Patent Publication Number: US-2007102125-A1

Title: Sliding wheel unit for a blind

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      This invention relates to a sliding wheel unit for a blind, particularly to one having a friction member improved better than a conventional one.  
      2. Description of the Prior Art  
      A conventional sliding wheel unit for a blind shown in  FIGS. 1 and 2  is installed on an upper rod of a blind at a proper location, including a base member  11  flexibly fitting firmly in the upper rod. The base member is provided with a hollow space  111  and a rack  112 , an entrance hole  113  and an exit hole  114  respectively formed in a front wall and a rear wall for a pull rope to extend in and out. Further, a stationary wheel  12  is fixed upright in the hollow space  111 , and a movable gear  13  is positioned beside the stationary wheel  12  to engage with the rack  112  in the hollow space  11 . Then the pull rope extending in the base member  11  is sandwiched between the stationary wheel  12  and the rotatable gear  13  for fixing a blind body. Further, a U-shaped engage ring  14  is fitted in the exit hole  114  for the pull rope to be moved frictionally so that the pull rope may be prevented from snapping or worn down due to friction between the pull rope and the engage ring  14 .  
      However, the U-shaped engage ring  14  may be liable to disfigure and fall off in case the U-shaped engage ring  14  receives sliding force of the pull rope when pulled, Moreover, the U-shaped engage ring  14  is not in good in its appearance, or not easy to control in its bending precision to result in low percentage of quality test and high cost.  
     SUMMARY OF THE INVENTION  
      The feature of the sliding wheel unit for a blind in the invention is a friction member to fit in an exit hole of a base member. The friction member is provided with a circumferential wall defining a center hole for a pull rope of a blind to extend out. The circumferential wall of the friction member is provided with a position edge at an outer side and a bottom wall at the inner side, and the position edge contacts the outer side of the wall of the center hole of the base member and the bottom wall contacts the inner side of the wall of the center hole after the friction member is fitted in the exit hole of the base member, keeping it secured without falling off the center hole. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS  
      This invention will be better understood by referring to the accompanying drawings, wherein:  
       FIG. 1  is a perspective view of a conventional sliding wheel unit for a blind;  
       FIG. 2  is an exploded perspective view of the conventional sliding wheel unit for a blind;  
       FIG. 3  is a perspective view of a sliding wheel unit for a blind in the present invention;  
       FIG. 4  is an exploded perspective view of the sliding wheel for a blind in the present invention;  
       FIG. 5  is an upper cross-sectional view of a friction member fitted in place in the present invention; and,  FIG. 6  is a perspective view of the sliding wheel unit installed on a blind in the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
      A preferred embodiment of a sliding wheel unit for a blind in the present invention, as shown in  FIGS. 3, 4  and  5 , has almost the same structure of the conventional sliding wheel unit for a blind, fitted flexibly in an upper rod of a blind at a proper location, including a base member  21  and a friction member  24 .  
      The base member  21  consists of a bottom base  21  a and a cover  21   b  covered on the bottom base  21   a , with a hollow space  211  defined by the bottom base  21   a  and the cover  21   b . Further, a rack  212  is provided on the bottom base  21   a , and an entrance hole  213  is formed in the front wall of the bottom base  21  a and an exit hole  214  is formed in the rear wall of the bottom base  21   a , so a pull rope  40  may extend in through the entrance hole  211  and out of the exit hole  214 . Further, a stationary wheel  22  is installed upright in the hollow space  211 , and a rotatable gear  23  is also installed therein, engaging with the rack  22 , so the pull rope  40  may be sandwiched properly between the stationary wheel  22  and the rotatable gear  23  for connecting firmly with a blind body  50  of the blind.  
      The stationary wheel  22  has teeth around its outer surface so that the pull rope  40  may be tightly pressed by the teeth of the stationary wheel  22  and the rotatable gear  23  after extending in and out of the base member  21  and between the both  22  and  23 , but the stationary wheel  22  can also be a round column without teeth.  
      Next, the friction member  24  made integral of a metal or plastic is inserted in the exit hole  214  of the base member  21 , consisting of a circumferential wall  241  defining a center hole  242 , a position edge  243  formed projecting outward from the circumferential wall  241  and having a size a little larger than that of the exit hole  214  of the base member  21 . Further, a bottom wall  244  is formed to extend vertically outward from the inner side of the circumferential wall  241  and sized larger than that of the exit hole  214 . Then the position edge  243  extends just out of the exit hole  214  and contacts the outer side of the wall of the exit hole  214 , and the bottom wall  244  contacts the inner side of the wall of the exit hole  214 , keeping the friction member  24  in place securely.  
      The center hole  242  of the friction member  24  has an profile similar to that of the exit hole  214  of the base member  21  , almost shaped nearly rectangular with four corners curved to enable the pull rope  40  slide in and out smoothly and at the same time the frictional resistance of the wall of the center hole  242  can be low against the pull rope  40 . Further, the bottom wall  244  of the friction member  24  is also shaped rectangular.  
      In addition, as shown in  FIGS. 4 and 5 , the friction member  24  of the slide wheel unit  20  can be inserted in the exit hole  214  of the base member  21 , letting the position edge  243  of the circumferential wall  21  expose out of the exit hole  214  of the base member  21  before the cover  21   b  is covered on the bottom base  21   a . Then the position edge  243  contacts the outer side of the wall of the exit hole  214  and the bottom wall  244  contacts the inner side of the wall of the exit hole  214 , keeping the friction member  24  tightly secured in the exit hole  214 .  
      In addition, after the slide wheel unit  20  is installed in the upper rod  30  of the blind, with the pull rope  40  is properly extended in the slide wheel unit  20 , the friction member  24  may not become loose, or fall off, kept securely with the base member  21   
      Further, the frictional resistance of the pull rope  40  against the center hole  242  of the friction member  24  is substantially low, and at the same time, the friction member  24  is made of a material highly resistant against wear and tear, enabling the friction member  24  have a long service life.  
      Moreover, the friction member  24  has only a small portion of the circumferential wall  241  and the position edge  243  exposed out of the exit hole  214 , with its profile coordinating with that of the exit hole  214 , presenting comparatively beautiful appearance. Besides, the friction member  24  can be produced swiftly with high effectiveness because of pressing process with metal or plastic as its material.  
      While the preferred embodiment of the invention has been described above, it will be recognized and understood that various modifications may be made therein and the appended claims are intended to cover all such modifications that may fall within the spirit and scope of the invention.