US2533625A - Safety control system for fuel burners - Google Patents

Description

Dec. 12, i950 W. A. RAY 2,533,625

SAFETY CONTROL SYSTEM FOR FUEL BURNERS Filed July 5, 1947 2 Sheets-Sheet l i2, 1950 W. A. RAY l 233925 SAFETY CONTROL SYSTEM FOR FUEL BURNERS Filed July 5, 1947 2 SheeQS-Shee 2 'ASME Patented Dec. 12, 1950 SAFETY CONTROL SYSTEM FOB FUEL BURNERS William A. Bay, North Hollywood, Calif., assigner to General Controls Co., a corporation of California Application July 5, 1947, Serial No. 759,034

(Cl. 15S-117.1)

19 Claims.

This invention relates to a system for controlling one or more fuel burners, such as the gas burners of a kitchen range, or of a gas heated clothes drier. l

In any such intallation, it is common to provide a number of pilot lights; for example, in a kitchen range of the modern type, there is at least one pilot for the top burners, and a pilot for the oven.

It is one of the objects of this invention to provide a system in which the pilots reman extinguished until it is desired to ignite the corresponding burner or burners, so that no fuel iS used or heat generated While the system is inactive.

It is another object of this invention to provide a system of this character in which the conrols are in the form of electrical push buttons. Ensurance against passage of fuel until after the pilot burner is lighted is effected in a simple manner, and constitutes still another object of this invention.

It is still another object' of this invention to provide a safety or shut-off valve that interrupts all flow of fuel to the burners until, by operation of the push-button, the plot burnersv are ignited.

Itis still another object of this invention to simplify the system by providing a single safety control, actuated by a single circuit controller, for causing ignition of any one or more of the burners. For this purpose, the pilot burners are all simultaneously ignited by operation of the circuit controller, but only those main burners are ignited for which the corresponding manually operated valve had been previously opened. Of course passage of fuel to these burners is interrupted by the safety or shut-off valve until it is assured that the pilot burners are ignited.

This invention possesses many other advantages, and has other objects which maybe made more clearly apparent from a consideration of one embodiment of the invention. For this purpose there is shown a form in the drawings accompanying and forming part of the present specification. The form will now be described in detail illustrating the general principles of the invention; but it is to be understood that this detailed description is not to be taken in a limiting sense, since the scope of this invention is.

best defined by the appended claims.

Referring to the drawings: y Figure 1 is a pictorial view, mainly diagrammatic, of a kitchen range in which the system of the invention is employed;

Fig. 2 is a wiring diagram of a system embodying the invention; y

Fig. 3 is an enlarged view of one of the pilot burners and its associated electrodes; Fig. 4 is a plan view of the control mechanism utilized in connection with the system;

Fig. 5 is a sectional view, taken along a plane corresponding to line 5-5 of Fig. 4;

Fig. 6 is a view similar to Fig. 5, but illustrating another stage of operation of the control mechanism; and y Fig. I is a view similar to Fig. 5, but showing a further stage of operation.

Although, in the present instance, a kitchen range I is illustrated in Fig. l, the invention may be embodied in other types of apparatus in which liquid or gaseous fuel burners are utilized.

In the present instance, top burners 2 are illustrated, as well as an oven 3, the burner of which is not shown. A common pilot light l is shown the oven burnerv may be controlled by a burner valve 1. Only the control handles for these burners are shown, since these are well known and requre no further explanation. 'Ihey may be adjusted manually or otherwise to obtain the desired degree of heating.

A safety valve 8 (Figs. 2, 5, 6, and 7) is interposed between the source of fuel, and all of the burners, including the oven burner. Thus, the conduit 9 leads to an appropriate source of gaseous fuel and connects to the inlet of the valve I. The outlet conduit I0 is arranged to supply fuel to all of the burners.

'I'he pilot flames l and 5 are caused to burn at the outlets of the pilot flame burners I2 and I3 (Fig. 2). These burners I2 and I3 are shown as supplied through a common plot burner valve I4 located in a conduit i5 leading to the conduit 9.

As shown most clearly in Figs. 5, 6, and 7, the safety valve l and the pilot burner valve Il may be housed integrally in a common casing ICI.

