US3528399A - Gas cooking oven - Google Patents

Description

United States Patent [72] Inventor Richard L. Perl Mansfield, Ohio [21] Appl. No. 648,483 [22] Filed June 23, 1967 [45] Patented Sept. 15, 1970 [73] Assignee The Tappan Company Mansfield, Ohio a corporation of Ohio 54 GAS COOKING OVEN 12 Claims, 7 Drawing Figs.

[52] US. Cl 126/21, 126/273 [51] int. Cl. F24c 15/32 [50] Field ofSearch 126/19, 21, 21A, 273, 41

[56] References Cited UNITED STATES PATENTS 3,090,371 5/1963 Davis 126/2l(A)UX 3,122,134 2/1964 Reeves 126/41 3,416,509 12/1968 Huebler et al. 126/21 FOREIGN PATENTS 662,210 12/1951 Great Britain ABSTRACT: A single-cavity gas cooking oven having a top burner configuration in which two blue flame burner tubes are angularly adjustable to direct flame at each side either below or above stationary shields. The flame is above the shields for baking, with the heated products caused to flow to a bottom collector duct over the walls either interiorly or exteriorly through a surrounding wrapper. The flame is below the shields for broiling, with flue products exhausted through a top collector duct, the two ducts being damper controlled. The oven is also operated for self-cleaning with the flame below the shields and only the bottom duct used for both radiant and convective heating within the cavity. The oven is powered by blower means for forced air supply to the burner assembly and the selected exhausting of the cavity, with both inlet and outlet fans preferred. The oven exhaust is brought into heat exchange relationship to the incoming air supply within a rotating regenerator wheel.

Patented Sept. 15, 1970 Sheet 2 of2 RICHARD 1.. PERL ATTORNEYS GAS COOKING OVEN This invention relates to an improved construction for a single-cavity, gas-fired cooking oven.

It is a primary object of the invention to provide such an oven having a top burner configuration which can selectively be used either primarily as a radiant heat source for broiling and the like within the oven cavity or to heat the cavity surfaces primarily by convection, with the last operative condition appropriate for baking and the like without significant radiant effect on the food being cookedor heated. The new construction can, accordingly, provide in the same cavity all of the operations normally carried out in a domestic oven with only a top burner assembly.

Another object of the invention is to provide such an oven in which combustion air is supplied to the burner configuration under pressure, together with the gaseous fuel under pressure to be combusted, and the heatedproducts are exhausted substantially directly from the cavity in such broil condition of operation or at a relatively remote location after circulation over the cavity walls in the second noted condition of operation.

It is an additional object to provide a gas cooking oven having a top burner assembly which is adjustable to vary exposure of the flame thereof with respect to the normal placements of food articles and the like to be heated in the cavity.

It is a still further object of the invention to provide such an oven in which inlet air to the burner assembly is supplied in heat transfer relationship to the heated products exhausted from the oven, thereby to lower the temperature of the ultimate exhaust to a level tolerable withina kitchen-and the like even at temperatures within a heat-cleaning range above approximately 750F.

Other objects and advantages of the present inventionwill become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends the invention, then, comprises the features hereinafter fully described and particularly pointed out inthe claims, the following description and the annexed drawings setting forth in detail certain illustrative embodiments of the invention, these being indicative, however, of but a few of the various ways in which the principle of the invention may be employed.

In said annexed drawings:

FIG. 1 is a sectional view of a basic oven construction in accordance with the present invention;

FIG. 2 is a transverse sectional view of the oven at the plane of the line 2-2 in FIG. 1;

FIG. 3 is a fragmented transverse section as viewed from the plane of the line 3-3 in FIG. 1 and on a relatively enlarged scale;

FIG. 4 is a fragmented horizontal section the plane of which is indicated by the line 4-4 in FIG. 3;

FIG. 5 is a broken transverse section of a portion of the burner configuration;

FIG. 6 is a horizontal fragmentary section of ducting associated with the oven at the line 6--6 in FIG. I; and 9 FIG. 7 is a simplified transverse section of a modification of the basic oven form.

