US2534832A - Fabricated refractory metal firebox - Google Patents

Description

Dec. 19, 1950 c. E. SCHINMAN 2,534,832

FABRICATED REFRACTORY METAL FIREBOX Filed Sept. 20, 1947 2 Sheets-Sheet 1 33 20 45 INVENTOR. 34 6%; E. JcH/NMfi/v 52 JTTOBNEYJ 19, 1950 c. E. SCHINMAN 2,534,832

FABRICATED REFRACTORY METAL FIREBOX Filed Sept. 20, 1947 2 Sheets-Sheet 2 jQ /QJ 2a 1 30 0- W04 Patented Dec. 19, 1950 FABRICATED REFRACTORY METAL FIREBOX Carl E. Schinman, Seattle, Wash.

Application September 20, 1947, Serial No. 775,202

2 Claims.

This invention relates to furnaces and it has reference more particularly to improvements in firebox construction, and especially to fireboxes as applied to domestic furnaces that are fired with oil by means of gun type burners; it being the principal object of this invention to provide an improved type of firebox, whereby furnace heating efiiciency will be materially increased.

More specifically stated, it is the object of my invention to provide a novel firebox structure of stainless steel, designed to receive and shaped to fit the flame from the blast tube of the burner; a firebox which will attain a relatively quick rise to its peak temperature, giving most satisfactory burning operation, the highest heating efficiency and greatest fuel economy.

It is also an object of the present invention to provide a firebox structure that eliminates the need for or use of the usual fire-brick or refractory linings in firebox chambers, and, in that way, makes available the maximum heat radiating surface of the firebox.

Yet another object of my invention is to provide a firebox of stainless steel that is made in sections which, when occasion requires it, may be passed through a furnace door and assembled within the firebox chamber withhout requiring removal of any parts from the furnace or any reconstruction or alteration thereof. Furthermore, to provide a sectional firebox structure, the parts of which may, if desired, be assembled in part and placed in the furnace firebox through its doorway, for final assembly.

Still further objects of the invention reside in the details of construction of the variou parts embodied in the present firebox structure, and in their mode of assembly.

In accomplishing the above mentioned and other objects of the invention, I have provided the improved details of construction, the preferred forms of which are illustrated in the accompanying drawings, wherein Fig. 1 is a vertical cross section of the base portion of a domestic furnace of a typical form of construction, equipped with a stainless steel firebox structure, embodied by the present invention.

Fig. 2 is a horizontal section, taken substantially on the line 22 in Fig. 1.

Fig. 3 is a cross-sectional detail of the lower end portion of the present firebox structure taken on line 3-3 in Fig. 2.

Fig. 4 is a perspective View of the firebox structure, with parts made and assembled in accordance with the present invention.

Fig. 5 is a longitudinal, sectional detail taken on line 5-5 in Fig. 6, of a part of one of the le members and parts of adjacent wall sections of the firebox, as joined and supported thereby.

Fig. 6 is an inside View of the parts as assembled in Fig. 5.

Fig. '7 is an enlarged, horizontal section taken on the line 11 in Fig. 6.

Fig. 8 is a detail illustrating the manner of assembling one of the leg members with hook flanges of adjoining wall sections of the firebox.

Fig. 9 is a horizontal, sectional detail of a front portion of the firebox.

Referring more in detail to the drawings- In Fig. 1, I have shown the lower portion of a typical form of domestic furnace equipped with a firebox embodied by the present invention. In this view, l0 designates the combustion chamber enclosed by the furnace walls or shell ll; entrance to the chamber being through a doorway, as designated at H2 in Fig. 1; this doorway being equipped with a door I3.

Within the lower portion of the combustion chamber is located the firebox embodied by the present invention, designated in its entirety by numeral l4. Extended horizontally into the furnace through a housing l5 applied .to or formed as a part of the front wall of the shell, is the blast tube It of an oil burner designated generally by reference numeral [1.

