Abstract:
A rotisserie oven with a self-cleaning mechanism in the form of a lifting wash arm. The wash arm is driven to lift and rotate when washing the oven by the action of the pressure from the wash water used therein. By lifting, the wash arm negates the sealing action of fatty build-up around its base which would otherwise impede its rotation.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of U.S. application Ser. No. 61/021,102, filed Jan. 15, 2008, and herein incorporated by reference. 
     TECHNICAL FIELD 
     This application relates generally to ovens used for cooking food product and, more specifically, to a rotisserie oven with an integrated cleaning system including a lifting wash arm. 
     BACKGROUND 
     Various types of ovens are used for cooking food product. Rotisserie ovens are commonly used in the retail environment to cook chickens and other food products in a manner that permits store customers to view the food product during cooking. Rotisserie style cooking tends to result in grease, juices and food particles within the oven that require the oven to be cleaned regularly. It would be desirable to provide a rotisserie oven (or other type of oven) with a self-cleaning system including advantageous features. 
     SUMMARY 
     In some aspects, a self-cleaning rotisserie oven includes a rotatable spray arm mounted to enable the spray arm to lift as a result of forces generated by water pressure during flow through the arm. 
     In an aspect, a rotisserie oven includes a cooking compartment and a convection system including a heating element and ventilation system configured to heat the cooking compartment. A rotor is positioned within the cooking compartment. A spray arm assembly is within the cooking compartment and includes a spray arm configured to spray liquid into the cooking compartment. The spray arm is mounted for rotation about an axis and configured to be in a lowered position when not spraying liquid and configured to move axially upward along the axis into a raised position when spraying liquid. 
     In another aspect, a self-cleaning oven includes a cooking compartment and a heating system configured to heat the cooking compartment. A spray arm assembly is within the cooking compartment and includes a spray arm configured to spray liquid into the cooking compartment. The spray arm is mounted for rotation about an axis and configured to be in a lowered position when not spraying liquid and configured to move axially upward along the axis into a raised position when spraying liquid. 
     In another aspect, a spray arm assembly for use in a self-cleaning oven includes a spray arm configured to spray liquid into a cooking compartment of the self-cleaning oven. The spray arm is mounted for rotation about an axis and configured to be in a lowered position when not spraying liquid and configured to move axially upward along the axis into a raised position when spraying liquid. A bearing journal defines an upper seat and a lower seat. A bearing is mounted for rotational and axial movement with respect to the bearing journal such that in the lowered position a bottom portion of the bearing engages the lower seat and a top portion of the bearing is spaced from the upper seat, and such that in the raised position the top portion of the bearing engages the upper seat and the bottom portion of the bearing is spaced from the lower seat. 
     In another aspect, a method of cleaning a rotisserie oven including a rotor located within a cooking compartment and a convection system including a heating element and ventilation system configured to heat the cooking compartment is provided. The method includes rotating a spray arm of a spray arm assembly within the cooking compartment about an axis during a cleaning operation. The spray arm moves axially upward along the axis into a raised position when spraying liquid. The spray arm moves axially downward along the axis to a lowered position when not spraying liquid. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a front perspective of a rotisserie system; 
         FIG. 2  is a front perspective of another embodiment of a rotisserie system; 
         FIG. 3  is a schematic side view of one embodiment of a cooking chamber; 
         FIG. 4  shows a floor of a cooking chamber including a spray arm assembly and drain manifolds; and 
         FIGS. 5 and 6  show one embodiment of a lifting spray arm assembly. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a rotisserie system  10  is shown including a rotisserie oven  12 A stacked atop another rotisserie oven  12 B. Each oven includes a respective control interface  14 A,  14 B, which may include a variety of components, such as an information display area, a numeric keypad, ON/OFF buttons/keys, function specific buttons/keys, and/or various indicator lights. Each oven includes a vertically hinged access door  16 A,  16 B with a respective handle  18 A,  18 B and glass front  20 A,  20 B for viewing the rotisserie operation. The rear side of the oven may also include a viewing window, and in some cases may be formed by a rear door. A rotor  22 A,  22 B within each oven is also shown. The rotor  22 A and  22 B rotates a spit  23  that carries food products, such as chickens during cooking (see  FIG. 2 ). The illustrated system is supported by wheels  24  for ease in repositioning the system, with one or more of the wheels  24  including a lock feature. Referring to  FIG. 2 , a rotisserie system  30  is shown with a single oven  32  stacked atop a lower cabinet  34 . The rotor  42  within oven  32  includes birds  34  loaded thereon as per a typical rotisserie cooking operation. 
