Patent Document

BACKGROUND OF THE INVENTION  
         [0001]    This invention relates generally to cooking appliances, and more specifically to ovens.  
           [0002]    Many known ovens include a fan for circulating air within the oven. For example, a typical convection oven includes a convection fan which operates in a single direction to circulate air within the oven during convection cooking. Such air circulation facilitates cooking by causing air to flow over, and to be heated by, the convection cooking element.  
           [0003]    Cooking with such one directional fans, however, may result in uneven cooking. Specifically, the air flow path within an oven cooking cavity typically is not dynamic, i.e., does not change during cooking. For example, the fan is securely fixed to a wall of the cooking cavity and hot air from the cooking element typically is directed along a same flow path. As a result, the relative position of food within the cooking cavity with respect to the flow path impacts the evenness of cooking. For example, if a portion of the food is directly in the flow path of air from the convection fan, such food portion may cook more quickly than another portion of the food that is not in the direct air flow path. Uneven cooking can cause variation in browning and a darkening around the edges in baked products.  
           [0004]    At least one known oven includes a plurality of fans and by reversing rotation of the fans, the air flow pattern within the oven cooking cavity is altered. Requiring multiple fans, including multiple fan motors for driving the fans, increases the cost of the ovens and may be cost prohibitive.  
         BRIEF DESCRIPTION OF THE INVENTION  
         [0005]    In one aspect, an oven includes an oven cavity, at least one heat source for supplying energy to the cavity, and an oven controller operationally coupled to the heat source. The oven controller is configured to accept data regarding a number of racks, and control the at least one heat source based upon the accepted data.  
           [0006]    In another aspect, an oven includes an oven cavity, at least one heat source for supplying energy to the cavity, and at least one fan assembly for circulating air in the cavity. The fan assembly includes a fan motor, a shaft extending from the motor, and a fan coupled to the shaft. The oven also includes an oven controller operationally coupled to the fan motor. The oven controller is configured to energize the fan motor during a cook cycle, de-energize the fan motor during the cook cycle, and re-energize the fan motor during the cook cycle.  
           [0007]    In a still further aspect, a method for controlling at least one heat source of an oven is provided. The method includes receiving data regarding a number of racks and controlling the at least one heat source based upon the received data. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0008]    [0008]FIG. 1 is a front view of an oven.  
         [0009]    [0009]FIG. 2 is a cut away view of the oven shown in FIG. 1.  
         [0010]    [0010]FIG. 3 is an exploded view of the convection assembly shown in FIG. 2.  
         [0011]    [0011]FIG. 4 is a top view of the fan shown in FIG. 3.  
         [0012]    [0012]FIG. 5 is a perspective view of the fan shown in FIG. 4.  
         [0013]    [0013]FIG. 6 is a front view of the oven control user interface shown in FIG. 1.  
         [0014]    [0014]FIG. 7 is a block diagram of an oven.  
         [0015]    [0015]FIG. 8 illustrates an exemplary control algorithm for the oven shown in FIG. 1.  
         [0016]    [0016]FIG. 9 illustrates the cycling of the oven shown in FIG. 1 in a convection bake multiple rack mode.  
         [0017]    [0017]FIG. 10 is a perspective view of a blocking fan.  
         [0018]    [0018]FIG. 11 is a plan view of the blocking fan shown in FIG. 10.  
         [0019]    [0019]FIG. 12 is a perspective view of a blocking fan.  
         [0020]    [0020]FIG. 13 is an exploded view of convection assembly shown in FIG. 2 with the blocking fan shown in FIG. 12 included. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0021]    [0021]FIG. 1 is a front view of an oven  10  including a door  12  and an oven control user interface  14 . Door  12  includes a window  16  and a handle  18 . Oven control user interface  14  includes a plurality of input devices  20  and a display  22 , which are described in greater detail below. Oven  10  is illustrated as a built-in wall oven. The oven control described herein, however, can be utilized in connection with many other types of ovens such as free-standing ovens, drop-in ovens, slide ovens, and speed cooking ovens. In one embodiment, oven  10  is a convection microwave oven. Generally, the control described herein can be used in connection with any convection oven that includes a convection fan. Such ovens are commercially available from the GE Appliances business of General Electric Company, Louisville, Ky.  
