BACKGROUND

Conveyor ovens are widely used for cooking pizzas and a wide variety of other food products. Examples of such ovens are shown, for example, in U.S. Pat. Nos. 5,277,105, 6,481,433 and 6,655,373, as well as U.S. Pat. Nos. 8,281,779, 8,087,407, and 9,585,401.

Conveyor ovens are typically large metallic housings with a heated tunnel extending through them and a conveyor running through the tunnel. In many cases, such conveyor ovens are either 70 or 55 inches long, although they may be constructed in any other suitable size. The conveyor transports food products through the heated oven tunnel at a speed which cooks food products during their transit through the tunnel. Conveyor ovens typically include a heat delivery system including one or more blowers which supply heat to the tunnel through passageways leading to metal fingers opening into the oven tunnel. Such metal fingers are often located above and below the conveyor. The metal fingers act as airflow channels that deliver streams of hot air which impinge upon the surfaces of the food products passing through the tunnel on the conveyor. In modern conveyor ovens, a microprocessor-driven control panel generally enables the user to regulate heat delivery (e.g., to control the temperature within the oven, the heat output of the heat delivery system, and the like), the speed of the conveyor, and other oven functions to properly cook food product being transported through the oven.

Conveyor ovens are generally controlled with the intent to achieve repeatable and controllable heating of the oven chamber. The conveyor generally travels at a speed calculated to properly cook food products on the conveyor belt during the time period required for the conveyor to carry the food products through the entire length of the oven tunnel. In some conveyor ovens, other food products requiring less time to cook may be placed on the conveyor at a point partially through the oven chamber so that they travel only a portion of the length of the tunnel. A pizza is an example of a food product which might require the full amount of cooking time in order to be completely cooked in the oven. A sandwich is an example of a product which might require only a portion of the full cooking time. In conventional conveyor ovens, the time required to cook a pizza, for example, from an uncooked state to a fully cooked state is in excess of 4 or 5 minutes, regardless of how much heat and air flow are supplied to the conveyor supporting the pizza.

Conveyor ovens are typically used in restaurant kitchens and commercial food manufacturing facilities. Typically, they are kept running for extended periods of time, including periods when food products are not being cooked. Since the inlet and outlet ends of the oven tunnel are open, this means that heat and noise are continuously escaping from the conveyor oven tunnel into the surrounding environment. This escape of heat wastes energy, and also warms the surrounding environment often to unnecessary and uncomfortable levels. This is particularly the case where the conveyor oven is being used in relatively cramped restaurant kitchen environments. The escaping noise is also undesirable, since it may interfere with interpersonal communication among those working near the oven.

Conventional conveyor ovens also provide users with limited ability to reduce energy losses while running at less than full capacity. In many cases, users only have the ability to turn such ovens on or off, which often involves unacceptably long shut-down and/or start-up times. Therefore, it is often necessary to leave such ovens on (or in a state in which they consume excessive energy) despite the waste of fuel or other energy supplied to the ovens when cooking food intermittently. It is not uncommon for a conventional conveyor oven to be left running in full production mode for substantially the entire period of time a restaurant or other cooking facility is open.

It is generally desirable to maintain controlled heating and temperatures within the tunnel of a conveyor oven during operation. Among the challenges to be overcome in achieving such controlled heating and temperatures are the inherent variations in heating from oven to oven due to variations in the internal physical environment of otherwise identical ovens. A more significant challenge is the constantly changing physical and thermal configuration of the tunnel as food products being cooked pass from one end of the tunnel to the other. For example, raw pizzas entering the inlet to the tunnel constantly change the physical and thermal configuration of the tunnel environment as they advance to the other end, while drawing and emitting ever-varying amounts of heat. As a result, temperatures within the oven can vary greatly from one end of the tunnel to the other.

