Abstract:
A grease removal system for a combination oven, requiring venting and condensation of steam, conducts excess grease through the same drainpipe as the steam to a water-filled condenser, then segregates the grease within a reservoir wall. In this way, a single opening may serve to remove both excess steam pressure and grease and temperature-moderated grease may be readily pumped to a convenient location.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    Commercial ovens may provide for closed system operation in which the oven volume is substantially sealed to retain heat and moisture and provide energy savings. Such closed system operation is particularly desirable for “combination ovens” that provide the ability to cook food using steam and fan driven (forced convection) hot air but may also be used in convection ovens (without steam) and rotisserie ovens. 
         [0002]    In closed-system ovens, excess pressure within the cooking cavity caused by expanding steam and air may be vented through a condenser where the steam is cooled before exiting to the outside air, reducing heating of the kitchen environment. In common condenser designs, the steam is passed through a water bath which cools and condenses the steam. The temperature of the water bath is monitored and fresh, cool water is introduced into the water bath as the temperature rises. Excess water from the bath passes through an overflow into the building drain system. 
         [0003]    Some foods, when cooked, produce significant quantities of grease which may be allowed to drain away from the food to be captured in a drip pan positioned at the bottom of the oven. The drip pan may be attached to a drain line to allow gravity draining of the grease into a removable collection container. One method of providing such a drainage system is described in U.S. Pat. No. 7,421,942 entitled: “Grease Collection System for Oven”, assigned to the assignee of the present invention, and hereby incorporated by reference. 
         [0004]    Gravity drainage systems for grease can be an obstacle to efficient stacking of ovens if the lowermost oven is not sufficiently elevated to permit positioning of the drain containers beneath the oven. The drainage path for excess grease is normally separate from the exit path of steam through the condenser so that the overflow water from the condenser does not discharge grease into the drains where it may congeal. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides a grease drain system that significantly simplifies construction of a closed system oven by discharging steam and grease through the same outlet into a reservoir in the condenser assembly. Grease is removed from the condenser reservoir by a pump system efficiently operated on a pulse basis taking advantage of the accumulating capacity of the reservoir. The pump eliminates or reduces the height differentials required in pure gravity drainage systems allowing the oven to be mounted closely to the floor. The cooling water used to manage steam exhaust may also moderate temperature of the grease for better pumping and handling. 
         [0006]    Specifically, the invention provides an oven with a cooking volume sealable with a door, the cooking volume communicating with a heater to heat the same. A condenser chamber communicates with the cooking volume through a drain opening, the condenser chamber adapted to hold a pool of water at a water level and having an exit port communicating with atmosphere outside of the cooking volume. A grease segregation wall intersects the water level to segregate grease passing through the drain opening to a reservoir area within the condenser chamber. There it can be removed by a pump connected through an opening in the condenser chamber communicating with the reservoir area so that the pump may pump grease from the reservoir area out of the condenser chamber. 
         [0007]    It is thus one feature of at least one embodiment of the invention to provide an integrated steam condenser and grease handling system simplifying construction of the oven and the removal of grease from the oven. 
         [0008]    The grease segregation wall may pass from a bottom of the condenser chamber to a point above the water level. 
         [0009]    It is thus one feature of at least one embodiment of the invention to permit the free flow of steam past the separator wall to permit condenser function. 
         [0010]    In one embodiment, the grease segregation wall may provide an upwardly open container within the condenser chamber enclosed on all sides. 
         [0011]    It is thus one feature of at least one embodiment of the invention to better segregate the grease from the cooling water to reduce water entrained within the grease such as may increase disposal costs. 
         [0012]    The oven may further include a baffle extending from a top of the condenser chamber to below the water level so that gases passing from the cooking volume through the condenser chamber to the exit port must pass through the pool of water. 
         [0013]    It is thus one feature of at least one embodiment of the invention to provide a simple method of insuring condensation of the steam by forcing it to pass underneath the baffle wall into the cooling water. 
