US1995029A - Safety burner - Google Patents

Description

March 19, 1935. J. H. GRAYSON SAFETY BURNER Filed Dec.

. Z 1 1 Z W 3 a 4 \T3 7 z 3 8 Z a J a V M l 9 a 7 1 9 n ax Z M J 1 x j? Patented Mar. 19, 1935 UNITED STATES PATENT OFFICE Application December 30, 1932, Serial No. 649,504

6 Claims.

This invention relates to a new and improved safety burner adapted for use on various gas appliances such as automatic water heaters, radiant heaters, etc.

The embodiment of safety devices on burners has presented serious problems because of the adverse conditions under which they must operate. For example, the use of a sliding rod to actuate the safety valve gave rise to these problems: (a) That of leakage around the rod, given 011 in an unburned condition; any attempt to overcome this by having a tighter flt resulted in sticking. (b) That of lubricant applied to the rod for easier operation and to afford a seal against leakage; it would dry out and result both in leakage and sticking. It is, therefore, the principal object of my invention to provide a safety burner so constructed that the valve actuating rod has a very free fit and the gas leaking around the rod at its lose bearing is conducted with the rest of the gaseous mixture in the mixing chamber and burned at the flame ports of the burner, thereby eliminating the objections mentioned.

Another object of my invention is to provide thepilot burner in the form of a threaded adjustable member so related to the bimetallic 1 thermostat and the main burner that the pilot burner forms a support for the thermostat and serves by its adjustment as the temperature adjusting member. With this arrangement the pilot flame will play directly on the thermostat and light the burner also.

Still another object is to provide a safety shutoff valve which is certain in its operation and does not involve nearly as much restriction in the line as most thermostatic safety valves other wise employed, so that the trouble of excessive pressure drop is avoided.

These and other objects of the invention will appear in the course of the following description,

in which reference is made to the accompanying drawing, wherein- Figure 1 is a central vertical section through a safety burner made in accordance with my invention;

Fig. 2 is a side view, and

'Fig. 3 is a sectional detail on the line 3-3 of Figure 1.

The safety burner of my invention, as stated before, is applicable to various gas appliances, wherever a pilot light lis' 1u'sed to ignite" the gas when it is turned on at intervals under the control of a thermostatic or electro-magnetic' valve.

tinguished in one way or another and when that being of impractical design from the standpoint of the objections enumerated above. Then, too,

the fact that many of these other safety valves were so constructed as to mean a serious increase in the pressure drop, due to the restriction imposed thereby in the line, was frequently the controlling factor in determiningthe unsuitability of the safety valves on certain gas appliances. In the present invention I have, therefore, aimed to incorporate the safety valve in the burner itself in such a way as to keep the cost low enough to be consistent with use on inexpensive gas. appliances and in such a way as to avoid the above mentioned objections and keep well within the pressure drop limit set for most gas appliances.

Referring to the drawing, the numeral 5 designates the main burner generally and 6 designates the pilot burner. The main burner comprises a circular head 7 having two series of flame ports 8 drilled radially therein for communication with the commingling chamber 9 inside the head, and having a mixing tube 10 suitably cast integral with the head and extending from the center of the bottom thereof, as shown. The mixing tube is of c form so as to provide a mixing chamber or passage 11 of the desired length for good mixture of gas and air, but keep the over-all length of the burner down to an absolute minimum. The mixing tube is open to the atmosphere at 12 for intake of air. Aneck 13 is cast integral with the mixing tube in transverse relation to the intake end, and has a gas supply pipe 14 connected therewith. A jet tube 15 extends diametrically through the intake end of the mixing tube and has a close fit in a hole 16 in one wall and is threaded in the hole 1'7 in the opposite wall. This tube opens into the neck 13 for its supply of gas and has a gas discharge jet opening 18 in the wall thereof-directed inwardly relative to the intake end of the mixing tube and approximately on the center line of the passage 11. In that way, as the mixing tube is charged with gas, air will be drawn in through the open intake end 12 of the tube to mix with the gas, so as to produce a Bunsen flame at ports 8. Needless to state, the pilot burner 6 is disposed so as to light the gaseous mixture discharged from the ports 8. In

passing, attention is called to the plates 19 and 20 which have press fits in openings provided therefor in the walls of the head '1 and tube 10, respectively, whereby to close openings formed incidental to the casting of the burner. The tube 15 is entered in the burner through the neck 13 and screwed in place by means of a screw driver entered through the opening for the plate 19 and inserted in the slot 21 provided in the upper end of the tube. The slot is in alignment with the opening 18 so that one can properly locate the opening with respect to the intake end of the mixing tube in assembling. The plug screwed into the opening in the wall of the tube 15 diametrically opposite the opening 18 is removable to permit cleaning the orifice through the intake 12, or to increase the size of said orifice at the time of installation, if desired.

