Abstract:
A roller assembly for an appliance such as e.g., a rack assembly of a dishwashing appliance is provided. The roller assembly is connected to e.g., the rack of the appliance. The roller assembly includes a roller that is carried upon a primary axle into which a secondary axle is received. One or more such rollers can be used with each roller assembly. The construction can provide improved strength over conventional designs such as e.g., where the roller is directly connected to a wire member. Certain embodiments can also provide aesthetic benefits in that the rollers can be partially or completely hidden depending upon the viewing angle.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to roller assembly for an appliance such as e.g., a rack assembly of a dishwashing appliance. 
       BACKGROUND OF THE INVENTION 
       [0002]    A common design for a dishwashing appliance includes one or more dishwashing rack assemblies that are movable in and out of a wash chamber. One or more articles (such as dishes, cooking utensils, cups, glasses, etc.) can be placed on the racks for positioning near spray assemblies in the wash chamber that provide sprays of fluid for washing and rinsing. Using features such as e.g., tines, the racks allow a user to organize the articles while also orienting the articles in a manner intended to facilitate the removal of food soils from the surfaces of the articles. Movement of the rack assembly in and out of the wash chamber allows the user more convenient access for the loading and unloading of articles. 
         [0003]    Both an upper and lower rack assembly may be provided. Commonly, the lower rack assembly may be provided with wheels that are carried directly on wire members attached to, or forming part of, the rack assembly. The wire is intended to serve as an axle about which the wheel rotates. This approach can present several problems. 
         [0004]    For example, the wire member onto which the rack is mounted can be easily damaged. If the wire member is bent, the rack may not move properly in and out of the wash chamber. As such, special handling is required during manufacture. If the problem occurs or is not discovered until after a user has taken delivery, the expense of a service call may be incurred. 
         [0005]    Additionally, depending upon e.g., the amount of weight placed into the rack by the user, the wire member may flex or bend in a manner that adversely affects the ability of the wheel to roll properly. Again, this may prevent the rack from moving properly in and out of the wash chamber. The wheel may not be oriented properly and/or may slide rather than roll—all of which can undesirably require more force to move the rack in and out. 
         [0006]    Furthermore, from an aesthetic perspective, certain consumers may find the appearance of the wheel and its wire axle unattractive and/or non-robust. The wheels are typically visible from the top and sides of the rack. The wire axle, wheel, or both, may appear structurally weak to certain consumers. 
         [0007]    Accordingly, in view of problems including those set forth above, a more robust wheel or roller assembly for an appliance would be useful. More particularly a wheel or roller assembly that is not readily bent and/or does not use a rod or wire member as a wheel axle would be beneficial. Such an assembly that can have improved strength for supporting the weight of a loaded rack assembly would be useful. A wheel or roller assembly that can also provide improved aesthetics would be advantageous. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0008]    The present invention provides a roller assembly for an appliance such as e.g., a rack assembly of a dishwashing appliance. The roller assembly is connected to e.g., the rack of the appliance. The roller assembly includes a roller that is carried upon a primary axle into which a second axle is received. One or more such rollers can be used with each roller assembly. The construction can provide improved strength over conventional designs such as e.g., where the roller is directly connected to a wire member. Other features can also be used to further enhance the strength of the roller assembly. Certain embodiments can also provide aesthetic benefits in that the rollers can be partially or completely hidden depending upon the viewing angle. Additional aspects and advantages of the invention will be set forth in part in the following description, or may be obvious from the description, or may be learned through practice of the invention. 
         [0009]    In one exemplary embodiment of the present invention, a roller assembly for an appliance is provided. The roller assembly includes a carrier with at least one primary axle projecting from the carrier. The primary axle defines a cylindrically-shaped outer surface portion and an opening. A cover is attached to the carrier. At least one secondary axle projects from the cover and is positioned into the opening of the primary axle. A roller defines a radial direction and defines an axial direction about which the roller is rotatable. The roller is received onto the cylindrically-shaped outer surface portion of the primary axle and is rotatable about the primary axle. At least one attachment mechanism is defined by the carrier and the cover and is configured to connect the roller assembly to the appliance. 
