US2800544A - Combined pilot and ignition control device - Google Patents

Description

July 23, 1957 M. J. CAPARONE COMBINED PILOT AND IGNITION CONTROL DEVICE Original Filed Oct. 21, 1949 2 Sheets-Sheet l mm. Nk

INVENTOR. MIb/Meel Jymrozze.

HIS' TTORIVEY July 23, 1957 M. J. cAPARoNE COMBINED PILOT AND IGNITION CONTROL DEVICE Original Filed Oct. 2l, 1949 2 Sheets-Sheet 2 HIS' AZTTORJVZ'Y JNVENToR. Michael J @zvwze BY United States Patent C COMBINED PILOT AND IGNITION CONTROL DEVICE Michael J. Caparone, Arcadia, Calif., assignor to Robertshaw-'Fulton Controls Company, Greensburg, Pa., a corporation of Delaware Original application October 21, 1949, Serial No. 122,618, now Patent No. 2,667,217, dated January 26, 1954. Divided and this application April 2, 1953, Serial No. 346,451

3 Claims. (Cl. ZOO-61.86)

This application is a division of my copending application Serial No. 122,618, tiled October 21, 1949, now Patent No. 2,667,217.

rlfhis invention relates to pilot controls combined with an igniting means for gaseous fuel burners and particularly adapted for rst automatically igniting a main burner and thereafter causing the supply of fuel to be shut-off should a pilot flame become extinguished.

A relatively simple system for the foregoing purposes may employ a combustion responsive device associated with the pilot burner for opening the main burner valve during normal running conditions but causing this valve to close in the event of failure of the pilot flame. Such a system may be of the recycling type wherein the automatic closing of the valve is accompanied by another ign'iting operation of the pilotu burner. However, during the time required for the combustion responsive device to cause closing of the valve there may be an escape of a considerable amount of nnburned fuel into the burner chamber. would give rise to dangerous conditions due to this collection of unburned fuel becoming ignited.

The present invention seeks to avoid such conditions by providing a purge period in a recycling system so that no reignition can occur until a predetermined lapse of time following the valve closure. The apparatus requires no attention on the part of the operator to place it in operation beyond the customary turning on of the usual gas cock. The holding down of push buttons and the like is completely eliminated together with the waiting period prior to placing the system in operation. The apparatus requires a minimum number of parts which may be of simple design and should be economical to manufacture while requiring infrequent service when installed.y v

A single casing is preferably employed for housing the control valve and the igniter control means. These de vices are disposed side-by-side and a pair of lever means extend between them. One lever means is pivoted on the casing and overlies the control valve. A second lever means is pivoted intermediate its ends in the casing independently of the first lever and has one arm operatively engaging the rst lever and another arm operatively engaging the igniter control. The control valve is biased closed while the igniter control is biased to an inoperative position. However, due to the interposition of the levers the control valve bias serves to hold the igniter control in its operative position whenever the control valve is closed.

A thermally responsive device has an actuating element positioned in the casing and engageable with the one arm of the second lever. The actuating elementis movabled when the device responds to the heat of a pilot burnerflame for reversing the positions of the control valve and the ignited control so that when the main burner becomes operative then the igniter is no Ilonger in operation. As will be apparent from the detailed An immediate reigniting operation I 2,800,544 Patented July 23, 1957 description which now ensues, the control valve and iguiter control are operative in sequence in both directions for the purpose of providing a purge period as previously described.

In the drawings:

Fig. l is a schematic plan View, partly in section, of the automatic pilot control and ignition apparatus installed in a fuel burning system;

Fig. 2 is a similar schematic plan view, partly in section, of a modied form of automatic pilot control and ignition apparatus; and

Fig. 3 is a section taken along the line III-III of Fig. 2.

Main shut-oy? cock and thermostat Referring more particularly to Fig. l of the drawings, a main burner 10 is shown as adapted to receive a supply of fuel from a manifold 12 by way of a main fuel pipe 14. In one contemplated installation the main burner 10 is located in the oven burner compartment of a domestic gas range and the manifold 12 extends along the front of the range as is customary in such appliances. The usual main shut-off cock 16 has an inlet connected as by the elbow 18 to the manifold 12 and the o-utlet therefor is connected to one end of the main fuel pipe 14. It will be understood that the main shut-oif cock 16 may embody the usual oven thermostat operable by the single dial 20, such devices being disclosed in Weber Patent No. 2,303,011, for examle.

