US2753931A - Gas-burner control system - Google Patents

Description

y 1956 w. A. RAY 2,753,931

GAS BURNER CONTROL SYSTEM Filed Jan. 28, 1952 P IE 5 L76 1/ ZSnventor,

MLL/AM K). PAY

United States PatentO GAS-BURNER CONTROL SYSTEM.

William A. Ray, North Hollywood, Calif., assignor to General Controls (30., Glendale, Calif., a corporan'on of California Application January 28, 1952, Serial No. 268,611 1 Claim. (Cl. 158-123) This invention relates to electrically controlled gasburner control systems, and more particularly to such systems which employ gas-supply valves whose normal operation depends on electric power supplied by the service companies. Inasmuch as supply of such external power is subject to periodic failure or interruption, it has been customary to provide means for then opening the gas-supply valve manually. But by so doing any safety means in the system depending on the external electric power are rendered ineffective, and dangerous conditions may result if the power failure is of more than brief duration. As an improvement, a source of electricity independent of the external service may be provided for operating the gas-supply valve, as by thermoelectric means heated by an auxiliary gas-burner; however, an arrangement of that kind is unsuitable when used in conjunction with other means operable only by external electric power, such as a motor-driven device for circulating a medium such as air or water heated by the gas burner, since in the event of failure of the'external power the operation of the burner is unaffected although withdrawal of heat by the circulating means has ceased.

With the foregoing in view, it is an object of this invention to provide an improved gas-burner control system whose normal operation is under the control of means energized by external electric power (so that operation of the burner is immediately interrupted in the event of failure of that power) and having manually operable means for then supplying gas to the burner; my improved system including thermoelectrically energized means cooperating with the means normally energized by the external electric power, the thermoelectric means being arranged to effect shut-off of the supply of gas in the event of establishment of abnormal conditions in the system.

Another object of this invention is to provide a burner control system of the character described and wherein supply of gas to the burner is normally eflected by a thermoelectrically energized valve, but only when opening of that valve is permitted by means energized by external electric power, or, in the event of failure of that power, by manually operable means.

Another object is to provide a novel control device or valve having particular utility in a burner control system of the character described, but susceptible of other uses.

For full understanding of this invention, and further appreciation of its objects and advantages, reference is to be had to the following detailed description and accompanying drawing, and to the appended claim.

The single figure of the drawing is a schematic view of a gas-burner control system embodying principles of the invention.

In the drawing the numeral 11 indicates a conduit for supplying fuel gas from a conventional source (not indicated) to a main burner 12. In the conduit ahead of the main burner is a gas-pressure operated valve 13. 'This valve comprises a closure member 14 carried by a flexible 2,753,931 Patented July 10, 1956 diaphragm 15 and cooperating with a valve seat provided around a port 16 through a fixed partition separating the inlet and outlet of the valve.

The diaphragm 15 forms a movable partition separating the interior of the lower section 17 of the valve from a pressure chamber 18 above the diaphragm and defined by'the upper section 19 of the valve. Communication between chamber 18 and the inlet of the valve is provided by a pipe 20, and between the chamber and the atmosphere by a vent pipe 21. The ends of pipes 20 and 21 within the chamber are formed to provide valve jets 22 and 23, respectively, between which a cooperating bladelike closure 24 is disposed. This closure is of magnetic material and is fulcrumed on the end of the lower sidearm of a U-shaped electromagnet core 25 around whose upper side-arm is an energizing coil 26. The armatureclosure 24 is biased by a spring 27 into engagement with jet 23.

The electromagnet coil 26 is connected by a pair of Wires 28 to a thermoelectric generating device 29 which is normally continuously heated by combustion of gas supplied to the device through a pipe 30 connected to conduit 11 ahead of valve 13; the gas from pipe 30 also being supplied to a pilot burner 31 whence it issues as a flame 32 for igniting gas at the main burner. The thermoelectric generating device 29 may be the same as disclosed in U. S. Patent No. 2,526,112 and comprises a plurality of thermocouples and an auxiliary burner for heating the same so as to effect generation of electricity in an amount suflicient for operative energization of the electromagnetic operator 24-36; the flames of device 29 and pilot burner 31 being mutually igniting so that deenergization of the operator results if the pilot-burner flame becomes extinguished.

