US2455542A

US2455542A - Safety device for fuel burners

Info

Publication number: US2455542A
Authority: US
Inventors: Weber Victor; Russell F Garner
Original assignee: Robertshaw Fulton Controls Co
Current assignee: Robertshaw Controls Co
Priority date: 1944-04-01
Filing date: 1944-04-01
Publication date: 1948-12-07
Anticipated expiration: 1965-12-07

Description

1943- v. WEBER ETAL 42 SAFETY DEVICE FOR FUEL BURNERS FilQd April 1, @944 3 Shaeis-Sheet 1 INVENTORS. Vzc TOR 602052 Eusssu. F. Gmwvak Meir ATTORNEY Dec. 7, 1948. v. WEBER ETAL SAFETY DEVICE FOR FUEL BURNERS 3 SheetsSheet 2 Filed April 1, 1944 z mm.

INVENTORS. Vzcroe (ell-0E2 5 1903551. 1. f1 Gan/v52 the/P ATTORNEY Dec. 7, 1948.

5 Sheets-Sheet I Filed April 1, 1944 1 w I! VOW INVENTORS. Vzc 7'02 cTEasef ,Pusszu. E Gan/v52 BY WM\ 15/18 ATTORNEY Patented Dec. 7, 1948 SAFETY DEVICE FOR FUEL BURNEBS Victor Weber. Greensburg, and Russell F. Garner,

Youngwood, Pa., asalgnors to Robertshaw- Fulton Controls Company, a corporation of Delaware Application April 1, 1944, Serial No. 529,201

8 Claims. 1

This invention relates to safety controls for fuel burners and, more particularly, to' thermoelectric devices for controlling flow of gaseous fuel to water heaters and like appliances.

Appliances of the type indicated have been provided with electrically operated safety valves which are energized by current generated by a thermoelectric device exposed to the flame of the pilot burner. The safety valve is thus operable for shutting off the flow of fuel to the main and pilot burners of the appliance when the pilot burner becomes extinguished. Various means have also been provided to render the thermoelectric device incapable of maintaining the safety valve open during the normal operation of the burners if a dangerous condition arises, such as excessive temperature or pressure in the water being heated by the burners.

An object of this invention is to improve such devices by providing positive acting means to shut-off the flow of fuel to the main and pilot burners whenever a predetermined water temperature is reached.

Another object of the invention is to accomplish the shut-off by operation of the thermoelectric safety valve but independent of the current generated by the thermocouple.

Another object of the invention is to insure positive actuation of the safety valve to closed position both in the event of pilot flame extinguishment or excessive water temperature.

Another object of the invention is to prevent flow of fuel to the main burner until the pilot burner produces a flame.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawings,

wherein Fig. 1 is a schematic view of a water heater having the safety control of this invention applied thereto;

Fig. 2 is a plan view of the safety control;

Fig. 3 is a. section taken on the line III-III of Pi 2;

Fig. 3a is a partial section taken Illa-Illa of Fig.

Fig. 4 is a section taken on the line IV-IV of Fig.

Fig. 5 is a partial section taken on the line V-V of Fig. 2;

Figs. 6 to '10 inclusive are plan and elevational views of details of a lever mechanism incorporated in the control;

Fig. 11 is a longitudinal section through a modified form of control;

on .the line Figs. 12 and 14 are partial sections taken on line XII-Jill of Fig. 3 showing the different port positions of the main control valve; and

Figs. 13 and 15 are partial sections taken on line XIII-XIII of Fig. 3 showing the different by-pass passage positions of the main control valve.

Referring more particularly to Fig. 1 of the drawings, the main burner ill of a water heater i2 is supplied with gaseous fuel through a pipe l4 and the pilot burner is for the main burner is supplied with gaseous fuel through a pipe i8. The fuel supplied to both the main and pilot burners is controlled by the control device 2i of this invention and which will be more fully described hereinafter. The pilot burner it produces a flame which serves to heat a thermocouple element positioned adjacent thereto and upon extinguishment of the pilot burner flame the thermocouple 26 will cool and cause the gas supply to the main burner it to be cut off by operation of the control device 2i of this invention. I

Referring now more particularly to Figs. 2, 3 and 4 of the drawings, the control device M of this invention comprises a housing formed of two main parts, namely/a valve body as and a magnet body 26. These parts are suitably bolted or otherwise secured together and sealed against leakage of gaseous fuel through the joints thus formed.

