US2582419A - Sheetsxsheet i - Google Patents

Description

Jan. 15, 1952 E. J. DILLMAN ETAL GAS BURNER CONTROLLING MEANS Filed April 20, 1945 2 SHEETS-SHEET 1 I867 55 a i FlG.2 34

M ATTORNEY 1952 E. J. DILLMAN ET AL 2,582,419

GAS BURNER CONTROLLING MEANS Filed April 20, 1945 2 SHEETS'SHEET 2 751M ATTO RNEY Patentedlm'is, 1952 UNITED STATES PATENT OFFICE 2,582,419 GAS BURNER OONTROLLINQ MEANS Earnest J. Dilhnan moi, assignors 14 Claims.

The invention relates generally to automatically operated valve means for controlling the flow of fluid, and it has particular relation to the control and burning of fuel in a heating system.

One object of the invention is to provide an improved automatically operating valve which is actuated in predetermined relation to a pilot valve.

Another object of the invention is to provide as an article of manufacture, an improved valve arrangement for controlling the flow of fuel and which includes a main valve control and a pilot valve control arranged in a compact structure readily connectable to a fuel supp line.

Another object of the invention is to provide an improved valve arrangement for controlling the flow of fuel and for igniting the same through the use of electrical ignition.

Other objects of the invention will become apparent from the following specification, from the drawings relating thereto, and from the claims hereinafter set forth.

For a better understanding of the invention, reference may be had to the drawings wherein;

Figure l is a view, generally diagrammatical, illustrating an arrangement constructed according to one form of the invention for controlling the flow and burning of fuel in a fuel burning apparatus;

Fig. 2 is a vertical section of a valve arrangement forming part of the invention as seen substantially along the line 22 of Fig. 3;

Fig. 3 is a cross-sectional view taken substantially along the line 3-3 of Fig. 2;

. Fig. 4 is a cross-sectional view taken substantially along the line H of Fig. 2;

Fig. 5 is a cross-sectional view taken substantially along the line 5-5 of Fig. 4;

Fig. 6 is a cross-sectional view taken substan-' tially along the line 66 of Fig. 4;

Fig. 7 is a detail view of the lower part of the pilot valve showing the seat, inlet and outlet; and.

Fig. 8 is a cross-sectional view taken substantially along the line 88 of Fig. '7.

Referring to Fig.1, the general features of the present invention will be more readily understood through reference first to different parts of the arrangement and briefly setting forth the manner in which such parts function and co-operate. In the first place, gaseous fuel is supplied through a main line connected to an inlet 9 of a main valve Ill, and from this valve the gas flows through a line H to a main burner i2. The main valve includes a separating wall ll having an inlet or ,valve opening ll which is adapted and Jack E. Fleur-y, Detroit, to Detroit Lubricator Company, Detroit, Mich a eo 'lwration of Michigan Application April 20, 1945, Serial N0. 589,414

2 to be closed or opened by a valve member it. The main burner is adapted to be ignited by a pilot II which is at the end of a fuel line it, and the supply of fuel to this pilot is controlled by a pilot valve indicated diagrammatically at it.

Ignition of the pilot is effected by electrical igniting means indicated at 20 which is in the secondary circuit 2i of a transformer 22. The primary in this transformer indicated at 23 is shown in the circuit of a room thermostat 24, and for the purposes of simplicity, both the primary 2! and thermostat 24 are shown as connected to ordinary house circuit lines indicated by wires 28 and 2. The primary 22 and thermostat 24 are also in series circuit with the primary 28 of a transformer 28 shown as adjacent the pilot valve It. The secondary II of the transformer 29 is in the circuit of a heat motor 3| which acts to control the pilot valve as hereafter will be considered in greater detail.