Referring now to the drawings in detail, reference numeral 10 designates generally the oven cavity which is approximately cubical and open at the front where a suitable door as indicated by the phantom outline 11 will be provided for closure or completion of the cooking cavity. This cavity is defined by a liner having a top wall 12, opposed sidewalls l3 and 14, bottom wall 15 and rear wall 16, with the bottom advantageously being flat or smooth.

An outer wrapper l7 surrounds the top, sides and bottom of the oven liner in spaced relation over substantially the full depth of the same and is closed at the front and rear to form with the liner a circulation chamber 18 about the latter for a purpose to be described. The top wall 12 of the liner has a centered longitudinal opening 19 at the sides of which the edges are perforated and flanged upwardly to the wrapper 17, with these flanges 20 having multiple perforations for free communication between the space immediately above the cavity opening,l9 and the wrapper-defined chamber 18. Within the noted space between the perforated flanges 20, there is a flanged channel applied to the interior of the wrapper to form a first collector duct 21 which extends fully over the length of the top opening 19 and to the rear approximately to the plane of the. rear wall of the liner. This duct has multiple side wall perforations 22 and is open at the rear end, while being otherwise closed.

Asecond collector duct 23 is provided within the bottom with these connections providing communication between the two ducts and the interior of the manifold. The connection of the top duct 21 to the manifold 25 is controlled by a first damper 26 and a second damper 27 controls the connection of the bottom duct 23. The dampers are operable to close or open the ducts, and the movement thereof is determined by operating levers 28, 29 and a common actuator rod 30, with the levers being differently related to dampers so that the opening of one damper is accompanied by closure of the other and vice versa.

The heat source for the oven cavity is a top burner configuration comprising two elongated blue flame burner devices designated generally by reference numerals 31 and 32, respectively, which extend in close parallel relation'just beneath the top liner opening 19. The burner device 31 includes an air tube 33 which is closed at its forward end by a circular plate 34 and is open at the rear end, within which a support spider 35 providing a considerably smaller axial hub is attached. The air tube 33 has a single longitudinal slot outlet 36 which, with the orientation of the tube as shown in FIG. 3, occurs in the lower outer quadrant of the wall. A burner tube 37 of smaller diameter is supported within the air tube 33 on the spider 35 at the rear and by attachment at the forward end to the plate 34, but eccentrically as most clearly evident from FIG. 5. Such burner tube also has a single row of holes or ports 38, of smaller diameter than the width of the air tube slot 36, and the eccentricity and arrangement of the burner tube within the air tube is such that the burner ports 38 are closely behind such air tube slot 36. The air tube 33 is supported within the cavity at the rear by having the spider 35 engaged about a gas spud 39 and at the front by a bracket or hanger plate 40 and a headed axial pin 41 which is rotatable in the bracket and affixed to the center of the tube end closure plate 34. The burner device 31 can accordingly be rotated for angular adjustment of the burner ports and air tube slot, which remain in the same relation through such adjustment, in a manner to be more fully described below.

The other burner device or section 32 of the burner configuration is of corresponding form, with the like parts of the two having the same reference numerals applied but primed in the section 32, and the burner ports 38' and air slot 36' are again in the lower outer quadrant of the section. The air tube 33' of this further section is supported on a second spud 42 for the gaseous fuel delivery, with the two such spuds supported by the rear wall of the manifold 25 and projecting forwardly therefrom through an isolated supply chamber 43 within the manifold. The chamber 43 is formed by a wall or partition 44 effectively bridging between the front and rear manifold walls and describing the separate chamber of vaulted form as evident in FIG. 2. An opening 45 is provided in such rear wall manifold to the chamber 43, while the rear ends of the air tubes 33, 33' are received in openings in the manifold front wall at the upper portion of such chamber. As also shown in FIG. 2, the width of this separate inner chamber is less than that of the manifold, whereby circulation can be established over the full height of the manifold about the inner chamber. An outlet opening 46 for the manifold is provided in its rear wall below the chamber 43.