The valve body 24 is adaptedfor insertion in the pipe l4 by provision of an inlet 28 at one end thereof and an outlet 30 at the opposite end thereof to which the pipe i4 may be threadedly connected. Between the inlet 28 and the outlet 30 is a valve seat 32 with which a valve member 34 is adapted to cooperate to control flow of fuel from the inlet 28 to the outlet 30. The valve -member 34 is reciprocable toward and away from the seat 32 by a stem 36 supported in the valve body 24 and is biased away from the seat 32 by a coil spring 38 extending between the body 24 and the valve member 34.

The valve stem 36 projects through the valve member 34 into a valve chamber 40 formed in the valve body 24 in communication with the inlet 28 and providing an opening 42 in the valve body which is closed by the magnet body 28.

The valve body 24 is also provided with a tapered valve seat '44 extending transversely of the inlet 28 and in which a tapered plug valve member 46 is mounted for rotation. The plug valve 46 is provided with a port 48 extending transversely therethrough and which may be moved into alignment with the.inlet 28 for passage of fuel to the valve chamber 48. A dial 58 carrying the indicia On," Pilot and Off is secured to a stem 5I projecting from the larger end of the plug valve 48 exterior of the valve body 24 and provides manual means for rotating the plug valve 48 in the valve body to selected positions.

The larger end of the plug valve 48 is provided with an arcuate groove 52 formed in its surface and serving in selected positions of the valve to connect the opposite ends of a by-pass passage 54 formed in the valve body and which the tapered valve seat 44 intersects. One end of the by-pass passage 54 communicates with the inlet 28 and the opposite end communicates with a passage 56 leading to a pilot valve stem chamber 58 (Fig. 4) extending axially in a boss 59 on the magnet body 26 and communicating at one end with the main valve chamber 48. Reciprocably mounted in the valve chamber '58 in a valve stem 68 provided with longitudinal recesses for passage of fuel from the valve stem chamber-58 into an enlarged pilot valve chamber 82 which overlies the chamber 58 and connects therewith. The valve stem 88 has an end projecting into the main valve chamber 48 and serving to support a sealing device 83 to prevent fuel flow between the main valve chamber 48 and the chamber 58. Passage of fuel between the valve stem chamber 58 and the valve chamber 82 is controlled by a pilot valve member 84 secured to the valve stem 88 and movable into and out of engagement with a valve seat 88 formed on the shoulder intermediate the

chambers

68 and 62.

The pilot valve member 84 is biased into engagement with its seat 58 by a coil spring 88 extending between the valve member 84 and a cap I8 which forms a closure for the chamber 62. Communicating with the chamber 82 is a passage 12 formed in the magnet body 28 and leading to a connection I4 for the fuel supply pipe 88 of the pilot burner I6. A suitably apertured adjusting member I8 for the pilot burner fuel supply may be mounted for manual rotation in a boss I? formed on the magnet body 28 and having an axial opening intersecting the passage I2. Adjustment of the member I8 which projects exteriorly of the magnet body serves to vary the orifice size of the passage I2.

As hereinbefore indicated, the valve mechanism of the present invention is provided with an arrangement for causing both the control valve 34 and the pilot burner valve 84 to move to closed position upon extinguishment of the pilot burner,

I6. This mechanism is mounted in the magnet .housing 26 which is provided with an enlarged will be understood that any other arrangement which will provide sufilcient flow of current through the coils 82 to energize the magnet 88 may be provided. An armature member 84 is provided for the magnet 88 and is carried on a stem 86 which projects on either side t ereo a d supports on one side a coil spring 88 extending between the armature 84 and the bottom of the magnet 88. The coil spring 88 is stronger than the spring 38 for the valve member 34 and acts in opposition thereto for seating the valve member 34 as will be apparent hereinafter.

