US2479779A

US2479779A - Thermostatic safety control system for gas burners

Info

Publication number: US2479779A
Application number: US524212A
Authority: US
Inventors: William A Ray
Original assignee: General Controls Co
Current assignee: General Controls Co
Priority date: 1944-02-28
Filing date: 1944-02-28
Publication date: 1949-08-23
Anticipated expiration: 1966-08-23

Description

Aug. 23, 1949. w. A. RAY 2,479,779

THEBMOSTATIQ SAFETY CONTROL SYSTEM FOR GAS BURNERS Filed Feb. 28, 1944 3 Sheets-Sheet l I I l l .J 5 25 Y j Aufomaf/cfiw/fc/ubg e 43 I aka ice \N v ENTOR l Vfl/iam A. Ray BY ATTORN EY Aug. 23, 1949. w, RAY 2,479,779

THERMOSTATIC SAFETY CONTROL SYSTEM FOR GAS BURNERS Filed Feb. 28, 1944 3 Sheets-Sheet 2 BY W K ATTORNEY A118. 1949- w. A. RAY 2,479,779

THERMQSTATIC SAFETY CONTROL SYSTEM FOR GAS BURNERS Filed Feb. 28, 1944 3 Sheets-Sheet 3 Aufomafk SW/k/I/hg 04 u lil 7 Der/cc 22 n nuuum INVENTOR l Vi/a APay BY ATTOR N EY Patented Aug. 23, 1949 UNITED STATES PATENT ori ice THERMOSTATIC SAFETY CONTROL SYSTEM FOR GAS BURNEBS William A. Ray, Glendale, CaiiL, assignor to General Controls 00., a corporation Application February 28, 1944, Serial No. 524,212

stat. The valve is usually operated byan-elegtromagnet, the circuit of which is energized'and de-energized in accordance with the position of the thermostat.

In such systems, in the event the pilot flame is extinguished for any reason, provisions are made to ensure that the main valve to the burner remains closed until the pilot flame is re-estab-' lished. Until that time, the heating system is shut down.

It is one of the objects of this invention to provide a heating system that obviates these disadvantages and that, nevertheless, ensures operation with safety, and with assurance against premature ignition of the main-burner.

It is another object of this invention to cause automatic operation of the pilot burner in response to the operation of the controlling thermostat, and to ensure that the pilot burner can be lighted only upon the ex stence of safe conditions. In this way, the pilot burner is lighted only when the main burner is to be lighted.

It is another object of this invention to ensure that, before the pilot burner can be lighted, the danger of an explosion in the furnace chamber is eliminated. This is accomplished by ensuring that the supply of fuel to the pilot burner can occur only when certain conditions are fulfilled, such as that the supply of fuel to the main burner be substantially interrupted; that there be no failure in the control circuit, such as open circuits or short-circuits; that the igniter for the pilot burner is operative; and that a period of time sufficient to clear the furnace of an explosive mixture must elapse between successive attempts to ignite the pilot burner.

It is still another object of this invention to ensure that the main burner can be supplied with fuel only after the pilot burner valve is opened and the pilot burner is in operation.

It is still another object of this invention to ensure that, in the event of flame failure, the supply of fuel to the main burner is interrupted; and that the automatic re-ignition of the system can occur only after a definite period has elapsed to permit .the furnace chamber to be cleared of an explosive mixture.

It is still another object of this invention to interrupt all flow of fuel in the event the pilot burner should fail to ignite after a definite time interval.

It is still another object of this invention to provide a fuel control mechanism, such as a 13 Claims. (Cl. 158-1171) valve, in which circuit controlling devices are incorporated, whereby the mechanism serves not only to control the flow of fuel. but also as a relay. f

It is still another obiect of this invention to provide a valve structure especially adapted to be used for controlling the supply of gaseous ,fuelto the main burner, and arranged so that it can substantially entirely cut off the supply 'offuel; although the closure may be prevented by dirt, or the "like, from closing entirely.

"It is still another object of this invention to provide an electric circuit controlling device that functions effectively for the dual purpose of timing successive operations of the igniting system and of interrupting the flow of fuel in the event there is a failure to ignite the pilot burner.

This invention possesses many other advantages, and has other objects which may be made more clearly apparent from a consideration of several embodiments of the invention. For this purpose there are shown a few forms in the drawings accompanying and forming part of the present specification. These forms 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 the invention is best defined by the appended claims.

