Patent Publication Number: US-2010126357-A1

Title: Removable grill for cooking apparatus

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority from U.S. provisional patent application No. 60/731,473, filed Oct. 31, 2005, which is pending. 
    
    
     TECHNICAL FIELD 
     The invention relates to cooking appliances and more particularly to cooking and baking grills having removable grill surfaces. 
     BACKGROUND 
     Appliances for cooking food which use upper and lower opposed cooking surfaces are widely used for both home and commercial applications. For home applications, sandwich, hamburger and waffle grills are popular. Typically these will consist of a pair of heated grills or griddle plates, each having a fixed lower heated griddle plate and a pivoting heated upper griddle plate which can be manually pivoted by an attached handle into, or out of, position above the fixed griddle plate. In commercial applications, waffle cones for ice cream shops are often baked on-site using manual waffle cone griddles also called pizelle irons. Many restaurants provide pannini grills for baking pannini sandwiches in which a top cooking element is lowered onto the sandwich to cook both sides of the sandwich simultaneously. The present inventor has designed waffle cone and pannini grills in which the upper grill surface is automatically raised and lowered, as shown in U.S. Pat. Nos. 6,044,755 and 6,321,639. 
     The grills on such appliances require constant cleaning to remove grease and waste food material Also it may be desirable to change the grill surface to cook different food types. consequently various mechanisms have bee developed to permit removal and replacement of the grill surfaces. For example, U.S. Pat. Nos. 4,799,619 and 5,070,775 disclose two-sided cooking devices in which the cooking surface of the upper movable platen is removably secured by threaded nuts and bolts. U.S. Pat. Nos. 4,002,112; 6,429,409 and 6,820,537 disclose cooking appliances with removable grill plates wherein the grill plate is removably held in place by a latch or spring clip. Particularly for commercial applications such designs may not be sufficiently durable to tightly secure the grill after repeated replacements and repetitive uses. Also where the latch is exposed it may become caked with food and grease. It is desirable therefore to provide a design for a removable grill which is both convenient to replace and durable 
     SUMMARY OF INVENTION 
     The invention provides a removable grill for the cooking plate assembly of an appliance for baking or grilling food items wherein the cooking plate assembly comprises a heater assembly, the removable grill having a cooking side comprising a cooking surface and a connecting side opposite to the cooking side with a raised boss extending from the connecting side, the heater assembly comprising a central aperture for receiving the raised boss of the removable grill and the removable grill comprising a spring element secured to the raised boss on the connecting side and adapted to removably engage the heater assembly when the boss is inserted into the central aperture of the heater assembly and the grill is rotated relative to the heater assembly from a first position in which the grill can be removed from the heater assembly to a second position wherein the heater assembly is secured to the grill and is positioned between the grill plate and the spring element. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
       In drawings which disclose a preferred embodiment of the invention: 
         FIG. 1  is a perspective view of a cooking appliance; 
         FIG. 2  is a side view thereof; 
         FIG. 3  is a cross-section through the grill, in perspective; 
         FIG. 4  is a cross-section through the grill, in perspective from above; 
         FIG. 5  is a top perspective view of the grill/heater module assembly in unlocked position; 
         FIG. 6  is a top view of the grill in locked position; 
         FIG. 7  is an exploded perspective view of the grill/heater module assembly from above; 
         FIG. 8  is an exploded perspective view of the grill/heater module assembly from below; 
         FIG. 9  is a top perspective view of the heater assembly; 
         FIG. 10  is a cross-section of the heater assembly shown in  FIG. 9 ; 
         FIG. 11  is a top perspective view of the grill plate; 
         FIG. 12  is a top perspective view of the grill plate with leaf spring attached; 
         FIG. 13  is a top perspective view of the grill plate with heat transfer plate in position for attachment; 
         FIG. 14  is a top view of the grill in unlocked position; and 
         FIG. 15  is a top view of the grill in locked position. 
     
