US2550081A - Air-heating furnace and hollow baffle structure therefor - Google Patents

Description

A ril 24, 1951 c. w. NESBITT AIR-HEATING FURNACE AND HOLLOW BAFFLE STRUCTURE THEREFOR 3 Sheets-Sheet l Filed April 26, 1947 C. W. NESBITT April 24, 1951 AIR-HEATING FURNACE AND HOLLOW BAFFLE STRUCTURE THEREFOR 3 Sheets-Sheet 2 Filed April 26, 1947 April 4, 1951 c. w. NE sBlTT 2,550,081

AIR-HEATING FURNACE AND HOLLOW BAFFLE STRUCTURE THEREFOR Filed April 26, 1947 3 Sheets-Sheet 3 29 J- 3 @fi fnz/en'r'" 6197071! Z0. eJAz LZ'Z FBI 7' I Patented Apr. 24, 1951 AIR-HEATING FURNACE AND HOLLOW BAFFLE STRUCTURE THEREFOR Clifiord Wade Nesbitt, Kalamazoo, Mich, as-

signor to Borg-Warner Corporation, Chicago, 111., a corporation of Illinois Application April 26, 1947, Serial No. 744,097

11 Claims.

The present invention relates generally to warm air heating furnaces, and it has more particular reference to an improved furnace radiator bafile arrangement.

The present invention contemplates a warm air heating furnace which is adapted for installation in a minimum of space especially a restricted space such as may be present in certain utility units which are installed in pre-fabricated and the smaller types of houses. A utility unit is a, compact arrangement which contains therein facilities for coupling the numerous fixtures of the kitchen, laundry and bathroom spaces of a house, and occupies a comparatively small space, having a cross-sectional area approximately 3 x 7% feet and usually extends from the floor to the ceiling. Such units are factory assembled and are shipped complete to the location of the building being constructed. A region in a utility unit is allotted to the heating equipment or furnace, and while said equipment may occupy a definite proportion of the cubage of said unit, nevertheless the furnace must be of minimum dimensions. Hence the furnace must be of an efficient type and be so constructed that there is a maximum of heating surface within a constricted or minimum of space.

While the present furnacearrangement is primarily intended for use in a utility unit as above suggested, it is not limited to such use and it is well adapted for installation in a cellar or other space in a house for the purpose of heating the rooms thereof.

The present invention contemplates the provision of a warm air heating furnace fabricated from sheet metal plates so as to comprise a suitable combustion chamber and effective means for heating air. In lieu of the usual exterior heat exchange radiator, there is a noval baflle arrangement between the combustion chamber and smoke outlet to materially increase the length of travel of the ignited gases or hot products of combustion from the fire pot beneath the combustion chamber and to raise the temperature of air being heated.

It is one of the principal objects of this invention to simplify the construction of a warm air heating furnace, such as contemplated herein, and to improve the efiiciency and operation of such furnace.

Another object hereof resides in providing a warm air furnace which includes a sheet metal casing, having a generally rectangular form, the rear wall of which has the usual chimney outlet, and spaced from this rear Wall by a plurality of vertically arranged baffles, is a combustion chamber which is defined by the front and side walls of said casing and one of said bafiies.

Still another object resides in the provision of a hollow bafile unit which extends between the top, bottom and side walls of the furnace body, the hollow portion of said bafile defining an air duct which extends through openings in the top and bottom of the furnace body. It is here noted that this novel baffle is employed in lieu of the usual radiator which is hung on the outside of the customary warm air furnace body.

The present baflle is formed of two identical metal plates which are welded together into a unitary assembly thereby adapting the structure for economical manufacture. Also the baffles are so constructed that they are reversible when being installed, that is, one baiile, which is the first bafile is placed in one position and the next or second similar baflie which is spaced from the first battle is up-ended or inverted. In this manner the direction of travel of the hot gases is reversed at each baflle' and an elongated heating surface is established which is to be contacted by air being heated.

Additional objects, aims and advantages of the present invention will be apparent to persons skilled in the art after the construction and operation of the heating furnace and radiator bafile arrangement is understood from the within description.

