US2446718A

US2446718A - Thermostatic safety control for fuel burners

Info

Publication number: US2446718A
Authority: US
Inventors: William A Ray
Original assignee: General Controls Co
Current assignee: General Controls Co
Priority date: 1944-11-13
Filing date: 1944-11-13
Publication date: 1948-08-10
Anticipated expiration: 1965-08-10

Description

W. A. RAY

Filed Nov. 13, 1944 THERMOSTATIC SAFETY CONTROL FOR FUEL BURNERS M m l Aug. 10, 1948.

INVENTOR Vl l'll/om A. Ray W m ATTORNEY Patented Aug. 10, 1948 UNITED STATES PATENT OFFICE THERMOSTATIC SAFETY FUEL B This invention relates to the control of burners, such as in domestic gas ranges, and particularly to the control of the oven or broiler burners.

It is one of the objects of this invention to provide a system for igniting such burners in a safe manner, and simply by controlling an electric circuit, as by thev aid of a push button.

It is another object of this invention to provide a system of this character that automatically ensures safe conditions at the burner before fuel is free to flow, and particularly that prevents opening of the main valve until after the pilot burner is ignited.

It is another object of this invention to make it possible to control an effectively large electrical power for operating the main valve in response to the condition of theigniter. If the igniter is for some reason inoperative, the main valve cannot be opened.

It is another object of this invention to provide a simple and safe ignition system, in which the pilot burner is lighted only when the main burner is to be placed in operation, and in which an electrical igniter is used to light the pilot burner. 4

In order to simplify the design of the electromagnetic units utilized in the system, as well as to avoid undesirable chatter or hum, it is preferable to provide a source of unidirectional current for operating the valve. Since almost all sources of commercial power supply alternating current, it is thus necessary to provide a rectifier for the system.

In an application filed in the name of William A. Bay on June 8, 1944, entitled Fuel supply system and bearing Serial Number 539,377, now Patent No. 2,408,954, granted October 8, 1946, a system is disclosed in which an electronic emission device that responds to the existence of a pilot flame is utilized as the safety control device and, additionally, as a rectifier for the supply of unidirectional current for a control valve.

It is another object of this invention to provide a system embodying these features and wherein the electronic emission device serves as a safety control for the fuel supply to the pilot burner. Thus, upon failure of the pilot flame, the fuel supply to the pilot burner is interrupted. Furthermore, the electronic emission device can be used to supply power for operating the main valve, as well as for maintaining the pilot burner valve open after it is manually operated,

It is another object of this invention to make it possible safely to ignite and extinguish a fuel CONTROL FOR URNERS William A. Ray, Glendale, CaliL, assignor to General Controls Co., a corporation Application November 13, 1944, Serial No. 563,166 12 Claims. (01. 158-1111) 2 burner of this character by simply operating a start and stop button, or their equivalents.

It is another object of this invention to provide a system adapted to initiate the fuel supply to a burner, to light the pilot burner and, thereafter, to establish the fuel supply to the main burner, such operations occurrin in such rapid sequence, in response to the simple manipulation of a single control mechanism, as to fall within the normal period of holding down a Lutton.

It is still another object of this invention to provide such a system wherein failure of the pilot burner to light will prevent flow of fuel to the main burner.

It is still another object of this invention to provide such a system wherein upon failure of the pilot burner to light, as by failure of the i niter for the pilot, not only is the main valve kept closed, but the flow of fuel to the pilot burner is likewise interrupted.

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. This 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.

In the drawing:

Figure 1 is a schematic showing of a system incorporating the invention; and

Fig. 2 is a view showing a difierent operating position of one of the valves employed in the system illustrated in Fig. 1.