The safety valve 8 is shown as including a closure I6 mounted on an axially movable stem I1. The closure member I8 is urged or biased toward its seat, as by the aid of a compression spring Il, to interrupt the ow of fuel to the burners.'v The 'stem |1 is shown as appropriately guided through a sealing nut I9, and has a reduced neck extending above the casing |55, and terminates in a collar |06.

The pilot valve structure |4 is quite similar to that of the safety valve structure. It is` provided with a closure member 2| biased to closing position by a compression spring 22. The closure member 2| is mounted on an axially movable stem 23 guided in the sealing nut 24. It, too, has a neck portion 25 for moving the stem.

The arrangement is such that, when a start button 26 is urged inwardly the pilot burner valve |4 is opened, and igniters such as spark pro- .ducers 36, 31 (Figs. 2 and 3) for both of the pilot burners are energized electrically. This start button 26 may be appropriately guided adjacent the front of the range and is shown as biased to inactive position by a compression spring 21. This compression spring urges the button 26 toward the left, as viewed in Figs. 4, 5, and 6, as by engaging the right-hand side of a collar 28 attached to the button 26. The button 26 may havea corresponding collar 29 limiting movement of the button to the left. The right-hand end of` the springengages the interior wall of a shell 30 formed to receive the button.

The button 26 Acarries a movable member 3| which is urged toward the right as the button 26 is moved to the right. This movable member 3| is shown a`s a at plate (Figs. 4, 5, 6, and v'7).

It is provided with apertures 32 and 33.\ Depend- 54 at its opposite edges. Slot 53 thus forms the end .projections 55 and 56, shown most clearly in Fig 4.

The slot 53 serves. with the opening 32, to accommodate a compression spring 51 that is interposed between the members 3| and 5| and appropriately guided thereon. This compression spring 51 urges the contacts 46 and 41 apart.

yThese contacts are normally separated while the can move in unison therewith unless there be an ing from the left-hand edge of the right-hand aperture 33 is an operating member or actuator 34. This operating member 34, when the button 26 is pressed inwardly, serves to engage one arm of a bell crank lever 35. Ihe other arm of the bell crank lever is engaged yaround the neck 25. Clockwise rotation of the bell crank lever 35 by inward movement of the member 3| thus serves to lift the valve stem 23 against the force of spring 22, and the pilot burners I2 and I3 are supplied with fuel.` This position is shown in Fig. 6.

At the same time, an ignition circuit is closed to ignite the burners |2 and |3 and to cause the llames 4 and 5 to be in existence. Igniters 36 and 31 for these burners are indicated in 2, and may be spark generators supplied with electrical energy from a step-up transformer 38. The p rimary winding 39 of thistransformer is controlled in a manner to be hereinafter described. The secondary winding 40 is shown as having a central ground connection 4|. When the circuit for primary winding 39 is closed, electrical energy is supplied to the igniter 31- through` the following circuit: ground 4|, the-upper half of Winding 40, conductor 42, igniter 31, and ground connection 43. $imilarly, the circuit for igniter 36 includes ground connection 4|, the lower` half of winding 4U, connection 44. igniter 36, and ground connection 45.

'Ihe circuit for the primary winding 39 is controlled by the aid of a pair of relatively movable contacts 46 and 41 which are caused to be engaged only when the safety valve 8 is closed. For this-purpose contact 46 is insulated from and carried by an arm 49 mounted on the upper side of movable member 3|. The contact 41 is similarly mounted on an arm 50 which' is supported on another member 5|. This contact 5| is arranged on top of the member 3| and is movable therewith. Member 5| is guided for this movement by ears 52 formed on the edges of the member 3|. Member 5| is provided with slots 53 and abutment preventingmovement of the member 5|. This abutment is effective only while the safety valve 6 is closed. When the abutment is effective, the movement of member 5| is stopped. and the contacts 46 and 41 engage, as in the position of Fig. 6. lIn this position the igniters 36 and 31 are operated, and the pilot burners |2 and I3 are ignited.

The abutment in this case is in the form of a bar 58 having projections that extend in the path of the projections 55 and 56 of the member 5|. This bar 58 is shown as supported upon a bell crank lever 59 which is urged in a counterclockwise direction by aid of a coil spring 66. The pivot pin 6| serves to support the lever 59. The lower arm 62 of the lever 59 is slotted to receive the reduced portion 20 ofstem I1. Clockwise movement of the lever 59 thus serves to lift the stem I1 and to open the safety valve 8. This position is indicated in Fig. 7.