It is preferred to accomplish the numerous objects of this invention, and to practice the same, in substantially the manner hereinafter fully described and as more particularly pointed out in the appended claims. Reference is now made to the accompanying drawings that form a part of this specification.

In the drawings:

Fig. 1 is a vertical side elevation partly broken away, of a warm air heating furnace assembly such as contemplated herein.

Fig. 2 is an enlarged side elevation, partly broken away, of the furnace body showing the 3 radiator bafiles, the combustion chamber, and the fire pot.

Fig. 3 is a vertical section taken transversely through the furnace body along the plane of line 33 on Fig. 2.

Fig. 4 is a plan of the furnace body with the rear portion of the top broken away.

Fig. 5 is a perspective view showing one of the stamped sheet metal plates used in fabricating the novel baffle contemplated herein.

Fig. 6 is a fragmentary detail View.

The drawings are to be understood as being more or less-of a schematic character for the purpose of disclosing a typical or preferred form of the improvements contemplated herein, and.

in these drawings like reference characters identify the same parts in the different views;

Referring first to Fig. 1, it will be seen that the furnace assembly A is mounted on a hollow base B of generally box-like form which hasa skele-. ton frame comprised of vertical and horizontal angle metal strips [0, H], which is closed by vertical walls H and has an open front l2. Within this'hollow base there is a suitable blower 13, having an upwardly pointing discharge nozzle 13a to direct extraneous air upwardly toward the furnace body and into air ducts of the baffles, as will be later explained herein. Immediately back of the open front there is a conventional air filter l4 through which air is drawn into the base through the open front 12 by means of the blower l3. It is contemplated, however, that the front may be closed and an air ingress opening mad in the bottom or another wall with the air filter back of such opening. The base 13 may rest upon the floor, although it is preferred that the entire furnace structure be supported on angle pieces forming the framework of a utility unit such as hereinbefore mentioned.

The furnace assembly A embodies an outer shell of box-like form which comprises a plurality of horizontal and vertical angle metal strips [6, 16, forming a skeleton frame the vertical portions of which are closed by panels Ilia. The shell has an open top l6band there is a relatively large opening in its bottom which communicates with the hollow base B through which theblower nozzle l3a protrudes so that the aircurrent created by the blower is directed upward past the furnace body to be heated and is then discharged through open top 1612 into a plenum chamber or other structure for distribution to the rooms.

The furnace body C of box-like form is supported in any suitable manner within the hollow shell, and connected to its lower region there is a fire pot 11. In the arrangement shown in Fig. 1 the fire pot is supplied by a conventional oil burner l8a, while in Fig. 2 a gas burner vl8.is

shown, it being understood that either type of fuel may be used in the furnace contemplated herein.

The furnace body is comprised of a plurality of vertical walls or panels I9, the rear wall having a flanged smoke outlet or aperture 20 for discharging the products of combustion into a pipe 2| leading to a chimney or other flue.

The top, v22 of the furnace has downturned fianges'fitted (detailed in Fig. 6), there is a large circular open ing 26 in the bottom 24 with an outwardly flanged throat 21 in which the cylindrical fire pot H is received. A perforate ignition chamber Ila is supported in the fire pot and has an open top through which the flames pass upward into the combustion chamber 28 comprising the forward or front region of the casing or housin as will be seen by reference to Fig. 1. In the gas burner type shown in Fig. 2, the fire pot I! has a slightly different contour than that used with the oil burner, and in lieu of thecircular flanged-throat the. bottom wall has its front portion cut away to provide a large opening 26a of preferably rectangular contour. 7

It is contemplated that the panels defining the verticalwalls; as well as the top and bottom of the furnace, be fabricated from heavy sheet metal plates ofa suitable gauge and Welded together to provide air-tight and gas-tight joints or seams.

These plates may be economically produced by any well-known stampin method and when assembled they provide the body of the furnace into which the hot ignited gases pass from the burner through the bottom opening to rise and expand in thecombustion chamber 28.