The end of the stem 88 projecting on the opposite side of the armature 84 threadedly engages with a cap nut 98 which is located in valve chamber 48 in proximate relation to the projecting end of the valve stem 36 with which it is axially aligned. The cap nut 98 may beguided in an apertured retained plate 92 which serves as a closure for the open end of the enlarged recess I8 and also serves to secure a sealing gasket 94 across the open end to prevent passage of fuel from the valve chamber 48 into the magnet body 28.

As the voltage generated by the thermocouple 28 is relatively small, the spring 88' will serve to maintain the armature 84 in its released position, as shown in Fig. 3, even if the magnet is in energized condition. As is customary in such devices, means areprovided for resetting the armature 84 against the pole faces of the magnet 88 by a manual operation owing to the lack of sufficient magnetizing force to attract it from released position. To this end, a reset stem 96 is mounted for reciprocation in a reset stem chamber 91 formed in the magnet body 26 on one side of the magnet 88. The reset stem 96 carries a nut '98 projecting on the exterior of the magnet body 28 and is urged outwardly from the chamber 91 by a coil spring I88. The outward movement of the stem is limited by a collar I82 on the reset stem 96 which engages with a flanged portion I83 of the magnet body 28 forming a guide for the stem 98. Beyond the collar I82 the reset stern projects through an aperture into the valve chamber 48 for the purpose of effecting actuation ofmeans for resetting the'armature 84 as described and also to maintain the control valve 34 seated during the resetting operation.

The means for accomplishing this dual function includes a channel-shaped plate I84, shown in detail in Fig. 6, which has its base secured to the magnet body 26 with the opposite sides thereof projecting into the valve chamber 48. A pair of spaced slots I86, I88 are formed in each of the sides of the channel-shaped member I84 and a perforation H8 is provided in the base thereof through which the projecting end of the reset stem 98 may extend. An operating lever II2, shown in detail in Figs. 8 and 8a, is pivoted intermediate its ends in the slot I88 and is provided with a raised portion H4 at one end which engages with the cap nut 98 on the end of the armature stem 86. The operating lever H2 is further provided with an elongated opening H6 within which a connecting lever I I8, illustrated in Fig. 9 of the drawings, is adapted to extend.

The connecting lever II 8 has a forked end I 28 which extends on both sides of the operating lever H2 at one end I2I thereof, this end being suitably bent from the plane of the lever to facilitate such engagement. A slot I22 is formed transversely in the end of the connecting lever II8 opposite the forked end I 28 and is adapted to receive an upturned portion I24 formed intermediate the ends of a holding lever I26 illustrated in Fig. 10 of the drawings. One end of the holding lever I28 is pivoted in the slots I88 of the channel-shaped member I84 and this end is also provided with an opening I28 for the reception of the forked end I28 and the associated end I2I 5. of the connecting and operating levers. respectively. I

When the lever mechanism described is positioned in the valve chamber 48 the end of the holding lever I28 opposite its pivot extends along the underside of the operating lever I I2 and into operative engagement with the projecting end of the control valve stem'88. Extending laterally of the raised portion II4 on the operating lever H2 is an arm I88 having an upturned end I82 which is adapted to engage with the projecting end of the pilot valve stem 88 as illustrated in Fig. 4 of the drawings.

In addition to the features of the safety control so far described, the embodiment of the present invention includes an arrangement for causing closure of the control valve 84 and the pilot burner valve 84 when the temperature .of the water in the water heater I2 becomes excessive. This arrangement includes means by which it is possible to move the armature 84 to its released position and cause closure of the safety control valve 84 independently of the current being generated by the thermocouple 20. To this end, the magnet body 28 is provided with a cover I84 within which an expansible and contractible element I 88 of a thermally responsive device is mounted. Expansion and contraction of the element I88 may be made responsive to the temperature in the water heater I2 by the provision of a capillary tube I88 connected at one end to the element I88 and at the other end to a bulb I40 immersed in the water being heated. The bulb I48, capillary tube I88 and element I88 may be completely ililed with a fluid which remains liquid at elevated temperatures such as chiorin ated diphenyl.

