US2351277A

US2351277A - Safety device

Info

Publication number: US2351277A
Application number: US336090A
Authority: US
Inventors: Harold A Mantz
Original assignee: Milwaukee Gas Specialty Co
Current assignee: Milwaukee Gas Specialty Co
Priority date: 1940-05-20
Filing date: 1940-05-20
Publication date: 1944-06-13
Anticipated expiration: 1961-06-13

Description

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H. A, MANTz SAFETY DEVICE Filed May 2o, 1940 Jane' 13, 1944.

Patented June 13, 1944 U N 1T E orales SAFETY DEVCE Application May 20, 1940. Serial No. 336,090

(Cl. 15S-117.1)

8 Claims.

'I'his invention relates to safety devices for gas or other fuel burners.

Burners of this sort are subject at times to what is known in the art as a flash-back. In the case of a gas burner, for example, the gas is usually mixed with air in a mixing chamber adjacent the burner, and the combustible mixture of gas and air is conducted to the burner where it is ignited by a pilot light. At times, the flame may flash back and the gas fuel burns in the chamber where the mixture of air and gas normally takes place. Where such a flash-back occurs, the gas often burns with insufficient oxygen, resulting in the production of a relatively large quantity of carbon monoxide, which is highly objectionable, and even dangerous, particularly in the absence ofy adequate flue connections.

One of the main objects of the present invention is to provide improved means in combination with al gas or other fuel burner, which means will operate automatically in the case of a flashback to shut off the supply of fuel to the burner.

Another object of the invention is to provide improved means responsive to thermal conditions in the mixing chamber or at the outlet from which the fuel for the main burner is delivered for controlling the supply of fuel to the burner, and particularly for shutting off the supply of fuel to the burner in the event of an abnormal temperature at this location.

Another and more specific object of the invention is to provide in combination with a thermocouple placed in position to be heated by the pilot flame and connected to an electromagnet which is operative to maintain a valve in the fuel supply pipe leadlng to the burner open as long as the pilot flame is burning, a second thermocouple in position to be exposed to heat resulting from a flash-back and arranged wholly or par tially to counteract or neutralize the action of the first thermocouple to release the valve for movement to closed position when a flash-back occurs.

Further objects and the features and advantages of the invention will be apparent from tion has been shown more or less schematically as embodied in a manner automatically to close a valve in a fuel supply pipe leading to a burner in case of a dash-back, and also when the pilot light for the burner goes out.

Referring now to Figure 1 of the drawing, a gas or other fuel burner of any suitable or preferred type is conventionally illustrated at I The burner i0 may be the burner of a room or space heater, water heater, iloor furnace, range. or any other burner. A gas or other fuel supply pipe II leads to the burner i0 for the delivery -of gas or other fuel thereto-for example, through the outlet or delivery orifice i2 into the mixing chamber i3 in which the fuel is mixed with air which enters the mixing chamber through one or more ports M. The combustible mixture of gas and air passes from the mixing chamber i3 through a conduit i5 to the burner ill where it is delivered through the ports of the burner and ignited by a pilot burner i6 in juxtaposition to the main burner.

The safety shuto valve I8 is incorporated in the fuel supply pipe Ii. The particular form of the valve i8 may vary widely within the scope of the present invention. The particular valve shown more or less schematically in the drawing has an inlet i9 and an outlet 20 with a valve opening 2l for placing the inlet in communication with the outlet. A valve seat 22 is provided at one end of the valve opening 2l and, in the illustrated embodiment of the invention, a second valve seat 23 is provided at the opposite end of the valve opening. The pilot burner i6 is shown as supplied with fuel by a pilot supply pipe 25 shown as connected at 26 to the interior oi' the valve i8 between the

valve seats

22 and 23, it being understood that this may be varied within the scope of the present invention.

The valve i8 is adapted to be closed by a valve member 2B to shut oil the supply of fuel to the main burner and also, preferably, the supply of fuel to the pilot burner as shown in the drawing. The electromagnet 28 comprises a magnet frame 30 shown as of generally U-shaped form, although this may vary. The valve member 28 is connected by a stem 32 to an armature 33. When the armature 33'is placed in attracted position against the pole ends of the magnet frame 3D and the electromagnetis energized, as will presently appear, the electromagnet operates to hold the armature 33 in attracted position and the valve member 28 open for the supply of fuel to the main burner and also to the pilot burner i6. When the electromagnet 29 is deenergized, a

as will hereinafter appear.

spring, indicated at 38, actuates the valve member 28 to closed position against the valve seat 22 to sh`-,ut off the supply of fuel to the main burner and the pilot burner.

