US3331424A

US3331424A - Universal gas burner for heating equipment

Info

Publication number: US3331424A
Application number: US484362A
Authority: US
Inventors: Heinrich Rudolf
Original assignee: Haller Meurer Werke AG
Current assignee: Haller Meurer Werke AG
Priority date: 1964-09-03
Filing date: 1965-09-01
Publication date: 1967-07-18
Anticipated expiration: 1984-07-18
Also published as: LU47449A1; AT255698B; CH419022A; BE656110A; NL6415269A; GB1029726A

Description

July 18, 1967 R. HEINRICH 3,333,424

UNIVERSAL GAS BURNER FOR HEATING EQUIPMENT Filed Sept. 1, 1965 2 Sheets-Sheet 1 Iii-Til 'IiI'TIIIii lnvenfor: I R a 5 H6101 rick July 18, 197 R. HEINRICH 3,331,424

UNIVERSAL GAS BURNER FUR HEATING EQUIPMENT Filed Sept. 1, 1965 2 Sheets-Sheet lnvemor: IQZLLZL' Hi 171764 Ii [1 w United States Patent 3,331,424 UNIVERSAL GAS BURNER FOR HEATING EQUIPMENT Rudolf Heinrich, Hamburg-Bahrenfeld, Germany,

assignor to Haller-Meurer-Werke A.G., Hamburg- Altona, Germany Filed Sept. 1, 1965, Ser. No. 484,362 Claims priority, application Germany, Sept. 3, 1964, H 53,698 8 Claims. (Cl. 158117) ABSTRACT OF THE DISCLOSURE A universal gas burner for gas heating equipment mainly comprising a gas nozzle having an outlet end, passage means communicating With the nozzle at a location spaced from the outlet end for feeding gas into the nozzle, a mixing tube having an inlet end substantially aligned with the outlet end of the nozzle, combustion air inlet means communicating with the inlet end of the mixing tube, a burner tube communicating with the end of the mixing tube opposite the inlet end thereof and :being formed with a plurality of openings, and control means cooperating with the nozzle, the combustion air inlet means and the openings for controlling the flow of a mixture of gas and air through the openings, one dependent upon the other.

The present invention relates to a universal gas burner for gas heating equipment. Such gas burners usually include a gas nozzle, an inlet for the combustion air, a mixing tube, and a burner tube provided with openings, or slots.

Such known universal gas burners have, however, the disadvantage that, when changing over to a different type of gas, it is necessary not only to change the gas nozzle and to vary the flow cross section for the combustion air, but usually it is also necessary to provide another burner tube, with openings or slots which are adapted to the ignition speed of the particular type of gas used.

Apart from the fact that the time consumed for exchange of the various components of the gas burner is quite considerable, these operations can usually be carried out only by a skilled mechanic.

It is one object of the present invention to provide a universal gas burner which can be adapted for use with a particular type of gas in an expedient manner and without requiring any tools or particular skill.

It is a further object of the present invention to provide a universal gas burner of the aforementioned type which can be quickly adapted for use of different types of gas and which can also be adjusted according to the desired heating effect to be produced by the gas burner.

It is an additional object of the present invention to provide for a universal gas burner of the above-mentioned type which is composed of few and relatively simple parts so that the gas burner can be manufactured at reasonable cost and will stand up trouble free under extended use.

With these objects in view, the universal gas burner according to the present invention mainly comprises a gas nozzle having an outlet end, passage means communicating with the nozzle at a location spaced from the outlet end thereof for feeding gas into the nozzle, a mixing tube having an inlet end substantially aligned with the outlet end of the nozzle, combustion air inlet means communicating with the inlet end of the mixing tube, a burner tube communicating with the end of the mixing tube which is opposite the inlet end thereof and which is formed with a plurality of openings, and control means cooperating with the nozzle, the combustion air inlet 3,331,424 Patented July 18, 1967 means and openings in the burner inlet for controlling the flow of gas and combustion air into the mixing tube and the outflow of the mixture of gas and air through the openings, one dependent upon the other.

The control means preferably include a manually opera ble control member for adjusting the flow of gas through the outlet end of the nozzle depending on the type of gas used for the burner and for simultaneously and correspondingly also controlling the flow of combustion air into the mixing tube.

