Abstract:
A ventless fume hood is integrated with an oven to anticipate a conclusion of the cooking schedule executed by the oven and in this way to provide direct venting of the oven cavity before the oven door is opened. Proper venting of a multimode combination oven may be thereby performed and the door may be opened up immediately upon conclusion of the cooking schedule without the delay otherwise required to collect cooking fumes escaping through the partially open door.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the benefit of U.S. Provisional Application 61/874,108 filed Sep. 5, 2013 and hereby incorporated by reference. 
     
    
     BACKGROUND OF THE INVENTION 
       [0002]    The present invention relates to combination ovens used in preparing food, and in particular, to a ventless hood for such an oven, the combination of oven and ventless hood providing rapid access to the oven interior at the conclusion of a cooking schedule. 
         [0003]    High-end 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 may cook food using steam and fan driven (forced convection) hot air, but is also useful in convection ovens (without steam) and rotisserie ovens. 
         [0004]    In closed-system ovens, expanding steam and air are vented so that the cooking process is performed without significant pressurization. This venting may occur through a condenser where the steam is cooled before exiting to the outside air, reducing the heating and humidification of the kitchen environment. In one common condenser design, 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. 
         [0005]    Such closed-system ovens can be used with so-called “ventless fume hoods” which provide internal filters to capture grease and cooking odors when the oven door is opened after a cooking schedule is complete. A common design for such ventless hoods provides an air intake positioned at the front of the oven just above the oven door. When the user attempts to open the oven door, a latch holds the oven door in a partially open position for a short period of time (for example, 20 seconds) to allow the ventless hood to capture and filter the air escaping through the door opening. After this time, the latch is released and the door may be fully opened. 
         [0006]    Advanced “multi-mode” closed-system ovens may provide the ability to switch between standard closed operation described above and “open” operation in which the oven is vented during all or portions of the cooking cycle, for example, for humidity control, browning, or the like. This venting operation may be controlled through one or more electrically actuable “dampers” which may open or close to introduce outside air into the oven. A multi-mode oven suitable for this purpose is described in U.S. patent application Ser. No. 13/868,423 filed Apr. 23, 2013, assigned to the assignee of the present invention and hereby incorporated by reference. 
         [0007]    When the dampers are open during the cooking cycle, grease and odors from an exhaust damper must be captured even though the oven door is closed and the ventless hood is not operating. The large door intake area needed by the ventless hood prevents a simple routing of the exhaust damper into the ventless hood without the odor and grease simply bypassing the filters and exiting backwards through the door intake area. On the other hand, constant operation of the ventless hood fan at a volume rate sufficient to capture odor or grease simultaneously from the damper and the large door intake area risks drawing so much an through the damper that the accuracy of the cooking process is adversely affected. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention provides a ventless fume hood for operation with a multi-mode oven, where the fume hood anticipates the conclusion of the cooking schedule to provide fan assisted venting of the oven through an internal channel before the oven door is opened. By eliminating the front door vent, the damper may be directly connected to the fume hood for passive filtration of grease and odor without the risk of filter bypass. Anticipating the opening of the door also allows the ventless fume hood fan to remain off during most of the cooking schedule to avoid introducing variations in the cooking process. Operating the ventless fume hood fan for completion of the cooking schedule further allows the oven door to be opened immediately without delay once the cooking process is concluded unlike with typical ventless hood designs. 
         [0009]    In one embodiment, the invention provides an oven having a housing with a door that can be opened to reveal a cooking volume containing a heater. A filter system, having a filter medium and a fan for moving air through the filter medium, connects to an exhaust channel communicating with the cooking volume through a second opening in the housing. An electronic computer controls the heater in accordance with a predetermined cooking schedule and activates the fan of the filter system in a venting process beginning at a time based on the cooking schedule, before a conclusion of the cooking schedule, to provide venting of the cooking volume before an anticipated opening of the door. 
         [0010]    It is thus a feature of at least one embodiment of the invention to allow the door to be promptly opened after conclusion of the cooking schedule by close integration of the ventless hood and the oven. By allowing the ventless hood to be controlled by the oven cooking schedule, a filtering process can be started before the doors open. 
         [0011]    The venting process may begin at a time based on a predetermined duration of the cooking schedule or at a temperature based on a predetermined temperature rise of the cooking schedule. 
