US2097838A

US2097838A - safety device fob gas burners

Info

Publication number: US2097838A
Authority: US
Publication date: 1937-11-02
Anticipated expiration: 1954-11-02

Description

J llululvllvv Search Room FIPYQnQ Nov. 2, 1937. s. KARRER l SAFETY DEVICE FOR GAS BURNERS Filed June 50, 1931 Patented Nov. 2, 1937 UNITED STATES PATENT OFFICE SAFETY DEVICE FOR GAS BURNERS Sebastian Karrer, Washington, D. C., assignor to Consolidated Gas Electric Light and Power Company, Baltimore, Md., a corporation of Maryland Application June 30, 1931, serial No. 547,977

4 Claims.

for a relatively large Valve port in order that the l desired flow of gas therethrough can be maintained.

v Another object of this invention is to" provide a device of the type characterized which may be removed'from a burner to any desired extent, and which can be disposed above or below as Well as in the plane of the burner without interfering with the sensitivi'tyor` reliability of the device,r '.Angther object'of this invention is to provide a device' of the type characterized which is made of materials which are noncorrosive. f Another object of this invention is to provide a device of the type characterized wherein the valveA and Vits associated mechanism may vbe disposed away from the zone of high temperature around the burner. l

Another object of this'invntion'is'to provide a device of the typeV characterized which is so constructed as to assure a complete and tight closure of thev main valve whenever the device -is actuated.

' Another object of this invention is to provide a device of the type characterized whichis so constructed that the pilot must be relighted manually by following a procedure which guards against dangerous conditions and accidents.

Another object of this invention is to provide a device of the type characterized whichA uses the principle of a thermoelectric couple and an electromagnet for maintaining a valve in open position as long as the burner to which the couple is subjected is burning, but which will effect a prompt closure of the valve when the flame goes out.

Another object of this invention is to provide a device of the type characterized which is simple and compact in construction, inexpensive to build and install, and durable and reliable in operation. Other objects will appear as the description of the invention proceeds.

The invention is capable of receiving a variety of mechanical expressions, two of which are shown on the accompanying drawing, but it is to be expressly understood that the drawing is for purposes of illustration only and is not to be construed as a definition of the limits of the invention, reference be? .g had to the appended claims for that purpose.

Referring in detail to the drawing wherein like reference characters are employed todesignate corresponding parts inthe several figures,

Fig. 1 is an elevation, partly in section, of one embodiment of the invention;

Fig. 2 isa plan view; and

Fig. 3 is a fragmentary section oflanother embodiment.

The invention can be embodied in a Wide variety of constructions for use with a wide variety of devices employing gas burners, but for purposes of illustration the invention has been shown, more or less schematically, as embodied i in a device for automatically closing a valve in the gas line leading to the burner of a hot water heater whenever the pilot of said heater goes out. The heater is diagrammatically indicated at 8 and'may have a main burner of any suitable construction supplied with gasV through a suitable pipe I1 and provided with 'any 'suitable valve undeifthe gritrol vof athermostatwto be opened and closed in accordance with the temperature of the Water within the tank. Associated with said burneras i's usual is a pilot 9fwhich is intended t reman'lighted and which may also be of any suitable construction;

In aocordaiice with the present invention the gas owi'ng" tofthe'main burner and pilot passes through a chamber II which may be provided in a casing I2 of any suitable size, construction and material, such as a brass or aluminum casting,

and disposed at any suitable distance from the v burner, either in the plane thereof or above or below the same. As shown, said casing has suitable inlet and outlet pipes I3 and I4 on opposite sides of a valve seat I5 surrounding a valve port I6. The valve seat I5 may be formed in or attached to the casing I2 in any suitable way but is preferablyl made as an aluminum thimble having an upstanding rim, which may be tapered if desired, for engaging the valve member to be described. A

Closing the chamber II, and shown as telescopically received Within the upper end of the casing I2, is an electromagnet I8 of any suitable construction. As shown it is formed of inner and outer tubular members 28 and 2I made of material ,suitable for a magnetic circuit and preferably made of material of high permeability. Interposed between said tubular members 20 and 2I at opposite extremities thereof, is a collar 22 of brass or other suitable non-magnetic material and a collar 23 of magnetic material inserted into the annular space between the tubular members 2U and 2| and having an intimate contact therewith. The ends of tubular members 20 and 2l and the interposed collar 22 exposed to the chamber II may be tinned or otherwise coated to protect the same against corrosion. Surroundingr the in ner tubular mem- Mounted within the chamber II is a combined valve member and armature 25, shown as in the form of a disk having on its underface av coneshaped projection 25 designed to enter and'snl'lgly Contact the valve seat I5 heretofore described. Said combined armature and valve member are preferably made of a material having high permeability so that it will operate inthe manner hereinafter described. Projecting from `said member 25 is a stem 27 which is telescopically received within the inner tubular member 20 and a inst which reacts a coil spring 29 that urges armature 25 away from the end of the electromagnet. If preferred, although such is not necessary, means may be provided for adjusting the tension of said spring, and in the form shown an adjusting screw 3 0 is threaded into the outer end of the tubular member '20 and reacts against the end of the coil spring 29.