    
    
     DESCRIPTION 
     Throughout the following description, specific details are set forth in order to provide a more thorough understanding of the invention. However, the invention may be practiced without these particulars. In other instances, well known elements have not been shown or described in detail to avoid unnecessarily obscuring the invention. Accordingly, the specification and drawings are to be regarded in an illustrative, rather than a restrictive, sense. 
     With reference to  FIG. 1 , a cooking appliance  10  for baking or grilling food items such as waffle cones or pannini sandwiches is shown, of the type disclosed on the present inventor&#39;s U.S. Pat. Nos. 6,044,755 and 6,321,639, which are incorporated herein by reference. It has two cooking plate assembly pairs  12 , 14  each having opposed cooking plate assemblies  16 ,  18 , and  20 ,  22  respectively. Upper cooking plate assemblies  16 ,  22  pivot on arms  24 ,  26  into and out of position with respect to the lower cooking plate assemblies  18 ,  20 . In the particular embodiment shown, arms  24 ,  26  are automatically pivoted on rotating shafts  30 ,  32  driven through linkages in linkage housings  34 ,  36  which are in turn driven by two electric motors in main housing  38 . 
     The construction of the cooking plate assemblies is shown in further detail in  FIGS. 3-14 . Each cooking plate assembly  16 ,  18 ,  20 ,  22  comprises a grill  40  and a heater assembly  42 . Grill  40  comprises a cast iron grill plate  41  which has a TEFLON™ coated cooking surface  44  having the desired contour and surface pattern according to the food item to be cooked, and attached leaf spring  45 . Heater assembly  42  has an electric heating element  44  connected to electrical terminals  46 ,  48  through which the electrical supply to heating element  44  is provided, heat transfer plate  50  and element shield  52 . Electric heating element  44  is tightly sandwiched between heat transfer plate  50  and element shield  52  by bolts  53 . Lower cooking plate assemblies  18 ,  20  are mounted on posts  54 ,  56  secured to housing  38 . The heater assemblies  42  of upper cooking plate assemblies  16 ,  18  are each secured to a top cover  58  which in turn is pivotally connected on axle  65  through aperture  59  to arms  24  or  26 . The heater assemblies  42  are secured to top covers  58  by bolts extending through holes  70  in spacers  72  and extending into threaded holes  74  in heat transfer plate  50 . A thermocouple temperature sensor  60  extends through element shield  52  to sense the temperature of the grill plate  41 . 
     As illustrated in  FIG. 12 , leaf spring  45  is cruciform in shape with four arms  47 , and is secured centrally to circular boss  43  of grill plate  41  by screw  49 . The outer ends of arms  47  are free to flex vertically. As shown in  FIG. 13 , heater assembly  42  is positioned over grill  40  so that arms  47  extend through slots  59  of heat transfer plate  50  to the position shown in  FIG. 14 . An ear  37  on grill plate  41  can be used to orient one grill plate  41  with respect to the opposite plate  41 . Grill  40  is then rotated counterclockwise about 20 degrees relative to the heater assembly  42 , causing arms  47  of spring  45  to ride over and bear down on the upper surface of heat transfer plate  50  until the position shown in  FIG. 15  is reached and domes  66  on the heat transfer plate pop into detents  68  in arms  47 . Alternatively the domes may be in the ends of arms  47  and the detents in the surface of the heat transfer plate  50 . 
     Grill  40  can be readily removed for cleaning by rotating the grill  40  clockwise, with reference to  FIG. 15 , until arms  47  are aligned with slots  59  of heat transfer plate  50 , to the position shown in  FIG. 14  and then separating the grill  40  from heating element  42 . In this way the grills are readily removable and replaceable, yet are securely held to the appliance when installed, and the connecting mechanism is not exposed to the cooking environment and so does not become caked with food or grease. 
     As will be apparent to those skilled in the art in the light of the foregoing disclosure, many alterations and modifications are possible in the practice of this invention without departing from the spirit or scope thereof. Accordingly, the scope of the invention is to be construed in accordance with the substance defined by the following claims.