US2012503A

US2012503A - Safety pilot light

Info

Publication number: US2012503A
Authority: US
Publication date: 1935-08-27
Anticipated expiration: 1952-08-27

Description

Aug. 27, 1935. F. A. GAUGER SAFETY PILOT LIGHT Original Filed April 5, 1930 2 Sheets-Sheet l ,6 211 ATTORNEY Aug. 27, 1935. F. A. GAUGER SAFETY PILOT LIGHT 2 Sheets-Sheet 2 Original Filed April 5, 1930 ATTORNEY Patented Aug. 27, 1935 UNITED STATES SAFETY PILOT LIGHT Frank A. Gauger, Milwaukee, Wis, assignor to Milwaukee Gas Specialty Company, a corporation 6: Wisconsin Original application April 5, 1930, Serial No.

Divided and this application Februmy 6, 1933, Serial No. 655,418

Claims. (C1. 158-1171) This invention relates to a safety pilot light. This application is a division ofmy copending application Ser. No, 441,836, filed Apr. 5, 1930, for Safety pilot light. 5 Objects of this invention are to provide a novel form of safety pilot light which may be mounted wholly within a combustion chamber, such, for example, as the combustion chamber of a furnace or other apparatus, which is so made that it will not respond to the general temperature or the radiated heat in the combustion chamber, but will respond only to the heat generated by the pilot light itself, such pilot light being so made and associated with a thermostatic member that II in the specific construction a portion oi the flame of the pilot light plays directly upon the thermostatic member.

Further objects are to provide a novel form of pilot light, combined as a unit with a thermostatic member, which is so constructed that the thermostatic member is directly carried by the pilot light and forms a unitary portiontherewith, in which the supporting structure for the combined pilot light. and thermostatic member is in reality the supply pipe and supply nozzle for the pilot light, and in which the construction is such that the entire pilot light and thermostatic control device may be bodily lifted from the supply pipe and supply nozzle, for repair or inspection, in a very simple and easy manner.

Further objects are to provide a novel form of safety pilot light in which the thermostatic member is quickly responsive, and is preferably so made that a positive stop is provided for arrestlog the motion of the movable portion of such' thermostatic member at one point in its travel to thus prevent excessive pressure being exerted upon the control member, and to so construct the thermostatic member and so associate it with the 40 pilot light that the maximum speed of response is obtained.

Further objects are to provide a, novel form of safety pilot light which is mounted, as pointed out above, wholly within the combustion chamher, but which, nevertheless, operates a control member located outside of the heated zone of the combustion chamber and protected from excessive heat, and preferably located within the incoming stream of secondary air, so that it is maintained in a fairly cool condition at all times and irrespective of the temperature within the provided with a control valve ll.

'pipe extends upwardly, as indicated at 12, and

an integral structure comprising the balanced U-tube pilot light, the thermostatic member, and the control member operated thereby, and to so associate these parts that there is an imperfect thermal conductivity path between the pilot light 5 and the supply nozzle, so that the supply nozzle does not become excessively heated, thereby avoiding carbonization and choking of such supsimple, which is easy to position and remove,

which is rugged, and which is not likely to get out of order. s r 15 Embodiments of the invention are shown in the accompanying drawings, in which:

Figure 1 is a sectional view through a portion of a furnace and through a part of the safety pilot light. 20

Figure 2 is an enlarged sectional view on the line 2-2 of Figure 1.

Figure 3 is an enlarged sectional view on the line 3--3 of Figure 1.

Figure 4 is a view corresponding to Figure 1 as showing a diilerent form of theapparatus.

Figure 5 is an enlarged sectional view on the line 5--5 of Figure 4.

Before entering the detailed discussion of this invention, it is to be noted that the pilot light is adapted to be positioned wholly within the combustion chamber, and is provided with a control member which is located outside of the combustion chamber, or at all events, outside of the heated zone of such chamber, and that the con- 35 trol member may be either an electrical control member or may be so constructed that it controls through the medium of gas pressure, or in a similar manner.

Referring to Figures 1 to 3 which show the first 0 form -of the invention, it is to be noted that a gas furnace has been indicated as provided with a casing I provided with a transverse portion 2, and forming a combustion chamber 3. A main burner ,4 is located within the combustion chama I her and is supplied from the main gas supply manifold 5, a valve 6 being provided between the manifold and the mixing tube I of the burner. The secondary air enters the space indicated at 8 and passes upwardly through the duct provided 50 by the auxiliary casing 9.

It is to be noted that a branch supply pipe l0 extends downwardly from the manifold 5. and is This branch provides a support for the safety pilot light. The portion l2 preferably is carried by a shouldered fitting l3, and is provided with a small supply nozzle I 4 at its upper end. I

The safety pilot light comprises a U-burner having two main passageways I5 and I6 which communicate by way of the intermediate passageway l'l. All of these passageways are formed in an integral casting I8 and it is preferable to provide a plurality of openings l9, which are in reality the openings at which the flames are formed. Preferably one opening I9 is on the upper side of the casting of the U-burner, as shown in Figure 1, and is located practically directly beneath the curved portion of the thermostatic member 26. This thermostatic member is locked to the casting l8 by means of a bolt 2| or other suitable member. This bolt has its head located below the free arm of the thermostatic member and provides a stop for such free arm to limit its downward motion. The free arm is provided with a substantially non-expanding metal projecting arm 22 which is riveted thereto or otherwise secured. This arm 22 is provided with an adjusting screw or contact member 23, which, when in adjusted position, is locked by means of the lock nut 24.