The electromagnet 28 has an energizing coil 36 which, in Figure 1, is shown as surrounding one of the legs of the magnet frame 38. This, of course, may vary where the magnet frame is of other form, or where only one coil is provided, The energizing coil 36 is connected in circuit with the thermooouple 38. 'I'he thermooouple 38 is placed in position so that its thermojunction 38 will be heated by the pilot light when said pilot light is burning. The construction of the thermooouple may be similar to that disclosed in Oscar J. Leins Patent No. 2,126,564, granted August 9, 1938, or it may be of any other suitable-oi,` preferred form. One side of the energizing coil 36 is connected in oircuit with one of the thermooouple elements-for example, the outer thermooouple element 48- through a lead conductor 4I, and the other side of the coil 36 is connected in circuit with the other thermooouple element, namely the internal thermooouple element 42 of the particular thermooouple shown, through a lead conductor 43.

The outlet member 45, having the outlet or orifice I2 through which the fuel enters the mixing chamber I3 and which is shown of tubular form and as mounted on the adjacent end of the fuel supply pipe II, constitutes one of the dissimilar metallic thermooouple elements of a second thermooouple 48. The other metallic thermooouple element 41 of the thermooouple 48 is shown of annular form surrounding and spaced from the element 45. The thermooouple elements 45 and 41 extend into the mixing chamber I3, and the innen end of the outer element 4l is contracted and joined to the element 45 to form a thermojunotion 48. The thermojunction 48 is thus disposed so that it-is responsive to thermal conditions ,in the mixing chamber I3, or at the outlet I2, and, more particularly, so that it will be heated by the flash-back name 58 which burns at the outlet I2 in the case of a flash-back. Where there is no flash-back condition, of course the flame indicated in dotted lines at 58 is absent.- In the embodiment of the invention shown in Figure 1, the eleotromagnet 29 is shown as having a neutralizing coil 52 in addition to the energizing coil 36. The neutralizing coil 52 is shown as surrounding the other leg of the magnet frame 38 which, of course, may vary where the magnet frame is of other form, or where only one coil is employed. One side of the coil 52 is connected in circuit with the thermooouple element 45 through a lead conductor 54, and the other side of the coil 52 is connected in circuit with the other thermooouple element 4'I through a lead conductor 55. y

The heat of the pilot light on the thermooouple 38 energizes the electromagnet 28 sufolently to hold the armature 33 in attracted position and the valve 28 open, assuming of course that there is no flash-back flame as indicated at 58, when the armature 33 is engaged with the pole ends of the magnet frame, but this thermoelectrio current is not capable of moving the armature to attracted position and the valve member 28 to open position. Cooking means is therefore provided for actuating the armature 33 to attracted position and the valve member 28 to open position.

The cooking means comprises a cooking or reset stem 68 coaxial with the valve member 28 and extending outwardly from the valve body. The outer end of the cooking stem 88 has a cooking or reset button 8| mounted thereon. The cooking stem 68 also has a flow interrupter disk 62 which, when the cooking stem 88 is pressed inwardly in the cooking operation, seats upon the valve seat 23 to shut off the supply of fuel to the main burner. A ow interrupter disk spring is provided at 83, and upon seating of the disk 82 upon the seat '23 in the cooking operation, the cooking stem is adapted to continue in its inward movement through the flow interruptor disk to bring the armature 33 fully to attracted position and the valve member 28 fully to open position. A spring 64 interposed, for example, between the valve housing and thercooking button 6I returns the cooking stem to its outwardly projected position upon completion of the cooking operation.

To start the operation of the system, the following sequenoe is followed:

The cooking stem 88 is pressed inwardly to aotuate the valve member 28 to open position and the armature 33 to attracted position in contact with the pole `faces of the magnet frame 38. This allows the fuel to flow through the pilot connection at 26 and pilot supply pipe 25 to the pilot burner I6 where the same is ignited.;A The stem 68 is held in depressed position until the pilot flame has heated the thermooouple suiilciently to energize the eleotromagnet 28 so that it will hold the armature 33 attracted thereto and, thereby, the valve member 28 in open position. The flow interrupter disk 62 seats upon the valve seat 23 to shut off the flow of fuel to the main burner as long as the cooking stem 68 is depressed.