Referring to the drawings:

Figure 1 is a diagrammatic representation of a gas heating installation embodying the invention;

Fig. 2 is a sectional view of a valve for controlling the flow of fuel to the main burner of the system;

Fig. 3 is a sectional view of a valve for controlling the flow of fuel to the pilot burner that is used to ignite the main burner;

Fig. 4 is a diagrammatic view of a combination timer and safety switch mechanism utilized in the invention;

Fig. 5 is a wiring diagram of the system illustrated in Fig. 1, the system being inactive, and the main burner being extinguished;

Fig. 6 is a diagram similar to Fig. 5, but illustrating an intermediate stage of operation of the system;

Fig. '7 is a diagram similar to Fig. 5, showing the fully operative stage of the system; and

Fig. 8 is a view similar to Fig. 5, of a modified form of the invention.

In Fig. 1 there is shown a main burner i adapted to be supplied with fuel through the pipe or conduit 2. The flow of fuel to the main burner is controlled by an electromagnetically operated valve 3, interposedin the conduit 2. This valve 3 is shown in greater detail in Fig. 2.

The inlet side of the valve is connected to a pipe 4 that leads to an appropriate source of aseous fuel.

For igniting the main burner I, use is made of a pilot burner}. This pilot burner 5 is shown as supplied with fuel through a conduit 3, also connected in an appropriate manner to the source of gaseous fuel. In the conduit 6 is interposed a pilot burner valve I. This valve I is shown in greater detail in Fig. 3.

The heating system may be in the form of a furnace-adapted to heat a space, such as a room or building. The main burner I is electrically controlled by aid of valve 3 so that it remains inactive until there is demand for additional heat. In this inactive stage the pilot burner 5 is also extinguished.

When conditions demand the lighting of the main burner I, the controls operate in sequence to open the pilot burner valve I and to ignite the pilot burner by the aid of an igniter 3; and, as soon'as the pilot burner 5 is in full operation,

the main valve 3 is permitted to open, and the main burner I is ignited.

As soon as conditions demand that the main burner I be extinguished, the main valve 3 is closed and the pilot burner valve 1 is also closed. The system then is in its inactive condition.

The safeguards and protective devices incorporated in the system may be more readily explained in connection with Figs. 5, 6, and 7.

One of the important safety devices is an apparatus that responds to the heat of the pilot flame, and that is arranged to maintain the system inoperative unless the pilot flame is in existence. Such a safety device may, for example, include a thermostat adapted to be influenced by the heat of the pilot flame. In the present instance, however, use is made of a thermoelectric device, or thermocouple 9, indicated diagrammatically in Figs. 1, 5, 6, 7, and 8. The thermocouple is shown in Fig. 1 as being disposed close to the pilot burner 5 so as to be heated by the pilot flame.

The electrical energy generated by the thermocouple 9 is used to operate a safety relay Ill (Figs. 5 to 8 inclusive). The safety relay III is operated by the coil II of an electromagnet. While the pilot burner 5 is inactive, the coil II is de-energized and the armature I2 of the relay III is in the lowered or dropped position illustrated in Figs. 5, 6, and 8. When the pilot burner 5 is energized, the armature I2 moves to the attracted position of Fig. 7 by the electromagnet coil I I.

When this occurs, the main valve 3 is opened and the main burner I is rendered active. For operating the main valve, use is made of electromagnet M (see, also, Fig. 2) that, when energized, causes the valve 3 to open.

In the inactive or off position of Fig. 1, both mainvalve 3 and the pilot burner valve I are closed. The initiation of the operation of the system is dependent upon the operation of the switching device I3, which may be automatic, as a room thermostat.

In Fig. 5 the control circuits are shown as supplied with electric energy through a stepdown transformer I4. While the switching device I3 is in open position, as illustrated in this figure, the control circuits are inactive. The relay' III is de-energized and armature I2 is in a position such as to render the back contact I5 active.

When the switching device I3 is closed, as illustrated in Fig. 6, the control circuit is energized through the back contact I5 to cause the pilot valve 1 to open. This is caused by energization energizing circuit is dependent upon certain safety factors that must exist: Thus, the circuit for the coil P may be traced as follows: lead It from transformer I4, switching device I3, lead II, a'safety switch S1, lead I8, armature I2, back contact I5, 9. safety heating device I9, the igniter 8, switch M1, switch T1 or P: which are in parallel, a section of coil P, to the transformer I4 by the other lead 25.

