US2315809A - Hot-air furnace - Google Patents

Description

April 6, 1943.

R. MOYLE,

HOT-AIR FURNACE gFiled Aug. 4, 1940 I 2 jheets-Sheet -l April 6, 1943. R. MOYLE HOT-AIR FURNACE Filed Aug. 4, 1940 2 Sheets-Sheet 2 Patented Apr. e, 1943 UNl'iE STATES PATET OFFICE HOT-AIR FURNACE Application August 4, 1940, Serial NO. 351,424 2 Claims. (CL 126-99) This invention relates to certain new and useful improvements in hot-air furnaces.

My invention has for its primary object the provision of a furnace, which is economical in cost of construction, and which is composed of a relatively small number of readily replaceable parts, thus increasing the useful life of the furnace and simplifying its upkeep and maintenance.

My invention also has for additional objects the provision of a furnace of the type stated which uniquely embodies a chamber for the combustion of fuel with extremely high efiiciency and with the production of a minimum of smoke, fumes, and noxious gases, which enables highly efficient heat exchange for heating the air delivered by the furnace to the enclosures bein heated, and which may be readily and conveniently cleaned with a minimum of effort and without the necessity of removing or reducing the fire in the firebox.

My invention also has for a further object the provision of a furnace of the type stated having a crown sheet or head uniquely formed and constructed for eliminating turbulence of the air currents in the combustion-chamber, and which is further provided with unique over fire air tubes for effecting substantially complete combustion.

And with the above and other objects in View, my invention resides in the novel features of form, construction, arrangement, and combination of parts presently described and pointed out in the claims.

In the accompanying drawings (2 sheets),

Figure l is a vertical sectional view of a hotair furnace constructed in accordance with and embodying my invention;

' Figure 2 is a top plan view, partly broken away and in section, of the furnace;

Figure 3 is a front elevational view of the furnace, partly broken away and in section along the line 3-3, Figure 2; and

Figure 4 is a horizontal sectional view of the furnace taken approximately along the line 4-4, Figure 3.

Referring now in more detail and by reference characters vo the drawings, which illustrate a preferred embodiment of my invention, the furnace comprises an outer suitably insulated casing or shell A preferably of sheet steel and of rectangular cross-section, and which includes a front wall I, opposed parallel side walls 2, and a rear wall 3. The rear wall 3 is formed with a preferably centrally located exhaust outlet, as

24 preferably of triangular cross-section.

at t, for the products of combustion and with a second preferably rectangular aperture, as at 5, for the intake of air to be heated, the latter aperture being provided with an outwardly pro- ,ecting peripheral rim 6 preferably having its lower horizontal margin coincident with the bottom margin of the shell A.

The shell front wall I is provided with a central firing-door aperture I, a pair of obliquely disposed flue-door apertures 8, and an ash-door aperture 8, the apertures 8, 9, being respectively positioned above and below the door-aperture I and respectively located adjacent the upper and lower margins of the front wall I. all as best seen in Figures 1 and 3. I

Disposed or housed for the most part, as shown, within the shell or casing A and resting upon the floor or other foundation structure, is a so-called stove-member B, which includes a preferably cast-iron ash pit Iii preferably of rectilinear box-like formation having a flat bottom wall Ii, a rear wall I2, side walls I3, 21. top wall It, and front wall I5, the latter having a large rectangular aperture I6 for permitting access to the interior of the pit It).

On its upper or inner face, the bottom wall it is provided with a plurality of longitudinally extending channel-forming ribs It for slidably supporting a removable ash-pan p.

At its forward end, the pit la projects through the shell-aperture 9 and is provided with an outwardly extending peripheral flange I8 for securement to the outer face of the casing front wall i, and swingably mounted upon the front wall i5 adjacent one of the vertical margins of the aperture I6, is a conventional door I9 centrally provided with a draft window 19' having a swingable lid-like draft-door 20.

Formed preferably integrally with, and projecting downwardly from, the top wall It of the ash-pit I8, is a plurality of pairs of longitudinally aligned bosses 2 I, 22, and journaled therebetween are spaced parallel grate bars 23 having sections At their respective forward ends 25, the grate bars 23 are of conventional square cross-section and in registration with shaker apertures 26 formed in the door is and closed by conventional swingable cover-plates 21.

