MXPA96003576A - Oven of waves of light that have interior arists in face - Google Patents

Abstract

It has been found that significant improvements in the efficiency of an oven can be made by constructing a light-wave oven that eliminates or minimizes the number of right angled edges formed between the walls of the oven. In an exemplary embodiment, the removal of these edges is carried out by spreading strips of highly reflective material between the adjacent wall sections to form beveled or faceted regions instead of square corners. Furnace efficiency is further increased using a highly reflective wall material such as Alanod aluminum that is at least 88-90 percent reflective over the portion of the electromagnetic spectrum in which the lamps emit radiation (approximately 0.4æm to 4.5æm). The most representative figure of the invention is the number

Description

OVEN OF WAVES OF LIGHT THAT HAS INTERIOR ARISTS IN FACETS Field of the Invention This invention relates in general to the field of radiant source furnaces and in particular to the field of furnaces that use visible, almost visible and infrared radiant energy sources for culinary applications. BACKGROUND OF THE INVENTION Light cooking wave ovens following the present invention and having linear sources of visible, near visible and infrared radiant energy are presented and described in U.S. Patent No. 5,036,179 and in US Pat. International Application Number PCT / US94 / 05753 which was published under International Publication Number WO 94/28692, each of which is incorporated herein by reference. The light wave furnaces may use a plurality of lamps, such as quartz-halogen tungsten lamps or equivalent lamps as quartz arc lamps, or an arrangement of several lamps either operated in unison or selectively operated in varying combinations as necessary for the particular food item that you want to cook. Generally, typical quartz-halogen lamps of this type can be provided with between 100 and 2 W of radiant energy with a significant portion of the energy in the visible light spectrum. Each lamp typically operates at 3000 degrees Kelvin and converts electrical energy into blackbody radiation having a wavelength range from about 0.4 μm to 4.5 μm with a maximum intensity at 0.965 μm. These ovens provide cooking for high speed cooking or baking, with high quality for food items by striking visible, almost visible, and infrared high intensity radiations on a food item. The ovens cook the food items within short periods of time normally found in microwave cooking while maintaining the browning of the infrared cooking and the cooking quality by conduction-convection. When the food is exposed to a sufficiently intense source of visible, almost visible, and infrared radiation, the food absorbs low levels of visible and almost visible radiation, thereby allowing the energy to penetrate the food's filling and warm it deeply. The longer infrared radiation does not penetrate deeply but acts as an effective gilding agent. These radiation sources are ordinarily placed above and below the food item. The lamps are typically placed behind transparent radiation plates mounted inside the oven. These plates can be formed of materials, such as high-quality and heat-resistant materials such as glass and pyroceramics that are transparent to visible, almost visible and infrared radiation. The walls of the chamber surrounding the food preferably are made of highly reflective surfaces. The visible and infrared waves from the radiation sources collide directly on the food article and are also reflected on the reflecting surfaces and on the food article from many angles. This reflective action improves the uniformity of cooking. However, the corner and corner regions within the furnace may form areas of increased absorption due to multiple bounces of the reflections. It has been found that, because the materials of the surface of the oven wall are not 100% reflective on the portion of the electromagnetic spectrum within which cooking by light waves is preferably achieved, a portion of the radiant energy is absorbed by the surfaces inside the furnace on which radiant energy bounces. For example, suppose that a furnace cavity has a wall surface that has a reflectance of 80 percent. Eighty percent of the energy hitting the surface of the wall at any given moment is reflected out of the surface, while 20 percent of the energy is absorbed by the surface. In this way, each time an element of radiant energy hits the surface of the wall, it loses 20 percent of its energy. If that element of energy hits the surface of the wall several times, it will lose 20 percent of its remaining energy with each rebound. The energy that remains once the energy element reaches the food decreases significantly by this. Because a square corner of the oven is formed of three surfaces joined together, there are more opportunities for the radiant energy elements to reach the corners to bounce many times before being reflected in a direction with which they reach the food in the oven. Therefore, significant amounts of the