The system of the invention contemplates the use of a photo-emissive electronic device which is energized by a suitable source, and operated to supply current for the system by the light of the pilot flame. The response of such a device is substantially instantaneous, or at least as fast as the ignition conditions. Thus, it is proposed to energize the device to actuate an igniter, and to open the valve controlling the pilot burner, as by pressing a push button. Release of the push button serves to open the control valve for the main burner, but only if the pilot flame is burning. If the pilot flame is not burning, such release will not open the control valve and, further, will cause return of the pilot valve to closed position. Thus, the need of a constantly burning pilot flame is obviated. Further, by lighting the pilot burner 3 first and causing the control valve for the main burner to open only if the pilot flame is burning.

4 escape of any considerable amount oi unignlted fuel, such as might occur if it were attempted to light the main burner directly. is prevented.

The system may be utilized for the control of fuels generally, either gaseous or liquid. As shown, it is particularly adapted for controlling a main burner I which may be used, for example, to heat the oven or for broiling in a conventional cooking stove which utilizes gaseous fuel. The main burner I is adapted to be supplied with iuel from an appropriate source by means of a pipe 2, the flow of fuel to the burner being controlled by a main or control valve 3. A pilot burner 4 provides a flame 5 for lighting the :burner I when valve 3 is opened, and is supplied with fuel by a conduit 8 connected to pipe 2 between thecontrol valve 3 and the source of i'uel supply. In this way, the supplyoi fuel to the pilot burner is not affected by closing of the control valve 3. A pilot burner valve 1 is interposed in the conduit 8 for controlling the supply of fuel to the pilot burner 4.

The arrangement is such that the pilot flame does not burn continuously, but is extinguished when the main burner is extinguished, and lighted only when the main burner is to be lighted. Further, unless the pilot flame is burning, the control valve 3 cannot be opened; and, should the pilot flame 5 fall at any time, the control valve 3 will immediately close.

The control circuit includes a light sensitive device 8, such as a photo-tube, that responds to the light produced by the pilot flame 5. appropriate shieids (not shown) being provided to exclude light from any other source. Thus, although the main burner I, the pilot burner 4, and the light sensitive device 8 are shown for illustrative purposes as lying in the plane of .the drawing, it is preferred that the device 8 and the pilot burner 4 lie in a plane normal to the plane of burner 4 and the main burner I. In this way, the light sensitive device 8 is not exposed to the light of the main burner fiame. A fo using device 9 may be used to project light from the flame 5 into the light sensitive electrode oi he tube 8.

The contrcl valve 3 is shown diagrammatically and is of a novel type, being adapted when open to supply either a large quantity of fuel (high fire) or a small quantity (low fire) to the main burner I in accordance with the amount or heat required from the bume'r I. Such a valve is disclosed and claimed in a cc-pending application filed in the name of William A. Ray on October 28, 1944, under Serial No. 560,793 and entitled Fluid control system.

The valve 3 is shown as having a body I with an inlet chamber II and an outlet chamber I2 separated by a wall I3. The chambers II and I2 are adapted to be in communication by a port I4 extending through .the wall I3 and defined by a vertically extending tube I providing valve seats I8 and I! at its upper and lower ends respectively. A valve member I8 is provided for controlling the port I4 and includes closure membars 28 and 2I, secured together in spaced relationship by a stem 22, which cooperate respe tively with sea-ts I3 and I! to close the port I4. When the valve member I3 is in its lowest position, the closure 28 is on its cooperating valve seat I5, closing the port I4 and preventing any communication between the chambers II and I2. This is or course the closed position oi the valve 3, and i indicated by broken lines in Fig. l.

When .the valve member I8 is in its upper position, closure member 2I is on its cooperating valve seat II, also closing port I4 but communication between chambers II and I2 is maintained by a reduced port 23 between port I4 and the outlet chamber I2. This is the low fire position oi! the valve and is shown in Fig. 1. With the valve member I8 in an intermediate position both closure members 20 and 21 are sufiiciently spaced from their respective seats I8 and I! to allow tree communication between the chamber II and I2 via port I4. This is the high fire position or the valve and is shown in Fig. 2.