In the closed position of the safety valve 8, the level' 59 is in such position that the abutment 58 is eiective to stop movement of the member 5|. Accordingly, as the push button 26 is urged inwardly, movement of contact 41 is stopped, while movement of contact 46 continues; and. ultimately. the contacts close in the position of Fig. 6.

The push button 26 is maintained depressed by the hand of the user for a short period until the pilot burners |2 and `I3 are ignited.I As soon as the pilot naines 4 and 5 are in existence, the lever 59 is automatically moved in a clockwise direction to the position of Fig. 7, and the abutment 58 moves out of the path of member 5|. Accordingly, the compression spring 51 can expand to the position shown in Fig. 7, urging the contact 41 away from contact 46 and de-energizing the igniters. 'At 'the same time the safety valve 8 is opened and fuel can then pass to the main burners. The control of the main burner llames can be effected by operation of the burner valves 6 and 1.

In order to move the bell vcrank lever 59 to the opening position of Fig. 7, use is made of an electromagnet 63 which has a core 64. The lever 59 is made from magnetic material, so that it is attracted to core 64 when coil 63 is energized. Energization of the coil 63 is de-i pendent upon the existence of the pilot ames 4 and 5; and itis only when both of these llames are in existence that coil 63 is.energized.

The arm 62'is also provided with an upturned latch 65 that is adapted to engage the righthand edge of the aperture 33 (Fig. 7). In this the pilot burner valve I4 retained in openposition by the actuator 84. l l

To interrupt the supply of fuel to the burners, a stop button 88 (Figs. 1 and 2) may be utilizedy to interrupt the circuit for the coil 88. Under such circumstances, lever 58 is urged in a counter-clockwise direction by spring 88, and the latch 85 releases .the member 8|. Compression spring 21 returns the b'utton 28 to the inactive position of Fig. 5.

'I'he control circuit for the coil 88 includes the thermionic emission device 81 (Fig. 2). This thermionic emission device is shown as having a illamentary cathode 88, a control electrode 88, and an anode 18. The electrical energy is supplied to the thermionic device and its associated circuits 12 through a step-up transformer 1|. plied from the mains 13, to which the primary winding -38 of the ignition transformer 38 is also connected. The secondary winding 14 is shown as tapped at several places to supply appropriate voltages to the electrodes of the thermionic device 81. Thus, the filament 88 is supplied through a section 15 of the transformer winding 14.

'I'he output circuit of the device 81 includes plate 10, connection 18, and stop button contacts 11 capable of being operated by pushing the stop button 88. The circuit then continues through a connection 18, coil 83, and connection 19 to the lower terminal of the winding 14.

v .,which the lower terminal 14 is positive, to cause The primary winding 12 is shown as supflow of an operative current through the anode or output circuit traced hereinabove.

Assurance is provided that, in the event of grounding of any of the electrodes 82 or 81, the circuits are de-energized to return the system to the inactive condition. For this purpose tubular metallic shields 8| and 82 are provided surrounding the conductors 82 and 81 in which these conductors are insulated and supported. The shields are both connected to the upper terminal of winding 14. Accordingly, it either of the electrodes 82 or 81 is grounded, the control electrode 89 would be maintained at a potential negative with respect to the cathode 88.

The manner in which the spark igniters 88 and 81 are supported. as well as the manner in which the shields and electrodes are supported, is shown most clearly in Fig. 3. Thus. the burner l2, which provides the pilot flame 4, is shown as provided with a metal bracket 88. This bracket has an arm 84 in which the spark generator 81, forming Since current passes through this circuit only v to move the lever 59 to open the safety valve 8,

it is necessary that the potential of control electrode 59 be positive with respect to the filament 88. The input circuit including this control electrode comprises connection 8|, electrode 82 that extends into the flame 5, another electrode 88 also extending into the flame 5, a ground connection 85, and electrodes 88 and 81 extending into the flame 4. Electrode 81 is connected by the conductor 88 to a point 88 on winding 14 which is positive with respect to the filament 88 when the lower terminal of winding 14 is positive.

