US2365102A - Pilot fob gas burners - Google Patents

Description

9 A. D. oLns 2,365,102

I PILOT FOR (111s BURNERS' Filed'llay 5, 1941 z Sheets-Sheet 1 INVENTOR flmbrase D O/d ATTORNEY Dw 1944- A. D. OLDS 2,365,102

- PILOT FOR GAS BURNERS Filed May 5, 1941 2 Sheet s-S heet 2 INVENTOR gmbrose 0. 0/ds.

A'rroiaNEY Patented Dec. 12, 1944 PKLOT FOR GAS BURNERS Ambrose D. Olds, Wichita, Kans., assignor to The Coleman Lamp and Stove Company, Wichita, Kans., a corporation of Kansas Application May 5, 1941, Serial No. 391,977 4 Claims. (Cl. 158-H7JL) This invention relates to a safety pilot apparatus for maintaining a fluid fuel supply to a-burner when the pilot flame is in operation and adapted for suspension of the fuel supply when the pilot flame is extinguished.

The principal object of the invention is to provide aself-seating control valve closed responsive to pressure of the fuel supplemented by spring pressure but which is maintained open by. action of a thermostat energized by small-jets of flame established by the pilot flame.

it is also an object of the invention to provide for heating the thermostat indirectly by heat conducted and radiated from a. protecting member or shield which is directly heated from the small jets of flame to thereby provide a more sensitive and longer life thermostat since it is maintained at lower temperature.

Further objects of the invention are to provide a pivotal mounting for the thermostat so that it is free of internal stresses other.than that effected by temperature; to provide a floating connection-between the thermostat and the valve actuated thereby; to provide a readily manipulated thermostat adjustment; and to provide for locating the thermostat in the stream of cool air being supplied to the heater so that. it will cool faster when the pilot flame is extinguished.

in accomplishing these and other objects of the invention, as hereinafter described, I have provided improved details of structure, the preferred form of which is illustrated in the accom- Denyin drawings, wherein:

Fig. l is a perspective view of a floor furnace equipped'with the present invention, parts of the furnace walls being broken away to show the,

and flame ladder shown in disassembled spacedrelation.

Referring more in detail to the drawings:

i designates a heating appliance such as a floor furnace equipped with a, main burner 2 which, in the illustrated instance, includes an elongated manifold 3 carrying a plurality of burner jets 4, each of which includes a slotted. burner head 5 supplied with a combustible fuel mixture through a venturi 6 in which primary air passing between the arms of the jet support i is mixed with a gas emitted from the manifold chamber .3 through orifice tips 9. Fuel is admitted to the manifold through a lateral connection ill from a supply pipe ll under control of a room thermostat (not shown) and a marin ally actuated valve l2.

The burner thus described is connected with the bottom of a, heater unit I3, through which hot products of combustion are circulated and discharged through an outlet M to a suitable vent responsive to draft or pressure differential between the interior and exterior of the heater unit so that a constant supply of fresh combustion supporting air is moved upwardly around the manifold of the burner to maintain combustion of the fuel.

Connected with the fuel supply pipe ahead of the valve I2 is a, pipe l5 for supplying fuel to a pilot burner including a Bunsen tube 16 when a manually operated stop valve H is opened. The Bunsen tube is best illustrated in Fig. 8 and includes a tube-like body l8 having a mixing chamber supplied with combustion supporting air through inlets l9 which are provided in a .head 20. The head 20 hasa, threaded neck 2! which is connected by a union nut 22 with the pilot supply pipe l5. The elongated body I8 has a swedge-shaped discharge end 23 and a plurality of lateral orifices 24' for emitting small portions of the fuel mixture which are lighted the Bunsen tube is a larger opening 25 through which fuel is discharged for the main pilotflame and which is connected with the zone of the and floating stem connection between the ther-;

mostat and the ball or the valve. Fifi? 5 is a cross-section on the line 5-5 of v Fig. 6 is a partial cross-section on the line 6-6 of Fig. 3.

Fig. 7 is a detail perspective view of the thercostat. v

Fig. 8 is a perspective view of the pilot bimsen joriflces 24 by a slit 26. The Bunsen tube thus center of the main burner. The Bunsen is anchored in the opening?! by a set-screw 29 which is threaded into the boss and has its shank engaging in a socket 30 of the Bunsen to prelower end to pass the reduced end of the Bunsen.

The flame ladder is anchored to the Bunsen by a screw 34 extending through an opening 35 in the opposite side of the ladder tube and into a threaded socket 338 formed in the end of the Bunsen. The flame ladder is supported so that the upper end is adjacent one of the burner heads 5 and is stabilized by a bracket arm 37.