As shown more clearly in Fig. 3a, the element I88 is carried on a stud I88 supported from an arm I48 mounted on the upper end of the magnet body 28. The element I38 is thus free to expand and contract as described and such movements will serve to reciprocate a pin I42 projecting from the element I88 at the side opposite the stud I88. The pin I42 projects through an aperture in the upper end of the magnet body 88 and through an axially alignedaperture in the bottom of the horseshoe magnet 88. The pin I42 is thus arranged in axial alignment with the stem 88 of the armature 84 and is adapted for engagement therewith when the armature 84 is seated against the pole faces of the magnet 88. In this condition of the armature 84 the spring 88 is compressed. When the armature 84 is in its released position the spring 88 is extended and the stem 88 is spaced from the end of the pin I42.

In the operation of the device the dial is first rotated from the i'f" position to the Pilot" position. The position of the plug valve port 48 and by-pass groove 82 in the "Off" position is illustrated in Figs. 12 and 13. Until the Pilot position is reached no fuel can pass the plug valve 48 and both the pilot and main burner control valves are in closed position. In the "Pilot" position the fuel may flow from the inlet 28 by way of the arcuate groove 82 to the pilot passage 84 to the pilot valve stem chamber 88. The reset button 88 is then manually actuated to depress the stem 88 and cause its engagement with the connecting lever II8. Furtherpressure applied to the reset button "88 will cause the stem 88 to move the forked end I2Il'of the connecting lever III downwardly carrying with it the associated end I2I of the operating lever II2.

As the operating lever H2 is pivoted intermediate its endsin the slot I 88 of the channelshaped member I84. the opposite end of this operating lever will move upwardly causing the raised portion II4 engaging the cap nut 88 to move the armature 84 toward the pole faces of the magnet 88. At the same time. the extended arm I88 of the operating lever II2 will also move upwardly causing engagement between the up= turned end I 82 thereon with the projecting end of the pilot valve stem .88. Thus, when the arma ture 84 isin the attracted position in engagement withthe pole faces of the magnet 88,- the pilot control valve 84 is moved oil its seat against the bias of the spring 88. Fuel may then how past the pilot control valve 84 and from the chamber 82 which it controls to the passage I2 and to the pilot connection I4 and pipe I8 to the pilot burner I8 at an amount controlled by the adjustment of the pilot adjustment member 18. The pilot burner may then be lighted and the flame therefrom will impinge upon the end of the thermocouple 28 which is connected with the coils 82 of the magnet 88.

During this resetting operation, the connecting lever H8 pivots around the upturned portion I2 1 of the holding lever I28 as a fulcrum. The holding lever I28 is thus held stationary against the projecting portion of the control valve stem 88 while the raised portion I I 4 of the operating lever II2 moves away therefrom in engagement with the cap nut 88. The control valve 84 is thus held firmly against its seat 32 against the bias of its spring 88 to prevent fuel flow to the main burner should the plug valve 88 be positioned with its port 48 aligned with the inlet 28.

In a short time the thermocouple 28 generates sufilcient current to energize the magnet and maintain the armature 86 in its attracted position against the pole faces of the magnet. The reset button 88 may then be released causing retraction of the stem 88 under the bias of spring I88. The consequent release of pressure on the holding lever I28, permits the control valve spring 35 to move the control valve 38 to open position carrying with it the holding lever I28 which is pivoted in the slots, I88 of the charmed-shaped support I84. The dial 88 may then be rotated to the On position shown in Figs. 14 and 15 permitting fuel to flow from the pipe I4 through the inlet 28 to the valve chamber 40 and past the valve seat 32 to the oulet 88 connected with pipe id to the main burner I8. In this position of the plug valve 48 it will be observed that the arcuate groove 62 permits fuel to flow to the pilot burner through the same passages as in the "Pilot" position. As the spring 88 of the main control valve 84 is stronger than the spring 68 of the pilot control valve the operating and holding levers are maintained in raised position and the pilot valve 84 is held open during normal running of the burner.

