US2688999A - Pot-type oil burner and ignition system therefor - Google Patents

Description

Sept. 14, 1954 R. F, VAN TUBERGEN 2,688,999

POT-TYPE OIL BURNER AND IGNITION SYSTEM THEREFOR Filed Nov. 29, 1949 2 Sheets-Sheet l 24 IJ'IVQTJ'OI" Ill Ti Richard FVEm Tube qen Sept. 14, 1954 R. F. VAN TUBERGEN POT-TYPE OIL. BURNER AND IGNITION SYSTEM THEREFOR Filed Nov. 29, 1949 2 Sheets-Sheet 2 IIYI Rz'c hcf'd Evan Tube gen Patented Sept. 14, 1954 BOT-TYPE OIL BURNER AND IGNITION SYSTEM THEREFOR Richard F. Van Tubergen, Portland, Oreg. Application November 29, 1949, Serial No. 129,941

1 Th present invention relates to an ignition system for controlling automatically the operation of burners consuming oil and other liquid fuels.

In the conventional oil burner, a problem is presented by the tendency of the burner to snuff out because of drafts occurring within the combustion chamber. This problem is particularly acute during the initial period of operation immediately following the lighting of the burner and before the burner and combustion chamber have become thoroughly heated.

Currently manufactured oil burners are provided with a float-operated valve in the conduit conveying fuel to the burner. This is disposed with reference to the floor of the combustion chamber in such a manner that, if the burner is snuffed out, the oil which subsequently accumulates will back up into the float chamber, raising the float, operating the valve, and shutting off the flow of oil. This does not occur, however, until well over an inch of oil has accumulated in the combustion chamber. If the accumulated oil is not removed before relighting the burner, a dangerous conflagration may occur. Also, with the above described mechanism, it is possible to re-ignite a snuffed out burner in the presence of an accumulation of oil while the burner is still hot enough to vaporize some of it with the result that an explosion may occur.

It is a primary object of my invention to provide an igniter for oil burners which will automatically reignite a burner which has been snuffed out thereby preventing the accumulation of oil in the combustion chamber with attendant difliculty of lighting the burner.

It is another important object of my invention to provide an automatic igniter for oil burners which will operate effectively during the period immediately following the initial ignition of the burner, reigniting it immediately if it should become snuffed out.

It is a further object of my invention to provide an automatic igniter for oil burners which may be located out of the combustion zone, thereby materially improving its operation and prolonging its service life.

Still a further important object of my invention is the provision of an automatic igniter for oil burners which is electrically operated but which is provided with means for preventing the ignition of accumulated oil in the event of a power failure.

It is another object of my invention to provide an automatic igniter for oil burners which is Claims. (01. 15828) versatile and may be applied to burners of the various current constructions as well as in the construction of new types of burners.

It is still a further object of my invention to provide an automatic igniter for oil burners which may be placed in operation contemporaneously with the turning on of the fuel supply throug actuation of a single control.

It is still a further object of my invention to provide an igniter for oil burners which is of simple construction and inexpensive to make.

"The manner in which the foregoing and other objects of the present invention are accomplished will be apparent from the following specification and claims considered together with the accompanying drawings wherein:

Figure 1 is a View in elevation, partly in section, of the automatic igniter of my invention applied to the inlet assembly of an oil burner of the class which may be used in the heating of domestic and industrial buildings;

Figure 2 is a schematic view in elevation of the inlet assembly of Figure 1;

Figure 3 is a wiring diagram of the igniter illustrated in Figure 1;

Figures 4 and 5 are detail views of a wick which may be employed in the operation of the igniter illustrated in Figure 1;

Figure 6 is a fragmentary View in elevation partly in section illustrating an alternate construction of an igniter control for use with the igniter of my invention;

Figure '7 is a fragmentary view partly in section illustrating still another embodiment of an igniter control for use with the igniter of my invention;

Figure 8 is a fragmentary view partly in section of still another type of an igniter control for use with an igniter embodying the concept of my invention;

Figure 9 is a fragmentary view partly in section of yet another igniter control ignition system embodying my invention; and

Figure 10 is a fragmentary view partly in section illustrating still a further means for operating the igniter of my invention.