The leads 2li from the coil of the electromagnet project a considerable distance toward the pilot 9 and may" be bent or curved to" any de sired extent. Said leads are connected at 32 and 33 to the

elements

34 and 35 of a thermoelectric couple formed'of any suitable material such as Chromel-,Constantin or Chromel-Alumel, the junction 36 of whichjterminalsgis disposed in or slightly above the flameof the'pilot. The

junctions

32 and 33 may vbe atany suitable point to maintain theiproper tempera'tureA diierential between the lsame and the junction 36 in order to obtain the desired'thermoelectric currents, but as the material of the

terminals

34, 35 is ordinarily more expensive thanthat of the leads 24, said

junctions

32 and 33 are preferably made as close to the junction 3S as is consistent with the maintenance of a proper diie'rence in temperature therebetween. Reliance may be placed either upon convection or radiationV for maintaining the proper temperature differential between said junctions.

If preferred one of

said junctions

32 and 33 may bn made closer to the'junction 3S than the other, or it may be so constructed'that it4 will radiate heat less freely or cool more slowly so that it tends to retain its temperature longer than junction 36, sothat when the pilot light goes out junction 36 will cool before the junction last referred to, and thereby a'reversal of the thermoelectric current will be obtained through the coil or" the electromagnet tothe end that said electromagnet may be completely deragnetized. Such a construction, however, is ordinarily unnecessary where a spring is provided, normally urging the armature away from the end of the electromagnet, as shown.

In order to reset the combined valve and armature after it has closed the valve port I6, the end oi the casing`l2 is provided with an extension 3l in the closed end'38 of which reciprocates a stem 4D provided at its outer end with a iiange 4I. Interposed between the ange 4I and the end of the extension 31 is a light'coil spring 52 which tends to hold the stem in its outermost position as limited by any suitable stop 13 provided on said stern. If desired, the spring may be replaced by a rubber diaphragm which wiil not only Aurge the stem to its outermost position but also seal the opening around the stem against the escape of gas. Preferably Search Room the end of the projection IS'I is also threaded and an interiorly threaded nipple 4G is provided for enclosing the stem and spring of the manual device just described and forming a gas-tight seal with the extension 3T. By pressing on the flange 4I the stem is projected into the chamber II to disengage the valve member 25 from its seat I5 and lift it into contact with the end of the `electromagnet I8.

In operation, and assuming that the pilot is lighted, the flame at the junction 36 maintains a thermoelectric current through the electromagnet and the armature 25 is held against the tensionI of the spring 29 against the end of the electromagnet. This condition is maintained as long as the pilot is lighted, and gas can flow freely through the wide open port I6 to the pilot and thermostatic valve of the main burner.

If the pilot light goes out, the thermoelectric current through the electromagnet I8 ceases and the valve member 25 moves to close the valve seat I5 under the pressure of the spring 29, aided by gravity if the device is installed vertically, the tension of the spring being suiicient to detach the armature from the electromagnet notwithstanding any residual magnetism therein. Although the device can be installed horizontally it is preferred to install it vertically, and the valve member in falling acquires considerable kinetic energy, so that the valve projection 26 therefore engages the valve seat I5 with' sucient force to-slightlydistort the same if necessary and assure a tight closure throughout the circumference of the valve member. the valve isitightlyeclosed against leakage;

Before the pilotr'can be relighted it is necessary to remove the nipple 44, when used, and

then press outwardly on' the flange 4I to disengage, through the stem '40, the valve member 25 from its seat and lift it into engagement with the end of the electromagnet. During suchA lifting. movement by the stem 40, as well as during the closing movement when the electromagnet hasbecomedemagnetized, the valve member is guided at its center by the stem 21 and may also be guided at its periphery by the interior of -the casing I2. The pilot can then be relighted, but the stem 40 must be held in the position to retain the armature 25 against the electromagnet I8 for a suiicient period to assure that the thermoelectric current has energized the electromagnet. The device is thereby reconditioned, and upon release of the flange 4I the spring 42 will restore it to its outermost position, out of the way of the valve member 25 when the device is next actuated. Thereafter' the nipple can be restored and makes a gastight joint with lthe threaded boss, assuring against leakage of gas from the casting.

In the embodiment of Fig. 3 the parts correspond in construction and function with the Aparts heretofore described but in this embodiment the stem 40- for restoring the armature to the end of the electromagnet extends out- `wardly through the electromagnet and the center opening of a bored adjusting screw 30', so that it must be pulled outwardly by the ange 4I when the armature is to be restored to the end of the electromagnet. The nipple 44 may now be -attached to the threaded end of the adjusting screw 30.