In order for this circuit to be energized, therefore, it is necessary that each and every one of the elements in series be capable of transmitting electrical energy; that is, the switch S1 must be. closed; the back contact I5 must be engaged by armature I2; the safety heater I9 must be in operative condition; the igniter 8 must be good; the switch M1 must be closed; and either switch T1, or switch Pa, or both, must be closed.

The switch M1 is closed only when the main valve 3 is in substantially closed position, such as illustrated in Fig. 2. The manner in which this is effected will be described in connection with the description of the main valve 3.

The switch T1 is operated to open and closed position by the fiexure of a bi-metallic bar 2I (Fig. 4). This switch closes only after a sufficient interval has elapsed to purge all unignited fuel from the furnace chamber; and the danger of an explosion is thus avoided. Its specific mode of operation will be described hereinafter.

The heater I9 is shown as a coil in Fig. 4 that is in heat transfer relation to the bimetallic bar 2I. Upon an undue delay in the ignition of the pilot burner 5, this heating coil I9 causes the bar 2| to flex so far as to cause the safety switch S1 to open.

However, assuming that the igniter 8 is goou, and that the switches Ml and T1 are closed, the pilot burner valve I is opened by the energization of a section of the coil P.

Accordingly, the igniter 8 can then light the burner 5, and the pilot flame thereupon heats the thermoelectric device 9.

When the thermocouple 9 generates suflicient electrical energy to energize relay coil II, the armature I2 is attracted to the position illustrated in Fig. 7. Accordingly, the front contact 22 is now engaged by the armature I2, and another control circuit, paralleling the first one described, is rendered active. This control circuit likewise energizes the pilot burner electromagnetic coil P. The movement of the armature I2 from the unattracted position of Figs. 5 and 6 to the attracted position of Fig. 7 is so rapid that the pilot burner valve I does not close before the second control circuit is energized.

The second control circuit may be traced from transformer I4 through lead I6, switching device I3, lead I'I, safety switch S1, lead I8, armature I2, front contact 22, a timer heater 23 in parallel with a timer switch T2, a switch P1, coll P, and to transformer I4 through lead 25. Accordingly, in order for this circuit to-remain energized, it is necessary that the relay armature I2 be in attracted position; that is, that the pilot burner flame must be on." Furthermore, the switch P1 must be closed. This switch P1 is arranged to be closed only when the pilot burner valve 1 is open; in other words, if, for any reason, the pilot burner valve I should close, the switch P1 would open and the control circuit just traced would be open-circuited. The timer heater 23 is shown in Fig. 4 as also in heat transfer relation with the bl-metallic bar 2|.

The energization of relay coil II also causes energization of the electromagnet M for main valve 3. This occurs by the aid of the additional front contact 24. The circuit for the coil M is then completed through lead It and switching device I3, lead l1, safety switch S1, lead [8, armature l2, front contact 24, coil M, and a switch P2. The switch P2, as shown in Fig. 3, is also arranged to be closed only in the event that the pilot burner valve 1 is open. Accordingly, the control circuit for the main valve 3 cannot be operated unless the safety switch S1 is closed, the thermocouple 9 is active, and the pilot burner valve is open, maintaining switch P2 closed. This running condition is shown in Fig. 7, the main burner then being lighted.

The main valve 3 is shown diagrammatically in Fig. 2. The valve includes a body 26. This body has a partition 21 separating the inlet 28 from the outlet 29. The partition 21 has a tubular port 30. The upper edge 3| of the port is formed as a narrow valve seat upon which the valve closure member 32 may rest.

The valve closure member 32 is in the form of a disc and is attached to a flexible diaphragm 33 that is disposed over the upper flange of the body 26. A stiffening washer 34 is disposed on the upper side of the diaphragm 33.

The closure member 32, the diaphragm 33. and the washer 34 are held together by the aid of a bolt 35. Furthermore, there is provided a supplemental closure 36 that is intended to telescope within the port 30. This closure 36 may be in the form of an inverted cup extending considerably below the main closure 32.

In the event the main closure 32 fails to seat accurately, the supplemental closure 36 nevertheless serves substantially entirely to interrupt the flow of fuel through the valve 3.