Generally stated, the automatic igniter for oil burners disclosed herein comprises an electric resistance element such as a Nichrome wire placed adjacent the burner and adapted to ignite the same. A switch is placed in an electric circuit with the resistance element and temperature responsive means such as a bimetal blade are placed adjacent the furnace. The bimetal blade actuates the switch, turning it on when the temperature 3 drops below a predetermined level, thereby igniting the burner, and turning it off when the temperature reaches or exceeds the predetermined level. This turns off the igniter until such time as the bimetal blade cools sufliciently to.

close the switch, again establishing the electric circuit through the resistance element. Switch means also may be provided for making and breaking the circuit including the resistance element contemporaneously with the turning on and off of the fuel supply to the burner. Means also may be provided for turning off the igniter in the event of a power failure.

Referring now to Figures 1 to 5;

The automatic igniter of my invention is illustrated applied to a conventional'oil burner comprising the casing Ill having at the bottom thereof an opening II for the introduction of air to the interior. which contains an upper burner ring [3 and a lower burner ring It; and which has an arcuate' A conventional burner 46 is placed adjacent the bottom'of the burner pot. It is supplied with oil through the conduit chamber 18. sembly of conventional construction (Figure 2) including a valve [9 for turning onand off the flow of oil through the conduit 11, a rotatable control shaft 20 for operating the valve, and a float chamber containing a float 21. These elementsare-arranged in such a manner that when oil is admitted to the chamber through conduit 22 by opening valve 24, it accumulates in the chamber until'it has reached a levelat which it may overflow into conduit upon opening of valve I9, whichconveys it to the burner.

The float 2| is attached to a-pivotally mounted arm 23' and is placed at a predetermined elevation above the floor l5 of the burner pot. Upon the accumulation of oil in the latter inthe event of a snuff out of the burner, the level of the oil in the float chamber rises to the level indicated 1 by the dotted line in Figure2 which isthe flood level of the burner pot, thus liftingthe float 2i.

The upward motion of-the floatis used to actuate valve 24 and shut off theflow of oil, preventing. further flooding of the-burner pot. in Well known manner. It also is usedto actuate an extension 23a of arm 23, which extends outwardly from chamber l8 for a purpose to be developed-hereinafter.

Fuel introducedto the burner: it through the line I! isignitedwithin the combustion. chamberv bymeans of suitable ignition means such. as the electric resistance element 25 which:

bottom of the burner pot to'the vicinity of the resistance element. This preferably is made from reinforced'woven asbestos (brake lining) or other porous, noncombustible material. tained in position by means of the holder 27! on which is a knuckle 28 through which extends the resistance element 25. In this manner the wick is supported by and brought into close proximity to the resistance element.

Within the casing is a burner pot i2 l! emanating from the The latter contains an inlet as- It is main-- energized and (lo-energized contemporaneously The Nichrome or other resistance element is incorporated in a suitable electric circuit via electric conductor 30 passing through a plug 3| which is threaded into the casing and extends into the burner pot through aligned openings in the sides thereof. The electric circuit includes a transformer 32 for supplying current at proper voltage to the resistance element 25, anda first electric switch 33' which may be. a mercury switch or a microswitch. The latter is operated by means of the cam follower 34 associated with cam 35 on the shaft 20 by means of which'the flow of oil to the burner is controlled. It will be apparent that when the shaft 20 is rotated to start the flow of oil into the burner the cam'35 will assume the position indicated in dotted outlinein Figure 3, thereby moving the cam follower and closing the switch 33. The motion of the cam follower, however, is against the tension of a spring 36, which will return it to its original position when shaft Ml-is turned to shut off the flow of oil. This breaksthe electric circuit, In

this manner, the resistance element 25 may be with the turning on and shutting off of the-flow of oil to the burner;

A second switch 40, preferably a mercury switch, is in series in the circuit with the first switch and the resistance element. It. has-forits function the breakingof the.- circuit and'conse quent ole-energizing of the resistance element after the burner is in full operation; To this end it is associated with combustion responsive means stationed in the furnacearea, preferably-adjacent the burner pot and designed to respondv to the temperature changes thereof; in such a manner as to open the switch 40 when the:temperaturein. such a manner as to extend approximately to the center of the opening II and in close. prox-- imity to the base l5 of the burnerpot. The spacing of the blade or other, heat responsive element from the burner pot is variable, however, being determined in part by the operating temperature of the burner. Where the burner operates at alow temperature, reaching a maximum temperature of about 500 F., the bimetal blade-may be placed closely adjacent thebottom'of the burner pot. However, where the burner operates at higher temperatures, the distancebetween the bimetal blade and the burner pot may be increased.

