US2379712A - Thermoelectric safety device and the like - Google Patents

Description

July 3, 1945. c, v, HILDBRECHT 2,379,712

THERMOELECTRIC SAFETY DEVICE AND THE LIKE Filed sept. 14, 1942 l "Patented Qty 9 i ,rimini Charles V. mldebrecht, Chicago, Ill., assigner to Milwaukee Gas Specialty 4 Company, `Milwaukee/Wis., a corporation of Wisconsin Application September 14, 1.942, Serial No. 458,304

` 4 claims. (cl. 137-139) This invention relates to an improvement in thermoelectric safety devices vand the like.

Thermoelectric safety devices which depend y upon the small E. M. F. that can be produced by the heat of a iame upon a thermocouple or other thermoelectric generator for maintaining the desired iiowof fuel, for example, for a main burner, and which operates to shut oii the4 flow of fuel upon extinction, for example, of a pilot' flame, usually require reset means for resetting the deupon the other valve seat to shut E the? supply of fuel tothe burner during the resetting operation and until the pilot lameV has been relighted and a ther-moelectric current set up to hold the armature in attracted position, whereupon the shutoff valve member is adapted to move to open position tween the two valve seats upon release ofthe vice.l These reset devices usually mdve an armature to attracted position and, simultaneously, the shutoi valve member to the position in which it is held ,by the armature when the armature is held ,attracted to the electromagnet by the energization thereof. Y Ii thel valve member or other control device is operated to set up the supply oi fuel whenever the reset device is operated and irrespective of whether the pilot burner is lighted, fuel may pass, for; example. 'to the main burner and escape and o lect unburned. This unburned gas presents the danger of asphyxiation and possible explosion when a ilame is applied to light the pilot burner.

One ci the main objects of the present invention is to provide means which will permit resetting the armature to attracted position without setting up the desired supply of fuel to the burner, and, particularly, means which will permit resetting and holding the armature infattracted position without setting up the desired supply of fuel Referring to the drawing, the burner i0 is any to the burner until the pilotame has been re, .I

lighted and a thermcelectric current set up to hold the armature in attracted position.

In its more speciiic aspects, the present invention utilizes the shutoff valve member as the means for shutting of! the supply of fuel for the main burner during the resetting operation, thereby rendering unnecessary a second valve memiber or other device for accomplishing this resul Still more speciiically. the shutoff valve member lof the present invention is in the form of a double ,r faced valve member operating between two valve seats. As long as the thermoelectrlc generator is heated bythe pilot light or other llame, the resulting energization of the electromagnet holds the amature in attracted position and' the shutoif valve member in open position between the two valve seats for Ithe supply of fuel to the main burner. Upon extinction o f the pilot light the shutoii' valve member moves to-positionseating upon one of the valve seats to shutoii' the supply I of fuel to the burner. ln resetting the device the shutoff valve member is moved to position seating reset means, and is held in that position by the attraction of the armature to the electromagnet.

Further objects and advantages of the invention will be apparent from the following detailed description, taken in connection with the accompanying drawing in which:

Figure l is a fragmentary and more or less diagrammatic view showing an embodiment of the present invention in a pilot burner and mainv burner gas supply system;

Figure 2 is a vertical section through the thermoelectric safety valveshown in Figure 1; and

Figure 3 is a fragmentary detail section of a modification showing means for permitting continued movement of the armature -toward the magnet frame after theI valve is closed in the resetting operation.

suitable or preferred main burner, and the conduit Il is -the fuel supply conduit therefor.

Associated with the main burner I 0 is the usual or any suitable or preferred pilot burner, indicated more or less diagrammatically at I2, which opilot burner is intended to remain lighted for the purpse of relighting the main burner upon extinction thereof, This pilot burner I2 is supplied with gaseous fuel by a tube I3 connected, for example, at I4 to the conduit I I.

The thermo'electric'safety valve, designated in its entirety at I5. comprises a valve casing I8 connected into the conduit I I. :'[n theillustrated embodiment of the invention, the valve casing I6" is shown connected into .the conduit II posterior to thefpilot burner connection I4, but this may vary within the broader invention. Y

The interior of the\ valve casing I6 is divided by a partition wall I'I into Aan inlet chamber I8 and an outlet chamber I9.' A pair of annu'fr` valve seat members 20 and 2|, suitably secured in the wall Il, deilneA Vapair of valve openings I' 22 and 23 through which the Vinlet chamber I8 is adapted 'to be placed in communication with the outlet .chamber I9. 'I'he valve member 241s resiliently pressed against the upper end of the walveseat member 2| by compression spring 25 to shut on the flow of fuel to the burner I0 when aspects of the present 26; 1s deenergized.