In a preferred embodiment of the invention provision is made that the gas nozzle and the fresh air intake for the burner, as well as the openings in the burner tube are each associated with a shutter or diaphragm. The operation of the hand-control provides for a direct adjustment of the shutter or diaphragm for the gas nozzle and additionally for the corresponding adjustment of combustion air feed.

The shutter or control for the gas nozzle is preferably in the form of a rotary member and the latter is formed preferably in one piece with a shutter for the combustion air feed, for which purpose the rotary member is in the form of a cupshaped member. This cup-shaped member is provided with openings of different size and ar ranged so that upon operation of the manual control the openings appropriate to the particular type of gas selected come into working position.

The afore-mentioned shutter or control for varying the outflow cross section of the burner tube is also indirectly operated from the aforementioned manual control in that after operation and starting of the gas burner equipment the heat produced according to the adjustment of the aforementioned shutter controlling the flow of gas and combustion air into the mixing tube will influence a thermostat or thermally responsive device which adjusts, through a regulator the shutters arranged in the burner tube and thereby the outflow of a mixture of gas and combustion air from the latter.

Preferably, the aforementioned regulator cooperates with a double-armed lever, one arm of which cooperates with a spring loaded nozzle needle for the nozzle and the other arm of which acts through an adjusting rod on the shutter in the burner tube.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

FIG. 1 is a partially sectioned side view of a universal gas burner according to the present invention;

FIG. 2 is a cross section taken along the line 11-11 of FIG. 1;

FIG. 3 is a partial, partially sectioned view of a burner tube and showing a modified control arrangement for controlling the outflow through the openings of the burner tube; and

FIGS. 4 and 5 are partial views showing different control arrangements.

Referring now to the drawings, and more particularly to FIG. 1 of the same, it will be seen that the universal gas burner according to the present invention includes a gas nozzle 2 with which passage means in form of a tube 1 communicate at a location spaced from the outlet end of the nozzle for feeding gas into the latter. The nozzle 2 together with pipe 1 are supported in a casing 4 formed with an opening 5 through which combustion air may pass into the casing 4. The casing 4 serves also to support shutter means 6, 7 in form of a cup-shaped 3 member for rotation about its axis. As can be seen from FIG. 1, the casing 4 is provided with cylinder portion in which the cup-shaped

rotary member

6, 7 is housed with the peripheral wall 7 of the cup-shaped rotary member engaging the peripheral wall of the cylindrical portion of the housing. The end wall 6 of the rotary member facing the corresponding wall of the cylindrical portion of the housing in front of the outlet end of the nozzle 2 is formed with a plurality of apertures 18 therethrough having respectively different size and being arranged spaced from each other along a circle coaxial with the turning axis of the rotary member and having a radius equal to the distance between the axis of the nozzle and the axis of the rotary member. The peripheral wall 7 of the rotary member is likewise formed with a plurality of apertures 19 therethrough which have respectively different size, and which are spaced from each other according to the spacing of the apertures 18.

A shaft 9 connected to the end wall 6 of the rotary member, and mounted for rotation about its axis in the manner as shown in FIG. 2, is provided at its outer end extending beyond the casing 4 with a knob 8 so that by turning the knob 8 the rotary member may be turned about its axis to align an aperture 18 of selected size with an opening in the wall of the cylindrical portion of the housing located in front of the outlet end of the nozzle 2 and to align at the same time a corresponding aperture 19 with an opening 20' formed in the peripheral wall of the cylindrical housing portion so that gas according to the selected aperture 18 may flow into the interior of the rotary cup-shaped member, while simultaneously combustion air may flow through the opening 5, the opening 20 and the selected aperture 19 into the interior of the rotary member.

