US2509896A - Pilot flame control for - Google Patents

Description

Patented May 30, 1950 rinor FLAME CONTROL Foa FUEL commas Woods Stockton Walker, Great Neck, N. Y., as-

signor to Consolidated Edison Company of New York, Inc., New York, N. Y., a corporation of New York Application April 10, 1946, Serial No. 661,028 3 Claims. (Cl. 158-117.1)

This invention relates to apparatus for controlling a pilot flame of a fuel burner, and more particularly to pilot flame control means for a gas furnace.

Heating apparatus such as those employed for heating houses, for example of the gas burning variety, usually are provided with a master gas control valve on the gas supply main for the purpose of shutting oil the gas supply when the use of the furnace is to be discontinued for an appreciable period, such as the summer season. The closing of such a valve, in some types of heating apparatus heretofore employed, shuts off the supply of gas not only to a main burner of the furnace but also to a pilot flame in the furnace. Certain other types of heating apparatus heretofore used have been provided with a separate pilot ,valve control which is not affected by the opening or closing of the master valve because the pilot gas conduit is connected, for example. upstream relative to the master valve.

It is desirable that the users of such apparatus themselves shall beable to turn on and off their furnaces. This involves no substantial diiilculties with regard to the turning oil. of the fuel. However, with respect to turning the fuel on again, diiflculties arise with large numbers of users because of their reluctance or inability to light the pilot flame. In fact, it has been found to be true, especially in large metropolitan areas. that the average furnace user not only requests and expects the fuel or gas company to turn on his fuel whenever it is so desired, but also to turn it off. Thus, in the spring and again in the fall large numbers of furnace users make heavy demands upon fuel companies for such services.

It has been necessary in the past for companies providing fuel, such as gas or oil, to maintain service staffs which devote their time to the turning off and on of the fuel, and to the extinguishing and igniting of pilot flames in furnaces, especially in the spring and fall.

Ihe maintenance of staffs for the above purposes constitutes an added expense which must be passed on to the users of the furnaces. In addition to the expense of this method for starting and discontinuing the operation of furnaces, there is usually the inconvenience of delay between the time a request is made for this service and the time of compliance.

In heating apparatus heretofore employed a disadvantage has existed in that during periods of non-operation of the furnace, such as the summer, the pilot flame is totally extinguished. The temperature within the furnace thus often falls below the dew point and a strong tendency arises for the metal surfaces of the furnace to rust or corrode. This is especially true in damp cellars where furnaces are often located.

Furthermore. apparatus heretofore employed for starting pilot flames have been expensive to manufacture and maintain.

According to the present invention, apparatus is provided for controlling a pilot flame for a furnace which will eliminate the above noted diffleulties.

Various further and more specific objects, features and advantages of the invention will clearly appear from the detailed description given below taken in connection with the accompanying drawing which forms a part of this specification and illustrates, by way of example, preferred arrangements of apparatus for carrying out the invention. The invention consists in such novel combinations of features and apparatus as may be shown and described in connection with the equipment herein disclosed.

In the drawings:

Fig. 1 is a schematic diagram of one form of apparatus for carrying out the invention; and

Fig. 2 is a view partly in section and with parts broken away showing a novel embodiment of a pilot control valve and main fuel control valve.

Referring to the drawings in further detail, simple and inexpensive means are provided which enable a furnace user personally to turn on and off his furnace comprising a main valve and a pilot flame control valve. The user by these means may easily turn down the pilot flame to a small and economical size during extended periods when no heat is required, and he may personally turn the pilot flame to its full operating size at other times without aid from a fuel company or any servicing agency.

The average pilot flame for furnace burners may consume gas at a rate of approximately five cubic feet per hour when of full size. At this rate a pilot flame, which burns during an average summer season, may consume enough gas to involve substantial expense to the user. If the pilot flame is reduced to a point where it is as small as possible, and still constitutes a stable flame, the amount of gas consumed during an average summer season may be reduced by as much as two-thirds.

Generally, according to prior practice, during a summer season the pilot flame is turned oil entirely and the furnace is shut down, the cost for maintaining a full pilot flame being thereby avoided. However, in order to provide the convenience of having heat whenever it is desired I without the delay of waiting for a service agency.v

a reduced pilot flame may be maintained with the present invention at a nominal cost, entirely acceptable to most furnace users.

In the embodiment shown in Fig. 1 means are provided for producing a full pilot flame during normal operation of a gas furnace, and for providing a reduced or small pilot name when it is desired to discontinue the operation of the furnace seasonally or at any other time. The reduced pilot flame which burns continually constitutes the means for lighting the full pilot flame.

A fuel burner, for example, of the gas burning type, of well-known design is provided at IU having a burner element Ii which is in communication by means of a conduit with a suitable source of fuel (not shown). A conventional main shut-oi! or primary control valve may be provided at II. The latter is normally maintained in an open position but may be employed for shutting down the furnace.

A secondary fuel control valve, also of conventional design, may be provided at H and is adapted' by means to be hereinafter described, intermittently to open and close in a. well-known manner in response, for example, to room temperature.