Means are provided whereby the valve 3 is caused to open and to close in accordance with energization or de-energization of a controlling circuit. Further means are provided by which valve 3 assumes the low fire or high fire position in accordance with the heat requirements of the system. Thus the upper wall of the inlet chamber II is formed by a flexible diaphragm 24 to which is secured the valve member I8. A similar diaphragm 25 is secured in body II above the diaphragm 24 and cooperates with the body III and the diaphragm 24 to form a pressure chamber 28. The diaphragm 25 forms the :lower wall of a working chamber 2I in the body I8.

The diaphragms 24 and 25 are maintained in spaced relation by a member 88 fixed on t der side of diaphragm 25 in axial alinement with the valve member I8 and having a projection 3i adapted to engage the top of diaphragm 24. The member 38 also has an extension 32 projecting upwardly through the diaphragm 25 and forming a clevis .to which is pivoted one end or a link 33. The other end of the link 33 is pivoted .to a depending arm 34 of the operating lever 35, pivotally supported at 38 in the body I8, and urged downwardly about its pivot 38 by a compression spring 81.

A charged Sylphon or expansible chamber 38 supported in body I8 serves by engagement with arm 34 to determine the position of lever 35 about its pivot. The Sylphon 38 forms one'elemerit of a conventional pressure responsive system 39 and for this purpose is connected by means of capillary tube 48 with a feeler bulb H in thermal relation with the space or object arranged to be heated by fuel passed by the valve 3 and the temperature of which it is desired to control. A second expansible chamber or Sylphon 42 is also connected to the capillary tube 40 and is adjusted to a desired volume by an adjusting knob 43. By adjustment of the volume of chamber 42, the position of lever 35 for any given temperature at the feeler bulb 4I may be altered. The knob 43 may be provided with an appropriate scale to assist in such adjustment, and may be marked in-temperature degrees. A stop pin 44 serves to limit movement of lever 35 in response to a lowered temperature, that causes Sylphon 38 to contract and pull lever 35 downwardly.

An operating or pilot valve 45 is provided for controlling the pressures in chambers 25 and 21 and causing the valve 3 to open and to close. Valve 45 includes a fluid tight casing 41 in continuous communication with pressure chamber 25 as by a conduit 48. Casing 41 is arranged to be vented to the atmosphere or provided with fiuid under pressure from the pipe 2 by a pair of spaced oppositely directed nozzles 48 and 58. Nozzle 48 communicates with the exterior oi. casing 41 as by a vent tube 5|, while the nozzle 58 communicates with the pipe 2 by tube 52.

A member 53 is pivotally supported at 54 in casing 41 for angular motion between the nozzles 49 and 58, being biased as by a tension spring 55 to a position in which it closes the vent nozr zle "and opens the inlet nozzle 58. An elec-q tromagnet 58 is provided to act on member 53 in opposition to the spring 55. For this purpose, member 53 is a magnetic armature. Thus upon energization, magnet 56 swings member 53 to a position in which the vent nozzle 5| is open and inlet nozzle 58 is closed. The working chamber 21 is under fluid pressure at all times through the connection 51 to the tube 52.

The operation of the control valve 2 may now be set forth. The position of diaphragm 25 is determined by lever 35 in accordance with the temperature requirements of the system independently of pressure conditions in the valve 3. With magnet 56 de-energized, vent 48 is closed and fluid pressure from the pipe 2 is present in casing 41 and pressure chamber 28, where it serves to maintain diaphragm 24 in its lower position with closure 28 of valve member l8 on seat I6, thus preventing passage of fuel through valve 3. Upon energization of magnet 56, member 53 swings to vent casing '41 and chamber 26 to the atmosphere, so that the pressure of the i'uel below diaphragm 24 urges the diaphragm and valve member i8 upwardly until stopped by engaging the projection 3| carried by diaphragm 25. I! the temperature requirements of the system are such that a low fire is all that is required, lever 35 will be so positioned that projection 3| does not engage the diaphragm 24, hence the diaphragm and valve member Hi can move to their upper position allowing memebr 2| to seat. Thus fuel is supplied to burner I only by the reduced port 23, as shown in Fig. 1. If, however, a high fire is required, lever 35 will be so positioned that projection 3| stops diaphragm 24 and valve member l8 at an intermediate position in which both

