US2456147A - Burner control system - Google Patents

Description

Dec. 14, 1948. w. A. RAY 2,456,147

BURNER CONTROL SYSTEM Filed Dec. 5, 1944 Confrol 55 Device Thermoslai ML JAM A. DAY.

Patented Dec. 14, 1948 2,456,147 BURNER CONTROL SYSTEM William A. Ray,

eral Controls C0,,

Glendale, Calif., assignor to Gena corporation Application December 5, 1944, Serial No. 566,662

15 Claims.

This invention relates to the control of furnaces, and particularly furnaces utilizing a fluid fuel.

In a prior application flied in the name of William A. Bay on February 28, 1944, under Serial No. 524,212, for Gas heating control system. there is described a system utilizing a pilot burner, a main burner, and valves for both burners, all arranged in a manner similar to that disclosed herein. This applicatlon is a continuation, in part, of the said previously flled application.

In systems 01' this character, it has been proposed to use an igniter for the pilot burner, so that the pilot is used only when the main burner is in operation. The igniter may be in the form of a coil of line wire heated by the passage of an electric current. The introduction into the system of an igniter of this character, in conjunction with a pilot burner active only when it is desired to light the main burner, introduces hazards that must be eliminated. v

For example, it is important that the supply of fuel to the pilotburner be discontinued in the event of failure of the igniter, for otherwise a dangerous accumulation of fuel may occur. Again, it is essential to ensure that the pilot is burning and fully operative before the main valve is permitted to open; and the igniter circuit should be lie-energized as soon as the pilot flame is established. In the event of flame failure, the igniter circuit must not be permitted to be energized for a short period, to allow escape of any unignited fuel. In this way, the danger of an explo: ion is obviated.

It is one of the objects of this invention to provide these safeguards in a simple and effective manner.

It is another object of this invention to make it possible to obtainthe time delay between flame failure and energization of the igniter by a mechanism utilizing no electrical energy, but which, instead, employs a slow release of fluid pressure, as through a constricted passage.

It is another object of this invention to ensure that the pilot flame is fully established before the main valve is open, as by the aid of a delayed action mechanism.

It is another object of this invention to provide a fluid pressure operated switch that is especially adapted to create definite time delays between different phases of operation of the switch.

This invention possesses many other advantages, and has other objects which may be 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:

The single figure is a diagrammatic representation of a system incorporating the invention.

A main burner I is shown, utilizing fluid fuel, such as gas, supplied through a conduit 2. In order to light the burner I, use is made of a pilot burner 3 capable of producing a pilot flame 4 (shown in dotted lines). The pilot burner I is adapted to be ignited by a glow-coil 5, energiz'ed in a manner to be hereinafter described.

The flow of fuel to the main burner l is controlled by an electromagnetically operated valve 6. ,The flow of fuel to the pilot burner 3 is similarly controlled by a pilot burner valvel which may also be electromagnetically operated. The valves 6 and I are each connected independently of each other to the main conduit 2.

The arrangement is such that, when the system requiresit, the burner l is ignited automatically. For this purpose, there is a definite sequence of operations. First of all, the pilot valve 1 is opened; then the igniter 5 is energized; then, in the event the pilot flame 4 is in existence, the main valve 6 is opened. Similarly, when the demand for heat is reduced, all of the circuits are tie-energized, and the system returns to the inactive position shown.

As an example of a means for controlling the energization of the circuit, a thermostat 8 is indicated'. This thermostat may be located in a space or room, the temperature of which is to be controlled. Furthermore, there may be placed in series with the thermostat 8 a control device 9, such as a clock, or the like, that places a. limit upon the period of effectiveness of the thermostat 8.

In order to energize the control circuits, a stepdown transformer I0 is utilized, the primary winding l l of which may be connected to a commercial source of alternating current. The secondary winding I2 produces a relatively low electromotive force, suitable for the control circuits now to be described.

In the event that both of the control devices 8 and 9 are in a condition corresponding to a demand for heat, a circuit is completed for opening the pilot valve 1. This circuit includes the following elements: conductor l3, automatic safety switch '4, conductor II, coil II iii the electroinagnetically operated valve 1, conductor H, a fair of engaged contacts II and II, the conductor 0, a pair of contacts 2|..and ' eonductors 22 and 23, through thecontrol devices I and I, back to the secondary winding l2.

