US3026927A

US3026927A - Device for the control and selection of fuel to a burner

Info

Publication number: US3026927A
Application number: US855089A
Authority: US
Inventors: Matheis Theodore; Jr Charles T Alverson
Original assignee: Foster Wheeler Inc
Current assignee: Foster Wheeler Inc
Priority date: 1959-11-24
Filing date: 1959-11-24
Publication date: 1962-03-27
Anticipated expiration: 1979-03-27

Description

March 27, 1962 MATHEIS ETAL DEVICE FOR THE CONTROL AND SELECTION OF FUEL TO A BURNER 2 Sheets-Sheet 1 Filed Nov. 24, 1959 IWNTORS Ova/u g; Z AMVERJO JR.

' ATTORNEY March 27, 1962 MATHEIS ET AL 3,026,927

DEVICE FOR THE CONTROL AND SELECTION OF FUEL TO A BURNER Filed Nov. 24, 1959 2 Sheets-Sheet 2 INVENTORS 771000RE MA THE/5' OW-M ATTORNEY United States Patent 3 026,927 DEVICE FOR THE CJJNTROL AND SELECTIGN OF FUEL Tf) A BURNER Theodore Matheis, West Islip, N.Y., and Charles T. Alverson, Jr., Sommerville, N.J., assignors to Foster Wheeler Corporation, New York, N.Y., a corporation of New York Filed Nov. 24, 1959, Ser. No. 855,089 13 Claims. (Cl. 158-28) This invention relates to burners firing combustible fuels and more particularly to the control and selection of the fuel to such burners.

In many of the larger sized furnaces which employ multiple burners firing combustible fuels, a flame detector device is provided to arrest the flow of fuel to the burner in the event of failure of the burner flame. As is known, the explosion hazard resulting from flame-out of the burner is due principally to the fact that the un-ignited fuel continues to enter the combustion chamber and subsequent ignition of such accumulated fuel causes the explosion. Many furnace installations employ radiant energy sensitive elements, as for example, lead sulfide cells, photo electric cells or the like which are provided with access to the flame area of the burner and such elements are connected in circuit with electrically operated fuel control valves. In the event the burner flame is extinguished, for any reason, the radiant energy sensitive element senses the absence of the radiant energy from the flame and, consequently, effects actuation of the fuel control valve to the closed position to arrest flow of fuel to the burner and into the combustion chamber.

In practice, it is found that most radiant energy sensitive elements require shields with radiant energy restricting or modulating means to operate properly when a fuel, as for example, oil is used, because the intensity of radiant energy resulting from the oil flame is so great as to cause saturation of the sensitive element and thereby effect erratic operation, or inoperativeness, of the fuel control valves. As is well known, the sensitive element generally functions to insert a control signal or resistance in the control circuitry for the fuel valves and the impingement of the radiant energy upon the sensitive element from the burner flame causes a variation in such signal or resistance to thereby effect operation of the fuel valves. When it is desired to detect the infra-red portion of the spectrum a sensitive element as for example a lead sulfide cell is used, whereas a sensitive element such as a Geiger counter is used when the ultra-violet portion of the spectrum is to be detected. Since the actuation of the radiant energy sensitive element is a function of the amount of radiant energy received, or the intensity of the radiant energy impressed thereon and of the area exposed to such energy, saturation of the element is obvi ated by the use of shields having optical filters with lenses of required opaqueness or pre-determined size orifices which reduce the amount of flame radiant energy impinging on the radiant energy sensitive element. Thus, in the case of a high intensity radiant energy flame such as an oil flame, a small sized orifice or optical filter of higher opacity is utilized to reduce the radiant energy to the sensitive element whereas in the case of a reduced intensity radiant energy flame, a larger size orifice or filter of lower opacity is employed to increase the amount of radiant energy to the sensitive element. When, for example, the flame detector is used with a burner capable of firing a different fuel and/or combinations thereof, having different intensities of radiant energy, a plurality of shields each having a different size orifice or optical filter is required. Thus, if the burner is firing one fuel and it is desired to switch over to another fuel having a different intensity, or a combination of the fuels, the

3,026,927 Patented Mar. 27, 1962 flame must be extinguished so that the shield then in use is replaced by another shield having the proper size orifice or optical filter, for the fuel to be burned. Accordingly, the fuel control valves are actuated to closed positions and the shield is manually replaced with the required optical filter or an orifice of the proper size. In such case, it is not unusual for an operator to forget to either change the shield or to change over to the fuel to be used, in which event, further delays are encountered.

