Patent Publication Number: US-2005141953-A1

Title: Positioning structure for a telescopic device

Description:
BACKGROUND OF THE INVENTION  
      1. Field of the Invention  
      The present invention relates to a telescopic device, and more particularly to a positioning structure for a telescopic device.  
      2. Description of the Prior Arts  
      A conventional telescopic device, as shown in  FIG. 1 , generally includes a pipe  10  and rod  20 . Wherein the pipe  10  is interiorly provided along the axial direction with a passage  11 , and at an end of which is defined with an annular flange  12 . A first end of the rod  20  is telescopic section  21  and a second end of which is working section  22  which is bent and connected to the telescopic section  21 . Furthermore, on the telescopic section  21  a locking groove  211  is defined perpendicular to the axial direction. In the locking groove  211  is respectively received a spring  212  and a locking member  213 . The rod  20  is telescopically received in the passage  11  of the pipe  10 , since the annular flange  12  of the pipe  10  stops the locking member  213 , which prevents the disengagement of the rod  20  from the pipe  10 . This kind of telescopic device seems to be practical in some ways, however there are still some disadvantages of it need to be improved:  
      First, the locking groove  211  has to be defined on the rod  20 , and in which the spring  212  and the locking member  213  are received sequentially in order to prevent the disengagement of the rod  20  from the pipe  10 . Since the locking groove  211 , the spring  212  and the locking member  213  are small in size, the production and the assembly of which are not easy, as a result, the production cost will accordingly be increased.  
      Second, during movement of the rod  20 , the only resistance between the rod  20  and the pipe  10  is the pushing force that the spring  212  pushing against the locking member  213 , due to the pushing force is too weak, when the telescopic device stands upright, the extended rod  20  will automatically fall down to its original position because of gravity. So a big noise will be produced after the rod  20  struck the pipe  10 .  
      The present invention has arisen to mitigate and/or obviate the afore-described disadvantages of the conventional positioning structure for a telescopic device.  
     SUMMARY OF THE INVENTION  
      The primary object of the present invention is to provide a telescopic device, a rod of which is equipped with locking rings which are able to produce drag force during extension or retraction of the rod. This structure not only helps to improve the smooth operation of the telescopic device but also reduce the striking noise. In addition, the locking ring also can prevent disengagement of the rod from a pipe of the telescopic device.  
      In accordance with one aspect of the present invention, there is provided with a positioning structure for a telescopic device that generally comprises a pipe, a rod and locking ring, wherein the pipe is interiorly provided along the axial direction with a passage for slidably receiving the rod. On the external periphery of the rod the locking ring is defined thereon for snuggly abutting against the internal surface of the pipe, which will produce drag forces during the movement of the rod and make the movement sticky, and thus the operational noise of the telescopic device can be substantially reduced. In addition, since the annular flange of the pipe stops the locking ring, the rod is prevented from disengaging from the pipe.  
      The present invention will become more obvious from the following description when taken in connection with the accompanying drawings, which shows, for purpose of illustrations only, the preferred embodiment in accordance with the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  is a partial cross sectional view of a conventional telescopic device;  
       FIG. 2  is an exploded view of a telescopic device in accordance with the present invention;  
       FIG. 3  is a cross sectional view of the present invention of showing the rod being in the state of extending;  
       FIG. 4  is another cross sectional view of the present invention of showing the rod being in the state of retracting;  
       FIG. 5  is an exploded view of a telescopic device in accordance with another embodiment of the present invention;  
       FIG. 6  is an exploded view of a telescopic device in accordance with another embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
      Referring to  FIGS. 2-4 , wherein a positioning structure for a telescopic device in accordance with the present invention is shown and generally comprised of a pipe  30 , a rod  40  and a locking ring  50 .  
      The pipe  30  is interiorly provided along the axial direction with a passage  31 , at a first end of the pipe  30  is defined an annular flange  32  and at a second end of which is provided with a grip handle  33  for user&#39;s grip.  
      The rod  40  is slidably received in the passage  31  of the pipe  30 , an end of which is a telescopic section  41 , next to the telescopic section  41  is a bent working section  42 . An end of the working section  42  can be used to fit different types of sleeve. Furthermore, on the rod  40  adjacent to the end of the telescopic section  41  is formed with a ring groove  43 .  
      The locking ring  50 , made of metal, is formed with a gap  51  and through which the locking ring  50  can be locked in the ring groove  43  of the rod  40 . Here in this embodiment takes a C-shaped retainer ring with outward restoring force as an example. The outer periphery of the locking ring  50  abuts closely against the internal surface of the pipe  30 , the locking ring  50  protrudes a little out of the ring groove  43  of the rod  40  when no pressure is applied and in compression it can be compressed into the ring groove  43 .  
      Referring to  FIGS. 3 and 4 , wherein the rod  40  is received in the pipe  30 . The locking ring  50  closely abuts against the internal surface of the pipe  30  with its outer periphery, which will produce drag force during the movement of the rod  40  and make the rod movement sticky, but the rod  40  still can move freely. It will be noted that when the telescopic device stands upright, the drag force generated by the locking ring  50  counteracts part of gravity of the rod  40  so as to slow down the speed of the free fall of the rod  40 . When the drag force is too big, the fall of the rod  40  will be stopped and the user has to push it back with his hand. In this case, the rod  40  will not strike the pipe  30  and accordingly no big noise will be caused. Moreover, in operation, when the rod  40  extends to maximum length, it will not disengage from the pipe  30  since the annular flange  32  of the pipe  30  stops the locking ring  50 .  
      Referring to  FIG. 5 , to increase the drag force between the rod  40  and the pipe  30 , the rod  40  can be additionally provided on the outer periphery with plural ring grooves  43 , and in each of the ring grooves  43  is received a locking ring  50 . In this manner, the drag force can be increased during the movement of the rod  40 , and the operational noise can be reduced to the least.  
      Referring to  FIG. 6 , wherein the locking ring  50  can be in form of wave ring, the protrusive outer periphery of the wave locking ring  50  also can abut closely against the internal surface of the pipe  30 , so as to make the extension or retraction sticky.  
      While we have shown and described various embodiments in accordance with the present invention, it should be clear to those skilled in the art that further embodiments may be made without departing from the scope of the present invention.