The electromagnet 26 is disposed within the hood 21 which may be secured, as by means of screws (not shown) to the top of the valve cas; ing i6. 'I'he electromagnet 26. comprises a generally U-shaped magnet frame 28 provided about each of its legs with a coil 29; The magnet frame 28 is held rigidly toma magnet mounting plate 30 by means of a bracket 3| whichis secured to the plate 38 by screws 32. The plate 3|] is, in turn, secured to the hood. 21 by a screw 33.

'Ihe magnet armature 35 is adapted to have engagement with the pole faces at the ends of the legs of the U-shaped magnet 28. This armature 35 isguided for reciprocatory movement within upright guide lugs 36 on an armature guide 31 which is secured tothe hoo'd 21 by screws 39. The armature 35 has attached thereto byupwardly extending bent-over portions 40 a cradle 4| which, in turn, is connected to the upper end of the valve stem 42 by means of a generally U-shaped retainer 43 engagingin a groove in the upper end of the stem 42 and' cooperating with the inturned lower end of the cradle 4|. A limited universal connection is thus provided between. the armature 35 and the upper end of the stem 42.

The under surface of the valve disc member 24 has a gasket or yielding facing 45,c1amped in a' recess in the valve disc and between the disc and a washer 46 by a nut 41 lthreaded upon the stud 48 integral with and depending from which extend into diametrically opposite elongated slots in the hollow stem 63, thus provviding a lost motion connection between the valveI member 24 and the valve stem 42 and, at the same time, a limited universal connection for permitting the valve member 24 to accommodate itself to its valve seats.

'Ihe valve stem 42 has axial reciprocatory movement through the armature guide 31, and the opening through the guide 31 is preferably sealed, .for example, by packing, as indicated at 56. A packing washer may be provided at 51, and the coiled spring 25 is interposed between Vthe packing washer and the nut 52. The armature, electromagnet and circuit connections are thus sealed from the fuel which passes through the valve casing-.|6.

The reset'means comprises a reset stem 6l)A lextending downwardly, as the device is viewed in the drawing, through a reset housing 6| threaded into an openingin the valve casing |6. The inner end ofthe reset stem 68 has ahead 62 which" limits outward movement of the reset stem, and when the reset stem is pressed inwardly, cooperates with the stud 48 toreset. the

device. The stem has fixed on its outer iid a" reset button 6 3 secured to the stem, for example,

by threading it upon the outer end of the stem;- Packing-may be provided at 64 for sealing the inner end of the reset housing 6 against the escape of gas from the valve casing I6. A coiled spring 65, confined endwise between the button elements.

the hot junction 12 in position to be'heated the electromagnet, indicated in its entirety at 63 and a packing wasner 66, normally maintains the resetA stem in its outwardly projected position and returns the same to that position following release of the button 63 upon completion of the resetting operation. The spring 65 also holds the packin'ttightly about the stem 60 and the opening at the inner end of the reset housing 6|. In order to prevent unwarranted actuation of the button 63 a closure cap 6B is threaded upon the lower end of the reset housing 6|, and when in vplace completely encloses the button 63. This cap 68 is removedv to reset the device. Gaskets are preferably provided at 69 and 69a.

The .thernroel'ectric generator is illustrated in the form of a thermocouple comprising an outer tubular thermocouple element 10 which, at one end, is welded or joined to the inner element 1| l to provide a hot junction 12 between the two 'I 'he thermocouple is disposed with by the pilot ilame as shown 4more or less diagrammatically in Figure 1 so as to be responsive to the heat of the pilot ame. The outer tubular thermocouple element 10 is joined at its opposite end, asby means of welding or the like, to a tubular couple connector 14. The opposite end of the tubular connector, which may be formed ofcopper or other suitable metal, is-

joined as by welding or -the like to the adjacent end .of a tubular lead conductor 16. AExtending through the tubular lead conductor 1 6 is a lead conductor or wire 11 which may be an insulated wire and which, within the connector 14, is

joined at 18 to the innerl thermocouple element 1|. 10 and 1|, respectivelyVare formed of dissimilar metals, such as constantan and chrotnel,"V

electric valve and is secured as by means of a welded joint at 18 within a reduced portion 19 .of a connector which is threaded into and electrically contacts the hood. Within the connector 80 is provided an insulating sle ve 8| disposed about the adjacent end of thef nductor 11 and enclosing the connector 82 between the conductor 11 andthe terminal conductor 83 of one of the coils 2s. The other,oi1'termins1 is 29 aboutthe legs of vthe magnet frame 28 and the conductors 16 and 11 leading tothe thermojunction 1.2.]