         [0010]    In another exemplary embodiment, the present invention provides a dishwasher appliance. The appliance includes a cabinet having a wash chamber. A rack assembly is received into the wash chamber. The rack assembly includes a bottom wall. The rack assembly is constructed from a plurality of elongated members extending along lateral, vertical, and transverse directions and configured for receipt of articles for washing. A plurality of roller assemblies are attached to the bottom wall of the rack assembly. Each roller assembly includes a plurality of primary axles. Each of the primary axles has a cylindrically-shaped outer surface portion and an opening. A plurality of secondary axles are provided with one each received into each one of the openings of the primary axles. A plurality of rollers are carried upon the outer surface portions of the primary axles. 
         [0011]    These and other features, aspects and advantages of the present invention will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]    A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures, in which: 
           [0013]      FIG. 1  provides a front view of an exemplary embodiment of a dishwasher of the present invention. 
           [0014]      FIG. 2  provides a partial, cross-sectional side view of the exemplary embodiment of  FIG. 1 . 
           [0015]      FIG. 3  is a perspective view of an exemplary rack assembly of the present invention including exemplary roller assemblies. 
           [0016]      FIG. 4  is close-up, perspective view of an exemplary embodiment of roller assembly as attached to the exemplary rack assembly in  FIG. 3 . A portion of the attachment mechanism for connecting the roller assembly to the rack has been removed for purposes of illustration. 
           [0017]      FIG. 5  is another close up, perspective view of the exemplary roller assembly of  FIG. 3  as viewed from a different side than shown in  FIG. 4 . 
           [0018]      FIG. 6  is an exploded view of the exemplary roller assembly shown in  FIG. 3 . 
           [0019]      FIG. 7  is a cross-sectional view of an exemplary embodiment of a roller as used in the exemplary roller assembly of  FIG. 3 . 
           [0020]      FIG. 8  is a cross-sectional view of an exemplary embodiment of a roller as used in the roller assembly shown in  FIG. 3 . For this exemplary embodiment, the roller is shown in place on a primary axle into which a secondary axle has been received. 
           [0021]      FIG. 9  is another exploded view of the exemplary roller assembly of  FIG. 3 . 
           [0022]      FIG. 10  is a side view of the exemplary roller assembly of  FIG. 3 . 
           [0023]      FIG. 11  is a perspective view of the bottom of an exemplary cover as used in the exemplary embodiment of a roller assembly shown in  FIG. 3 . 
           [0024]      FIG. 12  is a side view of an exemplary carrier as used in the exemplary embodiment of a roller assembly shown in  FIG. 3 . The side shown receives the exemplary cover shown in  FIG. 11 . 
           [0025]      FIG. 13  is a top view of the exemplary roller assembly of  FIG. 3 . 
           [0026]      FIG. 14  provides an elevation view of an exemplary roller of the present invention as positioned in a guide in e.g., a wash chamber of an appliance. 
       
    
    
       [0027]    In the figures, the same or similar reference numerals indicate the same or similar features. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0028]    Reference now will be made in detail to embodiments of the invention, one or more examples of which are illustrated in the drawings. Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope or spirit of the invention. For instance, features illustrated or described as part of one embodiment can be used with another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents. 
         [0029]      FIGS. 1 and 2  depict an exemplary domestic dishwasher  100  that may be configured in accordance with aspects of the present disclosure. For the particular embodiment of  FIG. 1 , the dishwasher  100  includes a cabinet  102  (or chassis) having a tub  104  therein that defines a wash chamber  106 . The tub  104  includes a front opening (not shown) and a door  120  hinged at its bottom  122  for movement between a normally closed vertical position (shown in  FIGS. 1 and 2 ), wherein the wash chamber  106  is sealed shut for washing operation, and a horizontal open position for loading and unloading of articles from the dishwasher. Latch  114  is used to lock and unlock door  120  for access to chamber  106 . 
         [0030]    Upper guide rails  124  are mounted on opposing tub side walls  128  to support and provide for movement for upper rack  130 . Lower guides  126  are all positioned in opposing manner of the sides of chamber  106  and provide a ridge or shelf for roller assemblies  150  so as to support and provide for movement of lower rack  132 . Each of the upper and lower racks  130 ,  132  is fabricated into lattice structures including a plurality of elongated members  134 . Each rack  130 ,  132  is adapted for movement between an extended loading position (not shown) in which the rack is substantially positioned outside the wash chamber  106 , and a retracted position (shown in  FIGS. 1 and 2 ) in which the rack is located inside the wash chamber  106 . This is facilitated by wheels  136  and rollers  156  of roller assemblies  150 , for example, that carry racks  130  and  132 , respectively. A silverware basket  152  may be removably attached to the lower rack  132  for placement of silverware, small utensils, and the like, that are too small to be accommodated by the upper and lower racks  130 ,  132 . 
