US2383401A - Thermostat, safety pilot, and limit control - Google Patents

Description

Aug. 21, 1945. H. A. MANTZ 2,383,401 I THERMOSTAT, SAFETY PILOT AND LIMIT CONTROL Filed Jan. 29, 1943 2 Sheets-Sheet l Patented Aug. 21, 1945 THERMOSTAT, SAFETY PILOT, AND LIMIT CONTROL Harold A. Mantz, Milwaukee, Wis., asslgnor to Milwaukee Gas Specialty Company, Milwaukee, Wis., a corporation of Wisco Application January 29, 1943, Serial Nordldfids 16 Claims.

This invention relates to control systems and has to do more particularly with a system for heating a body of fluid by means of a burner and for controlling supply of fuel to the burner responsive to temperature variations of the fluid body being heated, while assuring that fuel supplied to the burner, after extinguishment thereof, will be ignited.

My invention is directed to a system comprising a main burner having associated igniting means, and operating means effective for shutting oh the supply of fuel to the burner when the igniting means is rendered inoperable or when the temperature of the fluid being heated exceeds a predetermined maximum, the operating means being also responsive to the temperature of the fluid for shutting off the supply of fuel when the fluid is at a desired maximum temperature and reestablishing the supply of fuel when the fluid is at a desired minimum temperature, when the igniting means is operable. More specifically, I provide a main fuel supply control valve the opening and closing of which is controlled, under normal operating conditions, by the temperature of the fluid body, and means assuring closing of the valve and maintaining it closed upon failure of a pilot burner associated with the main burner, or when the temperature, or the fluid exceeds the desired maximum, the latter means comprising an electromagnet energized by the heat of the pilot burner and reset means for setting the parts for normal operation.

I have illustrated the conrtol system of my invention as applied to a water heater, by way of example, but it is to be understood that my invention, in its broader aspects, is capable of many other applications and may be used for controlling the temperature of water or any other liquid or fluid within an enclosed space or container. Further objects and advantages 'of my invention will appear from the detail description.

In the drawings:

Figure 1 is a side view, partly broken away and in section, oi a hot water boiler and heater control means therefor embodying my invention;.

Figure 2 is a central vertical sectional view, on an enlarged scale, of the control means of my invention, certain parts being broken away and certain parts being shown in elevation, with the P rts in the positions they occupy when the control valve closing member is in its released or operable position; and

Fi ure 3 is a semi-diagrammatic sectional view on the order of Figure 2'but with the control valve in open position and the closing member'for that valve in its attracted or inoperable position.

The hot water tank 5 may be of any suitable known construction and is provided, a suitable distance from its lower end, with a domed bottom wall 5 beneath which is disposed a main gas burnerl, within a chamber 8 defined by the depending lower slzirt portion 9 of the tank. Cold water is supplied to tank 5 through a down pipe it and hot water is withdrawn from the tank through a pipe M. The burner i may be of any suitable known type and comprises a conduit l2 flared at its lower end to provide a mixing chamher it having a plate it provided with air admission openings and adjustable" for regulating the amount of air admitted to chamber it. Gas is supplied to mixing chamber it through a nipple it suitably mounted on the upturned end of a gas supply pipe it passing through an opening in skirt 9.

A valve body it, shaped as shown, is mounted on tank 5, by means of an exteriorly threaded nipple 2i screwing through a boss 22 of the tank. Valve body Ell is separated interiorly into an inlet chamber 23 and an outlet chamber 26, by a partition it having a valve opening 25 therethrough surrounded at the inlet chamber side with a raised valve seat element 27?. Bottom wall it of valve body 2t is suitably bored and tapped for reception 01 the upper end of pipe it screwed thereinto and opening into outlet chamber 2 3, and for reception of a second gas supply pipe ill screwing at its upper end into wall 28 and opening into inlet chamber 23. Pipe 29 is connected to a suitable source of supply of fuel gas, as will be understood, and is provided with a normally open shutoff cook 30 of known type.

Opening 2@ is controlled by a valve comprising a cupped valve disc at at the inner face of which is mounted an angular facing member 32, of leather or other suitable material, confined between disc ti and a retaining washer 33 fitting about the reduced innerportion of a boss 34 projecting from the inner face of disc 3| and peened over at its inner end at MA as shown. A relatively large cylindrical boss 35, extending from the outer face of valve disc 35, has a sliding fit in a cylindrical valve stop and closure member 36 provided, at its outer end, with a reduced outwardly tapering extension 31. This extension 31 is flanged inward at its outer end and there fits about the inner end portion of an operating stem 38 having, adjacent its inner end, a circumferential groove 38 which receives a resilient U -shaped retaining member 40 of known type. The member 38 is thus attached to the inner end of stem 38 for outward movement with the latter. A stop plug 31a, threaded into the inner end of extension 31, assures inward movement of member 36 with stem 38 upon inward movement of the latter.