         [0022]    [0022]FIG. 2 is a cut away view of oven  10  illustrating in schematic form a portion of an oven cavity  24  formed by a plurality of oven walls  26 , a back wall  28 , and door  12  (shown in FIG. 1). A plurality of heating segments  30  form a baking element  32  (a heat source) and a plurality of heating segments  34  form a broiling element  36  (a heat source). A convection assembly  38  is mounted on back wall  28  of oven  10 . In an exemplary embodiment, broiling element  36  is a 3600 watt (W) element and baking element  32  is a 2800 W element.  
         [0023]    [0023]FIG. 3 is an exploded view of convection assembly  38 . Convection assembly  38  includes a fan assembly  39 . Fan assembly  39  includes a motor  40  including a shaft  42  extending from motor  40 , and a fan  44  mounted to shaft  42 . Convection assembly  38  also includes a convection element  46  (a heat source) and a cover member  48 . In an exemplary embodiment, convection element  46  is a 2500 W element. In an alternative embodiment, convection assembly  38  does not include a convection element  46  and oven  10  is a pseudo-convection oven. Cover member  48  includes a base portion  50  and a wall portion  52  extending obliquely radially inward from base portion  50  to a rim portion  54 . Rim portion  54  extends substantially planer to an inner wall portion  56  which extends obliquely radially inward toward base portion  50  to a substantially planer face portion  58 . Wall portion  52  includes a plurality of openings  60 . In one embodiment, openings  60  are substantially rectangular shaped. Rather than being rectangular shaped, openings  60  can have many other different geometric shapes such as circular. Face portion  58  includes a plurality of elongated openings  62 . Selected openings  60  can be partially or completely covered to allow for a tailoring or tuning of air flow within the cooking cavity.  
         [0024]    Motor  40  is mounted to an oven rear wall such that shaft  42  extends through an opening in rear cavity wall  28  and into cavity  24  (shown in FIG. 2). Fan  44  is mounted to shaft  42  such that fan  44  is positioned within cavity  24 . Convection element  46  is mounted to rear cavity wall  28  and connected to an energy source (not shown). In the example embodiment, convection element  46  extends circumferentially around fan  44 . Cover member  48  is attached to back wall  28  and shields convection element  46  and fan  44 .  
         [0025]    In an example embodiment, motor  40  is a permanent split capacitor (PSC) motor. Motor  40  is reversible in that motor  40  can alternately drive fan  44  in a clockwise and in a counter-clockwise direction. PSC motors are commercially available, such as from Plaset S.p.A., 10024 Moncalieri (TO), Italy. In the example embodiment, motor  40  is a two pole PSC motor and is configured to rotate shaft  42  at speeds up to 3600 revolutions per minute (rpm&#39;s) in both a clockwise direction and a counter-clockwise direction, and has a 6μFarads (F) capacitor. In an alternate embodiment, motor  40  is a reversible motor other than a PSC motor.  
         [0026]    [0026]FIG. 4 is a front view of fan  44  including a plurality of radially extending portions  64  extending from a circular central section  66 . Central section  66  includes an opening  68  having a flat portion  70  and an arcuate portion  72  facilitating keying fan  44  with shaft  42 . Each radially extending portion  64  includes a fan blade  74  that extends radially outward, is substantially planar, and pushes air when fan  44  is rotated.  
         [0027]    [0027]FIG. 5 is a perspective view of fan  44 . Each fan blade  74  includes an outer edge  75 . In an exemplary embodiment, fan  44  is fabricated from a single piece of sheet steel. Outer edges  75  are cut from the single piece of sheet steel and portions of the single sheet of steel are folded along a line  76  to form fan blades  74 , radially extending portions  64 , and a plurality of voids  77 .  
