US2183827A - Thermoelectric safety switch and the like - Google Patents

Description

. 19, 1939. J. H. THQRNBERY 2,183,827

THERMOELECTRIC SAFETY SWITCH AND THE LIKE Filed Aug. 22, 1935 jg 62 f1}: 60 D ZTLUGW'LZZUTI 51 2 7g fokn korrzer y.

M KM-(W0 Patented Dec. 19,.19w

UNITED sm'rss mm QFFIQE John H. Thornbery, Milwaukee, Wis assignor to Milwaukee Gas Specialty Company, Milwaukee, Wis, a corporation of Wisconsin Application August 22, 1935, Serial No. 87,276

16 Claims.

My invention relates to an improvement in thermoelectric safety switches and the like While the particular device with which I shall describe the present improvement, hereinafter in connection with the drawing, is the thermoelectric safety switch shown and described in the copending application of John HxThornbery and Harold A. Mantz, Serial No. 14,551, flied April 4, 1935, it is to be understood that the present invention is not limited to use with this particular device but may be employed with all similar devices and elsewhere as suitable or desired. For example, the present improvement may be used with the thermoelectric safety valve and switch combination shown and described in the copending application of Thomas T. Arden, Serial No. 76,988, filed April 29, 1936, as well as with other thermoelectric safety switches and thermoelectric safety valves and devices of similar character.

Thermoelectric safety devices, which depend upon a weak voltage thermoelectric current for maintaining the flow of fuel to the main burner and which operate to shut ofi the flow of fuel to the burner upon extinction of the pilot flame, require resetting means for resetting the device after the pilot flame has been extinguished. These resetting devices usually move the armature into contact with the pole faces of the elecw tromagnet and, simultaneously, the switch or other control device to position for setting up the supply of fuel to the'main burner. If the switch or other control device is operated to set up the supply of fuel to the main burner when the 185 resetting device is operated and, irrespective of whether the pilot burner is lighted, fuel may pass to the main burner and escape and collect unburned. This unburned gas presents the danger of asphyxiation and possible explosion when a 40 flame is applied to light the pilot burner.

The object of the present invention is to provide means which will permit resetting and holding the armature in contactwith the pole faces of the electromagnet without setting up the supply of fuel to the burner, and, particularly, means which will permit resetting and holding the armature in contact with the pole faces of the electromagnet without setting up the supply of fuel to the burner until the pilot flame has been relighted and a thermoelectric current set up to hold the armature in contact with the pole faces of the electromagnet.

In its more specific aspects, the resetting device has a resetting button provided with a closure cap, and the supply of fuel is not set up to the burner until the pilot flame has been relighted to set up a thermoelectric current to hold the armature in contact with the pole faces of the electromagnet and the closure cap has been applied into position covering the resetting button. 55

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 as diagrammatic view showing an embodiment of the present invention in a pilot burner and main burner. gas supply system;

Figure 2 is a vertical section through the thermoelectric safety switch shown in Figure 1; w and Figure 3 is a fragmentary detail section.

Referring to the drawing, the pipe It, which may be the gas supply pipe for the main burner II, is provided with an electrically operated valve 20 H of a type well known in the art.

The heater is diagrammatically indicated at it,

" and the main burner H, which may be associated therewith in any suitable or preferred manner, may be controlled by the valve It. This valve 12 has electrically controlled mechanism connected into an electric circuit 15 which may be provided with a thermostat Hi to be opened or closed in accordance with the temperature of the room heated by the heater, where the heater is a room heater, or the thermostat it may be aruanged to be opened and closed in accordance with the temperature of the water in the tank, where the heater is a water heater, or otherwise as desired. The circuit 16 may include the secondary winding of a transformer H, which may be connected to a suitable source of current.

Associated with the main burner ii, in the usual or-in any suitable or preferred manner, is a pilot burner indicated more or less diagrammatically at It, which pilot burner is intended to remain lighted and which may be of any suitable construction. This pilot burner 18 is supplied with gaseous fuel by a tube as connected at 28 45 to the pipe it ahead of the valve It.