Prior to describing parts of the valve controlling device, it might be mentioned briefly that when the thermostat 2i closes so as to require heat, thecircuit is closed through the electrical ignition 20 and sparking occurs across the ignition points as will be readily understood. At the same time, the pilot valve I! will open to allow flow of gas to the pilot l1, and as a result, the pilot II is lighted. As the pilot heats up, a bulb element 32 attached to the side of the pilot, automatically effects operation of a bellows device 23 to open the main valve ill, and as a result gas flows to the main burner 12 and is ignited by the pilot. Operation of the main burner continues until thermostat 24 opens the circuit through the primary 28. As soon as the circuit through the primary motor ll cools, the pilot valve closes, the pilot l1 cools, and in turn the main burner valve Ill closes. This brief description is merely intended to provide initial understanding of the invention in a general way so that a detailed description of the valve arrangement in the succeeding figures will be perhaps better understood as the description proceeds.

Now referring to Fig. 2 in particular, the main valve ll including the valve element 15 embodies the same structural features as are embodied in the copending application of Earnest J. Dillman, Serial No. 445,571, filed June 3, 1942, now Patent 2,409,112, and therefore, it would seem needless to refer to this structure in full detail. Briefly, however, it may be stated that the valve seating element includes a stem 34 which is reciprocatory in a vertical direction through an 28 is opened, the heatv upper cover part 35 of the valve casing, which is secured thereto. A flexible diaphragm 35' is sealed to the stem 35 and to the casing to prevent leakage of gas. The upper end of the stem is slidably mounted in a collar 38 anchored in a frame 31 projecting upwardly from the cover 35,- and below the collar the stem 34 passes through and is fastened to a sleeve 38 having disk portions 39 and 40 integral or rigid with its ends. The lower disk portion 40 serves as an armature which is immediately above a stationary permanent magnet 42 having an opening at its center allowing the valve stem to move therethrough. The magnet normally acts to hold the armature 44 in its lower position and to hold the main valve closed.

At one side or the post 31. a control device 43 including a bracket 44 is pivotally anchored on the cover 35 as indicated at 45, and this bracket carries an arm 45 having a roller 41 disposed between the two flange or disk portions 39 and 40 on the sleeve 38. Upward movement of the arm 46 is opposed by a spring 41*. The construction of the parts to which reference has thus far been made, is the same as the construction disclosed in the said copending application for patent, Serial No. 445,571, filed June 3, 1942, now patent 2,409,112, and it would seem needless to describe all the details here. It would seem suillcient to say it external means (presently to be described) is provided to move the sleeve 38 upwardly against the action of the magnet 42, that as soon as the moving force becomes suflicient, the valve will quickly and partly open against the magnetic force and the lower disk portion will then strike the roller 41 and slowly move the arm 46 upward against the force of spring 41 thereby continuing the opening movement of the valve member 15.

The valve structure so far described extends upwardly into a housing or casing 50 which includes two laterally disposed parts and 52 having, as best shown by Figs. 2, 3, and 4, base portions 53 and 54. An opening 55 in the base portion 53 allows the valve structure described to project upwardly into the casing, and the valve cover 35 is secured to such base portion by screws.

55. The base portion 54 is disposed on the base portion 53 and is releasably secured thereto and to the cover 35 by means of oppositely disposed bolts 51 which are threaded into the cover. These bolts extend through open ended notches 58 and 59 in the end of the base portion 54 so as to permit ready separation of these two parts of the casing. Also, for accommodating the valve structure, the base portion 54 has a recess or opening 60 corresponding to a part of the opening 55 in the base portion 53.

At their opposed ends, the two parts 5| and 52 of the casing have upright end walls 54 and 55, and along the edges of the base portion 53, upwardly directed short flanges 65 and 61 are provided. The casing is completed by means of a U-shaped closure or cover 68 which has side walls extending downwardly so as to complete the sides of the casing and short downwardly directed end flanges 59 and which are fastened to the upright walls 64 and 55 by screws ll. From this it follows that a readily separable casing is provided for housing the valvestructure.