As hereinbefore stated, an important feature of this furnace resides in providing novel bafiling means encompassed within the walls of the furnace, said baffling. means being constructed in a manner so that air beingheated passes through said bafilingmeans from the exterior of the furnace beneath the bottom' 24.. and will be discharged in a heated state through the slot-like openings 23 in the top 22. The bafiies, for the sake of economy, as well as for the purpose of providing an efiicient air heating means, are made of identical sheet metal stampings, two ofwhich are united by welded seams. These baffles are set upright in parallel spaced relation to each other, and entered from side to side and from thetop to the bottom of the furnace body C. The exterior contour .of a baffle is such that in structures where two baflles are usedas shown herein, one baffie may be arranged in an inverted position with respect to the other baflle thereby providing a circuitous path which effects a lengthening of the distance traveled by the ignited gases ,and products of combustion to the-discharge opening 28.

Since the baffles are identical it will be sufficient to describe one. structure in detail. A baffle comprises a sheet metal plate D-having a generallyrectangular form asshown in perspecti'vein- Fig..5, the metal plate being stamped to define'therein a. channel which extends longitudinally of-the plate. This provides an elongated shallow dished portion 29 extendingfrom end to end of the plate. Atthe longitudinal rims of this dishedport-ion 29 there are elongated fins 30- whichare in the normal-plane of the plate, and it willbe seen-that these fins extend unbroken to one end of the baflle plate D while at the other end of the plate said fi'ns'have recessed regions 3!, which are madebycutting away portions of the plate so that when the. baffle is installed in the furnace these recessesi 3! provide transverse passages for permitting the travel of the hot products'of combustion past the baffle. The

margins of fins 38 have elongated lateral flanges 32 and at one end of the plate the fins which are not cut away, there are short flanges 33. The channel or dished-portion 2.9 has ends formed in a bottleneck manner to provide constricted regions 34 at the inlet and discharge ends of each baffle unit. I

After plates D have been formed as shown i perspective in Fig. 5, two of such plates are placed in superimposed relationship, and since they are identical, the fins 30 will lie in intimate surface contact with each other and are arranged with their recessed portions 3! in registry at one end of the bafile. The fins are then welded in any suitable manner, preferably by a continuous seam, to provide a gas-tight and unitary assembly. The two channeled or dished portions of the plates together define air ducts E longitudinally through the baffles for the air being heated.

The front baffle, which is in aposition farthest from the smoke outlet 20, is placed close to the upper rear edge of fire pot I! so that it provides the rear wall of the combustion chamber 28. This front bafile is mounted in an upright position in the casing or housing with its recessed portions 3| uppermost or at the top of the furnace body. The lateral flanges 32 and 33 of this remote baffle rest against the inner surfaces of the vertical walls l9 and the bottom 24. The next or intermediate baflle is set upright in the casing between the first baille and the back or rear wall of the casing, but it is arranged in inverted position, with the recessed portions 3| of the fins lowermost or at the bottom of the. furnace body. This second or intermediate bafile is secured to the walls of the casing by welding or otherwise in the same manner as described with reference to the first or remote baffle. The

ends of the dished portions of the bafiles preferably project through the rimmed openings 23 and 25 in the top and bottom of the casing as clearly shown in Figs. 1 and 2, and since the parts of each ballle are assembled by a welding seam on the fins leakage of gas into air-ducts of the bailles is prevented.

The ignited products of combustion from the fire pot and burner will rise in the combustion chamber 28 and will travel to the top thereof where they find egress past the adjacent bafile through the recesses or passages 35 which are formed on each side of the upper portion of said baffle by the recessed portions 35 of the fins. These hot products of combustion must then travel downward between the two baffles as shown by the arrows (Fig. 2), and then through the passages 35a at the bottom of the inverted rear ballie, after which the products of combustion travel upward and then pass out of the furnace body through the smoke or discharge outlet 20 to the chimney or the flue.

It will be seen that while the furnace is comparatively small in cubage there is an extremely long travel of the products of combustion entirely within the confines of the furnace body, due to the baille arrangement, thereby materially slowing down the velocity of these combustion gases so that considerable heat is absorbed therefrom by the metal plates forming the baffles. Also the plates forming furnace body C become quite hot by contact with these hot gases and hence are raised to a high temperature.