When the eleotromagnet is energized sumciently to hold the armature 33 in attracted position and the valve member 28 in open position, the lcooking stem 68 is released, thus allowing the flow interruptor disk 62 to return to open or normal operating position. Fuel then flows out through the outlet 28 and fuel supply pipe II to the main burner where it is ignited by the pilot burner I6. If the pilot burner is not lighted to produce the thermoeieotrlo current for holding the armature 33 in attracted position and the valve 28 open, the armature 33 will be actuated to retracted position and the valve member 28 to closed position upon release of the cooking stem 68. Also if, after being lighted, the pilot burner is extinguished, the armature 33 is released and the valve member 28 is actuated to closed position to shut oi the supply of fuel to the main burner and to the pilot burner.

Upon normal operating conditions, the temperature of the thermojunotion 48 is not high enough to set up the thermoelectrio current necessary sufiloienftly to neutralize the current set up .by the thermooouple 38, and the valve member 28 remains open as long as the pilot burner I8 is lighted. However, in the event of a flash-back with the pilot light burning, the flash-back flame, which then burns as indicated at 58, heats the i thermojunotion -48 and thereby sets up a thermoelectric current in the neutri'ilizingl coil 52. This current neutralizes the holding effect of the ourrent in the energizing coil 36 sufficiently to release the armature 33 and the valve member 28 is actuated to closed position to shut off the supply of fuel to the main burner and the pilot burner. Upon discontinuance of the ash-baok condition. the neutralizing action ceases to be effective, so that the system may be again set into operation by pressing the -cocking stem l8|) and lighting the pilot burner, as already described. l

In the embodiment of the invention shown in Figure 2, the electromagnet 28', instead of having an energizing coil and a neutralizing coil, has

only one coil 10 shown as wound around the legs of the magnet frame 30', it being understood that the coil 10 .may be otherwise arranged, particularly where the magnet frame is of a form other than that shown.

In this case, one side ci' the coil 10 is connected in circuit with one of the thermoeouple elements 40', 42 of the thermccouple 38' by e. lead conductor 1I. The other element oi the thermocouple 38 is connected in circuit with one of the thermocouple elements 45', 4l of the thermocouple 48. The other element of the thermocouple 4'6 is connected in circuit with theY other Y closed position.

Certain embodiments of the invention have been illustrated in the accompanying drawing, but

it is to be expressly understood that said drawing is for purposes of illustration only and is not to be construed as a deiinition oi the limits or scope of the invention, reference being had to the appended claims for that purpose.

I claim:

1. In a flash-back safety device for gas burners, the combination with a gas burner, a gas and air mixing chamber, a conduit for conveying the gas and air mixture from said mixing chamber to the burner, a tubular Jet member constituting one of the elements oi' a thermoelectric generator and extending through a wall of said mixing chamber with its inner end disposed within said mixing chamber and its outer end disposed outside said chamber, a fuel supply pipe connected to the outer end of said jet member for delivering gas into said mixing chamberl through said jet member, a second thermocouple element extending through the wall of said mixing chamber .and joined inside said chamber to said tubular iet member to form a thermoiunction adapted to be heated by a flash-bach iiame, and thermoelectric conductors connected to said first and second mentioned thermocouple elements outside said mixing chamber.

2. In a flash-back safety device for gas burners, the combination with a gas burner, a gas and air mixing chamber, a conduit for conveying the gas and air mixture from said mixing chamber to the burner, a tubular Jet member constituting one of the elements of a thermoelectric generator and extending through a wall of said mixing chamber with its inner end disposed within said mixing chamber and its outer end disposed outside said chamber, a fuel supply pipe connected to the outer end of said iet member for delivering gas chamber to said tubular Jet member to form thermojuncticn adapted to be heated by a dashback dame, and thermoelectric conductors -connected to said tlrst and second mentioned thermo couple elements outside said mixing chamber.

3. In a dash-back safety device for gas burners, the combination with a main gas burner, a pilot burner in juxtaposition to said main burner, a gas and air mixing chamber, .a conduit i'or conveying the gas and air mixture from said mixing chamber to the main burner, a fuel supply pipe leading to said mixing chamber. a thermoelectric responsive valve in said iuel supply pipe and comprising a magnet frame and a pairv of operating lwindings, a thermocouple in position to be heated by said pilot burner and connected in circuit with one of said windings, and a second thermocouple Y, having a thermoiunction disposed within said mixing chamber and connected in circuit with the other winding to neutralize the action of said rst thermocouple when said second thermocouple is heated by a dash-back llame in said mixing chamber.

