US2408991A - Warm air furnace - Google Patents

Description

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@ct 8, R946. e. E. MUMMA WARM AIR FURNACE Filed April 28, 1941 5 Sheets-Sheet 1 Wat.

G. E. MUMMA WARM AIR FURNACE Filed April 28, 1941 5 Sheets-Sheet 2 55/ 25 Z5 55 BY Gear QZMMZ/Im Oct. 8, 1946. e. a. MUMMA r 2,408,991

WARM AIR FURNACE Filed April 28, '1941 5 Sheets-Sheet 3 Oct. 8, 1946. s. E; MUMMA WARM AIR FURNACE Filed April 28, 1941 5 Sheets-Sheet 4 ll-zill f. ll Ill-MM [IQ- llT INVENTOR. 00/ 2/ w G. E. MUM-MA 2,408,991

WARM AIR FURNACE Filed April 28, 1941 5 Sheets-Sheet 5 Patented Oct. 8, 1946 WARM AIR FURNACE George E. Mumma, Winnetka, Ill., assignor to Sears, Roebuck and 00., Chicago, 111., a corporation of New York Application April 28, 1941, Serial No. 390,713

2 Claims.

My invention relates to warm air heaters, and has to do more particularly with a sectional heating device.

I realize that sectional heating devices have heretofore been suggested, as shown for example in Richardson Patent 1,072,499, September 3,. 1913; Allington 1,723,716, August 6, 1929; Westwick 2,157,643, May 9, 1939, and others.

However, I have evolved what appears to be a novel construction for a device of the type referred to, which I believe to have certain marked advantages over any device of this type heretofore known.

Particular objects of my invention are to provide a sectional warm air heater which may be constructed either as a furnace or as a circulating stove, which is especially simple in design, which is economical to fabricate, which provides increased heat exchange efficiency, and which, in general, is thoroughly satisfactory for the purposes desired.

Other objects and advantages will, no doubt, suggest themselves to those skilled in the art as the description proceeds.

Referring now to the drawings forming a part of this specification and illustrating a preferred embodiment of my invention:

Fig. 1 is a front elevation, partly in section, of a heating device embodying my invention;

Fig. 2 is a detail elevation of the lower extremity of the shaker handle;

Fig. 3 is a sectional view taken substantially along the line 3-3 of Fig. 1;

Fig. 4 is a fragmentary perspective view showing an end of a grate bar section;

Fig. 5 is a perspective view of a grate shaker arm;

Fig. 6 is a vertical sectional view of an intermediate section along the line 6-6 of Fig. 3;

Figs. 7 and 8 are sectional views taken substantially along the lines 'l| and 8-8, respectively, of Fig. 3;

Fig. 9 is a plan view of a front closure element for the foremost exhaust flue section;

Fig. 10 is an elevational view of the front cover;

Fig. 11 is a plan view of a juncture ring;

Fig. 12 is an elevational view of a juncture element forming a part of the main fire box;

Fig. 13 is a plan view of the rear flue connecting element;

Fig. 14 is an elevation of the rear closure element for the fire box;

Fig. 15 is an elevational view of one of the intermediate sections shown in Fig. 6;

Fig. 16 is an enlarged fragmentary perspective detail of a juncture ring shown in Fig. 12;

Fig. 17 is a similar view of a side wall liner forming a part of my invention; and

Fig. 18 is a similar view of the rear cover shown in Fig. 14 and showing detached from the cover a liner associated therewith.

It will be understood that the device shown in the drawings may be constructed either as a hot air furnace or as a circulating stove, the difference being principally one of size and proportion, in either event being surrounded by a casing through which air circulates in a manner well known in the art. The drawings show only the heating element itself which serves to transfer heat to the air circulated around it, the outer shell or casing being omitted for convenience of illustration.

The numeral iii indicates a front cover section which may conveniently be provided with a fire door II for the introduction of solid fuel, and a suitable forward extension [2 may be provided for this purpose, if desired (Fig. 3). It will be understood, however, that my invention is not limited to a hand stoking device but may, if desired, be adapted for automatic stoking and even for gaseous and liquid fuels. The front cover section may also be provided with an extension 15 which is provided with a door 16 for the ash pit. Suitable draft opening is provided for, as at H, with a closure therefor, such as damper l8 pivoted on pintles I9.

A rear cover sectionzfl is also provided (Fig.