A pilot burner 22 is located in lighting proximity to the oven burner 10 and receives a supply of fuel by way of a conduit 24 connected to the main shut-oif cock 16. Preferably, the flow of fuel in the conduit 24 should by-pass the thermostat when such device is combined with the main fuel cock 16. Otherwise the conduit 24 could well be connected to the main fuel pipe 14 at the outlet of the main shut-olf cock. As such modifications are well known to those skilled in the art further description is deemed unnecessary, it being understood that rotation of the dial 20 to the off position will serve to shut off the flow of fuel in both the main fuel pipe 14 and the conduit 24.

Automatic pilot control and ignition device The automatic pilot control and ignition apparatus of this invention is embodied for the most part in a casing 26 which is interposed in the main fuel supply pipe 14. Thus, the casing 26 is provided with an inlet 28 and an outlet 30 at opposite ends thereof to which the main fuel pipe 14 is connected. A valve chamber 32 is formed in the casing 26 intermediate the inlet 28 and outlet 30 and is provided with an annular valve seat 34 intersecting the passage between the inlet 28 and the outlet 30. A control valve member 36 is positioned in the chamber 32 and is movable between open and closed positions relative to the valve seat 34 for controlling the How of fuel in the supply pipe 14. A coil spring 38 is operative between the casing 26 and the valve member 36 for biasing the latter towards the valve seat 34 and thus to its closed position.

The valve member 36 is provided with a valve stem 40 which projects into` a recess 42 formed in the upper face of the casing 26 axially of the valve seat 34 and terminating at a partition 43 overlying the valve seat 34. The recess 42 contains a snap-action mechanism of wellknown form including an overcenter snap or clicker disc 44 which engages the projecting end of the valve stem 40 and a thrust element 46 which projects through the usual sealing ring 48 for the snap-action mechanism. It will be understood that the contour of the snap disc 44 is reversed from that shown in the drawing upon sufiicient pressure being applied to the thrust element 46.

The conventional snap-action means thus briefly described is capable of overcoming the bias of the valve member 36 and moving the same to an open position relative to the valve seat 34.

The force required to rmove the thrust element 46 is applied through a rst lever 50 which is pivoted at one end on a bracket 52 carried by the casing 26 and partly overlying the recess 42. The opposite end of the lever 50 forms an operating arm which overlies the thrust element 46 and then projects upwardly at an oblique angle therefrom for a purpose apparent hereinafter.

A second lever 54 is pivoted intermediate its ends in a bracket 56 which is carried by the casing 26 on the opposite side of the recess 42 from the first bracket 52 and also partly overlying the recess 42. One arm of the lever 54 projects into overlying engagement with the upturned angular arm of the lever 50 and extends therebeyond toward the bracket 52 but terminating short thereof. The other arm of the second lever 54 extends on the opposite side of the bracket 56 into overlying relation with a control switch 58 which is carried on the upper face of the casing 26 on one side of the recess 42.

A flexible arm carrying a contact 60 forms part of the control switch 58 and is normally biased out of operative engagement with a xed contact 62 of the switch 58. An adjusting screw 64 projects from the lever 54 into operative engagement with the arm carrying contact 60 and serves to overcome the bias thereof when the parts are in the position shown in the drawing. Such position is due to the normal bias of the clicker disc 44 assisted by the bias of the valve spring 38 serving to rotate the lever 50 in a counterclockwise direction about its pivot on bracket 52 and in engagement with the lever S4 which thereupon rotates clockwise on its pivot on bracket 56 for the purpose described.

Combustion responsive device Thermally responsive means having a bulb 66, capillary tube 68 and an actuating element 70 form the combustion responsive device of this invention. The bulb 66 is positioned in the path of a llame from the pilot burner 22 and will be responsive to the heat thereof. The actuating element 70 has one or more flexible sides and is positioned in a cover 71 for the casing 26 which also houses the levers S0, 54 and the control switch 58. The actuating element 70 is supported axially of the valve seat 34 and in overlying relation with the adjacent arm of the lever 54 by a hollow stud 72 interposed between the adjacent ends of the capillary tube 68 and the element 70 and secured to the cover 71. A button 74 projects from the actuating element 70 into operative engagement with the adjacent arm of the lever 54 for transmitting movement of the actuating element 70 thereto.

