US1924670A - Oil burner construction - Google Patents

Description

Aug. 2 9, 1933. -w. w. WILLIAMS ET AL 1,924,670

OIL BURNER CONSTRUCTION 3 Sheets-Sheet 1 Filed March 27, '1925 YNN.

r v INVENTORS WWWILLIAMS &,I.E.M CABE ATTORNEY Aug. 29, 1933. w. w. WILLIAMS ET AL 1,924,670

OIL BURNER CONSTRUCTION Filed March 27, 1925 3 Sheets-Sheet 2 15 INVENTORS WWWILLXAMS "Q I.E.M CABF.

ATTORNEY Aug. 29, 1933. 'w. w. WILLIAMSETYAL OIL BURNER CONSTRUCTION Filed March 27, .1925 3 Sheets-Sheet 5 IVENTORS 21 WWWILUAMS z LEYGCABE ATTORNEY Patented Aug. 29, 1933 UNITED STATES PATENT OFFICE on. BURNER CONSTRUCTION Walter W. Williams, Bloomington, and Ira E. McCabe, Chicago, Ill.

Application March 27, 1925. Serial No. 18,654

4 Claims.

vide a safety device to cut off the oil upon the failure or extinguishing of the flame to prevent the flooding and overflowing of the flre pot. It is an object of this invention to provide a double acting safety device having two elements one of which is controlled by the heat of the flame and the other contains a time element so that when the flame becames extinguished, by the particular novel construction of the burner the first element is acted upon almost immediately while the second element may be adjusted to act atany desired predetermined time, thereafter, so that the oil supply will not be cut off immediately but will allow the flame to be reignited before the flre pot floods, in other words, upon a momentary extinguishing and reigniting of the flame the safety device will not operate, however, should it once operate through both elements, the time element must be reset by hand before the burner can function. v 2

is made to the accompanying drawings illustrating a preferred form of this invention, it being understood that the invention is not limited to the exact construction shown and minor detail 3 changes may be made without departing from the scope thereof.

In the drawings: Figure 1 is a view in side elevation, with parts broken away, of an electrically operated oil burner constructed in accordance with this invention, as

applied to a domestic furnace.

Figure 2 is an enlarged detail view in perspective of the fire pot end of this burner.

Figure 3 is a similar view of the thermo coil detached. 4

Figure 4 is rear view of the switch box with the cover removed disclosing the time element member of the safety device.

Figure 5 is an enlarged detail view of the time element member of the safety device.

Figure 6 is a front view of the switch box illustrating the temperature indication of the therm element of the safety device.

Figure 7 is an enlarged detail view of the thermo element of the safety device.

Figure 8 is a diagrammatic viewof the wiring of the burner and safety devices and room thermostat, illustrating the burner, in side elevation, as attached to the furnace.

With these and other objects in view reference The burner operating mechanismcomprisesan encased electric motor 1 having a blower fan mounted in a casing 2 at one end and operated by the motor shaft to force air under pressure through an air conduit 3 leading from the casing through the walls 4 of the furnace to the flre pot 5. An oil pump in a casing 6 is mounted on the other end of the motor shaft to pump oil from a tank or other source, not shown, preferably through a strainer, 7, diaphragm pressure valve 8 and through an oil pipe 9 centrally supported in the air conduit 3 to a nozzle 10 adjacent the fire pot which nozzle is preferably arranged to .impart to the oil emerging therefrom a spiral motion in one direction with a non-rotating vane 11, mounted on the pipe adjacent the nozzle, to impart a spiral movement in the opposite direction to the air from the fan passing thereabout. A spark or induction coil 12 is preferablyarranged upon the motor casing having leads through the air conduit to a spark gap in front of the oil nozzle.

The domestic current is brought in to a switch box 13, preferably mounted on the fan casing and which also preferably contains the time element member 14 of the safety device on the inner side of the box with the thermo member 15 of the device exposed on the other side of the box,as shown. The thermo member 15 includes a Bourdon or pressure tube 16 connected through a tube 17 to a thermo coil 18 of tubing arranged in a casing 19 depending from the fire pot endof the air conduit 3, exposing the coil to the heat from the burner flame and flre pot, the other end 20 of the coil passing backward through the casing 19 and is sealed. A usual thermo liquid is contained in the thermo coil which will cause the Bourdon tube of the safety device to contractor expand in ac--' cordance with the temperature of the flre pot. To prevent the excessive temperature of the fire pot from destroying the thermo coil and also to insure the rapid cooling thereof upon extinquish-- ing of the burner, an air port 21 is arranged in the bottom of the air conduit 3 opening into the thermal coil casing '19 between its rear wall and the coil and is preferably formed by striking up the bottom of the air conduit to provide a baflle 22 to engage a portion of the air from the'fan and'direct it about the coil, as indicated by the arrows in Figure 1. Should the flame fail while the motor still'continues to operate the fan the cold fresh air from the air conduit directed about and passing through will cool the coil very quickly causing the Bourdon tube of the safety device to contract correspondingly.