In this input circuit, advantage is taken of the conductivity of flames 4 and 5. When either of these flames 4 and 5 is not in existence, an open circuit is produced between the corresponding conductors 82, 83, or 88 and 8-1, and the control electrode 88 attains a negative potential with respect to the filament 88 throughv a resistance connection 98. Accordingly, when the input circuit is interrupted by failure of either flame 4 or 5, the electromagnet coil 83 releases the lever 59 to the position of Fig. 5, and the system is shut down.

The potential impressed on electrode 88 by resistor 88 can never cause flow of current through the output circuit since, when th upper terminal of winding 14 is positive (making controlelectrode 88 positive with respect to the cathode 88), the lower terminalv of winding 14 is negative and, therefore, the anode 18 is negative, and no space current can flow to it. It is only when the relative potentials of the winding terminals are as the igniter contacts 88, is supported. Another bracket 81 has threaded therein a hollow screw 88. This screw 88 has a head for clamping the electrode 88 in place (thereby grounding it on pilot burner I2). An insulation sleeve 88 passes through screw 88. and is provided with layers of insulation |88 through which the electrode 81 passes. This electrode in turn is connected to an insulated conductor I 8| over which the shield 82 is placed'.

The mode of operation of the system may now be summarized. In order to start operation of any of the burners 2, or the oven burner, from the inactive position shown in Figs. 4 and 5, any one of the manually operated valves 8. 1 may be opened. No gas flows, since the safety valve 8 is still closed. Now the starting button 28 may be depressed and held in depressed position until the coil 83 is energized, as hereinbefore stated. Depression of the button 28 causes the passage of fuel to the pilot burners I2 and I3 and their ignition by aid of the contacts 48 and 41.

As soon as coil 83 is energized, the lever 58 is attracted to the position of Fig. 7, permitting separation of contacts 48 and 41. This lever also latches the push button in operative position, maintaining the pilot burner valve |4 open. Gas can now flow to those main burners for which the manually operated valves 8 and 1 have been opened, and one or the other of the pilot flames serves to ignite these burners.

When it is desired to shut down the system, stop button 88 is depressed. 'I'his causes separa tion of the contacts 11, coil 83 is de-enrgized, and the system returns to the position of Fig. 5.

'I'he valve mechanism and control illustrated in Figs. 4, 5, 6, and '1 of this application are described and claimed in a divisional application Ser. No.' 184,143. filed September 11, 1950.

The inventor claims:

1. In a system of the character described: a plurality of main fuel burners; a plurality oi pilot burners; a. safety valve controlling the flow of fuel to all of the main burners; means for passing fuel to the pilot burners and for ignitiug the pilot burners; and means operating in re.

spouse to the ignition of all of the pilot burners for maintaining the supply of fuel to the pilot -burners and for opening the safety valve.

2, In a system of the character described: a

plurality of main fuel burners; a plurality of pilot burners for igniting their respective main burners; individual control valves for each of the main burners; a safety valve for interrupting the flow of fuel to all of the main burners; a common pilot burner valve for all of the pilot burners; igniters for the pilot burners; means for temporarily opening the pilot burner valve and for operating the igniters;'and means responsive to the ignition of all of the pilot flames for maintaining the pilot burner valve open and for opening the safety valve.

3. In a system of the character described: a plurality of main fuel burners; a plurality of pilot burners for igniting their respective main burners; individual control valves for each of the main burners; a safety valve for interrupting the iiow of fuel to all of the main burners; y

a common pilot burner valve for all of the pilot burners; igniters for the pilot burners; means for temporarily opening the pilot burner valve 'and for operating the igniters; and means responsive to the ignition of all of the pilot ames for maintaining the pilot burner valve open and for opening the safety valve, comprising electrodes extending into the pilot flames, said electrodes being arranged so that they form a series circuit with the flames.

4. In a system of the character described: a main fuel burner; a pilot burner; an electrically energized igniter for the pilot burner; means for energizing said igniter and for passing fuel to the pilot burner, said means including a pair of relatively movable members each having a contact which when engaged, energizes the igniter, as well as means for obstructing movement of one of the members when the other member ismoved;

y and means responsive to the existence of the pilot name for maintaining said other member in position to permit passage of fuel to the pilot burner, and for moving said obstructing means away from said first member, for de-energizing the igniter.