It will be apparent that both the burner temperature and the space separating the bimetal blade from the bottom of the burner pot willdetermine the time interval ensuing between lighting of the burner and actuation of the bimetal blade. This, in turn, will determine the length of the period during which the electric resistance member remains energized. In general, the space separating the bimetal blade and the burner pot should be such as to maintain theresistance element energized through the complete vaporization stage of the burner until the latter is in full operation, which usually requires about seven minutes. This insures reignition of the burner if it should be snufiedout duringthe critical initial period.

This is bolted or otherwise.

Similarly, the space between the bimetal blade and the burner pot should be such as to cause closing of switch 40 and ignition of the burner prior to the accumulation of a large amount of oil upon snufling out of the burner after it is in full operation. I have found, however, that the unburned oil entering the burner pot cools the floor of the same rapidly, so that the desired rapid closing of the switch 40 will be achieved. In general the time required to close this switch upon cooling of the burner pot will approximately equal that required to open it upon heating of the burner pot during the initial operating stage.

Actuation of the switch 40, and hence of the electric resistance element is accomplished in the embodiment of Figures 1 to 3 by attaching a mercury switch directly to the bimetal blade and positioning it thereon in such a manner that the switch will be closed when the blade is in its normal position adjacent the burner pot, but open when the blade is displaced by the increasing temperature of the burner pot until it assumes the position shown in dotted outline in Figure 3.

Means also are provided for maintaining the resistance element 25 de-energized when the electric service is resumed after a power failure. This is important, since, if the burner is snuffed out during such power failure, the closing of the switch 40 upon cooling of the bimetal blade cannot energize the resistance element and reignite the burner. As a result, oil will continue to flow through the conduit I! and will accumulate in the bottom of the burner pot. Then if the resistance element 25 Were to become energized upon resumption of the power supply, the ignition of a large quantity of oil would occur.

There is provided, therefore, within the chamber l8 level responsive means such as float 2| operating in conjunction with the valve 24 for turning off the flow of oil when the float reaches a predetermined level determined by the depth of the oil in the bottom of the burner pot. As stated above, the chamber I8 is arranged so that the float 2| is actuated when somewhat over an inch of oil has accumulated in the burner pot. This shuts off the valve 24. At the same time it elevates the arm 23a to the position shown in dotted outline in Figure 3. This opens switch 45 which, like the previously described switches 33 and 40, is in series circuit relationship with the resistance element. Switch 45 will remain open as long as the float 2| remains elevated by the flooding oil. Therefore, when the electric service is resumed, the resistance element 25 will not become energized even though switch 40 has been closed by the cooling of the system and the consequent return of the bimetal blade to its normal position adjacent the bottom of the burner :pot.

For convenience, several of the foregoing elements comprising the ignition device of my inures 6 to 10, inclusive. Thus, as is shown in Figure 6, a spiral 50 of a heat sensitive metal wound on a suitable core and supported on a suitable base 5| may be inserted through an opening in the base of the casing. Upon being heated, the metal comprising the spiral will expand, the resulting motion being used to open a switch 52, corresponding to switch 40 of Figure 3. This will break the circuit and shut off the resistance elevention may be incorporated in a single unit.

Thus the switches 33 and. 45, the transformer 32, and the cam fol-lower 34 with attached spring 36 may conveniently be disposed within a common housing 46 which then may be bolted or otherwise afilxed to the conventional inlet assembly in chamber l8.

Although my invention has been described above with particular reference to the use of a bimetal blade as a heat responsive means for opening and closing the switch 48, it will be apparent that other heat responsive means may also be employed satisfactorily. Some of these and their manner of application are illustrated in Fig-' ment in the manner explained above. However, as the burner cools, the metal spiral will contract, thereby closing the switch and energizing the resistance element. I

Alternatively the temperature responsive means may comprise a fluid actuated device which is responsive to thermal changes. The fluid may be either gaseous or liquid. When gaseous, as illustrated in Figure 7, there may be provided a collapsible bellows 55 filled with air or othersuitable gaseous medium and suspended adjacent the bottom of the fire pot substantially in the middle of the opening I I by means of a bracket 56. Stationed adjacent the bellows and supported by a bracket 51 is a switch 58, which also corresponds to switch 40 of Figure 3. Switch 58 is adapted to be contacted by the bellows as the latter expands under the influence of increased temperature and to break the circuit, thereby turning off the igniter. As the burner pot cools down, however, the bellows will collapse, with the result that switch 58 will close, turning on the igniter.

