Patent Publication Number: US-2006005351-A1

Title: Omni-directional rolling support device

Description:
FIELD OF THE INVENTION  
      The present invention relates to a rolling support device and especially to a vertically oriented omni-directional rolling support device capable of highly accurate placement.  
     DESCRIPTION OF RELATED ART  
      The typical rolling support for furniture has traditionally been an offset caster. The presence of offset casters can make it difficult to accurately place an article of furniture since the caster can change orientation during movement causing the center of balance to shift. When a heavy item is placed on such a caster, it is difficult to change directions, especially in tight spaces, and often it is not possible to accurately place the furniture precisely in a desired location.  
      An individual moving such a piece of furniture supported by traditional casters will often encounter the problem where placement control is not accurate. The individual attempts to move the furniture a small distance in one direction only to find that the caster has changed position, and the furniture has shifted undesirably. Thus, the industry still requires an accurately placed, omni-directional rolling support for furniture or other articles without undue movement caused by caster reorientation.  
     BRIEF SUMMARY OF THE INVENTION  
      The present invention, as defined in the claims, overcomes these disadvantages by describing an omni-directional rolling support that is aligned along a vertical axis, so that the furniture item may be easily moved over the horizontal surface, and accurately placed, without incurring a shift due to the reorientation of an offset caster. Further, once the furniture item is positioned, a hollow support unit can be used to contact the surface around the rolling support to lock the furniture item in place.  
      According to a preferred embodiment, a cup is attached to a first end of a shaft. The cup receives a ball that is in sliding contact with the cup inner surface. The ball is in non-sliding contact with a planar surface so a supported object, such as a furniture leg, attached to the second end of the shaft. Thus, the supported object is supported against the planar surface to roll on the ball across the planar surface in any direction. The shaft can be threaded for mating with a nut or other threaded member. The position of the furniture leg relative to the cup member may be adjusted by positioning the nut on the threaded shaft.  
      A hollow support unit has an open end and a closed end, the close end can be attached to the shaft and the open end is surrounding the cup. The hollow support unit can extend and retract along a central axis so that when the hollow support unit is extended, it contacts the planar surface and inhibits rolling movement along the planar surface. The hollow support unit is preferably cylindrical in shape. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The exact nature of this invention, as well as the objects and advantages thereof, will become readily apparent upon consideration of the following specification in conjunction with the accompanying drawings in which like reference numerals designate like parts throughout the figures thereof and wherein:  
       FIG. 1  shows a side-view of the omni-directional rolling support unit according to an embodiment of the present invention.  
       FIG. 2  shows a side-view of the omni-directional rolling support unit as it is positioned in a furniture leg according to an embodiment of the present invention.  
       FIG. 3  shows a side-view of the omni-directional rolling support device as it is mounted on a horizontal member with the supported member in a position closer to the cup member according to an embodiment of the present invention.  
       FIG. 4  shows a side-view of the omni-directional rolling support device as it is mounted on a horizontal member with the supported member in a position farther away from the cup member according to an embodiment of the present invention.  
       FIG. 5  shows a side-view of the support member in a retracted position according to an embodiment of the present invention.  
       FIG. 6  shows a side-view of the support member in a second position touching the horizontal surface and inhibiting movement according to an embodiment of the present invention.  
       FIG. 7  shows a side-view of the support member in a third position touching the horizontal surface and inhibiting movement according to an embodiment of the present invention.  
       FIG. 8  shows a bottom-up end-view of the support member according to an embodiment of the present invention.  
       FIG. 9  shows an exploded view showing the cylindrical extension components of the hollow support unit according to an embodiment of the present invention.  
       FIG. 10  shows a top plan view of the hollow support unit showing the through hole for mounting the hollow support unit to the shaft according to an embodiment of the present invention.  
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Reference will now be made in detail to the preferred embodiments of the invention, examples of which are illustrated in the accompanying drawings. While the invention will be described in conjunction with the preferred embodiments, it will be understood that they are not intended to limit the invention to these embodiments. On the contrary, the intention is intended to cover alternatives, modifications and equivalents, which may be included within the spirit and scope of the invention as defined by the appended claims.  
      Furthermore, in the following detailed description of the present invention, numerous specific details are set forth in order to provide a thorough understanding of the present invention. However, it will be obvious to one of ordinary skill in the art that the present invention may be practiced without these specific details. In other instances, well known methods, procedures, components, and circuits have not been described in detail as not to unnecessarily obscure aspects of the present invention.  