         [0031]    The dishwasher  100  further includes a lower spray-arm assembly  144  that is rotatably mounted within a lower region  146  of the wash chamber  106  and above a tub sump portion  142  so as to rotate in relatively close proximity to the lower rack  132 . A mid-level spray-arm assembly  148  is located in an upper region of the wash chamber  106  and may be located in close proximity to upper rack  130 . Additionally, an upper spray or spray arm assembly (not shown) may be located above the upper rack  130 . 
         [0032]    The lower and mid-level spray-arm assemblies  144 ,  148  and the upper spray assembly are fed by a fluid circulation assembly for circulating water and dishwasher fluid in the tub  104 . Portions of the fluid circulation assembly may be located in a machinery compartment  140  located below the bottom sump portion  142  of the tub  104 , as generally recognized in the art. Each spray-arm assembly includes an arrangement of discharge ports or orifices for directing washing liquid onto dishes or other articles located in the upper and lower racks  130 ,  132 , respectively. The arrangement of the discharge ports in at least the lower spray-arm assembly  144  provides a rotational force by virtue of washing fluid flowing through the discharge ports. The resultant rotation of the lower spray-arm assembly  144  provides coverage of dishes and other dishwasher contents with a washing spray. 
         [0033]    The dishwasher  100  is further equipped with a controller  116  to regulate operation of the dishwasher  100 . Controller  116  may include a memory and microprocessor, such as a general or special purpose microprocessor operable to execute programming instructions or micro-control code associated with a cleaning cycle. The memory may represent random access memory such as DRAM, or read only memory such as ROM or FLASH. In one embodiment, the processor executes programming instructions stored in memory. The memory may be a separate component from the processor or may be included onboard within the processor. 
         [0034]    Controller  116  may be positioned in a variety of locations throughout dishwasher  100 . In the illustrated embodiment, controller  116  may be located within a control panel area  110  of door  120  as shown. In such an embodiment, input/output (“I/O”) signals may be routed between the control system and various operational components of dishwasher  100  along wiring harnesses that may be routed through the bottom  122  of door  120 . Typically, the controller  116  includes a user interface panel  112  through which a user may select various operational features and modes and monitor progress of the dishwasher  100 . In one embodiment, the user interface panel  112  may represent a general purpose I/O (“GPIO”) device or functional block. In one embodiment, the user interface panel  112  may include input components, such as one or more of a variety of electrical, mechanical or electro-mechanical input devices including rotary dials, push buttons, and touch pads. The user interface  112  may include a display component, such as a digital or analog display device designed to provide operational feedback to a user. The user interface  112  may be in communication with the controller  116  via one or more signal lines or shared communication busses. 
         [0035]    It should be appreciated that the invention is not limited to any particular style, model, or configuration of dishwasher. The exemplary embodiment depicted in  FIGS. 1 and 2  is for illustrative purposes only. For example, different locations may be provided for a user interface  112 , different configurations may be provided for racks  130 ,  132 , and other differences may be applied as well. 
         [0036]      FIG. 3  provides a perspective view of an exemplary embodiment of a lower rack assembly  132  of the present invention. Rack assembly  132  is constructed from a plurality of elongated members  134 . By way of example, elongated members  134  may be constructed from rods or wires welded together and to which a coating may be applied for protection. The elongated members  134  extend along lateral direction L, transverse direction T, and vertical direction V. The members  134  extending along the lateral and transverse directions create a bottom wall  158  of lower rack assembly  132 . A plurality of tines  154  extend vertically from bottom wall  158  to provide support for various articles that can be placed in rack assembly  132  for cleaning. 
         [0037]    As shown, rack assembly  132  includes a plurality of roller assemblies  150  attached to bottom wall  158 . For this embodiment, four roller assemblies  150  (one is not visible in  FIG. 3 ) are used near each of the four corners of rack assembly  132 . The roller assemblies  150  are each oriented to allow for movement of rack assembly  132  along transverse direction T in and out of wash chamber  106  ( FIG. 2 ). 
