Abstract:
A caster for providing rolling support including a spring-loaded mount. The caster may be substantially concealed in the bottom edge of a hinged, swinging door, and generally located proximate to the free vertical edge of the door. An elongated spring plate is provided as a mount for a roller, causing the roller to accommodate variations in the floor surface, maintain contact with the floor, and support the door. The spring plate has a first portion adapted to be mounted to the bottom edge of a door, and a second portion depending from the first portion. An axle is mounted to the second portion, inside a hub that is mounted to the roller. The axle may be substantially parallel to the first portion of the spring plate. Single roller and double roller caster assemblies are provided.

Description:
BACKGROUND  
       [0001]     The present invention relates to the field of casters for providing rolling support of objects, and more particularly concerns casters that may support swinging doors.  
         [0002]     Casters are often used to provide rolling support for loads in a variety of applications. In general, casters include a kingpin mounted to an object, a bracket mounted to the kingpin, an axle mounted to the bracket, and a wheel or roller mounted to the axle. The bracket, axle, and wheel may swivel around the kingpin.  
         [0003]     Casters are often used with doors, gates, or other similar hinged, swinging objects. Doors may sag at their free vertical edge, as hinges do not always maintain the door in the originally installed alignment. Sagging becomes an increasingly significant issue for heavy and wide doors, resulting in a larger moment about the hinges. Casters are mounted to the door such that the roller is positioned between the bottom edge of the door and the floor, typically adjacent the free vertical edge of the door. The caster allows swinging movement of the door between closed and open positions while providing uplifting force to place and maintain the door in position.  
         [0004]     Some casters used for doors, gates, or the like, may also include a coil or leaf spring to allow vertical displacement of the roller relative to the door to maintain contact with the floor, in case of variation in elevation of the floor relative to the door, as the door swings. The coil-type spring may be disposed around a telescoping kingpin or other similar arrangement. Alternatively, the spring may be leaf-type, being wrapped around an axle on each side of a roller. With such arrangements the orientation of the axle is perpendicular to the longer dimension of the leaf spring, and the direction of the movement of the roller is aligned with the longer dimension of the leaf spring.  
         [0005]     In some cases, for aesthetic reasons, it may be desirable to conceal casters within the doors. Concealed casters may be desirable in, for example, heavy, wide, commercial doors in high-end offices, but may also be desirable elsewhere. Concealment requires that the caster fit within the thickness of a door. Most often the caster arrangement on doors is disposed in plain view.  
         [0006]     Accordingly, there exists a need for a new caster for a door. Ideally, the new caster may be substantially concealed in the door, and may maintain contact with the floor over the extent of the door&#39;s movement.  
       SUMMARY  
       [0007]     In accordance with an embodiment of the present invention, a caster for a door includes an elongated resilient spring plate including a first portion and a second portion depending from the first portion. The first portion of the plate is adapted to be mounted to the door. An axle is mounted to the second portion of the plate such that the axle is substantially parallel to the first portion of the plate. A roller is operatively connected, in other words mounted directly or indirectly, to the axle, such that at least a part of the roller rotates. A hub may be disposed between the axle and the roller. The roller may be a self-aligning bearing.  
         [0008]     In accordance with another embodiment of the present invention, a caster for a door includes an elongated resilient spring plate, a hub, an axle, and a roller. The elongated resilient spring plate includes a first portion and a second portion depending from the first portion. The first portion of the plate is adapted to be mounted to the door. The axle is mounted to the second portion of the plate such that the axle is substantially parallel to the first portion of the plate, and the second portion of the plate has a slot for receiving the axle. The slot is sized for allowing the distance between the axle and the first portion of the plate to be adjusted. The axle comprises a threaded rod. The hub is mounted to the axle. The roller is mounted to the hub, and has a substantially tight interference fit with the hub.  