Returning to the U-burner of the safety pilot light, it will be seen that the casting I8 is bored and threaded to receive the Venturi insert tube 25 and the insert bushing 25, which latter receives the supply nozzle Hi and thus accurately aligns the nozzle with the Venturi tube 25. As a matter of fact, the holes for the Venturi tube 25 and the bushing 26 maybe readily bored out in the casing as they are in alignment, and thus it is a simple matter to bore and thread such holes. At this point it is to be particularly noted that there is only a sliding fit, which is fairly loose, between the supply nozzle M and the bushing 26. Consequently the thermal conductivity between the casting E8 of the U-burner and the supply nozzle I l is very poor. The result of this construction is that the supply nozzle is only slightly heated even when the apparatus is in continuous operation, and consequently carbonization and choking of the nozzle cannot occur. The casting i8 is rigidly carried by a sleeve or tube 2'! which forms an integral portion thereof and whose lower end is threaded into a casing 28 also formed as a casting. This casing 28 is provided with an apertured lip 29, which is slidably carried by the supply pipe i2, preferably fitting over the cylindrical portion of the fitting i3 and resting upon the lower shouldered portion of such fitting. The construction is such, therefore, that the U-burner of the safety pilot light is in reality carried by the supply pipe, the upper end of the safety pilot light fitting over the supply nozzle and the lower end being slidably carried and supported by the supply pipe.

Preferably the lower portion of the casing 28 is closed by means of an insulating bottom plate 30. This insulating bottom plate 30 carries a stationary contact member 3| and a U-shaped, movable, spring contact member 32. The movable contact member 32 is most clearly shown in Figure 3, and it will be seen that such member is provided with a lip or ear 33 underhanging the stationary contact 3| and with a lip or ear 34',

which is readily fastenedto the insulating base plate 30. Suitable binding posts 34 are connected to the contacts and also are connected to the conductors of a cable 35, see Figures 1 and 2. The cable 35 extends to the main control valve in the usual manner, so that when the contacts are closed, the valve is permitted to operate, but when the contacts are opened, due to the action of the material to thus electrically insulate the movable contact member from the metal rod.

From actual trials it has been foundthat there is a tendency for particles of dust to be drawn downwardly into the passageway l6. Obviously, irrespective of the minuteness of these particles, they will ultimately somewhat clog' or pack around the rod 35 if the rod is not protected therefrom. Consequently, a small, protecting sleeve or tube 38 loosely surrounds the rod 36 and is preferably threaded into the main casting iii of the U-burner of the pilot light, as shown in Figure 1. This sleeve 38 is relatively small and does not close the passageway I 6. Consequently air can flow between such tube 38 and the walls of the passageway it, and thus provide an adequate supply for the U-burner of the pilot light. However, inasmuch as the tube 38 projects upwardly a considerable distance, preferably to the top of the casting is, it is clear that the rod is guarded from accumulation of dust particles entrained with the air.

From the description thus far given, it is apparent that a balanced U-tube safety pilot light has been provided by this invention which is so made that it may be wholly mounted within the combustion chamber of a furnace or similar device, and which cannot be extinguished by explos ons or sudden variations of pressure occurring within such combustion chamber.

It is also apparent that very simple and easily constructed control means are provided and associated with the safety pilot light, and that excessive displacement of the elements of this control member is prevented by the manner in which the thermostatic apparatus is constructed, as previously described.

Although the operation is apparent from the previous description, it is believed a brief statement thereof is desirable.

When the pilot light is in operation, the thermostatic member 20 is heated and the arm 22 is moved upwardly, thus allowing the rod 36 to move upwardly and allowing closing of the contacts. As previously stated, any explosion, due to lighting or extinguishing of the main burner, produces the same pressure upon the opposite ends of the U-shaped burner of the pilot light and does not,

therefore, tend to extinguish such pilot light. The thermostatic member is so constructed that as long as it is heated, preferably directly by the pilot light, it will maintain the contacts closed. However, if the pilot light is extinguished for any reason, the thermostatic member then moves the arm 22 downwardly, forcing the rod 36 downwardly, and opens the contacts. This, in accordance with the well known practice, opens the circuit of the main supply valve and prevents supply of fuel to the main burner.

' The form of the invention shown in Figure 4 is substantially the same as that shown in Figure l, with, however, the exception that the control member is differently constructed. This control member operates a control valve by gas pressure in a well known manner.

The control member, in this second form of the invention, is the only differently constructed portion of the apparatus from that previously de scribed, and consequently such control member alone need be described.