It is an object of the present invention to provide a novel control arrangement for effectively controlling the flow of fuels and selection of same to a burner, or burners.

The present invention therefore, contemplates a novel fuel selector and safety control for a multi-fuel firing burner and comprises a housing which is constructed to accommodate a radiant energy sensitive element and a sighting tube for effecting transmission of radiant energy to the sensitive element from a burner flame area. Shutter means are provided for intercepting or restricting the radiant energy from a burner flame and the shutter means includes either optical filters for varying the amount of radiant energy or orifices for varying the amount of surface area of the sensitive element exposed to the flame radiant energy. The housing also contains a multi-fuel selector control which effects the flow of one or more fuels to a burner. The shutter means and the selector control are interconnected for simultaneous operation whereby operation of the selector control to effect flow of a fuel to the burner automatically presents an optical filter or orifice corresponding to the fuel or fuels to be used, to the radiant energy sensitive element.

The above and other objectives and advantages of the present invention will appear more fully hereinafter from a consideration of the detailed description which follows taken together with the accompanying drawings wherein one embodiment of the invention is illustrated.

In the drawings, wherein the like characters refer to like parts throughout the several views:

FIG. 1 is a front elevational view of a control housing which incorporates an embodiment of the present invention;

FIG. 2 is a sectional view taken along the line 22 of FIG. 1;

FIG. 3 is a sectional view taken along the line 3-3 of FIG. 2 and is on an enlarged scale to more clearly illustrate certain parts thereof;

FIG. 4 is a diagrammatic representation of the fuel selector arrangement in conjunction with fuel control valves; and

FIG. 5 is an elevational view of a switch actuating disc used with the switch assembly shown in FIG. 2.

Referring now to the drawings for a more complete understanding of the invention and more particularly to FIG. 1, the reference character 11 designates a control housing which includes a detachable front cover 15, a back wall 17 (FIG. 2) and

side walls

19 and 21, respectively. Detachable cover 15 is secured by threaded members 23 and has fixed thereto a tubular member 25 which has an internal diameter of sufiicient size to accommodate a radiant energy sensitive element as for example, a lead sulfide cell or a Geiger counter 27. Sensitive element 27 is secured within tubular member 25 by a threaded and knurled cap member 29. A sighting tube 31 cooperates with element 27 to define an access path or line of sight for the element 27 to the flame area of a burner (not shown). Sighting tube 31 includes a tube section 33 which is secured to back wall 17 of housing 11 and such tube section extends to and immediately adjacent tubular member 25 and in alignment with the latter. A portion of tube section 33 extends away from back wall 17 and has a threaded end 35 which is joined to a second tube 37, generally forming part of sighting tube 31, by a coupling member 39. Tube section 37 is adapted to extend into the combustion chamber (not shown) of a furnace (not shown) and is adapted to sight the flame area of a burner (not shown).

Fuel selector control means 45 is provided on front cover and includes a manually operable control knob 47 mounted for rotation in a sleeve 49 having an externally threaded portion 51 and a flange portion 53 which extends behind cover 15 (FIG. 2). A knurled locking member 55 having an internal threaded portion 57 cooperates with the threaded portion 51 of sleeve 49 to secure the sleeve on front plate 15. Knob 47 is movable, to either side of a middle position, as seen in FIG. 1, and thus may be rotated to any one of three positions as will be described hereinafter. When knob 47 is rotatcd in a counterclockwise position from that shown in FIG. 1, flow of a fuel such as oil is intended to be eflected to a burner (not shown), and when rotated in a clockwise direction to the opposite and extreme position the flow of a different fuel such as gas to the burner (not shown) is intended to be effected. When control knob 47 occupies the middle position, a combination of two fuels such as both oil and gas is intended to be effected to the burner (not shown). Control knob 47 has a shaft 59 (FIG. 2) which extends centrally of sleeve 49 and has secured thereto a switch actuating disc 61. Disc 61 has a contoured or cam surface 63, which bears against a rectangular-shaped fiat plate 65 (FEGS. 2 and 3) having a flange portion 67 extending at right angles to the plate and toward cover 15.

