Patent Publication Number: US-2007114220-A1

Title: Electric oven

Description:
CROSS REFERENCE TO RELATED-APPLICATIONS  
      This application is a division of copending application Ser. No. 11/102,560 filed 5 Apr. 2005 with a claim to the priority of Italian application MI 2004A 000715 filed 9 Apr. 2004. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates to an electric oven in particular for cooking or heating food products. In particular, the invention relates to ovens equipped with one or more electrical resistance wires capable of irradiating energy in the form of infrared radiation.  
     BACKGROUND OF THE INVENTION  
      In such apparatuses one or more racks are provided, generally in the form of metal wire grids, for directly supporting the food or trays containing food to be cooked or roasted.  
      One of the drawbacks of conventional cooking apparatuses during cooking consists of the fact that to obtain a homogeneous distribution of heat and an equally homogeneous cooking or browning of the food it is necessary to remove the trays from the cooking chamber to mix the food or turn the trays, involving a waste of energy that is lost with the opening of the door of the apparatus, a lengthening of the cooking times and the need for the operator to be present attending to the food.  
      In some cooking devices, for example in many microwave ovens, the support plate for the food or for a tray containing the food is made to rotate by a mechanism that has a pulling piston that engages the plate centrally and at the bottom. Such a system could only be implemented in an oven of the type referred to above by eliminating the crumb tray arranged below the resistance wires that produce the heat and therefore would cause a substantial complication of the cleaning operations. Indeed, providing such a system in an oven of the type described above would prevent forward ejection from the crumb tray.  
      Another drawback of conventional ovens consists of the fact that it allows only a single rack arranged at a predetermined height in the cooking chamber to be removed.  
      Yet another drawback of conventional ovens is that the ejection system of such a rack can have a substantial metal mass that introduces a thermal inertia that hinders the correct roasting or browning of food.  
     OBJECTS OF THE INVENTION  
      An object of the present invention is, therefore, making an electric oven in particular for cooking or heating food that allows the aforementioned technical drawbacks of the prior art to be eliminated.  
      In this technical task an object of the invention is making an electric oven in particular for cooking or heating food that allows optimal cooking without lengthening cooking times and/or without wasting energy and/or without requiring the operator to be present watching over the food.  
      Another object of the invention is making an electric oven in particular for cooking or heating food that allows many racks to be removed simultaneously from the cooking chamber without the cleaning operations being penalized and/or without complicating the forward ejection of the crumb tray.  
      The last but not least object of the present invention is making an electric oven in particular for cooking or heating food that allows the maximum possible flexibility of use by allowing the racks to be interchanged while keeping the functionality of the apparatus unchanged.  
      The last but not least object of the invention is making an electric oven in particular for cooking or heating food that allows a correct roasting and/or browning of food.  
     SUMMARY OF THE INVENTION  
      These and others objects, according to the present invention, are attained by making an electric oven in particular for cooking or heating food, comprising a cooking chamber housing one or more removable racks suitable for supporting said food and slidably engaged with corresponding side guides of said cooking chamber, with at least one rotatable rack supported by one of said removable racks, and with rotation actuation means for the rotatable rack positioned peripherally and tangentially to it.  
      The present invention also is an electric oven in particular for cooking or heating food, comprising a cooking chamber having one or more removable racks engaged with corresponding guides, and a closing door hinged at the open front side of the cooking chamber, with simultaneous ejection means of the one or more removable racks. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING  
      Further characteristics and advantages of the invention shall become clearer from the description of a preferred but not exclusive embodiment of the oven according to the invention, illustrated for indicating and not limiting purpose in the attached drawings, in which:  
       FIG. 1  is a perspective view from the front of a preferred way of making the cooking apparatus of the present invention, in which for the sake of clarity the racks have been removed from the cooking chamber;  
       FIG. 2  is a perspective view from the front of the cooking chamber of the device of  FIG. 1 , in which two removable racks are illustrated (with the door of the cooking chamber in closed position) one of which carries the rotatable rack;  
       FIG. 3  is a perspective view from the front of the cooking chamber of the device of  FIG. 1 , in which two identical removable racks are illustrated (with the door of the cooking chamber closed) that can be used should it not be necessary to rotate the food to be cooked inside the cooking chamber;  
       FIG. 4  is a perspective view from an outer side of the cooking chamber of the device of  FIG. 1 , in which the ejection system is in the configuration with the door of the cooking chamber closed;  
       FIG. 5  is a different perspective view from an inner side of the cooking chamber of the device of  FIG. 1 , in which the ejection system is in the configuration with the door of the cooking chamber being open; and  
       FIG. 6  is a perspective view from an outer side of the cooking chamber of the device of  FIG. 1 , in which the ejection system is in the configuration with the door of the cooking chamber open. 