The thermoelectric switch, indicated in its entirety at 22, is the same as that shown and described in the copending application of John H. Thornbery and Harold A. Mantz, Serial No. 14,551, 50 flled April 4, 1935, except for the presentimprovement as will hereinafter appear. This switch comprises an upper hood or housing mem- 'ber 23 secured by cap screws 24% to the lower switch housing 25.

The hood 23 is provided with a central inwardly extending boss 28 which forms a flat supporting surface for receiving a magnet mounting plate 29 which is secured to the boss 28 by a screw 38. The electromagnet, indicated in its entirety at 3|, is disposed within the hood 23 and to the top of the hood 23 by a screw 31.

The ends of the legs of the U-shaped magnet 32 constitute pole faces, and the magnet armature 48 is adapted to have engagement with these pole faces of the electromagnet. 40 is guided for reciprocatory movement within upright guide lugs 42 on an armature guide 43 which is secured to the hood 23 by screws 44. The armature 48 has attached thereto, by upwardly extending bent-over portions 45, a cradle 46 which, in turn, is connected to the upper end of a reciprocatory stem member 41 by means of a U-shaped washer or clip 48 engaging in a groove in the upper end of the stem 41 and cooperating with the inturned lower end of the cradle 46. A

limited universal connection is thus provided between the armature 40 and the upper end of the reciprocatory stem member 41.

The stem member 41 has axial reciprocatory movement within the armature guide 43. The stem member passes through a packing washer 50, and the recess 5| in the member 43 is preferably provided with packing 52 above the washer 50. The provision of the packing 52 is optional, this packing being provided for use when the lower housing member is employed as a valve housing for a valve member carried at the lower end of the stem 41 for closing oif the flow of fuel through a fuel line, as, for example, in the thermoelectric safety valve described in the copending application of Oscar J. Leins, Serial No. 4,741, filed February 4, 1935, or in the combination valve and switch structure shown and described in the copending application of Thomas T. Arden,

Serial No. 76,988, filed April 29, 1936.

The reduced lower end of the stem 41 is threaded to thread into the upper stem portion of a resetting button 54, and a collar 55 is preferably interposed between the lower end of the enlarged portion of the stem 41 and the upper end of the stem of the button 54. Positioned loosely upon the stem portion of the button 54 is a contact disc 56 which is adapted to bridge andconnect a pair of spring contacts 51 and 58. The contact 51 is connected to a terminal screw 59 which secures the contact to the lower housing member 25. The contact 58 is secured in place upon the bottom of the housing member 25 by a screw 68 and has an upturned end 6! adjacent a threaded opening 62 through the bottom of the housing 25 and coaxial with respect to the resetting button. A third spring contact 63 is connected to a terminal screw 64, which secures this contact to the housing member 25. The contact 53 has an upturned end 65 disposed in spaced relation to the upturned end of the contact 58 and adjacent the opening 62.

The terminal screws 59 and 64 have the usual nut members 66 for connecting the terminals to conductors 61 and 68. These conductors connect the terminals 59 and- 64 through the circuit 95 to suitable terminals 10 for the electrically. controlled actuating mechanism within the hous- The armature ing carried by the electrically operated valve l2.

, The lower housing member 25 is preferably formed of insulating material, such as a molded phenol condensation product, whereby the terminal screws and contacts are insulated from eachother. It is to be understood that the terminal screws and contacts may be insulated from each other otherwise as suitable or desired.

A coiled compression spring 12 surrounds the stem 41 and is interposed between the packing washer 58 and the collar 55. When the electromagnet is deenergized, as will hereinafter appear, 'this spring moves the stem 41 and, with it, the collar 55, resetting button 54, and armature 48, downwardly. The collar 55,- in its downward movement, strikes the contact disc 56 and moves the same downwardly out of contact with the contacts 51 and 58 to open the circuit between these contacts.

A second spring 13 surrounds the reduced stem portion of the button 54 and is interposed between the contact disc 56 and a shoulder 14 on the button 54. This spring, which is preferably a relatively weak spring, holds the contact dmc 56 yieldingly against the contacts 51 and 58 when the device is in the position shown in Figure 2, and at the same time permits the armature 48 to be pressed and held firmly against the ends of the legs of the magnet frame 32 without depending solely upon the yieldability of the contact springs 51 and 58.

