US 3353583 A
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Nov. 21, 1967 F.J. SILHAVY E L INFRA RED RAY GENERATING SPACE HEATER 2 Sheets-Sheet 1 Filed Aug. 26. 1965 l/VVE/VfdfS F PA/VA J, S/Zl/AV) ROBERT 6/ OEBREY 21 I KIVA Nov. 21, 1967 F. J. SILHAVY ET AL INFRA RED RAY GENERATING SPACE HEATER 2 Sheets-Sheet 2 Filed Aug. 26, 1965 why W n $4 w M 7 W a United States Patent 3,353,583 INFRA RED RAY GENERATLNG SPACE HEATER Frank J. Silhavy and Robert J. Debrey, Oak Park, Ill.,
assignors, by mesne assignments, to Caloric Corporalion, Topton, Pa., a corporation of Pennsylvania Filed Aug. 26, 1965, Ser. No. 482,696 4 Claims. (Cl. 158-114) ABSTRACT OF THE DISCLOSURE A gas burning infra red ray generator comprising a narrow elongated casing; having an elongated bottom opening covered by a combustion sustaining screen; a venturi tube discharging at about the center of the casing; a horizontal perforated bafile below the venturi and above the screen; a vertical baffle registering with the lower portion of the venturi tube discharge opening to deflect the gas issuing therefrom toward said horizontal bafile; and a partition dividing the casing above said horizontal bafile into parallel, longitudinal compartments.
This invention relates to an infra red ray generator of the type Where gaseous fuel is burned on the surface of a screen to bring it to incandescence which is the optimum temperature for the generation of infra red rays.
One object of this invention is to produce an improved radiant burner of the type set forth.
A further object is to produce a space heater of a configuration which permits a number of heaters to be arranged in any desired pattern so as to provide uniform heat regardless of size or of the configuration of the area to be heated.
A still further object of this invention is to provide a space heater which is adapted for indoor and for outdoor use.
A still further object is to produce an improved space heater which is simple, easy to operate, and reliable.
These and other objects are attained by our invention which is set forth in the following specification and in the accompanying drawings in which:
FIG. 1 is a view, partly in section and partly in elevation, certain parts being partially broken away to show the internal construction, the view having been taken along line 11 on FIG. 2.
FIG. 2 is a sectional view looking in the direction of line 2-2 on FIG. 1.
FIG. 3 is an enlarged sectional view looking in the direction of line 33 on FIG. 2.
FIGS. 4, 5 and 6 are schematic examples of the improved radiation patterns produced by burners embodying the invention.
The gas-burning infra red ray generating heater illustrated consists of an elongated casing 10, having a relatively narrow bottom opening 12 which is covered by combustion sustaining screen assembly 14. Casing 10 is preferably formed of sheet metal, and comprises a top wall 16, side walls 18, and bottom walls 20, which converge downwardly and the edges of which define previously mentioned opening 12 which preferably extends the entire length of the casing. One end of the casing is closed by end wall 22 and the other by end wall 24 through which passes a venturi tube 26. Gas is delivered to the venturi tube by means of a suitable fitting, not shown, which is positioned in, or adjacent the outer, bell-shaped end 27 of the venturi tube.
The screen assembly 14 which overlies opening 12 is formed of two, or more, screens 23 and 29 which are closely spaced and an outer screen 30 which is spaced from screen 29. Screens 28 and 29 are prefer-ably about 40 mesh and are clamped in position as shown in FIG. 1, or otherwise.
As best shown in FIG. 1, venturi tube 26 extends into the casing and slopes upwardly in the direction of its inner end. The lower portion of the outlet of the venturi tube 26 registers with the inner, upwardly curved end 32 of an elongated baffle 34, the horizontal portion 26 of which extends substantially the entire length of the venturi tube, FIG. 1.