         [0038]      FIGS. 4 and 5  provide close up, perspective views of roller assembly  150  attached to rack assembly  132 . In  FIG. 4 , portions of the attachment mechanism (i.e. the tapered fingers  194  and  202  as more fully described later with  FIG. 6 ) are removed to reveal the positioning of lateral extending, elongated wire members  160  into tapered grooves  196  and  204  ( FIG. 6 ) of roller assembly  150 . As will be described more fully, wire members  160  are trapped within grooves  196  and  204  to attach roller assembly  150  to rack assembly  132 . In addition, a pair of support arms  164  longitudinally from roller assembly  150  along the lateral direction L (which is the same as the axial direction defined by the axis of rotation of rollers  156 ). Each support arm  164  includes a support arm hook  168  that is configured for receipt of an elongated member  162  extending along the transverse direction T of the appliance  100 . As such, support arms  164  help attach roller assembly  150  to rack  134  and also help prevent twisting of roller assembly  150  relative to rack  132 . 
         [0039]      FIGS. 6 and 9  provide exploded views of roller assembly  150  while  FIG. 11  provides a perspective view of the a cover  170  of assembly  150 . As shown, roller assembly  150  is constructed from a carrier  172  attached to cover  170  with a pair of rollers  156  positioned therebetween. For this exemplary embodiment, two primary axles  174  project from carrier  172  along lateral direction L, which is parallel to the axial direction or axis of rotation A of rollers  156  ( FIG. 7 ). Two secondary axles project from the cover  170 . Each secondary axle is positioned into an opening  178  formed by a primary axle  174 . Primary axles  174  each define a cylindrically-shaped outer surface portion  176  onto which a respective roller  156  is slidably received. Each roller  156  is rotatable about its primary axle  174 . 
         [0040]    Turning now to the cross-sectional view of  FIGS. 7 and 8 , roller  156  includes a bore  178  into which the primary and secondary axles  174  and  188  are received in a complementary manner. Bore  178  extends along the axial direction A between a first side  179  and a second side  181  of roller  156 . Each axle  174  and  188  can be slightly chamfered along the axial direction A to facilitate manufacturing of assembly  150 . 
         [0041]    Roller  156  includes a cylindrical portion  183  having an exterior surface  185  and an interior surface  187  that defines bore  178 . A first roller contact surface  184  is positioned along first side  179  of roller  156  on an inwardly projecting rim  189  of cylindrical portion  183 . As such, first roller contact surface  184  is positioned radially inward of interior surface  187  so that it is closer to the axis of rotation (located at arrows A-A) of roller  156 . A second roller contact surface  186  is positioned at the second side  181  of roller  156 . Second roller contact surface  186  has a frustoconical shape that faces outwardly from bore  178  along axial direction A. 
         [0042]    As shown in  FIG. 8 , first roller contact surface  184  is in sliding contact with the cylindrically-shaped outer surface portion  176  of primary axle  174 . Second roller contact surface  186  is in slidable contact with an arcuate-shaped outer surface portion  180  of primary axle  174 . As shown, the arcuate-shaped outer surface portion  180  is positioned between carrier  172  and primary axle  174 . By controlling the size and location of contact surfaces  184  and  186 , the friction associate with the rotation of roller  156  about primary axle  174  can be controlled as to improve the ease with which rack assembly  132  is moved in and out of chamber  106 . 
         [0043]    Each roller  156  also includes a flange portion  182  that extends along circumferential direction C and projects outwardly along radial direction R. Flange portion  182  provides a third roller contact surface  191  that can be used to help secure the movement of rack assembly  132  in and out of wash chamber  106 . For example, referring to  FIG. 14 , guides  126  can be positioned in an opposing manner on each side of chamber  106  adjacent to the lateral sides  131  and  133  ( FIG. 3 ) of rack assembly  132 . As shown for side  133  in  FIG. 14 , rollers  156  is received onto a guide  126  and rolls along lateral direction T ( FIG. 3 ) to move in and out of chamber  106 . 
         [0044]    Loading of rack assembly  132  creates a torsional force F that pushes roller contact surface  191  towards guide  126 . However, because the position of guide  126  is fixed, force F is resisted and undesirable rotation of roller  156  is prevented. Thus, flange portion  182  with third roller contact surface  191  can thereby improve the structural integrity or stiffness of rack assembly  132  while also ensuring the rollers  156  remain properly oriented during movement along transverse direction T. Door  120  can also be provided with a guide similar to guide  126  on both lateral sides  131  and  133  so that rack assembly  132  can be guided onto door  120  when pulled out of wash chamber  106 . 
