US1960777A

US1960777A - Safety pilot light

Info

Publication number: US1960777A
Authority: US
Publication date: 1934-05-29
Anticipated expiration: 1951-05-29

Description

F. A. GAuGl-:R 1,960,777

SAFETY PILOT LIGHT Filed A .pril 5. 1930A 2 Sheets-Sheet 1 May 29, 1934.

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May 29, 1934. F. A. GAuGl-:R

SAFETY PILOT LIGHT Filed April l 5, 1950 2 Sheets-Sheet 2- l Patented May 29,. 1934 n UNITED STATES SAFETY rmoT LIGHT Frank A. Gauger,

Milwaukee,l Wis., assignor to Milwaukee Gas Specialty Company, a corporation of Wisconsin Application April 5, 1930, Serial No. 441,836

4 Claims.

This invention relates to a safety pilot light. Objects of this invention are to provide a novel form of safety pilot light which maybe mounted wholly within a combustion chamber, such, for 5 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 pilotlight itself, such pilot light being so made and associated with a thermostatic member that in the specific construction a portion of 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 portion therewith, in which 20 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 balanced safety pilot light which, in the specific form, consists of a U-tube, both ends of which are subjected to the same pressure so that a sudden change of pressure, as, for instance, an explosion in the main combustion chamber, will not interfere with the free flow of combustible mixture through the pilot light and consequently will not extinguish such pilot light.

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 arresting the motion ofthe 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 s o associate it with the 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 chamber, 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 .which is rugged, and which is not likely to get -maintained in a fairly cool condition at all times and irrespective of the temperature Within the combustion chamber. In greater detail, objects of this invention are to provide a safety pilot light in which a tubular member, provided with a supply nozzle, supports an integral structure comprising the balanced U- tubepilot 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 and the supply nozzle, so that the supply nozzle does not become excessively heated, thereby avoiding carbonization and choking of such supply nozzle.

Further objects are to provide a novel form of construction of safety pilot light in which a Venturi tube is carried by the U-shaped pilot light, and when the structure is assembled and carried by the supply pipe and supply nozzle, is located directly in alignment with such supply nozzle, thereby insuring adequate entrainment of air, although the U-burner of the pilot light is relatively small.

Further objects are to provide a construction for a safety pilot light which may be manufacvtured with the utmost ease, which is extremely simple, which is easy to position and remove,

out of order.

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. I

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 showing a different form of the apparatus.

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, andis 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 control 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 furnace has been indicated as provided with a casing-1 provided with a transverse portion 2 and forming a combustion chamber 3. A main burner 4 is located within the combustion chamber and is supplied from the main gas supply manifold 5, a valve 6 being provided between the manifold and the mixing tube 7 of the burner.`

The secondary airenters the space indicated at 8 and passes upwardly through the duct provided.

portion 12 preferably is carried by a shouldered fitting 13, and is provided with a small supply nozzle 14 at its upper end.`

'I'he safety pilot light comprises a U-burner having two main passageways 15 and 16 which communicate by way of the intermediate passageway 17. All of these passageways are formed in an integral casting 18 and it is preferable to provide a plurality of openings 19, which are in reality the openings at which the flames are formed. Preferably one opening 19' 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 20. This thermostatic member is locked to the casting 18 by means of a bolt 21 or other suitable member. This bolt has its head located below the free arm of the thermostatic member 20 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 18 is bored and threaded to receive the Venturi insert tube 25 and the insert bushing 26, which latter receives the supply nozzle 14 and thus accurately aligns the nozzle with the Venturi tube 25. As a matter of face, the holes for the Venturi tube 25 and the bushing 26 may be readily bored out in the casing as they are in alignment, and thus it i's a simple matter to boreand thread such holes.

At this point it is to be particularly noted that there is only a sliding fit, Vwhich isfairly loose, between the supply nozzle 14 and the bushing 26. Consequently the thermal conductivity between the casting 18 of the U-burner and the supply nozzle 14 is very poor. The result of this construction is that the supply nozzle is only slight- .ly kheated even when the apparatus is in continuous operation, and consequently carbonization and choking of the nozzle cannot occur.

VThe casting 18 is rigidly carried by a sleeve.- or tube 27 which forms an integralporti'on 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 12, preferably fitting over the cylindrical-portion of the fitting l13 and resting upon the lower shouldered portion cf 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 slidform of the invention, it is to be noted that a. gas

ably 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 31 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 31 and with a lip or ear 34', which is readily fastened to 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 v 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 thermostatic member,.the' main valve is` prevented from opening.

