US2476067A - Combined oil and gas range - Google Patents

Description

July 12, 1949, R M. SHERMAN 2,476,067

COMBINED OIL AND GAS RANGE Filed Feb. 26, 1944 2 sneaks-sheet 1 RaZsZanMMw 41 Min/ 9 MM R. M. SHERMAN 2,476,067

COMBINED OIL AND GAS RANGE 2 Sheets-Sheet 2 July 12, 1949,

Filed Feb. 2a, 1944 a r.lI||ll||||7 v 0 00000000000 0a o ooooooo r N OOOOOOOOOQO/ OO0O0OOO OO 4 0090000 000 DOOOOOOOCOO QQWODOOOOO OOOOOOODOOOODOOO OOOOOOWOODTuOOOOOOOOOOJOODO L Patented July 12, 1949 UNITED STATES ?ATENT OFFICE COMBINED OIL AND GAS RANGE Rallston M. Sherman, Glastonburmfionn.

Application February 26, 194i, Serial No. 5245,0512

1 Claim. 1

My invention relates to ranges, particularly but not exclusively to those having provision for performing cooking operations, such as baking, by heat derived from either oil or gas or from both simultaneously.

Heretofcre the attempt to heat the oven of a range by simultaneously operated gas and oil burners and secure satisfactory advantage of the adherent characteristics of each burner has proved unsuccessful. It has been found, that when heating the oven of a range by an oil burner, uniform heating of the oven, and consequently best baking performance, is secured by causing the products of combustion of the, burner to travel over the top Wall of the oven, down one of its lateral walls, and across its bottom wall, in contact therewith, and hence to the stack. On the other hand, it has been found that best results are secured by placing the gas burner beneath the oven, that is to say, in the passage below the oven for the products of combustion from the oil burner if the range is designed to heat the even by an oil burner as well as by a gas burner. It however has been found that placing the gas burner in this passage so seriously interferes with the draft tending to move the products of combustion of the oil burner through the passage, when the gas burner is in operation, that it is impossible satisfactorily to operate both burners. simultaneously. The attempt to overcome this defect by increasing the draft causes the products of combustion from the gas burner to fail to rise through the portion of the passage in contact with the lateral wall of the oven, and consequently under such conditions the gas burner will not tend to heat the oven uniformly. Further, the attempt to overcome this defect by placing the gas burner within the oven chamber has, with burners as heretofore constructed, failed to secure proper heating of the oven, for although best results with the gas. burner within the oven chamber aresecured when it is at the top of that chamber, at which position it is almost obligatory to place it to keepthe gas fumes and combustion products away from the food, it does not, when so placed, securea wholly satisfactory uniform heating of the oven chamber but results in a pronounced unsatisfactory sharply decreasing temperature gradient between the p and bottom portions of the chamber.

With a range constructed according to applicants invention, however, it is possible to operate the oil and gas burners simultaneously so that: the stove top may be heated to the desireddegree by the products of combustion "of the oil burner,

which latter also heat the oven, any further heat required for heating the oven being obtained by burning gasat theupper portion of the oven chamber in an improved way that heats the oven chamber uniformly. Further, with such a range the oven may be heated exclusively by either the oil burner or the improved gas burning instrumentality within the oven, this instrumentality also being highly suitable for broiling food placed in the oven. Thus this improved gas burning instrumentality not only serves for highlysuccessiul broiling andbaking but permits the oil-burner to be operated simultaneously therewith Without interference.

The above and further objects of the invention will be best understood from the followin description when read the light of theaccompanying drawings of an embodiment of the invention, the scope of which latter will be more particularly pointed out in the appended claims.

In the drawings Fig. l is a horizontal section of a range according to the invention on the line l-] of Fig. 2;

Fig. 2 is a vertical section on the line 2-2 of Fig. 1, illustratingperf-orma-nce of a baking operation in the oven Fig. 3 illustrates a detail of the range according to Figs. 1 and 2;

Fig. 4 is a vertical section of the oven chamber, corresponding to Fig. 2, illustrating performance of a broiling operation in the oven;

Fig. 5 is a plan on an enlarged scale, with parts in section and parts broken away, of the gas burning l-nstrumen-tal-ity, and associated parts, of the range according to Figs. 1 to 4 inelusive;

Fig. 6 is a side elevation, with parts in section and parts broken away, of the gas burning instrumen-ta'lity shown in Fig. 5'; and

7 is a section on the line l -iof Figs. 5 and 6.