Acting in conjunction with the thermo element 15 of the safety device is the time element 14 which when once operated breaks the circuit from the commercial line through the motor and cuts off the supply of oil to the burner until reset by hand.

The diagrammatical layout of the circuit shown in Figure 8 clearly illustrates the operation of the double element safety device. The commercial circuit leads 23 and 24 are brought to the terminals of the knife switch 25 in the switch box 13 which switch when closed connects lead 23 to one terminal of the motor 1 and the other lead 24 to and through a room thermostat 26, placed where desired to control the temperature of the building, thence to and through a boiler control 27 connected with the inside of the furnace, or interior of the boiler in hot water systems, and thence to and through the safety device, hereinafter described in detail, to the other terminal of the motor to complete the circuit. Therefore the opening of the knife switch 25, or the operation of either of the room thermostat, boiler control or safety device will break the circuit through the motor to cut off the oil supply which is furnished to the nozzle by the motor operated oil pump, however, the burner will again ignite upon closing the knife switch or the operation of the room thermostat or boiler control when conditions resume the normal but the safety device must be operated manually after breaking the circuit, before the motor can be again placed in circuit, The room thermostat and boiler control may be of any desired form but in this case are illustrated as being constructed in accordance with the McCabe devices as disclosed in his prior applications Serial Nos. 538,916; 585,698; and 596,408, filed February 24, 1922; September 1, 1922; and October 23, 1922, respectively. Furthermore, the spark or induction coil may likewise be of any desired type but is shown herein as being in shunt circuit from the motor so that while the motor is in circuit the ignition will continue to spark.

The two elements 14 and 15 forming the safety device comprise a time element in the casing 14 and include a mercury tilting switch tube 30 having two terminals near one end so that when the tube is tilted, as shown in full lines in Figures 5 and 8, the circuitwill be closed between the terminals by the mercury in the tube. One terminal is connected to the lead 24 of the commercial current, as shownin Figure 8, and the other terminal through a flexible lead 31 to a binding post 32 on the casing. The tube 30 is carried on a plate 33 pivoted to the casing and having a pawl like projection 34 depending therefromwadapted to be engaged by the teeth of a ratchet wheel 35 carried on a stem 36 mounted in a cup 37-containing solder about which cup a wire 38 from the binding post 32 is wrapped and thereafter is attached to the binding post 39 on the casing. A weight 40 is carried on the tube supporting plate normally acting as a positive means to tilt the tube to cause the mercury tobreak the circuit in case the spring 41, provided between the pivoted plate and casing to normally throw the tube to open position, fails or deteriorates. The dotted lines in Figure 5 illustrate the position of the tube when the circuit through the motor is broken and the pawl 34 has passed out of engagement with the ratchet wheel 35. When the switch has been set to close the circuit by de-.

pressing. the pawl so it may pass the ratchet wheel andv the tube tilted until it will engage in the teeth thereof, as shown in full lines in Figure 5, the tube will be held by the cold solder in the cup 37 until the heat generated by the current passing through lead 38 will be sufiicient to melt the solder and allow the weight on the tube to rotate the ratchet'wheel to free the tube plate pawl. This arrangement forms the time element of the safety device and can be regulated by the number of coils of the lead 38 about the cup 37. The lead 24 of the commercial current passes from binding post 39 to the motor 1.

A shunt circuit is provided by lead 50 from binding post 32 of member 14 through the thermal element 15 and back to binding post 39 and is of such a character that when the circuit'is closed through the thermal element 15 the majority of the current from lead 24 will pass therethrough to the motor and insufficient current from lead 24 will pass through the time element to melt the solder and when the circuit through the thermal element is broken all of the current fromthe commercial line will pass through the time element and about the solder cup which will be sufl'icient to generate enough heat to melt the solderto free the tube pawl and allow the weight to tilt the tube and break the circuit to the motor. It is therefore seen that the operation of the thermal element controls the operation of the time element. v

The operation of the thermal element in turn is controlled by the heat from the burner flame and fire pot. The thermal element includes a tilting mercury switch tube 30 having two termirials adjacent one end which are respectively connected to the binding posts 32 and 39 of the time element by the leads 50, and is operated by the Bourdon tube 16 to throw the tube over with a snap action as disclosed in the McCabe prior application above referred to.

