Patent Publication Number: US-2015075937-A1

Title: Bearing structure

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to a structure and more particularly to a bearing structure. 
     2. Description of Related Art 
     A bearing is a machine element that constrains relative motion between moving parts to only the desired motion. The design of the bearing may, for example, provide for free linear movement of the moving part or for free rotation around a fixed axis; or, it may prevent a motion by controlling the vectors of normal forces that bear on the moving parts. Many bearings also facilitate the desired motion as much as possible, such as by minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads (forces) applied to the parts. Specially, a unidirectional bearing only allows a shaft to rotate at one direction; in other words, a rotation at another direction of the shaft is prohibited. 
     However, if the shaft is unexpectedly rotated at another direction, the unidirectional bearing would be broken. 
     The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional. 
     SUMMARY OF THE INVENTION 
     The main objective of the present invention is to provide an improved bearing structure. 
     To achieve the objective, a bearing structure comprises an outer ring, an inner ring, a middle base and a plurality of roller sets, the middle base sandwiched in between the outer ring and the inner ring, the middle base assembled at a center of the outer ring, the middle base having an assembling hole opened at a center thereof, the inner ring assembled in the assembling hole, a rotation of the inner ring driving the middle base to rotate, the rotation of the middle base driving the outer ring to rotate, the middle base having a plurality of positioning openings opened on a wall of the assembling hole therethrough, each positioning opening having two grooves respectively defined at two opposite walls thereof, each roller set assembled in each corresponding positioning opening, two ends of each roller set respectively inserted into the two grooves of each corresponding positioning opening, an elastomer assembled in each positioning opening, the elastomer located between the two grooves, two ends of the elastomer respectively abutting against another wall of each positioning opening and one end of each corresponding roller set. 
     Wherein, each positioning opening has a positioning hole opened at another wall thereof; one end of the elastomer abuts against a bottom of the positioning hole of each positioning opening; each roller set has a roller member and a frame; the frame has two pivot aims defined at one end thereof; the two pivot arms are spaced from each other, so that the frame is U-shaped; each pivot arm is assembled at each corresponding groove; the roller member is assembled between the two pivot arms; the roller member is rotatable between two ends of the two pivot arms; the frame has a rod defined at another end thereof; another end of the elastomer is mounted around the rod and abuts against the frame of each corresponding roller set; a shape of the assembling hole is the same as a shape of the inner ring; the assembling hole and the inner ring are both polygonal. 
     Further benefits and advantages of the present invention will become apparent after a careful reading of the detailed description with appropriate reference to the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of the present invention; 
         FIG. 2  is a perspective view for showing each groove and each roller set defined in the present invention; 
         FIG. 3  is an exploded view of the present invention; 
         FIG. 4  is an exploded view for showing each groove and each roller set defined in the present invention; 
         FIG. 5  is a cross-sectional view for showing an inner ring being clockwise rotated; and 
         FIG. 6  is a cross-sectional view for showing the inner ring being counterclockwise rotated. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1-4 , a bearing structure in accordance with the present invention comprises an outer ring  1 , an inner ring  2 , a middle base  3  and a plurality of roller sets  4 . The inner ring  2  is hexagon-shaped. The middle base  3  is sandwiched in between the outer ring  1  and the inner ring  2 . The middle base  3  is assembled at a center of the outer ring  1 . The middle base  3  has an assembling hole  31  opened at a center thereof. A shape of the assembling hole  31  is the same as a shape of the inner ring  2 . The assembling hole  31  and the inner ring  2  are both polygonal. The inner ring  2  is assembled in the assembling hole  31 . A rotation of the inner ring  2  drives the middle base  3  to rotate. The rotation of the middle base  3  drives the outer ring  1  to rotate. The middle base  3  has a plurality of positioning openings  32  opened on a wall of the assembling hole  31  therethrough. Each two adjacent positioning openings  32  are spaced from each other. Each positioning opening  32  has two grooves  33  respectively defined at two opposite walls thereof. Each roller set  4  is assembled in each corresponding positioning opening  32 . Two ends of each roller set  4  are respectively inserted into the two grooves  33  of each corresponding positioning opening  32 . An elastomer  5  is assembled in each positioning opening  32 . The elastomer  5  is located between the two grooves  33 . Two ends of the elastomer  5  respectively abut against another wall of each positioning opening  32  and one end of each corresponding roller set  4 . A recovery force of the elastomer  5  pushes each roller set  4  away from another wall of each corresponding positioning opening  32 . 