In place of the thermoelectric generating device 29 there may be employed thermoelectric means such as a thermal cut-out heated by the flame of a pilot burner and controlling a local source of electrical energy, such as a storage battery; the thermoelectric means being arranged to effect energization of coil 26 only while the pilot-burner flame exists.

A pair of safety devices or limit switches 33 and 34 are connected in one of wires 28 in series with each other and with device 29 and coil 26. These switches are shown mounted on a structure 35, above the main burner, for heating a medium such as water or air for circulation through a space or room to be heated. The switches 33-34, which are normally closed, may be arranged to respond to a condition resulting from the operation of the burner, such as temperature, steam pressure or boilerwater level, and to open the circuit of coil 26 in the event of establishment of an abnormal degree of the condition.

Inasmuch as the thermoelectric generating device 29 is normally continuously heated, and the electromagnet coil 26 therefore normally energized, there is electromagnetic force normally urging armature-closure 24 to rock clockwise out of engagement with jet 23 and into engagement with the other jet 22. This electromagnetic force is superior to the opposing force of bias spring 27, but, with the parts in the positions shown in the drawing, such movement of closure 24 is prevented by a lever 36 pivoted at 37 and arranged to apply to closure 24 gravitational force superior to and opposing the electromagnetic force acting on this closure. Jet 23 thus being closed, the pressure of the fluid at the inlet of the valve, applied by way of pipe 20 and open jet 22 to chamber 18 and to the top surface of diaphragm 15, balances the pressure of the fluid below the diaphragm so that the main closure member 14 remains seated by gravity.

The lever 36 extends outwardly of chamber 18 through an opening in the side wall of" the chamber '(a'bell'ows device 38 being provided around the lever to seal this opening) and there connected to the plunger 39 of a solenoid operator 40 comprising an energizing coil 41 connected by wires 42 to the secondary of a step-down transformer 43 whose primary is connected to a source of external: electricpower" supplied by a service company and indicated by the A. C- symbol. One of the wires 42. is broken to insertthe leads of a conventional thermostat 44 located in the space heated by the medium supplied thereto from the furnace structure 35'.

When, in. response to demand for heat, the thermostat 44 closes; the solenoidoperator 4% is energized and the lever'36 rocked clockwise so that its portion within chamber 18 is. moved out of the path of. movement of the armature-closure 24, permitting clockwise rocking of: the same under the force exertedby the thermoelectrically energized. electromagnet 25-26 to efifect closing of jet 22 and opening of: jet 23. When this occurs the gas compressed in chamber 18 escapes to atmosphere through pipe 21 (this pipe being extended adjacent the pilot-burner assembly for ignition of the vented gas) so that the diaphragm is raised by the pressure of the gas below itand the main closure member 14 unseated so that gas passes to the main burner where it is ignited by the pilot-burner flame.

When the heating requirement of the space is satisfied and the thermostat consequently opens, the additional electromagnetic operator 49 is deenergized so that the resultant release of lever 36 effects counterclockwise rocking of closure 24 (against the thermoelectrically produced force urging it in the opposite direction) into engagement with. jet 23 so that with the resultant rise of fluid pressure in chamber 18 the main valve is reclosed.

Means are provided for manually operating the lever 36 to raised position in the event of failure of the external electric power. These means comprise a cam 45 pivotallymount'ed at its center and provided with a handle 46 which normally rests on a stop-pin 47. To manually operate the lever 36, and thereby normally effect opening of the main closure member 14, the handle 46 is raised so that the left. lobe of cam 45 engages the outer end of the lever and rocks it to a position wherein the inner. end of the lever is out of the path of movement of closure 24 so that thermoelectric operation of the same to its alternate position is permitted, and opening of the main valve normally effected; the extent of this movement of. handle 46 being limited by another stoppin 48. During the manual rocking of lever 36 the right lobe of cam 45 engages and rocks to closed position: a normally-open switching means 49 connected in parallel with the thermostat 44 so that the circuit of coil 41 is then completed independently of the thermostat: The. handle 46 is maintained in raised position by friction between the cam and the parts engaged thereby.