total energy produced by the lamps can be lost, leading to a decrease in the efficiency of the oven. It is therefore desirable to configure a light wave oven which minimizes losses of this nature to improve the overall efficiency of the furnace. SUMMARY OF THE INVENTION It has been found that significant improvements can be made to the efficiency of an oven by constructing a light wave oven that eliminates or minimizes the number of edges at right angles formed between the walls of the oven. In an exemplary embodiment, the removal of these edges is carried out by spreading strips of highly reflective material between the adjacent wall sections to form beveled or faceted regions instead of square corners. Furnace efficiency is further increased using a highly reflective wall material such as Alanod aluminum that is at least 88-90 percent reflective over the portion of the electromagnetic spectrum in which the lamps emit radiation (approximately 0.4 μm to 4.5 μm). Description of the Drawings Figure 1 is a front elevated view of an oven according to the present invention, in which, for purposes of clarity, the door is not shown. Figure 2 is an exploded view of the housing of an oven according to the present invention, showing the inner housing, the outer housing, and the control board. Figure 3 is an exploded view of the internal housing of an oven according to the present invention. Figure 4 is a cross-sectional plan view of an oven according to the present invention, taken along the plane designated 4-4 in Figure 1 and showing the bottom wall of the oven cavity. Figure 5 is a cross-sectional plan view of an oven according to the present invention, taken along the plane designated 5-5 in Figure 1 and showing the upper wall of the oven cavity. Figure 6 is a cross-sectional side view of an oven according to the present invention taken along the plane designated 6-6 in Figure 1. Figure 7 is a top plan view showing the grate, the pulley guide, the drive pulley, and the horizontal rotary bearing. Figure 8A is an exploded view showing the components of the rotation mechanism of the grate. Figure 8B is a side elevational view of the horizontal rotary bearing. Figure 9 is an exploded view of the arrangement of pulleys used to rotate the grate. Figure 10 is a side view of the pulley of the pulley arrangement of Figure 9. Figure 11 is a side sectional view of the first side of the pulley and the arrow of the pulley. Figure 12 is a view of the side section of the second side of the pulley. Figure 13 is a side sectional view of a guide pulley roller. DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1, the present invention is generally comprised of an oven 10 having an interior cavity 12, a rotary circular spit 14 mounted within the cavity, and radiant energy sources, or lamps 16a - 16d, 18a-18c (see also Figures 4 and 5) mounted above and below the grate. The energy for cooking is supplied by the upper and lower lamps 16a - 16d, 18a - 18c. The lamps are preferably quartz-halogen tungsten lamps that are capable of producing between approximately 100 and 2 k radiant energy with a significant portion of the light energy in the visible and almost visible range of the light spectrum. When illuminated, the illuminated portion of a preferred lamp has a length of about 25.4 centimeters. Referring to Figure 2, the furnace 10 is formed by an internal housing 20 which is mounted within an external housing 22. The outer housing 22 includes a substantially horizontal base 24, a frame that includes the side walls 26a, 26b which extend vertically from the base 24 and support members 28 which extend between the walls 26. A rear wall plate 30 extends between the walls 26 and extends vertically from the base 24. An exhaust opening 32 is centered in the rear wall plate 30, and an exhaust pipe 34 extends from the opening 32 to draw hot air from the lamp arrays and from the furnace cavity. The operation and control of the furnace (and thus the lighting of the lamps) is carried out using a control board 36 located on the front part of the furnace 10. The control board 36 is electrically and electronically coupled to the furnace circuits, which include a processor, a control circuit, and power components and circuits collectively designated 38 in Figure 2. The control board 36 and circuit 38 are attached to the control board housing 40 which includes a front wall 42, a base wall 44, and a side wall 46 and which is mounted to the base plate 24 so that the side wall 46 is adjacent the side wall 26b. A cover 48 is attached to the base 24 and, with the wall 30 and the base 24 surrounds the oven 10. A faceplate 49 (Figure 1) having a rectangular opening leading to the oven chamber is mounted on the front of the oven. The furnace and a door 62 (see Figure 3) is hinged to the faceplate 49. The inner housing 20 is mounted within the outer housing 22. Referring to Figures 2 and 3, the inner housing 20 includes a bottom plate 50 and a pair of side walls 52 extending vertically from the bottom plate 50. A rectangular opening 51 is formed in the bottom plate 50.