5. In a system of the character described: a main fuel burner; a pilot burner; an electrically energized igniter for the main burner; a first and a second member relatively movable with respect to each other; means urging said members apart; contacts carried respectively by said memlbers which are engaged when the rst membery is moved relatively to the second member for energizing the igniter; means for moving the first member; means operated by movement of said first member to pass fuel to the pilot burner; means forming an abutment for the second member for engaging the contacts when the first member is moved; and means responsive to the existence of a pilot flame for'removing the abutment and for holding the first member in fuel passing position.

6. In a system of the character described: a main fuel burner; a pilot burner; a safety valve controlling the ow of fuel to the main burner; an electrically energized igniter for the pilot burner; means for energizing said igniter and for passing fuel to the pilot burner, said means including a pair of relatively movable members each having a contact which, when engaged, energizes the igniter, aswell as means obstructing movement of one of the members when the other member is moved; and means responsive of fuel to the pilot burner, and for moving said obstructing means away from saidflrst member, and for opening said safety valve.

7. In a system of the character described: va main fuel burner; a pilot burner; a safety valve controlling the iiow of fuel to the main burner; an electrically energized igniter for the main burner; a first and a second member relatively movable with respect to each other; means urging saidmembers apart; contacts carried respectively by said members Which are engaged when the first member is moved relatively to the sec-` ond member, for energizing the igniter; meansl for moving the ilrst member; means operated by movement of said first member to pass fuel to the pilot burner; means forming anabutment for the second member for engaging the contacts when the rst member is moved; and means responsive `to the existence of, a pilot name for removing the abutment and for holding the first member in fuel passing position and for opening the safety valve.

8. In a system of the character described: a plurality of main fuel burners; a plurality of pilot burners for the main burners; a safety valve controlling the ilow. of fuel to all the main burners; a first and a second member relatively movable with respect to veach other; means urging said members apart; contacts carried respectively by said members which are engaged when the first member is moved relatively to the second member, for energizing the igniter; means for moving the first member; means operated byv movement of said first member to pass fuel to al1 the pilot burners; means forming an abutment for the second member for engaging the contacts when the rst member is moved; and means responsive to the existence of a pilot flame at all of the pilot burners, for removing the abutment and for holding the first member in fuel passing position and for opening the safety valve.

9. In a system of the character described:l a plurality of main fuel burners; a plurality of pilot burners for the main burners; a safety valve controlling the 4flow of fuel to all the main burners; a rst and a second member relatively movable with respect to each other; means urging said members apart; contacts carried respectively by said members which ,areengaged when the first member is moved relatively to the second member, for energizing the igniter; means .for moving the first member; means operated by movement of said first member to pass fuel to all thepilot burners; means forming an abutment for the second member for engaging the contacts when the first ,member is moved; and means responsive to the existence of a pilot flame at all of the pilot burners, for removing the abutment and for holding the first member in fuel passing position and for opening the safety valve, comprising electrodes located in the pilot ames and arranged in a series circuit.

10. In a system of the character described: a main fuel burner; a pilot burner; a safety valve for controlling the flow of fuelto the main burner; means biasing said safety valve to-closed position; means for temporarily passing fuel to the pilot burner and for igniting the pilot burner; means for urging the said fueling passing means constantly to inactive position; means responsive to the existence of a pilot flame for latching said fuel passing means in `active position and releasing said fuel passing means when the pilot flame is extinguished, said responsive means also operating to open said safety valve and to permit said safety valve to closeA when the pilot flame is extinguished.

1l. In a system of the character described: a plurality of main fuel burners; a plurality of pilot burners for igniting their respective main burners; individual control valves for each of the main burners; a safetyl valve for interrupting the ow of fuel to all of the main burners; a common pilot burner valve for all of the pilot burners; igniters for the pilot burners; means for temporarily opening the pilot burner valve and for operating the igniters; means urging the safety valve to closed position; means urging said pilot burner valve opening means in a direction to cause the pilot burner valve to close; and means responsive to the ignition of all of the pilot `flames for latching the pilot burner valve opening means in fuel passing position and for opening the safety valve, said latching means being released when any of the pilot flames is extinguished.

12. In a system of the character described: a plurality ofmain fuel burners; a plurality of pilot burners for igniting their respective main burners; individual control valves for each of the main burners; a safety valve for interrupting the flow of fuel to all of the main'burners; a common pilot burner valve for all of the pilot burners; igniters for the pilot burners; means for temporarily opening the pilot burner valve and for operating the igniters; means urging the safety valve to closed position; means urging said pilot burner valve opening means in a direction to cause the pilot burner valve to close; and means responsive to the ignition of all of the pilot flames for latching the pilot burner valve opening means in fuel passing position and for opening the safety valve, said latching means being released when any of the pilot flames is extinguished, said responsive means including electrodes extending into the pilot flames and arranged in series.

