Classifications

• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B6/00—Heating by electric, magnetic or electromagnetic fields
  • H05B6/64—Heating using microwaves
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/40—Heating elements having the shape of rods or tubes
  • H05B3/42—Heating elements having the shape of rods or tubes non-flexible
  • H05B3/44—Heating elements having the shape of rods or tubes non-flexible heating conductor arranged within rods or tubes of insulating material
• • H—ELECTRICITY
  • H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
  • H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
  • H05B3/00—Ohmic-resistance heating
  • H05B3/0033—Heating devices using lamps
  • H05B3/0071—Heating devices using lamps for domestic applications
  • H05B3/0076—Heating devices using lamps for domestic applications for cooking, e.g. in ovens

Definitions

• This invention relates to the field of radiant source ovens. More particularly, this invention relates to ovens having a rotating rack and an array of linear radiation sources typically shorter than the transverse dimension of the cooking location and which are arranged to maximize uniform cooking of a food item.
• Ovens following the present invention and having linear sources of visible and infra-red radiant energy are disclosed and described in U.S. Patent No. 5,036,179 and U.S. Patent Application Serial No. 07/738,207 which are incorporated herein by reference.
• These ovens provide high-speed, high-quality cooking and baking of food items by impinging high-intensity visible, near-visible, and infrared radiations onto a food item.
• the ovens cook the food items within the short periods of time normally found in microwave cooking while maintaining the browning of infrared cooking and the quality of conduction-convection cooking.
• the source of the visible, near- visible and infrared radiation for this invention is in excess of two elongated quartz-halogen tungsten lamps, or equivalent means such as quartz arc lamps.
• Typical quartz-halogen lamps of this type operate at 3000 degrees Kelvin and convert electrical energy into black body radiation having a range of wavelengths from .4 ⁇ m to 4.5 ⁇ m with a peak intensity at .965 ⁇ m.
• Each lamp can generally provide about between 1.5 and 2 kW of radiant energy with a significant portion of the energy in the visible light spectrum.
• the ovens can use a plurality of these lamps or an array of several lamps either operated in unison or selectively operated in varying combinations as necessary for the particular food item sought to be cooked.
• These radiation sources are ordinarily positioned above and below the food item.
• the walls of the surrounding food chamber are preferably made from highly reflective surfaces.
• the visible and infrared waves from the radiation sources impinge directly on the food item and are also reflected off the reflected surfaces and onto the food item from many angles. This reflecting action improves uniformity of cooking.
• the intensity of radiant energy received by an object decreases with the increase in distance between the object and the radiant energy source.
• the reflective interior surfaces of the oven the areas of the food item that are positioned directly above or below the radiation sources receive more direct energy and therefore cook more quickly than their surrounding areas.
• Figures 1A and IB show an end view and a longitudinal side view, respectively, of a single linear radiation source 100 and further show the distributions of light intensity measured at the surface of a food item positioned underneath the radiation source. As shown in both figures, the regions of the food item which are positioned directly below the light source are exposed to the maximum intensity received by the food item, while the surrounding areas are exposed to significantly lower intensities.
• Figure 2A shows a lamp configuration under which a food item 104 is cooked under an array of elongate radiation sources 100 that are shorter than the length of the food item and that are arranged in parallel. The food item is cooked to the desired degree in the regions of the food item that are close to the lamps, designated by shading in Figure 2B. The unshaded regions remain uncooked or undercooked.
• FIG. 3A shows a circular food surface 104, such as a pizza, positioned underneath a single radiation source 100a having a length 1.
• the radiation source is parallel to and shorter than diameter d of the pizza.
• FIG 3B when the pizza is rotated about its center C, the radiation source cooks a circular region AA having diameter equal to the length 1 of the radiation source 100a.
• cooked portion AA is itself non-uniformly cooked: the regions that are closer to the center C spend more time under the radiation source and therefore are cooked more thoroughly than those regions that are further away from it.
• Figure 5A shows five equally spaced radiation sources 100c, lOOd, lOOe fixed over a pizza 104 which is positioned on a rotating rack (not shown) .
• the sources are equal in length, and their length 1 is less than the diameter d of the pizza 104.
• the center source 100c lies above the diameter of the pizza, and the outer radiation sources are positioned parallel to it.
• the present invention utilizes an array of light sources asymmetrically placed with respect to the diameter of a rotating rack.
• the lamps have a length that is shorter than the width or diameter of a cooking area. Rotation of a food item beneath the asymmetrically placed lamps causes substantially all of the food surface to be exposed to substantially the same radiation for a substantially equal period of time and therefore results in substantially uniform cooking of the food item.
• Figures 1A and IB are an end view and a side view, respectively, of a lamp and with its associated intensity distribution measured at the surface of a food item positioned underneath the lamp.
• Figures 2A through 5B are schematic representations showing four different lamp arrays and the regions of a food item that are cooked by each of the respective arrays.
• Figure 6 is a front section view of an oven according to the present invention.
• Figure 7 is a side section view of a preferred embodiment of an oven according to the present invention.
• Figures 8A, 8B, and 8C are a perspective view, a top plan view, and a side elevational view, respectively, showing the preferred means for rotating the rack of the present invention.
• Figure 9 is a schematic representation of the preferred lamp configuration according to the present invention.
• the present invention is comprised generally of an oven 10, a rotating circular rack 31, and upper and lower arrays 18, 16 of radiant energy sources, or lamps.
• Figure 6 is a front section view of the oven.
• the energy for cooking is supplied by lower heating lamps
• the lamps are preferably quartz-halogen tungsten lamps which are capable of producing approximately 2 kW of radiant energy with a significant portion of the light energy in the visible light spectrum.
• the lighted portion of a preferred lamp has a length of approximately 10 inches.
• the inner surface of the inner wall 12 is preferably a highly polished metal, such as aluminum or stainless steel, which is very reflective to the wide spectrum of wavelengths from the radiant lamps.
• the oven has a door 40 ( Figure 7) which also has a reflective inner surface.
• Two radiation transparent plates 20 and 24 are used to isolate the cooking chamber from the radiant lamps, making the oven easier to clean. These plates can be formed from materials, such as high quality heat-resistant glasses and ceramics that are transparent to visible, non-visible and infrared radiations.
• the lower transparent plate 20 is supported by brackets 22a and 22b and is positioned above the lower lamps 16.
• the upper transparent plate 24 is supported by brackets 26a and 26b and is positioned below upper lamps 18. Shelf 28 is mounted between the transparent plates inside the oven chamber. As shown in Figure 8A, the shelf 28 has a circular cut out portion 27 which is lined at its perimeter by a track 29.
• a heat-resistant glass dish which holds the food is placed on top of the rack for cooking.
• the rack has a diameter of preferably 12 to 14 inches and is capable of rotating around an axis of rotation, designated r.
• Rollers 35 are positioned such that when one of them is rotated by a motor (not shown) , they engage with the perimeter portion of the rack, causing the rack to rotate within the track 29.
• Figure 7 shows a side section of the preferred oven according to the present invention. In the preferred embodiment, there are 5 lower lamps 16a through 16e and 5 upper lamps 18a though 18e. By appropriately selecting the lateral spacing between the lamps relative to the food, even cooking can be achieved over the entire surface.
• an equal number of equally spaced lamps may be positioned on either side of the midline, and asymmetrical configurations of lamps may be selectively illuminated depending on the size and of the food item sought to be cooked and its ability to absorb visible light. Because different food types will be capable of absorbing different amounts of energy, a configuration of this type would be particularly helpful when, for example, a dish containing various foods is positioned on the rack for cooking.
• FIG. 9 A top view of the preferred lamp array is shown in Figure 9.
• the lamps in the upper and lower arrays are identically arranged. Positioning of the lamps will be described with respect to a midline m which bisects the array and which intersects the axis of rotation r ( Figures 6 and 7) of the rack 31.
• Three of the lamps, 18a, 18b, and 18c, are positioned on one side of the midline and are respectively 5.5 inches, 4.5 inches and 1 inch from the midline.
• the remaining two lamps, 18d, 18e are positioned on the opposite side of the midline and are positioned 3.5 inches and 5.9 inches from the midline, respectively.
• the lamps are positioned approximately 3 inches above the rack 31.
• the lateral positions of the lamps from the midline can be varied plus or minus one-eighth inch from their stated positions while still maintaining substantially uniform radiation across the food location.
• the positions of the lower lamps 16a-16e are the same as the upper lamps 18a-18e but obviously the position of one of these two sets can be reversed with respect to the other.
• the food item sought to be cooked is positioned on the rack 31 and the door 40 is closed.
• the motor is switched on, causing the roller to engage and rotate the rack.
• the lamps are illuminated for a predetermined cooking time, causing the food item to cook uniformly.

