US2745482A - Electric pilot-flame igniter - Google Patents

Description

y 15, 1956 a. c. DOUGLAS Em. 2,745,482

ELECTRIC PILOT-FLAME IGNITER 5 Sheets-Sheet 1 Filed Sept. 12. 1951 5 a. c. DOUGLAS arm. 2,745,482

awcmc PILOT-FLAME mama 3 Sheets-Sheet 2 Filed Sept. 12, 1951 y 15, 1956 a. c. DOUGLAS arm. 2,745,482

ELECTRIC PILOT-FLAME IGNITER s Sheets-Sheet 5 Filed Sept. 12, 1951 FIG .8.

FIG. I I.

2/9 FIG IO I I "ff FIG9.

United States Patent Oflicc 2,745,482 Patented, May 15,1958

ELECTRIC PILOT-FLAME IGNITER Bradley C. Douglas, Kirkwood, and Harry H. Pryor, St. Louis, Mo., assignors to Magic Chef, Inc., a corporation of New Jersey Application September 12, 1951, Serial No. 246,284

19 Claims. (Cl. 158-123) This invention relates to electrical pilot-flame igniters, and more particularly to apparatus of this class for use on gas ranges, stoves and the like.

Among the several objects of the invention may be noted the provision of a simple, highly compact and reliable fasbcycling type of electric pilot-flame igniter; the provision of a device of the class described which has an igniter coil removably mounted for convenient removal and replacement near a combined radiation guard and gas deflector for quick starting; and the provision of apparatus of the class described which is adapted to fit into the same small amount of space on gas ranges heretofore provided for ordinary pilot flames and their bonnets. Other objects will be in part apparent and in part pointed out hereinafter.

The invention accordingly comprises the elements and combinations of elements, features of construction, and arrangements of parts which will be exemplified in the structures hereinafter described, and the scope of which will be indicated in the following claims.

In the accompanying drawings, in which several of various possible embodiments of the invention are illustrated,

Fig. l is a vertical section with some parts shown in elevation, illustrating the application of one form of the present invention to a gas range;

Fig. 2 is a top plan view of Fig. 1;

Fig. 3 is a greatly enlarged cross section of one form of the device, viewed on line 3-3 of Fig. 2 (parts being shown in elevation), the dotted parts D illustrating a removed condition of an igniter plug;

Fig. 4 is a vertical section taken on line 4-4 of Fig. 3;

Fig. 5 is a horizontal section taken on line 5-5 of Fig. 3;

Fig. 6 is a vertical section taken on line 6-6 of Fig. 5 but with a bonnet removed;

Fig. 7 is a side elevation viewed on line 7-7 of Fig. 5

' but with said bonnet removed;

Fig. 8 is a plan view of another form of the invention, its bonnet being broken away to show interior parts;

Figs. 9 and 10 are vertical sections taken on lines 9-9 and 10-10 of Fig. 8;

Fig. ll is a side view of the igniter plug shown in Fig. 8, as viewed from line 1111 on Fig. 8; and

Fig. 12 is an enlarged detail cross section of a knifeedge pivot of a switch-operating lever of the form of the invention shown in Figs. 8-11.

Similar reference characters indicate corresponding parts throughout the several views of the drawings.

Referring now more particularly to Figs. 1 and 2 of the drawings, there is shown at numeral 1 the usual top sheet of a range or stove, above which is located a burner support 3. Ordinarily such a support carries a group, such as for example, a pair of burners, one of which is shown at 5, each having an ignition port 7. Between the burners there is a circular support 9 for ignition tubes 11, each of which extends from a common location such as L, into proximity to one of the ignition ports 7. The