13` In a system of thecharacter described: a main fuel burner; a. pilot burner; a safety valve controlling the flow of fuel to the main burner; an electrically energized igniter for the main burner: a first anda second member relatively movable with respect to each other; means urging said members apart; contacts carried respectively by said members which are engaged when the first member is moved relatively to the 1 second member, for energizing the igniter; means for moving the first member; means biasing said first member to inactive position; means biasing the safety valve to closed position; means operated by movement of said first member to pass fuel to the pilot burner; means forming an abutment for the second member for engaging the contacts when the flrst member is moved; and means responsive to the ignition of the pilot flame for latching Vthe first member in fuel passing position and for opening the safety valve, said latching means being released when the pilot flame is extinguished.

14. In a system of the character described: a plurality of main fuel burners; a plurality of pilot burners for the main burners; a safety valve controlling the flow of fuel to all the main burners; a first and a second member relatively movable with respect to each other; means urging said members apart; contacts carried respectively by said members which are engaged when the first member is moved relatively to the ,second member, for energizing the igniter;

means for moving the first member; means operated by movement of said first member to pass fuel-to all the pilot burners; means forming an abutment for the second member for engaging the contacts when the first member is moved; means biasing said first member to inactive position; means biasing the safety valve to closed position; and means responsive to the ignition of all of the pilot flames for latching the first member in fuel passing position and for opening the safety valve, said latching means being released when any of the pilot names is extinguished.

15. In a system of the character described: a plurality of main fuel burners; a plurality of pilot burners; a safety valve controlling the flow of fuel to all of the main burners; means biasing said safety valve to closed position; means for passing fuel to the pilot burners and for igniting the pilot burners while said safety valve is in closed position; means operating in response to the ignition of the pilot burners for maintaining the supply of fuel to the pilot burners and for opening the safety valve; said last-mentioned means operating in response to pilot flame failure at any one of said pilot burners to effect closing of said safety valve.

16. In a system of the character described: a plurality of main fuel burners; .a plurality of pilot burners; a safety valve controlling the flowv of fuel to all of the main burners; means biasing said safetyl valve to closed position; means for passing fuel to the pilot burners while said safety valve is in closed position; means operating in response to the existence of names at the pilot burners for maintaining the supply of fuel to the pilot burners and for opening the safety valve; said last-mentioned means operating in response to pilot flame failure at any one of said pilot burners to effect closing of said safety valve.

17. In a system of the character described: means for burning fuel; a plurality of pilot burners; a safety valve controlling the flow of fuel to said means; means biasing said safety valve to closed position; means for passing fuel to the pilot burners while said safety valve is in closed position; means operating in response to the existence of flames at said pilot burners for maintaining the supply of fuel to the pilot burners and for opening the safety valve; said last-mentioned means operating in response to pilot flame failure at any one of said pilot burners to effect closing of said safety valve.

18. In a system of the character described: a plurality of main fuel burners; a plurality of pilot burners; a safety valve controlling the flow of fuel to all of the main burners; means biasing said safety valve to closed position; means for passing fuel to the pilot burners and for igniting the pilot burners while said safety valve is in closed position; a pilot burner valve controlling the flow of fuel through said means; means biasing said pilot burner valve to closed position; means operating in response to the ignition of the pilot burners for maintaining the supply of fuel to the pilot burners and for opening the safety valve; said last-mentioned means operating in response to pilot flame failure at any one of said pilot burners to effect closing of said safety valve and said pilot burner valve.

11 19. In a system' ofthe character described.:

means for burning fuel; a plurality of pilot A `burners; a safety valve controlling the flow of ilame failure at any one of said pilot burners to eii'eet closing of said safety valve and 'said pilot burner valve.

WILLIAM` A. RAY.

REFERENCES CITED The following references are of record in the file of this patent: I 1 UNITED STATES lATENTS n Number Name Date y2,183,855- Mansw Dec. 19, 1939 2,275,657 Wetzel Mar. 10, 1942

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