In its top wall I4, the ash-pit Iii is further pro vided with a rectangular opening or aperture 28 and upon its upper face with a continuous upstanding flange 2% spaced outwardly from the peripheral margin of the aperture 28 in the formation of a channel, as at c for snugly receiving the lower margin of a downwardly and outwardly tapering fire-pot or combustion chamber preferably of rectangular horizontal section and, in turn, provided adjacent its upper margin with an enlarged peripheral rim 3! cut away at its inner and upper face in the provision of a channel, as at c, for snugly seating the downwardly presented flange 32 of a firing-box or chamber 33 in full communication with the chamber 30 and projecting at its forward end through, and sized for snug-fitting engagement with, the shell-aperture l and having a front wall 34 centrally provided with a fuel-charging opening or aperture 35 and an upstanding peripheral flange 35 for securing engagement with the outer face of the casing-front wall I. Swingably mounted upon the front wall 34 adjacent one of the vertical margins of the charging aperture 35, is a conventional door 31.

Extending through and opening upon the outer faceof the front wall 34 on opposite sides of the door 37, are air inlet or draft tubes 38, which are preferably of elliptical cross-section, and which extend inwardly for substantially the entire length of the chamber 33, the tubes 38 being supported at their respective inner or closed ends in saddle blocks 39 formed preferably integrally with, and projecting forwardly from, the rear transverse wall 40 of the chamber 33. Over that portion of their length extending across the chamber 33 proper, the tubes 38 are provided with downwardly and inwardly presented slots 4| for admitting air directly across the bed of coals or other fuel for approximately the full depth of the chamber 33 in order to provide effi cient and substantially smokeless combustion. Swingably mounted upon the outer face of the chamber front-wall 34, are suitable preferably oval-shaped damper doors 42 for controlling the flow of air into the tubes 38 and from the tubes 38 through the openings 4| into the combustionchamber 30.

In its upper wall 43, the chamber 33 is provided with a draft or flue-opening, as at 44, rimmed by an upstanding wall or flange 45 and along its rear and side margins provided with a laterally projecting flange 45. Fitted snugly around the flange 45 and having a laterally flaring marginal flange 41 seated upon and, as shown, secured to the wall 43 and flange 46, is substantially a discharge-chamber Y, which has an obliquely upwardly and forwardly presented somewhat arcuate or peaked top or crown sheet 48 and preferably integral straight vertical side walls 49, and a rear wall 50. I Secured at its lower margin by means of a suitable flange 52 to the upper face of the chamber 33 and across the open-front of the crown sheet 48, is a flue-apron 53 suitably joined along its upper margin to an upwardly and forwardly projecting oblique wall 54 extending equidistantly on opposite sides of the apron 53 substantially across the entire width of the housing A and, in turn, joined to a vertical front wall 55 suitably apertured for accommodating frames 56 having the shape of oblique parallelehedrons and positioned in relation to each other somewhat in the formation of a hollow inverted V and extending snugly through the flue-door openings 8 of the casing front wall I to swingably support on their opposed vertical margins suitably shaped cleanout doors 51, all as best seen in Figures 1 and 8 and for purposes presently fully appearing.

Welded or otherwise suitably fixed along its forward margin to the front wall 55, is a rear wardly extending annular wall 58 conforming generally to the peripheral shape of the front wall 55 and likewise welded at its rearward margin to the upper margin of a vertical tube-sheet 59, which is, in turn, secured at its lower margin to the forward margins of the crown-sheet top wall Si in the formation of an enclosed tubedrum or header d. Mounted at their forward ends in the tube sheet 59 for communication with the tube drum (1 and preferably positioned in directly juxtaposed relation to th clean-out doors 51, is a plurality of rearwardly extending horizontal tubes 60, whichare, in turn, at their rear end mounted in the forward wall 6| of a socalled clean-out or dust box 6 extending vertically downwardly a substantial distance below the rear wall aperture 4 and having a rearwardly spaced vertical back wall 62 connected to the front wall 6| by an upturned arcuate bottom wall 63, vertical side walls 64, and a transverse top wall 65. Mounted in the back wall 62 for communication with the dust box e and projecting snugly through the rear wall aperture 4 of the casing A, is a flue-connection pipe 66 for receiving a conventional flue-pipe or stack-connection (not shown). Likewise mounted in one of the side walls 64 for communication with the lower portion of the dust box 6, is a clean-out tube 61 projecting horizontally through the adjacent casing side wall 2 and at its outer end provided with a conventional swinging trap-door 68, all as best seen in Figure 3.

