US2022879A - Liquid fuel burner - Google Patents

Description

Dec. 3, 1935. J. CARLBERG I LIQUID FUEL BURNER File'd March 1, 1935 3 Sheets-Sheet l 5 Sheets-Sheet '2 Dec. 3, 1935. J. CARLBERG LIQUID FUEL BURNER Filed March 1, 1935 w w a fl ew Dec. 3, 1935. J. CARLBERG LIQUID FUEL BURNER 5 Shets-Sheet 3 Filed March 1, 1933 Patented Dec. 3, 1935 UNITED STATES PATENT. OFFICE LIQUID FUEL BURNER John Cariberg, Hartford,- Conn, assignor to The Silent Glow Oil Burner Corporation, Hartford, Conn, a corporation of Connecticut Application March 1, 1933, Serial No. 659,134 3 Claims. (01. 158-28) This invention relates to liquid fuel burners, be-

ing more particularly concerned with the convalve and the companion auxiliary high and low fire valve;

Fig: 3 is a cross-sectional plan of a portion of the auxiliary valve and metering valves as shown in Fig. 2;

Fig. 4 shows in perspective the plunger for the auxiliary valve;

- Fig. 5 is similar to Fig. 3 but showing a modified form of metering valve;

Fig. 6 is a simplified diagrammatic view of the electrical connections; and

Fig. 7 is a more elaborate diagrammatic view.

Referring to the drawings and to the embodiment of the invention selected for illustrative purposes, the apparatus comprises a conventional type of rotary centrifugal burner having a rotary cup i i to which liquid fuel (herein for descriptive purposes referred to as oil) is fed and by which it is delivered in more or less atomized form to the combustion chamber of a furnace (not shown).

The cup is-fixedly secured by means of a spider member l3 to a driving shaft I5 driven by the electric motor l'l, oil being entered into the rear openend of the cup through the delivery pipe I! and discharged from the open and somewhat flared mouth of the cup. At or adjacent the mouth of the cup there is maintained a gas igni tion flame 2! which, if desired, may be automatically expanded and contracted with the starting and stopping of the burner. The mouth of the cup projects slightly beyond'the mouth of a surrounding air distributing nozzle 23 spaced from the cup and providing an annular air passage communicating with the discharge end of a fan, the housing forwhich is shown at 25, and

which is also driven by the motor l1. Oil is supplied from a main tank through a pipe connection 21 to a pump 29, also driven by the motor 11-. The pump delivers the oil through the discharge pipe 3| and pipe connection 33 to a filter 34 and thence through the pipe connection 35 tomain and auxiliary control valves I 31 and 39, from the latter of which it passes through the pipe connection 4| and the delivery 5 pipe I9 to the cup II. I

The pump discharge 31 has connected to it' a relief valve 43 to return excess oil to the tank and the pipe connection 35 is provided with a pressure gauge 45. The control panel 41 carrying relay switches and other electrical control devices for the automatic operation of the burner is mounted on the frame of the apparatus ad- Jacent the casing of the motor i1.

In the operation of an oil burner of this type, it is common practice when the motor is started, as by the functioning of a room thermostat, to defer the delivery of oil to the cup for a short interval to permit the cup to attain full speed and 1 then to open the main oil valve, whereupon a full supply of oil is delivered to the cup. This method of starting is apt to be and often is accompanied by some difficulty in effecting a quick ignition of the large body of oil delivered to the cup. Thesudden introduction of a relatively large supply 95 of oil to the high speed rotary cup momentarily checks the smooth and even delivery of the oil and interferes with the proper atomization, and a substantial interval of time elapses before equilibrium is established and the cup begins to function in effecting the required degree of atomization. During this interval a substantial amount of unignited oil has been delivered to the combustion chamber, so that a backfire or puff of greater or less intensity frequently accompanics this method of starting the burner, especially if started cold.

I have found that if, when the cup is first started into operation by the starting up of the motor, a relatively small supply of oil is delivered to the cup, the required atomizing action may be immediately established and maintained without the disturbance referred to, an even, uniform delivery of the oil is at once effected-and one having a superabundance of air, possessing higher explosive properties than one in which there is an abnormal proportion of oil. This condition of noiseless ignition is further insured in the present invention by providing for the delivery from the cup to the combustion chamber of the oil, although at the low rate of supply, substantially at the time the motor and fan first start into operation and before the latter has had opportunity to buildup its normal supply of air, so that the most favorable conditions for a soft start as well as for a quick start are created at the outset and in the initial stages of fan and motor acceleration when the air supply, while rapidly increasing, is very restricted in amount and abnormally low as compared with the amount of oil supply.

