Patent Publication Number: US-6662814-B2

Title: Mid-level spray-arm assembly

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to spray-arms, and, more particularly, to spray-arm assemblies for dishwashers. 
     One type of domestic dishwasher includes a lower spray-arm mounted in a lower region of a wash chamber, and a mid-level spray-arm mounted above the lower spray-arm. See, for example, U.S. Pat. No. 3,969,137. Typically, the lower spray-arm sprays water upward over dishware and items to be cleaned in a lower rack, and the mid-level spray-arm sprays water upward over dishware and items to be cleaned in an upper rack. A pump injects water into the lower spray-arm for rotary motion thereof, and further directs a stream of water through the lower spray-arm for θ receipt by the mid-level spray-arm and for imparting rotary motion to the mid-level spray-arm. The mid-level spray-arm is mounted to the upper rack, and a sealed retractable tower coupled to the lower spray-arm delivers water from the lower spray-arm to the mid-level spray-arm when water pressure reaches pre-determined levels. The mid-level spray-arm rotates or spins relative to the upper rack upon a bearing surface. 
     The bearing surface of the mid-level spray-arm, however, tends to wear unevenly. Uneven wear of the bearing surface can lead to impaired performance of the spray-arm and premature jamming and failure of the bearing surface which may prevent the mid-level spray-arm from rotating. In addition, sealing the connection of the retractable tower to the upper and lower racks adds to the cost and complexity of the spray-arms, and consequently increases manufacturing and assembly costs. Still further, known mid-level spray-arms tend to generate considerable noise from spray-arm water jets that impact side walls of the washing chamber. 
     Accordingly, it would be desirable to provide a mid-level spray-arm assembly that promotes more even wear of the bearing surface, thereby extending the bearing life of the spray-arm. It would also be desirable to provide a mid-level spray-arm bearing that reduces instances of jamming. Further, it would be desirable to eliminate sealed spray-arm connections to reduce manufacturing costs of dishwashers. Also, it would be desirable to provide a quieter operating spray-arm. 
     BRIEF SUMMARY OF THE INVENTION 
     In an exemplary embodiment of the invention, a dishwasher mid-level spray-arm assembly includes a spray-arm, a bracket for supporting the spray-arm on an upper rack of the dishwasher, and a bearing for coupling the bracket and spray-arm and that forms a first bearing surface for rotation of the bearing coupling relative to the bracket and a second bearing surface for rotation of the spray-arm relative to the bearing coupling. The first and second bearing surfaces promote a more even wear of the bearing surface, and further allow rotation of the spray-arm even when one of the bearing surfaces fails or jams. 
     More specifically, the spray-arm includes a hub having an outer surface and a hub slot. The bracket includes an inner surface and a bracket slot, and the bearing coupling is retained partially in the hub slot and partially in the bearing slot. The coupling is an annular disk clip partially retained in the hub slot and partially retained in the bracket slot. A small gap separates the bracket inner surface from the hub outer surface to substantially eliminate frictional engagement of the bracket inner surface and the hub outer surface, and relative rotational movement of the bearing coupling and bracket, and also relative rotation of the spray-arm hub and the bearing coupling is accomplished on smooth first and second bearing surfaces. 
     The spray-arm hub includes a funnel that accommodates an off-centering or misalignment of the spray-arm with respect to a retractable tower that supplies water to the mid-level spray-arm, and also includes angled fluid discharge ports arranged so that spray-arm water jets do not impact side walls of a dishwasher wash chamber during washing operation. Specifically, a spray pattern of the mid-level spray-arm is substantially confined within a lower outer perimeter of the upper rack of the dishwasher, and items placed at the lower outer perimeter intercept the outer perimeter of the spray pattern and prevent water from impacting the side walls of the wash chamber. Noise from excitation of the wash chamber side walls is considerably reduced and a noticeably quieter operating dishwasher is realized. 