The automatic switch I4 is arranged to open in the event that the igniter I should fail to ignite the pilot burner 2 after a short interval. The manner in which it is controlled will be described hereinafter. It is sumcient, for the present, to note that this automatic switch I4 is located in the conductor I! through which all of the control currents must flow; and, if the switch I4 is open, the entire system is inactive. I

Contacts II and II are normally in engagement while the system is inactive. The contact II is shown as supported on a conducting flexible contact arm 24 that is capable of being moved to open or closed position in a manner to be hereinafter described.

The contacts 2| main closed while are so arranged that they rethe main valve I is closed.

Accordingly, it is seen that, in order to pass fuel to the pilot burner 2, it is necessary that contacts II and ll be in engagement, and that the valve I be closed.

Promptly upon opening of the valve 1, the igniter I is energized. The igniter is shown as energized through a transformer 2I.having a primary winding 28 and a secondary winding 21. The transformer 2I is of the high reactance type that provides a substantially constant current in spite of variations in the impedance of the load. Thus, in the event of inadvertent short-circuiting of the igniter coil I, or any part thereof, no excessive current is permitted to flow.

The circuit for the primary winding 28 is completed as soon as the valve 1 opens through the following elements: conductor I3, safety switch H, a heater element 28, winding 28, contacts 28 and I0, flexible contact arm 8|, conductor 32, stationary contact 22, movable contact '34, and conductor 23 through control devices I and I to the other terminal of the secondary winding l2.

Contacts 29 and II are supported similarly to contacts I! and II.

The contacts 33 and 34 are controlled by the energization of the operating coil II for the valve I. When the operating coil II is energized, corresponding to the opening of valve 1, the contacts It and I4 engage, and the foregoing circuit is completed.

Accordingly, the igniter I lights the burner I, and a flame 4 is inexistence.

The final stage of the cycle involves the opening of the valve 8 and the ignition of burner I. Before proceeding is accomplished, that includes the be described.

The circuit controller that includes these contacts is generally designated by the reference character II. It is arranged to be operated by fluid pressure derived from the main conduit 2. For this purpose it inc1udes,a' movable wall, such as diaphragm II, which is confined at its edges between an upper housing member 31 and a lower housing member 30. The lower member the circuit controlling device contacts I I-IO and 29- will is hollow, defining a gas chamber 3!. This gas chamber is sealed by a flexible wall member 40.

Similarly, the upper casing member 21 is hollow, forming a chamber 4| above the diaphragm II. The chamber 4| is closed by a cover member 42.

with the manner in which this The diaphragm 38 is connected, as by a cievis 42 and link 44. to an arm 4I that is Joined tc the inner side of the flexible wall 40. Arm 4: forms one element of a lever-like arrangement, including a spacer block 48 disposed exteriorly of the wall 40, the finger II, the spacer block 41, and the finger 24. All of these elements 4I, 40, 48, 3|, 4! and 24 are appropriately fastened together. The spacer blocks 48 and 41, as well as the arm 4I, may be appropriately insulated from the current-carrying portions of the apparatus, The spacer block 46 is pivoted for angular movement, as by the aid of the pivot 48, located exteriorly of the wall 40. Such angular movement is permitted by the interposition of the flexible sealing wall 40 between arm 4I and block 46.

When the diaphragm 26 is in its lowered position, as indicated, the lever structure 45-48-41 is in one of its extreme positions, causing contacts II and Ill respectively to engage contacts l9 and 29. However, in the event diaphragm II moves upwardly, the structure is rotated about the pivot 48. This rotation is permitted by the flexibility of the wall 4I Contacts l8 and I! open and contact Iii leaves contact 28 and, in a short while, engages another stationary contact 49.

It is apparent that, when this occurs, the circuit for the coil i I is interrupted at contacts l8- and i9, and the circuit for the igniter I is interrupted by theseparation of contacts 29 and 30. Nevertheless, a holding circuit is completed for the coil II through the stationary contact 50 and movable contact II, which are moved into engagement when coil II is energized. The holding circuit for coil l8 may be traced as follows: conductor II, safety switch l4, conductor II, coil II, contacts I0 and II. and conductor 28 through the control devices 8 and 9 to the secondary winding i2. This holding circuit becomes effective Just as soon as the coil II is energized, and remains eflective until one or the other of the control devices 8 and 8 opens the circuit.

The movement of the diaphragm l6 upwardly causes engagement of the contacts 30 and 49. This completes the circuit for opening the main valve I. This circuit may be traced as follows: conductor II, safety switch l4. conductor 52, operating coil II for valve I, conductor I4, contacts 4i and Ill. contact finger 3|, contacts 33 and 24, conductor 23, through control devices 8 and I to winding l2.