pilot flame is usually maintained at L, so that when gas is admitted to the burner 5, some escapes from the ignition port 7 and passes through the adjacent ignition tube 11 into contact with the pilot flame. The result is a flash-back to the burner 5, which ignites it. Ordinarily the flame at L is constantly burning while the range is on duty. Gas is simultaneously admitted through a valve (not shown) to the pilot flame and to the burner 5. The pilot flame is ignited by an electric igniter coil. The coil is energized through a thermally operated normally closed pilot switch (to be described) and a main switch (not shown) which is closed at the same time that the gas is turned on. After the pilot flame ignites, its heat opens the thermally operated pilot switch thereby deenergin'ng the igniter coil. When the gas supply to the burner and to the pilot flame is cut 011, the main switch is opened. Cooling of the thermally operated pilot switch closes it ready for a subsequent operation. It is unnecessary to disclose the details of the main gas valve and main switch, since they are not necessary to a full understanding of the present invention and are not claimed herein. Moreover, the relationship of the main gas valve and main switch to each other and to the remainder of the apparatus is described in the copending, coassigned patent application of Almer H. Brodbeck and Bradley C. Douglas (one of the inventors herein) for Gas Burner Ignition System, Serial No. 244,142, filed August 29, 1951. The invention herein relates to the combination of parts to be incorporated in the small space at L within the support 9.

The invention per se is built on an angle iron support 13, bolted to the top sheet 1 (Figs. 1 and 3). This includes a vertical slot 15 for a bolt 17 which holds a bracket 19 for vertical adjustment. The bracket 19 includes a small platform 21 in which are slots 23 for removably snugly fitting tongues 25 of an enclosing protective bonnet 27. Obviously other means may be employed for holding the bonnet 27 on the platform 21. This bonnet has a hole 28 in its top, exposing the flame F (Figs. 1 and 3). In the platform 21 are openings 29 (Fig. 5) for convection of air to support combustion at the flame. Excess air escapes along with the flame out of the opening 28.

The flame F is generated from a nozzle 31 which has a threaded lower end 33 passing through the platform 21 where it is engaged by a threaded inlet nut 35. A coupling 37 threaded to the nut 35 serves to supply gas to the nozzle 31 from a gas supply pipe 39. The home has an outlet 32 at the bottom of a slot 34 cut across its upper end.

Attached to the platform 21 is a U-shaped support 41 open at the top having legs 57 and 59 and side-struck earn 43 and 45, the latter having an upwardly struck anchor 47 (Fig. 6). Threaded through one leg 57 of the support 41 is an adjusting screw 49. Spaced from the slotted head 51 of screw 49 is a shoulder 50 which upon assembly can pass through opening 52 in leg 59, but head 51 cannot. A horseshoe spring washer 54 between shoulder 50 and leg 59 prevents axial movement of screw 49 in leg 59 but permits its rotary movement. Thus when the screw is turned, the two legs 57 and 59 of the U-shaped member 41 may he sprung toward or away from one another. Struck out from the lower end of leg 59 is a tongue 61 for mounting a stationary switch contact 63.

On the car 43 is located a pivot 65 for a bell crank shown generally at 67. This bell crank has a relatively short arm 69 carrying a struck-up tongue 71. It also has a relatively long arm of generally zig-zag shape, consisting of a short horizontal section 73, a section in a vertical plane and a horizontal section 77. The latter passes through a lower opening 79 in the leg 59 at which point it has an ear 60 carrying a contact 81 opposite the stationary contact 63. Thus contact 81 is movable when the bell crank 'Ihenitthewireisheateditextends,md springfiwillbiasthebellcrankflinadirectiontodraw contact 81 from the contact 63. The heat-expanded the dotted-line position shown at D in Fig. 3. Its poles are shown at 105, and these are respectively in currentconductive relation with L-shaped conductive cleats 167. A heater coil 109 connects the cleats 107. This coil reaches gas ignition temperature when electrically excited. 'Ihe circuit for excitation is from the wire 101, through one set of poles of socket 97 and plug 103, igniter coil the other set of poles of plug 103 and socket 97, then via wire 99 to the stationary contact 63. If this contact 63ishycontact 8l,thenthecurrentmayflow through the hell crank lever 67 to ground through 41, 11, 19, 13 and 1. ltcontacts 63, 81 are separated, thiscircuit isbrokemaswhenthewire (whichisnotintheelectric circuit) is heated by the flame F.

