US2217785A

US2217785A - Thermoelectrically controlled device

Info

Publication number: US2217785A
Authority: US
Inventors: Paul L Betz; Karrer Sebastian
Original assignee: Consolidated Gas Electric Light and Power Company of Baltimore
Current assignee: Consolidated Gas Electric Light and Power Company of Baltimore
Priority date: 1934-10-16
Filing date: 1937-11-22
Publication date: 1940-10-15
Anticipated expiration: 1957-10-15

Description

Oct. l5, 1940.- P. l.. BETZ Er A1. 2,217,785

THERMOELECTRICALLY CONTROLLED DEVICE Original Filed OCT.. l5, 1934 l 39 39 Kluun Patented Oct; 15,

Paul r.. netz, Baltimore, Ma., and sebastian 'Karren Washington, D. C, assignors to vConsolidated Gas Electric Light and Power Company ot Baltimore, Baltimore, Md., a corporation of Maryland Original application October 16, 1934, Serial No. `748,516. Divided and this application Novemb21' g2, 1937, Serial NQ.'175,918

e claims.

This invention relates to thermoelectrically operated devices, and in particular to thermoelectrically operated safety devices as for gas burners whereby a controlelement as a valve in the gas line will be actuated automatically whenever the. source of heat as a pilot lameto which it is subjected ceases to exist, and where` by, whenever apredetermined condition arises, the device controlled by the thermoelectric current may be actuated independently ofthe 4thermoelectric couple if a dangerous condition arises Vas from excessive temperature or pressure.

In the patent of Sebastian Karrer, No. 2,097,- 838, granted November 2, 1937, for Safety device for gas burners," a safety device for gas burners has been disclosed which permits the use of a relatively small valve thatv can be opened wide, thereby avoiding the use of valve members with only a relatively small lift. with respect to their seat and the consequent need forI a relatively large valve port in order that the desired ilow of gas therethrough can be maintained, which may be removed from the burner .i to any suitable extent and disposed either above or .below as well as in the plane oi the burner '.without interfering with its sensitivity or reliability, and which uses the principle vof a thermoelectric couple and an electr'omagnet energizedby said couple to hold the valve in open position as long as the liame to which the couple is subjected is maintained but efecting a prompt closure' of the valve when the ame goes out. A device embodying these principles but (Cl. 15S-117.1)

I Another; Object of this'invention is to provide" a Safety device for gas burners rwherein all movable parts, except the valve member and its stem, are removed from the passages through which the gas ows.

Another object of this invention is an improved safety device for gas burners, wherein the various parts composing the electromagnet, its armature, its operating mechanism,

etc. may be constructed of simple elements that may be readilystandardized and are inexpensive to manufacture and assemble.l v

Other objects will appear as the description of the invention proceeds.

The invention is capable of receiving a variety. of mechanical expressions, one of which-is shown on the accompanying drawing, but it lis to be expressly understood that the drawing is for pur.-

`posesv of illustration only and is not to be conof improved construction is disclosed in the later l patent of Paul L. Betz and Sebastian- Karrer, No. 2,144,390, granted January 17, 1939, for Safety device for gas burners.

It is an object of this invention to provide means, in combination with a device of any 40 suitable character which is controlled bya thermcelectric couple, for actuating. said device, as by deenergizlng the electromagnet or other means in circuit with said couple, when an undesirable orV dangerous or other predetermined 4condition arises vbut without. altering the constants of the thermocouple circuit or affecting its subsequent'operation in any way.

Another object of this invention is to provide and eilecting the closure of the gas valve, in the.

event that the temperature or pressure in the device rises to a degree that is considered undesirable or'` dangerous. l

strued yas a definition of the limits of the in-n to provide-v vention, reference being had to the appended claims for that purpose.

Referring in detail to the drawing, wherein the same reference characters are employedto designate corresponding parts in vthe several figures,

Fig/1 is a plan view. of mechanism embodying the present invention;

Fig,` 2 is'an axial section through the valve mechanism of Fig. 1 and associated parts;

Fig. 3 is an enlarged detail view of a part'of the device; and

Fig. 4 is a perspective view of a thermocouple element.

