US2440405A - Combustion responsive fuel control - Google Patents

Description

April 27, 1948) R. W. JOHNSON COMBUSTION RESPONSIVE FUEL CONTROL Filed Aug. 5l, 1944 Patented Apr. 27, 1948 UNITED STATES PATENT OFFICE COMBUSTION IRESPONSIVE FUEL CONTROL Roy W. Johnson, Milwaukee, Wis.

Application August 31, 1944, Serial No. 552,168

This invention relates to improvements in devices for controlling the ow of fuel to a burner and particularly to means for closing the inlet valve of such devices if the burner flame is not ignited or is extinguished for any reason.

One of the objects of the present invention is to provide a fuel flow control device in which the inlet valve thereof is closed upon failure to ignite fuel supplied to a burner or upon extinguishment of the fire after ignition thereof.

Another object of the invention is to provide fuel flow control means in which'the inlet valve is automatically closed responsive to the tempera.- ture of the burner.

Another object of the invention is to provide temperature-responsive means for controlling the flow of fuel to a burner, which means will simple means which may be readily combined with a liquid fuel flow control device of the constant level type for preventing flooding of a heater burner by controlling the inlet valve for such devices free from interference with the normal control means for th'e inlet valve or with other safety shut-off means for such valves".

A further object of the invention is to provide a safety shut-off device for mechanisms controlclaims. I.(cl. 15s-2s) the present device are connected and on which some of such electrical portions are mounted:

Fig. 3 is a bottom plan view of the terminall board on which portions of the electrical elements of the present invention are mounted; 1

Fig. 4 is a fragmentary view partially in section showing the construction of one of the electrical elements of the device;

Fig. 5 is a diagrammatic view showing the interconnection of the electrical elements of the present invention; and i I Fig. 6 is an enlarged detailed view of portions of the structure illustrated in Fig. 1 and shown diametricallyinFlg. 5.

Referring to the drawing by reference numerals, the numeral 6 designates a casing defining a main chamberl 'I to which liquid fuel flows by way of an inlet conduit indicated at 8 and an inlet'passage in the main chamber under the control of an inlet valve which' comprises a tug bular valve casing Il placed in the inlet passage compressed against the spring seat I4 by a washling the flow of liquid fuel to a burner in which i the device is simple in its construction, reliable and durable in operation, and easy and inexpen-v the structural relationship of the pot with aA structure embodying the present invention;

Fig. 2 is a top plan view of a board bearing the terminals to which the electrical portions of and formed with discharge passages transverse to the axial passage and with an interior shoulder forming a seat for a valve I2. The inlet valve I2 is shown-as being of the needle type slidably fitting in the upper portion of the valve casing II and as having an exteriorly threaded, flanged sleeve I 3 secured on the upper portion thereof. A flanged member I4 seats on the flange of the sleeve I3 and provides a seat for a spring I 5 er I6 and a nut I1 threaded on the sleeve I3, the spring I5 sewing as means for retaining the nut II in a predetermined position. The valve casing II is surrounded by a spring I8 acting between a shoulder on the valve casing and the underside of the spring seat I4 to bias the valve upwardly away from its seat and into an open position.

The degree to which th'e inlet valve I2 is opened by the spring I8 is determined by a float, 2I having a lever 22 extending therefrom and pivotally mounted intermediate its ends on a bracket y23 in the casing 6, the end of the lever beyond the pivoting point thereof being bifurcated and bearing on the washer I6 on two sides of the nut Il. Thus, rise in the level of th'e liquid in the chamber 'I rocks the float 2I about its pivot so that the end of the lever bearing on the washer I6 pushes the inlet valve toward the closed position as the liquid level rises. Above a predetermined level in the chamber 'I the oat 2| completely closes the inlet valve during normal operation of the device. l

