aligned cylinders 3| and 32 forreciprocably and operatively receiving the pistons '33 and 3.4. :Each of thepistons is connected by means of aconnecting link 35 to an eccentric on the shaft lL-the. eccentrics for'actuating the two pistons being' in 180.relaf tion. That is, when, one piston. is at. the" bottom of its stroke, the other piston will be at the top of its stroke.

It will be noted that the cylinder bores extend entirely through the cylinder block and are covered by a cap member 36 which defines the outlet manifold from the cylinder, a suitable gasket 31 preferably being provided at the joint between the cap and the uppermost end of the associated cylinder block.

As shown in Figure 3, a common inlet manifold 38 is suitably secured at one side of the cap member, this manifold having separate inlet connections 39 and 40 respectively communicating through ducts 4|with the interior of the cylinders, the ducts terminating in the undersurface of the cap 36 in each cylinder. The ducts 4| in eachcylinder are respectively controlled by a downwardly opening member or flap valve 42 which is anchored at one end as at 43 to the undersurface of the cap 38 with its free end overlying the entranceopenings of the ducts 4| into the cylinder.

As shown in Figure 2, the cap 35 has a longitudinally extending bore 44 having one end connected with a pipe connection fitting 45 and its other end connected with a pipe connection fitting 46. Intermediate the ends of the bore .44, the cap is provided with portions defining a valve socket 41 axially alignedand above each of the cylinders. This socket .is closed at its bottom, except for one or more outlet ports 48.

The upper end of each socket is arranged to be closed by a suitable plug 49 which may be screwed into the upperend of a socket against .a

suitabl gasket 50. This plug is recessed atits innermost end to receive one end of an expansion spring 5| which acts to bias a valve disk 52 into seated position over the outlet port from the associated cylinder.

In addition to the valving arrangement of ports as described above, the outlet valve for cylinder 32 is additionally provided with a small =by-pass port 53 which enables a small amount of :the fluid being pumped in cylinder 32 to be Joy-passed around its associated outlet valve disk The bottom wall of the housing 2| of the reciprocating pump structure is provided with a constructed .of a metal which preferably has a .high heat conducting characteristic, such as aluminum. The member 54 is constructed with a relatively thin shelled integrally formed capped portion 51 which extends upwardly through the opening 55 into the housing 2| and provides a downwardly opening recess 58 adapted to axially receive therein an electric heating unit 59. This heating-unit comprises a body portion of insulating material, such as an asbestos composition,

which is provided with a helically extending groove 60 in which a suitable heating element or resistance wire BI is disposed. The ends of the heating element are connected to suitable terminal studs-62 and 63 which are mounted in the body of the heating element and have threaded ends projecting from the recess or socket 58, these threaded ends being provided with suitable nuts '64 formaking connection to energy supplying conductors.

The. heating element is retained within the socket 58 by means of a retaining bolt 65 extending through the bot om .of the c pped Portion and a suitable bore in the body portion of the heater body, a nut 6511 being threaded onto the bolt 65 to cooperate with the head of the bolt 'for clamping the body portion of the heater against the bottom of the cupped portion.

With the construction just described, the heater may be easily removed from its position in the socket 58 simply by removing the nut 6511, Whereupon the heater may be taken out as a unit. Such an arrangement is particularly advantageous as it enables ready replacement of a heater should it become burned out, or in the event that it is desired to install heaters for operation on diiTerent voltages which may be available in different installations of the oil burner equipment.

As shown in Figure 1, the interior of the housing 2| is maintained open to atmosphere through a suitable breather 66.

The housing 2! of the reciprocating pumping mechanism comprises a reservoir for receiving oil which is supplied from the outlet connection of the rotary pump through a pipe connection 61, as shown in Figure 1, this pipe being provided with a number of turns which encircle the extension of the bore, these turns being in heat receiving relation with the burner nozzle and the fuel which is being atomized and burned. After encircling the extension I5, the pipe 61 is carried to the inlet of a float valve 68 having an outlet which is connected by a suitable pipe connection 69 to the interior of the housing 2 i The float valve 68 operates to maintain a predetermined supply of oil within the housing 2!. Normally this oil level is approximately at the shaft 24 so that the operation of the driving eccentrics for the links will act to churn and agitate the oil and enable its being more readily heated by the electric heater in the bottom of the pump housing 2| and by the heat generated by friction during operation of the pump parts.