         [0045]    As shown in the top view provided by  FIG. 13 , roller assembly  150  includes attachment mechanisms  216  and  218  for attachment to rack assembly  132 . Referring now to  FIG. 6  and  FIGS. 9-12 , attachment mechanism  216  is constructed from a first tapered finger  194  that is received in a complementary manner into a first tapered groove  196 . First tapered finger  194  projects from carrier  172  while first tapered groove  196  is defined by cover  170 . Additionally, first tapered finger  194  forms an L-shape ( FIG. 12 ). Together, as best seen in  FIG. 10 , first tapered finger  194  and groove  196  extend along axial direction A to define a first channel  198  that receives and traps an elongated member  160  of rack assembly  132  ( FIG. 4 ). 
         [0046]    Continuing with  FIG. 6  and  FIGS. 9-12 , attachment mechanism  218  is constructed from a second tapered finger  202  that is received in a complementary manner into a second tapered groove  204 . Second tapered finger  202  projects from carrier  172  while second tapered groove  204  is defined by cover  170 . Additionally, second tapered finger  202  forms an L-shape ( FIG. 12 ). Together, as best seen in  FIG. 10 , second tapered finger  202  and second tapered groove  204  extend along axial direction A to define a second channel  200  that also receives and traps another elongated member  160  of rack assembly  132  ( FIG. 4 ). 
         [0047]    As shown, second channel  200  is wider along transverse direction T than first channel  198 . This difference in width allows roller assembly  150  to readily accommodate rack assemblies having different spacings along transverse direction T between the elongated members  160 . 
         [0048]    Roller assembly  150  is also provided with several features for the secure attachment of cover  170  to carrier  172 . As shown in  FIGS. 9-12 , a pair of attachment arms  190  extend from cover  170  along lateral direction L and into a slot  166  defined by carrier  172 . Each attachment arm  190  includes a prong  192  for securing arm  190  to carrier  172 . 
         [0049]    Additionally, referring to  FIGS. 10 through 13 , multiple receivers  206  project from cover  170  along lateral direction L and each having a receiver opening  208 . Multiple detents  210  project along vertical direction V from carrier  172  and are ramped along axial direction A ( FIGS. 6 and 9 ). Detents  210  are positioned on carrier  172  to align with receivers  206  on cover  170 . 
         [0050]    Accordingly, as tapered fingers  194  and  202  are moved along lateral direction L into tapered channels  198  and  200  during construction of roller assembly  150 , receivers  206  eventually contact a respective detent  210 . Receivers  206  are deflected along vertical direction V as they slid along the ramped detents  210 . Eventually, receivers  206  slide completely over detents  210  along lateral direction L and snap into place. 
         [0051]    A variety of materials can be used for the construction of roller assembly  150 . For the exemplary embodiment shown in the figures, cover  170  is constructed from a first plastic material while carrier  172  is constructed from a second plastic material that is less flexible than the first plastic material. For example, carrier  172  can be constructed from a chemically coupled homopolymer-polypropylene, containing 30% strand glass fibers and a stabilizer to reduce long-term heat aging, which particularly enhances performance in a dishwasher environment. Cover  170  can be constructed from a non-glass reinforced polymer. As such, cover  170  can have more flexibility to facilitate e.g., the flexing of receivers  206  during construction as discussed above. By way of example, rollers  156  can be constructed from an acetal copolymer, consisting of oxymethylene and oxyethylene. Such a composition can be inherently more stable and resistant to thermal degradation during service life because the repeating copolymer units block polymer “unzipping” under thermal stress. In addition to thermal stability, the copolymer also provides enhanced property retention when exposed to higher levels of pH in alkaline detergent solutions. 
         [0052]    Although each roller assembly  150  is shown with two rollers  156 , using the teachings disclosed herein it will be understood that carriers with one, two or more rollers  156  may also be constructed in other exemplary embodiments of the present invention as well. Additionally, covers  170  and carrier  172  can have other shapes to provide different aesthetic effects. 
         [0053]    Roller assembly  150  is also equipped with tabs  212  and  214  as shown in  FIGS. 6 ,  9 ,  10 ,  11 , and  13  that extend along vertical direction V. Tabs  212  and  214  may be used to support articles placed in rack assembly  132 . For example, tabs  212  and  214  can hold the edge of a plate or baking sheet so as to properly orient the plate in rack assembly  132 . Tabs  212  and  214  enable increased rack capacity without reducing wash performance. Additionally, tabs  212  and  214  still allow a silverware basket to be located above them in rack  132 . 
         [0054]    This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.