Accordingly, .in order it is essential that the that valve 6 be opened, pilot valve 1 be opened (to cause contacts 33 and 34 to engage) and that the diaphragm 38 be in its upper position, asv indicated in dotted lines in the figure.

Movement ofthis diaphragm 38 upwardly can be accomplished in response to the ignition of the pilot burner 3. When this occurs, thehot Junction of the thermocouple II is'heated by the flame 4 and electrical energy is generated by the thermocouple. This electrical energy serves to energize an eiectromagnet II. This electromagnet is located in the space 4i above diaphragm 36. It serves to attract a pivoted armature I1 against a light spring II. When this occurs, fluid pressure in the space 4| is allowed to be slowly reduced.

The fluid pressures existing above and below the diaphragm 36 in chambers 4i and 3!! respectively are derived from the source of fuel supply. For this purpose, a conduit 58 is provided, connected to the main conduit 2. This conduit has assess? a branch leading into the space ll through a restricted orifice 00. when the electromagnet is unenergized, the fuel pressure is also effective above the diaphragm 30, in the chamber ll, and the weight of the apparatus is sufficient to keep the switch mechanism in the full line position. Fluid pressure is conducted to chamber 4 i through the ports ll, 62,. and 61. The gaseous fuel must pass through a restricted oriflce between ports 62 and t3, and formed between the inner end of the adjustable headless screw N and the adjacent end of port. The port I leads to a Jet nozzle "which is uncovered to admit fuel to the chamber II when the armature I1 is in the de-energized position. Accordingly, in this position the switch mechanism is in the full line position.

As soon' as the armature I1 is attracted by the electromagnet 58, the lower end of the armature closes jet nozzle 65, thus shutting off the source offluid pressure to the chamber ll. At the same time, the let nozzle 68. is opened, and fuel from chamber fl is free to escape through port 01 and conduit 68 to the furnace chamber, indicated by the dotted line 88. In this port opening 61 a restricted orifice Ill is provided in order to cause the escape of gas from chamber H to take place slowly. The diaphragm 35 slowly moves upwardly. Accordingly, the switch mechanism moves slowly between the full line and the dotted line positions.

This slow' movement of the switch mechanism ensures that the pilot flame 4 has been fully established and is no longer in danger of being blown out by the escape of gaseous fuel from burner i, as main valve 8 is opened by closing of contacts 30" and 49. Furthermore, the contact is spaced sufficiently above contact 29 to ensure that the ignition circuit through contacts 28 and it is fully opened before the main valve b can be opened.

In the event of flame failure, the pilot flame Q is extinguished and in a short time the thermocouple structure 56 no longer generates suillcient electricity to keep armature 51 attracted. When this occurs, the armature 51 returns to the inactive position indicated. Gas pressure is then permitted to build up gradually in chamber ll, and ultimately the switch mechanism returns to the full line position. In this position the main valve I is closed, and the process of igniting burner i can begin again if the thermostat 8 and the other control device 9 are in heat demanding position. after the flame fails, there may be an accumulation of unlighted fuel adjacent the burners. If ignited, this would cause an explosion that may result in serious damage. To avoid this,

.a period is required to permit escape of the accumulated gases. It is for this reason that the return of the switch mechanism to the full line' position is retarded by the slow movement of the diaphragm 36 downwardly. This gradual movement is effected, as heretofore stated, by causing the gas to pass into the chamber ll through the restricted oriflce formed between ports 82 and 83 by the screw 64.

As much as several seconds may elapse before the switch mechanism is returned to the position indicated. It is then safe for the pilot burner valve 1 to be re-opened and to begin a recycling of the system.

In the event that the pilot burner 8 fails to light, the heater element 28 eventually functions to cause the safety switch It, which responds to a rise in temperature, to open the circuit. This switch, being in the conductor i3, common to all of the circuits heretofore described, ensures that the entire system is then rendered inactive. Furthermore, the switch I4 is so arranged that it does .not close again when it cools. Accordingly, the

5 system remains inactive while repairs or replacements are made to render the burner 3 operative; and then the switch Il may be manually returned to the closed position. The switch l4 may include .a bimetallic operating element and latch means 10 to hold the switch open until manually released.

Such switches are well known and details are unnecessary to an understandingof the present invention. A detailed description of the switch is shown in Figure 4 of applicant's co-pending case, Serial No. 524,212, flied February 28, 1944.

