US1928888A - Safety apparatus for oil burners - Google Patents

Description

Gct. 3,1933. w. c. GRoFF SAFETY APPARATUS FOR OIL BURVNERS 2 Sheets-Sheet l Filed Feb. 27, 1930 Oct. 3, 1933. w. c. GRoFF SAFETY APPARATUS Fo OIL BURNERS Filed Feb. 2'1". 1930 2 Sheets-Sheet 2 llOl Llc

/NVA/roe: WML/AM C. @POPE 5)/ l l f/ .35 produce what I- have previously referred to as plosion in the combustion chamber of the ap- Patented Oct. .3, 1933 l UNITED STATES PATENT OFFICE 1,9zs,sss SAFETY APPARATUS `Fon on. BUaNEas william c. cron, st. Loma. Mo.

Application February 27, A1930. Serial No. 431,753 4 0mm. (c1. 175-115) This invention relates to oil `burners and simimy invention is not limited to use with any parlar devices of the type that employ a spark plug, ticular make or kind of electrically-ignited fuel electrodes or other electric spark-producing burner, and further, that various means may means for igniting oil,'gas or other combustible be employed to accomplish the highly desirable 5 mixture used to operate the burner. results attained bylmy invention, such, for ex- Many serious accidents have occurred in burnample, as a short-circuiting device, a shunt, a ers of the general typementioned, due to the condenser, a resistance, a lamp or tube or a gridsparking means failing to create a spark at the leak. In an oil burner of the type herein' illustime the electric motor of the fuel supply means trated an accidental spark that might cause an' l or atomizing means is set in operation, and thereexplosion, can be positively prevented by the use 35 after producing a spark after the combustion of a device or means that will short-circuit the chamber with which the burner is used has behigh tension leads on the transformer or 'the come loaded or overcharged with a.gaseous fuel conductors through which the high tension curmixture. In various makes or kinds of electrirent is carried from.the transformer to the points l cally-ignited oil burnersgthat are now on the of the, sparking means, orby the use of a demarket such a delayed spark isA liable to be provice or means that will ground, shunt or divert duced, in the event of a flame failure or ignition high tension current discharged from the transfailure, when the safety device oftheburner former. The device or means that is used for comes into operation, and opens or interrupts either of the purposes above referred to may be the circuit that supplies electrical energy4 to the arranged externally of the transformer or some transformer of the ignition system and to the other part of the ignition system, or it may be electric motor that drives the fuel pum'p or air built into the transformer or some other part blower. The reason for this is that the electriof the system, so as to form in effect an integral vcal energy which flows into the transformer when portion of said part. If a short circuit devicethe spark plug, electrodes or other spark-prois employed, said device may be designed so that 80 ducing means fails to function properly after it will cause the high tension current to be shortthe fuel pump or air blowerhas been set in circuited either by opening the circuit, or by operation, causes considerable electrical energy closing the circuit, and any suitable or preferred v to be stored up in the transformer, and when means may be used to actuate said device or the supply of electrical energy to the transformer cause it to operate. 85 is subsequently interrupted by the functioning of In view of the multitude of devices or means the safety device of the burner, such stored electhat may be used to prevent the sparking means trical energy will create a faint spark across the of the burner from producing or creating a spark points of the spark plug or electrodes, and thus at a time when such a spark might cause an eX- a delayed spark that will explode the gaseous paratus with which the .burner is used, I will not mixture that has accumulated in the combustion attempt to describe .or enumerate all of the dechamber. vices or means that may be used for this pur- The main object of' my invention is to o verpose. Suiiice it to say that my invention, broad- 95 40 come or eliminate the possibility of accidents of ly stated, consists of an electrically-ignited fuel the kind referred to. To this .end I propose to burner that compriseea spark-producing or creequip an electrically ignited fuel burner with a ating means, 4a transformer or similar apparatus means that will prevent a spark being created for supplyng high tension electric current to said by the spark plug, electrodes or similar means sparking means, a safety device of the kind now of the burner at a time when the combustion generally used in oil burners, or any other suitchamber with which the burner is used is filled, able type or kind, constructed or arranged so as loaded or overcharged withagaseous mixture that to automatically cut off the supply of electric has accumulated in said chamber, due to a current to the transformer in the event of a flame failure, ignition failure or power failure. flame failure, ignition lfailure or power failure, I have herein illustrated my invention. emand a means that will operate automatically in bodied ,in an electrically-ignited oil burner of advance of or prior to theinterruption or cutconventional design, provided with a spark-proting ofl of the energizing circuit of the transducing means composed of' electrodes to which former, for positively preventing high tension a high tension electric current is supplied from current from discharging from or passing from 110 a transformer, but I wish it to b e understood that the transformer to the sparking means.

Figure 1 is adiagrammatic view of an electrically-ignited oil burnerY embodying my invention.