         [0012]    it is thus a feature of at least one embodiment of the invention to provide flexible anticipation of the conclusion of the cooking schedule for different cooking modes that cook food for a given period of time or until a particular temperature rise is obtained. 
         [0013]    The exhaust channel may include a first electrically controlled damper for opening and closing the exhaust channel and the electronic computer may open this damper during the venting process. 
         [0014]    It is thus a feature of at least one embodiment of the invention to preserve the ability of the oven to operate in a substantially sealed mode during much of the cooking schedule if desired. By positively controlling the opening of the exhaust channel, inadvertent venting cost, for example, by action of the convection fan inside the oven may be controlled. 
         [0015]    The computer may also control a first electrically controlled damper according to the predetermined cooking schedule, but may override this control at the predetermined time to open the first electrically controlled damper. 
         [0016]    It is another feature of at least one embodiment of the invention to permit filtration of venting that occurs during a mixed mode cooking cycle when a venting damper is opened. By eliminating the large door vent, the exhaust channel may be connected directly to the filter system for passive filtering at low rates that minimize disruption to the cooking process. 
         [0017]    The oven may further include and intake channel communicating from the cooking volume to ambient air outside of the cooking volume through a third opening in the housing to provide intake air into the cooking volume during the venting process. 
         [0018]    It is thus a feature of at least one embodiment of the invention to permit high levels of air turnover for fast venting such as may require a source of makeup air. 
         [0019]    The intake channel may include a second electrically controlled damper and an electronic computer may open the second electrically controlled damper during the venting process. 
         [0020]    It is thus a feature of at least one embodiment of the invention to permit air intake to bypass the normal condenser of a closed system oven for low air resistance required for rapid venting. 
         [0021]    The oven may include a handle for opening the door and a door sensor detecting movement of the handle or door indicating a desire by a user to fully open the door, and a computer may activate the fan of the filter system to move air from the cooking volume upon detecting movement of the handle or door indicating a desire by a user open the door. 
         [0022]    It is thus a feature of at least one embodiment of the invention to accommodate unscheduled needs to open the door by providing venting on a post-hoc basis. 
         [0023]    In one embodiment, the oven may include a lock for holding the door closed and the computer may retain the lock in a locked position holding the door closed for a predetermined venting time after detection of movement of the handle or door indicating a desire by a user by a user to open the door. 
         [0024]    It is thus a feature of at least one embodiment of the invention to provide a method of guaranteeing complete venting before the door is opened on an unscheduled basis. 
         [0025]    The filter system may be in a housing without openings to the outside air through which air may be drawn into the filter system. 
         [0026]    It is thus a feature of at least one embodiment of the invention permit passive venting of the exhaust channel without promoting filter bypass. 
         [0027]    The filter system includes at least one filter medium and the fan is positioned after the filter medium to draw air through the filter medium. 
         [0028]    It is thus a feature of at least one embodiment of the invention to provide improved airflow through the use of the fan other than convection fan in the oven and to position that fan in a manner shielded from cooking fumes by the filter media. 
         [0029]    The filter system may include a grease filter and an activated carbon filter. 
         [0030]    It is thus a feature of at least one embodiment of the invention to reduce both grease fumes and odors. 
         [0031]    The activation of the fan may increase the airflow through the filter system to greater than 40 cubic feet per minute. 
         [0032]    It is thus a feature of at least one embodiment of the invention to provide a rapid venting of the oven cavity that does not unduly interfere with cooking of the food. 
         [0033]    The oven may include an airflow sensor detecting airflow through the filter when the fan is on and storing a value of airflow when the fan is on. 
         [0034]    It is thus a feature of at least one embodiment of the invention provide a filter clogging signal available at all times even though the fan may only operate at the very end of the cooking schedule. 
         [0035]    The computer may prevent operation of the heater before commencing the predetermined cooking schedule when a previously stored value of airflow indicates a clogging of the filters. 
         [0036]    It is thus a feature of at least one embodiment of the invention to permit a determination of filter quality before commencing the cooking schedule even though the fan is not operating. 
         [0037]    The oven may further include a filter medium detection switch indicating a presence of filter medium in the filter system and the computer may prevent operation of the heater when the filter medium detection switch indicates the filter medium is not present in the filter system. 