         [0014]    In an alternative embodiment, the grease segregation wall may be spaced from a bottom of the condenser chamber to allow communication of water between the reservoir area and other areas of the condenser chamber below the grease segregation wall but to block communication of grease floating on the water between the reservoir area and the other areas of the condenser chamber. 
         [0015]    It is thus one feature of at least one embodiment of the invention to integrate the functions of the baffle wall and grease segregation wall into a single structure for reduced cost. It is another feature of this embodiment to provide rapid cooling of expelled grease by direct contact cooling water. 
         [0016]    The oven may further include a temperature sensor communicating with the cooking volume to measure the temperature therein and a user input console for generating electrical signals based on inputs by a user of the oven. An electric controller may communicate with the heater element, the pump, and the temperature sensor and execute a program stored in a non-transient medium to: (a) receive commands from the user indicating a cooking schedule associated with cooking times and temperatures; (b) monitor the temperature sensor and control the heater element to implement the indicated cooking schedule of cooking times and temperatures; and (c) activate the pump according to a selection of a cooking schedule indicating cooking of a grease producing foodstuff. 
         [0017]    It is thus one feature of at least one embodiment of the invention to permit dual-mode operation of the oven both for foods that release grease while providing improved pump energy efficiency. 
         [0018]    The command from the user may identify a foodstuff, such as chicken. 
         [0019]    It is thus one feature of at least one embodiment of the invention to provide automatic grease removal in a manner invisible to the user that is automatically invoked based on an imputed purpose of the oven. 
         [0020]    The pump may be activated intermittently during the cooking process for a time required to drain the reservoir. 
         [0021]    It is thus a feature of at least one embodiment of the invention to provide for preferred energy efficiency in the operation of the pump by accumulating grease for a period of time. 
         [0022]    The activation of the pump may be dependent upon cooking volume temperature. 
         [0023]    It is thus a feature of at least one embodiment of the invention to provide pump operation that is sensitive to imputed rate of grease production. 
         [0024]    The oven may include an electronic switch having an operator operable by a user for activating the pump when the electronic switch is actuated by the user. 
         [0025]    It is thus one feature of at least one embodiment of the invention to provide manual operation of the pump for cleaning and the like. 
         [0026]    The oven may further include a temperature sensor sensing the temperature of water in the condenser chamber and a freshwater inlet valve metering freshwater into the condenser chamber when a temperature of water in the condenser chamber exceeds a predetermined threshold. 
         [0027]    It is thus one feature of at least one embodiment of the invention to automatically accommodate additional heat load produced by grease. 
         [0028]    The oven may include an overflow lip defining a height of the water level above which water flows over the overflow lip. 
         [0029]    It is thus one feature of at least one embodiment of the invention to provide a simple method of water temperature control and level control without problems of grease entering into an overflow drain. 
         [0030]    The drain opening may be a substantially vertically extending tube and the reservoir area is directly beneath the drain opening or the drain opening may include a horizontally extending portion, for example extending within the condensation chamber. It is thus one feature of at least one embodiment of the invention to permit direct discharge of grease from the oven to eliminate potentially dangerous pooling of grease within the oven, while permitting pump management of the discharge grease. 