The reset button 54 is provided with a closure cap 93 which has threaded engagement in the threaded opening 62 in the lower housing member 25. .A metal contact band carried by the upper end of the cap 93 closes the circuit across the contacts 58, 63 when the cap 93 is in place, and opens the circuit across these contacts when the cap is removed.

A suitable thermo-couple, comprising an outer tubular member 15, which, at one end, is welded to the inner element 16 as'shown at 11 for the purpose of providing a hot welded junction between the two members, is disposed with this junction in proximity to the pilot flame, as shown more or less diagrammatically in Figure 1, so as to be responsive to the heat of the pilot flame. The external element 15 is joined at its opposite end, as by welding or the like, at 18 to a tubular couple connector 19. The opposite end of the tubular connector, which may be formed of copper or other suitable material, is joined, as by welding or the like,at to the adjacent end of the lead tube 8|. 8| is the lead wire 82 which may be an insulated wire and which, within the connector 18, is joined at 83 to the internal element 16 of the thermocouple. The thermo- couple elements 15 and 16 are formed of dissimilar metals, such as "Constantan and Chromel, Chromel and Copel, or any other dissimilar metals which, when heated at the junction therebetween, are adapted t produce a thermoelectric current,

-The lead tube 8|, which may be formed of copper, extends to the thermoelectric switch 22,-

Extending through the tube completed through the coils 33 and the conductors 8| and 82 Leading to the hot thermo-couple Junction.

After the connections are made between the 5 electromagnet and the tube 8| and conductor 82, and between the electromagnet and the connector 85, the space between the electromagnet and the upper portion of the hood is filled with sealing compound, indicated at 98, for holding the parts 10 in position and sealing the same in place.

The operation of the device is as follows: When the pilot flame is burning the heat of this flame upon the junction ll of the thermo= couple produces a thermoelectric current in the coils 33 of the electromagnet. The magnet frame 32 and armature 40 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 field of sufiicient strength so that when the armature is placed in contact with the ends of the magnet frame by pushing the reset button 58 the magnetic attraction holds the armature in raised position against the frame with a force greater than the force exerted by the spring means, thereby holding the contact disc 56 in contact with the contacts 51 and 58 yieldingly through the spring 113.

If the pilot light goes out, the thermoelectric current through the electromagnet 3i ceases, and the spring means moves the stem 41 downwardly, the collar 55 striking the contact disc 55 and moving the same to open position.

The operation of the spring 12 in opening the switch is aided by gravity if the device is installed vertically, as shown, but this disc spring is preferably of sumcient tension to open the switch without the aid of gravity whereby the device may be installed in any desired position. The spring also assures detachment of'the armature from the electromagnet upondeenergization of the same and notwithstanding any residual magnetization therein. The opening of the circuit across the contacts 51 and 58 opens the circuit 95 for the safety control valve 12, whereupon this valve moves to closed position to close off the supply of gas to the main burner.

In resetting the device, the circuit I5 is closed by two independent operations.

tion after removal of the cap 83 is to engage the armature with the magnet poles where it will be held by magnetic force providing the pilot flame has heated the thermo-couple to its operating temperature. The operation of the reset button to engage the armature with the magnet poles brings the contactdisc 58 against the contacts 51 and 58 where it is held by the thermoelectric current when the pilot flame has heated the thermocouple to its operating temperature. The second 60 operation is to replace the 'reset cap 93. This replacement of the cap positions the contact band 94 in bridging engagement with the contacts 58, 83 to close the circuit therebetween. When the cap 93 is removed, the band 96 moves out of bridging engagement with the contacts 58, 63, opening the circuit between these contacts so that the circuit will not be closed to set up a flow of fuel to the burner it merely by the resetting operation and until the pilot burner has been lighted and sets up a thermoelectric current to hold the armature against the pole faces of the electromagnet and the reset cap 33 has been replaced.