In the embodiment illustrated in Figure 8, the switch controlling the igniter is actuated by means of the expansion of a liquid. Below the burner pot and adjacent thereto, as by being positioned substantially in the center of the opening H, is a cylinder 60 which is filled with a suitable liquid. The cylinder is supported by means of the bracket 6| attached to the casing 10. An expansible bellows 62 communicates with the cylinder through the conduit 63.. The bellows, conduit and cylinder are filled with liquid. As the temperature of the burner pot increases, the liquid will expand or become partially vaporized, resulting in the expansion of the bellows 62 and the opening of switch 64. This breaks the circuit and ole-energizes the electric resistance unit in the manner explained above. Conversely, as the burner pot cools down, the switch 64 is closed, thereby reopening the circuit through the electric resistance element.

Electrical devices also may be employed as heat responsive elements to control the operation of the igniter. 9, there may be provided adjacent the bottom of the burner pot a thermocouple 65 connected through electrical conductors to the solenoid 66. The latter operates switch 61 which, in turn, controls the circuit containing the igniter. As the temperature of the burner pot rises, the current induced in the thermocouple operates the solenoid 66 which, in turn, opens switch 61, thereby de-energizing the igniter. However, as the burner pot cools down, the switch 61 is closed, as by means of the spring 68 and the circuit then is re-established, thereby re-energizing the. igniter.

Light operated means also may be employed tocontrol the operation of the ignition element. Such means may comprise a photoelectric cell, or alternatively a light actuated unit such as is illustrated in Figure 10. This unit 10 (Mercoid Visaflame) is contained in a tube which penetrates the casing and burner pot ina position Thus as is illustrated in Figure preferably slightly-above the: lower fire .ring- [4. The tube has at its inner end a window through which; the light emanating from the burner passes. It then passes through a bulb contained within the tube which actsto concentrate the light waves on a bimetal coil. The latter being opaque changes the light energy into heat energy. and moves in response to the developed heat. This motion is used to open a switch 12 which, in turn, opens the circuit containing the igniting element and turns it off. However, when the flame within the burner pot is extinguished, the bimetal element moves in the opposite direction, closing the switch 12, re-establishing the circuit, and again energizing the igniting element adjacent the burner.

To summarize the manner of operation of the oil burner igniter of my invention, the control an first is operated to initiate the flow of oil through conduit I! into the burner l6, switch 48 being closed since the burner pot is cold. Contemporaneously, this closes switch 33 through the operation of the cam 35 and cam follower 34. It also closes switch 45 and opens valve 24 through lowering of the oil level in chamber 18. Closing of switches 33 and 45 makes the circuit through the resistance element 25 which becomes sufficiently hot to vaporize oil or other combustible fluid picked up from the floor of the burner potand carried to the vicinity of the resistance element through the wick 26. In this manner, the burner is ignited initially.

The resistance element 25 remains energized until switch 33 is opened manually, or until switch 49 is opened automatically when the temperature within the fire pot has reached a predetermined level. As the temperature of the pot rises with continued operation, this affects a tern-,- perature responsive element, placed adjacent thereto. This element moves with increasing temperature or establishes an electric circuit, the motion or the electric circuit being used to operate switch 49 and to open it. This requires a substantial period of time, e. g. about seven minutes in the operation of the normal burner. During this critical initial period of operation, the igniter remains on so that if snuff. outs occur, the burner will be reignited. instantaneously. i

If, on the other hand, the snuff out should occur after the responsive element has operated to open switch 40 and turn off the igniter, the result will be that the fire pot will cool rapidly because of the cooling eflect of the accumulating oil, closing switch 49 as it does so. This re-establishes the circuit through the igniting element and reignites the burner.

In the event that the snufi out should occur during a' period of power failure or when the circuit through the igniter has been broken accidentally,v the flow of oil will continue into the burnerpot until such time as the flood level in the burner pot is reached 'to cause the float in chamber 58 to be lifted to close valve 24, thereby shutting off the supply of oil to the chamber. At the same time as the float shuts off the supply of oil, it also opens switch 45 through lever arm 23a. This breaks the circuit controlling the igniter, the circuit remaining broken until the surplus oil is removed from the float chamber and burner pot. In this manner, the ignition of the accumulated oil by inadvertent re-energization of the igniter upon resumption of the electric service is prevented.