         [0038]    It is thus a feature of at least one embodiment of the invention to prevent bypassing of clogged filter media by removal of the filter media. 
         [0039]    The oven may include a steam generator generating steam from, a source of introduced water and/or may include a convection fan for circulating heated air within the interior volume. 
         [0040]    It is thus a feature of at least one embodiment of the invention to provide a ventless fume hood suitable for combination type ovens. 
         [0041]    The filter system may include a steam filter providing a steam condensing medium. 
         [0042]    It is thus a feature of at least one embodiment of the invention to provide a ventless fume hood suitable for reducing the escape of steam into the kitchen area. 
         [0043]    These particular objects 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 
         [0044]      FIG. 1  is a simplified perspective view of a combination oven suitable for use with the present invention showing a housing having an openable door to reveal a cooking volume and showing a user interface on a front surface of the oven and further showing a ventless fume hood attached to the top of the oven; 
           [0045]      FIG. 2  is a section along line  2 - 2  of  FIG. 1  showing internal filters and vent fans of the ventless fume hood and showing an internal convection fan, heater unit, and condenser unit of the oven and further showing motorized intake and exhaust dampers according to one embodiment of the present invention as well as an expanded cross-sectional view of the condenser unit; 
           [0046]      FIGS. 3   a  and  3   b  are a vertical elevational cross-sectional view and a perspective view of the exhaust damper of  FIG. 2 ; 
           [0047]      FIGS. 4   a  and  4   b  are figures similar to those of  FIGS. 3   a  and  3   b  of the intake damper of  FIG. 2 ; 
           [0048]      FIG. 5  is a timing diagram and schematic representation of the oven as it operates according to a program executed by the oven, the program controlling the vent fan and dampers according to a cooking schedule in which the dampers remain open; 
           [0049]      FIG. 6  is a figure similar to that of  FIG. 5  showing the timing implemented by the program during a cooking schedule in which the dampers remain closed for closed-mode cooking; 
           [0050]      FIG. 7  is a figure similar to the timing diagrams of  FIGS. 5 and 6  showing operation of the program during unexpected door opening during the cooking schedule; 
           [0051]      FIG. 8  is a flowchart of the program of the oven implementing the timings of  FIGS. 5-7 ; 
           [0052]      FIG. 9  is a flowchart of the program implementing a response to an unexpected door opening a  FIG. 7 ; 
           [0053]      FIG. 10  is a fragmentary detail of a filter system similar to that of  FIG. 1  showing the addition of a water bath steam filter; and 
           [0054]      FIG. 11  is a figure similar to that of  FIG. 10  showing the addition of a water spray steam filter. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Oven 
       [0055]    Referring now to  FIG. 1 , a multi-mode oven  10  suitable for use with one embodiment of the present invention may provide a housing  12  defining a cooking volume  14 . Sidewalk of the cooking volume  14  may present rack supports  11  holding conventional cooking racks for supporting pans or trays of food. 
         [0056]    The cooking volume  14  may be accessed through a door  16  connected by a hinge at one vertical side of the cooking volume  14 . The door  16  may close over the cooking volume  14  during the cooking operation as held by a latch assembly  15  (visible on the door  16  only). In the closed position, the door  16  may substantially seal against the cooking volume  14  by compressing a gasket  17  surrounding an opening of the cooking volume  14  in the housing  12 . An optional electrically actuable lock  39  may he positioned near the door  16  in the housing  12  to electrically lock or unlock the door as will be discussed. The latch assembly  15  may be released by a handle  13  whose activation may be detected by a switch  38 . 
         [0057]    At one side of the cooking volume  14 , the housing  12  may support a control panel  22  accessible by a user standing at a front of the oven  10 . The control panel  22  may provide conventional electronic controls such as switches, buttons, and/or a touchscreen or the like that may receive oven control data from the user including a cooking schedule as will be described below. 
         [0058]    Referring now also to  FIG. 2 , positioned within the housing  12  and communicating with the cooking volume  14  is a motor-driven convection fan  18  directing a stream of air across a heater element  20  into the cooking volume  14 . The heater element  20  may be an electric heating element or a heat exchanger receiving heat from a gas flame or the like and may surround the convection fan  18 . 
