AN OVEN

Abstract

An oven (1000) having a body (1002) including a base, a roof, and side walls extending between the base and the roof, the side walls at least partially surrounding a cooking cavity (1030), the oven (1000) including: an impeller assembly (1060) mounted to a first side wall of the oven body, the impeller assembly (1060) including: an impeller (1062) that is rotatable for directing airflow within the cooking cavity (1030); a plurality of air guides (2006) at least partially surrounding the impeller (1062), the air guides (2006) each defining a channel generally extending transversely from a central axis of the impeller (1062); and a pair of thermal elements (2010) located on each side of the impeller (1062), where the air directed from the impeller (1062) travels transversely along the air guide channels (2006), through the thermal elements (2010), and into the cooking cavity (1030).

Description

AN OVEN FIELD OF INVENTION The present invention relates to cooking appliances, such as ovens. In particular, the invention relates to convection systems for ovens. The invention has been developed primarily for use with an oven and will be described hereafter with reference to this application. However, it will be appreciated that the invention is not limited to this particular field of use. BACKGROUND OF THE INVENTION Appliances used to cook food, such as an oven, provide heat circulation around a cooking cavity or chamber in which the food is cooked. There are typically three forms of heat transfer around the cooking chamber: conduction, convection, and radiation. In an oven, food is typically cooked by either convection or radiant heat. Radiant energy from the heating elements cooks the food with direct heat, while convection cooks the food indirectly through the circulation of air from a fan. Oven fans can be used in either convection or fan-assisted mode. A fan-assisted mode utilizes radiant heat from the elements within the cooking cavity, where the fan circulates hot air around the cavity to cook the food. Food cooked in this fan-assisted mode is subject to directing energy from the elements inside the cavity, resulting in centralized browning over a flat surface. Convection oven modes, on the other hand, typically use a heating element located outside the cooking cavity and adjacent to the fan. Hot air is blown throughout the cavity, cooking the food evenly without any radiant heat effect. BRIEF DESCRIPTION OF THE INVENTION It is an objective of the present invention to substantially overcome, or at least improve upon, one or more of the disadvantages of existing arrangements, or at least to provide a useful alternative to existing arrangements. This description describes an oven having a body that includes a base, a roof, and side walls extending between the base and the roof, the side walls at least partially surrounding a cooking cavity. The oven includes: an impeller assembly mounted to a first side wall of the furnace body, the impeller assembly includes: an impeller that is rotary to direct the airflow inside the cooking cavity; a plurality of air guides surrounding at least partially the impeller, the air guides each defining a channel that generally extends transversely from a central axis of the impeller; and a pair of thermal elements located on each side of the impeller, where the air directed from the impeller travels transversely along the air guide channels, through the thermal elements, and into the cooking cavity. The air guides may each include an upper vane and a lower vane; the upper and lower vanes are connected by a support portion to define the channel between them. Air guides can be mounted to an inlet manifold of the impeller assembly. The channel of each air guide can extend transversely to a right side wall or a left side wall of the oven, where the opposing channels create linearly opposite flow paths, and where the air traveling along the opposing channels is subsequently displaced to a front portion of the oven, and then to a rear wall of the oven. Air movement can create two air cells within the cooking cavity; the two air cells have opposite flow paths. Air guides can be positioned between the impeller and the thermal elements, where the thermal elements are separated from the central axis of the impeller and therefore a motor from the impeller assembly, by a distance. Each thermal element may have a generally U-shaped structure defined by two parallel and elongated portions separated or legs connected at their upper ends by a curved portion. The thermal elements may each include at least one mounting portion located toward an upper part of the U-shaped structure adjacent to the curved portion. Preferably, during use, the thermal electromagnetic radiation emitted from each of the thermal elements is reflected into the cavity to provide a visual indication of the oven's operating status. BRIEF DESCRIPTION OF THE FIGURES The preferred embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which: Figure 1 is a schematic isometric view of a first modality of a furnace; Figure 2 is a schematic rear view of an oven door shown in Figure 1; Figure 3 is a schematic isometric view of a baking cavity of the oven shown in Figure 1; Figure 4 is a schematic exploded isometric view of a furnace impeller assembly shown in Figure 1; Figure 5 is a schematic plan view of the drive assembly of Figure 4, partially disassembled; Figure 6 is a schematic isometric view of an interior wall of the furnace shown in Figure 1, the impeller assembly and the installed thermal elements; Figure 7 is a schematic exploded isometric view of another impeller assembly; Figure 8 is a schematic plan view of the impeller assembly shown in Figure 7; Figure 9 is a schematic isometric cross-sectional view of a second type of oven; Figure 10 is a schematic exploded isometric view of the oven shown in Figure 9; Figure 11 is a schematic top view of the airflow in the oven shown in Figure 9; Figure 12 is an additional schematic isometric cross-sectional view of the oven in Figure 9; Figures 13A and 13B are schematic isometric views of the thermal elements of the furnace shown in Figure 9; Figure 13C is a schematic side cross-sectional view of the oven shown in Figure 9; Figure 14A is a schematic isometric view of the air guides or furnace vanes shown in Figure 9; Figure 14B is a schematic exploded isometric view of a furnace impeller shown in Figure 9; Figure 