The secondary control valve I4 may be operatively connected in a known manner to, for example, two diflerent heat-responsive means. In the embodiment shown, valve I4 is connected to a room thermostat l5, and to a second thermostat which is variously termed as a furnace thermostat, a pilot flame thermostat, or a safety thermostat. The latter may constitute, for example, a bi-metallic strip which opens or closes a vaive control electric circuit l1, I8 in response to heat applied thereto. Thermostat i6 is adapted to be actuated by a predetermined minimum amount of heat. In a manner to appear hereinafter it is actuable by said full pilot flame but not by the reduced flame. Said circuit is connected to a suitable source of electric energy (not shown) by means of leads L1, L2. The above-mentioned operative connection between valve l4 and the thermostats I! and It may comprise the circuit l1, l8, and a solenoid I! in the circuit which, when energized, is capable of moving a suitable valve control arm 20 against the action of a spring 2| to open valve H.

A pilot flame conduit or tube 22 is provided having a nozzle or burner 23 which is preferably adjacent the furnace thermostat IS. The pilot flame tube is in communication with conduit l2 at a point 22' which is disposed upstream relative to the valve 13.

' Novel means are provided for controlling said pilot flame, which means are extremely simple of operation and are adapted for personal manual operability by thefurnace user, whereby a, full flame may be produced and controlled during normal operation of the furnace, and a reduced pilot flame of economical size may be easily obtained and maintained during periods of seasonal nonuse of the furnace. In the form shown in Fig. l,- the novel means comprise a pilot control valve 24, around which a by-pass 25 is provided. Fluid flow through the latter preferably is adjustable, for example, by a suitable piston type valve capable of fine adjustment by angular movement of a threaded screw. Such adjusting means maybe located at 26. A small amount of fuel thus'may flow to the nozzle 23 at all times even though the main pilot control valve 20 is closed. This small amount of m1 is suflicient to provide the reduced pilot flame above discussed.

In operation, when the furnace is in normal use both main valve II and pilot valve 2. are in open positions. The pilot flame at 22 is at its full size. The heat from the full pilot flame is suflicient to actuate the heat-responsive means It thereby closing at that point the electric circuit II, It. The flow of fuel through conduit i2 thus is controllable in a well-known manner by the thermostat i i in cooperation with valve means H and the solenoid It. When it is desired to suspend the operation of the furnace for a considerable period, such as the summer season. the valve I3 preferably first is closed. The pilot flame at 23 is still at its full size. Circuit il, II is. therefore, closed at the thermostat I and valve I4 is operable in its usual manner by the thermostat it even though no gas may flow to the furnace.

The pilotcontrol valve 24 is next closed. The

main flow of fuel to the pilot flame consequentLv is shut off. However, a sufficient quantity of fuel flows via the by-pass 25 to maintain a small but stable flame at the nozzle 22. The smallflame is not of sufficient intensity to actuate heat-responsive means It. Consequently, the circuit II, II is promptly opened. During the period when only the small flame burns it is, therefore, impossible for the solenoid it to be energized. Consequently the control arm 20 of valve I4 is withdrawn to a closed position by the action of spring 2|, and the room thermostat II is ineffective to control the furnace. During this period the heat from the reduced pilot flame is sufficient to maintain a temperature within the furnace in excess of the dew point and thus serious corrosion may be avoided.

When it is desired to put the furnace back in operation, for example, at the end of the summer season, the above procedure is reversed. First. the pilot valve 24 is opened, thereby producing a full pilot flame, the intensity of which actuates the thermostat l6 and renders operable the valve control solenoid I9 and the valve ll. Next, the

main valve i3 is opened and the furnace now is able to operate in its normal manner in res to the thermostat i5.

If desired, a suitable mechanical linkage or interlock of known form, between the main control valve and the pilot flame valve may be providedin order to prevent shutting the pilot valve until the main valve has been closed, and to prevent opening the latter until after the pilot valve opened.

In order to simplify the operation of turning on and oil the gas furnace and to provide automatically for the increase or reduction in the pilot flame substantially simultaneously with the so time of turning on or of! respectively of the main gas supply, novel integral main and pilot control means may be provided according to the embodiment shown in Fig. 2 which comprises a valve 21 having a housing 28, an inlet 28a, and an outlet so 2817. A rotatable valve member 29 is provided in said housing having a main channel 3| therethrough and a pilot fuel channel ll. The latter is preferably substantially perpendicular to channel 30 and is in communication with pilot conduit 22 by means of a channel 32 which, for example, is in direct connection with a pilot flame by-pass channel 33. Channel 22, however-[Indy be in direct connection with conduit 22. The extremity of channel II which is in register with 7 channel 32 in Fig. 2 is closed off entirely by housing 26 when rotatable valve member 29 is angularly shifted an amount sufficient to move said extremity out of register with channel 32.

By-pass channel 33 and channel 32 are preferably formed in the housing 28. Channel 33 has an inlet at 33a, and an outlet 33b. By-pass inlet 33a is in communication with valve inlet 28a and is upstream relative to rotatable valve member 23. Conduit 22 may be connected at 33b.