Supported behind plate 65 looking towards the rear of housing 11 is a switch assembly block 69 which contains an upper switch 71 and a lower switch 73. Only switch assembly 71, in broken lines, appears in FIG. 2 by reason of the vertical arrangement of switches in block 69. Switch 71 comprises a spring-biased plunger 75 which is urged towards plate 65 and carries a pair of bridged button contacts 77 adapted for engagement and disengagement with a pair of stationary button contacts 79. Switch 73 is identical in construction to switch 71 and includes a spring biased plunger 81 shown only in FIG. 3, and includes corresponding bridged button contacts 77 and stationary button contacts 79. Each of the stationary button contacts 79 of the

switches

71 and 73 have connected thereto lead-in terminals 83 which may have connected thereto wires (not shown) and extending outside housing 11 through a conduit 85 on side wall 21 of housing 11. Plungers 75 and 81 of

switches

71 and 73, respectively, are disposed in alignment with

openings

87 and 89 formed in plate 65 whereby the plungers project through such openings when urged by their respective springs towards control knob 47. It will be apparent from the drawings that switches 71 and 73 are normally closed and that the ends of their respective plungers extend through and on the other side of plate 65 and in the path of movement of cam surface 63 of switch actuating disc 61. Thus, in the position shown in FIG. 3 cam surface 63 engages neither plunger and the control knob 47 is in its middle position as shown in FIG. 1. In this position of control knob 47 both sw'

ches

71 and 73 are closed. Rotation of knob 47 in a counter-clockwise direction from the position causes cam surface 63 to engage and depress plunger 75 thereby opening its switch 71. On the other hand, movement of knob 47 in a clockwise position from that shown in FIG. 1 causes cam surface 63 to engage and depress plunger 81 of switch 73 thereby opening such switch.

The operation of the fuel selector control of the present invention may be more clearly understood by reference to FIG. 4 wherein a diagrammatic representation of such selector control is disclosed. The diagrammatic representation of

switches

71 and 73 is not a true representation thereof but is modified somewhat in FIG. 4 in order to more clearly illustrate the operation of same in connection with the present invention. For example, movable contact arms 91 and 93 correspond to plungers and 81 and the movement thereof is changed from rectilinear movement to rotary movement. In addition, shaft 94 now takes the place of cam surface 63 in actuating the switches. Stationary contacts 79 of both

switches

71 and 73 are disclosed as being mounted on

insulated plates

95 and 97 of

switches

71 and 73, respectively. A common lead connection 99 is connected to both arms 91 and 93 and to a source of electric energy. As seen in FIG. 4, wires 101 are connected to stationary contacts 79 and in turn to a wire 103 connected to the energizing coil (not shown) of a solenoid 105, shown schematically. Solenoid 105 is connected for operating a fuel control valve 107 disposed in a fuel conduit 109. The stationary contacts 79 of switch 73 have wires 111 connected thereto and in turn connected to a lead 113. The energizing coil (not shown) of a solenoid shown schematically is connected to lead 113 and such solenoid is adapted to operate a fuel control valve 117 disposed in a conduit 119. Conduit 109 is connected to a source of combustible gas (not shown) while conduit 119 is connected to a source of oil (not shown). The present invention contemplates an arrangement of such conduits 109 and 119' in a manner that each conduit is connected to its respective port of a single burner (not shown), firing either gas or oil, or a combination of the two.