It will therefore be perceived that the safety device of the present invention may be removed vfrom the burner to ai; `desired extent, where it is remote from the heat of the burner, and

also away from the corroding influences of the gases. Furthermore, the safety device can be disposed in any suitable location with respect to the burner, and need not be aligned with the same in the same plane, but can be either above or below the plane of the burner. Also the present invention enables the use of a relatively small valve, because the valve' can be fully opened, and hence the need of a large diameter conduit, Where the valve member can open but a small fraction of an inch in order to afford the requisite flow of gas, has been entirely avoided.

,Owing to the fact that the safety device is remote from the heated zone around the burner, and hence effectively insulated from the heat generated'thereby, it is also possible to make the valve seat and other parts of aluminum which, experience has demonstrated, is little subject to corrosion but which cannot be used satisfactorily when the metal is likely to be subjected to relatively high temperatures. By making the valve seat of aluminum, the seat can be slightly deformed under the kinetic energy of the valve member, so as to ensure a tight engagement between the valve seat and member throughout 360 of contact.

It is to be understood that the valve member may be disposed at any suitable distance from the valve seat so that the valve member will develop the desired kinetic energy for assuring the desired engagement between the valve member and its seat. If the device is installed vertically, this kinetic energy in turn will depend to some extent upon the Weight of the valve member as Well as its distance from the valve seat. The valve member should not be of sucient weight to be jarred loose from the electromagnet lwhen'in operating condition, and yet it is desirable that it have appreciable Weight so that it may develop considerable kinetic energy when falling through a relatively short distance, to the end that the device may be reasonably compact.

It will furthermore be perceived that the present invention assures that the pilot can be relighted only by the pursuance of a definite procedure by an operator so that the operator is fully cognizant of the fact that the pilot has gone out and can determine the cause. At the same time the safety device is of a relatively simple construction, is composed of relativelyv few parts which can be easily manufactured and assembled, is easy of installation, and working on the principle of a thermoelectric couple, it is both durable and reliable in operation.

While two embodiments of the invention have been illustrated on the drawing and described with considerable particularity, it is to be expressly understood that the invention is not restricted to the embodiments illustrated, as the same is capable of a variety of embodiments some of which will now readily suggest themselves to those skilled in the art, While changes may be made in the details of construction, ar-

, rangement and proportion of parts and certain features used without other features, without departing from the spirit of the invention. Furthermore, while the invention has been illustrated and described as employed in conjunction With a pilot light, it will be apparent that the invention can also be used as a safety device in connection with other devices, as for example the thermoelectric couple could be subjected to the heat of a l,main burner where it is desired that the gas valve be closed whenever the main burner goes out. Other uses for the invention will also suggest themselves to those skilled in the art. Reference is therefore to be had to the appended claims for a definition of the rlimits of the invention. .l

What is claimed is:

1. In a device of the character described, in combination with an electromagnet having an armature connected to a. controlling member, a thermocouple adapted to be subjected to the heat of a flame and electrically connected with said electromagnet whereby said armature and member are held in operating position by the thermoelectric current iiowing through said electromagnet as long as said thermocouple is heated by said flame but on extinguishment of said flame said controlling member is moved by the release of said armature by said electromagnet, and means in said thermoelectric circuit for assuring release of said armature by said electromagnet by demagnetization of said electromagnet and including a junction of said thermocouple adapted upon extinguishment of the flame to cool more slowly than the junction normally subjected to the flame.

2. In a device of the character described, in combination with an electromagnet having an armature connected to a controlling member, a thermocouple adapted to be subjected to the heat of a llame and electrically connected with said electromagnet, said thermocouple adapted to generate current to energize said electromagnet and hold said armature and member in operating position as long as said thermocouple is heated by said flame but to release said armature and member for movement to asafety position upon extinguishment of said flame, and means in said circuit to effect a reversal of current therein and assure demagnetization of said electromagnet on extinguishment of said ame comprising a junction of said thermocouple adapted to cool more slowly than the junction submitted to said flame.

3. In a device of the character described, in combination with an electromagnet having an armature connected to a controlling member and adapted when energized to hold said member in operating position and when deenergized to release said member for movement to a safety position, a thermocouple adapted to be subjected to a flame, an electric circuit including said thermocouple and electromagnet, and means in said circuit for assuring demagnetization of said electromagnet and release of said armature and member when said flame is extinguished and comprising means for effecting a reversal of current through said electromagnet.

4. In a safety device of the character described, in combination with an electromagnet having an armature connected to a controlling member and adapted when energized to hold said member in operating position and when deenergized to release said member for movement to a safety posi.- tion, a thermocouple adapted to be subjected to a ame, an electric circuit including said thermocouple and electromagnet, and means in said circuit for assuring demagnetization of said electromagnet and release of said armature and member upon extinguishment of said flame comprising a junction of said couple which retains heat longer than the junction subjected to the flame to cause a reversal of current.

SEBASTIAN KARRER.