Operation of the valve is effected by the aid of fluid pressure. For this purpose, a chamber 31 is provided above the diaphragm 33, as by the housing 38. This housing 38 is supplemented by a sheet metal cover 33 sealed to the top of the housing 38 and serving to provide a, sealed space above the diaphragm 33.

The diaphragm 33 may be urged downwardly to closed position by the flu d pressure existing in the intake side of the'valve 26. This is accomplished by the aid of the passages 43 and 4!, formed respectively in the body 26 and the housing 38. The outlet of passage M is connected to a jet member 42. Through the jet member, the fluid fuel passes into the chamber 31.

Should it be desired to open the valve, the jet member 42 is covered, and the chamber 31 is vented. This is accomplished by movement of an electromagnetic armature 43, shown as pivoted at 44. It is normally urged in a counterclockwise direction, as by a spring 45, so that its lower end uncovers the jet 42. However, when the electromagnet M is energized, as heretofore described, the armature 43 is attracted against the force of the spring 45. In the attracted po sition, the armature covers the jet 42 and uncovers another jet 46 that is connected through a conduit 41 to the external atmosphere. In this way, the chamber 31 is vented and the inlet pressure on the lower side of the diaphragm 33 is sufficient to cause the valve to open.

The conduit 41, as shown most clearly in Fig:

1, may be led to the main burner I so as to cause 6 the fuel vented from chamber 31 to be harmlessly consumed.

As heretofore stated, opening of the valve 3 causes opening of the switch M1. This open position is illustrated in the running condition of Fig. 7, and ensures that only when the valve 3 is closed is it possible to open the pilot burner valve 1 and to energize the igniter 8.

The switch M1 is illustrated at the upper portion of Fig. 2. It includes the spring arms 81 and 88, insulated from each other and carrying the co-operating contacts 48 and 49. Normally, these spring arms are separated, so that the contacts 48 and 49 are open. However, when the valve 3 is closed, the contacts 48 and 49 are urged together by a spring arm 50 that is disposed above the spring arm 81. This spring arm 50 carries the abutment 5| engaging the upper arm 81. It is urged downwardly by the aid of a stem or rod 52 that is joined to the arm 50. The lower end of the stem 52 is connected to an intermediate point of a lever 54 pivoted on a bracket 55 in the housing 38. The extremity of the lever 54 is forked and is in sliding engagement with the reduced portion 56 of the bolt 35. The chamber 31 is maintained fluid tight in spite of the passage of the stem 52 out of the cover 39, as by the aid of the flexible .bellows member 53. The switch M1 is enclosed in a cap 51.

Closing of the valve 3 by the exertion of fluid pressure above the diaphragm 33 thus serves, as well, to apply a force to the lever 54 which, in turn, pulls the stem 52 downwardly to close the switch M1.

The pilot burner valve 1 is shown in greater detail in Fig. 3. In this instance, the valve body 58 is shown as having a ported partition SQ-that separates the inlet side 60 from the outlet side iii. The electromagnet, including thecoil P, is supported in a housing 62 attached to a collar 63. This collar 63 is threaded in fluid tight relation into the top of the body 53.

The electromagnetic coil P operates upon a solenoid core 64 which is joined to the conical closure member 65. A light spring 66 exerts a force urging the closure member downwardly against its seat. When the coil P is energized, the force of this spring is overcome, and the valve opens.

The switches P1, P2, and P3, which are operated in accordance with the operation of valve 1, are arranged below the body 58 and are shown as enclosed in a casing 61. This casing 61 is supported on the threaded shank 68 that is accommodated in the lower portion of the valve body 58. The lower contacts 69, 10, and 10-a of the switches P1, P2, and P2, respectively, are carried on a support 11. This support is mounted on the bottom of a movable stem 12 which is guided in the shank 68. The upper end of the stem cooperates with the lower surface of closure 65. When the closure 65 is in place on its seat, it urges the stem 12 downwardly against the pressure of the spring 13 to open the switches P1, P2, and P3.

The co-operating upper contacts 14, 15, and 15-a of the switches P1, P2, and P3 are supported upon a plate 16. This plate 15 is resiliently supported upon a plurality of spring mounts 11. The co-operating contacts of the switches P1, P2. and P: can thus readily accommodate themselves to provide effective contacting areas.

While the electromagnetic coil P is deenergized, the switches P1, P2, and P3 are in the posi- T1 with respect to the actuator 18.

tion shown. When the core 64 is lifted to open the valve, the spring I3 causes the stem 12 to rise and to bring contacts 69, I0, and |a against the contacts 14, T5, and '|5a respectively.