The invention in so far as it 'relates to means for deener'gizing a thermoelectrically controlled device can be embodied in a wide variety of constructions for use with a wide variety of devices employing thermoelectric couples, but for sesl purposes of illustration the invention has been shown as embodied in asafety device forv automatically closing a valve ih a gas-line whenever a" flame is extinguished, which safety device embodiesother features of the'inventiuln. As here shown' a main-burnerr Of-a`heaterls indicated at t and maybe of any suitable construction. Said `burner is supplied withh gas through pipe 9 and the gas -supplyfline may be provided, as is more or lesscomino'n, with a valve under the control of a' thermostat of any suitable construction (not shown) ',--iri` order that said valve may be actuatedl andy gas supplied tow .or shut oil from said burner as required 'to maintain the temperature of the water between predetermined limits. Also associated with vsaid burner E is a pilot lil ofany suitablefconstru'ction and supplied with gas through pipe II, which communicates with the main gas conduit on the inlet side of and ahead of the conventional thermostatically operated valve (not shown), although it is to be understood that the safety device to be described may be used with any other suitable form of gas burner, with or without a pilot. ,i 4

In the device shown the flow of'gas to the main burner 8 is to be automatically and promptly stopped by the closure of a suitable valve whenever the pilot flame goes out, and as illustrated, a valve casing I2, of any suitable size, construction and material, and which may be a brass or aluminum casting, is mounted in the main gas line, said casing having an outlet nipple i3 with which the pipe 9 leading to the main Tourner 8 is coupled in any suitable way, as by a screw threaded coupling. 'I'he casing is also provided with an inlet connection I4 that isA threaded or otherwisesuitably formed for connection with a gas inlet pipe (not shown).

The Valve casing I2 is provided with a valve port I5 which may have a yieldable seat and with which cooperates a coned valve member I6 mounted on a tubular valve stem I1, said valve being shown in Figs. 2 and 3 in its open position, wherein it is maintained against spring tension by an electromagnet to be described. In the form shown, the flow of gas through the inlet connection I4 and the valve casing to the pipe 9 and burner 8 is substantially unrestricted by the valve member I6, While at the same time means are provided whereby gas ilow into contact with the operating mechanism is restricted in order to prevent the accumulation of dirt, oil, or other foreign substance which might cause sticking of the armature or otherwise interfere with its intended operation. As illustrated a partition in the form of a plate I8 of any suitable material, which may be resilient or flexible but is not necessarily so, is clamped between the Valve casing I2 and a flange I9 formed on a housing member 20. 'I'he valve stem I1 at its lower end is enlarged in diameter at 2| and the partition I8 is provided at its center with an opening which permits free movement of the enlarged head 2| of the valve stem therethrough. The length of the head 2l is such that when the valve is in the open position shown in the drawing, the enlarged head extends slightly above the upper or rear surface of the partition I 8. Surrounding the valve stem I1 at the upper side of the partition I8 is a flat washer 22 which can move freely with respect to the valve stem I1 and which rests by gravity on the enlarged head 2|. With this construction, the passage of gas from the valve casing to the upper side of the partition I8 is impeded by the restricted path due to the small spacing between the back face of the coned valve member I6 and the partition I8 and omitted. Any other suitable means for restricting or preventing flow of gas through the valve stem opening to the outer side of the partition I8 may4 be employed if preferred.

Supported by the housing member 20 is an electromagnet formed of inner and outer

tubular members

23 and 24 made of a material suitable 'for a magnetic circuit and preferably of high permeability. Extending between said tubular 25 members, at the outer ends thereof, is an annular member 25 which is also of suitable magnetic material and which closes the magnetic gap between the

tubular members

23 and 24. This annular member 25 may if desired be formed integrally with one of the

tubular members

23 or 24 or it may be suitably attached to either or both of said tubular members. At the opposite ends of said tubular members is a second annular member 26 which may be suitably form-ed on or attached to the inner tubular member 23 and which is also formed of the same or similar magnetic material as the

tubular members

23 and 24. The annular member 26, however, does not extend completely from the inner tubular member 23 to the outer tubular member 24, but leaves an annular space forming a gap in the magnetic circuit which may be closed if desired by a ring 21 of suitable nonmagnetic material.

The

tubular members

23 and 24 and the

annular members

25 and 26 enclose an electromagnet coil 28 which is energized as hereinafter described and acts to maintain the valve member I6 in the open position shown in the drawing. I'he Valve stem I1 is tubular and extends freely within the tubular member 23. Within the tubular valve stem is a tubular' plug or sleeve 29 against which bears one end of a coil spring 30, the other end of said spring engaging the lower end of a plug 3I that is inserted within the inner tubular member 23. Spring 30 therefore urges the valve member I6 toward closed position, but the valve is maintained in open position as long as the electromagnet is energized by virtue of a disk-like armature 32 mounted on and suitably secured to the tubular valve stem I 1 and of asuicient diameter to bridge the gap in the magnetic circuit at the ring 21. The construction is therefore suchas to provide a. large surface of engagement between the relatively adjacent pole faces of the electromagnet and the armature 32, assuring against accidental dislodgment of the armature under the shocks and jars to which the device may be subjected under the normal conditions of its service. The outer walls of the electromagnet and the member 20 form a gas tight enclosure for the electromagnet and its armature to prevent escape of such gas as may pass the aperture in the partition I8, or if preferred a separate gas tight housing may surround the electromagnet.