A cylindrical shroud 47 is attached to the manifold rear wall to enclose both the inlet opening 45 to the supply chamber 43 and the outlet 46 of the manifold, and a regenerator wheel or drum 48 is supported for rotation within this enclosure. The wheel may be of any heat exchanger type with a multitude of axial flow passages, such as a cylindrical body 49 of spirally wrapped corrugated asbestos impregnated with sodium silicate, this particular device being a known form of regenerative wheel. It is shown in the illustrated oven' embodiment as mounted axially on a shaft 50 for rotation therewith by tined end caps 51 keyed to the shaft and forced into the wheel respectively at its end faces. The shaft 50 extends at the front of the wheel through a heat resistant bearing 52, of carbon for example, and forwardly through the manifold 25 and the rear wall 16 of the oven liner for exposure at the interior of the cooking cavity. At this exposed end, the shaft has a coupler head 53 having a square or other form of socket suitable for driving engagement with the spit of a known oven rotisserie assembly, not shown.

At the rear of the wheel, the shaft 50 extends through vertical ducting comprising an outer air inlet duct 54 and, enclosed therewithin, an exhaust duct 55 of smaller section as shown most clearly in FIG. 6. Bearings 56 and 57 support the shaft where it enters and leaves this vertical ducting, which is applied against the rear of the shroud 47. An electric rotisserie motor 58 drives the shaft 50 by drive chain 59 at a speed of about -10 rpm. and, accordingly, causes the wheel 48 to rotate within the shroud 47.

The exhaust duct 55 has an inlet opening 60 which is coincident with a lower portion of the shroud 47 and hence of the wheel 48, while the inlet duct 54 has openings 61 at the sides of the enclosed exhaust duct 55 which lead to an upper portion of the shroud and wheel. it will be understood that the enclosure of the rotating wheel 48 will be complete except for the openings 45 and 46 at the forward end and the openings 60 and 61 at the rear.

The oven is preferably powered by blower means including a first fan B1 which forces ambient air as indicated by the arrows in FIG. 1 downwardly through the inlet duct 55, the openings 61, the axial passages in the upper portion of the rotating wheel 48, and the opening 45 to the supply chamber 43. Ambient air under pressure is thus delivered to the open ends of the two burner tubes 37, 37' and surrounding air tubes 33, 33' of the burner configuration, with the burner tubes also of course to receive the gaseous fuel under pressure from the spuds 39 and 42. Some of the supply air thus mixes with the fuel in the burner tubes as primary air for combustion, while additional pressurized air flows along the air tube in each section to the ports where the gaseous air-fuel mixture is burned in operation with blue flame. The noted eccentricity of each burner tube relative to the air tube permits the latter to have substantial flow capacity, while providing close spatial relation of the burner ports and the air tube openings where secondary air is substantially directly delivered to the combustion zone. Such closely confined delivery of the secondary air permits the air supply to be at or close to stoichiometric relation to the fuel, and the consequent substantial reduction in the amount of excess secondary air provides significantly more efficient operation and less wasted heat output at the exhaust. Both burner sections of course operate in the same manner and simultaneously, with a suitable ignition system, not shown, provided.

