Patent Publication Number: US-6698418-B2

Title: Oven door latch assembly having side mounted motor

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This patent application claims priority to provisional patent application serial No. 60/315,498 filed Aug. 28, 2001 entitled “Oven Door Latch Assembly Having Side Mounted Motor” which is fully incorporated by reference herein. 
    
    
     FIELD OF THE INVENTION 
     This application relates to a motorized oven door latch assembly for locking an oven door in a closed position when the oven is in a self-cleaning mode. 
     BACKGROUND OF THE INVENTION 
     Self-cleaning ovens which are incorporated into self-standing ranges are well known. Such ovens conventionally have an oven door which is hingedly secured to a range body. The oven door may be opened to gain access to an oven cavity. The oven door may also be closed to close the opening for cooking objects placed in the cavity or cleaning the cavity. One or more heating elements reside in the oven cavity for cooking purposes. 
     Motorized latches which are used to lock oven doors in a closed position so that the oven cavity may be self cleaned are well known. U.S. Pat. No. 3,859,979 and U.S. Pat. No. RE. 27,545 and U.S. Pat. No. 4,374,320 all disclose such motorized self-cleaning oven door latches. Such oven door latches are activated by a rotary motor located at the rearward portion of the range above the oven. Activation of the motor causes a rod to translate which causes a latch at the front of the rod to engage the oven door so that the oven door may not be opened. After the cleaning has occurred, the motor is reactivated, causing the latch at the front of the rod to disengage the oven door so that the oven door may be opened. 
     One disadvantage with oven door latch assemblies having motors located rearwardly of the oven cavity is that the high temperatures required for oven cleaning may damage the motor and/or associated electrical components such as switches. Therefore, a need exists for an oven door latch assembly having a motor which is located such that its exposure to temperature is minimized. It has further been an objective of the present invention to provide an oven door latch which is driven by a motor located to the side of the oven cavity. 
     SUMMARY OF THE INVENTION 
     The invention of this application which accomplishes these objectives comprises a motorized door latch assembly for locking an oven door in a closed and sealed position so as to close an oven cavity for purposes of cleaning the oven cavity. The oven door is hingedly mounted on a range body and moveable between an open position, a closed position and a closed and sealed position. 
     The door latch assembly comprises a mounting plate supported by the range body beside the oven cavity and extending generally horizontally. Fixedly secured to the mounting plate is a driver such as a motor. The driver need not be fixedly secured to the mounting plate; it may be at any desired location. However, the driver or motor is preferably located beside the range or oven cavity to reduce the amount of heat to which the motor is exposed. The motor rotatively drives a cam, operatively associated with the motor. 
     A drive member or latch rod, having a pair of opposed ends, extends between the cam and an L-shaped link pivotally secured to the mounting plate. The latch rod has a first end secured to the rotatable cam and a second end secured to the L-shaped link. Rotation of the cam causes the latch rod to translate generally from side to side. Other devices, such as for example a solenoid, may be used to cause the latch rod to translate. 
     A latch plate, having a hook at one end for engaging the oven door, is secured to the L-shaped link at the other end. The latch plate has an opening therethrough capturing a pin that extends upwardly from the mounting plate. The size and configuration of the opening and location of the pin restrict the movement of the latch plate so as to move the latch plate between three desired positions. 
     In operation, rotation of the cam by activation of the motor causes the latch rod to translate generally from side to side and causes the latch plate to move between three positions: a first position, a second position and a third position. In the first position, the latch plate is located such that the oven door may be opened. Upon translation of the latch rod, the latch plate moves to a second position in which the hook of the latch plate engages the oven door to prevent the oven door from being opened. In the third position, the latch plate is pulled inwardly by the latch rod, pulling the oven door into a locked and sealed position. Notably, the direction of translation when the oven door is pulled into the locked and sealed position, is substantially nonparallel to the direction in which the latch rod is translated by the motor, through action of the L-shaped link. 