By conducting the oil through pipe 61 through the turns around extension IS, the heating of the on is augmented. In fact, after the burner has started to operate, the electric heater is de-energized and the oil is sufficiently heated by its being passed around the extension [5.

The float valve 68 is also vented to atmosphere through a suitable breather 10.

On the opposite side of the blower casing I D from the extension l5, there is supported a housing 1! for the local control mechanism, the housing H having a removable cover 12.

Referring to Figure 4, the local control mechanism will now be described. Within the housing, there is provided a supporting bracket 13 which is secured to the rear wall of the housing by means of suitable screws 14. This bracket has a forwardly projecting L-shaped flange portion defining a long leg 15 and an uppermost shorter leg 16.

Associated with the uppermost leg 16 of the bracket is an elongate arm 11 which is flexibly connected to the leg 16 of the bracket by means of a leaf spring as shown at 18. This spring permits vertical swinging movement of the arm 11, this swinging movement being adjustable between abutment nuts 19 and 80 threaded on a stud bolt 8|, these nuts being adjustably positionable on either side of the arm 1'! to limit its swinging movement.

The arm 1'! is normally biased in a downward direction by a tensicned spring 82 having one end anchored to the leg 15 of the bracket, and its other end anchored to the arm 11.

The arm ll is moved upwardly in response to the action of the thermal responsive closed system. This system comprises a bellows 83 which is rigidly secured at one end to the leg 15 of the bracket and has its uppermost end provided with a head member 84 which bears against the underside of the arm 11 adjacent its connection to the leg 16 of'the bracket. Connecting the interior of the bellows 83 with a bulb 85 is a hollow conductor 86. The bulb, bellows, and conductor are filled with a thermal responsive medium, so that as the temperature to which the bulb 85 is subjected is varied, the bellows 83 will be caused to expand or contract depending upon whether the temperature is increased or decreased. Expansion of the bellows moves the arm Tl upwardly against the tension of spring 82, whereas contraction of the bellows permits the spring 82 to move the arm H in the opposite direction.

' The bulb 85 in the present instance is mounted within the pumping housing 2| previously described, and as shown in Figure 1. Thus, the bellows 83 and consequently the arm 11 will be moved up and down in response to variations in temperature of the oil within the housing 2!.

The movements of the arm T! are utilized for the opening and closing of switches. For this purpose a switch supporting bracket 81 is pivoted as at 88 for swinging movement, and this bracket is pivotally connected to one end of a link 89, the other end of this link being pivotally connected to the free end of arm 11.

One end of the bracket 81 carries a two-electrode type mercury switch 90 which is adapted in the down position of arm 71 to interconnect a pair of circuit conductors 9| and 92. The other end of the bracket 81 carries a three-electrode mercury type of switch 93 which is arranged in the closed position of switch 90 to interconnect conductors 94 and 96. However, when the arm 1! is raised, the bracket 81 will be rotated counter-clockwise and carry the switches to such position that the switch 90 will open its contact and switch 93 will disconnect the conductors 94 and 96 and connect conductor 94 with a conductor 91. The conductors connected with the switch may be brought out to suitable terminal blocks Within the housing I I.

There is also associated with the control mechanism, just described, an adjustable air intake valve 98 which is also supported upon the leg 15 of bracket 13. This valve is provided with a stem 99 having a threaded extension I00 at its uppermost end for receiving suitable nuts Ifll, the threaded extension extending through a suitable opening in the arm 17. By adjusting the nut H31, the amount of opening of the air valve may be determined in relation to the movement of arm 11. Moreover, regulation of the valve opening is adjustable by means of an adjusting screw 492. The air valve is connected to and controls the inlet of an air pipe I03.

Oil system Referring now'to Figure "I, the oil system will now be described. The oil is taken from a suitable source of supply such as a tank Hi4, which interior of the casing 2| of the reciprocating pump mechanism. -In other words, the float valve maintains a substantially constant oil level Within the casing 21 at all times.

'From the casing U the oil is drawn through a metering valve I66 of conventional construction by the action of the piston associated with cylinder 32 of the reciprocating pumping mechanism.

After the oil passes through the metering valve, it is carried through a pipe I01 to the intake of cylinder 32, and in so doing is conducted through a carburetor device I08.