Figure 2 is an enlarged detail, showing the transformer, the time switch, the short-circuiting apparatus and the electrodes; and

Figure 3 is a side elevational view of the shortcircuiting apparatus, showing how thev amature of same-moves automatically -into a position to render the short-circuiting bar operative, whenever the coil of said apparatus becomes de-magn'etizedor de-energized due tofunctioning of the ing apparatus with which the burner is used, and- D designates as an entirety a safety device, such as is now commonly used in oil burners, so as to automatically cut off the supply of electrical energy to the transformer B and motor C in the event of a flame failure or ignition failure. For

example, if the flame fails when the burner is in operation,I the device D will act in such a way as to stop the motor C and lprevent current from flowing into the transformer B. Likewise, if the sparking means A fails to produce a spark when the control switch or thermostat E is actuated to set the motor C in operation, the safety device D will act in a few seconds or in a few minutes to stop the motor and cut off the supply' of cur-r rent to the transformer. During the period the motor C remains in operation prior to the functioning of the safety device D, a considerable quantity of combustible mixture accumulates in the combustion chamber of the apparatus with which the burner is used. A considerable quantity of electrical energy is also stored up in the transformer B during this period, due, of course, to the fact "that there is no electrical discharge from the electrodes A. When the energizing circuit of the transformer is opened or interrupted by functioning of the said safety device, the electrical energy which has been stored up in the transformer is apt to be discharged from the transformer and create a faint spark across the points of the electrodes, and if this occurs, the gaseous mixture in the combustion chamber will be ignited, often with very disastrous results.

In order to remedy or overcome the above described inherent defect of an oil burner equipped with a transformer that supplies high tension electric current to spark-producing means, I prol,pose to equip the burner with a means that will act in advance of or prior to the cutting o3 of the supply of current to the transformer, and operate in such a way as to positively prevent `high tension current from being discharged from the transformer B, or passing from said transformer to the sparking means A. In the burner herein shown. the means just referred to consists of a short-circuiting apparatus F combined with a timing switch G in sucha way that in the event nect the sparking means A with the transformer B will be short-circuited. Various types or kinds.

of timing switches G may be used, so long as said timing switch is installed in the ignition circuit in such a manner and is of such construction that it will act or operate in advance of the safety device D. In the burner herein shown the timing switch G and the short-circuiting apparatus F are of such design (see description of operation) that when the burner is operating normally, or when the motor C is set in operation and the sparking means A functions properly to produce a spark, the short-circuiting bar 2 will be maintained in an inactive or inoperative position, wherein it does not interfere with the passage of the high tension current from the transformer B to the sparking means A. If, however, a flame failure, ignition failure or power failure occurs, the conjoint action of the timing switch G and short-circuiting apparatus F y will render the short-circuiting bar 2 operative before the safety device D causes the supply of electric current to.

the transformer B to be interrupted. Hence, a discharge of high tension current from the transformer, resulting from an interruption of they supply of electrical energy to the transformer, would have absolutely no eiect on the sparking means A, because when such a discharge occurs, the sparking means A is positively cut off from the transformer. It will thus be seen that even though the combustion chamber is filled with a .combustible mixture, `there is no danger of said mixture exploding.

The short-circuiting apparatus herein illustrated consists of a magnet provided with a coil 4 .and with a pivoted armature 5 to which are attached arms 6 that carry the short-circuiting bar 2, which is adapted to co-operate with contacts 'l arranged in the leads 3 between the sparking means A and the transformer B. The timing switch G is connected with the coil 4 in such a way (see description of operation) that under normal operating conditions the coil 4 will be energized, thereby maintaining the armature 5 in.

its inactive or inoperative position, shown in Fig- -ure 3, and causing the short-circuiting bar 2 to be held spaced away from the contacts 7. When the coil 4 becomes de-energized, or de-magne- Itized by functioning of the timing switch G, when a flame failure, ignition failure, or power failure occurs, the armature 5 will swing outwardly into the position shown in full lines in Figure 3 and the short-circuiting bar 2 will move into engagement with the contacts '7, and thus create a dead short across the leads 3 before the safety device' relay opens, and to release the switch for opening Operation The drawings show the position of the parts just after closure of the room thermostat on a .call for heat, with the bimetallic element 4l positioned to the right of the shoulder 42 to prevent opening of the switch 35, and with the stack thermostat or name responsive device open, relay No. 2 de-energized, contact 15 of the starting or energizing circuit of relay No. 1 closed,'and contactA 53 of the circuit for energizing the low tension side of the transformer closed, .it'being understood that these contacts Will be opened on energization of relay No. 2, and that contacts 17 and 59 will be closed. The element R has moved to successively engage contacts W, B, and relay No. 1 is energized through the following circuit: one side of secondary 10 of the transformer, thermal safety switch 11, W, R, B, conductor 12, safety switch 13 (mechanically connected to `element 41 to be opened by 41 as it moves to the Icuit: 27, 23, motor contact 26, 29, one side of motor C, and from the other side by conductor 30 to line 31. At this time, the switch arm 35 of the timing switch is making with contact 36 (being so held by element 41 which is in cold position) and, therefore, coil 4 is energized through the following circuit: 27, 28, motor contact 26, 29, 36, 35, 37, coil 4, 38 to line 3l. -The armature 5 to which are attached the arms 6 which carry the short-circuiting bar 2 is now holding the bar 2 to prevent short-circuiting, it being understood that the armature is biased to automatically move the bar to short-circuiting position, on de-energization of coil 4. At this time the bimetallic element 41 of the timing switch is arranged at the right of the shoulder 42 so that the switch is held against contact 36 or in closed position. The bimetallic element 41 is now being heated and is moving toward the left. At the end of some predetermined period, 41 passes the shoulder 42 and switch arm 35 moves in the direction of the arrow to break contact 36. During motion of 41, contact 13 has been openedand inasmuch as this contact 13 is in the closing or starting circuit of relay No. 1, this relay cannot again be closed until 41 assumes its right-most, or nearly right-most, position. 'Ihe switch 35 opens at the end of about one and one-half minutes and, as a result of this opening, coil 4 is die-energized and the short-circuiting bars move to short-circuiting position so that there can be no sparking across the electrodes of the igniter, although the low tension side of the transformer remains active, When the switch 35y opens, the current to the heating coil 4G aise interrupted and if it were not for the shoulfA der 42, the element 41 (now cooling) would move to the right to assume its original coid position. The eienient 41, therefore, remains at the right and switches 35 and i3 remain open. Under conditions later to be described, when relay No. i

