Abstract:
A system for reducing discharges from an oven prior to opening an oven door. In particular, the system includes a housing forming a cooking compartment arranged within the oven. The system also includes a purge passage extending through the housing into the cooking compartment and a cover arranged over a portion of the purge passage to removeably block the purge passage. An expelling port is included that extends from the cooking compartment through the housing. A controller is configured to remove the cover from blocking the purge passage to inject air into the cooking compartment through the purge passage and displace substances within the cooking compartment through the expelling port.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
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   STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
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   BACKGROUND OF THE INVENTION 
   The present invention relates generally to a system and method for reducing discharges from an oven and, more particularly, to a system and method for venting combination convection and steam ovens prior to the expiration of a cooking time. 
   Combination ovens provide the ability to cook foods using steam, hot-air convection, or both steam and convection. A motor driven fan is used to circulate air within a cooking chamber past electrical heating elements or gas heat exchange tubes to perform the convection functionality. To produce steam within the cooking chamber, a water line feeds water into the cooking chamber near the heating elements to vaporize the water. 
   This combination of convection heating with steam provides a system where food can be properly cooked significantly faster than with traditional ovens or even convection ovens alone. As a result, combination ovens have become a vital asset in commercial cooking environments that need to cook food quickly and, often, in large quantities. 
   Within any kitchen employing even traditional ovens, the heat produced by the oven can significantly affect the temperature of the kitchen, especially when the oven door is opened. In the case of combination ovens, the steam released upon opening the oven door may further raise the temperature in the kitchen. Furthermore, even if the kitchen is of sufficient size to allow the heat and steam to dissipate, the individual operating the combination oven is subjected to a concentrated release of heat and steam upon each opening of the oven door. In either case, this can present a less than desirable working condition, especially in commercial kitchens where one or more combination ovens are routinely used over long durations requiring repetitive openings and closings of the oven door. 
   Accordingly, it would be desirable to have a system and method to manage the discharge of steam and/or other substances from an oven upon opening of the oven door. 
   SUMMARY OF THE INVENTION 
   The present invention overcomes the aforementioned drawbacks by providing a system and method for reducing a steam level within an oven prior to the expiration of a cooking period. In particular, a controller is configured to open a passage formed in the oven to inject cool air into the oven prior to the expiration of a cooking period. A exhaust port is included through which heated air and steam can escape as they are displaced by the cool air entering through the oven. 
   In accordance with one aspect of the invention, a system for reducing a steam discharge from an oven is disclosed that includes a housing forming a cooking compartment arranged within the oven. The system also includes a purge passage extending through the housing into the cooking compartment, a cover arranged over a portion of the purge passage to removeably block the purge passage, and an expelling port extending from the cooking compartment through the housing. A controller is configured to remove the cover from blocking the purge passage to inject air into the cooking compartment through the purge passage and displace steam within the cooking compartment through the expelling port. 
   In accordance with another aspect of the invention, a system for reducing a steam discharge from an oven is disclosed that includes a cooking compartment arranged within the oven. The system also includes a purge passage extending through the oven into the cooking compartment and a cover arranged to removeably block the purge passage. A controller is configured to receive a cooking time and automatically move the cover to expose the purge passage prior to expiration of the cooking time to substantially purge the cooking compartment of steam. 
   In accordance with yet another aspect of the invention, a method of operating an oven is disclosed that includes setting a user-selected cooking time and automatically opening a purge passage formed in the oven to induce air external from the oven to enter the oven and substantially purge the oven of steam prior to the expiration of the user-selected cooking time. 
   Various other features of the present invention will be made apparent from the following detailed description and the drawings. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a front view of combination oven including a purging system according to the present invention; 
       FIG. 2  is a flow chart setting forth the steps of a purging process performed using the combination oven and purging system of  FIG. 1 ; and 
       FIG. 3  is a graph illustrating an operational timeline for the combination oven and purging system of  FIG. 1  when operated according to the purging process of  FIG. 2 . 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Referring now to  FIG. 1 , a combination oven  10  may include a generally rectangular housing  12  providing an oven door  114  through which food may be placed into a cooking compartment  16 . As is common in combination ovens, a water line  18  is included that injects water toward a fan  20  so that the water impinges upon the fan  20 . By contacting the fan  20 , the water is separated into small droplets providing a larger overall surface area which can be vaporized more efficiently by a heater  22 . In this regard, the heater  22  serves the dual purpose of heating the cooking compartment  16  of the combination oven  10  as well as evaporating the water injected into cooking compartment  16  to generate the steam necessary to function as a steamer. Similarly, the fan  20  serves the dual purpose of atomizing the water injected into the cooking compartment  16  as well as circulating the heat produced by the heater  22  to function as a convection oven. 
   The combination oven  10  also includes a purging system  24 . The purging system  24  includes a controller  26  having a timer  28  and an indicator  30 . The indicator  30  may be an audible indicator or a visual indicator, or even a combination thereof. Optionally, a purge button (not shown) could be included that allows manually initiation of the purging process described below. Furthermore, the indicator  30 , as will be described, may be configured to indicate an expiration of a cooking time, initiation of a purge period, or both. 
   The controller  26  is connected through a plurality of control lines  32  to the heater  22 , the fan  20 , a purge passage  34 , and the water supply line  18 . In particular, the controller  26  communicates with a valve  36  disposed along the water supply line  18  and a cover  38  disposed over purge passage  34 . 