Referring to the drawings, the range illustrated comprises. the conventional range casing i having a stove top 3, on which latter broiling and frying operations, and the like, maybe performed. Within the casingare walls forming an oven chamber 5, one lateral wall 1 of the oven being sufficiently spaced. from the corresponding lateral wall of the casing to form a compartment 9 in which is placed one or more combustion tube range oil burners 'll of common construction.

As shown, the top wall 13-, lateral wall It and bottom wall 11 of the oven are each spaced from the corresponding walls of-"the casing l to afford communicatingspacesbrpassages l9, 2| and 23 for removing the products of combustion of the oil burner from the compartment 9 and discharging them through an opening 25 in communication with the stack connection 21 carried by the back wall of the casing I. The hot walls of the combustion tubes of the oil burners, and the products of combustion in the compartment 9, serve to heat the adjacent wall of the oven, while the products of combustion passing through the space l9 serve to heat the stove top and the top wall of the oven chamber, the products of combustion in the spaces 2| and 23 further serving to heat the adjacent walls of the oven so that the latter, as viewed in Fig. 2, is in effect enveloped by hot gases serving to heat its interior uniformly.

As has hereinbefore been explained, according to the invention instead of placing in the space 23 beneath the oven a gas burner for heating it, or placing such burner elsewhere in the passages for conducting products of combustion from the oil burner to the stack, the gas for heating the oven is burned exclusively Within the oven chamber, a novel gas burning lnstrumentality which will heat the oven by radiant heat being employed for this purpose as hereinafter explained.

I-Ieretofore, in the attempt to heat an oven by burning gas within the oven chamber, an inverted Bunsen-type burner has been employed. Such burner, in effect, forms at the upper portion of the oven chamber a sheet of flame facing the bottom of that chamber. As a result the burner forms an intensely hot zone at the upper portion of the chamber, but because of the blue Bunsen flame being non-luminous fails to radiate heat downwardly. Further it has been found necessary with such a burner to cause the flame to burn substantially out ofcontact with the body of the burner lest improper combustion cccur'and cause generation of dangerous amounts of carbon monoxide gas, and in consequence the body of the burner remains relatively cool and, like the flame, fails to form a source of radiant heat of suflicient capacity to have any appreciable effect in heating the bottom portion of the chamber. As a result, with such a burner the bottom portion of the oven chamber, it has been found, tends to be heated almost exclusively by convection currents of the air or other vapors in the chamber, which air because the burner is at the top of the chamber does not readily circulate throughout the height of the chamber but tends to form a dead air space at its bottom portion, so that the upper portions of the chamber are unsatisfactorily over-heated and the lower portion unsatisfactorily under-heated.

As illustrated, the gas burning device according'to the present invention comprises a manifold 29 within the oven chamber at its upper portion for supplying gaseous fuel to a plurality of pipes 3|, which pipes at their free ends are closed by caps 33. As shown, the manifold and pipes are supported by bars 34 carried at their end portions by the opposite walls I and I of the oven, the pipes being received in notches 35 formed in the upper edge portions of these bars. As shown, each pipe is provided on its under side with a row of spaced perforations 36 so that gaseous fuel admitted to the pipe may discharge therefrom through downwardly facing openings provided by these perforations. For receiving the gaseous fuel discharged through the perforations 36 is provided a chamber 31 the walls of which, as shown, are formed of sheet' refractory material such as stainless steel. As