Briefly, the switch tube is mounted on a carrier plate pivoted to the casing 15, the free end of the Bourdon tube is connected by a pivoted link 51 intermediate the ends of an operating lever 52 pivoted at its upper end to the casing and connected adjacent its free end by a pivoted link 53 to a throwing arm 54 adapted upon movement in the direction carried by the expansion of the Bourdon tube to throw the switch tube to cause the mercury therein to close the circuit through its terminals and upon movement in the direction caused by the contraction of the Bourdon tube to throw the switch tube in the opposite direction and break the circuit through its terminals. The Bourdon tube being in connection with the thermal coil 18 is caused to expand or straighten out as the temperature of the coil is increased by the heat from the flame and fire pot and likewise is caused to contract very rapidly upon failure of the burner flame and the passage of thecold air from the air-conduit forced about the coil 18. The pivotal connection between the link 53 and the throw arm 54 includes a pivot pin 55 mounted on the link adapted to engage in a slot in the throw arm so-as to have a sliding contact therewith and also in a slot in the link normally held in contact with the inner end of this slot by a spring 7 56 attached to the pivot pin and link which upon expansion of the Bourdon tube beyond that sufficient to throw the switch will cause the tension of the spring to be overcome and allow further movement of the link until the pivot pin 55 is engaged by the outer end of the link slot. It is preferable to provide a pointer57 on the free end of the operating lever 52 adapted to travel over a graduated dial 58 carried by the switch tube plate and which moves therewith. The spring 56 between the pivot pin 55 and link 53 having a sliding connection therewith is calibrated and the dial 58 over which the indicator 57 on the free endof the operating arm 52 travels is subdivided to indicate temperatures above that which throws the switch tube. As seen in Figure 6, the outer surface of the casing 15 is provided with an opening through which the dial and indicator is visible and the temperature of the fire pot will be indicated when the burner is operating. Experiments have proved that the .burner will operate most efllciently and economically between certain temperatures so that by observing the temperature of the fire pot as indicated on the dial the oil inlet valve may be adjusted to produce the most economical operation of the burner.

Referring to the wiring diagram of Figure 8, the operation is as follows: Upon closing the switch 25 with the time element set in operating position, the commercial current passes through the room thermostat 26 and the boiler control 27 to the time element which having been set in closing position allows the current to pass through the switch tube and through the lead 38 about the solder cup and thence to one terminal of the motor, the thermal coil being cool the thermal switch will be in the open position, the current passing through the motor to the other terminal connected to lead 23 of the commercial current completes the circuit which will cause the motor to operate the air fan and oil pump and'at the same time the spark coil of the ignition so that the flame at the nozzle will be immediately ignited. The time element has been so regulated, as above described, that the heat from the burner and fire pot will have caused the temperature of the thermal coil 18 to rise suificiently to throw the switch of the thermal element to closed position before suflicient current has passed about the solder cup to free the time element switch, and thereafter as long as the burner flame remains ignited the majority of the current will pass through the thermal element switch. The operation of the room thermostat or boiler control will break the circuit and cause the motor to stop which immediately cuts off the supply of oil to the burner through the oil pump and air from the fan which results in the cooling of the thermal coil causing the Bcurdon tube to throw the thermal element switch to open position but as the circuit is broken it does not effect the time element of the safety switch so that upon the operation of the room thermostat or boiler control to resume the completion of the circuit the parts will operate as described when the knife switch is closed to complete thecircuit.

However, upon the failure of the burner flame, from any cause whatever, while the motor is operating the immediate drop in temperature of the thermal coil causedby the cool air from the fan passing through and about it will cause the Bourdon tube of the thermal element switch to contract and break the circuit through that tilting mercury switchtube causingall of the current to then pass through the time element. Upon a continued failure of the burner flame the current passing through lead 38 about the solder cup will free the time element switch to operate to 'ment switch will be closed, asfirst described,-

and the majority of the current will pass therethrough as before. The windings of the lead '38 about the solder cup of thetime element by beof heat produced when all of the current passes therethrough which in turn will determine the amount of time consumed between the breaking of the circuit through the thermal element and the melting of the solder to allow the time element switch to operate to break the circuit through the motor.

The combination of the double element switch, that is the switch with the thermal controlled and time controlled elements, with the thermal coil acted'upon by the heat produced at the burner and in the fire pot produces a novel safety device entirely complete in itself, positive in action, and operating to. cut off the oil supply in a much shorter time than heretofore accomplished. It is recognized that thermal coils or bars have been employed as stack controls, that is, arranged in the stack or otherwise located to be subjected to the heat of combustion of the liquid fuel, which as the heat is produced will close an electric circuit or otherwise release the fuel supply to the'burner and upon the decrease or failure of the heat of combustion break the circuit or otherwise cut off the supply of fuel to the burner, but such devices take a great length of time to operate on account of the slow dispersion of the heat of combustion when the burner flame fails. The placing of the thermal coil at the entrance to the fire pot where it is subjected directly to the-heat from the burner causes it to be effected quickly uponthe ignition of the flame and the passage of the air from the fan about the coil when the burner is extinguished causes it to cool quickly. Without the time element in combination with the thermal operated switch the latter would have to be manually reset each time it operated, in other Words, each time the room thermostat or switch would be thrown to open position and before the burner could operate after the roomthermostat or boiler-control had operated to close the circuit it would require to be manually thrown to closed position. The time element is necessary to the operation of the safety device with the sensitive thermal element and the sensitive thermal element is necessary to the prompt operation of the safety device.

