Patent Application
20060049185
Commercial food preparation operations typically involve cooking, drying, and/or browning of items. It is often necessary to apply these processes to large quantities of food articles in the shortest possible time, and this has led to the use of continuous feed microwave ovens of several types.
One such microwave oven makes use of an elongated, single mode microwave energy applicator. The single mode applicator is designed, from an electromagnetic standpoint, to be a waveguide that applies microwave energy in a shape that is optimized depending upon the shape of the product being cooked. For example, if the product being cooked is relatively square in cross-section, the applicator may itself be designed as an elongated, tapered rectangular cavity that is several feet long.
Such an applicator is typically left open on both ends so that food articles to be cooked can travel on a conveyor belt that travels inside the waveguide. With food portion sizes appropriate for heating using an applicator of this design, the product entrance and exit may be constructed using well known techniques to prevent microwave leakage. For example, the entrance and exit openings can be limited in size to be something less than the propagating waveguide dimension, which in turn depends upon the wavelength of the microwave energy. Thus, for microwave applicators designed for operating in the 900 Megahertz (MHz) region, as long as openings are no more than about 6 inches or so in each dimension, energy will be contained.
It is thus known that a continuous feed system can be provided for heating articles passing through an oven cavity with a heating source, such as a microwave energy source. However, when a conveyor belt is used to continuously feed articles through the oven cavity, the belt may be unsupported in the middle of the oven, which causes the belt to dish or become concave. Such a belt configuration causes the food articles traveling through the oven to slide toward one another, causing the articles to stick or become adhered to one another during the heating process.
To solve this problem, the present invention presides one or more dividing mechanisms along a longitudinal axis of the conveyor. The dividing mechanisms keep at least some of the food articles from touching. In one embodiment, one or more O-ring cord dividers can be wrapped around and driven by the conveyor. A guiding device can be used to maintain the dividing mechanism on the belt in a desired position.
In other embodiments, a mold for use with a continuous feed system is provided to form products in which a specific outer contour of the articles is desired. The mold can include cavities having any desired geometrical shape, such as circular, square, triangular, oval, etc. A guiding device can be used to maintain the mold in a desired position with respect to the conveyor.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of various embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
A description of preferred embodiments of the invention follows.
A circularly polarized microwave signal is one in which the polarization vector of the microwave energy continually rotates. Generally, however the system will use a rectangular waveguide with linear polarization.
A second heating source can include a burner or heater that provides hot air to the oven to heat the articles 12 by forced air convection. In other embodiments, the second heating source can include an infrared source or employ other suitable surface heating techniques. In further embodiments, a third heating source can be used to further process the articles 12. The third heating source can include a steam source coupled to the oven through steam vents.
Conveyor belt 14, in one embodiment, is formed from a substantially microwave transparent material. That is, the belt 14 is formed from a material that is substantially electrically non-conductive. In one embodiment, the belt is substantially heat resistant up to about 500 degrees Fahrenheit. That is, the belt can operate in temperatures sufficient to cook the articles 12 without significant degradation. In one embodiment, the belt 14 is formed from material that does not adhere to the cooked articles 12. For example, the belt 14 can be formed from glass fibers that can be woven. The glass fibers can also be mixed or coated with Teflon™ material or other suitable materials.
Because the conveyor belt 14 is unsupported in the middle of the oven, the belt tends to dish or become concave due to gravity. When this happens, it has been found that the food articles 12 traveling through the oven tend to slide toward the middle of the conveyor belt 14 and become adhered to one another as they are processed.
In one embodiment of the present invention, this problem is alleviated by one or more longitudinal dividing mechanisms 16, such as an O-ring cord divider. The dividing mechanism(s) can be used to insure that at least some of the food articles 12 do not touch each other along two or more lanes along the longitudinal axis of the conveyor belt 14.
In a particular embodiment, the dividing mechanism(s) 16 can be formed from a material that has suitable release properties, such as Teflon™ material, so that the food articles 12 do not stick to it. The dividing mechanism(s) 16 should also be formed from a material that is chemically stable, for example, FDA approved, substantially microwave transparent, substantially electrically non-conductive, and temperature resistant, for example, able to withstand temperatures of at least 300 degrees Fahrenheit without significant degradation. In a particular embodiment, the dividing mechanism 16 is formed from silicone rubber.
In this embodiment, the dividing mechanism(s) 16 can be wrapped around and driven by the conveyor belt 14. To keep the dividing mechanism(s) 16 in position, a guiding device that can include one or more guides 18 can be positioned on an arm 20 that is pivotable with respect to table 22. The guide 18 is movable along the arm 20 in a particular embodiment. Guide 18 includes a slot through which the dividing mechanism 16 is fed so as to maintain the dividing mechanism 16 at a desired position relative to the conveyor belt 14. A scraper 21 (
In other embodiments, the dividing mechanism(s) 16 can be integrally formed with, or fixably attached to, the conveyor belt 14. In yet other embodiments, the dividing mechanism(s) 16 can be provided on the top surface of the conveyor belt 14, i.e., the dividing mechanism is stretched above the top surface of the conveyor belt 14. The dividing mechanism(s) 16 extends vertically from the conveyor belt 14 a distance sufficient to prevent the articles 12 being heated from touching one another.
The mold 24 can be formed from a material that has suitable release properties, such as Teflon™ material, so that the food articles 12 do not stick or adhere to it. The material should also be chemically stable, for example, FDA approved, substantially microwave transparent, substantially electrically non-conductive, and high temperature resistant, for example, able to withstand temperatures of at least 300 degrees Fahrenheit without significant degradation. The mold 24 can be a separate element than the conveyor belt 14 so as to be removable therefrom. The mold 24 can be formed from an elastomer such that it can wrap around the conveyor belt 14 and be driven thereby. In a particular embodiment, the mold 24 can be formed from silicone rubber. In other embodiments, the mold 24 can be driven separate from the conveyor belt 14. A guiding device, such as illustrated in
In a particular embodiment, cheese is placed in the cavities 26 of the mold 24 and processed in the oven. As the water boils out of the cheese, it bubbles and puffs up and expands to form a product that is “foamy” in texture. The outer contour of the resulting product is maintained by the interior shape of the cavity 26. Without the mold 24, the cheese would melt and become thin and wide like a pancake.
In further embodiments, two or more molds 24 can be provided on the conveyor belt 14 to provide two or more lanes of food product to be simultaneously processed. In other embodiments, the cavities 26 can be integrally formed in the conveyor belt 14, thereby obviating the necessity of having a separate mold having cavities therein.
While this invention has been particularly shown and described with references to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the scope of the invention encompassed by the appended claims.
This application claims the benefit of U.S. Provisional Application No. 60/603,774, filed Aug. 23, 2004. The entire teachings of the above application(s) are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 60603774 | Aug 2004 | US |
