Abstract:
A wobble joint for use in automatic washing appliances and the like includes inner, outer and intermediate joint members which have nesting curved sliding surfaces that enable the joint members to pivot relative to one another. The joint has motion limiting features acting between the intermediate joint member and each of the inner and outer joint members to restrict relative movement between the outer joint member and the intermediate joint member to pivotal movement within a first plane and to restrict relative movement of the intermediate member and inner joint member to pivotal movement within a second plane transverse to the first plane. The motion limiting features comprise first and second arcuate grooves extending parallel to the first and second planes and retainers captured in the grooves and relatively moveable therealong.

Description:
The disclosure incorporates the wobble joint disclosed in provisional patent application 60/325,626, filed Sep. 28, 2001, whose priority is claimed for this application. 
    
    
     TECHNICAL FIELD 
     This invention relates generally to mechanical joints, and particularly wobble joints wherein one joint member is able to wobble or gyrate about an axis of another joint member through restricted motion of the connection of the joint members. 
     BACKGROUND OF THE INVENTION 
     U.S. Pat. No. 6,115,863 discloses an automatic washing appliance in which a wash plate is supported for wobbling movement within a wash basket for laundering cloths. FIG. 4 of this patent discloses a wobble joint which supports the wash plate for wobbling action during operation of the appliance. The joint is made up in total of at least 11 separate parts which, when assembled, operate to support the outer joint member for relative wobbling movement relative to the inner joint member. 
     It is an object of the present invention to simplify the manufacture and improve upon the performance of such wobble joints for use in washing appliances and other applications. 
     SUMMARY OF THE INVENTION 
     A wobble joint constructed according to a presently preferred embodiment of the invention comprises an outer joint member having a curved sliding surface, an inner joint member having a curved sliding surface, and an intermediate joint member disposed between the inner and outer joint members and having an outer curved sliding surface supporting the curved sliding surface of the outer joint member for relative pivotal movement of the outer and intermediate joint members, and an inner curved sliding surface supporting the curved sliding surface of the inner joint member for relative pivotal movement of the inner and intermediate joint members. The joint further includes mutually engaging motion limiting features acting between the intermediate joint member and each of the inner and outer joint members and restricting the relative pivotal movement of the outer and intermediate joint members to pivotal movement in a first plane containing an axis of either the outer or inner joint member which is supported against pivotal movement, and restricting the relative pivotal movement between the intermediate and inner joint members to pivotal movement within a second plane containing the axis and disposed transverse to the first plane. According to the invention, the motion limiting features include first and second arcuate grooves extending parallel to the first and second planes in combination with retainers captured within the grooves and relatively moveable there along to provide the restricted pivoting movement of the joint members. 
     The invention further contemplates an automatic washing appliance embodying the above-described wobble joint in which a wobble wash plate disposed within a wash basket is supported by the outer joint member for relative wobbling movement about the first joint member during operation of the appliance. The invention has the advantage of simplifying the construction of wobble joints by minimizing the required number of component parts required to support the joint members for relative wobbling movement. 
     The invention has the further advantage of reducing the cost and simplifying the manufacture of such wobble joints through the formation of curved sliding surfaces and mutually engaging groove and retainer features which eliminate the need to utilize separate pins and bearings to support the joint members as in the prior art described above. 
     The invention has the further advantage of providing a wobble joint that is more compact in size by eliminating the need to provide a gap or clearance between the joint members that is employed with the prior art joint. The nesting curved sliding surfaces of the joint members places the joint members in contact with one another and thus enables the joint to be made more compactly and with tighter tolerance than that of the known prior art wobble joints. 
     Another advantage of the present invention is that the tighter tolerance and sliding contact of the joint members reduces lash and thus noise associated with operation of the joint. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will not be described, by way of example, with reference to the accompanying drawings, in which: 
     FIG. 1 is an exploded perspective view of a wobble joint constructed according to a first presently preferred embodiment of the invention; 
     FIG. 2 is a fragmentary cross-sectional view taken generally along lines  2 — 2  of FIG. 1 with the intermediate joint shifted in the direction of arrow B relative to the inner joint; 
     FIG. 3 is a view like FIG. 2 but showing the outer joint shifted in the direction of arrow C relative to the intermediate joint; 
     FIG. 4 is an exploded perspective view of a wobble joint constructed according to a second embodiment of the invention; 
     FIGS. 5 and 6 are enlarged fragmentary sectional views of the joint in FIG. 4 shown in two positions of relative movement of the joint members; 
     FIG. 7 is an enlarged plan view, shown partially broken away, of the intermediate joint member; 
     FIG. 8 is a cross-sectional view taken generally along lines  8 — 8  of FIG. 7; 
     FIG. 9 is a plan view of the outer joint member shown partially broken away; 
     FIG. 10 is a cross-sectional view taken generally along lines  10 — 10  of FIG. 9; and 
     FIG. 11 is a schematic elevation view, shown partially broken away and in section, of an automatic washing appliance incorporating the wobble joint of FIGS. 4-10. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     A wobble joint constructed according to a first embodiment of the invention is shown generally at  10  in FIGS. 1-3 and comprises an inner joint or race  12 , an outer joint or race  14  and an intermediate joint or race  16  disposed about a common axis A. 