Stem 38 is slidable through an outwardly extending packing gland 42 of a cup-shaped inner section 43 of an electromagnet housing 44 having also an outer cylindrical section 45. The inner end portion of section 45 is offset outwardly slightly and has a push fit over the outwardly offset outer end portion of section 43. Thesection 45 is provided at its inner end with an outwardly extending circumferential flange 46 clamped between the outer end of an exteriorly threaded neck 41 projecting from the front of body 20, in which neck 41 section 43 fits closely, and a flanged nut 48 screwing on the neck, with an intervening sealing gasket 49. Gland 42 receives packing material 58 compressed by a washer slidable on stem 38 and urged outward therealong by a coil compression spring 52 mounted about extension 31 of member 36 and stem 38, confined between the outer end of member 36 and washer 5|. The housing 44 is thus effectively sealed off from inlet chamber 23 so as to guard the parts within housing 44 from the deleterious effects of the gas or other fluid in that chamber.

An armature 53 of suitable magnetic material is secured ina cradle 54 mounted on the outer end of stem 38, between two U-shaped retaining members 55, of known type, engaging in corresponding circumferential grooves 56 in stem 38. This mounting of the cradle 54 is a loose mounting permitting, slight universal movement thereof in order that the armature may seat accurately on the pole ends of the frame of an associated electromagnet. A substantially U-shaped electromagnet frame 51, of suitable magnetic material, is supported within housing 44, by a bracket 58 secured to frame 51 and to the outer end of housing 45 by connector means, as will be explained presently.

The connector means is generally similar to the means disclosed in the Alfery Patent No. 2,276,909. It comprises an exteriorly threaded terminal bushing 59 extending through a corresponding opening in the outer end wall of housing 44 and provided at its inner end with an interior shoulder 68. A terminal member 6|, mounted in bushing 59, is provided at its inner end with a reduced stud 62 extending through the inner end of bushing 59 and through the outer portion of bracket 58, from which and bushing 59 member 6| is insulated by a shell 63 of insulating material. A washer 64 of insulating material is disposed about stud 62, at the inner face of bracket 58, and one terminal lead 65 of a coil 66, mounted about one leg of frame 51, is extended between washer 64 and a, metal washer 61 disposed about stud 62 adjacent the inner end thereof. The other terminal lead 68 of coil 66 is grounded to bracket 58, the outer portion of which seats against the inner end of bushing 59, and a sealing gasket 69 is disposed about the inner end portion of bushing 59 at the outer face of bracket 58. The inner end of stud 62 is peened over at 10, clamping tightly together the parts between the inner end of stud 62 and the inner end of bushing 59 in a manner effective for establishing good electrical connection between lead 65 and stud 62 and between bracket 58 and bushing 59, while also securing the stud 62 to the bushing 59. A nut 1| is screwed on bushing 59 in contact with the outer end wall of housing 44, with the adjacent portion of that wall clamped between nut 1| and gasket 69, so that the connector assembly is secured to housing 44 with gasket 69 forming a fluid tight seal about the bushing 59.

' A thermocouple 12 is disposed adjacent the main burner 1 in association with a pilot burner 13 for igniting fuel issuing from burner 1. The thermocouple may be of any suitable known type, but preferably is similar to that disclosed in the Leins Patent No. 2,126,564. It comprises a hot junction 14 disposed to be heated by the flame of the pilot burner, an external metal tube 16 constituting a lead, connected at one end to the external element of the thermocouple, and an internal lead 16 connected at one end to the internal element of the thermocouple and extending through and insulated from tube 15. A metal thimble 11, flanged at its inner end, is secured upon the other end of tube 15 with its outer end portion within the correspondingly formed outer end portion of a sleeve 18 through the outer end of which thimble 11 extends. A conical tip contact member 19 is secured upon the other end of lead 16 in concentric spaced relation to sleeve 18, with a washer 80 of insulating material fitting about lead 16 between the base of thimble 11 and the base of tip member 19, this washer also fitting tightly within sleeve 18 and serving to hold tip member 19'spaced therefrom. Sleeve 18 is threaded interiorly at its inner portion and when it is screwed on bushing 59 clamps stud 6| and tip member 19 together, with tip member 19 seating tightly in a corresponding recess in the outer end of stud 6|, sleeve 18 then also serving to clamp thimble 11 to bushing 59 and to establish good electrical connection therebetween, as will be clear from Figure 2. In that manner, the elements of the thermocouple 12 are connected to the terminal leads of the electromagnet coil 66 Y for energizing the latter, when the hot junction 14 of the thermocouple 12 is heated by the flame of the pilot burner 13.