The external means mentioned for opening the valve comprises, as best shown by Figs. 1, 2, and 3. a plate type lever or arm I2 which is fulcrumed on a pin 13 extending through ears 14 and on the lever. In turn, the pin is supported at its ends in legs 18 and 19 of a bracket 80 secured to the wall 55 part 52 0:" the casing by screws 88 passing through the base of the bracket. Tongues and 82 are provided on leg 19 and rest on the base portion 54 of the casing, and rivets 33 provided on the tongues have locating relation to openings 84 in such base portions as seen in Fig. 4. The lever '12 at its inner end. 85 extends between the disk portions 39 and 40 on sleeve 38 so that if the lever is swung vertically it will shift the sleeve and move the valve stem 34. It will be noted that the inner end of the lever has a downwardly turned lip 85 so that if the valve member l5 sticks in open position when the lever starts to move downwardly, it will almost immediately contact the armature 40 and force the valve member to closed position.

Movement of the lever 12" about its fulcrum is effected by means of the bellows device 33 which includes a casing 85 secured to the wall 65 by the screws BI and a bellows 89 within the easing which is fastened to a thrust member or pin 90. This pin extends through openings in the wall 52 and bracket Ill. and has a conical end 9! which seats in a conical seat 92 formed in a depending leg 93 on the lever I2. Collapsing of the bellows moves the lever 12 in a clockwise direction as seen in Fig. 1, so as to cheat opening of the main valve while return movement of the bellows allows the valve to close. This return movement is effected by means of a spring 94 within the casing 88 which is disposed around pin 90.

The bulb 32 previously mentioned, is connected by a tube 95 and coupling 86 to the casing 88, and the casing externally of the bellows as well as the tube 95 and bulb 32 contains a volatile fluid so that upon heating of the fluid in bulb 32, the bellows will collapse and then upon cooling of the fluid the bellows will expand through action of the spring. The rear of the bellows may be open to atmosphere along the end of pin so a: to allow air to escape and enter as will be readily understood. From this, it should be evident that if the pilot light I! is ignited, the bulb 32 will become heated and as a result, the main valve will open. It will also be evident that as the pressure against the lever eifected by the bellows device increases, it finally overcomes\the magnetic force acting to hold the valve closed, until a substantial force is built up and which is sufficient to overcome the magnetic force. As soon as this magnetic force is overcome, the valve member I5 is quickly and forcefully opened so as to allow a partial supply of gas to the main burner l2 which will then ignite since the pilot I! is burning. Continued heating of the bulb 32 will move the valve member 15 to wide open position.

Now directing attention to Figs. 2 and 4 in particular, the pilot valve indicated at 19 in general comprises a bottom part III] disposed within the casing and fastened to the bottom parts thereof 5 by means of screws III. A central projection I02 on this base portion of the valve is disposed in openings in the two parts SI and 52 of the casing mentioned so as to accurately locate the valve. As best shown by Figs. 4, 7, and 8, this bottom part of the valve has an inlet I03 connected by a threaded coupling 104 to a fuel supply line N15 to the pilot H. Also this part of the valve has an outlet .105 connected by a threaded coupling I01 to the line I! previously identified. It may be observed that the coupling I04 extends through an opening in the end wall 55 while coupling I01 extends inwardly above the side flange 51. At its inner end the inlet opening 12 communicates as indicated at I52 with a recess H5 in the upper side of the valve base I55, and this recess at its lower end has a smaller opening or valve port III which as best shown by Fig. 5. communicates with an opening I'I2 leading to the outlet I55.

The upper part of the valve is indicated at III and is fastened to the base portion I55 by screws indicated at II5. These two parts of the valve hold a rubber diaphragm II1 over the recess H5, and the diaphragm is sealed at its center to a valve stem II5 which has a lower conical end II5 to meter the now of gas to the pilot I1 and which is adapted to close the upper end of the opening III and thereby interrupt the flow of gas. If the diaphragm and stem are moved upwardly, the gas flows beneath the diaphragm and downwardly through the opening III and then through the opening II2 to the outlet line II.