With the construction thus far described, fluid fuel is admitted to the Bunsen of the pilot and a combustible mixture is discharged through the opening 25, which, when lighted, results in a flame playing along the open slot of the ladder to the top thereof for igniting the fuel mixture delivered to the burner whenever the room rheostat calls for heat. When sufllcient heat is supplied to the room, the room thermostat functions to shut off the gas supply to the burner, however,

the pilot burner will remain ignited to relight the burner when the thermostat again opens the fuel supply to the burner. There is a chance, however, that the pilot light may become extinguished with the result that Whenthe fuel supply to the burner is turned on and there is no flame to effect i nition, the combustion chamber will fill with a highly explosive mixture. In order to avoid this possibility the pilot is provided with a thermostatically operated safety valve to automatically shut off the fuel supply when the pilot flame is extinguished and which is now to be described.

The safety valve 38 is mounted in the connection l0 and includes a bushing-like body 39 threaded into a counterbore 40 of the fuel inlet opening 4| of the connection Hi. The bushing is inserted from the opposite side of the manifold through an opening 42' which is closed by a threaded plug 44' after the valve has been inserted. Formed in the discharge end of the bushing is a port 45 having an annular valve seat 46 to seat a ball type. valve ll in the directiOn offiow of the fuel to the manifold. The

ball valve is normally retained on the seat to shut off flow of fuel by the pressure of the incoming gas supplemented by a coil spring 48 which is seated against a ring 49 engaged between the bottom of the counterbore and the valve body as shown in Fig. 4.

In order to open the valve" responsive to operation of the pilot, the burner is provided with a thermostat unit assembly 50 which is best illustrated in Fig. 7. The thermostat unit includes a bimetal thermostat blade 5|, having one end secured within a channel-like saddle 52 by a fastening device, such as a rivet 53. The fixed end of the bimetal thermostat blade is closely embraced by the'web 54 and flanges 55 and 5B of the channel-like member so that it forms a rigid part thereof. The opposite end of the saddlelike member has an opening 51 therethrough to pass the threaded shank 58 of an adjusting screw having a slotted head 59 adapted to be rotated by a screw driver or the like when adjusting the thermostat as later described. Threaded on the shank of the screw is a sleeve 50 spaced from anchored to the saddle member but is rotatable therein. 1

The flanges 55 and 55 of the channel member have ears 53 and 64 engaging over an extension 55 of the lug 28 and which are pivotally connected therewith. by a cotter pin or like. fastening device 58 extending through openings 61 in the ears and through an aligning opening in the lug after the terminal end of the screw has been threaded into a threaded socket 658 of the lug 28. When the thermostat unit is thus applied, the thermostat blade projects over the plug 44 and would ordinarily be in position to be contacted by the jets of the pilot flame from the orifices 24. However, in accordance with the present in vention the bimetal thermostat blade is energized responsive to conducted and radiated heat and not by the direct contact of the pilot flame.

.The thermostat blade is protected by means of a shield 59 in the form of an angl and having a leg 10 projecting upwardly between the jets of flame and the thermostat and a substantially horizontal leg H extending under the lower edge of the thermostat blade, as clearly shown in Fig. 7. The end of the shield adjacent the saddle is fixed to the thermostat blade by a fastening device, such as a rivet I2, which extends through an opening in the thermostat blade, through a washer l3, and ,through a registering opening in the leg Hl of the shield. The opposite end of the shield is bent away from the thermostat blade to allow independent movement of the free end of the thermostat blade responsive .to heat of the jets of flame which are conducted by way of the rivet connection l2 and by heat radiated from the surfaces of the angle.

In order to provide a floating connection between the free end of the thermostat blade and the ball of the valve, the plug 44 is provided with an axial bore 14 for slidably supporting a rodlikestem or shaft 15 having its inner end 15 freely engaging the ball and its outer end H in position to be engaged by the free end of the bimetal thermostat blade so that when the thermostat warps responsive to heat from the pilot, the stem is pushed thereby through the bore of the plug to unseat the valve and open the manifold to the supply of fuel.

In operation of the apparatus ,thus described,

the thermostat blade is adjusted relatively to the end ll of the stem 15 by rotating the screw 58 in the threaded socket 68 of the lug 28 so as to pivot the saddle member 52 on its support for moving the outer end of the thermostat blade 5| in desired relation relatively to the end- 11 of the stem 15 when the burner is cold and prior to lighting of the pilot burner flame. The pilot burner is then lighted. This is effected by opening the valve I! so that gas is delivered through the pipe l5 into the Bunsen tube l8 to mix with air admitted through the openings I9 in forming a combustible mixture which is discharged through the opening 25 and orifices 24. The mixture is lighted by applying a flame to any one of the jets which will effect ignition of the other of flame are playing on the shield 89, which heat is initially conducted through the rivet 12 to quickly heat the thermostatblade and cause energization or warping thereof in the direction of the stem 15. As the thermostat receives additional heat through the heat radiated fr m the fuel supply to the burner.

legs 10 and H of the shield 69, the thermostat blade effects opening of the ball valve 41 to allow inlet of gas to the burner manifold chamber 8, which is mixed with the primary air and discharged as a combustible mixture through the slotted heads 5, which mixture is ignited by the pilot flame.