The present firebox structure [4 is shown best in Figs. 1 and 4 as comprising a substantially cylindrical housing, of lesser diameter than that cylindrical part of the furnace shell in which it is contained. Also, it is shown as being so located in the furnace as to provide substantial air space between its walls and the shell. The walls of the shell around the firebox are not lined with fire brick as is the usual firebox, but are exposed to the heat radiating from the firebox. The present firebox is made of stainless steel, or a suitable like material, and is made in sections. It comprises a back section 20, opposite side sections 2l2l' and a front panel or section 22, all of which parts are independently formed and are adapted to be assembled in groups or to be applied individually to the combustion chamber of the furnace through the doorway l2 for final assembly within the furnace, as will presently be explained.

In the present preferred form of construction, the back section 20 comprises a single, rectangular piece of stainless steel plate, uniformly curved between its opposite, vertical side edges, as noted in Fig. 2, to conform substantially to the furnace shell curvature, and is formed along the vertical side edges with outwardly and then backwardly turned hook forming flanges 25. These flanges extend from even with the bottom edge of the plate to just short of the top edge where they are cut ofi at a slight angle, as noted at 25 in Fig. 8.

The opposite side sections 2| and 2| of the firebox are of the same height as the back section and, likewise, are made from sheets of stainless steel, rectangular in form and each formed along its opposite vertical edges with outwardly and backwardly turned flanges or hooks 25 like those formed on the back section. These side sections, also, are curved as noted in Fig. 2 to conform substantially to the cylindrical curvature of the shell.

The front section or panel 22 comprises a fiat, rectangular plate, somewhat greater in height than the side sections and relatively narrow, as noted in Fig. 4. This plate is formed along its opposite side edges with hook-flanges 25 that are outwardly then inwardly turned, like the vertical edge flanges on the back and side sections. These flanges 25 of plate 22 terminate short of the top edge of the plate and, like those of the other plates, are beveled oil at their upper ends, as shown, for a purpose presently understood. Formed in the plate 22, near its lower end, is a circular opening 23 bounded by an outturned flange 23, designed to receive the blast tube of the burner therethrough as in Fig. 2, and at opposite sides of this opening are slots 24-24 for reception of the burner anchor straps later to be described.

At their lower horizontal edges, the sections 25, 2| and 21, have inturned horizontal flanges '35 which are best shown in Fig. 3, and supporte' upon these flanges is a bottom plate 32, of stainless steel, which closes the lower end of the firebox. This plate has an upturned peripheral flange 33 that fits closely to the sections 28, 21-2!" and 22, and the plate operates to a certain extent to establish and maintain the shape of the housing as it is shown in Fig. 2. The

plate 32 preferably has a circular, downwardly dished portion of substantial 'diameter *as shown in Figs. 1 and to give it rigidity. When pressed into place, it is retained by bosses 34 pressed inwardl from the side walls.

The various wall forming sections 26, 2'|--'2|' and 22 which constitute the firebox structure are supported and also held in their assembled relationship by four metal legs '49, each of which comprises a straight strip of metal, with 'opposite longitudinal edge flanges 4'|4| bent back and then toward each other as noted best in Figs. 2, 6 and 8, but leaving open space between the edges of the flanges. The length or these legs is slightly more than the height of the wall sections and aside from serving to join adjacent edges of the sections, they serve also as legs whereby to support the firebox at a desired elevation above the bottom of the furnace as noted in Fig. 1.

It is to be pointed out also, as a detail of construction that facilitates the assembly of the leg portions with the wall sections, that each of the wall sections is formed, parallel with each of its edge flanges or hooks and spaced slightly therefrom best shown in Figs. 2 and 7, with 'an outwardly offset ridge or bead '45. When the flanged edge portions of two sections are brought properly together for joining, the ridges 45 will 'be spaced apart a proper distance to receive a leg 40 between them and they operate to some extent in assembly of legs and sections, as guides for directing the lower end of the leg over the beveled upper ends of the hook flanges 25.