Each side wall 52 is comprised of a substantially vertical wall portion 54 and, at the top, an angled portion 56 extending into the interior of the furnace. In one embodiment, the angled portion 56 has an angle of about 45 ° downward from the vertical plane occupied by the vertical wall portion 54. The triangular metal tabs 58 extend outwardly from the angled portions 56, so that when the inner housing 20 fits within the outer housing, the tabs 58 lie parallel to the front face 49 of the oven. The angled portions 56 of the side walls 52 create, in combination with the upper panel 66 and the vertical portions 54 of the side walls 52, faceted edges for the interior surface of the oven. Each "facet" is composed of three surfaces, each of which forms an angle of approximately 135 ° with its neighboring surface (s). It is believed that these facets improve oven efficiency as much as 8 percent or more by (1) decreasing the total surface area of the kiln; and (2) allow portions of the radiant energy, which would otherwise be lost through many "bounces" in the corner regions, to redirect towards the position of the food with fewer bounces or, in many cases, with a single bounce. An added benefit of the facets is that they are easier to clean than cubic corners.

Many alternative forms of furnace or facet configurations that direct reflected light to the position of the food can be conceived. For example, all corners and edges within the furnace may be beveled, or the furnace may have a spherical or cylindrical shape or many small facets may be formed on the furnace walls. Referring again to Figures 2 and 3, the rear wall 60 of the furnace chamber extends vertically from the lower plate 50 of the chamber. The door 62 is hinged on the front face 49 and has a closed position in which it covers the opening in the front of the oven and an open position in which the opening is exposed for the placement of the food in, or to remove the food, from inside the oven. A window 64 of pyroceramic material can be formed in the door. An upper panel 66 extends between the angled portions 56 of the side walls 52. The upper panel 66 does not extend along the entire length of the front to the back of the side walls 52, but there is a large opening 68 ( Figure 2) between the front panel 66 and the rear wall 60 of the inner chamber. An upper reflector housing 70, and a lower reflector housing 72 are mounted inside the furnace (see, for example, Figure 1). Each has an inward side that is formed by Alanod aluminum that has a mirror surface and has a reflectance of at least about 88-90 percent. The upper reflector housing 70 is positioned so that its inward side is positioned to face down on the opening 68 in the upper part of the inner housing 12, while the lower reflector housing 72 is positioned so that its side inwards it faces upwards through the opening 51 in the lower plate 50. The vents 74 are formed on the front and rear sides of the reflector housings 70, 72 to allow the escape of the hot air. A plenum 75 extends from the vents 74 in the upper and lower reflector housings 70, 72 to direct the heated air of the vents 74 towards the exhaust pipe 34. The laterally placed sides of the reflector housings 70, 72 include the slots 76, 78, respectively, through which the ends of the lamps 16a-16d, 18a-18c extend (Figure 1). Lamps 16a-I6d, 18a-18c are mounted inside the furnace to receive energy in a conventional manner. Two radiation-transparent plates 80 and 82 are mounted inside the furnace. These plates isolate the firing chamber of the radiant lamps, making the oven easier to clean. These plates can be formed of materials, such as heat resistant glass and high quality pyroceramic materials, which are transparent to visible, invisible and infrared radiation. The upper transparent plate 80 is placed below the upper lamps 16a-16d so as to cover the opening 68 (Figure 2) in the upper part of the inner housing 20 and, in effect, enclose the lamps 16a-16d inside the reflector housing 70. The lower transparent plate 82 is placed on top of the lower lamps 18a-18c so as to cover the opening 51 in the lower plate 50 in the lower part of the inner housing and, in effect, enclose the lamps 18a-18c inside the housing Reflector 72. Because the pyroceramic material absorbs the radiation emitted by the lamps and reflects it into the furnace, it is desirable to minimize the total area of the pyroceramic material to maximize the efficiency of the furnace. By minimizing the area of the pyroceramic material, the area of reflection surfaces that can be formed in the furnace is maximized, and this allows a greater portion of the radiation to be reflected from the more highly reflective reflector and the wall material instead. of being absorbed by the pyroceramic plates. Less absorbent window materials can be used to improve oven efficiency. Each pyroceramic plate has approximately 25.4 centimeters by 35.05 centimeters in size (the upper and lower walls 210, 211 are squares of approximately 45.7 centimeters on each side). This is a fairly significant reduction compared to, for example, the FB-3000 light wave manufactured by Quadlux, Inc. in Fremont, CA, which uses top and bottom pyroceramic plates of approximately 35.05 centimeters by 35.05 centimeters. The inner surfaces of the inner housing 20 preferably have highly reflective surfaces. The walls 52 and 60, the top panel 66, and the door 62 preferably have interior surfaces of a highly reflective material, such as highly polished Alanod aluminum (in mirror), which at least is approximately 88-90 percent