This carburetor is constructed as specifically shown in Figure 6, and comprises an elongate body .portion I09 having a longitudinally extending bore H enlarged at its ends for receiving pipe connections. At its lowermost end, the bore I'Ill istapped by the connection of pipe I03 which extends laterally from the body. The body I09 is so positioned in relation to the float valve 68 that the oil level in the float valve will also maintain an oil level in the body I09 which is above the entrance of the air pipe I03. It will therefore be evident that as the oil flows through the body I09 from the bottom towards the top thereof, as shown in Figure 6, air will bedrawn into the oil stream. The air and oil will thus become mixed and an attenuated mixture of air and oil formed. It will thus be apparent that the piston acting in cylinder 32 will pump an attenuated mixture of air and oil and discharge it into the outlet manifold of the reciprocating pump mechanism.

The rotary pump I1 is arranged to pump a greater amount of oil than will be required to be delivered through the metering valve. The surplus oil, particularly when the float valve is closed, will be delivered through .a return pipe III back to the supply source in tank I04. The pipe III contains a relief valve H2, which is set to open at approximately one to two pounds oil pressure acting in the direction of flow of oil in its return to the supply tank.

The attenuated mixture of air and oil, the oil having been carbureted in the carburetor I08 and further mixed under pressure in the cylinder 32 and discharged into the outlet manifold of the reciprocating pump mechanism, will build .up a pressure in a pipe line II3 which connects the outlet manifold through a ball relief valve IM with the pipe III just ahead of relief valve H2. The relief valve H4 is of the ball type and is set to open at substantially 90 pounds pressure.

Connected 'ahead of the relief valve H4 is a pipe I I5 which connects through a bleeder valve I I B toa closed tank or container I H.

The construction of this bleeder valve is disclosed in detail in Figure 5. As will be noted, the bleeder valve comprises an elongate casing IIB having a longitudinally extending bore I I9 which communicates at its innermost end with an expanded bore portion I20 to form a valve seat. The valve mechanism is housed within the portion I20 and comprises a valve member I2! having a rounded nose portion adapted to seat upon the innermost end of the bore N9, the valve member being resiliently actuated to seated position by means of an expansion spring I22.

The rounded seating end of the valve member is provided with a small surface'groove I 23 which permits bleeding of air from the pipe II3 into the tank In. During normal operation of the .bu1ner,,the bleedingof airinto the tankl I'l will build up an air pressure in the tank of substantially the same as the operating pressure at the nozzle. This tank in the line obviates surges and-the air therein is used for purging and cleaning as described hereinafter. During normal operation, the valve member I2I will remain in closed position as shown in Figure 5.

Air system As previously described, air is taken in through the pipe I03 by the carburetor I08 and mixed with the pumped oil to form an attenuated mixture of air and oil. The piston of the reciprocating pump mechanism which is associated with cylinder BI is utilized for the pumping of air only, the inlet to this cylinder being supplied through an air pipe I24 which is carried to and has its inlet end disposed within the control housing II, this housing protecting the air inlet against the entrance of dirt and other objectionable materials. Operation of the piston in cylinder 3| compresses the air and discharges it into the manifold of the reciprocating pumping mechanism where it combines and is further mixed with the attenuated mixture discharged from pumping cylinder 32. The manifold from the reciprocating pumping mechanism is connected to a pipe I25 which conducts the air and oil as they are mixed to the atomizing nozzle I6, where the mixture is discharged at pressures ranging from substantially 40 to pounds. The atomized fuel, when ignited, is burned in the combustion supporting air delivered from the blower through the tubular extension I5.

A governing effect is provided by mid-point positioning of the valve 98 which is determined by the temperature of the compressor as reflected on the bulb 85. Thus Where there is a high boiler room temperature the compressor chamber temperature will be higher, causing the bellows 83 to expand and push its head member 84 against the bar I8, thus opening the valve to admit additional air and maintain the desired even flame.

Control mechanism control devices are utilized in order that the burner may be automatically started and stopped according to the heating requirements.