The valve stem is slldably mounted in a guide element I2I threaded into the upper part III of the valve as indicated at I22. This guide terminates at its upper end in a surrounding flange which is a permanent magnet I2I adjustably locked in position by means of a set screw I22 threaded through said upper part I I5 oi the valve. Above the magnet I2I a collar I which is the armature cooperable with magnet I2I'. is rigidly connected to the valve stem III by means of a pin I25, and this collar has upper and lower flange or disk portions I25 and I21. Movement of this collar upwardly and downwardly carries the valve stem I I5 with it and thus will open and close the pilot valve. The upper part II5 of the valve has at its upper side a generally rectangular extension I25 which is interlorly hollow so as to provide a space for the magnet HI and armature I25. The valve stem II5 after extending through this hollow or space is slldably mounted at its upper end in a bushing I2I, This bushing is threaded downwardly into the upper wall of the extension I25 and a lock nut I22 on the bushing serves to hold it in any adjusted position.

Referring to Figs. 4 and 5, the heat motor 2I comprises a bimetal strip I55 having one end projecting between the two disk portions I25 and I21 on the collar I25 and engaging the underside of the upper portion I25. This end of the strip has a downwardly turned leg I adapted to engage the lower disk portion I21 to close the pilot valve I9 if it should stick In open position. The heat motor also includes a strip of electric insulating material I52 disposed on the strip I55 in superimposed relation thereto, a strip of mica I52 disposed on the strip I52. and an upper strip of electric insulating material I55. This assembly is held in laminated relation at one end by a tongue I55 struck from the strip I55 which is bent over In embracing relation to the ends of the other strips.

All four strips are anchored at their other ends on a block of insulating material I55 by means of bolts I55 and III extending through the several strips and through the block. The latter has trunnions I52 and I52 at opposite sides which fulcrum in notches I55 and I55 formed in opposite legs I51 and I55 projecting upwardly from a metal strip or supporting member I55. This strip I55 has an opening I5I receiving the upper part I I5 of the valve I5, and it is fastened to that part of the valve by means of the screws H5.

The bolts I55 and I5I also extend through a bimetal compensating strip I55 disposed at the bottom side of the block I55 and nuts I55 on the lower ends of the bolts hold the parts securely in position. For the purpose of releasabiy retaining the trunnions I52 and I52 in the notches provided therefor, a U-shaped clip I55 embraces the strip I55 and the legs I51 and I55, and upper ends of the clip have inwardly turned lips I55 and I55 which snap over the upper sides of the trunnions. The clip may have additional lips such as indicated at I15 embracing side edges of the legs I51 and I55 so as to properly locate and hold the clip in position.

At its outer or free end the compensating strip I55 is provided with a notch I12 which is engaged by a T-shaped upper end I12 formed on a bracket element I15 anchored on the strip I55 by means of rivets I15. A screw I15 freely extending upwardly through the strip I55 is threaded into the bracket I15, and from this it follows that by adjusting the screw, the strip I55 may be shifted upwardly or downwardly. This adjustment corresponds to adjustment of the strip 52 in the said copending application for patent and is employed to vary the time period required to move the pilot valve to open position. The compensating strip I55 when heated acts to rotate the supporting block I55 to relieve the tension of the heat motor 2I holding the valve I5 open, so that on deenergization of the heat motor the cooling time for closure of the pilot valve will be reduced. The strip I55 is heated by increase of ambient temperature when the heat motor H is energized and also by some conduction of heat through the bolts I55 and I5I from the heat motor.

The strip of mica I52 has a heating coil I55 wound about it, and the ends of the coil are electrically connected to the two bolts I55 and III which are electrically insulated in any suitable manner from the bimetal strips I55 and I55. The lower ends of the bolts, as best shown by Fig. 5, are connected to wires III and I52, and these wires are connected to terminals I52 and I55 on an insulating plate I55 secured by screws I25 to the base portion 52 of the casing. In turn, the terminals I52 and I55 are connected to wires I51 and I55 extending through an opening in the casing, and which are connected to the secondary 25 of the transformer 25.