I claim: 1. In combination, a'burner, a fuel supply congg duit, therefor, a valve in said conduit, an electric The first operacontrol circuit for said valve, a switch in said circuit, a thermoelectric device controlling said switch and comprising an electromagnet having coil means and a core, an armature, a thermocouple connected to said coil means for producing 5 a thermoelectric current therein to hold the armature against the core, means for resetting the armature against the core, and a second switch for opening said circuit during the resetting operation.- 10

2. A thermoelectric safety device comprising an electromagnet having coil means and a core, an armature, a stem carried by said armature, a housing for said device, a thermo-couple connected to said coil means for producing a-thermo- .15 electric current therein to hold said armature against said-core, a reset button for resetting said armature against the core, a cap having removable attachment to said housing for enclosing said reset button, contacts within said housing 20 and insulated from each other, and a contact member carried by said cap for bridging said first contacts when said cap is applied to the housing and opening the circuit between said first contacts when said cap is removed from the housing. 25

3 In combination, an upper hood, a lower housing member formed of insulating material, said lower housing member having a threaded opening, contacts within said lower housing member and having turned ends adjacent said opening, 30 a closure cap having threaded engagement in said opening, and a contact band carried by said cap for bridging the turned ends of said first contacts when said cap is applied to the lower housing member and opening the circuit between said 35 first contacts when the cap is removed.

4. A thermoelectric device comprising an upper hood, a lower housing member formed of insulating .material, an electro-magnet disposed in said hood and having coil means and a core, 40 an armature, a thermo-couple connected to said coil means for producing a thermoelectric current therein to hold said armature against said core, a stem having a universal connection with said armature, a pair of contacts within said 45 lower housing member, a bridging contact held yieldingly in engagement with said first contacts when said armature is engaged with said core, spring means for separating the armature from said core and the bridging contact from said first 50' contacts when said electromagnet is deenergized, means for resetting the armature in engagement with the core, a closurecap for said resetting means, a contact disposed within the lower housing member in proximity to one of said first 55 contacts, and a contact carried by said cap for bridging said last contacts when said cap is in place.

5. In combination, a safety valve, an electric circuit having a switch for controlling said valve, 60 a thermoelectric device comprising an electromagnet having coil means and a core, a thermocouple connected to said coil means for producing a thermoelectric current therein, an armamature into cooperation with the core, and a second switch for opening said circuit during the resetting operation and until the pilot burner is lighted and heats the thermo-couple to a temperature to maintain said thermoelectric device reset.

7. In combination, an electric circuit, a switch in said circuit, a thermoelectric device controlling said switch and comprising an electromagnet having coil means and a core, an armature, a thermo-couple connected to said coil means, means for resetting said armature against said core, and means for opening said circuit during the resetting operation.

8. In combination, an electric circuit, a switch in said circuit, a thermoelectric device controlling said switch, said thermoelectric device comprising an electromagnet having coil means and a core, an armature, a housing for said thermoelectric device, a thermo-couple connected to said coil means for producing athermoelectric current therein to, hold said armature against said core, means for resetting the armature into cooperation with the core, a closure cap for said resetting means and having removable attachment to said housing, contact means in said "circuit, and cooperating contact means carried by said cap and engageable with and disengageable from said first contact means upon application of the cap to said housing and removal of said cap from said housing.

9. A thermoelectric device comprising an electromagnet having coil means and a core, an armature, a stem carried by said armature, an electric circuit, a switch member carried by said stem for'controlling said circuit, a thermocouple connected to said coil means for producing a thermoelectric current therein to hold said armature against said core, means for resetting said armature into cooperation with the core, an upper hood member, a lower housing member, contacts in said circuit, said contacts being carrier by said lower housing member and insulated from each other, a closure cap for said resetting means and having removable attachment to said housing member, and a contact carried by said cap for bridging said first contacts when said cap is applied to said lower housing member and opening the circuit between said first contacts when said cap is removed.