The safety valve provided in accordance with my invention is in the form of a poppet or disc type valve 22 disposed in the neck 13 under the lower end of the tube 15 and arranged to seat on the smooth enlarged lower end 23 of the tube 15 which projects slightly into the neck 13. A bushing 24 is threaded in the neck 13 at a point below the valve 22 and seat 23 and provides a support for the large end of a conical compression spring 25, the smaller end of which encircles the depending hub 26 provided on the valve 22 at the center thereof. The spring 25 normally urges the valve 22 toward its seat, and a rod 2'7 extending lengthwise through the tube 15 and fitting loosely in'the hub 26 of the valve 22- is arranged to unseat the valve under pressure of a bimetallic thermostat 28, as will presently appear. The rod 2'7 has a very free fit in a bearing 29 provided therefor in the tube 15 intermediate the ends thereof and above the gas discharge opening 18. A still freer fit is provided for the rod in the center hole 30 provided in the plate 19. Since the rod has such a free fit in the'bearing 29 there is no need for any lubricant to insure easy working, and, while this will result in some leakage of gas around the rod, there is no objection to that because of the fact that the tube 15 communicates at its upper end with passage 11 and such gas will simply mingle with the gaseous mixture in the passage 11 going to the flame ports 8; no unburned gas can escape. a The location of the tube 15 is, ofcourse, ideal from the standpoint of keeping the bearing 29 cool so that there will be no tendency to corrosion, inasmuch as the air drawn in through the intake 12 comes into direct contact with the tube 15. There is, therefore, no danger whatever of the rod 27 sticking in the bearing 29. Attention is also called to the fact that the loose fit of the valve on the lower end of the rod 2'7 permits the valve to take its own seat so that there will be no danger of leakage by failure ofthe valve to seat all around, and the necessity for very close machine work is avoided. The use of the poppet type valve 22 makes for minimum restriction to the flow of gas; when this valve is open' there is a minimum loss in pressure. It will also appear presently that provision is made for opening the valve 22 far enough to further insure minimum pressure drop.

The bimetallic thermostat 28, which is relied upon to hold the safety valve 22 open by means of its actuating rod 2'7, is arranged to be heated by the pilot burner 6 so as to keep it properly bowed to perform the function stated. The bowing is, of course, due to the fact that the upper half of the strip constituting the thermostat is of a metal having a. greater coeflicient of expansion than the lower half. The strip is disposed radially with respect to the head 7 of the burner 5 and parallel to the top thereof with the inner end engaging the upper end of the rod 27 and with the outer end resting on top of the body 31 of the pilot burner 6. A stud 32 projects from the body 31 and is rotatably received in a hole 33 provided in-the outer end of the strip 28, whereby to hold the strip against endwise movement and maintain the proper relationship between the body 31 and the strip. A forked projection 34 cast integral with the head 7 of the burner 5 has the strip 28 passed through it so that sidewise movement of the strip is prevented and the inner end of the strip kept in proper relation to the rod 27. A

. cross-pin 35 in the fork 34 extends across the top of the strip to serve as an abutment against which the strip will bear as it forces the rod 27 downwardly to open the valve. There are horizontal slots 36 and 37 in the body 31 of the pilot burner on diametrically opposite sides thereof so that one jet will play directly on the strip 28 to heat it and the other jet will be directed outwardly with respect to the head '7 of the burner 5 to light the gaseous mixture discharged from the ports 8. The pilot burner 31 is threaded in a vertical hole 38 provided in the head '7 so as to permit adjusting it and accordingly alter the relationship between the thermostat 28 and the upper end of the rod 27. The adjustment is to insure having the valve 22 held open far enough to avoid undue restriction to gas flow into the burner 5 so long as the pilot burner 6- is lighted and, on the other hand, to insure closing of the valve 22 tightly when the pilot burner 6 is extinguished. A lock nut 39 threaded on the pilot burner serves to hold the pilot burner in adjusted position. A gas supply pipe 40 leading to a point in the gas supply line ahead of the main shut-off cock, or the thermostatic or electro-magnetic valve, as the case may be, is connected to the head 7 so as to discharge into the pilot burner. A nipple 41 is disposed between the end of the pipe 40 and the pilot burner, below primary air openings 42, so as to form a mixer and produce a Bunsen flame on the pilot burner.

The operation is believed to be clear from the above description. If, for any reason .the pilot light is extinguished, while the main burner is shut off by its thermostatically or electro-magnetically controlled valve, the thermostat 28 will cool off and allow the valve 22 to close under the action of its spring 25, so that when the aforementioned valve is subsequently opened there can be no flow of gas into the tube 15, and consequently no danger of gas escaping from the main burner 5. In that way, gas is saved and there is no danger of asphyxiation or explosions. On the other hand, assuming that the pilot burner remains lighted, the valve 22 is kept open wide enough by reason of the bowed or flexed condition of the thermostat 28 so that there is no restriction imposed on the flow of gas into the burner, and consequently no noticeable pressure drop because of the incorporating of the safety valve in the burner. The construction is such that there is no danger of any parts sticking and preventing the closing of the safety valve, and lubrication is made unnecessary. Any gas leaking past the moving part 27 is burned with the rest of the gas delivered to the burner so that no.unbumed gas is allowed to escape.