         [0009]     In accordance with another embodiment of the present invention, a door includes a door and a caster. The door includes a first major surface and a second major surface, and a hinged vertical edge, a free vertical edge, a top edge, and a bottom edge. The bottom edge is between and interconnects the first major surface and the second major surface and has a recessed surface defined between the first and second major surface of the door adjacent to the free vertical edge. The caster includes an elongated resilient spring plate, an axle, and a roller. The plate includes a first portion and a second portion depending from the first portion, wherein the first portion of the plate is mounted to the door in the recess such that the second portion is free from attachment to the door. The axle is mounted to the second portion of the plate such that the axle is substantially parallel to the first portion of the plate. The roller is operatively connected to the axle, and at least a portion of the roller rotates.  
         [0010]     In accordance with another embodiment of the present invention, a caster for a door includes an elongated resilient spring plate including a first portion and a second portion depending from the first portion, the first portion of the plate adapted to be mounted to the door. A bracket includes a first portion and a second portion angularly extending from the first portion of the bracket, and the first portion of the bracket is mounted to the second portion of the plate. A hub has opposed ends and is mounted to the second portion of the bracket such that the hub is substantially parallel to the first portion of the plate, and the ends of the hub define openings. An axle is disposed in the open ends of the hub. A roller is operatively connected to each axle, wherein at least a part of each roller rotates.  
         [0011]     In accordance with another embodiment of the present invention, a caster for a door includes an elongated resilient spring plate including a first portion and a second portion depending from the first portion, the first portion of the plate adapted to be mounted to the door. A bracket includes a first portion and a second portion angularly extending from the first portion of the bracket, and the first portion of the bracket is mounted to the second portion of the plate. A clamp includes a rectangular portion and flanges along two opposed edges of the clamp. The clamp is adapted to be mounted to the first portion of the bracket and the second portion of the plate. The flanges of the clamp receive the edges of the first portion of the bracket and the second portion of the plate. A hub has opposed ends and is mounted to the second portion of the bracket. The hub is substantially parallel to the first portion of the plate and the ends of the hub define threaded openings. An axle includes at least one threaded rod, disposed in the threaded ends of the hub. Two rollers are provided, with one each mounted to the outside of each end of the hub and operatively connected to the axle. Each roller may include a self-aligning bearing.  
         [0012]     In accordance with another embodiment of the present invention, a door includes a door and a caster. The door includes a first major surface and a second major surface, and a hinged vertical edge, a free vertical edge, a top edge, and a bottom edge. The bottom edge is between and interconnecting the first major surface and second major surface and having a recess defined between the first and second major surfaces adjacent to the free vertical edge. The caster includes an elongated resilient spring plate including a first portion and a second portion depending from the first portion. The first portion of the plate is mounted to the door in the recess such that the second portion is free from attachment to the door. A bracket includes a first portion and a second portion angularly extending from the first portion of the bracket, with the first portion of the bracket mounted to the second portion of the plate. A hub is mounted to the second portion of the bracket such that the hub is substantially parallel to the first portion of the plate. The ends of the hub define threaded openings. The axle is mounted to the open ends of the hub such that the axle is substantially parallel to the first portion of the plate. Two rollers are provided, with one each mounted to each end of the hub.  
         [0013]     In accordance with another embodiment of the present invention, a method of making a caster for a door includes providing an elongated resilient spring plate including a first portion and a second portion depending from the first portion. The first portion of the plate is adapted to be mounted to the door. An axle is mounted to the second portion of the plate such that the axle is substantially parallel to the first portion of the plate, and a roller is operatively connected to the axle.  
         [0014]     In accordance with another embodiment of the present invention, a method of making a caster includes providing an elongated resilient spring plate including a first portion and a second portion depending from the first portion. The first portion of the plate is adapted to be mounted to the door. A bracket is provided including a first portion and a second portion angularly extending from the first portion of the bracket. The first portion of the bracket is mounted to the second portion of the plate. A hub has a central portion and two opposed ends with each end defining threaded openings. The central portion of the hub is mounted to the second portion of the bracket. A roller is mounted to each end of the hub. An axle is inserted through the roller and at least into the open ends of the hub. The axle is secured.  