     The spray-arm assembly is easily assembled with snap-fit engagement of the bearing coupling to the bracket, and snap-fit engagement of the bracket and coupling to the spray-arm hub. Thus, a long life, easily assembled spray-arm assembly is provided. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side elevational view of a dishwasher partially broken away and including a mid-level spray-arm assembly; 
     FIG. 2 is a perspective view of the mid-level spray-arm assembly shown in FIG. 1; 
     FIG. 3 is a top plan view of the mid-level spray-arm assembly shown in FIG. 2; 
     FIG. 4 is a cross sectional view of the mid-level spray-arm assembly along line  4 — 4  of FIG. 3; 
     FIG. 5 is an enlarged view of a portion of FIG. 4; 
     FIG. 6 is a partial cross sectional view of the dishwasher shown in FIG. 1 along line  6 — 6 ; 
     FIG. 7 is a partially broken away view of a portion of the dishwasher of FIG. 1; and 
     FIG. 8 is a side elevational view of a second embodiment of a dishwasher partially broken away and including a mid-level spray-arm assembly. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     FIG. 1 is a side elevational view of an exemplary conventional domestic dishwasher  10  partially broken away, the construction and operation of which is well known in the art, and in which the present invention may be practiced. It is contemplated, however, that the invention may be practiced in other types of dishwashers beyond the dishwasher  10  described and illustrated herein. Accordingly, the following description is for illustrative purposes only, and the invention is in no way limited to use in a particular type dishwasher, such as dishwasher  10 . 
     Dishwasher  10  includes a cabinet  12  having a tub  14  therein and forming a wash chamber  16 . Tub  14  includes a front opening (not shown in FIG. 1) and a door  20  hinged at its bottom for movement between a normally closed vertical position (shown in FIG. 1) and a horizontal open position (not shown). Upper and lower guide rails  24 ,  26  are mounted on tub side walls  28  and accommodate upper and lower roller-equipped racks  30 ,  32 , respectively. Each of upper and lower racks  30 ,  32  is fabricated from known materials into lattice structures including a plurality of elongate members  34 , and each rack  30 ,  32  is adapted for movement between an extended loading position (not shown) in which the rack is substantially positioned outside wash chamber  16 , and a retracted position (shown in FIG. 1) in which the rack is located inside wash chamber  16 . Conventionally, a silverware basket (not shown in FIG. 1) is removably attached to lower rack  32  for placement of silverware, utensils, and the like that are too small to be accommodated by upper and lower racks  30 ,  32 . 
     A control input selector  36  is mounted at a convenient location on an outer face  38  of door  20  and is coupled to known control circuitry (not shown) and control mechanisms (not shown) for operating dishwasher system components located in a machinery compartment  40  below a bottom  42  of tub  14 . An electric motor  44  drivingly coupled to a pump  46  provides for circulation of water from a sump portion  48  of tub  14  to a water discharge pipe  50 . An inlet pipe  52  connects sump  48  to an inlet (not shown) of pump  46 , and pump  46  includes a discharge conduit (not shown) that communicates in flow relationship with a building plumbing system (not shown). 
     A lower spray-arm-assembly  54  is rotatably mounted within a lower region  56  of wash chamber  16  and above tub bottom  42  so as to rotate in relatively close proximity to lower rack  32 . A mid-level spray-arm assembly  58  is located in an upper region  60  of wash chamber  16  and is rotatably attached to upper rack  30  in close proximity thereto and at a sufficient height above lower rack  32  to be above a largest item, such as a dish or platter (not shown), that is expected to be washed in dishwasher  10 . Mid-level spray-arm assembly  58  includes a central hub  62  and a downwardly projecting funnel  64  for receiving a water stream through a retractable tower  66  of lower spray-arm assembly  54  without retractable tower  66  sealingly engaging mid-level spray-arm assembly  58 . Mid-level spray-arm funnel  64  facilitates a degree of off-centering or misalignment of mid-level spray-arm  58  with respect to retractable tower  66  as water from retractable tower  66  impacts funnel  64 . Thus, precise positioning of mid-level spray-arm  58  vis-a-vis retractable tower  66  is avoided. Retractable tower  66  is mounted to lower-spray-arm assembly  54  and therefore rotates with lower spray-arm assembly  54  as dishwasher  10  is used, thereby eliminating sealing problems in connections between retractable tower  66  and lower spray-arm assembly  54 . 
     Both lower and mid-level spray-arm assemblies  54 ,  58  include an arrangement of discharge ports or orifices for directing washing liquid upwardly onto dishes located in upper and lower racks, respectively. The arrangement of the discharge ports provides a rotational force by virtue of washing fluid action through the discharge ports. The resultant rotation of the spray-arm provides coverage of dishes and other dishwasher contents with a washing spray. 