Considering the operation of the arrangement of FIG. 4, if it is desired that the burner fire oil alone, control knob 47 is rotated in a counter-clockwise direction where by arm 91 moves upwardly and out of engagement with contact 79. Concurrently, arm 93 of switch 73 also moves upwardly out of engagement with the lower contact 79 and into engagement with the upper contact 79' as seen in FIG. 4. As a result, only solenoid 115 is en-- ergized to open valve 117 to thereby permit flow of oil through conduit 119 to the burner (not shown). Con-- versely, if it is desired to supply gas alone to the burner, control knob 47, as seen in FIG. 4, is rotated in a clockwise direction whereby arm 91 of switch 71 moves downwardly into engagement with the lower contact 79 while arm 93 of switch 73 also moves downwardly and out of engagement with lower contact 79. Accordingly, only solenoid 105 is energized to open valve 107 to thereby permit gas to flow through conduit 109 for firing by the burner. When it is desired to fire both oil and gas the control knob 47 is in the position shown in FIG. 4 and consequently both

solenoids

105 and 115 are energized to open their respective valves to thereby permit flow of both gas and oil to the burner.

As was indicated hereinbefore, radiant energy sensitive elements, as presently used, detect the presence or absence of a flame in the combustion chamber of a furnace and require the use of shields with radiant energy restricting means to prevent saturation or inoperativeness of the sensitive elements. Also, as indicated hereinbeforc, the present invention contemplates the provision of simultaneous presentation of the proper optical filter or orifice to the radiant energy sensitive element with the selection of different fuels to a burner. Since the structure of the present invention to be described is applicable generally to radiant energy restricting or modulating means, or radiant energy passages of selective capacity which include both optical filters and orifices, the following description will be restricted to one of such means to avoid repetition of description. The description which follows discusses the use of orifices in the structure rather than optical filters. It is to be expressly understood, however, that the present invention is not restricted to the use of orifices alone but is readily adaptable or usable with optical filters. In fact, the orifice may be considered in one sense an optical filter in that it may be used to filter or restrict passage of radiant energy. Accordingly, in the claims where means forming radiant energy passages of selective capacity is used, it shall be construed. to in' clude either an optical filter having a semi-opaque lens or an orifice.

Novel shutter means 121 is provided and comprises a pivotal shield member 123 and the plate 65. Shield 12-3 is mounted for pivotal movement about a pivot pin 125 secured to flange portion 53 of sleeve 49 and flat plate 65. A slot 127 is formed at one end of shield 123, ad jacent switch actuating disk 61, and such slot is dimensioned to receive an actuating pin 129. Pin 129 is secured to an arm 131 (best shown in FIG. 3) which in turn is secured to shaft 59 of control knob 47 by a rivet 133. The other end of shield 123- lies adjacent and between sensitive element 27 and tube section 33 of sighting tube 31 and has formed therein an orifice 135 (FIG. 3) and a second orifice 137 of slightly smaller diameter than orifice 13 Plate 65 also has formed therein an orifice 139 which is in alignment with tube section 33 and tube 25 containing the sensitive element 27, orifice 139 having the largest opening of said orifices. It will be evident from the drawings that when control knob 47 is rotated in a counter-clockwise direction from the position shown in FIG. 1, arm 131 secured to shaft 59 of the control knob moves actuating pin 129' also in a counter-clockwise direction to cause pivotal movement of shield 123 in a clockwise direction thereby bringing orifice 137 in alignment with tube section 33 and tubular member 25. When knob 47 is rotated in a clockwise direction from the middle position shown in FIG. 1, actuating arm 131 moves in the same direction to effect movement of shield 123 in a counter-clockwise direction thereby displacing the shield completely away from tube sec tion 33 and tubular member 25 whereby orifice 139 is in unobstructed alignment with photoelectric tube 27. When control knob 47 is in the middle position seen in FIG. 1, orifice 135 in shield 123 is in alignment with tube section 33 and tubular member 25.