Suitable means are provided for manually rotating the valve member 29 comprising a handle 34 which is preferably fixed directly to said valve member.

In order to make fine adjustments of fuel fiow through the by-pass channel 33, a suitable bypass valve of, for example, the piston type is provided at 35 which may be adjusted by angular movement of threaded member 35a.

In operation, in the angular position of the rotatable valve member 29 shown in Fig. 2, the fuel is able to flow freely from inlet 28a through the main channel 30 of valve member 29 to outlet 23b and thence to the furnace via conduit 12. Fuel for the pilot flame reaches conduit 22 not only through the by-pass 33 but also through the channels 3| and 32. Flow through the channels If and 32 is, of course, the main source of pilot flame fuel. A. full pilot flame is thus sustained. If it is desired to shut off the furnace, for example, for the summer, the handle 34 is angularly shifted through 90 degrees in a clockwise direction. Thus in a single motion, and substantially simultaneously, the main fuel flow to the furnace and to the pilot flame are stopped. Only a restricted amount of gas may now flow to the pilot flame through by-pass 33 in a quantity sufficient to produce a small but stable flame. The intensity of the latter is, as above mentioned, insufficient to actuate the safety thermostat I6 which promptly cools and opens the circuit l1, I3 thus causing the secondary valve l4 to shut off the main gas supply to the burner. In this condition both the primary and secondary gas control valves (21 and II respectively) are closed thus providing additional safety against gas leakage into the furnace or accidental operation thereof.

A reverse procedure is followedfor starting the furnace in operation. The handle 34 is reversed in movement to the position as shown in Fig. 2. The full pilot flame is thus immediately produced without the necessity for ignition by some separate means. In case the full pilot flame fails to come on for any reason, thermostat switch l6 will remain open and valve It will remain closed.

The novel pilot flame control has been described in connection with a gas furnace. However, it may be employed in any type of furnace burning a fuel which is adapted for ignition by a pilot light, for example, an oil burning furnace.

While the invention has been described with respect to certain preferred examples which have given satisfactory results, it will be understood by those skflled in the art after understanding the invention that various changes and modifications may be made without departing from the spirit and scope of the invention, and it is intended, therefore, in the appended claims, to cover all such changes and modifications.

' What is claimed as new and desired to be socured by Letters Patent is:

1. In apparatus of the class described, a min gas conduit, a gas burner, a primary control valve in said conduit, a secondary control valve in said conduit, a pilot fuel conduit operatively associated with said burner, a pilot flame burner connected to said pilot conduit, a pilot flame control valve in said pilot fuel conduit for controlling a full pilot flame, by-pass means around said pilot flame control valve permitting a restricted flow of gas for sustaining a small pilot flame, heatresponsive means adjacent said pilot flame burn er, and electrical means operatively connected to said heat responsive means and to said secondary control valve for controlling the latter by said heat-responsive means, the latter being actuatable by said full pilot flame only.

2. Apparatus of the class described, comprising a fuel burner, a main fuel conduit to the burner, fuel flow control means in said conduit, a pilot conduit for feeding fuel to a pilot flame for said burner, a pilot flame burner connected to said pilot conduit, heat-responsive means operatively associated with said pilot flame burner and said fuel flow control means, the heat responsive means being operatively associated with said fuel fiow control means by electrical means, and

. mechanism in the pilot conduit for adjusting the pilot flame to a full size and to a small size, said heat-responsive means being actuatable by a pilot flame of full size only.

3. Apparatus of the class described, comprising a fuel burner; a main fuel conduit connected to said burner; primary fuel control means for said conduit; secondary fuel control means for said conduit; a plurality of heat-responsive elements; electrical means for operatively interconnecting said elements and said secondary fuel control means; a pilot tube having a pilot burner at which a pilot flame can burn for said first-mentioned burner. said pilot burner being positioned adjacent to one of said heat-responsive elements, the latter being aotuatable by a flame at said pilot burner; valve means in the pilot tube, said valve means when open permitting a full pilot flame fuel flow; and by-pass conduit means around said valve means permitting a continuous small pilot flame fuel flow, said heat-responsive element adjacent said pilot burner being actuatable by a full pilot flame only.

WOODS STOCKTON WALKER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS.

Number Name Date 1,036,479 Flamm Aug. 20, 1912 1,510,991 Holt Oct. 7, 1924 1,666,243 Manning Apr. 17, 1928 1,842,126 Snow Jan. 19, 1932 1,914,805 Hoegger June 20, 1933 1,943,045 TePas Jan. 9, 1934 1,946,116 Sinton et al. Feb. 1934 2,016,577 Pearson Oct. 1, 1935 2,094,284 TePas Sept. 28, 1937 2,248,737 Beam July 8, 1941 2,286,156 Petersen June 9, 1942 2,357,609 Ray Sept. 5, 1944 2,373,326 Miller Apr. 10, 1945 FOREIGN PATENTS Number Country Date 649,816 Sept. 9, 1937

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