Patent Document

CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims the benefit of U.S. Provisional Patent Application Ser. No. 60/793,251 filed Apr. 20, 2006 entitled “French Door Cooking Appliance Closure System.” 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention pertains to the art of cooking appliances and, more particularly, to a door linkage system for an oven having French-style doors. Even more specifically, the invention is directed to a French-style door seal mounting and timing arrangement designed to minimize seal gasket wear. 
     2. Discussion of the Prior Art 
     It is widely known to provide a cooking appliance, such as an oven range or a wall oven, with a single, generally rectangularly shaped door that pivots about a horizontal axis. That is, a top portion of the oven door is pulled outward from the appliance about horizontally disposed hinges and lowered into a horizontal position to provide access to the oven cavity. While this type of oven door has found wide spread use, it is not entirely satisfactory for every application. For instance, an oven door that rotates about a horizontal axis projects outward from the appliance a considerable distance. This distance must be taken into consideration when deciding where to locate the appliance in the kitchen. Otherwise, the opened door could interfere with traffic patterns in the kitchen or with access to other cabinetry. In addition, such an oven door may require a consumer to stand at a side of the appliance to fully access the oven cavity. In order to address this problem, some manufacturers provide their ovens with one or more doors that swing open about substantially vertical axes. 
     Incorporating French-style doors into cooking appliances is also known in the art. An oven employing French-style doors will typically include a linkage that translates linearly so as to cause both of the doors to open or close when either one of the doors is operated. In this manner, the doors can be operated with only one hand, leaving the other hand free to hold a food item. While this type of door arrangement does address many of the shortcomings associated with horizontally swinging doors, French-style doors include several shortcomings of their own. For example, proper door sealing to avoid excessive heat loss from the oven cavity is an important concern. In at least arrangements employing doors which interengage when closed, in order for the doors to close and seal properly, one of the doors must lag relative to the other. In this manner, a proper seal can be maintained about the oven cavity without requiring a consumer to close each of the doors separately. Moreover, the linkage must properly retain the doors in the closed position in order to ensure that hot oven gases do not escape. Other areas of concern include providing end stops or detents so that the doors do not inadvertently swing shut. 
     The timing of the doors is actually crucial to the sealing properties of the cooking appliance. In particular, if the timing is off, undue seal wear can occur, resulting in undesirable heat losses from the oven cavity during use of the appliance. Known in the art is the use of stainless door wipers. These wipers are resilient, but do not follow contours easily and are prone to have gaps at their ends. Typically, a continuous glass fiber based seal is employed to close these corner gaps in order to maintain a tighter seal between the oven cavity and the door, while also being easier to install. Certain other types of known seals, such as silicone gaskets, will not stand up to self clean temperatures. Attempts have actually been made to provide silicone gaskets on the inside edges of both doors with a door timing wherein both doors are matched in their opening positions. Generally the consumer will open the doors using one handle. This biases the door timing mechanism, causing one door to move first and the gaskets to slide against each other. Simply stated, a fiber based seal will not withstand this wear. Improved quality in the mechanism could reduce the wear but is considered to be too expensive. 
     Therefore, despite the existence of French-style doors employed in cooking appliances of the prior art, there still exists a need for a French-style oven door mounting and timing system which provides for minimal wear on the gasket or sealing arrangement. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to a closure system for a cooking appliance including an oven cavity closed by a pair of laterally spaced, French-style doors. In accordance with the invention, the cooking appliance includes a cabinet shell and an oven cavity arranged within the cabinet shell, with the oven cavity having top, bottom, rear and opposing side walls that collectively define a frontal opening. The cooking appliance is provided with first and second doors that are pivotally mounted relative to the cabinet shell for selectively closing the frontal opening of the oven cavity. More specifically, the first and second doors constitute French-style doors that open about substantially vertical axes. 
     The first and second doors are interconnected through the door linkage system. More specifically, the door linkage system interconnects each of the first and second doors to one another, as well as with the cabinet shell. The door linkage system includes a first door control arm having a first end, which is pivotally mounted to the first door, and a second end. The door linkage system also includes a second door control arm having a first end, which is pivotally mounted to the second door, extending to a second end that is pivotally connected to the second end of the first door control arm. 
     The second ends of the first and second door control arms are mounted in such a manner so as to travel in arcuate paths when either one of the first and second doors is operated. More specifically, when one of the first and second doors is moved in either an opening or a closing direction, the second ends of the first and second door control arms travel over the arcuate paths, causing the other of the first and second doors to move in a corresponding direction. 