15 is a schematic isometric view of a third modality of an oven in a closed configuration; Figure 16 is a schematic isometric view of the oven shown in Figure 15 in an open configuration; Figure 17 is an additional schematic isometric view of the oven shown in Figure 15 in an open configuration; Figure 18 is a schematic front view of an oven door shown in Figure 15; Figure 19 is a schematic cross-sectional view through line AA of the door shown in Figure 18; Figure 20 is a schematic bottom view of the door shown in Figure 18; Figure 21 is a schematic exploded view of the door shown in Figure 18; Figure 22 is a schematic top section view of the door shown in Figure 18; and Figures 23A to 23C are schematic top views of the airflow in an additional modality of a twin-fan (impeller) furnace. DETAILED DESCRIPTION OF THE INVENTION Figure 1 of the accompanying figures schematically represents an oven 1000 having an oven body 1002. The oven 1000 may be, for example, in the form of a countertop convection oven. The body 1002 has a user interface portion 1004. The front surface of the oven 1000 is defined primarily by the front surface of the vertically oriented user interface portion 1004 and a horizontally hinged door 1006 to the left of the user interface portion 1005. The outer surface of the door 1006 includes a well-defined padded frame or edge 1008 and a glass viewing window or panel 1010. It will be appreciated that, in a preferred embodiment, when the door 1006 is viewed from the front (i.e., facing the outer surface of the door 1006), the frame 1008 conceals the outer edge 1012 of the display panel 1010. The door 1006 includes a handle 1014 on an upper portion thereof. In the embodiment shown, the handle 1014 is horizontally oriented and supported at each end by a handle mounting bracket 1016. Consequently, it will be appreciated that a front surface 1005 of the door 1006 can be free of any visible fasteners. The door 1006 in the embodiment shown has one generally rounded corner 1018 and one generally square corner 1020. It is understood that in other embodiments (not shown), the door 1006 may include both rounded and square corners 1018, 1020 at any of the four corners of the door 1006. With reference to Figure 2, a rear surface 1022 of the door 1006 is provided primarily by the back of the display panel 1010. The door 1006 includes two magnetic projections 1024 and a bottom support 1026. In the embodiment shown, the rear surface 1022 of the door 1006 is primarily glass, and a peripheral margin or edge may be formed from several metal portions 1028, with no visible fasteners on the rear surface 1022 of the door 1006. Further details of the structure of the door 1006 are described in detail in the applicant's earlier International Application No. PCT / AU2016 / 051101, filed on November 16, 2016. For the sake of brevity, the full content of that International Application is incorporated herein by cross-reference. With reference to Figure 3, an interior or cooking cavity 1030 of the oven 1000 is shown. In the embodiment shown, the oven 1000 includes an assembly of an upper heating element 1032 and an assembly of a lower heating element 1033, each of which extends transversely between a first inner side wall (left side) (not shown) and a second inner side wall 1034 (right side) surrounding the cooking cavity 1030. In the embodiment shown, four upper heating elements 1036 and two lower heating elements 1037 are shown. The second inner side wall (right side) 1034 includes a centrally located inlet duct 1040, which has a grate portion 1042 and is surrounded by a conical or funnel-like inlet manifold 1044 on its cavity-facing side. In the embodiment shown, the features of the second inner side wall (right side) 1034, including the inlet manifold 1044 and the transversely extending notches 1046 forming guide rails for the furnace racks, are pressed into a sheet of metal. The second inner side wall (right side) 1034 also includes two arc-shaped discharge vents 1048, 1049 located in a matrix preferably formed around a common or nearly common diameter relative to the center of an impeller (described in further detail below).As will be discussed in further detail below, air is forced through the discharge vents 1048, 1049 in a manner that promotes a generally helical airflow pattern 1050. This airflow pattern 1050 is intended to expel air from the second inner side wall 1034 (right side), towards and around the thermal element assemblies 1032 and 1033. Subsequently, the airflow is drawn into an axial flow core 1052. The flow core 1052 moves towards the inlet manifold 1044 and is drawn past the grille portion 1042. The aforementioned and related airflow patterns are produced according to an illustrative convection impeller assembly 1060 as shown in Figure 4. The impeller assembly 1060 includes a radial impeller 1062 that can rotate within a closure assembly 1064. The closure assembly 1064 can have a flat front surface 1066 that includes an inlet opening 1068 and a vent array comprising two sub-arrays, which are two outlet openings 1070, 1071 that align with the discharge vents 1049, 1048 in the second inner side wall 1034 (right side) described above. The acquisition and exit openings are described as single openings, but it will be understood that a vent or opening may be subdivided into smaller vents or openings (e.g., openings 1072, 1073). The acquisition opening 1608 aligns with and cooperates with the grid portion 1042. In the embodiment shown, a rear surface 1074 of the closing assembly 1064 supports internal airflow guide fins 1076, 1077 that direct air to outlet openings 1070, 1071. The rear surface 1074 may be formed as a dome-shaped structure. A central opening 1078 in the rear surface 1074 accommodates one end of an output shaft 1080 of an electric motor 1082. The other end of the output shaft 1080 drives a motor cooling impeller 1084. The convection impeller assembly 1060, as depicted in Figure 4, is also shown in the cross-sectional schematic view of Figure 5. In Figure 5, the front surface 1066 of the closing assembly 1064 is shown installed behind the grille portion 1042. The outlet openings 1070, 1071 align with the discharge vents 1049, 1048 in the second inner side wall (right side) 1034. The airflow is established by the impeller 1062 and directed by stationary vanes 1085, 1086 into the cooking cavity 1030 by means of the outlet openings 1070, 1071. With