Now directing attention to Figs. 1 and 2, the inner end 55 of the lever 12 has a link I55 pivotally connected thereto as indicated at I55. This link is pivotally connected as indicated at Hi to a lever or arm I52 having depending ears I52 pivoted as indicated at I55 on an arm I55 projecting upwardly from the portion I25 of the valve I5. The arm I52 at the opposite side of the pivot I55 is reve'rsely bent at its outer end as indicated at I55, and this reverse bend provides a stop for a spring element I51 which is riveted to the arm at a point indicated at I55. This spring element I51 has a nib I55 adapted to engage the upper end of the pilot valve stem H5 and to move it toward closed position to an extent depending upon adjustment of bushing I3I which acts as a stop for engagement by the nib The device functions as follows. When the room requires heat and the thermostat 25 closes. a circuit is completed through the transformer 22 which energizes the heat motor 2I to stress the free end of the upper bimetal element I55 upwardly against the force of the magnet I2I when the force of the element I55 overcomes the magnet I2I, it will bend upwardly and quickly raise the pilot valve stem III to open the pilot valve. Gas is thus supplied to the pilot I1 in sufilcient volume to prevent a flash back. Closing of circuit at the thermostat also closes the circuit of the ignition transformer 22 to energize the electrical ignition 20, and it follows that when the gas reaches the pilot it is ignited. As the pilot heats up, the volatile liquid in the bulb 32 expands, and the pressure exerted through the tube 95 collapses the bellows 89 against the action of the spring 94, and this causes the lever I2 to fulcrum clockwise. As the lever fulcrums, it tends to raise the collar 38 and with it the stem 34 and as soon as the force is sufiicient to overcome the magnet 42, the main valve opens quickly and gas flows to the main burner I2 where it is ignited by the pilot. After the main valve opens, the armature 40 strikes the roller 41 and further upward movement of the valve is restrained temporarily until the force of the spring 41- is overcome. Also, the upward movement of the end 85 of lever 12 causes the arm I92 to move and this causes the spring element I91 to move downward and engage the projecting upward end of the valve stem II8 which is now above the bushing I3I. Thus any tendency of the main valve to open further, creates a force tending to move the pilot valve stem towards closed position. The continued upward movement of lever 12 moves the pilot valve I9 toward closed position and reduces the flame at the pilot IT. The bushing I3I is adjusted for engagement by the spring I91 to prevent full closure of the pilot valve I9 so as to maintain the pilot fiame. The spring I91 provides lost motion so that the lever 12 can have continued main valve opening movement when the pilot valve has been moved by the spring I91 to its minimum open position. The magnet IZI' will not close the pilot valve at this minimum position because of the opposing force of the energized heat motor 3|. It will be evident that any reduction in the pilot also reduces the pressure of the volatile liquid against the bellows and any reduction in this pressure on the bellows tends to allow the main valve to move towards closed position, and this in turn reduces the pressure on the pilot valve, so that the heat motor 3| will move the pilot valve toward open position. valves will float or modulate under the counteracting forces of their respective thermal actuating means until they reach a balanced floating condition with a relatively low pilot flame while the main valve still is fully opened. Variations in this performance can be obtainedby adjusting the device 43, as has been brought out in the said copending application for patent, by adjusting the action of the heat motor through adjustment of the screw I16, and by adjusting the bushing I3 I.

With the main burner now operating and the pilot light also burning with a low flame, the furnace supplies heat until the thermostat 24 is satisfied, and then when the thermostatopens, the circuit through the heat motor is interrupted and this causes the pilot to close and thereafter the bulb 32 cools and finally the main valve closes. The throttling of the pilot valve to provide the minimum flame at the pilot burner which will hold the main valve fully open reduces the cooling time for the bulb 32 when the pilot is extinguished so that the main valve closes more'promptly. The term throttle or throttling as used herein is hereby defined as a reduction in valve opening as distinguished from a complete closing of the valve. The main valve In fact. the two 8. closes sharply, as will be evident from the previous application, after the valve has been moved to the minimum desirable open position where the magnet 42 picks up the armature 40 and snaps the valve closed.

With respect to assembly, it is to be observed that the main valve and parts to the left thereof may be mounted on the casing part El and that the pilot valve and other parts to the right of the main valve may beassembled separately with the casing part 52. Then the two casing parts may be brought together and connected by the bolts 51 and the screws II'II may then be inserted to lock the pilot valve to both parts of the casing.

Although only one form of the invention has been'illustrated and described indetail, it will be apparent to those skilled in the art that various modifications may be made without departing from the scope of the claims.