a A suitably formed lever 83 is pivoted at its midlength for swinging movement in inlet chamber 23, on a pin 84 extending therethrough and mounted at its ends in the side walls of valve body 20. The lower portion of lever 84 straddles the valve stop and closure member 36 and is connected thereto, at opposite sides thereof, by pin and slot connections 85. The lever 83 is of approximately H shape, comprising two side arms, one of which is shown at 86, connected by a cross member 81 through which pin 84 passes. A block 88 is disposed between the upper ends of arms 86, to which it is connected by pin and slot means comprising a pin 89 passing through blo k 88 and extending, at each end, through a slot 90 in arm 86. A reset stem 9| is secured at its inner end to block 88 and extends therefrom outward through the outer or front wall of valve body 20, in concentric spaced relation to a surrounding nipple 92 projecting outward from that wall. Nipple 90 receives and guides a button 93 secured on the outer end of stem 9| and recessed from its inner end, for reception of the outer end portion of a coil compression spring 94 disposed about stem 9| and confined between button 93 and a washer 95, adjacent the inner end of nipple 9|, through which stem 9| slides. Packing material 96, confined between the washer 95 and the inwardly tapering inner end of nipple 92, is compressed by spring 94 about stem 9| so as to provide a fluid tight seal thereabout.

The current generated by the thermocouple, when it is heated, energizes coil 66. The magnetic field of the electromagnet is not of sufficient strength to move the armature 53 outward from its full line position shown in Figure 2, but is of suflicient strength to hold the armature 53 in its outward position when it has been moved into contact with the pole ends of the magnet frame 51. By pressing the reset button 93 inward, the valve stop and closure member 36 is moved outward and armature 53 is likewise moved outward into contact with the pole ends of magnet frame 51, in which position it is held by the electromagnet, if at that-time the thermocouple I2 has been and is being properly heated.

A valve stem 91 is secured at its inner end in boss 34 of valve 3|, and is slidably mounted, at its outer portion, in a boss 98 of back wall 99 of the valve body 20. Valve stem 91 is provided, at its mid portion, with a double cone element I of a size to pass through an opening MI in the back wall of a cupped spring cage I02 in the inner end of which is suitably secured a retainer ring I03 defining an opening of proper size to accommodate element I00. An annular coil tension spring I04 is mounted within spring cage I02 about valve stem 91 and is confined between ring I03 and the back wall of cage I02, so as to be restrained against movement axially of the cage. Spring I04 has an interior diameter but slightly greater than the diameter of valve stem 91, when this spring is in its fully retracted position, as shown.

A valve operating lever I05 extends upwardly within chamber 24 of valve body 20, this lever being provided at its lower end with a fork defining two arms, one of which is shown at I06, Which straddles valve cage I02 and are connected thereto, at opposite sides thereof, by pin and slot con-- nections I0'I. Lever I05 is provided, adjacent its upper end, with two conical recesses I08 and I09 extending from its outer and inner faces, respectively, recess I09 receiving a conical point IIO of a setting screw III threaded through a boss II2 extending inward from the front wall of the upper portion of chamber 24. This portion of the front wall of chamber 24 is thickened at H3 and is suitably recessed for reception of astufiing box H4 providing a fluid tight seal aboutthe stem of the screw III, the latter being provided at its outer or forward end with an enlarged knurled head I I5 to facilitate adjustment thereof. Recess I00 receives a conical point II6 of a plunger III slidable through a boss IIB extending inward from back wall 99 of valve body adjacent the upper end of this wall. Boss H8 is coaxial with nipple 2|, which is provided with a stepped recess H9 extending from its outer end. The in-' nor reduced portion of recess II9 receives the outer end portion of a metal tube I20 secured in provides an upper fulcrum about which the lever I05 may swing in either direction in the adjustment of screw II, point 0 of screw III providing a second and lower fulcrum about which lever I05 may swing in either direction responsive to expansion and contraction of tube I20. A coil compression spring I seats, at its outer end, in

' the position of plunger I I I, and by adjusting screw nipple H by a pressed fit therein. A closure plug I2I is suitably secured in the inner end portion of tube I20, conveniently by a circumferential rib pressed inwardly from the tube into a corresponding groove formed in plug I2I, there being a sealing cap I23, of suitable material, at theinner end of tube I20 and effecting a fluid tight seal thereof. A rod I24 is secured at its inner end in plug I2I, conveniently by being screwed therein, this rod extending coaxially within tube I20 and seatin at its outer end, in a recess in plunger I I1. Tube I20 has a greater coeflicient of expansion than rod I24 and, when it contracts, forces rod I24 in an outward direction, that is, a direction toward the valve body 20, expansion of tube I20 causing movement of rod I24 inward; that is, in a direction away from the valve body 20.