A mixing tube 11 extends with an end portion thereof in the

rotary member

6, 7 in such a manner that the inlet end of the mixing tube 11 is aligned with and spaced from the outlet end of the nozzle 2, so that gas emanating from the outlet end of the nozzle will pass into the inlet end of the mixing tube 11 and thereby suck combustion air through openings and 20 and through the aperture 19 aligned with the opening 20 into the mixing tube 11. The mixing tube 11 may be supported in a manner not shown in the drawing and the portion extending into the rotary member supports a plate, as shown in FIG. 2, which closes the open end of the cup-

shaped member

6, 7 and which carries also a bearing for the shaft 9. Additional bafiles may be provided, not shown in the drawing, to prevent any gas emanating from the outlet end of the nozzle 2 to pass through aperture 19 and opening 20 into the interior of the housing 4 and from there through the opening 5 to the atmosphere. A burner tube 10 in integrally formed or fixedly and gas-tightly connected to the end of the mixing tube 11 which is opposite the inlet end thereof, and the burner tube 10 may, as shown in FIG. 1, extend at right angle to the mixing tube 11. The burner tube 10- is provided in known manner with openings 12 which are preferably of slot-like form and the open cross section of which can be varied according to the ignition speed of the particular type of gas used. For this purpose a shutter 21 is provided within the burner tube 1%), as shown in FIGS. 1 and 2, and the shutter 21 shown in these two figures is constructed as a rotary member and mounted on a shaft 22 which is arranged coaxial with the axis of the burner tube 10 and mounted therein in the manner as shown for rotation about its axis.

Rotation of the shaft 22 is produced by a pinion 28 fixed to the upper end of the shaft 22 and meshing with a rack 29 fixed to one end of a rod 17 mounted for reciprocation in longitudinal direction in two bearings as shown in FIG. 1. The other end of the rod 17 is connected to one end of one arm of a double armed lever 16 which is pivotally mounted intermediate its ends.

in FIG. 1

4 The end of the other arm of the double armed leved 16 engages a spring loaded needle valve member 3 located in the nozzle 2 movable toward and away from the outlet end thereof so as to control the flow of gas through V the outlet end of the nozzle. The lever 16 may be turned about its pivot axis, as shown in FIG. 1, by means of a temperature regulating device or moving means 13 which in turn is controlled by temperature sensing means in the nature of a thermostat 14. The device 13 is connected to one end of the rod 15, the other end of which is connected to the double armed lever adjacent pivot axis.

The specific construction of the temperature sensing means and of the device 13 does not form part of the present invention and any well known temperature sensing means and moving means 13 connected thereto may be used which will cause during variation of the temperature sensed by the temperature sensing means 14 movement of the rod 15 connected to the moving means 13 in one or the other direction.

The operation of the lever 16 is effected dependent on the adjustment of the shutter means 6, 7 operated by means of the manual control 8 and proceeds in such a manner that for instance an adjustment of the

shutter

6, 7 for one kind of gas with a higher heating value operates the device 13, after the heating equipment has been brought into operation, through the lever 16 in such a manner that the flow section of the openings 12 in the burner tube It) is reduced by reason of the shutter 21 and at the same time by shifting the spring loaded needle valve member 3 relative to the outlet end of the nozzle 2 to thus reduce the. gas flow through the nozzle.

It is also possible to effect common operation of the shutter 21 and the needle valve 3 by manually operable moving means and such an arrangement is shown in FIG. 4. As shown in FIG. 4, the manually operable moving means includes a disc 23 turnably mounted about its axis on an appropriate support, a gear ring 24 coaxially fixed in any suitable manner, not shown in FIG. 4, to the disc for rotation therewith, a pinion 25 meshing with the gear ring 24 and provided with a hub formed with a screw thread which engages a corresponding thread 26 on the rod 15, which, in turn is connected to one arm of the double-armed lever 16. Turning of the disc 23 about its axis in one or the other direction will be transmitted to the gear ring 24 and to the pinion 25 to result in axial displacement of the rod 15 in the one or the other direction to thereby adjust the position of the needle valve member 3 and the position of the shutter 21 in the burner tube 10. 0f course, the pinion 25 is held in a support, in a manner not shown in FIG. 4, against shifting in axial direction. The disc 23 is preferably provided with graduatons of the outer periphery thereof which cooperate with a stationary pointer on the support so that the position of the disc 23 can be easily ascertained.