         [0031]    These particular features and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0032]      FIG. 1  is a simplified perspective view of a combination oven suitable for use with the present invention showing the elements of the convection fan, heater element (e.g., a gas heat exchanger or electric heating element), controller board, and control panel; 
           [0033]      FIG. 2  is a fragmentary cross-section along line  2 - 2  of  FIG. 1  showing a first embodiment of the grease management system of the present invention providing for the cooling of escaping steam and collection of grease through a common drain opening; 
           [0034]      FIG. 3  is an orthographic view of the grease management system showing connection to other oven elements including the controller board; 
           [0035]      FIG. 4  is a simplified flowchart of the program executed by the controller board of  FIG. 1  for managing grease; 
           [0036]      FIG. 5  is a figure similar to that of  FIG. 3  of an alternative embodiment of the present invention providing increased cooling of the grease; and 
           [0037]      FIG. 6  is a figure similar to that of  FIG. 2  of the alternative embodiment of  FIG. 5 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0038]    Referring now to  FIG. 1 , a closed-system commercial oven  10  suitable for providing steam and convection air cooking provides a housing  12  defining a cooking volume  14  open toward a front of the housing  12 . The cooking volume  14  is accessible through a door  16  connected by a hinge at one vertical side of the cooking volume  14  to sealingly close that cooking volume  14  during cooking operations. A latch assembly (not shown) may hold the door  16  in the sealed position or may be released to allow the door  16  to open. 
         [0039]    Positioned within the housing  12  and communicating with the cooking volume  14  is a forced convection fan  18  providing a stream of air into the cooking volume  14  and across a heater element  20  (shown schematically) providing heat for cooking items, in the cooking volume  14  and for vaporizing steam. The heater element may be an electric heating element or a heat exchanger receiving heat from a gas flame or the like. The steam may be produced by a valve-controlled water jet  19  typically impinging on the fan  18  and a portion of the heater element  20  proximate to the fan  18 . Ovens of this type are commercially available from the Alto-Shaam Inc. of Menomonee Falls, Wis. and are described generally in U.S. Pat. No. 6,188,045 “Combination Oven with Three Stage Water Atomizer” hereby incorporated by reference. 
         [0040]    A controller board  21  within the housing  12  may provide an electronic computer or microcontroller receiving instructions from a control panel  23  accessible on the front of the oven  10 , and having, for example, membrane switches that may be activated by user. As will be discussed in greater detail below, the controller board  21  generally provides an electronic computer executing a stored program to control the heater element  20 , fan  18 , and the waterjet  19 , turning them on and off as necessary to implement a particular cooking schedule. 
         [0041]    The cooking volume  14  may further provide for a removable drip pan  22  being a metal tray fitting adjacent to the bottom of the cooking volume  14  and having a drainage aperture  24  through which collected grease and oil from cooked product within the cooking volume  14  may pass. 
         [0042]    Referring now to  FIG. 2 , the drip pan  22  is positioned with respect to a bottom wall  26  of the cooking volume  14  so that the drainage aperture  24  is located directly above a drainpipe  28 , the latter being a short tube extending vertically downwardly from the bottom wall  26  to a condenser chamber  30  positioned beneath the bottom wall  26 . The drainpipe  28  allows grease and oil  33  passing through the drainage aperture  24  to enter the condenser chamber  30  under the influence of gravity. In an alternative embodiment (not shown) the drainpipe  28  may extend horizontally for a short distance before or after it is received within the condenser chamber  30 . 
         [0043]    Referring now also to  FIG. 3 , the condenser chamber  30  provides a generally enclosed box having a bottom wall  32  sloping downwardly from an end closest to the drainpipe  28  to an opposite end adjacent to an, exit port  34 . Upstanding sidewalls  36  around the periphery of the bottom wall  32  retain, a pool of water having a water level  46  and accumulated grease within the condenser chamber  30  as will be described. These upstanding sidewalls  36  are joined at their upper edges to a generally horizontal upper wall  38  adjacent to a bottom of the cooking volume  14  and having an opening for receiving the drainpipe  28  therethrough. The lower end of the drainpipe  28  passing into the condenser chamber  30  stops above the bottom wall  32  and above a water level  46 . 