The thermally responsive means comprising bulb 66, capillary tube 68 and actuating element 70 are charged preferably with mercury which is adapted to be completely vaporized at about 1000 F. so that no appreciable deflection of the actuating element 70 can occur above this temperature. Upon the bulb 66 becoming sutciently heated to cause such vaporization of the mercury charge, then the actuating element 70 will deflect and move toward the lever 54 sufficiently to operate the same. It will be apparent that this type of thermal element provides its own over-temperature safeguard due to the lack of movement beyond the set temperature. Furthermore, since the internal pressure must increase in order to cause movement of the actuating element 70 in a direction to open the valve member 36 then a leak or other failure of the thermal element is accompanied only by a safe-failure of the control apparatus.

Ignting means The system disclosed in this embodiment is completed by the provision of an electric igniter 76 which is positioned to ignite the fuel flowing from the pilot burner 22. A step-down transformer 78 is preferably employed in the electrical circuit of the igniter 76 together with a current limiting resistor 80. The electrical circuit of the igniter 76 will be described in connection with the description of the operation of the apparatus which follows immediately. A main switch 82 is preferably included in this circuit for operation to closed position when the main `shut-off cock 16 is opened by rotation of the dial 20.

Operation The parts are shown in Fig. l of the drawings in the positions they assume prior to the starting operation. Upon rotating the dial 20 of the main fuel cock 16 to an open position, fuel is permitted to ow in the main fuel pipe 14 as far as the control valve 36 which is biased closed. Fuel also flows in the conduit 24 to the pilot burner 22. The rotation of the dial 20 also causes the main switch 82 to be closed establishing a circuit for the igniter 76 which may be traced as follows: line wire 84, main switch 82, wire 86, igniter switch 58, wire 88, primary of thetransformer 78, wire 90, line wire 92. The transformer 78 being energized the circuit may further be traced from the upper terminal of the secondary of the transformer 78, line wire 94, resistor 80, Wire 96, igniter 76 and wire 98 to the lower terminal of the secondary of transformer 78.

Since the igniter 76 is now energized in the circuit just traced, then fuel flowing from the pilot burner 22 becomes ignited and begins to heat the bulb 66 of the temperature responsive means. When the bulb 66 becomes heated to the temperature which will vaporize the mercury contained therein then the vapor pressure so created moves the actuating element 70 to apply a force on the second lever 54. The resulting counterclockwise rotation of the lever 54 first causes the adjusting screw 64 carried thereby to become ineffective for overcoming the inherent bias of the flexible arm which carries contact of the igniter switch 58 which thereupon moves out of engagement with the contact 62. Consequently, the igniter circuit is opened and the igniter 76 becomes deenergized.

Continued movement of the diaphragm serves to further rotate the lever 54 in a counterclockwise direction causing corresponding clockwise movement of the first lever 50. When such movement has proceeded far enough, the thrust element 46 of the snap-action device exerts sufficient thrust to cause overcenter movement of ythe clicker disc 44 for overcoming the bias of the valve of the flow of fuel in the fuel pipe 14 by the thermostat to maintain the set temperature.

It will be observed that the operation of the igniter switch 58 and the valve member 36 to open position occurs in sequence. The bias of the clicker disc 44 must necessarily be overcome before the valve member 36 can move to its open position and this bias s assisted by that of the valve spring 38 tending to maintain the valve member 36 closed. The adjustment of the screw 64 determines the time during the cycle of operation that the igniter switch 58 opens. The movement of the screw 64 resulting from the expansion of the actuating element 70 is amplified by means of the lever S4 so that the screw adjustment is less critical. Moreover, the lever system tends to reduce the force which the actuating element 70 must overcome to initiate the desired control movements. In the illustrative embodiment disclosed herein the force required to ensure overcenter snap-action of the clicker disc 44 is reduced from approximately 30 to l0 pounds by operation of the levers 50, 54. While the described sequential operation occurs during both the starting operation describedy and van automatic shut-ofi, it has Vno' significance in the procedure for bringing the main burner into operation but does 'have considerable importance upon a reverse movement of the parts as will now be described.