It will be seen that point II6 of plunger II! III lever I05 may be adjusted by this screw, in cooperation with spring I25, in either direction about point N5 of plunger III, for a purpose which will appear presently.

A supplementary housing I30, flanged at its imier end, is secured on the outer end wall of housing 44 in a suitable manner, conveniently by means of screws I3I, with an intervening sealing gasket I 32, housing I30 overlying an opening I33 through the outer or front end wall of housing 44. A corrugated metal bellows I3 1 is mounted within housing I30 by means of a nipple I35 flanged at its inner end, extending through the end wall of housing I30 and secured thereto by a nut I36 screwing on nipple I35 and clamping the adjacent portion of wall I02 between the flanged inner end of nipple I35 and nut I30. The body of the bellows I34 is formed of metal corrugated to bellows shape, as stated, and is secured at its outer end to the flange at the inner end of nipple I35, by soldering or in any other suitable manner, to provide a fluid-tight and pressure-resistant seal therebetween. The other end of the body of the bellows I30 is soldered or otherwise suitably secured to a flange I38 at the inner end of a cylindrical head I30 extending into the body of the bellows and substantially filling the space therein surrounded by the corrugated bellows body. A trip finger I 40, of generally L shape, is suitably secured at its outer end, conveniently by means of a screw Idfla, to the inner end of head I30 and extends therefrom through opening I33 and along the outer side of the other leg of the magnet frame 57, that is, the leg thereof about which the coil 00 is not mounted. Coil to is provided, at each end thereof, with a disc I4I of insulating material, these discs extending about and outward beyond the leg of magnet frame 5? along which the trip finger I00 extends. The discs MI are slotted for reception of trip finger I40 and, together with the adjacent leg of magnet frame 52, guide this finger .able metal, is secured at one end within nipple I35, there being a wiping I43 of solder or other suitable material about the outer end of nipple I35 and the adjacent portion of tube I42 to provide a fluid-tight seal therebetween. Nipple I35 is provided with a restricted orifice I44 through its inner end opening into the interior of the bellows I34 for flow of fluid into and from the latter. Tube I42 is extended into the hot water tank 5, through a suitable stuffing box I45, providing a fluid-tight and pressure-resistant closure about the tube, and is secured at its other end to one end of a bulb I46 in free communication therewith, this bulb being sealed at its other end and disposed within the tank so as to be exposed to the temperature of the water or fluid within this tank. The bulb I45 and tube I42 contain a thermosensitive fluid, as does the bellows I34, which may be either liquid or gaseous, this fluid expanding responsive to increase in temperature and contracting responsive to decrease in temperature. The bellows I34 normally is held, by its inherent resiliency, in its collapsed condition shown in Figure 2, at which time the inner end of trip finger I40 is spaced outward a short distance from the inner end of the adjacent leg of the magnet frame 51. It will be noted from Figure 3 that the armature 53 is of somewhat greater extent than the magnet frame 51 and projects outward beyond the legs of this frame, the edge portion of armature 53 adjacent trip finger I40 being in the path of movement thereof when this finger is moved inward.