reflective on the portion of the electromagnetic spectrum in which the lamps emit radiation (approximately 0.4 μm to 4.5 μm). The bottom plate 50 has an interior surface of polished anodized aluminum. In the embodiment shown of the present invention, the inner housing 20 has a vertical inner height of 18.75 centimeters (i.e., measuring from the upper panel 66 to the lower plate 50). The height of the vertical wall portion 54 is 13.35 centimeters and the angled portion is approximately 7.72 centimeters from the top of the vertical portion 54 to its upper edge. Referring to Figure 6, a thermistor 31 is placed within plenum 75 between the rear wall plate 30 of the outer housing 22 and the rear wall 60 of the internal housing 20. The thermistor 31 detects changes in the oven temperature caused by successive cooking operations. Preferably, the thermistor 31 is placed approximately 2.54 centimeters from the rear surface of the rear wall 60 and is preferably centered between the walls 54 (which are at a distance of 45.72 centimeters). The height positioning of the thermistor is approximately 9.4 centimeters above the horizontal plane in which the lower plate 50 is placed. This place was chosen so that the temperature rise time of the oven measured by the thermistor coincides with the rise time of the increase in the temperature of a water dish (simulating food) placed in the oven and heated only by the accumulation of heat in the oven. Figures 4 and 5 show the positions of the lamps used in the preferred furnace according to the present invention. In the preferred mode, there are four upper lamps from 16a to 16d and 3 lower lamps from 18a to 18c. By properly selecting the lateral space between the lamps in relation to the food, even cooking over the entire surface can be achieved. This is achieved by rotating the food article using a rotary spit 14 and arranging the lamps so that during the cooking cycle all regions of the food surface receive equivalent amounts of energy from the lamps. This desired result is more easily achieved by placing the lamps asymmetrically with respect to the median line m of the horizontal cooking area (i.e., the midpoint between the front F and the rear part B of the oven cavity). The asymmetrical configurations of the lamps can be selectively illuminated depending on the size of the article of food that is sought to be baked and its ability to absorb visible light. Because different types of food are capable of absorbing different amounts of energy, such a configuration would be particularly useful when, for example, a saucer containing different foods for cooking is placed on the grill. An example of the asymmetric separation of the lamps is shown in Figures 4, 5 and 6. In the embodiment shown of the furnace of the present invention, the front F and the rear part B of the furnace cavity are separated by a distance of 45.72 centimeters. The axis of rotation X (Figure 6) of the grill 14 is midway between the front and rear walls (i.e., 22.86 inches from the front wall and the rear wall). The upper lamps 16a-16d are positioned at 24.13 centimeters, 34.29 centimeters, 36.83 centimeters, and 39.37 centimeters from the front F of the cavity, respectively. The lower lamps 18a-18c are positioned at 21.59 centimeters, 35.56 centimeters, and 38.1 centimeters from the front F of the cavity, respectively. Naturally, many asymmetrical configurations of the lamps are possible which will provide uniform cooking of the food placed on the grill 14. Also, it should be noted that the positions of the lamps given above can be varied more or less 0.32 centimeters (or, in some cases, even more variation is acceptable) at the same time that substantially uniform radiation is maintained through the placement of the food. The circular grill 14 is composed of a grid of small diameter metal bars 33. During use, a heat-resistant glass or pyroceramic dish or a metal baking mold that holds the food on the grill for cooking is placed. The grate has a diameter of preferably 40.64 centimeters and is capable of rotating about an axis of rotation, designated X. The mechanism for rotating the grate 14 is shown in Figures 7-13. The grate 14 and the motorized mechanism for rotating the grate 14 will be described below. The grate 14 (Figure 7) is preferably formed by a circular metal ring 136 and a plurality of parallel cross bars 137 secured at their ends to the ring 136. The ring 136 has a uniform circular cross section. Referring to Figure 8A, an arrangement of pulleys 172 is provided which is secured to the wall 26 (Figure 2) of the furnace by its support member 166. A pulley 162 extends from the support member 166. In the Figure 8A shows an exploded view of the arrangement of pulleys 172. The arrangement of pulleys 172 is comprised of a grip roller type pulley 162 having an arrow 174 that extends through, and is rotatable within, the support member 166 The arrow 174 (see Figure 9) in turn is coupled to a motor 120 (Figure 8A) so that the pulley 162 is at the first end 173 of the arrow 174 and the motor 120 is at the second end 175. In this way, the rotation of the arrow 174 by the motor produces the corresponding rotation of the pulley 162. The motor is mounted outside the cooking cavity in a cold place as behind the control board 36. Referring to Figure 9 , the pulley is composed of a first side d e pulley 180 and a second pulley side 182. The first pulley side 180, shown separately in Figure 11, is preferably welded to the first end 173 of the arrow 174. It has a mating surface 184 that is angled away of the arrow by