     At least one of the door control arms has associated therewith a camming surface upon which rides a corresponding cam follower as the doors transition between open and closed positions. The overall cam follower arrangement provides a sealing force to the first and second doors in the closed position. Additionally, the camming surface is provided with a plurality of detents that establish various, selectable positions for the doors. That is, the detents engage with the cam followers in order to selectively retain the first and second doors at any one of various locations ranging from a fully open position to a fully closed position, with at least one detent residing at the fully open position to ensure that the first and second doors do not inadvertently swing closed. 
     The first and second control arms are operatively connected to a support bracket through a linkage control arm. The linkage control arm establishes the arcuate path tracked by first and second ends of the door control arms, as well as a particular timing of the doors. With this arrangement, as the doors transition between the open and closed positions, the linkage control arm engages the cam follower. The cam follower travels along the camming surface to provide for a smooth transition. 
     Each of the doors has an associated gasket for use in sealing the oven cavity when the doors are closed. In accordance with the invention, one of the doors is provided with an annular gasket, while the other door essentially incorporates a less that fully annular, preferably 3-sided, gasket. Most preferably, a three-quarter gasket is employed. With this arrangement, each of the gaskets has three sides adapted to seal against the cabinet shell, while the fourth side of the first gasket is adapted to seal against an extension provided on the other door. An important aspect of the invention is to minimize abrasion on the first gasket by designing both the gasket contact point or line, and the door timing so as to produce a contact arrangement similar to that exhibited with standard single door units. 
     In connection with the invention, the gasket configurations and constructions, along with the construction and operation of the door linkage system, combine to provide a synergistic effect in minimizing potential wearing of the seal arrangement. To this end, the timing of the opening and closing of the doors is important. The door linkage system overcomes an issue of slop in the mechanism by intentionally moving one door farther than the other when the doors are first opened. Instead of the doors opening evenly, one door initially moves significantly farther than the other, breaking the contact between the first gasket and a mating portion of the other door. In the most preferred form of the invention, the oven cavity/cabinet shell, as well as the door extension, is provided with a porcelain coating. With this construction, each of the gaskets is only seated against porcelain coated surfaces to minimize wear caused by surface roughness. 
     In accordance with the invention, the annular gasket does not make contact with the side of the other door panel. If placed in this position, the gasket would be compressed as the doors are opened, loose its ability to return to shape after being subjected to the high temperatures of several self cleaning operations, and not return to a shape needed for properly sealing the doors. Instead, the fourth side, or center seal, of the gasket on the first door contacts the extension of the opposite door. This extension places the contact surface mostly behind the gasket. As the doors are opened, the timing established by the linkage system pulls the gasket away from the sealing surface behind it. By breaking the contact early in the door opening process, the seal is saved from any unnecessary crushing or abrasion. 
     An additional feature of the invention is that different rates of movement are imparted to the doors when nearing closed positions in order to help assure good contact of the center seal. The timing established by the linkage system will continue to pull the doors closed until the center seal or gasket makes contact, thereby providing a mechanically advantaged force to balance a force applied by a door closure spring. In any case, additional objects, features and advantages of the present invention will become more readily apparent from the following detailed description of preferred embodiments when taken in conjunction with the drawings wherein like reference numerals refer to corresponding parts in the several views. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a cooking appliance including French-style doors constructed in accordance with the invention, with the doors being shown in a fully closed position; 
         FIG. 2  is a perspective view of the cooking appliance of  FIG. 1  showing the French-style doors in a fully open position; 
         FIG. 3  is a perspective view of another cooking appliance including French-style doors constructed in accordance with the invention, with the doors being shown in a fully closed position; 
         FIG. 4  is an upper perspective view of a door linkage system constructed in accordance with one embodiment of the present invention with the doors in a closed position; 
         FIG. 5  is an upper perspective view of the door linkage system of  FIG. 4  with the doors moving towards an open position; 
         FIG. 6  is an upper perspective view of a door linkage system of  FIG. 5  with the doors in a fully open position; 
         FIG. 7  is a top view of a door linkage system used to control the doors of the cooking appliance of  FIG. 1  or  3  illustrated with the French-style doors in a fully closed position; 
