FIELD OF THE APPLICATION 
       [0001]    The present application relates to sliding door systems for glass doors, and more particularly to a roller unit to support the glass door and allow the sliding motion of the door. 
       BACKGROUND OF THE ART 
       [0002]    Nowadays, glass and similar see-through or translucent materials are used as structural components. In that glass allows light to pass through, doors, walls and structures made from glass represents an esthetic and elegant solution. However, in these instances, the glass components must have minimum thicknesses, as they serve a structural function. 
         [0003]    Accordingly, hinges and sliding door mechanisms must be capable of handling the weight of movable components (e.g., doors). On the other hand, due to the highly esthetic value of glass doors and structures, and the fact that they are often transparent, sliding door mechanisms must be visually appealing. 
       SUMMARY OF THE APPLICATION 
       [0004]    It is therefore an aim of the present disclosure to provide a novel roller unit for use with glass sliding door systems. 
         [0005]    It is a further aim of the present disclosure to provide a sliding door system for glass doors that addresses issues associated with the prior art. 
         [0006]    Therefore, in accordance with the present application, there is provided a roller unit for a sliding door comprising: a connector assembly adapted to be secured to a structure or to a door, the connector assembly comprising a spindle; and a wheel having a rolling-element bearing operationally mounted to the spindle of the connector assembly, and an annular wheel body mounted to the rolling-element bearing for rotation about the spindle, the annular wheel body having a pair of flanges separated by a groove on a circumferential surface of the annular wheel body, the circumferential surface defining a shape corresponding to the shape of an edge portion of the door or structure engaged in the annular wheel body, the connector assembly being connected to one of the door and the structure while the wheel receives an edge portion of the other of the door and the structure, whereby the roller unit holds the door and structure face to face while allowing sliding movement of the door with respect to the structure by rotation of the wheel about the spindle. 
         [0007]    Further in accordance with the present application, there is provided a sliding door system comprising: at least one door; a transom adapted to be secured to a structure above a door opening in the structure, the transom comprising top and bottom edge surfaces each having a pair of longitudinal slanted edge surfaces separated by a longitudinal flat edge surface; at least two roller units secured to the door with at least one said roller unit operationally contacting the top edge surface of the transom, and at least one said roller unit operationally contacting the bottom edge surface of the transom, each said roller unit comprising: a connector assembly secured to the door, the connector assembly comprising a spindle, and a wheel having a bearing operationally mounted to the spindle of the connector assembly, and an annular wheel body mounted to the bearing for rotation about the spindle, the annular wheel body having a pair of flared-surface flanges separated by a groove on a circumferential surface of the annular wheel body to correspond to the shape of edge surfaces of the transom engaged in the annular wheel body, with the width of the longitudinal slanted edge surface of the transom adjacent the structure being at least equal to the width of the roller unit from the corresponding flared-surface flange to an end of the roller unit; whereby the roller units hold the door and structure face to face while allowing sliding movement of the door with respect to the structure by rotation of the wheels about the spindle to open/close the opening in the structure. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]      FIG. 1  is a front view of a sliding door system in accordance with an embodiment of the present disclosure; 
           [0009]      FIG. 2  is an exploded view of a roller unit of the sliding door system of  FIG. 1 , with a spacer; 
           [0010]      FIG. 3  is a sectional view of the roller unit of  FIG. 2 , without a spacer; 
           [0011]      FIG. 4  is a side elevation view of a glass sliding door supported by the roller units of  FIG. 2 , with a transom-supported door; and 
           [0012]      FIG. 5  is a perspective view of a glass sliding door supported by the roller units of the sliding door system of  FIG. 1 , with a slot-supported door. 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0013]    Referring to the drawings and more particularly to  FIG. 1 , a sliding door system in accordance with the present disclosure is generally shown having a pair of sliding doors  10  made of glass panels, or any other suitable panel material, or any combination of see-through or translucent materials and structural materials (e.g., wood, metal). The sliding doors  10  translate to open/close an opening in a structure  11 , in the directions shown by A. The structure  11  is typically made of glass panels as well, but may also consist of any other suitable materials or combination of materials. 
