Abstract:
The present specification discloses a carriage body ( 10 ) and a bearing ( 24 ) as a sub assembly for use in a roller wheel assembly ( 32 ), the bearing ( 24 ) centrally supporting a roller wheel supporting shaft ( 27 ) for rotation, in use, about a rotation axis defined by the rotation shaft ( 27 ), the bearing ( 24 ) having an outer peripheral mounting surface ( 50 ), the carriage body ( 10 ) being in one piece defining a bearing support cavity ( 17 ) providing a support surface ( 23 ) engaging at least a portion of the outer peripheral mounting surface ( 50 ) of the bearing ( 24 ), the one piece carriage body ( 10 ) further having a bearing access opening ( 28 ) whereby the bearing ( 24 ) is operationally positioned in the bearing support cavity ( 17 ) by movement through the access opening ( 28 ) in a direction transverse to the rotation axis defined by the support shaft ( 27 ).

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to improvements in roller wheel assemblies comprised of at least one pair of wheels supported at opposed ends of a shaft that is supported by a bearing carried by a carriage member. 
       BACKGROUND TO THE INVENTION 
       [0002]    The roller wheels of a roller wheel assembly are typically, in use, arranged to roll along a metal track, having a specific path for each roller wheel of the pair of roller wheels. Sometimes, multiple pairs of roller wheels may be provided in particular assemblies. Such assemblies are often used as an elevated rolling support for doors, windows and the like including but not limited to cavity door rolling supports. Other applications may include a variety of conveyors, particularly overhead conveyors. There are a number of known methods for mounting the bearing in the body of the carriage member including making the carriage member body in two or more parts that are connected by fasteners around the bearing, directly moulding a plastics material body about the bearing (or bearings), and press fitting the bearing in an axial direction into a purpose formed cavity for the bearing. Such arrangements are usually characterized by the outer peripheral surface of the bearing being fully supported by the body of the carriage member. Such known arrangements, while working satisfactory, have a number of disadvantages including the difficulty of the assembly process and the costs of the material required for the body of the carriage member. All these have an adverse affect on the costs of roller wheel assembly over all. The objective of the present invention is to provide an improved structure for a carriage member body for mounting at least one bearing thereto for use in a roller wheel assembly of the above discussed type. 
       SUMMARY OF THE INVENTION 
       [0003]    According to the present invention there is provided a carriage body and bearing sub assembly for use in a roller wheel assembly, said bearing having a central opening defining a rotation axis of a roller wheel supporting shaft, said bearing having an outer peripheral mounting surface, said carriage body being one piece and being characterized by a bearing support cavity having an access region opening in a first face of said carriage body, said bearing support cavity defining a support surface means, in use, engaging with a portion of the outer peripheral mounting surface of said bearing, said bearing being positioned in said bearing support cavity by movement through said access region in a direction transverse to said rotation axis. Conveniently the aforesaid first face faces in a load carrying direction of said carriage body and bearing sub assembly. Preferably said carriage body includes load carrying means for carrying a load whereby, in use, the load applies a force to said carriage body in a direction to urge said portion of the outer peripheral mounting surface of said bearing against said support surface means of said bearing support cavity. 
         [0004]    The above defined arrangement permits easy assembly of the bearing (or bearings) with the carriage body without the difficulties and costs associated with previously known manufacturing techniques. Once the roller wheel shaft and the roller wheels are connected with the shaft, the bearing (or bearings) are operationally retained in position. When the roller wheel assembly is positioned in use on a rolling track, load on the sub assembly keeps the bearing operationally in position within the single piece carriage body. If it is desired to keep the bearing in place in its operational position in the bearing support cavity, retainer means may be provided to keep the bearing operationally positioned. 
         [0005]    Preferably said outer peripheral mounting surface of said bearing is circular and said support surface means includes at least one bearing engagement location, the, or each said bearing engagement location together, defining a semi-circular contact zone for a portion of the outer peripheral mounting surface of said bearing. Conveniently the semi-circular contact zone is formed by a continuous semi-circular surface. The semi-circular contact zone in the bearing support cavity may occupy 180° or less. 
         [0006]    In a preferred arrangement, the aforesaid semi-circular contact zone has a generally uniform width in the axial direction corresponding to a width of said outer peripheral mounting surface of said bearing. The outer peripheral mounting surface of the bearing may be annular and generally parallel to the rotation axis. 
         [0007]    Conveniently, adjacent to the semi-circular contact zone, at least one region may be provided having a smaller radius of curvature than a radius of curvature of said semi-circular contact zone, being adapted to retain said bearing in said bearing support cavity. 
         [0008]    In an alternative arrangement, retainer means may be provided to retain said bearing in said bearing support cavity. Conveniently, the retainer means may include at least one integrally formed formation on said carriage body adjacent said bearing support cavity. The retainer means may enable the bearing to be forced past said retainer means into said bearing support cavity but inhibit movement of the bearing in a reverse direction. 