The blower I3 in the base section B creates a current of filtered air which is directed upwardly against fire pot I! and around the walls of furnace body C, and also a portion of this air enters the inlet necks 34 at the bottoms of the baffles. This air current travels upwardly in the air ducts E and expands in the wide regions of said ducts. The bottleneck arrangement tends to hold back the air being heated within the baflles so that said air will absorb a considerable portion of the heat units by intimate contact of the metal surface by the air ducts. Any desirable arrangement may be made for the distribution of the heated air after it reaches the top of the shell from around furnace body D as well as the hot air which is emitted from the discharge throats of the baflles.

The bottleneck shape of the baflle unit air ducts is one of the important features of this invention because it increases the efliciency of heat extraction. The air to be heated, entering the larger region of the air ducts expands and increases in volume because of the heat absorbed by it, and the restricted outlets retard the flow of air, thus tending to increase the air contact time and the heat transfer. The arrangement of this furnace enables the condensing of a maximum heating surface into a comparatively small unit and avoids the use of the usual large exterior radiator employed in heating furnaces of the warm air type generally in use. I

While this invention has been described in detail in its present preferred form or embodiment, it will be apparent to persons skilled in the art, after understanding the improvements, that, various changes and modifications may be made therein without departing from the spirit or scope thereof. It is aimed in the appended claims to cover all such changes and modifications.

What is claimed is:

1. In a space heater and the like a plurality of sheet metal walls defining a closed hollow casing, one of said walls having an outlet aperture; a plurality of structurally independent spaced baflles arranged transversely in the portion of said casing adjacent said apertured wall and extending to the side walls of said casing, the bafile which is farthest from said apertured wall together with the other casing walls defining a combustion chamber; means supplying ignited gases to the lower region of said combustion chamber; said baffles being cooperatively associated with each other and with the casing walls for directing the products of combustion in a circuitous path in transit from said combustion chamber to said outlet aperture; said baffles being of hollow section to define air ducts extending through the upper and lower casing walls and being adapted to pass extraneous air upwardly through said casing whereby said air is heated by the products of combustion moving through said circuitous path; the ends of said baffles having restricted throats defining inlet and discharge regions adapted to retard passage of extraneous air therethrough; recessed regions adjacent the ends of said bafiles defining passages for products of combustion past said baffles; and means for creating an air current directed towards the inlet regions of said air ducts.

2. In a space heater and the like comprising a plurality of sheet metal walls defining a closed hollow casing, one of said walls having an outlet aperture; a plurality of structurally independent elongated spaced bafiles arranged transversely in the portion of said casing adjacent said apertured wall and extending to the side walls of said casing, the baflle which is farthest from said apertured wall together with the other casing walls defining a combustion chamber; means supplying ignited gases to the lower region of said combustion chamber; said baffles being of armour.

hollowrlsection. for .1 defining air ducts therethrough; said: hollow bafiles. extending through the..upper .and: lower casing. .walls and being adapted to effect the fiowv of extraneous airupwardly through .said .casing whereby said air is heated: by. the products .of. combustion moving through said. circuitous path; said 'bafiles at the sides of. said air. ductsdefining longitudinalside fins extending to opposite side walls of vsaictcasing, said fins having alternately arranged interrupted regions adjacent .the: upper. and .lower chamber walls wherebythe products of xcombuse tion are. directed in. a circuitous path through said chamber. to said outlet; .and means for creating. anzair current directed totheinlet regions of said-.baflle air ducts.

:3. As a new article of manufacture, a baftle for warm .air furnacesandthe. like, said.baflie having. an air. duct therein. and. being. formed of twoidenti'cal sections, each said .section comprise. ing azsheet. metalplate having a generally rectangular shape; ashallow depressed region .013- set laterally from the plane, of said plate, said depressed region extendingfrom end. to end of said plate between the sides thereof and having end portions of less width. than. its intermediate region; the-portionsof said plate lying. along.- side the rim of .said depressed region. .defining oppositely projecting longitudinal fins; and lateral fianges at themarginsof said fins; said two sections being arranged with .said finsin contacting relation to each other and secured together by a gas-tight joint with the depressedregions of the two plates facing each other thereby to define the aforesaid air duct insaidbafiie.