The line 101 is supplied through a suitable transformer, reducing the voltage to a low-arcing order of 6 v. This avoids the necessity for ,elaborate quick-break arc-preventative action in connection with the contacts 63, 81. Ontheotherhanithisalsorequiresaverysmallcross section ofwireinthe ignitercoil 109inordertoreachignih'on temperature. Such a coil may be easily damaged by direct radiation from the closely adjacent part of flame F, particularly over long intervals of time. Any attempt to use an ordinary guard for protection prevents quick ignition. Therefore a special guard is provided, which is shown in general at numeral 111 and consists of an L- shaped sheet of metal, the bottom 113 of which is held in place under the nonle 31, the vertical portion of which is constituted by a shield 115. This vertical shield 115 is shaped to permit interchange of plugs such as 103. At its upper end the shield is provided with a deflector scoop 118 struck in towards nozzle 31. Below the scoop 118 is an oppositely struck out, upwardly directed funnel 120. Plug 103 is grooved as at 98 to clear the funnel 120 upon plug removal and insertion. Scoop 118 and funnel 120 have a common opening 119 between them. The portion above scoop 11! serves to guard the coil 109 from direct radiation close to the flame F, i. e., the coil 109 cannot directly "see" the flame in a horizontal direction. When unignitedgasfirst startstoflowfromthe nozzle3l,some

.i ir

iiiiiii iscutotlfromline 101. Thisshutsofitheburnersand the pilot flame, whereupon wire very promptly cools, thusdrawingbackthebellcrankflagainstbiasofspring 83 to reclose the contacts 63, 81. -The device is then An advantage of the mechanical construction for the thermostatic switch consisting of the U-shaped member 41, the bell crank 67, wire 95 and contacts 63, 81 with the control screw 49 is that it is very compact and the contacts 63, 81 are at a downward location atone side and out of the high heating elfect of the pilot flame. Moreover, the U-shaped member 41 carries the anchor for the wire 95 over the contacts 63, 81, providing a relatively long reach to the point of connection with the bell crank stretch for a given temperature increase is a function of its 4 length and coetiicient of expansion.

The control afforded by the adjusting screw 49 provides not only for adjusting the open distance between the contacts 63 and 81, but provides for adjusting the contact pressure which controls the initial creep action of the switch before opening. Thus the initial creep movement may be increased or reduced. If the initial creep isincreased by tending to separate the legs 57 and 59, the opening time is increased, but at the same time the closing time is decreased and vice versa. Usually it is preferable to have the closing time less than the opening time, so that the switch is quickly prepared for recycling after the pilot flame is turned out. The adjusting method for accomplishing this, it will be seen, is very simple, lending itself to easy manufacture, assembly and final adjustment of the device.

An alternative form of the invention is shown in Figs. 8-12, having certain additional advantages. In this form, 213 indicates the angle iron support, 219 the bracket and 217 the adjustable fastener operative in connection with slot 215. The bracket 219 includes a platform 221 on which is a bonnet 227, removably held in place by means of an alignment tongue 223 and a holding bolt 220. Inlet ventilating openings in the platform 221 are shown at 229. An exit ventilating opening. 228 is shown in the bonnet 227.

On the platform 221 is a U-shaped support 241, held in place by a pilot gas nozzle 231 and its inlet fitting 235. Themember 241 has legs 257 and 259, which are struck out at their tops as indicated at 243 and 245. An upwardly extending car 247 from 245 forms an anchor for a thermal wire 295. The other end of the thermal wire 295 is anchored to an car 269 of a switch lever 267. This lever has a vertical part 275 and a horizontal part 277, the later being horizontally arched to clear the nozzle 231. A horizontal connection 200 between the short arm 269 and the vertical part 275 has a lateral extension 202 with struck-down ears 204. The bent-out portion 243 of leg 257 is notched, as indicated at 206, and sharpened along the bottom of the notch so as to provide a knifeedge pivot lincwhich is engaged by the inside corners between the ears 204 and the lateral extension 202. Thus a knife-edge pivot is provided at two spaced contact points for the switch lever 267, resulting in low friction and substantially no binding under adverse operating conditions. Engagement at the pivot is maintained by the holding effect of wire 295 and a tension coil spring 283. The latter is anchored at its lower end to a struck-out portion 208 from leg 257, and is anchored at its upper end at the elbow formed by the arm 269. Since the forces pro vided by the wire 295 and spring 283 are directed along opposite sides of the pivot line, the lever 267 cannot escape from its pivot. Nor can it move laterally because limited by engagement of cars 204 with inside end edges of the notch 206.