The coil P is shown as having two sections.

Only one section is energized when the first control circuit is active, as shown in Fig. 6. When the armature I2 is raised to the active position of Fig. '7, the control circuit for the valve I is such that all of the turns of coil P arp active. The difference in the number of turns that are active in the two control circuits is provided in order to equalize the electromagnetic force exerted by the coil P when either control circuit is active.

The timer device diagrammatically illustrated in Fig. 4 is provided to open the safety switch S1 in the event that the pilot burnerfails to ignite after an interval. It also serves to operate the contacts forming switch T1 which ensures against completion of the igniter circuit until a definite time has elapsed after burner is extinguished, thereby preventing explosions of unconsumed fuel in the chamber.

This combination switch includesthe bi-metal- 25 lic bar 2| heated by the safety heater l9, as well as by the timer heater 23. The bar 2| carries an actuator 18 at its free end. This actuator 18 has two operating portions 19 and go.- The operating portion 19 serves to operate the switch T2 formed by the flexible or spring arms 8| and 82. The switch T2 is used alternately to shortcircuit the-heater 23 and to cause operation of the heater 23 for the purpose of keeping the bimetallic bar 2| in a normally heated condition 5 while the main burner is on.

For this purpose, the lowerarm 82, when bar 2| is cold, rests upon the portion 19. The switch T2 is then open. Accordingly, when the circuit is otherwise completed, the timer heater 23 is active; and, after an interval, the bar 2| flexes Sufiiciently to close the switch T2, immediately short-circuiting the heater 23. After a time, the bar 2| cools off and flexes downwardly, opening the switch T2. This then re-energizes the heater 23 and the cycle is repeated. In this manner, the bi-metallic bar 2| is kept at an average flexure, between the limits required to open and close the switch T2.

The flexure of the bar 2 l, corresponding to this normal operation, is suflicient to keep the switch T1 continuously open. This is accomplished by proper choice of spacing of the contacts of switch Switch T1 is shown as formed by the

flexible arms

83 and 84, upon which the switch contacts are mounted.

Accordingly, should there be a flame failure, the switch T1 will not close until the bar 2| cools. The period of cooling is so fixed as to ensure that any accumulated gases in the furnace chamber will have been dissipated.

After the automatic switching device i3 is closed and the first control circuit, including the igniter 8, is completed through the safety switch S1, as illustrated in Fig. 6, the proper operation of the system requires that the pilot burner 5 be lighted. This stage must occur while the circuit is in the condition of Fig. 6. In the event the pilot burner fails to ignite after a suihcient period, the safety switch S1 is caused to open, and this switch stays open until it is manually closed.

For this purpose, the switch S1 as shown in Fig. 4 is held in closed position by the member 18, the flexible arm 85 of the safety switch S1 being thereby held in a flexed position. It is only upon extended flexing of the bar 2|, due to continued heating by the heater |9,.that the member 18 moves upwardly out of the path of the 5 arm 85. Under such circumstances, arm 85 is free to move to the left, and switch s1 opens. The entire system is thus rendered inoperative. Furthermore, since the top of the spring arm 85 then projects underneath the member I8, the

switch S1 cannot again close until the arm 85 is til conditions are normal.

A complete rsum oi the operation of the system may now be set forth. The normal -inactive position is shown in Fig. 5. In this position, the automatic switching device |3 is inac- I ,tive.

The timer having cooled off, the timer switch T1 is closed. Since the switch l3 serves to disconnect the transformer I4 from all of the control circuits, the electromagnetically operated main valve 3 is closed; and, accordingly, the switch M1 is likewise closed. Similarly, since the pilot burner valve I is likewise inactive, the switches P1, P11, and P3 are open; and, lastly, the armature l2 of relay I0 is in the lower or dropped position.

Furthermore, it is assumed that the safety switch S1 has been placed in the closed position. Now, in the event the switch device l3 closes, the first step after it is closed is illustrated in the intermediate position of Fig. 6. The first control circuit, including the igniter 8 and a section of the coil P, is energized through the closed switches T1 and M1. As soon as this energization takes place. the switch Pa acts to short-circuit the switch T1. This short-circuiting is essential,

40 for the switch T1 will soon open under the influence of the heating produced by the safety heating coil l9. Thus, the control circuit would open even before the thermocouple 9 could generate sufliclent electric energy to energize relay coil causing the armature 2 to move to its upper position and energize coil P through the circuit which includes contact 22.