Intermediate the front section 10 and rear section 20, I provide a plurality of duplicate sections 25. Any desired number of these intermediate sections may be employed, depending upon the heating capacity desired. Referring to Figs. 6 and 15, it will be seen that each of the intermediate sections includes a vertically elongated and laterally restricted chamber 26 which includes the ash pit portion 21, fire box portion 28, and a restricted gas portion 29, Fig. 6. The shape as illustrated in Fig. 6 is found very advantageous in promoting rapid travel of combustion gases and efficient contact thereof with the sur faces. Improved combustion is also facilitated by this shape. There is also effected a saving of metal. Abov the fire box portion 28 it will be seen that the section becomes extended or flared in width and narrower from front to rear, to provide a scutiform pouch 30 for gaseous products of combustion, this upper pouch portion being referred to generally by the numeral 3% (Fig. '7).

Elongated ports 3| permit the passage of gases of combustion from the fire box 28 into the flared section 30, baffles 33 being provided in order to force these gases into contact with the outer walls of the section. The gases flow out of the enlarged section 39 through slots 35 into a manifold 35, passing out through a flue extension Iii (Fig. 3) in the rear of the device.

The flared section 35 is provided with an arcuate slot 39 below the manifold 35, which permits transverse passage of air through the flared section 3!}, providing a large surface for heat exchange. t will be noted that the slots 35) follow the contour of the top of the combustion ch. ber, thus providing a heat exchange surface at th hottest portion of the chamber; also that the slot is sloped so as to inhibit collection of dust. soot and fly ash, which would act as an insulator.

Thus, it will be seen that each flared pouch section serves as a heat exchange fin. Not only is a very great surface provided by the arrangement shown, but also, by narrowing the flared sections, the velocity of the gases is increased, adding further to efficiency.

Each flared section 30 is provided on each side thereof with openings which are closed by means of doors 4!), suitable packing, such as asbestos rope, being provided around the edges of the doors. These doors are provided with nook-like portions 4! (Fig. 6) which engage studs 42 or the like formed on the inside wall of the flared portion 30. A lip 43 or the like may be provided on the outside of the doors 43 whereby they may be engaged by a suitable tool and removed for cleaning out any soot, fly ash, or the like which might collect in the passages of flared portion 39. However, it should b noted that by reason of the downwardly sloping walls 45 of the portion 3!], which slope down preferably at an angle of at least 45, fly ash will tend to drop by gravity out of these passages and hence will not readily collect so as to reduce heat exchange efficiency. Such collection is also minimized by the turbulence currents produced by the bailles and by the restricted width of the flared portion 38, producing high velocity of gases. Hence, cleaning will be only infrequently required.

The manifold 36 is closed at the front by means of a plate 48 (Figs. 1, 3 and 9) which is provided with cars 49, 49', through which extend tie rods 50 and 50, the front cover It! also having an upstanding ear 59" opposing car 49'. Similar ears 49a, 492). are provided on the flue section 37 through which the tie rods pass, while the rear cover section 25 has an car 490 opposing ear 491).

Additional tie rods 5| are provided on each side of the portion 28, suitable cars 52 being provided thereat on the front cover section It] and rear cover section 20. Of course, the tie rods may be disposed at other suitable points, such as inside the furnace in addition to or instead of at the points shown.

Between adjacent sections 25 are provided juncture or sealing sections 55 (Figs. 3, 7, 8, 12 and 16). These sections 55 are of H cross section, each having a groove 56, Fig. 16, on each side thereof which receives the edge of the adjacent intermediate section 25, rope asbestos or other suitable gasket material being disposed in the grooves to provide a gas tight joint.

On the inner flange of each of the juncture sections 55 I provide a cut out portion 5'! adjacent which is an upstanding hook-like portion 58 for retaining liners 69 (Figs. 3, 6, 8 and 17), the latter being provided with laterally extending ears ing the former, and a similar liner 64 (Fig. 8) is CLI attached to the front cover section is above the grate. It will be noted from Fig. 8 that the liners 60, B2 and 64 are vertically corrugated and are spaced from the inner walls of the furnace. These liners thus serve not only to protect the walls from overheating and possible disintegration but also provide vertical passages whereby air streams may flow from the lower portion of the furnace, heated, and continue into the upper portion, thus providing preheated secondary air for combustion of the gases distilled from the fuel bed, thus greatly adding to the efficiency of the device. The liners may, if desired, extend below the grate, in which case they will receive air rising from the ash pit along the sides of the grate and discharge it at the top of the liners.

Juncture rings 65 (Figs. 3 and 11) similar in cross section and in function to the elements 55 are provided in the upper or manifold portion of the device, circular ribs 66 being formed on the flared portion 36 of intermediate sections 25 to seat in said rings 65.