      In reference to  FIG. 1 , a vertically oriented rolling support device  100  includes a cup  102  having an open end and a closed end. The cup  102  closed end is attached to one end of a shaft  104 . The other end of the shaft  104  extends away from the cup  102  on an axis aligned with a central axis  110  of the cup  102 . The shaft  104  can be considered an elongated member having a first end and a second end. Alternatively, the shaft  104  may be oriented at an oblique angle to the central axis of the cup so long as the central axis of the cup  102  is normal to the surface upon which the ball rests. In yet another alternative, the rolling support device  100  may be oriented horizontally to provide rolling support to a supported object such as a tray for carrying conveyed items against a vertical surface where the tray may by conveyed along a horizontal direction and then change to a vertical direction such as by an escalator along an assembly line.  
      The cup  102  receives a ball  106 , and the ball  106  is retained in the cup  102 . The ends of the cup  102  extend around the received ball  106  beyond the horizontal midline  112  of the ball so that the ball  106  is retained in the cup  102  after insertion. The cup  102  may be composed of metal or hard plastic while the ball  106  may be composed of plastic, TEFLON (R), or metal. The ball  106  is positioned in the cup  102  between the cup  102  and a planar surface such as a floor. The ball  106  is in sliding contact with the cup  102  inner surface  114  while the ball is in non-sliding contact with the planar surface.  
      The coefficient of static friction between the ball  106  and the planar surface is higher than the coefficient of static friction between the ball  106  and the cup  102  inner surface  114 . Therefore, even from a rest position, the ball  106  is in sliding contact with the cup  102  inner surface  114 , and in non-sliding contact with the planar surface to provide omni-directional rolling support for a supported object attached to the shaft  104  across the planar surface. The cup  102  is rotationally fixed relative to the shaft  104  so that when changing the direction of movement across the planar surface, the shaft  104  and cup  102  do not rotate. This allows accurate placement of an article of furniture, for example, and eliminates undue movement caused by off-set caster reorientation.  
      In one embodiment, a plurality of small-diameter spheres  116  are positioned between the ball  106  and the cup  102  inner surface  114 , and occupy the corners of a shoulder-like circular cavity  118  positioned radially in proximity to the closed end of the cup  102 , as shown in  FIG. 1 . The ball  106  rolls against the spheres  116  in the cavity  118 . The spheres  116  can roll against the inner surface  114  or remain stationary while the ball  106  rolls against the surface of the spheres  116 . The contact between the spherical surface of the ball  106  and the spherical surface of each sphere  116  allows for contact between the ball  106  and sphere  116  at a point, thereby reducing the friction between the ball  106  and the cup member  102  inner surface  114 . The number of small-diameter spheres  116  is at least three and as many as will fit loosely within the circular cavity  118 .  
      In one embodiment, the shaft  104  is treaded for mating with a complimentarily threaded member such as a nut  108  or other threaded member for engaging with the threaded shaft  104 , for example. If a nut  108  is mounted on the shaft  104 , the position of the nut on the shaft  104  determines the position of a supported object relative to the cup  102 , and essentially determines the height of the supported object relative to a horizontal surface when the omni-directional rolling support device is oriented vertically over the horizontal surface.  
      In reference to  FIG. 2 , the rolling support device  100  supports a portion of an article of furniture such as a furniture leg  202  where a portion of the shaft  104  is inserted into a cavity  204  within the furniture leg  202 . The shaft  104  may be surrounded by a spacing material  208  such as a plastic cylinder to flexibly engage with the shaft  104  within the cavity  204 . The cavity  204  may include a pocket of empty space  206  above the location of the shaft  104  so that when the nut  108  is rotated about the shaft  104  in a first direction, the nut advances towards the cup  102 , and the shaft  104  moves in a direction  212  farther into the cavity  204 .  
      Alternatively, when the nut  108  is rotated about the shaft  104  in a second direction, the nut  108  retreats away from the cup  102  and the shaft  104  moves in a direction  214  out of the cavity  104 . Thus, a nut  108  mounted on the threaded shaft  104  may be used in adjusting the height of the supported portion of a furniture leg  202 , for example. The nut  108  has a first side and a second side, the first side of the nut  108  is oriented towards the cup  102  (proximal) while the second side of the nut  108  is oriented away from the cup  102  (distal) and toward the furniture leg  202 .  
      A washer  210  may optionally be located between the nut  108  second side and the furniture leg  202 . The nut  108  can be adjusted to both adjust the height of the furniture as well as to level an article of furniture having more than one leg. Alternatively, the shaft  104  may be smooth, not threaded, and can maintain an adjustable height for the furniture leg  202  based the addition of a properly sized spacer, or a plurality of spacers such as the washer  210  inserted on the shaft and between the cup  102  and the furniture leg  202 .  
      In reference to  FIG. 3 , a planar portion  302  of a supported object may be securely held between a first nut  108  and a second nut  308  on the threaded shaft  104 . The planar portion  302  may be an extension of an article of furniture or may be planar portion within an article of furniture such as the bottom surface or shelf of an enclosure or cabinet. Alternatively, a first washer  210  may be placed against the second side of the first nut  108  as described previously. The upper surface of the first washer  210  is then placed adjacent to a lower surface of the planar portion  302 .  