    
    
     SPECIFIC DESCRIPTION  
      With reference to the quoted figures, an electric oven in particular for cooking or heating food products is shown wholly indicated with reference numeral  1 . The oven  1  has an outer housing  2  in which a cooking chamber  3  is housed having a front side  4  closed by a door  5  hinged preferably about a horizontal axis arranged substantially at the base of the same front side  4  of the cooking chamber  3 . The bottom  6  of the cooking chamber  3  slidably supports a crumb tray  7  that can be removed from the front side  4  of the oven  1  through a slit situated between the bottom  6  itself of the cooking chamber  3  and the door  5 . Preferably, the crumb tray  7  in withdrawn position in the cooking chamber  3  extends outside the cooking chamber  3  with a handle  9  for moving it.  
      In the space between the outer housing  2  and a lateral side of the cooking chamber  3  there are the controls (not illustrated), the operating parameters of which (for example cooking time and temperature) can be controlled by the operator through suitable adjustment knobs  10  on the front side  4  of the oven  1  to one side of the door  5 .  
      Inside the cooking chamber  3 , immediately above the crumb tray  7 , a first electrical resistance  11  is positioned horizontally suitable for cooking the food. Preferably, at least one second electrical resistance (not shown) is also positioned horizontally immediately below the top side of the cooking chamber  3 .  
      The cooking chamber  3  has pairs of opposite lateral guides  12  in which corresponding removable racks  13  slidably engage, in particular pairs of opposite guides  12  formed as horizontal grooves  14  of the side walls of the cooking chamber  3  and suitable for receiving the side edges of the removable racks  13 . Each removable rack  13  consists of one or more metal wire elements  15 , rectilinear and/or shaped and/or intertwined and connected to form a grid, since the structure must not hinder a correct and homogeneous distribution of the heat and at the same time must ensure that crumbs or whatever else coming from the cooking and/or roasting of the food can be collected by the tray  7 . The removable racks  13  are intended to support the food directly or through a cooking container. At least one removable rack  13 , in particular the bottom one, can also be intended to support a rotatable rack  16  that can be made to rotate by suitable actuation means  17  positioned tangentially and peripherally to it ( FIG. 1 ).  
      The rotatable rack  16 , supported by the removable rack  13 , is in turn intended to directly or indirectly support the food to be cooked, and it can be made to rotate by actuation means  17  ( FIG. 1  only) about a vertical axis substantially passing through its center. In the preferred embodiment illustrated here the rotatable rack  16  has a circular outer edge and a section suitable for supporting, coaxially or fixedly, accessories such as a circular grill  18  (or a pan), of substantially the same diameter. The removable rack  13  intended to support the rotatable rack  16  has at least one first circular metal wire element  37  for supporting the rotatable rack  16 , and the first circular wire element  37  is supported from diametrally opposite sides by second and third shaped wire elements  19  in turn slidably engaged in grooves  14  of the side walls of the cooking chamber.  
      The actuation means  17  preferably has a magnetic motion transmission between a pinion  22  and the rotatable rack  16 , which in such a case is metallic. The pinion  22  is therefore made from magnetic material, for example a permanent magnet, and is arranged with its rotation axis horizontal so that its side surface is in contact with the bottom surface of the rotatable rack  16 . The pinion  22  is actuated by the shaft of a motor  23  positioned preferably in the space between a side wall of the housing  2  and the adjacent lateral side of the cooking chamber  3 , and exerts an attraction on the contact surface with the rotatable rack  16  avoiding sliding thereof. In a different configuration the motor  23  could also be behind the cooking chamber. The magnetic transmission of rotary motion between the pinion  22  and the rotatable rack  16 , as well as ensuring perfect effectiveness even when one of the two parts is greasy, is particularly quiet, does not have problems of interlocking and can easily be inspected and cleaned. The magnetic pinion  22  can be made with a cylindrical permanent magnet having opposite poles at its ends, or else with a plurality of magnetic disks and non-magnetic metal disks stacked alternately with two non-magnetic metal disks at the ends. In the second case it is possible to obtain an increase in magnetic flow density through the lateral surface of the pinion  22  and at the same time to limit the force of the magnetic field directed axially.  
