US2067446A - Burner control - Google Patents

Description

Jan. 12, 1937. J GOOD BURNER CONTROL Filed Feb. 20, .1955

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AT NEYS.

Jan. 12, 1937'. J. GOOD 2,067,446

. BURNER CONTROL Filed Febv 20, 1955 5 Sheets-Sheet 2 ii FUEL E TANK.

INVENTOR.

A T RNEYS.

Jan. 12, 1937.

J. GOOD 7 BURNER CONTROL Filed Feb. 20, 1933 s Sheets-Sheet a IN V EN TOR.

ATT

Patented Jan. 12, 1937 UNITED STATES PATENT OFFICE 5 Claims.

The invention relates to burners and has for its object the provision of a burnersuited to domestic heating, using oil as fuel, although not limited thereto, and characterized by its simplicity and its safety under all conditions of operation. More particularly the invention contemplates the automatic control of the air supply whereby the fuel and air mixture will be ap-, propriate to combustion requirements during nor-' mal burning but will be rendered unduly lean, and hence non-explosive, whenever a dangerous condition would otherwise be present.

The invention consists in the means for accomplishing this purpose and in the general assembly and organization of parts all as herein described, and its principles are exemplified i the accompanying drawings, in which Fig. 1 is a part sectional view of an oil burner embodying those principles,

Fig. 2 a large scale elevation of part of the controlling mechanism.

Fig. 3 a smaller'scale elevation of the burner and an appropriate controlling system,

Fig. .4 a detail of an addition to the control system of Fig. 3, and

Figs. 5 and 6 diagrammatic views of two modi fied forms of the invention.

In accordance with the well understood operaablower 2, for supplying combustion air and also drives an oil pump 3 having its intake and discharge connected bypipes 4 and 5, respectively,

with a source of supply; such as the fuel tank shownin Fig.3, and with the burner. A return pipe 6 serves to maintain a constant oil delivery pressure under the control of a spring loaded relief valve 1 in the usual manner. These parts form no part of' the invention and accordingly may be substituted by any'other suitable means 'or organization designed to supplyth'e air and oil requirements of the burner.

The blower is mounted upon and has its discharge open to the interior of a casing 8 which serves as a distributing chamber, which is'connected with the combustion space by a suitable air passage or passages herein conveniently conf stituted by the coaxial pipes I0 and II. The

' outer pipe is directed away from that of the inner one'so that they mingle only as they progress into inner pipe I0 is shown as provided with a flared the combustion space and not im e a y at the pipe outlets.

The oil line 5 passes through the distributing chamber and is arranged centrally of the inner pipe III, terminating adjacent the end of the latter in a nozzle I3 which in this type of burner serves to spray the oil. Slidably mounted on the" oil 5 pipe is a baifle I4, which can be moved forward or backward to decrease or increase the air flow from the distributing chamber to the inner pipe. This is accomplished by a control rod I5 which extends through to the outside of the rear wall 10 of casing 8 where a clamp I5 serves to hold the rod and baflle in any desired position of adjustment. This adjustment is determined so that the air delivered by way of pipe 10 satisfies the normal combustion requirements of the oil dis- 1:; charged by nozzle I3. The fuel is ignited by any suitable means, such as the spark igniter of which ply means and an igniter, which may be arranged or organizedin any desired manner. The air and oil thus delivered to the combustion space are, as usualrin explosive proportions, which is a condi- ..tio"ri incident to clean and emcient burning, and 3G accordingly the mixture is a source of danger under such conditions as the failure of the ignition means, or the inadvertent extinguishment of'the flame while'the igniter is not active. In this event the combustion space rapidly fills with 35 air and oil in explosiveproportions and if the igniter subsequently becomes active, or if the walls of the combustion chamber are sufliciently hot, an explosion results. The inventionavoids this danger'in the following manner: f