         [0059]    In one embodiment, steam may be produced by a valve-controlled water jet  19  directing a spray of water on the fan  18  and the heater element  20  proximate to the fan  18 . Alternatively, steam may be provided by a separate boiler  21  having a dedicated heater element  23  and communicating with the cooking volume  14 . 
         [0060]    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. 
         [0061]    Referring still to  FIG. 2 , a bottom wall  31  of the cooking volume  14  may provide a drainpipe  25  extending downwardly from the bottom wall  31  to a condenser chamber  30  positioned beneath the bottom wall  31 . The drainpipe  25  may extend vertically (as shown) or may extend horizontally for a short distance before or after it is received within the condenser chamber  30 . 
         [0062]    in either case, the drainpipe  25  allows steam and water vapor to enter the condenser chamber  30  which provides a generally enclosed box whose upstanding sidewalls retain a pool of water having a water level  36 . The lower end of the drainpipe  28  passing into the condenser chamber  30  stops above the bottom wall  33  and above a water level  36 . 
         [0063]    The condenser chamber  30  may in turn communicate generally with a first electronically controllable exhaust damper  24  through either of a bypass port  26  or a condenser port  27  of the exhaust damper  24  passing through an upper wall of the condenser chamber  30 . The motorized exhaust damper  24  connects with an exhaust pipe  29  venting into a filter unit as will be described below. The exhaust damper  24  operates to determine whether greasy fumes and odor exiting from the cooking volume  14  must pass through the pool of water and out the condenser port and therefore rise to a certain level of pressure necessary for that passage or may bypass the water entirely through the bypass port  27  for low back-pressure venting of the cooking volume  14 . 
         [0064]    A second electronically controllable intake damper  32  is positioned with its exhaust port  34  near the fan  18  to permit outside air to be drawn into the cooking volume  14  from an intake pipe  35  extending to the external atmosphere outside the housing  12 . In this regard, the exhaust port  34  of the intake damper  32  will be in a low-pressure region of the cooking volume  14  when the fan  18  is operating. Conversely, the drainpipe  25  feeding the ports  26  and  27  will be in a high-pressure region of the cooking volume  14  (when the fan  18  is operating) having a higher pressure than the low-pressure region. In this way when the motorized dampers  24  and  32  are open, air is actively drawn from the outer atmosphere into the cooking volume  14  through intake damper  32  and exhausted through drainpipe  25 , condenser chamber  30 , and exhaust damper  24  out of bypass port  27 . It will be appreciated generally, therefore, that closing the motorized intake damper  32  and motorized exhaust damper  24  allows the oven  10  to operate in a conventional closed-system state to provide for high humidity, low heat loss, and low flavor transfer. Conversely, opening motorized dampers  24  and  32  allows the oven  10  to operate in an open state providing low humidity. It will be appreciated that the motorized dampers  24  and  32  may be operated according to a cooking schedule to cyclically open and close to provide for gradations between these two operating point extremes. 
         [0065]    Referring to  FIGS. 1 and 2 , a controller  37  within the housing  12  may receive user input data from the control panel  22  for control of the oven  10  including, for example, cooking schedule. As will be discussed in greater detail below, the controller  37  generally provides an electronic computer executing a program stored in computer memory to control the heater element  20 , fan  18 , and the water jet  19 , and the motorized dampers  24  and  32 , turning the latter on and off as necessary to implement a particular cooking schedule. The controller  37  further communicates with electric locks  39 , the door handle switch  38  and with various elements of the ventless hood as will be discussed below. The cooking schedule may provide for a fixed cooking time (e.g. 30 min.) or predetermined cooking temperature (for example 180° F.) typically as determined by a thermal probe  41  communicating with the controller  37 . 
         [0066]    As shown in  FIG. 2 , the condenser chamber  30  may provide for an overflow port  42  that generally connects to the sanitary sewer line but with some venting arrangement which allows the escape of gases. For example, the exhaust port  34  may discharge onto a floor drain or the like. Water in the condenser chamber  30  may be maintained at a cool temperature by a freshwater inlet  44  adding makeup water through a valve (not shown) also under the control of the controller  37  which may further communicate with a temperature gauge  46  so that additional water is added through the inlet  44  only when the temperature of the existing water rises above a certain amount. As water is admitted through inlet  44 , excess water drains out through the overflow port  42  which provides an overflow lip  47  defining the water level  36 . Steam passing through the drainpipe  25  may also pass into a steam collection port  48  that may recirculate back to the cooking volume  14 . The steam collection port  48  may hold a temperature sensor (not shown) communicating with the controller  37  which may be used to provide steam temperature information useful for control of the oven  10 . 