         FIG. 8  is a top view of the door and linkage system similar to  FIG. 5 , but with the doors open a small amount; 
         FIG. 9  is a top view similar to  FIG. 8 , but with the doors opened a slightly greater amount, such as about 3-5°; 
         FIG. 10  is a top view of the door linkage system of  FIG. 9  with the doors moved further towards the fully open position; 
         FIG. 11  is a top view of the door linkage system of  FIG. 10  with the doors moved even further towards the fully open position; 
         FIG. 12  shows an oven cavity of the cooking appliance exposed as the doors are fully opened; 
         FIG. 13  is an enlarged perspective view of one of the doors of the cooking appliance of  FIG. 12 , particularly illustrating the construction of a first gasket; 
         FIG. 14  is an enlarged perspective view of another one of the doors of the cooking appliance of  FIG. 12 , particularly illustrating the construction of a second gasket; and 
         FIG. 15  shows the cooking appliance of  FIG. 12  in another perspective view with the doors open. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     With initial reference to  FIGS. 1 and 2 , a cooking appliance constructed in accordance with the present invention is generally indicated at  2 . As depicted, cooking appliance  2  constitutes a wall oven. However, it should be understood that the present invention is not limited to this particular model type and can be incorporated into various types of oven configurations, e.g., cabinet mounted ovens, as well as both slide-in and free-standing ranges. In any event, in the embodiment shown, cooking appliance  2  constitutes a single wall oven unit including a frame  4  (best seen in  FIG. 3 ) that supports, at least in part, an oven cavity  6 . Oven cavity  6  includes a top wall  8 , a bottom wall  9 , a rear wall  10  and opposing side walls  11  and  12  that collectively define a frontal opening  14 . In a manner known in the art, frontal opening  14  is surrounded by a face frame portion  17  which provides an overall aesthetic finish to cooking appliance  2 . Preferably, face frame portion  17  is provided with first and second openings  19  and  20  which, as will be discussed more fully below, lead to frame  4 . Face frame portion  17  is also provided with additional openings  23  and  24  that form part of an overall airflow system of cooking appliance  2 . 
     In a manner known in the art, cooking appliance  2  includes a control panel  38  having a plurality of control elements. In accordance with the embodiment shown, the control elements are constituted by first, second and third sets of oven control buttons  40 - 42 , as well as a numeric pad  43 . Control panel  38  is adapted to be used to input desired cooking parameters and establish operating conditions for cooking appliance  2 . More specifically, first, second and third sets of control buttons  40 - 42 , in combination with numeric pad  43  and a display  45 , enable a user to establish particular cooking operations that are performed within oven cavity  6 . As the oven control is known in the art and does not form part of the present invention, it will not be discussed further herein. 
     In accordance with the invention, cooking appliance  2  is provided with French-style doors that are adapted to selectively seal across frontal opening  14 . More specifically, cooking appliance  2  includes a first door  52  and a second door  53  that are pivotally mounted relative to frame  4  and adapted to be moved from a fully closed position, as represented in  FIG. 1 , to a fully open position, as represented in  FIG. 2 , to provide access to oven cavity  6 . As will be clear from the remaining figures, doors  52  and  53  swing outward about substantially vertical axes established by upper hinges  54  and  55  ( FIG. 4 ) and lower hinges (not shown). 
     In a manner known in the art, each door  52 ,  53  is provided with a corresponding outer panel  57 ,  58  having a respective central transparent zone or window  59 ,  60 . In addition, each door  52 ,  53  is provided with a corresponding handle  61 ,  62  that enables a consumer to shift doors  52  and  53  between open and closed positions. In order to provide a proper seal about frontal opening  14 , each door  52 ,  53  includes an inner panel  65 ,  66  about which extends a peripheral seal or gasket as discussed in detail below. In addition, first door  52  is provided with a flange  67  that serves as an intermediate sealing surface for second door  53 . That is, when both first and second doors  52  and  53  are moved to the closed position of  FIG. 1 , flange  67  traverses an intermediate gap or opening (not separately labeled) laterally between doors  52  and  53 . Although not part of the present invention, doors  52  and  53  are shown to include a plurality of openings indicated generally at  70  and  71  on inner panels  65  and  66 . Openings  70  and  71  allow a flow of air to pass from within doors  52  and  53  into openings  23  and  24  and around oven cavity  6 . The airflow minimizes the conduction of heat from oven cavity  6  to outer panels  57  and  58  of doors  52  and  53 . In any event, in order to provide a consumer easy access to oven cavity  6 , cooking appliance  2  is provided with a door linkage system  68  ( FIG. 2 ) that interconnects first and second doors  52  and  53 . Linkage system  68  operates such that movement of either one of first and second door  52  and  53  causes the other one of first and second doors  52  and  53  to move or shift in a corresponding manner as will be detailed more fully below. 