It is intended that the pilot burner 13 be lit at all times so long as the cock remains in open position, so that the hot junction 14 of the thermocouple 12 is heated and the coil 66 of the electromagnet is energized. In Figure 2, the control valve closing and guide member 36 is shown in its inner or operable position, with the armature 53 released from the magnet frame 51 and spaced inwardly therefrom. Member is then held in its inner or operable position by compression spring 52, supplemented by spring 94, closing the valve 3| and assuring that this valve is maintained in its closed position so long as member 36 remains in its inner or operable position. Closing of valve 3| interrupts flow of fuel to the main burner I, with resulting extinguishment thereof. In order to reignite the main burner and set the control means into operation, the reset button 93 is pressed inwardly to a sufficient extent to move member 35 outward into its outer or inoperable position, with armature 53 seating against the pole ends of the magnet frame 51, as shown in Figure 3. Since the electromagnet normally is energized, the armature 53 is held thereby in its outer position, together with the valve closing and stop member 36, in opposition to the springs 52 and 94, both of which, at that time, are compressed, the strength of the magnetic field generated by the coil 61, when the thermocouple is heatedby the pilot burner, being sufficient for that purpose. With the member 36 held in its outer or inoperable position, the hub 35 of valve 3| is slidable in member 30, and the valve 3| may be opened and closed independently of member 35. It may be assumed, for purposes of description, that member 35 is in its attracted outer position, as in Figure 3, and the valve 3| is in its closed position, into which it has been moved responsive to a. desired maximum temperature of the body of fluid within the tank 5. Accordingly, under the conditions assumed, the water within tank 5 has been heated to the desired maximum temperature, and the supply of fuel to the main burner 1 has been cutoff, thus extinguishing'that burner. As the temperature of the water within tank 5 decreases, the tube I20 contracts and rod I24 is moved lengthwise toward the valve body 20, thus urging the lever I05 in a clockwise direction about the point IIU'of adjusting screw III. That results in moving the spring cage I02 and the parts carried thereby outward along the valve stem 91 toward wall 99, the spring I04 moving along the double cone element I00 and being expanded radially thereby during such movement. As the spring I04 passes over the central portion of element I00, that is, the portion thereof of maximum diameter, it contracts about the outwardly tapering outer portion of element I00 and forces stem 91 inward with a snap action, until the valve 3| is in its outermost position in contact with the valve stop and closing member 30, at which time valve 3| is in its full open position, shown in Figure 3. That reestablishes flow of fuel to the main burner 1, which is reignited by the pilot burner 13 for again heating the water in tank 5. The burner I then functions to heat the water in tank 5, and as the temperature of the water increases the tube I20 expands, moving rod I24 outward and permitting movement of lever I05 in a counterclockwise direction about the point IIO of adjusting screw III. During this movement of lever I05 valve stem 31 is restrained against inward movement, by contact of valve 3| with member 36, as in Figure 3, and remains stationary until spring I04 passes over the center of element I00, at which time this spring contracts about the inner inwardly tapering portion of element I00 and moves the valv 3| into its closed position, with a snap action. Valve 3| is held closed until the temperature of the water within tank 5 decreases to a desired predetermined minimum, at which time the spring I04 passes outwardly beyond the center portion of element I00, again opening valve 3| in the manner previously described. By adjusting the screw III the desired minimum and maximum temperatures at which opening and closing of the valve 3| will occur, responsive to the temperature of the water within tank 5, may be varied so that the control may be set for any desired minimum and maximum temperatures, within limits. The control means thus provides comparatively simple and safe means for automatically turning on and off the main burner 1 responsive to desired minimum and maximum temperatures of the water within tank 5.

The thermoresponsive trip means, comprising the valve I46 and bellows I34 and associated parts, provides safety means assuring extinguishment of the main burner'1 in the event of failure of the lever I05 and associated parts, for any reason, to close valve 3| when the temperature of the water withintank 5 reaches the desired predetermined maximum. In such case the water within the tank could be heated to a temperature in excess of the desired maximum, and objectionably high pressures with resulting damage or injury might occur. In the event of the water within tank 5 being heated to an objec-' tionably high temperature, in excess of the predetermined desired high temperature, the ex- ,pansion of the fluid within bulb I40 and tube I42 and bellows I34 causes expansion of the latter, moving the trip finger I40 inward along the adjacent leg of the magnet frame 51, into contact with the armature 53. As the trip finger I40 continues to move inward, it forces the armature 53 away from the pole ends of the magnet frame, thus releasing it therefrom, and member I33 is moved inwardly, by the expansive force of spring 52 supplemented by the expansive force supplements the action of the springs 52 and 94 for closing the valve, and thereafter the springs I04 and 52 and 94 cooperate to assure that the valve 3| is maintained in its closed position. In order that the valve 3| may again be placed under control of lever I05, after the condition which prevented closing of the valve has been remedied, the valve closing and stop member 36 is reset to its inoperable position by pressing the reset button 93 inwardly, as above described. Extinguishment of the pilot burner 13 results in cooling of the hot junction 14 of th thermocouple '12, with resulting deenergizing of coil 66 of the electromagnet so as to release the armature 53, the member 36 being then moved inward into its operable position effective for closing valve 3| and maintaining it closed in the manner above described. Valve 3i cannot thereafter be reopened until member 36 is reset into'its inoperable positionin the manner above explained. In order to effect the resetting operation, it is necessary that the pilot burner be lit in order to heat the hot junction of the thermocouple, and that the resetting button 93 be maintained in its in-.

ner position, holding armature 53' in contact with the pole ends of the magnet frame 51, until the hot junction of the thermocouple has been heated sufliciently to generate electric current for energizing the coil of the magnet and thereby holding armature 53 in its outer position. That means that the resetting operation cannot be completed until the condition causing extinguishment of the pilot burner has been remedied and the pilot burner has been relighted. Accordingly, no fuel can be supplied to the main burner 1 unless the pilot burner is lit, which eliminates danger of fuel being supplied to the main burner and escaping therefrom without being ignited.

The control means of my invention comprises, briefly, a main burner and means normally operable for controlling supply of fuel to the main burner responsive to different temperatures generated by such burner, means for shutting off flow of fuel to the main burner responsive to an objectionably high temperature generated thereby, and means under control of the pilot burner adjacent the main burner for igniting the latter and receiving fuel in advance of the means for controlling the supply of fuel to the main burner, the pilot burner controlled means being effective for assuring closing off of the fuel supply for the main burner responsive to failure of the pilot burner. While I prefer to employ the thermostat means shown and above described for opening and closing the fuel control valve responsive to desired predetermined minimum and maximum temperatures generated by the main burner, and also prefer to use the thermostat means shown and described for assuring closing of the fuel supply control valve responsive to an objectionably high temperature generated by the main burner, any other suitable means may be used, in either case, within the broader aspects of my invention.