The control circuit. corresponding to the lower or unenergized position of armature l2. remains active until the pilot burner 5 is lighted and the thermocouple 9 is active to energize coil N. If this takes an unduly long time, the safety switch S1 opens by virtue of the extreme flexure of the bi-metallic bar 2| under the influence of safety heater 1 9.

Assuming, however, that the pilot burner 5 is ignited and that the thermocouple 9 is active, the running stage of operation is reached and is indicated by Fig. "I. In this stage, the armature I2 is attracted to its upper position, causing de-energization of the igniter 8. The closing of the

front contacts

22 and 24, respectively, maintains the pilot burner valve -'I open, thus holding switches P1, P1. and P3 closed, and causes 65. the main valve 3 to open, thus opening switch Fig. 5.

In the event of flame failure, the armature f2 would drop from the active position of Fig. 7, due to the cooling of thermocouple 9. This de-energizes coil M, allowing main valve 3 to close. as well 7.5 as de-energizlng coil P by breaking the circuit ineluding contact 22. The pilot burner valve I closes more rapidly than the main valve 3 due to the diaphragm 33 in the latter; hence switch P3 is open before M1 closes. Accordingly, neither energization of the igniter 8, nor opening of the pilot burner valve I, can occur until bar 2! cools suiflciently to close switch T1, as shown in Fig. 5. This period is chosen to be suflicient to ensure that the furnace chamber is freed of any explosive unconsumed fuel mixture.

Thus, reviewing, upon flame failure, although the back contact I5 would be made quite rapidly, and switch T1 would be temporarily by-passed by switch P3, switch M1 would still be open because main valve 3 was not closed. But, if main valve 3 was not open, switch M1 accordingly being closed, it would be satisfactory to energize the igniter 8, since, under these conditions, there would be no destructive volume of gas in the furnace.

The system is safeguarded in numerous ways. Any accidental mechanical failure, such as a break in any of the leads, or in any of the electrical elements, would cause the system to return to the inactive position of Fig. 5. Between the period of activity, the pilot burner valve must be closed, and the igniter 8 is inactive. It is only upon the energization of the system by closing of the switch l3 that it is possible to start the sequence of operations heretofore described. This sequence must occur in a definite pattern; and, if it does not, the system again must return to the inactive position of Fig. 5.

In the form of the invention illustrated in Figs. 5, 6, and 7, the main valve electromagnet M is shown as controlled by a separate front contact 24. However, it is possible to place the main electromagnetic coil M directly in parallel with the relay coil ii. Such a modification is illustrated in Fig. 8. The circuit for the coil M then includes thermocouple 9, as well as the switch P2 that is closed only when the pilot burner valve 1 is open. Thus,in this case, the main valve is directly under the control of thermocouple 9. This provides an added safety factor.

The inventor claims:

1. In a gas heating system including a pilot burner: an electrically operated valve for'controlling the flow of fuel tothe pilot burner; a pair of control circuit means for independently operating said valve; means responsive to the existence or non-existence, of a flame at the pilot burner for rendering one or the other of the circuit means capable of functioning; that one of said circuit means, which is capable of functioning when there is no flame issuing from the pilot burner, including an igniter in series in the circult; and the other of said circuit means, which is capable of functioning when a flame is issuing from the pilot burner, including a switch in series in the circuit; and means closing said switch only when the pilot burner valve is open.

2. In a gas heating system including a pilot burner: an electrically operated valve for controlling the flow of fuel to the pilot burner; a pair of control circuit means for independently operating said valve; and means responsive to the existence or non-existence of a flame at the pilot burner for rendering one or the other of the circuit means capable of functioning; that one of said circuit means, which is capable of functioning when there is no flame issuing from the pilot burner, including an igniter in series in the circuit, as well as a timer switch; and the other of said circuit means, which is capable of 1o functioning when a flame is issuing from the pilot burner, including a timing device in series in the circuit for operating said timer switch for causing it to open; said timer switch being so constructed as to remain open for a time after the pilot burner flame is extinguished.