What is claimed is:

1. An automatic valve assembly comprising a first valve operating stem, a second valve operating stem, a collar fastened on the second stem and having spaced flanges, an electric heat motor having a portion projecting between the flanges, a collar fastened on the first stem and having spaced flanges, a pivoted arm having a portion projecting between the flanges on the collar on said first stem, thermally controlled means for moving the collar on the first stem independently of the second stem, and means on the arm and operatively engageable with the second stem for effecting a closing movement of the second stem upon predetermined valve opening movement of the arm.

2. An automatic valve assembly comprising a first valve operating stem, a second valve operating stem, a pivoted arm, means operatively connecting the arm to the first stem for moving it, an electric heat motor, means operatively connecting it to the second stem for moving it, independently of the first stem and means on the arm and operatively engageable with the second stem for reversing operation of the second stem relative to said heat motor upon predetermined normally biased toward closed position, an electric heat motor for moving said first valve member toward open position, thermostatic means adapted for response to the extent of opening of said first valve member, said thermostatic means including a movable arm engageable with said second valve stem and operable to move said second valve member toward open position, means limiting opening movement of said second valve member, a lever mechanism operatively connected to said arm and engageable with said first valve stem upon predetermined valve opening movement of said arm and operable upon movement of said arm beyond said predetermined movement to move said first valve member toward closed position, means operable to stop cl0sing movement of said first valve member by said lever mechanism at a predetermined minimum opening for said first valve member, and lost motion means operable to permit continued valve opening movementby said arm after said first valve closing movement has been stopped.

4. In a burner control system including a main burner and a pilot burner, a pilot valve having a valve stem, a main valve having a valve stem. each of said valves being normally biased toward closed position, an electric heat motor for moving said pilot valve toward open position, said pilot valve being arranged to supply fluid fuel to said pilot burner, a bellows type thermostat having a bulb element responsive to the heat of said pilot burner, a pivoted arm operated by said thermostat and engageable with said main valve stem to move said main valve to open position, a guide member for said pilot valve stem having a lower face operable as a stop to limit upward movement of said pilot valve, a pivoted lever operatively connected to said arm and engageable with said pilot valve stem upon predetermined opening movement of said main valve by said arm, said lever being operable upon engaging movement to move said pilot valve toward closed position to throttle the flow of fuel, said guide memto a predetermined minimum opening, and said lever having a lost motion spring for transmitting movement to said pilot valve stem and operable to permit overtravel of said lever upon engagement with said guide member so that said main valve may be opened further without further throttling said pilot valve.

5. In a burner control system, a main burner, a pilot burner, a main valve controlling flow of fuel to said main burner, a pilot valve controlling fiow of fuel to said pilot burner, automatic means controlling said pilot valve, thermal means variably responsive to the heat output of the pilot flame and controlling operation of said main valve, and means operatively interconnecting said main valve and said pilot valve and operable upon predetermined opening of said main valve to throttle said pilot valve proportionately to the extent of opening of said main valve beyond said predetermined opening.

6. An automatic valve assembly comprising a first valve having an operating stern, a second valve having an operating stem, means for moving said first valve stem, means for moving said second valve stem independently of said first valve stem, said second-named moving means being capable of overpowering said first-named moving means, a lever mechanism positioned to transmit movement from said second valve stem to said first valve stem and movable by said second-named moving means, said lever mechanism being positioned to have a predetermined lost motion relative to one of said valves when both valves are closed and to engage operatively both valves when opened a predetermined amount, and said lever mechanism being operable when moved by said second-named moving means beyond the predetermined opening for said second valve to move said first valve toward closed position.

'7. A vaiveassembly as defined in claim 6 including means limiting movement of said one valve stem in a valve closing direction by said lever mechanism and including means carried on said lever mechanism permitting lost motion of the same relative to said second valve stem beyond the point of limitation of movement thereof.

8. A valve assembly as defined in claim '7 wherein the lost motion means carried on said lever mechanism comprises a collapsible spring arranged for transmission of movement to said second valve stem and collapsible only upon movement of said lever beyond the point of limitation of movement of said second'valve stem.