closures

20 and 2| are unseated, giving a full valve opening. Upon de-energization of magnet 56, pressure will be re-established in chamber 26. Pressures on opposite sides of diaphragm 24 are thus equalized and the diaphragm 24 is moved downwardly by the weight of valve member i8 to cause closure 20 to seat and prevent passage of fuel to the burner I. The transition of the valve member l8 from high fire to low fire position, or vice versa can, or course, occur at any time while the valve is open and the main burner l in operation.

The main burner I is arranged to be lighted by the actuation of a push button mechanism 60 and through the intermediary of a pilot burner. Thus, when the push button is pressed, the pilot burner is lighted. When the push button is released, if the pilot burner is burning, the control valve 3 will be opened. If the pilot burner has failed to light, the control valve 3 will remain closed and the pilot burner valve will close.

The pilot burner valve 1 comprises a spring pressed closure member having a projection or stem 8| which when pressed opens the valve. A bell crank 62 pivoted at 63 serves by clockwise movement about its pivot to open the valve 1. The upper end of bell crank 62 carries a roller 65 which engages the face of a magnetic armature B6. The-armature 68 is adapted to be moved to and from engagement with the polar faces of an electromagnet 61. When armature 68 is in engagement with the magnet 81 as shown, or in attracted position, valve I will be open. If no force is present to maintain armature 66 in this position, armature 88 and arm 82 will be returned to the broken line position and valve 1 will close, in response to force exerted by the springin the valve, supplemented if desired by a tension spring 58.

The armature 88 has a push rod 69 with a convex outer end I8 adapted to be engaged by the inner end of a push button or actuating member II. A light compression spring 12 is confined between flanges and 14 respectively on push rod 68 and push button II for urging the push rod and the push button axially apart. However, it is to be understood that spring 12 does not have suflicient strength to move rod 68 and armature 88 toward magnet 81 in opposition to the force exerted by spring 88. Spring I2 is merely for the purpose of returning the push button H to its initial position when released, it the armature 88 isflretained in its attracted position by magnet A switch arm 11 is attached to push rod 89 and carries a. contact 18 adapted to engage a stationary contact 19 when armature 66 is in engagement with magnet 81. A similar switch arm 88 carrying a contact 8| is arranged to be moved to engage a stationary contact 82 when push button II is depressed to move armature 88 to engage the magnet 51. Contacts 8| and 82 are separated upon return of push button H to its initial position. Similarly

contacts

18 and 19 separate upon movement of armature out of engagement with magnet 61. Another arm 83 carries a contact 84 which engages a fixed contact 85 when the push button H is in its initial or normal position,

contacts

84 and 85 separating when push button ll is depressed. The operation of the push button mechanism will be explained after a discussion of the control circuit.

The control circuit includes the phototube 8 which is energized by an alternating current source and is operative to supply current to the circuit only as long as the pilot flame 5 is burning.

The phototube 8 serves, in addition, as an electronic emission rectifier for supplying unidirectional current to the electromagnet 61 for maintaining the pilot burner valve 1 open and to magnet 56 which serves to open and maintain open the control valve 3. If the pilot flame is not burning, no current is delivered by the phototube 8 and valves 3and i are not maintained open. Accordingly the photube 8 performs a plurality of functions: it not only serves as a control device, but also provides rectified current for the system.