4. In a device oi the class described, the combination of a burner, a mixing chamber for mixing gas and air and supplying the mixture to said burner, a gas supply pipe for supplying gas to said gas and air mixing chamber, a thermoelectric responsive control valve in said gas supply pipe comprising a magnet frame and a pair of operating windings, a pilot burner, a thermocouple in position to be heated by said pilot burner and connected in circuit with one of said windings to maintain said thermoelectric responsive control valve in open vposition as long as said thermocouple is heated by the pilot burner, and a second thermocouple connected in circuit with the other Winding and having a hot junction disposed within said mixing chamber, said second thermocouple being normally deenergized and in position to be heated by a flash-back flame in the mixing chamber and adapted by energizing the winding connected therewith to neutralize the action of said rst thermocouple for movement of said thermoelectric responsive valve to closed position.

5. In a flash-back safety device for gas burners, the combination with a main gas burner, a pilot burner in `juxtaposition to said main burner, a gas and air mixing chamber, a conduit for conveyng the gas and air mixture from said mixing chamber to the main burner, a fuel supply pipe leading to said mixing chamber, a thermoeiectric responsive valve in said fuel supply pipe and into said mixing chamber through said iet memcomprising an electromagnet, a thermocouple in position to be heated by said pilot burner and connected in circuit with. said electromagnet, and a second thermocouple having a thermojunction disposed within said mixing chamber and connected in circuit with said electromagnet to neutralize the action of said first thermocouple when said second thermocouple is heated by a flashback flame in said mixing chamber.

6. In a fuel supply control system, a main burner, a fuel supply pipe connected to said burner, an automatic shutoff valve yieldingly urged closed for controlling flow of fuel to said burner, a pilot burner, means comprising an armature attached to said shutoff valve, and an electromagnet effective, when energized, for holding said shutoff valve open, said electromagnet comprising a magnet frame and a pair of windings each independent of the other, a. thermoelectric generator adapted to be heated by the flame of the pilot burner for energizing one o! said windings of said electromagnet to hold said armature in attracted position and said shutoff valve open, and a second thermoelectric generator disposed to be subjected to the heat of a ilame at the point of admission of fuel to said main burner, said second thermoelectric generator beingconnected in circuit with the other winding independently of the thermoelectric circuit including said first thermoelectric generator and acting, when heated by the latter ame, in opposition to said ilrst thermoelectric generator.

7. In combination, a gas burner comprising a gas and air mixing chamber having a wall provided with air inlet openings, a tubular jet member constituting one of the elements of a thermoelectric generator and extending through the wall of said chamber with its inner end disposed within said chamber and its outer end disposed outside said chamber, a fuel supply pipe connected to the outer end of said jet member for delivering gas into said chamber through said jet member, a second tubular thermoelectric element surrounding said jet member and extending through the Wall of said chamber with its inner end joined inside said chamber to said tubular jet member to form a thermojunction adapted to be heated by a ame in proximity to said jet member, an automatic shutoff valve yieldingly urged closed controlling flow of fuel to said jet member, an armature attached to said shutoff valve, and an electromagnet and energizing means therefor, said electromagnet being eiective, when energized, for holding said armature in attracted position and said shutoi'! valve open, said electromagnet comprising a magnet frame and a winding on said magnet frame and connected in circuit with the tubular elements of the therm electric generator.

8. In combination, an electroresponsive device having an operating position and a safety position, said electroresponsive device comprising a magnet frame, a first operating winding on said frame, a llame responsive thermocouple connected in closed circuit relation with said winding and eiective when heated by a flame to maintain said electroresponsive device in one of said positions. Va second winding on said frame, and a normally deenergized thermocouple connected in closed circuit relation with said second winding independently of said first winding and t0 neutralize the action of said rst thermocouple for enabling movement of said electroresponsive device to the other of its said positions when said second thermocouple is heated bya flame and thereby energized, the thermoelectric circuit including said ilrst winding and said rst thermocouple being normally free, when said ilrst thermocouple is heated by a flame, of the resistance of said second winding and said second thermocouple, whereby for al given E. M. F. generated by the heat of a flame on said rst thermocouple the holding action of the .electromagnet is maximum.

' HAROLD A. MAN'IZ.