10. In combination, a fluid supply conduit, an electromagnet comprising a magnetic frame and a coil, an armature, a thermo-couple connected to said coil for producing a thermoelectric current in said coil 'to develop magnetism in said magnetic frame for holding said armature against said frame, said armature separating.

from said magnetic frame when said coil is deenergized, electrically operated valve means havtric circuit for said electrically operated valve means. 1 g i a 11. In combination, a main burner, a fuel supply line for said burner, a pilot burner for said main burner, an electromagnet comprising a magnetic frame and a coil, an armature, a thermo-couple in proximity to the pilot burner and connected to said coil for energizing said electromagnet by the heat of the pilot burner to hold said armature against the magnetic frame of said electromagnet, said armature separating from said magnetic frame when said electromagnet is deenergized, electrically operated valve means having an electric circuit controlled by said armature said electrically operated valve means being disposed in said fuel supply line for controlling the supply of fuel through said line, a reset stem member for resetting said armature against said magnetic frame, a closure cap memberfor said reset stem member, and means controlled by said closure cap member for controlling the electric circuit for said electrically operated valve means.

12. In combination, a fluid supply conduit, a valve for controlling the supply of fluid through said conduit, a movable armature operable to control said valve, an electromagnet for said armature, a thermo-couple connected to said electromagnet for energizing said electromagnet,

means for resetting said armature with respect shut off the supply'of fluid through said conduit during the resetting operation.

13. In combination, a main burner, a fuel supply line for said burner, a pilot burner for said main burner, valve means in said fuel supply line for controlling the supply of fuel through said line, a movable armature operable to control said valve, an electromagnet for said armature, a thermo-couple in proximity to the pilot burner and connected. to saidelectromagnet for energizing. said electromagnet by the heat of the pilot burner, means for resetting said armature with respect to said electromagnet, and means operable to shut off the supply of fuel through said fuel supply line during the resetting operation.

14. In combination, a fluid supply conduit, an electrically operated valve in said conduit, an electric circuit for said valve, a switch in said circuit, an electromagnet, a thermo-couple connected to said electromagnet for energizing said electromagnet, an armature adapted to be held to-said electromagnet upon energization thereof and connected to the switchto hold said switch closed when said electromagnet is energized, said armature separating from said electromagnet and opening said switch when said electromagnet is deenergized, means for resetting the armature against said electromagnet, and means for opening said electric circuit during the resetting operation.

15. In combination, a fluid supply conduit, an electrically operated valve in said conduit, an electric circuit for said valve, a switch in said circuit, an electromagnet, a thermo-couple connected to said electromagnet for energizing said electromagnet, an armature adapted to be held to said electromagnet upon energization thereof and Connected to the switch to hold said switch closed when said electromagnet is energized, said armature separating from said electromagnet and opening said switch when said electromagnet is deenergized, means for resetting the 'armature against said electromagnet, a closure cap for said resetting means, and cooperating contact means in said electric circuit and on said closure cap for opening said circuit when said cap is removed for access to said resetting means and closing said circuit when said cap is in position enclosing said resetting means.

16. In combination, a burner, a fuel supply line, a thermo-couple in proximity to said burner, a thermoelectric device comprising a magnetic frame, a coil connected to said thermo-coup pie for setting up a magnetic field in said magnetic frame by the action of said burner on said thermo-couple, an electrically operated valve in said fuel supply line, an electric circuit for said valve, a switch in said circuit, an armature ;adapted to be held to said magnetic frame by the magnetic field set up therein and connected to said switch to hold said switch closed when said coil is energized, said armature separating from said magnetic frame and opening said switch when said coil is deenergized, means for resetting the armature against said magnetic frame. and for opening said electric circuit during the resetting operation, a closure cap for said Disclaimer 2,183,827 .John H. Thornbery, Milwaukee, Wis. THERMOELECTRIC SAFETY SWITCH v AND THE LIKE. Patent dated Dec. 19, 1939. Disclaimer filed May 26, 1949, by the assignee, Milwaukee Gas Specialty Company, the inventor assenting.

Hereby enters this disclaimer to claims 12 and 13 of said patent.

[Ofiicial Gazette June 21, 1.949.]

Disclaimer 2,183,827 .John H. Thornbery, Milwaukee, Wis. THERMOELECTRIC SAFETY Swrrcn AND THE LIKE. Patent dated Dec. 19, 1939. Disclaimer filed May 26, 1949, by the assignee, Milwaukee Gas Specialty Company, the inventor assenting. Hereby enters this disclaimer to claims 12 and 13 of said patent.

[Oflicial Gazette June 21, 1949.]

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