The extension 277 of switch arm 267 carries a movable contact 263 which engages a stationary contact 281 when the wire 295 is cold. The stationary contact 281 is mounted upon a tongue 210 which is struck out from the leg 259. The strike-out provides an opening 212 in the leg 259 through which the extension 277 passes. When the wire 295 heats and expands, the tension spring 283 rotates the switch lever 267 in a direction to move contact 263 away from contact 281.

Adjustment between legs 257 and 259 is provided by an adjusting screw 249 threaded into leg 257. Screw 249 has a head 251 and spaced fixed collar 250 forming a rotary but non-sliding connection between the screw and the other leg 259. Closing pressure is increased on the contacts 263, 281 when the legs 257 and 259 are adjusted apart by adjusting screw 249.

Mounted on the platform 221 is a two-pole electrical socket 297, one pole of which is wired to the stationary contact 281, as shown at 299. The other pole is connected to a current supply wire 101. At 303 is shown a removable two-pole electrical plug which may be applied to and removed from the socket 297. Its poles are shown at 305 and these are connected by a heater coil 309. Attached to the plug 303 by fastening 214 is a hood 311 having a back wall 313, and an inverted box-like canopy 315 which has a struck-out tongue or deflector scoop 317.

6 The tongue 317 is not sufliciently long to intersect at flame from the nozzle 231 but it will deflect an pufl or spreading efliux of gas to the coil 309. On the other hand, the tongue 317 provides a shielding eflect for the coil 309, that is, shading from the hottest radiation from the flame.

Operation of the form of the device shown in Figs. 8-12 is like that already described in connection with that shown in Figs. 4-7. Initially, when the wire 295 is cold, the lever 267 is in rotated position to close contacts 263 and 281, tension spring 283 being elongated. Then when the circuit is closed, the coil 309 is energized so as to ignite a flame at nozzle 231. This flame heats the wire 295, which elongates, whereupon the spring 283 rotates the lever 26'! to move contact 263 from contact 281. This breaks the circuit, thus deenergizing the coil 309.

It will be understood that in both forms of the invention reference to deenergization of coil 309 includes not only cases employing a circuit wherein the current is entirely cut oil from the coil when contacts 263, 281 are open, but cases in which a small amount of current is permitted to flow, but insuflicient to cause the coil to glow or reach ignition temperature. Such a circuit is shown in the application above referred to, being one in which a coil such as 309 has parallel connections to ground; one through contacts 263, 281, and the other through a signal lamp.

In view of the above, it will be seen that the several objects of the invention are achieved and other advantageous results attained.

As many changes could be made in the above constructions without departing from the scope of the invention, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

We claim:

1. An electrical pilot igniter comprising a support, a gas nozzle on said support adapted to produce a flame,

a thermal switch on said support consisting of an upwardly open U-shaped member having upright legs, a stationary contact at the lower end of one leg and an anchor at its upper end, a bell crank lever pivoted at the upper end of the other leg and having a relatively short arm, a thermal wire connecting said anchor and said short arm and located in heat-exchange relationship with said flame, said bell crank lever also having a relatively long arm extending downward between the vertical legs of the U- shaped member, a movable contact on the end of said long arm engageable with said stationary contact, and an adjusting means between said vertical legs and adapted to move them apart or together, whereby the contacts may be predeterminately set for predetermined opening and closing actions.

2. An electrical pilot igniter comprising a support, a gas nozzle on said support, a thermal switch on said support consisting of an upwardly open U-shaped member having upright legs adjacent the nozzle, a stationary contact at the lower end of one leg and an anchor at its upper end, a bell crank lever supported upon a knifeedge pivot at the upper end of the other leg and having a relatively short arm opposite the anchor on said one leg, a thermal wire connecting said anchor and said short arm and stretched crosswise at the flame, said bell crank lever also having an angled relatively long arm extending downward between the vertical legs of the Ushaped member, a movable contact on the end of said long arm engageable with said stationary contact, at least one of said vertically disposed legs having an outwardly directed car, which provides said knife-edge for the pivot of the bell crank lever.