The horizontal portion 36 of the bafiie is provided with openings 38 which discharge gas downward toward opening 12. Openings 38 may also be provided, to the desired extent, in the curved end portion 32 of the bafile. The size, number, spacing and distribution of openings 38 may be varied with the length and width and depth of the burner. The approximate dimensions shown are satisfactory for a burner screen about 6' in length and approximately 2 to 3" in cross section. The baffie is preferably provided with a central partition 40 which divides the gas issuing out of the venturi tube into two streams and helps to support the venturi tube, FIG. 1. The outer end 42 of the baffle stops short of end wall 24 so as to provide an opening 44 for delivering gas quickly to pilot burner 46 as soon as the burner is turned on, thereby providing quick ignition without the necessity of waiting until the entire casing 10 has filled up. To protect pilot burner 46 from being extinguished by outside air currents, and from being smothered by the products of combustion, it is surrounded by an open, box-like structure 45, FIG. 1. Likewise, outer screen 30 stops short of end wall 24 to allow the installation of pilot burner 46 immediately below opening 44 and below the adjacent ends of screens 28 and 29, FIG. 1. It will be noted that the upper portion of the inner, discharge end of the venturi tube clears the baffle 34 and that the gas-air mixture issuing from the venturi tube will follow the paths indicated by arrows A, B, and C. Laboratory tests conducted with a prototype having an opening 12 of about 3" x 72" showed that, immediately upon turning the gas on, ignition begins at pilot 46 and progresses rapidly and smoothy toward the distal end of the burner and that extinguishment, due to turning the gas ofi, proceeds in the reverse direction. It will be understood that the fuel is burned over the outer surface of outer combustion screen 29 and that inner screen 28 serves to prevent backfiash. Outer screen 30 is preferably of about #16 mesh and serves to re-radiate the energy derived from the combustion of fuel. Screen 30 also serves to moderate air currents and makes the burner particularly adapted for outdoor use, and in large, drafty enclosures such as arenas, warehouses, and so on. Screen 30, being relatively rigid, also protects fine mesh screens 28 and 29 against accidental damage.
Screens 28, 29 and 30 are arcuate in cross section so as to enlarge their effective surfaces and any, or all, of them, may be undulated as shown in Patent No. 3,122,197, and for the same purpose. The upward curvature of the surface of the screens expedites the rem-oval of the products of combustion from the screen surfaces to provide for clean burning of uncontaminated gas with no risk of the flames on the screen surfaces being dimmed or smothered. Communicating with both edges of screen 30 are vertical flues which have bottom openings 58 and upper exhaust openings 62. The total exhaust port area is designed large enough to prevent the accumulation of a layer of burned gases on the surfaces of screen 30. The convection which develops in fines 60 serves to draw off products of combustion to eliminate any smothering of the burner flames on screen 30 and also prevents any recirculation of combustion products into the inlet bell 23 of the venturi tube 26.
Additionally, the burner casing 10 is provided with cooling chambers 2 running the entire length of the side walls 18. Cooling chambers 52 are sealed at the bottom and are provided with exhaust openings 54 at the top. Cooling chambers 52 prevent heat transfer between products of combustion in fiues 6t and the interior of casing 10, thus keeping the interior of the casing at a temperature below the flash point of the fuel mixture in the casing. To further insure rapid removal of the products of combustion from screen 3! we provide pendant side wings 56 which coact with the adjacent surfaces of screen 30 to form funnels leading to the openings 53 in the bottoms of fiues 69. Additionally, side wings 56 are constructed of a bright finish which will act as a reflector to direct downwardly the infra red emission from the curved surfaces of screen 30. Bottom openings 58 of fiues 69 also provide for release of atmospheric disturbances directed at the surface of screen 33 to further protect the combustion chamber against drafts and gusts of wind, thus further adapting the burner for outdoor use. But, openings 58 must not be large enough to permit movement of air in such quantities or at such rate as to cool screen 30.