Rectangular shields or baffles 62 and 63 are mounted within the oven cavity respectively at the sides of the burner assembly to extend along the sides of the two sections 31, 32. The inner edges of the shields, the mounting of which is stationary, are in close-spaced relation to the air tubes 33, 33' substantially at the outer center lines of the same, and they extend outwardly at a slight upward inclination over more than a half of the distance to each oven side wall from the burner configuration. As earlier noted, the burner sections 31, 32 are rotatably adjustable on their axes, and such adjustment is provided by pins 64, 64' affixed to the air tube forward end plates 34, 34' at corresponding off-center points and projecting through arcuate slots in the hanger 40 to accommodate turning thereof. This turning or twisting is controlled by a cam plate 65 having curved slots 66 through which pins 64, 64 extend and a vertical actuator rod 67 which extends reciprocably upwardly through the liner top wall 12 and wrapper 17 for exterior accessibility. The arrangement of the burner sections illustrated in H6. 3 is used as one condition of adjustment wherein each section provides a line of blue flame directed downwardly and outwardly respectively from the center and below the shields 62, 63, for example, at an angle on the order of about 25 from horizontal. By pushing the rod 67 and hence cam plate 65 downwardly, the burner sections 31, 32 will be caused to rotate in unison to elevate their ports to a second condition of angular adjustment in which the flame at each side is now directed upwardly and outwardly to approximately the same degree and hence above the shield at that side. In this condition, then, the shields conceal the flame from the main interior of the oven cavity.

The exposed flame condition is of course that utilized for broiling and like operations in the normal use of the oven, and the dampers 26 and 27 will be adjusted in this condition to open the top collector duct 21 and close the bottom collector duct 23. Such damper condition is illustrated in FIG. 1, and it will be seen that the flue products from the burner sections in operation of the oven will proceed over the undersides of the shields 62, 63 to flow about the outer edges of the same, through the top liner opening 19, and into the top duct 21. From the latter, the products proceed through the manifold 25 to the outlet 46, through the axial passages in the lower portion of the rotating regenerator wheel 48, and the opening to the vertical exhaust duct 55. A second fan B2 of the blower means is arranged as shown to apply suction to this exhaust duct to assist in such outflow of the flue products.

The second condition of adjustment of the burner configuration, wherein the blue flame is concealed by the shields, is accompanied by reversal of the damper arrangement for clo sure of the top duct 21 and opening of the bottom collector duct 23. The heated products from the burner assembly, accordingly, in this condition must proceed from the upper space about the now closed top duct to the wrapper chamber 18 and hence about the liner periphery to the bottom collection area where they enter the duct 23. The products proceed from the latter to the manifold 25 and through the lower portion of the rotating regenerator wheel 48 and exhaust duct 55 in the manner previously described in the first condition of operation of the oven. This second condition of flow about the walls of the liner is employed in carrying out baking and other like operations, with the surfaces heated primarily by convection and the articles of food and the like protected, as noted earlier, from the radiant effect of the burner configuration.

In the modified oven 10a illustrated in simplified form in FIG. 7, the same burner assembly 31a is used and the broil condition of operation will be the same utilizing a top collector duct 210. However, in the bake condition, the heated products are caused to sweep over the liner walls within the cavity to an elongated bottom central outlet 68, protected by a suitable shield 69 as shown, which provides the only communication to the bottom collector duct 23a. The adjustment of the burner configuration and the regenerative exhaust system will also be the same as in the first described construction, but here the outer wrapper has of course been eliminated. It may be preferable in this modification to employ a slightly different form of baffle or shield to enhance such interior flow, and burner shields 70 are illustrated as being substantially horizontal and having downwardly curved outer edges for more directive control of the flow from the burner area.

The regenerator wheel 48 and the blower means B1, B2 will be operative in all use of the oven and appropriate interlocking can be incorporated to ensure that this condition is the normal range for cooking and into the range of incineration of the food soils which normally accumulate on the interior surfaces of the oven in the course of usual cooking operations. Such incineration can occur at a temperature of about 750F., with still higher temperatures preferred for more efficient self-cleaning action, such as 950F., and the upper limit is as a practical matter established by insulation and component limits.