The construction of the main and auxiliary valves (shown in detail in Figs. 2, 3, and 4) and the electrical control of said valves (Fig. 6) herein provide for the initial delivery of oil to the cup when first started at a relatively low and ad justable rate, providing a low starting fire, this being followed after the lapse of a short interval by the delivery of oil to the cup at a relatively high and also adjustable rate, providing a high fire for normal operation of the burner.

Referring to Figs. 2, 3, and i, the main control valve comprises a casing having the adm ssion port 49 communicating with the supply pipe connection as and opening into a delivery port til. When the burner is out of operation, the port 5! is closed by the tapered head 53; of a valve stem 55 which head rests in a seat provided at the mouth. of the port 5i. The stem 55 fits loosely in the axial bore of the solenoid plunger 5! projecting somewhat above the top of the latter and terminating in an enlargement 5s. The plunger is slidably mounted in the valve casing and in a tubular, non-magnetic cap dd projecting thereabove and is subject to the magnetic fielder a surrounding magnet winding ti covered by the protecting cap 83. When the winding is energized on the starting of the burner the plunger is lifted, striking the enlargement Ell, raising thevalve 53 and opening wide the delivery port 5! to the. oil delivered by the pump. When the winding is deenergized, the plunger drops by gravity, engaging the tapered valve head and forcing it to its seat to close the delivery port.

The delivery port 5! has the pipe connection.

65 to the casing for the auxiliary valve 39, which connection communicates with the admission port 61, the latter opening into a main delivery port 68. When the burner is out of operation the port 68' is closed by the tapered head ll of the valve stem. l8, similar to the stem 55, and adapted to be actuated by a plunger 15 slidable in the casing 39 and the tubular cap 16. The plunger is controlled by the magnet winding 'l'l having the protecting cap 79, so that the valve operates in a manner similar to the described operation of the main control valve.

The delivery port 69 communicates with the delivery chamber 88 near the bottom of the valve casing 8Q, the delivery chamber in turn communicating with the pipe connection 4i leading to the cup.

When the magnet winding H is energized, the valve H is lifted, rendering available the full area of its delivery port forthe supply of oil to the burner. When the winding is deenergized, the valve M is caused by the plunger 75 to close its delivery port, but means are provided in the closed position of the valve for establishing aoaaavo through a by-pass to the delivery chamber 8| a relatively small and regulatable amount of oil. To this end the lower part of the plunger overlying the port 81 in the deenergized condition of the magnet winding has a square or other non- 5 circular cross-sectional shape, and there is provided also confronting the squared lower end of the plunger 9, second or by-pass port 83 which also communicates with the delivery chamber 8i through the connecting port 85. Even' with the auxiliary valve H closed, therefore, a quantity of oil is free to flow from the port 81 under and around the plunger body into the port 83 and to the cup at a rate dependent upon the crosssectional area of the passages provided. This 15 auxiliary or by-pass supply is designed to provide the initial or low fire supply heretofore referred The ports 61, 83, and 85, for better understanding, are shown in Fig. 2 as if located in the same in vertical plane instead of as they are shown iii Figs. 3 and 5 and as they actually appear in plan.

Means are herein provided for adjusting the by-pass supply to suit the particular conditions 25 pertaining in any given burner and also to adjust the high fire or normal supply and to adjust each with relation to the other. For this purpose there is provided between the ports 83 and 85 a metering valve comprising a pin 81 fitting more or less 36? loosely in a bore transverse the port 83 and having a projecting head, in the end of which there is formed a longitudinal V-shaped groove increasing in depth toward the end of the head and merging into a circular cross-section at a point 85 removed from its tip. The pin is carried by a member threaded into the side of the valve casing and having a projecting head 89 at the front of the casing (Fig. 1) by which its position may be adjusted. Between the head and the threaded 40 portion the pin has an enlarged tapered shoulder 88 (Fig. 3) adapted to be brought to a positive seat to entirely close the port. By the adjustment referred to, the end of the metering pin may be projected more or less between the ports 83 and 45 85, thereby providing for an accurate, graduated control of the available port cross-sectional area and adjusting the rate of low fire supply from what is permitted by the full cross-sectional area of the ports 85 and 83 to a point where, if desired, the supply is completely out ofi by the closure of said ports.

To regulate the main oil supply a similar metering valve 9| having the external adjusting head 83 is provided in such a position that it may be projected across the port 81 and adjust the opening of that port to any extent desired.

Accordingly, when the valve H is closed a low fire supply of oil may pass the valve at a rate fixed by the metering valve 81, and when the valve is 60 opened a high fire supply may pass, comprising not only the low fire supply butadditlonally the main supply passing through the delivery port 69, the high fire supply being limited by the adjustment of the metering valve 8|.