      The transmission of motion between the pinion  22  and the rotatable rack  16  can also be of the mechanical type, in a first case via a high-friction coating of the pinion  22 , for example made from rubber, in a second case by providing the pinion  22  with teeth that mesh with a rack extending circumferentially on the rotatable rack  16 .  
      Of course, the rotation of the rotatable rack  16  can be enabled or disabled by the operator through a suitable button that commands the opening/closing of a switch of an electric power supply circuit of the motor  23 .  
      According to another aspect of the invention, the oven  1  has ejection means of the removable racks  13 , preferably able to be actuated by the opening/closing of the door  5 . Such ejection means comprise a linkage  25  housed in the space between a side wall  27  of the cooking chamber  3  and the housing  2  of the oven  1 , preferably in the same space where the motor  23  is found. The linkage  25 , which is oriented in a vertical plane, comprises an equalizer lever  26  pivoted at  50  on the side wall  27  and/or to the housing  2  and having a first arm  28  on which is pivoted one end of a connection link  29  also pivoted on the door  5  and a second command arm  30  of a thruster element  31  of the removable racks  13 . The link  29  is pivoted on the end of the equalizer lever  26  and on the door  5 , in particular at a vertical edge thereof.  
      The thruster element  31  has a first part  32  outside the cooking chamber  3  and slidably engaged in an L-shaped slot  33  of the second arm  30  of the equalizer lever  26 , and a second part  34  inside the cooking chamber  3  and slidably engaged in an opening  35  in particular behind the removable racks  13 . The first part  32  of the thruster element  31  is fixed to a substantially vertical rotation axis  38  and has at least one horizontally extending first element  39  engaged with the slot  33 . The second part  34  of the thruster element  31  has a second vertically extending element  40  engaged in the opening  35  of the racks  13 .  
      The slot  33  is preferably angular in shape so that the first element  39  is engaged with one of the legs of the slot  33  when the door  5  is open and with the other leg when the door  5  is closed.  
      The operation of the oven according to the invention is clear from what has been described and illustrated and, in particular, is substantially the following:  
      Let us suppose that two different foods must be cooked in the oven, one of which, arranged on the rotatable rack  16 , needs to be rotated in order to be cooked more homogeneously. After having set the cooking time and temperature and having enabled the rotation of the rack  16 , the operator closes the door  5  and switches on the oven.  
      After the oven has been switched on, the motor  23  periodically or continuously rotates the pinion  22 , which transmits its rotation to the rack  16 , for rotation of the food supported by it.  
      At the end of cooking of one or both of the foods, the operator opens the door  5 .  
      During opening of the door  5 , the link  29  makes the equalizer lever  26  rotate, the slot  33  of the equalizer lever  26  in turn makes the thruster element  31  rotate, since it is engaged with the first element  39  of the thruster element  31 , and the second element  40  of the thruster element  31  goes from a first withdrawn operating position substantially close to the rear of the cooking chamber  3  to a second advanced operating position toward the front of the cooking chamber  3 .  
      Since the element  40  is fixed to the opening  35  of the removable racks  13 , as it advances it also drags them forward to the point of partially ejecting them from the cooking chamber  3 .  
      The element  40  comes out from the opening  35  during advancing to definitively free the rack  13 .  
      The unhooking of the element  40  from the racks  13 , for example for cleaning or inspection, takes place by pulling the racks  13 , which at the end of the opening stroke of the element  40  are disengaged from it.  
      In the reverse operation, by closing the oven door, the element  40  in its curved return trajectory once again engages in the opening  35  of the removable racks  13  pulling them inside the cooking chamber.  
      The oven thus conceived can undergo numerous modifications and variations, all of which are covered by the inventive concept; moreover, all of the details can be replaced with technically equivalent elements. In practice, the materials used, as well as the sizes, can be whatever according to the requirements and the state of the art.