         [0067]    A variation on this design is shown in U.S. patent application Ser. No. 13/306,687 filed Nov. 29, 2011, entitled “Grease Handling Apparatus for Closed-system Oven” assigned to the same assignee as the present invention and hereby incorporated by reference. 
         [0068]    Importantly, the internal volume of the condenser chamber  30  is divided by a vertical baffle plate  40  extending down from an upper wall of the condenser chamber  30  below the water level  36  but above the bottom of the condenser chamber  30 . This baffle plate  40  provides two distinct paths of water vapor flow from the cooking volume  14  depending on a state of operation of the exhaust damper  24 . In a first path, water vapor passing into the condenser chamber  30  through the drainpipe  25  may pass out of a bypass port  26  without flowing through the water. Alternatively, in a second path, water vapor passing into the condenser chamber  30  through drainpipe  25  may flow through the water and beneath the vertical baffle plate  40  to condense any steam in that flow. This latter path introduces some back pressure resulting from a resistance to gas flow through the water and therefore tends to retain moisture within the cooking volume  14  while providing a release of excess pressure only. 
         [0069]    Accordingly, the state of operation of the exhaust damper  24  may provide either a low resistance direct venting of the cooking volume  14  to the outside atmosphere (as will be used for open-state operation) or a higher resistance indirect venting of the cooking volume  14  through the water of the condenser chamber  30  (as will be used for closed-state operation). 
         [0070]    Referring now to  FIG. 3 , in this regard, motorized exhaust damper  24  may provide for a generally enclosed manifold  50  joining the intake ports  26  and  27  and exhaust pipe  29 . The housing may be divided by a flapper valve  52  comprising a valve plate  54  pivoting at pivot point  56  attached between an upper edge of the valve plate  54  and a lower surface of an upper wall of the manifold  50 . The valve plate  54  is normally pressed against a valve seat  58  by a biasing element  60  such as a weight. When so biased against the valve seat  58 , the intake port  26  is isolated from the port  27  and an exhaust pipe  29 . 
         [0071]    A gearmotor  61  having motor leads  62  receiving control signals from the controller  37  may drive a hub  64  extending into the manifold  50  having diametrically opposed radially extending fingers  66  attached to rotate with the hub  64 . In one direction of rotation, indicated by an arrow in  FIG. 3 , one of the fingers  66  may press against the valve plate  54  to lift it away from the valve seat  58  against the biasing element  60  to allow flow of water vapor through port  26  to exhaust pipe  29 . This flow will be preferred over a flow through condenser port  27  because of the lack of back resistance from the water in the condenser chamber  30 . When the gearmotor  61  continues rotation, the finger  66  is removed from the valve plate  54  allowing it to close under the influence of the biasing element  60 . At this point, water vapor must flow primarily through port  27  to reach exhaust pipe  29  and thus through the water of the condenser chamber  30 . 
         [0072]    The gearmotor  61  may have a cam  67  communicating with a limit switch  68  or other sensor allowing the controller  37  to accurately control the finger  66  to stop motion with the valve plate  54  alternately at an open and closed position corresponding to an open and closed system state of the oven as will be further described. 
         [0073]    Referring now to  FIG. 4 , the motorized intake damper  32  may likewise provide a manifold  70  divided internally by valve plate  72  pivoting at its upper edge about pivot  74  attached to an inner upper surface of the manifold  70 . The valve plate  72  is normally held against a valve seat  76  as biased by biasing element  78 , in this case depicted as a spring. In a manner similar to that described above, fingers  80  attached to a hub  82  driven by a gearmotor  84  may control opening of the valve plate  72  under the control of the controller  37 . For the purpose of this control, the gearmotor  84  may include a cam  86  and limit switch  88  providing signals to the controller  37 . In motorized intake damper  32 , the valve plate  72 , when closed, separates the exhaust port  34  from the intake pipe  35 , and when open allows free flow of gas between the intake pipe  35  and exhaust port  34 . 