       FIG. 3  is presented to simply illustrate that the overall design of the cooking appliance can vary in accordance with the invention. In particular, this figure indicates control panel  38   a  having control knobs  73  and  74  which, along with an enlarged display  43   a , are used in programming the appliance for a cooking operation. In any case, various configurations can be employed without departing from the invention as will become fully evident from the following invention description. 
     Reference will now be made to  FIGS. 4-6  in describing a linkage system  200  constructed in accordance with an embodiment of the invention. Linkage system  200  includes a first control arm  210  having a first end  211  which is pivotally connected to door  52  and extends to a second end  212  through an intermediate portion  213 . In addition, linkage system  200  includes a second control arm  218  having a first end  219  which is pivotally connected to door  53  and extends to a second end  220  through an intermediate portion  221 . In a manner discussed more fully below, first and second control arms  210  and  218  interconnect first and second doors  52  and  53  such that operation of one door, for example door  52 , will result in a similar movement to second door  53 . 
     In accordance with the invention, linkage system  200  includes a stationary control arm or support member  237  having a first end  238  fixedly mounted relative to frame  4  and extending to a second end  239  through an intermediate portion  240 . In a manner which will be discussed more fully below, a section of intermediate portion  240  includes a camming surface  242 . First and second control arms  210  and  218  are operatively connected to support member  237  through a linkage control arm  244 . More specifically, linkage control arm  244  includes a first end  247  pivotally connected to intermediate portion  240  of support member  237  at a pivot point or axis  249 . First end  247  extends to a second end  254  through an intermediate portion  258 . For reasons which will be described more fully below, second end  254  is provided with a plurality of openings, indicated generally at  260 . 
     In accordance with this form of the invention, linkage system  200  includes a tensioning bracket  284  connected to linkage control arm  244  through a pivot pin  285 . Tensioning bracket  284  includes a first end  286  that extends to a second end  287 . Second end  287  is provided with a plurality of apertures, indicated generally at  289 . With this arrangement, a spring  292  is fastened at one of the plurality of apertures  289  and one of the plurality of openings  260  on linkage control arm  244  to provide tension to first and second control arms  210  and  218 . More specifically, by selecting between the plurality of apertures  289  and/or plurality of openings  260 , a desired tension can be placed on linkage control arm  244 . In any event, tensioning bracket  284  is shown to include a cam follower  294  provided at first end  286 . As will be described more fully below, cam follower  294  cooperates with camming surface  242  and linkage control arm  244  to guide doors  52  and  53  between a closed position, as represented in  FIG. 4 , through an intermediate position, as represented in  FIG. 5 , to a fully open position as represented in  FIG. 6 . 
     As best shown in  FIG. 4 , when doors  52  and  53  are in the closed position, linkage control arm  244  rests upon cam follower  294  with the tension in spring  292  being at a minimum level. As doors  52  and  53  transition towards the intermediate position, linkage control arm  244 , through a force provided by first and/or second door control arms  210  and  218 , transitions along an arcuate path causing cam follower  294  to travel along camming surface  242 . In addition, spring  292  provides tension to first and second control arms  210  and  218  to ensure that doors  52  and  53  do not swing open freely. However, once cam follower  294  passes over a high portion (not separately labeled) of camming surface  242 , tensioning bracket  284  aids in shifting doors  52  and  53  to the fully open position. Once doors  52  and  53  reach the fully open position as shown in  FIG. 6 , cam follower  294  rests at a bottom portion or notch section  304  of camming surface  242 . By positioning cam follower  294  in notch section  304 , doors  52  and  53  are maintained in a fully open position allowing a consumer to freely introduce a food item into oven cavity  6 . 
     At this point, it is possible to shift doors  52  and  53  to the closed position as represented in  FIG. 4 . Accordingly, a consumer need operate either door  52  and/or  53  to close cooking appliance  2 . That is, by operating either door  52  or  53 , a respective control arm  210 ,  218  exerts a force on linkage control arm  244 . Linkage control arm  244  is guided back to the home position, with cam follower  294  moving along camming surface  242 . More specifically, tensioning bracket  284 , in combination with cam follower  294 , ensures that doors  52  and  53  transition smoothly towards the closed position. As cam follower  294  transitions over a top portion (not separately labeled) of camming surface  242 , spring  292  pulling on linkage control member  244  aids in the overall closing and sealing of doors  52  and  53 . 
