Apparatus, method and system for independently controlling airflow in a conveyor oven

Information

  • Patent Grant
  • 6592364
  • Patent Number
    6,592,364
  • Date Filed
    Friday, November 30, 2001
    22 years ago
  • Date Issued
    Tuesday, July 15, 2003
    20 years ago
Abstract
The present invention is an apparatus for distributing air to different regions of a conveyor oven. The apparatus has comprising one or more blowers to distribute the air. A lower plenum is connected to a blower. The lower plenum directs air to the lower side of a conveyor within the oven. An upper plenum is connected to a blower. The upper plenum directs air to the upper side of the conveyor.
Description




FIELD OF THE INVENTION




The present invention relates to conveyor ovens and, more particularly to, an improved conveyor oven having distinct heated air plenums that may be independently controlled to modify the cooking characteristics of the conveyor oven.




BACKGROUND OF THE INVENTION




Many restaurants use conveyor ovens to prepare food. Conveyor ovens typically cook or heat food by forced convection. A food service professional may place food such as a pizza or a dish of lasagna, for example, on the conveyor and the food is cooked or heated as it is conveyed through heated air within the oven.




Because customers like to have their meals prepared quickly, time is an important factor to consider when cooking food in conveyor ovens. The conveyor speed may be increased to quickly move food through the oven. The heat imparted to the food however, must also be increased or the food will remain cold and not satisfactory to customers. Simply increasing the temperature of the forced air in the oven is not necessarily an effective solution because the food is more likely to burn in high temperature air. Food service professionals may encounter problems when attempting to balance conveyor speed and oven air temperature to quickly and effectively cook or heat food.




Food service professionals encounter additional problems when preparing foods that require specialized cooking. Some pizzas, for example, are generally preferred if they have a crispy crust and a melted cheese topping. Cooking pizzas in this manner requires higher heat on the bottom of the pizza to properly cook the crust and controlled heat on the top of the pizza to melt, but not bun, the cheese topping. Because the conveyor oven has one open cooking chamber, independently controlling temperatures above and below a food may be difficult or impossible in conventional conveyor ovens.




Some conveyor ovens have manual balancing vents that allow food service professionals to adjust the amount of outside air that enters the Cooking chamber of a conveyor oven. Introducing outside air to the cooking chamber reduces the air temperature within the chamber. Restricting outside air to the cooking chamber increases the air temperature within the chamber. Adversely, however, adjusting the conveyor oven to properly cook a particular food is a process of trial and error. Several iterations, which could result in wasted food, may be required to properly adjust the conveyor oven.




Manual balancing vents also have many other problems. If conditions such as the ambient room temperature or the quantity of the food change, the food service professional must make additional adjustments to the vents, which consumes time and, if improperly adjusted, could result in wasted food. Because adjusting the ovens is more an art than a science, training new food service personnel is a costly process. Additionally, the vents are often rudimentary sheet metal plates that selectively cover holes in the oven. The plates do not accurately meter outside air and also become very hot, which may be hazardous to the food service professional. Necessary repeated adjustment of the vents increases the chance of a serious burn.




It would, therefore, be desirable to have an improved conveyor oven that does not improperly cook foods. It would also be desirable to have an improved conveyor oven that does not require difficult or uncertain adjustments to properly cook food. Further, it would be desirable to have an improved conveyor oven that does not require highly trained personnel to properly cook food.




SUMMARY OF THE INVENTION




The present invention is an apparatus for distributing air to different regions of a conveyor oven. The apparatus has comprising one or more blowers to distribute the air. A lower plenum is connected to a blower. The lower plenum directs air to the lower side of a conveyor within the oven. An upper plenum is connected to a blower. The upper plenum directs air to the upper side of the conveyor.




In one embodiment of the invention, a method of distributing air to different regions of a conveyor oven has the step of providing one or more blowers. A lower plenum is provided and attached to the one or more blowers. The lower plenum distributes air at the lower portion of a conveyor in a conveyor oven. An upper plenum is provided and attached to the one or more blowers. The upper plenum distributes air at the upper portion of the conveyor. Independently controlling the one or more blowers controls the volume of air that is distributed by the lower plenum and the upper plenum.




In another embodiment of the invention, a system to independently and variably control the temperature profile of a conveyor oven has a conveyor oven that has a cooking chamber. The system also has one or more independently controllable blowers. Plenums attached to the blowers distribute air to the cooking chamber. Independently controllable heating elements heat the air distributed by the plenums.