     A biaser extends between a fixed point on the mounting plate and the latch plate so as to bias the latch plate towards the second position described hereinabove. In the event of a failure while the oven is in a self-cleaning mode and the latch plate is in its third position, i.e. while the door is locked and sealed, a user, using a pry bar tool, may exert pressure on the hook of the latch plate causing the latch plate to rotate about the pin of the mounting plate toward the first position. With the latch plate pulled over to its first position the oven door may be opened without having to call a service technician and/or take the oven apart. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective of a self-standing range with a portion cut away, with a latch built in accordance with the present invention. 
     FIG. 2 is an enlarged view of a portion of the front edge of the range of FIG. 1 with a pry bar-type tool illustrated being used to open the oven door. 
     FIG. 3 is a top view of the motorized oven door latch assembly of the present invention, the latch plate being illustrated in an unlocked position. 
     FIG. 4 is a top view illustrating the latch plate in a locked and sealed position. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     Referring to the drawings, and particularly to FIG. 1, there is illustrated a self-standing range  10  including a pyrolytic self-cleaning oven  12  on top of which are a plurality of burners  14  as is conventional. The range  10  comprises a range body  16  having a pair of side walls  18 , a front wall  19 , a back wall  20  (see FIG. 1) and a top  21 . Spaced a fixed distance below the top  21  of the range body  16  is an oven top wall  22 . An oven cavity  24  inside which resides one or more heating elements (not shown) is defined by the oven top wall  22 , side walls  18  of the range body, a cavity back wall (not shown) and a bottom  27 . An oven door  26  having a handle  28  and a window  30  is hingedly mounted to the front wall  19  of the range body so that a user pulling on the handle  28  will cause the oven door  26  to hingedly open about an horizontal axis  32  in order to move the door  26  between a closed position as shown in FIG.  1  and an open position. As best illustrated in FIG. 2, the oven door  26  has a thickness T defined between a back wall  34  and a front wall  36  between which is insulation  38 . 
     Illustrated within range  10  above top wall  22  and below top  21  of the range body  16 , is a latch assembly  40  mounted to the range body and/or the walls  21  and  22 , and positioned to latch door  26  in a closed and sealed position by the action of the front end  66  of a latch plate  42 . Further detail on the structure of assembly  40  and the interaction of latch plate  42  with oven door  26  will be provided below. 
     FIG. 1 illustrates that the latch assembly may be located in an alternative position  40 ′ adjacent to either side wall  18  of the oven, in which case latch plate  42  engages to a side of oven door  26  in a similar manner. Note that in both the position illustrated in solid lines in FIG. 1, and in the alternative position  40 ′ illustrated in FIG. 1, the latch rod  56  extending between the motor and latch plate moves along a direction that is roughly orthogonal to the direction in which the latch plate pulls the oven door when moving to the locked and sealed position. The structure of the latch assembly  40  facilitates this operation regardless of the position of that assembly within the oven. 
     While the latch assembly may be horizontally and vertically positioned as shown in FIG. 1, it may also be positioned in an angled orientation, in which case the direction of motion of the latch rod  56 , while still substantially nonparallel to the direction of pull in of the latch plate, is not necessarily orthogonal to the direction of pull in. The structure of the latch assembly, as elaborated below, facilitates installations where there is a substantially nonparallel relationship between the direction of motion of the latch rod  56  and the pull in direction, such as at angles of greater than 30, 45 or 60 degrees. 
     It will be noted that in either the top-mounted position shown in FIG. 1, or in a side mounted position shown at  40 ′ in FIG. 1, the position of the motor  44  within the latch assembly is to the side of the oven and thus somewhat removed from heat generated in the oven. The latch assembly, by permitting a nonparallel relationship between the direction of motion of the latch rod  56  and the pull-in direction, permits placement of the motor in a wide variety of locations so as to avoid the damaging effects of exposure to heat. 
     As best illustrated in FIGS. 2-4, the door latch assembly  40  functions to lock the oven door  26  in a closed and sealed position so that the oven door  26  may not be opened e.g. when the oven is in a self-cleaning mode. The door latch assembly  40  comprises multiple components which work together to move a latch plate  42 , best illustrated in FIG. 2, between three different positions so that the oven door may be opened when the latch plate is in a first position and the oven door may not be opened when the latch plate is in either its second or third positions (except with the use of a pry bar-type device or tool  43 ). 