         [0015]     Features and advantages of the present invention will become more apparent in light of the following detailed description of some embodiments thereof, as illustrated in the accompanying figures. As will be realized, the invention is capable of modifications in various respects, all without departing from the invention. Accordingly, the drawings and the description are to be regarded as illustrative in nature, and not as restrictive. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0016]      FIG. 1  is a perspective view of an embodiment of a caster including a single roller according to the present invention.  
         [0017]      FIG. 2  is an exploded perspective view of the caster of  FIG. 1 .  
         [0018]      FIG. 3  is a partially exposed elevation view of a door including the caster of  FIG. 1 .  
         [0019]      FIG. 4  is an exploded perspective view of a cover plate assembly for use with an embodiment of a caster according to the present invention.  
         [0020]      FIG. 5  is a perspective view of another embodiment of a caster including two rollers according to the present invention.  
         [0021]      FIG. 6  is an exploded perspective view of the caster of  FIG. 5 .  
         [0022]      FIG. 7  is a partially exposed elevation view of a door including the caster of  FIG. 5 . 
     
    
     DESCRIPTION  
       [0023]     In the Figures herein, unique features receive unique reference numerals, while features that are the same in more than one drawing receive the same reference numerals throughout. Where a feature is modified between figures or is modified only by a change in location, a letter may be added or changed after the feature reference numeral to distinguish that feature from a similar feature in a previous figure or the same feature in an alternate location. Further, certain terms of orientation may be used, such as “horizontal,” “vertical,” “upper,” “lower,” “top,” “bottom,” “left,” “right,” “inside,” “outside,” “inner,” and “outer.” These terms are generally for convenience of reference, and should be so understood unless a particular embodiment requires otherwise. Where the terms “horizontal” and “vertical” are used, they should be understood to mean “approximately horizontal” and “approximately vertical,” respectively.  
         [0024]     The scope of the invention is not intended to be limited by materials listed herein, but may be carried out using any materials that allow construction and operation. Materials and dimensions depend on the particular application. In general the materials of the components may be metal, and selectively may be plastic, as known by one of ordinary skill in the art.  
         [0025]     Referring now to the drawings, an embodiment of a spring caster  20  according to the present invention is shown in  FIGS. 1 and 2 . The caster  20  includes a cantilever-type spring plate  22  with a horizontal portion  24  having openings  26   a - 26   d  for mounting screws  28   a - 28   d  and washers  30   a - 30   d  at one end and downturned vertical portion  34  at the other end. Shims  32   a - 32   c  are provided for vertical adjustment relative to the door during installation.  
         [0026]     A roller assembly including a hub  36 , a roller  38 , and an axle  40  is provided. The hub  36  has a smaller diameter portion  42  and a larger diameter portion  44 . The roller  38  includes an inner ring  46 , an outer ring  48 , and ball bearings (not shown). The outer ring  48  rotates relative to the inner ring  46 . The smaller diameter portion  42  of the hub  36  may fit in the inner ring  46  with a substantially tight interference fit, such that there is no relative movement between the hub  36  and inner ring  46 . The inner ring  46  comprises a self-aligning ball bearing, including two raceways in which ball bearings are disposed. The outer ring  48  has one raceway. The inside of the outer ring raceway forms a spherical surface whose center coincides with the bearing center and has no defined path. The ball bearing design allows misalignment of the inner ring  46  and outer ring  48 . An example suitable self-aligning bearings is Part #IT-0139A-0703, Crown Roller with Self-Aligning Bearing by Intech Corporation of Closter, Ill. Other bearings may be selected by one of ordinary skill in the art.  