The grate is likewise formed in a plurality of sections 70, one grate section being provided for each of the intermediate sections 25. As best seen in Fig. 4, each grate bar has formed on each end thereof a U-shaped outwardly extending hanger flange H which is rotatably seated on a bearing stud 12 extending inwardly from the wall of the section 25 and preferably formed integrally therewith (Fig. 6). Each grate section 19 is thus supported at each end thereof. At one end shaking means is provided in the form of a shaker arm 73 (Figs. 3 and 5) which has a stirrup-like portion 15 encompassing the U-flange H of the grate. 'I'he stirrup 15 is made only slightly larger than the flange "H so as to form a relatively snug fit therewith, whereby rotation of each shaker arm rotates its corresponding grate section with substantially no play. Each shaker arm has a depending bar 16 which carries adjacent its free end a stud 11 which is journalled in an eye portion E8 of a grate connecting bar (Fig. 3). The bar 80 is suitably connected to a shaker lever 82 disposed in a convenient position to one side of the front cover section I0, and journalled thereto as at 83', and having a depending arm 84 pivotally secured to the connecting bar 89 as at 85.

It will be seen that I have provided an exceptionally advantageous arrangement. Substantially the entire organization may be cast, thus contributing greatly to low cost. A heater may be made of any desired capacity merely by providing the desired number of sections 25 and juncture elements. After a unit has been set up, if

7 any change in capacity is desired, it is only necessary to remove the tie rods and add or remove the necessary number of intermediate sections and juncture elements. Assembly and demounting is done very rapidly and conveniently, in

- view of the interlocking arrangement and tie rods. The front and rear sections may be interchanged without disturbing the rest of the organization.

The heat efficiency is also found to be greater as compared with similar devices heretofore known. Thus, I have found from tests that by reason of the large amount of heat exchange surface provided, according to my design, a saving of metal amounting to as high as 35 per cent may be efiected for a given heat output, as compared with standard cast iron warm air furnaces. Metal may be saved by reason of the fact that much thinner walled sections may be used than is possible with previously known structures, in view of the fact that, according to my invention, the products of combustion are carried away at such a great velocity that local overheating is avoided. Where such heat would be at all likely to occur, as adjacent the fire bed, protective liners are attached.

Various modifications may suggest themselves to those skilled in the art Without departing from the spirit of my invention, and, hence, I do not wish to be restricted to the specific form shown or uses mentioned, except to the extent indicated in the appended claims.

I claim:

1. In a heater apparatus, a plurality of similar component sections of which each comprises an integral casting designed for tandem assembly, each of said component sections including a lowermost portion having a horizontal bottom edgewall and a pair of opposite side edge-walls, said bottom and side edge-walls profiling correspondingly and proportionally an ash pit chamber and a fire chamber and including a junction-defining edging for abutment with the corresponding edging of adjacent component sections, reverse curve portion merging into the upper extremity of said side edge-walls and extending inwardly to form a Slight constriction thereat with edging flanges meeting centrally and defining an arch, relatively narrower side edge-wall portions merging with said reverse curve portions and flaring outwardly to extend beyond said opposite side edge-wall of said lowermost portion, thence extending vertically, and thereafter joining with a horizontal plane edge-wall portion to accordingly define the perimeter of a scutiform pouch, the vertical portions of said relatively narrower edgewall having opposite cleanout openings for affording accessibility to the interior of said pouch, coextensive opposite walls joining with the several of said narrower pouch defining edge-wall portions to form an enclosure constituting said scutiform pouch, wall means defining an arched transvers communication opening through said coextensive walls and serving as a heat exchange passageway, said coextensive opposite walls having also a circular flue duct over said arched opening communicating with the interior of said scutiform pouch, and fine deflecting fins extending from said wall means and continuing the arched curvature of said opening within said pouch for the purpos of deflecting flue gases which rise from said fire chamber into heat exchangin lapping engagement with said flaring edge-wall portions.

2. A section furnace component for tandem multiple assembly comprising an integral casting having fire chamber and ash pit defining wall sections at opposite sides and bottom of substantially rectangular outline, said wall sections curving at the upper extremity of the sides inwardly into a constriction and arch defining outline, relatively narrower edge-wall portions merging with said wall section at the region of said constriction and angling outwardly thence vertically and joining with a horizontal-plane narrower edge-wall portion to accordingly define the perimeter of a scutiiorm pouch, coextensive opposite walls joining with said narrower edge-wall portions to enclose said scutiform pouch, wall means extendtransversely through said coextensive opposite walls and defining an arched transverse communication opening therethrough for serving as a heat exchange passageway, said opposit walls also having a circular flue duct opening over said arched opening by communicating with said pouch, and flue gas deflecting means extending within said pouch and abutting opposite ends of said arched opening wall means to effect wiping contactual engagement outwardly of flue gases rising within said pouch from the region of said fire chamber.

GEORGE E. lVIUlVEMA.

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