In the oven construction disclosed, it is preferred that such self-cleaning cycle be carried out with the burner configuration in the broil condition of adjustment, but with the top collector duct 21 closed and the bottom duct 23 open. This third condition, accordingly, utilizes both the radiant and convective heating effects, with the former of particular benefit as directed primarily to the bottom of the oven where the greatestaccumulation of soil generally occurs and with the liner surfaces heated by the sweep of the burner products substantially fully over the periphery of the cavity, either interiorly or exteriorly of the same. V

The burner shields can effectively contribute to the radiant heating effect by being made of or coated at their undersides with a material which will be readily heated to incandescence by the blue flame or by mounting fine wire screens on the baffles similarly to become incandescent. While the use of two circulating fans is preferred, it is possible that the oven could be suitably sealed and powered with a single fan, at either the inlet or outlet, providing the necessary pressure differential in the direction of the exhaust. The basic oven construction can of course be incorporated in any suitable range or other environment, with appropriate insulation and controls as required or desired.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims or the equivalent of such be employed.

lclaim:

1. in an oven comprising walls forming a cooking cavity, gas-fired burner means within the upper portion of the cavity and having an outlet section at which flame occurs in the operation of the burner means, means for supplying a combustible gaseous mixture to the burner means for combustion at the outlet section thereof, fixed shield means in the cavity having a portion proximate to the outlet section of said burner means and extending an appreciable distance laterally therefrom, means for adjustably mounting the burner means to vary the position of said outlet section, with the flame at the outlet section in a broil position of adjustment being directed beneath the shield means for exposure thereto of food placed in the cavity, and the flame in a bake position of adjustment being directed above the shield means for shielding food in the cavity from radiant heat effect thereof, and means for exhausting the cavity.

2. An oven as set forth in claim 1, wherein the means for exhausting the cavity is selectively adjustable to withdraw the heated products either substantially directly from the upper portion or from a remote location after the products have circulated over the cavity walls.

chamber exteriorly about the cavity walls.

An oven as set forth In claim 3, wherein the heated products when exhausted from said remote location are caused to flow thereto through the cavity.

6. An oven as set forth in claim 1, wherein the burner means comprises first and second sections having elongated outlets, the shield means includes first and second shields respectively associated with said elongated outlets, and said sections are rotated in the adjustment of the burner means to vary the outlet positioning relative to the shield means.

7. An oven as set forth in claim 1, wherein the burner means comprises a burner tube to which the gaseous mixture is supplied having a row of ports as the outlet section thereof, and a secondary air tube encloses said burner tube and has an air outlet in approximate spaced register with the ports of the burner tube.

8. An oven as set forth in claim 7, wherein the burner tube is so disposed within the secondary air tube that the spacing of the two is non-uniform and closest at the outlet section of the former.

9. An oven as set forth in claim 1, wherein the burner means comprises first and second sections, each section including a burner tube having a row of ports as the outlet section thereof, and a secondary air tube spaced about each burner tube with an outlet in approximate register with the ports thereof.

10. An oven as set forth in claim 9, wherein the shield means comprises first and second shields respectively associated with the first and second sections of the burner means, and the means for adjustably mounting the burner means provides rotation of the burner sections to variably direct the flame thereof.

11. A gas oven comprising liner means forming a cooking cavity, means'in the cavity for supporting articles of food to be cooked therein, burner means within the cavity, and circulation means for supplying ambient air to the burner means and exhausting the heated products thereof from the cavity, said circulation means including exterior rotary heat exchanger means through successive portions of which the heated products and ambient air are directed for preheating of the latter by the former, and a motor-driven shaft on which said heat exchanger means is mounted to be rotated thereby, with said shaft extending through the liner means, and coupling means on the shaft within the cavity to provide a rotary power connection therein.

12. in an oven comprising walls forming a cooking cavity, gas-fired burner means in the upper portion of the oven for both broiling in said cavity and for baking therein, means for supplying a combustible gaseous mixture to said burner means for combustion at the outlet section of the same, first exhaust means for withdrawing the combustion products of the burner means substantially directly from the region of the latter to the exterior of the cavity, second exhaust means for withdrawing such products from the bottom portion of the cavity after circulation through the same, means for selectively operating the first and second exhaust means respectively for broiling and baking in the cavity, and means for selectively exposing and shielding food placed within the cavity to and from the burner flame respectively for such broiling and baking.

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