an angle Al, measured from a plane perpendicular to the longitudinal axis of the arrow 174. In the preferred embodiment, the angle Al is preferably 7-8o. The second pulley side 182 is shown in cross section in Figure 10. It is composed of a first tubular end 190 and a second tubular end 192 that is longer than the first tubular end 190. An orifice 186 provided to receive the arrow 174 extends longitudinally through the side of the pulley 182. A wheel portion 194 is positioned between the tubular ends 190, 192. The wheel portion 194 has a mating surface 188 surrounding the orifice 186. The mating surface 188 is remote at an angle from a plane perpendicular to the longitudinal axis of the hole 186 at an angle A2, which is preferably 7-8o. The pulley sides 180, 182 are accommodated by passing the arrow 174 through the traversed hole 186 on the side of the pulley 182. The sides 180, 182 are secured in the assembled condition by conventional means, such as by a pin (not shown) extending through a first hole 181 in the arrow 174 and through a second hole 183 in the tubular portion 190 of the second side of the pulley 182. When the arrangement of pulleys 172 is assembled, the angled surfaces 184, 188 are separated at an angle to each other as shown, and the long tubular portion 192 of the pulley side 182 extends between the two sides of the pulley 180. , 182. A slot 198 having a U-shaped cross section is thus formed between the pulley sides 180, 182. The slot 198 is provided to partially receive the ring 136 from the grill 14 and to impart rotational force to the ring 136 when the pulley arrangement 172 is rotated. The slot 198 should be provided for the ring to contact both sides of the pulley 180, 182 to ensure that the rotational force is imparted to the ring 136. In the preferred embodiment the inner perimeter of the ring 136 makes contact with the pulley side 180 at two points and the outer perimeter of the ring 136 makes contact with the pulley side 182 at a point. In the preferred embodiment, the ring 136 has a cross section of 0.64 centimeters in diameter. The preferred pulley arrangement 172 is machined accurately so that the pulley sides 180, 182 are separated by a distance of 0.66 centimeters at their outermost edges and so that the tubular portion 192 is separated from the pulley side 180 by a distance of 0.0254 centimeters. To withstand the enormous heat generated inside the oven during cooking, the pulley arrangement is preferably made of hardened stainless steel that has been heat treated to Rockwell "C" 40 or harder. Referring again to Figures 7 and 8A, the drive rolls 168 are secured by support members 170 to the floor of the furnace cavity. A drive roller 168, shown in cross section in Figure 13, is comprised of a wheel portion 298, a first end portion 100, and a second end portion 102. A through hole 104 runs longitudinally through the roller 168 and The pin portion 298 is angled away from the end portion 100 at an angle A3 that is preferably 35 ° plus or minus 2 ° from a plane perpendicular to the longitudinal axis of the through hole 104. Referring to FIG. to Figure 8A, each drive roller 168 is mounted on its respective support member 170 by a bolt 106, with the end portion 100 of the roller 168 extending radially towards the center of the grate (which is not shown in Figure 8A). During operation, the grill 14 (Figure 9) is positioned so that its perimeter 136 is supported by the drive rollers 168 at their respective end portions 100 and by the pulley 162. Each roller 168 must be engaged with its respective support member 170 so as to allow it to rotate freely in response to the rotation of the grate 14. The pulley 162 and the rollers 68 are preferably separated from each other by approximately 120 ° to provide balanced support for the grate 14. A brass bearing 220 (Figure 8B) is mounted horizontally to the base wall 50 (Figure 2) to press lightly against the ring 136. Due to the large size of the grill and therefore its relatively large mass, it could be difficult for the grill to balance and rotate, the bearing 220 helps to keep the grill properly aligned with the pulley and rollers. The bearing 220 rotates on an arrow 222 which is supported by an aluminum block 224 mounted on the lower wall 50 of the furnace chamber. During use of the oven the grill 14 is positioned so that the ring 136 sits on the pulley 162 and the rollers 168. The pulley 162 rotates when the motor 164 is activated thereby causing the rotation of the grate 14. The rotation is facilitated by the rolls 168 that roll as a response to the movement of the grill 14. This rotation of the grill 14, and therefore of the food placed on the grill, increases the uniformity of the cooking avoiding that the radiant energy of the lamps for cooking in the Oven (not shown) will focus on any specific region of the food item. The present invention is described in relation to the preferred embodiment but is limited only in terms of the language of the appended claims.

Claims (1)

NOVELTY OF THE INVENTION Having described the foregoing invention, it is considered as a novelty and, therefore, the content of the following is claimed as property. CLAIMS

1. A light wave oven comprising: a housing having a reflective interior surface; a food support mounted inside the housing; a radiant energy source positioned within the housing and oriented to direct radiant energy on the food support; and facets formed on the reflecting interior surface, faceted to reflect at least a portion of the radiant energy emitted by the lamps towards the food support.