- illustrated, the walls of this chamber comprise the downwardly converging side walls 39 which it will be observed face downwardly as well as laterally so that when heated to incandescence, as hereinafter explained, they will emit radiant heat downwardly as well as laterally. Also, as shown, the walls 39 are joined at the bottom of the chamber by a relatively narrow wall 4|, the top of the chamber being closed by the pipe 3|. As illustrated, the upper edge portions of the sheet forming the walls 39 and 4| are curved to fit the upper portion of the pipe and at the top of the latter are welded to each other and to the pipe as indicated at 43. As shown, each of the opposite ends of the chamber is closed by an imperforate' plate 45 welded at its edges to the pipe and to the side and bottom walls of the chamber. The sheet forming the walls 39 and 4: of the chamber 31 conveniently is preperforated material, the perforations, indicated at 41, being of relatively small diameter and relatively closely spaced so as to provide, on the exterior surfaces of the walls, openings each surrounded by a small increment of those surfaces of greater area than that of the opening.

The gaseous fuel supplied the pipes; 3| is distributed to the chambers 31 by the rows of perforations 36 inthe pipes, which rows extend the full lengths of said chambers so that substantially uniform amounts of gaseous fuel will In operationv the amount of gaseous fuel supplied each pipe 3| is such, in relation to the total area of the perforations 41 of the chamber 31 associated with that pipe, that only sufficient gas is discharged through each perforation to form but a small button of flame in contact with that increment of the exterior surface of the walls of the chamber which surrounds the opening of the perforation on-that surface, as distinguished from the effect produced in the gas burner heretofore attempted-"to be employed in ovens with which the gas discharged burns out of contact with the body" of the burner. As a result, in applicants device thewalls of the chamber having the perforations 41 are heated to incandescence, and the exterior surfaces ofthose walls thus provide a source of radiant heat. I

The'gaseous fuel supplied the pipes 3| is mixed either with no air at all-or with insufficient air to support combustion of such fuel. Otherwise the fuel at the interior of the chamber would become ignited,.with the result that the perforatedwalls of the chamber, particularly their exterior surfaces, would not be heated to incandescence." If no air is admixed with the gaseous fuel, combustion is supported wholly by air at the exterior of the perforations 41, the distribution of the fuel afforded by these perforations being suchas to so reduce the amount of fuel discharged through each perforation that it burns with" a flame, of the general transparent blue remaining air necessary to support combustion being secondary air at the exterior of the perforations; In the sense that the gaseous fuel discharging from the perforations, unlike thegaseous fuel discharged by a Bunsen burner, contains, as just explained, no air or insufiicient air to make it burn at all, making it necessary in each case to burn by secondary air the fuel discharged from the perforations, said gaseous fuel in the appended claims for convenience in terminology is called oxygen deficient" fuel or gas.

For admixing the gaseous fuel with an amount of air less than that which will support combustion or cause the fuel to ignite in the interior of the chamber 3?, in the present embodiment of the invention the manifold inlet connection 49 is provided with a funnel-like head 51 carrying interiorly thereof a nozzle 53 for discharging gaseous fuel into such connection axially thereof so as to draw exterior air through one or more openings 55 in the immovable closure plate 51 of the head 5| for admixture with the fuel discharged from the nozzle. As shown, the head is provided with a rotatable cap 59 provided with one or more openings 0 I, each of which is adapted to be brought more or less into registry with one of the openings 55 for adjusting the amount of air admitted, while the amount of gaseous fuel supplied the nozzle may be regulated by the valve in the pipe 65 supplying such fuel to the nozzle. As shown, the manifold inlet connection 49 leads to the exterior of the oven through an opening G'l in the back wall of the oven, the walls of this opening affording suflicient clearance about the connection to permit an amount of air necessary for combustion of the gaseous fuel to enter the oven whether the air admission openings 55 are open to cause primary air to be admixed with the fuel or are closed to cause the fuel to burn Wholly with secondary air. As illustrated, the products of combustion from the gas burning device escape from the oven chamber through an opening 69 formed in its upper wall into the flue passage Hi and thence to the stack.