However, even though precautions are usually taken to supply only fuei free from grit, etc., the inlet valve l2 may be held on its seat for some reason in spite of the action of the float 2| in urging the valve toward its seat. Under such circumstances the level of the fuel in the chamber 1 continues to ri'se until the fuel flows over a partition 26 extending across the casing. 6 and forming an auxiliary chamber 21 which contains a float 28. The auxiliary float 28 is pivotally connected with a lever 29 also pivotally mounted on the bracket 23 and having the end thereof ad- Jacentthe pivot formed to act as a latch for a mechanism ,for forcibly closing the inlet valve upon release of the mechanism. The valveclosing mechanism includes a plate member 32 pivoted on the bracket 23 and formed with a handle 33 extending outside of the casing 6 and with an extension bearing aweight 35 in the chamber 1. A spring 36 interconnects the bracket 23 and the plate 32 to assist the weight 35 in biasing the plate 32 downwardly for contact with the nut |1 and hence the valve I2. When the auxiliary fioat 28 is positioned as' shown in Fig. l in the drawing, the end of its lever 29 engages the plate 32 and latches the plate in raised position against the downward biasing of the weight 35 and the spring 36. If the inlet valve l2 sticks in open position, the liquid level in chamber 21 raises the iioat 28 to release the end ofits lever 23 from the plate 32. The weight'35 and the spring 36 then snap the plate 32 downwardly to strike on the nut |1 and to force the inlet valve I2 into closed position. Y

Fuel is supplied from the main chamber 1 by way of a conduit 4| to a pot or other fuel-burning device indicated at 42, under the control of a metering valve, generally indicated herein at 43, and preferably such as disclosed for example in Patent 2,293,903. granted to me on August 25, 1942, in which a tubular guide with an internal seat is tted into an outlet passage in the casing 1 to receive a tubular valve slidable in the guide and controlling the ow of fuel by means of a slot through the valve, which slot is exposed to the fuel in the supply chamber above the metering valve guide seat. The metering valve is biased toward open position by a spring 44 to a degree which may be determined by adjusting a manually operable knob 45 acting, through a cam structure, disclosed in the above patent, on a pin 46 in vertical alinement with the metering valve 43, as is also described in the above patent.

The position of the metering valve 43 may also be controlled by thermostatically operated means acting on the valve through a leverage now to be described. A pin 50 extends through the top of the casing 6 and, at its lower end, has a head resting on one arm of a lever pivotally mounted in the casing and having a second arm, designated 52, and oilset to one side of the arm 5|.

. The lever arm 5| overlies an arm 53 of stiiily resilient material xed at one end in the casing, as indicated at 54, and engaged near its other end by an adjusting screw 55 so mounted in the casing as to be capable of swiveling in its seat. The adjusting screw 55 iiexes the arm 53 upwardly or downwardly so that variations in grade of the fuel may be compensated. The lever arm 52 is provided at its free end with` a threaded opening receiving a slotted screw 56 bearing on the free end of the resilient arm 53 to compensate for changes in oil viscosity and thus determine the low or pilot-fire position of the metering valve. The lever arm 52 also has a leaf-spring 51 connected thereto and extending over the end of the metering valve 43 and engaging therewith under certain adjustments of the above leverage. A bimetallic strip 58 is also fixed at one end to the end of the lever 52 bearing leaf spring 51 and underlies such spring. The bimetal modies the action of the spring in response to temperature changes and thus compensates for oil viscosity changes due to temperature changes.

In themanual control of the metering valve 43, the knob 45 is adjusted to extend the pin 45 through a hole in the lever arm 52 until the pin bears on the spring strip I51 through which the pin acts on the metering valve to adjust the position thereof. Such adjustment of the valve may be continued until the lever arm 52 brings the screw 56 into engagement with the end of the resilient arm 53 to the low or pilot-fire position determined by adjustment of the screw 58. Further adjustment of the knob then flexes spring 51 to close metering valve 43 completely at which time the spring also rests on bimetal 58.