Extending through a bore in the center of the threaded plug 3| and also through the spring 30 and into the tubular valve stem I1 is a slidable wire or rod 33. At its outer end, the rod 33 is suitably formed at 34 to provide a hand grip, and at its inner end said rod is provided with an enlarged head 35 which is of sufiicient diameter-to engage the inner end of the plug 29 within the valve stem when the rod is lifted. The valve I6 can thus be opened manually by pulling on the rod 33, the head 35 engaging the plug 28 and lifting the valve I6 and valve stem I1 against the tension of the spring 30 until the armature 32 comes into contact with the poles of the electromagnet. If the electromagnet is energized, the valve will be maintained in this open position and the rod 33 may then be returned to the position shown in the drawing in order not to interfere with free movement of the valve to its closed position. 'I'his is made possible by the space provided between the end of the valve stem and the plug 29. If the electromagnet is not energized, however, the valve will be returned to closed position by the spring 30 as soon as therod 33 is released.

Thel electromagnet is energized by current from a thermocouple subjected to thepilot flame and 39 which extend toward the pilot |0,`."' Suites-- ably attached to the ends of said. 'arms arethe'V two members 40 and 4l of the tlierxnoelectric ly c l f ammenkof pilot burner lli, so that as long as the pilot is' couple, preferably disposed as`shown entirely within the chamber, definedl by wall 1 whichcontains the controlling source vof -heat I0, said two members preferably having-a suitable name resistant lextension 42 of any suitable metal. Said thermoelectric couple maybe formed .of any x suitable material, such'as chromel-constantan. The

arms

38 and 39 are of such length and ex tend in such a direction as to dispose the extension-42 in the flame of the pilot I0. The members 4|! and 4| may have any suitable length tov maintain the proper temperature differential between the junction of these members at 42 and the opposite ends of said members, in order to obtain the. desired thermoelectric current, but

as rthe material of the members and 4| is ordinarily expensive, these members are preferably made as short as. is consistent with the maintenance of a proper diierence in temperature lbetween the opposite ends thereof. Conyection and radiation as well asy conduction along

arms

38 and 39 are relied on for maintaining-the proper temperature at theA junctions between the members 40 and 4|- and the

arms

38 and 39, which junctions will be also hot because in the same chamber as the hot junction,

but are cooler than the junction at 42 and from the standpoint of the thermoelectric couple -are,`

cold junctions. Any suitable means may be provided for cooling these junctions if desired -in order to increase the temperature differential of the coupling.

If preferred, one of the junctions between the members 40 and 4I and

arms

33 and 39 may be made closer to the junction 42 than the other, or the junctions may be so constructed that one tends to retain its temperature longer than theV other, so that when the pilot flame goes. out one junction will cool before the 'other and `thereby other, as by providing one of the junctions with f sary, particularly'where a spring is used to ini a reversal .of the thermoelectric current will be obtained through the coil ofthe electromagnet to the end tiat the latter maybe completely demagnetized. For example, when a-chro'rnelconstantan thermocouple is used, ,withv

members

38 and 39 of copper, a reversalv of current is obtained when junction 42 is allowed to cool and the temperature is maintained in either or both of the junctions between members 40.` and 4| and

arms

38 and 39. Either or both yof these junctions may be covered with thermal insulation to give the desired cooling rate. 'With other materials than chromel and constanten for" members 40 and 4| it may be desirable to cause one junction tol cool more rapidly than the a radiating iin 39. Reversal of current. through the electromagnet, however, is not` always necestiate movement' of the armature and va/lve member.