reference to Figure 6, the rear surface 1074 of the locking assembly 1064 has a circular rim 1090 and a dome-like shape 1092. This arrangement can at least provide a convenient surface for openings through which the joining tabs 1094 can be joined. In the configuration shown in Figure 7, the outlet openings 1070, 1071 may be supplemented by the additional outlet openings 1096, 1097. The four outlet openings 1070, 1071, 1096, 1097 are aligned with the discharge vents 1048, 1049, and the additional discharge vents 1098, 10988. With respect to the orientation of the impeller 1062 depicted in Figure 7, the impeller 1062 can be seen to rotate counterclockwise, providing a counterclockwise airflow through the various openings 1070, 1071, 1096, 1097. The stationary fins 1085, 1086 described above may be provided in this arrangement. Consequently, the lowest opening and vent 1071, 1048 terminate adjacent to the nearest and outermost of the lower thermal elements 1037. The lower thermal elements 1037 and the lower vent and outlet openings 1071, 1097, 1048, 1099 are optional on some furnaces.In the configuration shown, an element 1100 supplies the lower front element. The uppermost opening and vent 1070, 1049 terminate adjacent to the nearest of the upper thermal elements 1036, the upper elements being the rearmost. In this way, the air discharged from the vents is directed by the helical flow pattern of the discharge toward and past the thermal elements. Each of the primary or proximal opening and vent pairs 1071, 1048 and 1070, 1049 can be supplied with secondary opening and vent pairs, which are 1096, 1098 and 1097, 1099. In some embodiments, fins 1085, 1086 are not required when secondary openings and vents 1096, 1098 and 1097, 1099 are present. In these examples, the aforementioned openings and vents are approximately equal in size and are located around a common diameter with reference to a centerline or axis of the rotating impeller 1062. The absence of vent openings or outlet openings and vents may define two dead zones on each of the front surface 1066 and the inner wall 1034. The dead zones are identifiable by an absence of significant perforations or ventilation in areas 1102, 1104 of the front surface 1066 and areas 1106, 1108 of the inner wall 1034. In the embodiment shown in Figure 8, the relationship between the impeller, vents, and heating elements in a convection oven is illustrated. In this example, the view is of the baking cavity 1030 of oven 1000, which faces a left-side inner wall 1110. The oven door opening 1006 would be on the left side 1112. In the embodiment shown, oven 1000 includes four upper heating elements 1036 and two lower heating elements 1037. It will be appreciated that in other embodiments (not shown), oven 1000 can be supplied with any number of upper and lower heating elements 1036 and 1037. Impeller 1062 is visible in Figure 8, although it is understood to be located behind both wall 1110 and the front surface 1066 of the closing assembly 1064 (surface 1066 is optional and not shown). Discharge vents are understood to be present in this example, generally the same size and aligned with the openings 1096 in the front surface 1066 of the closing assembly 1064. In this example, impeller 1062 rotates counterclockwise along direction 1114 when viewed from behind impeller 1062, or clockwise when viewed from the firing cavity 1030. The interior wall 1110 in the area at the front 1066 can be considered as a circle 1116 that is subdivided into four quadrants. The quadrants are defined by a vertical axis. 1118 passing through the rotating center of the impeller 1062 and a horizontal axis 1120 also passing through the rotating center of the impeller 1062. The quadrants are understood to be horizontal and vertical subdivisions that define a clock face with the nominal twelve o'clock position at the maximum vertical height 1122 of the circle 1116. The six o'clock position is located at the minimum vertical height 1124 of the circle 1116. The three o'clock position 1126 and the nine o'clock position 1128 are located along the horizontal axis 1120 and pass through the center of the impeller 1062. As suggested in Figure 8, a primary discharge vent 1130 in the wall 1110 is located entirely within the first quadrant (between the twelve o'clock and three o'clock positions) when the impeller 1062 rotates clockwise as viewed from the furnace cavity. In the depicted embodiment, the discharge vent 1130 is generally centered between the twelve o'clock and three o'clock positions, and preferably extends from the one o'clock position to approximately the two thirty position. The primary discharge vent 1130 is located below the two rear upper heating elements 1036. The primary discharge vent 1130 is preferably arched and extends over a diameter smaller than the circle 1116 mentioned above. In this example, the primary discharge vent 1130 is provided with a secondary vent 1136. The secondary vent 1136 extends partially into the first quadrant and partially into the second quadrant (between the three o'clock and six o'clock positions). The secondary vent 1136 extends from approximately the two thirty position to the four o'clock position. The arrangement of vents 1130 and 1136 can at least ensure that the air expelled from vents 1130 and 1136 is generally directed upwards in a direction 1138 towards the upper heating elements 1036. The helical motion of the air discharged from vents 1130 and 1136 carries the flow through the upper heating elements 1036 to the front of the furnace 1000, where it is then generally directed downwards in a downward direction 1140 towards the lower heating elements 1037. The orientation of the optional primary and secondary vents 1130 and 1136 is repeated in a diametrically opposite pattern with respect to the primary and secondary lower vents 1146 and 1148. The primary lower vent 1146 is located entirely within and preferably centered in the third quadrant (between the six o'clock and nine o'clock positions). The secondary vent 1148 is located partially within the third quadrant and partially within the fourth quadrant (between the nine o'clock and twelve o'clock positions). It will be appreciated that in other embodiments (not shown), any number of primary and secondary vents may be provided, or alternatively, a single elongated vent may be provided in place of the separate primary and secondary vents 1130 and 1136. 