         [0028]    [0028]FIG. 6 is a front view of oven control user interface  14 . Various touch sensitive pads  20  allow a user to select various cooking parameters such as convection roast and convection bake. The user can also select non-convection settings such as bake, broil, proof, and warm. Additionally, the user can use a numeric keypad  78  to enter numerical data relating to temperature, cook time, clock time, and kitchen timer. Display  22  includes a multi light  80 . When the user selects convection bake a first time, multi light  80  is illuminated indicating that oven  10  is in multiple rack mode as explained in detail below. When the user selects convection bake a second time, multi light  80  is not illuminated indicating that oven  10  is in single rack mode as explained below.  
         [0029]    The user can toggle between single rack mode and multiple rack mode. In an alternative embodiment, and rather than relying on user input regarding selection of the number of racks on which food is located, at least one sensor senses whether one rack or multiple racks (e.g., by pressure or weight on a rack, or by sensing the presence of baking ware) are being used and provides an indication of rack mode to an oven controller automatically. Additionally, multiple rack mode need not be the first mode. For example, when the user selects convection bake a first time, multi light  80  is not illuminated indicating that oven  10  is in single rack mode, and when the user selects convection bake a second time, multi light  80  is illuminated indicating that oven  10  is in multiple rack mode.  
         [0030]    [0030]FIG. 7 is a block diagram of oven  10  including an oven controller  82 . Oven controller  82  is electrically connected to oven control user interface  14  and fan  44 . In addition, oven controller  82  is electrically connected to baking element  32 , broiling element  36 , and convection element  46 . Oven controller  82  receives inputs from oven control user interface  14  and controls fan  44 , baking element  32 , broiling element  36 , and convection element  46  as described herein.  
         [0031]    [0031]FIG. 8 illustrates an exemplary algorithm for controlling operation of the oven  10  in response to various user selections. For example, when convection bake is selected in multiple rack mode as explained above, and a temperature between 170 degrees Fahrenheit (F.) and 550° F. is selected, fan  44  is rotated clockwise for twenty seconds and then de-energized for ten seconds before being energized in the counter clockwise direction for forty seconds. Fan  44  is then de-energized for ten seconds and then re-energized for twenty seconds in the clockwise direction starting the cycling over again. In addition to cycling fan  44 , convection heating element  46  is cycled on for periods of time equal to integral minutes (i.e., X minutes where X in an integer). For example, the temperature within cavity  24  is measured continuously and when the temperature is about 15° below (or less than 15° below) the temperature set by the user, heating element  46  is energized supplying heat to cavity  24 . The temperature continues to be measured and when the temperature in cavity  24  is about 15° above (or greater than 15° above) the user specified temperature, heating element  46  is de-energized. The cycling of fan  44  is independent of the temperature of cavity  24 . Although the illustrated embodiment uses a 15° temperature range which has been empirically derived to provide satisfactory cooking results, other temperature ranges are also useful, and accordingly, in other embodiments, a range other than 15° is used.  
         [0032]    Additionally, when convection bake is selected in single rack mode as explained above, and a temperature between 170° F. and 550° F. is selected, fan  44  is rotated clockwise for three minutes and then de-energized for ten seconds before being energized in the counter clockwise direction for three minutes. Fan  44  is then de-energized for ten seconds and then re-energized for three minutes in the clockwise direction starting the cycling over again. In addition to cycling fan  44 , bake element  32  and broil element  36  are cycled on for periods of time equal to integral minutes. For example, the temperature within cavity  24  is measured and when the temperature is about 5° below (or less than 5° below) the temperature set by the user, bake element  32  and broil element  36  are energized supplying heat to cavity  24 . More specifically, bake element  32  is energized for the first 45 seconds of each minute and broil element  36  is energized for the last fifteen seconds of each minute. When bake element  32  is energized, broil element  36  is de-energized, and when broil element  36  is energized, bake element  32  is de-energized. The temperature continues to be measured and when the temperature in cavity  24  is about 5° above (or greater than 5° above) the user specified temperature, bake element  32  and broil element  36  are de-energized. Although the illustrated embodiment uses a 5° temperature range which has been empirically derived to provide satisfactory cooking results, other temperature ranges are also useful, and accordingly, in other embodiments, a range other than 5° is used. Additionally, while an approximate five degree range is maintained when the selected mode is single rack, an approximate fifteen degree range is maintained when the selected mode is multiple rack. The different degree ranges facilitate an even cooking in both rack modes.  