In the event that the pilot burner is extinguished. the thermocouple ceases to generate current causing deenergizatlon of the electro- Movement of the armature 84 away It the burner continues to operate without extinguishment of the pilot burner I6 and consequent operation of the safety control described, an excessive temperature may occur in the water being heated in the water heater I2. Upon occurrence of this condition, the thermal element I36 will undergo an expanding action and move the pin I42 connected thereto toward the armaturestem 86. As the pin I42 is in engagement with the stem 86 in the attracted position of the armature, the magnetic force tending to hold the armature against the pole faces of the magnet is overcome and the spring 88 will move the armature 84 to its released position. This action of the thermal element I36 in overcoming the magnetic force between the magnet 80 and its armature 84 is thus entirely independent of the current generated by the thermocouple 20. It will be apparent that this positive release of the lever I26. The rocker then pivots on its pin support compressing the spring I 64 until the armature 84 is seated against the pole faces of the magnet 80. The pilot burner may then be lighted and the thermocouple will generate suilicient current to retain the armature in attracted position while the dial 50 is released. Movement of the reset stem under bias of spring I52 will relieve the holding pressure of rocker end I60 on holding lever I26 and permit valve spring 38 to open the control valve 34 as in the previous embodiment. The following operations to bring the control into running condition are as previously described in connection with the preferred embodiment.

It will be understood that many" changes may be made in the arrangement and combination of parts and in the details of construction herein disclosed within the scope of the appended claims without departing from the spirit of the invenarmature 84 and consequent closure of the contion.

trol valve 3| and the pilot valve 64 may occur under conditions of excessive temperature in the water heater even though the pilot flame has not been extinguished and thermoelectric current is still being generated.

In the embodiment shown in Fig. 11 a modified form of resettin device is disclosed. As the other elements of the construction are identical in all respects with those previously described, similar reference numerals have been applied to the corresponding parts. In this embodiment, the plug valve 46 is provided with stem I44 movable axially thereof and carrying the dial 50. The stem 4 and dial are biased from the valve body 26 by a coil spring I46 extending between the underside of the dial 50 and a cover I48 which limits axial movement of the valve stem Ill.

The reset stem I50 of this embodiment is located intermediate the plug valve 46 and the magnet 80 and is mounted in a chamber I5! formed in the magnet body26. As in the previously described embodiment, a coil spring I52 serves to urge the reset stem I50 outwardly from the magnet body but the reset button of the previous embodiment is dispensed with. In place thereof an actuating arm I54 is mounted on the reset stem I50 exterior of the magnet body 26 and projects I into position to be engaged by the dial 50 upon axial movement thereof. The opposite end of the reset stem I50 projects into the valve chamber 40 and is formed'with a cup-shaped end I56 which is preferably rectangular in cross-section. A pin extends transversely through the rectangular end I56 and through downturned ears formed on a rocker I58 which takes the place of the connecting lever of the previous embodiment. The rocker I58 pivots on the pin and is provided with a depending end I60 and an opposite depending end I62. A coil spring I64 extends between depending end I62 and the end I56 of the reset stem. A projection I66 on end I62 of the rocker is adapted to engage one end of the operating lever'II2'Tvhich-rnaybe similar to that described in the previous embodiment. The opposite end I60 of the rocker is adapted to engage with the holding lever I26 which also may be similar to that described in the previous embodiment.

The operation of the embodiment shown in Fig. 11 differs from that previously described only in the resetting operation. In the Pilot position the dial 50 is pushed inwardly toward the valve body by a manual operation and serves to move the reset stem I50 do rdlyas vieweddiil lg.

, vllw 'l heprd ection I66 of rocker I58 pivots the operating lever H2 in support I04 while the depending end I60 restrains movement of holding We claim:

1. An electromagnetic device comprising an electromagnet member and an armature member movable relatively thereto between attracted and released positions, means for establishing magnetic force between said members suflicient to maintain said attracted position, and an expansible element operatively engageable with one of said members and being movable therewith relative to the other said member upon expansion of said element to exert a force on said one of said members sufficient to overcome said magnetic force and cause movement to said released position.

2. An electromagnetic device comprising an electromagnet having an armature movable relatively thereto between attracted and released positions, means for energizing said electromagnet to establish magnetic force between said electromagnet and armature sufflcient to prevent said relative movement, and temperature responsive means having an actuating portion operatively engageable with said armature and being movable therewith relative to said electromagnet upon sufficient variation in temperature to cause said movement to said released position by overcoming said magnetic force.