1146, 1148. It will be appreciated that in the described modality there are no substantial vent openings in the area between an upper end 1150 of the upper primary vent 1130 and an upper end 1152 of the lower or left-side secondary vent 1148. This area defines an outlet zone 1154 and its diametrically opposite companion dead zone 1156 can at least maintain optimized characteristics of the airflow discharged through vents 1130, 1136, 1146, 1148 and finally into the various upper and lower thermal elements 1036 and 1037. It will be understood that relatively small openings can be provided in the dead zones 1154, 1156 without compromising the optimization of the aforementioned flows. The arrangement of primary and secondary vents mentioned above has been found to provide a generally helical flow that is optimized to supply vent discharge to and through the thermal elements where the air is heated before the air comes into contact with the food being cooked in the cooking cavity. Figures 9 and 10 of the accompanying figures schematically represent a convection system for an alternative embodiment of a 2000 oven, which generally operates in the same manner as the 1000 oven described above, with similar reference numbers used to indicate similar characteristics. However, in this embodiment, an inlet manifold 2002 of the 2000 oven is located in a rear inner wall 2004 of the 2000 oven. Air is received at the center of the rear wall 2004 and blown through the inlet manifold 2002, through the impeller 1062, and into the oven's cooking cavity 2005. The inlet manifold 2002 and the impeller 1062 are located on a central shaft 2008, which generally corresponds to the center of the rear wall 2004. In the embodiment shown, the inlet manifold 2002 includes a plurality of air guides or vanes 2006 that at least partially surround the impeller 1062, and a pair of vertical heating elements 2010 located on each side of the impeller 1062. The plurality of air guides or vanes 2006 are assembled to the rear wall 2004 and provide channels that generally extend transversely from the center axis 2008 into a left-side portion 2012 or a right-side portion 2014 of the cooking cavity 2005. The pair of vertical heating elements 2010 also each includes a series of air guide portions 2011 (see also Figures 13A and 13B) that align with and correspond to the channels of the air guides or vanes 2006.In the embodiment shown, six air guides or vanes 2006 extend from the central axis 2008 to the left side portion 2012, and similarly, six air guides or vanes 2006 extend from the central axis 2008 to the right side portion 2012. The air guides or vanes 2006 are spaced apart along a vertical height of the rear wall 2004. It will be appreciated that in other embodiments (not shown), any number of air guides or vanes 2006 may be provided. As best shown in Figure 11, the inlet manifold 2002, with the help of the air guides or vanes 2006, directs the air from the impeller 1062 along a generally transverse direction from the central axis 2008 towards the left and right side portions 2012 and 2014 of the furnace 2000. Accordingly, the air generally moves linearly along the opposite paths 2016 and 2018, through the vertical heating elements 2010, and towards the left and right side portions 2012 and 2014, respectively. The air then moves towards a front portion 2020 of the cooking cavity 2005, through the upper and lower thermal elements 2026 and 2028, and back towards the rear wall 2004 along opposite paths 2022 and 2024, again through the upper and lower thermal elements 2026 and 2028.This air movement creates two strong air circulation cells defined by the opposing paths 2022 and 2024, facilitated by the location and geometry of the inlet manifold 2002, along with the arrangement of the air guides or vanes 2006 and the impeller 1062. It will be appreciated that the number, positioning, and curvature of the air guides or vanes 2006 match the airflow generated by the impeller 1062. This ensures that the airflow is distributed evenly and that little resistance is encountered when capturing and redirecting the air through the inlet manifold 2002. The uniform increase in airflow thus allows for more stable temperatures within the cooking cavity 2005 and even enables cooking across multiple rack positions simultaneously.In addition, it will be appreciated that the increased or faster airflow can at least reduce the boundary layer of air around the food being cooked, resulting in faster heat transfer and quicker cooking times. In Figure 12, the oven 2000 is shown with a pressure plate or cover 2030 having a mesh or grate portion located in its center 2032. The cover 2030 is located in the firing cavity 2005 adjacent to the back wall 2004 and the air guides or vanes 2006, with the mesh or grate portion 2032 positioned to extend through the impeller 1062. Consequently, the cover 2030 can at least facilitate airflow along the air guides or vanes 2006 initially along paths 2016 and 2018, before directing it along paths 2022 and 2024. The left and right side portions 2012 and 2014 of the firing cavity 2005 also include grate guide portions 2034 that interact with and maintain cable trays or racks that are inserted into the cooking cavity 2005. Returning to Figures 9 and 10, the structure and positioning of the 2010 vertical thermal elements will now be described in greater detail. In these figures, a motor 2040 is shown driving the rotation of the impeller 1062, and is mounted behind the back wall 2004 by means of a mounting member, such as the bracket or mounting plate 2042. As described above, the pair of vertical heating elements 2010 are located on each side of the impeller 1062, and each includes air guide portions 2011 (see also Figures 13A and 13B) that align with and correspond to the air guide channels or vanes 2006. It is understood that the vertical heating elements 2010 are separated by a sufficient distance from the central axis 2008 (and thus from the motor 2040) to prevent overheating of the motor 2040 during operation of the furnace 2000.The vertical heating elements 2010 can each be separated by a distance of approximately 127 to 145 mm from the central axis 2008. It will be appreciated that this distance may allow the use of heating elements with higher wattages, which may at least allow faster cooking times without harming the performance of the motor 2040. Figure 13C also shows the various illustrative dimensions