Abstract:
A pivot joint comprises a receiver supported relative to a first member. The receiver is provided for receiving a second member. The receiver is partially cylindrical. A retainer is adapted to be supported relative to the first member to trap the second member in the receiver. The retainer has an arcuate shaped portion that is adapted to engage the second member. Moreover, the retainer has a resilient portion that is adapted to conform to a portion of the second member.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates in general to couplings and more particularly, to a pivot joint. Most particularly, the invention relates to a pivot joint for supporting a pivotal member relative to a stationary member. 
     Conventional pivot joints include a bearing supported on the end of a pivotal shaft. The bearing is supported in a hole in a stationary member. This type of pivotal joint is not suitable for use with a pivotal member in the form of a closed loop. 
     A conventional bearing is not really suitable for a closed loop pivotal member because the bearing must be applied to the pivotal member prior to forming the closed loop. The closed loop would more commonly be formed prior to applying a finish to the pivotal member. If a conventional bearing is applied prior to finishing or painting the pivotal member, the bearing itself would be painted, thus interfering with paint covering the pivotal member. 
     Some bearings may be applied to a pivotal member after the pivotal member is formed and painted. For example, a pillow block bearing is a bearing that may be separated in halves to receive a pivotal member and joined back together. Such a bearing assembly may be suitably applied to a pivotal member after the pivotal member is formed. However, such bearings are commonly bolted to a stationary member. 
     A flexible, compliant pivot joint is needed that permits expedient assembly of pivotal and stationary members and which accommodates manufacturing intolerance to provide a tight fit, free of play. 
     SUMMARY OF THE INVENTION 
     The present invention is directed towards a pivot joint that meets the foregoing needs. The pivot joint comprises a receiver supported relative to a first member. The receiver is provided for receiving a second member. The receiver is partially cylindrical. A retainer is adapted to be supported relative to the first member to trap the second member in the receiver. The retainer has an arcuate shaped portion that is adapted to engage the second member. Moreover, the retainer has a resilient portion that is adapted to conform to a portion of the second member. 
     Various objects and advantages of this invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, when read in light of the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a pivot joint according to the invention supporting a pivotal member relative to a stationary member. 
     FIG. 2 is an enlarged cross-sectional view of the pivot joint taken along the line  2 — 2  in FIG.  1 . 
     FIG. 3 is an exploded perspective view of a pair of pivot joints supporting a pair of pivotal members relative to a stationary member. 
     FIG. 4 is a perspective view of laterally spaced pivot joints according to the invention supporting a pair of pivotal members relative to a stationary member. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Referring now to the drawings, there is illustrated in FIG. 1 a first member  10  which is in the form of an articulated bed sleep surface section or a wheelchair seat frame. The first member  10  is coupled to a second member  12  so that the first member  10  may be displaced relative to the second member  12 . The second member  12  is in the form of a substantially stationary member, such as the main frame of an articulated bed or the base frame of a wheelchair. 
     The present invention is a pivot joint  14  for movably coupling the first and second members  10 ,  12  together. In accordance with the preferred embodiment of the invention, the pivot joint  14  is comprised of a receiver  16  and a retainer or keeper  18 . The receiver  16  may be in the form of a cradle or a cup which is adapted to be fixed relative to one of the members  10 ,  12 . As shown in the drawings, the receiver  16  is fixed relative to the first member  10  but it is conceivable that it may be fixed relative to the second member  12 . 
     The receiver  16  is preferably cylindrical in shape and adapted to receive a tube, such as a tubular portion or segment of an articulated bed sleep surface section or a wheelchair seat frame. The retainer  18  is adapted to be attached relative to the receiver  16  so as to trap the second member  12  in the receiver  16 . 