When the heater has been in operation a sufficient time to raise the room temperature to that set by the room thermostat, the thermostat valve (not shown) will function to suspend the However, the pilot flame will remain lighted to again light the burner jets when the room thermostat calls for additional heat. Should the pilot flame become extinguished, the thermostat blade will cool off and allow the gas pressure in the supply pipe, supplemented by action of the-spring 48, to close the ball valve 41 and prevent flow of gas into the burner chamber 8 even though the thermostatically operated valve (not shown) should function. The safety valve thus prevents gas from entering the burner and escaping into the com-' bustion chamber unless the pilot light is' in operation. The safety valve 41 is automatically opened whenever the pilot light has been relighted and the thermostat blade has accumulated sufficient heat to actuate the stem I5.

From the foregoing it is obvious that I have provided a safety pilot which is positive in operation and the thermostat blade is adapted for operation over longer period without taking on a permanent set for the reason that it operates under relatively low temperatures.

Attention is also directed to the fact that'the thermostat element is located in the path of the relatively cool combustion supporting air and out of the heating influence of the burner heads 5, thereby assuring a more sensitive and positive acting thermostat. The floating connection between the thermostat and the ball valve compensates for any misalignment, consequently there is nothing to bind and prevent operation of the safety valve responsive to the thermostat. The pivotal mounting of the thermostat by means of the saddle member also relieves the thermostat of any internal stresses other than those effected responsive to heat of the pilot. The saddle member is also readily manipulated to position the thermostat 5| relatively to the projecting end 13 of the floating stem I5 which effects unseating of the safety valve ball 41.

What I claim and desire to secure by Letters Patent is:

1. In combination with a main burner for fluid fuels; a self-seating valve for shutting ofl flow of fuel to the main burner, a stem for unseating the valve, a pilot burner for lighting the main burner, a bimetal thermostat blade having one end registering with the stem of said valve, means for supporting the other end of the thermostat blade in fixed position relatively to the valve, and a shield on a side of the thermostat blade facing the pilot burner and having one endflxed to the thermostat blade at a point spaced from the means supporting the thermostat blade for providing a point of heat conduction between the shield and thermostat blade. said shield being spaced from the thermostat blade to limit transmission of conducted heat from the pilot flame to the thermostat blade to said point of heat conduction'.

2. In combination with a main burner for fluid fuels, a self-seating valve for shutting off flow of fuel to the main burner, a stem for unseating the valve, a pilot burner for lighting the main burner, a bimetal thermostat blade having a free end registering with the stem of said valve, a saddle member fixed to one end of the bimetal thermostat blade, pivotal mount ng means for the saddle to support the thermostat blade relatively to the valve, a shield carried by the thermo-' stat blade and spaced from a side of the thermostat blade facing the pilot burner, means for attaching the shield to the thermostat blade in spaced relation therewith for providing a point of heat conduction between the shield and thermostat blade, and an adjusting screw carried by the saddle member and having threaded engagement with a part of the burner for rocking the saddle member to adjustably position the free end of said thermostat blade to and from the valve stem.

3. In comb nation with a main burner for fluid fuels, a valve for shutting off fuel to the main burner, an operating stern for opening the valve, a pilot burner for lighting the main burner, a bimetal thermostat blade positioned laterally of the pilot burner, means for pivotally supporting one end of the thermostat blade with the other end of said thermostat blade registering with the actuating stem of said valve and adapted to open the valve when energized by heat of the pilot burner, a shield between the pilot burner and the thermostat blade for protecting the thermostat blade from direct contact by the-flame of said pilot burner, and means spaced from said pivotal supportingmeans for mounting the shield on the thermostat blade and forming a point of heat conduction to the thermostat blade.

4; A pilot control for a main burner for fluid fuels including a pilot burner for furnishing a flame to ignite fuel when discharged from the main burner, a support associated With the pilot burner, a saddle member, means for pivoting the saddle member for rocking movement on the support, a thermostat blade fixed to the saddle member on oneside of the pivotal support, a self-closing valve for shutting off fuel to the main burner, an actuating stem arranged to open the valve, said thermostat blade being arranged the thermostat blade with the shield spaced from the thermostat blade for providing an air passage- .way therebetween, said attaching means providing a heat conductive connection between the shield and thermostat blade for conducting heat from the pilot flame to the thermostat blade to energize the thermostat for actuating the .valve stem to open the valve.

, AMBROSE D. OLDS.

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