of the central shaft 2008 to the various heater elements. For example, a distance 2029a of approximately 290 mm can be provided between heater element portions 2010a and 2010d of the heating element pair 2010, and a distance 2029b of approximately 254 mm can be provided between heater element portions 2010b and 2010c of the heating element pair 2020. In addition, a distance 2029c of approximately 145 mm can be provided between the central shaft 2008 and heater element portion 2010d, and a distance 2029d of approximately 127 mm can be provided between the central shaft 2008 and heater element portion 2010c.In this way, portions of heater 2010a and 2010b form a first pairing of groups arranged adjacent to one of the side edges 2031a of the cover 2030, and portions of heater 2010c and 2010d form a second pairing of groups arranged adjacent to the other side edge 2031b of the cover 2030. When the heating elements 2010 are sufficiently energized, the thermal electromagnetic radiation emitted from each of the heating elements 2010 is reflected by the rear wall 2004 into the cavity 2005 to form a visible illumination or red glow emanating from behind the side edges 2031a and 2031b of the cover 2030. The red glow provides a visual indication to a user of the operating status of the furnace 2000 and, more particularly, the temperature of the cavity 2005. The red glow would be visible during the initial heating phase of the oven cooking cycle 2000.In a typical existing convection configuration, the heat source is frequently and almost always hidden. However, in the present arrangement, the visible red glow allows the user to see what would otherwise be hidden, which can provide valuable safety information. Furthermore, the visible red glow allows for general recognition of the operating status of the Oven 2000, even when located away from the Oven 2000's 1004 interface. As best shown in Figures 13A and 13B, each of the vertical thermal elements 2010 has a generally invented U-shaped structure defined by two separate, parallel, elongated portions or legs 2050 connected at their upper ends by a curved part 2052. The vertical thermal elements 2010 also each include at least one mounting portion 2054 located toward an upper part of the U-shaped structure adjacent to the curved part 2052. The at least one mounting portion 2054 may be in the form of a bracket having an opening through it for the insertion of a fastener (e.g., a screw or a rivet). The location of at least one mounting portion 2054 allows the thermal element 2010 to be mounted vertically towards an upper surface of the inlet manifold 2002 or the rear wall 2004, which may at least prevent fluid or grease from escaping from the cooking cavity 2005.It will be appreciated that the U-shaped structure can also facilitate the use of a longer length of thermal element to ensure that a correct watt density can be achieved. It will also be appreciated that the structure and arrangement of the 2010 thermal elements can also allow the 2006 air guides or vanes to be positioned between the 1062 impeller and the 2010 thermal elements, which can at least ensure that the airflow from the 1062 impeller is captured directly by the 2006 air guides or vanes. This contrasts with a typical coil thermal element which can interrupt the airflow as soon as it is expelled from an impeller. Furthermore, the shape (i.e., curvature) and positioning of the air guides or vanes 2006 can at least reduce turbulence in the airflow, resulting in smoother and more efficient furnace operation. As best shown in Figure 14A, the air guides or vanes 2006 that at least partially surround the impeller 1062 are provided by a series of vane units 2060, each vane unit 2060 comprising an upper vane 2062 and a lower vane 2064. The upper and lower vanes 2062 and 2064 are connected by a support portion 2066 to define a channel between them. In Figure 14A to 14B, three left-side blade units 2060 and three right-side blade units 2060 are provided to define the twelve air guides or blades 2006 that extend from the center axis 2008 into the left and right side portions 2012 and 2014 as described above. The support portion 2066 of each blade unit 2060 includes wall mounting portions or openings 2068 to facilitate mounting of the blade unit 2060 to the rear wall 2004 / inlet manifold 2002 of the furnace 1000. In the embodiment shown, the support portion 2066 extends vertically while the upper and lower blades 2062 and 2064 extend transversely from it. When the vane unit 2060 is mounted to the rear wall 2004 / inlet manifold 2002, the upper and lower vanes 2062 and 2064 extend into the firing cavity 2005 of the kiln 1000. The termination point of the vane unit 2060 may also include a curve or wavy geometry, which is understood to reduce the hissing sound created as the air travels past the heating elements 2010. In particular, it will be appreciated that the waviness introduced by the wavy curve helps to dispense and mix air of different temperatures. Impeller design It is understood that the design of the 1062 impeller incorporates a number of complex variables, for example: a) Internal diameter The size of the internal diameter of the impeller (i.e., the impeller eye) dictates the amount of air intake possible. b) External diameter The size of the impeller's outer diameter (i.e., the overall size of the impeller) dictates the length and number of the impeller blades. c) Number of drive blades Given proper spacing, more blades often equate to high amounts of airflow. d) Impeller blade curvature Unlike flat blades, which draw air in by creating low pressure when the air is pushed away from the impeller eye, curved blades can collect the air and allow for a higher capture rate. Fine balancing is required to ensure the blade angle is tangent to the impeller eye to maximize airflow. e) Weight The impeller's design, material, and thickness dictate its weight, which has a lasting effect on the motor's performance and lifespan. The material selection, thickness, and weight also contribute to the impeller's ability to flex and deform during use. This deformation can cause vibration at high speeds, leading to noise. While a heavier impeller is easier to balance, it places more stress on the motor and reduces the speed at which the motor can rotate, thus limiting the impeller's potential airflow. Figure 14B shows an exploded view of the impeller structure 1062 in an illustrative