     In the preferred embodiment of the invention, the retainer  18  includes a first portion  20  and a second portion  22  joined in a spaced relation to one another by an intermediate portion  24 , as shown in FIG.  2 . The first portion  20  is defined at least in part by a hook end  26 . The hook end  26  may include a first bent portion  28  at its terminal end. The first bent portion  28  defines an inverted U-shaped member. The inverted U-shaped member forms a blunt tip for the hook end  26 . 
     The first bent portion  28  is joined in a spaced relation to a second bent portion  32  by a downwardly extending portion  30 . The second bent portion  32  defines a region that is adapted to engage a laterally extending edge  34  of a substantially horizontal member  36 , the substantially horizontal member  36  being substantially fixed relative to the receiver  16 . A substantially horizontally extending portion  38  of the hook end  26  is adapted to extend below the substantially horizontal member  36  from the second bent portion  32  to a third bent portion  40  of the hook end  26 . 
     The third bent portion  40  extends upwardly through a first opening  42  in the second member  12  and joins the intermediate portion  24  of the retainer  18 . The intermediate portion  24  is arcuate in shape and is adapted to flex about the first member  10  supported by the receiver  16  to hold the first member  10  firmly in the receiver  16 . 
     An opposing end of the intermediate portion  24  terminates in the second portion  22  of the retainer  18 . The second portion  22  is defined at least in part by a latch end  44 . In the preferred embodiment of the invention, the latch end  44  is in the form of an interference member  46  having a first engaging portion  48  extending from the intermediate portion  24 . The first engaging portion  48  terminates in a first bent portion  50 , which in turn joins a slightly bowed intermediate portion  52 . 
     A substantially S-shaped portion  54  is held in a spaced relation to the first bent portion  50  by the slightly bowed intermediate portion  52 . The S-shaped portion  54  is defined by second and third bent portions  56 ,  58  of the second portion  22 . The second bent portion  56  defines an outer cam surface  57  and is adapted to flex at least slightly, as is the first engaging portion  48  and the slightly bowed intermediate portion  52 . The third bent portion  58  defines a second engaging portion  60 . The interference member  46  is adapted to be received in a second opening  62  in the second member  12 . 
     The second opening  62  is preferably in the form of a laterally extending slot defined in part by opposing laterally extending edges. The first and second engaging portions  48 ,  60  are adapted to engage the opposing laterally extending edges. Upon inserting the interference member  46  in the second opening  62 , the first bent portion  50  enters the second opening  62 . The slightly bowed intermediate portion  52  engages and travels downwardly along a first lateral edge of the second opening  62 . The first engaging portion  48  travels downwardly along a second lateral edge. When the outer cam surface  57  engages the second lateral edge, the slightly bowed intermediate portion  52  flexes to enable the outer cam surface  57  to pass between the opposing laterally extending edges with relative ease. When the outer cam surface  57  overcomes the second lateral edge, the slightly bowed intermediate portion  52  flexes back in an opposing direction and the second lateral edge snaps into the third bent portion  58  of the S-shaped portion  54 . The first engaging portion  48 , the slightly bowed intermediate portion  52 , and the first bent portion  50  all flex at least slightly to resist displacement of the interference member  46  from the second opening  62 . 
     The latch end  44  of the retainer  18  further includes a substantially straight portion  64  extending from the third bent portion  58  of the second portion  22 . The substantially straight portion  64  is provided to assist in handling and controlling the retainer  18  and displacing the interference member  46  in the second opening  62  in the second member  12 . In the preferred embodiment of the invention, the retainer  18  is adapted to be pivotally displaced relative to the second member  12  about the hook end  26  to engage the interference member  46  in the second opening  62 . A sufficient downward force applied against the substantially straight portion  64  urges the interference member  46  into and through the second opening  62 . A sufficient upward force applied against the substantially straight portion  64  can displace the interference member  46  upwardly out of the second opening  62 . 
     A fourth bent portion  66  may be provided at a terminal end of the substantially straight portion  64 . The fourth bent portion  66  is preferably in the form of an inverted U-shaped member, which provides a blunt tip for the latch end  44 . 