Hence it will be apparent that, by the present invention, I have provided an automatic igniter for oil? burners I which will reignitev automatically a: burner which has been snufied out, thereby preventing the accumulation of'oil ,inthe' fire pot and attendant diiiiculty-of lightingthe-burner; Furthermore, the igniter of my invention will control the operation of the burner during the critical initial ignition period as well as during the continuing operation of the burner. Still furthenthe presently described oil burner igniter is of simple construction and readily adaptable to the control ,of oil burners of conventional con struction and free from operating hazards even in the event of failure of the power supply.

I-Iaving now described my. invention in preferred embodiments, I claim as new and desire to. protect by Letters Patent:

1. An oil burner system comprising a burner pot, an oil burner therein, manually operated valve means connected to the burner for controlling the flow of oil thereto, electrically operated burner ignition means stationed adjacent, the burner, an oil supply chamber communicating with the burner pot through said valve means, the chamber and the burner pot being stationed relative to each other for communicating a flood levelof oil in the burner pot to the chamber when the valve means is open, an electric circuit including the burner ignition means, electric switch means included in the electric circuit, and level responsive operator means for the switch means operable to deenergize the ignition means upon flooding of the chamber.

-2. An oil burner system comprising a burner pot, an oil burner therein, manually operated valve means connected to the burner for controlling the flow of oil thereto, electrically operated burner ignition means stationed adjacent the burner, an oil supply chamber communicating with the burner pot through said valvemeans, the chamber and the burner pot being stationed relative to each other for communicating a flood level of oil in the burner pot to the chamber when the valve means is open, an electric circuit in: cluding the burner ignition means, first electric, switch means in the electric circuit, level responsive operator means for the first switch meansoperable to deenergize the ignition means upon, flooding of the chamber, second electric switch, means in the electric circuit with the ignition means, and combustion responsive means in heat. exchange relation with the burner pot, the combustion responsive means being operatively associated with the second electric switch meansand operating the same with fluctuations in burner pot temperature.

3. The oil burner system of claim 2 wherein: the combustion responsive means comprises a. thermostat. I

4. An oil burner system comprising a burner pot, an oil burner therein, manually operated valve means connected to the burner for controlling the flow of oil thereto, electrically operated burner ignition means stationed adjacent the burner, an oil supply chamber communicating with the burner pot through said valve means, the chamber and the burner pot being stationed relative to each other for communicating a flood level of oil in the burner pot to the chamber when the valve means is open, an electric circuit including the burner ignition means, first electric switch means in the electric circuit, level responsive operator means forthe first switch means operable to deenergize the ignition means upon flooding of the chamber, second electric switch means in the electric circuit with the, ig-

nition means, and combustion responsive means in heat exchange relation with the bottom of the burner pot, the combustion responsive means being operatively associated with the second electric switch means and operating the same with fluctuations in burner pot temperature.

5. An oil burner system comprising a burner pot, an oil burner therein, manually operated valve means connected to the burner for controlling the fiow of oil thereto, electrically operated burner ignition means stationed adjacent the burner, an oil supply chamber communicating with the burner pot through said valve means, the chamber and the burner pot being stationed relative to each other for communicating a flood level of oil in the burner pot to the chamber when the valve means is open, an electric circuit including the burner ignition means, first electric switch means in the electric circuit, level responsive operator means for the first switch means operable to deenergize the ignition means upon flooding of the chamber, and included in the electric circuit second electric switch means operatively associated with the valve means for 10 operating the ignition means upon operation of the valve means.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,604,492 Smith Oct. 26, 1926 1,703,537 Metcalfe Feb. 26, 1929 5 1,724,132 Hart Aug. 13, 1929 1,780,357 Metcalfe Nov. 4, 1930 2,110,222 Hammers et al Mar. 8, 1938 2,168,859 Bergey Aug. 8, 1939 2,174,818 Brace Oct. 3, 1939 2,416,766 Miller et al Mar. 4, 1947 2,438,823 Resek et a1 Mar. 30, 1948' 2,458,630 Palko Jan. 11, 1949 2,500,663 Cleveland Mar. 14, 1950 2,520,159 Long Aug. 29, 1950 FOREIGN PATENTS Number Country Date 221,107 Switzerland Aug. 17, 1942

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