         [0014]    The doors  10  are top-hung by roller units  12  to a transom  14 . The transom  14  may be part of the structure  11 , and typically made of glass panels as well, but may also consist of other materials. The transom  14  is secured to the structure  11  by connectors  16 , above a door opening defined by the structure  11 . Although the transom  14  is illustrated as being supported by three of the connectors  16 , more or fewer connectors  16  may be used. 
         [0015]    In  FIG. 1 , the doors  10  are each shown supported by a set of four roller units  12 . However, any appropriate number of roller units  12  may be used to support a sliding door. Moreover, the roller units  12  are not restricted to being used with a top-hung sliding door as in  FIG. 1 , as will be described hereinafter. For instance, the roller units  12  may support a bottom edge of sliding panels, amongst other possibilities. 
         [0016]    Referring concurrently to  FIGS. 2 and 3 , one of the roller units  12  is shown in greater detail. The roller unit  12  has a connector assembly rotatably supporting a wheel. The roller unit  12  has an end cap  20 . The end cap  20  is visible when the roller unit  12  is assembled to a door, whereby the end cap  20  may have any appropriate ornamental features: paint, finish, ornaments. Moreover, the end cap  20  may have other shapes than that of a disk. 
         [0017]    Referring to  FIG. 3 , a shoulder  21  may be defined between a circumferential surface of the end cap  20  and one of its two circular surfaces. The shoulder  21  receives an O-ring, as will be described hereinafter. 
         [0018]    A neck  22  projects from one of the circular surfaces of the end cap  20 , and is on the same side as the shoulder  21 . The neck  22  has a tapped bore  23 , preferably not extending through the cap  20 . In the illustrated embodiment, the neck  22  and the tapped bore  23  are concentric with the end cap  20 . 
         [0019]    Referring to  FIGS. 2 and 3 , another end cap  30  is provided on the opposed end of the roller unit  12 . The end cap  30  is visible when the roller unit  12  is assembled to a door, whereby the end cap  20  may have any appropriate ornamental features. The end cap  30  has a neck  31 , and a spindle  32  projecting concentrically form the neck  31 . The neck  31  and spindle  32  are preferably concentric with the end cap  30 . The spindle  32  has a tapped bore  33 . 
         [0020]    The rolling components of the roller unit  12  are positioned between the end caps  20  and  30 . The end caps  20  and  30  define the visible face portions of the roller units  12 . 
         [0021]    Referring to  FIGS. 2 and 3 , the roller unit  12  has a middle disk  40 . The middle disk  40  has a pair of necks  41  on opposite circular surfaces. A shoulder  42  may be defined between a circumferential surface of the middle disk  40  and one of the two circular surfaces. The shoulder  42  receives an O-ring, as will be described hereinafter. 
         [0022]    A tapped throughbore  43  passes through the necks  41 . Alternatively, each neck  41  may have an own tapped bore. The tapped throughbore  43  is concentric with the necks  41 . 
         [0023]    In order to secure the roller unit  12  to a bore in a structural panel or in a door, the end cap  20  and middle disk  40  are positioned on opposite sides of the bore, in such a way that the necks  22  and  41 , respectively, enter into the bore and may contact one another. O-rings  50  are placed in the shoulders  21  and  42  beforehand, whereby the circular surfaces of the disks  20  and  40  do not come in direct contact with the structural panel. Moreover, the O-rings  50  are preferably made of a soft resilient material, to generally dampen transmission of vibrations between the panel and the roller unit  12 . The O-rings  50  also prevent water infiltration between the disks  20  and  40  and the structural panel. The O-rings or like rings of resilient material may be received in grooves on the circular surfaces alternatively to the shoulders  21  and  42 . 