Sleeve 49 has secured thereto an annular spring member 141 (FIG. 2) which carries a pair of diametrically opposed rivets 143 which are adapted for seating in scalloped portions 145 (FIG. 5) disposed about the periphery of switch actuating disc 61. The purpose of rivets 143 and scalloped portions 145 is to determine the three positions of control knob 47 and to maintain same in such position when the knob has attained same. In practice, however, when the knob 47 has been rotated to one of its three positions a certain amount of play exists and since any motion of shaft 59 of knob 47 is greatly amplified in the end of shield 123 adjacent the sensitive element 27, improper alignment of the orifices with the sensitive element may result. To overcome the foregoing condition, a flexible wire 147 is provided and has the ends thereof secured to the plate 65. An intermediate portion 148 of wire 147 is adapted to engage an indented edge 14-9 of shield 123 in its proper position when the latter is brought to such position by movement of the control knob 47. Similarly, the upper and lower portions 150 and 151 of shield 123 adjacent such end are properly shaped to cooperate with intermediate portion 14-8 of wire 147 to positively maintain shield 123 in the other positions to which the shield has been rotated. By reason of the foregoing construction, any play of knob 47 is obviated by the configuration of the flexible wire 147 and shield 123.

Considering now the operation of the arrangement described above, let it be assumed that housing 11 is mounted in the proper position on the furnace so that sighting tube 31 is directed toward the flame area of a burner capable of firing a plurality of fuels either singly, or in combination. Further, let it be assumed that sensitive element 27 is connected in circuit with the valves which control the flow of the fuels to the burner and such element inserts the requisite resistance or control in the circuit to maintain flow of fuel to the burner with presence of a burner flame, and to affect operation of the fuel valves to cut-ofl'f flow of fuel to the burner upon absence of the burner flame. Assuming that the flow of fuel to the burner is oil, control knob 47 is in a position to the left of the middle posit-ion as seen in FIG. 1 and in alignment with the legend OIL on cover plate 15. In this position of the knob 47, shield 123 has been rotated upwardly from the position shown in FIGS Whereby orifice 137 is in alignment with orifice 139 in plate 65 and with sighting tube 31 and photoelectric tube 27. Under this condition of operation, switch 73 is closed to energize solenoid 115 thereby opening valve 117, while switch 71 is opened and solenoid is de-energized to maintain valve 107 in a closed position. It will be understood that the smallest sized orifice 137 is used in this instance and corresponds with the OIL position on front cover 15. Inasmuch as the radiant energy from the oil flame is of high intensity and to prevent saturation of the radiant energy sensitive element, a minimum amount of radiant energy is transmitted to the element in order to avoid erratic control of the element 27 in the circuit. In the event it is desired to change over from oil to a combination of both oil and gas, control knob 47 is rotated from its last position to the Both position on.

so that both switches are closed. Accordingly, solenoids 105 and have actuated their respective valves 107 and 117 to effect flow of both gas and oil to the burner for firing. Simultaneous with movement of knob 47 to the middle position shown in FIG. 1, shield 123 occupies the position shown in FIG. 3 and orifice 135 now is in alignment with the sighting tube 31, orifice 139 and sensitive element 27. Since the burner now is firing a combination of oil and gas, the intensity of radiant energy produced by the resulting flame is less than that resulting from the oil flame alone and, consequently, the intermediate size orifice 135 is presented to the sensitive element to allow a greater amount of radiant energy thereto from the flame. In firing the burner with gas, control knob 47 is rotated from the middle position in a clockwise direction as seen in FIG. 1 to the Gas position on cover plate 15. Under this condition of operation, cam surface 63 is displaced into engagement with plunger 81 of switch 73 to open same thereby deenergizing solenoid 105 and closing valve 107 in the gas conduit 109. At this time, switch 73 is closed and solenoid 115 is energized whereby valve 117 inoil conduit 119 is open to permit passage of oil to the burner. With rotation of control knob 47 from the Both position to the Gas position shield 123 is displaced in a counter-clockwise direction about pivot pin 125 thereby exposing the largest sized orifice 139 to the sighting tube and the sensitive element. As will be understood, the gas flame has the lowest intensity of radiant energy and, consequently, a maximum amount of the radiant energy from the gas flame to sensitive element 27 is desired.