3. An electromagnetic device comprising an electromagnet having an armature movable rela tively thereto between attracted and released positions, means for biasing said armature to said released position, means for overcoming said biasing means and causing said movement to attracted position, means for energizing said electromagnet to establish magnetic force between said electromagnet and armature sufficient to prevent said relative movement from attracted position, and temperature responsive means having an actuating portion operatively engageable with said armature and being movable therewith relative to said electromagnet upon, suificient variation in temperature, said temperature responsive means being cooperable with said biasing means to cause said relative movement to released position by overcoming said magnetic force.

4. An electromagnetic device comprising an electromagnet having an armature movable relatively thereto between attracted and released positions, means for biasing said armature to said releasei pqsltio n, means for overcoming said biasing means amausing said movement to attracted position, a source of eleEtric current, means for conducting current from said source to said electromagnet to establish a magnetic force sumcient to prevent said relative movement from attracted position, a temperature responsive device movable in accordance with temperature variations, and means for transmitting movement of said temperature responsive device to said armature for overcoming said magnetic force and causing said relative movement to released position by said biasing means.

5. An electromagnetic device comprising an electromagnet having an armature, means for supporting said armature for movement relative to said electromagnet between attracted and released positions, means for biasing said armature to said released position, manually operable means carried by said support for moving said armature to attracted position against said biasing means, a source of electric current, means for conducting current from said source to said electromagnet to establish a magnetic force sufllcient to prevent movement of said armature from attracted position, an expansible element mounted on said support, and movement transmitting means connecting said element to said armature in the attracted position thereof, said element being adapted upon expansion thereof to exert a force on said armature suflicient to overcome said magnetic force and cause movement of said armature to released position by said biasing means.

6. Safety control apparatus for heating appliances having a burner and means supplying fuel thereto, comprising electromagnetic means having an armature movable relatively thereto between attracted and released positions, means for energizing said electromagnetic means to establish a magnetic force sumcient to prevent said relative movement, a control device operatively associated with said electromagnetic means for controlling flow of fuel to the burner in accordance with said positions, and means responsive to temperature changes caused by operation of the burner and operatively engageable with said armature for movement therewith relative to said electromagnetic means for effecting said movement to released position by mechanically overcoming said magnetic force.

7. Safety control apparatusfor heating appliances having a burner and means supplying fuel thereto, comprising electromagnetic means having an armature movable relatively thereto between attracted and released positions, means for biasing said armature to said released position, means for overcoming said biasing means and causing said movement to attracted position, a

current from said source to said electromagnetic means to establish a magnetic force sufilcient to prevent said relative movement from attracted position, a control device operatively associated with said electromagnetic means for controlling flow of fuel to the burner in accordance with said positions, a temperature responsive device movable in accordance with temperature changes caused by operation of the burner, and motion transmitting means extending between said temperature responsive device and said armature for transmitting movement of said temperature responsive device to said armature for mechanically overcoming said magnetic force for effecting said relative movement to released position by said basing means.

8. Safety control apparatus for heating appliances having main and pilot burners and means for supplying fuel thereto, comprisin electromagnetic means having an armature movable relatively thereto between attracted and released positions, thermoelectric means responsive to a said magnetic force.

VICTOR WEBER. RUSSELL I". GARNER.

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

UNITED STATES PATENTS Number Name Date 2,217,785 Beta et a1. Oct. 15, 1940 2,285,294 Lange Dec. 9, 1941 2,273,127 McGoldbrick et al. Feb. 17. 1942 2,276,909 Alfery Mar. 17, 1942 2,283,903 Ashcroft May 28, 1942 2,288,890 Denison July I, 1942 2,299,654 Ray Oct. 20, 1942 2,303,701 Manta Dec. 1, 1942 2,809,709 Paille Feb. 2, 1948 2,340,234 Thornbery et a1. Jan. 29, 1944 2,850,978 Alfery J1me 13, 1944 2,301,277 Manta June 19, 1944