A plate I9 'closes the inner endof pipe II except at the lower part ,of casing 8ywhere the latter opens into the pipe. This-opening'is of large size and accordingly" capable of passing al considerable volume of air.; Itis controlled by a'damper 20, the shaft 2| otwhich extends out through the wall of casing 8 When the damper is closed. o is fed through pipe 5 to be sprayed at nozzleJB, the qombustion air passes around the 'edgef of bafilel llfl, and through pipe I0. this being the normal 'combustion conditionfbut when the damper is open'additional air flows from the distributing chamber to the combustion space by way of pipe II and the capacity of the blower and the size of pipe II is; opened, either intentionaily or by the failure of the-current, the-burner is ina condition of safety.

are so designed and related that the volume of air thus passed to the combustion space dilutes the fuel and air mixture sufliciently to render it non-explosive. If the burner is already 5 operating when the damper' is opened the only eifect of the additional air is to lower the temperature of the combustion space. If on the other hand the mixture flowing from the inner tube is not burning, the additional air mingles with it and renders it suflicientlylean as to be non-explosive so that there is no danger even though the fire box Walls are at a fuel igniting temperature as a result of prior combustion. Similarly, there can be no explosion as a result of delayed igniter operation, provided the damper is open, since ignition can only occur at or in the neighborhood of the end of pipe l0 and then only to start the normal burner flame as the fiowing mixture emerges from the inner pipe, the mixture accumulated beyond this region and throughout the fire box and-in the flues being non-explosive, as above explained. The coaxial arrangement of the air supply pipes is not essential but provides a compact construction and a simple arrangement which readily lends itself to the use of a single air source, such as the blower, for supplying both the combustion and the additional air, which is preferred.

The invention also contemplates automatic means. for operating the damper so as to ensure an adjustment appropriate to existing conditions, a simple mechanism for moving the damper being illustrated in Fig. 2.

The damper shaft 2| extends into a control box 22 which is secured to the outside of easing 8, and on top of the box is mounted a solenoid 23 which has an armature extension 24 connected with an army 25 pivoted at 26 to the wall of the box. Arm 25 is connected by link 21 with a crank arm 28 40' which is secured to the damper shaft 2|. The

leads to the solenoid are designated 29.

v the parts are in the position shown in. Flgi zthe solenoid is de-energized and the damp or is open, so that whenever the solenoid circuit Whenthe-solenoid circuit is closed, the armature lifts, raises arm 25 and the latter turns crank arm 26 to close the damper. The solenoid can be controlled in a variety of ways but is preferably arranged to operate coincldently with some suitable control which responds to the initiation and cessation of combus- Fr tionjoperation, controls of this nature, electrical and mechanical, being in common use for opening and closing igniter circuits, operating oil valves and forother purposes. A preferred application of the invention is illustrated by means of the. control system shown in Fig. 3 which em- 60 bodies such a control and which will now be briefly described.

The primary control is in room thermostat 30, the letters R, B and W indicating the so-called red, white and blue lines. For the sake of clear ness the mains 3|, 32 and all high voltage circuits are indicated by heavy lines. A transformer 33 supplies energyto a low voltage pilot relay 34 the circuitof which is directly- 7 controlled, when the apparatus is at rest, by the blue line 35, white line 36 androom thermostat 36. The pilot relay operates a switch 31 in a high The circuit 52, 53 of relay 46 is controlled in this 10 case by a so-called protectostat 54 which is a thermostatic switch device operated by radiant heat. It is so located as to be operated by the burner flame and to move its switch element to closed position under the influence of heat. 15

Solenoid 23 which operates damper 20, is arranged in series with the protectostat and its leads 29 are shown so connected.

Referring to Fig. 2 it will be seen that arm 25.

carries a mercury switch 55. It is so arranged 3 that when the arm'is lifted, which corresponds to the closed position of the damper, the switch is opened. The switch is connected in the blue line circuit 35, as appears from Fig. 3.