It will now be apparent, from the foregoing description, that the present invention provides a novel and effective arrangement whereby the selection of a fuel to a multiple fuel firing burner may be obtained simultaneous with the presentation of a proper optical filter, or sized orifice, cor responding to the fuel to be used, to the radiant energy sensitive element. The present invention, of course, also contemplates the use of other fuels than that described, and in addition, a greater or lesser number of fuels depending upon the capability of the burner with which the present arrangement is to be used. For example, if a larger number of fuels to be fired by a burner are to be used, a corresponding increase in fuel control switches and optical filters or orifices can be provided. The teachings of the present invention still are followed in such case as long as the proper optical filter or orifice is determined for the corresponding fuel and the number of the filters or orifices in the shutter means is increased accordingly, together with an increase in the positions of the fuel selector knob. It should be understood also that there will be instances when the flame radiant energy intensity of one fuel may be the same as another fuel to be used, or a combination of fuels, so that the same filter or same size orifice may be used but the same shall occupy another position on the shield. Thus, if ten fuels are to be used in the burner and five fuels have the same intensity of flame radiant energy, ten filters or orifices are required on the shield and ten positions of the selector control knob. However, there will be six different type filters or six different sized orifices. Furthermore, the present invention envisagm the use of means other than a manually operated fuel selector control knob inasmuch as operation of the switches and shutter means could be effected from a remote point by remote control means.

Although one embodiment of the invention has been illustrated and described in detail, it is to be expressly understood that the invention is not limited thereto. Various changes can be made in the design and arrangement of the parts without departing from the spirit and scope of the invention as the same will now be understood by those skilled in the art.

What is claimed is:

1. In a multi-fuel selector and flame-failure safety control arrangement for use with a burner firing different combustible fuels, means for accommodating a radiant energy sensitive element the activation of which is a function of the amount of radiant energy impressed thereon, second means cooperating with the first-mentioned means and adapted for effecting transmission of the radiant energy of the flame of a burner to the radiant energy sensitive element, said second means forming paths having light transmitting capacities respectively inversely proportional to the intensities of the radiant flame energies of the fuels to be used in the burner, and fuel selector means adapted to select fuels characterized by flames of different radiant energy intensities, said fuel selector means being operable to simultaneously select the fuel to be used by the burner and actuate the second means to provide the proper path of light transmitting capacity to the radiant energy sensitive element in accordance with the radiant flame energy of the selected fuel to be fired by the burner.

2. In a multi-fuel selector and flame-failure safety control arrangement for use with a burner firing different combustible fuels characterized by flames of different radiant energy intensities, means for accommodating a radiant energy sensitive element the activation of which is a function of the amount of radiant energy impressed thereon, means cooperating with the first-mentioned means and adapted for effecting transmission of the radiant energy of the flame of a burner to the radiant energy sensitive element, shutter means including means forming radiant energy passages of selective capacity, said radiant energy passages having light transmitting capacities respectively inversely proportional to the in tensities of the radiant energy of the fuels to be burned, said radiant energy passages being formed and arranged for registry with the radiant energy sensitive element and the second-mentioned means to modulate the amount of radiant energy received by the radiant energy sensitive element, and a fuel selector means adapted to select the fuels characterized by flames of different radiant energy intensities, said fuel selector means operable to simultaneously select the fuel to be used in the burner and operate the shutter means to present the radiant energy passage or" proper capacity according to the radiant flame intensity of the fuel selected in registry with radiant energy sensitive element.