It is preferred that the phototube 8 supply sufllcient current for the electromagnets 58 and 81 without the use of an amplifier. Accordingly, the tube 8 is shown as of the electron multiplier type. for example of the type known as 931-A. Such a tube includes a photo-sensitive cathode 88 which emits electrons when its active surface is illuminated, as by the flame 5. The anode 89 finally receives the electrons produced in the tube by successive action of the electrons upon a number of auxiliary electrodes or secondary emitters 90, BI, 92, 83, 94, 85, 96, 81 and 98, nine being shown in the present instance. In order that these electrodes serve effectively to reinforce, by secondary emission, the original electronic stream emanating from the cathode 88, they are connected to taps on the secondary winding 99 of a step up transformer I80. The primary winding I8! is adapted to be connected to a commercial source of alternating current by leads I82 and The operation of a tube of this character is well known. A relatively weak stream of electrons is dislodged from the photo-sensitive surface of the cathode 88, which stream is greatly reinforced by secondary emission successively from the auxiliary electrodes 88 to 88 inclusive, which are successively encountered by the electron stream. The output current between the anode 88 and the cathode 88 is unidirectional, and the maximum of which the device is capable.

Accordingly, the coil of the electromagnet 58 of valve 48 is connected between anode 88 and cathode 88, since this magnet is required to move member 53, to attracted position as well as to retain it in such position. This circuit includes the normally closed

contacts

84 and 85, so that.

it is broken if the push button H is not in its normal position, and may be traced as follows: from anode 88, lead I88 to contact 85, contact 84, switch arm 83, lead I81, through coil 58, lead I88, to the upper terminal of the transformer secondary 88, thence through the secondary 88 to cathode 88. Since the electromagnet 81 is called upon to perform only a holding function, less than the maximum current from the tube 8' will suflice. Accordingly, it may be connected between one of the auxiliary electrodes and its tap on the transformer. Thus the coil or magnet 61 is interposed in the lead between auxiliary electrode 88 and its tap I88.

Since an important feature of the invention is the fact that the control circuit is de-energized when the main burner I is not burning, means are provided for opening the circuit to the transformer primary I8I when the main burner I is extinguished. For this purpose the contacts 18- and 18 are interposed in one of the leads as I83 which supplies the transformer primary. Thus the transformer I88 and tube 8 are energized only when armature 88 is in its attracted position.

Further, since the pilot flame is extinguished whenever the main burner I is extinguished, means are provided for lighting the pilot burner 4 when it is desired to open the control valve 3. For this purpose. an igniter I I8 is provided, which may be of any preferred type, as spark or hot wire, and is arranged to be activated upon opening the pilot burner valve 1. Thus the ignlter I I8 is connected across leads I82 and I83 by a circuit including the normally open contacts 8| and 82 so that the igniter I I 8 is operated only when the push button H is depressed. This circuit may be traced as follows: from lead I82, lead III, igniter II8, lead II2, contact 8|, contact 82, lead II3 to lead I83.

The operation of the system as a whole will now be dlscussed. Assuming that the system is not operating, armature 88 will be in its retracted position indicated by the broken lines and switch

contacts

18, 18 will be open, pilot burner valve I will be closed, member 53 will be in the broken line position, and the closure I8 of the main valve 3 will be in its closed, broken line position (Fig. 1). Push button H is now depressed to move armature 88 to its attracted full line position. This opens the pilot burner valve 1, closes contacts 18-18 energizing the phototube 8, closes contacts 8I-82, energizing the igniter H8, and opens contacts 84-85. The pilot burner 4 lights very soon thereafter, causing tube 8 to energize the control circuit including the electromagnet 81 thus maintaining armature 88 in attracted position and holding the pilot burner valve 1 open and contacts 18-18 closed. However, the

valve 8 controlling the main burner cannot open due to contacts 84-85 being separated.

The response of the phototube is practically instantaneous. Hence as soon as the pilot burner 4 lights, the control circuit is energized and push button 1I may be released. It is then returned to its initial position by spring 12 leaving armature 88 in its attracted position. This opens contacts 8I-82 de-energizing the igniter, and closes contacts 84-85 energizing coil 58, which opens themain valve 8 as previously explained.

When it is desired to extinguish the main burner I, the entire control circuit is de-energized by opening the circuit of the transformer primary I8 I. This may conveniently be done by operating a normally closed push button actuating switch II4.