Currently, the most common technique for controlled heating through the length of the conveyor oven tunnel involves monitoring temperatures near the inlet and outlet ends of the heated tunnel to maintain a predetermined average temperature over the length of the tunnel. Thus, for example, as a cold raw pizza enters the inlet to the tunnel, thereby causing a sudden drop in the tunnel temperature at the inlet, the drop in temperature is sensed, and more heat is supplied to the tunnel to raise the temperature at or near the inlet temperature sensor. Unfortunately, this can also raise the temperature at the outlet of the oven, which causes the temperature sensor at the outlet to trigger a heating reduction to prevent an excessive temperature at or near the tunnel outlet. In this way, temperature sensors near the inlet and outlet of the oven help to achieve controlled heating of the tunnel to generally maintain a target average temperature.

However, controlled and repeatable heating along the length of the heated tunnel (e.g., whether a desired uniform or non-uniform temperature profile along the length of the tunnel) cannot be achieved in this way. Thus, food products traveling through the oven do not experience controlled and repeatable heating which, it has been discovered, makes it necessary to slow the conveyor to a speed which completes the cooking in more time than would be the case if a desired temperature profile could be achieved throughout the length of the heated tunnel. In other words, improved heating control from one end of the tunnel to the other may reduce required cooking times and increase cooking quality.

Additionally, in many applications it is necessary to be able to operate the conveyor oven using either side as the inlet, by running the conveyor belt either from left-to-right for a left side inlet, or from right-to-left for a right side inlet. To be most successful in such interchangeable applications, it is particularly desirable to have greater control over the heating and temperature profile of a conveyor oven along the length of the conveyor oven tunnel.

SUMMARY

Some embodiments of the present invention provide a conveyor oven for cooking food, the conveyor oven comprising an oven chamber in which food is cooked; a conveyor moveable to convey the food within the oven chamber; a burner assembly operable to emit a flame to heat air for convection cooking of food moving within the oven chamber on the conveyor; a burner tube extending into a compartment and positioned to receive at least a portion of the flame emitted by the burner assembly; a first passive tube and a second passive tube in the compartment positioned opposite the burner tube, wherein the first and second passive tubes each include an end opposite and facing the burner tube and an outer wall; a baffle strip extending between the first and second baffle tubes; and a fan in fluid communication with the compartment and operable to deliver heated air from the compartment to the oven chamber for convection cooking of food moving through the oven chamber on the conveyor.

In some embodiments, a conveyor oven for cooking food is provided, and comprises an oven chamber in which food is cooked; a conveyor moveable to convey the food within the oven chamber; a burner assembly operable to emit a flame to heat air for convection cooking of food moving within the oven chamber on the conveyor; a burner tube extending into a compartment and positioned to receive at least a portion of the flame emitted by the burner assembly; a passive tube in the compartment positioned opposite the burner tube, wherein the passive tube includes an end opposite and facing the burner tube and an outer wall; a baffle plate positioned between the passive tube and the burner tube; and a fan assembly in fluid communication with the compartment and operable to deliver heated air from the compartment to the oven chamber for convection cooking of food moving through the oven chamber on the conveyor.

Some embodiments of the present invention provide a conveyor oven for cooking food, the conveyor oven comprising: a housing having an oven chamber in which food is cooked; a conveyor moveable to convey the food within the oven chamber; a burner assembly operable to emit a flame to heat air for convection cooking of food moving within the oven chamber on the conveyor; a burner tube extending into a compartment and positioned to receive at least a portion of the flame emitted by the burner assembly; a passive tube in the compartment positioned opposite the burner tube; a first shelf positioned in the housing, in fluid communication with the compartment, and movable with respect to the compartment; a second shelf positioned in the housing, in fluid communication with the compartment, and movable with respect to the compartment; a first fan or a first motor attached to the first shelf and movable with the first shelf with respect to the compartment; and a second fan or a second motor attached to the second shelf and movable with the second shelf with respect to the compartment; wherein the first and second shelves are both located in the housing higher than the burner tube and the passive tube, or are both located in the housing lower than the burner tube and the passive tube; and wherein the first shelf is independently moveable with respect to the second shelf.