To assemble the parts of the firebox, it is most practical to first join the back section 20 and a side section 2| by bringing the hook equipped side edges thereof into proper relationship for joining and to then slip the lower end portion of one of the leg members 40 into the guideway provided by the coacting ridges on the plates as has been illustrated in the detail of Fig. 8, and then push the leg down over the beveled ends of the hook flanges 25 and down the full length of the flanges until the leg extends the proper supporting distance beyond the lower edges of the plates, for example, as shown in Fig. 6. Then the other side plate is assembled with the back plate, in a like manner, and secured by another of the leg members 40. Finally, the front panel 22 is brought into position between the forward edges of the opposite side plates 2! and 2| and is secured by the application of the two front leg members so that the assembled structure will then appear as shown in Fig. 4.

After the legs have been properly applied and have been extended downwardly below the plate edges to the amount required, they may be secured against any relative upward slipping on the flanges 25 by indenting their flanges 4| or by pinching portions thereof inwardly against the leg, for example, as has been shown at in Figs. 5 and '6. To insure that each leg may be held extended a length equal to that of the others, and to make possible an easy determination of that length, the legs are graduated by marks :at half-inch intervals along their lower 'end portions as shown at 5| in Fig. 6.

After the legs 4|! have thus been assembled with the firebox housing sections, the bottom plate 32 is placed in the housing and pushed into place against the supporting flanges 30 as in Fig. 3, where it will be held by the bosses 34.

The front panel 22 which has no inturned flange at its lower edge is then adjusted up or down to brin the opening 23 therein to a proper level for reception of the burner blast tube 16. With the firebox approximately in position in the furnace, the blast tube ['6 is extended through housing l5 into the plate opening 23 as shown best in Fig. 3. The entrance to housing I5 is then bricked in about the blast tube, as shown at 58. i

In order that the firebox may be held in place, I then extend anchor straps 58 along opposite sides of the blast tube and anchor them at their inner ends in the plate slots 24-24 as at 6| in Fig. 2, and at their outer ends turn them back over the outer end edge of a sleeve that is applied about the blast tube to retain a heat insulating material.

This firebox construction makes possible the partial assembly of parts outside the furnace, and their passage into the furnace through the doorway, for final assembly by reaching through the doorway. Thus, the firebox may be readily applied to alread existing furnaces without any material trouble.

The particular advantages of this type of stainless steel firebox construction, aside from cost, reside in the long life of the structure; the fact that the steel allows the firebox to attain its peak temperature quickly and to radiate heat from its sides and bottom to the furnace walls. By its 5 use, fire brick linings are eliminated, thus giving additional radiating surface in the furnace.

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

1. A firebox structure of the character described comprising a plurality of rectangular wall forming sections of sheet metal adapted to be joined edge to edge, by vertical joints, to form a substantially cylindrical housing; each of said wall forming sections being formed with a longitudinal bead parallel with and adjacent each vertical edge and having each edge formed in a back-turned hook-like flange parallel to said bead, and leg-forming strips, with their opposite, longitudinal edges turned back in hook-like flanges, applied to the adjacent edge flanges of adjoining sections in a slip joint assembly and disposed between the beads of the joined sections, said leg-forming strips being longitudinally adjustable and adapted to be extended below the lower edges of assembled sections as supporting legs for the said firebox structure and a bottom Wall fitted in the base of said housing and some of the side wall sections having inturned flanges at their lower edges for support of said bottom wall.

2. A firebox structure comprising a plurality of rectangular side wall forming sections of refractory sheet metal, each with its vertical edges formed in back turned hook-like flanges, and leg forming members with opposite longitudinal edges turned back in hook-like flanges, applied to the edge flanges of adjoining sections in a slip joint assembly, and adjustably extended below the lower edges of the assembled sections to serve as supporting legs for the structure; the opposite side sections of the structure having inturned flanges at their lower edges, and a bottom wall applicable to the firebox as provided by the assembled sections, through its open upper end and supported on said inturned flanges, to close the lower end of the firebox and to retain it in a predetermined shape.

CARL E. SCHINMAN.

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

UNITED STATES PATENTS Number Name Date 1,016,390 Beadle Feb. 6, 1912 1,757,664 Gohmann May 6, 1930 1,959,035 Noble May 15, 1934 2,240,367 Fernholtz Apr. 29, 1941 2,244,314 Powers June 3, 1941 2,299,154 Lair Oct. 20, 1942 2,329,920 Loveley Sept. 21, 1943

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