Instead of providing manually operable means for shifting the rod 15 to adjust thereby the position of the needle valve 3 and the shutter 21, it is also possible to shift the rod 15 by means of a motor and such an arrangement is shown in FIG. 5. As shown in FIG. 5, an electromo-tor 27 drives a pinion 30 fixed to the motor shaft and the pinion 30 meshes with a gear 31 having a hub provided with an inner screw thread and meshing with a corresponding thread 26 on the rod 15. Operation of the motor 27 that is, starting, stopping, and reversing of the motor may be effected in a known manner from a thermostatic device, not shown in FiG. 5, or operation of the motor 27 may also be manually controlled by appropriate switches.

FIG. 3 shows a further modification .in which an axially movable shutter 28 is provided in the burner tube for varying the open cross section of the openings or slots 12 formed in the burner tube 10. The axially movable shutter 28 is provided with a plurality of spaced slots 31 corresponding in size substantially to the slots 12 in the burner tube and which are spaced from each other in axial direction according to the spacing of the slots 12. In this case, the rod 17 connected at one end thereof to the double-armed lever 16 as shown in FIG. 1, is connected at its other end to one arm of a belt crank 29, the other arm of which is connected in the manner as shown in FIG. 3, to the upper end of the rod 30, the lower end of which carries the shutter 28 fixedly connected thereto.

It will be seen that the universal gas burner according to the present invention can be adjusted not only in a very simple manner for a different sort of gas, but that also the regulating range of the burner is substantially increased so that practically any useful type of heating gas can be employed.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of universal gas burners differing from the type described above.

While the invention has been illustrated and described as embodied in universal gas burner, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various ap lications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. A universal gas burner for gas heating equipment comprising, in combination, a gas nozzle having an outlet end; passage means communicating with said nozzle at a location spaced from said outlet end for feeding gas into said nozzle; a mixing tube having an inlet end substantially aligned With said outlet end of said nozzle; combustion air inlet means communicating with said inlet end of said mixing tube; a burner tube communicating with the end of said mixing tube opposite said inlet end thereof and being formed with a plurality of openings; and control means cooperating with said nozzle, said combustion air inlet means, and said openings for controlling the flow of gas and combustion air into said mixing tube and the outflow of a mixture of gas and air through said openings, one dependent upon the other, said control means including three shutters respectively coordinated with said outlet end of said nozzle, said combustion air inlet means, and said openings of said burner tube, the shutters coordinated with said outlet end of said nozzle and with said combustion air inlet means being integral with each other and being formed by a cup-shaped rotary member having a front wall facing said outlet end of said nozzle and a peripheral wall facing said combustion air inlet means, said front wall and said peripheral wall being each formed with openings of different size respectively adapted to be aligned with said outlet end of said nozzle and said combustion air inlet means by turning said cupshaped rotary member about its axis.

2. A universal gas burner for gas heating equipment comprising, in combination, a gas nozzle having an outlet end; passage means communicating with said nozzle at a location spaced from said outlet end for feeding gas into said nozzle; a mixing tube having an inlet end substantially aligned with said outlet end of said nozzle; combustion air inlet means communicating with said inlet end of said mixing tube; a burner tube communicating with the end of said mixing tube opposite said inlet end thereof and being formed with a plurality of openings; first control means cooperating with said outlet end of said nozzle and with said combustion air inlet means for adjusting the flow of gas into said mixing tube and for simultaneously adjusting flow of combustion air into said mixing tube corresponding to the adjusted flow of gas thereinto; second control means cooperating with said nozzle and said openings of said burner tube for further controlling flow of gas from said nozzle into said mixing tube and for simultaneously and correspondingly adjusting outflow of a mixture of gas and combustion air through said openings of said burner tube, said second control means including a needle valve member located in said nozzle and being movable toward and away from said outlet end thereof for varying the free cross section of said outlet end, and shutter means in said burner tube movable relative to said openings for varying the free cross section thereof; temperature sensing means; and operating means cooperating with the temperature sensing means and operatively connected to said needle valve and said shutter means for moving said needle valve relative to said outlet opening of said nozzle and for simultaneously moving said shutter means relative to said openings of said burner tube.