         [0033]    When convection roast is selected, fan  44  rotates counter clockwise continuously. Fan  44  also rotates continuously counter clockwise when a dehydrate mode is selected. When a proof mode is selected all heating sources  32 ,  36 , and  46  are kept de-energized and an oven light (not shown) inside cavity  24  is illuminated. Additionally, in the proof mode, fan  44  is rotated clockwise for one minute and then fan  44  is de-energized for ten minutes. Fan  44  is then energized in the counter clockwise direction before being de-energized for ten minutes before the cycle starts over again.  
         [0034]    [0034]FIG. 9 illustrates the cycling of oven  10  in convection bake multiple rack mode. Convection heating element  46  is energized until cavity  24  reaches about 15° above the desired temperature (325 F.). Convection heating element  46  is de-energized until the temperature falls to about 15° below the desired temperature, at which point heating element  46  is energized again until the temperature is about 15° above the desired temperature. Fan  44  is cycled independent of heating element  46 . The cycling of fan  44  facilitates an evenness of cooking in oven  10 .  
         [0035]    [0035]FIG. 10 is a perspective view and FIG. 11 is a plan view of a blocking fan  50  including a generally circular middle portion  52  including a mounting hole  54 . A plurality of support members  56  extend radially from middle portion  52  to a plurality of arcuate fan sections  58 . Each fan section  58  extends from one support member  56  to another support member  56  and includes a centrally positioned opening  60 . Between each fan section  58  is an open section  62  such that open sections  62  alternate with fan sections  58 . Fan sections  58  extend both radially and axially away from middle portion  52 . Fan sections  58  are also arcuate circumferentially.  
         [0036]    locking fan  50  is positioned within cavity  24  and separate from fan  44 . More particularly, blocking fan  50  is rotatably mounted such that blocking fan  50  is aerodynamically coupled with fan  44 . Blocking fan  50  is not connected to a motor, rather blocking fan is positioned such that when fan  44  rotates causing an air flow within cavity  24 , the air flow caused by fan  44  causes blocking fan  50  to rotate and create dynamically changing air flow patterns within cavity  24 . In an exemplary embodiment, blocking fan  50  is positioned such that mounting hole  50  is axially aligned (but not connected) with shaft  42 . The size of openings  60  and open sections  62  can be varied to create different dynamically changing air patterns.  
         [0037]    During operation of fan  44  in a single direction or any single direction fan, blocking fan  50  rotates in the same direction as fan  44  but at a lower speed than fan  44 . In an alternate embodiment, blocking fan  50  rotates in a direction opposite of fan  44 . Because blocking fan  50  has fan sections  58  and open sections  62 , blocking fan  50  blocks off different portions of the air flow generated by fan  44  as blocking fan  50  rotates to dynamically change the air flow inside cavity  24 . This dynamic changing of the airflow within cavity  24  facilitates an evenness of cooking with oven  10 .  
         [0038]    [0038]FIG. 12 is a perspective view of a blocking fan  70  and FIG. 13 is an exploded view of convection assembly  38  with blocking fan  70  included. Blocking fan  70  includes a central portion  72  and a plurality of support members  74  extending from central portion to a plurality of arcuate fan sections  76 . Each arcuate fan section  76  includes at least one vane  78  defining a vane angle  80 . Although illustrated with four fan sections  76 , in other embodiments, fan  70  has more than and less than four fan sections  76 . In an ex  
         [0039]    During operation of fan  44  in a single direction or any single direction fan, blocking fan  70  rotates to dynamically change the air flow inside cavity  24  as explained with respect to blocking fan  50 . This dynamic changing of the airflow within cavity  24  facilitates an evenness of cooking with oven  10 .  
         [0040]    Accordingly, a reliable cost-efficient oven is provided that provides an evenness in cooking. The evenness is achieved when both a single rack is used and when multiple racks are used to cook food. Additionally, a dynamic airflow is achieved with a single fan motor. In one embodiment, the dynamic air flow is made by reversing the direction of the motor, and, in another embodiment, the dynamic air flow is made with a blocking fan aerodynamically coupled to a single direction fan.  
         [0041]    While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.

Technology Category: 5