       FIG. 3  is a side view layout showing an exemplary oven chamber  40 . During rotisserie cooking operations, the rotor  42  rotates as heat is generated by a heating system  44 . In the illustrated embodiment, the heating system  44  is formed by heating elements  46  located above an upper plate or shield  48 . The plate  48  includes one or more intake openings  50  with associated convection fans  52  arranged to draw air into the openings  50  from the chamber  40 . The fans  52  push the air forward and rearward and across the heating elements  46  to pick up heat. The heated air is then directed back into the chamber  40  at forward and rearward slots  54  and  56 . Baffles  55  and  57  guide the air inward toward the rotor  42  at the center of the chamber  40  as the heated air passes through the ventilation slots  54  and  56 . The space above the plate  48  may include other directional plates or baffles to more effectively produce the forward and rearward air flow. 
     The rotisserie oven includes a self-cleaning feature that enables the oven to be cleaned during a self-cleaning mode of operation. For this purpose the oven may generally have hook-ups to a source of water and cleaning agent, and may also include a drain path and hook-up to enable the cleaning water to be purged during various points of the cleaning operation. The cleaning operation may include one or more stages, including pre-wash, wash and/or rinse stages. Different cleaning modes (e.g., which may provide different levels of cleaning) may be provided for user selection based upon the user&#39;s observation of how clean or dirty the oven is prior to cleaning. 
     In one implementation the self-cleaning feature includes the use of a spray arm assembly  60 , shown in  FIG. 3  at a bottom portion of the cooking chamber  40 . As shown in  FIG. 4 , the spray arm assembly  60  includes a rotatable spray arm hub  66  upon which is mounted one or more spray arms  61 . Each spray arm  61  includes a multiplicity of nozzle openings  62  for ejecting sprays of water during cleaning, and the force of the ejected water urges each arm  61  to rotate. Water is evacuated from the bottom of the chamber  40  through use of the drain strainers  67 , which lead to a lower sump area where cleaning liquid collects for recirculation via a pump. Other stationary and/or rotating wash arms and/or nozzles could also be located elsewhere within the oven chamber  40  and/or above the plate  48 . 
     Referring to  FIGS. 5 and 6 , an advantageous spray arm assembly  60  is shown. In particular, liquids dripping from product being cooked can tend to bond the spray arm hub  66  to its stationary seat  68  at the circumferential periphery  90 , preventing or limiting arm rotation. As shown in  FIGS. 5 and 6 , the bearing journal  70  is formed longer than the bearing  72  to allow for vertical travel of the bearing  72  and spray arm hub  66  along the journal  70 . As a result, when the spray arm hub  66  is at rest with no flow/water pressure, a gap  74  is formed between the rim of the journal  70  and the top edge of the bearing  72 . When water is applied during a cleaning operation, water flows through a channel  71  within the journal  70 , and upon exiting the journal  70  the water exerts pressure on the underside  76  internal of the hub  66 . The flow is diverted by the underside  76  of the hub  66  to flow through the channel  63  of each spray arm  61 , and exits each arm  61  through the nozzles  62  therein (shown in  FIG. 4 ). The water pressure on the underside  76  internal of the hub  66  lifts the hub  66  sufficiently far to break the bond at the periphery  90  between the hub  66  and the stationary seat  68 , allowing the hub  66  and arms  61  to rotate freely for effective cleaning. Thus, during cleaning, a gap  75  exists between the lower edge of the spray arm hub  66  and its stationary seat  68 . The lower part of the journal  70  is threaded for securing it to a corresponding threaded opening at the bottom of the chamber  40 , and so remains stationary during movement of the bearing  72  and hub  66 . Other structural arrangements could be used to produce spray arm lift. By lengthening the journal  70  relative to the bearing  72 , the bonding problem is solved while adding no additional parts and minimal additional cost to the spray assembly manufacturing process. 
     In one implementation the size of the gap  74  is between about 0.040″ and 0.125″, but larger or smaller gaps could be used. A gap of at least about 0.020″, and more particularly at least about 0.040″, or even more particularly at least about 0.060″ may be beneficial. 
     The above-described spray arm assembly  60  may have one or more of the following advantages. The spray arm assembly can distribute liquid throughout the cooking chamber and can reduce stripe pattern formation in the cooking chamber due to rotation of the spray arms while spraying liquid. As water pressure builds in the spray arm assembly, the pressure is used to lift the spray arms from the stationary seat. This lifting action can be used to break up grease, dirt and debris to ease start up rotation of the rotating spray arms. The rotisserie oven can be stacked as shown in  FIG. 1 , located on a stand as shown by  FIG. 2 , located atop a counter, located atop a combination oven, located atop a convention oven, etc. In some embodiments, the rotor  42  may rotate baskets that hold the food product instead of spits. 
     It is to be clearly understood that the above description is intended by way of illustration and example only, is not intended to be taken by way of limitation, and that other changes and modifications are possible.