         [0044]    The volume of the condenser chamber  30  is divided into a reservoir area  40  directly beneath the drainpipe  28  and a non-reservoir area  42  being the remaining area outside of the reservoir area within the condenser chamber  30 . The reservoir area  40  may be defined by upstanding reservoir walls  44  joining with the sidewalls  36  to define an upwardly open container closed on all sides and positioned beneath the drainpipe  28 . The reservoir walls extend upward from the bottom wall  26  to a position above a water level  46  but below the upper wall  38  so as to provide a path of steam  48  from the drainpipe  28  past the reservoir walls  44  to the exit port  34 . The exit port  34  generally connects to the sanitary sewer line but with some venting arrangement which allows the escape of gases. For example, the exit port  34  may discharge onto a floor drain or the like. As noted, it is desirable that excess grease not be introduced into the sanitary sewer such as may create clogging problems. 
         [0045]    Generally grease  33  will drop through the drainpipe  28  to be retained by the reservoir area  40  whereas steam  48  will not be so constrained but will pass into the non-reservoir area  42 . The non-reservoir area  42  will be filled with cool water  52  and controlled in height to the water level  46 . A baffle plate  54  may extend downward from the upper wall  38  through the water level  46  to beneath the level of the water  52  but above the bottom wall  32 . The baffle plate  54  thereby forces heated air and steam  48  passing from the drainpipe  28  to the exit port  34  to pass through the cool water  52  thus condensing the steam and cooling the associated air  56  exiting the exit port  34  as indicated by an arrow. 
         [0046]    The water  52  is maintained at a cool temperature by a freshwater inlet valve  57  adding makeup water  55  through an opening in the upper wall  38 . The freshwater inlet valve  57  is under the control of the controller board  21  which may also communicate with a temperature gauge  62  so that additional water is added through valve  57  only when the temperature of the existing water  52  rises above a certain amount. As water is admitted through valve  57  excess water  52  drains out through the exit port  34  as indicated by arrow, the lower edge of which provides an overflow lip  47  defining the water level  46 . 
         [0047]    The reservoir area  40  communicates through a grease discharge opening  64  passing through a sidewall  36  to discharge accumulated grease  33  and pass it to a suction pump  68 . For this purpose the grease discharge opening  64  in this embodiment may be positioned near the bottom wall  32 . The suction pump  68  may pump the grease through a conduit  70  of arbitrary length to a collection vessel  72 , for example, removed from the oven  10  for convenient access. The removal path may be substantially horizontal allowing grease to be readily collected from an oven  10  placed closely adjacent to a floor that would otherwise preclude the placement of a grease collection bucket at a point lower than the drainpipe  28 . The suction pump  68  may also communicate with the controller board  21  to be controlled thereby. 
         [0048]    Steam passing through the drainpipe  28  may also pass into a steam collection port  74  that may recirculate back to the oven cavity. The steam collection port  74  may hold a temperature sensor  76  communicating with the controller board  21  which may be used to provide steam temperature information useful for control of the oven  10 . 
         [0049]    Referring now to  FIGS. 3 and 4 , the controller board  21  may execute a stored program  58  held in a memory  61  using a processor  60  communicating with memory  61 . The program  58  may selectively operate the pump  68  both on a periodic basis during the cooking of foods that express grease and only in cooking modes associated with foods that express grease in order to conserve energy. The program  58  implements this functionality by communicating with a cooking program also executed by the controller board  21  and the control panel  23 . The cooking program generally includes and implements pre-stored schedules of cooking times and temperatures for different foods. The cooking program may also allow manual setting of temperatures and times. 
         [0050]    As indicated by process block  78 , a pump cycle in which pump  68  is turned on for a brief period of time may be initiated by indication of a particular cooking mode captured by the cooking program through cooking mode buttons  80  on control panel  23 , such as may indicate, for example, a desired cooking schedule for cooking of chicken. In this regard, a particular button  80  may be labeled with indicia indicating roasted chicken, for example. Alternatively, a pump cycle may be initiated by pressing of a special grease purge button  82  indicating a desire to manually operate the suction pump  68 . 
         [0051]    Upon either such indication, the program  58  determines whether the temperature of the oven is sufficiently high for the generation of grease (and its mobility) as indicated by decision block  84 . If not the program loops at this point. 