      An optional second washer  310  is placed over the threaded shaft  104  and adjacent to the top surface of the planar portion  302  and the second nut  308  is tightened on the threaded shaft  104 . The first nut  108  and the second nut  308  are counter rotated against each other so the first nut  108  and the second nut  308  advance towards each other in order to securely hold the planar portion  302  of the supported object between them. The planar portion  302  can also be within a furniture leg  202  so that the omni-directional rolling support device  100  is held securely within the furniture leg  202 . It is understood that the furniture leg  202  must also include an opening for inserting the second nut  308  as well as an optional washer  310  and to allow tightening of the second nut  308 .  
      In reference to  FIG. 4 , the planar portion  302  is securely held at a distance away from the cup  102  compared to the view of  FIG. 3 . The position of the planar portion  302  may be adjusted to change the height of the planar portion  302  above a horizontal planar surface and to level the article of furniture as discussed.  
      In reference to  FIGS. 5-6 , a hollow support unit  502  surrounds the ball  106 , cup  102  and is attached to the shaft  104 . The hollow support unit  502  can expand and retract (advance or retreat) along a central axis in order to contact the planar surface  504 . When the hollow support unit  502  is retracted, a gap  506  exists between the planar surface  504  and the hollow support unit  502 . When the hollow support unit  502  is expanded to contact the planar surface  504 , the gap  506  is eliminated, and the hollow support unit  502  inhibits rolling of the omni-directional rolling support device  100  while providing a wider base of support for the supported object  202 .  
      A frictional member  508  may be attached on the underside of the hollow support unit  502  on a contact ring  510  in order to provide added friction between the planar surface  504  and the contact ring  510  hollow support unit  502 . The frictional member  508  may include a butyl rubber material, for example. The hollow support unit  502  in the presently preferred embodiment includes an outer cylinder  512 , a threaded contact ring  510 , and a threaded top cap  516 .  
      The outer cylinder  512  has a threaded inner portion (not shown) that mates with the threaded portions on the contact ring  510  and the threaded top cap  516  that the hollow support unit  502  can expand or contract along the central axis when the outer cylinder  512 , contact ring  510 , and the top cap  516  are rotated relative to each other. Either or both of the contact ring  510  and the top cap  516  may be extended relative to the outer cylinder  512 .  FIG. 5  shows both the contact ring  510  and the top cap  516  in a retracted position.  FIG. 6  shows only the top cap  516  extended.  FIG. 7  shows both the contact ring  510  and the top cap  516  extended in an embodiment that does not include the frictional member  508 . The threaded portion  702  of the contact ring  510  is partially shown.  
      The hollow support unit  502  preferably includes an alloy DURALUMIN, but may be composed of aluminum alloy or another suitable, high tensile-strength material. Duralumin is a particular alloy of aluminum (over 90%) with copper (about 4%), magnesium (0.5%-1%), and manganese (less than 1%). Before a final heat treatment the duralumin alloy is ductile and malleable, but after the heat treatment a reaction between the aluminum and magnesium produces an increased hardness and tensile strength. Because it is light weight and durable, duralumin is widely used in the aircraft industry.  
       FIG. 8  is an end-view of the omni-directional rolling support device  100  in the direction AA as shown in  FIG. 6 . The contact ring  510  has an inner edge  802 . In another embodiment, the hollow support unit  502  is non-cylindrical and includes an outer shell  512  and an inner shell  514  which advance or retreat along a central axis by pushing and pulling the overlapping shells through a series of detents comprising facing projections to positively position the inner and outer shells relative to each other at various positions.  
      In one alternative embodiment, the cross-sectional view as in  FIG. 8  of the non-cylindrical hollow support unit  502  is triangular in shape. In another alternative embodiment, the cross-sectional view as in  FIG. 8  of the non-cylindrical hollow support unit  502  is square in shape. Finally, in another alternative embodiment, the cross-sectional view as in  FIG. 8  of the non-cylindrical hollow support unit  502  is hexagonal in shape.  
       FIG. 9  shows an exploded view showing the cylindrical extension components ( 510 ,  516 ) separated from the outer cylinder  512  of the hollow support unit  502 .  FIG. 10  shows a top view of the hollow support unit showing the through hole for mounting the top cap  516  of the hollow support unit  502  to the shaft  104 . The through hole  1002  may be threaded to mate with a threaded shaft  104 .  
      Those skilled in the art will appreciate that various adaptations and modifications of the just-described preferred embodiments can be configured without departing from the scope and spirit of the invention. Therefore, it is to be understood that, within the scope of the amended claims, the invention may be practiced other than as specifically described herein.