In use, the fuel ischarged into the door 31 and the intensity of the blaze regulated by opening and closing the damper-door 20. The fire is further controlled by opening and closing the air-tube doors 42 to admit more or less air to and over the burning fuel. The air from the rooms or enclosures being heated is drawn either by normal or forced draft, as desired, through the rear wall opening 4 and circulated within the casing A, as shown in Figure 1, around the outer surfaces of the fire-pot 30, chamber or fire-box 33, chamber Y, flue- apron walls 53, 54, tubes 60, and thence through the conventional distribution header (not shown) to household distribution pipes.

The rectangular shape of the fire-pot 2a and its associated parts enables proper alternate firing without disturbing the coal bed on the side previously fired and the sloping or tapered character or formation of the fire-pot 3i! proper permits the ashes and solid residue to fall away from the pot sides, giving direct contact for heat transfer from the burning coals to the metal. Adequate space is also thus provided for expansion of the coal as combustion proceeds, thus preventing logging of the grate.

The introduction of air directly over the fire results in complete, efficient, and smokeless combustion, and the sloping contour of the crownsheet guides the flue gases to the tube-drum without causing turbulence of the air currents in the combustion chamber and similarly the heated air is directed smoothly and without burbling over the outer faces of the tube-drum and tubes 66.

The arrangement of the tubes 60, clean-out doors 51, dust box 6, and soot clean-out 6! permit convenient cleansing of th entire length of the tubes 50 and other flue surfaces, and the travel of the products of combustion through the several tubes 60 serves to more or less rapidly and effectively, in the nature of a radiator, heat the air within the shell A.

Finally, the hollow grate bar-shaft sections 24 prevent warping of the bars 23 due to overheating, and the cast-iron structure of the pit l0 and firebox 33 economically enable efficient long-life without repair or replacement. The furnace in every respect fulfills the objects stated, and it should be understood that changes and modifications in the form, construction, arrangement, and combination of the several parts of the furnace may be made and substituted for those herein shown and described without departing from the nature and principle of my invention.

Having thus described my invention, what I claim and desire to secure by Letters Patent is,

1. A hot-air furnace Comprising an upright outer casing of substantially rectangular cross section having an air intake opening through its wall low down and a heated air outlet at its top, said casing having its front wall provided with a firing-door aperture and an ash-door aperture, stove structure disposed in the middle of and spaced from the walls of said casing comprising a substantailly rectangular ash-pit having an ash removal opening extension registering with the ash-door aperture and a substantially rectangular fire-pot mounted upon the ash-pit and having the inner face of its wall downwardly and outwardly tapered and a substantially rectangular fire-box mounted upon the fire-pot provided with a flue opening at its top and having a fuel-charging opening extension registering with the firedocr aperture, a flue header offset forwardly from the stove structure in the upper part of said upright outer casing and connected adjacent its lower end with the flue opening, a dust box within the outer casing located between and spaced from the rear wall of the stove structure and the rear wall of said casing and having its upper portion formed as a rear flue header substantially aligned with the forward flue header, a plurality of flue tubes connected between said forward flue header and th upper flue header position of the dust box and extending substantially horizontally from front to back over the stove structure, and an outlet flue leading from th rear wall of said dust box at a point below the openings of said flue tubes into said dust box.

2'. A hot-air furnace comprising an upright outer casing of substantially rectangular cross section having an air intake opening through the lower part of its wall and having a heated air outlet at its top, said casing being provided through its front wall with a firing-door aperture and an ash-door aperture, stove structure disposed in upright relation within said casing and spaced from the walls thereof comprising a substantially rectangular ash-pit having an ash removal extension registering with the ash-door aperture and a substantially rectangular fire-pot mounted upon the ash-pit and having the inner face of its wall downwardly and outwardly tapered and a substantially rectangular firing-box mounted upon the fire-pot and having a fuel charging opening extension registering with the firing-door aperture, a crown sheet mounted on the top of said firing-box having its upper wall presenting a peaked top and with a flue opening forwardly from said peaked top, a laterally elongated flue header offset forwardly from the stove structure in the upper part of said upright outer casing and connected through its lower rear wall with the flue opening, a laterally elongated dust box within the outer casing located between and spaced from the rear wall of the stove structure and the rear wall of said casing, said dust box having its upper end formed as a rear flue header companion to the forward flue header and being provided at its lower end as a dust collecting clean out box, a plurality of flues connected horizontally between said forward and rear flue header portions spaced laterally from each other and extending from front to back above the top of the crown sheet, and an outlet flue extending from said dust box intermediate the clean out portion and the connection of the flue tubes therewith.

RANDALL MOYLE.

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