. The operation of the system is apparent from the foregoing. When the control devices 8 and 9 demand heat, the pilot burner valve 1 is first opened. Then, through contacts 33- and 20-30, the ignition circuit is established. The

burner is then ignited. Shortly after the pilot flame 4, is established, the main valve 8 opens, due to engagement of the contacts 49 and 30, the

- diaphragm 38 having been moved slowly upwardly 5" after the armature 51 is attracted, to open the jet nozzle 38 and to close the Jet nozzle 65.

The inventor claims: 1. In a system of the character described, a fuel burner, fuel supply means for said burner, an

electrically energizable igniter for the burner, a

control circuit for rendering said igniter active including a control device and a fluid pressure operated circuit controller, means for feeding fuel from said supply means to said circuit controller,

said circuit controller comprising means responsive to the existence of a flame at the burner for causing said circuit controller to deenergize the igniter.

' 2. In a system of the character described, a

in fuel burner, fuel supply means for said burner,

an electrically energizable igniter for the burner, fluid pressure operated switch means including a pair of contacts. controlled by the fuel supply pressure, and a control circuit including a control device and said contacts, for rendering said igniter active; said pressure operated switch means including means responsive to the existence of a flame at the burner for causing said :pressure operated switch means to render said wigniter inactive and responsive to the extinguishing of the time for causing said pressure operated switch means to close said contacts, said pressure operated switch means including means for delaying the closing of said contacts upon extinguishing of the flame.

"3. In a system of the character described, a main fuel burner, fuel supply means for said burner, a pilot burner for igniting the main burner, an igniter for said pilot burner, means forming a pair of chambers, one of said chambrs being continuously subjected to the fluid pressure of the fuel therefor, said means controlling passage of fuel to the main burner, and means responsive to the existence of a pilot flame for causing the fuel pressure in the other chamber to operate said control means to pass fuel to the main burner.

4. In a system of the character described, a main fuel burner, fuel supply means for said burner, a pilot burner for igniting the main burner, an igniter for said pilot burner, means forming a pair of chambers, one of said chambers I being continuously subjected to the fluid pressure of the fuel for controlling passage of fuel to the main burner, and means responsive to the existence of a pilot flame'for causin the fuel pressure in the other chamber to operate said control means to pass fuelto the main burner. said means causing operation of the control means including a restricted oriflce fordelaying passage of fuel to the main burner after the pilot flame is established.

5. In a system of the character described. a main fuel burner, fuel supply means for said burner, a pilot burner for igniting the main burner, an electrically energizable igniter for said pilot burner, and means forming a pair of chambers, one of said chambers being continuously subjected to the fluid pressure of the fuel for controlling passage of fuel to the main burner, as well as for rendering the igniter active, and means responsive to the existence of a pilot flame for causing said fuel pressure in the other chamber to operate said control means to pass fuel to the main burner and to render said igniter inactive.

6. In a system of the character described. a main fuel burner, fuel supply means for said burner, a pilot burner for igniting the main burner, an electrically energizable igniter for said pilot burner, and means forming a pair of chambers, one of said chambers being continuously subjected to the fluid pressure of the fuel for controlling passage of fuel to the main burner, as well as for rendering the igniter active, and means responsive to the existence of a pilot flame for causing said fuel pressure in the other chamber to operate said control means to pass fuel to the main burner and to render said igniter inactive, said means causing operation of the control means having provisions for interposing a delay interval between the act of rendering the igniter inactive and the act of causing passage of fuel to the main burner.

7. In a system of the character described. a

fuel burner, fuel supply means for said burner,

an electrically operated igniter for the burner, a circuit controller for the igniter, and means for operating said circuit controller. comprising means forming, a pressure chamber with a movable wall adapted to be subjected to the fluid pressure of the fuel on both sides, and means responsive to the existence of a flame at the burner to release the fluid pressure from one side of said wall for causing the fluid pressure of the fuel on the opposite side to move the wall and thereby de-energize the igniter.

8. In a system of the character described, a fuel burner, fuel supply means for said burner, an electrically operated igniter for the burner, a circuit controller for the igniter, and means for operating said circuit controller, comprising means forming a pressure chamber with a movable wall on an side of which thafluid pressure of the fuel is continuously effective and means responsive to the failure of the flame at the burner to cause the fluid pressure of the fuel to act on the opposite side of said wall to urge the wall.to a position to cause energization of the igniter.

9. In a system of the character described, a fuel burner, fuel supply means for said burner an electrically operated igniter for the burner, a circuit controller for the igniter, and means for operating said circuit controller, comprising means forming a pressure chamber with a movable wall, and means responsive to the existence of a flame at the burner for causing the fluid pressure of the fuel to move the wall in one direction and thereby de-energize the igniter, said means being responsive to the failure of the flame for causing said fluid pressure to urge said wall to move in another direction for returning the circuit controller to energizing position, the said flame responsive means also having means for delaying movement of the wall in at least one of said directions.