The valve-operating leverage above described is actuated by a controlling unit mounted on the casingl 6 and acting on the pin 5l). A control casing bottom portion 60 is mounted on the main casing 6 and supports a terminal board or panel 6| preferably of both electrical and heat-insulating material spaced from the control casing bottom 60. The terminal board is provided with a plurality of terminals 62 to 61, inclusive, for connection with electrical conductors and has mounted on the upper surface thereof a transformer 68. A heat motor preferably comprising 'a bimetallic strip 1| and an electrical heating element 12 of any suitable type, mounted in heatconducting and electrical insulating relation on the bimetal 1I, is secured on the under side of the board 6| and preferably in heat-insulated relation, as indicated at 13. The bimetal 1l has fixed on one end thereof an extension 14, which is preferably of heat-insulating material, for engaging the pin 50. The portion of the extension beyond the casing 60 is partially enclosed by a guard 15 to prevent interference with movement of the vheat motor. And the entire control unit is covered by a top casing 16 fitting over the bottom casing 80.

A second heat motor, including a bimetallic I strip 18 and a heater 19, is fixed on the under side of the terminal board 6I, as at 80. 'I'he bimetal 18 extends over the inlet valve I2 in such position as to be engageable with an extension 8|r from the valve, and the end of the blmetal extends into a position such that the curled end thereof may engage a notch in a lever 82 to serve as a latch for holding the lever in predetermined position so long as the bimetal is cold. The lever or handle 82 carries a contact 83 engageable with a contact 84 mounted on the terminal board, the two contacts forming a starting switch for some of the electrical elements of the device. as will appear hereinafter.

In 'addition to the switch 82, 83, 84 controlling energization of portions of the electrical elements of the device, a thermostat is provided, as is diagrammatically indicated at in Figure 5, for mounting in a space in which the temperature is to be controlled. and operating in conjunction with a thermally actuated limit switch. The limit switch, which is preferably formed as a bitmetallic strip 9| is xed, as at 92, on the burner pot 42 with an electrical contact 93 mounted on the strip and a cooperating contact 94 xed on the -side of the pot, Electric current is supplied to the s electrical elements of the device from a suitable power line. designated at 96 and indicated as being the usual 11o-volt line available in residences, It will be understood, of course, that current may also be supplied to the usual hot-air circulating fan or a draft fan (not shown) by way of connections 91.

The interconnections of the various elements forming the electrically energized portions of the device, and the action of the heat motors, can be best seen by reference to the diagram in Fig. 5. The transformer 88 is 'always 4connected, to the electric line 98 and is always energized. Consequently, closure of the thermostat 90, when more heat is required, completes a circuit through the heater 12 which heats the bimetal 1I to warp the extension thereof up from the pin 50. Such pin lifts upwardly to permit the metering valve 43 to supply more fuel. The terminals of the transformer 68 are severally connected through bimetallic strip 9| to contact 93 and to contact 94. If the temperature of the pot 42 rises to a sufllcient value, the bimetal 9| warps to close contacts 93 and 94 which complete a circuit through. the heater 19 togheat the bimetal 18 which is designed to warp upwardly away from the inlet valve extension 8| when heated and to flex toward the valve extension when cooled, 'Ihe notch'85 in the starting switch handle 82 is engageable with the endv of the bimetal 18, as shown in Fig. 5, when the switch ls closed, and disengages from such handle when the switch is opened, as shown in Fig. 6.

The operation of the device will be clear from the following description. The inlet valve closing member 32 is raised by lifting the handle 33. 'I'he chamber28 then being empty, the float lever 29 latches the plate 32 in raised position. The spring I8 can then open the inlet valve I2 and fuel flows into the chamber 1 under the control of the float 2i. The switch handle 82 is lifted to close the contacts 83, 84 so that electric current flows from the transformer 68 through the heater 19 to commence heating the bimetal 18.