3. In a gas heating system including a main burner and a pilot burner: an electrically operated valve for controlling the flow of fuel to the pilot burner; a pair of control circuit means for independently operating said valve; means responsive to the existence or non-existence of a flame at the pilot burner for rendering one or the other of the circuit means capable of functioning; that one of said circuit means, which is capable of functioning when there is no flame issuing from the pilot burner, including an igniter in series in the circuit, as well as a switch that'is closed only while there is an insubstantial supply of fuel to the main burner; means. for supplying fuel to the main burner; and circuit means for causing fuel to be supplied to the main burner by said fuel supply means, and capable of functioning only while a flame is issuing from the pilot burner.

4. In a gas heating system including a main burner and a pilot burner: an electrically operated valve for controlling the flow of fuel to the pilot burner; a pair of control circuit means for independently operating said valve; means responsive to the existence or non-existence of a flame at the pilot burner for rendering one or the other of the circuit means capable of functioning; that one of said circuit means which is capable of functioning when there is no flame issuing from the pilot burner, including an igniter in series in the circuit means, as well as a safety switch, and a heater for the safety switch that eventually causes the safety switch to open in the event the pilot burner flame fails to be ignited, the failure to ignite thus causing the means responsive to pilot burner operation to maintain said one of said circuit means in a condition capable of functioning; the other of said control circuit means including a series switch that is closed in response to the opening of the pilot burner valve.

5. In a gas heating system including a main burner and a pilot burner: relay means including a movable member; means responsive to the heat of the flame issuing from the pilot burner for controlling said relay means, said relay means havin front and back contacts adapted to be engaged, respectively, by said member in accordance with the existence and the non-existence of a pilot flame; an electrically operated valve for supplying fuel to the pilot burner; a first control circuit means which, when energized, causes said valve to open, said first control circuit means being in series with the back contact and including in series an igniter for the pilot burner as well as means for operating said pilot burner valve; a second control circuit means which, when energized, causes said valve to be maintained in open position, said second control circuit means being in series with the front contact; and electrically operated valve means for supplying fuel to'the main burner and operative in response to the energization of said relay means.

6. In a gas heating system including a main burner and a pilot burner; relay means including a movable member; means responsive to the heat of the flame issuing from the pilot burner for controlling said relay means, said relay means 1 having front and back contacts adapted to be engaged, respectively, by said member in accordance with the existence and the non-existence of a pilot fiame; an electrically operated valve for supplying fuel to the pilot burner; a first control circuit 'means which, when energized, causes said valve to open, said first control circuit means being in series with the back contact and including in series an igniter for the pilot burner as well as means for operating said pilot burner valve; a second control circuit means which, when energized, causes said valve to be maintained in open position, said second control circuit means being in series with the front contact; electrically operated valve means for supplying fuel to the main burner and operative in response to energization of said relay means; and a safety switch in series with that control circuit means of which the contact is engaged by said member, as well as with the electrically operated valve means for supplying fuel to the main burner; said first control circuit means including in series, a safety switch heater that causes said safety switch to open in the event said first control circuit means remains energized for a period of time.

"I. In a gas heating system including a main burner and a pilot burner: relay means including a movable member; means responsive to the heat of the fiame issuing from the pilot burner for controlling said relay means, said relay means havin front and back contacts adapted to be engaged, respectively, by said member in accordance with the existence and the non-existence of a pilot flame; an electrically operated valve for supplying fuel to the pilot burner; a first control circuit means which, when energized, causes said valve to open, said first control circuit means being in series with the back contact and including in series an igniter for the pilot burner as well as means for operating said pilot burner valve; a second control circuit means which, when energized, causes said valve to be maintained in open position, said second control circuit means being in series with the front contact; said first control circuit also including in series a timer switch; said second circuit means including in series a heater that causes the timer switch to open, and that permits the timer switch to be closed only upon cooling sufiiciently.