It will be understood that changes in construc-' said conduit, means subject to heat generated by said main burner for opening and closing said valve responsive to a desired minimum anda desired maximum temperature, a pilot burner for igniting said main burner connected to said conduit in advance of said valve, a valve closing member movable to an inoperable position permitting opening and closing of said valve and yieldingly urged toward an operable position assuring closing of said valve and maintaining it closed, means, comprising an electromagnet connected in circuit with a thermocouple subject to the heat of said pilot burner and an armature for said electromagnet, effective for holding said member in its inoperable position when the pilot burner is lit and for releasing it upon extinguishment of said pilot burner, and means subject to heat generated by said main burner for releasing said armature from said electromagnet and thereby said member from its inoperable position responsive to a temperature in excess of the desired maximum.

2. In control means of the character described, a main burner, a fuel supply conduit therefor, a valve controlling flow of fuel through said conduit, a first thermoresponsive means subject to heat generated by said burner for opening and closing said valve with a snap action responsive .to a desired minimum and a desired maximum temperature, a pilot burner for igniting said main burner connected to said conduit in advanceof said valve, a thermoelectric generator heated by the flame of the pilot burner, a valve closing member movable to an inoperable position permitting opening and closing of said valve and yieldingly urged toward an operable position assuring closing of said valve and maintaining it closed, said member in its inoperable position providing a stop limiting opening of said valve, an armature connected to said valve closing member for holding it in its inoperable position, an electromagnet energized by said thermoelectric generator effective when energized for holding said armature in its attracted position, said electromagnet when energized being ineffective for moving said armature from its released position to its attracted position, resetting means for moving said valve closing member from its operable position to its inoperable position and thereby moving said armature from its released position to its attracted position, said resetting means including means yieldingly urging said valve closing member toward its operable position, and a second thermoresponsive means subject to heat generated by said main burner for releasing said armature from said electromagnet responsive to a temperature in excess of the desired maximum.

3. In control means of the character described, a valve body comprising an inlet chamber and an outlet chamber with a valve port therebetween, a

valve controlling said port, a stem secured at one end to said valve extending therefrom into said outlet chamber and slidable therein at its other end portion, a valve operating lever mounted in said outlet chamber for swinging movement and yieldingly urged in one direction, thermostat means operatively connected to said lever for swinging it in the other direction and permitting tion permitting opening and closing of said valve and yieldingly urged toward an operable position effective for closing said valve and maintaining it closed, an armature connected to said member for holding the latter in its inoperable position, an electromagnet effective when energized for holding said armature in its attracted position and thereby holding said valve closing member in its inoperable position, said electromagnet being ineffective for moving said armature from its released position to its attracted position, reset means for moving said valve closing member from its operable position to its inoperable position and thereby moving said armature to its attracted position, and a second thermostat means effective for releasing said armature from said electromagnet responsive to a predetermined high temperature.

4. In control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controlling said port, a stem secured to said valve extending therefrom into said outlet chamber, a valve operating lever mounted in said outlet chamber, means comprising a thermostat for swinging said lever in opposite directions responsive to decrease and increase in temperature, said valve stem being provided with an element tapering from itscentral portion toward each end of said stem, means disposed about said stem for relative movement lengthwise thereof comprising a radially expandible and contractible member disposed for engagement with the inclined areas of said element and effective by contraction thereabout for urging said stem and valve axially in closing and opening directions, a valve closing member in said inlet chamber having an operstem, means comprising a thermostat for swin ing said lever in opposite directions responsive to predetermined minimum and maximum temperatures, a valve closing member having an inoperable position permitting opening and closing of said valve and yieldingly urged toward an operable position eflective for closing said valve and maintaining it closed, electromagnetic means able position eiiective for assuring'closing of said valve and maintaining it closed and an inoperable position permitting opening and closing of said valve by said resilient member, connections between the latter member and said lever for imparting movement to said resilient member lengthwise of said valve stem in accordance with movement of said lever, an armature connected to said valve stop member for holding the latter in its inoperable position, an electromagnet effective when energized for holding said armature in attracted position and thereby holding said valve closingmember in inoperable position, said electromagnet being ineffective for moving said armature from released position to attracted position, a second thermostat means efiective for releasing said armature from said electromagnet responsive to a predetermined objectionably high temperature, and reset means for moving said valve closing member from its operable position to its inoperable position and thereby moving said armature into attracted position, said reset means comprising means yieldingly urging said valve closing member toward its operable position.