For installations requiring a relatively large consumption of oil, metering valves, such as are shown in Fig. 5, may be employed in which a. tapered valve head 92 replaces the grooved pin, the head being cooperatively related to a correspondingly tapered seat to open or close the port.

The properly timed control of the valves is efiected by electrical connections, which in simplified form may be represented in Fig. 6. Current is suppliedto the apparatus from the main 75 Ill conductors 93, 95 under the control of the usual .form of room thermostat 91. When the thermostat acts to close the circuit, the motor, which is connected in shunt thereto, is energized, the cup is started rotating, and simultaneously there is also energized the winding SI for the main valve 37, thereby permitting a supply of oil to be simultaneously delivered through the by-pass in the auxiliary valve 39 at a relatively low rate determined by the adjustment of the meteringvalve 81 The winding ll for actuating the auxiliary valve 39 is in a shimt circuit 99 which at the time referred toremains broken by the switch Ill I, not being closed until the latter is actuated. The switch is herein shown as representative of any suitable, time-actuated, circuit-changing device, and comprises a sealed glass tube containing a small body of mercury and pivotally mounted so that it may betipped to an inclined position in which the mercury electrically connects two terminals, the latter sealed in the tube at one end thereof but externally connected to the two sides of the circuit 99. When tilted to a reverse inchnation (as shown in the drawings), the mercury flows to the opposite end of the tube, thereby holding the circuit open.

To actuate the switch, the latter .is' adapted to be'moved to one position or the other by the bending movement of a bi-metallic thermostatic strip I03, the lower end of which is fixed and the upper end of which is in engagement with the switch. Surrounding the strip there is a heating coil I05 which is also in shunt across the main circuit 93, 95. When the main circuit is opened and the burner out of operation, the switch It! is in. the open position shown in Fig. 5. When the thermostat acts to close the circuit for starting the cup into rotation with the low fire supply as already described, current passes through the heating coil we, gradually raising the temperature of the iii-metallic strip I03, and finally, after I the lapse of an interval, causing the latter to flex burner to which it is applied and may be prede-a termined by the design or selection of the winding I05 and the thermostatic strip. By way merely of a numerical example such interval may be thirty seconds. y

In the practical installation of the high and low fire control where safety devices are employed'designed to stop the delivery of melon failure to establish normal conditions of combustion after the lapse of a safe interval of time following the starting of the motor, or on failure to maintain such condition for a'safe interval, it becomes desirable to coordinate the timing of the low and high fire control with such safety devices, so that the cup may function through the desired successive stages and the safety devices willact to stop the motor only after the lapse of a-further and substantial interval of time following the increase in the rate of fuel .supply-result-= ing from the opening of the auxiliary valve. An arrangement designed to accomplish this is shown conventionliiy and diagrammatically in Fig. 7.

Referring to Fig. 7-, there is provided a circuit closing device I01, herein termed, merely for purposes of designation, the main switch, this being of the tubular mercury type already described.

This switch is normally open (as shown in Fig. 7) 5 conductors I23 and I25 and to main through 15 conductors I21 and I29. It also simultaneously opens the main oil valve 31', the magnet coil SI for which is connected through conductor Hi to conductor; I25 and through conductor I38 to conductor I29.

so I This starts the rotation of the cup and the delivery of oil at the low fire rate. The heating coil I05 for the timing switch I BI is simultaneously out into circuit, one terminal being connected to the main 95 through conductors 35 and I29 and 35 the opposite terminal to main 93 through conductors I31 and Ill, switch-H5, conductor lit,- magnet I09 and conductor II I.

Afterthe lapse of a selected time interval, thirty seconds for example, the "timing switch 9 thirty seconds for example, the timing switch IOI net winding ill for the low and high fire valve 39 and opening the latter to provide a full rate of oil. supply to the fuel distributing device or cup. One terminal of the winding 11 is connected to the 35 main 83 through conductor 13! and the path already described for winding 5!, and the opposite terminal on closure of the timing switch is con, nected to main 95 through conductors I39 and llLswitch ifli, and conductors I43 and I29.

The main 93 passes through a safety switch I45 which is normally held closed by a detent comprising a bimetallic thermostatic strip I41, the latter within the influence ofthe heating coil I25. When operation of the apparatus is initi- 45 atedby the action of the thermostat, current passes through the heating coil, and it continued for a sufficient interval the strip is caused to flex,

the safety switch is tripped, the circuit of the the delivery of oil is stopped until the safety switch is reset by hand.