3. A universal gas burner for gas heating equipment comprising, in combination, a gas nozzle having an outlet end; passage means communicating with said nozzle at a location spaced from said outlet end for feeding gas into said nozzle; a mixing tube having an inlet end substantially aligned with said outlet end of said nozzle; combustion air inlet means communicating with said inlet end of said mixing tube; a burner tube communicating with the end of said mixing tube opposite said inlet end thereof and being formed with a plurality of openings; first control means cooperating with said outlet end of said nozzle and with said combustion air inlet means for adjusting the flow of gas into said mixing tube and for simultaneously adjusting flow of combustion air into said mixing tube corresponding to the adjusted flow of gas thereinto; second control means cooperating with said nozzle and said openings of said burner tube for further controlling flow of gas from said nozzle into said mixing tube and for simultaneously and correspondingly adjusting outflow of a mixture of gas and combustion air through said openings of said burner tube, said second control means including a needle valve member located in said nozzle and being movable toward and away from said outlet end thereof for varying the free cross section of said outlet end, and shutter means in said burner tube movable relative to said openings for varying the free cross section thereof; temperature sensing means; and operating means including a double-armed lever pivotally mounted intermediate its ends, and having one arm operatively connected to said needle valve member and the other to said shutter means in said burner tube, and moving means cooperating with said temperature sensing means for turning said lever about its pivot axis depending on the temperature sensed by said temperature sensing means to thereby adjust the position of said needle valve member in said nozzle and the position of said shutter means relative to said openings in said burner tube dependent on the temperature sensed by said temperature sensing means.

4. A universal gas burner for gas heating equipment comprising, in combination, a gas nozzle having an outlet end; passage means communicating with said nozzle at a location spaced from said outlet end for feeding gas into said nozzle; a mixing tube having an inlet end substantially aligned with said outlet end of said nozzle; combustion air inlet means communicating with said inlet end of said mixing tube; a burner tube communicating with the end of said mixing tube opposite said inlet end thereof and being formed with a plurality of openings; first control means cooperating with said outlet end of said nozzle and with said combustion air inlet means for adjusting the flow of gas into said mixing tube and for simultaneously adjusting flow of combustion air into said mixing tube corresponding to the adjusted How of gas thereinto; second control means cooperating with said nozzle and said openings of said burner tube for further controlling flow of gas from said nozzle into said mixing tube and for simultaneously and correspondingly adjusting outflow of a mixture of gas and combustion air through said openings of said burner tube, said second control means including a needle valve member located in said nozzle and being movable toward and away from said outlet end thereof for varying the free cross section of said outlet end, and shutter means in said burner tube movable relative to said openings for varying the free cross section thereof; temperature sensing means; and operating means including a double-armed pivotally mounted intermediate its ends, and having one arm operatively connected to said needle valve member and the other to said shutter means in said burner tube, and manually operable moving means operatively connected to said lever for turning the latter about its pivot axis to thereby adjust the position of said needle valve member in said nozzle and the position of said shutter means relative to said openings in said burner tube.

5. A universal gas burner as set forth in claim 4, wherein said manually operable moving means include a disc turnable about an axis, a gear ring coaxially fixed to said disc, a pinion meshing with said gear ring and having a threaded hub, and a rod operatively connected at one end to one arm of said lever and having spaced from said one end a threaded portion threadingly engaging said hub of said pinion to be axially moved upon rotation of said pinion.

6. A universal gas burner for gas heating equipment comprising, in combination, a gas nozzle having an outlet end; passage means communicating with said nozzle at a location spaced from said outlet end for feeding gas into said nozzle; a mixing tube having an inlet end substantially aligned with said outlet end of said nozzle; combustion air inlet means communicating with said inlet end of said mixing tube; a burner tube communicating with the end of said mixing tube opposite said inlet end thereof and being formed with a plurality of openings; first control means cooperating with said outlet end of said nozzle and with said combustion air inlet means for adjusting the flow of gas into said mixing tube and for simultaneously adjusting fiow of combustion air into said mixing tube corresponding to the adjusted flow of gas thereinto; second control means cooperating with said nozzle and said openings of said burner tube for further controlling flow of gas from said nozzle into said mixing tube and for simultaneously and correspondingly adjusting outflow of a mixture of gas and combustion air through said openings of said burner tube, said second control means including a needle valve member located in said nozzle and being movable toward and away from said outlet end thereof for varying the free cross section of said outlet end, and shutter means in said burner tube movable relative to said openings for varying the free cross section thereof; temperature sensing means; and operating means including a double-armed pivotally mounted intermediate its ends, and having one arm operatively connected to said needle valve member and the other to said shutter means in said burner tube, and motor means operatively connected to said lever for turning the latter about its pivot axis to thereby adjust the position of said needle valve member in said nozzle and the posi- 7 tion of said shutter means relative to said openings in said burner tube.