Landscapes

• Physics & Mathematics (AREA)
• Electromagnetism (AREA)
• Electric Stoves And Ranges (AREA)
• Baking, Grill, Roasting (AREA)
• Electric Ovens (AREA)
• General Preparation And Processing Of Foods (AREA)
• Vending Machines For Individual Products (AREA)
• Cookers (AREA)

Applications Claiming Priority (3)

Related Child Applications (1)

Publications (2)

Family

ID=22065210

Family Applications (1)

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Family Cites Families (7)

• 1994
  • 1994-05-20 CA CA002163442A patent/CA2163442C/en not_active Expired - Lifetime
  • 1994-05-20 AT AT94917464T patent/ATE260536T1/de not_active IP Right Cessation
  • 1994-05-20 EP EP94917464A patent/EP0699373B1/de not_active Expired - Lifetime
  • 1994-05-20 JP JP50085495A patent/JP3488238B2/ja not_active Expired - Fee Related
  • 1994-05-20 KR KR1019950705190A patent/KR960702725A/ko not_active IP Right Cessation
  • 1994-05-20 DE DE69433574T patent/DE69433574T2/de not_active Expired - Lifetime
  • 1994-05-20 WO PCT/US1994/005753 patent/WO1994028692A1/en active IP Right Grant
  • 1994-05-20 AU AU69177/94A patent/AU682876B2/en not_active Expired

Non-Patent Citations (1)

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