         [0027]     The axle  40  in this embodiment is a machine screw including a threaded end portion, as may be selected by one of ordinary skill in the art. The axle  40  may also be, for example, a threaded rod, with or without portions unthreaded, with or without a head, or a bolt. Where reference is made to a threaded rod, it should be understood to include screws, bolts, rods with or without heads, rods omitting threads over some portion, or the like. The axle  40  may be aligned substantially parallel with the longitudinal axis of the spring plate  22 , with the direction of movement of the roller  38  perpendicular to the spring plate longitudinal axis.  
         [0028]     The axle  40  extends through the hub  36 , roller  38 , and a vertical slot  50  in the vertical portion  34  of the spring plate  22 . A nut  52  is threaded onto the threaded end portion of the axle  40  for securing the hub  36  and roller  38  to the vertical portion of the plate  22 . A star washer  54  and lock washer  56  are provided to pre-load the assembly  20  and to prevent turning and loosening of the axle  40 . The slot  50  in the vertical portion  34  of the spring plate  22  allows vertical adjustment of the connection of the roller  38  relative to the horizontal portion of the spring plate  22 . The nut  52  may be sized and shaped to help prevent loosening by causing the nut to collide with the horizontal portion  24  of the spring plate  22  when the nut tries to turn. For example, the nut  52  may be a rectangular threaded block, as shown, or the like.  
         [0029]      FIG. 3  shows a complete door and caster assembly  60 , including a door  62  and the embodiment of a caster  20  from  FIGS. 1 and 2 . A portion of the face of the door  62  is removed to expose the caster  20  and an end plate assembly  64 . The caster assembly  20  is disposed in a recessed area  66  formed in the bottom edge of the door  62 . The horizontal portion  24  of the spring plate is secured to the door  62  with screws  28   a - 28   d.  The spring plate  22  is cantilevered from the mounting screws  28   a - 28   d  distal from the free vertical edge  70  of the door, and has a free end  72  proximate to the free vertical edge of the door. Because the spring plate  22  is flexible and resilient, the free end  72  of the spring plate  22  may move up and down to support the door  62  and for the roller  38  to contact the floor  74  as necessary. In the embodiment shown there are three steps  76 - 78  to the recessed area, with the depth of each step from the bottom edge  80  of the door  62  increasing as the distance to the edge  70  of the door  62  decreases. The stepped recessed area  66  provides space for the roller assembly. It should be understood that more or as few as no steps could be used by adjusting the number of shims  32   a - 32   c , thickness of shims, or both.  
         [0030]     An embodiment of an end plate assembly  64  is shown in  FIG. 4  and includes an end plate  90 , two screws  92   a ,  92   b  that extend through two openings  94   a ,  94   b , and two resilient electrometric strips  96   a ,  96   b . The elastomeric strips  96   a ,  96   b  provide a load on the screws  92   a ,  92   b  to keep them from loosening.  
         [0031]     The end plate assembly  64  conceals the caster assembly  20  from the free vertical edge  70  of the door  62  if necessary, which is the case if there is an opening on the free vertical edge  70 . The entire caster assembly  20  is substantially concealed between the faces of the door  62 , except for the portion of the roller  38  that extends beneath the bottom edge  80  of the door. In many applications the roller  38  will not be visible from the viewing position of someone using the door  62 , though the roller  38  need not be concealed.  
         [0032]      FIGS. 5 and 6  show another embodiment of a caster  100  according to the present invention. The caster  100  has a double roller assembly  102  that may be desirable when the load on the caster exceeds the capacity of the single roller caster  20  described above ( FIGS. 1-3 ). The spring plate arrangement of the double roller caster  100  is similar to that of the single roller caster  20 . The parts of this embodiment of the caster  100  which are identical to those of the caster  20  according to above embodiment are denoted by identical reference numbers and will not be described in detail below.  