     The door latch assembly  40  comprises a motor  44  activated by power lines  46  and located adjacent the oven cavity  24 . One type of motor which has proven satisfactory is 120 volts AC; 60 Hz having a speed of 3.2 rpm. A cam  48  is secured to the motor  44  such that rotation of the motor causes the cam  48  to rotate about a vertical axis. 
     A mounting plate  50  extends generally from the left side of the range to the right side of the range and is secured to the front wall  19  of the range with fasteners  52  (see FIG.  2 ). In the embodiment illustrated in solid lines in FIG. 1, the mounting plate  50  is located below the top  21  of the range and above the top wall  22  of the oven cavity. An opening  54  in the mounting plate  50  (see FIG. 2) allows the cam  48  to freely rotate when activated by the motor  44 . As illustrated in FIG. 2, the cam  48  is located above the mounting plate  50  and the motor  44  is located below the mounting plate  50 . The mounting plate  50  is supported by the range body above the oven cavity  24  in a generally horizontal orientation as seen in FIGS. 1 and 2. Although FIG. 1 illustrates the mounting plate  50  being located in a particular orientation, the mounting plate  50  may be placed in other locations as well without departing from the spirit of the invention of this application. 
     As best illustrated in FIG. 2, the mounting plate  50  has a vertically oriented front lip  51 . The front lip  51  abuts the front wall  19  of the range body and has a pair of holes  53  therein through which the fasteners  52  pass to secure the front lip  51  of the mounting plate  50  to the front wall  19  of the range body. Additionally, the front lip  51  of the mounting plate has a generally rectangular opening  55  through which the latch plate  42  passes. 
     As best illustrated in FIG. 2, an opening or guide  57  is located through the latch plate  42 . The opening  57  is an opening of a particular configuration illustrated in detail in FIG. 2 comprising a generally triangular shaped rear portion  57   a  including a diagonal surface  59  and a generally square portion  57   b  having a stopping surface  61 . The size and configuration of the opening  57  limits the movement of the latch plate  42  in a manner described in more detail below. 
     As best illustrated in FIGS. 2-4, a latch rod  56  extends between the cam  48  and a generally L-shaped link  70 , extending generally from side to side of the range. The generally L-shaped link  70  is pivotally secured to the mounting plate  50  at location  71 . The latch rod  56  has a first end  58  which is secured to the cam  48  and a second end  60  which is secured to the link  70  at location  72  in a manner which will be described in more detail below. The latch rod  56  is located generally above the mounting plate  50  and moves in a generally linear manner depicted by the arrows  62  (shown in FIGS. 3 and 4) as the cam  48  rotates. 
     Another component of the door latch assembly  40  is the latch plate  42  best illustrated in FIG.  2 . The latch plate  42  has a hook  64  located at a front end  66 , and is secured to L-shaped link  70  at  73 . Between the front and back ends the opening  57  of the latch plate  42  is adapted to receive a pin  74 . The pin  74  is secured to the mounting plate  50  and extends upwardly therefrom in a fixed location. The pin  74  remains inside the opening  57  as the latch plate  42  moves between positions. Alternatively, the pin may be secured to the latch plate and the opening formed in the mounting plate to restrict movement of the latch plate as the latch plate moves between positions. 
     As best illustrated in FIGS. 2-4, the latch plate  42  is movable between three positions: a first position illustrated in FIG. 3, a second position illustrated in FIG. 2 and a third position illustrated in FIG. 4 (in which the door is locked and sealed). The first position of the latch plate  42  is shown in dashed lines in FIG. 2 (to the left). In this first position, the hook  64  of the latch plate  42  is aligned with an opening  39  in the back wall  39  of the oven door (see FIG.  2 ). With the latch plate  42  in this first position, the oven door  26  may be freely opened, the hook  64  of the latch plate  42  passing through the opening  39  in the oven door  26 . As the latch rod  56  translates rearwardly due to activation of the motor and consequent rotation of the cam  48 , the latch plate  42  moves to its second position, which is shown in solid lines in FIG.  2 . In this position, the oven door  26  may not be opened because the hook  64  of the latch plate  42  catches the back wall  34  of the oven door  26 . Upon further rearward translation of the latch rod  56 , the latch plate  42  is pulled rearwardly in the direction of arrow  79  to its third position (illustrated in FIG. 4) in which the oven door  26  is locked and sealed. In this position, the oven door  26  is correctly sealed and seated so as to provide a tight seal for the oven cleaning process. 