       Filter System 
       [0074]    Referring still to  FIGS. 1 and 2 , a ventless hood  90  may be positioned on top of the housing  12  of the oven  10 . The ventless hood  90  may provide a housing  97  having a front wall  92  without intake vents communicating directly with the outside atmosphere. The front wall  92  may be temporarily moved or removed for access to the internal elements of the ventless hood  90 . 
         [0075]    Intake pipe  35  may project upward through the housing  12  into the volume of the housing  97  to receive intake air through a vent  94  in a rear wall  96  of the housing  97 . Exhaust pipe  29  may also project upward through the housing  12  to then pass through a vertical divider plate  98  in the housing  97 , the latter separating the space within the housing  97  receiving intake pipes  35  and exhaust pipe  29  from a filter portion of the ventless hood  90 . 
         [0076]    Air exhausted through the exhaust pipe  29  entering the filter portion of the ventless hood  90  passes through a grease filter  100  and then through an activated carbon filter  102 , the combination providing filter media removing grease and odors from that air. The air from the exhaust pipe  29  may be moved through the filter media solely by action of the fan  18  within the oven  10  in a passive filtration mode. Alternatively, in an active filtration mode, air from the exhaust pipe  29  may be moved through the filter media by a combination of fan  18  and one or more ventless hood fans  104  position downstream from the carbon filter  102 . In the active filtration mode, an air changeover of the cooking volume  14  of approximately 65 cubic feet per minute is obtained. Air passing through the filter media and passed through the hood fans  104  is expelled through a rear vent  106  in rear wall  96 . 
         [0077]    An air flow gauge or differential pressure gauge  108  may be positioned within the housing  97  to gauge airflow through the filters  100  and  102  and to provide a signal indicating whether those filters  100  and  102  need to be replaced as can be done through the front wall  92 . Replacement is indicated when the pressure drop across the filters  101  and  102  rises above a predetermined amount when the hood fans  104  are active or airflow through the filters  101  and  102  drops below a predetermined amount when the hood fans  104  are active. 
         [0078]    Mechanical switches  110  and  112  are positioned abutting the filters  101  and  102  to be activated when filters  100  and  102  are in place. These switches  110  and  112  provide a signal allowing prevention of operation of the oven  10  when both of the filters  101  and  102  are not in place as will he discussed below. Each of the mechanical switches  110 ,  112 , pressure gauge  108 , and fans  104  communicates with the controller  37  to be controlled or read by the controller  37  according to a program  114  executing on controller  37 . 
         [0079]    Referring no to  FIGS. 2 and 8 , in operation, the program  114  executing on the controller  37  may receive a cooking schedule as indicated by process block  116  entered by user of the oven. This cooking schedule provides a schedule that may be as simple as a cooking time (being a time duration after which the oven turns off), a set of shelf times (being different time durations for different shelves of the oven) or a cooking temperature (being a temperature experienced by the probe  41 ). The cooking schedule may variously control operation of the heater element  20 , opening of the dampers  24  and  32 , and control of the water jet  19  according to the time, temperature, humidity or the like. Such cooking schedules may be entered by hand or may be selected from a menu of prestored such cooking schedules according to techniques known in the art. 
         [0080]    Once the cooking schedule has been entered, the user may start the cooking process as determined by decision block  118 . At this time as indicated by decision block  120 , the program  114  checks to see if the filter of the ventless hood  90  is in proper operating condition, meaning that filters  101  and  102  are in place and are not clogged. If the filters  101  and  102  are not functioning, an error messages is indicated at process block  122  and starting of the oven  10  is prevented until proper maintenance of the filters  101  and  102  is performed. 
         [0081]    Determination as to whether the filter is clogged may be based on a previous time during which the oven fan  104  was operating in a previous cooking cycle or may be determined by a momentary operation of the oven fan  104  before the oven  10  has heated as measured by pressure gauge  108  (shown in  FIG. 2 ). 