         [0024]    A threaded rod  51  interconnects the disks  20  and  40 . In the embodiment of  FIG. 3 , the middle cap  40  has a throughbore  43 , whereby the threaded rod  51  also interconnects the end cap  30  to the middle disk  40 . Other constructions are also considered. For instance, the middle disk  40  may be optionally in the connector assembly. Moreover, the connector assembly may consist of any other means that is securable to a door or structure, with a spindle to rotatably support a wheel. 
         [0025]    Referring to  FIGS. 2 and 3 , a wheel  60  of the roller unit  12  is between the end cap  30  and the middle disk  40 . The wheel  60  has a bearing  61 , which may be any suitable type of bearing (e.g., roller bearing, ball bearing), and preferably of rolling-element bearing as opposed to sleeve bearings. Alternatives to rolling-element bearings may be used as well, such as annular rings of low-friction materials (e.g., PTFE) and the like. The bearing  61  is mounted on the spindle  32  of the end cap  30 , although the spindle  32  could be integral with the middle disk  40  as well. 
         [0026]    A first wheel ring  62  has an annular body and is positioned adjacent to the end cap  30  when the roller unit  12  is assembled. The wheel ring  62  has a cylindrical surface portion  63  and a flared surface portion  64 . The flared surface portion  64  is positioned adjacent to the end cap  30  when the roller unit  12  is assembled. An inner shoulder  65  projects radially inwardly from the flared surface portion  64 , in the opening of the wheel ring  62 . The inner shoulder  65  is provided to define a seat in the wheel ring  62  for the bearing  61 . Tapped bores  66  are defined in an axial surface of the wheel ring  62 , and are used to connect a second wheel ring  67  to the first wheel ring  62 . 
         [0027]    Referring to  FIGS. 2 and 3 , the second wheel ring  67  has an annular body and is positioned adjacent to the middle disk  40  when the roller unit  12  is assembled. The wheel ring  67  has a flared surface portion  68 . Countersink holes  69  are defined axially through the wheel ring  67 , and are spaced apart so as to be in register with the tapped bores  66 . Accordingly, with appropriate fasteners (e.g., with a countersunk head), the first wheel ring  62  and the second wheel ring  67  are secured to one another. An inner diameter of the wheel ring  67  is similar to that of the inner shoulder  65 , and smaller than an outer diameter of the bearing  61 , whereby the bearing  61  is held captive in the first wheel ring  62 . 
         [0028]    As shown in the embodiment of  FIG. 2 , a spacer  70  may be provided to increase the width of the wheel  60 . The spacer  70  has a cylindrical ring body having an outer diameter similar to that of the cylindrical surface portion  63  of the first wheel ring  62 . The width of the wheel  60  is selected as a function of the thickness of the panels. Axial throughbores  71  are defined in the spacer  70 , to allow the connection of the first wheel ring  62  and the second wheel ring  67  with fasteners, as described above. 
         [0029]    The wheel  60  therefore has the shape of a sheave, with the flared surface portions  64  and  68  acting as flanges, and the cylindrical surface portion  63 , and optionally the spacer  70  forming the groove between the flanges. Accordingly, when a panel having the appropriate shape is in contact with the wheel  60 , it is held captive by the sheave shape. 
         [0030]    Although a modular construction of the wheel  60  is described, it is pointed out that the wheel  60  may be an integral piece (e.g., cast, machined, or the like). However, the modular construction allows the wheel  60  to be adapted to various thicknesses of panels (e.g., 6 mm to 25 mm), by simply selecting appropriate spacer width. Accordingly, the modular construction addresses inventory issues. It is pointed out that through the description, reference is made to tapped bores and throughbores. This includes self-tapping bores. 
         [0031]    Now that the examples of construction of roller units have been described, a use of the roller units  12  in a door system is set forth. 
         [0032]    Referring to  FIG. 4 , the door  10  is shown top-hung by roller units  12  on the transom  14 . In the side view of  FIG. 4 , only two of the roller units  12  are visible, although more of the roller units  12  may be used (e.g., as shown in  FIG. 1 ). There is provided roller units  12  for contact with an upper edge of the transom  14 , and roller units for contact with a lower edge of the transom  14 . 