         [0009]    Preferably the carriage body may include a first wall means and a second wall means generally on opposed sides of said bearing support cavity extending from said first face, each of said first and said second wall means having aperture means enabling a said roller wheel supporting shaft to pass therethrough and through said bearing support cavity, at least one of said first and said second wall means being continuous in said first face. Conveniently both said first and said second walls means are continuous in said first face. 
         [0010]    In many preferred arrangements, the carriage body may have a plurality of said bearing support cavities, each having a separate said access region to said first face and each carrying a said bearing. Conveniently, the multiple said bearings are arranged in substantially the same plane. 
         [0011]    In a further preferred aspect of this invention, a roller wheel assembly is provided including a carriage body and bearing sub assembly according to any one of the options defined in the foregoing, the roller wheel assembly further including a roller wheel supporting shaft carried by the or each said bearing, the or each said roller wheel supporting shaft carrying a roller wheel on each lateral end of said shaft. In a preferred aspect the roller wheel assembly may also include a hanger rod threaded into a retainer nut held within a retainer nut cavity in said carriage body, said hanger rod passing through an aperture in said first face, said retainer nut cavity being substantially open in a face opposite said first face except for diametrally opposed retainer tabs engaging said retainer nut. 
         [0012]    Further preferred features of the present invention will become apparent from the following description of preferred embodiments given in relation to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]      FIG. 1  is a perspective view of an integrally moulded plastic material carriage body according to one preferred embodiment; 
           [0014]      FIG. 2  is a top plan view of  FIG. 1 ; 
           [0015]      FIG. 3  is a section view along line X-X of  FIG. 2 ; 
           [0016]      FIG. 4  is an end view from either end of the carriage body shown in  FIG. 1 ; 
           [0017]      FIG. 5  is a detailed view of the area marked A in  FIG. 3 ; 
           [0018]      FIG. 6  is a perspective view of a carriage body similar to  FIG. 1  where the carriage body is made by a metal die casting procedure; 
           [0019]      FIG. 7  is a top plan view of  FIG. 6 ; 
           [0020]      FIG. 8  is a section view along line X-X of  FIG. 7 ; 
           [0021]      FIG. 9  is an end view of either end of the carriage body shown in  FIG. 6 ; 
           [0022]      FIG. 10  shows in perspective view, one possible roller wheel assembly including the carriage body of  FIGS. 1 to 5  together with bearings located in the bearing support cavity. 
           [0023]      FIG. 11  is a top plan view of  FIG. 10 ; 
           [0024]      FIG. 12  is a section view along line X-X of  FIG. 11 ; 
           [0025]      FIG. 13  is a forward end view of the assembly shown in  FIG. 10 ; and 
           [0026]      FIG. 14  is an exploded perspective view of the roller wheel assembly shown in  FIG. 10 . 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0027]    Referring first to  FIGS. 1 to 5 , a one piece carriage body  10  is illustrated that may be moulded from any suitable plastics material that has the strength and hard wearing capabilities for the intended application. The carriage body  10  has a lower first face  11 , an upper second face  12 , a first side wall  13 , a second side wall  14  and opposed end walls  15 ,  16 . As is apparent from the drawings, the aforesaid faces and walls are not necessarily continuous or flat. As will be apparent from the following, the carriage body  10  illustrated is intended to enable a roller wheel assembly having four roller wheels mounted on two spaced parallel shafts, however, it is possible to ultimately provide roller wheel assemblies having one pair of roller wheels mounted to a single shaft up to any number of pairs of roller wheels, depending on application and required load carrying capacity. 
         [0028]    As shown in  FIG. 3 , a pair of spaced bearing support cavities  17  are provided each being located between end walls  15 ,  16  and respective intermediary walls  18 ,  19  extending between the side walls  13 ,  14 . Each of the side walls  13 ,  14  have an opening  20  leading into the bearing support cavity  17 . Each of the side walls  13 ,  14  further include a ledge region  21  extending from the first face  11  upwardly into the bearing support cavity  17  and around the opening  20  returning again to the first face  11 . The distance between the ledge regions  21  on each of the side walls  13 ,  14  generally equals the axial thickness of the outer face of the bearing to be installed. The inner surfaces facing inwardly of the bearing support cavities  17  of the end walls  15 ,  16 , the intermediary walls  18 ,  19  and the wall  22  providing a substantial part of the second face  12 , provide support for the peripheral surface of the outer ring of the bearing, either as the bearing enters the bearing support cavity  17  or as the bearing is operationally seated on the bearing support cavity  17  with said peripheral surface of the outer ring of the bearing seated against the inner surface  23  of the wall  22 . 