   The combination oven  10  also includes a condensing system  40 . The condensing system  40  includes a condensing outlet  42  that extends from the cooking compartment  16  of the combination oven  10  into a condensing reservoir  44  having a condensing liquid  46 , preferably water, dispose therein. Therefore, during operation of the combination oven  10 , the condensing outlet  42  serves as a passage for excess steam as well as condensation formed within the cooking compartment  16  to be released into the condensing reservoir  44 . In this regard, the condensing liquid  46  cools and collects steam and/or grease as well as any odors associated therewith. 
   Referring now to  FIGS. 1 and 2 , operation of the combination oven  10  starts at process block  50  upon entry of a cooling time. In particular, the purging system  24  is configured to accept the cooking time via the timer  28  indicating the duration for which a user wishes food placed within the cooking compartment to be heated and steamed. Following at process block  52 , the controller  26  automatically selects a purging time within the duration of the cooking time. For example, the purging time may be set at a fixed interval prior to the expiration of the selected cooking time, or may be automatically calculated by the controller  26  based on the temperature and/or duration of the selected cooking time such that it is dynamically positioned at an optimal time prior to the expiration of the selected cooking time. 
   Continuing at process block  54 , once the purge time has been set, cooking is initiated by energizing the heater  22  and the fan  20  and by injecting water via the water supply line  18 . Accordingly, initialization of a cooking procedure is controlled by the controller  26  utilizing control lines  32 . It should be noted that at the outset of the desired cooking process the cover  38  over the purge passage  34  is in a closed position completely covering purge passage  34 . 
   As the cooking process progresses to decision block  56 , the controller  26  continually determines whether the purge time selected at process block  52  has been reached. If the purged time has not yet been reached  58 , the controller  26  determines whether the cooking time has expired at decision block  60 . However, if the purge time has not yet expired, preferably, the cooking time has not yet expired  62 . Therefore, the controller  26  continues to cycle through decision blocks  56  and  60  by checking whether the purge time or the cooking time has expired until the purge time is reached  64 . 
   Once the purge time has been reached  64 , the controller  26  automatically opens the cover  38  over the purge passage  34  at process block  66 . Alternatively, a purge button could be included to allow an operator to open the cover  38  once the purge time has been reached  64 . Additionally, such a purge button could be combined with the automatic opening ability for the controller  26  to allow an operator to open the cover  38  whenever desired. In either case, cool air from the exterior from the combination oven  10  is injected into the cooking chamber  16 . Simultaneously with opening the cover  32  or, alternatively, just prior thereto, the controller  26  closes the valve  36  to discontinue the supply of water delivered by the water supply line  18  into the cooking chamber  16 . That is, the controller  26  is configured to close the valve  36  to discontinue the supply of water injected into the cooking chamber substantially contemporaneously with opening the cover  32  to expose the purge passage  34 . In this regard, the generation of steam within the cooking chamber  16  is discontinued prior to or along with opening the cover over purge passage  34 . Additionally, it is contemplated that the heater  22  may be disengaged along with the closing of valve  36  so that the cool air entering the cooking chamber  16  through the purge passage  34  can substantially cool the cooking chamber  16 . However, in many applications, it may be preferable to allow the heater  22  to continue to operate so that the cooking chamber remains at a substantially consistent temperature in order to avoid cooling the food being cooked within the cooking chamber  16 , even though cool air is entering the cooking chamber through the purge passage  34 . 
   In either case, upon opening the purge passage  34  cool air enters the cooking chamber  16  and is aided by the fan  20  to advance across the cooking chamber. In this regard, the steam previously filling the cooking chamber  16  is pushed towards the condensing outlet  42  and into the condensing reservoir  44 . Therefore, upon the expiration of the cooking time  68 , the cooking chamber  16  is substantially free of steam. As such, when the indicator  30  signals the expiration of the cooking time, a user may open the oven door  14  without expelling substantial amounts of steam. 
   Referring now to  FIG. 3 , when a user enters a cooking time  70  of a duration extending from a start time  72  to an end time  74 , as described above, the controller calculates a purge period  76 . However, rather than extending beyond the end time  74  of the cooking time  70 , a purge time  78  is selected such that the cooking time  70  and the purge period  76  expire at the end time  74 . Therefore, according to the system and method described above, the controller is configured to receive a cooking time and automatically move the cover to expose the purge passage at the purge time  78  prior to the expiration of the cooking time  70  that was selected to substantially purge the cooking compartment of steam by the end time  74 . 
   Therefore, a system and method is provided for reducing a steam level within an oven prior to an expiration of a desired cooking time. Specifically, a controller is configured to open a passage formed in the oven to inject cool air into the oven prior to expiration of the cooking period. An exhaust port is provided through which steam can escape as it is displaced by the cool entering the oven. 
   It should be recognized that while the present invention has been described with respect to the discharge of steam from a combination oven, it is also applicable to other cooking systems to purge steam or other substances from an oven. For example, the above-described system and method could be utilized to purge certain odors and the like prior to opening an oven door. 
   It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein, but include modified forms of those embodiments including portions of the embodiments and combinations of elements of different embodiments as come within the scope of the following claims.