Abstract:
A dishwasher is provided with an adjustable rack that can be moved upwardly and downwardly within the washing chamber to accommodate different sized objects to be washed. The lift mechanism for the rack is housed within the sidewalls of the dishwasher. The lift mechanism employs a cable system to raise both sides of the rack simultaneously, with the rack positioned within or outside the washing chamber and with the rack either loaded or unloaded. In one embodiment, the lift mechanism is manually actuated by turning a handle. In another embodiment, the lift mechanism includes an electric motor with a switch on the control panel for raising and lowering the rack.

Description:
BACKGROUND OF THE INVENTION  
       Field of the Invention  
         [0001]    Dishwashers with adjustable racks are known in the art. Typically, such adjustable racks must be empty and moved out of the washing chamber to permit the height of the rack to be adjusted. Also, the lift mechanism for adjusting the height of the rack normally occupies space within the rack, thereby decreasing the area of the rack which can be used for placing dishes, glasses, and other objects to be washed. Also, such adjustable racks normally raise or lower one side of the rack and then the other side of the rack in sequential steps.  
           [0002]    Accordingly, a primary objective of the present invention is the provision of a dishwasher having an improved adjustable rack.  
           [0003]    Another objective of the present invention is the provision of an adjustable rack for a dishwasher which can be raised and lowered when positioned in or out of the washing chamber.  
           [0004]    Another objective of the present invention is the provision of an adjustable rack for a dishwasher which can be raised and lowered when unloaded or loaded with objects to be washed.  
           [0005]    A further objective of the present invention is the provision of a dishwasher having an adjustable rack wherein the lift mechanism is housed within the sidewalls of the dishwasher.  
           [0006]    Still another objective of the present invention is the provision of a dishwasher having an adjustable rack wherein the lift mechanism does not occupy space within the rack.  
           [0007]    A further objective of the present invention is the provision of an adjustable rack for a dishwasher wherein both sides of the rack are raised or lowered simultaneously.  
           [0008]    Another objective of the present invention is the provision of a dishwasher having a rack wherein the height of the rack within the washing chamber can be manually adjusted.  
           [0009]    Still another objective of the present invention is the provision of a dishwasher having a rack wherein the height of the rack within the washing chamber can be adjusted via a switch or button on the control panel of the dishwasher.  
           [0010]    A further objective of the present invention is the provision of a dishwasher having an adjustable rack which is economical to manufacture and durable and efficient in use.  
           [0011]    These and other objectives will become apparent from the following description of the invention.  
         SUMMARY OF THE INVENTION  
         [0012]    The dishwasher of the present invention includes a washing chamber defined by opposite sidewalls, a top wall, a bottom wall, and a back wall. One or more racks are provided within the chamber for holding objects to be washed. The racks can be moved horizontally into and out of the washing chamber for loading and unloading the objects to be washed.  
           [0013]    One or more of the racks is vertically adjustable to accommodate different sized objects to be washed. A lift mechanism is provided in the opposite sidewalls of the dishwasher and is operatively connected to the adjustable rack for raising and lowering the rack. The lift mechanism includes guide tracks extending vertically in the opposite sidewalls, and guide blocks movably mounted within the guide tracks. The guide blocks are interconnected by cables such that the opposite sides of the rack are raised or lowered simultaneously. The cables are connected to a drum gear which is rotated by a worm gear. In one embodiment, the worm gear is mounted on a shaft with a handle for manually turning the worm gear to raise and lower the rack. In another embodiment, an electric motor is connected to the worm gear and to a switch on the control panel for raising and lowering the rack. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0014]    [0014]FIG. 1 is a front view of the dishwasher with the door open and the middle adjustable rack in a lower position.  
         [0015]    [0015]FIG. 2 is a schematic perspective view of the lift mechanism for the adjustable rack of the present invention.  
         [0016]    [0016]FIG. 3 is a front schematic view of the lift mechanism.  