As further shown in Figure 7, the control mechanism in the casin H may be coordinated with additional control relays, etc., which may be variously constructed to accomplish the desired control of the burner. In the present instance, I have shown schematically a repulsion type relay as generally indicated at I 20. This relay comprises a magnetic yoke I21 with which there is associated a fixedly mounted primary coil I28 and a movably mounted secondary coil I29 which is supported on a pivotally mounted arm I30. With this type of relay, when the primary coil I28 is energized, the secondary coil is energized due to the transformer effect between the coils. At the same time, magnetic repulsion between the primary and secondary coils causes the secondary coil to swing away from the primary coil. This action brings the arm 30 to a constitute a two-electrode mercury switch I33 carried on a swingable bracket and normally biased to open position. The bracket is arranged to be latched by a suitable latch member I34 of bi-metallic material. The safety switch is moved to normally closed position in which it is latched by the bi-metallic member I34, but upon the temperature of the bi-metallic metal of the latch reaching a predetermined amount, the latch member will release the safety switch and permit it to be biased to open position. The temperature of the bi-metallic latch member is controlled by means of a heating coil I35.

As also included in the control diagrammatically represented herein, a flue thermostat relay I36 which is responsive to flue temperatures, when cold, is arranged to interconnect a pair of contacts I31, but, when heated, to open the contacts I31 and close another pair of contacts I33.

As in most control systems for oil burners, the present system includes a room thermostat as generally indicated at I39 having a pair of normally opened contacts I49, which are adapted to close upon a rise of room temperature.

Operation Let it be assumed that the oil burner has been standing idle and that the oil in the casing 2| i cold. The control devices will then be in their normal positions as shown in Figure 7.

Under such conditions, it will be noted that th primary coil of the repulsion relay will be connected to a source of current supply I4I through the following circuit: from one side of the current supply through the closed contacts of safety switch I32, conductor I42 to one side of primary coil I28, conductor I43, and thence through conductor I44 to the other side of the main current supply. Thus the primary coil is across the line and will be energized. However, the primary coil will not repulse the secondary coil I29, since it is open-circuited as the result of the contacts I 46 of the room thermostat in the secondary coil circuit being in open position.

Let it now be assumed that the thermostat calls for heat, and that this thermostat closes its contacts I40 due to fall of room temperature. Closing of the thermostat contacts I46 operates to close the secondary coil circuit as follows: from one terminal of coil I29 through conductor I45, conductor I46, conductor 92, the contacts of switch 90, conductor 9|, conductor I41, conductor I48, contacts I49, conductor I49, and thence back to the other terminal of coil I29. The secondary coil circuit thus being completed, current will flow in the secondary coil with the result that the secondary coil will be repulsed from the primary coil, and the relay will operate to close contacts I3I.

Closing of contacts I3I energizes the heater 59 in the bottom of casing 2| through the following circuit: from one side of the current supply I M, through the contacts of the safety switch I 32, conductor I42, contacts I3I, conductor I59 to one side of the heating element of the heater 59, and the other side of this heating element through conductor 96, the closed'contact switch 93, and thence through conductor 94 to the other side of the current supply.

The heater 59 continues to pre-heat the oil in the casing 2|. This heating of the oil continues until it reaches substantially a temperature of 165 F. As the temperature of the oil continues to increase, the closed thermal responsive system expands the bellows 83 and causes switches 99 and 93 to move to a position wherein they tilt downwardly to the right instead of downwardly to the left. In this changed position, the contactsof switch are opened, and conductor 94 is disconnected relative to conductor 96, whereupon the circuit through the heater 59 is opened. At the same time, conductor 94 is connected with conductor 91 and the motor C of the oil burner becomes energized through th following circuit: from one side of. the electric supply circuit, through the contacts of safety switch I32, conductor I42, contacts I3I, thence through conductor I5I to one terminal of the motor, from the other terminal of the motor through conductor 91, th right hand contacts of switch 93, and thence through conductor 94 back to the other side of the main current supply.

The motor now being energized starts to operate the blower and pumping mechanisms. The action of cylinder 32 draws heated oil through the metering valve, and the carburetor I68 where air is combined with the oil as previously described, it being understood that the valve 98 is so regulated that when the switches 99 and 93 are actuated as just described, the valve 98 will also be opened to admit air to the carburetor.

At the same time, cylinder 3| starts drawing in air which is compressed and combined with the attenuated mixture discharged from cylinder 32. The mixed oil and air is then conducted through pipe I 25 to the nozzle I6, where oil is atomized into a combustion supporting atmosphere produced by the air issuing from the blower A through the extension I 5.