         [0033]     An angle bracket  104  and a C-shaped clamp  106  are provided for securing the double roller assembly  102  to the spring plate  22 . The angle bracket  104  has a vertical portion  108  and a horizontal portion  110 , with an opening  112   a ,  112   b  through each portion. The vertical portion  108  of the bracket  104  and the vertical portion  34  of the spring plate  22  are received between the ends of the clamp  106 . A screw  114  extends through a lock washer  116 , a vertical slot  118  in the clamp  106 , the opening  112   a  in the vertical portion  108  of the bracket  104 , and the slotted opening  50  in the vertical portion  34  of the spring plate  22 . The vertical slots  50 ,  118  allow the double roller assembly  102  to be adjusted relative to the horizontal portion  24  of the spring plate  22 . A nut  52  is threaded onto the end of the screw  114  for securing the angle bracket  104  and clamp  106  to the vertical portion  34  of the plate.  
         [0034]     The double roller assembly  102  includes a hub  122 , two rollers  38   a ,  38   b , and axles  124   a ,  124   b . The hub  122  is double ended  124   a ,  126   b , and has a central portion  128  that includes a planar surface  130  having a threaded opening  132 . The planar surface  132  is the mounting surface for the horizontal portion  110  of the bracket  104 . A screw  134  extends through a lock washer  136  and the opening  112   b  in the horizontal portion  110  of the bracket  104 . The screw  134  and lock washer  136  mount the spring plate  22  via the bracket  104  to the hub  122 . The threaded opening  132  receives the screw  134  to secure the bracket  104 . The ends  126   a ,  126   b , the central portion  128 , or both, of the hub  122  may be threaded and may accept two screws  124   a ,  124   b  with star washers  140   a ,  140   b  and lock washers  142   a ,  142   b . As with the hub  36  of the single roller assembly, the ends  124   a ,  124   b  of the hub  126  of the double roller assembly  102  have a smaller diameter portion  144   a ,  144   b  and a larger diameter portion  146   a ,  146   b . The smaller diameter portion  144   a ,  144   b  of the ends  126   a ,  126   b  of the hub  122  may extend into the inner ring  46   a ,  46   b  of the roller  38   a ,  38   b  with a substantially tight interference fit. The larger diameter portion  146   a ,  146   b  is contiguous with the central portion  128  of the hub  122 . The rollers  38   a ,  38   b  may again be self-aligning bearings having an inner ring  46   a ,  46   b  and an outer ring  48   a ,  48   b , or alternatively other types of bearings as selected by one of ordinary skill in the art. The axles  124   a ,  124   b  pass through each end  126   a ,  126   b  of the hub  122  and each roller  38   a ,  38   b . Large washers  148   a ,  148   b  are provided between the hub  122  and rollers  38   a ,  38   b  to prevent wear of the rollers against the ends  126   a ,  126   b  of the hub  122 . An alternative design may allow one bolt to pass through the entire hub  126  and make up the axle.  
         [0035]     Like  FIG. 3 ,  FIG. 7  shows a complete door and caster assembly  150 , including a door  62  and the embodiment of a caster  100  from  FIGS. 5 and 6 . A portion of the face of the door  62  is removed to expose the caster  100  and end plate assembly  64 . The caster  100  is disposed in the recessed area  66  formed in the bottom edge of the door. As in the embodiment  60  previously described, because the spring plate  22  is flexible and resilient, the free end  72  of the spring plate  22  may deflect and apply upward force to support the door  62 . The entire caster assembly  100  is substantially concealed between the faces of the door  62 , except for a portion of the rollers  38   a ,  38   b , which need not be concealed and which extends beneath the bottom edge  80  of the door  62 .  
         [0036]     Specific embodiments of an invention are described herein. One of ordinary skill in the caster and door support arts will recognize that the invention has other applications in other environments. In fact, many embodiments and implementations are possible. For example, the caster could be applied to articles other than doors. The caster of the present invention may have varying designs of mounts of the axles and rollers to the spring plates. More than two rollers may be provided. In addition, the recitation “means for” is intended to evoke a means-plus-function reading of an element in a claim, whereas, any elements that do not specifically use the recitation “means for,” are not intended to be read as means-plus-function elements, even if they otherwise include the word “means.” The following claims are in no way intended to limit the scope of the invention to the specific embodiments described.