As an example of the improved gas burning device above described, but without limitation thereto, each pipe 3| may be a length of standard inch so-called wrought iron pipe which is about 1.05 inches outside diameter with a wall thickness of about 0.08 inch, the perforations 36 in the pipe being 0.12 inch in diameter spaced on centers inch apart, while the chamber 31 may be about 7 inches long with its bot-tom about inch wide and 2 inches below the bottom of the pipe, the lateral and side walls of the chamber being made of a sheet of stainless steel about 0.03 inch thick, consisting of 18% chromium, 8% nickel and 74% iron, which sheet has perforations 1? about 0.07 inch in diameter spaced on inch centers. By supplying sufficient amounts of ordinary city fuel gas, having a fuel value of about 550 B. t. u. per cubic foot, to cause the small button of blue flame at each perforation 47 to be of such diameter that it contacts at its periphery with the buttons at the immediately adjacent perforations, the exterior surfaces of the perforated wall of the chamber will be heated to about 1600 F. in about 7 /2 minutes and thereafter maintained at that temperature. Compared to the maximum temperatures secured, and the times required to secure them, with the inverted type of gas burner heretofore proposed, the temperatures secured by applicants device are remarkably high and the times required to secure them remarkably short, for seldom do the temperatures secured with said type of gas burner ever exceed 650 F. or require less than about 15 minutes to secure them.

The interior surfaces of the lateral walls of the oven chamber, and particularly those of the walls 1 and 15, which walls preferably are of relatively thin low carbon steeel, say about 0.03 inch thick, are preferably highly reflective as, for example, they may be bright chromium plated. This will cause the radiant heat emitted from the incandescent exterior surfaces of the side walls 39 of the gas burning device striking the lateral walls of the oven to be reflected downwardly as, for example, rays emitted along paths ll will be reflected along paths 13 toward the bottom of the oven. Preferably, also, for the same purpose the inner surface of the back wall of the oven and the inner exposed surface of the lining is of the oven door H are also highly reflective. Above the gas burning device is shown a reflector plate 19 preferably formed of metal having a polished chromium plated surface on its lower concave side for reflecting heat downwardly.

When the oven is arranged for baking, as shown in Fig. 2, there is preferably employed for further diffusing the radiant heat throughout the oven a heat diffusing plate 55! positioned below the gas burning device, which plate may be formed with one or more openings 83. As shown, the plate is carried by bars the ends of which are adapted to be received by the channel-shaped rack supports 8 carried by the walls 7 and lb of the oven chamber, so that the diffusing plate may be removed and may be positioned at different elevations to suit baking conditions. As shown, the reflector plate 19 is similarly carried and supported by bars 89 so that the plate may be removed for cleaning purposes.

The exterior surfaces of the walls of the oven chamber preferably are unfinished, so as to provide dark relatively rough surfaces that will readily absorb heat from the flue gases of the oil burner. The reflective surfaces afforded by the interior surfaces of the oven chamber act to prevent loss of heat through the oven walls from the interior of the oven chamber when the gas burner is in operation. Thus the oven surfaces are such as to facilitate absorption of heat from the flue gases from the oil burner, while at the same time effectively insulating the oven from escape of heat through its walls when the gas burner is in operation. It will be understood that the interior of the top wall of the oven also may afford a similar polished surface for insulating purposes, and where the reflector plate 79 is not employed such surface will also act to reflect the radiant heat downwardly.

In Fig. 4 the oven is shown arranged for broiling. Under these conditions the diffusing plate iii is removed, and a removable grid 91 for supporting the food to be broiled and an associated drip pan 93 are positioned below the bottom of the gas burning device on a removable rack 95 carried by the adjacent rack supports 81. The incandescent bottom walls 4! of the gas burning device, in conjunction with the incandescent lateral walls 39 thereof, and the action of the reflector plate is form a superior source of broiling heat comparable to and in fact superior to that of glowing charcoal.

As illustrated in Fig. 2, in the oven resting on its bottom is a thick plate 91 of substantially the transverse dimensions of the oven, this plate being say about /2 inch thick and formed of cast iron or aluminum or other material having a high capacity for absorbing heat. Preferably, the surfaces of the plate are unpolished so that it will absorb radiant heat emitted from the gas burn-

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