Simultaneously with the starting of the motor, energization of the motor completes a circuit through the primary of an ignition transformer as follows: from one side'of the main current supply I4I, through the contacts of the safety switch, conductor I42, contacts I 3!, conductor I 5I, conductor I 53, contacts I31, conductor I54 to one terminal of the primary of the ignition transformer, from the other primary terminal through conductor I35, and thence through conductor I44 back to the other side of the supply circuit. The ignition transformer thus being energized, an ignition spark is emitted adjacent the nozzle I6 between a pair of electrodes I56 which are respectively connected by conductors I51 and I58 to the respective ends of the secondary winding of the ignition transformer.

Assuming now that the atomized fuel'issuing from the nozzle I6 is ignited, the hot gases passing out the flue of the furnace will actuate the flue thermostat to such position that it will open its contacts I 31 and disconnect the ignition transformer. At the same time it will close its contacts I38 which operate to short circuit the heater I35 of the safety switch through the following circuit: from one terminal of the heater, through conductor I46, conductor I59, contacts I38, conductor I69, and thence through conductor I41 to the other terminal of the heater coil I35.

The burner will now continue to operate until suflicient heat is furnished to the room containing the room thermostat. When-the temperature has reached the amount for which the room thermostat is set, it will open its contacts I49 and thereupon opeh-cirouit the secondary coil I29 of the repulsion relay. The secondary coil then moves towards the primary coil and opens the contacts I3I, whereupon the motorcircuit is deenergizedand the burner discontinues its operation'. j

In the event that the ignition spark doesnot ignite the atomized fuel issuing from the nozzle It, then the: flue thermostat continues to retain contacts I31 closed. Since the contacts of switch 90 are at this time opened, the heating coil I35 will be in the room thermostat circuit of the sec.- ondary coil I251; The heating coil I35 is thus energized from the secondary coil I29, and due to its heating effect upon the thermostatic strip of himetal l34, this latch will be deflected after a predetermined interval of time to a position where.- in it will release the safety switch 132, so that the mercury switch I35 will be moved under the action of its biasing spring. to a position wherein it will open its contacts and shut down" the motor driving the burner. The burner will then be left out until such time as the safety switch is manually reset.

When the burner shuts down, the air which has become stored in the tank Ill will open the bleeder valve H6 and be discharged through the pipe I25 and nozzle l5, thus purging and cleaning out the system.

If, for any reason during the operation of the oil burner, the nozzle 16 should become clogged so as to prevent the atomization of the attenuated fluid thereby, a pressure will build up behind the nozzle. In my improved system, this pressure is relieved by the opening of relief valve H4 which permits the passage of fluid from the outlet manifold of the reciprocating pump mechanism through the by-pass valve HZ back to the supply tank.

If the burner has been operating continuously or atsufiiciently close intervals to have kept the oil in the casing 2| of the reciprocating pumping mechanism at a sufliciently high temperature, the burner will start upimmediately upon a call for heat by the room thermostat and there will not be instituted the time delay previously described for energizing the heater 59 for preheating the oil.

From the foregoing description, it will be apparent that the present invention provides an improved oil burner and system which will efficiently and economically burn the heavier and more viscous oil;. whichincludes improved means for preheating the oil; which is so arranged that air may be mixedwith the oil under pressure toform a combustible mixture, before the mixture is atomized in. the burner nozzle, the amount of air being automatically controlled; which embodies improved means for carbureting the, oil

by theinjection of air before the oil reaches theburner nozzle; which includes novel pumping mechanism in which the oil may be pro-heated and mixed with air under pressure; which is provided with improved means for purging and flushing the oil nozzle, when the burner is shut down;

which has an improved relief arrangement in the oil path, whereby oil may be returned to a source of supply whenever the burner nozzle becomes clogged; a burner arranged to utilize metered quantitiesof oil and by-pass surplus pumped oil back to a supply source; and which utilizes; improved control means for delaying starting of the burner, when cold, until the oil has been preheated to a predetermined temperature.

Now, it is, of course, to be understood that although I have described in detail the preferred embodiment of my invention, the invention is not to-be thus limitedvbut only insofar as defined by the scope and spirit of the appended claims.

A I claim as myinvention:

In an oil burner construction in which mixed airand oil are supplied to" a. fuel nozzle,v an air aeezsaa.

supply, an oil supply, pumping means for pump ing air and oil from said supplies and delivering mixed air and. oil to said nozzle, means for preheating the oil, and means responsive to the temperature of the preheated oil for controlling the amount of air supplied to the pumping means.