When the room thermostat moves to the posi- 25 tion shown, which represents a surrounding temperature condition lower than that desired, pilot v relay 34 is energized through the blue and white elapsed, the time switch 38-49 preferably being of the type requiring to be re-set after operating to shut down the system.

Relay 40 closes red line switch 42 and a switch 43, the latter causing the motor to start and ren- 40, dering active the igniter.

" were it not for the present invention, the safety of the burner at this juncture'would depend solely onprompt ignition, since the blower and oil pump, or whatever supply means are used deliver -san explosive mixture, as above pointed out and reason this non-explosive mixture continues to pass through the, combustion space until element 38 flexes under the influence of heater 39, to break the circuit of relay 40 and so bring the apparatus to rest.

If the igniter functions as intendedprotectostat 54 responds to the radiant heat of the igniter mixture whereupon its switch element closes the circuit of solenoid 23 and relay 46. The energization of the solenoid results in the closure of the damper, as above explained, and since relay 46 operates simultaneously to open switch 41 and so render the igniter inactive, the normal operating condition of the burner is achieved. Switch 46 is also closed by relay 46 to shunt heater 3.9.-

Whent'he solenoid operates to close the damper, it also serves to open mercury switch '55 thereby breaking the blue line and rendering the circuit 76 of pilot relay 34 subject to direct control by red line switch 42, which of course is held closed by relay 40. This latter arrangement in one form or another, is customary in control systems of this type and serves to guard a ainst accident as a 42 opened, so thateven thoughthe white line circuit is 'brokeniimomentarily acomplete recycle with its attendant safeguards is necessary before the burner will re-start. The safety condition produced by the additional air supply and its associated controlling mechanism will be present whenever the burner ceases to operate on its normal combustion cycle. For example, when he burner flame is extinguished, either by stoppage of the motor or otherwise, the protectostat switch breaks the circuit of solenoid 23, permitting its armature to drop and the damper to open. In thesystem illustrated relay 45 coincidently releases switches 41 and 48 which return totheir initial positions respectively to render active the igniter and the time element device 38 39'. This will be recognized as the normal and safe condition which the burner assumes at each starting. Accordingly the circuitconnection to the thermostat, above referred to as the blue line, would remain broken and since the blue line is a part of the starting circuit. through which control the motor circuit and. since the burner mechanism continues in operation after the flame has been extinguished and until brought torest by the timing element 39, it is desirable to delay the closure of ignition switch 41 until the extra air admitted upon the opening of the damper has had an opportunity'to dilute the mixture in the combustion space to a safe condition. Accordingly, with such a system, it is preferred to intrpose a delay, which need not be more than a few seconds, between the opening ofthe damper and' the closure of the ignition switch, which may be accomplished, for example, by a dash pot 'arrangement such as is diagramatically illustrated in Fig. 4. As in Fig. 3, when main relay '45 is deenergized the damperis opened and switches 41 and 48 tend respectively to close and open. The latter. acts promptly, to cut in the heater 39, whereas the ignition switch, delayed by dashpot 56, does not close until somefiv'e secohd'siater, during which interval the extra air passed by the damper will render safe the mixture in the combustion space and in such condition that it cannot explode upon the coming on of the ignition. When, on the other hand, main relay t! is energized, pin an insures that switches 61 and 48 are operated simultaneously;

Subject only to the limitations of the following claims the principles above exemplified can be variously applied to existing installations or otherwise and the burner elements and their controls organized and arranged to suit the conditions in mind.

' In the modified forms of the invention diagram-' matically illustrated in Figs. 5 and 6, 51 indicates any appropriate air conduit leading to the combustion space and subject tocontrol by a damper 58 which in one position (that shown in dotted lines) restricts the air flow, so that the combustion space mixture conforms normal combustion requirements (air and oil being furnished for that purpose by such means as above described or otherwise) and in its other (full line) position, passes the excess air necessary to render the combustion space mixture non-explosive. As indicated, the damper is unbalanced and is adapted to be moved from its open position, established by a stop 59, to its closed position by the air flow through the conduit, being restrained however and permitted to close only when the conditions favorable to an explosion no longer obtain.