8. In a gas heating system including a main burner and a pilot burner: relay means including a movable member; means responsive tothe heat of the flame issuing from the pilot burner for controlling said relay means, said relay means having frontand back contacts adapted to-be engaged, respectively by said member in accordance with the existence and the non-existence of a pilot flame; an electrically operated valve for supplying fuel to the pilot burner; a first control circuit means which, when energized, causes said valve to open, said first control circuit means being in series with the back contact and including in series an igniter for the pilot burner as well as means for operating said pilot burner valve; a second control circuit means which, when energized, causes said valve to be maintained in open position, said second control circuit means being in series with the front contact; electrically operated valve means for supplying fuel to the main burner; a third control circuit means adapted to be energized in response to the energization of said relay means. and which, when energized, operates the main valve; said first control circuit means including in series a timer switch, a switch closed during unsubstantial supply of fuel to the main burner, and means forming a relay, having a coil in series in the said first control circuit means for short-circuiting said timer switch, said second control circuit means including in series, a switch closed when the pilot burner valve is open, and a heater for the timer switch that, when heated, causes the timer switch to open and to remain open; said electrically operated valve means for supplying fuel to the main burner including an energizing circuit in which there is a series switch operated to close position when the pilot burner valve is open; and a safety switch in series with those control circuit means in condition to be energized; said first control circuit means including a heater for the safety switch that causes the safety switch to open after the first control circuit means is energized for an interval. 9. In a gas heating system including a main burner and a pilot burner; a relay'having an operating coil, front and back contacts and a member movable in response to energization and de-energization of said' coil and adapted to engage respectively said contacts; means responsive to the heat of the fiame issuing from the pilot burner for energizin said coil; said front and back contacts being engaged respectively by said member in accordance with the existence and the non-existence of a pilot flame; an electrically operated valve for supplying fuel to the pilot burner; a first control circuit means which, when energized, causes said valve to open, said back contact being in series with said first control circuit and including in series an igniter for the pilot burner; a second control circuit means which, when energized, causes said valve to be maintained in open position, the front contact of the relay being in series with said second control circuit; an electrically operated valve means for supplying fuel to the main burner; and a circuit parallel to the relay coil for energizing said valve means.

10. In a gas heating system having a pilot burner: an electrically operated valve for controlling the flow of fuel to the pilot burner; a first control circuit means for said valve, including a timer switch and a time delay mechanism for operating said switch; means for igniting the pilot burner; and a second circuit means responsive to the ignition of the pilot burner for opening said first control circuit when the pilot burner is ignited, said mechanism having electrical means included in said second circuit means for keeping the said switch open for an interval after the pilot burner is extinguished;

11. In a gas heating system having a pilot burner: an electrically operated valve for controlling the flow of fuel to the pilot burner; a control circuit means for said valve, including a timer switch and an electrically energized igniter in series; heater means operated in response to energization of said circuit for a period to open said switch; and circuit means for short-circuiting the timer switch, comprising a circuit controller paralleling said switch; a heater having a coil in series with said circuit controller for maintaining said switch open for an interval after said circuit means becomes inactive, and means controlling the energization of the heater coil in response to variation in temperature at 12. m a heating system utilizing fluid fuel, and

having a main burner and a pilot burner; an

1 l3 electrically operated valve controlling the passage of fuel to the pilot burner; and means for reducing the supply of fuel to the main burner to an insubstantial degree before the pilot burner valve may be opened, comprising a valve for the main burner, said main burner valve having a movable closure; means for moving said closure between open and closed positions; circuit means for operating the pilot burner valve; and a controlling device for said circuit means, and operated by movement of the closure toward closlng position.

13. In a gas heating system having a pilot burner: an electrically operated valve for controlling the flow of fuel to the pilot burner; a control circuit through which the valve may be electrically operated when the circuit is completed for opening the valve; said circuit including an electrically energizable igniter for the burner; a time delay switch means having contacts and electrically energized contact operating means, both the contacts and contacting operating means being included in said circuit and operating to open the circuit after an interval of energization of the igniter; and a sec- 0nd circuit means operating to maintain the pilot valve open upon ignition of the pilot flame.

WILLIAM A. RAY.

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

UNITED STATES PATENTS Number Name Date 1,734,258 Kraft, et al. Nov. 5, 1929 2,077,297 Williams Apr. 13, 1937 2,108,770 Kriechbaum Feb. 15, 1938 2,170,497 Gille Aug. 22, 1939 2,188,565 Bower Jan. 30, 1940 2,201,328 Wallis. et a1. May 21, 1940 2,237,577 Ray Apr. 8, 1941 2,249,442 Thornbery July 15, 1941 2,263,430 Wannamaker Jr. Nov. 18, 1941 2,263,767 Fox Nov. 25, 1941 2,269,157 Levine Jan. 6, 1942 2,272,351 Polcari Feb. 10, 1942 2,272,975 Jacobs Feb. 10, 1942 2,286,156 Peterson June 9, 1942 2,290,048

Hildebrecht July 14, 1942