Contacts 83 -and 84 are held closed by engagement of the end of the bimetal 18 in the notch of the handle 82 so long' as the bimetal is below a predetermined temperature. The metering valve 43 is then manually set to a position so that oil may flow to the pot 42 at a desired rate where it is ignited to maintain a desired temperature in the space to be heated, As soon as the pot 42 reaches a predetermined temperature, the thermal switch contacts 93, 94, close to complete another circuit to the heater 19. As soon as the bimetallic 18 is sufficiently heated to warp upwardly and release the switch handle 82, the handle drops to open the circuit completed by the contacts 83, 84. The device is now in full operation with the thermal switch 9|, 93, 94 controlling the heater 19 and actuating the bimetal 18.

If all of the above described starting steps are performed exceptin-g igniting of the oil in the potv 42, closure of the switch 82, 83, 84, with the latching thereof by the bimetal 18, causes the heater 19 to warp the bimetal 18 upwardly which releases switch handle 82 and allows the starting switch to reopen. The bimetal 18 then cools and pushes the inlet valve to closed position before the pot can be flooded. If the fuel in the pot 42 is extinguished for any reason, the thermal limit switch 9|, 93, 94 opens and the heater 19 cools down so that the bimetal 18 returns to the position shown in Fig. 1 and presses the inlet valve l2 towards closed position until the starting 6 f4 switch 82, 88, 84 is again lifted. It will be apparentfrom the above description that the fire Dot cannot be flooded, either by failure to ignite the oil supplied thereto upon starting of the system or by extingulshment of the fire after starting, for any reason whatever.

Although but one embodiment of the present invention has been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

1. In a device for controlling the flow of fuel to a'burner, an inlet valve controlling the supply of fuel and biased toward open position, a

bimetallic element movable into position to close the valve, an electric heating element for supplying heat to warp the bimetallic element away lfrom valve-closing position, a plurality of circuits for supplying electric current to the heating element, a manually operable switch closing one of the circuits to the heating element, the bimetallic element engaging and retaining the manually operable switch in closed position for a predetermined time after energizationof the heating element, and a thermally responsive switch for closing another of said circuits to the heating element to hold the blmetallic element out of valve-closing position after opening of the manuallyoperable switch, .the thermally responsive switch closing on combustion and opening upon non-combustion of fuel in the burner.

2. In a device for controlling the flow of fuel to a burner, an inlet valve for controlling the supply of fuel and biased toward open position, a bimetallic element movable into position to close the valve, an electric heating element for supplying heat to warp the bimetallic element away from valve-closing position, a plurality of cir-l cuits for supplying electric currentto the heating element, a switch having a manually operf valve-closing position after opening of the manually operated'switch.

3. In a device for controlling the flow of fuelresponsive element, and a hot-.closed combus-l tion-responsive switch controlling another of the circuits and opening responsive to temperature changes resulting from interruption of fuel combustion in the burner.

4. In a device for controlling the flow of fuel into a burner, an inlet valve urged toward open position and controlling the flow of fuel into the device, a thermally responsive element urging the valve toward closed position when unheated, an electrically energized heater moving the element out oi' valve closing position when energized, a plurality of electric circuits for energizing the heater upon closure of any one of the circuits, a manually closed and gravity opened switch controlling one of the circuits. the end of the thermally responsive element engaging and holding the switch closed for a predetermined time after energization of the heater, and a hot-closed com bustion-responsive switch controlling another of the circuits and opening responsive to temperature ,changes resulting from interruption of fuel combustion in the burner.

5. In a device for controlling the flow of fuel to a burner, an inlet valve biased toward open position and controlling the flow of fuel into the device, a heat motor urging the valve toward closed position when deenergized, a, plurality of electric circuits for supplying energy to the motor for actuation thereof, a manually actuated switch controlling the closing of one circuit. the switch being held closed by the heat motor for a predetermined time after energization and REFERENCES CITED The following references are of record in the ille of this patent:

UNITED STATES PATENTS Number Name Date 1,992,561. Williams Nov. 27, 1934 2,049,960 Jones et al. Aug. 4, 1936 2,323,767 Hammond July 6, 1943 2,355,436 Hayter Aug. 8, 1944 2,416,766 Miller et al. Mar. 4, 1947 FOREIGN PATENTS Number Country Date '155,379 France Nov.V 23, 1933

Images