The means forclosing the gas valve, as by de energizing the electromagnet and thereby per- 'the thermoelectric current ows.

mitniig'f'ciosore ofthe. valve le By inspringen,

` incase of a-dangerous condition, such asj; an excessive` pressure-orztemperature existing lin the water heater 1 brother device to which the burnenislapplied, is shown in'Fig. 2`,.= Although a means of this kind 'is disclosed herein only in' Y association'with the particular safety device de' jscribed above, it maybe associatedwithlequal facility with anyother thermoelectrically oper-f, `fated* safety device,:as for example the device shown in the aforesaid prior patent of Sebastian Karren No. 2,097,837; or the device disclosed inv the aforesaid prior patent of APaul L. Betz and Sebastian lKarrenNo. 2,144,390, or other similar devices, l.when itis desired lto actuate the same 'independently of the thermocouple if a.- danger,-

kous condition arises,f and asA heretofore pointed-f,

out -i't'may b'ealso Vused-in conjunction with' any` vother 'suitable device controlled zby, a.. thermoelectric couple when it is desired'to shortl circuit the couple 'upon the arisingA of lsome prededer'mined condition. f

Broadly considered, this means as-shown comprises a device responsive to changes either in pressure or temperature, as desired, and effective on increase of pressure or temperature to effect the actuation of the safety device independently of the thermocouple, as by altering the electric circuit of the electromagnet in such away that it becomes ldeenergized and the valve I6 closes. Although in' some instances this may be accomplished by operating a make and break contact device in' the circuit vof the magnet from l the pressure responsive or temperature responsive means, it is preferable where the electro magnet isenergized by a current from 'a thermof -electric couple -to short circuit the electromagnet thereby avoiding the interposition of make and break contacts in the circuit through which For purposes of exempliflcation, a temperature responsive means is shown which comprises a.

circuit shunted' across the leads.36 and 31, said shunt circuit containing a contact adapted to be closed by a suitable thermostatic device herein shown as a bellows thermostatsubjected to the temperature within the water heater. A' casing 43 extends through a suitable opening in the *.wallvof the water heater 1 and into heat conducting relation with theawater in ltheheater, said casing 43 being composed of suitable electrically conductive material. The head orendl wall 44 ofsald casing is electrically connected by means of a lead 45 with one of the leads 31 to the electromagnet. Suitably mounted within the casing 43 is a thermostat 46 of any suitable 1 construction, whichns also composed` of elec" trically conductive ,--material ,and has the-form -l of a bellows iwhichmay be charged with a suitable liquid,- gas or vaporizable liquid, so as'. to

eect a-ipred'etermined-v expansion -.of said therf mostat when the temperature of thewater inthe heaterhas reached a predetermined degree. It

will be seen that thebellows is responsive. to iti- .creases of pressure. 'of the containedz-medium',

whichv is also sensitive to temperature changes, l and the same operation would be obtained-if the` interior ofthe bellows. were placed'in communication with. the pressure .in the heater 1. If desired, thermostatic means ,other than s uch pressureactuateddevices can be employed.

Mounted inthe outer wall or head 44 of the'casing and lsuitably ,insulated therefrom as by. in-

sulating sleeves-or washers 41 is a contact mem- 'i'. ber 43 in line with and adapted to be engaged by a contact member 49 on the end of the thermostat. The contact 48 is suitably connected as by means of a lead 50 with the other lead 36 tothe magnet.

If the temperature within the water heater rises to a predetermined degree, which for example may be chosen below the temperature at which undesirable or dangerous conditions may exist if the heat continues, the thermostat 46 will by expansion close the shunt circuit by engaging the contact 49 with the contact 48. The thermoelectric current, instead of flowing through the electromagnet only, will be divided, one part flowing through the electromagnet and the other part flowing through one of the leads 45 (or 50) and through the casing 43, thermostat 46 and contacts 49 and 48 to the other lead 50 (or 45). The electromagnet thus has its current reduced and is thereby sufficiently deenergized to release armature 32 under the action of spring 30, thereby closing the valve I6. The operation is the same if the bellows 46 is responsive to pressure conditions within the water heater rather than temperature conditions, or if said bellows be replaced by any other suitable type of temperature or pressure responsive device. As will now be apparent, such automatic means for deenergizing an electromagnet or other suitable means in circuit with a thermoelectric couple may also be employed in other devices than safety devices for gas valves, and in fact wherever it is desired to discontinue the active control of such a couple upon the occurrence of predetermined conditions.