If the pilot burner 8 fails to light, the phototube 8 cannot energize the control circuit. Hence, when push button H is released, armature 88 returns to its retracted position, allowing the pilot burner valve 1 to close and de-energizing phototube 8 by opening contacts 18-18.

In view of the fact that the system utilizes an electronic emission device 8 for supplying current to the manual reset electromagnet 81 and the valve operating electromagnet 58, the automatic process of checking the safety circuits upon pressing button H is very rapid. Accordingly, the button need be held down only for a short period, usually less than a second, and under no circumstances more than two or three seconds. This checking period is considerably less than the period of time that the ordinary person would be expected to hold down a button.

The electrical switching mechanism, including the push button mechanism 88, is made the subject matter of a divisional application No. 1,526, filed January 10, 1948, for Interlocking safety switch system.

The inventor claims: 1. In a system of the character described, main burner, a pilot burner, an electrically operated valve controlling the flow of fuel to the main burner, means for igniting the pilot burner, and means responsive to light radiations from the pilot flame for transmitting electrical energy to the electrically operated valve, comprising a photoelectric tube having an electron emitting cathode upon which the light of the pilot burner is arranged to be cast.

2. In a system of the character described, a main burner, a pilot burner, an electrically operated valve controlling the flow of fuel to the main burner, means for igniting the pilot burner, and means responsive to light radiations from the pilot flame for transmitting electrical energy to the valve, comprising a multiplier phototube rendered active by the light of a pilot flame, and a circuit for operating said valve, said circuit including the phototube and a circuit controller for completing the circuit, and capable of being retained in active position by energy derived from the phototube.

3. In a system of the character described: a pilot burner for producing a pilot flame; a main burner; a control valve for the main burner; a valve for the pilot burner; an electronic emission device adapted to be energized by a source of alternating current, and activated by the pilot flame; means forming a circuit in which current from said device operates to hold the control valve open; an actuator having a pair of relatively movable parts, one of said parts being biased to an inactive position, said actuator,

when operated, serving through both said parts to open the pilot burner valve, said one part being returnable to its inactive position independently of said pilot burner valve; means operating on the other part for maintaining said pilot burner valve open by current from said device; and means for conditioning said circuit for the control valve for a holding operation only when said one part is in its initial position.

4. In a system of the character described: a pilot burner for producing a pilot flame; a main burner; a control valve for the main burner; a valve for the pilot burner; an electronic emission device adapted to be energized by a source of alternating current, and activated by the pilot flame; means forming a circuit in which current from said device operates to hold the control valve open; an actuator having a pair of relatively movable parts, oneof said parts being biased to an inactive position, said actuator, when operated, serving through both said parts to open the pilot burner valve, said one part being returnable to its inactive position independently of said pilot burner valve; means for connecting said device with said source upon opening the pilot burner valve; means operating on the other part for maintaining said pilot burner valve open by the current from said device; and means for conditioning said circuit for the control valve for a holding operation only when said one part is in its initial position.

5. In a system of the character described, a pilot burner for producing a pilot flame, a pilot burner valve, a member movable between retracted and attracted positions and serving when in attracted position to maintain said valve open, means urging said member to retracted position, means for maintaining said member in attracted position, a device for supplying unidirectional current to said means and adapted to be energized by a source of alternating current, and activated by the pilot flame, means connecting said device with said source only when said member is in its attracted position, an actuator movable from an initial position for moving said member to attracted position and freely returnable to its initial position, means urging said actuator to its initial position, a main burner, a control valve for said burner, a circuit for causing said control valve to open when the circuit is energized, and means connecting said circuit for energization by said device only when said actuator is in its initial position.