2:. In an oil burner construction of the type in which mixedair and oil are supplied to a fuel nozzle for injection into an entraining, combustion supporting atmosphere, an air supply, an oil supply, pumping means for pumping air and oil from said supplies and delivering mixed air and oil to said nozzle, means for heating the oil, and control means responsive to the temperature of said heated oil for starting the entrainment of said mixed air and oil into-said combustion supporting atmosphere; said control means including a valve in said air supply.

3. An oil burner comprising a fuel atomizing nozzle, an oil pump, means for heating the pumped oil, a carburetor for mixing air with the heated oil to form an attenuated mixture, pumping means for compressing the attenuated mixture, and means for adding additional compressed air to the attenuated mixture and delivering it to said nozzle where it is atomized, and means for delivering a main air supply to the atomized mixture.

4. Oil burning apparatus comprising a nozzle,

pumping means comprising, a pump device for pumping oi-l only at one stage, another pump device for supplying air under pressure at another stage, and an additional pumping device for pumping combined air and oil at a third stage, means for conducting the combined air and oilto said nozzle, and means for pro-heating. the oil prior to its being combined with said air.

5. Oil burning apparatus comprising a fuel nozzle, a pumpmechanism having separate elements for respectively pumping oil, air, andoombined oil and, air, means for heating the oil before it is combined with the air, means for conducting the combined oil and air to said nozzle,- and means for supplying combustion supporting air to said nozzle.

6. In an oil burner in which oil and air are combined to form a combustible mixture; a fuel delivery nozzle, pumping means for supplying the combustible mixture: to said, nozzle, means for pre-heating the oil, temperature responsive means for energizin the oil pro-heating means, a thermally actuated mechanism responsive to the temperature of the" pro-heated oil for simultaneously starting the burner and de-energizing' the pre-heating means, and means surrounding and in heat receiving relation to said nozzle for continuing the heating of said oil during normal burner operation.

7. In oil burning apparatus, a nozzle, a casing defining a reservoir for oil, pumping elements in. said reservoir casing, certain of said elements being arranged to pump air and others of the elements being arranged to pump oil. from said reservoir, and means for pre-heating the oil and pumping-- elements insaid; casing, a; manifold connecting the outlets of said pumping elementsfor mixing oiland air therein,. and means con-' meeting said nozzle; with said manifold;

8. In an oil burner, a pump having. separate chambers, a combination oil and air inlet arrangernentto one or said chambers, air inlet means to; the Second of said chambers, each of; said chambers having an outlet,. a manifold enclosing; said outlets within which additional air. from the Second. chamber'is mixed with: the oil and air mixture from the first chamber, a valve governing the admission of air into said combination inlet arrangement, and means associated with said valve governing the air passing therethrough in accordance with the temperature of the pump.

9. In an oil burner in which liquid fuel and air are combined to form a combustible mixture, a liquid fuel supply, a first pumping means for pumping fuel from said supply, means for preheating said pumped fuel, a housing forming a reservoir to receive said pre-heated fuel, heating means arranged to further heat the preheated fuel in said reservoir, a second pumping means to remove heated fuel from said reservoir, a carburetor for mixing air with the heated fuel from said reservoir to form an attenuated mixture which is received and compressed by said second pumping means, thermal means responsive to the temperature of fuel in said reservoir to control the operation of said second pumping means, additional means in said second pumping means to add additional compressed air to the attenuated mixture to form a combustible mixture, a fuel atomizing nozzle for receiving said combustible mixture, and means to deliver a main air supply to the combustible mixture atomized by said nozzle.

10. In an oil burner having a blower provided with electrically energized driving means and in which oil and air are combined to form a com- 10 bustible mixture, a fuel delivery nozzle, pumping means for delivering the combustible mixture to said nozzle, electrically energized means to preheat the oil handled by said pumping means, temperature responsive means for energizing the 15 oil pre-heating means, a thermally actuated mechanism responsive to the temperature of the pre-heated oil and including bellows means, electric supply circuits, and switches actuated by said bellows means for opening and closing said 20 circuits for simultaneously starting the blower and de-energizing the pre-heating means.

CHARLES L. RAYFIELD.

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