In the form shown the safety device responsive to temperatureI or pressure conditions in the water heater insures automatic closing of the valve in case dangerous conditions arise, and this is accomplished in the form shown by shunting or short circuiting the thermoelectric couple without in any way interfering with the constants of the thermoelectric circuit in normal operation. 'I'he safety device may also be positioned at any desired point with respect to the burner and may be located as remote from the heat of the burner as desired, so that the parts may be effectively insulated from the heat generated by the burner and m-ay be composed of materials which might be injured if subjected to the heat of the burner. The electromagnet and its armature as well as all of the movable and operating parts except the valve` and the valve stem are positioned exteriorly of the gas passages, and all of the parts are simple in construction, inexpensive to manufacture and easy to assemble, whereby they may be standardized for production in large quantities and at small expense by the use of relatively unskilled labor. At the same time the device vis certain in operation; the cooperation between the armature and the electromagnet poles is such as to assure against accidental and improper disengagement of the armature; and the fact that the armature and electromagnet poles are removed from the path of the gas assures that deposits of dirt, oil, etc., corrosion or other action arising from contact with the gas will not interfere with the proper and desired operation of the device.

While one embodiment of the invention has been illustrated and described with considerable particularity, it is to be expressly understood that the invention is not to be restricted thereto as the same is capable of receiving a variety of mechanical expressions, some ofwhich will now readily suggest themselves to those skilled in the art, while changes may be made in the details of construction, arrangement, material and proportion of parts, and certain features may be used without other features, without departing from the spirit of the invention. Moreover, 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 sourcesv of heat to prevent the occurrences vof dangerous conditions. It is also to be expressly understood that the means for short circuiting the thermoeiectric couple may be combined with a wide variety of other electrically operated devices, and that any suitable temperature responsive or pressure responsive dev ice and any suitable switch device as well as other suitable means for actuating the safety device upon the occurrence of predetermined conditions may be substituted for the forms illustrated. Reference is thereforeto be had to the claims appended hereto for a definition of the limits of the invention.

This application is a division of our application, Serial No. 748,516, filed October 16, 1934, for improvements in Thermoelectrically controlled devices.

What is claimed is:

1. In a safety device forgas .burners of the self-contained type employing thermoelectrical actuation, a valve casing through which the gas flows to the burner, a valve in said casing, an electromagnet for normally holding said valve in open position and adapted `to be energized by a thermocouple subjected to the heat of a flame at said burner, and safety means for releasing said safety valve by deenergizing said electromagnetic means independently of said thermocouple including a circuit in shunt to said thermocouple, make and break contacts in said shunt circuit, and a device automatically actuated by heat from said burner for closing said contacts to shunt said thermocouple and release said safety valve.

2. In a. safety device for gas burners of the self-contained type employing thermoelectrical actuation, a valve casing through which the gas flows to the burner, a valve in said casing, an electromagnet for normally holding said valve in open position and adapted to be energized by a thermocouple subjected to the heat of a flame at said burner, and safety means for releasing said safety valve by deenergizing said electromagnetic means independently of said thermocouple including a circuit in shunt to said thermocouple, make and break contacts in said circuit, and a pressure actuated device operated by abnormal pressure arising from the heat of said burner for closing said contacts to shunt said thermocouple and release said safetyvalve.

3. In a safety device for gas burners of the self-contained type employing thermoelectrical actuation, a valve casing through which the gas' flows to the burner, a valve in said casing, an electromagnet for normally holding said valve in open position and adapted to be energized by a thermocouple subjected to the heat of a ame at said burner, and safety means for releasing said safety valve by deenergizing said electromagnetic means independently of said thermocouple including a circuit in shunt to said thermocouple, make and break contacts in said circuit, and temperature responsive means operated by abnormal temperature arising. from the heat of said burner for closing said contacts to shunt said thermocouple and release said safety valve.

4. In a safety device for gas burnersof the selfcontained type employing thermoelectric actuation, a control device for the gas, an armature operatively connected to the control device, an electromagnet for normally holding said armature and control device in position to permit flow of gas and adapted to be energized by a thermocouple subjected to. the heat of a gas flame, and

' safety means for deenergizing said armature inlelectromagnet for normally holding said armature and control device in position to permit oW of gas and adapted to be energized by a thermocouple subjected to the heat of a gas flame at said burner, and safety means for deenergizing said armature independently-of said thermocouple, in-

cluding means automatically operated by an abnormal pressure arising frorn the heat of the burner for short circuiting said thermocouple to thereby eiect release of said armature and control device. f

6. In a safety device for gas burners of thel self-contained type employing therrnoelectric actuation, a control device for the gas, an armature operatively connected to the control device, an electromagnet for normally holding said armature and control device in position to permit flow of gas and adapted to be energized by a thermocouple subjected to the heat of a gas flame at said burner, and safety means for deenergizing said armature independently of said thermocouple, including means automatically operated by an excessive temperature arising from the heat of the gas burner for short circuitng said thermocouple to thereby effect release of said armature and control device.

PAUL L. BETZ. Y SEBASTIAN KARRER.