     The inner race  12  has a curved and preferably part-spherical surface  18  that nests with an associated curved and preferably part-spherical surface  20  of the intermediate race. The outer race  14  has a part spherical surface  22  that nests with an associated part spherical surface  24  of the intermediate race. The nesting surfaces  18 ,  20  and  22 ,  24  support the races  12 ,  14  and  16  for relative sliding pivotal movement about respective centers of curvature  26 ,  28  of the spherical surfaces  18 ,  20  and  22 ,  24 . The centers of curvature  26 ,  28  are preferably the same. 
     The inner race  12  and intermediate race  16  have mutually engaging motion-limiting features  30 ,  32 , respectively, which limit the sliding pivotal movement of the intermediate race  16  relative to the inner race  12  to one degree of freedom of motion in the direction of arrow B in a plane P 1  passing through the axis A. The outer race  14  and intermediate race  16  have mutually engaging motion-limiting features  34 ,  36 , respectively. The features  34 ,  36  limit the sliding pivotal movement of the outer race  14  relative to the intermediate race  16  to one degree of movement in the direction of arrow C in a plane P 2  passing through the axis A which is transverse to the plane P 1  and preferably perpendicular thereto. With the inner race  12  held stationary, the outer race  14  is able to radially gyrate or “wobble” relative to the inner race  12  while being secured against rotation relative to the inner race  12  about the axis A. 
     The races  12 ,  14 ,  16  are preferably formed with openings or bores  38 ,  40 ,  42 , respectively, that are in registry along the axis A for receiving a shaft (not shown). The opening  40  of the outer race  14  may be relatively larger in diameter than that of the openings  38 ,  42  of the inner and intermediate races  12 ,  16  to accommodate the sliding pivotal, wobbling movement of the outer race  14  without interference from the shaft (not shown). 
     The races  12 ,  14 ,  16 , according to the first embodiment, are preferably stacked upon one another in the axial direction. The intermediate race  16  is stacked upon and overlies the inner race  12  and the outer race  14  is stacked upon and overlies the intermediate race  16  along the axis A. The outer race  14  has a cup-shaped concave inner surface that defines its part-spherical surface  22 . The surface  22  mates with and is supported by an outer convex dome-shaped surface of the intermediate race  16  that defines its associated part-spherical surface  24 . The intermediate race  16  has a cup-shaped concave inner surface that defines its other part-spherical surface  20 . The surface  20  mates with and is supported by an outer convex dome-shaped surface of the inner race  12  that defines its associated part-spherical surface  18 . 
     The motion limiting features  30 ,  32  of the inner race  12  and intermediate race  16  preferably comprise nesting ribs and grooves (or vise versa) that extend in the plane P 1 . The motion limiting features  34 ,  36  of the outer race  14  and intermediate race  16  preferably comprise nesting ribs and grooves (or vise versa) that extend in the plane P 2 . The motion limiting features may be machined or formed in the races. The motion limiting features are preferably arcuate and may have the same center of curvature as that of the part-spherical surfaces of the races. Of course, features other than nesting ribs and grooves that achieve the same purpose of providing restricted sliding pivotal movement of the races to attain non-rotative wobble movement of the outer race  14  relative to the inner race  12  is contemplated by this invention and are incorporated herein. 
     The inner race  12  and/or the outer race  14  may comprise integral parts of other components of a device. For example, the inner race  12  may form part of a stationary base or hub of the device and the outer race  14  may comprise a plate or other component supported for relative wobbling movement relative to the base or hub. 
     FIGS. 4-11 show a wobble joint  50  constructed according to a second embodiment of the invention. The wobble joint  50  includes an inner race  52 , an outer race  54 , and an intermediate race  56  having a common axis A′. 