jig-"Aftergth 'connections are made between the 'g-electroniagnet and the lead tube 16 and conductor 11, and between the eiectroniagnet and the connector 80, the space between 'the electromagnetand .the upper 'portion of the hood 21 is preferably lled with the sealing compound 84 for 6? holding the parts in position and sealing the same in place. 'I'his compound also seals the hood against the leakage of any gas which may leak out into the hood past the packing at 56 or around the armature guide 31; f I

In Figure' 2 I have shown a coiled spring 82 interposed between the valve'dis'c member 24 and the adjacent end of the stem 42 for permitting continued movement of the valve disc member The outer and inner thermocouple elements ment with the'magnet frame 28. This assures v ber 20.

In Figure 3 Lhave shown, more or less diagrammatically, spring means in the form of a spring washer 95 between the yielding valve facing 50 and the valve disc member 24' for permitting continued movement of the armature into engagement with the magnet frame after the valve disc member 24', and particularly the spring-pressed facing 50 thereof, is seated upon the valve seat member 20. The valve facing 50' is shown as having sliding action in the annular recess 96 in the valve disc member 2,4'. In Figure 3, the armature is moved to attracted position by engagement of the valve disc member 24 at the lower ends of the slots 55' directly with the cross pin 54', whereas in Figure 2 the armature is moved to attracted position through the coiled spring 92. The parts shown in Figure 3, which correspond with parts shown in Figure 2, have primed reference characters corresponding with the reference characters used in Figure 2.

The operation of the device is as follows:

When the pilot flame is burning, the heat of the pilot flame upon the junction 12 of the thermocouple produces a thermoelectric current in the coils 29 of the electromagnet 26. The magnet frame 28 and armature 35 are preferably formed of permaloy, hypernic, or a similar alloy of relatively low magnetic reluctance, and, as a result, the relatively weak .thermoelectric current produces a magnetic eld in the magnet frame and armature of suicient strength so that when the magnet armature is placed in contact with the ends of the magnet frame by pushing the reset `button 63 inwardly, the magnetic attraction between the magnet frame and the armature holds the armature in attracted position against the magnet frame with a force greater than the force exerted by the spring 25, thereby holding the valve 24 in open position between the valve seats 20 and 2| as shown in Figure 2 of the drawing. It will be noted that with the armature 35 in attracted position the valve member 2t is adapted t`o be moved inwardly into engagement with the valve seat 2t. When the armature is held in attracted position and the reset button is released, as will presently appear, the spring 25 moves the valve member 25 away from the valve seat 2o to its open position between the valve seats, and the cross pin 54 limits the movement of the valve member 2t toward the valve seat 2i with the armature in attracted position.

If the pilot flame goes out, the thermoelectric current through the electromagnet ceases, and the spring 25 moves the valve member 2t to closed position against the valve seat 2i. The spring 25 also assures detachment of the armature from the electromagnet upon deenergization of same and notwithstanding anyresidual magnetization therein. 'I'he closing of the valve 24 against the valve seat 2| shuts oif the supply of gas to the main burner l il.

The E. M. F. produced by the heat of the pilot light on the junction l2. of the thermocouple is not suilicient to energize the electromagnet suiiiciently to draw the armature upwardly from its retracted position, and therefore the valve is reset by removing the cap 68 and pushing the button 63 inwardly to raise the amature into contact with the magnet frame 28. As thel reset stem is pushed inwardly in the resetting operation, the head 62 thereof abuts the stud 48 which,

vby the inward movement of the stem, shifts the valve member 24 from seating engagement'with the valve seat 2| into seating engagement with thevalve seat 20. The seating of the valve member 24 upon the valve seat 20 shuts off the flow of fuel to the main burner during the resetting operation. It will lbe noted that in resetting the device the armature 35 is first moved into good contact with the pole faces at the ends of the magnet frame 28, and the lost motion connection provided by the cross pin 54 and the slots 55 permits continued movement of the valve member 24 into seating engagement with the valve seat 2|) after the armature is in attracted position. This assures proper positioning of the armature in attracted position and against any improper positioning of the armature by reason of the valve member 24 engaging its valve seat 20 iirst and preventing continued resetting operationI of the armature.