In the event the ame of the pilot burner 22 is extinguished then the bulb element 66 will cool causing the 'actuating' element 70 to return towardits initial position. The ybias of the clicker disc 44 and the valve spring 38 are now effective for causing a return overcenter operaytion of the clicker disc 44 and movement of the valve member 36 Ato its closed position. During such return movement the' lever 50 is rotated counterclockwise by the thrust element 46 under the described bias and causes la corresponding clockwise movement of the lever 54. Upon sufficient movement of the actuating element 70 towards its initial position during further cooling of the bulb 66,v then the lever 54 rotates sufficiently in a clockwise direction to effect reengagement of the switch contacts 60, 62 of the igniter switch 58 and consequent reenerg'ization of the igniter 76. p s Y s It is apparent, therefore, that a definite period of time elapses after the control valve member 36 is closed before the igniter 76 is reenergized. This elapsed timel is termed a; purge period and permits yany unburned fuel remaining in the burner chamber to flow away before the igniting operation occurs and thus prevents explosions. This safeguard is obtained in the apparatus herein described by a simple adjustment of the screw 64 so that the switch 58 operates at a desired time during the cycle of operation.

Modified form, Fig. 2

Referring now more particularly to Fig. 2 of the drawings the apparatus previously shown and described has been modified to incorporate the so-called single point ignition. Thus, the electric ignition feature is eliminated and ignition of the main burner 10 is effected from a single central point such as from a constant burning pilot burner located on the top surface of a domestic gas range. As numerous parts embodied in the structure disclosed in Fig. 2 of the drawings merely duplicate those fully described and shown in connection with the Fig. 1 embodiment, similar reference numerals have been applied to these corresponding parts.

The casing 26 is substantially identical with that disclosed in the previous embodiment and is only slightly modified for the purposes of substituting a different control means for controlling the supply of operative energy to the igniter utilized in this alternative form. Thus, the inlet 28 is provided with a transverse passageway 100 extending through opposite walls thereof for the reception of a valve stem 102 carrying on one end thereof an auxiliary valve member 104. The valve member 104 is cooperable with an Vannular valve seat 106 forming part of the bottom wall of a recess 108 in the wall of the casing 26. The recess 108 is provided with a closure cap 110 which supports a valve spring 112 serving to bias the valve member 104 to a closed position relative to the seat 106.

An outlet 114 communicates with the chamber formed by the recess 108 and provides for ow of fuel to a conduit 116 secured to the Wall of the casing 26 and terminating at the opposite end in an ignition burner 118 positioned in lighting proximity to the pilot burner 22. Flow of fuel from the inlet 28 to the outlet 114 occurs past the valve stem 102 which is conveniently made of noncircular form in cross-section (in this case rectangular) for slidable engagement with the wall of the transverse passage 100 which is substantially circular in cross section. Thus the difference in the respective cross-sectional shapes of the valve stem 102 and the transverse passage 100 provides openings for the passage of fuel from the inlet 28a into the chamber formed by the recess 108.

The end of the valve stem 102 opposite the valve member 104 projects from the casing 26 into the cover 71 and asuitable sealing ring 120 is provided at the projectingv end to prevent leakage of fuel from the inlet 28. The operating means for the valve member 104 corresponding to the lever 54 of the previous embodiment is Vslightly modified to accommodate a longer adjusting screw 122 but is also pivoted intermediate its ends in the bracket 56.