BRIEF DESCRIPTION OF THE DRAWINGS




For a more complete understanding of the present invention, including its features and advantages, reference is now made to the detailed description of the invention, taken in conjunction with the accompanying drawings of which:





FIG. 1

is a perspective exploded view of a conveyor oven that depicts an embodiment of the present invention;




FIGS


1


A-


1


C are principal axis views of the conveyor oven of

FIG. 1

;





FIG. 2

is perspective view of a plenum assembly that depicts an embodiment of the present invention;





FIGS. 2A-2C

are principal axis views of the plenum assembly of

FIG. 2

;





FIG. 3

is a cut-away view of a plenum housing that depicts an embodiment of the present invention; and





FIGS. 3A-3C

are principal views of the plenum assembly of FIG.


3


.











DETAILED DESCRIPTION OF THE INVENTION




While the making and using of various embodiments of the present invention is discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts that can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention.




A conveyor oven according to one embodiment of the present invention has many useful advantages over a typical conveyor oven. Typical conveyor ovens have an entrance and an exit. Food is placed on the conveyor at the entrance; it is carried through heated air in the cooking chamber; and, presumably, the food exits in a cooked state. As discussed above, a plenum may distribute heated air to the cooking chamber. Conventional ovens however, cannot effectively control the characteristics of air distributed within the oven. For example, a typical conveyor oven cannot control the manner in which different portions of the food are cooked. Consequently, conventional ovens may burn the top portion of the food while the bottom portion of the food exits the oven undercooked. A conveyor oven having the improvements described in detail below overcomes this and other disadvantages of conventional ovens.




As depicted in FIG.


1


and

FIGS. 1A-1C

, an oven


10


has a housing


12


. The housing


12


may house various components of the oven


10


such as plenum housings, heating elements, blowers, a power supply, switches, motors and the like. The housing


12


may be fabricated from stainless steel or other suitable material such as aluminum or carbon fiber. The housing


12


may be formed by a brake or fabricated from multiple pieces and bolted, screwed or welded together. The housing


12


may rest directly on a countertop or table or may have adjustable feet (not shown) to compensate for uneven surfaces.




A base


14


is attached to the lower portion of the housing


12


. The base


14


may be welded, bolted or screwed to the housing


12


. Similar to the housing


12


, the base


14


may also be fabricated from stainless steel, aluminum or other suitable material for the food service industry. The base


14


may impart additional stability to the oven


10


by distributing the weight of the oven


10


over a larger area. The dimensions of the base


14


will generally define the size of the oven


10


. Smaller capacity ovens


10


will usually have a smaller base


14


, whereas larger capacity ovens


10


will usually have a larger base


14


.




The base


14


provides support for a conveyor


16


. The conveyor


16


may be a wire mesh that conveys food through the oven


10


. A motor within the housing


12


typically drives the conveyor


16


but the conveyor


16


may also be driven by an external drive or other drive that is housed within the conveyor


16


. Alternative methods of driving the conveyor


16


will be apparent to those having ordinary skill in the art of conveyor ovens.




The base


14


may also support one or more lower plenums


18


. The lower plenums


18


deliver heated air or gasses to the lower side of a food that is cooked in the oven


10


. The lower plenums


18


may be fabricated from stainless steel, aluminum, molded plastic or other material that is suitable to channel heated air or gasses. The lower plenums


18


may simply rest on the base


14


or interlock into the base


14


, the housing


12


, or a plenum housing (described below). The lower plenums


18


may be easily removable from the oven


10


to facilitate cleaning and maintaining the oven


10


. The lower plenums


18


will be described in greater detail below.




A top


20


is attached to an upper portion of the housing


12


. The top


20


may be fabricated from materials such as stainless steel, aluminum or other materials known in the art of oven manufacturing. The size of the top


20


may have dimensions similar to the dimensions of the base


14


. The volume of space between the base


14


and the top


20


generally defines a chamber


22


of the oven


10


. The size of the chamber


22


determines the size of the conveyor


16


and ultimately determines the size or amount of food that may be cooked in the oven


10


during a particular time. Different sizes of ovens


10


may be manufactured by varying the lengths and widths of the top


20


and base


14


and varying the distance between the top


20


and the base


14


.




One or more baffles


30


may be removably attached to the top


20


or other portion of the oven


10


to contain and redirect heated air or gasses within the chamber


22


. The baffles


30


may help prevent heated air or gasses from escaping through the entrance or exit of the oven


10


, and thereby improve the efficiency of the oven


10


and the environment of a user. The baffles


30


may be removed from the front of the oven


10


to facilitate cleaning the chamber


22


. One or more side covers


32


may also be removably attached to the top


20


or other portion of the oven


10


. The side covers


32


may be insulated to help protect users from injuries caused by hot surfaces on the oven


10


.