embodiment. The impeller 1062 in this example includes a plurality of blades 2070 joined by circular pads 2072 and various fastening means 2074, 2076. ινίΛ / Engine cooling system Traditional motors used in convection ovens are AC short-circuited commutated coil motors, known for their simplicity, robustness, and affordability. The motor used in the oven described here is a BLDC permanent magnet motor, popular in devices such as drones and electronic cooling fans. These motors are known for their compact size, ability to reverse direction, and variable speed. While such motors are common in the electrical applications mentioned above, they are not typically found in high-temperature environments like ovens because BLDC motors are sensitive to high temperatures. To help the motor maintain a stable operating temperature, an additional component is often used. The rotating section of the motor is called the rotor. This component also houses the permanent magnets and the motor shaft. It is common practice to design the back of the rotor with surface cavities such as holes. However, this method does not ensure sufficient air penetration into the motor housing for cooling. Occasionally, a rear-mounted cooling fan is also used to ensure air circulation within the motor housing. This method requires a motor shaft to allow an axial cooling fan to be mounted behind the rotor. While effective, this method requires more components and space within the furnace housing. The benefits of using a BLDC motor are twofold. Firstly, the smaller motor size allows for a smaller external oven unit. Secondly, variable fan speeds can accommodate different types of food. For example, delicate items like cakes benefit from slow air circulation, while other foods, such as potatoes, require hotter, faster-moving air to ensure quick crisping. As discussed earlier, since BLDC motors are unfamiliar with high-temperature furnace environments, many motor components require modification to ensure proper motor operation in such environments. These areas of modification may include, for example: i) Modification for high temperatures Due to an integrated controller PCB and a low lubricant temperature rating, BLDC motors typically cannot operate safely above 55°C. Therefore, the following modifications are planned to prevent motor failure: • PCB with off-board controller; • specification of the increased lubricant temperature rating; • radiant thermal protectors and insulation placed around the motor; • after machining the motor shaft to reduce heat conduction to the motor housing; and • configuration of a motor shaft, to allow a rear-mounted cooling fan. i) Modification for high torque and RPM: BLDC motors typically operate small impellers at high RPMs. Due to the construction and airflow requirements of a furnace, an impeller is needed to move large volumes of air. A motor operating at sub-5000 RPM with sufficient torque to power a large impeller is required. In one embodiment of the herein described, a series of impeller fins are drilled and formed outward from the rear surface of the rotor (motor bell) of the 2040 motor. This design allows the rotor to act as a back-cooling impeller while the 2040 motor is in operation. This arrangement integrates the benefits of both traditional methods without the added component or size. Unlike traditional back-cooling methods for BLDC motors, this arrangement also does not require costly manufacturing processes such as back-machining, or additional components such as a rear-mounted cooling impeller. The overall size of the motor assembly can also be kept to a minimum, allowing a BLDC motor to operate safely in a hot and compact environment. BLDC motor control It is understood that it is extremely difficult to guarantee the absence of cold spots in an oven cavity. In cases where air circulates at a slower speed, air temperatures, and therefore cooking performance, can be negatively affected. A BLDC motor can be used to create the opportunity to reverse the impeller's rotation direction for a selected percentage of time. This redirection of the air disrupts the continuous flow, creating a temporary secondary airflow. This variation can at least help to make the airflow and temperature more uniform and consistent throughout the oven's cooking cavity. Furthermore, a furnace can be configured to house two convection assemblies facing each other from opposite furnace walls (e.g., left and right side furnace walls). Both furnace walls can be fitted with complete convection assemblies that include heating elements, a BLDC motor, an impeller, a pressure plate, and air guides or vanes. In one embodiment of the present description, an impeller designed for reversing action includes a series of flat blades to ensure that the air outlet matches both directions of rotation. When operating, mirrored convection assemblies can each create two sets of moving air cells. The intersection of these two sets of cells is located in the center of the cooking cavity. To ensure this area is exposed to consistent air velocity and temperature, the motor of one conventional assembly oscillates its speed at the inverse speed of the motor in the other connecting assembly. The increased speed of one motor is adjusted by the decreased speed of the other, causing the cell sets to expand and contract, creating a dynamic cell intersection point. Figures 14A, 14B to 21 of the accompanying figures schematically represent an additional alternative embodiment of a 3000 oven, which generally operates in the same manner as the 1000 and 2000 ovens described above, with similar reference numbers used to indicate similar features. In this embodiment, the 3000 oven includes a body 3002 and a hinged door 3006, which in turn includes a user interface portion 3004, a glass viewing window or front panel 3010, and a handle 3014. As best shown in the open configuration of the door 3006 in Figure 16 and the exploded view of the door 3006 in Figure 21, the door 3006 also includes a rear glass panel 3022 facing an interior or cooking cavity 3030 of the 3000 oven. Figure 17 shows door 3006 in the open configuration with the rear glass panel 3022 concealed to reveal a pair of LED lights 3040 and a rear door frame 3042. With reference also to Figure 21, and as will be described in further detail below, the control electronics (not shown) for oven 3000 are housed in an electronic housing 3044, between the rear door frame 