10. In a system of the character described. a main fuel burner, fuel supply means for said burner. a pilot burner, an electrically operated valve for the main fuel burner, an electrically operated igniter for the pilot burner, a circuit controller having alternate positions energizing either the igniter or the valve, means forming a -to operate the circuit energizing position to pressure chamber with a movable wall, said wall being mechanically connected to'the circuit controller whereby movement of the wall in opposite directions causes corresponding movement of the circuit controller, and means responsive to the existence of a flame at the pilot burner for causing the fluid pressure of the fuel to move the wall to operate the circuit controller from an igniter energizing position to a valve energizing position.

11. In a system of the character described, a main fuel burner. fuel supply means for said burner, a pilot burner, an electrically operated valve for the main fuel burner, an electrically op. erated igniter for the pilot burner, a circuit controller having alternate positions energizing either the igniter or the valve, means forming a pressure chamber with a movable well, said wall being mechanically connected to the circuit controller whereby movement of the wall in opposite directions causes corresponding movement of the circuit controller, means responsive to the existence of a flame at the pilot burner for causing the fluid pressure of the fuel to: move the wall controller from an igniter a valve energizing position: and means delaying the movement of the wall.-

12. In a system of the character described, a main fuel burner, fuel supply means for said burner, a pilot burner, an electrically operated valve for the main fuel burner, an electrically operated igniter for the pilot burner. a circuit controller having alternate positions energizing either the igniter or the valve. means forming a pressure chamber with a movable wall, said wall being mechanically connected to the circuit controller whereby movement of the wall in opposite directions causes corresponding movement of the circuit controller, and means responsive to the existence of a flame at the ilot burner for causing the fluid pressure of the uel to move the wall to operate the circuit controller from an igniter energizing position to a valve energizing position, as well as responsivetp failure of the pilot flame for causing the fluid pressure of the fuel to move the wall to lie-energize the valve and energize the igniter.

13. In a system of the character described. a'

main fuel burner, fuel supply means for said burner, a pilot burner, an electrically operated valve for the main fuel burner. an electrically operated igniter for the pilot burner, a circuit.

directions causes corresponding movement of the' circuit controller, means responsive to the existence of a flame at the pilot burner for causing the fluid pressure of the fuel to move the wall to operate the circuit controller from an igniter energizing' position to a valve energizing position, as

well as responsive to failure of the pilot flame for causing the fluid pressure of the fuel to move the wall to de-energize the valve and energize the igniter, and means delaying the movement of the wall to the igniter energizing position.

14. In a system of the character described, a main fuel burner, fuel supply means for said burner, a pilot' burner, an electrically operated valve for the main fuel burner, an electrically operated igniter for the pilot burner, a circuit controller having alternate positions energizing either the igniter or the valve, means forming a pressure chamber with a movable wall, said wall being mechanically connected to the circuit controller whereby movement of the wall in opposite directions causes corresponding movement of the circuit controller, and means responsive to the existence of a flame at the pilot burner for causing the fluid pressure of the fuel to move the wall to operate the circuit controller from an igniter energizing position to a valve energizing position, as well as responsive to failure of the pilot flame for causing the fluid pressure of the fuel to move the wall to de-energize the valve and energize the igniter, the circuit controller being so arranged that a substantial movement of the circuit controller is required after the igniter is de-energized, before the valve is energized.

15. In a system of the character described. a

main fuel burner, fuel supply means for said a burner, a pilot burner, an electrically operated valve for the main fuel burner, an electrically operated igniter for the pilot burner, a circuit controller having alternate positions energizing either the igniter or the valve, means forming a a pressure chamber with a movable well, said wall being mechanically connected to the circuit controller whereby movement of the wall in opposite directions causes corresponding movement of the circuit controller, means responsive to the existence of a flame at the pilot burner for causing the'fluid pressure of the fuel to move the wall to operate the circuit controller from an igniter energizing position to a valve energizing position, as well as responsive to failure of the pilot flame for causing the fluid pressure of the fuel to move the wall to de-energize the valve and energize the igniter, the circuit controller being so arranged that a substantial movement of the circuit controller is required after the igniter is deenergized, before the valve is energized, and means for delaying the motion of the wall.

WILLIAM A. RAY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS English Dec. 15, 1942

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