US2513257A - Safety control and ignition system for gaseous fuel burners - Google Patents

Description

June 27, 1950 Y c. K. STROBEL 2,513,257

SAFETY CONTROL AND IGNITION SYSTEM FOR GASEOUS FUEL BURNER-S Filed Oct. 11, 1947 IN VEN TOR.

03601 105 4 Szmfiel.

HIS AYTTUM 1 Patented June 27, 1950 SAFETY CONTROL AND IGNITION SYSTEM FOR GASEOUS FUEL BURNERS Charles K. Strobe], Pittsburgh, Pa., assignor to Robertshaw-Fulton Controls Company, Youngwood, Pa., a corporation of Delaware Application October 11, 1947, Serial No. 779.338

This invention relates to safety control and ignition systems for gaseous fuel burners and, more particularly, to electrical systems therefor. In apparatus of this general character the flow of fuel to the main burner may be controlled by an electromagnetic control device which is energized by the current generated by a thermocouple or thermopile responsive to the heat of a flame at the pilot burner. Means are employed for placing the armature of the electromagnet in attracted position and the fuel control device in a flow permitting position, such operation being generally termed resetting. The means employed for resetting may be electrically operated from a source of current separate from that generated by the thermocouple. It is apparent that once the resetting operation is completed the current from this separate source is no longer required and the system may be left under the sole control of the thermoelectric current which is generated as long as the pilot burner produces a flame.

As disclosed in my copending application, Serial No. 580,672, filed March 2, 1945, now Patent No. 2,454,848, dated November 30, 1948, a timing device is used in such construction for automatically disconnecting the system from the external current supply upon completion of the resetting operation. The manual operation of the fuel control valve or thermostat to initiate the starting the kind described.

Another object of the invention is to reset an electromagnetic device by electrically operated means which are automatically rendered inoperative upon completion of the resetting operation.

Another object of the invention is to energize an electric igniter for the pilot burner from the same source of current as is used for energizing the resetting means.

Another object of the invention is to associate various elements of the control system in. compact units requiring a minimum number of operations to place the system in running condition.

Other objects and advantages will become apparent from the following description taken in connection with the accompanying drawing 5/Claims. (Cl. 158-1171) wherein is shown a schematic embodiment of the f safety control and ignition system of this invention in conjunction with the main and pilot burners of a gaseous fuel burning apparatus.

Referring more particularly to the drawing, a main burner I0 is supplied with fuel by a main fuel pipe I2 and the flow of fuel therein is under the separate control of a main control device, shown as a valve l4, and of a safety valve I6. The main valve I4 is manually operable by a handle is between the open and closed positions indicated by the legends On and "Off," respectively. A conduit 20 for supplying fuel from the main fuelpipe l2 to a pilot burner 22 is connected to the main valve l4 to receive a supply of fuel when the main valve I4 is in the On position. The main burner l0 and pilot burner 22 form the fuel burning' apparatus to which the safety control system is applied.

The safety valve I6 is an electromagnetic control means for the fuel flow in pipe l2 and is located between the main valve I 4 and the main burner I0. This valve I6 is provided with a partition 24 between the inlet and outlet openings and has a valve seat 25 with an opening 26 therethrough controlled by a reciprocable valve member 28. A valve stem 30 for the valve member 28 projects exteriorly of the safety valve l6 and carries a coil spring 32 serving to bias the valve member 28 toward the valve seat 25. An armature member 34 is carried on the exterior end of the valve stem 30 for cooperation with a horseshoe magnet 36. When the valve member 28 is in the open position shown in the drawing, the armature 34 is in its attracted position against the pole faces of the magnet 36. A suitable coil or winding 38 is providedfor the magnet 36 and connected by wires 42 and 44 in circuit with a thermoelectric generator shown as a thermocouple 40.

The thermocouple is located in proximity to the flame of the pilot burner 22 and is adapted to be heated thereby. As is known to those skilled in the art, the thermocouple 40 is a device capa-- ble of generating suflicient electrical energy when heated to retain the armature 34 against the pole faces of the magnet 36 but is incapable of actuating the armature 34 to this position. Accordingly, the safety valve I6 is provided with electromagnetic reset means now to be described. A reset stem 46 projects into the interior of the safety valve I6 on. the side of the partition 24 opposite the valve member 28 and is biased to an inoperative position outwardly of the safety valve 16 by a coil spring 48. The reset stem 46 and valve stem 38 are preferably in axial alignment and extend in opposite directions from the valve seat opening 26 which is axially aligned therewith.