         [0017]    [0017]FIG. 4 is a side elevation view of the left-hand portion of the lift mechanism.  
         [0018]    [0018]FIG. 5 is a side elevation view of the right hand portion of the lift mechanism.  
         [0019]    [0019]FIG. 6 is a sectional view taken along lines  6 - 6  of FIG. 5.  
         [0020]    [0020]FIG. 7 is a perspective view of the drum gear. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0021]    In the drawings, the reference numeral  10  generally designates a dishwasher. The dishwasher  10  includes a washing chamber  12  defined by opposite sidewalls  14 ,  16 , a top wall  18 , a bottom wall  20 , and a rear wall  22 . A door  24  is pivotally mounted to the dishwasher  10  for movement between open and closed positions. The dishwasher  10  includes upper and lower spray arms  26 ,  28 .  
         [0022]    As seen in FIG. 1, the dishwasher  10  includes an upper rack  30 , a lower rack  32 , and a middle rack  34 . It is understood that one of the racks can be eliminated such that the dishwasher only has two racks. Each of the racks  30 ,  32  and  34  are moveable in a horizontal plane between a position within the washing chamber  12  and a position substantially outside the washing chamber  12  for loading and unloading objects to be washed. The lower rack  32  includes wheels  36  which ride along a ledge or lip  38  adjacent the opposite sidewalls  14 ,  16  of the dishwasher  10 . The upper rack  30  includes rollers  40  which roll along guide rails  42 , which in turn can be horizontally moved between upper and lower guide rollers  44  mounted on each of the sidewalls  14 ,  16 .  
         [0023]    The above structure of the dishwasher  10  is conventional and does not constitute a part of the present invention.  
         [0024]    The present invention is directed towards the vertical adjustability of one of the racks. In the drawings and in the following description, the middle rack  34  is designated as the adjustable rack, though it is understood that the lift mechanism for adjusting the height of one of the racks can be utilized on any of the racks within the dishwasher  10 .  
         [0025]    The lift mechanism for raising and lowering the middle rack  34  is best seen in FIGS.  2 - 5  of the drawings. Generally, the lift mechanism is a cable system with an actuator for raising and lowering the middle rack  34  within the washing chamber  12 . The lift mechanism is housed within the sidewalls  14 ,  16  of the dishwasher  10 , and thus does not take up space within the rack  34 .  
         [0026]    More particularly, each sidewall  14 ,  16  has a C-shaped guide track  46 ,  47  mounted therein, respectively. Slidably mounted within each guide track  46 ,  47  is a guide block  48 ,  49 , respectively, which are movable upwardly and downwardly within the guide tracks  46 ,  47 . An arm  50  is fixed to and cantilevered from each guide block  48 ,  49 . The arms reside within the washing chamber  12  adjacent the opposite sidewalls  14 ,  16 . Each arm  50  includes four rollers  52  which receive guide rails  54 . The rack  34  includes rollers  56  rollably mounted within the guide rails  54 . Accordingly, the rollers  56  can roll horizontally through the guide rails  54 , which in turn can roll along the rollers  52  such that the middle rack  34  can be moved into and out of the washing chamber  12 .  
         [0027]    The lift mechanism includes a set of cables  58 ,  60 ,  62 . The first cable  58  has a first end  64  secured to a drum gear  66  rotatably mounted within the left sidewall  14 . The cable  58  wraps around the drum gear  56  in a first circumferential groove  68 , and has a second end  70  secured to the top of the guide block  48 . The second cable  60  has a first end  72  secured to the bottom of the guide block  48 . The cable  60  extends downwardly around a pulley  74  mounted at the lower end of the guide track  46  in the sidewall  14 , and then upwardly over the top wall  18 . The second end  76  of the cable  60  is secured to the top of the guide block  49 . The third cable  62  has a first end  78  attached to the guide block  49 . The cable  62  extends downwardly around a pulley  80  rotatably mounted in the guide track  47  in the sidewall  16 , and then upwardly over the top wall  18 . The opposite end  82  of the cable  62  extends around the drum gear  66  in a second groove  84  thereof and is secured to the drum gear  66 . The cables  58 ,  62  extend around the gear drum  66  in opposite directions, such that upon rotation of the drum gear  66 , one cable is wound onto the drum gear  66  and the other cable is unwound from the drum gear  66 .  