Referring to Fig. 3, it will be seen that the intake end of the mixing tube 10 is formed with a 1,995,029 3 tending vertically from said valvethrough the crown surface 43 on which a flexible plate valve 44 is seated. The latter is flexed by screws45 entered through opposite ends. and threaded into bosses on the side walls of the mixing tube. The more nearly the valve 44 is forced to full seating the more restriction is imposed upon the intake of air, so that the mixture for the burner can be nicely regulated. The valve also acts as a barrier to keep out dirt and water.

The appended claims have been drawn so as to cover all legitimate modifications and adaptations such as may suggest themselves to those skilled in this art as a result of this disclosure. 7

I claim:

1. In a safety burner, the combination with a main burner, and a pilot burner arranged to ignite the same, of a mixing tube having a cshaped passage with one end discharging into the main burner and the other end open to the atmosphere for intake of air, the intake end having a hollow neck portion extending laterally therefrom a gas supply pipe connected to said neck, a tubular member disposed crosswise in the intake end of said passage and communieating at its one end with the gas supply pipe through said neck and at its other end with the discharge end of said passage, said tubular member having a gas discharge opening provided in the wall thereof intermediate its ends to charge the passage with gas, so as to simultaneously draw in air through the intake end of the passage to mix therewith, a valve in said neck closing off communication between said tubular member and said gas supply pipe, spring means in said neck tending normally to close the valve,

a rod extending from said valve' lengthwisethrough the tubular member and having a free working fit in a bearing provided therefor in said tubular member between the gas discharge opening and that end of said tubular member communicating with the discharge end of the passage, said rod also extending from the top of the burner, and thermostatic means disposed over the top of the burner and so as to be heated by the pilot burner flame and engaging the projecting end of said rod to hold the valve open.

2. In a safety burner, the combination with a main burner, of a mixing tube having a C- shaped passage with the upper end discharging into the burner and the lower end open to the atmosphere for intake of air, a gas supply pipe, a tubular member disposed vertically crosswise .in the intake end of said passage and communicating at its lower end with the gas supply pipe and at its upper end with the discharge end of said passage, a reciprocable valve having spring means tending normally to move the same upwardly against the lower end of the tubular member to close off communication between said tubular member and the gas supply pipe, a rod extubular member and out through the top of the burner, there being a bearing provided for said rod in said tubular member spaced from the lower end thereof wherein said rod has a free working fit, said tubular member having a gas discharge opening provided in the wall thereof below said bearing to charge the mixing tube with gas, so as to simultaneously draw in air through the intake end of the tube to mix therewith, a pilot burner rigid with and in flame propagating relation to the main burner and in laterally spaced relation to the projecting upper end of said rod, and an elongated bimetallic thermostat supported on and heated by the pilot burner at one end and fulcrumed'intermediate its ends on the first burner and having the other end operatively engaging the upper'end of said rod, said thermostat being operable when heated to bow upwardly against said fulcrum and open said valve. I

3. A burner as set forth in claim 2 in which the pilot burner is vertically adjustable relative to the other burner, whereby to cause said valve to be operated at a predetermined temperature.

4. In a safety burner, the combination of a valve seat thereon, a spring biased safety valve movable toward and away from the seat, an actuating rod for said valve guided on said burner for movement toward said valve to open the same, spring means normally tending to close said valve, a. pilot burner rigidly supportedon said burner in a certain spaced relation to the end of said rod and so as to ignite gas issuing from the safety burner, an elongated bimetallic thermostat disposed with one end resting on and heated directly by said pilot burner and the other end engaging the end of said rod, and a fulcrum on said safety burner .and overlying said thermostat intermediate the ends thereof, said thermostat being operable when heated to bow upwardly against said fulcrum and open said valve.

5. A burner as set forth in claim 4 wherein said pilot burner is mounted on the safety burner for endwiseadjustment, whereby to cause the valve to be operated at a predetermined temperature.

6. A burner as set forth in claim 4 wherein said pilot burner has a central upwardly reaching projection rotatably received in a hole in the end of the thermostat, whereby to hold said thermostat against endwise movement and in operative relationship to said pilot burner, and wherein the latter is threaded in the safety burner for endwise adjustment thereof by rotation relative to the safety burner, whereby to cause the valve to be operated at a predetermined temperature.

JOHN H. GRAYSON.

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