This control member consists of a fitting 39 which carries a valve seat 40 adapted to cooperate with a ball valve ll. This ball valve is urged towards closed position by means of the helical compression spring 42, and is forced open by means or the rod 36 previously described. The.

lower portion of the fitting 39 is closed by a plug t3 screwed thereinto and carrying the compression spring 2. The supply pipe i2, similar to that previously described, is provided with a fitting M, which replaces the fitting 13, see Figure 1. The fitting it and the fitting 39 are provided with list faces, which may, take any shape. In Figure 4 the lace oi the fitting 46 is shown. These faces are drawn together, and consequently the fittings M and 89 are joined by means bolts or screws 45, preierably a washer l of paper, iiber, or similar material being interposed between such laces to insure a gas-tight joint.

A control pipe t'l leads outwardly to the control valve (not shown) from the fitting 3! and communicates with the space above the valve ll by means of a small duct 48. The interior of the supply pipe 2 communicates with the space below the valve M by means of a small duct 49. It is clear, thereforethat when the valve 4! is seated, which would correspond to the condition when the pilot light is lighted, no gas pressure is transmitted to the pipe ill post the control member, and, consequently, the control valve for the main burner is allowed to operate, as required, in the usual and well known manner. However, when the valve ll is displaced by the thermostatic member, gas pressure is communicated to the pipe 47 and the main control valve (not shown) is prevented from operating, and, consequently, no gas can pass to the main burner.

It is to be noted that the pipe to, which connects with the supply pipe I2, is to be connected to the supply mains ahead oi the automatic control valve (not shown) for the main burner, in the usual manner.

It is to be noted particularly that no studios box or packing is required for the rodas, as any gas that leaks past this rod in the normal operation of the apparatus is entrained with the incoming air for the pilot burner and consequently is consumed in the pilot burner. The gas passing the rod 36 is drawn through the port M and is thereby carried along with the mixture to the pilot burner.

It will be seen that means are provided intermediate the control member, whether it takes the form of the electric contacts shown in Figure 1 or the combustion chamber, and that this safety pilot light is not caused to operate by the general temperature or heat within the combustion chambar, but is responsive only to the heat generated by the pilot light.

It will also be seen that a very simple type of safety pilot light has been provided in each form of the invention which is easy to construct, which is substantially foolproof, which is positive in its operation, and which is truly reliable.

Although this inventionhas been described in considerable detail, it is to be understood that such description is intended as illustrative rather than limiting, as the invention may be variously embodied and is to be interpreted as claimed.

I claim: l. A unitary pilot light and thermostatic pilot switch device comprising. a main burner, a U-shaped pilot light for said main burner constituting a Bunsen burner, a fuel supply pipe for said pilot light, a thermostatic member carried by said pilot light and responsive thereto, a control device mounted as a rigid unit with. said pilot light and operated by said thermostatic member, said pilot light,-said thermostatic member and said control device forming a unitary structure supported from said fuel supply pipe and readily removable therefrom by a sliding motion longitudinally of said supply pipe.

2. A pilot light comprising a supporting fuel supply member provided with a fuel nozzle, a. U-tube body portion, one of its main arms being an air inlet and the other main am being a mii ture outlet, said fuel supply member forming the support for said body portion and said fuel nozzle having poor thermal connection with said body portion to prevent carbonization at the nozzle, and a thermostatic member carried by the said main arm forming the mixture outlet, said thermostatic member being responsive to saidpilot light, and control means'actuated by said thermostatic member.

3. A pilot light having a body portion provided with an air inlet and a fuel outlet, a fuel supply pipe having a nozzle opening into said body portion, said fuel supply pipe extending downwardly from the nozzle, supporting means rigidly connected with said body portion and extending downwardly from said body portion, said means being supported by said fuel supply pipe at a point remote from and below said nozzle and supporting said body portion, a thermostatic member carried by and responsive to said pilot light. and control means including means connecting the same to said thermostatic member and spaced downwardly therefrom and supported as a unit from said fuel supply pipe with said pilot light.

4. A pilot light having a body portion provided with an air inlet and a. fuel outlet, said fuel outlet constituting an extension projecting laterally from said air inlet, and said air inlet and said fuel outlet forming a U-burner, a fuel supply pipe having a nozzle opening into said body portion. said fuel supply pipe extending downwardly from the nozzle, supporting means rigidly connected with said body portion and extending downwardly from said body portion, said means being re= movably supported by said fuel supply pipe and supporting said body portion at a point remote from and below said nozzle, a thermostatic member carried by the laterally projecting extension of said pilot light and responsive to said pilot light, and a control device supported irom said body portion at a point spaced downwardly from said pilot light, said control device being operatively connected to said thermostatic member.

5. In a device of the class'described, a casing, a main burner located within said casing, a fuel sup- 5 ply, a fuel standard nozzle connected to said fuel supply, a 'U-tube Bunsen pilot light positioned within said casing and drawing its primary and secondary air from within said casing only, a

thermostatic member carried by said pilot light and responsive thereto, and a control device carried as a unit with said pilot light, said pilot light being detachabiy supported by said fuel standard nozzle and being readily lifted therefrom as a unit with said control device without disturbing the adjustment of said thermostatic member.

FRANK A. GAUGER.