As previously indicated, a constant burning pilot burner 124 which may be located on the top surface of a domestic gas range and supplied with fuel from the manifold 12 is relied upon as the original source for effecting ignition of the main burner 10 in this embodiment. To this end, a flash tube 126 is adapted to extend between the constant burner 124 and the ignition burner 118 for conducting a flame therebetween'. Inasmuch as the electric igniting means has been eliminated in this embodiment the dial 20 of the main fuel cock 1'6 does not require the addition of any switch means such as embodied in the previously described form.

peration of Fig. 2 embodiment In operation of the device disclosed in Fig. 2 of the drawings, the normal rotation of the dial 20 to an on position, or to set the oven temperature in the event that a combined thermostatic device is included therein, will serve to admit fuel to they pilot burner 22 and also in the main fuel pipe 14 as far as the control valve member 36 which is biased closed. Since the valve member 104 is at this time being held in an open position relative to its seat 106 fuel can liow past the valve stem 102 to the chamber formed by the recess 108 and thence through the outlet 114 and the conduit 116 to the ignition burner 118. This fuel enters the ash tube 126 and is ignited by the tiame of the constant burner 124 whereupon a iiash back occurs causing the ignition burner 118 to produce a fiame. In this manner, the fuel issuing from the pilot burner 22 is ignited and serves to heat the bulb 66 of the temperature responsive means as in the previously described embodiment.

During the initial portion of the resulting movement of the actuating element 70, the force exerted by the lever 54 for holding the auxiliary valve member 104 in an open position is relieved and this valve member becomes closed under the bias of its spring 112. Thereafter, the position of the Clicker disc 44 is reversed upon continued heating l of the bulb 66 and the control valve member 36 is moved to an open position to permit flow of fuel to the main burner 10. As such fuel is immediately ignited by the fiame from the pilot burner 22 the apparatus is placed in normal running condition under control of the main fuel cock 16 or the thermostatic device which may be associated therewith.

In the event that the liame at the pilot burner 22 is extinguished then the automatic pilot control comes into operation, The reverse movement of the actuating element 70 upon cooling of the bulb 66 first causes the Clicker disc 44 to resume its initial position with consequent closure of the control valve member 36 under bias of the valve spring 38. After a sufficient lapse of time for any unburned fuel to iiow away from the main burner 10, then the lever 54 is moved sufficiently in a clockwise direction by further contraction of the element 70 to reopen the auxiliary valve member 104 and admit fuel to the ignition burner 118 as described in connection with the starting operation. Thus, in this embodiment also a purge period is provided to prevent explosions caused by ignition of main burner fuel escaping during the time required for the bulb 66 to cool suficiently to close the control valve member 36.

It will be apparent that both embodiments provided control means movable between positions for controlling the supply of heat producing medium to an igniter. As only minor changes are required to adapt the control casing 26 for either electric or single point ignition, it

is apparent that the selection can readily be made. Both modifications are illustrated in schematic form but it will be apparent that various changes can be made to .adapt the apparatus for satisfactory commercial uses. Furthermore, many changes may be made in the details of construction and arrangement of parts Without departing from the scope of the invention as dened in the appended claims.

I claim:

1. An automatic pilot control and ignition apparatus comprising a casing having an inlet and an outlet intersected by a valve seat, a valve member biased to a closed position relative to said seat, operating means for overcoming said bias and moving said valve member to open position, control means positioned in said casing laterally of said valve member and being biased to one controlling position, a irst lever pivoted at one end on said casing and having an arm engageable with said operating means, a second lever pivoted intermediate the ends thereof on said casing and having one arm engageable with said first lever arm and having the other arm thereof operatively associated with said control means for holding the same in another controlling position, and a heat motor having an actuating element in said casing engageable with said one arm of said second lever and eiective for moving the same toward said tirst lever for overcoming the bias of said valve member for moving the same to an open position and elective for moving said control means to said one controlling position.

2. Apparatus as claimed in claim l wherein said other arm Vof said second lever is adjustable with respect to said control means for causing operation of said valve member and said control means in sequence.

i 3. Apparatus as claimed in claim 2 wherein said other arm of said second lever carries an adjustment screw for operative engagement with said control means, said operating means including an overcenter clicker disc where- Vby movement'of said levers in one direction by said ac- References Cited in the tile of this patent UNITED STATES PATENTS 2,214,272 Dillman Sept. 10, 1940 2,269,157 Levine Jan. 6, 1942 2,367,524 Ray Tan. 16, 1945 2,372,436 Landon Mar. 27, 1945 2,582,419 Dillman et al Jan. 15, 1952 2,583,795 Pamelsky et al. Jan. 29, 1952

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