5. In control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controlling said port, a stem secured to said valve extending therefrom into said outlet chamber, said stem being provided intermediate its ends with a double conical element taperin from its center portion toward the ends of said stem, a spring cage disposed about said stem, a radially expandible and contractible resilient member mounted in said cage cooperating with the tapered surfaces of said element for moving said stem and valve in opening and closing directions, an operating lever connected to said cage for moving the latter lengthwise of said tionably high temperature.

6. In-control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controlling said port, a valve stem secured to said valve extending therefrom into said outlet chamber, said stem being slidably mounted at its outer end portion in said valve body, a lever mounted in said outlet chamber, said lever and said valve stem being provided with cooperating means for opening and closing said valve responsive to movement of said lever from one position to another position, means comprising a thermostat for moving said lever from said one position to saidother position and vice versa responsive to a desired predetermined minimum and maximum temperature, said valve having a coaxial projection at the inlet chamber side thereof, a valve closing member coaxial with said valve slidably receiving said projection, means yieldingly urging said valve closing member into operable position effective for assuring closing of said valve and maintaining it closed, a stem attached at its inner end to said valve closing member for moving the latter outward into an inoperable position permitting opening and closing of said valve, said valve closing member when in its inoperable position receiving and guiding said projection of said valve and providing a stop limiting opening of said valve, an armature attached to the outer end of said second stem, an electromagnet effective when energized for holding said armature in attracted position and thereby holding said valve closing member in its inoperable position, and means comprising a second thermostat for releasing said armature from said electromagnet responsive to an objectionably high temperature.

7. In control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controlling said port, thermoresponsive means for opening and closing said valve responsive to a predetermined low temperature and a predetermined high temperature, a valve closing member having an inoperable position permitting opening and closing of said valve and an operable position eifective for assuring closing of said valve and maintaining it closed, said member when in its inoperable position slidably receiving and guiding a portion of said valve and limiting movement thereof in opening direction, an armature attached to said valve closing member for holding it in its inoperable position, an electromagnet effective when energized for holding'said armature in attracted position but ineffective for moving said armature from its released position to its attracted position, reset means for moving said valve closing member to its inoperable position and thereby moving said armature to its attracted position, said reset means comprising means yieldingly urging said valve closing member toward its operable position, and thermostat means for releasing said armature from said electromagnet responsive to a temperature in excess of said desired maximum temperature.

8. In control means of the character described,

a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controllin said port, thermoresponsive means for closing and opening said valve responsive to a desired maximumtemperature and a desired minimum temperature, a valve closing member having an inoperable position permitting opening and closing of said valve and an operable position assuring closing of said valve and maintaining it closed, said member having sliding connection with said valve for guiding the latter in its opening and closin movement when said valve closing member is in its inoperable position, an abutment member, a stem attached at its inner end to said valve closing member and slidable through said abutment member, an armature attached to the outer end of said stem, an electromagnet effective when energized for holding said armature in its attracted position but ineffective for moving said armature from its released position to its attracted position,. said armature and said stem holding said valve closing member in its inoperable position when said armature is in its attracted position, a compression spring confined between said abutment member and said valve closing member urging the latter toward its operable position, a lever in said inlet chamber pivoted between its ends connected at one end to said valve closing member for movin the latter to its inoperable position and thereby moving said armature to its attracted position, a reset stem slidable through a wall of said inlet chamber and connected to the other end of said lever for moving said valve closing member to its inoperable position upon inward movement of said stem, means comprising a compression spring about said reset stem urging the latter outward of said valve body, both of said springs being compressed and coacting to urge said valve closing member into its operable position when said armature is in its attracted position, and thermoresponsive means for releasing said armature from said electromagnet responsive to a temperature in excess of said desired maximum.

9. In control means of the character described, a valve housing having an inlet chamber and an outlet chamber with a valve port therebetween,

a valve controlling said port, thermoresponsive means for opening and closing said valve responsive to a. desired predetermined minimum temperature and a desired predetermined maximum temperature, a valve closing member having an inoperable position permitting opening and closing of said valve and an operable position assuring closing of said valve and maintalning itclosed, an armature attached to said member for holding it in its inoperable position when said armature is in attracted position, an electromagnet effective when energized for holding said amature in attracted position but ineilective for moving said armature from its released position to its attracted position, said electromagnet comprising a magnet frame, resetting means for moving said valve closing member from its operable-position to its inoperable position and thereby moving said armature from its released position to its attracted position, a normally collapsed bellows fixed at one end to said valve body, a trip finger attached to the other end of said tive when energized for holding said armature bellows slidable thereby along said magnet frame and disposed to contact said armature and force the latter away from the magnet frame and thereby release it, when said trip finger is moved in one direction by expansion of said bellows, said reset means comprising-yielding means urging said valve closing member toward its operable position, and thermoresponsive means connected to said bellows for causing expansion thereof responsive to a temperature in excess of said desired maximum.