         [0029]    Conventionally, the peripheral surface  50  of the outer ring  25  of the bearing  24  will be circular and the inner surface  23  forming a support surface of the bearing support cavity  17  is semicircular having substantially equal radius of curvatures as this provides maximum bearing support for the outer ring  25  of the bearing  24 . This structure is not, however essential for the performance of the present invention. The width of the surface  50  in the axial direction is substantially equal to the width of the surface  23  in an axial direction. The width of the ledge regions  21  that is, the distance from the surface  23  to the edge of the opening  20  is sufficient to support the outer ring  25  of the bearing but not so much as to obstruct the inner ring  26  of the bearing  24 .  FIG. 12  schematically illustrates the bearings  24  in the bearing support cavities  17  with the outer ring  25  engaged against the surface  23 , and the inner ring  26  supporting a roller wheel support shaft  27  having a rotation axis out of the plane of the paper, i.e. transverse to the openings  20  in the side walls  13 ,  14 . As illustrated, the support surface  23  is semicircular occupying about 180°, however the support surface  23  might occupy a smaller angular distance or be broken up into separate support surfaces or locations. The surface  23  might have a uniform width in the axial direction and preferably will be flat in each radial plane and in each radial plane, will be parallel to the rotation axis. The surface  23  represented in the drawings is continuous but it is equally possible to have a series of circumferentially spaced bearing engagement locations that together form a semi-circular contact zone. The arrangement is, however such as to provide an open access region  28  in the first face  11  of the carriage body  10  that allows the bearing  24  to enter the bearing support cavity in a direction transverse to the rotation axis of the bearing or the shaft supported by bearing  24 . The open access region  28  conveniently has a length equal to or greater than the diameter of the outer ring of the bearing  24 . The width of the access region  28 , i.e. the distance between the ledge regions  21  conveniently approximates the axial width of the bearing outer ring  25 . 
         [0030]    If it is desired that the bearing  24  be mechanically retained in the bearing support cavity  17 , a region  30  of decreased radius b relative to the radius a of the surface  23  may be provided at the entrance to the region of the surface  23 . This may provide a reduced distance zone less than the diameter of the bearing outer ring  24  at a position slightly lower than the maximum diameter of the bearing support cavity  17  to provide a retainer means that the bearing  24  can be readily pushed past into the cavity  17  but will be retained therein once it has been pushed into the cavity  17 . While the region  30  provides one means of achieving this result, it will be apparent to those skilled in the art that many other forms of retainer means could be provided. For example, limited regions of increased thickness might be moulded on one or both ledges  21  acting as similar retainer means. 
         [0031]    As can be seen in  FIG. 12 , and other figures, the side walls  13 ,  14  provide a region  31  below the shaft  27  that fully retains the shaft  27  and the bearing  24  in their operational position once the roller wheel assembly  32  is assembled as shown in  FIG. 10  with roller wheels  33  secured to ends of the shafts  27 . In use the roller wheel assembly  32  has a load applied to it in a downward direction ( FIG. 12 ), i.e. in the same direction as the access region  28  is open, such that in use, this loading also prevents the bearing or bearings  24  from being dislodged from their operational position ( FIG. 12 ). 
         [0032]      FIG. 12  further illustrates a hanger rod  34  supporting an assembly structure  35  adapted to be connected in use, to a desired load, for example a sliding door, sliding window or the like. The upper end of the hanger rod  34  passes through an opening  36  in a wall  37  which connects between the intermediary walls  18 ,  19 . The hanger rod  34  passes into a nut retaining cavity  38  containing a nut  39  and is screw threaded into the nut  39 . A pair of small tabs  40 ,  41  defines the upper end of the nut retaining cavity  38  and is engaged with the nut  39 . Conveniently, the nut  39  is a lock nut. The nut  39  might be placed in the cavity  38  through an opening  44  in the side wall  13 . 
         [0033]      FIG. 14  illustrates the assembly in exploded fashion. The shafts  27  preferably have circumferential grooves  42  adjacent their lateral ends that are engaged with ribs (not shown) in the bores  43  of the roller wheels  33  when assembled. The shafts  27 , when assembled fit through the inner bore  51  of the bearings  24  and are rotationally supported by the inner bearing ring  26 . Conveniently the bearings  24  can be press fitted into the support cavities  17  by being pressed in the direction of arrows  52  through the access openings  28 . Once the bearings  24  are in an operational position in the cavities  17 , the shafts  27  can be pressed through the bearing inner bores  51  with the shaft lateral ends extending through the openings  20  in the side walls  12 ,  13 . In this condition the bearings  24  cannot fall out of the support cavities  17  with or without the bearing retainer means discussed above. Preferably, the roller wheels  33  can be press fitted into the ends of the shafts  27 . While this structure is preferred, other known forms of connecting the roller wheels  33  to the shafts  27  can be employed. 
         [0034]      FIGS. 1 to 5  and  11  to  14  show one possible arrangement of the carriage body  10  manufactured by moulding a suitable plastics material.  FIGS. 6 to 10  illustrate another possible construction where the carriage body  10  is produced from a suitable metal. Any known construction process can be used including die casting, other casting process and forging. In this arrangement the hanger rod  34  might simply be screw threaded into a threaded bore  45  in a central zone  46 . Other like features have been given the same reference numbers from the earlier described embodiments. Other variations may be possible within the scope of the annexed claims. For example, the carriage body  10  might be made in one piece but assembled with other parts in a complete assembly.