3042 and a front door frame 3043 (where the user interface portion 3004 is located). It is understood that while the control electronics for oven 3000 are located in or adjacent to door 3006, the power electronics (not shown) for oven 3000 are located at the rear of oven 3000. In the configuration shown, the LED lights 3040 are mounted in the rear door frame 3042 and positioned on either side of the front display window or panel 3010.In the closed door configuration, the LED lights 3040 can be operated to direct light into the cooking cavity 3030, thereby reducing or eliminating shadows in the cooking cavity 3030 during food preparation. This contrasts with prior art ovens that typically include lights on the side(s) of the cooking cavity itself, which can cause shadows. It will be appreciated that in other configurations (not shown), any number of LED lights 3040 can be provided in any position on the rear door frame 3042 or other door components 3006. As described above, the oven control electronics 3000 are intended to be housed in the electronic housing 3044 of the door 3006. It is understood that typical ovens (i.e., countertop or built-in ovens) do not include control electronics in the oven door. This is because an oven door traditionally includes glass to allow viewing of the food being cooked in the cooking cavity, and the door is subjected to high temperatures from the oven during operation. In typical ovens, the control electronics are placed in a separate location from the door to take advantage of cooler areas in the oven, and also, for example, to take advantage of areas in the oven that can be cooled more easily by cooling fans. As such, the oven control electronics are not typically included in the oven door itself.There are also additional difficulties due to the complexity of the cable routing that must be provided to power the control electronics, and such cables may be subject to deformation over time due to the constant opening and closing movements of the door. A safe operating temperature for electronic systems is generally considered to be approximately 60 degrees Celsius. Therefore, in appliances such as ovens, design parameters must be used to ensure that temperatures do not reach dangerous levels. There are two main cooling methods typically used: active cooling and passive cooling. Active cooling refers to components that move air across moving parts to create negative heat transfer. Traditionally, such components include fans, including centrifugal, axial, and cross-flow fans. Active cooling is often more effective than passive cooling, but it can be heavier, more expensive, and more prone to failure. Passive cooling defines a component or geometry that creates negative temperature transfer without any moving parts. Traditionally, passive cooling can be achieved through components such as heat pipes or heat sinks to transfer heat from one place to another. As illustrated in the 3000 oven configuration, natural convection is used to passively cool temperature-critical components (primarily the electronic control components within housing 3042). By utilizing natural convection at the 3006 door of the 3000 oven, for example, the need for cooling fans can be avoided. In the embodiment shown, the door 3006 includes an air channel extending through its center. A first opening 3046 (see Figures 20 and 21) located in the lower portion of the front door frame 3043 provides an inlet to the air channel, while a second opening (slot) 3048 located in an upper portion of the front door frame 3043 provides an outlet from the air channel. The air channel is thus understood to pass through the electronic housing 3044 between the front panel 3010 and the rear panel 3022. As shown in the figures, the second opening (slot) 3048 is, in a preferred embodiment, an opening or slot extending transversely through a front face of the front door frame 3043.The second opening (slot) 3048 is also intended to be concealed or at least partially hidden from view (when viewing door 3006 from the front, in the closed configuration) by means of handle 3014. It is understood that air rises as it heats up, and in the embodiment depicted, an upward airflow can pass through the air channel running through the center of door 3006 (i.e., between the first opening 3046 and the second opening 3048). This airflow can reduce the touch temperatures of door 3006 and prevent the electronic control components within housing 3042 from reaching critical temperatures. It will be noted that the second opening (slot) 3048 is located in the upper portion of the front door frame 3042 to allow heated air from the air duct to escape. Therefore, the second opening (slot) 3048 is strategically positioned to: (a) allow natural convection airflow to exit through the top of the door 3006; (b) prevent the entry of any potentially spilled liquid or debris by being located on the front face of the front door frame 3042 (and not on the top surface of the door 3006); and (c) be concealed by the handle 3014 of the door 3006, thus maintaining a pleasing aesthetic from the front view of the oven 3000. The above arrangement can therefore allow the 3000 oven to maintain safe temperature regulation through any cooking temperature or duration for which the 3000 oven can be operated. Furthermore, in the event of a power outage, or if the user abruptly disconnects the power cord, natural convection cooling can at least allow the 3000 oven's electronic control components to cool down with little or no damage (e.g., overheating and failure). Furthermore, if door 3006 is opened after a high-temperature cooking process and subsequently left open, it will be in a horizontal, rather than vertical, position. Consequently, the natural (vertical) convection path will no longer be available to cool the control electronics. In this scenario, latent heat within door 3006 can be released, causing a potentially dangerous temperature increase in the control electronics. Because this scenario is anticipated as a common use case for door 3006, its geometry, material, and components are designed to ensure sufficient thermal regulation to allow the oven 3000 to withstand this temperature increase.For example, in the mode shown, and as best illustrated in Figure 22, a distance 3050 of approximately 30 mm can be provided between the LED lights 3040 and the front panel 3010, and a distance 3052 of approximately 25 mm can be