The reset stem 46 carries a closure member 58 for the valve seat opening 26 and forming a flow interrupter for the safety valve I6. Formed on the reset stem 46 beyond the closure member 68 is a stem projection 52 which is engageable with a stem projection 54 formed on the valve stem 38 beyond the valve member 28. When the reset stem 46 is moved inwardly toward the valve seat 25 with the valve member 28 seated thereon, the engagement of the projections 52 and 54 will serve to force the valve member 28 away from the valve seat 25 and position the armature 84 in engagement with thepole faces of the magnet 36. At the same time, the closuremember 58 will overlie the valve seat opening 26 thus preventing flow of fuel through the main fuel pipe l2 to the main burner I8. It will be observed that fuel may flow in the conduit 28 to the pilot burner 22 during the period that the main burner flow is thus interrupted. It will be apparent, however, that the closure member 58 could be dispensed with and the resetting operation just described could be conducted while fuel flows simultaneously into the main fuel pipe l2 and pilot conduit 28.

The reset stem 46 is adapted to be moved inwardly against the bias of the spring 48 by the electromagnetic portion of the resetting means now to be described. This means comprises a transformer 56 combined with an electromagnetically operated plunger 58 which is reciprocable on an axis substantially parallel to the axis of the reset stem 46. A primary coil 68 of the transformer 56 serves to energize the electromagnet and attract the plunger 58 causing movement thereof from the full line position shown in the drawing to the broken line position also shown therein. The transformer 56 has a secondary coil 62 connected in circuit with an electric igniter Him the pilot burner 22 by means of wires 66 and 61. It will be apparent that the safety valve is and associated operating magnet 36, together with the transformer 56, could be combined in a unitary construction and that these elements have been shown schematically in the drawing for illustrative purposes without intending any limitation to the exact form shown.

The plunger 58 of the transformer 56 carries an operating arm 64 for an initially closed timeswitch means 66 in the form of a mercury switch adapted to be tilted to open position when the plunger 58 is in the broken line position. The time-switch means 66 is adapted to assume an open position only after the expiration of a predetermined period following operation thereof such as by providing a restricted exit for the mercury from one end of the tube to the other. In such devices an instantaneous reset characteristic is provided by an unrestricted inlet for the mercury flow back to its initial location. The usual electrodes 68, I8 are associated with the time-switch means 66 and cooperate with the mercury therein to close a circuit when the plunger 58 is in the full line position shown in the drawing. The operating arm 64 carries a connection in the form of a lateral bar I2 pivoted intermediate its ends, one of which overlies the reset stem 46 for moving the same downwardly against the bias of the coil spring 48 when the plunger 58 is moved to the broken line position shown in the drawing.

This invention is more particularly directed to an arrangement for actuating the time-switch means 66 automatically when the main fuel valve I4 is operated from Oil to On" position. Accordingly, a first initially open switch means 14 is provided and takes the form of a fixed contact I6 suitably mounted on insulation on the transformer 56 and adapted to cooperate with a relatively movable contact I8 suitably mounted on insulation on the plunger 68. Cooperable with the first switch means I4 is a second initially open switch means 88 in the form of a conventional push-button switch having a fixed contact 82 and a relatively movable contact 84 mounted upon a flexible switch arm 86 biased to a position for separating the contacts 82, 84. The flexible switch arm 86 extends into operative engagement with 9. lug 88 carried on the handle i8 of the main valve I4 opposite the indicia Ofi thereon. The arrangement is such that upon rotation of the handle I8 from the 0113" to the On" position the lug 88 will operatively engage the flexible switch arm 86 and cause engagement between the contacts 84, 82. This engagement is temporary only due to subsequent movement of the lug 88 past the flexible switch arm 86 in reaching the "On" position, whereupon the contacts 82, 84 become disengaged.

The system is shown in the normal running position with both the main burner l8 and the pilot burner 22 producing a flame and the main valve l4 in the On position. When the valve I4 is in the 05" position, the second switch means 88 is open as is the first switch means I4. The plunger 58 is in the released position shown in the drawing and the time-switch means 66 is in closed position as shown in the'drawing with the mercury bridging the electrodes 68, I8. In order to bring the system into the normal running operation described, the handle l8 of the main valve i4 is rotated counter-clockwise from the OiT" toward the On position shown in the drawing. Duringthis movement the lug 88 engages the flexible switch arm 86 and momentarily closes the contacts 82, 84. A circuit is thus established as follows: line wire 98, wire 82, primary coil 68, wire 84, contact I6, wire 86, contacts 82, 84, switch arm 86, wire 88, electrodes I8, 68, and wire I88 to line wire I82.