3. In a multi-fuel selector and flame-failure safety control arrangement for use with a burner firing different combustible fuels characterized by flames of different radiant energy intensities, means for accommodating a radiant energy sensitive element the activation of which is a function of the amount of radiant energy impressed thereon, means cooperating with the first-mentioned means and adapted for effecting transmission of the radiant energy of the flame of a burner to the radiant energy sensitive element, a fuel selector member movable to a plurality of positions for selecting the fuels characterized by flames of different radiant energy intensities to be used in the burner, each of said positions corresponding to the fuel to be used, shutter means including means forming a plurality of radiant energy passages of selective capacity having light transmitting capacities respectively inversely proportional to the intensities of the radiant flame energies of the fuels to be used in the burner, each of said radiant energy passages being formed and arranged for registry with the radiant energy sensitive element and the second-mentioned means to modulate the amount of radiant energy received by the radiant energy sensitive element, said radiant energy passages being equal in number to the number of positions for said fuel selector member, whereby each position of the fuel selector member has a radiant energy passage corresponding thereto, and means operably connecting the fuel selector member and the shutter means to simultaneously provide for the selection of' a fuel to be burned and to present the radiant energy passage of proper capacity commensurate with a particular fuel selected into registry with the radiant energy sensitive element upon movement of the fuel selector member to each of its different positions.

4. In a multi-fuel selector and fiame-failure safety arrangement for use with a burner firing different combustible fuels characterized by flames of different radiant energy intensities, a housing, means carried by said housing for accommodating a radiant energy sensitive element the activation of which is a function of the amount of radiant energy impressed thereon, sighting means carried by said housing adapted to effect transmission of the radiant ener y of the flame of a burner to the radiant energy sensitive element, shutter means interposed between the first means and said sighting means, said shutter means including means forming a plurality of radiant energy passages of selective capacity having light transmitting capacities respectively inversely proportional to the intensity of the radiant flame energies of the fuels to be used in the burner, each of said radiant energy passages being formed and arranged for registry with the radiant energy sensitive element and the sighting means to modulate the amount of radiant energy received by the radiant energy sensitive element, and fuel selector means operably for selecting the fuels characterized by flames of different radiant energy intensities to be used in the burner, said fuel selector means being connected to simultaneously select a fuel to be burned and operate the shutter means to position the radiant energy passage of proper capacity commensurate with the fuel selected to be burned in registry with the radiant energy sensitive element.

5. The arrangement of claim 4 wherein the shutter means includes a movable piate provided with means forming a plurality of radiant energy passages of selective capacities.

6. In a multi-fuel selector and flame-failure safety control arrangement for use with a burner firing different combustible fuels characterized by flames of different radiant energy intensities, means for accommodating a radiant energy sensitive element the activation of which is a function of the amount of radiant energy impressed thereon, sighting means cooperating with the first-mentioned means and adapted for effecting transmission of the radiant energy of the flame of a burner to the radiant energy sensitive element, shutter means interposed between the first-mentioned means and the sighting means, said shutter means including a movable plate having a plurality of radiant energy passages of selective capacity,

said radiant energy passages having light transmitting capacities respectively inversely proportional to the intensities of the radiant flame energies of the fuels to be burned, each of said radiant energy passages being formed and arranged for registry With the radiant energy sensitive element and the sighting means to modulate the amount of radiant energy received by said sensitive element, a fuel selector member movable to a plurality of positions for selecting the fuels characterized by flames of different radiant energy intensities, said plurality of positions being equal in number to the number of radiant energy passages carried by the movable plate, each of said positions corresponding to a fuel to be used having a particular flame radiant energy intensity and having a radiant energy passage corresponding to said position, and means interconnecting the fuel selector member and the movable plate to present the proper radiant energy passage corresponding to the radiant flame intensity of the fuel to be burned into registry with the radiant energy sensitive element upon movement of the fuel selector' member to its different positions.

7. The arrangement set forth in claim 6 which includes an electrical switch connected for operation by the fuel selector member, said switch being adapted for connection to energize mean controlling flow of different fuels to the burner.

8. The arrangement set forth in claim 6 wherein the movement of the fuel selector member is rotary in motion and the plate is pivotal, and spring means are provided for positively maintaining the filters in the plate member in registry with the radiant energy sensitive element.