What we claim is:

1. In a fluid fuel burner construction including an electric motor operating a fuel pump and fan blower with an air conduit leading from the blower to the furnace and a fuel pipe leading from the pump passing through the conduit terminating in a nozzle at the open end of said conduit, a double unit safety switch in the motor circuit, one unit having an actuating thermal element to make'and break the circuit through said unit upon ignition and failure of the burner flame, respectively, said thermal unit including a tubular member connected to said unit and terminating in a coil arranged on the exterior of the air conduit adjacent the furnace end thereof, a housing about said coil having an opei end adapted -to enter the furnace, and means upon the air conduit for deflecting a portion of the air therefrom to pass through the said housing over the coil into the furnace, the other element comprising a manually operable switch to close the motor circuit therethrough, a thermal device for holding it in closed position, a shunt circuit, a heating element in said shunt circuit adapted, when the main circuit is broken through the first unit, to receive the full current of the motor circuit to operate the heating element to release the latter switch to break the motor circuit.

2. A fluid fuel burner construction including an electric motor operating a fuel pump and a fan blower with an air conduit leading from the blower to the furnace and a fuel pipe leading from the pump through the air conduit terminating in a nozzle at the open end thereof, a safety device in circuit with the motor comprising the combination of a safety switch, means for normally holding it in open position, a thermally releasable means for holding the switch when manually moved to closed position, a shunt circuit, a heat generator therein adapted to be actuated by the full motor circuit to release the said holding means, a sensitive control for said heat generator in the motor circuit having a thermal element to close the circuit promptly upon ignition of the burner flame before the full motor circuit passing through the shunt releases the switch and upon failure of the burner flame to promptly break the circuit through the control and cause the full motor circuit to pass through the shunt to release the switch and break the motor circuit, said thermal element extending from the control and terminating at a point adjacent the furnace end of the air conduit and arranged upon the exterior thereof, a housing about said termination having an open end adapted to enter the furnace and means upon the air conduit for deflectinga portion of the air therefrom to pass through the housing over the termination of the thermal element into the furnace.

3. A fluid fuel burner construction including an electric motor operating a fuel pump and a fan blower with an air conduit leading from the blower to the furnace and a fuel pipe leading from the pump passing through the air conduit terminating in-the nozzle in the open end of said conduit, in combination with a thermostat in the motor circuit for controlling the normal operation thereof and a double unit safety device including a switchin each unit in series with eachother in the motor circuit, one of which units being provided with an actuating thermal element terminating in a coil arranged exteriorly of and adjacent the open end of the air conduit, a housing about said coil having an open end adapted to enter the furnace and means upon the air conduit for deflecting a portion of the air therefrom to pass through the housing of the coil into the furnace, said thermal element adapted to make and break the circuit through said unit upon the ignition and failure of the burner flame respectively, the other element comprising a manually operable switch to close the motor circuit, a thermal device for holding it-in closed position, a shunt circuit having a generator therein adapted when the circuit is broken through the first unit and the full motor current passes through the shunt to operate its thermal element to release the switch of the latter unit and break themotor circuit.

4. In a fluid fuel burner construction including 7 an electric motor operating a fuel pump and a fan blower with an air conduit leading from the blower to the furnace and a fuel'pipe leading from the pump, passing through the air conduit terminating in a nozzle at the open end of said conduit, a safety device inserted with the motor comprising the combination of a safety switch in the motor circuit adapted normally to assume the open position, a thermal means for holding the switch in closed position, a heat generator adapt- 100 ed to actuate the thermal holding means to release the switch when the full motor circuit passes therethrough, a shunt circuit about said generator, a sensitive control therefor comprising a second switch in the shunt circuit, a thermal eleme'nt terminating in a coil upon the exterior of the air conduit adjacent its open end having a housing thereabout mounted upon the air conduit and a portion of the air conduit therein struck inward to deflect a portion of the air pass- 110 ing therethrough into the housing and over the coil, said thermal element adapted to operate the second switch to close the motor circuit therethrough promptly upon ignition of the burner before the full motor circuit passing through the 115 shunt releases the first switch and upon failure of the burner flame to promptly break the circuit through the second switch and cause the full motor circuit to actuate the heat generatorto release the first switch to break the motor circuit.

WALTER W. WILLIAMS. IRA E. McCABE.

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