         [0052]    If the temperature is sufficient, the program  58  checks to see whether the pump  68  has been operated recently according to a stored time value indicating its last operation per decision block  86 . The amount of time elapsed since the last operation of the pump  68  is compared to empirically developed data indicating approximate rate of filling of the reservoir area  40  as informed by the cooking mode of process block  78 . If the suction pump  68  has been operated within this interval, the program  58  may loop at decision block  86  until this time has elapsed. 
         [0053]    If the time elapsed since the last running of the suction pump  68  exceeds the stored filling rate interval of the reservoir area  40 , the program  58  proceeds to process block  88  and the pump is run for a fixed period of time sufficient to fully empty the reservoir area  40 . In this way, the pump  68  does not need to operate continuously and power is conserved. For example, the pump  68  may be activated first when the temperature of the oven is within five degrees of a set temperature on intervals of 20 minutes for a pumping duration of 60 seconds. 
         [0054]    Referring to  FIGS. 4 and 2 , the time delay between pump cycles implemented by decision block  86  provides a temperature acclamation of the discharge grease to more moderate temperatures. This temperature moderation of the grease  33  reservoir area  40  may occur through conduction, for example, through reservoir walls  44  and bottom wall  32  and allows the grease  33  to cool sufficiently to be readily handled and yet not so cool much as to prevent easy pumping by the suction pump  68 . 
         [0055]    Referring now to  FIGS. 5 and 6 , in an alternative embodiment, the reservoir walls  44  separating the reservoir area  40  from the non-reservoir area  42  may also implement the function of the baffle plate  54 . This is done by positioning the reservoir walls  44  to extend downward from the upper wall  38  below the water level  46  but above the bottom wall  32 . This embodiment segregates the grease  33  by exploiting the fact that the grease  33  will have lower density than the water  52  and thus will float on its surface and can be blocked by a reservoir wall  44  that does not extend fully to the bottom wall  32  of the condensation chamber  30 . In this embodiment, the grease discharge opening  64  may be positioned approximately at the water level  46 . This embodiment provides more intimate contact between the grease  33  and the water to provide improved cooling and eliminates an element of the chamber  30 . 
         [0056]    Certain terminology is used herein for purposes of reference only, and thus is not intended to be limiting. For example, terms such as “upper”, “lower”, “above”, “below”, “clockwise”, and “counterclockwise” refer to directions in the drawings to which reference is made. Terms such as “front”, “back”, “rear”, “bottom” and “side”, describe the orientation of portions of the component within a consistent but arbitrary frame of reference which is made clear by reference to the text and the associated drawings describing the component under discussion. Such terminology may include the words specifically mentioned above, derivatives thereof, and words of similar import. Similarly, the terms “first”, “second” and other such numerical terms referring to structures do not imply a sequence or order unless clearly indicated by the context. 
         [0057]    When introducing elements or features of the present disclosure and the exemplary embodiments, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of such elements or features. The terms “comprising”, “including” and “having” are intended to be inclusive and mean that there may be additional elements or features other than those specifically noted. It is further to be understood that the method steps, processes, and operations described herein are not to be construed as necessarily requiring their performance in the particular order discussed or illustrated, unless specifically identified as an order of performance. It is also to be understood that additional or alternative steps may be employed. 
         [0058]    References to a controller, computer or processor or its equivalent can be understood to include one or more computational devices including microprocessors, field programmable gate arrays, and application specific integrated circuits that can implement state aware logic and that can communicate in a stand-alone and/or a distributed environment(s), and can thus be configured to communicate via wired or wireless communications with other processors, where such one or more processor can be configured to operate on one or more processor-controlled devices that can be similar or different devices. Furthermore, references to memory, unless otherwise specified, can include one or more processor-readable and accessible memory elements and/or components that can be internal to the processor-controlled device, external to the processor-controlled device, and can be accessed via a wired or wireless network.