As will be apparent, this circuit places the primary coil 68 of the transformer 56, the contacts 82, 84 of the second switch means 88 and the electrodes 68, I8 of the time-switch means 66 in series with the source of electrical energy from line wires 88 and I 82. It will also be apparent that the portion of the circuit from contact 16, line wire 86, contacts 82, 84 and switch arm 86, is in parallel with or serves to short-circuit the first switch means I4 which has its contacts I6, I8 open in this initial or starting position.

The transformer 56 being energized in the foregoing circuit, the igniter 68 becomes energized through its described connection with the secondary 62. Moreover, the plunger 58 is moved from the released position shown in the drawing to the attracted or broken line position, whereupon the contacts I6, I8 of the switch means I4 become closed and the time switch means 66 becomes tilted for unbridging the electrodes 68, 18 after a predetermined delay.

when the rotation of the handle I8 is completed and the main valve l4 reaches the On position, then the ing 88 has moved past the flexible switch arm 86 whereupon disengagement of the contacts 82, 84 of the switch means 88 under bias of the flexible switch arm 86 has occurred. However, the series circuit Just traced remains closed but through the first switch means 14 due to the described closing of the contacts 16,-" thereof, it being noted that the electrodes 66, "are not yet unbridged by the mercury content of the time switch means 66. The operation of the plunger 58 to the broken line or attracted position has also served to rotate the pivoted bar 12 clockwise and thereby depress the end of the bar 12 which overlies the reset stem 46. The reset operation is now completed as the bias of the spring 46 is overcome. The closure member 56 thereupon operatively engages the partition 24 to close the opening 26 while the valve member 26 is moved to its open position. Moreover, the armature 34 is seated against the pole faces of the magnet 36. Thus, although the flow of fuel to the main burner I2 is cut-off, the pilot burner 22 receives fuel by way of conduit and this fuel is ignited by the igniter 63 which'is energized from the secondary 62 of the transformer 56.

At the end of the time-delay period of the switching means 66, which may be eighteen seconds from the initial turning on of the main valve It, the electrodes 68, Hi become unbridged by the mercury and the circuit previously traced is opened. The deenergizatlon of the primary winding 66 of the transformer 56 causes release of the plunger 58 and opening of the contacts I6, 18 of the switch means 14. While such release of the plunger 58 causes the time-switch means 66 to resume the tilted position as shown in the drawing. the bridging of the electrodes 66, 10 by the mercury does not cause a reestablishment of the circuit previously traced due to the contacts 16, 1B of the switch means 14 being concurrently opened. The igniter 63 is also deenergized and remains deenergized for the duration of the running operation which now ensues. stem 46 is moved axially under bias of the coil spring 48 and the closure member 56 no longer closes off the opening 26 in the partition 24.

However, the valve member 26 remains in the open position and the armature 34 in its attracted position relative to the pole faces of the magnet 36 provided the thermocouple 40 is suflioperation and is therefore independent of voltage variations in power supply.

' ment of parts without departing from the scope of The reset ciently heated by the flame at the pilot burner 22.

Such heating of the thermocouple 40 sei'ves to generate current to energize the coil 36 of the magnet 36 as long as the pilot burner flame remains burning. The system is thus set in the steady-state or running operation with the parts as shown in the drawing.

In the event that the flame of the pilot burner 22 is extinguished, then the thermocouple 46 ceases to generate current and the coil 38 becomes deenergized releasing the armature 34 and closing the safety valve l6 by movement of the valve member 28 into engagement with its seat 25. As such movement of the valve member 26 controls only the fiow of fuel to the main burner III. the flow of fuel through the pilot conduit 20 continues. The system is restarted by rotating the handle l8 to the Off position and then back to the On position as illustrated in the drawing. The system is' thus of the non-recycling type and the only fuel which escapes unburned in the event of a safety shut-ofi' is that which flows to the pilot burner. It will be understood, however, that the system could be arranged for 100 per cent shut-off of fuel by connecting the conduit 20 to a chamber provided between the valve member 28 and the closure member 50 as disclosed in Patent No. 2,391,753. It should be observed that the system requires no power for steady-state the invention so that this description and accompanying drawings are intended by way of illustration only and are not to be construed in a limiting sense.