In Fig. 5 the damper is coupled to a suitable mechanical timing device 50 which maybe of any preferred construction capable of holding .the damper in its open position for a predetermined interval, which is selected with reference to the setting of the customary safety trip, corresponding to element 38 and its heater 39 in Fig. 3. ,For example, if the safety trip is adjusted to bring the burner to rest after an interval of seconds if ignition does not occur, the timer 60 will be set to release the damper after a somewhat linger interval, say or seconds. In the normal cycle and assuming ignition occurs the damper will thus be closed after the expiration of the .said 110 or 120 seconds but if, on the other hand,

the fuel fails to ignite for any reason the safety trip will act to stop the burner after 90 seconds and the damper will thus'remain in its open'or safe position, ready for the next cycle. As will be apparent, this type of air control is adapted for use with any of the well known or suitable burner systemsembodying a protectostat or equivalent'device acting promptly to stop the burner in response to combustion failure. Switch- 6i corresponds in function to switch 55 above described, being coupled to the damper control so as to open when the damper closes and viceversa, thereby rendering it impossible for the burner to re-cycle until the damper has opened.

In Fig. 6 the damper is held open by a solenoid 23' which is so'controlled as to be energized during the ignition period and to be de-energized in response to combustion of the fuel. For the purpose of illustration the solenoid circuit is shown directly controlled by a heat sensitive device 65, which, as will be understood, includes a normally-closed switch adapted to be opened by the heat of the burner flame, whereuponthe solenoid is de-energized and the damperis released and moved to its closed position by the force of the air blown or sucked through conduit 51. As with the forms of the invention already described, switch 64 constitutes a starting control for the burner and must be closed (and hence the damper open) before the burner can start up. i t

I claim:

1. In. a burner, the combination of two air conduits and means for feeding air therethrough, means for feeding fuel to initially mix with the air delivered through one of said conduits, said one conduit furnishing a supply of air appropriate for normal combustion requirements and the other conduit together with said one conduit furnishing sumcient air to render the combustion space mixture non-explosive, ignition means positioned to ignite the initial mixture, -a damper controlling the flow of air through said other conduit, and means rendered-operative in response to the establishment of combustion to close said damper.

2. In a burner, the combination of two air conduits and means for feeding air therethrough, means for feeding fuel to initially mix with the air delivered through one of said conduits, said one conduit furnishing a supply of air appropriate for normal combustion requirements and the other conduit together with said one conduit furnishing suflicient air to render the'combustion space mixture non-explosive, ignition means positioned to ignite the initial mixture, a damper controlling the flow of air through said other conduit, and means rendered operative in response to the establishment of combustion to close said damper and in response to the cessation of combustion to open said damper, a con- -trol circuit for said ignition means, and means controlling a switch in said ignition circuit adapted to open the same to render the ignition means inactive during normal running of the burner and to close the switch in response to cessation of burner activity, including means for delaying the closure of said switch until after the said opening of the damper.

3. In a burner, the combination of air conduit means and a fan for feeding air therethrough, meansfor feeding fuel at a constant rate tomix with said air in the burner combustion space, a damper controlling the volume of air delivered through'said conduit means to the combustion space, said damper having an open position of excess air, and means rendered operative subsequent to the establishment of combustion to cause said damper to move from its open to its closed position.

4. In a burner, the combination of means for feeding fuel at a substantially constant rate, means for feeding air sufilciently in excess of the combustion requirements to render the combustion space mixture non-explosive, means forigniting the fuel, a safety control device adapted to trip the burner after a pre-determined interv-al, combustion responsive means for rendering by said excess of air, damper means controlling the air delivered to the burner, said damper means adapted to, be'moved by the air to a re- 'stricting position such that the air supply conforms to normal combustion requirementsof the fuel and means for delaying said movement of the damper means until after the establishment of combustion. I

JOHN GOOD.

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