6. In a system of the character described, a pilot burner for producing a pilot flame, a pilot burner valve, a member movable between retracted and attracted positions and serving when in attracted position to maintain said valve open, means urging aid member to retracted position, means for maintaining said member in attracted position, a device for supplying unidirectional current to said means and adapted to be energized by a source of alternating current, and activated by the pilot flame, means connecting said device with said source only when said member is in its attracted position, an actuator movable from an initial position for moving said member to attracted position and freely returnable to its initial position, means urging said actuator to its initial position, an igniter for said pilot burner, means whereby movement of said actuator from its initial position to move said member to attracted position activates the igniter, a main burner, a control valve for said burner, a circuit for causing said control valve to open when the circuit is energized, and means connecting said means for initiating the operation of said ignition means, said movable means having a member retnming to a beginning position after operation of said movable means ceases, circuit means including an electronic emission device operating substantially instantaneously upon successful operation of the ignition means, said circuit means also including a circuit controller maintained in active position by power derived from the output side of the electronic emission device, said circuit controller energizing said valve, and another circult controller for the valve operated to active position upon return of the said member to the beginning position, and interrupting flow of power to operate the valve until said return takes place.

8. In a system of the character described: an electronic emission device; a pilot burner for producing a flame activating the device; a valve governing flow of fuel to the burner, said valve being normally biased to closed position; means for actuating the valve to open position; electric means energized by said device for maintaining said valve in open position when the actuating means is rendered inactive; and means controlled by said actuating means for connecting said device to a source or electric power.

9. In a system of the character described: an electronic emission device of the light responsive typ a pilot burner for producing a flame whose luminosity activates the device; a valve goveming flow of fuel to the burner, the valve being normally biased to closed position; electromagnetic means energizable by the device; manually operable means including an armature for actuating the valve to open position; and means controlled by the manual means for connecting the device to a source of electric power; the armature being retained in operative attracted position by the electromagnetic means, thereby checking the existence of the flame.

10. In a system of the character described: a main burner; a pilot burner; means for igniting the pilot burner; manually operable means, having a pair 01' relatively movable parts, one of said parts being normally biased to inactive position, for operating said igniting means, as well as for supplying fuel to the pilot burner; apparatus activated by the flame of the pilot burner, in-

cluding safety means for maintaining the supply of fuel to the pilot burner after said part is restored to inactive position; a valve for the main burner; and electrically operated means for operating the valve for the main burner to open and closed position, and energized by said apparatus.

11. In a system of the character described: a main burner; a pilot burner a valve for the main burner; means for igniting the pilot burner; manually operable means, having a pair of relatively movable parts, one of said parts being normally biased to inactive position, for operating said igniting means, as well as for supplying fuel to the pilot burner; electrically operated means for operating the valve to open and closed position, and energized by said apparatus; and means ensurlng that said valve remains closed while said part is active.

12. In a system of the character described: a main burner; a pilot burner; means for igniting 11 the pilot burner; manually operable means, having a pair of relatively movable parts, one of said parts being normally biased to inactive position, for operating said igniting means, as well as for supplying fuel to the pilot burner; a photoelectric cell influenced by the flame of the pilot burner for supplying power to maintain the supply of fuel to the pilot burner when said part is restored to inactive position; a valve for the main burner; and means operated by power derived from said cell for operating the valve for the main burner to open and closed position.

- A. RAY.

' REFERENCES CITED UNITED STATES PATENTS Name Date Gauger July 9, 1935 Number Number 2,077,291 2,081,091 2,198,453

12 Name Date 'Williams Apr. 13, 1937 Kuempel May 18, 1937 Manta Apr. 23, 1940 Grayson May 21, 1940 Betz, et a1 Oct. 15, 1940 Ray Apr. 8, 1941 Wyman Sept. 9, 1941 Beam Mar. 3, 1942 Crary June 2, 1942 Snyder, Jr July 21, 1942 Denison Aug. 4, 1942 Eskin Sept. 22, 1942 Pi'leger Dec. 1, 1942 Jones Dec. 8, 1942 Metcalt Dec. 22, 1942 Jones Mar. 28, 1944 Schumann, et al. Oct. 10, 1944 Eskin Aug. 14, 1945