     At this point, it should be understood that various linkage systems can be designed to carry out the required closure timing of the French-style doors for the cooking appliance of the invention. For instance, the linkage systems disclosed in pending U.S. patent application Ser. No. 11/206,219 entitled “Door Linkage System for an Oven Having French-Style Doors”, the disclosure of which is hereby incorporated by reference, could be employed. Even if the linkage system is varied, it is important to provide flexibility for setting the particular timing of the closing of the doors in order to prevent undue wear on door seals. 
     This advantageous feature of the invention is best seen in connection with  FIGS. 7-11  where like reference numbers represent corresponding parts to those disclosed above. In  FIG. 7 , doors  52  and  53  are fully closed, with an inner portion  300  of a first door seal or gasket  305  provided about door  52  engaging a portion of door  53 . The embodiment depicted illustrates door  53  being provided with a lateral extension member  315  against which gasket  305  seats. However, it should be understood that door  53  could itself be formed for sealing engagement by gasket  305 . The preferred configuration of gasket  305 , as well as a gasket  335  provided on door  53 , will be detailed more fully below with reference to  FIGS. 12-15  where like reference numbers represent similar parts as discussed above. At this point, it is important to note that, as doors  52  and  53  are opened, only a very limited relative movement is required to unseat inner portion  300  of gasket  305 . Actually, as shown in  FIG. 8 , only a few degrees of door movement, preferably 3-5° of movement, is required for this disengagement to occur. As the contact has been broken at this initial stage, no potential for any wear or abrasion of gasket  305  will occur throughout the remainder of the door opening process. In any case,  FIGS. 9-11  show further opening stages as well wherein, advantageously, gasket  305  is not touched by any other surface through the door movement range. In fact, both gaskets  305  and  335  are cleared from further surface contact with a relatively minimum door opening range of movement as clearly illustrated in these figures. As previously stated, avoiding unnecessary contact with gaskets  305  and  335  minimizes potential wear and abrasion so as to significantly increase the life and effectiveness of each gasket  305 ,  335 . However, it is the significant wear and abrasion that can occur between gasket  305  and door  53  that is particularly avoided. 
     As clearly shown in  FIGS. 12-15 , gasket  305  preferably extends annularly about an entire inner peripheral portion  350  of door  52 . In the embodiment shown, gasket  305  includes opposing, substantially parallel gasket side portions  355 ,  356  and  357 ,  358 , with side or center portion  357  actually being adapted to engage door  53 . On the other hand, gasket  335  only extends about three-fourths of an inner peripheral portion  375  of door  53 . That is, gasket  335  includes an upper and lower, substantially parallel gasket side portions  377  and  378  that are joined by a single gasket side portion  379 . Therefore, upper and lower side portions  377  and  378  terminate at upper and lower portions  380  and  381  of extension member  315 . With this arrangement, a tight seal can be established without seal-to-seal contact and only one seal member, i.e., gasket  305 , having to engage the opposing door, i.e., door  53 . 
     Based on this construction, the particular structure and arrangement of gaskets  305  and  335  themselves provide for enhanced seal life. In particular, door linkage system  200  of the present invention overcomes an issue of slop in the mechanism by intentionally moving one of doors  52  and  53  farther than the other of doors  52  and  53  when doors are first opened. For example, instead of doors  52  and  53  opening evenly, door  52  initially moves significantly farther than door  53 , breaking contact between gasket  305  and a mating portion or extension member  315  of door  53 . In the most preferred form of the invention, the oven cavity  6 /cabinet shell  4 , as well as extension member  315 , is provided with a porcelain coating. With this construction, each of gaskets  305 ,  335  is only seated against porcelain coated surfaces to minimize wear caused by surface roughness. 
     As discussed above, annular gasket  305 , or more particularly gasket side member  357 , does not make contact with the side (not separately labeled) of door  53 . Instead, the gasket side member  357  of gasket  305  contacts extension member  315  of door  53 . Extension member  315  places the contact surface mostly behind gasket  305 . As doors  52  and  53  are opened, the timing established by linkage system  200  pulls gasket  305  away from extension member  315 . By breaking the contact early in the door opening process, gasket  305  is saved from any unnecessary crushing or abrasion. 
     An additional feature of the invention is that different rates of movement are imparted to doors  52  and  53  when nearing closed positions in order to help assure good contact of the center seal. That is, the timing established by linkage system  200  continues to pull doors  52  and  53  closed until gasket side portion  357  makes contact with extension member  315 , thereby providing a mechanically advantaged force to balance a force applied by a door closure spring (not separately labeled). In any case, although described with reference to preferred embodiments of the present invention, it should be readily apparent to one of ordinary skill in the art that various changes and/or modifications can be made to the invention without departing from the spirit thereof.

Technology Category: 2