9. In a multi-fuel selector and flame-failure safety control arrangement for use with a burner firing different combustible fuels characterized by flames of different radiant energy intensities, a housing, means carried by said housing for accommodating a radiant energy sensitive element the activation of which is a function of the amount of radiant energy impressed thereon, sighting means carried between the housing and adapted to effect transmission of the radiant energy of a burner flame to the radiant energy sensitive element, shutter means in the housing interposed between the first-mentioned and the sighting means and including a pivotal plate having a plurality of orifices, said orifices having light transmitting capacitie respectively inversely proportional to the intensities of the radiant flame energies of the fuels to be burned, each of said orifices being formed and arranged for registry with the radiant energy sensitive element and the sighting means to modulate the amount of radiant energy received by the radiant energy sensitive element, a fuel selector member rotatable to a plurality of positions for selecting fuels characterized by flames of different radiant energy intensities, said positions being equal in number to the number of orifices in the movable pivotal plate, each of said positions corresponding to a fuel to be burned having a particular radiant flame intensity and having an orifice corresponding to each position, means interconnecting the fuel selector member and the plate for pivoting the latter upon rotation of the fuel selector member to its different positions to present the proper orifice corresponding to the radiant flame intensity of the fuel selected into register with the radiant energy sensitive element, and an electrical switch in said housing operable by the fuel selector member, said switch being adapted for connection to orifice means controlling flow of different fuels to the burner.

10. The arrangement of claim 9 wherein spring means are provided in the housing and in engagement with the pivotal plate for positively maintaining the orifices in the plate in registry with the radiant energy sensitive element.

11. The arrangement of claim 9 wherein the shutter means also includes a stationary plate having an orifice in permanent registry with the radiant energy sensitive element and corresponding to one position of said fuel selector member, the orifice in the stationary plate being effective upon displacement of the pivotal plate at least partially out of the line of sight of the radiant energy sensitive element with the flame area of the burner.

12. In a multi-fuel selector and flame-failure safety control arrangement for use with a burner firing different combustible fuels characterized by flames of different radiant energy intensities, a housing, a sighting tube carried by and extending into the housing and adapted to sight the flame area of the burner, a second tube carried by the housing and disposed in alignment with the sighting tube, said second tube being constructed for supporting therein a radiant energy sensitive element the activation of which is a function of the amount of the radiant energy impressed thereon, shutter means in said housing interposed between the sighting tube and the secand tube and operable for modulating the radiant energy to the radiant energy sensitive element from the burner flame area, said shutter means including a pivotal plate and a stationary plate each having at least one orifice therein of different size and dimensioned to form paths having light transmitting capacities respectively inversely proportional to the intensity of the radiant flame energy of the fuels to be burned, said orifi :es being formed and arranged for registry with the radiant energy sensitive element to vary the amount of radiant energy to the latter, said stationary plate being disposed adjacent the sighting tube with the pivotal plate arranged between the stationary plate and the second tube, said pivotal plate further being displaceable away from said tubes to present a view of the orifice in the stationary plate to the burner flame area, a rotatable fuel selector member movable to a plurality of positions to select the fuels characterized by flames of different radiant energy intensities, said positions being equal in number to the number of orifices of the shutter means, each of said positions corresponding to a fuel to be used having a particular radiant flame intensity and having an orifice corresponding thereto, an electrical switch connected for operation by the fuel selector member, said switch adapted for connection to energize means controlling the flow of different fuels to the burner, and means interconnecting the fuel selector member and the pivotal plate to provide for selecting a fuel to be burned and simultaneously present the proper orifice into registry with the radiant energy sensitive element upon movement of the fuel selector member to its different positions.

13. The arrangement of claim 12 wherein the pivotal plate is pivoted at a point intermediate the ends thereof, one end of said pivotal plate containing the orifices and the other end being adjacent the fuel selector member, the fuel selector member further having a pin movable within a slot formed in said other end of the pivotal plate to effect movement thereof, and a spring cooperating with one end of such plate for positively maintaining the plate in positions displaced to by the fuel selector member.

References Cited in the file of this patent UNITED STATES PATENTS 1,959,654 Berg May 22, 1934 2,306,073 Metcalf Dec. 22, 1942 2,839,130 St. Clair June 17, 1958