If the pilot burner is lighted and sets up a thermoelectric current to hold the armature 35 in contact with the pole faces of the electromagnet, the valve stem 42 will be held in the position shown in Figure 2 of the drawing. Then when the reset button E3 is released, the spring 25 will move the valve member 2t away from the valve seat 2li to open position between this valve seat 2li and the valve seat 2l as shown in Figure 2 of the drawing. As previously pointed out, the cross pin 54 limits the movement of the valve member 24 toward the valve seat 2| with the armature 35 in attracted position so that the valve member 2E will be maintained in proper open position between the respective valve seats. If, on the other` hand. the pilot burner is not lighted to produce the thermoelectrio current for holding the valve 24 in open position, this valve will move to closed position against the valve seat 2| upon release of the button 63, and in this manner a single shutoff volve member operates to prevent the passage of fuel to the main burner until the pilot burner is lighted and a thermoelectric current set up to hold the armature in contact with the pole faces of the electromagnet. After resetting the device and releasing the resetting button 63, the cap t@ may be replaced.

The embodiment of the invention shown in the drawing is for illustrative purposes only, and it is to be expressly understood that said drawing and the accompanying specification are not to be construed as a denition of the limits or scope of the invention, reference being had to the appended claims for that purpose.

l claim:

l. In a safety control valve of the character described, a valve casing having an inlet chamber and an outlet chamber with a valve chamber therebetween provided with an inlet port and an outlet port respectively opening into said inlet and outlet chambers for establishing communication therebetween, a valve stem, said inlet and outlet ports and said valve stembeing coaxial, a valve member mounted on said stem for limited relative movement lengthwise thereof disposed within said valve chamber between` and controlling said ports. an armature attached to said valve stem, means yieldingly urging said stem and valve member toward a released position with said valve member seating over the outlet port, an electromagnet effective when energized for holding said armature and said valve stem in attracted position with said valve member disposed between and spaced from said ports but incapable of moving said amature and stem from released to attracted position, and reset means for moving said amature and stem y from released to attracted position and moving said valve member from released position to a resetting position seating over said inlet port.

2 In a safety control valve of the character described, a valve casing having an inlet chamber and an outlet chamber with a valve chamber therebetween provided with an inlet port and an outlet port respectively opening into said inlet and outlet chambers for establishing communication said stem toward a released position with saidv valve member seating over said outlet port, an electromagnet effective when energized for holding said armature and said valve stem in attracted position with said valve member disposed between and spaced from said ports but incapable of moving said armature and stem from released to attracted position, and reset means for moving said armature and stem from released to attracted position and moving said valve member from released position to a resetting position seating over said inlet port.

3. In a safety control valve of the character described, a valve casing having an inlet chamber and an outlet chamber with a valve chamber therebetween provided with an inlet port and an outlet port respectively opening into said inlet and outlet chambers for establishing communication therebetween, a. valve stem, said inlet and outlet ports and said valve stem being coaxial, a valve member mounted on said stem for limited relative movement lengthwise thereof disposed within said valve chamber between and controlling said ports, an armature attached to said valve stem, means yieldingly urging said stem and valve member toward a released position with said valve member seating over the outlet port, an electromagnet eil'ective when energized for holding said v armature and said valve stem in attracted position with said valve member disposed between and spaced from said ports but incapable of moving said armature and stem from released to attracted position, reset means for moving said armature and stem from released to attracted position and moving said valve member from released position to a, resetting position seating over said inlet port, and means supplementary to said yielding means yieldingly urging said valve member outward of said stem permitting relative movementbetween said valve member and said stem toward said elec tromagnet in the resetting operation.

4. In a safety control valve of the character described, a valve casing .having an inlet chamber .and an outlet chamber with a valve chamber therebetween provided with an inlet port and an outlet port respectively opening into said inlet and outlet chambers for establishing communication therebetween, a valve stem, said inlet and outlet ports and said valve stem being coaxiala valve member mounted on said stem for limited relative movement lengthwise thereof disposed within said valve chamber between and controlling said ports, an armature attached to said valve stem, means yieldingly urging said stem and valve member toward a released position with said valve member seating'over the outlet port, an electromagnet effective when energized for holding said armature and said valve stem in attracted position with said valve member disposed between\and spaced from said ports but incapable of moving said armature and stem from released to, attracted position, reset means for moving said armature and stem from released'to attracted position and moving said valve member from released position to a resetting position seating over said inlet port,

and a compression spring confined between said stem and said valve member urging the latter outward of said stem and permitting relative movement between'said valve member and said stem toward said electromagnet in the resetting operation.

' CHARLES V. HILDEBRECHT.

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