The heater of the present invention relies, for its effect, on infra red rays which, like light rays, travel in straight lines. This means that a planar, square radiating surface will emit rays in a square pattern which will cover a planar square area, which at a very close range, such as one foot or so, will be almost equal to the area of the emitting surface. The same holds true for all planar geometrical configurations. But, as the distances from the emitting to the target surface increases, the area of the pattern on the target surface also increases. Partly to insure effective heating of the target area and partly because modern ceilings are relatively low, overhead installations, in inhabited quarters, will be from about eight to about ten feet from the target area which, for the purposes of this disclosure, will be the floor. It is to be understood, however, that a heater embodying this invention can be mounted to irradiate a ceiling, or a vertical wall, or other target area or object.
When the target area is such that it can be covered by a single burner of the same shape, the target area will be acceptabley heated. But, scientifically controlled tests showed that, when the target is of an irregular shape, or when two or more burners are needed to cover the target area, acceptable heating can not be achieved by round, or square planar heaters because, if the radiation patterns of adjacent heaters overlap, intermediate hot spots are produced and, if the radiation patterns are spaced apart, cold spots will result. For example, if a 2 x 5' heater is used to heat a 3 x 5 area, it will leave cold marginal areas. If two 2' x 5' heaters are used, their radiation patterns will overlap and will create a hot spot. In other words, for uniform heating, one must custom-tailor each heater, or one must carry a prohibitive variety of shapes and sizes in stock.
This difficulty is exemplified in FIG. 4, the area of which is assumed to be 2 x 6. A single burner 2' x 6 will be too heavy and the screens may warp, and it will not be usable in smaller locations. If it is assumed that heaters of 2' X 2' are practical and if three burners are mounted at a distance of 8' away, their radiation patterns will overlap to produce hot spots at the areas designated by arrows 64. If only two heaters are used, the gaps between the radiation patterns will produce cold spots. If the target area is irregular, or if it is of a value which is not a multiple of the emitting area of burner, the difficulty is multiplied.
The problems posed by way of example, and other similar problems are solved in the manner diagrammatically shown in FIG. 5, the area of which is also assumed to be 2' x 6', or the same as that of FIG. 4. According to this invention, four heaters of 3 x 72" are mounted, at a distance of 8, so that their radiating patterns meet along lines 66 with imperceptible overlap, or gap between, the radiation patterns emitted by adjacent heaters. It will be noted that the heaters can be arranged to extend in a direction at an angle to lines 66.
The versatility of the burner of this invention is further illustrated in FIG. 6 which shows an area of irregular shape and how it can be adequately covered by the radiation patterns of narrow burners 3 wide and of uniform, or different lengths.
To carry out this invention, the burner can be massproduced in standard 2" and 3" witdths and 24", 48", or 72" lengths. Out of this stock of ready-made burners, the desired number, of the desired length and width, are selected and arranged in the desired pattern. Since the width of the target area irradiated at any given distance from the emitting surface is known, it is'a simple matter to so space the burners that the longitudinal edges of the irradiation patterns will meet with imperceptible overlap or with imperceptible separation. This is true only as long as the width of the burner is small enough so that one heater will suffice for the narrowest conceivable area to be heated and so the multiple burners can be used to cover multiples of the area referred to.
In addition to the versatility above noted, the internal structure of the heater makes for uniform ignition over a relatively long combustion surface and permits use of the burner outdoors, or where the ambient air is not as still as it is in ordinary, inhabited enclosures.
It will be noted that when fiues 60 and wings 56 are heated they also act as emitters of long wave heat rays which supplement the heat radiated by the screens and, to that extent, raise the efiiciency of the unit. Additionally, side wings 56 can be coated with iron oxide, or ground coat porcelain or other emissive material, so as to serve as radiating as well as reflecting surfaces.
The side openings 62 of fiues 60 to prevent rain from reaching the screens and minimize downdrafts which can occur if openings 62 were in the top walls of the fiues and which may discourage the rise of the products of combustion. This is particularly true when the burner is first lit and the upward draft in fiues 60 is weak, downdrafts can discourage the movement of the products of combustion away from the surface of screen 30.