7. A universal gas burner for gas heating equipment comprising, in combination, a gas nozzle having an outlet 7 end; gas passage means communicating with said nozzle at a location spaced from said outlet end for feeding gas through said second opening; a burner tube communicating with the end of said mixing tube opposite said inlet end thereof and being formed with a plurality of openings spaced from each other; a cup-shaped member in said casing and having an end wall abutting against said side Wall of said casing and a peripheral wall engaging with the outer surface thereof said annular wall of said casing, said cupshaped member being arranged in said casing turnably about a turning axis spaced from said outlet end of said nozzle and being formed in said end wall with a first plurality of apertures of different size arranged spaced from each other along a circle coaxial with said turning axis and in said peripheral wall with a second plurality of apertures of different size respectively spaced from each other according to the spacing of said first plurality of apertures; manually operable means connected to said cup-shaped member for turning the latter about said turning axis so as to align one aperture of selected size of said first plurality of apertures with said opening in said side wall of said casing and a corresponding aperture of said second plurality of apertures with said opening of said annular wall of said casing; a needle valve in said nozzle movable toward and away from said outlet end; shutter means in said burner tube and movable relative to said openings for adjusting the free cross section thereof; temperature sensing means; and operating means cooperating with said temperature sensing means and operatively connected to said needle valve and said shutter means for adjusting the position of said needle valve relative to said outlet opening of said nozzle and the position of said shutter means relative to said openings of said burner tube depending on the temperature sensed by said temperature sensing means.

8. A universal gas burner as set forth in claim 7, wherein said shutter means in said burner tube is a rotary member angularly adjustable about an axis coaxial with said burner tube, and wherein said operating means include a double-armed lever pivoted about a pivot axis intermediate its ends, a rod mounted for reciprocation in longitudinal direction and being operatively connected at one end thereof to one end of one arm of said lever and carrying on the other end thereof a rack, a pinion coaxial with and operatively connected to said rotary memher and meshing with said rack, moving means cooperating with said temperature sensing means and operatively con-.

nected to said lever adjacent said pivot axis for pivoting said lever about said axis depending on the temperature sensed by said temperature sensing means, and connecting means connecting the other end of said lever to said needle FREDERICK L. MATTESO-N, In, Primary Examiner.

H. B. RAMEY, Assistant Examiner.

Claims

1. A UNIVERSAL GAS BURNER FOR GAS HEATING EQUIPMENT COMPRISING, IN COMBINATION, A GAS NOZZLE HAVING AN OUTLET END; PASSAGE MEANS COMMUNICATING WITH SAID NOZZLE AT A LOCATION SPACED FROM SAID OUTLET END FOR FEEDING GAS INTO SAID NOZZLE; A MIXING TUBE HAVING AN INLET END SUBSTANTIALLY ALIGNED WITH SAID OUTLET END OF SAID NOZZLE; COMBUSTION AIR INLET MEANS COMMUNICATING WITH SAID INLET END OF SAID MIXING TUBE; A BURNER TUBE COMMUNICATING WITH THE END OF SAID MIXING TUBE OPPOSITE SAID INLET END THEREOF AND BEING FORMED WITH A PLURALITY OF OPENINGS; AND CONTROL MEANS COOPERATING WITH SAID NOZZLE, SAID COMBUSTION AIR INLET MEANS, AND SAID OPENINGS FOR CONTROLLING THE FLOW OF GAS AND COMBUSTION AIR INTO SAID MIXING TUBE AND THE OUTFLOW OF A MIXTURE OF GAS AND AIR THROUGH SAID OPENINGS, ONE DEPENDENT UPON THE OTHER, SAID CONTROL MEANS INCLUDING THREE SHUTTERS RESPECTIVELY COORDINATED WITH SAID OUTLET END OF SAID NOZZLE, SAID COMBUSTION AIR INLET MEANS, AND SAID OPENINGS OF SAID BURNER TUBE, THE SHUTTERS CO-