         [0033]    For esthetic and practical reasons, it is preferred that the door  10  be as close as possible to the structural panel  11 . In the transom-supported configuration of  FIG. 4 , it is the thickness of the transom  14  that defines the gap between the door  10  and the structural panel  11 . In order to minimize the width taken by the transom  14  between the door  10  and the structural panel  11 , the top and bottom edge surfaces of the transom  14  have a given shape. More specifically, the top and bottom edge surfaces of the transom each have beveled edge surfaces, namely a sequence of a longitudinal slanted edge surface  14 A (i.e., a beveled edge), a longitudinal flat edge surface  14 B, and another longitudinal slanted edge surface  14 C (i.e., another beveled edge). 
         [0034]    Referring concurrently to  FIGS. 3 and 4 , when the roller units  12  contact the transom  14 , the cylindrical surface portion  63  of the roller units  12  is in contact with the flat edge surface  14 B, and optionally with the spacer  70  if a spacer  70  is present in the roller units  12 . The roller unit  12  is selected as a function of the thickness of the transom  14 , and more particularly as a function of the width of the cylindrical surface portion  63 . Therefore, the flared surface portions  64  and  68  of the wheel  60  are against the slanted edge surfaces  14 A and  14 C when the roller units  12  are top-hung to the transom  14 . It is however observed that the slanted edge surface  14 A projects beyond the flared surface portion  64 . The gap between the slanted edge surface  14 A and the structural panel  11  accommodates a portion of the end cap  30 . 
         [0035]    Therefore, in the embodiment of  FIGS. 3 and 4 , the horizontal thickness of the portion of the transom  14  that features the slanted edge surface  14 A is at least equal to the combined width of the flared surface portion  64  and the end cap  30 . This ensures a minimum gap between the door  10  and the structural panel  11 . 
         [0036]    Similarly, the horizontal thickness of the portion of the transom  14  that features the slanted edge surface  14 C is at least equal to the combined width of the flared surface portion  68  and the end disk  20 . An additional space may be provided for a head of the connectors  14 C, if necessary, as shown in  FIG. 4 . This construction allow the minimization of the gap between the door  10  and structural panel  11 . 
         [0037]    Referring to  FIG. 5 , an alternative embodiment is shown in which the door  10  is top-hung by the roller units  12  to a slot  11 A in the structural panel  11 . The slot  11 A preferably has slanted edge surfaces, as was described for the top and bottom edge surfaces of the transom  14  ( FIGS. 3 and 4 ). Therefore, the gap between the door  10  and the structural panel  11  is even further reduced with the configuration of  FIG. 5 . 
         [0038]    In the embodiments of  FIGS. 4 and 5 , the roller units  12  roll on the edge surfaces of the transom  14  ( FIG. 4 ) or the slot  11 A ( FIG. 5 ). The door  10  moves in a translational fashion, which is referred to as a sliding movement. Therefore, even if roller units  12  are used causing a rotational movement transmission, the door  10  is referred to as a sliding door. It is considered to install a magnetic layer on the rolling edge surfaces of the transom  14  ( FIG. 4 ) or the slot  11 A ( FIG. 5 ), to facilitate the translational movement of the door  10 . Moreover, despite the fact that top-hung solutions are illustrated, it is considered to use the roller units  12  in other door-supporting configurations.
A roller unit comprises a connector assembly secured to a structure or to a door. The connector assembly comprises a spindle. The roller assembly has a wheel having a rolling-element bearing mounted to the spindle, and an annular wheel body mounted to the rolling-element bearing for rotation about the spindle. The annular wheel body has a pair of flanges separated by a groove on a circumferential surface of the annular wheel body. The circumferential surface defines a shape corresponding to the shape of an edge portion of the door or structure engaged in the annular wheel body. The connector assembly is connected to one of the door and the structure, while the wheel receives an edge portion of the other of the door and the structure, whereby the roller unit holds the door and structure face to face while allowing sliding movement of the door with respect to the structure by rotation of the wheel about the spindle. A sliding door system is also described.