         [0028]    The ends of the cables  58 ,  60 ,  62  can be attached in any convenient manner to the drum gear  66  and guide blocks  48 ,  49 . For example, as best seen in FIG. 4, a nodule  86  is provided on the end  64  of the cable  58  and the end  82  of the cable  62  are adapted to be matingly received within cavities or recesses  88  in the drum gear  66 . Similar cavities or recesses are provided in the guide blocks  48 ,  49  to receive the nodule  86  on the cable ends connected to the guide blocks  48 ,  49 .  
         [0029]    The drum gear  66  includes perimeter teeth  90  which mesh with a worm gear  92 . The worm gear is mounted on a shaft  94  for rotation therewith. An actuation handle  96  is mounted on the forward end of the shaft  94  and is positioned adjacent the front opening of the washing chamber  12  for access when the door  24  is opened. Upon manual turning of the handle  96  in the clockwise position, the worm gear  92  rotates in a counterclockwise direction, as seen in FIG. 4, so as to further wrap the cable  58  around the drum gear  66  and to unwrap the cable  62  from the drum gear  66 , thereby raising the guide blocks  48 ,  49  within the guide tracks  46 ,  47  so as to raise the middle rack  34  within the washing chamber  12 . Turn the handle  96  in a counterclockwise direction rotates the drum gear  66  in a clockwise direction, thereby unwrapping the cable  58  from the drum gear  66  and wrapping the cable  62  further around the drum gear  66  so as to pull the guide blocks  48 ,  49  downwardly within the guide tracks  46 ,  47  thereby lowering the middle rack  34  within the washing chamber  12 .  
         [0030]    Preferably, the shaft  94  is square or hex-shaped and slidably extends through the worm gear  92 . Thus, the handle  96  can be moved from a position next to the front opening of the washing chamber  12  such that the door  24  can be closed, and pulled outwardly a short distance away from the front opening of the washing chamber  12  when the door  24  is opened so as to provide easy turning of the handle  96  by a user. The sidewall  14  includes a recess  98  to house the handle  96  when in the retracted or inoperative position, as best seen in FIG. 1.  
         [0031]    The cables  60 ,  62  extend through flexible conduits  100  extending over the top wall  18  of the dishwasher  10 . The conduits  100  terminate at each end in a bushing  102  which is slidably mounted within a channel insert  104  adjacent the top of the guide tracks  46 ,  47 . A spring  106  is provided within the channel insert  104 . As the cables  60 ,  62  are pulled downwardly through the channel insert  104 , the spring  106  compresses to provide feedback to the user as the guide blocks  48 ,  49  reach the end of their travel within the guide tracks  46 ,  47  of, if the dishes start to compress or contact the underside of upper rack  30 . Thus, the user knows when to stop turning the handle  96 .  
         [0032]    In an alternative embodiment, the cable  62  can be eliminated, with the lowering of the rack  32  occurring by gravity when the handle  96  is turned in a counterclockwise direction.  
         [0033]    As a further alternative, a small electric motor (not shown) can be operatively connected to the drum gear  66 , with a control switch provided on the control panel of the dishwasher  10 . Thus, the lift mechanism can be quickly and easily actuated via the switch.  
         [0034]    The invention has been shown and described above with the preferred embodiments, and it is understood that many modifications, substitutions, and additions may be made which are within the intended spirit and scope of the invention. From the foregoing, it can be seen that the present invention accomplishes at least all of its stated objectives.