     As best illustrated in FIG. 2, the second end  60  of the latch rod  56  comprises a vertical section  80  and a horizontal section  82  which terminates in an end  83 . The hole  68  in the link  70  is sized so as to have a diameter slightly larger than the diameter of the vertical section  80  of the latch rod  56  so that the vertical section  80  of the latch rod  56  passes through the hole  68  in the link  70 , the horizontal section  82  of the latch rod  56  being located below the link  70 . 
     In order to bias the latch plate  42  toward its second position, a biaser  85  (best illustrated in FIG. 2) extends between a bracket  87  fixedly secured to the front of the mounting plate  50  and a finger  89  of the latch plate  42 . The finger  89  of the latch plate extends vertically and has a hole  90  therein through which a hook  91  of the biaser  85  passes in order to secure one end of the biaser  85  to the latch plate. The other end of the biaser  85  has a hook  93  which passes through a hole in the bracket  87 . Although the biaser  85  is illustrated as being a spring, the biaser  85  may be any other biasing-type mechanism and may be secured at either end with structures other than hooks to the latch plate  42  and to the bracket  87 , respectively. 
     In operation, upon activation of the motor, the cam  48  rotates, causing the latch rod  56  to translate along the direction of arrows  62 . See FIGS. 3 and 4. Upon rearward translation of the latch rod  56 , the latch plate  42  moves from its first position  76  to its second position  77  in which the oven door is prevented from opening (See FIGS.  3  AND  4 ). Upon further translation of the latch rod, the latch plate  42  is pulled rearwardly from its second position  76  to its third position  78  in the direction of arrow  79 . The direction of arrow  79  and the direction of translation  62  of the latch rod  56  define an angle therebetween which is generally orthogonal. Depending upon the orientation of the latch rod  56 , generally L-shaped link  70  and latch plate  42 , this angle may be any angle, preferably greater than  30  degrees. When the latch plate  42  is in its third position  78  the oven door  26  is in a locked and sealed position with the back wall  34  of the oven door exerting pressure against a gasket  96  located between the oven door  26  and the front wall  19  of the range body (see FIG.  2 ). 
     In the event of an electrical or mechanical failure while the oven is in a self-cleaning mode and the oven door  26  is in a locked and sealed position, the latch rod  56  will not translate. Thus, the latch plate  42  is fixed in its third position  78 . In heretofore known range door assemblies, a service technician had to be called in order to access the latch rod  56  through the back of the range in order to open the oven door  26  so that the oven could be used for cooking. With the present invention, a pry bar-type device or tool  43  having a horizontal section  98  and a vertical section  100  may be used to open the oven door  26  without having to call a service technician and/or without having to access the oven cavity through the rear panel of the range. 
     As best illustrated in FIG. 2, the vertical section  100  of the pry bar tool  43  is moved in the direction of arrow  102  such that the vertical section  100  is pried between the oven door  26  and the front wall  19  of the range body to the right of the latch plate. By moving the tool  43  in the direction of arrow  104 , as shown in FIG. 2, pressure is exerted on the latch plate  42 , pushing the front end of the latch plate in the direction of arrow  106  (to the left), as seen in FIG. 2, towards its first position. By moving the pry bar tool  43  in this direction, the latch plate  42  is moved against the bias of the biaser  85  causing the rear of the latch plate  42  to move in a forward and sideways direction as dictated by the configuration of the guide  57  formed in the mounting plate  50 . With the latch plate  42  in its first position  76 , the oven door  26  may be opened. 
     Thus, with the present invention an operator may quickly and easily open the oven door even in the event of a mechanical or electrical failure. Consequently, the oven may be used for cooking immediately and is not inoperable for an extended period of time until a service technician comes to fix the cause of the failure. 
     While we have described one preferred embodiment of the present invention, persons skilled in the art will appreciate changes and modifications which may be made to the present invention without departing from the scope of the invention. Therefore, we do not intend to be limited except by the scope of the following claims.