     FIG. 2 is a perspective view of mid-level spray-arm assembly  58  including a bracket  80  attached to central hub  62  (not shown in FIG. 2) of spray-arm  82 . Bracket  80  includes four attachment members  84  depending from a shroud  86  inserted over spray-arm hub  62  for receiving elongate members  34  (shown in FIG. 1) of upper rack  30  (shown in FIG.  1 ). Thus, bracket  80  may be removably attached to upper rack  30  by inserting rack elongate members  34  within bracket attachment members  84  to support spray-arm  82  below lower rack  32 . Spray-arm  82  includes opposite ends  88  and a contoured surface  90  defined by ends  88  and opposite side edges  92 . Discharge ports or orifices  94  are asymmetrically located on contoured surface  90  generate a torque about spray-arm hub  62  when washing fluid is sprayed through discharge ports  94 , causing spray-arm  82  to rotate within bracket  80 , as further described below. 
     FIG. 3 is a top plan view of mid-level spray-arm assembly  58  including a longitudinal axis  110  and a lateral axis  112 . Contoured surface  96  is inversely bilaterally symmetrical about both axes  110 ,  112 , i.e., contoured surface  90  is a reverse mirror image about axes  110 ,  112 . Each side edge  92  is partly curved toward and partly curved away from longitudinal axis  110  between opposite rounded ends  88 . Discharge ports  94  are substantially aligned along longitudinal axis  110  at varying distances from a center  114  of spray-arm  114 . In one embodiment, four discharge ports  94  are located on a first side  116  of spray-arm  82 , and three discharge ports  94  are located on a second side  118  of spray-arm  82 . Bracket  80  includes opposite longitudinal side edges  120  substantially straight and parallel to longitudinal axis  110 , and opposite lateral side edges  122  connecting longitudinal side edges  120 . Bracket lateral side edges  122  include rounded cutouts  124  approximately centered between bracket longitudinal side edges  120  to provide clearance for discharge ports  94  located adjacent or beneath bracket  80  when bracket  80  is attached to spray-arm  82 . 
     FIG. 4 is a cross sectional view of mid-level spray-arm assembly  58  including funnel  64  depending below spray-arm  82  and substantially aligned with spray-arm hub  62 . Funnel  64  includes a conical shaped opening  126  to direct water from lower spray-arm retractable tower  66  (shown in FIG. 1) toward a central passageway  128  extending through spray-arm  82 , and further to channel-water to central passageway  128  when retractable tower  66  is misaligned with a vertical axis  130  of spray-arm  82 . When a fluid flow rate and pressure entering funnel opening  126  reach sufficient levels, spray-arm central passageway  128  fills with washing fluid and jets of washing fluid are sprayed through discharge parts  94 . Due to the placement of discharge ports  94  in spray-arm  82 , fluid action through discharge ports  94  rotates spray-arm  82  about vertical axis  130 . Rotation of spray-arm  82  creates a swirling spray pattern over wash items placed on upper rack  30  (shown in FIG.  1 ). 
     FIG. 5 is an enlarged view of spray-arm central hub  62  and attachment of bracket  80  thereto. Hub  62  includes a generally cylindrical outer surface  140  and a slot  142  therein. Bracket  80  includes a shroud  144  enveloping hub outer surface  140  and including an inner surface  146  and a slot  148  therein that is substantially aligned with hub slot  142 . A bearing coupling  150  extends between hub outer surface  140  and bracket inner surface  146  and is partially retained in the respective slots  142 ,  148  of hub outer surface  140  and bracket inner surface  146 . In one embodiment, bearing coupling  150  is a substantially flat annular disk clip that is snap-fit over hub outer surface  140 . Bearing coupling  150  is fabricated, in one embodiment, from plastic, but in alternative embodiments is fabricated from other suitable materials known in the art. 
     Bearing coupling  150  is dimensioned so that it is slightly smaller than a combined area of respective slots  142 ,  148  of hub outer surface  140  and bracket inner surface  146 . That is, bearing coupling  150  is loosely fitted with respect to both spray-arm hub  62  and bracket  80  to allow relative rotational movement of bearing coupling  150  with respect to both spray-arm hub  62  or bracket  80 , but yet forms an adequate connection between bracket  80  and hub  62  to prevent separation of spray-arm hub  62  and bracket  80  in use. Hub outer surface  140  and bracket inner surface  142  are separated by a small gap  152  to substantially avoid friction between hub outer surface  140  and bracket inner surface  146 . 