3. An electrical pilot igniter comprising a support, an upright gas nozzle on said support, a switch on said support consisting of an upwardly open U-shaped member having upright first and second legs, said legs having first amuse 7 sndsecondlateralcpeningsrespectivelyattheirbases,

a stationary contact at the lower end of the flrst leg and snanehorattheupperendotthisleg, abellcranklever pivoted at the upper end of the second leg and having a relatively short arm opposite said anchor on the first leg, a thermal wire connecting said anchor and said short arm andpcsitionedtoreceive heatfromaflameissuingfrom the nozzle; said bell crank lever also having an angled relatively .long arm extending downward between the legs and outward through said first opening adiacent'the stationary contact, a contact at the outside end of said long arm engageable with said stationary contact, and a coil spring anchored outside of the U-shaped member on the side opposite the stationary contact and extending through said second opening in said second leg and engaging one arm of the bell crank lever, said spring biasing said bell crank lever in a direction to disengage the contacts.

4. An electrical pilot igniter comprising a support adapted to produce a flame, a gas nozzle on the support, a thermal switch on said support consisting of an upwardly open U-shaped member having upright legs, a stationary contact at an opening near the lower end of one leg and an anchor at its upper end, a bell crank lever supported upon a knife-edge pivot at the upper end of the other leg, said bell crank lever having a relatively short arm extending upward from said pivot,a thermal wire connecting said anchor and said short arm and located in heat-exchange relationship with said flame, said bell crank lever also having a relatively long arm extending downward between the vertical legs of the U-shaped member and through said opening, a movable contact at the end of said long arm engageable with said stationary contact, said lever being movable in a vertical plane, and a tension spring anchored to the support and to said short arm, said wire and spring being adapted to hold the lever on said knife-edge pivot.

5. An electrical pilot igniter made according to claim 4, including an adjusting means extending between said legs for adjustably spreading them apart or bringing them together.

6. An electrical pilot igniter comprising a support, a gas nozzle on said support, a thermal switch on said support consisting of an upwardly open U-shaped member having upright legs, a stationary contact at the lower end of one leg and an anchor at its upper end, a bell crank lever pivoted at the upper end of the other leg and having a relatively short arm, a thermal wire connecting said anchor and said short arm, said bell crank lever also having a relatively long arm extending downward between the vertical legs of the U-shaped member, a movable contact on the end of said long arm engageable with said stationary contact, an electrical socket located on the support adjacent said U-shaped member and wired into a circuit with said switch, a removable plug in said socket and including an igniter coil adapted to be placed in said circuit when the plug is applied to the socket.

7. An electrical pilot igniter made according to claim 6. wherein the nozzle is located between said coil and said thermal wire and between said legs.

8. An electrical pilot igniter made according to claim 7, including a gas deflector and a flame shield associated with the coil.

9. An electrical pilot igniter comprising a support, an upright gas nozzle on said support, a switch on said support consisting of an upwardly open U-shaped member having upright first and second legs, said legs having first and second lateral openings respectively at their bases, a stationary contact at the lower end of the first leg and an anchor at the upper end of this leg, a bell crank lever pivoted at the upper end of the second leg and having a relatively short arm opposite said anchor on the that leg, a thermal wire connecting said anchor and said short arm and positioned to receive heat from a lame issuing from the nozzle; said bell crank lever also 8 having an angled relatively long arm extending downward between the legs and outward through said first opening adjacent the stationary contact, a contact at the outside end of said long arm engageable with said stationary contact, and a coil spring anchored outside of the U-shaped member on the side opposite the stationary contact and having an arm extending through said second opening and engaging the long arm of the bell crank lever at a location between said vertical legs of the U-shaped member, said spring biasing said long arm in contactopening direction. l0. An electrical pilot igniter made according to claim 9, including a screw control between said vertical legs and adjacent said long arm of the bell crank lever and adapted to move said vertical legs together or apart.