         [0082]    If the filter is in functional condition, the program  114  executes the entered cooking schedule in which the control of the temperature of the oven  10  and humidity of the oven  10  and the like is performed as indicated by process block  124 . Optionally at this time or a few minutes after beginning of the cooking schedule, the door of the oven  10  is locked as indicated by process block  126  using lock  39  shown in  FIG. 1 . 
         [0083]    The cooking schedule proceeds using, for example, a clock to increment through a schedule of temperatures, humidities and the like according to a time function of the cooking schedule or during which temperature of probe  41  is monitored. At decision block  128  an imminent ending of the schedule is checked. For example, when the cooking schedule is a predetermined cooking time, decision block  128  may detect when a predetermined time before the end of the cooking schedule has occurred. This predetermined time is selected to be sufficient to vent the cooking volume  14 , for example, 25 seconds to 1 minute and 45 seconds. Alternatively, when the cooking schedule is a predetermined temperature, decision block  128  may detect when a temperature sensed by the probe  41  is a predetermined number of degrees, for example 5° F., before the end of the cooking schedule temperature. When the cooking schedule includes a number of different times and/or conditions, for example, for different shelves of the oven  10 , this process may be repeated appropriately for times preceding the termination of each cooking schedule. 
         [0084]    When decision block  128  detects an imminent conclusion of the cooking schedule, as indicated by process block  130 , dampers  24  and  32  are open irrespective of the setting of the cooking schedule. The hood fan  104  is then started at process block  132 . Normally the hood fan  104  does not operate prior to this time and remains off to save power and to prevent interference with the cooking process. 
         [0085]    During the running of the hood fan  104 , the filter media may be checked for clogging as indicated by process block  134  using the pressure gauge  108  which indicates clogging of the filters only when the filter fan  104  is operating. As noted above, this check may be used and stored for the next time decision block  120  is reached and will normally provide a maintenance reminder to the user at this time. 
         [0086]    At decision block  136 , the completion of the cooking schedule is evaluated according to a cooking time having fully elapsed or proper cooking temperature having been reached. While the completion of the cooking schedule does not complete, the temperature of the oven may be maintained although steam may be deactivated. This approach allows the invention to accommodate shelf timers in which some food will be removed and other food will remain for additional cooking. If the cooking schedule is complete or a part of the cooking schedule is complete, as in the case of different shelf timers, a signal is provided to the user in the form of a light or sound as indicated by process block  138 . At this time or slightly before as indicated by process block  140  the door may be unlocked if it was previously locked. 
         [0087]    If the completion of the schedule of decision block  136  completes an entire schedule as determined at decision block  142 , the oven heater is turned off as indicated by process block  146 . The dampers  24  and  32  may be held open for a brief cool down interval while the fan  104  continues to operate. 
         [0088]    If the completion of the schedule of decision block  136  is only a portion of the schedule, then at decision block  148  a reclosure (opening then closing of the door) is detected upon which the program returns to decision block  136  for completion of the next cooking schedule portion. Before reclosure of the door, the oven heater element  20  may be temporarily turned off and dampers  24  and  32  held open and fan  104  may continue to operate. After the doors closed, control of the dampers  24  and  32  may be according to the cooking schedule (generally closed) and the fan  104  turned off and the program loops back to process block  124 . 
         [0089]    Referring now to  FIG. 5 , operation of the program  114  during an open cycle cooking schedule (or an open cycle portion of the cooking schedule) may open dampers  24  and  32  during the cooking schedule, for example, to promote browning and low humidity cooking. The open dampers  24  and  32  will provide a low flow rate through the filters  100 ,  102  caused by operation of the convection fan  18  at about 15 cubic feet per minute as depicted by schematicized oven diagram A. At this time the fan  104  is off. This low flow rate does not unduly interfere with uniform temperature control in the cooking volume  14 . 
         [0090]    At vent initiation time  150  (sensed by decision block  128  of  FIG. 8 ) the hood fan  104  is turned on as indicated in schematicized oven diagram B providing more than approximately 40 cubic feet per minute of exhaust and typically 65 cubic feet per minute of exhaust of the cooking volume  14 , being the combined effect of convection fan  18  and ventless hood fan  104 . 