     In the preferred embodiment of the invention, the receiver  16  includes a substantially semi-cylindrical sleeve  67  supported by the second member  12 . The substantially semi-cylindrical sleeve  67  is preferably adapted to receive a bushing, such as the split bushing  68  shown. The split bushing  68  is adapted to be spread open to receive the second member  12 . The use of the split bushing  68  will reduce the risk of the second member  12  wearing. 
     In the preferred embodiment of the invention, the split bushing  68  is defined by a substantially cylindrical sleeve  70  having a circumferential slit about a portion of its circumference. Radially extending flanges  72  are provided at opposing ends of the substantially cylindrical sleeve  70 . The substantially semi-cylindrical sleeve  67  is adapted to receive the substantially cylindrical sleeve  70  with the radially extending flanges  72  being disposed at opposing lateral ends of the substantially semi-cylindrical sleeve  67 . The radially extending flanges  72  are provided to resist axial displacement of the split bushing  68  relative to the receiver  16 . It may be necessary to provide circumferentially spaced notches in the radially extending flanges  72  to permit the split bushing  68  to be spread open. 
     To resist rotational displacement of the split bushing  68  relative to the receiver  16 , the split bushing  68  and the receiver  16  may be keyed relative to one another. For example, as shown in FIG. 3, the split bushing  68  may be provided with one or more keys, such as the tabs or protrusions  74  shown. The receiver  16  may be provided with one or more slots  76  that are adapted to receive respective protrusions  74 . With the protrusions  74  engaging the slots  76  and the retainer  18  fixed relative to the receiver  16 , the split bushing  68  is not inclined to slip or rotate relative to the receiver  16 . 
     In the preferred embodiment, the substantially semi-cylindrical sleeve  67  is preferably fixed relative to the receiver  16  at an angle of inclination so as to produce an elevated cylindrical wall portion  78  and a depressed cylindrical wall portion  80 , as shown in FIG.  2 . The first member  10  is adapted to rotate relative to the split bushing  68  and the substantially semi-cylindrical sleeve  67 . This rotation may be effected by an actuator (not shown) coupled to the first member  10 . The elevated cylindrical wall portion  78  is provided to reduce the risk of the first member  10  being dislodged from the substantially semi-cylindrical sleeve  67  by the force of the actuator in the direction of arrow F. 
     The preferred embodiment of the invention further includes a stop  82  which is fixed relative to the first member  10 , as shown in FIG. 3, to prevent the first member  10  from moving laterally or axially relative to the receiver  16 . As shown in FIG. 4, a single first member  10  may be supported by two laterally spaced pivot joints  14 . A pair of laterally spaced stops  82  cooperates to resist lateral or axial movement in both directions along the lateral axis of the first member  10 . 
     It should be understood that the receiver  16  need not be integral with the second member  12 . As shown in FIG. 4, the receiver  16  may be an integral part of a bracket, such as the elongate bracket  84  shown, and the first and second openings  42 ,  62  (shown in FIGS. 2 and 3) may be defined by the elongate bracket  84 . In this way, the first and second openings  42 ,  62  are provided in a fixed location relative to the elongate bracket  84 . The elongate bracket  84  may in turn be attached to the second member  12 , thus fixing the receiver  16  and the first and second openings  42 ,  62  in a substantially fixed location relative to the second member  12 . The elongate bracket  84  shown is adapted to accommodate a plurality of receivers  16 . Other brackets may be suitable for carrying out the invention, such as a bracket for supporting a single receiver  16 . 
     It should further be understood that the pivot joint is flexible and compliant. It permits expedient assembly of pivotal and stationary members. The flexible character accommodates manufacturing intolerance and provides a tight fit, free of play. 
     In accordance with the provisions of the patent statutes, the principle and mode of operation of this invention have been explained and illustrated in its preferred embodiment. However, it must be understood that this invention may be practiced otherwise than as specifically explained and illustrated without departing from its spirit or scope.