9. An automatic valve assembly comprising a .-first valve having an operating stem, a second -valve havingan-operating stem. thermally 0perated means for moving said first valve stem, means for moving said second valve stem independently of said first valve stem, and means comprising a lever mechanism operatively interconnecting said stems and having lost motion relative to one of them, said lever mechanism being movable by said thermally operated means and upon predetermined movement thereof in a valve opening direction to move said second valve stem in a closing direction in opposition to said second valve stem moving means.

10. An automatic valve assembly comprising first valve having an operating stem, a second valve having an operating stem, thermally operated means for moving said first valve stem, a pivoted arm for moving said second valve stem independently of said first valve stem, a second pivoted arm arranged to have lost motion relative to said first valve stem and to engage the same in a valve closing direction, and said second arm being arranged for operation by said first named arm.

11. An automatic valve assembly comprising a first valve having an operating stem, a second valve having an operating stem, thermally operated means for moving said first valve stem, an electric heat motor for moving said second valve stem independently of said first valve stem, and means comprising a lever mechanism operatively interconnecting said stems and having lost motion relative to one of them, said lever mechanism being movable by said thermally operated means and upon predetermined movement thereof in a valve opening direction to engage and move said second valve stem in a closing direction in opposition to said heat motor.

12. In a burner control system, a main burner, a pilot burner, a main valve controlling flow of fuel to said main burner, a pilot valve controlling fiow of fuel to said pilot burner, automatic means controlling said pilot valve, thermal means responsive to pilot flame and controlling operation of said main valve, and means to throttle said pilot valve upon predetermined opening of said main valve and comprising a lever actuated by said main valve upon predetermined opening movement thereof and movable into valve closing engagement with said pilot valve.

- 13. In a burner control system, a main burner, a pilot burner, a main valve controlling flow of fuel to said main burner, a pilot valve controlling flow of fuel to said pilot burner, electric means for operating said pilot valve, electric ignition means for igniting fuel at said pilot valve, a circuit including a room thermostat operable to energize simultaneously said valveoperating means and said ignition means, and thermal means responsive to the occurrence of flame at said pilot burner and operable to open said main valve, and means to throttle said pilot valve upon predetermined opening of said main valve and comprising a lever actuated by said main valve upon predetermined opening movement thereof and movable into valve closing engagement with said pilot valve.

14. In a burner control system, a main burner, a pilot burner, a main valve controlling flow of 11 fuel to said main burner, a pilot valve controlling flow of fuel to said pilot burner, electric means for operating said pilot valve, electric ignition means for igniting fuel at said pilot burner,'a circuit including a room thermostat operable to energize simultaneously said valve operating means and said ignition means, thermal means comprising a heat motor variably responsive to the heat output of the pilot flame and operable directly to open said main valve in proportion to the heat output of the pilot flame, and means operatively interconnecting said main valve and said pilot valve and operable upon predetermined opening 01 said main valve to throttle said pilot valve proportionately to the extent of opening of said main valve beyond said predetermined opening.

EARNEST J. DILLMAN. JACK E. FLEURY.

REFERENCES CITED Name Date Powers Apr. 1, 1890 Number Number 12 Name Date Schroder May 6, 1913 Blanchard Oct. 25, 1921 Sieben Nov. 6, 1928 Hulchinson Apr. 29, 1930 ValJean Dec. 16, 1930 Te Pas Jan. 19, 1932 Haire Feb. 6, 1934 Kimball May 1, 1934 Berghoefer Jan. 22, 1935 Royce Sept. 24, 1935 Pfau Jan. 12, 1937 Kuempel May 18, 1937 Bryant Aug. 31, 1937 McCorkle Jan. 16, 1940 Beggs May 14, 1940 Howard July 29, 1941 Levine Jan. 6, 1942 Mayner Apr. 7, 1942 Breese Sept. 21, 1943 Dillman Nov. 30, 1943 Justus Feb. 15, 1944 Harris Nov. 14, 1944 Blauvelt May 8, 1945 Landon Feb. 8, 1949

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