     Furthermore, each roller set  4  has a roller member  41  and a frame  42 . The frame  42  has two pivot arms  421  defined at one end thereof. The two pivot arms  421  are spaced from each other, so that the frame  42  is U-shaped. Each pivot arm  421  is assembled at each corresponding groove  33 . The roller member  41  is assembled between the two pivot arms  421 . The roller member  41  is rotatable between two ends of the two pivot arms  421 . The frame  42  has a rod  422  defined at another end thereof. Each positioning opening  32  has a positioning hole  321  opened at another wall thereof, so that one end of the elastomer  5  corresponds to another wall of each positioning opening  32 . One end of the elastomer  5  is inserted into the positioning hole  321 , so that one end of the elastomer  5  abuts against a bottom of the positioning hole  321  of each positioning opening  32 ; another end of the elastomer  5  is mounted around the rod  422  and abuts against the frame  42  of each corresponding roller set  4  (as shown in  FIGS. 3-4 ). Each of two ends of the roller member  41  is inserted into each corresponding groove  33 , so that each roller set  4  is smoothly movable along the two grooves  33  in each positioning opening  32 ; therefore, when each roller set  4  is moved along the two grooves  33  in each positioning opening  32 , the roller member  41  and the frame  42  would not be unexpectedly derailed from the two grooves  33  (as shown in  FIGS. 2 and 4 ). 
     Under this arrangement, when the inner ring  2  is not rotated yet, the roller member  41  is clockwise and counterclockwise rotatable in each positioning opening  32 ; the roller member  41  is not clamped by the outer ring  1  and the inner ring  2  yet. Referring to  FIG. 5 , when the inner ring  2  is clockwise rotated, the roller member  41  is counterclockwise rotated by the clockwise rotation of the inner ring  2  and is moved along the two grooves  33  toward each corresponding outer corner of the inner ring  2 , until the roller member  41  is tightly clamped by an inner wall of the outer ring  1  and each corresponding outer corner of the inner ring  2 ; as a result, the outer ring  1  is rotated by the clockwise rotation of the inner ring  2 , because the roller member  41  is tightly clamped by the outer ring  1  and the inner ring  2 . Referring to  FIG. 6 , in contrast, when the inner ring  2  is counterclockwise rotated, the roller member  41  is clockwise rotated by the counterclockwise rotation of the inner ring  2  and is moved along the two grooves  33  back toward the elastomer  5 , until the roller member  41  is released from the inner wall of the outer ring  1  and each corresponding outer corner of the inner ring  2 ; simultaneously, the recovery force of the elastomer  5  pushes against the roller member  41  so as to be prevent the roller member  41  from moving over; as a result, the outer ring  1  is not rotated by the counterclockwise rotation of the inner ring  2 , because the roller member  41  is released from the outer ring  1  and the inner ring  2 . 
     Furthermore, an annular cover portion  34  is assembled at one outer side of the middle base  3 . The annular cover portion  34  corresponds to each positioning opening  32 . The annular cover portion  34  is configured to prevent outside dust from flowing into each positioning opening  32 . 
     All in all, the present invention would not be broken even if the inner ring  2  is unexpectedly rotated at a wrong direction (such as a counterclockwise direction in the embodiment of the present invention). 
     Although the invention has been explained in relation to its preferred embodiment, it is to be understood that many other possible modifications and variations can be made without departing from the spirit and scope of the invention as hereinafter claimed.