Before placing the burner in operation manually, precautions obviously should be taken to avoid trouble which might result from operation of the burner in the absence of the external electric power. However, in the event that an abnormal condition does develop in the system, one or both of the limit switches 33-34 will operate to openthe energizing circuit of electromagnet 25-26 so that closure'24 will move to its spring-biased position and effect shut-off of gas to the main burner.

Upon resumption of supply of external electric power the solenoidplunger is magnetically raised to a slightly greater extent, permitting the handle and cam to return by'gravity to normal position. The resultant opening of theswitching means149 theneffects deenergization of the solenoid operator, unless the thermostat is then in heatdemanding condition; operation of the system again being under the control of the thermostat, as well as that of the safety devices 33:-34, and the safety means inherent in the thermoelectric generator whereby shut-'ofi" of gas to the main burner is efiected if the pi1ot-burner flame is extinguished.

For the purpose of this invention a simple vent valve may be substituted for the three-way pilot or auxiliary valve constituted by jets 2223 and closure 24; a port for bleed of pressure gas into chamber 18 then being provided, as is well known in the art. Moreover, in place of the fluid pressure operated valve 13 there may be employed a main-burner supply valve operated directly by the small amount of energy produced by the thermoelectric generator; a valve of that character being disclosed in my Patent No. 2,358,828.

Still further modification of the system herein disclosed may be made without departing from the spirit of the invention, and I intend therefore to be limited only by the scope of the appended claim.

I claim as my invention:

In a gas-burner control system: a main burner; a gassupply conduit leading to said main burner; a valve in said conduit for controlling supply of gas to said main burner and biased to closed position; a pilot burner for igniting said main burner and connected to said conduit ahead of said valve; a first electromagnetic device adapted, while energized, to efiect' application of force to said valvein a sense to open it; means for normally continuously energizing said first electromagnetic device comprising a thermocouple device electrically connected thereto and subjected to the flame of said pilot burner; a second electromagnetic device for controlling the operation of said first electromagnetic device and thereby the operation of said valve, said second electromagnetic device being so biased and arranged that, when uneuergized, it applies force to said first electromagnetic device superior to and opposing the force produced in the same by current from saidthermocouple device so that said valve is then closed under the force of its bias, and, when energized, to permit electric operation of said first electromagnetic device so that opening of said valve is then normally effected; an external source of electric power for energizing said second electromagnetic device; a thermostat controlling the energization of said second electromagnetic device and thereby normally the operation of said valve; mechanical means for manually operating said second electromagnetic device to energized position in the event of failure of said external electric power so that said electric operation of said first electromagnetic device is then permitted in the absence of the external electric power; said mechanical means including switching means arranged to complete the energizing circuit of said second electromagnetic device, independently of said thermostat, when the second electromagnetic device is manually operated to said energized position; means, effective only while said second electromagnetic device is uneuergized, for maintaining said mechanical means and the second electromagnetic device in manually operated position; and safety means responsive to a condition resulting from the operation of said'burner for eitecting deenergization of said first electromagnetic device, and thereby closing of said valve, in the event of establishment of an abnormal degree of said condition.

References Cited in the file of this patent UNITED STATES PATENTS Re222 ,76( Peterson May 28, 1946 2,288,890 Denison July 7, 1942 2,294,693 Ray Sept. 1, 1942 2,457,378 Johnson Dec. 28, 1948 2,505,432 Sugar Apr. 25, 1950 2,517,363 Thornbery Aug. 1, 1950 FOREIGN PATENTS 531,301 Great Britain Jan. 1, 1941

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