provided between the control electronics and the front panel 3010. Figures 23A to 23B show the airflows of a double-fan (impeller) furnace 4000, which operates in the same manner as the 1000, 2000, and 3000 furnaces described above, with similar reference numbers used to indicate similar characteristics. Two pairs of strong airflow cells are provided, defined by opposing paths 4022a, 4022b, 4024a, and 4024b, similar to cells 2022 and 2024 described above. By varying the fan speeds of each impeller fan 1062a and 1062b, a centerline between the two pairs of air cells can be adjusted. For example, in Figure 23A, each fan (impeller) 1062a, 1062b operates at a fan speed of 50%, so that the centerline between the two pairs of air cells is also provided at the center of the 4000 furnace.In Figure 23B, the left-side fan (impeller) 1062a operates at 70% fan speed, while the right-side fan (impeller) 1062b operates at 30% fan speed, so that the centerline is provided toward the right side of oven 4000. In Figure 23C, the left-side fan (impeller) 1062a operates at 30% fan speed, while the right-side fan (impeller) 1062b operates at 70% fan speed, so that the centerline is provided toward the right side of oven 4000. Typically, in the centerline between two pairs of air cells, there is slow-moving air. The twin-fan arrangement described above can at least allow the centerline to move, ensuring that food can be cooked evenly by reducing or completely eliminating cold spots. The various oven shapes and associated components described above can offer one or more of the following advantages. For example, the arrangement of air guides or vanes can ensure that the airflow within the oven's cooking cavity is distributed evenly, with minimal resistance encountered when capturing and redirecting air through the inlet manifold. This uniform increase in airflow can also lead to more stable temperatures within the oven's cooking cavity and even allow for simultaneous cooking across multiple rack positions. Furthermore, the increased or faster airflow can reduce the boundary layer of air surrounding the food being cooked, resulting in faster heat transfer and quicker cooking times. It will also be appreciated that the distance or separation between the vertical heating elements and the motor can at least prevent the motor from overheating during oven operation. Consequently, heating elements with higher wattages can also be used to allow for faster cooking times without compromising motor performance. Furthermore, the structure and arrangement of the heating elements can also allow air guides or vanes to be positioned between the impeller and the heating elements, which can at least ensure that the impeller's airflow is captured directly by the air guides or vanes, resulting in less turbulent airflow. The design of the BLDC motors described above can also eliminate the need for costly manufacturing processes, such as post-machining, or additional components such as rear-mounted cooling impellers. The overall size of the motor assembly can also be kept to a minimum, allowing the motor to operate safely in the typically hot and confined environment of the furnace. Furthermore, the positioning of the electronic control components in the door and the associated air channel design can at least utilize natural convection air currents to cool the electronic control components in the oven door, which can at least allow for safe regulation of the oven temperature. Although the invention has been described with reference to preferred embodiments, those skilled in the art will appreciate that the invention can be carried out in many other ways.

Claims

1. An oven having a body that includes a base, a roof, and side walls extending between the base and the roof, the side walls at least partially surrounding a cooking cavity, the oven including: an impeller assembly mounted to a first side wall of the oven body, the impeller assembly including: an impeller that is rotatable to direct airflow into the cooking cavity; a plurality of air guides at least partially surrounding the impeller, the air guides each defining a channel generally extending transversely from a central axis of the impeller; and a pair of heating elements located on each side of the impeller, whereby air directed from the impeller travels transversely along the channels of the air guides, through the heating elements, and into the cooking cavity.

2. The oven according to claim 1, characterized in that the air guides each include an upper vane and a lower vane, the upper and lower vanes being connected by a support portion to define the channel between them.

3. The oven according to claim 1 or claim 2, characterized in that the air guides are mounted to an inlet manifold of the impeller assembly.

4. The oven according to any one of the preceding claims, characterized in that the channel of each air guide extends transversely into either a right-hand side wall or a left-hand side wall of the oven, wherein the opposing channels create linearly opposite flow paths, and wherein the air moving along the opposing channels is subsequently moved into a front portion of the oven, and then into a rear wall of the oven.

5. The oven according to claim 4, characterized in that the air movement creates two air cells within the cooking cavity, the two air cells having opposite flow paths.

6. The oven according to any one of the preceding claims, characterized in that the air guides are located between the impeller and the thermal elements, wherein the thermal elements are separated from the central axis of the impeller and thus from a motor of the impeller assembly by a distance.

7. The oven according to any one of the preceding claims, characterized in that the heating elements each have a generally U-shaped structure defined by two separate, parallel, elongated portions connected at their upper ends by a curved portion. 5 8. The oven according to claim 7, characterized in that the thermal elements each include at least one mounting portion located towards an upper part of the U-shaped structure adjacent to the curved portion.

9. The oven according to any one of the preceding claims, characterized in that during use, the thermal electromagnetic radiation emitted from each of the thermal elements is reflected into the cavity to provide a visual indication of an operating state of the oven.

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