The means for operatively connecting -the thermostatic member and the movable contact may consist merely of a small rod 36 which extends directly downwardly from the adjustable contact or member 23 carried by the arm 22 of the thermostatic member and bearing at its lower 4endupon the spring or movable contact member 32, see Figure l. This rod may be provided with a slightly enlarged head 37 at its lower end, and it is preferable to form this head of insulating material to thus electrically insulate the movable contact member from the metal'rod.

From actual trials it has been found that there is a tendency for particles of dust to be drawn downwardly into the passageway 16. Obviously, irrespective of the minuteness of these particles, they w'll ultimately somewhat clog or pack around the rod 36 if the rod isnot protected therefrom. Consequently, a small, protecting sleeve or tube 38 loosely surrounds the rod 36 and is preferably threaded into the main casting 18 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 16. Consequently air can flow between such tube 38 and the walls of the passageway 16, and thus pro- From the description thus far given, it is apparent thatv 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 explosions 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 rpilot 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 ccntacts, As previously stated, any explosion, due j" to lighting or extinguishing of the main burner,

produces the same pressure upon the opposite supply valve and prevents supply of fuel to the main burner.

The form o f the invention shown in Figure 4 is substantially the same as that shown in Figlure 1, 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 described, and consequently such control member alone need be described.

-This control member consists of a tting 39 which carries a valve seat 40 adapted to cooperate with a ball valve 41. This ball valve is urged towards closed position by means of the helical compression spring 42', and is forced open by means Aof the rod 36 previously described. The lower portion of the fitting 39 is closed by a plug 43 screwed thereinto and carrying'thev compression spring 42. The supply pipe 12, -similar to that previously described, is provided with a tting 44, which replaces the fitting 13, see Figure 1. The fitting 44 and the fitting 39 are provided with hat faces, which may take any shape. In Figure 4 the face of the fitting 44 is shown. These faces are drawn together, and consequently the

fittings

44 and 39 are joined by means of bolts cr screws 45, preferably a washer 46 of paper, fiber, or similar material being interposed between such faces to insure a gas-tight joint.

A control pipe 47 leads outwardly to the control valve (not shown) from the fitting 39 and communicates with the space above the valve 41 by means of a small duct 48. The interior of the supply pipe 12 communicates with the space below the valve 41 by means of a small duct 49. It is clear, therefore, that when the valve 41 is seated, which would correspond to the condition when the pilot light is lighted, no gas pressure is transmitted to the pipe 47 past the control member, and, consequently, the control valve for the main burner is allowed to operate, as required, in the usual and well know'n manner. However, when the valve 41v is displaced by the thermostatic member, gas pressure is communicated to the pipe 4'? and the main control valve (not shown) is prevented from operating, and, consequently, no gas can pass to the main burner. K.

It isv to be noted that the pipe 50, which connects with the supply pipe 12, is to be connected to the supply'mains ahead of the automatic controlvalve (not shown) for the main burner, in the usual manner. Y It is to be noted particularly that no stuffing box or packing is required for the rod 36, 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 pass- `ing the rod 36 is drawn through the port 51 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 valve 41 shown in Figure 4, and the thermostatic member whereby the effect of the length of the rod 36 may be adjusted to determine the point at which the device will operate.

It willbe seen that both forms of the invention are substantially the same, the differences consisting only in the types'of control members employed.

It is to be .noted particularly that the construction of the apparatus is such that the safety pilot light can be mounted wholly within the casing of the combustion chamber, and that this safety pilot light is not caused to operate by the general temperature or heat within the combustion chamber, 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 substantiallyv foolproof, which is positive in its operation, and which is truly reliable.

Although this invention has been described in considerable detail, it'is to be understcod 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:

1. A pilot light comprising a supporting fuel supply member provided with a fuel nozzle, and a U-tube body portion, one of its main arms being an air inlet and the other main arm being a mixture outlet, said fuel supply member forming the support for said body portion and said fuel nozzle having poor thermal connection with said body portion. y

2. A pilot light comprising a-n integral body portion forming a U-tube, one of its main arms being an air inlet and the other main arm being a mixture outlet, and having a Venturi `throat inspaced from said body portion, saidv supporting means being supported by said fuel supply pipe at a point remote from and below said nozzle and supporting said body portion.

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 pipe4 extending downwardly from the nozzle, and supporting means carried by` and spaced from said body portion, said supat a point remote from and below said nozzle, whereby said body `portion and said supporting means may be bodily lifted fromsaid fuel suppiy pipe.. FRANK A. GAUGER.