The top


20


may support one or more upper plenums


24


. The upper plenums


24


deliver heated air or gasses to the upper side of food that is cooked in the oven


10


. The upper plenums


24


may also deliver heated air or gasses to the chamber


22


to thoroughly cook the entire food rather than cook only a particular region of the food, such as the top of a pizza, for example. The upper plenums


24


may be fabricated from stainless steel, aluminum, molded plastic or other material that is suitable to channel heated air or gasses. The upper plenums


24


may interlock into the top


20


, the housing


12


, or the plenum housing (described below). The upper plenums


24


may be easily removable from the oven


10


to facilitate cleaning and maintaining the oven


10


.




Referring now to FIG.


2


and

FIGS. 2A-2C

, a plenum assembly includes an upper plenum housing


40


and a lower plenum housing


42


. An upper motor


44


within the upper plenum housing


40


drives an upper blower


46


. Similarly, a lower blower motor


48


drives a lower blower


50


. Separate motors


44


,


48


may be independently controlled to differentiate airflow between the upper plenum


24


and the lower plenum


18


. Independently controlled airflow allows a user to more precisely control the cooking process. For example, more air, at a higher temperature, may be directed to the through the lower plenum


18


to most effectively cook and crisp the crust of a pizza. During the same cooking process, less air, at a lower temperature, may be directed through the upper plenum


24


to properly heat pizza toppings and melt cheese on the pizza. If the same temperature air were directed to both upper and lower surfaces of the pizza, the crust could be undercooked or the cheese could be burned.




The blowers


46


,


50


within the housing


12


may force the heated air or gasses into the plenums


18


,


24


. The plenums


18


,


24


may be tapered towards their distal ends to maintain air or gas velocity along the length of the plenums


18


,


24


. The heated air or gasses may be discharged from the plenums


18


,


24


through a series of distribution ports


52


in the lower surface of the upper plenum


24


and the upper surface of the lower plenum


18


. The series of distribution ports


52


may be sized and arranged to deliver an appropriate volume of heated air or gasses and properly cook food within the oven


10


. Heated air or gasses from the upper plenum


24


may be directed to impinge on the upper surface of the food while heated air or gasses from the lower plenum


18


may be directed to impinge on the lower surface of the food. This directional distribution of heated air or gasses aids in cooking separate portions of foods such as the meat or cheese toppings on a pizza, for example.




Turning now to FIG.


3


and

FIGS. 3A-3C

, a cutaway view of the upper plenum housing


40


is depicted in detail. Although the upper plenum housing


40


is depicted, the lower plenum housing


42


functions in a similarly and both upper and lower components will be discussed with reference to FIG.


3


. The blowers


46


,


50


may draw air from the oven chamber


22


as shown generally by arrow


58


. Upon starting the oven


10


, ambient air will be drawn through the entrance and exit of the oven


10


into the blowers


46


,


50


. The air may then be distributed into the plenum housings


40


,


42


. The plenum housings


40


,


42


have a heating element


54


within the air path to heat air that is moved by the blowers


46


,


50


. The heating element


54


may heat the air by electrical resistance, combustion, or infrared heating, for example. Other components to heat the air within the oven


10


will be apparent to those having ordinary skill in oven design.




Each branch of the plenum housings


40


,


42


may have a separate heating element


54


. Each heating element


54


may be independently controlled to deliver different a temperature air to different regions of the chamber


22


. For example, in an oven


10


that has front and rear branches of the plenums


18


,


24


, air to each of the branches of the plenums


18


,


24


may be heated to a different temperature according to the cooking characteristics of a particular food. Consequently, different temperature air may be directed to different regions of the chamber


22


.




Additionally, the heating elements


54


and the speed of the blowers


46


,


50


may be simultaneously controlled by a computer processor (not shown) to more precisely control the temperature profile of the chamber


22


. A series of thermocouples (not shown) placed within the chamber


22


may monitor the oven temperature in real-time. The computer processor may compare the information from the thermocouples to a desired temperature profile and adjust the output of the blowers


46


,


50


and the heating elements


54


accordingly. Other methods of controlling the temperature profile within the chamber


22


will be apparent to those having ordinary skill in control theory.




After the air is forced over the heating element


54


, the air continues to flow through the plenum housings


40


,


42


and is delivered to the plenums


18


,


24


. Arrows


60


generally designate this airflow from the plenum housings


40


,


42


. The airflow may be collimated by a series of vanes


56


within the plenum housings


40


,


42


. The vanes


56


may be thin strips of metal, plastic, or other suitable material that are spot welded, screwed, glued or otherwise fastened in the flow path of the air. The vanes


56


are designed to redirect, distribute and equalize airflow across the cross section of the plenum housings


40


,


42


and the plenums


18


,


24


. Collimated air is more efficiently delivered through the plenums


18


,


24


and, consequently, into the chamber through the distribution ports


52


. As a result, the vanes


56


alter airflow characteristics to improve heat distribution within the chamber


22


.