If normal conditions of combustion, however,

' are established within the interval required form;

the tripping action of the thermostatic detcnt,

the heating coil III is automatically cut out of circuit together with the heating coil I05 for the gtimingswitch II, and circuits excluding said heating coils are simultaneously established for so energizing the coil 11 of the valve 38 and for holding'the main switch I0! closed. For this purpose there is provided a combustion responsive device I 49 exposed to the products of combtlstion in thecombustion chamber or the ilue c5 of the furnace and receiving heat therefrom. This may be of the well-known thermostat type and adapted, when such a temperature is reached as indicates suitable or normal conditions of combustion. provided it is attained before the safety 70 switch opens, to close normally open contacts at the responsive device and complete a circuit through magnet I 5 i the latter connected to open the ci'ih'ihustion switch H5 and close its companioii switch 15:. 15

One terminal of the magnet I5! is connected to main 95 through the conductor E55, the comhustion responsive device E45, and conductors ifi'l, 559, and H9, and the opposite terminal is connected to the main 93 through-conductor Mil. The opening of the switch I 95 cuts out of circuit the heating coils M5 and IN. The simultaneous closing of the switch i553 energizes a holding magnet ass which retains the main switch llll closed, and also connects one terminal of magnet lll di rectly to the main to. The holding magnet .53 has one terminal connected to main 93 through conductor liil when switch l53 is closed, the opposite terminal being connected to main 95 through conductors 365 and iii, switch H53, and conductors I59 and H9. At the same time the conductor M9 for magnet ll is also connected directly to main 95 by the conductor i6] and switch I53.

The timed action of the heating coil it! may be predetermined by design of the coil and the cooperating thermostat detent, and should be such that the time interval required for its action when this coil is subjected to a continuous current flow is in excess of the time interval required for the actuation of the timing switch ilJl, so that the cup may receive oil at the low rate of delivery for a short interval, such, for example, as halt a minute, and may thereafter receive oil for a further substantial interval, such, for example, as one minute, before the tripping device can act. This provides for the necessary time relation between control devices so that, after the opportunity is had for ignition with the low fire supply, there is a substantial interval in which combustion may develop under the high fire supply and the functioning temperature of the combustion responsive device he certainly reached, except in cases of abnormal function failure of the burner.

While I have herein shown and described for the purposes of illustration one specific embodiment of the invention, it is to be understood that this is submitted for illustrative purposes only and that extensive deviations and changes in the character and relation of the elements employed and other applications of the means herein disclosed may be made, all without departing from the spirit of the invention.

I claim:

1. In combination with a liquid fuel burner having a motor driven rotary distributing device and a fuel feeding means therefor, a control circuit including said motor, a main thermal control switch, a first magnetic valve which is opened when energized to feed ,fuel at a relatively low rate, a second magnetic valve which is opened when energized to feed fuel at a relatively high rate, a flrstthermal time switch having a heater and operative when energized for a predetermined time to terminate burner operation, a second thermal time switch having a heater and operative when energized for a time period less than said predetermined time to energize said second valve, and a combustion responsive switching mechanism controlling burner operation and cooperating with the main control switch upon clo- .5 sure of the latter in response to a demand for heat to energize said motor, said first magnetic valve, and said thermal time switches, and in response to the establishment of combustion within said predetermined time to deenergize said 10 thermal time switches, to maintain the motor energized, and to maintain or establish energization of said second valve.

2. In combination with a liquid fuel burner having a motor driven rotary distributing device and a fuel feeding means therefor with means to effect delivery of fuel to said distributing device at a relatively low rate, a control circuit including said motor, a main control switch, a valve with means to open the same to insure delivery oi fuel at a relatively high rate, a first thermal time controlled switch operative when energized for a predetermined time to terminate burner operation, a second time controlled switch operative when energized for a time period less than said predetermined time to open said valve, and a combustion responsive switching mechanism controlling burner operation and cooperating with the main control switch upon closure of the latter in response to a demand for heat to energize said motor and said time controlled switches and in response to the establishment of combustion within said predetermined time to deenergize said time controlled switches to maintain the motor energized and said valve open.

3. In combination with a liquid fuel burner having a motor driven rotary distributing device and fuel feeding means with means to effect delivery of fuel to said distributing device at a relatively low rate, a control circuit including said motor, a main control switch, controlling means for insuring delivery of fuel at a relatively high rate, a first time controlled switch with timing means operative when energized for a predetermined time to terminate burner oporation, a second time controlled switch with timing means operative when energized for a time period less than said predetermined time to actuate said high delivery control means, and a combustion responsive switching mechanism 5 controlling burner operation and cooperating with

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