Both the diameter of throat 75 and the diameter of outlet 76 of the venturi tube affect operation. Too small a throat limits the entrance of primary air with resulting poor combustion. Conversely, too large a throat permits excessive primary air which acts to cool the burner screen. An excessively large outlet 76 acts to raise the high gas-air flow under cold conditions and creates ignition problems. The length of the portion 77 of the venturi tube also must be in proper relationship to the overall length of the burner screens. Testing has shown that in a 72' long burner the diameter of throat 75 should be about 2"; the diameter of outlet 76 should be about 273"; and the length of portion 77 of the venturi tube should be about 12''.
The flow of gas which is needed under hot operating conditions, is excessive under cold, non-operating conditions and interfered with initial lighting, or ignition of the burner. Under hot operating conditions, a stack action develops in the venturi tube which acts in the reverse direction and interferes with the fiow of gas out of the venturi tube outlet 76. To overcome this difiiculty, the inner end 32 of the baffle is arranged to align with a portion of the area of the venturi tube outlet so as to retard the outward flow of gas under cold conditions and so as to neutralize the momentum of gas flow toward the venturi tube outlet 76. In other words, the end 32 of bafile which is juxtaposed with the venturi outlet serves as a moderator, or modulator of the gas flow under both hot and cold conditions.
The baffle is of equal importance in its ability to balance the fiow of gas to all parts of the combustion screen so as to obtain prompt ignition and so as to insure uniform combustion.
Placing pilot 46 as shown takes it out of the range of flow of the products of combustion, which could weaken or extinguish it, and insures a supply of ambient air sufiicient to keep the pilot lit.
What we claim is:
1. An infra red ray generator comprising an elongated casing having a bottom opening substantially coextensive therewith,
an arcuate, combustion sustaining screen covering said opening,
a pair of vertical flues disposed exteriorly of said casing and extending substantially the length of the casing and having bottom openings adjacent the respective edges of said screen to draw products of combustion ofi said screen, and
a pair of shields depending from opposite sides of said flues and spaced from, and substantially coextensive with, said screen to protect said screen from horizontal air currents,
said shields coacting with said flues to accelerate the flow of the products of combustion oif said screen and up through said fiues for discharge through exhaust openings in the upper portion of said flues.
2. An infra red ray generator including:
an elongated casing having a bottom opening substantially coextensive therewith,
a gas combustion sustaining screen covering said opening,
a venturi type air-gas mixing tube extending longitudinally of said casing and said bottom opening having its intake end near one end of said casing and its discharge end near the center of the casing,
a horizontal, perforated bathe disposed between said tube and said bottom opening and coextensive with the length of said venturi tube and coextensive with the width of the casing, and
an upwardly curved bafiie coextensive with the width of the casing, carried by the inner end of said horizontal baflle and overlying the lower portion of the discharge end of the venturi tube, to deflect some of the gas flowing through said venturi tube toward the perforations in said baffle,
the remaining portion of the discharge end of the Venturi tube being unobstructed to permit the gas to move freely toward the other end of the casing.
3. The generator of claim 2 wherein the axis of said venturi tube and the plane of said horizontal bafile diverge in the direction of said other end of said casing.
4. The generator of claim 2 and a vertical partition rising from said horizontal bafiie toward the underside of the venturi tube and dividing the portion of the casing above said horizontal baffle into parallel longitudinal compartments.
References Cited UNITED STATES PATENTS 1,977,947 10/ 1934 Luten'oacher.
2,130,086 9/1938 Hart 12692 3,028,909 4/1962 Faure 1581 14 X 3,169,572 2/1965 Constance et al. 158-116 3,173,412 3/1965 Wright 12692 3,185,204 5/1965 Loeb et a1. 158114 3,219,097 11/1965 Prince et a1. 158-114 3,291,187 12/1966 Haensel 158-116 FOREIGN PATENTS 893,101 4/1962 Great Britain.
FREDERICK L. MATTESON, JR., Primary Examiner. R. A. DUA, Assistant Examiner.