Heated air circulates within the chamber


22


and cooks or heats the food on the conveyor


16


. Because the blowers


46


,


50


draw air from the chamber


22


, the blowers


46


,


50


draw heated air after the oven


10


has been operating for a period of time and the heating elements


54


impart additional heat to the air. If the heating elements


54


and the blowers


46


,


50


are operated at a steady rate, the temperature, within the chamber


22


will eventually reach a state of equilibrium. Varying environmental conditions such as room temperature changes and the addition of cold food products to the chamber


22


will alter the temperature profile of the chamber


22


. Independent and variably controllable heating elements


54


may add or reduce heating to compensate for changes in a proper temperature profile. Consequently, food may be properly cooked in a consistent manner.




Whereas the invention has been shown and described in connection with the preferred embodiment thereof, it will be understood that many modifications, substitutions and additions may be made which are within the intended broad scope of the appended claims. There has therefore been shown and described an improved conveyor oven that accomplishes at least all of the above stated advantages.



Claims
  • 1. An apparatus for distributing air to different regions of a conveyor oven comprising:one or more blowers; a lower plenum connected to the one or more blowers, for directing air to the lower side of a conveyor within the oven; an upper plenum, having an upper front plenum branch to direct air to the beginning of the conveyor and a upper rear plenum branch to direct air to the end of the conveyor, connected to the one or more blowers, for directing air to the upper side of the conveyor; an upper front heating element to heat air directed by the upper plenum front plenum branch; and an upper rear heating element to heat air directed by the upper plenum rear plenum branch.
  • 2. The apparatus of claim 1 wherein the lower plenum has a lower front plenum branch to direct air towards the beginning of the conveyor and a lower rear plenum branch to direct air towards the end of the conveyor.
  • 3. The apparatus of claim 3 further comprising a lower front heating element to heat air directed by the lower front plenum branch and a lower rear heating element to heat air directed by the lower rear plenum branch.
  • 4. The apparatus of claim 1 wherein the lower plenum further comprises one or more heating elements to heat the air.
  • 5. A method of distributing air to different regions of a conveyor oven comprising the steps of:providing one or more lower blowers; providing one or more upper blowers; providing a lower plenum attached to a lower blower, the lower plenum for distributing air at the lower portion of a conveyor in a conveyor oven; providing an upper plenum attached to an upper blower, the upper plenum for distributing air at the upper portion of the conveyor; and independently controlling the one or more blowers to control the volume of air that is distributed by the lower plenum and the upper plenum.
  • 6. The method of claim 5 further comprising the step of providing a heating element to heat the distributed air.
  • 7. The method of claim 5 wherein the upper plenum has a front plenum branch to distribute air to the beginning of the conveyor and a rear plenum branch to distribute air to the end of the conveyor.
  • 8. The method of claim 5 wherein the lower plenum has a front plenum branch to distribute air to the beginning of the conveyor and a rear plenum branch to distribute air to the end of the conveyor.
  • 9. The method of claim 5 wherein the upper plenum has an upper front plenum branch to distribute air to the beginning of the conveyor and an upper rear plenum branch to distribute air to the end of the conveyor and wherein the lower plenum has a lower front plenum branch to distribute air towards the beginning of the conveyor and a lower rear plenum branch to distribute air towards the end of the conveyor.
  • 10. The method of claim 9 further comprising the steps of providing:an upper front heating element to heat air distributed by the front plenum branch and an upper rear heating element to heat air distributed by the rear plenum branch; and a lower front heating element to heat air distributed by the front plenum branch and a lower rear heating element to heat air distributed by the rear plenum branch.
  • 11. The method of claim 10 further comprising the step of independently controlling the upper front heating element, the upper rear heating element, the lower front heating element and the lower rear heating element.
  • 12. A system to independently and variably control the temperature profile of a conveyor oven comprising:a conveyor oven having a cooking chamber; two or more independently controllable blowers, comprising one or more upper blowers and one or more lower blowers; an upper plenum, attached to an upper blower, to distribute air to the cooking chamber; a lower plenum, attached to a lower blower, to distribute air to the cooking chamber; and one or more independently controllable heating elements to heat the air distributed by the one or more plenums; wherein the temperature and volume of distributed air in the upper plenum are independently controllable from the temperature and volume of distributed air in the lower plenum.
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