     Bearing coupling  150  forms a first bearing surface  154  that allows relative movement of spray-arm hub  62  with respect to bearing coupling  150 , and a second bearing surface  156  that allows relative movement of bearing coupling  150  with respect to bracket  80  when bracket attachment members  84  (shown in FIG. 2) are hung on upper rack elongate members  34  (shown in FIG.  1 ). First and second bearing surfaces  154 ,  156  allow rotation of bearing coupling  150  with respect to both spray-arm hub  62  and bracket  80  promote a more even wear of bearing surfaces  154 ,  156  relative to conventional single-bearing surface spray-arms. Thus, an operating life of mid-level spray-arm assembly  58  is extended relative to known spray-arm systems. Further, first and second bearing surfaces  154 ,  156  allow for rotation of spray-arm  82  relative to bracket  80  even when one of bearing surfaces  154 ,  156  jams or fails. By providing a redundant bearing surfaces  154 ,  156 , spray-arm  82  is prevented from rotating or turning only when both bearing surfaces  154 ,  156  jam or fail concurrently, thereby considerably reducing instances of spray-arm lock. 
     Lower extensions  158  of bracket  80  extend below bracket slot  148  to substantially prevent water and wash fluid from splashing onto bearing surfaces  154 ,  156  and therefore effectively water seal bearing coupling  150 . 
     Mid-level spray-arm assembly  54  is easily assembled by inserting bearing coupling  150  into bracket inner surface slot  148 , and inserting bracket  80  and bearing coupling  150  over spray-arm hub  62  until bearing coupling  150  snaps into hub outer surface slot  142 . Spray-arm  82  is then snapped onto upper rack  30  (shown in FIG. 1) by inserting bracket attachment members  84  (shown in FIG. 2) over elongate rack members  34 . 
     FIG. 6 is a partial cross sectional view of dishwasher  10  illustrating a noise reducing feature of mid-level spray-arm assembly  58 . Upper rack  30  is situated between side walls  160  of wash chamber  16  and mid-level spray-arm assembly  58  is mounted to rack elongate members  34  so that mid-level spray-arm  82  is suspended beneath upper rack.  30 . When door  20  is closed and dishwasher  10  is operated, retractable tower  66  (shown in FIG. 1) feeds water to mid-level-spray-arm  82  and causes spray-arm  82  to rotate about vertical axis  130  (shown in FIG.  4 ). As mid-level spray-arm  82  rotates, jets of water are sprayed through spray-arm fluid discharge ports  94  to form a swirling spray pattern having a substantially circular outer perimeter  162  (shown in phantom in FIG. 6) that is as large as possible without exceeding or crossing a lower outer perimeter  164  of upper rack  30 . When upper rack  30  is properly loaded, such as with glasses  166 , water jets sprayed from mid-level spray-arm  82  are intercepted and prevented from impacting wash chamber side walls  160 . 
     FIG. 7 is a partially broken away view of a portion of dishwasher  10  illustrating midlevel spray-arm  82  extending below upper rack  30  within wash chamber  16 . An outermost fluid discharge port  94  of mid-level spray-arm  82  is constructed to include first and second angles α and θ with respect to spray-arm longitudinal axis  110  so that a water jet (not shown) sprayed through discharge port  94  is intercepted by the contents of upper rack  30 , such as by glass  166 . Therefore, when upper rack  30  is properly loaded with items appropriately placed around upper rack outer perimeter  164 , the items are cleaned with water jets from mid-level spray-arm  82 , while wash tube side walls  160  are substantially free from water jet impact that excites wash tub side walls  160 , thereby eliminating an appreciable component of noise generated by dishwasher  10  in use. 
     In one embodiment, angle θ is approximately 40°, and angle α is approximately 70′ to provide an adequately broad spray jet while minimizing noise from excitation of wash tub side walls  160 . It is contemplated that other values of α and θ may be selected in alternative embodiments to satisfy particular operational conditions of specific dishwasher systems, including but not limited water pressure, the relative sizes of upper rack  30  and mid-level spray-arm  82 , and a vertical distance D 1  that separates upper rack  30  and mid-level spray-arm  82 . 
     FIG. 8 is a side elevational view of a second embodiment of a dishwasher similar to dishwasher  10  (shown in FIGS. 1,  6  and  7 ) but including a known third level, or upper level washing element  172  that receives water from mid-level spray-arm assembly  58  and sprays fluid downward over upper rack  30  for added cleaning effectiveness. A variety of third level washing elements are known in the art, and the present invention is not restricted to practice with a particular third level washing element. 
     Thus, an easily assembled, longer life mid-level spray-arm assembly is provided that extends bearing life relative to known spray-arms, and reduces instances of jammed or inoperable spray-arms due to failed bearing surfaces. The mid-level spray-arm assembly also facilitates quieter operating dishwashers that foster a more pleasant operating environment in the home. 
     While the invention has been described in terms of various specific embodiments, those skilled in the art will recognize that the invention can be practiced with modification within the spirit and scope of the claims.