10. In control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a. valve controlling said port, thermoresponsive means for opening and closing said valve responsive to a predetermined desired minimum temperature and a predetermined desired maximum temperature, a valve closing member in said inlet chamber having an inoperable position permitting opening and closing of said valve and an operable position assuring closing of said valve and maintaining it closed, an armature attached to said member for holding the latter in its inoperable position, an electromagnet efiecin its attracted position, said electromagnet being ineffective for moving said armature from its released position to its attracted position, reset means for moving said valve closing member from its operable position to its inoperable position and thereby moving said armature from its released position to its attracted position, said reset means comprising means yieldingly urging said valve closing member toward its operable position, and thermoresponsive means comprising a bellows and a trip member actuated thereby for forcing said armature away from said electromagnet and thereby releasing it therefrom responsive to a temperature in excess of the desired maximum.

11. In control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controlling said port, thermoresponsive means for opening and closing said valve, a valve closing member having an inoperable position permitting opening and closing of said valve and an operable position assuring closing of said valve and maintaining it closed, a reset lever pivoted between its ends connected at one end to said valve closing member for moving the latter into its inoperable position, an abutment member, a stem attached at one end to said valve closing member and slidable through said abutment member, an armature attached to the other end of said stem, an electromagnet efiective when energized for holding said armature in its attracted position but ineffective for moving said armature from its released position to its attracted position, a pilot burner, a thermocouple connected in circuit with said electromagnet and subject to the heat of said pilot burner, a reset stem slidable through a wall of said inlet chamber connected to the other end of said lever, a compression spring confined between said abutment member andsaid valve closing member, a compression spring about said reset stem urgreset stem moving said valve closing member into its inoperable position and thereby moving said position, and condition responsive trip means for releasing said armature from said electromagnet for movement of said armature to released position and movement of said valve closing member to operable position 12. In control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controlling said port, condition responsive means for mechanically opening and closing said valve responsive to a first condition and a second condition, a, valve closing member having an inoperable position permitting opening and closing of said valve and an operable position effective for mechanically closing said valve and maintaining it closed, electromagnetic means effective when energized for holding said valve closing member in inoperable position but ineffective for moving said valve closing member from its operable to its inoperable position, condition responsive means for releasing said valve closing member.

from said electromagnetic means and moving it to operable position, and reset means for moving said valve closing member from its operable to its inoperable position.

13. In control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controlling said port, means for mechanically closingand opening said valve responsive to a predetermined high temperature and a predetermined low temperature, a valve closing member having an inoperable position spaced from said valve permitting opening and closing of the latter and yieldingly urged toward an operable position effective for mechanically closing said valve and maintaining it closed, electromagnetic means effective when energized for holding said valve closing member in inoperable position but inefiective for moving said member from its operable to its inoperable position, means responsive to a predetermined high temperature for releasing said valve closing member from said electromagnetic means, and reset means for moving said valve closing member from its operable to its inoperable position.

14. In control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controlling said port, thermostatic means for mechanically opening and closing said valve to maintain selected temperatures, a valve closing member having an inoperable position permitting opening and closing of said valve and an operable position effective for mechanically closing of said valve and maintaining it closed, said valve having an extension and said member when in its inoperable position slidably receivin and guiding said extension and thereby guiding said valve in its opening and closing, electromagnetic means eifective when energized for holding said valve closing member in its inoperable position, and thermoresponsive means for releasing said valve closing membe from said electromagnetic mean responsive to a predetermined temperature.

15. In control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controlling said port, thermostatic means for mechanically opening and closing said valve to maintain selected temperatures, a valve closing member having an inoperable position permitting opening and closing of said valve and an operable position efiective for mechanically closing of said valve and maintaining it closed, electromagnetic means effective when energized for holding said valve closing member in its inoperable position, and 'means efiective for mechanically urging said valve closing member away from said electromagnetic means with a force suflicient to release it therefrom.

16.- In control means of the character described, a valve body having an inlet chamber and an outlet chamber with a valve port therebetween, a valve controlling saidport, thermostatic means for mechanically opening and closing said valve to maintain selected temperatures, a valve closing member having an inoperable position permitting opening and closing of said valve and an operable position effective for mechanically closing'of said valve and maintaining it closed, electromagnetic means eflective when energized for holding said valv closing member in its inoperable position, and thermoresponsive means effective for mechanically urging said valve closing member away from said electromagnetic means with a force sufficient to release it therefrom responsive to a predetermined temperature.

HAROLD A. MAN'I'Z.

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