     The inner race  52  has a part-spherical surface  58  that nests with a part-spherical surface  60  of the intermediate race  56 . The outer race  54  has a part spherical surface  62  that nests with an associated part-spherical surface  64  of the intermediate race  56 . The nesting surfaces  58 ,  60  and  62 ,  64  support the races  52 ,  54 ,  56  for relative sliding pivotal movement about respective centers of curvature  66 ,  68  of the mating surfaces  58 ,  60  and  62 ,  64 . The centers of curvature  66 ,  68  are preferably the same. 
     The inner race  52  and intermediate race  56  have mutually engaging motion-limiting features  70 ,  72 , respectively, that limit the sliding pivotal movement of the intermediate race  56  relative to the inner race  52  to one degree of freedom of motion in the direction of arrow D in a plane P 3  containing the axis A′. The outer race  54  and intermediate race  56  have mutually engaging motion-limiting features  74 ,  76 , respectively. The features  74 ,  76  limit the sliding movement of the outer race  54  relative to the intermediate race  56  to one degree of freedom of motion in the direction of arrow E in a plane P 4  containing the axis A′ and which is transverse and preferably perpendicular to the plane P 3 . With the inner race  52  held stationary, such as mounted on a hub  77  by a retainer  79  as shown in FIGS. 5 and 6, the outer race  54  is able to radially gyrate or wobble relative to the inner race  52  while being supported against rotation about the axis A′. The outer race  54  may include mounting holes  73  or other mounting structure for mounting an object to be wobbled, such as a wash plate  75  of a washing machine. 
     The motion limiting features  70 ,  72  of the inner race  52  and intermediate race  56  preferably comprise nesting ribs and grooves (or vise versa) that extend in the plane P 3 . The motion limiting features  74 ,  76  of the outer race  54  and intermediate race  56  preferably comprise nesting ribs and grooves (or vise versa) that extend in the plane P 4 . The motion limiting features may be machined or formed in the races. The motion limiting features are preferably arcuate and may have the same center of curvature as that of the part-spherical surfaces of the races. Of course, features other than nesting ribs and grooves that achieve the same purpose of providing restricted sliding pivotal movement of the races to attain non-rotative wobble movement of the outer race  54  relative to the inner race  52  is contemplated by this invention and are incorporated herein 
     As shown best in FIGS. 5-10, the races  52 ,  54 ,  56  are concentrically arranged rather than being axially stacked as with the first embodiment of FIGS. 1-3. The mating part-spherical surfaces are radially arranged. This has the advantage of providing a low axial profile package. Another advantage this second embodiment offers is that the races can be interlocked in a self-contained sub-assembly as shown in FIGS. 5 and 6. The mating surfaces are preferably provided with sufficient clearance to enable the races to be separately formed and then assembled with one another in the manner shown. To ease assembly, the mating surfaces and features may be formed with suitable relief regions to enable the intermediate race  56  to be installed about the inner race  52 , and the outer race  54  about the intermediate race  56  as shown without impairing the operation of the joint  50 . As shown best in FIG. 7, a slot or notch  78  may be formed in the intermediate race  56  of sufficient width and diametrical spacing to receive the inner race  52  end-wise into the intermediate race  56  such that their axes are initially perpendicular, after which the inner race  52  is rotated about 90 degrees to align their axes and fully engage and nest their part-spherical surfaces  70 ,  72 . As shown best in FIG. 9, the outer race  54  is formed with a similar slot or notch  80  of sufficient width and diametrical spacing to receive the pre-assembled inner race  52  and intermediate race  56  end-wise into the outer race  54 , after which the intermediate race  56  is rotated about 90 degrees to align their axes and fully engage and nest their part-spherical surfaces  74 ,  76 . Once assembled, the mating spherical forms of the races serve to interlock the races into a self-contained module. As an alternative or in addition to the notches  80 , one or both of the mating spherical surfaces  70 ,  72  could be formed with a relief area(s) such as a flat to facilitate assembly. 
     FIG. 11 shows the wobble joint  50  incorporated as a component of a vertical axis washing machine assembly or appliance  82 , of the type disclosed in U.S. Pat. No. 6,115,863 (the &#39;863 patent), the disclosure of which is incorporated herein by reference. The wobble joint  50  takes the place of the U-joint assembly illustrated in FIG. 4 of the &#39;863 patent and serves to support the wash plate  75  for wobbling action without rotation relative to the wash drum or basket  83 . The invention contemplates the incorporation of the subject wobble joint  50  (also wobble joint  10 ) into such washing machine devices for supporting a wobbling wash plate  75 .