11. An electrical pilot igniter comprising a support adapted to produce a flame, a gas nozzle on the support, a thermal switch on said support consisting of an upwardly open U-shaped member having upright legs adapted to be sprung apart, an anchor at the upper end of one leg, a stationary contact, a bell crank lever pivoted at the upper end of the other leg and having a relatively short arm, a thermal wire connecting said anchor and said short arm and located in heat-exchange relationship with said flame, said bell crank lever also having a relatively long arm, a movable contact on the end of said long arm engageable with said stationary contact, and an adjusting screw mounted between said vertical legs and adapted upon rotation to move them apart or together, whereby the contacts may be set for predetermined opening and closing actions.

12. An electrical pilot lighter igniter made according to claim ll, wherein the pivot for the bell crank lever is of the knife-edge variety, a tension spring mounted to bias the bell crank lever in a direction to open the contacts, the directional thrusts of said spring end of said wire being arranged at an angle to include the pivot, whereby separation is prevented of the bell crank lever from the supporting leg at the pivot.

13. An electrical pilot igniter comprising a support, an upwardly directed gas nozzle on said support, the outlet of said nozzle having a transverse slot, adapted, when gas flow is initiated but is unignited to produce an efllux of gas of substantial spread parallel to the slot and when ignited to produce a flame of substantially less spread, igniter elements adjacent the location of the efliux and flame and including an ignition wire and a deflector, said deflector having a margin extending generally transversely to the slot and being positioned in the normal path of initially spreading efllux of unignited gas and shaped to deflect some of it to the ignition wire and being located to be passed by said flame of less spread without deflecting any of it and to shade said wire against such radiation from the flame as may be damaging to the ignition wire.

14. A pilot igniter made according to claim 13, wherein the ignition wire of said igniter elements is mounted upon an electric plug assembly, and wherein said support carries electrical contact means for the removable reception of said plug assembly.

13. A pilot igniter made according to claim l4, wherein said deflector is also carried upon the removable plug assembly.

16. A pilot igniter made according to claim 14. wherein said deflector is permanently carried upon the support and independently of said removable plug assembly.

17. An electrical pilot igniter comprising a support, a gas noule on said support adapted to produce a flame, a thermal switch on said support consisting of an upwardly open U-shaped member having upright legs, a stationary contact located adjacent the lower end of one leg and an anchor at its upper end, a bell crank lever pivoted at the upper end of the other leg and having a relatively short arm, said bell crank lever also having a relatively long arm including one part extending downward relative to the vertical legs and another part extending crosswise of the legs, a movable contact on the end of said long arm engageable with said stationary contact, a thermal wire connecting said anchor and said short arm and located in heat-exchange relationship with said flame, said thermal wire when cold being adapted by contraction to bias the contacts toward engagement, a spring reacting between the bell crank lever and the support and adapted to bias said contacts apart against the holding action of said thermal wire and tending to stretch the thermal wire, and electric circuit means including said contacts and said long arm of the bell crank lever.

18. An electrical pilot igniter made according to claim 17, including means for adjusting the tension in the thermal wire when cold against bias of said spring, whereby the contacts may be predeterminately set for predeterminate opening and closing actions in response to the presence or absence respectively of the flame.

19. An electrical pilot igniter comprising a support, an upwardly directed gas outlet noule on said support, the outlet of said nozzle having a slot, igniter elements adjacent the nozzle and including an ignition wire and a guard means adjacent it, said slot of the gas nozzle being adapted when gas is unignited to produce a spreading efliux of gas adapted to be caught by the guard means and directed into contact with the ignition wire and when gas is ignited to producc'a less spreading flame clearing the guard means and said ignition wire, said guard means forming a shade for the ignition wire against damaging radiation from the flame.

References Cited in the tile of this patent UNITED STATES PATENTS 2330.789 Browning Nov. 21, 1939 2,241,295 Clark May 6, 1941 2,296,686 Ragan Sept. 22, 1942 2,312,974 Owens Mar. 2, 1943 2,480,230 Elster Aug. 30, 1949 2,548,300 Garner Apr. 10,1951

FOREIGN PATENTS 288,188 Germany Oct. 26, 1915 494,216 Great Britain Oct. 21, 1938

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