         [0091]    Referring now to  FIG. 6 , in contrast, in a closed cycle cooking schedule (or a closed cycle portion of the cooking schedule) that normally has the dampers  24  and  32  closed, for example, for steam cooking or the like, prior to vent initiation time  150 , dampers  24  and  32  may be closed and no filtering performed. At the vent initiation time  150 , the dampers  24  and  32  are open irrespective of the schedule cooking schedule and the hood fan  104  is turned on to provide rapid exhaust of the cooking volume  14 . 
         [0092]    Referring now to  FIGS. 7 and 9 , after the oven door is optionally locked per process block  126 , an attempt to open the door may be nevertheless detected at decision block  160 . If there is no attempt to open the door handle  13 , the program proceeds to decision block  128  as has been described previously with respect to  FIG. 8 . If a door release is attempted, for example, at a time  164 , the program  114  proceeds to process block  162  and the vents are opened (regardless of the schedule) and the hood fan  104  started at process block  165 . A vent time is imposed as indicated by decision block  166  generally equal in length to the pre-venting time  151  for example, approximately 60 seconds. At that time, if the door was previously locked, the door is unlocked per process block  168 . The hood fan  104  may be turned off at this time or remain on to limit the expulsion of hot air from the oven  10  and to allow the pre-venting time  151  to be made as short as possible. At decision block  170 , reclosure of the door may be detected (e.g. the door  16  being opened and then reclosed). Upon such reclosure, the hood fan  104  is turned off as indicated by process block  172  and the lock optionally reestablish at process block  174  whereupon the program returns to decision block  128 . In this way, unexpected opening of the door may be accommodated with minimal escape of cooking fumes. 
         [0093]    Referring now to  FIG. 10 , in one embodiment, the ventless hood  90  may include a steam filter  180  in series with the grease filter  100  and odor filter  102  and placed before the fan  104 . In one embodiment, the steam filter  180  provides for a contained water bath  182  with exhaust pipe  29  extending upward through the water level  184  of the water bath  182  on a first side of a downwardly extending partition  186 . The partition  186  is constructed so that oven fumes  188  passing out of exhaust pipe  29  must pass downward through the water bath  182  beneath the partition  186  in order to exit through an exit port  190  of the steam filter  180  to then be received by the grease filter  100 . 
         [0094]    The steam filter  180  may provide a water inlet  192  for introducing water into the water bath  182 , an overflow port  194  for limiting the height of the water bath  182  to water level  184 . And a temperature sensor  198  for measuring the temperature of the water bath  182 . In a manner similar to that described above with respect to the condenser chamber  30 , a valve system (not shown) may add water through the water inlet  192  when the temperature of the temperature sensor  198  rises above a predetermined amount. This introduced water flushes heated water out the overflow port  194  to lower the temperature of the water bath  182  for effective steam condensation. The overflow port  194  may lead via an internal duct to an exit also used by the condenser chamber  30  ultimately leading to a floor drain or the like. The height of the water level  184  is set so that a pressure required for oven fumes  188  to pass through the water bath  182  can be achieved by operation of the convection fan  18  alone without operation of fans  104 . 
         [0095]    Referring now to  FIG. 11 , in an alternative embodiment the steam filter  180  may provide a mist spray nozzle  200  attached to the water inlet  192 . The spray nozzle  200  provides a high surface area spray mist  202  through which oven fumes  188  must pass in exiting exhaust pipe  29  and traveling to exit aperture  190 . A drain port  204  may be provided in the lower wall of the steam filter  180  to capture excess water from the mist  202  and condensed steam. No partition  186  or water bath  182  is necessary in this embodiment although the two techniques may be combined. 
         [0096]    Referring momentarily to  FIG. 8 , operation of the steam filter  180  of  FIG. 10  in terms of water temperature monitoring may be active only when the oven is operating between process block  116  and process block  146 . The steam filter  180  of  FIG. 11  may likewise be activated only during this time or may be activated in terms of providing the mist  202  only when the hood fan  104  is active per process block  132  or process block  165  of  FIG. 9 . 
         [0097]    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”, and “below” 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. 
         [0098]    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. 
         [0099]    References to “a control board” and “a processor” can be understood to include one or more microprocessors 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. 
         [0100]    It is specifically intended that the present invention not be limited to the embodiments and illustrations contained herein and the claims should be understood to 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. All of the publications described herein, including patents and non-patent publications, are hereby incorporated herein by reference in their entireties.