4. As anew article of manufacture, a bafiie for warm air furnaces'and the like, saidv baflle having an air duct therein, .comprising a sheet metal plate having a generally rectangular shape; a longitudinal open .channelformed in said plate between itssides, said channel extending from end to end of said plate and having constricted end regions; oppositely projecting longitudinal fins along the rims of said channel, said fins being interrupted at aside of one of said constricted end regions; and closure means extending across said channeland secured tothe portions of saidplate alongside said channel, whereby to define the aforesaid air duct through said bafile.

5. As a new article of manufacture, a baffle for warm air furnaces and thelike, andhaving an air duct therein which is characterized by a bulged central portion and restricted end portions, said baiile comprising a sheet metal plate having a generally rectangular shape; a shallow depressed region offset transversely from the plane of said plate, said depressed region extending from end to endof saidplate between the sides thereof and having portions at each end of less width. than its intermediate region, said end portion defining between themsaid bulged. central portion; oppositely projecting longitudinal fins along the longitudinal rims .of said. depressed region;andasheetmetal closure plate secured to said fins in bridging relationship to said depressed region, whereby said two plates define the aforesaid air duct through said bafile. v 7

6. A bafile memberfor retarding discharge of hot products of combustion from a furnace of the warm air type and adapted for installation in the furnace between the combustion chamber and the smoke outlet,said baffle member comprising two' identical sheetmetal plates havinggeneraHyrectangular contour, each plate being formed with a longitudinal channel extending from end .to end thereof with a wide intermediate region; fiat regions at the sides of said channel; said plates being arranged in superimposed relation with saidfiat regions contact ing each other and anchored together by welding, said channels together defining a longitudinal duct with a wide expansion chamber and restricted end regions for passage through said bafile of extraneous air to be heated, the portions of-said plates which define said channels being adapted to separate the air being heated from the hot products of combustion in transit to. the smoke outlet of the furnace. Y i

'7. A bafile member as defined in claim 6 wherein the. end regions of saidchannels are. of..less.

cross-sectional area than the intermediate re.- gions whereby to retard passage of air through said baflle.

8. A bafiie member as defined in claim 6 wherein the fiat regions of the plates define fins which are recessed adjacent one end for passage of products of combustion outside of and past the baffle member.

9. A bafiie member as defined in claim 6 wherein the channels are constricted at each end, and the flat regions have recesses proximate one end for passage of products of combustion outside of and past the baffle member.

10. A space heater and the like comprising, a plurality of sheet metal walls defining a closed casing having an outlet inonewall; a plurality of structurally independent upstanding bailies arranged in separated spaced order in the portion of said casing adjacent said outlet wall, one of said baffles and said outlet wall defining a combustion chamber; means supplying ignited gases to the lower region of said combustion chamber; each baiile comprising a sheet metal plate of generally rectangular shape; a longitudinal open channel between the sides of said plate and extending from end to end thereof, the end regions of said channel being shaped to define restricted throats; oppositely projecting .fins along the longitudinal rims of said channel, and closure means extending across said channel and secured to said fins thereby to define an air duct through said baflie; said air ducts extending through upper and lower walls of said casing and being adapted to pass extraneous air through said casing to be heated in said ducts by the products of combustion moving through a circuitous path; and recessed regions at the end of alternate bafiies alongside said throats defining passages for products of combustion to travel ina circuitous path past said bafiies to .said outlet.

11. A space heater comprising a plurality of sheet'metal walls. defining. a hollow body having a combustionchamberat oneend region and an outlet at-the opposite end region; .and a heat exchanger in said 'hollowrbody comprising horizontally spaced elongate tubular members of flat I cross-sections defining "vertical bailies having air alternately arranged respectively at the upper and lower regions of successive bafiies whereby said baffles define a circuituous path for the flow of hot'gases from said combustion chamber and past said baffles to said outlet, the throats of said baffies extending through the top and bottom walls of said hollow body; and means for directing extraneous air to the lower inlet regions of said baffle air ducts whereby such extraneous air is heated in transit through said ducts in intimate association with the hot gases flowing in said circuituous path from the combuston chamber past and around said battles to said outlet.

CLIFFORD WADE NESBI'IT.

REFERENCES CITED The following references are of record in the file of this patent:v

UNITED STATES PATENTS

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