` is rie-energized, switch 35 is automatically raised to closed position so that the eiement 41 can assume the cold position, to itself hold the switch in closed position independently of the switch closing and holding means operated by relay No.1.

Continuing theopemtionf-The opening of switch 35 has occurred because ame was not produced, and the sparking apparatus is now conditioned so that it cannot act. At the end of about a half a minute, after switchfil has moved to open position, heating element 19 which was thermal safety switch 11 to open, and opens the holding circuit for coil 9 so that relay No. 1 is de-energlzed and contacts 25 and 26 are opened. Ordinarily the safety switch has means for locking it in open position, so that the apparatus cannot operate automatically until the switch is manually closed, which is not done until after `energized on closure of the thermostat, causes the inspection and repair of any inoperative elements of the system.

.y Also under this condition of no-flame production, the stack thermostat 50 remains open, the coil 5l of relay No. 2 is not energized, and the switch arms. 16 and 52 remain in engagement with respective contacts 15 and 53. Transformer B is receiving current through the following circuit: 27, 54, 52, 53, 55, transformer B, 56 to line 3l, but although the transformer is thus energized, there is a short circuit across lines 3 and no spark can pass. According to the circuit arrangement just described, the transformer B is always energized except during flame period. This is wasteful, and it is better to de-energize the transformer whenever the motor is de-energized. For this purpose, switch 52 can be connected with line 29, and connection 54 and contact 59 can be dispensed with. In any event, the sparker or ignition means is always rendered inoperative when switch 35 opens. This is an important feature.

It will be noted that even if flame is produced, the switch 35 will open at the end of a predetermined period, because element 40 is being heated by. a circuit which is closed by the motor contact 26. The opening of switch 35, therefore, results in de-energization of coil 40, and 41 begins to cool, but cannot move to its initial right-hand position because of shoulder 42er its equivalent. Motion of the element 41 from the right-most to the left-most position opens switch 13 and breaks the starting or closing circuit of relay No. 1. After opening of switch 35, the shunt for lines 3, 3 is closed so that whatever the electric condition of the transformer B, no sparking at the electrodes can occur to cause explosion. In case flame is produced before safety switch 11 is opened (as the result of prolonged heating of the element 19) relay No. 1 remains energized, the motor remains energized, and iiame responsive switch 50 closes and by this closure, relay No. 2 is energized through the following circuit: 27, 54, coil 51, 57, contact 50, 58 to 31 and as a result, arms' 16, 52 controlled by relay No. 2 move to engage respective contacts 17, 59. The closure of contact 17 shunts out the heating coil 19, the holding circuit for the relay No. 1 then being as follows: 10, 1l, W, R, 60, contact 25, 6l, 18, 16, 17,I 62, 9, 21 to 16. Ey closure of contacts 59, coil i is energized through the following circuit: 27, 54, 52, 59, 63, 37, coil 38 to 3l, and coil 4i) is energized through the following circuit: 27, 54, 52, 59, 63, 37, 43, 40, 4i, to 3l. Thus energiza- .tion of coils aand 40, and open circuit condi tion of lines 3 3 is maintained while flame is present.

Having thus described my invention, what Iv its actuatessaiddevice,andatimingswitchinthe ignition circuit for governing said magnet. adapted to cause said short-circuiting device to be rendered operative to prevent sparkingl in the event ot a name failure, ignition failure or power failure. A

2. A transformer having the usuaihigh tension and low tension circuits, a shunt for the high tension circuit, means for controlling the low tension circuit to open it, and mean acting automatically before opening of the low tension circuit to close the shunt o! the high tension circuit. ,Y Y

3. In an ignition system asparking igniter,

and a transformer, a circuit connecting the ignitter with the high'tension side o! the transformer, means for short-circuiting the high tension circuit to prevent sparking, a timing switch having cuits' for controlling said heating element, and' short-circuiting means through said timing switch.

' WILLIAM C. GROFF.

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