I claim:

1. A control system for fuel burner apparatus having a source of electric energy, comprising electromagnetic control means biased to a fuel flow preventing position; electromagnetic reset means biased to an inoperative position and operable when energized for actuating said control means to a fuel flow permitting position, initially closed switch means adapted for controlling said reset means, a timing device operatively associated with said switch means for delaying operation thereof to an open position until expiration of a predetermined period following energization of said reset means and being substantially instantaneously reset for such operation upon deenergization of said reset means, initially open switch means for controlling said reset means and adapted when closed to establish a circuit including said reset means and said initially closed switch means. thermoelectric means connected to said control means and adapted to be located to be heated suiilciently by burning fuel at the burner during said period for energizing said control means and maintaining the same in said fuel flow permitting position, and means operable for establishing a temporary circuit for said reset means to close said initially open switch means and e tablish the first said circuit.

2. A control system for fuel burner apparatus .having a source of electricenergy, comprising electromagnetic control means biased to a fuel flow preventing position; electromagnetic reset means biased to an inoperative position and operable when energizedfor actuating said control means to a fuel flow permitting position, initially closed switch, means adapted for controlling said reset means, a timing device operatively associated with said switch means for delaying operation thereof to an open position until expiration of a predetermined period following energization of said reset means and 'being substantially instantaneously reset for such operation upon deenergization of said reset means, initially open switch means for controlling said reset means and adapted when closed to establish a circuit including said reset means and said initially closed switch means, thermoelectric means connected to said control means and adapted to be located to be heated sufficiently by burning fuel at the burner during said period for energizing said control means and maintaining the same in said fuel flow permitting position, a second initially open switch means controlling a circuit in parallel with the first said initially open switch means, and means operable for closing said second initially open switch means momentarily to establish said parallel circuit and causing said reset means to close said first initially open switch means and establish the first said circuit.

3. A control system for fuel burner apparatus having a source of electric energy, comprising electromagnetic control means biased to a fuel flow preventing position; electromagnetic reset means biased to an inoperative position and operable when energized for actuating said control means to a fuel flow permitting position, initially closed switch means adapted for controlling said reset means, a timing device operatively associated with said switch means for delaying operation thereof to an open position until expiration of a predetermined period following energization of said reset means and being substantially instantaneously reset for such operation upon deenergization of said reset means, initially open switch means for controlling said reset means and adapted when closed to establish a circuit including said reset means and said initially closed switch means, thermoelectric means connected to said control means and adapted to be located to be heated sufliciently by burning fuel at the burner during said period for energizing said control means and maintaining the same in said fuel flow permitting position, a second initially open switch means controlling a circuit in parallel with the first said initially open switch means, manually operable means for controlling the flow of fuel to said control means, and means operatively associated with said manually operable means for closing said second initial- 1y open switch means momentarily to establish said parallel circuit and causing said reset means to close said first initially open switch means and establish the first said circuit.

4. A control system for fuel burner apparatus having a source of electric energy, comprising electromagnetic control means biased to a fuel flow preventing position, electromagnetic reset means having a coil and plunger operable thereby and biased to an inoperative position, means for mechanically connecting said plunger and said control means for actuation of the latter to a fuel flow permitting position when said coil is energized, initially closed time switch means mechanically connected to said plunger for operation thereby to assume an open position upon expiration of a predetermined period following energizatrol means and maintaining the same in said fuel flow permitting position, and means operable for establishing a temporary circuit for said coil to cause said initially open switch means to close and establish the first said circuit.

5. A control system for fuel burner apparatus having a source of electric energy, comprising a fuel control valve biased to a closed position, electromagnetic means including a coil and an armature connected to said valve and operable for holding the same in open position upon sufficient energization of said coil, a reset stem for actuating said valve to open position and being biased to an inoperative position, electromagnetic means having a winding and a plunger operable thereby between attracted and released positions, means for connecting said plunger to said reset stem for opening said valve upon operation of said plunger to said attracted position, initially closed time switch means operable by said plunger upon operation thereof to said attracted position, said time switch means being adapted to assume an open position upon expiration of a predetermined period following said plunger operation, initially open switch means operable by said plunger to closed position upon operation thereof to said attracted position, said initially open switch means being adapted to establish a circuit in said closed position including said winding and said time switch means, thermoelectric means electrically connected to said coil and located to be heated sufliciently by burning fuel at the burner during said period for energizing said coil and maintaining said valve in open position, a second initially open switch means controlling a circuit in parallel with the first said initially open switch means, manually operable means for controlling the flow of fuel to REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,391,753 Strobel Dec. 25, 1945 2,406,925 Strobel Sept. 3, 1946

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